考虑颗粒变形和颗粒间变形的孔隙压缩系数

Pore compression coefficient considering granular deformation and inter-granular deformation

目前,油藏工程研究对岩石基础物性参数孔隙压缩系数争议颇多,其根本问题是对岩石的表观体积、基质颗粒体积、孔隙体积的应力应变机理尚不清楚。文中在对Terzaghi和Skempton 2个经典有效应力原理深入分析基础上,综合考虑颗粒变形和颗粒间变形,采用2种方法系统地推导了多孔介质的3个体积随流体压力变化的关系,建立了精确计算孔隙压缩系数的新关系式,并进行了规律分析与实例验证。研究表明:孔隙体积变化与颗粒变形、颗粒间变形同时相关,且多数岩石颗粒间变形远大于颗粒变形;孔隙压缩系数远大于表观体积压缩系数,表观体积压缩系数又大于颗粒压缩系数;"高孔高压缩"逻辑规律适用于表观体积压缩系数,而孔隙压缩系数由于孔隙体积自身是分母,与孔隙度负相关;孔隙压缩系数新关系式与实验测试结果和Hall图版反映的规律一致。

At present, there are many controversies about the study of pore compression coefficient, the basic physical parameter of rock in reservoir engineering research. The essential issue of these arguments is that the stress-strain relationship among total volume, particle volume, and pore volume of porous medium is not clear, which needs to be clarified. Based on deep analysis of the classical effective stress principles of Terzaghi and Skempton, the relationship between three types of volumes of porous media and the fluid pressure change was systematically deduced by two methods considering both granular deformation and inter-granular deformation, a new relation formula of pore compression coefficient was established, and regular analysis and case verification was carried out. The results indicate that pore volume deformation is related to both granular deformation and inter-granular deformation,and inter-granular deformation of most rocks is much larger than granular deformation; pore compression coefficient is much larger than total volume compression coefficient, which is larger than particle volume compression coefficient; the ＂high compression with high porosity＂ logic applies to total volume compression coefficient, while porosity compression coefficient is negatively correlated with porosity since pore volume itself is the denominator; the new relational formula is consistent with experimental test results and Hall curve chart.