Study on the influence of elastic modulus heterogeneity on in-situ stress and its damage to gas shale reservoirs
Study on the influence of elastic modulus heterogeneity on in-situ stress and its damage to gas shale reservoirs
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弹性模量非均质性对地应力的影响及其对含气页岩储层的伤害研究
DOI：
10.1016/j.jnggs.2018.08.002
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发表时间：
2018-06
影响因子：
--
通讯作者：
Liu Lu
中科院分区：
文献类型：
--
作者：
Wang Daobing;Ge Hongkui;Yu Bo;Wen Dongsheng;Zhou Jun;Han Dongxu;Liu Lu
页岩非均质性对钻井完井、水力压裂以及油气开发动态有重要影响。然而，它缺乏对水力压裂过程中的力学非均质性和“应力阴影”效应所造成的岩石损伤/破坏的描述。本文采用Galerkin有限元方法，基于COMSOL多物理软件中的求解器和MatLab脚本开发，对流体-机械耦合相互作用进行了数值模拟。用威布尔概率密度函数表示气页岩的力学非均质性。在水力压裂全流固耦合条件下，数值模拟了气页岩压裂过程中力学非均质性对等效应力、应变能密度、损伤因子和流体压力的影响。在完全均匀的地层中，沿某条直线的von-Mose应力、应变能密度和损伤因子曲线呈现出明显的递减分布。随着地层的非均质性增强，其分布曲线呈现波动。此外，von-Mise应力和应变能密度与损伤因子有很好的相关性。在此基础上，提出了二维平面应变条件下岩石损伤断裂和力学非均质引起的“应力阴影”效应的计算方法。即用单点或单线上的von-Mise应力或应变能密度来表征局部破裂的程度或应力的影子效应，用单位面积上的平均应变能密度来表征岩石的破裂程度或影子效应的强度。该研究对进一步完善SRV压裂设计，提高页岩气井产能具有重要意义。
Shale heterogeneity has a significant effect on drilling and completions, hydraulic fracturing, as well as hydrocarbon development performance. However, it lacks representation of rock damage/failure caused by the mechanical heterogeneity and “stress shadow” effect during the hydraulic fracturing process. In this paper, the Galerkin finite element method was adopted to numerically simulate the hydro-mechanical coupled interaction based on the solver in the COMSOL Multiphysics software and Matlab scripting development. The Weibull probability density function was used to represent the mechanical heterogeneity of gas shale. Under the condition of fully fluid-solid coupling during the fracking process, the effect of mechanical heterogeneity on von – Mises stress, strain energy density, damage factor, and fluid pressure was numerically simulated in the gas shale wells. The curves of von – Mises stress, strain energy density, and damage factor along a certain straight line showed the obvious decreasing distribution in a completely homogeneous formation. As the strata are heterogeneously enhanced, their distribution curves showed fluctuations. Moreover, von – Mises stress and strain energy density had a good relationship with damage factors. Accordingly, the method of rock damage/fracture and "stress shadow" effect caused by mechanic heterogeneity was put forward under the circumstance of two–dimensional plane strain. That was to use, the von – Mises stress or strain energy density at the single point or line to characterize the degree of local rupture or the shadow effect of stress, and the average strain energy density per unit area to characterize the degree of rupture of the rock or the intensity of the shadow effect. The study is of great significance to further improve the SRV(Stimulated Reservoir Volume) fracturing design and the productivity of gas shale wells.
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影响因子：
5.3
作者：
J. Pogacnik;D. Elsworth;M. O'Sullivan;J. O'Sullivan
通讯作者：
J. Pogacnik;D. Elsworth;M. O'Sullivan;J. O'Sullivan
影响因子：
6.2
作者：
Wancheng Zhu;Chun’an Tang
通讯作者：
Wancheng Zhu;Chun’an Tang
影响因子：
6.7
作者：
Jiehao Wang;D. Elsworth;Wancheng Zhu;Jishan Liu;Yuehua Wu
通讯作者：
Jiehao Wang;D. Elsworth;Wancheng Zhu;Jishan Liu;Yuehua Wu
影响因子：
1.5
作者：
Zhu Wancheng;Wei Chenhui;Tian Jun;Yan Tianhong;Tang Chun-an
通讯作者：
Zhu Wancheng;Wei Chenhui;Tian Jun;Yan Tianhong;Tang Chun-an
影响因子：
--
作者：
Junjing Zhang;D. Zhu;A. Hill
通讯作者：
Junjing Zhang;D. Zhu;A. Hill