再谈岩石的压缩系数 ——回应毛小龙博士

Re-discussion on the rock compressibility: reply to Dr. MAO Xiaolong

李传亮 朱苏阳

西南石油大学石油与天然气工程学院，四川 成都 610599

Petroleum Engineering School, Southwest Petroleum University, Chengdu 610599, China

岩石有9个压缩系数，岩石压缩系数的概念很容易混淆。在油气藏工程应用中，只使用孔隙体积对孔隙压力的压缩系数，也就是通常所说的岩石压缩系数。由于常规方法测量的岩石压缩系数偏高，而且出现了逻辑反转现象，即高孔隙度的岩石具有较低的压缩系数，这给油藏工程应用带来了负面影响。为了理清岩石压缩系数的相关问题，根据岩石力学的基础理论，对岩石压缩系数进行了分析。结果表明：岩石的孔隙压缩系数只有在孔隙度小于0.5时，才小于骨架压缩系数，其他情况下都大于骨架压缩系数；岩石压缩系数偏高的测量结果是表皮效应所致，并非是骨架颗粒的重排和滑动；岩石压缩系数不能用有效应力进行定义，必须用真实应力进行定义；孔隙压缩系数与孔隙度并非呈负相关，而是呈正相关，即高孔隙度的岩石，压缩系数也较高。

There are 9 coefficients of compressibility in rocks, and the concept of rock compressibility coefficient is easily confused. In reservoir engineering applications, only the compressibility coefficient of pore volume to pore pressure is used, which is commonly referred to as the rock compressibility coefficient. Because the rock compressibility coefficient measured by the conventional method is high and the logic inversion phenomenon appears, that is, the rock with high porosity has a lower compressibility coefficient, which has a negative impact on reservoir engineering application. In order to clarify the problems related to the rock compressibility coefficient, the rock compressibility coefficient was analyzed according to the basic theory of rock mechanics, and the following understanding is obtained. The pore compressibility coefficient of rocks is lower than the skeleton compressibility coefficient only when the porosity is lower than 0.5, and is larger than the skeleton’s in other cases. The measurements of high rock compressibility coefficient are caused by the skin effect, not the rearrangement and sliding of skeleton particles. The rock compressibility coefficient cannot be defined by effective stress, but must be defined by real stress. The rock compressibility coefficient is not negatively correlated with porosity, but positively, that is, the rock with high porosity has a higher compressibility coefficient.

10.6056/dkyqt202004012