双组份岩石压缩系数推导与试验验证

Compressibility derivation and experimental verification of two-component rock

岩石压缩系数一直是油藏工作者研究的热点问题,近年来黏土矿物的特殊性质对岩石压缩系数的影响已成为人们关注的重点。将岩石视为"骨架+黏土"的双组份模型,从岩石压缩系数定义出发,运用弹性力学理论,推导出双组份岩石压缩系数公式,得到岩石压缩系数与黏土含量及黏土力学性质的理论关系。以大牛地气田含黏土砂岩为对象,通过岩石变内压三轴压缩试验实测岩石压缩系数,并同时进行岩石的微观试验研究。计算出双组份压缩系数公式及其他几种不考虑黏土的传统压缩系数求解方法对应的岩石压缩系理论值,将理论值与岩石压缩系数实测值进行对比分析,结果发现,双组份岩石压缩系数理论值与实测结果更接近,说明了考虑黏土影响的双组份岩石压缩系数理论的合理性,该理论为油气储层岩石压缩系数的预测开拓了新的思路。

The rock compressibility has always been the focus of reservoir workers; and the influence of clay characteristics on the rock compressibility gets more attention in recent years. Rock is regarded as two-component model ＇clay ＋ matrix＇, based on definition of rock compressibility and theories of elastic mechanics, two-component rock compressibility formula is derived; thus the theoretical relationship between the rock compressibility and content of clay as well as the mechanical properties of clay has been found. Clay-containing sandstone cores from Daniudi gas field are regarded as the research objects, the compressibilities of these cores are measured by triaxial compression experiment with variable internal pressures, the micro-experimental study is carried out simultaneously. Theoretical values of compressibility of these cores are obtained by using the two-component rock compressibility formula as well as the other traditional mathematical methods which do not take clay into consideration. By comparison among the theoretical values of compressibility of different mathematical methods and the measured ones, two-component rock compressibility is proved the closest to the experimental result, which indicates the rationality of theory of two-component rock compressibility, this theory develops a new ideal for predicting the reservoir compressibility.