Fracture Propagation Behavior of Jointed Rocks in Hydraulic Fracturing

Men, Xiaoxi; Li, Jiren; Han, Zheng‐Fu

doi:10.1155/2018/9461284

Cited by 8 publications

(6 citation statements)

References 33 publications

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“…Studies have shown that the spatial distribution and orientation of fault may or may not be the same as the associated joints (Cappa and Rutqvist 2011), but the existence of these discontinuities in different forms have an intrinsic influence on the numerical simulation for thermo-hydro-mechanical interactions. On a wider scale, it determines the expected hydraulic fractures emerging, and the overall recovery process (Men et al 2018). Many numerical and analytical solutions to both hydraulic fracturing problem and Enhanced Geothermal Systems have been proposed, and each of these has improved the understanding of the thermo-hydro-mechanical response of fault under injection, especially when it considers the influence of fracture geometry (Adachi et al 2007;Rutqvist et al 2013Rutqvist et al , 2015Yang and Zoback 2014;Jacquey et al 2015;Gan and Elsworth 2016a;Feng et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the influence of discontinuity orientations on fault permeability evolution and slip displacement

Eyinla

Gan

Oladunjoye

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

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A pre-existing plane of weakness along the fault is comprised of a particular pattern of joints dipping at different orientations. The fault stress state, partially defined by the orientation of fault, determines the potential of slip failure and hence the evolution of fault permeability. Here the influence of fault orientation on permeability evolution was investigated by direct fluid injection inside fault with three different sets of fault orientations (45°, 60° and 110°), through the coupled hydromechanical (H-M) model TOUGHREACT-FLAC3D. The influence of joints pattern on slip tendency and magnitude of potential induced seismicity was also evaluated by comparing the resulted slip distance and timing. The simulation results revealed that decreasing the dip angle of the fault increases the corresponding slip tendency in the normal fault circumstance. Also, with changing joints dip angle associated with the fault, the tendency of the fault slip changes concurrently with the permeability evolution in a noticeable manner. Permeability enhancement after the onset of fault slip was observed with the three sets of fault angles, while the condition of 60° dipping angle resulted in highest enhancement. Joints pattern with a dip angle of 145° (very high dip) and 30° (very low dip) did not trigger a shear slip with seismic permeability enhancement. However, high dip and intermediate dip angles (135°, 50° and 70°) yielded high permeability in varying orders of magnitude. The large stress excitation and increasing permeability during shear deformation was noticeably high in intermediate joint dip angles but decreases as the angle increases. Article highlights The magnitude of injection-induced permeability enhancement is largely influenced by the fault and joint spatial orientations. With a slight change in the joint direction, there is an increasing possibility for fault to approach a different critical state of failure. Stress elevation at the point of failure is controlled by the orientations of fault/joint planes with respect to the direction of maximum principal stress.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of the influence of discontinuity orientations on fault permeability evolution and slip displacement

Eyinla

Gan

Oladunjoye

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

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“…Knowing how a complex fracture network forms and how this network can improve reservoir permeability is an important research component of unconventional reservoir reconstruction [7,8]. Furthermore, discontinuities dominate the geometry, deformation modulus, strength, failure behavior, and permeability of rocks, and the existence of joints promotes the formation of complex fracture networks [9]. erefore, the study regarding the growth process of hydraulic fractures of jointed shale under different confining pressures is essential, as this topic is one of the important aspects of shale reservoir reconstruction research.…”

Section: Introductionmentioning

confidence: 99%

“…Heng et al [12] conducted threepoint bending tests of notched cylindrical specimens with different bedding orientations to investigate the influence of bedding planes on hydraulic fracture evolution. Men et al [9] numerically simulated the failure patterns and fracture propagation behavior of jointed rocks in hydraulic fracturing and found that the maximum principal stress and joint plane are the factors that control fracture propagation in the global and in local scales, respectively.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Hydraulic Fracture Evolution of Jointed Shale

Men

Jin

2021

Advances in Materials Science and Engineering

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Joints are a common structure of heterogeneous shale rock masses, and in situ stress is the environment in which heterogeneous rock masses can be found. The existence of joint plane and confining pressure difference influences the physical properties of shale and propagation of fractures. In this study, jointed shale specimens were simulated under different confining pressures to explore the failure patterns and fracture propagation behavior of hydraulic fracturing. Different from the common research of hydraulic fracturing on signal parallel joint rock mass, the simulations in this study considered three points (parallel joint, multi-dip angle joint, and no-joint points). The effects of the single-dip angle joint, multi-dip angle joint, and confining pressure difference on the hydraulic fracture evolution and stress evolution of the jointed shale were studied comprehensively. The confining pressure difference coefficient proposed in this study was used to accurately describe the confining pressure difference. Results indicate that the larger is the confining pressure difference, the stronger is the control of the maximum principal stress on fracture evolution; by contrast, the smaller is the confining pressure difference, the stronger is the control of the joint plane on fracture evolution. Under the same confining pressure difference, the hydraulic fracture propagates more easily along the small dip angle joint plane. As the value of the confining pressure difference coefficient moves closer to zero, the hydraulic fracture propagates randomly, the tensile stress region around the fracture tip widens, and the joint planes fractured by tensile increase. This study can offer valuable guidance to the design of unconventional reservoir reconstruction.

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“…A major setback in developing enhanced geothermal systems, shale gas, and tight hydrocarbon reservoir is the understanding of fracture network and possibilities of enhancing permeability of the fractured reservoir (Eshiet and Sheng 2017). Hence, knowledge of the variations in these properties is fundamental in characterising fractured reservoirs because they possess a direct correlation with the magnitude of fracture opening and production rate (Men et al 2018). The poroelastic effect caused by pressure build-up varies as the injection condition changes; consequently, when injecting into a low-permeable fault and fluid pressure is induced, the hydraulic diffusivity of the fluid pressure would be dependent on several factors such as the position of the injector, and the velocity of fluid transmission (Vilarrasa et al 2016;Eyinla et al 2020Eyinla et al , 2021aEyinla 2021;.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the influence of joint direction on production optimization in enhanced geothermal systems

Eyinla

2021

J Petrol Explor Prod Technol

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Heat extraction from geothermal reservoir by circulating cold water into a hot rock requires an amount of fluid pressure, which is capable of inducing fault opening. Although stress change promotes the potential of fault failure and reactivation, the rate at which fluid pressurization within the fault zone generates variations in pore pressure as fault geometry changes during geothermal energy production have not been thoroughly addressed to include the effects of joint orientation. This study examines how different fault/joint models result in different tendency of injection-induced shear failure, and how this could influence the production rate. Here, a numerical simulation method is adopted to investigate the thermo-hydro-mechanical (THM) response of the various fault/joint models during production in a geothermal reservoir. The results indicate that pore pressure evolution has a direct relationship with the evolution of production rate for the three joint models examined, and the stress sensitivity of the individual fault/joint model also produced an effect on the production rate. Changing the position of the injection well revealed that the magnitude of shear failure on the fault plane could be controlled by the hydraulic diffusivity of fluid pressure, and the production rate is also influenced by the magnitude of stress change at the injection and production wells. Overall, the location of the injection well along with the fault damage zone significantly influenced the resulting production rate, but a more dominating factor is the joint orientation with respect to the maximum principal stress direction. Thus, the rate of thermal drawdown is affected by pore pressure elevation and stress change while the fault permeability and the production rate are enhanced when the joint’s frictional resistance is low.

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Fracture Propagation Behavior of Jointed Rocks in Hydraulic Fracturing

Cited by 8 publications

References 33 publications

Numerical investigation of the influence of discontinuity orientations on fault permeability evolution and slip displacement

Numerical investigation of the influence of discontinuity orientations on fault permeability evolution and slip displacement

Numerical Investigation on the Hydraulic Fracture Evolution of Jointed Shale

Analysis of the influence of joint direction on production optimization in enhanced geothermal systems

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