川南地区二叠系龙潭组岩石特征及与油气的关系

The Rock Characteristics of the Permian Longtan Formation in Southern Sichuan and Its Relationship with Gas

摘要: 四川盆地二叠系龙潭组地层是盆地内非常规油气探勘开发的新热点地层之一。对龙潭组地层岩石特征的认识是勘探开发的基础工作，对后续进一步深入研究油气富集规律有着重要指导意义。本文采用宏观与微观相结合的方法，利用偏光显微镜、场发射扫描电镜和岩石有机碳分析(TOC)等手段，对川南地区龙潭组地层岩石的颜色、岩性、矿物组成、结构构造特征和主要分布范围等进行研究，将其划分为泥页岩、粉砂岩、砂岩、菱铁岩和煤岩5大类，灰黑–黑色炭质泥岩、灰–深灰色粉砂质泥岩、灰白色铝土质泥岩、灰色–深灰色(含砾)细砂岩、灰色–深灰色粉砂岩、灰色–深灰色泥质粉砂岩、灰–深灰色粉–细晶菱铁岩和煤层、煤线9种小类。并按照岩性的不同对岩石总有机碳含量进行了统计，结果表明川南地区龙潭组烃源岩TOC含量介于0.20%~81.38%，平均值为12.12%。其中的炭质泥岩TOC含量介于3.46%~34.16%，平均值为12.71%，是龙潭组页岩气勘探开发的最有利岩类。

Abstract: One of the new hotspots in the exploration and development of unconventional oil and gas in the Sichuan Basin is the Permian Longtan Formation. The understanding of the rock characteristics of the Longtan Formation is the basic work of exploration and development, and it has important guiding significance for the further study of the law of oil and gas enrichment in the future. This article adopts the method of combining macro and micro. Using polarized light microscope, field emission scanning electron microscope, and rock organic carbon analysis (TOC), the color, lithology, mineral composition, structural features and main distribution range of the Longtan Formation rocks in southern Sichuan are studied. The research results are divided into five categories: shale, siltstone, sandstone, siderite and coal rock. The nine small types are: gray-black carbonaceous mudstone, gray-dark gray silty mudstone, gray-white bauxite mudstone, gray-dark gray (with gravel) fine sandstone, gray-dark gray siltstone, gray-dark Gray argillaceous siltstone, gray-dark gray powder-fine crystal siderite and coal seams, coal lines. According to the different lithologies, the total organic carbon content of the rocks was counted. The results show that the TOC content of the Longtan Formation source rocks in southern Sichuan is between 0.20% and 81.38%, with an average value of 12.12%. The TOC content of carbonaceous mudstone ranges from 3.46% to 34.16%, with an average value of 12.71%, which is the most favorable rock type for the exploration and development of shale gas in the Longtan Formation.