Change in the permeability of clastic rock during multi-loading triaxial compressive creep tests

Zhang, Yanzhen; Liu, Zaobao; Xu, Weiya; Shao, Jian-Fu

doi:10.1680/jgele.15.00029

Cited by 20 publications

(8 citation statements)

References 17 publications

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“…Permeability test was conducted in a manner similar to a normal triaxial compression test under drained conditions at room temperature (25±1.5 °C) (Zhang et al, 2015;Zhang et al, 2016). The confining pressure and axial stress were imposed at a constant rate of 0.75 MPa/min and the liquid medium used was conducted to estimate the permeability behaviour of a fractured rock under triaxial loading conditions.…”

Section: Methodsmentioning

confidence: 99%

Experimental investigation on permeability in fractured rock under different pressure conditions

Zhang¹

2021

Acta Geodynamica Et Geomaterialia

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Oil and gas are the main reserves in the fractures of rocks. Under different pressure conditions, fracture permeability of reservoir rock directly affects the flow of oil and gas, which is an important object of oil and gas exploration and development. The permeability of single fractured rock and double fractured rock under different pressure conditions was studied by using highprecision hydro-mechanics coupled triaxial experimental equipment. The experimental scheme is as follows: (i) permeability test under increasing confining pressure, (ii) permeability test under increasing liquid pressure, (iii) permeability test under cyclic loading and unloading deviatoric stress and (iv) permeability test under synchronously increasing confining pressure and deviatoric stress. Results show that the entire change of permeability is irreversibly reduced. This is due to the presence of residual factors in permeability after the dilation cycle and the recompaction cycle ends. On the basis of the dual medium model of fracture, the permeability model of fractured rock is proposed considering the interaction among fracture system, matrix system and expansion deformation of fracture under external stress. The simulation results of the model are in good agreement with the experimental results. These results can provide an important basis for the prediction of permeability of fractured rock and efficient oil and gas exploitation.

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Section: Methodsmentioning

confidence: 99%

Experimental investigation on permeability in fractured rock under different pressure conditions

Zhang¹

2021

Acta Geodynamica Et Geomaterialia

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“…For granite, Chen [17] revealed that the permeability decreases when confining pressure is larger and increases when pore water pressure is larger under compressive stress conditions. Yi et al [18], Heiland and Raab [19], Alam et al [20], and Zhang et al [21] studied permeability evolution of different rock types under compression. The results show similar permeability evolution trends, in which the permeability decreases at the stage of volumetric compaction and increases at the stage of volumetric dilation.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Hydromechanical Coupled Deformation Behavior of Beishan Granite considering Permeability Evolution

et al. 2020

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Beishan granite is a potential host rock for a high-level radioactive waste (HLW) repository in China. Understanding the hydromechanical (HM) behavior and permeability evolution of Beishan granite is important for the HLW repository safety. Therefore, the granite of Beishan in Gansu province was studied. HM coupled tests are carried out on Beishan granite under different pore pressures. The results show that the initial pressure difference has little influence on permeability measurement before dilatancy starts. However, after onset of dilatancy, the permeability increases with the increasing initial pressure difference. The initial permeability of Beishan granite is about 10−18 m2 under a confining pressure of 20 MPa. In the initial loading phase, the permeability shows a relatively large reduction. Then, the permeability almost keeps constant until dilatancy starts. From dilatancy point to peak stress, permeability increases linearly with volumetric strain. The proposed permeability evolution rule is implemented into a numerical code to perform HM coupled simulations. The simulation results show that the damaged zone first appears at the model boundary and then extends to the inside, forming high volumetric strain areas. And it provides seepage channels for fluid flow. The macroscopic fracture patterns indicate that pore pressure accelerates rock degradation during HM coupling. The obtained results help to understand the damage mechanisms of granite caused by pore pressures and are of great importance for the safety of a HLW repository.

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“…The internal structure is subject to plastic deformation and damage evolution, which leads to the degradation of the mechanical property. Therefore, the strength of the clastic reservoir is evidently reduced, thereby causing casing damage and a large deformation of the reservoir [9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behavior of Coupled Elastoplastic Damage of Clastic Sandstone of Different Burial Depths

Wang

Zhang

2020

Energies

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Clastic sandstone is widely distributed in oil and gas reservoirs; its internal structure has many micro-defects. Under different stress environments of burial depth, significant damage evolution and plastic deformation easily occur. A series of triaxial compression tests were performed to study the coupled elastoplastic damage mechanical behavior of clastic sandstone samples at different burial depths ranging from 581.28 m to 979.82 m. Results reveal that the stress-strain responses of clastic sandstone samples exhibit significant nonlinear and softening characteristics. The mechanical behavior is due to the coupling of plastic deformation and mechanical damage. Plastic and damage internal variables cause damage stiffness degradation and plastic flow. Considering the coupling of elastoplastic damage in the loading process, an elastoplastic damage coupling model is proposed to study the mechanical behavior of different burial depth clastic sandstones. The model can effectively describe the mechanical behavior of clastic sandstone, such as the volume compression and dilatancy transformation, plastic hardening and damage softening, which are in good agreement with the experimental results. Furthermore, the mechanical behavior of the clastic sandstone shows a dependency on the confining pressure and burial depth. The load-bearing capacity and the ability to resist deformation of the clastic sandstone are improved as the confining pressure and burial depth increase. Relevant results can provide reliable basis for the safe exploitation of oil and gas engineering.

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Change in the permeability of clastic rock during multi-loading triaxial compressive creep tests

Cited by 20 publications

References 17 publications

Experimental investigation on permeability in fractured rock under different pressure conditions

Experimental investigation on permeability in fractured rock under different pressure conditions

Experimental and Numerical Study on Hydromechanical Coupled Deformation Behavior of Beishan Granite considering Permeability Evolution

Mechanical Behavior of Coupled Elastoplastic Damage of Clastic Sandstone of Different Burial Depths

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