Mechanical response of permeability evolution to anisotropic structure of reservoir rock under true triaxial stress path
Mechanical response of permeability evolution to anisotropic structure of reservoir rock under true triaxial stress path
复制标题
真三轴应力路径下储层岩石各向异性结构渗透率演化的力学响应
DOI：
10.1007/s40948-021-00249-2
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发表时间：
2021-08-01
影响因子：
5
通讯作者：
Zhao, Honggang
中科院分区：
文献类型：
--
作者：
Liu, Chao;Song, Zhenlong;Zhao, Honggang
在非常规天然气开发中，真三轴应力场和各向异性结构面对储层岩石的变形和渗透率演化起着重要作用。本研究对具有各自独特结构特征的砂岩、页岩和煤在相同平均主应力（p）和广义剪应力（q）下进行了真三轴实验。结果表明，在弹性范围内，砂岩体应变不受应力路径的影响。而页岩的变形则与页岩层理的变形密切相关。泥页岩的应力路径对其变形行为和渗透率演化有重要影响。有趣的是，砂岩渗透率强烈依赖于固定pandq下的剪切行为，即，它随广义剪应变的增大而增大。剪切作用引起的砂岩颗粒间的摩擦滑动对渗透率的提高起着重要作用。对于页岩，垂直于层面的应力对渗透率演化起着重要作用，其作用强于页岩颗粒间的摩擦滑动效应。煤的渗透性在砂岩和页岩之间演化，这与其独特的割理系统有关。在非常规天然气开采过程中，为避免忽略影响渗透率演化的重要因素，应根据储层岩石的结构特征选择渗透率模型，文章强调颗粒间的摩擦滑动决定了砂岩的渗透率，垂直于层面的应力对页岩的渗透率起着重要作用，煤的渗透率与其独特的割理系统有关。
In unconventional natural gas development, the true triaxial stress field and anisotropic structure plane play an important role in the deformation and permeability evolution of reservoir rocks. In this research, the true triaxial experiments of sandstone, shale and coal with their own unique structural characteristics under the identical mean principal stress (p) and generalized shear stress (q) are performed. The results show that the volumetric strain of sandstone is not affected by the stress path within the elastic range. However, that of shale is closely related to the deformation of shale bedding. The stress path of shale has a significant impact on its deformation behavior and permeability evolution. Interestingly, the sandstone permeability is strongly dependent on the shear behavior under fixedpandq, i.e., it increases with the increasing generalized shear strain. The frictional sliding between sandstone particles induced by shear effect plays an important role in promoting the permeability. For shales, the stress normal to bedding planes plays an important role in permeability evolution, which is stronger than the frictional sliding effect between shale particles. The permeability of coal evolves between sandstones and shales, which is related to its unique cleat system. To avoid neglecting the important factors affecting permeability evolution in unconventional natural gas extraction, the permeability model should be selected according to the structural characteristics of reservoir rocks.Article highlightsFrictional sliding between particles determines the sandstone permeability.Stress normal to bedding planes plays an important role in shale permeability.The permeability of coal is related to its unique cleat system.