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富有机质泥页岩蕴含丰富的油气资源,但成岩研究基础薄弱,已成为制约页岩油气勘探开发进程的重要因素。通过开展成岩热模拟实验,结合扫描电镜观察、流体成分测试及有机酸测试等实验测试手段,全面描述实验过程中所发生的水—岩化学反应,试图揭示泥页岩成岩过程及成岩演化规律。研究结果显示,有机质热演化过程中存在一个较宽的有机酸生成窗口,对孔隙流体性质具有重要影响;长石和方解石存在接力溶蚀现象,长石溶蚀高峰过后紧接着出现方解石溶蚀高峰,但方解石溶蚀窗较窄,此后出现方解石重新沉淀结晶;黏土矿物转化及长石的溶蚀过程中会产生大量自生微晶石英,成链状或簇状胶结泥页岩骨架。泥页岩地层作为一个相对封闭体系,各类成岩作用之间相互关联,相互影响,构成错综复杂的成岩体系,进一步增加其成岩作用研究难度。
Organic-rich shale contains abundant oil and gas resources, but the weak foundation of diagenesis has become an important factor restricting the process of shale oil and gas exploration and development. Through carrying out diagenetic thermal simulation experiment, combined with the scanning electron microscope observation, fluid composition test and organic acid test and other experimental measures, a comprehensive description of the water-rock chemical reaction occurred during the experiment is carried out to reveal the diagenesis and diagenetic evolution of shale. The results show that there is a wide window of organic acid generation during the thermal evolution of organic matter, which has an important influence on the properties of pore fluid. There is a phenomenon of relay dissolution of feldspar and calcite, followed by the peak of dissolution of calcite followed by the dissolution of calcite The window is narrower, and then the calcite re-precipitates and crystallizes. When the clay mineral is transformed and the dissolution of feldspar occurs, a large amount of self-generated microcrystalline quartz is formed into a chain-like or tufted cement shale skeleton. As a relatively closed system, the mud shale strata interrelate and influence each kind of diagenesis and form a complex diagenetic system, which further increases the research difficulty of diagenesis.