陆相咸化湖盆“低TOC”烃源岩高生烃效率探讨——以苏北盆地溱潼凹陷阜宁组二段泥页岩为例  

Discussion on high hydrocarbon generation efficiency of saline lacustrine source rocks with low TOC:A case study of the second member of Funing Formation,Qintong Sag,Subei Basin

作　　者：高玉巧[1] 何希鹏[1] 程熊 唐玄[2] 花彩霞[1] 昝灵[1] 张培先[1] 陈学武 庞伊伟 GAO Yuqiao;HE Xipeng;CHENG Xiong;TANG Xuan;HUA Caixia;ZAN Ling;ZHANG Peixian;CHEN Xuewu;PANG Yiwei(Sinopec East China Oil&Gas Company,Nanjing,Jiangsu 210000,China;School of Energy Resource,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国石化华东油气分公司,江苏南京210000 [2]中国地质大学(北京)能源学院,北京100083

出　　处：《油气藏评价与开发》2024年第5期678-687,共10页Petroleum Reservoir Evaluation and Development

基　　金：中国石化科技项目“溱潼凹陷低TOC陆相页岩油勘探开发关键技术”(P23190);国家自然科学基金青年科学基金项目“火山活动的分子地球化学响应与有机质富集机制——以上寺剖面大隆组为例”(42302189);国家自然科学基金面上项目“超临界CO_(2)与陆相干酪根-油-水体系的相互作用机理研究”(42372164)。

摘　　要：苏北盆地溱潼凹陷阜宁组二段(以下简称阜二段)页岩油勘探取得重大突破,但其泥页岩总有机碳含量(TOC)普遍不高,一般低于2%。业界认为陆相咸化湖盆“低TOC”烃源岩能生成大量油气,称之为陆相咸化湖盆的“低TOC”高效生烃模式。由于生排烃效应,烃源岩的TOC会降低,因此,恢复烃源岩原始TOC对客观认识烃源岩的生烃能力、油气资源评价和持续增储上产具有重要意义。以溱潼凹陷典型钻井阜二段泥页岩为研究对象,利用生烃模拟实验和岩石热解资料,采用热模拟TOC演化、有效碳(PC)演化和元素质量守恒法,对QY1井阜二段泥页岩TOC进行了恢复。结果表明:咸化湖盆烃源岩的TOC恢复系数最高可达3~4,且受到岩相的重要影响。随着热演化程度增高,TOC恢复系数增大,纹层状页岩TOC恢复系数高于块状泥岩,QY1井阜二段Ⅳ亚段泥岩、Ⅰ—Ⅲ亚段页岩TOC恢复系数可分别高达1.1~1.5、1.5~3.0。母质类型和生烃活化能的差异导致页岩成烃转化率和TOC恢复系数高于泥岩。Significant progress has been made in shale oil exploration within the second member of the Funing Formation in the Qintong Sag,Subei Basin.However,geologists have noted that the measured Total Organic Carbon(TOC)contents are generally below 2%.Despite this,it is believed that source rocks in saline lacustrine basins can generate substantial amounts of petroleum even with low organic matter abundance,a concept known as the“low TOC”and highly efficient hydrocarbon generation mode of saline lacustrine source rocks.As hydrocarbon generation and expulsion occur during thermal maturation,the TOC levels in source rocks decrease.Therefore,accurately restoring the original TOC of these source rocks is crucial for a proper understanding of their hydrocarbon generation capacity,as well as for evaluating petroleum resources and supporting reserve growth and production enhancement.This study focuses on the typical mudstones and shales of the second member of the Funing Formation in the Qintong Sag.Techniques such as hydrocarbon generation simulation experiments,rock pyrolysis data,TOC and productive carbon content evolution during thermal simulation,and an element mass conservation method were employed to restore the original TOC of these mudstones and shales.The findings reveal that the TOC recovery coefficient of these saline source rocks can exceed values between 3 to 4,and this coefficient is significantly influenced by the lithology.The study found that:the TOC recovery coefficient increases with thermal maturity,the coefficient for laminated shale is higher than that for massive mudstone,and the TOC recovery coefficients for mudstones in theⅣsub-member and shales in theⅠtoⅢsub-members of the second member of the Funing Formation range from 1.1~1.5 and 1.5~3.0,respectively.These variations are attributed to differences in the type of organic matter and the hydrocarbon generating activation energy,leading to a higher hydrocarbon transformation rate and TOC recovery coefficient in shales compared to mudstones.

关 键 词：低有机质丰度 烃源岩 总有机碳 恢复系数 阜宁组二段 

分 类 号：TE357[石油与天然气工程—油气田开发工程]