鄂尔多斯盆地定边—安塞地区延长组下组合储层特征

根据普通薄片、铸体薄片、扫描电镜和岩心分析等资料,对定边—安塞地区（包括定边、吴起、志丹、安塞4个地区）储层岩石学特征、物性特征及影响因素进行了分析.结果表明：吴起与安塞地区为单物源沉积,岩石类型主要为长石砂岩,定边与志丹地区为多物源沉积,岩石类型多样,主要为长石砂岩和岩屑长石砂岩;储层以原生粒间孔和次生溶孔为主,具有低—特低孔隙度和低—超低渗透率特征;受沉积微相和成岩作用的影响,在平面上吴起与定边地区物性最好,志丹地区物性次之,安塞地区物性较差,纵向上长10物性最好,长9物性次之,长7和长8物性均较差.

Characteristics of lower assemblage reservoir of Yanchang Formation in Dingbian-Ansai area,Ordos Basin

Based on the data of thin sections, casting thin sections, scanning electron microscope and core analysis, this paper studied the petrology characteristics, physical properties and influencing factors of lower assemblage reservoir of Yanchang Formation in Dingbian-Ansai area. The result shows that Wuqi and Ansai area are mainly feldspathic sandstone because the sediment source is single, and the sandstone rock types in Dingbian and Zhidan area diversified by different source rocks and are mainly arkose and lithic arkose. The reservoir space of lower assemblage reservoir of Yanchang Formation mainly includes primary intergranular pores and secondary dissolved pores. The reservoir is characterized by low-ultra-low porosity and low-ultra-low permeability. The reservoir properties are affected by sedimentary microfacies and diagenesis. The reservoir properties in Wuqi and Dingbian area are best, the next is in Zhidan area, and the reservoir properties in Ansai area are poor. In longitudinal, the reservoir properties of Chang 10 are the best, the next is Chang 9, and the reservoir properties of Chang 8 and Chang 7 are poor.