摘要
渝东南地区五峰组—龙马溪组页岩气储层中发育粉砂岩夹层和裂缝脉体。以酉参2井五峰组—龙马溪组页岩有机地球化学特征分析以及粉砂岩夹层和裂缝脉体的显微岩相学、流体包裹体特征分析为基础,结合恢复的酉参2井埋藏生烃史,深入探讨了研究区页岩气的形成与成藏特征。五峰组—龙马溪组页岩的粉砂岩夹层中记录了两期油气充注过程:第一期油气充注时间为早三叠世,页岩为低成熟—成熟阶段,油气的成熟度较低,为粉砂岩夹层石英颗粒中的重质油包裹体以及粉砂岩夹层粒间孔隙中的褐色、深褐色沥青;第二期油气充注时间为早侏罗世,页岩处在成熟阶段,主要为沿切穿石英颗粒微裂缝成带状分布的气烃包裹体以及石英颗粒中充注的轻质油。五峰组—龙马溪组裂缝脉体中捕获大量纯气包裹体,主要成分为CH 4,来源于五峰组—龙马溪组的页岩气,被捕获时间主要为白垩纪。渝东南局部地区五峰组—龙马溪组页岩虽具有良好的生烃条件与保存条件,但在页岩气勘探过程中,需在考虑区域地质构造的基础上讨论页岩气成藏与保存的有效性。
The silty sandstone interlayers and fracture veins are developed in shale gas reservoir of Wufeng-Longmaxi Formations in the southeastern Chongqing,China.The generation and preservation characteristics of shale gas of well YC2 in Wufeng-Longmaxi Formations were deeply investigated in terms of the organic geochemical characteristics of shales,the microscopic characteristics of silty sandstone interlayers and fracture veins,as well as the characteristics of fluid inclusion.The results indicate that there are two stages of hydrocarbon charging processes in silty sandstone interlayers.Stage 1 occurs at Early Triassic,in which shales are in the lowly mature-mature development stage,consisting of heavy oil inclusions distributed in the quartz grains and residual brown-dark brown asphalt between the quartz grains.Stage 2 occurs at Early Jurassic,in which shales are in the mature development stage,consisting of shale gas inclusions distributed zonally along the micro-fractures of the quartz grains and light oil between the quartz grains.The fracture veins in Wufeng-Longmaxi Formations trap a lot of pure gas inclusions.CH 4 from the shales of Wufeng-Longmaxi Formations is the main composition of the pure gas inclusions.The gas inclusions are trapped mainly in Cretaceous.The shales of Wufeng-Longmaxi Formations in some areas of the southeastern Chongqing have good hydrocarbon generation and preservation conditions.In the process of shale gas exploration,the regional geological structure must be considered for discussion on the effectiveness of the gas accumulation and preservation.
作者
黎琼
欧光习
汪生秀
张敏
吴迪
LI Qiong;OU Guang-xi;WANG Sheng-xiu;ZHANG Min;WU Di(Beijing Research Institute of Uranium Geology,Beijing 100029,China;Key Laboratory of Shale Gas Exploration of Ministry of Natural Resources,Chongqing Institute of Geology and Mineral Resources,Chongqing 401120,China;National Joint Local Engineering Research Center for Shale Gas Exploration and Development,Chongqing Institute of Geology and Mineral Resources,Chongqing 401120,China)
出处
《地球科学与环境学报》
CAS
北大核心
2019年第5期529-540,共12页
Journal of Earth Sciences and Environment
基金
中国地质调查局地质调查项目(DD20160177-02-01)
关键词
地球化学
储层
页岩气
流体包裹体
油气充注
五峰组
龙马溪组
龚滩向斜
重庆
geochemistry
reservoir
shale gas
fluid inclusion
hydrocarbon charging
Wufeng Formation
Longmaxi Formation
Gongtan syncline
Chongqing
