Fracture development in shale and its relationship to gas accumulation

Ding, Wenlong; Li, Chao; Li, Chunyan; Xu, Cheng; Jiu, Kai; Zeng, Weite; Wu, Li‐Ming

doi:10.1016/j.gsf.2011.10.001

Cited by 207 publications

(98 citation statements)

References 3 publications

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“…These discrepancies may be due to the dissipation of energy associated with mesoscale cracking which is not considered in this simulation. In shale rocks, significant amount of energy is dissipated in the fracture process zone and in the vicinity of the crack front (Ding et al 2012). In this simulation materials are considered to be fully brittle and the developed framework does not include a constitutive law for cohesive behavior of rock-like materials.…”

Section: Numerical Verificationmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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Reliable prediction of fracture process in shale-gas rocks remains one of the most significant challenges for establishing sustained economic oil and gas production. This paper presents a modeling framework for simulation of crack propagation in heterogeneous shale rocks. The framework is on the basis of a variational approach, consistent with Griffith's theory. The modeling framework is used to reproduce the fracture propagation process in shale rock samples under standard Brazilian disk test conditions. Data collected from the experiments are employed to determine the testing specimens' tensile strength and fracture toughness. To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on the fracture evolution. A parametric study has been carried out to better understand how anisotropy and heterogeneity of the mechanical properties affect both direction of cracks and rock strength.

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Section: Numerical Verificationmentioning

confidence: 99%

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

et al. 2018

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“…According to research findings, the existence of significant amounts of small clay particles causes reduced tensile and shear strength values, because clay particles obstruct stress transmission through the contact between quartz particles [19]. For this reason, clay-abundant shales mostly behave as ductile rock constituents with less brittleness [20,22]. The significant influence of clay particles on the mechanical properties of shale should be precisely understood in order to identify the long-term safety of the shale gas recovery process and the utilization of advanced shale gas recovery enhancement techniques such as hydro fracturing [69].…”

Section: Mechanical Properties Of Clay-abundant Shale Formationsmentioning

confidence: 99%

Characteristics of Clay-Abundant Shale Formations: Use of CO2 for Production Enhancement

et al. 2017

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Clay-abundant shale formations are quite common worldwide shale plays. This particular type of shale play has unique physico-chemical characteristics and therefore responds uniquely to the gas storage and production process. Clay minerals have huge surface areas due to prevailing laminated structures, and the deficiency in positive charges in the combination of tetrahedral and octahedral sheets in clay minerals produces strong cation exchange capacities (CECs), all of which factors create huge gas storage capacity in clay-abundant shale formations. However, the existence of large amounts of tiny clay particles separates the contacts between quartz particles, weakening the shale formation and enhancing its ductile properties. Furthermore, clay minerals' strong affinity for water causes clay-abundant shale formations to have large water contents and therefore reduced gas storage capacities. Clay-water interactions also create significant swelling in shale formations. All of these facts reduce the productivity of these formations. The critical influences of clay mineral-water interaction on the productivity of this particular type of shale plays indicates the inappropriateness of using traditional types of water-based fracturing fluids for production enhancement. Non-water-based fracturing fluids are therefore preferred, and CO 2 is preferable due to its many unique favourable characteristics, including its minor swelling effect, its ability to create long and narrow fractures at low breakdown pressures due to its ultralow viscosity, its contribution to the mitigation of the greenhouse gas effect, rapid clean-up and easy residual water removal capability. The aim of this paper is to obtain comprehensive knowledge of utilizing appropriate production enhancement techniques in clay-abundant shale formations based on a thorough literature review.

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“…tectonic stress field [80] [81] [82]. Due to remote effects of the Cenozoic India-Eurasia collision and subsequent continuous compression, the D gas field experienced a NNW-SSE compressional regime during the Himalayan period in the Kuqa Depression.…”

Section: Effect Of Stresses On Fracture Development and Distributionmentioning

confidence: 99%

Geomechanical Modeling of Stress and Fracture Distribution during Contractional Fault-Related Folding

Gu¹

2017

GEP

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Understanding and predicting the distribution of fractures in the deep tight sandstone reservoir are important for both gas exploration and exploitation activities in Kuqa Depression. We analyzed the characteristics of regional structural evolution and paleotectonic stress setting based on acoustic emission tests and structural feature analysis. Several suites of geomechanical models and experiments were developed to analyze how the geological factors influenced and controlled the development and distribution of fractures during folding. The multilayer model used elasto-plastic finite element method to capture the stress variations and slip along bedding surfaces, and allowed large deformation. The simulated results demonstrate that this novel Quasi-Binary Method coupling composite failure criterion and geomechanical model can effectively quantitatively predict the developed area of fracture parameters in fault-related folds. High-density regions of fractures are mainly located in the fold limbs during initial folding stage, then gradually migrate from forelimb to backlimb, from limbs to hinge, from deep to shallow along with the fold uplift. Among these factors, the fold uplift and slip displacement along fault have the most important influence on distributions of fractures and stress field, meanwhile the lithology and distance to fault have also has certain influences. When the uplift height exceeds approximately 55 percent of the total height of fold the facture density reaches a peak, which conforms to typical top-graben fold type with large amplitude and high-density factures in the top. The overall simulated results match well with core observation and FMI results both in the whole geometry and fracture distribution.

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Fracture development in shale and its relationship to gas accumulation

Cited by 207 publications

References 3 publications

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Characteristics of Clay-Abundant Shale Formations: Use of CO2 for Production Enhancement

Geomechanical Modeling of Stress and Fracture Distribution during Contractional Fault-Related Folding

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