鄂尔多斯盆地临兴区块盒8段致密砂岩物性影响因素

通过分析铸体薄片、物性、扫描电镜及压汞等资料，探讨了鄂尔多斯盆地东北缘临兴区块盒8段致密砂岩的储层特征及物性影响因素。结果表明：盒8段储层岩性以岩屑砂岩和长石岩屑砂岩为主，平均孔隙度为7.1%，平均渗透率为0.38 mD；主要孔隙类型为次生溶孔，孔喉半径的分布以双峰状为主，主峰值偏向于相对小的半径，砂岩以相对小孔隙为主；成岩作用主要包括压实作用、溶蚀作用、胶结作用及交代作用等，具有压实强而普遍、溶蚀普遍但不充分、胶结和交代作用强等特征；受贫石英、富岩屑和长石的碎屑组分特征影响，各组分含量对物性有影响但无明显控制作用；粒度是物性的主控因素，粒度越粗物性越好；此外，溶蚀作用对砂岩物性也有一定的积极作用，而封闭成岩体系下的强胶结作用是导致储层致密的主要因素。

Influencing factors of the physical properties of tight sandstone in He 8 Member of Linxing Block, Ordos Basin

Based on the analysis of cast thin sections, physical properties, scanning electron microsscopy and mercury injection data, the reservoir characteristics and the fluencing factors of physical properties of tight sandstone in the He 8 Member of Linxing Block, northeastern margin of Ordos Basin were discussed. The results show that the reservoir lithology of the He 8 Member is mainly lithic sandstone and feldspar lithic sandstone, with an average porosity of 7.1% and an average permeability of 0.38 mD. The main pore type is secondary solution pore, and the distribution of pore throat radius is bipeak-like, and the main peak value tends to be relatively small radius. Sandstone is mainly dominated by relatively small pores. Diagenesis mainly includes compaction, dissolution, cementation, metasomatism, etc., which has the characteristics of strong and common compaction, common but insufficient dissolution, strong cementation and metasomatism. It is affected by the clastic component characteristics of poor quartz, rich debris and feldspar, and the content of each component has an effect on the physical property but has no significant control effect. Particle size is the main controlling factor of physical properties, the coarser the particle size, the better the physical properties. In addition, dissolution also has a positive effect on the physical properties of sandstone, and the strong cementation under the closed diagenetic system is the main factor leading to the current tightness of the reservoir.