Locating and characterizing a crack in concrete with diffuse ultrasound: A four-point bending test.

PubMed

Larose, Eric; Obermann, Anne; Digulescu, Angela; Planès, Thomas; Chaix, Jean-Francois; Mazerolle, Frédéric; Moreau, Gautier

2015-07-01

This paper describes an original imaging technique, named Locadiff, that benefits from the diffuse effect of ultrasound waves in concrete to detect and locate mechanical changes associated with the opening of pre-existing cracks, and/or to the development of diffuse damage at the tip of the crack. After giving a brief overview of the theoretical model to describe the decorrelation of diffuse waveforms induced by a local change, the article introduces the inversion procedure that produces the three dimensional maps of density of changes. These maps are interpreted in terms of mechanical changes, fracture opening, and damage development. In addition, each fracture is characterized by its effective scattering cross section.

Electromagnetic Measurements in an Active Oilfield Environment

NASA Astrophysics Data System (ADS)

Weiss, C. J.; Aur, K. A.; Schramm, K. A.; Aldridge, D. F.; O'rourke, W. T.

2016-12-01

An important issue in oilfield development is mapping fracture distributions (either natural or man-made) controlling subsurface fluid flow. Although microseismic monitoring has been successful in constraining fracture system geometry and dynamics, accurate interpretation of microseismic data can be confounded by factors such as complex or poorly-understood velocity distributions, reactivation of previously unknown faults and fractures, and the problem of relating flow patterns to the cloud of hypocenter locations. For the particular problem of hydrocarbon production, the question of which fractures remain sufficiently "open" to allow economical fluid extraction is critical. As a supplement to microseismic analysis, we are investigating a novel electromagnetic (EM) technique for detecting and mapping hydraulic fractures in a hydrocarbon or geothermal reservoir by introducing an electrically conductive contrast agent into the fracturing fluid. In the field experiment presented here, a proppant-filled fracture zone is illuminated by a large engineered antenna consisting of an insulated current-carrying cable, grounded to `Earth' near the wellhead, and grounded at the other end to the steel-cased borehole near the target. Time-lapse measurements of horizontal electric field are subsequently made on Earth's surface to map the change in subsurface conductivity due to proppant emplacement. As predicted by 3D numerical modelling, observed differences in electric field values are very small. While these numbers are above the noise floor of electric field sensors, pervasive anthropogenic EM noise and regional-scale magnetotelluric signals make extraction of the differences from the observed time series especially difficult. We present field-acquired data on ambient EM noise in an active oilfield environment and demonstrate techniques for extracting the difference signal due to proppant emplacement. These techniques include classical spectral methods along with estimation of time-domain Green's function by regularized, linear least squares methods.

Lidar-based fracture characterization: An outcrop-scale study of the Woodford Shale, McAlister Shale Pit, Oklahoma

NASA Astrophysics Data System (ADS)

Hanzel, Jason

The use of lidar (light detection and ranging), a remote sensing tool based on principles of laser optometry, in mapping complex, multi-scale fracture networks had not been rigorously tested prior to this study despite its foreseeable utility in interpreting rock fabric with imprints of complex tectonic evolution. This thesis demonstrates lidar-based characterization of the Woodford Shale where intense fracturing could be due to both tectonism and mineralogy. The study area is the McAlister Shale Pit in south-central Oklahoma where both the upper and middle sections of the Woodford Shale are exposed and can be lidar-mapped. Lidar results are validated using hand-measured strike and dips of fracture planes, thin sections and mineral chemistry of selected samples using X-ray diffraction (XRD). Complexity of the fracture patterns as well as inaccessibility of multiple locations within the shale pit makes hand-measurement prone to errors and biases; lidar provides an opportunity for less biased and more efficient field mapping. Fracture mapping with lidar is a multi-step process. The lidar data are converted from point clouds into a mesh through triangulation. User-defined parameters such as size and orientation of the individual triangular elements are then used to group similar elements into surfaces. The strike and dip attribute of the simulated surfaces are visualized in an equal area lower hemisphere projection stereonet. Three fracture sets were identified in the upper and middle sections with common orientation but substantially different spatial density. Measured surface attributes and spatial density relations from lidar were validated using their hand-measured counterparts. Thin section analysis suggests that high fracture density in the upper Woodford measured by both the lidar and the hand-measured data could be due to high quartz. A significant finding of this study is the reciprocal relation between lidar intensity and gamma-ray (GR), which is generally used to infer outcrop mineralogy. XRD analysis of representative samples along the common profiles show that both GR and lidar intensity were influenced by the same minerals in essentially opposite ways. Results strongly suggest that the lidar cannot only remotely map the geomorphology, but also the relative mineralogical variations to the first order of approximation.

A successful development of subtle traps: Chihuido de la Sierra Negra, Neuquen Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comeron, R.; Valenzuela, M.W.

1996-08-01

Using new traps search concepts in the Chihuido de la Sierra Negra oil field, it was possible to substantially increase production from 4400 bbl/day in 1984 to 125,000 bbl/day in 1995. Oil reserves are located within an 8000 ha area situated on the Chihuido de la Sierra Negra anticlinal flank. Success was achieved by using different techniques for subtle traps detection, namely seismic amplitude mapping, individualization of different production facies and its predictive mapping. This reduced the search and development toward low structural areas which had not been considered before. The production layers are formed by two lower Cretaceous eolianmore » sandstones called the Avile Member and the Troncoso Lower Member, with thicknesses ranging from 5 to 30 meters. 2D seismic made it possible to individualize the thickest sand areas, some of which turned out to be productive. Using 3D seismic, by means of azimuth and dip maps, fractured areas were detected where fault throws range from 5 to 10 meters. In many of these fractured zones, thin igneous intrusives are emplaced forming seals. Such determinations make it possible for different oil-water contacts and static pressures to be delimited. Due to the small fault throws, the different blocks could not be detected by conventional mapping methods. The delineation of the field compartmentalization becomes important in the waterflooding stage as well as for the detection of new traps in surrounding areas. The combination of seismic and stratigraphic methods made it possible to discover and develop Argentina`s main oil field.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoak, T.E.; Klawitter, A.L.

Fractured production trends in Piceance Basin Cretaceous-age Mesaverde Group gas reservoirs are controlled by subsurface structures. Because many of the subsurface structures are controlled by basement fault trends, a new interpretation of basement structure was performed using an integrated interpretation of Landsat Thematic Mapper (TM), side-looking airborne radar (SLAR), high altitude, false color aerial photography, gas and water production data, high-resolution aeromagnetic data, subsurface geologic information, and surficial fracture maps. This new interpretation demonstrates the importance of basement structures on the nucleation and development of overlying structures and associated natural fractures in the hydrocarbon-bearing section. Grand Valley, Parachute, Rulison, Plateau,more » Shire Gulch, White River Dome, Divide Creek and Wolf Creek fields all produce gas from fractured tight gas sand and coal reservoirs within the Mesaverde Group. Tectonic fracturing involving basement structures is responsible for development of permeability allowing economic production from the reservoirs. In this context, the significance of detecting natural fractures using the intergrated fracture detection technique is critical to developing tight gas resources. Integration of data from widely-available, relatively inexpensive sources such as high-resolution aeromagnetics, remote sensing imagery analysis and regional geologic syntheses provide diagnostic data sets to incorporate into an overall methodology for targeting fractured reservoirs. The ultimate application of this methodology is the development and calibration of a potent exploration tool to predict subsurface fractured reservoirs, and target areas for exploration drilling, and infill and step-out development programs.« less

Hypogeal geological survey in the "Grotta del Re Tiberio" natural cave (Apennines, Italy): a valid tool for reconstructing the structural setting

NASA Astrophysics Data System (ADS)

Ghiselli, Alice; Merazzi, Marzio; Strini, Andrea; Margutti, Roberto; Mercuriali, Michele

2011-06-01

As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the "Grotta del Re Tiberio" cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors' surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area ( e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures ( e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping gypsum is more exposed to dissolution and recrystallization. The hypogeal geological survey, therefore, can be considered a powerful tool for integrating the surface and log data in order to enhance the reconstruction of the deformational history and to get a three-dimensional model of the bedrock in karst areas.

Study of application of ERTS-A imagery to fracture related mine safety hazards in the coal mining industry

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J. (Principal Investigator); Russell, O. R.; Amato, R. V.

1973-01-01

The author has identified the following significant results. The utility of ERTS-1/high altitude aircraft imagery to detect underground mine hazards is strongly suggested. A 1:250,000 scale mined lands map of the Vincennes Quadrangle, Indiana has been prepared. This map is a prototype for a national mined lands inventory and will be distributed to State and Federal offices.

Mapping Inherited Fractures in the Critical Zone Using Seismic Anisotropy From Circular Surveys

NASA Astrophysics Data System (ADS)

Novitsky, Christopher G.; Holbrook, W. Steven; Carr, Bradley J.; Pasquet, Sylvain; Okaya, David; Flinchum, Brady A.

2018-04-01

Weathering and hydrological processes in Earth's shallow subsurface are influenced by inherited bedrock structures, such as bedding planes, faults, joints, and fractures. However, these structures are difficult to observe in soil-mantled landscapes. Steeply dipping structures with a dominant orientation are detectable by seismic anisotropy, with fast wave speeds along the strike of structures. We measured shallow ( 2-4 m) seismic anisotropy using "circle shots," geophones deployed in a circle around a central shot point, in a weathered granite terrain in the Laramie Range of Wyoming. The inferred remnant fracture orientations agree with brittle fracture orientations measured at tens of meters depth in boreholes, demonstrating that bedrock fractures persist through the weathering process into the shallow critical zone. Seismic anisotropy positively correlates with saprolite thickness, suggesting that inherited bedrock fractures may control saprolite thickness by providing preferential pathways for corrosive meteoric waters to access the deep critical zone.

Influence of Subjectivity in Geological Mapping on the Net Penetration Rate Prediction for a Hard Rock TBM

NASA Astrophysics Data System (ADS)

Seo, Yongbeom; Macias, Francisco Javier; Jakobsen, Pål Drevland; Bruland, Amund

2018-05-01

The net penetration rate of hard rock tunnel boring machines (TBM) is influenced by rock mass degree of fracturing. This influence is taken into account in the NTNU prediction model by the rock mass fracturing factor ( k s). k s is evaluated by geological mapping, the measurement of the orientation of fractures and the spacing of fractures and fracture type. Geological mapping is a subjective procedure. Mapping results can therefore contain considerable uncertainty. The mapping data of a tunnel mapped by three researchers were compared, and the influence of the variation in geological mapping was estimated to assess the influence of subjectivity in geological mapping. This study compares predicted net penetration rates and actual net penetration rates for TBM tunneling (from field data) and suggests mapping methods that can reduce the error related to subjectivity. The main findings of this paper are as follows: (1) variation of mapping data between individuals; (2) effect of observed variation on uncertainty in predicted net penetration rates; (3) influence of mapping methods on the difference between predicted and actual net penetration rate.

Mapping fracture flow paths with a nanoscale zero-valent iron tracer test and a flowmeter test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Chiu, Yung-Chia; Teng, Mao-Hua; Liou, Sofia Ya Hsuan

2018-02-01

The detection of preferential flow paths and the characterization of their hydraulic properties are important for the development of hydrogeological conceptual models in fractured-rock aquifers. In this study, nanoscale zero-valent iron (nZVI) particles were used as tracers to characterize fracture connectivity between two boreholes in fractured rock. A magnet array was installed vertically in the observation well to attract arriving nZVI particles and identify the location of the incoming tracer. Heat-pulse flowmeter tests were conducted to delineate the permeable fractures in the two wells for the design of the tracer test. The nZVI slurry was released in the screened injection well. The arrival of the slurry in the observation well was detected by an increase in electrical conductivity, while the depth of the connected fracture was identified by the distribution of nZVI particles attracted to the magnet array. The position where the maximum weight of attracted nZVI particles was observed coincides with the depth of a permeable fracture zone delineated by the heat-pulse flowmeter. In addition, a saline tracer test produced comparable results with the nZVI tracer test. Numerical simulation was performed using MODFLOW with MT3DMS to estimate the hydraulic properties of the connected fracture zones between the two wells. The study results indicate that the nZVI particle could be a promising tracer for the characterization of flow paths in fractured rock.

Relationship of roof falls in underground coal mines to fractures mapped on ERTS-1 imagery. [Indiana and Illinois

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J.; Russell, O. R.; Amato, R. V.; Leshendok, T. V.

1974-01-01

ERTS imagery is of unique value for mapping of certain fractures that are not identifiable on aircraft imagery. Because color infrared and ERTS imagery complement each other both sources of data were used to map fractures in western Indiana and eastern Illinois. In the Kings Station Mine, Gibson County, Indiana, most roof falls reported had occurred in areas where mapped fractures were closely spaced and intersecting. Using this information as a basis for extrapolation, roof fall hazard maps were prepared for other mine sites. Various coal resources programs related to energy and environment also were conducted.

Mapping Fractures in KAERI Underground Research Tunnel using Ground Penetrating Radar

NASA Astrophysics Data System (ADS)

Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon

2016-04-01

The proportion of nuclear power in the Republic of Korea occupies about 40 percent of the entire electricity production. Processing or disposing nuclear wastes, however, remains one of biggest social issues. Although low- and intermediate-level nuclear wastes are stored temporarily inside nuclear power plants, these temporary storages can last only up to 2020. Among various proposed methods for nuclear waste disposal, a long-term storage using geologic disposal facilities appears to be most highly feasible. Geological disposal of nuclear wastes requires a nuclear waste repository situated deep within a stable geologic environment. However, the presence of small-scale fractures in bedrocks can cause serious damage to durability of such disposal facilities because fractures can become efficient pathways for underground waters and radioactive wastes. Thus, it is important to find and characterize multi-scale fractures in bedrocks hosting geologic disposal facilities. In this study, we aim to map small-scale fractures inside the KAERI Underground Research Tunnel (KURT) using ground penetrating radar (GPR). The KURT is situated in the Korea Atomic Energy Research Institute (KAERI). The survey target is a section of wall cut by a diamond grinder, which preserves diverse geologic features such as dykes. We conducted grid surveys on the wall using 500 MHz and 1000 MHz pulseEKKO PRO sensors. The observed GPR signals in both frequencies show strong reflections, which are consistent to form sloping planes. We interpret such planar features as fractures present in the wall. Such fractures were also mapped visually during the development of the KURT. We confirmed their continuity into the wall from the 3D GPR images. In addition, the spatial distribution and connectivity of these fractures are identified from 3D subsurface images. Thus, we can utilize GPR to detect multi-scale fractures in bedrocks, during and after developing underground disposal facilities. This study was supported by Korea National Research Foundation (NRF) grants NRF-2012M2A8A5007440 and NRF-2013R1A1A1076071 funded by the Ministry of Science, ICT & Future Planning, Korea.

Microstructure-Texture-Mechanical Properties in Hot Rolling of a Centrifugal Casting Ring Blank

NASA Astrophysics Data System (ADS)

Qin, Fang-cheng; Li, Yong-tang; Qi, Hui-ping; Ju, Li

2016-03-01

Deformation characteristic of centrifugal casting 25Mn steel was investigated by compression tests, and then processing maps were established. According to the deformation parameters identified from the established processing maps and hot ring rolling (HRR) process, the industrial test for the 25Mn ring blank was performed. Optical microscope (OM) and electron backscatter diffraction (EBSD) techniques were used for detecting grain boundary features and textures of deformation structures. The morphologies and mechanisms of tensile and impact fracture were revealed. The results show that softening effect plays a dominant role in higher temperatures of 1050-1150 °C and strain rates lower than 0.1 s-1. The average grain size of the rolled 25Mn ring is about 28 μm, but the grains are more coarse and inhomogeneous on the middle layer than that on rest of the areas. The texture on the outer layer is characterized by strong {110} <112> and weak {112} <111>, followed by {001} <100> and {001} <110> on the inner layer and {110} <110> on the center layer, which is mainly associated with the shear deformation. The rolled ring with precise geometrical dimensions and sound mechanical properties is fabricated by HRR. Tensile fracture is composed of clear river-shaped pattern and a little dimple near the inner layer and outer layer, and the fracture mechanism is mainly quasi-cleavage fracture, accompanied by dimple fracture. The morphologies of impact fracture consist of tear ridge and cleavage platform.

Model based rib-cage unfolding for trauma CT

NASA Astrophysics Data System (ADS)

von Berg, Jens; Klinder, Tobias; Lorenz, Cristian

2018-03-01

A CT rib-cage unfolding method is proposed that does not require to determine rib centerlines but determines the visceral cavity surface by model base segmentation. Image intensities are sampled across this surface that is flattened using a model based 3D thin-plate-spline registration. An average rib centerline model projected onto this surface serves as a reference system for registration. The flattening registration is designed so that ribs similar to the centerline model are mapped onto parallel lines preserving their relative length. Ribs deviating from this model appear deviating from straight parallel ribs in the unfolded view, accordingly. As the mapping is continuous also the details in intercostal space and those adjacent to the ribs are rendered well. The most beneficial application area is Trauma CT where a fast detection of rib fractures is a crucial task. Specifically in trauma, automatic rib centerline detection may not be guaranteed due to fractures and dislocations. The application by visual assessment on the large public LIDC data base of lung CT proved general feasibility of this early work.

Candidate-penetrative-fracture mapping of the Grand Canyon area, Arizona, from spatial correlation of deep geophysical features and surficial lineaments

USGS Publications Warehouse

Gettings, Mark E.; Bultman, Mark W.

2005-01-01

Some aquifers of the southwestern Colorado Plateaus Province are deeply buried and overlain by several impermeable shale layers, and so recharge to the aquifer probably is mainly by seepage down penetrative-fracture systems. The purpose of this 2-year study, sponsored by the U.S. National Park Service, was to map candidate deep penetrative fractures over a 120,000-km2 area, using gravity and aeromagnetic-anomaly data together with surficial-fracture data. The study area was on the Colorado Plateau south of the Grand Canyon and west of Black Mesa; mapping was carried out at a scale of 1:250,000. The resulting database constitutes a spatially registered estimate of deep-fracture locations. Candidate penetrative fractures were located by spatial correlation of horizontal- gradient and analytic-signal maximums of gravity and magnetic anomalies with major surficial lineaments obtained from geologic, topographic, side-looking-airborne-radar, and satellite imagery. The maps define a subset of candidate penetrative fractures because of limitations in the data coverage and the analytical technique. In particular, the data and analytical technique used cannot predict whether the fractures are open or closed. Correlations were carried out by using image-processing software, such that every pixel on the resulting images was coded to uniquely identify which datasets are correlated. The technique correctly identified known and many new deep fracture systems. The resulting penetrative-fracture-distribution maps constitute an objectively obtained, repeatable dataset and a benchmark from which additional studies can begin. The maps also define in detail the tectonic fabrics of the southwestern Colorado Plateaus Province. Overlaying the correlated lineaments on the normalized-density-of-vegetation-index image reveals that many of these lineaments correlate with the boundaries of vegetation zones in drainages and canyons and so may be controlling near-surface water availability in some places. Many derivative products can be produced from the database, such as fracture-density-estimate maps, and maps with the number of correlations color-coded to estimate the possible quality of correlation. The database contained in this report is designed to be used in a geographic information system and image-processing systems, and most data layers are in georeferenced tagged image format (Geotiff) or ARC grids. The report includes 163 map plates and various metadata, supporting, and statistical diagram files.

Surface Radiation Survey at the Shepley’s Hill Remediation Site, Devens, Massachusettes

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. R. Giles; C. P. Oertel; L. G. Roybal

2009-09-01

The Idaho National Laboratory (INL) provided technical support for ongoing environmental remediation activities at the Shepley’s Hill remediation site, near Devens, MA. The technical support included the completion of a radiation survey of naturally occurring radioactive materials (NORM) at Shepley’s Hill, Shepley’s Hill landfill cover, and Red Cove areas. The objective of the radiation survey was to assess the ability of the INL backpack sodium iodide spectroscopy (BaSIS) system to detect elevated levels of NORM that may be associated with radon-222 emanation from near surface and subsurface fractures in the area. It is postulated that these fracture zones provide subsurfacemore » conduits for the transport of environmental contaminants. As such, location of these fracture sets will proved EPA Region 1 with the means for completing the development of an accurate site conceptual model. The results of the radiological survey show that some of the radiological anomalies correlate with currently mapped rock outcrops; however, not all of the rock outcrops in the surveyed area have been mapped. As such, it is not conclusive that all of the radiological anomalies correspond with surface rock outcrops. EPA Region 1 intends to perform a more comprehensive correlation of the radiation data collected with the BaSIS system with additional data sets such as detailed bedrock structural mapping, 2-dimensional resistivity profiling, and high-resolution topographic mapping. The results of this effort will be used in consideration of designing a potential follow-on effort for mapping of radon.« less

Lineaments and fracture traces, Decatur County, Indiana

USGS Publications Warehouse

Greeman, Theodore K.

1983-01-01

Well placement is important in a fractured bedrock terrane, as fractures are a principal source of water to the well. Here, the most productive bedrock wells are at the mapped intersection of two or more fracture traces or lineaments and at the lowest local altitude. Use of a fracture-trace map will not guarantee a sufficient supply of ground water but will reduce the chance of drilling an inadequate well.

Facilitating the exploitation of ERTS imagery using snow enhancement techniques

NASA Technical Reports Server (NTRS)

Wobber, F. J. (Principal Investigator); Martin, K. R.; Amato, R. V.

1973-01-01

The author has identified the following significant results. Detection and analysis of fracture systems can be more effectively conducted utilizing snow cover as an enhancement tool. From analysis within the Great Barrington Test Site it appears that the use of aeromagnetic data effectively supplements lineament data acquired using ERTS imagery. Coincidence of lineaments derived from aeromagnetics with lineaments interpreted from ERTS imagery apparently indicate the presence of mineralized fracture systems and dikes. Utilizing both tools can increase the speed and efficiency of mineral exploration and geological mapping in areas where bedrock is obscured by a thick unconsolidated sediment cover.

FRACOR-software toolbox for deterministic mapping of fracture corridors in oil fields on AutoCAD platform

NASA Astrophysics Data System (ADS)

Ozkaya, Sait I.

2018-03-01

Fracture corridors are interconnected large fractures in a narrow sub vertical tabular array, which usually traverse entire reservoir vertically and extended for several hundreds of meters laterally. Fracture corridors with their huge conductivities constitute an important element of many fractured reservoirs. Unlike small diffuse fractures, actual fracture corridors must be mapped deterministically for simulation or field development purposes. Fracture corridors can be identified and quantified definitely with borehole image logs and well testing. However, there are rarely sufficient image logs or well tests, and it is necessary to utilize various fracture corridor indicators with varying degrees of reliability. Integration of data from many different sources, in turn, requires a platform with powerful editing and layering capability. Available commercial reservoir characterization software packages, with layering and editing capabilities, can be cost intensive. CAD packages are far more affordable and may easily acquire the versatility and power of commercial software packages with addition of a small software toolbox. The objective of this communication is to present FRACOR, a software toolbox which enables deterministic 2D fracture corridor mapping and modeling on AutoCAD platform. The FRACOR toolbox is written in AutoLISPand contains several independent routines to import and integrate available fracture corridor data from an oil field, and export results as text files. The resulting fracture corridor maps consists mainly of fracture corridors with different confidence levels from combination of static and dynamic data and exclusion zones where no fracture corridor can exist. The exported text file of fracture corridors from FRACOR can be imported into an upscaling programs to generate fracture grid for dual porosity simulation or used for field development and well planning.

Lineaments and fracture traces, Jennings County and Jefferson Proving Ground, Indiana

USGS Publications Warehouse

Greeman, T.K.

1981-01-01

Well placement is important in this area, as fractures are a principal source of water to wells. In areas of fractured bedrock, the most productive well locations are at the intersections of two or more mapped lineaments or fracture traces and at the lowest local altitude. Use of the lineament and fracture-trace map will not guarantee a sufficent supply of ground water but will minimize the chance of drilling an inadequate well.

An analysis of fracture trace patterns in areas of flat-lying sedimentary rocks for the detection of buried geologic structure. [Kansas and Texas

NASA Technical Reports Server (NTRS)

Podwysocki, M. H.

1974-01-01

Two study areas in a cratonic platform underlain by flat-lying sedimentary rocks were analyzed to determine if a quantitative relationship exists between fracture trace patterns and their frequency distributions and subsurface structural closures which might contain petroleum. Fracture trace lengths and frequency (number of fracture traces per unit area) were analyzed by trend surface analysis and length frequency distributions also were compared to a standard Gaussian distribution. Composite rose diagrams of fracture traces were analyzed using a multivariate analysis method which grouped or clustered the rose diagrams and their respective areas on the basis of the behavior of the rays of the rose diagram. Analysis indicates that the lengths of fracture traces are log-normally distributed according to the mapping technique used. Fracture trace frequency appeared higher on the flanks of active structures and lower around passive reef structures. Fracture trace log-mean lengths were shorter over several types of structures, perhaps due to increased fracturing and subsequent erosion. Analysis of rose diagrams using a multivariate technique indicated lithology as the primary control for the lower grouping levels. Groupings at higher levels indicated that areas overlying active structures may be isolated from their neighbors by this technique while passive structures showed no differences which could be isolated.

Characterisation of Fractures and Fracture Zones in a Carbonate Aquifer Using Electrical Resistivity Tomography and Pricking Probe Methodes

NASA Astrophysics Data System (ADS)

Szalai, Sandor; Kovacs, Attila; Kuslits, Lukács; Facsko, Gabor; Gribovszki, Katalin; Kalmar, Janos; Szarka, Laszlo

2018-04-01

Position, width and fragmentation level of fracture zones and position, significance and characteristic distance of fractures were aimed to determine in a carbonate aquifer. These are fundamental parameters, e.g. in hydrogeological modelling of aquifers, due to their role in subsurface water movements. The description of small scale fracture systems is however a challenging task. In the test area (Kádárta, Bakony Mts, Hungary), two methods proved to be applicable to get reasonable information about the fractures: Electrical Resistivity Tomography (ERT) and Pricking-Probe (PriP). PriP is a simple mechanical tool which has been successfully applied in archaeological investigations. ERT results demonstrated its applicability in this small scale fracture study. PriP proved to be a good verification tool both for fracture zone mapping and detecting fractures, but in certain areas, it produced different results than the ERT. The applicability of this method has therefore to be tested yet, although its problems most probably origin from human activity which reorganises the near-surface debris distribution. In the test site, both methods displayed fracture zones including a very characteristic one and a number of individual fractures and determined their characteristic distance and significance. Both methods prove to be able to produce hydrogeologically important parameters even individually, but their simultaneous application is recommended to decrease the possible discrepancies.

Geological Mapping Uses Landsat 4-5TM Satellite Data in Manlai Soum of Omnogovi Aimag

NASA Astrophysics Data System (ADS)

Norovsuren, B.

2014-12-01

Author: Bayanmonkh N1, Undram.G1, Tsolmon.R2, Ariunzul.Ya1, Bayartungalag B31 Environmental Research Information and Study Center 2NUM-ITC-UNESCO Space Science and Remote Sensing International Laboratory, National University of Mongolia 3Geology and Hydrology School, Korea University KEY WORDS: geology, mineral resources, fracture, structure, lithologyABSTRACTGeologic map is the most important map for mining when it does exploration job. In Mongolia geological map completed by Russian geologists which is done by earlier technology. Those maps doesn't satisfy for present requirements. Thus we want to study improve geological map which includes fracture, structural map and lithology use Landsat TM4-5 satellite data. If we can produce a geological map from satellite data with more specification then geologist can explain or read mineralogy very easily. We searched all methodology and researches of every single element of geological mapping. Then we used 3 different remote sensing methodologies to produce structural and lithology and fracture map based on geographic information system's softwares. There can be found a visible lithology border improvement and understandable structural map and we found fracture of the Russian geological map has a lot of distortion. The result of research geologist can read mineralogy elements very easy and discovered 3 unfound important elements from satellite image.

Development of Fracture Mechanics Maps for Composite Materials. Volume 3.

DTIC Science & Technology

1985-12-01

RD-At69 W4 DEVELOPMENT OF FRCTURE ECHNICS NPS FOR COMPOSITE V3jMATERIALS VOLUME 3( ) DEUTSCHE FORSCHUNOS- UND YERSUCHSANSTALT FUER LUFT- UND RAUMF...DEVELOPMENT OF FRACTURE MECHANICS MAPS I FOR COMPOSITE MATERIALS Dr. H. W. Bergmann DFVLR - Institute for Structural Mechanics Braunschweig, West Germany...Brussels, Belgium ELEMENT NO . NO. NO. NO. 11. TITLE (Include Security Classification) Development of N/A N/A N/A N/A Fracture MechanicsMaps for Composite

Application of ERTS-1 imagery to fracture related mine safety hazards in the coal mining industry. [Indiana

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J. (Principal Investigator); Russell, O. R.; Amato, R. V.; Leshendok, T. V.

1974-01-01

The author has identified the following significant results. New fracture detail of Indiana has been observed and mapped from ERTS-1 imagery. Studies so far indicate a close relationship between the directions of fracture traces mapped from the imagery, fractures measured on bedrock outcrops, and fractures measured in the underground mines. First hand observations and discussions with underground mine operators indicate good correlation of mine hazard maps prepared from ERTS-1/aircraft imagery and actual roof falls. The inventory of refuse piles/slurry ponds of the coal field of Indiana has identified over 225 such sites from past mining operations. These data will serve the State Legislature in making tax decisions on coal mining which take on increased importance because of the energy crisis.

Electromagnetic Measurements in an Active Oilfield Environment

NASA Astrophysics Data System (ADS)

Schramm, K. A.; Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Weiss, C. J.

2015-12-01

An important issue in oilfield development pertains to mapping and monitoring of the fracture distributions (either natural or man-made) controlling subsurface fluid flow. Although microseismic monitoring and analysis have been used for this purpose for several decades, there remain several ambiguities and uncertainties with this approach. We are investigating a novel electromagnetic (EM) technique for detecting and mapping hydraulic fractures in a petroleum reservoir by injecting an electrically conductive contrast agent into an open fracture. The fracture is subsequently illuminated by a strong EM field radiated by a large engineered antenna. Specifically, a grounded electric current source is applied directly to the steel casing of the borehole, either at/near the wellhead or at a deep downhole point. Transient multicomponent EM signals (both electric and magnetic) scattered by the conductivity contrast are then recorded by a surface receiver array. We are presently utilizing advanced 3D numerical modeling algorithms to accurately simulate fracture responses, both before and after insertion of the conductive contrast agent. Model results compare favorably with EM field data recently acquired in a Permian Basin oilfield. However, extraction of the very-low-amplitude fracture signatures from noisy data requires effective noise suppression strategies such as long stacking times, rejection of outliers, and careful treatment of natural magnetotelluric fields. Dealing with the ever-present "episodic EM noise" typical in an active oilfield environment (associated with drilling, pumping, machinery, traffic, etc.) constitutes an ongoing problem. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Autonomous microexplosives subsurface tracing system final report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew

The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping ofmore » subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.« less

Overview of microseismic monitoring of hydraulic fracturing for unconventional oil and gas plays

NASA Astrophysics Data System (ADS)

Shemeta, J. E.

2011-12-01

The exponential growth of unconventional resources for oil and gas production has been driven by the use of horizontal drilling and hydraulic fracturing. These drilling and completion methods increase the contact area of the low permeability and porosity hydrocarbon bearing formations and allow for economic production in what was previously considered uncommercial rock. These new resource plays have sparked an enormous interest in microseismic monitoring of hydraulic fracture treatments. As a hydraulic fracture is pumped, microseismic events are emitted in a volume of rock surrounding the stimulated fracture. The goal of the monitoring is to identify and locate the microseismic events to a high degree of precision and to map the position of the induced hydraulic fracture in time and space. The microseismic events are very small, typically having a moment-magnitude range of -4 to 0. The microseismic data are collected using a variety of seismic array designs and instrumentation, including borehole, shallow borehole, near-surface and surface arrays, using either of three-component clamped 15 Hz borehole sondes to simple vertical 10 Hz geophones for surface monitoring. The collection and processing of these data is currently under rapid technical development. Each monitoring method has technical challenges which include accurate velocity modeling, correct seismic phase identification and signal to noise issues. The microseismic locations are used to guide hydrocarbon exploration and production companies in crucial reservoir development decisions such as the direction to drill the horizontal well bores and the appropriate inter-well spacing between horizontal wells to optimally drain the resource. The fracture mapping is also used to guide fracture and reservoir engineers in designing and calibrating the fluid volumes and types, injection rates and pressures for the hydraulic fracture treatments. The microseismic data can be located and mapped in near real-time during an injection and used to assist the operators in the avoidance of geohazards (such as a karst feature or fault) or fracture height growth into undesirable formations such as water-bearing zones (that could ruin the well). An important objective for hydraulic fracture mapping is to map the effective fracture geometry: the specific volume of rock that is contributing to hydrocarbon flow in to the well. This, however, still remains an elusive goal that has yet to be completely understood with the current mapping technology.

Feature Detection in SAR Interferograms With Missing Data Displays Fault Slip Near El Mayor-Cucapah and South Napa Earthquakes

NASA Astrophysics Data System (ADS)

Parker, J. W.; Donnellan, A.; Glasscoe, M. T.; Stough, T.

2015-12-01

Edge detection identifies seismic or aseismic fault motion, as demonstrated in repeat-pass inteferograms obtained by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) program. But this identification, demonstrated in 2010, was not robust: for best results, it requires a flattened background image, interpolation into missing data (holes) and outliers, and background noise that is either sufficiently small or roughly white Gaussian. Proper treatment of missing data, bursting noise patches, and tiny noise differences at short distances apart from bursts are essential to creating an acceptably reliable method sensitive to small near-surface fractures. Clearly a robust method is needed for machine scanning of the thousands of UAVSAR repeat-pass interferograms for evidence of fault slip, landslides, and other local features: hand-crafted intervention will not do. Effective methods of identifying, removing and filling in bad pixels reveal significant features of surface fractures. A rich network of edges (probably fractures and subsidence) in difference images spanning the South Napa earthquake give way to a simple set of postseismically slipping faults. Coseismic El Mayor-Cucapah interferograms compared to post-seismic difference images show nearly disjoint patterns of surface fractures in California's Sonoran Desert; the combined pattern reveals a network of near-perpendicular, probably conjugate faults not mapped before the earthquake. The current algorithms for UAVSAR interferogram edge detections are shown to be effective in difficult environments, including agricultural (Napa, Imperial Valley) and difficult urban areas (Orange County.).

Development of Fracture Mechanics Maps for Composite Materials. Volume 2.

DTIC Science & Technology

1985-12-01

AD-A169 663 DEP 1/3UR OIOST l uNCL~ss~~n HUCI S I B M 11 1*2 AF,:P,.-TR-?5,-4150 DEVELOPMENT OF FRACTURE MECHANICS MAPS FOR COMPOSITE MATERIALS Dr. H...coIo. Development of N/A N/A N/A N/A Fracture Mechanics Maps for Composite Materials 12. PERSONAL AUTHORISI Editor (Dr. H. W. Bergmann) 13. TYPE OF...GROUP SUB GR. Fiber Reinforced Composites , Dynamic Test, Thermal Cycling, 1I1 04 Quality Control, Static Test, Stress Concentrations 01 03 19

Structural geology mapping using PALSAR data in the Bau gold mining district, Sarawak, Malaysia

NASA Astrophysics Data System (ADS)

Pour, Amin Beiranvand; Hashim, Mazlan

2014-08-01

The application of optical remote sensing data for geological mapping is difficult in the tropical environment. The persistent cloud coverage, dominated vegetation in the landscape and limited bedrock exposures are constraints imposed by the tropical climate. Structural geology investigations that are searching for epithermal or polymetallic vein-type ore deposits can be developed using Synthetic Aperture Radar (SAR) remote sensing data in tropical/sub-tropical regions. The Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo has been selected for this study. The Bau is a gold field similar to Carlin style gold deposits, but gold mineralization at Bau is much more structurally controlled. Geological analyses coupled with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) remote sensing data were used to detect structural elements associated with gold mineralization. The PALSAR data were used to perform lithological-structural mapping of mineralized zones in the study area and surrounding terrain. Structural elements were detected along the SSW to NNE trend of the Tuban fault zone and Tai Parit fault that corresponds to the areas of occurrence of the gold mineralization in the Bau Limestone. Most of quartz-gold bearing veins occur in high-angle faults, fractures and joints within massive units of the Bau Limestone. The results show that four deformation events (D1-D4) in the structures of the Bau district and structurally controlled gold mineralization indicators, including faults, joints and fractures are detectable using PALSAR data at both regional and district scales. The approach used in this study can be more broadly applicable to provide preliminary information for exploration potentially interesting areas of epithermal or polymetallic vein-type mineralization using the PALSAR data in the tropical/sub-tropical regions.

Land-Surface Subsidence and Open Bedrock Fractures in the Tully Valley, Onondaga County, New York

USGS Publications Warehouse

Hackett, William R.; Gleason, Gayle C.; Kappel, William M.

2009-01-01

Open bedrock fractures were mapped in and near two brine field areas in Tully Valley, New York. More than 400 open fractures and closed joints were mapped for dimension, orientation, and distribution along the east and west valley walls adjacent to two former brine fields. The bedrock fractures are as much as 2 feet wide and over 50 feet deep, while linear depressions in the soil, which are 3 to 10 feet wide and 3 to 6 feet deep, indicate the presence of open bedrock fractures below the soil. The fractures are probably the result of solution mining of halite deposits about 1,200 feet below the land surface.

Correlation of LANDSAT lineaments with Devonian gas fields in Lawrence County, Ohio

NASA Technical Reports Server (NTRS)

Johnson, G. O.

1981-01-01

In an effort to locate sources of natural gas in Ohio, the fractures and lineaments in Black Devonian shale were measured by: (1) field mapping of joints, swarms, and fractures; (2) stereophotointerpretation of geomorphic lineaments with precise photoquads; and (3) by interpreting the linear features on LANDSAT images. All results were compiled and graphically represented on 1:250,000 scale maps. The geologic setting of Lawrence County was defined and a field fracture map was generated and plotted as rose patterns at the exposure site. All maps were compared, contrasted, and correlated by superimposing each over the other as a transparency. The LANDSAT lineaments had significant correlation with the limits of oil and gas producing fields. These limits included termination of field production as well as extensions to other fields. The lineaments represent real rock fractures with zones of increased permeability in the near surface bedrock.

Study of the application of ERTS-A imagery to fracture-related mine safety hazards in the coal mining industry

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J. (Principal Investigator); Russell, O. R.; Amato, R. V.

1972-01-01

The author has identified the following significant results. Various data compilation and analysis activities in support of ERTS-1 imagery interpretation are in progress or are completed. These include the compilation of mine accident data, areas of mine roof instability and the analysis of high altitude color infrared photography and low altitude color and color infrared photography which was acquired by NASA in support of the project. The photography reveals that many fracture lineaments are detectable through a varied thickness of glacial till. These data will be compiled on a series of 1:250,000 scale base maps and evaluated for a correlation between fracture zones and mine accidents and rooffalls. Due to high occurrence of cloud cover in the project area and to the delay in imagery shipments, little progress has been made in the analysis of ERTS-1 imagery.

Mapping of hydraulic fractures from tiltmeter measurements

NASA Astrophysics Data System (ADS)

Lecampion, B.; Jeffrey, R.

2003-12-01

In considering the problem of inverse modeling of tiltmeter data for hydraulic fracture mapping, we address the issues of selecting the elastic model to represent the hydraulic fracture and limitations imposed by distance and fracture size on the information that can be recovered about the fracture. A tiltmeter measures, at its location, the changes in the surface inclination in two orthogonal directions. These inclinations are a direct measure of the horizontal gradient of the vertical component of the displacement field. Since advances in instrumentation in the last two decades, this type of apparatus have become extremely precise and can detect inclination changes down to a nanoradian. The simplicity of tiltmeter measurements has attracted interest not only in geophysics, but also in the petroleum industry. The idea of using tiltmeters to monitor hydraulic fractures can be traced back to the paper of Sun te{S} and is now a commercial service offered to the petroleum industry te{W}. However, the modeling and associated inverse problems required to analyze tiltmeter data raise difficult questions. The object(s) (fault, dyke, fracture) responsible for the recorded tilt are often modeled by finite Displacement Discontinuities, also called dislocation models. The validity of this type of model has been extensively discussed te{O,E} and many solutions for different configurations can be found in the literature. We show that it is possible to construct the solution for any type of dislocation model from the fundamental solution for an infinitesimal Displacement Discontinuity tensor. The eigenstrain theory te{M} is used to obtain this fundamental solution from the Green's function for the desired elastic domain (e.g. full or half space). Comparisons with known solutions demonstrate the flexibility of such method. We then focus on the problem of obtaining information about the orientation and size of an opening mode hydraulic fracture from the measured tilt field. One important problem is the identification of all the dimensions of the fracture model (length, width). The ability to obtain these parameters is controlled by limits, expressed in terms of the distance between the measurements and the fracture compared to the size of the fracture itself. The value of this ratio provides a condition that must be met before the fracture length-scales can be resolved. Determination of the fracture orientation is then investigated using a spatial Fourier Transform on the data set. This procedure highlights the requirement on the measurement array needed for a reliable identification: extension, number of tiltmeters, relative angle between the array and the fracture plane. \\begin{thebibliography}{1} \\bibitem{E} {Evans K.} \

Simple X-ray versus ultrasonography examination in blunt chest trauma: effective tools of accurate diagnosis and considerations for rib fractures.

PubMed

Hwang, Eun Gu; Lee, Yunjung

2016-12-01

Simple radiography is the best diagnostic tool for rib fractures caused by chest trauma, but it has some limitations. Thus, other tools are also being used. The aims of this study were to investigate the effectiveness of ultrasonography (US) for identifying rib fractures and to identify influencing factors of its effectiveness. Between October 2003 and August 2007, 201 patients with blunt chest trauma were available to undergo chest radiographic and US examinations for diagnosis of rib fractures. The two modalities were compared in terms of effectiveness based on simple radiographic readings and US examination results. We also investigated the factors that influenced the effectiveness of US examination. Rib fractures were detected on radiography in 69 patients (34.3%) but not in 132 patients. Rib fractures were diagnosed by using US examination in 160 patients (84.6%). Of the 132 patients who showed no rib fractures on radiography, 92 showed rib fractures on US. Among the 69 patients of rib fracture detected on radiography, 33 had additional rib fractures detected on US. Of the patients, 76 (37.8%) had identical radiographic and US results, and 125 (62.2%) had fractures detected on US that were previously undetected on radiography or additional fractures detected on US. Age, duration until US examination, and fracture location were not significant influencing factors. However, in the group without detected fractures on radiography, US showed a more significant effectiveness than in the group with detected fractures on radiography ( P =0.003). US examination could detect unnoticed rib fractures on simple radiography. US examination is especially more effective in the group without detected fractures on radiography. More attention should be paid to patients with chest trauma who have no detected fractures on radiography.

Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

DOE R&D Accomplishments Database

Poston, S. W.

1991-01-01

The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

A predictive penetrative fracture mapping method from regional potential field and geologic datasets, southwest Colorado Plateau, U.S.A

USGS Publications Warehouse

Gettings, M.E.; Bultman, M.W.

2005-01-01

Some aquifers of the southwest Colorado Plateau, U.S.A., are deeply buried and overlain by several impermeable units, and thus recharge to the aquifer is probably mainly by seepage down penetrative fracture systems. This purpose of this study was to develop a method to map the location of candidate deep penetrative fractures over a 120,000 km2 area using gravity and aeromagnetic anomaly data together with surficial fracture data. The resulting database constitutes a spatially registered estimate of recharge location. Candidate deep fractures were obtained by spatial correlation of horizontal gradient and analytic signal maxima of gravity and magnetic anomalies vertically with major surficial lineaments obtained from geologic, topographic, side-looking airborne radar, and satellite imagery. The maps define a sub-set of possible penetrative fractures because of limitations of data coverage and the analysis technique. The data and techniques employed do not yield any indication as to whether fractures are open or closed. Correlations were carried out using image processing software in such a way that every pixel on the resulting grids was coded to uniquely identify which datasets correlated. The technique correctly identified known deep fracture systems and many new ones. Maps of the correlations also define in detail the tectonic fabrics of the Southwestern Colorado Plateau. Copyright ?? The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.

Hydraulic tomography offers improved imaging of heterogeneity in fractured rocks.

PubMed

Illman, Walter A

2014-01-01

Fractured rocks have presented formidable challenges for accurately predicting groundwater flow and contaminant transport. This is mainly due to our difficulty in mapping the fracture-rock matrix system, their hydraulic properties and connectivity at resolutions that are meaningful for groundwater modeling. Over the last several decades, considerable effort has gone into creating maps of subsurface heterogeneity in hydraulic conductivity (K) and specific storage (Ss ) of fractured rocks. Developed methods include kriging, stochastic simulation, stochastic inverse modeling, and hydraulic tomography. In this article, I review the evolution of various heterogeneity mapping approaches and contend that hydraulic tomography, a recently developed aquifer characterization technique for unconsolidated deposits, is also a promising approach in yielding robust maps (or tomograms) of K and Ss heterogeneity for fractured rocks. While hydraulic tomography has recently been shown to be a robust technique, the resolution of the K and Ss tomograms mainly depends on the density of pumping and monitoring locations and the quality of data. The resolution will be improved through the development of new devices for higher density monitoring of pressure responses at discrete intervals in boreholes and potentially through the integration of other data from single-hole tests, borehole flowmeter profiling, and tracer tests. Other data from temperature and geophysical surveys as well as geological investigations may improve the accuracy of the maps, but more research is needed. Technological advances will undoubtedly lead to more accurate maps. However, more effort should go into evaluating these maps so that one can gain more confidence in their reliability. © 2013, National Ground Water Association.

Hydraulic tomography offers improved imaging of heterogeneity in fractured rocks

NASA Astrophysics Data System (ADS)

Illman, W. A.

2013-12-01

Fractured rocks have presented formidable challenges for accurately predicting groundwater flow and contaminant transport. This is mainly due to our difficulty in mapping the fracture-rock matrix system, their hydraulic properties and connectivity at resolutions that are meaningful for groundwater flow and especially transport modeling. Over the last several decades, considerable effort has gone into creating maps of subsurface heterogeneity in hydraulic conductivity (K) and specific storage (Ss) of fractured rocks. Developed methods include kriging, stochastic simulation, stochastic inverse modeling, and hydraulic tomography. In this presentation, I review the evolution of various heterogeneity mapping approaches and contend that hydraulic tomography, a recently developed aquifer characterization technique for unconsolidated deposits, is also a promising approach in yielding robust maps (or tomograms) of K and Ss heterogeneity for fractured rocks. While hydraulic tomography has recently been shown to be a robust technique, the resolution of the K and Ss tomograms mainly depends on the density of pumping and monitoring locations and the quality of data. The resolution will be improved through the development of new devices for higher density monitoring of pressure responses at discrete intervals in boreholes and potentially through the integration of other data from single-hole tests, borehole flowmeter profiling and tracer tests. Other data from temperature and geophysical surveys as well as geological investigations may improve the accuracy of the maps, but more research is needed. Technological advances will undoubtedly lead to more accurate maps. However, more effort should go into evaluating these maps so that one can gain more confidence in their reliability.

Modeling folding related multi-scale deformation of sedimentary rock using ALSM and fracture characterization at Raplee Ridge, UT

NASA Astrophysics Data System (ADS)

Mynatt, I.; Hilley, G. E.; Pollard, D. D.

2006-12-01

Understanding and predicting the characteristics of folding induced fracturing is an important and intriguing structural problem. Folded sequences of sedimentary rock at depth are common traps for hydrocarbons and water and fractures can strongly effect (both positively and negatively) this trapping capability. For these reasons fold-fracture relationships are well studied, but due to the complex interactions between the remote tectonic stress, rheologic properties, underlying fault geometry and slip, and pre-existing fractures, fracture characteristics can vary greatly from fold to fold. Additionally, examination of the relationships between fundamental characteristics such as fold geometry and fracture density are difficult even in thoroughly studied producing fields as measurements of fold shape are hampered by the low resolution of seismic surveying and measurements of fractures are limited to sparse well-bore locations. Due to the complexity of the system, the limitations of available data and small number of detailed case studies, prediction of fracture characteristics, e.g. the distribution of fracture density, are often difficult to make for a particular fold. We suggest a combination of mechanical and numerical modeling and analysis combined with detailed field mapping can lead to important insights into fold-fracture relationships. We develop methods to quantify both fold geometry and fracture characteristics, and summarize their relationships for an exhumed analogue reservoir case study. The field area is Raplee Monocline, a Laramide aged, N-S oriented, ~14-km long fold exposed in the Monument Upwarp of south-eastern Utah and part of the larger Colorado Plateau geologic province. The investigation involves three distinct parts: 1) Field based characterization and mapping of the fractures on and near the fold; 2) Development of accurate models of the fold geometry using high resolution data including ~3.5x107 x, y, z topographic points collected using Airborne Laser Swath Mapping (ALSM); and 3) Analysis of the fold shape and fracture patterns using the concepts of differential geometry and fracture mechanics. Field documentation of fracture characteristics enables the classification of distinct pre- and syn- folding fracture sets and the development of conceptual models of multiple stages of fracture evolution. Numerical algorithms, visual methods and field mapping techniques are used to extract the geometry of specific stratigraphic bedding surfaces and interpolate fold geometry between topographic exposures, thereby creating models of the fold geometry at several stratigraphic levels. Geometric characteristics of the fold models, such as magnitudes and directions of maximum and minimum normal curvature and fold limb dip, are compared to the observed fracture characteristics to identify the following relationships: 1) Initiation of folding related fractures at ten degrees of limb dip and increasing fracture density with increasing dip and 2) No correlation between absolute maximum fold curvature and fracture density.

Numerical Simulation of Callus Healing for Optimization of Fracture Fixation Stiffness

PubMed Central

Steiner, Malte; Claes, Lutz; Ignatius, Anita; Simon, Ulrich; Wehner, Tim

2014-01-01

The stiffness of fracture fixation devices together with musculoskeletal loading defines the mechanical environment within a long bone fracture, and can be quantified by the interfragmentary movement. In vivo results suggested that this can have acceleratory or inhibitory influences, depending on direction and magnitude of motion, indicating that some complications in fracture treatment could be avoided by optimizing the fixation stiffness. However, general statements are difficult to make due to the limited number of experimental findings. The aim of this study was therefore to numerically investigate healing outcomes under various combinations of shear and axial fixation stiffness, and to detect the optimal configuration. A calibrated and established numerical model was used to predict fracture healing for numerous combinations of axial and shear fixation stiffness under physiological, superimposed, axial compressive and translational shear loading in sheep. Characteristic maps of healing outcome versus fixation stiffness (axial and shear) were created. The results suggest that delayed healing of 3 mm transversal fracture gaps will occur for highly flexible or very rigid axial fixation, which was corroborated by in vivo findings. The optimal fixation stiffness for ovine long bone fractures was predicted to be 1000–2500 N/mm in the axial and >300 N/mm in the shear direction. In summary, an optimized, moderate axial stiffness together with certain shear stiffness enhances fracture healing processes. The negative influence of one improper stiffness can be compensated by adjustment of the stiffness in the other direction. PMID:24991809

Numerical simulation of callus healing for optimization of fracture fixation stiffness.

PubMed

Steiner, Malte; Claes, Lutz; Ignatius, Anita; Simon, Ulrich; Wehner, Tim

2014-01-01

The stiffness of fracture fixation devices together with musculoskeletal loading defines the mechanical environment within a long bone fracture, and can be quantified by the interfragmentary movement. In vivo results suggested that this can have acceleratory or inhibitory influences, depending on direction and magnitude of motion, indicating that some complications in fracture treatment could be avoided by optimizing the fixation stiffness. However, general statements are difficult to make due to the limited number of experimental findings. The aim of this study was therefore to numerically investigate healing outcomes under various combinations of shear and axial fixation stiffness, and to detect the optimal configuration. A calibrated and established numerical model was used to predict fracture healing for numerous combinations of axial and shear fixation stiffness under physiological, superimposed, axial compressive and translational shear loading in sheep. Characteristic maps of healing outcome versus fixation stiffness (axial and shear) were created. The results suggest that delayed healing of 3 mm transversal fracture gaps will occur for highly flexible or very rigid axial fixation, which was corroborated by in vivo findings. The optimal fixation stiffness for ovine long bone fractures was predicted to be 1000-2500 N/mm in the axial and >300 N/mm in the shear direction. In summary, an optimized, moderate axial stiffness together with certain shear stiffness enhances fracture healing processes. The negative influence of one improper stiffness can be compensated by adjustment of the stiffness in the other direction.

Characterization of Hydraulic Fractures Growth During the Äspö Hard Rock Laboratory Experiment (Sweden)

NASA Astrophysics Data System (ADS)

López-Comino, J. A.; Cesca, S.; Heimann, S.; Grigoli, F.; Milkereit, C.; Dahm, T.; Zang, A.

2017-11-01

A crucial issue to characterize hydraulic fractures is the robust, accurate and automated detection and location of acoustic emissions (AE) associated with the fracture nucleation and growth process. Waveform stacking and coherence analysis techniques are here adapted using massive datasets with very high sampling (1 MHz) from a hydraulic fracturing experiment that took place 410 m below surface in the Äspö Hard Rock Laboratory (Sweden). We present the results obtained during the conventional, continuous water injection experiment Hydraulic Fracture 2. The resulting catalogue is composed of more than 4000 AEs. Frequency-magnitude distribution from AE magnitudes (MAE) reveals a high b value of 2.4. The magnitude of completeness is also estimated approximately MAE 1.1, and we observe an interval range of MAE between 0.77 and 2.79. The hydraulic fractures growth is then characterized by mapping the spatiotemporal evolution of AE hypocentres. The AE activity is spatially clustered in a prolate ellipsoid, resembling the main activated fracture volume ( 105 m3), where the lengths of the principal axes ( a = 10 m; b = 5 m; c = 4 m) define its size and its orientation can be estimated for a rupture plane (strike 123°, dip 60°). An asymmetric rupture process regarding to the fracturing borehole is clearly exhibited. AE events migrate upwards covering the depth interval between 404 and 414 m. After completing each injection and reinjection phase, the AE activity decreases and appears located in the same area of the initial fracture phase, suggesting a crack-closing effect.

Electromagnetic (EM) earthquake precursor transmission and detection regarding experimental field and laboratory results.

NASA Astrophysics Data System (ADS)

Jones, Kenneth B., II; Saxton, Patrick

2016-04-01

Aside from understanding the animal kingdom reacting to a per-earthquake signal, a transmission source is apparent. The focus of this investigation is an electromagnetic emission approach and detection capable of becoming both practical and reliable to other plausible earthquake precursors. To better determine this method, several prototype magnetometers were devised and built with each successive version improving upon the next. Two twin (prototype #2) antennae were deployed to field settings outside the NE Texas town of Timpson, TX back in February, 2013 and very recent laboratory tests using the most refined (prototype #4) experimental antenna for detecting unconfined, granitic block fracturing. Field testing encompassed the small NE Texas town of Timpson, TX, which endured an earthquake phenomenon (May, 2012 - September, 2013). A rare sequence of events was strictly attributed to hydraulic fracturing activity in the immediate area all for hydrocarbon capture; thus, a chance to detect and record man-made earthquake activity. By swiveling two directional antennae at three locations, one mobile, the antennae could 'zero' in on a signal source until its pattern was well established and mapped, accordingly. Three signals were detected, two strong and one moderately strong, each with epicenter implications several kilometers from known seismological sites. Six months later, two M4s and a M2.4 earthquake hit over the 2013 Labor Day weekend. Hydraulic pump pressure increased deep Earth pore pressure, reduced friction, and displaced opposing tectonic stresses causing rock to fracture. This was the last earthquake sequence in the Timpson area, due to personal involvement and area citizens in contact with their state representatives. Well and drilling operations have since moved 40-50 miles SE of Timpson, TX and rare earthquake activity has now occurred there. Laboratory testing was next performed using cored granitic blocks and the latest, improved antenna with an increased, variable geometry. The blocks were all successfully fractured with expansionary cement netting consecutive and identical EM emission results very similar to the Timpson pre-earthquake results. Cored granite made up the largest amount of rock test types, due to the large volume occurring as basement rock. EM transmission in the ELF range ascending from depth was theorized to follow paths of least resistance via faults and other fracture spaces than actual penetration through solid rock, which may attenuate both signal strength and frequency response. Fault geometry, fracture orientation/termination, and subsurface reflection may make epicenter determinations problematic; however, EM emissions will continually occur and be detectable with further signal analyses in refining epicentral locations.

Modeling a Shallow Rock Tunnel Using Terrestrial Laser Scanning and Discrete Fracture Networks

NASA Astrophysics Data System (ADS)

Cacciari, Pedro Pazzoto; Futai, Marcos Massao

2017-05-01

Discontinuity mapping and analysis are extremely important for modeling shallow tunnels constructed in fractured rock masses. However, the limited exposure and variability of rock face orientation in tunnels must be taken into account. In this paper, an automatic method is proposed to generate discrete fracture networks (DFNs) using terrestrial laser scanner (TLS) geological mapping and to continuously calculate the volumetric intensities ( P 32) along a tunnel. The number of fractures intersecting rectangular sampling planes with different orientations, fitted in tunnel sections of finite lengths, is used as the program termination criteria to create multiple DFNs and to calculate the mean P 32. All traces and orientations from three discontinuity sets of the Monte Seco tunnel (Vitória Minas Railway) were mapped and the present method applied to obtain the continuous variation in P 32 along the tunnel. A practical approach to creating single and continuous DFNs (for each discontinuity set), considering the P 32 variations, is also presented, and the results are validated by comparing the trace intensities ( P 21) from the TLS mapping and DFNs generated. Three examples of 3DEC block models generated from different sections of the tunnel are shown, including the ground surface and the bedrock topographies. The results indicate that the proposed method is a practical and powerful tool for modeling fractured rock masses of uncovered tunnels. It is also promising for application during tunnel construction when TLS mapping is a daily task (for as-built tunnel controls), and the complete geological mapping (traces and orientations) is available.

Probabilistic landslide susceptibility mapping in the Lai Chau province of Vietnam: focus on the relationship between tectonic fractures and landslides

NASA Astrophysics Data System (ADS)

Lee, Saro; Dan, Nguyen Tu

2005-09-01

This study evaluates the susceptibility of landslides in the Lai Chau province of Vietnam using Geographic Information System (GIS) and remote sensing data to focus on the relationship between tectonic fractures and landslides. Landslide locations were identified from aerial photographs and field surveys. Topographic, geological data and satellite images were collected, processed, and constructed into a spatial database using GIS data and image-processing techniques. A scheme of the tectonic fracturing of crust in the Lai Chau region was established. Lai Chau was identified as a region with many crustal fractures, where the grade of tectonic fracture is closely related to landslide occurrence. The influencing factors of landslide occurrence were: distance from a tectonic fracture, slope, aspect, curvature, soil, and vegetative land cover. Landslide prone areas were analyzed and mapped using the landslide occurrence factors employing the probability-frequency ratio model. The results of the analysis were verified using landslide location data and showed 83.47% prediction accuracy. That emphasized a strong relationship between the susceptibility map and the existing landslide location data. The results of this study can form a basis stable development and land use planning for the region.

Development of a Neutron Diffraction Based Experiemental Capability for Investigating Hydraulic Fracturing for EGS-like Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polsky, Yarom; Anovitz, Lawrence; An, Ke

2013-01-01

Hydraulic fracturing to enhance formation permeability is an established practice in the Oil & Gas (O&G) industry and is expected to be an enabler for EGS. However, it is rarely employed in conventional geothermal systems and there are significant questions regarding the translation of practice from O&G to both conventional geothermal and EGS applications. Lithological differences(sedimentary versus crystalline rocks, significantly greater formation temperatures and different desired fracture characteristics are among a number of factors that are likely to result in a gap of understanding of how to manage hydraulic fracturing practice for geothermal. Whereas the O&G community has had bothmore » the capital and the opportunity to develop its understanding of hydraulic fracturing operations empirically in the field as well through extensive R&D efforts, field testing opportunities for EGS are likely to be minimal due to the high expense of hydraulic fracturing field trials. A significant portion of the knowledge needed to guide the management of geothermal/EGS hydraulic fracturing operations will therefore likely have to come from experimental efforts and simulation. This paper describes ongoing efforts at Oak Ridge National Laboratory (ORNL) to develop an experimental capability to map the internal stresses/strains in core samples subjected to triaxial stress states and temperatures representative of EGS-like conditions using neutron diffraction based strain mapping techniques. This capability is being developed at ORNL\\'s Spallation Neutron Source, the world\\'s most powerful pulsed neutron source and is still in a proof of concept phase. A specialized pressure cell has been developed that permits independent radial and axial fluid pressurization of core samples, with axial flow through capability and a temperature rating up to 300 degrees C. This cell will ultimately be used to hydraulically pressurize EGS-representative core samples to conditions of imminent fracture and map the associated internal strain states of the sample. This will hopefully enable a more precise mapping of the rock material failure envelope, facilitate a more refined understanding of the mechanism of hydraulically induced rock fracture, particularly in crystalline rocks, and serve as a platform for validating and improving fracture simulation codes. The elements of the research program and preliminary strain mapping results of a Sierra White granite sample subjected only to compressive loading will be discussed in this paper.« less

Fracture trace map and single-well aquifer test results in a carbonate aquifer in Berkeley County, West Virginia

USGS Publications Warehouse

McCoy, Kurt J.; Podwysocki, Melvin H.; Crider, E. Allen; Weary, David J.

2005-01-01

These data contain information on the results of single-well aquifer tests, lineament analysis, and a bedrock geologic map compilation for the low-lying carbonate and shale areas of eastern Berkeley County, West Virginia. Efforts have been initiated by management agencies of Berkeley County in cooperation with the U.S. Geological Survey to further the understanding of the spatial distribution of fractures in the carbonate regions and their correlation with aquifer properties. This report presents transmissivity values from about 200 single-well aquifer tests and a map of fracture-traces determined from aerial photos and field investigations. Transmissivity values were compared to geologic factors possibly affecting its magnitude.

Structural heritage, reactivation and distribution of fault and fracture network in a rifting context: Case study of the western shoulder of the Upper Rhine Graben

NASA Astrophysics Data System (ADS)

Bertrand, Lionel; Jusseaume, Jessie; Géraud, Yves; Diraison, Marc; Damy, Pierre-Clément; Navelot, Vivien; Haffen, Sébastien

2018-03-01

In fractured reservoirs in the basement of extensional basins, fault and fracture parameters like density, spacing and length distribution are key properties for modelling and prediction of reservoir properties and fluids flow. As only large faults are detectable using basin-scale geophysical investigations, these fine-scale parameters need to be inferred from faults and fractures in analogous rocks at the outcrop. In this study, we use the western shoulder of the Upper Rhine Graben as an outcropping analogue of several deep borehole projects in the basement of the graben. Geological regional data, DTM (Digital Terrain Model) mapping and outcrop studies with scanlines are used to determine the spatial arrangement of the faults from the regional to the reservoir scale. The data shows that: 1) The fault network can be hierarchized in three different orders of scale and structural blocks with a characteristic structuration. This is consistent with other basement rocks studies in other rifting system allowing the extrapolation of the important parameters for modelling. 2) In the structural blocks, the fracture network linked to the faults is linked to the interplay between rock facies variation linked to the rock emplacement and the rifting event.

Guidelines for Proof Test Analysis

NASA Technical Reports Server (NTRS)

Chell, G. G.; McClung, R. C.; Kuhlman, C. J.; Russell, D. A.; Garr, K.; Donnelly, B.

1999-01-01

These guidelines integrate state-of-the-art elastic-plastic fracture mechanics (EPFM) and proof test implementation issues into a comprehensive proof test analysis procedure in the form of a road map which identifies the types of data, fracture mechanics based parameters, and calculations needed to perform flaw screening and minimum proof load analyses of fracture critical components. Worked examples are presented to illustrate the application of the road map to proof test analysis. The state-of-the art fracture technology employed in these guidelines is based on the EPFM parameter, J, and a pictorial representation of a J fracture analysis, called the failure assessment diagram (FAD) approach. The recommended fracture technology is validated using finite element J results, and laboratory and hardware fracture test results on the nickel-based superalloy Inconel 718, the aluminum alloy 2024-T3511, and ferritic pressure vessel steels. In all cases the laboratory specimens and hardware failed by ductile mechanisms. Advanced proof test analyses involving probability analysis and multiple-cycle proof testing (MCPT) are addressed. Finally, recommendations are provided on how to account for the effects of the proof test overload on subsequent service fatigue and fracture behaviors.

Mapping Surface Features Produced by an Active Landslide

NASA Astrophysics Data System (ADS)

Parise, Mario; Gueguen, Erwan; Vennari, Carmela

2016-10-01

A large landslide reactivated on December 2013, at Montescaglioso, southern Italy, after 56 hours of rainfall. The landslide disrupted over 500 m of a freeway, involved a few warehouses, a supermarket, and private homes. After the event, it has been performed field surveys, aided by visual analysis of terrestrial and helicopter photographs, to compile a map of the surface deformations. The geomorphological features mapped included single fractures, sets of fractures, tension cracks, trenches, and pressure ridges. In this paper we present the methodology used, the map obtained through the intensive field work, and discuss the main surface features produced by the landslide.

Geologic Mapping of the V-36 Thetis Regio Quadrangle: 2008 Progress Report

NASA Technical Reports Server (NTRS)

Basilevsky, A. T.; Head, James W.

2008-01-01

As a result of mapping, eleven material stratigraphic units and three structural units have been identified and mapped. The material units include (from older to younger): tessera terrain material (tt), material of densely fractured plains (pdf), material of fractured and ridged plains (pfr), material of shield plains (psh), material of plains with wrinkle ridges (pwr), material of smooth plains of intermediate brightness (psi), material of radardark smooth plains (psd), material of lineated plains (pli) material of lobate plains (plo), material of craters having no radar-dark haloes (c1), and material of craters having clear dark haloes (c2). The morphologies and probably the nature of the material units in the study area are generally similar to those observed in other regions of Venus [2]. The youngest units are lobate plains (plo) which here typically look less lobate than in other areas of the planet. Close to them in age are smooth plains which are indeed smooth and represented by two varieties mentioned above. Lineated plains (pli) are densely fractured in a geometrically regular way. Plains with wrinkle ridges, being morphologically similar to those observed in other regions, here occupy unusually small areas. Shield (psh) plains here are also not abundant. Locally they show wrinkle ridging. Fractured and ridged plains (pfr), which form in other regions, the so called ridge belts, are observed as isolated areas of clusters of ridged plains surrounded by other units. Densely fractured plains (pdf) are present in relatively small areas in association with coronae and corona-like features. Tessera terrain (tt) is dissected by structures oriented in two or more directions. Structures are so densely packed that the morphology (and thus nature) of the precursor terrain is not known. Structural units include tessera transitional terrain (ttt), fracture belts (fb) and rifted terrain (rt). Tessera transitional terrain was first identified and mapped by [4] as areas of fractured and ridged plains (pfr) and densely fractured plains (pdf) deformed by transverse faults that made it formally resemble tessera terrain (tt). The obvious difference between units tt and ttt is the recognizable morphology of precursor terrain of unit ttt. Fracture belts are probably ancient rift zones [3]. Rifted terrain (rt), as in other regions of Venus, is so saturated with faults that according to the recommendation of [1, 5] it should be mapped as a structural unit.

Computerized method for detection of vertebral fractures on lateral chest radiographs based on morphometric data

NASA Astrophysics Data System (ADS)

Kasai, Satoshi; Li, Feng; Shiraishi, Junji; Li, Qiang; Straus, Christopher; Vokes, Tamara; MacMahon, Heber; Doi, Kunio

2007-03-01

Vertebral fractures are the most common osteoporosis-related fractures. It is important to detect vertebral fractures, because they are associated with increased risk of subsequent fractures, and because pharmacologic therapy can reduce the risk of subsequent fractures. Although vertebral fractures are often not clinically recognized, they can be visualized on lateral chest radiographs taken for other purposes. However, only 15-60% of vertebral fractures found on lateral chest radiographs are mentioned in radiology reports. The purpose of this study was to develop a computerized method for detection of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation. Our computerized method is based on the automated identification of upper and lower vertebral edges. In order to develop the scheme, radiologists provided morphometric data for each identifiable vertebra, which consisted of six points for each vertebra, for 25 normals and 20 cases with severe fractures. Anatomical information was obtained from morphometric data of normal cases in terms of vertebral heights, heights of vertebral disk spaces, and vertebral centerline. Computerized detection of vertebral fractures was based on the reduction in the heights of fractured vertebrae compared to adjacent vertebrae and normal reference data. Vertebral heights from morphometric data on normal cases were used as reference. On 138 chest radiographs (20 with fractures) the sensitivity of our method for detection of fracture cases was 95% (19/20) with 0.93 (110/118) false-positives per image. In conclusion, the computerized method would be useful for detection of potentially overlooked vertebral fractures on lateral chest radiographs.

Correlative fractography: combining scanning electron microscopy and light microscopes for qualitative and quantitative analysis of fracture surfaces.

PubMed

Hein, Luis Rogerio de Oliveira; de Oliveira, José Alberto; de Campos, Kamila Amato

2013-04-01

Correlative fractography is a new expression proposed here to describe a new method for the association between scanning electron microscopy (SEM) and light microscopy (LM) for the qualitative and quantitative analysis of fracture surfaces. This article presents a new method involving the fusion of one elevation map obtained by extended depth from focus reconstruction from LM with exactly the same area by SEM and associated techniques, as X-ray mapping. The true topographic information is perfectly associated to local fracture mechanisms with this new technique, presented here as an alternative to stereo-pair reconstruction for the investigation of fractured components. The great advantage of this technique resides in the possibility of combining any imaging methods associated with LM and SEM for the same observed field from fracture surface.

The anterior tilt angle of the proximal tibia epiphyseal plate: a significant radiological finding in young children with trampoline fractures.

PubMed

Stranzinger, Enno; Leidolt, Lars; Eich, Georg; Klimek, Peter Michael

2014-08-01

Evaluation of the anterior tilt angle of the proximal tibia epiphyseal plate in young children, which suffered a trampoline fracture in comparison with a normal population. 62 children (31 females, 31 males) between 2 and 5 years of age (average 2 years 11 months, standard deviation 11 months) with radiographs in two views of the tibia were included in this retrospective study. 25 children with proximal tibia fractures were injured with a history of jumping on a trampoline. All other causes for tibia fractures were excluded. A normal age-mapped control cohort of 37 children was compared. These children had neither evidence of a trampoline related injury nor a fracture of the tibia. The anterior tilt angle of the epiphyseal plate of the tibia was defined as an angle between the proximal tibia physis and the distal tibia physis on a lateral view. Two radiologists evaluated all radiographs for fractures and measured the anterior tilt angle in consensus. An unpaired Student's t-test was used for statistical analysis (SPSS). Original reports were reviewed and compared with the radiological findings and follow-up radiographs. In the normal control group, the average anterior tilt angle measured -3.2°, SD ± 2.8°. The children with trampoline fractures showed an anterior tilt of +4.4°, SD ± 2.9°. The difference was statistically significant, P<0.0001. In 6 patients (24% of all patients with confirmed fractures) the original report missed to diagnose the proximal tibial fracture. Young children between 2 and 5 years of age are at risk for proximal tibia fractures while jumping on a trampoline. These fractures may be very subtle and difficult to detect on initial radiographs. Measurement of the anterior tilt angle of the proximal tibia epiphyseal plate on lateral radiographs is supportive for interpreting correctly trampoline fractures. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Computerized detection of vertebral compression fractures on lateral chest radiographs: Preliminary results with a tool for early detection of osteoporosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasai, Satoshi; Li Feng; Shiraishi, Junji

Vertebral fracture (or vertebral deformity) is a very common outcome of osteoporosis, which is one of the major public health concerns in the world. Early detection of vertebral fractures is important because timely pharmacologic intervention can reduce the risk of subsequent additional fractures. Chest radiographs are used routinely for detection of lung and heart diseases, and vertebral fractures can be visible on lateral chest radiographs. However, investigators noted that about 50% of vertebral fractures visible on lateral chest radiographs were underdiagnosed or under-reported, even when the fractures were severe. Therefore, our goal was to develop a computerized method for detectionmore » of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation and thus allow the early diagnosis of osteoporosis. The cases used in this study were 20 patients with severe vertebral fractures and 118 patients without fractures, as confirmed by the consensus of two radiologists. Radiologists identified the locations of fractured vertebrae, and they provided morphometric data on the vertebral shape for evaluation of the accuracy of detecting vertebral end plates by computer. In our computerized method, a curved search area, which included a number of vertebral end plates, was first extracted automatically, and was straightened so that vertebral end plates became oriented horizontally. Edge candidates were enhanced by use of a horizontal line-enhancement filter in the straightened image, and a multiple thresholding technique, followed by feature analysis, was used for identification of the vertebral end plates. The height of each vertebra was determined from locations of identified vertebral end plates, and fractured vertebrae were detected by comparison of the measured vertebral height with the expected height. The sensitivity of our computerized method for detection of fracture cases was 95% (19/20), with 1.03 (139/135) false-positive fractures per image. The accuracy of identifying vertebral end plates, marked by radiologists in a morphometric study, was 76.6% (400/522) and 70.9% (420/592) for cases used for training and those for testing, respectively. We prepared 32 additional fracture cases for a validation test, and we examined the detection accuracy of our computerized method. The sensitivity for these cases was 75% (24/32) at 1.03 (33/32) false-positive fractures per image. Our preliminary results show that the automated computerized scheme for detecting vertebral fractures on lateral chest radiographs has the potential to assist radiologists in detecting vertebral fractures.« less

[Analysis of 163 rib fractures by imaging examination].

PubMed

Song, Tian-fu; Wang, Chao-chao

2014-12-01

To explore the applications of imaging examination on rib fracture sites in forensic identification. Features including the sites, numbers of the processed imaging examination and the first radiological technology at diagnosis in 56 cases of rib fractures from 163 injuries were retrospectively analyzed. The detection rate of the rib fractures within 14 days was 65.6%. The initial detection rate of anterior rib fracture proceeded by X-ray was 76.2%, then 90.5% detected at a second time X-ray, while the detection rate of CT was 66.7% and 80.0%, respectively. The initial detec- tion rate of rib fracture in axillary section proceeded by X-ray was 27.6%, then 58.6% detected at a second time X-ray, while the detection rate of CT was 54.3% and 80.4%, respectively. The initial detection rate of posterior rib fracture proceeded by X-ray was 63.6%, then 81.8% detected at a second time X-ray, while the detection rate of CT was 50.0% and 70.0%, respectively. It is important to pay attention to the use of combined imaging examinations and the follow-up results. In the cases of suspicious for rib fracture in axillary section, CT examination is suggested in such false X-ray negative cases.

Hydrogeologic controls on ground-water discharge to the Washington METRO subway tunnel near the Medical Center station and Crossover, Montgomery County, Maryland

USGS Publications Warehouse

Greene, Earl A.; Shapiro, Allen M.; LaMotte, Andrew E.

2004-01-01

Excessive water intrusion has been observed inside several of the Washington Metropolitan Area Transit Authority subway tunnels, with the worst leakage occurring along the Red Line tunnels and stations north of Dupont Circle in Washington, D.C. These tunnels were constructed in bedrock that contains permeable (water-bearing) joints and fractures. Excessive water leakage through the walls and water inside the underground facilities has damaged mechanical and electrical components in the tunnel, and has escalated the deterioration rate of the rail system. The U.S. Geological Survey and the Washington Metropolitan Area Transit Authority have worked cooperatively on a study from 200003 to describe and quantify the factors controlling ground-water flow into the Red Line subway tunnel near the Medical Center Station and Crossover in Montgomery County, Maryland. The Red Line near the Medical Center Station and Crossover passes through or beneath the gneissic Sykesville Formation and the biotite-hornblende tonalite member of the Georgetown Intrusive Suite, both of which contain numerous fractures. The mapped foliation and joints of the Sykesville Formation in the vicinity of the Medical Center Station and Crossover are generally orientated north-south. Fractures in the Sykesville Formation in outcrops appear to be poorly connected. In the biotite-hornblende tonalite member of the Georgetown Intrusive Suite, the general orientation of the mapped foliation and joints is east-west. In contrast to the fractures in the Sykesville Formation, the fractures in the Georgetown Intrusive Suite in outcrops appear to be more numerous and have a greater degree of connectivity. Fractures intersecting four bedrock wells near the Medical Center Station and Crossover that were drilled into the biotite-hornblende tonalite member of the Georgetown Intrusive Suite show an east-west orientation matching the foliation and joints shown on geologic maps. The excessive water intrusion at the Medical Center Station and Crossover could be the result of its location within the Georgetown Intrusive Suite. The abrupt changes in the mapped directions of ground-water flow based on the hydraulic heads at the contact between the Sykesville Formation and biotite-hornblende tonalite member of the Georgetown Intrusive Suite could also be the result of the change in fracturing between these two lithologies. Saprolite, a residual of soft, red/brown to gray clay from decomposed crystalline rock, overlies the bedrock and varies from about 20 to 55 feet thick, depending on location. On the basis of a slug test conducted in the lower part of the saprolite near the Medical Center Station and Crossover, transmissivity and storativity of the saprolite were estimated to be 10 feet squared per day and 10-6 , respectively. The transmissivity of fractures intersecting bedrock boreholes drilled in the biotite-hornblende tonalite member of the Georgetown Intrusive Suite varies over five orders of magnitude, from a maximum of approximately 10 feet squared per day to the detection limit of the in situ testing apparatus, which is approximately 10-4 feet squared per day. In general, the transmissivity of fractures intersecting the boreholes increases with depth. The low transmissivity of bedrock fractures in close proximity to the saprolite is likely to be caused by the fractures being filled with byproducts of rock weathering, resulting in reduced permeability. 2 Hydrogeologic Controls on Ground-Water Discharge to the Washington METRO Subway Tunnel The bulk transmissivity of the bedrock aquifer is approximately 3.7 feet squared per day, as determined from an aquifer test conducted by pumping a 240-foot-deep borehole and monitoring the drawdown over 3 days in the pumped borehole and several observation boreholes. In general, the hydraulic head decreases with depth in bedrock boreholes, indicating the potential for downward ground-water flow. Based on hydraulic head values mea

Prediction of fracture profile using digital image correlation

NASA Astrophysics Data System (ADS)

Chaitanya, G. M. S. K.; Sasi, B.; Kumar, Anish; Babu Rao, C.; Purnachandra Rao, B.; Jayakumar, T.

2015-04-01

Digital Image Correlation (DIC) based full field strain mapping methodology is used for mapping strain on an aluminum sample subjected to tensile deformation. The local strains on the surface of the specimen are calculated at different strain intervals. Early localization of strain is observed at a total strain of 0.050ɛ; itself, whereas a visually apparent localization of strain is observed at a total strain of 0.088ɛ;. Orientation of the line of fracture (12.0°) is very close to the orientation of locus of strain maxima (11.6°) computed from the strain mapping at 0.063ɛ itself. These results show the efficacy of the DIC based method to predict the location as well as the profile of the fracture, at an early stage.

EM Earthquake Precursor Detection Associated with Fluid Injection for Hydraulic Fracturing and Tectonic Sources

NASA Astrophysics Data System (ADS)

Jones, Kenneth B., II

2015-04-01

Many attempts have been made to determine an earthquake forecasting method and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic wave model, various hypotheses were formed, but only two seemed to take shape with the most interesting one requiring a magnetometer of a unique design. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, results have had wide variability and problems still reside with what exactly is forecastable and the investigative direction of a true precursor. After a number of custom rock experiments, the two hypotheses were thoroughly tested to correlate the EM wave model. The first hypothesis involved sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio wave generation. The second hypothesis resulted best with highly reproducible data, radio wave generation and detection, and worked numerous times with each laboratory test administered. In addition, internally introduced force on a small scale stressed a number of select rock types to emit radio waves well before catastrophic failure, and failure always went to completion. Comparatively, at a larger scale, highly detailed studies were procured to establish legitimate wave guides from potential hypocenters to epicenters and map the results, accordingly. Field testing in Southern California from 2006 to 2011 and outside the NE Texas town of Timpson in February, 2013 was conducted for detecting similar, laboratory generated, radio wave sources. At the Southern California field sites, signals were detected in numerous directions with varying amplitudes; therefore, a reactive approach was investigated in hopes of detecting possible aftershocks from large, tectonically related M5.0+ earthquakes. At the Timpson, Texas field sites, a proactive detection approach was taken, due to the heavy presence of hydraulic fracturing activity for regional hydrocarbon extraction, which appeared to be causing several rare M4.0+ earthquakes. As a result, detailed Southern California and Timpson, Texas field studies led to the improved design of two newer, prototype antennae and the first ever earthquake epicenter map. With more antennae and continuous monitoring, more fracture cycles can be established well ahead of the next earthquake. In addition, field data could be ascertained longer by the proper authorities and lead to significantly improved earthquake forecasting. The EM precursor determined by this method appears to surpass all prior precursor claims, and the general public may finally receive long overdue forecasting.

Hydrogeological investigation at Site 5, Willow Grove Naval Air Station/Joint Reserve Base, Horsham Township, Montgomery County, Pennsylvania

USGS Publications Warehouse

Sloto, Ronald A.

2002-01-01

The U.S. Geological Survey conducted borehole geophysical logging, collected and analyzed water-level data, and sampled sections of a rock core to determine the concentration of volatile organic compounds in the aquifer matrix of the Stockton Formation. Borehole geophysical logs were run in three monitor wells. At well 05MW04I, the vertical gradient was upward at depths above 42 feet below land surface (ft bls), downward between 42 and 82 ft bls, and upward below 82 ft bls. At well 05MW05I, a downward vertical gradient was present. At well 05MW12I, the vertical gradient was downward above 112 ft bls and upward below 112 ft bls.Three water-bearing fractures in a 17-foot long rock core from 23.5 to 40.5 ft bls were identified and sampled. Three samples were analyzed from each water-bearing fracture—at the fracture face, 2 centimeters (cm) below the fracture, and 4 cm below the fracture. Fifteen compounds were detected; however, concentrations of seven compounds were less than 1 microgram per kilogram (mg/kg) when detected. Concentrations of benzene (from 0.39 to 3.3 mg/kg), 1,1-dichloroethene (1,1-DCE) (from 0.15 to 13 mg/kg), 1,1,1-trichloroethane (TCA) (from 0.17 to 22 mg/kg), and trichloroethylene (TCE) (from 0.092 to 9.6 mg/kg) were detected in all samples. The highest concentrations detected were for toluene, which was detected at a concentration of 32 and 86 mg/kg in the samples from unweathered sandstone at 2 and 4 cm below the fracture, respectively. Concentrations generally decreased with distance below the fracture in the mudstone samples. Concentrations of benzene and toluene increased with distance below the fractures in the unweathered sandstone samples. Concentrations of 1,1-DCE, TCA, and TCE were higher in the mudstone samples than in the samples from sandstone. Toluene concentrations were higher in unweathered sandstone than in weathered sandstone or mudstone.The effect of the pumping of Horsham Water and Sewer Authority public supply well 26 (HWSA-26), 0.2 mile southwest of the base boundary, on groundwater levels on the base was determined by shutting the well down for 6 days to allow water levels to recover. Water levels in 22 nearby wells were measured. The only well (02MW01I) that showed an unambiguous response to the shutdown of well HWSA-26 is 1,350 feet directly along strike from well HWSA-26. The recovery of well 05MW11I in response to the shutdown of well HWSA-26 is masked by recharge from snowmelt but probably does not exceed about 0.2 feet on the basis of the water level in well 05MW11I, which showed a response to the pumping of well HWSA-26 that ranged from 0.5 to 0.15 foot.Horizontal gradients differ with depth, and the rate and direction of ground-water flow and contaminant movement is depth dependent. The potentiometric-surface map for water levels measured in wells screened between 5 and 44 ft bls in the aquifer shows a ground-water mound that is the high point on a regional ground-water divide. From this divide, ground water flows both northwest toward Park Creek and southeast toward Pennypack Creek. The hydraulic gradient around this mound is relatively flat to the southeast and particularly flat to the northwest. The potentiometric-surface map for water levels measured in wells screened between 40 and 100 ft bls in the aquifer shows a very flat hydraulic gradient. Differences in the elevation of the potentiometric surface are less than 2 feet. The potentiometric-surface map for water levels measured in wells screened between 105 and 179 ft bls in the aquifer shows a steep hydraulic gradient between Sites 5 and 2 and a relatively flat hydraulic gradient between Sites 5 and 3. Water levels measured on October 7, 1999, showed downward vertical head gradients for all well clusters at Site 5. Vertical gradients ranged from 0.01 at well cluster 05MW10 to 0.2 at cluster 05MW11. Most gradients were between 0.01 and 0.026. Vertical head gradients vary with time. The variability is caused by a difference in the magnitude of water-level fluctuations between shallow and the deep fractures. The difference in the magnitude of water-level fluctuations is because of differences in lithology and aquifer storativity.

A Case History of Tracking Water Movement Through Fracture Systems in the Barnett Shale, March 10-11, 2011

EPA Pesticide Factsheets

Technical Presentation Session 6: Monitoring slides to presentation by Denbury on tracking water movement through fracture systems in the Barnett shale. This includes information on micro-seismic well evaluation, well plans, and a fracture map.

NASA Contractor Report: Guidelines for Proof Test Analysis

NASA Technical Reports Server (NTRS)

Chell, G. G.; McClung, R. C.; Kuhlman, C. J.; Russell, D. A.; Garr, K.; Donnelly, B.

1997-01-01

These Guidelines integrate state-of-the-art Elastic-Plastic Fracture Mechanics (EPFM) and proof test implementation issues into a comprehensive proof test analysis procedure in the form of a Road Map which identifies the types of data, fracture mechanics based parameters, and calculations needed to perform flaw screening and minimum proof load analyses of fracture critical components. Worked examples are presented to illustrate the application of the Road Map to proof test analysis. The state-of-the-art fracture technology employed in these Guidelines is based on the EPFM parameter, J, and a pictorial representation of a J fracture analysis, called the Failure Assessment Diagram (FAD) approach. The recommended fracture technology is validated using finite element J results, and laboratory and hardware fracture test results on the nickel-based superalloy IN-718, the aluminum alloy 2024-T351 1, and ferritic pressure vessel steels. In all cases the laboratory specimens and hardware failed by ductile mechanisms. Advanced proof test analyses involving probability analysis and Multiple Cycle Proof Testing (MCPT) are addressed. Finally, recommendations are provided on to how to account for the effects of the proof test overload on subsequent service fatigue and fracture behaviors.

Development of Fracture Mechanics Maps for Composite Materials. Volume 4.

DTIC Science & Technology

1985-12-01

CONSTITUENTS, ETC.) ON NOTCH SENSITIVITY. A LIST OF FRACTURE MODELS AUTHORS REF, ABBRV. CRITERION HOLE SLITS M.E. WADDOUPS J.R. EISENMANN 3 WEK LEFM / / B.E...fracture model) SCF Stress Concentration Factor SIF Stress Intensity Factor WEK Waddoups- Eisenmann -Kaminski (-fracture model) 9 WN Whitney-Nuismer...Technomic Pub. Co., Inc., Stamford, Conn., 1968, pp. 20-43. 3. M.E. Waddoups, J.R. Eisenmann and B.E. Kaminski, "Macroscopic Fracture Mechanics of

Hands-On Exercise in Environmental Structural Geology Using a Fracture Block Model.

ERIC Educational Resources Information Center

Gates, Alexander E.

2001-01-01

Describes the use of a scale analog model of an actual fractured rock reservoir to replace paper copies of fracture maps in the structural geology curriculum. Discusses the merits of the model in enabling students to gain experience performing standard structural analyses. (DDR)

Application of the Risk-Based Early Warning Method in a Fracture-Karst Water Source, North China.

PubMed

Guo, Yongli; Wu, Qing; Li, Changsuo; Zhao, Zhenhua; Sun, Bin; He, Shiyi; Jiang, Guanghui; Zhai, Yuanzheng; Guo, Fang

2018-03-01

  The paper proposes a risk-based early warning considering characteristics of fracture-karst aquifer in North China and applied it in a super-large fracture-karst water source. Groundwater vulnerability, types of land use, water abundance, transmissivity and spatial temporal variation of groundwater quality were chosen as indexes of the method. Weights of factors were obtained by using AHP method based on relative importance of factors, maps of factors were zoned by GIS, early warning map was conducted based on extension theory with the help of GIS, ENVI+IDL. The early warning map fused five factors very well, serious and tremendous warning areas are mainly located in northwest and east with high or relatively high transmissivity and groundwater pollutant loading, and obviously deteriorated or deteriorated trend of petroleum. The early warning map warns people where more attention should be paid, and the paper guides decision making to take appropriate protection actions in different warning levels areas.

Discrete Fracture Network Characterization of Fractured Shale Reservoirs with Implications to Hydraulic Fracturing Optimization

NASA Astrophysics Data System (ADS)

Jin, G.

2016-12-01

Shales are important petroleum source rocks and reservoir seals. Recent developments in hydraulic fracturing technology have facilitated high gas production rates from shale and have had a strong impact on the U.S. gas supply and markets. Modeling of effective permeability for fractured shale reservoirs has been challenging because the presence of a fracture network significantly alters the reservoir hydrologic properties. Due to the frequent occurrence of fracture networks, it is of vital importance to characterize fracture networks and to investigate how these networks can be used to optimize the hydraulic fracturing. We have conducted basic research on 3-D fracture permeability characterization and compartmentization analyses for fractured shale formations, which takes the advantages of the discrete fracture networks (DFN). The DFN modeling is a stochastic modeling approach using the probabilistic density functions of fractures. Three common scenarios of DFN models have been studied for fracture permeability mapping using our previously proposed techniques. In DFN models with moderately to highly concentrated fractures, there exists a representative element volume (REV) for fracture permeability characterization, which indicates that the fractured reservoirs can be treated as anisotropic homogeneous media. Hydraulic fracturing will be most effective if the orientation of the hydraulic fracture is perpendicular to the mean direction of the fractures. A DFN model with randomized fracture orientations, on the other hand, lacks an REV for fracture characterization. Therefore, a fracture permeability tensor has to be computed from each element. Modeling of fracture interconnectivity indicates that there exists no preferred direction for hydraulic fracturing to be most effective oweing to the interconnected pathways of the fracture network. 3-D fracture permeability mapping has been applied to the Devonian Chattanooga Shale in Alabama and the results suggest that an REV exist for fluid flow and transport modeling at element sizes larger than 200 m. Fracture pathway analysis indicates that hydraulic fracturing can be equally effective for hydrocarbon fluid/gas exploration as long as its orientation is not aligned with that of the regional system fractures.

Compressive Stress-Induced Microcracks and Effective Elastic Properties of Limestone and Concrete. Phase 1

DTIC Science & Technology

1991-04-19

McLennan (Technical Consultant) Ph.D. Rock Mechanics, University of Toronto, 1980. Thesis Title: " Hydraulic Fracturing : A Fracture Mechanics Approach...the principal stresses. Certain techniques such as micro- hydraulic fracturing , televiewer surveys and mapping of borehole breakouts have been used to

Outcrop-scale fracture trace identification using surface roughness derived from a high-density point cloud

NASA Astrophysics Data System (ADS)

Okyay, U.; Glennie, C. L.; Khan, S.

2017-12-01

Owing to the advent of terrestrial laser scanners (TLS), high-density point cloud data has become increasingly available to the geoscience research community. Research groups have started producing their own point clouds for various applications, gradually shifting their emphasis from obtaining the data towards extracting more and meaningful information from the point clouds. Extracting fracture properties from three-dimensional data in a (semi-)automated manner has been an active area of research in geosciences. Several studies have developed various processing algorithms for extracting only planar surfaces. In comparison, (semi-)automated identification of fracture traces at the outcrop scale, which could be used for mapping fracture distribution have not been investigated frequently. Understanding the spatial distribution and configuration of natural fractures is of particular importance, as they directly influence fluid-flow through the host rock. Surface roughness, typically defined as the deviation of a natural surface from a reference datum, has become an important metric in geoscience research, especially with the increasing density and accuracy of point clouds. In the study presented herein, a surface roughness model was employed to identify fracture traces and their distribution on an ophiolite outcrop in Oman. Surface roughness calculations were performed using orthogonal distance regression over various grid intervals. The results demonstrated that surface roughness could identify outcrop-scale fracture traces from which fracture distribution and density maps can be generated. However, considering outcrop conditions and properties and the purpose of the application, the definition of an adequate grid interval for surface roughness model and selection of threshold values for distribution maps are not straightforward and require user intervention and interpretation.

A web-based multicriteria evaluation of spatial trade-offs between environmental and economic implications from hydraulic fracturing in a shale gas region in Ohio.

PubMed

Liu, X; Gorsevski, P V; Yacobucci, M M; Onasch, C M

2016-06-01

Planning of shale gas infrastructure and drilling sites for hydraulic fracturing has important spatial implications. The evaluation of conflicting and competing objectives requires an explicit consideration of multiple criteria as they have important environmental and economic implications. This study presents a web-based multicriteria spatial decision support system (SDSS) prototype with a flexible and user-friendly interface that could provide educational or decision-making capabilities with respect to hydraulic fracturing site selection in eastern Ohio. One of the main features of this SDSS is to emphasize potential trade-offs between important factors of environmental and economic ramifications from hydraulic fracturing activities using a weighted linear combination (WLC) method. In the prototype, the GIS-enabled analytical components allow spontaneous visualization of available alternatives on maps which provide value-added features for decision support processes and derivation of final decision maps. The SDSS prototype also facilitates nonexpert participation capabilities using a mapping module, decision-making tool, group decision module, and social media sharing tools. The logical flow of successively presented forms and standardized criteria maps is used to generate visualization of trade-off scenarios and alternative solutions tailored to individual user's preferences that are graphed for subsequent decision-making.

A new approach to fracture modelling in reservoirs using deterministic, genetic and statistical models of fracture growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rawnsley, K.; Swaby, P.

1996-08-01

It is increasingly acknowledged that in order to understand and forecast the behavior of fracture influenced reservoirs we must attempt to reproduce the fracture system geometry and use this as a basis for fluid flow calculation. This article aims to present a recently developed fracture modelling prototype designed specifically for use in hydrocarbon reservoir environments. The prototype {open_quotes}FRAME{close_quotes} (FRActure Modelling Environment) aims to provide a tool which will allow the generation of realistic 3D fracture systems within a reservoir model, constrained to the known geology of the reservoir by both mechanical and statistical considerations, and which can be used asmore » a basis for fluid flow calculation. Two newly developed modelling techniques are used. The first is an interactive tool which allows complex fault surfaces and their associated deformations to be reproduced. The second is a {open_quotes}genetic{close_quotes} model which grows fracture patterns from seeds using conceptual models of fracture development. The user defines the mechanical input and can retrieve all the statistics of the growing fractures to allow comparison to assumed statistical distributions for the reservoir fractures. Input parameters include growth rate, fracture interaction characteristics, orientation maps and density maps. More traditional statistical stochastic fracture models are also incorporated. FRAME is designed to allow the geologist to input hard or soft data including seismically defined surfaces, well fractures, outcrop models, analogue or numerical mechanical models or geological {open_quotes}feeling{close_quotes}. The geologist is not restricted to {open_quotes}a priori{close_quotes} models of fracture patterns that may not correspond to the data.« less

An Application of Hydraulic Tomography to a Large-Scale Fractured Granite Site, Mizunami, Japan.

PubMed

Zha, Yuanyuan; Yeh, Tian-Chyi J; Illman, Walter A; Tanaka, Tatsuya; Bruines, Patrick; Onoe, Hironori; Saegusa, Hiromitsu; Mao, Deqiang; Takeuchi, Shinji; Wen, Jet-Chau

2016-11-01

While hydraulic tomography (HT) is a mature aquifer characterization technology, its applications to characterize hydrogeology of kilometer-scale fault and fracture zones are rare. This paper sequentially analyzes datasets from two new pumping tests as well as those from two previous pumping tests analyzed by Illman et al. (2009) at a fractured granite site in Mizunami, Japan. Results of this analysis show that datasets from two previous pumping tests at one side of a fault zone as used in the previous study led to inaccurate mapping of fracture and fault zones. Inclusion of the datasets from the two new pumping tests (one of which was conducted on the other side of the fault) yields locations of the fault zone consistent with those based on geological mapping. The new datasets also produce a detailed image of the irregular fault zone, which is not available from geological investigation alone and the previous study. As a result, we conclude that if prior knowledge about geological structures at a field site is considered during the design of HT surveys, valuable non-redundant datasets about the fracture and fault zones can be collected. Only with these non-redundant data sets, can HT then be a viable and robust tool for delineating fracture and fault distributions over kilometer scales, even when only a limited number of boreholes are available. In essence, this paper proves that HT is a new tool for geologists, geophysicists, and engineers for mapping large-scale fracture and fault zone distributions. © 2016, National Ground Water Association.

Full waveform approach for the automatic detection and location of acoustic emissions from hydraulic fracturing at Äspö (Sweden)

NASA Astrophysics Data System (ADS)

Ángel López Comino, José; Cesca, Simone; Heimann, Sebastian; Grigoli, Francesco; Milkereit, Claus; Dahm, Torsten; Zang, Arno

2017-04-01

A crucial issue to analyse the induced seismicity for hydraulic fracturing is the detection and location of massive microseismic or acoustic emissions (AE) activity, with robust and sufficiently accurate automatic algorithms. Waveform stacking and coherence analysis have been tested for local seismic monitoring and mining induced seismicity improving the classical detection and location methods (e.g. short-term-average/long-term-average and automatic picking of the P and S waves first arrivals). These techniques are here applied using a full waveform approach for a hydraulic fracturing experiment (Nova project 54-14-1) that took place 410 m below surface in the Äspö Hard Rock Laboratory (Sweden). Continuous waveform recording with a near field network composed by eleven AE sensors are processed. The piezoelectric sensors have their highest sensitive in the frequency range 1 to 100 kHz, but sampling rates were extended to 1 MHz. We present the results obtained during the conventional, continuous water-injection experiment HF2 (Hydraulic Fracture 2). The event detector is based on the stacking of characteristic functions. It follows a delay-and-stack approach, where the likelihood of the hypocenter location in a pre-selected seismogenic volume is mapped by assessing the coherence of the P onset times at different stations. A low detector threshold is chosen, in order not to loose weaker events. This approach also increases the number of false detections. Therefore, the dataset has been revised manually, and detected events classified in terms of true AE events related to the fracturing process, electronic noise related to 50 Hz overtones, long period and other signals. The location of the AE events is further refined using a more accurate waveform stacking method which uses both P and S phases. A 3D grid is generated around the hydraulic fracturing volume and we retrieve a multidimensional matrix, whose absolute maximum corresponds to the spatial coordinates of the seismic event. The relative location accuracy is improved using a master event approach to correct for travel time perturbations. The master event is selected based on a good signal to noise ratio leading to a robust location with small uncertainties. Relative magnitudes are finally estimated upon the decay of the maximal recorded amplitude from the AE location. The resulting catalogue is composed of more than 4000 AEs. Their hypocenters are spatially clustered in a planar region, resembling the main fracture plane; its orientation and size are estimated from the spatial distribution of AEs. This work is funded by the EU H2020 SHEER project. Nova project 54-14-1 was financially supported by the GFZ German Research Center for Geosciences (75%), the KIT Karlsruhe Institute of Technology (15%) and the Nova Center for University Studies, Research and Development (10%). An additional in-kind contribution of SKB for using Äspö Hard Rock Laboratory as test site for geothermal research is greatly acknowledged.

Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico)

NASA Astrophysics Data System (ADS)

Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.

2013-12-01

This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

Fracture network topology and characterization of structural permeability

NASA Astrophysics Data System (ADS)

Hansberry, Rowan; King, Rosalind; Holford, Simon

2017-04-01

There are two fundamental requirements for successful geothermal development: elevated temperatures at accessible depths, and a reservoir from which fluids can be extracted. The Australian geothermal sector has successfully targeted shallow heat, however, due in part to the inherent complexity of targeting permeability, obtaining adequate flow rates for commercial production has been problematic. Deep sedimentary aquifers are unlikely to be viable geothermal resources due to the effects of diagenetic mineral growth on rock permeability. Therefore, it is likely structural permeability targets, exploiting natural or induced fracture networks will provide the primary means for fluid flow in geothermal, as well as unconventional gas, reservoirs. Recent research has focused on the pattern and generation of crustal stresses across Australia, while less is known about the resultant networks of faults, joints, and veins that can constitute interconnected sub-surface permeability pathways. The ability of a fracture to transmit fluid is controlled by the orientation and magnitude of the in-situ stress field that acts on the fracture walls, rock strength, and pore pressure, as well as fracture properties such as aperture, orientation, and roughness. Understanding the distribution, orientation and character of fractures is key to predicting structural permeability. This project focuses on extensive mapping of fractures over various scales in four key Australian basins (Cooper, Otway, Surat and Perth) with the potential to host geothermal resources. Seismic attribute analysis is used in concert with image logs from petroleum wells, and field mapping to identify fracture networks that are usually not resolved in traditional seismic interpretation. We use fracture network topology to provide scale-invariant characterisation of fracture networks from multiple data sources to assess similarity between data sources, and fracture network connectivity. These results are compared with other permeability indicators such as drilling fluid losses, and pore pressure measurements. Initial work with these techniques has led to new developments in our ability to image subsurface faults and fractures at a variety of scales from independent datasets. We establish a strong relationship between features identified using seismic attribute analysis and interpreted natural fractures. However, care must be taken to use these methods in a case-by-case basis, as controls on fracture distribution and orientation can vary significantly with both regional and local influences. These results outline and effective method by which structural permeability can be assessed with existing petroleum datasets. However, unlike the broad stress field, mapping fracture orientation and characteristics within the Australian Continent is complicated as the distribution, geometry, areal extent and connectivity of fracture networks can vary significantly.

The seismogenic Gole Larghe Fault Zone (Italian Southern Alps): quantitative 3D characterization of the fault/fracture network, mapping of evidences of fluid-rock interaction, and modelling of the hydraulic structure through the seismic cycle

NASA Astrophysics Data System (ADS)

Bistacchi, A.; Mittempergher, S.; Di Toro, G.; Smith, S. A. F.; Garofalo, P. S.

2016-12-01

The Gole Larghe Fault Zone (GLFZ) was exhumed from 8 km depth, where it was characterized by seismic activity (pseudotachylytes) and hydrous fluid flow (alteration halos and precipitation of hydrothermal minerals in veins and cataclasites). Thanks to glacier-polished outcrops exposing the 400 m-thick fault zone over a continuous area > 1.5 km2, the fault zone architecture has been quantitatively described with an unprecedented detail, providing a rich dataset to generate 3D Discrete Fracture Network (DFN) models and simulate the fault zone hydraulic properties. The fault and fracture network has been characterized combining > 2 km of scanlines and semi-automatic mapping of faults and fractures on several photogrammetric 3D Digital Outcrop Models (3D DOMs). This allowed obtaining robust probability density functions for parameters of fault and fracture sets: orientation, fracture intensity and density, spacing, persistency, length, thickness/aperture, termination. The spatial distribution of fractures (random, clustered, anticlustered…) has been characterized with geostatistics. Evidences of fluid/rock interaction (alteration halos, hydrothermal veins, etc.) have been mapped on the same outcrops, revealing sectors of the fault zone strongly impacted, vs. completely unaffected, by fluid/rock interaction, separated by convolute infiltration fronts. Field and microstructural evidence revealed that higher permeability was obtained in the syn- to early post-seismic period, when fractures were (re)opened by off-fault deformation. We have developed a parametric hydraulic model of the GLFZ and calibrated it, varying the fraction of faults/fractures that were open in the post-seismic, with the goal of obtaining realistic fluid flow and permeability values, and a flow pattern consistent with the observed alteration/mineralization pattern. The fraction of open fractures is very close to the percolation threshold of the DFN, and the permeability tensor is strongly anisotropic, resulting in a marked channelling of fluid flow in the inner part of the fault zone. Amongst possible seismological applications of our study, we will discuss the possibility to evaluate the coseismic fracture intensity due to off-fault damage, a fundamental mechanical parameter in the energy balance of earthquakes.

Remote Sensing Applications for Antrim Shale Fracture Characterization, Michigan Basin

NASA Technical Reports Server (NTRS)

Kuuskraa, Vello

1997-01-01

Advanced Research International (ARI) sent seven staff members to the 1997 International Coalbed Methane Symposium, held in Tuscaloosa, Alabama from May 12-17. ARI gave a short course on risk reduction strategies, including remote fracture detection, for coalbed methane exploration and development that was attended by about 25 coalbed methane industry professionals; and presented a paper entitled 'Optimizing coalbed methane cavity completion operations with the application of a new discrete element model.' We met with many potential clients and discussed our fracture detection services. China has vast coalbed methane resources, but is still highly dependent on coal-and wood-burning. This workshop, sponsored by the United Nations, was intended to help China develop its less-polluting energy reserves. ARI is successfully finding new applications for its fracture detection services. Coalbed methane exploration became an important market in this quarter, with the inception of a joint industry/government collaboration between ARI, Texaco and DOE to use remote fracture detection to identify areas with good potential for coalbed methane production in the Ferron Coal Trend of central Utah. Geothermal energy exploration is another emerging market for ARI, where fracture detection is applied to identify pathways for groundwater recharge, movement, and the locations of potential geothermal reservoirs. Ari continued work on two industry/government collaborations to demonstrate fracture detection to potential clients. Also completed the technical content layout for multimedia CD-ROM that describes our remote fracture detection services.

Orientation-dependent tensile deformation and damage of a T700 carbon fiber/epoxy composite: A synchrotron-based study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bie, B. X.; Huang, J. Y.; Fan, D.

Uniaxial tensile experiments are conducted on a T700 carbon fiber/epoxy composite along various offaxis angles. Stressestrain curves are measured along with strain fields mapped via synchrotron x-ray digital image correlation, as well as computerized tomography. Elastic modulus and tensile strength decrease with increasing off-axis angles, while fracture strain exhibits a nonmonotonic trend as a combined result of tensile strength decrease and fracture mode transition. At high off-axis angles, strain field mapping demonstrates distinct tensile and shear strain localizations and deformation bands approximately along the fiber directions, while deformation is mainly achieved via continuous growth of tensile strain at low off-axismore » angles. Roughness of fracture planes decreases exponentially as the off-axis angle increases. The stressestrain curves, strain fields, tomography and fractographs show consistent features, and reveal a fracture mode transition from mainly tension (fiber fracture) to in-plane shear (interface debonding).« less

Sex-Specific Genetic Loci for Femoral Neck Bone Mass and Strength Identified in Inbred COP and DA Rats

PubMed Central

Alam, Imranul; Sun, Qiwei; Liu, Lixiang; Koller, Daniel L; Carr, Lucinda G; Econs, Michael J; Foroud, Tatiana; Turner, Charles H

2008-01-01

Introduction Hip fracture is the most devastating osteoporotic fracture type with significant morbidity and mortality. Several studies in humans identified chromosomal regions linked to hip size and bone mass. Animal models, particularly the inbred rat, serve as complementary approaches for studying the genetic influence on hip fragility. The purpose of this study is to identify sex-independent and sex-specific quantitative trait loci (QTLs) for femoral neck density, structure, and strength in inbred Copenhagen 2331 (COP) and Dark Agouti (DA) rats. Materials and Methods A total of 828 (405 males and 423 females) F2 progeny derived from the inbred COP and DA strains of rats were phenotyped for femoral neck volumetric BMD (vBMD), cross-sectional area, polar moment of inertia (Ip), neck width, ultimate force, and energy to break. A whole genome screen was performed using 93 microsatellite markers with an average intermarker distance of 20 cM. Recombination-based marker maps were generated using MAPMAKER/EXP from the COP × DA F2 data and compared with published Rat Genome Database (RGD) maps. These maps were used for genome-wide linkage analyses to detect sex-independent and sex-specific QTLs. Results Significant evidence of linkage (p < 0.01) for sex-independent QTLs were detected for (1) femoral neck vBMD on chromosomes (Chrs) 1, 6, 10, and 12, (2) femoral neck structure on Chrs 5, 7, 10, and 18, and (3) biomechanical properties on Chrs 1 and 4. Male-specific QTLs were discovered on Chrs 2, 9, and 18 for total vBMD, on Chr 17 for trabecular vBMD, on Chr 9 for total bone area, and on Chr 15 for ultimate force. A female-specific QTL was discovered on Chr 2 for ultimate force. The effect size of the individual QTL varied between 1% and 4%. Conclusions We detected evidence that sex-independent and sex-specific QTLs contribute to hip fragility in the inbred rat. Several QTLs regions identified in this study are homologous to human chromosomal regions previously linked to QTLs contributing to femoral neck and related phenotypes. PMID:18282130

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parra, J.; Collier, H.; Angstman, B.

In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based upon the effects of such conditions on the propagation of acoustic and seismic waves in the rock. We present the feasibility of using seismic measurement techniques to map the fracture zones between wells spaced 2400 ft at depths of about 1000 ft.more » For this purpose we constructed computer models (which include azimuthal anisotropy) using Lodgepole reservoir parameters to predict seismic signatures recorded at the borehole scale, crosswell scale, and 3 D seismic scale. We have integrated well logs with existing 2D surfaces seismic to produce petrophysical and geological cross sections to determine the reservoir parameters and geometry for the computer models. In particular, the model responses are used to evaluate if surface seismic and crosswell seismic measurements can capture the anisotropy due to vertical fractures. Preliminary results suggested that seismic waves transmitted between two wells will propagate in carbonate fracture reservoirs, and the signal can be received above the noise level at the distance of 2400 ft. In addition, the large velocities contrast between the main fracture zone and the underlying unfractured Boundary Ridge Member, suggested that borehole reflection imaging may be appropriate to map and fracture zone thickness variation and fracture distributions in the reservoir.« less

Controlled Source Electromagnetic Monitoring of Hydraulic Fracturing: Wellbore and Fluid Effects

NASA Astrophysics Data System (ADS)

Couchman, M. J.; Everett, M. E.

2017-12-01

As unconventional resources become increasingly important, we must tackle the issue of real-time monitoring of the efficiency of unconventional hydrocarbon extraction. Controlled Source Electromagnetics (CSEM) have been used primarily as a marine-based technique to monitor conventional oil bearing reservoirs with a strong resurgence the new millennium. Many of these studies revolving around detecting a thin resistive layer such as a reservoir at 1m - 3km depth. In these cases, the presence of the resistive layer is characterized by a jump in electric field amplitude recorded at the boundary between the layer and the host sediments. The lessons learned from these studies can be applied to terrestrial unconventional settings with appropriate modifications. The work shown here is a means develop methods which enable more reliable terrestrial CSEM monitoring of the flow of injected fluids associated with hydraulic fracturing of unconventional reservoirs and to detect subsurface fluids based on their CSEM signature and in turn, to infer the subsurface flow of electrically conductive injected fluids. The predictive model validated for various 1-D marine, and terrestrial cases focus on the mapping of fluid flow in from a horizontal wellbore in a uniform halfspace using an in-line Horizontal Electric Dipole (HED) with electric field amplitude recorded by an array of electric field sensors. The effect of the of the vertical and horizontal wellbores are documented taking into account the conductivity, size, and thickness of each wellbore. The fracturing fluids flow and conductivity are also taken into account throughout various stages of the fracturing process. In each case, the sensitivity at a location of the surface in-line electric field to a given resistive or conductive layer, due to a source is calculated.

Electromagnetic Monitoring of Hydraulic Fracturing: Relationship to Permeability, Seismicity, and Stress

NASA Astrophysics Data System (ADS)

Thiel, Stephan

2017-09-01

Hydraulic fracking is a geoengineering application designed to enhance subsurface permeability to maximize fluid and gas flow. Fracking is commonly used in enhanced geothermal systems (EGS), tight shale gas, and coal seam gas (CSG) plays and in CO_2 storage scenarios. Common monitoring methods include microseismics and mapping small earthquakes with great resolution associated with fracture opening at reservoir depth. Recently, electromagnetic (EM) methods have been employed in the field to provide an alternative way of direct detection of fluids as they are pumped in the ground. Surface magnetotelluric (MT) measurements across EGS show subtle yet detectable changes during fracking derived from time-lapse MT deployments. Changes are directional and are predominantly aligned with current stress field, dictating preferential fracture orientation, supported by microseismic monitoring of frack-related earthquakes. Modeling studies prior to the injection are crucial for survey design and feasibility of monitoring fracks. In particular, knowledge of sediment thickness plays a fundamental role in resolving subtle changes. Numerical forward modeling studies clearly favor some form of downhole measurement to enhance sensitivity; however, these have yet to be conclusively demonstrated in the field. Nevertheless, real surface-based monitoring examples do not necessarily replicate the expected magnitude of change derived from forward modeling and are larger than expected in some cases from EGS and CSG systems. It appears the injected fluid volume alone cannot account for the surface change in resistivity, but connectedness of pore space is also significantly enhanced and nonlinear. Recent numerical studies emphasize the importance of percolation threshold of the fracture network on both electrical resistivity and permeability, which may play an important role in accounting for temporal changes in surface EM measurements during hydraulic fracking.

"Buckle" rib fracture: an artifact following cardio-pulmonary resuscitation detected on postmortem CT.

PubMed

Yang, Kyung-Moo; Lynch, Matthew; O'Donnell, Chris

2011-09-01

Buckle rib fractures are incomplete fractures involving the inner cortex alone, and are rarely detected on routine chest X-ray or at autopsy. The characteristics of these fractures have not been well evaluated in situ although they are commonly observed on postmortem CT images especially following CPR. The postmortem CT findings in 42 cases showing buckle rib fractures caused by CPR were reviewed. The cause of death in all cases was non-traumatic. The shape, number, location, and distribution of these buckle rib fractures and their relationship to other types of rib fractures were evaluated using a novel oblique axial multiplanar reconstruction technique. Almost all incomplete rib fractures associated with CPR are buckle rib fractures (90.5%). All rib fractures were distributed from the second to ninth ribs with over 95% being within the second to seventh ribs. Buckle rib fractures are dominant in the seventh to ninth ribs and the proportion of buckle rib fractures located in the vicinity of the costochondral junctions increases with the lower ribs. Over 97% of all CPR associated rib fractures are located in the anterior one third of the ribs based on a new measurement method utilizing oblique axial multiplanar reconstruction of the CT data. When recognition of incomplete or buckle rib fractures on postmortem CT is taken into account, detection of symmetry and continuity of rib fractures typically associated with CPR is improved compared with the detection of complete fractures alone. Recognition of buckle rib fractures and their characteristics on postmortem CT is of benefit to the forensic pathologist in evaluating the possibility of CPR and the differentiation of resuscitative artifact from forensically significant visceral injury observed at autopsy. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Evaluation of Hydraulically Significant Discontinuities in Dockum Group Mudrocks in Andrews County, Texas

NASA Astrophysics Data System (ADS)

Holt, R. M.; Kuszmaul, J. S.; Cao, S.; Powers, D. W.

2013-12-01

Triassic mudrocks of the Dockum Group (Cooper Canyon Formation) host four, below-grade landfills at the Waste Control Specialists (WSC) site in Andrews County, Texas, including: a hazardous waste landfill and three radioactive waste landfills. At the study site, the Dockum consists of mudrocks with sparse siltstone/sandstone interbeds that developed in a semi-arid environment from an ephemeral meandering fluvial system. Sedimentary studies reveal that the mudrocks are ancient floodplain vertisols (soils with swelling clays) and siltstone/sandstone interbeds are fluvial channel deposits that were frequently subaerially exposed. Rock discontinuities, including fractures and syndepositional slickensided surfaces, were mapped during the excavation of the WCS radioactive waste landfills along vertical faces prepared by the construction contractor. Face locations were selected to insure a sampled area with nearly complete vertical coverage for each landfill. Individual discontinuities were mapped and their strike, dip, length, roughness, curvature, staining, and evidence of displacement were described. In the three radioactive waste disposal landfills, over 1750 discontinuities across 35 excavated faces were mapped and described, where each face was nominally 8 to 10 ft tall and 50 to 100 ft long. Genetic units related to paleosol development were identified. On average, the orientation of the discontinuities was horizontal, and no other significant trends were observed. Mapping within the landfill excavations shows that most discontinuities within Dockum rocks are horizontal, concave upward, slickensided surfaces that developed in the depositional environment, as repeated wetting and drying cycles led to shrinking and swelling of floodplain vertisols. Fractures that showed staining (a possible indicator of past or present hydraulic activity) are rare, vertical to near-vertical, and occur mainly in, and adjacent to, mechanically stiff siltstone and sandstone interbeds. No interconnected fracture networks were observed during mapping. A series of pressurized air tests conducted in three pairs of vertical and three pairs of inclined boreholes were tested at depths, ranging from 40 to 215 feet below ground surface, also showed no evidence of fracture interconnection. Genetic units generally consist of fining upward sequences that show increasing pedogenic alteration upward. Arcuate, slickensided discontinuities are more abundant near the top of genetic units, while stained fractures are more common in the more mechanically competent materials near the base of genetic units. A statistical analysis of fractures and discontinuities revealed limited differences between most genetic units. A series of discrete fracture network models were developed to evaluate the uncertainty in our fracture observations. Slickensided discontinuities showing no evidence of staining or past fluid movement were excluded from the analysis. Monte Carlo simulations show no continuous fracture interconnections across the landfill depth intervals.

Radon Outgassing in the Casa Diablo Region, Long Valley Caldera, California

NASA Astrophysics Data System (ADS)

Adarkwah, N.; Cuff, K.

2003-12-01

A radon outgassing survey has been conducted in the Casa Diablo region of the Long Valley Caldera. The Long Valley Caldera (LVC) is an active volcanic system situated along the eastern front of the Sierra Nevada mountain range in east-central California. The survey was centered in an area .4 km northwest of the Casa Diablo geothermal power plant, located along the southwestern-most rim of the caldera?s resurgent dome. Results from previous radon emission studies in LVC indicate that high degrees of outgassing occur in association with relatively narrow networks of unsealed fractures (Cuff, et al., 2000 and Hoyos, et al., 2001). These fracture networks act as pathways for radon and other gases generated at depth as they migrate toward the surface. The purpose of the present study was to determine whether or not a relationship exists between radon emissions in the current survey area and that in a previously surveyed area approximately .8 km west of the geothermal plant. To accomplish this, we measured radon concentration in soil-gas at 35 separate sites. These sites were located within a 140 by 100 meter grid, with 20 meter spacing between each sample site. A radon outgassing map was then created using measured concentration values along with longitude and latitude values for each sample location. Geologic maps of the area were also analyzed and compared with radon outgassing maps. Analysis of these maps indicates that radon outgassing occurs through a set of crisscrossing fractures, trending southwest-northeast and northwest-southeast respectively. The northwest trending fractures are related to mapped normal faults in the area, while those with a southwest-northeast orientation are associated with an unmapped zone of faulting that is roughly perpendicular to the other faults. The latter set of fractures has a trend similar to that discovered in the previously surveyed area to the west. In both areas the highest readings were in excess of three times background radon concentration values measured in the field, and were obtained at locations believed to be where two sets of fractures intersect.

Challenges of using electrical resistivity method to locate karst conduits-A field case in the Inner Bluegrass Region, Kentucky

USGS Publications Warehouse

Zhu, J.; Currens, J.C.; Dinger, J.S.

2011-01-01

Conduits serve as major pathways for groundwater flow in karst aquifers. Locating them from the surface, however, is one of the most challenging tasks in karst research. Geophysical methods are often deployed to help locate voids by mapping variations of physical properties of the subsurface. Conduits can cause significant contrasts of some physical properties that can be detected; other subsurface features such as water-bearing fractures often yield similar contrasts, which are difficult to distinguish from the effects of the conduits. This study used electrical resistivity method to search for an unmapped karst conduit that recharges Royal Spring in the Inner Bluegrass karst region, Kentucky, USA. Three types of resistivity techniques (surface 2D survey, quasi-3D survey, and time-lapse survey) were used to map and characterize resistivity anomalies. Some of the major anomalies were selected as drilling targets to verify the existence of the conduits. Drilling near an anomaly identified by an electrical resistivity profile resulted in successful penetration of a major water-filled conduit. The drilling results also suggest that, in this study area, low resistivity anomalies in general are associated with water-bearing features. However, differences in the anomaly signals between the water-filled conduit and other water-bearing features such as water-filled fracture zones were undistinguishable. The electrical resistivity method is useful in conduit detection by providing potential drilling targets. Knowledge of geology and hydrogeology about the site and professional judgment also played important roles in locating the major conduit. ?? 2011 Elsevier B.V.

Ability of Ultrasonography in Detection of Different Extremity Bone Fractures; a Case Series Study

PubMed Central

Bozorgi, Farzad; Shayesteh Azar, Massoud; Montazer, Seyed Hossein; Chabra, Aroona; Heidari, Seyed Farshad; Khalilian, Alireza

2017-01-01

Introduction: Despite radiography being the gold standard in evaluation of orthopedic injuries, using bedside ultrasonography has several potential supremacies such as avoiding exposure to ionizing radiation, availability in pre-hospital settings, being extensively accessible, and ability to be used on the bedside. The aim of the present study is to evaluate the diagnostic accuracy of ultrasonography in detection of extremity bone fractures. Methods: This study is a case series study, which was prospectively conducted on multiple blunt trauma patients, who were 18 years old or older, had stable hemodynamic, Glasgow coma scale 15, and signs or symptoms of a possible extremity bone fracture. After initial assessment, ultrasonography of suspected bones was performed by a trained emergency medicine resident and prevalence of true positive and false negative findings were calculated compared to plain radiology. Results: 108 patients with the mean age of 44.6 ± 20.4 years were studied (67.6% male). Analysis was done on 158 sites of fracture, which were confirmed with plain radiography. 91 (57.6%) cases were suspected to have upper extremity fracture(s) and 67 (42.4%) to have lower ones. The most frequent site of injuries were forearm (36.7%) in upper limbs and leg (27.8%) in lower limbs. Prevalence of true positive and false negative cases for fractures detected by ultrasonography were 59 (64.8%) and 32 (35.52%) for upper and 49 (73.1%) and 18 (26.9%) for lower extremities, respectively. In addition, prevalence of true positive and false negative detected cases for intra-articular fractures were 24 (48%) and 26 (52%), respectively. Conclusion The present study shows the moderate sensitivity (68.3%) of ultrasonography in detection of different extremity bone fractures. Ultrasonography showed the best sensitivity in detection of femur (100%) and humerus (76.2%) fractures, respectively. It had low sensitivity in detection of in intra-articular fractures. PMID:28286822

Ability of Ultrasonography in Detection of Different Extremity Bone Fractures; a Case Series Study.

PubMed

Bozorgi, Farzad; Shayesteh Azar, Massoud; Montazer, Seyed Hossein; Chabra, Aroona; Heidari, Seyed Farshad; Khalilian, Alireza

2017-01-01

Despite radiography being the gold standard in evaluation of orthopedic injuries, using bedside ultrasonography has several potential supremacies such as avoiding exposure to ionizing radiation, availability in pre-hospital settings, being extensively accessible, and ability to be used on the bedside. The aim of the present study is to evaluate the diagnostic accuracy of ultrasonography in detection of extremity bone fractures. This study is a case series study, which was prospectively conducted on multiple blunt trauma patients, who were 18 years old or older, had stable hemodynamic, Glasgow coma scale 15, and signs or symptoms of a possible extremity bone fracture. After initial assessment, ultrasonography of suspected bones was performed by a trained emergency medicine resident and prevalence of true positive and false negative findings were calculated compared to plain radiology. 108 patients with the mean age of 44.6 ± 20.4 years were studied (67.6% male). Analysis was done on 158 sites of fracture, which were confirmed with plain radiography. 91 (57.6%) cases were suspected to have upper extremity fracture(s) and 67 (42.4%) to have lower ones. The most frequent site of injuries were forearm (36.7%) in upper limbs and leg (27.8%) in lower limbs. Prevalence of true positive and false negative cases for fractures detected by ultrasonography were 59 (64.8%) and 32 (35.52%) for upper and 49 (73.1%) and 18 (26.9%) for lower extremities, respectively. In addition, prevalence of true positive and false negative detected cases for intra-articular fractures were 24 (48%) and 26 (52%), respectively. The present study shows the moderate sensitivity (68.3%) of ultrasonography in detection of different extremity bone fractures. Ultrasonography showed the best sensitivity in detection of femur (100%) and humerus (76.2%) fractures, respectively. It had low sensitivity in detection of in intra-articular fractures.

Percolation of fracture networks and stereology

NASA Astrophysics Data System (ADS)

Thovert, Jean-Francois; Mourzenko, Valeri; Adler, Pierre

2017-04-01

The overall properties of fractured porous media depend on the percolative character of the fracture network in a crucial way. The most important examples are permeability and transport. In a recent systematic study, a very wide range of regular, irregular and random fracture shapes is considered, in monodisperse or polydisperse networks containing fractures with different shapes and/or sizes. A simple and new model involving a dimensionless density and a new shape factor is proposed for the percolation threshold, which accounts very efficiently for the influence of the fracture shape. It applies with very good accuracy to monodisperse or moderately polydisperse networks, and provides a good first estimation in other situations. A polydispersity index is shown to control the need for a correction, and the corrective term is modelled for the investigated size distributions. Moreover, and this is crucial for practical applications, the relevant quantities which are present in the expression of the percolation threshold can all be determined from trace maps. An exact and complete set of relations can be derived when the fractures are assumed to be Identical, Isotropically Oriented and Uniformly Distributed (I2OUD). Therefore, the dimensionless density of such networks can be derived directly from the trace maps and its percolating character can be a priori predicted. These relations involve the first five moments of the trace lengths. It is clear that the higher order moments are sensitive to truncation due to the boundaries of the sampling domain. However, it can be shown that the truncation effect can be fully taken into account and corrected, for any fracture shape, size and orientation distributions, if the fractures are spatially uniformly distributed. Systematic applications of these results are made to real fracture networks that we previously analyzed by other means and to numerically simulated networks. It is important to know if the stereological results and their applications can be extended to networks which are not I2OUD. In other words, for a given trace map, an equivalent I2OUD network is defined whose percolating character and permeability are readily deduced. The conditions under which these predicted properties are not too far from the real properties are under investigation.

Lining seam elimination algorithm and surface crack detection in concrete tunnel lining

NASA Astrophysics Data System (ADS)

Qu, Zhong; Bai, Ling; An, Shi-Quan; Ju, Fang-Rong; Liu, Ling

2016-11-01

Due to the particularity of the surface of concrete tunnel lining and the diversity of detection environments such as uneven illumination, smudges, localized rock falls, water leakage, and the inherent seams of the lining structure, existing crack detection algorithms cannot detect real cracks accurately. This paper proposed an algorithm that combines lining seam elimination with the improved percolation detection algorithm based on grid cell analysis for surface crack detection in concrete tunnel lining. First, check the characteristics of pixels within the overlapping grid to remove the background noise and generate the percolation seed map (PSM). Second, cracks are detected based on the PSM by the accelerated percolation algorithm so that the fracture unit areas can be scanned and connected. Finally, the real surface cracks in concrete tunnel lining can be obtained by removing the lining seam and performing percolation denoising. Experimental results show that the proposed algorithm can accurately, quickly, and effectively detect the real surface cracks. Furthermore, it can fill the gap in the existing concrete tunnel lining surface crack detection by removing the lining seam.

Alphonsus crater - Floor fracture and dark-mantle deposit distribution from new 3.0-cm radar images

NASA Technical Reports Server (NTRS)

Zisk, Stanley H.; Campbell, Bruce C.; Pettengill, Gordon H.; Brockelman, Richard

1991-01-01

The lunar crater Alphonsus is characterized by numerous fractures or graben, and by endogenic dark-halo craters. Existing maps of fractures from analysis of lunar photography may be biased by the east-west solar illumination. This paper presents new high-resolution, dual-polarization 3.0-cm wavelength radar images of Alphonsus with radar illumination from northerly directions, and uses these data to better map the locations of both the graben and a variety of dark-mantle deposits. The distribution of fractures, and several graben which cut the crater floor and central ridge, are cited as possible evidence for simultaneous, post-Imbrium uplift of both structures. Some of the endogenic dark halo deposits are more extensive in depolarized radar images than in photographs; these extensions are attributed in some cases to more distant emplacement of pyroclastic material, and in others to fortuitous connections with smoother, less cratered portions of the Alphonsus floor.

Folding kinematics expressed in fracture patterns: An example from the Anti-Atlas fold belt, Morocco

NASA Astrophysics Data System (ADS)

Ismat, Zeshan

2008-11-01

The Anti-Atlas fold belt, Morocco, formed during the same Variscan collisional event that produced the Valley-and-Ridge fold-thrust belt of the Appalachian mountains. Both are external belts of the Appalachian-Ouachita-Mauritanides chain and at the map scale have very similar topographic expressions. The Anti-Atlas, however, consists of map-scale folds that are buckle-related, detachment folds, whereas the Valley-and-Ridge folds developed in response to imbricate thrusting. For this reason, the Anti-Atlas is referred to as a fold belt rather than a fold-thrust belt. This paper examines Variscan folding processes in the Anti-Atlas Mountains. Folding in some layers occurred by sliding along a penetrative network of mesoscale fractures, i.e. cataclastic flow, during buckling. Layer-parallel shortening fractures were reactivated in the later stages of folding to accommodate limb rotation. Although 'boutonnieres', i.e. basement uplifts, punctuate the fold belt, the fracture patterns indicate that the uplifts failed to provide any 'bending' component. Folding is also interpreted to occur under low to moderate confining pressures because the fracture network includes conjugate shear fractures with very small (˜20°) dihedral angles.

Preliminary Stratigraphic Basis for Geologic Mapping of Venus

NASA Technical Reports Server (NTRS)

Basilevsky, A. T.; Head, J. W.

1993-01-01

The age relations between geologic formations have been studied at 36 1000x1000 km areas centered at the dark paraboloid craters. The geologic setting in all these sites could be characterized using only 16 types of features and terrains (units). These units form a basic stratigraphic sequence (from older to younger: (1) Tessera (Tt); (2-3) Densely fractured terrains associated with coronae (COdf) and in the form of remnants among plains (Pdf); (4) Fractured and ridged plains (Pfr); (5) Plains with wrinkle ridges (Pwr); (6-7) Smooth and lobate plains (Ps/Pl); and (8) Rift-associated fractures (Fra). The stratigraphic position of the other units is determined by their relation with the units of the basic sequence: (9) Ridge bells (RB), contemporary with Pfr; (10-11) Ridges of coronae and arachnoids annuli (COar/Aar), contemporary with wrinkle ridges of Pwr; (12) Fractures of coronae annuli (COaf) disrupt Pwr and Ps/Pl; (13) Fractures (F) disrupt Pwr or younger units; (14) Craters with associated dark paraboloids (Cdp), which are on top of all volcanic and tectonic units except the youngest episodes of rift-associated fracturing and volcanism; (15-16) Surficial streaks (Ss) and surficial patches (Sp) are approximately contemporary with Cdp. These units may be used as a tentative basis for the geologic mapping of Venus including VMAP. This mapping should test the stratigraphy and answer the question of whether this stratigraphic sequence corresponds to geologic events which were generally synchronous all around the planet or whether the sequence is simply a typical sequence of events which occurred in different places at diffferent times.

Application of thematic mapper imagery to oil exploration in Austin Chalk, central Gulf Coast basin, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reid, W.M.

1988-02-01

One of the newest major oil plays in the Gulf Coast basin, the Austin Chalk reportedly produces in three belts: an updip belt, where production is from fractured chalk in structurally high positions along faults above 7000 ft; a shallow downdip belt, where the chalk is uniformly saturated with oil from 7000 to 9000 ft; and a deeper downdip belt saturated with gas and condensate below 9000 ft. The updip fields usually occur on the southeastern, upthrown side of the Luling, Mexia, and Charlotte fault zones. Production is from fractures that connect the relatively sparse matrix pores with more permeablemore » fracture systems. The fractures resulted from regional extensional stress during the opening of the Gulf Coast basin on the divergent margin of the North American plate during the Laramide orogeny. The fractures are more common in the more brittle chalk than in the overlying Navarro and underlying Eagle Ford shales, which are less brittle. The oil in the updip traps in the chalk may have been generated in place downdip, and migrated updip along the extension fractures into the updip traps during or after the Laramide orogeny. A fairway of previously unmapped updip faults and drag folds has been mapped using Thematic Mapper imagery and seismic, structural, and resistivity maps near the Nixon field, Burleson County, Texas. This fairway, prospective for oil from the Austin Chalk, contains wells reported to produce from the Austin Chalk which lie along lineaments and linear features on the Thematic Mapper imagery and faults in the seismic and structure maps.« less

Study of application of ERTS-A imagery to fracture-related mine safety hazards in the coal mining industry

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J. (Principal Investigator); Russell, O. R.; Amato, R. V.; Leshendok, T.

1973-01-01

The author has identified the following significant results. The Kings Station Mine in Gibson County, Indiana has experienced considerable roof fall problems. Detailed fracture mapping of the mine area was done with ERTS-1 and aircraft imagery, and a prediction map of roof problem areas was produced in advance of a visit. The visit to the mine and discussions with the operator indicated that of four zones mapped as potential problem areas, three coincided with areas of excessive roof fall. This positive correlation of 75% lends confidence to the validity of the technique being applied in the investigation. The mine officials expressed an interest in the project and are anxious to see the final product maps which are forthcoming.

Wellbore pressure transducer

DOEpatents

Shuck, Lowell Z.

1979-01-01

Subterranean earth formations containing energy values are subjected to hydraulic fracturing procedures to enhance the recovery of the energy values. These fractures are induced in the earth formation by pumping liquid into the wellbore penetrating the earth formation until the pressure of the liquid is sufficient to fracture the earth formation adjacent to the wellbore. The present invention is directed to a transducer which is positionable within the wellbore to generate a signal indicative of the fracture initiation useful for providing a timing signal to equipment for seismic mapping of the fracture as it occurs and for providing a measurement of the pressure at which the fracture is initiated.

Spatial analysis of fractured rock around fault zones based on photogrammetric data

NASA Astrophysics Data System (ADS)

Deckert, H.; Gessner, K.; Drews, M.; Wellmann, J. F.

2009-04-01

The location of hydrocarbon, geothermal or hydrothermal fluids is often bound to fault zones. The fracture systems along these faults play an important role in providing pathways to fluids in the Earth's crust. Thus an evaluation of the change in permeability due to rock deformation is of particular interest in these zones. Recent advances in digital imaging using modern techniques like photogrammetry provide new opportunities to view, analyze and present high resolution geological data in three dimensions. Our method is an extension of the one-dimensional scan-line approach to quantify discontinuities in rock outcrops. It has the advantage to take into account a larger amount of spatial data than conventional manual measurement methods. It enables to recover the entity of spatial information of a 3D fracture pattern, i.e. position, orientation, extent and frequency of fractures. We present examples of outcrop scale datasets in granitic and sedimentary rocks and analyse changes in fracture patterns across fault zones from the host rock to the damage zone. We also present a method to generate discontinuity density maps from 3D surface models generated by digital photogrammetry methods. This methodology has potential for application in rock mass characterization, structural and tectonic studies, the formation of hydrothermal mineral deposits, oil and gas migration, and hydrogeology. Our analysis methods represent important steps towards developing a toolkit to automatically detect and interpret spatial rock characteristics, by taking advantage of the large amount of data that can be collected by photogrammetric methods. This acquisition of parameters defining a 3D fracture pattern allows the creation of synthetic fracture networks following these constraints. The mathematical description of such a synethtical network can be implemented into numerical simulation tools for modeling fluid flow in fracture media. We give an outline of current and future applications of photogrammetry in rock mechanics, petroleum geology, hydrogeology, and structural geology.

Impact of Stress on Anomalous Transport in Fractured Rock

NASA Astrophysics Data System (ADS)

Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.

2016-12-01

Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the large heterogeneity of fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transport through fractured rock remains largely unexplored. The link between anomalous (non-Fickian) transport and confining stress has been shown only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of confining stress on flow and transport through discrete fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM), which can capture the deformation of matrix blocks, reactivation and propagation of cracks. We implement a joint constitutive model within the FEMDEM framework to simulate the effect of fracture roughness. We apply the model to a fracture network extracted from the geological map of an actual outcrop to obtain the aperture field at different stress conditions (Figure 1). We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture networks, and show that this anomalous behavior can be linked to the stress state of the rock. Finally, we develop an effective transport model that captures the anomalous transport through stressed fractures. Our results point to a heretofore unrecognized link between geomechanics and anomalous transport in discrete fractured networks. [1] P. K. Kang, S. Brown, and R. Juanes, Emergence of anomalous transport in stressed rough fractures. Earth and Planetary Science Letters, to appear (2016). Figure (a) Map of maximum principal stress with a vertical normal compressive stress of 3 MPa at top and bottom boundaries, and 1MPa at left and right boundaries. (b) Normal compressive stress of 15 MPa at top and bottom boundaries, and 5MPa at left and right boundaries.

Effective secondary fracture prevention: implementation of a global benchmarking of clinical quality using the IOF Capture the Fracture® Best Practice Framework tool.

PubMed

Javaid, M K; Kyer, C; Mitchell, P J; Chana, J; Moss, C; Edwards, M H; McLellan, A R; Stenmark, J; Pierroz, D D; Schneider, M C; Kanis, J A; Akesson, K; Cooper, C

2015-11-01

Fracture Liaison Services are the best model to prevent secondary fractures. The International Osteoporosis Foundation developed a Best Practice Framework to provide a quality benchmark. After a year of implementation, we confirmed that a single framework with set criteria is able to benchmark services across healthcare systems worldwide. Despite evidence for the clinical effectiveness of secondary fracture prevention, translation in the real-world setting remains disappointing. Where implemented, a wide variety of service models are used to deliver effective secondary fracture prevention. To support use of effective models of care across the globe, the International Osteoporosis Foundation's Capture the Fracture® programme developed a Best Practice Framework (BPF) tool of criteria and standards to provide a quality benchmark. We now report findings after the first 12 months of implementation. A questionnaire for the BPF was created and made available to institutions on the Capture the Fracture website. Responses from institutions were used to assign gold, silver, bronze or black (insufficient) level of achievements mapped across five domains. Through an interactive process with the institution, a final score was determined and published on the Capture the Fracture website Fracture Liaison Service (FLS) map. Sixty hospitals across six continents submitted their questionnaires. The hospitals served populations from 20,000 to 15 million and were a mix of private and publicly funded. Each FLS managed 146 to 6200 fragility fracture patients per year with a total of 55,160 patients across all sites. Overall, 27 hospitals scored gold, 23 silver and 10 bronze. The pathway for the hip fracture patients had the highest proportion of gold grading while vertebral fracture the lowest. In the first 12 months, we have successfully tested the BPF tool in a range of health settings across the globe. Initial findings confirm a significant heterogeneity in service provision and highlight the importance of a global approach to ensure high quality secondary fracture prevention services.

Automated Detection, Localization, and Classification of Traumatic Vertebral Body Fractures in the Thoracic and Lumbar Spine at CT

PubMed Central

Burns, Joseph E.; Yao, Jianhua; Muñoz, Hector

2016-01-01

Purpose To design and validate a fully automated computer system for the detection and anatomic localization of traumatic thoracic and lumbar vertebral body fractures at computed tomography (CT). Materials and Methods This retrospective study was HIPAA compliant. Institutional review board approval was obtained, and informed consent was waived. CT examinations in 104 patients (mean age, 34.4 years; range, 14–88 years; 32 women, 72 men), consisting of 94 examinations with positive findings for fractures (59 with vertebral body fractures) and 10 control examinations (without vertebral fractures), were performed. There were 141 thoracic and lumbar vertebral body fractures in the case set. The locations of fractures were marked and classified by a radiologist according to Denis column involvement. The CT data set was divided into training and testing subsets (37 and 67 subsets, respectively) for analysis by means of prototype software for fully automated spinal segmentation and fracture detection. Free-response receiver operating characteristic analysis was performed. Results Training set sensitivity for detection and localization of fractures within each vertebra was 0.82 (28 of 34 findings; 95% confidence interval [CI]: 0.68, 0.90), with a false-positive rate of 2.5 findings per patient. The sensitivity for fracture localization to the correct vertebra was 0.88 (23 of 26 findings; 95% CI: 0.72, 0.96), with a false-positive rate of 1.3. Testing set sensitivity for the detection and localization of fractures within each vertebra was 0.81 (87 of 107 findings; 95% CI: 0.75, 0.87), with a false-positive rate of 2.7. The sensitivity for fracture localization to the correct vertebra was 0.92 (55 of 60 findings; 95% CI: 0.79, 0.94), with a false-positive rate of 1.6. The most common cause of false-positive findings was nutrient foramina (106 of 272 findings [39%]). Conclusion The fully automated computer system detects and anatomically localizes vertebral body fractures in the thoracic and lumbar spine on CT images with a high sensitivity and a low false-positive rate. © RSNA, 2015 Online supplemental material is available for this article. PMID:26172532

Incorporation of Interfacial Intermetallic Morphology in Fracture Mechanism Map for Sn-Ag-Cu Solder Joints

NASA Astrophysics Data System (ADS)

Huang, Z.; Kumar, P.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

2014-01-01

A fracture mechanism map (FMM) is a powerful tool which correlates the fracture behavior of a material to its microstructural characteristics in an explicit and convenient way. In the FMM for solder joints, an effective thickness of the interfacial intermetallic compound (IMC) layer ( t eff) and the solder yield strength ( σ ys,eff) are used as abscissa and ordinate axes, respectively, as these two predominantly affect the fracture behavior of solder joints. Earlier, a definition of t eff, based on the uniform thickness of IMC ( t u) and the average height of the IMC scallops ( t s), was proposed and shown to aptly explain the fracture behavior of solder joints on Cu. This paper presents a more general definition of t eff that is more widely applicable to a range of metallizations, including Cu and electroless nickel immersion gold (ENIG). Using this new definition of t eff, mode I FMM for SAC387/Cu joints has been updated and its validity was confirmed. A preliminary FMM for SAC387/Cu joints with ENIG metallization is also presented.

Understanding Seismic Anisotropy in Hunt Well of Fort McMurray, Canada

NASA Astrophysics Data System (ADS)

Malehmir, R.; Schmitt, D. R.; Chan, J.

2014-12-01

Seismic imaging plays vital role in geothermal systems as a sustainable energy resource. In this paper, we acquired and processed zero-offset and walk-away VSP and logging as well as surface seismic in Athabasca oil sand area, Alberta. Seismic data were highly processed to make better image geothermal system. Through data processing, properties of natural fractures such as orientation and width were studied and high probable permeable zones were mapped along the deep drilled to the depth of 2363m deep into crystalline basement rocks. In addition to logging data, seismic data were processed to build a reliable image of underground. Velocity analysis in high resolution multi-component walk-away VSP informed us about the elastic anisotropy in place. Study of the natural and induced fracture as well as elastic anisotropy in the seismic data, led us to better map stress regime around the well bore. The seismic image and map of fractures optimizes enhanced geothermal stages through hydraulic stimulation. Keywords: geothermal, anisotropy, VSP, logging, Hunt well, seismic

A trace map comparison algorithm for the discrete fracture network models of rock masses

NASA Astrophysics Data System (ADS)

Han, Shuai; Wang, Gang; Li, Mingchao

2018-06-01

Discrete fracture networks (DFN) are widely used to build refined geological models. However, validating whether a refined model can match to reality is a crucial problem, concerning whether the model can be used for analysis. The current validation methods include numerical validation and graphical validation. However, the graphical validation, aiming at estimating the similarity between a simulated trace map and the real trace map by visual observation, is subjective. In this paper, an algorithm for the graphical validation of DFN is set up. Four main indicators, including total gray, gray grade curve, characteristic direction and gray density distribution curve, are presented to assess the similarity between two trace maps. A modified Radon transform and loop cosine similarity are presented based on Radon transform and cosine similarity respectively. Besides, how to use Bézier curve to reduce the edge effect is described. Finally, a case study shows that the new algorithm can effectively distinguish which simulated trace map is more similar to the real trace map.

Investigate feasibility of using ground penetrating radar in QC/QA of rubblization projects.

DOT National Transportation Integrated Search

2011-07-01

This study investigated if Ground Penetrating Radar can offer a suitable technology for mapping the physical condition of fractured slab rapidly, particularly under the steel reinforcement, without disturbing the fractured layer. A 4000 long compo...

Comparison of Computed Tomography and Chest Radiography in the Detection of Rib Fractures in Abused Infants

ERIC Educational Resources Information Center

Wootton-Gorges, Sandra L.; Stein-Wexler, Rebecca; Walton, John W.; Rosas, Angela J.; Coulter, Kevin P.; Rogers, Kristen K.

2008-01-01

Purpose: Chest radiographs (CXR) are the standard method for evaluating rib fractures in abused infants. Computed tomography (CT) is a sensitive method to detect rib fractures. The purpose of this study was to compare CT and CXR in the evaluation of rib fractures in abused infants. Methods: This retrospective study included all 12 abused infants…

Quantitative MR imaging in fracture dating--Initial results.

PubMed

Baron, Katharina; Neumayer, Bernhard; Widek, Thomas; Schick, Fritz; Scheicher, Sylvia; Hassler, Eva; Scheurer, Eva

2016-04-01

For exact age determinations of bone fractures in a forensic context (e.g. in cases of child abuse) improved knowledge of the time course of the healing process and use of non-invasive modern imaging technology is of high importance. To date, fracture dating is based on radiographic methods by determining the callus status and thereby relying on an expert's experience. As a novel approach, this study aims to investigate the applicability of magnetic resonance imaging (MRI) for bone fracture dating by systematically investigating time-resolved changes in quantitative MR characteristics after a fracture event. Prior to investigating fracture healing in children, adults were examined for this study in order to test the methodology for this application. Altogether, 31 MR examinations in 17 subjects (♀: 11 ♂: 6; median age 34 ± 15 y, scanned 1-5 times over a period of up to 200 days after the fracture event) were performed on a clinical 3T MR scanner (TimTrio, Siemens AG, Germany). All subjects were treated conservatively for a fracture in either a long bone or in the collar bone. Both, qualitative and quantitative MR measurements were performed in all subjects. MR sequences for a quantitative measurement of relaxation times T1 and T2 in the fracture gap and musculature were applied. Maps of quantitative MR parameters T1, T2, and magnetisation transfer ratio (MTR) were calculated and evaluated by investigating changes over time in the fractured area by defined ROIs. Additionally, muscle areas were examined as reference regions to validate this approach. Quantitative evaluation of 23 MR data sets (12 test subjects, ♀: 7 ♂: 5) showed an initial peak in T1 values in the fractured area (T1=1895 ± 607 ms), which decreased over time to a value of 1094 ± 182 ms (200 days after the fracture event). T2 values also peaked for early-stage fractures (T2=115 ± 80 ms) and decreased to 73 ± 33 ms within 21 days after the fracture event. After that time point, no significant changes could be detected for T2. MTR remained constant at 35.5 ± 8.0% over time. The study shows that the quantitative assessment of T1 and T2 behaviour over time in the fractured region enable the generation of a novel model allowing for an objective age determination of a fracture. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Seismic Characterizations of Fractures: Dynamic Diagnostics

NASA Astrophysics Data System (ADS)

Pyrak-Nolte, L. J.

2017-12-01

Fracture geometry controls fluid flow in a fracture, affects mechanical stability and influences energy partitioning that affects wave scattering. Our ability to detect and monitor fracture evolution is controlled by the frequency of the signal used to probe a fracture system, i.e. frequency selects the scales. No matter the frequency chosen, some set of discontinuities will be optimal for detection because different wavelengths sample different subsets of fractures. The select subset of fractures is based on the stiffness of the fractures which in turn is linked to fluid flow. A goal is obtaining information from scales outside the optimal detection regime. Fracture geometry trajectories are a potential approach to drive a fracture system across observation scales, i.e. moving systems between effective medium and scattering regimes. Dynamic trajectories (such as perturbing stress, fluid pressure, chemical alteration, etc.) can be used to perturb fracture geometry to enhance scattering or give rise to discrete modes that are intimately related to the micro-structural evolution of a fracture. However, identification of these signal features will require methods for identifying these micro-structural signatures in complicated scattered fields. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022).

Use of the high-resolution satellite images for detection of fractures related to the ore deposits

NASA Astrophysics Data System (ADS)

Cruz-Mondaca, M.; Soto-Pinto, C. A.; Arellano-Baeza, A. A.

2012-12-01

The Aster and GeoEye satellite high-resolution images were used to detect the structures related to the fracturing of the upper crust in the North of Chile. In particular, lineament analysis has been applied to detect the presence of epithermal fluids of low sulfurization associated with the Paleozoic ore deposits. These results have been compared with the location of the minerals altered by the presence of geothermal fluids detected using the spectral libraries. Later, the presence of fractures has been corroborated during recognition of fractures in situ and the geochemical analysis of samples of minerals altered by the presence of fluids. It was shown that the results obtained are relevant for the gold vein detection.

Preliminary Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut

USGS Publications Warehouse

Walsh, Gregory J.; Scott, Robert B.; Aleinikoff, John N.; Armstrong, Thomas R.

2006-01-01

This report presents a preliminary map of the bedrock geology of the Old Lyme quadrangle, New London and Middlesex Counties, Connecticut. The map depicts contacts of bedrock geologic units, faults, outcrops, and structural geologic information. The map was published as part of a study of fractured bedrock aquifers and regional tectonics.

Integrating GIS-based geologic mapping, LiDAR-based lineament analysis and site specific rock slope data to delineate a zone of existing and potential rock slope instability located along the grandfather mountain window-Linville Falls shear zone contact, Southern Appalachian Mountains, Watauga County, North Carolina

USGS Publications Warehouse

Gillon, K.A.; Wooten, R.M.; Latham, R.L.; Witt, A.W.; Douglas, T.J.; Bauer, J.B.; Fuemmeler, S.J.

2009-01-01

Landslide hazard maps of Watauga County identify >2200 landslides, model debris flow susceptibility, and evaluate a 14km x 0.5km zone of existing and potential rock slope instability (ZEPRSI) near the Town of Boone. The ZEPRSI encompasses west-northwest trending (WNWT) topographic ridges where 14 active/past-active rock/weathered rock slides occur mainly in rocks of the Grandfather Mountain Window (GMW). The north side of this ridgeline is the GMW / Linville Falls Fault (LFF) contact. Sheared rocks of the Linville Falls Shear Zone (LFSZ) occur along the ridge and locally in the valley north of the contact. The valley is underlain principally by layered granitic gneiss comprising the Linville Falls/Beech Mountain/Stone Mountain Thrust Sheet. The integration of ArcGIS??? - format digital geologic and lineament mapping on a 6m LiDAR (Light Detecting and Ranging) digital elevation model (DEM) base, and kinematic analyses of site specific rock slope data (e.g., presence and degree of ductile and brittle deformation fabrics, rock type, rock weathering state) indicate: WNWT lineaments are expressions of a regionally extensive zone of fractures and faults; and ZEPRSI rock slope failures concentrate along excavated, north-facing LFF/LFSZ slopes where brittle fabrics overprint older metamorphic foliations, and other fractures create side and back release surfaces. Copyright 2009 ARMA, American Rock Mechanics Association.

Remote sensing detection of gold related alteration zones in Um Rus area, Central Eastern Desert of Egypt

NASA Astrophysics Data System (ADS)

Amer, Reda; Kusky, Timothy; El Mezayen, Ahmed

2012-01-01

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Phased Array L-band Synthetic Aperture Radar (PALSAR) images covering the Um Rus area in the Central Eastern Desert of Egypt were evaluated for mapping geologic structure, lithology, and gold-related alteration zones. The study area is covered by Pan-African basement rocks including gabbro and granodiorite intruded into a variable mixture of metavolcanics and metasediments. The first three principal component analyses (PCA1, PCA2, PCA3) in a Red-Green-Blue (RGB) of the visible through shortwave-infrared (VNIR + SWIR) ASTER bands enabled the discrimination between lithological units. The results show that ASTER band ratios ((2 + 4)/3, (5 + 7)/6, (7 + 9)/8) in RGB identifies the lithological units and discriminates the granodiorite very well from the adjacent rock units.The granodiorites are dissected by gold-bearing quartz veins surrounded by alteration zones. The microscopic examination of samples collected from the alteration zones shows sericitic and argillic alteration zones. The Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) supervised classification methods were applied using the reference spectra of the USGS spectral library. The results show that these classification methods are capable of mapping the alteration zones as indicated by field verification work. The PALSAR image was enhanced for fracture mapping using the second moment co-occurrence filter. Overlying extracted faults and alteration zone classification images show that the N30E and N-S fractures represent potential zones for gold exploration. It is concluded that the proposed methods can be used as a powerful tool for ore deposit exploration.

Bone scan as a screening test for missed fractures in severely injured patients.

PubMed

Lee, K-J; Jung, K; Kim, J; Kwon, J

2014-12-01

In many cases, patients with severe blunt trauma have multiple fractures throughout the body. These fractures are not often detectable by history or physical examination, and their diagnosis can be delayed or even missed. Thus, screening test fractures of the whole body is required after initial management. We performed this study to evaluate the reliability of bone scans for detecting missed fractures in patients with multiple severe traumas and we analyzed the causes of missed fractures by using bone scan. A bone scan is useful as a screening test for fractures of the entire body of severe trauma patients who are passed the acute phase. We reviewed the electronic medical records of severe trauma patients who underwent a bone scan from September 2009 to December 2010. Demographic and medical data were compared and statistically analyzed to determine whether missed fractures were detected after bone scan in the two groups. A total of 382 patients who had an injury severity score [ISS] greater than 16 points with multiple traumas visited the emergency room. One hundred and thirty-one patients underwent bone scan and 81 patients were identified with missed fractures by bone scan. The most frequent location for missed fractures was the rib area (55 cases, 41.98%), followed by the extremities (42 cases, 32.06%). The missed fractures that required surgery or splint were most common in extremities (11 cases). In univariate analysis, higher ISS scores and mechanism of injury were related with the probability that missed fractures would be found with a bone scan. The ISS score was statistically significant in multivariate analysis. Bone scan is an effective method of detecting missed fractures among patients with multiple severe traumas. Level IV, retrospective study. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Groundwater favorability map using GIS multicriteria data analysis on crystalline terrain, São Paulo State, Brazil

NASA Astrophysics Data System (ADS)

Madrucci, Vanessa; Taioli, Fabio; de Araújo, Carlos César

2008-08-01

SummaryThis paper presents the groundwater favorability mapping on a fractured terrain in the eastern portion of São Paulo State, Brazil. Remote sensing, airborne geophysical data, photogeologic interpretation, geologic and geomorphologic maps and geographic information system (GIS) techniques have been used. The results of cross-tabulation between these maps and well yield data allowed groundwater prospective parameters in a fractured-bedrock aquifer. These prospective parameters are the base for the favorability analysis whose principle is based on the knowledge-driven method. The multicriteria analysis (weighted linear combination) was carried out to give a groundwater favorability map, because the prospective parameters have different weights of importance and different classes of each parameter. The groundwater favorability map was tested by cross-tabulation with new well yield data and spring occurrence. The wells with the highest values of productivity, as well as all the springs occurrence are situated in the excellent and good favorability mapped areas. It shows good coherence between the prospective parameters and the well yield and the importance of GIS techniques for definition of target areas for detail study and wells location.

Newly designed anterolateral and posterolateral locking anatomic plates for lateral tibial plateau fractures: a finite element study.

PubMed

Chen, Pengbo; Lu, Hua; Shen, Hao; Wang, Wei; Ni, Binbin; Chen, Jishizhan

2017-02-23

Lateral column tibial plateau fracture fixation with a locking screw plate has higher mechanical stability than other fixation methods. The objectives of the present study were to introduce two newly designed locking anatomic plates for lateral tibial plateau fracture and to demonstrate their characteristics of the fixation complexes under the axial loads. Three different 3D finite element models of the lateral tibial plateau fracture with the bone plates were created. Various axial forces (100, 500, 1000, and 1500 N) were applied to simulate the axial compressive load on an adult knee during daily life. The equivalent maps of displacement and stress were output, and relative displacement was calculated along the fracture lines. The displacement and stresses in the fixation complexes increased with the axial force. The equivalent displacement or stress map of each fixation under different axial forces showed similar distributing characteristics. The motion characteristics of the three models differed, and the max-shear stress of trabecula increased with the axial load. These two novel plates could fix lateral tibial plateau fractures involving anterolateral and posterolateral fragments. Motions after open reduction and stable internal fixation should be advised to decrease the risk of trabecular microfracture. The relative displacement of the posterolateral fragments is different when using anterolateral plate and posterolateral plate, which should be considered in choosing the implants for different posterolateral plateau fractures.

Frequency of rib and sternum fractures associated with out-of-hospital cardiopulmonary resuscitation is underestimated by conventional chest X-ray.

PubMed

Lederer, Wolfgang; Mair, Dieter; Rabl, Walter; Baubin, Michael

2004-02-01

Fractured ribs and sternum are frequent complications of thoracic compression during CPR in adults. This study was conducted to determine whether findings of plain chest radiography (CXR) correlate with post-mortem findings in patients who underwent cardiopulmonary resuscitation (CPR) after out-of-hospital cardiac arrest. CXR findings and autopsy results of CPR-related chest injuries comprising rib and sternum fractures were compared prospectively in 19 patients. Fractures were diagnosed in nine of 19 patients by means of radiology and in 18 of 19 patients by autopsy (rib fractures in 6/19 versus 17/19, P=0.002; sternum fractures in 5/19 versus in 9/19, P=0.227. The total number of isolated bone fractures detected by CXR was 18 (12 rib and six sternum fractures) and by autopsy 92 (83 rib and nine sternum fractures). The majority of rib fractures was located in the anterior part of the thoracic cage. Sternum fractures predominantly occurred in the lower third. Eight of 19 patients received either thrombolytic or antithrombotic treatment during CPR but no major bleeding complication associated with CPR was detected by autopsy. The findings of this study indicate that fractures associated with CPR are underreported in conventional radiographic investigations. No major bleeding complications related to CPR-associated fractures was detected.

Beyond Single Images: Combining the Geosciences in Geothermal Exploration

NASA Astrophysics Data System (ADS)

Malin, P. E.

2012-12-01

Geothermal exploration routinely includes a variety of field surveys, the interpretations of which are usually done separately and then combined in some ad hoc way. Instead, because these data share numerous constraints, combining them in a systematic, quantitative way is far preferable. Aside from the shared geological background, a "joint" analysis can dampen errors and noise in one data set by less sensitive responses in another. In this presentation case histories from several surveys will be used to illustrate these points. By way of background, an example of this type of integrated approach is the improvement in earthquake location when P-wave data are supplemented with S-wave data. These two waves share the effects of the S-wave velocity structure through its shear modulus, which the S-wave measures independent of the P-wave. Using only P-waves travel times for event location is thus equivalent to making the acoustic approximation for the elastic rock velocities. When earthquake location combines both phases, not only is this approximation improved, but errors in picking these times are reduced as well. The case histories include 1) mapping fracture orientations -primarily using seismic shear wave splitting and magnetotelluric polarization directions, but supplemented with surface geology and 2) deriving combined porosity and permeability from seismic velocity and resistivity. Shear wave splitting is routinely used to detect fracture orientation since S-waves propagate faster parallel to their direction. However shear wave splitting can also be caused by other features such as 2-D layering. Magnetotelluric polarizations can be the result of fracture orientation, but also with 3-D structural effects. However, combined, the non-fracture related effects are notably different between the two data types. As a result, detecting similar polarization effects in both makes the case for aligned fractures strong. In a similar vein, porosity and permeability play different roles in determining the relationships between seismic velocities and electrical conductivities. Velocities are more sensitive to rocks with different lithology and porosity while electrical conductivities are more sensitive to rocks with different permeability. Change in seismic velocity due to rock density or lithology have less of an effect on electrical conductivity as compared to a similar change in seismic velocity due to porosity. Similarly, a large fluctuation in electrical conductivity is more logically attributed to variation in permeability. The joint quantitative analysis of such data sets includes using, for example, simple linear and more advanced inversion schemes. Combining their inversion creates a subsurface map that is more robust than with either method alone. The combination of sensitivities helps constrain local fluctuations in these properties as well as background noise. The final test is of course in the drilling, recent results of which support the approach described here.

Dynamic Behavior and Optimization of Advanced Armor Ceramics: January-December 2011 Annual Report

DTIC Science & Technology

2015-03-01

however, under conventional methods of processing. To develop plasticity in ceramic like SiC, new fracture mechanisms and interesting behaviors need...and new fracture mechanisms . These improvements, in turn, could offer the potential for improved ballistic performance. Co-precipitation has been...experiments, the following deformed fragments were recovered for extensive SEM and TEM study.  A fracture mechanism map has been constructed in

Directional semivariogram analysis to identify and rank controls on the spatial variability of fracture networks

NASA Astrophysics Data System (ADS)

Hanke, John R.; Fischer, Mark P.; Pollyea, Ryan M.

2018-03-01

In this study, the directional semivariogram is deployed to investigate the spatial variability of map-scale fracture network attributes in the Paradox Basin, Utah. The relative variability ratio (R) is introduced as the ratio of integrated anisotropic semivariogram models, and R is shown to be an effective metric for quantifying the magnitude of spatial variability for any two azimuthal directions. R is applied to a GIS-based data set comprising roughly 1200 fractures, in an area which is bounded by a map-scale anticline and a km-scale normal fault. This analysis reveals that proximity to the fault strongly influences the magnitude of spatial variability for both fracture intensity and intersection density within 1-2 km. Additionally, there is significant anisotropy in the spatial variability, which is correlated with trends of the anticline and fault. The direction of minimum spatial correlation is normal to the fault at proximal distances, and gradually rotates and becomes subparallel to the fold axis over the same 1-2 km distance away from the fault. We interpret these changes to reflect varying scales of influence of the fault and the fold on fracture network development: the fault locally influences the magnitude and variability of fracture network attributes, whereas the fold sets the background level and structure of directional variability.

Bedrock Geologic Map of the Headwaters Region of the Cullasaja River, Macon and Jackson Counties, North Carolina

USGS Publications Warehouse

Burton, William C.

2007-01-01

The headwaters region of the Cullasaja River is underlain by metasedimentary and meta-igneous rocks of the Neoproterozoic Ashe Metamorphic Suite, including gneiss, schist, and amphibolite, that were intruded during Ordovician time by elongate bodies of trondhjemite, a felsic plutonic rock. Deformation, metamorphism, and intrusion occurred roughly simultaneously during the Taconic orogeny, about 470 million years ago, under upper-amphibolite-facies metamorphic conditions. Two generations of foliation and three major phases of folds are recognized. The second- and third-generation folds trend northeast and exert the most control on regional foliation trends. Since the orogeny, the region has undergone uplift, fracturing, and erosion. Resistance to erosion by the plutonic rock may be the primary reason for the relatively gentle relief of the high-elevation basin, compared to surrounding areas. Amphibolite is the most highly fractured lithology, followed by trondhjemite; the latter may have the best ground-water potential of the mapped lithologies by virtue of its high fracture density and high proportion of subhorizontal fractures.

CT-scout based, semi-automated vertebral morphometry after digital image enhancement.

PubMed

Glinkowski, Wojciech M; Narloch, Jerzy

2017-09-01

Radiographic diagnosis of osteoporotic vertebral fracture is necessary to reduce its substantial associated morbidity. Computed tomography (CT) scout has recently been demonstrated as a reliable technique for vertebral fracture diagnosis. Software assistance may help to overcome some limitations of that diagnostics. We aimed to evaluate whether digital image enhancement improved the capacity of one of the existing software to detect fractures semi-automatically. CT scanograms of patients suffering from osteoporosis, with or without vertebral fractures were analyzed. The original set of CT scanograms were triplicated and digitally modified to improve edge detection using three different techniques: SHARPENING, UNSHARP MASKING, and CONVOLUTION. The manual morphometric analysis identified 1485 vertebrae, 200 of which were classified as fractured. Unadjusted morphometry (AUTOMATED with no digital enhancement) found 63 fractures, 33 of which were true positive (i.e., it correctly identified 52% of the fractures); SHARPENING detected 57 fractures (30 true positives, 53%); UNSHARP MASKING yielded 30 (13 true positives, 43%); and CONVOLUTION found 24 fractures (9 true positives, 38%). The intra-reader reliability for height ratios did not significantly improve with image enhancement (kappa ranged 0.22-0.41 for adjusted measurements and 0.16-0.38 for unadjusted). Similarly, the inter-reader agreement for prevalent fractures did not significantly improve with image enhancement (kappa 0.29-0.56 and -0.01 to 0.23 for adjusted and unadjusted measurements, respectively). Our results suggest that digital image enhancement does not improve software-assisted vertebral fracture detection by CT scout. Copyright © 2017 Elsevier B.V. All rights reserved.

The use of radar and LANDSAT data for mineral and petroleum exploration in the Los Andes region, Venezuela

NASA Technical Reports Server (NTRS)

Vincent, R. K.

1980-01-01

A geological study of a 27,500 sq km area in the Los Andes region of northwestern Venezuela was performed which employed both X-band radar mosaics and computer processed Landsat images. The 3.12 cm wavelength radar data were collected with horizontal-horizontal polarization and 10 meter spatial resolution by an Aeroservices SAR system at an altitude of 12,000 meters. The radar images increased the number of observable suspected fractures by 27 percent over what could be mapped by LANDSAT alone, owing mostly to the cloud cover penetration capabilities of radar. The approximate eight fold greater spatial resolution of the radar images made possible the identification of shorter, narrower fractures than could be detected with LANDSAT data alone, resulting in the discovery of a low relief anticline that could not be observed in LANDSAT data. Exploration targets for petroleum, copper, and uranium were identified for further geophysical work.

Ground penetrating radar for fracture mapping in underground hazardous waste disposal sites: A case study from an underground research tunnel, South Korea

NASA Astrophysics Data System (ADS)

Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon; Um, Evan Schankee

2017-06-01

Secure disposal or storage of nuclear waste within stable geologic environments hinges on the effectiveness of artificial and natural radiation barriers. Fractures in the bedrock are viewed as the most likely passage for the transport of radioactive waste away from a disposal site. We utilize ground penetrating radar (GPR) to map fractures in the tunnel walls of an underground research tunnel at the Korea Atomic Energy Research Institute (KAERI). GPR experiments within the KAERI Underground Research Tunnel (KURT) were carried out by using 200 MHz, 500 MHz, and 1000 MHz antennas. By using the high-frequency antennas, we were able to identify small-scale fractures, which were previously unidentified during the tunnel excavation process. Then, through 3-D visualization of the grid survey data, we reconstructed the spatial distribution and interconnectivity of the multi-scale fractures within the wall. We found that a multi-frequency GPR approach provided more details of the complex fracture network, including deep structures. Furthermore, temporal changes in reflection polarity between the GPR surveys enabled us to infer the hydraulic characteristics of the discrete fracture network developed behind the surveyed wall. We hypothesized that the fractures exhibiting polarity change may be due to a combination of air-filled and mineralogical boundaries. Simulated GPR scans for the considered case were consistent with the observed GPR data. If our assumption is correct, the groundwater flow into these near-surface fractures may form the water-filled fractures along the existing air-filled ones and hence cause the changes in reflection polarity over the given time interval (i.e., 7 days). Our results show that the GPR survey is an efficient tool to determine fractures at various scales. Time-lapse GPR data may be essential to characterize the hydraulic behavior of discrete fracture networks in underground disposal facilities.

Sensitivity of autopsy and radiological examination in detecting bone fractures in an animal model: implications for the assessment of fatal child physical abuse.

PubMed

Cattaneo, C; Marinelli, E; Di Giancamillo, A; Di Giancamillo, M; Travetti, O; Vigano', L; Poppa, P; Porta, D; Gentilomo, A; Grandi, M

2006-12-20

Skeletal injuries are often strong indicators of child abuse and their detection is therefore crucial. The aim of this study was to compare the sensitivity of three diagnostic approaches, namely autopsy, traditional (conventional) radiology, and computed tomography on "battered" piglets, in order to verify the sensitivity of each method, with respect to the true number of bone fractures assessed once the piglet was skeletonised (osteological control). Four newborn cadaver piglets who had died from natural causes were severely beaten post-mortem in every district of the body. Traditional radiography, computed tomography (CT) and autopsy were performed. The piglet was then macerated until skeletonised and the number of all fractures present recorded (osteological control). On the cranium, traditional radiology revealed only 35% circa of actual fractures, autopsy detected only 31% (P<0.01 for both comparisons versus osteological control), whereas CT imaging detected all fractures actually present. For ribs, radiology detected only 47% of all fractures present, and autopsy 65% circa (P>0.05 for both comparisons versus osteological control), while CT scans detected 34% (P<0.01). In suspected cases of fatal child abuse, we suggest that the bones of specific districts be directly analysed either at autopsy or by collecting specific diagnostic sites, such as parts of the rib cage, and subjecting them to maceration. The removed areas could be replaced with artificial material for cosmetic purposes. The authors stress the importance of combined radiological, CT scan, autopsy and osteological survey in the detection of perimortem bone fractures.

Characteristics of bone fractures and usefulness of micro-computed tomography for fracture detection in rabbits: 210 cases (2007-2013).

PubMed

Sasai, Hiroshi; Fujita, Daisuke; Tagami, Yukari; Seto, Eiko; Denda, Yuki; Hamakita, Hideaki; Ichihashi, Tomonori; Okamura, Kensaku; Furuya, Masaru; Tani, Hiroyuki; Sasai, Kazumi; Yamate, Jyoji

2015-06-15

To characterize bone fractures and the usefulness of micro-CT for imaging fractures in pet rabbits. Retrospective case series. 210 client-owned rabbits with bone fractures. Medical records of rabbits evaluated for bone fractures from 2007 through 2013 were examined. Information was collected on signalment and nature of fractures, and radiographic and micro-CT images of fractures were reviewed. Almost half (n = 95 [47.7%]) of fractures were in rabbits < 3 years old. Accidental fall was the most common cause. Vertebral fracture was the most common type of fracture with a nonneoplastic cause (n = 46 [23.2%]) and was most common in the L4-L7 region. The tibia was the most common site for limb fracture among all fractures with a nonneoplastic cause (45 [22.7%]). Twelve (5.7%) fractures had a neoplastic cause, and 7 of these were associated with metastatic uterine adenocarcinoma. Females were significantly more likely to have a fracture caused by neoplasia than were males. Compared with radiography, micro-CT provided more detailed fracture information, particularly for complicated fractures or structures (eg, skull, pelvic, vertebral, and comminuted limb fractures). Findings were useful for understanding the nature of fractures in pet rabbits and supported the use of micro-CT versus radiography for fracture detection and evaluation.

Madagascar's escape from Africa: A high-resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal

NASA Astrophysics Data System (ADS)

Phethean, Jordan J. J.; Kalnins, Lara M.; van Hunen, Jeroen; Biffi, Paolo G.; Davies, Richard J.; McCaffrey, Ken J. W.

2016-12-01

Accurate reconstructions of the dispersal of supercontinent blocks are essential for testing continental breakup models. Here, we provide a new plate tectonic reconstruction of the opening of the Western Somali Basin during the breakup of East and West Gondwana. The model is constrained by a new comprehensive set of spreading lineaments, detected in this heavily sedimented basin using a novel technique based on directional derivatives of free-air gravity anomalies. Vertical gravity gradient and free-air gravity anomaly maps also enable the detection of extinct mid-ocean ridge segments, which can be directly compared to several previous ocean magnetic anomaly interpretations of the Western Somali Basin. The best matching interpretations have basin symmetry around the M0 anomaly; these are then used to temporally constrain our plate tectonic reconstruction. The reconstruction supports a tight fit for Gondwana fragments prior to breakup, and predicts that the continent-ocean transform margin lies along the Rovuma Basin, not along the Davie Fracture Zone (DFZ) as commonly thought. According to our reconstruction, the DFZ represents a major ocean-ocean fracture zone formed by the coalescence of several smaller fracture zones during evolving plate motions as Madagascar drifted southwards, and offshore Tanzania is an obliquely rifted, rather than transform, margin. New seismic reflection evidence for oceanic crust inboard of the DFZ strongly supports these conclusions. Our results provide important new constraints on the still enigmatic driving mechanism of continental rifting, the nature of the lithosphere in the Western Somali Basin, and its resource potential.

Compression fractures detection on CT

NASA Astrophysics Data System (ADS)

Bar, Amir; Wolf, Lior; Bergman Amitai, Orna; Toledano, Eyal; Elnekave, Eldad

2017-03-01

The presence of a vertebral compression fracture is highly indicative of osteoporosis and represents the single most robust predictor for development of a second osteoporotic fracture in the spine or elsewhere. Less than one third of vertebral compression fractures are diagnosed clinically. We present an automated method for detecting spine compression fractures in Computed Tomography (CT) scans. The algorithm is composed of three processes. First, the spinal column is segmented and sagittal patches are extracted. The patches are then binary classified using a Convolutional Neural Network (CNN). Finally a Recurrent Neural Network (RNN) is utilized to predict whether a vertebral fracture is present in the series of patches.

Application of gamma ray spectrometric measurements and VLF-EM data for tracing vein type uranium mineralization

NASA Astrophysics Data System (ADS)

Gaafar, Ibrahim

2015-12-01

This study is an attempt to use the gamma ray spectrometric measurements and VLF-EM data to identify the subsurface structure and map uranium mineralization along El Sela shear zone, South Eastern Desert of Egypt. Many injections more or less mineralized with uranium and associated with alteration processes were recorded in El Sela shear zone. As results from previous works, the emplacement of these injections is structurally controlled and well defined by large shear zones striking in an ENE-WSW direction and crosscut by NW-SE to NNW-SSE fault sets. VLF method has been applied to map the structure and the presence of radioactive minerals that have been delineated by the detection of high uranium mineralization. The electromagnetic survey was carried out to detect the presence of shallow and deep conductive zones that cross the granites along ENE-WSW fracturing directions and to map its spatial distribution. The survey comprised seventy N-S spectrometry and VLF-EM profiles with 20 m separation. The resulted data were displayed as composite maps for K, eU and eTh as well as VLF-Fraser map. Twelve profiles with 100 m separation were selected for detailed description. The VLF-EM data were interpreted qualitatively as well as quantitatively using the Fraser and the Karous-Hjelt filters. Fraser filtered data and relative current density pseudo-sections indicate the presence of shallow and deep conductive zones that cross the granites along ENE-WSW shearing directions. High uranium concentrations found just above the higher apparent current-density zones that coincide with El-Sela shear zone indicate a positive relation between conductivity and uranium minerals occurrence. This enables to infer that the anomalies detected by VLF-EM data are due to the highly conductive shear zone enriched with uranium mineralization extending for more than 80 m.

Fracture identification based on remote detection acoustic reflection logging

NASA Astrophysics Data System (ADS)

Zhang, Gong; Li, Ning; Guo, Hong-Wei; Wu, Hong-Liang; Luo, Chao

2015-12-01

Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away from the borehole. Remote acoustic logging uses phase-controlled array-transmitting and long sound probes that increase the depth of investigation. The interpretation of logging data with respect to fractures is typically guided by practical experience rather than theory and is often ambiguous. We use remote acoustic reflection logging data and high-order finite-difference approximations in the forward modeling and prestack reverse-time migration to image fractures. First, we perform forward modeling of the fracture responses as a function of the fracture-borehole wall distance, aperture, and dip angle. Second, we extract the energy intensity within the imaging area to determine whether the fracture can be identified as the formation velocity is varied. Finally, we evaluate the effect of the fracture-borehole distance, fracture aperture, and dip angle on fracture identification.

Diagnostic Accuracy of Full-Body Linear X-Ray Scanning in Multiple Trauma Patients in Comparison to Computed Tomography.

PubMed

Jöres, A P W; Heverhagen, J T; Bonél, H; Exadaktylos, A; Klink, T

2016-02-01

The purpose of this study was to evaluate the diagnostic accuracy of full-body linear X-ray scanning (LS) in multiple trauma patients in comparison to 128-multislice computed tomography (MSCT). 106 multiple trauma patients (female: 33; male: 73) were retrospectively included in this study. All patients underwent LS of the whole body, including extremities, and MSCT covering the neck, thorax, abdomen, and pelvis. The diagnostic accuracy of LS for the detection of fractures of the truncal skeleton and pneumothoraces was evaluated in comparison to MSCT by two observers in consensus. Extremity fractures detected by LS were documented. The overall sensitivity of LS was 49.2 %, the specificity was 93.3 %, the positive predictive value was 91 %, and the negative predictive value was 57.5 %. The overall sensitivity for vertebral fractures was 16.7 %, and the specificity was 100 %. The sensitivity was 48.7 % and the specificity 98.2 % for all other fractures. Pneumothoraces were detected in 12 patients by CT, but not by LS. 40 extremity fractures were detected by LS, of which 4 fractures were dislocated, and 2 were fully covered by MSCT. The diagnostic accuracy of LS is limited in the evaluation of acute trauma of the truncal skeleton. LS allows fast whole-body X-ray imaging, and may be valuable for detecting extremity fractures in trauma patients in addition to MSCT.  The overall sensitivity of LS for truncal skeleton injuries in multiple-trauma patients was < 50 %. The diagnostic reference standard MSCT is the preferred and reliable imaging modality. LS may be valuable for quick detection of extremity fractures. © Georg Thieme Verlag KG Stuttgart · New York.

Comparison of fracture roughness and acoustic emissions statistics from triaxial deformation of rocks

NASA Astrophysics Data System (ADS)

Schmittbuhl, Jean; Heap, Michael John; Baud, Patrick; Meredith, Philip George

2010-05-01

Fracture roughness has been shown to be a very robust parameter in fracture mechanics with little sensitivity on the material properties, fracture modes, loading conditions and scales. Indeed, a self-affine scaling invariance has been show to be a very good geometrical model of the fracture surface geometry in many configurations. However some hints of departure from this general rule seem to exist in some specific cases. To re-explore this observation, we have performed a large set of triaxial tests on six different rocks, with contrasting physical properties: Etna basalt, Westerly granite, Crab Orchard sandstone, Darley Dale sandstone, Bentheim sandstone and Solnhofen limestone. All tests were performed under the same conditions: an effective confining pressure of 30MPa (50MPa confining pressure and a 20MPa pore fluid pressure), at a constant strain rate of 1.0 x 10-5 s-1, room temperature and under drained conditions. Crack damage evolution was monitored throughout each experiment by measuring the independent damage proxies of axial strain, pore volume change and output of acoustic emission (AE) energy. Immediately after macroscopic failure, samples were slowly unloaded and pressures slowly reduced to ambient conditions, in order to carefully preserve the fault plane and fault gouge. Each of the resultant fault planes were then precisely mapped using a high resolution laser profiler (resolution of a few micro-meters) to investigate the differences in fracture roughness between the different lithologies. Moreover, extended 3D maps of fracture morphology allow to tackle the possible anisotropy of the surface with respect to the fracture slip. We finally complete our analysis by investigating the link between fracture morphogenesis and the recorded AE.

Structural analysis characterization of permeability pathways across reservoir-seal interface - South-Eastern Utah; Results from integrated sedimentological, structural, and geochemical studies.

NASA Astrophysics Data System (ADS)

Petrie, E. S.; Evans, J. P.; Richey, D.; Flores, S.; Barton, C.; Mozley, P.

2015-12-01

Sedimentary rocks in the San Rafael Swell, Utah, were deformed by Laramide compression and subsequent Neogene extension. We evaluate the effect of fault damage zone morphology as a function of structural position, and changes in mechanical stratigraphy on the distribution of secondary minerals across the reservoir-seal pair of the Navajo Sandstone and overlying Carmel Formation. We decipher paleo-fluid migration and examine the effect faults and fractures have on reservoir permeability and efficacy of top seal for a range of geo-engineering applications. Map-scale faults have an increased probability of allowing upward migration of fluids along the fault plane and within the damage zone, potentially bypassing the top seal. Field mapping, mesoscopic structural analyses, petrography, and geochemical observations demonstrate that fault zone thickness increases at structural intersections, fault relay zones, fault-related folds, and fault tips. Higher densities of faults with meters of slip and dense fracture populations are present in relay zones relative to single, discrete faults. Curvature analysis of the San Rafael monocline and fracture density data show that fracture density is highest where curvature is highest in the syncline hinge and near faults. Fractures cross the reservoir-seal interface where fracture density is highest and structural diagensis includes mineralization events and bleaching and calcite and gypsum mineralization. The link between fracture distributions and structural setting implys that transmissive fractures have predictable orientations and density distributions. At the m- to cm- scale, deformation-band faults and joints in the Navajo Sandstone penetrate the reservoir-seal interface and transition into open-mode fractures in the caprock seal. Scanline analysis and petrography of veins provide evidence for subsurface mineralization and fracture reactivation, suggesting that the fractures act as loci for fluid flow through time. Heterolithic caprock seals with variable fracture distributions and morphology highlight the strong link between the variation in material properties and the response to changing stress conditions. The variable connectivity of fractures and the changes in fracture density plays a critical role in subsurface fluid flow.

Analysis of a mesoscale infiltration and water seepage test in unsaturated fractured rock: Spatial variabilities and discrete fracture patterns

USGS Publications Warehouse

Zhou, Q.; Salve, R.; Liu, H.-H.; Wang, J.S.Y.; Hudson, D.

2006-01-01

A mesoscale (21??m in flow distance) infiltration and seepage test was recently conducted in a deep, unsaturated fractured rock system at the crossover point of two underground tunnels. Water was released from a 3??m ?? 4??m infiltration plot on the floor of an alcove in the upper tunnel, and seepage was collected from the ceiling of a niche in the lower tunnel. Significant temporal and (particularly) spatial variabilities were observed in both measured infiltration and seepage rates. To analyze the test results, a three-dimensional unsaturated flow model was used. A column-based scheme was developed to capture heterogeneous hydraulic properties reflected by these spatial variabilities observed. Fracture permeability and van Genuchten ?? parameter [van Genuchten, M.T., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44, 892-898] were calibrated for each rock column in the upper and lower hydrogeologic units in the test bed. The calibrated fracture properties for the infiltration and seepage zone enabled a good match between simulated and measured (spatially varying) seepage rates. The numerical model was also able to capture the general trend of the highly transient seepage processes through a discrete fracture network. The calibrated properties and measured infiltration/seepage rates were further compared with mapped discrete fracture patterns at the top and bottom boundaries. The measured infiltration rates and calibrated fracture permeability of the upper unit were found to be partially controlled by the fracture patterns on the infiltration plot (as indicated by their positive correlations with fracture density). However, no correlation could be established between measured seepage rates and density of fractures mapped on the niche ceiling. This lack of correlation indicates the complexity of (preferential) unsaturated flow within the discrete fracture network. This also indicates that continuum-based modeling of unsaturated flow in fractured rock at mesoscale or a larger scale is not necessarily conditional explicitly on discrete fracture patterns. ?? 2006 Elsevier B.V. All rights reserved.

Detecting gear tooth fracture in a high contact ratio face gear mesh

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.; Handschuh, Robert F.; Lewicki, David G.; Decker, Harry J.

1995-01-01

This paper summarized the results of a study in which three different vibration diagnostic methods were used to detect gear tooth fracture in a high contact ratio face gear mesh. The NASA spiral bevel gear fatigue test rig was used to produce unseeded fault, natural failures of four face gear specimens. During the fatigue tests, which were run to determine load capacity and primary failure mechanisms for face gears, vibration signals were monitored and recorded for gear diagnostic purposes. Gear tooth bending fatigue and surface pitting were the primary failure modes found in the tests. The damage ranged from partial tooth fracture on a single tooth in one test to heavy wear, severe pitting, and complete tooth fracture of several teeth on another test. Three gear fault detection techniques, FM4, NA4*, and NB4, were applied to the experimental data. These methods use the signal average in both the time and frequency domain. Method NA4* was able to conclusively detect the gear tooth fractures in three out of the four fatigue tests, along with gear tooth surface pitting and heavy wear. For multiple tooth fractures, all of the methods gave a clear indication of the damage. It was also found that due to the high contact ratio of the face gear mesh, single tooth fractures did not significantly affect the vibration signal, making this type of failure difficult to detect.

Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: Second Year Results and Third Year Plan

NASA Technical Reports Server (NTRS)

Skinner, J. A., Jr.; Tanaka, K. L.; Hare, T. M.

2009-01-01

The southern Utopia highland-lowland boundary (HLB) extends >1500 km westward from Hyblaeus Dorsa to the topographic saddle that separates Isidis and Utopia Planitiae. It contains bench-like platforms that contain depressions, pitted cones (some organized into arcuate chains and thumb-print terrain), isolated domes, buried circular depressions, ring fractures, polygonal fractures, and other locally- to regionally-dispersed landforms [1-2]. The objective of this map project is to clarify the geologic evolution of the southern Utopia Planitia HLB by identifying the geologic, structural, and stratigraphic relationships of surface materials in MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247. The project was originally awarded in April, 2007 and is in its final year of support. Mapping is on-schedule and formal map submission will occur by December, 2009, with finalization anticipated by April, 2010. Herein, we (1) review specifics regarding mapping data and methods, (2) present nomenclature requests that we feel will assist with unit descriptions, (3) describe Year 2 mapping and science accomplishments, and (4) outline Year 3 technical and managerial approaches for finalizing the geologic map.

Massive hydraulic fracture mapping and characterization program. Surface potential data for Wattenberg 1975--1976 experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCann, R.P.; Bartel, L.C.; Keck, L.J.

1977-08-01

Three massive hydraulic fracture experiments for natural gas stimulation were conducted by Halliburton for AMOCO in the Wattenberg field northeast of Denver, Colorado. The experiments were conducted on three wells--Martin Hart ''E'' No. 1, Salazar G.U. No. 1, and UPRR-22P. All three wells were open hole and the fracture zone was located at a depth of approximately 8000 ft. All were treated with approximately 300,000 gal of fluid and 600,000 lb of proppant. The surface electrical potential technique was used to attempt characterization and mapping of the fracture. The noise perturbating the system consists of telluric currents, currents from industrialmore » sources, and natural local currents. It is difficult to determine the exact signal-to-noise ratio or the exact origin of the noise without exhaustive field measurements and data analysis. However, improvements have been made in the surface potential gradient technique since the early developmental stage of the diagnostic program. To aid in the interpretation of the field data, mathematical modeling efforts have been undertaken. The model utilizes the Green's function integral equation approach where the so-called half-space Green's function is used. The model calculates the potential difference that exists at the surface as a function of fracturing conditions. Data analysis indicates that the fracture orientation for all three wells lies in a SE to NW direction and that the fractures are asymmetric.« less

Multiscale analysis of the fracture pattern in granite, example of Tamariu's granite, Catalunya.

NASA Astrophysics Data System (ADS)

Bertrand, L.; LeGarzic, E.; Géraud, Y.; Diraison, M.

2012-04-01

Crystalline rocks can be the host of important fluid flow and therefore they can provide a good reservoir potential. In this kind of rocks, the matrice porosity is in general low and a large part of the permeability is governed by the fracture pattern. Thus, they are the first interest of studies in order to characterize and model the fluid flows. Actual reservoirs are underground, and the only access to the fracture pattern is with boreholes and seismic lines. Those methods are investigating different scales and dimensions: seismic is in 3D at a global scale whereas boreholes are 1D at a localized scale. To make the link between the different data, it is necessary to study field analogues where such fractured rocks are outcropping. Tamariu's granite, in Catalunya, has recently been studied as a field analogue of a fractured reservoir. The previous studies have lead to define structural blocks at different scales, linked to the regional deformation. This study's aim is to characterize the internal fracturation of a single structural block with a statistical analysis. We used one dimension scan lines at the scale of a block and 2 dimensions mapping at a more precise scale until the grain scale. The data highlighted that the fracture and fault lengths have a power law relation in 8 orders of scales. So this power law is stretching between seismic and borehole scales. Therefore, the data fit with a very good trust in the power law exponent, which is very well defined. The link between the reservoir scale faults and the internal block fracturation has also been defined in term of the structures orientation. Finally, a comparison between the 1D and 2D measurement could be done. The 1D scan lines show correctly the different fractures families but samples incompletely a part the fracture pattern, whereas the 2D maps which show more the global trends of the fractures and could lose some minor trends orientations.

Use of satellite pictures for determining major shield fractures relevant for ore prospecting, northern Finland

NASA Technical Reports Server (NTRS)

Tuominen, H. V.; Aarnisalo, J. (Principal Investigator)

1976-01-01

The author has identified the following significant results. A combined analysis of LANDSAT 1 imagery, aeromagnetic and other maps, and aerial photos has revealed a dense network of bedrock fractures in northern Finland. They form several fracturing zones, which obviously represent surficial manifestations of major fractures. The fractures follow, in general, the eight main trends of crustal shear characteristics of the Baltic Shield, but show distinct deviations from them in detail. The major fracture zones divide the bedrock into a mosaic of polygonal blocks, which in many cases coincide with the main rock units of the area and are characterized by different patterns of internal fracturing. Known mineralizations show a tendency to concentrate along the fracture zones. Optical filtering of original LANDSAT images might provide a rapid tool for the analysis of major structural trends in extensive areas such as shields or entire continents.

Correlation Between Fracture Network Properties and Stress Variability in Geological Media

NASA Astrophysics Data System (ADS)

Lei, Qinghua; Gao, Ke

2018-05-01

We quantitatively investigate the stress variability in fractured geological media under tectonic stresses. The fracture systems studied include synthetic fracture networks following power law length scaling and natural fracture patterns based on outcrop mapping. The stress field is derived from a finite-discrete element model, and its variability is analyzed using a set of mathematical formulations that honor the tensorial nature of stress data. We show that local stress perturbation, quantified by the Euclidean distance of a local stress tensor to the mean stress tensor, has a positive, linear correlation with local fracture intensity, defined as the total fracture length per unit area within a local sampling window. We also evaluate the stress dispersion of the entire stress field using the effective variance, that is, a scalar-valued measure of the overall stress variability. The results show that a well-connected fracture system under a critically stressed state exhibits strong local and global stress variabilities.

Borehole sampling of fracture populations - compensating for borehole sampling bias in crystalline bedrock aquifers, Mirror Lake, Grafton County, New Hampshire

USGS Publications Warehouse

McDonald, G.D.; Paillet, Frederick L.; Barton, C.C.; Johnson, C.D.

1997-01-01

The clustering of orientations of hydraulically conductive fractures in bedrock at the Mirror Lake, New Hampshire fractured rock study site was investigated by comparing the orientations of fracture populations in two subvertical borehole arrays with those mapped on four adjacent subvertical roadcuts. In the boreholes and the roadcuts, the orientation of fracture populations appears very similar after borehole data are compensated for undersampling of steeply dipping fractures. Compensated borehole and pavement fracture data indicate a northeast-striking population of fractures with varying dips concentrated near that of the local foliation in the adjacent rock. The data show no correlation between fracture density (fractures/linear meter) and distance from lithologic contacts in both the boreholes and the roadcuts. The population of water-producing borehole fractures is too small (28 out of 610 fractures) to yield meaningful orientation comparisons. However, the orientation of large aperture fractures (which contains all the producing fractures) contains two or three subsidiary clusters in orientation frequency that are not evident in stereographic projections of the entire population containing all aperture sizes. Further, these subsidiary orientation clusters do not coincide with the dominant (subhorizontal and subvertical) regional fracture orientations.

Bridge cable fracture detection with acoustic emission test (Conference Presentation)

NASA Astrophysics Data System (ADS)

Qu, Hongya; Li, Tiantian; Chen, Genda

2017-04-01

In this study, acoustic emission (AE) tests were conducted to detect and locate wire fracture in strands that are widely used in cable-stayed and suspension bridges. To effectively separate fracture signals from unwanted noises, distinct features of fracture, fracture-induced echo, and artificial tapping signals as well as their dependence on loading levels are characterized with short-time Fourier transform. To associate fracture scenarios with their acoustic features, two 20-foot-long ( 6.1 m) 270 ksi ( 1,862 MPa) steel strands of seven wires were tested with one wire notched off at center and support, respectively, up to 90% of its cross section area by 10% increment. Up to 80% reduction in cross section area of the notched wire, each strand was loaded to 20 kips ( 89 kN) corresponding to 35% of the minimum breaking strength and the acquired AE parameters such as hits, energy, and counts were found to change little. With a reduction of 90% of the section area of one wire, both strands were found to be fractured under approximately 16.5 kips ( 73.4 kN). The hits, energy, and counts of AE signals were all demonstrated to suddenly change with the fracture of the notched wire. However, only the counts of AE signals distributed over the length of the strands allow the localization of fracture point. The frequency band of fracture signals is significantly broader than that of either fracture-induced echo or artificial tapping noise. The time duration of artificial tapping noises is substantially longer than that of either fracture or fracture-induced echo. These distinct characteristics can be used to effectively separate fracture signals from noises for wire fracture detection and localization in practice.

Detection of cretaceous incised-valley shale for resource play, Miano gas field, SW Pakistan: Spectral decomposition using continuous wavelet transform

NASA Astrophysics Data System (ADS)

Naseer, Muhammad Tayyab; Asim, Shazia

2017-10-01

Unconventional resource shales can play a critical role in economic growth throughout the world. The hydrocarbon potential of faults/fractured shales is the most significant challenge for unconventional prospect generation. The continuous wavelet transforms (CWT) of spectral decomposition (SD) technology is applied for shale gas prospects on high-resolution 3D seismic data from the Miano area in the Indus platform, SW Pakistan. Schmoker' technique reveals high-quality shales with total organic carbon (TOC) of 9.2% distributed in the western regions. The seismic amplitude, root-mean-square (RMS), and most positive curvature attributes show limited ability to resolve the prospective fractured shale components. The CWT is used to identify the hydrocarbon-bearing faulted/fractured compartments encased within the non-hydrocarbon bearing shale units. The hydrocarbon-bearing shales experience higher amplitudes (4694 dB and 3439 dB) than the non-reservoir shales (3290 dB). Cross plots between sweetness, 22 Hz spectral decomposition, and the seismic amplitudes are found more effective tools than the conventional seismic attribute mapping for discriminating the seal and reservoir elements within the incised-valley petroleum system. Rock physics distinguish the productive sediments from the non-productive sediments, suggesting the potential for future shale play exploration.

The Importance of pH, Oxygen, and Bitumen on the Oxidation and Precipitation of Fe(III)-(oxy)hydroxides during Hydraulic Fracturing of Oil/Gas Shales

NASA Astrophysics Data System (ADS)

Jew, A. D.; Dustin, M. K.; Harrison, A. L.; Joe-Wong, C. M.; Thomas, D.; Maher, K.; Brown, G. E.; Bargar, J.

2016-12-01

Due to the rapid growth of hydraulic fracturing in the United States, understanding the cause for the rapid production drop off of new wells over the initial months of production is paramount. One possibility for the production decrease is pore occlusion caused by the oxidation of Fe(II)-bearing phases resulting in Fe(III) precipitates. To understand the release and fate of Fe in the shale systems, we reacted synthesized fracture fluid at 80oC with shale from four different geological localities (Marcellus Fm., Barnett Fm., Eagle Ford Fm., and Green River Fm.). A variety of wet chemical and synchrotron-based techniques (XRF mapping and x-ray absorption spectroscopy) were used to understand Fe release and solid phase Fe speciation. Solution pH was found to be the greatest factor for Fe release. Carbonate-poor Barnett and Marcellus shale showed rapid Fe release into solution followed by a plateau or significant drop in Fe concentrations indicating mineral precipitation. Conversely, in high carbonate shales, Eagle Ford and Green River, no Fe was detected in solution indicating fast Fe oxidation and precipitation. For all shale samples, bulk Fe EXAFS data show that a significant amount of Fe in the shales is bound directly to organic carbon. Throughout the course of the experiments inorganic Fe(II) phases (primarily pyrite) reacted while Fe(II) bound to C showed no indication of reaction. On the micron scale, XRF mapping coupled with μ-XANES spectroscopy showed that at pH < 4.0, Fe(III) bearing phases precipitated as diffuse surface precipitates of ferrihydrite, goethite, and magnetite away from Fe(II) point sources. In near circum-neutral pH systems, Fe(III)-bearing phases (goethite and hematite) form large particles 10's of μm's in diameter near Fe(II) point sources. Idealized systems containing synthesized fracturing fluid, dissolved ferrous chloride, and bitumen showed that bitumen released during reaction with fracturing fluids is capable of oxidizing Fe(II) to Fe(III) at pH's 2.0 and 7.0. This indicates that bitumen can play a large role in Fe oxidation and speciation in the subsurface. This work shows that shale mineralogy has a significant impact on the morphology and phases of Fe(III) precipitates in the subsurface which in turn can significantly impact subsurface solution flow.

Enceladus' Geysers and Small-scale Thermal Hot Spots: Spatial Correlations and Implications

NASA Astrophysics Data System (ADS)

Porco, C.; Helfenstein, P.; Goguen, J.

2016-12-01

The geysering south polar terrain (SPT) of Enceladus has been a major focus of the Cassini mission ever since Cassini's first sighting of it in images taken in early 2005 (1). A high resolution imaging survey of the region conducted over the course of seven years resulted in the identification of 100 geysers erupting from the four main fractures crossing the SPT (2). The Cassini Visual and Infrared Mapping Spectrometer (VIMS) detected enhanced thermal emission arising from these fractures and taking the form of small-scale ( ≤ 10 meter) discrete spots (3,4). Four of these hot spot observations have already been spatially associated with four geysers on the Baghdad Sulcus fracture (2). The inferred spatial correlation and small size of each hot spot eliminated shear heating along the near-surface walls of the fractures as the source of the heat and erupting materials. Instead, it was concluded that condensation of vapor (and liquid), and the deposition of latent heat, on the near-surface vent walls, and the subsequent conduction of that heat to the surface, was the source of the observed thermal emission. This indicated that the hot spots are the secondary signature of a geyser eruption process deeply rooted in the moon's sub-surface liquid water reservoir (2). We extend the examination of these relationships to include seven additional VIMS observations of hot spots. At the present time, we have associated a total of 11 VIMS hot spot observations with 13 (maybe 14) geysers distributed over all four tiger stripe fractures. It's not uncommon for the locations of multiple (often two but sometimes three) surveyed geysers to overlap within estimated uncertainties. This can occur when they have different 3D orientations, making them identifiable in our 2014 survey as distinct features; However, the raw, thermally unmodeled VIMS maps, with their (relatively) coarse resolution, may register at that location only one corresponding hot spot. It is also possible that closely overlapping clusters of geysers in the survey represent a single geyser that changes its direction over the course of an Enceladus orbit as its vent widens and narrows with the diurnally varying normal stresses. Nonetheless, future thermal modeling of these VIMS hot spots should help constrain the conditions in the near-surface vents from which the geysers erupt.

Emergency ultrasound in the detection of pediatric long-bone fractures.

PubMed

Barata, Isabel; Spencer, Robert; Suppiah, Ara; Raio, Christopher; Ward, Mary Frances; Sama, Andrew

2012-11-01

Long-bone fractures represent one of the most commonly sustained injuries following trauma and account for nearly 4% of emergency department visits in the United States each year. These fractures are associated with a significant risk of bleeding and neurovascular compromise. Delays in their identification and treatment can lead to loss of limb and even death. Although emergency physicians currently rely predominantly on radiography for the examination of long-bone injuries, emergency ultrasound has several advantages over radiography and may be useful in the identification of long-bone fractures. Ultrasound is rapid, noninvasive, and cost-effective. Unlike radiography, ultrasound does not expose children to ionizing radiation, which has been linked to cancer. The goal of this study was to assess the agreement between emergency physicians' and radiologists' final assessments of suspected long-bone fractures using emergency ultrasound and radiography, respectively, in the pediatric population. This is a prospective study involving a convenience sample of pediatric patients (<18 years of age) who presented to the emergency department of a university-affiliated, level I trauma center between March 2008 and January 2009 with at least 1 suspected long-bone fracture. Suspected fractures were characterized by swelling, erythema, and localized pain. Patients who had a history of fracture, extremity deformity, orthopedic hardware in the traumatized area, or an open fracture were excluded from this study. Each investigator received limited, focused training in the use of ultrasonography for fracture identification and localization. This training consisted of a brief didactic session and video review of normal and fractured long-bones. A total of 53 subjects (mean age, 10.2 [SD, 3.8] years; 56.6% were male) were enrolled, which corresponded to 98 ultrasound examinations. Sixty-nine scans (70.4%) involved bones of the upper extremity, and 29 (29.6%) the lower extremity. Radiography identified a total of 43 fractures. The sensitivity and specificity of ultrasound in the detection of long-bone fractures were 95.3% (95% confidence interval [CI], 82.9%-99.2%) and 85.5% (95% CI, 72.8%-93.1%), respectively, and the positive and negative predictive values were 83.7% (95% CI, 68.8%-92.2%) and 96% (95% CI, 84.9%-99.3%), respectively. Overall, ultrasound detected 100.0% of diaphyseal fractures and 27 (93.1%) of 29 end-of-bone or near-joint fractures.Radiography revealed 6 displacements that met the published criteria for reduction, all of which were also revealed by ultrasound. The overall sensitivity and specificity for ultrasound identifying the need for reduction were 100.0% (95% CI, 51.7%-100.0%) and 97.3% (95% CI, 84.2%-99.9%), respectively, and positive and negative predictive values were 85.7% (95% CI, 42.0%-99.2%) and 100.0% (95% CI, 88.0%-100.0%), respectively. Emergency department physician-performed focused ultrasound was more accurate in detecting diaphyseal fractures than in detecting fractures in the metaphysis and/or epiphysis. The high sensitivity and specificity of ultrasound in the detection of long-bone fractures and the need for reduction support the use of ultrasound in the evaluation of suspected long-bone fractures in children.

An integrated study of seismic anisotropy and the natural fracture system at the Conoco Borehole Test Facility, Kay County, Oklahoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Queen, J.H.; Rizer, W.D.

1990-07-10

A significant body of published work has developed establishing fracture-related seismic anisotropy as an observable effect. To further the understanding of seismic birefringence techniques in characterizing natural fracture systems at depth, an integrated program of seismic and geologic measurements has been conducted at Conoco's Borehole Test Facility in Kay County, Oklahoma. Birefringence parameters inferred from the seismic data are consistent with a vertical fracture model of density 0.04 striking east-northeast. That direction is subparallel to a fracture set mapped both on the surface and from subsurface data, to the in situ maximum horizontal stress, and to the inferred microfabric.

Validity of height loss as a predictor for prevalent vertebral fractures, low bone mineral density, and vitamin D deficiency.

PubMed

Mikula, A L; Hetzel, S J; Binkley, N; Anderson, P A

2017-05-01

Many osteoporosis-related vertebral fractures are unappreciated but their detection is important as their presence increases future fracture risk. We found height loss is a useful tool in detecting patients with vertebral fractures, low bone mineral density, and vitamin D deficiency which may lead to improvements in patient care. This study aimed to determine if/how height loss can be used to identify patients with vertebral fractures, low bone mineral density, and vitamin D deficiency. A hospital database search in which four patient groups including those with a diagnosis of osteoporosis-related vertebral fracture, osteoporosis, osteopenia, or vitamin D deficiency and a control group were evaluated for chart-documented height loss over an average 3 1/2 to 4-year time period. Data was retrieved from 66,021 patients (25,792 men and 40,229 women). A height loss of 1, 2, 3, and 4 cm had a sensitivity of 42, 32, 19, and 14% in detecting vertebral fractures, respectively. Positive likelihood ratios for detecting vertebral fractures were 1.73, 2.35, and 2.89 at 2, 3, and 4 cm of height loss, respectively. Height loss had lower sensitivities and positive likelihood ratios for detecting low bone mineral density and vitamin D deficiency compared to vertebral fractures. Specificity of 1, 2, 3, and 4 cm of height loss was 70, 82, 92, and 95%, respectively. The odds ratios for a patient who loses 1 cm of height being in one of the four diagnostic groups compared to a patient who loses no height was higher for younger and male patients. This study demonstrated that prospective height loss is an effective tool to identify patients with vertebral fractures, low bone mineral density, and vitamin D deficiency although a lack of height loss does not rule out these diagnoses. If significant height loss is present, the high positive likelihood ratios support a further workup.

A remote sensing evaluation of potential for sinkhole occurrence

NASA Technical Reports Server (NTRS)

Casper, J.; Ruth, B.; Degner, J. (Principal Investigator)

1981-01-01

The relationship between lowering of the water table and sinkhole development in Pierson and in Hillsborough County, Florida was investigated. The locations of recently developed (1973) collapses were examined with respect to lineaments or fracture traces that are expressed in the terrain and visible in aerial photography and satellite imagery. It was anticipated that these relationships would provide the basis for establishment of criteria for mapping those land areas that have the greatest potential for sinkhole development. A very good correlation was found between mapped lineament intersections and known location of sinkhole occurrences for both study areas. This indicates that lineament and fracture trace mapping may be very useful in locating zones with the greatest potential for sinkhole development. It is further shown that this information is quite beneficial in land use planning applications.

Analysis of ERTS imagery of Wyoming and its application to evaluation of Wyoming's natural resources

NASA Technical Reports Server (NTRS)

Houston, R. S. (Principal Investigator); Marrs, R. W.

1972-01-01

The author has identified the following significant results. The Wyoming ERTS investigation has been hindered only slightly by incomplete ERTS data sets and lack of coverage. Efforts to map cultural development, vegetation distributions, and various geomorphologic features are underway. Tectonic analysis of the Rock Springs area has isolated two linear features that may be very significant with regard to the regional structure of central Wyoming. Studies of the fracture systems of the Wind River Mountains are being completed. The fracture map, constructed from ERTS-1 interpretations, contains a great deal of structural information which was previously unavailable. Mapping of the Precambrian metasedimentary and metavolcanic terrain of the Granite Mountains is nearing completion, and interpretation of ERTS supporting aircraft data has revealed deposits of iron formation.

Current Concepts and Ongoing Research in the Prevention and Treatment of Open Fracture Infections

PubMed Central

Hannigan, Geoffrey D.; Pulos, Nicholas; Grice, Elizabeth A.; Mehta, Samir

2015-01-01

Significance: Open fractures are fractures in which the bone has violated the skin and soft tissue. Because of their severity, open fractures are associated with complications that can result in increased lengths of hospital stays, multiple operative interventions, and even amputation. One of the factors thought to influence the extent of these complications is exposure and contamination of the open fracture with environmental microorganisms, potentially those that are pathogenic in nature. Recent Advances: Current open fracture care aims to prevent infection by wound classification, prophylactic antibiotic administration, debridement and irrigation, and stable fracture fixation. Critical Issues: Despite these established treatment paradigms, infections and infection-related complications remain a significant clinical burden. To address this, improvements need to be made in our ability to detect bacterial infections, effectively remove wound contamination, eradicate infections, and treat and prevent biofilm formation associated with fracture fixation hardware. Future Directions: Current research is addressing these critical issues. While culture methods are of limited value, culture-independent molecular techniques are being developed to provide informative detection of bacterial contamination and infection. Other advanced contamination- and infection-detecting techniques are also being investigated. New hardware-coating methods are being developed to minimize the risk of biofilm formation in wounds, and immune stimulation techniques are being developed to prevent open fracture infections. PMID:25566415

Geological Mapping of the Ac-H-9 Occator Quadrangle of Ceres from NASA Dawn Mission

NASA Astrophysics Data System (ADS)

Buczkowski, Debra; Williams, David; Scully, Jennifer; Mest, Scott; Crown, David; Aileen Yingst, R.; Schenk, Paul; Jaumann, Ralf; Roatsch, Thomas; Preusker, Frank; Platz, Thomas; Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael; Marchi, Simone; De Sanctis, M. Cristina; Raymond, Carol; Russell, Chris

2016-04-01

As was done at Vesta [1], the Dawn Science Team is conducting a geological mapping cam-paign at Ceres during the nominal mission, including iterative mapping using data obtained dur-ing each orbital phase. We are using geological mapping as a method to identify the geologic processes that have modified the surface of dwarf planet Ceres. We here present the geology of the Ac-H-9 Occator quadrangle, located between 22°S-22°N and 216-288°E. The Ac-H-9 map area is completely within the topographically high region on Ceres named Erntedank Planum. It is one of two longitudinally distinct regions where ESA Herschel space telescope data suggested a release of water vapor [2]. The quadrangle includes several other notable features, including those discussed below. Occator is the 92 km diameter crater that hosts the "Bright Spot 5" that was identified in Hubble Space Telescope data [3], which is actually comprised of multiple bright spots on the crater floor. The floor of Occator is cut by linear fractures, while circumferential fractures are found in the ejecta and on the crater walls. The bright spots are noticeably associated with the floor fractures, although the brightest spot is associated with a central pit [4]. Multiple lobate flows are observed on the crater floor; these appear to be sourced from the center of the crater. The crater has a scalloped rim that is cut by regional linear structures, displaying a cross-section of one structure in the crater wall. Color data show that the Occator ejecta have multiple colors, generally related to changes in morphology. Azacca is a 50 km diameter crater that has a central peak and bright spots on its floor and within its ejecta. Like Occator, Azacca has both floor fractures and circumferential fractures in its ejecta and crater walls. Also like Occator, the Azacca ejecta is multi-colored with variable morphology. Linear structures - including grooves, pit crater chains, fractures and troughs - cross much of the eastern hemisphere of Ceres. Some of these structures appear to be radial to the large basins Urvara and Yalode, and most likely formed due to impact processes. However, a set of regional linear structures (RLS) do not have any obvious relationship to impact craters and may represent internally driven tectonics [5]. In the Ac-H-9 map area, many of the longer RLS are comprised of smaller structures that have linked together, suggestive of en echelon fracturing. Also, many of the RLS are crosscut by the linear features radial to Urvara and Yalode, indicating they are not fractures formed due to stresses released during those impact events. Kirnis is a 115 km diameter crater with a degraded rim deformed by one of RLS pit crater chains. A dome-like feature on the floor of Kirnis might represent uplifting of the Ceres surface. References: [1] Yingst et al. (2014) PSS, 103, 2-23. [2] Küppers, M., et al. (2014) Nature, 505, 525-527. [3] Li J.Y. et al. (2006) Icarus, 182, 143-160. [4]Schenk, P. et al. (2015) EPSC2015-527. [5] Buczkowski D.L. et al. (2015) GSA, abstract #261709.

Identified EM Earthquake Precursors

NASA Astrophysics Data System (ADS)

Jones, Kenneth, II; Saxton, Patrick

2014-05-01

Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for recurrence, duration, and frequency response. At the Southern California field sites, one loop antenna was positioned for omni-directional reception and also detected a strong First Schumann Resonance; however, additional Schumann Resonances were absent. At the Timpson, TX field sites, loop antennae were positioned for directional reception, due to earthquake-induced, hydraulic fracturing activity currently conducted by the oil and gas industry. Two strong signals, one moderately strong signal, and approximately 6-8 weaker signals were detected in the immediate vicinity. The three stronger signals were mapped by a biangulation technique, followed by a triangulation technique for confirmation. This was the first antenna mapping technique ever performed for determining possible earthquake epicenters. Six and a half months later, Timpson experienced two M4 (M4.1 and M4.3) earthquakes on September 2, 2013 followed by a M2.4 earthquake three days later, all occurring at a depth of five kilometers. The Timpson earthquake activity now has a cyclical rate and a forecast was given to the proper authorities. As a result, the Southern California and Timpson, TX field results led to an improved design and construction of a third prototype antenna. With a loop antenna array, a viable communication system, and continuous monitoring, a full fracture cycle can be established and observed in real-time. In addition, field data could be reviewed quickly for assessment and lead to a much more improved earthquake forecasting capability. The EM precursors determined by this method appear to surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

Seismic determination of saturation in fractured reservoirs

USGS Publications Warehouse

Brown, R.L.; Wiggins, M.L.; Gupta, A.

2002-01-01

Detecting the saturation of a fractured reservoir using shear waves is possible when the fractures have a geometry that induces a component of movement perpendicular to the fractures. When such geometry is present, vertically traveling shear waves can be used to examine the saturation of the fractured reservoir. Tilted, corrugated, and saw-tooth fracture models are potential examples.

Detection of Natural Fractures from Observed Surface Seismic Data Based on a Linear-Slip Model

NASA Astrophysics Data System (ADS)

Chen, Huaizhen; Zhang, Guangzhi

2018-03-01

Natural fractures play an important role in migration of hydrocarbon fluids. Based on a rock physics effective model, the linear-slip model, which defines fracture parameters (fracture compliances) for quantitatively characterizing the effects of fractures on rock total compliance, we propose a method to detect natural fractures from observed seismic data via inversion for the fracture compliances. We first derive an approximate PP-wave reflection coefficient in terms of fracture compliances. Using the approximate reflection coefficient, we derive azimuthal elastic impedance as a function of fracture compliances. An inversion method to estimate fracture compliances from seismic data is presented based on a Bayesian framework and azimuthal elastic impedance, which is implemented in a two-step procedure: a least-squares inversion for azimuthal elastic impedance and an iterative inversion for fracture compliances. We apply the inversion method to synthetic and real data to verify its stability and reasonability. Synthetic tests confirm that the method can make a stable estimation of fracture compliances in the case of seismic data containing a moderate signal-to-noise ratio for Gaussian noise, and the test on real data reveals that reasonable fracture compliances are obtained using the proposed method.

Structural Maps of the V-17 Beta Regio Quadrangle, Venus

NASA Technical Reports Server (NTRS)

Basilevsky, A. t.; Head, James W.

2008-01-01

These represent slices of the geologic map into 7 time-stratigraphic levels whose descriptions are found in [3-6]. From older to younger they are: 1) Tessera material unit (t), 2) Densely fractured plains material unit (pdf), 3) Fractured and ridged plains material unit (pfr), 4) Tessera transitional terrain structural unit (tt), 5) Fracture belts structural unit (fb), 6) Shield plains (psh) and plains with wrinkle ridges (pwr) material units combined, and 7) Lobate (pl) and smooth (ps) plains material units combined and, approximately contemporaneous with them, the structural unit of rifted terrain (rt). Each slice shows the generalized pattern of structures typical of these units. Figures 1-7 show the seven maps and Figure 8 shows the combined map illustrating what is shown in the seven maps. To visualize the Beta Regio uplift outlines, the major structure of this area, we show the +0.5 km and +2.5 km contour lines, corresponding respectively to the base and the mid-height of the uplift. It is seen in Figures 1-2 and 4 the trends of t, pdf and tt occupy relatively small areas and their structures seen in these small windows appear rather variable and with almost no orientation heritage with time. Figure 3 shows that swarms of ridge belts trend mostly NW and go through the Beta structure with no alignment with it, suggesting that this structure did not yet exist at this time. Figure 5 shows that fracture belts align along the northern base of the Beta uplift suggesting onset of the formation of this structure. Figure 6 shows that wrinkle ridges do not show alignment with the Beta uplift suggesting that this already forming structure was not high enough to exert topographic stress in its vicinity. Figure 7 shows that the Beta uplift has Devana Chasma as an axial rift zone, suggesting a genetic link between the uplift and rifting. Figure 8 shows that structural trends in this area significantly changed with time.

Stakeholder Engagement Road Map and Peer Review Overview for EPA's Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources

EPA Pesticide Factsheets

This roadmap outlines EPA’s plans to build upon the Agency’s commitment to transparency & stakeholder engagement coordinated during the development of the Hydraulic Fracturing (HF) Study Plan & will help inform the 2014 HF study draft assessment report.

Method for detecting moment connection fracture using high-frequency transients in recorded accelerations

USGS Publications Warehouse

Rodgers, J.E.; Elebi, M.

2011-01-01

The 1994 Northridge earthquake caused brittle fractures in steel moment frame building connections, despite causing little visible building damage in most cases. Future strong earthquakes are likely to cause similar damage to the many un-retrofitted pre-Northridge buildings in the western US and elsewhere. Without obvious permanent building deformation, costly intrusive inspections are currently the only way to determine if major fracture damage that compromises building safety has occurred. Building instrumentation has the potential to provide engineers and owners with timely information on fracture occurrence. Structural dynamics theory predicts and scale model experiments have demonstrated that sudden, large changes in structure properties caused by moment connection fractures will cause transient dynamic response. A method is proposed for detecting the building-wide level of connection fracture damage, based on observing high-frequency, fracture-induced transient dynamic responses in strong motion accelerograms. High-frequency transients are short (<1 s), sudden-onset waveforms with frequency content above 25 Hz that are visually apparent in recorded accelerations. Strong motion data and damage information from intrusive inspections collected from 24 sparsely instrumented buildings following the 1994 Northridge earthquake are used to evaluate the proposed method. The method's overall success rate for this data set is 67%, but this rate varies significantly with damage level. The method performs reasonably well in detecting significant fracture damage and in identifying cases with no damage, but fails in cases with few fractures. Combining the method with other damage indicators and removing records with excessive noise improves the ability to detect the level of damage. ?? 2010 Elsevier B.V. All rights reserved.

Evaluation of hydrologic data collected at the North Penn Area 12 Superfund Site, Montgomery County, Pennsylvania

USGS Publications Warehouse

Senior, Lisa A.; Grazul, Kevin E.; Wood, Charles R.

1998-01-01

The North Penn Area 12 Superfund Site is underlain by the Lockatong Formation, which consists of interbedded gray to black siltstone and shale. The beds of the Lockatong Formation strike northeast and dip about 10d to 20d to the northwest in the vicinity of the site. Ground water moves through fractures that are nearly vertical and horizontal in the shale and siltstone. Permeability and storage are very low. Borehole-geophysical logs were obtained from eight wells to determine the location of fractures, water-producing and water-receiving intervals, and intervals of borehole flow. The logs also were used to quantify fluid movement in the borehole, to characterize the lithology, and to obtain data on well construction. The logs indicate fractures at depths less than 100 feet are more frequent and generally are more productive than fractures at depths greater than 100 feet. The fluid resistivity of water in shallow intervals usually was greater than that in deeper intervals. The rate and direction of fluid movement under nonpumping conditions differs in the boreholes logged. In the northwest part of the site, no vertical flow was detected in three wells and very small amounts of flow were measured in two wells. In the southwest part of the site, downward flow was measured in two wells. Aquifer-isolation tests in three wells provided information on hydraulic heads and specific capacities in discrete vertical intervals and allowed collection of water samples form discrete water-bearing intervals. Natural annual fluctuations of water levels in 11 wells ranged form 11.4 to 28.3 feet. Seven of the 11 wells gave very similar water-level hydrographs. The four southernmost wells on the site show rises in water levels after precipitation much sooner than the other seven wells. Two other wells show daily fluctuations caused by pumping. A potentiometric-surface map of the site and vicinity was prepared from water-level measurements made in late July 1995. The map can be used to determine the approximate direction of ground-water flow.

The Unconventional Revolution in Exploration Geophysics

NASA Astrophysics Data System (ADS)

House, N. J.

2014-12-01

During the last 25 years, 3D seismic imaging has revolutionized hydrocarbon exploration by delivering an accurate 3 dimensional picture of the subsurface. The image is capable of detecting fluids within the reservoir, and has significantly reduced the risk of locating and developing hydrocarbon deposits. In late 1990s, deregulation of natural gas prices allowed long recognized deposits of natural gas locked in tight rocks be economic. It sparked factory drilling (repeatable high density evenly spaced) wells and hydraulic fracturing that would help unlock the reservoirs. All that was needed was a geologist to determine depths and limits of the reservoir and engineers to drill and complete the wells. If 3D seismic data was available, it might have been used to define both the limits of the field and drilling hazards. Generally the cost and time required to process and interpret 3D Seismic was considered too high to affect the perceived geologic risk of the Factory approach. Completion costs in unconventional reservoirs account for over 50% of the well costs. It's therefore critical to understand the geometry of how the rock is fracturing and determine optimum well spacing to balance the cost of development with the value of the gas or oil being produced. By extending AVO to the pre-stack domain, it's possible to simultaneously invert for Vp, Vs and density. Armed with these three fundamental rock properties that dictate elastic and inelastic rock response, researchers were able to combine those properties to tie directly to how well a rock will respond to hydraulic fracturing, or which rocks contain a higher TOC, or other rock properties that control how a rock responds to seismic waves or hydraulic fracturing. Combining these results allows interpreters to map areas of higher productivity, and identify bypassed reserves. Currently hundreds of different seismic attributes that are generated from 3D seismic data are used to identify the highest productive areas and how to develop them. MicroSeismic mapping has made completion more efficient and safe. While the geophysics involved in unconventional resource development may not be the first thought in the board room, thier data has become an accepted early development tool of successful oil and gas companies.

The role of carboxy-terminal cross-linking telopeptide of type I collagen, dual x-ray absorptiometry bone strain and Romberg test in a new osteoporotic fracture risk evaluation: A proposal from an observational study.

PubMed

Ulivieri, Fabio M; Piodi, Luca P; Grossi, Enzo; Rinaudo, Luca; Messina, Carmelo; Tassi, Anna P; Filopanti, Marcello; Tirelli, Anna; Sardanelli, Francesco

2018-01-01

The consolidated way of diagnosing and treating osteoporosis in order to prevent fragility fractures has recently been questioned by some papers, which complained of overdiagnosis and consequent overtreatment of this pathology with underestimating other causes of the fragility fractures, like falls. A new clinical approach is proposed for identifying the subgroup of patients prone to fragility fractures. This retrospective observational study was conducted from January to June 2015 at the Nuclear Medicine-Bone Metabolic Unit of the of the Fondazione IRCCS Ca' Granda, Milan, Italy. An Italian population of 125 consecutive postmenopausal women was investigated for bone quantity and bone quality. Patients with neurological diseases regarding balance and vestibular dysfunction, sarcopenia, past or current history of diseases and use of drugs known to affect bone metabolism were excluded. Dual X-ray absorptiometry was used to assess bone quantity (bone mineral density) and bone quality (trabecular bone score and bone strain). Biochemical markers of bone turnover (type I collagen carboxy-terminal telopeptide, alkaline phosphatase, vitamin D) have been measured. Morphometric fractures have been searched by spine radiography. Balance was evaluated by the Romberg test. The data were evaluated with the neural network analysis using the Auto Contractive Map algorithm. The resulting semantic map shows the Minimal Spanning Tree and the Maximally Regular Graph of the interrelations between bone status parameters, balance conditions and fractures of the studied population. A low fracture risk seems to be related to a low carboxy-terminal cross-linking telopeptide of type I collagen level, whereas a positive Romberg test, together with compromised bone trabecular microarchitecture DXA parameters, appears to be strictly connected with fragility fractures. A simple assessment of the risk of fragility fracture is proposed in order to identify those frail patients at risk for osteoporotic fractures, who may have the best benefit from a pharmacological and physiotherapeutic approach.

Goal-directed ultrasound in the detection of long-bone fractures

NASA Technical Reports Server (NTRS)

Marshburn, Thomas H.; Legome, Eric; Sargsyan, Ashot; Li, Shannon Melton James; Noble, Vicki A.; Dulchavsky, Scott A.; Sims, Carrie; Robinson, David

2004-01-01

BACKGROUND: New portable ultrasound (US) systems are capable of detecting fractures in the remote setting. However, the accuracy of ultrasound by physicians with minimal ultrasound training is unknown. METHODS: After one hour of standardized training, physicians with minimal US experience clinically evaluated patients presenting with pain and trauma to the upper arm or leg. The investigators then performed a long-bone US evaluation, recording their impression of fracture presence or absence. Results of the examination were compared with routine plain or computer aided radiography (CT). RESULTS: 58 patients were examined. The sensitivity and specificity of US were 92.9% and 83.3%, and of the physical examination were 78.6% and 90.0%, respectively. US provided improved sensitivity with less specificity compared with physical examination in the detection of fractures in long bones. CONCLUSION: Ultrasound scans by minimally trained clinicians may be used to rule out a long-bone fracture in patients with a medium to low probability of fracture.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLing, Travis; Carpenter, Michael; Brandon, William

The Environmental Protection Agency (EPA) has teamed with Battelle Energy Alliance, LLC (BEA) at Idaho National Laboratory (INL) to facilitate further testing of geologic-fracture-identification methodology at a field site near the Monsanto Superfund Site located in Soda Springs, Idaho. INL has the necessary testing and technological expertise to perform this work. Battelle Memorial Institute (BMI) has engaged INL to perform this work through a Work for Others (WFO) Agreement. This study continues a multi-year collaborative effort between INL and EPA to test the efficacy of using field deployed Cr-39 radon in soil portals. This research enables identification of active fracturesmore » capable of transporting contaminants at sites where fractures are suspected pathways into the subsurface. Current state of the art methods for mapping fracture networks are exceedingly expensive and notoriously inaccurate. The proposed WFO will evaluate the applicability of using cheap, readily available, passive radon detectors to identify conductive geologic structures (i.e. fractures, and fracture networks) in the subsurface that control the transport of contaminants at fracture-dominated sites. The proposed WFO utilizes proven off-the-shelf technology in the form of CR-39 radon detectors, which have been widely deployed to detect radon levels in homes and businesses. In an existing collaborative EPA/INL study outside of this workscope,. CR-39 detectors are being utilized to determine the location of active transport fractures in a fractured granitic upland adjacent to a landfill site at the Fort Devens, MA that EPA-designated as National Priorities List (NPL) site. The innovative concept of using an easily deployed port that allows the CR-39 to measure the Rn-222 in the soil or alluvium above the fractured rock, while restricting atmospheric Rn-222 and soil sourced Ra from contaminating the detector is unique to INL and EPA approach previously developed. By deploying a series of these inexpensive detector-casing combinations statistical samples of the Rn-222 flux can be measured, elucidating the most communicative fractures (i.e. fractures that are actively transporting water and gasses). The Rn-222 measurements can then be used as an input to create a more accurate conceptual model to be used for transport modeling and related cleanup activities. If the team’s approach is demonstrated to be applicable to a wide variety of rock types and soil conditions it might potentially offer significant cost saving without a reduction in data quality at Monsanto Superfund and other sites underlain by fracture-dominated bedrock.« less

City of Flagstaff Project: Ground Water Resource Evaluation, Remote Sensing Component

USGS Publications Warehouse

Chavez, Pat S.; Velasco, Miguel G.; Bowell, Jo-Ann; Sides, Stuart C.; Gonzalez, Rosendo R.; Soltesz, Deborah L.

1996-01-01

Many regions, cities, and towns in the Western United States need new or expanded water resources because of both population growth and increased development. Any tools or data that can help in the evaluation of an area's potential water resources must be considered for this increasingly critical need. Remotely sensed satellite images and subsequent digital image processing have been under-utilized in ground water resource evaluation and exploration. Satellite images can be helpful in detecting and mapping an area's regional structural patterns, including major fracture and fault systems, two important geologic settings for an area's surface to ground water relations. Within the United States Geological Survey's (USGS) Flagstaff Field Center, expertise and capabilities in remote sensing and digital image processing have been developed over the past 25 years through various programs. For the City of Flagstaff project, this expertise and these capabilities were combined with traditional geologic field mapping to help evaluate ground water resources in the Flagstaff area. Various enhancement and manipulation procedures were applied to the digital satellite images; the results, in both digital and hardcopy format, were used for field mapping and analyzing the regional structure. Relative to surface sampling, remotely sensed satellite and airborne images have improved spatial coverage that can help study, map, and monitor the earth surface at local and/or regional scales. Advantages offered by remotely sensed satellite image data include: 1. a synoptic/regional view compared to both aerial photographs and ground sampling, 2. cost effectiveness, 3. high spatial resolution and coverage compared to ground sampling, and 4. relatively high temporal coverage on a long term basis. Remotely sensed images contain both spectral and spatial information. The spectral information provides various properties and characteristics about the surface cover at a given location or pixel (that is, vegetation and/or soil type). The spatial information gives the distribution, variation, and topographic relief of the cover types from pixel to pixel. Therefore, the main characteristics that determine a pixel's brightness/reflectance and, consequently, the digital number (DN) assigned to the pixel, are the physical properties of the surface and near surface, the cover type, and the topographic slope. In this application, the ability to detect and map lineaments, especially those related to fractures and faults, is critical. Therefore, the extraction of spatial information from the digital images was of prime interest in this project. The spatial information varies among the different spectral bands available; in particular, a near infrared spectral band is better than a visible band when extracting spatial information in highly vegetated areas. In this study, both visible and near infrared bands were analyzed and used to extract the desired spatial information from the images. The wide swath coverage of remotely sensed satellite digital images makes them ideal for regional analysis and mapping. Since locating and mapping highly fractured and faulted areas is a major requirement for ground water resource evaluation and exploration this aspect of satellite images was considered critical; it allowed us to stand back (actually up about 440 miles), look at, and map the regional structural setting of the area. The main focus of the remote sensing and digital image processing component of this project was to use both remotely sensed digital satellite images and a Digital Elevation Model (DEM) to extract spatial information related to the structural and topographic patterns in the area. The data types used were digital satellite images collected by the United States' Landsat Thematic Mapper (TM) and French Systeme Probatoire d'Observation de laTerre (SPOT) imaging systems, along with a DEM of the Flagstaff region. The USGS Mini Image Processing Sy

Bone scanning in the detection of occult fractures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batillas, J.; Vasilas, A.; Pizzi, W.F.

1981-07-01

The potential role of bone scanning in the early detection of occult fractures following acute trauma was investigated. Technetium 99m pyrophosphate bone scans were obtained in patients with major clinical findings and negative or equivocal roentgenograms following trauma. Bone scanning facilitated the prompt diagnosis of occult fractures in the hip, knee, wrist, ribs and costochondral junctions, sternum, vertebrae, sacrum, and coccyx. Several illustrative cases are presented. Roentgenographic confirmation occurred following a delay of days to weeks and, in some instances, the roentgenographic findings were subtle and could be easily overlooked. This study demonstrates bone scanning to be invaluable and definitivemore » in the prompt detection of occult fractures.« less

76 FR 1996 - Airworthiness Directives; M7 Aerospace LP (Type Certificate Previously Held by Fairchild Aircraft...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-12

... manufacturer of inner glass ply fracture. We are issuing this AD to detect and correct damage to the cockpit...: Discussion We received reports from the windshield manufacturer of inner glass ply fractures found on 19... reports from the windshield manufacturer of inner glass ply fracture. We are issuing this AD to detect and...

[Detection of tibial condylar fractures using 3D imaging with a mobile image amplifier (Siemens ISO-C-3D): Comparison with plain films and spiral CT].

PubMed

Kotsianos, D; Rock, C; Wirth, S; Linsenmaier, U; Brandl, R; Fischer, T; Euler, E; Mutschler, W; Pfeifer, K J; Reiser, M

2002-01-01

To analyze a prototype mobile C-arm 3D image amplifier in the detection and classification of experimental tibial condylar fractures with multiplanar reconstructions (MPR). Human knee specimens (n = 22) with tibial condylar fractures were examined with a prototype C-arm (ISO-C-3D, Siemens AG), plain films (CR) and spiral CT (CT). The motorized C-arm provides fluoroscopic images during a 190 degrees orbital rotation computing a 119 mm data cube. From these 3D data sets MP reconstructions were obtained. All images were evaluated by four independent readers for the detection and assessment of fracture lines. All fractures were classified according to the Müller AO classification. To confirm the results, the specimens were finally surgically dissected. 97 % of the tibial condylar fractures were easily seen and correctly classified according to the Müller AO classification on MP reconstruction of the ISO-C-3D. There is no significant difference between ISO-C and CT in detection and correct classification of fractures, but ISO-CD-3D is significant by better than CR. The evaluation of fractures with the ISO-C is better than with plain films alone and comparable to CT scans. The three-dimensional reconstruction of the ISO-C can provide important information which cannot be obtained from plain films. The ISO-C-3D may be useful in planning operative reconstructions and evaluating surgical results in orthopaedic surgery of the limbs.

Bone images from dual-energy subtraction chest radiography in the detection of rib fractures.

PubMed

Szucs-Farkas, Zsolt; Lautenschlager, Katrin; Flach, Patricia M; Ott, Daniel; Strautz, Tamara; Vock, Peter; Ruder, Thomas D

2011-08-01

To assess the sensitivity and image quality of chest radiography (CXR) with or without dual-energy subtracted (ES) bone images in the detection of rib fractures. In this retrospective study, 39 patients with 204 rib fractures and 24 subjects with no fractures were examined with a single exposure dual-energy subtraction digital radiography system. Three blinded readers first evaluated the non-subtracted posteroanterior and lateral chest radiographs alone, and 3 months later they evaluated the non-subtracted images together with the subtracted posteroanterior bone images. The locations of rib fractures were registered with confidence levels on a 3-grade scale. Image quality was rated on a 5-point scale. Marks by readers were compared with fracture localizations in CT as a standard of reference. The sensivity for fracture detection using both methods was very similar (34.3% with standard CXR and 33.5% with ES-CXR, p=0.92). At the patient level, both sensitivity (71.8%) and specificity (92.9%) with or without ES were identical. Diagnostic confidence was not significantly different (2.61 with CXR and 2.75 with ES-CXR, p=0.063). Image quality with ES was rated higher than that on standard CXR (4.08 vs. 3.74, p<0.001). Despite a better image quality, adding ES bone images to standard radiographs of the chest does not provide better sensitivity or improved diagnostic confidence in the detection of rib fractures. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

[Arthroscopy-guided fracture management. Ankle joint and calcaneus].

PubMed

Schoepp, C; Rixen, D

2013-04-01

Arthroscopic fracture management of the ankle and calcaneus requires a differentiated approach. The aim is to minimize surgical soft tissue damage and to visualize anatomical fracture reduction arthroscopically. Moreover, additional cartilage damage can be detected and treated. The arthroscopic approach is limited by deep impressions of the joint surface needing cancellous bone grafting, by multiple fracture lines on the articular side and by high-grade soft tissue damage. An alternative to the minimally invasive arthroscopic approach is open arthroscopic reduction in conventional osteosynthesis. This facilitates correct assessment of surgical reduction of complex calcaneal fractures, otherwise remaining non-anatomical reduction might not be fluoroscopically detected during surgery.

Borehole geophysical investigation of a formerly used defense site, Machiasport, Maine, 2003-2006

USGS Publications Warehouse

Johnson, Carole D.; Mondazzi, Remo A.; Joesten, Peter K.

2011-01-01

The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, collected borehole geophysical logs in 18 boreholes and interpreted the data along with logs from 19 additional boreholes as part of an ongoing, collaborative investigation at three environmental restoration sites in Machiasport, Maine. These sites, located on hilltops overlooking the seacoast, formerly were used for military defense. At each of the sites, chlorinated solvents, used as part of defense-site operations, have contaminated the fractured-rock aquifer. Borehole geophysical techniques and hydraulic methods were used to characterize bedrock lithology, fractures, and hydraulic properties. In addition, each geophysical method was evaluated for effectiveness for site characterization and for potential application for further aquifer characterization and (or) evaluation of remediation efforts. Results of borehole geophysical logging indicate the subsurface is highly fractured, metavolcanic, intrusive, metasedimentary bedrock. Selected geophysical logs were cross-plotted to assess correlations between rock properties. These plots included combinations of gamma, acoustic reflectivity, electromagnetic induction conductivity, normal resistivity, and single-point resistance. The combined use of acoustic televiewer (ATV) imaging and natural gamma logs proved to be effective for delineating rock types. Each of the rock units in the study area could be mapped in the boreholes, on the basis of the gamma and ATV reflectivity signatures. The gamma and mean ATV reflectivity data were used along with the other geophysical logs for an integrated interpretation, yielding a determination of quartz monzonite, rhyolite, metasedimentary units, or diabase/gabbro rock types. The interpretation of rock types on the basis of the geophysical logs compared well to drilling logs and geologic mapping. These results may be helpful for refining the geologic framework at depth. A stereoplot of all fractures intersecting the boreholes indicates numerous fractures, a high proportion of steeply dipping fractures, and considerable variation in fracture orientation. Low-dip-angle fractures associated with unloading and exfoliation are also present, especially at a depth of less than 100 feet below the top of casing. These sub-horizontal fractures help to connect the steeply dipping fractures, making this a highly connected fracture network. The high variability in the fracture orientations also increases the connectivity of the fracture network. A preliminary comparison of all fracture data from all the boreholes suggests fracturing decreases with depth. Because all the boreholes were not drilled to the same depth, however, there is a clear sampling bias. Hence, the deepest boreholes are analyzed separately for fracture density. For the deepest boreholes in the study, the intensity of fracturing does not decline significantly with depth. It is possible the fractures observed in these boreholes become progressively tighter or closed with depth, but this is difficult to verify with the borehole methods used in this investigation. The fact that there are more sealed fractures at depth (observed in optical televiewer logs in some of the boreholes) may indicate less opening of the sealed fractures, less water moving through the rock, and less weathering of the fracture infilling minerals. Although the fracture orientation remained fairly constant with depth, differences in the fracture patterns for the three restoration sites indicate the orientation of fractures varies across the study area. The fractures in boreholes on Miller Mountain predominantly strike northwest-southeast, and to a lesser degree they strike northeast. The fractures on or near the summit of Howard Mountain strike predominantly east-west and dip north and south, and the fractures near the Transmitter Site strike northeast-southwest and dip northwest and southeast. The fracture populations for the boreholes on or near the summit of Howard Mountain show more variation than at the other two sites. This variation may be related to the proximity of the fault, which is northeast of the summit of Howard Mountain. In a side-by-side comparison of stereoplots from selected boreholes, there was no clear correspondence between fracture orientation and proximity to the fault. There is, however, a difference in the total populations of fractures for the boreholes on or near the summit of Howard Mountain and the boreholes near the Transmitter Site. Further to the southwest and further away from the fault, the fractures at the Transmitter Site predominantly strike northeast-southwest and northwest-southeast.Heat-pulse flowmeter (HPFM) logging was used to identify transmissive fractures and to estimate the hydraulic properties along the boreholes. Ambient downflow was measured in 13 boreholes and ambient upflow was measured in 9 boreholes. In nine other bedrock boreholes, the HPFM did not detect measurable vertical flow. The observed direction of vertical flow in the boreholes generally was consistent with the conceptual flow model of downward movement in recharge locations and upward flow in discharge locations or at breaks in the slope of land surface. Under low-rate pumping or injection rates [0.25 to 1 gallon per minute (gal/min)], one to three inflow zones were identified in each borehole. Two limitations of HPFM methods are (1) the HPFM can only identify zones within 1.5 to 2 orders of magnitude of the most transmissive zone in each borehole, and (2) the HPFM cannot detect flow rates less than 0.010 + or - 0.005 gal/min, which corresponds to a transmissivity of about 1 foot squared per day (ft2/d). Consequently, the HPFM is considered an effective tool for identifying the most transmissive fractures in a borehole, down to its detection level. Transmissivities below that cut-off must be measured with another method, such as packer testing or fluid-replacement logging. Where sufficient water-level and flowmeter data were available, HPFM results were numerically modeled. For each borehole model, the fracture location and measured flow rates were specified, and the head and transmissivity of each fracture zone were adjusted until a model fit was achieved with the interpreted ambient and stressed flow profiles. The transmissivities calculated by this method are similar to the results of an open-hole slug test; with the added information from the flowmeter, however, the head and transmissivity of discrete zones also can be determined. The discrete-interval transmissivities ranged from 0.16 to 330 ft2/d. The flowmeter-derived open-hole transmissivity, which is the combined total of each of the transmissive zones, ranged from 1 to 511 ft2/d. The whole-well open-hole transmissivity values determined with HPFM methods were compared to the results of open-hole hydraulic tests. Despite the fact that the flowmeter-derived transmissivities consistently were lower than the estimates derived from open-hole hydraulic tests alone, the correlation was very strong (with a coefficient of determination, R2, of 0.9866), indicating the HPFM method provides a reasonable estimate of transmissivities for the most transmissive fractures in the borehole. Geologic framework, fracture characterization, and estimates of hydraulic properties were interpreted together to characterize the fracture network. The data and interpretation presented in this report should provide information useful for site investigators as the conceptual site groundwater flow model is refined. Collectively, the results and the conceptual site model are important for evaluating remediation options and planning or implementing the design of a well field and borehole completions that will be adequate for monitoring flow, remediation efforts, groundwater levels, and (or) water quality. Similar kinds of borehole geophysical logging (specifically the borehole imaging, gamma, fluid logs, and HPFM) should be conducted in any newly installed boreholes and integrated with interpretations of any nearby boreholes. If boreholes are installed close to existing or other new boreholes, cross-hole flowmeter surveys may be appropriate and may help characterize the aquifer properties and connections between the boreholes.

Psychotropics and weak opioid analgesics in plasma samples of older hip fracture patients - detection frequencies and consistency with drug records.

PubMed

Waade, Ragnhild Birkeland; Molden, Espen; Martinsen, Mette Irene; Hermann, Monica; Ranhoff, Anette Hylen

2017-07-01

To determine use of psychotropic drugs and weak opioids in hip fracture patients by analysing plasma samples at admission, and compare detected drug frequencies with prescription registry data and drug records. Plasma from 250 hip fracture patients aged ≥65 years sampled at hospital admission were analysed by ultra-performance liquid chromatography-tandem mass spectrometry methods for detection of psychotropic drugs and weak opioid analgesics (alcohol also determined). Odds ratios for drugs detected in plasma of hip fracture patients vs. prescription frequencies of the same drugs in an age-, time- and region-matched reference population were calculated. Moreover, recorded and measured drugs were compared. Psychotropic drugs and/or weak opioid analgesics were detected in 158 (63%) of the patients (median age 84 years; 76% females), while alcohol was found in 19 patients (7.6%). The occurrence of diazepam (odds ratio 1.6; 95% confidence interval 1.1-2.4), nitrazepam (2.3; 1.3-4.1), selective serotonin reuptake inhibitors (1.9; 1.3-2.9) and mirtazapine (2.3; 1.2-4.3) was significantly higher in plasma samples of hip fracture patients than in prescription data from the reference population. Poor consistency between recorded and measured drugs was disclosed for z-hypnotics and benzodiazepines; e.g. diazepam was detected in 29 (11.6%), but only recorded in six (2.4%) of the patients. Plasma analysis shows that use of antidepressants and benzodiazepines in hip fracture patients is significantly more frequent than respective prescription frequencies in the general elderly population. Moreover, consistency between recorded and actual use of psychotropic fall-risk drugs is poor at hospital admission of hip fracture patients. © 2017 The British Pharmacological Society.

[Is ultrasound equal to X-ray in pediatric fracture diagnosis?].

PubMed

Moritz, J D; Hoffmann, B; Meuser, S H; Sehr, D H; Caliebe, A; Heller, M

2010-08-01

Ultrasound is currently not established for the diagnosis of fractures. The aim of this study was to compare ultrasound and X-ray beyond their use solely for the identification of fractures, i. e., for the detection of fracture type and dislocation for pediatric fracture diagnosis. Limb bones of dead young pigs served as a model for pediatric bones. The fractured bones were examined with ultrasound, X-ray, and CT, which served as the gold standard. 162 of 248 bones were fractured. 130 fractures were identified using ultrasound, and 148 using X-ray. There were some advantages of X-ray over ultrasound in the detection of fracture type (80 correct results using X-ray, 66 correct results using ultrasound). Ultrasound, however, was superior to X-ray for dislocation identification (41 correct results using X-ray, 51 correct results using ultrasound). Both findings were not statistically significant after adjustment for multiple testing. Ultrasound not only has comparable sensitivity to that of X-ray for the identification of limb fractures but is also equally effective for the diagnosis of fracture type and dislocation. Thus, ultrasound can be used as an adequate alternative method to X-ray for pediatric fracture diagnosis. Georg Thieme Verlag KG Stuttgart, New York.

Geochemical, isotopic, and dissolved gas characteristics of groundwater in a fractured crystalline-rock aquifer, Savage Municipal Well Superfund site, Milford, New Hampshire, 2011

USGS Publications Warehouse

Harte, Philip T.

2013-01-01

Tetrachloroethylene (PCE), a volatile organic compound, was detected in groundwater from deep (more than (>) 300 feet (ft) below land surface) fractures in monitoring wells tapping a crystalline-rock aquifer beneath operable unit 1 (OU1) of the Savage Municipal Well Superfund site (Weston, Inc., 2010). Operable units define remedial areas of contaminant concern. PCE contamination within the fractured-rock aquifer has been designated as a separate operable unit, operable unit 3 (OU3; Weston, Inc., 2010). PCE contamination was previously detected in the overlying glacial sand and gravel deposits and basal till, hereafter termed the Milford-Souhegan glacial-drift (MSGD) aquifer (Harte, 2004, 2006). Operable units 1 and 2 encompass areas within the MSGD aquifer, whereas the extent of the underlying OU3 has yet to be defined. The primary original source of contamination has been identified as a former manufacturing facility—the OK Tool manufacturing facility; hence OU1 sometimes has been referred to as the OK Tool Source Area (New Hampshire Department of Environmental Services, undated). A residential neighborhood of 30 to 40 houses is located in close proximity (one-quarter of a mile) from the PCE-contaminated monitoring wells. Each house has its own water-supply well installed in similar rocks as those of the monitoring wells, as indicated by the New Hampshire State geologic map (Lyons and others, 1997). An investigation was initiated in 2010 by the U.S. Environmental Protection Agency (USEPA) region 1, and the New Hampshire Department of Environmental Services (NHDES) to assess the potential for PCE transport from known contaminant locations (monitoring wells) to the residential wells. The U.S. Geological Survey (USGS) and the NHDES entered into a cooperative agreement in 2011 to assist in the evaluation of PCE transport in the fractured-rock aquifer. Periodic sampling over the last decade by the USEPA and NHDES has yet to detect PCE in groundwater from the residential-supply wells (as of 2012). However, part of assessing the potential for PCE transport involves understanding the origin of the groundwater in the monitoring and residential wells. One of the tools in delineating the movement of groundwater to wells, particularly in complex, highly heterogeneous fractured-rock aquifers, is the understanding of the geochemical and isotopic composition of groundwater (Lipfert and Reeve, 2004; Harte and others, 2012). This report summarizes findings from analyses of geochemical, isotopic, and dissolved gas characteristics of groundwater. Samples of groundwater were collected in 2011 from monitoring wells and nearby residential-supply wells in proximity to OU1.

Comparison of Ultrasonography and Radiography in Detection of Thoracic Bone Fractures; a Systematic Review and Meta-Analysis

PubMed Central

Yousefifard, Mahmoud; Baikpour, Masoud; Ghelichkhani, Parisa; Asady, Hadi; Darafarin, Abolfazl; Amini Esfahani, Mohammad Reza; Hosseini, Mostafa; Yaseri, Mehdi; Safari, Saeed

2016-01-01

Introduction: The potential benefit of ultrasonography for detection of thoracic bone fractures has been proven in various surveys but no comprehensive conclusion has been drawn yet; therefore, the present study aimed to conduct a thorough meta-analytic systematic review on this subject. Methods: Two reviewers independently carried out a comprehensive systematic search in Medline, EMBASE, ISI Web of Knowledge, Scopus, Cochrane Library, and ProQuest databases. Data were summarized as true positive, false positive, true negative and false negative and were analyzed via STATA 11.0 software using a mixed-effects binary regression model. Sources of heterogeneity were further assessed through subgroup analysis. Results: Data on 1667 patients (807 subjects with and 860 cases without thoracic fractures), whose age ranged from 0 to 92 years, were extracted from 17 surveys. Pooled sensitivity and specificity of ultrasonography in detection of thoracic bone fractures were 0.97 (95% CI: 0.90-0.99; I2= 88.88, p<0.001) and 0.94 (95% CI: 0.86-0.97; I2= 71.97, p<0.001), respectively. The same measures for chest radiography were found to be 0.77 (95% CI: 0.56-0.90; I2= 97.76, p<0.001) and 1.0 (95% CI: 0.91-1.00; I2= 97.24, p<0.001), respectively. The sensitivity of ultrasonography was higher in detection of rib fractures, compared to fractures of sternum or clavicle (97% vs. 91%). Moreover, the sensitivity was found to be higher when the procedure was carried out by a radiologist in comparison to an emergency medicine specialist (96% vs. 90%). Conclusion: Base on the findings of the present meta-analysis, screening performance characteristic of ultrasonography in detection of thoracic bone fractures was found to be higher than radiography. However, these characteristics were more prominent in detection of rib fractures and in cases where was performed by a radiologist. PMID:27274514

Comparison of Ultrasonography and Radiography in Detection of Thoracic Bone Fractures; a Systematic Review and Meta-Analysis.

PubMed

Yousefifard, Mahmoud; Baikpour, Masoud; Ghelichkhani, Parisa; Asady, Hadi; Darafarin, Abolfazl; Amini Esfahani, Mohammad Reza; Hosseini, Mostafa; Yaseri, Mehdi; Safari, Saeed

2016-01-01

The potential benefit of ultrasonography for detection of thoracic bone fractures has been proven in various surveys but no comprehensive conclusion has been drawn yet; therefore, the present study aimed to conduct a thorough meta-analytic systematic review on this subject. Two reviewers independently carried out a comprehensive systematic search in Medline, EMBASE, ISI Web of Knowledge, Scopus, Cochrane Library, and ProQuest databases. Data were summarized as true positive, false positive, true negative and false negative and were analyzed via STATA 11.0 software using a mixed-effects binary regression model. Sources of heterogeneity were further assessed through subgroup analysis. Data on 1667 patients (807 subjects with and 860 cases without thoracic fractures), whose age ranged from 0 to 92 years, were extracted from 17 surveys. Pooled sensitivity and specificity of ultrasonography in detection of thoracic bone fractures were 0.97 (95% CI: 0.90-0.99; I2= 88.88, p<0.001) and 0.94 (95% CI: 0.86-0.97; I2= 71.97, p<0.001), respectively. The same measures for chest radiography were found to be 0.77 (95% CI: 0.56-0.90; I2= 97.76, p<0.001) and 1.0 (95% CI: 0.91-1.00; I2= 97.24, p<0.001), respectively. The sensitivity of ultrasonography was higher in detection of rib fractures, compared to fractures of sternum or clavicle (97% vs. 91%). Moreover, the sensitivity was found to be higher when the procedure was carried out by a radiologist in comparison to an emergency medicine specialist (96% vs. 90%). Base on the findings of the present meta-analysis, screening performance characteristic of ultrasonography in detection of thoracic bone fractures was found to be higher than radiography. However, these characteristics were more prominent in detection of rib fractures and in cases where was performed by a radiologist.

Structural pattern of the Saïss basin and Tabular Middle Atlas in northern Morocco: Hydrological implications

NASA Astrophysics Data System (ADS)

Dauteuil, O.; Moreau, F.; Qarqori, K.

2016-07-01

The plain of Saïss is a fertile area of great agricultural production with major economic interests. Therefore, the improved knowledge about the water supply is imperative within a context of recurrent droughts and overexploitation of the groundwater. This plain is located in the Meknes-Fes basin and between two deformed domains: the Rif and Middle Atlas. The aquifers are fed by water coming from the Tabular Middle Atlas, for which the pathways are poorly constrained. This study provides new data to determine the water pathways based on a structural map produced from a novel analysis of SPOT images and a digital elevation model. This structural map reveals two fracture sets trending NE-SW and NW-SE. The first set is well known and corresponds to a main trend that controlled the tectonic and stratigraphic evolution of the study area. On the other hand, the NW-SE set was poorly described until now: it is both diffuse and widespread on the Tabular Middle Atlas. A comparison between the regional water flow trend, drainage pattern and structural map shows that the NW-SE fractures control the water flow from the Tabular Middle Atlas to the Saïss plain. A hydrological model is discussed where the water flow is confined onto Liassic carbonates and driven by NW-SE fractures. This study explains how a detailed structural mapping shows hydrology constraints.

SPECT/CT imaging in general orthopedic practice.

PubMed

Scharf, Stephen

2009-09-01

The availability of hybrid devices that combine the latest single-photon emission computed tomography (SPECT) imaging technology with multislice computed tomography (CT) scanning has allowed us to detect subtle, nonspecific abnormalities on bone scans and interpret them as specific focal areas of pathology. Abnormalities in the spine can be separated into those caused by pars fractures, facet joint arthritis, or osteophyte formation on vertebral bodies. Compression fractures can be distinguished from severe degenerative disease, both of which can cause intense activity across the spine on either planar or SPECT imaging. Localizing activity in patients who have had spinal fusion can provide tremendous insight into the causes of therapeutic failures. Infections of the spine now can be diagnosed with gallium SPECT/CT, despite the fact that gallium has long been abandoned because of its failure to detect spine infection on either planar or SPECT imaging. Small focal abnormalities in the feet and ankles can be localized well enough to make specific orthopedic diagnoses on the basis of their location. Moreover, when radiographic imaging provides equivocal or inadequate information, SPECT/CT can provide a road map for further diagnostic studies and has been invaluable in planning surgery. Our ability to localize activity within a bone or at an articular surface has allowed us to distinguish between fractures and joint disease. Increased activity associated with congenital anomalies, such as tarsal coalition and Bertolotti's syndrome have allowed us to understand the pathophysiology of these conditions, to confirm them as the cause of the patient's symptoms, and to provide information that is useful in determining appropriate clinical management. As our experience broadens, SPECT/CT will undoubtedly become an important tool in the evaluation and management of a wider variety of orthopedic patients.

Significance of clinical examination, CT and MRI scan in the diagnosis of posterior pelvic ring fractures.

PubMed

Nüchtern, J V; Hartel, M J; Henes, F O; Groth, M; Jauch, S Y; Haegele, J; Briem, D; Hoffmann, M; Lehmann, W; Rueger, J M; Großterlinden, L G

2015-02-01

Patients with a fracture in the anterior pelvic ring often simultaneously demonstrate pain in the posterior pelvic ring. The aim of the present prospective study was to assess the sensitivity of CT, MRI and clinical examination in the detection of fractures in the posterior pelvic ring in patients with fractures of the anterior pelvic ring diagnosed in conventional radiographs. Sixty patients with radiographic signs of an anterior pelvic ring injury were included in this prospective analysis. Following a focused clinical examination of the posterior pelvis, all patients underwent both a CT and then a MRI scan of their pelvis. Two board certified radiologists evaluated the CT and MRI scans independently. To estimate the presence of osteoporosis the Hounsfield units of the vertebral body of L5 were measured in each case. Fifty-three women and seven men, with a mean age of 74.7+/-15.6 years were included into the study. A fracture of the posterior pelvic ring was found in fourty-eight patients (80%) patients using MRI. Fractures of the posterior pelvic ring would have been missed in eight cases (17%), if only CT had been used. Eighty-five percent of the patients with a posterior fracture had an osteoporosis. The majority of the cases suffered from a low energy trauma. Thirty-eight patients (83%) with positive clinical signs at the posterior pelvic ring actually had a fracture of the posterior pelvic ring in the MRI. The clinical examination proved to be equally effective to CT in detecting posterior pelvic ring fractures. The significance of both, clinical examination and CT was confirmed in the detection of fractures in the posterior pelvic ring. MRI examination of the pelvis however, was found to be superior in detecting undislocated fractures in a cohort of patients with a high incidence of osteoporosis. Using MRI may be beneficial in select cases, especially when reduced bone density is suspected. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterization of sintered SiC by using NDE

NASA Technical Reports Server (NTRS)

Baaklini, George Y.

1988-01-01

Capabilities of projection microfocus X-radiography and of ultrasonic velocity and attenuation for characterizing silicon carbide specimens were assessed. Silicon carbide batches covered a range of densities and different microstructural characteristics. Room-temperature, four-point flexural strength tests were conducted. Fractography was used to identify types, sizes, and locations of fracture origins. Fracture toughness values were calculated from fracture strength and flaw characterization data. Detection capabilities of radiography for fracture-causing flaws were evaluated. Applicability of ultrasonics for verifying material strength and toughness was examined. Radiography proved useful in detecting high-density inclusions and isolated voids, but failed in detecting surface and subsurface agglomerates and large grains as fracture origins. Ultrasonic velocity dependency on density was evident. Attenuation dependency on density and mean pore size was clearly demonstrated. Understanding attenuation as a function of toughness was limited by shortcomings in K sub IC determination.

Geophysical logging and geologic mapping data in the vicinity of the GMH Electronics Superfund site near Roxboro, North Carolina

USGS Publications Warehouse

Chapman, Melinda J.; Clark, Timothy W.; Williams, John H.

2013-01-01

Geologic mapping, the collection of borehole geophysical logs and images, and passive diffusion bag sampling were conducted by the U.S. Geological Survey North Carolina Water Science Center in the vicinity of the GMH Electronics Superfund site near Roxboro, North Carolina, during March through October 2011. The study purpose was to assist the U.S. Environmental Protection Agency in the development of a conceptual groundwater model for the assessment of current contaminant distribution and future migration of contaminants. Data compilation efforts included geologic mapping of more than 250 features, including rock type and secondary joints, delineation of more than 1,300 subsurface features (primarily fracture orientations) in 15 open borehole wells, and the collection of passive diffusion-bag samples from 42 fracture zones at various depths in the 15 wells.

Detecting Gear Tooth Fatigue Cracks in Advance of Complete Fracture

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.; Lewicki, David G.

1996-01-01

Results of using vibration-based methods to detect gear tooth fatigue cracks are presented. An experimental test rig was used to fail a number of spur gear specimens through bending fatigue. The gear tooth fatigue crack in each test was initiated through a small notch in the fillet area of a tooth on the gear. The primary purpose of these tests was to verify analytical predictions of fatigue crack propagation direction and rate as a function of gear rim thickness. The vibration signal from a total of three tests was monitored and recorded for gear fault detection research. The damage consisted of complete rim fracture on the two thin rim gears and single tooth fracture on the standard full rim test gear. Vibration-based fault detection methods were applied to the vibration signal both on-line and after the tests were completed. The objectives of this effort were to identify methods capable of detecting the fatigue crack and to determine how far in advance of total failure positive detection was given. Results show that the fault detection methods failed to respond to the fatigue crack prior to complete rim fracture in the thin rim gear tests. In the standard full rim gear test all of the methods responded to the fatigue crack in advance of tooth fracture; however, only three of the methods responded to the fatigue crack in the early stages of crack propagation.

The V sign in lateral talar process fractures: an experimental study using a foot and ankle model.

PubMed

Jentzsch, Thorsten; Hasler, Anita; Renner, Niklas; Peterhans, Manuel; Sutter, Reto; Espinosa, Norman; Wirth, Stephan H

2017-07-03

Lateral talar process fractures (LTPF) are often missed on conventional radiographs. A positive V sign is an interruption of the contour of the LTP. It has been suggested, but not proven to be pathognomonic for LTPF. The objective was to study whether the V sign is pathognomonic for LTPF and if it can be properly assessed in different ankle positions and varying fracture types. An experimental study was conducted. Two investigators assessed lateral radiographs (n = 108) of a foot and ankle model. The exposure variables were different ankle positions and fracture types. The primary outcome was the correct detection of a V sign. The secondary outcomes were the detection of the V sign depending on ankle position and fracture type as well as the uncertainty. The interobserver agreement on the V sign and type of fracture were fair (κ = 0.35, 95% CI 0.18-0.53, p < 0.001 and κ = 0.37, 95% CI 0.26-0.48, p < 0.001). The mean sensitivity, specificity, PPV, NPV, and likelihood ratio for the detection of the V sign were 77% (95% CI 67-86%), 59% (95% CI 39-78%), 85% (95% CI 75-92%), 46% (95% CI 29-63%), and 2. The mean uncertainty in the V sign detection was 38%. The V sign identification stratified by ankle position and fracture type showed significant better results with increasing inversion (p = 0.035 and p = 0.011) and type B fractures (p = 0.001 and p = 0.013). The V sign may not be pathognomonic and is not recommended as the only modality for the detection of LTPF. It is better visualized with inversion, but does not depend on plantar flexion or internal rotation. It is also better seen in type B fractures. It is difficult to detect and investigator-dependent. It may be helpful in a clinical setting to point into a direction, but a CT scan may be used if in doubt about a LTPF.

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Liou, Ya-Hsuan; Teng, Mao-Hua; Liu, Ching-Yi; Lee, Tsai-Ping

2016-11-01

Recent advances in borehole geophysical techniques have improved characterization of cross-hole fracture flow. The direct detection of preferential flow paths in fractured rock, however, remains to be resolved. In this study, a novel approach using nanoscale zero-valent iron (nZVI or `nano-iron') as a tracer was developed for detecting fracture flow paths directly. Generally, only a few rock fractures are permeable while most are much less permeable. A heat-pulse flowmeter can be used to detect changes in flow velocity for delineating permeable fracture zones in the borehole and providing the design basis for the tracer test. When nano-iron particles are released in an injection well, they can migrate through the connecting permeable fracture and be attracted to a magnet array when arriving in an observation well. Such an attraction of incoming iron nanoparticles by the magnet can provide quantitative information for locating the position of the tracer inlet. A series of field experiments were conducted in two wells in fractured rock at a hydrogeological research station in Taiwan, to test the cross-hole migration of the nano-iron tracer through permeable connected fractures. The fluid conductivity recorded in the observation well confirmed the arrival of the injected nano-iron slurry. All of the iron nanoparticles attracted to the magnet array in the observation well were found at the depth of a permeable fracture zone delineated by the flowmeter. This study has demonstrated that integrating the nano-iron tracer test with flowmeter measurement has the potential to characterize preferential flow paths in fractured rock.

Bilateral trampoline fracture of the proximal tibia in a child.

PubMed

Arkink, Enrico B; van der Plas, Annelies; Sneep, Ruth W; Reijnierse, Monique

2017-12-01

Trampoline fractures are transversely oriented impaction fractures of the proximal tibia sustained by young children jumping on a trampoline. Unaware of the mechanism of this specific nontraumatic fracture, physicians may fail to detect these fractures on plain radiographs, as radiological findings may be very subtle. In this case report, we present a rare case of bilateral trampoline fractures with an explanation of the trauma mechanism.

Case-based fracture image retrieval.

PubMed

Zhou, Xin; Stern, Richard; Müller, Henning

2012-05-01

Case-based fracture image retrieval can assist surgeons in decisions regarding new cases by supplying visually similar past cases. This tool may guide fracture fixation and management through comparison of long-term outcomes in similar cases. A fracture image database collected over 10 years at the orthopedic service of the University Hospitals of Geneva was used. This database contains 2,690 fracture cases associated with 43 classes (based on the AO/OTA classification). A case-based retrieval engine was developed and evaluated using retrieval precision as a performance metric. Only cases in the same class as the query case are considered as relevant. The scale-invariant feature transform (SIFT) is used for image analysis. Performance evaluation was computed in terms of mean average precision (MAP) and early precision (P10, P30). Retrieval results produced with the GNU image finding tool (GIFT) were used as a baseline. Two sampling strategies were evaluated. One used a dense 40 × 40 pixel grid sampling, and the second one used the standard SIFT features. Based on dense pixel grid sampling, three unsupervised feature selection strategies were introduced to further improve retrieval performance. With dense pixel grid sampling, the image is divided into 1,600 (40 × 40) square blocks. The goal is to emphasize the salient regions (blocks) and ignore irrelevant regions. Regions are considered as important when a high variance of the visual features is found. The first strategy is to calculate the variance of all descriptors on the global database. The second strategy is to calculate the variance of all descriptors for each case. A third strategy is to perform a thumbnail image clustering in a first step and then to calculate the variance for each cluster. Finally, a fusion between a SIFT-based system and GIFT is performed. A first comparison on the selection of sampling strategies using SIFT features shows that dense sampling using a pixel grid (MAP = 0.18) outperformed the SIFT detector-based sampling approach (MAP = 0.10). In a second step, three unsupervised feature selection strategies were evaluated. A grid parameter search is applied to optimize parameters for feature selection and clustering. Results show that using half of the regions (700 or 800) obtains the best performance for all three strategies. Increasing the number of clusters in clustering can also improve the retrieval performance. The SIFT descriptor variance in each case gave the best indication of saliency for the regions (MAP = 0.23), better than the other two strategies (MAP = 0.20 and 0.21). Combining GIFT (MAP = 0.23) and the best SIFT strategy (MAP = 0.23) produced significantly better results (MAP = 0.27) than each system alone. A case-based fracture retrieval engine was developed and is available for online demonstration. SIFT is used to extract local features, and three feature selection strategies were introduced and evaluated. A baseline using the GIFT system was used to evaluate the salient point-based approaches. Without supervised learning, SIFT-based systems with optimized parameters slightly outperformed the GIFT system. A fusion of the two approaches shows that the information contained in the two approaches is complementary. Supervised learning on the feature space is foreseen as the next step of this study.

Imaging in traumatic mandibular fractures

PubMed Central

Gemal, Hugo; Reed, Duncan

2017-01-01

A fracture of the mandible is a common trauma presentation amongst young males and represents one of the most frequently encountered fractured bones within the viscerocranium. Historically, assault was the dominant contributing factor but now due to the increased number of vehicles used per capita, motor vehicle accidents are the primary cause. Mandibular fractures can be classified anatomically, by dentition, by muscle group and by severity. The fracture may also be closed, open, comminuted, displaced or pathological. It is important that the imaging modality used identifies the classification as this will decide definitive treatment. X-ray projections have typically been used to detect a mandibular fracture, but are limited to an anteroposterior (AP), lateral and oblique view in an unstable trauma patient. These views are inadequate to detail the level of fracture displacement and show poor detail of the condylar region. Computer tomography (CT) is the imaging modality of choice when assessing a traumatic mandibular injury and can demonstrate a 100% sensitivity in detecting a fracture. This is through use of a multidetector-row CT, which reduces motion blur and therefore produces accurate coronal and sagittal reconstructions. Furthermore, reconstructive three-dimensional CT images gained from planar views, allows a better understanding of the spatial relationship of the fracture with other anatomical landmarks. This ensures a better appreciation of the severity and classification of a mandibular fracture, which therefore influences operative planning. Ultrasound is another useful modality in detecting a mandibular fracture when the patient is too unstable to be transferred to a CT scanner. The sensitivity however is less in comparison to a CT series of images and provides limited detail on the fracture pattern. Magnetic resonance imaging demonstrates use in assessing soft tissue injury of the temporomandibular joint but this is unlikely to be of priority when initially assessing a trauma patient. PMID:28932703

Remote Sensing of Subsurface Fractures in the Otway Basin, South Australia

NASA Astrophysics Data System (ADS)

Bailey, Adam; King, Rosalind; Holford, Simon; Hand, Martin

2013-04-01

A detailed understanding of naturally occurring fracture networks within the subsurface is becoming increasingly important to the energy sector, as the focus of exploration has expanded to include unconventional reservoirs such as coal seam gas, shale gas, tight gas, and engineered geothermal systems. Successful production from such reservoirs, where primary porosity and permeability is often negligible, is heavily reliant on structural permeability provided by naturally occurring and induced fracture networks, permeability, which is often not provided for through primary porosity and permeability. In this study the Penola Trough, located within the onshore Otway Basin in South Australia, is presented as a case study for remotely detecting and defining subsurface fracture networks that may contribute to secondary permeability. This area is prospective for shale and tight gas and geothermal energy. The existence and nature of natural fractures is verified through an integrated analysis of geophysical logs (including wellbore image logs) and 3D seismic data. Wellbore image logs from 11 petroleum wells within the Penola Trough were interpreted for both stress indicators and natural fractures. A total of 507 naturally occurring fractures were identified, striking approximately WNE-ESE. Fractures which are aligned in the in-situ stress field are optimally oriented for reactivation, and are hence likely to be open to fluid flow. Fractures are identifiable as being either resistive or conductive sinusoids on the resistivity image logs used in this study. Resistive fractures, of which 239 were identified, are considered to be cemented with electrically resistive cements (such as quartz or calcite) and thus closed to fluid flow. Conductive fractures, of which 268 were identified, are considered to be uncemented and open to fluid flow, and thus important to geothermal exploration. Fracture susceptibility diagrams constructed for the identified fractures illustrate that the conductive fractures are optimally oriented for reactivation in the present-day strike-slip fault regime, and so are likely to be open to fluid flow. To gain an understanding of the broader extent of these natural fractures, it is necessary to analyse more regional 3D seismic data. It is well documented that fault and fracture networks like those generally observed in image logs lie well below seismic amplitude resolution, making them difficult to observe directly on amplitude data. However, seismic attributes can be calculated to provide some information on sub-seismic scale structural and stratigraphic features. Using the merged Balnaves/Haselgrove 3D seismic cube acquired over the Penola Trough, attribute maps of complex multi-trace dip-steered coherency and most positive curvature, among others, were used to document the presence of discontinuities within the seismic data which area likely to represent natural fractures, and to best constrain the likely extent of the fracture network which they form. The resulting fracture network model displays relatively good connectivity surrounding structural features intersecting the studied horizons, although large areas lacking significant discontinuities are observed. These areas make it unlikely that the fracture network contributes to permeability on a basin-wide scale, though observed features are optimally oriented for reactivation under contemporary stress conditions and are thus likely to provide at least local increases in permeability.

Microearthquake Studies at the Salton Sea Geothermal Field

DOE Data Explorer

Templeton, Dennise

2013-10-01

The objective of this project is to detect and locate microearthquakes to aid in the characterization of reservoir fracture networks. Accurate identification and mapping of the large numbers of microearthquakes induced in EGS is one technique that provides diagnostic information when determining the location, orientation and length of underground crack systems for use in reservoir development and management applications. Conventional earthquake location techniques often are employed to locate microearthquakes. However, these techniques require labor-intensive picking of individual seismic phase onsets across a network of sensors. For this project we adapt the Matched Field Processing (MFP) technique to the elastic propagation problem in geothermal reservoirs to identify more and smaller events than traditional methods alone.

Monitoring Induced Fractures with Electrical Measurements using Depth to Surface Resistivity: A Field Case Study

NASA Astrophysics Data System (ADS)

Wilt, M.; Nieuwenhuis, G.; Sun, S.; MacLennan, K.

2016-12-01

Electrical methods offer an attractive option to map induced fractures because the recovered anomaly is related to the electrical conductivity of the injected fluid in the open (propped) section of the fracture operation. This is complementary to existing micro-seismic technology, which maps the mechanical effects of the fracturing. In this paper we describe a 2014 field case where a combination of a borehole casing electrode and a surface receiver array was used to monitor hydrofracture fracture creation and growth in an unconventional oil field project. The fracture treatment well was 1 km long and drilled to a depth of 2.2 km. Twelve fracture events were induced in 30 m intervals (stages) in the 1 km well. Within each stage 5 events (clusters) were initiated at 30 m intervals. Several of the fracture stages used a high salinity brine, instead of fresh water, to enhance the electrical signal. The electrical experiment deployed a downhole source in a well parallel to the treatment well and 100 m away. The source consisted of an electrode attached to a wireline cable into which a 0.25 Hz square wave was injected. A 60-station electrical field receiver array was placed above the fracture and extending for several km. Receivers were oriented to measure electrical field parallel with the presumed fracture direction and those perpendicular to it. Active source electrical data were collected continuously during 7 frac stages, 3 of which used brine as the frac fluid over a period of several days. Although the site was quite noisy and the electrical anomaly small we managed to extract a clear frac anomaly using field separation, extensive signal averaging and background noise rejection techniques. Preliminary 3D modeling, where we account for current distribution of the casing electrode and explicitly model multiple thin conductive sheets to represent fracture stages, produces a model consistent with the field measurements and also highlights the sensitivity of the measurements to the high salinity frac stages. Data inversion is presently ongoing.

Dissolution along faults-fractures and hypogenic karst in carbonates: examples from Brazil

NASA Astrophysics Data System (ADS)

Ennes-Silva, Renata; Cazarin, Caroline; Bezerra, Francisco; Auler, Augusto; Klimchouk, Alexander

2015-04-01

Dissolution along faults-fractures and hypogenic karst in carbonates: examples from Brazil Ennes-Silva, R.A; Cazarin, C.L.; Bezerra, F.H.; Auler, A.S.; Klimchouk, A.B. Dissolution along zones of preferential flow enhances anisotropy in geological media and increases its complexity. Changes in parameters such as porosity and permeability due to diagenesis and presence of ascendant fluids along fractures and faults can be responsible for hypogenic karstic system. The present study investigates the relationship between lithofacies, tectonics and karstification in the Neoproterozoic Salitre Formation, located in the central-eastern Brazil. This unit comprises several systems of caves including the Toca da Boa Vista and da Barriguda hypogenic caves, the largests in South America, and focus of this study. We focused on cave mapping and morphogenetic analysis, determination of petrophysical properties, thin-section description, micro-tomography, and isotopic analysis. The Salitre Formation, deposited in an epicontinental sea, comprises mud/wakestones, grainstones, microbial facies, and fine siliciclastic rocks. Passages occur in several levels within ca. 60 m thick cave-forming section, limited at the top by lithofacies with low permeability and fractures. Cave development occurred in phreatic sluggish-flow environment with overall upwelling flow. Fluids rise via cross-formational fractures and were distributed laterally within the cave-forming section using geological heterogeneities to eventually discharge up through outlets breaching across the upper confining beds. Maps of conduits show preferred directions for development of conduits: NNE-SSW and E-W. These two directions represents a relation between structures and hypogenic morphology. Joints, axis fold and fractures allowed pathways to the fluid rises, and then development of channels of entrance (feeders), outputs (outlets) and some cupolas, which are clearly aligned to fractures. Our data indicate several events of porosity evolution, such as subaerial exposure, folds and fractures, hydrothermal events (exotic minerals assemblage), sulfuric acid dissolution, dissolution at the water table, condensation corrosion, and faults and fractures reactivation. The major enhancement of secondary porosity was due to hypogene speleogenesis.

A Fractal Interpretation of Controlled-Source Helicopter Electromagnetic Survey Data: Seco Creek, Edwards Aquifer, TX

NASA Astrophysics Data System (ADS)

Decker, K. T.; Everett, M. E.

2009-12-01

The Edwards aquifer lies in the structurally complex Balcones fault zone and supplies water to the growing city of San Antonio. To ensure that future demands for water are met, the hydrological and geophysical properties of the aquifer must be well-understood. In most settings, fracture lengths and displacements occur in power-law distributions. Fracture distribution plays an important role in determining electrical and hydraulic current flowpaths. 1-D synthetic models of the controlled-source electromagnetic (CSEM) response for layered models with a fractured layer at depth described by the roughness parameter βV, such that 0≤βV<1, associated with the power-law length-scale dependence of electrical conductivity are developed. A value of βV = 0 represents homogeneous, continuous media, while a value of 0<βV<1 shows that roughness exists. The Seco Creek frequency-domain helicopter electromagnetic survey data set is analyzed by introducing the similarly defined roughness parameter βH to detect lateral roughness along survey lines. Fourier transforming the apparent resistivity as a function of position along flight line into wavenumber domain using a 256-point sliding window gives the power spectral density (PSD) plot for each line. The value of βH is the slope of the least squares regression for the PSD in each 256-point window. Changes in βH with distance along the flight line are plotted. Large values of βH are found near well-known large fractures and maps of βH produced by interpolating values of βH along survey lines suggest previously undetected structure at depth.

[Conventional X-Rays of Ankle Joint Fractures in Older Patients are Not Always Predictive].

PubMed

Jubel, A; Faymonville, C; Andermahr, J; Boxberg, S; Schiffer, G

2017-02-01

Background: Ankle fractures are extremely common in the elderly, with an incidence of up to 39 fractures per 100,000 persons per year. We found a discrepancy between intraoperative findings and preoperative X-ray findings. It was suggested that many relevant lesions of the ankle joint in the elderly cannot be detected with plain X-rays. Methods: Complete data sets and preoperative X-rays of 84 patients aged above 60 years with ankle fractures were analysed retrospectively. There were 59 women and 25 men, with a mean age of 69.9 years. Operation reports and preoperative X-rays were analysed with respect to four relevant lesions: multifragmentary fracture pattern of the lateral malleolus, involvement of the medial malleolus, posterior malleolar fractures and bony avulsion of anterior syndesmosis. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy and prevalence were calculated. Results: The prevalence of specific ankle lesions in the analyzed cohort was 24 % for the multifragmentary fracture pattern of the lateral malleolus, 38 % for fractures of the medial malleolus, 25 % for posterior malleolar fractures and 22.6 % for bony avulsions of the anterior syndesmosis. Multifragmentary fracture patterns of the lateral malleolus (sensitivity 0 %) and bony avulsions of the anterior syndesmosis (sensitivity 5 %) could not be detected in plain X-rays of the ankle joint at all. Fractures of the medial malleolus and involvement of the dorsal tibial facet were detected with a sensitivity of 96.8 % and 76.2 %, respectively, and specificity of 100 % in both cases. Conclusions: This study confirms that complex fracture patterns, such as multifragmentary involvement of the lateral malleolus, additional fracture of the medial malleolus, involvement of the dorsal tibial facet or bony avulsion of the anterior syndesmosis are common in ankle fractures of the elderly. Therefore, CT scans should be routinely considered for primary diagnosis, in addition to plain X-rays. Georg Thieme Verlag KG Stuttgart · New York.

Comparison of ultrasonography and radiography in diagnosis of rib fractures.

PubMed

Pishbin, Elham; Ahmadi, Koorosh; Foogardi, Molood; Salehi, Maryam; Seilanian Toosi, Farrokh; Rahimi-Movaghar, Vafa

2017-08-01

Rib fractures are the most common skeletal thoracic injuries resulting from blunt chest trauma. Half of the rib fractures are not detected upon a precise physical evaluation and radiographs. Recently ultrasonography (USG) has been investigated to detect rib fractures. But based on literature the usefulness of USG varies widely. This study was conducted to investigate the role of USG in the detection of possible rib fractures in comparison with radiography. In this cross-sectional study, consecutive patients with minor blunt chest trauma and suspected rib fractures presenting in Imam Reza Hospital located in Mashhad-Iran, between April 2013 and October 2013 were assessed by USG and radiography. The radiography was performed in a posteroanterior (PA) chest projection and oblique rib view centered over the area of trauma. The time duration spent in taking USG and radiography were recorded. The prevalence and location of fractures revealed by USG and radiography were compared. Sixty-one suspected patients were assessed. The male to female ratio was 2.4:1 (43 men and 18 women) with a mean ± SD age of (44.3 ± 19.7) years. There were totally 59 rib fractures in 38 (62.3%) patients based on radiography and USG, while 23 (37.7%) patients had no diagnostic evidence of rib lesions. USG revealed 58 rib fractures in 33 (54.1%) of 61 suspected patients and radiographs revealed 32 rib fractures in 20 (32.8%) of 61 patients. A total of 58 (98.3%) rib fractures were detected by USG, whereas oblique rib view and PA chest radiography showed 27 (45.8%) and 24 (40.7%) rib fractures, respectively. The average duration of USG was (12 ± 3) min (range 7-17 min), whereas the duration of radiography was (27 ± 6) min (range 15-37 min). The kappa coefficient showed a low level of agreement between both USG and PA chest radiography (kappa coefficient = 0.28), and between USG and oblique rib view (kappa coefficient = 0.32). USG discloses more fractures than radiography in most patients presenting with suspected rib fractures. Moreover USG requires significantly less time than radiography. Copyright © 2017 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

Geophysical investigations of well fields to characterize fractured-bedrock aquifers in southern New Hampshire

USGS Publications Warehouse

Degnan, James R.; Moore, Richard Bridge; Mack, Thomas J.

2001-01-01

Bedrock-fracture zones near high-yield bedrock wells in southern New Hampshire well fields were located and characterized using seven surface and six borehole geophysical survey methods. Detailed surveys of six sites with various methods provide an opportunity to integrate and compare survey results. Borehole geophysical surveys were conducted at three of the sites to confirm subsurface features. Hydrogeologic settings, including a variety of bedrock and surface geologic materials, were sought to gain an insight into the usefulness of the methods in varied terrains. Results from 15 survey lines, 8 arrays, and 3 boreholes were processed and interpreted from the 6 sites. The surface geophysical methods used provided physical properties of fractured bedrock. Seismic refraction and ground-penetrating radar (GPR) primarily were used to characterize the overburden materials, but in a few cases indicated bedrock-fracture zones. Magnetometer surveys were used to obtain background information about the bedrock to compare with other results, and to search for magnetic lows, which may result from weathered fractured rock. Electromagnetic terrain conductivity surveys (EM) and very-low-frequency electromagnetic surveys (VLF) were used as rapid reconnaissance techniques with the primary purpose of identifying electrical anomalies, indicating potential fracture zones in bedrock. Direct-current (dc) resistivity methods were used to gather detailed subsurface information about fracture depth and orientation. Two-dimensional (2-D) dc-resistivity surveys using dipole-dipole and Schlumberger arrays located and characterized the overburden, bedrock, and bedrock-fracture zones through analysis of data inversions. Azimuthal square array dc-resistivity survey results indicated orientations of conductive steep-dipping bedrock-fracture zones that were located and characterized by previously applied geophysical methods. Various available data sets were used for site selection, characterizations, and interpretations. Lineament data, developed as a part of a statewide and regional scale investigation of the bedrock aquifer, were available to identify potential near-vertical fracture zones. Geophysical surveys indicated fracture zones coincident with lineaments at 4 of the sites. Geologic data collected as a part of the regional scale investigation provided outcrop fracture measurements, ductile fabric, and contact information. Dominant fracture trends correspond to the trends of geophysical anomalies at 4 of the sites. Water-well drillers? logs from water supply and environmental data sets also were used where available to characterize sites. Regional overburden information was compiled from stratified-drift aquifer maps and surficial-geological maps.

Evaluation of ground-penetrating radar to detect free-phase hydrocarbons in fractured rocks - Results of numerical modeling and physical experiments

USGS Publications Warehouse

Lane, J.W.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.

2000-01-01

The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.

Optimization of Tube Current in Cone-beam Computed Tomography for the Detection of Vertical Root Fractures with Different Intracanal Materials.

PubMed

Gaêta-Araujo, Hugo; Silva de Souza, Gabriela Queiroz; Freitas, Deborah Queiroz; de Oliveira-Santos, Christiano

2017-10-01

There is no consensus about the accuracy of cone-beam computed tomography (CBCT) for detecting vertical root fractures (VRFs), nor is there certainty about the isolated effect of different tube current parameters on the diagnosis of VRF through CBCT scans. This study aimed to evaluate how tube current affects the detection of VRF on CBCT examinations in the absence of intracanal materials and in the presence of gutta-percha (GP) and metal (MP) or fiberglass (FP) intracanal posts. The sample consisted of 320 CBCT scans of tooth roots with and without VRF divided into 8 groups: no fracture/no intracanal material; no fracture + GP; no fracture + MP; no fracture + FP; fracture/no intracanal material; fracture + GP; fracture + MP; fracture + FP. The scans were acquired with an OP300 unit using 4 different milliamperes (4 mA, 8 mA, 10 mA, 13 mA). Five oral radiologists analyzed the images. The area under the receiver operating characteristic curve (Az), sensitivity, specificity, positive and negative predictive values, and interobserver agreement were calculated. Diagnostic performance for the different milliamperes tested was similar for teeth without root filling materials or with FP. Teeth with GP and MP showed the highest Az values for 8 mA and 10 mA, respectively. For teeth with MP, specificity was significantly higher when 10 mA was used. For teeth without root filling materials or with FP, the use of a reduced milliampere does not seem to influence the detection of VRF in a significant manner. For teeth with GP and MP, an increased milliampere may lead to increased diagnostic performance. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Long-period long-duration seismic events during hydraulic fracturing: Implications for tensile fracture development

NASA Astrophysics Data System (ADS)

Hu, Hongru; Li, Aibing; Zavala-Torres, Ricardo

2017-05-01

Long-period long-duration (LPLD) seismic events are observed from a microseismic data set acquired by surface receivers in the Eagle Ford Shale. These events are characterized by low frequencies of 10-60 Hz and long durations of 30-60 s. The seismograms are dominated with P waves, and the frequency spectra have peaks at several isolated frequencies, similar to volcanic tremors. The LPLD events are located close to the horizontal hydraulic treatment well and migrate away from the well with time. These observations suggest that the LPLD events are related to hydraulic fracturing and are possibly caused by the jerky opening and resonance of fluid-filled cracks. Imaging this type of LPLD events can potentially map fluid flow and tensile fracture development during hydraulic fracturing.

New software for 3D fracture network analysis and visualization

NASA Astrophysics Data System (ADS)

Song, J.; Noh, Y.; Choi, Y.; Um, J.; Hwang, S.

2013-12-01

This study presents new software to perform analysis and visualization of the fracture network system in 3D. The developed software modules for the analysis and visualization, such as BOUNDARY, DISK3D, FNTWK3D, CSECT and BDM, have been developed using Microsoft Visual Basic.NET and Visualization TookKit (VTK) open-source library. Two case studies revealed that each module plays a role in construction of analysis domain, visualization of fracture geometry in 3D, calculation of equivalent pipes, production of cross-section map and management of borehole data, respectively. The developed software for analysis and visualization of the 3D fractured rock mass can be used to tackle the geomechanical problems related to strength, deformability and hydraulic behaviors of the fractured rock masses.

Microseismic and deformation imaging of hydraulic fracture growth and geometry in the C sand interval, GRI/DOE M-Site project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.; Uhl, J.E.; Engler, B.P.

Six hydraulic-fracture injections into a fluvial sandstone at a depth of 4300 ft were monitored with multi-level tri-axial seismic receivers in two wells and an inclinometer array in one well, resulting in maps of the growth and final geometry of each fracture injection. These diagnostic images show the progression of height and length growth with fluid volume, rate and viscosity. Complexities associated with shut downs and high treatment pressures can be observed. Validation of the seismic geometry was made with the inclinometers and diagnostic procedures in an intersecting well. Fracture information related to deformation, such as fracture closure pressure, residualmore » widths, and final prop distribution, were obtained from the inclinometer data.« less

Conformal dynamics of precursors to fracture

NASA Astrophysics Data System (ADS)

Barra, F.; Herrera, M.; Procaccia, I.

2003-09-01

An exact integro-differential equation for the conformal map from the unit circle to the boundary of an evolving cavity in a stressed 2-dimensional solid is derived. This equation provides an accurate description of the dynamics of precursors to fracture when surface diffusion is important. The solution predicts the creation of sharp grooves that eventually lead to material failure via rapid fracture. Solutions of the new equation are demonstrated for the dynamics of an elliptical cavity and the stability of a circular cavity under biaxial stress, including the effects of surface stress.

Fracture related-fold patterns analysis and hydrogeological implications: Insight from fault-propagation fold in Northwestern of Tunisia

NASA Astrophysics Data System (ADS)

Sanai, L.; Chenini, I.; Ben Mammou, A.; Mercier, E.

2015-01-01

The spatial distribution of fracturing in hard rocks is extremely related to the structural profile and traduces the kinematic evolution. The quantitative and qualitative analysis of fracturing combined to GIS techniques seem to be primordial and efficient in geometric characterization of lineament's network and to reconstruct the relative timing and interaction of the folding and fracturing histories. Also a detailed study of the area geology, lithology, tectonics, is primordial for any hydrogeological study. For that purpose we used a structural approach that consist in comparison between fracture sets before and after unfolding completed by aerospace data and DEM generated from topographic map. The above methodology applied in this study carried out in J. Rebia located in Northwestern of Tunisia demonstrated the heterogeneity of fracturing network and his relation with the fold growth throught time and his importance on groundwater flow.

Graph Representations of Flow and Transport in Fracture Networks using Machine Learning

NASA Astrophysics Data System (ADS)

Srinivasan, G.; Viswanathan, H. S.; Karra, S.; O'Malley, D.; Godinez, H. C.; Hagberg, A.; Osthus, D.; Mohd-Yusof, J.

2017-12-01

Flow and transport of fluids through fractured systems is governed by the properties and interactions at the micro-scale. Retaining information about the micro-structure such as fracture length, orientation, aperture and connectivity in mesh-based computational models results in solving for millions to billions of degrees of freedom and quickly renders the problem computationally intractable. Our approach depicts fracture networks graphically, by mapping fractures to nodes and intersections to edges, thereby greatly reducing computational burden. Additionally, we use machine learning techniques to build simulators on the graph representation, trained on data from the mesh-based high fidelity simulations to speed up computation by orders of magnitude. We demonstrate our methodology on ensembles of discrete fracture networks, dividing up the data into training and validation sets. Our machine learned graph-based solvers result in over 3 orders of magnitude speedup without any significant sacrifice in accuracy.

Comparison of explicit finite element and mechanical simulation of the proximal femur during dynamic drop-tower testing.

PubMed

Ariza, O; Gilchrist, S; Widmer, R P; Guy, P; Ferguson, S J; Cripton, P A; Helgason, B

2015-01-21

Current screening techniques based on areal bone mineral density (aBMD) measurements are unable to identify the majority of people who sustain hip fractures. Biomechanical examination of such events may help determine what predisposes a hip to be susceptible to fracture. Recently, drop-tower simulations of in-vitro sideways falls have allowed the study of the mechanical response of the proximal human femur at realistic impact speeds. This technique has created an opportunity to validate explicit finite element (FE) models against dynamic test data. This study compared the outcomes of 15 human femoral specimens fractured using a drop tower with complementary specimen-specific explicit FE analysis. Correlation coefficient and root mean square error (RMSE) were found to be moderate for whole bone stiffness comparison (R(2)=0.3476 and 22.85% respectively). No correlation was found between experimentally and computationally predicted peak force, however, energy absorption comparison produced moderate correlation and RMSE (R(2)=0.4781 and 29.14% respectively). By comparing predicted strain maps to high speed video data we demonstrated the ability of the FE models to detect vulnerable portions of the bones. Based on our observations, we conclude that there exists a need to extend the current apparent level material models for bone to cover higher strain rates than previously tested experimentally. Copyright © 2014 Elsevier Ltd. All rights reserved.

Artificial intelligence in fracture detection: transfer learning from deep convolutional neural networks.

PubMed

Kim, D H; MacKinnon, T

2018-05-01

To identify the extent to which transfer learning from deep convolutional neural networks (CNNs), pre-trained on non-medical images, can be used for automated fracture detection on plain radiographs. The top layer of the Inception v3 network was re-trained using lateral wrist radiographs to produce a model for the classification of new studies as either "fracture" or "no fracture". The model was trained on a total of 11,112 images, after an eightfold data augmentation technique, from an initial set of 1,389 radiographs (695 "fracture" and 694 "no fracture"). The training data set was split 80:10:10 into training, validation, and test groups, respectively. An additional 100 wrist radiographs, comprising 50 "fracture" and 50 "no fracture" images, were used for final testing and statistical analysis. The area under the receiver operator characteristic curve (AUC) for this test was 0.954. Setting the diagnostic cut-off at a threshold designed to maximise both sensitivity and specificity resulted in values of 0.9 and 0.88, respectively. The AUC scores for this test were comparable to state-of-the-art providing proof of concept for transfer learning from CNNs in fracture detection on plain radiographs. This was achieved using only a moderate sample size. This technique is largely transferable, and therefore, has many potential applications in medical imaging, which may lead to significant improvements in workflow productivity and in clinical risk reduction. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Tracer Tests in the Fractured Rock to Investigate Preferential Groundwater Flow

NASA Astrophysics Data System (ADS)

Chan, W.; Chung, L.; Lee, T.; Liu, C.; Chia, Y.; Teng, M.

2012-12-01

Hydraulic tests are often used to obtain hydraulic conductivity in the aquifer. Test results usually reflect the average hydraulic conductivity in the surrounding strat. However, in fractured rock, groundwater flows primarily through a few fractures. Saltwater tracer test can be used to detect the direction of groundwater flow, but it was difficult to know the hydraulic connectivity between fractures. In this study, we use a variety of field tests, including tracer test, hydraulic test, and heat-pulse flowmeter test, to locate the permeable fractures and detect the hydraulic connections between boreholes. There are eight test wells and two observation wells on field experimental site in central Taiwan. Geological survey results show that there are at least three sets of joint planes. In order to realize the location of the preferential pathway of groundwater flow, heat-pulse flowmeter measurement was adopted to identify the depth of permeable fractures. Multi-well pumping test was also performed to investigate the hydraulic connectivity between these wells. Tracer tests were then used to detect the hydraulic connectivity of permeable fractures between two wells. Injection of nano zero valent iron in one well and and collection of iron tracer with a magnet array in the other well can specifically locate the permeable fracture and determine the connectivity. Saltwater tracer test result can be used to support that of nano-iron tracer test, and verify the relationship between well water conductivity increases and rock fracture location. The results show that tracer test is a useful tool to investigate the preferential groundwater flow in the fractured rock, but it is essential to flush the mud in fractures prior to the test.

Impact Processes in the Solar System

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.

2004-01-01

Our laboratory has previously conducted impact fracture and dynamic failure tests. Polanskey and Ahrens [1990] mapped the fractures from a series of laboratory craters (Fig. 1) and Ahrens and Rubin [ 1993] inferred that the usually further extending radial cracks resulted from tensional failure during the compression of the shock propagation. The radial spreading induced by the particle velocity field caused the stresses perpendicular to the shock front to become sufficiently large and tensile. This induces "radial fractures." The concentric fractures are attributed to the tensional failure occurring after the initial compressive phase. Upon radial propagation of the stress wave the negative tension behind the stress-wave front caused failure along the quasi-spherical concentric fractures. The near-surface and spall fractures are attributed to the fractures described by Melosh [1984]. These are activated by impact and can launch relatively unshocked samples of planetary surfaces to speeds exceeding escape velocity. In the case of Mars, some of these surface samples presumably become the SNC (Mars) meteorites.

Bedrock geologic map of the Worcester South quadrangle, Worcester County, Massachusetts

USGS Publications Warehouse

Walsh, Gregory J.; Merschat, Arthur J.

2015-09-29

The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing hydrogeologic characterization of the fractured bedrock of Massachusetts. This report presents mapping by Gregory J. Walsh and Arthur J. Merschat from 2008 to 2010. The report consists of a map and GIS database, both of which are available for download at http://dx.doi.org/ 10.3133/sim3345. The database includes contacts of bedrock geologic units, faults, outcrop locations, structural information, and photographs.

Visual texture for automated characterisation of geological features in borehole televiewer imagery

NASA Astrophysics Data System (ADS)

Al-Sit, Waleed; Al-Nuaimy, Waleed; Marelli, Matteo; Al-Ataby, Ali

2015-08-01

Detailed characterisation of the structure of subsurface fractures is greatly facilitated by digital borehole logging instruments, the interpretation of which is typically time-consuming and labour-intensive. Despite recent advances towards autonomy and automation, the final interpretation remains heavily dependent on the skill, experience, alertness and consistency of a human operator. Existing computational tools fail to detect layers between rocks that do not exhibit distinct fracture boundaries, and often struggle characterising cross-cutting layers and partial fractures. This paper presents a novel approach to the characterisation of planar rock discontinuities from digital images of borehole logs. Multi-resolution texture segmentation and pattern recognition techniques utilising Gabor filters are combined with an iterative adaptation of the Hough transform to enable non-distinct, partial, distorted and steep fractures and layers to be accurately identified and characterised in a fully automated fashion. This approach has successfully detected fractures and layers with high detection accuracy and at a relatively low computational cost.

Three dimensional fracture aperture and porosity distribution using computerized tomography

NASA Astrophysics Data System (ADS)

Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

2017-12-01

A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the presence of strong heterogeneities in fracture aperture at the mm-scale. These results exemplify the use of non-destructive imaging to determine fracture aperture maps, which can be used to address flow channelization and heat transfer that cannot be obtained from core-flooding experiments alone.

Ceres' deformational surface features compared to other planetary bodies.

NASA Astrophysics Data System (ADS)

von der Gathen, Isabel; Jaumann, Ralf; Krohn, Katrin; Buczkowski, Debra L.; Elgner, Stephan; Kersten, Elke; Matz, Klaus-Dieter; Nass, Andrea; Otto, Katharina; Preusker, Frank; Roatsch, Thomas; Schröder, Stefanus E.; Schulzeck, Franziska; Stephan, Katrin; Wagner, Roland; De Sanctis, Maria C.; Schenk, Paul; Scully, Jennifer E. C.; Williams, Dave A.; Raymond, Carol A.

2016-04-01

On March 2015, NASA's Dawn spacecraft arrived at the dwarf planet Ceres and has been providing images of its surface. Based on High Altitude Mapping Orbiter (HAMO) clear filter images (140 m/px res.), a Survey mosaic (~400 m/px) and a series of Low Altitude Mapping Orbiter (LAMO) clear filter images (35 m/px) of the Dawn mission [1], deformational features are identified on the surface of Ceres. In order to further our knowledge about the nature and origin of these features, we start a comparative analysis of similar features on different planetary bodies, like Enceladus, Ganymede and the Moon, based on images provided by the Cassini, Galileo and Lunar Orbiter mission. This study focuses on the small scale fractures, mostly located on Ceres' crater floors, in comparison with crater fractures on the planetary bodies named above. The fractures were analyzed concerning the morphology and shape, the distribution, orientation and possible building mechanisms. On Ceres, two different groups of fractures are distinct. The first one includes fractures, normally arranged in subparallel pattern, which are usually located on crater floors, but also on crater rims. Their sense of direction is relatively uniform but in some cases they get deformed by shearing. The second group consists of joint systems, which spread out of one single location, sometimes arranged concentric to the crater rim. They were likely formed by cooling-melting processes linked to the impact process or up doming material. Fractures located on crater floors are also common on the icy satellite Enceladus [3]. While Enceladus' fractures don't seem to have a lot in common compared to those on Ceres, we assume that similar fracture patterns and therefore similar building mechanism can be found e.g. on Ganymede and especially on the Moon [2]. Further work will include the comparison of the fractures with additional planetary bodies and the trial to explain why fracturing e.g. on Enceladus differs from that on Ceres. References: [1] Roatsch T. et al. (2016) PSS, in press. [2] Buczkowski D. L. (2016) LPSC. [3] Stephan, K. et al. (2013), in The Science of Solar System Ices, p. 279.

Cost-Effectiveness of Diagnostic Strategies for Suspected Scaphoid Fractures.

PubMed

Yin, Zhong-Gang; Zhang, Jian-Bing; Gong, Ke-Tong

2015-08-01

The aim of this study was to assess the cost effectiveness of multiple competing diagnostic strategies for suspected scaphoid fractures. With published data, the authors created a decision-tree model simulating the diagnosis of suspected scaphoid fractures. Clinical outcomes, costs, and cost effectiveness of immediate computed tomography (CT), day 3 magnetic resonance imaging (MRI), day 3 bone scan, week 2 radiographs alone, week 2 radiographs-CT, week 2 radiographs-MRI, week 2 radiographs-bone scan, and immediate MRI were evaluated. The primary clinical outcome was the detection of scaphoid fractures. The authors adopted societal perspective, including both the costs of healthcare and the cost of lost productivity. The incremental cost-effectiveness ratio (ICER), which expresses the incremental cost per incremental scaphoid fracture detected using a strategy, was calculated to compare these diagnostic strategies. Base case analysis, 1-way sensitivity analyses, and "worst case scenario" and "best case scenario" sensitivity analyses were performed. In the base case, the average cost per scaphoid fracture detected with immediate CT was $2553. The ICER of immediate MRI and day 3 MRI compared with immediate CT was $7483 and $32,000 per scaphoid fracture detected, respectively. The ICER of week 2 radiographs-MRI was around $170,000. Day 3 bone scan, week 2 radiographs alone, week 2 radiographs-CT, and week 2 radiographs-bone scan strategy were dominated or extendedly dominated by MRI strategies. The results were generally robust in multiple sensitivity analyses. Immediate CT and MRI were the most cost-effective strategies for diagnosing suspected scaphoid fractures. Economic and Decision Analyses Level II. See Instructions for Authors for a complete description of levels of evidence.

Application of Geologic Mapping Techniques and Autonomous Feature Detection to Future Exploration of Europa

NASA Astrophysics Data System (ADS)

Bunte, M. K.; Tanaka, K. L.; Doggett, T.; Figueredo, P. H.; Lin, Y.; Greeley, R.; Saripalli, S.; Bell, J. F.

2013-12-01

Europa's extremely young surface age, evidence for extensive resurfacing, and indications of a sub-surface ocean elevate its astrobiological potential for habitable environments and make it a compelling focus for study. Knowledge of the global distribution and timing of Europan geologic units is a key step in understanding the history of the satellite and for identifying areas relevant for exploration. I have produced a 1:15M scale global geologic map of Europa which represents a proportionate distribution of four unit types and associated features: plains, linea, chaos, and crater materials. Mapping techniques differ somewhat from other planetary maps but do provide a method to establish stratigraphic markers and to illustrate the surface history through four periods of formation as a function of framework lineament cross-cutting relationships. Correlations of observed features on Europa with Earth analogs enforce a multi-process theory for formation rather than the typical reliance on the principle of parsimony. Lenticulae and microchaos are genetically similar and most likely form by diapirism. Platy and blocky chaos units, endmembers of archetypical chaos, are best explained by brine mobilization. Ridges account for the majority of lineaments and may form by a number of methods indicative of local conditions; most form by either tidal pumping or shear heating. The variety of morphologies exhibited by bands indicates that multiple formation mechanisms apply once fracturing of the brittle surface over a ductile subsurface is initiated. Mapping results support the interpretation that Europa's shell has thickened over time resulting in changes in the style and intensity of deformation. Mapping serves as an index for change detection and classification, aids in pre-encounter targeting, and supports the selection of potential landing sites. Highest priority target areas are those which indicate geophysical activity by the presence of volcanic plumes, outgassing, or disrupted surface morphologies. Areas of high interest include lineaments and chaos margins. The limitations on detecting activity at these locations are approximated by studying similar observed conditions on other bodies. By adapting machine learning and data mining techniques to signatures of plumes and morphology, I have demonstrated autonomous rule-based detection of known features using edge-detection and supervised classification methods. These methods successfully detect ≤94% of known volcanic plumes or jets at Io, Enceladus, and comets. They also allow recognition of multiple feature types. Applying these results to conditions expected for Europa enables a prediction of the potential for detection of similar features and enables recommendations for mission concepts to increase the science return and efficiency of future missions to observe Europa. This post-Galileo view of Europa provides a synthesis of the overall history of this unique icy satellite and will be a useful frame of reference for future exploration of the jovian system and other potentially active outer solar system bodies.

Association between findings on palmarodorsal radiographic images and detection of a fracture in the proximal sesamoid bones of forelimbs obtained from cadavers of racing Thoroughbreds.

PubMed

Anthenill, Lucy A; Stover, Susan M; Gardner, Ian A; Hill, Ashley E; Lee, Christina M; Anderson, Mark L; Barr, Bradd C; Read, Deryck H; Johnson, Bill J; Woods, Leslie W; Daft, Barbara M; Kinde, Hailu; Moore, Janet D; Farman, Cynthia A; Odani, Jenee S; Pesavento, Patricia A; Uzal, Francisco A; Case, James T; Ardans, Alex A

2006-05-01

To determine the distribution for limbs and bones in horses with fractures of the proximal sesamoid bones and relationships with findings on palmarodorsal radiographic images. Proximal sesamoid bones obtained from both forelimbs of cadavers of 328 racing Thoroughbreds. Osteophytes; large vascular channels; and fracture location, orientation, configuration, and margin distinctness were categorized by use of high-detail contact palmarodorsal radiographs. Distributions of findings were determined. Relationships between radiographic findings and fracture characteristics were examined by use of chi2 and logistic regression techniques. Fractures were detected in 136 (41.5%) horses. Biaxial fractures were evident in 109 (80%) horses with a fracture. Osteophytes and large vascular channels were evident in 266 (81%) and 325 (99%) horses, respectively. Medial bones typically had complete transverse or split transverse simple fractures, indistinct fracture margins, > 1 vascular channel that was > 1 mm in width, and osteophytes in abaxial wing and basilar middle or basilar abaxial locations. Lateral bones typically had an oblique fracture and distinct fracture margins. Odds of proximal sesamoid bone fracture were approximately 2 to 5 times higher in bones without radiographic evidence of osteophytes or large vascular channels, respectively. Biaxial fractures of proximal sesamoid bones were common in cadavers of racing Thoroughbreds. Differences between medial and lateral bones for characteristics associated with fracture may relate to differences in fracture pathogeneses for these bones. Osteophytes and vascular channels were common findings; however, fractures were less likely to occur in bones with these features.

Stress Concentration and Fracture at Inter-variant Boundaries in an Al-Li Alloy

NASA Technical Reports Server (NTRS)

Crooks, Roy; Tayon, Wes; Domack, Marcia; Wagner, John; Beaudoin, Armand

2009-01-01

Delamination fracture has limited the use of lightweight Al-Li alloys. Studies of secondary, delamination cracks in alloy 2090, L-T fracture toughness samples showed grain boundary failure between variants of the brass texture component. Although the adjacent texture variants, designated B(sub s1) and B(sub s2), behave similarly during rolling, their plastic responses to mechanical tests can be quite different. EBSD data from through-thickness scans were used to generate Taylor factor maps. When a combined boundary normal and shear tensor was used in the calculation, the delaminating grains showed the greatest Taylor Factor differences of any grain pairs. Kernel Average Misorientation (KAM) maps also showed damage accumulation on one side of the interface. Both of these are consistent with poor slip accommodation from a crystallographically softer grain to a harder one. Transmission electron microscopy was used to confirm the EBSD observations and to show the role of slip bands in the development of large, interfacial stress concentrations. A viewgraph presentation accompanies the provided abstract.

Semi-automatic mapping of geological Structures using UAV-based photogrammetric data: An image analysis approach

NASA Astrophysics Data System (ADS)

Vasuki, Yathunanthan; Holden, Eun-Jung; Kovesi, Peter; Micklethwaite, Steven

2014-08-01

Recent advances in data acquisition technologies, such as Unmanned Aerial Vehicles (UAVs), have led to a growing interest in capturing high-resolution rock surface images. However, due to the large volumes of data that can be captured in a short flight, efficient analysis of this data brings new challenges, especially the time it takes to digitise maps and extract orientation data. We outline a semi-automated method that allows efficient mapping of geological faults using photogrammetric data of rock surfaces, which was generated from aerial photographs collected by a UAV. Our method harnesses advanced automated image analysis techniques and human data interaction to rapidly map structures and then calculate their dip and dip directions. Geological structures (faults, joints and fractures) are first detected from the primary photographic dataset and the equivalent three dimensional (3D) structures are then identified within a 3D surface model generated by structure from motion (SfM). From this information the location, dip and dip direction of the geological structures are calculated. A structure map generated by our semi-automated method obtained a recall rate of 79.8% when compared against a fault map produced using expert manual digitising and interpretation methods. The semi-automated structure map was produced in 10 min whereas the manual method took approximately 7 h. In addition, the dip and dip direction calculation, using our automated method, shows a mean±standard error of 1.9°±2.2° and 4.4°±2.6° respectively with field measurements. This shows the potential of using our semi-automated method for accurate and efficient mapping of geological structures, particularly from remote, inaccessible or hazardous sites.

Fracture-network 3D characterization in a deformed chalk reservoir analogue -- the Laegerdorf case

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koestler, A.G.; Reksten, K.

1995-09-01

Quantitative descriptions of 3D fracture networks in terms of fracture characteristics and connectivity are necessary for reservoir evaluation, management, and EOR programs of fractured reservoirs. The author`s research has focused on an analogue to North Sea fractured chalk reservoirs that is excellently exposed near Laegerdorf, northwest Germany. An underlying salt diapir uplifted and deformed Upper Cretaceous chalk; the cement industry now exploits it. The fracture network in the production wall of the quarry was characterized and mapped at different scales, and 12 profiles of the 230-m wide and 35-m high production wall were investigated as the wall receded 25 m.more » In addition, three wells were drilled into the chalk volume. The wells were cored and the wellbores were imaged with both the resistivity formation micro scanner (FMS) and the sonic circumferential borehole image logger (CBIL). The large amount of fracture data was analyzed with respect to parameters, such as fracture density distribution, orientation, and length distribution, and in terms of the representativity and predictability of data sets collected from restricted rock volumes.« less

Using well casing as an electrical source to monitor hydraulic fracture fluid injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilt, Michael; Nieuwenhuis, Greg; MacLennan, Kris

2016-03-09

The depth to surface resistivity (DSR) method transmits current from a source located in a cased or openhole well to a distant surface return electrode while electric field measurements are made at the surface over the target of interest. This paper presents both numerical modelling results and measured data from a hydraulic fracturing field test where conductive water was injected into a resistive shale reservoir during a hydraulic fracturing operation. Modelling experiments show that anomalies due to hydraulic fracturing are small but measureable with highly sensitive sensor technology. The field measurements confirm the model results,showing that measured differences in themore » surface fields due to hydraulic fracturing have been detected above the noise floor. Our results show that the DSR method is sensitive to the injection of frac fluids; they are detectable above the noise floor in a commercially active hydraulic fracturing operation, and therefore this method can be used for monitoring fracture fluid movement.« less

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

DOE PAGES

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.; ...

2017-08-19

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy’s Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models weremore » created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within ~40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90–130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.« less

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

NASA Astrophysics Data System (ADS)

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.; Swanson, Erika M.; Cooley, James A.

2017-08-01

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy's Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models were created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within 40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90-130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy’s Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models weremore » created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within ~40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90–130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christopher Liner

The objective of our work is graduate and undergraduate student training related to improved 3D seismic technology that addresses key challenges related to monitoring movement and containment of CO{sub 2}, specifically better quantification and sensitivity for mapping of caprock integrity, fractures, and other potential leakage pathways. We utilize data and results developed through previous DOE-funded CO{sub 2} characterization project (DE-FG26-06NT42734) at the Dickman Field of Ness County, KS. Dickman is a type locality for the geology that will be encountered for CO{sub 2} sequestration projects from northern Oklahoma across the U.S. midcontinent to Indiana and Illinois. Since its discovery inmore » 1962, the Dickman Field has produced about 1.7 million barrels of oil from porous Mississippian carbonates with a small structural closure at about 4400 ft drilling depth. Project data includes 3.3 square miles of 3D seismic data, 142 wells, with log, some core, and oil/water production data available. Only two wells penetrate the deep saline aquifer. In a previous DOE-funded project, geological and seismic data were integrated to create a geological property model and a flow simulation grid. We believe that sequestration of CO{sub 2} will largely occur in areas of relatively flat geology and simple near surface, similar to Dickman. The challenge is not complex geology, but development of improved, lower-cost methods for detecting natural fractures and subtle faults. Our project used numerical simulation to test methods of gathering multicomponent, full azimuth data ideal for this purpose. Our specific objectives were to apply advanced seismic methods to aide in quantifying reservoir properties and lateral continuity of CO{sub 2} sequestration targets. The purpose of the current project is graduate and undergraduate student training related to improved 3D seismic technology that addresses key challenges related to monitoring movement and containment of CO{sub 2}, specifically better quantification and sensitivity for mapping of caprock integrity, fractures, and other potential leakage pathways. Specifically, our focus is fundamental research on (1) innovative narrow-band seismic data decomposition and interpretation, and (2) numerical simulation of advanced seismic data (multi-component, high density, full azimuth data) ideal for mapping of cap rock integrity and potential leakage pathways.« less

3D characterization of the fracture network in a deformed chalk reservoir analogue: The Lagerdorf case

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koestler, A.G.; Reksten, K.

1994-12-31

Quantitative descriptions of the 3D fracture networks in terms of connectivity, fracture types, fracture surface roughness and flow characteristics are necessary for reservoir evaluation, management, and enhanced oil recovery programs of fractured reservoirs. For a period of 2 years, a research project focused on an analogue to fractured chalk reservoirs excellently exposed near Laegerdorf, NW Germany. Upper Cretaceous chalk has been uplifted and deformed by an underlying salt diapir, and is now exploited for the cement industry. In the production wall of a quarry, the fracture network of the deformed chalk was characterized and mapped at different scales. The wallmore » was scraped off as chalk exploitation proceeded, continuously revealing new sections through the faulted and fractured chalk body. A 230 m long part of the 35m high production wall was investigated during its recess of 25m. The large amount of fracture data were analyzed with respect to parameters such as fracture density distribution, orientation- and length distribution, and in terms of the representativity of data sets collected from restricted rock volumes. This 3D description and analysis of a fracture network revealed quantitative generic parameters of importance for modeling chalk reservoirs with less data and lower data quality.« less

Analysis of CFRP Joints by Means of T-Pull Mechanical Test and Ultrasonic Defects Detection.

PubMed

Casavola, Caterina; Palano, Fania; De Cillis, Francesco; Tati, Angelo; Terzi, Roberto; Luprano, Vincenza

2018-04-18

Defects detection within a composite component, with the aim of understanding and predicting its mechanical behavior, is of great importance in the aeronautical field because the irregularities of the composite material could compromise functionality. The aim of this paper is to detect defects by means of non-destructive testing (NDT) on T-pull samples made by carbon fiber reinforced polymers (CFRP) and to evaluate their effect on the mechanical response of the material. Samples, obtained from an industrial stringer having an inclined web and realized with a polymeric filler between cap and web, were subjected to ultrasonic monitoring and then to T-pull mechanical tests. All samples were tested with the same load mode and the same test configuration. An experimental set-up consisting of a semiautomatic C-scan ultrasonic mapping system with a phased array probe was designed and developed, optimizing control parameters and implementing image processing software. The present work is carried out on real composites parts that are characterized by having their intrinsic defectiveness, as opposed to the previous similar results in the literature mainly obtained on composite parts with artificially produced defects. In fact, although samples under study were realized free from defects, ultrasonic mapping found defectiveness inside the material. Moreover, the ultrasonic inspection could be useful in detecting both the location and size of defects. Experimental data were critically analyzed and qualitatively correlated with results of T-pull mechanical tests in order to better understand and explain mechanical behavior in terms of fracture mode.

Analysis of CFRP Joints by Means of T-Pull Mechanical Test and Ultrasonic Defects Detection

PubMed Central

Casavola, Caterina; Palano, Fania; De Cillis, Francesco; Tati, Angelo; Terzi, Roberto; Luprano, Vincenza

2018-01-01

Defects detection within a composite component, with the aim of understanding and predicting its mechanical behavior, is of great importance in the aeronautical field because the irregularities of the composite material could compromise functionality. The aim of this paper is to detect defects by means of non-destructive testing (NDT) on T-pull samples made by carbon fiber reinforced polymers (CFRP) and to evaluate their effect on the mechanical response of the material. Samples, obtained from an industrial stringer having an inclined web and realized with a polymeric filler between cap and web, were subjected to ultrasonic monitoring and then to T-pull mechanical tests. All samples were tested with the same load mode and the same test configuration. An experimental set-up consisting of a semiautomatic C-scan ultrasonic mapping system with a phased array probe was designed and developed, optimizing control parameters and implementing image processing software. The present work is carried out on real composites parts that are characterized by having their intrinsic defectiveness, as opposed to the previous similar results in the literature mainly obtained on composite parts with artificially produced defects. In fact, although samples under study were realized free from defects, ultrasonic mapping found defectiveness inside the material. Moreover, the ultrasonic inspection could be useful in detecting both the location and size of defects. Experimental data were critically analyzed and qualitatively correlated with results of T-pull mechanical tests in order to better understand and explain mechanical behavior in terms of fracture mode. PMID:29669992

Reliability of the pronator quadratus fat pad sign to predict the severity of distal radius fractures.

PubMed

Loesaus, Julia; Wobbe, Isabel; Stahlberg, Erik; Barkhausen, Joerg; Goltz, Jan Peter

2017-09-28

To evaluate the reliability of pronator quadratus fat pad sign to detect distal radius fracture and to predict its severity. Retrospectively we identified 89 consecutive patients (41 female, mean age 49 ± 18 years) who had X-ray (CR) and computed tomography (CT) within 24 h following distal forearm trauma. Thickness of pronator quadratus fat pad complex (PQC) was measured using lateral views (CR) and sagittal reconstructions (CT). Pearson's test was used to determine the correlation of the PQC thickness in CR and CT. A positive pronator quadratus sign (PQS) was defined as a PQC > 8.0 mm (female) or > 9.0 mm (male). Frykman classification was utilized to assess the severity of fractures. Forty-four/89 patients (49%) had a distal radius fracture (Frykman I n = 3, II n = 0, III n = 10, IV n = 5, V n = 2, VI n = 2, VII n = 9, VIII n = 13). Mean thickness of the PQC thickness can reliably be measured on X-ray views and was 7.5 ± 2.8 mm in lateral views (CR), respectively 9.4 ± 3.0 mm in sagittal reconstructions (CT), resulting in a significant correlation coefficient of 0.795. A positive PQS at CR was present in 21/44 patients (48%) with distal radius fracture and in 2/45 patients (4%) without distal radius fracture, resulting in a specificity of 96% and a sensitivity of 48% for the detection of distal radius fractures. There was no correlation between thickness of the PQC and severity of distal radius fractures. A positive PQS shows high specificity but low sensitivity for detection of distal radius fractures. The PQC thickness cannot predict the severity of distal radius fractures.

Reliability of the pronator quadratus fat pad sign to predict the severity of distal radius fractures

PubMed Central

Loesaus, Julia; Wobbe, Isabel; Stahlberg, Erik; Barkhausen, Joerg; Goltz, Jan Peter

2017-01-01

AIM To evaluate the reliability of pronator quadratus fat pad sign to detect distal radius fracture and to predict its severity. METHODS Retrospectively we identified 89 consecutive patients (41 female, mean age 49 ± 18 years) who had X-ray (CR) and computed tomography (CT) within 24 h following distal forearm trauma. Thickness of pronator quadratus fat pad complex (PQC) was measured using lateral views (CR) and sagittal reconstructions (CT). Pearson’s test was used to determine the correlation of the PQC thickness in CR and CT. A positive pronator quadratus sign (PQS) was defined as a PQC > 8.0 mm (female) or > 9.0 mm (male). Frykman classification was utilized to assess the severity of fractures. RESULTS Forty-four/89 patients (49%) had a distal radius fracture (Frykman I n = 3, II n = 0, III n = 10, IV n = 5, V n = 2, VI n = 2, VII n = 9, VIII n = 13). Mean thickness of the PQC thickness can reliably be measured on X-ray views and was 7.5 ± 2.8 mm in lateral views (CR), respectively 9.4 ± 3.0 mm in sagittal reconstructions (CT), resulting in a significant correlation coefficient of 0.795. A positive PQS at CR was present in 21/44 patients (48%) with distal radius fracture and in 2/45 patients (4%) without distal radius fracture, resulting in a specificity of 96% and a sensitivity of 48% for the detection of distal radius fractures. There was no correlation between thickness of the PQC and severity of distal radius fractures. CONCLUSION A positive PQS shows high specificity but low sensitivity for detection of distal radius fractures. The PQC thickness cannot predict the severity of distal radius fractures. PMID:29098069

Practical use of bone scan in patients with an osteoporotic vertebral compression fracture.

PubMed

Jun, Deuk Soo; An, Byoung Keun; Yu, Chang Hun; Hwang, Kyung Hoon; Paik, Je Won

2015-02-01

Rib fractures are one of main causes of chest or flank pain when related to an osteoporotic vertebral compression fracture (OVCF). The authors investigated the incidence and risk factors of rib fracture in 284 patients with OVCF using bone scans and evaluated the feasibility as to whether bone scans could be utilized as a useful screening tool. Hot uptake lesions on ribs were found in 122 cases (43.0%). The factors analyzed were age, sex, number and locations of fractured vertebrae, BMD, and compression rates as determined using initial radiography. However, no statistical significances were found. In 16 cases (5.6%), there were concurrent multiple fractures of both the thoracic and lumbar spines not detected by single site MRI. Sixty cases (21.1%) of OVCF with the a compression rate of less than 15% could not be identified definitely by initial plain radiography, but were confirmed by bone scans. It is concluded that a bone scan has outstanding ability for the screening of rib fractures associated with OVCF. Non-adjacent multiple fractures in both thoracic and lumbar spines and fractures not identified definitely by plain radiography were detected on bone scans, which provided a means for determining management strategies and predicting prognosis.

Evaluation of permeable fractures in rock aquifers

NASA Astrophysics Data System (ADS)

Bok Lee, Hang

2015-04-01

In this study, the practical usefulness and fundamental applicability of a self-potential (SP) method for identifying the permeable fractures were evaluated by a comparison of SP methods with other geophysical logging methods and hydraulic tests. At a 10 m-shallow borehole in the study site, the candidates of permeable fractures crossing the borehole were first determined by conventional geophysical methods such as an acoustic borehole televiwer, temperature, electrical conductivity and gamma-gamma loggings, which was compared to the analysis by the SP method. Constant pressure injection and recovery tests were conducted for verification of the hydraulic properties of the fractures identified by various logging methods. The acoustic borehole televiwer and gamma-gamma loggings detected the open space or weathering zone within the borehole, but they cannot prove the possibility of a groundwater flow through the detected fractures. The temperature and electrical conductivity loggings had limitations to detect the fractured zones where groundwater in the borehole flows out to the surrounding rock aquifers. Comparison of results from different methods showed that there is a best correlation between the distribution of hydraulic conductivity and the variation of the SP signals, and the SP logging can estimate accurately the hydraulic activity as well as the location of permeable fractures. Based on the results, the SP method is recommended for determining the hydraulically-active fractures rather than other conventional geophysical loggings. This self-potential method can be effectively applied in the initial stage of a site investigation which selects the optimal location and evaluates the hydrogeological property of fractures in target sites for the underground structure including the geothermal reservoir and radioactive waste disposal.

Aquifers survey in the context of source rocks exploitation: from baseline acquisition to long term monitoring

NASA Astrophysics Data System (ADS)

Garcia, Bruno; Rouchon, Virgile; Deflandre, Jean-Pierre

2017-04-01

Producing hydrocarbons from source rocks (like shales: a mix of clays, silts, carbonate and sandstone minerals containing matured organic matter, i.e. kerogen oil and gas, but also non-hydrocarbon various species of chemical elements including sometimes radioactive elements) requires to create permeability within the rock matrix by at least hydraulically fracturing the source rock. It corresponds to the production of hydrocarbon fuels that have not been naturally expelled from the pressurized matured source rock and that remain trapped in the porosity or/and kerogen porosity of the impermeable matrix. Azimuth and extent of developed fractures can be respectively determined and mapped by monitoring the associated induced microseismicity. This allows to have an idea of where and how far injected fluids penetrated the rock formation. In a geological context, aquifers are always present in the vicinity -or on fluid migration paths- of such shale formations: deep aquifers (near the shale formation) up to sub-surface and potable (surface) aquifers. Our purpose will be to track any unsuitable invasion or migration of chemicals specifies coming from matured shales of production fluids including both drilling and fracturing ones into aquifers. Our objective is to early detect and alarm of any anomaly to avoid any important environmental issue. The approach consists in deploying a specific sampling tool within a well to recover formation fluids and to run a panoply of appropriate laboratory tests to state on fluid characteristics. Of course for deep aquifers, such a characterization process may consider aquifer properties prior producing shale oil and gas, as they may contain naturally some chemical species present in the source rocks. One can also consider that a baseline acquisition could be justified in case of possible previous invasion of non-natural fluids in the formation under survey (due to any anthropogenic action at surface or in the underground). The paper aims at presenting the protocol and routine test we propose to make our early detection approach efficient for production of shale hydrocarbon fluids, in considering the source-rock reservoir itself, the aquifers, and also the chemical species present in the fluids that are used for hydraulic fracturing operations.

Is intramedullary nailing applicable for distal tibial fractures with ankle joint extension?

PubMed

Beytemür, Ozan; Albay, Cem; Adanır, Oktay; Yüksel, Serdar; Güleç, Mehmet Akif

2016-12-01

This study aims to evaluate the functional and radiographic results and treatment complications of AO/OTA (Arbeitsgemeinschaft fur Osteosynthesefragen/Orthopaedic Trauma Association) type 43C1 and C2 fractures treated with intramedullary nailing. We retrospectively evaluated 35 AO/OTA type 43C1 and C2 patients (26 males, 9 females; mean age 39.8±16.9 years; range 19 to 82 years) treated with intramedullary nailing. Two interfragmentary screws out of nail were applied in 10 patients (29%), while one interfragmentary screw out of nail was applied in 17 patients (49%). Intramedullary nailing was applied in eight patients (23%) without external screws. Fracture union, union time, alignment problems, and complications were evaluated. Clinical evaluation of patients was conducted using the Olerud and Molander score and by measuring the ankle joint range of motion. Union was achieved in all 35 patients. Mean union time was 16.5±2.8 weeks (range 12 to 24 weeks) and mean Olerud and Molander score was 88±8.24. Varus deformity was detected in one patient, valgus deformity was detected in two patients, and rotation deformity was detected in one patient. Superficial infection was detected in three patients (9%). Deep infection was not detected in any patient. Intramedullary nailing is not contraindicated for simple intra-articular distal tibial fractures. In these fractures, intramedullary nailing performed in accordance with its technique, with an additional percutaneous screw if necessary, is a successful treatment option with high fracture union rates, high functional results, and low complication rates.

The stream net as an indicator of cryptic systematic fracturing in Louisiana

USGS Publications Warehouse

McCulloh, R.P.

2003-01-01

The stream net in many parts of Louisiana includes straight reaches with preferred alignment in a few directions, with some examples spanning tens of kilometers. In places the reaches form classic rectangular drainage patterns. These characteristics are obvious on maps at a variety of scales, and are recognizable on some portion of nearly every 7.5-minute quadrangle in the state, excepting those quadrangles situated entirely within the Ho??ocene coastal marshes or the Holocene flood plains of the larger rivers. Such patterns of lineaments are reminiscent of patterns associated with systematic fracturing in other regions. In Louisiana, however, verification and measurement of fractures that may exist in the vicinity of rectilinear drainage anomalies is problematic because surface deposits are comparatively young and sparsely exposed, and tend, especially near waterways, to be heavily weathered and vegetated. An indirect approach to evaluating the potential influence on drainage by fracturing involves evaluating the frequency distribution of stream-course orientations based on its degree of similarity with that of the strikes of previously mapped or reported fractures (faults and/or joints). A rose diagram of orientation frequencies for the stream net of the entire state, created utilizing a publicly available line dataset processed into 100-m segments (N 290,000), shows a nonrandom distribution with three visually identifiable trends: the strongest, oriented essentially N-S; a subsidiary trend oriented N20??-30??W; and a weak trend oriented N80??-90??W. The entire population of orientations yields a mean direction of N17.5??W ?? 4.2?? with a probability of 95 percent. The strike frequencies of mapped faults show little correspondence with these trends. This suggests, if mapped faults are at least representative of actual faults, that insofar as apparent lineaments reflect structure and not the influence of a south-southeasterly regional drainage gradient, they predominantly reveal the influence of joints. These could reflect either a Quaternary stress regime, or propagation in young sediment of a structural pattern in underlying older strata. The data available at present do not compel either interpretation, though in south Louisiana at least, where reactivated early Tertiary growth faults have surface expression that in places is juxtaposed with differently oriented drainage lineaments, propagation of a preexisting pattern from depth appears plausible. Widespread systematic fracturing in this predominantly Quaternary coastal-plain setting could have important implications for groundwater flow and for other processes that depend substantially on permeability.

An approximate solution for a penny-shaped hydraulic fracture that accounts for fracture toughness, fluid viscosity and leak-off.

PubMed

Dontsov, E V

2016-12-01

This paper develops a closed-form approximate solution for a penny-shaped hydraulic fracture whose behaviour is determined by an interplay of three competing physical processes that are associated with fluid viscosity, fracture toughness and fluid leak-off. The primary assumption that permits one to construct the solution is that the fracture behaviour is mainly determined by the three-process multiscale tip asymptotics and the global fluid volume balance. First, the developed approximation is compared with the existing solutions for all limiting regimes of propagation. Then, a solution map, which indicates applicability regions of the limiting solutions, is constructed. It is also shown that the constructed approximation accurately captures the scaling that is associated with the transition from any one limiting solution to another. The developed approximation is tested against a reference numerical solution, showing that accuracy of the fracture width and radius predictions lie within a fraction of a per cent for a wide range of parameters. As a result, the constructed approximation provides a rapid solution for a penny-shaped hydraulic fracture, which can be used for quick fracture design calculations or as a reference solution to evaluate accuracy of various hydraulic fracture simulators.

An approximate solution for a penny-shaped hydraulic fracture that accounts for fracture toughness, fluid viscosity and leak-off

NASA Astrophysics Data System (ADS)

Dontsov, E. V.

2016-12-01

This paper develops a closed-form approximate solution for a penny-shaped hydraulic fracture whose behaviour is determined by an interplay of three competing physical processes that are associated with fluid viscosity, fracture toughness and fluid leak-off. The primary assumption that permits one to construct the solution is that the fracture behaviour is mainly determined by the three-process multiscale tip asymptotics and the global fluid volume balance. First, the developed approximation is compared with the existing solutions for all limiting regimes of propagation. Then, a solution map, which indicates applicability regions of the limiting solutions, is constructed. It is also shown that the constructed approximation accurately captures the scaling that is associated with the transition from any one limiting solution to another. The developed approximation is tested against a reference numerical solution, showing that accuracy of the fracture width and radius predictions lie within a fraction of a per cent for a wide range of parameters. As a result, the constructed approximation provides a rapid solution for a penny-shaped hydraulic fracture, which can be used for quick fracture design calculations or as a reference solution to evaluate accuracy of various hydraulic fracture simulators.

TDEM survey in an area of seismicity induced by water wells in Paraná sedimentary basin, Northern São Paulo State, Brazil

NASA Astrophysics Data System (ADS)

Porsani, Jorge Luís; Almeida, Emerson Rodrigo; Bortolozo, Cassiano Antonio; Santos, Fernando Acácio Monteiro dos

2012-07-01

This article presents TDEM results from an area with recent induced shallow seismicity. The purpose was to do a geoelectrical mapping of sedimentary and fractured basaltic aquifers for better understanding of the hydrogeologic setting. The study area is in the Paraná basin where flood basalts are overlain by sedimentary units near the city of Bebedouro, northern São Paulo State, Brazil. 86 TDEM soundings were acquired in an area of 90 km2 in the Andes and Botafogo study areas. The soundings were chosen next to wells for calibration, and also along profiles crossing the seismically active areas. 1-D interpretation results showed the general geoelectrical stratigraphy of this part of the Paraná basin. The upper geoelectrical layer is the shallow sedimentary aquifer (Adamantina formation) with less than 80 m thickness. The second geoelectrical layer contains the upper basalts of the Serra Geral formation at about 60-80 m depths. A saturated fractured basalt zone between 100 and 300 m depths was identifiable on various TDEM soundings. This depth range corresponds to the range of hypocentral depths for more than 3000 micro-earthquakes in this area. The lower basalt layer was estimated to lie between 400 and 650 m depth. The deepest geoelectrical layer detected by various TDEM soundings corresponds to the Botucatu sandstone (Guarani aquifer). Results suggest that the high-discharge wells are located in the fractured zone in the middle basalt of the Serra Geral formation. There is a good correlation between seismically active areas, high discharge wells (> 190 m3/h), and fracture zones in the middle basalt. The results reinforce the hypothesis that the shallow seismic activity in the Bebedouro region is being triggered by high rates of groundwater withdrawal.

Encapsulated microenergetic material

DOEpatents

Roberts, Jeffery James; Aines, Roger D.; Duoss, Eric B.; Spadaccini, Christopher M.; Vandersall, Kevin S.

2018-02-20

Providing high energy materials that can be placed in previously created fractures and activating them in place to extend or change an existing fracture system. Also detecting the location of fractures or permeable pathways and a means to assess the extent and efficiency of proppant emplacement.

Encapsulated microenergetic material

DOEpatents

Roberts, Jeffery James; Aines, Roger D.; Duoss, Eric B.; Spadaccini, Christopher M.; Vandersall, Kevin S.

2017-02-07

Providing high energy materials that can be placed in previously created fractures and activating them in place to extend or change an existing fracture system. Also detecting the location of fractures or permeable pathways and a means to assess the extent and efficiency of proppant emplacement.

INNOVATIVE METHODOLOGY FOR DETECTION OF FRACTURE-CONTROLLED SWEET SPOTS IN THE NORTHERN APPALACHIAN BASIN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert Jacobi; John Fountain

2002-01-30

In the structure task, we completed reducing the data we had collected from a N-S transect on the east of Seneca Lake. We have calculated the fracture frequency for all the fracture sets at each site, and constructed modified rose diagrams that summarize the fracture attributes at each site. These data indicate a N-striking fault near the southeastern shore of Seneca Lake, and also indicate NE and ENE-trending FIDs and faults north of Valois. The orientation and existence of the ENE-striking FIDs and faults are thought to be guided by faults in the Precambrian basement; these basement faults apparently weremore » sufficiently reactivated to cause faulting in the Paleozoic section. Other faults are thrust ramps above the Silurian salt section that were controlled by a far-field Alleghanian stress field. Structure contour maps and isopach maps have been revised based on additional well log analyses. Except for the Glodes Corners Field, the well spacing generally is insufficient to definitively identify faults. However, relatively sharp elevational changes east of Keuka Lake support the contention that faults occur along the east side of Keuka Lake. Outcrop stratigraphy along the east side of Seneca Lake indicates that faults and gentle folds can be inferred from the some exposures along Seneca Lake, but the lensing nature of the individual sandstones can preclude long-distance definitive correlations and structure identification. Soil gas data collected during the 2000 field season was reduced and displayed in the previous semiannual report. The seismic data that Quest licensed has been reprocessed. Several grabens observed in the Trenton reflector are consistent with surface structure, soil gas, and aeromagnetic anomalies. In this report we display an interpreted seismic line that crosses the Glodes Corners and Muck Farm fields. The final report from the subcontractor concerning the completed aeromagnetic survey is included. Prominent magnetic anomalies suggest that faults in the Precambrian basement are located beneath regions where grabens in the Trenton are located. The trend and location of these faults based on aeromagnetics agrees with the location based on FIDs. These data indicate that integration of aeromagnetic and topographic lineaments, surface structure, soil gas with seismic and well logs allows us to extrapolate Trenton-Black River trends away from confirmatory seismic lines.« less

Evaluation of the Location and Recency of Faulting Near Prospective Surface Facilities in Midway Valley, Nye County, Nevada

USGS Publications Warehouse

Swan, F.H.; Wesling, J.R.; Angell, M.M.; Thomas, A.P.; Whitney, J.W.; Gibson, J.D.

2001-01-01

Evaluation of surface faulting that may pose a hazard to prospective surface facilities is an important element of the tectonic studies for the potential Yucca Mountain high-level radioactive waste repository in southwestern Nevada. For this purpose, a program of detailed geologic mapping and trenching was done to obtain surface and near-surface geologic data that are essential for determining the location and recency of faults at a prospective surface-facilities site located east of Exile Hill in Midway Valley, near the eastern base of Yucca Mountain. The dominant tectonic features in the Midway Valley area are the north- to northeast-trending, west-dipping normal faults that bound the Midway Valley structural block-the Bow Ridge fault on the west side of Exile Hill and the Paint-brush Canyon fault on the east side of the valley. Trenching of Quaternary sediments has exposed evidence of displacements, which demonstrate that these block-bounding faults repeatedly ruptured the surface during the middle to late Quaternary. Geologic mapping, subsurface borehole and geophysical data, and the results of trenching activities indicate the presence of north- to northeast-trending faults and northwest-trending faults in Tertiary volcanic rocks beneath alluvial and colluvial sediments near the prospective surface-facilities site. North to northeast-trending faults include the Exile Hill fault along the eastern base of Exile Hill and faults to the east beneath the surficial deposits of Midway Valley. These faults have no geomorphic expression, but two north- to northeast-trending zones of fractures exposed in excavated profiles of middle to late Pleistocene deposits at the prospective surface-facilities site appear to be associated with these faults. Northwest-trending faults include the West Portal and East Portal faults, but no disruption of Quaternary deposits by these faults is evident. The western zone of fractures is associated with the Exile Hill fault. The eastern zone of fractures is within Quaternary alluvial sediments, but no bedrock was encountered in trenches and soil pits in this part of the prospective surface facilities site; thus, the direct association of this zone with one or more bedrock faults is uncertain. No displacement of lithologic contacts and soil horizons could be detected in the fractured Quaternary deposits. The results of these investigations imply the absence of any appreciable late Quaternary faulting activity at the prospective surface-facilities site.

Gear Crack Propagation Path Studies: Guidelines for Ultra-Safe Design

NASA Technical Reports Server (NTRS)

Lewicki, David G.

2001-01-01

Design guidelines have been established to prevent catastrophic rim fracture failure modes when considering gear tooth bending fatigue. Analysis was performed using the finite element method with principles of linear elastic fracture mechanics. Crack propagation paths were predicted for a variety of gear tooth and rim configurations. The effects of rim and web thicknesses, initial crack locations, and gear tooth geometry factors such as diametral pitch, number of teeth, pitch radius, and tooth pressure angle were considered. Design maps of tooth/rim fracture modes including effects of gear geometry, applied load, crack size, and material properties were developed. The occurrence of rim fractures significantly increased as the backup ratio (rim thickness divided by tooth height) decreased. The occurrence of rim fractures also increased as the initial crack location was moved down the root of the tooth. Increased rim and web compliance increased the occurrence of rim fractures. For gears with constant pitch radii, coarser-pitch teeth increased the occurrence of tooth fractures over rim fractures. Also, 25 deg pressure angle teeth had an increased occurrence of tooth fractures over rim fractures when compared to 20 deg pressure angle teeth. For gears with constant number of teeth or gears with constant diametral pitch, varying size had little or no effect on crack propagation paths.

High-speed polarized light microscopy for in situ, dynamic measurement of birefringence properties

NASA Astrophysics Data System (ADS)

Wu, Xianyu; Pankow, Mark; Shadow Huang, Hsiao-Ying; Peters, Kara

2018-01-01

A high-speed, quantitative polarized light microscopy (QPLM) instrument has been developed to monitor the optical slow axis spatial realignment during controlled medium to high strain rate experiments at acquisition rates up to 10 kHz. This high-speed QPLM instrument is implemented within a modified drop tower and demonstrated using polycarbonate specimens. By utilizing a rotating quarter wave plate and a high-speed camera, the minimum acquisition time to generate an alignment map of a birefringent specimen is 6.1 ms. A sequential analysis method allows the QPLM instrument to generate QPLM data at the high-speed camera imaging frequency 10 kHz. The obtained QPLM data is processed using a vector correlation technique to detect anomalous optical axis realignment and retardation changes throughout the loading event. The detected anomalous optical axis realignment is shown to be associated with crack initiation, propagation, and specimen failure in a dynamically loaded polycarbonate specimen. The work provides a foundation for detecting damage in biological tissues through local collagen fiber realignment and fracture during dynamic loading.

Delineating the Rattlesnake Springs, New Mexico Watershed Using Precision Gravity Techniques

NASA Astrophysics Data System (ADS)

Doser, D. I.; Boykov, N. D.; Baker, M. R.; Kaip, G. M.; Langford, R. P.

2009-12-01

Rattlesnake Springs serves as the sole domestic water source for Carlsbad Caverns National Park. The recent development of oil and gas leases and agricultural lands surrounding the springs has led to concern about contamination of the fracture controlled aquifer system. We have conducted a series of precision gravity surveys (station spacing 200 to 300 m in a 4 x 4 km area), combined with other geophysical studies and geologic mapping, to delineate possible fracture systems in the gypsum and carbonate bedrock that feed the spring system. Our combined results suggest several pathways for water to enter the springs. A series of WNW-ESE striking features are apparent in our gravity data that appear to align with relict spring valleys we have mapped to the west of the springs. A self potential survey indicates that water is entering the springs at a shallow level from the northwest direction. However, gravity data also indicate a north-south trending fracture system could be providing a pathway for water to enter from the south. This is consistent with drawdown tests conducted in the 1950’s and 1960’s on irrigation wells located to the south of the springs. The north-south fracture system appears related to a basin bounding fault system observed in the regional gravity data.

Development of an Ultrasonic Phased Array System for Wellbore Integrity Evaluation and Near-Wellbore Fracture Network Mapping of Injection and Production Wells in Geothermal Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almansouri, Hani; Foster, Benjamin; Kisner, Roger A

2016-01-01

This paper documents our progress developing an ultrasound phased array system in combination with a model-based iterative reconstruction (MBIR) algorithm to inspect the health of and characterize the composition of the near-wellbore region for geothermal reservoirs. The main goal for this system is to provide a near-wellbore in-situ characterization capability that will significantly improve wellbore integrity evaluation and near well-bore fracture network mapping. A more detailed image of the fracture network near the wellbore in particular will enable the selection of optimal locations for stimulation along the wellbore, provide critical data that can be used to improve stimulation design, andmore » provide a means for measuring evolution of the fracture network to support long term management of reservoir operations. Development of such a measurement capability supports current hydrothermal operations as well as the successful demonstration of Engineered Geothermal Systems (EGS). The paper will include the design of the phased array system, the performance specifications, and characterization methodology. In addition, we will describe the MBIR forward model derived for the phased array system and the propagation of compressional waves through a pseudo-homogenous medium.« less

Early diagnosis of thoracolumbar spine fractures in children. A prospective study.

PubMed

Leroux, J; Vivier, P-H; Ould Slimane, M; Foulongne, E; Abu-Amara, S; Lechevallier, J; Griffet, J

2013-02-01

Early detection of spine fractures in children is difficult because the clinical examination does not always raise worrisome symptoms and the vertebrae are still cartilaginous, and consequently incompletely visualized on routine X-rays. Therefore, diagnosis is often delayed or missed. The search for a "breath arrest" sensation at the moment of the trauma improves early detection of thoracolumbar spine fractures in children. This was a prospective monocentric study including all children consulting at the paediatric emergency unit of a single university hospital with a thoracolumbar spine trauma between January 2008 and March 2009. All children had the same care. Pain was quantified when they arrived using the visual analog scale. Clinical examination searched for a "breath arrest" sensation at the moment of the trauma and noted the circumstances of the accident. X-rays and MRI were done in all cases. Fifty children were included with a mean age of 11.4 years. Trauma occurred during games or sports in 94% of the cases. They fell on the back in 72% cases. Twenty-three children (46%) had fractures on the MRI, with a mean number of four fractured vertebrae (range, 1-10). Twenty-one of them (91%) had a "breath arrest" sensation. Fractures were not visualized on X-rays in five cases (22%). Twenty-seven children had no fracture; 19 of them (70%) did not feel a "breath arrest". Fractures were suspected on X-rays in 15 cases (56%). The search for a "breath arrest" sensation at the moment of injury improves early detection of thoracolumbar spine fractures in children (Se=87%, Sp=67%, PPV=69%, NPV=86%). When no fracture is apparent on X-rays and no "breath arrest" sensation is expressed by the child, the clinician can be sure there is no fracture (Se=26%, Sp=100%, PPV=100%, NPV=53%). Level III. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Use of whole body CT to detect patterns of CPR-related injuries after sudden cardiac arrest.

PubMed

Dunham, Gregor M; Perez-Girbes, Alexandre; Bolster, Ferdia; Sheehan, Kellie; Linnau, Ken F

2017-11-09

We have recently implemented a dedicated sudden cardiac arrest (SCA) - whole-body computed tomography (WBCT) protocol to evaluate SCA patients with return of spontaneous circulation (ROSC) following cardiopulmonary resuscitation (CPR). The aim of this study is to evaluate the number and pattern of CPR-related injuries in ROSC patients with SCA-WBCT. Single-centre retrospective review of 39 patients (13 female; 20 male, mean age 51.8 years) with non-traumatic, out-of-hospital SCA and ROSC and evaluation with dedicated SCA-WBCT over a 10-month period. In-hospital mortality was 54%. CPR-related injuries were detected in 85% (33/39). Chest injuries were most common on WBCT: 85% (33) subjects had rib fractures (mean of 8.5 fractures/subject); 31% (12) sternal fractures; 13% (5) mediastinal haematoma; 10% (4) pneumothorax; 8% (3) pneumomediastinum and 3% (1) haemothorax. Three subjects (8%) had abdominal injuries on WBCT, including one hepatic haematoma with active haemorrhage. CPR-related injuries on WBCT after ROSC are common, with serial rib fractures detected most commonly. An unexpectedly high rate of abdominal injuries was detected on SCA-WBCT. Radiologists need to be attuned to the spectrum of CPR-related injuries in WBCT, including abdominal injuries and subtle rib fractures. • CPR frequently causes injuries. • Radiologists should be aware of the spectrum of CPR related injuries. • Rib fractures are frequent and radiologic findings often subtle. • Clinically unexpected abdominal injuries may be present.

Regional fracture patterns around volcanoes: Possible evidence for volcanic spreading on Venus

NASA Astrophysics Data System (ADS)

López, I.; Lillo, J.; Hansen, V. L.

2008-06-01

Magellan data show that the surface of Venus is dominated by volcanic landforms including large flow fields and a wide range of volcanic edifices that occur in different magmatic and tectonic environments. This study presents the results from a comprehensive survey of volcano-rift interaction in the BAT region and its surroundings. We carried out structural mapping of examples where interaction between volcanoes and regional fractures results in a deflection of the fractures around the volcanic features and discuss the nature of the local volcano-related stress fields that might be responsible for the observed variations of the regional fracture systems. We propose that the deflection of the regional fractures around these venusian volcanoes might be related to volcanic spreading, a process recognized as of great importance in the tectonic evolution of volcanoes on Earth and Mars, but not previously described on Venus.

Tectonic analysis of folds in the Colorado plateau of Arizona

NASA Technical Reports Server (NTRS)

Davis, G. H.

1975-01-01

Structural mapping and analysis of folds in Phanerozoic rocks in northern Arizona, using LANDSAT-1 imagery, yielded information for a tectonic model useful in identifying regional fracture zones within the Colorado Plateau tectonic province. Since the monoclines within the province developed as a response to differential movements of basement blocks along high-angle faults, the monoclinal fold pattern records the position and trend of many elements of the regional fracture system. The Plateau is divided into a mosaic of complex, polyhedral crustal blocks whose steeply dipping faces correspond to major fracture zones. Zones of convergence and changes in the trend of the monoclinal traces reveal the corners of the blocks. Igneous (and salt) diapirs have been emplaced into many of the designated zones of crustal weakness. As loci of major fracturing, folding, and probably facies changes, the fractures exert control on the entrapment of oil and gas.

Mechanistic Study of Delamination Fracture in Al-Li Alloy C458 (2099)

NASA Technical Reports Server (NTRS)

Tayon, W. A.; Crooks, R. E.; Domack, M. S.; Wagner, J. A.; Beaudoin, A. J.; McDonald, R. J.

2009-01-01

Delamination fracture has limited the use of lightweight Al-Li alloys. In the present study, electron backscattered diffraction (EBSD) methods were used to characterize crack paths in Al-Li alloy C458 (2099). Secondary delamination cracks in fracture toughness samples showed a pronounced tendency for fracture between grain variants of the same deformation texture component. These results were analyzed by EBSD mapping methods and simulated with finite element analyses. Simulation procedures include a description of material anisotropy, local grain orientations, and fracture utilizing crystal plasticity and cohesive zone elements. Taylor factors computed for each grain orientation subjected to normal and shear stresses indicated that grain pairs with the largest Taylor factor differences were adjacent to boundaries that failed by delamination. Examination of matching delamination fracture surface pairs revealed pronounced slip bands in only one of the grains bordering the delamination. These results, along with EBSD studies, plasticity simulations, and Auger electron spectroscopy observations support a hypothesis that delamination fracture occurs due to poor slip accommodation along boundaries between grains with greatly differing plastic response.

Bone tissue heterogeneity is associated with fracture toughness: a polarization Raman spectroscopy study

NASA Astrophysics Data System (ADS)

Makowski, Alexander J.; Granke, Mathilde; Uppuganti, Sasidhar; Mahadevan-Jansen, Anita; Nyman, Jeffry S.

2015-02-01

Polarization Raman Spectroscopy has been used to demonstrate microstructural features and collagen fiber orientation in human and mouse bone, concurrently measuring both organization and composition; however, it is unclear as to what extent these measurements explain the mechanical quality of bone. In a cohort of age and gender matched cadaveric cortical bone samples (23-101 yr.), we show homogeneity of both composition and structure are associated with the age related decrease in fracture toughness. 64 samples were machined into uniform specimens and notched for mechanical fracture toughness testing and polished for Raman Spectroscopy. Fingerprint region spectra were acquired on wet bone prior to mechanical testing by sampling nine different microstructural features spaced in a 750x750 μm grid in the region of intended crack propagation. After ASTM E1820 single edge notched beam fracture toughness tests, the sample was dried in ethanol and the osteonal-interstitial border of one osteon was samples in a 32x32 grid of 2μm2 pixels for two orthogonal orientations relative to the long bone axis. Standard peak ratios from the 9 separate microstructures show heterogeneity between structures but do not sufficiently explain fracture toughness; however, peak ratios from mapping highlight both lamellar contrast (ν1Phos/Amide I) and osteon-interstitial contrast (ν1Phos/Proline). Combining registered orthogonal maps allowed for multivariate analysis of underlying biochemical signatures. Image entropy and homogeneity metrics of single principal components significantly explain resistance to crack initiation and propagation. Ultimately, a combination of polarization content and multivariate Raman signatures allowed for the association of microstructural tissue heterogeneity with fracture resistance.

Aromatase Inhibitor-Associated Bone Fractures: A Case-Cohort GWAS and Functional Genomics

PubMed Central

Liu, Mohan; Goss, Paul E.; Ingle, James N.; Kubo, Michiaki; Furukawa, Yoichi; Batzler, Anthony; Jenkins, Gregory D.; Carlson, Erin E.; Nakamura, Yusuke; Schaid, Daniel J.; Chapman, Judy-Anne W.; Shepherd, Lois E.; Ellis, Matthew J.; Khosla, Sundeep; Wang, Liewei

2014-01-01

Bone fractures are a major consequence of osteoporosis. There is a direct relationship between serum estrogen concentrations and osteoporosis risk. Aromatase inhibitors (AIs) greatly decrease serum estrogen levels in postmenopausal women, and increased incidence of fractures is a side effect of AI therapy. We performed a discovery case-cohort genome-wide association study (GWAS) using samples from 1071 patients, 231 cases and 840 controls, enrolled in the MA.27 breast cancer AI trial to identify genetic factors involved in AI-related fractures, followed by functional genomic validation. Association analyses identified 20 GWAS single nucleotide polymorphism (SNP) signals with P < 5E-06. After removal of signals in gene deserts and those composed entirely of imputed SNPs, we applied a functional validation “decision cascade” that resulted in validation of the CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A, and MAP4K4 genes. These genes all displayed estradiol (E2)-dependent induction in human fetal osteoblasts transfected with estrogen receptor-α, and their knockdown altered the expression of known osteoporosis-related genes. These same genes also displayed SNP-dependent variation in E2 induction that paralleled the SNP-dependent induction of known osteoporosis genes, such as osteoprotegerin. In summary, our case-cohort GWAS identified SNPs in or near CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A, and MAP4K4 that were associated with risk for bone fracture in estrogen receptor-positive breast cancer patients treated with AIs. These genes displayed E2-dependent induction, their knockdown altered the expression of genes related to osteoporosis, and they displayed SNP genotype-dependent variation in E2 induction. These observations may lead to the identification of novel mechanisms associated with fracture risk in postmenopausal women treated with AIs. PMID:25148458

Sonic logging for detecting the excavation disturbed and fracture zones

NASA Astrophysics Data System (ADS)

Lin, Y. C.; Chang, Y. F.; Liu, J. W.; Tseng, C. W.

2017-12-01

This study presents a new sonic logging method to detect the excavation disturbed zone (EDZ) and fracture zones in a tunnel. The EDZ is a weak rock zone where its properties and conditions have been changed by excavation, which results such as fracturing, stress redistribution and desaturation in this zone. Thus, the EDZ is considered as a physically less stable and could form a continuous and high-permeable pathway for groundwater flow. Since EDZ and fracture zone have the potential of affecting the safety of the underground openings and repository performance, many studies were conducted to characterize the EDZ and fracture zone by different methods, such as the rock mass displacements and strain measurements, seismic refraction survey, seismic tomography and hydraulic test, etc. In this study, we designed a new sonic logging method to explore the EDZ and fracture zone in a tunnel at eastern Taiwan. A high power and high frequency sonic system was set up which includes a two hydrophones pitch-catch technique with a common-offset immersed in water-filled uncased wells and producing a 20 KHz sound to scan the well rock. Four dominant sonic events were observed in the measurements, they are refracted P- and S-wave along the well rock, direct water wave and the reverberation in the well water. Thus the measured P- and S-wave velocities, the signal-to-noise ratio of the refraction and the amplitudes of reverberation along the well rock were used as indexes to determine the EDZ and fracture zone. Comparing these indexes with core samples shows that significant changes in the indexes are consistent with the EDZ and fracture zone. Thus, the EDZ and fracture zone can be detected by this new sonic method conclusively.

Prevalence of silent vertebral fractures detected by vertebral fracture assessment in young Portuguese men with hyperthyroidism.

PubMed

Barbosa, Ana Paula; Rui Mascarenhas, Mário; Silva, Carlos Francisco; Távora, Isabel; Bicho, Manuel; do Carmo, Isabel; de Oliveira, António Gouveia

2015-02-01

Hyperthyroidism is a risk factor for reduced bone mineral density (BMD) and osteoporotic fractures. Vertebral fracture assessment (VFA) by dual-energy X-ray absorptiometry (DXA) is a radiological method of visualization of the spine, which enables patient comfort and reduced radiation exposure. This study was carried out to evaluate BMD and the prevalence of silent vertebral fractures in young men with hyperthyroidism. We conducted a cross-sectional study in a group of Portuguese men aged up to 50 years and matched in hyperthyroidism (n=24) and control (n=24) groups. A group of 48 Portuguese men aged up to 50 years was divided and matched in hyperthyroidism (n=24) and control (n=24) groups. BMD (g/cm(2)) at L1-L4, hip, radius 33%, and whole body as well as the total body masses (kg) were studied by DXA. VFA was used to detect fractures and those were classified by Genant's semiquantitative method. No patient had previously been treated for hyperthyroidism, osteoporosis, or low bone mass. Adequate statistical tests were used. The mean age, height, and total fat mass were similar in both groups (P≥0.05). The total lean body mass and the mean BMD at lumbar spine, hip, and whole body were significantly decreased in the hyperthyroidism group. In this group, there was also a trend for an increased prevalence of reduced BMD/osteoporosis and osteoporotic vertebral fractures. The results obtained using VFA technology (confirmed by X-ray) suggest that the BMD changes in young men with nontreated hyperthyroidism may lead to the development of osteoporosis and vertebral fractures. This supports the pertinence of using VFA in the routine of osteoporosis assessment to detect silent fractures precociously and consider early treatment. © 2015 European Society of Endocrinology.

Reappraisal of Pediatric Diastatic Skull Fractures in the 3-Dimensional CT Era: Clinical Characteristics and Comparison of Diagnostic Accuracy of Simple Skull X-Ray, 2-Dimensional CT, and 3-Dimensional CT.

PubMed

Sim, Sook Young; Kim, Hyun Gi; Yoon, Soo Han; Choi, Jong Wook; Cho, Sung Min; Choi, Mi Sun

2017-12-01

Diastatic skull fractures (DSFs) in children are difficult to detect in skull radiographs before they develop into growing skull fractures; therefore, little information is available on this topic. However, recent advances in 3-dimensional (3D) computed tomography (CT) imaging technology have enabled more accurate diagnoses of almost all forms of skull fracture. The present study was undertaken to document the clinical characteristics of DSFs in children and to determine whether 3D CT enhances diagnostic accuracy. Two hundred and ninety-two children younger than 12 years with skull fractures underwent simple skull radiography, 2-dimensional (2D) CT, and 3DCT. Results were compared with respect to fracture type, location, associated lesions, and accuracy of diagnosis. DSFs were diagnosed in 44 (15.7%) of children with skull fractures. Twenty-two patients had DSFs only, and the other 22 had DSFs combined with compound or mixed skull fractures. The most common fracture locations were the occipitomastoid (25%) and lambdoid (15.9%). Accompanying lesions consisted of subgaleal hemorrhages (42/44), epidural hemorrhages (32/44), pneumocephalus (17/44), and subdural hemorrhages (3/44). A total of 17 surgical procedures were performed on 15 of the 44 patients. Fourteen and 19 patients were confirmed to have DSFs by skull radiography and 2D CT, respectively, but 3D CT detected DSFs in 43 of the 44 children (P < 0.001). 3D CT was found to be markedly superior to skull radiography or 2D CT for detecting DSFs. This finding indicates that 3D CT should be used routinely rather than 2D CT for the assessment of pediatric head trauma. Copyright © 2017 Elsevier Inc. All rights reserved.

Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks

PubMed Central

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

2015-01-01

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable. PMID:26676058

Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks.

PubMed

Jordan, Amy B; Stauffer, Philip H; Knight, Earl E; Rougier, Esteban; Anderson, Dale N

2015-12-17

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.

Stress fractures of the ribs in elite competitive rowers: a report of nine cases.

PubMed

Dragoni, S; Giombini, A; Di Cesare, A; Ripani, M; Magliani, G

2007-10-01

The objective was to report the clinical and imaging patterns of nine cases of stress fractures of the rib diagnosed in Italian Olympic rowers. Nine patients with stress fractures of the rib detected from 103 (8.7%) Italian team rowers competing between May 2000 and May 2006 were identified based on the database of a sports medicine institute. All athletes were male. They were aged between 17 and 31 years (mean: 24.4). Patient weight, fracture location, rowing side and imaging methods employed were noted. The diagnosis was made based on history, clinical examination and Tc-99m MDP bone scintigraphy. Eight of the 9 fractures were located anterolaterally between the fourth and ninth rib. In 1 of the 5 athletes with standard radiographs, a fracture line was visible and in 4 there was callus formation. In 2 athletes sonography was performed, which detected discontinuity of the rib surface and callus formation (1 case each). Stress fractures of the ribs are relatively common in competitive rowers. They are characterized by increasing lateral chest pain and typical scintigraphic, radiographic and sonographic findings.

Vertical root fractures and their management

PubMed Central

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-01-01

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Characteristics of Rib Fractures in Child Abuse-The Role of Low-Dose Chest Computed Tomography.

PubMed

Sanchez, Thomas R; Grasparil, Angelo D; Chaudhari, Ruchir; Coulter, Kevin P; Wootton-Gorges, Sandra L

2018-02-01

Our aim is to describe the radiologic characteristics of rib fractures in clinically diagnosed cases of child abuse and suggest a complementary imaging for radiographically occult injuries in highly suspicious cases of child abuse. Retrospective analysis of initial and follow-up skeletal surveys and computed tomography (CT) scans of 16 patients younger than 12 months were reviewed after obtaining approval from our institutional review board. The number, location, displacement, and age of the rib fractures were recorded. Out of a total 105 rib fractures, 84% (87/105) were detected on the initial skeletal survey. Seventeen percent (18/105) were seen only after follow-up imaging, more than half of which (11/18) were detected on a subsequent CT. Majority of the fractures were posterior (43%) and anterior (30%) in location. An overwhelming majority (96%) of the fractures are nondisplaced. Seventeen percent of rib fractures analyzed in the study were not documented on the initial skeletal survey. Majority of fractures are nondisplaced and located posteriorly or anteriorly, areas that are often difficult to assess especially in the acute stage. The CT scan is more sensitive in evaluating these types of fractures. Low-dose chest CT can be an important imaging modality for suspicious cases of child abuse when initial radiographic findings are inconclusive.

Fatal carotid dissection after blunt head trauma.

PubMed

Tartara, F; Regolo, P; Servadei, F; Versari, P P; Giovanelli, M

2000-06-01

Occurrence of internal carotid artery injuries associated with skull base fracture has been reported. A. report a case of fatal intracranial carotid dissection related to petrous fracture involving the carotid canal. Identification of carotid lesions may be difficult and generally related to appearance of unexpected neurological deficit. Skull base fractures may be considered an indirect sign for detection of vascular injury. Patterns of the fracture are of paramount importance; routine CT scan may fail to detect basilar fractures and high definition fine-cut CT scan should be executed to carefully identify and evaluate fractures. Temporal and sphenoid bone fractures are common in head trauma and involvement of the course of the carotid artery is frequent. The involvement of the intracranial carotid artery course represents a direct risk factor for lesions of the petrous, lacerum and cavernous segments of the carotid artery. Early diagnosis of post-traumatic vascular injury may lead to prognosis improvement because of effectiveness of heparin anticoagulant therapy. Then vascular screening is recommendable in cases with complex fractures of the skull base and particularly fracturing along the course of the carotid artery. Magnetic resonance angiography may be considered the first line diagnostic tools for vascular screening. Angiography may be reserved for patients with a proven lesion or rapid neurological deterioration taking into account the possibility of interventional treatment.

An unusual stress fracture: Bilateral posterior longitudinal stress fracture of tibia.

PubMed

Malkoc, Melih; Korkmaz, Ozgur; Ormeci, Tugrul; Oltulu, Ismail; Isyar, Mehmet; Mahirogulları, Mahir

2014-01-01

Stress fractures (SF) occur when healthy bone is subjected to cyclic loading, which the normal carrying range capacity is exceeded. Usually, stress fractures occur at the metatarsal bones, calcaneus, proximal or distal tibia and tends to be unilateral. This article presents a 58-year-old male patient with bilateral posterior longitudinal tibial stress fractures. A 58 years old male suffering for persistent left calf pain and decreased walking distance for last one month and after imaging studies posterior longitudinal tibial stress fracture was detected on his left tibia. After six months the patient was admitted to our clinic with the same type of complaints in his right leg. All imaging modalities and blood counts were performed and as a result longitudinal posterior tibial stress fractures were detected on his right tibia. Treatment of tibial stress fracture includes rest and modified activity, followed by a graded return to activity commensurate with bony healing. We have applied the same treatment protocol and our results were acceptable but our follow up time short for this reason our study is restricted for separate stress fractures of the posterior tibia. Although the main localization of tibial stress fractures were unilateral, anterior and transverse pattern, rarely, like in our case, the unusual bilateral posterior localization and longitudinal pattern can be seen. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Use of advanced borehole geophysical techniques to delineate fractured-rock ground-water flow and fractures along water-tunnel facilities in northern Queens County, New York

USGS Publications Warehouse

Stumm, Frederick; Chu, Anthony; Lange, Andrew D.; Paillet, Frederick L.; Williams, John H.; Lane, John W.

2001-01-01

Advanced borehole geophysical methods were used to assess the geohydrology of crystalline bedrock along the course of a new water tunnel for New York City. The logging methods include natural gamma, spontaneous potential, single-point resistance, mechanical and acoustic caliper, focused electromagnetic induction, electromagnetic resistivity, magnetic susceptibility, borehole-fluid temperature and conductance, differential temperature, heat-pulse flowmeter, acoustic televiewer, borehole deviation, optical televiewer, and borehole radar. Integrated interpretation of the geophysical logs from an 825-foot borehole (1) provided information on the extent, orientation, and structure (foliation and fractures) within the entire borehole, including intensely fractured intervals from which core recovery may be poor; (2) delineated transmissive fracture zones intersected by the borehole and provided estimates of their transmissivity and hydraulic head; and (3) enabled mapping of the location and orientation of structures at distances as much as 100 ft from the borehole.Analyses of the borehole-wall image and the geophysical logs from the borehole on Crescent Street, in northern Queens County, are presented here to illustrate the application of the methods. The borehole penetrates gneiss and other crystalline bedrock that has predominantly southeastward dipping foliation and nearly horizontal and southeastward-dipping fractures. The heat-pulse flowmeter logs obtained under pumping and nonpumping conditions, together with the other geophysical logs, indicate five transmissive fracture zones. More than 90 percent of the open-hole transmissivity is associated with a fracture zone 272 feet BLS (below land surface). A transmissive zone at 787 feet BLS that consists of nearly parallel fractures lies within the projected tunnel path; here the hydraulic head is 12 to 15 feet lower than that of transmissive zones above the 315-foot depth. The 60-megahertz directional borehole radar logs indicate the location and orientation of two closely spaced radar reflectors that would intersect the projection of the borehole below its drilled depth.Subsequent excavation of the tunnel past the borehole allowed comparison of the log analysis with conditions observed in the tunnel. The tunnel was found to intersect gneiss with southeastward dipping foliation; many nearly horizontal fractures; and a southeastward dipping fracture zone whose location, character, and orientation was consistent with that of the mapped radar reflectors. The fracture zone produced inflow to the tunnel at a rate of 50 to 100 gallons per minute. All conditions indicated by the logging methods were consistent with those observed within the tunnel.

Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data

NASA Astrophysics Data System (ADS)

Thiele, Samuel T.; Grose, Lachlan; Samsu, Anindita; Micklethwaite, Steven; Vollgger, Stefan A.; Cruden, Alexander R.

2017-12-01

The advent of large digital datasets from unmanned aerial vehicle (UAV) and satellite platforms now challenges our ability to extract information across multiple scales in a timely manner, often meaning that the full value of the data is not realised. Here we adapt a least-cost-path solver and specially tailored cost functions to rapidly interpolate structural features between manually defined control points in point cloud and raster datasets. We implement the method in the geographic information system QGIS and the point cloud and mesh processing software CloudCompare. Using these implementations, the method can be applied to a variety of three-dimensional (3-D) and two-dimensional (2-D) datasets, including high-resolution aerial imagery, digital outcrop models, digital elevation models (DEMs) and geophysical grids. We demonstrate the algorithm with four diverse applications in which we extract (1) joint and contact patterns in high-resolution orthophotographs, (2) fracture patterns in a dense 3-D point cloud, (3) earthquake surface ruptures of the Greendale Fault associated with the Mw7.1 Darfield earthquake (New Zealand) from high-resolution light detection and ranging (lidar) data, and (4) oceanic fracture zones from bathymetric data of the North Atlantic. The approach improves the consistency of the interpretation process while retaining expert guidance and achieves significant improvements (35-65 %) in digitisation time compared to traditional methods. Furthermore, it opens up new possibilities for data synthesis and can quantify the agreement between datasets and an interpretation.

FracPaQ: a MATLAB™ Toolbox for the Quantification of Fracture Patterns

NASA Astrophysics Data System (ADS)

Healy, D.; Rizzo, R. E.; Cornwell, D. G.; Timms, N.; Farrell, N. J.; Watkins, H.; Gomez-Rivas, E.; Smith, M.

2016-12-01

The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, shapes and spatial distributions often exhibit some kind of order. In detail, there may be relationships among the different fracture attributes e.g. small fractures dominated by one orientation, larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture patterns and fracture attributes. This presentation describes an open source toolbox to quantify fracture patterns, including distributions in fracture attributes and their spatial variation. Software has been developed to quantify fracture patterns from 2-D digital images, such as thin section micrographs, geological maps, outcrop or aerial photographs or satellite images. The toolbox comprises a suite of MATLAB™ scripts based on published quantitative methods for the analysis of fracture attributes: orientations, lengths, intensity, density and connectivity. An estimate of permeability in 2-D is made using a parallel plate model. The software provides an objective and consistent methodology for quantifying fracture patterns and their variations in 2-D across a wide range of length scales. Our current focus for the application of the software is on quantifying the fracture patterns in and around fault zones. There is a large body of published work on the quantification of relatively simple joint patterns, but fault zones present a bigger, and arguably more important, challenge. The method presented is inherently scale independent, and a key task will be to analyse and integrate quantitative fracture pattern data from micro- to macro-scales. Planned future releases will incorporate multi-scale analyses based on a wavelet method to look for scale transitions, and combining fracture traces from multiple 2-D images to derive the statistically equivalent 3-D fracture pattern.

Detection of occult, undisplaced hip fractures with a dual-energy CT algorithm targeted to detection of bone marrow edema.

PubMed

Reddy, T; McLaughlin, P D; Mallinson, P I; Reagan, A C; Munk, P L; Nicolaou, S; Ouellette, H A

2015-02-01

The purpose of this study is to describe our initial clinical experience with dual-energy computed tomography (DECT) virtual non-calcium (VNC) images for the detection of bone marrow (BM) edema in patients with suspected hip fracture following trauma. Twenty-five patients presented to the emergency department at a level 1 trauma center between January 1, 2011 and January 1, 2013 with clinical suspicion of hip fracture and normal radiographs were included. All CT scans were performed on a dual-source, dual-energy CT system. VNC images were generated using prototype software and were compared to regular bone reconstructions by two musculoskeletal radiologists in consensus. Radiological and/or clinical diagnosis of fracture at 30-day follow-up was used as the reference standard. Twenty-one patients were found to have DECT-VNC signs of bone marrow edema. Eighteen of these 21 patients were true positive and three were false positive. A concordant fracture was clearly seen on bone reconstruction images in 15 of the 18 true positive cases. In three cases, DECT-VNC was positive for bone marrow edema where bone reconstruction CT images were negative. Four patients demonstrated no DECT-VNC signs of bone marrow edema: two cases were true negative, two cases were false negative. When compared with the gold standard of hip fracture determined at retrospective follow-up, the sensitivity of DECT-VNC images of the hip was 90 %, specificity was 40 %, positive predictive value was 86 %, and negative predictive value was 50 %. Our initial experience would suggest that DECT-VNC is highly sensitive but poorly specific in the diagnosis of hip fractures in patients with normal radiographs. The value of DECT-VNC primarily lies in its ability to help detect fractures which may be subtle or undetectable on bone reconstruction CT images.

Self-Sensing Composites: In-Situ Detection of Fibre Fracture

PubMed Central

Malik, Shoaib A.; Wang, Liwei; Curtis, Paul T.; Fernando, Gerard F.

2016-01-01

The primary load-bearing component in a composite material is the reinforcing fibres. This paper reports on a technique to study the fracture of individual reinforcing fibres or filaments in real-time. Custom-made small-diameter optical fibres with a diameter of 12 (±2) micrometres were used to detect the fracture of individual filaments during tensile loading of unreinforced bundles and composites. The unimpregnated bundles were end-tabbed and tensile tested to failure. A simple technique based on resin-infusion was developed to manufacture composites with a negligible void content. In both cases, optical fibre connectors were attached to the ends of the small-diameter optical fibre bundles to enable light to be coupled into the bundle via one end whilst the opposite end was photographed using a high-speed camera. The feasibility of detecting the fracture of each of the filaments in the bundle and composite was demonstrated. The in-situ damage detection technique was also applied to E-glass bundles and composites; this will be reported in a subsequent publication. PMID:27136555

High prevalence of radiological vertebral fractures in HIV-infected males.

PubMed

Torti, Carlo; Mazziotti, Gherardo; Soldini, Pier Antonio; Focà, Emanuele; Maroldi, Roberto; Gotti, Daria; Carosi, Giampiero; Giustina, Andrea

2012-06-01

Age-related co-morbidities including osteoporosis are relevant in patients responding to combination antiretroviral therapy (cART). Vertebral fractures are common osteoporotic fractures and their diagnosis is useful for managing at-risk individuals. However, there are few data from HIV-infected patients. Therefore, the aim of this study was to determine the prevalence of and factors associated with vertebral fractures in a population of HIV-infected males. A cross-sectional study of 160 HIV-infected patients with available chest X-rays was conducted from 1998 to 2010. One hundred and sixty-three males with comparable age and with no history of HIV infection were recruited as controls. Semi-quantitative evaluation of vertebral heights in lateral chest X-rays and quantitative morphometry assessment of centrally digitized images using dedicated morphometry software were utilized to detect prevalent vertebral fractures. The result showed that the vertebral fractures were detected in 43/160 (26.9%) HIV-infected patients and in 21/163 (12.9%) controls (P = 0.002). In HIV-infected patients with fractures, 27 had two or more fractures and ten patients had severe fractures. The prevalence of any fractures and multiple fractures in HIV-infected patients receiving cART (29.6 and 20.0%) was slightly higher than in HIV-infected patients not exposed to cART (17.1 and 5.7%), but significantly higher than control subjects (12.9 and 3.7%). At multivariable analyses, body mass index and diabetes mellitus were independently correlated with vertebral fractures in HIV-infected patients. We concluded that a significant proportion of HIV-infected males receiving cART showed vertebral fractures. Furthermore, proactive diagnosis of vertebral fragility fractures is particularly relevant in patients who are overweight or suffer from diabetes.

Stress field modelling from digital geological map data

NASA Astrophysics Data System (ADS)

Albert, Gáspár; Barancsuk, Ádám; Szentpéteri, Krisztián

2016-04-01

To create a model for the lithospheric stress a functional geodatabase is required which contains spatial and geodynamic parameters. A digital structural-geological map is a geodatabase, which usually contains enough attributes to create a stress field model. Such a model is not accurate enough for engineering-geological purposes because simplifications are always present in a map, but in many cases maps are the only sources for a tectonic analysis. The here presented method is designed for field geologist, who are interested to see the possible realization of the stress field over the area, on which they are working. This study presents an application which can produce a map of 3D stress vectors from a kml-file. The core application logic is implemented on top of a spatially aware relational database management system. This allows rapid and geographically accurate analysis of the imported geological features, taking advantage of standardized spatial algorithms and indexing. After pre-processing the map features in a GIS, according to the Type-Property-Orientation naming system, which was described in a previous study (Albert et al. 2014), the first stage of the algorithm generates an irregularly spaced point cloud by emitting a pattern of points within a user-defined buffer zone around each feature. For each point generated, a component-wise approximation of the tensor field at the point's position is computed, derived from the original feature's geodynamic properties. In a second stage a weighted moving average method calculates the stress vectors in a regular grid. Results can be exported as geospatial data for further analysis or cartographic visualization. Computation of the tensor field's components is based on the implementation of the Mohr diagram of a compressional model, which uses a Coulomb fracture criterion. Using a general assumption that the main principal stress must be greater than the stress from the overburden, the differential stress is calculated from the fracture criterion. The calculation includes the gravitational acceleration, the average density of rocks and the experimental 60 degree of the fracture angle from the normal of the fault plane. This way, the stress tensors are calculated as absolute pressure values per square meters on both sides of the faults. If the stress from the overburden is greater than 1 bar (i.e. the faults are buried), a confined compression would be present. Modelling this state of stress may result a confusing pattern of vectors, because in a confined position the horizontal stress vectors may point towards structures primarily associated with extension. To step over this, and to highlight the variability in the stress-field, the model calculates the vectors directly from the differential stress (practically subtracting the minimum principal stress from the critical stress). The result of the modelling is a vector map, which theoretically represents the minimum tectonic pressure in the moment, when the rock body breaks from an initial state. This map - together with the original fault-map - is suitable for determining those areas where unrevealed tectonic, sedimentary and lithological structures are possibly present (e.g. faults, sub-basins and intrusions). With modelling different deformational phases on the same area, change of the stress vectors can be detected which reveals not only the varying directions of the principal stresses, but the tectonic-driven sedimentation patterns too. The decrease of necessary critical stress in the case of a possible reactivation of a fault in subsequent deformation phase can be managed with the down-ranking of the concerning structural elements. Reference: Albert G., Ungvári ZS., Szentpéteri K. 2014: Modeling the present day stress field of the Pannonian Basin from neotectonic maps - In: Beqiraj A, Ionescu C, Christofides G, Uta A, Beqiraj Goga E, Marku S (eds.) Proceedings XX Congress of the Carpathian-Balkan Geological Association. Tirana: p. 2.

Tidal reorientation and the fracturing of Jupiter's moon Europa

NASA Technical Reports Server (NTRS)

Mcewen, A. S.

1986-01-01

The lineaments on Europa are discussed in terms of the orientation of the lineaments relative to the tensile stress trajectories due to tidal distortions and to nonsynchronous rotation. The cracks are noticeable by their darker albedo compared to the presumed water ice surrounding them. The stress trajectories for tidal distortion of a thin elastic shell are superimposed on Mercator projection maps of the lineaments. It is shown that the lineaments are mainly oriented at high angles to the tensile stress trajectories that would be expected for regularly occurring nonsynchronous rotation, i.e., extensional fractures would appear. The reorientation motions which would cause the fractures are estimated. It is suggested that the fractures occur episodically to release stresses built up on the tensile surface of the crust during the continuous nonsynchronous rotation of Europa.

Geologic Mapping and Paired Geochemical-Paleomagnetic Sampling of Reference Sections in the Grande Ronde Basalt: An Example from the Bingen Section, Columbia River Gorge, Washington

NASA Astrophysics Data System (ADS)

Sawlan, M.; Hagstrum, J. T.; Wells, R. E.

2011-12-01

We have completed comprehensive geochemical (GC) and paleomagnetic (PM) sampling of individual lava flows from eight reference stratigraphic sections in the Grande Ronde Basalt (GRB), Columbia River Basalt Group [Hagstrum et al., 2009, GSA Ann. Mtg, Portland (abst); Hagstrum et al., 2010, AGU Fall Mtg, San Francisco (abst)]. These sections, distributed across the Columbia Plateau and eastern Columbia River Gorge, contain as many as 30 flows, are up to 670 m thick, span upper magneto-stratigraphic zones R2 and N2, and, in some locations, also contain one or more N1 flows. In concert with GC and PM sampling, we have carried out detailed geologic mapping of these sections, typically at a scale of 1:3,000 to 1:5,000, using GPS, digital imagery from the National Aerial Imagery Program (NAIP), and compilation in GIS. GRB member and informal unit names of Reidel et al. [1989, GSA Sp. Paper 239] generally have been adopted, although two new units are identified and named within the N2 zone. Notably, a distinctive PM direction for intercalated lavas of several lower N2 units indicates coeval eruption of compositionally distinct units; this result contrasts with the scenario of serial stratigraphic succession of GRB units proposed by Reidel et al. [1989]. Our objectives in the mapping include: Confirming the integrity of the stratigraphic sequences by documenting flow contacts and intraflow horizons (changes in joint patterns or vesicularity); assessing fault displacements; and, establishing precisely located samples in geologic context such that selected sites can be unambiguously reoccupied. A geologic map and GC-PM data for the Bingen section, along the north side of the Columbia River, are presented as an example of our GRB reference section mapping and sampling. One of our thicker sections (670 m) along which 30 flows are mapped, the Bingen section spans 7 km along WA State Hwy 14, from near the Hood River Bridge ESE to Locke Lake. This section cuts obliquely through a broad, NE-trending anticline of the Yakima Fold Belt, with the section base (N1) beneath the fold crest and R2 and N2 flows exposed in the fold's SE limb. In addition to addressing our main mapping objectives, observations made in the course of mapping at Bingen and other sections have led to insights into the cooling, fracturing and emplacement of GRB lavas. A distinctive set of fractures, termed quench fractures, comprise subvertical, curviplanar fractures and flanking mini-columnar joints, and are attributed to ascent of steam, generated by conduction heating of groundwater, through recently emplaced flows [Sawlan and Moore, 2011, GSA Rocky Mtn-Cord. Sec. Mtg, Logan (abst)]. Quench fractures are widespread across the GRB extent and occur in flows at Bingen. We have identified small lava tubes (<2 m wide) in several sections, in both high-Mg and low-Mg flows. In relation to the large volumes of GRB flows, the lava tubes are notably diminutive. At Bingen and in the Buttermilk Canyon section (near Lone Rock, OR), pahoehoe toes are recognized in flows also containing lava tubes. While observations of lava tubes and pahoehoe toes are few to date, ropy pahoehoe and layered upper flow crusts are common in high-Mg flows. These characteristics - tubes, toes, ropes and crusts - indicate emplacement as pahoehoe flows.

Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures.

PubMed

Nachtrab, O; Cassar-Pullicino, V N; Lalam, R; Tins, B; Tyrrell, P N M; Singh, J

2012-12-01

MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Simulations of mechanical failure in ice: Implications of terrestrial fracture models as applied to they icy satellites of the outer solar system

NASA Astrophysics Data System (ADS)

Walker, C. C.; Bassis, J. N.

2011-12-01

At the South Pole of Enceladus, a small icy moon orbiting Saturn, is a heavily fractured ice plain surrounded by a nearly-circular mountain range. Remarkably, the Cassini orbiter detected jets of water emanating from the icy shell and into space, originating from 4 parallel "tiger stripe" rifts within the center of the ice plain. The tiger stripes imaged on Enceladus are morphologically similar to rifts observed to form under extensional stress regimes in terrestrial ice shelves; the putative subsurface ocean hypothesized beneath the icy shell strengthens the analogy that their formation may have similar mechanical origins. Past studies have also suggested that the tiger stripes are the result of a process similar to that of mid-ocean ridge spreading on the Earth, but it remains to be seen whether or not such motion is consistent with the mountainous features seen at the circular cliff-like boundary of the region. In an attempt to understand the formation of these tiger stripes and their relationship to the observed mountain chains, we apply a conceptual model in which the ice is considered to be less like a continuous fluid body and, instead, behaves like a granular material made up of discrete blocks of ice. The tidal forces on the small moon tug on the shell enough that it has been cracked many times over, motivating the assumption that the ice exists in a continuum between wholly intact ice and highly pre-fractured ice. We employ several experimental setups with the intention of mapping the deformation of the south polar segment of the shell, to determine the processes that may contribute to its observed morphological state. These setups range from large scale topographical models, e.g., simulating the build up of mountains and processes that lead to overall elevation differences in the region, to small-scale, and focus on the more detailed level of fracturing. We explore our ice-shelf rifting analogy by modeling both icy moon fracturing and ice shelf rifting to compare and contrast the failure modes that we observe, results that bolster both our comparative platform and, importantly, our understanding of fracture in ice shelves on the Earth as well. A similar approach could be applied to the chaos regions of Europa, where fractures are prevalent and whose underlying causes are not well understood.

On gravity from SST, geoid from SEASAT, and plate age and fracture zones in the Pacific

NASA Technical Reports Server (NTRS)

Marsh, B. D.; Marsh, J. G.; Williamson, R. G.

1983-01-01

Data from an additional 50 satellite-to-satellite tracking (SST) passes were combined with earlier measurements of the high degree and order (n, m, 12) gravity in the central Pacific. A composite map was produced which shows good agreement with conventional GEM models. Data from the SEASAT altimeter was reduced and found to agree well with both the SST and the GEM fields. The maps are dominated especially in the east, by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Further comparison with regional bathymetric data shows a remarkably close correlation with plate age. Each anomaly band is framed by those major fracture zones having large offsets. The regular spacing of these fractures seems to account for the fabric in the gravity fields. Other anomalies are accounted for by hot spots. The source of part of these anomalies is in the lithosphere itself. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantel without complete thermal equilibration is considered.

Pediatric craniofacial fractures due to violence: comparing violent and nonviolent mechanisms of injury.

PubMed

Mericli, Alexander F; DeCesare, Gary E; Zuckerbraun, Noel S; Kurland, Kristen S; Grunwaldt, Lorelei; Vecchione, Lisa; Losee, Joseph E

2011-07-01

This study examines the epidemiologic data of pediatric craniofacial fractures secondary to violence, comparing these data to craniofacial fractures sustained from all other causes. A retrospective review was completed on all patients who presented to the emergency department of a major urban children's hospital from 2000 to 2005 with a craniofacial fracture. Data were compared between patients with fractures due to violent and nonviolent mechanisms. Socioeconomic analysis was performed using Geographic Information System mapping and 2000 US Census data by postal code. One thousand five hundred twenty-eight patients were diagnosed with skull and/or facial fractures. Isolated skull fractures were excluded, leaving 793 patients in the study. Ninety-eight children were injured due to violence, and 695 were injured from a nonviolent cause. Patients with violence-related fractures were more likely to be older, male, and nonwhite and live in a socioeconomically depressed area. A greater number of patients with violence-related injuries sustained nasal and mandible angle fractures, whereas more patients with non-violence-related injuries sustained skull and orbital fractures. Those with violence-related craniofacial fractures had a lower percentage of associated multiorgan system injuries and a lower rate of hospital admissions and intensive care unit admissions. The rate of open reduction and internal fixation for craniofacial fractures was similar in both groups. Patients with violence-related fractures had fewer associated serious injuries and lower morbidity and lived in a more socioeconomically depressed area. The information gained from this descriptive study improves our ability to characterize this population of pediatric patients and to identify the associated constellation of injuries in such fractures.

The acousto-ultrasonic approach

NASA Technical Reports Server (NTRS)

Vary, Alex

1987-01-01

The nature and underlying rationale of the acousto-ultrasonic approach is reviewed, needed advanced signal analysis and evaluation methods suggested, and application potentials discussed. Acousto-ultrasonics is an NDE technique combining aspects of acoustic emission methodology with ultrasonic simulation of stress waves. This approach uses analysis of simulated stress waves for detecting and mapping variations of mechanical properties. Unlike most NDE, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of various flaws and material anomalies. Acousto-ultrasonics has been applied chiefly to laminated and filament-wound fiber reinforced composites. It has been used to assess the significant strength and toughness reducing effects that can be wrought by combinations of essentially minor flaws and diffuse flaw populations. Acousto-ultrasonics assesses integrated defect states and the resultant variations in properties such as tensile, shear, and flexural strengths and fracture resistance. Matrix cure state, porosity, fiber orientation, fiber volume fraction, fiber-matrix bonding, and interlaminar bond quality are underlying factors.

Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks

NASA Astrophysics Data System (ADS)

Chen, Mingjie; Sun, Yunwei; Fu, Pengcheng; Carrigan, Charles R.; Lu, Zhiming; Tong, Charles H.; Buscheck, Thomas A.

2013-08-01

Hydraulic fracturing has been used widely to stimulate production of oil, natural gas, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation often requires a large number of evaluations of objective functions and constraints from forward hydraulic fracturing models, which are computationally expensive and even prohibitive in some situations. Moreover, there are a variety of uncertainties associated with the pre-existing fracture distributions and rock mechanical properties, which affect the optimized decisions for hydraulic fracturing. In this study, a surrogate-based approach is developed for efficient optimization of hydraulic fracturing well design in the presence of natural-system uncertainties. The fractal dimension is derived from the simulated fracturing network as the objective for maximizing energy recovery sweep efficiency. The surrogate model, which is constructed using training data from high-fidelity fracturing models for mapping the relationship between uncertain input parameters and the fractal dimension, provides fast approximation of the objective functions and constraints. A suite of surrogate models constructed using different fitting methods is evaluated and validated for fast predictions. Global sensitivity analysis is conducted to gain insights into the impact of the input variables on the output of interest, and further used for parameter screening. The high efficiency of the surrogate-based approach is demonstrated for three optimization scenarios with different and uncertain ambient conditions. Our results suggest the critical importance of considering uncertain pre-existing fracture networks in optimization studies of hydraulic fracturing.

Identifying osteoporotic vertebral endplate and cortex fractures

PubMed Central

Santiago, Fernando Ruiz; Deng, Min; Nogueira-Barbosa, Marcello H.

2017-01-01

Osteoporosis is the most common metabolic bone disease, and vertebral fractures (VFs) are the most common osteoporotic fracture. A single atraumatic VF may lead to the diagnosis of osteoporosis. Prevalent VFs increase the risk of future vertebral and non-vertebral osteoporotic fracture independent of bone mineral density (BMD). The accurate and clear reporting of VF is essential to ensure patients with osteoporosis receive appropriate treatment. Radiologist has a vital role in the diagnosis of this disease. Several morphometrical and radiological methods for detecting osteoporotic VF have been proposed, but there is no consensus regarding the definition of osteoporotic VF. A vertebra may fracture yet not ever result in measurable changes in radiographic height or area. To overcome these difficulties, algorithm-based qualitative approach (ABQ) was developed with a focus on the identification of change in the vertebral endplate. Evidence of endplate fracture (rather than variation in vertebral shape) is the primary indicator of osteoporotic fracture according to ABQ criteria. Other changes that may mimic osteoporotic fractures should be systemically excluded. It is also possible that vertebral cortex fracture may not initially occur in endplate. Particularly, vertebral cortex fracture can occur in anterior vertebral cortex without gross vertebral deformity (VD), or fractures deform the anterior vertebral cortex without endplate disruption. This article aims to serve as a teaching material for physicians or researchers to identify vertebral endplate/cortex fracture (ECF). Emphasis is particularly dedicated to identifying ECF which may not be associated apparent vertebral body collapse. We believe a combined approach based on standardized radiologic evaluation by experts and morphometry measurement is the most appropriate approach to detect and classify VFs. PMID:29184768

Fracture detection logging tool

DOEpatents

Benzing, William M.

1992-06-09

A method and apparatus by which fractured rock formations are identified and their orientation may be determined includes two orthogonal motion sensors which are used in conjunction with a downhole orbital vibrator. The downhole vibrator includes a device for orienting the sensors. The output of the sensors is displayed as a lissajou figure. The shape of the figure changes when a subsurface fracture is encountered in the borehole. The apparatus and method identifies fractures rock formations and enables the azimuthal orientation of the fractures to be determined.

Hydro-fracture in the laboratory: matching diagnostic seismic signals to fracture networks

NASA Astrophysics Data System (ADS)

Gehne, S.; Benson, P. M.; Koor, N.; Dobson, K. J.; Enfield, M.; Barber, A.

2017-12-01

Hydraulic fracturing is a key process in both natural (e.g. dyke intrusion) and engineered environments (e.g. shale gas). To better understand this process, we present new data from simulated hydraulic fracturing in a controlled laboratory environment in order to track fracture nucleation (location) and propagation (velocity) in space and time to assess the fracture mechanics and developing fracture network. Fluid overpressure is used to generate a permeable network of micro tensile fractures in an anisotropic sandstone and a highly anisotropic shale. A newly developed technique, using a steel guide arrangement to direct pressurised fluid into a sealed section of an axially drilled conduit, allows the pore fluid to contact the rock directly and to initiate tensile fractures from a pre-defined zone inside the sample. Acoustic emission location is used to record and map the nucleation and development of the micro-fracture network. For both rock types, fractures progresses parallel to the bedding plane (short-transverse) if the bedding plane is aligned with the direction of σ1 requiring breakdown pressures of approximately 7 and 13MPa respectively at a confining pressure of 8MPa. The data also indicates a more ductile behaviour of the shale than expected. We use X-Ray Computed Tomography (CT) to evaluate the evolved fracture network in terms of fracture pattern and aperture. Hydraulic fracturing produces very planar fractures in the shale, with axial fractures over the entire length of the sample broadly following the bedding. In contrast, fractures in the sandstone are more diffuse, linking pore spaces as they propagate. However, secondary micro cracking, branching of the main fracture, are also observed. These new experiments suggest that fracture pattern, fracture propagation trajectories, and fracturing fluid pressures are predominantly controlled by the interaction between the anisotropic mechanical properties of the rock and the anisotropic stress environment.

A Modified Direct-Reading Azimuth Protractor

ERIC Educational Resources Information Center

Larson, William C.; Pugliese, Joseph M.

1977-01-01

Describes the construction of a direct-reading azimuth protractor (DRAP) used for mapping fracture and joint-surface orientations in underground mines where magnetic disturbances affect typical geologic pocket transit. (SL)

Structural lineaments of Gaspe from ERTS imagery

NASA Technical Reports Server (NTRS)

Steffensen, R.

1973-01-01

A test study was conducted to assess the value of ERTS images for mapping geologic features of the Gaspe Peninsula, Quebec. The specific objectives of the study were: 1) to ascertain the best procedure to follow in order to obtain valuable geologic data as a result of interpretation; and 2) to indicate in which way these data could relate to mineral exploration. Of the four spectral bands of the Multispectral scanner, the band from 700 to 800 nanometers, which seems to possess the best informational content for geologic study, was selected for analysis. The original ERTS image at a scale of 1:3,700,000 was enlarged about 15 times and reproduced on film. Geologically meaningful lines, called structural lineaments, were outlined and classified according to five categories: morpho-lithologic boundaries, morpho-lithologic lineaments, fault traces, fracture zones and undefined lineaments. Comparison with the geologic map of Gaspe shows that morpho-lithologic boundaries correspond to contacts between regional stratigraphic units. Morpholithologic lineaments follow bedding trends, whereas fracture traces appear as sets of parallel lineaments, intersecting at high angles the previous category of lineaments. Fault traces mark more precisely the location of faults already mapped and spot the presence of presumable faults, not indicated on the geologic map.

Topographic and Air-Photo Lineaments in Various Locations Related to Geothermal Exploration in Colorado

DOE Data Explorer

Richard Zehner

2012-02-01

These line shapefiles trace apparent topographic and air-photo lineaments in various counties in Colorado. It was made in order to identify possible fault and fracture systems that might be conduits for geothermal fluids, as part of a DOE reconnaissance geothermal exploration program. Geothermal fluids commonly utilize fault and fractures in competent rocks as conduits for fluid flow. Geothermal exploration involves finding areas of high near-surface temperature gradients, along with a suitable "plumbing system" that can provide the necessary permeability. Geothermal power plants can sometimes be built where temperature and flow rates are high. This line shapefile is an attempt to use desktop GIS to delineate possible faults and fracture orientations and locations in highly prospective areas prior to an initial site visit. Geochemical sampling and geologic mapping could then be centered around these possible faults and fractures. To do this, georeferenced topographic maps and aerial photographs were utilized in an existing GIS, using ESRI ArcMap 10.0 software. The USA_Topo_Maps and World_Imagery map layers were chosen from the GIS Server at server.arcgisonline.com, using a UTM Zone 13 NAD27 projection. This line shapefile was then constructed over that which appeared to be through-going structural lineaments in both the aerial photographs and topographic layers, taking care to avoid manmade features such as roads, fence lines, and utility right-of-ways. Still, it is unknown what actual features these lineaments, if they exist, represent. Although the shapefiles are arranged by county, not all areas within any county have been examined for lineaments. Work was focused on either satellite thermal infrared anomalies, known hot springs or wells, or other evidence of geothermal systems. Finally, lineaments may be displaced somewhat from their actual location, due to such factors as shadow effects with low sun angles in the aerial photographs. Credits: These lineament shapefile was created by Geothermal Development Associates, as part of a geothermal geologic reconnaissance performed by Flint Geothermal, LLC, of Denver Colorado. Use Limitation: These shapefiles were constructed as an aid to geothermal exploration in preparation for a site visit for field checking. We make no claims as to the existence of the lineaments, their location, orientation, and/or nature.

77 FR 29212 - Airworthiness Directives; The Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-17

... Company Model 777 airplanes. This AD was prompted by reports of fractured and missing latch pin retention... inspections for fractured or missing latch pin retention bolts, replacement of existing titanium bolts with... AD to detect and correct fractured and missing latch pin retention bolts, which could result in...

77 FR 39153 - Airworthiness Directives; The Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-02

... correct corrosion of the carriage spindle, which could result in a fracture; fracture of both the inboard... Directorate, 1601 Lind Avenue SW., Renton, Washington. For information on the availability of this material at... load. Corrosion of the carriage spindle, if not detected and corrected, could result in fracture of the...

Influence of scale-dependent fracture intensity on block size distribution and rock slope failure mechanisms in a DFN framework

NASA Astrophysics Data System (ADS)

Agliardi, Federico; Galletti, Laura; Riva, Federico; Zanchi, Andrea; Crosta, Giovanni B.

2017-04-01

An accurate characterization of the geometry and intensity of discontinuities in a rock mass is key to assess block size distribution and degree of freedom. These are the main controls on the magnitude and mechanisms of rock slope instabilities (structurally-controlled, step-path or mass failures) and rock mass strength and deformability. Nevertheless, the use of over-simplified discontinuity characterization approaches, unable to capture the stochastic nature of discontinuity features, often hampers a correct identification of dominant rock mass behaviour. Discrete Fracture Network (DFN) modelling tools have provided new opportunities to overcome these caveats. Nevertheless, their ability to provide a representative picture of reality strongly depends on the quality and scale of field data collection. Here we used DFN modelling with FracmanTM to investigate the influence of fracture intensity, characterized on different scales and with different techniques, on the geometry and size distribution of generated blocks, in a rock slope stability perspective. We focused on a test site near Lecco (Southern Alps, Italy), where 600 m high cliffs in thickly-bedded limestones folded at the slope scale impend on the Lake Como. We characterized the 3D slope geometry by Structure-from-Motion photogrammetry (range: 150-1500m; point cloud density > 50 pts/m2). Since the nature and attributes of discontinuities are controlled by brittle failure processes associated to large-scale folding, we performed a field characterization of meso-structural features (faults and related kinematics, vein and joint associations) in different fold domains. We characterized the discontinuity populations identified by structural geology on different spatial scales ranging from outcrops (field surveys and photo-mapping) to large slope sectors (point cloud and photo-mapping). For each sampling domain, we characterized discontinuity orientation statistics and performed fracture mapping and circular window analyses in order to measure fracture intensity (P21) and persistence (trace length distributions). Then, we calibrated DFN models for different combinations of P21/P32 and trace length distributions, characteristic of data collected on different scale. Comparing fracture patterns and block size distributions obtained from different models, we outline the strong influence of field data quality and scale on the rock mass behaviours predicted by DFN. We show that accounting for small scale features (close but short fractures) results in smaller but more interconnected blocks, eventually characterized by low removability and partly supported by intact rock strength. On the other hand, DFN based on data surveyed on slope scale enhance the structural control of persistent fracture on the kinematic degree-of freedom of medium-sized blocks, with significant impacts on the selection and parametrization of rock slope stability modelling approaches.

Measuring the hydraulic fracture-induced deformation of reservoirs and adjacent rocks employing a deeply buried inclinometer array: GRI/DOE multi-site project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branagan, P.T.; Warpinski, N.R.; Engler, B.

A vertical inclinometer array consisting of six biaxial tiltmeters was cemented behind pipe at depths between 4,273 and 4,628 ft. This wide-aperture array provided real-time tilt profiles corresponding to a series of seven hydraulic fractures being conducted in a nearby offset well in a fluvial sandstone reservoir. Array profiles for three KCl water fracs indicated that height growth was confined to the gross thickness of the reservoir despite extensive fracture length extension. Long-term monitoring of the array suggests that a substantial residual frac: width remained long after fracture closure occurred. For two 400-bbl linear gel minifracs, some height growth wasmore » observed but it was not extensive. Tilt amplitudes related to expanded frac widths were found to increase as would be expected with these thicker frac fluids. When cross-linker and proppant were included in the last fracture, tilt-derived heights were seen to grow rapidly extending into the bounding layers as the more complex fluids entered the fracture system. This inclinometer array was one of several independent, yet complimentary, fracture diagnostics tools that included crosswell multilevel microseismic arrays, FRACPRO{reg_sign} and a remote fracture intersection well. Their purpose was to provide integrated field-scale data regarding hydraulic fracture dynamics and geometry that would be used to construct accurate fracture mapping and diagnostic techniques.« less

Fracture of a Brittle-Particle Ductile Matrix Composite with Applications to a Coating System

NASA Astrophysics Data System (ADS)

Bianculli, Steven J.

In material systems consisting of hard second phase particles in a ductile matrix, failure initiating from cracking of the second phase particles is an important failure mechanism. This dissertation applies the principles of fracture mechanics to consider this problem, first from the standpoint of fracture of the particles, and then the onset of crack propagation from fractured particles. This research was inspired by the observation of the failure mechanism of a commercial zinc-based anti-corrosion coating and the analysis was initially approached as coatings problem. As the work progressed it became evident that failure mechanism was relevant to a broad range of composite material systems and research approach was generalized to consider failure of a system consisting of ellipsoidal second phase particles in a ductile matrix. The starting point for the analysis is the classical Eshelby Problem, which considered stress transfer from the matrix to an ellipsoidal inclusion. The particle fracture problem is approached by considering cracks within particles and how they are affected by the particle/matrix interface, the difference in properties between the particle and matrix, and by particle shape. These effects are mapped out for a wide range of material combinations. The trends developed show that, although the particle fracture problem is very complex, the potential for fracture among a range of particle shapes can, for certain ranges in particle shape, be considered easily on the basis of the Eshelby Stress alone. Additionally, the evaluation of cracks near the curved particle/matrix interface adds to the existing body of work of cracks approaching bi-material interfaces in layered material systems. The onset of crack propagation from fractured particles is then considered as a function of particle shape and mismatch in material properties between the particle and matrix. This behavior is mapped out for a wide range of material combinations. The final section of this dissertation qualitatively considers an approach to determine critical particle sizes, below which crack propagation will not occur for a coating system that exhibited stable cracks in an interfacial layer between the coating and substrate.

The heterogeneous ice shell thickness of Enceladus

NASA Astrophysics Data System (ADS)

Lucchetti, Alice; Pozzobon, Riccardo; Mazzarini, Francesco; Cremonese, Gabriele; Massironi, Matteo

2016-10-01

Saturn's moon Enceladus is the smallest Solar System body that presents an intense geologic activity on its surface. Plumes erupting from Enceladus' South Polar terrain (SPT) provide direct evidence of a reservoir of liquid below the surface. Previous analysis of gravity data determined that the ice shell above the liquid ocean must be 30-40 km thick from the South Pole up to 50° S latitude (Iess et al., 2014), however, understand the global or regional nature of the ocean beneath the ice crust is still challenging. To infer the thickness of the outer ice shell and prove the global extent of the ocean, we used the self-similar clustering method (Bonnet et al., 2001; Bour et al., 2002) to analyze the widespread fractures of the Enceladus's surface. The spatial distribution of fractures has been analyzed in terms of their self-similar clustering and a two-point correlation method was used to measure the fractal dimension of the fractures population (Mazzarini, 2004, 2010). A self-similar clustering of fractures is characterized by a correlation coefficient with a size range defined by a lower and upper cut-off, that represent a mechanical discontinuity and the thickness of the fractured icy crust, thus connected to the liquid reservoir. Hence, this method allowed us to estimate the icy shell thickness values in different regions of Enceladus from SPT up to northern regions.We mapped fractures in ESRI ArcGis environment in different regions of the satellite improving the recently published geological map (Crow-Willard and Pappalardo, 2015). On these regions we have taken into account the fractures, such as wide troughs and narrow troughs, located in well-defined geological units. Firstly, we analyzed the distribution of South Polar Region fracture patterns finding an ice shell thickness of ~ 31 km, in agreement with gravity measurements (Iess et al., 2014). Then, we applied the same approach to other four regions of the satellite inferring an increasing of the ice shell thickness from 31 to 70 km from the South Pole to northern regions. By these findings, we prove the global extent of the ocean underneath the ice crust of the satellite.

Enhanced oil recovery utilizing high-angle wells in the Frontier Formation, Badger Basin Field, Park County, Wyoming. Final report for the period October 1992--October 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, J.P.; Fortmann, R.G.

1994-12-01

Badger Basin Field, discovered in 1931, produces at stripper rates from low-permeability fractured sandstones of the Upper Cretaceous Frontier Formation. Only 15% of the estimated 25 million barrels of oil originally in-place will be produced from the twenty-two attempted vertical completions. This project will increase recoverable reserves through a better understanding of the reservoir and factors which control production. Characterization of the reservoir has been accomplished through an integrated engineering, geological and geophysical approach. Production data, drilling and completion techniques, and relative location of wells on the anticline were reviewed and related to productivity. Literature was reviewed for interpretations onmore » preferred flow directions on anticlinal structures. A structure map of the producing Frontier reservoir was constructed. Porosity development and its relationship to fracture networks was examined petrographically. Fractures in core were described and oriented using paleomagnetic techniques. Azimuths of fractures in outcrop were compared to fracture azimuths measured in the core. A 17 square-mile 3D seismic survey was designed, acquired and processed. Interpretation is being performed on a Sun workstation using Landmark Graphics software. Time-structure and amplitude-distribution maps will be constructed on three Frontier horizons. A location for a high-angle well will be chosen. The slant/horizontal test will be drilled and completed to increase recovery of reserves. Transfer of successful technologies will be accomplished by technical publications and presentations, and access to project materials, data, and field facilities.« less

Failure analysis of explanted sternal wires.

PubMed

Shih, Chun-Ming; Su, Yea-Yang; Lin, Shing-Jong; Shih, Chun-Che

2005-05-01

To classify and understand the mechanisms of surface damages and fracture mechanisms of sternal wires, explanted stainless steel sternal wires were collected from patients with sternal dehiscence following open-heart surgery. Surface alterations and fractured ends of sternal wires were examined and analyzed. Eighty fractured wires extracted from 25 patients from January 1999 to December 2003, with mean implantation interval of 55+/-149 days (range 5-729 days) after cardiac surgery, were studied by various techniques. The extracted wires were cleaned and the fibrotic tissues were removed. Irregularities and fractured ends were assayed by a scanning electron microscopy. After stereomicroscopy and documentation, the explants were cleaned with 1% sodium hypochlorite to remove the blood and tissues and was followed by cleaned with deionized water and alcohol. The explants were examined by stereomicroscopy, and irregularities on surface and fracture surfaces of sternal wires were assayed by scanning electron microscopy, energy dispersive X-ray analysis (EDAX) and X-ray mapping. The explants with surrounding fibrotic tissue were stained and examined with stereomicroscopy and transmission electronic microscopy. Corrosion pits were found on the surface of explanted sternal wires. EDAX and X-ray mapping examinations revealed diminution of nickel concentration in the severely corroded pits on sternal wires. A feature of transgranular cracking was observed for stress corrosion cracking and striation character for typical corrosion fatigue was also identified. TEM examination of tissue showed the metallic particles in phagolysosomes of macrophages inside the surrounding sternal tissue. The synergic effect of hostile environment and the stress could be the precursors of failures for sternal wires.

Quantitative geometric description of fracture systems in an andesite lava flow using terrestrial laser scanner data

NASA Astrophysics Data System (ADS)

Massiot, Cécile; Nicol, Andrew; Townend, John; McNamara, David D.; Garcia-Sellés, David; Conway, Chris E.; Archibald, Garth

2017-07-01

Permeability hosted in andesitic lava flows is dominantly controlled by fracture systems, with geometries that are often poorly constrained. This paper explores the fracture system geometry of an andesitic lava flow formed during its emplacement and cooling over gentle paleo-topography, on the active Ruapehu volcano, New Zealand. The fracture system comprises column-forming and platy fractures within the blocky interior of the lava flow, bounded by autobreccias partially observed at the base and top of the outcrop. We use a terrestrial laser scanner (TLS) dataset to extract column-forming fractures directly from the point-cloud shape over an outcrop area of ∼3090 m2. Fracture processing is validated using manual scanlines and high-resolution panoramic photographs. Column-forming fractures are either steeply or gently dipping with no preferred strike orientation. Geometric analysis of fractures derived from the TLS, in combination with virtual scanlines and trace maps, reveals that: (1) steeply dipping column-forming fracture lengths follow a scale-dependent exponential or log-normal distribution rather than a scale-independent power-law; (2) fracture intensities (combining density and size) vary throughout the blocky zone but have similar mean values up and along the lava flow; and (3) the areal fracture intensity is higher in the autobreccia than in the blocky zone. The inter-connected fracture network has a connected porosity of ∼0.5 % that promote fluid flow vertically and laterally within the blocky zone, and is partially connected to the autobreccias. Autobreccias may act either as lateral permeability connections or barriers in reservoirs, depending on burial and alteration history. A discrete fracture network model generated from these geometrical parameters yields a highly connected fracture network, consistent with outcrop observations.

Whitby Mudstone, flow from matrix to fractures

NASA Astrophysics Data System (ADS)

Houben, Maartje; Hardebol, Nico; Barnhoorn, Auke; Boersma, Quinten; Peach, Colin; Bertotti, Giovanni; Drury, Martyn

2016-04-01

Fluid flow from matrix to well in shales would be faster if we account for the duality of the permeable medium considering a high permeable fracture network together with a tight matrix. To investigate how long and how far a gas molecule would have to travel through the matrix until it reaches an open connected fracture we investigated the permeability of the Whitby Mudstone (UK) matrix in combination with mapping the fracture network present in the current outcrops of the Whitby Mudstone at the Yorkshire coast. Matrix permeability was measured perpendicular to the bedding using a pressure step decay method on core samples and permeability values are in the microdarcy range. The natural fracture network present in the pavement shows a connected network with dominant NS and EW strikes, where the NS fractures are the main fracture set with an orthogonal fracture set EW. Fracture spacing relations in the pavements show that the average distance to the nearest fracture varies between 7 cm (EW) and 14 cm (NS), where 90% of the matrix is 30 cm away from the nearest fracture. By making some assumptions like; fracture network at depth is similar to what is exposed in the current pavements and open to flow, fracture network is at hydrostatic pressure at 3 km depth, overpressure between matrix and fractures is 10% and a matrix permeability perpendicular to the bedding of 0.1 microdarcy, we have calculated the time it takes for a gas molecule to travel to the nearest fracture. These input values give travel times up to 8 days for a distance of 14 cm. If the permeability is changed to 1 nanodarcy or 10 microdarcy travel times change to 2.2 years or 2 hours respectively.

Radionuclide gas transport through nuclear explosion-generated fracture networks

DOE PAGES

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; ...

2015-12-17

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gasmore » breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.« less

Continuous pulse oximeter monitoring for inapparent hypoxemia after long bone fractures.

PubMed

Wong, Margaret Wan Nar; Tsui, Hon For; Yung, Shu Heng; Chan, Kai Ming; Cheng, Jack Chun Yiu

2004-02-01

Continuous pulse oximeter monitoring (CPOM) and daily intermittent arterial blood gas (ABG) were used to define the incidence, pattern, and severity of inapparent hypoxemia after long bone fractures. Twenty long bone fracture patients and 19 normal control patients were studied. CPOM, daily ABG, hypoxic symptoms, and features of fat embolism syndrome were monitored for 72 hours after fractures and after surgical interventions. CPOM trend curves showed that all fracture patients except one had recurrent desaturations below 90% Sao2 of varying duration and depth. The lowest Sao2 was down to 60% and the longest episode lasted for 1.47 hours. ABG analysis could not show the recurrent phenomena and never detected the corresponding desaturation episodes. Long bone fracture patients had more desaturation episodes, longer total desaturation duration, and larger total area under desaturation curves in both the postfracture and postoperative periods (p < 0.05). The mean Sao2 was significantly lower in the postfracture period. Although most patients remained asymptomatic and recovered spontaneously, two required transient oxygen therapy and one progressed to fat embolism syndrome. Inapparent hypoxia with profound desaturation is common after long bone fractures. CPOM of all patients admitted with long bone fractures is recommended for early detection. In patients who develop inapparent hypoxia, additional pulmonary insult should be avoided or undertaken with care and well timed.

Radionuclide gas transport through nuclear explosion-generated fracture networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gasmore » breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.« less

Filaments in Carbonaceous Meteorites: Mineral Crystals, Modern Bio-Contaminants or Indigenous Microfossils of Trichomic Prokaryotes?

NASA Technical Reports Server (NTRS)

Hoover, Richard B.; Borisyak, A. A.

2011-01-01

Environmental (ESEM) and Field Emission Scanning Electron Microscopy (FESEM) investigations have resulted in the detection of a large number of complex filaments in a variety of carbonaceous meteorites. Many of the filaments were observed to be clearly embedded the rock matrix of freshly fractured interior surfaces of the meteorites. The high resolution images obtained combined with tilt and rotation of the stage provide 3-dimensional morphological and morphometric data for the filaments. Calibrated Energy Dispersive X-ray Spectroscopy (EDS) and 2-D elemental X-ray maps have provided information on the chemical compositions of the filaments and the minerals of the associated meteorite rock matrix. These observations are used to evaluate diverse hypotheses regarding the possible abiotic or biogenic nature of the filaments found embedded in these meteorites.

Detection of Fractured Endodontic Instruments in Root Canals: Comparison between Different Digital Radiography Systems and Cone-beam Computed Tomography.

PubMed

Ramos Brito, Ana Caroline; Verner, Francielle Silvestre; Junqueira, Rafael Binato; Yamasaki, Mayra Cristina; Queiroz, Polyane Mazucato; Freitas, Deborah Queiroz; Oliveira-Santos, Christiano

2017-04-01

This study compared the detection of fractured instruments in root canals with and without filling by periapical radiographs from 3 digital systems and cone-beam computed tomographic (CBCT) images with different resolutions. Thirty-one human molars (80 canals) were used. Root canals were divided into the following groups: the control group, without fillings; the fracture group, without fillings and with fractured files; the fill group, filled; and the fill/fracture group, filled and with fractured files. Digital radiographs in ortho-, mesio-, and distoradial directions were performed in 2 semidirect systems (VistaScan [Dürr Dental, Beitigheim-Bissinger, Germany] and Express [Instrumentarium Imaging, Tuusula, Finland]) and a direct system (SnapShot [Instrumentarium Imaging]). CBCT images were acquired with 0.085-mm and 0.2-mm voxel sizes. All images were assessed and reassessed by 4 observers for the presence or absence of fractured files on a 5-point scale. The sensitivity, specificity, and accuracy were calculated. In the absence of filling, accuracy values were high, and there were no statistical differences among the radiographic techniques, different digital systems, or the different CBCT voxels sizes. In the presence of filling, the accuracy of periapical radiographs was significantly higher than CBCT images. In general, SnapShot showed higher accuracy than VistaScan and Express. Periapical radiographs in 1 incidence were accurate for the detection of fractured endodontic instruments inside the root canal in the absence or presence of filling, suggesting that this technique should be the first choice as well as the direct digital radiographic system. In the presence of filling, the decision to perform a CBCT examination must take into consideration its low accuracy. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Assessment of fracture-induced anisotropy in the Austin Chalk Formation (Upper Cretaceous), central Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, D.A.

1990-05-01

This study relates geophysical and geological data to the detection of fractures and their influence on the movement of fluid in the Atco Member of the Austin Chalk in central Texas. In areas of production, the Austin Chalk has very low matrix permeabilities, with hydrocarbons confined to zones of near-vertical, stress-aligned fractures. Horizontal drilling has been estimated to increase per well reserves in the Austin Chalk from 75,000 bbl and 82 mmcf to 500,000 bbl and 500 mmcf. The objective of deviated wells in the Austin Chalk is to intersect at right angles as many of the hydrocarbon-prone fracture zonesmore » as possible. Therefore, the detection and description of these fracture zones prior to drilling is critical. Fractures have been proven to influence the velocities of shear waves. To assess shear wave velocities in different directions, several shear wave refraction and three-component vertical seismic profiles have been acquired. These data provided a measure of the fracture-induced shear wave anisotropy and an indication of the dominant fracture trend. Other data, including azimuthal resistivity surveys, cores, and aerial photographs, provided additional control for evaluating the fractures. The final phase of the study compares the geophysical and geological interpretations to the result of shallow groundwater pumping tests. The pumping tests have been conducted in vertical boreholes and were designed to evaluate the influence of the fracturing on fluid movement.« less

[Imaging of diabetic osteopathy].

PubMed

Patsch, J; Pietschmann, P; Schueller-Weidekamm, C

2015-04-01

Diabetic bone diseases are more than just osteoporosis in patients with diabetes mellitus (DM): a relatively high bone mineral density is paired with a paradoxically high risk of fragility fractures. Diabetics exhibit low bone turnover, osteocyte dysfunction, relative hypoparathyroidism and an accumulation of advanced glycation end products in the bone matrix. Besides typical insufficiency fractures, diabetics show a high risk for peripheral fractures of the lower extremities (e.g. metatarsal fractures). The correct interdisciplinary assessment of fracture risks in patients with DM is therefore a clinical challenge. There are two state of the art imaging methods for the quantification of fracture risks: dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). Radiography, multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are suitable for the detection of insufficiency fractures. Novel research imaging techniques, such as high-resolution peripheral quantitative computed tomography (HR-pQCT) provide non-invasive insights into bone microarchitecture of the peripheral skeleton. Using MR spectroscopy, bone marrow composition can be studied. Both methods have been shown to be capable of discriminating between type 2 diabetic patients with and without prevalent fragility fractures and thus bear the potential of improving the current standard of care. Currently both methods remain limited to clinical research applications. DXA and HR-pQCT are valid tools for the quantification of bone mineral density and assessment of fracture risk in patients with DM, especially if interpreted in the context of clinical risk factors. Radiography, CT and MRI are suitable for the detection of insufficiency fractures.

Magnetic resonance imaging in stress fractures and shin splints.

PubMed

Aoki, Yoshimitsu; Yasuda, Kazunori; Tohyama, Harukazu; Ito, Hirokazu; Minami, Akio

2004-04-01

The purpose of the current study was to determine whether stress fractures and shin splints could be discriminated with MRI in the early phase. Twenty-two athletes, who had pain in the middle or distal part of their leg during or after sports activity, were evaluated with radiographs and MRI scans. Stress fractures were diagnosed when consecutive radiographs showed local periosteal reaction or a fracture line, and shin splints were diagnosed in all the other cases. In all eight patients with stress fractures, an abnormally wide high signal in the localized bone marrow was the most detectable in the coronal fat-suppressed MRI scan. In 11 patients with shin splints, the coronal fat-suppressed MRI scans showed a linear abnormally high signal along the medial posterior surface of the tibia, and in seven patients with shin splints, the MRI scans showed a linear abnormally high signal along the medial bone marrow. No MRI scans of shin splints showed an abnormally wide high signal in the bone marrow as observed on MRI scans of stress fractures. This study showed that fat-suppressed MRI is useful for discrimination between stress fracture and shin splints before radiographs show a detectable periosteal reaction in the tibia.

Spatial Distribution and Characteristics of Graben on the Lunar Nearside

NASA Astrophysics Data System (ADS)

Nahm, Amanda

2016-04-01

Faults and fractures are visible records of the stresses operating on and in planetary bodies. On the Moon, tectonic structures are concentrated on the nearside and are spatially associated with the maria. Large-scale graben may be the oldest tectonic structures on the Moon, with current estimates suggesting cessation of normal faulting around 3.6 Ga [e.g., 1, 2]. However, recent work [3] has found that normal faulting at Rupes Recta is younger than 3.2 Ga, indicating that the timing of graben formation and extensional tectonics on the Moon may be less well constrained than previously thought. Mapping of graben on the lunar nearside (270° to 90° E, 70°N to 70°S) at a scale of 1:500,000 has been completed, a significant improvement over earlier maps produced using low resolution pre-Lunar Reconnaissance Orbiter (LRO) data at scales of 1:5 million and 1:1 million. Based on map view morphology, the mapped graben have been divided into 4 categories: arcuate graben, graben in floor fractured craters, lineaments, and linear graben. The general graben morphology is similar for 3 of the groups: steep walls, relatively flat floors, and resolvable (near constant) widths. However the map view morphology differs in detail; linear graben are roughly linear, while arcuate graben are highly curved along their length and often are concentric to basin margins. Floor fractured craters (FFC) are craters with floors cut by radial, concentric, and/or polygonal fractures and mapped graben that occur within these craters are classified here as graben in FFC. Lineaments are defined here as structures that may follow the trends of identified graben in the area, but are narrow, shallow, V-shaped depressions. These lineaments may not be graben, but are likely to have formed in a similar stress field. Generally, mapped graben are concentrated near the margins of the nearside maria as observed previously, but some structures have been mapped within the maria or in the highlands far from mare margins. In some places within and on the margins of the maria, graben are observed to cut 'highland islands,' that is, graben cut older highland terrain but not mare. This observation indicates that graben in these locations are younger than the highland material but older than the maria, providing a means with which to constrain the timing of faulting, critical for understanding the temporal distribution and evolution of stresses on the lunar nearside. In addition, these observations will help determine the source(s) of stress responsible for the formation of graben on the lunar nearside. References: [1] Lucchitta and Watkins (1978), Proc. Lunar Planet. Sci. Conf. 9, 3459-3472. [2] Watters and Johnson (2010), in Planetary Tectonics, pp. 121-182, Cambridge University Press. [3] Nahm and Schultz (2013), Geol. Soc. Sp. Pub. 401, 377-394.

Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR.

PubMed

Widmann, G; Dalla Torre, D; Hoermann, R; Schullian, P; Gassner, E M; Bale, R; Puelacher, W

2015-04-01

The influence of dose reductions on diagnostic quality using a series of high-resolution ultralow-dose computed tomography (CT) scans for computer-assisted planning and surgery including the most recent iterative reconstruction algorithms was evaluated and compared with the fracture detectability of a standard cranial emergency protocol. A human cadaver head including the mandible was artificially prepared with midfacial and orbital fractures and scanned using a 64-multislice CT scanner. The CT dose index volume (CTDIvol) and effective doses were calculated using application software. Noise was evaluated as the standard deviation in Hounsfield units within an identical region of interest in the posterior fossa. Diagnostic quality was assessed by consensus reading of a craniomaxillofacial surgeon and radiologist. Compared with the emergency protocol at CTDIvol 35.3 mGy and effective dose 3.6 mSv, low-dose protocols down to CTDIvol 1.0 mGy and 0.1 mSv (97% dose reduction) may be sufficient for the diagnosis of dislocated craniofacial fractures. Non-dislocated fractures may be detected at CTDIvol 2.6 mGy and 0.3 mSv (93% dose reduction). Adaptive statistical iterative reconstruction (ASIR) 50 and 100 reduced average noise by 30% and 56%, and model-based iterative reconstruction (MBIR) by 93%. However, the detection rate of fractures could not be improved due to smoothing effects. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

[Clinical pathway for hip fracture patients].

PubMed

Sáez López, Pilar; Sánchez Hernández, Natalia; Paniagua Tejo, Sonsoles; Valverde García, José Antonio; Montero Díaz, Margarita; Alonso García, Noelia; Freites Esteve, Alfonso

2015-01-01

Hip fracture in the elderly often occurs in patients with high co-morbidity. Effective management requires a comprehensive and multidisciplinary approach. To evaluate the effect of a quality improvement intervention in the detection and treatment of complications in elderly patients admitted for hip fracture. A comparative study was conducted between two groups of patients admitted for hip fracture prior to 2010, and after a quality improvement intervention in 2013. The intervention consisted of implementing improved multidisciplinary measures in accordance with recent scientific evidence. The degree of compliance of the implemented measures was quantified. Patients admitted due to hip fracture in 2010 (216 patients) and 2013 (196 patients) were similar in age, sex, Barthel Index, and a reduced Charlson Index, although there were more comorbidities in 2013. After implementation of the protocols, the detection of delirium, malnutrition, anemia, and electrolyte disturbances increased. A larger number of patients in 2013 were precribed intravenous iron (24% more) and osteoporosis treatment (61.3% more). The average stay was reduced by 45.3% and surgical delay by 29.4%, achieving better functional efficiency. The implementation of a clinical pathway in geriatric patients with hip fracture is useful to detect and treat complications at an early stage, and to reduce pre-operative and overall stay, all without a negative clinical or functional impact. Copyright © 2014 SEGG. Published by Elsevier Espana. All rights reserved.

The role of basement inheritance faults in the recent fracture system of the inner shelf around Alboran Island, Western Mediterranean

NASA Astrophysics Data System (ADS)

Maestro-González, A.; Bárcenas, P.; Vázquez, J. T.; Díaz-Del-Río, V.

2008-02-01

Fractures associated with volcanic rock outcrops on the inner shelf of Alboran Island, Western Mediterranean, were mapped on the basis of a side-scan sonar mosaic. Absolute maximum fracture orientation frequency is NW SE to NNW SSE, with several sub-maxima oriented NNE SSW, NE SW and ENE WSW. The origin of the main fracture systems in Neogene and Quaternary rocks of the Alboran Basin (south Spain) appears to be controlled by older structures, namely NE SW and WNW ESE to NW SE faults which cross-cut the basement. These faults, pre-Tortonian in origin, have been reactivated since the early Neogene in the form of strike-slip and extensional movements linked to the recent stress field in this area. Fracture analysis of volcanic outcrops on the inner continental shelf of Alboran Island suggests that the shelf has been deformed into a narrow shear zone limited by two NE SW-trending, sub-parallel high-angle faults, the main orientation and density of which have been influenced by previous WNW ESE to NW SE basement fractures.

Review of hydraulic fracture mapping using advanced accelerometer-based receiver systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.; Uhl, J.E.; Engler, B.P.

Hydraulic fracturing is an important tool for natural gas and oil exploitation, but its optimization has been impeded by an inability to observe how the fracture propagates and what its overall dimensions are. The few experiments in which fractures have been exposed through coring or mineback have shown that hydraulic fractures are complicated multi-stranded structures that may behave much differently than currently predicted by models. It is clear that model validation, fracture optimization, problem identification and solution, and field development have all been encumbered by the absence of any ground truth information on fracture behavior in field applications. The solutionmore » to this problem is to develop techniques to image the hydraulic fracture in situ from either the surface, the treatment well, or offset wells. Several diagnostic techniques have been available to assess individual elements of the fracture geometry, but most of these techniques have limitations on their usefulness. For example, tracers and temperature logs can only measure fracture height at the wellbore, well testing and production history matching provide a productive length which may or may not be different from the true fracture length, and tiltmeters can provide accurate information on azimuth and type of fracture (horizontal or vertical), but length and height can only be extracted from a non-unique inversion of the data. However, there is a method, the microseismic technique, which possesses the potential for imaging the entire hydraulic fracture and, more importantly, its growth history. This paper discusses application of advanced technology to the microseismic method in order to provide detailed accurate images of fractures and their growth processes.« less

Identifying fracture‐zone geometry using simulated annealing and hydraulic‐connection data

USGS Publications Warehouse

Day-Lewis, Frederick D.; Hsieh, Paul A.; Gorelick, Steven M.

2000-01-01

A new approach is presented to condition geostatistical simulation of high‐permeability zones in fractured rock to hydraulic‐connection data. A simulated‐annealing algorithm generates three‐dimensional (3‐D) realizations conditioned to borehole data, inferred hydraulic connections between packer‐isolated borehole intervals, and an indicator (fracture zone or background‐K bedrock) variogram model of spatial variability. We apply the method to data from the U.S. Geological Survey Mirror Lake Site in New Hampshire, where connected high‐permeability fracture zones exert a strong control on fluid flow at the hundred‐meter scale. Single‐well hydraulic‐packer tests indicate where permeable fracture zones intersect boreholes, and multiple‐well pumping tests indicate the degree of hydraulic connection between boreholes. Borehole intervals connected by a fracture zone exhibit similar hydraulic responses, whereas intervals not connected by a fracture zone exhibit different responses. Our approach yields valuable insights into the 3‐D geometry of fracture zones at Mirror Lake. Statistical analysis of the realizations yields maps of the probabilities of intersecting specific fracture zones with additional wells. Inverse flow modeling based on the assumption of equivalent porous media is used to estimate hydraulic conductivity and specific storage and to identify those fracture‐zone geometries that are consistent with hydraulic test data.

Structural controls on anomalous transport in fractured porous rock

NASA Astrophysics Data System (ADS)

Edery, Yaniv; Geiger, Sebastian; Berkowitz, Brian

2016-07-01

Anomalous transport is ubiquitous in a wide range of disordered systems, notably in fractured porous formations. We quantitatively identify the structural controls on anomalous tracer transport in a model of a real fractured geological formation that was mapped in an outcrop. The transport, determined by a continuum scale mathematical model, is characterized by breakthrough curves (BTCs) that document anomalous (or "non-Fickian") transport, which is accounted for by a power law distribution of local transition times ψ>(t>) within the framework of a continuous time random walk (CTRW). We show that the determination of ψ>(t>) is related to fractures aligned approximately with the macroscopic direction of flow. We establish the dominant role of fracture alignment and assess the statistics of these fractures by determining a concentration-visitation weighted residence time histogram. We then convert the histogram to a probability density function (pdf) that coincides with the CTRW ψ>(t>) and hence anomalous transport. We show that the permeability of the geological formation hosting the fracture network has a limited effect on the anomalous nature of the transport; rather, it is the fractures transverse to the flow direction that play the major role in forming the long BTC tail associated with anomalous transport. This is a remarkable result, given the complexity of the flow field statistics as captured by concentration transitions.

Geophysical investigation of liquefaction and surface ruptures at selected sites in Oklahoma post the 2016 Mw 5.8 Pawnee, OK earthquake

NASA Astrophysics Data System (ADS)

Kolawole, F.; Ismail, A. M.; Pickens, C. M.; Beckendorff, D.; Mayle, M. V.; Goussi, J. F.; Nyalugwe, V.; Aghayan, A.; Tim, S.; Atekwana, E. A.

2016-12-01

To date, the Mw 5.8 Pawnee, Oklahoma, earthquake on September 3, 2016 produced the largest moment release in the central and eastern United States, linked to saline waste water injection into the underlying formations. This earthquake occurred in a region of complex fault interactions, and typical of most of the earthquake activity in Oklahoma the earthquake ruptured a previously unknown left-lateral strike-slip fault striking 109°. Moreover, unlike the 2011 Mw 5.7 Prague, Oklahoma earthquake, the Pawnee earthquake produced surface deformation including fractures and liquefaction features. In this study, we use high resolution electrical resistivity, ground penetrating radar (GPR) and surface fracture mapping to image the zones of surface disruption. Our objective was to report some of the near-surface deformations that are associated with the recent earthquake and compare them with deep structures. We selected two sites for this study. We observed linear fractures and liquefaction at the first site which is 5 km away from the earthquake epicenter, while the second site, 7.5 km away from the epicenter, showed mostly curvilinear fractures. The resistivity and GPR sections showed indication of saturated sediments at about 2 m - 5 m below ground surface and settlement-sag structure within the liquefaction dominated area, and less saturated sediments in areas dominated by fractures only. GPS mapping of fractures at the first site revealed a pattern of en-echelon fractures oriented 93°-116°, sub-parallel to the orientation of the slip direction of the earthquake, while the fractures at the second site trend along the bank of a river meander. We infer that the liquefaction was enhanced by the occurrence of loose, wet, fluvial deposits of the Arkansas River flood plain and adequate near-surface pore pressure at the liquefaction dominated areas. Our results suggest the greater influence of surface morphological heterogeneity on the ruptures farther away from the epicenter, while the relationship between the deep structures, displacement kinematics and the linear fractures closer to the epicenter are unclear. We conclude that high resolution geophysical imaging can be used as a rapid response tool for evaluating areas susceptible to failure during earthquakes and can help improve hazard mitigation measures.

Innovative Methodology For Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobi, Rober

2007-03-28

This Topical Report (#6 of 9) consists of the figures 3.6-13 to (and including) 3.6-18 (and appropriate figure captions) that accompany the Final Technical Progress Report entitled: “Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin” for DOE/NETL Award DE-AC26-00NT40698.

FracPaQ: a MATLAB™ toolbox for the quantification of fracture patterns

NASA Astrophysics Data System (ADS)

Healy, David; Rizzo, Roberto; Farrell, Natalie; Watkins, Hannah; Cornwell, David; Gomez-Rivas, Enrique; Timms, Nick

2017-04-01

The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, shapes and spatial distributions often exhibit some kind of order. In detail, there may be relationships among the different fracture attributes e.g. small fractures dominated by one orientation, larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture patterns and fracture attributes. This presentation describes an open source toolbox to quantify fracture patterns, including distributions in fracture attributes and their spatial variation. Software has been developed to quantify fracture patterns from 2-D digital images, such as thin section micrographs, geological maps, outcrop or aerial photographs or satellite images. The toolbox comprises a suite of MATLAB™ scripts based on published quantitative methods for the analysis of fracture attributes: orientations, lengths, intensity, density and connectivity. An estimate of permeability in 2-D is made using a parallel plate model. The software provides an objective and consistent methodology for quantifying fracture patterns and their variations in 2-D across a wide range of length scales. Our current focus for the application of the software is on quantifying crack and fracture patterns in and around fault zones. There is a large body of published work on the quantification of relatively simple joint patterns, but fault zones present a bigger, and arguably more important, challenge. The methods presented are inherently scale independent, and a key task will be to analyse and integrate quantitative fracture pattern data from micro- to macro-scales. New features in this release include multi-scale analyses based on a wavelet method to look for scale transitions, support for multi-colour traces in the input file processed as separate fracture sets, and combining fracture traces from multiple 2-D images to derive the statistically equivalent 3-D fracture pattern expressed as a 2nd rank crack tensor.

Spectroscopic mapping of the white horse alunite deposit, Marysvale volcanic field, Utah: Evidence of a magmatic component

USGS Publications Warehouse

Rockwell, B.W.; Cunningham, C.G.; Breit, G.N.; Rye, R.O.

2006-01-01

Previous studies have demonstrated that the replacement alunite deposits just north of the town of Marysvale, Utah, USA, were formed primarily by low-temperature (100??-170?? C), steam-heated processes near the early Miocene paleoground surface, immediately above convecting hydrothermal plumes. Pyrite-bearing propylitically altered rocks occur mainly beneath the steam-heated alunite and represent the sulfidized feeder zone of the H2S-dominated hydrothermal fluids, the oxidation of which at higher levels led to the formation of the alunite. Maps of surface mineralogy at the White Horse deposit generated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used in conjunction with X-ray diffraction studies of field samples to test the accuracy and precision of AVIRIS-based mineral mapping of altered rocks and demonstrate the utility of spectroscopic mapping for ore deposit characterization. The mineral maps identified multiple core zones of alunite that grade laterally outward to kaolinite. Surrounding the core zones are dominantly propylitically altered rocks containing illite, montmorillonite, and chlorite, with minor pyrite, kaolinite, gypsum, and remnant potassium feldspar from the parent rhyodacitic ash-flow tuff. The AVIRIS mapping also identified fracture zones expressed by ridge-forming selvages of quartz + dickite + kaolinite that form a crude ring around the advanced argillic core zones. Laboratory analyses identified the aluminum phosphate-sulfate (APS) minerals woodhouseite and svanbergite in one sample from these dickite-bearing argillic selvages. Reflectance spectroscopy determined that the outer edges of the selvages contain more dickite than do the medial regions. The quartz + dickite ?? kaolinite ?? APS-mineral selvages demonstrate that fracture control of replacement processes is more prevalent away from the advanced argillic core zones. Although not exposed at the White Horse deposit, pyrophyllite ?? ordered illite was identified using AVIRIS in localized, superimposed conduits within propylitically altered rocks in nearby alteration systems of similar age and genesis that have been eroded to deeper levels. The fracture zones bearing pyrophyllite, illite, dickite, natroalunite, and/or APS minerals indicate a magmatic component in the dominantly steam-heated system. ?? 2006 Society of Economic Geologists, Inc.

Alpha-adrenergic blocker mediated osteoblastic stem cell differentiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Yoon Jung; Lee, Jue Yeon; Research Center, Nano Intelligent Biomedical Engineering Corporation

Highlights: Black-Right-Pointing-Pointer Doxazocin directly up-regulated bone metabolism at a low dose. Black-Right-Pointing-Pointer Doxazocin induced osteoblastic stem cell differentiation without affecting cell proliferation. Black-Right-Pointing-Pointer This osteogenic stem cell differentiation is mediated by ERK-signal dependent pathway. -- Abstract: Recent researches have indicated a role for antihypertensive drugs including alpha- or beta-blockers in the prevention of bone loss. Some epidemiological studies reported the protective effects of those agents on fracture risk. However, there is limited information on the association with those agents especially at the mechanism of action. In the present study, we investigated the effects of doxazosin, an alpha-blocker that is clinicallymore » used for the treatment of benign prostatic hyperplasia (BPH) along with antihypertensive medication, on the osteogenic stem cell differentiation. We found that doxazosin increased osteogenic differentiation of human mesenchymal stem cells, detected by Alizarin red S staining and calcein. Doxazosin not only induced expression of alkaline phosphatase, type I collagen, osteopontin, and osteocalcin, it also resulted in increased phosphorylation of extracellular signal-regulated kinase (ERK1/2), a MAP kinase involved in osteoblastic differentiation. Treatment with U0126, a MAP kinase inhibitor, significantly blocked doxazosin-induced osteoblastic differentiation. Unrelated to activation of osteogenic differentiation by doxazosin, we found that there were no significant changes in adipogenic differentiation or in the expression of adipose-specific genes, including peroxisome proliferator-activated receptor {gamma}, aP2, or LPL. In this report, we suggest that doxazosin has the ability to increase osteogenic cell differentiation via ERK1/2 activation in osteogenic differentiation of adult stem cells, which supports the protective effects of antihypertensive drug on fracture risk and according to our data doxazosin might be useful for application in the field of bone metabolism.« less

Hydraulic fracturing water use variability in the United States and potential environmental implications

PubMed Central

Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

2015-01-01

Abstract Until now, up‐to‐date, comprehensive, spatial, national‐scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale‐gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection‐induced earthquakes. PMID:26937056

Hydraulic fracturing water use variability in the United States and potential environmental implications

USGS Publications Warehouse

Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

2015-01-01

Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

Influence of Landscape Coverage on Measuring Spatial and Length Properties of Rock Fracture Networks: Insights from Numerical Simulation

NASA Astrophysics Data System (ADS)

Cao, Wenzhuo; Lei, Qinghua

2018-01-01

Natural fractures are ubiquitous in the Earth's crust and often deeply buried in the subsurface. Due to the difficulty in accessing to their three-dimensional structures, the study of fracture network geometry is usually achieved by sampling two-dimensional (2D) exposures at the Earth's surface through outcrop mapping or aerial photograph techniques. However, the measurement results can be considerably affected by the coverage of forests and other plant species over the exposed fracture patterns. We quantitatively study such effects using numerical simulation. We consider the scenario of nominally isotropic natural fracture systems and represent them using 2D discrete fracture network models governed by fractal and length scaling parameters. The groundcover is modelled as random patches superimposing onto the 2D fracture patterns. The effects of localisation and total coverage of landscape patches are further investigated. The fractal dimension and length exponent of the covered fracture networks are measured and compared with those of the original non-covered patterns. The results show that the measured length exponent increases with the reduced localisation and increased coverage of landscape patches, which is more evident for networks dominated by very large fractures (i.e. small underlying length exponent). However, the landscape coverage seems to have a minor impact on the fractal dimension measurement. The research findings of this paper have important implications for field survey and statistical analysis of geological systems.

Relationship between the Mediterranean dietary pattern and musculoskeletal health in children, adolescents, and adults: systematic review and evidence map

PubMed Central

Craig, Jean V; Bunn, Diane K; Hayhoe, Richard P; Appleyard, Will O; Lenaghan, Elizabeth A; Welch, Ailsa A

2017-01-01

Context: An understanding of the modifiable effects of diet on bone and skeletal muscle mass and strength over the life course will help inform strategies to reduce age-related fracture risk. The Mediterranean diet is rich in nutrients that may be important for optimal musculoskeletal health. Objective: The aim of this systematic review was to investigate the relationship between a Mediterranean diet and musculoskeletal outcomes (fracture, bone density, osteoporosis, sarcopenia) in any age group. Data Sources: Ten electronic databases were searched. Study Selection: Randomized controlled trials and prospective cohort studies that investigated a traditional Mediterranean diet, published in any language, were eligible. Studies using other designs or other definitions of the Mediterranean diet were collated separately in an evidence map. Data Extraction: Details on study design, methods, population, dietary intervention or exposure, length of follow-up, and effect on or association with musculoskeletal outcomes were extracted. Results: The search yielded 1738 references. Data from eligible randomized controlled trials (n = 0) and prospective cohort studies (n = 3) were synthesized narratively by outcome for the systematic review. Two of these studies reported on hip fracture incidence, but results were contradictory. A third study found no association between the Mediterranean diet and sarcopenia incidence. Conclusions: Overall, the systematic review and evidence map demonstrate a lack of research to understand the relationship between the Mediterranean diet and musculoskeletal health in all ages. Systematic Review Registration: PROSPERO registration number IDCRD42016037038. PMID:29028268

Analysis of Geothermal Pathway in the Metamorphic Area, Northeastern Taiwan

NASA Astrophysics Data System (ADS)

Wang, C.; Wu, M. Y.; Song, S. R.; Lo, W.

2016-12-01

A quantitative measure by play fairway analysis in geothermal energy development is an important tool that can present the probability map of potential resources through the uncertainty studies in geology for early phase decision making purpose in the related industries. While source, pathway, and fluid are the three main geologic factors in traditional geothermal systems, identifying the heat paths is critical to reduce drilling cost. Taiwan is in East Asia and the western edge of Pacific Ocean, locating on the convergent boundary of Eurasian Plate and Philippine Sea Plate with many earthquake activities. This study chooses a metamorphic area in the western corner of Yi-Lan plain in northeastern Taiwan with high geothermal potential and several existing exploration sites. Having high subsurface temperature gradient from the mountain belts, and plenty hydrologic systems through thousands of millimeters annual precipitation that would bring up heats closer to the surface, current geothermal conceptual model indicates the importance of pathway distribution which affects the possible concentration of extractable heat location. The study conducts surface lineation analysis using analytic hierarchy process to determine weights among various fracture types for their roles in geothermal pathways, based on the information of remote sensing data, published geologic maps and field work measurements, to produce regional fracture distribution probability map. The results display how the spatial distribution of pathways through various fractures could affect geothermal systems, identify the geothermal plays using statistical data analysis, and compare against the existing drilling data.

A comparative study evaluating the efficacy of IS_MAP04 with IS900 and IS_MAP02 as a new diagnostic target for the detection of Mycobacterium avium subspecies paratuberculosis from bovine faeces.

PubMed

de Kruijf, Marcel; Govender, Rodney; Yearsley, Dermot; Coffey, Aidan; O'Mahony, Jim

2017-05-01

The aim of this study was to investigate the efficacy of IS_MAP04 as a potential new diagnostic quantitative PCR (qPCR) target for the detection of Mycobacterium avium subspecies paratuberculosis from bovine faeces. IS_MAP04 primers were designed and tested negative against non-MAP strains. The detection limit of IS_MAP04 qPCR was evaluated on different MAP K-10 DNA concentrations and on faecal samples spiked with different MAP K-10 cell dilutions. A collection of 106 faecal samples was analysed and the efficacy of IS_MAP04 was statistically compared with IS900 and IS_MAP02. The detection limits observed for IS_MAP04 and IS900 on MAP DNA was 34 fg and 3.4 fg respectively. The detection limit of MAP from inoculated faecal samples was 10 2 CFU/g for both IS_MAP04 and IS900 targets and a detection limit of 10 2 CFU/g was also achieved with a TaqMan qPCR targeting IS_MAP04. The efficacy of IS_MAP04 to detect positive MAP faecal samples was 83.0% compared to 85.8% and 83.9% for IS900 and IS_MAP02 respectively. Strong kappa agreements were observed between IS_MAP04 and IS900 (κ=0.892) and between IS_MAP04 and IS_MAP02 (κ=0.897). As a new molecular target, IS_MAP04 showed that the detection limit was comparable to IS900 to detect MAP from inoculated faecal material. The MAP detection efficacy of IS_MAP04 from naturally infected faecal samples proved to be relatively comparable to IS_MAP02, but yielded efficacy results slightly less than IS900. Moreover, IS_MAP04 could be of significant value when used in duplex or multiplex qPCR assays. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface faulting near Livermore, California, associated with the January 1980 earthquakes

USGS Publications Warehouse

Bonilla, Manuel G.; Lienkaemper, James J.; Tinsley, John C.

1980-01-01

The earthquakes of 24 January (Ms 5.8) 1980 north of Livermore, California, and 26 January (Ms 5.2), were accompanied by surface faulting in the Greenville fault zone and apparently in the Las Positas fault zone also. The surface faulting was discontinuous and of small displacement. The main rupture within the Greenville fault zone trended about N.38°W. It was at least 4.2 km long and may have extended southward to Interstate Highway 580, giving a possible length of 6.2 km; both of these lengths included more gaps than observed surface rupture. Maximum displacements measured by us were about 25 mm of right slip (including afterslip through 28 January); vertical components of as much as 50 mm were seen locally, but these included gravity effects of unknown amount. The main break within the Greenville fault zones is very close to a fault strand mapped by Herd (1977, and unpublished data). A subsidiary break within the Greenville fault zone was about 0.5 km. long, had a general trend of N.46°W., and lay 0.12 to 0.25 km east of the main break. It was characterized by extension of as much as 40 mm and right slip of as much as 20 mm. This break was no more than 25 m from a fault mapped by Herd (unpublished data). Another break within the Greenville fault zone lay about 0.3 km southwest of the projection of the main break and trended about N33°W. It was at least 0.3 km long and showed mostly extension, but at several places a right-lateral component (up to 5 mm) was seen. This break was 80 to 100 m from a strand of the Greenville fault mapped by Herd (1977). Extensional fractures within the Greenville fault zone on the frontage roads north and south of Interstate Highway 580 may be related to regional extension or other processes, but do not seem to have resulted from faulting of the usual kind. One exception in this group is a fracture at the east side of Livermore valley which showed progressive increase in right-lateral displacement in February and March, 1980, and is directly on the projection of a fault in the Greenville fault zone mapped by Herd (1977). A group of more than 20 extensional fractures in Laughlin Road 1 km north of Interstate 580 probably are related to small tectonic displacements on faults in the Greenville fault zone. They are adjacent and parallel to two faults mapped by Herd (1977), are diagonal to the road, and most of them developed between 25 and 29 January, a period that included the Ms 5.2 shock of 26 January. Observations at two locations indicate tectonic displacement on the Las Positas fault zone as mapped by Herd (1977). At Vasco Road a prominent break on a strand of the fault showed about 0.5 mm of left-lateral strike slip on 7 February. An alinement array across this and other fractures at the locality indicates about 6 mm of left-lateral displacement occurred between 21 February and 26 March. On Tesla Road several right-stepping fractures, one of which showed 1.5 mm of left-lateral strike slip, lie on or close tp previously mapped strands of the Las Positas fault zone. The evidence at these two localities indicates that tectonic surface displacement occurred along at least 1.1 km of the Las Positas fault zone.

Hydraulic Fracturing and Production Optimization in Eagle Ford Shale Using Coupled Geomechanics and Fluid Flow Model

NASA Astrophysics Data System (ADS)

Suppachoknirun, Theerapat; Tutuncu, Azra N.

2017-12-01

With increasing production from shale gas and tight oil reservoirs, horizontal drilling and multistage hydraulic fracturing processes have become a routine procedure in unconventional field development efforts. Natural fractures play a critical role in hydraulic fracture growth, subsequently affecting stimulated reservoir volume and the production efficiency. Moreover, the existing fractures can also contribute to the pressure-dependent fluid leak-off during the operations. Hence, a reliable identification of the discrete fracture network covering the zone of interest prior to the hydraulic fracturing design needs to be incorporated into the hydraulic fracturing and reservoir simulations for realistic representation of the in situ reservoir conditions. In this research study, an integrated 3-D fracture and fluid flow model have been developed using a new approach to simulate the fluid flow and deliver reliable production forecasting in naturally fractured and hydraulically stimulated tight reservoirs. The model was created with three key modules. A complex 3-D discrete fracture network model introduces realistic natural fracture geometry with the associated fractured reservoir characteristics. A hydraulic fracturing model is created utilizing the discrete fracture network for simulation of the hydraulic fracture and flow in the complex discrete fracture network. Finally, a reservoir model with the production grid system is used allowing the user to efficiently perform the fluid flow simulation in tight formations with complex fracture networks. The complex discrete natural fracture model, the integrated discrete fracture model for the hydraulic fracturing, the fluid flow model, and the input dataset have been validated against microseismic fracture mapping and commingled production data obtained from a well pad with three horizontal production wells located in the Eagle Ford oil window in south Texas. Two other fracturing geometries were also evaluated to optimize the cumulative production and for the three wells individually. Significant reduction in the production rate in early production times is anticipated in tight reservoirs regardless of the fracturing techniques implemented. The simulations conducted using the alternating fracturing technique led to more oil production than when zipper fracturing was used for a 20-year production period. Yet, due to the decline experienced, the differences in cumulative production get smaller, and the alternating fracturing is not practically implementable while field application of zipper fracturing technique is more practical and widely used.

Using the Bongwana natural CO2 release to understand leakage processes and develop monitoring

NASA Astrophysics Data System (ADS)

Jones, David; Johnson, Gareth; Hicks, Nigel; Bond, Clare; Gilfillan, Stuart; Kremer, Yannick; Lister, Bob; Nkwane, Mzikayise; Maupa, Thulani; Munyangane, Portia; Robey, Kate; Saunders, Ian; Shipton, Zoe; Pearce, Jonathan; Haszeldine, Stuart

2016-04-01

Natural CO2 leakage along the Bongwana Fault in South Africa is being studied to help understand processes of CO2 leakage and develop monitoring protocols. The Bongwana Fault crops out over approximately 80 km in KwaZulu-Natal province, South Africa. In outcrop the fault is expressed as a broad fracture corridor in Dwyka Tillite, with fractures oriented approximately N-S. Natural emissions of CO2 occur at various points along the fault, manifest as travertine cones and terraces, bubbling in the rivers and as gas fluxes through soil. Exposed rock outcrop shows evidence for Fe-staining around fractures and is locally extensively kaolinitised. The gas has also been released through a shallow water well, and was exploited commercially in the past. Preliminary studies have been carried out to better document the surface emissions using near surface gas monitoring, understand the origin of the gas through major gas composition and stable and noble gas isotopes and improve understanding of the structural controls on gas leakage through mapping. In addition the impact of the leaking CO2 on local water sources (surface and ground) is being investigated, along with the seismic activity of the fault. The investigation will help to build technical capacity in South Africa and to develop monitoring techniques and plans for a future CO2 storage pilot there. Early results suggest that CO2 leakage is confined to a relatively small number of spatially-restricted locations along the weakly seismically active fault. Fracture permeability appears to be the main method by which the CO2 migrates to the surface. The bulk of the CO2 is of deep origin with a minor contribution from near surface biogenic processes as determined by major gas composition. Water chemistry, including pH, DO and TDS is notably different between CO2-rich and CO2-poor sites. Soil gas content and flux effectively delineates the fault trace in active leakage sites. The fault provides an effective testing ground for field-based monitoring with results to date indicating the methods and technologies tested successfully detect leaking CO2. Further work will investigate the source of the CO2 and attempt to quantify CO2 flux rates and detection thresholds.

Viral Predation and Host Immunity Structure Microbial Communities in a Terrestrial Deep Subsurface, Hydraulically Fractured Shale System

NASA Astrophysics Data System (ADS)

Daly, R. A.; Mouser, P. J.; Trexler, R.; Wrighton, K. C.

2014-12-01

Despite a growing appreciation for the ecological role of viruses in marine and gut systems, little is known about their role in the terrestrial deep (> 2000 m) subsurface. We used assembly-based metagenomics to examine the viral component in fluids from hydraulically fractured Marcellus shale gas wells. Here we reconstructed microbial and viral genomes from samples collected 7, 82, and 328 days post fracturing. Viruses accounted for 4.14%, 0.92% and 0.59% of the sample reads that mapped to the assembly. We identified 6 complete, circularized viral genomes and an additional 92 viral contigs > 5 kb with a maximum contig size of 73.6 kb. A BLAST comparison to NCBI viral genomes revealed that 85% of viral contigs had significant hits to the viral order Caudovirales, with 43% of sequences belonging to the family Siphoviridae, 38% to Myoviridae, and 12% to Podoviridae. Enrichment of Caudovirales viruses was supported by a large number of predicted proteins characteristic of tailed viruses including terminases (TerL), tape measure, tail formation, and baseplate related proteins. The viral contigs included evidence of lytic and temperate lifestyles, with the 7 day sample having the greatest number of detected lytic viruses. Notably in this sample, the most abundant virus was lytic and its inferred host, a member of the Vibrionaceae, was not detected at later time points. Analyses of CRISPR sequences (a viral and foreign DNA immune system in bacteria and archaea), linked 18 viral contigs to hosts. CRISPR linkages increased through time and all bacterial and archaeal genomes recovered in the final time point had genes for CRISPR-mediated viral defense. The majority of CRISPR sequences linked phage genomes to several Halanaerobium strains, which are the dominant and persisting members of the community inferred to be responsible for carbon and sulfur cycling in these shales. Network analysis revealed that several viruses were present in the 82 and 328 day samples; this viral persistence is consistent with concomitant temporal stability in geochemistry and microbial community composition. Our findings suggest that after a disturbance (hydraulic fracturing) viral predation and host immunity is an important controller of microbial community structure, metabolism, and thus biogeochemical cycling in the deep subsurface.

Enceladus Plume Activity Consistent with Eruptions from Sources within a Thin Shell

NASA Astrophysics Data System (ADS)

Hurford, Terry; Spitale, Joseph N.; Rhoden, Alyssa R.; Henning, Wade

2017-10-01

Enceladus is a small (radius 250 km) moon that orbits Saturn between the moons Mimas and Tethys with a period of 1.37 days. A 2:1 mean motion resonance with the moon Dione, which orbits just beyond Tethys, excites its orbital eccentricity to the observed value of 0.0047, which in turn produces periodic tidal stress on the surface.In 2005, Cassini detected the eruption of material from warm regions, which correlated with the large Tiger Stripe fractures near the south pole of Enceladus. A 2007 analysis of tidal stress postulated that the eruptive activity might be linked to tidal tension across these fractures and predicted that activity should vary on the orbital timescale such that greatest activity should be observed near apocenter (Hurford et al., 2007). In 2013, results from analysis of Cassini’s Visual and Infrared Map- ping Spectrometer (VIMS) data detected variability of the erupting material in the orbital cycle and qualitatively confirmed the predictions of variable activity from 2007 (Hedman et al., 2013; Hurford et al. 2007).Since then, work has been done to refine models for tidal control of plume activity. Nimmo et al. (2014) found that the plume activity could track the fraction of fractures under tension, but required a ~5 hr lag in Enceladus’ tidal response. This lag seemed plausible in a 24km ice shell. Behounkova et al. (2105) confirmed this result with a slightly improved model that linked tidal activity to normalize average tensile stress on the fracture.In this work, we illustrate how reservoir depth combines with a lag in tidal response to mimic larger delays in tidal activity. Taking into account the depth of the volatile reservoir, we find that the response of Enceladus to tidal deformation needs only be ~3 hrs and is more consistent with eruptions from a thin ice shell (≤10 km). This result is more consistent with recent revisions in ice shell thickness (Iess et al., 2014; Thomas et al., 2016).Hurford et al., 2007, Nature 447, 292-294. Hedman et al, 2013, Nature 500, 182-184. Nimmo et al, 2014, The Astronomical Journal 148. Behounkova et al., 2015, Nature Geoscience 8, 601-604. Iess et al., 2014, Science 344, 78-80. Thomas et al., 2016, Icarus 264, 37-47.

"Blind spots" in forensic autopsy: improved detection of retrobulbar hemorrhage and orbital lesions by postmortem computed tomography (PMCT).

PubMed

Flach, P M; Egli, T C; Bolliger, S A; Berger, N; Ampanozi, G; Thali, M J; Schweitzer, W

2014-09-01

The purpose of this study was to correlate the occurrence of retrobulbar hemorrhage (RBH) with mechanism of injury, external signs and autopsy findings to postmortem computed tomography (PMCT). Six-teen subjects presented with RBH and underwent PMCT, external inspection and conventional autopsy. External inspection was evaluated for findings of the bulbs, black eye, raccoon eyes and Battle's sign. Fractures of the viscerocranium, orbital lesions and RBH were evaluated by PMCT. Autopsy and PMCT was evaluated for orbital roof and basilar skull fracture. The leading manner of death was accident with central regulatory failure in cases of RBH (31.25%). Imaging showed a high sensitivity in detection of orbital roof and basilar skull fractures (100%), but was less specific compared to autopsy. Volume of RBH (0.1-2.4ml) correlated positively to the presence of Battle's sign (p<0.06) and the postmortem interval. Ecchymosis on external inspection correlated with RBH. There was a statistical significant correlation between bulbar lesion and RBH. Orbital roof fracture count weakly correlated with the total PMCT derived RBH volume. Maxillary hemosinus correlated to maxillary fractures, but not to RBH. RBH are a specific finding in forensically relevant head trauma. PMCT is an excellent tool in detecting and quantifying morphological trauma findings particularly in the viscerocranium, one of the most relevant "blind spots" of classic autopsy. PMCT was superior in detecting osseous lesions, scrutinizing autopsy as the gold standard. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Hip fracture in the elderly: a re-analysis of the EPIDOS study with causal Bayesian networks.

PubMed

Caillet, Pascal; Klemm, Sarah; Ducher, Michel; Aussem, Alexandre; Schott, Anne-Marie

2015-01-01

Hip fractures commonly result in permanent disability, institutionalization or death in elderly. Existing hip-fracture predicting tools are underused in clinical practice, partly due to their lack of intuitive interpretation. By use of a graphical layer, Bayesian network models could increase the attractiveness of fracture prediction tools. Our aim was to study the potential contribution of a causal Bayesian network in this clinical setting. A logistic regression was performed as a standard control approach to check the robustness of the causal Bayesian network approach. EPIDOS is a multicenter study, conducted in an ambulatory care setting in five French cities between 1992 and 1996 and updated in 2010. The study included 7598 women aged 75 years or older, in which fractures were assessed quarterly during 4 years. A causal Bayesian network and a logistic regression were performed on EPIDOS data to describe major variables involved in hip fractures occurrences. Both models had similar association estimations and predictive performances. They detected gait speed and mineral bone density as variables the most involved in the fracture process. The causal Bayesian network showed that gait speed and bone mineral density were directly connected to fracture and seem to mediate the influence of all the other variables included in our model. The logistic regression approach detected multiple interactions involving psychotropic drug use, age and bone mineral density. Both approaches retrieved similar variables as predictors of hip fractures. However, Bayesian network highlighted the whole web of relation between the variables involved in the analysis, suggesting a possible mechanism leading to hip fracture. According to the latter results, intervention focusing concomitantly on gait speed and bone mineral density may be necessary for an optimal prevention of hip fracture occurrence in elderly people.

Probabilistic pipe fracture evaluations for leak-rate-detection applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, S.; Ghadiali, N.; Paul, D.

1995-04-01

Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crackmore » size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.« less

Nonlinear Structural Health Monitoring of the Responsive Space Satellite Systems Using Magneto Elastic Active Sensors (MEAS)

DTIC Science & Technology

2011-11-30

detection of fatigue damage at early stage, well before onset of fracture and crack development. Analytical and numerical models of MEAS and MMI are...stage, well before onset of fracture and crack development. Analytical and numerical models of MEAS and MMI are suggested. Finally, MEAS capability...47  2.4.1  Far-Field Crack Detection

Influence of Natural Fractures Cohesive Properties on Geometry of Hydraulic Fracture Networks

NASA Astrophysics Data System (ADS)

Gonzalez-Chavez, M. A.; Dahi Taleghani, A.; Puyang, P.

2014-12-01

An integrated modeling methodology is proposed to analyze hydraulic fracturing jobs in the presence of the natural fracture network in the formation. A propagating hydraulic fracture may arrest, cross, or diverts into a preexisting natural crack depending on fracture properties of rock and magnitude and direction of principal rock stresses. Opening of natural fractures during fracturing treatment could define the effectiveness of the stimulation technique. Here, we present an integrated methodology initiated with lab scale fracturing properties using Double Cantilever Beam tests (DCB) to determine cohesive properties of rock and natural fractures. We used cohesive finite element models to reproduce laboratory results to verify the numerical model for the interaction of the hydraulic fracture and individual cemented natural fractures. Based on the initial investigations, we found out that distribution of pre-existing natural fractures could play a significant role in the final geometry of the induced fracture network; however in practice, there is not much information about the distribution of natural fractures in the subsurface due to the limited access. Hence, we propose a special optimization scheme to generate natural fracture geometry from the location of microseismic events. Accordingly, the criteria of evaluating the fitness of natural fracture realizations is defined as the total minimum distance squares of all microseismic events, which is the sum of minimum square distance for all microseismic events. Moreover, an additional constraint in this problem is that we need to set a minimum distance between fracture grids. Using generated natural fracture realizations, forward field-scale simulations are implemented using cohesive finite element analysis to find the best match with the recorded bottomhole pressure. To show the robustness of the proposed workflow for real field problem, we implemented this technique on available data from several well Chicontepec basin to forecast post-treatment production rate. Our results show a constructive approach to integrate microseismic maps with lab mechanical measurements and bottomhole pressure to estimate the geometry of induced fracture network in the subsurface which does not suffer from any limiting assumption about fracture geometries.

Induced seismicity response of hydraulic fracturing: results of a multidisciplinary monitoring at the Wysin site, Poland.

PubMed

López-Comino, J A; Cesca, S; Jarosławski, J; Montcoudiol, N; Heimann, S; Dahm, T; Lasocki, S; Gunning, A; Capuano, P; Ellsworth, W L

2018-06-05

Shale oil and gas exploitation by hydraulic fracturing experienced a strong development worldwide over the last years, accompanied by a substantial increase of related induced seismicity, either consequence of fracturing or wastewater injection. In Europe, unconventional hydrocarbon resources remain underdeveloped and their exploitation controversial. In UK, fracturing operations were stopped after the M w 2.3 Blackpool induced earthquake; in Poland, operations were halted in 2017 due to adverse oil market conditions. One of the last operated well at Wysin, Poland, was monitored independently in the framework of the EU project SHEER, through a multidisciplinary system including seismic, water and air quality monitoring. The hybrid seismic network combines surface mini-arrays, broadband and shallow borehole sensors. This paper summarizes the outcomes of the seismological analysis of these data. Shallow artificial seismic noise sources were detected and located at the wellhead active during the fracturing stages. Local microseismicity was also detected, located and characterised, culminating in two events of M w 1.0 and 0.5, occurring days after the stimulation in the vicinity of the operational well, but at very shallow depths. A sharp methane peak was detected ~19 hours after the M w 0.5 event. No correlation was observed between injected volumes, seismicity and groundwater parameters.

Analysis of ERTS-1 imagery and its application to evaluation of Wyoming's natural resources

NASA Technical Reports Server (NTRS)

Houston, R. S. (Principal Investigator); Marrs, R. W.

1973-01-01

The author has identified the following significant results. Significant results of the Wyoming ERTS-1 investigation during the first six months (July-December 1972) included: (1) successful segregation of Precambrian metasedimentary/metavolcanic rocks from igneous rocks, (2) discovery of iron formation within the metasedimentary sequence, (3) mapping of previously unreported tectonic elements of major significance, (4) successful mapping of large scale fracture systems of the Wind River Mountains, (5) successful distinction of some metamorphic, igneous, and sedimentary lithologies by color additive viewing, (6) mapping of large scale glacial features, and (7) development of techniques for mapping small urban areas.

Analysis of ERTS-1 imagery of Wyoming and its application to evaluation of Wyoming's natural resources

NASA Technical Reports Server (NTRS)

Marrs, R. W.

1973-01-01

The author has identified the following significant results. Significant results of the Wyoming investigation during the first six months include: (1) successful segregation of Precambrian metasedimentary/metavolcanic rocks from igneous rocks; (2) discovery of iron formation within the metasedimentary sequence; (3) mapping of previously unreported tectonic elements of major significance; (4) successful mapping of large scale fractures of the Wind River Mountains; (5) sucessful distinction of some metamorphic, igneous, and sedimentary lithologies by color-additive viewing of ERTS images; (6) mapping and interpretation of glacial features in western Wyoming; and (7) development of techniques for mapping small urban areas.

Investigating the Capabilities of Ground Penetrating Radar for Imaging Shallow Experimental Fractures

NASA Astrophysics Data System (ADS)

Dogan, M.; Moysey, S. M.; Murdoch, L. C.; Denison, J. L. S.; Ahmadian, M.

2017-12-01

We have used ground penetrating radar (GPR) to image fractures formed in shallow sediments as a result of high-pressure injection. Understanding fracture formation and behavior is important for a variety of reasons, ranging from validating fracture formation theories to characterizing fracture networks induced for enhancing recovery schemes in low permeability rocks. GPR is a high resolution geophysical method that is sensitive to electromagnetic property changes in the subsurface. The resolution of GPR is, however, typically on the order of ¼ of the wavelength, which for the 900MHz GPR data is on the order of 2-5cm. Thus it was not clear prior to the experiment whether it would be possible for GPR to image the fractures formed during the injection. We found that the GPR was indeed able to image the fractures very well as they evolved through time. Over the course of the experiment, we were able to collect pseudo-3D data that allowed us to monitor the growth of the fracture over time. The experiment was also repeated for different injection materials to examine how the fill in the fractures impacts the GPR signal. From the GPR data we are able to reconstruct the approximate three-dimensional shape of the facture over time. At the end of the experiment, the experimental cells were trenched so that the actual fracture distribution could be mapped. Overall, the GPR interpretation showed reasonable agreement with what we could observed in the trenches. The experimental results suggest that GPR characterization of fractures is feasible.

Structure of pseudotachylyte vein systems as a key to co-seismic rupture dynamics: the case of Gavilgarh-Tan Shear Zone, central India

NASA Astrophysics Data System (ADS)

Chattopadhyay, A.; Bhattacharjee, D.; Mukherjee, S.

2014-04-01

The secondary fractures associated with a major pseudotachylyte-bearing fault vein in the sheared aplitic granitoid of the Proterozoic Gavilgarh-Tan Shear Zone in central India are mapped at the outcrop scale. The fracture maps help to identify at least three different types of co-seismic ruptures, e.g., X-X', T1 and T2, which characterize sinistral-sense shearing of rocks, confined between two sinistral strike-slip faults slipping at seismic rate. From the asymmetric distribution of tensile fractures around the sinistral-sense fault vein, the direction of seismic rupture propagation is predicted to have occurred from west-southwest to east-northeast, during an ancient (Ordovician?) earthquake. Calculations of approximate co-seismic displacement on the faults and seismic moment ( M 0) of the earthquake are attempted, following the methods proposed by earlier workers. These estimates broadly agree to the findings from other studied fault zones (e.g., Gole Larghe Fault zone, Italian Alps). This study supports the proposition by some researchers that important seismological information can be extracted from tectonic pseudotachylytes of all ages, provided they are not reworked by subsequent tectonic activity.

Curtain eruptions from Enceladus' south-polar terrain.

PubMed

Spitale, Joseph N; Hurford, Terry A; Rhoden, Alyssa R; Berkson, Emily E; Platts, Symeon S

2015-05-07

Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called 'tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the surrounding terrain. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work examined those newer data sets and used triangulation of discrete jets to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions.

Curtain eruptions from Enceladus' south-polar terrain

NASA Astrophysics Data System (ADS)

Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R.; Berkson, Emily E.; Platts, Symeon S.

2015-05-01

Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called `tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the surrounding terrain. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work examined those newer data sets and used triangulation of discrete jets to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions.

Crack Growth Prediction Methodology for Multi-Site Damage: Layered Analysis and Growth During Plasticity

NASA Technical Reports Server (NTRS)

James, Mark Anthony

1999-01-01

A finite element program has been developed to perform quasi-static, elastic-plastic crack growth simulations. The model provides a general framework for mixed-mode I/II elastic-plastic fracture analysis using small strain assumptions and plane stress, plane strain, and axisymmetric finite elements. Cracks are modeled explicitly in the mesh. As the cracks propagate, automatic remeshing algorithms delete the mesh local to the crack tip, extend the crack, and build a new mesh around the new tip. State variable mapping algorithms transfer stresses and displacements from the old mesh to the new mesh. The von Mises material model is implemented in the context of a non-linear Newton solution scheme. The fracture criterion is the critical crack tip opening displacement, and crack direction is predicted by the maximum tensile stress criterion at the crack tip. The implementation can accommodate multiple curving and interacting cracks. An additional fracture algorithm based on nodal release can be used to simulate fracture along a horizontal plane of symmetry. A core of plane strain elements can be used with the nodal release algorithm to simulate the triaxial state of stress near the crack tip. Verification and validation studies compare analysis results with experimental data and published three-dimensional analysis results. Fracture predictions using nodal release for compact tension, middle-crack tension, and multi-site damage test specimens produced accurate results for residual strength and link-up loads. Curving crack predictions using remeshing/mapping were compared with experimental data for an Arcan mixed-mode specimen. Loading angles from 0 degrees to 90 degrees were analyzed. The maximum tensile stress criterion was able to predict the crack direction and path for all loading angles in which the material failed in tension. Residual strength was also accurately predicted for these cases.

Habitat characterization of the Vema Fracture Zone and Puerto Rico Trench

NASA Astrophysics Data System (ADS)

Devey, C. W.; Augustin, N.; Brandt, A.; Brenke, N.; Köhler, J.; Lins, L.; Schmidt, C.; Yeo, I. A.

2018-02-01

Although many of the regions on and close to the mid-ocean ridges have been extensively mapped and sampled, the abyssal intraplate regions remain essentially unsampled and unmapped, leaving huge gaps in our understanding of their geologic history and present activity. Prominent bathymetric features in these intraplate regions are fracture zones. Here we present bathymetric and sampling information from a transatlantic transect along the Vema Fracture Zone (ca. 11°N), covering crustal ages from 109 - 0 Ma on the African plate and 0-62 Ma on the South American plate. The Vema Fracture Zone is the intraplate trace of the active Vema Transform plate boundary, which offsets the present-day Mid-Atlantic Ridge by ca. 300 km left-laterally, juxtaposing zero-age crust with crust of 20 million years age. Our results show clear evidence of tectonic activity along most of the Fracture Zone, in most places likely associated with active fluid flow. Within the active Vema Transform at crustal ages of ca. 10 Ma we found clear indications of fluid flow both in the sediments and the overlying water column. This region is > 120 km from the nearest spreading axis and increases by almost an order of magnitude the maximum off-axis distance that active hydrothermal discharge has been found on the oceanic crust. Sampling of the igneous seafloor was possible at all crustal ages and the accretionary fabric imprinted on the plate during its production was prominent everywhere. Seafloor sediments show signs of extensive bioturbation. In one area, high concentrations of spherical Mn-nodules were also found and sampled. At the end of the transect we also mapped and sampled the Puerto Rico Trough, a > 8000 m-deep basin north of the Caribbean arc. Here the seafloor morphology is more complicated and strongly influenced by transpressive tectonics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, C.D.; Allison, M.L.

The Bluebell field is productive from the Tertiary lower Green River and Wasatch Formations of the Uinta Basin, Utah. The productive interval consists of thousands of feet of interbedded fractured clastic and carbonate beds deposited in a fluvial-dominated lacustrine environment. Wells in the Bluebell field are typically completed by perforating 40 or more beds over 1,000 to 3,000 vertical feet (300-900 m), then stimulating the entire interval. This completion technique is believed to leave many potentially productive beds damaged and/or untreated, while allowing water-bearing and low-pressure (thief) zones to communicate with the wellbore. Geologic and engineering characterization has been usedmore » to define improved completion techniques. A two-year characterization study involved detailed examination of outcrop, core, well logs, surface and subsurface fractures, produced oil-field waters, engineering parameters of the two demonstration wells, and analysis of past completion techniques and effectiveness. The characterization study resulted in recommendations for improved completion techniques and a field-demonstration program to test those techniques. The results of the characterization study and the proposed demonstration program are discussed in the second annual technical progress report. The operator of the wells was unable to begin the field demonstration this project year (October 1, 1995 to September 20, 1996). Correlation and thickness mapping of individual beds in the Wasatch Formation was completed and resulted in a. series of maps of each of the individual beds. These data were used in constructing the reservoir models. Non-fractured and fractured geostatistical models and reservoir simulations were generated for a 20-square-mile (51.8-km{sup 2}) portion of the Bluebell field. The modeling provides insights into the effects of fracture porosity and permeability in the Green River and Wasatch reservoirs.« less

Electron emission and acoustic emission from the fracture of graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Dickinson, J. T.; Jahan-Latibari, A.; Jensen, L. C.

1985-01-01

In past studies it has been shown that the fracture of materials leads to the emission of a variety of species, including electrons, ions, neutral molecules, and photons, all encompassed by the term 'fractoemission' (FE). In this paper, electron emission (EE) from the fracture of single graphite fibers and neat epoxy resin is examined. Measurements of EE are also combined with the detection of acoustic emission (AE) during the testing of graphite-epoxy composite specimens with various fiber orientation. The characteristics of these signals are related to known failure mechanisms in fiber-reinforced plastics. This study suggests that by comparing data from AE and FE measurements, one can detect and distinguish the onset of internal and external failure in composites. EE measurements are also shown to be sensitive to the locus of fracture in a composite material.

Rock fracture skeleton tracing by image processing and quantitative analysis by geometry features

NASA Astrophysics Data System (ADS)

Liang, Yanjie

2016-06-01

In rock engineering, fracture measurement is important for many applications. This paper proposes a novel method for rock fracture skeleton tracing and analyzing. As for skeleton localizing, the curvilinear fractures are multiscale enhanced based on a Hessian matrix, after image binarization, and clutters are post-processed by image analysis; subsequently, the fracture skeleton is extracted via ridge detection combined with a distance transform and thinning algorithm, after which gap sewing and burrs removal repair the skeleton. In regard to skeleton analyzing, the roughness and distribution of a fracture network are respectively described by the fractal dimensions D s and D b; the intersection and fragmentation of a fracture network are respectively characterized by the average number of ends and junctions per fracture N average and the average length per fracture L average. Three rock fracture surfaces are analyzed for experiments and the results verify that both the fracture tracing accuracy and the analysis feasibility are satisfactory using the new method.

New sidescan sonar and gravity evidence that the Nova-Canton Trough is a fracture zone

NASA Astrophysics Data System (ADS)

Joseph, Devorah; Taylor, Brian; Shor, Alexander N.

1992-05-01

A 1990 sidescan sonar survey in the eastern region of the Nova-Canton Trough mapped 138°-striking abyssal-hill fabric trending into 70°-striking trough structures. The location and angle of intersection of the abyssal hills with the eastern Nova-Canton Trough effectively disprove a spreading-center origin of this feature. Free-air gravity anomalies derived from satellite altimetry data show continuity, across the Line Islands, of the Nova-Canton Trough with the Clipperton Fracture Zone. The Canton-Clipperton trend is copolar, about a pole at 30°S, 152°W, with other coeval Pacific-Farallon fracture-zone segments, from the Pau to Marquesas fracture zones. This copolarity leads us to postulate a Pacific-Farallon spreading pattern for the magnetic quiet zone region north and east of the Manihiki Plateau, with the Nova-Canton Trough originating as a transform fault in this system.

Spatial and layer-controlled variability in fracture networks

NASA Astrophysics Data System (ADS)

Procter, Andrew; Sanderson, David J.

2018-03-01

Topological sampling, based on 1) node counting and 2) circular sampling areas, is used to measure fracture intensity in surface exposures of a layered limestone/shale sequence in north Somerset, UK. This method provides similar levels of precision as more traditional line samples, but is about 10 times quicker and allows characterization of the network topology. Georeferencing of photographs of the sample sites allows later analysis of trace lengths and orientations, and identification of joint set development. ANOVA tests support a complex interaction of within-layer, between-layer and between-location variability in fracture intensity, with the different layers showing anomalous intensity at different locations. This variation is not simply due to bed thickness, nor can it be related to any obvious compositional or textural variation between the limestone beds. These results are used to assess approaches to the spatial mapping of fracture intensity.

Description and analysis of cored hydraulic fractures -- Lost Hills field, Kern County, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fast, R.E.; Murer, A.S.; Timmer, R.S.

1994-05-01

An inclined observation well was drilled in shallow (2,000 ft) Opal-A diatomite. Seven sand-propped hydraulic fractures were cored and recovered. The hydraulic fractures were found within 5[degree] of the azimuth measured with tilt meters and were tilted 15[degree] from vertical, oriented perpendicular to the formation bedding dip. Hydraulic fractures widths ranged from less than one sand grain (40/60 mesh) to 0.4 in. Scanning electron microscopy (SEM) examination of fracture faces showed no damage to the matrix from proppant embedment or compaction, and no evidence of guard residue was detected in the proppant pack or on the formation face. Fractures appearmore » to be considerably longer than modeled. Three closely spaced fractures are interpreted to be branches of a single hydraulic fracture treatment. This paper presents a description of the fractures recovered during coring in Well OO2. Findings related to fracture dimensions and orientations, fracture sources, fracture permeability measurements, and fracture characteristics (proppant embedment, presence of gel residue) are presented. Implications related to field development are discussed.« less

Approaching a universal scaling relationship between fracture stiffness and fluid flow

NASA Astrophysics Data System (ADS)

Pyrak-Nolte, Laura J.; Nolte, David D.

2016-02-01

A goal of subsurface geophysical monitoring is the detection and characterization of fracture alterations that affect the hydraulic integrity of a site. Achievement of this goal requires a link between the mechanical and hydraulic properties of a fracture. Here we present a scaling relationship between fluid flow and fracture-specific stiffness that approaches universality. Fracture-specific stiffness is a mechanical property dependent on fracture geometry that can be monitored remotely using seismic techniques. A Monte Carlo numerical approach demonstrates that a scaling relationship exists between flow and stiffness for fractures with strongly correlated aperture distributions, and continues to hold for fractures deformed by applied stress and by chemical erosion as well. This new scaling relationship provides a foundation for simulating changes in fracture behaviour as a function of stress or depth in the Earth and will aid risk assessment of the hydraulic integrity of subsurface sites.

Integration of seismic interpretation and well logging analysis of Abu Roash D Member, Gindi Basin, Egypt: Implication for detecting and evaluating fractured carbonate reservoirs

NASA Astrophysics Data System (ADS)

Sarhan, Mohammad Abdelfattah; Basal, A. M. K.; Ibrahim, Ibrahim Mohamed

2017-11-01

Based on seismic interpretation, the time structure map on top of the Abu Roash D Member in the area of study within the Gindi Basin displays an NE-SW anticline plunging toward the NE intersected by two NE-SW reverse faults. This faulted anticline has been interpreted to have formed by the Late Cretaceous tectonic inversion resulting from the NW movement of the African Plate relative to Laurasia. This anticline creates a distinctive closure which may represent a possible structural hydrocarbon trap in the fractured limestone of the Abu Roash D Member in this area. Through well-logging analysis, the variable cementation exponent ;m; has been calculated using the Pickett Plot for the available wells in order to examine the presence of fractures within the entire carbonate Abu Roash D Member. The calculated ;m; for Abu Roash D in the two studied wells are 1.56 and 1.34 for SWQ-21 and SWQ-25; respectively which is indicative of the fractured limestone nature. The application of the correct ;m; (1.56) instead of 2 (traditional for the intergranular carbonate) for SWQ-21 well has revealed that, the water saturation for the uppermost part of Abu Roash D Member is lower than 50% (normal cut off for carbonate) possessing high porosity and reflecting good reservoir quality. The cross-plot between Archie water saturation (Sw) and neutron porosity (ΦN) for the uppermost part of this Member follows hyperbola with low BVW (Φ*Sw) value (0.06) which means that the reservoir is at irreducible state. The visual inspection for the log curve shapes in addition to the application of the presented technique in SWQ-25 well shows that the entire carbonate of Abu Roash D Member is water producing (Sw>50%). These results indicate that the upperpost part of the Abu Roash D Member in well SWQ-21 is fractured limestone and highly promising for hydrocarbon exploration within the Gindi Basin.

High resolution digital elevation modelling from TLS and UAV campaign reveals structural complexity at the 2014/15 Holuhraun eruption site, Iceland

NASA Astrophysics Data System (ADS)

Müller, Daniel; Walter, Thomas R.; Schöpa, Anne; Witt, Tanja; Steinke, Bastian; Gudmundsson, Magnús T.; Dürig, Tobias

2017-07-01

Fissure eruptions are commonly linked to magma dikes at depth, associated with elastic and anelastic surface deformation. Elastic deformation is well described by subsidence above, uplift and lateral widening perpendicular to the dike plane. The anelastic part is associated with the formation of a graben, bordered by graben parallel faults that might express as sets of fractures at the surface. Additionally secondary structures, like push ups, bends and step overs yield information about the deforming domain. The formation of such structures associated with fissure eruptions, however, is barely preserved in nature because of the rapid erosion or sediment coverage. Therefore, simple normal fault displacements are commonly assumed at dikes. At the 2014/2015 Holuhraun eruption sites (Iceland), evidence is increasing that the developing fractures are showing variations in their displacement modes. In an attempt to investigate these variations, a fieldwork mapping project combining Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle (UAV) based aerophoto analysis was realized. From this data, we generated locally high resolution Digital Elevation Models (DEMs) and a structural map that allows for identification of kinematic indicators and assessing particularities of the observed structures. We identified 315 fracture segments from satellite data. For single segments we measured strike directions including the amount of opening and opening angles, indicating that many of the measured fractures show transtensional dislocations. Out of these, 81 % are showing significant left-lateral slip, only 17% right-lateral slip and 2% pure tensile opening. We show that local complexities in the fracture traces and geometries are closely related to variations in the transtensional opening direction. Moreover, we identified local changes in fracture azimuths and offsets close to eruption sites, which we speculate to be associated with geometrical changes in the magma feeder itself. Results highlight that opening of fractures associated with an erupting fissure commonly show transtensional modes having both, left-lateral and right-lateral slip, with important implications for interpreting the expression of surface structures at rift zones elsewhere. Results further highlight the great value of UAV based high resolution data to contribute to the integrity of observations of structural complexities at local geologic events.

Facilitating the exploitation of ERTS imagery using snow enhancement techniques. [geological mapping of New England test area

NASA Technical Reports Server (NTRS)

Wobber, F. J.; Martin, K. R. (Principal Investigator); Amato, R. V.; Leshendok, T.

1974-01-01

The author has identified the following significant results. The procedure for conducting a regional geological mapping program utilizing snow-enhanced ERTS-1 imagery has been summarized. While it is recognized that mapping procedures in geological programs will vary from area to area and from geologist to geologist, it is believed that the procedure tested in this project is applicable over a wide range of mapping programs. The procedure is designed to maximize the utility and value of ERTS-1 imagery and aerial photography within the initial phase of geological mapping programs. Sample products which represent interim steps in the mapping formula (e.g. the ERTS Fracture-Lineament Map) have been prepared. A full account of these procedures and products will be included within the Snow Enhancement Users Manual.

Marine Geophysical Characterization of the Chain Fracture Zone in the Equatorial Atlantic

NASA Astrophysics Data System (ADS)

Harmon, N.; Rychert, C.; Agius, M. R.; Tharimena, S.; Kendall, J. M.

2017-12-01

The Chain Fracture zone is part of a larger system of fracture zones along the Mid Atlantic Ridge that is thought to be one of the original zones of weakness during the break up of Pangea. It is over 300 km long and produces earthquakes as large as Mw 6.9 on segments of the active fault zone. Here we present the results of two marine geophysical mapping campaigns over the active part of the Chain Fracture zone as part of the PI-LAB (Passive Imaging of the Lithosphere-Asthenosphere Boundary) experiment. We collected swath bathymetry, backscatter imagery, gravity and total field magnetic anomaly. We mapped the fault scarps within the transform fault system using the 50 m resolution swath and backscatter imagery. In addition, a 30-40 mGal residual Mantle Bouguer Anomaly determined from gravity analysis suggests the crust is by up to 1.4-2.0 km beneath the Chain relative to the adjacent ridge segments. However, in the eastern 75 km of the active transform we find evidence for thicker crust. The active fault system cuts through the region of thicker crust and there is a cluster of MW > 6 earthquakes in this region. There is a cluster of similar sized earthquakes on the western end where thinner crust is inferred. This suggests that variations in melt production and crustal thickness at the mid ocean ridge systems may have only a minor effect on the seismicity and longevity of the transform fault system.

Stress Rupture Fracture Model and Microstructure Evolution for Waspaloy

NASA Astrophysics Data System (ADS)

Yao, Zhihao; Zhang, Maicang; Dong, Jianxin

2013-07-01

Stress rupture behavior and microstructure evolution of nickel-based superalloy Waspaloy specimens from tenon teeth of an as-received 60,000-hour service-exposed gas turbine disk were studied between 923 K and 1088 K (650 °C and 815 °C) under initial applied stresses varying from 150 to 840 MPa. Good microstructure stability and performance were verified for this turbine disk prior to stress rupture testing. Microstructure instability, such as the coarsening and dissolution of γ' precipitates at the varying test conditions, was observed to be increased with temperature and reduced stress. Little microstructure variation was observed at 923 K (650 °C). Only secondary γ' instability occurred at 973 K (700 °C). Four fracture mechanisms were obtained. Transgranular creep fracture was exhibited up to 923 K (650 °C) and at high stress. A mixed mode of transgranular and intergranular creep fracture occurred with reduced stress as a transition to intergranular creep fracture (ICF) at low stress. ICF was dominated by grain boundary sliding at low temperature and by the nucleation and growth of grain boundary cavities due to microstructure instability at high temperature. The fracture mechanism map and microstructure-related fracture model were constructed. Residual lifetime was also evaluated by the Larson-Miller parameter method.

Sedimentation in the Kane fracture zone, western North Atlantic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaroslow, G.E.

1991-03-01

The Kane fracture zone, a deep narrow trough in oceanic crust, has provided an ideal depocenter for reservation on the seismic stratigraphic record of the North Atlantic basin. The acoustic stratigraphy in single-channel and multichannel seismic reflection profiles crossing the Kane fracture zone in the western North Atlantic has been examined in order to scrutinize age processes within a fracture zone. Maps of total sediment thickness have provided insight into overall sediment distribution and the influence of topography on sedimentation. Eight reflectors have been traced and correlated with lithostratigraphy at Deep Sea Drilling Project (DSDP) sites. The Bermuda Rise, amore » prominent topographic feature, has had a profound effect on the distribution of sediments within the fracture zone. Since late Eocene, the rise has blocked transport by turbidity currents of terrigenous sediments to distal portions of the fracture valley. A 1,000-m-thick turbidite pond within the fracture zone east of the Bermuda Rise has been determined to have been derived from local sources. Within the ponded sequence a seismic discontinuity is estimated to be early Oligocene and postdates the emergence of the Bermuda Rise, adding an independent age constraint on the development of the rise. The pond terminates against a structural dam at 55{degree}20W, east of which the fracture zone is essentially sediment starved.« less

The Geothermic Fatigue Hydraulic Fracturing Experiment in Äspö Hard Rock Laboratory, Sweden: New Insights Into Fracture Process through In-situ AE Monitoring

NASA Astrophysics Data System (ADS)

Kwiatek, G.; Plenkers, K.; Zang, A.; Stephansson, O.; Stenberg, L.

2016-12-01

The geothermic Fatigue Hydraulic Fracturing (FHF) in situ experiment (Nova project 54-14-1) took place in the Äspö Hard Rock Laboratory/Sweden in a 1.8 Ma old granitic to dioritic rock mass. The experiment aims at optimizing geothermal heat exchange in crystalline rock mass by multistage hydraulic fracturing at 10 m scale. Six fractures are driven by three different water injection schemes (continuous, cyclic, pulse pressurization) inside a 28 m long, horizontal borehole at depth level 410 m. The rock volume subject to hydraulic fracturing and monitored by three different networks with acoustic emission (AE), micro-seismicity and electromagnetic sensors is about 30 m x 30 m x 30 m in size. The 16-channel In-situ AE monitoring network by GMuG monitored the rupture generation and propagation in the frequency range 1000 Hz to 100,000 Hz corresponding to rupture dimensions from cm- to dm-scale. The in-situ AE monitoring system detected and analyzed AE activity in-situ (P- and S-wave picking, localization). The results were used to review the ongoing microfracturing activity in near real-time. The in-situ AE monitoring network successfully recorded and localized 196 seismic events for most, but not all, hydraulic fractures. All AE events detected in-situ occurred during fracturing time periods. The source parameters (fracture sizes, moment magnitudes, static stress drop) of AE events framing injection periods were calculated using the combined spectral fitting/spectra ratio techniques. The AE activity is clustered in space and clearly outline the fractures location, its orientation, and expansion as well as their temporal evolution. The outward migration of AE events away from the borehole is observed. Fractures extend up to 7 m from the injection interval in the horizontal borehole. The fractures orientation and location correlate for most fractures roughly with the results gained by image packer. Clear differences in seismic response between hydraulic fractures in different formations and injection schemes are visible which need further investigation. For further analysis all AE data of fracturing time periods were recorded continuously with 1 MHz sampling frequency per channel.

Assessing groundwater accessibility in the Kharga Basin, Egypt: A remote sensing approach

NASA Astrophysics Data System (ADS)

Parks, Shawna; Byrnes, Jeffrey; Abdelsalam, Mohamed G.; Laó Dávila, Daniel A.; Atekwana, Estella A.; Atya, Magdy A.

2017-12-01

We used multi-map analysis of remote sensing and ancillary data to identify potentially accessible sites for groundwater resources in the Kharga Basin in the Western Desert of Egypt. This basin is dominated by Cretaceous sandstone formations and extends within the Nubian Sandstone Aquifer. It is dissected by N-S and E-W trending faults, possibly acting as conduits for upward migration of groundwater. Analysis of paleo-drainage using Digital Elevation Model (DEM) generated from the Shuttle Radar Topography Mission (SRTM) data shows that the Kharga was a closed basin that might have been the site of a paleo-lake. Lake water recharged the Nubian Sandstone Aquifer during the wetter Holocene time. We generated the following layers for the multi-map analysis: (1) Fracture density map from the interpretation of Landsat Operational Land Imager (OLI), SRTM DEM, and RADARSAT data. (2) Thermal Inertia (TI) map (for moisture content imaging) from the Moderate Resolution Imaging Spectroradiometer (MODIS) data. (3) Hydraulic conductivity map from mapping lithological units using the Landsat OLI and previously published data. (4) Aquifer thickness map from previously published data. We quantitatively ranked the Kharga Basin by considering that regions of high fracture density, high TI, thicker aquifer, and high hydraulic conductivity have higher potential for groundwater accessibility. Our analysis shows that part of the southern Kharga Basin is suitable for groundwater extraction. This region is where N-S and E-W trending faults intersect, has relatively high TI and it is underlain by thick aquifer. However, the suitability of this region for groundwater use will be reduced significantly when considering the changes in land suitability and economic depth to groundwater extraction in the next 50 years.

Use of the Fracture Continuum Model for Numerical Modeling of Flow and Transport of Deep Geologic Disposal of Nuclear Waste in Crystalline Rock

NASA Astrophysics Data System (ADS)

Hadgu, T.; Kalinina, E.; Klise, K. A.; Wang, Y.

2015-12-01

Numerical modeling of disposal of nuclear waste in a deep geologic repository in fractured crystalline rock requires robust characterization of fractures. Various methods for fracture representation in granitic rocks exist. In this study we used the fracture continuum model (FCM) to characterize fractured rock for use in the simulation of flow and transport in the far field of a generic nuclear waste repository located at 500 m depth. The FCM approach is a stochastic method that maps the permeability of discrete fractures onto a regular grid. The method generates permeability fields using field observations of fracture sets. The original method described in McKenna and Reeves (2005) was designed for vertical fractures. The method has since then been extended to incorporate fully three-dimensional representations of anisotropic permeability, multiple independent fracture sets, and arbitrary fracture dips and orientations, and spatial correlation (Kalinina et al. 20012, 2014). For this study the numerical code PFLOTRAN (Lichtner et al., 2015) has been used to model flow and transport. PFLOTRAN solves a system of generally nonlinear partial differential equations describing multiphase, multicomponent and multiscale reactive flow and transport in porous materials. The code is designed to run on massively parallel computing architectures as well as workstations and laptops (e.g. Hammond et al., 2011). Benchmark tests were conducted to simulate flow and transport in a specified model domain. Distributions of fracture parameters were used to generate a selected number of realizations. For each realization, the FCM method was used to generate a permeability field of the fractured rock. The PFLOTRAN code was then used to simulate flow and transport in the domain. Simulation results and analysis are presented. The results indicate that the FCM approach is a viable method to model fractured crystalline rocks. The FCM is a computationally efficient way to generate realistic representation of complex fracture systems. This approach is of interest for nuclear waste disposal models applied over large domains.

D-dimer as an applicable test for detection of posttraumatic deep vein thrombosis in lower limb fracture.

PubMed

Bakhshi, Hooman; Alavi-Moghaddam, Mostafa; Wu, Karin C; Imami, Mohammad; Banasiri, Mohammad

2012-06-01

Measuring the plasma levels of D-dimer is an accurate and easy modality to detect deep vein thrombosis (DVT) in nontraumatic settings. However, the diagnostic reliability of D-dimer assays in detecting posttraumatic DVT among patients with lower limb fracture undergoing orthopedic surgery is not validated. In this study, 141 patients with lower limb fracture admitted through the emergency department and undergoing orthopedic surgery were enrolled. Postoperative venous blood samples for D-dimer assay were taken on the 1st, 7th, and 28th postoperative days. Color Doppler sonography examination of both lower limbs was performed at the same time as a standard test. Eight out of the 141 patients (6%) had acute DVT based on Color Doppler sonography. Mean D-dimer was 2160 ng/mL in DVT positive patients and 864 in DVT negative patients. D-dimer levels greater than 1000 ng/mL were 100% sensitive and 71% specific for detecting postoperative DVT. D-dimer assay is a useful and sensitive test for detecting posttraumatic DVT.

Optimizing the design of vertical seismic profiling (VSP) for imaging fracture zones over hardrock basement geothermal environments

NASA Astrophysics Data System (ADS)

Reiser, Fabienne; Schmelzbach, Cedric; Maurer, Hansruedi; Greenhalgh, Stewart; Hellwig, Olaf

2017-04-01

A primary focus of geothermal seismic imaging is to map dipping faults and fracture zones that control rock permeability and fluid flow. Vertical seismic profiling (VSP) is therefore a most valuable means to image the immediate surroundings of an existing borehole to guide, for example, the placing of new boreholes to optimize production from known faults and fractures. We simulated 2D and 3D acoustic synthetic seismic data and processed it through to pre-stack depth migration to optimize VSP survey layouts for mapping moderately to steeply dipping fracture zones within possible basement geothermal reservoirs. Our VSP survey optimization procedure for sequentially selecting source locations to define the area where source points are best located for optimal imaging makes use of a cross-correlation statistic, by which a subset of migrated shot gathers is compared with a target or reference image from a comprehensive set of source gathers. In geothermal exploration at established sites, it is reasonable to assume that sufficient à priori information is available to construct such a target image. We generally obtained good results with a relatively small number of optimally chosen source positions distributed over an ideal source location area for different fracture zone scenarios (different dips, azimuths, and distances from the surveying borehole). Adding further sources outside the optimal source area did not necessarily improve the results, but rather resulted in image distortions. It was found that fracture zones located at borehole-receiver depths and laterally offset from the borehole by 300 m can be imaged reliably for a range of the different dips, but more source positions and large offsets between sources and the borehole are required for imaging steeply dipping interfaces. When such features cross-cut the borehole, they are particularly difficult to image. For fracture zones with different azimuths, 3D effects are observed. Far offset source positions contribute less to the image quality as fracture zone azimuth increases. Our optimization methodology is best suited for designing future field surveys with a favorable benefit-cost ratio in areas with significant à priori knowledge. Moreover, our optimization workflow is valuable for selecting useful subsets of acquired data for optimum target-oriented processing.

The osteoporosis-pseudoglioma syndrome locus is on chromosome 11q

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Y.; Vikkula, M.; Boon, L.M.

The osteoporosis-pseudoglioma syndrome (OPS), is a rare autosomal recessive disorder characterized by severe osteoporosis with multiple fractures and blindness, both occurring in childhood. The precise pathogenic mechanism for OPS is unknown. Insights into its cause may be useful towards understanding the pathophysiology of more common disorders, such as senile osteoporosis, persistent hyperplasia of the primary vitreous, and retinopathy of prematurity, whose features have some similarity with OPS. As a first step in determining the cause of OPS, we have mapped the locus of the disorder to chromosome 11q. This was accomplished by assuming genetic homogeneity and by performing linkage analysismore » with homozygosity mapping in 18 individuals (7 patients, 5 unaffected siblings, and 7 parents) from 3 different consanguineous kindreds. Since the condition could be caused by an abnormal extracellular matrix component, we began by testing several candidate genes (e.g., COL1A1, COL1A2, Osteopontin, Osteonectin) distributed on 12 different chromosomes. We also initiated a systematic search at 20 cM intervals with highly polymorphic simple sequence tandem repeats. Linkage and homozygosity was detected with marker D11S913 (LOD score 3.8 at {theta} = 0). Additional markers are being tested to confirm this observation. The fibroblast collagenase, fibronectin-like-2 gene and rod outer segment protein-1 (ROM 1) also map to chromosome 11q and are candidate genes.« less

Correlative Light-Electron Fractography of Interlaminar Fracture in a Carbon-Epoxy Composite.

PubMed

Hein, Luis Rogerio de O; Campos, Kamila A de

2015-12-01

This work evaluates the use of light microscopes (LMs) as a tool for interlaminar fracture of polymer composite investigation with the aid of correlative fractography. Correlative fractography consists of an association of the extended depth of focus (EDF) method, based on reflected LM, with scanning electron microscopy (SEM) to evaluate interlaminar fractures. The use of these combined techniques is exemplified here for the mode I fracture of carbon-epoxy plain-weave reinforced composite. The EDF-LM is a digital image-processing method that consists of the extraction of in-focus pixels for each x-y coordinate in an image from a stack of Z-ordered digital pictures from an LM, resulting in a fully focused picture and a height elevation map for each stack. SEM is the most used tool for the identification of fracture mechanisms in a qualitative approach, with the combined advantages of a large focus depth and fine lateral resolution. However, LMs, with EDF software, may bypass the restriction on focus depth and present enough lateral resolution at low magnification. Finally, correlative fractography can provide the general comprehension of fracture processes, with the benefits of the association of different resolution scales and contrast modes.

Faults, Fractures, and Lineaments in the Mineral Mountains, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joe Moore

This submission includes a shapefile of the Opal Mound Fault, and multiple datasets of lineaments mapped in the Mineral Mountains which overlook the Utah FORGE site, hyperlinked to rose diagrams in a polygon grid shapefile.

Spatial analysis of geologic and hydrologic features relating to sinkhole occurrence in Jefferson County, West Virginia

USGS Publications Warehouse

Doctor, Daniel H.; Doctor, Katarina Z.

2012-01-01

In this study the influence of geologic features related to sinkhole susceptibility was analyzed and the results were mapped for the region of Jefferson County, West Virginia. A model of sinkhole density was constructed using Geographically Weighted Regression (GWR) that estimated the relations among discrete geologic or hydrologic features and sinkhole density at each sinkhole location. Nine conditioning factors on sinkhole occurrence were considered as independent variables: distance to faults, fold axes, fracture traces oriented along bedrock strike, fracture traces oriented across bedrock strike, ponds, streams, springs, quarries, and interpolated depth to groundwater. GWR model parameter estimates for each variable were evaluated for significance, and the results were mapped. The results provide visual insight into the influence of these variables on localized sinkhole density, and can be used to provide an objective means of weighting conditioning factors in models of sinkhole susceptibility or hazard risk.

Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

NASA Astrophysics Data System (ADS)

Schultz, Ryan; Stern, Virginia; Novakovic, Mark; Atkinson, Gail; Gu, Yu Jeffrey

2015-04-01

Within central Alberta, Canada, a new sequence of earthquakes has been recognized as of 1 December 2013 in a region of previous seismic quiescence near Crooked Lake, ~30 km west of the town of Fox Creek. We utilize a cross-correlation detection algorithm to detect more than 160 events to the end of 2014, which is temporally distinguished into five subsequences. This observation is corroborated by the uniqueness of waveforms clustered by subsequence. The Crooked Lake Sequences have come under scrutiny due to its strong temporal correlation (>99.99%) to the timing of hydraulic fracturing operations in the Duvernay Formation. We assert that individual subsequences are related to fracturing stimulation and, despite adverse initial station geometry, double-difference techniques allow us to spatially relate each cluster back to a unique horizontal well. Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first-order observations of hydraulic fracturing induced seismicity.

Electrically conductive proppant and methods for detecting, locating and characterizing the electrically conductive proppant

DOEpatents

Cannan, Chad; Bartel, Lewis; Palisch, Terrence; Aldridge, David

2015-01-13

Electrically conductive proppants and methods for detecting, locating, and characterizing same are provided. The electrically conductive proppant can include a substantially uniform coating of an electrically conductive material having a thickness of at least 500 nm. The method can include injecting a hydraulic fluid into a wellbore extending into a subterranean formation at a rate and pressure sufficient to open a fracture therein, injecting into the fracture a fluid containing the electrically conductive proppant, electrically energizing the earth at or near the fracture, and measuring three dimensional (x, y, and z) components of electric and magnetic field responses at a surface of the earth or in an adjacent wellbore.

Fracto-emission from single fibres of Kevlar

NASA Technical Reports Server (NTRS)

Dickinson, J. T.; Jahan-Latibari, A.; Jensen, L. C.

1985-01-01

Fracto-emission (FE) is the emission of particles (e.g. electrons, ions and photons) during and following fracture. In this paper, we present data on electron emission (EE) and positive ion emission (PIE) from the tensile fracture of Kevlar single fibers. The fibers were initially fractured in pure tension, where a stranded form of fracture was observed, often with multiple peaks spread over several hundred microseconds. The loading condition was then changed by stretching and breaking the fibers over a dull metal edge. With this change in the loading, different forms of fracture were observed, each with distinctive forms of emission curves. When fracture was accompanied by extensive fibril formation, total emission was high and both EE and PIE decay times were long relative to fractures in which little fibril formation occurred. The results of this study suggest that FE has some applicability as a tool for the detection of fracture mechanisms of single fibers.

Foot fractures frequently misdiagnosed as ankle sprains.

PubMed

Judd, Daniel B; Kim, David H

2002-09-01

Most ankle injuries are straightforward ligamentous injuries. However, the clinical presentation of subtle fractures can be similar to that of ankle sprains, and these fractures are frequently missed on initial examination. Fractures of the talar dome may be medial or lateral, and they are usually the result of inversion injuries, although medial injuries may be atraumatic. Lateral talar process fractures are characterized by point tenderness over the lateral process. Posterior talar process fractures are often associated with tenderness to deep palpation anterior to the Achilles tendon over the posterolateral talus, and plantar flexion may exacerbate the pain. These fractures can often be managed nonsurgically with nonweight-bearing status and a short leg cast worn for approximately four weeks. Delays in treatment can result in long-term disability and surgery. Computed tomographic scans or magnetic resonance imaging may be required because these fractures are difficult to detect on plain films.

Integrated workflow for characterizing and modeling fracture network in unconventional reservoirs using microseismic data

NASA Astrophysics Data System (ADS)

Ayatollahy Tafti, Tayeb

We develop a new method for integrating information and data from different sources. We also construct a comprehensive workflow for characterizing and modeling a fracture network in unconventional reservoirs, using microseismic data. The methodology is based on combination of several mathematical and artificial intelligent techniques, including geostatistics, fractal analysis, fuzzy logic, and neural networks. The study contributes to scholarly knowledge base on the characterization and modeling fractured reservoirs in several ways; including a versatile workflow with a novel objective functions. Some the characteristics of the methods are listed below: 1. The new method is an effective fracture characterization procedure estimates different fracture properties. Unlike the existing methods, the new approach is not dependent on the location of events. It is able to integrate all multi-scaled and diverse fracture information from different methodologies. 2. It offers an improved procedure to create compressional and shear velocity models as a preamble for delineating anomalies and map structures of interest and to correlate velocity anomalies with fracture swarms and other reservoir properties of interest. 3. It offers an effective way to obtain the fractal dimension of microseismic events and identify the pattern complexity, connectivity, and mechanism of the created fracture network. 4. It offers an innovative method for monitoring the fracture movement in different stages of stimulation that can be used to optimize the process. 5. Our newly developed MDFN approach allows to create a discrete fracture network model using only microseismic data with potential cost reduction. It also imposes fractal dimension as a constraint on other fracture modeling approaches, which increases the visual similarity between the modeled networks and the real network over the simulated volume.

Environmental controls on micro fracture processes in shelf ice

NASA Astrophysics Data System (ADS)

Sammonds, Peter

2013-04-01

The recent retreat and collapse of the ice shelves on the Antarctic Peninsula has been associated with regional atmospheric warming, oceanic warming, increased summer melt and shelf flexure. Although the cause of collapse is a matter of active discussion, the process is that of fracture of a creep-brittle material, close to its melting point. The environmental controls on how fracturing initiates, at a micro-scale, strongly determine the macroscopic disintegration of ice shelves. In particular the shelf temperature profile controls the plasticity of the ice shelf; the densification of shelf ice due to melting and re-freezing affects the crack tip stress intensity; the accretion of marine ice at the bottom of the shelf imposes a thermal/mechanical discontinuity; saline environments control crack tip stress corrosion; cyclic loading promotes sub-critical crack propagation. These strong environmental controls on shelf ice fracture means that assessing shelf stability is a non-deterministic problem. How these factors may be parameterized in ice shelf models, through the use of fracture mechanisms maps, is discussed. The findings are discussed in relation to the stability of Larsen C.

Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hibbs, Andrew; Wilt, Michael

This report describes the results of the first of its kind monitoring of a hydrofracture operation with electromagnetic measurements. The researchers teamed with oil and gas producer Encana Corporation to design and execute a borehole to surface monitoring of three fracture stages at a well pad in central Colorado. The field project consisted of an equipment upgrade, a survey design and modeling phase, several weeks of data collection, and data processing and interpretation. Existing Depth to Surface Resistivity (DSR) instrumentation was upgraded to allow for continuous high precision recording from downhole sources. The full system can now collect data continuouslymore » for up to 72 hours, which is sufficient to measure data for 10 frac stages. Next we used numerical modeling and frac treatment data supplied by Encana to design a field survey to detect EM signal from induced fractures. Prior to modeling we developed a novel technique for using well casing as an antenna for a downhole source. Modeling shows that 1) a measurable response for an induced fracture could be achieved if the facture fluid was of high salinity 2) an optimum fracture response is created when the primary source field is parallel to the well casing but perpendicular to the fracture direction. In mid-July, 2014 we installed an array of more than 100 surface sensors, distributed above the treatment wells and extending for approximately 1 km north and 750 m eastward. We applied a 0.6 Hz square wave signal to a downhole current electrode located in a horizontal well 200 m offset from the treatment well with a return electrode on the surface. The data were transmitted to a recording trailer via Wi-Fi where we monitored receiver and transmitter channels continuously in a 72-hour period which covered 7 frac stages, three of which were high salinity. Although the background conditions were very noisy we were able to extract a clear signal from the high salinity stages. Initial data interpretation attempts consisting of trying to directly invert collected data using a simple background starting model did not produce reasonable models. We next used a simulated data set to develop a constrained inversion workflow that places the downhole fracture in the correct location. Finally, we used a combination of forward and inverse models to fit the collected data to a model that incorporated 3 frac stages. This project provided a first-of-its-kind application of EM technology to map an induced fracture. The results demonstrated a clear anomaly during the operation that can be fit to a reasonable model of an induced fracture.« less

New bone post-processing tools in forensic imaging: a multi-reader feasibility study to evaluate detection time and diagnostic accuracy in rib fracture assessment.

PubMed

Glemser, Philip A; Pfleiderer, Michael; Heger, Anna; Tremper, Jan; Krauskopf, Astrid; Schlemmer, Heinz-Peter; Yen, Kathrin; Simons, David

2017-03-01

The aim of this multi-reader feasibility study was to evaluate new post-processing CT imaging tools in rib fracture assessment of forensic cases by analyzing detection time and diagnostic accuracy. Thirty autopsy cases (20 with and 10 without rib fractures in autopsy) were randomly selected and included in this study. All cases received a native whole body CT scan prior to the autopsy procedure, which included dissection and careful evaluation of each rib. In addition to standard transverse sections (modality A), CT images were subjected to a reconstruction algorithm to compute axial labelling of the ribs (modality B) as well as "unfolding" visualizations of the rib cage (modality C, "eagle tool"). Three radiologists with different clinical and forensic experience who were blinded to autopsy results evaluated all cases in a random manner of modality and case. Rib fracture assessment of each reader was evaluated compared to autopsy and a CT consensus read as radiologic reference. A detailed evaluation of relevant test parameters revealed a better accordance to the CT consensus read as to the autopsy. Modality C was the significantly quickest rib fracture detection modality despite slightly reduced statistic test parameters compared to modalities A and B. Modern CT post-processing software is able to shorten reading time and to increase sensitivity and specificity compared to standard autopsy alone. The eagle tool as an easy to use tool is suited for an initial rib fracture screening prior to autopsy and can therefore be beneficial for forensic pathologists.

The surface geometry of inherited joint and fracture trace patterns resulting from active and passive deformation

NASA Technical Reports Server (NTRS)

Podwysocki, M. H.; Gold, D. P.

1974-01-01

Hypothetical models are considered for detecting subsurface structure from the fracture or joint pattern, which may be influenced by the structure and propagated to the surface. Various patterns of an initially orthogonal fracture grid are modeled according to active and passive deformation mechanisms. In the active periclinal structure with a vertical axis, fracture frequency increased both over the dome and basin, and remained constant with decreasing depth to the structure. For passive periclinal features such as a reef or sand body, fracture frequency is determined by the arc of curvature and showed a reduction over the reefmound and increased over the basin.

Impact of Bruxism on Ceramic Defects in Implant-Borne Fixed Dental Prostheses: A Retrospective Study.

PubMed

Mikeli, Aikaterini; Walter, Michael H

2016-01-01

Ceramic veneer fracture is a frequent complication in implant-borne fixed restorations. The retrospective clinical study assesses the effect of bruxism on this complication. A sample of 507 implant-borne fixed units inserted between 1995 and 2011 in 144 patients were examined. Any detected veneer fractures were assigned to one of four groups according to extent and position. A hypothetical correlation between bruxism and ceramic veneer fractures was examined. Of 34 patients (23.6%) with at least one ceramic veneer fracture, 24 were bruxers (70%) and 10 were nonbruxers (30%) (P = .002). Bruxism may pose a risk for ceramic fractures.

Integrated geophysical study of the geothermal system in the southern part of Nisyros Island, Greece

NASA Astrophysics Data System (ADS)

Lagios, E.; Apostolopoulos, G.

1995-10-01

The study of the high-enthalpy geothermal field of Nisyros Island is of great importance, because of the planned construction of a geothermal power station. The purpose of the applied geophysical surveys — gravity, SP, VLF and audio-magnetotelluric — in southernmost Nisyros was to investigate the major and minor faulting zones which are geothermally active, i.e. whether geothermal fluid circulation occurs in these zones. The survey lines, four parallel traverses of about 1500 m length, were chosen to be almost transverse to the main faults of the area. The SP method was the main reconnaissance technique, with the VLF and gravity measurements correlating with the "SP model". Previously proposed SP data acquisition and reduction techniques were used, followed by a 2-D interpretation of the SP map which apparently locates the position of the fracture zones (geothermally active). The SP and VLF anomalies are believed to be generated by the same source (subsurface flow of fluid, heat and ions). Hence, at the place of a vertical geothermal fluid circulation zone, the curve of SP dipole-like anomaly changes its behaviour and the curve of the VLF anomaly takes maximum values for the in-phase component and minimum values for the out-of-phase component. On the VLF map of the survey area, the zones detected with the SP interpretation coincide with the maximum values of the VLF in-phase component. The geothermal fluid circulation zones, detected by the SP method, appear to be well correlated with corresponding features derived from the gravity and the AMT surveys. In particular, the AMT soundings indicate two zones of geothermal fluid circulation instead of the one the SP method detected in the central part of the investigated area.

Performance of an artificial neural network for vertical root fracture detection: an ex vivo study.

PubMed

Kositbowornchai, Suwadee; Plermkamon, Supattra; Tangkosol, Tawan

2013-04-01

To develop an artificial neural network for vertical root fracture detection. A probabilistic neural network design was used to clarify whether a tooth root was sound or had a vertical root fracture. Two hundred images (50 sound and 150 vertical root fractures) derived from digital radiography--used to train and test the artificial neural network--were divided into three groups according to the number of training and test data sets: 80/120,105/95 and 130/70, respectively. Either training or tested data were evaluated using grey-scale data per line passing through the root. These data were normalized to reduce the grey-scale variance and fed as input data of the neural network. The variance of function in recognition data was calculated between 0 and 1 to select the best performance of neural network. The performance of the neural network was evaluated using a diagnostic test. After testing data under several variances of function, we found the highest sensitivity (98%), specificity (90.5%) and accuracy (95.7%) occurred in Group three, for which the variance of function in recognition data was between 0.025 and 0.005. The neural network designed in this study has sufficient sensitivity, specificity and accuracy to be a model for vertical root fracture detection. © 2012 John Wiley & Sons A/S.

Induction logging device

DOEpatents

Koelle, A.R.; Landt, J.A.

An instrument is disclosed for mapping vertical conductive fractures in a resistive bedrock, magnetically inducing eddy currents by a pair of vertically oriented, mutually perpendicular, coplanar coils. The eddy currents drive magnetic fields which are picked up by a second, similar pair of coils.

Anomalous Transport in Natural Fracture Networks Induced by Tectonic Stress

NASA Astrophysics Data System (ADS)

Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.

2017-12-01

Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the high uncertainty and large heterogeneity associated with fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transportthrough fractured rock remains poorly understood. The link between anomalous (non-Fickian) transport and confining stress has been shown, only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of geologic (tectonic) stress on flow and tracer transport through natural fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM) [2], which can capture the deformation of matrix blocks, reactivation of pre-existing fractures, and propagation of new cracks, upon changes in the stress field. We apply the model to a fracture network extracted from the geological map of an actual rock outcrop to obtain the aperture field at different stress conditions. We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture network, and show that the stress state is a powerful determinant of transport behavior: (1) An anisotropic stress state induces preferential flow paths through shear dilation; (2) An increase in geologic stress increases aperture heterogeneity that induces late-time tailing of particle breakthrough curves. Finally, we develop an effective transport model that captures the anomalous transport through the stressed fracture network. Our results point to a heretofore unrecognized link between geomechanics and anomalous transport in natural fractured media. [1] P. K. Kang, S. Brown, and R. Juanes, Earth and Planetary Science Letters, 454, 46-54 (2016). [2] Q. Lei, J. P. Latham, and C. F. Tsang, Computers and Geotechnics, 85, 151-176 (2017).

Radiographic and ultrasonic characterization of sintered silicon carbide

NASA Technical Reports Server (NTRS)

Baaklini, G. Y.; Abel, P. B.

1988-01-01

The capabilities were investigated of projection microfocus X-radiography, ultrasonic velocity and attenuation, and reflection scanning acoustic microscopy for characterizing silicon carbide specimens. Silicon carbide batches covered a range of densities and different microstructural characteristics. Room temperature, four point flexural strength tests were conducted. Fractography was used to identify types, sizes, and locations of fracture origins. Fracture toughness values were calculated from fracture strength and flaw characterization data. Detection capabilities of radiography and acoustic microscopy for fracture-causing flaws were evaluated. Applicability of ultrasonics for verifying material strength and toughness was examined.

Flaw imaging and ultrasonic techniques for characterizing sintered silicon carbide

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Abel, Phillip B.

1987-01-01

The capabilities were investigated of projection microfocus x-radiography, ultrasonic velocity and attenuation, and reflection scanning acoustic microscopy for characterizing silicon carbide specimens. Silicon carbide batches covered a range of densities and different microstructural characteristics. Room temperature, four point flexural strength tests were conducted. Fractography was used to identify types, sizes, and locations of fracture origins. Fracture toughness values were calculated from fracture strength and flaw characterization data. Detection capabilities of radiography and acoustic microscopy for fracture-causing flaws were evaluated. Applicability of ultrasonics for verifying material strength and toughness was examined.

Whole-body low-dose computed tomography in multiple myeloma staging: Superior diagnostic performance in the detection of bone lesions, vertebral compression fractures, rib fractures and extraskeletal findings compared to radiography with similar radiation exposure.

PubMed

Lambert, Lukas; Ourednicek, Petr; Meckova, Zuzana; Gavelli, Giampaolo; Straub, Jan; Spicka, Ivan

2017-04-01

The primary objective of the present prospective study was to compare the diagnostic performance of conventional radiography (CR) and whole-body low-dose computed tomography (WBLDCT) with a comparable radiation dose reconstructed using hybrid iterative reconstruction technique, in terms of the detection of bone lesions, skeletal fractures, vertebral compressions and extraskeletal findings. The secondary objective was to evaluate lesion attenuation in relation to its size. A total of 74 patients underwent same-day skeletal survey by CR and WBLDCT. In CR and WBLDCT, two readers assessed the number of osteolytic lesions at each region and stage according to the International Myeloma Working Group (IMWG) criteria. A single reader additionally assessed extraskeletal findings and their significance, the number of vertebral compressions and bone fractures. The radiation exposure was 2.7±0.9 mSv for WBLDCT and 2.5±0.9 mSv for CR (P=0.054). CR detected bone involvement in 127 out of 486 regions (26%; P<0.0001), confirmed by WBLDCT. CR underestimated the disease stage in 16% and overestimated it in 8% of the patients (P=0.0077). WBLDCT detected more rib fractures compared with CR (188 vs. 47; P<0.0001), vertebral compressions (93 vs. 67; P=0.010) and extraskeletal findings (194 vs. 52; P<0.0001). There was no correlation observed between lesion size (≥5 mm) and its attenuation (r=-0.006; P=0.93). The inter-observer agreement for the presence of osteolytic lesions was κ=0.76 for WBLDCT, and κ=0.55 for CR. The present study concluded that WBLDCT with hybrid iterative reconstruction technique demonstrates superiority to CR with an identical radiation dose in the detection of bone lesions, skeletal fractures, vertebral compressions and extraskeletal findings, which results in up- or downstaging in 24% patients according to the IMWG criteria. The attenuation of osteolytic lesions can be measured with the avoidance of the partial volume effect.

Fracture of fiber-reinforced composites analyzed via acoustic emission.

PubMed

Ereifej, Nadia S; Oweis, Yara G; Altarawneh, Sandra K

2015-01-01

This study investigated the fracture resistance of composite resins using a three-point bending test and acoustic emission (AE) analysis. Three groups of specimens (n=15) were prepared: non-reinforced BelleGlass HP composite (NRC), unidirectional (UFRC) and multidirectional (MFRC) fiber-reinforced groups which respectively incorporated unidirectional Stick and multidirectional StickNet fibers. Specimens were loaded to failure in a universal testing machine while an AE system was used to detect audible signals. Initial fracture strengths and AE amplitudes were significantly lower than those at final fracture in all groups (p<0.05). Initial fracture strength of UFRC (170.0 MPa) was significantly higher than MFRC (124.6 MPa) and NRC (87.9 MPa). Final fracture strength of UFRC (198.1 MPa) was also significantly higher than MFRC (151.0 MPa) and NRC (109.2 MPa). Initial and final fracture strengths were significantly correlated (r=0.971). It was concluded that fiber reinforcement improved the fracture resistance of composite resin materials and the monitoring of acoustic signals revealed significant information regarding the fracture process.

The Practical Application of Aqueous Geochemistry in Mapping Groundwater Flow Systems in Fractured Rock Masses

NASA Astrophysics Data System (ADS)

Bursey, G.; Seok, E.; Gale, J. E.

2017-12-01

Flow to underground mines and open pits takes place through an interconnected network of regular joints/fractures and intermediate to large scale structural features such as faults and fracture zones. Large scale features can serve either as high permeability pathways or as barriers to flow, depending on the internal characteristics of the structure. Predicting long term water quality in barrier-well systems and long-term mine water inflows over a mine life, as a mine expands, requires the use of a 3D numerical flow and transport code. The code is used to integrate the physical geometry of the fractured-rock mass with porosity, permeability, hydraulic heads, storativity and recharge data and construct a model of the flow system. Once that model has been calibrated using hydraulic head and permeability/inflow data, aqueous geochemical and isotopic data provide useful tools for validating flow-system properties, when one is able to recognize and account for the non-ideal or imperfect aspects of the sampling methods used in different mining environments. If groundwater samples are collected from discrete depths within open boreholes, water in those boreholes have the opportunity to move up or down in response to the forces that drive groundwater flow, whether they be hydraulic gradients, gas pressures, or density differences associated with variations in salinity. The use of Br/Cl ratios, for example, can be used to determine if there is active flow into, or out of, the boreholes through open discontinuities in the rock mass (i.e., short-circuiting). Natural groundwater quality can also be affected to varying degrees by mixing with drilling fluids. The combined use of inorganic chemistry and stable isotopes can be used effectively to identify dilution signals and map the dilution patterns through a range of fresh, brackish and saline water types. The stable isotopes of oxygen and hydrogen are nearly ideal natural tracers of water, but situations occur when deep groundwater samples can plot to the left of the meteoric water line as a result of isotopic exchange between meteoric water and silicate rock in near-surface environments at low temperatures. These and other examples are considered in the practical application of aqueous geochemistry in helping to map flow systems in fractured-rock systems.

Seafloor bathymetry and gravity from the ALBACORE marine seismic experiment offshore southern California

NASA Astrophysics Data System (ADS)

Shintaku, N.; Weeraratne, D. S.; Kohler, M. D.

2010-12-01

Although the North America side of the plate boundary surrounding the southern California San Andreas fault region is well studied and instrumented, the Pacific side of this active tectonic boundary is poorly understood. In order to better understand this complex plate boundary offshore, its microplate structures, deformation, and the California Borderland formation, we have recently conducted the first stage of a marine seismic experiment (ALBACORE - Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) deploying 34 ocean bottom seismometers offshore southern California in August 2010. We present preliminary data consisting of seafloor bathymetry and free air gravity collected from this experiment. We present high-resolution maps of bathymetry and gravity from the ALBACORE experiment compiled with previous ship track data obtained from the NGDC (National Geophysical Data Center) and the USGS. We use gravity data from Smith and Sandwell and study correlations with ship track bathymetry data for the features described below. We observe new seafloor geomorphological features far offshore and within the Borderland. Steep canyon walls which line the edges of the Murray fracture zone with possible volcanic flows along the canyon floor were mapped by multibeam bathymetry for the first time. Deep crevices juxtaposed with high edifices of intensely deformed plateaus indicate high strain deformation along the arcuate boundary of the Arguello microplate. Small volcanic seamounts are mapped which straddle the Ferrelo fault (Outer Borderland) and San Pedro fault (Inner Borderland), and appear to exhibit fracture and fault displacement of a portion of the volcanic centers in a left-lateral sense. A large landslide is also imaged extending approximately 6 miles in length and 3 miles in width in the Santa Cruz basin directly south of Santa Rosa Island. Deformation associated with capture of Arguello and Patton microplates by the Pacific plate is studied as well as deformation surrounding the Murray fracture zone near the California shore. Faults in the Borderland identified by improved sea floor mapping may indicate offshore earthquake sources.

Sports nuclear medicine. Bone imaging for lower extremity pain in athletes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brill, D.R.

Increased participation in sports by the general public has led to an increase in sports-induced injuries, including stress fractures, shin splints, arthritis, and a host of musculotendinous maladies. Bone scintigraphy with Tc-99m MDP has been used with increasing frequency in detecting stress fractures, but this study can miss certain important conditions and detect other lesions of lesser clinical significance. This paper demonstrates the spectrum of findings on bone scanning in nonacute sports trauma and offers suggestions for the optimal use of Tc-99m MDP for detecting the causes of lower extremity pain in athletes.

Hydraulic fracture monitoring in hard rock at 410 m depth with an advanced fluid-injection protocol and extensive sensor array

NASA Astrophysics Data System (ADS)

Zang, Arno; Stephansson, Ove; Stenberg, Leif; Plenkers, Katrin; Specht, Sebastian; Milkereit, Claus; Schill, Eva; Kwiatek, Grzegorz; Dresen, Georg; Zimmermann, Günter; Dahm, Torsten; Weber, Michael

2017-02-01

In this paper, an underground experiment at the Äspö Hard Rock Laboratory (HRL) is described. Main goal is optimizing geothermal heat exchange in crystalline rock mass at depth by multistage hydraulic fracturing with minimal impact on the environment, that is, seismic events. For this, three arrays with acoustic emission, microseismicity and electromagnetic sensors are installed mapping hydraulic fracture initiation and growth. Fractures are driven by three different water injection schemes (continuous, progressive and pulse pressurization). After a brief review of hydraulic fracture operations in crystalline rock mass at mine scale, the site geology and the stress conditions at Äspö HRL are described. Then, the continuous, single-flow rate and alternative, multiple-flow rate fracture breakdown tests in a horizontal borehole at depth level 410 m are described together with the monitoring networks and sensitivity. Monitoring results include the primary catalogue of acoustic emission hypocentres obtained from four hydraulic fractures with the in situ trigger and localizing network. The continuous versus alternative water injection schemes are discussed in terms of the fracture breakdown pressure, the fracture pattern from impression packer result and the monitoring at the arrays. An example of multistage hydraulic fracturing with several phases of opening and closing of fracture walls is evaluated using data from acoustic emissions, seismic broad-band recordings and electromagnetic signal response. Based on our limited amount of in situ tests (six) and evaluation of three tests in Ävrö granodiorite, in the multiple-flow rate test with progressively increasing target pressure, the acoustic emission activity starts at a later stage in the fracturing process compared to the conventional fracturing case with continuous water injection. In tendency, also the total number and magnitude of acoustic events are found to be smaller in the progressive treatment with frequent phases of depressurization.

Contaminant behavior in fractured sedimentary rocks: Seeing the fractures that matter

NASA Astrophysics Data System (ADS)

Parker, B. L.

2017-12-01

High resolution spatial sampling of continuous cores from sites contaminated with chlorinated solvents over many decades was used as a strategy to quantify mass stored in low permeability blocks of rock between hydraulically active fractures. Given that core and geophysical logging methods cannot distinguish between hydraulically active fractures and those that do not transmit water, these samples were informed by careful logging of visible fracture features in the core with sample spacing determined by modelled diffusion transport distances given rock matrix properties and expected ages of contamination. These high resolution contaminant concentration profiles from long term contaminated sites in sedimentary rock showed evidence of many more hydraulically active fractures than indicated by the most sophisticated open-hole logging methods. Fracture density is an important attribute affecting fracture connectivity and influencing contaminant plume evolution in fractured porous sedimentary rock. These contaminant profile findings were motivation to find new borehole methods to directly measure hydraulically active fracture occurrence and flux to corroborate the long term "DNAPL tracer experiment" results. Improved sensitivity is obtained when boreholes are sealed using flexible fabric liners (FLUTeTM technology) and various sensor options are deployed in the static water columns used to inflate these liners or in contact with the borehole wall behind the liners. Several methods rely on high resolution temperature measurements of ambient or induced temperature variability such as temperature vector probes (TVP), fiber optic cables for distributed temperature sensing (DTS), both using active heat; packer testing, point dilution testing and groundwater flux measurements between multiple straddle packers to account for leakage. In all cases, numerous hydraulically active fractures are identified over 100 to 300 meters depth, with a large range in transmissivities and hydraulic apertures to inform discrete fracture flow and transport models. 3-D field mapping of decades-old contaminant plumes in sedimentary aquifers shows that numerous hydraulically active fractures are needed to reproduce observed plume concentration distributions and allow targeted monitoring and remediation.

FracPaQ: A MATLAB™ toolbox for the quantification of fracture patterns

NASA Astrophysics Data System (ADS)

Healy, David; Rizzo, Roberto E.; Cornwell, David G.; Farrell, Natalie J. C.; Watkins, Hannah; Timms, Nick E.; Gomez-Rivas, Enrique; Smith, Michael

2017-02-01

The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, and spatial distributions often exhibit some kind of order. In detail, relationships may exist among the different fracture attributes, e.g. small fractures dominated by one orientation, larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture attributes and patterns. This paper describes FracPaQ, a new open source, cross-platform toolbox to quantify fracture patterns, including distributions in fracture attributes and their spatial variation. Software has been developed to quantify fracture patterns from 2-D digital images, such as thin section micrographs, geological maps, outcrop or aerial photographs or satellite images. The toolbox comprises a suite of MATLAB™ scripts based on previously published quantitative methods for the analysis of fracture attributes: orientations, lengths, intensity, density and connectivity. An estimate of permeability in 2-D is made using a parallel plate model. The software provides an objective and consistent methodology for quantifying fracture patterns and their variations in 2-D across a wide range of length scales, rock types and tectonic settings. The implemented methods presented are inherently scale independent, and a key task where applicable is analysing and integrating quantitative fracture pattern data from micro-to macro-scales. The toolbox was developed in MATLAB™ and the source code is publicly available on GitHub™ and the Mathworks™ FileExchange. The code runs on any computer with MATLAB installed, including PCs with Microsoft Windows, Apple Macs with Mac OS X, and machines running different flavours of Linux. The application, source code and sample input files are available in open repositories in the hope that other developers and researchers will optimise and extend the functionality for the benefit of the wider community.

Analysis of alkyl phosphates in petroleum samples by comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection and post-column Deans switching.

PubMed

Nizio, Katie D; Harynuk, James J

2012-08-24

Alkyl phosphate based gellants used as viscosity builders for fracturing fluids used in the process of hydraulic fracturing have been implicated in numerous refinery-fouling incidents in North America. In response, industry developed an inductively coupled plasma optical emission spectroscopy (ICP-OES) based method for the analysis of total volatile phosphorus in distillate fractions of crude oil; however, this method is plagued by poor precision and a high limit of detection (0.5±1μg phosphorus mL(-1)). Furthermore this method cannot provide speciation information, which is critical for developing an understanding of the challenge of alkyl phosphates at a molecular level. An approach using comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection (GC×GC-NPD) and post-column Deans switching is presented. This method provides qualitative and quantitative profiles of alkyl phosphates in industrial petroleum samples with increased precision and at levels comparable to or below those achievable by ICP-OES. A recovery study in a fracturing fluid sample and a profiling study of alkyl phosphates in four recovered fracturing fluid/crude oil mixtures (flowback) are also presented. Copyright © 2012 Elsevier B.V. All rights reserved.

Detection of Fracture Patterns Within the Southern Portion of a Residential Complex (Tepozanes), Los Reyes-La Paz County (Edo. de Mexico)

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Arango, C.; Tejero, A.; Cifuentes, G.; Hernandez, E.

2008-12-01

Most of the urban zone within the Valley of Mexico is built on top of the sediments of the ancient lakes of Chalco, Xochimilco, Mexico, Texcoco, Xaltocan and Zumpango. The sediments that cover this great valley are mainly composed by highly saturated clay-sandy materials; which offer a weak resistance to the constructions built on top. In addition, the increasing need of water supply for the population living in the valley (~22 million inhabitants) has weakened the main groundwater aquifers. This has lead to a differentiated subsidence and collapse of buildings, habitation units and roads. These effects put in a serious risk the inhabitants and the infrastructure of the city. As an example, we present a case of an area located in a densely populated zone, within a low-income residential complex denominated Tepozanes. This is located in the Los Reyes-La Paz County (Mexico State), towards the southeastern portion of the Valley of Mexico. The area is geologically limited by the Chimalhuacan Hill to the N, by the Santa Catarina volcanic range to the S. The previously mentioned effects are evident in the constructions of some buildings, where an exposed fracture is found in the NE-SW direction. This feature is affecting the structure of one of them in the residential complex, where the fracture runs underneath. A geophysical study was proposed to characterize the subsoil and to define the fracturing patterns in the zone. The electrical resistivity tomography (ETR) method employing the capacitive and galvanic modes was used to define the fracturing patters and the position at depth of the saturated layers, which might affect the Residential buildings. As a complement, GPR (Ground Penetrating Radar) profiles were carried out on the same profiles to correlate the information obtained from the ETR capacitive method which has a better resolution in the shallower zone. The computed results show that the buildings foundations were set on top of a high resistivity layer (~1000 Ohm-m), with variable thickness (5 m to 20 m). This layer depicts important discontinuities that can be associated to fractures. Low resistivity sediments lie on top of the resistive horizon. This feature corresponds to saturated sediments (clays and sands) that due to the water flow tend to form areas with low mechanical resistance and vey high compressibility, producing subsidence, following the fracture pattern in the resistive layer. The GPR study defined the presence of small fractures to depths ranging between 1 m and 3 m, which can be correlated with the information provided by the capacitive method. A subsidence map was produced for the studied zone. The fracture pattern is found in the SW-NE direction, affecting the residential complex at the surrounding. Three exploratory wells were drilled within the studied area. The stratigraphy obtained correlated well with the electrical models.

First Rib Fracture Resulting in Horner's Syndrome.

PubMed

Lin, You-Cheng; Chuang, Ming-Tsung; Hsu, Chin-Hao; Tailor, Al-Rahim Abbasali; Lee, Jung-Shun

2015-12-01

First rib fractures and traumatic Horner's syndrome are both quite rare, which can make it difficult to properly diagnose the combination of these 2 conditions in the emergency department. These conditions may be associated with severe medical emergencies, such as ongoing carotid dissection. We present the case of a 33-year-old man who sustained fractures to his right second, third, and fourth ribs and a delay in the diagnosis of left Horner's syndrome after he was involved in a traffic accident. Left Horner's syndrome was caused by a left transverse fracture of the first rib. This fracture was not detected on chest radiographs and required a 3-dimensional reconstructed neck computed tomography scan for detection. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: In the diagnosis of carotid artery dissection, conventional angiography is the criterion standard but is considered invasive. CTA is less invasive, time-saving, and can show more anatomic structures in the neck in addition to the carotid arteries. It is a good screening diagnostic modality in the traumatology department. Although the treatments for Horner's syndrome and first rib fracture are conservative, the early diagnosis of both conditions can resolve the anxiety and uncertainty experienced by both doctors and patients. Copyright © 2015 Elsevier Inc. All rights reserved.

The influence of secondary reconstruction slice thickness on NewTom 3G cone beam computed tomography-based radiological interpretation of sheep mandibular condyle fractures.

PubMed

Sirin, Yigit; Guven, Koray; Horasan, Sinan; Sencan, Sabri; Bakir, Baris; Barut, Oya; Tanyel, Cem; Aral, Ali; Firat, Deniz

2010-11-01

The objective of this study was to examine the diagnostic accuracy of the different secondary reconstruction slice thicknesses of cone beam computed tomography (CBCT) on artificially created mandibular condyle fractures. A total of 63 sheep heads with or without condylar fractures were scanned with a NewTom 3G CBCT scanner. Multiplanar reformatted (MPR) views in 0.2-mm, 1-mm, 2-mm, and 3-mm secondary reconstruction slice thicknesses were evaluated by 7 observers. Inter- and intraobserver agreements were calculated with weighted kappa statistics. The receiver operating characteristic (ROC) curve analysis was used to statistically compare the area under the curve (AUC) of each slice thickness. The kappa coefficients varied from fair and to excellent. The AUCs of 0.2-mm and 1-mm slice thicknesses were found to be significantly higher than those of 2 mm and 3 mm for some type of fractures. CBCT was found to be accurate in detecting all variants of fractures at 0.2 mm and 1 mm. However, 2-mm and 3-mm slices were not suitable to detect fissure, complete, and comminuted types of mandibular condyle fractures. Copyright © 2010 Mosby, Inc. All rights reserved.

Damage characterization on human femur bone by means of ultrasonics and acoustic emission

NASA Astrophysics Data System (ADS)

Strantza, M.; Polyzos, D.; Louis, O.; Boulpaep, F.; Van Hemelrijck, D.; Aggelis, D. G.

2015-07-01

Human bone tissue is characterized as a material with high brittleness. Due to this nature, visible signs of cracking are not easy to be detected before final failure. The main objective of this work is to investigate if the acoustic emission (AE) technique can offer valuable insight to the fracture process of human femur specimens as in other engineering materials characterization. This study describes the AE activity during fracture of whole femur bones under flexural load. Before fracture, broadband AE sensors were used in order to measure parameters like wave velocity dispersion and attenuation. Waveform parameters like the duration, rise time and average frequency, were also examined relatively to the propagation distance as a preparation for the AE monitoring during fracture. After the ultrasonic study, the samples were partly cast in concrete and fixed as cantilevers. A point load was applied on the femur head, which due to the test geometry resulted in a combination of two different patterns of fracture, bending and torsion. Two AE broadband sensors were placed in different points of the sample, one near the fixing end and the other near the femur head. Preliminary analysis shows that parameters like the number of acquired AE signals and their amplitude are well correlated with the load history. Furthermore, the parameters of rise time and frequency can differentiate the two fracture patterns. Additionally, AE allows the detection of the load at the onset of fracture from the micro-cracking events that occur at the early loading stages, allowing monitoring of the whole fracture process. Parameters that have been used extensively for monitoring and characterization of fracture modes of engineering materials seem to poses characterization power in the case of bone tissue monitoring as well.

Secondary contributors to bone loss in osteoporosis related hip fractures.

PubMed

Edwards, B J; Langman, C B; Bunta, A D; Vicuna, M; Favus, M

2008-07-01

Osteoporosis treatment of patients with hip fractures is necessary to prevent subsequent fractures. Secondary causes for bone loss are present in more than 80% of patients with hip fractures, and therefore, assessment of Vitamin D status, disorders in calcium absorption and excretion, monoclonal gammopathies, and renal function should be performed. Identifying and managing these disorders will improve detection and enhance treatment aimed at reducing the risk of recurrent fractures in older adults. The purpose of this study was to determine the prevalence of disorders affecting bone and mineral metabolism in individuals with osteoporotic hip fractures. Community dwelling individuals with hip fractures (HFx) 50 years of age and older. Assessment for vitamin D, renal and parathyroid status, calcium absorption, and plasma cell disorders. Of 157 HFx, mean age 70 +/- 10 years, HFx had higher creatinine (p = 0.002, 95% C.I. -0.09, 0.05); lower 25 OH vitamin D (p = 0.019, 95% C.I. 6.5, 2.7), albumin (p = 0.007, 95% C.I. 0.36, 0.009), and 24-h urine calcium (p = 0.024, 95% CI 51, 21) as compared to controls. More than 80% of HFx had at least one previously undiagnosed condition, with vitamin D insufficiency (61%), chronic kidney disease (16%) (CKD), monoclonal gammopathy (6%), and low calcium absorption (5%) being the most common. One case each of multiple myeloma and solitary plasmocytoma were identified. Osteoporosis treatment of HFx is necessary to prevent subsequent fractures. Secondary causes for bone loss are remarkably common in HFx; therefore, assessment of vitamin D status, disorders in calcium absorption and excretion, protein electrophoresis, and renal function should be performed. Identifying and correcting these disorders will improve detection and enhance treatment aimed at reducing the risk of recurrent fractures in older adults.

A multi-scale experimental and simulation approach for fractured subsurface systems

NASA Astrophysics Data System (ADS)

Viswanathan, H. S.; Carey, J. W.; Frash, L.; Karra, S.; Hyman, J.; Kang, Q.; Rougier, E.; Srinivasan, G.

2017-12-01

Fractured systems play an important role in numerous subsurface applications including hydraulic fracturing, carbon sequestration, geothermal energy and underground nuclear test detection. Fractures that range in scale from microns to meters and their structure control the behavior of these systems which provide over 85% of our energy and 50% of US drinking water. Determining the key mechanisms in subsurface fractured systems has been impeded due to the lack of sophisticated experimental methods to measure fracture aperture and connectivity, multiphase permeability, and chemical exchange capacities at the high temperature, pressure, and stresses present in the subsurface. In this study, we developed and use microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. In addition we have developed high fidelity fracture propagation and discrete fracture network flow models to simulate these fractured systems. We also have developed reduced order models of these fracture simulators in order to conduct uncertainty quantification for these systems. We demonstrate an integrated experimental/modeling approach that allows for a comprehensive characterization of fractured systems and develop models that can be used to optimize the reservoir operating conditions over a range of subsurface conditions.

Laboratory testing on infiltration in single synthetic fractures

NASA Astrophysics Data System (ADS)

Cherubini, Claudia; Pastore, Nicola; Li, Jiawei; Giasi, Concetta I.; Li, Ling

2017-04-01

An understanding of infiltration phenomena in unsaturated rock fractures is extremely important in many branches of engineering for numerous reasons. Sectors such as the oil, gas and water industries are regularly interacting with water seepage through rock fractures, yet the understanding of the mechanics and behaviour associated with this sort of flow is still incomplete. An apparatus has been set up to test infiltration in single synthetic fractures in both dry and wet conditions. To simulate the two fracture planes, concrete fractures have been moulded from 3D printed fractures with varying geometrical configurations, in order to analyse the influence of aperture and roughness on infiltration. Water flows through the single fractures by means of a hydraulic system composed by an upstream and a downstream reservoir, the latter being subdivided into five equal sections in order to measure the flow rate in each part to detect zones of preferential flow. The fractures have been set at various angles of inclination to investigate the effect of this parameter on infiltration dynamics. The results obtained identified that altering certain fracture parameters and conditions produces relevant effects on the infiltration process through the fractures. The main variables influencing the formation of preferential flow are: the inclination angle of the fracture, the saturation level of the fracture and the mismatch wavelength of the fracture.

Interpretation of VLF-EM & VLF-R data using tipper and impedance analyses: A case study from Candi Umbul-Telomoyo, Magelang, Indonesia

NASA Astrophysics Data System (ADS)

Prastyani, Erina; Niasari, Sintia Windhi

2017-07-01

The goal of all geophysical survey techniques is to image the properties of the Earth's subsurface. Very Low Frequency (VLF) is one of the geophysical survey technique that has been commonly used for ore exploration and mapping faults or fracture zones. Faults or fracture zones are necessary components in providing the fluid pathway in geothermal systems. The Candi Umbul-Telomoyo is one of the geothermal prospect sites in Indonesia, which is located in Magelang, Central Java. Recent studies hypothesized that this site was an outflow area of Telomoyo volcano geothermal complex. We used the VLF-EM and VLF-R techniques to infer faults or fracture zones that might be a path for geothermal fluids in the Candi Umbul-Telomoyo. From the measurements, we got tilt angle, ellipticity, primary and secondary magnetic fieldfor VLF-EM data; and apparent resistivity, phase angle, electric and magnetic field for VLF-R data. To interpret the data, we used tipper and impedance analyses. The result of both analyses show similarities in the directions and positions of anomalous current concentrations. We conclude these anomalous current concentrations as faults. Our interpretation is agreeing with the Geologic Map of the Semarang and Magelang Quadrangles that shows the expected fault beneath the Mt. Telomoyo.

Chemical analyses (raw laboratory data) and locality index maps of the Confederate Gulch area, Broadwater and Meagher Counties, Montana

USGS Publications Warehouse

,

1975-01-01

Analysis of the side looking airborn radar imagery of Massachusetts, Connecticut and Rhode Island indicates that radar shows the topography in great detail. Since bedrock geologic features are frequently expressed in the topography the radar lends itself to geologic interpretation. The radar was studied by comparisons with field mapped geologic data first at a scale of approximately 1:125,000 and then at a scale of 1:500,000. The larger scale comparison revealed that faults, minor faults, joint sets, bedding and foliation attitudes, lithology and lithologic contacts all have a topographic expression interpretable on the imagery. Surficial geologic features were far less visible on the imagery over most of the area studied. The smaller scale comparisons revealed a pervasive, near orthogonal fracture set cutting all types and ages of rock and trending roughly N40?E and N30?W. In certain places the strike of bedding and foliation attitudes and some lithologic Contacts were visible in addition to the fractures. Fracturing in southern New England is apparently far more important than has been previously recognized. This new information, together with the visibility of many bedding and foliation attitudes and lithologic contacts, indicates the importance of radar imagery in improving the geologic interpretation of an area.

Archuleta County CO Lineaments

DOE Data Explorer

Richard E. Zehner

2012-01-01

This layer traces apparent topographic and air-photo lineaments in the area around Pagosa springs in Archuleta County, Colorado. It was made in order to identify possible fault and fracture systems that might be conduits for geothermal fluids. Geothermal fluids commonly utilize fault and fractures in competent rocks as conduits for fluid flow. Geothermal exploration involves finding areas of high near-surface temperature gradients, along with a suitable plumbing system that can provide the necessary permeability. Geothermal power plants can sometimes be built where temperature and flow rates are high. To do this, georeferenced topographic maps and aerial photographs were utilized in an existing GIS, using ESRI ArcMap 10.0 software. The USA_Topo_Maps and World_Imagery map layers were chosen from the GIS Server at server.arcgisonline.com, using a UTM Zone 13 NAD27 projection. This line shapefile was then constructed over that which appeared to be through-going structural lineaments in both the aerial photographs and topographic layers, taking care to avoid manmade features such as roads, fence lines, and right-of-ways. These lineaments may be displaced somewhat from their actual location, due to such factors as shadow effects with low sun angles in the aerial photographs. Note: This shape file was constructed as an aid to geothermal exploration in preparation for a site visit for field checking. We make no claims as to the existence of the lineaments, their location, orientation, and nature.

Joint Use of ERT, Tracer, and Numerical Techniques to Image Preferential Flow Paths in a Fractured Granite Aquifer

NASA Astrophysics Data System (ADS)

Sanaga, S.; Vijay, S.; Kbvn, P.; Peddinti, S. R.; P S L, S.

2017-12-01

Fractured geologic media poses formidable challenges to hydrogeologists due of the strenuous mapping of fracture-matrix system and quantification of flow and transport processes. In this research, we demonstrated the efficacy of tracer-ERT studies coupled with numerical simulations to delineate preferential flow paths in a fractured granite aquifer of Deccan traps in India. A series of natural gradient saline tracer experiments were conducted from a depth window of 18 to 22 m in an injection well located inside the IIT Hyderabad campus. Tracer migration was monitored in a time-lapse mode using two cross-sectional surface ERT profiles placed in the direction of flow gradient. Dynamic changes in sub-surface electrical properties inferred via resistivity anomalies were used to highlight preferential flow paths of the study area. ERT-derived tracer breakthrough curves were in agreement with geochemical sample measurements (R2=0.74). Fracture geometry and hydraulic properties derived from ERT and pumping tests were then used to evaluate two mathematical conceptualizations that are relevant to fractured aquifers. Results of numerical analysis conclude that a dual continuum model that combines matrix and fracture systems through a flow exchange term has outperformed equivalent continuum model in reproducing tracer concentrations at the monitoring wells (evident by decrease in RMSE from 199 mg/l to 65 mg/l). A sensitivity analysis of the model parameters reveals that spatial variability in hydraulic conductivity, local-scale dispersion, and flow exchange at fracture-matrix interface have a profound effect on model simulations. Keywords: saline tracer, ERT, fractured granite, groundwater, preferential flow, numerical simulation

Studying physical properties of deformed intact and fractured rocks by micro-scale hydro-mechanical-seismicity model

NASA Astrophysics Data System (ADS)

Raziperchikolaee, Samin

The pore pressure variation in an underground formation during hydraulic stimulation of low permeability formations or CO2 sequestration into saline aquifers can induce microseismicity due to fracture generation or pre-existing fracture activation. While the analysis of microseismic data mainly focuses on mapping the location of fractures, the seismic waves generated by the microseismic events also contain information for understanding of fracture mechanisms based on microseismic source analysis. We developed a micro-scale geomechanics, fluid-flow and seismic model that can predict transport and seismic source behavior during rock failure. This model features the incorporation of microseismic source analysis in fractured and intact rock transport properties during possible rock damage and failure. The modeling method considers comprehensive grains and cements interaction through a bonded-particle-model. As a result of grain deformation and microcrack development in the rock sample, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. In addition, geometric description of the complex pore structure is regenerated to predict fluid flow behavior of fractured samples. Numerical experiments are conducted for different intact and fractured digital rock samples, representing various mechanical behaviors of rocks and fracture surface properties, to consider their roles on seismic and transport properties of rocks during deformation. Studying rock deformation in detail provides an opportunity to understand the relationship between source mechanism of microseismic events and transport properties of damaged rocks to have a better characterizing of fluid flow behavior in subsurface formations.

The influence of a reverse-reactivated normal fault on natural fracture geometries and relative chronologies at Castle Cove, Otway Basin

NASA Astrophysics Data System (ADS)

Debenham, Natalie; King, Rosalind C.; Holford, Simon P.

2018-07-01

Despite the ubiquity of normal faults that have undergone compressional inversion, documentation of the structural history of natural fractures around these structures is limited. In this paper, we investigate the geometries and relative chronologies of natural fractures adjacent to a reverse-reactivated normal fault, the Castle Cove Fault in the Otway Basin, southeast Australia. Local variations in strain resulted in greater deformation within the fault damage zone closer to the fault. Structural mapping within the damage zone reveals a complex tectonic history recording both regional and local perturbations in stress and a total of 11 fracture sets were identified, with three sets geometrically related to the Castle Cove Fault. The remaining fracture sets formed in response to local stresses at Castle Cove. Rifting in the late Cretaceous resulted in normal movement of the Castle Cove Fault and associated rollover folding, and the formation of the largest fracture set. Reverse-reactivation of the fault and associated anticlinal folding occurred during late Miocene to Pliocene compression. Rollover folding may have provided structural traps if seals were not breached by fractures, however anticlinal folding likely post-dated the main episodes of hydrocarbon generation and migration in the region. This study highlights the need to conduct careful reconstruction of the structural histories of fault zones that experienced complex reactivation histories when attempting to define off-fault fluid flow properties.

A joint TEM-HLEM geophysical approach to borehole sitting in deeply weathered granitic terrains.

PubMed

Meju, M A; Fontes, S L; Ulugergerli, E U; La Terra, E F; Germano, C R; Carvalho, R M

2001-01-01

The accurate location of aquiferous fracture zones in granite beneath a > 50 m thick weathered mantle in semi-arid regions is a major hydrogeological problem. It is expected that the zone of intensive fracturing will be more susceptible to weathering and thus be characterized by the thickest development of saprolite, a good electrically conductive target for deep-probing electromagnetic systems. The single-loop transient electromagnetic (TEM) technique is well known to have the capability for detecting concealed steep mineralized targets in mining environments and can be adapted to this hydrogeological problem. We propose that combining the conventional frequency-domain horizontal-loop electromagnetic (HLEM) and single-loop TEM is an effective practical approach to locating concealed aquiferous fracture zones. In the supporting case studies presented here, we deployed multifrequency HLEM profiling (with 50 m transmitter-receiver separation) and TEM soundings with contiguous 10 or 20 m sided loops along the survey lines in a granitic terrain affected by deep (> 50 m) weathering in northeast Brazil. A somewhat layered structure consisting of resistive hardpan/leached zone, conductive saprolite, and resistive basement is identifiable in the typical TEM depth sounding data. We obtained coincident HLEM and TEM anomalies at all the sites, enabling a relatively straightforward selection of potential drilling positions. Simple resistivity-depth transformation of the TEM data was done for each site, yielding an approximate section from which drilling depths were estimated. All of the boreholes located were successful. Although our results appear to indicate that the single-loop TEM method could be used independently for borehole sitting in deeply weathered granitic terrains and that the weathering profile over granite can be mapped using TEM depth soundings of appropriate observational bandwidth, we recommend a joint electromagnetic approach for optimal well sitting.

Streaming potential modeling in fractured rock: Insights into the identification of hydraulically active fractures

NASA Astrophysics Data System (ADS)

Roubinet, D.; Linde, N.; Jougnot, D.; Irving, J.

2016-05-01

Numerous field experiments suggest that the self-potential (SP) geophysical method may allow for the detection of hydraulically active fractures and provide information about fracture properties. However, a lack of suitable numerical tools for modeling streaming potentials in fractured media prevents quantitative interpretation and limits our understanding of how the SP method can be used in this regard. To address this issue, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid flow and associated self-potential problems in fractured rock. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interactions. This implies that fractures associated with strong SP amplitudes are likely to be hydraulically conductive, attracting fluid flow from the surrounding matrix.

Hot and Steamy Fractures in the Philippines: The Geological Characterization and Permeability Evaluation of Fractures in the Southern Negros Geothermal Field, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, L. R.; Holdsworth, R.; McCaffrey, K. J. W.; Dempsey, E. D.; Walker, R. J.; Gluyas, J.; Reyes, J. K.

2016-12-01

Fluid flow pathway characterization is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.

Hot and steamy fractures in the Philippines: the characterisation and permeability evaluation of fractures of the Southern Negros Geothermal Field, Negros Oriental, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, Loraine; Holdsworth, Robert; McCaffrey, Kenneth; Dempsey, Eddie; Walker, Richard; Gluyas, Jon; Reyes, Jonathan

2017-04-01

Fluid flow pathway characterisation is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.

Ultrasound-guided diagnosis of fractures of the distal forearm in children.

PubMed

Herren, C; Sobottke, R; Ringe, M J; Visel, D; Graf, M; Müller, D; Siewe, J

2015-06-01

Distal radius and forearm fractures are injuries that are frequently seen in trauma surgery outpatient clinics. Usually, the wrist is X-rayed in 2 planes as standard diagnostic procedure. In contrast, we evaluate in our study the accuracy of ultrasonography (US) in diagnosing these fractures. This prospective study includes the patients who presented at two trauma surgery clinics with a presumptive diagnosis of distal radius or forearm fracture between January and December 2012. After a clinical examination, US imaging of the distal forearm was first carried out on 6 standardized planes followed by radiographs of the wrist made in two planes. The age limit was set at the end of 11 years. In total, 201 patients between 4 and 11 years of age were recruited with an average age of 9.5 years at the time of the trauma. There were 104 (51.7%) fractures distributed as follows: 89 (85.9%) injuries of the distal radius, 9 (8.7%) injuries of the distal ulna, and 6 (5.8%) combined injuries (radius and ulna). Sixty-five greenstick fractures were detected. Surgery was necessary in 34 cases. Specificity and sensitivity of ultrasound diagnosis were 99.5%. Ultrasound imaging is suitable to demonstrate fractures of the distal forearm. It is a highly sensitive procedure in detecting distal forearm fractures. In our opinion, a negative result in ultrasound may reduce the need for further radiographs in children with distal forearm lesions. But in any doubtful situation the need for conventional radiographs remains. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Clinical and Radiologic Predictive Factors of Rib Fractures in Outpatients With Chest Pain.

PubMed

Zhang, Liang; McMahon, Colm J; Shah, Samir; Wu, Jim S; Eisenberg, Ronald L; Kung, Justin W

To identify the clinical and radiologic predictive factors of rib fractures in stable adult outpatients presenting with chest pain and to determine the utility of dedicated rib radiographs in this population of patients. Following Institutional Review Board approval, we performed a retrospective review of 339 consecutive cases in which a frontal chest radiograph and dedicated rib series had been obtained for chest pain in the outpatient setting. The frontal chest radiograph and dedicated rib series were sequentially reviewed in consensus by two fellowship-trained musculoskeletal radiologists blinded to the initial report. The consensus interpretation of the dedicated rib series was used as the gold standard. Multiple variable logistic regression analysis assessed clinical and radiological factors associated with rib fractures. Fisher exact test was used to assess differences in medical treatment between the 2 groups. Of the 339 patients, 53 (15.6%) had at least 1 rib fracture. Only 20 of the 53 (37.7%) patients' fractures could be identified on the frontal chest radiograph. The frontal chest radiograph had a sensitivity of 38% and specificity of 100% when using the rib series as the reference standard. No pneumothorax, new mediastinal widening or pulmonary contusion was identified. Multiple variable logistic regression analysis of clinical factors associated with the presence of rib fractures revealed a significant association of trauma history (odds ratio 5.7 [p < 0.05]) and age ≥40 (odds radio 3.1 [p < 0.05]). Multiple variable logistic regression analysis of radiographic factors associated with rib fractures in this population demonstrated a significant association of pleural effusion with rib fractures (odds ratio 18.9 [p < 0.05]). Patients with rib fractures received narcotic analgesia in 47.2% of the cases, significantly more than those without rib fractures (21.3%, p < 0.05). None of the patients required hospitalization. In the stable outpatient setting, rib fractures have a higher association with a history of minor trauma and age ≥40 in the adult population. Radiographic findings associated with rib fractures include pleural effusion. The frontal chest radiograph alone has low sensitivity in detecting rib fractures. The dedicated rib series detected a greater number of rib fractures. Although no patients required hospitalization, those with rib fractures were more likely to receive narcotic analgesia. Copyright © 2018 Elsevier Inc. All rights reserved.

Colloidal crystal templated molecular imprinted polymer for the detection of 2-butoxyethanol in water contaminated by hydraulic fracturing.

PubMed

Dai, Jingjing; Vu, Danh; Nagel, Susan; Lin, Chung-Ho; Fidalgo de Cortalezzi, Maria

2017-12-06

The authors describe a molecularly imprinted polymer (MIP) that enables detection of 2-butoxyethanol (2BE), a pollutant associated with hydraulic fracturing contamination. Detection is based on a combination of a colloidal crystal templating and a molecular imprinting. The MIPs are shown to display higher binding capacity for 2BE compared to non-imprinted films (NIPs), with imprinting efficiencies of ∼ 2. The tests rely on the optical effects that are displayed by the uniformly ordered porous structure of the material. The reflectance spectra of the polymer films have characteristic Bragg peaks whose location varies with the concentration of 2BE. Peaks undergo longwave red shifts up to 50 nm on exposure of the MIP to 2BE in concentrations in the range from 1 ppb to 100 ppm. This allows for quantitative estimates of the 2BE concentrations present in aqueous solutions. The material is intended for use in the early detection of contamination at hydraulic fracturing sites. Graphical abstract Molecularly imprinted polymers (MIPs) sensor with the sensing ability on reflectance spectra responding to the presence of 2-butoxyethanol (2BE) for early detection of hydraulic fracking contamination.

Creation of a High-fidelity, Low-cost Pediatric Skull Fracture Ultrasound Phantom.

PubMed

Soucy, Zachary P; Mills, Lisa; Rose, John S; Kelley, Kenneth; Ramirez, Francisco; Kuppermann, Nathan

2015-08-01

Over the past decade, point-of-care ultrasound has become a common tool used for both procedures and diagnosis. Developing high-fidelity phantoms is critical for training in new and novel point-of-care ultrasound applications. Detecting skull fractures on ultrasound imaging in the younger-than-2-year-old patient is an emerging area of point-of-care ultrasound research. Identifying a skull fracture on ultrasound imaging in this age group requires knowledge of the appearance and location of sutures to distinguish them from fractures. There are currently no commercially available pediatric skull fracture models. We outline a novel approach to building a cost-effective, simple, high-fidelity pediatric skull fracture phantom to meet a unique training requirement. © 2015 by the American Institute of Ultrasound in Medicine.

Micro-imager View: Layers in 'Vera Rubin Ridge,' Mars

NASA Image and Video Library

2017-09-13

This view of "Vera Rubin Ridge" from the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity Mars rover shows multiple sedimentary layers and fracture-filling deposits of minerals. Buried layers of what is now a ridge became fractured, and the fractures were filled with mineral deposits precipitated from underground fluids that moved through the fractures. ChemCam's telescopic Remote Micro-Imager took the 10 component images of this mosaic on July 3, 2017, during the 1,745th Martian day, or sol, of Curiosity's work on Mars. The camera was about 377 feet (115 meters) away from the pictured portion of the ridge. The rover's location at the time, shown in a Sol 1741 traverse map, was west of the place where it began its ascent up the ridge about two months later. The scale bar at lower right indicates how wide a feature 9 inches (22.8 centimeters) in width would look in the middle portion of the scene. https://photojournal.jpl.nasa.gov/catalog/PIA21852

Magnetic resonance imaging of the wrist: bone and cartilage injury.

PubMed

Hayter, Catherine L; Gold, Stephanie L; Potter, Hollis G

2013-05-01

Magnetic resonance imaging (MRI) is particularly useful for imaging the wrist due to its superior soft tissue contrast and ability to detect subtle bone marrow changes and occult fractures. A high field (1.5T or greater) strength, dedicated wrist coil, and high in-plane and through-plane resolution must be utilized to successfully visualize the relatively thin cartilage of the wrist. MRI can be used to detect occult carpal bone fractures, identify complications following scaphoid fractures, and assess for avascular necrosis in the setting in Kienböck's and Preiser's disease. MRI is useful to identify secondary soft tissue and chondral pathology in impaction/impingement syndromes. The use of an intermediate-echo time fast spin echo sequence allows for accurate assessment of articular cartilage, allowing evaluation of chondral wear in the setting of primary osteoarthritis and posttraumatic degenerative arthrosis. MRI is the most sensitive imaging modality for the detection of early inflammatory arthropathies and can detect synovitis, bone marrow edema, and early erosions in the setting of negative radiographs. Copyright © 2012 Wiley Periodicals, Inc.

Can CT imaging of the chest, abdomen, and pelvis identify all vertebral injuries of the thoracolumbar spine without dedicated reformatting?

PubMed

Imran, Jonathan B; Madni, Tarik D; Pruitt, Jeffrey H; Cornelius, Canon; Subramanian, Madhu; Clark, Audra T; Mokdad, Ali A; Rizk, Paul; Minei, Joseph P; Cripps, Michael W; Eastman, Alexander L

2018-07-01

The main objective of this study was to compare detection rates of clinically significant thoracolumbar spine (TLS) fracture between computed tomography (CT) imaging of the chest, abdomen, and spine (CT CAP) and CT for the thoracolumbar spine (CT TL). We retrospectively identified patients at our institution with a TLS fracture over a two-year period that had both CT CAP and reformatted CT TL imaging. The sensitivity of CT CAP to identify fracture was calculated for each fracture type. A total of 516 TLS fractures were identified in 125 patients using reformatted CT TL spine imaging. Overall, 69 of 512 fractures (13%) were missed on CT CAP that were identified on CT TL. Of those, there were no clinically significant missed fractures. CT CAP could potentially be used as a screening tool for clinically significant TLS injuries. Copyright © 2017 Elsevier Inc. All rights reserved.

Water saturation effects on elastic wave attenuation in porous rocks with aligned fractures

NASA Astrophysics Data System (ADS)

Amalokwu, Kelvin; Best, Angus I.; Sothcott, Jeremy; Chapman, Mark; Minshull, Tim; Li, Xiang-Yang

2014-05-01

Elastic wave attenuation anisotropy in porous rocks with aligned fractures is of interest to seismic remote sensing of the Earth's structure and to hydrocarbon reservoir characterization in particular. We investigated the effect of partial water saturation on attenuation in fractured rocks in the laboratory by conducting ultrasonic pulse-echo measurements on synthetic, silica-cemented, sandstones with aligned penny-shaped voids (fracture density of 0.0298 ± 0.0077), chosen to simulate the effect of natural fractures in the Earth according to theoretical models. Our results show, for the first time, contrasting variations in the attenuation (Q-1) of P and S waves with water saturation in samples with and without fractures. The observed Qs/Qp ratios are indicative of saturation state and the presence or absence of fractures, offering an important new possibility for remote fluid detection and characterization.

Spiderweb-like Fractures in Occator Crater

NASA Image and Video Library

2018-01-30

This image shows a complex set of fractures found in the southwestern region of the floor of Occator Crater on Ceres. In this picture, north is at the top. The two intersecting fracture systems (roughly northwest-southeast and southwest-northeast) are part of a larger fault network that extends across Occator's floor. These fractures have been interpreted as evidence that material came up from below and formed a dome shape, as if a piston was pushing Occator's floor from beneath the surface. This may be due to the upwelling of material coming from Ceres' deep interior. An alternative hypothesis is that the deformation is due to volume changes inside a reservoir of icy magma in the shallow subsurface that is in the process of freezing, similar to the change in volume that a bottle of water experiences when put in a freezer. Another set of fractures can be seen parallel to the southwestern wall and is not connected to the Occator fracture network. Dawn took this image during its extended mission on August 17, 2016, from its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometers) above the surface. The image resolution is 120 feet (35 meters) per pixel. The center coordinates are 16 degrees north in latitude and 237 east in longitude. https://photojournal.jpl.nasa.gov/catalog/PIA22091

Role of whole-body 64-slice multidetector computed tomography in treatment planning for multiple myeloma.

PubMed

Razek, Ahmed Abdel Khalek Abdel; Ezzat, Amany; Azmy, Emad; Tharwat, Nehal

2013-08-01

The authors evaluated the role of whole-body 64-slice multidetector computed tomography (WB-MDCT) in treatment planning for multiple myeloma. This was a prospective study of 28 consecutive patients with multiple myeloma (19 men, nine women; age range, 51-73 years; mean age, 60 years) who underwent WB-MDCT and conventional radiography (CR) of the skeleton. The images were interpreted for the presence of bony lesions, medullary lesions, fractures and extraosseous lesions. We evaluated any changes in treatment planning as a result of WB-MDCT findings. WB-MDCT was superior to CR for detecting bony lesions (p=0.001), especially of the spine (p=0.001) and thoracic cage (p=0.006). WB-MDCT upstaged 14 patients, with a significant difference in staging (p=0.002) between WB-MDCT and CR. Medullary involvement either focal (n=6) or diffuse (n=3) had a positive correlation with the overall score (r=0.790) and stage (r=0.618) of disease. Spine fractures were better detected at WB-MDCT (n=4) than at CR (n=2). Extraosseous soft tissue lesions (n=7) were detected only at WB-MDCT. Findings detected at the WB-MDCT led to changes in the patient's treatment plan in 39% of cases. Upstaging of seven patients (25%) altered the medical treatment plan, and four of 28 (14%) patients required additional radiotherapy (7%) and vertebroplasty (7%). We conclude that WB-MDCT has an impact on treatment planning and prognosis in patients with multiple myeloma, as it has high rate of detecting cortical and medullary bone lesions, spinal fracture and extraosseous lesions. This information may alter treatment planning in multiple myeloma due to disease upstaging and detection of spine fracture and extraosseous spinal lesions.

[Algorithms for the identification of hospital stays due to osteoporotic femoral neck fractures in European medical administrative databases using ICD-10 codes: A non-systematic review of the literature].

PubMed

Caillet, P; Oberlin, P; Monnet, E; Guillon-Grammatico, L; Métral, P; Belhassen, M; Denier, P; Banaei-Bouchareb, L; Viprey, M; Biau, D; Schott, A-M

2017-10-01

Osteoporotic hip fractures (OHF) are associated with significant morbidity and mortality. The French medico-administrative database (SNIIRAM) offers an interesting opportunity to improve the management of OHF. However, the validity of studies conducted with this database relies heavily on the quality of the algorithm used to detect OHF. The aim of the REDSIAM network is to facilitate the use of the SNIIRAM database. The main objective of this study was to present and discuss several OHF-detection algorithms that could be used with this database. A non-systematic literature search was performed. The Medline database was explored during the period January 2005-August 2016. Furthermore, a snowball search was then carried out from the articles included and field experts were contacted. The extraction was conducted using the chart developed by the REDSIAM network's "Methodology" task force. The ICD-10 codes used to detect OHF are mainly S72.0, S72.1, and S72.2. The performance of these algorithms is at best partially validated. Complementary use of medical and surgical procedure codes would affect their performance. Finally, few studies described how they dealt with fractures of non-osteoporotic origin, re-hospitalization, and potential contralateral fracture cases. Authors in the literature encourage the use of ICD-10 codes S72.0 to S72.2 to develop algorithms for OHF detection. These are the codes most frequently used for OHF in France. Depending on the study objectives, other ICD10 codes and medical and surgical procedures could be usefully discussed for inclusion in the algorithm. Detection and management of duplicates and non-osteoporotic fractures should be considered in the process. Finally, when a study is based on such an algorithm, all these points should be precisely described in the publication. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Transport and attenuation of carboxylate-modified latex microspheres in fractured rock laboratory and field tracer tests

USGS Publications Warehouse

Becker, M.W.; Reimus, P.W.; Vilks, P.

1999-01-01

Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks of pathogen contamination in drinking water wells. Much has been learned through laboratory and field-scale colloid tracer tests, but progress has been hampered by a lack of consistent tracer testing methodology at different scales and fluid velocities. This paper presents laboratory and field tracer tests in fractured rock that use the same type of colloid tracer over an almost three orders-of-magnitude range in scale and fluid velocity. Fluorescently-dyed carboxylate-modified latex (CML) microspheres (0.19 to 0.98 ??m diameter) were used as tracers in (1) a naturally fractured tuff sample, (2) a large block of naturally fractured granite, (3) a fractured granite field site, and (4) another fractured granite/schist field site. In all cases, the mean transport time of the microspheres was shorter than the solutes, regardless of detection limit. In all but the smallest scale test, only a fraction of the injected microsphere mass was recovered, with the smaller microspheres being recovered to a greater extent than the larger microspheres. Using existing theory, we hypothesize that the observed microsphere early arrival was due to volume exclusion and attenuation was due to aggregation and/or settling during transport. In most tests, microspheres were detected using flow cytometry, which proved to be an excellent method of analysis. CML microspheres appear to be useful tracers for fractured rock in forced gradient and short-term natural gradient tests, but longer residence times may result in small microsphere recoveries.Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks of pathogen contamination in drinking water wells. Much has been learned through laboratory and field-scale colloid tracer tests, but progress has been hampered by a lack of consistent tracer testing methodology at different scales and fluid velocities. This paper presents laboratory and field tracer tests in fractured rock that use the same type of colloid tracer over an almost three orders-of-magnitude range in scale and fluid velocity. Fluorescently-dyed carboxylate-modified latex (CML) microspheres (0.19 to 0.98 ??m diameter) were used as tracers in (1) a naturally fractured tuff sample, (2) a large block of naturally fractured granite, (3) a fractured granite field site, and (4) another fractured granite/schist field site. In all cases, the mean transport time of the microspheres was shorter than the solutes, regardless of detection limit. In all but the smallest scale test, only a fraction of the injected microsphere mass was recovered, with the smaller microspheres being recovered to a greater extent than the larger microspheres. Using existing theory, we hypothesize that the observed microsphere early arrival was due to volume exclusion and attenuation was due to aggregation and/or settling during transport. In most tests, microspheres were detected using flow cytometry, which proved to be an excellent method of analysis. CML microspheres appear to be useful tracers for fractured rock in forced gradient and short-term natural gradient tests, but longer residence times may result in small microsphere recoveries.

ACR Appropriateness Criteria® rib fractures.

PubMed

Henry, Travis S; Kirsch, Jacobo; Kanne, Jeffrey P; Chung, Jonathan H; Donnelly, Edwin F; Ginsburg, Mark E; Heitkamp, Darel E; Kazerooni, Ella A; Ketai, Loren H; McComb, Barbara L; Parker, J Anthony; Ravenel, James G; Restrepo, Carlos Santiago; Saleh, Anthony G; Shah, Rakesh D; Steiner, Robert M; Suh, Robert D; Mohammed, Tan-Lucien H

2014-11-01

Rib fracture is the most common thoracic injury, present in 10% of all traumatic injuries and almost 40% of patients who sustain severe nonpenetrating trauma. Although rib fractures can produce significant morbidity, the diagnosis of associated complications (such as pneumothorax, hemothorax, pulmonary contusion, atelectasis, flail chest, cardiovascular injury, and injuries to solid and hollow abdominal organs) may have a more significant clinical impact. When isolated, rib fractures have a relatively low morbidity and mortality, and failure to detect isolated rib fractures does not necessarily alter patient management or outcome in uncomplicated cases. A standard posteroanterior chest radiograph should be the initial, and often the only, imaging test required in patients with suspected rib fracture after minor trauma. Detailed radiographs of the ribs rarely add additional information that would change treatment, and, although other imaging tests (eg, computed tomography, bone scan) have increased sensitivity for detection of rib fractures, there are little data to support their use. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review process include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Challenges and Solutions for the Integration of Structural and Hydrogeological Understanding of Fracture Systems - Insights from the Olkiluoto Site, Finland

NASA Astrophysics Data System (ADS)

Hartley, L. J.; Aaltonen, I.; Baxter, S. J.; Cottrell, M.; Fox, A. L.; Hoek, J.; Koskinen, L.; Mattila, J.; Mosley, K.; Selroos, J. O.; Suikkanen, J.; Vanhanarkaus, O.; Williams, T. R. N.

2017-12-01

A field site at Olkiluoto in SW Finland has undergone extensive investigations as a location for a deep geological repository for spent nuclear fuel, which is expected to become operational in the early 2020s. Characterisation data comes from 58 deep cored drillholes, a wide variety of geophysical investigations, many outcrops, kilometres of underground mapping and testing in the ONKALO research facility, and groundwater pressure monitoring and sampling in both deep and shallow holes. A primary focus is on the properties of natural fractures and brittle fault zones in the low permeability crystalline rocks at Olkiluoto; an understanding of the flow and transport processes in these features are an essential part of assessing long-term safety of the repository. This presentation will illustrate how different types of source data and cross-disciplinary interpretations are integrated to develop conceptual and numerical models of the fracture system. A model of the brittle fault zones developed from geological and geophysical data provides the hydrostructural backbone controlling the most intense fracturing and dynamic conduits for fluids. Models of ductile deformation and lithology form a tectonic framework for the description of fracture heterogeneity in the background rock, revealing correlations between the intensity and orientation of fractures with geological and spatial properties. The sizes of brittle features are found to be best defined on two scales relating to individual fractures and zones. Inferred fracture-specific from flow logging are correlated with fracture geometric and mechanical properties along with in situ stress measurements to create a hydromechanical description of fracture hydraulic properties. The insights and understandings gained from these efforts help define a discrete fracture network (DFN) model for the Olkiluoto site, with hydrogeological characteristics consistent with monitoring data of hydraulic heads and their disturbances to pumping and underground construction. This work offers ideas and proposed solutions on how some of the challenges in describing fractured rock hydrogeology can be tackled.

Radionuclide Imaging of Musculoskeletal Injuries in Athletes with Negative Radiographs.

PubMed

Nagle, C E; Freitas, J E

1987-06-01

In brief: Radionuclide bone scans can be useful in the diagnostic evaluation of musculoskeletal injuries in athletes. Bone scans can detect shinsplints, stress fractures, and muscle injuries before they are detectable on radiographs. Prognosis can be accurately assessed, allowing appropriate treatment to proceed without delay. The authors discuss the use of bone scans and identify musculoskeletal injuries that are associated with specific sports, such as stress fracture of the femur (soccer), tibia (running), scapula (gymnastics), and pars interarticularis (football or lacrosse).

Detection of Bone Marrow Edema in Nondisplaced Hip Fractures: Utility of a Virtual Noncalcium Dual-Energy CT Application.

PubMed

Kellock, Trenton T; Nicolaou, Savvas; Kim, Sandra S Y; Al-Busaidi, Sultan; Louis, Luck J; O'Connell, Tim W; Ouellette, Hugue A; McLaughlin, Patrick D

2017-09-01

Purpose To quantify the sensitivity and specificity of dual-energy computed tomographic (CT) virtual noncalcium images in the detection of nondisplaced hip fractures and to assess whether obtaining these images as a complement to bone reconstructions alters sensitivity, specificity, or diagnostic confidence. Materials and Methods The clinical research ethics board approved chart review, and the requirement to obtain informed consent was waived. The authors retrospectively identified 118 patients who presented to a level 1 trauma center emergency department and who underwent dual-energy CT for suspicion of a nondisplaced traumatic hip fracture. Clinical follow-up was the standard of reference. Three radiologists interpreted virtual noncalcium images for traumatic bone marrow edema. Bone reconstructions for the same cases were interpreted alone and then with virtual noncalcium images. Diagnostic confidence was rated on a scale of 1 to 10. McNemar, Fleiss κ, and Wilcoxon signed-rank tests were used for statistical analysis. Results Twenty-two patients had nondisplaced hip fractures and 96 did not have hip fractures. Sensitivity with virtual noncalcium images was 77% and 91% (17 and 20 of 22 patients), and specificity was 92%-99% (89-95 of 96 patients). Sensitivity increased by 4%-5% over that with bone reconstruction images alone for two of the three readers when both bone reconstruction and virtual noncalcium images were used. Specificity remained unchanged (99% and 100%). Diagnostic confidence in the exclusion of fracture was improved with combined bone reconstruction and virtual noncalcium images (median score: 10, 9, and 10 for readers 1, 2, and 3, respectively) compared with bone reconstruction images alone (median score: 9, 8, and 9). Conclusion When used as a supplement to standard bone reconstructions, dual-energy CT virtual noncalcium images increased sensitivity for the detection of nondisplaced traumatic hip fractures and improved diagnostic confidence in the exclusion of these fractures. © RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on March 17, 2017.

Characterization of Preferential Flow Path in Fractured Rock Using Heat-pulse Flowmeter

NASA Astrophysics Data System (ADS)

Lee, Tsai-Ping; Lin, Ming-Hsuan; Chuang, Po-Yu; Chia, Yeeping

2015-04-01

Rigorous thinking on how to dispose radioactive wastes safely is essential to mankind and living environment. The concepts of multiple barriers and deep geologic disposal remain the preferred option to retard the radionuclide migration in most countries. However, the investigation of preferential groundwater flow path in a fractured rock is a challenge to the characterization of potential disposal site. Heat-pulse flowmeter is a developing logging tool for measuring the vertical flow velocity in a borehole under a constant pumping or injection rate and provides a promising direct measurement method for determining the vertical distribution of hydraulic conductivity of formation. As heat-pulse flowmeter is a potential technique to measure low-velocity borehole flow, we adopted it to test the feasibility of detecting permeable fractures. Besides, a new magnetic tracer made by nano-iron particles is developed to identify the possible flow path precisely and to verify the permeable section detected by the heat-pulse flowmeter. The magnetic tracer was received by a magnet array and can also be detected by a sensor of electric conductivity. The test site is located in the Heshe of Taiwan. Eight wells were established in a fractured sandy siltstone for characterizing the fracture network. The test wells are 25 to 45 m depth and opened ranging from 15 to 45 m. Prior to the heat-pulse flowmeter measurement, we also performed surface geological investigation, pumping test, geophysical logging, and salt tracer test. Field measurements using heat-pulse flowmeter were then conducted at a constant pumping rate. The measurement interval is 50 to 100 cm in depth but improved to 25 cm near the relatively permeable zone. Based on the results of heat-pulse flowmeter, several permeable sections were identified. The magnetic tracer tests were then conducted to verify the potential preferential flow pathway between adjacent wells. Test results indicated that water flow in borehole is produced primarily from a few fractures. However, the large aperture and high density of fractures did not certainly correlate well to the permeable section. Integration of heat-pulse flowmeter measurement with other in-situ tests, it is possible to identify the exact location of the highly permeable fractures.

Ankle syndesmotic injury.

PubMed

Zalavras, Charalampos; Thordarson, David

2007-06-01

Ankle syndesmotic injury does not necessarily lead to ankle instability; however, the coexistence of deltoid ligament injury critically destabilizes the ankle joint. Syndesmotic injury may occur in isolation or may be associated with ankle fracture. In the absence of fracture, physical examination findings suggestive of injury include ankle tenderness over the anterior aspect of the syndesmosis and a positive squeeze or external rotation test. Radiographic findings usually include increased tibiofibular clear space decreased tibiofibular overlap, and increased medial clear space. However, syndesmotic injury may not be apparent radiographically; thus, routine stress testing is necessary for detecting syndesmotic instability. The goals of management are to restore and maintain the normal tibiofibular relationship to allow for healing of the ligamentous structures of the syndesmosis. Fixation of the syndesmosis is indicated when evidence of a diastasis is present. This may be detected preoperatively, in the absence of fracture, or intraoperatively, after rigid fixation of the medial malleolus and fibula fractures. Failure to diagnose and stabilize syndesmotic disruption adversely affects outcome.

Preoperative Radiographic and CT Findings Predicting Syndesmotic Injuries in Supination-External Rotation-Type Ankle Fractures.

PubMed

Choi, Young; Kwon, Soon-Sun; Chung, Chin Youb; Park, Moon Seok; Lee, Seung Yeol; Lee, Kyoung Min

2014-07-16

The Lauge-Hansen classification system does not provide sufficient data related to syndesmotic injuries in supination-external rotation (SER)-type ankle fractures. The aim of the present study was to investigate factors helpful for the preoperative detection of syndesmotic injuries in SER-type ankle fractures using radiographs and computed tomography (CT). A cohort of 191 consecutive patients (104 male and eighty-seven female patients with a mean age [and standard deviation] of 50.7 ± 16.4 years) with SER-type ankle fractures who had undergone operative treatment were included. Preoperative ankle radiographs and CT imaging scans were made for all patients, and clinical data, including age, sex, and mechanism of injury (high or low-energy trauma), were collected. Patients were divided into two groups: the stable syndesmotic group and the unstable syndesmotic group, with a positive intraoperative lateral stress test leading to syndesmotic screw fixation. Fracture height, fracture length, medial joint space, extent of fracture, and bone attenuation were measured on radiographs and CT images and were compared between the groups. Binary logistic regression analysis was performed to identify the factors that significantly contributed to unstable syndesmotic injuries. Receiver operating characteristic curves were calculated, and cutoff values were suggested to predict unstable syndesmotic injuries on preoperative imaging measurements. Of the 191 patents with a SER-type ankle fracture, thirty-eight (19.9%) had a concurrent unstable syndesmotic injury. Age, sex, mechanism of injury, fracture height, medial joint space, and bone attenuation were significantly different between the two groups. In the binary logistic analysis, fracture height, medial joint space, and bone attenuation were found to be significant factors contributing to unstable syndesmotic injuries. The cutoff values for predicting unstable syndesmotic injuries were a fracture height of >3 mm and a medial joint space of >4.9 mm on CT scans, and a fracture height of >7 mm and medial joint space of >4.5 mm on radiographs. Fracture height, medial joint space, and bone attenuation were useful factors for the preoperative detection of unstable syndesmotic injuries in SER-type ankle fractures. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Context of ancient aqueous environments on Mars from in situ geologic mapping at Endeavour Crater

USGS Publications Warehouse

Crumpler, L.S.; Arvidson, R. E.; Bell, J.; Clark, B. C.; Cohen, B. A.; Farrand, W. H.; Gellert, Ralf; Golombek, M.; Grant, J. A.; Guinness, E.; Herkenhoff, Kenneth E.; Johnson, J. R.; Jolliff, B.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T.; Rice, J. W.; Squyres, S. W.; Sullivan, R.; Yen, A. S.

2015-01-01

Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22 km diameter Endeavour Crater (Latitude −2°16′33″, Longitude −5°10′51″). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units predate the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic Formation, represents conditions on early Mars predating the formation of Endeavour Crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-Endeavour rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or hydrothermal fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (>8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.

Application of electrical resistivity tomography techniques for mapping man-made sinkholes

NASA Astrophysics Data System (ADS)

Rey, J.; Martínez, J.; Hidalgo, C.; Dueñas, J.

2012-04-01

The suitability of the geophysical prospecting by electrical resistivity tomography to detect and map man-made subsurface cavities and related sinkholes has been studied in the Linares abandoned mining district (Spain). We have selected for this study four mined sectors constituted of different lithologies: granite and phyllites of Paleozoic age, and Triassic shales and sandstones. In three of these sectors, detail underground topographic surveys were carried out to chart the position and dimensions of the mining voids (galleries and chamber), in order to analyze the resolution of this methodology to characterize these cavities by using different electrode arrays. The results are variable, depending on the depth and diameter of the void, the selected electrode array, the spacing between electrodes, geological complexity and data density. These results also indicate that when the cavity is empty, an anomaly with a steep gradient and high resistivity values is registered, because the air that fills the mining void is dielectric, while when the cavities are filled with fine grain sediments, frequently saturated in water, the electrical resistance is lower. In relation with the three different multi-electrode arrays tested, the Wenner-Schlumberger array has resulted to offer the maximum resolution in all these cases, with lower and more stable values for the RMS than the other arrays. Therefore, this electrode array has been applied in the fourth studied sector, a former mine near the city centre of Linares, in an area of urban expansion in which there are problems of subsidence. Two sets of four electrical tomography profiles have been carried out, perpendicular to each other, and which have allowed reaching depths of research between 30-35 m. This net-array allowed the identification of two shallow anomalies of low resistivity values, interpreted as old mining galleries filled with fine material saturated in water. It also allows detecting two fractures, correlated in the profiles and which can be mapped to more than 25 m in depth. As showed by this case study, electrical resistivity tomography can be a suitable tool in sub-surface cavities detection and man-made sinkhole investigations.

Microscopic Observation of the Side Surface of Dynamically-Tensile-Fractured 6061-T6 and 2219-T87 Aluminum Alloys with Pre-Fatigue

NASA Astrophysics Data System (ADS)

Itabashi, Masaaki; Nakajima, Shigeru; Fukuda, Hiroshi

After unexpected failure of metallic structure, microscopic investigation will be performed. Generally, such an investigation is limited to search striation pattern with a SEM (scanning electron microscope). But, when the cause of the failure was not severe repeated stress, this investigation is ineffective. In this paper, new microscopic observation technique is proposed to detect low cycle fatigue-impact tensile loading history. Al alloys, 6061-T6 and 2219-T87, were fractured in dynamic tension, after severe pre-fatigue. The side surface of the fractured specimens was observed with a SEM. Neighboring fractured surface, many opened cracks on the side surface have been generated. For each specimen, the number of the cracks was counted together with information of individual sizes and geometric features. For 6061-T6 alloy specimen with the pre-fatigue, the number of the cracks is greater than that for the specimen without the pre-fatigue. For 2219-T87 alloy, the same tendency can be found after a certain screening of the crack counting. Therefore, the crack counting technique may be useful to detect the existence of the pre-fatigue from the dynamically fractured specimen surface.

Local nanoscale strain mapping of a metallic glass during in situ testing

NASA Astrophysics Data System (ADS)

Gammer, Christoph; Ophus, Colin; Pekin, Thomas C.; Eckert, Jürgen; Minor, Andrew M.

2018-04-01

The local elastic strains during tensile deformation in a CuZrAlAg metallic glass are obtained by fitting an elliptic shape function to the characteristic amorphous ring in electron diffraction patterns. Scanning nanobeam electron diffraction enables strain mapping with a resolution of a few nanometers. Here, a fast direct electron detector is used to acquire the diffraction patterns at a sufficient speed to map the local transient strain during continuous tensile loading in situ in the transmission electron microscope. The elastic strain in tensile direction was found to increase during loading. After catastrophic fracture, a residual elastic strain that relaxes over time was observed.

Thrust-induced collapse of mountains-an example from the "Big Bend" region of the San Andreas Fault, western transverse ranges, California

USGS Publications Warehouse

Kellogg, Karl S.

2005-01-01

Mount Pinos and Frazier Mountain are two prominent mountains just south of the San Andreas fault in the western Transverse Ranges of southern California, a region that has undergone rapid Quaternary contraction and uplift. Both mountains are underlain, at least in part, by thrusts that place granitic and gneissic rocks over sedimentary rocks as young as Pliocene. Broad profiles and nearly flat summits of each mountain have previously been interpreted as relicts of a raised erosion surface. However, several features bring this interpretation into question. First, lag or stream gravels do not mantle the summit surfaces. Second, extensive landslide deposits, mostly pre?Holocene and deeply incised, mantle the flanks of both mountains. Third, a pervasive fracture and crushed?rock network pervades the crystalline rocks underlying both mountains. The orientation of the fractures, prominent in roadcuts on Mount Pinos, is essentially random. 'Hill?and?saddle' morphology characterizes ridges radiating from the summits, especially on Mount Pinos; outcrops are sparse on the hills and are nonexistent in the saddles, suggesting fractures are concentrated in the saddles. Latest movement on the thrusts underlying the two mountain massifs is probably early Quaternary, during which the mountains were uplifted to considerably higher (although unknown) elevations than at present. A model proposes that during thrusting, ground accelerations in the hanging wall, particularly near thrust tips, were high enough to pervasively fracture the hanging?wall rocks, thereby weakening them and producing essentially an assemblage of loose blocks. Movement over flexures in the fault surface accentuated fracturing. The lowered shear stresses necessary for failure, coupled with deep dissection and ongoing seismic activity, reduced gravitational potential by spreading the mountain massifs, triggering flanking landslides and producing broad, flat?topped mountains. This study developed from mapping in the western Transverse Ranges as part of the U.S. Geological Survey's Southern California Areal Mapping Project (SCAMP).

Fracture prediction using modified mohr coulomb theory for non-linear strain paths using AA3104-H19

NASA Astrophysics Data System (ADS)

Dick, Robert; Yoon, Jeong Whan

2016-08-01

Experiment results from uniaxial tensile tests, bi-axial bulge tests, and disk compression tests for a beverage can AA3104-H19 material are presented. The results from the experimental tests are used to determine material coefficients for both Yld2000 and Yld2004 models. Finite element simulations are developed to study the influence of materials model on the predicted earing profile. It is shown that only the YLD2004 model is capable of accurately predicting the earing profile as the YLD2000 model only predicts 4 ears. Excellent agreement with the experimental data for earing is achieved using the AA3104-H19 material data and the Yld2004 constitutive model. Mechanical tests are also conducted on the AA3104-H19 to generate fracture data under different stress triaxiality conditions. Tensile tests are performed on specimens with a central hole and notched specimens. Torsion of a double bridge specimen is conducted to generate points near pure shear conditions. The Nakajima test is utilized to produce points in bi-axial tension. The data from the experiments is used to develop the fracture locus in the principal strain space. Mapping from principal strain space to stress triaxiality space, principal stress space, and polar effective plastic strain space is accomplished using a generalized mapping technique. Finite element modeling is used to validate the Modified Mohr-Coulomb (MMC) fracture model in the polar space. Models of a hole expansion during cup drawing and a cup draw/reverse redraw/expand forming sequence demonstrate the robustness of the modified PEPS fracture theory for the condition with nonlinear forming paths and accurately predicts the onset of failure. The proposed methods can be widely used for predicting failure for the examples which undergo nonlinear strain path including rigid-packaging and automotive forming.

Gas hydrate reservoirs and gas migration mechanisms in the Terrebonne Basin, Gulf of Mexico

DOE PAGES

Hillman, Jess I. T.; Cook, Ann E.; Daigle, Hugh; ...

2017-07-27

Here, the interactions of microbial methane generation in fine-grained clay-rich sediments, methane migration, and gas hydrate accumulation in coarse-grained, sand-rich sediments are not yet fully understood. The Terrebonne Basin in the northern Gulf of Mexico provides an ideal setting to investigate the migration of methane resulting in the formation of hydrate in thin sand units interbedded with fractured muds. Using 3D seismic and well log data, we have identified several previously unidentified hydrate bearing units in the Terrebonne Basin. Two units are >100 m- thick fine-grained clay-rich units where gas hydrate occurs in near-vertical fractures. In some locations, these fine-grainedmore » units lack fracture features, and they contain 1-4-m thick hydrate bearing-sands. In addition, several other thin sand units were identified that contain gas hydrate, including one sand that was intersected by a well at the location of a discontinuous bottom-simulating reflector. Using correlation of well log data to seismic data, we have mapped and described these new units in detail across the extent of the available data, allowing us to determine the variation of seismic amplitudes and investigate the distribution of free gas and/or hydrate. We present several potential source-reservoir scenarios between the thick fractured mud units and thin hydrate bearing sands. We observe that hydrate preferentially forms within thin sand layers rather than fractures when sands are present in larger marine mud units. Based on regional mapping showing the patchy lateral extent of the thin sand layers, we propose that diffusive methane migration or short-migration of microbially generated methane from the marine mud units led to the formation of hydrate in these thin sands, as discontinuous sands would not be conducive to long-range migration of methane from deeper reservoirs.« less

Gas hydrate reservoirs and gas migration mechanisms in the Terrebonne Basin, Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillman, Jess I. T.; Cook, Ann E.; Daigle, Hugh

Here, the interactions of microbial methane generation in fine-grained clay-rich sediments, methane migration, and gas hydrate accumulation in coarse-grained, sand-rich sediments are not yet fully understood. The Terrebonne Basin in the northern Gulf of Mexico provides an ideal setting to investigate the migration of methane resulting in the formation of hydrate in thin sand units interbedded with fractured muds. Using 3D seismic and well log data, we have identified several previously unidentified hydrate bearing units in the Terrebonne Basin. Two units are >100 m- thick fine-grained clay-rich units where gas hydrate occurs in near-vertical fractures. In some locations, these fine-grainedmore » units lack fracture features, and they contain 1-4-m thick hydrate bearing-sands. In addition, several other thin sand units were identified that contain gas hydrate, including one sand that was intersected by a well at the location of a discontinuous bottom-simulating reflector. Using correlation of well log data to seismic data, we have mapped and described these new units in detail across the extent of the available data, allowing us to determine the variation of seismic amplitudes and investigate the distribution of free gas and/or hydrate. We present several potential source-reservoir scenarios between the thick fractured mud units and thin hydrate bearing sands. We observe that hydrate preferentially forms within thin sand layers rather than fractures when sands are present in larger marine mud units. Based on regional mapping showing the patchy lateral extent of the thin sand layers, we propose that diffusive methane migration or short-migration of microbially generated methane from the marine mud units led to the formation of hydrate in these thin sands, as discontinuous sands would not be conducive to long-range migration of methane from deeper reservoirs.« less

Estimation of Dry Fracture Weakness, Porosity, and Fluid Modulus Using Observable Seismic Reflection Data in a Gas-Bearing Reservoir

NASA Astrophysics Data System (ADS)

Chen, Huaizhen; Zhang, Guangzhi

2017-05-01

Fracture detection and fluid identification are important tasks for a fractured reservoir characterization. Our goal is to demonstrate a direct approach to utilize azimuthal seismic data to estimate fluid bulk modulus, porosity, and dry fracture weaknesses, which decreases the uncertainty of fluid identification. Combining Gassmann's (Vier. der Natur. Gesellschaft Zürich 96:1-23, 1951) equations and linear-slip model, we first establish new simplified expressions of stiffness parameters for a gas-bearing saturated fractured rock with low porosity and small fracture density, and then we derive a novel PP-wave reflection coefficient in terms of dry background rock properties (P-wave and S-wave moduli, and density), fracture (dry fracture weaknesses), porosity, and fluid (fluid bulk modulus). A Bayesian Markov chain Monte Carlo nonlinear inversion method is proposed to estimate fluid bulk modulus, porosity, and fracture weaknesses directly from azimuthal seismic data. The inversion method yields reasonable estimates in the case of synthetic data containing a moderate noise and stable results on real data.

Fluid driven fracture mechanics in highly anisotropic shale: a laboratory study with application to hydraulic fracturing

NASA Astrophysics Data System (ADS)

Gehne, Stephan; Benson, Philip; Koor, Nick; Enfield, Mark

2017-04-01

The finding of considerable volumes of hydrocarbon resources within tight sedimentary rock formations in the UK led to focused attention on the fundamental fracture properties of low permeability rock types and hydraulic fracturing. Despite much research in these fields, there remains a scarcity of available experimental data concerning the fracture mechanics of fluid driven fracturing and the fracture properties of anisotropic, low permeability rock types. In this study, hydraulic fracturing is simulated in a controlled laboratory environment to track fracture nucleation (location) and propagation (velocity) in space and time and assess how environmental factors and rock properties influence the fracture process and the developing fracture network. Here we report data on employing fluid overpressure to generate a permeable network of micro tensile fractures in a highly anisotropic shale ( 50% P-wave velocity anisotropy). Experiments are carried out in a triaxial deformation apparatus using cylindrical samples. The bedding planes are orientated either parallel or normal to the major principal stress direction (σ1). A newly developed technique, using a steel guide arrangement to direct pressurised fluid into a sealed section of an axially drilled conduit, allows the pore fluid to contact the rock directly and to initiate tensile fractures from the pre-defined zone inside the sample. Acoustic Emission location is used to record and map the nucleation and development of the micro-fracture network. Indirect tensile strength measurements at atmospheric pressure show a high tensile strength anisotropy ( 60%) of the shale. Depending on the relative bedding orientation within the stress field, we find that fluid induced fractures in the sample propagate in two of the three principal fracture orientations: Divider and Short-Transverse. The fracture progresses parallel to the bedding plane (Short-Transverse orientation) if the bedding plane is aligned (parallel) with the direction of σ1. Conversely, the crack plane develops perpendicular to the bedding plane, if the bedding plane is orientated normal to σ1. Fracture initiation pressures are higher in the Divider orientation ( 24MPa) than in the Short-Transverse orientation ( 14MPa) showing a tensile strength anisotropy ( 42%) comparable to ambient tensile strength results. We then use X-Ray Computed Tomography (CT) 3D-images to evaluate the evolved fracture network in terms of fracture pattern, aperture and post-test water permeability. For both fracture orientations, very fine, axial fractures evolve over the entire length of the sample. For the fracturing in the Divider orientation, it has been observed, that in some cases, secondary fractures are branching of the main fracture. Test data from fluid driven fracturing experiments suggest that fracture pattern, fracture propagation trajectories and fracturing fluid pressure (initiation and propagation pressure) are predominantly controlled by the interaction between the anisotropic mechanical properties of the shale and the anisotropic stress environment. The orientation of inherent rock anisotropy relative to the principal stress directions seems to be the main control on fracture orientation and required fracturing pressure.

Spatially offset raman spectroscopy for non-invasive assessment of fracture healing

NASA Astrophysics Data System (ADS)

Ding, Hao; Lu, Guijin; West, Christopher; Gogola, Gloria; Kellam, James; Ambrose, Catherine; Bi, Xiaohong

2016-02-01

Fracture non-unions and bone re-fracture are common challenges for post-fracture management. To achieve better prognosis and treatment evaluation, it is important to be able to assess the quality of callus over the time course of healing. This study evaluated the potential of spatially offset Raman spectroscopy for assessing the fracture healing process in situ. We investigated a rat model of fracture healing at two weeks and 4 weeks post fracture with a fractured femur and a contralateral control in each animal. Raman spectra were collected from the depilated thighs on both sides transcutaneously in situ with various source/detection offsets. Bone signals were recovered from SORS spectra, and then compared with those collected from bare bones. The relative intensity of mineral from fractured bone was markedly decreased compared to the control. The fractured bones demonstrated lower mineral and carbonate level and higher collagen content in the callus at the early time point. Compared to week 2, collagen mineralization and mineral carbonation increased at 4 weeks post fracture. Similarly, the material properties of callus determined by reference point indentation also increased in the 4-week group, indicating improved callus quality with time. The results from Raman analysis are in agreement with radiographic and material testing, indicating the potential of this technique in assessing fracture healing in vivo.

Determinants of patronage of traditional bone setters in the middle belt of Nigeria.

PubMed

Nwadiaro, H C; Ozoilo, K N; Nwadiaro, P O; Kidmas, A T; Oboiren, M

2008-01-01

Traditional bone setting is a practice that is common in our environment. This is a community based survey of opinions concerning orthodox and traditional fracture management in four states of the middle belt of Nigeria. We set out to ascertain the factors influencing preference of treatment of fractures among populations in the middle belt of Nigeria. A community based questionnaire survey of randomly selected adults regarding preference of choice of treatment between orthodox and traditional fracture management. One hundred and eighty-six questionnaires were found analyzable with a male to female ratio of 2:1. There was a preponderance of preference for orthodox fracture management (70.4%). Decisions were mainly collegiate, outside the influence of the individual; only 9.9% decided to attend traditional bone setters on their own. Reasons adduced for preference of traditional bone setters were incongruous and inconsistent. A fixated cultural outlook was recognized as being the motivating factor for patronage of traditional bone setters. Need for enlightenment campaign of the public against patronage of traditional bone setters is emphasized. A gradual phasing out of traditional bone setting with a road map towards making orthodox fracture management available to all is advocated.

[Imaging of traumatic injuries of the knee].

PubMed

Blin, D; Cyteval, C; Kamba, C; Blondel, M; Lopez, F M

2007-05-01

Traumatic injuries to the knee are frequent (road or sports related accidents, falls in elderly people). The Ottawa knee rules are applied and dictate the need for additional evaluation. Some fractures are adequately assessed on plain radiographs alone whereas other fractures (tibial plateau fracture) require additional evaluation with CT. Some fractures may be occult: the significance of lipohemarthrosis (indirect sign of intra-articular fracture on the lateral radiograph with horizontal beam) must be known. Benign appearing avulsion fractures suggest the presence of underlying capsuloligamentous injuries requiring further evaluation with MRI. The imaging work-up of sprains is usually negative. MRI may show areas of bone contusion that further the understanding of the mechanism of injury, predict and confirm the presence of capsuloligamentous injuries. Angiography is performed to detect popliteal artery injuries after knee dislocation which is associated with a risk of ischemia.

Numerical modeling of flow and transport in the far-field of a generic nuclear waste repository in fractured crystalline rock using updated fracture continuum model

NASA Astrophysics Data System (ADS)

Hadgu, T.; Kalinina, E.; Klise, K. A.; Wang, Y.

2016-12-01

Disposal of high-level radioactive waste in a deep geological repository in crystalline host rock is one of the potential options for long term isolation. Characterization of the natural barrier system is an important component of the disposal option. In this study we present numerical modeling of flow and transport in fractured crystalline rock using an updated fracture continuum model (FCM). The FCM is a stochastic method that maps the permeability of discrete fractures onto a regular grid. The original method by McKenna and Reeves (2005) has been updated to provide capabilities that enhance representation of fractured rock. As reported in Hadgu et al. (2015) the method was first modified to include fully three-dimensional representations of anisotropic permeability, multiple independent fracture sets, and arbitrary fracture dips and orientations, and spatial correlation. More recently the FCM has been extended to include three different methods. (1) The Sequential Gaussian Simulation (SGSIM) method uses spatial correlation to generate fractures and define their properties for FCM (2) The ELLIPSIM method randomly generates a specified number of ellipses with properties defined by probability distributions. Each ellipse represents a single fracture. (3) Direct conversion of discrete fracture network (DFN) output. Test simulations were conducted to simulate flow and transport using ELLIPSIM and direct conversion of DFN methods. The simulations used a 1 km x 1km x 1km model domain and a structured with grid block of size of 10 m x 10m x 10m, resulting in a total of 106 grid blocks. Distributions of fracture parameters were used to generate a selected number of realizations. For each realization, the different methods were applied to generate representative permeability fields. The PFLOTRAN (Hammond et al., 2014) code was used to simulate flow and transport in the domain. Simulation results and analysis are presented. The results indicate that the FCM approach is a viable method to model fractured crystalline rocks. The FCM is a computationally efficient way to generate realistic representation of complex fracture systems. This approach is of interest for nuclear waste disposal models applied over large domains. SAND2016-7509 A

Post-injection Multiphase Flow Modeling and Risk Assessments for Subsurface CO2 Storage in Naturally Fractured Reservoirs

NASA Astrophysics Data System (ADS)

Jin, G.

2015-12-01

Subsurface storage of carbon dioxide in geological formations is widely regarded as a promising tool for reducing global atmospheric CO2 emissions. Successful geologic storage for sequestrated carbon dioxides must prove to be safe by means of risk assessments including post-injection analysis of injected CO2 plumes. Because fractured reservoirs exhibit a higher degree of heterogeneity, it is imperative to conduct such simulation studies in order to reliably predict the geometric evolution of plumes and risk assessment of post CO2injection. The research has addressed the pressure footprint of CO2 plumes through the development of new techniques which combine discrete fracture network and stochastic continuum modeling of multiphase flow in fractured geologic formations. A subsequent permeability tensor map in 3-D, derived from our preciously developed method, can accurately describe the heterogeneity of fracture reservoirs. A comprehensive workflow integrating the fracture permeability characterization and multiphase flow modeling has been developed to simulate the CO2plume migration and risk assessments. A simulated fractured reservoir model based on high-priority geological carbon sinks in central Alabama has been employed for preliminary study. Discrete fracture networks were generated with an NE-oriented regional fracture set and orthogonal NW-fractures. Fracture permeability characterization revealed high permeability heterogeneity with an order of magnitude of up to three. A multiphase flow model composed of supercritical CO2 and saline water was then applied to predict CO2 plume volume, geometry, pressure footprint, and containment during and post injection. Injection simulation reveals significant permeability anisotropy that favors development of northeast-elongate CO2 plumes, which are aligned with systematic fractures. The diffusive spreading front of the CO2 plume shows strong viscous fingering effects. Post-injection simulation indicates significant upward lateral spreading of CO2 resulting in accumulation of CO2 directly under the seal unit because of its buoyancy and strata-bound vertical fractures. Risk assessment shows that lateral movement of CO2 along interconnected fractures requires widespread seals with high integrity to confine the injected CO2.

Fracture Networks from a deterministic physical model as 'forerunners' of Maze Caves

NASA Astrophysics Data System (ADS)

Ferer, M. V.; Smith, D. H.; Lace, M. J.

2013-12-01

'Fractures are the chief forerunners of caves because they transmit water much more rapidly than intergranular pores.[1] Thus, the cave networks can follow the fracture networks from which the Karst caves formed by a variety of processes. Traditional models of continental Karst define water flow through subsurface geologic formations, slowly dissolving the rock along the pathways (e.g. water saturated with respect to carbon dioxide flowing through fractured carbonate formations). We have developed a deterministic, physical model of fracturing in a model geologic layer of a given thickness, when that layer is strained in one direction and subsequently in a perpendicular direction. It was observed that the connected fracture networks from our model visually resemble maps of maze caves. Since these detailed cave maps offer critical tools in modeling cave development patterns and conduit flow in Karst systems, we were able to test the qualitative resemblance by using statistical analyses to compare our model networks in geologic layers of four different thicknesses with the corresponding statistical analyses of four different maze caves, formed in a variety of geologic settings. The statistical studies performed are: i) standard box-counting to determine if either the caves or the model networks are fractal. We found that both are fractal with a fractal dimension Df ≈ 1.75 . ii) for each section inside a closed path, we determined the area and perimeter-length, enabling a study of the tortuosity of the networks. From the dependence of the section's area upon its perimeter-length, we have found a power-law behavior (for sufficiently large sections) characterized by a 'tortuosity' exponent. These exponents have similar values for both the model networks and the maze caves. The best agreement is between our thickest model layer and the maze-like part of Wind Cave in South Dakota where the data from the model and the cave overlie each other. For the present networks from the physical model, we assumed that the geologic layer was of uniform thickness and that the strain in both directions were the same. The latter may not be the case for the Brazilian, Toca de Boa Cave. These assumptions can be easily modified in our computer code to reflect different geologic histories. Even so the quantitative agreement suggests that our model networks are statistically realistic both for the 'forerunners' of caves and for general fracture networks in geologic layers, which should assist the study of underground fluid flow in many applications for which fracture patterns and fluid flow are difficult to determine (e.g., hydrology, watershed management, oil recovery, carbon dioxide sequestration, etc.). Keywords - Fracture Networks, Karst, Caves, Structurally Variable Pathways, hydrogeological modeling 1 Arthur N. Palmer, CAVE GEOLOGY, pub. Cave Books, Dayton OH, (2007).

Geologic Map of the Diana Chasma Quadrangle (V-37), Venus

USGS Publications Warehouse

Hansen, V.L.; DeShon, H.R.

2002-01-01

Diana Chasma quadrangle hosts some of the steepest topography on Venus. Altimetry measurements range from -2.5 to 4.7 km (0.0 = mean planetary radius), with a surface mean of 0.6 km. Fractures and faults within the central fracture/rift zone create large blocks of down-dropped material, especially along the east-central edge of the map area. The Dali and Diana chasmata display slopes of >30°, the steepest and deepest trenches on Venus. Both chasmata host landslide deposits presumably sourced from the steep chasmata walls. The tessera inlier, coronae, and ridge belts sit topographically above Rusalka and Zhibek planitiae. Rusalka Planitia topography describes broad undulations having northwest-trending ridges spaced ~200 km apart. The most distinctive ridge, Vetsorgo Dorsum, centered at 6.5° S., 163° E., is a Class I ridge belt owing to its simple arch morphology. The central interior of Markham crater sits topographically lower than the surrounding region, which slopes downward to the east.

Structural investigations in the Massif-Central, France

NASA Technical Reports Server (NTRS)

Scanvic, J. Y.

1974-01-01

This survey covered the French Massif-Central (where crystalline and volcanic rocks outcrop) and its surrounding sedimentaries, Bassin de Paris, Bassin d'Aquitaine and Rhodanian valley. One objective was the mapping of fracturing and the surveying of its relationship with known ore deposits. During this survey it was found that ERTS imagery outlines lithology in some sedimentary basins. On the other hand, in a basement area, under temperature climate conditions, lithology is rarely expressed. These observations can be related to the fact that band 5 gives excellent results above sedimentary basins in France and generally band 7 is the most useful in a basement area. Several examples show clearly the value of ERTS imagery for mapping linear features and circular structures. All the main fractures are identified with the exception of new ones found both in sedimentaries and basement areas. Other interesting findings concern sun elevation which, stereoscopic effect not being possible, simulates relief in a better way under certain conditions.

Genetics of osteoporosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urano, Tomohiko; Inoue, Satoshi, E-mail: INOUE-GER@h.u-tokyo.ac.jp; Department of Anti-Aging Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655

Highlights: • Single-nucleotide polymorphisms (SNPs) associated with osteoporosis were identified. • SNPs mapped close to or within VDR and ESR1 are associated with bone mineral density. • WNT signaling pathway plays a pivotal role in regulating bone mineral density. • Genetic studies will be useful for identification of new therapeutic targets. - Abstract: Osteoporosis is a skeletal disease characterized by low bone mineral density (BMD) and microarchitectural deterioration of bone tissue, which increases susceptibility to fractures. BMD is a complex quantitative trait with normal distribution and seems to be genetically controlled (in 50–90% of the cases), according to studies onmore » twins and families. Over the last 20 years, candidate gene approach and genome-wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) that are associated with low BMD, osteoporosis, and osteoporotic fractures. These SNPs have been mapped close to or within genes including those encoding nuclear receptors and WNT-β-catenin signaling proteins. Understanding the genetics of osteoporosis will help identify novel candidates for diagnostic and therapeutic targets.« less

Development of an Advanced Hydraulic Fracture Mapping System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norm Warpinski; Steve Wolhart; Larry Griffin

The project to develop an advanced hydraulic fracture mapping system consisted of both hardware and analysis components in an effort to build, field, and analyze combined data from tiltmeter and microseismic arrays. The hardware sections of the project included: (1) the building of new tiltmeter housings with feedthroughs for use in conjunction with a microseismic array, (2) the development of a means to use separate telemetry systems for the tilt and microseismic arrays, and (3) the selection and fabrication of an accelerometer sensor system to improve signal-to-noise ratios. The analysis sections of the project included a joint inversion for analysismore » and interpretation of combined tiltmeter and microseismic data and improved methods for extracting slippage planes and other reservoir information from the microseisms. In addition, testing was performed at various steps in the process to assess the data quality and problems/issues that arose during various parts of the project. A prototype array was successfully tested and a full array is now being fabricated for industrial use.« less

Implementation of the Ottawa Ankle Rules by nurses working in an accident and emergency department.

PubMed Central

Salt, P; Clancy, M

1997-01-01

OBJECTIVE: To assess whether accident and emergency (A&E) nurses using the Ottawa Ankle Rules could detect all ankle fractures. DESIGN: Prospective observational study. SETTING: A&E department of a university teaching hospital. SUBJECTS: All patients who presented with ankle injuries who were initially assessed by a nurse taught the Ottawa Ankle Rules. OUTCOME MEASURES: (1) The numbers of patients referred by the nurse for ankle radiography; (2) of these, the number with ankle fractures; (3) of those not sent for radiography initially by the nurse, the number who subsequently had x rays (ordered by the doctor) and had a fracture; (4) of those having no x rays, the number who reattended later. RESULTS: 324 patients were eligible; 238 had x rays at the request of the nurse (73%); 48 of these (20%) were diagnosed as having a fracture. Of those 86 patients not sent for radiography by the nurse, 19 subsequently had x ray examinations at the request of a doctor and no fracture was detected. Of the 67 not sent for radiography, none returned within the subsequent eight weeks. CONCLUSIONS: Nurses can apply the Ottawa Ankle Rules safely without missing acute fractures; that is, of those who were not sent for radiography by nurses, none subsequently reattended the A&E department or the trauma service of the Bristol Royal Infirmary during the following two months. PMID:9413774

Detecting dynamic causal inference in nonlinear two-phase fracture flow

NASA Astrophysics Data System (ADS)

Faybishenko, Boris

2017-08-01

Identifying dynamic causal inference involved in flow and transport processes in complex fractured-porous media is generally a challenging task, because nonlinear and chaotic variables may be positively coupled or correlated for some periods of time, but can then become spontaneously decoupled or non-correlated. In his 2002 paper (Faybishenko, 2002), the author performed a nonlinear dynamical and chaotic analysis of time-series data obtained from the fracture flow experiment conducted by Persoff and Pruess (1995), and, based on the visual examination of time series data, hypothesized that the observed pressure oscillations at both inlet and outlet edges of the fracture result from a superposition of both forward and return waves of pressure propagation through the fracture. In the current paper, the author explores an application of a combination of methods for detecting nonlinear chaotic dynamics behavior along with the multivariate Granger Causality (G-causality) time series test. Based on the G-causality test, the author infers that his hypothesis is correct, and presents a causation loop diagram of the spatial-temporal distribution of gas, liquid, and capillary pressures measured at the inlet and outlet of the fracture. The causal modeling approach can be used for the analysis of other hydrological processes, for example, infiltration and pumping tests in heterogeneous subsurface media, and climatic processes, for example, to find correlations between various meteorological parameters, such as temperature, solar radiation, barometric pressure, etc.

An integrated approach to characterization of fractured reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datta-Gupta, A.; Majer, E.; Vasco, D.

1995-12-31

This paper summarizes an integrated hydrologic and seismic characterization of a fractured limestone formation at the Conoco Borehole Test Facility (CBTF) in Kay County, Oklahoma. Transient response from pressure interference tests were first inverted in order to identify location and orientation of dominant fractures at the CBTF. Subsequently, high resolution (1000 to 10000 Hz) cross-well and single-well seismic surveys were conducted to verify the preferential slow paths indicated by hydrologic analysis. Seismic surveys were conducted before and after an air injection in order to increase the visibility of the fracture zone to seismic imaging. Both Seismic and hydrologic analysis weremore » found to yield consistent results in detecting the location of a major fracture zone.« less

The metallogenic role of east-west fracture zones in South America with regard to the motion of lithospheric plates (with an example from Brazil)

USGS Publications Warehouse

Kutina, J.; Carter, William D.; Lopez, F.X.

1978-01-01

The role of east-west fracture zones in South America is discussed with regard to global fracturing and the motion of lithospheric plates. A set of major NW-trending lineaments has been derived which show a tendency to be spaced equidistantly and may correspond to a set of east-west fractures in the "pre-drift" position of the South American plate. Statistical analysis of linears in the ERTS-mosaics shows that NW-fractures are also among the most important ones in the Andes region, suggesting that the above major lineaments extend into the basement of the Andes. Some of the old major fractures, trending east-west in the present orientation of South America, are discussed and their NE orientation in the pre-drift position of the plate is considered. An example of structural control of ore deposition in the Brazilian Shield is presented, using the maps of the RADAM Project. It is concluded that the small tin-bearing granitic bodies concentrated in the region of Sao Felix do Xingu in the state of Para represent upper parts of an unexposed granitoid massif which is controlled by the intersection of a major east-west fracture zone probably represents westward extension of the Patos Lineament of the easternmost part of Brazil, connected with the east-west fracture zone of the Para state through the basement of the Maranhao Basin (Sineclise do Maranhao-Piaui). It is expected that the proposed "Patos-Para Lineament" extends further westward and may similarly control, at intersections with fractures of other trends, some mineralization centers in the western part of the state of Para and in the state of Amazonas.

Are Geotehrmal Reservoirs Stressed Out?

NASA Astrophysics Data System (ADS)

Davatzes, N. C.; Laboso, R. C.; Layland-Bachmann, C. E.; Feigl, K. L.; Foxall, W.; Tabrez, A. R.; Mellors, R. J.; Templeton, D. C.; Akerley, J.

2017-12-01

Crustal permeability can be strongly influenced by developing connected networks of open fractures. However, the detailed evolution of a fracture network, its extent, and the persistence of fracture porosity are difficult to analyze. Even in fault-hosted geothermal systems, where heat is brought to the surface from depth along a fault, hydrothermal flow is heterogeneously distributed. This is presumably due to variations in fracture density, connectivity, and attitude, as well as variations in fracture permeability caused by sealing of fractures by precipitated cements or compaction. At the Brady Geothermal field in Nevada, we test the relationship between the modeled local stress state perturbed by dislocations representing fault slip or volume changes in the geothermal reservoir inferred from surface deformation measured by InSAR and the location of successful geothermal wells, hydrothermal activity, and seismicity. We postulate that permeability is favored in volumes that experience positive Coulomb stress changes and reduced compression, which together promote high densities of dilatant fractures. Conversely, permeability can be inhibited in locations where Coulomb stress is reduced, compression promotes compaction, or where the faults are poorly oriented in the stress field and consequently slip infrequently. Over geologic time scales spanning the development of the fault system, these local stress states are strongly influenced by the geometry of the fault network relative to the remote stress driving slip. At shorter time scales, changes in fluid pressure within the fracture network constituting the reservoir cause elastic dilations and contractions. We integrate: (1) direct observations of stress state and fractures in boreholes and the mapped geometry of the fault network; (2) evidence of permeability from surface hydrothermal features, production/injection wells and surface deformations related to pumping history; and (3) seismicity to test the correlation between the reservoir geometry and models of the local stress state.

Correlation of Hip Fracture with Other Fracture Types: Toward a Rational Composite Hip Fracture Endpoint

PubMed Central

Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.

2016-01-01

Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123

The influence of joint parameters on normal fault evolution and geometry: a parameter study using analogue modeling

NASA Astrophysics Data System (ADS)

Kettermann, Michael; von Hagke, Christoph; Urai, Janos L.

2017-04-01

Dilatant faults often form in rocks containing pre-existing joints, but the effects of joints on fault segment linkage and fracture connectivity is not well understood. Studying evolution of dilatancy and influence of fractures on fault development provides insights into geometry of fault zones in brittle rocks and will eventually allow for predicting their subsurface appearance. In an earlier study we recognized the effect of different angles between strike direction of vertical joints and a basement fault on the geometry of a developing fault zone. We now systematically extend the results by varying geometric joint parameters such as joint spacing and vertical extent of the joints and measuring fracture density and connectivity. A reproducibility study shows a small error-range for the measurements, allowing for a confident use of the experimental setup. Analogue models were carried out in a manually driven deformation box (30x28x20 cm) with a 60° dipping pre-defined basement fault and 4.5 cm of displacement. To produce open joints prior to faulting, sheets of paper were mounted in the box to a depth of 5 cm at a spacing of 2.5 cm. We varied the vertical extent of the joints from 5 to 50 mm. Powder was then sieved into the box, embedding the paper almost entirely (column height of 19 cm), and the paper was removed. During deformation we captured structural information by time-lapse photography that allows particle imaging velocimetry analyses (PIV) to detect localized deformation at every increment of displacement. Post-mortem photogrammetry preserves the final 3-dimensional structure of the fault zone. A counterintuitive result is that joint depth is of only minor importance for the evolution of the fault zone. Even very shallow joints form weak areas at which the fault starts to form and propagate. More important is joint spacing. Very large joint spacing leads to faults and secondary fractures that form subparallel to the basement fault. In contrast, small joint spacing results in fault strands that only localize at the pre-existing joints, and secondary fractures that are oriented at high angles to the pre-existing joints. With this new set of experiments we can now quantitatively constrain how (i) the angle between joints and basement fault, (ii) the joint depth and (iii) the joint spacing affect fault zone parameters such as (1) the damage zone width, (2) the density of secondary fractures, (3) map-view area of open gaps or (4) the fracture connectivity. We apply these results to predict subsurface geometries of joint-fault networks in cohesive rocks, e.g. basaltic sequences in Iceland and sandstones in the Canyonlands NP, USA.

Hydromechanical modeling of clay rock including fracture damage

NASA Astrophysics Data System (ADS)

Asahina, D.; Houseworth, J. E.; Birkholzer, J. T.

2012-12-01

Argillaceous rock typically acts as a flow barrier, but under certain conditions significant and potentially conductive fractures may be present. Fracture formation is well-known to occur in the vicinity of underground excavations in a region known as the excavation disturbed zone. Such problems are of particular importance for low-permeability, mechanically weak rock such as clays and shales because fractures can be relatively transient as a result of fracture self-sealing processes. Perhaps not as well appreciated is the fact that natural fractures can form in argillaceous rock as a result of hydraulic overpressure caused by phenomena such as disequlibrium compaction, changes in tectonic stress, and mineral dehydration. Overpressure conditions can cause hydraulic fracturing if the fluid pressure leads to tensile effective stresses that exceed the tensile strength of the material. Quantitative modeling of this type of process requires coupling between hydrogeologic processes and geomechanical processes including fracture initiation and propagation. Here we present a computational method for three-dimensional, hydromechanical coupled processes including fracture damage. Fractures are represented as discrete features in a fracture network that interact with a porous rock matrix. Fracture configurations are mapped onto an unstructured, three-dimensonal, Voronoi grid, which is based on a random set of spatial points. Discrete fracture networks (DFN) are represented by the connections of the edges of a Voronoi cells. This methodology has the advantage that fractures can be more easily introduced in response to coupled hydro-mechanical processes and generally eliminates several potential issues associated with the geometry of DFN and numerical gridding. A geomechanical and fracture-damage model is developed here using the Rigid-Body-Spring-Network (RBSN) numerical method. The hydrogelogic and geomechanical models share the same geometrical information from a 3D Voronoi grid and associated nodes, where the scalar field quantities (e.g. temperature, pressure, and saturation) and the generalized displacements are obtained by an integral finite difference method (e.g., TOUGH2) and RBSN, respectively. Fractures propagate along Voronoi cell boundaries as induced stresses evolve and exceed the material strength. Examples of fracture propagation in clay rock are examined for the excavation disturbed zone and for cases in which hydraulic overpressure leads to hydraulic fracture. Fluid flow behavior in these evolving fracture networks and eventual fracture closing and self-sealing are investigated. Funding for this work was provided by the Used Fuel Disposition Campaign, Office of Nuclear Energy, of the U.S. Department of Energy under Contract NumberDE-AC02-05CH11231 with Berkeley Lab.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling

NASA Astrophysics Data System (ADS)

Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

2014-12-01

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18 years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27 m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: depth- and strata-dependent spatial variability from rock-core sampling

USGS Publications Warehouse

Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

2014-01-01

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18 years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27 m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

Morphological and structural changes at the Merapi lava dome monitored in 2012-15 using unmanned aerial vehicles (UAVs)

NASA Astrophysics Data System (ADS)

Darmawan, Herlan; Walter, Thomas R.; Brotopuspito, Kirbani Sri; Subandriyo; I Gusti Made Agung Nandaka

2018-01-01

Dome-building volcanoes undergo rapid and profound topographic changes that are important to quantify for the purposes of hazard assessment. However, as hazardous lava domes often develop on high-altitude volcanoes that exhibit steep-sided topography, it is challenging to obtain direct field access and thus to analyze these morphological and structural changes. Merapi Volcano in Indonesia is a type example of such a volcano, as soon after its 2010 eruption, a new lava dome developed. This dome was partially destroyed during six distinct steam-driven explosions that occurred between 2012 and 2014. Here, we investigate the topographic and structural changes associated with these six steam-driven explosions by comparing close-range photogrammetric data obtained before and after these explosions. To accomplish this, we performed two UAV campaigns in 2012 and 2015. By applying the Structure from Motion (SfM) technique, we are able to construct three-dimensional point clouds, assess their quality by comparing them to a terrestrial laser scanning (TLS) dataset, and generate high-resolution Digital Elevation Models (DEMs) and photomosaics. The comparison of these two DEMs and photomosaics reveals changes in topography and the appearance of fractures. In the 2012 dataset, we find a dense fracture network striking to the NNW-SSE. In the post-eruptive 2015 dataset, we see that this NNW-SSE fracture trend is much more strongly expressed; we also detect the formation of aligned and elongated explosion craters, which are associated with the removal of over 200,000 m3 of dome material, most of which ( 70%) was deposited outside the crater region. Therefore, this study suggests that the locations of the steam-driven explosions at Merapi Volcano were controlled by the reactivation of preexisting structures. Moreover, some of the newly developed and reactivated fractures delineate a block on the southern slope of the dome, which could become structurally unstable and potentially lead to rock avalanche hazards. This study therefore demonstrates the significance of characterizing structural fingerprints during the development of lava domes and exemplifies the value of topographic and fracture mapping, which is becoming increasingly feasible when using UAVs, even on high and steep stratovolcanoes. Fig. S2. The density of TLS point cloud dataset.

Integrated detection of fractures and caves in carbonate fractured-vuggy reservoirs based on seismic data and well data

NASA Astrophysics Data System (ADS)

Cao, Zhanning; Li, Xiangyang; Sun, Shaohan; Liu, Qun; Deng, Guangxiao

2018-04-01

Aiming at the prediction of carbonate fractured-vuggy reservoirs, we put forward an integrated approach based on seismic and well data. We divide a carbonate fracture-cave system into four scales for study: micro-scale fracture, meso-scale fracture, macro-scale fracture and cave. Firstly, we analyze anisotropic attributes of prestack azimuth gathers based on multi-scale rock physics forward modeling. We select the frequency attenuation gradient attribute to calculate azimuth anisotropy intensity, and we constrain the result with Formation MicroScanner image data and trial production data to predict the distribution of both micro-scale and meso-scale fracture sets. Then, poststack seismic attributes, variance, curvature and ant algorithms are used to predict the distribution of macro-scale fractures. We also constrain the results with trial production data for accuracy. Next, the distribution of caves is predicted by the amplitude corresponding to the instantaneous peak frequency of the seismic imaging data. Finally, the meso-scale fracture sets, macro-scale fractures and caves are combined to obtain an integrated result. This integrated approach is applied to a real field in Tarim Basin in western China for the prediction of fracture-cave reservoirs. The results indicate that this approach can well explain the spatial distribution of carbonate reservoirs. It can solve the problem of non-uniqueness and improve fracture prediction accuracy.

kISMET: Stress analysis and intermediate-scale hydraulic fracturing at the Sanford Underground Research Facility

NASA Astrophysics Data System (ADS)

Dobson, P. F.; Oldenburg, C. M.; Wu, Y.; Cook, P. J.; Kneafsey, T. J.; Nakagawa, S.; Ulrich, C.; Siler, D. L.; Guglielmi, Y.; Ajo Franklin, J. B.; Rutqvist, J.; Daley, T. M.; Birkholzer, J. T.; Wang, H. F.; Lord, N.; Haimson, B. C.; Sone, H.; Vigilante, P.; Roggenthen, W.; Doe, T.; Lee, M.; Ingraham, M. D.; Huang, H.; Mattson, E.; Johnson, T. C.; Zhou, J.; Zoback, M. D.; Morris, J.; White, J. A.; Johnson, P. A.; Coblentz, D. D.; Heise, J.

2017-12-01

In 2015, we established a field test facility at the Sanford Underground Research Facility (SURF), and in 2016 we carried out in situ hydraulic fracturing experiments to characterize the stress field, understand the effects of crystalline rock fabric on fracturing, and gain experience in monitoring using geophysical methods. The kISMET (permeability (k) and Induced Seismicity Management for Energy Technologies) project test site was established in the West Access Drift at the 4850 ft level, 1478 m below ground in phyllite of the Precambrian Poorman Formation. The kISMET team drilled and cored five near-vertical boreholes in a line on 3 m spacing, deviating the two outermost boreholes slightly to create a five-spot pattern around the test borehole centered in the test volume 40 m below the drift invert (floor) at a total depth of 1518 m. Laboratory measurements of core from the center test borehole showed P-wave velocity heterogeneity along each core indicating strong, fine-scale ( 1 cm or smaller) changes in the mechanical properties of the rock. Tensile strength ranges between 3‒7.5 MPa and 5‒12 MPa. Pre-fracturing numerical simulations with a discrete element code were carried out to predict fracture size and magnitude of microseismicity. Field measurements of the stress field were made using hydraulic fracturing, which produced remarkably uniformly oriented fractures suggesting rock fabric did not play a significant role in controlling fracture orientation. Electrical resistivity tomography (ERT) and continuous active seismic source monitoring (CASSM) were deployed in the four monitoring boreholes, and passive seismic accelerometer-based measurements in the West Access Drift were carried out during the generation of a larger fracture (so-called stimulation test). ERT was not able to detect the fracture created, nor did the accelerometers in the drift, but microseismicity was detected for the first (deepest) hydraulic-fracturing stress measurement. Analytical solutions suggest that the fracture radius of the large fracture (stimulation test) was more than 6 m, depending on the unknown amount of leak-off. Currently kISMET team members are analyzing a large number of borehole breakouts recorded in nearby boreholes at SURF to generate a more complete picture of the stress field and its variations at SURF.

Root bark of Sambucus Williamsii Hance promotes rat femoral fracture healing by the BMP-2/Runx2 signaling pathway.

PubMed

Yang, Bingyou; Lin, Xiaoying; Tan, Jinyan; She, Xian; Liu, Yan; Kuang, Haixue

2016-09-15

Sambucus Williamsii Hance (SWH) is a plant from a family of Caprifoliaceae, which has a long medical history of use as an effective folk treatment for fracture bruises. To evaluate the effects of 50% ethanol extracts of root-bark of Sambucus Williamsii Hance(EE-rbSWH) on fracture healing of rats and explore its mechanism of actions related to the BMP-2 signaling pathway. EE-rbSWH was orally administered at the doses of 340 and 680mg/kg to adult Sprague-Dawley rats with operation of open femur fracture completely for 2, 4 and 8 weeks. And the rats of sham operation and Model groups were administered Vehicle (distilled water 0.8mL/200g/day). Firstly, the bone X-ray morphology and bone mineral density(BMD) of the fracture site were observed and measured after anesthesia the rats at weeks 2, 4, and 8 after surgery, then the serum levels of alkaline phosphatase(ALP) and osteocalcin (BGP) were measured; Secondly, the tissue morphology of the fracture site was observed after sacrificed the rats; Thirdly, the formation of mineralized nodules in bone marrow stromal cells(BMSC) were evaluated at week 2; Lastly, the genes levels of BMP-2 and Runx2 in the femur were detected at week 2 and 4, and the proteins expression of BMP-2 signaling pathway (BMP-2, BMPRIB, BMPRII and Runx2) in the femur also were detected at week 2. EE-rbSWH remarkably accelerated fracture healing by promoting bone formation at all the time points of fracture healing. Mainly by increasing the BMD level at the fracture site, the levels of serum ALP and BGP, and also the numbers increasing of calcified nodules in BMSC. The mechanism studies, EE-rbSWH can promote fracture healing by enhancing the expressions of BMP-2 and Runx2 mRNA, and also the proteins of BMP-2, BMPRIB, BMPRII and Runx2 at the fracture site of rats. Our results suggested that 50% ethanol extracts of root-bark of Sambucus Williamsii Hance can accelerate fracture healing by recruitment of osteoblasts at the fracture site and through up-regulation of the BMP-2 signaling pathway. Copyright © 2016. Published by Elsevier Ireland Ltd.

Dynamic deformation and fracture of single crystal silicon: Fracture modes, damage laws, and anisotropy

DOE PAGES

Huang, J. Y.; E, J. C.; Huang, J. W.; ...

2016-05-25

Impact fracture of single-crystal Si is critical to long-term reliability of electronic devices and solar cells for its wide use as components or substrates in semiconductor industry. Single-crystal Si is loaded along two different crystallographic directions with a split Hopkinson pressure bar integrated with an in situ x-ray imaging and diffraction system. Bulk stress histories are measured, simultaneously with x-ray phase contrast imaging (XPCI) and Laue diffraction. Damage evolution is quantified with grayscale maps from XPCI. Single-crystal Si exhibits pronounced anisotropy in fracture modes, and thus fracture strengths and damage evolution. For loading along [11¯ 0] and viewing along [001],more » (1¯1¯0)[11¯ 0] cleavage is activated and induces horizontal primary cracks followed by perpendicular wing cracks. However, for loading along [011¯] and viewing along [111], random nucleation and growth of shear and tensile-splitting crack networks lead to catastrophic failure of materials with no cleavage. The primary-wing crack mode leads to a lower characteristic fracture strength due to predamage, but a more concentrated strength distribution, i.e., a higher Weibull modulus, compared to the second loading case. Furthermore, the sequential primary cracking, wing cracking and wing-crack coalescence processes result in a gradual increase of damage with time, deviating from theoretical predictions. Particle size and aspect ratios of fragments are discussed with postmortem fragment analysis, which verifies fracture modes observed in XPCI.« less

Borehole-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut

USGS Publications Warehouse

Johnson, Carole D.; Haeni, F.P.; Lane, John W.; White, Eric A.

2002-01-01

A borehole-geophysical investigation was conducted to help characterize the hydrogeology of the fractured-rock aquifer and the distribution of unconsolidated glacial deposits near the former landfill and chemical waste-disposal pits at the University of Connecticut in Storrs, Connecticut. Eight bedrock boreholes near the landfill and three abandoned domestic wells located nearby were logged using conventional and advanced borehole-geophysical methods from June to October 1999. The conventional geophysical-logging methods included caliper, gamma, fluid temperature, fluid resistivity, and electromagnetic induction. The advanced methods included deviation, optical and acoustic imaging of the borehole wall, heat-pulse flowmeter, and directional radar reflection. Twenty-one shallow piezometers (less than 50-feet deep) were logged with gamma and electromagnetic induction tools to delineate unconsolidated glacial deposits. Five additional shallow bedrock wells were logged with conventional video camera, caliper, electromagnetic induction, and fluid resistivity and temperature tools. The rock type, foliation, and fracturing of the site were characterized from high-resolution optical-televiewer (OTV) images of rocks penetrated by the boreholes. The rocks are interpreted as fine- to medium-grained quartz-feldspar-biotite-garnet gneiss and schist with local intrusions of quartz diorite and pegmatite and minor concentrations of sulfide mineralization similar to rocks described as the Bigelow Brook Formation on regional geologic maps. Layers containing high concentrations of sulfide minerals appear as high electrical conductivity zones on electromagnetic-induction and borehole-radar logs. Foliation in the rocks generally strikes to the northeast-southwest and dips to the west, consistent with local outcrop observations. The orientation of foliation and small-scale gneissic layering in the rocks, however, varies locally and with depth in some of the boreholes. In two of the boreholes, the foliation strikes predominantly to the northwest and dips to the northeast. Although small-scale faults and lithologic discontinuities were observed in the OTV data, no large-scale faults were observed that appear on regional geologic maps. Fractures were located and characterized through the use of conventional geophysical, OTV, acoustic-televiewer (ATV), and borehole-radar logs. The orientation of fractures varies considerably across the site; some fractures are parallel to the foliation, whereas others cross-cut the foliation. Many of the transmissive fractures in the bedrock boreholes strike about N170?E and N320?E with dips of less than 45?. Other transmissive fractures strike about N60?E with dips of more than 60?. Most of the transmissive fractures in the domestic wells strike about N60?E and N22?E with dips of more than 45?. The strike of N60?E is parallel to the trend of a thrust fault that appears on regional geologic maps. Vertical flow in the boreholes was measured with the heat-pulse flowmeter under ambient and (or) pumping conditions. Results of ATV, OTV, and conventional logs were used to locate specific zones for flowmeter testing. Ambient downflow was measured in three boreholes, ambient upflow was measured in two other boreholes, and both ambient downflow and upflow were measured in a sixth borehole. The other five bedrock boreholes and domestic wells did not have measurable vertical flow. The highest rate of ambient flow was measured in the background borehole in which upflow and downflow converged and exited the borehole at a fracture zone near a depth of 62 feet. Ambient flow of about 340 gallons per day was measured. In the other five wells, ambient flow of about 20 to 35 gallons per day was measured. Under low-rate pumping (0.25 to 1 gallon per minute), one to six inflow zones were identified in each well. Usually the fractures that are active under ambient conditions contribute to the well under pumping conditions. To prevent

Evaluation of Oil-Industry Stimulation Practices for Engineered Geothermal Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Van Dyke; Leen Weijers; Ann Robertson-Tait

Geothermal energy extraction is typically achieved by use of long open-hole intervals in an attempt to connect the well with the greatest possible rock mass. This presents a problem for the development of Enhanced (Engineered) Geothermal Systems (EGS), owing to the challenge of obtaining uniform stimulation throughout the open-hole interval. Fluids are often injected in only a fraction of that interval, reducing heat transfer efficiency and increasing energy cost. Pinnacle Technologies, Inc. and GeothermEx, Inc. evaluated a variety of techniques and methods that are commonly used for hydraulic fracturing of oil and gas wells to increase and evaluate stimulation effectivenessmore » in EGS wells. Headed by Leen Weijers, formerly Manager of Technical Development at Pinnacle Technologies, Inc., the project ran from August 1, 2004 to July 31, 2006 in two one-year periods to address the following tasks and milestones: 1) Analyze stimulation results from the closest oil-field equivalents for EGS applications in the United States (e.g., the Barnett Shale in North Texas) (section 3 on page 8). Pinnacle Technologies, Inc. has collected fracture growth data from thousands of stimulations (section 3.1 on page 12). This data was further evaluated in the context of: a) Identifying techniques best suited to developing a stimulated EGS fracture network (section 3.2 on page 29), and b) quantifying the growth of the network under various conditions to develop a calibrated model for fracture network growth (section 3.3 on page 30). The developed model can be used to design optimized EGS fracture networks that maximize contact with the heat source and minimize short-circuiting (section 3.4 on page 38). 2) Evaluate methods used in oil field applications to improve fluid diversion and penetration and determine their applicability to EGS (section 4 on page 50). These methods include, but are not limited to: a) Stimulation strategies (propped fracturing versus water fracturing versus injecting fluid below fracturing gradients) (section 4.1 on page 50); b) zonal isolation methods (by use of perforated casing or packers) (section 4.2 on page 57); c) fracture re-orientation and fracture network growth techniques (e.g., by use of alternating high- and low-rate injections) (section 4.4 on page 74); and d) fluid diversion methods (by use of the SurgiFrac technique, the StimGun perforation technique, or stress shadowing). This project task is to be completed in the first project year, enabling the most promising techniques to be field tested and evaluated in the second project year. 3) Study the applicability of the methods listed above by utilizing several techniques (section 5 on page 75) including, but not limited to: a) Hydraulic Impedance Testing (HIT) to determine the location of open hydraulic fractures along a open-hole interval; b) pressure transient testing to determine reservoir permeability, pore pressure, and closure stress; and c) treatment well tilt mapping or microseismic mapping to evaluate fracture coverage. These techniques were reviewed for their potential application for EGS in the first project year (section 5.1 on page 75). This study also includes further analysis of any field testing that will be conducted in the Desert Peak area in Nevada for ORMAT Nevada, Inc. (section 5.2 on page 86), with the aim to close the loop to provide reliable calibrated fracture model results. Developed through its hydraulic fracture consulting business, techniques of Pinnacle Technologies, Inc. for stimulating and analyzing fracture growth have helped the oil and gas industry to improve hydraulic fracturing from both a technical and economic perspective. In addition to more than 30 years of experience in the development of geothermal energy for commercial power generation throughout the world, GeothermEx, Inc. brings to the project: 1) Detailed information about specific developed and potential EGS reservoirs, 2) experience with geothermal well design, completion, and testing practices, and 3) a direct connection to the Desert Peak EGS project.« less

Application of EREP imagery to fracture-related mine safety hazards and environmental problems in mining

NASA Technical Reports Server (NTRS)

Wier, C. E.; Wobber, F. J.; Amato, R. V.; Russell, O. R. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Numerous fracture traces were detected on both the color transparencies and black and white spectral bands. Fracture traces of value to mining hazards analysis were noted on the EREP imagery which could not be detected on either the ERTS-1 or high altitude aircraft color infrared photography. Several areas of mine subsidence occurring in the Busseron Creek area near Sullivan, Indiana were successfully identified using color photography. Skylab photography affords an increase over comparable scale ERTS-1 imagery in level of information obtained in mined lands inventory and reclamation analysis. A review of EREP color photography permitted the identification of a substantial number of non-fuel mines within the Southern Indiana test area. A new mine was detected on the EREP photography without prior data. EREP has definite value for estimating areal changes in active mines and for detecting new non-fuel mines. Gob piles and slurry ponds of several acres could be detected on the S-190B color photography when observed in association with large scale mining operations. Apparent degradation of water quality resulting from acid mine drainage and/or siltation was noted in several ponds or small lakes and appear to be related to intensive mining activity near Sullivan, Indiana.

Remote optical configuration of pigmented lesion detection and diagnosis of bone fractures

NASA Astrophysics Data System (ADS)

Ozana, Nisan; Bishitz, Yael; Beiderman, Yevgeny; Garcia, Javier; Zalevsky, Zeev; Schwarz, Ariel

2016-02-01

In this paper we present a novel approach of realizing a safe, simple, and inexpensive sensor applicable to bone fractures and pigmented lesions detection. The approach is based on temporal tracking of back-reflected secondary speckle pattern generated while illuminating the affected area with a laser and applying periodic pressure to the surface via a controlled vibration. The use of such a concept was already demonstrated for non-contact monitoring of various bio-medical parameters such as heart rate, blood pulse pressure, concentration of alcohol and glucose in the blood stream and intraocular pressure. The presented technique is a safe and effective method of detecting bone fractures in populations at risk. When applied to pigmented lesions, the technique is superior to visual examination in avoiding many false positives and resultant unnecessary biopsies. Applying a series of different vibration frequencies at the examined tissue and analyzing the 2-D speckle pattern trajectory in response to the applied periodic pressure creates a unique signature for each and different pigmented lesion. Analyzing these signatures is the first step toward detection of malignant melanoma. In this paper we present preliminary experiments that show the validity of the developed sensor for both applications: the detection of damaged bones as well as the classification of pigmented lesions.

Air monitoring of volatile organic compounds at relevant receptors during hydraulic fracturing operations in Washington County, Pennsylvania.

PubMed

Maskrey, Joshua R; Insley, Allison L; Hynds, Erin S; Panko, Julie M

2016-07-01

A 3-month air monitoring study was conducted in Washington County, Pennsylvania, at the request of local community members regarding the potential risks resulting from air emissions of pollutants related to hydraulic fracturing operations. Continuous air monitoring for total volatile organic compounds was performed at two sampling sites, including a school and a residence, located within 900 m of a hydraulic fracturing well pad that had been drilled prior to the study. Intermittent 24-hour air samples for 62 individual volatile organic compounds were also collected. The ambient air at both sites was monitored during four distinct periods of unconventional natural gas extraction activity: an inactive period prior to fracturing operations, during fracturing operations, during flaring operations, and during another inactive period after operations. The results of the continuous monitoring during fracturing and flaring sampling periods for total volatile organic compounds were similar to the results obtained during inactive periods. Total volatile organic compound 24-hour average concentrations ranged between 0.16 and 80 ppb during all sampling periods. Several individual volatile compounds were detected in the 24-hour samples, but they were consistent with background atmospheric levels measured previously at nearby sampling sites and in other areas in Washington County. Furthermore, a basic yet conservative screening level evaluation demonstrated that the detected volatile organic compounds were well below health-protective levels. The primary finding of this study was that the operation of a hydraulic fracturing well pad in Washington County did not substantially affect local air concentrations of total and individual volatile organic compounds.

Application of remote sensor data to geologic analysis of the Bonanza test site Colorado

NASA Technical Reports Server (NTRS)

Lee, K. (Compiler); Butler, R. W.; Fisher, J. C.; Huntley, D.; Hulstrom, R. L.; Knepper, D. H., Jr.; Muhm, J. R.; Sawatzky, D. L.; Worman, K. E.; Wychgram, D.

1973-01-01

Research activities on geologic remote sensing applications for Colorado are summarized. Projects include: regional and detailed geologic mapping, surficial and engineering geology, fracture studies, uranium exploration, hydrology, and data reduction and enhancement. The acquisition of remote sensor data is also discussed.

Induction logging device with a pair of mutually perpendicular bucking coils

DOEpatents

Koelle, Alfred R.; Landt, Jeremy A.

1981-01-01

An instrument is disclosed for mapping vertical conductive fractures in a resistive bedrock, magnetically inducing eddy currents by a pair of vertically oriented, mutually perpendicular, coplanar coils. The eddy currents drive magnetic fields which are picked up by a second, similar pair of coils.

Journal of Special Operations Medicine. Volume 10, Edition 2, Spring 2010

DTIC Science & Technology

2010-01-01

national (LN) male carried to the firebase clinic by his family in severe pain with swelling of his left thigh following a motor- Fracture Detection...tient. (Image 1a) Once the patient’s pain was controlled, the 18D used CR for comparison and con- firmation. (Image 1b) Case 2: Distal Fibular...swollen left leg. The 18D used US to confirm a suspected fracture. (Image 4a) Once the pain was con- trolled the 18D confirmed the fractured tibia with CR

The Israeli elite infantry recruit: a model for understanding the biomechanics of stress fractures.

PubMed

Milgrom, C

1989-01-01

In a series of prospective studies among infantry recruits the biomechanics of stress fractures have been studied. In this recruit model bone geometry and the natural shock absorbers of the body have been found to be related to stress fracture morbidity. Using the technique of accelerometry in this model, it has been shown that in the fatigue state shock absorption decreases, resulting in an increase in the amplitude of vertical accelerations that propagate up the skeleton at heel strike. Experiments to study the possibility of lowering stress fracture morbidity in this model by means of viscoelastic orthotics have been successful only in the case of femoral and metatarsal stress fractures among certain subpopulations. Stress fracture management in this model has been improved by early detection and by treatment regimens according to a protocol that emphasizes limited rest periods to allow healing to take place rather than judging recovery by pain levels.

Hydraulic fracture orientation and production/injection induced reservoir stress changes in diatomite waterfloods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, C.A.; Conant, R.A.; Golich, G.M.

1995-12-31

This paper summarizes the (preliminary) findings from extensive field studies of hydraulic fracture orientation in diatomite waterfloods and related efforts to monitor the induced surface subsidence. Included are case studies from the Belridge and Lost Hills diatomite reservoirs. The primary purpose of the paper is to document a large volume of tiltmeter hydraulic fracture orientation data that demonstrates waterflood-induced fracture reorientation--a phenomenon not previously considered in waterflood development planning. Also included is a brief overview of three possible mechanisms for the observed waterflood fracture reorientation. A discussion section details efforts to isolate the operative mechanism(s) from the most extensive casemore » study, as well as suggesting a possible strategy for detecting and possibly mitigating some of the adverse effects of production/injection induced reservoir stress changes--reservoir compaction and surface subsidence as well as fracture reorientation.« less

Geologic map of the Montoso Peak quadrangle, Santa Fe and Sandoval Counties, New Mexico

USGS Publications Warehouse

Thompson, Ren A.; Hudson, Mark R.; Shroba, Ralph R.; Minor, Scott A.; Sawyer, David A.

2011-01-01

The Montoso Peak quadrangle is underlain by volcanic rocks and associated sediments of the Cerros del Rio volcanic field in the southern part of the Española Basin that record volcanic, faulting, alluvial, colluvial, and eolian processes over the past three million years. The geology was mapped from 1997 to 1999 and modified in 2004 to 2008. The geologic mapping was carried out in support of the U.S. Geological Survey (USGS) Rio Grande Basin Project, funded by the USGS National Cooperative Geologic mapping Program. The mapped distribution of units is based primarily on interpretation of 1:16,000-scale, color aerial photographs taken in 1992, and 1:40,000-scale, black-and-white, aerial photographs taken in 1996. Most of the contacts on the map were transferred from the aerial photographs using a photogrammetric stereoplotter and subsequently field checked for accuracy and revised based on field determination of allostratigraphic and lithostratigraphic units. Determination of lithostratigraphic units in volcanic deposits was aided by geochemical data, 40Ar/39Ar geochronology, aeromagnetic and paleomagnetic data. Supplemental revision of mapped contacts was based on interpretation of USGS 1-meter orthoimagery. This version of the Montoso Peak quadrangle geologic map uses a traditional USGS topographic base overlain on a shaded relief base generated from 10-m digital elevation model (DEM) data from the USGS National Elevation Dataset (NED). Faults are identified with varying confidence levels in the map area. Recognizing and mapping faults developed near the surface in young, brittle volcanic rocks is difficult because (1) they tend to form fractured zones tens of meters wide rather than discrete fault planes, (2) the youth of the deposits has allowed only modest displacements to accumulate for most faults, and (3) many may have significant strike-slip components that do not result in large vertical offsets that are readily apparent in offset of sub-horizontal contacts. Those faults characterized as "certain" either have distinct offset of map units or had slip planes that were directly observed in the field. Faults classed as "inferred" were traced based on linear alignments of geologic, topographic and aerial photo features such as vents, lava flow edges, and drainages inferred to preferentially develop on fractured rock. Lineaments defined from magnetic anomalies form an additional constraint on potential fault locations.

[FRAX® thresholds to identify people with high or low risk of osteoporotic fracture in Spanish female population].

PubMed

Azagra, Rafael; Roca, Genís; Martín-Sánchez, Juan Carlos; Casado, Enrique; Encabo, Gloria; Zwart, Marta; Aguyé, Amada; Díez-Pérez, Adolf

2015-01-06

To detect FRAX(®) threshold levels that identify groups of the population that are at high/low risk of osteoporotic fracture in the Spanish female population using a cost-effective assessment. This is a cohort study. Eight hundred and sixteen women 40-90 years old selected from the FRIDEX cohort with densitometry and risk factors for fracture at baseline who received no treatment for osteoporosis during the 10 year follow-up period and were stratified into 3 groups/levels of fracture risk (low<10%, 10-20% intermediate and high>20%) according to the real fracture incidence. The thresholds of FRAX(®) baseline for major osteoporotic fracture were: low risk<5; intermediate ≥ 5 to <7.5 and high ≥ 7.5. The incidence of fracture with these values was: low risk (3.6%; 95% CI 2.2-5.9), intermediate risk (13.7%; 95% CI 7.1-24.2) and high risk (21.4%; 95% CI12.9-33.2). The most cost-effective option was to refer to dual energy X-ray absorptiometry (DXA-scan) for FRAX(®)≥ 5 (Intermediate and high risk) to reclassify by FRAX(®) with DXA-scan at high/low risk. These thresholds select 17.5% of women for DXA-scan and 10% for treatment. With these thresholds of FRAX(®), compared with the strategy of opportunistic case finding isolated risk factors, would improve the predictive parameters and reduce 82.5% the DXA-scan, 35.4% osteoporosis prescriptions and 28.7% cost to detect the same number of women who suffer fractures. The use of FRAX ® thresholds identified as high/low risk of osteoporotic fracture in this calibration (FRIDEX model) improve predictive parameters in Spanish women and in a more cost-effective than the traditional model based on the T-score ≤ -2.5 of DXA scan. Copyright © 2013 Elsevier España, S.L.U. All rights reserved.

Sonographic Findings of Chondral Avulsion Fractures of the Lateral Ankle Ligaments in Children.

PubMed

Maeda, Manabu; Maeda, Nana; Takaoka, Takanori; Tanaka, Yasuhito

2017-02-01

In this series, we aimed to describe the sonographic findings of chondral avulsion fractures that develop concomitant with lateral ankle ligament injury in children. We performed stress sonography during a manual anterior drawer stress procedure of the ankle in 9 skeletally immature patients who had recently had a lateral ankle sprain. Echo videos were obtained through the course of treatment, and all videos were reviewed. We elucidated the common features of chondral avulsion fractures of the lateral ankle ligaments in the children. The features of avulsion fractures on conventional sonography included absence of a fracture with hyperechoic spots (sonographic occult fracture type), cortical discontinuity with hyperechoic spots (cortical disruption fracture type), fracture line in the cortical bone (double-line fracture type), and a step-off deformity of the cortical bone with cartilage (displaced fracture type). In contrast, the features of chondral fractures on stress sonography included abnormal motion of the chondral lesions and mobility/fluidity of hyperechoic spots along the chondral fracture site. The presence of hyperechoic spots around the chondral lesion is an important sonographic sign for diagnosing chondral fractures concomitant with ankle lateral ligament injury. Hence, we believe that stress sonography should be considered for the detection of chondral fractures concomitant with radiographically negative ankle lateral ligament injuries in skeletally immature patients with lateral ankle pain and ankle sprains, if hyperechoic spots are present in the cartilage of the distal fibula. © 2017 by the American Institute of Ultrasound in Medicine.

The utility of dual-energy X-ray absorptiometry, calcaneal quantitative ultrasound, and fracture risk indices (FRAX® and Osteoporosis Risk Assessment Instrument) for the identification of women with distal forearm or hip fractures: A pilot study.

PubMed

Esmaeilzadeh, Sina; Cesme, Fatih; Oral, Aydan; Yaliman, Ayse; Sindel, Dilsad

2016-08-01

Dual-energy X-ray absorptiometry (DXA) is considered the "gold standard" in predicting osteoporotic fractures. Calcaneal quantitative ultrasound (QUS) variables are also known to predict fractures. Fracture risk assessment tools may also guide us for the detection of individuals at high risk for fractures. The aim of this case-control study was to evaluate the utility of DXA bone mineral density (BMD), calcaneal QUS parameters, FRAX® (Fracture Risk Assessment Tool), and Osteoporosis Risk Assessment Instrument (ORAI) for the discrimination of women with distal forearm or hip fractures. This case-control study included 20 women with a distal forearm fracture and 18 women with a hip fracture as cases and 76 age-matched women served as controls. BMD at the spine, proximal femur, and radius was measured using DXA and acoustic parameters of bone were obtained using a calcaneal QUS device. FRAX® 10-year probability of fracture and ORAI scores were also calculated in all participants. Receiver operating characteristic (ROC) analysis was used to assess fracture discriminatory power of all the tools. While all DXA BMD, and QUS variables and FRAX® fracture probabilities demonstrated significant areas under the ROC curves for the discrimination of hip-fractured women and those without, only 33% radius BMD, broadband ultrasound attenuation (BUA), and FRAX® major osteoporotic fracture probability calculated without BMD showed significant discriminatory power for distal forearm fractures. It can be concluded that QUS variables, particularly BUA, and FRAX® major osteoporotic fracture probability without BMD are good candidates for the identification of both hip and distal forearm fractures.

Effect of Metal Artifacts on Detection of Vertical Root Fractures Using Two Cone Beam Computed Tomography Systems.

PubMed

Safi, Yaser; Aghdasi, Mohammad Mehdi; Ezoddini-Ardakani, Fatemeh; Beiraghi, Samira; Vasegh, Zahra

2015-01-01

Vertical root fracture (VRF) is common in endodontically treated teeth. Conventional and digital radiographies have limitations for detection of VRFs. Cone-beam computed tomography (CBCT) offers greater detection accuracy of VRFs in comparison with conventional radiography. This study compared the effects of metal artifacts on detection of VRFs by using two CBCT systems. Eighty extracted premolars were selected and sectioned at the level of the cemento enamel junction (CEJ). After preparation, root canals were filled with gutta-percha. Subsequently, two thirds of the root fillings were removed for post space preparation and a custom-made post was cemented into each canal. The teeth were randomly divided into two groups (n=40). In the test group, root fracture was created with Instron universal testing machine. The control teeth remained intact. CBCT scans of all teeth were obtained with either New Tom VGI or Soredex Scanora 3D. Three observers analyzed the images for detection of VRF. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for VRF detection and percentage of probable cases were calculated for each imaging system and compared using non-parametric tests considering the non-normal distribution of data. The inter-observer reproducibility was calculated using the weighted kappa coefficient. There were no statistically significant differences in sensitivity, specificity, PPV and NPV between the two CBCT systems. The effect of metal artifacts on VRF detection was not significantly different between the two CBCT systems.

Consistent Practices for the Probability of Detection (POD) of Fracture Critical Metallic Components Project

NASA Technical Reports Server (NTRS)

Hughitt, Brian; Generazio, Edward (Principal Investigator); Nichols, Charles; Myers, Mika (Principal Investigator); Spencer, Floyd (Principal Investigator); Waller, Jess (Principal Investigator); Wladyka, Jordan (Principal Investigator); Aldrin, John; Burke, Eric; Cerecerez, Laura;

A novel registration-based methodology for prediction of trabecular bone fabric from clinical QCT: A comprehensive analysis

PubMed Central

Reyes, Mauricio; Zysset, Philippe

2017-01-01

Osteoporosis leads to hip fractures in aging populations and is diagnosed by modern medical imaging techniques such as quantitative computed tomography (QCT). Hip fracture sites involve trabecular bone, whose strength is determined by volume fraction and orientation, known as fabric. However, bone fabric cannot be reliably assessed in clinical QCT images of proximal femur. Accordingly, we propose a novel registration-based estimation of bone fabric designed to preserve tensor properties of bone fabric and to map bone fabric by a global and local decomposition of the gradient of a non-rigid image registration transformation. Furthermore, no comprehensive analysis on the critical components of this methodology has been previously conducted. Hence, the aim of this work was to identify the best registration-based strategy to assign bone fabric to the QCT image of a patient’s proximal femur. The normalized correlation coefficient and curvature-based regularization were used for image-based registration and the Frobenius norm of the stretch tensor of the local gradient was selected to quantify the distance among the proximal femora in the population. Based on this distance, closest, farthest and mean femora with a distinction of sex were chosen as alternative atlases to evaluate their influence on bone fabric prediction. Second, we analyzed different tensor mapping schemes for bone fabric prediction: identity, rotation-only, rotation and stretch tensor. Third, we investigated the use of a population average fabric atlas. A leave one out (LOO) evaluation study was performed with a dual QCT and HR-pQCT database of 36 pairs of human femora. The quality of the fabric prediction was assessed with three metrics, the tensor norm (TN) error, the degree of anisotropy (DA) error and the angular deviation of the principal tensor direction (PTD). The closest femur atlas (CTP) with a full rotation (CR) for fabric mapping delivered the best results with a TN error of 7.3 ± 0.9%, a DA error of 6.6 ± 1.3% and a PTD error of 25 ± 2°. The closest to the population mean femur atlas (MTP) using the same mapping scheme yielded only slightly higher errors than CTP for substantially less computing efforts. The population average fabric atlas yielded substantially higher errors than the MTP with the CR mapping scheme. Accounting for sex did not bring any significant improvements. The identified fabric mapping methodology will be exploited in patient-specific QCT-based finite element analysis of the proximal femur to improve the prediction of hip fracture risk. PMID:29176881

The use of multifrequency and polarimetric SIR-C/X-SAR data in geologic studies of Bir Safsaf, Egypt

USGS Publications Warehouse

Schaber, G.G.; McCauley, J.F.; Breed, C.S.

1997-01-01

Bir Safsaf, within the hyperarid 'core' of the Sahara in the Western Desert of Egypt, was recognized following the SIR-A and SIR-B missions in the 1980s as one of the key localities in northeast Africa, where penetration of dry sand by radar signals delineates previously unknown, sand-buried paleodrainage valleys ('radar-rivers') of middle Tertiary to Quaternary age. The Bir Safsaf area was targeted as a focal point for further research in sand penetration and geologic mapping using the multifrequency and polarimetric SIR-C/X-SAR sensors. Analysis of the SIR-C/X-SAR data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat TM images by a relatively thin, but extensive blanket of blow sand. Basement rock units (granitoids and gneisses) and the fractures associated with them at Bir Safsaf are shown here for the first time to be clearly delineated using C- and L-band SAR images. The detectability of most geologic features is dependent primarily on radar frequency, as shown for wind erosion patterns in bedrock at X-band (3 cm wavelength), and for geologic units and sand and clay-filled fractures in weathered crystal-line basement rocks at C-band (6 cm) and L-band (24 cm). By contrast, Quaternary paleodrainage channels are detectable at all three radar frequencies owing, among other things, to an usually thin cover of blow sand. The SIR-C/X-SAR data investigated to date enable us to make specific recommendations about the utility of certain radar sensor configurations for geologic and paleoenvironmental reconnaissance in desert regions.Analysis of the shuttle imaging radar-C/X-synthetic aperture radar (SIR-C/X-SAR) data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat images by a relatively thin, but extensive blanket of blow sand. Basement rock units and associated fractures at the Bir Safsaf are clearly delineated using C- and L-band SAR images. The detectability of most geologic features depend primarily on radar frequency. The SIR-C/X-SAR data also provide recommendations about the utility of certain radar configurations for geologic and paleoenvironmental reconnaissance in deserts.

Comprehensive process maps for synthesizing high density aluminum oxide-carbon nanotube coatings by plasma spraying for improved mechanical and wear properties

NASA Astrophysics Data System (ADS)

Keshri, Anup Kumar

Plasma sprayed aluminum oxide ceramic coating is widely used due to its outstanding wear, corrosion, and thermal shock resistance. But porosity is the integral feature in the plasma sprayed coating which exponentially degrades its properties. In this study, process maps were developed to obtain Al2O3-CNT composite coatings with the highest density (i.e. lowest porosity) and improved mechanical and wear properties. Process map is defined as a set of relationships that correlates large number of plasma processing parameters to the coating properties. Carbon nanotubes (CNTs) were added as reinforcement to Al2O 3 coating to improve the fracture toughness and wear resistance. Two novel powder processing approaches viz spray drying and chemical vapor growth were adopted to disperse CNTs in Al2O3 powder. The degree of CNT dispersion via chemical vapor deposition (CVD) was superior to spray drying but CVD could not synthesize powder in large amount. Hence optimization of plasma processing parameters and process map development was limited to spray dried Al2O3 powder containing 0, 4 and 8 wt. % CNTs. An empirical model using Pareto diagram was developed to link plasma processing parameters with the porosity of coating. Splat morphology as a function of plasma processing parameter was also studied to understand its effect on mechanical properties. Addition of a mere 1.5 wt. % CNTs via CVD technique showed ˜27% and ˜24% increase in the elastic modulus and fracture toughness respectively. Improved toughness was attributed to combined effect of lower porosity and uniform dispersion of CNTs which promoted the toughening by CNT bridging, crack deflection and strong CNT/Al2O3 interface. Al2O 3-8 wt. % CNT coating synthesized using spray dried powder showed 73% improvement in the fracture toughness when porosity reduced from 4.7% to 3.0%. Wear resistance of all coatings at room and elevated temperatures (573 K, 873 K) showed improvement with CNT addition and decreased porosity. Such behavior was due to improved mechanical properties, protective film formation due to tribochemical reaction, and CNT bridging between the splats. Finally, process maps correlating porosity content, CNT content, mechanical properties, and wear properties were developed.

A method to evaluate hydraulic fracture using proppant detection.

PubMed

Liu, Juntao; Zhang, Feng; Gardner, Robin P; Hou, Guojing; Zhang, Quanying; Li, Hu

2015-11-01

Accurate determination of the proppant placement and propped fracture height are important for evaluating and optimizing stimulation strategies. A technology using non-radioactive proppant and a pulsed neutron gamma energy spectra logging tool to determine the placement and height of propped fractures is proposed. Gd2O3 was incorporated into ceramic proppant and a Monte Carlo method was utilized to build the logging tools and formation models. Characteristic responses of the recorded information of different logging tools to fracture widths, proppant concentrations and influencing factors were studied. The results show that Gd capture gamma rays can be used to evaluate propped fractures and it has higher sensitivity to the change of fracture width and traceable proppant content compared with the exiting non-radioactive proppant evaluation techniques and only an after-fracture measurement is needed for the new method; The changes in gas saturation and borehole size have a great impact on determining propped fractures when compensated neutron and pulsed neutron capture tool are used. A field example is presented to validate the application of the new technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

SHARAD Penetrates Only the Youngest Geological Units on Mars

NASA Astrophysics Data System (ADS)

Stillman, D.; Grimm, R. E.

2009-12-01

The SHAllow RADar (SHARAD) instrument on the Mars Reconnaissance Orbiter was intended to receive echoes from up to 1 km deep in the rocky martian subsurface. Such deep penetration only occurs in the icy polar caps and in certain ice-rich units. In fact, over the majority of the rocky units of Mars, only surface echoes are detected. Therefore, rocky units are more attenuating than expected. To gain insight into the cause of this attenuation, we correlated SHARAD subsurface reflectors with a geologic map of the northern plains of Mars [Tanaka et al., 2005]. Our survey was restricted to this area due to general smoother topography and hence less potential influence of surface scattering (clutter). All released SHARAD data (approximately 1,500 radargrams) overlying the geologic map were individually interpreted. Geologic units were categorized by their map description into ice-rich, pristine volcanic, and water-altered units. The last category comprises units interpreted to be fluvial, lacustrine, or periglacial in origin, as well as volcanic and other units that were subsequently altered by water or ice. Radar reflections in each unit were further categorized as abundant, occasional, or none. We found that abundant reflections are only detected in geologic units that are Amazonian in age, and ice-rich or pristine volcanic. No reflections are seen in water altered units. Occasional reflections are detected in Hesperian-aged pristine volcanic units. We propose two endmember hypotheses for this attenuation behavior, scattering and absorption, but they could act jointly. The young pristine volcanic units that SHARAD penetrates consist of thick (about 50 m) flood basalts or tuff. These units are expected to have cooling joints in them, but little if any other heterogeneity; therefore their scattering loss should be small. With increasing age and thermoelastic stress due to global cooling and contraction, these previously homogeneous volcanics could become increasingly fractured, thus more efficient at scattering. Under this hypothesis, all of the water-altered units have significant subwavelength heterogeneity due to their primary mode of origin or secondary alteration. Alternatively, absorption due to the dielectric relaxation of adsorbed water could influence the attenuation. Alteration minerals such as phyllosilicates and palagonite drastically increase the surface area and can hold up to three monolayers of adsorbed water at martian temperatures. Our lab measurements indicate that about 6% phyllosilicates or 15% palagonite by volume can completely attenuate the reflected signal of an interface at a depth of 30 m; which is the shallowest depth SHARAD can detect due to sidelobe effects. These minerals would not be confined to Noachian units as currently suggested by orbital spectroscopy. A smaller proportion of hydrated minerals could be accommodated if the shallow geotherm is steep, or if alteration minerals are below the detection threshold due to their degree of hydration or grain size. In either case, subsurface radar attenuation on Mars is less than that of the Earth, but more than that of the Moon. Tanaka, K.L., J.A. Skinner, and T.M. Hare (2005) Geologic map of the northern plains of Mars, USGS Sci. Invest. Map, 2888.

Mydriasis during Orbital Floor Fracture Reconstruction: A Novel Diagnostic and Treatment Algorithm

PubMed Central

Yeo, Matthew S.; Al-Mousa, Radwan; Sundar, Gangadhara; Lim, Thiam Chye

2010-01-01

Orbital floor fractures are the most commonly encountered traumatic fractures in the facial skeleton. Mydriasis that is detected during orbital floor fracture reconstruction may cause significant distress to surgeons, as it may be associated with sinister events such as visual loss. It is not an uncommon problem; previous studies have shown the incidence of mydriasis to be 2.1%. The combination of careful preoperative evaluation and planning, as well as specific intraoperative investigations when mydriasis is encountered, can be immensely valuable in allaying surgeons' anxiety during orbital floor fracture reconstruction. In this review article, the authors discuss the common causes of mydriasis and present a novel systematic approach to its diagnostic evaluation devised by our unit that has been successfully implemented since 2008. PMID:22132259

Computed tomography of calcaneal fractures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heger, L.; Wulff, K.; Seddiqi, M.S.A.

1985-07-01

Computed tomography (CT) of 25 fractured calcanei was performed to investigate the potential of CT in evaluating the pattern and biomechanics of these fractures. The characteristic findings of typical fractures are presented, including the number and type of principal fragments, size and dislocation of the sustentacular fragment, and involvement of the anterior and posterior facets of the subtalar joint. In 17 cases, the calcaneus consisted of four or more fragments. Furthermore, in 17 cases the sustentacular fragment included all or part of the posterior facet joint. In 18 of the 25 cases, the sustentacular fragment was displaced. It is concludedmore » that well performed CT is an invaluable adjunct in understanding the fracture mechanism and in detecting pain-provoking impingement between the fibular malleolus and the tuberosity fragment.« less

Geologic map of south-central Yucca Mountain, Nye County, Nevada

USGS Publications Warehouse

Dickerson, Robert P.; Drake II, Ronald M.

2004-01-01

New 1:6,000-scale geologic mapping in a 20-square-kilometer area near the south end of Yucca Mountain, Nevada, which is the proposed site of an underground repository for the storage of high-level radioactive wastes, substantially supplements the stratigraphic and structural data obtained from earlier, 1:24,000-scale mapping. Principal observations and interpretations resulting from the larger scale, more detailed nature of the recent investigation include: (1) the thickness of the Miocene Tiva Canyon Tuff decreases from north to south within the map area, and the lithophysal zones within the formation have a greater lateral variability than in areas farther north; and (2) fault relations are far more complex than shown on previous maps, with both major (block-bounding) and minor (intrablock) faults showing much lateral variation in (a) the number of splays and (b) the amount, distribution, and width of anastomosing breccia and fracture zones.

Space moving target detection using time domain feature

NASA Astrophysics Data System (ADS)

Wang, Min; Chen, Jin-yong; Gao, Feng; Zhao, Jin-yu

2018-01-01

The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects (target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10-5, which outperforms those of compared algorithms.

Quartz c-axis orientation patterns in fracture cement as a measure of fracture opening rate and a validation tool for fracture pattern models

DOE PAGES

Ukar, Estibalitz; Laubach, Stephen E.; Marrett, Randall

2016-03-09

Here, we evaluate a published model for crystal growth patterns in quartz cement in sandstone fractures by comparing crystal fracture-spanning predictions to quartz c-axis orientation distributions measured by electron backscatter diffraction (EBSD) of spanning quartz deposits. Samples from eight subvertical opening-mode fractures in four sandstone formations, the Jurassic– Cretaceous Nikanassin Formation, northwestern Alberta Foothills (Canada), Cretaceous Mesaverde Group (USA; Cozzette Sandstone Member of the Iles Formation), Piceance Basin, Colorado (USA), and upper Jurassic–lower Cretaceous Cotton Valley Group (Taylor sandstone) and overlying Travis Peak Formation, east Texas, have similar quartzose composition and grain size but contain fractures with different temperature historiesmore » and opening rates based on fluid inclusion assemblages and burial history. Spherical statistical analysis shows that, in agreement with model predictions, bridging crystals have a preferred orientation with c-axis orientations at a high angle to fracture walls. The second form of validation is for spanning potential that depends on the size of cut substrate grains. Using measured cut substrate grain sizes and c-axis orientations of spanning bridges, we calculated the required orientation for the smallest cut grain to span the maximum gap size and the required orientation of the crystal with the least spanning potential to form overgrowths that span across maximum measured gap sizes. We find that within a 10° error all spanning crystals conform to model predictions. Using crystals with the lowest spanning potential based on crystallographic orientation (c-axis parallel to fracture wall) and a temperature range for fracture opening measured from fluid inclusion assemblages, we calculate maximum fracture opening rates that allow crystals to span. These rates are comparable to those derived independently from fracture temperature histories based on burial history and multiple sequential fluid inclusion assemblages. Results support the R. Lander and S. Laubach model, which predicts that for quartz deposited synchronously with fracture opening, spanning potential, or likelihood of quartz deposits that are thick enough to span between fracture walls, depends on temperature history, fracture opening rate, size of opening increments, and size, mineralogy, and crystallographic orientation of substrates in the fracture wall (transected grains). Results suggest that EBSD maps, which can be more rapidly acquired than measurement of tens to hundreds of fluid inclusion assemblages, can provide a useful measure of relative opening rates within populations of quartz-filled fractures formed under sedimentary basin conditions. Such data are useful for evaluating fracture pattern development models.« less

Quartz c-axis orientation patterns in fracture cement as a measure of fracture opening rate and a validation tool for fracture pattern models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ukar, Estibalitz; Laubach, Stephen E.; Marrett, Randall

Here, we evaluate a published model for crystal growth patterns in quartz cement in sandstone fractures by comparing crystal fracture-spanning predictions to quartz c-axis orientation distributions measured by electron backscatter diffraction (EBSD) of spanning quartz deposits. Samples from eight subvertical opening-mode fractures in four sandstone formations, the Jurassic– Cretaceous Nikanassin Formation, northwestern Alberta Foothills (Canada), Cretaceous Mesaverde Group (USA; Cozzette Sandstone Member of the Iles Formation), Piceance Basin, Colorado (USA), and upper Jurassic–lower Cretaceous Cotton Valley Group (Taylor sandstone) and overlying Travis Peak Formation, east Texas, have similar quartzose composition and grain size but contain fractures with different temperature historiesmore » and opening rates based on fluid inclusion assemblages and burial history. Spherical statistical analysis shows that, in agreement with model predictions, bridging crystals have a preferred orientation with c-axis orientations at a high angle to fracture walls. The second form of validation is for spanning potential that depends on the size of cut substrate grains. Using measured cut substrate grain sizes and c-axis orientations of spanning bridges, we calculated the required orientation for the smallest cut grain to span the maximum gap size and the required orientation of the crystal with the least spanning potential to form overgrowths that span across maximum measured gap sizes. We find that within a 10° error all spanning crystals conform to model predictions. Using crystals with the lowest spanning potential based on crystallographic orientation (c-axis parallel to fracture wall) and a temperature range for fracture opening measured from fluid inclusion assemblages, we calculate maximum fracture opening rates that allow crystals to span. These rates are comparable to those derived independently from fracture temperature histories based on burial history and multiple sequential fluid inclusion assemblages. Results support the R. Lander and S. Laubach model, which predicts that for quartz deposited synchronously with fracture opening, spanning potential, or likelihood of quartz deposits that are thick enough to span between fracture walls, depends on temperature history, fracture opening rate, size of opening increments, and size, mineralogy, and crystallographic orientation of substrates in the fracture wall (transected grains). Results suggest that EBSD maps, which can be more rapidly acquired than measurement of tens to hundreds of fluid inclusion assemblages, can provide a useful measure of relative opening rates within populations of quartz-filled fractures formed under sedimentary basin conditions. Such data are useful for evaluating fracture pattern development models.« less

Cross-validated detection of crack initiation in aerospace materials

NASA Astrophysics Data System (ADS)

Vanniamparambil, Prashanth A.; Cuadra, Jefferson; Guclu, Utku; Bartoli, Ivan; Kontsos, Antonios

2014-03-01

A cross-validated nondestructive evaluation approach was employed to in situ detect the onset of damage in an Aluminum alloy compact tension specimen. The approach consisted of the coordinated use primarily the acoustic emission, combined with the infrared thermography and digital image correlation methods. Both tensile loads were applied and the specimen was continuously monitored using the nondestructive approach. Crack initiation was witnessed visually and was confirmed by the characteristic load drop accompanying the ductile fracture process. The full field deformation map provided by the nondestructive approach validated the formation of a pronounced plasticity zone near the crack tip. At the time of crack initiation, a burst in the temperature field ahead of the crack tip as well as a sudden increase of the acoustic recordings were observed. Although such experiments have been attempted and reported before in the literature, the presented approach provides for the first time a cross-validated nondestructive dataset that can be used for quantitative analyses of the crack initiation information content. It further allows future development of automated procedures for real-time identification of damage precursors including the rarely explored crack incubation stage in fatigue conditions.