深层碳酸盐岩储层溶洞围岩应力分布研究

摘要

The Ordovician carbonate oil pool in northern Renqiu of the Jizhong depression is taken as an example in this article.The rock mechanical parameters in the study area were calculated based on the log data of the oil field,and the typical isolated water long elliptic karst cave of the target reservoir was selected,with its surrounding rock stress and its damage zone calculated by numerical simulation and third strength theory.The results show that:1) Under the combined action of overburden pressure and lateral pressure,the stress concentration effect zone of the long elliptic karst cave surrounding rock is 9 times of the radius.2) The surrounding rock stress of long elliptic karst cave is mainly compressive stress,mainly concentrating in the top and the bottom.3) The filling property of karst cave has great influence on the principal stress difference and damage range of surrounding rock.For the long-elliptic karst cave,the principal stress difference and shear damage of the surrounding rock increase with the increase of filling pressure when the filling pressure is less than 0.1 MPa;while the principal stress difference and the shear damage range of the surrounding rock gradually decrease with the increase of filling pressure when the filling pressure is more than 0.1 MPa.%以冀中凹陷任北奥陶系碳酸盐岩储层为例,基于油田测井资料及岩石力学实验确定了研究区岩石力学参数,对目标储层典型的长椭圆形孤立落水溶洞围岩应力进行了数值模拟,并根据第三强度理论研究了围岩破坏情况.研究结果表明,(1)溶洞在上覆岩层压力和侧向压力的共同作用下,长椭圆形溶洞围岩的应力集中效应带为9倍的半径范围;(2)长椭圆形溶洞围岩应力以压应力为主,主要集中分布在洞顶和洞底;(3)溶洞填充性对其围岩主应力差及破坏范围影响很大.当填充压力小于0.1 MPa时,溶洞围岩主应力差及破坏区域范围随填充压力的增大而增大;而当填充压力大于0.1 MPa时,溶洞围岩主应力差及破坏区域范围随填充压力的增大均呈减小的趋势.