Sample records for vertical hydraulic fracture

  1. On the Design of Vertical Hydraulic Fractures

    Microsoft Academic Search

    Abbas Daneshy

    1973-01-01

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

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

    E-print Network

    Briggs, Kathryn

    2014-05-05

    Hydraulic fracturing is the primary stimulation method within low permeability reservoirs, in particular shale reservoirs. Hydraulic fracturing provides a means for making shale reservoirs commercially viable by inducing and propping fracture...

  3. 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.

  4. Hydraulic fracturing-1

    SciTech Connect

    Not Available

    1990-01-01

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

  5. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    SciTech Connect

    Uhri, D.C.

    1988-01-12

    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 slugs of a thin-fluid spacer and a temporary blocking agent having a proppant therein into the fracture; (d) maintaining the hydraulic pressure on the formation while pumping alternate slugs of the thin-fluid spacer and the blocking agent into the second hydraulic fracture; (e) maintaining the hydraulic pressure on the formation while pumping alternate slugs of the thin-fluid spacer and the blocking agent into the last formed hydraulic fracture; (f) maintaining the hydraulic pressure on the formation while pumping alternate slugs of the thin-fluid spacer and the blocking agent into the last formed hydraulic fracture to cause the last formed hydraulic fracture to propagate away from the previously formed hydraulic fractures in a curved trajectory which eventually becomes substantially perpendicular to the original least principal in-situ stress due to the interaction of the original in-situ stresses and stresses from previously formed hydraulic fractures with the last formed hydraulic fracture; and (g) repeating steps (e) and (f) until a desired number of curved sequential hydraulic fractures are created as extensions to the multiple vertical radial fractures obtained in step (a).

  8. 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

  9. Simultaneous hydraulic fracturing

    SciTech Connect

    Uhri, D.C.

    1989-05-16

    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 in both wells which pressure is sufficient to fracture the formation thereby causing a fracture to be propagated from each well in a curved manner sufficient to intersect at least one natural hydrocarbonaceous fluid-bearing fracture.

  10. 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.

  11. 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.

  12. 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....

  13. Hydraulic fracturing of a shallow subsurface formation

    SciTech Connect

    Uhri, D.C.

    1987-12-22

    A method for propagating a vertical hydraulic fracture in an earth formation surrounding a borehole where the original in-situ stresses favor a horizontal fracture is described comprising the steps of: (a) firstly supplying fracturing fluid to the formation at a first depth within the borehole to propagate a horizontal fracture favored by the original in-situ stresses of the formation, and (b) secondly supplying fracturing fluid to the formation at a second depth within the borehole, while maintaining pressure in the horizontal fracture, to propagate a vertical fracture as favored by the in-situ stresses as altered by the propagating of the horizontal fracture.

  14. 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.

  15. Computer simulation of hydraulic fractures

    Microsoft Academic Search

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

    2007-01-01

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

  16. Maximizing fracture extension in massive hydraulic fracturing

    SciTech Connect

    Smith, M.B.

    1984-03-06

    During fracture treatment of a subterranean formation, multiple hydraulic fracturing cycles are performed wherein the bottomhole treating pressure of a wellbore is controlled to not exceed a maximum bottomhole treating pressure for the formation, thereby attaining maximum principle fracture extension and limiting initiation of secondary fractures transverse to the principle fracture extension.

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

    NASA Astrophysics Data System (ADS)

    Hubble, David Wallace

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

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

    Microsoft Academic Search

    Lawrence Teufel; James Clark

    1984-01-01

    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

  19. Sequential hydraulic fracturing of a subsurface formation

    SciTech Connect

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

    1989-09-26

    This patent describes a method for propagating a vertical hydraulic fracture in an earth formation surrounding a borehole wherein the original in-situ stresses favor a horizontal fracture. It comprises: pumping a first fracturing fluid into the formation at a first depth within the borehole so that a first fracturing pressure is applied to the formation by the first fracturing fluid to propagate a horizontal fracture as favored by the original in-situ stresses of the formation. The propagation of the horizontal fracture altering the original in-situ stresses in the formation; injecting a propping material into the horizontal fracture while maintaining the first fracturing pressure in the horizontal fracture in sufficient amount to prevent relaxation of the altered in-situ stresses in the formation after the pumping of the first fracturing fluid is terminated and the first fracturing pressure is removed; terminating the pumping of the first fracturing fluid into the horizontal fracture to remove the first fracturing pressure from the formation, pumping a second fracturing into the formation at a second depth within the borehole within the field of the altered in-situ stresses,; and terminating the pumping of the second fracturing fluid to the vertical fracture to remove the second fracturing pressure from the formation.

  20. Study of Nordgren's Equation of Hydraulic Fracturing

    Microsoft Academic Search

    L. Kemp

    1990-01-01

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

  1. Creation of multi-azimuth permeable hydraulic fractures

    SciTech Connect

    Uhri, D.C.; Jennings, A.R. Jr

    1989-05-30

    This patent describes a process for creating multi-azimuth fractures via hydraulic fracturing in a subterranean formation containing at least one wellbore comprising: (a) applying a hydraulic fracturing pressure into the formation through a liquid in the wellbore which pressure is sufficient to fracture the formation thereby forming at least one vertical fracture; (b) releasing the pressure and directing into the wellbore a solidifiable gel material sufficient to form a temporary plug within a desired time and distance within the formation; (c) allowing the solidifiable gel material to form a plug within the vertically created fracture; and (d) applying thereafter into the formation through a liquid in the wellbore a pressure sufficient to propagate at least one dendritic fracture from the existing vertical fracture because of the temporary plug in the fracture which dendritic fracture intersects a natural fracture system.

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

    E-print Network

    Xue, Wenxu

    2011-02-22

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

  3. Numerical simulation of hydraulic fracturing

    E-print Network

    Warner, Joseph Barnes

    1987-01-01

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

  4. 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...

  5. Poroelasticity in hydraulic fracturing simulators

    SciTech Connect

    Vandamme, L. (Noranda Technology Centre, Pte. Claire, Quebec (CA)); Roegiers, J.C. (School of Petroleum and Geological Engineering, Univ. of Oklahoma, OK (US))

    1990-09-01

    This paper describes a 2D hydraulic fracturing simulator that relies on Biot's theory of poroelasticity. The simulator is based on a poroelastic extension of the displacement-discontinuity (DD) method: it uses time and space distributions of impulse-point DD's and impulse-point sources. Because both solutions satisfy Biot's equations, the model fully accounts for the coupling between fluid diffusion and rock deformation. Thus, this model yields a rigorous determination of the influences of fluid leakoff on fracture width and of opening distribution on reservoir pore pressures. Some preliminary results relevant to hydraulic fracturing are presented.

  6. 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.

  7. Method for directional hydraulic fracturing

    DOEpatents

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

    1994-01-01

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

  8. Regulation of Hydraulic Fracturing in California

    E-print Network

    Kammen, Daniel M.

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

  9. Hydraulic Fracture: multiscale processes and moving

    E-print Network

    Peirce, Anthony

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

  10. 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

  11. Hydraulic Fracture: multiscale processes and moving

    E-print Network

    Peirce, Anthony

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

  12. Hydraulic conductivity of rock fractures

    SciTech Connect

    Zimmerman, R.W.; Bodvarsson, G.S.

    1994-10-01

    Yucca Mountain, Nevada contains numerous geological units that are highly fractured. A clear understanding of the hydraulic conductivity of fractures has been identified as an important scientific problem that must be addressed during the site characterization process. The problem of the flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of rigorous 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 kinetic conditions that are necessary in order for the Navier-Stokes equations to be replaced by the more tractable lubrication or Hele-Shaw equations are studied and quantified. Various analytical and numerical results are reviewed pertaining to the problem of relating the effective hydraulic aperture to the statistics of the aperture distribution. These studies all lead to the conclusion that the effective hydraulic aperture is always less than the mean aperture, by a factor that depends on the ratio of the mean value of the aperture to its standard deviation. The tortuosity effect caused by regions where the rock walls are in contact with each other is studied using the Hele-Shaw equations, leading to a simple correction factor that depends on the area fraction occupied by the contact regions. Finally, the predicted hydraulic apertures are compared to measured values for eight data sets from the literature for which aperture and conductivity data were available on the same fracture. It is found that reasonably accurate predictions of hydraulic conductivity can be made based solely on the first two moments of the aperture distribution function, and the proportion of contact area. 68 refs.

  13. Monitoring hydraulic fracture growth: Laboratory experiments

    SciTech Connect

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

    2000-04-01

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

  14. Beam model for hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Tzschichholz, F.; Herrmann, H. J.; Roman, H. E.; Pfuff, M.

    1994-03-01

    We investigate numerically the shape of cracks obtained in hydraulic fracturing at constant pressure using a square-lattice beam model with disorder. We consider the case in which only beams under tension can break, and discuss the conditions under which the resulting cracks may develop fractal patterns. We also determine the opening volume of the crack and the elastic stress field in the bulk, quantities that are accessible experimentally.

  15. Identifying Best Practices in Hydraulic Fracturing Using

    E-print Network

    Mohaghegh, Shahab

    Identifying Best Practices in Hydraulic Fracturing Using Virtual Intelligence Techniques SPE 72385 Results & Discussion Conclusion #12;SPE 72385 OBJECTIVE To identify Best Practices in Hydraulic Fracturing, are fractured upon completion to provide economic amounts of gas. #12;SPE 72385 BACKGROUND A dataset

  16. 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. We have conducted laboratory hydraulic fracture experiments and elastic finite element studies which show that at least two 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.

  17. Enhanced hydraulic fracturing of a shallow subsurface formation

    SciTech Connect

    Hazlett, R.D.; Uhri, D.C.

    1989-07-18

    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 agent are contained in the slug in an amount sufficient to generate fracturing pressure after propagating a horizontal hydraulic fracture; supplying additional fracturing fluid at the first depth thereby fracturing the formation and propagating a horizontal fracture which places the slug a desired distance from the well; causing the chemical blowing agent to decompose and liberate gas sufficient to form a foam thereby extending the propagated horizontal fracture further into the formation; and supplying fracturing fluid to the formation at a second depth within the borehole while maintaining pressure in the horizontal fracture. Thereby propagating a vertical fracture to an extended distance as favored by the in-situ stresses as altered by the propagating of the horizontal fracture.

  18. 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 ...

  19. 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

  20. Hydraulic fracture during epithelial stretching

    NASA Astrophysics Data System (ADS)

    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.

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

    E-print Network

    Ahmed, Ibraheem 1987-

    2012-11-30

    Successful development of shale gas reservoirs is highly dependent on hydraulic fracture treatments. Many questions remain in regards to the geometry of the created fractures. Production data analysis from some shale gas wells quantifies a much...

  2. Hydraulic Fracturing: Identifying and Managing the Risks

    Microsoft Academic Search

    Earl L. Hagström; Julia M. Adams

    2012-01-01

    Massive domestic natural gas reserves previously uneconomical to develop are now, through hydraulic fracturing, feasible to produce. The process, which involves the injection of millions of gallons of water and chemical additives under high pressure into the subsurface, is not without risk. Over three dozen lawsuits have been filed alleging that hydraulic fracturing has caused damages to drinking water supplies,

  3. Modeling of Interaction of Hydraulic Fractures in Complex Fracture Networks

    NASA Astrophysics Data System (ADS)

    Kresse, O. 2; Wu, R.; Weng, X.; Gu, H.; Cohen, C.

    2011-12-01

    A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. Multiple fracture branches can propagate at the same time and intersect/cross each other. Each open fracture exerts additional stresses on the surrounding rock and adjacent fractures, which is often referred to as "stress shadow" effect. The stress shadow can cause significant restriction of fracture width, leading to greater risk of proppant screenout. It can also alter the fracture propagation path and drastically affect fracture network patterns. It is hence critical to properly model the fracture interaction in a complex fracture model. A method for computing the stress shadow in a complex hydraulic fracture network is presented. The method is based on an enhanced 2D Displacement Discontinuity Method (DDM) with correction for finite fracture height. The computed stress field is compared to 3D numerical simulation in a few simple examples and shows the method provides a good approximation for the 3D fracture problem. This stress shadow calculation is incorporated in the UFM. The results for simple cases of two fractures are presented that show the fractures can either attract or expel each other depending on their initial relative positions, and compares favorably with an independent 2D non-planar hydraulic fracture model. Additional examples of both planar and complex fractures propagating from multiple perforation clusters are presented, showing that fracture interaction controls the fracture dimension and propagation pattern. In a formation with no or small stress anisotropy, fracture interaction can lead to dramatic divergence of the fractures as they tend to repel each other. However, when stress anisotropy is large, the fracture propagation direction is dominated by the stress field and fracture turning due to fracture interaction is limited. However, stress shadowing still has a strong effect on fracture width, which affects the injection rate distribution into multiple perforation clusters, and hence overall fracture network geometry and proppant placement.

  4. Dynamics of Hydraulic-Fracturing Controlled Microseismicity

    Microsoft Academic Search

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

    2006-01-01

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

  5. The crack tip region in hydraulic fracturing

    Microsoft Academic Search

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

    1994-01-01

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

  6. DEMONSTRATION BULLETIN: HYDRAULIC FRACTURING OF CONTAMINATED SOIL

    EPA Science Inventory

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

  7. Hydraulic fracturing utilizing a refractory proppant

    SciTech Connect

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

    1990-01-01

    This patent describes a method for hydraulically fracturing a formation where a fused refractory proppant is used. It comprises: placing into a fracturing fluid a fused refractory proppant consisting essentially of silicon carbide or silicon nitride having a mohs hardness of about 9 and in an amount sufficient to prop a created fracture where the proppant is substantially crush and acid resistant; injecting into the formation the fracturing fluid with the proppant therein under a pressure sufficient to fracture the formation; and fracturing the formation and thereafter causing the pressure to be released thereby propping at least one fracture which proppant provides for increased heat transfer into the formation.

  8. Hydraulic Fracturing and the Environment

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. 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.

  10. 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.

  11. 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 ...

  12. Interaction between Injection Points during Hydraulic Fracturing

    E-print Network

    Hals, Kjetil M D

    2012-01-01

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

  13. Initiation of Hydraulic Fractures in Natural Sandstones

    Microsoft Academic Search

    T. P. Y. Lhomme

    2005-01-01

    Hydraulic fracturing is a stimulation technique commonly used for the enhancement of hydrocarbon reservoir recovery. Controlling the initiation of a hydraulic fracture from the open-hole section of a well without zone isolation requires an in-depth understanding of the factors which have a decisive effect on the onset and early growth of a fluid-driven crack. The objective of this research is

  14. 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.

  15. Hydraulic Fracturing Mineback Experiment in Complex Media

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  16. Hydraulic fracturing in tight fissured media

    SciTech Connect

    Warpinski, N.R. (Sandia National Labs., Albuquerque, NM (USA))

    1989-01-01

    There are tremendous resources of natural gas in tight fissured rocks, but these formations require special care for hydraulic fracturing to be successful. Serious problems include leakoff, damage and complex fracturing. These problems are discussed. 51 refs., 8 figs., 1 tab.

  17. The influence of plasticity in hydraulic fracturing

    Microsoft Academic Search

    Panos Papanastasiou

    1997-01-01

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

  18. 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.

  19. Universal asymptotic umbrella for hydraulic fracture modeling

    E-print Network

    Linkov, Aleksandr M

    2014-01-01

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

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

    Microsoft Academic Search

    Larry McKay; J. Fredericia

    1995-01-01

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

  1. 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

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

    E-print Network

    Paris-Sud XI, Université de

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

  4. Effectiveness of microseismic monitoring for optimizing hydraulic fracturing in California

    E-print Network

    Alampi, Ann M

    2014-01-01

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

  5. GEOL440, GEOL524 Sedimentary Geology: Hydraulic Fracturing Seminar

    E-print Network

    Nickrent, Daniel L.

    GEOL440, GEOL524 Sedimentary Geology: Hydraulic Fracturing Seminar M,W,F 1PM-1:50AM Parkinson 110-directed seminar class in which we will investigate the issues surrounding hydraulic fracturing (fracking

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

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

    E-print Network

    Yener, Aylin

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

  12. Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers

    E-print Network

    Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers by Tom Myers Abstract Hydraulic fracturing of deep shale beds to develop natural gas has caused concern regarding the potential allow advective transport to aquifers in less than 10 years. The rapid expansion of hydraulic fracturing

  13. 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.

  14. 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...

  15. Gas condensate damage in hydraulically fractured wells

    E-print Network

    Reza, Rostami Ravari

    2004-11-15

    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...

  16. Hydraulic fracture model comparison study: Complete results

    SciTech Connect

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

    1993-02-01

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

  17. An analytical model for hydraulic fracturing in shallow bedrock formations.

    PubMed

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

    2011-01-01

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

  18. 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

  19. 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

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

    E-print Network

    Xiang, Jing

    2012-02-14

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

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

    Microsoft Academic Search

    F. Cappa; Y. Guglielmi; P. Fénart; V. Merrien-Soukatchoff; A. Thoraval

    2005-01-01

    Hydromechanical coupled processes in a shallow fractured carbonate reservoir rock were investigated through field experiments coupled with analytical and numerical analyses. The experiments consist of hydraulic loading\\/unloading of a water reservoir in which fluid flow occurs mainly inside a heterogeneous fracture network made up of vertical faults and bedding planes. Hydromechanical response of the reservoir was measured using six pressure–normal

  2. Uncertainty Analysis of Simulated Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  3. 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.

  4. Fracturing Demonstration using a Hydraulic Press

    NSDL National Science Digital Library

    James B. Harris

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

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

    SciTech Connect

    Mike L. Laue

    1997-05-30

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

  6. Stimulation of earth formations surrounding a deviated wellbore by sequential hydraulic fracturing

    SciTech Connect

    Uhri, D.C.

    1987-08-18

    A method is described for the stimulation of oil and gas production from a naturally fractured earth formation surrounding a deviated wellbore by sequential hydraulic fracturing, comprising the steps of: (a) firstly supplying fracturing fluid to the formation at a first depth within the deviated wellbore to propagate a first vertical fracture as favored by the original in-situ stresses of the formation in a direction that is perpendicular to the least principal in-situ stress, the formation of the first vertical fracture altering the local in-situ stresses, and (b) secondly supplying fracturing fluid to the formation at a second depth within the wellbore, while maintaining pressure in the first vertical fracture, to propagate a second vertical fracture through the formation in a direction parallel to the least principal in-situ stress as favored by the altering of the local in-situ stresses by the first vertical fracture, such that the second vertical fracture intersects the naturally occurring fractures in the formation which are perpendicular to the direction of the least principal in-situ stress so as to link the naturally occurring fractures to the wellbore and thereby stimulate the production of oil or gas from the formation.

  7. 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.

  8. Hydraulic Fracturing Return Waters and Legacy Landscapes

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Hydraulic fracturing of gas-bearing shales to enhance recovery is growing increasingly common globally. However, disposal of return water remains a challenge, particularly in humid environments where evapoconcentration potential is limited. Further, return water typical of recent activity in the Marcellus Shale in the eastern United States is substantially saltier relative to other shales where hydraulic fracturing has been employed. This presentation explores scenarios of both traditional return water disposal and accidental releases of return water to fluvial systems using simple exchange modeling, with particular attention to conditions in landscapes typical of Marcellus country. That is, these simulations will incorporate a historic context, acknowledging decades of coal extraction from surface and sub-surface mines and energy production via combustion of said coal. The interactions between “naturally attenuated” historic contamination and rapidly changing water chemistry are critical to accurate risk assessment in this uncertain environment.

  9. Field characterization of vertical bromide transport in a fractured glacial till

    Microsoft Academic Search

    William G. Harrar; Lawrence C. Murdoch; Bertel Nilsson; Knud Erik S. Klint

    2007-01-01

    A study of the fracture distribution, hydraulic properties, groundwater levels and the transport of bromide was conducted\\u000a to characterize vertical transport in the oxidized and reduced zones of a fractured glacial till. Detailed vertical profiles\\u000a of groundwater levels and solute concentrations were obtained over a 4.5-year period. Vertical migration occurred at several\\u000a time scales, as a low concentration front was

  10. 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

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    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 asymmetric fracture with a twice longer eastern wing containing 80% of the located events was observed. Owing to the planarity of the microseismic cloud, it was possible to reduce the location problem to two dimensions and to use only S waves for event localization. Thus, because of the larger amplitudes of S waves, a fourfold increase in the number of located events was achieved. We find that the length of the hydraulic fracture increased, for different depth intervals, both linear and nonlinear in time. We use hydraulic fracture models to explain the spreading of the microseismic front, whose nonlinear time dependence could indicate either a diffusive fluid flow or a two-dimensional growth of the hydraulic fracture. By the maximum-likelihood fitting of the observed fracture growth and by inverting for its parameters, we find that the fracture was 7-10 mm wide and that nearly the whole injected volume was used for creating the new fracture, that is a negligible diffusive infiltration of the injected fluid into the reservoir rock occurred.

  13. 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

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

    E-print Network

    Zhang, Junjing

    2014-07-10

    Multi-stage hydraulic fracturing is the key to the success of many shale gas and shale oil reservoirs. The main objectives of hydraulic fracturing in shale are to create artificial fracture networks that are conductive for oil and gas flow...

  15. HYDRAULIC FRACTURE MODEL SENSITIVITY ANALYSES OF MASSIVELY STACKED LENTICULAR RESERVOIRS

    E-print Network

    HYDRAULIC FRACTURE MODEL SENSITIVITY ANALYSES OF MASSIVELY STACKED LENTICULAR RESERVOIRS that there was an abundant system of micro-scale natural fractures and a less frequent system of macro- scale fractures. In common with most tight gas reservoirs, hydraulic stimulation is required to interconnect the dual

  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. Hydraulic Fractures: multiscale phenomena, asymptotic and numerical solutions

    E-print Network

    Peirce, Anthony

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

  18. 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

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

    SciTech Connect

    David S. Schechter

    2005-04-27

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

  20. Vertical root fractures and their management.

    PubMed

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

    2014-03-01

    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

  1. 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

  2. Hydraulic Fracture Monitoring: A Jonah Field Case Study

    E-print Network

    Seher, T.

    2011-01-01

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

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

    EPA Science Inventory

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

  4. 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

  5. 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.

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

    PubMed

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

    2013-01-01

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

  7. 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...

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

    E-print Network

    McKenzie, Jeffrey M.

    Hydraulic fracturing in faulted sedimentary basins: Numerical simulation of potential contamination 2013. [1] Hydraulic fracturing, used to economically produce natural gas from shale formations, has issues, which is the potential for slow contamination of shallow groundwater due to hydraulic fracturing

  9. 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

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

  10. 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

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

  11. 75 FR 35023 - Informational Public Meetings for Hydraulic Fracturing Research Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ...Informational Public Meetings for Hydraulic Fracturing Research Study AGENCY: Environmental...the relationship between hydraulic fracturing and drinking water. The...the meetings. DATES: The Hydraulic Fracturing Study informational...

  12. 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

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

  13. [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

  14. Hydraulic characterization of the fracture framework in carbonate rock underlying CWML Site, Smithville, Ontario

    SciTech Connect

    Lapcevic, P.; Novakowski, K.; Bickerton, G.; Voralek, J. [National Water Research Inst., Burlington, Ontario (Canada)

    1997-12-31

    The successful use of engineered systems to contain and/or remediate the contaminated groundwater in the bedrock underlying the CWML site at Smithville, ON is largely dependent on an understanding of the complex groundwater flow system. The Lockport Dolostone, which underlies most of the Niagara peninsula, is a shallow flat-lying porous carbonate rock having extensive horizontal bedding plane fractures. Vertical fractures which intersect the bedding planes form a three dimensional fracture framework. Detailed field investigations are currently underway to characterize groundwater flow within this fracture framework. To conduct the investigation fifteen boreholes were drilled through the entire thickness of the Lockport Formation. The distribution of both vertical and bedding plane fractures was delineated from core analysis. Constant-head hydraulic tests using 2 meter and 0.5 meter packer test intervals were used to determine both the bulk transmissivity of the unfractured rock mass and that for individual fractures. The results show that while most breaks noted in the core are bedding-plane fractures or broken-core zones, vertical fractures are also prevalent particularly in the Eramosa Formation. Fracture strikes show a dominant joint sets consistent with trends observed regionally. The vertical distribution of transmissivity in the Lockport Dolostone ranges over eight orders of magnitude at the site. Preliminary geostatistical analysis suggests that there may be at least three separate distributions of structure present in the transmissivity data: (1) distribution of the T of fractures, (2) distribution of the T of the matrix, and (3) position of the fractures.

  15. 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.

  16. FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS

    EPA Science Inventory

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

  17. Observations of long period earthquakes accompanying hydraulic fracturing

    Microsoft Academic Search

    Dorthe Bame; Michael Fehler

    1986-01-01

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

  18. On equivalence of thinning fluids used for hydraulic fracturing

    E-print Network

    Linkov, Alexander

    2012-01-01

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

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

    E-print Network

    Patzek, Tadeusz W.

    ANALYSIS OF GAS PRODUCTION FROM HYDRAULICALLY FRACTURED WELLS IN THE HAYNESVILLE SHALE USING. INTRODUCTION Before the advent of hydraulic fracturing technology and hor- izontal drilling, the Haynesville

  20. 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.

  1. 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.

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

    E-print Network

    Gist, Stephen Rhett

    1984-01-01

    in Hydraulically Fractured Reservoirs. (May 1984) Stephen Rhett Gist, B. Sc. , Texas A dr. M University Chairman of Advisory Committee: W. J. Lee Low permeability gas reservoirs need to be hydraulically fractured to be economically productive. Knowledge... fractured, low permeability gas wells. The technique combines a modified Milheim and Cichowicz square root of time analysis with permeability correction factors to simultaneously calculate formation permeability, fracture length and fracture conductivity...

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

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Jeffrey, Robert G.

    2012-12-01

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

  4. DETERMINATION OF PRINCIPAL STRESSES AND CONFINEMENT OF HYDRAULIC FRACTURES IN COTTON VALLEY

    Microsoft Academic Search

    Michael Rosepiler

    1979-01-01

    In order to delineate formations that will inhibit the vertical growth of hydraulic fractures, the principal stress within the formations must be known. The principal stresses can be calculated from density and acoustic logs. Overburden pressure is obtained by integrating density logs. The lithostatic gradient in Cotton Valley is approximately 1.07 psi\\/ft. Digitized acoustic wavetrains are processes to calculate Poisson's

  5. 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.

  6. Public health and high volume hydraulic fracturing.

    PubMed

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

    2013-01-01

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

  7. Hydraulic-fracturing controlled dynamics of microseismic clouds

    Microsoft Academic Search

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

    2006-01-01

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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Hydraulic fracturing: paving the way for a sustainable future?

    PubMed

    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

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

    SciTech Connect

    Schmidt, R.A.

    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 a microcrack model is also needed in order to understand rock fracture testing on the laboratory scale and to help establish guidelines for fracture toughness testing. Initial calculations and results with this model reveal several explanations for anomalous behavior in hydraulic fracturing and in fracture toughness testing. 3 figures.

  14. Electrokinetic coupling in hydraulic fracture propagation

    NASA Astrophysics Data System (ADS)

    Cuevas, Nestor Herman

    2009-12-01

    Electrokinetic coupling is the most popular mechanism proposed to explain observed electromagnetic signals associated with the hydraulic fracturing of rocks. Measurements in both controlled laboratory and in situ conditions show clear evidence of the phenomenon. However there have been no reports on the description of the source mechanism, its relationship to a propagating crack, nor the electromagnetic field distribution due to such a source advancing through an electrically conductive medium. In this work it is shown that a surface electric current density arising on the walls of a fluid driven propagating crack can explain the measurements of electric streaming potential recorded during hydraulic fracturing experiments. The properties of the streaming current source are studied at the microscopic scale in light of the electrokinetic coupling expected at the outermost grains of the crack's surface. Expressions are derived for the average macroscopic transport equations describing the coupled fluid, and electrical current flow, at the interface between a fluid continuum and a homogeneous porous medium, where a Darcy flow regime (porous medium) competes with a rather Poiseuille type (fracture channels). The properties of the electrokinetic boundary sources are analyzed in light of the average electrical current density arising on the interface, as the fluid electrolyte flows in both the porous media and the adjacent fluid continuum. It is found that two coupling coefficients are required to describe the streaming current density. Indeed the flow is driven by both, a tangential pressure gradient, as well as by forward momentum transfer across the permeable boundary. The coupling coefficients are obtained from the spatial average of the tangential stress exerted on the pore surfaces, and they are found to be position dependent, as the tangential stress transitions from that on the porous conduits, to that on the surface of the outer most grains. Furthermore each coefficient gives rise to both a volumetric current density, due to the flow along the pore conduits, as well as a surface current density, due to the flow along the outer most surface. The latter contribution is found to dominate, as the tangential stress scales with the macroscopic characteristic length of the system. From a macroscopic stand point a source space-time function is established for the average current density prescribed by the pressure profile expected at the walls of a crack, which propagates under mobile equilibrium, in the context of linear elasticity theory. Expressions for the electromagnetic fields due to such a source are derived for a crack propagating with a constant velocity, in a homogeneous isotropic conducting medium. It is found that the spatial and temporal behavior of the fields reasonably agree with measurements performed under controlled laboratory experiments. In situ measurements are only studied qualitatively. Nevertheless, despite the obvious fact that a homogeneous whole-space medium does not appropriately describe a realistic earth model, the magnitude of the fields and the temporal behavior of the signals can be well reproduced using typical parameters of a hydraulic fracturing procedure. Electrokinetic coupling has also been proposed in the context of earthquake precursory signals, due to dilatant crack growth at depth. Several ideas have been discussed in the literature in order to justify experimental measurements of electromagnetic field which presumably appear before the onset of an earthquake. The source mechanism described in the present report, occurring at depth ranges of earthquake slip zones, yields electromagnetic signal levels which are 3 orders of magnitude smaller than the noise floor of currently available commercial instrumentation. This suggests that observing this type of phenomenon as an earthquake precursor would then be very challenging.

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

    E-print Network

    Marpaung, Fivman

    2008-10-10

    INVESTIGATION OF THE EFFECT OF GEL RESIDUE ON HYDRAULIC FRACTURE CONDUCTIVITY USING DYNAMIC FRACTURE CONDUCTIVITY TEST A Thesis by FIVMAN MARPAUNG 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 2007 Major Subject: Petroleum Engineering INVESTIGATION OF THE EFFECT OF GEL RESIDUE ON HYDRAULIC FRACTURE CONDUCTIVITY USING DYNAMIC FRACTURE CONDUCTIVITY TEST A...

  16. 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

    EFFECTS OF FRACTURING FLUID RECOVERY UPON WELL PERFORMANCE AND ULTIMATE RECOVERY OF HYDRAULICALLY FRACTURED GAS WELLS A Thesis IAN MARIE BERTHELOT Submitted to the Office of Graduate Studies of Texas AdtM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1990 Major Subject: Petroleum Engineering EFFECTS OF FRACTURING FLUID RECOVERY UPON WELL PERFORMANCE AND ULTIMATE RECOVERY OF HYDRAULICALLY FRACTURED GAS WELLS by JAN MARIE BERTIIELOT Appmved...

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

    SciTech Connect

    Mike L. Laue

    2001-09-28

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

  18. Microseismicity Induced by Hydraulic Fracturing in Oil and Gas Wells

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  19. Vertical root fracture: prevalence, etiology, and diagnosis.

    PubMed

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

    2013-07-01

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

  20. Linear Elastic and Cohesive Fracture Analysis to Model Hydraulic Fracture in Brittle and Ductile Rocks

    NASA Astrophysics Data System (ADS)

    Yao, Yao

    2012-05-01

    Hydraulic fracturing technology is being widely used within the oil and gas industry for both waste injection and unconventional gas production wells. It is essential to predict the behavior of hydraulic fractures accurately based on understanding the fundamental mechanism(s). The prevailing approach for hydraulic fracture modeling continues to rely on computational methods based on Linear Elastic Fracture Mechanics (LEFM). Generally, these methods give reasonable predictions for hard rock hydraulic fracture processes, but still have inherent limitations, especially when fluid injection is performed in soft rock/sand or other non-conventional formations. These methods typically give very conservative predictions on fracture geometry and inaccurate estimation of required fracture pressure. One of the reasons the LEFM-based methods fail to give accurate predictions for these materials is that the fracture process zone ahead of the crack tip and softening effect should not be neglected in ductile rock fracture analysis. A 3D pore pressure cohesive zone model has been developed and applied to predict hydraulic fracturing under fluid injection. The cohesive zone method is a numerical tool developed to model crack initiation and growth in quasi-brittle materials considering the material softening effect. The pore pressure cohesive zone model has been applied to investigate the hydraulic fracture with different rock properties. The hydraulic fracture predictions of a three-layer water injection case have been compared using the pore pressure cohesive zone model with revised parameters, LEFM-based pseudo 3D model, a Perkins-Kern-Nordgren (PKN) model, and an analytical solution. Based on the size of the fracture process zone and its effect on crack extension in ductile rock, the fundamental mechanical difference of LEFM and cohesive fracture mechanics-based methods is discussed. An effective fracture toughness method has been proposed to consider the fracture process zone effect on the ductile rock fracture.

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Šílený, Jan; Hill, David P.; Eisner, Leo; Cornet, Francois H.

    2009-08-01

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

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

    USGS Publications Warehouse

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

    2002-01-01

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

  4. EPA Study of Hydraulic Fracturing and Drinking Water Resources

    EPA Science Inventory

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

  5. 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 ...

  6. Shear and tension hydraulic fractures in low permeability rocks

    USGS Publications Warehouse

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

    1977-01-01

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

  7. 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.

  8. 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... for the degree of MASTER OF SCIENCE August, 1963 Major Subject: Petroleum Engineering AN INVESTIGATION OF PRODUCTIVITY INCREASES FROM HYDRAULIC FRACTURING TREATMENTS A Thesis Robert Joe Boriskie Approved as to style and content by: Chairman of Committee...

  9. Low permeability gas reservoir production using large hydraulic fractures

    E-print Network

    Holditch, Stephen A

    1970-01-01

    LOVT PERMEABILITY GAS RESERVOIR PRODUCTION USING LARGE HYDRAULIC FRACTURES A Thesis by STEPHEN ALLEN HOLDITCH Approved as to style and content by: ( airman of Committee) (Head of Department) (Me er) (Member) (Membe r) (Member) (Member...) August 1970 111 ABSTRACT Low Permeability Gas Reservoir Production Using Large Hydraulic Fractures. (August 1970) Stephen Allen Holditch, B. S. , Texas ARM University Directed by: Dr, R. A. Morse There has been relatively little work published...

  10. Stochastic Modeling of a Fracture Network in a Hydraulically Fractured Shale-Gas Reservoir

    E-print Network

    Mhiri, Adnene

    2014-08-10

    of the hydraulic fracture patterns created during the well stimulation process. This work introduces a novel approach to model the hydraulic fractures in a shale reservoir using a stochastic method called random-walk. We see this approach as a beginning step...

  11. Hydraulic Fracture Along Glacier Beds by Turbulent Flow of Meltwater

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The problem of hydraulic fracture has been studied extensively, with focus ranging from enhanced hydrocarbon flow to boreholes, to water-driven glacial cracking, to magma eruption through Earth's crust. Although some of this work has addressed fast-flowing fracture, the work applied to glaciers has, so far, focused either on static or relatively long timescale conditions. However, glaciological observations suggest that the fluid-induced fracture process may occur quickly, possibly driven by turbulently flowing water during crack growth. Here, we take the approximation of a fully turbulent flow into an elastic ice medium with small fracture toughness to derive an approximate expression for the crack-tip speed. We accomplish this by first showing that a Manning channel model for wall resistance to turbulent flow leads to the same mathematical structure as for resistance to laminar flow of a power-law viscous fluid. We then make use of the asymptotic crack solution for that case by Desroches et al. [Proc. R. Soc. Lond. A, 1994], and finally estimate the pressure scale appropriate for a finite crack. Comparison of this estimated solution with an exact self-similar solution of Adachi and Detournay [Int. J. Numer. Anal. Meth. Geomech., 2002] validates the approximation. To apply this model, we use parameter values thought appropriate for a basal crack driven by the rapid drainage of a surface meltwater lake near the margin of the Greenland Ice Sheet (Das et al. [Science, 2008]). Thus, we take a maximum excess crack inlet pressure of 0.9 MPa, corresponding to neglect of any hydraulic head loss in flow from the glacier surface to crack entry at the bed, a horizontal basal crack length of 1 km, and a wall roughness scale for flow resistance of 10 mm, and hence estimate a crack-tip speed of about 8 m/s. Loss of ten percent of the surface head on descent to the bed would reduce that speed by slightly more than ten percent. Making various plate theory and linear elastic fracture mechanics approximations perhaps relevant to this setting, we additionally model both vertical and horizontal surface displacements and find rough agreement with the meter-scale displacements observed through GPS by Das et al. [Science, 2008].

  12. 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.

  13. 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

    ...Hydraulic Fracturing Research Advisory Panel...Agency (EPA) Science Advisory Board...Hydraulic Fracturing Research Advisory Panel...Fracturing on Drinking Water Resources: Progress...DFO), EPA Science Advisory Board...Environmental Research, Development...and drinking water. In 2011,...

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

    E-print Network

    Yang, Mei

    2011-10-21

    Hydraulic Fracturing is a technique to accelerate production and enhance ultimate recovery of oil and gas while fracture geometry is an important aspect in hydraulic fracturing design and optimization. Systematic design procedures are available...

  15. Effectiveness of Different Hydraulic Fracturing Treatments in Low Permeability Reservoirs

    Microsoft Academic Search

    Leo Schrider; C. D. Locke; R. D. Haynes

    1973-01-01

    Various hydraulic fracturing techniques have been used in the completion of oil wells in reservoirs that have low permeability. Reservoir information from over 100 wells in the same geographical area, such as production records, bottom-hole pressure buildup tests, and geophysical well logs were used to determine the effectiveness of different fracturing techniques. Two independent methods were used in the analysis,

  16. 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.

  17. Studying Hydraulic Fracturing through Time-variant Seismic Anisotropy

    E-print Network

    Liu, Qifan

    2013-10-01

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

  18. Locating microearthquakes induced by hydraulic fracturing in crystalline rock

    Microsoft Academic Search

    Leigh House

    1987-01-01

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

  19. 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.

  20. Hydraulic testing and modelling of a low-angle fracture zone at Finnsjön, Sweden

    NASA Astrophysics Data System (ADS)

    Andersson, J.-E.; Ekman, L.; Nordqvist, R.; Winberg, A.

    1991-08-01

    The hydraulic characteristics of a gently dipping fracture zone in crystalline rock at the Finnsjön test site in Sweden are described. The information is derived from single-hole injection tests of different packer spacings, including very detailed tests in 0.11-m sections in a few borehole segments. In addition, detailed hydraulic interference tests were performed by pumping in different parts of the zone and monitoring pressure changes in multiple-section observation boreholes. The results of the hydraulic testing show that the fracture zone is composed of two to five thin, highly conductive subzones in the boreholes; the uppermost subzone is consistently located close to the upper boundary of the major zone and can be correlated over several hundreds of metres. There is evidence of both lateral and vertical hydraulic anisotropy along the zone. The interference tests show that the fracture zone is delimited by semi-permeable boundaries, probably constituted by steeply dipping fracture zones. The results of the hydraulic testing are used to simulate the pressure responses obtained in the observation boreholes by numerical modelling.

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

    SciTech Connect

    Mineyuki Hanano; Tayuki Kondo

    1992-01-01

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

  2. Measurement of soil and rock fractural hydraulic conductivities using falling head infiltration experiment of single-ring permeameter

    NASA Astrophysics Data System (ADS)

    Chen, X.; Zhang, Z. C.; Shi, P.; Cheng, Q. B.

    2012-04-01

    Southwest China Karst is a fragile area for ecological system because of thin soil and underlying rock fracures. Soil and rock fractural hydraulic conductivities in this area determine infiltration, runoff and water retaining in soil and rock fractures for plant utilization. Determination of soil and rock fractural hydraulic conductivities is very tough due to strong heterogeneous. In this paper, we designed a single-ring permeameter to measure the hydraulic conductivities based on falling head infiltration experiment. The experiments were conducted in two karst areas in southwest China: a hillslope in Huanjiang County, northwest Guangxi for measuring soil hydraulic conductivities and a profile at the small catchment of Chenqi in the Puding basin of Guizhou for measuring fractural hydraulic conductivities. The results show that surface soil hydraulic conductivity is 2.386×10-4 m/s, much larger than 2.004×10-5 m/s for the soil at 30cm depth. Soil hydraulic conductivities are generally increased from the bottom to the top along the hillslope, and this increase is particularly significant for the soil at 30cm depth. The fractural hydraulic conductivities were determined for the limestone profile with three fractures crossing in vertical and horizontal directions. The effective fractural aperture was determined according to calibration of water head variations of the ponded water in the single ring permeameter, which can be simulated by a numerical model based on Navier-Stokes equations and measured with an automatic observation equipment. The hydraulic conductivities were then estimated in terms of the cubic law equation. The estimated effective fractural aperture is 0.25mm for the horizontal fracture, and 0.25 and 0.5mm for the two vertical fractures crossing the horizontal in the right and left sides, respectively. The corresponding hydraulic conductivity is 0.051 m/s for the horizontal fracture and 0.051 and 0.204m/s for the two vertical fractures in the right and left sides, respectively. Acknowledgments This research was supported by National Natural Science Foundation of China (No. 40930635, and 51079038)

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  4. 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

  5. 2006 GeoX Conference, pages 1 to 6 Characterisation of hydraulic fractures in

    E-print Network

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

  6. 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

  7. 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

  8. Estimating regional-scale fractured bedrock hydraulic conductivity using discrete fracture network (DFN) modeling

    NASA Astrophysics Data System (ADS)

    Voeckler, H.; Allen, D. M.

    2012-09-01

    Estimating bedrock hydraulic conductivity of regional fractured aquifers is challenging due to a lack of aquifer testing data and the presence of small and large-scale heterogeneity. This study provides a novel approach for estimating the bedrock hydraulic conductivity of a regional-scale fractured bedrock aquifer using discrete fracture network (DFN) modeling. The methodology is tested in the mountainous Okanagan Basin, British Columbia, Canada. Discrete fractures were mapped in outcrops, and larger-scale fracture zones (corresponding to lineaments) were mapped from orthophotos and LANDSAT imagery. Outcrop fracture data were used to generate DFN models for estimating hydraulic conductivity for the fractured matrix ( K m). The mountain block hydraulic conductivity ( K mb) was estimated using larger-scale DFN models. Lineament properties were estimated by best fit parameters for a simulated pumping test influenced by a fracture zone. Unknown dip angles and directions for lineaments were estimated from the small-scale fracture sets. Simulated K m and K mb values range from 10-8 to 10-7 m/s and are greatest in a N-S direction, coinciding with the main strike direction of Okanagan Valley Fault Zone. K mb values also decrease away from the fault, consistent with the decrease in lineament density. Simulated hydraulic conductivity values compare well with those estimated from pumping tests.

  9. 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

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

  10. Estimating fracture apertures from hydraulic data and comparison with theory

    SciTech Connect

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

    1985-01-01

    Estimates of fracture openings, or apertures, were made for massive hydraulic fracture experiments at the Hot Dry Rock geothermal reservoir at Fenton Hill, New Mexico. The basis of these estimates is that if the injection rate is suddenly increased during fracturing, and the subsequent pressure increase to sustain this additional flow is measured, then the pressure increase must be related to the fracture aperture. More detailed considerations indicate that the fracture aperture estimated in this manner is affected by the nature of the fracture geometry, its propagation distance, and its viscous characteristics, but these effects are surprisingly unimportant. The result is a reasonably accurate aperture estimate, which considering the elusive nature of this measurement by other means, is quite satisfactory. These estimates are in good agreement with the fracturing theory of Geertsma and de Klerk. 10 refs., 6 figs.

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

    USGS Publications Warehouse

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Shemeta, J. E.

    2011-12-01

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

  13. 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.

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

    E-print Network

    Wythe, Kathy

    2013-01-01

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

  15. 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

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

  16. 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

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

  17. Numerical Modeling of Hydraulic Fractures Interaction in Complex Naturally Fractured Formations

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  18. Occupational exposures to respirable crystalline silica during hydraulic fracturing.

    PubMed

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

    2013-01-01

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

  19. 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

  20. 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

  1. Experimental determination of hydraulic anisotropy in fractured formations

    SciTech Connect

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

    1994-09-01

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

  2. Interwell Tracer Analyses of a Hydraulically Fractured Granitic Geothermal Reservoir

    Microsoft Academic Search

    Jefferson Tester; Robert Bivins; Robert Potter

    1982-01-01

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

  3. 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 ...

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

    E-print Network

    Kamenov, Anton

    2013-04-11

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

  5. 75 FR 36387 - Informational Public Meetings for Hydraulic Fracturing Research Study; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-25

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

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

    E-print Network

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

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

    SciTech Connect

    Berryman, James G.

    2007-06-27

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

  8. 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.

  9. 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.

  10. Hydraulic Fracture Initiation and Propagation from Wellbore with Oriented Perforation

    NASA Astrophysics Data System (ADS)

    Zhu, Haiyan; Deng, Jingen; Jin, Xiaochun; Hu, Lianbo; Luo, Bo

    2015-03-01

    Considering the influence of casing, analytical solutions for stress distribution around a cased wellbore are derived, based on which a prediction model for hydraulic fracture initiation with the oriented perforation technique (OPT) is established. Taking well J2 of Z5 oilfield for an example, the predicted initiation pressure with the OPT of our model is about 4.2 MPa higher than the existing model, which neglects the influence of casing. In comparison with the results of laboratory fracturing experiments with OPT on a 400 × 400 × 400 mm3 rock sample for a cased well with the deviation of 45°, the fracture initiation pressure of our model has an error of 3.2 %, while the error of the existing model is 6.6 %; when the well azimuth angle is 0° and the perforation angle is 45°, the prediction error of the fracture initiation pressure of the existing model and our model are 3.4 and 7.7 %, respectively. The study verifies that our model is more applicable for hydraulic fracturing prediction of wells with OPT completion; while the existing model is more suitable for hydraulic fracturing with conventional perforation completion.

  11. 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.

  12. 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.

  13. Inverse modeling of the hydraulic properties of fractured media : development of a flow tomography approach

    NASA Astrophysics Data System (ADS)

    Bour, O.; Klepikova, M.; Le Borgne, T.; De Dreuzy, J.

    2013-12-01

    Inverse modeling of hydraulic and geometrical properties of fractured media is a very challenging objective due to the spatial heterogeneity of the medium and the scarcity of data. Here we present a flow tomography approach that permits to characterize the location, the connectivity and the hydraulic properties of main flow paths in fractured media. The accurate characterization of the location, hydraulic properties and connectivity of major fracture zones is essential to model flow and solute transport in fractured media. Cross-borehole flowmeter tests, which consist of measuring changes in vertical borehole flows when pumping a neighboring borehole, were shown to be an efficient technique to provide information on the properties of the flow zones that connect borehole pairs [Paillet, 1998; Le Borgne et al., 2006]. The interpretation of such experiments may however be quite uncertain when multiple connections exist. In this study, we explore the potential of flow tomography (i.e., sequential cross-borehole flowmeter tests) for characterizing aquifer heterogeneity. We first propose a framework for inverting flow and drawdown data to infer fracture connectivity and transmissivities. Here we use a simplified discrete fracture network approach that highlights main connectivity structures. This conceptual model attempts to reproduce fracture network connectivity without taking fracture geometry (length, orientation, dip) into account. We then explore the potential of the method for simplified synthetic fracture network models and quantify the sensitivity of drawdown and borehole flow velocities to the transmissivity of the connecting flowpaths. Flow tomography is expected to be most effective if cross-borehole pumping induces large changes in vertical borehole velocities. The uncertainty of the transmissivity estimates increases for small borehole flow velocities. The uncertainty about the transmissivity of fractures that connect the main flowpath but not the boreholes is generally higher. We demonstrate that successively changing pumping and observation boreholes improves the quality of available information and reduces the indetermination of the problem. The inverse method is validated for different synthetic flow scenarios. It is shown to provide a good estimation of connectivity patterns and transmissivities of main flowpaths. Although the chosen fracture network geometry has been simplified, flow tomography appears to be a promising approach for characterizing connectivity patterns and transmissivities of fractured media.

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

    Microsoft Academic Search

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

    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

  15. 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 Oðh� accuracy. For hydraulic fracture problems with a lag separating

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

    E-print Network

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

  17. 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

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

    E-print Network

    Peirce, Anthony

    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

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

    E-print Network

    Henderson, Gideon

    Oil and Gas CDT Quantification of hydraulic fracturing induced seismic risks using a probabilistic://www.pet.hw.ac.uk/staff-directory/mikechristie.htm Key Words Data Assimilation, Hydraulic fracturing, Seismic risk, Modelling errors, Uncertainty quantification Overview Hydraulic fracturing or "fracking" is a technique that uses fluids, pumped at high

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

    E-print Network

    Manning, Sturt

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

  1. 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

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

    E-print Network

    Mohaghegh, Shahab

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

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

    E-print Network

    Foulger, G. R.

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

  4. 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

  5. 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

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

    E-print Network

    Boyer, Edmond

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

  7. 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.

  8. 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...

  9. Monitoring the width of hydraulic fractures with acoustic waves

    Microsoft Academic Search

    Jeroen Groenenboom; Jacob T. Fokkema

    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

  10. FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS

    EPA Science Inventory

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

  11. 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...

  12. Identification of Successful Practices in Hydraulic Fracturing Using

    E-print Network

    Mohaghegh, Shahab

    1 Identification of Successful Practices in Hydraulic Fracturing Using Intelligent Data Mining a methodology to identify the successful practices in oil and gas related operations. Apply the methodology;SPE 77597, Mohaghegh, Popa, Gaskari, Ameri & Wolhart 6 METHODOLOGY The process of "Successful

  13. Fracture Toughness Evaluation Based on Tension-softening Model and its Application to Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Sato, Kazushi; Hashida, Toshiyuki

    2006-06-01

    This paper discusses the applicability of the tension-softening model in the determination of the fracture toughness of rocks, where the fracture toughness evaluated based on the tension-softening model is compared with the crack growth resistance deduced from laboratory-scale hydraulic fracturing tests. It is generally accepted that the fracture process is dominated by the growth of a fracture process zone for most types of rocks. In this study, the J-integral based technique is employed to determine the fracture toughness of Iidate granite on the basis of the tension-softening model, where compact tension specimens of different dimensions were tested in order to examine the specimen size effect on the measured fracture toughness. It was shown that the tension-softening relation deduced from the J-integral based technique allowed us to determine the specimen size independent fracture toughness K c of Iidate granite. Laboratory-scale hydraulic fracturing tests were performed on cubic specimens (up to a 10 m sized specimen), where cyclic pressurization was conducted using a rubber-made straddle packer to observe the extent of the hydraulically induced crack. The experimental results of pressure and crack length were then used to construct the crack growth resistance curve based on the stress intensity factor K. The crack growth resistance obtained from the hydraulic fracturing tests was observed to initially increase and then level off, giving a constant K value for a long crack extension stage. The plateau K value in the crack growth resistance curve was found to be in reasonable agreement with the fracture toughness K c deduced from the tension-softening relation. It was demonstrated that the tension-softening model provides a useful tool to determine the appropriate fracture toughness of rocks, which may be applicable for the analysis of the process of large-scale crack extension in rock masses.

  14. Measuring in situ vertical hydraulic conductivity in tidal environments

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    Microsoft Academic Search

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

    2003-01-01

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

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

    Microsoft Academic Search

    J. Geertsma; F. de Klerk

    1969-01-01

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

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

    E-print Network

    Alvarez Vera, Cesar

    2001-01-01

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

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

    E-print Network

    Li, Yingping

    1996-01-01

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

  19. Injection-Sensitive Mechanics of Hydraulic Fracture Interaction with Discontinuities

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  20. 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.

  1. 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.

  2. Evaluation of vertical variations in hydraulic conductivity in unconsolidated sediments.

    PubMed

    Dietze, Michael; Dietrich, Peter

    2012-01-01

    Detailed information on vertical variations in hydraulic conductivity (K) is essential to describe the dynamics of groundwater movement at contaminated sites or as input data used for modeling. K values in high vertical resolution should be determined because K tends to be more continuous in the horizontal than in the vertical direction. To determine K in shallow unconsolidated sediments and in the vertical direction, the recently developed direct-push injection logger can be used. The information obtained by this method serves as a proxy for K and has to be calibrated to obtain quantitative K values of measured vertical profiles. In this study, we performed direct-push soil sampling, sieve analyses and direct-push slug tests to obtain K values in vertical high resolution. Using the results of direct-push slug tests, quantitative K values obtained by the direct-push injection logger could be determined successfully. The results of sieve analyses provided lower accordance with the logs due to the inherent limitations of the sieving method. PMID:21883188

  3. Detection of Open Fractures with Vertical Seismic Profiling

    E-print Network

    Beydoun, W. B.

    1984-01-01

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

  4. Performance of petroleum reservoirs containing random vertical fractures

    E-print Network

    Huskey, William Lyman

    1963-01-01

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

  5. Distinct element modeling of hydraulically fractured Lac du Bonnet granite

    NASA Astrophysics Data System (ADS)

    Al-Busaidi, A.; Hazzard, J. F.; Young, R. P.

    2005-06-01

    The aim of this study is to better understand the mechanics of fracture development and propagation during hydraulic fracturing. This paper presents some development and applications of discrete particle modeling of this problem. A discontinuum modeling approach idealizes the material as separate particles bonded together at their contact points and utilizes the breakage of individual structural units or bonds to represent damage. The numerical models are correlated with existing hydrofracture laboratory experiments, which are presented in other publications. A simulation of a laboratory-scale hydrofracture experiment and the acoustic emission (AE) data from the experiment is used to validate the synthetic AEs produced in the hydrofracture model. This technique has been used to examine the mechanics of fracture initiation and time and spatial distributions of AE. The modeling results demonstrate that the mechanism of hydraulically induced fracture in the Lac du Bonnet (LdB) granite core sample is predominantly tensile failure and that the shear cracks recorded in the hydrofracture experiment were due to slip on preexisting fractures. Numerical modeling of hydrofracture on homogeneous and heterogeneous synthetic samples seems to capture much of the behavior observed in the laboratory hydrofracture experiments.

  6. 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.

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

    E-print Network

    Mishuris, Gennady; Linkov, Alexander

    2012-01-01

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

  8. 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

  9. Hydraulic fracturing with a refractory proppant combined with salinity control

    SciTech Connect

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

    1989-08-01

    This patent describes a method for controlling fines or sand in an unconsolidated or loosely consolidated formation, or reservoir which method additionally improves heat transfer. It comprises: placing at least one wellbore in the formation; hydraulically fracturing the formation via the wellbore via a fracturing fluid which creates at least one fracture; placing a fused refractory proppant consisting essentially of silicon carbide or silicon nitride into the fracture which proppant gravel packs the fracture while providing for increased heat transfer into the formation; determining the critical salinity rate and the critical fluid flow velocity of the formation or reservoir surrounding the wellbore; injecting a saline solution into the formation or reservoir at a velocity exceeding the critical fluid flow velocity and at a saline concentration sufficient to cause the fines or clay particles to be transferred and fixed deep within the formation or reservoir without plugging the formation, fracture or wellbore; and producing via a thermal oil recovery method a hydrocarbonaceous fluid from the formation or reservoir at a velocity such that the critical flow velocity is not exceeded deep within the formation, fracture or wellbore.

  10. Scintillation gamma spectrometer for analysis of hydraulic fracturing waste products.

    PubMed

    Ying, Leong; O'Connor, Frank; Stolz, John F

    2015-04-16

    Flowback and produced wastewaters from unconventional hydraulic fracturing during oil and gas explorations typically brings to the surface Naturally Occurring Radioactive Materials (NORM), predominantly radioisotopes from the U238 and Th232 decay chains. Traditionally, radiological sampling are performed by sending collected small samples for laboratory tests either by radiochemical analysis or measurements by a high-resolution High-Purity Germanium (HPGe) gamma spectrometer. One of the main isotopes of concern is Ra226 which requires an extended 21-days quantification period to allow for full secular equilibrium to be established for the alpha counting of its progeny daughter Rn222. Field trials of a sodium iodide (NaI) scintillation detector offers a more economic solution for rapid screenings of radiological samples. To achieve the quantification accuracy, this gamma spectrometer must be efficiency calibrated with known standard sources prior to field deployments to analyze the radioactivity concentrations in hydraulic fracturing waste products. PMID:25734826

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

    E-print Network

    Wang, Wenxin

    2006-04-12

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

  12. Hydraulic fracturing theory for conditions of thermal stress

    Microsoft Academic Search

    G. Stephens; B. Voight

    1982-01-01

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

  13. Mathematical modeling of hydraulic fracturing in coal seams

    SciTech Connect

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

    2005-02-01

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

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  16. 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

  17. 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 Ã? 2013 Published by Elsevier B.V. All rights reserved. 1. Introduction Hydraulic fractures (HF form 13 July 2013 Accepted 27 July 2013 Available online 20 August 2013 Keywords: XFEM Hydraulic

  18. 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

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

    Microsoft Academic Search

    Jonny Rutqvist; Chin-Fu Tsang; Ove Stephansson

    2000-01-01

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

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

    SciTech Connect

    Laue, M.L.

    1997-10-30

    This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well has been drilled. After pumping a remedial cement squeeze, all pay behind the 5 in. liner was perforated and stimulated. Once wellwork is complete for the existing perforations, a hydraulic fracture treatment will be pumped through a short interval of clustered perforations in the 7 in. liner. Following this frac, all pay behind the 7 in. liner will be perforated and completion operations will be final.

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

    NASA Astrophysics Data System (ADS)

    Burbey, T. J.; Zhou, X.

    2013-12-01

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

  2. Vertical hydraulic conductivity measurements in the Denver Basin, Colorado

    USGS Publications Warehouse

    Barkmann, P.E.

    2004-01-01

    The Denver Basin is a structural basin on the eastern flank of the Rocky Mountain Front Range, Colorado, containing approximately 3000 ft of sediments that hold a critical groundwater resource supplying many thousands of households with water. Managing this groundwater resource requires understanding how water gets into and moves through water-bearing layers in a complex multiple-layered sedimentary sequence. The Denver Basin aquifer system consists of permeable sandstone interbedded with impermeable shale that has been subdivided into four principle aquifers named, in ascending order, the Laramie-Fox Hills, Arapahoe, Denver, and Dawson aquifers. Although shale can dominate the stratigraphic interval containing the aquifers, there is very little empirical data regarding the hydrogeologic properties of the shale layers that control groundwater flow in the basin. The amount of water that flows vertically within the basin is limited by the vertical hydraulic conductivity through the confining shale layers. Low vertical flow volumes translate to low natural recharge rates and can have a profound negative impact on long-term well yields and the economic viability of utilizing the resource. To date, direct measurements of vertical hydraulic conductivity from cores of fine-grained sediments have been published from only five locations; and the data span a wide range from 1??10-3 to 1??10-11 cm/sec. This range may be attributable, in part, to differences in sample handling and analytical methods; however, it may also reflect subtle differences in the lithologic characteristics of the fine-grained sediments such as grain-size, clay mineralogy, and compaction that relate to position in the basin. These limited data certainly call for the collection of additional data.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  4. Page 1 of 5 Narrative Description of Hydraulic Fracturing Draft Regulations

    E-print Network

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

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

    Microsoft Academic Search

    Donald T. Secor; David D. Pollard

    1975-01-01

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

  6. Hydraulic fracturing with a refractory proppant for sand control

    SciTech Connect

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

    1989-04-04

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

  7. Method for enhancing heavy oil production using hydraulic fracturing

    SciTech Connect

    Jennings, A.R. Jr.; Smith, R.C.

    1991-04-09

    This patent describes a method for producing viscous substantially fines-free hydrocarbonaceous fluids from an unconsolidated or loosely consolidated formation. It comprises drilling into the formation at least one well into a first productive interval of the formation; fracturing hydraulically the well with a viscous fracturing fluid containing a proppant therein which is of a size sufficient to prop a created fracture and restrict fines movement into the fracture which proppant comprises silicon carbide, silicon nitride, or garnet; injecting a pre-determined volume of steam into the well in an amount sufficient to soften the viscous fluid and lower the viscosity of the fluid adjacent a fracture face producing the well at a rate sufficient to allow formation fines to build up on a fracture face communicating with the well thereby resulting in a filter screen sufficient to substantially remove formation fines from the hydrocarbonaceous fluids; injecting a second volume of steam into the well and producing substantially fines free hydrocarbonaceous fluids to the surface; repeating steps until a desired amount of hydrocarbonaceous fluids have been produced from the first interval; and isolating mechanically the first interval and repeating steps in a second productive interval of the formation.

  8. 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...

  9. 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.

  10. The Role of the Rock on Hydraulic Fracturing of Tight Shales

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    SciTech Connect

    Fritz, Brad G.; Mackley, Rob D.

    2008-12-13

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

  13. 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.

  14. Constraints on upward migration of hydraulic fracturing fluid and brine.

    PubMed

    Flewelling, Samuel A; Sharma, Manu

    2014-01-01

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

  15. Constraints on Upward Migration of Hydraulic Fracturing Fluid and Brine

    PubMed Central

    Flewelling, Samuel A; Sharma, Manu

    2014-01-01

    Recent increases in the use of hydraulic fracturing (HF) to aid extraction of oil and gas from black shales have raised concerns regarding potential environmental effects associated with predictions of upward migration of HF fluid and brine. Some recent studies have suggested that such upward migration can be large and that timescales for migration can be as short as a few years. In this article, we discuss the physical constraints on upward fluid migration from black shales (e.g., the Marcellus, Bakken, and Eagle Ford) to shallow aquifers, taking into account the potential changes to the subsurface brought about by HF. Our review of the literature indicates that HF affects a very limited portion of the entire thickness of the overlying bedrock and therefore, is unable to create direct hydraulic communication between black shales and shallow aquifers via induced fractures. As a result, upward migration of HF fluid and brine is controlled by preexisting hydraulic gradients and bedrock permeability. We show that in cases where there is an upward gradient, permeability is low, upward flow rates are low, and mean travel times are long (often >106?years). Consequently, the recently proposed rapid upward migration of brine and HF fluid, predicted to occur as a result of increased HF activity, does not appear to be physically plausible. Unrealistically high estimates of upward flow are the result of invalid assumptions about HF and the hydrogeology of sedimentary basins. PMID:23895673

  16. 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.

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

    E-print Network

    Linkov, Igor

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

  18. Predicting hydraulic tensile fracture spacing in strata-bound systems$ C.I. McDermott n

    E-print Network

    Haszeldine, Stuart

    Predicting hydraulic tensile fracture spacing in strata-bound systems$ C.I. McDermott n , K June 2013 Available online 15 July 2013 Keywords: Hydraulic fracturing Fracture spacing CO2 analogue that hydraulic fracturing can be expected in the lower layers of a caprock after a relatively short period

  19. 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...

  20. 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...

  1. 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.

  2. Hydraulic Fracturing, Wastewater Injection and Unintended Earthquakes (Invited)

    NASA Astrophysics Data System (ADS)

    Ellsworth, W. L.

    2013-12-01

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

  3. The Determination of Direction and Length Of Hydraulically Induced Fractures In Petroleum Reservoirs: A Field Experiment

    Microsoft Academic Search

    L. Z. Shuck

    1974-01-01

    The mechanics of hydraulic fracturing processes affecting the acoustic mapping of fractures, the associated crack and wave propagation phenomena, monitoring system requirements, an example of a monitoring system used, and field experiments conducted to date are discussed. Applications of the fracture mapping technique, if proven successful, could lead to improved well location design and fracturing treatments for more efficient petroleum

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  5. 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.

  6. 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

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

    EPA Science Inventory

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

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

    SciTech Connect

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

    2007-01-15

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

  9. Approach to estimating the maximum depth for glacially induced hydraulic jacking in fractured crystalline rock at Forsmark, Sweden

    NASA Astrophysics Data System (ADS)

    Lönnqvist, M.; Hökmark, H.

    2013-09-01

    Hydraulic jacking is a significant dilation of a fracture that occurs when the pore pressure within it exceeds the sum of the fracture's normal stress and tensile strength. This phenomenon may occur during a glacial period because of changes in hydraulic and mechanical boundary conditions. Since hydraulic jacking may alter flow patterns and the transport capacity of the rock mass, its possible effects on the long-term performance of a nuclear waste repository should be considered. We develop an approach to assess glacially induced hydraulic jacking in fractured crystalline rock and establish bounding estimates of the maximum jacking depth for the Swedish Nuclear Fuel and Waste Management Company's (SKB) repository site at Forsmark. The pore pressure is estimated using mechanically uncoupled two-dimensional poroelastic continuum models with hydraulic and mechanical conditions based on SKB's reconstruction of the Weichselian glaciation at this site (120-0 ka B.P.). For warm-based conditions, the water pressure at the ice/bed interface is set at 98% of the mechanical load, whereas for glacial conditions with extensive proglacial permafrost, the corresponding water pressure is set at a (lower) annual average value. We demonstrate that the pore pressure within the uppermost kilometer of rock is mainly governed by the water pressure at the ice/bed interface and that the mechanical impact of the ice load on the pore pressure is sufficiently small to be ignored. Given the current and estimated future stress conditions at Forsmark, hydraulic jacking is mainly of concern for subhorizontal fractures, i.e., it is sufficient to consider situations when the pore pressure exceeds the vertical stress. We conclude that hydraulic jacking at Forsmark will be confined to the uppermost 200 m of the rock mass.

  10. Fate of hydraulic fracturing chemicals under down-hole conditions

    NASA Astrophysics Data System (ADS)

    Blotevogel, J.; Kahrilas, G.; Corrin, E. R.; Borch, T.

    2013-12-01

    Hydraulic fracturing is a method to increase the yield of oil and natural gas extraction from unconventional rock formations. The process of hydrofracturing occurs via injecting water, sand, and chemicals into the production well and subjecting this mixture to high pressures to crack the rock shale, allowing increased amounts of gas and oil to seep out of the target formation. Typical constituents of the chemical mixtures are biocides, which are applied to inhibit growth of sulfate reducing bacteria in order to prevent pipe corrosion and production of hazardous gases. However, very little is known about the persistence, fate, and activity of biocides when subjected to the high temperatures and pressures of down-hole conditions. Thus, the objective of this talk is to present data from ongoing experiments focused on determining the fate of biocides commonly used for hydraulic fracturing under conditions simulating down-hole environments. Using stainless steel reactors, the high pressures and temperatures of down-hole conditions in the Marcellus shale are simulated, while concentration, speciation, and degradation of priority biocides are observed as a function of time, using primarily LC/MS techniques. The impact of water quality, shale, temperature, and pressure on the transformation kinetics and pathways of biocides will be discussed. Finally, field samples (both sediments and flowback brine) from the Marcellus shale are analyzed to verify that our lab simulations mirror real-life conditions and results.

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

    Microsoft Academic Search

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

    1993-01-01

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

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

    Microsoft Academic Search

    I. Berchenko; E. Detournay

    1997-01-01

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

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

    EPA Science Inventory

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

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

    E-print Network

    Paris-Sud XI, Université de

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

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

    EPA Science Inventory

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

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

    PubMed

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

    2003-01-01

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

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

    EPA Science Inventory

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

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

    USGS Publications Warehouse

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

    2000-01-01

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

  19. Hydraulic characterization for steam enhanced remediation conducted in fractured rock.

    PubMed

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

    2006-01-10

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

  20. Solution of hydraulic fracture problem accounting for lag

    E-print Network

    Linkov, Alexander M

    2014-01-01

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

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

    PubMed

    Ren, Lan; Zhao, Jinzhou; Hu, Yongquan

    2014-01-01

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

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

    PubMed Central

    Ren, Lan; Zhao, Jinzhou; Hu, Yongquan

    2014-01-01

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

  3. 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.

  4. 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

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

    NASA Astrophysics Data System (ADS)

    Cai, Zuansi; Ofterdinger, Ulrich

    2014-07-01

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

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

    SciTech Connect

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

    1992-10-01

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

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

    SciTech Connect

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

    1992-10-01

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

  8. Distinct Element Modelling of Hydraulically-Induced Fractures and Associated Seismicity

    NASA Astrophysics Data System (ADS)

    Al-Busaidi, A.; Hazzard, J.; Young, R. P.

    2003-04-01

    A new approach to simulating fracture nucleation is to model more fundamental elements of the rock (e.g. mineral grains) and to examine the effects of stress on the granular assembly. The main thrust of this research is to improve the current understanding of the mechanics of fracture development and propagation during hydraulic fracturing (HF) and to produce numerical models for hydro-fracture simulations using Itasca Consulting Group's Particle Flow Code (PFC2D). In these models fractures can start spontaneously and propagate outwards, unlike regular discontinuum modelling where slip can only occur on pre-defined planes. The Numerical Modelling package, PFC2D, is capable of doing this and takes into account the effect of the fracture process zone development during the hydraulic fracturing process. Microseismic (MS) monitoring is used in the oil industry (e.g., by PDO, Shell etc) to image the growth behaviour of hydraulic fractures. Numerical models of hydraulic fracture are a powerful method for predicting the geometry/orientation and to estimate the extent of fracturing. A simulation of a laboratory-scale hydrofracture experiment is presented and the acoustic emission (AE) data from the experiment is used to validate the synthetic AE's produced in the hydrofracture model. Future work will involve applying the validated modelling method to that of a full scale oil bearing hydraulic fracture network, and comparing the synthetic MS data to the recorded MS event distributions and source mechanisms.

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

    E-print Network

    Mohaghegh, Shahab

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

  10. Identification of Parameters Influencing the Response of Gas Storage Wells to Hydraulic Fracturing with the Aid of a Neural Network

    E-print Network

    Mohaghegh, Shahab

    75083-3836, U.S.A. Telex, 163245 SPEUT. Abstract Performing hydraulic fractures on gas storage wells necessary for most reservoir studies and hydraulic fracture design and evaluation are scarce for these old storage wells to hydraulic fracturing may be identified in the absence of sufficient reservoir data

  11. 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 scaling of hydraulic response to recharge in fractured aquifers: Insights from a frequency domain analysis

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

    E-print Network

    Jackson, Robert B.

    and Hydraulic Fracturing in the United States Avner Vengosh,*, Robert B. Jackson,, Nathaniel Warner,§ Thomas H: The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations

  13. 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.

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

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

    E-print Network

    Vallée, Martin

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

  15. 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

  16. 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

  17. 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

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  20. Sand control method employing special hydraulic fracturing technique

    SciTech Connect

    Medlin, W.L.; Mullins, L.D.; Zumwalt, G.L.

    1983-04-05

    A novel sand control method is disclosed wherein high viscosity, high sand concentration, fracturing fluids are pumped through sets of vertically oriented perforations in borehole casings located in unconsolidated or loosely consolidated pay zones. Various techniques are utilized to insure that sand fills disposed on either side of the borehole casing cover and substantially overlap each borehole casing perforation set. Procedures are then followed to bring the well into production without washing out the sand fills in these areas, whereby the resulting perforation-sand fill configurations effectively control sand production from the treated zone.

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

    E-print Network

    Paris-Sud XI, Université de

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

  2. Simplified hydraulic model of French vertical-flow constructed wetlands.

    PubMed

    Arias, Luis; Bertrand-Krajewski, Jean-Luc; Molle, Pascal

    2014-01-01

    Designing vertical-flow constructed wetlands (VFCWs) to treat both rain events and dry weather flow is a complex task due to the stochastic nature of rain events. Dynamic models can help to improve design, but they usually prove difficult to handle for designers. This study focuses on the development of a simplified hydraulic model of French VFCWs using an empirical infiltration coefficient--infiltration capacity parameter (ICP). The model was fitted using 60-second-step data collected on two experimental French VFCW systems and compared with Hydrus 1D software. The model revealed a season-by-season evolution of the ICP that could be explained by the mechanical role of reeds. This simplified model makes it possible to define time-course shifts in ponding time and outlet flows. As ponding time hinders oxygen renewal, thus impacting nitrification and organic matter degradation, ponding time limits can be used to fix a reliable design when treating both dry and rain events. PMID:25225940

  3. True vertical tooth root fracture: Case report and review

    PubMed Central

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

    2011-01-01

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

  4. 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.

  5. 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.

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

    PubMed

    Chai, Herzl; Tamse, Aviad

    2012-06-01

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

  7. 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.

  8. Constrained Hydraulic Fracture Optimization Improves Recovery from Low Permeable Oil Reservoirs

    Microsoft Academic Search

    M. M. Rahman

    2008-01-01

    The petroleum industry needs cost-effective hydraulic fracturing technique to increase recovery from low permeable reservoirs. That leads to the widespread use of various fracture optimization methods to find optimum values of controllable treatment design parameters. Inappropriate values of these parameters cause uncontrolled fracture, resulting in unnecessarily high treatment cost and finally low productivity. Application of the designed treatment parameters obtained

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

    Microsoft Academic Search

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

    2000-01-01

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

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

    Microsoft Academic Search

    Ren Jen Sun

    1969-01-01

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

  11. Massive Hydraulic Fracture Design for the East Texas Cotton Valley Sands

    Microsoft Academic Search

    Bernard Schlottman; William Miller II; R. K. Lueders

    1981-01-01

    The paper provides Amoco's current understanding of fracturing in the East Texas Cotton Valley Sands, outlines the massive hydraulic fracture (MHF) procedure used by Amoco, and documents the changes in the company's MHF stimulation designs in recent years. The subjects discussed include geology and reservoir properties; the effect of fracture length on gas recovery; leak-off control; pump rate scheduling; proppant

  12. Transient hydraulic fracturing and gas release in methane hydrate settings: A case study from southern Hydrate Ridge

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Bangs, Nathan L.; Dugan, Brandon

    2011-12-01

    Episodic seafloor methane venting is associated with focused fluid flow through fracture systems at many sites worldwide. We investigate the relationship between hydraulic fracturing and transient gas pressures at southern Hydrate Ridge, offshore Oregon, USA. Two colocated seismic surveys, acquired 8 years apart, at Hydrate Ridge show seismic amplitude variations interpreted as migration of free gas in a permeable conduit, Horizon A, feeding an active methane hydrate province. The geophysical surveys also reveal transients in gas venting to the water column. We propose that episodic gas migration and pressure fluctuations in the reservoir underlying the regional hydrate stability zone (RHSZ) at southern Hydrate Ridge influence methane supply to the RHSZ and are linked with periodic fracturing and seafloor methane venting. We model the effect of pore pressure variations within the deep methane source on fracturing behavior with a 1D model that couples multiphase flow, hydrate accumulation, and pore pressure buildup. As the reservoir pressure increases, fractures open when the pore pressure exceeds the hydrostatic vertical effective stress. Gas then flows through the fractures and vents at the seafloor while hydrate precipitates in the fracture system. We show that active seafloor gas venting occurs for approximately 30 years, and that the available methane reservoir is exhausted 30 to 55 years after the onset of pressure buildup. This provides important constraints on the time scale of transient fluid flow at southern Hydrate Ridge, and illustrates how pore pressure pulses affect fluid flow and fracturing behavior in active methane hydrate provinces.

  13. 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.

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

    Microsoft Academic Search

    Timothy T. Eaton; Kenneth R. Bradbury

    2003-01-01

    Hydraulic heads in a dolomitic shale bedrock aquitard in Wisconsin, USA, are apparently not in equilibrium with drawdown in the underlying aquifer system caused by pumping for municipal supply over the last century. Measurements of head with depth, downhole geophysical logs, and estimates of hydraulic conductivity indicate very low vertical hydraulic diffusivity, and show that high horizontal permeability within the

  15. Vertical arrays for fracture mapping in geothermal systems

    SciTech Connect

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

    1998-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Burden, Susan

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Urbancic, T.; Baig, A. M.

    2011-12-01

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

  18. 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.

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

    USGS Publications Warehouse

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

    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 2.66 MPa. The apparent direction of maximum compression is N 70?? E (??40??). At the San Ardo site the least principal stress is that due to the overburden weight. At depths of 240.2 and 270.7 m the minimum and maximum horizontal stresses are estimated to be 11.4 and 22.5 MPa, and 12.0 (??1.1) and 15.8 (??3.3) MPa, respectively. From an impression of the fracture at 240.2 m, the direction of maximum compression appears to be about N 15?? E. The rock in the Menlo Park well is too highly fractured to yield a reliable measurement of the horizontal stresses. The data indicate, however, that the least principal stress is vertical (due to the overburden weight) to a depth of 250 m. ?? 1977 Birkha??user Verlag.

  20. 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.

  1. Fluid flow and structural response modeling associated with the mechanics of hydraulic fracturing

    SciTech Connect

    Advani, S.H.; Lee, J.K.; Khattab, H.A.; Gurdogan, O.

    1986-06-01

    A review of hydraulic-fracture modeling is given. Equations governing pertinent fluid-flow, structural, and fracture-mechanics responses are presented. The finite-element method is used to discretize the field equations and to compute the fracture dimensions, fluid leakoff, and stress intensity factors. In addition, the effects of fracture-fluid properties, layered strata, and in-situ stresses are characterized, and numerical examples are presented.

  2. 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...

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

    NASA Astrophysics Data System (ADS)

    Jo, Y.; Chang, C.

    2013-12-01

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

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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.

  6. 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.

  7. Estimating spatially variable representative elementary scales in fractured architecture using hydraulic head observations

    NASA Astrophysics Data System (ADS)

    Wellman, Tristan P.; Poeter, Eileen P.

    2005-03-01

    Water resources within large-scale fractured aquifers are typically evaluated using continuum models. While any arbitrary scale of continuum can be imposed to represent fracture architecture, using the representative elementary volume eliminates errors that result from estimating network connectivity. In traditional theory, representative elementary scales (RES) are equal in magnitude and geometry throughout a domain and are normally determined using a structural indicator such as porosity or effective hydraulic conductivity. We present a fluid-based methodology, analyzing scale-dependent energy variation, to estimate RES using relatively low cost, readily available hydraulic head data. Hydraulic head predictions of RES (HYRES) reveal a spatial variation in elementary scale consistent with the flow field and fracture architecture. Porosity predictions of RES (PORRES) incorporate the structural effect of disconnected fracture regions but do not account for fluid behavior. RES estimated from hydraulic conductivity (KRES) are sensitive to fracture connectivity, which controls fluid movement, but are difficult to quantify because of scale and spatial variability. HYRES may be the superior approach for evaluating water resources because it is sensitive to fracture connectivity and avoids complications with scale and spatially dependent averaging. Our method is sensitive to fracture density, clustering, connectivity, and flow direction, but is insensitive to the magnitude of hydraulic gradient. HYRES is a novel approach to estimating spatially variable RES that improves water resource evaluation and flow characterization in fractured aquifers.

  8. 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 ...

  9. Integrated Hydraulic Fracture Placement and Design Optimization in Unconventional Gas Reservoirs

    E-print Network

    Ma, Xiaodan

    2013-12-10

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

  10. 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...

  11. Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

    EPA Science Inventory

    We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned toward conditions usually encountered in the Marce...

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. 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...

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

    E-print Network

    Dickins, Mark Ian

    2008-10-10

    THE IMPACT OF GRAVITY SEGREGATION ON MULTIPHASE NON-DARCY FLOW IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by MARK DICKINS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 2008 Major Subject: Petroleum Engineering THE IMPACT OF GRAVITY SEGREGATION ON MULTIPHASE NON-DARCY FLOW IN HYDRAULICALLY FRACTURED GAS WELLS A Thesis by MARK DICKINS...

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

    E-print Network

    Hresko, Joanne Carol

    1985-01-01

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

  17. Characterisation of hydraulic fractures in limestones using X-ray microtomography

    E-print Network

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

    2006-01-01

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

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

    E-print Network

    Kuzkin, Vitaly A; Linkov, Aleksandr M

    2013-01-01

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

  19. Physical Controls on Potential Upward Migration of Hydraulic Fracturing Fluid and Brine from Tight Oil and Gas Formations

    NASA Astrophysics Data System (ADS)

    Flewelling, S. A.; Tymchak, M. P.; Sharma, M.

    2013-12-01

    The widespread use of hydraulic fracturing (HF) has raised concerns about potential upward migration of HF fluid and brine through the rocks that overlay tight oil and gas formations (permeability ? 10-16 m2). The pathways along which potential fluid migration might occur include the primary porosity, induced and natural fractures, and preexisting faults. In this presentation, we evaluate the physical mechanisms that control whether HF fluid and brine can migrate upward along these pathways and, if so, the approximate magnitude of the fluxes and timescales over which such migration might occur. Our analysis focuses first on potential hydraulic communication between tight formations and shallow potable aquifers via induced fractures and preexisting faults. We developed a relationship that predicts maximum fracture height as a function of HF fluid volume and compared these predictions to the vertical extent of microseismicity from over 12,000 HF stimulations across North America. Virtually all microseisms were within the bounds of the theoretical relationship (a simple power law). The microseismic data were also used to estimate the size of shear displacement areas (including along preexisting faults), which were 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 and that direct hydraulic communication between tight formations and shallow potable groundwater via induced fractures and preexisting faults is not a realistic expectation. Apart from these pathways, the only other avenue for fluid migration is through the unmodified overlying rock. Due to the low permeability of targeted formations and surrounding strata, the pressure pulse applied during an HF stimulation is localized to the immediate vicinity of the fracture network and unable to drive large scale vertical flow. Thus, upward flow, if it occurs, would be controlled by the preexisting distribution of vertical permeabilities and head gradients. We show that in cases where there is an upward gradient, permeability is low, upward fluxes are low, and mean travel times are often greater than one million years. Consequently, it does not appear to be physically plausible for HF fluid and brine to migrate upward through overlying rock and affect shallow potable groundwater.

  20. Modeling of subsidence and stress-dependent hydraulic conductivity for intact and fractured porous media

    NASA Astrophysics Data System (ADS)

    Bai, M.; Elsworth, D.

    1994-10-01

    This study investigates the changes in deformation and stress dependent hydraulic conductivities that occur as a result of underground mining in intact and fractured porous media. The intact porous medium is assumed to be comprised of regularly packed spherical grains of uniform size. The variation in grain size or pore space due to the effect of changing intergranular stresses results in a change in rock hydraulic conductivity. A model is developed to describe the sensitivity of hydraulic conductivity to effective stresses through Hertzian contact of spherical grains. The fractured porous medium is approximated as an equivalent fracture network in which a single fracture is idealized as a planar opening having a constant equivalent thickness or aperture. Changes in fracture aperture as a result of changes in elastic deformation control the variation of hydraulic conductivity. A model is presented to illustrate the coupling between strain and hydraulic conductivity. Subsidence induced deformations that result from mining induced changes in hydraulic conductivity in both intact and fractured media. These changes are examined and compared with results from a mining case study.

  1. Texas review of hydraulic fracturing water use and consumption

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  2. Development of an Advanced Hydraulic Fracture Mapping System

    SciTech Connect

    Norm Warpinski; Steve Wolhart; Larry Griffin; Eric Davis

    2007-01-31

    The project to develop an advanced hydraulic fracture mapping system consisted of both hardware and analysis components in an effort to build, field, and analyze combined data from tiltmeter and microseismic arrays. The hardware sections of the project included: (1) the building of new tiltmeter housings with feedthroughs for use in conjunction with a microseismic array, (2) the development of a means to use separate telemetry systems for the tilt and microseismic arrays, and (3) the selection and fabrication of an accelerometer sensor system to improve signal-to-noise ratios. The analysis sections of the project included a joint inversion for analysis and interpretation of combined tiltmeter and microseismic data and improved methods for extracting slippage planes and other reservoir information from the microseisms. In addition, testing was performed at various steps in the process to assess the data quality and problems/issues that arose during various parts of the project. A prototype array was successfully tested and a full array is now being fabricated for industrial use.

  3. Selective oxidation of bromide in wastewater brines from hydraulic fracturing.

    PubMed

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

    2013-07-01

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

  4. Mechanical and hydraulic behavior of a rock fracture under shear deformation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    Microsoft Academic Search

    R. Carbonell; Jean Desroches; Emmanuel Detournay

    1999-01-01

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

  6. 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

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

    E-print Network

    Boyer, Edmond

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

  8. Comparison of Measured and Modelled Hydraulic Conductivities of Fractured Sandstone Cores

    NASA Astrophysics Data System (ADS)

    Baraka-Lokmane, S.; Liedl, R.; Teutsch, G.

    - A new method for characterising the detailed fracture geometry in sandstone cores is presented. This method is based on the impregnation of samples with coloured resin, without significant disturbance of the fractures. The fractures are made clearly visible by the resin, thus allowing the fracture geometry to be examined digitally. In order to model the bulk hydraulic conductivity, the samples are sectioned serially perpendicular to the flow direction. The hydraulic conductivity of individual sections is estimated by summing the contribution of the matrix and each fracture from the digital data. Finally, the hydraulic conductivity of the bulk sample is estimated by a harmonic average in series along the flow path. Results of this geometrical method are compared with actual physical conductivity values measured from fluid experiments carried out prior to sectioning. The predicted conductivity from the fracture geometry parameters (e.g., fracture aperture, fracture width, fracture length and fracture relative roughness all measured using an optical method) is in good agreement with the independent physical measurements, thereby validating the approach.

  9. Effect of Injected Water on Hydraulic Fracturing Deduced from Acoustic Emission Monitoring

    Microsoft Academic Search

    T. Ishida; Q. Chen; Y. Mizuta

    1997-01-01

    .  —In order to investigate the effects of injected water in hydraulic fracturing, experiments were conducted on cubic granite\\u000a specimens, comparing fracturings induced by conventional water injection with those induced by pressurization of a urethane\\u000a sleeve, thereby realizing \\

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

    SciTech Connect

    Advani, S.H.; Lee, J.K.; Khattab, H. [Dept. of Eng. Mechanics, Ohio State University Res. Foundation, Columbus, OH (United States)

    1985-05-01

    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.

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

    SciTech Connect

    Advani, S.H.; Lee, J.K.; Khattab, H. [Dept. of Eng. Mechanics, Ohio State University Res. Foundation, Columbus, OH (United States)

    1985-05-01

    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.

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

    Microsoft Academic Search

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

    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

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

    Microsoft Academic Search

    Norman Warpinski; Richard Schmidt; David Northrop

    1982-01-01

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

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

    Microsoft Academic Search

    David D. Pollard

    1976-01-01

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

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

    Microsoft Academic Search

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

    2000-01-01

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

  16. Microseismic mapping of a Cotton Valley hydraulic fracture using decimated downhole arrays

    Microsoft Academic Search

    J. T. Rutledge; W. S. Phillips; R. J. Zinno

    1998-01-01

    Summary An extensive microseismic data set was collected during three hydraulic fracture operations in the Cotton Valley gas field of East Texas. Two 48-level, 3-component geophone arrays were deployed. We have mapped the microseismicity of the Stage 2 completion interval using data from 9 or fewer geophone stations. Gross fracture dimensions obtained from the 9-station data were the same as

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

    E-print Network

    Daniels, Jeffrey J.

    for the interpretation of three-dimensional pneumatic well tests conducted in porous or fractured geologic media, which hydraulic conductivity and specific storage. Introduction Well test analyses in porous and fractured have a direct bearing on the field-scale prediction of ground water flow and contaminant transport

  18. An Investigation of Hydraulic Fracturing Initiation and Near-Wellbore Propagation from Perforated Boreholes in Tight Formations

    NASA Astrophysics Data System (ADS)

    Fallahzadeh, S. H.; Rasouli, V.; Sarmadivaleh, M.

    2015-03-01

    In this study, hydraulic fracturing tests were conducted on 10 and 15 cm synthetically manufactured cubic tight mortar samples. The use of cube samples allowed application of three independent stresses to mimic real far field stress conditions. A true triaxial stress cell was used for this purpose. The lab test parameters were scaled to simulate the operations at field scale. The hole and perforations were made into the sample after casting and curing were completed. Various scenarios of vertical and horizontal wells and in situ stress regimes were modeled. These factors are believed to play a significant role in fracture initiation and near-wellbore propagation behavior; however, they are not independent parameters, hence should be analyzed simultaneously. In addition to experimental studies, analytical solutions were developed to simulate the mechanism of fracture initiation in perforated boreholes in tight formations. Good agreements were observed between the experimental and analytical results. The results of this study showed that a lower initiation pressure is observed when the minimum stress component is perpendicular to the axis of the perforations. It was also seen that, even when the cement sheath behind the casing fails, the orientation of the perforations may affect the initiation of the induced fracture noticeably. Furthermore, it was found that stress anisotropy influences the fracturing mechanism in a perforated borehole, and affects the geometry of the initiated near-wellbore fracture.

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

    NASA Astrophysics Data System (ADS)

    Nicot, J.; Scanlon, B. R.

    2013-12-01

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

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

    PubMed

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

    2013-11-01

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

  1. Does hydraulic-fracturing theory work in jointed rock masses

    SciTech Connect

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

    1983-01-01

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

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

    SciTech Connect

    Hanson, M.; Towse, D.

    1982-04-14

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

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

    E-print Network

    Lumban Gaol, Ardhi

    2012-10-19

    D = dimensionless time tDA = dimensionless time with regard to reference drainage area u = Laplace parameter w = fracture width, L, ft xD = dimensionless point in x-direction xe = reservoir length, L, ft xf = fracture half length, L, ft x0... are assumed to be constant during depletion, the gravity effects being neglected. For the fractured well cases, the fluid is produced through the induced fractures with characteristics: fracture half length (xf), width (w), permeability (kf), and porosity...

  4. Fluid flow, structural, and fracture mechanics modeling associated with hydraulic stimulation operations

    SciTech Connect

    Advani, S.H.; Lee, J.K.; Hamid, M.S.; Gurdogan, O.; Khattab, H.

    1982-01-01

    A summary review of hydraulic fracture modeling is given. The equations governing pertinent fluid flow, structural, and fracture mechanics responses are presented along with salient assumptions. The finite element modeling approach is used to discretize the field equations and compute the fracture dimensions, fluid pressure profile, leak-off, and stress intensity factors. In addition, the effects of frac fluid properties, layered strata, in situ stresses, and bi-material interface characteristics are discussed and numerical examples are presented. 50 refs.

  5. 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.

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

    SciTech Connect

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

    2011-01-18

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

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

    USGS Publications Warehouse

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

    2002-01-01

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

  8. Acoustic emission in a fluid saturated heterogeneous porous layer with application to hydraulic fracture

    SciTech Connect

    Nelson, J.T. (California Univ., Berkeley, CA (USA). Dept. of Mechanical Engineering Lawrence Berkeley Lab., CA (USA))

    1988-11-01

    A theoretical model for acoustic emission in a vertically heterogeneous porous layer bounded by semi-infinite solid regions is developed using linearized equations of motion for a fluid/solid mixture and a reflectivity method. Green's functions are derived for both point loads and moments. Numerically integrated propagators represent solutions for intermediate heterogeneous layers in the porous region. These are substituted into a global matrix for solution by Gaussian elimination and back-substitution. Fluid partial stress and seismic responses to dislocations associated with fracturing of a layer of rock with a hydraulically conductive fracture network are computed with the model. A constitutive model is developed for representing the fractured rock layer as a porous material, using commonly accepted relationships for moduli. Derivations of density, tortuosity, and sinuosity are provided. The main results of the model application are the prediction of a substantial fluid partial stress response related to a second mode wave for the porous material. The response is observable for relatively large distances, on the order of several tens of meters. The visco-dynamic transition frequency associated with parabolic versus planar fluid velocity distributions across micro-crack apertures is in the low audio or seismic range, in contrast to materials with small pore size, such as porous rocks, for which the transition frequency is ultrasonic. Seismic responses are predicted for receiver locations both in the layer and in the outlying solid regions. In the porous region, the seismic response includes both shear and dilatational wave arrivals and a second-mode arrival. The second-mode arrival is not observable outside of the layer because of its low velocity relative to the dilatational and shear wave propagation velocities of the solid region.

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

    NASA Astrophysics Data System (ADS)

    Tsai, Victor C.; Rice, James R.

    2010-09-01

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

  10. Finite element modeling of hydraulic fracturing in 3D

    E-print Network

    2013-03-22

    Mar 22, 2013 ... the coupled system of equations. The fracture criterion ..... zero everywhere in the pore space. but non-zero at the fracture walls. ..... Y.: The transport properties of networks of crakcs and pores. ... the Soultz HDR site. Geophys.

  11. 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 on fluid flow is a...

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

    E-print Network

    Shabelansky, Andrey Hanan

    2012-01-01

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

  13. Test plan: Hydraulic fracturing and hydrologic tests in Marker Beds 139 and 140

    SciTech Connect

    Wawersik, W.R.; Beauheim, R.L.

    1991-03-01

    Combined hydraulic fracturing and hydrological measurements in this test plan are designed to evaluate the potential influence of fracture formation in anhydrite Marker Beds 139 and 140 on gas pressure in and gas flow from the disposal rooms in the Waste Isolation Pilot Plant with time. The tests have the further purpose of providing comparisons of permeabilities of anhydrite interbeds in an undisturbed (virgin) state and after fracture development and/or opening and dilation of preexisting partially healed fractures. Three sets of combined hydraulic fracturing and hydrological measurements are planned. A set of trial measurements is expected to last four to six weeks. The duration of each subsequent experiment is anticipated to be six to eight weeks.

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

    PubMed

    Torres, Sergio Andres Galindo; Castaño, Jose Daniel Muñoz

    2007-06-01

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

  15. Characterization of hydraulic fractures and reservoir properties of shale using natural tracers

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Gardner, P.; Kuhlman, K. L.; Malama, B.

    2013-12-01

    Hydraulic fracturing plays a major role in the economic production of hydrocarbon from shale. Current fracture characterization techniques are limited in diagnosing the transport properties of the fractures on the near wellbore scale to that of the entire stimulated reservoir volume. Microseismic reveals information on fracture geometries, but not transport properties. Production analysis (e.g., rate transient analysis using produced fluids) estimates fracture and reservoir flow characteristics, but often relies on simplified models in terms of fracture geometries and fluid storage and transport. We present the approach and potential benefits of incorporating natural tracers with production data analysis for fracture and reservoir characterization. Hydraulic fracturing releases omnipresent natural tracers that accumulate in low permeability rocks over geologic time (e.g., radiogenic 4He and 40Ar). Key reservoir characteristics govern the tracer release, which include: the number, connectivity, and geometry of fractures; the distribution of fracture-surface-area to matrix-block-volume; and the nature of hydrocarbon phases within the reservoir (e.g., methane dissolved in groundwater or present as a separate gas phase). We explore natural tracer systematics using numerical techniques under relevant shale-reservoir conditions. We evaluate the impact on natural tracer transport due to a variety of conceptual models of reservoir-transport properties and boundary conditions. Favorable attributes for analysis of natural tracers include the following: tracer concentrations start with a well-defined initial condition (i.e., equilibrium between matrix and any natural fractures); there is a large suite of tracers that cover a range of at least 7x in diffusion coefficients; and diffusive mass-transfer out of the matrix into hydraulic fractures will cause elemental and isotopic fractionation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Effects of various parameters on hydraulic fracture geometry. [Theoretical and experimental studies

    SciTech Connect

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

    1980-05-01

    Theoretical models have been applied to analyze some aspects of the dynamics of fracturing near material interfaces. Results of these calculations indicate that variation of material properties across a well bonded interface can cause dynamic material response resulting from the fracturing which could enhance propagation across the inerface. Effects of friction have also been analyzed theoretically; however, in the frictional calculations the wave mechanics have been ignored. These calculations have shown that frictional slip along the interface tends to draw a pressurized fracture toward the interface; this motion tends to reduce the chances of penetrating the material across the frictional interface. Small scale laboratory experiments are performed to study the effects of frictional characteristics on hydraulic fracture growth across unbonded interfaces in rocks. Various lubricants and mechanical preparation of the interface surfaces are used to vary the coefficients of friction on the interface surfaces. It is found that the frictional shear stress that the interface surface can support determines whether a hydraulically driven crack will cross the interface. Pre-existing cracks impede the propagation of the hydraulic fracture across the interface. These experimental results on the effects of friction on the interface and the effects of pre-existing cracks on hydraulic fracture penetration of interfaces are consistent with the predictions of the numerical model calculations. 11 figures.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

    The pneumatic fracturing technique is used to enhance the permeability and porosity of tight unconsolidated soils (e.g. clays), thereby improving the effectiveness of remediation treatments. Azimuthal self potential gradient (ASPG) surveys were performed on a compacted, unconsolidated clay block in order to evaluate their potential to delineate contaminant migration pathways in a mechanically-induced fracture network. Azimuthal resistivity (ARS) measurements were also made for comparative purposes. Following similar procedures to those used in the field, compressed kaolinite sediments were pneumatically fractured and the resulting fracture geometry characterized from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. We subsequently injected a simulated treatment (electrolyte/dye) into the fractures. Both ASPG and ARS data exhibit anisotropic geoelectric signatures resulting from the fracturing. Self potentials observed during injection of electrolyte are consistent with electrokinetic theory and previous laboratory results on a fracture block model. Visual (polar plot) analysis and linear regression of cross plots show ASPG lobes are correlated with azimuths of high fracture strike density, evidence that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. However, ARS data are uncorrelated with fracture strike maxima and resistivity anisotropy is probably dominated by enhanced surface conduction along azimuths of weak 'starter paths' formed from pulverization of the clay and increases in interfacial surface area. We find the magnitude of electrokinetic SP scales with the applied N2 gas pressure gradient (??PN2) for any particular hydraulically-active fracture set and that the positive lobe of the ASPG anomaly indicates the flow direction within the fracture network. These findings demonstrate the use of ASPG in characterizing the effectiveness of (1) pneumatic fracturing and (2) defining likely flow directions of remedial treatments in unconsolidated sediments and rock. ?? 2008 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2009-01-26

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

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

    SciTech Connect

    Berryman, J.G.

    2010-05-15

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2002-08-01

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

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

    USGS Publications Warehouse

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

    2002-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    SciTech Connect

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

    1997-09-01

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

  7. Determination of the length and compass orientation of hydraulic fractures by pulse testing

    E-print Network

    Manohar, Madan Mohan

    1984-01-01

    S3HAIDVHi OIlflVHOAH i0 NOIlVIN3IHO SSVHWOO QNV HlBN31 3Wl iO NOIlVNIWH3l30 DETERMINATION OF THE LENGTH AND COMPASS ORIENTATION OF HYDRAULIC FRACTURES BY PULSE TESTING A Thesis by MADAN MOHAN MANOHAR Approved as to Style and Content by: Wi... liam J. Lee (Ch ai rman of Commi t tee ) Le a M. Je Member) Richard A. Morse (Member) D. Yon Gonten ( d of Department) December 1984 ABSTRACT Determination of the Length and Compass Drientat1on of Hydraulic Fractures by Pulse Testing...

  8. Rock deformation models and fluid leak-off in hydraulic fracturing

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  9. HYDRAULIC CHARACTERIZATION FOR STEAM ENHANCED REMEDIATION CONDUCTED IN FRACTURED ROCK

    EPA Science Inventory

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

  10. Hydraulic fracturing in a sedimentary geothermal reservoir: Results and implications

    Microsoft Academic Search

    B. Legarth; E. Huenges; G. Zimmermann

    2005-01-01

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

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

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

    Chen, Qing

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

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

    USGS Publications Warehouse

    Hess, Alfred E.

    1986-01-01

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

  14. Pressure behavior of hydraulically fractured oil wells at and below the bubble-point pressure

    Microsoft Academic Search

    1985-01-01

    Pressure transient analysis is widely used by the oil industry to determine in-situ rock properties, wellbore damage, and apparent fracture length in hydraulically fractured wells. These rock properties are used by engineers to analyze reservoir performance and to predict future production. The mathematical development of pressure transient analysis theory assumes single-phase, constant-compressibility fluids flowing in a radial system. Pressure transient

  15. 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.

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

    E-print Network

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

  17. A Resolution of the First Unitarian Universalist Society of Albany to Oppose the Current Practice of Hydraulic Fracturing and Support the

    E-print Network

    Bystroff, Chris

    of Hydraulic Fracturing and Support the Widespread Adoption of Renewable Energy I. Whereas horizontal high-volume hydraulic fracturing ("fracking") is a recently- developed technology for extracting methane gas from shale Unitarian Universalist Society of Albany, New York is opposed to hydraulic fracturing in our community

  18. UK Oil and Gas Collaborative Doctoral Training Centre (2014 start) Project Title: Coupled flow of water and gas during hydraulic fracture in shale (EARTH-15-CM1)

    E-print Network

    Henderson, Gideon

    of water and gas during hydraulic fracture in shale (EARTH-15-CM1) Host institution: University of Oxford in extracting gas from these low-permeability rocks is hydraulic fracture. This involves injecting large of water and gas during hydraulic fracturing and subsequent gas recovery. This is essential in order

  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 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

  20. 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

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

    E-print Network

    Mohaghegh, Shahab

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

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

    NASA Astrophysics Data System (ADS)

    Sarmadivaleh, M.; Rasouli, V.

    2015-01-01

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

  3. Massive hydraulic fracture design for the east Texas Cotton Valley Sands

    SciTech Connect

    Schlottman, B.W.; Miller, W.K. III; Lueders, R.K.

    1981-01-01

    The paper provides Amoco's current understanding of fracturing in the East Texas Cotton Valley Sands, outlines the massive hydraulic fracture (MHF) procedure used by Amoco, and documents the changes in the company's MHF stimulation designs in recent years. The subjects discussed include geology and reservoir properties; the effect of fracture length on gas recovery; leak-off control; pump rate scheduling; proppant scheduling; gel selection; quality control; and equipment layout. Conclusions and/or recommendations relating to each subject are given aiming at more efficient MHF stimulations and increased gas recovery per well. 6 refs.

  4. Geomechanical model for fracture deformation under hydraulic, mechanical and thermal loads

    NASA Astrophysics Data System (ADS)

    McDermott, Chris; Kolditz, Olaf

    2006-04-01

    Hydraulic flow and transport (heat and solute) within crystalline rocks is dominated by the fracture systems found within them. In situ stress conditions have a significant impact on the hydraulic, mechanical and thermal coupled processes, and quantification of these processes provides a key to understanding the often transient time-dependent behaviour of crystalline rocks. In this paper, a geomechanical model is presented which describes fracture closure as a function of effective stress and the changes in parameters such as storage, permeability, porosity and aperture. Allowing the fracture closure to be defined by the change in normal effective stress provides a link to the numerical consideration of parametrical changes due to rock stress alterations caused for example by changes in fracture fluid pressure, stress release, tectonic stress, thermal stress, orientation of the natural fracture in the pervasive stress system and local changes in a rock mass due to stress alteration. The model uses geometrical considerations based on a fractal distribution of apertures on the fracture surface, and applies well-established analytical elastic deformation solutions to calculate the deformation response to changes in effective stress. Analysis of the fractal generation method allows a standard normal distribution of fracture apertures to be predicted for all common fractal dimensions relating to a 2D surface. Changes in the fracture aperture are related to hydraulic functions such as permeability, storage and porosity of the fracture. The geomechanical model is experimentally validated against laboratory scale experimental data gained from the closure of a fractured sample recovered at a depth of 3,800 m from the KTB pilot borehole. Parameters for matching the experimental data were established externally, the only fitting parameters applied were the minimum and maximum contact area between the surfaces and the number of allowable contacts. The model provides an insight into the key processes determining the closure of a fracture, and can act as a material input function for numerical models linking the effects of changes in the stress field, hydraulic or thermal conditions, to the flow and transport parameters of a fractured system.

  5. Explicit time-dependent solutions and numerical evaluations for penny-shaped hydraulic fracture models

    NASA Astrophysics Data System (ADS)

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

    1987-07-01

    The governing nonlinear equations for the hydraulically induced propagation of a circular crack in a poroelastic medium are derived. A Lagrangian formulation is utilized with the crack maximum width and radius selected as generalized coordinates. Explicit time-dependent solutions for the crack geometry and fluid pressure associated with Newtonian and non-Newtonian fracturing fluids are derived. The classical expression relating fracture width in terms of fracture radius is deduced as a special case. In addition, parameter sensitivity responses and comparison of results are presented.

  6. 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.

  7. Flow-Channeling in Fractured Bedrock: Combining GPR, Tracer, and Hydraulic Data

    NASA Astrophysics Data System (ADS)

    Becker, M. W.; Talley, J.; Baker, G. S.; Beyrle, N.

    2004-12-01

    Channeling of flow in a fracture plane has long been hypothesized, but never observed in map view. In a series of recent experiments, Ground Penetrating Radar (GPR) reflections were used to track the migration of saline tracer through a single saturated horizontal fracture in sandstone bedrock near Altona New York. Reflection amplitudes increased significantly in the presence of saline tracer. Tracer movement was mapped at multiple points in time over an approximately 100 square meter grid. Both forced and natural gradient transport experiments were conducted. In forced gradient experiments, saline tracer swept an area that was much smaller than would be predicted for a homogeneous conductivity field. Tracer also moved in a very heterogeneous manner under the influence of a natural hydraulic gradient. Hydraulic response in wells and tracer breakthrough compare favorably with the distribution of GPR-mapped saline fluid. These preliminary results suggest that the concept of channeled flow in rock fractures is valid, but specific channeling behavior is highly dependent upon hydraulic forcing. This combination of GPR, tracer, and hydraulic information may help develop better methods for measuring effective porosity through fractured bedrock.

  8. Water Value and Environmental Implications of Hydraulic Fracturing: Eagle-Ford Shale

    E-print Network

    Allen, W.; Lacewell, R.; Zinn, M.

    2014-01-01

    and is expected to be at 46% by 2035. Shale gas is considered to be one of the answers to the energy crisis. The goal of this research is to address several issues related to the efficacy of hydraulic fracturing of shale in deep formations to capture oil and gas...

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

    E-print Network

    Aderibigbe, Aderonke

    2012-07-16

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

  10. 78 FR 34611 - Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ...Part 3160 [WO-300-L13100000.FJ0000] RIN 1004-AE26 Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands...that usable water zones have been isolated and protected from contamination and more detailed guidance on how trade secrets claims...

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  12. Regulating hydraulic fracturing in shale gas plays: The case of Texas

    Microsoft Academic Search

    Dianne Rahm

    2011-01-01

    The ability to economically produce natural gas from unconventional shale gas reservoirs has been made possible recently through the application of horizontal drilling and hydraulic fracturing. This new technique has radically changed the energy future of the United States. The U.S. has shifted from a waning producer of natural gas to a growing producer. The Energy Information Administration forecasts that

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

    Microsoft Academic Search

    F. Rummel; R. Jung

    1975-01-01

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

  14. The crack tip solution for hydraulic fracturing in a permeable solid

    Microsoft Academic Search

    B. Lenoach

    1995-01-01

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

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

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

    USGS Publications Warehouse

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

    1994-01-01

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

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

    Microsoft Academic Search

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

    1985-01-01

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

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

    Microsoft Academic Search

    H. Abé; F. T. Mura; L. M. Keer

    1976-01-01

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

  19. Active and Passive Seismic Imaging of a Hydraulic Fracture in Diatomite

    Microsoft Academic Search

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

    1992-01-01

    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

  20. A Laboratory and Field Evaluation of a Technique for Hydraulic Fracturing Stimulation of Deep Wells

    Microsoft Academic Search

    Michael Conway; Lawrence Harris

    1982-01-01

    In 1981, over 1,000 new wells were drilled below 15,000 feet. Although bottom hole temperatures in these wells vary widely, all have a number of similar characteristics which make hydraulic fracturing treatments very difficult. The high treating pressures encountered necessitate the use of fluids with minimal pumping friction pressures. The high closure pressures often require the use of high strength

  1. 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

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

    Microsoft Academic Search

    Nancy C Carre

    2012-01-01

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

  3. Hydraulic Fracture Stimulation in a Fluid-filled Borehole via a TBEM Approach

    NASA Astrophysics Data System (ADS)

    Tadeu, A.; Antonio, J.; Mendes, P. A.; Sanchez-Sesma, F. J.

    2006-12-01

    In this paper, the Traction Boundary Element Method (TBEM) and the Boundary Element Method (BEM) are combined so as to evaluate the 3D wave field generated by 2D fluid-filled boreholes with a connecting hydraulic fracture. The problem is formulated in the frequency domain. The hydraulic fracture may exhibit arbitrary orientation and may present a very small thickness. The proposed formulation avoids the thin-body difficulty posed by the classical BEM formulation. All singular and hypersingular integrals are evaluated analytically, which overcomes one of the drawbacks of this formulation. Different source types such as 3D monopoles and dipoles loads may excite the borehole. The proposed model is first verified using a cylindrical circular fluid-filled borehole, for which analytical responses are known. Complex frequencies are used to avoid the aliasing phenomena in the time domain. The numerical results are analysed and a selection of spectra and animation plots from different hydraulic fracture configurations are presented. This allows the illustration of the significant scattered wave field modifications generated by a hydraulic fracture connected to the borehole.

  4. 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.

  5. 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.

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

    SciTech Connect

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

    1996-11-01

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

  7. 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.

  8. 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.

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

    PubMed

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

    2013-09-01

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

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

    Microsoft Academic Search

    Kazuo Hayashi; Bezalel C. Haimson

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hickman, S.; Davatzes, N. C.

    2009-12-01

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

  12. Upscaling of fracture hydraulics by means of an oriented correlated stochastic continuum model

    NASA Astrophysics Data System (ADS)

    Öhman, Johan; Niemi, Auli

    2003-10-01

    Two methods for upscaling hydraulics of fractured media are compared, namely, a classical fracture network based approach and a new enhanced stochastic continuum approach, the benefit of the latter being that while avoiding some of the complexities of fracture network models, it still can describe strong heterogeneity better than a classical stochastic continuum approach. In the continuum approach the fracture-induced heterogeneity is taken into account through an oriented, conductivity-dependent correlation structure. In addition, the radius of influence of the well tests is considered when assigning input conductivity statistics. The best fitting correlation structure of the continuum model is determined based on how well the results from the fracture network model can be reproduced. The results show that this best fitting correlation structure closely resembles in shape the probability distribution of fracture transmissivities. In other words, in the conductivity range where there is a large number of fractures in the fracture network model, large correlation lengths should be used in the stochastic continuum model, while the conductivity ranges with few fractures correspond to small correlation lengths in the stochastic continuum model.

  13. Micromechanical fracture modeling on underground nuclear waste storage: Coupled mechanical, thermal, and hydraulic effects

    NASA Astrophysics Data System (ADS)

    Leem, Junghun

    Coupling effects between thermal, hydraulic, chemical and mechanical (THCM) processes for rock materials are one of major issues in Geological engineering, Civil engineering, Hydrology, Petroleum engineering, and Environmental engineering. In all of these fields, at least two mechanisms of THCM coupling are considered. For an example, thermal, hydraulic, and mechanical coupling effects are important in Geological engineering and Civil engineering. The THM coupling produces effects on underground structures, since the underground structures are under influences of geothermal gradient, groundwater, gravitational stresses, and tectonic forces. In particular, underground repository of high-level nuclear waste involves all four of the THCM coupling processes. Thermo-hydro-mechanical coupling model for fractured rock media has been developed based on micromechanical fracture model [Kemeny 1991, Kemeny & Cook 1987]. The THM coupling model is able to simulate time- and rate-dependent fracture propagation on rock materials, and quantify characteristics of damage by extensile and shear fracture growth. The THM coupling model can also simulate coupled thermal effects on underground structures such as high-level nuclear waste repository. The results of thermo-mechanical coupling model are used in conducting a risk analysis on the structures. In addition, the THM coupling model is able to investigate variations of fluid flow and hydraulic characteristics on rock materials by measuring coupled anisotropic permeability. Later, effects of chemical coupling on rock materials are investigated and modified in the THM coupling model in order to develop a thermo-hydro-chemo-mechanical coupling model on fractured rocks. The THCM coupling model is compared with thermal, hydraulic, chemical, and mechanical coupling tests conducted at the University of Arizona. The comparison provides a reasonable prediction for the THCM coupling tests on various rock materials. Finally, the THCM coupling model for fractured rocks simulates the underground nuclear waste storage in Yucca Mountain, Nevada, and conducted performance and risk analysis on the repository.

  14. Measuring well hydraulic connectivity in fractured bedrock using periodic slug tests

    NASA Astrophysics Data System (ADS)

    Guiltinan, Eric; Becker, Matthew W.

    2015-02-01

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

  15. METHOD DEVELOPMENT FOR DETERMINING THE HYDRAULIC CONDUCTIVITY OF FRACTURED POROUS MEDIA

    SciTech Connect

    Dixon, K.

    2013-09-30

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

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

    NASA Astrophysics Data System (ADS)

    Wang, M.

    2001-05-01

    The hydraulic behavior of a fractured rock mass depends on the orientation, size, intensity, aperture, and connectivity of the fractures. The common assumption of fluid flow through a geologic continuum could be invalid for a fractured rock mass in a specified scale. Even though the Representative Elementary Volume (REV) is small for porous media, it is most likely much larger for fractured rock masses. The hydraulic behavior in a fractured rock mass may vary significantly even in a small scale. Therefore, it becomes very important to consider how to increase the efficiency and representative capability of packer tests in estimation of 3-D hydraulic conductivity tensor for a fractured rock mass. A structured approach is proposed to reach this goal. This approach is more applicable for a fractured rock mass where the flow field is dominated by fluid flow in a fracture network. First, the borehole for the packer test should allow for the acquisition of fracture information at different depths in order to perform fracture geometry modeling. This will entail the identification of statistically homogeneous depth ranges, delineation of fracture sets, and model validation. Software packages are available to analyze fracture data obtained from boreholes, which could be incorporated with the fracture data from scanlines and two-dimensional exposures. The aperture dimension and transmissivity of fractures should be accounted for during this identification. Hydraulic behaviors for each statistically homogeneous depth range can be evaluated by conducting packer tests in a typical interval. A stochastic fracture network is generated based on a built fracture geometry model in a cube of a specific size. The REV can be estimated using the directional hydraulic conductivity computed from a discrete fracture numerical flow model set up based on the stochastic fracture network and relative transmissivities for different fracture sets. Then, a Representative Elementary Length for the Test Interval along Borehole (RELTIB) needs to be estimated by conducting a number of computer stochastic simulations for intersections between different lengths of screen intervals along the borehole and fractures in the cube. RELTIB is achieved by selecting the minimum of the test interval lengths in which representative fracture features for each fracture set can be obtained. The packer tests should be performed along an interval with length dimension of RELTIB or longer to obtain representative hydraulic connection and other hydraulic attributes around the packer test borehole. For observation boreholes, an insufficient observation length could result in a lessened representative capability for hydraulic response due to the disconnection of fractures and detour of flow paths. Therefore, a Representative Elementary Length for the Observation Interval along Borehole (RELOIB) should be used to approximately obtain a point hydraulic response induced from the packer test. RELOIB can be investigated by performing a number of computer stochastic simulations for intersections between different lengths of observation intervals and fractures in the cube. Furthermore, REV should be referred in order to specify the locations of observation boreholes. Based on the packer test results through implementing the above structured approach for packer test design, the 3-D hydraulic conductivity tensor could be determined for a fractured rock mass using either a porous continuum method or discrete fracture flow approach.

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

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

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

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

    EPA Science Inventory

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

  19. Fracture studies from amplitude versus offset and azimuth and vertical seismic profile data 

    E-print Network

    Varela Gutierrez, Isabel

    2009-01-01

    In this thesis I address the problem of determining fracture properties of subsurface rocks from geophysical surface seismic and vertical seismic profile (VSP) data. In the first part of this thesis I perform multi-attribute ...

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    USGS Publications Warehouse

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

    1987-01-01

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

  2. 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.

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

    SciTech Connect

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

    2009-08-15

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

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

    SciTech Connect

    Shouchun Deng; Robert Podgorney; Hai Huang

    2011-02-01

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

  5. 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.

  6. 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.

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

    PubMed

    Murali Mohan, Arvind; 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. PMID:24088205

  8. 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.

  9. Enhanced detection of hydraulically active fractures by temperature profiling in lined heated bedrock boreholes

    NASA Astrophysics Data System (ADS)

    Pehme, P. E.; Parker, B. L.; Cherry, J. A.; Molson, J. W.; Greenhouse, J. P.

    2013-03-01

    SummaryThe effectiveness of borehole profiling using a temperature probe for identifying hydraulically active fractures in rock has improved due to the combination of two advances: improved temperature sensors, with resolution on the order of 0.001 °C, and temperature profiling within water inflated flexible impermeable liners used to temporarily seal boreholes from hydraulic cross-connection. The open-hole cross-connection effects dissipate after inflation, so that both the groundwater flow regime and the temperature distribution return to the ambient (background) condition. This paper introduces a third advancement: the use of an electrical heating cable that quickly increases the temperature of the entire static water column within the lined hole and thus places the entire borehole and its immediate vicinity into thermal disequilibrium with the broader rock mass. After heating for 4-6 h, profiling is conducted several times over a 24 h period as the temperature returns to background conditions. This procedure, referred to as the Active Line Source (ALS) method, offers two key improvements over prior methods. First, there is no depth limit for detection of fractures with flow. Second, both identification and qualitative comparison of evidence for ambient groundwater flow in fractures is improved throughout the entire test interval. The benefits of the ALS method are demonstrated by comparing results from two boreholes tested to depths of 90 and 120 m in a dolostone aquifer used for municipal water supply and in which most groundwater flow occurs in fractures. Temperature logging in the lined holes shows many fractures in the heterothermic zone both with and without heating, but only the ALS method shows many hydraulically active fractures in the deeper homothermic portion of the hole. The identification of discrete groundwater flow at many depths is supported by additional evidence concerning fracture occurrence, including continuous core visual inspection, acoustic televiewer logs, and tests for hydraulic conductivity using straddle packers as well as rock core VOC data, where available, that show deep penetration and many migration pathways. Confidence in the use of temperature profiles and the conceptual model is provided by numerical simulation and the demonstrated reproducibility of the evolution of the temperature signal measured in the lined holes with and without heating. This approach for using temperature profiling in lined holes with heating is a practical advance in fractured rock hydrogeology because the liners are readily available, the equipment needed for heating is low cost and rugged, and the time needed to obtain the profiles is not excessive for most projects.

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

    Microsoft Academic Search

    Peggy Rijken; Michele L. Cooke

    2001-01-01

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

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

    E-print Network

    Song, Fuxian

    2010-01-01

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

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

    E-print Network

    Turner, Daniel Z

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Alzarouni, Asim

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

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

    E-print Network

    Krawtz, John Paul

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Or, Dani; Tuller, Markus

    Standard models for hydraulic functions of partially saturated fractured porous media (FPM) often rely on macroscopic continuum representation and embrace constitutive relationships originally developed for homogeneous porous media to describe hydraulic behavior of dual (or multi) continua FPM. Such approaches lead to inconsistencies due to neglect of underlying physical processes governing liquid retention and flow in the vastly different pore spaces. We propose a framework that considers equilibrium liquid configurations in dual continuum pore space as the basis for calculation of liquid saturation and introduction of hydrodynamic considerations. FPM cross-sectional pore space is represented by a bimodal size distribution reflecting two disparate populations of matrix pores and fracture apertures (with rough-walled surfaces). Three laminar flow regimes are considered, flow in: (1) completely liquid filled pore spaces; (2) partially filled pores or grooves bounded by liquid-vapor interfaces; and (3) surface film flow. Assuming that equilibrium liquid-vapor interfaces remain stable under slow laminar flows, sample-scale unsaturated hydraulic conductivity is derived from average velocity expressions for each flow regime weighted by the appropriate liquid-occupied cross-sectional areas (neglecting 3-D network effects). A parameter estimation scheme was developed and evaluated using two data sets. The results point to the critical need for definitive data sets for improved understanding of flow in partially saturated FPM. Hydraulic conductivity functions for non-equilibrium conditions between matrix and fracture domains are discussed. Approximations for inclusion of network effects are proposed based on direct measurement of saturated hydraulic conductivity supplemented by theoretical considerations applying critical path analysis.

  17. Rock mechanics: Issues and research needs in the disposal of wastes in hydraulic fractures

    NASA Astrophysics Data System (ADS)

    Doe, T.; McClain, W. C.

    1984-07-01

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

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

    Microsoft Academic Search

    L. Zühlsdorff; V. Spieß

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lu, Rong

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

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

    PubMed Central

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

    2012-01-01

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

  1. Treatment of a vertical root fracture using dual-curing resin cement: a case report.

    PubMed

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

    2012-01-01

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

  2. Near-tip-screenout hydraulic fracturing of oil wells in the Bach Ho field, offshore Vietnam

    SciTech Connect

    Hung, L.V.; San, N.T.; Shelomentsev, A.G.; Tronov, J.A.; Lam, D.D.; Thomas, R.L.; Fox, T.; Bisdikian, C.

    1995-10-01

    The first hydraulic fracturing of wells in Vietnam were successfully performed Offshore in the Bach Ho (White Tiger) Oil Field. Near-tip-screenouts rather than tip-screenout treatments were performed. The goal of the project was to improve production from existing wells rather than drill new wells and reduce the cost per barrel produced. This case study involves wells with multiple perforated zones completed in the Oligocene sandstone. Zones were selectively fractured in order to optimize production. A detailed description candidate selection, design, execution and evaluation processes are presented. The Bach Ho field has been producing for 8 years but not at its potential due to various reasons including drilling and completion fluid damage. Although acidizing was an option for damage removal, hydraulic fracturing was selected as a way to bypass near-wellbore damage and generate a negative skin. Production simulators were used to quantify post-frac production. Due to suspected high closure stress, high strength proppant was selected and ramped in a high temperature fracturing fluid. Calibration treatments were conducted on several wells to quantify fluid leak-off, fracture height and Young`s modulus. Based on the results of the calibration treatment, fracture designs were modified. As predicted by computer simulation, near-tip-screenouts occurred as planned. The treatments were performed using a work boat with skid pumping/blending equipment, a computer monitoring/operation center and a laboratory. Strict QC procedures were followed to ensure the quality of all products. Post-frac well tests results and production data are presented. Overall, the fracturing campaign was very successful with wells showing negative skins and up to a five fold increase of production in agreement with systems analysis predictions.

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

    NASA Astrophysics Data System (ADS)

    Johnson, S.; Morris, J.

    2008-12-01

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

  4. Passive seismic monitoring of hydraulic fracture experiments at the Multiwell Experiment site

    SciTech Connect

    Thorne, B.J.; Morris, H.E.

    1988-08-01

    Redesign of hardware, software, and data-reduction techniques associated with the Sandia National Laboratories' Borehole Seismic System (BSS) have made possible better estimates of hydraulic fracture geometry at the Multiwell Experiment (MWX) site. The redesigned system now incorporates four geophones per axis and provides up to 112 dB of downhole gain, for 100 times the sensitivity of the original system. Improved signal-to-noise ratios, extended frequency response and increased digitization rates have made possible the acquisition and processing of data which were previously inaccessible. A maximum likelihood event location scheme, which incorporates an algorithm based on the use of spherical statistics, is used to compute the location of microseismic events and error estimates for these locations. Accuracy estimates for the redesigned system, based on the ability to locate perforation shots, indicates a 25 ft (7.6 m) uncertainty in the location of individual microseismic events using data from two BSS receivers. This resulted in a high level of confidence in determination of the azimuth of the November 1, 1986, hydraulic fracture in the Fluvial B sandstone. A reasonable determination of the azimuth, propped wing length and height for the September 23, 1987, hydraulic fracture in the Fluvial E sandstone was possible using data from only one BSS receiver. 15 refs., 32 figs., 6 tabs.

  5. 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.

  6. 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

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

    PubMed

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

    2014-10-01

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

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

    PubMed

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

    2014-11-01

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

  9. 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

  10. '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.

  11. The Determination of Tectonic Stresses through Analysis of Hydraulic Well Fracturing

    Microsoft Academic Search

    Ralph O. Kehle

    1964-01-01

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

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

    Microsoft Academic Search

    Shunji Sasaki

    1998-01-01

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

  13. Hydraulic and transport behavior of a variable aperture fracture by a transmitted-light optical measurement system

    NASA Astrophysics Data System (ADS)

    Sawada, A.; Sato, H.

    2009-12-01

    Safety assessment of radioactive waste disposal is mainly based on scenarios in which moving groundwater provides pathways for radionuclide migration from a waste repository to the surface environment. To evaluate groundwater flow and nuclide migration, an appropriate model capable of describing the characteristics of the host rock should be used. In the case of hard rock with low porosity such as granite, groundwater flow will be mainly through fractures. A single fracture is usually approximated by a parallel plate fracture model because of the lack of aperture data. A natural fracture, however, exhibits in-plane heterogeneity in terms of its variable aperture. Then there is need for a fundamental understanding of fluid flow in a fracture to provide a correlation between hydraulic and transport properties of the parallel plate model suitable to be used for modeling the behavior of a natural fracture. To this end, it is useful to obtain quantitative geometrical properties of the void space in a fracture and their relationship to hydraulic and transport properties. We have, therefore, measured both the fracture aperture distribution and the groundwater flow within the plane of a fracture, under the same condition as hydraulic tests, quantitatively by a transmitted-light optical measurement system applied to a transparent replica of a single fracture. The fracture replica is made by duplicating a tensile fracture that has been artificially generated in granite block at 10 cm scale with transparent resin. The transmitted-light intensity is attenuated depending on the light absorbance of dye, dye concentration and thickness filled with absorbing dye tracer as the light passes through it. The light intensity is measured by a high resolution and sensitive CCD (Charge Coupled Device) sensor. The data set of high spatial resolution aperture field in the fracture plane and the representative transmissivity obtained by hydraulic test are valuable to validate the accuracy of the local cubic law (LCL), which has been often used to examine fluid flow in variable aperture fractures. Recently, the adequacy of LCL for rough wall fractures has been examined by using Navier-Stokes (NS) fluid flow simulations on theoretical pattern of virtual fractures, virtually generated rough wall fractures and partially measured fracture pattern data. Our experimental study provides similar results as the NS simulation studies that a numerical calculation assuming LCL for a measured aperture field yields a fracture transmissivity about 1.7 times greater than the actual hydraulic test result.

  14. Edit paper Methods for Large Scale Hydraulic Fracture Monitoring

    E-print Network

    Ely, Gregory

    2013-01-01

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

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

    SciTech Connect

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

    1983-01-01

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

  16. 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

  17. 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.

  18. In-situ stresses: the predominant influence on hydraulic fracture containment

    SciTech Connect

    Warpinski, N.R.; Schmidt, R.A.; Northrop, D.A.

    1980-01-01

    In situ experiments, which are accessible by mineback, have been conducted to examine the parameters that control hydraulic fracture containment. These experiments show conclusively that material property differences at an interface are insufficient to arrest crack growth. Present models that predict the fracture should be contained at the interface because the stress intensity factor at the fracture tip goes to zero as the interface is approached are inadequate, and an improvement is suggested. However, sharp increases in the minimum principal in situ stress (as may occur at faults) and steep gradients in that stress have been shown to be effective barriers to crack propagation. Examples of fractures terminating at faults and parting planes illustrate how discontinuities in the in situ stress can arrest fracture growth. Furthermore, experiments were conducted in a formation which contained a steep gradient in the minimum principal in situ stress and which was overlain by a formation with a factor of five greater modulus. In each case, fractures were observed to terminate at regions of high minimum principal stress but to propagate readily into the higher modulus formation.

  19. Imaging of reservoirs and fracture systems using microearthquakes induced by hydraulic injections

    SciTech Connect

    Fehler, M.; House, L.; Phillips, W.S. (Los Alamos National Lab., NM (USA)); Block, L.; Cheng, C.H. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Earth Resources Lab.)

    1991-01-01

    Predicting the future performance of a geothermal reservoir and planning a strategy for increasing productivity from the reservoir require an intimate knowledge of the fracture system through which geothermal fluids permeate. Microearthquakes often accompany hydraulic fracturing as well as normal production activities in geothermal fields. The waveforms from the se microearthquakes provide valuable information that can be used to infer the three-dimensional structure of the fracture system in the reservoir. The locations of the microearthquakes can be used to infer the presence of large fractures along which shear slip has occurred. Tomographic imaging using arrival times of the seismic waves, provides a three-dimensional image of the P and S wave velocity structure of the reservoir. These velocities yield information about the presence of microfractures in the rock. Waveform stacking methods can be used to both corroborate seismic velocities and image seismic scatters in the reservoir. The most prominent seismic scatters are likely to be fluid-filled fractures. Thus, seismic data provide information about a fractures over a large scale range which can be of use in reservoir engineering. 32 refs., 4 figs.

  20. Advances in mathematical modeling of hydraulic stimulation of a subterranean fractured reservoir

    NASA Astrophysics Data System (ADS)

    Fomin, Sergei; Hashida, Toshiyuki

    2005-04-01

    Hydraulic stimulation is performed by a high-pressure fluid injection, which leads to a permanent increase in permeability of a volume of rock, typically transforming it from the microdarcy into the millidarcy range. The present paper provides an overview of the recent results in mathematical modeling of this process obtained at Tohoku University, Japan. Several mathematical models are proposed and realized. Within the steady-state approach, the geothermal reservoirs are characterized by parameters measured from field data and the model incorporates the approximations of the fracture mechanical behavior and fluid dynamics in fractured media. Along with the fractal-type distribution of the fracture lengths, the fracture surfaces are also assumed to follow fractal geometry. The latter allows numerical simulation of the natural rock fracture dilation caused by fracture shear offset. Recently, a new simplified non-steady mathematical model of the stimulation process was proposed. This model can be used for assessing the rate of the stimulated volume growth subject to injection pressure and flow rate and for approximate calculation of time required for creating the specified size of the stimulated region.

  1. Using Changes in Fracture Aperture During the Interpretation of Hydraulic Well Tests

    NASA Astrophysics Data System (ADS)

    Murdoch, L.; Schweisinger, T.; Svenson, E.; Germanovich, L.

    2003-12-01

    Fractures either dilate or contract in response to head changes during hydraulic well tests. We are measuring those changes in aperture in an effort to increase the information obtained from well tests. The measurements are made with a borehole extensometer temporarily anchored to the walls of an open borehole at two locations. An LVDT measures axial displacement between the anchors and those measurements are recorded along with pressure and temperature during a well test. Current investigations have focused on isolated flat-lying fractures, so axial displacements are assumed to equal changes in aperture. The current design of the extensometer can resolve displacements on the order of several tenths of a micron. Limiting sensitivity of the device to changes in temperature has been an important aspect of ensuring accuracy. Field tests are conducted on fractures identified using caliper and camera logs, and intact borehole intervals are tested for control. Preliminary tests have made use of a borehole cutting flat-lying fractures in biotite gneiss, where the fracture spacing and degree of weathering decreases with depth. Results show that the characteristics of the fractures change with depth: average normal compliance decreases from 0.5 micron/kPa to less than 0.05 micron/kPa, and the effective transmissivity decreases as depth increases from 23 m to 29 m. Normal compliance can be used to determine specific storage, suggesting that the displacement measurements can be used to determine aquifer storativity using a test conducted at a single well. Moreover, fracture compliance of the observed magnitudes implies that the fracture aperture, and thus the transmissivity, may change markedly during well tests where changes in head are significant. More detailed interpretations of the results are being made using a model that considers fluid flow along a deformable fracture embedded in porous material. Inverting the model using transient displacement data provides an approach for deriving information about the in situ dimensions and deformation characteristics of fractures that go beyond what can be determined from hydraulic measurements alone.

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

    Microsoft Academic Search

    Mark A. Meadows; D. F. Winterstein

    1994-01-01

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

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

    Microsoft Academic Search

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

    1982-01-01

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

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

    USGS Publications Warehouse

    Paillet, F.L.

    1993-01-01

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

  5. 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...

  6. 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.

  7. 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)…

  8. Measurement and analysis of fractures in vertical, slant, and horizontal core, with examples from the Mesaverde formation

    SciTech Connect

    Lorenz, J.C. (Sandia National Labs., Albuquerque, NM (United States)); Hill, R.E. (CER Corp., Las Vegas, NV (United States))

    1991-01-01

    Optimum analysis of natural fracture characteristics and distributions in reservoirs requires conscientious supervision of coring operations, on-site core processing, careful layout and marketing of the core, and detailed measurement of fracture characteristics. Natural fractures provide information on the in situ permeability system, and coring-induced fractures provide data on the in situ stresses. Fracture data derived from vertical core should include fracture height, type and location of fracture terminations with respect to lithologic heterogeneity, fracture planatary and roughness, and distribution with depth. Fractures in core from either a vertical or a deviated well will yield information on dip, dip azimuth, strike, mineralization, and the orientation of fractures relative to the in situ stresses. Only measurements of fractures in core from a deviated/horizontal well will provide estimates of fracture spacing and porosity. These data can be graphed and cross-plotted to yield semi-quantitative fracture characteristics for reservoir models. Data on the orientations of fractures relative to each other in unoriented core can be nearly as useful as the absolute orientations of fractures. A deviated pilot hole is recommended for fracture assessment prior to a drilling horizontal production well because it significantly enhances the chances of fracture intersection, and therefore of fracture characterization. 35 refs., 20 figs., 2 tabs.

  9. 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

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

    PubMed

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

    2014-06-01

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

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

    USGS Publications Warehouse

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  13. Well test analysis for wells with finite conductivity vertical fractures: application to the Upper Clearfork Formation

    E-print Network

    Santivongskul, Monton

    1992-01-01

    WELL TEST ANALYSIS FOR WELLS WITH FINITE CONDUCTIVITY VERTICAL FRACTURES: APPLICATION TO THE UPPER CLEARFORK FORMATION A Thesis by MONTON SANTIVONGSKUL Submitted to the Office of Graduate Studies of Texas A8tM University in paztial... fulfillment of the tequhettantts for the degree of MASTER OF SCIENCE August 1992 Major Subject: Petmleum Engineering WELL TEST ANALYSIS FOR WELLS W1TH FINTIX CONDUCITVITY VERTICAL FRACIURES: APPLICATION TO THE UPPER ~ORK FORMATION A Thesis by MONTON S...

  14. Use of a speed equation for numerical simulation of hydraulic fractures

    E-print Network

    Linkov, Alexander M

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

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

    PubMed

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

    2014-06-01

    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

  17. Modelling Hydraulic Fracture Breakdown, Shut-in, and Reopening for In Situ Stress Testing

    NASA Astrophysics Data System (ADS)

    Bunger, A. P.; Detournay, E.; Lakirouhani, A.

    2010-12-01

    Micro-hydraulic fractures have been widely and successfully used for characterisation of in situ stress for over 4 decades. Many field measurements, however, raise questions regarding the validity of the assumptions underlying the standard practice for analysis of field test data. Here we present a coupled numerical model that includes the compressibility of the injection system and the flow of a viscous fluid in a plane strain hydraulic fracture extending from a wellbore in the presence of a non-isotropic in situ stress field. Consistent with evidence from field data, this model predicts that with each injection cycle, the slope of the pressure versus time curve, before further crack extension takes place, will decrease. The pressure required for crack extension will also decrease with each injection cycle. Furthermore, the shut-in pressure is shown to essentially correspond to the pressure at which crack extension will commence on the next injection cycle, thus agreeing with the data compiled by Sano et al. (2005). Finally, the model demonstrates that the near-wellbore stresses, which also couple with the effects of compressibility and fluid viscous dissipation, lead to a difference of up to 50% between the peak wellbore pressure and the pressure at which the hydraulic fracture begins to grow. Ongoing work is aimed at quantitative re-interpretation of existing field data in light of these model results. The results of these simulations suggest that additional information could be extracted from the pressure-time record, if the characteristics of the injection cycles are properly chosen.

  18. 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.

  19. Numerical Simulation of 3D Hydraulic Fracturing Based on an Improved Flow-Stress-Damage Model and a Parallel FEM Technique

    NASA Astrophysics Data System (ADS)

    Li, L. C.; Tang, C. A.; Li, G.; Wang, S. Y.; Liang, Z. Z.; Zhang, Y. B.

    2012-09-01

    The failure mechanism of hydraulic fractures in heterogeneous geological materials is an important topic in mining and petroleum engineering. A three-dimensional (3D) finite element model that considers the coupled effects of seepage, damage, and the stress field is introduced. This model is based on a previously developed two-dimensional (2D) version of the model (RFPA2D-Rock Failure Process Analysis). The RFPA3D-Parallel model is developed using a parallel finite element method with a message-passing interface library. The constitutive law of this model considers strength and stiffness degradation, stress-dependent permeability for the pre-peak stage, and deformation-dependent permeability for the post-peak stage. Using this model, 3D modelling of progressive failure and associated fluid flow in rock are conducted and used to investigate the hydro-mechanical response of rock samples at laboratory scale. The responses investigated are the axial stress-axial strain together with permeability evolution and fracture patterns at various stages of loading. Then, the hydraulic fracturing process inside a rock specimen is numerically simulated. Three coupled processes are considered: (1) mechanical deformation of the solid medium induced by the fluid pressure acting on the fracture surfaces and the rock skeleton, (2) fluid flow within the fracture, and (3) propagation of the fracture. The numerically simulated results show that the fractures from a vertical wellbore propagate in the maximum principal stress direction without branching, turning, and twisting in the case of a large difference in the magnitude of the far-field stresses. Otherwise, the fracture initiates in a non-preferred direction and plane then turns and twists during propagation to become aligned with the preferred direction and plane. This pattern of fracturing is common when the rock formation contains multiple layers with different material properties. In addition, local heterogeneity of the rock matrix and macro-scale stress fluctuations due to the variability of material properties can cause the branching, turning, and twisting of fractures.

  20. 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.

    1992-01-01

    This study is a comparison of hydraulic-fracture models run using test data from the GRI Staged Field Experiment No. 3. Models compared include 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.