鄂尔多斯盆地超低渗透储层形成的宏观地质因素分析

 鄂尔多斯盆地由于特殊的构造特征和沉积背景形成了大面积的低渗透储层。根据扫描电镜、铸体薄片、岩心观察、物性分析、岩心分析化验等资料总结分析了鄂尔多斯盆地X油田长6₃超低渗透储层的微观特征,分析得出超低渗透储层主要受沉积和成岩作用影响。研究区岩性偏细,以细砂岩为主;填隙物含量高;储集空间主要以剩余原生粒间孔与溶蚀孔隙为主。从物性角度来看,储层主要属于低孔、特低孔、超低孔-超低渗储层,以小孔细喉型为主。储层微观特征主要受宏观地质因素控制。沉积作用控制着储层的岩性和填隙物的含量,决定着原生孔隙的大小。成岩作用的压实作用与胶结作用破坏了原生孔隙,溶蚀作用提供了大比例的次生孔隙,改善了研究区的储集空间。

Macro Geology Factor Analysis of Ultra Low Permeability Reservoir Formation in Ordos Basin

Due to the special structures and the depositional setting of Ordos Basin, a large scale low-permeability reservoir is formed there. Based on the studies of scanning electron microscope, casting sheet image, core observation, physical property analysis and core analysis testing, the microscopic features of the ultra low permeability reservoir in Ordos Basin X area Chang6₃ are analyzed . It is shown that the ultra low permeability reservoir is controlled by deposition and diagenesis. The area has few slender rock, and is mainly covered with sandstone, and high interstitial materials. Remaining primary intergranular pores and dissolution pores serve chiefly as the storage space. As far as its physical properties are concerned, the reservoir belongs to a low porosity-extra low porosity-ultra low porosity-ultra permeability reservoir; the reservoir is mainly in the fine pore narrow throat mode. The reservoir microscopic features are controlled by macro geological factors. The deposition decides the reservoir's lithology, interstitial content and sizes of primary pores. The compaction and the cementation of diagenesis destroy primary pores, but the denudation provides a wide range of secondary pores, which improve the storage space of the research area.