鄂尔多斯盆地子长地区盒8、山1段储层特征

Reservoir Characteristics of He8 and Shan1 Members in Zichang Area, Ordos Basin

根据薄片、铸体薄片、扫描电镜及化验分析等资料,对子长地区盒8、山1段储层岩石学、孔隙类型与结构以及物性特征进行研究,并分析了影响优质储层形成的主要控制因素。结果表明:该区盒8、山1段砂岩组成为岩屑砂岩、岩屑石英砂岩、石英砂岩;储层孔隙类型以次生溶孔为主,晶间孔和微裂缝发育;孔喉偏小,孔喉分选和连通性较差,孔隙度和渗透率整体偏低,属于低孔、低渗、特低渗致密储层。盒8段储层孔喉结构和物性略优于山1段。储层主要受沉积作用和成岩作用的控制。沉积作用控制了砂体的展布,强烈的压实、压溶作用及胶结作用是造成该区储层低孔、低渗的主要原因,而高岭石晶间孔、溶蚀作用和破裂作用一定程度上改善了储层物性。

Based on thin section, casting thin section, scanning electron microscopy and laboratory analysis, the petrology, pore type, pore structure and physical properties of reservoirs in He8 and Shan1 members in Zichang area were researched, the main controlling factors affecting the formation of high-quality reservoirs were analyzed. The results show that the sandstones of the He8 and Shan1 members are composed of lithic sandstone, lithic quartz sandstone, and quartz sandstone. The pore types of the reservoir are mainly secondary dissolution pores, while intercrystalline pores and micro-fractures were developed. The characteristics of small pore throats, poor pore throat sorting and connectivity, low physical properties indicates that tight reservoirs have low porosity, low permeability and ultra-low permeability. The pore throat structure and physical properties of reservoir of He8 Member are slightly better than those of Shan1 Member. The reservoir is mainly controlled by sedimentation and diagenesis. Sedimentation controls the distribution of sand bodies. Strong compaction, pressure solution and cementation are the main reasons for the low porosity and permeability of the reservoirs in this area, while the development of kaolinite intercrystalline pores, dissolution and fracture effects are the key factors to improve the physical properties of the reservoir.