Abstract

The real pores in digital cores were simplified into three abstractive types, including prolate ellipsoids, oblate ellipsoids and spheroids. The three-dimensional spheroidal-pore model of digital core was established based on mesoscopic mechanical theory. The constitutive relationship of different types of pore microstructure deformation was studied with Eshelby equivalent medium theory, and the effects of pore microstructure on pore volume compressibility under elastic deformation conditions of single and multiple pores of a single type and mixed types of pores were investigated. The results showed that the pore volume compressibility coefficient of digital core is closely related with porosity, pore aspect ratio and volumetric proportions of different types of pores. (1) The compressibility coefficient of prolate ellipsoidal pore is positively correlated with the pore aspect ratio, while that of oblate ellipsoidal pore is negatively correlated with the pore aspect ratio. (2) At the same mean value of pore aspect ratio satisfying Gaussian distribution, the more concentrated the range of pore aspect ratio, the higher the compressibility coefficient of both prolate and oblate ellipsoidal pores will be, and the larger the deformation under the same stress condition. (3) The pore compressibility coefficient increases with porosity. (4) At a constant porosity value, the higher the proportion of oblate ellipsoidal and spherical pores in the rock, the more easier for the rock to deform, and the higher the compressibility coefficient of the rock is, while the higher the proportion of prolate ellipsoidal pores in the rock, the more difficult it is for rock to deform, and the lower the compressibility coefficient of the rock is. By calculating pore compressibility coefficient of ten classical digital rock samples, the presented analytical elliptical-pore model based on real pore structure of digital rocks can be applied to calculation of pore volume compressibility coefficient of digital rock sample.

中文翻译：

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通过数字岩石的球形孔隙建模估算孔隙体积可压缩性

摘要

数字核心中的实际孔被简化为三种抽象类型，包括长椭球体，扁长椭球体和椭球体。基于介观力学理论，建立了数字磁心的三维球孔模型。利用Eshelby等效介质理论研究了不同类型孔隙微结构变形的本构关系，研究了单一类型和多种类型孔隙和混合类型孔隙的弹性变形条件下，孔隙微结构对孔隙体积压缩率的影响。结果表明，数字岩心的孔隙体积压缩系数与孔隙率，孔隙纵横比和不同类型孔隙的体积比密切相关。（1）椭圆形长孔的压缩系数与孔的长径比呈正相关，而椭圆形长孔的压缩系数与孔的长径比呈负相关。（2）在满足高斯分布的相同孔隙长宽比平均值下，孔隙长宽比范围越集中，长椭圆形和扁长椭圆形孔的压缩系数越高，并且在相同应力下的变形越大。健康）状况。（3）孔隙压缩系数随孔隙率增加而增加。（4）在恒定孔隙率的情况下，岩石中椭圆形和椭圆形孔的比例越高，岩石越容易变形，并且岩石的压缩系数越高，岩石中椭圆形长孔的比例越高，岩石变形的难度就越大，岩石的压缩系数越低。通过计算十个经典数字岩样的孔隙可压缩系数，提出的基于数字岩实际孔隙结构的解析椭圆孔模型可用于计算数字岩样的孔隙体积可压缩系数。