Impacts of bedding directions of shale gas reservoirs on hydraulically induced crack propagation

Sun, Ke; Zhang, Shucui; Xin, Liwei

doi:10.1016/j.ngib.2016.03.008

Cited by 21 publications

(11 citation statements)

References 4 publications

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“…However, the main issue with DEM model is the computational cost, which becomes prohibitive if largescale problems need to be analyzed. Classical finite element method (FEM) (Dokhani et al 2016;Zeng and Wei 2017) and extended FEM (Sun et al 2016) have been successfully applied to fracture propagation and fracking simulations on shale rocks. Anisotropy has been included in some of these numerical simulations by decreasing the values of mechanical properties, such as elastic modulus, cohesion coefficients or fracture toughness, in precise locations of the domain in order to create weak layers which affect fracture extents and shapes.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…For the same rock sample, the relaxation rate ρ 2 and pore shape factor F S can be approximated as constants. Hence, the T 2 spectra can be used to determine the distribution of rock pores because rocks with longer relaxation times correspond to larger fractures, and vice versa [52,53].…”

Section: Nuclear Magneticmentioning

confidence: 99%

“…Bedding fractures are related to tectogenesis. Because beddings are the weak surfaces of strata, when the pressure gradient inside a closed system is greater than a critical value, a part of the bedding surface dislocates or opens to form a fracture [52,56]. Bedding fractures are nearly parallel to the bedding surface and cross mineral grains.…”

Section: Genetic Types Of Microfracturesmentioning

confidence: 99%

Genetic Types and Main Control Factors of Microfractures in Tight Oil Reservoirs of Jimsar Sag

et al. 2021

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Microfractures are key for migrating and aggregating hydrocarbon source rocks and fracturing oil-gas exploitation in tight reservoirs. In this study, rock samples from the Lucaogou Formation tight reservoirs in Xinjiang, China, were studied using multidisciplinary techniques to investigate the genetic types and main control factors of microfractures. Results indicated that the Lucaogou Formation mainly developed diagenetic microfractures followed by tectonic microfractures, with slight formations of granular microfractures. These observations were used to clarify the relationship between the development of microfractures and the pore fluid content, lithology, mineral composition, and stratum thickness. A higher pore fluid content corresponded to a lower compressive strength of the rocks and a larger ring count, resulting in a higher probability of failure and microfracture formation. Tight reservoirs containing more quartz and carbonate minerals were found to develop more microfractures. Quartz grains showed fractures at the margins under stress, which increased the pore permeability of rocks. Carbonate minerals tended to form microfractures owing to corrosion. Microfracture formation mechanisms differed depending on lithology, and microfractures were found to develop most in dolomite and dolomitic siltstones and least in mudstone. Muddy rocks developed fewer tectonic fractures because they can easily absorb stress and undergo plastic deformation. Within a certain stratum thickness range, the average single-well fracture space and stratum thickness showed positive correlations. Moreover, the fracture space increased and the fracture density decreased as the stratum thickness increased. When the stratum thickness was less than 2.5 m, the fracture space increased linearly with the stratum thickness, and when the stratum thickness was greater than 2.5 m, the fracture space remained constant. This study will provide an essential scientific basis for enhancing tight oil recovery.

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“…rock mechanics and hydraulic fracturing studies that show the bedding plane direction is generally weaker than the plane perpendicular to the bedding plane (Dyskin et al, 1991;Sun et al, 2016;Zhang et al, 2014), due to anisotropy resulting from the depositional environment and tectonic stresses as coal is formed. developed in coal #2 after EHD stimulation and that the fractures penetrate through the coal cube.…”

Section: Characterisation Of Coal After Ehd Stimulationmentioning

confidence: 99%

Characterisation and evaluation of shockwave generation in water conditions for coal fracturing

Ren

Stelmashuk

et al. 2019

Journal of Natural Gas Science and Engineering

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Impacts of bedding directions of shale gas reservoirs on hydraulically induced crack propagation

Cited by 21 publications

References 4 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

Genetic Types and Main Control Factors of Microfractures in Tight Oil Reservoirs of Jimsar Sag

Characterisation and evaluation of shockwave generation in water conditions for coal fracturing

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