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在油气勘探实践中逐渐认识到,仅仅研究盖层当前封闭性能是不够的,还要研究盖层在地质历史中的演化特征及应力状态与脆性–延性匹配关系,从而为盖层封闭的有效性做出评价。以鄂西–渝东地区的不同地质历史及成岩演化程度的泥质岩盖层为研究对象,采用厚壁钢制容器对试样的径向进行约束来模拟单轴应变试验,根据厚壁圆筒理论建立侧向压力和竖向压力之间的关系,获得其前期名义固结压力;并在此基础上,研究前期名义固结压力与单轴抗压强度、声波波速、孔隙率以及黏土矿物含量等因素的关系以及侧压系数的变化规律;初步探讨泥质岩脆性–延性转化特征及相应封闭临界条件,并对几类泥质岩在各种地质条件下封闭能力给出评级。研究对评价不同演化程度泥质岩盖层的封闭性具有重要的指导意义,为下一步建立盖层动–静封闭评价模型奠定基础。
In the exploration of oil and gas, it is gradually realized that it is not enough to study the current sealing performance of the caprock, but also to study the evolution characteristics and the state of stress and brittleness-ductility matching of the caprock in geological history, Make a comment Taking the mudstone caprock of different geological history and diagenetic evolution in West Hubei and East China as the research object, the uniaxial strain test was simulated using the thick-walled steel container constraining the radial direction of the specimen, The relationship between lateral pressure and vertical pressure was established and the nominal consolidation pressure was obtained. On the basis of this study, the relationship between nominal consolidation pressure and uniaxial compressive strength, sonic wave velocity, porosity and clay minerals Content and other factors as well as the variation rule of lateral pressure coefficient. The characteristics of brittle-ductile transformation of shale rock and the corresponding closed critical conditions are discussed preliminarily. The grading ability of several types of mudstone under various geological conditions is also given. The study is of great significance to evaluate the sealing of mudstone caprocks with different evolutionary degrees and lays the foundation for the next step to establish a dynamic-static closure evaluation model of caprock.