四川盆地中二叠统茅口组一段岩石微相特征及储层成因——以华蓥山二崖剖面为例

Characteristics of rock microfacies and reservoir genesis of the first Member of Middle Permian Maokou Formation in Sichuan Basin: a case study of Erya section of Huaying Mountain

张庄 宋晓波 苏成鹏 李蓉 王东 石国山

中国石化西南油气分公司勘探开发研究院，四川 成都 610041 中国石化西南油气分公司地质中心实验室，四川 成都 610081

Research Institute of Exploration and Development, Southwest Oilfield Company, SINOPEC, Chengdu 610041, China Geological Center Laboratory, Southwest Oilfield Company, SINOPEC, Chengdu 610081, China

近年来，四川盆地中二叠统茅口组一段（简称茅一段）已成为油气勘探的热点。然而，茅一段岩石类型划分较为粗略，沉积环境认识尚不统一。四川盆地中部华蓥山二崖剖面露头十分优质，通过野外剖面观察和室内薄片鉴定，共识别出6类16种岩石类型，并对各岩石微相类型及沉积环境进行了分析。在此基础上，进一步分析了茅一段储层特征，探讨了茅一段优质储层发育与岩石微相之间的耦合关系，并结合前人研究成果和实验测试数据，分析了优质储层成因机制。结果表明：华蓥山二崖剖面茅一段为中缓坡浅水碳酸盐岩沉积环境，生物化石类型丰富，发育相对低能的生屑滩；优质储层主要发育于生屑泥粒灰岩、富有机质生屑泥粒灰岩和纹层状生屑泥粒灰岩中；储层的形成主要与早期海水埋藏阶段差异成岩作用和早成岩期暴露岩溶作用有关，而优质储层的发育则主要受低能生屑滩和早成岩期暴露岩溶作用的联合控制。该认识可为今后四川盆地茅一段的勘探部署提供理论支撑。

In recent years, the first Member of Middle Permian Maokou Formation ( "Mao 1 Member" for short) in Sichuan Basin has attracted considerable attention for oil and gas exploration. However, the classification of rock types of Mao 1 Member is rough and the understanding of sedimentary environment is controversial. The Erya section of Huaying Mountain in middle Sichuan Basin is well outcropped. Sixteen rock types in six categories are defined by field observation and laboratory thin-section identification, and the rock microfacies types and sedimentary environment are analyzed. On this basis, the reservoir characteristics of the Mao 1 Member are further analyzed to discuss the coupling relationship between the development of high-quality reservoirs and rock microfacies, and the genetic mechanism of high-quality reservoirs is analyzed by previous research results and experimental data. The results show that the sedimentary environment of the Mao 1 Member of Erya section in Huaying Mountain is carbonate ramp, with abundant fossil types and relatively low-energy bioclastic beach. The high-quality reservoirs are mainly developed in bioclastic packstone, organic-rich bioclastic packstone and laminated bioclastic packstone. The formation of reservoirs is mainly related to the differential diagenesis in the early seawater burial stage and eogenetic exposed karstification, while the development of high-quality reservoirs is mainly controlled by the combination of low-energy bioclastic beach and eogenetic exposed karstification. This understanding can provide theoretical guidance for the future exploration of the Mao 1 Member in Sichuan Basin.

10.6056/dkyqt202303007