鄂尔多斯盆地正宁地区盒8段致密砂岩储层特征研究
Study on the Characteristics of Tight Sandstone Reservoirs in He 8 Member of Zhengning Area, Ordos Basin

鄂尔多斯盆地南部正宁地区盒8段河道砂体发育，区域内宁古3井在盒8段获得高产气流，具有较大的勘探潜力。通过薄片鉴定、岩心常规物性分析等手段，对研究区盒8段储层特征进行了详细研究，结果表明：正宁地区盒8段砂岩类型以岩屑石英砂岩和岩屑砂岩为主，含少量石英砂岩，碎屑组分中长石含量较少，多数已完全高岭石化或被方解石交代。岩屑类型以变质岩为主；盒8段砂岩孔隙度主要在4%~10%，平均6.71%。渗透率主要在0.01~1 mD，平均0.36 mD，属特低孔、特低渗储层；盒8段原生孔隙相对不发育，次生溶孔和晶间孔贡献了主要的孔渗。研究区目的层复合型孔隙发育，其中以溶孔 + 晶间孔型组合、溶孔 + 粒间孔型组合较好，具有较大的储集和渗流意义。
The channel sand bodies are well developed in the He 8 Member of Zhengning area of the southern Ordos Basin. The well Ninggu 3 in the area has obtained high-yield gas flow in the He 8 Member, which has great exploration potential. By means of thin section identification and core conventional physical property analysis, the reservoir characteristics of the 8^th member of Shihezi Formation in the study area were studied in detail. The results show that the sandstone types of the He 8 Member in Zhengning area are mainly lithic quartz sandstone and lithic sandstone, with a small amount of quartz sandstone. The content of feldspar in the clastic components is less, and most of them have been completely kaolinized or replaced by calcite. The type of rock debris is mainly metamorphic rock; the porosity of sandstone in He 8 member is mainly 4%~10%, with an average of 6.71%. The permeability is mainly between 0.01~1 mD, with an average of 0.36 mD, which is an ultra-low porosity and ultra-low permeability reservoir. The primary pores are relatively undeveloped in the He 8 Member, and the secondary dissolved pores and intercrystalline pores contribute to the main porosity and permeability. The composite pores of the target layer in the study area are developed, among which the combination of dissolved pores + intercrystalline pores and the combination of dissolved pores + intergranular pores are better, which has great reservoir and seepage significance.