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1

On the Design of Vertical Hydraulic Fractures  

Microsoft Academic Search

Some of the assumptions involved in designing vertical hydraulic fractures should be critically examined as to their validity. This is done on the basis of a new width equation and a numerical design procedure. It is found that some of the assumptions related to the fluid mechanics of the problem greatly affect the computed results and therefore deserve special attention.

Abbas Daneshy

1973-01-01

2

Pressure Responses of a Vertically Hydraulic Fractured Well in a Reservoir with Fractal Structure  

E-print Network

We obtain an analytical solution for the pressure-transient behavior of a vertically hydraulic fractured well in a heterogeneous reservoir. The heterogeneity of the reservoir is modeled by using the concept of fractal geometry. Such reservoirs are called fractal reservoirs. According to the theory of fractional calculus, a temporal fractional derivative is applied to incorporate the memory properties of the fractal reservoir. The effect of different parameters on the computed wellbore pressure is fully investigated by various synthetic examples.

Razminia, Kambiz; Torres, Delfim F M

2015-01-01

3

Hydraulic fracturing-1  

SciTech Connect

This book contains papers on hydraulic fracturing. Topics covered include: An overview of recent advances in hydraulic fracturing technology; Containment of massive hydraulic fracture; and Fracturing with a high-strength proppant.

Not Available

1990-01-01

4

The calculation of proppant transport in vertical hydraulic fractures using finite difference techniques  

E-print Network

. The theo- retical tiasis and supporting equations which describe the dynamic velo- city of a proppant in a fracturing fluid were first oresented by Uaneshy 6 This analytical method of predicting proppant transport is based on the particle trajectory... l artla1 fulfH1nient of ! he reOu!no sent Inn tn- d gnee of THE CALCULATION OF PROPPANT TRANSPORT IN VERTICAL HYDRAULIC FRACTLIRES USING FiliITE DIFFERENCE TECHfiIljUES A Thesis ROBERT WINSTON RASOR Approved as to styie and content by...

Rasor, Robert Winston

2012-06-07

5

Characteristics of high resolution hydraulic head profiles and vertical gradients in fractured sedimentary rocks  

NASA Astrophysics Data System (ADS)

Accurately identifying the position of vertical hydraulic conductivity (Kv) contrasts is critical to the delineation of hydrogeologic units that serve as the basis for conceptual and numerical models of groundwater flow. High resolution head profiles have identified the position and thickness of Kv contrasts in clayey aquitards but this potential has not yet been thoroughly evaluated in sedimentary rocks. This paper describes an experiment in which head profiles with the highest, technically feasible resolution were obtained using Westbay® multilevel systems (MLS) installed in 15 cored holes at three sedimentary rock research sites with contrasting geologic and flow system conditions. MLSs were installed to maximum depths between 90 and 260 m with 2-5 monitoring zones per 10 m. Head profiles were measured over multiyear periods. The vertical component of hydraulic gradient (i.e., vertical gradient) was calculated for each pair of adjacent monitoring intervals in every MLS and then categorized based on its repeatability to facilitate interpretation of Kv contrasts and comparisons within boreholes, between boreholes at the same site, and between sites. The head and vertical gradient profiles from all three sites display systematic (i.e., simple, geometric) shapes defined by repeatable intervals of no to minimal vertical gradient, indicating relatively high Kv units, bounded by shorter depth intervals with large (up to -50 m/m) vertical gradients, indicating relatively low Kv units. The systematic nature of the profiles suggests flow in regular and interconnected fracture networks rather than dominated by a few key fractures with irregular orientations. The low Kv units were typically thin, with their positions and thicknesses not predicted by lithostratigraphy or detailed lithologic, geophysical, and horizontal hydraulic conductivity data. Hence, the position and thickness of units with contrasting Kv would not be evident if MLSs with the conventional number of monitoring zones had been used. Furthermore, the detailed profiles can be strongly diagnostic of hydrogeologic unit boundaries or layers and can be used to improve the quantitative assessment of flow system conditions that is foundational to understanding contaminant plume migration.

Meyer, Jessica R.; Parker, Beth L.; Cherry, John A.

2014-09-01

6

Hydraulic Fracturing Sand  

USGS Multimedia Gallery

Fine-grained silica sand is mixed with chemicals and water before being pumped into rock formations to prevent the newly created artificial fractures from closing after hydraulic fracturing is completed....

7

Suspensions in hydraulic fracturing  

Microsoft Academic Search

Suspensions or slurries are widely used in well stimulation and hydraulic fracturing processes to enhance the production of oil and gas from the underground hydrocarbon-bearing formation. The success of these processes depends significantly upon having a thorough understanding of the behavior of suspensions used. Therefore, the characterization of suspensions under realistic conditions, for their rheological and hydraulic properties, is very

Shah

1996-01-01

8

What Is Hydraulic Fracturing?  

NSDL National Science Digital Library

Hydraulic fracturing is a process used in nine out of 10 natural gas wells in the United States, where millions of gallons of water, sand and chemicals are pumped underground to break apart the rock and release the gas. Scientists are worried that the chemicals used in fracturing may pose a threat either underground or when waste fluids are handled and sometimes spilled on the surface. This poster presentation illustrates the under surface process of hydraulic fracking and the distribution flow to the market.

2012-01-01

9

Computer simulation of hydraulic fractures  

Microsoft Academic Search

We provide a brief historical background of the development of hydraulic fracturing models for use in the petroleum and other industries. We discuss scaling laws and the propagation regimes that control the growth of hydraulic fractures from the laboratory to the field scale. We introduce the mathematical equations and boundary conditions that govern the hydraulic fracturing process, and discuss numerical

J. Adachi; E. Siebrits; A. Peirce; J. Desroches

2007-01-01

10

Verification and monitoring of deep granular iron permeable reactive barriers emplaced by vertical hydraulic fracturing and injection for groundwater remediation  

NASA Astrophysics Data System (ADS)

This study evaluated the use of vertical hydraulic fracturing and injection (VHFI) to emplace granular iron as a deep passive treatment system to remove organic contaminants from groundwater at the Massachusetts Military Reservation on Cape Cod, Massachusetts. It was the first permeable reactive barrier (PRB) constructed at a depth greater than 15 m below the ground surface. VHFI propagates a vertical fracture from a slot cut through the injection-well casing at a selected depth and orientation. Granular iron is suspended in a viscous fluid using a biodegradable guar polymer and pumped through the slot to form a thin vertical sheet. Two PRBs were emplaced 6 m apart and perpendicular to the groundwater flow direction with mid-depths of about 30 m below the ground surface. Due to the depth, all of the emplacement and verification methods used down-hole tools. Resistivity imaging used salt added to the guar as an electrical tracer to map the spread of the VHFI fluid for propagation control and to estimate the extent of the completed PRB. Radar tomography before and after emplacement also provided images of the PRBs and hydraulic pulse testing and electromagnetic logging provided additional data. One PRB consisted of 40 tonnes of granular iron and was estimated to be an average of 80 mm thick. Based on geophysical imaging, the 100% iron PRB was 15 m long and extended from about 24.5 to 35.5 m depth. The second PRB consisted of a mixture of 5.6 tonnes of well sand and 4.4 tonnes of iron, but was only partially completed. Based on imaging, the sand/iron PRB comprised an area 9 m long extending from about 27 to 34.5 m below the ground surface. The proximity of screened wells, which deviated significantly from vertical toward the PRB alignment, resulted in loss of VHFI control. A sub-horizontal layer of iron formed between the 100% iron PRB and several of the wells. Similarly, piping failure zones formed between the sand/iron PRB and two geophysical wells. Selected groundwater constituents were monitored up- and down-gradient of the two PRBs for 11 months before the PRB emplacement and for 48 months afterwards. Temporary elevated levels of sodium, chloride, and conductance (from the salt tracer), total organic carbon (from the guar) and lowered DO were observed down-gradient of the PRBs. Although the various verification methods confirmed the presence of the 100% iron PRB and its overall continuity, the groundwater data showed no evidence of flow through the granular iron (PCE degradation, elevated pH, dissolved oxygen removal and reducing conditions). This suggests that the groundwater flows around the 100% iron PRB. It is possible that the guar used for the VHFI remained cross-linked, creating a low-permeability barrier. In contrast, the partially completed sand/iron wall did affect the groundwater chemistry in several down-gradient wells. Reducing conditions, zero DO, high pH, and high levels of dissolved iron were noted. A reduction in PCE concentrations and formation of degradation products were observed. (Abstract shortened by UMI.)

Hubble, David Wallace

11

Hydraulic Fracture Propagation in Layered Rock: Experimental Studies of Fracture Containment  

Microsoft Academic Search

Fracture geometry is an important concern in the design of a massive hydraulic fracture for improved natural gas recovery from low-permeability reservoirs. Determination of the extent of vertical fracture growth and containment in layered rock, a priori, requires an improved understanding of the parameters that may control fracture growth across layer interfaces. We have conducted laboratory hydraulic fracture experiments and

Lawrence Teufel; James Clark

1984-01-01

12

Some Fundamental Mechanisms of Hydraulic Fracturing.  

E-print Network

??This dissertation focuses mainly on three topics: (1) mixed-mode branching and segmentation of hydraulic fractures in brittle materials, (2) hydraulic fracture propagation in particulate materials,… (more)

Wu, Ruiting

2006-01-01

13

Study of Nordgren's Equation of Hydraulic Fracturing  

Microsoft Academic Search

A nonlinear partial differential equation modeling the propagation of a vertical hydraulic fracture first derived by Nordgren is studied. When properly posed, Nordgren's derivation constitutes a Stefan problem and requires another boundary condition-namely, that the velocity of the fluid at the crack tip equals the velocity of crack propagation. With this addition, Nordgren's similarity solution in the no-leakoff case is

L. Kemp

1990-01-01

14

Hydraulic Characterization of a Fractured Granitic Aquifer  

NASA Astrophysics Data System (ADS)

Hydrogeologic testing has been conducted in a fractured granitic (quartz monzonite) bedrock aquifer to determine the hydraulic characteristics of the bedrock aquifer, determine the efficiency and performance characteristics of four extraction wells, and determine the pumping rates for the extraction wells pumping simultaneously that will provide containment of a small solvent plume under ambient conditions and under conditions of pumping a nearby water supply well. Investigative testing was conducted by drilling more than 20 deep and shallow bedrock wells and geophysical logging of two deep bedrock boreholes using caliper, conductivity, temperature, acoustic borehole televiewer, and heat-pulse borehole flowmeter. This was followed by step-drawdown testing of four deep bedrock wells, 24-hr duration constant rate pumping tests of four deep wells, and a 72-hr aquifer test with the four deep wells pumping simultaneously to complete the site characterization. These tests have revealed that a) the extraction wells are very efficient with little to no "well loss", b) the sparsely fractured bedrock has a surprisingly well-interconnected system of fractures both horizontally and vertically, c) the vertical hydraulic conductivity is generally much smaller than the horizontal but there is extensive vertical hydraulic connection throughout the aquifer, d) the aquifer exhibits anisotropic behavior with the hydraulic conductivity being approximately 6 times greater in the NW-SE direction than in the NE-SW direction, and e) the aquifer has a trend of increasing transmissivity across the site from southwest to northeast.. The hydraulic connection between two of the extraction wells is particularly good, indicating that the two are connected by a highly transmissive fracture; other anomalies in the site area have revealed a patch of nearly constant and very large hydraulic conductivity beneath a small residential development, and one bedrock well that was essentially a "dry hole". Capture zone analysis was accomplished using the data from aquifer testing and simple two-dimensional groundwater flow modeling.

Murray, W. A.

2006-12-01

15

Measuring hydraulic fracture width behind casing using radioactive proppant  

SciTech Connect

Knowing the width of hydraulic fracture behind casing can be useful in evaluating both reservoir performance and fracture design methods. This paper presents a method to obtain the widths of hydraulic fractures behind casing using radioactive, isotope-traced proppants. A tool-specific relationship between the gamma ray flux detected in a wellbore and the fracture width was developed using Monte Carlo simulation of gamma ray transport around a wellbore. This method provides fracture width estimates with a vertical resolution of about one foot. The method has been successfully used in the field and compares favorably with other methods for evaluating fracture widths.

Reis, J.S.; Fisher, K.; Holcomb, D.

1996-09-01

16

Method for directional hydraulic fracturing  

DOEpatents

A method for directional hydraulic fracturing using borehole seals to confine pressurized fluid in planar permeable regions, comprising: placing a sealant in the hole of a structure selected from geologic or cemented formations to fill the space between a permeable planar component and the geologic or cemented formation in the vicinity of the permeable planar component; making a hydraulic connection between the permeable planar component and a pump; permitting the sealant to cure and thereby provide both mechanical and hydraulic confinement to the permeable planar component; and pumping a fluid from the pump into the permeable planar component to internally pressurize the permeable planar component to initiate a fracture in the formation, the fracture being disposed in the same orientation as the permeable planar component.

Swanson, David E. (West St. Paul, MN); Daly, Daniel W. (Crystal, MN)

1994-01-01

17

Regulation of Hydraulic Fracturing in California  

E-print Network

APRIL 2013 Regulation of Hydraulic Fracturing in California: A WAsteWAteR And WAteR QuAlity Pe | Regulation of Hydraulic Fracturing in California Wheeler Institute for Water Law & Policy Center for Law #12;Regulation of Hydraulic Fracturing in California | 3Berkeley law | wheeler InstItute for water law

Kammen, Daniel M.

18

Hydraulic Fracture: multiscale processes and moving  

E-print Network

Hydraulic Fracture: multiscale processes and moving interfaces Anthony Peirce Department Mitchell (UBC) · Ed Siebrits (SLB, Houston) #12;2 Outline · What is a hydraulic fracture? · Scaling Fluid Proppant #12;6 An actual hydraulic fracture #12;7 HF experiment (Jeffrey et al CSIRO) #12;8 1D

Peirce, Anthony

19

Hydraulic Fracture: multiscale processes and moving  

E-print Network

Hydraulic Fracture: multiscale processes and moving interfaces Anthony Peirce Department Siebrits (SLB, Houston) #12;2 Outline · What is a hydraulic fracture? · Mathematical models of hydraulic fracture · Scaling and special solutions for 1-2D models · Numerical modeling for 2-3D problems

Peirce, Anthony

20

Hydraulic Fracturing in Michigan Integrated Assessment  

E-print Network

Hydraulic Fracturing in Michigan Integrated Assessment #12;Agenda · Welcome and introduction and timeline · Panel presentation and discussion · Facilitated Q & A · Closing remarks #12;Hydraulic Fracturing · Leverages resources IA BENEFITS Benefits of Integrated Assessment #12;Key Points: · Hydraulic Fracturing (HF

Kamat, Vineet R.

21

Characterization of the hydraulic properties of fractures in chalk.  

PubMed

The fracture systems intersecting Eocene chalk formations in the Negev desert, Israel, and their hydraulic properties were characterized using a variety of geologic and hydrologic techniques. These included identification of the prevailing directions of fracture systems in outcrops, in cores retrieved from inclined coreholes, in coreholes using video logs, and in trenches. The orientation and inclination of these fracture systems were determined, and evidence of ground water flow on the fracture surfaces was described and ranked. Their hydraulic conductivity was determined through slug and pumping tests performed at discrete intervals. Temperature, electrical conductivity, caliper, gamma and heat-pulse logs were conducted in the same coreholes. The results from the logs, tests, and core descriptions were compared to identify reliable and cost-effective tools for investigating the hydraulic characteristics of fracture systems. We concluded that in the study area: (1) fracture mapping in outcrops and coreholes (including downhole video and caliper logs) must be supplemented by hydraulic testing of the mapped fracture sets in the coreholes; (2) inclined coreholes provide information regarding the orientation of the hydraulically active fracture systems that cannot be obtained from vertical boreholes; (3) hydraulic testing of unpacked holes provides a reasonable estimate of the maximum hydraulic conductivity; and (4) the hydraulic conductivity distribution with depth is log normal and all significant ground water flow takes place within the upper 25 m. PMID:12873016

Nativ, Ronit; Adar, Eilon; Assaf, Lior; Nygaard, Erik

2003-01-01

22

Monitoring hydraulic fracture growth: Laboratory experiments  

SciTech Connect

The authors carry out small-scale hydraulic fracture experiments to investigate the physics of hydraulic fracturing. The laboratory experiments are combined with time-lapse ultrasonic measurements with active sources using both compressional and shear-wave transducers. For the time-lapse measurements they focus on ultrasonic measurement changes during fracture growth. As a consequence they can detect the hydraulic fracture and characterize its shape and geometry during growth. Hence, this paper deals with fracture characterization using time-lapse acoustic data. Hydraulic fracturing is used in the oil and gas industry to stimulate reservoir production.

Groenenboom, J.; Dam, D.B. van

2000-04-01

23

Hydraulic fracture optimization using hydraulic fracture and reservoir modeling in the Piceance Basin, Colorado.  

E-print Network

??Hydraulic fracturing is an important stimulation method for producing unconventional gas reserves. Natural fractures are present in many low-permeability gas environments and often provide important… (more)

Reynolds, Harris Allen

2012-01-01

24

Acoustic Character Of Hydraulic Fractures In Granite  

E-print Network

Hydraulic fractures in homogeneous granitic rocks were logged with conventional acoustic-transit-time, acoustic-waveform, and acoustic-televiewer logging systems. Fractured intervals ranged in depth from 45 to 570m. and ...

Paillet, Frederick I.

1983-01-01

25

Simulation of Hydraulic Fractures and their Interactions with Natural Fractures  

E-print Network

on stimulated volume and fracture network complexity. This thesis presents a boundary element and finite difference based method for modeling this interaction during hydraulic fracturing process. In addition, an improved boundary element model is developed...

Sesetty, Varahanaresh

2012-10-19

26

A PKN Hydraulic Fracture Model Study and Formation Permeability Determination  

E-print Network

and unconventional hydraulic fracturing operations, fracturing during water-flooding of petroleum reservoirs, shale gas, and injection/extraction operation in a geothermal reservoir. Designing a hydraulic fracturing job requires an understanding of fracture growth...

Xiang, Jing

2012-02-14

27

DEMONSTRATION BULLETIN: HYDRAULIC FRACTURING OF CONTAMINATED SOIL  

EPA Science Inventory

Hydraulic fracturing is a physical process that creates fractures in silty clay soil to enhance its permeability. The technology, developed by the Risk Reduction Engineering Laboratory (RREL) and the University of Cincinnati, creates sand-filled horizontal fractures up to 1 in. i...

28

The crack tip region in hydraulic fracturing  

Microsoft Academic Search

We present analytical tip region solutions for fracture width and pressure when a power law fluid drives a plane strain fracture in an impermeable linear elastic solid. Our main result is an intermediate asymptotic solution in which the tip region stress is dominated by a singularity which is particular to the hydraulic fracturing problem. Moreover this singularity is weaker than

J. Desroches; E. Detournay; B. Lenoach; P. Papanastasiou; J. R. A. Pearson; M. Thiercelin; A. Cheng

1994-01-01

29

Hydraulic Fracturing and the Environment  

NASA Astrophysics Data System (ADS)

In this presentation, we highlight two key environmental concerns of hydraulic fracturing (HF), namely induced seismicity and groundwater contamination (GC). We examine the induced seismicity (IS) associated with different subsurface fluid injection and production (SFIP) operations and the key operational parameters of SFIP impacting it. In addition we review the key potential sources for possible water contamination. Both in the case of IS and GC we propose modeling and data analysis methods to quantify the risk factors to be used for monitoring and risk reduction. SFIP include presents a risk in hydraulic fracturing, waste water injection, enhanced oil recovery as well as geothermal energy operations. Although a recent report (NRC 2012) documents that HF is not responsible for most of the induced seismicities, we primarily focus on HF here. We look into vaious operational parameters such as volume and rate of water injection, the direction of the well versus the natural fracture network, the depth of the target and the local stress field and fault system, as well as other geological features. The latter would determine the potential for triggering tectonic related events by small induced seismicity events. We provide the building blocks for IS risk assessment and monitoring. The system we propose will involve adequate layers of complexity based on mapped seismic attributes as well as results from ANN and probabilistic predictive modeling workflows. This leads to a set of guidelines which further defines 'safe operating conditions' and 'safe operating zones' which will be a valuable reference for future SFIP operations. We also illustrate how HF can lead to groundwater aquifer contamination. The source of aquifer contamination can be the hydrocarbon gas or the chemicals used in the injected liquid in the formation. We explore possible pathways of contamination within and discuss the likelihood of contamination from each source. Many of the chemical compounds used in HF fluids are carcinogenic and may pose risk to humans. In addition, recovered HF fluids can be contaminated. We illustrate how different pathways can lead to the risk of aquifer contamination and consequently, risk to human health.

Ayatollahy Tafti, T.; Aminzadeh, F.; Jafarpour, B.; de Barros, F.

2013-12-01

30

Reply to Davies: Hydraulic fracturing remains a possible mechanism for  

E-print Network

LETTER Reply to Davies: Hydraulic fracturing remains a possible mechanism for observed methane mechanisms were leaky gas well casings and the possibility that hydraulic fracturing might generate new- knowledged the possibility of hydraulic fracturing playing a role. Is it possible that hydraulic fracturing

Jackson, Robert B.

31

In situ stress estimates from hydraulic fracturing and direct observation of crack orientation  

Microsoft Academic Search

Estimates of in situ stress in G Tunnel Rainier Mesa, Nevada Test Site, have been obtained with hydraulic fracturing techniques. This work represents a nontraditional use of hydraulic fracturing in that it was performed primarily in horizontal boreholes drilled into the formation from access drifts tunneled into the mesa rather than the usual operation performed at depth in vertical boreholes

William E. Warren; Carl W. Smith

1985-01-01

32

Gas condensate damage in hydraulically fractured wells  

E-print Network

GAS CONDENSATE DAMAGE IN HYDRAULICALLY FRACTURED WELLS A Thesis by REZA ROSTAMI RAVARI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 2004 Major Subject: Petroleum Engineering GAS CONDENSATE DAMAGE IN HYDRAULICALLY FRACTURED WELLS A Thesis by REZA ROSTAMI RAVARI Submitted to Texas A&M University in partial...

Reza, Rostami Ravari

2004-11-15

33

Self-potential observations during hydraulic fracturing  

SciTech Connect

The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of -200 mV/MPa. However for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of micro-cracks, and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of {approx}35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing.

Moore, Jeffrey R.; Glaser, Steven D.

2007-09-13

34

Hydraulic Fracturing Mineback Experiment in Complex Media  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing (or "fracking") for the recovery of gas and liquids from tight shale formations has gained much attention. This operation which involves horizontal well drilling and massive hydraulic fracturing has been developed over the last decade to produce fluids from extremely low permeability mudstone and siltstone rocks with high organic content. Nearly thirteen thousand wells and about one hundred and fifty thousand stages within the wells were fractured in the US in 2011. This operation has proven to be successful, causing hundreds of billions of dollars to be invested and has produced an abundance of natural gas and is making billions of barrels of hydrocarbon liquids available for the US. But, even with this commercial success, relatively little is clearly known about the complexity--or lack of complexity--of the hydraulic fracture, the extent that the newly created surface area contacts the high Reservoir Quality rock, nor the connectivity and conductivity of the hydraulic fractures created. To better understand this phenomena in order to improve efficiency, a large-scale mine-back experiment is progressing. The mine-back experiment is a full-scale hydraulic fracture carried out in a well-characterized environment, with comprehensive instrumentation deployed to measure fracture growth. A tight shale mudstone rock geologic setting is selected, near the edge of a formation where one to two thousand feet difference in elevation occurs. From the top of the formation, drilling, well logging, and hydraulic fracture pumping will occur. From the bottom of the formation a horizontal tunnel will be mined using conventional mining techniques into the rock formation towards the drilled well. Certain instrumentation will be located within this tunnel for observations during the hydraulic fracturing. After the hydraulic fracturing, the tunnel will be extended toward the well, with careful mapping of the created hydraulic fracture. Fracturing fluid will be traceable, as will injected proppant, in order to demarcate in-situ fracture paths and fluid and proppant progression. This underground experiment is referred to as a "mine-back experiment". Several mine-back experiments have been conducted in the past, and have demonstrated complex, diffuse fracture systems in coals and bundled fracture systems in some sandstones. No mine-back experiment has been conducted in the tight shales; but, economics and environmental considerations dictate that more definitive measurements will be extremely helpful to establish fracture growth patterns and to validate monitoring methods such as micro-seismic measurements. This presentation discusses the mine-back experiment and presents details of geologic setting, hydraulic fracturing, and the excavation required before and after the hydraulic fracture. The mine-back experiment will provide ground-truth assessment of hydraulic fracturing, geologic forecasting, micro-seismicity, and other information.

Green, S. J.; McLennan, J. D.

2012-12-01

35

Microseismic logging: A new hydraulic fracture diagnostic method  

SciTech Connect

Hydraulic fracture treatments and fluid injections into fractured wells induce cloud of microseismic sources in the fractured zone. This induced seismicity can last for hours after pumping and pervades the fracture. The source-size population distribution ranges from a countable (50 to 500) number of large, individually distinguishable event to a din of background events. Each source radiates wave motion, which can be recorded only in and near the fracture. A new method uses these motion data, recorded in the cased treatment well, to determine the fracture height and azimuth. The height is found by delineating the location and vertical extent of a spatial anomaly in the background-motion data. The azimuth is derived from the particle-motion polarization of the largest events of the microseismic event population. This paper describes the method, exemplary data sets, theory, and simulations that substantiate this method.

Mahrer, K.D. (Teledyne Geotech, Alexandria, VA (United States))

1993-03-01

36

Hydraulic Fracturing Slurry Transport in Horizontal Pipes  

Microsoft Academic Search

Horizontal-well activity has increased throughout the industry in the past few years. To design a successful hydraulic fracturing treatment for horizontal wells, accurate information on the transport properties of slurry in horizontal pipe is required. Limited information exists that can be used to estimate critical deposition and resuspension velocities when proppants are transported in horizontal wells with non-Newtonian fracturing gels.

Subhash Shah; David Lord

1990-01-01

37

The influence of plasticity in hydraulic fracturing  

Microsoft Academic Search

This paper examines the influence of plasticity in hydraulic fracturing. Fluid flow in the fracture is modelled by lubrication theory. Rock deformation is modelled by the Mohr–Coulomb flow theory of plasticity and the propagation criterion is based on the softening behaviour of rocks. The coupled, nonlinear problem is solved by a combined finite difference–finite element scheme. The results show that

Panos Papanastasiou

1997-01-01

38

Laboratory Hydraulic Fracture Characterization Using Acoustic Emission  

NASA Astrophysics Data System (ADS)

For many years Acoustic Emission (AE) testing has aided in the understanding of fracture initiation and propagation in geologic materials. AEs occur when a material emits elastic waves caused by the sudden occurrence of fractures or frictional sliding along discontinuous surfaces and grain boundaries. One important application of AE is the monitoring of hydraulic fracturing of underground formations to create functional reservoirs at sites where the permeability of the rock is too limited to allow for cost effective fluid extraction. However, several challenges remain in the use of AE to locate and characterize fractures that are created hydraulically. Chief among these challenges is the often large scatter of the AE data that are generated during the fracturing process and the difficulty of interpreting the AE data so that hydraulic fractures can be reliably characterized. To improve the understanding of the link between AE and hydraulic fracturing, laboratory scale model testing of hydraulic fracturing were performed using a cubical true triaxial device. This device consist of a loading frame capable of loading a 30x30x30 cm3 rock sample with three independent principal stresses up to 13 MPa while simultaneously providing heating up to 180 degrees C. Several laboratory scale hydraulic fracture stimulation treatments were performed on granite and rock analogue fabricated using medium strength concrete. A six sensor acoustic emission (AE) array, using wideband piezoelectric transducers, is employed to monitor the fracturing process. AE monitoring of laboratory hydraulic fracturing experiments showed multiple phenomena including winged fracture growth from a borehole, cross-field well communication, fracture reorientation, borehole casing failure and much more. AE data analysis consisted of event source location determination, fracture surface generation and validation, source mechanism determination, and determining the overall effectiveness of the induced fracture network. Source mechanisms were identified using a simplified moment tensor analysis which utilizes the first AE arrival characteristics to determine crack type classifications from a unified decomposition of eigenvalues. The AE event source mechanism locations were plotted to determine if spatial relationships exist and to delineate tensile, shear and mixed mode fractures throughout the testing. Based on the classification of the AE data and the moment tensor analysis, an algorithm was developed to predict the location, extent and geometry of the induced fracture. Differing factors were investigated on how they affect the distribution of tensile and shear fractures including viscosity of fracturing fluid, brittleness of source material, homogeneity of source material, presence of natural fractures and stress conditions. Post-test sample coring and slicing were performed to validate the AE event source locations and the fracture characterization algorithm. Fracture and reservoir condition data from the cores and slices were plotted with the AE event source mechanism locations to validate hypotheses regarding spatial relationships of source mechanisms and test conditions. It was shown that the proposed algorithm can reliably delineate hydraulic fracture characteristics in terms of location, extent and geometry.

Gutierrez, M.

2013-05-01

39

Distribution, Origin, and Hydraulic Influence of Fractures in a Clay-rich Glacial Deposit  

Microsoft Academic Search

In the unconsolidated clay-rich glacial deposits underlying a site in southwestern Ontario, fractures and root casts greatly influence hydraulic conductivity and groundwater flow. The fractures are predominantly vertical and have visible oxidation staining from surface to a depth of 6 m. Root casts commonly occur along fracture surfaces in the upper 3?m, but can also occur as holes in apparently

Larry McKay; J. Fredericia

1995-01-01

40

Coupling schemes for modeling hydraulic fracture propagation using the XFEM  

E-print Network

Coupling schemes for modeling hydraulic fracture propagation using the XFEM Elizaveta Gordeliy of hydraulic fractures in an elastic medium. With appropriate enrichment, the XFEM resolves the Neumann(h) accuracy. For hydraulic fracture problems with a lag separating the uid front from the fracture front, we

Peirce, Anthony

41

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS?  

E-print Network

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS? Ania Morvannoua , Nicolas-equilibrium model, preferential flow path, vertical flow constructed wetlands INTRODUCTION Constructed wetlands (CWs

Paris-Sud XI, Université de

42

Effectiveness of microseismic monitoring for optimizing hydraulic fracturing in California  

E-print Network

Hydraulic fracturing has fundamentally changed the oil and gas industry in the past 10 years. Bakersfield, California provides a unique case study because steam injection, a type of hydraulic fracturing, has been used there ...

Alampi, Ann M

2014-01-01

43

Hydraulic conductivity of rock fractures  

Microsoft Academic Search

The flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of fluid mechanics. The derivation of the ‘cubic law’ is given as the solution to the Navier-Stokes equations for flow between smooth, parallel plates - the only fracture geometry that is amenable to exact treatment. The various geometric and kinematic conditions that are necessary

Robert W. Zimmerman; Gudmundur S. Bodvarsson

1996-01-01

44

HYDRAULIC STIMULATION OF NATURAL FRACTURES AS REVEALED BY INDUCED MICROEARTHQUAKES,  

E-print Network

-1- HYDRAULIC STIMULATION OF NATURAL FRACTURES AS REVEALED BY INDUCED MICROEARTHQUAKES, CARTHAGE, December, 2001 Manuscript # 01066 LAUR# 01-1204 #12;Hydraulic Stimulation of Natural Fractures -2- ABSTRACT We have produced a high-resolution microseismic image of a hydraulic fracture stimulation

45

RPSEA UNCONVENTIONAL GAS CONFERENCE 2012: Geology, the Environment, Hydraulic Fracturing  

E-print Network

RPSEA UNCONVENTIONAL GAS CONFERENCE 2012: Geology, the Environment, Hydraulic Fracturing April 17 Fracturing Experiment ­ Gas Technology Institute and Range Resources 3:15 p.m. Marcellus Shale Hydraulic of Economic Geology 4 p.m. Marcellus Hydraulic Fracturing Research Results - Jordan Ciezobka, Gas Technology

Yener, Aylin

46

Modeling Turbulent Hydraulic Fracture Near a Free Surface  

E-print Network

Modeling Turbulent Hydraulic Fracture Near a Free Surface Victor C. Tsai Seismological Laboratory consider a hydraulic fracture problem in which the crack grows parallel to a free surface, subject to fully components. wall Wall shear stress. ^· Non-dimensionalized ·. 1 Introduction Hydraulic fracture has been

47

Role of seepage forces on hydraulic fracturing and failure patterns  

E-print Network

Role of seepage forces on hydraulic fracturing and failure patterns Alexander Rozhko Thesis September 2007 #12;ii Role of seepage forces on hydraulic fracturing and failure patterns Abstract. The mechanical role of seepage forces on hydraulic fracturing and failure patterns was studied both

Paris-Sud XI, Université de

48

Modeling Turbulent Hydraulic Fracture Near a Free Surface  

E-print Network

Modeling Turbulent Hydraulic Fracture Near a Free Surface Victor C. Tsai Seismological Laboratory consider a hydraulic fracture problem in which the crack grows parallel to a free surface, subject to fully components. ^· Non-dimensionalized ·. 1 Introduction Hydraulic fracture has been studied for many years

49

Gas condensate damage in hydraulically fractured wells  

E-print Network

This project is a research into the effect of gas condensate damage in hydraulically fractured wells. It is the result of a problem encountered in producing a low permeability formation from a well in South Texas owned by the El Paso Production...

Adeyeye, Adedeji Ayoola

2004-09-30

50

Hydraulic fractur ing--also called hy  

E-print Network

.S. since development of gas extraction from the Marcellus Shale has become increasingly viableHydraulic fractur ing--also called hy drofracking or frack ing--is a process where large volumes Schematic diagram of underground natural gas sources, including gasrich shale. Image: original, U

Goodman, Robert M.

51

Linking earthquakes and hydraulic fracturing operations  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing, also known as fracking, to extract oil and gas from rock, has been a controversial but increasingly common practice; some studies have linked it to groundwater contamination and induced earthquakes. Scientists discussed several studies on the connection between fracking and earthquakes at the AGU Fall Meeting in San Francisco in December.

Balcerak, Ernie

2013-01-01

52

An analytical model for hydraulic fracturing in shallow bedrock formations.  

PubMed

A theoretical method is proposed to estimate post-fracturing fracture size and transmissivity, and as a test of the methodology, data collected from two wells were used for verification. This method can be employed before hydrofracturing in order to obtain estimates of the potential hydraulic benefits of hydraulic fracturing. Five different pumping test analysis methods were used to evaluate the well hydraulic data. The most effective methods were the Papadopulos-Cooper model (1967), which includes wellbore storage effects, and the Gringarten-Ramey model (1974), known as the single horizontal fracture model. The hydraulic parameters resulting from fitting these models to the field data revealed that as a result of hydraulic fracturing, the transmissivity increased more than 46 times in one well and increased 285 times in the other well. The model developed by dos Santos (2008), which considers horizontal radial fracture propagation from the hydraulically fractured well, was used to estimate potential fracture geometry after hydrofracturing. For the two studied wells, their fractures could have propagated to distances of almost 175 m or more and developed maximum apertures of about 2.20 mm and hydraulic apertures close to 0.30 mm. Fracturing at this site appears to have expanded and propagated existing fractures and not created new fractures. Hydraulic apertures calculated from pumping test analyses closely matched the results obtained from the hydraulic fracturing model. As a result of this model, post-fracturing geometry and resulting post-fracturing well yield can be estimated before the actual hydrofracturing. PMID:20572875

dos Santos, José Sérgio; Ballestero, Thomas Paul; Pitombeira, Ernesto da Silva

2011-01-01

53

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

E-print Network

Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks Mingjie Chen Keywords: Hydraulic fracturing Fractal dimension Surrogate model Optimization Global sensitivity a b s t r a c t Hydraulic fracturing has been used widely to stimulate production of oil, natural gas

Lu, Zhiming

54

Uncertainty Analysis of Simulated Hydraulic Fracturing  

NASA Astrophysics Data System (ADS)

Artificial hydraulic fracturing is being used widely to stimulate production of oil, natural gas, and geothermal reservoirs with low natural permeability. Optimization of field design and operation is limited by the incomplete characterization of the reservoir, as well as the complexity of hydrological and geomechanical processes that control the fracturing. Thus, there are a variety of uncertainties associated with the pre-existing fracture distribution, rock mechanics, and hydraulic-fracture engineering that require evaluation of their impact on the optimized design. In this study, a multiple-stage scheme was employed to evaluate the uncertainty. We first define the ranges and distributions of 11 input parameters that characterize the natural fracture topology, in situ stress, geomechanical behavior of the rock matrix and joint interfaces, and pumping operation, to cover a wide spectrum of potential conditions expected for a natural reservoir. These parameters were then sampled 1,000 times in an 11-dimensional parameter space constrained by the specified ranges using the Latin-hypercube method. These 1,000 parameter sets were fed into the fracture simulators, and the outputs were used to construct three designed objective functions, i.e. fracture density, opened fracture length and area density. Using PSUADE, three response surfaces (11-dimensional) of the objective functions were developed and global sensitivity was analyzed to identify the most sensitive parameters for the objective functions representing fracture connectivity, which are critical for sweep efficiency of the recovery process. The second-stage high resolution response surfaces were constructed with dimension reduced to the number of the most sensitive parameters. An additional response surface with respect to the objective function of the fractal dimension for fracture distributions was constructed in this stage. Based on these response surfaces, comprehensive uncertainty analyses were conducted among input parameters and objective functions. In addition, reduced-order emulation models resulting from this analysis can be used for optimal control of hydraulic fracturing. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Chen, M.; Sun, Y.; Fu, P.; Carrigan, C. R.; Lu, Z.

2012-12-01

55

Fracturing Demonstration using a Hydraulic Press  

NSDL National Science Digital Library

To prepare for the demonstration students are assigned homework problems dealing with brittle deformation in which they must plot Mohr diagrams and determine shear plane orientations and Coulomb coefficients. In class we examine an undeformed core of Yazoo clay (Eocene) taken from a test site on campus. The core is then uniaxially compressed using a hydraulic press. The students are then asked to observe and describe the development of shear fractures (including conjugate shear surfaces) and measure their orientations. In addition, they are asked to speculate on the development of extension fractures that develop during unloading. The fracture data are then used to estimate the Coulomb coefficient for the Yazoo clay sample and comparisons are made to values obtained from samples of differing lithologies. We wrap up with a class discussion summarizing observations from the fracture demonstration.

James B. Harris

56

Economic Recovery of Oil Trapped at Fan Margins Using High Angle Wells and Multiple Hydraulic Fractures  

SciTech Connect

The distal fan margin in the northeast portion of the Yowlumne field contains significant reserves but is not economical to develop using vertical wells. Numerous interbedded shales and deteriorating rock properties limit producibility. In addition, extreme depths (13,000 ft) present a challenging environment for hydraulic fracturing and artificial lift. Lastly, a mature waterflood increases risk because of the uncertainty with size and location of flood fronts. This project attempts to demonstrate the effectiveness of exploiting the distal fan margin of this slope-basin clastic reservoir through the use of a high-angle well completed with multiple hydraulic-fracture treatments. The combination of a high-angle (or horizontal) well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. The equivalent production rate and reserves of three vertical wells are anticipated at one-half to two-thirds the cost.

Mike L. Laue

1997-05-30

57

Self-potential observations during hydraulic fracturing  

Microsoft Academic Search

The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of ?200 mV\\/MPa. However, for pressure drops >2

Jeffrey R. Moore; Steven D. Glaser

2007-01-01

58

Self-potential observations during hydraulic fracturing  

Microsoft Academic Search

The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of -200 mV\\/MPa. However for pressure drops >2

Jeffrey R. Moore; Steven D. Glaser

2007-01-01

59

Marcellus Shale Drilling and Hydraulic Fracturing; Technicalities and  

E-print Network

Marcellus Shale Drilling and Hydraulic Fracturing; Technicalities and Controversies Kyle J Ferrar;Stimulating by Hydraulic Fracturing · Perforating ­ "Perf Gun" ­ Multiple Stages ­ 1,000 meter sections Pipe · Air Rotary Drilling Rig · Hydraulic Rotary Drilling Rig ­ Barite/Bentonite infused drilling muds

Jiang, Huiqiang

60

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions  

E-print Network

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions SANUM Conference (UMN) Eduard Siebrits (SLB) #12;2 Outline · Examples of hydraulic fractures · Governing equations well stimulation Fracturing Fluid Proppant #12;5 Quarries #12;6 Magma flow Tarkastad #12;7 Model EQ 1

Peirce, Anthony

61

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions  

E-print Network

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions CSIRO CSS TCP Detournay (UMN) Eduard Siebrits (SLB) #12;2 Outline · Examples of hydraulic fractures · Governing equations well stimulation Fracturing Fluid Proppant #12;5 Quarries #12;6 Magma flow Tarkastad #12;7 Model EQ 1

Peirce, Anthony

62

Potential contaminant pathways from hydraulically fractured shale to aquifers.  

PubMed

Hydraulic fracturing of deep shale beds to develop natural gas has caused concern regarding the potential for various forms of water pollution. Two potential pathways-advective transport through bulk media and preferential flow through fractures-could allow the transport of contaminants from the fractured shale to aquifers. There is substantial geologic evidence that natural vertical flow drives contaminants, mostly brine, to near the surface from deep evaporite sources. Interpretative modeling shows that advective transport could require up to tens of thousands of years to move contaminants to the surface, but also that fracking the shale could reduce that transport time to tens or hundreds of years. Conductive faults or fracture zones, as found throughout the Marcellus shale region, could reduce the travel time further. Injection of up to 15,000,000 L of fluid into the shale generates high pressure at the well, which decreases with distance from the well and with time after injection as the fluid advects through the shale. The advection displaces native fluids, mostly brine, and fractures the bulk media widening existing fractures. Simulated pressure returns to pre-injection levels in about 300 d. The overall system requires from 3 to 6 years to reach a new equilibrium reflecting the significant changes caused by fracking the shale, which could allow advective transport to aquifers in less than 10 years. The rapid expansion of hydraulic fracturing requires that monitoring systems be employed to track the movement of contaminants and that gas wells have a reasonable offset from faults. PMID:22509908

Myers, Tom

2012-01-01

63

Electric-hydraulic conductivity correlation in fractured crystalline bedrock: Central Landfill, Rhode Island, USA  

NASA Astrophysics Data System (ADS)

Remote sensing and geoelectrical methods were used to find water-bearing fractures in the Scituate granite under the Central Landfill of Rhode Island. These studies were necessary to evaluate the integrity of the sanitary landfill and for planning safe landfill extensions. The most useful results were obtained with fracture trace analysis using Landsat and SLAR imagery in combination with ground-based resistivity measurements using Schlumberger vertical electrical soundings based on the assumption of horizontally layered strata. Test borings and packer tests confirmed, in the presence of a lineament and low bedrock resistivity, the probable existence of high bedrock fracture density and high average hydraulic conductivity. However, not every lineament was found to be associated with high fracture density and high hydraulic conductivity. Lineaments alone are not a reliable basis for characterising a landfill site as being affected by fractured bedrock. Horizontal fractures were found in borings located away from lineaments. High values of hydraulic conductivity were correlated with low bedrock resistivities. Bedrock resistivities between 60 and 700 ? m were associated with average hydraulic conductivities between 4 and 60 cm/day. In some cases very low resistivities were confined to the upper part of the bedrock where the hydraulic conductivity was very large. These types of fractures apparently become narrower in aperture with depth. Bedrock zones having resistivities greater than 1000 ? m showed, without exception, no flow to the test wells. Plots of bedrock resistivity versus the average hydraulic conductivity indicate that the resistivity decreases with increasing hydraulic conductivity. This relationship is inverse to that found in most unconsolidated sediments and is useful for estimating the hydraulic conductivity in groundwater surveys in fractured bedrock. In appropriate settings such as the Central Landfill site in New England, this electric-hydraulic correlation relationship, supplemented by lineament trace analysis, can be used effectively to estimate the hydraulic conductivity in bedrock from only a limited number of resistivity depth soundings and test wells.

Frohlich, Reinhard K.; Fisher, John J.; Summerly, E.

1996-10-01

64

Experimental investigation of geomechanical aspects of hydraulic fracturing unconventional formations.  

E-print Network

??Understanding the mechanisms that govern hydraulic fracturing applications in unconventional formations, such as gas-bearing shales, is of increasing interest to the petroleum upstream industry. Among… (more)

Alabbad, Emad Abbad

2014-01-01

65

Hydraulic Fracture Monitoring: A Jonah Field Case Study  

E-print Network

Hydraulic fracturing involves the injection of a fluid to fracture oil and gas reservoirs, and thus increase their permeability. The process creates numerous microseismic events, which can be used to monitor subsurface ...

Seher, T.

2011-01-01

66

Fracture characterization from vertical seismic profiling data  

NASA Astrophysics Data System (ADS)

In vertical seismic profiling (VSP) data, large-amplitude borehole Stoneley waves are observed at depths where fractures intersect the borehole. We present a model which predicts the amplitudes of these Stoneley waves as a function of certain parameters of the fractures, namely, the fracture aperture (width), the orientation, and the degree of stiffness and roughness of the fracture. The proposed mechanism for the generation of these borehole Stoneley waves is coupling of a guided mode, induced in the fracture by an incident plane wave (typically a P wave), to the borehole. The model expresses the borehole Stoneley wave amplitude, normalized by the amplitude of the direct P wave, as a function of frequency, in terms of the fracture parameters. The model is used as the basis for an inversion scheme, employing a nonlinear least squares algorithm to estimate the fracture parameters. The inversion is then applied to VSP data where borehole Stoneley waves are observed at depths where fractures are known to intersect the borehole. The results of the inversion indicate that the aperture and vertical component of the orientation (i.e., dip) of the fracture can be accurately estimated but the horizontal component of the orientation (i.e., strike) is not well resolved.

Cicerone, Robert D.; Toksoz, M. Nafi

1995-03-01

67

Hydraulic Fracturing and Drinking Water Resources: Update on EPA Hydraulic Fracturing Study  

EPA Science Inventory

Natural gas plays a key role in our nation's energy future and the process known as hydraulic fracturing (HF) is one way of accessing that resource. Over the past few years, several key technical, economic, and energy developments have spurred increased use of HF for gas extracti...

68

Limited entry extended to massive hydraulic fracturing  

SciTech Connect

Limited entry techniques have recently been applied in massive hydraulic fracturing (MHF) of the Niobrara/Codell intervals of the Denver-Julesberg basin. Erratic surface treating pressure behavior and partial-to-complete well screenouts were frequently encountered during simultaneous treatment of these zones. This may be indicative of a lack of control of interzonal treatment fluid placement. There are field-proved solutions to this problem of interzonal fluid entry control during limited entry MHF. This first of two article examines the downhole interactions that occur.

Cramer, D.D.

1987-12-14

69

Seismic studies of a massive hydraulic fracturing experiment  

SciTech Connect

During a massive hydraulic fracturing experiment carried out at Fenton Hill, New Mexico, 850 microearthquakes, ranging in magnitudes from -3 to 0, were located reliably using arrival times recorded at a set of 5 downhole geophone stations. A subset of these events were located using an upgraded hodogram technique. The seismicity defines a tabular zone with horizontal extent of 900 m, vertical extent of 800 m, and thickness of 150 m. This zone strikes N340/sup 0/E, and dips 75/sup 0/ to the east; its position indicates that no hydraulic connection between the two predrilled wells could be achieved by the fracturing. The distribution of locations obtained from arrival times shows good agreement with those derived from hodograms. Well constrained fault plane solutions were determined for 26 of the larger microearthquakes observed at a surface seismic net. Most solutions display one nearly vertical nodal plane that strikes close to N - S, and a T axis that trends roughly E - W, in agreement with regional indicators of the least principal stress direction. 9 refs., 6 figs.

House, L.; Keppler, H.; Kaieda, H.

1985-01-01

70

Vertical root fractures and their management  

PubMed Central

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

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

2014-01-01

71

Analytical Modeling of Shale Hydraulic Fracturing and Gas Production  

NASA Astrophysics Data System (ADS)

Shale gas is abundant all over the world. Due to its extremely low permeability, extensive stimulation of a shale reservoir is always required for its economic production. Hydraulic fracturing has been the primary method of shale reservoir stimulation. Consequently the design and optimization of a hydraulic fracturing treatment plays a vital role insuring job success and economic production. Due to the many variables involved and the lack of a simple yet robust tool based on fundamental physics, horizontal well placement and fracturing job designs have to certain degree been a guessing game built on previous trial and error experience. This paper presents a method for hydraulic fracturing design and optimization in these environments. The growth of a complex hydraulic fracture network (HFN) during a fracturing job is equivalently represented by a wiremesh fracturing model (WFM) constructed on the basis of fracture mechanics and mass balance. The model also simulates proppant transport and placement during HFN growth. Results of WFM simulations can then be used as the input into a wiremesh production model (WPM) constructed based on WFM. WPM represents gas flow through the wiremesh HFN by an elliptic flow and the flow of gas in shale matrix by a novel analytical solution accounting for contributions from both free and adsorbed gases stored in the pore space. WPM simulation is validated by testing against numerical simulations using a commercially available reservoir production simulator. Due to the analytical nature of WFM and WPM, both hydraulic fracturing and gas production simulations run very fast on a regular personal computer and are suitable for hydraulic fracturing job design and optimization. A case study is presented to demonstrate how a non-optimized hydraulic fracturing job might have been optimized using WFM and WPM simulations.Fig. 1. Ellipsoidal representation of (a) stimulated reservoir and (b) hydraulic fracture network created by hydraulic fracturing treatment. Fig. 2. Gas flow represented by (a) elliptical flow through fracture network and (b) linear flow within reservoir matrix.

Xu, W.

2012-12-01

72

Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.  

PubMed

Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level. PMID:23552653

Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

2013-01-01

73

Analysis of the Influence of a Natural Fracture Network on Hydraulic Fracture Propagation in Carbonate Formations  

NASA Astrophysics Data System (ADS)

A new experimental model has been designed to simulate the influence of a natural fracture network on the propagation geometry of hydraulic fractures in naturally fractured formations using a tri-axial fracturing system. In this model, a parallel and symmetrical pre-fracture network was created by placing cement plates in a cubic mold and filling the mold with additional cement to create the final testing block. The surface of the plates will thus be weakly cemented and form pre-fractures. The dimension and direction of the pre-fractures can be controlled using the plates. The experiments showed that the horizontal differential stress and the angle between the maximum horizontal principal in situ stress and the pre-fracture are the dominating factors for the initiation and propagation of hydraulic fractures. For and or and , the direction of the initiation and propagation of the hydraulic fractures are consistent with or deviate from the normal direction of the pre-fracture. When the hydraulic fractures approach the pre-fractures, the direction of the hydraulic fracture propagation will be consistent with the normal direction of the pre-fracture. Otherwise, the hydraulic fracture will deflect and perpendicularly cross the parallel and symmetric pre-fracture network. For and , and or and , before the hydraulic fracture and the pre-fractures intersect, the direction of the hydraulic fracture propagation remains unchanged, and the pre-fractures open or dilate when the hydraulic fracture propagates to the intersection point, forming a complicated hydraulic fracture network with the propagation region of the overall hydraulic fracture network taking the shape of an ellipse. In this condition, the complexity level of the hydraulic fracture is controlled by the net pressure, the compressive normal stress acting on the pre-fractures, the shearing strength and the cohesion strength of the planes of weakness. The conclusions of this research are inconsistent with the formulation of the approach angle that has been widely accepted by previous studies. The principle of hydraulic fracture propagation is that it follows the least resistance, the most preferential propagation, and the shortest propagation path.

Liu, Zhiyuan; Chen, Mian; Zhang, Guangqing

2014-03-01

74

78 FR 55253 - Notification of Public Teleconference of the Hydraulic Fracturing Research Advisory Panel  

Federal Register 2010, 2011, 2012, 2013, 2014

...Notification of Public Teleconference of the Hydraulic Fracturing Research Advisory Panel AGENCY...announces a public teleconference of the Hydraulic Fracturing Research Advisory Panel to...new and emerging information related to hydraulic fracturing and drinking water...

2013-09-10

75

78 FR 20637 - Notification of Public Meeting and a Public Teleconference of the Hydraulic Fracturing Research...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Meeting and a Public Teleconference of the Hydraulic Fracturing Research Advisory Panel AGENCY...meeting and public teleconference of the Hydraulic Fracturing Research Advisory Panel to...EPA's Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water...

2013-04-05

76

75 FR 35023 - Informational Public Meetings for Hydraulic Fracturing Research Study  

Federal Register 2010, 2011, 2012, 2013, 2014

...FRL-9164-8] Informational Public Meetings for Hydraulic Fracturing Research Study AGENCY: Environmental...plan to study the relationship between hydraulic fracturing and drinking water. The meetings...plans during the meetings. DATES: The Hydraulic Fracturing Study informational...

2010-06-21

77

40 CFR 147.52 - State-administered program-Hydraulic Fracturing of Coal Beds.  

Code of Federal Regulations, 2010 CFR

...false State-administered program-Hydraulic Fracturing of Coal Beds. 147.52...52 State-administered program—Hydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in...

2010-07-01

78

[Hydraulic fracturing - a hazard for drinking water?].  

PubMed

Hydraulic fracturing (fracking) is a technique used to release and promote the extraction of natural gas (including shale gas, tight gas, and coal bed methane) from deep natural gas deposits. Among the German public there is great concern with regard to the potential environmental impacts of fracking including the contamination of ground water, the most important source of drinking water in Germany. In the present article the risks of ground water contamination through fracking are discussed. Due to the present safety requirements and the obligatory geological and hydrogeological scrutiny of the underground, which has to be performed prior to fracking, the risk of ground water contamination by fracking can be regarded as very low. The toxicity of chemical additives of fracking fluids is discussed. It is recommended that in the future environmental impact assessment and approval of fracs should be performed by the mining authorities in close cooperation with the water authorities. Furthermore, it is recommended that hydraulic fracturing in the future should be accompanied by obligatory ground water monitoring. PMID:24285158

Ewers, U; Gordalla, B; Frimmel, F

2013-11-01

79

Toughness-Dominated Regime of Hydraulic Fracturing in Cohesionless Materials  

NASA Astrophysics Data System (ADS)

This work examines the mechanisms of hydraulic fracturing in cohesionless particulate materials with geotechnical, geological, and petroleum applications. For this purpose, experimental techniques have been developed, and used to quantify the initiation and propagation of hydraulic fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, which are practically cohesionless. The liquid flow is localized in thin self-propagating crack-like conduits. By analogy we call them 'cracks' or 'hydraulic fractures.' When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. Because the particulate material is already 'fractured,' no new surface is created and no fracturing process per se is involved. Therefore, the conventional fracture mechanics principles cannot be directly applied. Based on the laboratory observations, performed on three particulate materials (Georgia Red Clay, silica flour, and fine sand, and their mixtures), this work offers physical concepts to explain the observed phenomena. The goal is to determine the controlling parameters of fracture behavior and to quantify their effects. An important conclusion of our work is that all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. The compressive stress state is an important characteristic of hydraulic fracturing in particulate materials with low, or no, cohesion (such as were used in our experiments). At present, two kinematic mechanisms of fracture propagation, consistent with the compressive stress regime, can be offered. The first mechanism is based on shear bands propagating ahead of the tip of an open fracture. The second is based on the tensile strain ahead of the fracture tip and reduction of the effective stresses to zero within the leak-off zone. Scaling indicates that in our experiments, there is a high pressure gradient in the leak-off zone in the direction normal to the fracture. Fluid pressure does not decrease considerably along the fracture, however, due to the relatively wide fracture aperture. This suggests that hydraulically induced fractures in unconsolidated materials may be considered to be within the toughness-dominated regime of hydraulic fracturing. Our results indicate that the primary influence on peak or initiation pressure comes from the remote stresses. However, fracture morphology changes significantly with other chosen parameters (stress, flow rate, rheology and permeability). Additionally, an important characteristic feature of fractures in our experiments is the frequent bluntness of the fracture tip, which suggests that plastic deformation at the fracture tip is important. Modeling shows that large openings at the fracture tip correspond to relatively large 'effective' fracture (surface) energy, which can be orders of magnitude greater than for typical (solid) rocks.

Germanovich, L. N.; Hurt, R. S.; Ayoub, J.; Norman, W. D.

2011-12-01

80

Hydraulic fracture height limits and fault interactions in tight oil and gas formations  

NASA Astrophysics Data System (ADS)

widespread use of hydraulic fracturing (HF) has raised concerns about potential upward migration of HF fluid and brine via induced fractures and faults. We developed a relationship that predicts maximum fracture height as a function of HF fluid volume. These predictions generally bound the vertical extent of microseismicity from over 12,000 HF stimulations across North America. All microseismic events were less than 600 m above well perforations, although most were much closer. Areas of shear displacement (including faults) estimated from microseismic data were comparatively small (radii on the order of 10 m or less). These findings suggest that fracture heights are limited by HF fluid volume regardless of whether the fluid interacts with faults. Direct hydraulic communication between tight formations and shallow groundwater via induced fractures and faults is not a realistic expectation based on the limitations on fracture height growth and potential fault slip.

Flewelling, Samuel A.; Tymchak, Matthew P.; Warpinski, Norm

2013-07-01

81

Observations of long period earthquakes accompanying hydraulic fracturing  

Microsoft Academic Search

Waveforms of most seismic events accompanying hydraulic fracturing have been reported to contain clear P and S waves and have fault plane solutions consistent with shear displacement across a fault. This observation is surprising since classical hydraulic fracturing theory predicts the creation of a tensile opening of a cavity in response to fluid pressure. Very small long period events, similar

Dorthe Bame; Michael Fehler

1986-01-01

82

A magnetic method for determining the geometry of hydraulic fractures  

USGS Publications Warehouse

We propose a method that may be used to determine the spatial orientation of the fracture plane developed during hydraulic fracture. In the method, magnetic particles are injected into the crack with the fracturing fluid so as to generate a sheet of magnetized material. Since the magnetization of a body with extreme dimension ratios, such as a crack, exceeds that of an equidimensional body and since this magnetization is sensitive both to orientation and geometry, this could be used to obtain information about the crack. By measuring the vertical and horizontal components of the magnetic field and field gradients at the earth's surface surrounding the injection well with superconducting magnetometers having 10-4 gamma sensitivity and also by measuring field direction within the well itself, it should be possible to calculate the orientation and perhaps infer the approximate geometry of the fracture surface. Experiments on electric field potential operated in conjunction with this experiment could further constrain estimates of shape and orientation. ?? 1976 Birkha??user Verlag.

Byerlee, J.D.; Johnston, M.J.S.

1976-01-01

83

Public health and high volume hydraulic fracturing.  

PubMed

High-volume horizontal hydraulic fracturing (HVHF) in unconventional gas reserves has vastly increased the potential for domestic natural gas production. HVHF has been promoted as a way to decrease dependence on foreign energy sources, replace dirtier energy sources like coal, and generate economic development. At the same time, activities related to expanded HVHF pose potential risks including ground- and surface water contamination, climate change, air pollution, and effects on worker health. HVHF has been largely approached as an issue of energy economics and environmental regulation, but it also has significant implications for public health. We argue that public health provides an important perspective on policymaking in this arena. The American Public Health Association (APHA) recently adopted a policy position for involvement of public health professionals in this issue. Building on that foundation, this commentary lays out a set of five perspectives that guide how public health can contribute to this conversation. PMID:23552646

Korfmacher, Katrina Smith; Jones, Walter A; Malone, Samantha L; Vinci, Leon F

2013-01-01

84

Hydraulic-fracturing controlled dynamics of microseismic clouds  

Microsoft Academic Search

Several dynamic processes related to propagation of hydraulic fracture modify the stress state in rocks and, therefore, they are relevant for triggering of microseismicity. For instance, these are the creation of a new fracture volume, fracturing fluid loss and its infiltration into reservoir rocks as well as diffusion of the injection pressure into the pore space of surrounding rocks and

S. A. Shapiro; C. Dinske; E. Rothert

2006-01-01

85

Hydraulic fracturing: paving the way for a sustainable future?  

PubMed

With the introduction of hydraulic fracturing technology, the United States has become the largest natural gas producer in the world with a substantial portion of the production coming from shale plays. In this review, we examined current hydraulic fracturing literature including associated wastewater management on quantity and quality of groundwater. We conclude that proper documentation/reporting systems for wastewater discharge and spills need to be enforced at the federal, state, and industrial level. Furthermore, Underground Injection Control (UIC) requirements under SDWA should be extended to hydraulic fracturing operations regardless if diesel fuel is used as a fracturing fluid or not. One of the biggest barriers that hinder the advancement of our knowledge on the hydraulic fracturing process is the lack of transparency of chemicals used in the practice. Federal laws mandating hydraulic companies to disclose fracturing fluid composition and concentration not only to federal and state regulatory agencies but also to health care professionals would encourage this practice. The full disclosure of fracturing chemicals will allow future research to fill knowledge gaps for a better understanding of the impacts of hydraulic fracturing on human health and the environment. PMID:24790614

Chen, Jiangang; Al-Wadei, Mohammed H; Kennedy, Rebekah C M; Terry, Paul D

2014-01-01

86

Microseismicity Induced by Hydraulic Fracturing in Oil and Gas Wells  

NASA Astrophysics Data System (ADS)

The detection and analysis of microseismicity induced by injection of fluids at high pressure has proved to be an effective technology for monitoring the placement of the fluid in applications such as hydraulic fracture stimulation of oil and gas wells, "shear-dilation" enhancement of hot-dry-rock reservoirs, waterflooding and tertiary recovery processes in oil reservoirs, CO2 injection for sequestration, drill cuttings injection, and many others. Microseismic mapping of hydraulic fractures, in particular, has grown into an extensive industry that provides critical information on many facets of fracture behavior and the overall geometry, with the results showing both expected and unexpected behavior in various tests. These industrial fractures are typically mapped with arrays of downhole tri-axial receivers placed in one or more wells at the reservoir level. With the number of microseismically mapped fractures now exceeding 1,000, numerous observations and inferences about fracture mechanisms can be made. In a large group of reservoirs, the created hydraulic fractures are mostly planar and follow a consistent azimuth. In other reservoirs, such as naturally fractured shales similar to the Barnett shale in the Fort Worth basin, the created fracture is highly dependent on the treatment. In these shale reservoirs, the use of viscous gels results in a mostly planar geometry, but stimulations with high-rate, large-volume "waterfracs" result in network fractures that may exceed 400 m by 1200 m in areal extent. In horizontal wells where several stages of these waterfracs are commonly pumped, the stages are found to often interfere and redirect subsequent stages. In many reservoirs, the heights of the hydraulic fractures have been found to be less than the expected heights based on known or inferred in situ stress contrasts between the reservoir layer and the bounding rocks, suggesting that some properties of the layering are important for limiting height growth. In lenticular sandstones, fractures are commonly observed to follow the sandstone lithologies and migrate upward or downward to remain within the accreted sandstone beds. A number of mapping tests have been performed in environments where the hydraulic fracture has interacted with faults. In such cases, the log-scale relative magnitudes of the events may suddenly increase by two or more. The faults often extend hundreds of meters upward or downward out of zone, or in directions different from the initial hydraulic fracture. Overall, the orientations and dimensions of the mapped fractures are providing the necessary information to optimize field development and improve hydraulic fracture effectiveness. In addition, these tests are providing important clues to help understand the geomechanical conditions of the reservoir and the changes induced by hydraulic fracturing.

Warpinski, N. R.; Maxwell, S.; Waltman, C.

2006-12-01

87

ECONOMIC RECOVERY OF OIL TRAPPED AT FAN MARGINS USING HIGH ANGLE WELLS AND MULTIPLE HYDRAULIC FRACTURES  

SciTech Connect

This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well was drilled during the first quarter of 1996. Well conditions resulted in the 7 in. production liner sticking approximately 900 ft off bottom. Therefore, a 5 in. production liner was necessary to case this portion of the target formation. Swept-out sand intervals and a poor cement bond behind the 5 in. liner precluded two of the three originally planned hydraulic fracture treatments. As a result, all pay intervals behind the 5 in. liner were perforated and stimulated with a non-acid reactive fluid. Following a short production period, the remaining pay intervals in the well (behind the 7 in. liner) were perforated. The well was returned to production to observe production trends and pressure behavior and assess the need to stimulate the new perforations.

Mike L. Laue

2001-09-28

88

Non-double-couple mechanisms of microearthquakes induced by hydraulic fracturing  

USGS Publications Warehouse

We have inverted polarity and amplitude information of representative microearthquakes to investigate source mechanisms of seismicity induced by hydraulic fracturing in the Carthage Cotton Valley, east Texas, gas field. With vertical arrays of four and eight three-component geophones in two monitoring wells, respectively, we were able to reliably determine source mechanisms of the strongest events with the best signal-to-noise ratio. Our analysis indicates predominantly non-double-couple source mechanisms with positive volumetric component consistent with opening cracks oriented close to expected hydraulic fracture orientation. Our observations suggest the induced events are directly the result of opening cracks by fluid injection, in contrast to many previous studies where the seismicity is interpreted to be primarily shearing caused by pore pressure diffusion into the surrounding rock or associated with shear stresses created at the hydraulic fracture tip. Copyright 2009 by the American Geophysical Union.

Sileny, J.; Hill, D.P.; Eisner, L.; Cornet, F.H.

2009-01-01

89

EPA Study of Hydraulic Fracturing and Drinking Water Resources  

EPA Science Inventory

In its FY2010 Appropriations Committee Conference Report, Congress directed EPA to study the relationship between hydraulic fracturing and drinking water, using: ? Best available science ? Independent sources of information ? Transparent, peer-reviewed process ? Consultatio...

90

Identification of Successful Practices in Hydraulic Fracturing Using  

E-print Network

1 Identification of Successful Practices in Hydraulic Fracturing Using Intelligent Data Mining the depletion and pressure decline in the field as new wells are drilled and put into production at different

Mohaghegh, Shahab

91

Influence of pressure change during hydraulic tests on fracture aperture.  

PubMed

In a series of field experiments, we evaluate the influence of a small water pressure change on fracture aperture during a hydraulic test. An experimental borehole is instrumented at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The target fracture for testing was found from the analyses of borehole logging and hydraulic tests. A double packer system was developed and installed in the test borehole to directly observe the aperture change due to water pressure change. Using this packer system, both aperture and flow rate are directly observed under various water pressures. Results indicate a slight change in fracture hydraulic head leads to an observable change in aperture. This suggests that aperture change should be considered when analyzing hydraulic test data from a sparsely fractured rock aquifer. PMID:22823750

Ji, Sung-Hoon; Koh, Yong-Kwon; Kuhlman, Kristopher L; Lee, Moo Yul; Choi, Jong Won

2013-03-01

92

An integrated geophysical and hydraulic investigation to characterize a fractured-rock aquifer, Norwalk, Connecticut  

USGS Publications Warehouse

The U.S. Geological Survey conducted an integrated geophysical and hydraulic investigation at the Norden Systems, Inc. site in Norwalk, Connecticut, where chlorinated solvents have contaminated a fractured-rock aquifer. Borehole, borehole-to-borehole, surface-geophysical, and hydraulic methods were used to characterize the site bedrock lithology and structure, fractures, and transmissive zone hydraulic properties. The geophysical and hydraulic methods included conventional logs, borehole imagery, borehole radar, flowmeter under ambient and stressed hydraulic conditions, and azimuthal square-array direct-current resistivity soundings. Integrated interpretation of geophysical logs at borehole and borehole-to-borehole scales indicates that the bedrock foliation strikes northwest and dips northeast, and strikes north-northeast to northeast and dips both southeast and northwest. Although steeply dipping fractures that cross-cut foliation are observed, most fractures are parallel or sub-parallel to foliation. Steeply dipping reflectors observed in the radar reflection data from three boreholes near the main building delineate a north-northeast trending feature interpreted as a fracture zone. Results of radar tomography conducted close to a suspected contaminant source area indicate that a zone of low electromagnetic (EM) velocity and high EM attenuation is present above 50 ft in depth - the region containing the highest density of fractures. Flowmeter logging was used to estimate hydraulic properties in the boreholes. Thirty-three transmissive fracture zones were identified in 11 of the boreholes. The vertical separation between transmissive zones typically is 10 to 20 ft. Open-hole and discrete-zone transmissivity was estimated from heat-pulse flowmeter data acquired under ambient and stressed conditions. The open-hole transmissivity ranges from 2 to 86 ft2/d. The estimated transmissivity of individual transmissive zones ranges from 0.4 to 68 ft2/d. Drawdown monitoring in nearby boreholes under pumping conditions identified hydraulic connections along a northeast-southwest trend between boreholes as far as 560 ft apart. The vertical distribution of fractures can be described by power law functions, which suggest that the fracture network contains transmissive zones consisting of closely spaced fractures surrounded by a less fractured and much less permeable rock mass.

Lane, J.W., Jr.; Williams, J.H.; Johnson, C.D.; Savino, D.M.; Haeni, F.P.

2002-01-01

93

Shear and tension hydraulic fractures in low permeability rocks  

USGS Publications Warehouse

Laboratory hydrofracture experiments were performed on triaxially stressed specimens of oil shale and low-permeability granite. The results show that either shear or tension fractures could develop depending on the level of differentials stress, even in specimens containing preexisting fractures. With 1 kb of confining pressure and differential stress greater than 2kb, hydraulic fluid diffusion into the specimens reduced the effective confining pressure until failure occurred by shear fracture. Below 2kb of differential stress, tension fractures occurred. These results suggest that hydraulic fracturing in regions of significant tectonic stress may produce shear rather than tension fractures. In this case in situ stress determinations based on presumed tension fractures would lead to erroneous results. ?? 1977 Birkha??user Verlag.

Solberg, P.; Lockner, D.; Byerlee, J.

1977-01-01

94

EPA releases progress report on hydraulic fracturing study  

NASA Astrophysics Data System (ADS)

The U.S. Environmental Protection Agency (EPA) provided a 21 December progress report on its ongoing national study about the potential impacts of hydraulic fracturing on drinking water resources. The agency said that a draft of the congressionally requested study will be released in 2014 for public and peer review and that its progress report does not draw conclusions about the potential impacts of hydraulic fracturing, often referred to as fracking.

Showstack, Randy

2013-01-01

95

78 FR 25267 - Request for Information To Inform Hydraulic Fracturing Research Related to Drinking Water Resources  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fracturing Research Related to Drinking Water Resources AGENCY: Environmental...impacts of hydraulic fracturing on drinking water resources from April 30, 2013...between hydraulic fracturing and drinking water resources. The EPA...

2013-04-30

96

77 FR 67361 - Request for Information To Inform Hydraulic Fracturing Research Related to Drinking Water Resources  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fracturing Research Related to Drinking Water Resources AGENCY: Environmental...impacts of hydraulic fracturing on drinking water resources. DATES: EPA will accept...between hydraulic fracturing and drinking water resources. EPA is...

2012-11-09

97

Locating microearthquakes induced by hydraulic fracturing in crystalline rock  

Microsoft Academic Search

Microearthquakes induced by hydraulic fracturing in crystalline rock at a depth of 3.5 km were located with a precision of better than 30 m to obtain information about the geometry and dimensions of the fracture system produced. The induced microseismicity was monitored by a network of five vorehole seismic stations; a total of about 800 induced events were reliably located

Leigh House

1987-01-01

98

Finite element modeling of hydraulic fracturing in 3D  

E-print Network

Mar 22, 2013 ... finite element formulation for the fracture and the rock. both with ... Hydraulic fracturing is the coupled dynamics of frac- ture and ?uid flow. .... given by Young's modulus E and Poisson ratio v as. vE E ... static pressure. Inserting ...

2013-03-22

99

Evaluation of a downhole tiltmeter array for monitoring hydraulic fractures  

SciTech Connect

A series of hydraulic-fracture experiments using a downhole tiltmeter array, called an inclinometer array, was conducted at the Department of Energy (DOE)/Gas Research Institute (GRI) Multi-Site facility in Colorado. The inclinometer array was used to measure the deformation of the reservoir rock in response to hydraulic fracture opening and confirm microseismically measured results. In addition, the inclinometer array was found to be a useful tool for accurately measuring closure stress, measuring residual widths of both propped and unpropped fractures, estimating proppant distribution, and evaluating values of in situ moduli.

Warpinski, N.R.; Engler, B.P. [Sandia National Labs., Albuquerque, NM (United States); Branagan, P.T.; Wilmer, R. [Branagan and Associates, Las Vegas, NV (United States); Wolhart, S.L. [Gas Research Inst., Chicago, IL (United States)

1997-03-01

100

Transient and Pseudosteady-State Productivity of Hydraulically Fractured Well  

E-print Network

in rectangular drainage area. They presented the effect of the drainage shape on the productivity and formalized the optimization technique based on the concept of proppant number for various reservoir geometry and number of fractures. 1.3 Research Objective... for proppant numbers less than 1. 29 There is an optimum fracture penetration ratio (Ix) for each given proppant number. Figure 3.10 shows the the optimum Ix for fractured vertical well and horizontal well with transverse fracture. Based...

Lumban Gaol, Ardhi

2012-10-19

101

Prediction of effects of hydraulic fracturing using reservoir and well flow simulation  

SciTech Connect

This paper presents a method to predict and evaluate effects of hydraulic fracturing jobs by using reservoir and well flow numerical simulation. The concept of the method i5 that steam production rate at the operating well head pressure is predicted with different fracture conditions which would be attained by the hydraulic fracturing jobs. Then, the effects of the hydraulic fracturing is evaluated by comparing the predicted steam production rate and that before the hydraulic fracturing. This course of analysis will suggest how large fracture should be created by the fracturing job to attain large enough increase in steam production at the operating condition and the best scheme of the hydraulic fracturing job.

Mineyuki Hanano; Tayuki Kondo

1992-01-01

102

An implicit level set method for modeling hydraulically driven fractures Anthony Peirce a,*, Emmanuel Detournay b  

E-print Network

An implicit level set method for modeling hydraulically driven fractures Anthony Peirce a the relevant tip asymptotics in hydraulic fracture simulators is critical for the accuracy and stability for a propagating hydraulic fracture. A number of char- acteristics of the governing equations for hydraulic

Peirce, Anthony

103

2006 GeoX Conference, pages 1 to 6 Characterisation of hydraulic fractures in  

E-print Network

2006 GeoX Conference, pages 1 to 6 Characterisation of hydraulic fractures in limestones using X, France Jacques.Desrues@hmg.inpg.fr ABSTRACT: Hydraulic tension fractures were produced in porous, hydraulic fracture, permeability tensor MOTS-CLÃ?S: microtomographie, fracturation hydraulique, tenseur de

104

Enrichment strategies and convergence properties of the XFEM for hydraulic fracture problems  

E-print Network

Enrichment strategies and convergence properties of the XFEM for hydraulic fracture problems Finite Ele- ment Method (XFEM) for modeling hydraulic fractures (HF), two classes of boundary value energy, is not suitable for modeling hydraulic fractures in which the uid and the fracture fronts

Peirce, Anthony

105

Using seismic tomography to characterize fracture systems induced by hydraulic fracturing  

SciTech Connect

Microearthquakes induced by hydraulic fracturing have been studied by many investigators to characterize fracture systems created by the fracturing process and to better understand the locations of energy resources in the earth`s subsurface. The pattern of the locations often contains a great deal of information about the fracture system stimulated during the hydraulic fracturing. Seismic tomography has found applications in many areas for characterizing the subsurface of the earth. It is well known that fractures in rock influence both the P and S velocities of the rock. The influence of the fractures is a function of the geometry of the fractures, the apertures and number of fractures, and the presence of fluids in the fractures. In addition, the temporal evolution of the created fracture system can be inferred from the temporal changes in seismic velocity and the pattern of microearthquake locations. Seismic tomography has been used to infer the spatial location of a fracture system in a reservoir that was created by hydraulic fracturing.

Fehler, M.; Rutledge, J.

1995-01-01

106

Interference Fracturing: Non-Uniform Distributions of Perforation Clusters that Promote Simultaneous Growth of Multiple Hydraulic Fractures  

E-print Network

Simultaneous Growth of Multiple Hydraulic Fractures A.P. Peirce, University of British Columbia and A.P. Bunger in horizontal well stimulation is the generation of hydraulic fractures (HFs) from all perforation clusters shadowing" that refers to suppression of some hydraulic fractures by the compressive stresses exerted

Peirce, Anthony

107

Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs  

SciTech Connect

The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical issues in tight gas fracturing, in particular the roles of gel damage, polymer loading (water-frac versus gel frac), and proppant concentration on the created fracture conductivity. To achieve this objective, we have designed the experimental apparatus to conduct the dynamic fracture conductivity tests. The experimental apparatus has been built and some preliminary tests have been conducted to test the apparatus.

Stephen Holditch; A. Daniel Hill; D. Zhu

2007-06-19

108

Investigation of the effect of gel residue on hydraulic fracture conductivity using dynamic fracture conductivity test  

E-print Network

(Economides and Nolte 2000). The first fracture treatment was performed with gelled crude. Later on, gelled kerosene was used. Presently, many different types of fracturing fluids are used in hydraulic fracturing treatments. Water-based polymer solutions..., oil-based polymer solutions, water-in-oil polymer solutions, and different kind of polymers have been used in the industry. Aqueous fluids (such as acid, water and brines) are now commonly used as the base fluid for all fracturing treatments used...

Marpaung, Fivman

2008-10-10

109

Determining the distribution of hydraulic conductivity in a fractured limestone aquifer by simultaneous injection and geophysical logging  

USGS Publications Warehouse

A field technique for assessing the vertical distribution of hydraulic conductivity in an aquifer was applied to a fractured carbonate formation in southeastern Nevada. The technique combines the simultaneous use of fluid injection and geophysical logging to measure in situ vertical distributions of fluid velocity and hydraulic head down the borehole; these data subsequently are analyzed to arrive at quantitative estimates of hydraulic conductivity across discrete intervals in the aquifer. The results of this analysis identified the contact margin between the Anchor and Dawn Members of the Monte Cristo Limestone as being the dominant transmissive unit. -from Authors

Morin, R.H.; Hess, A.E.; Paillet, F.L.

1988-01-01

110

Occupational exposures to respirable crystalline silica during hydraulic fracturing.  

PubMed

This report describes a previously uncharacterized occupational health hazard: work crew exposures to respirable crystalline silica during hydraulic fracturing. Hydraulic fracturing involves high pressure injection of large volumes of water and sand, and smaller quantities of well treatment chemicals, into a gas or oil well to fracture shale or other rock formations, allowing more efficient recovery of hydrocarbons from a petroleum-bearing reservoir. Crystalline silica ("frac sand") is commonly used as a proppant to hold open cracks and fissures created by hydraulic pressure. Each stage of the process requires hundreds of thousands of pounds of quartz-containing sand; millions of pounds may be needed for all zones of a well. Mechanical handling of frac sand creates respirable crystalline silica dust, a potential exposure hazard for workers. Researchers at the National Institute for Occupational Safety and Health collected 111 personal breathing zone samples at 11 sites in five states to evaluate worker exposures to respirable crystalline silica during hydraulic fracturing. At each of the 11 sites, full-shift samples exceeded occupational health criteria (e.g., the Occupational Safety and Health Administration calculated permissible exposure limit, the NIOSH recommended exposure limit, or the ACGIH threshold limit value), in some cases, by 10 or more times the occupational health criteria. Based on these evaluations, an occupational health hazard was determined to exist for workplace exposures to crystalline silica. Seven points of dust generation were identified, including sand handling machinery and dust generated from the work site itself. Recommendations to control exposures include product substitution (when feasible), engineering controls or modifications to sand handling machinery, administrative controls, and use of personal protective equipment. To our knowledge, this represents the first systematic study of work crew exposures to crystalline silica during hydraulic fracturing. Companies that conduct hydraulic fracturing using silica sand should evaluate their operations to determine the potential for worker exposure to respirable crystalline silica and implement controls as necessary to protect workers. PMID:23679563

Esswein, Eric J; Breitenstein, Michael; Snawder, John; Kiefer, Max; Sieber, W Karl

2013-01-01

111

Hydraulic tomography offers improved imaging of heterogeneity in fractured rocks.  

PubMed

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. PMID:24749939

Illman, Walter A

2014-01-01

112

Effects of fracturing fluid recovery upon well performance and ultimate recovery of hydraulically fractured gas wells  

E-print Network

- Initial Cr = 10 . . Effects of Initial Flow Contitions on Gas Production With Water Injection Initial Reservoir Pressure = 7, 800 psi - Initial Cr = 10. , . . . 109 . . . . . 110 CIIAPTER I INTRODUCIION In low permeability gas reservoirs, hydraulic... immediately surrounding the kactute had a minor effect on the productivity of a hydraulically fractured well. Van Poollen showed that a decrease in fracture conductivity will reduce the productivity of a well more than similar damage to the permeability...

Berthelot, Jan Marie

2012-06-07

113

Interwell Tracer Analyses of a Hydraulically Fractured Granitic Geothermal Reservoir  

Microsoft Academic Search

Radioisotopic tracer techniques using I¹³¹ and Br⁸² with downhole gamma logging have been used successfully at temperatures up to 200°C (392°F) and depths to 3 km (10,000 ft) to characterize quantitatively flow at injection and production points in hydraulically fractured regions in granite, including mapping of fracture intersections with wellbores. RTD techniques using sodium fluorescein and Br⁸² tracers were developed

Jefferson Tester; Robert Bivins; Robert Potter

1982-01-01

114

Characterizing Hydraulic Properties and Ground-Water Chemistry in Fractured-Rock Aquifers: A User's Manual  

E-print Network

Characterizing Hydraulic Properties and Ground-Water Chemistry in Fractured-Rock Aquifers: A User., 2007, Characterizing hydraulic properties and ground-water chemistry in fractured-rock aquifers: A user

115

75 FR 36387 - Informational Public Meetings for Hydraulic Fracturing Research Study; Correction  

Federal Register 2010, 2011, 2012, 2013, 2014

...AGENCY [FRL-9168-2] Informational Public Meetings for Hydraulic Fracturing Research Study; Correction AGENCY: Environmental...Register of June 21, 2010, announcing public meetings for the Hydraulic Fracturing Research Study. The document contained an...

2010-06-25

116

The use of broadband microseisms for hydraulic fracture mapping  

SciTech Connect

When a hydrocarbon reservoir is subjected to a hydraulic fracture treatment, the cracking and slipping of the formation results in the emission of seismic energy. The objective of this study was to determine the advantages of using broadband (100 Hz to 1500 M) microseismic emissions to map a hydraulic fracture treatment. A hydraulic fracture experiment was performed in the Piceance Basin of Western Colorado to induce and record broadband microseismic events. The formation was subjected to four processes; break-down/ballout, step-rate test, KCL mini-fracture, and linear-gel mini-fracture. Broadband microseisms were successfully recorded by a novel three-component wall-locked seismic accelerometer package, placed in an observation well 211 ft (64 m) offset from the treatment well. During the two hours of formation treatment, more than 1200 significant microseismic events were observed. The occurrences of the events strongly correlated with the injection bore-bole pressures during the treatments. Using both hodogram analysis and time of arrival information, estimates of the origination point of the seismic events were computed. A map of the event locations yielded a fracture orientation estimate consistent with the known orientation of the field in the formation. This paper describes the technique for acquiring and analyzing broadband microseismic events and illustrate how the new broadband approach can enhance signal detectability and event location resolution.

Sleefe, G.E.; Warpinski, N.R.; Engler, B.P.

1993-08-01

117

Upscaling in vertically fractured oil reservoirs using homogenization  

Microsoft Academic Search

Flow modeling in fractured reservoirs is largely confined to the so-called sugar cube model. Here, however, we consider vertically fractured reservoirs, i.e., the situation that the reservoir geometry can be approximated by fractures enclosed columns running from the base rock to the cap rock (aggregated columns). This article deals with the application of the homogenization method to derive an upscaled

H. Salimi; H. Bruining

2009-01-01

118

Investigation of Created Fracture Geometry through Hydraulic Fracture Treatment Analysis  

E-print Network

fracture geometry illustrates that it is not possible to reach the full fracture geometry implied by microseismic given the finite amount of fluid and proppant that was pumped. The model does show however that the created geometry appears to be much larger...

Ahmed, Ibraheem 1987-

2012-11-30

119

Laboratory hydraulic fracturing experiments in intact and pre-fractured rock  

Microsoft Academic Search

Laboratory hydraulic fracturing experiments were conducted to investigate two factors which could influence the use of the hydrofrac technique for in-situ stress determinations; the possible dependence of the breakdown pressure upon the rate of borehole pressurization, and the influence of pre-existing cracks on the orientation of generated fractures. The experiments have shown that while the rate of borehole pressurization has

M. D. Zoback; R. Rummel; R. Jung; C. B. Raleigh

1977-01-01

120

40 CFR 147.52 - State-administered program-Hydraulic Fracturing of Coal Beds.  

Code of Federal Regulations, 2012 CFR

...State-administered program-Hydraulic Fracturing of Coal Beds. 147.52 Section 147.52 Protection...State-administered program—Hydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State of Alabama,...

2012-07-01

121

40 CFR 147.52 - State-administered program-Hydraulic Fracturing of Coal Beds.  

Code of Federal Regulations, 2013 CFR

...State-administered program-Hydraulic Fracturing of Coal Beds. 147.52 Section 147.52 Protection...State-administered program—Hydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State of Alabama,...

2013-07-01

122

Self-similar solutions for a fractional thin film equation governing hydraulic fractures  

E-print Network

Self-similar solutions for a fractional thin film equation governing hydraulic fractures C. Imbert equation governing hydraulic fractures are constructed. One of the boundary con- ditions, which accounts, 35R11, 35C06 Keywords: Hydraulic fractures, higher order equation, thin films, fractional Laplacian

Boyer, Edmond

123

Microseismic mapping of a Cotton Valley hydraulic fracture using decimated downhole arrays J.T. Rutledge  

E-print Network

Microseismic mapping of a Cotton Valley hydraulic fracture using decimated downhole arrays J three hydraulic fracture operations in the Cotton Valley gas field of East Texas. Two 48-level, 3 a consortia of operators and service companies conducted an extensive hydraulic fracture imaging demonstration

124

Hydraulic Fracturing and Horizontal Gas Well Drilling Reference List Updated December 7, 2011  

E-print Network

Hydraulic Fracturing and Horizontal Gas Well Drilling Reference List Updated December 7, 2011 of Hydraulic Fracturing in the Shale Plays (2010). Tudor Pickering Holt & Co with Reservoir Research Partners, with a thoughtful discussion Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources

Manning, Sturt

125

Hydraulic Fracturing and Horizontal Gas Well Drilling Reference List Updated June 23, 2011  

E-print Network

Hydraulic Fracturing and Horizontal Gas Well Drilling Reference List Updated June 23, 2011 of Hydraulic Fracturing in the Shale Plays (2010). Tudor Pickering Holt & Co with Reservoir Research Partners, with a thoughtful discussion Draft Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water

126

New Tracers Identify Hydraulic Fracturing Fluids and Accidental Releases from Oil and Gas Operations  

E-print Network

New Tracers Identify Hydraulic Fracturing Fluids and Accidental Releases from Oil and Gas fingerprints of fluids that return to the surface after high volume hydraulic fracturing of unconventional oil the hydraulic fracturing process, resulting in the relative enrichment of boron and lithium in HFFF

Jackson, Robert B.

127

A Hybrid, Neuro-Genetic Approach to Hydraulic Fracture Treatment Design and Optimization  

E-print Network

SPE 36602 A Hybrid, Neuro-Genetic Approach to Hydraulic Fracture Treatment Design and Optimization and novel methodology for optimal design of hydraulic fracture treatments in a gas storage field. What makes very little (almost none) reservoir data availability. Lack of engineering data for hydraulic fracture

Mohaghegh, Shahab

128

Coupling schemes for modeling hydraulic fracture propagation using the XFEM Elizaveta Gordeliy, Anthony Peirce  

E-print Network

Coupling schemes for modeling hydraulic fracture propagation using the XFEM Elizaveta Gordeliy August 2012 Accepted 18 August 2012 Available online 15 September 2012 Keywords: XFEM Hydraulic fractures and the Dirichlet to Neumann (DN) map with Oðh� accuracy. For hydraulic fracture problems with a lag separating

Peirce, Anthony

129

Review article Induced seismicity and hydraulic fracturing for the recovery of  

E-print Network

Review article Induced seismicity and hydraulic fracturing for the recovery of hydrocarbons Richard mining (M 1.0e5.2); (h) geothermal operations (M 1.0e4.6) and (i) hydraulic fracturing for recovery seismicity occurs due to a reduction in effective stress on fault planes. Hydraulic fracturing operations can

Foulger, G. R.

130

International Journal of Rock Mechanics & Mining Sciences 44 (2007) 739757 Computer simulation of hydraulic fractures  

E-print Network

of hydraulic fractures J. Adachia , E. Siebritsb , A. Peircec,Ã?, J. Desrochesd a Schlumberger Data of hydraulic fracturing models for use in the petroleum and other industries. We discuss scaling laws and the propagation regimes that control the growth of hydraulic fractures from the laboratory to the field scale. We

Peirce, Anthony

131

On the moving boundary conditions for a hydraulic fracture Emmanuel Detournay a,b,  

E-print Network

On the moving boundary conditions for a hydraulic fracture Emmanuel Detournay a,b, , Anthony Peirce 2014 Keywords: Hydraulic fractures Speed equation Ill-posedness a b s t r a c t This paper re-examines the boundary conditions at the moving front of a hydraulic fracture when the fluid front has coalesced

Peirce, Anthony

132

Numerical modeling of hydraulic fracture problem in permeable medium using cohesive zone model  

E-print Network

Numerical modeling of hydraulic fracture problem in permeable medium using cohesive zone model-off dominated. We demonstrate the ability of our cohesive zone model in simulating the hydraulic fracture in all these propagation regimes. Keywords: Hydraulic fracture, Cohesive zone model, Finite element analysis, Hydro

Paris-Sud XI, Université de

133

40 CFR 147.52 - State-administered program-Hydraulic Fracturing of Coal Beds.  

Code of Federal Regulations, 2011 CFR

...State-administered program-Hydraulic Fracturing of Coal Beds. 147.52 Section 147.52 Protection...State-administered program—Hydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State of Alabama,...

2011-07-01

134

77 FR 38024 - Oil and Gas; Well Stimulation, Including Hydraulic Fracturing, on Federal and Indian Lands  

Federal Register 2010, 2011, 2012, 2013, 2014

...and Gas; Well Stimulation, Including Hydraulic Fracturing, on Federal and Indian Lands...Register a proposed rule to regulate hydraulic fracturing on public land and Indian...disclosure to the public of chemicals used in hydraulic fracturing on public land and...

2012-06-26

135

Analytic crack solutions for tilt fields around hydraulic fractures  

SciTech Connect

The recent development of downhole tiltmeter arrays for monitoring hydraulic fractures has provided new information on fracture growth and geometry. These downhole arrays offer the significant advantages of being close to the fracture (large signal) and being unaffected by the free surface. As with surface tiltmeter data, analysis of these measurements requires the inversion of a crack or dislocation model. To supplement the dislocation models of Davis [1983], Okada [1992] and others, this work has extended several elastic crack solutions to provide tilt calculations. The solutions include constant-pressure 2D, penny-shaped, and 3D-elliptic cracks and a 2D-variable-pressure crack. Equations are developed for an arbitrary inclined fracture in an infinite elastic space. Effects of fracture height, fracture length, fracture dip, fracture azimuth, fracture width and monitoring distance on the tilt distribution are given, as well as comparisons with the dislocation model. The results show that the tilt measurements are very sensitive to the fracture dimensions, but also that it is difficult to separate the competing effects of the various parameters.

Warpinski, N.R.

2000-01-05

136

Water Use for Hydraulic Fracturing: A Texas Sized Problem?  

E-print Network

The state of Texas could face a 2.7 trillion gallon shortfall of water by 2060. Hydraulic fracturing (HF) requires large amounts of water for each well. Tax incentives should be offered to companies that substitute brackish groundwater for fresh...

LeClere, David

137

Potential Relationships Between Hydraulic Fracturing and Drinking Water Resources  

EPA Science Inventory

The conferees urge the Agency to carry out a study on the relationship between hydraulic fracturing and drinking water, using a credible approach that relies on the best available science, as well as independent sources of information. The conferees expect the study to be conduct...

138

Monitoring the width of hydraulic fractures with acoustic waves  

Microsoft Academic Search

For a direct determination of the width, the resolution of the signal is required to distinguish the reflections that are related with two distinct fluid\\/solid interfaces delimiting the hydraulic fracture from its solid embedding. To make this distinction, the solid\\/fluid interfaces must be separated at least one eighth of a wavelength and represent sufficient impedance contrast. The applicability of the

Jeroen Groenenboom; Jacob T. Fokkema

1998-01-01

139

Measuring in situ vertical hydraulic conductivity in tidal environments  

NASA Astrophysics Data System (ADS)

The hydraulic conductivity of intertidal sediments plays an important role in quantifying seawater-groundwater interactions. However, its accurate and economical in situ evaluation is difficult since available in situ methods do not apply in intertidal zones due to periodic tidal fluctuations. Here a new apparatus is presented for measuring the sediments' vertical hydraulic conductivity in tidal environments and a simple, finite-difference data analysis method is proposed to estimate this key parameter. The new apparatus is easy to operate, and is able to measure in situ vertical hydraulic conductivity ranging from 10-7 m/s to 10-2 m/s in tidal environments within one hour. A posteriori error of the finite-difference approximation method is estimated to have the same magnitude order as the square of the nondimensionalized observation time interval K?t/(LV) (here ?t is the observation time interval, Rd is the diameter ratio of the falling-head water-container standpipe to the undisturbed in situ sediment sample, K is the vertical hydraulic conductivity, and LV is the sample length), which is usually a very small number. The new apparatus and finite-difference method were verified by numerical simulations and many in situ experiments in several coastal case study sites of Bohai Sea, PR China. The finite-difference method has adequate accuracy in estimating the hydraulic conductivity compared with the traditional least-squares fitting method. The relative error between the estimates by the two methods is less than 9.41% and averages 1.22% for all experiments. The new apparatus and simple finite-difference method are recommended for in situ experiment that have many advantages such as economy, efficiency, reliability, and simplicity.

Wang, Xuejing; Li, Hailong; Yang, Jinzhi; Wan, Li; Wang, Xusheng; Jiang, Xiaowei; Guo, Huaming

2014-08-01

140

A Rapid Method of Predicting Width and Extent of Hydraulically Induced Fractures  

Microsoft Academic Search

During the hydraulic-fracturing treatment of an oil or gas well, the liquid pressure in the borehole is increased until tensile stress in the surrounding rock exceeds tensile strength. Once a tensile fracture is initiated, it is penetrated by liquid from the borehole and fracture propagation under continuous hydraulic action takes place. The fracturing liquid carries a propping agent to insure

J. Geertsma; F. de Klerk

1969-01-01

141

Injection-Sensitive Mechanics of Hydraulic Fracture Interaction with Discontinuities  

NASA Astrophysics Data System (ADS)

We develop a new analytical model, called OpenT, that solves the elasticity problem of a hydraulic fracture (HF) contact with a pre-existing discontinuity natural fracture (NF) and the condition for HF re-initiation at the NF. The model also accounts for fluid penetration into the permeable NFs. For any angle of fracture intersection, the elastic problem of a blunted dislocation discontinuity is solved for the opening and sliding generated at the discontinuity. The sites and orientations of a new tensile crack nucleation are determined based on a mixed stress- and energy-criterion. In the case of tilted fracture intersection, the finite offset of the new crack initiation point along the discontinuity is computed. We show that aside from known controlling parameters such stress contrast, cohesional and frictional properties of the NFs and angle of intersection, the fluid injection parameters such as the injection rate and the fluid viscosity are of first-order in the crossing behavior. The model is compared to three independent laboratory experiments, analytical criteria of Blanton, extended Renshaw-Pollard, as well as fully coupled numerical simulations. The relative computational efficiency of OpenT model (compared to the numerical models) makes the model attractive for implementation in modern engineering tools simulating hydraulic fracture propagation in naturally fractured environments.

Chuprakov, D.; Melchaeva, O.; Prioul, R.

2014-09-01

142

Imaging Hydraulic Fractures: Source Location Uncertainty Analysis At The UPRC Carthage Test Site  

E-print Network

Hydraulic fracturing is a useful tool for enhancing gas and oil production. High-resolution seismic imaging of the fracture geometry and fracture growth process is the key in determining optimal spacing and location of ...

Li, Yingping

1996-01-01

143

An investigation of productivity increases from hydraulic fracturing treatments  

E-print Network

AN INVESTIGATION OF PRODUCTIVITY INCREASES FROM HYDRAULIC FRACTURING TREATMENTS A Thesis b7 Robert Joe Boriskie Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment of the requirements... Head of Department) August, 1963 1. ABSTRACT 2. INTRODUCTION. TABLE OF CONTENTS PRgB 3. THEORY AND PROCEDURE. 4. DISCUSSION OF RESULTS. . 5. CONCLUSIONS. 6. ACKNOWLEDGEMENT. 7. APPENDIX. 8. REFERENCES. 18 19 20 32 LIST OF FIGURES...

Boriskie, Robert Joe

2012-06-07

144

Hydraulic fracturing theory for conditions of thermal stress  

Microsoft Academic Search

Thermal stresses associated with a temperature change of only 10°C are on the order of 10 to 100 bars. This illustrates the important influence thermal stresses can impose on the results of rock stress measurements by the hydraulic fracturing method. In order to examine the problem, expressions are derived to describe the stress field produced by non-steady state heat conduction

G. Stephens; B. Voight

1982-01-01

145

Mathematical modeling of hydraulic fracturing in coal seams  

SciTech Connect

Hydraulic fracturing of coal seam is considered as a process of development of discontinuities in rock mass elements due to change in hydrogeomechanical situation on filtration of fluid under pressure. Failure is associated with excess of the effective stresses over the rock tension strength. The problem on filtration and failure of massif is solved by the finite-element method using the procedure of fictitious nodal forces.

Olovyanny, A.G. [All Russian Science Research Institute for Mine Surveying, St. Petersburg (Russian Federation)

2005-02-01

146

Upscaling in Vertically Fractured Oil Reservoirs Using Homogenization  

Microsoft Academic Search

Flow modeling in fractured reservoirs is largely confined to the so-called sugar cube model. Here, however, we consider vertically\\u000a fractured reservoirs, i.e., the situation that the reservoir geometry can be approximated by fractures enclosed columns running\\u000a from the base rock to the cap rock (aggregated columns). This article deals with the application of the homogenization method\\u000a to derive an upscaled

Hamidreza Salimi; Hans Bruining

2010-01-01

147

Effects of skin and hydraulic fractures on SVE wells.  

PubMed

Soil vapor extraction (SVE) systems are intended to cause substantial volumes of air to flow through the subsurface with the purpose of removing volatile contaminants. The effectiveness of SVE can be influenced by any effect that changes the specific gas capacity (discharge as a function of vacuum) of a well. Skins of low permeability material enveloping a well bore are widely recognized to affect the performance of wells used to recover water, natural gas, or petroleum, and skin can also significantly diminish the performance of an SVE well. Skins a few mm thick consisting of material whose gas phase permeability is 0.01 of the formation can reduce the specific gas capacity of an SVE well by factors of 2 to 10 or more. Hydraulic fractures created in the vicinities of shallow wells commonly resemble sand-filled layers shaped like flat-lying disks or gently dipping saucers. The contrast between the gas-phase permeability of the sand in the fracture and that of the formation is particularly important, with significant effects requiring the ratio to be greater than approximately 50. Shallow hydraulic fractures filled with several tenths of m3 of sand in formations that are several orders of magnitude less permeable than that of the enveloping formation should increase specific gas capacity by factors of 10 or more. Field tests of the effects of hydraulic fractures on the performance of SVE were conducted by creating four wells intersecting fractures and a suite of control wells created using conventional methods in silty saprolite. Specific gas capacities ranged over more than an order of magnitude for 10 wells completed within a small area (2 m2) and at the same depth. Specific capacities correlate to the drilling method that was used to create the bore for the well: lowest values occurred in wells drilled with a machine auger, slightly better results were obtained using a Shelby tube, and the best results were obtained from conventional wells bored with a hand auger. Skin factors determined for wells created with a machine auger could be explained by a layer 1 cm thick that has 0.007 times the permeability of the enveloping material, which could readily have been created during the drilling procedure. Specific capacities of wells intersecting hydraulic fractures were 5 to 100 times more than those of conventional wells. The large difference in performance appears to be due in part to the beneficial effects of the fracture, and in part to the detrimental effects of well skin. PMID:15854720

Bradner, Graham C; Murdoch, Lawrence C

2005-05-01

148

Implicit level set schemes for modeling hydraulic fractures using the Elizaveta Gordeliy, Anthony Peirce  

E-print Network

Implicit level set schemes for modeling hydraulic fractures using the XFEM Elizaveta Gordeliy Copyright Ã? 2013 Published by Elsevier B.V. All rights reserved. 1. Introduction Hydraulic fractures (HF form 13 July 2013 Accepted 27 July 2013 Available online 20 August 2013 Keywords: XFEM Hydraulic

Peirce, Anthony

149

Interaction between Injection Points during Hydraulic Fracturing Kjetil M. D. Hals1,  

E-print Network

Interaction between Injection Points during Hydraulic Fracturing Kjetil M. D. Hals1, and Inga Berre between two injection points during hydraulic fracturing (hydrofracking) and how this interaction of Mathematics, University of Bergen, P.O. Box 7800, NO-5020 Bergen, Norway. We present a model of the hydraulic

Santos, Juan

150

Uncertainty in the maximum principal stress estimated from hydraulic fracturing measurements due to the presence of the induced fracture  

Microsoft Academic Search

The classical theory for hydraulic fracturing stress measurements assumes an ideal case with a linear elastic, homogenous, and isotropic medium; and a fracture that reopens distinctly when the minimum tangential borehole stress is exceeded. The induced fracture disturbs this ideal picture in several aspects, which are important for the evaluation of the maximum horizontal principal stress using the fracture reopening

Jonny Rutqvist; Chin-Fu Tsang; Ove Stephansson

2000-01-01

151

Page 1 of 5 Narrative Description of Hydraulic Fracturing Draft Regulations  

E-print Network

Page 1 of 5 Narrative Description of Hydraulic Fracturing Draft Regulations The Department of Conservation has released a discussion draft of hydraulic fracturing (HF) regulations. This narrative attempts formation (i.e., higher than the strata's "fracture pressure"). In HF, a fluid with #12;Page 2 of 5

152

Investigation of the effect of gel residue on hydraulic fracture conductivity using dynamic fracture conductivity test  

E-print Network

The key to producing gas from tight gas reservoirs is to create a long, highly conductive flow path, via the placement of a hydraulic fracture, to stimulate flow from the reservoir to the wellbore. Viscous fluid is used to transport proppant...

Marpaung, Fivman

2009-05-15

153

Self potential improves characterization of hydraulically-active fractures from azimuthal geoelectrical measurements  

NASA Astrophysics Data System (ADS)

We examined the sensitivity of azimuthal self potential (ASP) and azimuthal resistivity surveys (ARS) to hydraulic anisotropy in a laboratory fracture block model. Both ASP and ARS measurements are influenced by anisotropy (due to the strike of major fracture sets) and heterogeneity (due to variable fracture density) of the block model. The polarity of the self potential defines the flow direction and the self potential magnitude within a single fracture set is observed to increase with flow rate. Whereas the ARS anisotropy is primarily controlled by fracture density/connectivity (and hence presumably hydraulic conductivity) ASP anisotropy appears diagnostic of (1) hydraulic gradient driving flow within fracture sets, and (2) fracture density (presumably controlling the strength of the streaming potential coefficient). Preliminary field data from the New Jersey Highlands illustrate that ASP surveys can define hydraulic anisotropy in fractured rock environments. Our results suggest that combined interpretation of ASP and ARS can lead to improved geoelectrical characterization of fracture rock anisotropy.

Wishart, DeBonne N.; Slater, Lee D.; Gates, Alexander E.

2006-09-01

154

The Role of the Rock on Hydraulic Fracturing of Tight Shales  

NASA Astrophysics Data System (ADS)

Successful economic production of oil and gas from nano-darcy-range permeability, tight shale reservoirs, is achieved via massive hydraulic fracturing. This is so despite their limited hydrocarbon in place, on per unit rock volume basis. As a reference, consider a typical average porosity of 6% and an average hydrocarbon saturation of 50% to 75%. The importance of tight shales results from their large areal extent and vertical thickness. For example, the areal extent of the Anwar field in Saudi Arabia of 3230 square miles (and 300 ft thick), while the Marcellus shale alone is over 100,000 square miles (and 70 to 150 ft thick). The low permeability of the rock matrix, the predominantly mineralized rock fabric, and the high capillary forces to both brines and hydrocarbons, restrict the mobility of pore fluids in these reservoirs. Thus, one anticipates that fluids do not move very far within tight shales. Successful production, therefore results from maximizing the surface area of contact with the reservoir by massive hydraulic fracturing from horizontal bore holes. This was the conceptual breakthrough of the previous decade and the one that triggered the emergence of gas shales, and recently oily shales, as important economic sources of energy. It is now understood that the process can be made substantially more efficient, more sustainable, and more cost effective by understanding the rock. This will be the breakthrough of this decade. Microseismic monitoring, mass balance calculations, and laboratory experiments of hydraulic fracturing on tight shales indicate the development of fracture complexity and fracture propagation that can not be explained in detail in this layered heterogeneous media. It is now clear that in tight shales the large-scale formation fabric is responsible for fracture complexity. For example, the presence and pervasiveness of mineralized fractures, bed interfaces, lithologic contacts, and other types of discontinuities, and their orientation in relation to the in-situ stresses, have a dominant role in promoting fracture branching and abrupt changes in direction. In general, the problem can be conceptualized as a competition between the effect of stresses (traditional mechanics of homogeneous media) and the effect of rock fabric (the mechanics of heterogeneous media). When the stress difference is low and the rock fabric pronounced, the rock fabric defines the direction of propagation. When the stress difference is high and the fabric is weak, the stress contrast dominates the process. In real systems, both effects compete and result in the complexity that we infer from indirect observations. In this paper we discuss the role of rock fabric on fracture complexity during hydraulic fracture propagation. We show that understanding the far field stresses is not enough to understand fracture propagation and complexity. Understanding the rock-specifically the larger-scale textural features that define the reservoir fabric-is fundamental to understand fracture complexity and fracture containment. We use laboratory experiments with acoustic emission localization to monitor fracturing and making inferences about the large-scale rock behavior. We also show that the fracture geometry, even for the same connected surface area, has significant well production and reservoir recovery implications.

Suarez-Rivera, R.; Green, S.; Stanchits, S.; Yang, Y.

2011-12-01

155

Importance of Stratabound Fracture Networks for Seismic Hazard Assessment of Hydraulic Fracturing  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing, a powerful completion technique used to enhance oil or gas production from impermeable strata, may trigger unintended earthquake activity. The primary basis for assessment of triggered and natural seismic hazard is the classic Gutenberg-Richter (G-R) relation, which expresses scale-independent behavior of earthquake magnitudes. Using a stochastic approach to simulate microseismicity from three monitoring programs in North America, we show that magnitude-distance trends for microearthquakes induced by hydraulic fracturing may deviate significantly from the G-R relation. This apparent breakdown in the power-law scaling paradigm, coupled with unusually high values for the b-parameter (slope) of the G-R relation, can be explained by a new model based on activation of stratabound fracture networks in which fracture height growth is limited by mechanical bed thickness. For the three areas considered, mechanical bed thickness is well represented by a lognormal distribution, which leads asymptotically to a Gaussian decay for induced magnitudes that fits the observations remarkably well. This new relationship has profound implications for understanding the scaling behavior of induced microearthquakes, as well as for forecasting the probability of larger earthquakes triggered by hydraulic fracturing in oil and gas development.

Eaton, D. W.; Davidsen, J.; Pedersen, P. K.; Boroumand, N.

2013-12-01

156

Constraints on upward migration of hydraulic fracturing fluid and brine.  

PubMed

Recent increases in the use of hydraulic fracturing (HF) to aid extraction of oil and gas from black shales have raised concerns regarding potential environmental effects associated with predictions of upward migration of HF fluid and brine. Some recent studies have suggested that such upward migration can be large and that timescales for migration can be as short as a few years. In this article, we discuss the physical constraints on upward fluid migration from black shales (e.g., the Marcellus, Bakken, and Eagle Ford) to shallow aquifers, taking into account the potential changes to the subsurface brought about by HF. Our review of the literature indicates that HF affects a very limited portion of the entire thickness of the overlying bedrock and therefore, is unable to create direct hydraulic communication between black shales and shallow aquifers via induced fractures. As a result, upward migration of HF fluid and brine is controlled by preexisting hydraulic gradients and bedrock permeability. We show that in cases where there is an upward gradient, permeability is low, upward flow rates are low, and mean travel times are long (often >10? ?years). Consequently, the recently proposed rapid upward migration of brine and HF fluid, predicted to occur as a result of increased HF activity, does not appear to be physically plausible. Unrealistically high estimates of upward flow are the result of invalid assumptions about HF and the hydrogeology of sedimentary basins. PMID:23895673

Flewelling, Samuel A; Sharma, Manu

2014-01-01

157

Estimation of response of fracture system to hydraulic stimulation by induced microseismic multiplet analysis  

NASA Astrophysics Data System (ADS)

Development of a commercial geothermal power plant using an artificially stimulated reservoir is underway at Cooper Basin, Australia. In 2003, they have made the first stimulation where openhole section from 3667-4421m inside granitic basement was stimulated. Researchers in Tohoku University have collected more than 32,000 microseismic events while the stimulation using a monitoring network consists of 4 near surface stations (horizontal offset around 5-7 km from the injection well) and one downhole station near the injection well. Sub-horizontal hypocentral cloud with a thickness around 100-200m have been obtained by JHD in the previous studies (Asanuma et al., SEG Exp. Abst., 2005). In this study, the authors clustered and re-located microseismic multiplets using coherence evaluation in the frequency domain and DD relocation technique. Evaluation of coherency of the seismic traces at the onset of P-wave revealed that 99.9% of the events, which are not saturated and overlapped two events, were clustered into one multiplet cluster. This is because of strong low-pass characteristics of the earth transfer function and simple rupture process. The events were then sub-clustered into 26 groups by their polarity of the first break of P wave at each station. Integrated interpretation of the multiplets using fault plane solutions (FPS) by the composite focal mechanism, spatio-temporal distribution of the hypocenter, and critical stress state for shear slip was made in this study. Results from the analyses revealed that most of the multiplets occurred on sub-horizontal fractures, and some of the multiplet events (a few percent) are very likely to origin from sub-vertical fractures which connect the sub-horizontal fractures. It has been also showed that the events from sub-vertical fracture started to occur after seismic activity in one sub-horizontal fracture became high, and other sub-horizontal fracture was seismically activated after appearance of sub-vertical seismic structure. Kumano et al. (SEG Exp. Abst., 2006) have made coherence analysis of multiplets including coda, and reported that two or three sub-parallel and sub-horizontal fractures were mainly stimulated at this site. It has been reported that several sub-horizontal permeable fractures have been found inside the basement rock while drilling of the injection well, and most of the pre-existing fractures were plugged by cement except for one. Integrated interpretation of the observed facts and results from the microseismic analysis is that (a) an existing fracture connected to the injection well was firstly stimulated, then (b) increased pore-pressure in the fracture induced shear slip on sub-vertical fractures and permeability improved, and (c) horizontal fractures, which were hydraulically connected by the sub-vertical fractures, were stimulated and seismically activated. A combination of multiplet analysis, FPS, and critical pore pressure was effectively used to interpret behavior of simulated fracture system.

Asanuma, H.; Kenmoku, Y.; Kawamura, Y.; Niitsuma, H.; Wyborn, D.

2009-12-01

158

Three-dimensional thermal model for interpreting distributed temperature sensing data during hydraulic fracturing.  

E-print Network

??Distributed Temperature Sensing (DTS) can provide the wellbore temperature profile during the hydraulic fracturing treatment. This temperature profile is a complex function of many parameters… (more)

Amini, Kaveh

2014-01-01

159

The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs  

E-print Network

the surface area of the formation that is connected to the wellbore. These highly conductive fractures significantly increase the production rates of petroleum fluids. During the process of hydraulic fracturing proppant is pumped and distributed...

Kamenov, Anton

2013-04-11

160

Development, setup and testing of a dynamic hydraulic fracture conductivity apparatus  

E-print Network

One of the most critical parameters in the success of a hydraulic fracturing treatment is to have sufficiently high fracture conductivity. Unbroken polymers can cause permeability impairment in the proppant pack and/or in the matrix along...

Pongthunya, Potcharaporn

2009-06-02

161

A New Analytical Method to Quantify Residual Fluid Cleanup in Hydraulic Fractures  

E-print Network

A number of factors contribute to reduce the production benefits from hydraulic fracturing, including inefficient fluid design, poor proppant selection and or, the inability of fracture fluid to degrade and flow back after treatment. Undegraded...

Zarrin, Tahira

2014-04-17

162

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils  

E-print Network

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils Jianting Zhu August 2003. [1] In hydroclimate and land-atmospheric interaction models, effective hydraulic properties are needed at large grid scales. In this study, the effective soil hydraulic parameters of the areally

Mohanty, Binayak P.

163

Hydraulic fracturing and wellbore completion of coalbed methane wells in the Powder River Basin, Wyoming: Implications for water and gas production  

SciTech Connect

Excessive water production (more than 7000 bbl/month per well) from many coalbed methane (CBM) wells in the Powder River Basin of Wyoming is also associated with significant delays in the time it takes for gas production to begin. Analysis of about 550 water-enhancement activities carried out during well completion demonstrates that such activities result in hydraulic fracturing of the coal. Water-enhancement activities, consists of pumping 60 bbl of water/min into the coal seam during approximately 15 min. This is done to clean the well-bore and to enhance CBM production. Hydraulic fracturing is of concern because vertical hydraulic fracture growth could extend into adjacent formations and potentially result in excess CBM water production and inefficient depressurization of coals. Analysis of the pressure-time records of the water-enhancement tests enabled us to determine the magnitude of the least principal stress (S{sub 3}) in the coal seams of 372 wells. These data reveal that because S{sub 3} switches between the minimum horizontal stress and the overburden at different locations, both vertical and horizontal hydraulic fracture growth is inferred to occur in the basin, depending on the exact location and coal layer. Relatively low water production is observed for wells with inferred horizontal fractures, whereas all of the wells associated with excessive water production are characterized by inferred vertical hydraulic fractures. The reason wells with exceptionally high water production show delays in gas production appears to be inefficient depressurization of the coal caused by water production from the formations outside the coal. To minimize CBM water production, we recommend that in areas of known vertical fracture propagation, the injection rate during the water-enhancement tests should be reduced to prevent the propagation of induced fractures into adjacent water-bearing formations.

Colmenares, L.B.; Zoback, M.D. [Stanford University, Stanford, CA (United States). Dept. of Geophysics

2007-01-15

164

Numerical Modeling of Hydraulic Fracture Propagation Using Thermo-hydro-mechanical Analysis with Brittle Damage Model by Finite Element Method.  

E-print Network

??Better understanding and control of crack growth direction during hydraulic fracturing are essential for enhancing productivity of geothermal and petroleum reservoirs. Structural analysis of fracture… (more)

Min, Kyoung

2013-01-01

165

Field Experiments in a Fractured Clay Till: 1. Hydraulic Conductivity and Fracture Aperture  

Microsoft Academic Search

Field values of horizontal hydraulic conductivity measured in the upper 1.5–5.5 m of a weathered and fractured clay-rich till were strongly influenced by smearing around piezometer intakes, which occurs during augering, and by the physical scale of the measuring device. Values measured in conventional augered piezometers were typically 1–2 orders of magnitude lower than those measured in piezometers designed to

Larry D. McKay; John A. Cherry; Robert W. Gillham

1993-01-01

166

Hydraulics of horizontal wells in fractured shallow aquifer systems Eungyu Parka,*, Hongbin Zhanb  

E-print Network

Hydraulics of horizontal wells in fractured shallow aquifer systems Eungyu Parka,*, Hongbin Zhanb Accepted 1 May 2003 Abstract An analysis of groundwater hydraulic head in the vicinity of a horizontal well in fractured or porous aquifers considering confined, leaky confined, and water-table aquifer boundary

Zhan, Hongbin

167

Hydromechanical interactions in a fractured carbonate reservoir inferred from hydraulic and mechanical measurements  

E-print Network

Hydromechanical interactions in a fractured carbonate reservoir inferred from hydraulic, France Abstract Hydromechanical coupled processes in a shallow fractured carbonate reservoir rock were of hydraulic loading/unloading of a water reservoir in which fluid flow occurs mainly inside a heterogeneous

Paris-Sud XI, Université de

168

Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources (Monterey, CA)  

EPA Science Inventory

A summary of EPA's research relating to potential impacts of hydraulic fracturing on drinking water resources will be presented. Background about the study plan development will be presented along with an analysis of the water cycle as it relates to hydraulic fracturing processe...

169

Deviation of hydraulic fractures through poroelastic stress changes induced by fluid injection and pumping  

Microsoft Academic Search

This paper presents an analysis of the deviation of hydraulic fractures associated with the poroelastic change of the in situ stress field caused by fluid injection and pumping in the reservoir. This mechanism is studied within the confines of a simple model involving one injection and one pumping well, and a hydraulic fracture propagating along the path initially equidistant from

I. Berchenko; E. Detournay

1997-01-01

170

Imaging hydraulic fractures in a geothermal reservoir Bruce R. Julian,1,2  

E-print Network

Click Here for Full Article Imaging hydraulic fractures in a geothermal reservoir Bruce R. Julian,1, B. R., G. R. Foulger, F. C. Monastero, and S. Bjornstad (2010), Imaging hydraulic fractures, and a total loss of drilling mud occurred at a depth of about 2672 m while injecting water at rates up to 20 l

Foulger, G. R.

171

Final Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources  

EPA Science Inventory

The overall purpose of this study is to elucidate the relationship, if any, between hydraulic fracturing and drinking water resources. More specifically, the study has been designed to assess the potential impacts of hydraulic fracturing on drinking water resources and to identif...

172

Application of harmonic analysis of water levels to determine vertical hydraulic conductivities in clay-rich aquitards.  

PubMed

A harmonic analysis method was used to determine vertical hydraulic conductivities (Kv) in geologic media between vertically separated piezometers using water level measurements. In this method, each water level time series was filtered and then decomposed using harmonic analysis into a sum of trigonometric components. The phase and amplitude of each harmonic function were calculated. These data were used to estimate Kv values between vertically separated data sets assuming one-dimensional transient flow. The method was applied to water level data collected from nested piezometers at two thick clay-rich till aquitards in Saskatchewan, Canada. At one site, routine water levels were measured in 12 piezometers (installed between 1 and 29 m below ground surface) since installation (1995). At the other site, water levels were measured in seven piezometers (installed between 4 and 53 m below ground surface) since installation (1998-1999). The Kv calculated using harmonic analysis decreased with depth below the water table at both sites, approaching matrix estimates of hydraulic conductivity between 10 and 11 m and between 21 and 43 m below ground surface. These depths reflected the depth of extensive vertical fracturing at the sites and showed that the depth of fracturing may be site specific. PMID:12873014

Boldt-Leppin, Brigitte E J; Hendry, M Jim

2003-01-01

173

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

USGS Publications Warehouse

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.

Day-Lewis, F. D.; Hsieh, P.A.; Gorelick, S.M.

2000-01-01

174

A methodology for using borehole temperature-depth profiles under ambient, single and cross-borehole pumping conditions to estimate fracture hydraulic properties  

NASA Astrophysics Data System (ADS)

In fractured aquifers flow generally takes place in a few fractured zones. The identification of these main flow paths is critical as it controls the transfer of fluids in the subsurface. For realistic modeling of the flow the knowledge about the spatial variability of hydraulic properties is required. Inverse problems based on hydraulic head data are generally strongly underconstrained. A possible way of reducing the uncertainty is to combine different type of data, such as flow measurements, temperature profiles or tracer test data. Here, we focus on the use of temperature, which can be seen as a natural tracer of ground water flow. Previous studies used temperature anomalies to quantify vertical or horizontal regional groundwater flow velocities. Most of these studies assume that water in the borehole is stagnant, and, thus, the temperature profile in the well is representative of the temperature in the aquifer. In fractured media, differences in hydraulic head between flow paths connected to a borehole generally create ambient vertical flow within the borehole. These differences in hydraulic head are in general due to regional flow conditions. Estimation of borehole vertical flow is of interest as it can be used to derive large scale hydraulic connections. Under a single-borehole configuration, the estimation of vertical flow can be used to estimate the local transimissivities and the hydraulic head differences driving the flow through the borehole. Under a cross-borehole set up, it can be used to characterize hydraulic connections and estimate their hydraulic properties. Using a flow and heat transfer numerical model, we find that the slope of the temperature profile is related directly to vertical borehole flow velocity. Thus, we propose a method to invert temperature measurements to derive borehole flow velocities and subsequently the fracture zone hydraulic and connectivity properties. The advantage of temperature measurements compared to flowmeter measurements is that temperature can be measured easily and very accurately, continuously in space and time. To test the methodology, we have performed a field experiment at a crystalline rocks field site, located in Ploemeur, Brittany (France). The site is composed of three 100 meters deep boreholes, located at 6-10 m distances from each other. The experiment consisted in measuring the borehole temperature profiles under all possible pumping configurations. Hence, the pumping and monitoring wells were successively changed. The thermal response in observation well induced by changes in pumping conditions is related to changes in vertical flow velocities and thus to the inter-borehole fracture connectivity. Based on this dataset, we propose a methodology to include temperature profiles in inverse problem for characterizing the spatial distribution of fracture zone hydraulic properties.

Klepikova, M.; Le Borgne, T.; Bour, O.; Lavenant, N.

2011-12-01

175

TECHNOLOGY EVALUATION AND APPLICATIONS ANALYSIS REPORT: UNIVERSITY OF CINCINNATI/RISK REDUCTION ENGINEERING LABORATORY - HYDRAULIC FRACTURING TECHNOLOGY  

EPA Science Inventory

Two pilot-scale demonstrations of the hydraulic fracturing technology for enhancing the permeability of contaminated silty clays have been evaluated under the Superfund Innovative Technology Evaluation (SITE) Program.The hydraulic fracturing technology was demonstrated in 1991 an...

176

Hydraulic characterization for steam enhanced remediation conducted in fractured rock.  

PubMed

To explore the viability of Steam Enhanced Remediation (SER) in fractured rock a small-scale steam injection and water/vapour extraction pilot study was conducted at the former Loring Air Force Base in northern Maine, USA. A detailed well testing program was undertaken to assist in the design of the injection and extraction well array, and to assess the possibility of off-site heat and contaminant migration. A structurally complex limestone having low matrix porosity and a sparse distribution of fractures underlies the study site. To characterize the groundwater and steam flow pathways, single-well slug tests and more than 100 pulse interference tests were conducted. The results of the well testing indicate that the study site is dominated by steeply dipping bedding plane fractures that are interconnected only between some wells in the injection/extraction array. The SER system was designed to take advantage of interconnected fractures located at depth in the eastern end of the site. An array of 29 wells located in an area of 60 by 40 m was used for steam injection and water/vapour extraction. The migration of heat was monitored in several wells using thermistor arrays having a 1.5 m vertical spacing. Temperature measurements obtained during and after the 3 month steam injection period showed that heat migration generally occurred along those fracture features identified by the pulse interference testing. Based on these results, it is concluded that the pulse interference tests were valuable in assisting with the design of the injection/extraction well geometry and in predicting the migration pathways of the hot water associated with the steam injection. The pulse interference test method should also prove useful in support of any other remedial method dependant on the fracture network for delivery of remedial fluid or extraction of contaminants. PMID:16310888

Stephenson, Kyle M; Novakowski, Kent; Davis, Eva; Heron, Gorm

2006-01-10

177

In-situ stress from hydraulic fracture measurements in G Tunnel, Nevada Test Site  

SciTech Connect

Hydraulic fracture work in G Tunnel, Nevada Test Site, performed to obtain the in-situ stress state is discussed. Field equipment and procedures are described; analysis is developed to relate the hydraulic fracture pressures to the in-situ stress state. Pressure data are analyzed to provide estimates of the stress state at a number of locations in the tunnel complex. A unique feature of the work is the mineback - a mining process in which the rock is cut away to reveal the actual plane of the fracture. Advantages, limitations, and problem areas associated with extracting in-situ stress fields from hydraulic fracture pressure records are discussed in detail.

Smith, C.; Vollendorf, W. C.; Warren, W. E.

1981-04-01

178

Hydraulic fracture extending into network in shale: reviewing influence factors and their mechanism.  

PubMed

Hydraulic fracture in shale reservoir presents complex network propagation, which has essential difference with traditional plane biwing fracture at forming mechanism. Based on the research results of experiments, field fracturing practice, theory analysis, and numerical simulation, the influence factors and their mechanism of hydraulic fracture extending into network in shale have been systematically analyzed and discussed. Research results show that the fracture propagation in shale reservoir is influenced by the geological and the engineering factors, which includes rock mineral composition, rock mechanical properties, horizontal stress field, natural fractures, treating net pressure, fracturing fluid viscosity, and fracturing scale. This study has important theoretical value and practical significance to understand fracture network propagation mechanism in shale reservoir and contributes to improving the science and efficiency of shale reservoir fracturing design. PMID:25032240

Ren, Lan; Zhao, Jinzhou; Hu, Yongquan

2014-01-01

179

Hydraulic Fracture Extending into Network in Shale: Reviewing Influence Factors and Their Mechanism  

PubMed Central

Hydraulic fracture in shale reservoir presents complex network propagation, which has essential difference with traditional plane biwing fracture at forming mechanism. Based on the research results of experiments, field fracturing practice, theory analysis, and numerical simulation, the influence factors and their mechanism of hydraulic fracture extending into network in shale have been systematically analyzed and discussed. Research results show that the fracture propagation in shale reservoir is influenced by the geological and the engineering factors, which includes rock mineral composition, rock mechanical properties, horizontal stress field, natural fractures, treating net pressure, fracturing fluid viscosity, and fracturing scale. This study has important theoretical value and practical significance to understand fracture network propagation mechanism in shale reservoir and contributes to improving the science and efficiency of shale reservoir fracturing design. PMID:25032240

Ren, Lan; Zhao, Jinzhou; Hu, Yongquan

2014-01-01

180

Application of characteristic time concepts for hydraulic fracture configuration design, control, and optimization  

SciTech Connect

The analysis of pertinent energy components or affiliated characteristic times for hydraulic stimulation processes serves as an effective tool for fracture configuration designs optimization, and control. This evaluation, in conjunction with parametric sensitivity studies, provides a rational base for quantifying dominant process mechanisms and the roles of specified reservoir properties relative to controllable hydraulic fracture variables for a wide spectrum of treatment scenarios. Results are detailed for the following multi-task effort: (a) Application of characteristic time concept and parametric sensitivity studies for specialized fracture geometries (rectangular, penny-shaped, elliptical) and three-layered elliptic crack models (in situ stress, elastic moduli, and fracture toughness contrasts). (b) Incorporation of leak-off effects for models investigated in (a). (c) Simulation of generalized hydraulic fracture models and investigation of the role of controllable vaxiables and uncontrollable system properties. (d) Development of guidelines for hydraulic fracture design and optimization.

Advani, S.H.; Lee, T.S. (Lehigh Univ., Bethlehem, PA (United States)); Moon, H. (Ohio State Univ., Columbus, OH (United States))

1992-10-01

181

Application of characteristic time concepts for hydraulic fracture configuration design, control, and optimization. Final report  

SciTech Connect

The analysis of pertinent energy components or affiliated characteristic times for hydraulic stimulation processes serves as an effective tool for fracture configuration designs optimization, and control. This evaluation, in conjunction with parametric sensitivity studies, provides a rational base for quantifying dominant process mechanisms and the roles of specified reservoir properties relative to controllable hydraulic fracture variables for a wide spectrum of treatment scenarios. Results are detailed for the following multi-task effort: (a) Application of characteristic time concept and parametric sensitivity studies for specialized fracture geometries (rectangular, penny-shaped, elliptical) and three-layered elliptic crack models (in situ stress, elastic moduli, and fracture toughness contrasts). (b) Incorporation of leak-off effects for models investigated in (a). (c) Simulation of generalized hydraulic fracture models and investigation of the role of controllable vaxiables and uncontrollable system properties. (d) Development of guidelines for hydraulic fracture design and optimization.

Advani, S.H.; Lee, T.S. [Lehigh Univ., Bethlehem, PA (United States); Moon, H. [Ohio State Univ., Columbus, OH (United States)

1992-10-01

182

Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers  

NASA Astrophysics Data System (ADS)

gas extracted from hydraulically fractured shale formations potentially has a big impact on the global energy landscape. However, there are concerns of potential environmental impacts of hydraulic fracturing of the shale formations, particularly those related to water quality. To evaluate the potential impact of hydraulically fractured shale on overlying aquifers, we conduct realizations of numerical modeling simulations to assess fluid flow and chloride transport from a synthetic Bowland Shale over a period of 11,000 years. The synthetic fractured shale was represented by a three-dimensional discrete fracture model that was developed by using the data from a Bowland Shale gas exploration in Lancashire, UK. Chloride mass exchange between fractures and the rock matrix was fully accounted for in the model. The assessment was carried out to investigate fluid and chloride mass fluxes before, during, and after hydraulic fracturing of the Bowland Shale. Impacts of the upward fracture height and aperture, as well as hydraulic conductivity of the multilayered bedrock system, are also included this assessment. This modeling revealed that the hydraulically fractured Bowland Shale is unlikely to pose a risk to its overlying groundwater quality when the induced fracture aperture is ?200 µm. With the fracture aperture ?1000 µm, the upward chloride flux becomes very sensitive to the upward fracture height growth and hydraulic conductivity of the multilayered bedrock system. In the extremely unlikely event of the upward fracture growth directly connecting the shale formation to the overlying Sherwood Sandstone aquifer with the fracture aperture ?1000 µm, the upward chloride mass flux could potentially pose risks to the overlying aquifer in 100 years. The model study also revealed that the upward mass flux is significantly intercepted by the horizontal mass flux within a high permeable layer between the Bowland Shale and its overlying aquifers, reducing further upward flux toward the overlying aquifers.

Cai, Zuansi; Ofterdinger, Ulrich

2014-07-01

183

A methodology for using borehole temperature-depth profiles under ambient, single and cross-borehole pumping conditions to estimate fracture hydraulic properties  

NASA Astrophysics Data System (ADS)

SummaryTemperature profiles in the subsurface are known to be sensitive to groundwater flow. Here we show that they are also strongly related to vertical flow in the boreholes themselves. Based on a numerical model of flow and heat transfer at the borehole scale, we propose a method to invert temperature measurements to derive borehole flow velocities. This method is applied to an experimental site in fractured crystalline rocks. Vertical flow velocities deduced from the inversion of temperature measurements are compared with direct heat-pulse flowmeter measurements showing a good agreement over two orders of magnitudes. Applying this methodology under ambient, single and cross-borehole pumping conditions allows us to estimate fracture hydraulic head and local transmissivity, as well as inter-borehole fracture connectivity. Thus, these results provide new insights on how to include temperature profiles in inverse problems for estimating hydraulic fracture properties.

Klepikova, Maria V.; Le Borgne, Tanguy; Bour, Olivier; Davy, Philippe

2011-09-01

184

Predictable Factors for Dural Tears in Lumbar Burst Fractures with Vertical Laminar Fractures  

PubMed Central

Objective The purpose of the present study was to determine the incidence of dural tears and predictable factors suggesting dural tears in patients who had lumbar burst fractures with vertical laminar fractures. Methods A retrospective review was done on thirty-one patients who underwent operative treatment for lumbar burst fractures with vertical laminar fractures between January 2003 and December 2008. All patients were divided into two groups according to existence of dural tears, which were surgically confirmed; 21 patients with dural tears and 10 patients without dural tears. Clinical and radiographic findings were analyzed for their association with dural tears. Results Among a total of 31 patients, dural tears were detected in 21 (67%) patients. A preoperative neurological deficits and mean separation distances of the edges in laminar fractures were found to be the reliable factors of dural tears (p=0.001 and 0.002, respectively). Decreased ratio of the central canal diameter and interpedicular distance were also the reliable factors suggesting dural tears (p=0.006 and 0.015, respectively). However, dural tears showed no significant association with age, sex, level of injury, absence of a posterior fat pad signal, the angle of retropulsed segment, or site of laminar fracture. Conclusion Our study of lumbar burst fracture combined laminar fracture revealed that dural tears should be ruled out in cases of a preoperative neurological deficits, wide separation of the laminar fracture, severe canal encroachment, and wider interpedicular distance. PMID:21892398

Park, Jin-Kyu; Park, Jin-Woo; Sung, Joo-Kyung

2011-01-01

185

Analysis of the classical pseudo-3D model for hydraulic fracture with equilibrium height growth across stress barriers  

E-print Network

Analysis of the classical pseudo-3D model for hydraulic fracture with equilibrium height growth in revised form 13 February 2010 Accepted 10 March 2010 Keywords: Hydraulic fracture P3D Symmetric stress-called ``pseudo three-dimensional'' (P3D) model for a hydraulic fracture with equilibrium height growth across two

Peirce, Anthony

186

Reply: Davies et al. (2012), Hydraulic fractures: How far can they go? Richard J. Davies a,*, Gillian R. Foulger a  

E-print Network

Discussion Reply: Davies et al. (2012), Hydraulic fractures: How far can they go? Richard J. Davies and natural hydraulic fractures caused by high fluid pressure from eight sedimentary successions from around the world. They found the tallest natural hydraulic fractures to be w1133 m in height and the tallest upward

Foulger, G. R.

187

Temporal and spatial scaling of hydraulic response to recharge in fractured aquifers: Insights from a frequency domain analysis  

E-print Network

Temporal and spatial scaling of hydraulic response to recharge in fractured aquifers: Insights from investigate the hydraulic response to recharge of a fractured aquifer, using a frequency domain approach scaling of hydraulic response to recharge in fractured aquifers: Insights from a frequency domain analysis

Paris-Sud XI, Université de

188

Determination of stress state in deep subsea formation by combination of hydraulic fracturing in situ test and core  

E-print Network

Determination of stress state in deep subsea formation by combination of hydraulic fracturing January 2013. [1] In situ test of hydraulic fracturing (HF) provides the only way to observe in situ of stress state in deep subsea formation by combination of hydraulic fracturing in situ test and core

189

In Situ Characterization of a Single Fracture Hydromechanical Behavior from Hydraulic Pulse Tests coupled to Simultaneous Pressure Normal  

E-print Network

In Situ Characterization of a Single Fracture Hydromechanical Behavior from Hydraulic Pulse Tests of the other surrounding fractures of the network. 1 INTRODUCTION Hydraulic pulse injection testing in single borehole has previously been applied to determine hydraulic properties of rock fractures, including

Vallée, Martin

190

Analysis of the classical pseudo-3D model for hydraulic fracture with equilibrium height growth across stress barriers  

E-print Network

Analysis of the classical pseudo-3D model for hydraulic fracture with equilibrium height growth t This paper deals with the so-called ``pseudo three-dimensional'' (P3D) model for a hydraulic fracture of the length, height, and aperture of the hydraulic fracture, in contrast to the numerical formulations adopted

Peirce, Anthony

191

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/, Vibrational modes of hydraulic fractures: Inference1  

E-print Network

:53am D R A F T #12;X - 2 LIPOVSKY AND DUNHAM: RESONANCE OF HYDRAULIC FRACTURES Abstract. Oscillatory seismic signals arising from resonant vibrations of4 hydraulic fractures are observed in many geologic of hydraulic fracture events. We present a25 D R A F T May 14, 2014, 1:53am D R A F T #12;LIPOVSKY AND DUNHAM

Dunham, Eric M.

192

77 FR 36273 - Public Meeting on Draft Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Draft Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel Fuels...the use of diesel fuels in oil and gas hydraulic fracturing and to solicit input during...Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel...

2012-06-18

193

Hydraulic Fracture Propagation through Preexisting Discontinuity Monitored by Acoustic Emission and Ultrasonic Transmission  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing is critical to enhance hydrocarbon production from ultra-low permeability unconventional reservoirs, and is the common completion methodology for tight formations around the world. Unfortunately, these reservoirs are often highly heterogeneous and their heterogeneity imparts a degree of geometrical complexity in hydraulic fractures that is poorly understood. Fracture complexity (e.g. branching) results in higher surface area and could be beneficial to production provided it remains conductive. Understanding the sources and consequences of fracture complexity is thus of high importance to completion and production operations. In this study we postulate that textural complexity in tight heterogeneous formations induces fracture complexity, and that the main sources of textural complexity are associated with veins, bed boundaries, lithologic contacts, and geologic interfaces. We thus study the effect of interfaces on hydraulic fracture propagation under laboratory conditions by Acoustic Emission (AE) and Ultrasonic Transmission (UT) monitoring techniques. The experiments were conducted on low permeability sandstone blocks of 279 x 279 x 381 mm length with saw cut discontinuities oriented orthogonally to the expected direction of fracture propagation. The rock is loaded in a poly-axial test frame to representative effective in-situ stress conditions of normal and deviatoric stress. Hydraulic fracturing was initiated by injection of silicon oil into a borehole drilled off center from the block. Acoustic emission (AE) events were continuously monitored during testing using nineteen P-wave sensors. Additional sensors were installed to periodically monitor ultrasonic transmission (UT) along various directions oblique and perpendicular to the fracture and the interface. The AE and UT data were recorded using a Vallen AMSY-6 system, with 16-bit amplitude resolution and 5 MHz sampling rate. Detailed analysis of AE localizations allowed us to identify various stages of hydraulic fracturing, including fracture initiation, fracture interaction with the preexisting interface, fracture propagation and fracture closing. Observed variations in UT amplitudes and velocities, during fracture propagation, were related to fracture propagation, as well as to the penetration of fracturing fluid to the conductive interface. Analysis of the combined AE and UT data provides additional insight into the fracturing process and significantly improved our understanding of the dynamics of hydraulic fracture propagation. Detailed post-test 3D mapping of the final fracture allowed us to make an independent comparison of actual fracture and the fracture monitored by the AE and UT measurements. This comparison is essential for validating the interpretation of microseismic monitoring during hydraulic fracturing in the lab and in the field.

Stanchits, S.; Lund, J.; Surdi, A.; Edelman, E.; Whitney, N.; Eldredge, R.; Suarez-Rivera, R.

2011-12-01

194

French vertical flow constructed wetlands: reed bed behaviour and limits due to hydraulic overloading on first stage filters  

E-print Network

French vertical flow constructed wetlands: reed bed behaviour and limits due to hydraulic with the European standards. Keywords: Vertical flow constructed wetlands; hydraulic overload; hydraulic behaviour. INTRODUCTION Vertical flow constructed wetlands (VFCWs) have been very successful in France over the last five

Paris-Sud XI, Université de

195

Application of microseismic technology to hydraulic fracture diagnostics: GRI/DOE Field Fracturing Multi-Sites Project  

SciTech Connect

The objective of the Field Fracturing Multi-Sites Project (M-Site) is to conduct field experiments and analyze data that will result in definitive determinations of hydraulic fracture dimensions using remote well and treatment well diagnostic techniques. In addition, experiments will be conducted to provide data that will resolve significant unknowns with regard to hydraulic fracture modeling, fracture fluid rheology and fracture treatment design. These experiments will be supported by a well-characterized subsurface environment as well as surface facilities and equipment conducive to acquiring high-quality data. It is anticipated that the project`s research advancements will provide a foundation for a fracture diagnostic service industry and hydraulic fracture optimization based on measured fracture response. The M-Site Project is jointly sponsored by the Gas Research Institute (GRI) and the US Department of Energy (DOE). The site developed for M-Site hydraulic fracture experimentation is the former DOE Multiwell Experiment (MWX) site located near Rifle, Colorado. The MWX project drilled three closely-spaced wells (MWX-1, MWX-2 and MWX-3) which were the basis for extensive reservoir analyses and tight gas sand characterizations in the blanket and lenticular sandstone bodies of the Mesaverde Group. The research results and background knowledge gained from the MWX project are directly applicable to research in the current M-Site Project.

Wilmer, R. [CER Corp., Las Vegas, NV (United States); Warpinski, N.R. [Sandia National Laboratories (United States); Wright, T.B. [Resources Engineering Systems (United States); Branagan, P.T. [Branagan & Associates (United States); Fix, J.E. [Fix & Associates (United States)

1995-06-01

196

Self potential improves characterization of hydraulically-active fractures from azimuthal geoelectrical measurements  

Microsoft Academic Search

We examined the sensitivity of azimuthal self potential (ASP) and azimuthal resistivity surveys (ARS) to hydraulic anisotropy in a laboratory fracture block model. Both ASP and ARS measurements are influenced by anisotropy (due to the strike of major fracture sets) and heterogeneity (due to variable fracture density) of the block model. The polarity of the self potential defines the flow

DeBonne N. Wishart; Lee D. Slater; Alexander E. Gates

2006-01-01

197

Theoretical size of hydraulically induced horizontal fractures and corresponding surface uplift in an idealized medium  

Microsoft Academic Search

For the disposal of radioactive wastes by hydraulic fracturing and grout injection, it is considered essential that the induced fractures be nearly horizontal. Bottom-hole injection pressure in excess of overburden pressure has been recognized as one indication that fracturing is horizontal. The amount of uplift of the ground surface caused by the injection can be used as another indicator. For

Ren Jen Sun

1969-01-01

198

Hydraulic fracture initiation and propagation: roles of wellbore trajectory, perforation and stress regimes  

Microsoft Academic Search

This paper develops a generic model for predicting hydraulic fracture initiation from arbitrarily oriented wellbores. For a given in-situ stress condition and wellbore orientation parameters, the model predicts the fracture initiation pressure and the orientation and location of fractures on the wellbore wall. The model has been applied in a series of in-situ stress conditions to study the effect of

M. M Hossain; M. K Rahman; S. S Rahman

2000-01-01

199

Asymptotic Analysis of Cross-Hole Hydraulic Tests in Fractured Granite  

E-print Network

for the interpretation of three-dimensional pneumatic well tests conducted in porous or fractured geologic media, which and pneumatic test data in fractured rocks. Of direct rele- vance to the present analysis are the typeAsymptotic Analysis of Cross-Hole Hydraulic Tests in Fractured Granite by Walter A. Illman1

Daniels, Jeffrey J.

200

Vertically Oriented Femoral Neck Fractures: Mechanical Analysis of Four Fixation Techniques  

Microsoft Academic Search

Objective: Femoral neck fractures inyoung individuals are typically high angled shear fractures. These injuries are difficult to stabilize due to a strong varus displacement force across the hip with weight bearing. The purpose of this study was to compare the biomechanical stability of four differing fixation techniques for stabilizing vertical shear femoral neck fractures. Methods: Vertical femoral neck fracture stability

Arash Aminian; Fan Gao; Wasyl W. Fedoriw; Li-Qun Zhang; David M. Kalainov; Bradley R. Merk

2007-01-01

201

True vertical tooth root fracture: Case report and review  

PubMed Central

It is important for the clinician not only to gather as much information about a case as possible, but also to be able to correctly interpret the data to arrive at an accurate diagnosis. Occasionally, a case presents with symptoms that might be suggestive of a condition; however, the final diagnosis may be totally different. This paper reports on an interesting case of a true vertical root fracture, in an intact maxillary molar in a 55-year-old man. The case was misdiagnosed and treated as a periodontal defect for over two months. The paper discusses the various causes and diagnostic dilemmas of root fractures. PMID:22090779

Bhaskar, U.; Logani, A.; Shah, Naseem

2011-01-01

202

Shallow hydraulic fracturing measurements in Korea support tectonic and seismic indicators of regional stress.  

SciTech Connect

We have conducted five hydraulic fracturing stress measurement campaigns in Korea, involving 13 test holes ranging in depth from 30 to 250 m, at locations from North Seoul to the southern coast of the peninsula. The measurements reveal consistent crustal stress magnitudes and directions that suggest persistence throughout western and southern Korea. The maximum horizontal stress {sigma}{sub H} is oriented between ENE-WSW and E-W, in accord with plate movement and deformation, and with directions indicated by both focal mechanism solutions from earthquakes inland and offshore as well as borehole breakouts in mainland China close to its eastern coast. With respect to magnitudes, the vertical stress is the overall minimum stress at all tested locations, suggesting a thrust faulting regime within the relatively shallow depths reached by our tests. Typically, such a stress regime becomes one favoring strike-slip at greater depths, as is also indicated by the focal mechanism solutions around Korea.

Haimson, Bezalel Cecil (University of Wisconsin, Madison, WI); Lee, Moo Yul; Song, I. (Ruhr-University Bochum, Bochum, Germany)

2003-07-01

203

Preliminary stress measurements in central California using the hydraulic fracturing technique  

USGS Publications Warehouse

Use of the hydraulic fracturing technique for determining in situ stress is reviewed, and stress measurements in wells near the towns of Livermore, San Ardo, and Menlo Park, California are described in detail. In the Livermore well, four measurements at depths between 110 and 155 m indicate that the least principal compressive stress is horizontal and increases from 1.62 to 2.66 MPa. The apparent direction of maximum compression is N 70?? E (??40??). At the San Ardo site the least principal stress is that due to the overburden weight. At depths of 240.2 and 270.7 m the minimum and maximum horizontal stresses are estimated to be 11.4 and 22.5 MPa, and 12.0 (??1.1) and 15.8 (??3.3) MPa, respectively. From an impression of the fracture at 240.2 m, the direction of maximum compression appears to be about N 15?? E. The rock in the Menlo Park well is too highly fractured to yield a reliable measurement of the horizontal stresses. The data indicate, however, that the least principal stress is vertical (due to the overburden weight) to a depth of 250 m. ?? 1977 Birkha??user Verlag.

Zoback, M.D.; Healy, J.H.; Roller, J.C.

1977-01-01

204

Inverse modeling of hydraulic tests in fractured crystalline rock based on a transition probability geostatistical approach  

NASA Astrophysics Data System (ADS)

This paper presents numerical simulations of a series of hydraulic interference tests conducted in crystalline bedrock at Olkiluoto (Finland), a potential site for the disposal of the Finnish high-level nuclear waste. The tests are in a block of crystalline bedrock of about 0.03 km3 that contains low-transmissivity fractures. Fracture density, orientation, and fracture transmissivity are estimated from Posiva Flow Log (PFL) measurements in boreholes drilled in the rock block. On the basis of those data, a geostatistical approach relying on a transitional probability and Markov chain models is used to define a conceptual model based on stochastic fractured rock facies. Four facies are defined, from sparsely fractured bedrock to highly fractured bedrock. Using this conceptual model, three-dimensional groundwater flow is then simulated to reproduce interference pumping tests in either open or packed-off boreholes. Hydraulic conductivities of the fracture facies are estimated through automatic calibration using either hydraulic heads or both hydraulic heads and PFL flow rates as targets for calibration. The latter option produces a narrower confidence interval for the calibrated hydraulic conductivities, therefore reducing the associated uncertainty and demonstrating the usefulness of the measured PFL flow rates. Furthermore, the stochastic facies conceptual model is a suitable alternative to discrete fracture network models to simulate fluid flow in fractured geological media.

Blessent, Daniela; Therrien, René; Lemieux, Jean-Michel

2011-12-01

205

Performance of petroleum reservoirs containing random vertical fractures  

E-print Network

PERFORMANCE OF PETROLEUM RESERVOIRS CONTAINING RANDOM VERTICAL FRACTURES A Thesis By WILLIAM LYMAN HUSKEY Approved as to style and content by: Chairxnan o Coxnxnittee ead of Departxnent PERFORMANCE OF PETROLEUM RESERVOIRS CONTAINING RANDOM...: Petroleum Engineering TABLE OF CONTENTS Page SUMMARY Z. INTRODUCTION . 3. EQUIPMENT AND PROCEDURE 4. PRESENTATION AND DISCUSSION OF RESULTS 5. CONCLUSIONS 6. ACKNOWLEDGMENTS . . 44 7. REFERENCES 8. BIBLIOGRAPHY . 47 TABLE QF GRAPHS AND FIGURES...

Huskey, William Lyman

2012-06-07

206

Vertical arrays for fracture mapping in geothermal systems  

SciTech Connect

In collaboration with UNOCAL Geothermal Operations, Los Alamos National Laboratory assessed the feasibility of using vertical arrays of borehole seismic sensors for mapping of microseismicity in The Geysers geothermal field. Seismicity which arises from minute displacements along fracture or fault surfaces has been shown in studies of seismically active oil reservoirs to be useful in identifying fractures affected by and possibly contributing to production. Use of retrievable borehole seismic packages at The Geysers was found to reduce the threshold for detection of microearthquakes by an estimated 2--3 orders of magnitude in comparison to surface-based sensors. These studies led to the design, materials selection, fabrication, and installation of a permanent array of geophones intended for long term seismic monitoring and mapping of fractures in the vicinity of the array at The Geysers.

Albright, J.N. [Los Alamos National Lab., NM (United States); Rutledge, J.T.; Fairbanks, T.D. [Nambe Geophysics, Inc. (United States); Thomson, J.C. [Lithos Inc. (United States); Stevenson, M.A. [Petroleum Geo-Services (United States)

1998-12-01

207

In Situ Stress Measurements Using Hydraulic Fracturing Method in a Potential Geothermal Site, Seokmo Island, South Korea  

NASA Astrophysics Data System (ADS)

We conduct hydraulic fracturing tests in a 400 m deep test hole at a potential granitic geothermal site in Seokmo Island, South Korea, and analyze the magnitude of maximum horizontal principal stress (SHmax) on the basis of Hubbert and Willis (1957) classical formula given in terms of tensile strength as an important parameter. Since the accuracy of tensile strength for the interpretation of hydraulic fracturing test data is directly related to the accuracy of SHmax, it is essential to investigate the reliability and suitability of laboratory tensile strength (T) measurements for an appropriate data interpretation in hydraulic fracturing tests. We conduct two different types of tensile strength tests (hollow cylinder tests and Brazilian tests) using various loading (or pressurization) rates (R) to find tensile strengths appropriate for the interpretation of hydraulic fracturing test results. Laboratory experimental data show that tensile strength depends significantly on loading rate and size, yielding some generalized T-log(R) as well as T-size relations, from which we estimate T values suitable for hydraulic fracturing in situ tests. SHmax directions estimated from hydraulic fracture azimuths are NE-SW (at depths <300m) and ENE-WSW (at >300m). The deeper stress direction is consistent with that of tectonic stress from earthquake focal mechanisms and borehole breakouts. The shallow stress direction appears to be interfered by topography effect due to a nearby ridge. The estimated Shmin and SHmax magnitudes down to 400 m depths are higher than vertical stress, indicating a reverse faulting favored stress regime. There is a marked fluctuation in SHmax with depth. Interestingly, some SHmax are close to the stress constrained by fractures/faults with fractional coefficient (?) equal to 1.0, and some close to that constrained by ?=0.6. We interpret that a possible source responsible for the observed fluctuation in SHmax is due to stress release by shear slip along natural fractures. The borehole penetrates numerous natural fractures and joints with variable apertures (as observed from the BHTV image). Especially some fractures with wide apertures (say, >10 mm on BHTV image) were often cored with no complete recovery of infilling material. This indicates, as we infer, that the infilling material might be clay gouges or crushed rock fragments. Such natural discontinuities with wide apertures would have relatively low frictional coefficients. Fractures with such wide apertures penetrated by the borehole is relatively abundant around the depths of relatively low SHmax (i.e., close to ?=0.6 line), while such natural fractures are scarce at depths of relatively high SHmax (i.e., close to ?=1.0 line). More importantly, those fractures with wide apertures are oriented optimally for slip under the current in situ stress conditions, playing a role of limiting stress magnitudes by slippage along the fractures and consequent release of excessive stress. Our study demonstrates that stress magnitudes can be constrained by natural fractures quite locally at a scale of few tens of meters.

Jo, Y.; Chang, C.

2013-12-01

208

Usefulness of flux measurements during hydraulic tomographic survey for mapping hydraulic conductivity distribution in a fractured medium  

NASA Astrophysics Data System (ADS)

Using the first-order analysis, we investigate the spatial cross-correlation between hydraulic conductivity variation and specific discharge (flux) as well as its components measured in a borehole under steady-state flow conditions during cross-hole pumping tests in heterogeneous aquifers. These spatial correlation patterns are found to be quite different from that between the hydraulic conductivity variation and the hydraulic head measurement in the same borehole. This finding suggests that a specific discharge measurement carries non-redundant information about the spatial distribution of heterogeneity, even this measurement is collected from the same location where the head measurement is taken. As such, specific discharge observations should be included in the analysis of hydraulic tomography to increase the resolution of estimated aquifer heterogeneity. Using numerical experiments, we demonstrate the effectiveness of the joint interpretation of both hydraulic heads and fluxes for mapping fracture distributions in a hypothetic geologic medium.

Zha, Yuanyuan; Yeh, Tian-Chyi Jim; Mao, Deqiang; Yang, Jinzhong; Lu, Wenxi

2014-09-01

209

Hydraulic interactions between fractures and bedding planes in a carbonate aquifer studied by means of experimentally induced water-table fluctuations (Coaraze  

E-print Network

1 Hydraulic interactions between fractures and bedding planes in a carbonate aquifer studied. Keywords: Karst, hydrogeochemistry, fractured rocks, hydraulic properties, France insu-00376151,version1 high and low permeability regions are controlled by the hydraulic head gradient. Past studies have

Boyer, Edmond

210

Risk assessment of groundwater contamination from hydraulic fracturing fluid spills in Pennsylvania  

E-print Network

Fast-paced growth in natural gas production in the Marcellus Shale has fueled intense debate over the risk of groundwater contamination from hydraulic fracturing and the shale gas extraction process at large. While several ...

Fletcher, Sarah Marie

2012-01-01

211

Integrated Hydraulic Fracture Placement and Design Optimization in Unconventional Gas Reservoirs  

E-print Network

Unconventional reservoir such as tight and shale gas reservoirs has the potential of becoming the main source of cleaner energy in the 21th century. Production from these reservoirs is mainly accomplished through engineered hydraulic fracturing...

Ma, Xiaodan

2013-12-10

212

Evaluation of massive hydraulic fracturing experiments in the Devonian Shales in Lincoln County, West Virginia  

E-print Network

as to style and content by: W. J. Lee (Chair of Committee) S. A. Holditch (Member) David Dubofsk (Nember) W. D, Von Gonten (Head of Department) May 1987 ABSTRACT Evaluation of Massive Hydraulic Fracturing Experiments in the Devonian Shales...

Holgate, Karen Elaine

2012-06-07

213

A qualitative analysis of non-Darcy flow effects in hydraulically fractured gas wells  

E-print Network

A QUALITATIVE ANALYSIS OF NON-DARCY FLOW EFFECTS IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by JOANNE CAROL HRESKO Submitted to the Graduate College of Texas A 5 M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1985 Major Subject: Petroleum Engineering A QUALITATIVE ANALYSIS OF NON-DARCY FLOW EFFECTS IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by JOANNE CAROL HRESKO Approved as to style and content by: W. J. Lee (Chairman...

Hresko, Joanne Carol

2012-06-07

214

Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations  

E-print Network

are complicated. Standard fracture conductivity measurement procedures were developed for high concentration propped fractures and need to be modified to measure the conductivity of unpropped fractures and the low concentration proppant packs. Water-based...

Zhang, Junjing

2014-07-10

215

Selective oxidation of bromide in wastewater brines from hydraulic fracturing.  

PubMed

Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (~1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatment processes for bromide removal is costly and not specific. Selective bromide removal is technically challenging due to the presence of other ions in the brine, especially chloride as high as 30-200 g/L. This study evaluates the ability of solid graphite electrodes to selectively oxidize bromide to bromine in flowback water and produced water from a shale gas operation in Southwestern PA. The bromine can then be outgassed from the solution and recovered, as a process well understood in the bromine industry. This study revealed that bromide may be selectively and rapidly removed from oil and gas brines (~10 h(-1) m(-2) for produced water and ~60 h(-1) m(-2) for flowback water). The electrolysis occurs with a current efficiency between 60 and 90%, and the estimated energy cost is ~6 kJ/g Br. These data are similar to those for the chlor-alkali process that is commonly used for chlorine gas and sodium hydroxide production. The results demonstrate that bromide may be selectively removed from oil and gas brines to create an opportunity for environmental protection and resource recovery. PMID:23726709

Sun, Mei; Lowry, Gregory V; Gregory, Kelvin B

2013-07-01

216

Development of an Advanced Hydraulic Fracture Mapping System  

SciTech Connect

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 analysis 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.

Norm Warpinski; Steve Wolhart; Larry Griffin; Eric Davis

2007-01-31

217

Mechanical and hydraulic behavior of a rock fracture under shear deformation  

NASA Astrophysics Data System (ADS)

With regard to crystalline rock that constitutes deep geology, attempts have been made to explore its hydraulic characteristics by focusing on the network of numerous fractures within. As the hydraulic characteristics of a rock are the accumulation of hydraulic characteristics of each fracture, it is necessary to develop the hydraulic model of a single fracture to predict the large-scale hydraulic behavior. To this end, a simultaneous permeability and shear test device is developed, and shear-flow coupling tests are conducted on specimens having fractures with varied levels of surface roughness in the constant normal stiffness conditions. The results show that the permeability characteristics in the relation between shear displacement and transmissivity change greatly at the point where the stress path reaches the Mohr-Coulomb failure curve. It is also found that there exists a range in which transmissivity is not proportional to the cube of mechanical aperture width, which seems to be because of the occurrence of channeling phenomenon at small mechanical aperture widths. This channeling flow disappears with increasing shear and is transformed into a uniform flow. We develop a simulation technique to evaluate the macroscopic permeability characteristics by the lattice gas cellular automaton method, considering the microstructure of fracture, namely the fracture surface roughness. With this technique, it is shown that the formation of the Hagen-Poiseuille flow is affected by the fracture microstructure under shear, which as a result determines the relationship between the mechanical aperture width and transmissivity.

Nishiyama, Satoshi; Ohnishi, Yuzo; Ito, Hisao; Yano, Takao

2014-12-01

218

692 E. SIEBRITS AND A. P. PEIRCE Most hydraulic fracturing simulators use a single value for Young's modulus and Poisson's  

E-print Network

#12;692 E. SIEBRITS AND A. P. PEIRCE Most hydraulic fracturing simulators use a single value of the layered reservoir that are hydraulically fractured. Some simulators use various approximate techniques (e less accurate ones) can lead to signiÿcant errors in fracture width predic- tion in cases where elastic

Peirce, Anthony

219

Submitted to WRR 1 Use of hydraulic tests at different scales to characterize fracture network properties in  

E-print Network

Submitted to WRR 1 Use of hydraulic tests at different scales to characterize fracture network, hydraulic conductivity, fracture, anisotropy 1. INTRODUCTION Hard rocks and their associated aquifers occur properties in the weathered-fractured layer of a hard rock aquifer J.C. Maréchala,b* , B. Dewandela , K

Boyer, Edmond

220

A comparison between a semi-analytical and a numerical solution of a two-dimensional hydraulic fracture  

Microsoft Academic Search

This paper compares a semi-analytical self-similar solution of the problem of a hydraulically driven fracture with results obtained using the numerical model Loramec. The problem under consideration is a hydraulic fracture propagating in an infinite impermeable elastic medium under plane strain conditions. The fracture is driven by an incompressible Newtonian fluid injected, at a constant rate, from a source located

R. Carbonell; Jean Desroches; Emmanuel Detournay

1999-01-01

221

Diffraction of seismic waves by cracks with application to hydraulic fracturing  

Microsoft Academic Search

The authors describe a method of modeling seismic waves interacting with single liquid-filled large cracks based on the Kirchhoff approximation and then apply it to field data in an attempt to estimate the size of a hydraulic fracture. They first present the theory of diffraction of seismic waves by fractures using a Green`s function representation and then compute the scattered

Enru Liu; S. Crampin; J. A. Hudson

1997-01-01

222

On the form and stability of open hydraulic fractures in the earth's crust  

Microsoft Academic Search

Energy extraction from dry geothermal reservoirs can rely on large hydraulic fractures at depth at relatively impermeable rock connected by inflow and outflow wells to the earth's surface; energy would be recovered by circulating a fluid through the fracture and a heat exchanger at the surface. The paper assesses the effects of linear gradients, primarily due to fluid flow, which

David D. Pollard

1976-01-01

223

An experimental investigation of hydraulic behaviour of fractures and joints in granitic rock  

Microsoft Academic Search

A method of measuring mean mechanical aperture of fractures based on gas volume balance is introduced. The effects of shear displacement and normal stress on mechanical and hydraulic behaviour of fractures are also investigated. The results obtained from tests conducted on granite samples from Olympic Dam (Central Australia) are compared with those calculated from existing shear dilation theories. It is

Z. Chen; S. P. Narayan; Z. Yang; S. S. Rahman

2000-01-01

224

In-Situ Stresses: The Predominant Influence on Hydraulic Fracture Containment  

Microsoft Academic Search

In-situ experiments, which are accessible by mineback, have been conducted to determine the parameters that control hydraulic fracture containment. These experiments demonstrate that a stress contrast between the pay zone and a bounding layer is the most important factor controlling fracture height. Material property interfaces are shown to have little effect. 19 refs.

Norman Warpinski; Richard Schmidt; David Northrop

1982-01-01

225

A new method for determining fluid flow paths during hydraulic fracturing  

SciTech Connect

Although hydraulic fracturing is a popular method for increasing the productivity of oil and gas wells, there is no direct way other than drilling additional boreholes to determine where the injected fluid has gone and thus what direction a fracture has propagated. Information about fluid flow paths is important for designing subsequent fracturing operations for nearby wells. Determining the locations and orientations of permeable fractures is also important in studies of potential toxic waste repositories where it is critical to understand fluid flow paths. We have developed a method for determining the orientations and locations of fractures along which fluid flows during hydraulic fracturing. The method is based on accurate determination of the locations of microseismic events, or microearthquakes, that accompany the hydraulic injection. By applying a pattern recognition technique to the locations of events from one hydraulic fracturing operation we find planes in the data along which we presume that the fluid has traveled. The planes determined using our method intersect the injection borehole and a second, nearby borehole, in regions where other data indicate that fractures are present.

Fehler, M.

1987-01-01

226

In situ examination of hydraulic fractures. [By mineback; three NTS experiments  

Microsoft Academic Search

Hydraulic fracture experiments were performed in Rainier Mesa at ERDA's Nevada Test Site as part of a nuclear containment study. Three fracture experiments were performed in a 4-in dia uncased hole at a nominal depth of 1400 ft in a uniform ash-fall tuff formation. Two experiments were conducted in one hole with different colored grout. The results showed the strong

L. D. Tyler; W. C. Vollendorf; D. A. Northrop

1977-01-01

227

Does hydraulic-fracturing theory work in jointed rock masses  

SciTech Connect

The hypocenter locations of micro-earthquakes (acoustic emissions) generated during fracturing typically are distributed three-dimensionally suggesting that fracturing stimulates a volumetric region, rather than the planar fracture theoretically expected. The hypocenter maps generated at six operating, or potential, HDR reservoirs in the US, Europe and Japan are examined in detail and the fracture dimensions are correlated with fracture injection volumes and formation permeability. Depsite the volumetric appearance of the maps we infer that the induced fractures are mainly planar and may propagate aseismically. The induced seismicity stems from nearby joints, which are not opened significantly by fracturing, but are caused to shear-slip because of local pore pressure.

Murphy, H.D.; Keppler, H.; Dash, Z.V.

1983-01-01

228

Water sources and disposal related to hydraulic fracturing in the Barnett Shale: a historical perspective  

NASA Astrophysics Data System (ADS)

During the past few years, hydraulic fracturing (HF) has become a hotly debated topic particularly related to volume of water used and potential for contamination of shallow aquifers. In this communication, we focused on water use in the oldest shale play in the world as an example for an analysis of historical patterns of water use, consumption, and disposal. The Barnett Shale play in Texas provides an ideal case to assess some of the issues related to shale gas production. It was the first shale play to submit to intense slick-water HF (first horizontal wells in 2003, ~15,000 horizontal wells completed to date). An estimated 200, 000 acre-feet (247 million m3) of water has been used so far in the play (included for vertical wells), mostly in the 4-5 counties making up the core area. More than 90% of the water used is consumed and relatively little recycling occurs in the play. Most of the flowback / produced water is disposed of through injection wells. The median Barnett horizontal well produces back ~100% of the amount of water injected for fracturing in the course of the few years following completion, an amount larger than other well-known shale gas plays. The communication will provide detailed material documenting these findings.

Nicot, J.; Scanlon, B. R.

2013-12-01

229

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

SciTech Connect

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 was 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.

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

1996-12-31

230

Microearthquakes induced during hydraulic fracturing at the Fenton Hill HDR site: the 1982 experiments  

SciTech Connect

The on-site real-time processing of microearthquake signals that occur during massive hydraulic fracturing provides a notion of the location and growth of the fracture system being created. This enables quick decisions to be made in regard to the ongoing operations. The analytical results and impact of the hypocenter mapping during the 1982 fracturing experiments in the Fenton Hill Phase II Hot Dry Rock geothermal reservoir are reported.

Keppler, H.; Pearson, C.F.; Potter, R.M.; Albright, J.N.

1983-01-01

231

Crosswell seismic investigation of hydraulically conductive, fracture bedrock near Mirror Lake, New Hampshire  

USGS Publications Warehouse

Near Mirror Lake, New Hampshire (USA), hydraulically conductive, fractured bedrock was investigated with the crosswell seismic method to determine whether this method could provide any information about hydraulic conductivity between wells. To this end, crosswell seismic data, acoustic logs from boreholes, image logs from boreholes, and single borehole hydraulic tests were analyzed. The analysis showed that, first, the P-wave velocities from the acoustic logs tended to be higher in schist than they were in granite. (Schist and granite were the dominant rock types). Second, the P-wave velocities from the acoustic logs tended to be low near fractures. Third, the hydraulic conductivity was always low (always less than to 10-8 m/s) where no fractures intersected the borehole, but the hydraulic conductivity ranged from low to high (from less than to 10-10 m/s to 10-4 m/s) where one or more fractures intersected the borehole. Fourth, high hydraulic conductivities were slightly more frequent when the P-wave velocity was low (less than 5200 m/s) than when it was high (greater than or equal to 5200 m/s). The interpretation of this statistical relation was that the fractures tended to increase the hydraulic conductivity and to lower the P-wave velocity. This statistical relation was applied to a velocity tomogram to create a map showing the probability of high hydraulic conductivity; the map was consistent with results from independent hydraulic tests. ?? 2002 Elsevier Science B.V. All rights reserved.

Ellefsen, K.J.; Hsieh, P.A.; Shapiro, A.M.

2002-01-01

232

Vertical cross contamination of trichloroethylene in a borehole in fractured sandstone  

USGS Publications Warehouse

Boreholes drilled through contaminated zones in fractured rock create the potential for vertical movement of contaminated ground water between fractures. The usual assumption is that purging eliminates cross contamination; however, the results of a field study conducted in a trichloroethylene (TCE) plume in fractured sandstone with a mean matrix porosity of 13% demonstrates that matrix-diffusion effects can be strong and persistent. A deep borehole was drilled to 110 m below ground surface (mbgs) near a shallow bedrock well containing high TCE concentrations. The borehole was cored continuously to collect closely spaced samples of rock for analysis of TCE concentrations. Geophysical logging and flowmetering were conducted in the open borehole, and a removable multilevel monitoring system was installed to provide hydraulic-head and ground water samples from discrete fracture zones. The borehole was later reamed to complete a well screened from 89 to 100 mbgs; persistent TCE concentrations at this depth ranged from 2100 to 33,000 ??g/L. Rock-core analyses, combined with the other types of borehole information, show that nearly all of this deep contamination was due to the lingering effects of the downward flow of dissolved TCE from shallower depths during the few days of open-hole conditions that existed prior to installation of the multilevel system. This study demonstrates that transfer of contaminant mass to the matrix by diffusion can cause severe cross contamination effects in sedimentary rocks, but these effects generally are not identified from information normally obtained in fractured-rock investigations, resulting in potential misinterpretation of site conditions. Copyright ?? 2005 National Ground Water Association.

Sterling, S.N.; Parker, B.L.; Cherry, J.A.; Williams, J.H.; Lane, J.W., Jr.; Haeni, F.P.

2005-01-01

233

Public perceptions on fresh water use for hydraulic fracturing of the Duvernay Shale Gas Formation, Kaybob Area, Alberta.  

E-print Network

??The thesis research examined localized socio-environmental perceptions related to amplified fresh water requirements for hydraulic fracturing and subsequent flowback disposal activities. These requirements are associated… (more)

Jobson, Emily

2013-01-01

234

Seismic imaging of hydraullically-stimulated fractures: A numerical study of the effect of the source mechanism  

E-print Network

We present a numerical study of seismic imaging of hydraulically stimulated fractures using a single source from an adjacent fracturing-process. The source is either a point force generated from the perforation of the ...

Shabelansky, Andrey Hanan

2012-01-01

235

77 FR 40354 - Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel Fuels-Draft  

Federal Register 2010, 2011, 2012, 2013, 2014

...operations related to oil, gas, or geothermal production activities'' (SDWA Section...fracturing related to oil, gas, or geothermal operations must obtain a UIC permit...references hydraulic fracturing related to geothermal activities, the draft guidance...

2012-07-09

236

Simulation of the hydraulic fracture process in two dimensions using a discrete element method.  

PubMed

We introduce a discrete element simulation for the hydraulic fracture process in a petroleum well which takes into account the elastic behavior of the rock and the Mohr-Coulomb fracture criterium. The rock is modeled as an array of Voronoi polygons joined by elastic beams, which are submitted to tectonical stresses and the hydrostatic pressure of the fracturing fluid. The fluid pressure is treated like that of a hydraulic column. The simulation reproduces well the time and dimensions of real fracture processes. We also include an analysis of the fracturing fluid loss due to the permeability of the rock which is useful in an efficiency analysis of the treatment. The model is a first step for future applications in the petroleum industry. PMID:17677327

Torres, Sergio Andres Galindo; Castaño, Jose Daniel Muñoz

2007-06-01

237

Fracture prediction in hydraulic bulging of AISI 304 austenitic steel sheets based on a modified ductile fracture criterion  

NASA Astrophysics Data System (ADS)

The demand for weight reduction in modern vehicle construction has resulted in an increase in the application of hydroforming processes for the manufacture of automotive lightweight components. This trend led to the research of evaluation on formability of the sheet or tube hydroforming to be noted, particularly the prediction of fracture. In this study, a new proposed approach based on damage theory for fracture prediction considering the deformation history was introduced. And the modified ductile fracture criterion was applied to predict the failure for hydraulic bulging of AISI 304 austenitic steel sheets. The material parameters in terms of the function of strain rate in the failure criterion were determined from the equivalent fracture strains corresponding tensile tests under different stress conditions. Then, in the finite element simulation the effect of strain rates and their distribution as well during practical sheet metal forming process was considered. The hydraulic bulging tests were carried out to identify the fracture behavior predicted from FE analysis. A comparison between the prediction and experimental results showed that the proposed approach with a modified ductile fracture criteria can give better fracture predictions than traditional ways.

Xu, Y.; Song, H. W.; Zhang, S. H.; Cheng, M.

2011-08-01

238

Hydraulic anisotropy characterization of pneumatic-fractured sediments using azimuthal self potential gradient.  

PubMed

The pneumatic fracturing technique is used to enhance the permeability and porosity of tight unconsolidated soils (e.g. clays), thereby improving the effectiveness of remediation treatments. Azimuthal self potential gradient (ASPG) surveys were performed on a compacted, unconsolidated clay block in order to evaluate their potential to delineate contaminant migration pathways in a mechanically-induced fracture network. Azimuthal resistivity (ARS) measurements were also made for comparative purposes. Following similar procedures to those used in the field, compressed kaolinite sediments were pneumatically fractured and the resulting fracture geometry characterized from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. We subsequently injected a simulated treatment (electrolyte/dye) into the fractures. Both ASPG and ARS data exhibit anisotropic geoelectric signatures resulting from the fracturing. Self potentials observed during injection of electrolyte are consistent with electrokinetic theory and previous laboratory results on a fracture block model. Visual (polar plot) analysis and linear regression of cross plots show ASPG lobes are correlated with azimuths of high fracture strike density, evidence that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. However, ARS data are uncorrelated with fracture strike maxima and resistivity anisotropy is probably dominated by enhanced surface conduction along azimuths of weak 'starter paths' formed from pulverization of the clay and increases in interfacial surface area. We find the magnitude of electrokinetic SP scales with the applied N2 gas pressure gradient (DeltaPN2) for any particular hydraulically-active fracture set and that the positive lobe of the ASPG anomaly indicates the flow direction within the fracture network. These findings demonstrate the use of ASPG in characterizing the effectiveness of (1) pneumatic fracturing and (2) defining likely flow directions of remedial treatments in unconsolidated sediments and rock. PMID:19070400

Wishart, DeBonne N; Slater, Lee D; Schnell, Deborah L; Herman, Gregory C

2009-01-26

239

Particle-based simulation of hydraulic fracture and fluid/heat flow in geothermal reservoirs  

NASA Astrophysics Data System (ADS)

Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet's future energy demands that a key geophysical problem be solved first: how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle - the coupling of the Lattice Solid Model (LSM) to simulate the nonlinear dynamics of complex solids with the Lattice Boltzmann Method (LBM) applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fracturing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge-or powder-filled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.

Mora, Peter; Wang, Yucang; Alonso-Marroquin, Fernando

2013-06-01

240

Onset of Hydraulic Fracture Initiation Monitored by Acoustic Emission and Volumetric Deformation Measurements  

NASA Astrophysics Data System (ADS)

In this paper, the results of laboratory studies of fracture initiation, early propagation and breakdown are reported. Three experiments were conducted on a low permeability sandstone block, loaded in a polyaxial test frame, to representative effective in situ stress conditions. The blocks were instrumented with acoustic emission (AE) and volumetric deformation sensors. In two experiments, fluids of different viscosity were injected into the wellbore, fluid injection was interrupted soon after the breakdown pressure had been reached. This allowed us to investigate hydraulic fracture initiation. In the third test, fracture initiation criteria were applied to stop hydraulic fracture propagation significantly earlier, prior to breakdown, and as it propagated a short distance from the wellbore. The analysis of AE results shows an increase in AE activity and a change in the AE spatial correlation, during the fracture initiation. This early stage of fracturing correlates strongly with the onset of rock volumetric deformation, and is confirmed by the analysis of ultrasonic transmission monitoring. The rock microstructure, after the test, was investigated by analysis of scanning electron microscope images. These indicated the development of leak-off zone near the wellbore and a dry hydraulic fracture at the farther distance from the wellbore.

Stanchits, Sergey; Surdi, Aniket; Gathogo, Patrick; Edelman, Eric; Suarez-Rivera, Roberto

2014-09-01

241

Using flowmeter pulse tests to define hydraulic connections in the subsurface: A fractured shale example  

USGS Publications Warehouse

Cross-borehole flowmeter pulse tests define subsurface connections between discrete fractures using short stress periods to monitor the propagation of the pulse through the flow system. This technique is an improvement over other cross-borehole techniques because measurements can be made in open boreholes without packers or previous identification of water-producing intervals. The method is based on the concept of monitoring the propagation of pulses rather than steady flow through the fracture network. In this method, a hydraulic stress is applied to a borehole connected to a single, permeable fracture, and the distribution of flow induced by that stress monitored in adjacent boreholes. The transient flow responses are compared to type curves computed for several different types of fracture connections. The shape of the transient flow response indicates the type of fracture connection, and the fit of the data to the type curve yields an estimate of its transmissivity and storage coefficient. The flowmeter pulse test technique was applied in fractured shale at a volatile-organic contaminant plume in Watervliet, New York. Flowmeter and other geophysical logs were used to identify permeable fractures in eight boreholes in and near the contaminant plume using single-borehole flow measurements. Flowmeter cross-hole pulse tests were used to identify connections between fractures detected in the boreholes. The results indicated a permeable fracture network connecting many of the individual boreholes, and demonstrated the presence of an ambient upward hydraulic-head gradient throughout the site.

Williams, J.H.; Paillet, F.L.

2002-01-01

242

Pore-fluid effects on seismic waves in vertically fractured earth with orthotropic symmetry  

SciTech Connect

For elastically noninteracting vertical-fracture sets at arbitrary orientation angles to each other, a detailed model is presented in which the resulting anisotropic fractured medium generally has orthorhombic symmetry overall. Some of the analysis methods and ideas of Schoenberg are emphasized, together with their connections to other similarly motivated and conceptually related methods by Sayers and Kachanov, among others. Examples show how parallel vertical-fracture sets having HTI (horizontal transversely isotropic) symmetry transform into orthotropic fractured media if some subsets of the vertical fractures are misaligned with the others, and then the fractured system can have VTI (vertical transversely isotropic) symmetry if all of the fractures are aligned randomly or half parallel and half perpendicular to a given vertical plane. An orthotropic example having vertical fractures in an otherwise VTI earth system (studied previously by Schoenberg and Helbig) is compared with the other examples treated and it is finally shown how fluids in the fractures affect the orthotropic poroelastic system response to seismic waves. The key result is that fracture-influence parameters are multiplied by a factor of (1-B), where 0 {le} B < 1 is Skempton's second coefficient for poroelastic media. Skempton's B coefficient is itself a measurable characteristic of fluid-saturated porous rocks, depending on porosity, solid moduli, and the pore-fluid bulk modulus. For heterogeneous porous media, connections between the present work and earlier related results of Brown and Korringa are also established.

Berryman, J.G.

2010-05-15

243

Hydraulic fracturing in a sedimentary geothermal reservoir: Results and implications  

Microsoft Academic Search

Field experiments in a geothermal research well were conducted to enhance the inflow performance of a clastic sedimentary reservoir section. Due to depths exceeding 4050m, bottom hole temperatures exceeding 140°C, and open hole section (dual zone), technically demanding and somewhat unprecedented conditions had to be managed. The fracturing operations were successful. Fractures were created in two isolated borehole intervals and

B. Legarth; E. Huenges; G. Zimmermann

2005-01-01

244

Final Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources (02-24-2012)  

EPA Science Inventory

The overall purpose of this study is to elucidate the relationship, if any, between hydraulic fracturing and drinking water resources. More specifically, the study has been designed to assess the potential impacts of hydraulic fracturing on drinking water resources and to identif...

245

IDENTIFYING HYDRAULICALLY CONDUCTIVE FRACTURES WITH A SLOW-VELOCITY BOREHOLE FLOWMETER.  

USGS Publications Warehouse

The U. S. Geological Survey used a recently developed heat-pulse flowmeter to measure very slow borehole axial water velocities in granitic rock at a site near Lac du Bonnet, Manitoba, Canada. The flowmeter was used with other geophysical measurements to locate and identify hydraulically conducting fractures contributing to the very slow vertical water flow in the two boreholes selected for study. The heat-pulse flowmeter has a flow-measuring range in water of 0. 06-6m/min, and can resolve velocity differences as slow as 0. 01 m/min. This is an order of magnitude slower than the stall speed of spinner flowmeters. The flowmeter is 1. 16 m long and 44 mm in diameter. It was calibrated in columns of 76 and 152 mm diameter, to correspond to the boreholes studied. The heat-pulse flowmeter system is evaluated, and problems peculiar to the measurement of very slow axial water velocities in boreholes are discussed.

Hess, Alfred E.

1986-01-01

246

An Innovative Approach for Management of Vertical Coronal Fracture in Molar: Case Report  

PubMed Central

Unlike anterior teeth, acute exogenous trauma is an infrequent cause of posterior coronal vertical tooth fractures. Endodontic and restorative management of such fractures is a great challenge for the clinician. Newer advancements in adhesive techniques can provide successful intracoronal splinting of such teeth to reinforce the remaining tooth structure. This paper describes the diagnosis and management of a case of complicated vertical coronal fracture in mandibular first molar induced by a traffic accident. PMID:22567453

Kathuria, Ambica; Kavitha, M.; Ravishankar, P.

2012-01-01

247

Hydraulic-fracture diagnostic research. Final report, December 1989-December 1990  

SciTech Connect

The results of the research in microseismic methods to determine hydraulic fracture dimensions during the contract were significant. The GRI Hydraulic Fracture Test Site (HFTS) development planning was a major effort. Ten meetings of the Planning Team were coordinated and hosted. A statement of the HFTS mission, scope, objectives, and requirements was created. The primary objectives were to provide for interdisciplinary experiments on fracture modeling and fracture diagnostics. A Conceptual Plan for the HFTS was compiled by Teledyne Geotech and distributed at the Project Advisors Group meeting. An experiment at the Shell South Belridge Field in California was a direct analog of the HFTS. Multiple fracture stimulations were monitored from 3 wells with cemented-in geophones. Methods of handling and processing large data volumes in real time were established. The final fracture geometry did not fit the circular model. Fracture diagnostics were monitored at two GRI cooperative wells: the Enron S. Hogsback No. 13-8A and the Phillips Ward C No. 11. Theoretical studies indicate that crack waves might be used as an estimate of fracture length. After applying advanced signal enhancement techniques to low-frequency signals from 14 surveys, it was concluded that the data from presently available sondes is contaminated by sonde resonances.

Fix, J.E.; Adair, R.G.; Clawson, G.E.; Lawhorn, W.S.; Mahrer, K.D.

1992-05-01

248

Fatigue hydraulic fracturing by cyclic reservoir treatment enhances permeability and reduces induced seismicity  

NASA Astrophysics Data System (ADS)

The occurrence of induced seismic events during hydraulic fracturing of reservoirs to enhance permeability is an unavoidable process. Due to the increased public concern with respect to the risks imposed by induced seismicity, however, the development of a soft stimulation method is needed creating higher permeability with less induced seismicity. We use a discrete element model of naturally fractured rock with pore fluid flow algorithm in order to analyse two scenarios of high-pressure fluid injection (hydraulic fracturing) at depth and associated induced seismicity. The ratio of pumped-in energy to released seismic energy is in agreement with field data. Our results suggest that cyclic reservoir treatment is a safer alternative to conventional hydraulic fracture stimulation as both, the total number of induced events as well as the occurrence of larger magnitude events are lowered. This work is motivated by results of laboratory triaxial indenter tests on granite rock samples where continuous loading leads to a wide fracture process zone while cyclic treatment with frequent starting and stopping of loading fatigues the rock, resulting in smaller damage volume and more persistent fracture growth.

Zang, Arno; Yoon, Jeoung Seok; Stephansson, Ove; Heidbach, Oliver

2013-11-01

249

Diffraction of seismic waves by cracks with application to hydraulic fracturing  

SciTech Connect

The authors describe a method of modeling seismic waves interacting with single liquid-filled large cracks based on the Kirchhoff approximation and then apply it to field data in an attempt to estimate the size of a hydraulic fracture. They first present the theory of diffraction of seismic waves by fractures using a Green`s function representation and then compute the scattered radiation patterns and synthetic seismograms for fractures with elliptical and rectangular shapes of various dimensions. It is shown that the characteristics of the diffracted wavefield from single cracks are sensitive to both crack size and crack shape. Finally, they compare synthetic waveforms to observed waveforms recorded during a hydraulic fracturing experiment and are able to predict successfully the size of a hydraulically induced fracture (length and height). In contrast to previously published work based on the Born approximation, the authors model both phases and amplitudes of observed diffracted waves. The modeling has resulted in an estimation of a crack length 1.1 to 1.5 times larger than previously predicted, whereas the height remains essentially the same as that derived using other techniques. This example demonstrates that it is possible to estimate fracture dimensions by analyzing diffracted waves.

Liu, E. [British Geological Survey, Edinburgh (United Kingdom)] [British Geological Survey, Edinburgh (United Kingdom); Crampin, S. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics] [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics; Hudson, J.A. [Univ. of Cambridge (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics] [Univ. of Cambridge (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics

1997-01-01

250

A Study of Hydraulic Fracturing Initiation in Transversely Isotropic Rocks  

E-print Network

fractures and also can be used to develop information about in-situ rock properties using failure pressure values observed in the field. Finally, mechanical and permeability anisotropy are measured using Pulse Permeameter and triaxial tests on Pierre shale....

Serajian, Vahid

2011-10-21

251

The evolution of hydraulic fracturing in the Almond formation  

SciTech Connect

This study draws from a database of over 600 wells to evaluate reservoir, production and treatment characteristics in the low-permeability, naturally-fractured Almond formation. Treatment-induced damage can be significant; damage mechanisms are discussed and ways are shown to mitigate these problems. An effective fracture stimulation design combines proppant scheduling of the late 1970`s with fluid and gel-breaker systems of today.

Cramer, D.D.

1995-12-31

252

Test Design and Sample Preparation Procedure for Experimental Investigation of Hydraulic Fracturing Interaction Modes  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing is a complex operation which is influenced by several factors including the formation properties, state of stresses in the field, injecting fluid and pumping rate. Before carrying out the expensive fracturing operation in the field, it would be useful to understand the effect of various parameters by conducting physical experiments in the laboratory. Also, laboratory experiments are valuable for validating numerical simulations. For this purpose, laboratory experiments may be conducted on synthetically made samples to study the effect of various parameters before using real rock samples, which may not be readily available. To simulate the real stress conditions in the field, experiments need to be conducted on cube-shaped samples on which three independent stresses can be applied. The hydro-mechanical properties of a sample required for modelling purposes and the design of a scaled hydraulic fracturing test in the laboratory can be estimated by performing various laboratory experiments on cylindrical plugs. The results of laboratory experiments are scaled to field operation by applying scaling laws. In this paper, the steps to prepare a cube-shaped mortar sample are explained. This follows a review of the sample set-up procedure in a true tri-axial stress cell for hydraulic fracturing experiments. Also, the minimum tests on cylindrical plugs required to estimate the hydro-mechanical properties of the rock sample are explained. To simulate the interaction mode when a hydraulic fracture approaches an interface in the laboratory, the procedure for producing samples with parallel artificial fracture planes is explained in this paper. The in-fill material and the angle of fracture planes were changed in different samples to investigate the effect of interface cohesion and the angle of approach on the interaction mechanism.

Sarmadivaleh, M.; Rasouli, V.

2015-01-01

253

A Hermite cubic collocation scheme for plane strain hydraulic fractures Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2  

E-print Network

A Hermite cubic collocation scheme for plane strain hydraulic fractures A. Peirce Department Accepted 13 February 2010 Available online 4 March 2010 Keywords: Hydraulic fractures Integro the propagation of a hydraulic fracture in a state of plane strain. Special blended cubic Hermite-power­law basis

Peirce, Anthony

254

Identification of Successful Practices in Hydraulic Fracturing Using Intelligent Data Mining Tools; Application to the Codell Formation in the DJ Basin  

E-print Network

SPE 77597 Identification of Successful Practices in Hydraulic Fracturing Using Intelligent Data to identify successful practices in hydraulic fracturing. The Codell formation is a low permeability sandstone candidate selection and identify successful practices. Hydraulic fracturing is an economic way of increasing

Mohaghegh, Shahab

255

A Hermite cubic collocation scheme for plane strain hydraulic fractures Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2  

E-print Network

A Hermite cubic collocation scheme for plane strain hydraulic fractures A. Peirce Department Accepted 13 February 2010 Available online xxxx Keywords: Hydraulic fractures Integro-partial differential of a hydraulic fracture in a state of plane strain. Special blended cubic Hermite-power­law basis functions

Peirce, Anthony

256

A comparison of microseismicity induced by gel-proppant-and water-injected hydraulic fractures, Carthage Cotton Valley gas field, East Texas  

E-print Network

A comparison of microseismicity induced by gel-proppant- and water-injected hydraulic fractures induced during a series of hydraulic fracture completions within the Cotton Valley formation of East Texas a series of hydraulic fracture imaging tests in the Carthage Cotton Valley gas field of East Texas (Walker

257

Risks to Water Resources from Shale Gas Development and Hydraulic Fracturing in the United States  

NASA Astrophysics Data System (ADS)

The rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded oil and gas exploration in the USA. The rapid rate of shale gas exploration has triggered an intense public debate regarding the potential environmental and human health effects. A review of the updated literature has identified four potential risks for impacts on water resources: (1) stray gas contamination of shallow aquifers near shale gas sites; (2) contamination of surface water and shallow groundwater from spills, leaks, and disposal of inadequately treated wastewater or hydraulic fracturing fluids; (3) accumulation of toxic and radioactive residues in soil or stream sediments near disposal or spill sites; and (4) over-extraction of water resources for drilling and hydraulic fracturing that could induce water shortages and conflicts with other water users, particularly in water-scarce areas. As part of a long-term research on the potential water contamination associated with shale gas development, new geochemical and isotopic techniques have been developed for delineating the origin of gases and contaminants in water resource. In particular, multiple geochemical and isotopic (carbon isotopes in hydrocarbons, noble gas, strontium, boron, radium isotopes) tracers have been utilized to distinguish between naturally occurring dissolved gas and salts in water and contamination directly induced from shale gas drilling and hydraulic fracturing operations.

Vengosh, Avner; Jackson, Robert B.; Warner, Nathaniel; Darrah, Thomas H.; Kondash, Andrew

2014-05-01

258

Environmental impact assessment: enhanced gas recovery by massive hydraulic fracturing in Lincoln County, West Virginia  

Microsoft Academic Search

The US DOE has contracted with the Columbia Gas Transmission Corp. to share the cost of a field experiment of the Massive Hydraulic Fracturing (MHF) process for natural gas recovery. The project is part of a larger program to develop reservoir stimulation techniques for natural gas within the Devonian Shale formation of the Appalachian region. The experiment will take place

Schnorr

1978-01-01

259

Hydraulic fracturing stress measurements at Yucca Mountain, Nevada, and relationship to the regional stress field  

Microsoft Academic Search

Hydraulic fracturing stress measurements and acoustic borehole televiewer logs were run in holes USW G-1 and USW G-2 at Yucca Mountain as part of the Nevada Nuclear Waste Storage Investigations for the U. S. Department of Energy. Eight tests in the saturated zone, at depths from 646 to 1288 m, yielded values of the least horizontal stress S\\/sub h\\/ that

J. M. Stock; J. H. Healy; S. H. Hickman; M. D. Zoback

1985-01-01

260

Preliminary stress measurements in central California using the hydraulic fracturing technique  

Microsoft Academic Search

Use of the hydraulic fracturing technique for determiningin situ stress is reviewed, and stress measurements in wells near the towns of Livermore, San Ardo, and Menlo Park, California are described in detail. In the Livermore well, four measurements at depths between 110 and 155 m indicate that the least principal compressive stress is horizontal and increases from 1.62 to 2.66

Mark D. Zoback; John H. Healy; John C. Roller

1977-01-01

261

Hydraulic fracturing stress measurements near the Hohenzollern-Graben-structure, SW Germany  

Microsoft Academic Search

Summary Hydraulic fracturing stress measurements have been performed in a limestone quarry near the Hohenzollern-Graben, a fault structure in SW Germany. The values of the two horizontal principal stresses were 24 and 15 bars at a depth of 25 m. The magnitude and the direction of the stresses agree with the results obtained by door-stopper measurements at the same location

F. Rummel; R. Jung

1975-01-01

262

Growth rate of a penny-shaped crack in hydraulic fracturing of rocks  

Microsoft Academic Search

The stable growth of a crack created by the hydraulic pressurizing of a penny-shaped crack in a dry rock mass is investigated. The rock mass is infinitely extended, homogeneous, and isotropic. It is verified on the basis of the equations of fluid dynamics that the fracturing fluid cannot penetrate the entire domain of a crack when the crack is moving.

H. Abé; F. T. Mura; L. M. Keer

1976-01-01

263

Identification, characterization, and analysis of hydraulically conductive fractures in granitic basement rocks, Millville, Massachusetts  

USGS Publications Warehouse

A suite of geophysical logs designed to identify and characterize fractures and water production in fractures was run in six bedrock boreholes at a ground-water contamination site near the towns of Millville and Uxbridge in south-central Massachusetts. The geophysical logs used in this study included conventional gamma, single-point resistance, borehole fluid resistivity, caliper, spontaneous potential, and temperature; and the borehole televiewer and heat-pulse flowmeter, which are not usually used to log bedrock water-supply wells. Downward flow under ambient hydraulic-head conditions was measured in three of the boreholes at the site, and the profile of fluid column resistivity inferred from the logs indicated downward flow in all six boreholes. Steady injection tests at about 1.0 gallon per minute were used to identify fractures capable of conducting flow under test conditions. Sixteen of 157 fracturesidentified on the televiewer logs and interpreted as permeable fractures in the data analysis were determined to conduct flow under ambient hydraulic-head conditions or during injection. Hydraulic-head monitoring in the bedrock boreholes indicated a consistent head difference between the upper and lower parts of the boreholes. This naturally occurring hydraulic-head condition may account, in part, for the transport of contaminants from the overlying soil into the bedrock aquifer. The downward flow may also account for the decrease in contaminant concentrations found in some boreholes after routine use of the boreholes as water-supply wells was discontinued.

Paillet, F.L.; Ollila, P.W.

1994-01-01

264

The crack tip solution for hydraulic fracturing in a permeable solid  

Microsoft Academic Search

This paper extends previous work on self-similar analytical solutions for a hydraulically driven fracture propagating in a solid which is in a state of plane strain. In particular, we examine the effect of fluid loss to the formation modelled by the Carter leak-off mechanism. Our main new results are asymptotic solutions for arbitrary rock permeability; it is shown how these

B. Lenoach

1995-01-01

265

Use of Well Logs to Provide Formation Design Values for Hydraulic Fracture Treatments  

Microsoft Academic Search

This study presnts wireline tool usage in providing proper design parameter values for hydraulic fracture treatments and in evaluating the success of such a treatment. Examples of logging suites are provided and methods are presented for converting log measurements into design values. Techniques are discussed and a matrix chart has been developed for relating tool capabilities with design requirements. It

S. Ameri; H. H. Rieke

1981-01-01

266

ANALYSIS OF GAS PRODUCTION FROM HYDRAULICALLY FRACTURED WELLS IN THE HAYNESVILLE SHALE USING SCALING METHODS  

E-print Network

ANALYSIS OF GAS PRODUCTION FROM HYDRAULICALLY FRACTURED WELLS IN THE HAYNESVILLE SHALE USING. The reservoir temperature is also high, up to 3000 F. These pressures are uniquely high among shale gas gas from the Haynesville Shale without horizontal wells and massive hydrofractures. In addition

Patzek, Tadeusz W.

267

Hydraulic fracturing tests in anhydrite interbeds in the WIPP, Marker Beds 139 and 140  

SciTech Connect

Hydraulic fracturing tests were integrated with hydrologic tests to estimate the conditions under which gas pressure in the disposal rooms in the Waste Isolation Pilot Plant, Carlsbad, NM (WIPP) will initiate and advance fracturing in nearby anhydrite interbeds. The measurements were made in two marker beds in the Salado formation, MB139 and MB140, to explore the consequences of existing excavations for the extrapolation of results to undisturbed ground. The interpretation of these measurements is based on the pressure-time records in two injection boreholes and several nearby hydrologic observation holes. Data interpretations were aided by post-test borehole video surveys of fracture traces that were made visible by ultraviolet illumination of fluorescent dye in the hydraulic fracturing fluid. The conclusions of this report relate to the upper- and lower-bound gas pressures in the WIPP, the paths of hydraulically and gas-driven fractures in MB139 and MB140, the stress states in MB139 and MB140, and the probable in situ stress states in these interbeds in undisturbed ground far away from the WIPP.

Wawersik, W.R., Carlson, L.W., Henfling, J.A., Borns, D.J., Beauheim, R.L. [Sandia National Labs., Albuquerque, NM (United States); Howard, C.L. [RE/SPEC Inc., Albuquerque, NM (United States); Roberts, R.M., [INTERA Inc., Albuquerque, NM (United States)

1997-05-01

268

Microseismic monitoring of the B-sand hydraulic fracture experiment at the DOE/GRI multi-site project  

SciTech Connect

Six hydraulic-fracture injections into a fluvial sandstone at a depth of 4500 ft were monitored with multi-level triaxial seismic receivers in two wells, resulting in maps of the growth and final geometry of each fracture based upon microseismic activity. These diagnostic images show that the hydraulic fractures are highly contained for smaller-volume KCl-water injections, but height growth is significant for the larger-volume, higher-rate, higher-viscosity treatments. Fracture lengths for most injections are similar. Final results are also compared with fracture models.

Warpinski, N.R. [SPE, Richardson, TX (United States)]|[Sandia National Lab., Albuquerque, NM (United States); Wright, T.B.; Peterson, R.E.; Branagan, P.T. [SPE, Richardson, TX (United States)] [and others

1996-11-01

269

Specific Methods for the Evaluation of Hydraulic Properties in Fractured Hard-rock J.C. Marchala,*  

E-print Network

1 Specific Methods for the Evaluation of Hydraulic Properties in Fractured Hard-rock Aquifers J, marechal@ngri.res.in Abstract: Blocs underlined by fractures networks mainly compose hard-rock aquifers. The complexity of flows through fractures makes inadequate the use of classical techniques for the interpretation

Paris-Sud XI, Université de

270

Characteristics of shut-in curves in hydraulic fracturing stress measurements and determination of in situ minimum compressive stress  

Microsoft Academic Search

Characteristics of pressure decay curves obtained after shut-in hydraulic fracturing stress measurements are studied in detail in an effort to enhance the reliability of the minimum compressive in situ stress determination. The analysis utilizes linear theory of elasticity, fracture mechanics, and global mass balance of fracturing fluid after shut-in. A small amount of crack growth takes place almost instantaneously just

Kazuo Hayashi; Bezalel C. Haimson

1991-01-01

271

In-situ stress and fracture characterization for planning of a hydraulic stimulation in the Desert Peak Geothermal Field, NV  

NASA Astrophysics Data System (ADS)

A suite of geophysical logs and a hydraulic fracturing stress measurement were conducted in well 27-15 in the Desert Peak Geothermal Field, Nevada, to constrain the state of stress and the geometry and relative permeability of natural fractures in preparation for development of an Enhanced Geothermal System (EGS) through hydraulic stimulation. Advanced Logic Technologies Borehole Televiewer (BHTV) and Schlumberger Formation MicroScanner (FMS) image logs reveal extensive drilling-induced tensile fractures, showing that the current minimum horizontal principal stress, Shmin, in the vicinity of well 27-15 is oriented 114 ± 17°. This orientation is consistent with down-dip extensional slip on a set of ESE and WNW dipping normal faults mapped at the surface. Similarly, all formations imaged in the BHTV and FMS logs include significant sub-populations of fractures that are well oriented for normal faulting given this direction of Shmin. Although the bulk permeability of the well is quite low, temperature and spinner flowmeter surveys reveal several minor flowing fractures. Some of these relatively permeable fractures are well oriented for normal faulting, in addition to fluid flow that is preferentially developed at low-angle formation boundaries. A hydraulic fracturing stress measurement conducted at the top of the intended stimulation interval (931 m) indicates that the magnitude of Shmin is 13.8 MPa, which is 0.609 of the calculated vertical (overburden) stress at this depth. Given the current water table depth (122 m below ground level), this Shmin magnitude is somewhat higher than expected for frictional failure on optimally oriented normal faults given typical laboratory measurements of sliding friction (Byerlee’s Law). Coulomb failure calculations assuming cohesionless pre-existing fractures with coefficients of friction of 0.6 or higher (consistent with Byerlee’s Law and with tests on representative core samples from nearby wells) indicate that shear failure could be induced on well-oriented fractures seen in the well once fluid pressures are increased ~2.5 MPa or more above the ambient formation fluid pressure. This includes the intended stimulation interval at 0.9 to 1.1 km depth, which is comprised of rhyolite tuff and argillite at ambient temperatures of ~180 to 195° C. This geomechanical model will be tested during hydraulic stimulation of well 27-15 as part of the Desert Peak EGS Project, which is intended to enhance formation permeability through self-propping shear failure. If this stimulation is successful, then preferential activation of normal faults associated with the current stress state should generate a zone of enhanced permeability propagating to the SSW, in the direction of nearby geothermal injection and production wells, and to the NNE, into an unexploited portion of the field. These results indicate that well 27-15 is a viable candidate for EGS stimulation and complements research by other investigators, including cuttings and core testing, geochemical tracer studies, pressure transient analyses, and micro-seismic monitoring.

Hickman, S.; Davatzes, N. C.

2009-12-01

272

Measuring well hydraulic connectivity in fractured bedrock using periodic slug tests  

NASA Astrophysics Data System (ADS)

Periodic hydraulic experiments were conducted in a five-spot well cluster completed in a single bedding plane fracture. Tests were performed by using a winch-operated slug (submerged solid cylinder) to create a periodic head disturbance in one well and observing the phase shift and attenuation of the head response in the remaining wells. Transmissivity (T) and storativity (S) were inverted independently from head response. Inverted T decreased and S increased with oscillation period. Estimated S was more variable among well pairs than T, suggesting S may be a better estimator of hydraulic connectivity among closely spaced wells. These estimates highlighted a zone of poor hydraulic connection that was not identified by a constant rate test conducted in the same wells. Periodic slug tests appear to be a practical and effective technique for establishing local scale spatial variability in hydraulic parameters.

Guiltinan, Eric; Becker, Matthew W.

2015-02-01

273

METHOD DEVELOPMENT FOR DETERMINING THE HYDRAULIC CONDUCTIVITY OF FRACTURED POROUS MEDIA  

SciTech Connect

Plausible, but unvalidated, theoretical model constructs for unsaturated hydraulic conductivity of fractured porous media are currently used in Performance Assessment (PA) modeling for cracked saltstone and concrete (Flach 2011). The Nuclear Regulatory Commission (NRC) has expressed concern about the lack of model support for these assumed Moisture Characteristic Curves (MCC) data, as noted in Requests for Additional Information (RAIs) PA-8 and SP-4 (Savannah River Remediation, LLC, 2011). The objective of this task was to advance PA model support by developing an experimental method for determining the hydraulic conductivity of fractured cementitious materials under unsaturated conditions, and to demonstrate the technique on fractured saltstone samples. The task was requested through Task Technical Request (TTR) HLW-SSF-TTR-2012-0016 and conducted in accordance with Task Technical & Quality Assurance Plan (TTQAP) SRNL-TR-2012-00090. Preliminary method development previously conducted by Kohn et al. (2012) identified transient outflow extraction as the most promising method for characterizing the unsaturated properties of fractured porous media. While the research conducted by Kohn et al. (2012) focused on fractured media analogs such as stacked glass slides, the current task focused directly on fractured saltstone. For this task, four sample types with differing fracture geometries were considered: 1) intact saltstone, 2) intact saltstone with a single saw cut, smooth surface fracture, 3) micro-fractured saltstone (induced by oven drying), and 4) micro-fractured saltstone with a single, fully-penetrating, rough-surface fracture. Each sample type was tested initially for saturated hydraulic conductivity following method ASTM D 5084 using a flexible wall permeameter. Samples were subsequently tested using the transient outflow extraction method to determine cumulative outflow as a function of time and applied pressure. Of the four sample types tested, two yielded datasets suitable for analysis (sample types 3 and 4). The intact saltstone sample (sample type 1) did not yield any measureable outflow over the pressure range of the outflow test (0-1000 cm H{sub 2}O). This was expected because the estimated air entry pressure for intact saltstone is on the order of 100,000 cm H{sub 2}O (Dixon et al., 2009). The intact saltstone sample with a single saw cut smooth surface fracture (sample type 2) did not produce useable data because the fracture completely drained at less than 10 cm H{sub 2}O applied pressure. The cumulative outflow data from sample types 3 and 4 were analyzed using an inverse solution of the Richard’s equation for water flow in variably saturated porous media. This technique was implemented using the computer code Hydrus-1D (Šim?nek et al., 2008) and the resulting output included the van Genuchten-Mualem water retention and relative permeability parameters and predicted saturated hydraulic conductivity (Van Genuchten, 1980; Van Genuchten et al., 1991). Estimations of relative permeability and saturated conductivity are possible because the transient response of the sample to pressure changes is recorded during the multi-step outflow extraction test. Characteristic curves were developed for sample types 3 and 4 based on the results of the transient outflow method and compared to that of intact saltstone previously reported by Dixon et al. (2009). The overall results of this study indicate that the outflow extraction method is suitable for measuring the hydraulic properties of micro-fractured porous media. The resulting cumulative outflow data can be analyzed using the computer code Hydrus-1D to generate the van Genuchten curve fitting parameters that adequately describe fracture drainage. The resulting characteristic curves are consistent with blended characteristic curves that combine the behaviors of low pressure drainage associated with fracture flow with high pressure drainage from the bulk saltstone matrix.

Dixon, K.

2013-09-30

274

Investigation of the effects of fractured porous media on hydraulic tests—an experimental study at laboratory scale using single well methods  

NASA Astrophysics Data System (ADS)

In this paper, a study of detailed pneumatic tests at laboratory scale is presented. The study comprises two different test methods, which were conducted on an unsaturated fractured sandstone block of about 1 m 3 volume. First, a steady-state flow field with constant gas injection pressure and consequently constant gas flow rates was applied to the fractured sandstone block via a vertical borehole. The discharge of the injected gas was measured at the block surface. Second, a constant gas pressure was injected over the borehole and the transient pressure buildup was recorded at the block surface. It was the objective of the study to investigate the effects of the fractured porous system on pneumatic measurements and to provide an insight into processes occurring during flow and pressure buildup in fractured porous media. This is an essential prerequisite for a reliable validation of different modeling approaches, and it can further assist to improve techniques for the determination of the heterogeneity of hydraulic parameters in fractured porous media. The analysis of the distribution of the flow field and the temporal and spatial evolution of pressure buildup during the hydraulic tests shows that the direction and contribution of the flow field is highly depending on the spatial distribution and the characteristics of the fracture network as well as on the position of the observation points with respect to highly conductive structures. Finally, the introduced test methods are suitable tools for the characterization of the heterogeneous nature of fractured porous media and for the interpretation of the effects of the heterogeneous system on hydraulic tests.

Leven, C.; Sauter, M.; Teutsch, G.; Dietrich, P.

2004-09-01

275

Hydraulic Stimulation of Fracture Permeability in Volcanic and Metasedimentary Rocks at the Desert Peak Geothermal Field, Nevada  

NASA Astrophysics Data System (ADS)

An integrated study of fluid flow, fracturing, stress and rock mechanical properties is being conducted to develop the geomechanical framework for creating an Enhanced Geothermal System (EGS) through hydraulic stimulation. This stimulation is being carried out in the relatively impermeable well 27-15 located on the margins of the Desert Peak Geothermal Field, in silicified rhyolite tuffs and metamorphosed mudstones at depths of ~0.9 to 1.1 km and ambient temperatures of ~180 to 195° C. Extensive drilling-induced tensile fractures seen in image logs from well 27-15 indicate that the direction of the minimum horizontal principal stress, Shmin, is 114±17°. This orientation is consistent with normal faulting on ESE- and WNW-dipping normal faults also seen in these image logs. A hydraulic fracturing stress test conducted at 931 m indicates that the magnitude of Shmin is 13.8 MPa, which is ~0.61 of the calculated vertical stress, Sv. Coulomb failure calculations using these stresses and friction coefficients measured on core indicate that shear failure should be induced on pre-existing fractures once fluid pressures are increased ~2.5 MPa or more above the ambient formation fluid pressure. The resulting activation of faults well-oriented for shear failure should generate a zone of enhanced permeability propagating to the SSW, in the direction of nearby geothermal injection and production wells, and to the NNE, into an unexploited part of the field. Stimulation of well 27-15 began in August 2010, and is being monitored by flow-rate/pressure recording, a local seismic network, periodic temperature-pressure-flowmeter logging, tracer tests and pressure transient analyses. An initial phase of shear stimulation was carried out over 110 days at low pressures (< Shmin) and low injection rates (< 380 l/min), employing stepwise increases in pressure to induce shear failure along pre-existing natural fractures. This phase increased injectivity by one order of magnitude. Chelating agents and mud acid treatments were then used to dissolve mineral precipitates and open up partially sealed fractures. This chemical stimulation phase only temporarily increased injectivity and worsened the stability of the wellbore. A large-volume hydraulic fracturing operation was subsequently carried out at high pressures (> Shmin) and high injection rates (up to 2800 l/min) over 23 days to promote fluid pressure transfer to greater distances from the borehole, resulting in an additional 4-fold increase in injectivity. Locations of microseismic events induced by these operations plus tracer testing showed growth of the stimulated volume between well 27-15 and active geothermal wells located ~0.5 to 2 km to the SSW, as predicted by the stress model. Future plans for the Desert Peak EGS project involve augmenting the seismic array before executing additional hydraulic fracturing and shear stimulation to further improve the injection performance of well 27-15.

Hickman, S.; Davatzes, N. C.; Zemach, E.; Stacey, R.; Drakos, P. S.; Lutz, S.; Rose, P. E.; Majer, E.; Robertson-Tait, A.

2011-12-01

276

Evaluating the performance of hydraulically-fractured shale gas resources in the Appalachian Basin (Invited)  

NASA Astrophysics Data System (ADS)

Evaluating the performance of engineered-natural systems, such as hydraulically-fractured shales associated with natural gas recovery, depends on an understanding of fracture growth within and outside of the target shale formation, as well as the potential for gas and fluids to migrate to other subsurface resources or underground sources of drinking water. The NETL-Regional University Alliance (NETL-RUA) has a broad research portfolio connected with development of hydraulically-fractured shale resources in the Appalachian Basin. Through a combined field, experimental, modeling, and existing data evaluation effort, the following questions are being addressed: 1) Which subsurface features control the extent to which fractures migrate out of the target fracture zone? 2) Can we improve methods for analyzing natural geochemical tracers? What combination of natural and synthetic tracers can best be used to evaluate subsurface fluid and gas migration? 3) How is wellbore integrity affected by existing shallow gas? Can we predict how shallow groundwater hydrology changes due to drilling? 4) Where are existing wellbores and natural fractures located? What field methods can be used to identify the location of existing wells? To date the NETL-RUA team has focused on four key areas: fracture growth, natural isotopic tracers, impacts of well drilling on shallow hydrology, and statistics on wellbores (locations and conditions). We have found that fracture growth is sensitive to overburden geomechanical features, and that the maximum fracture height outside of the Marcellus Shale aligns with prior assessments (e.g., Fisher et al., 2012). The team has also developed methodologies for the rapid preparation of produced-water samples by MC-ICP-MS and ICP-MS; we are using these methodologies to investigate the potential of key geochemical indicators and species of interest (Sr, Ra) as indicators of fluid and gas migration in the Appalachian Basin. Experimental work on subsurface geochemical reactions in the presence of hydraulic fracturing fluid is underway to evaluate potential impacts on produced water chemistry and fracture stability within the shale formation. Additional laboratory experiments, coupled with modeling efforts, are evaluating the effects of well drilling on shallow groundwater hydrology, and the potential for shallow gas to affect cement hydration. At the field scale, the density and distribution of existing wellbores are being assessed through detection with remote magnetometer surveys, and compilation and analysis of existing wellbore databases. Results from these varied research efforts will be used in future predictive assessments of the behavior of engineered shale gas systems.

Hakala, A.; Wall, A. J.; Guthrie, G.

2013-12-01

277

Correlations to predict frictional pressure loss of hydraulic-fracturing slurry in coiled tubing  

SciTech Connect

Compared with conventional-tubing fracturing, coiled-tubing (CT) fracturing has several advantages. CT fracturing has become an effective stimulation technique for multizone oil and gas wells. It is also an attractive production-enhancement method for multiseam coalbed-methane wells, and wells with bypassed zones. The excessive frictional pressure loss through CT has been a concern in fracturing. The small diameter of the string limits the cross-sectional area open to flow. Furthermore, the tubing curvature causes secondary flow and results in extra flow resistance. This increased frictional pressure loss results in high surface pumping pressure. The maximum possible pump rate and sand concentration, therefore, have to be reduced. To design a CT fracturing job properly, it is essential to predict the frictional pressure loss through the tubing accurately. This paper presents correlations for the prediction of frictional pressure loss of fracturing slurries in straight tubing and CT. They are developed on the basis of full-scale slurry-flow tests with 11/2-in. CT and slurries prepared with 35 lbm/1,000 gal of guar gel. The extensive experiments were conducted at the full-scale CT-flow test facility. The proposed correlations have been verified with the experimental data and actual field CT-fracturing data. Case studies of wells recently fractured are provided to demonstrate the application of the correlations. The correlations will be useful to the CT engineers in their hydraulics design calculations.

Shah, S.; Zhoi, Y.X.; Bailey, M.; Hernandez, J. [University of Oklahoma, Norman, OK (United States)

2009-08-15

278

FINAL REPORT. CONTROL OF BIOLOGICALLY ACTIVE DEGRADATION ZONES BY VERTICAL HETEROGENEITY: APPLICATIONS IN FRACTURED MEDIA  

EPA Science Inventory

The key objective of this research was to determine the distribution of biologically active contaminant degradation zones in a fractured, subsurface medium with respect to vertical heterogeneities. Our expectation was that hydrogeological properties would determine the size, d...

279

Identification of subsurface fractures in the Austin Chalk using vertical seismic profiles  

E-print Network

IDENTIFICATION OF SUSSURFACE FRACTURES IN THE AUSTIN CHALK USING VERTICAL SEISMIC PROFILES A Thesis by KYLE THOMAS LEWALLEN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1992 Major Subject: Geophysics IDENTIFICATION OF SUBSURFACE FRACTURES IN THE AUSTIN CHALK USING VERTICAL SEISMIC PROFILES A Thesis by KYLE THOMAS LEWALLEN Approved as to style and content by: T. W. Spencer...

Lewallen, Kyle Thomas

2012-06-07

280

Characterization of fracture permeability with high-resolution vertical flow measurements during borehole pumping.  

USGS Publications Warehouse

The distribution of fracture permeability in granitic rocks was investigated by measuring the distribution of vertical flow in boreholes during periods of steady pumping. Pumping tests were conducted at two sites chosen to provide examples of moderately fractured rocks near Mirror Lake, New Hampshire and intensely fractured rocks near Oracle, Arizona. A sensitive heat-pulse flowmeter was used for accurate measurements of vertical flow as low as 0.2 liter per minute. Results indicate zones of fracture permeability in crystalline rocks are composed of irregular conduits that cannot be approximated by planar fractures of uniform aperture, and that the orientation of permeability zones may be unrelated to the orientation of individual fractures within those zones.-Authors

Paillet, F.L.; Hess, A.E.; Cheng, C.H.; Hardin, E.

1987-01-01

281

Discrete element modeling of rock deformation, fracture network development and permeability evolution under hydraulic stimulation  

SciTech Connect

Key challenges associated with the EGS reservoir development include the ability to reliably predict hydraulic fracturing and the deformation of natural fractures as well as estimating permeability evolution of the fracture network with time. We have developed a physics-based rock deformation and fracture propagation simulator by coupling a discrete element model (DEM) for fracturing with a network flow model. In DEM model, solid rock is represented by a network of discrete elements (often referred as particles) connected by various types of mechanical bonds such as springs, elastic beams or bonds that have more complex properties (such as stress-dependent elastic constants). Fracturing is represented explicitly as broken bonds (microcracks), which form and coalesce into macroscopic fractures when external and internal load is applied. The natural fractures are represented by a series of connected line segments. Mechanical bonds that intersect with such line segments are removed from the DEM model. A network flow model using conjugate lattice to the DEM network is developed and coupled with the DEM. The fluid pressure gradient exerts forces on individual elements of the DEM network, which therefore deforms the mechanical bonds and breaks them if the deformation reaches a prescribed threshold value. Such deformation/fracturing in turn changes the permeability of the flow network, which again changes the evolution of fluid pressure, intimately coupling the two processes. The intimate coupling between fracturing/deformation of fracture networks and fluid flow makes the meso-scale DEM- network flow simulations necessary in order to accurately evaluate the permeability evolution, as these methods have substantial advantages over conventional continuum mechanical models of elastic rock deformation. The challenges that must be overcome to simulate EGS reservoir stimulation, preliminary results, progress to date and near future research directions and opportunities will be discussed. Methodology for coupling the DEM model with continuum flow and heat transport models will also be discussed.

Shouchun Deng; Robert Podgorney; Hai Huang

2011-02-01

282

Microbial Community Changes in Hydraulic Fracturing Fluids and Produced Water from Shale Gas Extraction  

SciTech Connect

Microbial communities associated with produced water from hydraulic fracturing are not well understood, and their deleterious activity can lead to significant increases in production costs and adverse environmental impacts. In this study, we compared the microbial ecology in prefracturing fluids (fracturing source water and fracturing fluid) and produced water at multiple time points from a natural gas well in southwestern Pennsylvania using 16S rRNA gene-based clone libraries, pyrosequencing, and quantitative PCR. The majority of the bacterial community in prefracturing fluids constituted aerobic species affiliated with the class Alphaproteobacteria. However, their relative abundance decreased in produced water with an increase in halotolerant, anaerobic/facultative anaerobic species affiliated with the classes Clostridia, Bacilli, Gammaproteobacteria, Epsilonproteobacteria, Bacteroidia, and Fusobacteria. Produced water collected at the last time point (day 187) consisted almost entirely of sequences similar to Clostridia and showed a decrease in bacterial abundance by 3 orders of magnitude compared to the prefracturing fluids and produced water samplesfrom earlier time points. Geochemical analysis showed that produced water contained higher concentrations of salts and total radioactivity compared to prefracturing fluids. This study provides evidence of long-term subsurface selection of the microbial community introduced through hydraulic fracturing, which may include significant implications for disinfection as well as reuse of produced water in future fracturing operations.

Mohan, Arvind Murali; Hartsock, Angela; Bibby, Kyle J.; Hammack, Richard W.; Vidic, Radisav D.; Gregory, Kelvin B.

2013-11-19

283

Microbial community changes in hydraulic fracturing fluids and produced water from shale gas extraction.  

PubMed

Microbial communities associated with produced water from hydraulic fracturing are not well understood, and their deleterious activity can lead to significant increases in production costs and adverse environmental impacts. In this study, we compared the microbial ecology in prefracturing fluids (fracturing source water and fracturing fluid) and produced water at multiple time points from a natural gas well in southwestern Pennsylvania using 16S rRNA gene-based clone libraries, pyrosequencing, and quantitative PCR. The majority of the bacterial community in prefracturing fluids constituted aerobic species affiliated with the class Alphaproteobacteria. However, their relative abundance decreased in produced water with an increase in halotolerant, anaerobic/facultative anaerobic species affiliated with the classes Clostridia, Bacilli, Gammaproteobacteria, Epsilonproteobacteria, Bacteroidia, and Fusobacteria. Produced water collected at the last time point (day 187) consisted almost entirely of sequences similar to Clostridia and showed a decrease in bacterial abundance by 3 orders of magnitude compared to the prefracturing fluids and produced water samplesfrom earlier time points. Geochemical analysis showed that produced water contained higher concentrations of salts and total radioactivity compared to prefracturing fluids. This study provides evidence of long-term subsurface selection of the microbial community introduced through hydraulic fracturing, which may include significant implications for disinfection as well as reuse of produced water in future fracturing operations. PMID:24088205

Murali Mohan, Arvind; Hartsock, Angela; Bibby, Kyle J; Hammack, Richard W; Vidic, Radisav D; Gregory, Kelvin B

2013-11-19

284

Downhole microseismic monitoring of hydraulic fracturing: a full-waveform approach for complete moment tensor inversion and stress estimation  

E-print Network

Downhole microseismics has gained in popularity in recent years as a way to characterize hydraulic fracturing sources and to estimate in-situ stress state. Conventional approaches only utilize part of the information ...

Song, Fuxian

2010-01-01

285

Felt seismicity associated with shale gas hydraulic fracturing: The first documented example in Europe  

NASA Astrophysics Data System (ADS)

describe the origin of felt seismicity during the hydraulic fracturing of the Carboniferous Bowland Shale at the Preese Hall 1 exploration well near Blackpool in the UK during 2011. The seismicity resulted from the interaction of hydraulic fracturing and a fault, the location of which was unknown at the time but has subsequently been located and does not intersect the well borehole. Waveform cross correlation is used to detect 50 events in the sequence. A representative hypocenter and strike-slip focal mechanism is calculated using the best recorded seismic event. The hypocenter is calculated to lie 300-400 m east, and 330-360 m below the injection point and shown to lie on a fault imaged using 3-D seismic at a depth of about 2930 m. The 3-D survey shows that not only the event hypocenter but also the focal mechanism correlates strongly with a subsequently identifiable transpressional fault formed during the Late Carboniferous (Variscan) basin inversion.

Clarke, Huw; Eisner, Leo; Styles, Peter; Turner, Peter

2014-12-01

286

Paving the road for hydraulic fracturing in Paleozoic tight gas reservoirs in Abu Dhabi  

NASA Astrophysics Data System (ADS)

This study contributes to the ongoing efforts of Abu Dhabi National Oil Company (ADNOC) to improve gas production and supply in view of increasing demand and diminishing conventional gas reservoirs in the region. The conditions of most gas reservoirs with potentially economical volumes of gas in Abu Dhabi are tight abrasive deep sand reservoirs at high temperature and pressures. Thus it inevitably tests the limit of both conventional thinking and technology. Accurate prediction of well performance is a major challenge that arises during planning phase. The primary aim is to determine technical feasibility for the implementation of the hydraulic fracture technology in a new area. The ultimate goal is to make economical production curves possible and pave the road to tap new resource of clean hydrocarbon energy source. The formation targeted in this study is characterized by quartzitic sandstone layers and variably colored shale and siltstones with thin layers of anhydrites. It dates back from late Permian to Carboniferous age. It forms rocks at the lower reservoir permeability ranging from 0.2 to less than 1 millidarcy (mD). When fractured, the expected well flow in Abu Dhabi offshore deep gas wells will be close to similar tight gas reservoir in the region. In other words, gas production can be described as transient initially with high rates and rapidly declining towards a pseudo-steady sustainable flow. The study results estimated fracturing gradient range from 0.85 psi/ft to 0.91 psi/ft. In other words, the technology can be implemented successfully to the expected rating without highly weighted brine. Hence, it would be a remarkable step to conduct the first hydraulic fracturing successfully in Abu Dhabi which can pave the road to tapping on a clean energy resource. The models predicted a remarkable conductivity enhancement and an increase of production between 3 to 4 times after fracturing. Moreover, a sustainable rate above 25 MMSCFD between 6 to 10 years is predicted based on a single well model. The forecasts also show that most of the contribution will come from one zone and therefore optimized operational cost can be achieved in future. Once pressures during a diagnostic injection test are known prior to the main hydraulic fracturing treatment, precise calibration will enable accurate design of fracture geometry and containment for full field development. The feasibility of hydraulic fracture is based on available offset well data. The biggest two challenges in Abu-Dhabi at this stage are high depths and high temperatures as well as offshore conditions. For this reason, a higher well pressure envelop and fracturing string installation is envisaged as a necessity in a future well where unknown tectonic stress could result in higher fracturing load. Finally the study recommends drilling a candidate well designed for the implementation of hydraulic fracturing. This well should consider required pressure rating for the fracturing string. Thermal design considerations will also play a role during production due to high temperature. A dipole or multi pole sonic log from the same well is essential to confirm in situ stresses. The planned well will be in the crest at close proximity to studied offset wells to minimize uncertainty where tested wells produced dry gas and to avoid drilling to watered zones down the flank of the reservoir.

Alzarouni, Asim

287

Three-dimensional seismic characterization of a venting site reveals compelling indications of natural hydraulic fracturing  

Microsoft Academic Search

Based on a three-dimensional high-resolution seismic survey off Vancouver Island, Canada, we show that natural hydraulic fracturing is an efficient process to create permeable pathways for focused fluid upflow at submarine venting sites. The pockmark structure examined in this study is located on top of an accreted ridge, where the low-permeability base of the gas hydrate stability field is also

L. Zühlsdorff; V. Spieß

2004-01-01

288

Hydraulic fracturing and overcoring stress measurements in a deep borehole at the Stripa Test Mine, Sweden  

SciTech Connect

Recently, a workable method was developed for performing overcoring measurements in holes hundreds of meters in length. With the need to obtain in situ stress values for nuclear waste disposal simulation experiments at the Stripa Mine in central Sweden, the task of running both the Power Board's Leeman triaxial cell and hydraulic fracturing in the same hole was undertaken. This paper is a report of the results of the comparative measurements. 9 figures, 1 table.

Doe, T.; Ingevald, K.; Strindell, L.; Haimson, B.; Carlsson, H.

1981-03-01

289

Determination of formation permeability using back-pressure test data from hydraulically-fractured, low-permeability gas wells  

E-print Network

DETERMINATION OF FORMATION PERMEABILITY USING BACX-PRESSURE TEST DATA FROM HYDRAULICALLY-FRACTURED, LOW-PERMEABILITY GAS WELLS A Thesis JOHN PAUL KRAWTZ Submitted to the Graduate College of Texas AsJ4 University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1984 Major subject: petroleum Engineering DETERMINATION OF FORMATION PERMEABILITY USING BACK-PRESSURE TEST DATA FROM HYDRAULICALLY-FRACTURED, LOW-PERMEABILITY GAS WELLS A Thesis JOHN PAUL KRAWTZ...

Krawtz, John Paul

1984-01-01

290

Investigation of post hydraulic fracturing well cleanup physics in the Cana Woodford Shale  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing was first carried out in the 1940s and has gained popularity in current development of unconventional resources. Flowing back the fracturing fluids is critical to a frac job, and determining well cleanup characteristics using the flowback data can help improve frac design. It has become increasingly important as a result of the unique flowback profiles observed in some shale gas plays due to the unconventional formation characteristics. Computer simulation is an efficient and effective way to tackle the problem. History matching can help reveal some mechanisms existent in the cleanup process. The Fracturing, Acidizing, Stimulation Technology (FAST) Consortium at Colorado School of Mines previously developed a numerical model for investigating the hydraulic fracturing process, cleanup, and relevant physics. It is a three-dimensional, gas-water, coupled fracture propagation-fluid flow simulator, which has the capability to handle commonly present damage mechanisms. The overall goal of this research effort is to validate the model on real data and to investigate the dominant physics in well cleanup for the Cana Field, which produces from the Woodford Shale in Oklahoma. To achieve this goal, first the early time delayed gas production was explained and modeled, and a simulation framework was established that included all three relevant damage mechanisms for a slickwater fractured well. Next, a series of sensitivity analysis of well cleanup to major reservoir, fracture, and operational variables was conducted; five of the Cana wells' initial flowback data were history matched, specifically the first thirty days' gas and water producing rates. Reservoir matrix permeability, net pressure, Young's modulus, and formation pressure gradient were found to have an impact on the gas producing curve's shape, in different ways. Some moderately good matches were achieved, with the outcome of some unknown reservoir information being proposed using the corresponding inputs from the history matching study. It was also concluded that extended shut-in durations after fracturing all the stages do not delay production in the overall situation. The success of history matching will further knowledge of well cleanup characteristics in the Cana Field, enable the future usage of this tool in other hydraulically fractured gas wells, and help operators optimize the flowback operations. Future improvements can be achieved by further developing the current simulator so that it has the capability of optimizing its grids setting every time the user changes the inputs, which will result in better stability when the relative permeability setting is modified.

Lu, Rong

291

Coupled Finite Volume and Discrete-Finite element Methods for Modeling Hydraulic Fracturing in Geologic Formations  

NASA Astrophysics Data System (ADS)

ABSTRACT: High demand for stimulation treatments of fluid-state hydrocarbon reservoirs is driving increased interest in improved understanding of the fundamentals of hydraulic fracturing of geologic formations. In addition, prediction of caprock integrity under the load of geologically sequestered, pressurized CO2 requires better understanding fluid-rock interactions. The approach described here addresses modeling of hydraulic fracturing at the meso-scale, using a discrete-finite element method code (LDEC) coupled to a modified finite volume method to capture compressible flow in a propagating fracture. Leak-off is also addressed through a model parameterized by flow rate and cumulative flow through the fracture face; this approach is used to better approximate the functional form of the dominant underlying chemo-physical phenomena which lead to permeability loss at the fracture face over typical models, which are often parameterized only by time and calibrated, through a set of parameters, to match experimental data. A simulation of a standard fracture injection test is used to compare the results of the proposed leak-off model with the popular Carter leak-off model and shows excellent agreement between the two models. Also, the finite volume approach is verified against analytical solutions for constant aperture parallel plate flow, and results of a validation study comparing simulation results with an experiment on the propagation of a fracture in a brittle, homogeneous polymer are discussed. ACKNOWLEDGEMENTS: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Johnson, S.; Morris, J.

2008-12-01

292

Analysis of hydraulic fracturing flowback and produced waters using accurate mass: identification of ethoxylated surfactants.  

PubMed

Two series of ethylene oxide (EO) surfactants, polyethylene glycols (PEGs from EO3 to EO33) and linear alkyl ethoxylates (LAEs C-9 to C-15 with EO3-EO28), were identified in hydraulic fracturing flowback and produced water using a new application of the Kendrick mass defect and liquid chromatography/quadrupole-time-of-flight mass spectrometry. The Kendrick mass defect differentiates the proton, ammonium, and sodium adducts in both singly and doubly charged forms. A structural model of adduct formation is presented, and binding constants are calculated, which is based on a spherical cagelike conformation, where the central cation (NH4(+) or Na(+)) is coordinated with ether oxygens. A major purpose of the study was the identification of the ethylene oxide (EO) surfactants and the construction of a database with accurate masses and retention times in order to unravel the mass spectral complexity of surfactant mixtures used in hydraulic fracturing fluids. For example, over 500 accurate mass assignments are made in a few seconds of computer time, which then is used as a fingerprint chromatogram of the water samples. This technique is applied to a series of flowback and produced water samples to illustrate the usefulness of ethoxylate "fingerprinting", in a first application to monitor water quality that results from fluids used in hydraulic fracturing. PMID:25164376

Thurman, E Michael; Ferrer, Imma; Blotevogel, Jens; Borch, Thomas

2014-10-01

293

Biocides in hydraulic fracturing fluids: a critical review of their usage, mobility, degradation, and toxicity.  

PubMed

Biocides are critical components of hydraulic fracturing ("fracking") fluids used for unconventional shale gas development. Bacteria may cause bioclogging and inhibit gas extraction, produce toxic hydrogen sulfide, and induce corrosion leading to downhole equipment failure. The use of biocides such as glutaraldehyde and quaternary ammonium compounds has spurred a public concern and debate among regulators regarding the impact of inadvertent releases into the environment on ecosystem and human health. This work provides a critical review of the potential fate and toxicity of biocides used in hydraulic fracturing operations. We identified the following physicochemical and toxicological aspects as well as knowledge gaps that should be considered when selecting biocides: (1) uncharged species will dominate in the aqueous phase and be subject to degradation and transport whereas charged species will sorb to soils and be less bioavailable; (2) many biocides are short-lived or degradable through abiotic and biotic processes, but some may transform into more toxic or persistent compounds; (3) understanding of biocides' fate under downhole conditions (high pressure, temperature, and salt and organic matter concentrations) is limited; (4) several biocidal alternatives exist, but high cost, high energy demands, and/or formation of disinfection byproducts limits their use. This review may serve as a guide for environmental risk assessment and identification of microbial control strategies to help develop a sustainable path for managing hydraulic fracturing fluids. PMID:25427278

Kahrilas, Genevieve A; Blotevogel, Jens; Stewart, Philip S; Borch, Thomas

2015-01-01

294

Iodide, bromide, and ammonium in hydraulic fracturing and oil and gas wastewaters: environmental implications.  

PubMed

The expansion of unconventional shale gas and hydraulic fracturing has increased the volume of the oil and gas wastewater (OGW) generated in the U.S. Here we demonstrate that OGW from Marcellus and Fayetteville hydraulic fracturing flowback fluids and Appalachian conventional produced waters is characterized by high chloride, bromide, iodide (up to 56 mg/L), and ammonium (up to 420 mg/L). Br/Cl ratios were consistent for all Appalachian brines, which reflect an origin from a common parent brine, while the I/Cl and NH4/Cl ratios varied among brines from different geological formations, reflecting geogenic processes. There were no differences in halides and ammonium concentrations between OGW originating from hydraulic fracturing and conventional oil and gas operations. Analysis of discharged effluents from three brine treatment sites in Pennsylvania and a spill site in West Virginia show elevated levels of halides (iodide up to 28 mg/L) and ammonium (12 to 106 mg/L) that mimic the composition of OGW and mix conservatively in downstream surface waters. Bromide, iodide, and ammonium in surface waters can impact stream ecosystems and promote the formation of toxic brominated-, iodinated-, and nitrogen disinfection byproducts during chlorination at downstream drinking water treatment plants. Our findings indicate that discharge and accidental spills of OGW to waterways pose risks to both human health and the environment. PMID:25587644

Harkness, Jennifer S; Dwyer, Gary S; Warner, Nathaniel R; Parker, Kimberly M; Mitch, William A; Vengosh, Avner

2015-02-01

295

New tracers identify hydraulic fracturing fluids and accidental releases from oil and gas operations.  

PubMed

Identifying the geochemical fingerprints of fluids that return to the surface after high volume hydraulic fracturing of unconventional oil and gas reservoirs has important applications for assessing hydrocarbon resource recovery, environmental impacts, and wastewater treatment and disposal. Here, we report for the first time, novel diagnostic elemental and isotopic signatures (B/Cl, Li/Cl, ?11B, and ?7Li) useful for characterizing hydraulic fracturing flowback fluids (HFFF) and distinguishing sources of HFFF in the environment. Data from 39 HFFFs and produced water samples show that B/Cl (>0.001), Li/Cl (>0.002), ?11B (25-31‰) and ?7Li (6-10‰) compositions of HFFF from the Marcellus and Fayetteville black shale formations were distinct in most cases from produced waters sampled from conventional oil and gas wells. We posit that boron isotope geochemistry can be used to quantify small fractions (?0.1%) of HFFF in contaminated fresh water and likely be applied universally to trace HFFF in other basins. The novel environmental application of this diagnostic isotopic tool is validated by examining the composition of effluent discharge from an oil and gas brine treatment facility in Pennsylvania and an accidental spill site in West Virginia. We hypothesize that the boron and lithium are mobilized from exchangeable sites on clay minerals in the shale formations during the hydraulic fracturing process, resulting in the relative enrichment of boron and lithium in HFFF. PMID:25327769

Warner, N R; Darrah, T H; Jackson, R B; Millot, R; Kloppmann, W; Vengosh, A

2014-11-01

296

'Fracking' Controversy and Communication: Using National Survey Data to Understand Public Perceptions of Hydraulic Fracturing (Invited)  

NASA Astrophysics Data System (ADS)

The recent push to develop unconventional sources of oil and gas both in the U.S. and abroad via hydraulic fracturing ('fracking') has generated a great deal of controversy. Effectively engaging stakeholders and setting appropriate policies requires insights into current public perceptions of this issue. Using a nationally representative U.S. sample (N=1,061), we examine public perceptions of hydraulic fracturing including: 'top of mind' associations; familiarity with the issue; levels of support/opposition; and predictors of such judgments. Similar to findings on other emerging technologies, our results suggest limited familiarity with the process and its potential impacts and considerable uncertainty about whether to support it. Multiple regression analysis (r2 = 0.49) finds that women, those holding egalitarian worldviews, those who read newspapers more than once a week, those more familiar with hydraulic fracturing, and those who associate the process with environmental impacts are more likely to oppose fracking. In contrast, people more likely to support fracking tend to be older, hold a bachelor's degree or higher, politically conservative, watch TV news more than once a week, and associate the process with positive economic or energy supply outcomes. Based on these findings, we discuss recommendations for future research, risk communication, and energy policy.

Boudet, H. S.

2013-12-01

297

Characteristics of microseismic events induced during hydraulic fracturing experiments at the Hijiori hot dry rock geothermal energy site, Yamagata, Japan  

Microsoft Academic Search

Microseismicity accompanying hydraulic injection experiments at the Hijiori hot dry rock site was monitored by a network of ten borehole seismic stations deployed at an average distance of 2 km from the injection well. While expanding hydraulic fractures are almost aseismic, they can induce microseismic events. These events are probably caused by shear failures induced by high pore fluid pressures

Shunji Sasaki

1998-01-01

298

The Determination of Tectonic Stresses through Analysis of Hydraulic Well Fracturing  

Microsoft Academic Search

The well-fracturing operation is modeled by a band of uniform pressure and two bands of uniform shear stress acting in a cylindrical cavity in an infinite body. Two interesting regions of induced stress are: either end of the pressurized interval where the tan- gential stress is zero (the vertical stress is approximately 95 per cent of the pressure) and the

Ralph O. Kehle

1964-01-01

299

A Semi-Analytic Solution for Flow in Finite-Conductivity Vertical Fractures Using Fractal Theory  

E-print Network

analytic models are needed to accurately describe fluid flow in a hydraulic fracture and the problem has been approached from different directions in the past 3 decades - starting with the use of line-source functions for the infinite conductivity case...

Cossio Santizo, Manuel

2012-10-19

300

Investigation of blast-induced fracture in rock mass using reversed vertical seismic profiling  

NASA Astrophysics Data System (ADS)

The rock mass on quarry and pit wall surfaces is usually fractured during production blasting. Quantitative investigations of the fractured zones are needed for stabilization of the rock walls. In this study, the principle of reversed vertical seismic profiling (RVSP) was applied. A set of seismic geophones were arranged on the horizontal bench surface and seismic signals were generated along the vertical rock wall using a free-swinging hammer. The travel times of seismic rays were recorded and the P-wave velocities of the rock mass were analyzed using the Simultaneous Iterative Reconstruction Technique (SIRT). A series of site tests have been carried out on the rock walls at a granite quarry that are characterized by fractures. The fracture depth at various locations on the wall surface is thereby determined. The results indicate that RVSP provides an easy and reliable method to quantitatively evaluate the blasting-induced fractures in the rock mass.

Zou, D. H.; Wu, Y. K.

2001-10-01

301

Treatment of a Vertical Root Fracture Using Dual-Curing Resin Cement: A Case Report  

PubMed Central

Introduction. Vertical root fracture (VRF) is one of the most frustrating complications of root canal treatment. The prognosis of the root with VRF is poor therefore tooth extraction and root amputation are usually the only treatment options. However, bonding of the fracture line with adhesive resin cement during the intentional replantation procedure was recently suggested as an alternative to tooth extraction. Methods. A vertically fractured left maxillary incisor was carefully extracted, fracture line was treated with adhesive resin cement, a retrograde cavity was produced and filled with calcium-enriched mixture (CEM) cement, and tooth was replanted. Results. After 12 months the tooth was asymptomatic. The size of periapical radiolucency was noticeably reduced and there was no clinical sign of ankylosis. Conclusion. Using adhesive resin cement to bond the fracture lines extraorally in roots with VRF and intentional replantation of the reconstructed teeth could be considered as an alternative to tooth extraction, especially for anterior teeth. PMID:23316397

Moradi Majd, Nima; Akhtari, Farshid; Araghi, Solmaz; Homayouni, Hamed

2012-01-01

302

Repair of incomplete vertical root fractures in endodontically treated teeth--in vivo trials.  

PubMed

An in vivo clinical study was performed to evaluate the healing of a new approach to the repair of incomplete vertical root fractures. The two-stage surgical procedure incorporated ultrasonic fracture cleaning, bonding of the fracture repair with silver glass-ionomer cement, placement of a bone graft material, and application of guided-tissue regeneration. Of the six roots in the study, five failed within 2 to 11 months. One root continued to be symptom-free, without periodontal pocket formation for 1 yr, but then failed because of extension of the incomplete root fracture to the lingual of the root. PMID:8941753

Selden, H S

1996-08-01

303

INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS  

SciTech Connect

This report describes the work performed during the third year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling fluid flow through rough fractures and investigating the grid orientation effect in rectangular grid blocks particularly at high mobility ratio as our precursor to use a compositional simulator. We are developing a robust simulator using Voronoi grids to accurately represent natural and induced fractures. We are also verifying the accuracy of the simulation using scaled laboratory experiments to provide a benchmark for our simulation technique. No such simulator currently exists so this capability will represent a major breakthrough in simulation of gas injection in fractured systems. The following sections outline the results that appear in this report.

David S. Schechter

2004-10-10

304

Seismic detection of a hydraulic fracture from shear-wave VSP data at Lost Hills Field, California  

Microsoft Academic Search

The authors describe the results of a geophysical experiment in which shear waves (S-waves) were used to detect the presence of a hydraulic fracture in a diatomite reservoir at the Lost Hills Field. They show evidence that transient S-waves recorded in a monitor well represent diffracted energy that disappears as the fracture closes. They also show how, using simple models,

Mark A. Meadows; D. F. Winterstein

1994-01-01

305

Interpretation of seismic data from hydraulic fracturing experiments at the Fenton Hill, New Mexico, hot dry rock geothermal site  

Microsoft Academic Search

An attempt was made to synthesize the results of active seismic experiments carried out by the Los Alamos National Laboratory's Hot Dry Rock Project staff for determining the geometrical and physical properties of the fracture system produced by hydraulic fracturing in a hot, low-permeability rock. Interpretation of data from several reflection, transmission, and attenuation experiments using seismic probes in the

Keiiti Aki; Michael Fehler; R. L. Aamodt; J. N. Albright; R. M. Potter; C. M. Pearson; J. W. Tester

1982-01-01

306

Fractured gas well analysis: evaluation of in situ reservoir properties of low permeability gas wells stimulated by finite conductivity hydraulic fractures  

E-print Network

gas well. The Wellbore Fracture DEY (I) DEX (J) FIG. 1 - GRID PATTERN FOR SINULATION OF A VERTICALLY FRACTURED NELL fracture is placed in the I = 1 row of the grid pattern. When running the model with this plan view grid pattern, the well... made in this study, DEX (1) was set equal to . 001 feet. DEY (1) is always set equal to one-half the fracture width. Exception cards were used to read in high permeability and porosity in the cells containing the fracture. The dimensionless fracture...

Makoju, Charles Adoiza

2012-06-07

307

Hydraulics.  

ERIC Educational Resources Information Center

This curriculum guide contains a course in hydraulics to train entry-level workers for automotive mechanics and other fields that utilize hydraulics. The module contains 14 instructional units that cover the following topics: (1) introduction to hydraulics; (2) fundamentals of hydraulics; (3) reservoirs; (4) lines, fittings, and couplers; (5)…

Decker, Robert L.; Kirby, Klane

308

Using borehole geophysics and cross-borehole flow testing to define hydraulic connections between fracture zones in bedrock aquifers  

USGS Publications Warehouse

Nearly a decade of intensive geophysical logging at fractured rock hydrology research sites indicates that geophysical logs can be used to identify and characterize fractures intersecting boreholes. However, borehole-to-borehole flow tests indicate that only a few of the apparently open fractures found to intersect boreholes conduct flow under test conditions. This paper presents a systematic approach to fracture characterization designed to define the distribution of fractures along boreholes, relate the measured fracture distribution to structure and lithology of the rock mass, and define the nature of fracture flow paths across borehole arrays. Conventional electrical resistivity, gamma, and caliper logs are used to define lithology and large-scale structure. Borehole wall image logs obtained with the borehole televiewer are used to give the depth, orientation, and relative size of fractures in situ. High-resolution flowmeter measurements are used to identify fractures conducting flow in the rock mass adjacent to the boreholes. Changes in the flow field over time are used to characterize the hydraulic properties of fracture intersections between boreholes. Application of this approach to an array of 13 boreholes at the Mirror Lake, New Hamsphire site demonstrates that the transient flow analysis can be used to distinguish between fractures communicating with each other between observation boreholes, and those that are hydraulically isolated from each other in the surrounding rock mass. The Mirror Lake results also demonstrate that the method is sensitive to the effects of boreholes on the hydraulic properties of the fractured-rock aquifer. Experiments conducted before and after the drilling of additional boreholes in the array and before and after installation of packers in existing boreholes demonstrate that the presence of new boreholes or the inflation of packers in existing boreholes has a large effect on the measured hydraulic properties of the rock mass surrounding the borehole array. ?? 1993.

Paillet, F.L.

1993-01-01

309

Implementation of the Ensemble Kalman Filter in the Characterization of Hydraulic Fractures in Shale Gas Reservoirs by Integrating Downhole Temperature Sensing Technology  

E-print Network

Multi-stage hydraulic fracturing in horizontal wells has demonstrated successful results for developing unconventional low-permeability oil and gas reservoirs. Despite being vastly implemented by different operators across North America, hydraulic...

Moreno, Jose A

2014-08-12

310

Hydraulic characterization and optimization of total nitrogen removal in an aerated vertical subsurface flow treatment wetland.  

PubMed

In this study, a side-by-side comparison of two pilot-scale vertical subsurface flow constructed wetlands (6.2 m(2)×0.85 m, q(i)=95 L/m(2) d, ?(n)=3.5 d) handling primary treated domestic sewage was conducted. One system (VA-i) was set to intermittent aeration while the other was aerated continuously (VAp-c). Intermittent aeration was provided to VA-i in an 8 h on/4 h off pattern. The intermittently aerated wetland, VA-i, was observed to have 70% less nitrate nitrogen mass outflow than the continuously aerated wetland, VAp-c. Intermittent aeration was shown to increase treatment performance for TN while saving 33% of running energy cost for aeration. Parallel tracer experiments in the two wetlands showed hydraulic characteristics similar to one Continuously Stirred Tank Reactor (CSTR). Intermittent aeration did not significantly affect the hydraulic functioning of the system. Hydraulic efficiencies were 78% for VAp-c and 76% for VA-i. PMID:24747396

Boog, Johannes; Nivala, Jaime; Aubron, Thomas; Wallace, Scott; van Afferden, Manfred; Müller, Roland Arno

2014-06-01

311

The effect of different posts on fracture strength of roots with vertical fracture and re-attached fragments.  

PubMed

The aim of this in vitro study was to test the effect of different post systems on fracture strength of roots with re-attached fragments. Root canals of eighty extracted single-rooted human teeth were instrumented (ProFile) and randomly divided into two groups. The roots in the first group were vertically cracked, and the fragments were re-attached using Super Bond C&B (Sun Medical, Tokya, Japan). The roots in the second group were kept sound. Obturation of the roots was performed with MetaSEAL (Sun Medical) and gutta-percha. Post spaces were prepared, and the roots were restored with one of the followings: UniCore (Ultradent), Everstick (Stick Tech), Ribbond (Ribbond), ParaPost (Coltene/Whaledent) (n = 10). Four mm high build-ups were created (Clearfil DC Bond Core; Kuraray, Tokyo, Japan). Compressive loading of the samples was performed after 24 h (1 mm min(-1)). Mean load necessary to fracture each sample was recorded (Newton) and statistically analysed (One-way anova, t-tests). ParaPost showed the highest fracture strength among the roots with re-attached fragments (P < 0.05). UniCore and ParaPost systems showed similar fracture strength in the sound roots (P > 0.05). Re-attached fragments significantly reduced the fracture strength of roots in UniCore group (P = 0.000). Ribbond post showed mostly repairable fractures. Metal post (ParaPost) showed the highest fracture strength in the roots with re-attached fragments; however, fracture pattern was 41% non-repairable. Re-attached fragments significantly reduced the fracture strength of the roots in UniCore group. Prefabricated posts showed similar fracture strength in the sound roots. Customized post systems EverStick and Ribbond showed mostly repairable failure after loading in sound roots or roots with re-attached fragments. PMID:20406354

Ozcopur, B; Akman, S; Eskitascioglu, G; Belli, S

2010-08-01

312

Hydraulic Fracturing In Situ Stress Estimations in a Potential Geothermal Site, Seokmo Island, South Korea  

NASA Astrophysics Data System (ADS)

We conducted hydraulic fracturing (HF) in situ stress measurements in Seokmo Island, South Korea, to understand the stress state necessary to characterize a potential geothermal reservoir. The minimum horizontal principal stress was determined from shut-in pressures. In order to calculate the maximum horizontal principal stress ( S Hmax) using the classical Hubbert-Willis equation, we carried out hollow cylinder tensile strength tests and Brazilian tests in recovered cores at depths of HF tests. Both tests show a strong pressure rate dependency in tensile strengths, from which we derived a general empirical equation that can be used to convert laboratory determined tensile strength to that suitable for in situ. The determined stress regime (reverse-faulting) and S Hmax direction (ENE-WSW) at depths below ~300 m agrees with the first order tectonic stress. However the stress direction above ~300 m (NE-SW) appears to be interfered by topography effect due to a nearby ridge. The state of stress in Seokmo Island is in frictional equilibrium constrained by optimally oriented natural fractures and faults. However, a severe fluctuation in determined S Hmax values suggests that natural fractures with different frictional coefficients seem to control stress condition quite locally, such that S Hmax is relatively low at depths where natural fractures with low frictional coefficients are abundant, while S Hmax is relatively high at depths where natural fractures with low frictional coefficients are scarce.

Chang, Chandong; Jo, Yeonguk; Oh, Yangkyun; Lee, Tae Jong; Kim, Kwang-Yeom

2014-09-01

313

Hydraulic Anisotropy Characterization Using Azimuthal Self Potential Gradient [ASPG]: Results from Pneumatic Fracturing of Tight Clay Soils  

NASA Astrophysics Data System (ADS)

Recent studies have shown that bulk hydraulic anisotropy associated with fractures in fractured rock aquifers can be inferred from Azimuthal Self Potential Gradient (ASPG) measurements. This extremely simple technique involves measuring the self potential gradient as a function of azimuth with a pair of non polarizing electrodes connected to a voltmeter. The electrokinetic effect associated with the flow of fluids within fractures is the source of the ASPG signal. Fracture strike mapping at multiple sites has repeatedly demonstrated the effectiveness of the method at the field scale and indicated that the direction of flow can be determined from the polarity of relatively large ASPG signals. A laboratory study was conducted to determine whether ASPG could also be used to characterize the hydraulic anisotropy associated with the enhancement of permeability and porosity of tight unconsolidated soils (e.g. clays) as a result of pneumatic fracturing, a technique to improve the effectiveness of remediation efforts. Compressed kaolinite sediments were pneumatically fractured following industry procedures. The resulting fracture geometry was quantified from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. ASPG measurements were then made during injection of a simulated remedial treatment (electrolyte/dye) under an applied gas pressure. Consistent with previous findings in fractured rock aquifers, ASPG lobes are well correlated with azimuths of high fracture strike density suggesting that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. The magnitude of the ASPG signal scales linearly (linear correlation coefficients > 0.74) with the applied gas pressure gradient for any particular hydraulically-active fracture set and the positive lobe of the ASP anomaly denotes the flow direction within that fracture set. These findings demonstrate that applications of the simple ASPG technique go beyond characterization of hydraulic anisotropy in fractured bedrock aquifers. As demonstrated here, the method can characterize hydraulic anisotropy artificially created in tight unconsolidated soils and could be used to monitor the progress of remedial treatments applied to contaminated environments.

Slater, L.; Wishart, D.; Schnell, D.; Hermann, G.

2008-12-01

314

The role of toxicological science in meeting the challenges and opportunities of hydraulic fracturing.  

PubMed

We briefly describe how toxicology can inform the discussion and debate of the merits of hydraulic fracturing by providing information on the potential toxicity of the chemical and physical agents associated with this process, individually and in combination. We consider upstream activities related to bringing chemical and physical agents to the site, on-site activities including drilling of wells and containment of agents injected into or produced from the well, and downstream activities including the flow/removal of hydrocarbon products and of produced water from the site. A broad variety of chemical and physical agents are involved. As the industry expands this has raised concern about the potential for toxicological effects on ecosystems, workers, and the general public. Response to these concerns requires a concerted and collaborative toxicological assessment. This assessment should take into account the different geology in areas newly subjected to hydraulic fracturing as well as evolving industrial practices that can alter the chemical and physical agents of toxicological interest. The potential for ecosystem or human exposure to mixtures of these agents presents a particular toxicological and public health challenge. These data are essential for developing a reliable assessment of the potential risks to the environment and to human health of the rapidly increasing use of hydraulic fracturing and deep underground horizontal drilling techniques for tightly bound shale gas and other fossil fuels. Input from toxicologists will be most effective when employed early in the process, before there are unwanted consequences to the environment and human health, or economic losses due to the need to abandon or rework costly initiatives. PMID:24706166

Goldstein, Bernard D; Brooks, Bryan W; Cohen, Steven D; Gates, Alexander E; Honeycutt, Michael E; Morris, John B; Orme-Zavaleta, Jennifer; Penning, Trevor M; Snawder, John

2014-06-01

315

Estimating Hydraulic Conductivities in a Fractured Shale Formation from Pressure Pulse Testing and 3d Modeling  

NASA Astrophysics Data System (ADS)

In the framework of its research on the deep disposal of radioactive waste in shale formations, the French Institute for Radiological Protection and Nuclear Safety (IRSN) has developed a large array of in situ programs concerning the confining properties of shales in their underground research laboratory at Tournemire (SW France). One of its aims is to evaluate the occurrence and processes controlling radionuclide migration through the host rock, from the disposal system to the biosphere. Past research programs carried out at Tournemire covered mechanical, hydro-mechanical and physico-chemical properties of the Tournemire shale as well as water chemistry and long-term behaviour of the host rock. Studies show that fluid circulations in the undisturbed matrix are very slow (hydraulic conductivity of 10-14 to 10-15 m.s-1). However, recent work related to the occurrence of small scale fractures and clay-rich fault gouges indicate that fluid circulations may have been significantly modified in the vicinity of such features. To assess the transport properties associated with such faults, IRSN designed a series of in situ and laboratory experiments to evaluate the contribution of both diffusive and advective process on water and solute flux through a clay-rich fault zone (fault core and damaged zone) and in an undisturbed shale formation. As part of these studies, Modular Mini-Packer System (MMPS) hydraulic testing was conducted in multiple boreholes to characterize hydraulic conductivities within the formation. Pressure data collected during the hydraulic tests were analyzed using the nSIGHTS (n-dimensional Statistical Inverse Graphical Hydraulic Test Simulator) code to estimate hydraulic conductivity and formation pressures of the tested intervals. Preliminary results indicate hydraulic conductivities of 5.10-12 m.s-1 in the fault core and damaged zone and 10-14 m.s-1 in the adjacent undisturbed shale. Furthermore, when compared with neutron porosity data from borehole logging, porosity varies by a factor of 2.5 whilst hydraulic conductivity varies by 2 to 3 orders of magnitude. In addition, a 3D numerical reconstruction of the internal structure of the fault zone inferred from borehole imagery has been built to estimate the permeability tensor variations. First results indicate that hydraulic conductivity values calculated for this structure are 2 to 3 orders of magnitude above those measured in situ. Such high values are due to the imaging method that only takes in to account open fractures of simple geometry (sine waves). Even though improvements are needed to handle more complex geometry, outcomes are promising as the fault damaged zone clearly appears as the highest permeability zone, where stress analysis show that the actual stress state may favor tensile reopening of fractures. Using shale samples cored from the different internal structures of the fault zone, we aim now to characterize the advection and diffusion using laboratory petrophysical tests combined with radial and through-diffusion experiments.

Courbet, C.; DICK, P.; Lefevre, M.; Wittebroodt, C.; Matray, J.; Barnichon, J.

2013-12-01

316

Hydraulics.  

ERIC Educational Resources Information Center

These instructional materials provide an orientation to hydraulics for use at the postsecondary level. The first of 12 sections presents an introduction to hydraulics, including discussion of principles of liquids, definitions, liquid flow, the two types of hydraulic fluids, pressure gauges, and strainers and filters. The second section identifies…

Engelbrecht, Nancy; And Others

317

Estimation of hydro-fracture parameters by analysis of tube waves at vertical seismic profiling  

NASA Astrophysics Data System (ADS)

The problem on tube wave excitation in a well intersected by a finite-size fluid-filled crack under action of external seismic wave is considered. This situation appears at vertical seismic profiling (VSP) in the presence of hydro-fracture intersecting the borehole. A heterogeneous integral-differential equation for the fluid pressure field in fracture is derived in the long-wave approximation by the fracture opening. Stitching of the solution for pressure in fracture with that for tube waves in a well allows to calculate the amplitude and shape of generated tube waves. Numerical computations that under action of the external seismic field the crack edges excite a strongly dispersive mode of a thin fluid layer which can be used for estimation of linear fracture size on the basis of VSP technique.

Maksimov, G. A.; Derov, A. V.; Kashtan, B. M.; Lazarkov, M. Yu.

2011-07-01

318

Robust Hydraulic Fracture Monitoring (HFM) of Multiple Time Overlapping Events Using a Generalized Discrete Radon Transform  

E-print Network

In this work we propose a novel algorithm for multiple-event localization for Hydraulic Fracture Monitoring (HFM) through the exploitation of the sparsity of the observed seismic signal when represented in a basis consisting of space time propagators. We provide explicit construction of these propagators using a forward model for wave propagation which depends non-linearly on the problem parameters - the unknown source location and mechanism of fracture, time and extent of event, and the locations of the receivers. Under fairly general assumptions and an appropriate discretization of these parameters we first build an over-complete dictionary of generalized Radon propagators and assume that the data is well represented as a linear superposition of these propagators. Exploiting this structure we propose sparsity penalized algorithms and workflow for super-resolution extraction of time overlapping multiple seismic events from single well data.

Ely, Gregory

2013-01-01

319

On a 2D hydro-mechanical lattice approach for modelling hydraulic fracture  

NASA Astrophysics Data System (ADS)

A 2D lattice approach to describe hydraulic fracturing is presented. The interaction of fluid pressure and mechanical response is described by Biot's theory. The lattice model is applied to the analysis of a thick-walled cylinder, for which an analytical solution for the elastic response is derived. The numerical results obtained with the lattice model agree well with the analytical solution. Furthermore, the coupled lattice approach is applied to the fracture analysis of the thick-walled cylinder. It is shown that the proposed lattice approach provides results that are independent of the mesh size. Moreover, a strong geometrical size effect on nominal strength is observed which lies between analytically derived lower and upper bounds. This size effect decreases with increasing Biot's coefficient.

Grassl, P.; Fahy, C.; Gallipoli, D.; Wheeler, S. J.

2015-02-01

320

Measurement of field-saturated hydraulic conductivity on fractured rock outcrops near Altamura (Southern Italy) with an adjustable large ring infiltrometer  

USGS Publications Warehouse

Up to now, field studies set up to measure field-saturated hydraulic conductivity to evaluate contamination risks, have employed small cylinders that may not be representative of the scale of measurements in heterogeneous media. In this study, a large adjustable ring infiltrometer was designed to be installed on-site directly on rock to measure its field-saturated hydraulic conductivity. The proposed device is inexpensive and simple to implement, yet also very versatile, due to its large adjustable diameter that can be fixed on-site. It thus allows an improved representation of the natural system's heterogeneity, while also taking into consideration irregularities in the soil/rock surface. The new apparatus was tested on an outcrop of karstic fractured limestone overlying the deep Murge aquifer in the South of Italy, which has recently been affected by untreated sludge disposal, derived from municipal and industrial wastewater treatment plants. The quasi-steady vertical flow into the unsaturated fractures was investigated by measuring water levels during infiltrometer tests. Simultaneously, subsurface electrical resistivity measurements were used to visualize the infiltration of water in the subsoil, due to unsaturated water flow in the fractures. The proposed experimental apparatus works well on rock outcrops, and allows the repetition of infiltration tests at many locations in order to reduce model uncertainties in heterogeneous media. ?? 2009 Springer-Verlag.

Caputo, M.C.; de Carlo, L.; Masciopinto, C.; Nimmo, J.R.

2010-01-01

321

Joint location and source mechanism inversion of microseismic events: benchmarking on seismicity induced by hydraulic fracturing  

NASA Astrophysics Data System (ADS)

Seismic monitoring can greatly benefit from imaging events with a low signal-to-noise ratio (SNR) as the number of the events with a low signal grows exponentially. One way to detect weaker events is improvement of a SNR by migration-type stacking of waveforms from multiple stations. We have developed a new method of location of seismic events that involves stacking of seismic phases and amplitudes along diffraction traveltime curves to suppress noise and detect seismic events with a SNR lower than that on individual receivers. The stacking includes polarity correction based on a simultaneous seismic moment tensor inversion and detection algorithm on the stack function. We applied this method to locate microseismicity induced by hydraulic fracturing. First we calibrated the velocity model by locating perforation shots at known locations. Then we processed 3 d of data from microseismic monitoring of shale stimulation and benchmarked migration-type locations of the largest events that were manually located. The detected and located events induced by hydraulic fracturing in this case study are mostly shear events forming narrow bands along the maximum horizontal stress direction approximately 100 m above the injection intervals. The proposed technique is fully automated and feasible for real-time seismic monitoring.

Anikiev, D.; Valenta, J.; Stan?k, F.; Eisner, L.

2014-07-01

322

Microbial communities in flowback water impoundments from hydraulic fracturing for recovery of shale gas  

SciTech Connect

Hydraulic fracturing for natural gas extraction from shale produces waste brine known as flowback that is impounded at the surface prior to reuse and/or disposal. During impoundment, microbial activity can alter the fate of metals including radionuclides, give rise to odorous compounds, and result in biocorrosion that complicates water and waste management and increases production costs. Here, we describe the microbial ecology at multiple depths of three flowback impoundments from the Marcellus shale that were managed differently. 16S rRNA gene clone libraries revealed that bacterial communities in the untreated and biocide-amended impoundments were depth dependent, diverse, and most similar to species within the taxa [gamma]-proteobacteria, [alpha]-proteobacteria, ?-proteobacteria, Clostridia, Synergistetes, Thermotogae, Spirochetes, and Bacteroidetes. The bacterial community in the pretreated and aerated impoundment was uniform with depth, less diverse, and most similar to known iodide-oxidizing bacteria in the [alpha]-proteobacteria. Archaea were identified only in the untreated and biocide-amended impoundments and were affiliated to the Methanomicrobia class. This is the first study of microbial communities in flowback water impoundments from hydraulic fracturing. The findings expand our knowledge of microbial diversity of an emergent and unexplored environment and may guide the management of flowback impoundments.

Mohan, Arvind Murali; Hartsock, Angela; Hammack, Richard W.; Vidic, Radisav D; Gregory, Kelvin B.

2013-12-01

323

Radium and barium removal through blending hydraulic fracturing fluids with acid mine drainage.  

PubMed

Wastewaters generated during hydraulic fracturing of the Marcellus Shale typically contain high concentrations of salts, naturally occurring radioactive material (NORM), and metals, such as barium, that pose environmental and public health risks upon inadequate treatment and disposal. In addition, fresh water scarcity in dry regions or during periods of drought could limit shale gas development. This paper explores the possibility of using alternative water sources and their impact on NORM levels through blending acid mine drainage (AMD) effluent with recycled hydraulic fracturing flowback fluids (HFFFs). We conducted a series of laboratory experiments in which the chemistry and NORM of different mix proportions of AMD and HFFF were examined after reacting for 48 h. The experimental data combined with geochemical modeling and X-ray diffraction analysis suggest that several ions, including sulfate, iron, barium, strontium, and a large portion of radium (60-100%), precipitated into newly formed solids composed mainly of Sr barite within the first ? 10 h of mixing. The results imply that blending AMD and HFFF could be an effective management practice for both remediation of the high NORM in the Marcellus HFFF wastewater and beneficial utilization of AMD that is currently contaminating waterways in northeastern U.S.A. PMID:24367969

Kondash, Andrew J; Warner, Nathaniel R; Lahav, Ori; Vengosh, Avner

2014-01-21

324

Microbial communities in flowback water impoundments from hydraulic fracturing for recovery of shale gas.  

PubMed

Hydraulic fracturing for natural gas extraction from shale produces waste brine known as flowback that is impounded at the surface prior to reuse and/or disposal. During impoundment, microbial activity can alter the fate of metals including radionuclides, give rise to odorous compounds, and result in biocorrosion that complicates water and waste management and increases production costs. Here, we describe the microbial ecology at multiple depths of three flowback impoundments from the Marcellus shale that were managed differently. 16S rRNA gene clone libraries revealed that bacterial communities in the untreated and biocide-amended impoundments were depth dependent, diverse, and most similar to species within the taxa ?-proteobacteria, ?-proteobacteria, ?-proteobacteria, Clostridia, Synergistetes, Thermotogae, Spirochetes, and Bacteroidetes. The bacterial community in the pretreated and aerated impoundment was uniform with depth, less diverse, and most similar to known iodide-oxidizing bacteria in the ?-proteobacteria. Archaea were identified only in the untreated and biocide-amended impoundments and were affiliated to the Methanomicrobia class. This is the first study of microbial communities in flowback water impoundments from hydraulic fracturing. The findings expand our knowledge of microbial diversity of an emergent and unexplored environment and may guide the management of flowback impoundments. PMID:23875618

Murali Mohan, Arvind; Hartsock, Angela; Hammack, Richard W; Vidic, Radisav D; Gregory, Kelvin B

2013-12-01

325

Investigating the potential use of radium isotopes to trace hydraulic fracturing pollution in streams  

NASA Astrophysics Data System (ADS)

In recent years, hydraulic fracturing or 'fracking' to extract petroleum and natural gas from shale deposits has become much more prevalent. There are currently over 25,000 natural gas wells in the U.S., not all presently active, and permits to date allow projections of more drilling until 2020. Many fracking wells are located in close proximity to streams, and anecdotal evidence suggests that fracking and related activities may lead to surface water pollution. However, little data about the environmental impacts of hydraulic fracturing on streams has been collected. This project investigates the novel use of radium and radon, which are widely used to trace groundwater discharge into coastal waters, as indicators of fracking waste. We measured radium, radon, pH, conductivity, Secchi depth, and dissolved metal concentrations in 20 stream sites near fracking wells in western Pennsylvania and 10 comparable sites where fracking does not take place in western Maryland. We assessed broad differences in water quality between Pennsylvania (fracking) and Maryland (control) sites and investigated correlations between these water quality parameters and intensity of fracking. If radium or radon shows promise as a tracer of fracking pollution, we can also use it to better understand how widespread environmental pollution from fracking is and how this pollution is transported in order to detect spills or inadequate treatment at wastewater facilities.

Hitchens, A.; Knee, K.

2013-12-01

326

Rock specific hydraulic fracturing and matrix acidizing to enhance a geothermal system — Concepts and field results  

NASA Astrophysics Data System (ADS)

Enhanced geothermal systems (EGS) are engineered reservoirs developed to extract economic amounts of heat from low permeability and/or porosity geothermal resources. To enhance the productivity of reservoirs, a site specific concept is necessary to actively make reservoir conditions profitable using specially adjusted stimulation treatments, such as multi fracture concepts and site specific well path design. The results of previously performed stimulation treatments in the geothermal research well GtGrSk4/05 at Groß Schönebeck, Germany are presented. The reservoir is located at a 4100-4300 m depth within the Lower Permian of the NE German Basin with a bottom-hole temperature of 150 °C. The reservoir rock is classified by two lithological units from bottom to top: volcanic rocks (andesitic rocks) and siliciclastics ranging from conglomerates to fine-grained sandstones (fluvial sediments). The stimulation treatments included multiple hydraulic stimulations and an acid treatment. In order to initiate a cross-flow from the sandstone layer, the hydraulic stimulations were performed in different depth sections (two in the sandstone section and one in the underlying volcanic section). In low permeability volcanic rocks, a cyclic hydraulic fracturing treatment was performed over 6 days in conjunction with adding quartz in low concentrations to maintain a sustainable fracture performance. Flow rates of up to 150 l/s were realized, and a total of 13,170 m 3 of water was injected. A hydraulic connection to the sandstone layer was successfully achieved in this way. However, monitoring of the water level in the offsetting well EGrSk3/90, which is 475 m apart at the final depth, showed a very rapid water level increase due to the stimulation treatment. This can be explained by a connected fault zone within the volcanic rocks. Two gel-proppant treatments were performed in the slightly higher permeability sandstones to obtain long-term access to the reservoir rocks. During each treatment, a total of 100 ton of high strength proppants was injected with 500 m 3 of cross-linked gel. The subsequent production test in conjunction with flowmeter logging showed an improvement of productivity by a factor of more than 4. Due to assumed residual drilling mud (constituents: calcite, dolomite, and aragonite) in the near-wellbore vicinity, an acid matrix stimulation was performed thereafter using a coil tubing unit. The following nitrogen lift test demonstrated another increase of productivity by 30-50% to an overall increase by a factor of 5.5-6.2.

Zimmermann, Günter; Blöcher, Guido; Reinicke, Andreas; Brandt, Wulf

2011-04-01

327

Assessment of vertical root fracture using cone-beam computed tomography  

PubMed Central

Purpose The aim of this study was to investigate the accuracy of cone-beam computed tomography (CBCT) in the diagnosis of vertical root fractures in a tooth with gutta-percha and prefabricated posts. Materials and Methods This study selected 96 extracted molar and premolar teeth of the mandible. These teeth were divided into six groups as follows: Groups A, B, and C consisted of teeth with vertical root fractures, and groups D, E, and F had teeth without vertical root fractures; groups A and D had teeth with gutta-percha and prefabricated posts; groups B and E had teeth with gutta-percha but without prefabricated posts, and groups C and F had teeth without gutta-percha or prefabricated posts. Then, the CBCT scans were obtained and examined by three oral and maxillofacial radiologists in order to determine the presence of vertical root fractures. The data were analyzed using IBM SPSS 20.0 (IBM Corp., Armonk, NY, USA). Results The kappa coefficient was 0.875±0.049. Groups A and D showed a sensitivity of 81% and a specificity of 100%; groups E and B, a sensitivity of 94% and a specificity of 100%; and groups C and F, a sensitivity of 88% and a specificity of 100%. Conclusion The CBCT scans revealed a high accuracy in the diagnosis of vertical root fractures; the accuracy did not decrease in the presence of gutta-percha. The presence of prefabricated posts also had little effect on the accuracy of the system, which was, of course, not statistically significant. PMID:24701457

Moudi, Ehsan; Haghanifar, Sina; Madani, Zahrasadat; Alhavaz, Abdolhamid; Bijani, Ali

2014-01-01

328

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

SciTech Connect

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 both 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.

Polsky, Yarom [ORNL] [ORNL; Anovitz, Lawrence {Larry} M [ORNL; An, Ke [ORNL] [ORNL; Carmichael, Justin R [ORNL] [ORNL; Bingham, Philip R [ORNL] [ORNL; Dessieux Jr, Luc Lucius [ORNL] [ORNL

2013-01-01

329

Modeling Outburst Flooding as a Turbulent Hydraulic Fracture Parallel to a Nearby Free Surface  

NASA Astrophysics Data System (ADS)

Meltwater generated at the surface and base of glaciers and ice sheets is known to have a large impact on how ice masses behave dynamically, but much is still unknown about the physical processes responsible for how this meltwater drains out of the glacier. For example, little attention has been paid to short-timescale processes like turbulent hydraulic fracture, which is likely an important mechanism by which drainage channels initially form when water pressures are high. In recent work (Tsai and Rice [Fall AGU, 2008; JGR subm., 2009]), we have constructed a model of this turbulent hydraulic fracture process in which over-pressurized water is assumed to flow turbulently through a crack, leading to crack growth. However, one important limitation of this prior work is that it only strictly applies in the limit of short crack length 2L compared to glacier height H, whereas relevant observations of supraglacial lake drainage, jokulhlaups and sub-glacial lake-to-lake transport episodes do not fall in this regime. Here, we improve somewhat upon this model by explicitly accounting for a nearby free surface. We accomplish this by applying the approach of Erdogan et al. [Meth. Anal. Sol. Crack Prob., 1973] to numerically calculate elastic displacements consistent with crack pressure distribution for a crack near a free surface, and use these results as before to simultaneously satisfy the governing fluid, elastic and fracture equations. Our results are analogous to the zero fracture toughness results of Zhang et al. [Int. J. Numer. Anal. Meth. Geomech., 2005], but applied to the case of turbulent flow rather than laminar flow of a Newtonian viscous fluid. Our new results clarify the importance of the free surface and potentially explain discrepancies between our previous modeling results and observations of supraglacial lake drainage by Das et al. [Science, 2008]. However, the numerical challenges increase as 2L becomes comparable to or much larger than H. We hope to ultimately develop simpler analyses for that range which make use of (visco)elastic plate theory at positions along the uplifted ice sheet that are remote from the fracturing front. This approach may also be of interest for tidal interactions with the ice-shelf grounding line location.

Tsai, V. C.; Rice, J. R.

2009-12-01

330

Modeling Outburst Flooding as a Turbulent Hydraulic Fracture Parallel to a Nearby Free Surface  

NASA Astrophysics Data System (ADS)

Meltwater generated at the surface and base of glaciers and ice sheets is known to have a large impact on how ice masses behave dynamically, but much is still unknown about the physical processes responsible for how this meltwater drains out of the glacier. For example, little attention has been paid to short-timescale processes like turbulent hydraulic fracture, which is likely an important mechanism by which drainage channels initially form when water pressures are high. In recent work (Tsai and Rice [Fall AGU, 2008; JGR subm., 2009]), we have constructed a model of this turbulent hydraulic fracture process in which over-pressurized water is assumed to flow turbulently through a crack, leading to crack growth. However, one important limitation of this prior work is that it only strictly applies in the limit of short crack length, 2L, compared to glacier height, H, whereas relevant observations of supraglacial lake drainage, jokulhlaups and sub-glacial lake-to-lake transport episodes do not fall in this regime. Here, we improve somewhat upon this model by explicitly accounting for a nearby free surface. We accomplish this by applying the approach of Erdogan et al. [Meth. Anal. Sol. Crack Prob., 1973] to numerically calculate elastic displacements consistent with crack pressure distribution for a crack near a free surface, and use these results as before to simultaneously satisfy the governing fluid, elastic and fracture equations. Our results are analogous to the zero fracture toughness results of Zhang et al. [Int. J. Numer. Anal. Meth. Geomech., 2005], but applied to the case of turbulent flow rather than laminar flow of a Newtonian viscous fluid. Our new results clarify the importance of the free surface and potentially explain discrepancies between our previous modeling results and observations of supraglacial lake drainage by Das et al. [Science, 2008]. However, the numerical challenges increase as 2L becomes comparable to or much larger than H. We hope to ultimately develop simpler analyses for that range which make use of (visco)elastic plate theory at positions along the uplifted ice sheet that are remote from the fracturing front. This approach may also be of interest for tidal interactions with the ice-shelf grounding line location.

Tsai, Victor; Rice, James

2010-05-01

331

Hydraulics.  

ERIC Educational Resources Information Center

Designed for use in courses where students are expected to become proficient in the area of hydraulics, including diesel engine mechanic programs, this curriculum guide is comprised of fourteen units of instruction. Unit titles include (1) Introduction, (2) Fundamentals of Hydraulics, (3) Reservoirs, (4) Lines, Fittings, and Couplers, (5) Seals,…

Decker, Robert L.

332

4/6/2014 EU Drafts Hydraulic Fracturing Guidelines to Mitigate Conflicting Laws | The DailyEnergyReport http://www.dailyenergyreport.com/eu-drafts-hydraulic-fracturing-guidelines-to-mitigate-conflicting-laws-2/ 1/7  

E-print Network

/eu-drafts-hydraulic-fracturing-guidelines-to-mitigate-conflicting-laws-2/ 2/7 Boeing Looking to Add Diesel From Vegetable Oils to Flights Boeing Co., the largest from vegetable oils to reduce fossil fuel consumption and curb carbon emissions. The "green" diesel the Chicago-based airplane maker. Libya's Oil Expansion Aids Refiners The first expansion in Libya's oil

Chiao, Jung-Chih

333

Field determination of the three-dimensional hydraulic conductivity tensor of anisotropic media 2. Methodology and application to fractured rocks.  

USGS Publications Warehouse

The analytical solutions developed in the first paper can be used to interpret the results of cross-hole tests conducted in anisotropic porous or fractured media. Test results from a granitic rock near Oracle in southern Arizona are presented to illustrate how the method works for fractured rocks. At the site, the Oracle granite is shown to respond as a near-uniform, anisotropic medium, the hydraulic conductivity of which is strongly controlled by the orientations of major fracture sets. The cross-hole test results are shown to be consistent with the results of more than 100 single- hole packer tests conducted at the site. -from Authors

Hsieh, P.A.; Neuman, S.P.; Stiles, G.K.; Simpson, E.S.

1985-01-01

334

Estimation of deformation and stiffness of fractures close to tunnels using data from single-hole hydraulic testing and grouting  

SciTech Connect

Sealing of tunnels in fractured rocks is commonly performed by pre- or post-excavation grouting. The grouting boreholes are frequently drilled close to the tunnel wall, an area where rock stresses can be low and fractures can more easily open up during grout pressurization. In this paper we suggest that data from hydraulic testing and grouting can be used to identify grout-induced fracture opening, to estimate fracture stiffness of such fractures, and to evaluate its impact on the grout performance. A conceptual model and a method are presented for estimating fracture stiffness. The method is demonstrated using grouting data from four pre-excavation grouting boreholes at a shallow tunnel (50 m) in Nygard, Sweden, and two post-excavation grouting boreholes at a deep tunnel (450 m) in Aespoe HRL, Sweden. The estimated stiffness of intersecting fractures for the boreholes at the shallow Nygard tunnel are low (2-5 GPa/m) and in agreement with literature data from field experiments at other fractured rock sites. Higher stiffness was obtained for the deeper tunnel boreholes at Aespoe which is reasonable considering that generally higher rock stresses are expected at greater depths. Our method of identifying and evaluating the properties and impact of deforming fractures might be most applicable when grouting takes place in boreholes adjacent to the tunnel wall, where local stresses might be low and where deforming (opening) fractures may take most of the grout.

Fransson, A.; Tsang, C.-F.; Rutqvist, J.; Gustafson, G.

2010-05-01

335

A method to allow temporal variation of velocity in travel-time tomography using microearthquakes induced during hydraulic fracturing  

Microsoft Academic Search

Hydraulic injections produce fluid-filled fractures that reduce the seismic velocity of the rock compared to intact rock. The travel times of microearthquakes induced by the injections may be used to discern changes in the rock velocities, as well as locating the microearthquakes. Determining the volumes of rock where the velocities have changed provides indirect evidence for the location of the

Michael Fehler; Leigh House; W. Scott Phillips; Robert Potter

1998-01-01

336

Acoustic Emissions as a Tool for Hydraulic Fracture Location: Experience at the Fenton Hill Hot Dry Rock Site  

Microsoft Academic Search

Microearthquakes with magnitudes between -6 and -2 have been observed in three successive massive injections of water at the hot dry rock geothermal energy development project's demonstration site at Fenton Hill, NM. The injections were part of a program to increase the heat transfer area of hydraulic fractures and to decrease the flow-through impedance between wells in the energy extraction

James Albright; Christopher Pearson

1982-01-01

337

EXPERIMENTAL ANALYSIS OF THE ENVIRONMENTAL BEHAVIOR OF HYDRAULIC FRACTURING FLUID COMPOUNDS PRIORITIZED BY POTENTIAL OF ENVIRONMENTAL OR HEALTH RISK  

EPA Science Inventory

Given the large number of chemical additives used in hydraulic fracturing fluids, it is not practical to conduct a comprehensive analysis in cases where contamination is suspected. The fate and transport model can identify compounds with high likelihood for transport and pe...

338

Seismic wave motion for a new model of hydraulic fracture with an induced low-velocity zone  

Microsoft Academic Search

Hydraulic fracture treatments induce microsensitivity (i.e., discrete events plus noise) which can be recorded only by seismometers located in or near the treatment well bore. Seismograms recorded in the treatment well bore are composed of interacting phases which to data defay discrete identification and preclude standard inversion techniques to determine source characteristics, propagation path characteristics, or both. To understand the

Kenneth D. Mahrer; Frederick J. Mauk

1987-01-01

339

Parameters and a magnitude moment relationship from small earthquakes observed during hydraulic fracturing experiments in crystalline rocks  

Microsoft Academic Search

Using source parameters estimated from seismic spectra and magnitudes estimated from coda lengths, we demonstrate that the log-linear relationship between moment and magnitude holds for events with magnitudes as low as -6. Using, as a data set, events induced by hydraulic fracturing experiments at the Fenton Hill, New Mexico, Hot Dry Rock (HDR) geothermal site, we find that the relationship

C. Pearson

1982-01-01

340

Analysis of Best Hydraulic Fracturing Practices in the Golden Trend Fields of Oklahoma Shahab D. Mohaghegh, West Virginia University  

E-print Network

Analysis of Best Hydraulic Fracturing Practices in the Golden Trend Fields of Oklahoma Shahab D best practices analysis methodology. The study was performed for gas and oil bearing formations. Among to perform the best practices analysis on the Golden Trend fields of Oklahoma is presented. CONCLUSIONS Wells

Mohaghegh, Shahab

341

The distinct element analysis for hydraulic fracturing in hard rock considering fluid viscosity and particle size distribution  

Microsoft Academic Search

A series of simulations for hydraulic fracturing in competent rock was performed by using the flow-coupled DEM code to discuss the influence of the fluid viscosity and the particle size distribution. The simulation results show good agreement with experimental results that contain the AE measurement data. The following observations can be made. When a low viscosity fluid is used, the

Hiroyuki Shimizu; Sumihiko Murata; Tsuyoshi Ishida

2011-01-01

342

On the effective hydraulic conductivity in mean vertical unsaturated steady flows  

NASA Astrophysics Data System (ADS)

Water flow in partially saturated heterogeneous porous formations is modelled by regarding the hydraulic parameters as stationary random space functions (RSFs). As a consequence, the flow variables are also RSFs, and we aim to develop a procedure to derive the effective hydraulic conductivity (EHC). The methodology relies on a perturbation approach which regards the variances of the hydraulic parameters as small quantities. By using the Gardner's [Gardner WR. Some steady state solutions of unsaturated moisture flow equations with application to evaporation from a water table. Soil Sci 1958;85:228-32] two-parameters ( Ks, ?) model for the local unsaturated conductivity, we obtain the EHC for any dimensionality d of the flow domain, and arbitrary correlation functions of the input RSFs. Unlike previous studies [e.g. Yeh T-CJ, Gelhar J, Gutjahr A. Stochastic analysis of unsaturated flow in heterogenous soils. 1. Statistically isotropic media. Water Resour Res 1985;21;447-56, Yeh T-CJ, Gelhar J, Gutjahr A. Stochastic analysis of unsaturated flow in heterogenous soils. 2. Statistically anisotropic media with variable ?. Water Resour Res 1985:21:457-64], the EHC is represented here as product between the local scale conductivity valid for a domain of mean parameters, and a correction function ?? which depends on the medium heterogeneity structure and the mean pressure head. Generally, the correction function ?? is expressed by d-fold quadrature. These quadratures are further reduced after adopting specific (i.e. exponential and Gaussian) structure for the (cross) correlation functions involved in the computation of ??. We have also focused on some particular formation structures which are relevant for the applications, and permit simplification of the computational aspect, as well. We investigate effects of the heterogeneity formation properties as well as the mean head on the structure of ??. Overall, results suggest that, given the formation statistics, the impact of the heterogeneity upon ?? is enhanced as the medium becomes drier. This is particularly so when the variability of the fluctuation of Y = ln Ks is small compared with that of ? = ln ?. Conversely, when the heterogeneity of Y is prevalent upon that of ?, ?? is influenced solely by the anisotropic structure of the formation unless the horizontal correlation scales are much greater than the vertical ones.

Severino, Gerardo; Santini, Alessandro

2005-09-01

343

Risks to biodiversity from hydraulic fracturing for natural gas in the Marcellus and Utica shales.  

PubMed

High-volume horizontal hydraulic fracturing (HVHHF) for mining natural gas from the Marcellus and Utica shales is widespread in Pennsylvania and potentially throughout approximately 280,000 km(2) of the Appalachian Basin. Physical and chemical impacts of HVHHF include pollution by toxic synthetic chemicals, salt, and radionuclides, landscape fragmentation by wellpads, pipelines, and roads, alteration of stream and wetland hydrology, and increased truck traffic. Despite concerns about human health, there has been little study of the impacts on habitats and biota. Taxa and guilds potentially sensitive to HVHHF impacts include freshwater organisms (e.g., brook trout, freshwater mussels), fragmentation-sensitive biota (e.g., forest-interior breeding birds, forest orchids), and species with restricted geographic ranges (e.g., Wehrle's salamander, tongue-tied minnow). Impacts are potentially serious due to the rapid development of HVHHF over a large region. PMID:23701448

Kiviat, Erik

2013-05-01

344

Community-based risk assessment of water contamination from high-volume horizontal hydraulic fracturing.  

PubMed

The risk of contaminating surface and groundwater as a result of shale gas extraction using high-volume horizontal hydraulic fracturing (fracking) has not been assessed using conventional risk assessment methodologies. Baseline (pre-fracking) data on relevant water quality indicators, needed for meaningful risk assessment, are largely lacking. To fill this gap, the nonprofit Community Science Institute (CSI) partners with community volunteers who perform regular sampling of more than 50 streams in the Marcellus and Utica Shale regions of upstate New York; samples are analyzed for parameters associated with HVHHF. Similar baseline data on regional groundwater comes from CSI's testing of private drinking water wells. Analytic results for groundwater (with permission) and surface water are made publicly available in an interactive, searchable database. Baseline concentrations of potential contaminants from shale gas operations are found to be low, suggesting that early community-based monitoring is an effective foundation for assessing later contamination due to fracking. PMID:23552652

Penningroth, Stephen M; Yarrow, Matthew M; Figueroa, Abner X; Bowen, Rebecca J; Delgado, Soraya

2013-01-01

345

Vertical Open Patella Fracture, Treatment, Rehabilitation and the Moment to Fixation  

PubMed Central

Patella fracture is relatively uncommon and the vertical trace fracture represents almost 12-17%. The open patella fracture expresses 6-30%. The association of these two uncommon conditions was the aim of this case report even as the treatment and the moment of fixation (definitive surgical treatment). A 27-year-old man after a motorcycle accident showed an open patella fracture classified as a Gustilo and Anderson type IIIA lesion. The patient was immediately treated with precocious surgery fixation with a modified tension band which consists of two parallel K-wires positioned orthogonal to the fracture line and a cerclage wire shaped anteriorly at patella as an eight. The premature fixation benefited the infection prevention and provided earlier joint motion, which increased the nutrition of articular cartilage. Six months postoperatively, the patient had a satisfactory joint motion with full extension and 116° of joint flexion and returned to his daily life activities without restriction. Twelve months postoperatively, the patient had full extension and 120° of knee flexion without pain, joint effusion and instability. Muscle strength force was considered normal at grade V. In conclusion, early chirurgic treatment and precocious articular mobilization improve prognosis, suggesting that the employment of these practices should be adopted whenever possible in most of the open fractures. PMID:25436033

Larangeira, Joao Alberto; Bellenzier, Liliane; Rigo, Vanessa da Silva; Ramos Neto, Elias Josue; Krum, Francisco Fritsch Machry; Ribeiro, Tiango Aguiar

2015-01-01

346

Vertical open patella fracture, treatment, rehabilitation and the moment to fixation.  

PubMed

Patella fracture is relatively uncommon and the vertical trace fracture represents almost 12-17%. The open patella fracture expresses 6-30%. The association of these two uncommon conditions was the aim of this case report even as the treatment and the moment of fixation (definitive surgical treatment). A 27-year-old man after a motorcycle accident showed an open patella fracture classified as a Gustilo and Anderson type IIIA lesion. The patient was immediately treated with precocious surgery fixation with a modified tension band which consists of two parallel K-wires positioned orthogonal to the fracture line and a cerclage wire shaped anteriorly at patella as an eight. The premature fixation benefited the infection prevention and provided earlier joint motion, which increased the nutrition of articular cartilage. Six months postoperatively, the patient had a satisfactory joint motion with full extension and 116° of joint flexion and returned to his daily life activities without restriction. Twelve months postoperatively, the patient had full extension and 120° of knee flexion without pain, joint effusion and instability. Muscle strength force was considered normal at grade V. In conclusion, early chirurgic treatment and precocious articular mobilization improve prognosis, suggesting that the employment of these practices should be adopted whenever possible in most of the open fractures. PMID:25436033

Larangeira, Joao Alberto; Bellenzier, Liliane; Rigo, Vanessa da Silva; Ramos Neto, Elias Josue; Krum, Francisco Fritsch Machry; Ribeiro, Tiango Aguiar

2015-02-01

347

A comparison of electrical and electromagnetic methods for the detection of hydraulic pathways in a fractured rock aquifer, Clare Valley, South Australia  

Microsoft Academic Search

Within fractured rock, the irregular and often unpredictable distribution and geometry of hydraulically conductive fractures produces large spatial variations in bore yield and groundwater quality. As fractures act as conduits for flow of both groundwater and electrical charge, methods which can efficiently detect the distribution of electrical pathways can be used to infer characteristics of significant hydrological parameters. This study

Damien Skinner; Graham Heinson

2004-01-01

348

Quantitative Metrics of Soil Structure and Relationships to Hydraulic Properties in a Vertic Argiudoll  

E-print Network

to soil hydraulic parameters, especially saturated hydraulic conductivity (Ks) and water retention curve (WRC) parameters. Soil moisture data collected at the lysimeter, in conjunction with atmospheric data from an adjacent tower, were used as inputs...

Eck, Dennis V.

2014-05-31

349

New treatment option for an incomplete vertical root fracture--a preliminary case report.  

PubMed

Instead of extraction this case report presents an alternative treatment option for a maxillary incisor with a vertical root fracture (VRF) causing pain in a 78-year-old patient. After retreatment of the existing root canal filling the tooth was stabilized with a dentine adhesive and a composite restoration. Then the tooth was extracted, the VRF gap enlarged with a small diamond bur and the existing retrograde root canal filling removed. The enlarged fracture line and the retrograde preparation were filled with a calcium-silicate-cement (Biodentine). Afterwards the tooth was replanted and a titanium trauma splint was applied for 12d. A 24 months clinical and radiological follow-up showed an asymptomatic tooth, reduction of the periodontal probing depths from 7 mm prior to treatment to 3 mm and gingival reattachment in the area of the fracture with no sign of ankylosis. Hence, the treatment of VRF with Biodentine seems to be a possible and promising option. PMID:24670232

Hadrossek, Paul Henryk; Dammaschke, Till

2014-01-01

350

Effect of new obturating materials on vertical root fracture resistance of endodontically treated teeth.  

PubMed

The aim of this study was to compare vertical forces at fracture of teeth obturated with different materials. Single-rooted teeth were divided into five groups. The first group served as a negative control. The remaining four groups were shaped using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland). The second group was obturated with gutta percha and a zinc oxide sealer. The third group was obturated with EndoRez points and EndoRez sealer (both from Ultradent, South Jordan, UT). The fourth group was obturated with Resilon (Pentron Clinical Technologies, Wallingford, CT) and RealSeal sealer (Pentron Clinical Technologies). The fifth group was obturated with Guttaflow (Colténe/Whaledent, Altstätten, Switzerland). Roots were then fixed into a universal testing machine and loaded with a spreader until fracture. It was found that forces at fracture were statistically significantly higher in the Resilon and EndoRez groups. It was concluded that obturation of roots with resin-based obturation materials (Resilon and EndoRez) increased the resistance of root canal filled teeth to vertical root fracture. PMID:17509416

Hammad, Mohammad; Qualtrough, Alison; Silikas, Nick

2007-06-01

351

Vertical Root Fracture: Preservation of the Alveolar Ridge Using Immediate Implants  

PubMed Central

Teeth with vertical root fracture (VRF) have complete or incomplete fractures that begin in the root and extend toward the occlusal surface. The most frequent causes of VRF originate from physical trauma, occlusal prematurity, inadequate endodontic treatment, and iatrogenic causes. Diagnose is difficult and delay can cause stomatognathic system problem. The purpose of this case report was to evaluate immediate implant placement after extraction of teeth with vertical root fracture. For the 1st case, the VRF in 1st left lower molar was confirmed during surgical flap and at the same time, the tooth was removed and immediate implant was placed. For the 2nd case, the VRF 1st left lower molar was confirmed during endodontic access and at the same appointment, the tooth was removed and the immediate implant is placed. Several studies have shown that immediate implants have similar success rates when compared with late implants. Consider that this approach is a safe procedure with favorable prognosis. In cases of VRF, the main factor to be considered is the presence of adequate bone support and immediate implants can preserve the vertical bone height, adding the fact that good patient compliance reduces the number of surgical interventions and promotes the functionality of stomatognathic system. PMID:24715996

Oya, Edmar de Oliveira; Pallos, Debora; Schwartz-Filho, Humberto Osvaldo; Brandt, William Cunha; Sendyk, Wilson Roberto; Roman-Torres, Caio Vinicius Gonçalves

2014-01-01

352

Hydraulic fracturing in unconventional reservoirs - Identification of hazards and strategies for a quantitative risk assessment  

NASA Astrophysics Data System (ADS)

The production of unconventional gas resources, which require a fracking process to be released, such as shale gas, tight gas and coal bed methane, has become an economically attractive technology for a continued supply of fossil-fuel energy sources in many countries. Just recently, a major focus of interest has been directed to hydraulic fracking in Germany. The technology is controversial since it involves severe risks. The main difference in risk with respect to other technologies in the subsurface such as carbon sequestration is that fracking is remunerative, and it is important to distinguish between economical and environmental issues. The hydrofracking process may pose a threat to groundwater resources if fracking fluid or brine can migrate through fault zones into shallow aquifers. Diffuse methane emissions from the gas reservoir may not only contaminate shallow groundwater aquifers but also escape into the atmosphere where methane acts as a greenhouse gas. The working group "Risks in the Geological System" as part of ExxonMobil's hydrofracking dialogue and information dissemination processes was tasked with the assessment of possible hazards posed by migrating fluids as a result of hydrofracking activities. In this work several flow paths for fracking fluid, brine and methane are identified and scenarios are set up to qualitatively estimate under what circumstances these fluids would leak into shallower layers. The parametrization for potential fracking sites in North Rhine-Westphalia and Lower Saxony (both in Germany) is derived from literature using upper and lower bounds of hydraulic parameters. The results show that a significant fluid migration is only possible if a combination of several conservative assumptions are met by a scenario. Another outcome of this work is the demand for further research, as many of the involved processes in the hydrofracking process have yet not been fully understood (e.g. quantification of source terms for methane in the fractured reservoir, fracture propagation, fault zones and their role in regard to fluid migration into shallow aquifers). A quantitative risk assessment which should be the main aim of future work in this field has much higher demands, especially on site specific data, as the estimation of statistical parameter uncertainty requires site specific parameter distributions. There is already ongoing research on risk assessment in related fields like CO2 sequestration. We therefore propose these methodologies to be transferred to risk estimation relating to the use of the hydraulic fracking method, be it for unconventional gas or enhanced geothermal energy production. The overall aim should be to set common and transparent standards for different uses of the subsurface and their involved risks and communicate those to policy makers and stake holders.

Helmig, R.; Kissinger, A.; Class, H.; Ebigbo, A.

2012-12-01

353

Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel.  

PubMed

A steam injection pilot-scale experiment was performed on the unsaturated zone of a strongly heterogeneous fractured soil contaminated by jet fuel. Before the treatment, the soil was stimulated by creating sub-horizontal sand-filled hydraulic fractures at three depths. The steam was injected through one hydraulic fracture and gas/water/non-aqueous phase liquid (NAPL) was extracted from the remaining fractures by applying a vacuum to extraction wells. The injection strategy was designed to maximize the heat delivery over the entire cell (10 m × 10 m × 5 m). The soil temperature profile, the recovered NAPL, the extracted water, and the concentrations of volatile organic compounds (VOCs) in the gas phase were monitored during the field test. GC-MS chemical analyses of pre- and post-treatment soil samples allowed for the quantitative assessment of the remediation efficiency. The growth of the heat front followed the configuration of hydraulic fractures. The average concentration of total hydrocarbons (g/kg of soil) was reduced by ? 43% in the upper target zone (depth = 1.5-3.9 m) and by ? 72% over the entire zone (depth = 1.5-5.5 m). The total NAPL mass removal based on gas and liquid stream measurements and the free-NAPL product were almost 30% and 2%, respectively, of those estimated from chemical analyses of pre- and post-treatment soil samples. The dominant mechanisms of soil remediation was the vaporization of jet fuel compounds at temperatures lower than their normal boiling points (steam distillation) enhanced by the ventilation of porous matrix due to the forced convective flow of air. In addition, the significant reduction of the NAPL mass in the less-heated deeper zone may be attributed to the counter-current imbibition of condensed water from natural fractures into the porous matrix and the gravity drainage associated with seasonal fluctuations of the water table. PMID:21030134

Nilsson, Bertel; Tzovolou, Dimitra; Jeczalik, Maciej; Kasela, Tomasz; Slack, William; Klint, Knud E; Haeseler, Frank; Tsakiroglou, Christos D

2011-03-01

354

Techniques for measuring the vertical hydraulic conductivity of flood basalts at the Basalt Waste Isolation Project site  

SciTech Connect

A regional model that can predict groundwater movement through the reference repository location and surrounding area is essential to assessing the site suitability for a nuclear waste repository. During the last two decades, several models have been developed to handle complicated flow patterns through complex geologic materials. The basic problem, however, is obtaining the data base needed to apply these models. The hydrological data needed include the spatial distribution of effective porosity, the hydraulic conductivity tensor and its variation in space, values of specific storage, the hydraulic head distribution, and the fluid properties. In this report, we discuss conventional methods of obtaining vertical hydraulic conductivity and examine their applicability to the BWIP site. 39 references, 12 figures, 4 tables.

Javandel, I.

1983-06-01

355

Experimental Study of the Propagation of a Hydraulic Fracture Containing a Constant Volume of Buoyant, Viscous Fluid  

NASA Astrophysics Data System (ADS)

We present the results of laboratory experiments whose ultimate aim is to contribute to understanding the propagation of magma-filled fractures in the Earth's lithosphere. The immediate goal is to verify physical models of simpler systems before building in greater complexity. We study the propagation of isothermal, hydraulic fractures, containing differing but constant volumes of fluid, in elastic, brittle solid. The flows are driven by buoyancy of the fluid with respect to the solid and have low Reynolds Numbers. Fluids are Newtonian and the solid hosting the fractures is gelatin with isotropic homogeneous elastic properties. Elastic modulus and fracture toughness vary between experiments. We present a visualization technique enabling us to measure the opening profile of the fissure and hence deduce the profile of elastic pressure during propagation. We highlight two results: First, propagation speed is not constant, but steadily decreases as the fractures lengthen. Numerical calculations of fracture propagation in two dimensions suggest that length should increase like (time)^{1/3}, whereas experimentally we observe a range of exponents from 0.05 to 0.5. Second, fractures eventually stop at some final length despite the fact that the buoyancy pressure based on total fracture length should (using a 2-dimensional argument) be enough to continue fracturing the solid. Our experimental data on the final lengths and widths of fractures can be correlated by a dimensionless parameter constructed from the fluid buoyancy, the released volume, and on the fracture toughness of the solid. These scaling laws suggest that the arrest of fractures in the Earth's lithosphere on these purely mechanical grounds could be a common occurrence. This result implies that for given rock properties and magma reservoir depth, there should be a minimum volume threshold necessary for eruption to occur.

Taisne, B.; Tait, S.; Craster, R.

2006-12-01

356

Combined interpretation of radar, hydraulic, and tracer data from a fractured-rock aquifer near Mirror Lake, New Hampshire, USA  

USGS Publications Warehouse

An integrated interpretation of field experimental cross-hole radar, tracer, and hydraulic data demonstrates the value of combining time-lapse geophysical monitoring with conventional hydrologic measurements for improved characterization of a fractured-rock aquifer. Time-lapse difference-attenuation radar tomography was conducted during saline tracer experiments at the US Geological Survey Fractured Rock Hydrology Research Site near Mirror Lake, Grafton County, New Hampshire, USA. The presence of electrically conductive saline tracer effectively illuminates permeable fractures or pathways for geophysical imaging. The geophysical results guide the construction of three-dimensional numerical models of ground-water flow and solute transport. In an effort to explore alternative explanations for the tracer and tomographic data, a suite of conceptual models involving heterogeneous hydraulic conductivity fields and rate-limited mass transfer are considered. Calibration data include tracer concentrations, the arrival time of peak concentration at the outlet, and steady-state hydraulic head. Results from the coupled inversion procedure suggest that much of the tracer mass migrated outside the three tomographic image planes, and that solute is likely transported by two pathways through the system. This work provides basic and site-specific insights into the control of permeability heterogeneity on ground-water flow and solute transport in fractured rock. ?? Springer-Verlag 2004.

Day-Lewis, F. D.; Lane, J.W., Jr.; Gorelick, S.M.

2006-01-01

357

Hydraulics  

NSDL National Science Digital Library

These interactive learning objects, created by instructors from Fox Valley Technical College and other colleges in the Wisconsin Technical College program, focus on concepts that cover a broad-based electromechanical program. Here visitors will find learning objects in Hydraulics with over 25 lessons in Actuators, Relief Valves, Basic Concepts, and Directional Control Valves.

358

Bonded half-planes containing two arbitrarily oriented cracks: A study of containment of hydraulically induced fractures  

SciTech Connect

In the first part of this paper, the title subject is studied by introducing two modified singular integrals. The problem is reduced to a set of singular integral equations; and it is solved numerically by employing the LobattoChebyshev method. The stress intensity factor at the fracture tips of a hydraulically induced fracture in a layered medium is calculated in the second part of the paper. The effect of the fluid pressure and the in-situ stress gradient as well as the effect of the relative layer material properties on the magnitude of the stress intensity factors are studied numerically. It has been shown that the relative magnitude of the stress intensity factor at the fracture tips can be used to indicate the direction of fracture movement.

Lu, C.; Yew, C.H.

1985-02-01

359

Geophysical assessment of the hydraulic property of the fracture systems around Lake Nasser-Egypt: In sight of polarimetric borehole radar  

NASA Astrophysics Data System (ADS)

Hydraulic property of the subsurface structures is a complicated mission. In this work, the polarimetric analysis for the measured dataset applied by the polarimetric borehole radar system in order to delineate the characteristics of subsurface fractures. Two different locations in USA and Egypt were selected to perform our investigation. The first polarimetric dataset has been acquired at Mirror Lake, USA which is well known as a standard site for testing the hydraulic properties of subsurface fractures (Sato et al., 1999). The results show the presence of nine fracture zones in one borehole FSE-1. The hydraulic properties were detected and the subsurface fractures were differentiated into four categories fracture zones after deriving the radar polarimetric analysis of alpha, entropy and anisotropy parameters at 30 MHz frequency. The fracture zones at 24.75, 47.8 and 55.2 m depths have the highest hydraulic transmissivity while the fracture zones at 28.5, 36.15 m have the lowest hydraulic transmissivity. These results show a good consistency with the hydraulic permeability tracer test and the structures exist in the area. Similarly, we used the same technique to characterize the subsurface fracture systems detected by geoelectric and geomagnetic methods around Lake Nasser in Egypt using the previous results of Mirror Lake as a key guide. The results show a great correlation with detected structures prevailed in the sedimentary and basement rocks. These results illustrate an ideal explanation for the prevailed subsurface structures and the recharging of the main Nubian sandstone aquifer from Lake Nasser. Also, these results also show that the northeast fracture zone trends are most probably having the highest hydraulic transmissivity whereas the northwest fracture zones have the lowest one. The integration of surface geophysical measurements with the polarimetric borehole radar and the polarimetric analysis of its datasets introduce better understanding of the recharging mechanism between surface water and the subsurface aquifer and also can be used as clue for identifying the subsurface structures for different areas.

Mansour, Khamis; Basheer, Alhussein A.; Rabeh, Taha; Khalil, Ahmed; Eldin, A. A. Essam; Sato, Motoyuki

2014-06-01

360

Vertical anisotropy of hydraulic conductivity in the fissured layer of hard-rock aquifers due to the geological structure of weathering profiles  

E-print Network

1 Vertical anisotropy of hydraulic conductivity in the fissured layer of hard-rock aquifers due the transmissive function in the aquifer and is pumped by most of the wells drilled in hard-rock areas; - Fresh

Paris-Sud XI, Université de

361

Long-Period Oscillations of Hydraulic Fractures: Attenuation, Scaling Relationships, and Flow Stability  

NASA Astrophysics Data System (ADS)

Long-period seismicity due to the excitation of hydraulic fracture normal modes is thought to occur in many geological systems, including volcanoes, glaciers and ice sheets, and hydrocarbon reservoirs. To better quantify the physical dimensions of fluid-filled cracks and properties of the fluid within them, we study wave motion along a thin hydraulic fracture waveguide. We present a linearized analysis that accounts for quasi-dynamic elasticity of the fracture wall, as well as fluid drag, inertia, and compressibility. We consider symmetric perturbations and neglect the effects of stratification and gravity. In the long-wavelength or thin-fracture limit, dispersive guided waves known as crack waves propagate with phase velocity cw=?(G*|k|w/?), where G* = G/(1-?) for shear modulus G and Poisson ratio ?, w is the crack half-width, k is the wavenumber, and ? is the fluid density. Restoring forces from elastic wall deformation drive wave motions. In the opposite, short-wavelength limit, guided waves are simply sound waves within the fluid and little seismic excitation occurs due to minimal fluid-solid coupling. We focus on long-wavelength crack waves, which, in the form of standing wave modes in finite-length cracks, are thought to be a common mechanism for long-period seismicity. The dispersive nature of crack waves implies several basic scaling relations that might be useful when interpreting statistics of long-period events. Seismic observations may constrain a characteristic frequency f0 and seismic moment M0~G?wR2, where ?w is the change in crack width and R is the crack dimension. Resonant modes of a fluid-filled crack have associated frequencies f~cw/R. Linear elasticity provides a link between pressure changes ?p in the crack and the induced opening ?w: ?p~G ?w/R. Combining these, and assuming that pressure changes have no variation with crack dimension, leads to the scaling law relating seismic moment and oscillation frequency, M0~(Gw?p/?)f0-2. This contrasts with the well-known self-similar earthquake scaling M0?f0-3. Attenuation of long-period crack waves is due to both drag within the fluid and radiative energy losses from excitation of seismic waves. Fluid drag may be characterized by either a turbulent or laminar viscous law. We present a thorough characterization of viscous damping that is valid at both low frequencies, where the flow is always fully developed, and at high frequencies, where fluid inertia becomes important. We have derived simple formulas for the quality factor due to viscous attenuation. Waves may become unstable for sufficiently fast background fluid velocity u0. This instability, first proposed by Julian (1994), was further investigated by Dunham and Ogden (2012), who determined the instability condition, u0>cw/2. We establish a more general result: that the stability condition is not only independent of viscosity, but also uninfluenced by fluid inertia, although both do alter growth rates. We also show that radiation damping (excitation of plane P waves normal to the crack walls) has only a stabilizing effect. This work suggests that under geologically relevant conditions, crack wave propagation is most likely stable, and the occurrence of long-period oscillations thus requires some additional excitation process.

Lipovsky, B.; Dunham, E. M.

2013-12-01

362

Development of Rapid Radiochemical Method for Gross Alpha and Gross Beta Activity Concentration in Flowback and Produced Waters from Hydraulic Fracturing Operations  

EPA Science Inventory

This report summarizes the development and validation of an improved method for the Determination of Gross Alpha and Gross Beta Activity in Flowback and Produced Waters from Hydraulic Fracturing Operations (FPWHFO). Flowback and produced waters are characterized by high concentra...

363

Polyelectrolyte Complex Nanoparticles for Protection and Delayed Release of Enzymes in Alkaline pH and at Elevated Temperature during Hydraulic Fracturing of Oil Wells  

E-print Network

Polyethylenimine-dextran sulfate polyelectrolyte complexes (PEC) were used to entrap two enzymes used to degrade polymer gels following hydraulic fracturing of oil wells in order to obtain delayed release and to protect the enzyme from harsh...

Barati Ghahfarokhi, Reza; Johnson, Stephen J.; McCool, Stan; Green, Don W.; Willhite, G. Paul; Liang, Jenn-Tai

2012-01-01

364

Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing.  

PubMed

Directional drilling and hydraulic-fracturing technologies are dramatically increasing natural-gas extraction. In aquifers overlying the Marcellus and Utica shale formations of northeastern Pennsylvania and upstate New York, we document systematic evidence for methane contamination of drinking water associated with shale-gas extraction. In active gas-extraction areas (one or more gas wells within 1 km), average and maximum methane concentrations in drinking-water wells increased with proximity to the nearest gas well and were 19.2 and 64 mg CH(4) L(-1) (n = 26), a potential explosion hazard; in contrast, dissolved methane samples in neighboring nonextraction sites (no gas wells within 1 km) within similar geologic formations and hydrogeologic regimes averaged only 1.1 mg L(-1) (P < 0.05; n = 34). Average ?(13)C-CH(4) values of dissolved methane in shallow groundwater were significantly less negative for active than for nonactive sites (-37 ± 7‰ and -54 ± 11‰, respectively; P < 0.0001). These ?(13)C-CH(4) data, coupled with the ratios of methane-to-higher-chain hydrocarbons, and ?(2)H-CH(4) values, are consistent with deeper thermogenic methane sources such as the Marcellus and Utica shales at the active sites and matched gas geochemistry from gas wells nearby. In contrast, lower-concentration samples from shallow groundwater at nonactive sites had isotopic signatures reflecting a more biogenic or mixed biogenic/thermogenic methane source. We found no evidence for contamination of drinking-water samples with deep saline brines or fracturing fluids. We conclude that greater stewardship, data, and-possibly-regulation are needed to ensure the sustainable future of shale-gas extraction and to improve public confidence in its use. PMID:21555547

Osborn, Stephen G; Vengosh, Avner; Warner, Nathaniel R; Jackson, Robert B

2011-05-17

365

Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing  

PubMed Central

Directional drilling and hydraulic-fracturing technologies are dramatically increasing natural-gas extraction. In aquifers overlying the Marcellus and Utica shale formations of northeastern Pennsylvania and upstate New York, we document systematic evidence for methane contamination of drinking water associated with shale-gas extraction. In active gas-extraction areas (one or more gas wells within 1 km), average and maximum methane concentrations in drinking-water wells increased with proximity to the nearest gas well and were 19.2 and 64 mg CH4 L-1 (n = 26), a potential explosion hazard; in contrast, dissolved methane samples in neighboring nonextraction sites (no gas wells within 1 km) within similar geologic formations and hydrogeologic regimes averaged only 1.1 mg L-1 (P < 0.05; n = 34). Average ?13C-CH4 values of dissolved methane in shallow groundwater were significantly less negative for active than for nonactive sites (-37 ± 7‰ and -54 ± 11‰, respectively; P < 0.0001). These ?13C-CH4 data, coupled with the ratios of methane-to-higher-chain hydrocarbons, and ?2H-CH4 values, are consistent with deeper thermogenic methane sources such as the Marcellus and Utica shales at the active sites and matched gas geochemistry from gas wells nearby. In contrast, lower-concentration samples from shallow groundwater at nonactive sites had isotopic signatures reflecting a more biogenic or mixed biogenic/thermogenic methane source. We found no evidence for contamination of drinking-water samples with deep saline brines or fracturing fluids. We conclude that greater stewardship, data, and—possibly—regulation are needed to ensure the sustainable future of shale-gas extraction and to improve public confidence in its use. PMID:21555547

Osborn, Stephen G.; Vengosh, Avner; Warner, Nathaniel R.; Jackson, Robert B.

2011-01-01

366

Directional hydraulic behavior of a fractured-shale aquifer in New Jersey  

USGS Publications Warehouse

The principal source of ground water throughout a large part of central and northeastern New Jersey is the aquifer in the Brunswick Shale -- the youngest unity of the Newark Group of Triassic Age. Large-diameter public-supply and industrial wells tapping the Brunswick Shale commonly yield several hundred gallons per minute each. Virtually all ground water in this aquifer occurs in interconnecting fractures; the formation has practically no effective primary porosity. Numerous pumping tests have shown that the aquifer exhibits directional, rather than isotropic, hydraulic behavior. Water levels in wells alined along the strike of the formation show greater magnitude of interference than those in wells alined in transverse directions. Drawdown data evaluated by standard time-drawdown methods indicate computed coefficient of transmissibility in all cases is least in the direction of strike. Because of the distribution of observation wells available for the tests, distance-drawdown methods of evaluation could be used in only one instance -- for just one direction; the computed coefficient compared favorably with that calculated from the time-drawdown method. Computed values of transmissibility may be unreliable owing to the departure of the aquifer from the ideal model. It is even possible that the direction of minimum computed transmissiblity is actually indicative of the alinement of fractures with the greatest permeability. However, the relation of the directional behavior to the structure of the formation has practical significance when locating the new wells near existing wells. Well interference can be greatly minimized, generally, by alining wells perpendicular to the strike.

Vecchioli, John

1965-01-01

367

Assessing the risk of groundwater contamination posed by hydraulic fracturing through the use of a fault tree assisted numerical model  

NASA Astrophysics Data System (ADS)

Shale gas exploitation in the United States is an increasingly important resource, since 2007 the production of shale gas has increased at an average annual rate of 44%. The increasing importance of shale gas to U.S. energy production and energy security necessitates an appropriate risk assessment of all processes of hydraulic fracturing to ensure its continued safety. This paper seeks to address the methodology needed to develop a quantitative risk assessment of hydraulic fracturing on subsurface aquifers using a fault tree in conjunction with a numerical model. The model incorporates geologic uncertainty through the use of a Monte Carlo simulation. The workflow of the model is presented through the use of a case study site within the Marcellus Shale.

Montague, J.; Pinder, G. F.

2013-12-01

368

Strontium isotopes test long-term zonal isolation of injected and Marcellus formation water after hydraulic fracturing.  

PubMed

One concern regarding unconventional hydrocarbon production from organic-rich shale is that hydraulic fracture stimulation could create pathways that allow injected fluids and deep brines from the target formation or adjacent units to migrate upward into shallow drinking water aquifers. This study presents Sr isotope and geochemical data from a well-constrained site in Greene County, Pennsylvania, in which samples were collected before and after hydraulic fracturing of the Middle Devonian Marcellus Shale. Results spanning a 15-month period indicated no significant migration of Marcellus-derived fluids into Upper Devonian/Lower Mississippian units located 900-1200 m above the lateral Marcellus boreholes or into groundwater sampled at a spring near the site. Monitoring the Sr isotope ratio of water from legacy oil and gas wells or drinking water wells can provide a sensitive early warning of upward brine migration for many years after well stimulation. PMID:25024106

Kohl, Courtney A Kolesar; Capo, Rosemary C; Stewart, Brian W; Wall, Andrew J; Schroeder, Karl T; Hammack, Richard W; Guthrie, George D

2014-08-19

369

3d hydraulic fracture propagation in the presence of stress variations  

Microsoft Academic Search

A model of three dimensional fracture propagation in blanket sands bounded by higher-stress zones is described. The comparative effects of stress contrast, fracture toughness, and elastic modules on fracture shape and bottomhole pressure are examined. Some preliminary modeling of fracture propagation in a lenticular gas sand are also considered briefly. The goal of this work is to investigate how fracture

I. D. Palmer; H. B. Jr. Caroll

1982-01-01

370

Hydraulic stimulation of natural fractures as revealed by induced microearthquakes, Carthage Cotton Valley gas field, east Texas  

Microsoft Academic Search

ABSTRACT Wehave,produced a high-resolution microseismic image of a hydraulic fracture stimulation in the Carthage Cotton Valley gas field of east Texas. Gas is produced from multiple, low-permeability sands within an interbedded sand-shale sequence. We improved the precision of microseismic event locations 4-fold over initial locations by manually repicking the waveforms,in a spatial sequence, allowing us to visually correlate waveforms of

James T. Rutledge; W. Scott Phillips

2003-01-01

371

Application of hydraulic fracturing to determine virgin in situ stress state around Waste Isolation Pilot Plant - in situ measurements  

Microsoft Academic Search

Hydraulic fracturing tests were carried out in horizontal drillholes in rock salt in the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. It was determined that the virgin in situ stress field is isotropic or nearly isotropic. The inferred magnitude of the isotropic in situ stress falls between bounds of 14.28 MPa and 17.9 MPa for the average breakdown\\/reopening pressures

W. R. Wawersik; C. M. Stone

1985-01-01

372

Cooperative federalism and hydraulic fracturing: a human right to a clean environment.  

PubMed

This Article argues that filling the energy governance gaps regarding unconventional natural gas can best be accomplished through collaborative governance that is genuinely adaptive and cooperative. Through cooperative federalism, combined with procedural rights for inclusive, innovative decision-making, state and non-state actors should design and implement the requisite safeguards before further natural gas development advances. Hydraulic fracturing provisions are strikingly fragmented and have sparked a fierce debate about chemical disclosure, radioactive wastewater disposal, and greenhouse gas emissions. United States natural gas production may stunt the direction and intensity of renewable energy by up to two decades and will not provide a bridge to a sound energy policy if it "erode[s] efforts to prepare a landing at the other end of the bridge." Unconventional natural gas extraction need not become a transition to a new addiction. This Article analyzes how cooperative federalism and inclusive decision-making can provide legitimacy and transparency when balancing property rights against police powers to regulate natural gas production. PMID:25330564

Burleson, Elizabeth

2012-01-01

373

Using discriminant analysis to determine sources of salinity in shallow groundwater prior to hydraulic fracturing.  

PubMed

High-volume hydraulic fracturing (HVHF) gas-drilling operations in the Marcellus Play have raised environmental concerns, including the risk of groundwater contamination. Fingerprinting water impacted by gas-drilling operations is not trivial given other potential sources of contamination. We present a multivariate statistical modeling framework for developing a quantitative, geochemical fingerprinting tool to distinguish sources of high salinity in shallow groundwater. The model was developed using new geochemical data for 204 wells in New York State (NYS), which has a HVHF moratorium and published data for additional wells in NYS and several salinity sources (Appalachian Basin brines, road salt, septic effluent, and animal waste). The model incorporates a stochastic simulation to predict the geochemistry of high salinity (>20 mg/L Cl) groundwater impacted by different salinity sources and then employs linear discriminant analysis to classify samples from different populations. Model results indicate Appalachian Basin brines are the primary source of salinity in 35% of sampled NYS groundwater wells with >20 mg/L Cl. The model provides an effective means for differentiating groundwater impacted by basin brines versus other contaminants. Using this framework, similar discriminatory tools can be derived for other regions from background water quality data. PMID:25062431

Lautz, Laura K; Hoke, Gregory D; Lu, Zunli; Siegel, Donald I; Christian, Kayla; Kessler, John Daniel; Teale, Natalie G

2014-08-19

374

Physical, chemical, and biological characteristics of compounds used in hydraulic fracturing.  

PubMed

Hydraulic fracturing (HF), a method to enhance oil and gas production, has become increasingly common throughout the U.S. As such, it is important to characterize the chemicals found in HF fluids to evaluate potential environmental fate, including fate in treatment systems, and human health impacts. Eighty-one common HF chemical additives were identified and categorized according to their functions. Physical and chemical characteristics of these additives were determined using publicly available chemical information databases. Fifty-five of the compounds are organic and twenty-seven of these are considered readily or inherently biodegradable. Seventeen chemicals have high theoretical chemical oxygen demand and are used in concentrations that present potential treatment challenges. Most of the HF chemicals evaluated are non-toxic or of low toxicity and only three are classified as Category 2 oral toxins according to standards in the Globally Harmonized System of Classification and Labeling of Chemicals; however, toxicity information was not located for thirty of the HF chemicals evaluated. Volatilization is not expected to be a significant exposure pathway for most HF chemicals. Gaps in toxicity and other chemical properties suggest deficiencies in the current state of knowledge, highlighting the need for further assessment to understand potential issues associated with HF chemicals in the environment. PMID:24853136

Stringfellow, William T; Domen, Jeremy K; Camarillo, Mary Kay; Sandelin, Whitney L; Borglin, Sharon

2014-06-30

375

Ground gas monitoring: implications for hydraulic fracturing and CO2 storage.  

PubMed

Understanding the exchange of carbon dioxide (CO2) and methane (CH4) between the geosphere and atmosphere is essential for the management of anthropogenic emissions. Human activities such as carbon capture and storage and hydraulic fracturing ("fracking") affect the natural system and pose risks to future global warming and to human health and safety if not engineered to a high standard. In this paper an innovative approach of expressing ground gas compositions is presented, using data derived from regulatory monitoring of boreholes in the unsaturated zone at infrequent intervals (typically 3 months) with data from a high frequency monitoring instrument deployed over periods of weeks. Similar highly variable trends are observed for time scales ranging from decades to hourly for boreholes located close to sanitary landfill sites. Additionally, high frequency monitoring data confirm the effect of meteorological controls on ground gas emissions; the maximum observed CH4 and CO2 concentrations in a borehole monitored over two weeks were 40.1% v/v and 8.5% v/v respectively, but for 70% of the monitoring period only air was present. There is a clear weakness in current point monitoring strategies that may miss emission events and this needs to be considered along with obtaining baseline data prior to starting any engineering activity. PMID:25363162

Teasdale, Christopher J; Hall, Jean A; Martin, John P; Manning, David A C

2014-12-01

376

Source and fate of hydraulic fracturing water in the Barnett Shale: a historical perspective.  

PubMed

Considerable controversy continues about water availability for and potential impacts of hydraulic fracturing (HF) of hydrocarbon assets on water resources. Our objective was to quantify HF water volume in terms of source, reuse, and disposal, using the Barnett Shale in Texas as a case study. Data were obtained from commercial and state databases, river authorities, groundwater conservation districts, and operators. Cumulative water use from ? 18,000 (mostly horizontal) wells since 1981 through 2012 totaled ? 170,000 AF (210 Mm(3)); ? 26 000 AF (32 Mm(3)) in 2011, representing 32% of Texas HF water use and ? 0.2% of 2011 state water consumption. Increase in water use per well by 60% (from 3 to 5 Mgal/well; 0.011-0.019 Mm(3)) since the mid-2000s reflects the near-doubling of horizontal-well lengths (2000-3800 ft), offset by a reduction in water-use intensity by 40% (2000-1200 gal/ft; 2.5-1.5 m(3)/m). Water sources include fresh surface water and groundwater in approximately equal amounts. Produced water amount is inversely related to gas production, exceeds HF water volume, and is mostly disposed in injection wells. Understanding the historical evolution of water use in the longest-producing shale play is invaluable for assessing its water footprint for energy production. PMID:24467212

Nicot, Jean-Philippe; Scanlon, Bridget R; Reedy, Robert C; Costley, Ruth A

2014-02-18

377

Dispersion analysis of passive surface-wave noise generated during hydraulic-fracturing operations  

NASA Astrophysics Data System (ADS)

Surface-wave dispersion analysis is useful for estimating near-surface shear-wave velocity models, designing receiver arrays, and suppressing surface waves. Here, we analyze whether passive seismic noise generated during hydraulic-fracturing operations can be used to extract surface-wave dispersion characteristics. Applying seismic interferometry to noise measurements, we extract surface waves by cross-correlating several minutes of passive records; this approach is distinct from previous studies that used hours or days of passive records for cross-correlation. For comparison, we also perform dispersion analysis for an active-source array that has some receivers in common with the passive array. The active and passive data show good agreement in the dispersive character of the fundamental-mode surface-waves. For the higher mode surface waves, however, active and passive data resolve the dispersive properties at different frequency ranges. To demonstrate an application of dispersion analysis, we invert the observed surface-wave dispersion characteristics to determine the near-surface, one-dimensional shear-wave velocity.

Forghani-Arani, Farnoush; Willis, Mark; Snieder, Roel; Haines, Seth S.; Behura, Jyoti; Batzle, Mike; Davidson, Michael

2014-12-01

378

Characterizing fractured rock aquifers using heated Distributed Fiber-Optic Temperature Sensing to determine borehole vertical flow  

NASA Astrophysics Data System (ADS)

In highly heterogeneous media, fracture network connectivity and hydraulic properties can be estimated using methods such as packer- or cross-borehole pumping-tests. Typically, measurements of hydraulic head or vertical flow in such tests are made either at a single location over time, or at a series of depths by installing a number of packers or raising or lowering a probe. We show how this often encountered monitoring problem, with current solutions sacrificing either one of temporal or spatial information, can be addressed using Distributed Temperature Sensing (DTS). Here, we electrically heat the conductive cladding materials of cables deployed in boreholes to determine the vertical flow profile. We present results from heated fiber optic cables deployed in three boreholes in a fractured rock aquifer at the much studied experimental site near Ploemeur, France, allowing detailed comparisons with alternative methods (e.g. Le Borgne et al., 2007). When submerged in water and electrically heated, the cable very rapidly reaches a steady state temperature (less than 60 seconds). The steady state temperature of the heated cable, measured using the DTS method, is then a function of the velocity of the fluid in the borehole. We find that such cables are sensitive to a wide range of fluid velocities, and thus suitable for measuring both ambient and pumped flow profiles at the Ploemeur site. The cables are then used to monitor the flow profiles during all possible configurations of: ambient flow, cross-borehole- (pumping one borehole, and observing in another), and dipole-tests (pumping one borehole, re-injection in another). Such flow data acquired using DTS may then be used for tomographic flow inversions, for instance using the approach developed by Klepikova et al., (submitted). Using the heated fiber optic method, we are able to observe the flow response during such tests in high spatial detail, and are also able to capture temporal flow dynamics occurring at the start of both the pumping and recovery phase of cross-borehole- and dipole- tests. In addition, the clear advantage of this is that by deploying a single fiber optic cable in multiple boreholes at a site, the flow profiles in all boreholes can be simultaneously measured, allowing many different pumping experiments to be conducted and monitored in a time efficient manner. Klepikova M. V., Le Borgne T., Bour O., and J-R.de Dreuzy, Inverse modelling of flow tomography experiments in fractured media, submitted to Water Resources Research. Le Borgne T., Bour O., Riley M. S., Gouze P., Pezard P.A., Belghoul A., Lods G., Le Provost R., Greswell R. B., Ellis P.A., Isakov E., and B. J. Last, Comparison of alternative methodologies for identifying and characterizing preferential flow paths in heterogeneous aquifers. Journal of Hydrology 2007, 345, 134-148.

Read, T. O.; Bour, O.; Selker, J. S.; Le Borgne, T.; Bense, V.; Hochreutener, R.; Lavenant, N.

2013-12-01

379

Temporal changes in microbial ecology and geochemistry in produced water from hydraulically fractured Marcellus shale gas wells.  

PubMed

Microorganisms play several important roles in unconventional gas recovery, from biodegradation of hydrocarbons to souring of wells and corrosion of equipment. During and after the hydraulic fracturing process, microorganisms are subjected to harsh physicochemical conditions within the kilometer-deep hydrocarbon-bearing shale, including high pressures, elevated temperatures, exposure to chemical additives and biocides, and brine-level salinities. A portion of the injected fluid returns to the surface and may be reused in other fracturing operations, a process that can enrich for certain taxa. This study tracked microbial community dynamics using pyrotag sequencing of 16S rRNA genes in water samples from three hydraulically fractured Marcellus shale wells in Pennsylvania, USA over a 328-day period. There was a reduction in microbial richness and diversity after fracturing, with the lowest diversity at 49 days. Thirty-one taxa dominated injected, flowback, and produced water communities, which took on distinct signatures as injected carbon and electron acceptors were attenuated within the shale. The majority (>90%) of the community in flowback and produced fluids was related to halotolerant bacteria associated with fermentation, hydrocarbon oxidation, and sulfur-cycling metabolisms, including heterotrophic genera Halolactibacillus, Vibrio, Marinobacter, Halanaerobium, and Halomonas, and autotrophs belonging to Arcobacter. Sequences related to halotolerant methanogenic genera Methanohalophilus and Methanolobus were detected at low abundance (<2%) in produced waters several months after hydraulic fracturing. Five taxa were strong indicators of later produced fluids. These results provide insight into the temporal trajectory of subsurface microbial communities after "fracking" and have important implications for the enrichment of microbes potentially detrimental to well infrastructure and natural gas fouling during this process. PMID:24803059

Cluff, Maryam A; Hartsock, Angela; MacRae, Jean D; Carter, Kimberly; Mouser, Paula J

2014-06-01

380

Buoyant convection resulting from dissolution and permeability growth in vertical limestone fractures  

NASA Astrophysics Data System (ADS)

Upward flow through vertical fractures in limestone formations under a geothermal gradient favors dissolution and permeability growth. We investigate the transition from conductive and forced convective regimes to instability and buoyant convection as a result of permeability growth. The onset time for instability and roll height at onset depend on the initial aperture and driving pressure. A modified Rayleigh number criterion is proposed, which provides a unified interpretation of the instability across a wide range of initial aperture and driving pressure. Interaction between buoyant convection and aperture alteration leads to narrow upward flow paths supporting dissolution and precipitation in surrounding downward flow regions.

Chaudhuri, A.; Rajaram, H.; Viswanathan, H.; Zyvoloski, G.; Stauffer, P.

2009-02-01

381

Spatial and temporal correlation of water quality parameters of produced waters from devonian-age shale following hydraulic fracturing.  

PubMed

The exponential increase in fossil energy production from Devonian-age shale in the Northeastern United States has highlighted the management challenges for produced waters from hydraulically fractured wells. Confounding these challenges is a scant availability of critical water quality parameters for this wastewater. Chemical analyses of 160 flowback and produced water samples collected from hydraulically fractured Marcellus Shale gas wells in Pennsylvania were correlated with spatial and temporal information to reveal underlying trends. Chloride was used as a reference for the comparison as its concentration varies with time of contact with the shale. Most major cations (i.e., Ca, Mg, Sr) were well-correlated with chloride concentration while barium exhibited strong influence of geographic location (i.e., higher levels in the northeast than in southwest). Comparisons against brines from adjacent formations provide insight into the origin of salinity in produced waters from Marcellus Shale. Major cations exhibited variations that cannot be explained by simple dilution of existing formation brine with the fracturing fluid, especially during the early flowback water production when the composition of the fracturing fluid and solid-liquid interactions influence the quality of the produced water. Water quality analysis in this study may help guide water management strategies for development of unconventional gas resources. PMID:23425120

Barbot, Elise; Vidic, Natasa S; Gregory, Kelvin B; Vidic, Radisav D

2013-03-19

382

The influence of metallic posts in the detection of vertical root fractures using different imaging examinations  

PubMed Central

Objectives: To assess the influence of metallic posts in the detection of simulated vertical root fractures (VRFs) using the following imaging examinations: 2 cone beam CT (CBCT) systems [CBCT1: NewTom® 3G (QR Srl, Verona, Italy) and CBCT2: i-CAT Next Generation® (Imaging Sciences International, Hatfield, PA)] and film and digital radiographs. Additionally, the influence of the orientation of the fracture line in the detection of VRFs was evaluated. Methods: 100, human, single-rooted endodontically treated premolars were divided into 5 groups (Group 1: with posts and buccolingual VRFs, Group 2: with posts and mesiodistal VRFs, Group 3: without posts and with buccolingual VRFs, Group 4: without posts and with mesiodistal VRFs, and Group 5: with posts and without VRFs). The premolars were placed in human mandibles and imaged using the four examination modalities. The sensitivity and the specificity of each examination in the experimental groups were calculated. The data were analysed using Student's t-test. Results: The presence of metallic posts reduced the sensitivity of the CBCT1 system (p = 0.0244). Digital radiographs and the CBCT1 and CBCT2 systems had a higher sensitivity in detecting buccolingual fractures in teeth with posts, whereas film and digital radiographs had a higher sensitivity in detecting buccolingual fractures in teeth without posts (p < 0.05). The CBCT1 examination demonstrated the lowest specificity (p < 0.05). Conclusions: The presence of metallic posts did not influence the sensitivity of most of the examinations, excluding the CBCT1 system. The fracture line orientation may influence VRF detection. PMID:24191261

Jakobson, S J M; Westphalen, V P D; Silva Neto, U X; Fariniuk, L F; Schroeder, A G D

2014-01-01

383

Infiltration and hydraulic connections from the Niagara River to a fractured-dolomite aquifer in Niagara Falls, New York  

USGS Publications Warehouse

The spatial distribution of hydrogen and oxygen stable-isotope values in groundwater can be used to distinguish different sources of recharge and to trace groundwater flow directions from recharge boundaries. This method can be particularly useful in fractured-rock settings where multiple lines of evidence are required to delineate preferential flow paths that result from heterogeneity within fracture zones. Flow paths delineated with stable isotopes can be combined with hydraulic data to form a more complete picture of the groundwater flow system. In this study values of ??D and ??18O were used to delineate paths of river-water infiltration into the Lockport Group, a fractured dolomite aquifer, and to compute the percentage of fiver water in groundwater samples from shallow bedrock wells. Flow paths were correlated with areas of high hydraulic diffusivity in the shallow bedrock that were delineated from water-level fluctuations induced by diurnal stage fluctuations in man-made hydraulic structures. Flow paths delineated with the stable-isotope and hydraulic data suggest that fiver infiltration reaches an unlined storm sewer in the bedrock through a drainage system that surrounds aqueducts carrying river water to hydroelectric power plants. This finding is significant because the storm sewer is the discharge point for contaminated groundwater from several chemical waste-disposal sites and the cost of treating the storm sewer's discharge could be reduced if the volume of infiltration from the river were decreased.The spatial distribution of hydrogen and oxygen stable-isotope values in groundwater can be used to distinguish different sources of recharge and to trace groundwater flow directions from recharge boundaries. This method can be particularly useful in fractured-rock settings where multiple lines of evidence are required to delineate preferential flow paths that result from heterogeneity within fracture zones. Flow paths delineated with stable isotopes can be combined with hydraulic data to form a more complete picture of the groundwater flow system. In this study values of ??D and ??18O were used to delineate paths of river-water infiltration into the Lockport Group, a fractured dolomite aquifer, and to compute the percentage of river water in groundwater samples from shallow bedrock wells. Flow paths were correlated with areas of high hydraulic diffusivity in the shallow bedrock that were delineated from water-level fluctuations induced by diurnal stage fluctuations in man-made hydraulic structures. Flow paths delineated with the stable-isotope and hydraulic data suggest that river infiltration reaches an unlined storm sewer in the bedrock through a drainage system that surrounds aqueducts carrying river water to hydroelectric power plants. This finding is significant because the storm sewer is the discharge point for contaminated groundwater from several chemical waste-disposal sites and the cost of treating the storm sewer's discharge could be reduced if the volume of infiltration from the river were decreased.

Yager, R.M.; Kappel, W.M.

1998-01-01

384

Drill Cuttings-based Methodology to Optimize Multi-stage Hydraulic Fracturing in Horizontal Wells and Unconventional Gas Reservoirs  

NASA Astrophysics Data System (ADS)

Horizontal drilling and hydraulic fracturing techniques have become almost mandatory technologies for economic exploitation of unconventional gas reservoirs. Key to commercial success is minimizing the risk while drilling and hydraulic fracturing these wells. Data collection is expensive and as a result this is one of the first casualties during budget cuts. As a result complete data sets in horizontal wells are nearly always scarce. In order to minimize the data scarcity problem, the research addressed throughout this thesis concentrates on using drill cuttings, an inexpensive direct source of information, for developing: 1) A new methodology for multi-stage hydraulic fracturing optimization of horizontal wells without any significant increases in operational costs. 2) A new method for petrophysical evaluation in those wells with limited amount of log information. The methods are explained using drill cuttings from the Nikanassin Group collected in the Deep Basin of the Western Canada Sedimentary Basin (WCSB). Drill cuttings are the main source of information for the proposed methodology in Item 1, which involves the creation of three 'log tracks' containing the following parameters for improving design of hydraulic fracturing jobs: (a) Brittleness Index, (b) Measured Permeability and (c) An Indicator of Natural Fractures. The brittleness index is primarily a function of Poisson's ratio and Young Modulus, parameters that are obtained from drill cuttings and sonic logs formulations. Permeability is measured on drill cuttings in the laboratory. The indication of natural fractures is obtained from direct observations on drill cuttings under the microscope. Drill cuttings are also the main source of information for the new petrophysical evaluation method mentioned above in Item 2 when well logs are not available. This is important particularly in horizontal wells where the amount of log data is almost non-existent in the vast majority of the wells. By combining data from drill cuttings and previously available empirical relationships developed from cores it is possible to estimate water saturations, pore throat apertures, capillary pressures, flow units, porosity (or cementation) exponent m, true formation resistivity Rt, distance to a water table (if present), and to distinguish the contributions of viscous and diffusion-like flow in the tight gas formation. The method further allows the construction of Pickett plots using porosity and permeability obtained from drill cuttings, without previous availability of well logs. The method assumes the existence of intervals at irreducible water saturation, which is the case of the Nikanassin Group throughout the gas column. The new methods mentioned above are not meant to replace the use of detailed and sophisticated evaluation techniques. But the proposed methods provide a valuable and practical aid in those cases where geomechanical and petrophysical information are scarce.

Ortega Mercado, Camilo Ernesto

385

Propagation of a plane-strain hydraulic fracture with a fluid lag: Early-time solution  

Microsoft Academic Search

This paper studies the propagation of a plane-strain fluid-driven fracture with a fluid lag in an elastic solid. The fracture is driven by a constant rate of injection of an incompressible viscous fluid at the fracture inlet. The leak-off of the fracturing fluid into the host solid is considered negligible. The viscous fluid flow is lagging behind an advancing fracture

Dmitry I. Garagash

2006-01-01

386

Detection of vertical root fractures in endodontically treated teeth by a cone beam computed tomography scan.  

PubMed

Our aim was to compare the accuracy of cone beam computed tomography (CBCT) scans and periapical radiographs (PRs) in detecting vertical root fractures (VRFs) and to assess the influence of root canal filling (RCF) on fracture visibility. Eighty teeth were endodontically prepared and divided into four groups. The teeth in groups A and B were artificially fractured, and teeth in groups C and D were not. Groups A and C were root filled. Four observers evaluated the CBCT scans and PR images. Sensitivity and specificity for VRF detection of CBCT were 79.4% and 92.5% and for PR were 37.1% and 95%, respectively. The specificity of CBCT was reduced (p = 0.032) by the presence of RCF, but its overall accuracy was not influenced (p = 0.654). Both the sensitivity (p = 0.006) and overall accuracy (p = 0.008) of PRs were reduced by the presence of RCF. The results showed an overall higher accuracy for CBCT (0.86) scans than PRs (0.66) for detecting VRF. PMID:19410091

Hassan, Bassam; Metska, Maria Elissavet; Ozok, Ahmet Rifat; van der Stelt, Paul; Wesselink, Paul Rudolf

2009-05-01

387

Analysis of the results of hydraulic-fracture stimulation of two crystalline bedrock boreholes, Grand Portage, Minnesota  

USGS Publications Warehouse

Hydraulic fracture-stimulation procedures typical of those provided by contractors in the water-well industry were applied to two boreholes in basaltic and gabbroic rocks near Grand Portage, Minnesota.These boreholes were considered incapable of supplying adequate ground water for even a single household although geophysical logs showed both boreholes were intersected by many apparently permeable fractures. Tests made before and after stimulation indicated that the two boreholes would produce about 0.05 and 0.25 gallon per minute before stimulation, and about 1.5 and 1.2 gallons per minute after stimulation. These increases would be enough to obtain adequate domestic water supplies from the two boreholes but would not furnish enough water for more than a single household from either borehole. Profiles of high-resolution flow made during pumping after stimulation indicated that the stimulation enhanced previously small inflows or stimulated new inflow from seven fractures or fracture zones in one borehole and from six fractures or fracture zones in the other.Geophysical logs obtained after stimulation showed no specific changes in these 13 fractures that could be related to stimulation other than the increases in flow indicated by the flowmeter logs. The results indicate that the stimulation has increased inflow to the two boreholes by improving the connectivity of favorably orientated fractures with larger scale flow zones in the surrounding rocks. Three of four possible diagnostics related to measured pressure and flow during the stimulation treatments were weakly correlated with the increases in production associated with each treatment interval. These correlations are not statistically significant on the basis of the limited sample of 16 treatment intervals in two boreholes, but the results indicate that significant correlations might be established from a much larger data set.

Paillet, Fredrick L.; Olson, James D.

1994-01-01

388

Thermal and Hydraulic Coupled Modeling of Hot Fractured Rock Geothermal Reservoir  

NASA Astrophysics Data System (ADS)

Geothermal energy manifests itself in spectacular fashion in many places on the earth's surface and has been widely recognized as a renewable green energy in the world. Several countries have started the related projects for developing the Hot Dry Rock (HDR) geothermal system which has been renamed as Hot Fractured Rock (HFR) in Australia. Geodynamics Limited is developing a world-class, high-grade geothermal energy resource beneath the Cooper Basin in NE South Australia, where the measured surface heat flow is over 100mW/m2. It is thought to originate from the Big Lake Suite granites that are enriched in the heat-producing elements. The presence of highly radiogenic intrusive within 3-4 km of the surface generates extraordinarily high geothermal gradient regimes (>60ºC km-1, and the region is recognized as one of the hottest spots in the world outside volcanic centres. To help bringing the vision of HFR geothermal energy to reality, a 3D finite element based computational model and software for simulating such a multi-scale highly coupled thermo- hydro-mechanical geo-mechanical system on the parallel supercomputer are being developed based on our long tern and on-going related outcomes. This presentation will focus on the related outcomes on the thermo- hydro coupling module aiming to investigate thermal and fluid flow coupled process and their impact on the Cooper Basin HFR geothermal reservoir. The microseismicity monitoring data measured during the hydraulic stimulation process was used to estimate the related key input parameters for the further numerical investigation of the coupled thermal and fluid flow behaviours of Cooper Basin HFR geothermal reservoir. The above preliminary simulation results demonstrate the stability and usefulness of the algorithm and software.

Xu, H.; Xing, H.; Wyborn, D.; Yin, C.; Mora, P.

2006-12-01

389

Will water scarcity in semiarid regions limit hydraulic fracturing of shale plays?  

NASA Astrophysics Data System (ADS)

There is increasing concern about water constraints limiting oil and gas production using hydraulic fracturing (HF) in shale plays, particularly in semiarid regions and during droughts. Here we evaluate HF vulnerability by comparing HF water demand with supply in the semiarid Texas Eagle Ford play, the largest shale oil producer globally. Current HF water demand (18 billion gallons, bgal; 68 billion liters, bL in 2013) equates to ?16% of total water consumption in the play area. Projected HF water demand of ?330 bgal with ?62 000 additional wells over the next 20 years equates to ?10% of historic groundwater depletion from regional irrigation. Estimated potential freshwater supplies include ?1000 bgal over 20 yr from recharge and ?10 000 bgal from aquifer storage, with land-owner lease agreements often stipulating purchase of freshwater. However, pumpage has resulted in excessive drawdown locally with estimated declines of ?100–200 ft in ?6% of the western play area since HF began in 2009–2013. Non-freshwater sources include initial flowback water, which is ?5% of HF water demand, limiting reuse/recycling. Operators report shifting to brackish groundwater with estimated groundwater storage of 80 000 bgal. Comparison with other semiarid plays indicates increasing brackish groundwater and produced water use in the Permian Basin and large surface water inputs from the Missouri River in the Bakken play. The variety of water sources in semiarid regions, with projected HF water demand representing ?3% of fresh and ?1% of brackish water storage in the Eagle Ford footprint indicates that, with appropriate management, water availability should not physically limit future shale energy production.

Scanlon, Bridget R.; Reedy, Robert C.; Nicot, Jean Philippe

2014-12-01

390

Comparison of water use for hydraulic fracturing for unconventional oil and gas versus conventional oil.  

PubMed

We compared water use for hydraulic fracturing (HF) for oil versus gas production within the Eagle Ford shale. We then compared HF water use for Eagle Ford oil with Bakken oil, both plays accounting for two-thirds of U.S. unconventional oil production in 2013. In the Eagle Ford, we found similar average water use in oil and gas zones per well (4.7-4.9 × 10(6) gallons [gal]/well). However, about twice as much water is used per unit of energy (water-to-oil ratio, WOR, vol water/vol oil) in the oil zone (WOR: 1.4) as in the gas zone (water-to-oil-equivalent-ratio, WOER: 0.6). We also found large differences in water use for oil between the two plays, with mean Bakken water use/well (2.0 × 10(6) gal/well) about half that in the Eagle Ford, and a third per energy unit. We attribute these variations mostly to geological differences. Water-to-oil ratios for these plays (0.6-1.4) will further decrease (0.2-0.4) based on estimated ultimate oil recovery of wells. These unconventional water-to-oil ratios (0.2-1.4) are within the lower range of those for U.S. conventional oil production (WOR: 0.1-5). Therefore, the U.S. is using more water because HF has expanded oil production, not because HF is using more water per unit of oil production. PMID:25233450

Scanlon, B R; Reedy, R C; Nicot, J-P

2014-10-21

391

Enhancing Seismic Monitoring Capability for Hydraulic Fracturing Induced Seismicity in Canada  

NASA Astrophysics Data System (ADS)

The amount of natural gas produced from unconventional sources, such as the shale gas, has increased dramatically since the last decade. One of the key factors in the success of shale gas production is the application of hydraulic fracturing (also known as "fracking") to facilitate the efficient recovery of natural gas from shale matrices. As the fracking operation becomes routine in all major shale gas fields, its potential to induce local earthquakes at some locations has become a public concern. To address this concern, Natural Resources Canada has initiated a research effort to investigate the potential links between fracking operations and induced seismicity in some major shale gas basins of Canada. This federal-provincial collaborative research aims to assess if shale gas fracking can alter regional pattern of background seismicity and if so, what the relationship between how fracking is conducted and the maximum magnitude of induced seismicity would be. Other objectives include the investigation of the time scale of the interaction between fracking events and induced seismicity and the evaluation of induced seismicity potential for shale gas basins under different tectonic/geological conditions. The first phase of this research is to enhance the detection and monitoring capability for seismicity possibly related to shale gas recovery in Canada. Densification of the Canadian National Seismograph Network (CNSN) is currently underway in northeast British Columbia where fracking operations are taking place. Additional seismic stations are planned for major shale gas basins in other regions where fracking might be likely in the future. All newly established CNSN stations are equipped with broadband seismographs with real-time continuous data transmission. The design goal of the enhanced seismic network is to significantly lower the detection threshold such that the anticipated low-magnitude earthquakes that might be related to fracking operations can be identified and located shortly after their occurrence.

Kao, H.; Cassidy, J. F.; Farahbod, A.; Lamontagne, M.

2012-12-01

392

The functional potential of microbial communities in hydraulic fracturing source water and produced water from natural gas extraction characterized by metagenomic sequencing.  

PubMed

Microbial activity in produced water from hydraulic fracturing operations can lead to undesired environmental impacts and increase gas production costs. However, the metabolic profile of these microbial communities is not well understood. Here, for the first time, we present results from a shotgun metagenome of microbial communities in both hydraulic fracturing source water and wastewater produced by hydraulic fracturing. Taxonomic analyses showed an increase in anaerobic/facultative anaerobic classes related to Clostridia, Gammaproteobacteria, Bacteroidia and Epsilonproteobacteria in produced water as compared to predominantly aerobic Alphaproteobacteria in the fracturing source water. The metabolic profile revealed a relative increase in genes responsible for carbohydrate metabolism, respiration, sporulation and dormancy, iron acquisition and metabolism, stress response and sulfur metabolism in the produced water samples. These results suggest that microbial communities in produced water have an increased genetic ability to handle stress, which has significant implications for produced water management, such as disinfection. PMID:25338024

Mohan, Arvind Murali; Bibby, Kyle J; Lipus, Daniel; Hammack, Richard W; Gregory, Kelvin B

2014-01-01

393

The Functional Potential of Microbial Communities in Hydraulic Fracturing Source Water and Produced Water from Natural Gas Extraction Characterized by Metagenomic Sequencing  

PubMed Central

Microbial activity in produced water from hydraulic fracturing operations can lead to undesired environmental impacts and increase gas production costs. However, the metabolic profile of these microbial communities is not well understood. Here, for the first time, we present results from a shotgun metagenome of microbial communities in both hydraulic fracturing source water and wastewater produced by hydraulic fracturing. Taxonomic analyses showed an increase in anaerobic/facultative anaerobic classes related to Clostridia, Gammaproteobacteria, Bacteroidia and Epsilonproteobacteria in produced water as compared to predominantly aerobic Alphaproteobacteria in the fracturing source water. The metabolic profile revealed a relative increase in genes responsible for carbohydrate metabolism, respiration, sporulation and dormancy, iron acquisition and metabolism, stress response and sulfur metabolism in the produced water samples. These results suggest that microbial communities in produced water have an increased genetic ability to handle stress, which has significant implications for produced water management, such as disinfection. PMID:25338024

Mohan, Arvind Murali; Bibby, Kyle J.; Lipus, Daniel; Hammack, Richard W.; Gregory, Kelvin B.

2014-01-01

394

A follow-up study on extracorporeal fixation of condylar fractures using vertical ramus osteotomy  

PubMed Central

Objectives The aim of this study is to report the results of extracorporeal fixation in patients with mandibular condylar fractures and compare them with the clinical results of conservative treatment. Materials and Methods The medical records of 92 patients (73 male [M] : 19 female [F], age 13-69 years, mean 33.1 years) treated for condylar fractures at the Department of Oral and Maxillofacial Surgery in Sun Dental Hospital (Daejeon, Korea) from 2007 to 2012 were reviewed. Patients were divided into three groups: group A (23 patients; M : F=18 : 5, age 21-69 years, mean 32.6 years), treated with extracorporeal fixation; group B (30 patients; M : F=24 : 6, age 16-57 years, mean 21.1 years), treated by conventional open reduction; and group C (39 patients; M : F=31 : 8, age 16-63 years, mean 34.4 years), treated with the conservative method ('closed' reduction). Clinical and radiographic findings were evaluated and analyzed statistically. Results Occurrence of postoperative condylar resorption correlated with certain locations and types of fracture. In this study, patients in group A (treated with extracorporeal fixation) did not demonstrate significant postoperative complications such as malocclusion, mandibular hypomobility, temporomandibular disorder, or complete resorption of condyle fragments. Conclusion In superiorly located mandibular condyle fractures, exact reconstruction of condylar structure with the conventional open reduction technique can be difficult due to the limited surgical and visual fields. In such cases, extracorporeal fixation of the condyle using vertical ramus osteotomy may be a better choice of treatment because it results in anatomically accurate reconstruction and low risk of complications. PMID:24868504

Park, Sung Yong; Im, Jae Hyoung; Yoon, Seong Hoe

2014-01-01

395

Scaling relations and spectral characteristics of tensile microseisms: evidence for opening/closing cracks during hydraulic fracturing  

NASA Astrophysics Data System (ADS)

Using formulae for both tensile and shear sources, we investigate spectral characteristics of microearthquakes induced by hydraulic fracturing, with application to passive-seismic data recorded during a multistage treatment programme in western Canada. For small moment magnitudes (Mw < 0), reliable determination of corner frequency requires accurate knowledge of QP and QS, although spectral estimates of magnitude are relatively unaffected by uncertainty in seismic attenuation. Here, we estimate QP and QS using spectral ratios derived from perforation shots. Of the microseismic events analysed during the hydraulic-fracture treatment, 17 of 20 exhibit an S/P spectral ratio <5, which is consistent with tensile failure. In addition, four microseismic events are characterized by a modulating source spectrum containing quasi-periodic notches. We interpret this spectral character to reflect a complex rupture pattern that involves rapid (5-8 ms) opening and closing of tensile cracks. In general, for tensile rupture on a penny-shaped crack, our model predicts that source radius (a) is related to moment magnitude (Mw) and internal fluid pressure within the fracture (Pi) by a simple empirical scaling relation: log10(a) = [9 - log102]/3 + 0.5Mw - log10(Pi)/3.

Eaton, David W.; van der Baan, Mirko; Birkelo, Brad; Tary, Jean-Baptiste

2014-03-01

396

Sensitivity of time lapse seismic data to the compliance of hydraulic fractures  

E-print Network

We study the sensitivity of seismic waves to changes in the fracture normal and tangential compliances by analyzing the fracture sensitivity wave equation, which is derived by differentiating the elastic wave equation with ...

Fang, Xinding

2013-01-01

397

Detection and quantification of rock physics properties for improved hydraulic fracturing in hydrocarbon-bearing shales.  

E-print Network

??Horizontal drilling and hydraulic stimulation make hydrocarbon production from organic-rich shales economically viable. Identification of suitable zones to drill a horizontal well and to initiate… (more)

Montaut, Antoine Marc Marie

2012-01-01

398

Vertical fracture of root filled teeth restored with posts: the effects of patient age and dentine thickness  

PubMed Central

Aim To determine whether patient age contributed to the fracture resistance of teeth subjected to root canal treatment and post placement. Methodology Forty-five single-rooted, single-canal human teeth were mounted, instrumented, obturated and prepared for a post. The teeth were divided into young (18 ? age ? 35) and old (60 ? age) groups and subjected to cyclic loading until fracture; those reaching 200 000 cycles without undergoing failure were then subjected to static loading to fracture. Statistical differences between groups were examined using one-way ANOVAS, and correlations were identified using Pearson’s r; significance was established at P ? 0.05. Results There was no significant difference between the two age groups in terms of the number of cycles to fracture (P > 0.05) or the load to fracture (P > 0.05). However, there was a significant correlation (P ? 0.05) between the root fracture resistance and individual age, indicating that the susceptibility to root fracture increases significantly with increasing patient age. Also, the dentine thickness of roots that fractured was significantly less than those that did not (P = 0.04). Conclusion Vertical root fracture of teeth receiving root canal treatment with posts is more likely to occur in the teeth of older patients (60+) and particularly in those with low dentine thickness. PMID:20158533

Mireku, A. S.; Romberg, E.; Fouad, A. F.; Arola, D.

2012-01-01

399

Determining sources of elevated salinity in pre-hydraulic fracturing water quality data using a multivariate discriminant analysis model  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing has the potential to introduce saline water into the environment due to migration of deep formation water to shallow aquifers and/or discharge of flowback water to the environment during transport and disposal. It is challenging to definitively identify whether elevated salinity is associated with hydraulic fracturing, in part, due to the real possibility of other anthropogenic sources of salinity in the human-impacted watersheds in which drilling is taking place and some formation water present naturally in shallow groundwater aquifers. We combined new and published chemistry data for private drinking water wells sampled across five southern New York (NY) counties overlying the Marcellus Shale (Broome, Chemung, Chenango, Steuben, and Tioga). Measurements include Cl, Na, Br, I, Ca, Mg, Ba, SO4, and Sr. We compared this baseline groundwater quality data in NY, now under a moratorium on hydraulic fracturing, with published chemistry data for 6 different potential sources of elevated salinity in shallow groundwater, including Appalachian Basin formation water, road salt runoff, septic effluent, landfill leachate, animal waste, and water softeners. A multivariate random number generator was used to create a synthetic, low salinity (< 20 mg/L Cl) groundwater data set (n=1000) based on the statistical properties of the observed low salinity groundwater. The synthetic, low salinity groundwater was then artificially mixed with variable proportions of different potential sources of salinity to explore chemical differences between groundwater impacted by formation water, road salt runoff, septic effluent, landfill leachate, animal waste, and water softeners. We then trained a multivariate, discriminant analysis model on the resulting data set to classify observed high salinity groundwater (> 20 mg/L Cl) as being affected by formation water, road salt, septic effluent, landfill leachate, animal waste, or water softeners. Single elements or pairs of elements (e.g. Cl and Br) were not effective at discriminating between sources of salinity, indicating multivariate methods are needed. The discriminant analysis model classified most accurately samples affected by formation water and landfill leachate, whereas those contaminated by road salt, animal waste, and water softeners were more likely to be discriminated as contaminated by a different source. Using this approach, no shallow groundwater samples from NY appear to be affected by formation water, suggesting the source of salinity pre-hydraulic fracturing is primarily a combination of road salt, septic effluent, landfill leachate, and animal waste.

Lautz, L. K.; Hoke, G. D.; Lu, Z.; Siegel, D. I.

2013-12-01

400

Use of arsenic and REE in black shales as potential environmental tracers in hydraulic fracturing operations  

NASA Astrophysics Data System (ADS)

Black shales commonly targeted for shale gas development were deposited under low oxygen concentrations, and typically contain high As levels. The depositional environment governs its solid-phase association in the sediment, which in turn will influence degree of remobilization during hydraulic fracturing. Organic carbon (OC), trace element (TE) and REE distributions have been used as tracers for assessing deep water redox conditions at the time of deposition in the Midcontinent Sea of North America (Algeo and Heckel, 2008), during large-scale oceanic anoxic events (e.g., Bunte, 2009) and in modern OC-rich sediments underlying coastal upwelling areas (e.g., Brumsack, 2006). We will present REE and As data from a collection of six different locations in the continental US (Kansas, Iowa, Oklahoma, Kentucky, North Dakota and Pennsylvania), ranging in age from Devonian to Upper Pennsylvanian, and from a Cretaceous black shale drilled on the Demerara Rise during ODP Leg 207. We interpret our data in light of the depositional framework previously developed for these locations based on OC and TE patterns, to document the mechanisms leading to REE and As accumulation, and explore their potential use as environmental proxies and their diagenetic remobilization during burial, as part of our future goal to develop a predictive evaluation of arsenic release from shales and transport with flowback waters. Total REE abundance (?REE) ranged from 35 to 420 ppm in an organic rich sample from Stark shale, KS. PAAS-normalized REE concentrations ranged from 0.5 to 7, with the highest enrichments observed in the MREE (Sm to Ho). Neither the ?REE nor the MREE enrichments correlated with OC concentrations or postulated depositional redox conditions, suggesting a principal association with aluminosilicates and selective REE fractionation during diagenesis. In the anoxic reducing environments in which black shales were deposited, sulfide minerals such as FeS2 trap aqueous arsenic in the crystal lattice, but As is also known to bind to the charged surfaces of clay minerals. Our arsenic concentration data show that the highest abundances (up to 70 ppm) are found in sediments with the highest total sulfur concentration (to 2.6 ppm), but there was no clear correlation with organic carbon or aluminosilicate content. We compare our results with preliminary data from a series of flowback waters sampled from ten producing wells in Pennsylvania and from high-pressure high-temperature experimental leaching of Marcellus shale samples.

Yang, J.; Torres, M. E.; Haley, B. A.; McKay, J. L.; Algeo, T. J.; Hakala, A.; Joseph, C.; Edenborn, H. M.

2013-12-01

401

Induced Seismicity in Northeast BC, Canada: Correlation With Operation Parameters of Shale Gas Hydraulic Fracturing  

NASA Astrophysics Data System (ADS)

The Horn River Basin and Montney Basin in northeast BC, Canada, are major shale-gas production areas in North America. The earthquake catalog compiled by the Geological Survey of Canada (GSC) using the Canadian National Seismograph Network (CNSN) data indicates that more than 40 earthquakes, with ML ranging between 2.2 and 3.6, occurred in the Horn River Basin since 2009 when the operation of hydraulic fracturing (HF) for shale gas development expanded significantly. In contrast, the GSC catalog shows no event for years before 2009, even though small-scale HF operations were performed as early as in 2007. In this study, we apply the single-station location and waveform correlation methods on continuous 3-component waveforms recorded at the only seismograph station in the region (Fort Nelson) to establish a comprehensive understanding of the spatiotemporal variation of the regional seismicity since 2002. We were able to locate 24 events during the one-year period between July 2002 and July 2003, with the largest ML being 2.9. This observation demonstrates that background seismicity in the Horn River Basin existed long before HF began. Since 2007, the occurrence of local earthquakes has become more frequent with gradually larger magnitude as the scale of HF in the region expands. An analysis of monthly HF operation parameters and local seismicity reveals a positive correlation between the total volume of injection and the maximum magnitude of local events. While the injection pressure during HF operations has been kept at a relatively constant level, the significant increase of injection volume in 2010 and 2011 coincides with a series of ML>3 events, with the largest being 3.6. The newly established state-of-the-art broadband seismograph stations in the region and the recent decline of HF operations in the Horn River Basin provide a rare opportunity to examine how the regional seismic pattern responds to different HF operation parameters, which in turn may give better insight into the physical mechanisms of induced seismicity.

Kao, H.; Farahbod, A.; Cassidy, J. F.; Walker, D. M.

2013-12-01

402

Bacterial communities associated with hydraulic fracturing fluids in thermogenic natural gas wells in North Central Texas, USA.  

PubMed

Hydraulic fracturing is used to increase the permeability of shale gas formations and involves pumping large volumes of fluids into these formations. A portion of the frac fluid remains in the formation after the fracturing process is complete, which could potentially contribute to deleterious microbially induced processes in natural gas wells. Here, we report on the geochemical and microbiological properties of frac and flowback waters from two newly drilled natural gas wells in the Barnett Shale in North Central Texas. Most probable number studies showed that biocide treatments did not kill all the bacteria in the fracturing fluids. Pyrosequencing-based 16S rRNA diversity analyses indicated that the microbial communities in the flowback waters were less diverse and completely distinct from the communities in frac waters. These differences in frac and flowback water communities appeared to reflect changes in the geochemistry of fracturing fluids that occurred during the frac process. The flowback communities also appeared well adapted to survive biocide treatments and the anoxic conditions and high temperatures encountered in the Barnett Shale. PMID:22066833

Struchtemeyer, Christopher G; Elshahed, Mostafa S

2012-07-01

403

Experimental evidence for hydrologic and mechanical controls on formation of hydraulic fractures in quartz-rich sandstone and siltstone  

NASA Astrophysics Data System (ADS)

Natural hydraulic fractures are inferred to form where pore fluid pressure exceeds the least compressive stress by an amount equal to the tensile strength of the rock (i.e. Pf-?3 ? T). However, consistent production of hydraulic fractures has not, until now, been possible. We report an experimental protocol which produces a pore fluid pressure gradient (?Pf) within a cylindrical sample, parallel to its long axis, such that Pf-?3 ? T is met within the sample. Two-dimensional poroelastic models of these experiments help interpret the timing and location of fracture formation in terms of the evolution and magnitudes of ?, ?, and Pf. The models are parametrized using the drained elastic properties (Poisson's ratio and bulk modulus) and hydrologic properties (permeability) of each sample. Four experiments on samples from the St. Peter Sandstone and two on samples from the Abo Formation were performed under these pore fluid pressure conditions as well as under drained conditions. None of the drained experiments resulted in sample failure, but all of the sandstone and one of the siltstone samples formed hydraulic fractures at elevated Pf. The St. Peter Sandstone samples are fine to medium-grained quartz arenites with spatially variable amounts of cement and primary structures. In the suite of samples studied, permeability ranges from k=10-12 m2 to k=10-15 m2. Two experiments were performed on a high-k sample with well defined cm-scale bedding, one with ?3 and ?Pf perpendicular to bedding and another with ?3 and ?Pf parallel to bedding. Two mechanically and hydrologically isotropic, low-k, samples were deformed. One is compositionally homogeneous and the other exhibits local iron oxide cements. The Abo Formation siltstone is a fluvial quartz-rich red bed with low permeability (k=10-17 m2) and mm-scale bedding laminae defined by grain shape preferred orientation and oxide and clay abundance. Experiments were performed with ?3 and ?Pf both perpendicular and parallel to bedding. The sample with ?3 parallel to bedding did not fail. Samples sustained conditions of Pf-?3 » T for up to 250sec prior to failure. Significant mechanical heterogeneity is a first order control on the fracture location, but is not required for fracture formation. The most isotropic and homogeneous sample failed after sustaining Pf-?3 > 10T for 30sec, with a through-going fracture that formed where Pf-?3 and ?, as determined from the poroelastic models, were greatest. The rest of the samples did not fail in locations of highest Pf-?3 and ?, but were localized along along mechanical heterogeneities. However, these samples still fractured where Pf-?3 » T prior to failure. Typical Mohr-Coulomb and Griffith failure criteria do not explain the large stresses sustained prior to failure. Interestingly, samples did experience similar total strain at failure regardless of differences in mechanical properties and experimental conditions. Our results suggest that in a space-limited system, fracture formation is dependent on the ability of the system to accommodate sufficient strain.

French, M. E.; Goodwin, L. B.; Boutt, D. F.

2009-12-01

404

The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale  

E-print Network

without silicone-base sealant ...................... 22 Figure 10 - Aluminum mold used for coating samples in silicone-base sealant .............. 24 Figure 11 - Aluminum mold inner surface...-base sealant (epoxy). An alumninum mold toleranced, to coat a sample in epoxy while still maintaining the ability to slide into the modified API cell, is used to coat the sample in the epoxy. Step by step procedure for coating a sample in epoxy is outlined...

Briggs, Kathryn

2014-05-05

405

Alteration of the Hydraulic and Seismic Properties of a Fracture by Mineral Precipitation and Sand Deposition  

NASA Astrophysics Data System (ADS)

In the near subsurface, rocks are exposed to multiple natural and human made processes that can alter the properties of the rock. These processes can be chemical dissolution, mineral precipitation as well as sand deposition and transport. All these processes alter the hydrological and seismic properties of fractured rock. In this study we used a fractured carbonate rock (150 mm of diameter and 75 mm of height) to study the effect of mineral precipitation and fine sand deposition on the hydrological and seismic properties of the fracture. Prior to geochemical and transport alteration of the fracture, surface roughness measurements were made using laser profilometry to quantify the fracture void geometry. Reconstruction of the fracture void geometry showed quasi-linear channels through the fracture with a correlation length of 20 mm. The long linear channels were not observed in the seismic data for the fracture when it was initially saturated with water. For seismic measurements, water usually masks heterogeneity in a fracture. However, the flow measurements made from eight ports around the sample did indicate flow anisotropy. Next, the fracture void geometry was altered using a solution of hydrochloric acid and sulfuric acid to alternately etch the fracture and precipitate gypsum in the fracture. This reactive solution resulted in an increase in flow rate for several ports but not all. The seismic data showed that portions of the fracture exhibited enhanced transmission, while other portions exhibited a decrease in transmission. Finally, fine sand transport and deposition were performed by using an aqueous containing solid spherical silica beads (an average radius of 25 micrometers). While the flow rate remained relatively constant in three out of four ports, the seismic transmission across the fracture increased. In addition, the structure of the void geometry became apparent in the seismic data. We hypothesize that the deposition of the fine sand was controlled by the fracture flow path geometry and preferentially deposited along regions of contacts or small apertures. In this experiment, the aqueous sand solution had a concentration of 0.23 g per 100 ml. For this concentration, the fine sand provided additional coupling between the fracture surfaces thereby enhancing seismic wave propagation but did not significantly affecting the flow properties of the fracture. Acknowledgments: LJPN wishes to acknowledge the Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy DE-FG02-97ER14785 08 for support of this research.

Acosta-Colon, A. A.; Pyrak-Nolte, L. J.

2006-12-01

406

Fracture hydraulic conductivity in the Mexico City clayey aquitard: Field piezometer rising-head tests  

NASA Astrophysics Data System (ADS)

A regional lacustrine aquitard covers the main aquifer of the metropolitan area of Mexico City. The aquitard's hydraulic conductivity (K') is fundamental for evaluating the natural protection of the aquifer against a variety of contaminants present on the surface and its hydraulic response. This study analyzes the distribution and variation of K' in the plains of Chalco, Texcoco and Mexico City (three of the six former lakes that existed in the Basin of Mexico), on the basis of 225 field-permeability tests, in nests of existing piezometers located at depths of 2-85 m. Tests were interpreted using the Hvorslev method and some by the Bouwer-Rice method. Results indicate that the distribution of K' fits log-Gaussian regression models. Dominant frequencies for K' in the Chalco and Texcoco plains range between 1E-09 and 1E-08 m/s, with similar population means of 1.19E-09 and 1.7E-09 m/s, respectively, which are one to two orders of magnitude higher than the matrix conductivity. In the Mexico City Plain the population mean is near by one order of magnitude lower; K'=2.6E-10 m/s. The contrast between the measured K' and that of the matrix is attributed to the presence of fractures in the upper 25-40 m, which is consistent with the findings of previous studies on solute migration in the aquitard. Un imperméable régional d'origine lacustre recouvre le principal aquifère de la zone urbaine de la ville de Mexico. La conductivité hydraulique K' de cet imperméable est fondamentale pour évaluer la protection naturelle de l'aquifère, contre les différents contaminants présents en surface, et sa réponse hydraulique. Cette étude analyse et les variations de K' dans les plaines de Chalco, Texcoco et Mexico (trois des six anciens lacs qui existaient dans le Bassin de Mexico), sur la base de 225 essais de perméabilité sur le terrain, réalisés en grappes dans des piézomètres existants entre 2 et 85 m de profondeur. Les essais ont été interprétés avec la méthode de Hvorslev et certains avec la méthode de Bouwer-Rice. Les résultats indiquent que la distribution de K' s'ajuste à des modèles de régression log-gaussiens. Les valeurs de K' les plus fréquentes dans les plaines de Chalco et de Texcoco sont entre 1E-09 et 1E-08 m/s, avec des moyennes similaires de 1.19E-09 et 1.7E-09 m/s respectivement, qui sont d'un ou deux ordres de grandeurs supérieures à la conductivité de la matrice. Dans la plaine de Mexico, la moyenne est proche d'un ordre de grandeur en moins, avec 2.6E-10 m/s. Ce contraste entre le K' mesuré et celui de la matrice est attribué à la présence de fractures dans les 25-40 m supérieurs, ce qui est en accord avec les études précédentes sur la migration de solutés au travers de l'imperméable. El acuífero principal del Área Metropolitana de la Ciudad de México está recubierto por un acuitardo regional lacustre, cuya conductividad hidráulica es fundamental para evaluar la protección natural de las aguas subterráneas contra los contaminantes presentes en superficie y su respuesta hidráulica. Este estudio analiza la distribución y variación de dicha conductividad en las llanuras de Chalco, Texcoco y Ciudad de México (tres de los seis lagos que existían al principio en la Cuenca de México) a partir de 225 ensayos de campo en piezómetros múltiples existentes, ubicados entre 2 y 85 m de profundidad. La interpretación de los ensayos se ha realizado mediante el método de Hvorslev y-algunos-el de Bouwer-Rice. Los resultados indican que la distribución de la conductividad se ajusta a modelos de regresión lognormales. Las frecuencias dominantes en las Llanuras de Chalco y Texoco están comprendidas entre 1-9 y 10-8 m/s, con medias de población similares de 1.19×10-9 y 1.70×10-9 m/s, respectivamente, que son dos órdenes de magnitud mayores que el valor de la matriz. En el Llano de México, la media es casi un orden de magnitud inferior (2.60×10-10 m/s). Se atribuye este contraste entre la conductividad hidráulica medida y la de la matriz a la presencia de fracturas en el tramo s

Vargas, Carlos; Ortega-Guerrero, Adrián

407

Three-Dimensional Hydraulic Fracture Propagation in the Presence of Stress Variations  

Microsoft Academic Search

Models of three-dimensional (3D) fracture propagation are being developed to study the effect of variations of stress and rock properties on fracture height and bottomhole pressure (BHP). Initially a blanket sand bounded by zones of higher minimum in-situ stress is considered, with stresses symmetrical about both the payzone axis and the wellbore. An elliptical fracture perimeter is assumed. Fluid flows

Ian Palmer

1983-01-01

408

Numerical analysis of hydraulic characteristics of fracture intersected with karst conduit based on navier-stokes equation  

NASA Astrophysics Data System (ADS)

The flow in karstic geometry is an important problem in groundwater researches and engineering applications. However, the mechanism controlling the flow status in these areas is still not clear. In this study, we investigated the hydraulic characteristics with numerical models considering a single fracture intersected with a karst conduit. The numerical model used here is a FVM model based on Navier-Stokes equation which was successfully verified with the test result taken from literature. Five factors and four levels were considered in this study, including the length of the karst conduit, aperture of the fracture, diameter of the conduit, hydraulic condition and the cross angle and sixteen cases were designed according to orthogonal design. A non-dimensional number ? (the ratio of the fracture aperture to diameter of the conduit) was defined in analysis of the combined effect of the two factors on flow characters. The most important impacting factors and the stability levels were obtained in order to improve the accuracy of the results in numerical simulations. A mathematical model was built for the relationship between discharge of the conduit and the impacting factors with consideration of the combined effects based on dimension analysis and changeable structure genetic algorithm. The converting permeability coefficient was estimated in order to solve the stream wise head loss considering the combined effects of the flow in karst conduit and fractures with Darcy's law. The results show that the most important impacting factor for flux might be the fracture aperture or the diameter of the conduit which is determined by the non-dimensional number ?. The conduit has more influence on the whole pressure field with larger diameter and smaller length. The head loss has a non-linear relationship with the velocity because of the local head loss near the karst conduit. Thus, the local cubic's law is no longer applicable to characterize the flow in the fracture near the conduit. In this situation, the flow can be simulated by the general Darcy's law form with the converting permeability coefficient.

Tao, X.; Zhao, J.; Zhao, Z.; Li, Y.; Qiu, L.

2013-12-01

409

Contrasting groundwater quality in areas with and without gas production by hydraulic fracturing near the PA/NY border  

NASA Astrophysics Data System (ADS)

Shale gas development, including drilling and hydraulic fracturing, is rapidly increasing throughout the United States and, indeed, the rest of the world. Systematic surveys of water quality both pre- and post drilling/production are sparse. To examine the impacts of shale gas production on water quality, pilot studies are being conducted in adjacent counties of western NY (Chemung, Tioga, Broome, and Delaware) and northern PA (Bradford, Susquehanna, and Tioga). These 7 counties along the border of NY and PA share similar geology and demographic compositions and have been identified as a key area to develop shale gas with the key difference that active fracking is occurring in PA but there is no fracking yet in NY due to the current moratorium in that state. Measurements include a suite of volatile organic compounds (VOCs), major and trace elements, methane and its stable isotopes, noble gases and tritium for dating purposes, and the primary radioactive elements of potential concern, radon and radium. We found elevated methane levels on both sides of the border, and some wells show elemental fingerprints characteristic for shale fluids. Field observations at several wells near drill sites in PA suggested elevated levels of organics, possibly from hydraulic fracturing activities. The full suite of lab analyses is currently ongoing and can be used to further characterize sources of these organics.

Stute, M.; Yan, B.; Ross, J. M.; Chillrud, S. N.; Saberi, P.; Panettieri, R. A.

2013-12-01

410

Vertical distribution of soil saturated hydraulic conductivity and its influencing factors in a small karst catchment in Southwest China.  

PubMed

Saturated hydraulic conductivity (Ks) is one of the most important soil hydraulic parameters influencing hydrological processes. This paper aims to investigate the vertical distribution of Ks and to analyze its influencing factors in a small karst catchment in Southwest China. Ks was measured in 23 soil profiles for six soil horizons using a constant head method. These profiles were chosen in different topographical locations (upslope, downslope, and depression) and different land-use types (forestland, shrubland, shrub-grassland, and farmland). The influencing factors of Ks, including rock fragment content (RC), bulk density (BD), capillary porosity (CP), non-capillary porosity (NCP), and soil organic carbon (SOC), were analyzed by partial correlation analysis. The mean Ks value was higher in the entire profile in the upslope and downslope, but lower value, acting as a water-resisting layer, was found in the 10-20 cm soil depth in the depression. Higher mean Ks values were found in the soil profiles in the forestland, shrubland, and shrub-grassland, but lower in the farmland. These results indicated that saturation-excess runoff could occur primarily in the hillslopes but infiltration-excess runoff in the depression. Compared with other land-use types, surface runoff is more likely to occur in the farmlands. RC had higher correlation coefficients with Ks in all categories concerned except in the forestland and farmland with little or no rock fragments, indicating that RC was the dominant influencing factor of Ks. These results suggested that the vertical distributions of Ks and RC should be considered for hydrological modeling in karst areas. PMID:25663401

Fu, Tonggang; Chen, Hongsong; Zhang, Wei; Nie, Yunpeng; Wang, Kelin

2015-03-01

411

Hydraulic Fracture Optimization with a Pseudo-3D Model in Multi-layered Lithology  

E-print Network

based on the so-called two-dimensional models (2D) focus on the optimization of fracture length and width, assuming one can estimate a value for fracture height, while so-called pseudo three dimensional (p-3D) models suitable for multi-layered reservoirs...

Yang, Mei

2011-10-21

412

INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS  

Microsoft Academic Search

The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient COâ flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, we divided the report into two chapters. The first chapter was to image

David S. Schechter

2005-01-01

413

Foulger, G.R., B.R. Julian and F.C. Monastero, Microearthquake characterisation of an artificially stimulated hydraulic fracture at the Coso geothermal area, California, EOS Trans. AGU, Fall Meet. Suppl., Abstract, 2006.  

E-print Network

stimulated hydraulic fracture at the Coso geothermal area, California, EOS Trans. AGU, Fall Meet. Suppl., Abstract, 2006. Microearthquake characterisation of an artificially stimulated hydraulic fracture geothermal area. This well was re-drilled February ­ March 2005 with the intention of hydrofracturing

Foulger, G. R.

414

Water quality impacts of hydraulic-fracturing chemicals observed in a permeable, quartz-sand aquifer  

NASA Astrophysics Data System (ADS)

A pilot scale experiment was conducted on western Cape Cod, Massachusetts to test the use of hydraulic fracturing (HF) for emplacing permeable reactive barriers (PRB) where the water table is too far below land surface to use standard excavation methods. Two PRB were emplaced 24 to 36 meters below land surface in a plume with low concentrations of perchloroethylene in oxic, mildly acidic groundwater with low concentrations of dissolved salts. The granular aquifer sediments consist of permeable sands and gravels. Quartz comprises greater than 90% by weight of the aquifer sediments but chemical reactivity of the sediments is controlled by micrometer-scale chlorite and illite and nanometer-scale aluminum-substituted goethite. HF fluids contained guar gum (gelling agent), cellulose enzyme and acetic acid (breakers), sodium borate (cross-linker), potassium (K) carbonate (pH adjustor), and sodium (Na) chloride (tracer). Water-quality impacts within about 20 meters of the PRB were monitored over a 1.7-year period following HF. Arrival of HF-chemicals was marked by an increase in boron (B) from ambient concentrations of 6 uM to >800 uM. B concentrations rose for approximately 50 days, much longer than the 22-day period over which HF was conducted. B concentrations subsequently decreased but remained 2-3 times above background concentrations for almost one year. Elevated Na and K concentrations in the HF fluids drove sorption (including ion exchange) reactions resulting in transient increases in naturally occurring major, minor, and trace cations up to 20 to 50 times background concentrations. Increases in dissolved organic carbon (DOC) and decreases in dissolved oxygen (DO) concentrations were observed as B concentrations increased. DOC concentration subsequently decreased but remained significantly above background. DO concentrations remained below detection. Dissolved iron (Fe) and manganese (Mn) concentrations increased as DO concentrations decreased below detection and remained elevated 1.7 years after HF. Reactions with Fe in the PRB may have contributed to the observed Fe concentrations but Mn was likely released from the aquifer sediments. Fe and Mn concentrations remained elevated throughout the sampling period. Dissolved arsenic concentrations increased after anaerobic conditions were established from below detection to 0.3-0.5 uM. HF fluids contained only a subset of the chemicals used in typical HF stimulations and aquifer sediments were likely less reactive than aquifer solids at other sites. Despite these differences, several findings have applicability to other sites. B is a potentially useful tracer of intrusion of HF fluids into aquifers, but elevated concentrations may be short-lived. Sorption reactions driven by differences in dissolved salt concentrations between HF fluids and ambient groundwater result in changes in cation concentrations, including barium and strontium. Organic compounds in HF fluids may drive aerobic aquifers anaerobic. Anaerobic conditions may lead to mobilization of naturally occurring contaminants like arsenic, whose reduced forms are more mobile than oxidized forms.

Kent, D. B.; LeBlanc, D. R.; Smith, R. L.

2012-12-01

415

Microseismic monitoring of the hydraulic-fracture growth and geometry in the Upper Bahariya member, Khalda concession, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Three-component, downhole geophones are installed in production wells at the Khalda and Kahraman sites to monitor hydraulic fracturing treatment in a nearby well. Locatable microseismic events were distributed in space around the treatment well using the hypocenter-velocity inversion method. The E-W oriented microseismic pattern aligns with the proposed specifications of fracture model design at both the Khalda and Kahraman sites. Due to the small magnitude and long separation distance between the treatment well and the recording string, microseismicity was dominantly observed during the main fracturing operation at both the Khalda and Kahraman sites, with calculated magnitudes less than -0.3?Mw. In addition, the calculated confidence for locatable events was generally average or low. The seismic zone through the mainfrac treatment was estimated to spread over 58?m height and 320?m length at the Khalda site, while the zone of the Kahraman site was enclosed within 25?m height and 250?m length. The stimulated reservoir volume (SRV) at the Khalda site was estimated to be 433?200?m3, with asymmetrical wings around the stimulation well, but at the Kahraman site the stimulation imaging was marginally successful and the stimulated SRV was only 247?000?m3. In general, the two microseismic experiments at Khalda and Kahraman were relatively successful in locating the microseismic events and calculating the SRV within the producing horizon, elucidating the importance of the microseismic technique in monitoring reservoir stimulation.

Abdulaziz, Abdulaziz M.

2014-08-01

416

Hydraulic and mechanical properties of natural fractures in low-permeability rock  

SciTech Connect

The results of a comprehensive laboratory study of the mechanical displacement, permeability, and void geometry of single rock fractures in a quartz monzonite are summarized and analyzed. A metal-injection technique was developed that provided quantitative data on the precise geometry of the void spaces between the fracture surfaces and the areas of contact at different stresses. At effective stresses of less than 20 MPa fluid flow was proportional to the mean fracture aperture raised to a power greater than 3. As stress was increased, contact area was increased and void spaces become interconnected by small tortuous channels that constitute the principal impediment to fluid flow. At effective stresses higher than 20 MPa, the mean fracture aperture continued to diminish with increasing stress, but this had little effect on flow because the small tortuous flow channels deformed little with increasing stress.

Pyrack-Nolte, L.J.; Myer, L.R.; Cook, N.G.W.; Witherspoon, P.A.

1987-01-01

417

Evidence of Reopened Microfractures in Production Data of Hydraulically Fractured Shale Gas Wells  

E-print Network

the presence of reopened natural fracture network can be observed in pressure and production data of shale gas wells producing from two shale formations with different well and reservoir properties. Homogeneous, dual porosity and triple porosity models...

Apiwathanasorn, Sippakorn

2012-10-19

418

Stochastic Programming Approach to Hydraulic Fracture Design for the Lower Tertiary Gulf of Mexico  

E-print Network

.......................................................................................... 1 Deep-water Lower Tertiary Background ............................................. 3 Research Objectives ............................................................................. 7 Literature Review... ....................................... 47 Finite Conductivity Fracture Approximation ..................................... 52 Proppant Allocation in Multilayer Reservoirs .................................... 53 vi IV STOCHASTIC OPTIMIZATION...

Podhoretz, Seth

2013-07-27

419

INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS  

SciTech Connect

The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. This report provides results of the second semi-annual technical progress report that consists of three different topics. In the first topic, laboratory experiments were performed on a Berea core to investigate the changes in rock properties and fluid flow under different stress-state conditions. A comparative study of different stress conditions was also conducted to analyze the effect of the various loading systems. The experimental results show that fracture permeability reduces significantly as the stress increases compared to matrix permeability. The hydrostatic and triaxial stresses have greater impacts on permeability reduction compared to applying stress in the uniaxial stress condition. Fracture flow dominates when the applied stress is less, however, the matrix flow rate increases as applied stress increases and dominates at high stress even if the fracture does not heal completely. In the second topic, the preliminary results of static imbibition experiments are presented as a precursor to image the saturation profiles using X-Ray CT scanner. The static and dynamic imbibition experiments have been done previously (Schechter et al, 2002). The imaging of imbibition experiment is underway to track the saturation profiles using X-ray CT scanner. Hence, no more conclusions are drawn from this study at this time. In the last topic, the modeling of fluid flow through a single fracture incorporating the effect of surface roughness is conducted. Fracture permeability is usually estimated by a cubic law that is based on the theory of hydrodynamics for the laminar flow between flat plates. However, the cubic law is too simple to estimate the fracture permeability correctly, because the surface of real fracture is much more complicated and rougher than the surface of flat plate. Several researchers have shown that the flow characteristics of an actual fracture surface would be quite different due to the effect of tortuosity, impact of surface roughness and contact areas. Nonetheless, to date, these efforts have not converged to form a unified definition on the fracture aperture needed in the cubic law. In this study, therefore, we show that the cubic law could still be used to model small-scale and field-scale data as long as it is modeled effectively, accounting for the effect of surface roughness associated with the fracture surface. The goal of this research is to examine the effect of surface roughness for flow through fractures and to effectively incorporate them into simulations with the aid of geostatistics. Since the research has been supported with experimental results, the consistency of the results enabled us to define a methodology for single fracture simulation. This methodology successfully modeled the slow rate and pressure drop from fractured core experiments, which were earlier not possible through parallel plate approach. Observations suggest that the fracture aperture needs to be distributed to accurately model the experimental results. The effect of friction and tortuosity due to surface roughness needs to be taken into account while modeling.

David S. Schechter

2002-10-30

420

Investigation of Efficiency Improvements During CO2 Injection in Hydraulically and Naturally Fractured Reservoirs  

SciTech Connect

The objective of this project was to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO2 flooding in heterogeneous or fracture-dominated reservoirs. This report provided results of the second semi-annual technical progress report that consists of three different topics.

Schechter, David S.; Vance, Harold

2003-03-10

421

Estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses  

SciTech Connect

The flow parameters of a natural fracture were estimated by modeling in situ pressure pulses. The pulses were generated in two horizontal boreholes spaced 1 m apart vertically and intersecting a near-vertical highly permeable fracture located within a shallow fractured carbonate reservoir. Fracture hydromechanical response was monitored using specialized fiber-optic borehole equipment that could simultaneously measure fluid pressure and fracture displacements. Measurements indicated a significant time lag between the pressure peak at the injection point and the one at the second measuring point, located 1 m away. The pressure pulse dilated and contracted the fracture. Field data were analyzed through hydraulic and coupled hydromechanical simulations using different governing flow laws. In matching the time lag between the pressure peaks at the two measuring points, our hydraulic models indicated that (1) flow was channeled in the fracture, (2) the hydraulic conductivity tensor was highly anisotropic, and (3) the radius of pulse influence was asymmetric, in that the pulse travelled faster vertically than horizontally. Moreover, our parametric study demonstrated that the fluid pressure diffusion through the fracture was quite sensitive to the spacing and orientation of channels, hydraulic aperture, storativity and hydraulic conductivity. Comparison between hydraulic and hydromechanical models showed that the deformation significantly affected fracture permeability and storativity, and consequently, the fluid pressure propagation, suggesting that the simultaneous measurements of pressure and mechanical displacement signals could substantially improve the interpretation of pulse tests during reservoir characterization.

Cappa, F.; Guglielmi, Y.; Rutqvist, J.; Tsang, C.-F.; Thoraval, A.

2008-03-16

422

INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS  

SciTech Connect

The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, we divided the report into two chapters. The first chapter was to image and perform experimental investigation of transfer mechanisms during CO{sub 2} flooding in NFR and HFR using X-ray CT scanner. In this chapter, we emphasized our work on understanding the connection between fracture properties and fundamentals of transfer mechanism from matrix to fractures and fluid flow through fracture systems. We started our work by investigating the effect of different overburden pressures and stress-state conditions on rock properties and fluid flow. Since the fracture aperture is one of important parameter that governs the fluid flow through the fracture systems, the average fracture aperture from the fluid flow experiments and fracture aperture distribution derived from X-ray CT scan were estimated for our modeling purposes. The fracture properties and fluid flow have significant changes in response to different overburden pressures and stress-state conditions. The fracture aperture distribution follows lognormal distribution even at elevated stress conditions. Later, we also investigated the fluid transfers between matrix and fracture that control imbibition process. We evaluated dimensionless time for validating the scheme of upscaling laboratory experiments to field dimensions. In CO{sub 2} injection experiments, the use of X-ray CT has allowed us to understand the mechanisms of CO{sub 2} flooding process in fractured system and to take important steps in reducing oil bypassed. When CO{sub 2} flooding experiments were performed on a short core with a fracture at the center of the core, the gravity plays an important role in the recovery of oil even in a short matrix block. This results are contrary with the previous believes that gravity drainage has always been associated with tall matrix blocks. In order to reduce oil bypassed, we injected water that has been viscosified with a polymer into the fracture to divert CO{sub 2} flow into matrix and delay CO{sub 2} breakthrough. Although the breakthrough time reduced considerably, water ''leak off'' into the matrix was very high. A cross-linked gel was used in the fracture to avoid this problem. The gel was found to overcome ''leak off'' problems and effectively divert CO{sub 2} flow into the matrix. As part of our technology transfer activity, we investigated the natural fracture aperture distribution of Tensleep formation cores. We found that the measured apertures distributions follow log normal distribution as expected. The second chapter deals with analysis and modeling the laboratory experiments and fluid flow through fractured networks. We derived a new equation to determine the average fracture aperture and the amount of each flow through fracture and matrix system. The results of this study were used as the observed data and for validating the simulation model. The idea behind this study is to validate the use of a set of smooth parallel plates that is common in modeling fracture system. The results suggest that fracture apertures need to be distributed to accurately model the experimental results. In order to study the imbibition process in details, we developed imbibition simulator. We validated our model with X-ray CT experimental data from different imbibition experiments. We found that the proper simulation model requires matching both weight gain and CT water saturation simultaneously as oppose to common practices in matching imbibition process with weight gain only because of lack information from CT scan. The work was continued by developing dual porosity simulation using empirical transfer function (ETF) derived from imbibition experiments. This allows reduction of uncertainty parameter in modeling transfer of fluids from matrix to the fra

David S. Schechter

2005-09-28

423

Overview of EPA's Approach to Developing Prospective Case Studies Technical Workshop: Case Studies to Assess Potential Impacts of Hydraulic Fracturing on Drinking Water Resources  

EPA Science Inventory

One component of the United States Environmental Protection Agency's (EPA) study of the potential impacts of hydraulic fracturing on drinking water resources is prospective case studies, which are being conducted to more fully understand and assess if and how site specific hydrau...

424

UK Oil and Gas Collaborative Doctoral Training Centre (2014 start) Project Title: Coupled flow of water and gas during hydraulic fracture in shale (EARTH-15-CM1)  

E-print Network

of water and gas during hydraulic fracture in shale (EARTH-15-CM1) Host institution: University of Oxford Cartwright Project description: Recovery of natural gas from mudstone (shale) formations has triggeredUK Oil and Gas Collaborative Doctoral Training Centre (2014 start) Project Title: Coupled flow

Henderson, Gideon

425

Data regarding hydraulic fracturing distributions and treatment fluids, additives, proppants, and water volumes applied to wells drilled in the United States from 1947 through 2010  

USGS Publications Warehouse

Comprehensive, published, and publicly available data regarding the extent, location, and character of hydraulic fracturing in the United States are scarce. The objective of this data series is to publish data related to hydraulic fracturing in the public domain. The spreadsheets released with this data series contain derivative datasets aggregated temporally and spatially from the commercial and proprietary IHS database of U.S. oil and gas production and well data (IHS Energy, 2011). These datasets, served in 21 spreadsheets in Microsoft Excel (.xlsx) format, outline the geographical distributions of hydraulic fracturing treatments and associated wells (including well drill-hole directions) as well as water volumes, proppants, treatment fluids, and additives used in hydraulic fracturing treatments in the United States from 1947 through 2010. This report also describes the data—extraction/aggregation processing steps, field names and descriptions, field types and sources. An associated scientific investigation report (Gallegos and Varela, 2014) provides a detailed analysis of the data presented in this data series and comparisons of the data and trends to the literature.

Gallegos, Tanya J.; Varela, Brian

2015-01-01

426

Hydraulic-fracturing measurmements in two boreholes near the Spent Fuel Test-Climax, Climax Stock, Nevada Test Site  

USGS Publications Warehouse

Hydraulic-fracturing measurements are used to infer the magnitude of the least principal stress in the vicinity of the Spent Fuel Test-Climax, located in the Climax stock at the Nevada Test Site. The measurements, made at various depths in two exploratory boreholes, suggest that the local stress field is not uniform. Estimates of the least principal stress magnitude vary over distances of a few tens of meters, with the smaller values averaging 2.9 MPa and the larger values averaging 5.5 MPa. The smaller values are in agreement with the minimum-stress magnitude of 2.8 MPa determined in a nearby drift in 1979, using an overcoring technique. Jointing in the granitic rock mass and (or) the influence of nearby faults may account for the apparent variation in minimum-stress magnitude indicated by the hydrofracture data.

Ellis, William L.

1983-01-01