砂岩试验和理论研究

大孔隙率砂岩具有特殊的力学特性,对其力学行为进行试验和理论研究不仅具有理论意义,而且具有工程实践作用。对大孔隙率砂岩在不同饱和液体情况下的力学特性进行了试验研究,以2种理论对其破坏特征进行了解释,紧接着推广了帽盖模型,并对试验结果进行了模拟。试验结果证明了大孔隙率砂岩存在一临界围压,随着围压增加,砂岩由以压剪破坏为主逐渐转化为以孔隙坍塌破坏为主;在油水转化过程中,也存在一临界饱和度,超过此临界饱和度,其力学特性发生较大的改变。该试验和理论研究能合理地解释注水采油引起的地表沉降。

LABORATORY AND THEORETICAL RESEARCHES ON SANDSTONE

The mechanical behaviors of sandstone with large porosity are different from the other rocks;the research of its mechanical properties is very important not only in the theory but also in the practice. The two sorts failure theories are used to explain the failure types of sandstone with large porosity based on the laboratory research under different saturated liquid conditions;then the conventional Cap Model is extended and is used to simulate the testing results. A critical value of confining pressure is proved to exist during the process from mainly pressure-shear failure to mainly slough failure. When the confining pressure is increased , the mainly pressure-shear failure can be changed into slough failure. A critical saturated degree also exists during the change processes from oil saturation to water saturation. When water saturated degree is above critical value,the mechanical features of sandstone with large porosity are changed clearly. The theoretical and testing results explain reasonably the subsidence from oil exploiting by water injection.