鄂尔多斯盆地西缘盒8段储层特征及其成因

Characteristics and genesis of He8 reservoirs in western margin of Ordos Basin

苏里格气田为中国特大型气田，近几年随着勘探开发不断地深入，范围向苏里格气田西部及西南部延伸，其构造位置主要处于盆地西缘天环坳陷构造单元。勘探过程中发现，天环坳陷构造单元地质情况复杂、气藏埋深大，主要目的层上古生界石盒子组盒8段储层特征及含气性南北差异较大。运用岩心资料、重矿物、阴极发光、铸体薄片、压汞和扫描电镜等多种测试方法对天环坳陷构造单元盒8段储层特征做深入研究，分析了影响储层储集性能的主要因素。研究表明，天环坳陷南段、北段受控于不同物源供给及沉积环境，储层特征表现出一定的差异性。南部储层受多物源的控制石英含量高，以硅质、高岭石胶结为主，有少量铁白云石胶结，储集空间以粒间孔为主，储层非均质性较强；北部储层岩屑含量高，硅质、伊利石胶结严重，面孔率低，以岩屑溶孔、晶间孔为主，储层物性较差、气水关系复杂，造成南北储层差异的主要因素为物源、沉积环境及成岩作用等。

Sulige Gasfield is an oversized gasfield in China. In recent years, as the exploration and development continue to deepen, the scope of exploration in Sulige area continues to extend to the west and southwest, and its structural location is mainly in the structural units of Tianhuan Depression on the western margin of the basin. During the exploration, it was found that the geology of the tectonic units in the Tianhuan Depression is complex and the gas reservoirs are deep buried. The reservoir characteristics and gas-bearing characteristics of the main target strata, i.e. the He8 Member of the Shihezi Formation of the Paleozoic, are quite different in the north from the south. Using a variety of test methods such as the core data, heavy minerals, cathodoluminescence, cast thin sections, mercury intrusion, and scanning electron microscopy were used to deeply study the characteristics of He8 reservoirs in the structural units of the Tianhua Depression, and analyze the main factors that affect the reservoir＇s performance. The study shows that the southern and northern sections of the Tianhuan Depression are controlled by different provenance and sedimentary environments, and the reservoir characteristics show some differences; under the control of multiple sources, the southern reservoirs have high quartz content and are mainly cemented by siliceous and Kaolinite, with a small amount of iron dolomite cement. The reservoir space is dominated by intergranular pores, with strong heterogeneity. The northern reservoirs have high debris content, with severe siliceous and illite cementation and low pore-to-section area ratio. It is dominated by detritus-dissolved pores and intercrystalline pores. Properties of the reservoirs are poor and gas-water relations are complex. The main factors causing differences between the north and south reservoirs are the provenance, sedimentary environment and diagenesis.