基于应力关系的岩石压缩系数变化分析

Variation Analysis of Rock Compressibility in View of Rock Stress

岩石的压缩性及其大小对油气勘探、油藏工程研究等具有重要影响,常用的确定方法是实验测定。但被测样品经过大量的处理过程,所受应力被多次改变,导致实验结果存在不可靠性。基于地下岩石各应力间的关系式,通过油气生产过程分析,发现并定义了岩石的骨架应力变化系数λ,其大小与岩石骨架及孔隙压力变化量有关,岩石骨架的成分、强度、结构等会影响λ值。结合岩石压缩系数的定义,通过分析与推导得到了用上覆应力σ、孔隙度、孔隙压力p、骨架应力变化系数λ和骨架参数Css五个参变量表示的压缩系数关系式。通过他人实验数据对关系式进行了分析和验证。结果表明,岩石的孔隙体积、骨架体积、骨架应力、孔隙度、压缩系数(Cp、Cs、Cb)等均受骨架应力变化系数λ的影响。

According to the relationships of overburden pressure, pore pressure, framework stress and porosity, a factor λ is detected and defined after the analysis on oil and gas production. The value of the factor λ is affected by the framework and pore pressure variation. Combining the definition of compressibility coefficient, some compressibility coefficient equations have been received. Data analysis and verification are done using others＇ experimental data. The results show that the pore volume, framework volume, framework stress, porosity, and compressibility coefficient have relations with the factor λ.