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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

Creation of multiple sequential hydraulic fractures via hydraulic fracturing combined with controlled pulse fracturing  

Microsoft Academic Search

A method for creating multiple sequential hydraulic fractures via hydraulic fracturing combined with controlled pulse fracturing is described comprising: (a) creating more than two simultaneous multiple vertical radial fractures via a controlled pulse fracturing method; (b) applying thereafter hydraulic pressure to the formation in an amount sufficient to fracture; (c) maintaining the hydraulic pressure on the formation while pumping alternate

Uhri

1988-01-01

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

Hydraulic fracturing  

Microsoft Academic Search

A method is described of fracturing a subterranean formation which contains at least 2 fluids of different densities, which are located in superimposed strata substantially in accordance with their densities. At least 2 piping systems or injection means are employed which provide independent injection of different fluids simultaneously down the wellbore. Down one of these means a fluid is injected

Prater

1968-01-01

5

Hydraulic fracturing process  

Microsoft Academic Search

A process is described for hydraulically fracturing a permeable subterranean formation in which the fracture faces are treated to reduce their permeability to the fracturing fluid. Propping agent is placed in the fracture in a conventional manner whereby the bulk of the propping agent is deposited in the fracture at a location remote from the well. Thereafter the fracture faces

Pye

1973-01-01

6

Hydraulic fracture design optimization  

SciTech Connect

This research and development investigation, sponsored by US DOE and the oil and gas industry, extends previously developed hydraulic fracture geometry models and applied energy related characteristic time concepts towards the optimal design and control of hydraulic fracture geometries. The primary objective of this program is to develop rational criteria, by examining the associated energy rate components during the hydraulic fracture evolution, for the formulation of stimulation treatment design along with real-time fracture configuration interpretation and control.

Lee, Tae-Soo; Advani, S.H.

1992-01-01

7

Hydraulic fracture design optimization  

SciTech Connect

This research and development investigation, sponsored by US DOE and the oil and gas industry, extends previously developed hydraulic fracture geometry models and applied energy related characteristic time concepts towards the optimal design and control of hydraulic fracture geometries. The primary objective of this program is to develop rational criteria, by examining the associated energy rate components during the hydraulic fracture evolution, for the formulation of stimulation treatment design along with real-time fracture configuration interpretation and control.

Lee, Tae-Soo; Advani, S.H.

1992-06-01

8

Sequential hydraulic fracturing of a subsurface formation  

Microsoft Academic Search

This patent describes a method for propagating a vertical hydraulic fracture in an earth formation surrounding a borehole wherein the original in-situ stresses favor a horizontal fracture. It comprises: pumping a first fracturing fluid into the formation at a first depth within the borehole so that a first fracturing pressure is applied to the formation by the first fracturing fluid

T. C. Jr. Vogt; M. W. Hale; J. R. Sellers

1989-01-01

9

Hydraulic fracture analysis method  

SciTech Connect

A method of determining the orientation of a hydraulic fracture plane in the earth is described, consisting of: positioning an array of sensors for measuring seismic ground motion above a region which includes the fracture, providing a well bore having fluid therein communicating with the fracture to be defined, perturbing the fluid to cause transient pressure or flow oscillations in the fluid column in the well bore, measuring seismic ground motion induced by the transient pressure and flow oscillations in the fracture, calculating, using theory of wave propagation, the ground motion expected of fractures of different orientations, comparing the measured ground motion with the calculated ground motion patterns representing fractures of different orientations, selecting the fracture orientation that yields calculated seismic ground motions most closely resembling the measured seismic ground motions as the most probable fracture orientation, and calculating a probable fracture orientation based on the seismic motion of the ground.

Holzhausen, G.R.; St. Lawrence, W.

1989-01-31

10

Hydraulic fracturing technique  

Microsoft Academic Search

This improved hydraulic fracturing method consists of injecting into previously formed fractures filled with a very viscous fluid, a relatively nonviscous fluid containing sand or other propping agent material. The low viscosity fluid fingers through the high viscosity fluid in radial channels and when the fingers containing the propping agent reach the extremity of the highly viscous fluid, they mushroom

1965-01-01

11

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

12

Stress Determination by Hydraulic Fracturing in Subsurface Waste Injection  

Microsoft Academic Search

By the utilization of commercially available and specially designed equipment, hydraulic fracturing experiments were conducted on a regional scale in the Piceance Basin of northwest Colorado. These tests confirmed that vertical fractures may be hydraulically induced at well-face injection pressure of about two thirds of the total overburden load. Further, the fractures will continue to propagate vertically as long as

R. G. Wolff; J. D. Bredehoeft; W. S. Keys; Eugene Shuter

1975-01-01

13

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

14

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

15

Hydraulic fracturing propping agent  

SciTech Connect

A high strength propping agent for use in hydraulic fracturing of subterranean formations comprising solid, spherical particles having an alumina content of between 40 and 60%, a density of less than 3.0 gm/cc and an ambient temperature permeability of 100,000 or more millidarcies at 10,000 psi.

Lunghofer, E. P.

1985-06-11

16

Hydraulic fracturing propping agent  

Microsoft Academic Search

A high strength propping agent for use in hydraulic fracturing of subterranean formations comprising solid, spherical particles having an alumina content of between 40 and 60%, a density of less than 3.0 gm\\/cc and an ambient temperature permeability of 100,000 or more millidarcies at 10,000 psi.

Lunghofer

1985-01-01

17

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

18

Hydraulic Fracture Containment in Sand  

Microsoft Academic Search

The mechanism of hydraulic fracturing in soft, high permeability material is considered fundamentally different from that in hard, low permeability rock, where a tensile fracture is created and conventional linear elastic fracture mechanics (LEFM) applies. The fracturing and associated modeling work is then a relatively new area. Particularly, the fracture containment in layered formations remains unknown. This research is aiming

Y. Dong

2010-01-01

19

The Effective Fracture Toughness in Hydraulic Fracturing  

Microsoft Academic Search

This paper examines the effective fracture toughness approach which is used in hydraulic fracturing in order to explain the\\u000a high net-pressures that are often observed in field operations. The effective fracture toughness is calculated using a fully\\u000a deterministic elasto-plastic hydraulic fracturing model. Rock is modelled by Mohr–Coulomb flow theory of plasticity for cohesive-frictional\\u000a dilatant material. Fluid flow is modelled by

Panos Papanastasiou

1999-01-01

20

Influence of natural fractures on hydraulic fracture propagation  

SciTech Connect

Hydraulic fracturing has become a valuable technique for the stimulation of oil, gas, and geothermal reservoirs in a variety of reservoir rocks. In many applications, only short fractures are needed for economic production. In low-permeability reservoirs, however, long penetrating fractures are generally needed, and in this case, natural fractures can be the cause of many adverse effects during a fracture treatment. Natural fractures can influence the overall geometry and effectiveness of the hydraulic fracture by: (1) arresting the vertical or lateral growth, (2) reducing total fracture length via fluid leakoff, (3) limiting proppant transport and placement, and (4) enhancing the creation of multiple or secondary fractures rather than a single planar hydraulic fracture. The result may range from negligible to catastrophic depending on the values of the ancillary treatment and reservoir parameters, such as the treating pressure, in-situ stresses, pore pressure, orientations of the natural fractures relative to principal in-situ stresses, spacing and distribution of the natural fractures, permeability, etc. Field observations from mineback experiments at DOE's Nevada Test Site and the multiwell experiment in Colorado, laboratory tests, and analyses of these data are integrated to describe the complex fracture behavior found and to provide guidelines for predicting when this complex fracturing will occur.

Teufel, L.W.; Warpinski, N.R.

1988-02-01

21

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

22

Method for enhancement of sequential hydraulic fracturing using control pulse fracturing  

SciTech Connect

A method is described for creating multiple sequential hydraulic fractures via hydraulic fracturing combined with controlled pulse fracturing where two wells are utilized comprising: (a) drilling and completing a first and second well so that the wells will be in fluid communication with each other after subsequent fracturing in each well; (b) creating more than two simultaneous multiple vertical fractures via a controlled pulse fracturing method in the second well; (c) thereafter hydraulically fracturing the reservoir via the first well thereby creating fractures in the reservoir and afterwards shutting-in the first well without any induced pressure; (d) applying thereafter hydraulic pressure to the reservoir via the second well in an amount sufficient to fracture the reservoir thereby forming a first hydraulic fracture perpendicular to the least principal in-situ stress; (e) maintaining the hydraulic pressure on the reservoir while pumping via the second well alternate slugs of a thin-fluid spacer and a temporary blocking agent having a proppant therein whereupon a second hydraulic fracture is initiated; (f) maintaining the hydraulic pressure on the second well while pumping alternate slugs of spacer and blocking agent into the second hydraulic fracture thereby causing the second hydraulic fracture to propagate away from the first hydraulic fracture in step (e) in a curved trajectory which intersects a fracture created in the first well; (g) maintaining the hydraulic pressure while pumping as in step (f) whereupon another hydraulic fracture initiates causing another curved fracture trajectory to form and intersect the fracture created in the first well; and (h) repeated steps (f) and (g) until a desired number of hydraulic fractures are created which allows a substantial improvement in removing a natural resource from the reservoir.

Jennings, A.R. Jr.; Strubhar, M.K.

1993-07-20

23

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

24

Hydraulic fracturing after water pressure control blasting for increased fracturing  

Microsoft Academic Search

Traditional hydraulic fracturing techniques generally form main hydraulic cracks and airfoil branch fissures, but main hydraulic cracks are relatively few in number. Hydraulic fracturing after water pressure control blasting can transform the structure of coal and rock mass. Experiments prove that it is an effective method for increasing the number and range of hydraulic cracks, as well as for improving

Bingxiang Huang; Changyou Liu; Junhui Fu; Hui Guan

2011-01-01

25

Mapping of hydraulic fractures from tiltmeter measurements  

NASA Astrophysics Data System (ADS)

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

Lecampion, B.; Jeffrey, R.

2003-12-01

26

Hydraulic Fracturing Near Interfaces.  

National Technical Information Service (NTIS)

Theoretical and experimental studies are being conducted of pressure driven fractures near interfaces that separate differing materials. When a crack propagates in material A toward a well bonded interface at half the dilatational wave speed, there is an ...

R. J. Shaffer M. E. Hanson G. D. Anderson

1979-01-01

27

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

28

Hydraulic fracturing method  

Microsoft Academic Search

A method of fracturing subterranean formations employs propping agent particles composed of resin-filled or fiber-reinforced cement pellets or resin-filled clinker. The cement pellets are impregnated with a resinous material, or reinforced with fibrous material, or both. The cement clinker particles also are impregnated with a resinous material. Laboratory tests show that this propping agent has less tendency to crush than

Cooke; C. E. Jr

1975-01-01

29

Monitoring hydraulic fracture growth: Laboratory experiments  

Microsoft Academic Search

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

Jeroen Groenenboom; Dirkjan B. van Dam

2000-01-01

30

Locating hydraulically active fracture planes  

SciTech Connect

If analysis of the microseismicity accompanying fluid injections is to be of maximum use in predicting hot dry rock (HDR) reservoir performance, it should lead to the determination of both the rock volume and active flowing surface area of the reservoir. In the granitic rock at the HDR geothermal site at Fenton Hill, New Mexico, the micro-earthquakes located during hydraulic fracturing occur in large three-dimensional volumes called seismic clouds. Cores cut from the region prior to fracturing show numerous planar fractures, some mineral-filled, at virtually random orientations. Evidence supports the hypothesis that only a few of these planes make up the flow path between wells for most of the injected fluid. If this is indeed the case, then it is necessary to be able to distinguish between fractures that accept flow from those which do not. We accomplish this by defining “flow-probable” planes to be those which have seismicity located relatively farther away from lines where other planes intersect. We show that these flow probable planes intercept wellbores at locations where other data confirm the presence of hydraulically active fractures.

Malzahn, Mark; Dreesen, Donald; Fehler, Michael

1988-01-01

31

Hydraulic Fracturing of Jointed Formations  

Microsoft Academic Search

Measured by volume, North America's largest hydraulic fracturing operations have been conducted at Fenton Hill, New Mexico to create geothermal energy reservoirs. In the largest operation 21,000 m³ of water were injected into jointed granitic rock at a depth of 3.5 km. Microearthquakes induced by this injection were measured with geophones placed in five wells drilled into, or very close,

H. D. Murphy; M. C. Fehler

1986-01-01

32

Influence of natural fractures on hydraulic fracture propagation  

Microsoft Academic Search

Hydraulic fracturing has become a valuable technique for the stimulation of oil, gas, and geothermal reservoirs in a variety of reservoir rocks. In many applications, only short fractures are needed for economic production. In low-permeability reservoirs, however, long penetrating fractures are generally needed, and in this case, natural fractures can be the cause of many adverse effects during a fracture

L. W. Teufel; N. R. Warpinski

1988-01-01

33

Hydraulic fracture with multiple segments II. Modeling  

Microsoft Academic Search

It is now well recognized that multiple fracturing, hydraulic fracture (HF) process zone, fracture width vs. height, and net-pressure calibration procedures are inter-related critical issues that need to be studied for making significant improvements in HF treatment design. To the best of our knowledge, there are no systematic studies of multiple HFs. Multiple fractures can occur as a result of

Leonid N. Germanovich; Lev M. Ring; Dmitriy K. Astakhov; Jacob Shlyapobersky; Michael J. Mayerhofer

1997-01-01

34

Hydraulic Fracturing Return Waters and Legacy Landscapes  

Microsoft Academic Search

Hydraulic fracturing of gas-bearing shales to enhance recovery is growing increasingly common globally. However, disposal of return water remains a challenge, particularly in humid environments where evapoconcentration potential is limited. Further, return water typical of recent activity in the Marcellus Shale in the eastern United States is substantially saltier relative to other shales where hydraulic fracturing has been employed. This

D. J. Bain; A. R. Michanowicz; K. J. Ferrar

2010-01-01

35

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

36

Hydraulic fracturing with chlorine dioxide cleanup  

Microsoft Academic Search

This patent describes a method for fracturing a subterranean formation penetrated by a wellbore. It comprises: injecting a fracturing fluid into the formation to form a vertical fracture therein, the fracturing fluid being gelled with a polymer selected from guar, guar derivatives, acrylamide, acrylamide derivatives, cellulose, cellulose derivatives, and mixtures thereof and crosslinked with an organometallic crosslinking compound and having

D. A. Williams; J. C. Newlove; R. L. Horton

1990-01-01

37

Sensitivity of time-lapse seismic data to fracture compliance in hydraulic fracturing  

NASA Astrophysics Data System (ADS)

We study the sensitivity of seismic waves to changes in the fracture normal and tangential compliances by analysing and numerically solving the fracture sensitivity wave equation, which is derived by differentiating the elastic wave equation with respect to the fracture compliance. The sources for the sensitivity wavefield are the sensitivity moments, which are functions of fracture compliance, background elastic properties and the stress acting on the fracture surface. Based on the analysis of the fracture sensitivity wave equation, we give the condition for the weak scattering approximation to be valid for fracture scattering. We study the sensitivity of P and S waves to fracture normal and tangential compliances, respectively, by separating the seismic wavefield and the sensitivity field into P and S components. In the numerical simulations of a single fracture in a homogeneous medium, we study the effect of fracture compliances, source incident angle and background elastic properties on the sensitivity field. We also discuss the sensitivity of seismic data to the compliances of vertical and horizontal fractures, respectively, for surface and borehole acquisitions. Under the weak scattering approximation, we find that the percentage change of fracture compliance in hydraulic fracturing is equal to the percentage change of the recorded time-lapse seismic data. This could provide a means for designing and interpreting experiments that can potentially be used to monitor the opening/closing of a fracture in hydraulic fracturing through time-lapse seismic surveys.

Fang, Xinding; Shang, Xuefeng; Fehler, Michael

2013-09-01

38

Hydraulic Fracturing in Saturated Cohesionless Materials  

NASA Astrophysics Data System (ADS)

Based on the developed experimental techniques, hydraulic fracturing in particulate materials has been directly observed in the laboratory. As a result, we suggested several mechanisms of hydraulic fracturing in particulate materials and determined relevant scaling relationships (e.g., the interplay between elastic and plastic processes). While the ongoing work is likely to change at least some conclusions, it is important that the results reported in this work appear to form the framework for modeling and, perhaps, even for (qualitative) interpretation of field data. The observed fracture geometry and the measured pressure injection curves suggest that hydraulic fracturing occurs in soft sediments in the following sequence: (i) cavity expansion, (ii) fracture front initiation, and (iii) propagation of the developed fracture. Our experiments show that liquid can indeed propagate as a crack-like feature when injected into cohesionless saturated materials. Laboratory observations suggest that at the initial stage, the cavity expansion process ends with fracture initiation. Sometimes, the growing fracture resembles penetration of one movable material into another less movable material, which may be a manifestation of the Taylor-like instability. 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. Additionally, an important characteristic feature of fractures in our experiments is the bluntness of the fracture tip, which suggests that plastic deformation at the fracture tip is important. Scaling indicates that fluid pressure does not decrease considerably along the fracture, due to the wide fracture aperture. However, there is a high pressure gradient in the leak-off zone in the direction normal to the fracture. Scaling also suggests the importance of fluid leaf-off in the cavity expansion and, possibly, in the fracture propagation process. First estimates show that large openings at the fracture tip correspond to large fracture energy, an order or two greater than for typical rocks. Unfortunately, it is not currently clear what defines the characteristic dimension at the process (tip) zone, which does not allow devising a comprehensive theoretical model. Without a model, it is not clear how to estimate an in-situ value of the fracture energy (or the corresponding value of the effective fracture toughness), that is, how to "extract" the fracture energy from available data of hydraulic fracturing tests or observations on natural hydraulic fractures (e.g., sand dikes propagated through unconsolidated sediments). However, it may still be possible that the fracture in field conditions is similar to that in conventional cohesive materials. Since what have been observed so far does not contradict to the condition of autonomity at the fracture tip (front), a tip-scale (local) fracture criterion still may be feasible to develop.

Germanovich, L. N.; Hurt, R. S.; Huang, H.

2007-12-01

39

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

40

New Proppant for Deep Hydraulic Fracturing  

Microsoft Academic Search

Much work has focused on developing and evaluating various materials for use as proppants for hydraulic fracturing. Sand is used most often as a fracturing proppant in shallow wells. Deep wells with high closure stresses require a proppant, such as sintered bauxite, that will not crush under adverse conditions. Ceramic and zirconium oxide beads and resin-coated sand proppants also have

David Underdown; Kamalendu Das

1985-01-01

41

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

42

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 end of a protruding turbidite complex through use of hydraulically fractured horizontal of high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than conventional vertical wells while maintaining vertical communication between thin interbedded layers and the well bore.

Mike L. Laue

1998-05-29

43

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

44

The hydraulic fracturing of geothermal formations  

SciTech Connect

Hydraulic fracturing has been attempted in geothermal formations as a means to stimulate both production and injection wells. Since most geothermal formations contain fissures and on occasion massive natural fissures, the production behavior of the man-made fractures results in certain characteristic trends. A model is offered that allows the presence of a finite or infinite conductivity fracture intercepting a fissured medium. The method is based on a numerical discretization of the formation allowing transient interporosity flow. Type curves for pressure drawdown and cumulative production are given for infinite acting and closed reservoirs. Since most of the fissured formations exhibit a degree of anisotropy, the effects of the orientation of the hydraulic fracture with respect to the fissure planes, and of the ratio between the directional permeabilities are then discussed. Guidelines are offered as to the size of appropriate stimulation treatments based on the observed fissured behavior of the reservoir.

Naceur, K. Ben; Economides, M.J.; Schlumberger, Dowell

1988-01-01

45

Interaction between injection points during hydraulic fracturing  

NASA Astrophysics Data System (ADS)

We study the geomechanical stress interaction between two injection points during hydraulic fracturing (hydrofracking) and how this interaction in combination with disorder influences the fracturing process. To this end, we develop an effective continuum model of the hydrofracking of heterogeneous poroelastic media that captures the coupled dynamics of the fluid pressure and the fractured rock matrix and models both the tensile and shear failure of the rock. For injection points that are separated by less than a critical correlation length, our numerical simulations show that the fracturing process around each point is strongly correlated with the position of the neighboring point. The magnitude of the correlation length depends on the degree of heterogeneity of the rock and is on the order of 30-45 m for rocks with low permeabilities. In the strongly correlated regime, we predict a novel effective fracture force that attracts the fractures toward the neighboring injection point.

Hals, Kjetil M. D.; Berre, Inga

2012-11-01

46

The use of broadband microseisms for hydraulic fracture mapping  

Microsoft Academic Search

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

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

1993-01-01

47

Hydraulic fracture with multiple segments I. Observations and model formulation  

Microsoft Academic Search

Hydraulic fracturing is a widely used technology to enhance oil and gas production. Recent publications in the Petroleum Industry indicate that hydraulic fracturing may be a great deal more complex than current modeling can capture. We therefore present a critical literature review of actual observations indicating that hydraulic fractures are not single, symmetric and planar features in the rock. These

Leonid N. Germanovich; Dmitriy K. Astakhov; Michael J. Mayerhofer; Jacob Shlyapobersky; Lev M. Ring

1997-01-01

48

New proppant for deep hydraulic fracturing  

Microsoft Academic Search

Much work has been done in the development and evaluation of various materials for use as proppants for hydraulic fracturing. Sand is most often used as a frac proppant in shallow wells. Deep wells having high closure stresses require a proppant such as sintered bauxite which will not crush under such adverse conditions. Proppants such as ceramic and zirconium oxide

D. R. Underdown; K. Das

1982-01-01

49

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

50

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

51

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

SciTech Connect

This project attempts to demonstrate the effectivensss of exploiting thin-layered, low energy deposits at the distal margin of a propagating turbinite complex through u se of hydraulically fractgured horizontal of high-angle wells. TGhe combinaton of a horizontal or high-angle weoo 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.

Mike L. Laue

1998-02-05

52

Numerical analysis of hydraulically-driven fractures  

SciTech Connect

A general method-of-lines numerical approach for modeling hydraulically driven fractures is developed and tested. The methodology employs several novel features: a straining coordinate system that elongates as the fracture grows, an evolutionary equation to describe growth of the fracture length, direct treatment of the fluid/elastic-solid coupling, and a control volume equation which governs fluid motion near the tip and thus circumvents local degeneracy of the differential equations. Spacial discretization of the governing equations leads to a nonsparse system of implicit, coupled ordinary differential equations that is solved for time derivatives that are then integrated with a Runge-Kutta algorithm. The numerical solutions agree very well with known simularity solutions for laminar and for turbulent flow. New solutions for nonsimilar flows are also presented and these converge to proper limits as the fracture becomes very long. Acceptable accuracy, in all cases, is obtained using a very few numerical grid points and with modest execution times.

Nilson, R.H.

1982-04-01

53

Hydraulic fracturing process using a polymer gel  

SciTech Connect

This patent describes a fracturing process applied to a subterranean hydrocarbon-bearing formation below an earthen surface in fluid communication with a wellbore comprising: (a) premixing a fracturing fluid at the surface comprising a gel breaker and a gelation solution consisting essentially of an aqueous solvent, a water-soluble acrylamide polymer selected from the group consisting of polyacrylamide and partially hydrolyzed polyacrylamide, and a crosslinking agent formed of at least one chromium III species complexed with at least one carboxylate species selected from the group consisting of propionate, acetate, lactate, and mixtures thereof; (b) at least partially gelling the gelation solution at the surface to form a gel; and (c) injecting the fracturing fluid into the formation via the wellbore at a pressure sufficient to hydraulically fracture the formation.

Sydansk, R.D.

1988-10-25

54

Distribution of propping agents in vertical fractures  

Microsoft Academic Search

An experimental study has been made of the distribution of propping agents in vertical fractures. The results indicate that propping agent distribution may be described by 2 parameters: equilibrium velocity, which represents the velocity necessary to maintain the propping agents suspended in the fracturing fluid, and the bank build-up constant, which describes the rate of propping agent deposition when the

R. E. Babcock; C. L. Prokop; R. O. Kehle

1967-01-01

55

Rio Blanco massive hydraulic fracture: project definition  

SciTech Connect

A recent Federal Power Commission feasibility study assessed the possibility of economically producing gas from three Rocky Mountain basins. These basins have potentially productive horizons 2,000 to 4,000 feet thick containing an estimated total of 600 trillion cubic feet of gas in place. However, the producing sands are of such low permeability and heterogeneity that conventional methods have failed to develop these basins economically. The Natural Gas Technology Task Force, responsible for preparing the referenced feasibility study, determined that, if effective well stimulation methods for these basins can be developed, it might be possible to recover 40 to 50 percent of the gas in place. The Task Force pointed out two possible underground fracturing methods: Nuclear explosive fracturing, and massive hydraulic fracturing. They argued that once technical viability has been demonstrated, and with adequate economic incentives, there should be no reason why one or even both of these approaches could not be employed, thus making a major contribution toward correcting the energy deficiency of the Nation. A joint Government-industry demonstration program has been proposed to test the relative effectiveness of massive hydraulic fracturing of the same formation and producing horizons that were stimulated by the Rio Blanco nuclear project.

Not Available

1976-01-01

56

Prop Transport in Vertical Fractures  

Microsoft Academic Search

The settling velocity of particles falling through a fracturing fluid determines, in part, the final distribution of propping agent in a fracture. In this study, two different experimental models have been used to obtain particle settling data. One model consists of a parallel plate apparatus in which the shear on the fluid is provided by a moving belt and the

Peter Clark; Francis Manning; Jamal Quadir; Nihalz Guler

1981-01-01

57

Comparison of methods for measuring vertical hydraulic properties in a sedimentary rock aquifer  

NASA Astrophysics Data System (ADS)

The characterization of groundwater flow in fractured bedrock aquifers is presently based on a variety of hydraulic testing methods. Pumping tests are often employed, the interpretation of which are based on models derived for porous media environments that do not fully represent the complexities of fractured rock settings. In this paper, we measure aquifer properties using a variety of testing methods in order to evaluate which methods are best capable of producing reliable parameter estimates. The study was performed in a fractured sedimentary rock aquifer using four different field methods: constant head tests conducted using a straddle-packer system, pulse interference tests conducted under open-hole conditions, 12-hour isolated interval pumping tests and 48-hour open-hole pumping tests. Using the results of the constant head tests as the most reliable method for estimation of hydraulic conductivity and specific yield, the results obtained using the other three methods were compared with particular emphasis on the estimation of vertical hydraulic parameters in this setting. The effects of test measurement scale on hydraulic parameter estimates were also investigated. Evaluation of the open-hole pumping test data was performed using an analytical model that accommodates multiple horizontal fractures and a connection to a free surface boundary. The comparison shows that estimates of horizontal hydraulic conductivity were not dependent on test method with all methods providing equivalent results. Open-well pumping tests, however, were found not to reliably estimate values of vertical hydraulic conductivity and specific yield for this setting. Alternatively, pulse interference tests conducted under open-hole conditions may offer a less time-intensive option to constant head injection tests for determining vertical hydraulic parameters in a sedimentary rock setting.

Novakowski, Kent; Worley, Jessica

2013-04-01

58

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

SciTech Connect

This report describes the work performed during the fourth 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 artificially fractured cores (AFCs) and X-ray CT scanner to examine the physical mechanisms of bypassing in hydraulically fractured reservoirs (HFR) and naturally fractured reservoirs (NFR) that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. In Chapter 1, we worked with DOE-RMOTC to investigate fracture properties in the Tensleep Formation at Teapot Dome Naval Reserve as part of their CO{sub 2} sequestration project. In Chapter 2, we continue our investigation to determine the primary oil recovery mechanism in a short vertically fractured core. Finally in Chapter 3, we report our numerical modeling efforts to develop compositional simulator with irregular grid blocks.

David S. Schechter

2005-04-27

59

Rulison Field Massive Hydraulic Fracturing Experiment. Final Report.  

National Technical Information Service (NTIS)

One of the seven producing gas wells in the Rulison Field, Garfield County, Colorado, was selected for a massive hydraulic fracturing experiment. The fracture treatment (Aug. 1976) was applied in two stages treating separately the gross perforated interva...

M. Reynolds

1977-01-01

60

Hydraulic Fracturing and Propping Tests at Yakedake Field in Japan.  

National Technical Information Service (NTIS)

Hydraulic fracturing experiments have been conducted at Yakedake field in Gifu prefecture, Japan. From the data obtained during the fracturing operation, the open-hole section permeability was estimated of the wellbore, the minimum pressure required to pr...

T. Yamaguchi K. Seo S. Suga T. Itoh M. Kuriyagawa

1984-01-01

61

Modeling Vertical Flow Treatment Wetland Hydraulics to Optimize Treatment Efficiency.  

National Technical Information Service (NTIS)

An upward Vertical Flow Treatment Wetland (uVFTW) at Wright Patterson AFB designed to bioremediate contaminated groundwater exhibits hydraulic short-circuiting. Prior studies estimated that groundwater flowed through less than 50% of the wetland's volume,...

I. D. Roen

2011-01-01

62

Hydraulic fracturing method employing special sand control technique  

SciTech Connect

A subsurface oil or gas reservoir is hydraulically fractured by injecting a fracturing fluid through perforations in the casing of a well penetrating into such subsurface reservoir. The fracturing fluid contains a clay stabilizing agent for stabilizing clay particles or fines along the face of the resulting formation fracture. A proppant comprising a gravel packing sand is injected into the fracture. Oil or gas is then produced from the reservoir through the fracture into the well.

Stowe, L. R.; Strubbar, M. K.

1985-10-29

63

Prop transport in vertical fractures  

SciTech Connect

The settling velocity of particles falling through a fracturing fluid determines, in part, the final distribution of propping agent in a fracture. In this study, two different experimental models have been used to obtain particle settling data. One model consists of a parallel plate apparatus in which the shear on the fluid is provided by a moving belt and the other consists of a concentric cylinder device. Data from each device are reported. Initial results from each method have been found to be comparable. A comparison of the experimental settling velocities with settling velocities calculated by Stokes' Law are also presented. 17 refs.

Clark, P.E.; Manning, F.S.; Quadir, J.A.; Guler, N.

1981-01-01

64

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

Federal Register 2010, 2011, 2012, 2013

...Public Teleconference of the Hydraulic Fracturing Research Advisory Panel AGENCY...public teleconference of the Hydraulic Fracturing Research Advisory Panel to...the Potential Impacts of Hydraulic Fracturing on Drinking Water...

2013-04-05

65

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

Federal Register 2010, 2011, 2012, 2013

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

2012-06-26

66

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

Federal Register 2010, 2011, 2012, 2013

...for Information To Inform Hydraulic Fracturing Research Related to Drinking...the potential impacts of hydraulic fracturing on drinking water resources...the relationship between hydraulic fracturing and drinking water...

2013-04-30

67

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

Code of Federal Regulations, 2010 CFR

...State - administered program--Hydraulic Fracturing of Coal Beds.] 40 PROTECTION...State-administered program--Hydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State...

2009-07-01

68

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

Federal Register 2010, 2011, 2012, 2013

...for Information To Inform Hydraulic Fracturing Research Related to Drinking...the potential impacts of hydraulic fracturing on drinking water resources...the relationship between hydraulic fracturing and drinking water...

2012-11-09

69

Shutting off water in vertical fractures  

Microsoft Academic Search

This is a method of vertical fracturing of oil and gas wells to increase oil production without proportionally increasing the water production. The method consists of passing into the fracture a mixture of a carrier fluid and a particle-form propping agent, followed by a particulate sealing material composed of a material different from the particle-form propping agent. The particle-form propping

L. R. Kern; R. E. Wyant; T. K. Perkins

1966-01-01

70

Economic Recovery of Oil Trapped at Fan Margins Using High Angle Wells 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.

Mike L. Laue

1997-10-30

71

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

72

Extracting energy from hydraulically-fractured geothermal reservoirs  

Microsoft Academic Search

It has been proposed that man-made geothermal energy reservoirs can be created by drilling into relatively impermeable rock to a depth where the temperature is high enough to be useful; creating a large hydraulic fracture; and then completing the circulation loop by drilling a second hole to intercept the hydraulic fracture. An inlet and an outlet pipe are used to

R. D. McFarland; H. D. Murphy

1976-01-01

73

Microseismic Signatures of Hydraulic Fracture Propagation in Hydrocarbon Reservoirs  

Microsoft Academic Search

Hydraulic fracturing is often used in oil industry to increase the productivity of hydrocarbon reservoirs, which suffer of decreasing hydrocarbon pressure and permeability of gas\\/oil-bearing sediments. The generated hydraulic fracture is accompanied by shear cracks, which emit acoustic energy that is recorded by array of geophones. The hydrofracture is usually characterized by elongation of accompanying hypocenters in one direction that

T. Fischer; L. Eisner; S. Hainzl; Z. Jechumtalova

2006-01-01

74

FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS  

EPA Science Inventory

Hydraulic fracturing, a technique commonly used to increase the yields of oil wells, could improve the effectiveness of several methods of in situ remediation. This project consisted of laboratory and field tests in which hydraulic fractures were created in soil. Laboratory te...

75

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

76

Sensors for hydraulic-induced fracturing characterization  

NASA Astrophysics Data System (ADS)

Hydraulic induced fracturing (HIF) in oil wells is used to increase oil productivity by making the subterranean terrain more deep and permeable. In some cases HIF connects multiple oil pockets to the main well. Currently there is a need to understand and control with a high degree of precision the geometry, direction, and the physical properties of fractures. By knowing these characteristics (the specifications of fractures), other drill well locations and set-ups of wells can be designed to increase the probability of connection of the oil pockets to main well(s), thus, increasing productivity. The current state of the art of HIF characterization does not meet the requirements of the oil industry. In Mexico, the SENER-CONACyT funding program recently supported a three party collaborative effort between the Mexican Petroleum Institute, Schlumberger Dowell Mexico, and the Autonomous University of Juarez to develop a sensing scheme to measure physical parameters of a HIF like, but not limited to pressure, temperature, density and viscosity. We present in this paper a review of HIF process, its challenges and the progress of sensing development for down hole measurement parameters of wells for the Chicontepec region of Mexico.

Mireles, Jose, Jr.; Estrada, Horacio; Ambrosio, Roberto C.

2011-05-01

77

Stimulating tight sands in the presence of weak stress barriers by modified hydraulic fracturing techniques: a status report  

SciTech Connect

Tight gas formations bounded by base rock and/or overlain by an overburden rock, that are not barriers to vertical fracture migration, are not amenable to successful large stimulation treatments by hydraulic fracturing as practiced today. Reservoirs of this nature are abundant. The example considered is the North Douglas Creek Arch field, east of Rangeley, Colorado. This work presents the preliminary findings of a project sponsored by the Gas Research Inst. of Chicago and conducted by Terra Tek Inc. of Salt Lake City and Chandler and Associates of Denver. The program is aimed toward developing technology that can provide deeply penetrating fractures in formations lacking barriers to vertical migration. Four prospective techniques are being evaluated in the laboratory and in the field: fracture initiation placement (perforation placement), fracture packing with lightweight additives, controlled process zone fracturing, and electric heating/fracturing followed by hydraulic fracturing. 10 references.

Ahmed, U.; Strawn, J.; Schmidt, R.; O'Shea, P.; Veghte, R.

1983-01-01

78

Convective Instabilities in Vertical Fractures and Faults  

Microsoft Academic Search

Natural convection of water contained in a vertical fracture or fault in which the temperature increases with depth is strongly influenced by the heat transport processes not only within the water itself but also by the heat transferred to and from the surrounding rock mass. The results of a linear stability analysis indicate that the critical Rayleigh number R* is

Hugh D. Murphy; Geosciences Division

1979-01-01

79

Numerical Well Test for Well with Finite Conductivity Vertical Fracture in Coalbed  

NASA Astrophysics Data System (ADS)

A new model is developed for the hydraulic fractured well in coalbed, by considering the following aspects: methane desorption phenomena, finite conductivity vertical fracture, and asymmetry of the fracture about the well. A new parameter is introduced to describe the storage of the fracture, which is named combined fracture storage. Another new concept called fracture asymmetry coefficient is used to define the asymmetry of the fracture about the well. FEM is used to solve the new mathematic model. Both well test type curve and seepage field are got and analyzed. The effects of combined fracture storage, desorption factor, the fracture conductivity, fracture asymmetry coefficient, etc. on type curve are all discussed in detail in this paper.

Liu, Y. W.; Ouyang, W. P.; Zhao, P. H.; Lu, Q.; Fang, H. J.

2011-09-01

80

Hydraulic fracturing and propping tests at Yakedake field in Japan  

SciTech Connect

Hydraulic fracturing experiments have been conducted at Yakedake field in Gifu prefecture, Japan. From the data obtained during the fracturing operation, the open-hole section permeability was estimated of the wellbore, the minimum pressure required to propagate the fracture, the impedances before and after the propping, and the earth stress normal to the fracture plane. The final fracture plane was also mapped with the microseismic events.

Yamaguchi, Tsutomu; Seo, Kunio; Suga, Shoto; Itoh, Toshinobu; Kuriyagawa, Michio

1984-01-01

81

Active and passive seismic imaging of a hydraulic fracture in diatomite  

SciTech Connect

This paper reports on a comprehensive set of experiments including remote- and treatment-well microseismic monitoring, interwell shear-wave shadowing, and surface tiltmeter arrays, that was used to monitor the growth of a hydraulic fracture in the Belridge diatomite. To obtain accurate measurements, and extensive subsurface network of geophones was cemented spanning the diatomite formation in three closely spaced observation wells around the well to be fracture treated. Data analysis indicates that the minifracture and main hydraulic fracture stimulations resulted in a nearly vertical fracture zone (striking N26{degrees}E) vertically segregated into two separate elements, the uppermost of which grew 60 ft above the perforated interval. The interwell seismic effects are consistent with a side process zone of reduced shear velocity, which remote-well microseismic data independently suggest may be as wide as 40 ft. The experiments indicate complicated processes occurring during hydraulic fracturing that have significant implications for stimulation, waterflooding, in fill drilling, and EOR. These processes are neither well understood nor included in current hydraulic fracture models.

Vinegar, H.J.; Wills, P.B.; De Martini, D.C. (Shell Development Co. (US))

1992-01-01

82

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

83

Use of hydraulic tests at different scales to characterize fracture network properties in the weathered-fractured layer of a hard rock aquifer  

Microsoft Academic Search

The hydrodynamic properties of the weathered-fractured layer of a hard-rock pilot watershed in a granitic terrain are characterized using hydraulic tests at different scales. The interpretation of numerous slug tests leads us to characterize the statistical distribution of local permeabilities in the wells. The application of flowmeter profiles during injection tests determines the vertical distribution of conductive fracture zones and

J. C. Maréchal; B. Dewandel; K. Subrahmanyam

2004-01-01

84

Mixed-mode Mechanism of Hydraulic Fracture Segmentation  

NASA Astrophysics Data System (ADS)

Mixed-mode I+III loading is one of the primary causes of fracture front segmentation. Although such segmented fractures have been observed both in nature and laboratory, we are not aware of direct laboratory experiments on the mode III mechanism of segmentation of hydraulically induced fractures. In this work, we developed a laboratory technique and a theoretical model for studying not only the effect of mode III loading on the onset of hydraulic fracture segmentation, but also the effect of segmentation on the subsequent growth of hydraulic fractures. In quasi-brittle materials, even a small mode III component may cause fracture segmentation due to a tensile stress field induced near the fracture front [Rice, 1968]. Previously, this has been confirmed in experiments with non-hydraulic fractures [Knauss, 1970; Cooke and Pollard, 1996]. In one occasion, quasi-hydraulic fractures propagated in fast, uncontrollable manner [Sommer, 1969]. This is why, we focused on controlled hydraulic fractures with a rather small KIII/KI ratio (1-10 %). For mixed mode I+III experiments, we used transparent, cylindrical PMMA samples with circular internal fractures perpendicular to the sample axis. Fracture orientation was controlled by thermoelastic stresses induced in each sample by preheating it before creating a fracture. In order to apply mode III loading to the initial fracture, a constant torque was applied to the specimen while fluid was injected into the fracture at a constant rate to pressurize it and to induce mode I loading. The velocity of fracture propagation was constrained by controlling the rate of fluid injection. In spite of a small magnitude of the mode III component, we observed segmented fracture fronts in all tested samples. The segments had similar dimensions and shape elongated around the perimeter of the initial fracture. When the fractures were further pressurized by injecting additional fluid into the sample, second-order segments developed along the fronts of the first-order segments. The obtained results indicate that, similar to the case of non-hydraulic fractures, a KIII/KI ratio as small as 1 % is sufficient for fracture front segmentation, even in materials as homogeneous and fracture resistant as PMMA. In reality, a small component of mode III is always expected, for example, due to slight deviations of a fracture shape from planar or interaction with boundaries or other fractures. As a result, front segmentation (at an appropriate scale) is likely to accompany the growth of most (if not all) real, sufficiently large fractures (hydraulic or not) in quasi-brittle materials, which is consistent with many observations of hydraulic fractures and magmatic dikes. However, the described above shape of segments in stable, controllable hydraulic fractures, which appeared in our experiments, was dramatically different from narrow lance-like segments, elongated in the direction of growth, of uncontrollable, unstable, non-hydraulic fractures that were propagated in a similar setting [Sommer, 1969; Hull, 1995]. We also developed a simple theoretical model, which is based on the beam asymptotic approximation. It appears that mechanical interaction between the segments and the parent fracture can be taken into account by considering an effective single fracture of equal total size. The model has one fitting parameter and shows good agreement with the experimental observations.

Hurt, R. S.; Germanovich, L.; Wu, R.

2006-12-01

85

Advanced hydraulic fracturing methods to create in situ reactive barriers  

SciTech Connect

This article describes the use of hydraulic fracturing to increase permeability in geologic formations where in-situ remedial action of contaminant plumes will be performed. Several in-situ treatment strategies are discussed including the use of hydraulic fracturing to create in situ redox zones for treatment of organics and inorganics. Hydraulic fracturing methods offer a mechanism for the in-situ treatment of gently dipping layers of reactive compounds. Specialized methods using real-time monitoring and a high-energy jet during fracturing allow the form of the fracture to be influenced, such as creation of assymmetric fractures beneath potential sources (i.e. tanks, pits, buildings) that should not be penetrated by boring. Some examples of field applications of this technique such as creating fractures filled with zero-valent iron to reductively dechlorinate halogenated hydrocarbons, and the use of granular activated carbon to adsorb compounds are discussed.

Murdoch, L. [FRX Inc., Cincinnati, OH (United States)]|[Clemson Univ., SC (United States). Dept. of Geological Sciences; Siegrist, B.; Meiggs, T. [Oak Ridge National Lab., TN (United States)] [and others

1997-12-31

86

Fluid-driven multiple fracture growth from a permeable bedding plane intersected by an ascending hydraulic fracture  

NASA Astrophysics Data System (ADS)

In bedded sedimentary rocks, the energy for spontaneous growth of multiple vertical fractures from a bedding plane may be provided by an overpressurized sublayer fracture that connects a fluid source to the bedding plane. In this paper, using our coupled deformation and flow model, we study the processes and mechanisms involved in the formation and interaction of closely space fractures from preexisting flaws or starter fractures located along the bedding plane. Fracture growth from multiple flaws can be convergent, parallel or divergent, depending on the factors like contrasts in moduli and far-field stresses, flaw sizes and locations, and initial bed conductivity, fluid viscosity, and injection rate, as well as time. The results presented here have been obtained for conditions where fluid viscous dissipation is dominant, in contrast to other results available in literature based on uniform pressure assumption equivalent to use of an inviscid fluid. It is demonstrated that the earlier a hydraulic fracture starts to extend, the more likely it is to become the primary fracture in a system of closely spaced fractures. The fracture closest to the fluid source typically grows faster as a result of a higher pressure level because viscous dissipation results in a decrease in pressure with distance from the fluid source. But its development does not completely inhibit the growth of other hydraulic fractures. Simultaneous growth of closely spaced fractures is supported by the local stress and energetic analyses, and the fracture distance can be very small. Their length to spacing ratio is accordingly much larger than that predicted previously. Under certain circumstances, a longer and more permeable fracture may grow to a greater extent than a shorter fracture closer to the fluid source, which may grow toward and merge with the longer fracture to create fracture clusters adjacent to a bedding plane.

Zhang, Xi; Jeffrey, Robert G.

2012-12-01

87

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

SciTech Connect

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

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

1997-03-01

88

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

89

Active seismic monitoring of hydraulic fractures in laboratory experiments  

Microsoft Academic Search

In scaled laboratory tests, we perform acoustic measurements in a time-lapse sequence to separate the fracture response from the background signal. Using both compressional and shear waves (that are very sensitive to fluid filled fractures) we can, not only detect the hydraulic fracture, but also characterize its shape and geometry during its growth. We show the application of the technique

C. J. de Pater; J. Groenenboom; D. B. van Dam; R. Romijn

2001-01-01

90

Stimulating Tight Sands in the Presence of Weak Stress Barriers by Modified Hydraulic Fracturing Techniques: A Status Report  

Microsoft Academic Search

Tight gas formations bounded by base rock and\\/or overlain by an overburden rock, that are not barriers to vertical fracture migration, are not amenable to successful large stimulation treatments by hydraulic fracturing as practiced today. Reservoirs of this nature are abundant. The example considered is the North Douglas Creek Arch field, east of Rangeley, Colorado. This work presents the preliminary

Usman Ahmed; Jon Strawn; Rich Schmidt; Patrick OShea; Richard Veghte

1983-01-01

91

Overview of current hydraulic fracturing design and treatment technology. Part 2  

SciTech Connect

Hydraulic fracturing has played a major role in enhancing petroleum reserves and daily production. The ''typical'' fracturing process consists of blending special chemicals to make the appropriate fracturing fluid, then mixing it with a propping agent (usually sand) and pumping it into the pay zone at sufficiently high rates and pressures that the fluid hydraulically wedges and extends a fracture. At the same time, the fluids carry the proppant deeply into the fracture. When done successfully, the propped open fracture creates a ''superhighway'' for oil and/or gas to flow easily from the extremities of the formation into the well. Note that the fracture has two wings extending in opposite directions from the well and that it is oriented more or less in the vertical plane. Other types (e.g., horizontal fractures) are known to exist. Some have been observed at relatively shallow depths (<2,000 ft (600 m)), but they comprise a relatively low percentage of the situations experienced to date. Hence, the discussion is directed primarily to vertical fractures.

Veatch, R.V. Jr.

1983-05-01

92

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

93

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

94

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...

95

Microseismicity Induced by Hydraulic Fracturing in Oil and Gas Wells  

Microsoft Academic Search

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, \\

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

2006-01-01

96

Evaluation of a downhole tiltmeter array for monitoring hydraulic fractures  

Microsoft Academic Search

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

N. R. Warpinski; P. T. Branagan; B. P. Engler; R. Wilmer; S. L. Wolhart

1997-01-01

97

How to evaluate productivity increase after vertical fracturing  

Microsoft Academic Search

Most methods of evaluating the productivity increase after vertical fracturing assumes that the fracture extends from top to bottom of the reservoir formation and that the propped height equals the created height. Field studies have shown that the propping agent is distributed in a vertical fracture until an equilibrium height is reached, after which all additional sand injected is washed

Kotb

1967-01-01

98

In situ stress determination from inversion of hydraulic fracturing data  

Microsoft Academic Search

The paper presents a new method, based on rigorous principles of mechanics, for determining the in-situ rock stress state based on hydraulic fracturing data. A solution can be obtained from a single data set which includes breakdown pressure, fracture angular position and trace angle. The inversion methodology is demonstrated on a case history from the Kuparuk River field, Alaska as

Jinsong Huang; D. V. Griffiths; Sau-Wai Wong

2011-01-01

99

Prediction of massive hydraulic fracturing from analyses of oriented cores  

Microsoft Academic Search

An attempt has been made to predict the orientation of massive hydraulic fractures stimulated between depths of 2316 and 2464 M within the Muddy J formation of the Wattenberg Gas Field, Colorado. Predictions were based upon a study of the properties of 3 oriented cores and 2 unoriented cores. A preferred orientation of fractures induced in point-load tests is found

J. M. Logan; L. W. Teufel

1978-01-01

100

The use of broadband microseisms for hydraulic-fracture mapping  

SciTech Connect

The authors conducted a series of hydraulic-fracture experiments to examine improvements in seismic-fracture diagnostic technology that are available with the application of advanced receiver capabilities. They present characteristics of the microseisms, tool response behavior, and the results of the tests.

Sleefe, G.E.; Warpinski, N.R.; Engler, B.P. [Sandia National Labs., Albuquerque, NM (United States)

1995-12-01

101

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

102

Physical and Numerical Modeling of Hydraulic Fracture Closure  

Microsoft Academic Search

This paper describes laboratory tests and numerical simulation of hydraulic fracture behavior during propagation and closure. The numerical results predicted the laboratory results during fracture propagation and closure. From the experiments and simulations, the paper provides recommendations for ensuring correct interpretation of field data.

Jean Desroches; Jeroen Groenenboom; Leen Weijers

1996-01-01

103

Downhole electro-hydraulic vertical shear wave seismic source  

SciTech Connect

A downhole electro-hydraulic vertical shear wave seismic source to be lowered into a wellbore is described comprising: a source cylindrical housing; a reaction mass means for generating seismic shear waves, said reaction mass means having an actuator with an actuator piston and actuator cylinder and located internal to said source cylindrical housing to isolate said actuator from wellbore fluid and pressure, said reaction mass including transversely formed holes through which hydraulic cylinders connected to contact pads pass, said holes having a significantly larger diameter than said hydraulic cylinders; a clamping means to clamp said source cylindrical housing to the wellbore, said clamping means including two serrated pads radiused to match an inside diameter of casing located in said wellbore and hydraulic cylinders having internal compact stacks of spring washers for retraction for actuating said serrated pads; a compact and soft urethane spring for suspending said reaction mass; and a threaded guide rod passing vertically through said urethane spring to allow spring compression to be adjusted until said actuator piston is precisely centered with no differential hydraulic pressure across said actuator piston.

Cole, J.H.

1993-07-20

104

Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, Apr 1June 30, 1997  

Microsoft Academic Search

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

Laue

1997-01-01

105

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

106

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

Microsoft Academic Search

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

R. Wilmer; N. R. Warpinski; T. B. Wright; P. T. Branagan; J. E. Fix

1995-01-01

107

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

108

A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development  

SciTech Connect

Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Thus, knowledge of conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fracture are created in the reservoir using hydraulic fracturing. At times, the practice aims to create a number of parallel fractures connecting a pair of wells. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have set out to develop advanced thermo-mechanical models for design of artificial fractures and rock fracture research in geothermal reservoirs. These models consider the significant hydraulic and thermo-mechanical processes and their interaction with the in-situ stress state. Wellbore failure and fracture initiation is studied using a model that fully couples poro-mechanical and thermo-mechanical effects. The fracture propagation model is based on a complex variable and regular displacement discontinuity formulations. In the complex variable approach the displacement discontinuities are defined from the numerical solution of a complex hypersingular integral equation written for a given fracture configuration and loading. The fracture propagation studies include modeling interaction of induced fractures with existing discontinuities such as faults and joints. In addition to the fracture propagation studies, two- and three-dimensional heat extraction solution algorithms have been developed and used to estimate heat extraction and the variations of the reservoir stress with cooling. The numerical models have been developed in a user-friendly environment to create a tool for improving fracture design and investigating single or multiple fracture propagation in rock.

Ahmad Ghassemi

2003-06-30

109

Etude sur la Propagation des Fractures Hydrauliques dans les Roches (Study on the Propagation of Hydraulic Fractures in Rocks).  

National Technical Information Service (NTIS)

The possibility of forming multiple hydraulic links between two deep wells by means of hydraulic fracturing was investigated. Isotropic rocks and those whose fracture behavior is anisotropic were considered. A mathematical model showed that for isotropic ...

F. H. Cornet

1981-01-01

110

Hydraulic transience and the role of bedding fractures in a bedrock aquitard, southeastern Wisconsin, USA  

NASA Astrophysics Data System (ADS)

Hydraulic heads in a dolomitic shale bedrock aquitard in Wisconsin, USA, are apparently not in equilibrium with drawdown in the underlying aquifer system caused by pumping for municipal supply over the last century. Measurements of head with depth, downhole geophysical logs, and estimates of hydraulic conductivity indicate very low vertical hydraulic diffusivity, and show that high horizontal permeability within the aquitard due to bedding-plane fracture zones can allow lateral groundwater flow. Unlike the hydrogeological conceptual models used in many investigations, flow in aquitards cannot always be inferred to be primarily one-dimensional and vertical. Failure to account for transient conditions and lateral flow in similar settings of intensive groundwater pumping could lead to error in estimates of aquitard leakage and underlying aquifer properties.

Eaton, Timothy T.; Bradbury, Kenneth R.

2003-09-01

111

On Mechanisms of Hydraulic Fracturing in Cohesionless Materials  

NASA Astrophysics Data System (ADS)

Based on the developed experimental techniques, hydraulic fracturing in particulate materials has been directly observed in the laboratory. We have conducted an experimental series by varying such controlling parameters as the properties of particulate materials and fracturing fluids, boundary conditions, initial stress states, and injection volumes and rates. As a result, we suggested some (hopefully, fundamental) mechanisms of hydraulic fracturing in particulate materials and determined some (hopefully, relevant) scaling relationships (e.g., the interplay between elastic and plastic processes). While the ongoing work is likely to change at least some conclusions, it is important that the results reported in this paper appear to form the framework for modeling and, perhaps, even for (qualitative) interpretation of some field data. The main conclusion of our work is that hydraulic fracturing in particulate materials is not only possible, but even probable if the fluid leakoff is minimized (e.g., high flow rate, high viscosity, or low permeability). The observed fracture geometry and the measured pressure injection curves suggest that hydraulic fracturing occurs in soft sediments in the following sequence: (i) cavity expansion before the injection pressure reaches its peak; (ii) fracture front initiation from the expanding cavity near the pressure peak; and (iii) propagation of the developed fracture after the peak. Another important conclusion of our work is that all parts of the 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). For the fracture initiation at the peak pressure (i.e., following the initial cavity expansion), there exists a threshold value of cohesion that results in compressive stresses everywhere in the particulate material. For less cohesion, the cohesive materials can be considered to be effectively cohesionless. Three main types of fracture fronts were observed in our laboratory experiments: round, beveled and fingered. Accordingly, three physical mechanisms of fracture propagation corresponding to the three observed front types were suggested. These are ``pile driving'' or cavity expansion, shear banding, and induced cohesion, which appear to be consistent with round, beveled, and fingered fracture fronts, respectively. It is important to emphasize the importance of leakoff effect on hydraulic fractures in particulate materials. In our experiments, fractures appear rather different compared to those in the no-leakoff case. The fluid leakoff region manifests itself as a (bubbly) layer around the fracture, which thins towards the fracture tip, which is similar to brittle fractures. Furthermore, even the tip details of these fractures remarkably resemble cracks in brittle materials. Therefore, currently available experimental observations suggest that even small leakoff may change the fracture pattern rather dramatically. For example, while at the stage of fracture initiation, the cavity expansion mechanism may still be important, the mechanism of induced cohesion may prevail at the developed stage of fracture growth.

Hurt, R. S.; Wu, R.; Germanovich, L.; Chang, H.; Dyke, P. V.

2005-12-01

112

Hydraulic fracturing using reinforced resin pellets  

Microsoft Academic Search

A method of fracturing subterranean formations surrounding oil wells, gas wells, and similar boreholes is presented. The method employs a propping agent which permits the fractures to be propped in a partial monolayer pattern. It has been found that fractures with surprisingly high conductivities can be obtained by use of propping agents composed of reinforced synthetic resins. Synthetic resins without

1972-01-01

113

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

NASA Astrophysics Data System (ADS)

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

Shemeta, J. E.

2011-12-01

114

Influences of Fracture Aperture and Roughness on Hydraulic Conductivity in Fractured Rock Mass  

NASA Astrophysics Data System (ADS)

A comparison on the empirical and analytical solutions to a single fracture flow is presented to obtain an in-depth understanding on the fluid flow in rock fractures. In order to establish a possible relationship, we study the creeping flow through a fracture of sinusoidally-varying aperture that is symmetric about its mid-plane. The results show that hydraulic aperture decreases as the roughness increases and mechanical aperture decreases. When the mechanical aperture is less than the critical value, the analytical solution will overestimate the hydraulic conductivity. When the mechanical aperture is larger than the critical value, the empirical solution will overestimate the hydraulic conductivity.

Sun, J. P.; Zhao, Z. Y.

2011-09-01

115

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

116

Hydraulic parameters of fracture networsk for dual porosity groundwater modeling  

Microsoft Academic Search

Relatively large-scale or bulk processes of groundwater flow phenomena in a fractured porous medium can be described by adopting\\u000a the dual porosity groundwater model. To analyze groundwater flow with the dual porosity model, relevant hydraulic parameters\\u000a must be determined. Laboratory experiments or field well tests can be applied to estimate the hydraulic parameters, but the\\u000a values thus estimated represent localized

T. Kim; K. K. Lee

2000-01-01

117

Massive hydraulic fracture mapping and characterization program. First annual report, August 1975July 1976  

Microsoft Academic Search

The FY'76 major objectives of the Massive Hydraulic Fracture Mapping and Characterization Program were to assess the feasibility of the surface electrical potential and surface seismic systems to provide locational information on hydraulically created fracture systems. The surface electrical potential system has demonstrated the capability to provide information on fracture azimuthal orientation, asymmetry of fracture, and direction of major fracture

R. P. McCann; R. G. Hay; L. C. Bartel

1977-01-01

118

Radiographic features of vertically fractured, endodontically treated maxillary premolars  

Microsoft Academic Search

Objective. The purpose of this study was to evaluate the most frequent radiographic appearance of bony lesions associated with vertically fractured roots of endodontically treated maxillary premolars. Study Design. The radiographic features of 102 endodontically treated teeth and their periradicular areas (51 with and 51 without vertically fractured roots) were evaluated and compared. Results. The predominant appearance of the periradicular

Aviad Tamse; Zvi Fuss; Joseph Lustig; Yehuda Ganor; Israel Kaffe

1999-01-01

119

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

Federal Register 2010, 2011, 2012, 2013

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

2010-06-25

120

Numerical Modeling of Hydraulic Fractures Interaction in Complex Naturally Fractured Formations  

NASA Astrophysics Data System (ADS)

A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. A method for computing the stress shadow from fracture branches in a complex hydraulic fracture network (HFN) based on an enhanced 2D displacement discontinuity method with correction for finite fracture height is implemented in UFM and is presented in detail including approach validation and examples. The influence of stress shadow effect from the HFN generated at previous treatment stage on the HFN propagation and shape at new stage is also discussed.

Kresse, Olga; Weng, Xiaowei; Gu, Hongren; Wu, Ruiting

2013-05-01

121

A demographic analysis of vertical root fractures.  

PubMed

Teeth with vertical root fractures (VRFs) have complete or incomplete fractures that extends through the enamel, dentin and pulp, down the long axis of the tooth. Several different variables were investigated and statistically evaluated as to their correlation with the presence of VRFs. Specifically analyzed were gender, tooth location, age, radiographic and clinical findings, bruxism, and pulpal status. The data were collected from three different endodontists, from three different geographic locations, comprising a total of 227 teeth. Although VRFs may occur in conjunction with any of the parameters investigated, only certain factors were found to occur in a significant number of cases. The results indicate that VRFs are statistically more prevalent in mandibular molars and maxillary premolars. They are associated with periradicular bone loss, pain to percussion, extensive restorations, and seem to occur more often in females and older patients. However, VRFs are not necessarily related to periapical bone loss, a widening of the periodontal ligament space, associated periodontal pockets, a sinus tract, particular pulpal status, or bruxism. PMID:17174672

Cohen, Stephen; Berman, Louis H; Blanco, Lucia; Bakland, Leif; Kim, Jay S

2006-10-13

122

Rulison Field massive hydraulic fracturing experiment. Final report  

Microsoft Academic Search

One of the seven producing gas wells in the Rulison Field, Garfield County, Colorado, was selected for a massive hydraulic fracturing experiment. The fracture treatment (Aug. 1976) was applied in two stages treating separately the gross perforated intervals from 6198 to 6363 ft (Stage 1) and 5170 to 5630 ft (Stage 2). 485,000 gallons of gelled water, 1,070,000 pounds of

M. Jr

1977-01-01

123

Stress determination from hydraulic fracturing tests: the system stiffness approach  

Microsoft Academic Search

Hydraulic fracturing tests with mud is the most inexpensive method for determining the minor in situ horizontal stress in deep petroleum wells.This paper presents a unified model of pump-in\\/shut-in and pump-in\\/flowback tests. The key element of the model is the system stiffness resulting from the stiffness of the fluid volume pressurised, and the stiffness due to the fracture.It is shown

A. M Raaen; E Skomedal; H Kjørholt; P Markestad; D Økland

2001-01-01

124

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

125

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

126

Aligned vertical fractures, HTI reservoir symmetry, and Thomsenseismic anisotropy parameters  

SciTech Connect

The Sayers and Kachanov (1991) crack-influence parametersare shown to be directly related to Thomsen (1986) weak-anisotropyseismic parameters for fractured reservoirs when the crack density issmall enough. These results are then applied to seismic wave propagationin reservoirs having HTI symmetry due to aligned vertical fractures. Theapproach suggests a method of inverting for fracture density from wavespeed data.

Berryman, James G.

2007-06-27

127

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 programâHydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State of Alabama,...

2012-07-01

128

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

Federal Register 2010, 2011, 2012, 2013

...of the Potential Impacts of Hydraulic Fracturing on Drinking Water...emerging information related to hydraulic fracturing to the Panel...on the potential impacts of hydraulic fracturing on drinking water...agenda and other materials in support of the November 20,...

2013-09-10

129

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 programâHydraulic Fracturing of Coal Beds. The UIC program for hydraulic fracturing of coal beds in the State of Alabama,...

2013-07-01

130

Abnormal treating pressures in MHF (massive hydraulic fracturing) treatments  

Microsoft Academic Search

Abnormal treating pressures are observed during massive hydraulic fracturing (MHF) treatments in the Mesa Verde Formation of the Piceance Basin, Colorado. Data from 3 widely separated wells and in several zones per well all show a pressure increase during MHF treatments, called pressure growth. This pressure growth is at least semi-permanent. The elevated instantaneous shut-in pressures do not return to

W. L. Medlin; J. L. Fitch

1983-01-01

131

FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS  

EPA Science Inventory

Hydraulic fracturing, a method of increasing fluid flow within the subsurface, should improve the effectiveness of several remedial techniques, including pump and treat, vapor extraction, bio-remediation, and soil-flushing. he technique is widely used to increase the yields of oi...

132

Simple Strength Tests on and Hydraulic Fracturing of Rock Material.  

National Technical Information Service (NTIS)

Uniaxial compression, double shear and point load tests have been carried out with three rocks and used to estimate the Mohr failure envelopes. The results have been used to predict the hydraulic fracturing pressure for a bore hole in Bohus granite. Exper...

G. Wijk

1982-01-01

133

Municipalities and Hydraulic Fracturing: Trends in State Preemption  

Microsoft Academic Search

Hydraulic fracturing is a technology used to extract natural gas from shale rock formations found deep beneath the earth. It raises many public health and environmental issues of concern to municipalities and planners, both urban and rural. These issues range from potential water contamination and air pollution to noise, dust, truck traffic, and even minor earthquakes. This article identifies regulatory

Shaun A. Goho

2012-01-01

134

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

135

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...

136

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

137

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

138

Massive hydraulic fracture of Fenton Hill HDR Well EE-3  

SciTech Connect

Subsequent to a 5.6 million gallon massive hydraulic fracturing (MHF) experiment in Fenton Hill Hot Dry Rock (HDR) Well EE-2, a 2 million gallon MHF was planned for Well EE-3. Although hydraulic communication between wells EE-2 and EE-3 was not established during the initial MHF, a large reservoir was created around EE-2 which seemed to be in proximity with EE-3. The objective of this 2nd MHF was two-fold, to test the reservoir and seismic characteristics of the EE-3 openhole region from 11,390 to 11,770 ft and to drive fractures into the fractured region created earlier by the EE-2 MHF experiment. This paper discusses well repairs to prepare EE-3 for the MHF, the pumping operations, and injection parameters and briefly summarizes seismic results. 2 refs., 6 figs.

Dash, Z.V.; Dreesen, D.S.; Walter, F.; House, L.

1985-01-01

139

Fractal concept in numerical simulation of hydraulic fracturing of the hot dry rock geothermal reservoir  

Microsoft Academic Search

Hydraulic fracturing or hydraulic stimulation is one of the most effective methods of enhancing hot dry rock (HDR) geothermal system productivity. The 3D structure of the fractured rock is approximated by the network models of fractal geometry. The models of fracture networks are generated by distributing fractures randomly in space and assuming the fractal correlation Nr = Cr-D that incorporates

S. Fomin; T. Hashida; A. Shimizu; K. Matsuki; K. Sakaguchi

2003-01-01

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

Hydraulic fracturing method using delayed crosslinker composition  

Microsoft Academic Search

A method of fracturing a subterranean formation penetrated by a well, is described comprising: (a) producing a gel solution by adding to an aqueous solution of an organic crosslinkable carboxylated polymer: (i) a sufficient amount of a crosslinker composition to result in delayed crosslinking of the polymer, the cross-linker composition having an organic zirconium complex to crosslink the polymer, an

1988-01-01

142

Hydraulic fracturing method using delayed crosslinker composition  

Microsoft Academic Search

A method is described of fracturing a subterranean formation penetrated by a well, comprising: (a) producing a gel solution by adding to an aqueous solution of an organic carboxylated crosslinkable polymer: (i) a sufficient amount of a crosslinker composition to result in delayed crosslinking of the polymer. The crosslinker composition has an organic zirconium complex to crosslink the polymer, an

1987-01-01

143

A wet/wet differential pressure sensor for measuring vertical hydraulic gradient  

SciTech Connect

This article describes a new tool for measuring vertical hydraulic gradient in the hyporheic zone. It is essentially an electronic version of an established differential pressure measurement technique.

Fritz, Brad G.; Mackley, Rob D.

2008-12-13

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

MEASURING VERTICAL PROFILES OF HYDRAULIC CONDUCTIVITY WITH IN SITU DIRECT-PUSH METHODS  

EPA Science Inventory

U.S. EPA (Environmental Protection Agency) staff developed a field procedure to measure hydraulic conductivity using a direct-push system to obtain vertical profiles of hydraulic conductivity. Vertical profiles were obtained using an in situ field device-composed of a Geopr...

147

Using constant head step tests to determine hydraulic apertures in fractured rock  

Microsoft Academic Search

The initial step in the analysis of contaminant transport in fractured rock requires the consideration of groundwater velocity. Practical methods for estimating the average linear groundwater velocity (v¯) in fractured rock require determination of hydraulic apertures which are commonly calculated by applying the cubic law using transmissivity (T) values and the number of hydraulically active fractures in the test interval.

Patryk M. Quinn; Beth L. Parker; John A. Cherry

2011-01-01

148

Using constant head step tests to determine hydraulic apertures in fractured rock  

Microsoft Academic Search

The initial step in the analysis of contaminant transport in fractured rock requires the consideration of groundwater velocity. Practical methods for estimating the average linear groundwater velocity (v¯) in fractured rock require determination of hydraulic apertures which are commonly calculated by applying the cubic law using transmissivity (T) values and the number of hydraulically active fractures in the test interval.

Patryk M. Quinn; Beth L. Parker; John A. Cherry

149

Coupled Numerical Evaluations of the Geomechanical Interactions Between a Hydraulic Fracture Stimulation and a Natural Fracture System in Shale Formations  

NASA Astrophysics Data System (ADS)

Due to the low permeability of many shale reservoirs, multi-stage hydraulic fracturing in horizontal wells is used to increase the productive, stimulated reservoir volume. However, each created hydraulic fracture alters the stress field around it, and subsequent fractures are affected by the stress field from previous fractures. The results of a numerical evaluation of the effect of stress field changes (stress shadowing), as a function of natural fracture and geomechanical properties, are presented, including a detailed evaluation of natural fracture shear failure (and, by analogy, the generated microseismicity) due to a created hydraulic fracture. The numerical simulations were performed using continuum and discrete element modeling approaches in both mechanical-only and fully coupled, hydro-mechanical modes. The results show the critical impacts that the stress field changes from a created hydraulic fracture have on the shear of the natural fracture system, which in-turn, significantly affects the success of the hydraulic fracture stimulation. Furthermore, the results provide important insight into: the role of completion design (stage spacing) and operational parameters (rate, viscosity, etc.) on the possibility of enhancing the stimulation of the natural fracture network (`complexity'); the mechanisms that generate the microseismicity that occurs during a hydraulic fracture stimulation; and the interpretation of the generated microseismicity in relation to the volume of stimulated reservoir formation.

Nagel, N. B.; Sanchez-Nagel, M. A.; Zhang, F.; Garcia, X.; Lee, B.

2013-05-01

150

Hydraulic fracturing with a refractory proppant for sand control  

SciTech Connect

A sand control and heat transfer method is described for use in a borehole having an unconsolidated or loosely consolidated oil or gas reservoir which is otherwise likely to introduce substantial amounts of sand into the borehole, comprising: (a) providing a borehole casing through the reservoir; (b) perforating the casing at preselected intervals therealong to form at least one of longitudinal, in-line perforations; (c) hydraulically fracturing the reservoir by injecting a fracturing fluid containing a fine grain fused refractory material which comprises substantially silicon carbide or silicon nitride, and a clay stabilizing agent; (d) injecting a proppant comprising a gravel packing fused refractory material comprised substantially of silicon carbide or silicon nitride into the fracture, whereby a first layer of fine grain fused refractory material is held in place along the entire face of the fracture by a second layer of gravel packing fused refractory material also extending along the entire length of the fracture thereby excluding fines; and (e) producing oil or gas from the reservoir through the fracture into the borehole casing via a thermal oil recovery method which proppant and layers provide for increased heat transfer into the formation.

Jennings, A.R. Jr.; Stowe, L.R.

1989-04-04

151

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

152

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

153

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

154

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

155

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

156

Cold fluid hydraulic fracturing process for mineral bearing formations  

SciTech Connect

A method is described for hydraulically fracturing a subterranean formation region to stimulate the production of recoverable fluids comprising the steps of: providing a wellbore extending into the formation region and means for conducting fluid between the wellbore and the formation region; injecting a relatively cold liquid into the formation region through the wellbore at a rate which will result in substantial cooling of the formation region below the nominal preinjection temperature of the formation region so as to lower the stresses exerted within the formation region; increasing the pressure of the cold liquid being injected at a predetermined time after commencing injection of the cold liquid to a valve which will initiate a fracture in the cooled portion of the formation region; injecting a leakoff control agent with the cold liquid in sufficient amounts to provide further flooding of the formation region but to control the shape of the flood front progressing outward from the fracture; and injecting liquid into the fracture containing a quantity of proppant material for maintaining the fracture in a propped open condition upon release of pressure in the wellbore and the formation region due to the injected liquid.

Perkins, T.K.

1987-04-28

157

Rock Springs Site 12 Hydraulic/Explosive True in Situ Oil Shale Fracturing Experiment.  

National Technical Information Service (NTIS)

The experiment plan involved the creation and characterization of three horizontal hydraulic fractures, followed by the insertion and simultaneous detonation of slurry explosive in the two lower fractures. Core analyses, wellbore logging, and airflow and ...

R. L. Parrish R. R. Boade A. L. Stevens A. Long T. F. Turner

1980-01-01

158

Stimulation and Mineback Experiment Project. The Direct Observation of Hydraulic and Explosive Fracturing Tests.  

National Technical Information Service (NTIS)

Hydraulic and explosive fracturing experiments have been conducted adjacent to an existing tunnel complex at DOE's Nevada Test Site and have been directly observed by subsequent mineback through the experimental area. A proppant distribution fracture expe...

D. A. Northrop N. R. Warpinski R. A. Schmidt C. W. Smith

1978-01-01

159

Boundary element simulation of petroleum reservoirs with hydraulically fractured wells  

NASA Astrophysics Data System (ADS)

The boundary element method is applied to solve the linear pressure-diffusion equation of fluid-flow in porous media. The governing parabolic partial differential equation is transformed into the Laplace space to obtain the elliptic modified-Helmholtz equation including the homogeneous initial condition. The free- space Green's functions, satisfying this equation for anisotropic media in two and three dimensions, are combined with the generalized form of the Green's second identity. The resulting boundary integral equation is solved by following the collocation technique and applying the given time-dependent boundary conditions of the Dirichlet or Neumann type. The boundary integrals are approximated by the Gaussian quadrature along each element of the discretized domain boundary. Heterogeneous regions are represented by the sectionally-homogeneous zones of different rock and fluid properties. The final values of the interior pressure and velocity fields and of their time-derivatives are found by numerically inverting the solutions from the Laplace space by using the Stehfest's algorithm. The main extension of the mostly standard BEM-procedure is achieved in the modelling of the production and injection wells represented by internal sources and sinks. They are treated as part of the boundary by means of special single-node and both-sided elements, corresponding to the line and plane sources respectively. The wellbore skin and storage effects are considered for the line and cylindrical sources. Hydraulically fractured wells of infinite conductivity are handled directly according to the specified constraint type, out of the four alternatives. Fractures of finite conductivity are simulated by coupling the finite element model of their 1D-interior with the boundary element model of their 2D- exterior. Variable fracture width, fractures crossing zone boundaries, ``networking'' of fractures, fracture-tip singularity handling, or the 3D-description are additional advanced formulations of the proposed model of the hydraulically fractured wells. Another strong emphasis is put on the realization of the numerical model on a computer using the object-oriented programming. In addition to the graphical editor of input data, a higher-level language is designed to facilitate a universal data interface to the numerical simulator. The final version of the simulator is supplied on a CD-ROM together with the 35 solved example problems.

Pecher, Radek

160

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

161

Monitoring increases in fracture connectivity during hydraulic stimulations from temporal variations in shear wave splitting polarization  

NASA Astrophysics Data System (ADS)

Hydraulic overpressure can induce fractures and increase permeability in a range of geological settings, including volcanological, glacial and petroleum reservoirs. Here we consider an example of induced hydraulic fracture stimulation in a tight-gas sandstone. Successful exploitation of tight-gas reservoirs requires fracture networks, either naturally occurring, or generated through hydraulic stimulation. The study of seismic anisotropy provides a means to infer properties of fracture networks, such as the dominant orientation of fracture sets and fracture compliances. Shear wave splitting from microseismic data acquired during hydraulic fracture stimulation allows us to not only estimate anisotropy and fracture properties, but also to monitor their evolution through time. Here, we analyse shear wave splitting using microseismic events recorded during a multistage hydraulic fracture stimulation in a tight-gas sandstone reservoir. A substantial rotation in the dominant fast polarization direction (?) is observed between the events of stage 1 and those from later stages. Although large changes in ? have often been linked to stress-induced changes in crack orientation, here we argue that it can better be explained by a smaller fracture rotation coupled with an increase in the ratio of normal to tangential compliance (ZN/ZT) from 0.3 to 0.6. ZN/ZT is sensitive to elements of the internal architecture of the fracture, as well as fracture connectivity and permeability. Thus, monitoring ZN/ZT with shear wave splitting can potentially allow us to remotely detect changes in permeability caused by hydraulic stimulation in a range of geological settings.

Baird, Alan F.; Kendall, J.-Michael; Verdon, James P.; Wuestefeld, Andreas; Noble, Todd E.; Li, Yongyi; Dutko, Martin; Fisher, Quentin J.

2013-08-01

162

Monitoring increases in fracture connectivity during hydraulic stimulations from temporal variations in shear wave splitting polarization  

NASA Astrophysics Data System (ADS)

Hydraulic overpressure can induce fractures and increase permeability in a range of geological settings, including volcanological, glacial and petroleum reservoirs. Here we consider an example of induced hydraulic fracture stimulation in a tight-gas sandstone. Successful exploitation of tight-gas reservoirs requires fracture networks, either naturally occurring, or generated through hydraulic stimulation. The study of seismic anisotropy provides a means to infer properties of fracture networks, such as the dominant orientation of fracture sets and fracture compliances. Shear wave splitting from microseismic data acquired during hydraulic fracture stimulation allows us to not only estimate anisotropy and fracture properties, but also to monitor their evolution through time. Here, we analyse shear wave splitting using microseismic events recorded during a multistage hydraulic fracture stimulation in a tight-gas sandstone reservoir. A substantial rotation in the dominant fast polarization direction (?) is observed between the events of stage 1 and those from later stages. Although large changes in ? have often been linked to stress-induced changes in crack orientation, here we argue that it can better be explained by a smaller fracture rotation coupled with an increase in the ratio of normal to tangential compliance (ZN/ZT) from 0.3 to 0.6. ZN/ZT is sensitive to elements of the internal architecture of the fracture, as well as fracture connectivity and permeability. Thus, monitoring ZN/ZT with shear wave splitting can potentially allow us to remotely detect changes in permeability caused by hydraulic stimulation in a range of geological settings.

Baird, Alan F.; Kendall, J.-Michael; Verdon, James P.; Wuestefeld, Andreas; Noble, Todd E.; Li, Yongyi; Dutko, Martin; Fisher, Quentin J.

2013-11-01

163

Pressure-gradient singularity and production enhancement for hydraulically fractured wells  

NASA Astrophysics Data System (ADS)

When a hydraulic fracture is modelled as a slit, the flow of the reservoir fluid towards the fracture develops a pressure-gradient singularity at the sharp fracture tips for both steady and transient flows. This pressure-gradient singularity also creates a flux-density singularity of the same type at the fracture tips. We study this pressure-gradient/flux singularity and its role in the production enhancement for hydraulically fractured wells in detail for the stabilized flow regime. Analytical solutions for slit, rectangular and elliptical shape fractures in the limit of infinite dimensionless fracture conductivity are used to analyse the flow physics. Our analyses reveal the exact mathematical nature of the pressure-gradient tip singularity and its regularization by the elliptical geometry. We show that this pressure-gradient tip singularity causes the flow from the region ahead of the fracture tip to converge and focus at the fracture tip. This flow pattern concentrates the production to the region near the fracture tip and increases the flux along the entire fracture surface. The singularity in the reservoir pressure-gradient is inherent for all fractures with sharp ends in both steady and transient flows regardless of the fracture conductivity. Our results establish pressure-gradient tip singularity as a universal and primary mechanism for enhanced productivity from hydraulically fractured wells. The large suction forces at the fracture tips induce the fluid to flow from an ultra-low permeability reservoir into a hydraulic fracture.

Chen, Kang Ping; Jin, Yan; Chen, Mian

2013-11-01

164

Techniques for quantifying formation stress and fracture fluid response for optimum hydraulic fracture design  

SciTech Connect

Improved fracturing treatment design has been achieved by computerised interpretation of the mechanical properties logs, laboratory rock properties measurements and production logging during minifrac tests. By combining these data acquisition techniques in a single well, optimum hydraulic fracturing design input information is obtained. These techniques have been successfully used in a Southern Sector North Sea well. Subsequently, real-time and post-treatment evaluations have indicated the reliability of the technique. Actual field data are presented showing use of these data. Also presented is a computer generated fracture geometry processed from mechanical properties log data. Due to the importance of accurate fracture geometry prediction in current North Sea gas field development, the techniques have proven to be a valuable aid.

Frisinger, M.; Cooper, R.E.

1985-01-01

165

Hydraulic tomography in fractured granite: Mizunami Underground Research site, Japan  

NASA Astrophysics Data System (ADS)

Two large-scale cross-hole pumping tests were conducted at depths of 191-226 m and 662-706 m in deep boreholes at the Mizunami Underground Research Laboratory (MIU) construction site in central Japan. During these two tests, induced groundwater responses were monitored at many observation intervals at various depths in different boreholes at the site. We analyze the two cross-hole pumping tests using transient hydraulic tomography (THT) based on an efficient sequential successive linear estimator to compute the hydraulic conductivity (K) and specific storage (Ss) tomograms, as well as their uncertainties in three dimensions. The equivalent K and Ss estimates obtained using asymptotic analysis treating the medium to be homogeneous served as the mean parameter estimates for the 3-D stochastic inverse modeling effort. Results show several, distinct, high K and low Ss zones that are continuous over hundreds of meters, which appear to delineate fault zones and their connectivity. The THT analysis of the tests also identified a low K zone which corresponds with a known fault zone trending NNW and has been found to compartmentalize groundwater flow at the site. These results corroborate well with observed water level records, available fault information, and coseismic groundwater level responses during several large earthquakes. The successful application of THT to cross-hole pumping tests conducted in fractured granite at this site suggests that THT is a promising approach to delineate large-scale K and Ss heterogeneities, fracture connectivity, and to quantify uncertainty of the estimated fields.

Illman, Walter A.; Liu, Xiaoyi; Takeuchi, Shinji; Yeh, Tian-Chyi Jim; Ando, Kenichi; Saegusa, Hiromitsu

2009-01-01

166

Hemisection as an alternative treatment for vertically fractured mandibular molars.  

PubMed

Hemisection of mandibular molars may be a viable treatment option when vertical root fracture has occurred and the other root is healthy. This article discusses a case that presents the techniques involved in hemisection and restoration of the remaining tooth root. PMID:16494100

Kurtzman, Gregori M; Silverstein, Lee H; Shatz, Peter C

2006-02-01

167

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

Microsoft Academic Search

The long radius, near-horizontal well has been drilled and completion operations are in progress. Upon initial review of log data, two hydraulic fracture treatments were planned. However, the probability of the lower frac growing into thick sands previously swept by waterflood has called for additional information to be obtained prior to proceeding with hydraulic fracture treatments. Should permeabilities prove to

Laue

1997-01-01

168

LIMITING DRILLING SLURRY PRESSURES TO CONTROL HYDRAULIC FRACTURING DURING HDD THROUGH PURELY COHESIVE SOIL  

Microsoft Academic Search

Hydraulic fracturing is a problem associated with Horizontal Directional Drilling that is still inadequately understood and can result in serious consequences. During insertion of utility conduits and other buried pipe infrastructure, drilling slurry is used to stabilize the soil around the excavation zone prior to pulling the new pipeline into place. Hydraulic fracturing occurs when the drilling slurry flows through

Matthew J. Kennedy; Graeme D. Skinner; Ian D. Moore

169

Directional dependency of hydraulic conductivity in rock masses with multiple fracture sets  

Microsoft Academic Search

Within a fractured rock mass, the hydraulic conductivity is dependent upon spacing, aperture, orientation, connectivity, and surface roughness of the fracture, and the permeability of the unfractured medium. The directional dependence of hydraulic conductivity was examined and modeled based on a variation of the Cubic Law for both two and three dimensional systems. In these models, the spacing, aperture, connectivity,

Masterlark

1994-01-01

170

Mapping acoustic emissions from hydraulic fracture treatments using coherent array processing: Concept.  

National Technical Information Service (NTIS)

Hydraulic fracturing is a widely-used well completion technique for enhancing the recovery of gas and oil in low-permeability formations. Hydraulic fracturing consists of pumping fluids into a well under high pressure (1000--5000 psi) to wedge-open and ex...

D. B. Harris P. E. Harben R. J. Sherwood S. P. Jarpe

1991-01-01

171

Development of a generalized hydraulic fracture model. Annual report, November 1, 1983October 31, 1984  

Microsoft Academic Search

The reported investigations furnish an integrated framework for hydraulic fracture model development. The finite element code for the determination of formation principal stresses provides a capability for in situ stress evaluation based on measured field data. The exact solutions for specialized cases associated with hydraulic fracturing are invaluable in terms of code validation, parametric sensitivity studies, and assumption verification. The

S. H. Advani; J. K. Lee

1984-01-01

172

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...

173

78 FR 34611 - Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands  

Federal Register 2010, 2011, 2012, 2013

...WO-300-L13100000.FJ0000] RIN 1004-AE26 Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands AGENCY: Bureau of...the Federal Register a proposed rule to regulate hydraulic fracturing on Federal and Indian land. Due to the...

2013-06-10

174

Propagation of a hydraulic fracture parallel to a free surface  

NASA Astrophysics Data System (ADS)

This paper analyses the plane strain problem of a fracture, driven by injection of an incompressible viscous Newtonian fluid, which propagates parallel to the free surface of an elastic half-plane. The problem is governed by a hyper-singular integral equation, which relates crack opening to net pressure according to elasticity, and by the lubrication equations which describe the laminar fluid flow inside the fracture. The challenge in solving this problem results from the changing nature of the elasticity operator with growth of the fracture, and from the existence of a lag zone of a priori unknown length between the crack tip and the fluid front. Scaling of the governing equations indicates that the evolution problem depends in general on two numbers, one which can be interpreted as a dimensionless toughness and the other as a dimensionless confining stress. The numerical method adopted to solve this non-linear evolution problem combines the displacement discontinuity method and a finite difference scheme on a fixed grid, together with a technique to track both crack and fluid fronts. It is shown that the solution evolves in time between two asymptotic similarity solutions. The small time asymptotic solution corresponding to the solution of a hydraulic fracture in an infinite medium under zero confining stress, and the large time to a solution where the aperture of the fracture is similar to the transverse deflection of a beam clamped at both ends and subjected to a uniformly distributed load. It is shown that the size of the lag decreases (to eventually vanish) with increasing toughness and compressive confining stress. Copyright

Zhang, X.; Jeffrey, R. G.; Detournay, E.

2005-11-01

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

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

177

CO2 laser irradiation on vertical root fracture  

NASA Astrophysics Data System (ADS)

Vertical root fracture has been requested tooth extraction or root hemisection. There is no conservative treatment. The purpose of this paper was to analyze the CO2 laser effects on root fracture, associated with other materials. Forty two extracted human canines divided into 6 groups have their root vertically fractured. In groups A and B the CO2 laser was used with power of 5 W and 7 W respectively and the fracture line was covered with glass ionomer cement. In groups C and D the laser was used with 5 and 7 W and fracture line was covered with a dual composite. Groups E and F were controls, treated with glass ionomer cement and FLC dual composite. The teeth were placed in 5 percent methylene blue dye for 48 hs. The dye penetration was lowest in groups with glass ionomer cement and laser (A and B), at about (1.06mm). The difference between groups was statistically significant at 1 percent. All experimental groups showed dye penetration. The laser seemed to favor the sealing of the fracture line.

da Silva, Luciana X.; Aun, Carlos E.; de Campos Ferraz, Jussara

1997-05-01

178

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

179

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

180

Hydraulic Characteristics of Rough Fractures in Linear Flow under Normal and Shear Load  

Microsoft Academic Search

Summary  \\u000a A hydro-mechanical testing system, which is capable of measuring both the flow rates and the normal and shear displacement\\u000a of a rock fracture, was built to investigate the hydraulic behaviour of rough tension fractures. Laboratory hydraulic tests\\u000a in linear flow were conducted on rough rock fractures, artificially created using a splitter under various normal and shear\\u000a loading. Prior to

H. S. Lee; T. F. Cho

2002-01-01

181

Multiple vertical fractures from an inclined wellbore--a field experiment  

Microsoft Academic Search

A procedure is described in which multiple, vertical fractures are created from a single, directionally drilled well bore. The purpose is to increase fracture area over what can be achieved from a single vertical fracture initiated from a conventional vertical well bore. This will provide for more rapid and efficient drainage of a specific reservoir volume. A field experiment to

M. K. Strubhar; J. L. Fitch; E. E. Jr. Glenn

1974-01-01

182

Evaluation of vertical permeability anisotropy in fractured reservoirs  

SciTech Connect

In fractured reservoir flow simulations, the vertical permeability anisotropy ratio (Kv/Kh) is one of the most poorly defined input parameters. In the best cases, this ratio is obtained from well-test interpretation with partial penetration models. More generally, it is considered as a parameter that can be varied to allow matching of actual data in flow simulations. However it is obtained, extrapolation of the anisotropy ratio away from the well is difficult due to the lack of geological basis in its estimation. A more rigorous association with the fracture descriptions and structural controls is clearly required. This study presents a new approach based on stochastic fracture generation (Boolean technique) combined with upscaling techniques to calculate permeability tensors at different scales. Several geological cases are tested ([open quotes]homogeneous[close quotes] or layered reservoir) as well as the influence of many parameters: fracture form index, fracture width, and matrix permeability. For each case, the influence of fracture density is evaluated; typical curves, anisotropy ratios vs. density of fractures, are obtained, whose general form is the same, thereby allowing comparisons to be made.

Massonnat, G.J. (Elf Aquitaine, Pau (France)); Manisse, E. (Institut Physique du Globe, Strasbourg (France))

1994-07-01

183

Directional dependency of hydraulic conductivity in rock masses with multiple fracture sets  

SciTech Connect

Within a fractured rock mass, the hydraulic conductivity is dependent upon spacing, aperture, orientation, connectivity, and surface roughness of the fracture, and the permeability of the unfractured medium. The directional dependence of hydraulic conductivity was examined and modeled based on a variation of the Cubic Law for both two and three dimensional systems. In these models, the spacing, aperture, connectivity, surface roughness, and permeability of the surrounding medium were held constant. The hydraulic conductivity for two intersecting fracture sets was plotted using a polar coordinate system. The resulting figure resembles two superposed ellipsoids with mutually perpendicular major axes. For two intersecting fracture systems, there are two absolute maxima, two relative maxima, and four minima in hydraulic conductivity. For systems with more than two fracture sets, relative maxima occur in directions parallel to the bisectors of intersecting fracture sets. Relative minima occur in directions perpendicular to a fracture set. Investigations of a three dimensional system reveal a similar relationship between hydraulic conductivity and fracture orientations. The authors have also conducted a harmonic analysis to study the relationship between the orientations of multiple fracture sets and hydraulic conductivity.

Masterlark, T.L. (Univ. of Wisconsin, Eau Claire, WI (United States). Geology Dept.)

1994-04-01

184

Experimental study on hydraulic fracturing of soft rocks: Influence of fluid rheology and confining stress  

Microsoft Academic Search

This paper presents an experimental study on hydraulic fracturing of unconsolidated rocks focusing on mechanisms of fracture initiation and propagation using different injection fluids at various confining stresses. Thus, a serial of parameter study including confining stress, type of injection fluid and geometry of injection section was carried out to explore the dependency of fracturing on these variables. Results showed

B. Bohloli; C. J. de Pater

2006-01-01

185

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

186

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

187

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

188

Scattering by hydraulic fractures: Finite-difference modeling and laboratory data  

Microsoft Academic Search

Reservoir production can be stimulated by creating hydraulic fractures that effectively facilitate the inflow of hydrocarbons into a well. Considering the effectiveness and safety of the operation, it is desirable to monitor the size and location of the fracture. In this paper, the authors investigate the possibilities of using seismic waves generated by active sources to characterize the fractures. First,

Jeroen Groenenboom; Joachim Falk

2000-01-01

189

The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)  

NASA Astrophysics Data System (ADS)

Fracture network connectivity is a spatially variable property that is difficult to quantify from standard hydrogeological datasets. This critical property is related to the distributions of fracture density, orientation, dimensions, intersections, apertures and roughness. These features that determine the inherent connectivity of a fracture network can be modified by secondary processes including weathering, uplift and unloading and other mechanisms that lead to fracture deformation in response to in situ stress. This study focussed on a fractured rock aquifer in the Clare Valley, South Australia, and found that fracture network connectivity could be discriminated from several geological, geophysical and hydrogeological field datasets at various scales including single well and local- to regional-scale data. Representative hydromechanical models of the field site were not only consistent with field observations but also highlighted the strong influence of in situ stress in determining the distribution of fracture hydraulic apertures and the formation of hydraulic chokes that impede fluid flow. The results of this multi-disciplinary investigation support the notion that the hydraulic conductivity of a fracture network is limited to the least hydraulically conductive interconnected fractures, which imposes a physical limit on the bulk hydraulic conductivity of a fractured rock aquifer.

Mortimer, Luke; Aydin, Adnan; Simmons, Craig T.; Heinson, Graham; Love, Andrew J.

2011-11-01

190

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

191

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

192

Laboratory imaging of stimulation fluid displacement from hydraulic fractures  

SciTech Connect

Laboratory experiments were conducted to physically investigate the processes governing stimulation fluid displacement from hydraulic fractures. Experiments were performed on two scales: meter-scale in a 1500 cm{sup 2} sand pack and core-scale in a 65 cm{sup 2} API linear conductivity cell. High-resolution light transmission imaging was employed at the meter-scale to visualize and quantify processes governing fluid displacement. For comparison, complimentary tests were performed using an API conductivity cell under ambient test conditions and at elevated closure stress. In these experiments viscous fingering and gravity drainage were identified as the dominant processes governing fluid displacement. Fluid viscosity was found to dictate the relative importance of the competing displacement processes and ultimately determine the residual liquid saturation of the sand pack. The process by which fluid displacement occurs was seen to effect the shape of both the gas and liquid phase relative permeability functions. Knowledge of such viscosity/relative permeability relationships may prove useful in bounding predictions of post-stimulation recovery of gels from the fracture pack.

Tidwell, V. [Sandia National Lab., Albuquerque, NM (United States); Parker, M. [SPE, Richardson, TX (United States)

1996-11-01

193

Fracture mechanics analysis of vertical root fracture from condensation of gutta-percha.  

PubMed

A two-dimensional fracture mechanics analysis of vertical root fracture (VRF) in single-canal roots from apical condensation of gutta-percha (gp) is developed. The resulting analytic relation for apical load causing VRF agrees with major trends reported in in-vitro tests on roots subjected to either continuous or, the more clinically relevant, repeating vertical condensation of gp. The model explicitly exposes the role of root canal morphology and dentin fracture toughness on VRF. Ovoid and irregular canals are prone to fracture while the effect of mean root canal radius is modest. Canal taper and instrumentation details may affect VRF only marginally and indirectly. The model predicts dentinal cracks to occur following root canal instrumentation and obturation, which may pose long-term threats to tooth integrity. PMID:22503579

Chai, Herzl; Tamse, Aviad

2012-04-13

194

The EPA's Study on the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources  

NASA Astrophysics Data System (ADS)

Natural gas plays a key role in our nation's clean energy future. The United States has vast reserves of natural gas that are commercially viable as a result of advances in horizontal drilling and hydraulic fracturing technologies, which enable greater access to gas in rock formations deep underground. These advances have spurred a significant increase in the production of both natural gas and oil across the country. However, as the use of hydraulic fracturing has increased, so have concerns about its potential human health and environmental impacts, especially for drinking water. In response to public concern, the US Congress requested that the US Environmental Protection Agency (EPA) conduct scientific research to examine the relationship between hydraulic fracturing and drinking water resources. In 2011, the EPA began research to assess the potential impacts of hydraulic fracturing on drinking water resources, if any, and to identify the driving factors that may affect the severity and frequency of such impacts. The study is organized around the five stages of the hydraulic fracturing water cycle, from water acquisition through the mixing of chemicals and the injection of fracturing fluid to post-fracturing treatment and/or disposal of wastewater. EPA scientists are using a transdisciplinary research approach involving laboratory studies, computer modeling, toxicity assessments, and case studies to answer research questions associated with each stage of the water cycle. This talk will provide an overview of the EPA's study, including a description of the hydraulic fracturing water cycle and a summary of the ongoing research projects.

Burden, Susan

2013-03-01

195

Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, October 1--December 31, 1997  

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 is used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments are determined, in part, by fracturing an existing test well. Fracture azimuth is 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 has been drilled. Swept-out sand intervals and a poor cement bond behind the 5 in. liner precluded two of the three originally planned hydraulic fracture treatments. All pay intervals behind the 5 in. liner were therefore 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 then perforated. The well was returned to production to observe production trends and pressure behavior prior to stimulation of the newer perforations.

Laue, M.L.

1998-02-05

196

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

197

Understanding Hydraulic Fracture Stimulations in Oil-Gas Developments Using Microseismicity (M<0)  

NASA Astrophysics Data System (ADS)

Microseismic monitoring is widely recognized as a powerful production optimization tool in the oil and gas industry. In particular, microseismic imaging has been shown to provide insight into the dynamic behavior of reservoirs during hydraulic fracture stimulations. In this presentation, we explore ideas and provide examples of preliminary work linking microseismicity, geology and engineering to build predictive reservoir models and to assist with their calibration and validation. Generally, microseismic imaging of hydraulic fractures focuses on mapping event locations. By simply examining the spatial and temporal variations in microseismicity, overall geometric measures such as orientation, fracture extent (height, length, and width) and fracture growth can be assessed. Examining fracture growth in the context of traditional hydraulic fracture models, estimates of fracture geometry based on microseismic data have been used to support the accepted fracture behavior. In hydraulic fracture stimulations, fractures are generally considered to develop along a single fracture azimuth or along a plane of fracturing controlled by regional stresses (i.e. along the direction of maximum principle stress), even within the context of a three-dimensional fracture network. In this study, we show how seismic moment tensors and source parameters have been used to assess the orientation of newly formed or reactivated fractures, as well as evaluate their size or time-dependent response to fluid injections. As well, using nearest-neighbor statistics, events can be grouped into behavioral domains, such as near-treatment-well and fracture extension regions, and used to outline a Discrete Fracture Network (DFN). Evaluating the spatial-temporal development of the DFN within the defined volumes can then be used to assess the fracture connectivity and enhanced permeability associated with the treatment. With moment tensor analysis, we show how petroleum engineers can also assess the effectiveness of different stimulation programs, and define the "effective fracture zone" associated with the stimulation. Knowledge of the effective fracture zone can then be used to estimate the Stimulated Reservoir Area (SRA) or Volume (SRV) associated with the treatment program and enable enhanced calculations of productivity. Using Hudson plots, changes in fracture behaviour from an opening dominated, fracture-extension regime to an ineffective closure-dominant regime, can identify Points of Diminishing Returns (PDR) as temporal points where continued stimulation of the reservoir with the same pumping regime will no longer extend the fracture network. Understanding when a fracture stage reaches a PDR enables engineers to adjust treatment plans to re-initiate fracture extension, achieve better proppant distribution or design future fracture networks to realize higher conductivity. This ability to integrate microseismic analysis with knowledge of the fracture treatment program serves as an invaluable tool for engineers who are trying to design and perform optimal fracture stimulations.

Urbancic, T.; Baig, A. M.

2011-12-01

198

Using constant head step tests to determine hydraulic apertures in fractured rock.  

PubMed

The initial step in the analysis of contaminant transport in fractured rock requires the consideration of groundwater velocity. Practical methods for estimating the average linear groundwater velocity (v¯) in fractured rock require determination of hydraulic apertures which are commonly calculated by applying the cubic law using transmissivity (T) values and the number of hydraulically active fractures in the test interval. High-resolution, constant-head step injection testing of cored boreholes in a 100 m thick fractured dolostone aquifer was conducted using inflatable packers to isolate specific test intervals from the rest of the borehole. The steps in each test interval were gradually increased from very low to much higher injection rates. At smaller injection rates, the flow rate vs. applied pressure graph projects through the origin and indicates Darcian flow; non Darcian flow is evident at higher injection rates. Non-Darcian flow results in significantly lower calculated T values, which translates to smaller hydraulic aperture values. Further error in the calculated hydraulic aperture stems from uncertainty in the number of hydraulically active fractures in each test interval. This estimate can be inferred from borehole image and core logs, however, all of the fractures identified are not necessarily hydraulically active. This study proposes a method based on Reynolds number calculations aimed at improving confidence in the selection of the number of active fractures in each test interval. PMID:21885152

Quinn, Patryk M; Parker, Beth L; Cherry, John A

2011-07-27

199

Variability of streambed vertical hydraulic conductivity with depth along the Elkhorn River, Nebraska, USA  

Microsoft Academic Search

Determination of streambed hydraulic conductivity is of great importance in the analysis of stream-aquifer interactions and\\u000a stream ecosystems. In this paper, in situ falling-head standpipe permeameter tests were conducted to determine streambed vertical hydraulic conductivity (K\\u000a \\u000a v\\u000a ) of two connected layers of sediments at 60 test locations from eight sites in the Elkhorn River, Nebraska. Our results show\\u000a that

JinXi Song; XunHong Chen; Cheng Cheng; DeMing Wang; WenKe Wang

2010-01-01

200

Massive Hydraulic Fracturing Experiments of the Devonian Shale in Lincoln County, West Virginia.  

National Technical Information Service (NTIS)

The following preliminary conclusions were reached: Shale Stimulation Treatments - Hydraulically fractured wells will produce considerably more gas than wells stimulated with 80% gelled nitroglycerine. From a cost standpoint, the results suggest a single ...

S. P. Cremean R. M. Forrest S. F. McKetta W. F. Morse G. L. Owens

1979-01-01

201

Hydraulic Fracture Diagnostics Research. Part 2. Research Results. Annual Report July 1983-June 1984.  

National Technical Information Service (NTIS)

The paper describes the design, deployment and operation of an extensive seismic network for detecting and recording signals and noise related to the growth of hydraulically induced fracture system in a sand formation at an approximate 1000-foot depth. Th...

B. C. Kimball C. C. Mulcahy F. J. Mauk J. C. Cook T. M. C. Li

1984-01-01

202

Evaluation of Washington Hydraulic Fracture Test (SHRP) for D-Cracking Aggregate.  

National Technical Information Service (NTIS)

An evaluation was funded by the Illinois Department of Transportation (ILDOT) to investigate the ability of the Washington Hydraulic Fracture Test to identify D-cracking susceptible aggregate. Two machines were used for testing: the large (WHFT 97) which ...

M. A. Issa M. A. Issa M. Bendok

1999-01-01

203

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

National Technical Information Service (NTIS)

Natural gas plays a key role in our nation's clean energy future. Recent advances in drilling technologies including horizontal drilling and hydraulic fracturing have made vast reserves of natural gas economically recoverable in the US. Responsible develo...

2011-01-01

204

Hydraulic Fracturing of Drilled Water Wells in Crystalline Rocks of New Hampshire.  

National Technical Information Service (NTIS)

During May 1973, hydraulic fracturing methods were used successfully to stimulate the yield of two drilled water wells in crystalline rocks at the Horticultural Farm, University of New Hampshire. This method attempts to reduce the risk of recovering an ad...

G. W. Stewart

1978-01-01

205

Use of temperature profiles beneath streams to determine rates of vertical ground-water flow and vertical hydraulic conductivity  

USGS Publications Warehouse

The use of temperature profiles beneath streams to determine rates of vertical ground-water flow and effective vertical hydraulic conductivity of sediments was evaluated at three field sites by use of a model that numerically solves the partial differential equation governing simultaneous vertical flow of fluid and heat in the Earth. The field sites are located in Hardwick and New Braintree, Mass., and in Dover, N.J. In New England, stream temperature varies from about 0 to 25 ?C (degrees Celsius) during the year. This stream-temperature fluctuation causes ground-water temperatures beneath streams to fluctuate by more than 0.1 ?C during a year to a depth of about 35 ft (feet) in fine-grained sediments and to a depth of about 50 ft in coarse-grained sediments, if ground-water velocity is 0 ft/d (foot per day). Upward flow decreases the depth affected by stream-temperature fluctuation, and downward flow increases the depth. At the site in Hardwick, Mass., ground-water flow was upward at a rate of less than 0.01 ft/d. The maximum effective vertical hydraulic conductivity of the sediments underlying this site is 0.1 ft/d. Ground-water velocities determined at three locations at the site in New Braintree, Mass., where ground water discharges naturally from the underlying aquifer to the Ware River, ranged from 0.10 to 0.20 ft/d upward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.4 to 17.1 ft/d. Ground-water velocities determined at three locations at the Dover, N.J., site, where infiltration from the Rockaway River into the underlying sediments occurs because of pumping, were 1.5 ft/d downward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.2 to 2.5 ft/d. Independent estimates of velocity at two of the three sites are in general agreement with the velocities determined using temperature profiles. The estimates of velocities and conductivities derived from the temperature measurements generally fall within the ranges of expected rates of flow in, and conductivities of, the sediments encountered at the test sites. Application of the method at the three test sites demonstrates the feasibility of using the method to determine the rate of ground-water flow between a stream and underlying sediments and the effective vertical hydraulic conductivity of the sediments.

Lapham, Wayne W.

1989-01-01

206

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

Microsoft Academic Search

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

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

2000-01-01

207

Rock Springs Site 12 hydraulic/explosive true in situ oil shale fracturing experiment  

SciTech Connect

The experiment plan involved the creation and characterization of three horizontal hydraulic fractures, followed by the insertion and simultaneous detonation of slurry explosive in the two lower fractures. Core analyses, wellbore logging, and airflow and /sup 85/Kr tracer tests were used for site characterization and assessment of the hydraulic and explosive fracturing. Tiltmeters, wellhead pressure and flow gages, and in-formation pressure, flow and crack-opening sensors were used to monitor hydrofracture creation and explosive insertion. Explosive detonation diagnostic data were taken with stress and time-of-arrival gages and surface and in-formation accelerometers. The post-fracturing assessments indicated that: (1) hydrofracture creation and explosive insertion and detonation were accomplished essentially as planned; (2) induced fractures were randomly distributed through the shale with no extensively fractured regions or dislocation of shale; and (3) enhancement of permeability was limited to enlargement of the explosive-filled fractures.

Parrish, R.L.; Boade, R.R.; Stevens, A.L.; Long, A. Jr.; Turner, T.F.

1980-06-01

208

Does hydraulic-fracturing theory work in jointed rock masses  

Microsoft Academic Search

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

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

1983-01-01

209

Hydraulic conductivity of partially saturated fractured porous media: flow in a cross-section  

Microsoft Academic Search

Standard models for hydraulic functions of partially saturated fractured porous media (FPM) often rely on macroscopic continuum representation and embrace constitutive relationships originally developed for homogeneous porous media to describe hydraulic behavior of dual (or multi) continua FPM. Such approaches lead to inconsistencies due to neglect of underlying physical processes governing liquid retention and flow in the vastly different pore

Dani; Markus Tuller

2003-01-01

210

Method for hydraulic fracture propagation in hydrocarbon-bearing formations  

SciTech Connect

A method is described of hydraulically fracturing a hydrocarbon-bearing strata in a hydrocarbon producing well comprising: providing a hydrocarbon-producing well having a hydrocarbon-bearing strata, a bounding non-producing strata overlying the hydrocarbon-bearing strata, and a bounding non-producing strata underlying the hydrocarbon-producing strata; determining the maximum principal compressive stress S/sub 1/ for the hydrocarbon-bearing strata, the overlying bounding non-producing strata, and the underlying bounding non-producing strata; determining the pore fluid pressure P/sub F/ for the hydrocarbon-bearing strata, the overlying bounding non-producing strata, and the underlying bounding non-producing strata; determining the coefficient of friction u for the hydrocarbon-bearing strata, the overlying bounding non-producing strata, and the underlying bounding non-producing strata; determining the least principal compressive stress S/sub 3/ for the hydrocarbon-bearing strata, the overlying bounding non-producing strata, and the underlying bounding non-producing strata.

Zoback, M.D.; Raleigh, C.B.

1987-01-13

211

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

212

Computer modeling of SCC in gas pipe steel and hydraulic fracture in stratified poro-elastic media  

Microsoft Academic Search

The main topic of this thesis is the modeling of fracture of steel pipes and stratified rocks. The study of fracture of steel pipes suggests a way to protect materials from a premature failure. On the other hand, the study of fracture of stratified rocks helps to find a way to optimize hydraulic fractures. Firstly, the fracturing process that happened

Juncai Fan

2001-01-01

213

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

214

Parameter equivalence for the Gardner and van Genuchten soil hydraulic conductivity functions for steady vertical flow with inclusions  

Microsoft Academic Search

The analytic element method is well suited for the Gardner hydraulic conductivity function, but is limited in describing real soils. Therefore, parameter equivalence between the van Genuchten and Gardner hydraulic conductivity functions is explored for the case of steady vertical flow through a homogeneous medium with a single inclusion, i.e., a binary soil. The inclusion has different hydraulic parameters than

Dale F. Rucker; Arthur W. Warrick; Ty P. A. Ferreb

2005-01-01

215

Preliminary Assessment of a Hot Dry Rock Geothermal Energy Reservoir Formed by Hydraulic Fracturing  

Microsoft Academic Search

If a mass of relatively impermeable hot rock can be hydraulically fractured and if a heat extraction fluid can be circulated through the fracture and recovered, appreciable amounts of energy can be extracted from the rock. The Los Alamos Hot Dry Rock Geothermal Energy Project is designed to investigate and demonstrate this concept. A series of field experiments have been

Hugh D. Murphy; Robert G. Lawton; Jefferson W. Tester; Robert M.. Brown; Donald W; R. Lee Aamodt

1976-01-01

216

Stress wave propagationin the site 12 hydraulic\\/explosive fracturing experiment  

Microsoft Academic Search

The Site 12 experiment was a heavily instrumented field event performed to examine the hydraulic\\/explosive fracturing concept for preparing an underground oil shale bed for true in situ processing. One of the key phases of this fracturing concept is the blasting operation which involves the insertion and detonation of slurry explosive in a pre-formed system of hydrofractures. To obtain a

R. R. Boade; R. P. Reed

1980-01-01

217

Demonstration of massive hydraulic fracturing: Piceance Basin, Rio Blanco County, Colorado  

Microsoft Academic Search

A massive hydraulic fracturing demonstration has been conducted by Mobil and DOE in Mesaverde and overlying sands below the productive Wasatch Formation in Mobil's Piceance Creek Field. The experimental well was drilled in 1977. During that year intervals between 9500 and 10,800 ft. were tested and massive fracturing treatments were carried out in two of them, zones 1 and 3.

J. L. Fitch; W. L. Medlin; M. K. Strubhar

1979-01-01

218

New Method for Determining Dominant Fluid Flow Paths During Hydraulic Fracturing.  

National Technical Information Service (NTIS)

Although hydraulic fracturing is a method that has been applied for many years to increase fracture permeability of reservoirs, there is no direct way other than drilling additional boreholes to determine where the injected fluid has gone and thus what di...

M. Fehler

1987-01-01

219

Using radar tomography, tracer experiments and hydraulic data to characterize fractured rock flow systems  

Microsoft Academic Search

Among the most pressing problems in hydrogeology is describing heterogeneity in fractured rock, where data are typically local and sparse, and permeability varies by orders of magnitude over short distances. This dissertation presents new approaches to characterize fractured rock groundwater flow systems using cross-well radar, tracer, and hydraulic experiments. The methods are demonstrated using data from the U.S. Geological Survey

Frederick David Day-Lewis

2001-01-01

220

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

221

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

222

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

223

Relation of formation rock strength to propping agent strength in hydraulic fracturing  

Microsoft Academic Search

Theoretical and laboratory data presented should be useful in decreasing the amount of laboratory work necessary in selecting a rigid propping agent for hydraulic fracturing. Tests (with steel plates) may be made to obtain the loading strengths of the various rigid propping materials. When a core sample from a zone to be fractured is received, a penetrometer test on a

B. B. McGlothlin; J. L. Huitt

1965-01-01

224

Studies of earth stress and rock properties and the hydraulic-fracturing process  

NASA Astrophysics Data System (ADS)

The mechanics of hydraulic fracturing for enlarged gas recovery and the use of a minifrac technique for stress measurements at coal mines in the Appalachian and Rocky Mountain regions are discussed. These will be used to help design fracturing techniques to recover gas from gassy coal beds. Research to date indicates that fracture propagation is strongly influenced by existing stresses and that the stress gradient in a non-uniform stress field may stop or turn the fracture. Field evidence and analyses show that anisotropic rock properties due to rock fabric are a major factor in fracture geometry and calculated stress values.

Hanson, M.; Towse, D.

1982-04-01

225

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

226

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

227

Fully Coupled Geomechanics and Discrete Flow Network Modeling of Hydraulic Fracturing for Geothermal Applications  

SciTech Connect

The primary objective of our current research is to develop a computational test bed for evaluating borehole techniques to enhance fluid flow and heat transfer in enhanced geothermal systems (EGS). Simulating processes resulting in hydraulic fracturing and/or the remobilization of existing fractures, especially the interaction between propagating fractures and existing fractures, represents a critical goal of our project. To this end, we are continuing to develop a hydraulic fracturing simulation capability within the Livermore Distinct Element Code (LDEC), a combined FEM/DEM analysis code with explicit solid-fluid mechanics coupling. LDEC simulations start from an initial fracture distribution which can be stochastically generated or upscaled from the statistics of an actual fracture distribution. During the hydraulic stimulation process, LDEC tracks the propagation of fractures and other modifications to the fracture system. The output is transferred to the Non-isothermal Unsaturated Flow and Transport (NUFT) code to capture heat transfer and flow at the reservoir scale. This approach is intended to offer flexibility in the types of analyses we can perform, including evaluating the effects of different system heterogeneities on the heat extraction rate as well as seismicity associated with geothermal operations. This paper details the basic methodology of our approach. Two numerical examples showing the capability and effectiveness of our simulator are also presented.

Fu, P; Johnson, S M; Hao, Y; Carrigan, C R

2011-01-18

228

A model for turbulent hydraulic fracture and application to crack propagation at glacier beds  

NASA Astrophysics Data System (ADS)

Glaciological observations of under-flooding suggest that fluid-induced hydraulic fracture of an ice sheet from its bed sometimes occurs quickly, possibly driven by turbulently flowing water in a broad sheet flow. Taking the approximation of a fully turbulent flow into an elastic ice medium with small fracture toughness, we derive an approximate expression for the crack-tip speed, opening displacement and pressure profile. We accomplish this by first showing that a Manning-Strickler channel model for resistance to turbulent flow leads to a mathematical structure somewhat similar to that for resistance to laminar flow of a power law viscous fluid. We then adapt the plane-strain asymptotic crack solution of Desroches et al. (1994) and the power law self-similar solution of Adachi and Detournay (2002) for that case to calculate the desired quantities. The speed of crack growth is shown to scale as the overpressure (in excess of ice overburden) to the power 7/6, inversely as ice elastic modulus to the power 2/3, and as the ratio of crack length to wall roughness scale to the power 1/6. We tentatively apply our model by choosing parameter values thought appropriate for a basal crack driven by the rapid drainage of a surface meltwater lake near the margin of the Greenland Ice Sheet. Making various approximations perhaps relevant to this setting, we estimate fluid inflow rate to the basal fracture and vertical and horizontal surface displacements and find order-of-magnitude agreement with observations by Das et al. (2008) associated with lake drainage. Finally, we discuss how these preliminary estimates could be improved.

Tsai, Victor C.; Rice, James R.

2010-09-01

229

Prediction of hydraulic conductivity and conductive fracture frequency by multivariate analysis of data from the Klipperaas study site.  

National Technical Information Service (NTIS)

The present study is a pilot study on the possibility to predict the hydraulic conductivity and conductive fracture frequency in boreholes in crystalline rock using multivariate data analysis. The data set included data from core mapping, fracture filling...

J. E. Andersson L. Lindqvist

1989-01-01

230

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

2007-06-26

231

Hydraulic fracturing method using sintered bauxite propping agent  

Microsoft Academic Search

A method of fracturing a subterranean formation is described wherein particles composed of sintered bauxite are placed in the formation fracture to prop the fracture open. The sintered bauxite particles have a specific gravity greater than 3.4 and are prepared from bauxite material having a grain size of about 12 microns or less. The sintering process for producing the proppant

C. E. Jr. Cooke; W. A. Hedden; W. C. Chard

1978-01-01

232

Hydraulic fracturing method using sintered bauxite propping agent  

Microsoft Academic Search

An improved method of fracturing a subterranean formation is described wherein particles composed of sintered bauxite are placed in the formation fracture to maintain the walls of the fracture spaced apart. The sintered bauxite particles have a specific gravity greater than 3.4 and are prepared from bauxite material having a grain size of about 12 microns or less.

C. E. Jr. Cooke; W. A. Hedden; W. C. Chard

1978-01-01

233

Scattering by hydraulic fractures: Finite-difference modeling and laboratory data  

SciTech Connect

Reservoir production can be stimulated by creating hydraulic fractures that effectively facilitate the inflow of hydrocarbons into a well. Considering the effectiveness and safety of the operation, it is desirable to monitor the size and location of the fracture. In this paper, the authors investigate the possibilities of using seismic waves generated by active sources to characterize the fractures. First, the authors must understand the scattering of seismic waves by hydraulic fractures. For that purpose they use a finite-difference modeling scheme. They argue that a mechanically open hydraulic fracture can be represented by a thin, fluid-filled layer. The width or aperture of the fracture is often small compared to the seismic wavelength, which forces one to use a very find grid spacing to define the fracture. Based on equidistant grids, this results in a large number of grid points and hence computationally expensive problems. The authors show that this problem can be overcome by allowing for a variation in grid spacing in the finite-difference scheme to accommodate the large-scale variation in such a model. Second, they show ultrasonic data of small-scale hydraulic fracture experiments in the laboratory. At first sight it is difficult to unravel the interpretation of the various events measured. They use the results of the finite-difference modeling to postulate various possible events that might be present in the data. By comparing the calculated arrival times of these events with the laboratory and finite-difference data, they are able to propose a plausible explanation of the set of scattering events. Based on the laboratory data, they conclude that active seismic sources can potentially be used to determine fracture size and location in the field. The modeling example of fracture scattering illustrates the benefit of the finite-difference technique with a variation in grid spacing for comparing numerical and physical experiments.

Groenenboom, J.; Falk, J.

2000-04-01

234

Transient hydraulic tomography in a fractured dolostone: Laboratory rock block experiments  

NASA Astrophysics Data System (ADS)

The accurate characterization of fractured geologic medium, imaging of fracture patterns and their connectivity have been a challenge for decades. Recently, hydraulic tomography has been proposed as a new method for imaging the hydraulic conductivity (K) and specific storage (Ss) distributions of fractured geologic media. While encouraging results have been obtained in the field, the method has not been rigorously assessed in a controlled laboratory setting. In this study, we assess the performance of transient hydraulic tomography (THT) in a fractured dolomitic rock block. The block is characterized through flow-through tests and multiple pumping tests. The pumping test data were then analyzed with the THT code of Zhu and Yeh (2005) to image the fracture patterns and their connectivity through the delineation of K and Ss distributions (or tomograms). Results show that the THT analysis of pumping tests yields high-K and low-Ss zones that capture the fracture pattern and their connectivity quite well and those patterns become more vivid as additional pumping test data are added to the inverse model. The performance of the estimated K and Ss tomograms are then assessed by: (1) comparing the tomograms obtained from synthetic to real data; (2) comparing the tomograms from two different pumping configurations; (3) comparing the estimated geometric mean of the hydraulic conductivity (KG) from the K tomogram to the effective hydraulic conductivity (Keff) estimated from the flow-through tests; and (4) predicting five independent pumping tests not used in the construction of the K and Ss tomograms. The performance assessment of the K and Ss tomograms reveals that THT is able to image high-K and low-Ss zones that correspond to fracture locations in the fractured rock block and that the tomograms can be used to predict drawdowns from pumping tests not used in the construction of the tomograms with reasonable fidelity.

Sharmeen, Rubaiat; Illman, Walter A.; Berg, Steven J.; Yeh, Tian-Chyi J.; Park, Young-Jin; Sudicky, Edward A.; Ando, Ken

2012-10-01

235

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

236

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

237

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

2008-10-17

238

Mapping acoustic emissions from hydraulic fracture treatments using coherent array processing: Concept  

SciTech Connect

Hydraulic fracturing is a widely-used well completion technique for enhancing the recovery of gas and oil in low-permeability formations. Hydraulic fracturing consists of pumping fluids into a well under high pressure (1000--5000 psi) to wedge-open and extend a fracture into the producing formation. The fracture acts as a conduit for gas and oil to flow back to the well, significantly increasing communication with larger volumes of the producing formation. A considerable amount of research has been conducted on the use of acoustic (microseismic) emission to delineate fracture growth. The use of transient signals to map the location of discrete sites of emission along fractures has been the focus of most research on methods for delineating fractures. These methods depend upon timing the arrival of compressional (P) or shear (S) waves from discrete fracturing events at one or more clamped geophones in the treatment well or in adjacent monitoring wells. Using a propagation model, the arrival times are used to estimate the distance from each sensor to the fracturing event. Coherent processing methods appear to have sufficient resolution in the 75 to 200 Hz band to delineate the extent of fractures induced by hydraulic fracturing. The medium velocity structure must be known with a 10% accuracy or better and no major discontinuities should be undetected. For best results, the receiving array must be positioned directly opposite the perforations (same depths) at a horizontal range of 200 to 400 feet from the region to be imaged. Sources of acoustic emission may be detectable down to a single-sensor SNR of 0.25 or somewhat less. These conclusions are limited by the assumptions of this study: good coupling to the formation, acoustic propagation, and accurate knowledge of the velocity structure.

Harris, D.B.; Sherwood, R.J.; Jarpe, S.P.; Harben, P.E.

1991-09-01

239

Assessing and improving steam-assisted gravity drainage: Reservoir heterogeneities, hydraulic fractures, and mobility control foams  

NASA Astrophysics Data System (ADS)

Steam-assisted gravity drainage (SAGD) is a promising approach for recovering heavy and viscous oil resources. In SAGD, two closely-spaced horizontal wells, one above the other, form a steam-injector and producer pair. The reservoir oil is heated by the injected steam and drains to the producer under the effect of gravity. The success of steam-assisted gravity drainage has been demonstrated by both field and laboratory studies mostly based on homogeneous reservoirs and reservoir models. A comprehensive understanding of the effects of reservoir heterogeneities on SAGD performance, however, is required for wider and more successful implementation. This dissertation presents an investigation of the effects of reservoir heterogeneities on SAGD. In addition, two potential methods, hydraulic fracturing and mobility control using foamed steam, are proposed and reported here to enhance SAGD performance, especially for heterogeneous reservoirs. Reservoir simulations of SAGD are conducted with a number of realizations of Athabasca-type oilsand reservoirs that contain randomly-distributed shales geostatistically generated with a stochastic model. We interpret the complex effects of reservoir heterogeneities by identifying two flow regions, the near well region (NWR) and the above well region (AWR). Our simulations indicate that the drainage flow of hot fluids within the NWR, characterized by short flow length, is very sensitive to the presence of shale, whereas the expansion of the steam chamber in the AWR, characterized by long flow length, is affected adversely only when the AWR contains long, continuous shale or a high fraction of shale. Vertical hydraulic fractures are found to improve steam chamber development considerably for reservoirs with poor vertical communication. For the synthetic reservoir under study, an increase in the oil production rate by a factor of two and considerable improvement of energy efficiency with the cumulative oil-steam ratio lifted from 0.2 to 0.3 bbl oil/bbl CWE steam are achieved by adding a vertical fracture. The new concept of foam-assisted SAGD (FA-SAGD) is evaluated numerically with a foam simulator that incorporates the physical mechanisms of foam generation, destruction, and transport. To reduce computational costs, we develop a simplified foam model based on the assumption of local equilibrium of foam generation and coalescence at field scale. Foam displacements in a linear sandstone core are measured using pressure transducers, X-ray Computed Tomography (CT), and a visualization cell to quantify foam bubble texture. The local equilibrium approximation is validated, and good agreement between the experimental results and the predictions of the simplified model is found, with a minor mismatch in the entrance region. For the scenario under study, numerical simulation of the FA-SAGD process shows considerable improvement in the process efficiency over the conventional SAGD process. Live steam production is reduced by a factor of 5 for FA-SAGD compared to conventional SAGD. Consequently, cumulative oil production is increased by about 30% when production versus the volume of steam injected is compared for cases with and without foam.

Chen, Qing

240

The importance of in-situ-stress profiles in hydraulic-fracturing applications  

SciTech Connect

In-situ stresses define the local forces acting on lithologic layers in the subsurface. Knowledge of these stresses is important in drilling, wellbore-stability, and, especially, hydraulic-fracturing applications. The measurement of in-situ stress is not straightforward and, therefore, often goes unmeasured. As such, one often assumes values of in-situ stress or estimate in-situ stresses from logging parameters. This article illustrates the importance of in-situ-stress estimates as they relate to hydraulic fracturing and outlines several techniques for estimating in-situ-stress magnitudes.

Hopkins, C.W. [S.A. Holditch and Associates, Inc., Houston, TX (United States). Houston Div.

1997-09-01

241

Hydraulic Transport of Sand and Lime Slurries in a Vertical Pipeline  

Microsoft Academic Search

This thesis is primarily concerned with the energy required to hydraulically transport sand and lime slurries in a 5.1 cm.-diameter vertical pipeline for both steady and pulsating flows.\\u000aIn the steady flow experiments, three different grades of sand of average weighted diameter d = 0.66, 1.20 and 1.84 mm. were investigated. The lime flurry used had an average particle diameter

Brian L. Joel

1980-01-01

242

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.

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

2012-01-01

243

Hydraulic fracturing stimulation techniques and formation damage mechanisms—Implications from laboratory testing of tight sandstone–proppant systems  

Microsoft Academic Search

Reservoir formation damage may seriously affect the productivity of a reservoir during various phases of fluid recovery from the subsurface. Hydraulic fracturing technology is one tool to overcome inflow impairments due to formation damage and to increase the productivity of reservoirs. However, the increase in productivity by hydraulic fracturing operations can be limited by permeability alterations adjacent to the newly

Andreas Reinicke; Erik Rybacki; Sergei Stanchits; Ernst Huenges; Georg Dresen

2010-01-01

244

HYDRAULIC CHARACTERIZATION FOR STEAM ENHANCED REMEDIATION CONDUCTED IN FRACTURED ROCK  

EPA Science Inventory

Remediation of fractured rock sites contaminated by non-aqueous phase liquids has long been recognized as the most difficult undertaking of any site clean-up. This is primarily the result of the complexity of the fracture framework, which governs the groundwater flow pathways and...

245

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

246

Hydraulic-fracture growth in dipping anisotropic strata as viewed through the surface deformation field  

SciTech Connect

In 1983 and 1984 Oak Rdige National Laboratory conducted a series of precision ground deformation measurements before, during, and after the generation of several large hydraulic fractures in a dipping member of the Cambrian Conasauga Shale. Each fracture was produced by the injection of approximately 500,000 L of slurry on a single day. Injection depth was 300 m. Leveling surveys were run several days before and several days after the injections. An array of eight high-precision borehole tiltmeters monitored ground deformations continuously for a period of several weeks. Analysis of the leveling and the tilt measurements revealed surface uplifts as great as 25 mm and tilts of tens of microradians during each injection. Furthermore, partial recovery (subsidence) of the ground took place during the days following an injection, accompanied by shifts in the position of maximum resultant uplift. Interpretation of the tilt measurements is consistent with stable widening and extension of hydraulic fractures with subhorizontal orientations. Comparison of the measured tilt patterns with fracture orientations established from logging of observation wells suggests that shearing parallel to the fracture planes accompanied fracture dilation. This interpretation is supported by measured tilts and ground uplifts that were as much as 100 percent greater than those expected from fracture dilation alone. Models of elastically anisotropic overburden rock do not explain the measured tilt patterns in the absence of shear stresses in the fracture planes. This work represents the first large-scale hydraulic-fracturing experiment in which the possible effects of material anisotropy and fracture-parallel shears have been measured and interpreted.

Holzhausen, G.R.; Haase, C.S.; Stow, S.H.; Gazonas, G.

1985-01-01

247

Microseismic Mapping of Hydraulic Fractures Using MultiLevel Wireline Receivers  

Microsoft Academic Search

Hydraulic fracture diagnostic experiments are being conducted at the GRI\\/DOE Multi-Site (M-Site) located in the Piceance basin of Colorado. Tests described in this paper use a multi-level advanced-receiver system to build on previous work that showed the advantages of using a single advanced receiver to monitor microseisms. The current test has a four-level receiver system monitoring four separate fracture experiments

N. R. Warpinski; B. P. Engler; C. J. Young; R. Peterson; P. T. Branagan; J. E. Fix

1995-01-01

248

Preliminary assessment of a geothermal energy reservoir formed by hydraulic fracturing  

Microsoft Academic Search

Two, 3-km-deep boreholes have been drilled into hot (approximately 200 C) graphite in northern New Mexico in order to extract geothermal energy from hot dry rock. Both boreholes were hydraulically fractured to establish a flow connection. Presently this connection has a large flow impedance which may be improved with further stimulation. Fracture-to-borehole intersection locations and in situ thermal conductivity were

H. D. Murphy; R. G. Lawton; J. W. Tester; R. M. Potter; D. W. Brown; R. L. Aamodt

1976-01-01

249

Hydraulic fracture stimulation treatment of Well Baca 23. Geothermal Reservoir Well-Stimulation Program  

SciTech Connect

Well Stimulation Experiment No. 5 of the Geothermal Reservoir Well Stimulation Program (GRWSP) was performed on March 22, 1981 in Baca 23, located in Union's Redondo Creek Project Area in Sandoval County, New Mexico. The treatment selected was a large hydraulic fracture job designed specifically for, and utilizing frac materials chosen for, the high temperature geothermal environment. The well selection, fracture treatment, experiment evaluation, and summary of the job costs are presented herein.

Not Available

1981-06-01

250

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

251

Effect of rock rheology on fluid leak- off during hydraulic fracturing  

NASA Astrophysics Data System (ADS)

In this communication, we evaluate the effect of rock rheology on fluid leak­off during hydraulic fracturing of reservoirs. Fluid leak-off in hydraulic fracturing is often nonlinear. The simple linear model developed by Carter (1957) for flow of fracturing fluid into a reservoir has three different regions in the fractured zone: a filter cake on the fracture face, formed by solid additives from the fracturing fluid; a filtrate zone affected by invasion of the fracturing fluid; and a reservoir zone with the original formation fluid. The width of each zone, as well as its permeability and pressure drop, is assumed to remain constant. Physical intuition suggests some straightforward corrections to this classical theory to take into account the pressure dependence of permeability, the compressibility or non-Newtonian rheology of fracturing fluid, and the radial (versus linear) geometry of fluid leak­off from the borehole. All of these refinements, however, still assume that the reservoir rock adjacent to the fracture face is non­deformable. Although the effect of poroelastic stress changes on leak-off is usually thought to be negligible, at the very high fluid pressures used in hydraulic fracturing, where the stresses exceed the rock strength, elastic rheology may not be the best choice. For example, calculations show that perfectly elastic rock formations do not undergo the degree of compaction typically seen in sedimentary basins. Therefore, pseudo-elastic or elastoplastic models are used to fit observed porosity profiles with depth. Starting from balance equations for mass and momentum for fluid and rock, we derive a hydraulic flow equation coupled with a porosity equation describing rock compaction. The result resembles a pressure diffusion equation with the total compressibility being a sum of fluid, rock and pore-space compressibilities. With linear elastic rheology, the bulk formation compressibility is dominated by fluid compressibility. But the possibility of permanent, time-independent (plastic) rock deformation significantly increases the pore space compressibility (compaction), which becomes a leading term in the total compressibility. Inclusion of rock and fluid compressibilities in the model can explain both linear and nonlinear leak­off. In particular, inclusion of rock compaction and decompaction may be important for description of naturally fractured and tight gas reservoirs for which very strong dependence of permeability on porosity has been reported. Carter R.D. Derivation of the general equation for estimating the extent of the fractured area. Appendix I of "Optimum fluid characteristics for fracture extension", Drilling and Production Practice, G.C. Howard and C.R.Fast, New York, New York, USA, American Petroleum Institute (1957), 261-269.

Yarushina, V. M.; Bercovici, D.; Oristaglio, M. L.

2012-04-01

252

Geometry of hydraulic fractures induced from horizontal wellbores  

SciTech Connect

In the Dan field, very high breakdown pressures were observed for wellbores drilled with a high azimuth with respect to the preferred fracture plane. The increased breakdown pressure was caused by significant near-wellbore friction. In scaled laboratory tests, variation in breakdown pressure was accompanies by a change in fracture geometry. Therefore, the variation in breakdown pressure in the field treatments could not be related simply to in-situ stresses.

Weijers, L.; De Pater, C.J. (Delft Univ. of Technology (Netherlands)); Owens, K.A.; Kogsboell, H.H. (Maersk Oil and Gas A/S, Copenhagen (Denmark))

1994-05-01

253

Optimizing Well Spacing and Hydraulic-Fracture Design for Economic Recovery of Coalbed Methane  

Microsoft Academic Search

Conventionally, proper well spacing and stimulation govern the economic attractiveness of producing natural gas from coalbeds. To provide an analytical foundation for this empirical evidence, reservoir simulation and economic analyses were conducted to gain insights into the optimum well spacing and hydraulic-fracturing treatments in typical good and poor geologic settings of the Oak Grove field in Alabama. The authors report

Michael Zuber; Vello Kuuskraa; W. K. Sawyer

1990-01-01

254

Hydraulic fracturing to improve nutrient and oxygen delivery for in-situ bioreclamation  

Microsoft Academic Search

A serious problem in the implementation of in situ bioreclamation is the delivery of nutrients and oxygen to soil of low permeability. The problem commonly requires contaminated soil to be excavated for bioreclamation, resulting in increased exposure to toxic materials, liability and cost. The authors demonstrated that is feasible to create hydraulic fractures at shallow depths (several m) in silty

S. J. Versper; W. J. Davis-Hoover; L. C. Murdoch; H. R. Pahren; O. L. Sprockel

1991-01-01

255

Massive Hydraulic Fracture Mapping and Characterization Program. Surface Potential Data for Wattenberg 1975--1976 Experiments.  

National Technical Information Service (NTIS)

Three massive hydraulic fracture experiments for natural gas stimulation were conducted by Halliburton for AMOCO in the Wattenberg field northeast of Denver, Colorado. The experiments were conducted on three wells--Martin Hart ''E'' No. 1, Salazar G.U. No...

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

1977-01-01

256

Environmental Justice and Hydraulic Fracturing: The Ascendancy of Grassroots Populism in Policy Determination  

Microsoft Academic Search

Exploration and development of natural gas resources includes the use of hydraulic fracturing, a process that can potentially contaminate domestic water sources. While industry seeks access to BLM leases for new wells, their proximity to communities can have serious negative consequences on their health and life style, raising questions of how sites are selected and concerns about environmental justice. This

Nancy C Carre

2012-01-01

257

In-situ heat transfer in man-made hydraulically fractured geothermal energy reservoirs  

Microsoft Academic Search

Heat extraction results and reservoir assessments are discussed for 2 geothermal reservoirs created by hydraulic fracturing of hot granitic formations on the west flank of the Valles Caldera, a dormant volcano, in the Jemez Mt. of New Mexico. The second reservoir was created in a deeper rock formation using the same pair of operation wells, and appears to be approximately

H. D. Murphy; J. W. Tester; C. Grigsby; R. M. Potter

1980-01-01

258

A study of stress determination in rock salt by the method of hydraulic fracturing  

Microsoft Academic Search

In salt, creep and plastic mechanisms are postulated to create stress-relaxed zones around a borehole. To help determine the effectiveness of the stress measurement technique of hydraulic fracturing in salt, this dissertation describes the problem of stress distribution around the borehole and the extensive laboratory program conducted to determine the effects of time, pressure, flow rate, borehole size, packer configurations,

Boyce

1988-01-01

259

An Asymptotic Framework for Finite Hydraulic Fractures Including Leak-Off  

Microsoft Academic Search

The dynamics of hydraulic fracture, described by a system of nonlinear integro- differential equations, is studied through the development and application of a multiparameter sin- gular perturbation analysis. We present a new single expansion framework which describes the interaction between several physical processes, namely viscosity, toughness, and leak-off. The prob- lem has nonlocal and nonlinear effects which give a complex

S. L. Mitchell; R. Kuske; A. P. Peirce

2007-01-01

260

A data processing software package for passive seismic monitoring of hydraulic fracturing  

Microsoft Academic Search

A data processing software package is developed for passive seismic monitoring of hydraulic fracturing. The original seismic data is acquired by a surface array which has many stations work independently. The package converts original data files into SEG-Y format files, and files of all stations are synchronized and combined according to GPS time. Many methods are utilized to perform signal

Weibo Wang; Yu Sang; Jie Kong; Yaoqi Zhou

2011-01-01

261

Evaluation of Massive Hydraulic Fracturing Experiments in the Devonian Shale in Lincoln County, West Virginia.  

National Technical Information Service (NTIS)

The report summarizes the final results, conclusions, and recommendations from a review of the Columbia/DOE Massive Hydraulic Fracturing (MHF) Project. The major objective of the study was to apply GRI-developed technology and other modern technology to t...

J. Gatens K. E. Holgate W. J. Lee

1987-01-01

262

Environmental Impact Assessment: Enhanced Gas Recovery by Massive Hydraulic Fracturing in Lincoln County, West Virginia.  

National Technical Information Service (NTIS)

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...

J. K. Schnorr

1978-01-01

263

USE OF HIGH-STRENGTH CERAMIC BEADS FOR PROPPING DEEP HYDRAULIC FRACTURES  

Microsoft Academic Search

Ceramic beads have been tested to be used as propping agents in a hydraulic fracturing process. This material is zirconium oxide based. Its main properties are described. Laboratory tests on various beads concentrations show a good conductivity of the proppant under compressive stresses of at least 15,000 psi. Good results also have been obtained in permeability tests at high temperature

Jean Sarda

1978-01-01

264

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

265

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

266

Active and Passive Seismic Imaging of a Hydraulic Fracture in Diatomite  

Microsoft Academic Search

This paper reports on a comprehensive set of experiments including remote- and treatment-well microseismic monitoring, interwell shear-wave shadowing, and surface tiltmeter arrays, that was used to monitor the growth of a hydraulic fracture in the Belridge diatomite. To obtain accurate measurements, and extensive subsurface network of geophones was cemented spanning the diatomite formation in three closely spaced observation wells around

H. J. Vinegar; P. B. Wills; D. C. DeMartini; J. Shlyapobersky; W. F. J. Deeg; R. G. Adair; J. C. Woerpel; J. E. Fix; G. G. Sorrells

1992-01-01

267

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

268

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

269

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

270

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

271

Use of well logs to provide formation design values for hydraulic fracture treatments  

SciTech Connect

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 is shown how the formation design parameter values provided by well logging can be used for computer-based numerical simulations aimed at analyzing fracture treatment and post-fracture performance of oil wells. Refs.

Ameri, S.; Rieke, H.H. III

1981-01-01

272

Microseismic mapping of hydraulic fractures using multi-level wireline receivers  

SciTech Connect

Hydraulic fracture diagnostic experiments are being conducted at the GRI/DOE Multi-Site (M-Site) located in the Piceance basin of Colorado. Tests described in this paper use a multi-level advanced-receiver system to build on previous work that showed the advantages of using a single advanced receiver to monitor microseisms. The current test has a four-level receiver system monitoring four separate fracture experiments conducted over a one week period, and includes a velocity tomographic survey and detailed orientation survey. Hydraulic fractures were monitored from an offset well 210 ft away from the treatment well. The results of these monitoring tests show a fracture developing asymmetrically with time, yielding a fracture-wing asymmetry of 2:1. The fracture initially grows within the pay zone to essentially its total length, and then begins to grow upward, and later in time grow downward. Comparison with fracture models gives only a partial agreement in the final size.

Warpinski, N.R.; Engler, B.P.; Young, C.J. [Sandia National Labs., Albuquerque, NM (United States); Peterson, R.; Branagan, P.T.; Fix, J.E.

1995-07-01

273

Correlating laboratory observations of fracture mechanical properties to hydraulically-induced microseismicity in geothermal reservoirs.  

SciTech Connect

To date, microseismicity has provided an invaluable tool for delineating the fracture network produced by hydraulic stimulation of geothermal reservoirs. While the locations of microseismic events are of fundamental importance, there is a wealth of information that can be gleaned from the induced seismicity (e.g. fault plane solutions, seismic moment tensors, source characteristics). Closer scrutiny of the spatial and temporal evolution of seismic moment tensors can shed light on systematic characteristics of fractures in the geothermal reservoir. When related to observations from laboratory experiments, these systematic trends can be interpreted in terms of mechanical processes that most likely operate in the fracture network. This paper reports on mechanical properties that can be inferred from observations of microseismicity in geothermal systems. These properties lead to interpretations about fracture initiation, seismicity induced after hydraulic shut-in, spatial evolution of linked fractures, and temporal evolution of fracture strength. The correlations highlight the fact that a combination of temperature, stressing rate, time, and fluid-rock interactions can alter the mechanical and fluid transport properties of fractures in geothermal systems.

Stephen L. Karner, Ph.D

2006-02-01

274

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

275

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

276

Effect of boundary conditions, impact loading and hydraulic stiffening on femoral fracture strength.  

PubMed

Patient specific quantitative CT (QCT) imaging data together with the finite element (FE) method may provide an accurate prediction of a patient's femoral strength and fracture risk. Although numerous FE models investigating femoral fracture strength have been published, there is little consent on the effect of boundary conditions, dynamic loading and hydraulic strengthening due to intra-medullary pressure on the predicted fracture strength. We developed a QCT-derived FE model of a proximal femur that included node-specific modulus assigned based on the local bone density. The effect of three commonly used boundary conditions published in literature were investigated by comparing the resulting strain field due to an applied fracture load. The models were also augmented with viscoelastic material properties and subject to a realistic impact load profile to determine the effect of dynamic loads on the strain field. Finally, the effect of hydraulic strengthening was investigated by including node specific permeability and performing a coupled pore diffusion and stress analysis of the FE model. Results showed that all boundary conditions yield the same strain field patterns, but peak strains were 22% lower and fracture load was 18% higher when loaded at the greater trochanter than when loaded at the femoral head. Comparison of the dynamic models showed that material viscoelasticity was important, but inertial effects (vibration and shock) were not. Finally, pore pressure changes did not cause significant hydraulic strengthening of bone under fall impact loading. PMID:23906770

Haider, Ifaz T; Speirs, Andrew D; Frei, Hanspeter

2013-07-30

277

Scale Dependence of Hydraulic and Structural Parameters In Fractured Rock From Borehole Data (ktb and Hsdp)  

NASA Astrophysics Data System (ADS)

Fundamental understanding of the origin, geometry, extension and scale dependence of fluid pathways in fractured rock is still incomplete. We analysed fracture networks on different scales based on data from fluorescent thinsections and BHTV images from the same depth range to obtain geometrical network parameters and to estimate frac- ture permeability in the vicinity of a mantle plume (Hawaii Scientific Drilling Project, HSDP). A first modelling of a microscopic network from the fluorescent thinsection of a highly olivine phyric basalt gives a clear indication, that the preferential hydraulic pathways on the microscopic scale are in this particular case the micro fractures in the olivine crystal. This is the only plausible explanation of high porosity (16.6 %) due to the observed vesicles and a corresponding low permeability of 10 µD measured on core samples. Modelling hydraulic flow and calculation of permeability leads to simi- lar values of permeability of 12.3 µD assuming a mean fracture aperture of 1 µm and an exponential distribution function of the fractures. Detected structures from BHTV measurements were used to construct a macroscopic stochastic network to simulate the hydraulic flow on a macroscopic scale. We found 337 fractures in the depth section from 783.5 m to 1147.5 m, which result in a linear frequency of 0.927 1/m. Assum- ing horizontal layers and constant fracture apertures of 100 µm for all structures lead to a first estimate of permeability of 77 mD in this depth section. In a recent work, we showed for data from the Continental Deep Drilling Project (KTB) that the frac- ture density versus fracture length follows a power law. The results from the Hawaiian data suggest a similar relationship, despite all differences in the lithological conditions between both sites.

Zimmermann, G.; Burkhardt, H.; Engelhard, L.

278

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

SciTech Connect

This report describes the work performed during the second 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 less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on investigating the effect of CO{sub 2} injection rates in homogeneous and fractured cores on oil recovery and a strategy to mitigate CO{sub 2} bypassing in a fractured core.

David S. Schechter

2004-04-26

279

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

SciTech Connect

This report describes the work performed during the second 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 less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.

David S. Schechter

2003-10-01

280

Hydraulic-fracture stimulation treatments at East Mesa, Well 58-30. Geothermal-reservoir well-stimulation program  

SciTech Connect

East Mesa Well 58-30 was selected for two stimulation treatments: a conventional hydraulic fracture in a deep, low permeability interval, and a dendritic fracture in a shallow, high permeability interval of completion. The well selection, pre-stimulation evaluation, fracture treatment design, and post-stimulation evaluation are presented.

Not Available

1981-02-01

281

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

282

The Effect of Mineral Deposition on the Hydraulic and Seismic Properties of Fractures  

NASA Astrophysics Data System (ADS)

Fractures and other subsurface discontinuities can be altered over time from geochemical interaction with the pore fluids. Alteration of the pore space in a fracture will affect the seismic and hydraulic properties of a fracture. Mineral deposition can alter the fracture specific stiffness by changing the size and strength of the contact area and/or filling-in the void space which will reduce the flow rate. We performed acoustic imaging experiments on single fractures in granite to determine the effect of mineral deposition on the seismic and hydraulic properties of single fractures. Prior to and after mineral precipitation (CaCO3), the samples (110 mm x 104 mm x 70 mm) were imaged over a 64 mm by 64 mm region using transmitted compressional waves (~1 Mhz). Eight ports were distributed around the perimeter of the fracture to measure the variation in flow as a function of position, as well as prior to and after chemical invasion. After mineral precipitation, the flow rate decreased by approximately 90%. The decrease in flow rate can be attributed to reduction of the fracture aperture and blocking of flow paths by mineralization. We observed that the initial void geometry controlled the amount and spatial distribution of mineral deposition within the fracture. The most reliable seismic indicator that the fracture had been altered was a reduction in the variance of the frequency distribution of the received signal. The reduced variance indicates that the fracture is homogenized by mineral deposition in the fracture voids (i.e. tending toward a move uniform fracture stiffness). Homogenization occurs because the mixing predominantly takes place in the dominant flow paths within the fracture, which tend to have lower fracture stiffness. The results indicate that acoustic imaging techniques are required in this characterization because they provide statistical indicators that help monitor changes in fracture geometry caused by mineral deposition. Acknowledgments: Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy. LJPN wishes to acknowledge University Faculty Scholar program at Purdue University

Gilbert, Z. A.; Acosta-Colon, A. A.; Pyrak-Nolte, L. J.

2004-12-01

283

Research on the hydraulic turbine vertical vibration power flow in the head cover system  

NASA Astrophysics Data System (ADS)

On the basis of the prior models about the vertical vibration of the hydraulic vibration source, this research introduced a sub-system—head cover. Head cover is one of the main paths when vibration is transferred from the water vibration source to the stable structure. This essay aims to analyze the hydraulic turbine vertical vibration power flow in the head cover system. The research is based on the power flow theory and the probability perturbation method; meanwhile, it considered on the reciprocal coupling effect of the water machine parts and power house structure, etc. Therefore, the results of can clearly provide the random power flow of the vibration transfer path system, which including the head cover system, in frequency domain by given of some uncertain factors in one project. In conclusions, the research provide an overall analysis on the hydropower station vertical vibration transfer path; and it suggest some simplified and efficient solutions in the analysis on the vibration path with some random parameters.

Zhi, B. P.; Ma, Z. Y.

2012-11-01

284

Permeability Distribution In A Confined Fracture Flow Aquifer Using Hydraulic Testing and Borehole Geophysics  

NASA Astrophysics Data System (ADS)

Groundwater is one of the main drinking water resources in the United Kingdom and the Chalk aquifer contributes over 50 % of the abstracted amount. The Chalk consists of a highly porous matrix which is intersected by hydraulically conductive fractures representing the main flow pathways. Hydraulic testing and borehole geophysics were carried out at a test site in East Yorkshire (Northern England), in order to characterise the permeability distribution at the site prior to conducting tracer tests. The Chalk at the fieldsite is confined by about 11m glacial and postglacial lacustrine deposits, and the upper 12m of Chalk has been affected by periglacial weathering. Five boreholes were drilled to 70 to 80m depth; one of these was cored. The intact Chalk contains stylolites (pressure dissolution surfaces), marl bands up to 1.5cm thick, faults, and several sets of inclined joints. The core and acoustic televiewer images from all five boreholes show a high fracture density in the depth interval from 25 to 32m, and discrete fractured zones below this depth. Packer tests on the cored borehole yielded hydraulic conductivities of 6.6OE10-5 to 3.7OE10-6m/s, which agree with the average hydraulic conductivity obtained from the pumping test. Fluid temperature and con- ductivity logging combined with static and pumped borehole flow logging showed that minor inflows and outflows were present throughout, but that several horizons of higher inflow/outflow were detected, which corresponded to highly fractured zones seen in acoustic televiewer images. Both packer tests and borehole geophysical log- ging indicate that most of the permeability of the aquifer is in the upper, highly frac- tured zone, but that discrete zones of high permeability are also present at depth. The acoustic televiewer was able to detect steep fractures that were not recognisable in the core, because the core was broken and fragmented during drilling due to the presence of these fractures.

Hartmann, S.; Odling, N. E.; West, L. J.

285

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

286

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...

287

Numerical evaluation of effective unsaturated hydraulic properties for fractured rocks  

SciTech Connect

To represent a heterogeneous unsaturated fractured rock by its homogeneous equivalent, Monte Carlo simulations are used to obtain upscaled (effective) flow properties. In this study, we present a numerical procedure for upscaling the van Genuchten parameters of unsaturated fractured rocks by conducting Monte Carlo simulations of the unsaturated flow in a domain under gravity-dominated regime. The simulation domain can be chosen as the scale of block size in the field-scale modeling. The effective conductivity is computed from the steady-state flux at the lower boundary and plotted as a function of the averaging pressure head or saturation over the domain. The scatter plot is then fitted using van Genuchten model and three parameters, i.e., the saturated conductivity K{sub s}, the air-entry parameter {alpha}, the pore-size distribution parameter n, corresponding to this model are considered as the effective K{sub s}, effective {alpha}, and effective n, respectively.

Lu, Zhiming [Los Alamos National Laboratory; Kwicklis, Edward M [Los Alamos National Laboratory

2009-01-01

288

Normal-stress dependence of fracture hydraulic properties including two-phase flow properties  

NASA Astrophysics Data System (ADS)

A systematic approach has been developed for determining relationships between normal stress and fracture hydraulic properties, including two-phase flow properties. The development of a relationship between stress and fracture permeability (or fracture aperture and fracture closure) is based on a two-part Hooke's model (TPHM) that captures heterogeneous elastic-deformation processes at a macroscopic scale by conceptualizing the rock mass (or a fracture) into two parts with different mechanical properties. The developed relationship was verified using a number of datasets in the literature for fracture closure versus stress, and satisfactory agreements were obtained. TPHM was previously shown to be able to accurately represent testing data for porous media as well. Based on the consideration that fracture-aperture distributions under different normal stresses can be represented by truncated-Gaussian distributions, closed-form constitutive relationships were developed between capillary pressure, relative permeability and saturation, for deformable horizontal fractures. The usefulness of these relationships was demonstrated by their consistency with a laboratory dataset.

Liu, Hui-Hai; Wei, Ming-Yao; Rutqvist, Jonny

2013-03-01

289

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

290

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

291

Vertical series hydraulic conductance classes to characterize the unsaturated zone in North Carolina  

USGS Publications Warehouse

This web site contains the Federal Geographic Data Committee-compliant metadata (documentation) for digital data produced for the North Carolina, Department of Environment and Natural Resources, Public Water Supply Section, Source Water Assessment Program. The metadata are for 11 individual Geographic Information System data sets. An overlay and indexing method was used with the data to derive a rating for unsaturated zone and watershed characteristics for use by the State of North Carolina in assessing more than 11,000 public water-supply wells and approximately 245 public surface-water intakes for susceptibility to contamination. For ground-water supplies, the digital data sets used in the assessment included unsaturated zone rating, vertical series hydraulic conductance, land-surface slope, and land cover. For assessment of public surface-water intakes, the data sets included watershed characteristics rating, average annual precipitation, land-surface slope, land cover, and ground-water contribution. Documentation for the land-use data set applies to both the unsaturated zone and watershed characteristics ratings. Documentation for the estimated depth-to-water map used in the calculation of the vertical series hydraulic conductance also is included.

Eimers, Jo Leslie; Terziotti, Silvia; Ferrell, Gloria M.

2001-01-01

292

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

293

Fractional flow dimensions and hydraulic properties of a fracture-zone aquifer, Leppävirta, Finland  

Microsoft Academic Search

In order to characterize the hydraulic properties of an aquifer in Finland comprising two subvertical fracture zones, observation-well\\u000a responses were matched with generalized radial flow (GRF) type curves. The responses in six wells out of seven are consistent\\u000a with the GRF model. The fractional flow dimensions (1–1.2 and 1.5) were determined by regression analysis of straight-line\\u000a slopes and type-curve matching.

J. Leveinen; E. Rönkä; J. Tikkanen; E. Karro

1998-01-01

294

Proppant Backproduction During Hydraulic Fracturing-A New Failure Mechanism for Resin-Coated Proppants  

Microsoft Academic Search

Backproduction of proppant from hydraulically fractured wells, particularly those completed in the northern European Rotliegend formation, is a major operational problem, necessitating costly and manpower-intensive surface-handling procedures. Further, the development of unmanned platform operations offshore, required in today's economic climate, is impossible as long as this problem remains unsolved. The most cost-effective potential solution to this problem is provided by

R. J. Vreeburg; L. P. Roodhart; D. R. Davies; G. S. Penny

1994-01-01

295

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

296

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

297

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.

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

2012-01-01

298

Initiation and propagation of a PKN hydraulic fracture in permeable rock: Toughness dominated regime  

NASA Astrophysics Data System (ADS)

The present work investigates the injection of a low-viscosity fluid into a pre-existing fracture with constrained height (PKN), as in waterflooding or supercritical CO2 injection. Contrary to conventional hydraulic fracturing, where 'cake build up' limits diffusion to a small zone, the low viscosity fluid allows for diffusion over a wider range of scales. Over large injection times the pattern becomes 2 or 3-D, necessitating a full-space diffusion modeling. In addition, the dissipation of energy associated with fracturing of rock dominates the energy needed for the low-viscosity fluid flow into the propagating crack. As a result, the fracture toughness is important in evaluating both the initiation and the ensuing propagation of these fractures. Classical PKN hydraulic fracturing model, amended to account for full-space leak-off and the toughness [Garagash, unpublished 2009], is used to evaluate the pressure history and fluid leak-off volume during the injection of low viscosity fluid into a pre-existing and initially stationary. In order to find the pressure history, the stationary crack is first subject to a step pressure increase. The response of the porous medium to the step pressure increase in terms of fluid leak-off volume provides the fundamental solution, which then can be used to find the transient pressurization using Duhamel theorem [Detournay & Cheng, IJSS 1991]. For the step pressure increase an integral equation technique is used to find the leak-off rate history. For small time the solution must converge to short time asymptote, which corresponds to 1-D diffusion pattern. However, as the diffusion length in the zone around the fracture increases the assumption of a 1-D pattern is no longer valid and the diffusion follows a 2-D pattern. The solution to the corresponding integral equation gives the leak-off rate history, which is used to find the cumulative leak-off volume. The transient pressurization solution is obtained using global conservation of fluid injected into the fracture. With increasing pressure in the fracture due to the fluid injection, the energy release rate eventually becomes equal to the toughness and fracture propagates. The evolution of the fracture length is established using the method similar to the one employed for the stationary crack.

Sarvaramini, E.; Garagash, D.

2011-12-01

299

Asymptotic analysis of cross-hole hydraulic tests in fractured granite.  

PubMed

Illman and Tartakovsky (2005a, 2005b) developed a new approach for the interpretation of three-dimensional pneumatic well tests conducted in porous or fractured geologic media, which is based on a straight-line analysis of late-time data. We modify this approach to interpret three-dimensional well tests in the saturated zone and use it to analyze the cross-hole hydraulic test data collected in the Full-Scale Engineered Barrier Experiment gallery at the Grimsel Test Site in Switzerland. The equivalent hydraulic conductivity and specific storage obtained from our analysis increase with the radial distance between the centroids of the pumping and monitoring intervals. Since this scale effect is observed from a single test type (cross-hole tests), it is less ambiguous than scale effects typically inferred from laboratory and multiple types of hydraulic tests (e.g., slug, single- and cross-hole tests). The statistical analysis of the estimated hydraulic parameters shows a strong correlation between equivalent hydraulic conductivity and specific storage. PMID:16857033

Illman, Walter A; Tartakovsky, Daniel M

300

Stress trajectory and advanced hydraulic-fracture simulations for the Eastern Gas Shales Project. Final report, April 30, 1981-July 30, 1983  

SciTech Connect

A summary review of hydraulic fracture modeling is given. Advanced hydraulic fracture model formulations and simulation, using the finite element method, are presented. The numerical examples include the determination of fracture width, height, length, and stress intensity factors with the effects of frac fluid properties, layered strata, in situ stresses, and joints. Future model extensions are also recommended. 66 references, 23 figures.

Advani, S.H.; Lee, J.K.

1983-01-01

301

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…

Engelbrecht, Nancy; And Others

302

Laboratory data in support of hydraulically fracturing EGSP OH Well No. 3. Final report  

SciTech Connect

Geologic and geophysical interpretations of data from the EGSP OH Well No. 3 show that an organically lean shale has a gradual transition with depth to an organically rich shale and that two layers (bound each shale formation. The laboratory test program was designed to understand the containment and productivity of a hydraulic fracture induced in this well to enhance gas production from the shale. The porosity in the formations of interest, including the upper barrier, the lower barrier, and the organic shales, varied from 6 to 10 percent. The porosity of each formation averaged about 8%. Densities and ultrasonic velocities were used to evaluate dynamic moduli. Over the tested intervals moduli consistently increased with depth. This indicates the possibility of upward migration of an induced fracture. Perforations, therefore, should be limited to the lower portion of the pay sand and it is also advisable to use low injection rates. Of the four fracturing fluids tested, the two code-named Dow II and Hal I caused, respectively, the least amount of matrix permeability damage to the organically lean and organically rich shales. However, the damage caused by the other fracturing fluids were not severe enough to cause any significant permanent reduction in well productivity. The fracture conductivity tests under the influence of fracturing fluids indicated that Hal I and Dow I caused, respectively, the least amount of multilayered fracture conductivity damage to the organically lean and organically rich samples. For monolayer fracture conductivities Dow I caused least damage to the organically lean shale. With the exception of Dow III all other fluids showed good results in the monolayer tests for organically rich shales. In the situation where both the lean and the rich shales are to be fractured together, the use of either Hal I or Dow I is indicated.

Ahmed, U.; Swartz, G.C.; Scnatz, J.F.

1980-12-01

303

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

304

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

305

Long Period, Long Duration Seismic Events during Hydraulic Fracture Stimulation of a Shale Gas Reservoir  

NASA Astrophysics Data System (ADS)

We report a series of long period and long duration (LPLD) seismic events observed during hydraulic fracturing in a gas shale reservoir located in West Texas. These unusual events, 10-100 seconds in duration, are observed most clearly in the frequency band of 10-80 Hz and are similar in appearance to tectonic tremor sequences which have been observed at depth in several subduction zones and continental strike slip faults. These complex but coherent wave trains have finite move-outs obtained from waveform cross-correlation. The move-out direction of the events confirms that they originate in the reservoir from the area where the fracturing is going on. Clear P- and S-wave arrivals cannot be resolved within the LPLD episodes, but in some cases, small micro-earthquakes occur in the sequences. Whether these micro-earthquakes are causal or coincidental is being studied. It has also been observed that in three contiguous frac-stages, all LPLD events appear to come from two distinct places along one of two hypothetical fracture planes. Interestingly, the stages which have the largest number of LPLD events also have the highest observed pumping pressures during fracturing, the highest density of natural fractures and the greatest number of microearthquakes. One possible explanation of these LPLD events is that the high pore fluid pressure during hydraulic fracturing stimulates slow slip on pre-existing fault planes that are poorly-oriented for slip in the ambient stress field. In the absence of elevated pressure, slip would not be expected on these planes. Slip on these fault planes appears to be occurring because the fluid pressure is close to the magnitude of the least principal stress. We observe a few events between pumping cycles perhaps indicating that once triggered, these planes continue to slip due to the high transient pressure within the fault planes after pumping has stopped.

Das, I.; Zoback, M. D.

2011-12-01

306

Studies of earth stress and hydraulic fracturing with applications in the stimulation of unconventional-gas reservoirs  

NASA Astrophysics Data System (ADS)

The mechanics of hydraulic fracturing for enhanced gas recovery were studied. A minifrac technique for stress measurements at coal mines in the Appalachian and Rocky Mountain regions, to be used to help design fracturing techniques to recover gas from gassy coal beds is discussed. It is indicated that fracture propagation is strongly influenced by existing stresses and that the stress gradient in a nonuniform stress field may stop or turn the fracture. Field evidence shows that anisotropic rock properties due to rock fabric can be a major factor in fracture geometry and in calculated stress values.

Hanson, M.; Towse, D.

1982-09-01

307

Physics-based Modeling of Rock Deformation and Fracturing Induced by Hydraulic Stimulation of Enhanced Geothermal System Reservoirs (Invited)  

Microsoft Academic Search

A key assumption associated with enhanced geothermal system reservoir creation\\/stimulation is that sufficient rock volumes can be hydraulically fractured via both tensile and shear failure, and more importantly by reactivation of naturally existing fractures (by shearing) to create the reservoir. The advancement of enhanced geothermal system greatly depends on our understanding of the dynamics of the intimately coupled rock-fracture-fluid system

H. Huang; R. K. Podgorney; S. Deng

2010-01-01

308

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

2010-04-09

309

Estimation of vertical fracturing from measured elastic moduli  

Microsoft Academic Search

A finely layered medium or a system of parallel fractures in an otherwise homogeneous elastic background renders the medium anisotropic for long wavelengths. The anisotropy increases in complexity as the number of different systems incorporated into the medium increases. Using the group calculus formulation for layered media developed by Schoenberg and Muir, the effects of the individual constituents can be

Julie A. Hood; Michael Schoenberg

1989-01-01

310

Prop Transport in Vertical Fractures: Settling Velocity Correlations  

Microsoft Academic Search

The settling velocity of propping agents is a critical variable in the calculation of proppant distribution in a fracture. Most computer programs available in the industry today base estimates of settling velocity on a Stokes' Law type calculation. We have found that significant deviations from Stokes' Law settling velocities occur in cross-linked fluids and uncrosslinked fluids (concentrations in excess of

P. E. Clark; Nihal Guler

1983-01-01

311

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

312

Vertical tectonic movements of the crust in transform fracture zones of the Central Atlantic  

Microsoft Academic Search

The most significant vertical movements of the oceanic crust in the Central Atlantic are characteristic of transverse ridges\\u000a confined to transform fracture zones. These movements are also recorded in some local depressions of the Mid-Atlantic Ridge\\u000a (MAR) and in older structures of deep-sea basins. The amplitude of such movements substantially exceeds that related to the\\u000a cooling of lithospheric plates. Vertical

A. A. Peive

2006-01-01

313

Fracture patterns and their elastic and hydraulic properties down to 8.5 km depth at the Continental Deep Drillhole (KTB), Germany  

NASA Astrophysics Data System (ADS)

The extensive seismic and petrophysical data set collected at the 9.1 km deep Continental Deep Drillhole (KTB) has been revisited by applying new techniques of data analysis. A complex network of fractures interfering with major fault planes has been identified in the 3D seismic reflection image of by image processing techniques. The analysis concentrates on a 10x10x10 km crustal cube. This seismic reflection data is combined with vertical seismic profiling, petrophysical laboratory and mineralogical data in order to estimate crack porosity values in situ which can then be attributed to the fault and fracture patterns found in the 3D seismic image. The seismic-petrophysical analysis is based on (1) reconstructing the crack-free seismic velocity-depth function from a multi-parametric inversion of seismic velocity data gathered in the laboratory under simulated in situ conditions constrained by a mineralogical depth profile determined from the X-ray diffractometry of drill cuttings, and (2) on evaluating the difference between seismic velocities in situ and reconstructed crack-free velocities in terms of seismic anisotropy and crack porosity. Attributing these crack porosities to the 3D seismic fracture patterns leads to a hydraulic model of the brittle upper crust which can be evaluated by the outcome of the hydraulic injection experiments performed at the KTB site at different depths.

Rabbel, W.; Szalaiova, E.; Iwanowski, K.

2009-12-01

314

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

315

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

316

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.

317

Numerical modelling of shallow hydraulic fracturing: application to the formation of saucer- shaped fractures  

NASA Astrophysics Data System (ADS)

Saucer-shaped intrusions are fundamental intrusion geometries in sedimentary basins, resulting from the intrusion of either magma or fluidized sand. Previous studies have suggested that such saucer-shaped intrusions result from the mechanical interaction between a growing horizontal fracture and the deforming overburden due to the near free surface. In order to quantify and understand the physical processes controlling the emplacement of saucer-shaped intrusions, we resorted to numerical simulations in 2D. We represent the solid by a spring network of molecular dynamic particles and describe the pressure field of the fluid by a poisson equation. The initial geometry of the simulations consisted of a horizontal crack (inner sill) located along a horizontal weakness. A fluid pressure was increased into the crack until it is started propagating horizontally along the weakness. During its propagation, the inner fracture lifted up its overburden and formed a dome, at the rim of which asymmetric stresses generated. The fracture kept propagating until a critical state where the asymmetric stresses were large enough to deflect the fracture tip upward, initiating inclined sheets. Subsequently, the inclined sheets kept propagating and exhibited a typical dip angle. Such numerical simulations allowed us to vary independently the depth of emplacement, the rheological contrast between the horizontal weakness and the surrounding material, the mechanical properties of the overburden, the far-field tectonic state of stress, and the viscosity of the intruding fluid. The final crack shapes were consistent with saucer-shaped intrusions in nature. The results of the simulations showed that the diameter of the inner fracture and the dip angle of the inclined sheets varied systematically. Thus, we found that inner fracture diameter increased and the dip angle of the inclined sheets decreased when (1) the depth of emplacement increased, (2) the rheological contrast between the horizontal weakness increased, (3) the compressional tectonic state of stress increased, and (4) the viscosity of the intruding fluid decreased. By using a dimensional analysis, we will specify the controlling parameters of the system. Our numerical simulations show good agreement to the experiments and that saucer-shaped intrusions typically result from the mechanical interaction between a fluid-filled crack and the Earth surface. Consequently, the saucer shape is the natural shape resulting from the evolution of large shallow flat-lying intrusions in sedimentary basins.

Niebling, M. J.; Galland, O.; Planke, S.; Flekkøy, E.; Malthe-Sorenssen, A.

2008-12-01

318

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

319

Regional evaluation of hydraulic properties in variably fractured rock using a hydrostructural domain approach  

NASA Astrophysics Data System (ADS)

A hydrostructural domain approach was tested and validated in fractured bedrock aquifers of the Gulf Islands, British Columbia (BC), Canada. Relative potential hydraulic properties for three hydrostructural domains in folded and faulted sedimentary rocks were derived using stochastically generated fracture data and hybrid discrete fracture network-equivalent porous media (DFN-EPM) modelling. Model-derived relative potential transmissivity values show good spatial agreement with transmissivity values obtained from pumping tests at selected sites. A spatial pattern of increasing transmissivity towards the southeast along the island chain is consistent between both datasets. Cluster analysis on relative potential permeability values obtained from a larger dataset for the region identified four clusters with geometric means of 9 × 10-13, 4 × 10-13, 2 × 10-13, and 3 × 10-14 m2. The general trend is an increase in relative potential permeability toward the southeast, emulating the trends identified in the site-specific analyses. Relative potential permeability values increase with proximity to the hinge line of a regional northwest-trending asymmetric fault propagation fold structure, and with proximity to superimposed high-angle north- and northeast-trending brittle faults. The results are consistent with documented patterns of structurally controlled fluid flow and show promise for use in regional characterization of fractured bedrock aquifers.

Surrette, M.; Allen, D. M.; Journeay, M.

2008-02-01

320

Energy from True in Situ Processing of Antrim Shale: Preparation of an in Situ Retort Bed by Hydraulic Fracturing.  

National Technical Information Service (NTIS)

Under these specific field conditions, utilization of the natural tendency of the formation to fracture vertically provided the basis for this revised experiment. Observations made during hydrofracturing and permeability testing indicate that a complicate...

C. A. Peil

1980-01-01

321

Finite Element Modeling of the Hydraulic Stimulation Process for Hot Fractured Geothermal Reservoir Construction  

NASA Astrophysics Data System (ADS)

Since the 1970's, a number of research programmes have worked towards developing Hot Dry Rock technology (HDR) for geothermal energy which has been renamed as Hot Fractured Rock (HFR) in Australia. This problem involves the thermal, fluid and mechanical behaviour of geo-materials and induced seismic events, and potential geological perturbations to the geological heat exchanger facility (i.e. the geothermal reservoir) during the construction, production and shutdown phases. The understanding, simulation and prediction of such a multi-scale highly coupled thermo-hydro-mechanical geo-mechanical system are very important in both theory and practical applications. This paper will focus on our current research activity in finite element modeling of the hydraulic stimulation process which is widely applied to construct the HDR/HFR geothermal reservoir system. A 3-dimensional finite element computational model and code for modeling nonlinear frictional contact behaviours between multiple deformable bodies with the arbitrarily-shaped contact element strategy has been developed, which provides a means to simulate interacting fault systems including crustal boundary conditions and various nonlinearities. It has been successfully applied in a wide range of fields and is extended here to simulate the hydraulic stimulation process. The preliminary simulation results on the hydraulic stimulation process demonstrate the stability and usefulness of the algorithm for analyzing hot fractured geothermal reservoir construction. References Xing, H.L., Mora, P. & Makinouchi, A. (2004) Finite element analysis of fault bend influence on stick-slip instability along an intra-plate fault, Pure Appl. Geophys., 161, 2091-2102. Xing, H.L., & Makinouchi, A. (2002) Three dimensional finite element modelling of thermomechanical frictional contact between finite deformation bodies using R-minimum strategy, Computer Methods in Applied Mechanics and Engineering, 191,4193-4214.

Wyborn, D.; Xing, H.; Mora, P.

2005-12-01

322

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

2013-01-01

323

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

324

Determination of Hydraulic Fracture Azimuth by Geophysical, Geological, and Oriented-Core Methods at the Multiwell Experiment Site, Rifle, CO  

Microsoft Academic Search

A comprehensive program for prediction of hydraulic fracture azimuth is being conducted in the tight, lenticular, gas sandstone reservoirs of the Mesaverde Group in the Department of Energy's Multi-Well Experiment near Rifle, Colorado. Methods used in the program can be divided into two groups: 1) indirect, predictive techniques which determine either the principal paleo-stresses or in-situ stresses prior to fracturing

L. W. Teufel; C. M. Hart; A. R. Sattler; J. A. Clark

1984-01-01

325

An application of Bayesian inverse methods to vertical deconvolution of hydraulic conductivity in a heterogeneous aquifer at Oak Ridge National Laboratory  

SciTech Connect

A Bayesian inverse method is applied to two electromagnetic flowmeter tests conducted in fractured weathered shale at Oak Ridge National Laboratory. Traditional deconvolution of flowmeter tests is also performed using a deterministic first-difference approach; furthermore, ordinary kriging was applied on the first-difference results to provide an additional method yielding the best estimate and confidence intervals. Depth-averaged bulk hydraulic conductivity information was available from previous testing. The three methods deconvolute the vertical profile of lateral hydraulic conductivity. A linear generalized covariance function combined with a zoning approach was used to describe structure. Nonnegativity was enforced by using a power transformation. Data screening prior to calculations was critical to obtaining reasonable results, and the quantified uncertainty estimates obtained by the inverse method led to the discovery of questionable data at the end of the process. The best estimates obtained using the inverse method and kriging compared favorably with first-difference confirmatory calculations, and all three methods were consistent with the geology at the site.

Fienen, Michael [ORNL; Kitanidis, Peter K. [Stanford University; Watson, David B [ORNL; Jardine, Philip M [ORNL

2004-01-01

326

Spalling and the development of a hydraulic-fracturing strategy for coal. Annual report, October 1989September 1990  

Microsoft Academic Search

Laboratory hydraulic fracturing experiments were performed on coal blocks from a mine near Marion Center, PA, in order to identify the responsible mechanisms for the high treatment pressures in coal. Tests were performed on saturated as well as unsaturated blocks containing lined and unlined wellbores. Wellbore lining would prevent pore pressure buildup around the wellbore; it would also prevent blockage

M. Khodaverdian; J. D. McLennan; A. H. Jones

1990-01-01

327

Investigation on the Accuracy and Reliability of in-Situ Stress Measurements Using Hydraulic Fracturing in Perforated Cased Holes.  

National Technical Information Service (NTIS)

At present, the only viable technique for accurately measuring stresses at depth in a borehole is hydraulic fracturing. These have been termed microfracs because very small amounts of fluid are injected at low flow rates into the formation. When the well ...

N. R. Warpinski

1983-01-01

328

Balancing the Need for Energy and Clean Water: The Case for Applying Strict Liability in Hydraulic Fracturing Suits  

Microsoft Academic Search

Hydraulic fracturing is a process used to extract natural gas from shale formations. This process has been used commercially since the 1940s, but has recently become prevalent as more shale formations have been discovered, specifically the Marcellus Shale formation in Pennsylvania. Although natural gas is a relatively clean source of domestic energy, there have been numerous allegations of water contamination

Hannah Coman

2012-01-01

329

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

330

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

331

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

332

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

333

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...

334

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.

2011-01-03

335

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

336

An in vitro study of the fracture resistance and the incidence of vertical root fracture of pulpless teeth restored with six post-and-core systems  

Microsoft Academic Search

Statement of problem. Posts and cores are often required with pulpless teeth to provide retention and resistance form for complete crowns. Nevertheless, conventional posts may increase the potential for root fracture. Purpose. This study compared the resistance to vertical root fracture of extracted teeth treated with post-core systems that were modified with polyethylene woven fibers (Ribbond) with those treated with

Sonthi Sirimai; Douglas N. Riis; Steven M. Morgano

1999-01-01

337

Aligned vertical fractures, HTI reservoir symmetry, and Thomsenseismic anisotropy parameters for polar media  

SciTech Connect

Sayers and Kachanov (1991) defined crack-influence parameters that are shown to be directly related to Thomsen (1986) weak-anisotropy seismic parameters for fractured reservoirs when the crack/fracture density is small enough. These results are then applied to the problem of seismic wave propagation in polar (i.e., non-isotropic) reservoirs having HTI seismic wave symmetry due to the presence of aligned vertical fractures and resulting in azimuthal seismic wave symmetry at the earth's surface. The approach presented suggests one method of inverting for fracture density from wave-speed data. It is also observed that the angular location {theta}{sub ex} of the extreme value (peak or trough) of the quasi-SV-wave speed for VTI occurs at an angle determined approximately by the formula tan{sup 2} {theta}{sub ex} {approx_equal} tan {theta}{sub m} = [(c{sub 33} - c{sub 44})/(c{sub 11}-c{sub 44})]{sup 1/2}, where {theta}{sub m} is an angle determined directly (as shown) from the c{sub ij} elastic stiffnesses, whenever these are known from either quasi-static or seismic wave measurements. Alternatively, {theta}{sub ex} is given in terms of the Thomsen seismic anisotropy parameters by tan {theta}{sub ex} {approx_equal} ([v{sub p}{sup 2}(0)-v{sub s}{sup 2}(0)]/[(1 + 2{epsilon})v{sub p}{sup 2}(0)-v{sub s}{sup 2}(0)]){sup 1/4}, where {epsilon} = (c{sub 11}-c{sub 33})/2c{sub 33}, v{sub p}{sup 2}(0) = c{sub 33}/{rho}, and v{sub s}{sup 2}(0) = c{sub 44}/{rho}, with {rho} being the background inertial mass density. The axis of symmetry is always treated here as the x{sub 3}-axis for either VTI symmetry (due, for example, to horizontal cracks), or HTI symmetry (due to aligned vertical cracks). Then the meaning of the stiffnesses is derived from the fracture analysis in the same way for VTI and HTI media, but for HTI the wave speeds relative to the earth's surface are shifted by 90{sup o} in the plane perpendicular to the aligned vertical fractures. Skempton's (1954) coefficient is used as a general means of quantifying the effects of fluids inside the fractures. Explicit formulas for Thomsen's parameters are also obtained for either drained or undrained fractures resulting in either VTI or HTI symmetry of the reservoir.

Berryman, James G.

2007-12-12

338

Acoustic emission monitoring of hydraulic fracturing laboratory experiment with supercritical and liquid CO2  

NASA Astrophysics Data System (ADS)

Carbon dioxide (CO2) is often used for enhanced oil recovery in depleted petroleum reservoirs, and its behavior in rock is also of interest in CO2 capture and storage projects. CO2 usually becomes supercritical (SC-CO2) at depths greater than 1,000 m, while it is liquid (L-CO2) at low temperatures. The viscosity of L-CO2 is one order lower than that of normal liquid water, and that of SC-CO2 is much lower still. To clarify fracture behavior induced with injection of the low viscosity fluids, we conducted hydraulic fracturing experiments using 17 cm cubic granite blocks. The AE sources with the SC- and L-CO2 injections tend to distribute in a larger area than those with water injection, and furthermore, SC-CO2 tended to generate cracks extending more three dimensionally rather than along a flat plane than L-CO2. It was also found that the breakdown pressures for SC- and L-CO2 injections are expected to be considerably lower than for water.

Ishida, Tsuyoshi; Aoyagi, Kazuhei; Niwa, Tomoya; Chen, Youqing; Murata, Sumihiko; Chen, Qu; Nakayama, Yoshiki

2012-08-01

339

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

NASA Astrophysics Data System (ADS)

Quantification of the recharge in fractured aquifers is particularly challenging because of the multiscale heterogeneity and the range of temporal scales involved. Here we investigate the hydraulic response to recharge of a fractured aquifer, using a frequency domain approach. Transfer functions are calculated in a range of temporal scales from 1 day up to a few years, for a fractured crystalline-rock aquifer located in Ploemeur (S Brittany, France), using recharge and groundwater level fluctuations as input and output respectively. The spatial variability of the response to recharge (characteristic response time, amplitude, temporal scaling) is analyzed for 10 wells sampling the different compartments of the aquifer. Some of the transfer functions follow the linear reservoir model behavior. On the contrary, others display a temporal scaling at high frequency that cannot be represented by classic models. Large-scale hydraulic parameters, estimated from the low-frequency response, are compared with those estimated from hydraulic tests at different scales. The variability of transmissivity and storage coefficient tends to decrease with scale, and the average estimates converge toward the highest values at large scale. The small-scale variability of diffusivities, which implies the existence of a range of characteristic temporal scales associated with different pathways, is suggested to be at the origin of the unconventional temporal scaling of the hydraulic response to recharge at high frequency.

JiméNez-MartíNez, JoaquíN.; Longuevergne, Laurent; Borgne, Tanguy; Davy, Philippe; Russian, Anna; Bour, Olivier

2013-05-01

340

Geological and petrological considerations relevant to the disposal of radioactive wastes by hydraulic fracturing: An example at the US Department of Energy's Oak Ridge National Laboratory  

NASA Astrophysics Data System (ADS)

At Oak Ridge National Laboratory the Pumpkin Valley Shale is used as a host formation for hydraulic fracturing waste disposal. Determination of the relationship between the distribution of different lithologies and porosity permeability trends within this host formation allows these properties, important to hydraulic fracturing operations, to be related to measurable and mappable geological and petrological parameters. It also permits extrapolation of such patterns to little studied portions of the Pumpkin Valley Shale. Such knowledge better allows for the satisfactory operation and assessment of the hydraulic fracturing at Oak Ridge National Laboratory.

Haase, C. S.

341

Reflection seismic imaging of a hydraulically conductive fracture zone in a high noise area, Forsmark, Sweden  

NASA Astrophysics Data System (ADS)

High resolution reflection seismic methods have proven to be useful tools for locating fracture zones in crystalline rock. Siting of potential high-level nuclear waste repositories is a particularly important application of these methods. By using small explosive sources (15-75 grams), high resolution images of the sub-surface have been obtained in the depth range 100 m to 2 km in Sweden, Canada and elsewhere. Although ambient noise conditions in areas such as the Fennoscandian and Canadian shields are generally low, industrial noise can be high in some areas, particularly at potential sites suitable for repositories, since these are often close to existing infrastructure. In addition, the presence of this infrastructure limits the choice of sources available to the geophysicist. Forsmark, located about 140 km north of Stockholm, is one such potential site where reflection seismics have been carried out. Existing infrastructure includes nuclear reactors for power generation and a low- level waste repository. In the vicinity of the reactors, it was not possible to use an explosive source due to permitting restrictions. Instead, a VIBSIST system consisting of a tractor mounted hydraulic hammer was used in the vicinity of the reactors. By repeatedly hitting the pavement, without breaking it, at predefined sweeps and then stacking the signals, shot records comparable to explosive data could be generated. These shot records were then processed using standard methods to produce stacked sections along 3 profiles within the reactor area. Clear reflections are seen in the uppermost 600 m along 3 of these profiles. Correlation of crossing profiles shows that the strongest reflection (B8) is generated by a gently east-southeast dipping interface. Prior to construction of the reactors, several boreholes were drilled to investigate the bedrock in the area. One of these boreholes was located close to where two of the profiles cross. Projection of the B8 reflection into the borehole shows that the reflection corresponds to a hydraulically conductive fracture zone that was intersected at about 320 m depth.

Juhlin, C.; Stephens, M. B.; Cosma, C.

2007-05-01

342

Seismological Investigation of Crack Formation in Hydraulic Rock Fracturing Experiments and in Natural Geothermal Environments. Progress Report, September 1, 1980-August 31, 1981.  

National Technical Information Service (NTIS)

Progress is reported on the following: interpretation of seismic data from hydraulic fracturing experiments at the Fenton Hill Hot Dry Rock Geothermal Site, interpretation of 3-D velocity anomalies in the western US with special attention to geothermal ar...

K. Aki

1981-01-01

343

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

344

Flow dimension as an indicator of hydraulic behavior in site characterization of fractured rock.  

PubMed

We examine the possibility of using the flow dimension identified from constant pressure injection tests as a tool for characterizing the hydraulic conditions of fractured media. The data comes from a low-conductivity crystalline rock site, from depths of up to 450 m, and is obtained with 2 m and 10 m measurement scales. In the analysis, the general solution for n-dimensional flow by Barker (1988) is applied. The results show that the most prominent characteristics of the medium can be identified; that is, linear and sublinear flow dimensions as distinguished from dimensions higher than two. In many cases, however, there is significant difficulty in distinguishing the dimensions n = 2, 2.5, and 3 from each other. This is usually because of the experimental difficulties in achieving the ideal conditions required by the theory during the early part of the experiment. In such cases, a full flow curve is not available for the type-curve fitting. In the nonunique cases the higher dimensions typically correspond to higher, sometimes unrealistically high, values of specific storage and to the less reliable and less representative early part of the experiment. Therefore, most of the dimensions in categories n = 3 can be excluded, thus leaving the majority observations in the categories of n = 2 and n = 2-2.5. The dominance of dimension n = 2 is more pronounced for data related to fracture zones in comparison to that related to "average" rock, in particular in the 2 m scale data. The proportion of low (n < 1.5) flow dimensions is small, but for the 10 m scale data it is relatively higher at greater depths and corresponds to lower conductivities. For the smaller 2 m scale data, the low dimensions are not linked to greater depths or systematically smaller conductivities, giving preliminary indication of different flow dimension behavior for the two different scales. PMID:12772826

Kuusela-Lahtinen, A; Niemi, A; Luukkonen, A

345

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.

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

2011-01-01

346

Determination of subsurface distance between vertical parallel natural fractures based on core data  

SciTech Connect

The author presents a simplified method to estimate subsurface distance between vertical parallel fractures based on core analysis and the binomial theorem. The geologic model used in this paper is identical to the one presented by Narr and Lerche in 1984. Required input data include core diameter (D), thickness of each bed intercepted by the core (T), angle between core axis and fractures (..beta..), and angle between core axis and bedding (theta). The method is corroborated with the use of outcrop data previously published by Narr and Lerche in 1984. The approach is illustrated with a step-by-step example, which easily can be reproduced with a hand-held calculator by the practicing geologist. 8 figures, 6 tables.

Aguilera, R.

1988-07-01

347

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

348

Transient gas or liquid flow along a preexisting or hydraulically-induced fracture in a permeable medium  

SciTech Connect

Similarity solutions are derived for the trasient two-dimensional flow of a gas or liquid along an isolated fracture in a permeable medium. The driving pressure at the fracture inlet is constant, and the confining stress is uniform. Two different cases are considered, pre-existing fractures with uniform aperture as well as hydraulic fractures with a variable aperture proportional to the local overpressure (fluid pressure less confining stress). The evolution of the pressure distribution is described by a set of four asymptotic solutions, each having a self-similar form. At early times the flow in the fracture is turbulent, and Darcian seepage losses into the porous surroundings are negligible. At late times the flow in the fracture is laminar, and seepage losses become a dominant consideration. At intermediate times there are two alternative asymptotes, depending upon physical parameters. The mathematical model also describe the flow along a fracture which is fulled with high-permeability porous material as well as the flow in an assemblage of porous blocks. 19 refs., 10 figs.

Nilson, R.H.; Morrison, F.A. Jr.

1985-05-01

349

Characteristics of microearthquakes accompanying hydraulic fracturing as determined from studies of spectra of seismic waveforms  

SciTech Connect

A study of the spectral properties of the waveforms recorded during hydraulic fracturing earthquakes has been carried out to obtain information about the physical dimensions of the earthquakes. We find two types of events. The first type has waveforms with clear P and S arrivals and spectra that are very similar to earthquakes occurring in tectonic regions. These events are interpreted as being due to shear slip along fault planes. The second type of event has waveforms that are similar in many ways to long period earthquakes observed at volcanoes and is called long period. Many waveforms of these events are identical, which implies that these events represent repeated activation of a given source. We propose that the source of these long period events is the sudden opening of a channel that connects two cracks filled with fluid at different pressures. The sizes of the two cracks differ, which causes two or more peaks to appear in the spectra, each peak being associated with one physical dimension of the crack. From the frequencies at which spectral peaks occur, we estimate crack dimensions of between 3 and 22m. 13 refs., 8 figs.

Fehler, M.; Bame, D.

1985-03-01

350

Experimental Study of the Roles of Mechanical and Hydrologic Properties in the Initiation of Natural Hydraulic Fractures  

NASA Astrophysics Data System (ADS)

Natural hydraulic fractures (NHFs) are inferred to form where pore fluid pressure exceeds the least compressive stress; i.e., where the hydraulic fracture criterion is met. Although it has been shown that mechanical heterogeneities serve as nuclei for NHFs, the relative roles of mechanical anisotropy and hydrologic properties in initiating NHFs in porous granular media have not been fully explored. We designed an experimental protocol that produces a pore fluid pressure high enough to exceed the hydraulic fracture criterion, allowing us to initiate NHFs in the laboratory. Initially, cylindrical samples 13 cm long and 5 cm in diameter are saturated, ?1 is radial, and ?3 is axial. By dropping the end load (?3) and pore fluid pressure simultaneously at the end caps, we produce a large pore fluid pressure gradient parallel to the long axis of the sample. This allows us to meet the hydraulic fracture criterion without separating the sample from its end caps. The time over which the pore fluid remains elevated is a function of hydraulic diffusivity. An initial test with a low diffusivity sandstone produced NHFs parallel to bedding laminae that were optimally oriented for failure. To evaluate the relative importance of mechanical heterogeneities such as bedding versus hydraulic properties, we are currently investigating variably cemented St. Peter sandstone. This quartz arenite exhibits a wide range of primary structures, from well developed bedding laminae to locally massive sandstone. Diagenesis has locally accentuated these structures, causing degree of cementation to vary with bedding, and the sandstone locally exhibits concretions that form elliptical rather than tabular heterogeneities. Bulk permeability varies from k=10-12 m2 to k=10-15 m2 and porosity varies from 5% to 28% in this suite of samples. Variations in a single sample are smaller, with permeability varying no more than an order of magnitude within a single core. Air minipermeameter and tracer tests document this variability at the cm scale. Experiments will be performed with ?3 and the pore pressure gradient both perpendicular and parallel to sub-cm scale bedding. The results of these tests will be compared to those of structurally homogeneous samples and samples with elliptical heterogeneities.

French, M. E.; Goodwin, L. B.; Boutt, D. F.; Lilydahl, H.

2008-12-01

351

Ecological considerations for Project Wagon Wheel and hydraulic fracturing activities. Phase II(b). Annual summary for 1975 and project completion report  

Microsoft Academic Search

Environmental studies conducted by an independent team of scientists for El Paso Natural Gas Company in connection with a proposed nuclear fracturing experiment and two massive hydraulic fracturing experiments, which were designed to test the feasibility of stimulating natural gas flow in sandstone formations of low permeability, are summarized. Studies of vegetation, aquatic, non-domestic mammalian populations, and avian populations are

F. W. Whicker; A. W. Alldredge; H. G. Fisser; W. C. Hanson; G. Post

1976-01-01

352

Our Drinking Water at Risk. What EPA and the Oil and Gas Industry Don't Want Us to Know About Hydraulic Fracturing.  

National Technical Information Service (NTIS)

Hydraulic fracturing is a common technique used to stimulate the production of oil and natural gas. Typically, fluids are injected underground at high pressures, the formations fracture, and the oil or gas flows more freely out of the formation. Some of t...

L. Sumi

2005-01-01

353

Aggregation of vertical flow in the vadose zone with auto- and cross-correlated hydraulic properties  

NASA Astrophysics Data System (ADS)

Quantifying water flow across larger areas of the vadose zone has applications in water resources management and climate modeling. The nonlinearity of unsaturated flow and the variability of vadose zone parameters make it difficult, if not impossible, to accurately simulate near-surface water content and flux with large-scale models. Monte Carlo simulations of one-dimensional infiltration and evaporation were conducted with the Richards equation to simulate moisture content and flux in a heterogeneous field according to the streamtube concept. A set of 126 retention curves and saturated hydraulic conductivities from the UNSODA database was used to generate random fields of hydraulic parameters with pre-defined auto- and cross-correlation. Two stochastic parameters were used: the retention shape factor, ln mn, and either the retention scale parameter ?s or ln hG or the saturated hydraulic conductivity, ln Ks. Infiltration is mostly governed by ln Ks. The evaporative flux is strongly determined by the “structural” parameter ln hG and also by the “textural” parameter ln mn. The water content in the upper part of the soil depends mostly on ln mn and somewhat on ?s. Cross-correlations all resulted in clusters with consistently low or high water contents and moisture fluxes. Aggregation to obtain results at larger scales was done by a posteriori averaging of local results. This procedure is a convenient benchmark for large-scale modeling approaches. In an example of a priori aggregation, effective retention parameters were optimized to synthetic retention curves for the larger pixel scale and subsequently used in the Richards equation. The amount of infiltrated water was overestimated by up to 40%, large parts of the upper profile were erroneously predicted to be saturated. Although effective hydraulic properties have been used successfully in evaporation studies, considerable errors, which increased with pixel size, also occurred for evaporation. The stream tube modeling offers a convenient and accurate, albeit mundane, approach to elucidate the role of hydraulic properties and to obtain large-scale hydrological data.

Leij, Feike J.; Sciortino, Antonella; Haverkamp, Randel; Soria Ugalde, José M.

2007-05-01

354

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

355

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

356

Comparison between laboratory experiments and coupled simulations of saucer-shaped hydraulic fractures in homogeneous brittle-elastic solids  

NASA Astrophysics Data System (ADS)

Hydraulic fractures that grow at shallow depth or, more generally, near a free surface, curve towards the surface to become saucer-shaped. These saucer-shaped hydraulic fractures pose challenges for modeling that include the need to track the evolution of the crack path and to follow two distinct moving boundaries corresponding to the leading edge of the crack and the fluid front. Results from a coupled, implicit time stepping numerical model agree well with detailed laboratory experimental data for fluid-driven cracks in glass and PMMA. Specifically, the model and laboratory results show good agreement for the crack path, the evolution of the fluid and fracture fronts, the crack opening, and the injection fluid pressure. This strong comparison not only demonstrates the viability of the numerical model, but more generally the results demonstrate that considering coupling among fluid flow, elastic deformation, and radially symmetric crack growth captures enough of the relevant physical processes to accurately predict the leading order behavior of the physical system realized in the laboratory using homogeneous brittle-elastic solids.

Bunger, Andrew P.; Gordeliy, Elizaveta; Detournay, Emmanuel

2013-07-01

357

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.

Mireku, A. S.; Romberg, E.; Fouad, A. F.; Arola, D.

2012-01-01

358

Demonstration of Massive Hydraulic Fracturing Piceance Basin, Rio Blanco County, Colorado.  

National Technical Information Service (NTIS)

Demonstration of massive fracturing to provide gas production from tight gas sands in the Piceance Basin was the objective of this jointly funded Mobil DOE project. This effort has been at least partially successful. The uppermost interval fractured, the ...

J. L. Fitch W. L. Medlin M. K. Strubhar

1979-01-01

359

Analysis of Vertical Ground Reaction Force Variables during a Sit to Stand Task in Participants Recovering from a Hip Fracture  

PubMed Central

Background A sit to stand task following a hip fracture may be achieved through compensations (e.g. bilateral arms and uninvolved lower extremity), not restoration of movement strategies of the involved lower extremity. The primary purpose was to compare upper and lower extremity movement strategies using the vertical ground reaction force during a sit to stand task in participants recovering from a hip fracture to control participants. The secondary purpose was to evaluate the correlation between vertical ground reaction force variables and validated functional measures. Methods Twenty eight community dwelling older adults, 14 who had a hip fracture and 14 control participants completed the Sit to Stand task on an instrumented chair designed to measure vertical ground reaction force, performance based tests (Timed up and go, Berg Balance Scale and gait speed) and a self report Lower Extremity Measure. A MANOVA was used to compare functional scales and vertical ground reaction force variables between groups. Bivariate correlations were assessed using Pearson Product Moment correlations. Findings The vertical ground reaction force variables showed significantly higher bilateral arm force, higher uninvolved side peak force and asymmetry between the involved and uninvolved sides for the participants recovering from a hip fracture (Wilks’ Lambda = 3.16, p = 0.019). Significant correlations existed between the vertical ground reaction force variables and validated functional measures. Interpretation Participants recovering from a hip fracture compensated using their arms and the uninvolved side to perform a Sit to Stand. Lower extremity movement strategies captured during a Sit to Stand task were correlated to scales used to assess function, balance and falls risk.

Houck, Jeff; Kneiss, Janet; Bukata, Susan V.; Puzas, J. Edward

2011-01-01

360

A Darcian integral approximation to interblock hydraulic conductivity means in vertical infiltration  

NASA Astrophysics Data System (ADS)

Previous work has demonstrated that using non-Darcian interblock conductivity means in mass-conservative models of unsaturated infiltration can produce mass infiltration errors up to 20 times larger than those that mass conservation corrected. But the method to generate true Darcian means from solutions to elliptic boundary value problems is too computationally intensive to be used effectively in models, especially with variable porous media. A previously introduced piecewise approximation did not estimate Darcian means well near saturation for relations, such as a van-Genuchten form, which curves strongly near saturation. This paper introduces a generally more accurate approximation to Darcian means, the Darcian Integral Mean, using the examples of matrix and fracture flow conductivity relations for Topopah Spring welded volcanic tuff (Yucca Mountain, Nevada, USA). It compares the new approximation to the geometric and arithmetic means for matrix and fracture flow, respectively. Although the new approximation may have significant computational overhead of its own, compared to standard means, as well as imperfections, it offers to other investigators a reasonable tool to examine the properties of Darcian means in running models.

Baker, Donald L.

2000-06-01

361

Groundwater ages in fractured rock aquifers  

NASA Astrophysics Data System (ADS)

In fractured porous media, matrix diffusion processes mean that groundwater ages obtained with environmental tracers usually do not reflect the hydraulic age of the water. The distribution of groundwater ages within these heterogeneous systems will be related to the groundwater velocity within the fractures, but also to the size of the fractures and the geometry of the fracture network, and to the hydraulic properties of the aquifer matrix. In this paper, we present analytical and numerical simulations of environmental tracer concentrations in fractured rock aquifers to examine the effect of changes in aquifer parameters on the tracer distributions. In particular, we show that where horizontal fractures are strongly vertically connected, then it may be reasonable to use one-dimensional models of flow and transport through vertical fractures to represent flow through aquifers containing both horizontal and vertical fractures. The presence of large numbers of horizontal fractures will not cause flow to depart significantly from the one-dimensional approximation. Where a smaller number of horizontal fractures are present, then abrupt decreases in the vertical water velocity can occur, as water is intercepted and diverted laterally. Measurements of 14C, 3H, 36Cl, and chlorofluorocarbons within nested piezometers from the Clare Valley, South Australia, display a number of the features apparent in the generic simulations. The use of a number of different tracers appears to allow some fracture and matrix parameters to be constrained more tightly than might previously have been thought possible.

Cook, P. G.; Love, A. J.; Robinson, N. I.; Simmons, C. T.

2005-07-01

362

Seismic monitoring of hydraulic fracturing: techniques for determining fluid flow paths and state of stress away from a wellbore  

SciTech Connect

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and idependently confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional well logging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we believe that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrincis rock properties.

Fehler, M.; House, L.; Kaieda, H.

1986-01-01

363

Extended analysis of constant-height hydraulic fractures for the estimation of in-situ crack-opening modulus from bottomhole pressure records  

SciTech Connect

Hydraulic fractures created in oil and gas bearing rock formations can be made to propagate for a limited time at approximately constant height if favorable stress, deformation modulus or fracture toughness barriers to height growth exist and if the fracture design is suitably optimized to exploit these favorable conditions and reduce height growth. In this report, a unified theoretical formulation for the Perkins-Kern-Nordgren (PKN) and Christianovitch-Geertsma-De Klerk-Daneshy (CGDD) constant height fracture models is first presented. For a fracture fluid injection rate that varies as an arbitrary power of time, growth laws for fracturing fluid pressure, fracture width, and flow rate are rigorously derived for PKN and CGDD types of fractures. These similarity solutions account for non-Newtonian power-law fluid flow, transient fluid storage and generalized power-law fluid leak-off to the rock formation. They include and extend the results currently available in the literature for PKN and CGDD fractures. The results for PKN and CGDD fractures are then generalized to obtain an approximate hybrid CGDD-PKN fracture model that can be applied to constant height fractures of arbitrary length/height aspect ratio and arbitrary cross-sectional shape. Characteristic times for fracture extension are identified and estimates are given for the transition times when the fracture evolves from a CGDD-type fracture at small aspect ratio to a PKN-type fracture at large aspect ratio. These results are useful for interpreting fracturing data and for designing fractures for crack-opening modulus measurements.

Wijesinghe, A.M.

1987-03-01

364

Estimation of the hydraulic conductivity of a two-dimensional fracture network using effective medium theory and power-law averaging  

NASA Astrophysics Data System (ADS)

Most oil and gas reservoirs, as well as most potential sites for nuclear waste disposal, are naturally fractured. In these sites, the network of fractures will provide the main path for fluid to flow through the rock mass. In many cases, the fracture density is so high as to make it impractical to model it with a discrete fracture network (DFN) approach. For such rock masses, it would be useful to have recourse to analytical, or semi-analytical, methods to estimate the macroscopic hydraulic conductivity of the fracture network. We have investigated single-phase fluid flow through generated stochastically two-dimensional fracture networks. The centers and orientations of the fractures are uniformly distributed, whereas their lengths follow a lognormal distribution. The aperture of each fracture is correlated with its length, either through direct proportionality, or through a nonlinear relationship. The discrete fracture network flow and transport simulator NAPSAC, developed by Serco (Didcot, UK), is used to establish the “true” macroscopic hydraulic conductivity of the network. We then attempt to match this value by starting with the individual fracture conductances, and using various upscaling methods. Kirkpatrick’s effective medium approximation, which works well for pore networks on a core scale, generally underestimates the conductivity of the fracture networks. We attribute this to the fact that the conductances of individual fracture segments (between adjacent intersections with other fractures) are correlated with each other, whereas Kirkpatrick’s approximation assumes no correlation. The power-law averaging approach proposed by Desbarats for porous media is able to match the numerical value, using power-law exponents that generally lie between 0 (geometric mean) and 1 (harmonic mean). The appropriate exponent can be correlated with statistical parameters that characterize the fracture density.

Zimmerman, R. W.; Leung, C. T.

2009-12-01

365

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

366

Impact of microbial activity on the hydraulic properties of fractured chalk  

Microsoft Academic Search

The impact of microbial activity on fractured chalk transmissivity was investigated on a laboratory scale. Long-term experiments were conducted on six fractured chalk cores (20 cm diameter, 23–44 cm long) containing a single natural fracture embedded in a porous matrix. Biodegradation experiments were conducted under various conditions, including several substrate and oxygen concentrations and flow rates. 2,4,6-Tribromophenol (TBP) was used

Shai Arnon; Eilon Adar; Zeev Ronen; Alexander Yakirevich; Ronit Nativ

2005-01-01

367

Demonstration of massive hydraulic fracturing Piceance Basin, Rio Blanco County, Colorado  

Microsoft Academic Search

Demonstration of massive fracturing to provide gas production from tight gas sands in the Piceance Basin was the objective of this jointly funded Mobil DOE project. This effort has been at least partially successful. The uppermost interval fractured, the Ohio Creek formation at 7324 to 7476 ft, appears to be commercially viable. The remaining sequence to total depth of 10,800

J. L. Fitch; W. L. Medlin; M. K. Strubhar

1979-01-01

368

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

Microsoft Academic Search

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

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

2009-01-01

369

Estimation of fracture zone geometry from steady-state hydraulic head data using iterative sequential cokriging  

Microsoft Academic Search

The hydrogeology of fractured crystalline rock is often controlled by a few highly conductive features such as faults and\\/or fractures zones. Accurate modeling of fluid flow and transport in these systems requires that the geometry of these conductive features be characterized explicitly. A new method for estimating the geometry of these features is presented. The method is an extension of

Carl E. Renshaw

1996-01-01

370

Hydraulic characteristics of vertical vortex at hydraulic intakes * * Project supported by the National Natural Science Foundation of China (Grant No. 50379030) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20020610016)  

Microsoft Academic Search

The trace of vertical vortex flow at hydraulic intakes is of the shape of spiral lines, which was observed in the presented experiments with the tracer technique. It represents the fluid particles flow spirally from the water surface to the underwater and rotate around the vortex-axis multi-cycle. This process is similar to the movement of screw. To describe the multi-circle

Yun-liang CHEN; Chao WU; Mao YE; Xiao-ming JU

2007-01-01

371

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

372

In situ oxidation by fracture emplaced reactive solids  

Microsoft Academic Search

In low permeability but naturally fractured media, vertical leaching or volatilization of toxic organic compounds can lead to high exposures and unacceptable human health or environmental risk. A field test was recently completed to evaluate in situ remediation at such sites by using hydraulic fracturing to emplace iron metal (Fe°) and permanganate (KMnOâ) solids in the subsurface to chemically treat

Robert L. Siegrist; Kathryn S. Lowe; D. A. Pickering; L. C. Murdoch; T. L. Case

1999-01-01

373

Influence of the Weak Bedding Plane in Michigan Antrim Shale on Laboratory Hydraulic Fracture Orientation.  

National Technical Information Service (NTIS)

The test results from both phases of the study showed that horizontal fractures were consistently created in samples with a confining (horizontal) stress in excess of 100 psi. Samples subjected to confining stresses less than 25 psi displayed only vertica...

G. L. Blaisdell K. Kim

1979-01-01

374

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

375

The Prediction of Hydraulic Fracture Azimuth Through Geological, Core, and Analytical Studies  

Microsoft Academic Search

Results of 10 different methods for determining the maximum horizontal principal stress direction at the DOE's Multi-Well Experiment site in the Piceance Basin, Colorado show remarkable consistency. The methods included surface geological observations (e.g. fracture mapping, lineament analysis, and faulting), analyses of oriented core from the Multi-Well Experiment (e.g. strain relaxation, differential strain analysis, acoustic velocity anisotropy, natural fractures), and

J. A. Clark

1983-01-01

376

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 less efficient COâ 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.

David S. Schechter

2002-01-01

377

Geologic and engineering parameters used in stimulating tight gas-bearing sandstones by modified hydraulic fracturing techniques: North Douglas Creek Arch field, Colorado  

Microsoft Academic Search

Laboratory and field efforts have been made to improve stimulation treatments in the Mancos B formation within the North Douglas Creek Arch field near Rangely, Colorado. To evaluate these efforts, a combination of core analyses and in-situ stress measurements was used in developing a modified hydraulic fracturing program. Whole core samples were taken from upper and lower boundary lithologies as

M. Holland; U. Ahmed; J. Strawn

1984-01-01

378

Hydraulic fracture model and diagnostics verification at GRI\\/DOE multi-site projects and tight gas sand program support. Final report, July 28, 1993February 28, 1997  

Microsoft Academic Search

The Mesaverde Group of the Piceance Basin in western Colorado has been a pilot study area for government-sponsored tight gas sand research for over twenty years. Early production experiments included nuclear stimulations and massive hydraulic fracture treatments. This work culminated in the US Department of Energy (DOE)`s Multiwell Experiment (MWX), a field laboratory designed to study the reservoir and production

1997-01-01

379

Determination of hydraulic fracture azimuth by geophysical, geological, and oriented core methods at the MultiWell Experiment site, Rifle, Colorado  

Microsoft Academic Search

A comprehensive program for prediction of hydraulic fracture azimuth is being conducted in the tight, lenticular, gas sandstone reservoirs of the Mesaverde Group in the Department of Energy's Multi-Well Experiment near Rifle, Colorado. Methods used in the program can be divided into two groups: (1) indirect, predictive techniques which determine either the principal paleo-stresses or in situ stresses prior to

L. W. Teufel; C. M. Hart; A. R. Sattler; J. A. Clark

1984-01-01

380

Faulting Induced by Forced Fluid Injection and Fluid Flow Forced by Faulting: An Interpretation of Hydraulic-Fracture Microseismicity, Carthage Cotton Valley Gas Field, Texas  

Microsoft Academic Search

We analyzed precisely located microearthquake data detected during five hydraulic fracture treatments in the Carthage gas field of east Texas. The treat- ments were conducted in two adjacent boreholes within interbedded sands and shales of the Upper Cotton Valley formation. The microearthquakes were induced within narrow horizontal bands that correspond to the targeted sandstone layers. Events throughout all the treatments

J. T. Rutledge; W. S. Phillips; M. J. Mayerhofer

2004-01-01

381

Effects of Mechanical and Frictional Rock Properties on Hydraulic Fracture Growth Near Unbonded Interfaces.  

National Technical Information Service (NTIS)

Experiments are being performed to study the growth of hydraulically driven cracks in the vicinity of an unbonded interface in rocks. The materials on either side of the interface may be the same or different. The materials used in these studies are Nugge...

G. D. Anderson

1979-01-01

382

Simulate speleogenesis processes with an approach based on fracturing and hydrogeological processes: effect of various hydraulic boundary conditions  

NASA Astrophysics Data System (ADS)

Several numerical modeling approaches attempted to simulate the processes of karst conduit genesis. These existing methods are mainly based on the physical and chemical laws driving the carbonate dissolution processes (taking account of calcite saturation of the water and the partial pressure of carbon dioxide). As a consequence, these works bring a well-documented knowledge on the kinetics of the carbonate dissolution processes in karst systems. Nevertheless, these models are mainly applied on simplified initial void networks, which do not match the fracturing and geological reality. Considering that the initial geometry of the void network (fractures, bedding planes) would have an influence on the final pattern of the speleological network, taking account of it could improve the understanding of speleogenesis. In the aim to take into account the geometry of the initial void network (fracture networks of several orders), a numerical model is developed, which involves a pseudo-statistic fracturing generator (REZO3D, Jourde 1999, Josnin et al. 2002, Jourde et al. 2002) coupled to a finite element groundwater simulator (GROUNDWATER, F. Cornaton, CHYN, University of Neuchâtel). The principle of the modeling of the genesis of the karst drainage system is based on an analogical empirical polynomial equation considering the pore velocity and the mean age of the water as main parameters. The computation is carried out on the basis of a time step, whose duration depends on the simulated scenario (from 100 to 5000 years). The mean age of the water is used in order to simulate the decrease of the chemical dissolving potential of the water within the aquifer, in contact with the carbonate rock. The first simulator -REZO3D- allows producing three-dimensional discrete fracture networks constituted by plane fractures, whose spatial distribution respects mechanical and statistical laws. These networks are then processed in order to write finite element meshes which constitute the bases of groundwater flow and transport simulations. The polynomial parameters of the equation are calibrated with former speleogenesis studies (Dreybrodt 1996, Dreybrodt et al. 2005, Palmer 1991). The presented study involves two orthogonal families of fractures embedded in a carbonate matrix, in a mono-stratum setting. For each simulation, several settings of boundary conditions are tested, in terms of recharge (diffuse or concentrated, hydraulic head or flux limited) and discharge (spatial position, punctual or diffuse). The results are interpreted in terms of head fields, mean groundwater age distributions and total flow rates as a function of time. The aim is to assess the influence of the hydraulic boundary conditions on the finally obtained morphologies of the karstic networks, and on the velocity of the evolution of the drainage system. Results are discussed and perspectives are given on the application of such model to real case studies.

Lafare, A.; Jourde, H.; Leonardi, V.; Pistre, S.; Dörfliger, N.

2012-04-01

383

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

Microsoft Academic Search

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

Günter Zimmermann; Guido Blöcher; Andreas Reinicke; Wulf Brandt

2011-01-01

384

Hydraulic fracturing model based on a three-dimensional closed form  

SciTech Connect

The numerical model described in this paper was designed to provide a realistic three-dimensional (3D) solution for fracture propagation in minimal computation time. Comparisons with available results show good concordance for a wide range of data. The results of a parametric study are compared with the Nolte analysis of the propagation pressure.

Bouteca, M.J. (Inst. Francais du Petrole (FR))

1988-11-01

385

Organic carbon oxidation induced by large-scale shallow water intrusion into a vertical fracture zone at the Äspö Hard Rock Laboratory (Sweden)  

Microsoft Academic Search

Entrance tunnel construction at the Äspö Hard Rock Laboratory opened a conductive vertical fracture zone at a depth of 70 m on March 13, 1991. Three weeks later a sharp dilution front corresponding to 80% shallow water inflow to the originally saline fracture zone arrived at the entrance tunnel depth. In spite of this large inflow of shallow water, the

Steven Banwart; Eva-Lena Tullborg; Karsten Pedersen; Erik Gustafsson; Marcus Laaksoharju; Ann-Chatrin Nilsson; Bill Wallin; Peter Wikberg

1996-01-01

386

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 third semi-annual technical progress report that consists of application of X-Ray Tomography results to validate our numerical modeling of flow in fractures. Spontaneous imbibition plays a very important role in the displacement mechanism of non-wetting fluid in naturally fractured reservoirs. To quantify this spontaneous imbibition process, we developed a 2D two-phase numerical model. This numerical model was developed because an available commercial simulator cannot be used to model small-scale experiments with different boundary conditions. In building the numerical model, we started with the basic equation of fluid flow and developed a numerical approach of solving the non-linear diffusion saturation equation. We compared our numerical model with the analytical solution of this equation to ascertain the limitations of the assumptions used to arrive at that solution. The unique aspect of this paper is that we validated our model with X-ray computerized tomography (CT) experimental data from a different spontaneous imbibition experiment, where two simultaneously varying parameters of weight gain and CT water saturation were used. This requires us to undertake extensive sensitivity studies on key parameters before a successful match could be obtained. We also successfully captured our own X-ray computerized tomography (CT) laboratory experiment on a fractured core.

David S. Schechter

2003-04-01

387

Geological and petrological considerations relevant to the disposal of radioactive wastes by hydraulic fracturing: an example at the US Department of Energy's Oak Ridge National Laboratory. [Pumpkin Valley shales  

SciTech Connect

At Oak Ridge National Laboratory the Pumpkin Valley Shale is used as a host formation for hydraulic-fracturing waste disposal. Determination of the relationships between the distribution of different lithologies and porosity-permeability trends within this host formation allows these properties, important to hydraulic-fracturing operations, to be related to measurable and mappable geological and petrological parameters. It also permits extrapolation of such patterns to little-studied portions of the Pumpkin Valley Shale. Such knowledge better allows for the satisfactory operation and assessment of the hydraulic fracturing at Oak Ridge National Laboratory.

Haase, C.S.

1982-01-01

388

Hydraulic fracturing to determine the regional in situ stress field, Piceance Basin, Colorado  

Microsoft Academic Search

Using specially designed equipment, the state of stress was determined on a regional scale in the Piceance Oil Shale Basin of NW. Colorado. Seven oil-shale test holes scattered throughout the Piceance Basin were logged with an acoustic borehole televiewer to select unfractured solution-free intervals. Fracture-free intervals, ranging in depth from 60 to 460 m, were isolated between packers and hydraulicaly

J. D. Bredehoeft; R. G. Wolff; W. S. Keys; EUGENE SHUTER

1976-01-01

389

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

Microsoft Academic Search

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

J. H. Williams; F. L. Paillet

2002-01-01

390

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

SciTech Connect

In May and July, 1997, a consortia of operators and service companies conducted a series of hydraulic fracture imaging tests in the Carthage Cotton Valley gas field of East Texas (Walker, 1997). Microseismic data were collected and processed for six hydraulic fracture treatments in two wells (3 completion intervals per well) (Mayerhofer et al., 2000). One well was completed with gel-proppant treatments in which a viscous crosslink gel was injected to entrain high concentrations of sand proppant into formation. The second well was completed using treated water and very low proppant concentrations (waterfracs). Waterfracs have been shown to be just as effective as the conventional gel-proppant treatments in Cotton Valley reservoirs, but at greatly reduced cost. Mayerhofer and Meehan (1998) suggest two possible reasons why waterfracs are successful: (1) Induced shear displacement along natural and hydraulic fractures results in self-propping (shear dilation enhanced by fracture branching, proppant and spalled rock fragments), and (2) Fracture extension and cleanup is easier to achieve with low-viscosity fluids. With improved source location precision and focal mechanism determination (fracture plane orientation and sense of slip), we have reexamined the Cotton Valley data, comparing the seismicity induced by water and gel-proppant treatments at common depth intervals. We have improved the location precision and computed focal mechanism of microearthquakes induced during a series of hydraulic fracture completions within the Cotton Valley formation of East Texas. Conventional gel-proppant treatments and treatments using treated water and very low proppant concentrations (waterfracs) were monitored. Waterfracs have been shown to be just as effective as the conventional gel-proppant treatments in Cotton Valley reservoirs, but at greatly reduced cost (Mayerhofer and Meehan, 1998). Comparison of the seismicity induced by the two treatment types show similar distributions of event locations and focal mechanisms for common depth intervals. We interpret the induced seismicity to be primarily controlled by the natural fracture geometry and independent of treatment design. By implication, we expect the effectiveness of shear-induced fracture propping to be independent of the treatment fluid in Cotton Valley reservoirs.

Rutledge, J. T. (James T.); Phillips, W. S. (William Scott)

2002-01-01

391

Hypothesis combining dilation, natural hydraulic fracturing, and dolomitization to explain petroleum reservoirs in Monterey shale, Santa Maria area, California  

Microsoft Academic Search

Fractured reservoirs in the generally siliceous Monterey shale of the Santa Maria area represent an anomalous lithology and type of fracturing. Some, perhaps all, are not fractured chert but parts of the Monterey embrittled by dolomitization. Reservoir fractures, unlike ubiquitous Monterey fractures, are mostly abundant, disordered, open extension fractures that commonly produce epigenetic, dolomitic breccias. These dolomite-cemented breccias commonly contain

Lowell Redwine

1981-01-01

392

Hydraulic Tomography in Fractured Granite: The Mizunami Underground Research Laboratory Site, Japan  

NASA Astrophysics Data System (ADS)

Two large-scale cross-hole pumping tests were conducted at separate locations in deep boreholes at the Mizunami Underground Research Laboratory (MIU) construction site in central Japan. We analyze the two cross- hole tests using the Transient Hydraulic Tomography (THT) code of Zhu and Yeh [2005] to compute the hydraulic conductivity (K) and specific storage (Ss) distributions, as well as their uncertainties in three-dimensions. The equivalent K and Ss obtained using asymptotic analysis served as the initial parameter estimates for the 3D stochastic inverse modeling effort. Results show several, distinct high K and low Ss zones that are continuous over hundreds of meters, which appear to delineate fault zones and its connectivities. The fault zones imaged through THT correlate well with available geological data and drawdown records. The THT analysis also identified a low K zone which corresponds with a known fault zone trending NNW and has been found to compartmentalize groundwater flow at the site. The results are evaluated through available geological information, drawdown records, arrival times of drawdown in response to pumping, velocities of drawdown pulses, and coseismic groundwater level responses during several large earthquakes.

Illman, W. A.; Liu, X.; Yeh, T.; Ando, K.; Takeuchi, S.; Saegusa, H.

2007-12-01

393

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

SciTech Connect

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

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

1997-08-01

394

Passive characterization of hydrofracture properties using signals from hydraulic pumps  

SciTech Connect

Massive hydraulic fracturing is used to enhance production from the low-permeability diatomite fields of Kern County, CA. Although critical for designing injection and recovery well patterns, the in-situ hydraulic fracture geometry is poorly understood. In 1990, Shell conducted an extensive seismic monitoring experiment on several hydrofractures prior to a steam drive pilot to characterize hydrofracture geometry. The seismic data were recorded by cemented downhole geophone arrays in three observation holes (MO-1, MO-2, and MO-3) located near the hydraulic fracture treatment wells. Using lowpass filtering and moveout analysis, events in the geophone recordings are identified as conical shear waves radiating from tube waves traveling down the treatment well. These events appear to be created by the hydraulic pumps, since their amplitudes are correlated with the injection rate and the wellhead pressure. Conical wave amplitudes are related to the tube wave attenuation in the treatment well and to wave-propagation characteristics of the shear component traveling in the earth. During the main fracturing stage, geophones above the fracture zone for wells MO-1 and MO-2 (both roughly along the inferred vertical fracture plane) exhibited conical-wave amplitude increases that are caused by shear wave reflection/scattering off the top of a fracture zone. From changes in the reflection amplitude as a function of depth, we interpret that the fracture zone initially extends along a confined vertical plane at a depth that correlates with many of the microseismic events. Toward the end of the main fracturing stage, the fracture zone extends upward and also extends in width, although we cannot determine the dimensions of the fracture from the reflection amplitudes alone. For all wells, we observe that the reflection (and what we infer to be the initial fracture) begins during a time period where no marked change in fracture pressure or injection rate or slurry concentration is observed. As the main fracturing stage progressed, we observed a significant decrease in amplitude for geophones below the top of the fracture zone. The attenuation was most pronounced for wells MO-1 and MO-2 (along the fracture plane). However, near the end of the main stage, well MO-3 also exhibited a significant amplitude decrease, suggesting the development of a fractured ''process zone'' around the main fracture plane. In addition, well MO-3 also exhibited an amplitude decrease in an interval well below the initial fracture zone. Both the interval and the direction (toward MO-3) correspond with temperature log increases observed during later steam injection.

Rector III, J.W.; Dong, Q.; Patzek, T.W.

1999-01-02

395

Laboratory studies for the design and analysis of hydraulic fracture stimulations in tight gas reservoirs  

SciTech Connect

Laboratory studies were used as an aid in designing stimulation treatments and to assist in the analysis of production results. These analyses were done in conjunction with coastal zone stimulation operations at the Department of Energy's Multiwell Experiment near Rifle, Colorado. A multitreatment stimulation plan was designed for the coastal zone because of apparent damage to the paludal zone formations in prior stimulation operations. The stimulation plan was made to minimize the use of water-based, gelled fluids. Two small stimulations were performed in the same coastal interval: an unpropped nitrogen gas frac and a propped, nitrogen foam frac. Gas production decreased from that of the gas frac after the nitrogen foam stimulation and formation damage was apparent. The laboratory program was used to (1) aid stimulation design; (2) help eliminate several possible causes of damage such as permeability degradation in the matrix rock, a gel block in the sand pack, proppant effects, or imbibition of brine from workover operations; and (3) examine the more probable causes, damage that may be centered around fluid effects in the natural fracture system. A unique explanation is not possible because there are some aspects of these damage mechanisms that cannot be verified in the laboratory. However, comparable damage mechanisms that have been seen in cracked core are described. Also, other postulated forms of fluid damage are discussed, largely in terms of natural fractures in core in combination with other measured core properties. 37 refs., 1 fig., 8 tabs.

Sattler, A.R.; Hudson, P.J.; Raible, C.J.; Gall, B.L.; Maloney, D.R.

1986-01-01

396

Microearthquake characterisation of an artificially stimulated hydraulic fracture at the Coso geothermal area, California  

NASA Astrophysics Data System (ADS)

The Coso geothermal area, California, has produced hot water and steam for electricity generation for more than 20 years, during which time intense microearthquake activity has occurred in the area, much of it induced by geothermal production. The seismicity is monitored by a high-quality permanent network of three- component digital borehole seismometers operated by the US Navy and supplemented by a ~ 14-station portable array of surface three-component digital instruments. The purpose of the portable stations is to improve seismic monitoring around wells in which fluid injection/hydrofracturing experiments are conducted. The first injection experiment was conducted in well 34-9RD2, on the East Flank of the Coso geothermal area. This well was re-drilled February - March 2005 with the intention of hydrofracturing it by injecting fluids under pressure. Instead, natural fractures were encountered at about 2,660 m depth. Drilling muds entered the fractures, obviating the need to stimulate the well. These mud losses induced a 50-minute swarm of 44 microearthquakes, with magnitudes in the range -0.3 to 2.6. Most of the largest microearthquakes occurred in the first 2 minutes. Accurate relative relocations and moment tensors for the best-recorded subset reveal fine details of the fracture stimulated. This comprised a fault striking at N 20 deg E and dipping at 75 deg to the WNW, which propagated to the NNE and upward. Co-injection focal mechanisms reveal combined crack- opening and shear motion. Stress release and mode of failure differed between the pre-, co- and post-swarm periods. Some post-swarm events involved cavity collapse, suggesting that some of the cavities opened by the fluid injection closed quickly. Stress and mode of failure had not returned to pre-swarm conditions within 1 month following the injection, posing the question of how long stress perturbations persist following a stimulation experiment. This question may be answered by processing data spanning a longer post-injection period, work that is currently in hand and will be reported in this presentation. We will also report on progress in developing a Graphical User Interface to facilitate deriving moment tensors from microearthquakes using amplitude ratios.

Foulger, G. R.; Julian, B. R.; Monastero, F. C.

2006-12-01

397

Estimates of hydraulic properties from a one-dimensional numerical model of vertical aquifer-system deformation, Lorenzi site, Las Vegas, Nevada  

USGS Publications Warehouse

Land subsidence related to aquifer-system compaction and ground-water withdrawals has been occurring in Las Vegas Valley, Nevada, since the 1930's, and by the late 1980's some areas in the valley had subsided more than 5 feet. Since the late 1980's, seasonal artificial-recharge programs have lessened the effects of summertime pumping on aquifer-system compaction, but the long-term trend of compaction continues in places. Since 1994, the U.S. Geological Survey has continuously monitored water-level changes in three piezometers and vertical aquifer-system deformation with a borehole extensometer at the Lorenzi site in Las Vegas, Nevada. A one-dimensional, numerical, ground-water flow model of the aquifer system below the Lorenzi site was developed for the period 1901-2000, to estimate aquitard vertical hydraulic conductivity, aquitard inelastic skeletal specific storage, and aquitard and aquifer elastic skeletal specific storage. Aquifer water-level data were used in the model as the aquifer-system stresses that controlled simulated vertical aquifer-system deformation. Nonlinear-regression methods were used to calibrate the model, utilizing estimated and measured aquifer-system deformation data to minimize a weighted least-squares objective function, and estimate optimal property values. Model results indicate that at the Lorenzi site, aquitard vertical hydraulic conductivity is 3 x 10-6 feet per day, aquitard inelastic skeletal specific storage is 4 x 10-5 per foot, aquitard elastic skeletal specific storage is 5 x 10-6 per foot, and aquifer elastic skeletal specific storage is 3 x 10-7 per foot. Regression statistics indicate that the model and data provided sufficient information to estimate the target properties, the model adequately simulated observed data, and the estimated property values are accurate and unique.

Pavelko, Michael T.

2004-01-01

398

Using environmental tracers to constrain flow parameters in fractured rock aquifers; Clare Valley, South Australia  

NASA Astrophysics Data System (ADS)

In fractured rock aquifers, apparent groundwater ages obtained with environmental tracers (e.g., 14C, CFC-12, and 3H) usually do not represent the hydraulic age of the water. Diffusion of solute between the fractures and matrix results in apparent ages that are greater than hydraulic ages, and that may be different for different tracers. We use approximate analytical solutions and numerical simulations of tracer transport through fractured porous media to illustrate the dependence of 14C and CFC-12 ages and 3H concentrations on fracture and matrix properties. In the Clare Valley, South Australia, environmental tracer data are interpreted in conjunction with hydraulic data to constrain flow parameters in a fractured shale aquifer. Hydraulic conductivity, matrix porosity, fracture spacing, and groundwater age are measured, and a value for matrix diffusion coefficient is assumed. Equations describing tracer distribution and hydraulic properties of the system are solved simultaneously, to yield estimates of fracture aperture, vertical water velocity, and aquifer recharge rate. In particular, the recharge rate is estimated to be approximately 100 mm yr-1. A sensitivity analysis showed that this value is most sensitive to the measured values of matrix porosity and groundwater age, and highly insensitive to the measured hydraulic conductivity and the assumed matrix diffusion coefficient. A major horizontal fracture at 37 m depth intercepts most of the vertical flow. The leakage rate to the deeper flow system is estimated to be less than 0.1 mm yr-1.

Cook, Peter G.; Simmons, Craig T.

399

Two-dimensional deformation of a uniform half-space due to non-uniform movement accompanying a long vertical tensile fracture  

NASA Astrophysics Data System (ADS)

The solution of the static deformation of a homogeneous, isotropic, perfectly elastic half-space caused by uniform movement along a long vertical tensile fracture is well known. In this paper, we study the problem of static deformation of a homogeneous, isotropic, perfectly elastic half-space caused by a non-uniform movement along a long vertical tensile fracture of infinite length and finite depth. Four movement profiles are considered: linear, parabolic, elliptic and cubic. The deformation corresponding to the four non-uniform movement profiles is compared numerically with the deformation due to a uniform case, assuming the source potency to be the same. The equality in source potency is achieved in two ways: One, by varying the depth of fracture and keeping the surface discontinuity constant and the other way, by keeping the depth of fracture constant and varying the surface discontinuity. It is found that the effect of non-uniformity in movement in the near field is noteworthy. The far field is not affected significantly by the non-uniformity in movement. In the first case, horizontal displacement is significantly affected rather than vertical displacement. In the second case, non-uniformity in movement changes the magnitude of the displacement at the surface. Also, the displacements around a long vertical tensile fracture for different movement profiles are plotted in three dimensions.

Rani, Sunita; Verma, Ram Chander

2013-08-01

400

Using inverse modeling of aquifer tests to estimate hydraulic properties and heterogeneity of fractured sedimentary rocks at the former Naval Air Warfare Center, West Trenton, NJ  

NASA Astrophysics Data System (ADS)

At the former Naval Air Warfare Center (NAWC), West Trenton, NJ, inverse modeling of aquifer tests conducted in dipping fractured mudstones of the Newark Basin is used to characterize the heterogeneity distribution of the rocks and to estimate their hydraulic properties. This flow modeling is a first step towards development of transport models to investigate the fate and remediation of extensive chlorinated solvent contamination at the site. Ground water underlying the NAWC flows through shallow weathered rocks and dipping sequences of mudstone beds. Water-level and hydraulic-test data suggest that weathered rocks and bedding plane fractures within fissile and laminated mudstones are the primary pathways for ground-water flow, and that less fractured massive mudstones act as flow barriers. To examine these hypotheses, a MODFLOW-2000 model of flow through the fractured rocks is developed and calibrated to short-term aquifer tests conducted by temporarily turning off the pumps in individual wells of a pump-and-treat system. Within the model domain, the area of interest is 400 m by 700 m in horizontal extent and 100 m deep. Horizontal model layers that are up to 20 m thick represent the weathered rocks, and inclined model layers that vary from about 1 to 14 m thick represent the dipping beds. A set of separate aquifer-test simulations using the same underlying model and parameters is calibrated to water-level rise observations from the tests. Results show that a calibrated model that explicitly represents only the major contrasts in rock properties is consistent with the geologic framework and produces a reasonable fit to the aquifer test data. Estimated hydraulic conductivity values are realistic in comparison to independent field data, and vary by orders of magnitude among the different rock types.

Tiedeman, C. R.

2007-12-01

401

3D model of fracture zones at Soultz-sous-Forêts based on geological data, image logs, induced microseismicity and vertical seismic profiles  

NASA Astrophysics Data System (ADS)

This study presents a new deterministic 3D model of the fracture zones observed in the granitic reservoir of the Soultz European geothermal project. The major fracture zones encountered around 6 wells (4550, EPS1, GPK1, GPK2, GPK3 and GPK4) consist in 53 main structures that are located and characterized in terms of size and orientation: 39 fracture zones, 8 microseismic structures and 6 structures derived from vertical seismic profiles are represented in the 3D model using Discrete Fracture Network tools of the gOcad modelling platform (Paradigm™, Earth Decision™). This work illustrates the complexity of 3D fracture zone correlation and interpretation in crystalline rock masses characterized at meter scale (borehole) and at the reservoir scale (kilometer) thanks to geophysical imaging techniques.

Sausse, Judith; Dezayes, Chrystel; Dorbath, Louis; Genter, Albert; Place, Joachim

2010-07-01

402

Integration of microseismic and other post-fracture surveillance with production analysis: A tight gas study  

Microsoft Academic Search

Quantitative production analysis of tight gas reservoirs has historically been a challenge due to complex reservoir characteristics (ex. lateral and vertical heterogeneity, stress-sensitivity of permeability and porosity), induced hydraulic fracture properties in vertical wells (ex. multi-phase flow, conductivity changes, complex fracture geometries), operational complexities (ex. variable back-pressure, liquid-loading) and data quality (infrequent rate or flowing pressure reporting). All of these

C. R. Clarkson; J. J. Beierle

2011-01-01

403

Detection of fractures within the Soultz-sous-Forêts EGS geothermal reservoir by processing of Vertical Seismic Profile data  

NASA Astrophysics Data System (ADS)

The 4 component multi-source/multi-offset VSP (Vertical Seismic Profile) conducted at the Soultz-sous-Forêts EGS (Enhanced Geothermal System) site in 2007 provides records of seismic waves recorded in the fractured granite basement within wells GPK3 and GPK4. Waves generated at 26 surface positions, located at distances between 500m and 5km from the well head in different azimuths, are recorded by 3 component geophones at depths between 5000m and 3000m with a 20m depth interval. The seismic source is a vibrator emitting a 16s long sweep with frequencies varying linearly between 8 and 88 Hz. Two shot locations were simultaneously recorded, one with an upsweep [8 to 88Hz], the other with a downsweep [88 to 8Hz]. Successive correlation with the two sweeps allows retrieving distinct seismograms for each shot from the mixed raw uncorrelated records. Most records show clear downgoing P and S waves. Detecting waves reflected or diffracted by fractures intersecting the wells requires extracting low amplitude upgoing waves from the dominant downgoing wavefield. However, the up to 30° inclination of the well relative to the vertical and the 60 to 90° dips of the fracture zones make the separation of the different waves complex. The wavefield separation of the vertical geophone component is done in the frequency-wavenumber Fourier domain which separates waves according to their apparent velocity across the receiver antenna. Picking of the first arrival times and shifting times allows aligning predominant P wave downgoing wavefield at constant times, or infinite apparent velocity in Fourier domain. Filtering the infinite apparent velocity attenuates all the waves having the same apparent velocity as the first arrivals. A second filtering at the downgoing S waves velocities is then applied, providing two downgoing wavefields, one for the P waves and the other for the S waves. The residuals correspond to the upgoing wavefield. To reduce the reverberations in the upgoing wavefield, we apply a Wiener deconvolution. Faint coherent waves that may originate from fractures are observed in restricted depth intervals. In order to model the arrival times of the extracted reflections/diffractions at the different shot positions, we need a velocity model of the 1400m thick sedimentary cover. P velocities from VSP data of one shot recorded in well GPK4 in sediments and structural information from geological logs and interpreted surface seismic profiles are used to build an initial 3D model with 3 layers separated by dipping plane interfaces. 3D ray tracing is used to compute first arrival times and adjust our model to the data, by modifying the dip of the interfaces. It is then possible to adjust the upgoing waves arrival times to reflections or diffractions on fractures in the reservoir.

Lubrano Lavadera, P.; Marthelot, J. M.; Zillmer, M.; Cornet, F.

2012-04-01

404

Assessment of preferential flow path connectivity and hydraulic properties at single-borehole and cross-borehole scales in a fractured aquifer  

NASA Astrophysics Data System (ADS)

Preferential flow path connectivity is generally cited to explain scaling effects in hydraulic properties [Hsieh, P.A., 1998. Scale effects in fluid flow through fractured geological media, Scale dependence and scale invariance in hydrology. Cambridge University Press, pp. 335 353; Illman, W.A., in press. Strong evidence of directional permeability scale effect in fractured rock. Journal of Hydrology]. However, this information is rarely available in the field. In this study, we present a characterization of flow paths connectivity at the Plœmeur fractured crystalline aquifer from cross-borehole flowmeter tests. We show that high transmissivity zones are connected over distances of at least 150 m all over the site. In parallel, we synthesize hydraulic properties estimates obtained at this site from field techniques having distinct scales of investigation: single borehole flowmeter experiments, cross borehole flowmeter experiments and long term pumping tests. We find that borehole scale variability of transmissivity estimates vanishes at larger scale and that the transmissivity converges towards the high values of the transmissivity distribution. This effect may be explained by the organization of the flow field in the subsurface, and particularly the good connectivity of the permeable zones all over the site.

Le Borgne, T.; Bour, O.; Paillet, F. L.; Caudal, J.-P.

2006-08-01

405

In Situ Stresses in Borehole Blanche-1/South Australia Derived from Breakouts, Core Discing and Hydraulic Fracturing to 2 km Depth  

NASA Astrophysics Data System (ADS)

The development of Hot-Dry Rock (HDR) geothermal energy in Australia with drillings to some kilometres depth yields an impetus for deep stress logging. For the Olympic Dam HDR-project, borehole Blanche-1 was drilled to almost 2 km depth and provided the possibility to estimate the in situ stresses within the granitic borehole section by the analysis of borehole breakouts and core discing, as well as by hydraulic fracturing combined with acoustic borehole televiewer logging for fracture orientation determination. Although the stress magnitudes derived by the different methods deviate significantly, they clearly indicate for the depth range between 800 and 1,740 m a compressional stress regime of S v ? S h < S H and a consistent East-West orientation of maximum horizontal compression in agreement with existing stress data for Australia. The minor horizontal stress S h derived from the hydraulic fracturing closure pressure values is about equal to the overburden stress and may be regarded as most reliable.

Klee, G.; Bunger, A.; Meyer, G.; Rummel, F.; Shen, B.

2011-09-01

406

Hydraulic fracture model and diagnostics verification at GRI/DOE multi-site projects and tight gas sand program support. Final report, July 28, 1993--February 28, 1997  

SciTech Connect

The Mesaverde Group of the Piceance Basin in western Colorado has been a pilot study area for government-sponsored tight gas sand research for over twenty years. Early production experiments included nuclear stimulations and massive hydraulic fracture treatments. This work culminated in the US Department of Energy (DOE)`s Multiwell Experiment (MWX), a field laboratory designed to study the reservoir and production characteristics of low permeability sands. A key feature of MWX was an infrastructure which included several closely spaced wells that allowed detailed characterization of the reservoir through log and core analysis, and well testing. Interference and tracer tests, as well as the use of fracture diagnostics gave further information on stimulation and production characteristics. Thus, the Multiwell Experiment provided a unique opportunity for identifying the factors affecting production from tight gas sand reservoirs. The purpose of this operation was to support the gathering of field data that may be used to resolve the number of unknowns associated with measuring and modeling the dimensions of hydraulic fractures. Using the close-well infrastructure at the Multiwell Site near Rifle, Colorado, this operation focused primarily on the field design and execution of experiments. The data derived from the experiments were gathered and analyzed by DOE team contractors.

Schroeder, J.E.

1997-12-31

407

Development of the T+M coupled flow-geomechanical simulator to describe fracture propagation and coupled flow-thermal-geomechanical processes in tight/shale gas systems  

NASA Astrophysics Data System (ADS)

We developed a hydraulic fracturing simulator by coupling a flow simulator to a geomechanics code, namely T+M simulator. Modeling of the vertical fracture development involves continuous updating of the boundary conditions and of the data connectivity, based on the finite element method for geomechanics. The T+M simulator can model the initial fracture development during the hydraulic fracturing operations, after which the domain description changes from single continuum to double or multiple continua in order to rigorously model both flow and geomechanics for fracture-rock matrix systems. The T+H simulator provides two-way coupling between fluid-heat flow and geomechanics, accounting for thermo-poro-mechanics, treats nonlinear permeability and geomechanical moduli explicitly, and dynamically tracks changes in the fracture(s) and in the pore volume. We also fully account for leak-off in all directions during hydraulic fracturing.

Kim, Jihoon; Moridis, George J.

2013-10-01

408

Detection and Characterization of Hydraulically Active Fractures in a Carbonate Aquifer: Results from Geophysical and Hydrochemical Measurements Along a 260-m-deep Borehole in the Combioula Geothermal System, Western Swiss Alps  

NASA Astrophysics Data System (ADS)

In mountainous regions, pronounced topography, complex geology, and highly permeable geological formations and/or deep-reaching faults and fractures largely govern the development of deep water circulations. In this context, fractured aquifers are of particular interest and the detection and hydraulic characterization of the fractures is a correspondingly important task. Here, in addition to traditional hydrogeological techniques, borehole geophysical measurements were conducted in a fractured deep carbonate aquifer located in the Combioula geothermal system in the western Swiss Alps. The objective of the study was to detect and characterize the hydraulically active fractures along a 260-m-deep borehole through the integration of a comprehensive suite of geophysical well-log data and hydrochemical analysis. Specifically, we wanted to relate the geophysical signals to the fracture network and to examine the sensitivity of the different methods to the flow of groundwater inside the fractures. Although a number of geophysical borehole logging techniques are known to be sensitive to the presence and physical character of fractures, most methods do not provide information with regard to their hydraulic activity. This problem is potentially alleviated through self-potential (SP) measurements, which exhibit a direct sensitivity to fluid flow. Our results illustrate the potential of SP logging for complementing other geophysical logging techniques for distinguishing between hydraulically active and non-active fractures as well as for determining the flow direction within the fractures. The results further indicate that the hydrochemical evidence proved to be critical for the interpretation of the SP measurements. This work may help to open the door for a quantitative interpretation of SP logs with regard to fracture permeability.

Suski, B.; Ladner, F.; Baron, L.; Vuataz, F.; Holliger, K.

2007-12-01

409

Estimates of vertical hydraulic conductivity and regional ground-water flow rates in rocks of Jurassic and Cretaceous age, San Juan Basin, New Mexico and Colorado  

USGS Publications Warehouse

The San Juan structural basin northwestern New Mexico was modeled in three dimensions using a finite-difference, steady-state model. The modeled space was divided into seven layers of square prisms that were 6 miles on a side in the horizontal directions. In the vertical direction, the layers of prisms ranged in thickness from 300 to 1,500 feet. The model included the geologic section between the base of the Entrada Sandstone and the top of Mesaverde Group. Principal aquifers in this section are mostly confined and include the Entrada Sandstone, the Westwater Canyon Member of the Morrison Formation , and the Gallup Sandstone. Values for vertical hydraulic conductivities from 10 to the minus 12th power to 10 to the minus 11th power feet per second for the confining layers gave a good simulation of head differences between layers, but a sensitivity analysis indicated that these values could be between 10 and 100 times greater. The model-derived steady-state flow was about 30 cubic feet per second. About one-half of the flow was in the San Juan River drainage basin about one-third in the Rio Grande drainage basin, and one-sixth in the Puerco River drainage basin. (USGS)

Frenzel, P. F.; Lyford, F. P.

1982-01-01

410

Using Chemicals to Optimize Conformance Control in Fractured Reservoirs  

SciTech Connect

The objectives of this project are: (1) to develop a capability to predict and optimize the ability of gels to reduce permeability to water more than that to oil or gas, (2) to develop procedures for optimizing blocking agent placement in wells where hydraulic fractures cause channeling problems, and (3) to develop procedures to optimize blocking agent placement in naturally fractured reservoirs. Work was directed at both injection wells and production wells and at vertical, horizontal, and highly deviated wells.

Seright, Randall; Liang, Jenn-Tai; Schrader, Richard; Hagstrom II, John; Wang, Ying; Kumar, Anand; Wavrik, Kathryn

2001-09-07

411

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

Federal Register 2010, 2011, 2012, 2013

...Sherri Comerford, Office of Ground Water and Drinking Water, Environmental Protection Agency...Fracturing Activities Using Diesel Fuels--Draft: Underground Injection...available at this Web site,...

2012-06-18

412

Using reverse vertical seismic profiling (RVSP) to characterise the subsurface fracture system of the Seokmo Island geothermal field, Republic of Korea  

NASA Astrophysics Data System (ADS)

This paper presents a case study of fracture-system interpretation using reverse vertical seismic profiling (RVSP) with seismic reflection, refraction, and borehole televiewer data on Seokmo Island, South Korea. We first extracted fracture locations from a pre-existing image obtained by prestack phase-screen migration of RVSP data, and the strike and dip of each fracture from the borehole televiewer data. We established an initial velocity model using this fracture information and then generated synthetic common-receiver gather data through forward simulation. However, the synthetic data could not sufficiently reflect the characteristics of the field data. To resolve this problem, we added an upper alluvial layer, observed in the surface reflection and refraction data, to the velocity model. To improve the quality of the migrated image of the RVSP field data and the velocity model, we not only reprocessed the RVSP data, but also applied prestack generalized-screen migration, which is more accurate than phase-screen migration in computing steep fractures. The new synthetic data generated from the improved velocity model agreed well with the RVSP field data. As a result, we could describe a markedly improved subsurface structure including fracture locations. The workflow suggested in this study will be helpful for imaging fracture systems in oil and gas reservoirs as well as in geothermal reservoirs.

Kim, Bona; Byun, Joongmoo; Seol, Soon Jee; Park, Kwon Gyu; Lee, Tae Jong

2013-06-01

413

Development of the T+M coupled flow–geomechanical simulator to describe fracture propagation and coupled flow–thermal–geomechanical processes in tight/shale gas systems  

EPA Science Inventory

We developed a hydraulic fracturing simulator by coupling a flow simulator to a geomechanics code, namely T+M simulator. Modeling of the vertical fracture development involves continuous updating of the boundary conditions and of the data connectivity, based on the finite element...

414

Analysis of hydraulic and tracer response tests within moderately fractured rock based on a transition probability geostatistical approach  

Microsoft Academic Search

A transition probability and Markov chain geostatistical approach is applied to synthesize the discrete permeability structure of moderately fractured rock. The approach can infuse either hard or subjective categorical information that is consistent with geological interpretations. The methodology is tested using data collected from the Moderately Fractured Rock (MFR) experiment area of the Underground Research Laboratory (URL) in southeastern Manitoba,

Y.-J. Park; E. A. Sudicky; R. G. McLaren; J. F. Sykes

2004-01-01

415

Hydraulic properties of three types of glacial deposits in Ohio  

USGS Publications Warehouse

The effects of thickness, grain size, fractures, weathering, and atmosphericconditions on vertical ground-water flow in glacial deposits were studied at three sites that represent ground moraine, end moraine, and lacustrine depositional environments. Vertical hydraulic conductivities computed from pumped-well tests were 3.24 x 10-1 to 6.47 x 10-1 ft/d (feet per day) at the site representing end moraine and 1.17 ft/d at the site representing lacustrine deposits. Analysis of test data for the ground moraine site did not yield estimates of hydraulic conductivities, but did indicate that ground water flows through the total thickness of deposits in response to discharge from a lower gravel unit. Vertical hydraulic conductivities computed from pumped-well tests of nested wells and data from drill-core analyses indicate that fractures affect the migration of ground water downward through the glacial deposits at these sites. Flow through glacial deposits is complex; it is controlled by fractures, gram-size distribution, clay content, thickness, and degree of weathering, and atmospheric conditions.

Strobel, M. L.

1993-01-01

416

Transform migration and vertical tectonics at the Romanche fracture zone, equatorial Atlantic  

NASA Astrophysics Data System (ADS)

The Romanche transform offsets the Mid-Atlantic Ridge (MAR) axis by about 950 km in the equatorial Atlantic. Multibeam and high-resolution multichannel seismic reflection surveys as well as rock sampling were carried out on the eastern part of the transform with the R/V Akademik Strakhov as part of the Russian-Italian Mid-Atlantic Ridge Project (PRIMAR). Morphobathymetric data show the existence on the northern side of the transform of a major 800-km-long aseismic valley oriented 10 deg to 15 deg from the active valley; it disappears about 150 km from the western MAR segment. The aseismic valley marks probably the former location of the Romanche transform ('PaleoRomanche') that was active up to roughly 8-10 Ma, when the transform boundary migrated to its present position. A temporary microplate developed during the migration and reorientation of the transform. This microplate changed its sense of motion as it was transferred from the South American to the African plate. Evaluation of the seismic reflection data as well as study of samples of carbonates, ventifact basaltic pebbles and gabbroic, peridotitic and basaltic rocks recovered at different sites on the transverse ridge, suggest that (1) the summit of the transverse ridge was above sea level at and before about 5 Ma; (2) the transverse ridge subsided since then at an average rate 1 order of magnitude faster than the predicted thermal contraction rate; its summit was flattened by erosion at sea level during subsidence; (3) the transverse ridge is an uplifted sliver of lithosphere and not a volcanic constructional feature; and (4) transtensional and transpressional tectonics have affected the transverse ridge. Uplift may have been caused primarily by thrust faulting induced by transpression related to the oblique impact of the lithospheric plate against the former (PaleoRomanche) and the younger transform boundaries, before and during the transition to the present boundary. After migration of the transform boundary to its present position, transpression was replaced by transtension and by subsidence of the transverse ridge. An aseismic axial rift valley impacting against the transform valley about 80 km west of the present RTI suggests eastward ridge jumping and probably followed transform migration. Localized transtension or transpression due to bends in the orientation of the transform may have caused intense although localized vertical movements, such as those that formed an ultradeep (greater than 7800 m) pull-apart basin along the transform valley.

Bonatti, E.; Ligi, M.; Gasperini, L.; Peyve, A.; Raznitsin, Y.; Chen, Y. J.

1994-11-01

417

A study of flow-wetted surface area in a single fracture as a function of its hydraulic conductivity distribution  

NASA Astrophysics Data System (ADS)

The contact area between flowing water and rock—the flow-wetted surface (FWS)—is a main factor controlling the rock-matrix diffusion and sorption of flowing solute in a rock fracture. Flow channeling, therefore, has a strong effect on the retardation of mass transport due to the resulting lower contact area. This work presents a systematic study of the dependency between fracture aperture statistics and FWS in strongly heterogeneous fractures. Particle tracking is used to determine the transversal width of the particle flow lines, FWS, and ? factor, where ? is a variable that has been proposed as controlling tracer retention. The conductivity distribution over the fracture is assumed to be lognormal with standard deviation (?ln K) ranging from 0.23 to 4.61, with correlation lengths from 2% to 18% of the width of the flow domain. Results show a clear dependency between the specific flow-wetted surface (sFWS), defined as FWS divided by the total fracture area, and the standard deviation of the logarithm of fracture conductivity. The behavior is independent of the correlation length for the range of correlation lengths tested. The results are presented in the form of type curves and an empirical equation that provide a simple way to determine the sFWS as a function of ?ln K. This information can then be used to adjust the results of large-scale fracture network simulations by taking into account the effect of single fracture heterogeneity, an effect that is in practice infeasible to directly take into account in large-scale fracture network simulations.

Larsson, Martin; Niemi, Auli; Tsang, Chin-Fu

2012-01-01

418

Constructing Hydraulic Barriers in Deep Geologic Formations  

SciTech Connect

Many construction methods have been developed to create hydraulic barriers to depths of 30 to 50 meters, but few have been proposed for depths on the order of 500 meters. For these deep hydraulic barriers, most methods are potentially feasible for soil but not for hard rock. In the course of researching methods of isolating large subterranean blocks of oil shale, the authors have developed a wax thermal permeation method for constructing hydraulic barriers in rock to depths of over 500 meters in competent or even fractured rock as well as soil. The technology is similar to freeze wall methods, but produces a permanent barrier; and is potentially applicable in both dry and water saturated formations. Like freeze wall barriers, the wax thermal permeation method utilizes a large number of vertical or horizontal boreholes around the perimeter to be contained. However, instead of cooling the boreholes, they are heated. After heating these boreholes, a specially formulated molten wax based grout is pumped into the boreholes where it seals fractures and also permeates radially outward to form a series of columns of wax-impregnated rock. Rows of overlapping columns can then form a durable hydraulic barrier. These barriers can also be angled above a geologic repository to help prevent influx of water due to atypical rainfall events. Applications of the technique to constructing containment structures around existing shallow waste burial sites and water shutoff for mining are also described. (authors)

Carter, E.E.; Carter, P.E. [Technologies Co, Texas (United States); Cooper, D.C. [Ph.D. Idaho National Laboratory, Idaho Falls, ID (United States)

2008-07-01

419

Hydraulic Fracture Stimulation Treatments at East Mesa, Well 58-30; Geothermal Reservoir Well Stimulation Program; Experiment 3 and 4  

SciTech Connect

The tests reported were part of the DOE Geothermal Reservoir Well Stimulation Program. This East Mesa (Imperial Valley, CA) well was successfully stimulated with two fracture treatments, a dendritic fracture and a planar fracture. The natural flow production of the well increased 114 percent, to 197,900 lb/hr. These tests were among the few successful attempts of this program to increase flow from geothermal production wells. The general belief is that these tests worked OK primarily because the formation was sedimentary rock (similar to rock in most oil and gas wells that have been stimulated successfully. Similar tests in geothermal hard rock reservoirs did not work very well. (DJE 2005)

None

1982-02-01

420

Flow logging applied in fractured rocks  

NASA Astrophysics Data System (ADS)

Fractured zones are usually identified by the basic logging methods but the volume of permeable fractures intersecting boreholes is often too small for their identification. Fluid logging measurements can help to localize natural flow and determine hydraulic properties of fractures during the pumping. Borehole flowmeter measurements or fluid logging measurements are conventional methods used for the determination of quantitative parameters of the flowing fluid in boreholes with the goal to estimate hydraulic conductivity of aquifers. With the increasing interest in the research of fractured formations and their hydraulic properties, new field techniques based on the repeated measurement of the vertical velocity in an observation borehole during the short hydraulic test (hydraulic pulse) in an other borehole of the tested locality have been elaborated. There is a tendency to increase the lateral range of investigation, it means to make the cross-hole tests in boreholes with greater distance. Such cross-hole tests need to make the measurement of the induced vertical flow in the observation borehole with high resolution flowmeters able to measure vertical flow velocities in the range 10-4 m/s and the flow rates in the range 10-6 m3/s. The new photometric flowmeter was developed for this purpose. The results of the photometric flowmeter measurements were compared with the fluid logging measurements and with heat-pulse flowmeter measurements. In our contribution examples of the comparison of measurements mentioned above in two boreholes situated in granite massif in the Czech Republic are demonstrated. Boreholes were drilled in the program of Czech state institution SÚRAO (Radioactive Waste Repository Authority). The research project is financially supported by the Grant Agency of the Czech Republic under the No. 208/07/0777.

Urík, J.; Lukeš, J.; Kobr, M.; Mareš, S.; Williams, J. H.

2009-04-01

421

Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site  

SciTech Connect

The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite is the most common secondary mineral occurring in 48 percent of the fractures observed.

Lance Prothro

2008-03-01

422

Control of biologically active degradation zones by vertical heterogeneity: Applications in fractured media. 1998 annual progress report  

SciTech Connect

'The objective of this research is to determine the relationship between biologically active contaminant degradation zones in a fractured, subsurface medium and vertical geological heterogeneities. The research is being performed on samples collected from the Test Area North (TAN) site at the Idaho National Engineering and Environmental Laboratory (INEEL) where a dissolved trichloroethylene (TCE) plume is migrating in the basalts and interbed sediments of the Eastern Snake River Plain (ESRP) aquifer. Results are leading to an enhanced understanding of the constraints placed on the activities and distribution of TCE-degrading organisms by the geochemical and hydrological environment. This understanding allows better decisions to be made regarding the use of remedial technologies such as natural attenuation and in-situ bioremediation at geologically complex waste sites. Through this research, investigations conducted by the DOE Subsurface Science Program at TAN have been extended in order to develop a mechanistic understanding of the coupled geomicrobial and hydrogeochemical processes that are necessary to predict field-scale intrinsic degradation rates of TCE. The research objective is being accomplished by characterizing paired cores and water samples from boreholes located in differing geochemical and flow environments within the plume. Analysis of these samples will allow the determination of the spatial correlation between microbial degradation and preferred flow paths for the contaminant and required electron donors and acceptors. A combination of traditional microbiological methods (e.g., enrichments) and molecular tools are being used to characterize the indigenous microbial communities. This report summarizes work conducted after 1.5 years of a three year project.'

Colwell, F.S.; Smith, R.; McKinley, J.P.; Fredrickson, J.K.; Onstott, T.C.; Reysenbach, A.L.

1998-06-01

423

Monitoring of surface deformation and microseismicity applied to radioactive waste disposal through hydraulic fracturing at Oak Ridge National Laboratory  

SciTech Connect

Low-level liquid nuclear wastes are disposed of at Oak Ridge National Laboratory by the hydrofracture process. Wastes are mixed with cement and other additives to form a slurry that is injected into shale of low permeability at 300 m depth. The slurry spreads radially along bedding plane fractures before setting as a grout. Different methods for monitoring the location and behavior of the fractures have been investigated. Radioactive grout sheets can be located by gamma-ray logging of cased observation wells. Two other methods are based on the fact that the ground surface is deformed by the injection. The first entails surface leveling of a series of benchmarks; uplift up to 2.5 cm occurs. The second method involves use of tiltmeters that are sensitive and measure ground deformation in real time during an injection. Both methods show subsidence during the weeks following an injection. Interpretive models for the tiltmeter data are based on the elastic response of isotropic and anisotropic media to the inflation of a fluid-filled fracture. A fourth monitoring method is based on microseismicity. Geophone arrays were used to characterize the fract