不同坐标系中裂缝渗透率的定量计算

Quantitative calculation of the tectonic fracture permeability in different coordinate systems

将复杂的裂缝性地质体离散成相对简单的单元,分析了单元中裂缝产状与地应力配置关系,推导得到了主应力坐标系下裂缝渗透率的计算公式;根据各单元的裂缝渗透率在整体的笛卡尔坐标系中投影,推导出了整体坐标系中的渗透率计算公式;对比数值模拟建模过程中习惯使用的几种笛卡尔坐标系,优选出其中一种,各轴分别对应优势裂缝的走向、倾向和垂向,在此坐标系下计算得出的沿着各个坐标轴方向的渗透率,不仅可以很好地反映裂缝渗透率的方向性,还可以体现出不同走向的裂缝对渗透率的贡献,使计算得出的裂缝渗透率更具有实际意义。以石港—桥河口地区实际建模为例,给出了坐标系的优选方法,并对几种坐标系之间的关系进行了说明。

Decomposing the complex geologic body to relatively simple units,based on analyzing the allocation relation between fracture occurrence and ground stress,the formulas of fracture permeability in the principal stress coordinate system were obtained by formula deduction,and computational formulas of the fracture permeability in the whole coordinate system were deduced through projecting the fracture permeability in each unit to the whole Cartesian coordinate system.Comparing several Cartesian coordinate systems which were used often in the process of numerical simulation modeling,each axis of the optimal selection coordinate system was demarcated：-dip、-strike、-vertical of the dominant fracture,permeability along each coordinate axis was calculated in this coordinate system not only can reflect the direction of the fracture permeability,but also reflect the effect of the different strike fracture on permeability,then make the calculated fracture permeability more practical significant.One optimal selection method was given and the relationship of several coordinate systems was illustrated by the application to practical modeling of Shigang-Qiaohekou area.