鄂尔多斯盆地北部成岩作用对储集性的影响

Influence of diagenesis on reservoir properties in northern Ordos Basin

通过大量常规薄片及铸体薄片的分析鉴定,结合扫描电镜、阴极发光和黏土矿物X射线衍射分析,对鄂尔多斯盆地北部盒8段储层的成岩作用及影响进行了研究。结果表明:受成岩物质和成岩能量两大因素影响,盆地北部东区和西区孔隙类型有一定差异,西区以粒间溶孔和岩屑溶孔为主,东区则以岩屑溶孔和晶间孔为主;研究区储集层可划分为4种成岩相类型,其中硅质胶结+钙质强溶蚀相是最有利的成岩相类型;成岩作用最终影响储集性能,主要表现为胶结作用导致储层致密,溶蚀作用改善储层储集性。深入研究储层成岩作用可为优选天然气相对富集区,促进盆地北部气藏的有效勘探开发提供理论依据。

Based on analysis of conventional thin section, casting thin section, scanning electron microscope, cathodelu- minescence and X-ray, this paper studied the reservoir diagenesis and its influence on reservoir properties of He 8 member in northern Ordos Basin. The result shows that because of the influence of diagenetic material and energy, pore types in the western zone are different from the pore types in the eastern zone of northern Ordos Basin. There are mainly intergranular dissolved pores and lithic dissolved pores in the western zone, whereas lithic dissolved pores and intercrystalline pores in the eastern zone. Besides, diagenetic facies can be divided into four types, among which the combination of siliceous cement phase and calcium dissolved phase is the favorable one. Reservoir properties are influenced by diagenesis, which displays that the cementation tighten reservoir and dissolution improved reservoir properties. Further research on reservoir diagenesis can provide theoretical foundation for the optimization of abundant gas accumulation zone and promotion of gas reservoir exploration and production in the northern Ordos Basin.