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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

Hydraulic fracturing  

E-print Network

Hydraulic fracturing (also hydrofracturing, hydrofracking, fracking, or fraccing) is a well-stimulation technique in which rock is fractured by a hydraulically pressurized liquid. Some hydraulic fractures form naturally—certain veins or dikes are examp...

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

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

Microsoft Academic Search

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

David Wallace Hubble

2003-01-01

5

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

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.

1992-06-01

7

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

8

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

E-print Network

is pr sented in Figure 6, Tiie resul ls for the tv!o methods coir!pave favorably. The general trend of the pi-c!ppant bank geometry is s im ! Ia& in both case=- . The slight inexactness is due to the use of different methods of calculatinq fracture... is pr sented in Figure 6, Tiie resul ls for the tv!o methods coir!pave favorably. The general trend of the pi-c!ppant bank geometry is s im ! Ia& in both case=- . The slight inexactness is due to the use of different methods of calculatinq fracture...

Rasor, Robert Winston

2012-06-07

9

Computer simulation of hydraulic fractures  

Microsoft Academic Search

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

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

2007-01-01

10

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

NASA Astrophysics Data System (ADS)

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

Hubble, David Wallace

11

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

Microsoft Academic Search

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

Lawrence Teufel; James Clark

1984-01-01

12

Some Fundamental Mechanisms of Hydraulic Fracturing.  

E-print Network

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

Wu, Ruiting

2006-01-01

13

Study of Nordgren's Equation of Hydraulic Fracturing  

Microsoft Academic Search

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

L. Kemp

1990-01-01

14

Numerical Investigation of Interaction Between Hydraulic Fractures and Natural Fractures  

E-print Network

Hydraulic fracturing of a naturally-fractured reservoir is a challenge for industry, as fractures can have complex growth patterns when propagating in systems of natural fractures in the reservoir. Fracture propagation near a natural fracture (NF...

Xue, Wenxu

2011-02-22

15

Numerical simulation of hydraulic fracturing  

E-print Network

NUMERICAL SIMULATION OF HYDRAULIC FRACTURING A Thesis by JOSEPH BARNES WARNER Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1987 Maj or Subj ect...: Petroleum Engineering NUMERICAL SIMULATION OF HYDRAULIC FRACTURING A Thesis by JOSEPH BARNES WARNER Approved as to style and content by: S. A. Holditch (Chairman of Committee) D. D. Van Fleet (member) J. E. Russell (m be ) W. D. Von onten ( ead...

Warner, Joseph Barnes

2012-06-07

16

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

17

Simulation of Hydraulic Fractures and their Interactions with Natural Fractures  

E-print Network

Modeling the stimulated reservoir volume during hydraulic fracturing is important to geothermal and petroleum reservoir stimulation. The interaction between a hydraulic fracture and pre-existing natural fractures exerts significant control...

Sesetty, Varahanaresh

2012-10-19

18

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

19

Hydraulic Fracture: multiscale processes and moving  

E-print Network

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

Peirce, Anthony

20

Interpretation of a hydraulic fracturing experiment, Monticello, South Carolina  

SciTech Connect

Pressure transient data from a hydraulic fracturing experiment have been analyzed using a numerical model. Several system parameters and their sensitivities were evaluated, assuming a vertical, penny-shaped fracture geometry. Although the best-fit parameters may not constitute a unique set, they do appear credible from what a current field experience would indicate. It was found that the injection pressure transient is sensitive to initial fracture apeture, fracture stiffness, minimum horizontal stress, rock toughness, and host-rock permeability.

Narasimhan, T.N.; Palen, W.A.

1981-05-01

21

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

22

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

E-print Network

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

Reynolds, Harris Allen

2012-01-01

23

Acoustic Character Of Hydraulic Fractures In Granite  

E-print Network

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

Paillet, Frederick I.

1983-01-01

24

Hydraulic fracturing of jointed formations  

SciTech Connect

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 m/sup 3/ 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, to the reservoir, as well as 11 surface seismometers. The large volume of rock over which the microearthquakes were distributed indicates a mechanism of hydraulic stimulation which is at odds with conventional fracturing theory, which predicts failure along a plane which is perpendicular to the least compressive earth stress. A coupled rock mechanics/fluid flow model provides much of the explanation. Shear slippage along pre-existing joints in the rock is more easily induced than conventional tensile failure, particularly when the difference between minimum and maximum earth stresses is large and the joints are oriented at angles between 30 and 60 degrees to the principal earth stresses, and a low viscosity fluid like water is injected. Shear slippage results in local redistribution of stresses, which allows a branching, or dendritic, stimulation pattern to evolve, in agreement with the patterns of microearthquake locations. These results are qualitatively similar to the controversial process known as ''Kiel'' fracturing, in which sequential injections and shut-ins are repeated to create dendritic fractures for enhanced oil and gas recovery. However, we believe that the explanation is shear slippage of pre-existing joints and stress redistribution, not proppant bridging and fluid blocking as suggested by Kiel. 15 refs., 10 figs.

Murphy, H.D.; Fehler, M.C.

1986-01-01

25

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

26

DEMONSTRATION BULLETIN: HYDRAULIC FRACTURING OF CONTAMINATED SOIL  

EPA Science Inventory

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

27

Acoustic-emission monitoring during hydraulic fracturing  

SciTech Connect

This paper reports that microseismic events or acoustic emissions associated with hydraulic fracturing are recorded with a borehole seismic tool in a deviated well during multirate injection, shut-in, and flowback. The event locations indicate that fracture orientation, length, and height are compatible with regional stress directions and estimates of the fracture size that are based on pressure decline.

Stewart, L. (Schlumberger-Doll Research (US)); Cassell, B.R. (Schlumberger Wireline Services (US)); Bol, G.M. (Nederlanse Aardolie Mij. B.V. (NL))

1992-06-01

28

Hydraulic Fracturing and the Environment  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

29

Geomechanical review of hydraulic fracturing technology  

E-print Network

Hydraulic fracturing as a method for recovering unconventional shale gas has been around for several decades. Significant research and improvement in field methods have been documented in literature on the subject. The ...

Arop, Julius Bankong

2013-01-01

30

Interaction between Injection Points during Hydraulic Fracturing  

E-print Network

We present a model of the hydraulic fracturing of heterogeneous poroelastic media. The formalism is an effective continuum model 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. As an application of the formalism, we study the geomechanical stress interaction between two injection points during hydraulic fracturing (hydrofracking) and how this interaction influences the fracturing process. For injection points that are separated by less than a critical correlation length, we find 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

2012-01-01

31

Numerical model of massive hydraulic fracture. Final report. [SYMFRAC1  

SciTech Connect

This project has involved development of a hydraulic fracture simulator which calculates fracture height as a function of distance from the wellbore in a situation in which a payzone is bounded by two zones in which the minimum in-situ stress is higher (the fracture is vertical). The fracture must be highly elongated (length/height ratio approximately greater than 4) and variations in elastic modulus across zones are ignored. First, we describe the leakoff and spurt loss calculations employed in the modeling. Second, we discuss a revised version of the vertically symmetric simulator (bounding zone stresses equal). The addition of non-Newtonian flow and leakoff (including spurt loss) is described in detail. An illustrative result is given. Third, we describe in detail the vertically asymmetric simulator (bounding zone stresses not equal). To illustrate the last results, we present design calculations for a 30,000 gallon fracture, which was the first stimulation in the Multi-Well Experiment. The 80 ft fracture interval in the Paludal zone has at its upper edge a 520 psi stress contrast, and at its lower edge a 1195 psi contrast. Computed fracture height growth above and below the perforated interval, bottomhole pressure, and width profiles in vertical sections are displayed. Comparison is made with diagnostic measurements of fracture length, height, and bottomhole pressure. The appropriate computer codes are included in this report. 21 references, 11 figures, 4 tables.

Palmer, I.D.; Craig, H.R.; Luiskutty, C.T.

1985-03-01

32

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

33

Universal asymptotic umbrella for hydraulic fracture modeling  

E-print Network

The paper presents universal asymptotic solution needed for efficient modeling of hydraulic fractures. We show that when neglecting the lag, there is universal asymptotic equation for the near-front opening. It appears that apart from the mechanical properties of fluid and rock, the asymptotic opening depends merely on the local speed of fracture propagation. This implies that, on one hand, the global problem is ill-posed, when trying to solve it as a boundary value problem under a fixed position of the front. On the other hand, when properly used, the universal asymptotics drastically facilitates solving hydraulic fracture problems (both analytically and numerically). We derive simple universal asymptotics and comment on their employment for efficient numerical simulation of hydraulic fractures, in particular, by well-established Level Set and Fast Marching Methods.

Linkov, Aleksandr M

2014-01-01

34

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

35

Coupling schemes for modeling hydraulic fracture propagation using the XFEM  

E-print Network

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

Peirce, Anthony

36

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS?  

E-print Network

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

Paris-Sud XI, Université de

37

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

38

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.

Laue, M.L.

1999-11-01

39

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

40

Effectiveness of microseismic monitoring for optimizing hydraulic fracturing in California  

E-print Network

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

Alampi, Ann M

2014-01-01

41

Hydraulic conductivity of rock fractures  

Microsoft Academic Search

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

Robert W. Zimmerman; Gudmundur S. Bodvarsson

1996-01-01

42

Characterizing the dynamic behavior of hydraulically-induced fracture networks associated with hydraulic fracture stimulations (Invited)  

NASA Astrophysics Data System (ADS)

Seismic Moment Tensor Inversion (SMTI) analysis of microseismicity recorded with multi-well multi-array configurations allows for the potential determination of fracture growth, both spatially and temporally away from a treatment well, as well as the identification of fracture interactions within the reservoir. Based on these analyses, it may be possible to identify the role of pre-existing fracture networks in fracture development as well as, for example, failure type, fracture connectivity, and fracture intensity. Here, we present our observations based on evaluating event sequences associated with multiple injection programs in shale plays throughout North America. In our analysis we identify that, generally, local hydraulically induced variations in the stress-strain field during stimulation result in mixed-mode shear/tensile failures along predominantly pre-existing fractures/joints emplaced during current- and paleo-stress regimes rather than in the creation of new fractures. Away from treatment intervals, failures tend to be dominated by shear and are heavily influenced by the regional stress conditions. Utilizing Hudson plots (k-T), it appears that the fracture process can be further broken down into four types of activity relative to the treatment well and the start of the injection, namely initiation/reactivation of fractures (k ~ 0, double couple dominated), breakout into formation (explosive isotropic), progression of fracture from the treatment well (mostly explosive isotropic), and fracture infill behind the fracture front (decreasing k with treatment time, i.e., explosive to implosive). Breakout events comprised of crack-opening type failures followed by closure events close to the treatment well could be considered to be a canonical fracture, and that the observed behavior can be thought of as the superposition of many of these canonical fractures. Based on our observations, we suggest that by mapping these mechanisms, we can begin to delineate the development of hydraulically-induced fracture networks during hydraulic fracture stimulations and further establish the underlying fracturing process.

Urbancic, T.; Baig, A. M.

2013-12-01

43

Linking earthquakes and hydraulic fracturing operations  

NASA Astrophysics Data System (ADS)

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

Balcerak, Ernie

2013-01-01

44

Regulation of Hydraulic Fracturing in California  

E-print Network

RsPeCtive Michael Kiparsky and Jayni Foley Hein #12;Berkeley law | wheeler InstItute for water law & PolIcy at clee2 | Regulation of Hydraulic Fracturing in California Wheeler Institute for Water Law & Policy Center for Law & PolIcy at clee The Wheeler Institute for Water Law & Policy develops innovative law and policy

Kammen, Daniel M.

45

Hydraulic fracture model comparison study: Complete results  

SciTech Connect

Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.

Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)

1993-02-01

46

HYDRAULIC STIMULATION OF NATURAL FRACTURES AS REVEALED BY INDUCED MICROEARTHQUAKES,  

E-print Network

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

47

Modeling Turbulent Hydraulic Fracture Near a Free Surface  

E-print Network

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

48

Role of seepage forces on hydraulic fracturing and failure patterns  

E-print Network

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

Paris-Sud XI, Université de

49

Modeling Turbulent Hydraulic Fracture Near a Free Surface  

E-print Network

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

50

An analytical model for hydraulic fracturing in shallow bedrock formations.  

PubMed

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

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

2011-01-01

51

A PKN Hydraulic Fracture Model Study and Formation Permeability Determination  

E-print Network

Hydraulic fracturing is an important method used to enhance the recovery of oil and gas from reservoirs, especially for low permeability formations. The distribution of pressure in fractures and fracture geometry are needed to design conventional...

Xiang, Jing

2012-02-14

52

Hydraulic fracturing in granite under geothermal conditions  

USGS Publications Warehouse

The experimental hydraulic fracturing of granite under geothermal conditions produces tensile fracture at rapid fluid injection rates and shear fracture at slow injection rates and elevated differential stress levels. A sudden burst of acoustic emission activity accompanies tensile fracture formation whereas the acoustic emission rate increases exponentially prior to shear fracture. Temperature does not significantly affect the failure mechanism, and the experimental results have not demonstrated the occurrence of thermal fracturing. A critical result of these experiments is that fluid injection at intermediate rates and elevated differential stress levels increases permeability by more than an order of magnitude without producing macroscopic fractures, and low-level acoustic emission activity occurs simultaneously near the borehole and propagates outward into the specimen with time. Permeability measurements conducted at atmospheric pressure both before and after these experiments show that increased permeability is produced by permanent structural changes in the rock. Although results of this study have not demonstrated the occurrence of thermal fracturing, they suggest that fluid injection at certain rates in situ may markedly increase local permeability. This could prove critical to increasing the efficiency of heat exchange for geothermal energy extraction from hot dry rock. ?? 1980.

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

1980-01-01

53

Solving vertical and horizontal well hydraulics problems analytically in Cartesian coordinates with vertical and horizontal anisotropies  

NASA Astrophysics Data System (ADS)

SummaryA new generalized three-dimensional analytical solution is developed for a partially-penetrating vertical rectangular parallelepiped well screen in a confined aquifer by solving the three-dimensional transient ground water flow differential equation in x- y- z Cartesian coordinates system for drawdown by taking into account the three principal hydraulic conductivities ( Kx, Ky, and Kz) along the x- y- z coordinate directions. The fully penetrating screen case becomes equivalent to the single vertical fracture case of Gringarten and Ramey (1973). It is shown that the new solution and Gringarten and Ramey solution (1973) match very well. Similarly, it is shown that this new solution for a horizontally tiny fully penetrating parallelepiped rectangular parallelepiped screen case match very well with Theis (1935) solution. Moreover, it is also shown that the horizontally tiny partially-penetrating parallelepiped rectangular well screen case of this new solution match very well with Hantush (1964) solution. This new analytical solution can also cover a partially-penetrating horizontal well by representing its screen interval with vertically tiny rectangular parallelepiped. Also the solution takes into account both the vertical anisotropy ( azx = Kz/ Kx) as well as the horizontal anisotropy ( ayx = Ky/ Kx) and has potential application areas to analyze pumping test drawdown data from partially-penetrating vertical and horizontal wells by representing them as tiny rectangular parallelepiped as well as line sources. The solution has also potential application areas for a partially-penetrating parallelepiped rectangular vertical fracture. With this new solution, the horizontal anisotropy ( ayx = Ky/ Kx) in addition to the vertical anisotropy ( azx = Kz/ Kx) can also be determined using observed drawdown data. Most importantly, with this solution, to the knowledge of the author, it has been shown the first time in the literature that some well-known well hydraulics problems can also be solved in Cartesian coordinates with some additional advantages other than the conventional cylindrical coordinates method.

Batu, Vedat

2012-01-01

54

Fracturing Demonstration using a Hydraulic Press  

NSDL National Science Digital Library

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

Harris, James B.

55

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions  

E-print Network

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

Peirce, Anthony

56

Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions  

E-print Network

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

Peirce, Anthony

57

Application of hydraulic fracturing technologies to the shallow Telisa formation  

SciTech Connect

This paper describes the changes that have been made to the stimulation treatments in the Telisa formation over the past year. The Telisa formation in the South Balam Field is a shallow ({+-} 600 feet), high permeability (10--100 md), laminated sandstone reservoir. The South Balam Field is located near the large Duri Field in central Sumatra. Hydraulic fracturing was initiated in the Telisa formation at South Balam Field in 1990. due to the shallow depth of Telisa formation surface treating pressure are typically 400 to 600 psi. These low pressure make pressure analysis very difficult. In many instances only 100 psi of net pressure is seen during the treatments. It is difficult to measure fluctuations in net pressure using only surface data. This has prompted the use of bottom hole pressure recorders with surface read-out which are more accurate and have higher resolution. The pressure recorders are hung inside tubing approximately 100 feet above the perforations, which eliminates pipe friction during the treatment analysis. The treatment are pumped down the annulus. Minifracs were performed and analyzed using bottom hole pressure data to determine fluid efficiency, fracture closure pressure, and leakoff characteristics. Results of these tests have resulted in job modifications regarding pad and treatment sizes. History matching of treatment pressures, both post-frac and in real-time, have been performed using a hydraulic fracture simulator to determine created fracture geometries. Low level radioactive isotope tracer material was used to tag the treatments for determining the fluid and proppant distribution throughout the pay interval. The accumulation of this data indicates that hydraulic fractures in the Telisa formation are not horizontal, as expected for this shallow depth, but are vertical in orientation. This paper indicates techniques and results which can be applied to other shallow high permeability sandstone reservoirs.

Poerwanto, J.H.; Sugembong, C.F.; Bagzis, J.M.; Martinez, A.D.

1995-10-01

58

Experimental investigation of geomechanical aspects of hydraulic fracturing unconventional formations.  

E-print Network

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

Alabbad, Emad Abbad

2014-01-01

59

Vertical root fractures and their management  

PubMed Central

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

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

2014-01-01

60

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

61

Hydraulic Fracture Monitoring: A Jonah Field Case Study  

E-print Network

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

Seher, T.

2011-01-01

62

A Study of Hydraulic Fracturing Initiation in Transversely Isotropic Rocks  

E-print Network

Hydraulic fracturing of transverse isotropic reservoirs is of major interest for reservoir stimulation and in-situ stress estimation. Rock fabric anisotropy not only causes in-situ stress anisotropy, but also affects fracture initiation from...

Serajian, Vahid

2011-10-21

63

Calibration of hydraulic and tracer tests in fractured media  

E-print Network

Calibration of hydraulic and tracer tests in fractured media represented by a DFN Model L. D. Donado, X. Sanchez-Vila, E. Ruiz* & F. J. Elorza** * Enviros Spain S.L. ** UPM #12;Fractured Media Water flows through fractures (matrix basically impervious � though relevant to transport) Fractures at all

Politècnica de Catalunya, Universitat

64

A finite element model for three dimensional hydraulic fracturing  

Microsoft Academic Search

This paper is devoted to the development of a model for the numerical simulation of hydraulic fracturing processes with 3d fracture propagation. It takes into account the efects of fluid flow inside the fracture, fluid leak-off through fracture walls and elastic response of the surrounding porous media. Finite element techniques are adopted for the discretization of the conservation law of

Philippe R. B. Devloo; Paulo Dore Fernandes; Sônia M. Gomes; Cedric Marcelo Augusto Ayala Bravo; Renato Gomes Damas

2006-01-01

65

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

Federal Register 2010, 2011, 2012, 2013

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

2013-04-05

66

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

Federal Register 2010, 2011, 2012, 2013

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

2013-09-10

67

Toughness-Dominated Regime of Hydraulic Fracturing in Cohesionless Materials  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

68

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

69

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...

70

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

71

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

72

On equivalence of thinning fluids used for hydraulic fracturing  

E-print Network

The paper aims to answer the question: if and how non-Newtonian fluids may be compared in their mechanical action when used for hydraulic fracturing? By employing the modified formulation of the PKN problem we obtain its simple analytical solutions in the cases of perfectly plastic and Newtonian fluids. Since the results for shear thinning fluids are intermediate between those for these cases, the obtained equation for the fracture length suggests a criterion of the equivalence of various shear thinning fluids for the problem of hydraulic fractures. We assume fluids equivalent in their hydrofracturing action, when at a reference time they produce fractures of the same length. The equation for the fracture length translates the equivalence in terms of the hydraulic fracture length and treatment time into the equivalence in terms of the properties of a fracturing fluid (behavior and consistency indices). Analysis shows that the influence of the consistency and behavior indices on the fracture length, particle v...

Linkov, Alexander

2012-01-01

73

A magnetic method for determining the geometry of hydraulic fractures  

USGS Publications Warehouse

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

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

1976-01-01

74

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

75

Relationship between hydraulic conductivity and fracture properties estimated from packer tests and borehole data in a fractured granite  

Microsoft Academic Search

Hydraulic conductivity is closely related to fracture characteristics like fracture aperture and frequency, fracture length, fracture orientation and angle, fracture interconnectivity, filling materials, and fracture plane features. In this study, water injection tests were conducted at six boreholes of different depths drilled in fractured granite in the Mt. Geumjeong area, Korea. Hydraulic conductivity was calculated using the USBR (United States

Se-Yeong Hamm; MoonSu Kim; Jae-Yeol Cheong; Jung-Yul Kim; Moon Son; Tae-Won Kim

2007-01-01

76

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

77

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

78

Studies investigate effects of hydraulic fracturing  

NASA Astrophysics Data System (ADS)

The use of hydraulic fracturing, also known as fracking, to enhance the retrieval of natural gas from shale has been increasing dramatically—the number of natural gas wells rose about 50% since 2000. Shale gas has been hailed as a relatively low-cost, abundant energy source that is cleaner than coal. However, fracking involves injecting large volumes of water, sand, and chemicals into deep shale gas reservoirs under high pressure to open fractures through which the gas can travel, and the process has generated much controversy. The popular press, advocacy organizations, and the documentary film Gasland by Josh Fox have helped bring this issue to a broad audience. Many have suggested that fracking has resulted in contaminated drinking water supplies, enhanced seismic activity, demands for large quantities of water that compete with other uses, and challenges in managing large volumes of resulting wastewater. As demand for expanded domestic energy production intensifies, there is potential for substantially increased use of fracking together with other recovery techniques for “unconventional gas resources,” like extended horizontal drilling.

Balcerak, Ernie

2012-11-01

79

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

80

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

81

Vertical root fracture: prevalence, etiology, and diagnosis.  

PubMed

A vertical root fracture (VRF) is a frustrating complication that may occur following root canal treatment, and in almost every case leads to the extraction of the affected tooth. This type of fracture is usually diagnosed by secondary symptoms that develop some time after primary treatment, often when prosthodontic restoration has already been completed. The fracture line itself is often not directly visible, and therefore clinical and radiographic signs and symptoms indicate the diagnosis indirectly. Knowledge of the condition and pathogenesis of VRF is required in order to avoid hopeless trials of periodontal and/or endodontic therapy. Several etiologic factors are discussed that make teeth susceptible to VRF, such as the loss of substance due to restorative and endodontic therapy and stress factors associated with root canal debridement, and filling. PMID:23757466

Haueisen, Helga; Gärtner, Kathrin; Kaiser, Lea; Trohorsch, Dominik; Heidemann, Detlef

2013-07-01

82

An iterative calculation for determining formation and fracture properties in hydraulically fractured reservoirs  

E-print Network

AN ITERATIVE CALCULATION FOR DETERMINING FORMATION AND FRACTURE PROPERTIES IN HYDRAULICALLY FRACTURED RESERVOIRS A Thesis by STEPHEN RHETT GIST Submitted to the Graduate College of Texas A R M University In Partial Fulfillment... of the Requirement for the Degree of Master of Science May 1984 Major Subject: Petroleum Engineering AN ITERATIVE CALCULATION FOR DETERMINING FORMATION AND FRACTURE PROPERTIES IN HYDRAULICALLY FRACTURED RESERVOIRS A Thesis by STEPHEN RHETT GIST Approved...

Gist, Stephen Rhett

2012-06-07

83

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

84

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

USGS Publications Warehouse

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

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

2009-01-01

85

Cyclic Steaming of Tar Sands Through Hydraulically Induced Fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms that resulted from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed with numerical modeling. Horizontal fracture radii of 100 ft (30.5 m) and vertical fracture half-lengths of 250 ft (76.2 m) with fracture surface areas of 30,000 to 70,000 sq ft (2787 to 6503 m²) are sufficient to reproduce

J. K. Dietrich

1986-01-01

86

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...

87

Influence of pressure change during hydraulic tests on fracture aperture.  

PubMed

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

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

2013-03-01

88

Computer simulation of hydraulic fracturing in shales--implications on primary migration. [Naturally occurring fracture during sedimentation  

Microsoft Academic Search

Hydraulic tension fractures in a shale layer during sedimentation is simulated using computer techniques. Thickness, hydraulic conductivity, tensile strength of the shale layer, as well as the rate of sedimentation are the prime factors which control hydraulic fracturing. The depth at which fractures form are directly proportional to the hydraulic conductivity and tensile strength, and inversely proportional to the rate

OzKaya

1983-01-01

89

Shear and tension hydraulic fractures in low permeability rocks  

USGS Publications Warehouse

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

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

1977-01-01

90

Estimating the fracture density of small-scale vertical fractures when large-scale vertical fractures are present  

E-print Network

When fractures are vertical, aligned and their dimensions are small relative to the seismic wavelength, the medium can be considered to be an equivalent Horizontal Transverse Isotropic (HTI) medium. However, geophysical ...

Liu, Yuwei

2013-01-01

91

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

USGS Publications Warehouse

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

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

2002-01-01

92

EPA releases progress report on hydraulic fracturing study  

NASA Astrophysics Data System (ADS)

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

Showstack, Randy

2013-01-01

93

An investigation of productivity increases from hydraulic fracturing treatments  

E-print Network

AN INVESTIGATION OF PRODUCTIVITY INCREASES FROM HYDRAULIC FRACTURING TREATMENTS A Thesis b7 Robert Joe Boriskie Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August, 1963 Major Subject: Petroleum Engineering AN INVESTIGATION OF PRODUCTIVITY INCREASES FROM HYDRAULIC FRACTURING TREATMENTS A Thesis Robert Joe Boriskie Approved as to style and content by: Chairman of Committee...

Boriskie, Robert Joe

2012-06-07

94

Studying Hydraulic Fracturing through Time-variant Seismic Anisotropy  

E-print Network

Hydraulic fracturing is an important modern technique of exploiting natural gas and oil, in which a high-pressure liquid mixture is injected into a wellbore to create small fractures in order to release fluids such as natural gas and petroleum...

Liu, Qifan

2013-10-01

95

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

96

Viscous Fluids Provide Improved Results from Hydraulic Fracturing Treatments  

Microsoft Academic Search

Improved recovery of oil and gas is possible with the use of highly viscous fluids in the hydraulic fracturing process. These are water or oil-base gels that help create wider fractures than is possible with the so-called conventional fluids. This allows the placement of additional quantities (concentrations up to 6 lb per gal or more) of highly permeable propping agents

R. B. Rosene; E. F. Shumaker

1971-01-01

97

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

98

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

99

Transient and Pseudosteady-State Productivity of Hydraulically Fractured Well  

E-print Network

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

Lumban Gaol, Ardhi

2012-10-19

100

Gas condensate damage in hydraulically fractured wells  

E-print Network

......................................................................8 III PRODUCTION IMPAIRMENT .................................................................10 3.1 Wellbore skin effects ....................................................................11 3.2 Fracture face skin... APPENDIX A GASSIM DATA FILE FOR HAWKINS? APPROACH.....................42 APPENDIX B GASSIM DATA FILE FOR FRACTURE FACE SKIN SIMULATION.....................................................................................43...

Adeyeye, Adedeji Ayoola

2004-09-30

101

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

SciTech Connect

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

Mineyuki Hanano; Tayuki Kondo

1992-01-01

102

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

E-print Network

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

Peirce, Anthony

103

Quantifying Representative Hydraulic Conductivity for Three-Dimensional Fractured Formations  

NASA Astrophysics Data System (ADS)

The fractures and pores in rock formations are the fundamental units for flow and contaminant transport simulations. Due to technical and logical limitations it is difficult in reality to account for such small units to model flow and transport in large-scale problems. The concept of continuum representations of fractured rocks is then used as an alternative to solve for flow and transport in complex fractured formations. For these types of approaches the determinations of the representative parameters such as hydraulic conductivity and dispersion coefficient play important roles in controlling the accuracy of simulation results for large-scale problems. The objective of this study is to develop a discrete fracture network (DFN) model and the associated unstructured mesh generation system to characterize the continuum hydraulic conductivity for fractured rocks on different scales. In this study a coupled three-dimensional model of water flow, thermal transport, solute transport, and geochemical kinetic/equilibrium reactions in saturated/unsaturated porous media (HYDROGEOCHEM) is employed to be the flow simulator to analyze the flow behaviors in fracture formations. The fracture network model and the corresponding continuum model are simulated for same scale problems. Based on the concept of mass conservation in flow, the correlations between statistics of fracture structure and the representative continuum parameters are quantified for a variety of fracture distribution scenarios and scales. The results of this study are expected to provide general insight into the procedures and the associated techniques for analyzing flow in complex large-scale fractured rock systems.

Lee, I.; Ni, C.

2013-12-01

104

Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs  

SciTech Connect

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

Stephen Holditch; A. Daniel Hill; D. Zhu

2007-06-19

105

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

E-print Network

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

Marpaung, Fivman

2008-10-10

106

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

USGS Publications Warehouse

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

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

1988-01-01

107

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

E-print Network

4/6/2014 EU Drafts Hydraulic Fracturing Guidelines to Mitigate Conflicting Laws | The DailyEnergyReport http://www.dailyenergyreport.com/eu-drafts-hydraulic-fracturing Transportation Generation Finance Government Attend Watch EU Drafts Hydraulic Fracturing Guidelines to Mitigate

Chiao, Jung-Chih

108

Fractured: Experts examine the contentious issue of hydraulic fracturing water use  

E-print Network

14 tx H2O Winter 2013 Story by Kathy Wythe FRACTURED Experts examine the contentious issue of hydraulic fracturing water use In a state where oil and gas are king, and water is#29; in words commonly a#20;ributed to Mark Twain#29; ?for #30...;ghting over,? an unconventional method that uses water to extract oil and gas from Texas? underground #30;elds is causing passionate debate. #31;is method#29;hydraulic fracturing#29;uses water and other #14;uids under pressure to fracture or crack...

Wythe, Kathy

2013-01-01

109

Hydraulic tomography offers improved imaging of heterogeneity in fractured rocks.  

PubMed

Fractured rocks have presented formidable challenges for accurately predicting groundwater flow and contaminant transport. This is mainly due to our difficulty in mapping the fracture-rock matrix system, their hydraulic properties and connectivity at resolutions that are meaningful for groundwater modeling. Over the last several decades, considerable effort has gone into creating maps of subsurface heterogeneity in hydraulic conductivity (K) and specific storage (Ss ) of fractured rocks. Developed methods include kriging, stochastic simulation, stochastic inverse modeling, and hydraulic tomography. In this article, I review the evolution of various heterogeneity mapping approaches and contend that hydraulic tomography, a recently developed aquifer characterization technique for unconsolidated deposits, is also a promising approach in yielding robust maps (or tomograms) of K and Ss heterogeneity for fractured rocks. While hydraulic tomography has recently been shown to be a robust technique, the resolution of the K and Ss tomograms mainly depends on the density of pumping and monitoring locations and the quality of data. The resolution will be improved through the development of new devices for higher density monitoring of pressure responses at discrete intervals in boreholes and potentially through the integration of other data from single-hole tests, borehole flowmeter profiling, and tracer tests. Other data from temperature and geophysical surveys as well as geological investigations may improve the accuracy of the maps, but more research is needed. Technological advances will undoubtedly lead to more accurate maps. However, more effort should go into evaluating these maps so that one can gain more confidence in their reliability. PMID:24749939

Illman, Walter A

2014-01-01

110

Experimental determination of hydraulic anisotropy in fractured formations  

SciTech Connect

Discontinuities in a rock mass are defined as the planes of weakness of structural origin and commonly include fractures, faults, and joints. Many numerical solutions have been proposed which are based on stochastic generation of fractures to represent the actual field conditions; however, this approach neglects the role of the actual discontinuities, and results in misleading conclusions. A model was constructed based on fracture trace mapping. Fracture traces are the surficial expressions of the planes of weakness present in the underlying rock mass and can be seen on aerial photographs and Landsat images. Two fractured formations present in the Black Hills region of South Dakota were selected as prototypes. The Madison Formation composed of limestone and dolomite, and the Minnelusa Formation consisting of sandstone and shale with interbeds of limestone and dolomite. Fracture trace patterns served as overlays for the laboratory flow experiments. A two-dimensional flow cell was constructed. To simulate the field conditions, cuts were made of the fracture trace patterns in impervious glazed vinyl sheets. This resulted in smooth walled polygonal shaped pieces which were glued firmly onto the flow cell. The flow was thus restricted within the fracture walls, conforming to the parallel plate analogy. By scaling down the hydrodynamic field conditions, outflow was measured for each run. The plot of the measured data resulted in the best fit ellipse. The major and minor principal axes of this ellipse indicate the maximum and minimum hydraulic conductivities. A close match of the experimental hydraulic conductivity values with that of the field data validated the use of fracture trace analysis for determining the hydraulic anisotropy in fractured formations.

Cheema, T.J.; Islam, M.R. (South Dakota School of Mines and Technology, Rapid City, SD (United States). Dept. of Geology and Geological Engineering)

1994-09-01

111

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

E-print Network

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

Berthelot, Jan Marie

2012-06-07

112

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

113

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

114

Seismic signatures of two orthogonal sets of vertical microcorrugated fractures  

E-print Network

Seismic signatures of two orthogonal sets of vertical microcorrugated fractures Rodrigo Fel, Golden, CO, 80401-1887 (May 25, 2006) ABSTRACT Conventional fracture-characterization techniques operate) of fracture surfaces. Here, we develop analytic solutions based on the linear-slip theory to examine wave

Tsvankin, Ilya

115

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

Federal Register 2010, 2011, 2012, 2013

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

2010-06-25

116

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

E-print Network

Hydraulic fracture conductivity in ultra-low permeability shale reservoirs is directly related to well productivity. The main goal of hydraulic fracturing in shale formations is to create a network of conductive pathways in the rock which increase...

Kamenov, Anton

2013-04-11

117

Investigation of Created Fracture Geometry through Hydraulic Fracture Treatment Analysis  

E-print Network

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

Ahmed, Ibraheem 1987-

2012-11-30

118

Cyclic steaming of tar sands through hydraulically induced fractures  

SciTech Connect

Fracture dimensions and process mechanisms that resulted from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed with numerical modeling. Horizontal fracture radii of 100 ft (30.5 m) and vertical fracture half-lengths of 250 ft (76.2 m) with fracture surface areas of 30,000 to 70,000 sq ft (2787 to 6503 m/sup 2/) are sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation. Mechanisms that are important during fluid loading and unloading of induced fractures include thermal expansion of tar oil, countercurrent imbibition of water and oil caused by capillary pressure effects, and fracture compressibility.

Dietrich, J.K.

1986-05-01

119

Experimental Investigation on the Basic Law of Hydraulic Fracturing After Water Pressure Control Blasting  

NASA Astrophysics Data System (ADS)

Because of the advantages of integrating water pressure blasting and hydraulic fracturing, the use of hydraulic fracturing after water pressure control blasting is a method that is used to fully transform the structure of a coal-rock mass by increasing the number and range of hydraulic cracks. An experiment to study hydraulic fracturing after water pressure blasting on cement mortar samples (300 × 300 × 300 mm3) was conducted using a large-sized true triaxial hydraulic fracturing experimental system. A traditional hydraulic fracturing experiment was also performed for comparison. The experimental results show that water pressure blasting produces many blasting cracks, and follow-up hydraulic fracturing forces blasting cracks to propagate further and to form numerous multidirectional hydraulic cracks. Four macroscopic main hydraulic cracks in total were noted along the borehole axial and radial directions on the sample surfaces. Axial and radial main failure planes induced by macroscopic main hydraulic cracks split the sample into three big parts. Meanwhile, numerous local hydraulic cracks were formed on the main failure planes, in different directions and of different types. Local hydraulic cracks are mainly of three types: local hydraulic crack bands, local branched hydraulic cracks, and axial layered cracks. Because local hydraulic cracks produce multiple local layered failure planes and lamellar ruptures inside the sample, the integrity of the sample decreases greatly. The formation and propagation process of many multidirectional hydraulic cracks is affected by a combination of water pressure blasting, water pressure of fracturing, and the stress field of the surrounding rock. To a certain degree, the stress field of surrounding rock guides the formation and propagation process of the blasting crack and the follow-up hydraulic crack. Following hydraulic fracturing that has been conducted after water pressure blasting, the integrity of the sample is found to be far lower than after traditional hydraulic fracturing; moreover, both the water injection volume and water injection pressure for hydraulic fracturing after water pressure blasting are much higher than they are for traditional hydraulic fracturing.

Huang, Bingxiang; Li, Pengfeng; Ma, Jian; Chen, Shuliang

2014-07-01

120

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

E-print Network

, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation the simulated fracturing network as the objective for maximizing energy recovery sweep efficiency. The surrogate Ltd. All rights reserved. 1. Introduction Hydraulic communication is a key factor for determining

Lu, Zhiming

121

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

122

Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers  

E-print Network

that fracking the shale could reduce that transport time to tens or hundreds of years. Conductive faults to reach a new equilibrium reflecting the significant changes caused by fracking the shale, which could for development. Hydraulic fracturing (fracking, the industry term for the operation; Kramer 2011) loosens

123

GEOL440, GEOL524 Sedimentary Geology: Hydraulic Fracturing Seminar  

E-print Network

-directed seminar class in which we will investigate the issues surrounding hydraulic fracturing (fracking of fracking, Illinois law, and the economic, environmental and political issues involved in this petroleum on the state of the science of fracking. Course Objectives Upon completion of this course, students

Nickrent, Daniel L.

124

Marcellus Shale Drilling and Hydraulic Fracturing; Technicalities and  

E-print Network

;UNITED STATES SHALE BASINS Modern Shale Gas Development in the U.S.: A Primer, (2009) U.S. Dept of EnergyMarcellus Shale Drilling and Hydraulic Fracturing; Technicalities and Controversies Kyle J Ferrar #12;Conventional Gas Plays http://www.dcnr.state.pa.us/topogeo/education/es8.pdf #12;Unconventional

Jiang, Huiqiang

125

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...

126

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

127

Reply to Davies: Hydraulic fracturing remains a possible mechanism for  

E-print Network

LETTER Reply to Davies: Hydraulic fracturing remains a possible mechanism for observed methane frac- turing (2). We respond briefly, noting that we carefully avoided ascribing any mechanism the mechanism of contamination better. Comments about sampling procedures and methane seeps are in refs. 3 and 4

Jackson, Robert B.

128

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

129

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

130

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

131

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

132

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

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

2014-07-01

133

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

Federal Register 2010, 2011, 2012, 2013

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

2012-06-26

134

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

E-print Network

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

Peirce, Anthony

135

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

E-print Network

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

Boyer, Edmond

136

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

Federal Register 2010, 2011, 2012, 2013

...research on the potential impacts of hydraulic...fracturing on drinking water resources. DATES...to understand the potential impacts of hydraulic...fracturing on drinking water resources, if any...research study on the potential impacts of hydraulic...fracturing on drinking water resources....

2012-11-09

137

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

Federal Register 2010, 2011, 2012, 2013

...research on the potential impacts of hydraulic...fracturing on drinking water resources from April...entitled, Study of the Potential Impacts of Hydraulic...Fracturing on Drinking Water Resources: PROGRESS...literature specific to potential impacts of hydraulic...fracturing on drinking water resources....

2013-04-30

138

Computer Simulation of Hydraulic Fracturing in Shales-Influences on Primary Migration  

Microsoft Academic Search

Hydraulic tension fractures in a shale layer during sedimentation are simulated by use of computer techniques. The depth at which fractures form is directly proportional to the hydraulic conductivity and tensile strength, and inversely proportional to the rate of sedimentation and thickness of the shale layer. Hydraulic fractures may form at depths of oil generation to facilitate primary migration. This

Ismail Ozkaya

1984-01-01

139

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

E-print Network

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

140

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

E-print Network

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

Peirce, Anthony

141

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

E-print Network

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

Mohaghegh, Shahab

142

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

E-print Network

Click Here for Full Article A model for turbulent hydraulic fracture and application to crack suggest that fluidinduced hydraulic fracture of an ice sheet from its bed sometimes occurs quickly. Citation: Tsai, V. C., and J. R. Rice (2010), A model for turbulent hydraulic fracture and application

143

Injection-Sensitive Mechanics of Hydraulic Fracture Interaction with Discontinuities  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

144

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

145

Combined seismic and hydraulic method of modeling flow in fractured low permeability rocks  

SciTech Connect

Modeling flow of ground water in hard rocks where a network of fractures provides the dominant flow paths is a major problem. This paper summarizes a program of investigations currently underway in this laboratory to characterize the geometry of fractured rocks and develop methods of handling flow in such systems. Numerical models have been developed to investigate flow behavior in two- and three-dimensional fracture networks. The results demonstrate the insights that can be gained from modeling studies of fractured rocks. A key problem is gathering the necessary data on fracture geometry. Investigations have been started to determine how vertical seismic profiling (VSP) might be improved and applied to this problem. A VSP experiment in The Geysers geothermal field in northern California, where fracture orientation is known, produced shear wave splitting and velocity anisotropy in agreement with theory. The results suggest the potential application of 3-component, multi-source VSP data in determining fracture orientation and average spacing. We believe a combination of seismic and hydraulic methods can greatly enhance an understanding of fluid flow and transport in low permeability rock systems where fractures provide the dominant paths. 40 refs, 16 figs., 4 tabs.

Witherspoon, P.A.; Long, J.C.S.; Majer, E.L.; Myer, L.R.

1987-06-01

146

Effects of non-Darcy flow on pressure buildup analysis of hydraulically fractured gas reservoirs  

E-print Network

Conventional well-testing techniques are commonly used to evaluate pressure transient tests of hydraulically fractured wells to estimate values such as formation permeability, fracture length, and fracture conductivity. When non-Darcy flow occurs...

Alvarez Vera, Cesar

2012-06-07

147

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

E-print Network

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

Li, Yingping

1996-01-01

148

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

E-print Network

Interference Fracturing: Non-Uniform Distributions of Perforation Clusters that Promote Simultaneous Growth of Multiple Hydraulic Fractures A.P. Peirce, University of British Columbia and A.P. Bunger in horizontal well stimulation is the generation of hydraulic fractures (HFs) from all perforation clusters

Peirce, Anthony

149

Characterizing hydraulic properties of filter material of a Vertical Flow1 Constructed Wetland2  

E-print Network

Characterizing hydraulic properties of filter material of a Vertical Flow1 Constructed Wetland2 A Characterizing the hydraulic properties of filter material used in a vertical flow11 constructed wetland (VFCW of porous mineral material and13 organic matter that makes hydraulic characterization a difficult task. Here

Paris-Sud XI, Université de

150

Detection of Open Fractures with Vertical Seismic Profiling  

E-print Network

In Vertical Seismic Profiling surveys tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The problem of generation of these waves by a non-normal incident P wave for an ...

Beydoun, W. B.

1984-01-01

151

Mechanical stability of propped hydraulic fractures: A numerical study  

SciTech Connect

Proppant is sometimes produced along with hydrocarbons in hydraulically fractured petroleum wells. Sometimes 10% to 20% of the proppant is backproduced, which can lead to damaged equipment and downtime. Furthermore, proppant flowback can lead to a substantial loss of fracture conductivity. A numerical study was conducted to help understand what conditions are likely to lead to proppant flowback. In the simulations, the mechanical interaction of a larger number (several thousand) individual proppant grains was modeled with a distinct-element-type code. The numerical simulations show that hydraulic fractures propped with cohesionless, unbonded proppant fail under closure stress at a critical ratio of mean grain diameter to fracture width. This is consistent with published laboratory studies. The simulations identify the mechanism (arch failure) that triggers the mechanical instability and also show that the primary way that drawdowns (less than {approx} 75 psi/ft) affect proppant flowback is to transport loose proppant grains in front of the stable arch to the wellbore. Drawdowns > 75 psi/ft are sufficient to destabilize the arch and to cause progressive failure of the propped fractures.

Asgian, M.I.; Cundall, P.A. [Itasca Consulting Group Inc., Minneapolis, MN (United States); Brady, B.H. [Schlumberger Dowell, Tulsa, OK (United States). Applied Mechanics and Engineering Dept.

1995-03-01

152

On modeling hydraulic fracture in proper variables: stiffness, accuracy, sensitivity  

E-print Network

The problem of hydraulic fracture propagation is considered by using its recently suggested modified formulation in terms of the particle velocity, the opening in the proper degree, appropriate spatial coordinates and $\\varepsilon$-regularization. We show that the formulation may serve for significant increasing the efficiency of numerical tracing the fracture propagation. Its advantages are illustrated by re-visiting the Nordgren problem. It is shown that the modified formulation facilitates (i) possibility to have various stiffness of differential equations resulting after spatial discretization, (ii) obtaining highly accurate and stable numerical results with moderate computational effort, and (iii) sensitivity analysis. The exposition is extensively illustrated by numerical examples.

Mishuris, Gennady; Linkov, Alexander

2012-01-01

153

Performance of petroleum reservoirs containing random vertical fractures  

E-print Network

PERFORMANCE OF PETROLEUM RESERVOIRS CONTAINING RANDOM VERTICAL FRACTURES A Thesis By WILLIAM LYMAN HUSKEY Approved as to style and content by: Chairxnan o Coxnxnittee ead of Departxnent PERFORMANCE OF PETROLEUM RESERVOIRS CONTAINING RANDOM... VERTICAL FRACTURES A Thesis By WILLIAM LYMAN HUSKEY Submitted to the Graduate School of the Agricultural and Mechanical College of Te~s in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August, f 963 Major Subject...

Huskey, William Lyman

2012-06-07

154

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

SciTech Connect

The Yowlumne field is a giant field in the southern San Joaquin basin, Kern County, California. It is a deep (13,000 ft) waterflood operation that produces from the Miocene- aged Stevens Sand. The reservoir is interpreted as a layered, fan-shaped, prograding turbidite complex containing several lobe-shaped sand bodies that represent distinct flow units. A high ultimate recovery factor is expected, yet significant quantities of undrained oil remain at the fan margins. The fan margins are not economic to develop using vertical wells because of thinning pay, deteriorating rock quality, and depth. This project attempts to demonstrate the effectiveness of exploiting the northeast distal fan margin through the use of a high- angle well completed with multiple hydraulic- fracture treatments. A high-angle well offers greater pay exposure than can be achieved with a vertical well. Hydraulic-fracture treatments will establish vertical communication between thin interbedded layers and the wellbore. The equivalent production rate and reserves of three vertical wells are anticipated at a cost of approximately two vertical wells. The near-horizontal well penetrated the Yowlumne sand; a Stevens sand equivalent, in the distal fan margin in the northeast area of the field. The well was drilled in a predominately westerly direction towards the interior of the field, in the direction of improving rock quality. Drilling and completion operations proved to be very challenging, leading to a number of adjustments to original plans. Hole conditions resulted in obtaining less core material than desired and setting intermediate casing 1200 ft too high. The 7 in. production liner stuck 1000 ft off bottom, requiring a 5 in. liner to be run the rest of the way. The cement job on the 5 in. liner resulted in a very poor bond, which precluded one of three hydraulic fracture treatments originally planned for the well. Openhole logs confirmed most expectations going into the project about basic rock properties: the formation was shaly with low porosities, and water saturations were in line with expectations, including the presence of some intervals swept out by the waterflood. High water saturations at the bottom of the well eliminated one of the originally planned hydraulic fracture treatments. Although porosities proved to be low, they were more uniform across the formation than expected. Permeabilities of the various intervals continue to be evaluated, but appear to be better than expected from the porosity log model derived in Budget Period One. The well was perforated in all pay sections behind the 5 in. liner. Production rates and phases agree nicely with log calculations, fractional flow calculations, and an analytical technique used to predict the rate performance of the well.

Laue, M.L.

1997-11-21

155

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

156

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

157

Effects of skin and hydraulic fractures on SVE wells.  

PubMed

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

Bradner, Graham C; Murdoch, Lawrence C

2005-05-01

158

Methodologies and new user interfaces to optimize hydraulic fracturing design and evaluate fracturing performance for gas wells  

E-print Network

This thesis presents and develops efficient and effective methodologies for optimal hydraulic fracture design and fracture performance evaluation. These methods incorporate algorithms that simultaneously optimize all of the treatment parameters...

Wang, Wenxin

2006-04-12

159

Interpretation of resonance frequencies recorded during hydraulic fracturing treatments  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing treatments are often monitored by strings of geophones deployed in boreholes. Instead of picking discrete events only, we here use time-frequency representations of continuous recordings to identify resonances in two case studies. This paper outlines an interpretational procedure to identify their cause using a subdivision into source, path, and receiver-side effects. For the first case study, two main resonances are observed both at depth by the downhole geophones and on the surface by two broadband arrays. The two acquisition networks have different receiver and path effects, yet recorded the same resonances; these resonances are therefore likely generated by source effects. The amplitude pattern at the surface arrays indicates that these resonances are probably due to pumping operations. In the second case study, selective resonances are detected by the downhole geophones. Resonances coming from receiver effects are either lower or higher frequency, and wave propagation modeling shows that path effects are not significant. We identify two possible causes within the source area, namely, eigenvibrations of fractures or non-Darcian flow within the hydraulic fractures. In the first situation, 15-30 m long fluid-filled cracks could generate the observed resonances. An interconnected fracture network would then be required, corresponding to mesoscale deformation of the reservoir. Alternatively, systematic patterns in non-Darcian fluid flow within the hydraulic fracture could also be their leading cause. Resonances can be used to gain a better understanding of reservoir deformations or dynamic fluid flow perturbations during fluid injection into hydrocarbon and geothermal reservoirs, CO2 sequestration, or volcanic eruptions.

Tary, J. B.; Baan, M.; Eaton, D. W.

2014-02-01

160

Model of stepwise propagation of the tip of a hydraulic fracture in the absence of filtration  

NASA Astrophysics Data System (ADS)

Quasi-static stepwise propagation of a hydraulic fracture in rock with a regular structure in the absence of filtration is considered. It is proposed to use a brittle fracture diagram taking into account the hydraulic fracturing fluid pressure and the confining pressure. Fracture curves describing the brittle rock fracture where the hydraulic fracturing fluid partially fills the fracture are constructed and used to predicted the possibility of stepwise propagation of hydraulic fracturing in the case where the fluid gradually flows into the fracturing crack. The regularity of the structure of the brittle rocks fracture is estimated from the results of two full-scale experiments: the critical stress intensity factor and the tensile strength limit of the rock. Experiments on pulsed loading of polymethylmethacrylate samples with stepwise crack propagation along concentric circular arcs were performed. The results of the experiments are consistent with theoretical predictions.

Kornev, V. M.; Demeshkin, A. G.

2014-05-01

161

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

E-print Network

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

Peirce, Anthony

162

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

E-print Network

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

Santos, Juan

163

Borehole deviation surveys are necessary for hydraulic fracture monitoring Leo Eisner, Schlumberger Cambridge Research, Petr Bulant, Charles University in Prague, Jol H. Le Calvez*,  

E-print Network

Borehole deviation surveys are necessary for hydraulic fracture monitoring Leo Eisner, Schlumberger Not performing accurate borehole deviation surveys for hydraulic fracture monitoring (HFM) and neglecting fracture parameters. Introduction Recently a large number of hydraulic fracture treatments have been

Cerveny, Vlastislav

164

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

165

Hydraulic fracture characterization resulting from low-viscosity fluid injection: Implications for CO2 sequestration  

NASA Astrophysics Data System (ADS)

The initiation of hydraulic fractures during CO2 sequestration can be either engineered or induced unintentionally. Some fractures may be desirable such as horizontal fractures that can facilitate fluid injection and migration; whereas some fractures may be unfavorable if the fractures tend to extend vertically above a certain limit, thus creating a potential leaking condition. Historically, carbon dioxide as a liquefied gas has been used in oil and gas field stimulation since the early1960s because it eliminates formation damage and residual fluids. Carbon dioxide injection is considered to be one of the most effective technologies for improving oil recovery from hard-to-extract oil reserves because CO2 is effective in penetrating the formation due to its high diffusivity, while the rock associated with petroleum-containing formations is generally porous. However, low viscosity and high compressibility fluids such as CO2 exhibit different effects on the hydraulic fracture initiation/propagation behavior in comparison with high viscosity and low compressibility fluids. Laboratory tests show that viscous fluids tend to generate thick and planar cracks with few branches, while low viscosity fluids tend to generate narrow and wavelike cracks with many secondary branches. A numerical comparison between water and supercritical CO2-like fluid has been made to investigate the influence of fluids to fracture propagation behavior. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Thin fluids with properties of supercritical CO2 will create relatively thin and much shorter fractures in comparison to fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation. One is the time at which a crack ceases opening, and he other is the time at which a crack ceases propagating, with the former always occurring before the latter. These times are very different for different fluids. Both fluid compressibility and viscosity are important in the behavior of fracture propagation with viscosity being the most important property. Viscosity can greatly affect the magnitude of hydraulic conductivity and the value of the leak-off coefficient. This study has important implications for CO2 sequestration.

Burbey, T. J.; Zhou, X.

2013-12-01

166

Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, July 1--September 30, 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 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 has been drilled. After pumping a remedial cement squeeze, all pay behind the 5 in. liner was perforated and stimulated. Once wellwork is complete for the existing perforations, a hydraulic fracture treatment will be pumped through a short interval of clustered perforations in the 7 in. liner. Following this frac, all pay behind the 7 in. liner will be perforated and completion operations will be final.

Laue, M.L.

1997-10-30

167

Microseismic Evidence for the Interaction of Faulting and Fluid Flow During Hydraulic Fracture Injection  

NASA Astrophysics Data System (ADS)

Microearthquake induced during hydraulic fracture treatments were precisely located using data from two borehole arrays of 3-component geophones. The treatments were conducted within interbedded sands and shales of the Upper Cotton Valley formation, located in east Texas. The microearthquakes occurred within narrow horizontal bands that correspond to sandstone layers that were specifically targeted for gas production. Double couple (DC), composite focal mechanism inversions indicate strike-slip faulting occurring uniformly along vertical fractures trending close to maximum horizontal stress direction. The banding of events and the slip-plane orientations are close to the reservoir's prevalent natural fractures, known to be isolated within the sands and trending subparallel to the expected hydraulic fracture orientation. Full moment tensor solutions were also attempted by amplitude inversion using higher signal-to-noise events. Significant non-DC components are possible including tensional crack components, but are often poorly resolved due to limited focal sphere coverage. Assuming Coulomb failure criteria, the observation of horizontal slip along fractures subparallel to maximum-horizontal stress implies a relatively high critical pore pressure. Thus, it is reasonable to expect fracture opening is accompanying slip and that the seismicity is directly associated with the activated fluid-flow paths. Faulting, in turn, appears to affect the fluid flow, as evident from the time-space patterns of seismicity. Anomalous event counts and moment release sometimes occur within dense clusters that delineate bends or jogs in the fracture zones. The dense clusters show location patterns diverging in time, suggesting the expulsion of fluid from compressive fault jogs. These jogs likely form choke points where the slip-induced loading tends to lock up and concentrate stress at the jogs, as evident by fewer but larger events populating the structures as injection proceeds.

Rutledge, J.; Sileny, J.; Vavrycuk, V.; Jechumtalova, Z.; Eisner, L.

2006-12-01

168

Effect of shear displacement on the hydraulic conductivity of a fracture  

Microsoft Academic Search

The effect of shear displacement inclined relative to macroscopic water flow on the hydraulic conductivity of a rock fracture was estimated, using synthetic fractures that reproduce a tensile fracture in granite. The results showed that the hydraulic aperture normalized by the mean aperture increased with the angle between the directions of shear displacement and macroscopic water flow, according to a

K. Matsuki; Y. Kimura; K. Sakaguchi; A. Kizaki; A. A. Giwelli

2010-01-01

169

Page 1 of 5 Narrative Description of Hydraulic Fracturing Draft Regulations  

E-print Network

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

170

Asymptotic Analysis of Cross-Hole Hydraulic Tests in Fractured Granite  

E-print Network

Asymptotic Analysis of Cross-Hole Hydraulic Tests in Fractured Granite by Walter A. Illman1 hydraulic conductivity and specific storage. Introduction Well test analyses in porous and fractured for the interpretation of three-dimensional pneumatic well tests conducted in porous or fractured geologic media, which

Daniels, Jeffrey J.

171

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

Microsoft Academic Search

It has been suggested that a substantial amount of heat energy could be extracted from dry hot rocks near the earth's surface by circulating a fluid through large hydraulic fractures. However a theoretical analysis of propagation and closure of hydraulic fractures subject to realistic stress gradients indicates an upper limit for the size of a stable fracture. For example, if

Donald T. Secor; David D. Pollard

1975-01-01

172

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

E-print Network

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

Marpaung, Fivman

2009-05-15

173

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

174

Field investigation of heat transfer in hydraulic fractures and the effect of heat transfer on fracturing fluid design  

SciTech Connect

Fracturing fluid temperature is a key variable in the design of hydraulic fracturing treatments and the formulation of fracturing fluids. Heat transfer in a hydraulic fracture dictates the fluid formulation and the concentration of chemical {open_quotes}breakers{close_quotes} used to degrade the fluid and maximize proppant pack conductivity. This paper contains the results of an investigation of heat transfer in hydraulic fractures, and documents the recording of bottomhole temperature during Piceance Basin Mesaverde fracturing treatments and during immediate flow back ({open_quotes}forced closure{close_quotes}). Bottomhole temperature was measured with a gauge set in a perforated interval, and the data shows minimal {open_quotes}cool down{close_quotes} of fracturing fluids, i.e., flow back temperatures increased rapidly to near bottomhole static temperature. Computer simulations are also presented and a fracturing fluid design methodology is suggested which balances fluid rheological requirements with degradation requirements, for maximizing proppant pack conductivity.

Craig, D.P.; Brown, T.D.; Ely, J.W.

1996-12-31

175

A decision-analytic approach to predict state regulation of hydraulic fracturing  

E-print Network

Background: The development of horizontal drilling and hydraulic fracturing methods has dramatically increased the potential for the extraction of previously unrecoverable natural gas. Nonetheless, the potential risks and ...

Linkov, Igor

176

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

E-print Network

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

Amini, Kaveh

2014-01-01

177

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils  

E-print Network

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

Mohanty, Binayak P.

178

Hydraulic fracturing in faulted sedimentary basins: Numerical simulation of potential contamination of shallow aquifers over long  

E-print Network

fracturing (hydrofracturing or ``fracking'') is generally used [BAPE, 2011; EPA, 2012]. Hydraulic fracturing, which returns to the surface [Gregory et al., 2001]. The fracking fluid is commonly composed of $99

McKenzie, Jeffrey M.

179

The Implications and Flow Behavior of the Hydraulically Fractured Wells in Shale Gas Formation  

E-print Network

approaches is by drilling horizontal wells and hydraulically fracturing the formation. Once the formation is fractured, different flow patterns will occur. The dominant flow regime observed in the shale gas formation is the linear flow or the transient...

Almarzooq, Anas Mohammadali S.

2012-02-14

180

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

E-print Network

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

Pongthunya, Potcharaporn

2009-06-02

181

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...

182

Hydraulic Fracturing, Wastewater Injection and Unintended Earthquakes (Invited)  

NASA Astrophysics Data System (ADS)

It has long been known that increasing the pore pressure within a pre-stressed fault can induce an earthquake by reducing the effective normal stress and thereby the frictional strength of the fault. Underground fluid pressures are routinely modified by a wide range of industrial activities including impoundment of reservoirs, mining, and petroleum production, all of which are known to have potential for inducing earthquakes. Recently, attention has been drawn to the earthquake hazard associated with the production of oil and gas from previously unproductive formations. Earthquakes can be induced as part of the process to stimulate the production from tight shale formations, or by disposal of wastewater associated with stimulation and production. In this talk, I review recent investigations of both activities with a focus on the emerging understanding of the development of predictive models for both seismicity and risk. By design, hydraulic fracturing induces numerous high-frequency microseismic events as part of the process of creating a connected fracture network to enhance formation permeability. During the brief time (hours) that high fluid pressure is applied to the well bore, seismic events occur as a combination tensile (hydrofracture) and shear (hydroshear) failures. The fluid volume injected in a single hydrofrac stage is commonly of the order of several thousand cubic meters. Growth of the fracture network typically follows square-root scaling with time, suggesting a diffusive growth mechanism. Magnitudes are normally below zero for events in the target formation. Larger, unintended events sometimes occur and available evidence points to shear failure of pre-existing faults as their source. Earthquakes with magnitudes as large as Mw 3.6 occurred during hydraulic fracturing operations in the Horn River Basin, B. C., Canada. Some of these occurred before the diffusive pressure front would have reached the hypocenter, suggesting rapid transmission of pore pressure through conductive fractures or faults. In contrast with hydraulic fracturing treatments, wastewater wells commonly inject fluid for years or decades, with cumulative volumes occasionally in excess of 1 million cubic meters. By design, wastewater injection should never induce hydraulic fractures, as regulations require injection pressures to be less than the fracture pressure. Avoiding earthquakes has proven to be more problematic, at least for a small percentage of the more than 30,000 UIC Class II wells in the U.S. that are licensed for wastewater disposal. Case studies of some of the larger of the recent earthquakes induced by wastewater injection suggest triggering by transmission of the pore pressure increase to well-oriented faults in the basement. Ultimately, better knowledge of the stress and pressure conditions at depth; the hydrogeologic framework, including the presence and geometry of faults; and the location and mechanisms of natural seismicity at a few sites will be needed to develop a predictive understanding of the hazard posed by induced earthquakes.

Ellsworth, W. L.

2013-12-01

183

A Network Modeling Approach to Derive Unsaturated Hydraulic Properties of a Rough-Walled Fracture  

Microsoft Academic Search

The hydraulic properties of a rough-walled fracture in a limestone sample are estimated using a network model based on three-dimensional representations of the fracture apertures. Two different scenarios are considered: drainage of water out of a fracture and infiltration of water into a fracture. Besides capillary effects, the model takes into account an accessibility criterion (invasion percolation) and, in the

Katrijn Vandersteen; Jan Carmeliet; Jan Feyen

2003-01-01

184

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

185

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

186

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...published in the Federal Register a proposed rule to regulate hydraulic fracturing on Federal and Indian land. Due to the...

2013-06-10

187

Oil and Gas CDT Quantification of hydraulic fracturing induced seismic risks  

E-print Network

quantification Overview Hydraulic fracturing or "fracking" is a technique that uses fluids, pumped at high. Seismic risks due to hydraulic fracturing have been identified following the fracking activities predictions of the coupled multi-physics phenomenon of fracking might arise from two primary sources

Henderson, Gideon

188

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

Microsoft Academic Search

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

I. Berchenko; E. Detournay

1997-01-01

189

DETECTION WITHIN THE WELLBORE OF SEISMIC SIGNALS CREATED BY HYDRAULIC FRACTURING  

Microsoft Academic Search

Early in 1978, Sandia Labs participated in massive hydraulic fracture mapping experiments with Amoco in the Wattenburg area. On two of these massive hydraulic fractures in the Sussex formation, a downhole, wall clamped, three-axis geophone was tested. On the first experiment, the system was clamped in the open hole section during the breakdown phase. On the second experiment, the system

Carl Schuster

1978-01-01

190

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

E-print Network

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

Zhan, Hongbin

191

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

E-print Network

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

Paris-Sud XI, Université de

192

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...

193

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

EPA Science Inventory

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

194

Solution of hydraulic fracture problem accounting for lag  

E-print Network

The paper presents a method for solving hydraulic fracture problems accounting for the lag. The method consists in matching the outer (basic) solution neglecting the lag, with the inner (auxiliary) solution of the derived 1D integral equation with conditions, accounting for the lag and asymptotic behavior of the opening and the net-pressure. The method refers to practically important cases, when the influence of the local perturbation, caused by the lag, becomes insignificant at a distance, where the leading plane-state asymptotics near the fracture front is still applicable. The universal asymptotics are used for finding the matching constants of the basic (outer) solution and for formulation of matching condition for the solution of inner (auxiliary) problem. The method is illustrated by the solution of the Spence and Sharp plane-strain problem for a fracture propagating symmetrically from the inlet, where a Newtonian fluid is pumped at a constant rate. It is stated that the method developed for deep fractu...

Linkov, Alexander M

2014-01-01

195

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

USGS Publications Warehouse

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

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

2000-01-01

196

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...

197

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

E-print Network

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

Paris-Sud XI, Université de

198

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

199

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

Federal Register 2010, 2011, 2012, 2013

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

2012-06-18

200

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

E-print Network

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

Foulger, G. R.

201

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

E-print Network

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

Peirce, Anthony

202

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

E-print Network

Analysis of Best Hydraulic Fracturing Practices in the Golden Trend Fields of Oklahoma Shahab D of optimized hydraulic fracturing procedure. Detail stimulation data from more than 230 wells in the Golden of hydraulic fractures. Therefore, it is highly recommended that the clastic and carbonate formations

Mohaghegh, Shahab

203

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

E-print Network

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

Paris-Sud XI, Université de

204

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

E-print Network

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

Peirce, Anthony

205

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

E-print Network

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

206

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

E-print Network

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

Vallée, Martin

207

August 22, 2012 (v. 5) Summary of Studies Related to Hydraulic Fracturing Conducted by USGS Water Science Centers  

E-print Network

August 22, 2012 (v. 5) Summary of Studies Related to Hydraulic Fracturing Conducted by USGS Water and hydraulic fracturing on groundwater and surface-water quantity and quality and ecosystems. "On ­ Maps related to oil and gas production and hydraulic fracturing are included in the USGS Fact Sheet

208

Determination of Hydraulically Activated Fractures and Field Stress Tensors in the Barnett Shale Using Microseismic Events Data  

NASA Astrophysics Data System (ADS)

Seismic moment and stress tensor inversions are applied to microseismic events data to investigate the mechanical behavior of activated fractures during hydraulic fracturing in tight reservoirs. The goal is to understand the likelihood of different mechanisms for induced microseismicity, including low pressure fluid leak-off or stress shadowing adjacent to bi-wing parent hydraulic fractures, and pressurized network flow with no parent fracture. The data includes 7,444 microseismic events generated from 18 sequential pumping stages in two adjacent horizontal wells in the Barnett Shale, recorded from two down-hole monitor wells. A tensile source model is used to derive parameters such as nodal plane orientations and slip vectors from the six component moment tensor for each microseismic event. Three-dimensional stress analysis techniques and a linearized stress inversion scheme are used to calculate geomechanical parameters. Four scenarios are considered. The first case considers fractures seismically activated in the in-situ stress field, which is determined from wellbore break-out data in the vertical wells. Fracture activation is assumed to occur by minor stress perturbations with no stress rotation. The second case also considers that the most unstable fractures in the wellbore state of stress activated, but to determine the induced stress state, stress inversion on only the unstable fractures is used. The third case assumes that all of the nodal planes are mechanically valid but that the plane with the lowest misfit, the angle between the observed and predicted slip vector, is the correct one. In this case, the wellbore stress state is ignored entirely and stress inversion on all of the nodal planes is used to solve for the activation stress. The fourth case expands case three by selecting the correct fault plane as the one with the highest instability in the inversion stress state and a second inversion is used on only the unstable fractures. Preliminary results indicate the nodal planes for all events define two fracture sets, which are consistent with natural fracture orientations from image logs and cores in the Barnett. The first set at 044°/70° has the highest instability in the wellbore stress state (case 1: ?1=Sv = vertical; ?2=SHmax=042°). The second set at 125°/68° is most unstable in the stress states calculated from the stress inversions (case 2: ?1=Sv ? vertical; ?2=SHmax=154°; case 3: ?1=Sv ? vertical; ?2=SHmax=130°; case 4: ?1=Sv = vertical; ?2=SHmax=134°). Cases 2-4 show insignificant change in ?1, around 10 MPa reduction in ?2, and significant reduction in ?3 to around 1-4 MPa in tension. The latter suggests conditions of high fluid pressure in a hydraulically connected fracture network, and is consistent with observations that (a) about half of all events show a positive tensile source parameter ?, indicating a dilatant shear mechanism, and (b) in the wellbore stress regime the most critically stressed nodal planes require greater than 2-5 MPa excess fracture/pore fluid pressure to fail in shear. While instability predictions eliminate case 1 as a likely mechanism for activation, to discern cases 2-4, additional work to compare instability, misfit angles, frictional properties, and models for hydraulic fracture development is required.

Busetti, S.

2012-12-01

209

Seismic characterization of vertical fractures described as general linear-slip interfaces  

E-print Network

Seismic characterization of vertical fractures described as general linear-slip interfaces Vladimir fractures which make the medium anisotropic on the scale of seismic wavelength. Applying the linear- slip" vertical fractures embedded in a purely isotropic host rock. The generality of our fracture model means

Tsvankin, Ilya

210

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

211

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

212

Irreducible, incarcerated vertical dislocation of patella into a Hoffa fracture.  

PubMed

Rotational dislocations of patella, which involve rotation of the patella around a horizontal or vertical axis are rare. These rotational dislocations of patella are difficult to reduce by close methods. These dislocations can have associated osteochondral and retinacular injury. We report a case of a 20-year-old male who presented with swelling and pain in the right knee following a motor cycle accident. Radiological evaluation using the computed tomography revealed a patellar dislocation with a concomitant Hoffa fracture. Patella was rotated around the vertical axis and was incarcerated into the Hoffa fracture. This is a very rare injury and first of its kind to be reported. The difficulties in diagnosis, mechanism of injury and management have been discussed. We feel closed reduction of such an injury is likely to fail and open reduction is recommended. PMID:25298564

Soraganvi, Prasad C; Narayan Gowda, Bs; Rajagopalakrishnan, Ramakanth; Gavaskar, Ashok S

2014-09-01

213

EVALUATION OF METHOD FOR DETERMINING THE VERTICAL DISTRIBUTION OF HYDRAULIC CONDUCTIVITY  

EPA Science Inventory

Six borehole methods for determining the vertical distribution of hydraulic conductivity in unconsolidated geologic formations are evaluated. taddle packer tests are inappropriate of there is a hydraulic path around the packer on the outside of the well screen. Methods based on g...

214

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

E-print Network

fractures: Inference1 of fracture geometry from resonant frequencies and2 attenuation3 Bradley P. Lipovsky 1:53am D R A F T #12;X - 2 LIPOVSKY AND DUNHAM: RESONANCE OF HYDRAULIC FRACTURES Abstract. Oscillatory seismic signals arising from resonant vibrations of4 hydraulic fractures are observed in many geologic

Dunham, Eric M.

215

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

216

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

217

Fracture analysis in the south-western Corinth rift (Greece) and implications on fault hydraulic behavior  

NASA Astrophysics Data System (ADS)

This paper reviews the data concerning the fracture network and the hydraulic characteristics of faults in an active zone of the Gulf of Corinth. Pressure gap measured through fault planes shows that in this area the active normal faults (Aigion, Helike) act, at least temporarily and locally, as transversal seal. The analysis of the carbonate cements in the fractures on both the hangingwall and the footwall of the faults also suggests that they have acted as local seals during the whole fault zone evolution. However, the pressure and the characteristics of the water samples measured in the wells indicate that meteoric water circulates from the highest part of the relief to the coast, which means it goes through the fault zones. Field quantitative analysis and core studies from the AIG-10 well have been performed to define both regional and fault-related fracture networks. Then laboratory thin section observations have been done to recognize the different fault rocks characterizing the fault zone components. These two kinds of approach give information on the permeability characteristics of the fault zone. To synthesize the data, a schematic conceptual 3D fluid flow modeling has been performed taking into account fault zone permeability architecture, sedimentation, fluid flow, fault vertical offset and meteoric water influx, as well as compaction water flow. This modeling allows us to fit all the data with a model where the fault segments act as a seal whereas the relays between these segments allow for the regional flow from the Peloponnese topographic highs to the coast.

Micarelli, Luca; Moretti, Isabelle; Jaubert, Manon; Moulouel, Hakim

2006-10-01

218

Preliminary stress measurements in central California using the hydraulic fracturing technique  

USGS Publications Warehouse

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

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

1977-01-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

220

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

NASA Astrophysics Data System (ADS)

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

Jo, Y.; Chang, C.

2013-12-01

221

Real-time and post-frac' 3-D analysis of hydraulic fracture treatments in geothermal reservoirs  

SciTech Connect

Economic power production from Hot Dry Rock (HDR) requires the establishment of an efficient circulation system between wellbores in reservoir rock with extremely low matrix permeability. Hydraulic fracturing is employed to establish the necessary circulation system. Hydraulic fracturing has also been performed to increase production from hydrothermal reservoirs by enhancing the communication with the reservoir's natural fracture system. Optimal implementation of these hydraulic fracturing applications, as with any engineering application, requires the use of credible physical models and the reconciliation of the physical models with treatment data gathered in the field. Analysis of the collected data has shown that 2-D models and 'conventional' 3-D models of the hydraulic fracturing process apply very poorly to hydraulic fracturing in geothermal reservoirs. Engineering decisions based on these more 'conventional' fracture modeling techniques lead to serious errors in predicting the performance of hydraulic fracture treatments. These errors can lead to inappropriate fracture treatment design as well as grave errors in well placement for hydrothermal reservoirs or HDR reservoirs. This paper outlines the reasons why conventional modeling approaches fall short, and what types of physical models are needed to credibly estimate created hydraulic fracture geometry. The methodology of analyzing actual measured fracture treatment data and matching the observed net fracturing pressure (in realtime as well as after the treatment) is demonstrated at two separate field sites. Results from an extensive Acoustic Emission (AE) fracture diagnostic survey are also presented for the first case study aS an independent measure of the actual created hydraulic fracture geometry.

Wright, C.A.; Tanigawa, J.J.; Hyodo, Masami; Takasugi, Shinji

1994-01-20

222

Analysis and numerical modeling of hydraulic fracturing during cyclic steam stimulation in oil sands  

SciTech Connect

Cyclic steam stimulation in oil sands above fracturing pressure is analyzed by numerical modeling. A numerical model is formulated that simultaneously describes the fracturing process and reservoir behavior for different types of fracture geometry. The model is used to study the differences in performance expected for different fracture types. The comparison of model results with the data from a first-cycle cyclic steam operation shows good agreement for single vertical fracture configuration. 21 refs.

Settari, A.; Raisbeck, J.M.

1981-11-01

223

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

E-print Network

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

Fletcher, Sarah Marie

2012-01-01

224

77 FR 27691 - Oil and Gas; Well Stimulation, Including Hydraulic Fracturing, on Federal and Indian Lands  

Federal Register 2010, 2011, 2012, 2013

...if they choose to use pits to store hydraulic fracturing fluids...demulsifier, friction reducer, gel, iron control, oxygen scavenger...more than a 10 percent pressure loss. (e)(1) Monitoring and...demulsifier, friction reducer, gel, iron control, oxygen...

2012-05-11

225

Stochastic Programming Approach to Hydraulic Fracture Design for the Lower Tertiary Gulf of Mexico  

E-print Network

In this work, we present methodologies for optimization of hydraulic fracturing design under uncertainty specifically with reference to the thick and anisotropic reservoirs in the Lower Tertiary Gulf of Mexico. In this analysis we apply a stochastic...

Podhoretz, Seth

2013-07-27

226

Integrated Hydraulic Fracture Placement and Design Optimization in Unconventional Gas Reservoirs  

E-print Network

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

Ma, Xiaodan

2013-12-10

227

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

E-print Network

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

Boyer, Edmond

228

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

229

Texas review of hydraulic fracturing water use and consumption  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing (HF) has a long history in the state of Texas where are located (1) several established plays, such as the Barnett Shale, (2) plays of recent interest, such as the Eagle Ford or the Wolfcamp, and (3) older plays being revisited such as the Wolfberry or the Granite Wash. We compiled current water use for year 2011 (about 82,000 acre-feet) and compared it to an older analysis done for year 2008 (about 36,000 acre-feet). A private database compiling state information and providing water use is complemented by a survey of the industry. Industry survey is the only way to access fresh water consumption estimated to be only a fraction of the total water use because of reuse of flowback water, use of recycled water from treatment plants and produced water, and use of brackish water. We analyzed these different components of the HF budget as well as their source, surface water vs. groundwater, with a focus on impacts on aquifers and groundwater resources.

Nicot, J.; Reedy, R. C.; Costley, R.

2012-12-01

230

Detecting Low-Frequency Seismic Signals From Surface Microseismic Monitoring of Hydraulic Fracturing of a Tight-Sand Gas Reservoir  

NASA Astrophysics Data System (ADS)

For both surface and downhole microseismic monitoring, generally geophones with resonance frequency greater than 4.5 Hz are used. Therefore, useful information below 4.5 Hz may not be detected. In a recent experiment, we installed14 3-component broadband seismic sensors on the surface to monitor the process of hydraulic fracturing of tight sand gas reservoirs. The sensor has a broad frequency range of 30 s to 100 Hz with a very high sensitivity of 2400 m/v/s. The reservoirs are located around 1.5 km depth. There are two fracturing stages along a vertical well, lasting for about 2 hours. We recorded the data continuously during the fracturing process at a sampling rate of 50 Hz. From time-frequency analysis of continuous data, we found some high-energy signals at resonance frequencies between 10 and 20 Hz and a relatively weaker signal at a resonance frequency of ~27 Hz during the hydraulic fracturing. These signals with various resonance frequencies are likely caused by vibrations of high-pressure pipes. In addition to the resonance frequencies, the time-frequency analysis also showed consistent low frequency signals between 3 and 4 Hz at different time. The move-out analysis showed that these signals traveled at shear-wave speeds. We have detected 77 effective low frequency events during the 2-hour hydraulic fracturing process, among which 42 were located by a grid-search location method. The horizontal distribution of the events aligns with the maximum horizontal compressive stress direction. Because of the uncertainty in the velocity model, the low-frequency seismic events are not located in the fracturing depths. Recently, long-period, long-duration seismic events in the frequency band of 10 to 80 Hz were detected during hydraulic fracture stimulation of a shale gas reservoir, which may be caused by slow slip along faults/fractures (Das and Zoback, 2011). In the active volcanic areas, monochromatic events that are related to circulation of hydrothermal fluids are often detected. Our detected low frequency seismic signals have waveforms and frequency contents resembling the monochromatic events detected in volcanic areas, therefore we believe they are also likely caused by movement of fracturing fluids.

Yu, H.; Zhang, H.; Zeng, X.

2013-12-01

231

Computer simulation of effective viscosity of fluid-proppant mixture used in hydraulic fracturing  

E-print Network

The paper presents results of numerical experiments performed to evaluate the effective viscosity of a fluid-proppant mixture, used in hydraulic fracturing. The results, obtained by two complimenting methods (the particle dynamics and the smoothed particle hydrodynamics), coincide to the accuracy of standard deviation. They provide an analytical equation for the dependence of effective viscosity on the proppant concentration, needed for numerical simulation of the hydraulic fracture propagation.

Kuzkin, Vitaly A; Linkov, Aleksandr M

2013-01-01

232

Characterisation of hydraulic fractures in limestones using X-ray microtomography  

E-print Network

Hydraulic tension fractures were produced in porous limestones using a specially designed hydraulic cell. The 3D geometry of the samples was imaged using X-ray computed microtomography before and after fracturation. Using these data, it was possible to estimate the permeability tensor of the core samples, extract the path of the rupture and compare it to the heterogeneities initially present in the rock.

Renard, Francois; Desrues, Jacques; Plougonven, Erwan; Ougier-Simonin, Audrey

2006-01-01

233

[Effects of invertebrate bioturbation on vertical hydraulic conductivity of streambed for a river].  

PubMed

Streambed hydraulic conductivity is a key factor influencing water exchange between surface water and groundwater. However, the streambed invertebrate bioturbation has a great effect on the hydraulic conductivity. In order to determine the impact of invertebrate bioturbation on streambed hydraulic conductivity, the investigation of invertebrate bioturbation and in-situ test of vertical hydraulic conductivity of streambed are simultaneously conducted at five points along the main stream of the Weihe River. Firstly, correlation between the streambed vertical hydraulic conductivity and grain size distribution is analyzed. Secondly, type and density of the invertebrate and their correlation to hydraulic conductivity are determined. Finally, the effect of invertebrate bioturbation on the streambed hydraulic conductivity is illustrated. The results show that the vertical hydraulic conductivity and biological density of invertebrate are 18.479 m x d(-1) and 139 ind x m(-2), respectively for the Caotan site, where sediment composition with a large amount of sand and gravel particles. For Meixian site, the sediment constitutes a large amount of silt and clay particles, in which the vertical hydraulic conductivity and biological density of invertebrate are 2.807 m x d(-1) and 2 742 ind x m(-2) respectively. Besides, for the low permeability of four sites (Meixian, Xianyang, Lintong and Huaxian), grain size particles are similar while the vertical hydraulic conductivity and biological density of invertebrate are significantly different from one site to another. However, for each site, the vertical hydraulic conductivity closely related to biological density of invertebrate, the Pearson correlation coefficient is 0.987. It can be concluded that both grain size particles and invertebrate bioturbation influence sediment permeability. For example, higher values of streambed hydraulic conductivity from strong permeability site mainly due to the large amount of large-size particles and that from low permeability site is the main results from higher biological density of invertebrate. Large amount of grain size particles can expand pore space and the invertebrate bioturbation can destroy clogging sediment and enhance sediment permeability. PMID:24455934

Ren, Chao-Liang; Song, Jin-Xi; Yang, Xiao-Gang; Xue, Jian

2013-11-01

234

Mechanical and hydraulic behavior of a rock fracture under shear deformation  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

235

Fracture analysis in the south-western Corinth rift (Greece) and implications on fault hydraulic behavior  

Microsoft Academic Search

This paper reviews the data concerning the fracture network and the hydraulic characteristics of faults in an active zone of the Gulf of Corinth. Pressure gap measured through fault planes shows that in this area the active normal faults (Aigion, Helike) act, at least temporarily and locally, as transversal seal. The analysis of the carbonate cements in the fractures on

Luca Micarelli; Isabelle Moretti; Manon Jaubert; Hakim Moulouel

2006-01-01

236

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

E-print Network

-off dominated. We demonstrate the ability of our cohesive zone model in simulating the hydraulic fracture in all-mechanical coupling 1. Introduction The propagation of fluid-driven fractures in a porous medium is an im- portant or radioactive waste [30], geothermal Corresponding author Email address: benoit.carrier@enpc.fr (Benoit Carrier

Paris-Sud XI, Université de

237

A new microseismic location method accounting for the influence of the hydraulic fracturing process  

NASA Astrophysics Data System (ADS)

In the hydraulic fracturing process, the velocity model of traditional inversion is usually constructed by well logs, seismic data or calibration shots. The variation of pore pressure and fractures in this process has a major influence on the velocity. However, this influence is usually ignored in the velocity estimation model. In this paper, we propose a new microseismic location method that accounts for the influence of hydraulic fracturing on velocity. Firstly, we simulate the 3D hydraulic fracturing process based on mass conservation, the seepage equation and fracture mechanics. Then the equivalent velocity model is constructed using the Coates-Schoenberg method and fracture compliances. The 3D ray-tracing method is applied to forward-model the microseismic data and traditional inversion methods are applied to locate events and analyse the inversion error. Finally, we introduce a new method, called the equivalent velocity inversion method (EVIM), taking into account the influence of the fracturing process. The simulation results show that the hydraulic fracturing process affects the velocity and thus makes the inversion accuracy of the same receiver array vary considerably with the sources in the traditional methods. The new EVIM can effectively reduce the inversion error.

Zhang, Xiaolin; Zhang, Feng; Li, Xiangyang; Chen, Shuangquan

2013-06-01

238

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

239

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

240

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

Microsoft Academic Search

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

David D. Pollard

1976-01-01

241

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

242

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

E-print Network

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

Peirce, Anthony

243

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

244

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

E-print Network

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

Boyer, Edmond

245

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

NASA Astrophysics Data System (ADS)

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

Nicot, J.; Scanlon, B. R.

2013-12-01

246

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

Microsoft Academic Search

A hydrostructural domain approach was tested and validated in fractured bedrock aquifers of the Gulf Islands, British Columbia\\u000a (BC), Canada. Relative potential hydraulic properties for three hydrostructural domains in folded and faulted sedimentary\\u000a rocks were derived using stochastically generated fracture data and hybrid discrete fracture network-equivalent porous media\\u000a (DFN-EPM) modelling. Model-derived relative potential transmissivity values show good spatial agreement with

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

2008-01-01

247

Sizing of a hot dry rock reservoir from a hydraulic fracturing experiment  

SciTech Connect

Hot dry rock (HDR) reservoirs do not lend themselves to the standard methods of reservoir sizing developed in the petroleum industry such as the buildup/drawdown test. In a HDR reservoir the reservoir is created by the injection of fluid. This process of hydraulic fracturing of the reservoir rock usually involves injection of a large volume (5 million gallons) at high rates (40BPM). A methodology is presented for sizing the HDR reservoir created during the hydraulic fracturing process. The reservoir created during a recent fracturing experiment is sized using the techniques presented. This reservoir is then investigated for commercial potential by simulation of long term power production. 5 refs., 7 figs.

Zyvoloski, G.

1985-01-01

248

Numerical simulation of surface and downhole deformation induced by hydraulic fracturing  

NASA Astrophysics Data System (ADS)

Tiltmeter mapping technology infers hydraulic fracture geometry by measuring fracture-induced rock deformation, which recorded by highly sensitive tiltmeters placed at the surface and in nearby observation wells. By referencing Okada's linear elastic theory and Green's function method, we simulate and analyze the surface and downhole deformation caused by hydraulic fracturing using the homogeneous elastic half-space model and layered elastic model. Simulation results suggest that there is not much difference in the surface deformation patterns between the two models, but there is a significant difference in the downhole deformation patterns when hydraulic fracturing penetrates a stratum. In such cases, it is not suitable to assume uniform elastic half-space when calculating the downhole deformation. This work may improve the accuracy and reliability of the inversion results of tiltmeter monitoring data.

He, Yi-Yuan; Zhang, Bao-Ping; Duan, Yu-Ting; Xue, Cheng-Jin; Yan, Xin; He, Chuan; Hu, Tian-Yue

2014-03-01

249

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

250

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

251

Determination of fracture and reservoir properties using an automatic history matching technique for wells with finite-conductivity vertical fractures  

E-print Network

and reservoir performance analyses of the field. Transient pressure behavior of wells with finite-conductivity 1-7 vertical fractures has been studied by many authors. Several methods have been proposed to determine the created fracture length, fracture.... They also discussed how the fracture charateristics may not be determined when wellbore storage effects are present. In September 1981, Cinco and Samaniego presented an 7 analytical solution for analysis of the transient behavior of finite...

Santhanam, Kalakad Sundhareswaraiyer

2012-06-07

252

Finite element modeling of hydraulic fracturing in 3D  

E-print Network

Mar 22, 2013 ... wanted effects. like for instance. leakage of natural gas into the .... It is taken to be the result of time- and temperature- dependent ..... ture growth. Continuous fracture .... one new layer of cells during each fracture event. The.

2013-03-22

253

Cyclic steaming of tar sands through hydraulically induced fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numerical modeling. Fracture radii of 100 feet and half-lengths of 250 feet with fracture surface areas of 30,000 to 70,000 square feet were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of

Deitrich

1983-01-01

254

Cyclic steaming of tar sands through hydraulically induced fractures  

SciTech Connect

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numerical modeling. Fracture radii of 100 feet and half-lengths of 250 feet with fracture surface areas of 30,000 to 70,000 square feet were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation.

Deitrich, J.K.

1983-03-01

255

Cyclic steaming of tar sands through hydraulically induced fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numeric modeling. Fracture radii of 100 ft and half-lengths of 250 ft with fracture surface areas of 30,000 to 70,000 sq ft were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of

Dietrich

1983-01-01

256

Cyclic steaming of tar sands through hydraulically induced fractures  

SciTech Connect

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numeric modeling. Fracture radii of 100 ft and half-lengths of 250 ft with fracture surface areas of 30,000 to 70,000 sq ft were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation.

Dietrich, J.K.

1983-01-01

257

Estimation of REV size and three-dimensional hydraulic conductivity tensor for a fractured rock mass through a single well packer test and discrete fracture fluid flow modeling  

Microsoft Academic Search

A new methodology is presented to determine the representative elementary volume (REV) size and three-dimensional (3-D) hydraulic conductivity tensor for a fractured rock mass. First, a 3-D stochastic fracture network model was built and validated for a gneissic rock mass based on the fracture data mapped from scanline surveys at the site. This validated fracture network model was combined with

M Wang; P. H. S. W Kulatilake; J Um; J Narvaiz

2002-01-01

258

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

E-print Network

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

Shabelansky, Andrey Hanan

2012-01-01

259

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

E-print Network

Better understanding and control of crack growth direction during hydraulic fracturing are essential for enhancing productivity of geothermal and petroleum reservoirs. Structural analysis of fracture propagation and impact on fluid flow is a...

Min, Kyoung

2013-07-16

260

Single-well interference slug tests to assess the vertical hydraulic conductivity of unconsolidated aquifers  

NASA Astrophysics Data System (ADS)

SummaryMeaningful understanding of flow and solute transport in general requires the knowledge of hydraulic conductivity and its anisotropy. Various field methods allow the measurement of the horizontal component (Kh), but vertical hydraulic conductivity (Kv) is rarely measured, for lack of practical field tests. This paper proposes vertical interference slug tests, an adaptation of inter-well interference slug tests to a single well, for the efficient field measurement of Kv. The test is carried out in a single well between a stress and an observation interval that are vertically isolated with a three-packer assembly. An instantaneous pressure pulse is induced in the stress interval and resulting drawdowns are recorded in both the stress and the observation intervals. In a proof-of-concept field study, 12 vertical interference tests were carried out sequentially along a fully-screened well across a moderately heterogeneous and highly anisotropic aquifer made up of littoral silts and sands. A direct-push method was used to install the well, which was completed without sand-pack to allow the natural collapse of sediments in the thin annular space around the screen. Direct-push wells allow the measurement of in situ hydraulic properties of sediments and minimize well construction interferences with hydraulic tests. Drawdowns measured in stress and observation intervals of multiple tests were simultaneously inverted numerically to reconstruct heterogeneous profiles of Kh, hydraulic conductivity anisotropy (Kv/Kh), and specific storage (Ss). Results were validated by comparison of observed versus predicted drawdowns and with field and laboratory measurements of Kh and Kv made along the tested well. Results indicate that the profile of Kv values obtained with vertical interference slug tests follows a similar pattern with depth than the profile with lab measurements made with a permeameter on soil samples collected in the same intervals as the interference tests, which demonstrates that vertical interference slug tests could provide an efficient method for the field measurement of well-scale Kv values.

Paradis, Daniel; Lefebvre, René

2013-01-01

261

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

262

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

PubMed

Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use. PMID:19664046

Fritz, Brad G; Mackley, Rob D

2010-01-01

263

Evaluating vertical variability analysis (VVA) for estimating the hydraulic conductivity, specific yield, and transmissivity of four simulated geologic configurations  

Microsoft Academic Search

Aquifer systems derived from fluvial, eolian, glacial, or mass movement processes may have considerable vertical and areal variability in saturated thickness, hydraulic conductivity, specific yield, and bed thickness. Frequently, hydraulic data from aquifer tests are not readily available, whereas lithologic and grain-size information from drillers' logs is generally abundant. Therefore, the vertical variability method was devised to evaluate the aquifer

G. D. Witt; K. E. Kolm

1992-01-01

264

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

PubMed

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

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

2009-01-26

265

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

USGS Publications Warehouse

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 (??PN2) 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. ?? 2008 Elsevier B.V. All rights reserved.

Wishart, D.N.; Slater, L.D.; Schnell, D.L.; Herman, G.C.

2009-01-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

267

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

NASA Astrophysics Data System (ADS)

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

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

2002-08-01

268

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

USGS Publications Warehouse

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

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

2002-01-01

269

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

270

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...

271

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

272

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

273

Rock deformation models and fluid leak-off in hydraulic fracturing  

NASA Astrophysics Data System (ADS)

Fluid loss into reservoir rocks during hydraulic fracturing is modelled via a poro-elastoplastic pressure diffusion equation in which the total compressibility is a sum of fluid, rock and pore space compressibilities. Inclusion of pore compressibility and porosity-dependent permeability in the model leads to a strong pressure dependence of leak-off (i.e. drainage rate). Dilation of the matrix due to fluid invasion causes higher rates of fluid leak-off. The present model is appropriate for naturally fractured and tight gas reservoirs as well as for soft and poorly consolidated formations whose mechanical behaviour departs from simple elastic laws. Enhancement of the leak-off coefficient by dilation, predicted by the new model, may help explain the low percentage recovery of fracturing fluid (usually between 5 and 50 per cent) in shale gas stimulation by hydraulic fracturing.

Yarushina, Viktoriya M.; Bercovici, David; Oristaglio, Michael L.

2013-09-01

274

The role of friction and secondary flaws on deflection and re-initiation of hydraulic fractures at orthogonal pre-existing fractures  

Microsoft Academic Search

In this study, we explore the nature of plane-strain hydraulic fracture growth in the presence of pre-existing fractures such as joints without or with secondary flaws. The 2-D plane-strain fracture studied can be taken as a cross-section through the short dimensions of an elongated 3-D fracture or as an approximate representation of the leading edge of a 3-D fracture where

Xi Zhang; Robert G. Jeffrey

2006-01-01

275

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

USGS Publications Warehouse

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

Hess, Alfred E.

1986-01-01

276

Failure of a gas well to respond to a foam hydraulic fracturing treatment  

SciTech Connect

Well No. 1 (not the real name of the well) is not producing gas at maximum capacity following a foam hydraulic fracturing treatment performed upon completion of the well in 1987. The failure of the stimulation treatment, which has affected other wells throughout the field, was due to a combination of three factors: (1) downward fracture growth and proppant settling during injection (2) embedment due to a high pressure drawdown in the wellbore during flowback procedures, and (3) poor cleanup of the fracture fluid due to high capillary pressures. The following are recommendations to help improve future fracturing treatments throughout the field: (1) Fracture at lower treating pressures; (2) Improve perforating techniques; (3) Change flowback procedures; and (4) Evaluate using N{sub 2} as a fracture fluid.

Rauscher, B.D.

1996-12-31

277

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

EPA Science Inventory

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

278

Vertical contaminant profiling of volatile organics in a deep fractured basalt aquifer  

SciTech Connect

Volatile organic compounds detected in ground water from wells at Test Area North (TAN) at the Idaho National Engineering Laboratory (INEL) prompted RCRA facility investigations in 1989 and 1990 and a CERCLA-driven RI/FS in 1992. In order to address ground water treatment feasibility, one of the main objectives of the 1992 remedial investigation was to determine the vertical extent of ground water contamination, where the principle contaminant of concern is trichloroethylene (TCE). It was hypothesized that a sedimentary interbed at depth in the fractured basalt aquifer could be inhibiting vertical migration of contaminants to lower aquifers. Due to the high cost of drilling and installation of ground water monitoring wells at this facility (greater than $100,000 per well), a real time method was proposed for obtaining and analyzing ground water samples during drilling to allow accurate ground water samples during drilling to allow accurate placement of well screens in zones of predicted VOC contamination. This method utilized an inflatable pump packer pressure transducer system interfaced with a datalogger and PC at land surface. This arrangement allowed for real time monitoring of hydraulic head above and below the packer to detect leakage around the packer during pumping and enabled collection of head data during pumping for estimating hydrologic properties.

Kaminsky, J.F.; Wylie, A.H.

1995-07-01

279

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

280

Theoretical relation between water flow rate in a vertical fracture and rock temperature in the surrounding massif  

NASA Astrophysics Data System (ADS)

A steady-state analytical solution is given describing the temperature distribution in a homogeneous massif perturbed by cold water flow through a discrete vertical fracture. A relation is derived to express the flow rate in the fracture as a function of the temperature measured in the surrounding rock. These mathematical results can be useful for tunnel drilling as it approaches a vertical cold water bearing structure that induces a thermal anomaly in the surrounding massif. During the tunnel drilling, by monitoring this anomaly along the tunnel axis one can quantify the flow rate in the discontinuity ahead before intersecting the fracture. The cases of the Simplon, Mont Blanc and Gotthard tunnels (Alps) are handled with this approach which shows very good agreement between observed temperatures and the theoretical trend. The flow rates before drilling of the tunnel predicted with the theoretical solution are similar in the Mont Blanc and Simplon cases, as well as the flow rates observed during the drilling. However, the absence of information on hydraulic gradients (before and during drilling) and on fracture specific storage prevents direct predictions of discharge rates in the tunnel.

Maréchal, Jean-Christophe; Perrochet, Pierre

2001-12-01

281

A Packer Test Design Utilizing a Discrete Fracture Network and Flow Model for the Determination of 3-D Hydraulic Conductivity Tensor in Fractured Rocks  

Microsoft Academic Search

The hydraulic behavior of a fractured rock mass depends on the orientation, size, intensity, aperture, and connectivity of the fractures. The common assumption of fluid flow through a geologic continuum could be invalid for a fractured rock mass in a specified scale. Even though the Representative Elementary Volume (REV) is small for porous media, it is most likely much larger

M. Wang

2001-01-01

282

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

E-print Network

and buildup data, Ramey treated non-Darcy flow as a rate-dependent skin effect. In the late 1960 ' s, emphasis on non-Darcy flow in the formation shifted to include non-Darcy flow in hydraulically created fractures. In a study of non-Darcy flow... in the formation by Wattenbarger and Ramey, 3 one of the conclusions was that non-Darcy flow is more common in the fracture than in the formation. Cooke4 developed a correlation for the beta factor which is applicable to fractured reservoirs. The correlation...

Hresko, Joanne Carol

2012-06-07

283

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

E-print Network

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

Patzek, Tadeusz W.

284

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

USGS Publications Warehouse

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

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

1994-01-01

285

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

286

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

287

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

288

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

289

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

290

Rock-Fluid Chemistry Impacts on Shale Hydraulic Fracture and Microfracture Growth  

E-print Network

The role of surface chemical effects in hydraulic fracturing of shale is studied using the results of unconfined compression tests and Brazilian tests on Mancos shale- cored at depths of 20-60 ft. The rock mineralogy, total organic carbon and cation...

Aderibigbe, Aderonke

2012-07-16

291

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

292

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

E-print Network

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

Peirce, Anthony

293

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

E-print Network

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

Peirce, Anthony

294

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

2013-09-01

295

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

296

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

297

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

298

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

E-print Network

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

Paris-Sud XI, Université de

299

METHOD DEVELOPMENT FOR DETERMINING THE HYDRAULIC CONDUCTIVITY OF FRACTURED POROUS MEDIA  

SciTech Connect

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

Dixon, K.

2013-09-30

300

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

301

A numerical study on the correlation between fracture transmissivity, hydraulic aperture and transport aperture  

NASA Astrophysics Data System (ADS)

Quantitative evaluation of the groundwater velocity in the fractures is a key part of contaminants transport assessment especially in the radioactive waste disposal programs. In a hydrogeological model such as the discrete fracture network model, the transport aperture of water conducting fracture is one of the important parameters for evaluating groundwater velocity. Tracer tests that measure velocity (or transport aperture) are few compared with flow tests that measure transmissivity (or hydraulic aperture). Thus it is useful to estimate transport properties from flow properties. It is commonly assumed that flow and transport aperture are the same, and that aperture is related to the cube root of transmissivity by the parallel-plate analog. Actual field experiments, however, show transport and hydraulic apertures are not always the same, and that transport aperture relates to an empirical constant times the square root of transmissivity. Compared with these field results, the cubic law underestimates transport aperture and overestimates velocity. A possible source of this discrepancy is in-plane heterogeneity of aperture and transmissivity. To study this behavior, numerical simulations using MAFIC were conducted for a single fracture model with a heterogeneous aperture distribution. The simulations varied three parameters - the mean geometrical aperture, JRC (Joint Roughness Coefficient), and the contact area ratio (fracture contact area divided by total fracture area). For each model we determined the equivalent transmissivity and cubic-law aperture under steady flow conditions. Then we simulated mass transport using particle tracking through the same fracture. The transport aperture was estimated from the particle peak arrival time at the downstream boundary. The results show that the mean geometrical aperture is the most sensitive parameter among the three variable parameters in this study. It is also found that the contact area ratio affects transmissivity more than the JRC, and while the JRC strongly affects the velocity and transport aperture. Based on these results, a correlation between the transmissivity, the hydraulic conductivity and the transport aperture will be discussed.

Sawada, A.; Takebe, A.; Sakamoto, K.

2006-12-01

302

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...

303

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

304

The effect of vertical fractures on the behavior of a stratified reservoir under waterflood  

E-print Network

THE EFFECT OF VERTICAL FRACTURES ON THE BEHAVIOR OF A STRATIFIED RESERVOIR UNDER WATERFLOOD A Thesis Bobby E Pettitt Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in Partial i...'ulfillment of the requirements for the degree of MASTER OF SCIENCE August~ 1963 Major Sub]ect: Petroleum Engineering THE EFFECT GF VERTICAL FRACTURES ON THE BEHAVIOR OF A STRATIFIED RESERVOIR UNDER WATERFLOOD A Thesis by Bobby E. Pettitt Approved as to style...

Pettitt, Bobby Eugene

2012-06-07

305

Surgical rehabilitation of free fibula graft fracture under local anesthesia with posteriorly directed vertical alveolar distractor.  

PubMed

Reconstruction of the mandible with a free fibular graft is one of the most common treatment choices following tumor resection. But as the graft is often vertically deficient, pathological fracture may occur because of occlusal forces after prosthetic rehabilitation. Distraction osteogenesis can be a good choice for the repair of the fibular flap. In this report, a case of fractured fibula flap after 7 years, rehabilitated with a posteriorly directed vertical distractor, will be presented. PMID:25278664

Baykul, Timuçin; Ayd?n, M As?m; F?nd?k, Yavuz; Türkaslan, S Süha

2014-08-01

306

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

307

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

NASA Astrophysics Data System (ADS)

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

Huisman, J. A.; Mboh, C.; Rings, J.; Vrugt, J. A.; Vereecken, H.

2011-12-01

308

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

USGS Publications Warehouse

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

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

1987-01-01

309

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

310

The use of slug tests to describe vertical variations in hydraulic conductivity  

USGS Publications Warehouse

Multilevel slug tests provide one means of obtaining estimates of hydraulic conductivity on a scale of relevance for contaminant transport investigations. A numerical model is employed here to assess the potential of multilevel slug tests to provide information about vertical variations in hydraulic conductivity under conditions commonly faced in field settings. The results of the numerical simulations raise several important issues concerning the effectiveness of this technique. If the length of the test interval is of the order of the average layer thickness, considerable error may be introduced into the conductivity estimates owing to the effects of adjoining layers. The influence of adjoining layers is dependent on the aspect ratio (length of test interval/well radius) of the tesy interval and the flow properties of the individual layers. If a low-permeability skin is present at the well, the measured vertical variations will be much less than the actual variations, owing to the influence of the skin conductivity on the parameter estimates. A high-permeability skin can also produce apparent vertical variations that are much less than the actual, owing to water flowing vertically along the conductive skin. In cases where the test interval spans a number of layers, a slug test will yield an approximate thickness-weighted average of the hydraulic conductivities of the intersected layers. In most cases, packer circumvention should not be a major concern when packers of 0.75 m or longer are employed. Results of this study are substantiated by recently reported field tests that demonstrate the importance of well emplacement and development activities for obtaining meaningful estimates from a program of multilevel slug tests. ?? 1994.

Butler, Jr. , J. J.; Bohling, G. C.; Hyder, Z.; McElwee, C. D.

1994-01-01

311

Propagation of a penny-shaped hydraulic fracture parallel to the free-surface of an elastic half-space  

Microsoft Academic Search

In this paper we analyze the problem of a penny-shaped hydraulic fracture propagating parallel to the free-surface of an elastic half-space. The fracture is driven by an incompressible Newtonian fluid injected at a constant rate at the center of the fracture. The flow of viscous fluid in the fracture is governed by the lubrication equation, while the crack opening and

Xi Zhang; Emmanuel Detournay; Rob Jeffrey

2002-01-01

312

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

313

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

SciTech Connect

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

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

2013-11-19

314

Fracture of colloidal single-crystal films fabricated by controlled vertical drying deposition Ding Lan,1,*,  

E-print Network

Fracture of colloidal single-crystal films fabricated by controlled vertical drying deposition He­13 . Cracks emerging during colloidal film deposition destroy its periodic structure 14­16 . Unfortunately, USA Received 6 April 2010; published 2 September 2010 Controlled vertical drying deposition method

Volinsky, Alex A.

315

Low permeability gas reservoir production using large hydraulic fractures  

E-print Network

IN 700 ? 4IB. G PSI/DAY DRAW DOWN 04 ~ 4332. 4 MCF / OAY + d 5 PSI/ OAY DRAW DOWN Qq ~ 627. B MCF/OAY 600 0 I 2 3 4 5 6 7 8 9 I 0 I I I 2 I 3 l4 I 5 l6 I 7 i8 TIME ( HRS) lP Z C X IO IL 0 cn ~ M O lal g M IO Is 20 0 IOOO 2000 3000 4000... at the end of the ten years monitored. The income is not discounted and assumes s. gas price of 20 cents per MCF. SUMMARY AND CONCLUSIONS 7 Using the concept of fracturing presented by Wiisey and s. 12 numerical model by Morse, the effect of long...

Holditch, Stephen A

2012-06-07

316

A nonlocal model for fluid-structure interaction with applications in hydraulic fracturing  

E-print Network

Modeling important engineering problems related to flow-induced damage (in the context of hydraulic fracturing among others) depends critically on characterizing the interaction of porous media and interstitial fluid flow. This work presents a new formulation for incorporating the effects of pore pressure in a nonlocal representation of solid mechanics. The result is a framework for modeling fluid-structure interaction problems with the discontinuity capturing advantages of an integral based formulation. A number of numerical examples are used to show that the proposed formulation can be applied to measure the effect of leak-off during hydraulic fracturing as well as modeling consolidation of fluid saturated rock and surface subsidence caused by fluid extraction from a geologic reservoir. The formulation incorporates the effect of pore pressure in the constitutive description of the porous material in a way that is appropriate for nonlinear materials, easily implemented in existing codes, straightforward in i...

Turner, Daniel Z

2012-01-01

317

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

E-print Network

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

Song, Fuxian

2010-01-01

318

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

Federal Register 2010, 2011, 2012, 2013

...INFORMATION: Underground injection of fluids through wells is subject to the requirements...a]ny underground injection, except into a well authorized by rule or except...permitting hydraulic fracturing injection wells where diesel fuels...

2012-07-09

319

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

NASA Astrophysics Data System (ADS)

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

Alzarouni, Asim

320

Rock mechanics issues and research needs in the disposal of wastes in hydraulic fractures  

SciTech Connect

The proposed rock mechanics studies outlined in this document are designed to answer the basic questions concerning hydraulic fracturing for waste disposal. These questions are: (1) how can containment be assured for Oak Ridge or other sites; and (2) what is the capacity of a site. The suggested rock mechanics program consists of four major tasks: (1) numerical modeling, (2) laboratory testing, (3) field testing, and (4) monitoring. These tasks are described.

Doe, T.W.; McClain, W.C.

1984-07-01

321

Characterization and reservoir evaluation of a hydraulically fractured, shaly gas reservoir  

E-print Network

as to style and content by S. W. Poston (Chair of committee) Ronald M. Brimhall (Member) Robert R. Berg (Member) Ken Hall (Interin Head of Department) December 1991 ABSTRACT Characterization and Reservoir Evaluation of a Hydraulically Fractured.... Buildup tests will be analyzed using different approaches to calculate permeability and reservoir average pressure to check these results. It is expected to define a reservoir pressure behavior model which will improve the accuracy of the reservoir...

Santiago Molina, Cesar Alfonso

2012-06-07

322

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

323

Role of shale thickness on vertical connectivity of fractures: application of crack-bridging theory to the Austin Chalk, Texas  

Microsoft Academic Search

Contrasting material properties of alternating chalk and shale layers control vertical connectivity of fractures. Our field observations within the Austin Chalk, Texas indicate that: (1) the majority of vertical fractures occur in chalk layers and abut against contacts with shale layers, (2) thicker shale layers have greater resistance to fracture propagation than thinner shale layers. From these observations we hypothesize

Peggy Rijken; Michele L. Cooke

2001-01-01

324

Comparison of vertical hydraulic conductivity in a streambed-point bar system of a gaining stream  

NASA Astrophysics Data System (ADS)

SummaryVertical hydraulic conductivities (Kv) of both streambed and point bars can influence water and solute exchange between streams and surrounding groundwater systems. The sediments in point bars are relatively young compared to the older sediments in the adjacent aquifers but slightly older compared to submerged streambeds. Thus, the permeability in point bar sediments can be different not only from regional aquifer but also from modern streambed. However, there is a lack of detailed studies that document spatial variability of vertical hydraulic conductivity in point bars of meandering streams. In this study, the authors proposed an in situ permeameter test method to measure vertical hydraulic conductivity of the two point bars in Clear Creek, Nebraska, USA. We compared the Kv values in streambed and adjacent point bars through 45 test locations in the two point bars and 51 test locations in the streambed. The Kv values in the point bars were lower than those in the streambed. Kruskal-Wallis test confirmed that the Kv values from the point bars and from the channel came from two statistically different populations. Within a point bar, the Kv values were higher along the point bar edges than those from inner point bars. Grain size analysis indicated that slightly more silt and clay particles existed in sediments from inner point bars, compared to that from streambed and from locations near the point bar edges. While point bars are the deposits of the adjacent channel, the comparison of two groups of Kv values suggests that post-depositional processes had an effect on the evolution of Kv from channel to point bars in fluvial deposits. We believed that the transport of fine particles and the gas ebullition in this gaining stream had significant effects on the distribution of Kv values in a streambed-point bar system. With the ageing of deposition in a floodplain, the permeability of point bar sediments can likely decrease due to reduced effects of the upward flow and gas ebullition.

Dong, Weihong; Chen, Xunhong; Wang, Zhaowei; Ou, Gengxin; Liu, Can

2012-07-01

325

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

NASA Astrophysics Data System (ADS)

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

Lu, Rong

326

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

PubMed

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

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

2014-10-01

327

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

PubMed

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

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

2014-11-01

328

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

329

Edit paper Methods for Large Scale Hydraulic Fracture Monitoring  

E-print Network

In this paper we propose computationally efficient and robust methods for estimating the moment tensor and location of micro-seismic event(s) for large search volumes. Our contribution is two-fold. First, we propose a novel joint-complexity measure, namely the sum of nuclear norms which while imposing sparsity on the number of fractures (locations) over a large spatial volume, also captures the rank-1 nature of the induced wavefield pattern. This wavefield pattern is modeled as the outer-product of the source signature with the amplitude pattern across the receivers from a seismic source. A rank-1 factorization of the estimated wavefield pattern at each location can therefore be used to estimate the seismic moment tensor using the knowledge of the array geometry. In contrast to existing work this approach allows us to drop any other assumption on the source signature. Second, we exploit the recently proposed first-order incremental projection algorithms for a fast and efficient implementation of the resulting...

Ely, Gregory

2013-01-01

330

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

Microsoft Academic Search

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

Shunji Sasaki

1998-01-01

331

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

E-print Network

FRACTURED GAS WELL ANALYSIS - EVALUATION OF IN SITU RESERVOIR PROPERTIES OF LOW PERMEABILITY GAS WELLS STIMULATED BY FINITE CONDUCTIVITY HYDRAULIC FRACTURES A Thesis by CHARLES ADOIZA MAKOJU Submitted to the Graduate College of Texas AQ1... University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1978 Major Subject: Petroleum Engineering FRACTURED GAS NELL ANALYSIS - EVALUATION OF IN SITU RESERVOIR PROPERTIES OF LOW PERMEABILITY GAS HELLS STIMULATED...

Makoju, Charles Adoiza

2012-06-07

332

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

333

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

SciTech Connect

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

David S. Schechter

2004-10-10

334

Field applications of cryogenic nitrogen as a hydraulic-fracturing fluid  

SciTech Connect

New techniques allow liquid nitrogen to be delivered safely to a moderate-depth formation at typical fracturing rates and cryogenic temperatures while protecting the casing from damage. This process provides a thermal shock to the reservoir rock that physically alters the fracture walls to prevent closure of hydraulically or thermally induced fractures. The results of this field project indicate that use of cryogenic nitrogen in refracture applications appears to reduce the damage caused by gel filter-cake residue from earlier fracturing treatments successfully. Carbon-steel alloys used for surface-iron manifolding, wellhead configuration, and wellbore tubulars cannot withstand even very-short-term exposure to cryogenic temperatures. All stainless-steel surface piping, manifolding, and wellhead components were constructed, and free-hanging fiberglass tubing was used to protect the casing from thermal-shock damage. Four coalbed-methane (CBM) wells and a tight sandstone reservoir were successfully fracture stimulated by use of cryogenic-nitrogen treatments. Standard oilfield nitrogen pumping units were modified to deliver either high-pressure liquid nitrogen or vaporized nitrogen gas. Initial post-fracture response was very good in all five wells. Long-term production enhancement was achieved in only two of the wells. This process has not been applied as an initial stimulation treatment on a new well.

NONE

1998-03-01

335

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

PubMed

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

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

2014-06-01

336

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

337

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

338

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

E-print Network

A comparison of microseismicity induced by gel-proppant- and water-injected hydraulic fractures induced during a series of hydraulic fracture completions within the Cotton Valley formation of East Texas controlled by the natural fracture geometry and independent of treatment design. By implication, we expect

339

Seepage forces, important factors in the formation of horizontal hydraulic1 fractures and bedding-parallel fibrous veins ("beef" and "cone-in-cone")2  

E-print Network

1 Seepage forces, important factors in the formation of horizontal hydraulic1 fractures and bedding24 may lead, either to tensile hydraulic fracturing, or to dilatant shear failure. We suggest that25 Terzaghi's concepts, leads to the conclusion that, for the18 fractures to be horizontal, either the rock

Paris-Sud XI, Université de

340

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

USGS Publications Warehouse

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

Paillet, F.L.

1993-01-01

341

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

342

Deciphering transmissivity and hydraulic conductivity of the aquifer by vertical electrical sounding (VES) experiments in Northwest Bangladesh  

NASA Astrophysics Data System (ADS)

The vertical electrical soundings (VESs) are carried out in 24 selective locations of Chapai-Nawabganj area of northwest Bangladesh to determine the transmissivity and hydraulic conductivity of the aquifer. Initially, the transmissivity and hydraulic conductivity are determined from the pumping data of nearby available production wells. Afterwards, the T and K are correlated with geoelectrical resistance and the total resistivity of the aquifer. The present study deciphers the functional analogous relations of the geoelectrical resistance with the transmissivity and the total resistivity with the hydraulic conductivity of the aquifer in northwest Bangladesh. It has been shown that the given equations provide reasonable values of transmissivity and hydraulic conductivity where pumping test information is unavailable. It can be expected that the aquifer properties viz. transmissivity and hydraulic conductivity of geologically similar area can be determined with the help of the obtained equations by conducting VES experiments.

Sattar, Golam Shabbir; Keramat, Mumnunul; Shahid, Shamsuddin

2014-06-01

343

Hydraulics.  

ERIC Educational Resources Information Center

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

Engelbrecht, Nancy; And Others

344

Use of a speed equation for numerical simulation of hydraulic fractures  

E-print Network

The paper treats the propagation of a hydraulically driven crack. We explicitly write the local speed equation, which facilitates using the theory of propagating interfaces. It is shown that when neglecting the lag between the liquid front and the crack tip, the lubrication PDE yields that a solution satisfies the speed equation identically. This implies that for zero or small lag, the boundary value problem appears ill-posed when solved numerically. We suggest e - regularization, which consists in employing the speed equation together with a prescribed BC on the front to obtain a new BC formulated at a small distance behind the front rather than on the front itself. It is shown that - regularization provides accurate and stable results with reasonable time expense. It is also shown that the speed equation gives a key to proper choice of unknown functions when solving a hydraulic fracture problem numerically.

Linkov, Alexander M

2011-01-01

345

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

PubMed

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

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

2014-06-01

346

A numerical investigation to illustrate the consequences of hydraulic connections between granular and fractured-rock aquifers  

NASA Astrophysics Data System (ADS)

Natural or artificial hydraulic connections between a granular aquifer in contact with a fractured-rock aquifer can have significant physical and chemical impacts at both a local and a regional scale. In this study, numerical simulations are conducted in order to illustrate the hydrogeological consequences of such hydraulic relationships. The numerical investigation, based on a conceptual model, focuses on the effects of the hydraulic connections when conducting a pumping test in a well that is set into a granular confined aquifer overlying a fractured-rock aquifer which presents a few fractures directly connected to the granular aquifer. It is illustrated that when interpreting the pumping test with the conventional methods consisting of plotting the drawdown versus time, a bias is introduced on the estimation of the transmissivity of the granular aquifer due to groundwater flowing from the fractured-rock aquifer via connecting fractures. However, it is underlined that plotting drawdown log-derivative versus time helps to diagnose the existence of these hydraulic relationships and therefore avoids committing a bias on the transmissivity estimation of the granular aquifer. Numerical simulation results also illustrate that hydraulic connections between the two aquifers can have significant impacts on the hydrogeochemical signature of the granular aquifer under investigation.

Chesnaux, Romain; Rafini, Silvain; Elliott, Annie-Pier

2012-12-01

347

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

E-print Network

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

Ely, Gregory

2013-01-01

348

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

E-print Network

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

Grassl, Peter; Gallipoli, Domenico; Wheeler, Simon J

2014-01-01

349

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

350

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

351

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

SciTech Connect

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

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

2013-01-01

352

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.

353

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

NASA Astrophysics Data System (ADS)

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

Tsai, Victor; Rice, James

2010-05-01

354

Massive hydraulic fracture test Cotton Valley Lime East Texas. Final report, 8 August 1978-31 July 1980  

SciTech Connect

This report summarizes the results of an active stimulation program on the Cotton Valley Lime as evaluated using reservoir production and pressure transient data. Using standard economic parameters and reservoir permeabilities determined by history matching, a detailed study was made to determine the well spacing and fracture length radius necessary for optimum development of the Fallon and North Personville Fields. In addition, the major details of designing and executing a super massive hydraulic fracture job are discussed in the appendix.

Kozik, H.G.; Holditch, S.A.; Kumar, A.

1980-08-01

355

Evaluating vertical variability analysis (VVA) for estimating the hydraulic conductivity, specific yield, and transmissivity of four simulated geologic configurations  

SciTech Connect

Aquifer systems derived from fluvial, eolian, glacial, or mass movement processes may have considerable vertical and areal variability in saturated thickness, hydraulic conductivity, specific yield, and bed thickness. Frequently, hydraulic data from aquifer tests are not readily available, whereas lithologic and grain-size information from drillers' logs is generally abundant. Therefore, the vertical variability method was devised to evaluate the aquifer properties for individual lithologic units based on drillers' information. These estimates provide vital information about aquifer characterization and are useful for hydraulic analysis and computer modeling. The purpose of this study was to evaluate the VVA for estimating the hydraulic conductivity, specific yield, and transmissivity of four simulated geological configurations. The objectives were to: (1) test the validity of VVA using the method of moments and the 0.5 criterion for relative center of gravity (RCOG); and (2) conduct a sensitivity analysis of material parameters relative to the RCOG. Results show that the 0.5 criterion for RCOG is valid only on a case-by-case basis depending primarily on the geometry of the geologic deposits, and secondarily on the thickness of individual geologic units. Sensitivity analyses reveal that the parameters of hydraulic conductivity and transmissivity are insensitive to changes in RCOG to plus or minus two to three orders of magnitude. Additional results indicate that the variance of RCOG for eolian, glacial, and incomplete two-cycle fluvial deposits is minimal as compared to the those for single and multiple fluvial cycles.

Witt, G.D. (Wright Water Engineers, Inc., Denver, CO (United States)); Kolm, K.E. (Colorado School of Mines, Golden, CO (United States))

1992-01-01

356

Temporal and vertical variation of hydraulic head in aquifers in the Edgewood area, Aberdeen Proving Ground, Maryland  

USGS Publications Warehouse

Water-level data and interpretations from previous hydrogeological studies conducted by the U.S. Geological Survey in the Edgewood Area of Aberdeen Proving Ground (APG), Maryland, were compared to determine similarities and differences among the aquifers. Because the sediments that comprise the shallow aquifers are discontinuous, the shallow ground-water-flow systems are local rather than extensive across the Edgewood Area. Hydrogeologic cross sections, hydrographs of water levels, and vertical gradients calculated from previous studies in the Canal Creek area, Graces Quarters, the O-Field area, Carroll Island, and the J-Field area, over periods of record ranging from 1 to 10 years during 1986-97, were used to determine recharge and discharge areas, connections between aquifers, and hydrologic responses of aquifers to natural and anthropogenic stress. Each of the aquifers in the study areas exhibited variation of hydraulic head that was attributed to seasonal changes in recharge. Upward hydraulic gradients and seasonal reversals of vertical hydraulic gradients between aquifers indicate the potential for local ground-water discharge from most of the aquifers that were studied in the Edgewood Area. Hydraulic head in individual aquifers in Graces Quarters and Carroll Island responded to offsite pumping during part of the period of record. Hydraulic head in most of the confined aquifers responded to tidal loading effects from nearby estuaries.

Donnelly, Colleen A.; Tenbus, Fredrick J.

1998-01-01

357

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

USGS Publications Warehouse

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

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

1985-01-01

358

Effects of plant roots on the hydraulic performance during the clogging process in mesocosm vertical flow constructed wetlands.  

PubMed

The aim of this study was to evaluate the effects of plant roots (Typha angustifolia roots) on the hydraulic performance during the clogging process from the perspective of time and space distributions in mesocosm vertical flow-constructed wetlands with coarse sand matrix. For this purpose, a pair of lab-scale experiments was conducted to compare planted and unplanted systems by measuring the effective porosity and hydraulic conductivity of the substrate within different operation periods. Furthermore, the flow pattern of the clogging process in the planted and unplanted wetland systems were evaluated by their hydraulic performance (e.g., mean residence time, short circuiting, volumetric efficiency, number of continuously stirred tank reactors, and hydraulic efficiency factor) in salt tracer experiments. The results showed that the flow conditions would change in different clogging stages, which indicated that plants played different roles related to time and space. In the early clogging stages, plant roots restricted the flow of water, while in the middle and later clogging stages, especially the later stage, growing roots opened new pore spaces in the substrate. The roots played an important role in affecting the hydraulic performance in the upper layer (0-30 cm) where the sand matrix had a larger root volume fraction. Finally, the causes of the controversy over plant roots' effects on clogging were discussed. The results helped further understand the effects of plant roots on hydraulic performance during the clogging process. PMID:24994107

Hua, G F; Zhao, Z W; Kong, J; Guo, R; Zeng, Y T; Zhao, L F; Zhu, Q D

2014-11-01

359

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

SciTech Connect

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

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

2010-05-01

360

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...

361

A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing in  

E-print Network

A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development: The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has

Jackson, Robert B.

362

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

363

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

364

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

365

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

366

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

PubMed Central

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

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

2015-01-01

367

Role of shale thickness on vertical connectivity of fractures: application of crack-bridging theory to the Austin Chalk, Texas  

NASA Astrophysics Data System (ADS)

Contrasting material properties of alternating chalk and shale layers control vertical connectivity of fractures. Our field observations within the Austin Chalk, Texas indicate that: (1) the majority of vertical fractures occur in chalk layers and abut against contacts with shale layers, (2) thicker shale layers have greater resistance to fracture propagation than thinner shale layers. From these observations we hypothesize both the resistance of shale to fracturing and the thickness of shale layers may inhibit fracture propagation across the shale and into the next chalk layer. We model crack propagation within a three-layered system (brittle chalk:fracture resistant shale:brittle chalk). The modeled crack extends across the shale, but closing tractions applied to the crack segment within the shale layer simulate resistance of shale to fracturing. The crack-tip lies a short distance within the unfractured chalk layer simulating a coplanar flaw with potential to propagate. If the stress intensity factor at the flaw exceeds the chalk fracture toughness, the crack propagates, thereby bridging and eventually rupturing the shale layer. For any chalk thickness, there is a critical shale thickness above which fractures cross the shale layer and below which fractures arrest at shale. Finite Element Method (FEM) analysis evaluates the influence of shale ductility within the chalk: shale: chalk system. Although remote and fluid pressure driven fractures produce identical stress intensity factors in elastic chalk/shale systems, lower driving stresses are required to propagate fluid pressure driven fractures through a system ductile shale layers than fractures under remote tension.

Rijken, Peggy; Cooke, Michele L.

2001-07-01

368

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

369

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

PubMed

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

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

2013-01-01

370

Digital Radiography with Computerized Conventional Monitors Compared to Medical Monitors in Vertical Root Fracture Diagnosis  

PubMed Central

Introduction Vertical root fracture (VRF) is a complication which is chiefly diagnosed radiographically. Recently, film-based radiography has been substituted with digital radiography. At the moment, there is a wide range of monitors available in the market for viewing digital images. The present study aims to compare the diagnostic accuracy, sensitivity and specificity of medical and conventional monitors in detection of vertical root fractures. Material and Methods In this in vitro study 228 extracted single-rooted human teeth were endodontically treated. Vertical root fractures were induced in 114 samples. The teeth were imaged by a digital charge-coupled device radiography using parallel technique. The images were evaluated by a radiologist and an endodontist on two medical and conventional liquid-crystal display (LCD) monitors twice. Z-test was used to analyze the sensitivity, accuracy and specificity of each monitor. Significance level was set at 0.05. Inter and intra observer agreements were calculated by Cohen’s kappa. Results Accuracy, specificity and sensitivity for conventional monitor were calculated as 67.5%, 72%, 62.5% respectively; and data for medical grade monitor were 67.5%, 66.5% and 68% respectively. Statistical analysis showed no significant differences in detecting VRF between the two techniques. Inter-observer agreement for conventional and medical monitor was 0.47 and 0.55 respectively (moderate). Intra-observer agreement was 0.78 for medical monitor and 0.87 for conventional one (substantial). Conclusion The type of monitor does not influence diagnosis of vertical root fractures. PMID:23412537

Tofangchiha, Maryam; Adel, Mamak; Bakhshi, Mahin; Esfehani, Mahsa; Nazeman, Pantea; Ghorbani Elizeyi, Mojgan; Javadi, Amir

2013-01-01

371

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

PubMed

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

Hammad, Mohammad; Qualtrough, Alison; Silikas, Nick

2007-06-01

372

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

373

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

374

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

PubMed

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

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

2011-03-01

375

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

USGS Publications Warehouse

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

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

2006-01-01

376

Hydraulic characterization of a fractured carbonatic aquifer using pumping test data - an example from the Eastern Alps (Austria)  

NASA Astrophysics Data System (ADS)

Water flow in fractured aquifers is strongly influenced by heterogenities including lithological and structural (fracture network) variability at various scales. This causes a dependency of the hydraulic properties on the investigation scale. Different hydraulic testing methods, such as pumping tests or packer tests, provide averaged hydraulic properties at larger scale or at local scale in the vicinity of the well. To investigate scale effects in a fractured, carbonatic aquifer piezometers with different distances to the pumping wells were used for monitoring the hydraulic head, the electric conductivity, and the water temperature. The investigated aquifer is built up by permomesozoic dolo-/ limestones of the Semmering - Wechsel complex in the Eastern Alps (Austria) belonging to the Lower Austro-Alpine. The carbonatic hard rocks show a distinctive fracture network with only a slight corrosive enlargement of the fractures. The fracture network of the dolo-/limestones can be recorded and characterized at exposures on the surface, where the formation strikes out. The test site is situated within an infrastructural pilot tunnel gallery having two niches with pumping wells at tunnel station 2340 m and 3240 m, pumping since August 1997 and June 1998, respectively. Additionally several observation wells exist at distances between approximately 100 meters to over 1 km to the pumping wells. The data base consists of long term monitoring data, daily water level measurements from 1997 to 2008. Additionally four data loggers were installed in observation wells at tunnel stations 2485m, 2785m, 3400m, and 3500m measuring the piezometric head and the water temperature at intervals of 15 minutes since summer 2008. In a first step the hydraulic properties were calculated from transient pumping test data using the analytic solution by Theis 1935 and Cooper Jacob 1946 for a rough estimation of the hydraulic properties. For these analyses time periods were selected in which only the first pumping niche was operating. The transmissivities calculated at several observation wells with various distances range from 3.7E-03 m²/s to 7.8E-03 m²/s. With an aquifer thickness of 150 m, hydraulic conductivities range from 2.5E-05 m/s to 5.2E-05 m/s are obtained. Considering that the aquifer includes both fracture and matrix porosity, the analytical solution by Moench 1984 was also used to evaluate the pumping test data, yielding slightly lower transmissivities from 3.2E-03 m²/s to 5.7E-03 m²/s. In a next step, hydraulic pulses through the aquifer stimulated by varying the pumping rates will be monitored and interpreted in terms of hydraulic aquifer properties. The outcome of these analyses will be compared to the earlier results of packer tests within the same tectonic and lithological formation. At a later stage it is planned that the results will be integrated into a numerical model to evaluate the superposition of the two pumping niches and the relationship between recharge processes and the variability of the flow. Additionally, it will be possible to assess the scale dependency of hydraulic properties in this type of carbonatic formation.

Masser, E.; Winkler, G.; Birk, S.

2009-04-01

377

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

NASA Astrophysics Data System (ADS)

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

Lipovsky, B.; Dunham, E. M.

2013-12-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

379

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

380

Comparison of conventional radiography with cone beam computed tomography for detection of vertical root fractures: an in vitro study.  

PubMed

To assess the diagnostic accuracy of cone beam computed tomography (CBCT) in comparison with conventional radiography for vertical root fractures, 50 of 100 teeth were subjected to vertical root fracture (VRF) and then placed in dry mandibles. 3D scans were obtained for all teeth, and conventional radiographs were used as control images. All the images were assessed by 6 observers, who determined the presence of root fractures by using a 5-point confidence rating scale. The mean area under the curve (Az) for CBCT was 0.91, and that for conventional radiography was 0.64. The difference between the modalities was statistically significant (P = 0.003). On the basis of interclass coefficient, inter-observer agreement for CBCT was 0/750, and that for conventional radiography was 0/637. Thus CBCT was shown to be significantly better than conventional periapical radiography for diagnosis of vertical root fractures in vitro. PMID:21206162

Varshosaz, Masoud; Tavakoli, Mohammad A; Mostafavi, Maryam; Baghban, Alireza A

2010-12-01

381

Fracture characterization of multilayered reservoirs  

SciTech Connect

Fracture treatment optimization techniques have been developed using Long-Spaced-Digital-Sonic (LSDS) log, pumpin-flowback, mini-frac, and downhole treating pressure data. These analysis techniques have been successfully applied in massive hydraulic fracturing (MHF) of ''tight gas'' wells. Massive hydraulic fracture stimulations have been used to make many tight gas reservoirs commercially attractive. However, studies have shown that short highly conductive fractures are optimum for the successful stimulation of wells in moderate permeability reservoirs. As a result, the ability to design and place optimal fractures in these reservoirs is critical. This paper illustrates the application of fracture analysis techniques to a moderate permeability multi-layered reservoir. These techniques were used to identify large zonal variations in rock properties and pore pressure which result from the complex geology. The inclusion of geologic factors in fracture treatment design allowed the placement of short highly conductive fractures which were used to improve injectivity and vertical sweep, and therefore, ultimate recovery.

Britt, L.K.; Larsen, M.J.

1986-01-01

382

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

EPA Science Inventory

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

383

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

E-print Network

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

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

2012-01-01

384

Estimation of upscaled hydraulic conductivity profiles along a borehole in low permeability crystalline rock using discrete fracture network models  

NASA Astrophysics Data System (ADS)

In Japan, the Mizunami Underground Research Laboratory (MIU) project is being run by the Japan Atomic Energy Agency to establish comprehensive techniques for investigation, analysis and assessment of the deep geological environment with different spatial scales in fractured crystalline rock. The project is implemented in three overlapping phases: Surface-based investigation (Phase I), Construction of shafts and galleries (Phase II) and Operation of research galleries (Phase III). In this study, the following issues are considered to achieve the above-mentioned goals of the project and to establish methodologies of investigation, modeling and interpretation for evaluating the groundwater flow characteristics efficiently: - to newly develop the groundwater flow modeling methodologies considering the hydraulic heterogeneity due to the water-conducting features (WCFs) in the fractured rock - to establish the methodologies to refine the groundwater flow model based on the information in the phased approach of the project (Phase I to III) The modeling and analysis considers hydraulic heterogeneity on the block scale (block dimension in the order of several tens of meters). The data from the deep borehole investigations during the Phase I have been applied for upscaling of transmissivity profiles into equivalent hydraulic conductivities. Profiles of the equivalent hydraulic conductivity can be applied to groundwater flow models based on an equivalent porous medium approach that are used for hydrogeological characterization at over the several kilometers scale. A combined interpretation of core observations, BTV (Borehole Television) and fluid logging has been used to identify and to classify WCFs among observed fractures in three deep boreholes. Transmissivity profiles of WCFs were determined by the interpretation of fluid logging and the results of short interval packer tests. An equivalent hydraulic conductivity for the sub-divided block is calculated using a hydraulic discrete fracture network (hydroDFN) model based on the information. Long interval packer test results have been used to evaluate uncertainty in the calculated equivalent hydraulic conductivity. Groundwater flow analyses using developed hydroDFN model are also carried out to assess groundwater flow conditions around galleries.

Hashimoto, S.; Saegusa, H.; Tanaka, T.; Ando, K.; Bruines, P.

2008-12-01

385

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

386

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

387

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

388

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

PubMed

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

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

2014-08-19

389

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

PubMed

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

Burleson, Elizabeth

2012-01-01

390

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

PubMed

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

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

2014-06-30

391

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

PubMed

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

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

2014-02-18

392

A simplified approach to design of fracturing treatments using high viscosity cross-linked fluids  

SciTech Connect

Simple models are presented to evaluate or design hydraulic fracturing treatments using perfect transport fluids. The fracture geometry program calculates dimensions of a vertically contained fracture and the expected productivity ratio for the fractured well. A sand concentration program helps schedule sand to prevent sandouts and to ensure sufficient proppant at the wellbore.

McLeod, H.O.

1983-03-01

393

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

PubMed

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

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

2014-06-01

394

Evaluation of the irreversible dimensions of radial-circular cracks opened in rock subjected to hydraulic fracturing  

SciTech Connect

The authors propose a method to determine the parameters of radial-circular cracks on the basis of analysis of the interaction between a viscoelastic fluid and an elastobrittle rock under impulse-injection conditions. They examine the horizontal fracture of rock at a depth characteristic for geotechnological wells, where the effect of structural nonuniformities of the rock is insignificant, owing to the presence of a field of compressive stresses, and an initial crack of the required dimensions which initiates the failure is created by familiar technical methods. The viscous flow of fluid in the crack is a basic factor that slows crack development in the absence of vigorous seepage of fluid. In the case of hydraulic fracturing with a fluid having a high viscosity with other conditions equal, the authors expect that the radius of the crack will be smaller than that during fracturing with a low-viscosity fluid.

Vouk, A.A.; Beloivan, A.F.; Mikhalyuk, A.V.; Voitenko, Y.I.

1986-02-01

395

Analysis and Numerical Modeling of Hydraulic Fracturing During Cyclic Steam Stimulation in Oil Sands  

Microsoft Academic Search

Cyclic steam stimulation in oil sands above fracturing pressure is analyzed by numerical modeling. A numerical model is formulated that simultaneously describes the fracturing process and reservoir behavior for different types of fracture geometry. The model is used to study the differences in performance expected for different fracture types. The comparison of model results with the data from a first-cycle

A. Settari; J. M. Raisbeck

1981-01-01

396

A new iterative scheme to determine reservoir and fracture properties using early time test data for hydraulically fractured wells  

E-print Network

conductivity which is invalid The citation on the following pages follows the style of the Journal f Oet ole f~holo in most of the practical cases. Cinco, et al. developed type curves for finite conductivity fractures. This method requires matching... length after the convergence of permeability, two successive fracture length values did not differ by more than ten percent. Obviously, buildup that reflected wellbore storage and fracture and formation damage had to be screened. A specific example...

Rahim, Zillur

2012-06-07

397

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

USGS Publications Warehouse

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

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

1998-01-01

398

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

399

A follow-up study on extracorporeal fixation of condylar fractures using vertical ramus osteotomy  

PubMed Central

Objectives The aim of this study is to report the results of extracorporeal fixation in patients with mandibular condylar fractures and compare them with the clinical results of conservative treatment. Materials and Methods The medical records of 92 patients (73 male [M] : 19 female [F], age 13-69 years, mean 33.1 years) treated for condylar fractures at the Department of Oral and Maxillofacial Surgery in Sun Dental Hospital (Daejeon, Korea) from 2007 to 2012 were reviewed. Patients were divided into three groups: group A (23 patients; M : F=18 : 5, age 21-69 years, mean 32.6 years), treated with extracorporeal fixation; group B (30 patients; M : F=24 : 6, age 16-57 years, mean 21.1 years), treated by conventional open reduction; and group C (39 patients; M : F=31 : 8, age 16-63 years, mean 34.4 years), treated with the conservative method ('closed' reduction). Clinical and radiographic findings were evaluated and analyzed statistically. Results Occurrence of postoperative condylar resorption correlated with certain locations and types of fracture. In this study, patients in group A (treated with extracorporeal fixation) did not demonstrate significant postoperative complications such as malocclusion, mandibular hypomobility, temporomandibular disorder, or complete resorption of condyle fragments. Conclusion In superiorly located mandibular condyle fractures, exact reconstruction of condylar structure with the conventional open reduction technique can be difficult due to the limited surgical and visual fields. In such cases, extracorporeal fixation of the condyle using vertical ramus osteotomy may be a better choice of treatment because it results in anatomically accurate reconstruction and low risk of complications. PMID:24868504

Park, Sung Yong; Im, Jae Hyoung; Yoon, Seong Hoe

2014-01-01

400

Active monitoring of hydraulic and mechanical properties variations during the hydraulic stimulation of a fractured porous reservoir: Some preliminary results from the HPPP Project  

NASA Astrophysics Data System (ADS)

A new protocol of active geophysical monitoring is used to investigate the downhole changes in the hydromechanical response of a naturally porous reservoir layer with 80° dipping fractures where permeability was artificially enhanced by a hydraulic jacking test conducted by a step-wise increase of the fluid pressure. The protocol, called the High-Pulse Poroelasticity Protocol (HPPP) (http://hppp.unice.fr/), is focusing on controlled-impulsive source repeated observations and interpretation of rock properties changes over the seismic band of frequencies. The excitation source corresponds to a fast hydraulic pulse imposed in a small section of a borehole. The source is monitored with a special borehole probe based on fiber-optic sensors which allow dynamic fluid pressure/3D-mechanical deformation measurements, with reflection of light at specific wavelength from Fabry-Pérot or fiber Bragg gratings mounted between inflatable packers. Within the injection zone, fluid pressure and deformation waves of 1 to 500 Hz and static hydraulic diffusion are simultaneously measured to quantify the hydromechanical couplings Two identical pressure pulses were performed to test the rock three-dimensionnal mechanical response before and after the jacking test. It clearly appears that (1) the magnitude of the rock deformation is a factor of 3 higher, and (2) the principal deformation component pitch is rotated of about 20° with more radial deformation of the layer after the jacking test. Those preliminary tests show that the HPPP protocol can actively improve downhole monitoring of both hydraulic and mechanical bulk properties changes of rocks under strong dynamic stress-flow couplings.

Cappa, F.; Guglielmi, Y.

2010-12-01

401

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

USGS Publications Warehouse

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

Paillet, Fredrick L.; Olson, James D.

1994-01-01

402

Comparison of Water Use for Hydraulic Fracturing for Unconventional Oil and Gas versus Conventional Oil.  

PubMed

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

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

2014-10-21

403

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

PubMed Central

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

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

2014-01-01

404

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

PubMed

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

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

2014-01-01

405

Sensitivity of time lapse seismic data to the compliance of hydraulic fractures  

E-print Network

We study the sensitivity of seismic waves to changes in the fracture normal and tangential compliances by analyzing the fracture sensitivity wave equation, which is derived by differentiating the elastic wave equation with ...

Fang, Xinding

2013-01-01

406

A numerical study on the correlation between fracture transmissivity, hydraulic aperture and transport aperture  

Microsoft Academic Search

Quantitative evaluation of the groundwater velocity in the fractures is a key part of contaminants transport assessment especially in the radioactive waste disposal programs. In a hydrogeological model such as the discrete fracture network model, the transport aperture of water conducting fracture is one of the important parameters for evaluating groundwater velocity. Tracer tests that measure velocity (or transport aperture)

A. Sawada; A. Takebe; K. Sakamoto

2006-01-01

407

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

E-print Network

colloid and artificial microsphere transport in natural discrete fractures Ori Zvikelsky a,b , Noam Available online 22 April 2008 Keywords: Fractures Colloidal transport Microspheres Clay Montmorillonite.34-m montmorillonite particles, Li+ and Br- was investigated in a naturally fractured chalk core

408

Hydraulic well testing inversion for modeling fluid flow in fractured rocks using simulated annealing: a case study at Raymond field site, California  

NASA Astrophysics Data System (ADS)

Cluster variable aperture (CVA) simulated annealing (SA) is an inversion technique to construct fluid flow models in fractured rocks based on the transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes element apertures for a cluster of fracture elements in order to improve the match to observed pressure transients. This inversion technique has been applied to hydraulic data collected at the Raymond field site, CA to examine the spatial characteristics of the flow properties in a fractured rock mass. Two major conductive zones have been detected by various geophysical logs, geophysical imaging techniques and hydraulic tests; one occurring near a depth of 30 m and the other near a depth of 60 m. Our inversion results show that the practical range of spatial correlation for transmissivity distribution is estimated to be approximately 5 m in the upper zone and less than 2.5 m in the lower zones. From the televiewer and other fracture imaging logs it was surmised that the lower conductive zone is associated with an anomalous single open fracture as compared to the upper zone, which is an extensive fracture zone. This would explain the difference in the estimated practical range of the spatial correlation for transmissivity.

Nakao, Shinsuke; Najita, Julie; Karasaki, Kenzi

2000-10-01

409

Determining sources of elevated salinity in pre-hydraulic fracturing water quality data using a multivariate discriminant analysis model  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing has the potential to introduce saline water into the environment due to migration of deep formation water to shallow aquifers and/or discharge of flowback water to the environment during transport and disposal. It is challenging to definitively identify whether elevated salinity is associated with hydraulic fracturing, in part, due to the real possibility of other anthropogenic sources of salinity in the human-impacted watersheds in which drilling is taking place and some formation water present naturally in shallow groundwater aquifers. We combined new and published chemistry data for private drinking water wells sampled across five southern New York (NY) counties overlying the Marcellus Shale (Broome, Chemung, Chenango, Steuben, and Tioga). Measurements include Cl, Na, Br, I, Ca, Mg, Ba, SO4, and Sr. We compared this baseline groundwater quality data in NY, now under a moratorium on hydraulic fracturing, with published chemistry data for 6 different potential sources of elevated salinity in shallow groundwater, including Appalachian Basin formation water, road salt runoff, septic effluent, landfill leachate, animal waste, and water softeners. A multivariate random number generator was used to create a synthetic, low salinity (< 20 mg/L Cl) groundwater data set (n=1000) based on the statistical properties of the observed low salinity groundwater. The synthetic, low salinity groundwater was then artificially mixed with variable proportions of different potential sources of salinity to explore chemical differences between groundwater impacted by formation water, road salt runoff, septic effluent, landfill leachate, animal waste, and water softeners. We then trained a multivariate, discriminant analysis model on the resulting data set to classify observed high salinity groundwater (> 20 mg/L Cl) as being affected by formation water, road salt, septic effluent, landfill leachate, animal waste, or water softeners. Single elements or pairs of elements (e.g. Cl and Br) were not effective at discriminating between sources of salinity, indicating multivariate methods are needed. The discriminant analysis model classified most accurately samples affected by formation water and landfill leachate, whereas those contaminated by road salt, animal waste, and water softeners were more likely to be discriminated as contaminated by a different source. Using this approach, no shallow groundwater samples from NY appear to be affected by formation water, suggesting the source of salinity pre-hydraulic fracturing is primarily a combination of road salt, septic effluent, landfill leachate, and animal waste.

Lautz, L. K.; Hoke, G. D.; Lu, Z.; Siegel, D. I.

2013-12-01

410

Use of arsenic and REE in black shales as potential environmental tracers in hydraulic fracturing operations  

NASA Astrophysics Data System (ADS)

Black shales commonly targeted for shale gas development were deposited under low oxygen concentrations, and typically contain high As levels. The depositional environment governs its solid-phase association in the sediment, which in turn will influence degree of remobilization during hydraulic fracturing. Organic carbon (OC), trace element (TE) and REE distributions have been used as tracers for assessing deep water redox conditions at the time of deposition in the Midcontinent Sea of North America (Algeo and Heckel, 2008), during large-scale oceanic anoxic events (e.g., Bunte, 2009) and in modern OC-rich sediments underlying coastal upwelling areas (e.g., Brumsack, 2006). We will present REE and As data from a collection of six different locations in the continental US (Kansas, Iowa, Oklahoma, Kentucky, North Dakota and Pennsylvania), ranging in age from Devonian to Upper Pennsylvanian, and from a Cretaceous black shale drilled on the Demerara Rise during ODP Leg 207. We interpret our data in light of the depositional framework previously developed for these locations based on OC and TE patterns, to document the mechanisms leading to REE and As accumulation, and explore their potential use as environmental proxies and their diagenetic remobilization during burial, as part of our future goal to develop a predictive evaluation of arsenic release from shales and transport with flowback waters. Total REE abundance (?REE) ranged from 35 to 420 ppm in an organic rich sample from Stark shale, KS. PAAS-normalized REE concentrations ranged from 0.5 to 7, with the highest enrichments observed in the MREE (Sm to Ho). Neither the ?REE nor the MREE enrichments correlated with OC concentrations or postulated depositional redox conditions, suggesting a principal association with aluminosilicates and selective REE fractionation during diagenesis. In the anoxic reducing environments in which black shales were deposited, sulfide minerals such as FeS2 trap aqueous arsenic in the crystal lattice, but As is also known to bind to the charged surfaces of clay minerals. Our arsenic concentration data show that the highest abundances (up to 70 ppm) are found in sediments with the highest total sulfur concentration (to 2.6 ppm), but there was no clear correlation with organic carbon or aluminosilicate content. We compare our results with preliminary data from a series of flowback waters sampled from ten producing wells in Pennsylvania and from high-pressure high-temperature experimental leaching of Marcellus shale samples.

Yang, J.; Torres, M. E.; Haley, B. A.; McKay, J. L.; Algeo, T. J.; Hakala, A.; Joseph, C.; Edenborn, H. M.

2013-12-01

411

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

412

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

Microsoft Academic Search

Fracture network connectivity is a spatially variable property that is difficult to quantify from standard hydrogeological\\u000a datasets. This critical property is related to the distributions of fracture density, orientation, dimensions, intersections,\\u000a apertures and roughness. These features that determine the inherent connectivity of a fracture network can be modified by\\u000a secondary processes including weathering, uplift and unloading and other mechanisms that

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

413

Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Annual report, September 28, 1995--September 27, 1996  

SciTech Connect

The digital fan margin in the northeast portion of the Yowlumne field contains significant reserves but is not economic to develop using verticle 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 verticle wells while maintaining verticle communication between thin interbedded layers and the wellbore. The equivalent production rate and reserves of three verticle wells are anticipated at one-half to two-thirds the cost.

Niemeyer, B.L.

1997-09-01

414

Numerical analysis of hydraulic characteristics of fracture intersected with karst conduit based on navier-stokes equation  

NASA Astrophysics Data System (ADS)

The flow in karstic geometry is an important problem in groundwater researches and engineering applications. However, the mechanism controlling the flow status in these areas is still not clear. In this study, we investigated the hydraulic characteristics with numerical models considering a single fracture intersected with a karst conduit. The numerical model used here is a FVM model based on Navier-Stokes equation which was successfully verified with the test result taken from literature. Five factors and four levels were considered in this study, including the length of the karst conduit, aperture of the fracture, diameter of the conduit, hydraulic condition and the cross angle and sixteen cases were designed according to orthogonal design. A non-dimensional number ? (the ratio of the fracture aperture to diameter of the conduit) was defined in analysis of the combined effect of the two factors on flow characters. The most important impacting factors and the stability levels were obtained in order to improve the accuracy of the results in numerical simulations. A mathematical model was built for the relationship between discharge of the conduit and the impacting factors with consideration of the combined effects based on dimension analysis and changeable structure genetic algorithm. The converting permeability coefficient was estimated in order to solve the stream wise head loss considering the combined effects of the flow in karst conduit and fractures with Darcy's law. The results show that the most important impacting factor for flux might be the fracture aperture or the diameter of the conduit which is determined by the non-dimensional number ?. The conduit has more influence on the whole pressure field with larger diameter and smaller length. The head loss has a non-linear relationship with the velocity because of the local head loss near the karst conduit. Thus, the local cubic's law is no longer applicable to characterize the flow in the fracture near the conduit. In this situation, the flow can be simulated by the general Darcy's law form with the converting permeability coefficient.

Tao, X.; Zhao, J.; Zhao, Z.; Li, Y.; Qiu, L.

2013-12-01

415

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

E-print Network

perméabilité #12;2 2006 GeoX Conference. 1. Introduction The growth of a fracture in rocks under the driving involve the extraction of heat in geothermal reservoirs or induced caving in the mining industry. Usually effect on the fracturing pattern. Discrete simulations using elastic spring networks with disorder

416

Hydraulic Fracture Optimization with a Pseudo-3D Model in Multi-layered Lithology  

E-print Network

based on the so-called two-dimensional models (2D) focus on the optimization of fracture length and width, assuming one can estimate a value for fracture height, while so-called pseudo three dimensional (p-3D) models suitable for multi-layered reservoirs...

Yang, Mei

2011-10-21

417

Unsaturated Hydraulic Conductivity of Fracture and Capillary Networks via Lattice Boltzmann Methods  

Microsoft Academic Search

Modeling flow pathways and deriving constitutive relationships for unsaturated fracture and capillary networks present a challenge due to the multitude of potential invasion patterns and configurations assumed by liquid\\/vapor interfaces, especially at intersections of pores or fractures of unequal size. The multiphase Lattice Boltzmann Method (LBM) offers a promising tool for the computation of interface configurations and movement in such

M. C. Sukop; D. Or

2002-01-01

418

The Multi-Porosity Multi-Permeability and Electrokinetic Natures of Shales and Their Effects in Hydraulic Fracturing of Unconventional Shale Reservoirs  

NASA Astrophysics Data System (ADS)

Imaging studies of unconventional shale reservoir rocks have recently revealed the multi-porosity multi-permeability nature of these intricate formations. In particular, the porosity spectrum of shale reservoir rocks often comprises of the nano-porosity in the organic matters, the inter-particle micro-porosity, and the macroscopic porosity of the natural fracture network. Shale is also well-known for its chemically active behaviors, especially shrinking and swelling when exposed to aqueous solutions, as the results of pore fluid exchange with external environment due to the difference in electro-chemical potentials. In this work, the effects of natural fractures and electrokinetic nature of shale on the formation responses during hydraulic fracturing are examined using the dual-poro-chemo-electro-elasticity approach which is a generalization of the classical Biot's poroelastic formulation. The analyses show that the presence of natural fractures can substantially increase the leak-off rate of fracturing fluid into the formation and create a larger region of high pore pressure near the fracture face as shown in Fig.1a. Due to the additional fluid invasion, the naturally fractured shale swells up more and the fracture aperture closes faster compared to an intrinsically low permeability non-fractured shale formation as shown in Fig.1b. Since naturally fractured zones are commonly targeted as pay zones, it is important to account for the faster fracture closing rate in fractured shales in hydraulic fracturing design. Our results also show that the presence of negative fixed charges on the surface of clay minerals creates an osmotic pressure at the interface of the shale and the external fluid as shown in Fig.1c. This additional Donnan-induced pore pressure can result in significant tensile effective stresses and tensile damage in the shale as shown in Fig.1d. The induced tensile damage can exacerbate the problem of proppant embedment resulting in more fracture closure and reduction of fracture length and productivity. The results also suggest that a fracturing fluid with appropriately designed salinity can minimize the chemically induced tensile damage and, thus, maximize the productivity from the created hydraulic fractures.

Liu, C.; Hoang, S. K.; Tran, M. H.; Abousleiman, Y. N.

2013-12-01

419

Water quality impacts of hydraulic-fracturing chemicals observed in a permeable, quartz-sand aquifer  

NASA Astrophysics Data System (ADS)

A pilot scale experiment was conducted on western Cape Cod, Massachusetts to test the use of hydraulic fracturing (HF) for emplacing permeable reactive barriers (PRB) where the water table is too far below land surface to use standard excavation methods. Two PRB were emplaced 24 to 36 meters below land surface in a plume with low concentrations of perchloroethylene in oxic, mildly acidic groundwater with low concentrations of dissolved salts. The granular aquifer sediments consist of permeable sands and gravels. Quartz comprises greater than 90% by weight of the aquifer sediments but chemical reactivity of the sediments is controlled by micrometer-scale chlorite and illite and nanometer-scale aluminum-substituted goethite. HF fluids contained guar gum (gelling agent), cellulose enzyme and acetic acid (breakers), sodium borate (cross-linker), potassium (K) carbonate (pH adjustor), and sodium (Na) chloride (tracer). Water-quality impacts within about 20 meters of the PRB were monitored over a 1.7-year period following HF. Arrival of HF-chemicals was marked by an increase in boron (B) from ambient concentrations of 6 uM to >800 uM. B concentrations rose for approximately 50 days, much longer than the 22-day period over which HF was conducted. B concentrations subsequently decreased but remained 2-3 times above background concentrations for almost one year. Elevated Na and K concentrations in the HF fluids drove sorption (including ion exchange) reactions resulting in transient increases in naturally occurring major, minor, and trace cations up to 20 to 50 times background concentrations. Increases in dissolved organic carbon (DOC) and decreases in dissolved oxygen (DO) concentrations were observed as B concentrations increased. DOC concentration subsequently decreased but remained significantly above background. DO concentrations remained below detection. Dissolved iron (Fe) and manganese (Mn) concentrations increased as DO concentrations decreased below detection and remained elevated 1.7 years after HF. Reactions with Fe in the PRB may have contributed to the observed Fe concentrations but Mn was likely released from the aquifer sediments. Fe and Mn concentrations remained elevated throughout the sampling period. Dissolved arsenic concentrations increased after anaerobic conditions were established from below detection to 0.3-0.5 uM. HF fluids contained only a subset of the chemicals used in typical HF stimulations and aquifer sediments were likely less reactive than aquifer solids at other sites. Despite these differences, several findings have applicability to other sites. B is a potentially useful tracer of intrusion of HF fluids into aquifers, but elevated concentrations may be short-lived. Sorption reactions driven by differences in dissolved salt concentrations between HF fluids and ambient groundwater result in changes in cation concentrations, including barium and strontium. Organic compounds in HF fluids may drive aerobic aquifers anaerobic. Anaerobic conditions may lead to mobilization of naturally occurring contaminants like arsenic, whose reduced forms are more mobile than oxidized forms.

Kent, D. B.; LeBlanc, D. R.; Smith, R. L.

2012-12-01

420

This is the pre-peer reviewed version of the following article: "Can hydraulic fracturing make Poland self-sufficient in natural gas?", which will be published in final form in a  

E-print Network

The International Energy Agency (IEA) has highlighted hydraulic fracturing (fracking) as the key to a "Golden Age in the future. In order to improve energy security in the EU, hydraulic fracturing or "fracking," as it commonly is called, is now stated as a possibility. Fracking is discussed in a "Special Report on Unconventional Gas

Patzek, Tadeusz W.

421

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

422

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

SciTech Connect

The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. This report provides results of the second semi-annual technical progress report that consists of three different topics. In the first topic, laboratory experiments were performed on a Berea core to investigate the changes in rock properties and fluid flow under different stress-state conditions. A comparative study of different stress conditions was also conducted to analyze the effect of the various loading systems. The experimental results show that fracture permeability reduces significantly as the stress increases compared to matrix permeability. The hydrostatic and triaxial stresses have greater impacts on permeability reduction compared to applying stress in the uniaxial stress condition. Fracture flow dominates when the applied stress is less, however, the matrix flow rate increases as applied stress increases and dominates at high stress even if the fracture does not heal completely. In the second topic, the preliminary results of static imbibition experiments are presented as a precursor to image the saturation profiles using X-Ray CT scanner. The static and dynamic imbibition experiments have been done previously (Schechter et al, 2002). The imaging of imbibition experiment is underway to track the saturation profiles using X-ray CT scanner. Hence, no more conclusions are drawn from this study at this time. In the last topic, the modeling of fluid flow through a single fracture incorporating the effect of surface roughness is conducted. Fracture permeability is usually estimated by a cubic law that is based on the theory of hydrodynamics for the laminar flow between flat plates. However, the cubic law is too simple to estimate the fracture permeability correctly, because the surface of real fracture is much more complicated and rougher than the surface of flat plate. Several researchers have shown that the flow characteristics of an actual fracture surface would be quite different due to the effect of tortuosity, impact of surface roughness and contact areas. Nonetheless, to date, these efforts have not converged to form a unified definition on the fracture aperture needed in the cubic law. In this study, therefore, we show that the cubic law could still be used to model small-scale and field-scale data as long as it is modeled effectively, accounting for the effect of surface roughness associated with the fracture surface. The goal of this research is to examine the effect of surface roughness for flow through fractures and to effectively incorporate them into simulations with the aid of geostatistics. Since the research has been supported with experimental results, the consistency of the results enabled us to define a methodology for single fracture simulation. This methodology successfully modeled the slow rate and pressure drop from fractured core experiments, which were earlier not possible through parallel plate approach. Observations suggest that the fracture aperture needs to be distributed to accurately model the experimental results. The effect of friction and tortuosity due to surface roughness needs to be taken into account while modeling.

David S. Schechter

2002-10-30

423

In-situ remediation of naturally occurring radioactive materials with high-permeability hydraulic fracturing  

E-print Network

This thesis addresses the problem of removal of Naturally Occurring Radioactive Materials, NORM, and describes an effective alternative to the current treatment method for their removal. High-pen-meability fracturing, recently established...

Demarchos, Andronikos Stavros

2012-06-07

424

Evidence of Reopened Microfractures in Production Data of Hydraulically Fractured Shale Gas Wells  

E-print Network

Frequently a discrepancy is found between the stimulated shale volume (SSV) estimated from production data and the SSV expected from injected water and proppant volume. One possible explanation is the presence of a fracture network, often termed...

Apiwathanasorn, Sippakorn

2012-10-19

425

Investigation of Efficiency Improvements During CO2 Injection in Hydraulically and Naturally Fractured Reservoirs  

SciTech Connect

The objective of this project was to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO2 flooding in heterogeneous or fracture-dominated reservoirs. This report provided results of the second semi-annual technical progress report that consists of three different topics.

Schechter, David S.; Vance, Harold

2003-03-10