四川盆地宁西地区奥陶系五峰组—志留系龙马溪组页岩气富集主控因素  

Main controlling factors of shale gas enrichment of Ordovician Wufeng Formation-Silurian Longmaxi Formation in Ningxi area,Sichuan Basin

作　　者：杨学锋 赵圣贤 刘勇[1] 刘绍军 夏自强 徐飞 范存辉[2] 李雨桐 YANG Xuefeng;ZHAO Shengxian;LIU Yong;LIU Shaojun;XIA Ziqiang;XU Fei;FAN Cunhui;LI Yutong(Research Institute of Shale Gas,PetroChina Southwest Oil&Gas Field Company,Chengdu 610500,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]中国石油西南油气田公司页岩气研究院,成都610500 [2]西南石油大学地球科学与技术学院,成都610500

出　　处：《岩性油气藏》2024年第5期99-110,共12页Lithologic Reservoirs

基　　金：中国石油西南油气田公司科研项目“双龙—罗场向斜富集条件及有利区研究”(编号:20210304-07)资助。

摘　　要：通过岩心观察、实验测试、地球物理解释及生产动态资料评价,对四川盆地宁西地区奥陶系五峰组—志留系龙马溪组烃源岩和储层特征进行了分析,结合构造-热演化-压力演化史、断层发育特征,探讨了页岩气富集的主控因素。研究结果表明:(1)宁西地区五峰组—龙马溪组一段1亚段(龙一1)发育深水陆棚相富有机质页岩,干酪根类型以Ⅰ型为主,有机质丰度较高,TOC平均值大于3.8%,Ro平均值高于3.0%,处于过成熟阶段;优质烃源岩分布于五峰组—龙一13小层,龙一14小层生烃潜力差。(2)研究区五峰组—龙一1亚段储集层条件优越,脆性指数高,平均值大于55%,自下而上呈下降趋势;储集空间有纳米级无机孔和有机孔、构造成因高角度剪切缝和垂直缝;孔隙度为2.20%~5.30%,平均值为3.84%,龙一11—龙一13小层孔隙度较大。(3)研究区页岩气成藏模式为层内自生自储,受控于源-储配置、构造-热演化、断层级别和裂缝发育程度,源-储配置控基础,脆性矿物含量和孔隙度值越高,TOC值越高;构造-热演化调气藏,晚二叠世(250 Ma)以前地层持续埋藏及峨眉山大火成岩省促进了五峰组—龙马溪组页岩气热解生烃,晚白垩世(66 Ma)至今,构造抬升使气藏发生调整与散失;断层控保存,层内发育的断层有利于页岩气的保存,断层规模越大,越不利于页岩气富集;裂缝系统控产能,向斜中部构造变形弱,断层密度低,裂缝发育程度中等,有利于页岩气的富集,而向斜周缘构造变形强度大,断层密度大,裂缝系统极为发育,不利于页岩气富集。Through core observation,experimental testing,geophysical interpretation and production dynamic data evaluation,the characteristics of source rocks and reservoirs of Ordovician Wufeng Formation-Silurian Longmaxi Formation in Ningxi area of Sichuan Basin were analyzed.Combined with the history of tectonic-thermal evolution-pressure evolution and fault development,the main controlling factors of shale gas enrichment were discussed.The results show that:(1)Organic-rich shale in deep-water shelf facies is developed in Wufeng Formation to the submember of the first member of Longmaxi Formation(Long 11),The kerogen is mainly typeⅠ,with a high organic matter abundance,an average TOC value greater than 3.8%,and an average Ro value greater than 3.0%,indicating that it is in the over mature stage.High-quality source rocks are distributed in Wufeng Formation to the third sublayer of Long 11,whilethe fourth sublayer of Long 11 has poor hydrocarbon generation potential.(2)The reservoir conditions of Wufeng Formation to Long 11 in the study area are superior,with a high brittleness index and an average value greater than 55%,showing a downward trend from bottom to top.The reservoir spaces include nanoscale inorganic and organic pores,as well as high angle shear fractures and vertical fractures caused by structural factors.The porosity ranges from 2.20%to 5.30%,with an average of 3.84%.The porosity of the first to third sublayers of 1 Long1 is relatively high.(3)The accumulation model of shale gas in the study area is“self generation and self reservoir”within the layer,controlled by source-reservoir configuration,tectonic-thermal evolution,fault level,and fracture development degree.The source-reservoir configuration controls the foundation,and the higher the brittle mineral content and porosity value,the higher the TOC value.Continuous burial of strata before Late Permian(250 Ma)and Emeishan Large Igneous Province promoted the pyrolysis and hydrocarbon generation of shale gas of Wufeng-Longmaxi Formation.From the Late Cr

关 键 词：页岩气 深水陆棚相 自生自储 源-储配置 构造-热演化 断层密度 脆性指数 五峰组—龙马溪组 宁西地区 四川盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]