Sample records for vertical hydraulic fracture

  1. Vertical Fracture Containment During Massive Hydraulic Fracturing

    Microsoft Academic Search

    D. E. Cormack; R. L. Fung; S. Vijayakumar

    1983-01-01

    Massive hydraulic fractures are projected to play a major role in the recovery of the tremendous reserves of gas tied up in the tight gas sands of the Deep Basin of N. Alberta and British Columbia. One of the major problems in designing fractures in such formations is the uncertain vertical extent of these fractures: fracture containment. This work presents

  2. Vertical fracture containment during massive hydraulic fracturing

    SciTech Connect

    Cormack, D.E.; Fung, R.L.; Vijayakumar, S.

    1983-01-01

    Massive hydraulic fractures are projected to play a major role in the recovery of the tremendous reserves of gas tied up in the tight gas sands of the Deep Basin of N. Alberta and British Columbia. One of the major problems in designing fractures in such formations is the uncertain vertical extent of these fractures: fracture containment. This work presents a procedure for predicting the vertical extent of fractures in multi-layered formations with varying material properties and tectonic stresses. The numeric procedure uses the finite element technique for the rock deformation calculations and employs special high order, crack-tip elements to improve the accuracy of stress intensity calculations. Furthermore, it makes use of the powerful numeric technique of static condensation to reduce computer memory and computation time. The elastic deformation calculation can be coupled to a fluid flow model to predict dynamic fracture growth.

  3. Hydraulic fracturing method to control vertical fracture heights

    Microsoft Academic Search

    J. L. Fitch; L. Masse; W. L. Medlin; M. A. Biot

    1974-01-01

    A method of hydraulically fracturing a subterranean earth formation to form a vertically disposed fracture is described. More particularly, the method controls the height of the vertically disposed fracture such that the fracture does not extend into formations that are adjacent to the target formation. Hydraulic pressure is applied via a well to the formation to initiate a vertical fracture

  4. Method for controlling the vertical growth of hydraulic fractures

    Microsoft Academic Search

    J. L. Fitch; M. K. Strubhar

    1985-01-01

    A method for controlling the vertical growth of hydraulic fractures in subterranean formations. The fracturing gradients of adjacent formations are determined. The fluid density necessary to inhibit the propagation of a hydraulic fracture from one adjacent formation into the other is determined from the fracturing gradients. A fracturing fluid is prepared having the necessary density for inhibiting such hydraulic fracture

  5. Hydrodynamics of a vertical hydraulic fracture

    SciTech Connect

    Narasimhan, T.N.

    1987-03-24

    We have developed a numerical algorithm, HUBBERT, to simulate the hydrodynamics of a propagating vertical, rectangular fracture in an elastic porous medium. Based on the IFD method, this algorithm assumes fracture geometry to be prescribed. The breakdown and the creation of the incipient fracture is carried out according to the Hubbert-Willis theory. The propagation of the fracture is based on the criterion provided by Griffith, based on energy considerations. The deformation properties of the open fracture are based on simple elasticity solutions. The fracture is assumed to have an elliptical shape to a distance equal to the fracture height, beyond which the shape is assumed to be parallel plate. A consequence of Griffith's criterion is that the fracture must propagate in discrete steps. The parametric studies carried out suggest that for a clear understanding of the hydrodynamics of the hydraulic fracture many hitherto unrecognized parameters must be better understood. Among these parameters one might mention, efficiency, aperture of the newly formed fracture, stiffness of the newly formed fracture, relation between fracture aperture and permeability, and well bore compliance. The results of the studies indicate that the patterns of pressure transients and the magnitudes of fracture length appear to conform to field observations. In particular, the discrete nature of fracture propagation as well as the relevant time scales of interest inferred from the present work seem to be corroborated by seismic monitoring in the field. The results suggest that the estimation of least principal stress can be reliably made either with shut in data or with reinjection data provided that injection rates are very small.

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

    Microsoft Academic Search

    Uhri

    1988-01-01

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

  7. Evaluation of rock/fracture interactions during steam injection through vertical hydraulic fractures

    SciTech Connect

    Kovscek, A.R. [Stanford Univ., CA (United States); Johnston, R.M. [CalResources LLC, Bakersfield, CA (United States); Patzek, T.W. [Univ. of California, Berkeley, CA (United States)

    1997-05-01

    The design, results, and analysis of a steamdrive pilot in the South Belridge diatomite, Kern County, California, are reviewed. Pilot results demonstrate that steam can be injected across a 1,000-ft-tall diatomite column using hydraulically fractured wells and that significant oil is produced in response to steaming. A computationally simple numerical model is proposed and used to analyze reservoir heating and volumetric sweep by steam. Results from the analysis show that hydraulic fractures undergoing steam injection can be dynamic and asymmetrical.

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

    E-print Network

    Razminia, Kambiz; Torres, Delfim F M

    2015-01-01

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

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

    E-print Network

    Rasor, Robert Winston

    1978-01-01

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

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

    E-print Network

    Rasor, Robert Winston

    1978-01-01

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

  11. Simultaneous hydraulic fracturing

    Microsoft Academic Search

    Uhri

    1989-01-01

    A process is described for simultaneous hydraulic fracturing of a hydrocarbonaceous fluid-bearing formation comprising: (a) determining a hydraulic pressure necessary to fracture the formation from at least two wells which penetrate the formation; (b) injecting a hydraulic fracturing fluid into both wells under the determined hydraulic pressure; and (c) applying simultaneously the determined hydraulic pressure to the hydraulic fluid contained

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

    Microsoft Academic Search

    David Wallace Hubble

    2003-01-01

    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

  13. Hydraulic fracture geometry: fracture containment in layered formations

    Microsoft Academic Search

    van Eekelen

    1982-01-01

    One of the main problems in hydraulic fracturing technology is the prediction of fracture height. In particular, the question of what constitutes a barrier to vertical fracture propagation is crucial to the success of field operations. An analysis of hydraulic fracture containment effects has been performed. The main conclusion is that in most cases the fracture will penetrate into the

  14. Hydraulic fracture design optimization

    SciTech Connect

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

    1992-06-01

    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.

  15. Hydraulic fracture design optimization

    SciTech Connect

    Advani, S.H.; Lee, T.S. [Lehigh Univ., Bethlehem, PA (United States)

    1992-05-01

    This research and development investigation, sponsored by U.S. DOE and the oil and gas industry, extends previously developed hydraulic fracture geometry models and applies 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.

  16. Hydraulic fracture design optimization

    SciTech Connect

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

    1992-01-01

    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.

  17. Hydraulic Fracturing Sand

    USGS Multimedia Gallery

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

  18. Similarity and dimensional analysis in the plane problem of the propagation of a vertical hydraulic fracture crack in an elastic medium

    Microsoft Academic Search

    A. Kh. Pergament; D. A. Ul’kin

    2010-01-01

    The problem of the growth of a vertical hydraulic fracture crack in an unbounded elastic medium under the pressure produced by a viscous incompressible fluid is studied qualitatively and by numerical methods. The fluid motion is described in the approximation of lubrication theory. Near the crack tip a fluid-free domain may exist. To find the crack length, Irwin’s fracture criterion

  19. Suspensions in hydraulic fracturing

    SciTech Connect

    Shah, S.N. [Univ. of Oklahoma, Norman, OK (United States)

    1996-12-31

    Suspensions or slurries are widely used in well stimulation and hydraulic fracturing processes to enhance the production of oil and gas from the underground hydrocarbon-bearing formation. The success of these processes depends significantly upon having a thorough understanding of the behavior of suspensions used. Therefore, the characterization of suspensions under realistic conditions, for their rheological and hydraulic properties, is very important. This chapter deals with the state-of-the-art hydraulic fracturing suspension technology. Specifically it deals with various types of suspensions used in well stimulation and fracturing processes, their rheological characterization and hydraulic properties, behavior of suspensions in horizontal wells, review of proppant settling velocity and proppant transport in the fracture, and presently available measurement techniques for suspensions and their merits. Future industry needs for better understanding of the complex behavior of suspensions are also addressed. 74 refs., 21 figs., 1 tab.

  20. What Is Hydraulic Fracturing?

    NSDL National Science Digital Library

    2012-01-01

    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.

  1. The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale 

    E-print Network

    Briggs, Kathryn

    2014-05-05

    proppant experiments were run on samples from both zones. Parameters that were controllable, such as proppant size, concentration and type, were kept consistent between the two zones. In addition to comparing experimental fracture conductivity results...

  2. The Influence of Vertical Location on Hydraulic Fracture Conductivity in the Fayetteville Shale

    E-print Network

    Briggs, Kathryn

    2014-05-05

    proppant experiments were run on samples from both zones. Parameters that were controllable, such as proppant size, concentration and type, were kept consistent between the two zones. In addition to comparing experimental fracture conductivity results...

  3. Hydraulic fracture geometry: fracture containment in layered formations

    SciTech Connect

    van Eekelen, H.A.M.

    1982-06-01

    One of the main problems in hydraulic fracturing technology is the prediction of fracture height. In particular, the question of what constitutes a barrier to vertical fracture propagation is crucial to the success of field operations. An analysis of hydraulic fracture containment effects has been performed. The main conclusion is that in most cases the fracture will penetrate into the layers adjoining the pay zone, the depth of penetration being determined by the differences in stiffness and in horizontal in-situ stress between the pay zone and the adjoining layers. For the case of a stiffness contrast, an estimate of the penetration depth is given. 35 refs.

  4. Hydraulic-fracture propagation in layered rock: experimental studies of fracture containment

    Microsoft Academic Search

    L. W. Teufel; J. A. Clark

    1981-01-01

    Fracture geometry is an important concern in the design of a massive hydraulic fracture treatment for improved natural gas recovery from tight gas sands. Possible prediction of vertical fracture growth and containment in layered rock requires an improved understanding of the parameters which may control fracture growth across layer interfaces. We have conducted laboratory hydraulic fracture experiments and elastic finite

  5. Hydraulic fracture propagation in layered rock: experimental studies of fracture containment

    Microsoft Academic Search

    L. W. Teufel; J. A. Clark

    1981-01-01

    Fracture geometry is an important concern in the design of a massive hydraulic fracture treatment for improved natural gas recovery from tight gas sands. Possible prediction of vertical fracture growth and containment in layered rock requires an improved understanding of the parameters which may control fracture growth across layer interfaces. Laboratory hydraulic fracture experiments and elastic finite element studies have

  6. Hydraulic Fracture Containment in Sand

    Microsoft Academic Search

    Y. Dong

    2010-01-01

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

  7. The Effective Fracture Toughness in Hydraulic Fracturing

    Microsoft Academic Search

    Panos Papanastasiou

    1999-01-01

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

  8. Containment of Massive Hydraulic Fractures

    Microsoft Academic Search

    E. R. Simonson; A. S. Abou-Sayed; R. J. Clifton

    1978-01-01

    Based on two-dimensional analyses of three cases involving the relationship of linear fracture mechanics to the containment of massive hydraulic fractures (MHF), Terra Tek Inc. concluded that the mechanical properties of the pay zone and the barrier formation, as well as the minimum horizontal in situ stresses for these layers, play important roles in the prediction of hydraulic-fracture containment. The

  9. Hydraulic fracturing in a naturally fractured reservoir

    SciTech Connect

    Britt, L.K.; Hager, C.J.; Thompson, J.W.

    1994-12-31

    Hydraulic fracturing of wells in naturally fractured reservoirs can differ dramatically from fracturing wells in conventional isotropic reservoirs. Fluid leakoff is the primary difference. In conventional reservoirs, fluid leakoff is controlled by reservoir matrix and fracture fluid parameters. The fluid leakoff rate in naturally fractured reservoirs is typically excessive and completely dominated by the natural fractures. This paper presents several field examples of a fracture stimulation program performed on the naturally fractured Devonia carbonate of West Texas. Qualitative pressure decline analysis and net treating pressure interpretation techniques were utilized to evaluate the existence of natural fractures in the Devonian Formation. Quantitative techniques were utilized to assess the importance of the natural fractures to the fracturing process. This paper demonstrates that bottomhole pressure monitoring of fracture stimulations has benefits over conducting minifrac treatments in naturally fractured reservoirs. Finally, the results of this evaluation were used to redesign fracture treatments to ensure maximum productivity and minimize costs.

  10. Containment of massive hydraulic fractures

    Microsoft Academic Search

    E. R. Simonson; A. S. Abou-Sayed; R. J. Clifton

    1976-01-01

    Hydraulic fracture containment is discussed from the point of view of linear elastic fracture mechanics. Three cases are analyzed: (a) Effect of different material properties for the pay zone and the barrier formation, (b) Characteristic of fracture propagation into region of varying in situ stress and (c) Effect of hydrostatic pressure gradients on fracture propagation into overlying or underlying barrier

  11. Hydraulic Fracturing in Michigan Integrated Assessment

    E-print Network

    Kamat, Vineet R.

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

  12. Effective hydraulic fracture length and the determination of productivity index

    SciTech Connect

    Malekzadeh, D.; Khan, F.U.; Day, J.J. [Texas Tech Univ., Lubbock, TX (United States)

    1995-12-31

    This paper presents a new technique for analyzing the performance of hydraulically fractured vertical wells in bounded reservoirs. The main objective is to present a new set of practical equations, based on the recently introduced concepts in well testing, for evaluating the effective length of the hydraulic fracture contributing to unrestricted production. It is determined that the performance of a hydraulically fractured vertical well with mechanical skin and fracture half length x{sub f1} can be substituted by the performance of a fractured half-length x{sub f2} with no skin. New equations presented in this paper can be used to determine pseudo skin factor, effective fracture half-length, mechanical skin factor, shape factor, and productivity index of fractured vertical wells. The new equations and guidelines given in this paper can be used to determine the magnitude of formation damage around hydraulically fractured vertical wells and to evaluate the success of the stimulation treatment. An example based on simulated well test data is presented to illustrate the application of the new technique. The problems associated with the use of the finite-conductivity fracture model are discussed and it is recommended that the pressure transient data obtained on fractured vertical wells be analyzed with effective hydraulic fracture length concept, in preference to the finite-conductivity fracture model.

  13. Method for enhancement of sequential hydraulic fracturing using control pulse fracturing

    SciTech Connect

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

    1993-07-20

    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.

  14. Simulation of Hydraulic Fractures and their Interactions with Natural Fractures 

    E-print Network

    Sesetty, Varahanaresh

    2012-10-19

    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...

  15. Laboratory Simulations of Hydraulic Fracturing

    Microsoft Academic Search

    J. M. Papadopoulos; V. M. Narendran; M. P. Cleary

    1983-01-01

    Two novel distinctly different laboratory apparatus have been developed to allow controlled, precise, repeatable and observable experimental simulations of hydraulic fracturing over a broad range of well-determined dominant parameters and practical geometries. One system avoids specimen preparation (by using predetermined interface separation), while the other most efficiently employs castable blocks with proper scaling of fracture toughness to correctly capture crack

  16. Fluid pressure variations during hydraulic fracturing

    Microsoft Academic Search

    N. Conrad; A. A. Daneshy

    1985-01-01

    Fluid pressure inside hydraulic fractures causes their propagation. The potential energy of this fluid provides the energy needed for the creation of fracture surfaces. Theoretical analysis of hydraulic fracturing has shown that fluid pressure needed for fracture extension decreases as the fracture becomes longer. Experimental work on 2-dimensional fractures shows the same trend in laboratory specimens. It also shows that

  17. Enhanced hydraulic fracturing of a shallow subsurface formation

    Microsoft Academic Search

    R. D. Hazlett; D. C. Uhri

    1989-01-01

    This paper describes a method for enhancing the propagation of a vertical hydraulic fracture in an earth formation surrounding a borehole where the original in-situ stresses favor a horizontal fracture comprising: supplying a slug of fracturing fluid containing water, a chemical blowing agent, and a surfactant into the formation at a first depth within the borehole which surfactant and blowing

  18. Measuring hydraulic fracture width behind casing using radioactive proppant

    SciTech Connect

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

    1996-09-01

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

  19. Characterization of the hydraulic properties of fractures in chalk.

    PubMed

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

    2003-01-01

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

  20. Hydraulic fracturing process and compositions

    SciTech Connect

    Constien, V. G.; King, M. T.

    1985-09-17

    Improved fracturing processes are described which use novel aqueous hydraulic fracturing fluids. The fluids comprise: (a) an aqueous medium, and (b) a thickening amount of a thickener composition comprising (i) a water-soluble or water-dispersible interpolymer having pendant hydrophobic groups chemically bonded thereto, (ii) a nonionic surfactant having a hydrophobic group(s) that is capable of associating with the hydrophobic groups on said organic polymer, and (iii) a water-soluble electrolyte. Additionally, the fluids preferably contain a stabilizing amount of a thiosulfate salt. As an example, an interpolymer of acrylamide and dodecyl acrylate was used in combination with a nonionic surfactant (HLB of about 10 to about 14) to thicken a dilute aqueous solution of KCl and sodium thiosulfate; the aqueous solution had excellent properties for use as a high temperature hydraulic fracturing fluid.

  1. Interpretation of a hydraulic fracturing experiment, Monticello, South Carolina

    Microsoft Academic Search

    T. N. Narasimhan; W. A. Palen

    1981-01-01

    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

  2. Locating hydraulically active fracture planes

    SciTech Connect

    Malzahn, Mark; Dreesen, Donald; Fehler, Michael

    1988-01-01

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

  3. Hydraulic fracture propagation in layered formations

    Microsoft Academic Search

    Daneshy

    1976-01-01

    This paper reports theoretical and experimental developments on propagation of hydraulic fractures in layered formations. Experimentally, it is shown that unobstructed fractures propagate with a decreasing fracturing fluid pressure. This general trend is in agreement with theoretical predictions. Obstructions to fracture propagation result in an increase in fluid pressure. Also, it is shown that the relative fracturability of rocks can

  4. Hydraulic fracture propagation in layered rock: experimental studies of fracture containment

    SciTech Connect

    Teufel, L.W.; Clark, J.A.

    1981-01-01

    Fracture geometry is an important concern in the design of a massive hydraulic fracture treatment for improved natural gas recovery from tight gas sands. Possible prediction of vertical fracture growth and containment in layered rock requires an improved understanding of the parameters which may control fracture growth across layer interfaces. Laboratory hydraulic fracture experiments and elastic finite element studies have been conducted which show that at least 2 distinct geologic conditions may inhibit or contain the vertical growth of hydraulic fractures in layered rock: (1) a weak interfacial shear strength of the layers, and (2) a compressional increase in the minimum horizontal stress in the bounding layer. The second condition is more important and more likely to occur at depth. Variations in the horizontal stress can result from differences in elastic properties of individual layers in a layered rock sequence. A compressional increase in the minimum horizontal stress can occur in going from high shear modulus into low shear modulus layers.

  5. Rio Blanco massive hydraulic fracture

    SciTech Connect

    Not Available

    1973-01-01

    The Piceance Basin in Colorado contains an estimated 600 trillion cu ft of natural gas in place. Both the Rulison and Rio Blanco events have been detonated to determine the feasibility of nuclear fracturing to stimulate natural gas production in this basin. A demonstration program to test the relative effectiveness of massive hydraulic fracturing (MHF) to achieve natural gas production stimulation from the same gas reservoir is presented. Details are included on MHF design parameters, including surface and subsurface equipment, pumping requirements, evaluation of fracturing results, and all associated test programs; site characteristics and preparation; proposal for gas utilization program; environmental surveillance and comparative analysis of environmental aspects of MHF and nuclear stimulation; gas delivery estimates; project administration; and costs and scheduling.

  6. Microseismic signatures of hydraulic fracture growth in sediment formations: Observations and modeling

    Microsoft Academic Search

    T. Fischer; S. Hainzl; L. Eisner; S. A. Shapiro; J. Le Calvez

    2008-01-01

    We analyzed a microseismic data set from hydraulic fracture stimulation of the gas field in west Texas. We used an automated wave-picking algorithm and obtained a high-density image of induced microseismic events accompanying the hydraulic fracture growth. The microseismic locations delineated a planar fracture growing predominantly in the horizontal direction; the vertical growth was limited by shale layers. A strongly

  7. Hydraulic fracturing experiments in the Great Northern Coal seam

    SciTech Connect

    Jeffrey, R.G.; Weber, C.R.; Vlahovic, W.; Enever, J.R.

    1994-12-31

    Two field-scale hydraulic fracturing experiments were performed in vertical boreholes on the lease of Munmorah Colliery located south of Newcastle, NSW. The treatments fractured the 3-meter thick, 220-meter deep Great Northern coal seam and were designed to provide a direct comparison between a borate-crosslinked gel and a water treatment. The fracture geometries were mapped during mining of the coal seam. Geologic mapping disclosed a well-defined coal face cleat and systematic full-seam joints perpendicular to bedding and trending NW. The vertical hydraulic fractures extended along the joint and face cleat direction. Evidence that an early slurry stage of fine mesh proppant acted to block off one of two competing parallel fractures was found at one of the mineback sites.

  8. Acoustic Character Of Hydraulic Fractures In Granite

    E-print Network

    Paillet, Frederick I.

    1983-01-01

    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 ...

  9. Hydraulic fracture during epithelial stretching.

    PubMed

    Casares, Laura; Vincent, Romaric; Zalvidea, Dobryna; Campillo, Noelia; Navajas, Daniel; Arroyo, Marino; Trepat, Xavier

    2015-03-01

    The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells' cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics. PMID:25664452

  10. Hydraulic fracturing pressures in permeable surface layers

    Microsoft Academic Search

    Hagoort

    1978-01-01

    A theoretical analysis is presented of hydraulic fracturing pressures in permeable subsurface layers situated in a tectonically relaxed area. The analysis is based on the theory of linear poro-elasticity. Three different fracturing pressures can be distinguished: (1) fracture initiation pressure: the pressure in the borehole needed to part undamaged rock around the borehole; (2) fracture opening\\/closing pressure: the pressure in

  11. Hydraulic-Fracture-Treatment Design Simulation

    Microsoft Academic Search

    Ruma Acharya

    1988-01-01

    Hydraulic fracturing is a technique for simulating wells completed in low-permeability reservoirs. The process involves the pressurization of an isolated perforated section of the wellbore with a viscous fluid until the induced stresses exceed the formation strength, which causes a failure and thus creates the fracture. Proppants are then pumped into the newly created fracture with viscous fracturing fluid as

  12. Laboratory imaging of hydraulic fractures using microseismicity

    Microsoft Academic Search

    Zhengwen Zeng

    2002-01-01

    This dissertation starts with an investigation of the industry's needs for future research and development of hydraulic fracturing (HF) technology. Based on the investigation results of a questionnaire answered by some industrial experts, it was found that reliable hydraulic fracturing diagnostic techniques are in need. Further critical review showed that the microseismic method was one of the most promising techniques

  13. Mechanics and direction of hydraulic fracturing

    Microsoft Academic Search

    Daneshy

    1973-01-01

    Use of the in situ principal stresses greatly simplifies the problems of hydraulic fracturing. For one thing, it reduces the number of stresses to 3, thus simplifying the mathematics. Besides, this choice is in harmony with laboratory observations of fracture propagation perpendicular to the least principal stress. In addition to underground stresses, hydraulic stress is also influenced by the mechanical

  14. Hydraulic Fracturing in Saturated Cohesionless Materials

    Microsoft Academic Search

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

    2007-01-01

    Based on the developed experimental techniques, hydraulic fracturing in particulate materials has been directly observed in the laboratory. As a result, we suggested several mechanisms of hydraulic fracturing in particulate materials and determined relevant scaling relationships (e.g., the interplay between elastic and plastic processes). While the ongoing work is likely to change at least some conclusions, it is important that

  15. A PKN Hydraulic Fracture Model Study and Formation Permeability Determination 

    E-print Network

    Xiang, Jing

    2012-02-14

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

  16. Hydraulic fracture propagation in layered rock: Experimental studies of fracture containment

    SciTech Connect

    Teufel, L.W.; Clark, J.A.

    1984-02-01

    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 elastic finite element studies that show that at least two distinct geologic conditions can inhibit or contain the vertical growth of hydraulic fractures in layered rock: a weak interfacial shear strength of the layers and an increase in the minimum horizontal compressive stress in the bounding layer. The second condition is more important and more likely to occur at depth. Differences in elastic properties within a layered rock mass may be important-not as a containment barrier per se, but in the manner in which variations in elastic properties affect the vertical distribution of the minimum horizontal stress magnitude. These results suggest that improved fracture treatment designs and an assessment of the potential success of stimulations in low-permeability reservoirs can be made by determining the in-situ stress state in the producing interval and bounding formations before stimulation. If the bounding formations have a higher minimum horizontal stress, then one can optimize the fracture treatment and maximize the ratio of productive formation fracture area to volume of fluid pumped by limiting bottomhole pressures to that of the bounding formation.

  17. Acoustic-emission monitoring during hydraulic fracturing

    SciTech Connect

    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

    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.

  18. Qualitative pressure profiling to determine wellbore contacts with hydraulic fractures

    SciTech Connect

    Nelson, D.G.; Economides, M.J.

    1996-12-31

    This work discusses a field-based pressure profiling method which allows direct evaluation of two important indicators of hydraulic fracture treatment quality - the presence of multiple fractures and vertical coverage. Individual or groups of active perforations are systematically hydraulically isolated with a conventional dual packer assembly. Short-term pressure changes are measured with downhole memory pressure gauges and comparisons of the pressure response behavior of the isolated intervals are made. Methodology, field test results, and implications are presented in this paper. Field tests show two types of perforation pressure response. Data can show which perforations are connected to fractures and whether multiple fractures have been created, One response ranges from 0 to 2 psi/minute and the other ranges from 3 to 30 psi/minute. The pressure profile results are compared to, and are consistent with, less direct interpretations from production logs and tiltmeter fracture mapping.

  19. Earthquakes Induced by Hydraulic Fracturing in Poland Township, Ohio

    NASA Astrophysics Data System (ADS)

    Skoumal, R.; Brudzinski, M. R.; Currie, B. S.

    2014-12-01

    Felt seismicity induced by hydraulic fracturing is very rare with only a handful of reported cases worldwide. Using an optimized multi-station cross-correlation template matching routine, 77 earthquakes were identified in Poland Township, Mahoning County, Ohio that were closely related spatially and temporally to active hydraulic fracturing operations. We identified earthquakes as small as M ~1 up to M 3, one of the largest earthquakes induced by hydraulic fracturing in the United States. These events all occurred 4-12 March 2014 and the rate decayed once the Ohio Department of Natural Resources issued a shutdown of hydraulic fracturing at a nearby well on 10 March. Using a locally derived velocity model and double difference relocation, the earthquake epicenters occurred during six stimulation stages along two horizontal well legs that were located ~0.8 km away. Nearly 100 stages in nearby wells at greater distances from the earthquake source region did not coincide with detected seismicity. During the sequence, hypocenters migrated ~600 m along an azimuth of 083 degrees defining a vertically oriented plane of seismicity close to the top of the Precambrian basement. The focal mechanism determined for the M 3 event had a vertically oriented left-lateral fault plane consistent with the earthquake distribution and the regional stress field. The focal mechanism, orientation, and depth of hypocenters were similar to that of the 2011 Youngstown earthquake sequence that occurred ~20 km away, but was correlated with wastewater injection instead of hydraulic fracturing. Considering the relatively large magnitude of these events and the b-value of 0.85, it appears the hydraulic fracturing induced slip along a pre-existing fault/fracture zone optimally oriented in the regional stress field.

  20. Computer simulations of proppant transport in a hydraulic fracture

    SciTech Connect

    Unwin, A.T.; Hammond, P.S.

    1995-12-31

    The equations of motion of a slurry in a narrow slot, such as a hydraulic fracture, are presented and solved numerically to obtain an estimate of the amount of gravity-driven vertical motion of proppant that can occur within a fracture during placement. Two types of gravity-driven motion are studied: settling of heavy proppant particles; and convective proppant transport, which refers to the motion driven by large-scale density differences between regions of different proppant concentration. Computer simulations are performed using realistic parameter values. In particular, the authors compare the vertical motion of proppant in a slurry in which the proppant particles are uniformly distributed across the fracture width (referred to as homogeneous flow) with that in a slurry in which some unspecified, but rapid, process has caused all the proppant to migrate across the fracture width into a close-packed sheet at the fracture center (referred to as sheet flow).

  1. Hydraulic fracture diagnosis using chemical tracers

    SciTech Connect

    Gardien, C.J.; Pope, G.A.; Hill, A.D. [Univ. of Texas, Austin, TX (United States)

    1996-12-31

    In this paper, the use of a single-well tracer test for hydraulic fracture diagnosis is explored. Existing methods for hydraulic fracture diagnosis (e.g. well logging and pressure transient testing) often do not provide accurate or unique solutions, so improved methods are needed. The principle behind the use of tracers for hydraulic fracture diagnosis is the dominance of the fracture on the flow field in a hydraulically fractured reservoir and the strong influence of fracture parameters on the flow field. This will be reflected in the tracer response curves of a single-well tracer test in a fractured well, making the tracer test diagnostic of the fracture and its parameters. Several kinds of tracers (conservative, sorbing, reactive and partitioning) have been tested for their diagnostic value by numerical modeling. The major factors of influence on the tracer response have been identified. These factors are combined in a ratio, the tracer influence ratio, which can be used for the estimation of the product of fracture length and fracture height. The tracer behavior is dispersion dominated, which implies that the tracer dispersivity must be known for the tracer test interpretation, or it could be estimated from another tracer test in the same well or another well in the formation. Extensive sensitivity analyses have indicated that the tracer test is only mildly sensitive to a large number of variables which is beneficial for the purpose of hydraulic fracture diagnosis. A conservative tracer appears to be the best candidate for hydraulic fracture diagnosis using a single-well test since it has the largest diagnostic value when the tracer test is optimized.

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

    SciTech Connect

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

    1985-03-01

    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.

  3. Gas condensate damage in hydraulically fractured wells

    E-print Network

    Adeyeye, Adedeji Ayoola

    2004-09-30

    work has a totally different approach. The effects of reservoir depletion are minimized by introduction of an injector well with fluid composition the same as the original reservoir fluid. It also assumes an infinite conductivity hydraulic fracture...

  4. Hydraulic fracturing accelerates coalbed methane recovery

    SciTech Connect

    Holditch, S.A. (Texas A and M Univ. (US)); Ely, J.W.; Semmelbeck, M.E.; Carter, R.H. (S.A. Holditch and Associates (US)); Hinkel, J.J.; Jeffrey, R.G. Jr. (Dowell Schlumberger (US))

    1990-11-01

    Methane production from deep coal seams that never will be mined requires hydraulic fracturing for faster, optimal recovery. Since this can be a complex process, proper formation evaluation beforehand is essential, according to this paper.

  5. Geomechanical review of hydraulic fracturing technology

    E-print Network

    Arop, Julius Bankong

    2013-01-01

    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 ...

  6. Hydraulic fractur ing--also called hy

    E-print Network

    Goodman, Robert M.

    Hydraulic fractur ing--also called hy drofracking or frack ing--is a process where large volumes) is an aquatic invasive spe cies listed on the USDA's federal noxious weeds list (http:// www.aphis.usda.gov/plant_health

  7. Formation stability after hydraulic fracturing

    Microsoft Academic Search

    Panos Papanastasiou

    1999-01-01

    This paper investigates stress changes resulting from fracturing in a weak formation and estimates the reduced risk of formation failure. The analysis is based on fracture propagation and closure of a plane strain elasto-plastic fracture. It is shown that during fracture propagation the area near the fracture tip undergoes plastic deformation, with the result that the in situ stresses there

  8. Microseismic logging: A new hydraulic fracture diagnostic method

    SciTech Connect

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

    1993-03-01

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

  9. Self-potential observations during hydraulic fracturing

    SciTech Connect

    Moore, Jeffrey R.; Glaser, Steven D.

    2007-09-13

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

  10. Evaluation of hydraulic fracturing by transient pressure analysis methods

    Microsoft Academic Search

    Cinco

    1982-01-01

    A brief description is given of flow models currently used for transient pressure analysis in fractured wells. Four such models are considered: (1) infinite conductivity vertical fracture; (2) uniform flux vertical fracture; (3) uniform plan horizontal fracture; and (4) finite conductivity vertical fracture. Modified versions of these models are presented for the cases of damaged fractures and heterogeneous fractures. Methods

  11. Method of arresting hydraulic fracture propagation

    Microsoft Academic Search

    W. E. Rabaa; R. C. Cole; D. L. Meadows

    1991-01-01

    This patent describes a method of hydraulically fracturing a subterranean formation. It comprises: injecting a first fluid through a well bore into a first formation zone and injecting a second fluid through the well bore into a second formation zone which is adjacent to the first zone, the first and second fluids being injected at pressures sufficient to induce fracturing

  12. Hydraulic Tomography for Detecting Fracture Zone

    Microsoft Academic Search

    Yonghong Hao; Tian-Chyi J. Yeh; J ianwei Xiang; A. Illman; K enichi Ando

    Fracture zones and their connectivity in geologic media are of great importance to ground water resources management as well as ground water contamination prevention and remediation. In this paper, we applied a recently developed hydraulic tomography (HT) technique and an analysis algorithm (sequential successive lin- ear estimator) to synthetic fractured media. The application aims to explore the potential utility of

  13. Acoustic emissions during hydraulic fracturing in granite

    SciTech Connect

    Pearson, C.; Albright, J.N.

    1984-01-01

    Hydraulic stimulation experiments being conducted in low-permeability crystalline rocks, at the Department of Energy's Hot Dry Rock Geothermal Site, Fenton Hill, New Mexico, often produce large numbers of microearthquakes. Typically, the early stages of these experiments are aseismic. The rate of acoustic emissions increases rapidly after a critical volume of water, equal to roughly two-thirds of the total amount previously injected, is exceeded, possibly indicating the onset of fracture extension. With local magnitudes ranging between -1 and -6, these events occurring at 3-km depth are too small to detect using surface seismometers, so we monitor the activity using a downhole triaxial geophone system(s) positioned in well(s) close to the reservoir volume. The system provided enough data in early experiments to locate the events using single station seismometry. Recently it became possible to station a second geophone system in a nearby well, that provides valuable additional constraints on event locations. The second tool was also used to measure relative changes in attenuation by comparing signal frequencies for the same event recorded on the two tools. P-wave attenuation does not vary significantly with the source region of the event, however, S-wave attenuation is quite variable, with Q ranging from 170 to 40. This suggests that the attenuation may be due to open water-filled fractures. We located large numbers of acoustic events during three hydraulic stimulation experiments, two of which occurred in March 1979 and one in December 1980. During the first two, event locations clustered near a single north-by-northwest trending vertical plane. During the third experiment (after an extended period of heat extraction) the same general trend was evident, but the zone was much wider and events seemed to occur on a series of parallel planes indicating a more complex structure within the reservoir.

  14. Laboratory Hydraulic Fracture Characterization Using Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Gutierrez, M.

    2013-05-01

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

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

    SciTech Connect

    Mike L. Laue

    1998-05-29

    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.

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

    SciTech Connect

    Mike L. Laue

    1997-05-08

    This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a propagating turbidite complex through the use of hydraulically-fractured horizontal or high-angle wells. The combination of a horizontal or high-angled well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thininterbedded layers and the well bore.

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

    SciTech Connect

    Laue, M.L.

    1999-11-01

    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.

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

    Microsoft Academic Search

    Mike L. Laue

    2001-01-01

    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

  19. Numerical Investigation of Interaction Between Hydraulic Fractures and Natural Fractures 

    E-print Network

    Xue, Wenxu

    2011-02-22

    .3) where 2 2 2 2 1( , ) [ (arctan arctan ) 4 (1 ) ( ) ( ) ( ) ( ) ] y yf x y y x a x a x a In x a y x a In x a y pi ?= ? ? ?? ? + ? ? + + + + + ....................................... (2.4) Knowing the analytical solution... of Hydraulic Fractures and Natural Fractures ................................ 7 1.4 Research Objectives ..................................................................................... 12 1.5 Sign Convention...

  20. Coupling schemes for modeling hydraulic fracture propagation using the XFEM

    E-print Network

    Peirce, Anthony

    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

  1. A synergistic approach to optimizing hydraulic fracturing

    SciTech Connect

    Kessler, C.; Venditto, J.; McMechan, D.; Edwards, P.

    1994-12-31

    Combining measurement, simulation, and imaging technologies into an integrated program can help operators achieve the best hydraulic fracture treatment possible. Hydrocarbon production can be significantly increased when fractures are extended to the planned length, and fracturing fluid is retained within the zone of interest. Fractures that break out of zone increase the risk of excess water production with the hydrocarbon. Consequently, the ability to select suitable operational parameters for hydraulic fracturing is critical to job success. An evaluation of formation properties and potential barriers to hydraulic fracturing can be made with three-dimensional (3D) simulation to integrate data taken from wireline logs, waveform sonic logs, and microfrac measurements. In-situ stress orientation is determined by use of a downhole extensometer, oriented cores, anelastic strain recovery (ASR) measurements, and borehole imaging logs. Sidewall cores can be taken perpendicular to wellbore walls without distorting the borehole or the core taken; orientation of the cores can be determined with imaging logs run after coring. Natural fractures can be viewed with a downhole video camera lowered into the well on fiberoptic cable. Effectiveness of fracture treatments may be evaluated with various gamma ray logging techniques production logs comparing expected production to actual zonal contribution. Refined procedures that result from after-frac analysis can be used to plain field development for optimal reservoir drainage.

  2. Characterizing hydraulically fractured reservoirs using induced microearthquakes

    SciTech Connect

    Fehler, M.

    1991-01-01

    Hydraulic fracturing is a common method employed to increase the production of oil and gas fields. Recently, there has been increased interest in monitoring the microearthquakes induced by hydraulic fracturing as a means of obtaining data to characterize reservoir changeS induced by the injection. Two types of microearthquakes have been observed during hydraulic fracturing. Tensile events have been observed and modeled as the parting of the surfaces of a fracture. A majority of the events observed have been shear-slip events, where two sides of a fault plane slip parallel to each other but in opposite directions. The locations of the microearthquakes can be analyzed to determine regions where significant seismic energy was released, which presumably are regions where injected fluid penetrated into the rock along pre-existing fractures or zones of weakness. The spatial patterns in the locations can be analyzed to fine regions where events cluster along planes, which are interpreted to be the dominant fluid flow paths. Imaging methods can also be applied to the travel time and waveform data to obtain direct evidence for the locations of the fractures or fracture zones. 27 refs., 2 figs.

  3. Microearthquake analysis for hydraulic fracturing process

    Microsoft Academic Search

    Ying-Ping Li

    1996-01-01

    The hydraulic fracture technique is widely applied in the enhancement of petroleum and natural gas productions and in the\\u000a development of geothermal energy. This technique is also used to create an underground fracture zone system for disposal of\\u000a solid and liquid wastes. This is the most recent development in the application of industrial techniques to environmental\\u000a protection scientific problems. Knowledge

  4. Hydraulic fracture characterization with dispersion measurements of seismic waves

    SciTech Connect

    Groenenboom, J.; Duijndam, A.J.W.; Fokkema, J.T. [Delft Univ. of Technology (Netherlands)

    1995-12-31

    During hydraulic fracturing experiments in our laboratory the opening of hydraulic fractures is monitored with ultrasonic transducers. Transmitted and reflected signals show a distinct and strong dispersive behavior. An experiment with a controlled fracture itself can explain the measured dispersion of compressional waves. The strong impedence contrast magnifies the one-way time delay. The ratio of dimensionless fracture width and impedence ratio determines the response and jump in particle displacement. This is in agreement with the linear slip approximation when the fracture compliance is taken proportional to the fracture width. The product of dimensionless fracture width and impedance ratio acts as the dimensionless fracture density and is very small for hydraulic fractures. The jump in de tractions at the fracture interface can thus be neglected. The dispersion measurement approach can be used to monitor the width of hydraulic fractures and could therefore lead to an increased phenomenological understanding of hydraulic fracture growth.

  5. 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

  6. 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

  7. 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

  8. Role of seepage forces on hydraulic fracturing and failure patterns

    E-print Network

    Paris-Sud XI, Université de

    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

  9. Monitoring hydraulic fracturing with seismic emission volume

    NASA Astrophysics Data System (ADS)

    Niu, F.; Tang, Y.; Chen, H.; TAO, K.; Levander, A.

    2014-12-01

    Recent developments in horizontal drilling and hydraulic fracturing have made it possible to access the reservoirs that are not available for massive production in the past. Hydraulic fracturing is designed to enhance rock permeability and reservoir drainage through the creation of fracture networks. Microseismic monitoring has been proven to be an effective and valuable technology to image hydraulic fracture geometry. Based on data acquisition, seismic monitoring techniques have been divided into two categories: downhole and surface monitoring. Surface monitoring is challenging because of the extremely low signal-to-noise ratio of the raw data. We applied the techniques used in earthquake seismology and developed an integrated monitoring system for mapping hydraulic fractures. The system consists of 20 to 30 state-of-the-art broadband seismographs, which are generally about hundreds times more sensible than regular geophones. We have conducted two experiments in two basins with very different geology and formation mechanism in China. In each case, we observed clear microseismic events, which may correspond to the induced seismicity directly associated with fracturing and the triggered ones at pre-existing faults. However, the magnitude of these events is generally larger than magnitude -1, approximately one to two magnitudes larger than those detected by downhole instruments. Spectrum-frequency analysis of the continuous surface recordings indicated high seismic energy associated with injection stages. The seismic energy can be back-projected to a volume that surrounds each injection stage. Imaging seismic emission volume (SEV) appears to be an effective way to map the stimulated reservior volume, as well as natural fractures.

  10. Hydraulic conductivity of rock fractures

    Microsoft Academic Search

    Robert W. Zimmerman; Gudmundur S. Bodvarsson

    1996-01-01

    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

  11. Linking earthquakes and hydraulic fracturing operations

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-01-01

    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.

  12. Gas condensate damage in hydraulically fractured wells 

    E-print Network

    Adeyeye, Adedeji Ayoola

    2004-09-30

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

  13. A comparison of hydraulic fracture field experiments, including mineback geometry data, with numerical fracture model simulations

    SciTech Connect

    Jeffrey, R.G.; Settari, A.; Smith, N.P.

    1995-12-31

    Hydraulic fracture stimulations, including the fracture geometry data from mineback mapping, for two crosslinked HPG gel treatments and one water treatment performed in vertical wells sited over underground coal mines in Queensland and New South Wales, are analyzed and compared to numerical fracture model predictions. The treating pressure gradients for all three treatments were higher than 1.1 psi per foot although the fractures produced were predominately vertical. The two crosslinked gel treatments produced fractures that were propped to a greater extent in the seam down-dip direction. The treatment using water formed two propped sub-parallel fractures and a small horizontal fracture at the top of the seam. Stress conditions in the rock and coal seams were significantly different at the sites. Laboratory parallel-plate scale-model studies are presented that demonstrate the nature of gravity current movement of dense fluid (both clear and slurry) down-dip in an inclined fracture model. Measured velocities are compared to theoretical calculations and to field measurements of asymmetrically propped fractures exposed by mining.

  14. Development of improved design criteria for hydraulic fracturing operations

    Microsoft Academic Search

    1978-01-01

    This dissertation describes analytical simulations of the structural and fluid responses associated with Hydraulic Fracturing Operations (HFO). The work includes finite element model characterization of the mechanisms for re-orientation of formation in situ stresses, representation of hydraulically induced stress fields, fracture width, fracture containment, and fracture area determinations. The effects of layering conditions, in situ stress variation in geological strata

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

    E-print Network

    Lu, Zhiming

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

  16. Studying Hydraulic Fracturing through Time-variant Seismic Anisotropy 

    E-print Network

    Liu, Qifan

    2013-10-01

    . Studying seismic anisotropy by shear wave splitting can help us better understand the relationship between hydraulic fracturing and fracture systems. Shear wave splitting can be caused by fracturing and also can naturally take place in most sedimentary...

  17. Studying Hydraulic Fracturing through Time-variant Seismic Anisotropy

    E-print Network

    Liu, Qifan

    2013-10-01

    . Studying seismic anisotropy by shear wave splitting can help us better understand the relationship between hydraulic fracturing and fracture systems. Shear wave splitting can be caused by fracturing and also can naturally take place in most sedimentary...

  18. Hydraulic fracturing in granite under geothermal conditions

    USGS Publications Warehouse

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

    1980-01-01

    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.

  19. Micromechanical Aspects of Hydraulic Fracturing Processes

    NASA Astrophysics Data System (ADS)

    Galindo-torres, S. A.; Behraftar, S.; Scheuermann, A.; Li, L.; Williams, D.

    2014-12-01

    A micromechanical model is developed to simulate the hydraulic fracturing process. The model comprises two key components. Firstly, the solid matrix, assumed as a rock mass with pre-fabricated cracks, is represented by an array of bonded particles simulated by the Discrete Element Model (DEM)[1]. The interaction is ruled by the spheropolyhedra method, which was introduced by the authors previously and has been shown to realistically represent many of the features found in fracturing and communition processes. The second component is the fluid, which is modelled by the Lattice Boltzmann Method (LBM). It was recently coupled with the spheropolyhedra by the authors and validated. An advantage of this coupled LBM-DEM model is the control of many of the parameters of the fracturing fluid, such as its viscosity and the injection rate. To the best of the authors' knowledge this is the first application of such a coupled scheme for studying hydraulic fracturing[2]. In this first implementation, results are presented for a two-dimensional situation. Fig. 1 shows one snapshot of the LBM-DEM coupled simulation for the hydraulic fracturing where the elements with broken bonds can be identified and the fracture geometry quantified. The simulation involves a variation of the underground stress, particularly the difference between the two principal components of the stress tensor, to explore the effect on the fracture path. A second study focuses on the fluid viscosity to examine the effect of the time scales of different injection plans on the fracture geometry. The developed tool and the presented results have important implications for future studies of the hydraulic fracturing process and technology. references 1. Galindo-Torres, S.A., et al., Breaking processes in three-dimensional bonded granular materials with general shapes. Computer Physics Communications, 2012. 183(2): p. 266-277. 2. Galindo-Torres, S.A., A coupled Discrete Element Lattice Boltzmann Method for the simulation of fluid-solid interaction with particles of general shapes. Computer Methods in Applied Mechanics and Engineering, 2013. 265(0): p. 107-119.

  20. Vertical variation of vertical hydraulic conductivity in channel sediments

    NASA Astrophysics Data System (ADS)

    Chen, X.; Song, J.; Cheng, C.; Wang, D.; Lackey, S.; Burbach, M.

    2007-12-01

    Vertical hydraulic conductivity (Kv) of streambed is of great importance in the analysis of stream-aquifer interactions. We used two methods to estimate the Kv in three rivers of Nebraska. The first method was in-situ permeameter test in river channels. We investigated streambed vertical hydraulic conductivity (Kv) in two depths, one incumbent to the other, immediately beneath the channel surface. Our results demonstrated that streambed Kv in the upper sediment layer was much higher than that in the sediment just beneath the upper layer at each test location. We speculate that hyporheic processes can result in a larger streambed Kv in the upper part of channel sediments. Specifically, water exchange through upwelling and downwelling zones can lead to bigger pore spaces and a more unconsolidated structure of sediments in the upper layer. The upward movement of gas produced by redox processes can loosen sediments and further enlarge pore spaces in the upper layers. Bio- activity in the upper part of the streambed can also expand pore space and thus increase hydraulic conductivity. In-situ permeameter tests penetrated the sediment to depth as much as 90 cm. We then used Geoprobe direct- push technique to generate electrical conductivity log and collect sequences of sediment cores from larger depths. Permeameter tests were conducted on these cores to determine Kv. Our results suggest that Kv values have a decrease tendency with the depth for sediments in these rivers.

  1. Reactivation of a Propped Hydraulic Fracture

    NASA Astrophysics Data System (ADS)

    Sarvaramini, E.; Garagash, D.

    2014-12-01

    The problem of massive fluid injection into a pre-existing fracture has many applications in petroleum industry including underground liquid waste disposal and waterflooding to increase recovery from a hydrocarbon reservoir. Understanding the conditions leading to the re-activation of pre-existing fractures and ensuing propagation is critical for a successful injection project design, and it may also help to mitigate potential environmental hazards, such as contamination of underground aquifers and induced seismicity. The problem of injection of a low viscosity fluid into a permeable formation can be distinguished from conventional hydraulic fracture by the mechanism of fluid leak-off. In conventional fracturing, high viscosity and cake building properties of injected fluid limit leak-off to a 1-D boundary layer incasing the crack. In the case of injection of low viscosity fluid into a fracture, leak-off and related pore fluid diffusion will take place over wider range of scales, from 1-D to 2 or 3-D. We consider a pre-existing stationary propped hydraulic fracture with constrained height into which a fluid is injected under constant flow rate. Although the net effective stress on the crack is initially compressive, the proppant keeps the crack open. It is worthwhile to note that during injection and related pressurization of a propped crack, the fracture breakdown is to be achieved prior to the fracture re-opening. Therefore, the effect of the change of the propped fracture storage on the pressurization dynamics can be neglected. The objective of this work is to study the transient pressurization and the onset of the propagation for a propped fracture. To the end, we formulate and solve a general problem of injection into a fracture accounting for viscous dissipation (i.e. non-uniform pressure distribution). We quantify how the fracture breakdown condition depends upon the rock and fluid properties, the in-situ stress and the fluid injection rate. We also establish a criterion when the assumption of negligible viscous dissipation is justified. The obtained solution is also transportable to the production well test analysis of a fractured well (Cinco et al., SPE 1978).

  2. Seismic characteristics of tensile fracture growth induced by hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Eaton, D. W. S.; Van der Baan, M.; Boroumand, N.

    2014-12-01

    Hydraulic fracturing is a process of injecting high-pressure slurry into a rockmass to enhance its permeability. Variants of this process are used for unconventional oil and gas development, engineered geothermal systems and block-cave mining; similar processes occur within volcanic systems. Opening of hydraulic fractures is well documented by mineback trials and tiltmeter monitoring and is a physical requirement to accommodate the volume of injected fluid. Numerous microseismic monitoring investigations acquired in the audio-frequency band are interpreted to show a prevalence of shear-dominated failure mechanisms surrounding the tensile fracture. Moreover, the radiated seismic energy in the audio-frequency band appears to be a miniscule fraction (<< 1%) of the net injected energy, i.e., the integral of the product of fluid pressure and injection rate. We use a simple penny-shaped crack model as a predictive framework to describe seismic characteristics of tensile opening during hydraulic fracturing. This model provides a useful scaling relation that links seismic moment to effective fluid pressure within the crack. Based on downhole recordings corrected for attenuation, a significant fraction of observed microseismic events are characterized by S/P amplitude ratio < 5. Despite the relatively small aperture of the monitoring arrays, which precludes both full moment-tensor analysis and definitive identification of nodal planes or axes, this ratio provides a strong indication that observed microseismic source mechanisms have a component of tensile failure. In addition, we find some instances of periodic spectral notches that can be explained by an opening/closing failure mechanism, in which fracture propagation outpaces fluid velocity within the crack. Finally, aseismic growth of tensile fractures may be indicative of a scenario in which injected energy is consumed to create new fracture surfaces. Taken together, our observations and modeling provide evidence that failure mechanisms documented by passive monitoring of hydraulic fractures may contain a significant component of tensile failure, including fracture opening and closing, although creation of extensive new fracture surfaces may be a seismically inefficient process that radiates at sub-audio frequencies.

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

    SciTech Connect

    Mike L. Laue

    1998-02-05

    This project attempts to demonstrate the effectivensss of exploiting thin-layered, low energy deposits at the distal margin of a propagating turbinite complex through u se of hydraulically fractgured horizontal of high-angle wells. TGhe combinaton of a horizontal or high-angle weoo and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore.

  4. Influence of Rock Fabric on Hydraulic Fracture Propagation: Laboratory Study

    NASA Astrophysics Data System (ADS)

    Stanchits, S. A.; Desroches, J.; Burghardt, J.; Surdi, A.; Whitney, N.

    2014-12-01

    Massive hydraulic fracturing is required for commercial gas production from unconventional reservoirs. These reservoirs are often highly fractured and heterogeneous, which may cause significant fracture complexity and also arrest propagation of hydraulic fractures, leading to production decrease. One of the goals of our study was to investigate the influence of rock fabric features on near-wellbore fracture geometry and complexity. We performed a series of laboratory tests on Niobrara outcrop shale blocks with dimensions of 30 x 30 x 36 inches in a true-triaxial loading frame. Acoustic Emission (AE) technique was applied to monitor hydraulic fracture initiation and dynamics of fracture propagation. After the tests, the shape of the created hydraulic fracture was mapped by goniometry technique. To estimate fracture aperture, particles of different sizes were injected with fracturing fluid. In all tests, AE analysis indicated hydraulic fracture initiation prior to breakdown or the maximum of wellbore pressure. In most tests, AE analysis revealed asymmetrical hydraulic fracture shapes. Post-test analysis demonstrated good correspondence of AE results with the actual 3D shape of the fracture surface map. AE analysis confirmed that in some of these tests, the hydraulic fracture approached one face of the block before the maximum wellbore pressure had been reached. We have found that in such cases the propagation of hydraulic fracture in the opposite direction was arrested by the presence of mineralized interfaces. Mapping the distribution of injected particles confirmed the creation of a narrow-width aperture in the vicinity of pre-existing interfaces, restricting fracture conductivity. Based on the results of our study, we concluded that the presence of planes of weakness, such as mineralized natural fractures, can result in the arrest of hydraulic fracture propagation, or in poor fracture geometries with limited aperture, that in turn could lead to high net pressure and low fracture conductivity, restricted proppant delivery, and decreased production.

  5. Rheological characterization of hydraulic fracturing slurries

    SciTech Connect

    Shah, S.N. (Halliburton Services, Duncan, OK (United States). Research and Engineering Dept.)

    1993-05-01

    Few studies have dealt with the flow behavior of concentrated suspensions or slurries prepared with non-Newtonian carrier fluids. Therefore, the purpose of this investigation is to present experimental results obtained by pumping various hydraulic fracturing slurries into a fracture model and gathering data on differential pressure vs. flow rate. Several concentrations of hydroxypropyl guard (HPG), a wide range of proppant concentrations, and three test temperatures were studies. The effects of such variables as polymer gelling-agent concentration, proppant concentration, test temperature, and fracture-flow shear rate on the rheological properties of slurries were investigated. The correlations for predicting the relative slurry viscosity for these HPG fluids are presented. Substantial increases in viscosity of fracturing gels were observed, and results are discussed in light of several affecting variables. Results also are compared with those available for Newtonian and non-Newtonian concentrated suspensions. Applications of these correlations to estimate the hindered particle-settling velocity in the fracture caused by the presence of surrounding particles also is discussed. The correlations presented can easily be included in any currently available 2D or 3D fracture-design simulators; thus, the information can be applied directly to predict fracture geometry and extension.

  6. Description and analysis of cored hydraulic fractures -- Lost Hills field, Kern County, California

    SciTech Connect

    Fast, R.E.; Murer, A.S.; Timmer, R.S. (Mobil E and P U.S. Inc., Bakersfield, CA (United States))

    1994-05-01

    An inclined observation well was drilled in shallow (2,000 ft) Opal-A diatomite. Seven sand-propped hydraulic fractures were cored and recovered. The hydraulic fractures were found within 5[degree] of the azimuth measured with tilt meters and were tilted 15[degree] from vertical, oriented perpendicular to the formation bedding dip. Hydraulic fractures widths ranged from less than one sand grain (40/60 mesh) to 0.4 in. Scanning electron microscopy (SEM) examination of fracture faces showed no damage to the matrix from proppant embedment or compaction, and no evidence of guard residue was detected in the proppant pack or on the formation face. Fractures appear to be considerably longer than modeled. Three closely spaced fractures are interpreted to be branches of a single hydraulic fracture treatment. This paper presents a description of the fractures recovered during coring in Well OO2. Findings related to fracture dimensions and orientations, fracture sources, fracture permeability measurements, and fracture characteristics (proppant embedment, presence of gel residue) are presented. Implications related to field development are discussed.

  7. New groups focus on hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-04-01

    The Scientific Advisory Board of the U.S. Environmental Protection Agency (EPA) has formed a 31-member expert panel to conduct a peer review of the agency's upcoming draft report on the potential effects of hydraulic fracturing on drinking water resources, EPA announced on 24 March. Panel members include experts in a number of areas, including petroleum/natural gas engineering, geology/geophysics, and waste water and drinking water treatment.

  8. Self-potential observations during hydraulic fracturing

    Microsoft Academic Search

    Jeffrey R. Moore; Steven D. Glaser

    2007-01-01

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

  9. Self-potential observations during hydraulic fracturing

    Microsoft Academic Search

    Jeffrey R. Moore; Steven D. Glaser

    2007-01-01

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

  10. Coupled Fracture and Flow in Shale in Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Carey, J. W.; Mori, H.; Viswanathan, H.

    2014-12-01

    Production of hydrocarbon from shale requires creation and maintenance of fracture permeability in an otherwise impermeable shale matrix. In this study, we use a combination of triaxial coreflood experiments and x-ray tomography characterization to investigate the fracture-permeability behavior of Utica shale at in situ reservoir conditions (25-50 oC and 35-120 bars). Initially impermeable shale core was placed between flat anvils (compression) or between split anvils (pure shear) and loaded until failure in the triaxial device. Permeability was monitored continuously during this process. Significant deformation (>1%) was required to generate a transmissive fracture system. Permeability generally peaked at the point of a distinct failure event and then dropped by a factor of 2-6 when the system returned to hydrostatic failure. Permeability was very small in compression experiments (< 1 mD), possibly because of limited fracture connectivity through the anvils. In pure share experiments, shale with bedding planes perpendicular to shear loading developed complex fracture networks with narrow apertures and peak permeability of 30 mD. Shale with bedding planes parallel to shear loading developed simple fractures with large apertures and a peak permeability as high as 1 D. Fracture systems held at static conditions for periods of several hours showed little change in effective permeability at hydrostatic conditions as high as 140 bars. However, permeability of fractured systems was a function of hydrostatic pressure, declining in a pseudo-linear, exponential fashion as pressure increased. We also observed that permeability decreased with increasing fluid flow rate indicating that flow did not follow Darcy's Law, possibly due to non-laminar flow conditions, and conformed to Forscheimer's law. The coupled deformation and flow behavior of Utica shale, particularly the large deformation required to initiate flow, indicates the probable importance of activation of existing fractures in hydraulic fracturing and that these fractures can have adequate permeability for the production of hydrocarbon.

  11. Reply to Davies: Hydraulic fracturing remains a possible mechanism for

    E-print Network

    Jackson, Robert B.

    LETTER Reply to Davies: Hydraulic fracturing remains a possible mechanism for observed methane in aquifers overlying the Marcellus formation but asserts that we prematurely ascribed its cause to hydraulic mechanisms were leaky gas well casings and the possibility that hydraulic fracturing might generate new

  12. Marcellus Shale Drilling and Hydraulic Fracturing; Technicalities and

    E-print Network

    Jiang, Huiqiang

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

  13. Hydraulic fracture closure in a pressure-sensitive elastoplastic medium

    Microsoft Academic Search

    Panos Papanastasiou

    2000-01-01

    This paper examines fracture closure in a Mohr-Coulomb pressure-sensitive dilatant material. The analysis is based on fracture propagation and closure of a plane strain geometry using a fully coupled elastoplastic hydraulic fracturing model. It is shown that the closure pattern of a fracture which has first been propagated is completely different from the closure pattern of a pressurized stationary fracture.

  14. Coupling Hydraulic Fracturing Propagation and Gas Well Performance for Simulation of Production in Unconventional Shale Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Wang, C.; Winterfeld, P. H.; Wu, Y. S.; Wang, Y.; Chen, D.; Yin, C.; Pan, Z.

    2014-12-01

    Hydraulic fracturing combined with horizontal drilling has made it possible to economically produce natural gas from unconventional shale gas reservoirs. An efficient methodology for evaluating hydraulic fracturing operation parameters, such as fluid and proppant properties, injection rates, and wellhead pressure, is essential for the evaluation and efficient design of these processes. Traditional numerical evaluation and optimization approaches are usually based on simulated fracture properties such as the fracture area. In our opinion, a methodology based on simulated production data is better, because production is the goal of hydraulic fracturing and we can calibrate this approach with production data that is already known. This numerical methodology requires a fully-coupled hydraulic fracture propagation and multi-phase flow model. In this paper, we present a general fully-coupled numerical framework to simulate hydraulic fracturing and post-fracture gas well performance. This three-dimensional, multi-phase simulator focuses on: (1) fracture width increase and fracture propagation that occurs as slurry is injected into the fracture, (2) erosion caused by fracture fluids and leakoff, (3) proppant subsidence and flowback, and (4) multi-phase fluid flow through various-scaled anisotropic natural and man-made fractures. Mathematical and numerical details on how to fully couple the fracture propagation and fluid flow parts are discussed. Hydraulic fracturing and production operation parameters, and properties of the reservoir, fluids, and proppants, are taken into account. The well may be horizontal, vertical, or deviated, as well as open-hole or cemented. The simulator is verified based on benchmarks from the literature and we show its application by simulating fracture network (hydraulic and natural fractures) propagation and production data history matching of a field in China. We also conduct a series of real-data modeling studies with different combinations of hydraulic fracturing parameters and present the methodology to design these operations with feedback of simulated production data. The unified model aids in the optimization of hydraulic fracturing design, operations, and production.

  15. Potential contaminant pathways from hydraulically fractured shale to aquifers.

    PubMed

    Myers, Tom

    2012-01-01

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

  16. Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions

    E-print Network

    Peirce, Anthony

    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

  17. On Mechanisms of Hydraulic Fracturing in Cohesionless Materials

    Microsoft Academic Search

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

    2005-01-01

    Based on the developed experimental techniques, hydraulic fracturing in particulate materials has been directly observed in the laboratory. We have conducted an experimental series by varying such controlling parameters as the properties of particulate materials and fracturing fluids, boundary conditions, initial stress states, and injection volumes and rates. As a result, we suggested some (hopefully, fundamental) mechanisms of hydraulic fracturing

  18. Analysis of Natural Hydraulic Fracturing of Shales During Sedimentation

    Microsoft Academic Search

    I. Ozkaya

    1986-01-01

    An approximate mathematical model of the time variation of excess head at the middle of a shale layer during burial is obtained and used in the analysis of natural hydraulic fracturing by excess pore pressure. The fundamental variables that control fracturing are critical stress intensity factor, hydraulic conductivity, specific storage, Poisson's ratio, sedimentation rate, and shale-layer thickness. A simple fracture

  19. A Coupled Fracturing Model and its Application to Hydraulic Fracturing

    Microsoft Academic Search

    J.-C. Roegiers; Y. Ishijima

    1983-01-01

    Although hydraulic fracturing has been used for several decades in the stimulation of hydrocarbon reservoirs, a thorough understanding of the interwoven phenomena is still lacking, especially in the case of porous media. This paper describes a two-dimensional numerical approach allowing the study of the fluid\\/rock skeleton interaction. The elastic stress analysis is coupled with the transient fluid-flow phenomenon. By introducing

  20. Analysis of Hydraulically Fractured Wells With Pressure Buildup Tests

    Microsoft Academic Search

    Lee W. J

    1967-01-01

    Procedures are presented for interpreting pressure buildup tests of fractured reservoirs. Both horizontal and vertical fracture orientations are considered and the procedures are intended to be used for evaluating well fracture treatments. Fractures of finite conductivity are studied. A computerized reservoir model is described which can be used to determine fracture length and fracture conductivity. Assumptions involved in developing the

  1. Formation of Network Fractures During Hydraulic Fracturing of the Barnett Shale, a Tight Gas Shale with Preexisting Fractures

    Microsoft Academic Search

    S. Busetti; Z. Reches

    2007-01-01

    Hydraulic fracturing operations generate new fractures as well as dilate preexisting fractures, creating networks of fractures. Here we model the complexity of the created network fractures and apply the results to wellbore log data and hydrofracture operations in the Barnett Shale, a tight gas-shale that requires artificial fracture stimulation to produce. It is shown that the resulting fracture geometry is

  2. Advanced hydraulic fracturing methods to create in situ reactive barriers

    Microsoft Academic Search

    L. Murdoch; B. Siegrist; T. Meiggs

    1997-01-01

    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

  3. A Study of Hydraulic Fracturing Initiation in Transversely Isotropic Rocks 

    E-print Network

    Serajian, Vahid

    2011-10-21

    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...

  4. A Study of Hydraulic Fracturing Initiation in Transversely Isotropic Rocks

    E-print Network

    Serajian, Vahid

    2011-10-21

    is then used to study the fracture initiation pressure variations with anisotropy. A sensitivity analysis is carried out on the impact of Young's modulus and Poisson's ration, on the fracture initiation pressure. The results are useful in designing hydraulic...

  5. Vertical root fractures and their management

    PubMed Central

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

    2014-01-01

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

  6. Formation interface fracturing experiment: an in situ investigation of hydraulic fracture behavior near a material property interface. Final report

    Microsoft Academic Search

    N. R. Warpinski; D. A. Northrop; R. A. Schmidt; W. C. Vollendorf; S. J. Finley

    1981-01-01

    Two hydraulic fractures were created, one above and one below an ash-fall tuff-welded tuff formation interface. These formations have significant differences in their Young`s moduli, Poisson`s ratios and porosities. Sufficient cement was injected into each zone to create vertical fractures of 600 ft total length if the height was restricted to 50 ft; 256 and 117 bbls were injected at

  7. Calibration of hydraulic and tracer tests in fractured media

    E-print Network

    Politècnica de Catalunya, Universitat

    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

  8. Incorporation of 2D fluid flow into a pseudo-3D hydraulic fracturing simulator

    SciTech Connect

    Weng, X. (Arco E and P Technology, Plano, TX (United States))

    1992-11-01

    Pseudo 3D (P3D) hydraulic fracturing models often overpredict fracture height for a poorly contained fracture. This is caused partly by either the neglect of the fluid flow component in the vertical direction or a crude treatment of the 2D fluid flow in the fracture as 1D flow in the vertical direction in the fracture-height calculation. This paper presents a height-growth model that adopts a flow field more representative of the actual 2D flow in a fracture. In this model, the fracture is divided into two regions: an inner region where the flow direction is nearly horizontal, and an outer region where the flow field is approximated by a radial flow from an imaginary source. The governing equations for determining height growth rate and the numerical method for solving these equations are described.

  9. Seismic monitoring of the growth of a hydraulic fracture zone at Fenton Hill, New Mexico

    SciTech Connect

    Li, Y.; Cheng, C.H.; Toksoez, M.N. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-01-01

    The hydraulic fracturing technique is an important method for enhancing hydrocarbon recovery, geothermal energy extraction, and solid waste disposal. Determination of the geometry and growth process of a hydraulic fracture zone is important for monitoring and assessing subsurface fractures. A relative-source-location approach, based on a waveform correlation and a grid search method, has been developed to estimate relative hypocenter locations for a cluster of 157 microearthquakes induced by hydraulic fracturing at the Los Alamos Hot Dry Rock (HDR) geothermal site. Among the 157 events, 147 microearthquakes occurred in a tight cluster with a dimension of 40 m, roughly defining a vertical hydraulic fracture zone with an orientation of N40{degree}W. The length, height, and width of the hydraulic fracture zone are estimated to be 40, 35, and 5 m, respectively. Analysis of the spatial-temporal pattern of the induced microearthquakes reveals that the fracture zone grew significantly, averaging 0.2m/ minute in a two-hour period toward the northwest along the fracture zone strike.

  10. Analytical Modeling of Shale Hydraulic Fracturing and Gas Production

    NASA Astrophysics Data System (ADS)

    Xu, W.

    2012-12-01

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

  11. Interpretation of hydraulic fracture mapping experiments

    SciTech Connect

    Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States)

    1994-12-31

    Simple mechanical models of the response of a reservoir to hydraulic fracturing have been developed in order to interpret the response of microseismic and downhole-tiltmeter diagnostic systems and determine the important reservoir and treatment parameters that influence the response. For microseisms, results of this study can be used to delineate the width of the seismically active zone and possibly distinguish different types of signals. For downhole tiltmeters, the results can be used to interpret the measured tilt response and provide information on height growth, closure pressure and proppant placement.

  12. 40 CFR 147.52 - State-administered program-Hydraulic Fracturing of Coal Beds.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  13. 78 FR 25267 - Request for Information To Inform Hydraulic Fracturing Research Related to Drinking Water Resources

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-30

    ...FRL-9807-7] Request for Information To Inform Hydraulic Fracturing Research Related to Drinking...research on the potential impacts of hydraulic fracturing on drinking water resources...research to examine the relationship between hydraulic fracturing and drinking water...

  14. 75 FR 35023 - Informational Public Meetings for Hydraulic Fracturing Research Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

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

  15. 77 FR 67361 - Request for Information To Inform Hydraulic Fracturing Research Related to Drinking Water Resources

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ...FRL-9750-8] Request for Information To Inform Hydraulic Fracturing Research Related to Drinking...research on the potential impacts of hydraulic fracturing on drinking water resources...research to examine the relationship between hydraulic fracturing and drinking water...

  16. 78 FR 20637 - Notification of Public Meeting and a Public Teleconference of the Hydraulic Fracturing Research...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-05

    ...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...

  17. 78 FR 55253 - Notification of Public Teleconference of the Hydraulic Fracturing Research Advisory Panel

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-10

    ...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...

  18. Veining Failure and Hydraulic Fracturing in Shales

    NASA Astrophysics Data System (ADS)

    Mighani, S.; Sondergeld, C. H.; Rai, C. S.

    2014-12-01

    During the hydraulic fracturing, the pressurized fluid creates new fractures and reactivates existing natural fractures forming a highly conductive Stimulated Reservoir Volume (SRV) around the borehole. We extend the previous work on Lyons sandstone and pyrophyllite to anisotropic shale from the Wolfcamp formation. We divide the rock anisotropy into two groups: a) conventional and b) unconventional (shaly) anisotropy. X-ray Computed Tomography (CT), compressional velocity anisotropy, and SEM analysis are used to identify three causes of anisotropy: bedding planes, clay lamination, and calcite veins. Calcite vein is a subsequently filled with calcite bonded weakly to the matrix. Velocity anisotropy and visual observations demonstrate the calcite filled veins to be mostly subparallel to the fabric direction. Brazilian tests are carried out to observe the fracture initiation and propagation under tension. High speed photography (frame rate 300,000 frame/sec) was used to capture the failure. Strain gauges and Acoustic Emission (AE) sensors recorded the deformation leading up to and during failure. SEM imaging and surface profilometry were employed to study the post-failure fracture system and failed surface topology. Fracture permeability was measured as a function of effective stress. Brazilian tests on small disks containing a centered single vein revealed the shear strength of the veins. We interpret the strain data and number, frequency, and amplitude of AE events which are correlated well with the observed fracture process zone, surface roughness, and permeability. The unpropped fracture has enhanced permeability by two orders of magnitude. The observed anisotropic tensile failure seems to have a universal trend with a minimum strength occurring at 15o orientation with respect to the loading axis. The veins at 15o orientation with respect to the loading axis were easily activated at 30% of the original failure load. The measured strength of the vein is as low as 6% of the matrix. Surface roughness measurements show the vein to be as rough as the main tensile fracture in the matrix. The observations suggest that fracking through a deviated well reduces the breakdown pressure significantly and can activate a large number of veins with enhanced conductivity without the need for excessive proppant injection.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

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

    SciTech Connect

    Mike L. Laue

    1998-11-06

    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.

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

    PubMed

    Ewers, U; Gordalla, B; Frimmel, F

    2013-11-01

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

  2. Hydraulic Fracture Propagation in the Presence of Planes of Weakness

    Microsoft Academic Search

    Abbas Daneshy

    1974-01-01

    A study is made of hydraulic fracturing of formations containing natural flaws. The 3 factors of importance are shown to be the strength of the weakness plane, its orientation with respect to the least compressive principal stress, and the difference between the principal stress magnitudes. Material flaws with dimensions that are small compared with the induced hydraulic fracture are shown

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  4. Far-field hydraulic fracture geometry: A changing paradigm

    SciTech Connect

    Mahrer, K.D.; Aud, W.W.; Hansen, J.T.

    1996-12-31

    The common viewpoint or paradigm of the far-field hydraulic fracture geometry is changing. Data sets compiled over the last decade are incompatible with the conventional picture of a single, bi-wing, planar hydraulic fracture. These data sets include (1) recovered cores, (2) minebacks, (3) microseismicity, (4) overcomes and borehole video, (5) treatment pressure response, and (6) surface tilts, in conjunction with advancements in laboratory simulations, studies of natural hydraulic fracture analogues, and improvements in numerical simulations. The single, planar, far-field fracture paradigm finds its roots and development in early theory and simplified laboratory studies that were pre-disposed to single, planar fracture geometry. Replacing the old paradigm is a new perspective that includes a strong potential for creating multiple, far-field fractures. The implications of multiple, far-field fracturing has resulted in adjustments to completion and stimulation strategies to address and affect the overall fracture geometry.

  5. A magnetic method for determining the geometry of hydraulic fractures

    USGS Publications Warehouse

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

    1976-01-01

    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.

  6. Interaction between Hydraulic Fracturing Process and Pre-existing Natural Fractures

    Microsoft Academic Search

    C. Meng

    2010-01-01

    Hydraulic fracturing is employed as a stimulation treatment by the oil and gas industry to enhance the hydro-carbon recoveries. The rationale is that by creating fractures from the wellbore into the surrounding formations, the conductivity between the well and reservoir is significantly increased and the hydro-carbon flow is therefore stimulated. The hydraulic fracture is initiated and driven by pressurizing a

  7. The use of the fracture reopening pressure in hydraulic fracturing stress measurements

    Microsoft Academic Search

    J. L. Ratigan

    1992-01-01

    Summary Practitioners of the hydraulic fracture stress measurement technique commonly estimate the hydraulic fracture tensile strength as the difference between the initial formation breakdown pressure and the fracture reopening pressure. This method, first suggested by Bredehoeft et al. (1976), was developed with the assumption that the stress state in the cracked formation is identical to the stress state in the

  8. Sensors for hydraulic-induced fracturing characterization

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  9. Hydraulic Fracture Propagation with 3-D Leak-off

    Microsoft Academic Search

    Simon A. Mathias; Maarten van Reeuwijk

    2009-01-01

    Hydraulic fracture models typically couple a fracture elasticity model with a geological reservoir model to forecast the rate\\u000a of fluid leak-off from the propagating fracture. The most commonly used leak-off model is that originally specified by Carter,\\u000a which involves the assumption that the fracture is embedded within an infinite homogenous porous medium where flow only occurs\\u000a perpendicular to the fracture

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

    E-print Network

    Santiago Molina, Cesar Alfonso

    1991-01-01

    . . . . , . 2 3 . . . . . 3 . . . . 4 . . . . 4 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 Application of Logs. Reservoir Rock Composition Porosity and Permeability Shale or Clay Distribution in Shaly Sands . Effects of Clays on Log Response Shale Volume... clay in sandstones . . . 14 2. 5. Effect of authigenic pore clays (dispersed) on permeability to air. . . . . . . . 15 3. 1 Flow periods in a vertically fractured well 24 3. 2. Typical pressure behavior for a hydraulically fractured reservoir...

  11. On the problem of fluid leakoff during hydraulic fracturing

    Microsoft Academic Search

    Michael J. Economides; Dmitry N. Mikhailov; Victor N. Nikolaevskiy

    2007-01-01

    While a hydraulic fracture is propagating, fluid flow and associated pressure drops must be accounted for both along the fracture\\u000a path and perpendicularly, into the formation that is fractured, because of fluid leakoff. The accounting for the leakoff shows\\u000a that it is the main factor that determines the crack length. The solved problem is useful for the technology of hydraulic

  12. Active and passive seismic imaging of a hydraulic fracture in diatomite

    SciTech Connect

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

    1992-01-01

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

  13. 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

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

    2004-01-01

    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

  14. Mixed-mode Mechanism of Hydraulic Fracture Segmentation

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    SciTech Connect

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

    1997-03-01

    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.

  16. Advanced hydraulic fracturing methods to create in situ reactive barriers

    SciTech Connect

    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

    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.

  17. Subcritical growth of natural hydraulic fractures

    NASA Astrophysics Data System (ADS)

    Garagash, D.

    2014-12-01

    Joints are the most common example of brittle tensile failure in the crust. Their genesis at depth is linked to the natural hydraulic fracturing, which requires pore fluid pressure in excess of the minimum in situ stress [Pollard and Aidyn, JSG1988]. Depending on the geological setting, high pore pressure can result form burial compaction of interbedded strata, diagenesis, or tectonics. Common to these loading scenarios is slow build-up of pore pressure over a geological timescale, until conditions for initiation of crack growth are met on favorably oriented/sized flaws. The flaws can vary in size from grain-size cracks in igneous rocks to a fossil-size flaws in clastic rock, and once activated, are inferred to propagate mostly subcritically [Segall JGR 1984; Olson JGR 1993]. Despite many observational studies of natural hydraulic fractures, the modeling attempts appear to be few [Renshaw and Harvey JGR 1994]. Here, we use boundary integral formulation for the pore fluid inflow from the permeable rock into a propagating joint [Berchenko et al. IJRMMS 1997] coupled with the criteria for subcritical propagation assisted by the environmental effects of pore fluid at the crack tip to solve for the evolution of a penny-shape joint, which, in interbedded rock, may eventually evolve to short-blade geometry (propagation confined to a bed). Initial growth is exceedingly slow, paced by the stress corrosion reaction kinetics at the crack tip. During this stage the crack is fully-drained (i.e. the fluid pressure in the crack is equilibrated with the ambient pore pressure). This "slow" stage is followed by a rapid acceleration, driven by the increase of the mechanical stress intensity factor with the crack length, towards the terminal joint velocity. We provide an analytical expression for the latter as a function of the rock diffusivity, net pressure loading at the initiation (or flaw lengthscale), and parameters describing resistance to fracture growth. Due to a much slower rate of the crack volume expansion of short-blade joints compared to that of penny-shape joints, the former would propagate much faster than the latter under otherwise identical conditions. Finally, we speculate about possible relation of the predicted patterns of joint development with morphology of joint fracture surfaces observed in sedimentary rock.

  18. Extending behavior of hydraulic fracture when reaching formation interface

    Microsoft Academic Search

    Haifeng Zhao; Mian Chen

    2010-01-01

    Stopping extension, extending along formation interface and directly penetrating into bounding layer are three possible reactions of fracture extension when hydraulic fractures reach formation interfaces. The three types of extending behavior are analyzed using rock fracture mechanics and three respective judging criterions are presented. Layered earth stress, layered rock mechanics parameters, formation interface effect, reservoir thickness and operating parameters are

  19. Modelling the propagation of waterflood induced hydraulic fractures

    Microsoft Academic Search

    J. Hagoort; B. D. Weatherill; A. Settari

    1978-01-01

    A mathematical reservoir model is presented to simulate the propagation of waterflood induced hydraulic fractures in a symmetry element of a waterflood pattern. The model consists of a conventional single phase reservoir simulator coupled with an analytical fracture model. The model is capable of simulating fracture propagation as a function of (1) injection and production rates or pressures, (2) reservoir

  20. Field Application of Hydraulic Impedance Testing for Fracture Measurement

    Microsoft Academic Search

    R. W. Paige; L. R. Murray; J. D. M. Roberts

    1995-01-01

    Hydraulic impedance testing (HIT) is a technique for detecting and measuring formation fractures intersecting wellbores. A pressure pulse is introduced into a well, and the resulting pressure trace is interpreted to give fracture dimensions. The first part of this paper describes how HIT can be used to estimate fracture dimensions and presents some results from a laboratory experiment that show

  1. Hydraulic fracturing theoretical principles, laboratory research, field tests

    Microsoft Academic Search

    Baron

    1967-01-01

    In the past, experimental investigations into hydraulic fracturing have very often been at variance with theoretical principles and results obtained in the field. Technological progress has made it possible to carry out significant experimental investigations both on rocks and on models and to determine fracturing pressures, direction and propagation of fractures, effect of stresses, and effect of stratigraphy. A method

  2. Advanced hydraulic fracturing methods to create in situ reactive barriers

    SciTech Connect

    Murdoch, L. [FRx Inc., Cincinnati, OH (United States); [Clemson Univ., SC (United States); Siegrist, B. [Oak Ridge National Lab., TN (United States); Vesper, S. [Univ. of Cincinnati, OH (United States)] [and others

    1997-12-31

    Many contaminated areas consist of a source area and a plume. In the source area, the contaminant moves vertically downward from a release point through the vadose zone to an underlying saturated region. Where contaminants are organic liquids, NAPL may accumulate on the water table, or it may continue to migrate downward through the saturated region. Early developments of permeable barrier technology have focused on intercepting horizontally moving plumes with vertical structures, such as trenches, filled with reactive material capable of immobilizing or degrading dissolved contaminants. This focus resulted in part from a need to economically treat the potentially large volumes of contaminated water in a plume, and in part from the availability of construction technology to create the vertical structures that could house reactive compounds. Contaminant source areas, however, have thus far remained largely excluded from the application of permeable barrier technology. One reason for this is the lack of conventional construction methods for creating suitable horizontal structures that would place reactive materials in the path of downward-moving contaminants. Methods of hydraulic fracturing have been widely used to create flat-lying to gently dipping layers of granular material in unconsolidated sediments. Most applications thus far have involved filling fractures with coarse-grained sand to create permeable layers that will increase the discharge of wells recovering contaminated water or vapor. However, it is possible to fill fractures with other compounds that alter the chemical composition of the subsurface. One early application involved development and field testing micro-encapsulated sodium percarbonate, a solid compound that releases oxygen and can create aerobic conditions suitable for biodegradation in the subsurface for several months.

  3. Hydraulic fracture energy budget: Insights from the laboratory

    NASA Astrophysics Data System (ADS)

    Goodfellow, S. D.; Nasseri, M. H. B.; Maxwell, S. C.; Young, R. P.

    2015-05-01

    In this paper we present results from a series of laboratory hydraulic fracture experiments designed to investigate various components of the energy budget. The experiments involved a cylindrical sample of Westerly granite being deformed under various triaxial stress states and fractured with distilled water, which was injected at a range of constant rates. Acoustic emission sensors were absolutely calibrated, and the radiated seismic energy was estimated. The seismic energy was found to range from 7.02E-8% to 1.24E-4% of the injection energy which is consistent with a range of values for induced seismicity from field-scale hydraulic fracture operations. The deformation energy (crack opening) of the sample during hydraulic fracture propagation was measured using displacement sensors and ranged from 18% to 94% of the injection energy. Our results support the conclusion that aseismic deformation is a significant term in the hydraulic fracture energy budget.

  4. Hydraulic Fracturing: Paving the Way for a Sustainable Future?

    PubMed Central

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

    2014-01-01

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

  5. Studies investigate effects of hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Liu, Yuwei; Dong, Ning; Fehler, Mike; Fang, Xinding; Liu, Xiwu

    2015-06-01

    Fractures in reservoirs significantly affect reservoir flow properties in subsequent years, which means that fracture characteristics such as preferred orientation, crack density or fracture compliance, what filling is in the fractures and so on are of great importance for reservoir development. 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 data acquired over naturally fractured reservoirs often reveal the presence of multiple fracture sets. We investigate a case where there are two vertical sets of fractures having differing length scales. One fracture set has length scale that is much smaller than the seismic wavelength but the other has length scale that is similar to the seismic wavelength. We use synthetic data to investigate the ability to infer the properties of the small-scale fractures in the presence of the large-scale fracture set. We invert for the Thomsen-type anisotropic coefficients of the small-scale fracture set by using the difference of the P wave amplitudes at two azimuths, which makes the inversion convex. Then we investigate the influence of the presence of the large-scale fractures on our ability to infer the properties of the small-scale fracture set. Surprisingly, we find that we can reliably infer the fracture density of the small-scale fractures even in the presence of large-scale fractures having significant compliance values. Although the inversion results for Thomsen-type anisotropic coefficients of small-scale fractures for one model are not good enough to figure out whether it is gas-filled or fluid-filled, we can find a big change of Thomsen-type anisotropic coefficient {{\\varepsilon}(V)} between the models in which small-scale fractures are filled with gas and fluid.

  7. Hydraulic fracturing technology: Technology evaluation report and application analysis report

    SciTech Connect

    Banerjee, P.

    1993-08-01

    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 and 1992 at a extraction site in Oak Brook, Illinois, and at a bioremediation site near Dayton, Ohio. The technology was jointly developed by the University of Cincinnati (UC) and the Risk Reduction Engineering Laboratory. Tests were also conducted at UC Center Hill Solid and Hazardous Waste Research (Center Hill) Facility by UC. These tests were conducted to determine the factors affecting soil vapor flow through sand-filled hydraulic fractures.

  8. A Practical Hydraulic Fracturing Model Simulating Necessary Fracture Geometry, Fluid Flow and Leakoff, and Proppant Transport

    Microsoft Academic Search

    Usman Ahmed

    1984-01-01

    Hydraulic fracturing model using various sets of fracture flow\\/geometry equations are available in the industry. The majority of these models assume a constant fracture height selected at the start of the design, and simulate two-dimensional fracture geometry (width and length) and one dimensional fluid flow in both the fracture and the formation. The two-dimensional fracture geometry simulation can lead to

  9. Integration of fracturing dynamics and pressure transient analysis for hydraulic fracture evaluation

    SciTech Connect

    Arihara, N.; Abbaszadeh, M.; Wright, C.A.; Hyodo, M.

    1996-12-31

    This paper presents pre- and post-fracture pressure transient analysis, combined with net fracture pressure interpretation, for a well in a naturally fractured geothermal reservoir. Integrated analysis was performed to achieve a consistent interpretation of the created fracture geometry, propagation, conductivity, shrinkage, reservoir flow behavior, and formation permeability characteristics. The interpreted data includes two-rate pre-frac injection tests, step-rate injection tests, a series of pressure falloff tests, and the net fracturing pressure from a massive fracture treatment. Pressure transient analyses were performed utilizing advanced well test interpretation techniques and a thermal reservoir simulator with fracture propagation option. Hydraulic fracture propagation analysis was also performed Milt a generalized 3-D dynamic fracture growth model simulator. Three major conclusions resulted from the combined analysis: (1) that an increasing number of hydraulic fractures were being simultaneously propagated during the fracture treatment. (2) that the reservoir behaved as a composite reservoir Keith the outer region permeability being greater than the permeability of the region immediately surrounding the wellbore, and (3) that the created fractures extended into the outer region during the fracture treatment but retreated to the inner region several days after stimulation had ceased. These conclusions were apparent from independent pressure transient analysis and from independent hydraulic fracture propagation analysis. Integrated interpretation, however, increased the confidence in these conclusions and greatly aided the quantification of the created hydraulic fracture geometry and characterization of the reservoir permeability.

  10. A laboratory study of hydraulic fracturing breakdown pressure in tablerock sandstone

    Microsoft Academic Search

    Insun Song; Mancheol Suh; Kyoung Sik Won; Bezalel Haimson

    2001-01-01

    We carried out hydraulic fracturing tests in hollow cylinders of Tablerock sandstone subjected to vertical (?\\u000a ?\\u000a ), confining (?\\u000a h\\u000a ) and pore (P\\u000a \\u000a o\\u000a ) pressures. Borehole fluid was injected at a constant flow rate until a peak pressure was reached, and vertical fracture\\u000a was observed. Based on the analysis of pressure-time records, we submit that breakdown occurs

  11. Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, April 1, 1996--June 30, 1996

    SciTech Connect

    Niemeyer, B.L.

    1996-07-29

    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 by fracturing an existing test well. Fracture azimuth will be predicted, in part, by passive seismic monitoring from an offset well during fracture stimulation of the test well.

  12. Water Use for Hydraulic Fracturing: A Texas Sized Problem? 

    E-print Network

    LeClere, David

    2014-01-01

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

  13. Numerical Modeling of Hydraulic Fracturing in Oil Sands

    E-print Network

    2008-11-16

    Hydraulic fracturing is a widely used and e cient technique for enhancing oil extraction from heavy oil sands deposits. ..... displacements, resulted in less oscillation in the analysis ...... simulation of geothermal reservoir formation induced.

  14. Tilmeter hydraulic fracture imaging enhancement project: Progress repeort

    SciTech Connect

    Castillo, D.A. [Lawrence Livermore National Lab., CA (United States); Wright, C.A.; Conant, R.A. [and others

    1995-12-31

    Over half of all oil & gas production wells drilled in the United States depend upon hydraulic fracturing to sustain or enhance production. However, there is no existing technology that allows detailed near-surface imaging of these hydraulically-driven fractures at depths greater than about 5000 feet. To image hydraulic fractures in the 8000`-10,000` depth range, we are currently redesigning tiltmeter tools in order to deploy the instruments deeper to escape the cultural/natural surface noise that often masks the hydrofrac signal. With nearly noise-free data, we should be in a better position to separate the earth-tide signal from the tiltmeter signal and investigate fine-scale hydraulic fracturing processes.

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

    E-print Network

    Liu, Yuwei

    2013-01-01

    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 ...

  16. EPA releases progress report on hydraulic fracturing study

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-01-01

    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.

  17. Fracture opening/propagation behavior and their significance on pressure-time records during hydraulic fracturing

    SciTech Connect

    Takashi Kojima; Yasuhiko Nakagawa; Koji Matsuki; Toshiyuki Hashida

    1992-01-01

    Hydraulic fracturing with constant fluid injection rate was numerically modeled for a pair of rectangular longitudinal fractures intersecting a wellbore in an impermeable rock mass, and numerical calculations have been performed to investigate the relations among the form of pressure-time curves, fracture opening/propagation behavior and permeability of the mechanically closed fractures. The results have shown that both permeability of the fractures and fluid injection rate significantly influence the form of the pressure-time relations on the early stage of fracture opening. Furthermore it has been shown that wellbore pressure during fracture propagation is affected by the pre-existing fracture length.

  18. Optimizing hydraulic fracture design in the diatomite formation, Lost Hills Field

    SciTech Connect

    Nelson, D.G.; Klins, M.A.; Manrique, J.F. [and others

    1996-12-31

    Since 1988, over 1.3 billion pounds of proppant have been placed in the Lost Hills Field of Kern County. California in over 2700 hydraulic fracture treatments involving investments of about $150 million. In 1995, systematic reevaluation of the standard, field trial-based fracture design began. Reservoir, geomechanical, and hydraulic fracture characterization; production and fracture modeling; sensitivity analysis; and field test results were integrated to optimize designs with regard to proppant volume, proppant ramps, and perforating strategy. The results support a reduction in proppant volume from 2500 to 1700 lb/ft which will save about $50,000 per well, totalling over $3 million per year. Vertical coverage was found to be a key component of fracture quality which could be optimized by eliminating perforations from lower stress intervals, reducing the total number of perforations, and reducing peak slurry loading from 16 to 12 ppa. A relationship between variations in lithology, pore pressure, and stress was observed. Point-source, perforating strategies were investigated and variable multiple fracture behavior was observed. The discussed approach has application in areas where stresses are variable; pay zones are thick; hydraulic fracture design is based primarily on empirical, trial-and-error field test results; and effective, robust predictive models involving real-data feedback have not been incorporated into the design improvement process.

  19. The use of broadband microseisms for hydraulic-fracture mapping

    SciTech Connect

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

    1995-12-01

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

  20. Physical and numerical modeling of hydraulic fracture closure

    SciTech Connect

    Pater, C.J. de; Groeneboom, J.; Weijers, L. [Delft Univ. of Technology (Netherlands); Desroches, J. [Schlumberger Cambridge Research (United Kingdom)

    1996-05-01

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

  1. An experimental study of hydraulic fracture propagation in layered rock

    Microsoft Academic Search

    1979-01-01

    Laboratory hydraulic fracture experiments are conducted on monolithologic and dilithologic layered rock specimens as a function of interfacial normal stress to determine the relative influence of the interfacial shear strength (due to the frictional effect of the applied normal stress) and the rock properties on either side of the interface on fracture growth across layer interfaces. In addition, photoelastic experiments

  2. Viscous Fluids Provide Improved Results from Hydraulic Fracturing Treatments

    Microsoft Academic Search

    R. B. Rosene; E. F. Shumaker

    1971-01-01

    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

  3. Hydraulic fracture imaging from the Los Alamos hot dry rock experiment

    SciTech Connect

    Li, Yingping; Cheng, C.H.; Toksoez, N.

    1995-12-31

    The waveform correlation analysis and grid search method have been developed to determine the precise hypocenter locations for a cluster of 157 microearthquakes induced by hydraulic fracturing at Los Alamos Hot Dry Rock (HDR) geothermal site. Among the 157 events, 147 microearthquakes occurred in a tight cluster of dimension of 40 m, roughly defining a vertical hydraulic fracture zone. The length, height, and width of the hydraulic fracture zone are measured to be 40, 35, and 5 m, respectively. The orientation of the fracture zone is estimated about N40{degrees}W. Analysis of temporal-spatial pattern of the induced microseismicity indicates that the fracture zone grows significantly in a two-hour period and it grows toward to the northwest along the fracture zone strike with a growth rate of 0.1-0.2 m per minute. An empirical Green`s function (EGF) method has been used to retrieve relative source time functions (RSTF) and to estimate source parameters for larger induced earthquakes. The RSTFs reveal the source complexity and rupture directivity of induced seismic events. The rupture directivity indicates that the rupture propagates to the northwest, which is consistent with the growth direction of the hydraulic fracture zone determined with seismicity temporal-spatial distribution. The source duration of the induced events ranges from 2-8 ms and source radii are estimated to be 4-12 m. Values of stress drops are from 1-19 bars. Significant variation of stress drops reflects that the stress field heterogeneity within a hydraulic fracture zone extends down to a few meters.

  4. Permeability variation in propped hydraulic fractures with changing fracture stress state in gas reservoirs

    SciTech Connect

    Ochs, D.E.

    1995-12-31

    Most hydraulic fracture design optimization models do not account for any change in the permeability of a propped hydraulic fracture due to the changing stress on the proppant pack with time. The assumption that this change is not significant may cause a serious overprediction of the future production of a fractured well leading to a non-optimal treatment design. This problem is investigated here through the use of an integrated fracture propagation, reservoir production, and economic computer simulation based on published analytical models. This simulation changes the permeability of the hydraulic fracture as the stress on the fracture increases over time, demonstrating the sensitivity of the fracture design optimization process to this parameter in terms of the net present value of the stimulation project.

  5. Numerical solution of sand transport in hydraulic fracturing

    SciTech Connect

    Daneshy, A.A.; Crichlow, H.B. (ed.)

    1980-02-07

    A numerical solution is developed for the deposition of a propping agent inside a hydraulic fracture. Such parameters as fluid leak-off into the formation, increase in sand concentration caused by leak-off, non-Newtonian fracturing fluids, hindered settling velocity, and an up-to-date geometry are taken into consideration. Three examples investigate the proppant deposition for low-, medium-, and high-viscosity fracturing fluids.

  6. Evaluation of a downhole tiltmeter array for monitoring hydraulic fractures

    SciTech Connect

    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

    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.

  7. A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development

    SciTech Connect

    Ahmad Ghassemi

    2003-06-30

    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.

  8. Microcrack model and its significance to hydraulic fracturing and fracture toughness testing

    Microsoft Academic Search

    1980-01-01

    A rock mechanics\\/fracture mechanics model is formulated that describes the probable character of the microcrack zone at a crack tip in rock. Knowledge of the crack tip process zone is an important step in the general understanding of fracture propagation in rock. In particular, it may prove useful in descriptions and models of hydraulic fracture propagation near formation interfaces. Such

  9. Initiation of a secondary hydraulic fracture and its interaction with the primary fracture

    Microsoft Academic Search

    Mohammad A. Aghighi; Sheik S. Rahman

    2010-01-01

    Laboratory and field experiments have shown that secondary fracture treatment along a different direction to the primary hydraulic fracture can increase the recovery of gas from tight sands. Success of a restimulation treatment (secondary fracture treatment) is, however, highly dependent on transient stress distribution around the well. In this paper a numerical poroelastic reservoir model is used to provide a

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

    SciTech Connect

    OzKaya, I.

    1983-03-01

    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 of sedimentation and thickness of the shale layer. Hydraulic fracturing may facilitate migration of petroleum from its source into reservoir rocks. Determination of time and depth of hydraulic fracturing by computer simulation may therefore contribute to the oil potential evaluation in an area.

  11. Transient and Pseudosteady-State Productivity of Hydraulically Fractured Well 

    E-print Network

    Lumban Gaol, Ardhi

    2012-10-19

    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...

  12. Transient and Pseudosteady-State Productivity of Hydraulically Fractured Well

    E-print Network

    Lumban Gaol, Ardhi

    2012-10-19

    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...

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

    E-print Network

    Peirce, Anthony

    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

  14. Type-curve analysis of pressure buildup from vertically fractured wells in low permeability reservoirs

    SciTech Connect

    Not Available

    1982-03-01

    Intercomp has developed a set of type curves for use in analyzing pressure buildup data from vertically fractured wells. The new curves account for the length of time the well was on production before it was shut-in for the buildup test. Estimates of permeability, fracture half-length, and fracture conductivity are given from pressure buildup analysis using the curves. We found that the results from Horner analysis of pressure buildup data from vertically fractured wells are affected by the length of time a well was on production prior to starting the buildup test. Long dimensionless flow times are needed for the Horner straight line to develop. This means that extremely long flow times are needed for Horner analysis to be used on pressure buildup data from massive hydraulic fractured wells in low permeability reservoirs. Several examples are given of analyzing pressure buildup data using the new type curves.

  15. 2006 GeoX Conference, pages 1 to 6 Characterisation of hydraulic fractures in

    E-print Network

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

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

    E-print Network

    Peirce, Anthony

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

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

    E-print Network

    Peirce, Anthony

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

  18. Using seismic tomography to characterize fracture systems induced by hydraulic fracturing

    SciTech Connect

    Fehler, M.; Rutledge, J.

    1995-01-01

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

  19. Estimating the hydraulic conductivity of two-dimensional fracture networks

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Most oil and gas reservoirs, as well as most potential sites for nuclear waste disposal, are naturally fractured. In these sites, the network of fractures will provide the main path for fluid to flow through the rock mass. In many cases, the fracture density is so high as to make it impractical to model it with a discrete fracture network (DFN) approach. For such rock masses, it would be useful to have recourse to analytical, or semi-analytical, methods to estimate the macroscopic hydraulic conductivity of the fracture network. We have investigated single-phase fluid flow through stochastically generated two-dimensional fracture networks. The centres and orientations of the fractures are uniformly distributed, whereas their lengths follow either a lognormal distribution or a power law distribution. We have considered the case where the fractures in the network each have the same aperture, as well as the case where the aperture of each fracture is directly proportional to the fracture length. The discrete fracture network flow and transport simulator NAPSAC, developed by Serco (Didcot, UK), is used to establish the “true” macroscopic hydraulic conductivity of the network. We then attempt to match this conductivity using a simple estimation method that does not require extensive computation. For our calculations, fracture networks are represented as networks composed of conducting segments (bonds) between nodes. Each bond represents the region of a single fracture between two adjacent intersections with other fractures. We assume that the bonds are arranged on a kagome lattice, with some fraction of the bonds randomly missing. The conductance of each bond is then replaced with some effective conductance, Ceff, which we take to be the arithmetic mean of the individual conductances, averaged over each bond, rather than over each fracture. This is in contrast to the usual approximation used in effective medium theories, wherein the geometric mean is used. Our explanation is that the conductivities of the bonds that meet at a given node in a fracture network do not satisfy the usual assumption of being uncorrelated; rather, the conductances of at least two of these bonds are highly correlated, as they represent the incoming and outgoing branches of the same fracture. The effective conductance of our idealized “equivalent network” is then trivial to calculate. We find that this estimate of the hydraulic conductivity agrees very closely with the numerically computed value, essentially for all fracture densities that are not too close to the percolation threshold. Moreover, the same methodology applies regardless of whether the fracture lengths are distributed lognormally, or according to a power law.

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

    E-print Network

    Marpaung, Fivman

    2008-10-10

    (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...

  1. Field application of hydraulic impedance testing for fracture measurement

    SciTech Connect

    Paige, R.W.; Murray, L.R.; Roberts, J.D.M. (BP Exploration, Sunbury (United Kingdom))

    1995-02-01

    Hydraulic impedance testing (HIT) is a technique for detecting and measuring formation fractures intersecting wellbores. A pressure pulse is introduced into a well, and the resulting pressure trace is interpreted to give fracture dimensions. The first part of this paper describes how HIT can be used to estimate fracture dimensions and presents some results from a laboratory experiment that show that dimensions can be measured accurately with HIT. The remainder of the paper describes field examples of the application of HIT. A demonstration of how HIT traces change as pressure is reduced, which provides a method for determining fracture closure pressure, is included.

  2. Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

    SciTech Connect

    Stephen Holditch; A. Daniel Hill; D. Zhu

    2007-06-19

    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.

  3. 77 FR 40354 - Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel Fuels-Draft

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-09

    ...Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel Fuels...Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel Fuels...Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using Diesel...

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

    E-print Network

    Wythe, Kathy

    2013-01-01

    of Drinking Water) Steel casing lines the well and is cemented in place to prevent any communication up the wellbore as the fracturing job is pumped or the well is produced. Shallow formations holding freshwater that may be useful for farming... agent is pumped in to prop open the fracture,? he said. ?It creates pathways for the oil and gas to #14;ow from the reservoir back to the surface.? Water use in hydraulic fracturing #31;e amount of water used in hydraulic fracturing is a major...

  5. Hydraulic tomography offers improved imaging of heterogeneity in fractured rocks.

    PubMed

    Illman, Walter A

    2014-01-01

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

  6. In situ bioremediation of petroleum in tight soils using hydraulic fracturing

    SciTech Connect

    Stavnes, S. [Environmental Protection Agency, Denver, CO (United States); Yorke, C.A. [Foremost Solutions, Inc., Golden, CO (United States); Thompson, L. [Pintail Systems, Inc., Aurora, CO (United States)

    1996-12-31

    This case study evaluated the effectiveness of in situ bioremediation of petroleum hydrocarbons in tight soils. The study area was contaminated with cutting oil from historic releases from underground piping, probably dating back to the 1940`s. Previous site assessment work indicated that the only chemicals of concern were total petroleum hydrocarbons (TPH). Two fracture sets (stacks) were installed at different locations to evaluate this in situ bioremediation technique under passive and active conditions. Several injection wells were drilled at both locations to provide entry for hydraulic fracturing equipment. A series of circular, horizontal fractures 40 to 50 feet in diameter were created at different depths, based on the vertical extent of contamination at the site. The injection wells were screened across the contaminated interval which effectively created underground bioreactors. Soils were sampled and analyzed for total petroleum hydrocarbons on five separate occasions over the nine-month study. Initial average soil concentrations of total petroleum hydrocarbons of 5,700 mg/kg were reduced to 475 mg/kg within nine months of hydraulic fracturing. The analytical results indicate an average reduction in TPH at the sample locations of 92 percent over the nine-month study period. This project demonstrates that in situ bioremediation using hydraulic fracturing has significant potential as a treatment technology for petroleum contaminated soils.

  7. Radiographic features of vertically fractured, endodontically treated maxillary premolars

    Microsoft Academic Search

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

    1999-01-01

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

  8. Water management in hydraulic fracturing-a planning and decision optimization platform

    E-print Network

    Mehta, Neha, S.M. Massachusetts Institute of Technology

    2014-01-01

    Recent developments in hydraulic fracturing technology have enabled cost-effective production of unconventional resources, particularly shale gas in the U.S. The process of hydraulic fracturing is water intensive, requiring ...

  9. 75 FR 36387 - Informational Public Meetings for Hydraulic Fracturing Research Study; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-25

    ...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...

  10. Monitoring the width of hydraulic fractures with acoustic waves

    SciTech Connect

    Groenenboom, J.; Fokkema, J.T. [Delft Univ. of Technology (Netherlands)] [Delft Univ. of Technology (Netherlands)

    1998-01-01

    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 indirect dispersion measurement method however, extends to a fracture width that is in the order of 1% of the incident wavelength. The time-lapse ultrasonic measurements allow one to relate the small difference in arrival time and amplitude between two measurements solely to the small changes in the width of the fracture. Additional experimental data show that shear waves are completely shadowed by hydraulic fractures, indicating that there is no acoustic contact mechanism at the fracture interface. Therefore the authors think it is appropriate to use a thin fluid-filled layer model for these hydraulic fractures instead of the standard empirically oriented linear slip model. Nevertheless, the thin layer model is consistent with the linear-slip model, if interpreted correctly. A comparison of width measurements inside the well-bore and width estimates by means of dispersion measurements close to the wellbore shows that the method can be successfully applied, at least under laboratory conditions, and that small changes in the width of the fracture are directly expressed in the dispersion of the transmitted signal. This opens the way for the important new application of width monitoring of hydraulic fractures.

  11. Experimental verification of dimensional analysis for hydraulic fracturing

    SciTech Connect

    Pater, C.J. de; Weijers, L. (Delft Univ. of Technology (Netherlands)); Cleary, M.P.; Quinn, T.S. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Barr, D.T.; Johnson, D.E. (Resources Engineering Systems, Inc., Cambridge, MA (United States))

    1994-11-01

    The authors have derived model laws that relate experimental parameters of a physical model of hydraulic fracture propagation to the prototype parameters. Correct representation of elastic deformation, fluid friction, crack propagation, and fluid leakoff forms the basis of the scaling laws. For tests at in-situ stress, high fluid viscosity and low fracture toughness are required. Tests on cement blocks agreed with the scale laws based on elastic behavior.

  12. Characterizing Fracture Connectivity and Hydraulic Conductivity Heterogeneity in Sedimentary Rocks Using Hydraulic Tomography

    NASA Astrophysics Data System (ADS)

    Tiedeman, C. R.

    2013-12-01

    At sites of groundwater contamination in fractured rocks, detailed characterization of flow paths and hydraulic properties at small spatial scales is critical for designing and monitoring remediation. Characterization remains a challenge owing to the extreme hydraulic conductivity heterogeneity of fractured rock aquifers combined with the expense of installing boreholes in these systems. Hydraulic tomography - conducting and analyzing multiple short-duration cross-hole aquifer tests in discrete borehole intervals - holds promise for achieving the degree of characterization needed in contaminated fractured rocks and for maximizing the flow system information gained from a set of boreholes. A hydraulic tomography experiment was performed in shallow dipping fractured mudstones at a contaminated site in the Newark Basin near Trenton, NJ, using a network of seven boreholes separated by horizontal distances of 4.5 to 9 m. Pneumatic packers were installed to separate each open borehole into three or four isolated intervals. Thirteen one-hour aquifer tests were conducted by pumping from intervals intersected by permeable fractures, while continuously measuring drawdown in all isolated intervals. The test data are being analyzed using numerical groundwater flow models and inverse methods to estimate the hydraulic conductivity distribution in the rock. In this sedimentary rock system, high-permeability bedding-plane-parting fractures often can be inferred from qualitative analysis of the drawdown data. This information, together with the detailed geologic framework model for the site, can be used to guide the representation of heterogeneity within beds in the flow models. The drawdowns also suggest that connectivity between the bedding plane fractures occurs along permeable cross-bed fractures. Determining the locations of these cross-bed fractures is much more difficult, partly because the geologic framework typically does not provide clues to their whereabouts. Inverse modeling of the hydraulic tomography data is being tested for its ability to estimate the locations of these fractures, which are important to identify because of their strong control on contaminant transport and remediation. Subsurface view of boreholes at which hydraulic tomography experiment was conducted. Red and blue regions depict high-permeability bedding-plane-parting fracture zones.

  13. The use of broadband microseisms for hydraulic fracture mapping

    SciTech Connect

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

    1993-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  15. Laboratory hydraulic fracturing experiments in intact and pre-fractured rock

    USGS Publications Warehouse

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

    1977-01-01

    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 a marked effect on breakdown pressures, the pressure at which hydraulic fractures initiate (and thus tensile strength) is independent of the rate of borehole pressurization when the effect of fluid penetration is negligible. Thus, the experiments indicate that use of breakdown pressures rather than fracture initiation pressures may lead to an erroneous estimate of tectonic stresses. A conceptual model is proposed to explain anomalously high breakdown pressures observed when fracturing with high viscosity fluids. In this model, initial fracture propagation is presumed to be stable due to large differences between the borehole pressure and that within the fracture. In samples which contained pre-existing fractures which were 'leaky' to water, we found it possible to generate hydraulic fractures oriented parallel to the direction of maximum compression if high viscosity drilling mud was used as the fracturing fluid. ?? 1977.

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

    E-print Network

    Wythe, Kathy

    2013-01-01

    of Fracture Fluid Performance in Oil Shale with Surfactant Additives by X-Ray Tomography Methods (Crisman Institute: Schechter) Re-Use of Produced Waters as Hydraulic Fracturing Fluids (Crisman Institute: Nasr-El-Din) In a joint House Commi#20;ee...

  17. 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

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

    E-print Network

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

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

    E-print Network

    Foulger, G. R.

    Click Here for Full Article Imaging hydraulic fractures in a geothermal reservoir Bruce R. Julian,1, B. R., G. R. Foulger, F. C. Monastero, and S. Bjornstad (2010), Imaging hydraulic fractures that seismological techniques can provide information of high quality about hydraulic fractures that are of potential

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

    E-print Network

    Peirce, Anthony

    2007-01-01

    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

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

    E-print Network

    Peirce, Anthony

    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 OðhÞ accuracy. For hydraulic fracture problems with a lag separating

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

    E-print Network

    Peirce, Anthony

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

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

    E-print Network

    Paris-Sud XI, Université de

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

  4. The effects of aqueous chemical environments on crack and hydraulic fracture propagation and morphologies

    Microsoft Academic Search

    J. D. Dunning; W. L. Huf

    1983-01-01

    The role of surface active aqueous environments in chemomechanical weakening of geologic materials is examined in light of the results of hydraulic fracture tests in sandstone, calorimetric studies, and crack propagation tests in synthetic quartz. In hydraulic fracture tests employing Crab Orchard Sandstone it was found that the effective hydraulic fracture pressure was reduced, over that attained with distilled water,

  5. Effects of aqueous chemical environments on crack and hydraulic fracture propagation and morphologies

    Microsoft Academic Search

    J. D. Dunning; W. L. Huf

    1983-01-01

    The role of surface active aqueous environments in chemomechanical weakening of geologic materials is examined using the results of hydraulic fracture tests in sandstone, calorimetric studies, and crack propagation tests in synthetic quartz. In hydraulic fracture tests it was found that the effective hydraulic fracture pressure was reduced, over that attained with distilled water, when 5 X 10⁻⁴ M aqueous

  6. 77 FR 38024 - Oil and Gas; Well Stimulation, Including Hydraulic Fracturing, on Federal and Indian Lands

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-26

    ...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...

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

    E-print Network

    Foulger, G. R.

    2012-01-01

    propagating stimulated hydraulic fractures, gener- ated by fracking operations for gas and oil exploitation contamination of drinking water in the USA and to provide an evidence base for the safe vertical separation distance between shale reservoirs and aquifers. The contamination hypothesis was explicit in the title

  8. Borehole Geophysics, Hydraulic Characteristics and Chemistry of Groundwater Flow in Fractured Granite With Very Low Permeability

    NASA Astrophysics Data System (ADS)

    Lukes, J.; Rukavickova, L.; Paces, T.

    2005-12-01

    Three test boreholes 10.9 and 10.5 meters apart were drilled in a compact granite at locality Podles' in the Bohemian Massif of central Europe. The depths of the drill boreholes were 349, 300 and 296 m. The location of the boreholes form a triangle. The main goal of this study was to determine the degree to which the very compact granite is fractured and what is the hydraulic conductivity of the fracture system. A combination of neutron log, electrical resistivity logs, gama gama log, fluid-resistivity log, and acoustic log was used to test the function of the fracture system. The hydraulic connection among the boreholes was determined from the fluid-resistivity log using injected salt as a tracer. The pressure communication through fractures among boreholes was investigated by a set of water pressure tests (WPT) in one borehole with simultaneous monitoring of responses in the other two holes equipped by a multipacker system. The connection of selected permeable fracture systems was verified by a combination of hydraulic stress tests in one borehole and simultaneous fluid-resistivity logging in other two boreholes. Indication of salt in water in adjoining boreholes was registered as anomalies on curves of the fluid-resistivity record. Several communications between boreholes were along a horizontal level, however, some connections were through combination of both horizontal and vertical fractures. The hydraulic connection between two of the boreholes was fast and straightforward. The connection with the third borehole was inexpressive. This difference was due to the position of the boreholes with regard to the direction of main fractures and the direction of natural groundwater flow. All fractures were identified using acoustic tele-viewer and inspection of core. The density of the fractures varied with depth. The density was 3 fractures per meter near surface, the density dropped to 0.9 fractures per meter at the depth of 80 m. Between 80 and 300 m, the density increased with depth to the maximum of 8.8 fractures per meter. The hydraulic conductivity of the fractured granite was investigated with WPT and slug tests. We measured the water loss at pressures 2.7x10-1 and 4.5x10-1 MPa. The water loss was tested in sections separated with the packers. The thickness of the sections varied from 1 to 50 meters. The water loss below 150 m was extremely low from 5x10-5 to 4x10-4 liters per minute per meter. Above 100 m depth the water loss varied from 3x10-3 to 7x10-1 L/min/m. The weathered zone to a depth of 25 m had a permeability of 2x10-6 m/s. The zone of opened fractures reached to a depth of 95 m with permeability from 2x10-9 to 2x10-7 m/s. Granite below 95 m had a dense net of fractures, however, the fractures were closed so that the permeability was very low from 2x10-12 to 4x10-9 m/s. After the logging and hydraulic tests, samplers of water were installed in four sections of one of the drill holes. Very small quantities of water are periodically pumped out and analyzed. Electric conductivity and chemical composition of groundwater from the granite returned to a natural composition not affected by injection of salt after several months. Water from the deepest section (230-296 m) reflects the influence of local stream water while water from the shallower sections reflects a prolonged or more intensive interaction with granite. This indicates also the complexity of the fracture system. The data are used to build a specific simulation model to represent groundwater flow and water-rock interaction in fractured granite.

  9. Analytic crack solutions for tilt fields around hydraulic fractures

    SciTech Connect

    Warpinski, N.R.

    2000-01-05

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

  10. Investigation of Created Fracture Geometry through Hydraulic Fracture Treatment Analysis 

    E-print Network

    Ahmed, Ibraheem 1987-

    2012-11-30

    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...

  11. Leakage losses from a hydraulic fracture and fracture propagation

    Microsoft Academic Search

    Robert E. Johnson; Craig W. Gustafson

    1988-01-01

    The fluid mechanics of viscous fluid injection into a fracture embedded in a permeable rock formation is studied. Coupling between flow in the fracture and flow in the rock is retained. The analysis is based on a perturbation scheme that assumes the depth of penetration of the fluid into the rock is small compared to the characteristic length w30\\/k, where

  12. Leakage losses from a hydraulic fracture and fracture propagation

    Microsoft Academic Search

    Robert E. Johnson; Craig W. Gustafson

    1988-01-01

    The fluid mechanics of viscous fluid injection into a fracture embedded in a permeable rock formation is studied. Coupling between flow in the fracture and flow in the rock is retained. The analysis is based on a perturbation scheme that assumes the depth of penetration of the fluid into the rock is small compared to the characteristic length w³â\\/k, where

  13. GEOL440, GEOL524 Sedimentary Geology: Hydraulic Fracturing Seminar

    E-print Network

    Nickrent, Daniel L.

    -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

  14. 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

  15. Water Use for Hydraulic Fracturing: A Texas Sized Problem?

    E-print Network

    LeClere, David

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

  16. 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...

  17. Imaging hydraulic fractures using temperature transients in the Belridge Diatomite

    SciTech Connect

    Shahin, G.T.; Johnston, R.M.

    1995-12-31

    Results of a temperature transient analysis of Shell`s Phase 1 and Phase 2 Diatomite Steamdrive Pilots are used to image hydraulic injection fracture lengths, angles, and heat injectivities into the low-permeability formation. The Phase 1 Pilot is a limited-interval injection test. In Phase 2, steam is injected into two 350 ft upper and lower zones through separate hydraulic fractures. Temperature response of both pilots is monitored with sixteen logging observation wells. A perturbation analysis of the non-linear pressure diffusion and heat transport equations indicates that at a permeability of about 0.1 md or less, heat transport in the Diatomite tends to be dominated by thermal diffusivity, and pressure diffusion is dominated by the ratio of thermal expansion to fluid compressibility. Under these conditions, the temperature observed at a logging observation well is governed by a dimensionless quantity that depends on the perpendicular distance between the observation well and the hydraulic fracture, divided by the square root of time. Using this dependence, a novel method is developed for imaging hydraulic fracture geometry and relative heat injectivity from the temperature history of the pilot.

  18. Numerical modeling of hydraulic fracture initiation and development

    E-print Network

    2007-05-25

    Studying initiation and propagation of hydraulic fractures is carried out based on the ... an unsteady flow from a rock to a crack, that causes change in a stress state and .... To date, by the modeling method, it is possible to determine the onset ...

  19. A Political Ecology of Hydraulic Fracturing for Natural Gas in

    E-print Network

    Scott, Christopher

    ! Background of Marcellus Shale Gas Play ! Current Events: The Case of PA ! Geography of Fracking in Study-site to municipal WWTPs · Regional public health and resource values are reduced to a cost/benefit scenario. #12 are the environmental health impacts? #12;A political ecology of hydraulic fracturing Why this approach? ­Water quantity

  20. Analyses of an Elmworth Hydraulic Fracture in Alberta

    Microsoft Academic Search

    R. E. Wyman; S. A. Holditch; P. L. Randolph

    1980-01-01

    The Elmworth gas field in Alberta's Deep basin could hold more than 400 trillion CF of recoverable gas reserves. To obtain more information on the economics and technology required to produce this gas, Canadian engineers performed a large (700-ft) hydraulic foam fracture over the Cretaceous Falher Zones A and B in a tight sand having an in situ permeability of

  1. Hydraulic Fracturing Expert Team from Colorado State University Bill Ritter

    E-print Network

    and Environmental Engineering at Colorado State University with over 20 years of experience in water treatment1 Hydraulic Fracturing Expert Team from Colorado State University Bill Ritter Colorado's 41st of a clean energy economy across the United States at Colorado State University. The mission of the Center

  2. Numerical Modeling of Fluid Migration and Propagation of Multiple Hydraulic Fractures in Crystalline Geothermal Reservoir

    NASA Astrophysics Data System (ADS)

    Yoon, Jeoung Seok; Zang, Arno; Zimmermann, Günter; Stephansson, Ove; Min, Ki-Bok

    2015-04-01

    This paper presents discrete element based numerical model which is applied to simulation of multiple stage hydraulic fracturing in crystalline granitic geothermal reservoir. Target site modeled locates in south of state of Saxony Germany. Particle Flow Code 2D (Itasca) is used in which fluid flow algorithm and moment tensor based seismicity computation algorithm are implemented. Crystalline rock layer to be stimulated locates at 4-6 km depth with relative low density of pre-existing joints and faults. Hydraulic stimulation is modeled with five stages of fluid injection with distance of several hundreds of meters. Hydraulic fracturing is done on the stages from toe to heel direction along a series of sub-horizontally drilled wellbore with constant rate of fluid injection. Fracture propagation paths and induced seismic events are documented based on their time of occurrence and their magnitude. In addition to the evolution of the fracture propagation path and distribution of the induced events, migration of the injected fluid is investigated in space and time. This is to see how the results relate to the fluid migration front in low permeability crystalline reservoir subjected to multiple stage hydraulic fracturing. Moreover, this paper addresses advantages and disadvantages of the inclined drilling of the wellbore in low permeability reservoir and multi-stage fracturing setting. We try to seek an optimum inclination of the drilling in relation to the gradients and magnitudes of the in situ stresses, which are horizontal minimum and vertical stresses. Preliminary modeling results show that inclination angle of the drilling has a significant effect on lowering of the stress shadow effect and level of induced seismicity in terms of total number, magnitudes and the Gutenberg-Richter relation.

  3. Hydraulic Aperture Reduction of Shale Fractures Due to Mechanical Stressing, with Characterization of Physical Fracture Evolution Using Comuted Tomography

    NASA Astrophysics Data System (ADS)

    Crandall, D.; Gill, M.; Moore, J.

    2014-12-01

    Flow in fractured shale is a topic of interest for both production from non-traditional fractured shale reservoirs and for estimating the leakage potential of sealing formations above geologic carbon dioxide repositories. The hydraulic aperture of a fracture quantifies how much fluid can be transported through a fracture, similarly to how permeability describes fluid flow through porous media. The advantage of defining the fracture hydraulic aperture as opposed to permeability, is that this property can be easily scaled up to fracture reservoir simulators. Many parameters affect the hydraulic aperture, however, including the fracture roughness, the physical aperture distribution, and the tortuosity of flow paths within the fracture.The computed tomography (CT) and flow facility at NETL has conducted an analysis of the changes in both physical and hydraulic aperture as fractures were subjected to varying external confining stresses. Changes in fracture geometry were tracked through the use of non-destructive CT imaging, allowing the determination of the physical aperture distribution, while hydraulic fracture apertures were derived from experimental fracture flow measurements. In order to evaluate the effects of fracture roughness and geometry, two fractures with different degrees of roughness were used. Tests were conducted with locally sourced shale.Experimental results show that the volume change in the fracture is a non-linear function of the confining pressure, and both physical and hydraulic apertures decrease rapidly as the fracture is first compressed.

  4. Formation permeability determination by micro or mini-hydraulic fracturing

    SciTech Connect

    Abousleiman, Y. (Univ. of Oklahoma, Norman, OK (United States). School of Petroleum and Geological); Cheng, A.H.D. (Univ. of Delaware, Newark, DE (United States). Dept. of Civil Engineering); Gu, H. (Dowell Schlumberger Inc., Tulsa, OK (United States))

    1994-06-01

    This paper presents a theory and its application for post-fracture pressure-transient analyses. The proposed procedure, known as impulse fracture test,'' is an injection/falloff test designed for the determination of formation permeability and reservoir pressure. The hydraulically induced fracture can pass the near wellbore damaged zone and expose a larger formation area to flow. The permeability and reservoir pressure determined are therefore more representative of the reservoir. The theory is based on the distribution of sources with variable intensity along the fracture trajectory. For field applications, asymptotic solutions are derived to give the type-curve'' capability for the estimation of formation permeability and reservoir pressure. Assorted slope behaviors, such as [minus]1, [minus]2, +1/2 and +1 slopes, are predicted from various pressure and pressure derivative plots. Analyses of data from two wells which were inadvertently fractured support these behaviors.

  5. Engineering geological characteristics and the hydraulic fracture propagation mechanism of the sand-shale interbedded formation in the Xu5 reservoir

    NASA Astrophysics Data System (ADS)

    Lu, Cong; Li, Mei; Guo, Jian-Chun; Tang, Xu-Hai; Zhu, Hai-Yan; Yong-Hui, Wang; Liang, Hao

    2015-06-01

    In the Xu5 formation the sandstone reservoir and the shale reservoir are interbedded with each other. The average thickness of each formation is about 8?m, which increases the difficulty of the hydraulic fracturing treatment. The shale thickness ratio (the ratio of shale thickness to formation thickness) is 55–62.5%. The reservoir is characterized by ultra-low porosity and permeability. The brittleness index of sandstone is 0.5–0.8, and the brittleness index of shale is 0.3–0.8. Natural fractures are poorly developed and are mainly horizontal and at a low angle. The formation strength is medium and the reservoir is of the hybrid strike-slip fault and reverse fault stress regime. The difference between the minimum principal stress and the vertical stress is small, and the maximum horizontal principal stress is 20?MPa higher than the minimum horizontal principal stress and vertical stress. A mechanical model of a hydraulic fracture encountering natural fractures is built according to geological characteristics. Fracture mechanics theory is then used to establish a hydraulic fracturing model coupling the seepage–stress–damage model to simulate the initiation and propagation of a fracture. The hydraulic fracture geometry is mainly I-shaped and T-shaped, horizontal propagation dominates the extension, and vertical propagation is limited. There is a two to three meter stress diversion area around a single hydraulic fracture. The stress diversion between a hydraulic fracture and a natural fracture is advantageous in forming a complex fracture. The research results can provide theoretical guidance for tight reservoir fracturing design.

  6. Gas condensate damage in hydraulically fractured wells

    E-print Network

    Reza, Rostami Ravari

    2004-11-15

    -vaporize. This region is called the retrograde condensation zone and reservoirs experiencing this phenomenon are known as gas condensate reservoirs 1. 1.2.1 Gas condensate reservoir fluid modeling In compositional simulation of oil and gas reservoirs... Ayoola Adeyeye, this subject was studied when the effects of reservoir depletion were minimized by introduction of an injector well with fluid composition the same as the original reservoir fluid. He also used an infinite conductivity hydraulic...

  7. Vibrational modes of hydraulic fractures: Inference of fracture geometry from resonant frequencies and attenuation

    NASA Astrophysics Data System (ADS)

    Lipovsky, Bradley P.; Dunham, Eric M.

    2015-02-01

    Oscillatory seismic signals arising from resonant vibrations of hydraulic fractures are observed in many geologic systems, including volcanoes, glaciers and ice sheets, and hydrocarbon and geothermal reservoirs. To better quantify the physical dimensions of fluid-filled cracks and properties of the fluids within them, we study wave motion along a thin hydraulic fracture waveguide. We present a linearized analysis, valid at wavelengths greater than the fracture aperture, that accounts for quasi-static elastic deformation of the fracture walls, as well as fluid viscosity, inertia, and compressibility. In the long-wavelength limit, anomalously dispersed guided waves known as crack or Krauklis waves propagate with restoring force from fracture wall elasticity. At shorter wavelengths, the waves become sound waves within the fluid channel. Wave attenuation in our model is due to fluid viscosity, rather than seismic radiation from crack tips or fracture wall roughness. We characterize viscous damping at both low frequencies, where the flow is always fully developed, and at high frequencies, where the flow has a nearly constant velocity profile away from viscous boundary layers near the fracture walls. Most observable seismic signals from resonating fractures likely arise in the boundary layer crack wave limit, where fluid-solid coupling is pronounced and attenuation is minimal. We present a method to estimate the aperture and length of a resonating hydraulic fracture using both the seismically observed quality factor and characteristic frequency. Finally, we develop scaling relations between seismic moment and characteristic frequency that might be useful when interpreting the statistics of hydraulic fracture events.

  8. Influence of Natural Fractures Cohesive Properties on Geometry of Hydraulic Fracture Networks

    NASA Astrophysics Data System (ADS)

    Gonzalez-Chavez, M. A.; Dahi Taleghani, A.; Puyang, P.

    2014-12-01

    An integrated modeling methodology is proposed to analyze hydraulic fracturing jobs in the presence of the natural fracture network in the formation. A propagating hydraulic fracture may arrest, cross, or diverts into a preexisting natural crack depending on fracture properties of rock and magnitude and direction of principal rock stresses. Opening of natural fractures during fracturing treatment could define the effectiveness of the stimulation technique. Here, we present an integrated methodology initiated with lab scale fracturing properties using Double Cantilever Beam tests (DCB) to determine cohesive properties of rock and natural fractures. We used cohesive finite element models to reproduce laboratory results to verify the numerical model for the interaction of the hydraulic fracture and individual cemented natural fractures. Based on the initial investigations, we found out that distribution of pre-existing natural fractures could play a significant role in the final geometry of the induced fracture network; however in practice, there is not much information about the distribution of natural fractures in the subsurface due to the limited access. Hence, we propose a special optimization scheme to generate natural fracture geometry from the location of microseismic events. Accordingly, the criteria of evaluating the fitness of natural fracture realizations is defined as the total minimum distance squares of all microseismic events, which is the sum of minimum square distance for all microseismic events. Moreover, an additional constraint in this problem is that we need to set a minimum distance between fracture grids. Using generated natural fracture realizations, forward field-scale simulations are implemented using cohesive finite element analysis to find the best match with the recorded bottomhole pressure. To show the robustness of the proposed workflow for real field problem, we implemented this technique on available data from several well Chicontepec basin to forecast post-treatment production rate. Our results show a constructive approach to integrate microseismic maps with lab mechanical measurements and bottomhole pressure to estimate the geometry of induced fracture network in the subsurface which does not suffer from any limiting assumption about fracture geometries.

  9. The Use of Hydraulic Head and Atmospheric Tritium to Identify Presence of Fractures in Clayey Aquitards: Numerical Analysis

    NASA Astrophysics Data System (ADS)

    Farah, E. A.; Parker, B. L.; Cherry, J. A.

    2003-12-01

    Surficial clayey aquitards can provide underlying aquifers with strong protection from contamination if vertically connected open fractures are absent. Hence, methods are needed to identify such contaminant pathways. An existing two-dimensional model for steady-state groundwater flow and solute transport (FRACTRAN) was used for cross-sectional simulations to assess the prospects for using field measurements of hydraulic head and atmospheric (i.e. bomb) tritium in surficial aquitards to determine presence and nature of hydraulically connected fractures. Simulations for a 15-m thick horizontal aquitard, with shallow water table and downward groundwater flow, show that field measurements of head and tritium at points appropriately spaced along a horizontal line at the lower part of the aquitard provide unique insight since they offer the highest chance for detecting vertical fractures. Simulations represented sets of predominant vertical and horizontal fractures of uniform aperture (25 æm) and variable length. The simulations focused on fracture-network features assigned based on the literature of field investigations. The horizontal profiles show peaks and troughs for head, and always peaks for tritium concentrations at fracture localities. Use of only head or tritium alone may locate fractures, but may not discover whether each fracture is connected to the ground surface or aquifer top, or both. On the other hand, the coupled patterns of head and tritium can be used to identify fractures more accurately. For example, a head trough and a tritium sharp peak represent a fully penetrating fracture, while a head peak and a rounded-tip tritium peak represent a partially penetrating fracture. Moreover, these two are easily differentiated from an embedded fracture that is represented by a relatively small head trough and a short sharp tritium peak. The method of monitoring along a horizontal line was applied to the conceptual 15-m thick aquitard imitating horizontal groundwater head monitoring and formation sampling events at different spacing intervals. The modeling indicates that, monitoring at 3-m spacing along a line at an elevation positioned deep in the aquitard locates and determines connectivity of most vertical fractures. Moreover, it may be possible from measured tritium distributions in aquitards to estimate the depth of hydraulically active partially penetrating fractures. Thus, horizontal monitoring is a valuable complement to vertical monitoring nests in the study of aquitard integrity.

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

    E-print Network

    Berthelot, Jan Marie

    1990-01-01

    fracture treatment, a large volume of fracturing fluid is pumped into the formation at high rates. The fracturing fluid is often a high viscosity, water-based, proppant-laden polymer gel. By pumping into the formation, the pressure in the wellbore... was not. The upper zone was hydraulically fractured using 78, 000 gal of a delayed crosslinked gelled water and 87, 500 lb of 18-20 mesh intermediate strength proppant. The well was swabbed for 1-1/2 days before it began to flow gas and water. After 4...

  11. Aerobic biodegradation of organic compounds in hydraulic fracturing fluids.

    PubMed

    Kekacs, Daniel; Drollette, Brian D; Brooker, Michael; Plata, Desiree L; Mouser, Paula J

    2015-07-01

    Little is known of the attenuation of chemical mixtures created for hydraulic fracturing within the natural environment. A synthetic hydraulic fracturing fluid was developed from disclosed industry formulas and produced for laboratory experiments using commercial additives in use by Marcellus shale field crews. The experiments employed an internationally accepted standard method (OECD 301A) to evaluate aerobic biodegradation potential of the fluid mixture by monitoring the removal of dissolved organic carbon (DOC) from an aqueous solution by activated sludge and lake water microbial consortia for two substrate concentrations and four salinities. Microbial degradation removed from 57 % to more than 90 % of added DOC within 6.5 days, with higher removal efficiency at more dilute concentrations and little difference in overall removal extent between sludge and lake microbe treatments. The alcohols isopropanol and octanol were degraded to levels below detection limits while the solvent acetone accumulated in biological treatments through time. Salinity concentrations of 40 g/L or more completely inhibited degradation during the first 6.5 days of incubation with the synthetic hydraulic fracturing fluid even though communities were pre-acclimated to salt. Initially diverse microbial communities became dominated by 16S rRNA sequences affiliated with Pseudomonas and other Pseudomonadaceae after incubation with the synthetic fracturing fluid, taxa which may be involved in acetone production. These data expand our understanding of constraints on the biodegradation potential of organic compounds in hydraulic fracturing fluids under aerobic conditions in the event that they are accidentally released to surface waters and shallow soils. PMID:26037076

  12. Ipsilateral femoral shaft and vertical patella fracture: a case report

    PubMed Central

    Ozkan, Korhan; Eceviz, Engin; Sahin, Adem; Ugutmen, Ender

    2009-01-01

    Introduction A femoral shaft fracture with an ipsilateral patella fracture has been, to our knowledge, given only cursory attention in English-speaking literature. Case presentation A 15 year old male patient had hitten by a car to his motorcycle came to emergency room and he had been operated for his femoral shaft freacture and vertical patellar fracture which was iniatally missed. Conclusion To us it is vital to obtain CT scan of the patient’s knee if there is an ipsilateral femoral fracture with an ipsilateral knee effusion and a punction which reveals hematoma even in the absence of a fracture line seen in AP and lateral projections. PMID:19829933

  13. How intense quality control improves hydraulic fracturing

    SciTech Connect

    Ely, J.W. [Ely and Associates, Inc., Houston, TX (United States)

    1996-11-01

    Not unlike the subject of Forced Closure, Intense Quality Control is probably misnamed. What actually is discussed in this article is pilot testing of the fracturing fluids actually pumped at in-situ conditions of temperature and shear. Presented here is development of the need for onsite testing, equipment used, shear and viscosity curves from several jobs showing what went wrong that would otherwise not have been known, and a discussion of borate gel fluids.

  14. Hydraulic Fracture: multiscale processes and moving

    E-print Network

    Peirce, Anthony

    of Mathematics University of British Columbia WORKSHOP ON ROCK MECHANICS AND LOGISTICS IN MINING February 26 and physical processes Fracture Energy Breaking rock Leak-off Viscous energy loss #12;8 Scaling s olution time 2.58 hours BiCGS TAB-MG V(0,2) cycle : Total s olution time 0.27 hours BiCGS TAB-MG V(1

  15. Steamflood efficiency improvement through use of hydraulic fracturing technology - a simulation approach

    SciTech Connect

    Manrique, J.F.; Cole, H.E.; Frederick, A.F.

    1996-12-31

    We present the use of fracturing technology to accelerate performance and improve ultimate recovery in heavy oil reservoirs. The applicability and efficiency of this approach were investigated by means of numerical simulation. A fully implicit 3-13 thermal simulator was used to model the heat transfer efficiency and productivity enhancement when using this approach. Different scenarios were modeled for wells with horizontal and vertical fractures and for fractured horizontal wells with orthogonal, longitudinal and S-shaped fractures. This technology may be especially suitable for thinner reservoirs, dipping reservoirs and steam distillation drives. The {open_quote}heat plane source{close_quote} concept is presented in this paper to explain the advantages of fractured steam injectors for improvement of thermal recovery processes. During steam injection, heat convection and gravity effects become dominant in the near wellbore area causing excessive heat losses and poor recovery. We suggest an approach that will minimize convection override of the oil while creating a more efficient and stable steam drive. Numerical results suggest that production response of current steamflood operations can be improved by inclusion of hydraulic fractures. Additional advantages observed for fractured injectors suggested a modified injection schedule that improves productivity and steam allocation for neighboring projects. This results in a faster return of investment and substantial increase in cash flow during the early life of the project. The economic benefits were evaluated by incorporating the production response into an economic model that maximizes the Return of Investment and Net Present Value.

  16. Steamflood efficiency improvement through use of hydraulic fracturing technology - a simulation approach

    SciTech Connect

    Manrique, J.F.; Cole, H.E.; Frederick, A.F.

    1996-01-01

    We present the use of fracturing technology to accelerate performance and improve ultimate recovery in heavy oil reservoirs. The applicability and efficiency of this approach were investigated by means of numerical simulation. A fully implicit 3-13 thermal simulator was used to model the heat transfer efficiency and productivity enhancement when using this approach. Different scenarios were modeled for wells with horizontal and vertical fractures and for fractured horizontal wells with orthogonal, longitudinal and S-shaped fractures. This technology may be especially suitable for thinner reservoirs, dipping reservoirs and steam distillation drives. The [open quote]heat plane source[close quote] concept is presented in this paper to explain the advantages of fractured steam injectors for improvement of thermal recovery processes. During steam injection, heat convection and gravity effects become dominant in the near wellbore area causing excessive heat losses and poor recovery. We suggest an approach that will minimize convection override of the oil while creating a more efficient and stable steam drive. Numerical results suggest that production response of current steamflood operations can be improved by inclusion of hydraulic fractures. Additional advantages observed for fractured injectors suggested a modified injection schedule that improves productivity and steam allocation for neighboring projects. This results in a faster return of investment and substantial increase in cash flow during the early life of the project. The economic benefits were evaluated by incorporating the production response into an economic model that maximizes the Return of Investment and Net Present Value.

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

    SciTech Connect

    Laue, M.L.

    1997-11-21

    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.

  18. Numerical Simulation of Potential Groundwater Contaminant Pathways from Hydraulically Fractured Oil Shale in the Nevada Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Rybarski, S.; Pohll, G.; Pohlmann, K.; Plume, R.

    2014-12-01

    In recent years, hydraulic fracturing (fracking) has become an increasingly popular method for extraction of oil and natural gas from tight formations. Concerns have been raised over a number of environmental risks associated with fracking, including contamination of groundwater by fracking fluids, upwelling of deep subsurface brines, and methane migration. Given the potentially long time scale for contaminant transport associated with hydraulic fracturing, numerical modeling remains the best practice for risk assessment. Oil shale in the Humboldt basin of northeastern Nevada has now become a target for hydraulic fracturing operations. Analysis of regional and shallow groundwater flow is used to assess several potential migration pathways specific to the geology and hydrogeology of this basin. The model domain in all simulations is defined by the geologic structure of the basin as determined by deep oil and gas well bores and formation outcrops. Vertical transport of gaseous methane along a density gradient is simulated in TOUGH2, while fluid transport along faults and/or hydraulic fractures and lateral flow through more permeable units adjacent to the targeted shale are modeled in FEFLOW. Sensitivity analysis considers basin, fault, and hydraulic fracturing parameters, and results highlight key processes that control fracking fluid and methane migration and time scales under which it might occur.

  19. Mechanical stability of propped hydraulic fractures: A numerical study

    SciTech Connect

    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

    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.

  20. 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

    Cerveny, Vlastislav

    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

  1. Hydraulic Fracture: multiscale processes and moving

    E-print Network

    Peirce, Anthony

    model and physical processes Fracture Energy Breaking rock Leak-off Viscous energy loss #12;9 Scaling) CumulativeSolutionTime(hours) BiCGS TAB : Total s olution time 2.58 hours BiCGS TAB-MG V(0,2) cycle : Total s olution time 0.27 hours BiCGS TAB-MG V(1,2) cycle : Total s olution time 0.31 hours 1 1.5 2 2.5 3 3.5 4 0

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

    E-print Network

    Paris-Sud XI, Université de

    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

  3. Method for hydraulic fracture propagation in hydrocarbon-bearing formations

    Microsoft Academic Search

    M. D. Zoback; C. B. Raleigh

    1987-01-01

    A method is described of hydraulically fracturing a hydrocarbon-bearing strata in a hydrocarbon producing well comprising: providing a hydrocarbon-producing well having a hydrocarbon-bearing strata, a bounding non-producing strata overlying the hydrocarbon-bearing strata, and a bounding non-producing strata underlying the hydrocarbon-producing strata; determining the maximum principal compressive stress S⁠for the hydrocarbon-bearing strata, the overlying bounding non-producing strata, and the underlying

  4. An investigation of productivity increases from hydraulic fracturing treatments 

    E-print Network

    Boriskie, Robert Joe

    1963-01-01

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

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

    E-print Network

    Jackson, Robert B.

    New Tracers Identify Hydraulic Fracturing Fluids and Accidental Releases from Oil and Gas fingerprints of fluids that return to the surface after high volume hydraulic fracturing of unconventional oil elemental and isotopic signatures (B/Cl, Li/Cl, 11 B, and 7 Li) useful for characterizing hydraulic

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

    E-print Network

    Peirce, Anthony

    Implicit level set schemes for modeling hydraulic fractures using the XFEM Elizaveta Gordeliy Copyright Ó 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

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

    E-print Network

    Santos, Juan

    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

  8. Active Monitoring of Hydraulic Fractures Using Slow Waves in the Fracture and Tube Waves in the Borehole

    Microsoft Academic Search

    G. A. Maximov; A. Derov; D. Lesonen; B. Kashtan; M. Lazarkov

    2010-01-01

    Propagating tube waves carry an important information about properties of surrounding medium and, in particular, about cracks or fractures intersecting the well. Knowledge of fracture geometry and dimensions has a critical importance for hydraulic fracturing process. The interaction of tube wave with a fracture is usually considered in the limit of infinite plane fluid layer (Beydoun et al., 1985; Tang

  9. Multiple hydraulic fracture stimulation in a deep, horizontal tight-gas well

    SciTech Connect

    Abou-Sayed, I.S. [Mobil E and P Technical Center, Dallas, TX (United States); Schueler, S.K.; Ehrl, E. [Mobil Erdgas-Erdoel GmbH, Celle (Germany); Hendriks, W.P.

    1996-02-01

    This paper outlines the stimulation program used for successful completion of the 15,687-ft total-vertical-depth (TVD) horizontal well, Well Soehlinger Z10, in the tight Rotliegendes sandstone, on-shore Germany. The program included the breakdown multiple-rate injectivity test, use of proppant erosion stages to reduce near-well-bore restrictions, and minifracture data analysis. Use of open annulus to analyze the stimulation treatment and to modify the design is also covered. Considerations and experiments behind the design and execution of this horizontal well stimulation with hydraulic fractures perpendicular to the wellbore are presented and discussed.

  10. Asymptotic Analysis of Cross-Hole Hydraulic Tests in Fractured Granite

    E-print Network

    Daniels, Jeffrey J.

    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

  11. Dynamic Fluid Loss in Hydraulic Fracturing Under Realistic Shear Conditions in High-Permeability Rocks

    Microsoft Academic Search

    R. C. Navarrete; K. E. Cawiezel; V. G. Constien

    1996-01-01

    A study of the dynamic fluid loss of hydraulic fracturing fluids under realistic shear conditions is presented. During a hydraulic fracturing treatment, a polymeric solution is pumped under pressure down the well to create and propagate a fracture. Part of the fluid leaks into the rock formation, leaving a skin layer of polymer or polymer filter cake, at the rock

  12. Seismic imaging using microearthquakes induced by hydraulic fracturing

    SciTech Connect

    Block, L.V.; Cheng, C.H. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Earth, Atmospheric, and Planetary Sciences; Fehler, M.C.; Phillips, W.S. [Los Alamos National Lab., NM (United States)

    1994-01-01

    Seismic imaging using microearthquakes induced by hydraulic fracturing produces a three-dimensional (3-D), S-wave velocity model of the fractured zone, improves the calculated locations of the microearthquakes, and may lead to better estimates of fracture-plane orientations, fracture density, and water flow paths. Such information is important for predicting the amount of heat energy that may be extracted from geothermal reservoir. A fractured zone was created at the Los Alamos Hot Dry Rock Reservoir in north-central New Mexico within otherwise impermeable basement rock by injecting 21,000 m{sup 3} of water into a borehole under high pressure at a depth of 3.5 km. Induced microearthquakes were observed using four borehole seismometers. The P-wave and S-wave arrival times have been inverted to find the 3-D velocity structures and the microearthquake locations and origin times. The inversion was implemented using the separation of parameters technique, and constraints were incorporated to require smooth velocity structures and to restrict the velocities within the fractured region to be less than or equal to the velocities of the unfractured basement rock.

  13. Hydraulic fracturing design and evaluation: A case history

    SciTech Connect

    Al-Khatib, A.M.; King, A.R.; Wilson, M.S.

    1984-04-01

    A unique method utilizing fluid entry surveys has been developed to improve fracture treatment designs at the Lost Hills Oil Field. Fluid entry surveys were conducted on thirty-two hydraulicly fractured wells in three different sections of the Lost Hills Oil Field. The surveys were analyzed to identify intervals of the completed zone contributing to flow (Contribution Ratio, C /SUB R/) and to determine intervals of high water production. Data from this type of analysis were then used to develop a correlation between the total thickness of the perforated/fractured zone and the fraction of that zone contributing to fluid flow (C /SUB R/). Considering this relationship as a potential design criteria, many fracture treatments were logged and evaluated. In conjunction with the aforementioned relationship, empirical correlations relating to perforation size and density, friction pressure losses and surface treatment rates were then used to modify the fracture treatment designs. Through the use of these correlations, optimum interval thickness to be fractured in one stage can be determined. Improved multi stage treatment design has resulted in greater production increases.

  14. Simulations of pressure fluctuations and acoustic emission in hydraulic fracturing

    SciTech Connect

    Tzschichholz, F.; Herrmann, H.J. [Division of Physics and Mechanics, School of Technology, Aristotele University of Thessaloniki, 54006 Thessaloniki (Greece)] [Division of Physics and Mechanics, School of Technology, Aristotele University of Thessaloniki, 54006 Thessaloniki (Greece); [HLRZ, Kernforschungsanlage Juelich, Postfach 1913, 5170 Juelich (Germany); [P.M.M.H. (CNRS, URA 857), Ecole Superieuree de Physique et de Chimie Industrielle de la Ville de Paris, 10 rue Vauquelin, 75231 Paris Cedex 05 (France)

    1995-03-01

    We consider a two-dimensional lattice model to describe the opening of a crack in hydraulic fracturing. In particular, we consider that the material only breaks under tension and the fluid has no pressure drop inside the crack. For the case in which the material is completely homogeneous (no disorder), we present results for pressure and elastic energy as a function of time and compare our findings with some analytic results from continuum fracture mechanics. Then we investigate fracture processes in strongly heterogeneous cohesive environments. We determine the cumulative probability distribution for breaking events of a given energetical magnitude (acoustic emission). Further, we estimate the probability distribution of emission free time intervals. Finally, we determine the fractal dimension(s) of the cracks.

  15. Are sills really elastic hydraulic fractures?

    NASA Astrophysics Data System (ADS)

    Spacapan, Juán B.; Galland, Olivier; Leanza, Héctor A.; Planke, Sverre

    2015-04-01

    Seismic reflection data and field observations have over the past few decades revealed the presence of voluminous igneous sill complexes in sedimentary basins worldwide. The implications of sill emplacement in sedimentary basins are numerous: they trigger maturation of organic-rich formations, they produce large quantities of greenhouse gases that trigger dramatic climate change and mass extinctions, and they produce small- and large-scale structures that affect fluid flow. Therefore, a proper understanding of their emplacement mechanism is essential. Most models of sill and laccolith emplacement account for purely elastic host rock, and their propagation mechanism is dominantly assumed to be according to the Linear Elastic Fracture Mechanics (LEFM) theory. Recent field and seismic observations, however, demonstrated that part, if not all, sill- and laccolith-induced deformation is accommodated by inelastic deformation, strongly questioning the relevance of the LEFM theory applied for igneous intrusions. In this contribution, we present detailed structural observations from spectacularly well-exposed sills in the northern Neuquén Basin, Argentina. We studied a 50-m outcrop that exhibits very clearly three sills of different sizes, the shapes of their tips, and the associated structures in their sedimentary host rock, i.e. the calcareous pelites of the organic-rich Vaca Muerta Fm. This formation is adequate to map the structures at the outcrop scale, as it consists in fine layers of mudstone inter-bedded with weak shale, such that it is possible to map each layer along the entire outcrop. Detailed structural mapping evidence that the sedimentary layers have not been opened, i.e. pushed away by the emplacement of the sills, as expected from the LEFM theory. Indeed, some of the sedimentary layers are not present at the location of the sills, but they appear duplicated several times ahead of the tips of the three observed sills; the relative movements between the duplicated segments are clearly associated with shortening. Therefore, our field observations show that the host rock is pushed and shortened ahead of the sill tips, in total contradiction with the extensional features predicted by the LEFM theory. The structures described above strongly suggest instead that these sills were emplaced according to the viscous indenter model, in good agreement with recent laboratory models (Abdelmalak et al., 2012). These detailed observations strongly question the geological relevance of the LEFM theory applied to igneous sheet intrusions, and call for more field observations to better constrain the dynamics of sill and dyke emplacement mechanisms. Abdelmalak, M.M., Mourgues, R., Galland, O., Bureau, D., 2012. Fracture mode analysis and related surface deformation during dyke intrusion: Results from 2D experimental modelling. Earth Planet. Sci. Lett. 359-360, 93-105.

  16. Application of a 3D hydraulic-fracturing simulator for design of acid-fracturing treatments

    SciTech Connect

    Morgenthaler, L.N. (Shell Development Co., Houston, TX (United States))

    1994-02-01

    Field experience during 1989--90 shows that application of a 3D hydraulic-fracturing simulator increases success of acid-fracturing well treatments. Fracture extension can be limited to the oil-bearing pay, maximum lateral extension can be realized within the height constraint, and acid/rock contact time can be increased by a factor of between 3 and 30. Oil-production response can be improved over other stimulation designs while water-production response can be limited. These methods have been applied in mature waterfloods of the Permian Basin and Cedar Creek anticline.

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

    E-print Network

    Marpaung, Fivman

    2009-05-15

    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...

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

    E-print Network

    Marpaung, Fivman

    2008-10-10

    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...

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

    E-print Network

    Marpaung, Fivman

    2009-05-15

    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...

  20. Computer simulation of hydraulic fracturing in shales-influences on primary migration

    SciTech Connect

    Ozkaya, I.

    1984-05-01

    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 paper describes an attempt to simulate the process of hydraulic fracturing during burial and compaction of a shale layer by use of an elementary model. One objective is to investigate the role of various factors in hydraulic tension fracturing of shales in a tectonically relaxed area. Another objective is to see whether hydraulic fractures form at depths of oil generation.

  1. Anaerobic Biodegradation of Ethylene Glycol within Hydraulic Fracturing Fluid

    NASA Astrophysics Data System (ADS)

    Heyob, K. M.; Mouser, P. J.

    2014-12-01

    Ethylene glycol (EG) is a commonly used organic additive in hydraulic fracturing fluids used for shale gas recovery. Under aerobic conditions, this compound readily biodegrades to acetate and CO2 or is oxidized through the glycerate pathway. In the absence of oxygen, organisms within genera Desulfovibrio, Acetobacterium, and others can transform EG to acetaldehyde, a flammable and suspected carcinogenic compound. Acetaldehyde can then be enzymatically degraded to ethanol or acetate and CO2. However, little is known on how EG degrades in the presence of other organic additives, particularly under anaerobic conditions representative of deep groundwater aquifers. To better understand the fate and attenuation of glycols within hydraulic fracturing fluids we are assessing their biodegradation potential and pathways in batch anaerobic microcosm treatments. Crushed Berea sandstone was inoculated with groundwater and incubated with either EG or a synthetic fracturing fluid (SFF) containing EG formulations. We tracked changes in dissolved organic carbon (DOC), EG, and its transformation products over several months. Approximately 41% of bulk DOC in SFF is degraded within 21 days, with 58% DOC still remaining after 63 days. By comparison, this same SFF degrades by 70% within 25 days when inoculated with sediment-groundwater microbial communities, suggesting that bulk DOC degradation occurs at a slower rate and to a lesser extent with bedrock. Aerobic biodegradation of EG occurs rapidly (3-7 days); however anaerobic degradation of EG is much slower, requiring several weeks for substantial DOC loss to be observed. Ongoing experiments are tracking the degradation pathways of EG alone and in the presence of SFF, with preliminary data showing incomplete glycol transformation within the complex hydraulic fracturing fluid mixture. This research will help to elucidate rates, processes, and pathways for EG biodegradation and identify key microbial taxa involved in its degradation.

  2. Hydraulic fracturing: insights from field, lab, and numerical studies

    NASA Astrophysics Data System (ADS)

    Walsh, S. D.; Johnson, S.; Fu, P.; Settgast, R. R.

    2011-12-01

    Hydraulic fracturing has become an increasingly important technique in stimulating reservoirs for gas, oil, and geothermal energy production. In use commercially since the 1950's, the technique has been widely lauded, when combined with other techniques, for enabling the development of shale gas resources in the United States, providing a valuable and extensive source of domestic energy. However, the technique has also drawn a degree of notoriety from high-profile incidents involving contamination of drinking water associated with gas extraction operations in the Marcellus shale region. This work highlights some of the insights on the behavior of subsurface hydraulic fracturing operations that have been derived from field and laboratory observations as well as from numerical simulations. The sensitivity of fracture extent and orientation to parameters such as matrix material heterogeneity, presence and distribution of discontinuities, and stress orientation is of particular interest, and we discuss this in the context of knowledge derived from both observation and simulation. The limitations of these studies will also be addressed in terms of resolution, uncertainty, and assumptions as well as the balance of fidelity to cost, both in computation time (for numerical studies) and equipment / operation cost (for observational studies). We also identify a number of current knowledge gaps and propose alternatives for addressing those gaps. We especially focus on the role of numerical studies for elucidating key concepts and system sensitivities. The problem is inherently multi-scale in both space and time as well as highly coupled hydromechanically, and, in several applications, thermally as well. We will summarize the developments to date in analyzing these systems and present an approach for advancing the capabilities of our models in the short- to long-term and how these advances can help provide solutions to reduce risk and improve efficiency of hydraulic fracturing operations. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  3. Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, October 1--December 31, 1996

    SciTech Connect

    Laue, M.L.

    1997-02-13

    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 Unites States Department of Energy granted approval of the continuation application to implement Budget Period Two effective November 21, 1996. The only Budget Period One activities for the quarter involved project administration. Budget Period Two activities were initiated with the development of a drilling program for the high-angle slant well. The well was spud on December 4, 1996 and was drilling at 10,830 ft in the vertical section of the hole as of the end of the month.

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

    SciTech Connect

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

    1996-12-31

    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.

  5. The Geometry of Shallow Sills and Hydraulic Fractures

    NASA Astrophysics Data System (ADS)

    Bunger, A. P.; Jeffrey, R. G.; Detournay, E.

    2005-12-01

    We have studied in laboratory experiments the tendency of fluid-driven shallow subsurface fractures, such as magmatic sills or hydraulic fractures, to curve and form concave upward bowl-shaped structures. We consider the particular case of a crack driven by a Newtonian fluid that is: 1) initially radially-symmetric about the fluid-injection point and 2) initially parallel to the traction-free surface of a specimen subjected to a uniform normal compressive stress (?r) acting parallel to the free-surface. The results indicate that these fractures curve and the curving becomes strong when the radius is on the same order as the initial depth. The fractures eventually daylight, or erupt. The curving arises because of the mechanical/geometric asymmetry induced by the interaction of the fracture with the surface and in spite of the fact that the least compressive far-field stress direction is perpendicular to the surface. The bowl-shaped fractures are not self-similar structures that scale by the initial depth, but rather the shape of the bowl is controlled by a dimensionless parameter which compares the magnitude of ?r with a characteristic fracture-induced stress given by the fracture toughness (KIc) divided by the square-root of the initial depth (H). In particular, the larger the ratio ?r ?H/KIc, the flatter the bowl-shaped fracture will be and furthermore, two fractures will have approximately the same shape up to a re-scaling by H provided that the ratio ?r ?H/KIc is the same for the two cases. The bowl-shape is reasonably insensitive to the particulars of the internal pressure distribution, and therefore the geometric similarity dependence on ?r ?H/KIc suggests that its value at the time of fracture growth may be ascertained from the final fracture shape. It may also be concluded that propagation parallel to the surface corresponds to the limit of ?r ?H/KIc going to infinity. These near-surface curving fractures do not always grow in a radially-symmetric manner. Rather, at some point, as the fracture grows larger, propagation favors a given direction to the detriment of the others resulting in a fracture that is egg-shaped in plan view. Hence, eruption at the surface occurs along only a small portion of the fracture's circumference (the pointed end of the egg) and the region of the fracture or sill immediately adjacent to the eruption point appears as a relatively short dike (compared with the fracture radius) with oblique to sub-horizontal intersection with the surface. Experimental results suggest that the circular-to-egg-shape transition occurs earlier in the fracture's life and results in more elongated egg-shapes when the relative importance of viscous dissipation, which may be quantified by a dimensionless ratio of the controlling parameters, takes on smaller values. Hence, the most elongated egg-shapes correspond to the uniform fluid pressure case that arises in the limit when viscous dissipation vanishes.

  6. Analyses of an Elmworth hydraulic fracture in Alberta

    SciTech Connect

    Wyman, R.E.; Holditch, S.A.; Randolph, P.L.

    1980-09-01

    The Elmworth gas field in Alberta's Deep basin could hold more than 400 trillion CF of recoverable gas reserves. To obtain more information on the economics and technology required to produce this gas, Canadian engineers performed a large (700-ft) hydraulic foam fracture over the Cretaceous Falher Zones A and B in a tight sand having an in situ permeability of about 1 microdarcy. The sand produced at rates close to those predicted: after each perforation was broken down, the flow was 21,000 CF/day; after the minifracture (9450 lbm of sand), 35,000 CF/day; and following the main fracture (5.65 million CF of nitrogen injecting 250,000 lbm of sand), 1 million CF/day, which declined within 23 days to 300,000 CF/day. Although at current gas prices, such sands can not be economically produced, model runs indicate that dual completions with hydraulic fractures of at least 700 ft would be profitable at a netback to the producer of $3.50/1000 CF, assuming a 10%/yr gas-price increase and a 7%/yr operating expense.

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

    E-print Network

    McKenzie, Jeffrey M.

    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

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

    E-print Network

    Pongthunya, Potcharaporn

    2009-06-02

    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...

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

    E-print Network

    Zarrin, Tahira

    2014-04-17

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

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

    E-print Network

    Kamenov, Anton

    2013-04-11

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

  11. The impact of gravity segregation on multiphase non-Darcy flow in hydraulically fractured gas wells 

    E-print Network

    Dickins, Mark Ian

    2008-10-10

    Multiphase and non-Darcy flow effects in hydraulically fractured gas wells reduce effective fracture conductivity. Typical proppant pack laboratory experiments are oriented in such a way such that phase segregation is not possible, which results...

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

    E-print Network

    Pongthunya, Potcharaporn

    2009-06-02

    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...

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

    E-print Network

    Zarrin, Tahira

    2014-04-17

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

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

    E-print Network

    Kamenov, Anton

    2013-04-11

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

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

    Microsoft Academic Search

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

    1991-01-01

    Hydraulic fracturing is a widely-used well completion technique for enhancing the recovery of gas and oil in low-permeability formations. Hydraulic fracturing consists of pumping fluids into a well under high pressure (1000--5000 psi) to wedge-open and extend a fracture into the producing formation. The fracture acts as a conduit for gas and oil to flow back to the well, significantly

  16. Advances in hydraulic fracturing technology in the antrim shale. Topical report, July 1994-December 1996

    SciTech Connect

    Frantz, J.H.; Hopkins, C.W.

    1996-12-01

    The primary objectives of this study were to evaluate hydraulic fracture geometry in the naturally-fractured Antrim Shale. As part of this research, stress profiling and numerous hydraulic fracture experiments were performed. The research project performed field-based studies to better understand hyraulic fracture growth in the Antrim. This understanding will make it possible to verify the optimal stimulation treatment for operators to use during the next five years. The research results succeeded in determining how hydraulic fractures grow in the Antrim Shale formation.

  17. Multipole moment decomposition for imaging hydraulic fractures from remote elastostatic data

    Microsoft Academic Search

    B. Lecampion; A. Peirce

    2007-01-01

    Hydraulic fracturing involves the propagation of a fracture in brittle rock by the intrusion of a high pressure viscous fluid. There is considerable interest in identifying characteristics of these evolving underground fractures via the passive monitoring of remote elastostatic deformations. In this paper, we present a far-field multipole expansion procedure to identify the harmonic moments of the fracture. The harmonic

  18. The evolution of an applied hydraulic fracture project, Frontier Formation Moxa Arch, Wyoming

    SciTech Connect

    Harkrider, J.D.; Aud, W.W.; Cipolla, C.L.; Hansen, J.T.

    1994-12-31

    This paper demonstrates a methodical approach in the implementation of current hydraulic fracturing technologies. Specific examples illustrating the evolution of a consistent reservoir/hydraulic fracturing interpretation are presented in a case history of three GRI-Industry Technology Transfer wells. Detailed modeling of these project wells provided an overall reservoir and hydraulic fracture description that was consistent with respect to all observations. Based on identification of the fracturing mechanisms occurring, the second and third project wells show the capabilities of real-time diagnostics in the implementation of hydraulic fracture treatments. By optimizing the pad volume and fluid integrity to avoid premature screenouts, significant cost savings and improved proppant placement were achieved. The production and pressure build-up response in the first project well verifies the overall interpretation of the reservoir/hydraulic fracture model and provides the basis for eliminating the use of moderate strength/higher cost proppant over sand in low permeability/higher closure stress environments.

  19. Modelling of of hydraulic fractures trajectories in inhomogeneous stress field

    NASA Astrophysics Data System (ADS)

    Andreev, A. A.; Galybin, A.

    2013-05-01

    The paper examines an actual problem of oil and gas production -- modelling of the hydro-fracture trajectories depending on ihomogeneous distributions of pore pressure. The results could serve for improvement of the design of hydraulic fracturing in the oil/gas fields. The methods of the plane elasticity theory and fracture mechanics are employed. It is assumed, that in addition to the homogeneous field of natural stress the reservoir is also subjected to additional stresses caused by technological reasons, which makes the total stress field to be inhomogeneous. Therefore, the objective is to model a curvilinear crack path in an elastic inhomogeneous-loaded plane depending on the different mechanical parameters that control the stress state of the reservoir. For the simulation of the trajectory of a crack the method of boundary integral equation is used. The algorithms of step-by-step determination of the crack's trajectory development using the criterion of maximum tensile stresses at the end of the cracks have been developed. For the numerical realization of the solution we used a special modification of the method of mechanical quadratures providing effective and fast solution of the corresponding system of singular integral equation. The solution for the hydro-fracture path have been simulated for the case of inhomogeneous stress field due to presence of injection well for several physical models.

  20. Effective hydraulic parameters for steady state vertical flow in heterogeneous soils

    E-print Network

    Mohanty, Binayak P.

    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

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

    E-print Network

    Min, Kyoung

    2013-07-16

    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 ...

  2. Economic reocvery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, July 1 - September 30, 1996

    SciTech Connect

    Niemeyer, B.L.

    1996-10-01

    This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbitide complex through the use of hydraulically- fractured, horizontal, or high-angle wells. The combination of 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 by fracturing an existing test well. Fracture azimuth will be predicted, in part, by passive seismic monitoring from an offset well during fracture stimulation of the test well. The fine-grid reservoir simulation of the northeast fan-margin region of the Yowlumne field was completed during third quarter 1996. A variety of development alternatives were investigated aimed at optimizing project economics. Model forecasts, compared slant well performance to more conventional development options and quantified rate impacts due to changes in well location, orientation, and completion technique. Project economics were then updated with the production forecasts from the simulation model.

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

    SciTech Connect

    Laue, M.L.

    1997-08-31

    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 and completion operations are in progress. Upon initial review of log data, two hydraulic fracture treatments were planned. However, the probability of the lower frac growing into thick sands previously swept by waterflood has called for additional information to be obtained prior to proceeding with hydraulic fracture treatments. Should permeabilities prove to be as favorable as some data indicate, produced water volumes could be excessively high. Prior to pumping the first frac, the well will be perforated and produced from lower pay intervals. These perfs will not impact future frac work. Rate data and pressure transient analysis will dictate the need for the lower frac.

  4. Examination of a cored hydraulic fracture in a deep gas well

    SciTech Connect

    Warpinski, N.R.; Lorenz, J.C. (Sandia National Lab., Albuquerque, NM (United States)); Branagan, P.T.; Myal, F.R. (CER Corp., Las Vegas, NV (United States)); Gall, B.L. (NIPER, Bartlesville, OK (United States))

    1993-08-01

    A hydraulic fracture stimulation conducted during 1983--84 in nonmarine, deltaic, Mesaverde strata at 7,100 ft [2,164 m] was cored in a deviated well in 1990. The observed fracture consists of two fracture intervals, both containing multiple fracture strands (30 and 8, respectively), abundant gel residue on the fracture surfaces, and many other complexities. Slant Hole Completion Test (SHCT). These new results suggest that hydraulic fracturing is a much more complex process than is generally accepted. 55 refs., 9 figs., 1 tab.

  5. Oil and Gas CDT Quantification of hydraulic fracturing induced seismic risks

    E-print Network

    Henderson, Gideon

    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

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

    Microsoft Academic Search

    S. H. Advani; J. K. Lee

    1984-01-01

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

  7. Interaction of proppants with crack formation and propagation in hydraulic fracturing

    Microsoft Academic Search

    S. L. McHugh; P. E. Senseny; D. D. Keough; A. L. Florence

    1979-01-01

    Well productivity often can be increased by repeated hydraulic fracturing. Repeated flow cycling also has been shown to increase productivity. The increased productivity suggests that a predictive capability for treating specific wells could be developed if controlling parameters and their interactions in the flow-cycle treatment process were better understood. Although the primary role of the proppant in hydraulic fracturing is

  8. Compilation of Physicochemical and Toxicological Information About Hydraulic Fracturing-Related Chemicals (Draft Database)

    EPA Science Inventory

    The purpose of this product is to make accessible the information about the 1,173 hydraulic fracturing-related chemicals that were listed in the external review draft of the Hydraulic Fracturing Drinking Water Assessment that was released recently. The product consists of a serie...

  9. 78 FR 34611 - Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ...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...

  10. Pressure responses from induced hydraulic fractures in adjacent wells within a petroleum reservoir: an experiment

    Microsoft Academic Search

    C. A. Komar; L. Z. Shuck

    1974-01-01

    Pressure responses from induced hydraulic fractures in five adjacent oil wells were monitored by 40 wells within the petroleum reservoir in northern Pennsylvania. The multisensor array of pressure transducers were arranged in 4 x 4 five-spot patterns and located a considerable distance away from the stimulated wells. Dynamic pressure behavior from four hydraulic fracturing treatments was observed in three of

  11. Coordinated studies in support of hydraulic fracturing of coalbed methane. Final report, July 1990-May 1995

    SciTech Connect

    Penny, G.S.; Conway, M.W.

    1996-02-01

    The primary objective of this project is to provide laboratory data that is pertinent to designing hydraulic fracturing treatments for coalbed methane. Coal fluid interactions studies, fracture conductivity, fluid leak-off through cleats, rheology, and proppant transport are designed to respresent Black Warrior and San Juan treatments. A second objective is to apply the information learned in laboratory testing to actual hydraulic fracturing treatments in order to improve results. A final objective is to review methods currently used to catalog well performance following hydraulic fracturing for the purpose of placing the data in a useable database that can be accessed by users to determine the success of various treatment scenarios.

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

    SciTech Connect

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

    1981-04-01

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

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

    E-print Network

    Zhan, Hongbin

    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 conditions is presented. Solutions for hydraulic heads in both leaky confined and water table aquifers

  14. Microcomputer Analysis of Hydraulic Fracture Behavior With a Pseudo-Three-Dimensional Simulator

    Microsoft Academic Search

    R. H. Morales; A. S. Abou-Sayed

    1989-01-01

    The theory describing a pseudo-three-dimensional (pseudo-3D) hydraulic fracturing model that solves the coupled fluid-flow and elastic-rock-deformation problem associated with a fracture propagating into a zone composed of three or more layers is presented. The fracture is initiated in the center layer. Fracture growth is formulated from the critical-stress-intensity-factor criterion, and fracture width is obtained from plane-strain elasticity solutions. Fluid fronts

  15. Direct Imaging of Natural Fractures and Stress Compartments Stimulated by Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Lacazette, A.; Vermilye, J. M.

    2014-12-01

    This contribution will present results from passive seismic studies of hydraulic fracture treatments in North American and Asian basins. One of the key data types is a comparatively new surface-based seismic imaging product - "Tomographic Fracture Images®" (TFI®). The procedure is an extension of Seismic Emission Tomography (SET), which is well-established and widely used. Conventional microseismic results - microearthquake hypocenter locations, magnitudes, and focal mechanism solutions - are also obtained from the data via a branch of the processing workflow. TFI is accomplished by summing the individual time steps in a multidimensional SET hypervolume over extended periods of time, such as an entire frac stage. The dimensions of a SET hypervolume are the X, Y, and Z coordinates of the voxels, the time step (typically on the order of 100 milliseconds), and the seismic activity value. The resulting summed volume is skeletonized to produce images of the main fracture surfaces, which are known to occupy the maximum activity surfaces of the high activity clouds from theory, field studies, and experiments. The orientation vs. area of the resulting TFIs can be analyzed in detail and compared with independent data sets such as volumetric structural attributes from reflection seismic data and borehole fracture data. We find that the primary effect of hydraulic fracturing is to stimulate preexisting natural fracture networks and faults. The combination of TFIs with hypocenter distributions and microearthquake focal mechanisms provides detailed information on subsurface stress compartmentalization. Faults are directly imaged which allows discrimination of fault planes from auxiliary planes of focal mechanism solutions. Examples that will be shown include simultaneous movement on a thrust fault and tear fault and examples of radically different stress compartments (e.g. extensional vs. wrench faulting) stimulated during a single hydraulic fracture treatment. The figure shows a TFI of a single frac stage in the Eagle Ford FmFm that is unusually symmetrical and smooth near the perforations. Color shows intensity of cumulative seismic activity (red = high, violet = low). Note that the energy decreases and the complexity increases as the frac quenches in the natural fracture system.

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

    E-print Network

    Peirce, Anthony

    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

  17. 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

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

    E-print Network

    Peirce, Anthony

    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

  19. 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

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

    E-print Network

    Dunham, Eric M.

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

  1. 77 FR 36273 - Public Meeting on Draft Permitting Guidance for Oil and Gas Hydraulic Fracturing Activities Using...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-18

    ...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...

  2. Hydraulic fracture stimulation of highly permeable formations: The effect of critical fracture parameters on oilwell production and pressure

    SciTech Connect

    Mathur, A.K.; Ning, X.; Marcinew, R.B. [and others

    1995-12-31

    Hydraulic fracturing of moderate to high-permeability reservoirs with short, highly conductive fractures is a technique often applied to improve well productivity through penetration beyond near wellbore damage. This paper investigates the effect of important fracture parameters (e.g., fracture half-length, fracture conductivity, and fracture-face damage) on the short-term behavior and long-term productivity of the well. The degree and extent of near wellbore damage, in addition to the fracture parameters, are varied in the sensitivity analysis. A case study from the Gulf Coast addresses the effect of these important parameters on the well response. It is evident the length and conductivity of a created hydraulic fracture have an important effect on the poststimulation performance of a well. Some of these fractures may be damaged. Damage to the proppant-pack has considerable effects, reducing the fracture conductivity. Generally fracture-face damage caused by fluid and polymer leakoff does not significantly alter long-term production, assuming the permanent reduction of absolute permeability is low (less than 90%) and provided the fracture bypasses the radial 1damage zone in the formation. When the fracture face damage is high (greater than 90%), early time well response is significantly impaired by the fracturing fluid cleanup process. This has implications on the timing of poststimulation pressure transient analyses. The modeled behavior and recommendations for the design of such tests are presented.

  3. Characterization of a remotely intersected set of hydraulic fractures: Results of intersection well no. 1-B, GRI/DOE multi-site project

    SciTech Connect

    Branagan, P.T.; Peterson, R.E.; Warpinski, N.R.; Wright, T.B.

    1996-12-31

    A deviated observation or {open_quotes}intersection{close_quotes} well (IW 1-B) was drilled, cored, logged and tested through an area in a fluvial sandstone reservoir that had previously been hydraulically fractured. The point of intersection with the fractured interval was located 126 ft from the fracture well along one wing of the fracture(s) at a measured depth of 4,675 ft. Direct observations from core and borehole imagery logs in IW 1-B indicate that a total of 11 far-field vertical fractures were created. Clustered in a narrow 2.6-ft-wide interval, these 11 fractures are the direct result of 6 experimental fracture treatments executed in the distant frac well over a 4-month period. Diagnostic data acquired through IW I-B included direct core observations and measurements, borehole log imagery, gamma ray (GR) tracer identification, well-to-well pressure transient and fracture conductivity tests, and production logging surveys. The explicit intent in the emplacement of IW 1-B was to provide direct observations and information to characterize the hydraulic fracture(s) in support of a remote-sensing fracture diagnostic program that included microseismic monitoring and inclinometer measurements.

  4. Development of a generalized hydraulic fracture model: (Annual report) for the period November 1, 1985-October 31, 1986

    SciTech Connect

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

    1986-10-01

    The research tasks and accomplishments reported here represent a major contribution towards the rational development of a comprehensive simulator for hydraulic fracture processes. In particular, formulations and results from one-dimensional and advanced finite element simulations are presented. The developed model yields reasonable comparisons with published results on fracture length, height, and width for reservoirs with symmetric and unsymmetric in situ stress distributions. Problems associated with symmetric material property contrasts and vertical height penetration criteria are also detailed. The in situ stress analysis program can be used as a predictive tool for examining principal stress variations in reservoirs. Subsequent Mohr-Coulomb-Griffith failure analyses can identify potential naturally fractured regions and the orientations of these tectonically relaxed fracture systems. The fundamental solutions for the penny-shaped and elliptical crack models provide an economical framework for conducting parametric-sensitivity design studies. In addition, the validation of sophisticated numerical codes is facilitated. The non-Newtonian fracture fluid leak-off investigations furnish basic insight on the role of the power law exponent of pseudo-plastic type fluids. The inclusion of these non-Newtonian characteristics in the governing mass conservation equation is warranted since the leak-off expression is substantially modified. Finally, the judicious coupling of the induced hydraulic fracture geometry with a compatible reservoir model represents a logical step towards an integrated systems approach for optimum resource extraction. 11 refs., 2 figs., 2 tabs.

  5. Using the Semi-Circular Bending Test to Investigate the Interaction Between Hydraulic and Natural Fractures

    NASA Astrophysics Data System (ADS)

    Wang, W.; Olson, J. E.; Prodanovic, M.

    2014-12-01

    Micro-seismic data shows that hydraulic fracture propagation is a complex process. When hydraulic fractures interact with pre-existing natural fractures, it can result in a complex fracture network. The interaction depends on in-situ stresses, rock and natural fracture mechanical properties, approach angle and hydraulic fracture treatment parameters. Most simulation studies treat natural fractures as frictional interfaces with cohesive properties. However, from core observation, partially cemented and fully cemented natural fractures are widely present and it is not clear that whether they fit the common description or not. In this study, semi-circular bending experiments are utilized to examine the fracture propagation paths. Synthetic hydrostone samples with embedded inclusions of different mechanical properties are used to mimic rock and cemented natural fractures. Simulation results are generated using finite element software ABAQUS. The extended finite element method (XFEM) capability of ABAQUS allows the fracture initiation and propagation along a solution dependent path without the need for re-meshing. The simulation results are used to explain the experimental observations. In a series of experiment and modeling work, we assess the influence of the fracture approach angle, inclusion strength, and inclusion thickness on fracture propagation. Current results indicate the fracture propagation direction is strongly influenced by pre-existing inclusions. The propagating fractures tend to cross the inclusion when the approach angle is high and divert into the inclusion when the approach angle is low. The crossing surface is thus not a clean cut, but with a jog distance that depends on the inclusion thickness and approach angle. Results imply that if hydraulic fractures have lower approach angles to pre-existing natural fractures, the ultimate fracture network is going to have higher complexity. The thickness of natural fractures can also add to the complexity.

  6. Economic recovery of oil trapped at fan margins using high-angle wells and multiple hydraulic fractures. [Quarterly report], January 1--March 31, 1996

    SciTech Connect

    Niemeyer, B.L.

    1996-04-29

    This project attempts to demonstrate the effectiveness of exploiting thin, layered, low-energy, deposits at the distal margin of a prograding turbidite complex through use of fractured horizontal or high-angle wells. The combination of hydraulic fracturing and horizontal drilling will allow greater pay exposure than 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 hydraulic fracture treatments will be determined by fracturing an existing test well. Fracture azimuth will be predicted, in part, by passive seismic monitoring from an offset well during fracture stimulation of the test wellbore. An existing vertical well in the Yowlumne Field, Kern Co., California was hydraulically fractured. Microseismic and pressure data collected from this work are being used to predict fracture geometry and azimuth for future treatments in the proposed high-angle well. A detailed reservoir characterization of the field demonstration site is complete. This work include interpretation of a 3-D seismic survey, analysis of all available well logs, description of three whole cores, petrographic analysis of thin sections and incorporation of pressure and production data. A partial-field fine-grid model base on the reservoir characterization has been constructed and initialized. Efforts to history match the model to actual production and pressure data are underway.

  7. Active and passive acoustic imaging inside a large-scale polyaxial hydraulic fracture test

    SciTech Connect

    Glaser, S.D.; Dudley, J.W. II; Shlyapobersky, J.

    1999-07-01

    An automated laboratory hydraulic fracture experiment has been assembled to determine what rock and treatment parameters are crucial to improving the efficiency and effectiveness of field hydraulic fractures. To this end a large (460 mm cubic sample) polyaxial cell, with servo-controlled X,Y,Z, pore pressure, crack-mouth-opening-displacement, and bottom hole pressure, was built. Active imaging with embedded seismic diffraction arrays images the geometry of the fracture. Preliminary tests indicate fracture extent can be imaged to within 5%. Unique embeddible high-fidelity particle velocity AE sensors were designed and calibrated to allow determination of fracture source kinematics.

  8. Discussion of examination of a cored hydraulic fracture in a deep gas well

    SciTech Connect

    Nolte, K.G. (Dowell Schlumberger, Tulsa, OK (United States))

    1993-08-01

    Warpinski et al. document information found from a core through a formation after a hydraulic fracture treatment. As they indicate, the core provides the first detailed evaluation of an actual propped hydraulic fracture away from the well and at a significant depth, and this evaluation leads to findings that deviate substantially from the assumptions incorporated into current fracturing models. In this discussion, a defense of current fracture design assumptions is developed. The affirmation of current assumptions, for general industry applications, is based on an assessment of the global impact of the local complexity found in the core. The assessment leads to recommendations for the evolution of fracture design practice.

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

    SciTech Connect

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

    1995-06-01

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

  10. Review article Induced seismicity and hydraulic fracturing for the recovery of

    E-print Network

    Foulger, G. R.

    fractures and a fluid pressure pulse could be transmitted to the fault. Lastly, due to poroelastic in the fault or in fractures connected to the fault. The following pathways for fluid or a fluid pressure pulse mining (M 1.0e5.2); (h) geothermal operations (M 1.0e4.6) and (i) hydraulic fracturing for recovery

  11. Laboratory imaging of stimulation fluid displacement from hydraulic fractures

    SciTech Connect

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

    1996-11-01

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

  12. Laboratory imaging of stimulation fluid displacement from hydraulic fractures

    SciTech Connect

    Tidwell, V.; Parker, M.

    1996-12-31

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

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

    SciTech Connect

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

    2003-07-01

    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.

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

    SciTech Connect

    Laue, M.L.

    1998-02-05

    This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation is used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments are determined, in part, by fracturing an existing test well. Fracture azimuth is predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well has been drilled. Swept-out sand intervals and a poor cement bond behind the 5 in. liner precluded two of the three originally planned hydraulic fracture treatments. All pay intervals behind the 5 in. liner were therefore perforated and stimulated with a non-acid reactive fluid. Following a short production period, the remaining pay intervals in the well, behind the 7 in. liner, were then perforated. The well was returned to production to observe production trends and pressure behavior prior to stimulation of the newer perforations.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    SciTech Connect

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

    1994-01-20

    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.

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

    PubMed

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

    2011-09-25

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

  18. 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...

  19. Fontenelle Field hydraulic fracturing stimulation of the Frontier Formation: Case history

    SciTech Connect

    Martinez, A.D.; Ruffin, B.D.

    1994-12-31

    This paper is a case history of the Frontier Formation hydraulic fracture stimulations applied since 1984 in the Fontenelle Field located in Sweetwater County, Wyoming. The hydraulic fracture treatments have undergone several design changes that have led to a 25% increase in production and a 66% decrease in completion costs. Design changes that have been incorporated to reduce costs include reduction in pad volumes, use of sand versus intermediate strength proppant, reduced pump rates, and the use of water based gels instead of CO{sub 2} foams. Improved production is attributed to improved fracture geometry resulting from 3-D fracture model analysis.

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

    SciTech Connect

    Settari, A.; Raisbeck, J.M.

    1981-11-01

    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.

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

    E-print Network

    Fletcher, Sarah Marie

    2012-01-01

    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 ...

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

    E-print Network

    Holgate, Karen Elaine

    1987-01-01

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

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

    E-print Network

    Podhoretz, Seth

    2013-07-27

    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...

  4. The analysis of liquid loading problems in hydraulically fractured gas wells 

    E-print Network

    Pietsch, Charles Edward

    1986-01-01

    THE ANALYSIS OF LIQUID LOADING PROBLEMS IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by CHARLES EDWARD PIETSCH g~ e~q) Submitted to the Graduate College of Texas A & M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1986 Major Subject: Petroleum Engineering THE ANALYSIS OF LIQUID LOADING PROBLEMS IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by CHARLES EDWARD PIETSCH Approved as to style and content by: Stephen A. Holditch (Chairman...

  5. Hydraulic fracture crack propagation driven by a non-Newtonian fluid

    Microsoft Academic Search

    V. R. Tagirova

    2009-01-01

    The problem of hydraulic fracture crack propagation in a porous medium is considered. The fracture is driven by an incompressible\\u000a viscous fluid with a power-law rheology of the pseudoplastic type. The fluid seepage is described by an equation generalizing\\u000a the Darcy law in the hydraulic approximation. It is shown that the system of governing equations has a power-law self-similar\\u000a solution,

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

    E-print Network

    Holgate, Karen Elaine

    1987-01-01

    EVALUATION OF MASSIVE HYDRAULIC FRACTURING EXPERIMENTS IN THE DEVONIAN SHALES IN LINCOLN COUNTY, WEST VIRGINIA A Thesis by KAREN ELAINE HOLGATE Submitted to the Graduate College of Texas ALM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject: Petroleum Engineering EVALUATION OF MASSIVE HYDRAULIC FRACTURING EXPERIMENTS IN THE DEVONIAN SHALES IN LINCOLN COUNTY, WEST VIRGINIA A Thesis by KAREN ELAINE HDLGATE Approved...

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

    E-print Network

    Santiago Molina, Cesar Alfonso

    1991-01-01

    CHARACTERIZATION AND RESERVOIR EVALUATION OF A HYDRAULICALLY FRACTURED& SHALY GAS RESERVOIR A Thesis by CESAR ALFONSO SANTIAGO MOLINA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 1991 Major Subject: Petroleum Engineering CHARACTERIZATION AND RESERVOIR EVALUATION OF A HYDRAULICALLY FRACTURED, SHALY GAS RESERVOIR A Thesis by CESAR ALFONSO SANTIAGO MOLINA Approved...

  8. Simulation of Hydraulic Fracturing in Low-Permeability Reservoirs

    Microsoft Academic Search

    A. Settari; H. S. Price

    1984-01-01

    Computer-based numerical simulation can be used as a tool for analysis of fracturing treatments and prediction of postfracturing well performance. The physical problem studied involves fracture mechanics, fluid flow, and heat transfer both in the fracture and in the reservoir. The numerical model predicts fracture extension, length, and width; proppant transport and settlement; fracture closure; cleanup; and postfracturing performance under

  9. Quantification of rock stress heterogeneity: Application to hydraulic fracturing of hydrocarbon reservoirs

    NASA Astrophysics Data System (ADS)

    Langenbruch, Cornelius; Shapiro, Serge A.

    2015-04-01

    Fluid injection-induced earthquakes occur due to opening of new and re-activation of pre-existing fractures contained in the rock volume stress-perturbed by the fluid injection. We compare elastic rock heterogeneity measured by borehole logging to the occurrence of seismic events caused by hydraulic fracturing of the corresponding rock sections. Our observations made from two hydraulic fracturing case studies suggest that elastic rock heterogeneity controls the occurrence of fluid injection-induced earthquakes. The seismic events occur preferentially in rock sections characterized by low Poisson's ratio and high Young's modulus. Fracture opening and re-activation probability and the occurrence of associated seismic events should be strongly related to the initial state of stress in the unperturbed reservoir rock. We describe the sedimentary reservoir rock by a perfectly layered linear elastic medium in equilibrium to an externally applied homogeneous far field stress and quantify the relation between stress changes leading to fracture opening and re-activation and elastic rock heterogeneity. We extend existing analytic solutions of stress fluctuations in heterogeneous linear elastic media consisting of elastically isotropic layers to the case of vertical transverse isotropic layers. This allows application to unconventional shale gas reservoirs, which are usually characterized by a high intrinsic anisotropy. We find that magnitudes of rock stress fluctuations originating from elastic rock heterogeneity are significant. Moreover, we show that stress changes leading to fracture opening and re-activation in rocks undergo scale invariance spatial fluctuations. The scale invariant nature of rock stress fluctuations is caused by scale invariant fluctuations of elastic rock properties measured along the borehole. This gives a physical explanation for scale invariance of seismogenic processes. Based on our model, we analyze the physical meaning of a heterogeneity index of rocks, which indicates rocks sections of high Young's modulus and low Poisson's ratio. This index is an indicator of occurrence probability of brittle rock failure during hydraulic reservoir stimulations in the analyzed cases. However, our quantitative study demonstrates that rock failure indicator, which are based solely on elastic properties of rocks cannot have a universal physical meaning. In addition, our results suggest that even though the intermediate principal stress magnitude is not directly involved in the Mohr Coulomb failure criterion, it has a significant influence on the stress changes leading to re-activation and opening of fractures. This finding coincides with observations made during fracturing tests of rock samples in laboratory. In summary, our study demonstrates that stress fluctuations resulting from elastic rock heterogeneity are of significant importance for the seismogenesis of fluid injection-induced earthquakes. The physics of seismogenic processes can be understood by analyzing the physical origin of rock stress fluctuations and their relation to brittle rock failure processes.

  10. A comprehensive model of fluid loss in hydraulic fracturing

    SciTech Connect

    Yi, T.; Peden, J.M. (Heriot-Watt Univ., Edinburgh (United Kingdom))

    1994-11-01

    This paper presents a comprehensive model of the fluid-loss process that occurs in hydraulic fracturing. The model treats the three flow regions in the leakoff process--the filter cake, the invaded zone and the reservoir zone--as a composite system with a rigorous account of the interface between the last two zones. This allows automatic consideration of the variation in pressure drops across the three zones and the inclusion of many variable physical aspects in each region. For the description of the filter cake behavior, effects of the internal filter cake, core length, shear rate, and non-newtonian behavior of fluids have been taken into account. In the invaded zone, the non-Newtonian behavior of the filtrate, the permeability damage caused by the filtrate invasion, and rock and fluid compressibility have been simulated. Different boundary conditions, such as no-flow, constant-pressure, finite, and infinite boundaries, have been incorporated into the model, making it applicable for simulating both laboratory tests and the real leakoff process in fracturing treatments under a variety of conditions. The model has been validated against laboratory and published data. Excellent agreement between predicted results and test data has been achieved. The analyses show that the non-Newtonian behavior f the filtrate represented by the model has a significant effect on leakoff. Leakoff would be considerably underestimated if a Newtonian fluid filtrate, as in the classic theory, were assumed instead of the non-Newtonian system. The authors also show that the variation in pressure drops across the three zones may cause a strong nonlinear relation between leakoff and t 1/2 that cannot be explained by the classic theory because constant pressure drops are assumed.

  11. Hydraulic fracture reorientation in primary and secondary recovery from low-permeability reservoirs

    SciTech Connect

    Wright, C.A.; Conant, R.A.

    1995-12-31

    Hydraulic fracture orientation is critical to both primary and secondary oil recovery in low-permeability reservoirs. Incomplete and often overlapping drainage patterns under primary recovery, as well as inefficient sweep and premature water (or steam) breakthrough under secondary recovery are some of the common production problems that often result from hydraulic fracture reorientation. Often, hydraulic fracture orientation is measured on a few wells, and then generalized across the entire field under development. This characterization of regional fracture (stress) orientation is then assumed constant over the development life of the field. A wealth of recent observations have definitively shown that fracture (stress) orientation in low-permeability reservoirs can be profoundly affected by production activities. Hydraulic fracture reorientation has been observed on dozens of staged fracture treatments (in several fields) under both primary and secondary recovery. A summary of collected field data from three extensive field studies is presented. The production impact of fracture reorientation on both primary and secondary recovery schemes is addressed; and strategies are presented which utilize the recent findings for both enhancing primary recovery and mitigating some common problems with secondary recovery. The discussion of reorientation mechanisms is greatly enlightened by recent data which reveals a startling correlation between observed fracture reorientation and indirect measurements of reservoir compaction.

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

    Microsoft Academic Search

    Juncai Fan

    2001-01-01

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

  13. Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations 

    E-print Network

    Zhang, Junjing

    2014-07-10

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

  14. Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations

    E-print Network

    Zhang, Junjing

    2014-07-10

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

  15. Method for hydraulic fracture propagation in hydrocarbon-bearing formations

    SciTech Connect

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

    1987-01-13

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

  16. Fracture detection using a grounded subsurface vertical electric dipole

    SciTech Connect

    Zhou, Q.; Lee, K.H.; Goldstein, N.E.; Morrison, H.F.; Becker, A.

    1986-08-01

    In this paper we study the scattered magnetic field above the surface of the earth due to a buried sheet-like conductor excited by a grounded and oscillating vertical electric dipole (G.V.E.D.) in the earth. The significance of this technique for the detection of water-filled fractures is that there is no magnetic field in the air, assuming that the displacement current is negligible, so long as the G.V.E.D. source is buried in a layered half-space. If any signal is detected it must be due to the presence of a 2-D or 3-D inhomogeneity, such as a sheet-like conductor. Using a numerical modeling approach, we calculated the strength and anomaly shape of the secondary magnetic field from the sheet to determine a G.V.E.D. is a suitable source detecting a major conductive fracture zone.

  17. 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

    Peirce, Anthony

    #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

  18. FAST TRACK PAPER: The creation of an asymmetric hydraulic fracture as a result of driving stress gradients

    Microsoft Academic Search

    T. Fischer; S. Hainzl; T. Dahm

    2009-01-01

    Hydraulic fracture stimulation is frequently performed in hydrocarbon reservoirs and geothermal systems to increase the permeability of the rock formation. These hydraulic fractures are often mapped by hypocentres of induced microearthquakes. In some cases microseismicity exhibits asymmetry relative to the injection well, which can be interpreted by unequal conditions for fracture growth at opposite sides of the well or by

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

    SciTech Connect

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

    1996-12-31

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

  20. Role of permeability and storage in the initiation and propagation of natural hydraulic fractures

    Microsoft Academic Search

    David F. Boutt; Laurel Goodwin; Brian J. O. L. McPherson

    2009-01-01

    Joint sets within sedimentary basins are commonly interpreted to have formed by tensile failure in conditions where pore fluid pressure was elevated. Such tensile fractures are inferred to be a part of the process that relieves high fluid pressure by locally increasing rock permeability. In spite of the importance of this feedback mechanism, the detailed mechanics of hydraulic fracture genesis

  1. HYFRACP3D. Finite Element Code for 3D-Hydraulic Fracture Propagation Equations (3-layer)

    Microsoft Academic Search

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

    1985-01-01

    HYFRACP3D is a finite element program for simulation of a pseudo three-dimensional fracture geometries with a two-dimensional planar solution. The model predicts the height, width and winglength over time for a hydraulic fracture propagating in a three-layered system of rocks with variable rock mechanics properties.

  2. HYFRACP3D. Finite Element Code For 3D-Hydraulic Fracture Propagation Equations (3-layer)

    Microsoft Academic Search

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

    1985-01-01

    HYFRACP3D is a finite element program for simulation of a pseudo three-dimensional fracture geometries with a two-dimensional planar solution. The model predicts the height, width and winglength over time for a hydraulic fracture propagating in a three-layered system of rocks with variable rock mechanics properties.

  3. Uplifts and tilts at earth's surface induced by pressure transients from hydraulic fractures

    Microsoft Academic Search

    1990-01-01

    The pressure transient that spreads through the formation during and after a hydraulic fracture treatment pressurizes the formation and induces a certain swelling. This swelling and the accompanying uplift at the earth's surface can be estimated with poroelastic theory. The uplift may produce a significant signal in tiltmeter devices placed at the surface. This paper reports six fracturing treatments in

  4. Combined use of straddle packer testing and FLUTe profiling for hydraulic testing in fractured rock boreholes

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    A combination of high resolution hydraulic tests using straddle packers and transmissivity (T) profiling using the FLUTe flexible liner method (liner profiling) in densely fractured rock boreholes is shown to be efficient for the determination of the vertical distribution of T along the entire hole. The liner T profiling method takes a few hours or less to scan the entire borehole length resulting in a T profile. Under favorable conditions this method has good reliability for identifying the highest T zones identified by distinct decreases in liner velocity when these zones are covered by the descending liner. In contrast, for one short test interval (e.g., 1-2 m) the multiple-test, straddle-packer method takes a few hours to measure T with good precision and accuracy using a combination of steady-state and transient tests (e.g., constant head step tests, slug tests, and constant rate pumping tests). Because of the time consuming aspect of this multiple-test method, it is most efficient in each borehole to conduct straddle packer testing only in priority zones selected after assessment of other borehole data collected prior to packer testing. The T profile from the liner method is instrumental in selecting high permeable zones for application of the multiple-test method using straddle packers, which in turn, refines the T estimation from the liner profile. Results from three boreholes in densely fractured sandstone demonstrate this approach showing the synergistic use of the methods with emphasis on information important for determining hydraulic apertures.

  5. Flow characteristics of hydraulic fracture proppants subjected to repeated production cycles

    SciTech Connect

    Holditch, S.A.; Blakeley, D.M. (Texas A and M Univ. (US))

    1992-02-01

    When fracture proppants are subjected to cyclic loading, the conductivity of the fracture is reduced. This paper presents laboratory results to quantify the degradation of sand and intermediate-strength proppants (ISP's) as closure stress is loaded cyclically to the proppant. The results imply that, if a deep gas well is opened and then shut in repeatedly, permanent damage to the hydraulic fracture will occur.

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

    SciTech Connect

    Zyvoloski, G.

    1985-01-01

    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.

  7. Optimizing well spacing and hydraulic-fracture design for economic recovery of coalbed methane

    SciTech Connect

    Zuber, M.D. (Holditch (S.A.) and Associates, Inc., College Station, TX (USA)); Kuuskraa, V.A. (ICF, Inc., Fairfax, VA (USA)); Sawyer, W.K. (Mathematical and Computer Services Inc., Danville, VA (US))

    1990-03-01

    Conventionally, proper well spacing and stimulation govern the economic attractiveness of producing natural gas from coalbeds. To provide an analytical foundation for this empirical evidence, reservoir simulation and economic analyses were conducted to gain insights into the optimum well spacing and hydraulic-fracturing treatments in typical good and poor geologic settings of the Oak Grove field in Alabama. The authors report their study of the economic benefit of gel-based fracturing treatments, the optimal well spacing for higher- and lower-permeability settings, and how to establish proper values for permeability and achievable hydraulic-fracture dimensions for optimal well spacing.

  8. A hybrid, neuro-genetic approach to hydraulic fracture treatment design and optimization

    SciTech Connect

    Mohaghegh, S.; Balan, B.; Ameri, S.; McVey, D.S.

    1996-12-31

    This paper summarizes the efforts conducted toward the development of a new and novel methodology for optimal design of hydraulic fracture treatments in a gas storage field. What makes this methodology unique is its capability to provide engineers with a near optimum design of a frac job despite very little (almost none) reservoir data availability. Lack of engineering data for hydraulic fracture design and evaluation had made use of 2D or 3D hydraulic fracture simulators impractical. As a result, prior designs of hydraulic frac jobs had been reduced to guess works and in some cases dependent on engineers with many years of experience on this particular field, who had developed an intuition about this formation and its possible response to different treatments. This was the main cause of several frac job failures every year. On the other hand, in case of relocation of engineers with experience on this particular field the risk of even more frac job failures was imminent.

  9. Coordinated studies in support of hydraulic fracturing of coalbed methane. Annual report, January 1993-April 1994

    SciTech Connect

    Penny, G.S.; Conway, M.W.

    1994-08-01

    The production of natural gas from coal typically requires stimulation in the form of hydraulic fracturing and, more recently, cavity completions. The results of hydraulic fracturing treatments have ranged from extremely successful to less than satisfactory. The purpose of this work is to characterize common and potential fracturing fluids in terms of coal-fluid interactions to identify reasons for less than satisfactory performance and to ultimately devise alternative fluids and treatment procedures to optimize production following hydraulic fracturing. The laboratory data reported herein has proven helpful in designing improved hydraulic fracturing treatments and remedial treatments in the Black Warrior Basin. Acid inhibitors, scale inhibitors, additives to improve coal relative permeability to gas, and non-damaging polymer systems for hydraulic fracturing have been screened in coal damage tests. The optimum conditions for creating field-like foams in the laboratory have been explored. Tests have been run to identify minimum polymer and surfactant concentrations for applications of foam in coal. The roll of 100 mesh sand in controlling leakoff and impairing conductivity in coal has been investigated. The leakoff and proppant transport of fluids with breaker has been investigated and recommendations have been made for breaker application to minimize damage potential in coal. A data base called COAL`S has been created in Paradox (trademark) for Windows to catalogue coalbed methane activities in the Black Warrior and San Juan Basins.

  10. Vertical cross contamination of trichloroethylene in a borehole in fractured sandstone

    USGS Publications Warehouse

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

    2005-01-01

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

  11. Implementation of Linear Pipe Channel Network to Estimate Hydraulic Parameters of Fractured Rock Masses

    NASA Astrophysics Data System (ADS)

    Han, J.; Um, J. G.; Wang, S.

    2014-12-01

    Modeling of fluid flow is important in geological, petroleum, environmental, civil and mining engineering. Fluid flow through fractured hard rock is very much dependent on the fracture network pattern in the rock mass and on the flow behavior through these fractures. This research deals with fluid flow behavior through fractures at an abandoned copper mine in southeast Korea. An injection well and three observation wells were installed at the mine site to monitor the hydraulic heads induced by injection of fresh water. A series of packer tests were performed to estimate the rock mass permeability and corresponding effective hydraulic aperture of the fractures. The three dimensional stochastic fracture network model was built and validated for the mine site. The two dimensional linear pipe network systems were constructed in directions of the observation wells using the fracture network model. A procedure of the fluid flow analysis on two dimensional discrete domain was applied to estimate the conductance, flow quantity and nodal head in the 2-D linear pipe channel network. The present results indicate that fracture geometry parameters (orientation, density and size) play an important role in the hydraulic characteristics of fractured rock masses.

  12. Coordinated studies in support of hydraulic fracturing of coalbed methane. Annual report, November 1991-December 1992

    SciTech Connect

    Not Available

    1993-04-01

    The purpose of the work is to characterize common and potential fracturing fluids in terms of coal-fluid interactions to identify reasons for less than satisfactory performance and to ultimately devise alternative fluids and treatment procedures to optimize production following hydraulic fracturing. The laboratory data reported herein has proven helpful in designing improved hydraulic fracturing treatments and remedial treatments in the Black Warrior Basin. Acid inhibitors, scale inhibitors, additives to improve coal relative permeability to gas, and non-damaging polymer systems for hydraulic fracturing have been screened in coal damage tests. The optimum conditions for creating field-like foams in the laboratory have been explored. Tests have been run to identify minimum polymer and surfactant concentrations for applications of foam in coal. The roll of 100 mesh sand in controlling leakoff and impairing conductivity in coal has been investigated.

  13. Induced microseismicity resulting from hydraulic fracturing is routinely monitored to provide essential information about a threedimensional (3D) geometrical shape of fracture

    E-print Network

    Cerveny, Vlastislav

    225 Abstract Induced microseismicity resulting from hydraulic fracturing is routinely monitored to provide essential information about a three­dimensional (3­D) geometrical shape of fracture on the scale to the fracture growth may provide crucial information about the fracture itself and reservoir properties, which

  14. Modelling Subduction Zone Magmatism Due to Hydraulic Fracture

    NASA Astrophysics Data System (ADS)

    Lawton, R.; Davies, J. H.

    2014-12-01

    The aim of this project is to test the hypothesis that subduction zone magmatism involves hydraulic fractures propagating from the oceanic crust to the mantle wedge source region (Davies, 1999). We aim to test this hypothesis by developing a numerical model of the process, and then comparing model outputs with observations. The hypothesis proposes that the water interconnects in the slab following an earthquake. If sufficient pressure develops a hydrofracture occurs. The hydrofracture will expand in the direction of the least compressive stress and propagate in the direction of the most compressive stress, which is out into the wedge. Therefore we can calculate the hydrofracture path and end-point, given the start location on the slab and the propagation distance. We can therefore predict where water is added to the mantle wedge. To take this further we have developed a thermal model of a subduction zone. The model uses a finite difference, marker-in-cell method to solve the heat equation (Gerya, 2010). The velocity field was prescribed using the analytical expression of cornerflow (Batchelor, 1967). The markers contained within the fixed grid are used to track the different compositions and their properties. The subduction zone thermal model was benchmarked (Van Keken, 2008). We used the hydrous melting parameterization of Katz et.al., (2003) to calculate the degree of melting caused by the addition of water to the wedge. We investigate models where the hydrofractures, with properties constrained by estimated water fluxes, have random end points. The model predicts degree of melting, magma productivity, temperature of the melt and water content in the melt for different initial water fluxes. Future models will also include the buoyancy effect of the melt and residue. Batchelor, Cambridge UP, 1967. Davies, Nature, 398: 142-145, 1999. Gerya, Cambridge UP, 2010. Katz, Geochem. Geophys. Geosy, 4(9), 2003 Van Keken et.al. Phys. Earth. Planet. In., 171:187-197, 2008.

  15. Hydraulic fracture orientation and production/injection induced reservoir stress changes in diatomite waterfloods

    SciTech Connect

    Wright, C.A.; Conant, R.A.; Golich, G.M.; Bondor, P.L.; Murer, A.S.; Dobie, C.A.

    1995-12-31

    This paper summarizes the (preliminary) findings from extensive field studies of hydraulic fracture orientation in diatomite waterfloods and related efforts to monitor the induced surface subsidence. Included are case studies from the Belridge and Lost Hills diatomite reservoirs. The primary purpose of the paper is to document a large volume of tiltmeter hydraulic fracture orientation data that demonstrates waterflood-induced fracture reorientation--a phenomenon not previously considered in waterflood development planning. Also included is a brief overview of three possible mechanisms for the observed waterflood fracture reorientation. A discussion section details efforts to isolate the operative mechanism(s) from the most extensive case study, as well as suggesting a possible strategy for detecting and possibly mitigating some of the adverse effects of production/injection induced reservoir stress changes--reservoir compaction and surface subsidence as well as fracture reorientation.

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

    SciTech Connect

    Groenenboom, J.; Falk, J.

    2000-04-01

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

  17. Simulation of hydraulic fracturing in low-permeability reservoirs

    SciTech Connect

    Settari, A.; Price, M.S.

    1984-04-01

    Computer-based numerical simulation can be used as a tool for analysis of fracturing treatments and prediction of postfracturing well performance. The physical problem studied involves fracture mechanics, fluid flow, and heat transfer both in the fracture and in the reservoir. The numerical model predicts fracture extension, length, and width; proppant transport and settlement; fracture closure; cleanup; and postfracturing performance under different producing conditions. The number of physical features that are customarily neglected in fracture designs have been incorporated in the present model. These include stress-sensitive reservoir properties, proper two-phase calculation of leakoff and cleanup, stress-dependent fracture permeability and temperature- and time-dependent fracturing fluid rheology. The utility and a priori predictive capability of the model is illustrated with two examples of fracturing jobs. The first example is a marginal gas well stimulated by a medium-size gelled-water fracturing job. The second example is a massive foam fracture in the Elmworth basin. In both cases, the simulator predicted results that are in good agreement with the observed productivity.

  18. Assessing Microbial Activity in Marcellus Shale Hydraulic Fracturing Fluids

    NASA Astrophysics Data System (ADS)

    Wishart, J. R.; Morono, Y.; Itoh, M.; Ijiri, A.; Hoshino, T.; Inagaki, F.; Verba, C.; Torres, M. E.; Colwell, F. S.

    2014-12-01

    Hydraulic fracturing (HF) produces millions of gallons of waste fluid which contains a microbial community adapted to harsh conditions such as high temperatures, high salinities and the presence of heavy metals and radionuclides. Here we present evidence for microbial activity in HF production fluids. Fluids collected from a Marcellus shale HF well were supplemented with 13C-labeled carbon sources and 15N-labeled ammonium at 25°C under aerobic or anaerobic conditions. Samples were analyzed for 13C and 15N incorporation at sub-micrometer scale by ion imaging with the JAMSTEC NanoSIMS to determine percent carbon and nitrogen assimilation in individual cells. Headspace CO2 and CH4 were analyzed for 13C enrichment using irm-GC/MS. At 32 days incubation carbon assimilation was observed in samples containing 1 mM 13C-labeled glucose under aerobic and anaerobic conditions with a maximum of 10.4 and 6.5% total carbon, respectively. Nitrogen assimilation of 15N ammonium observed in these samples were 0.3 and 0.8% of total nitrogen, respectively. Head space gas analysis showed 13C enrichment in CH4 in anaerobic samples incubated with 1mM 13C-labeled bicarbonate (2227 ‰) or methanol (98943 ‰). Lesser 13C enrichment of CO2 was observed in anaerobic samples containing 1 mM 13C-labeled acetate (13.7 ‰), methanol (29.9 ‰) or glucose (85.4 ‰). These results indicate metabolic activity and diversity in microbial communities present in HF flowback fluids. The assimilation of 13C-labeled glucose demonstrates the production of biomass, a critical part of cell replication. The production of 13CO2 and 13CH4 demonstrate microbial metabolism in the forms of respiration and methanogenesis, respectively. Methanogenesis additionally indicates the presence of an active archaeal community. This research shows that HF production fluid chemistry does not entirely inhibit microbial activity or growth and encourages further research regarding biogeochemical processes occurring in Marcellus shale HF wells. Biogeochemical activity may impact the efficacy of HF and natural gas production as well as the chemistry of produced fluids which have become an environmental and public health concern.

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

    SciTech Connect

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

    1991-09-01

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

  20. Coordinated studies in support of hydraulic fracturing of coalbed methane. Annual report, June 1990-October 1991

    SciTech Connect

    Penny, G.S.; Conway, M.W.

    1992-04-01

    The production of natural gas coal typically requires stimulation in the form of hydraulic fracturing. The results of hydraulic fracturing treatments have ranged from highly successful to less than satisfactory. The approach in the work has been to experimentally evaluate parameters that pertain to coal fluid interactions during hydraulic fracturing and post-frac production and then apply the findings to the selection of fracturing fluids and treatment design. Evaluated parameters include leakoff through cleats, pressure drops through cleated slots with slurries, proppant transport, conductivity, and coal matrix damage due to fracturing fluids. Some conclusions from the work include (1) 100 mesh sand alone can control leakoff through cleats; (2) coal faces alone do not increase pressure drop through fractures with slurries; (3) restrictions approaching 2 proppant diameters are required to see pressure increases; (4) borate fluid pH's of 9.5 are required for transport; (5) mixed proppant conductivities of 100 mesh and 16/30 can be 50% lower than the larger proppant; (6) guar based fracturing fluids can cause up to 90% permeability damage to the coal matrix; (7) HEC containing foams provide the best cleanup in the laboratory (only 10 to 30% damage and have shown excellent results in field trials); and (8) expanded use of COMPAS is recommended to document field results.

  1. A new hydraulic fracture tip mechanism in a statistically homogeneous medium

    SciTech Connect

    Chudnovsky, A.; Fan, J.; Shulkin, Y. [Univ of Chicago, IL (United States)] [and others

    1996-12-31

    This paper presents a new hydraulic fracture (HF) tip mechanism observed in a statistically homogeneous porous rock. HF tip mechanisms are widely recognized to be responsible for discrepancies between field observations and HF model predictions. Current proposed tip mechanisms used in HF geometry simulations require field calibration and are not truly predictive based on lab- and/or field-scale material property data. Matching field pressure data often gives significantly different material property values from those measured in the lab. This paper reports studies of a hydraulic fracture created in an 18-inch cubic block of Lueders limestone that reveals random {open_quotes}bridges{close_quotes} connecting the opposing fracture faces. Observation of the bridges suggests the existence of a crack tip zone that resembles the process zone widely reported for various other materials. The existence of a process zone significantly changes many fracture parameters in comparison with linear fracture mechanics predictions (e.g., fracture length and width, net pressure, etc.). A new model is proposed to account for the observed crack tip process zone (PZ). The model is comprised of two complementary parts: (1) a statistical characterization and simulation of the bridging phenomenon, and (2) a thermodynamics-based model of the growth of the crack and PZ. The main challenges and future research topics in Hydraulic Fracturing are also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  3. A method to estimate multizone injection profiles during hydraulic fracturing

    SciTech Connect

    Elbel, J.L. (Dowell Schlumberger, Tulsa, OK (United States))

    1993-05-01

    When two or more fractures are created during multizone fracturing, proppant penetration in some zones may be inadequate. The injection rate into each zone is governed by fracture height, rock modulus, fluid loss, stress contrasts, and perforation friction pressure. This paper presents an expression for determining the injection ratios during the fracturing of individually confined layers assuming Perkins-Kern-Nordgren geometry. This expression has been combined with previously published equations for determining fracture geometry, efficiency, pad volume, and perforation friction to allow simulation of the fracture geometry for any number of layers. Simulations show the effect of parameters on the injection profile and resultant geometry. Methods of minimizing adverse geometry also are discussed.

  4. Experimental study of nonlinear effects in hydraulic fracture propagation

    SciTech Connect

    Pater, C.J. de; Weijers, L.; Savic, M.; Wolf, K.H.A.A. (Delft Univ. of Technology (Netherlands)); Hoek, P.J. van den (Royal/Dutch Shell E and P Lab., Rijswijk (Netherlands)); Barr, D.T. (Resources Engineering Systems, Inc., Cambridge, MA (United States))

    1994-11-01

    The authors conducted fracture propagation experiments on blocks of cement paste, cement paste with sand, and a tight outcrop sandstone rock. A novel acoustic monitoring system was developed for measuring the fracture profile and radius during the tests. Results of laboratory tests on cement agreed with numerical simulations based on elastic rock deformation and linear elastic fracture mechanics. Tests at confining stresses of 20 and 23 MPa gave higher pressures than predicted.

  5. WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS?

    E-print Network

    Paris-Sud XI, Université de

    .e.), as their simplicity of operation, low cost and reliable treatment efficiency often fit with the limited Contact: ania.morvannou@irstea.fr Abstract. Modeling water flow in a VFCW is a prerequisite to model wastewater treatment using process based filtering models. As for soils, when the vertical structure varies

  6. Discussion of comparison study of hydraulic fracturing models -- Test case: GRI Staged Field Experiment No. 3

    SciTech Connect

    Cleary, M.P.

    1994-02-01

    This paper provides comments to a companion journal paper on predictive modeling of hydraulic fracturing patterns (N.R. Warpinski et. al., 1994). The former paper was designed to compare various modeling methods to demonstrate the most accurate methods under various geologic constraints. The comments of this paper are centered around potential deficiencies in the former authors paper which include: limited actual comparisons offered between models, the issues of matching predictive data with that from related field operations was lacking or undocumented, and the relevance/impact of accurate modeling on the overall hydraulic fracturing cost and production.

  7. In-situ stress variations and hydraulic-fracture containment in layered rock: observations from a mineback experiment

    Microsoft Academic Search

    L. W. Teufel; N. R. Warpinski

    1983-01-01

    The purpose of this paper is to summarize the results of realistic in-situ experiments which have been conducted in an existing tunnel complex at the US Department of Energy's Nevada Test Site to examine hydraulic fracture propagation in layered rock under many different conditions. These facilities are ideal for hydraulic fracture experiments because they provide a realistic in-situ medium with

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

    E-print Network

    Paris-Sud XI, Université de

    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 level fluctuations as input and output respectively. The spatial variability of the response to recharge

  9. Dynamic fluid loss in hydraulic fracturing under realistic shear conditions in high-permeability rocks

    SciTech Connect

    Navarrete, R.C.; Cawiezel, K.E.; Constien, V.G. [Dowell Schlumberger, Tulsa, OK (United States)

    1996-08-01

    A study of the dynamic fluid loss of hydraulic fracturing fluids under realistic shear conditions is presented. During a hydraulic fracturing treatment, a polymeric solution is pumped under pressure down the well to create and propagate a fracture. Part of the fluid leaks into the rock formation, leaving a skin layer of polymer or polymer filter cake, at the rock surface or in the pore space. This study focuses on the effects of shear rate and permeability on dynamic fluid-loss behavior of crosslinked and linear fracturing gels. Previous studies of dynamic fluid loss have mainly been with low-permeability cores and constant shear rates. Here, the effect of shear history and fluid-loss additive on the dynamic leakoff of high-permeability cores is examined.

  10. Hydraulic fracturing to enhance the remediation of DNAPL in low permeability soils

    SciTech Connect

    Murdoch, L. [Univ. of Cincinnati, OH (United States); Slack, B. [FRX Inc., Cincinnati, OH (United States)

    1996-08-01

    Meager rates of fluid flow are a major obstacle to in situ remediation of low permeability soils. This paper describes methods designed to avoid that obstacle by creating fractures and filling them with sand to increase well discharge and change paths of fluid flow in soil. Gently dipping fractures 10 m in maximum dimension and 1 to 2 cm thick can be created in some contaminated soils at depths of a few in or greater. Hydraulic fractures can also be used to create electrically conductive layers or to deliver granules of chemically or biologically active compounds that will degrade contaminants in place. Benefits of applying hydraulic fractures to DNAPL recovery include rates of fluid recovery, enhancing upward gradients to improve hydrodynamic stabilization, forming flat-lying reactive curtains to intersect compounds moving downward, or improving the performance of electrokinetics intended to recover compounds dissolved in water. 30 refs., 7 figs., 1 tab.

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

    SciTech Connect

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

    1985-01-01

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

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

    SciTech Connect

    Rauscher, B.D.

    1996-12-31

    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.

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

    PubMed

    Fritz, Brad G; Mackley, Rob D

    2010-01-01

    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

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

    SciTech Connect

    Not Available

    1981-06-01

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

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

    SciTech Connect

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

    1992-05-01

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

  16. Diffraction of seismic waves by cracks with application to hydraulic fracturing

    SciTech Connect

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

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  18. 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

    Peirce, Anthony

    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

  19. 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

    Peirce, Anthony

    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

  20. Simulation of quasi-static hydraulic fracture propagation in porous media with XFEM

    NASA Astrophysics Data System (ADS)

    Juan-Lien Ramirez, Alina; Neuweiler, Insa; Löhnert, Stefan

    2015-04-01

    Hydraulic fracturing is the injection of a fracking fluid at high pressures into the underground. Its goal is to create and expand fracture networks to increase the rock permeability. It is a technique used, for example, for oil and gas recovery and for geothermal energy extraction, since higher rock permeability improves production. Many physical processes take place when it comes to fracking; rock deformation, fluid flow within the fractures, as well as into and through the porous rock. All these processes are strongly coupled, what makes its numerical simulation rather challenging. We present a 2D numerical model that simulates the hydraulic propagation of an embedded fracture quasi-statically in a poroelastic, fully saturated material. Fluid flow within the porous rock is described by Darcy's law and the flow within the fracture is approximated by a parallel plate model. Additionally, the effect of leak-off is taken into consideration. The solid component of the porous medium is assumed to be linear elastic and the propagation criteria are given by the energy release rate and the stress intensity factors [1]. The used numerical method for the spatial discretization is the eXtended Finite Element Method (XFEM) [2]. It is based on the standard Finite Element Method, but introduces additional degrees of freedom and enrichment functions to describe discontinuities locally in a system. Through them the geometry of the discontinuity (e.g. a fracture) becomes independent of the mesh allowing it to move freely through the domain without a mesh-adapting step. With this numerical model we are able to simulate hydraulic fracture propagation with different initial fracture geometries and material parameters. Results from these simulations will also be presented. References [1] D. Gross and T. Seelig. Fracture Mechanics with an Introduction to Micromechanics. Springer, 2nd edition, (2011) [2] T. Belytschko and T. Black. Elastic crack growth in finite elements with minimal remeshing. Int. J. Numer. Meth. Engng. 45, 601-620, (1999)

  1. Mathematical modeling and simulation analysis of hydraulic fracture propagation in three-layered poro-elastic media

    SciTech Connect

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

    1992-11-01

    Hydraulic fracturing plays a pivotal role in the enhancement of oil and gas production recovery from low permeability reservoirs. The process of hydraulic fracturing entails the generation of a fracture by pumping fluids blended with special chemicals and proppants into the payzone at high injection rates and pressures to extend and wedge fractures. The mathematical modeling of hydraulically induced fractures generally incorporates coupling between the formation elasticity, fracture fluid flow, and fracture mechanics equations governing the formation structural responses, fluid pressure profile, and fracture growth. Two allied unsymmetric elliptic fracture models are developed for fracture configuration evolutions in three-layered rock formations. The first approach is based on a Lagrangian formulation incorporating pertinent energy components associated with the formation structural responses and fracture fluid flow. The second model is based on a generalized variational principle, introducing an energy rate related functional. These models initially simulate a penny-shaped fracture, which becomes elliptic if the crack tips encounters (upper and/or lower) barriers with differential reservoir properties (in situ stresses, 16 elastic moduli, and fracture toughness-contrasts and fluid leak-off characteristics). The energy rate component magnitudes are determined to interpret the governing hydraulic fracture mechanisms during fracture evolution. The variational principle is extended to study the phenomenon and consequences of fluid lag in fractures. Finally, parametric sensitivity and energy rate investigations to evaluate the roles of controllable hydraulic treatment variables and uncontrollable reservoir property characterization parameters are performed. The presented field applications demonstrate the overall capabilities of the developed models. These studies provide stimulation treatment guidelines for fracture configuration design, control, and optimization.

  2. Three-dimensional hydraulic fracture simulation using fixed grid finite element algorithms

    SciTech Connect

    Lee, T.S. (Sogang Univ., Seoul (Korea, Republic of). Dept. of Mechanical Engineering); Advani, S.H.; Pak, C.K. (Lehigh Univ., Bethlehem, PA (United States))

    1994-03-01

    A three-dimensional hydraulic fracture simulator (HYFFIX) is reformulated using finite element methodology and a newly adapted fixed grid. The numerical procedures for the coupled equations governing the fracture width, fluid pressure, and evolution of equilibrium planar crack in layered media are summarized. Fixed grid mesh control algorithms for the efficient tracking of the moving crack/fracture fluid front are detailed. The introduction of these novel algorithms in the simulator makes it numerically efficient and stable, in comparison to previously reported models which utilize migrating mesh techniques. Due to the enhanced numerical efficiency and compactness of the refined code, the model can also be readily implemented on a workstation or microcomputer.

  3. 79 FR 28664 - Hydraulic Fracturing Chemicals and Mixtures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2014-05-19

    ...mixtures and the mechanism for obtaining...information. This mechanism could be regulatory...incentives and recognition programs that...fracturing. This mechanism could be regulatory...incentives and recognition programs...

  4. The evolution of hydraulic fracturing in the Almond formation

    SciTech Connect

    Cramer, D.D.

    1995-12-31

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

  5. Geometry of hydraulic fractures induced from horizontal wellbores

    SciTech Connect

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

    1994-05-01

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

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

    Microsoft Academic Search

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

    2006-01-01

    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

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

    Microsoft Academic Search

    Stephen L. Karner

    2006-01-01

    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

  8. Interface test series: An in situ study of factors affecting the containment of hydraulic fractures

    Microsoft Academic Search

    N. R. Warpinski; S. J. Finley; W. C. Vollendorf; M. Obrien; E. Eshom

    1982-01-01

    In situ experiments, which are accessible for direct observation by mineback, were conducted to determine the effect that material-property interfaces and in situ stress differences have on hydraulic fracture propagation and the resultant overall geometry. These experiments show conclusively that a difference in elastic modulus at a geologic interface has little or no effect on crack growth and, therefore, is

  9. Preliminary stress measurements in central California using the hydraulic fracturing technique

    Microsoft Academic Search

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

    1977-01-01

    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

  10. COMPARISON OF PNEUMATIC AND HYDRAULIC FRACTURING FOR EMPLACEMENT OF TREATMENT MATERIALS IN LOW-PERMEABILITY FORMATIONS

    Microsoft Academic Search

    Mark Strong; Craig Sprinkle; Denis Ewing; Dan Owens; Capt. Brian Ventura; John J. Liskowitz

    2004-01-01

    Pilot tests were performed at t he Marine Corps Logistics Base (MCLB) located in Albany, Georgia to evaluate the performance of pneumatic and hydraulic frac- turing for emplacement of in situ biological substrates\\/electron donors into low per- meability alluvium and Ocala Limestone (part of the Floridan aquifer system). The performance of pneumatic fracturing for emplacement of in situ chemical oxidation

  11. An Asymptotic Framework for Finite Hydraulic Fractures Including Leak-Off

    Microsoft Academic Search

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

    2007-01-01

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

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

    SciTech Connect

    Stephen L. Karner, Ph.D

    2006-02-01

    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.

  13. Microseismic mapping of hydraulic fractures using multi-level wireline receivers

    SciTech Connect

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

    1995-07-01

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

  14. Techniques for determining subsurface stress direction and assessing hydraulic fracture azimuth

    SciTech Connect

    Hill, R.E.; Peterson, R.E.; Warpinski, N.R.; Lorenz, J.C.; Teufel, L.W. [Sandia National Labs., Albuquerque, NM (United States); Aslakson, J.K.

    1994-12-31

    This reference paper reviews and describes 15 techniques for determining hydraulic fracture azimuth. The techniques described are categorized into core-based, borehole-based, near-wellbore, and regional geologic indicators that can be used to predict or measure hydraulic fracture azimuth. The core based methods include: (1) circumferential velocity anisotropy, (2) anelastic strain recovery, (3) differential strain curve analysis, (4) axial point load tests, (5) petrographic examination of microcracks, (6) overcoming of archived core, (7) drilling-induced fractures in core, and (8) direct observation of over-cored open-hole stress test fractures. The borehole based techniques include: (9) borehole breakouts, (10) borehole deformation, (11) borehole imaging of drilling induced fractures, and (12) directional gamma ray logging. The near-wellbore techniques provided data on the orientation of the fracture induced during an actual fracture treatment and include: (13) microseismic logging and (14) earth tilt surveys. Finally there are the geologic indicators (Method 15) including earthquake focal mechanisms, fault slip data, surface mapping of neotectonic joints, and volcanic vent alignment. These regional data have been compiled for the World Stress Mapping Project and many maps are available that can be used as a first approximation of stress direction. Experience has shown that the more techniques that can be used in a single well or field, the more reliable the result. The concept or theoretical basis for each technique as well as the benefits and limitations of the techniques are described.

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

    SciTech Connect

    Warpinski, N.R.; Drozda, P.M. [Sandia National Labs., Albuquerque, NM (United States); Wright, T.B. [and others

    1996-12-31

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

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

    SciTech Connect

    David S. Schechter

    2003-10-01

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.

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

    SciTech Connect

    David S. Schechter

    2004-04-26

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on investigating the effect of CO{sub 2} injection rates in homogeneous and fractured cores on oil recovery and a strategy to mitigate CO{sub 2} bypassing in a fractured core.

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

    SciTech Connect

    Not Available

    1981-02-01

    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.

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

    E-print Network

    Paris-Sud XI, Université de

    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

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

    SciTech Connect

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

    1997-05-01

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

  1. Influence of Concentration and Salinity on the Biodegradability of Organic Additives in Hydraulic Fracturing Fluid

    NASA Astrophysics Data System (ADS)

    Mouser, P. J.; Kekacs, D.

    2014-12-01

    One of the risks associated with the use of hydraulic fracturing technologies for energy development is the potential release of hydraulic fracturing-related fluids into surface waters or shallow aquifers. Many of the organic additives used in hydraulic fracturing fluids are individually biodegradable, but little is know on how they will attenuate within a complex organic fluid in the natural environment. We developed a synthetic hydraulic fracturing fluid based on disclosed recipes used by Marcellus shale operators to evaluate the biodegradation potential of organic additives across a concentration (25 to 200 mg/L DOC) and salinity gradient (0 to 60 g/L) similar to Marcellus shale injected fluids. In aerobic aqueous solutions, microorganisms removed 91% of bulk DOC from low SFF solutions and 57% DOC in solutions having field-used SFF concentrations within 7 days. Under high SFF concentrations, salinity in excess of 20 g/L inhibited organic compound biodegradation for several weeks, after which time the majority (57% to 75%) of DOC remained in solution. After SFF amendment, the initially biodiverse lake or sludge microbial communities were quickly dominated (>79%) by Pseudomonas spp. Approximately 20% of added carbon was converted to biomass while the remainder was respired to CO2 or other metabolites. Two alcohols, isopropanol and octanol, together accounted for 2-4% of the initial DOC, with both compounds decreasing to below detection limits within 7 days. Alcohol degradation was associated with an increase in acetone at mg/L concentrations. These data help to constrain the biodegradation potential of organic additives in hydraulic fracturing fluids and guide our understanding of the microbial communities that may contribute to attenuation in surface waters.

  2. Mechanisms and impact of damage resulting from hydraulic fracturing. Topical report, May 1995-July 1996

    SciTech Connect

    Penny, G.S.; Conway, M.W.; Almond, S.W.; Himes, R.; Nick, K.E.

    1996-08-01

    This topical report documents the mechanisms of formation damage following hydraulic fracturing and their impact upon gas well productivity. The categories of damage reviewed include absolute or matrix permeability damage, relative permeability alterations, the damage of natural fracture permeability mechanisms and proppant conductivity impairment. Case studies are reviewed in which attempts are made to mitigate each of the damage types. Industry surveys have been conducted to determine the perceptions of the industry on the topic of formation damage following hydraulic fracturing and to identify key formations in which formation damage is a problem. From this information, technical hurdles and new technology needs are identified and estimates are made of the benefits of developing and applying minimum formation damage technology.

  3. Hydrophobic Organic Compounds in Hydraulic Fracturing Flowback Waters: Identification and Source Apportionment

    NASA Astrophysics Data System (ADS)

    Plata, D.; Shregglman, K.; Elsner, M.; Getzinger, G.; Ferguson, L.; Drollette, B.; Karatum, O.; Nelson, R. K.; Reddy, C. M.

    2014-12-01

    Current hydraulic fracturing technologies rely on organic chemicals to serve multiple critical functions, including corrosion inhibition, in situ gel formation, and friction reduction. While industrial users have disclosed several hundreds of compound and mixture identities, it is unclear which of these are used and where, in what proportion, and with what frequency. Furthermore, while flowback and production waters contain both fracturing additive and geogenic compounds, they may contain potential reaction byproducts as well. Here, we identified several hundred organic compounds present in six hydraulic fracturing flowback waters over the Fayetteville shale. Identifications were made via non-target analysis using two-dimensional gas chromatography with time of flight mass spectrometry for hydrophobic organic compounds and liquid chromatography- orbitrap mass spectrometry. Compound identities were confirmed using purchased standards when available. Using the SkyTruth database and the Waxman list of disclosed compounds, we assigned compounds as either fracturing-fluid-derived or geogenic (or both), or a putative transformation products thereof. Several unreported halogenated compounds were detected, including chlorinated, brominated, and iodated species that have no known natural sources. Control studies indicated that these could not be formed under typical laboratory or field storage conditions, suggesting that halogenation reactions may give rise to novel compounds in the subsurface, presumably via reaction between fracturing fluid additives and shale-derived brines. Further, the six samples were strikingly heterogeneous, reflecting the diversity in fracturing fluid composition and flowback handling procedures at the time of the study.

  4. A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development

    Microsoft Academic Search

    Ahmad Ghassemi

    2003-01-01

    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

  5. Effect of Different Instrumentation Techniques on Vertical Root Fracture Resistance of Endodontically Treated Teeth

    PubMed Central

    Tavanafar, Saeid; Karimpour, Azadeh; Karimpour, Hamideh; Mohammed Saleh, Abdulrahman; Hamed Saeed, Musab

    2015-01-01

    Statement of the Problem Vertical root fractures are catastrophic events that often result in tooth extraction. Many contributing factor are associated with increasing incidence of vertical root fracture. Root canal preparation is one of the predisposing factors which can increase the root susceptibility to vertical fracture. Purpose The aim of this study was to compare the effects of three different instrumentation techniques on vertical root fracture resistance of endodontically treated teeth. Materials and Methods In this study, 120 freshly extracted mandibular premolar teeth of similar dimensions were decoronated and randomly divided into control (n=30), nickel-titanium hand K-file (HF, n=30), BioRaCe rotary file (BR, n=30), and WaveOne reciprocating single-file (WO, n=30) groups. After cleaning and shaping the root canals, AH26 was used as canal sealer, and obturation was completed using the continuous wave technique. The root canals were embedded vertically in standardised autopolymerising acrylic resin blocks, and subjected to a vertical load to cause vertical root fracture. The forces required to induce fractures were measured using a universal testing machine. ANOVA and Tukey’s post-hoc test were used to analyse the data. Results All experimental groups showed statistically significant reductions in fracture resistance as compared with the control group. There was a statistically significant difference between the HF and BR groups. The WO group did not differ significantly from the HF group or the BR group. Conclusion All three instrumentation techniques caused weakening of the structure of the roots, and rendered them susceptible to fracture under lesser load than unprepared roots. The fracture resistance of roots prepared with the single-file reciprocating technique was similar to that of those prepared with NiTi hand and rotary instrumentation techniques.

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

    E-print Network

    Lewallen, Kyle Thomas

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  8. Optimization of hydraulic fracture design - application to a gas storage reservoir

    SciTech Connect

    Balan, B.

    1996-12-31

    A two-step unconventional method that uses neural networks for accurately estimating post fracture deliverability, and genetic algorithms for optimizing the hydraulic fracture design is proposed in this study. The genetic algorithm, being a global search algorithm, was able to find the optimum combination of seventeen frac parameters that maximizes post-frac deliverability of a well. This method has been applied to a large natural gas storage field where accurate post fracture well performance estimates and optimized fractreatment design have become crucial to ensure continued deliverability gains. A database containing basic well information, past fracture designs, and performance history for that field has been developed, without additional cost. The hybrid model was implemented into a user-friendly, Windows95 based, computer program.

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

    NASA Astrophysics Data System (ADS)

    Cai, Zuansi; Ofterdinger, Ulrich

    2014-05-01

    The success of unconventional gas extracted from shale formations (shale gas) over the last decade has changed the energy landscape in the United States. Shale gas rose from 2% of US gas production in 2000 to 30% in 2011, and is projected to rise to more than 50% by 2030. On the global scale, shale gas could increase total natural gas resources by approximately 32%, with an estimate of the total 7,299 trillion cubic feet (~200 trillion cubic meter) technically recoverable gas worldwide. In the UK, onshore shale gas reserve potential was first estimated to be 150 billion cubic meter by the British Geological Survey (BGS) in 2010. A recent study by BGS revised the previous estimates, with best estimate (50% probability) of total in-place gas resource of 37.6 trillion cubic meters in the Bowland Shale across central Britain. However, there are concerns of potential environmental impacts of hydraulic fracturing of the shale formations, particularly those related to water quality, such as gas migration, contaminant transport through induced and natural fractures. To evaluate the potential impact of hydraulically fractured shale on overlying aquifers, we conduct numerical modelling simulations to assess flow and solute transport from a synthetic Bowland Shale over a period of 1000 years. The synthetic fractured shale was represented by a three-dimensional discrete fracture model that was developed by using the data from a Bowland Shale gas exploration in Lancashire, UK. The assessment was carried out to investigate chloride mass fluxes from the fractured Bowland Shale for a range of upward fracture height growths from 200 to 1850 meters, with three sets of hydraulic conductivities over three orders of magnitude for a multi-layered geological system. Of eighteen scenario analyses, the maximum upward mass flux towards the overlying Sherwood Sandstone aquifer is < 0.02 ton Cl-/ yr when a constant chloride concentration of 100 g Cl-/L is applied for the brine in the fractured shale. With this mass flux rate into the fracture area of ~0.75 km2, it is unlikely to create average chloride concentration over the UK maximum concentration level of 188 mg Cl-/L in groundwater, although upward mass flux via fractures could create pollution 'hot spot' areas exceeding this concentration level. The model study also reveals that the upward mass flux is significantly intercepted by the horizontal mass flux within a high permeable layer between the Bowland Shale and its overlying aquifers, preventing further upward flux towards the overlying aquifers.

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

    SciTech Connect

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

    2013-11-19

    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.

  11. Hydraulic fracturing: A proven N.O.R.M. disposal method

    SciTech Connect

    Young, S.C. [Halliburton Energy Services, New Orleans, LA (United States); Chambers, D.G. [Halliburton Energy Services, Lafayette, LA (United States); Woods, S.E.; Abernathy, S.E. [Halliburton Energy Services, Duncan, OK (United States)

    1995-10-01

    Since the discovery that many drill cuttings, scales, sludges, and platings contain elevated amounts of naturally occurring radioactive material (NORM), many companies and regulating authorities have discussed the merits of various disposal methods. This paper covers a process that disposes of NORM and provides isolation of the material from the environment. Disposal of NORM slurry through fracturing an existing depleted sandstone requires careful analysis to optimize a safe and effective design. A radioactivity assay was performed on the NORM before and after slurrification to determine activity concentrations. Tests were conducted on the NORM to proved parameters for the fracture design. The process consists of slurrying the material and keeping the particles suspended in solution until time for well injection. Well injection takes the form of hydraulic fracturing with the material into a deplete zone in the reservoir. Fracturing with the NORM was preceded with a Mini-Frac as a safety precaution to confirm downhole parameters. In conclusion, the philosophy of the process is to take the NORM generated through the exploration and production of oil and gas and place it back into the reservoir from which it came through hydraulic fracturing. This technique is one that helps protect the environment from the possible hazards associated with mismanaged NORM.

  12. Identification of parameters influencing the response of gas storage wells to hydraulic fracturing with the aid of a neural network

    SciTech Connect

    McVey, D.S.; Mohaghegh, S.; Aminian, K.

    1994-12-31

    Performing hydraulic fractures on gas storage wells to improve their deliverability is a common practice in the eastern part of the United States. Most of the fields in this part of the country being used for storage are old. Reservoir characteristic data necessary for most reservoir studies and hydraulic fracture design and evaluation are scarce for these old fields. This paper introduces a new methodology by which parameters that influence the response of gas storage wells to hydraulic fracturing may be identified in the absence of sufficient reservoir data. Control and manipulation of these parameters, once identified correctly, could enhance the outcome of frac jobs in gas storage fields. The study was conducted on a gas storage field in the Clinton formation of Northeastern Ohio. It was found that well performance indicators prior to a hydraulic fracture play an important role in how good the well will respond to a new frac job. Several other important factors were also identified.

  13. Results of a 1995 hydraulic fracturing survey and a comparison of 1995 and 1990 industry practices

    SciTech Connect

    Carter, R.H.; Holditch, S.A.; Wolhart, S.L.

    1996-12-31

    This paper presents the results of a hydraulic fracturing survey conducted in 1995 on behalf of the Gas Research institute (GRI). The purpose of the survey was to determine the types of formations that are normally fracture treated; gather data on the fracture treatments that are normally pumped; determine the level of data collection being conducted in the field; determine the level of data analysis being conducted in the office and the field; solicit opinions on the level of technology required to obtain an accurate analysis for fracture treatments; solicit opinions of the limitations of current technology; determine what costs operators could justify to analyze fracture treatment data and obtain ideas on new areas of research. Data gathered in the survey included respondents company size (major, large/small independent, service company or consultant), geographical area of operation, well depths and permeabilities, fracture treatment size, proppant type and volume, level of detail in data gathering, fracture treatment design and real-time analysis. The 1995 data were compared to a similar survey conducted in 1990 by GRI to determine technology trends.

  14. Analysis of power-law self-similar solutions to the problem of hydraulic fracture crack formation

    Microsoft Academic Search

    N. N. Smirnov; V. R. Tagirova

    2007-01-01

    The problem of hydraulic fracture crack propagation in a porous medium is studied in the approximation of small crack opening\\u000a and the inertialess flow of an incompressible Newtonian hydraulic fracturing fluid inside the crack. A one-parameter family\\u000a of power-law self-similar solutions is considered in order to determine the crack width evolution, the fluid velocity in the\\u000a crack, and the seepage

  15. Gaussian-Beam S-wave Polarization-based Location Method for Hydraulic Fracturing Induced Seismicity

    Microsoft Academic Search

    X. Zhao; D. Collins; P. Young

    2008-01-01

    We propose a new method to locate hydraulic fracturing induced seismicity using three-component waveforms based on the Gaussian-beam S-wave polarization modified from Rentsch et al. (Geophysics, 2007) who used P-wave polarization. As a highly automated method, the method only requires a window around the S-wave peak amplitude and does not depend on arrival-time picking as used in standard location routines.

  16. Identification of parameters influencing the response of gas storage wells to hydraulic fracturing with the aid of a neural network

    SciTech Connect

    McVey, D.S. [East Ohio Gas Co., North Canton, OH (United States); Mohaghegh, S.; Aminian, K.; Ameri, S. [West Virginia Univ., Morgantown, WV (United States)

    1996-04-01

    Performing hydraulic fractures on gas storage wells to improve their deliverability is a common practice in the eastern part of the US. Most fields used for storage in this region are old, and the reservoir characteristic data necessary for most reservoir studies and hydraulic fracture design and evaluation are scarce. This paper introduces a new method by which parameters that influence the response of gas storage wells to hydraulic fracturing may be identified in the absence of sufficient reservoir data. Control and manipulation of these parameters, once identified correctly, could enhance the outcome of frac jobs in gas storage fields. The authors conducted the study on a gas storage field in the Clinton formation of northeastern Ohio. They found that well-performance indicators before a hydraulic fracture play an important role in how good the well will respond to a new frac job. They also identified several other important factors. The identification of controlling parameters serves as a foundation for improved frac job design in the fields where adequate engineering data are not available. Another application of this type of study could be the enhancement of selection criteria among the candidate wells for hydraulic fracturing. To achieve the objective of this study, the authors designed, trained, and applied an artificial neural network. The paper will discuss the results of the incorporation of this new technology in hydraulic fracture design and evaluation.

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

    NASA Astrophysics Data System (ADS)

    Boudet, H. S.

    2013-12-01

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

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

    PubMed

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

    2015-01-01

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

  19. Recharge and pumping hydraulics in a till drumlin above fractured bedrock (Massachusetts, USA)

    NASA Astrophysics Data System (ADS)

    Ostendorf, David W.; Lukas, William G.; Rotaru, Camelia

    2015-02-01

    Recharge and pumping hydraulics of a till-mantled bedrock are analyzed with existing closed-form theory and 12 years of monthly water levels in cluster wells from Scituate Hill, a glacial till drumlin in eastern Massachusetts (USA). The weathered brown till atop Scituate Hill is an unconfined aquifer, delivering steady recharge and a seasonally varying recharge-head fluctuation to the unweathered gray till aquitard beneath it. The water-table fluctuations generate no seasonally varying flow field in the gray till, due to the relatively low hydraulic diffusivity of the brown till. Nearby irrigation pumps drilled into the underlying Dedham Granite in 2011 have introduced seasonal drawdown, and the gray till leaks into the fractured bedrock aquifer. The leakage reflects the moderate diffusivity of the gray till and the relatively high hydraulic diffusivity of the fractured bedrock. Both seasonal disturbances are mildly attenuated across the gray till, so that the Dedham Granite senses recharge, while the water table in Scituate Hill is drawn down by irrigation pumping. Steady and seasonal gray till data are accordingly used to calibrate the transmissivity and storativity of the fractured bedrock and specific yield of the brown till, with physically plausible values.

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

    PubMed

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

    2015-02-01

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

  1. Stimuli Responsive/Rheoreversible Hydraulic Fracturing Fluids for Enhanced Geothermal Energy Production(Part II)

    NASA Astrophysics Data System (ADS)

    Bonneville, A.; Jung, H. B.; Shao, H.; Kabilan, S.; Um, W.; Carroll, K. C.; Varga, T.; Suresh, N.; Stephens, S.; Fernandez, C. A.

    2014-12-01

    We have used an environmentally friendly and recyclable hydraulic fracturing fluid - diluted aqueous solutions of polyallylamine or PAA - for reservoir stimulation in Enhanced Geothermal System (EGS). This fluid undergoes a controlled and large volume expansion with a simultaneous increase in viscosity triggered by CO2 at EGS temperatures. We are presenting here the results of laboratory-scale hydraulic fracturing experiment using the fluid on small cylindrical rock cores (1.59 cm in diameter and 5.08 cm in length) from the Coso geothermal field in California. Rock samples consisted of Mesozoic diorite metamorphosed to greenschist facies. The experiments were conducted on 5 samples for realistic ranges of pressures (up to 275 bar) and temperatures (upt to 210 °C) for both the rock samples and the injected fluid. After fracturation, cores were subjected to a CO2 leakage test, injection of KI solution, and X-ray microtomography (XMT) scanning to examine the formation and distribution of fractures. The design and conduct of these experiments will be presented and discussed in details. Based on the obtained XMT images, Computational Fluid Dynamics (CFD) simulations were then performed to visualize hydraulic fractures and compute the bulk permeability. OpenFOAM (OpenCFD Ltd., Reading, UK), was used to solve the steady state simulation. The flow predictions, based upon the laminar, 3-D, incompressible Navier-Stokes equations for fluid mass and momentum, show the remarkable stimulation of the permeability in the core samples and demonstrate the efficiency of such a CO2 triggered fluid in EGS.

  2. 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

    Paris-Sud XI, Université de

    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

  3. Field applications of cryogenic nitrogen as a hydraulic-fracturing fluid

    SciTech Connect

    NONE

    1998-03-01

    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.

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

    SciTech Connect

    David S. Schechter

    2004-10-10

    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.

  5. Hydraulic fracturing research in east Texas; Third GRI staged field experiment

    SciTech Connect

    Robinson, B.M. (S.A. Holditch and Associates, Inc. (US))

    1992-01-01

    This paper presents results from results from research conducted on the third Gas Research inst. (GRI) staged field experiment (SFE) well. Research well SFE No. 3 was drilled as part of a field-based research program conducted in east Texas during the past 7 years. Most of the work before SFE No. 3 involved the Travis Peak formation; however, the Cotton Valley sandstone was the primary research target for this well. SFE no. 3 is the last in a series of research wells planned for east Texas. A fourth SFE is being conducted in the Frontier formation of southwestern Wyoming. Data on SFE wells are collected from whole cores, openhole geophysical logs, in-situ stress measurements, production and pressure-transient tests, fracture stimulation treatments, fracture-diagnostic measurements, and postfracture performance tests. Test data then are analyzed by research scientists, geologists, and engineers to describe the reservoir and hydraulic fracture fully.

  6. HYFRAC3D. Finite Element Code for 3D-Hydraulic Fracture Propagation Equations (Mult-Layer)

    Microsoft Academic Search

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

    1988-01-01

    HYFRAC3D is a finite element program for simulation of three-dimensional fracture geometries with a two-dimensional planar solution. The model predicts the height, width and winglength over time for a hydraulic fracture propagating in a multi-layered system of rock with variable fluid flow and rock mechanics properties.

  7. HYFRAC3D. Finite Element Code For 3D-Hydraulic Fracture Propagation Equations (Mult-Layer)

    Microsoft Academic Search

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

    1988-01-01

    HYFRAC3D is a finite element program for simulation of three-dimensional fracture geometries with a two-dimensional planar solution. The model predicts the height, width and winglength over time for a hydraulic fracture propagating in a multi-layered system of rock with variable fluid flow and rock mechanics properties.

  8. Analyzing pumped-well impeller logs to ascertain vertical hydraulic conductivity variations

    NASA Astrophysics Data System (ADS)

    Parker, A. H.; West, J.; Odling, N. E.; Bottrell, S. H.

    2007-12-01

    Horizontal variations in the hydraulic conductivity of aquifers are generally well characterized through simple pump test analyses. However, vertical variations are often poorly understood and misrepresented in the regional models used by regulatory bodies and water companies. Understanding these is key for predicting flow paths and hence the behavior of contaminants in the aquifer that might present a risk to public drinking water supplies. Traditionally, packer tests were used to characterize these variations, but they can be time consuming and costly to perform. However, other techniques have been developed which can quantify these variations, including impeller logging. This study aims to present new, more rigorous methods of analyzing impeller flow log data. Impeller logs were taken under pumped conditions in open wells in a chalk aquifer located in N. England. Theoretically, hydraulic conductivity can be obtained from the gradient in flow rate with depth. However, data are typically noisy due to turbulent flow and hole diameter variations with depth; so directly converting the flow rate gradient to hydraulic conductivity leads to rapid non-physical variation and negative hydraulic conductivity values. Correcting for hole diameter variations using caliper logs proved difficult due to phenomena such as jetting, whereby when the water enters a widening, it does not instantly slow down. In order to obtain more realistic hydraulic conductivity profiles, we firstly tried a data smoothing algorithm, but this approach distorted the data and still gave an unacceptable noise level. Instead, a layered modeling approach has been developed. A hydraulic conductivity profile consisting of a discrete number of uniform layers is constructed, and layer thicknesses and hydraulic conductivities are varied until a satisfactory fit to the observed flow log is achieved. Results from field sites on the confined Chalk aquifer of East Yorkshire in the United Kingdom showed good correlation to packer test analysis. The absence of significant ambient flows at this test site made the final analysis relatively simple. By testing boreholes across the aquifer a pattern of hydraulic conductivity variation with depth can be established, and compared to the proposed geological and climatic reasons for the variations' existence.

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

    E-print Network

    Moreno, Jose A

    2014-08-12

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

  10. Simulating the hydraulic stimulation of multiple fractures in an anisotropic stress field applying the discrete element method

    NASA Astrophysics Data System (ADS)

    Zeeb, Conny; Frühwirt, Thomas; Konietzky, Heinz

    2015-04-01

    Key to a successful exploitation of deep geothermal reservoirs in a petrothermal environment is the hydraulic stimulation of the host rock to increase permeability. The presented research investigates the fracture propagation and interaction during hydraulic stimulation of multiple fractures in a highly anisotropic stress field. The presented work was conducted within the framework of the OPTIRISS project, which is a cooperation of industry partners and universities in Thuringia and Saxony (Federal States of Germany) and was funded by the European Fond for Regional Development. One objective was the design optimization of the subsurface geothermal heat exchanger (SGHE) by means of numerical simulations. The presented simulations were conducted applying 3DEC (Itasca™), a software tool based on the discrete element method. The simulation results indicate that the main direction of fracture propagation is towards lower stresses and thus towards the biosphere. Therefore, barriers might be necessary to limit fracture propagation to the designated geological formation. Moreover, the hydraulic stimulation significantly alters the stresses in the vicinity of newly created fractures. Especially the change of the minimum stress component affects the hydraulic stimulation of subsequent fractures, which are deflected away from the previously stimulated fractures. This fracture deflection can render it impossible to connect all fractures with a second borehole for the later production. The results of continuative simulations indicate that a fracture deflection cannot be avoided completely. Therefore, the stage alignment was modified to minimize fracture deflection by varying (1) the pauses between stages, (2) the spacing's between adjacent stages, and (3) the angle between stimulation borehole and minimum stress component. An optimum SGHE design, which implies that all stimulated fractures are connected to the production borehole, can be achieved by aligning the stimulation borehole at an angle of 45° to the minimum stress component. Furthermore, longer pauses between injection stages and higher spacing between stages promote more consistent fracture geometries. The simulation results indicate that fractures tend to propagate in random directions away from the stress shadows of existing fractures, even for a stage spacing of 200 m. This fracture deflection may result in undesirable fracture propagation directions or produce shortcuts between fracture stages. A careful planning of the stage alignment seems the most promising procedure to counteract/control fracture deflection.

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

    NASA Astrophysics Data System (ADS)

    Fan, Juncai

    The main topic of this thesis is the modeling of fracture of steel pipes and stratified rocks. The study of fracture of steel pipes suggests a way to protect materials from a premature failure. On the other hand, the study of fracture of stratified rocks helps to find a way to optimize hydraulic fractures. Firstly, the fracturing process that happened on the surface of high-pressure pipelines was investigated under the consideration of the coupling of stress and aggressive environment, Stress Corrosion Cracking (SCC). SCC colony evolution is a major cause of premature pipe failures. Deterministic and stochastic features in SCC colony formation were discussed. A reasonable agreement between modeling results and the observations was achieved. The hydraulic fracturing in stratified porous rock is the second topic of the study. Mass conservation and energy conservation laws were employed to build the governing equations of the hydraulic fracturing process. The Griffith criterion was used to control the direction of fracture propagation. Bias propagation was realized based mainly on the anisotropic model of fracture toughness. Using the proposed model, the polyaxial cell test results were successfully simulated.

  12. Hydraulics.

    ERIC Educational Resources Information Center

    Decker, Robert L.; Kirby, Klane

    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)…

  13. Performance of hydraulic fracturing and matrix acidizing in horizontal wellbores -- Offshore Qatar

    SciTech Connect

    Edwards, M.G.R.; Pongratz, R.

    1995-11-01

    Considerable debate in the Middle East has centered upon what was previously felt to be two separate methods of enhancing revenues and daily production; hydraulic fracturing and horizontal drilling. In an effort to maximize return on investment, these two issues have been successfully combined in other areas of the world. In order to establish the suitability of this technology in this area, two horizontal wells with over 3,050m (10,000ft) of lateral section were drilled into the Cretaceous Kharaib formation, overlying the North Field, Offshore Qatar. A massive stimulation program was performed in order to evaluate the most feasible stimulation method from both a technical and economical perspective for further field development considerations.Three propped hydraulic fracturing treatments were performed using 183, 500kg (403, 700lb) of 20/40 mesh sand, and seventeen acid matrix treatments placing over 3,217,250l (850,000gals) of HCL into the lateral sections of both wells. This paper describes the performance, operation and logistical support required to complete this offshore operation with join a minimal time frame. The use of a mobile offshore jack-up platform, whereby a land based fracturing spread was placed onto the deck of a converted drilling rig is described.

  14. Tracer studies and hydraulic behaviour of planted and un-planted vertical-flow constructed wetlands.

    PubMed

    Cota, R S; von Sperling, M; Penido, R C S

    2011-01-01

    The aim of this research was to assess the hydraulic behaviour of three intermittently-fed vertical flow wetland units operated in parallel, designed for the treatment of raw wastewater generated in the city of Belo Horizonte, Brazil. The system was designed to serve 100 PE (-1 m2/PE). The first filter was planted with cattail (Typha latifolia), the second with Tifton-85 (Cynodon spp.) and the third was maintained without plants (control unit). NaCl tracer tests were conducted to determine the residence time distribution. The tests were done with water when the system was unused (clean media) and also after an 11-month operation period with wastewater (used media), using two different dosing regimes (lower and higher frequency). Results showed a strong tendency towards the hydraulic completely mixed regime. A great dispersion in the units and the presence of short circuiting and dead zones were observed. The unsaturated condition in a large volume of the filter, even during the draining stage, was confirmed for the three units. The dosing regime, the resting period duration, the age of the filter and the presence of plants were found to influence the hydraulic processes in the units. PMID:22214051

  15. Innovative Field Methods for Characterizing the Hydraulic Properties of a Complex Fractured Rock Aquifer (Ploemeur, Brittany)

    NASA Astrophysics Data System (ADS)

    Bour, O.; Le Borgne, T.; Longuevergne, L.; Lavenant, N.; Jimenez-Martinez, J.; De Dreuzy, J. R.; Schuite, J.; Boudin, F.; Labasque, T.; Aquilina, L.

    2014-12-01

    Characterizing the hydraulic properties of heterogeneous and complex aquifers often requires field scale investigations at multiple space and time scales to better constrain hydraulic property estimates. Here, we present and discuss results from the site of Ploemeur (Brittany, France) where complementary hydrological and geophysical approaches have been combined to characterize the hydrogeological functioning of this highly fractured crystalline rock aquifer. In particular, we show how cross-borehole flowmeter tests, pumping tests and frequency domain analysis of groundwater levels allow quantifying the hydraulic properties of the aquifer at different scales. In complement, we used groundwater temperature as an excellent tracer for characterizing groundwater flow. At the site scale, measurements of ground surface deformation through long-base tiltmeters provide robust estimates of aquifer storage and allow identifying the active structures where groundwater pressure changes occur, including those acting during recharge process. Finally, a numerical model of the site that combines hydraulic data and groundwater ages confirms the geometry of this complex aquifer and the consistency of the different datasets. The Ploemeur site, which has been used for water supply at a rate of about 106 m3 per year since 1991, belongs to the French network of hydrogeological sites H+ and is currently used for monitoring groundwater changes and testing innovative field methods.

  16. Evaluation of RA tracer surveys and hydraulic fracture ID logs in the Antrim shale. Topical report, June-August 1993

    SciTech Connect

    Reeves, S.R.; Wicks, D.E.

    1993-11-01

    The report summarizes the results of five radioactive tracer surveys, one comparison of pre- and post-stimulation fracture identification logs, and presents stress/mechanical properties information from three wells in the Antrim Shale of the Michigan Basin. The purpose of this work, based on wells located in Section 29, 31 and 32 of T3ON, R1W, and in Section 17 of T29N, R1W, was to provide insights into fracture growth behavior in the Antrim Shale. While highly interpretive and conflicting at times, the data seem to suggest (1) that both the Lachine and Norwood shales are fractured during single-stage treatements, (2) that the Paxton appears to be a good fracture barrier, (3) fracture height growth into the Ellsworth is possible when the Lachine is stimulated, and (4) discreet vertical intervals of fracturing occur in the Lachine as opposed to a single, continuous vertical fracture over the entire interval.

  17. The Role of Toxicological Science in Meeting the Challenges and Opportunities of Hydraulic Fracturing

    PubMed Central

    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

    2014-01-01

    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

  18. Pumping-Test Evaluation of Fault-Zone Hydraulic Properties in a Fractured Sandstone

    NASA Astrophysics Data System (ADS)

    Johnson, N. M.

    2014-12-01

    Subzones of both reduced and enhanced permeability are often ascribed to fault zones, consistent with a fault-core/damage-zone conceptualization, with associated implications for assessing potential contaminant transport. Within this context, a 31-day pumping test was conducted in relation to a relatively minor, 2000 m long fault zone cutting fractured Cretaceous sandstone interbedded with siltstone and shale at a groundwater remediation site in the Simi Hills of southern California during March-April 2013. Our objective was to evaluate the potential hydrogeologic influence of the fault zone on groundwater movement across and along it by observing the spatial patterns of drawdown and estimated hydraulic properties. A 122 m deep open borehole was pumped at a constant rate of approximately 112 L/min while monitoring hydraulic heads in 14 observation wells, two completed with multi-level systems, within 750 m of the pumping well. Hydraulic heads were monitored for more than 9 months before, during, and after the test. Prior to the test, we used the site's three-dimensional, equivalent-porous-media groundwater flow model to anticipate the potential response of alternative fault-zone permeability structures. The results suggest that the fault zone may be slightly more permeable (by a factor of about 2 or less) and less confined than the fractured sandstone away from the fault, and is not a significant barrier to groundwater flow across it. Within the areal extent of observed drawdown, the site's hydrostratigraphic structures exhibited a relatively greater hydraulic influence. The pattern and magnitude of observed drawdown lie within the range of pre-test model simulations, and the test results are now being used to revise and recalibrate the model.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  1. Comparison study of hydraulic fracturing models -- Test case: GRI Staged Field Experiment No. 3

    SciTech Connect

    Warpinski, N.R.; Moschovidis, Z.A.; Parker, C.D.; Abou-Sayed, I.S.

    1992-12-31

    This study is a comparison of hydraulic-fracture models run using test data from the GRI Staged Field Experiment No. 3. Models compared include 2-D, pseudo-3-D, and 3-D codes, run on up to eight different cases. Documented in this comparison are the differences in length, height, width, pressure and efficiency. The purpose of this study is to provide the completions engineer a practical comparison of the available models so that rational decisions can be made about which model(s) is optimal for a given application.

  2. Hydraulic fracturing of the Devonian Shale with a non-damaging fluid

    SciTech Connect

    Mazza, R.L.; Gehr, J.B. [Petroleum Consulting Services, Canton, OH (United States)

    1992-05-01

    To demonstrate within the Appalachian Basin the use of liquid carbon dioxide as a medium for hydraulically fracturing the Devonian Shale, while transporting sand as a proppant. The project scope includes candidate wells in up to five states, Kentucky, Ohio, Tennessee, Virginia, and West Virginia; To compare and rank the gas production responses from wells treated with liquid CO{sub 2} with other types of treatments (shooting, water based, nitrogen, etc.). These demonstrations will involve two phases: Phase I - Up to fifteen wells in up to five target areas. (Aug 93) Phase II - Up to nine wells in up to three target areas [seventeen months].

  3. Comparison study of hydraulic fracturing models -- Test case: GRI Staged Field Experiment No. 3

    SciTech Connect

    Warpinski, N.R. (Sandia National Lab., Albuquerque, NM (United States)); Moschovidis, Z.A. (Amoco Production Co., Tulsa, OK (United States)); Parker, C.D. (Conoco Inc., Houston, TX (United States)); Abou-Sayed, I.S.

    1994-02-01

    This study is a comparison of hydraulic fracture models run using test data from the GRI Staged Field Experiment No. 3. Models compared include 2D, pseudo-3D, and 3D codes, run on up to eight different cases. Documented in this comparison are the differences in length, height, width, pressure, and efficiency. The purpose of this study is to provide the completions engineer with a practical comparison of the available models so that rational decisions can be made as to which model is optimal for a given application.

  4. Stress wave propagationin the site 12 hydraulic/explosive fracturing experiment

    SciTech Connect

    Boade, R. R.; Reed, R. P.

    1980-05-01

    The Site 12 experiment was a heavily instrumented field event performed to examine the hydraulic/explosive fracturing concept for preparing an underground oil shale bed for true in situ processing. One of the key phases of this fracturing concept is the blasting operation which involves the insertion and detonation of slurry explosive in a pre-formed system of hydrofractures. To obtain a sound understanding of the nature of the blasting operations, a rather extensive array of stress gages, accelerometers, and time-of-arrival gages was installed in the rock mass in the vacinity of the explosive to monitor the dynamic events initiated by the detonation. These gages provided considerable amounts of information which were useful in evaluating overall results of the experiment. Details of the gage array, of the data, of analysis methods, and of the results and conclusions are considered in the report.

  5. In-situ stress profiling and prediction of hydraulic fracture azimuth for the west Texas Canyon Sands formation

    SciTech Connect

    Miller, W.K. II (NSI Technologies Inc., Tulsa, OK (United States)); Peterson, R.E. (CER Corp., Las Vegas, NV (United States)); Harrison, C.W. (AGIP Petroleum Co., Houston, TX (United States)); Stevens, J.E.; Lackey, C.B.

    1994-08-01

    This paper presents results of hydraulic fracture azimuth and in-situ stress measurements for two wells in the west Texas Canyon Sands formation. The paper gives information for designing infill drilling patterns and improving fracture treatment designs. Eight techniques were applied to measure fracture azimuth; the results from each are discussed. In-situ stress was measured in 12 intervals, and the results were used to calibrate long-spaced digital sonic logs. This paper also discusses the application of calibrated stress to fracture treatment design.

  6. Hydraulic Fracture Measurements at Site C0009 of IODP Expedition 319, NanTroSEIZE

    NASA Astrophysics Data System (ADS)

    Kano, Y.; Ito, T.; Lin, W.; Flemings, P. B.; Boutt, D. F.; Doan, M.; McNeill, L. C.; Byrne, T.; Saffer, D. M.; Araki, E.; Eguchi, N. O.; Takahashi, K.; Toczko, S.; Scientists, E.

    2009-12-01

    The drilling vessel Chikyu completed the first riser-drilling in IODP history to a depth of 1603 mbsf (meter below seafloor) at Site C0009 in the landward Kumano forearc basin in the Nankai convergent margin, Japan.To measure in situ stress we performed two types of hydraulic fracturing: 1) as part of routine drilling operations, we estimated least principle stress from a leak off test (LOT); and 2) we used Schlumberger’s dual wireline packer, the Modular Dynamics Tester (MDT). Two LOT’s were performed at the base of 20 inch casing (703.9 mbsf) as a part of standard drilling operations; the outer annulus was closed by the blowout preventor (BOP), fluid was pumped at a constant rate of 2.3 m3/s, and pressure was measured at the cement pumps. The leak-off pressures were interpreted to lie at the break in slope in a graph of pressure vs volume-pumped. These values were found to be 30.22 and 30.25 MPa. These leak off pressure is interpreted to record fluids entering hydraulic fractures and is approximately the the least principal stress. There is considerable uncertainty in picking the slopes of the lines to determine the least principal stress (S3). The MDT dual packer tests were carried out at depth of 873.7 and 1532.7 mbsf. The dual packer module isolates a 1-m section of the borehole for testing. Zones free from pre-existing fractures and with near circular hole shape were chosen for the stress measurements. In the HF test at 873.7 m, the pressure cycle was repeated 5 times maintaining flow rate of 20 cm3/s. Periods of each cycles were 80-300 s. We determined the instantaneous shut in pressure to be 34.8 MPa. In the test at 1532.7 m, only one pressure cycle with a flow rate of 20 cm3/s was maintained, which yielded an instantaneous shut in pressure of 41.6 MPa. We interpret the shut-in pressure to record the least principal stress (S3). We do not know the orientation of fractures which were induced or activated by hydraulic fracturing, because no borehole images were taken after the HF tests. S3 at both test depths is less than Sv (the overburden stress). The stress ratio, K = (S3-Ph)/(Sv-Ph) where Ph is the hydrostatic pressure (calculated assuming a pore fluid density of 1023 kg/m3), was 0.44 for LOT and were 0.82 and 0.44, for MDT.

  7. The influence of fluid properties on the success of hydraulic fracturing operations

    SciTech Connect

    Power, D.J.; Boger, D.V. [Univ. of Melbourne, Victoria (Australia); Paterson, L.

    1994-12-31

    Hydroxypropylguar based fluids are the most commonly used fluids for hydraulic fracturing. Through the addition of borate ions the polymer present in the fluid can crosslink to form a high viscosity gel. Prior to placement in the fracture the fluid is required to have a low viscosity to minimize friction losses in the tubular goods. A high viscosity fluid is required in the fracture for several reasons, primarily to suspend the proppant and to minimize fluid loss into the formation. This paper describes a new method which can be used to model the gelation reaction of crosslinking fluids. By modeling the dynamic properties of the fluid it is possible to predict the physical state of the fluid at any time during a fracturing treatment. Small amplitude oscillatory measurements are applied to fluid samples in a cone-and-plate geometry. The change in the dynamic properties with time can be fitted to a simple model which can then be used to determine the gel time for the fluid. Methods used to distinguish between the liquid and gel state are also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  9. Estimating hydraulic conductivity of fractured rocks from high-pressure packer tests with an Izbash's law-based empirical model

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Feng; Hu, Shao-Hua; Hu, Ran; Zhou, Chuang-Bing

    2015-04-01

    High-pressure packer test (HPPT) is an enhanced constant head packer test for characterizing the permeability of fractured rocks under high-pressure groundwater flow conditions. The interpretation of the HPPT data, however, remains difficult due to the transition of flow conditions in the conducting structures and the hydraulic fracturing-induced permeability enhancement in the tested rocks. In this study, a number of HPPTs were performed in the sedimentary and intrusive rocks located at 450 m depth in central Hainan Island. The obtained Q-P curves were divided into a laminar flow phase (I), a non-Darcy flow phase (II), and a hydraulic fracturing phase (III). The critical Reynolds number for the deviation of flow from linearity into phase II was 25-66. The flow of phase III occurred in sparsely to moderately fractured rocks, and was absent at the test intervals of perfect or poor intactness. The threshold fluid pressure between phases II and III was correlated with RQD and the confining stress. An Izbash's law-based analytical model was employed to calculate the hydraulic conductivity of the tested rocks in different flow conditions. It was demonstrated that the estimated hydraulic conductivity values in phases I and II are basically the same, and are weakly dependent on the injection fluid pressure, but it becomes strongly pressure dependent as a result of hydraulic fracturing in phase III. The hydraulic conductivity at different test intervals of a borehole is remarkably enhanced at highly fractured zone or contact zone, but within a rock unit of weak heterogeneity, it decreases with the increase of depth.

  10. Hydraulics.

    ERIC Educational Resources Information Center

    Engelbrecht, Nancy; And Others

    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…

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

    NASA Astrophysics Data System (ADS)

    Hitchens, A.; Knee, K.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

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

    SciTech Connect

    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

    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.

  14. Hydraulic fracturing for control of sand production and asphaltene deposition in deep hot wells

    SciTech Connect

    Ortega, L.; Brito, L.; Ben-Naceur, K.

    1996-12-31

    The North of Monagas giant field in Venezuela has been produced since the late 80-s. Depth ranges from 12000 to 20000 ft (3,600 to 6,000 in). Wells in the field have experienced early in the production cycle both problems of sand production and asphaltene flocculation. A multi-disciplinary team was created to define ways to optimize production from the field The paper first addresses the methodology used to identify the source of the sanding problem, including extensive mechanical analysis of the formation, with tri-axial testing and sanding critical flow gradient analysis. The effectiveness of the initial strategies of optimization of choke size, and selection of perforated intervals and gun sizes is evaluated. The onset of asphaltene deposition was analyzed, and it was determined that most occurring problems were related to drilling and production practices. To solve both problems, by modifying pressure drop and flow profiles, a hydraulic fracturing strategy was implemented in the field. Special care was given to the particular well conditions (close-by dual tubing completion, with potential risk of communication, thick and multi-layered geometry), in addition to expected high treating pressures and sensitivity of formation fluids to thermal shocks. A detailed pre- and post-fracturing well testing procedure was adopted which allows for an optimization of the fracture length, and comparison of results with predictions. Prior to the main fracture, calibration treatments were performed; calculated fracture heights were compared to the ones determined from temperature logs. A new technique to determine permeability from mini-fracs using the theory of impulse testing was also applied. Finally, production logging after the frac and a build-up were used to assess the validity of the predictions.

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

    SciTech Connect

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

    1980-08-01

    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.

  16. Proppant backproduction during hydraulic fracturing -- A new failure mechanism for resin-coated proppants

    SciTech Connect

    Vreeburg, R.J.; Roodhart, L.P.; Davies, D.R.; Penny, G.S. (STIM-LAB Inc., Duncan, OK (United States))

    1994-10-01

    Backproduction of proppant from hydraulically fractured wells, particularly those completed in the northern European Rotliegend formation, is a major operational problem, necessitating costly and manpower-intensive surface-handling procedures. Further, the development of unmanned platform operations offshore, required in today's economic climate, is impossible as long as this problem remains unsolved. The most cost-effective potential solution to this problem is provided by curable resin-coated proppant (RCP), which consolidates in the fracture. Early field trials with RCP's, however, were not completely effective in stopping the backproduction of proppant. Typically, some 10% of the total volume of RCP placed in the fracture was backproduced. The authors performed a laboratory study to help clarify the effect of curing temperature, water production rate, proppant size, and stress cycling on the integrity of RCP packs. The experiments confirmed the field experience that stress cycling has a dramatic effect on proppant backproduction of commercial RCP packs. The number of applied stress cycles (i.e., the number of times the well is shut in) and the initial RCP pack strength appear to be the dominant factors that govern proppant backproduction. Dedicated experiments are therefore required to evaluate the use of RCP's to eliminate proppant backproduction for a particular field application.

  17. Use of hydraulic fracturing to enhance soil vapor extraction - a case study

    SciTech Connect

    Baker, J.E.; Wells, S.L. [Golder Applied Technologies, Atlanta, GA (United States)

    1995-12-31

    Many environmental remediation activities can be cost effectively implemented through the use of soil vapor extraction. While this approach has been shown to work well in relatively high permeability soils, it is much less effective in low permeability silts and clays. The low permeability nature of these soils makes the flow of air required to remove volatile organic vapors difficult, if not impossible. Hydraulic soil fracturing, a modification of petroleum engineering technology to the environmental field, is a viable technique for overcoming this difficulty. The process involves injecting, under pressure, a high viscosity fluid which serves as the carrier for a sand propant. Enzymes which are mixed with the fluid cause the fracturing fluid to revert to a low permeability, allowing it to be pumped out, leaving a series of high permeability sand lenses. Several such lenses are injected at the site of each well, allowing efficient injection and/or extraction of vapors from the soil mass. The details of the fracture design and the results of the remedial action are presented.

  18. Constant rate solutions for a fractured well with an asymmetric fracture

    Microsoft Academic Search

    Sergio Berumen; Djebbar Tiab; Fernando Rodriguez

    2000-01-01

    This paper presents solutions for the pressure response on hydraulically fractured wells flowing at constant flow rate through an asymmetric vertical fracture. The pressure behavior of wells intercepting asymmetric fractures of both infinite and finite conductivity was investigated by solving numerically and analytically the mathematical model. The new solutions developed for the dimensionless wellbore pressure under production at constant flow

  19. A Review of Hydraulic Fracture Models and Development of an Improved Pseudo3D Model for Stimulating Tight Oil\\/Gas Sand

    Microsoft Academic Search

    M. M. Rahman; M. K. Rahman

    2010-01-01

    Many injection\\/production wells have been hydraulically fractured to enhance injectivity\\/productivity. Various engineering models for fracture geometry have been developed, which define the propagation of a fracture with time and wellbore treatment pressure. These models combine with elasticity, fluid flow, material balance, and propagation criterion\\/in-situ stresses. When this combination describes the fracture dimensions, the fracture-geometry can be of two-dimensional (2D) and

  20. 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

    Chiao, Jung-Chih

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

  1. Simulation assessment of the direct-push permeameter for characterizing vertical variations in hydraulic conductivity

    USGS Publications Warehouse

    Liu, Gaisheng; Bohling, G.C.; Butler, J.J., Jr.

    2008-01-01

    [1] The direct-push permeameter (DPP) is a tool for the in situ characterization of hydraulic conductivity (K) in shallow, unconsolidated formations. This device, which consists of a short screened section with a pair of pressure transducers near the screen, is advanced into the subsurface with direct-push technology. K is determined through a series of injection tests conducted between advancements. Recent field work by Butler et al. (2007) has shown that the DPP holds great potential for describing vertical variations in K at an unprecedented level of detail, accuracy and speed. In this paper, the fundamental efficacy of the DPP is evaluated through a series of numerical simulations. These simulations demonstrate that the DPP can provide accurate K information under conditions commonly faced in the field. A single DPP test provides an effective K for the domain immediately surrounding the interval between the injection screen and the most distant pressure transducer. Features that are thinner than that interval can be quantified by reducing the vertical distance between successive tests and analyzing the data from all tests simultaneously. A particular advantage of the DPP is that, unlike most other single borehole techniques, a low-K skin or a clogged screen has a minimal impact on the K estimate. In addition, the requirement that only steady-shape conditions be attained allows for a dramatic reduction in the time required for each injection test. Copyright 2008 by the American Geophysical Union.

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

    SciTech Connect

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

    2010-05-01

    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.

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

    PubMed

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

    2015-02-01

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

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

    Microsoft Academic Search

    Damien Skinner; Graham Heinson

    2004-01-01

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

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

    Microsoft Academic Search

    Wijesinghe

    1987-01-01

    Hydraulic fractures created in oil and gas bearing rock formations can be made to propagate for a limited time at approximately constant height if favorable stress, deformation modulus or fracture toughness barriers to height growth exist and if the fracture design is suitably optimized to exploit these favorable conditions and reduce height growth. In this report, a unified theoretical formulation

  6. Hydraulics.

    ERIC Educational Resources Information Center

    Decker, Robert L.

    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,…

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

    PubMed

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

    2013-01-01

    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

  8. Hydraulic fracturing of the Devonian Shale with a non-damaging fluid

    SciTech Connect

    Mazza, R.L.; Gehr, J.B.

    1992-07-01

    The objectives of this project are: (1) To demonstrate within the Appalachian Basin the use of liquid carbon dioxide (CO{sub 2}) as a medium for hydraulically fracturing the Devonian Shale, while transporting sand as a proppant. The project scope includes considering candidate wells in up to five (5) states, Kentucky, Ohio, Tennessee, Virginia, and West Virginia. (2) To compare and rank the gas production responses from wells treated with liquid CO{sub 2} with other types of treatments (shooting, water based, nitrogen, etc. ). These demonstrations will involve two phases: Phase I -- up to fifteen (15) wells in up to five (5) target areas. (Aug. 93); Phase II -- up to nine (9) wells in up to three (3) target areas [seventeen (17) months].

  9. Multiple hydraulic fracture stimulation in a deep horizontal tight gas well

    SciTech Connect

    Abou-Sayed, I.S.; Schueler, S.; Ehrl, E. [and others

    1995-12-31

    This paper outlines the stimulation program used to successfully complete the 15,687 ft (4,783 m) TVD deep horizontal well Sochlingen Z-10 in the tight Rotliegendes sandstone onshore Germany. The program included the breakdown multiple rate infectivity test, use of proppant erosion stages to reduce near wellbore restrictions, and minifrac data analysis. Use of open annulus to analyze the stimulation treatment and modify the design is also covered. Considerations and experiments behind the design and execution of this horizontal well stimulation with hydraulic fractures perpendicular to the wellbore are presented and discussed. The well is now producing at a stable rate of 18 MMSCFD (20,000 m{sup 3}/hr).

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

    PubMed Central

    2014-01-01

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

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

    SciTech Connect

    Berryman, James G.

    2007-12-12

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

  12. Source Mechanisms of Low Frequency Seismicity in a Hydraulic Fracturing Context

    NASA Astrophysics Data System (ADS)

    Zecevic, M.; Daniel, G.; Hubans, F.; Gouedard, P.

    2014-12-01

    In recent years, long-period long-duration (LPLD) events have been observed during hydraulic fracturing of hydrocarbon reservoirs (Das & Zoback, 2013). LPLDs are low-amplitude signals lasting from tens of seconds to minutes. Their source mechanisms are not fully understood. However, as they are remarkably similar in character to tectonic tremors it has been suggested that they may also have comparable source models. Current models suggest that a tectonic tremor consists of numerous slow-slip earthquakes superposed on each other to form continuous waveforms (Shelley et al., 2007). These slow-slip earthquakes are thought to be a result of shear slip on faults close to failure with low confining pressure, most likely due to the presence of fluid with pore pressures close to lithostatic pressures (Peng & Gomberg, 2010). This study aims to further understand the source mechanism of LPLDs. A hydraulic fracturing dataset containing thousands of located microseismic earthquakes (MEQs) and numerous LPLDs is presented. The MEQs are located around the injection stages whereas the LPLDs are clustered in a limited region within the reservoir. This clustering suggests that LPLDs can only be generated where the conditions in the reservoir are favorable. These results correspond with the possibility that LPLDs are manifestations of slow-slip, with the source locations confined by variations in the mechanical properties of the reservoir. To test this hypothesis a further understanding of the mechanisms of LPLDs and the stress field in which they occur is needed. However, calculating focal mechanisms for LPLDs is difficult due to their emergent onset and lack of clear phases. Consequently, LPLDs must be put into context with the observed MEQs. We will present the spatial distribution of the focal mechanisms of the MEQs and analyze our findings with respect to the occurrence of the LPLD events.

  13. Vertical root fracture: preservation of the alveolar ridge using immediate implants.

    PubMed

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

    2014-01-01

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

  14. Dynamics of Model Hydraulic Fracturing Liquid Studied by Two-Dimensional Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Daley, Kim; Kubarych, Kevin J.

    2014-06-01

    The technique of two-dimensional infrared (2DIR) spectroscopy is used to expose the chemical dynamics of various concentrations of polymers and their monomers in heterogeneous mixtures. An environmentally relevant heterogeneous mixture, which inspires this study, is hydraulic fracturing liquid (HFL). Hydraulic fracking is a technique used to extract natural gas from shale deposits. HFL consists of mostly water, proppant (sand), an emulsifier (guar), and other chemicals specific to the drilling site. Utilizing a metal carbonyl as a probe, we observe the spectral dynamics of the polymer, guar, and its monomer, mannose, and compare the results to see how hydration dynamics change with varying concentration. Another polymer, Ficoll, and its monomer, sucrose, are also compared to see how polymer size affects hydration dynamics. The two results are as follows: (1) Guar experiences collective hydration at high concentrations, where as mannose experiences independent hydration; (2) no collective hydration is observed for Ficoll in the same concentration range as guar, possibly due to polymer shape and size. HFL experiences extremely high pressure during natural gas removal, so future studies will focus on how increased pressure affects the hydration dynamics of polymers and monomers.

  15. Fracture characterization of multilayered reservoirs

    SciTech Connect

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

    1986-01-01

    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.

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

    PubMed

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

    2014-11-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  18. Fracture orientation determination in Sandhills (McKnight) field, Crane County, Texas

    Microsoft Academic Search

    Olive

    1988-01-01

    A fracture identification log (FILMAP, Schlumberger) provided an orientation of vertical fracturing in the Sandhills (McKnight) field, Crane County, Texas. During workover operations to deepen an existing well bore to test a lower porosity interval, a 200-ft core was obtained that intersected a fracture plane in several sections of the core. Verification of this fracture having been hydraulically induced (or

  19. Expansion of decline curve parameters for tight gas sands with massive hydraulic fractures

    SciTech Connect

    Schaefer, T.

    1995-12-31

    With the advances in modern hydrocarbon technology and expansion of geologic settings for development, it is necessary to make changes to the conventional wisdoms that accompany production technology. This paper discusses some possible changes that necessitate implementation as observed both empirically and analytically. Specifically it discusses the time at which a decline curve can be implemented for production forecasting, the need for a dual decline model, and the severity of the decline variable that may be used for this model. It is the point of this paper to prove that for fight gas sands with massive hydraulic fractures that it is not only feasible to use decline variables that are greater than the traditional limit of harmonic or 1.0, but that the decline curve may also be implemented in the transient flow period of the well and decline both hyperbolically and exponentially. These ideas were not only proven through field study, but were additionally modeled with a fracture flow simulator. In order to prove these points this paper first introduces the Red Fork Formation and the development of an initial field model curve for this formation. After the initial model was developed, questions arose as to its feasibility. These questions were first addressed with a literature survey and further comparisons were made to test the models accuracy using pressure decline analysis and a fracture flow simulator. All of these methods were used to justify the implementation of a decline exponent as high as 2.1 for a hyperbolic curve during the early transient flow period, and regressing this hyperbolic into an exponential decline in the pseudo-steady state period.

  20. FAST TRACK PAPER: The creation of an asymmetric hydraulic fracture as a result of driving stress gradients

    NASA Astrophysics Data System (ADS)

    Fischer, T.; Hainzl, S.; Dahm, T.

    2009-10-01

    Hydraulic fracture stimulation is frequently performed in hydrocarbon reservoirs and geothermal systems to increase the permeability of the rock formation. These hydraulic fractures are often mapped by hypocentres of induced microearthquakes. In some cases microseismicity exhibits asymmetry relative to the injection well, which can be interpreted by unequal conditions for fracture growth at opposite sides of the well or by observation effects. Here we investigate the role of the lateral change of the minimum compressive stress. We use a simple model to describe the relation among the lateral stress gradient, the mean viscous pressure gradients in the fracture wings, the fracture geometry, and the net pressure in the fracture. Our model predicts a faster fracture growth in the direction of decreasing stress and a limited growth in the opposite direction. We derive a simple relationship to estimate the lateral stress gradient from the injection pressure and the shape of the seismic hypocentre cloud. The model is tested by microseismic data obtained during stimulation of a Canyon Sands gas field in West Texas. Using a maximum likelihood method we fit the parameters of the asymmetric fracture model to the space-time pattern of hypocentres. The estimated stress gradients per metre are in the range from 0.008 to 0.010 times the bottom-hole injection overpressure (8-10 kPam-1 assuming the net pressure of 1 MPa). Such large horizontal gradients in the order of the hydrostatic gradient could be caused by the inhomogeneous extraction of gas resulting in a lateral change of the effective normal stress acting normal to the fracture wall.