元坝地区须二下亚段砂岩储层致密化与天然气充注关系

The relationship between densification of sandstone reservoir and natural gas charging in the lower part of the second member of Xujiahe Formation in Yuanba area

白国帅,蒋有录,赵承锦,刘明,王宇

中国石油大学（华东）地球科学与技术学院，山东 青岛 266580 中国石化勘探分公司勘探研究院，四川 成都 610041

School of Geosciences, China University of Petroleum, Qingdao 266580, China Exploration Research Institute of SINOPEC Exploration Company, Chengdu 610041, China

文中基于铸体薄片、阴极发光、扫描电镜及流体包裹体等分析测试方法，对元坝地区须二下亚段储层特征、致密化过程、天然气充注时间与期次等进行研究，探讨了绿泥石衬里岩屑砂岩和强压实岩屑砂岩2种砂岩储层致密化与天然气充注的时间匹配关系。研究结果表明：须二下亚段储层属于致密砂岩储层，储集空间以残余粒间孔为主，压实作用是储层致密化的主要原因；绿泥石衬里岩屑砂岩由于绿泥石膜的保孔作用，储层致密化时间相比强压实岩屑砂岩较晚；结合天然气充注史与储层致密史，绿泥石衬里岩屑砂岩具有边致密边成藏的特征，强压实岩屑砂岩具有先致密后成藏的特征。该研究对明确该地区天然气成藏机理及富集规律具有重要意义。

Based on the analysis and test methods of cast thin section, cathode luminescence, scanning electron microscope and fluid inclusions, this paper studies the reservoir characteristics, densification process and natural gas charging period of the lower part of the second member of Xujiahe Formation in Yuanba area. On this basis, the time matching relationship between reservoir densification and natural gas charging of chlorite-lined lithic sandstone and strongly compacted lithic sandstone is discussed. The results show that the reservoirs of the lower part of the second member of Xujiahe Formation are tight sandstone reservoirs. The reservoir space is dominated by residual intergranular pores, and compaction is the main reason for the densification of the reservoir. Due to the pore preservation effect of chlorite film on chlorite-lined lithic sandstone, the reservoir densification time is later than that of strongly compacted lithic sandstone. Combining with the history of natural gas charging and reservoir densification, the chlorite-lined lithic sandstone has the characteristics of densification and accumulation at the same time, and the strongly compacted lithic sandstone has the characteristics of first densification and later hydrocarbon accumulation. This study is of great significance to clarify the reservoir forming mechanism and enrichment law of natural gas in this area.

10.6056/dkyqt202201004