川西坳陷中段梓潼凹陷烃源岩品质和天然气来源及勘探前景  

Quality of source rocks as well as the source and exploration prospect of natural gas in the Zitong Sag in central part of the Western Sichuan Depression

作　　者：吴小奇[1,2] 杨俊 宋晓波[3] 陈迎宾[1,2] 刘栩[1,2] Xiaoqi WU;Jun YANG;Xiaobo SONG;Yingbin CHEN;Xu LIU(Wuxi Research Institute of Petroleum Geology,Petroleum Exploration and Production Research Institute,SINOPEC,Wuxi 214126,China;Key Laboratory of Hydrocarbon Accumulation,SINOPEC,Wuxi 214126,China;Research Institute of Exploration and Development,Southwest Oil&Gas Branch,SINOPEC,Chengdu 610041,China)

机构地区：[1]中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡214126 [2]中国石化油气成藏重点实验室,江苏无锡214126 [3]中国石化西南油气分公司勘探开发研究院,四川成都610041

出　　处：《天然气地球科学》2024年第5期785-798,共14页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:42172149,U2244209);中国石化科技部项目(编号:P22073,P22132)联合资助。

摘　　要：梓潼凹陷是四川盆地川西坳陷中段唯一尚未取得规模性勘探发现的构造单元,目前对其烃源岩品质、天然气来源及勘探前景认识较为薄弱。研究表明:梓潼凹陷陆相腐殖型烃源岩主要位于上三叠统,普遍处于高—过成熟阶段,其中须家河组三段有机质丰度最高,TOC含量平均为2.46%;而下侏罗统白田坝组泥岩和中三叠统雷口坡组海相碳酸盐岩TOC含量主体小于0.5%,未钻遇规模性有效烃源岩。MY1井须家河组四段天然气为典型煤成气,来自须家河组三段煤系烃源岩;而YX1井雷口坡组四段天然气为油型气,为下伏龙潭组泥质烃源岩生成的原油后期发生裂解所形成。梓潼凹陷不同层系勘探潜力受烃源岩供烃能力、源储组合和输导体系制约,须家河组四段下亚段是最有利的勘探领域,其次为须家河组二段;中上侏罗统和雷口坡组勘探潜力受输导通道的制约。对中、上二叠统天然气勘探潜力的认识分别有赖于对储层物性和台缘带分布范围的进一步研究。The Zitong Sag is the single tectonic unit without large-scale exploration discoveries in the central part of the Western Sichuan Depression in the Sichuan Basin,and the current understandings on the source rock quality,gas source and exploration prospect are weak.This study indicates that,the terrigenous source rocks in the Zitong Sag are mainly in the Upper Triassic strata with high-over maturity,in which the mudstone in the 3rd Member of the Xujiahe Formation displays the highest organic abundance with the average TOC content of 2.46%,whereas the mudstone in the Lower Jurassic Baitianba Formation and carbonate rocks in the Middle Triassic Leikoupo Formation mainly display the TOC contents lower than 0.5%,and the effective source rocks have been rarely revealed.Natural gas from the 4th Member of the Xujiahe Formation in Well MY1 is typical coal-derived gas and derived from the coal-measure source rocks in the 3rd Member of the Xujiahe Formation,whereas the gas from the 4th Member of the Leikoupo Formation of in Well YX1 is oil-associated gas and derived from the argillaceous source rocks in the Upper Permian Longtan Formation.The exploration prospect of different strata in the Zitong Sag is constrained by the hydrocarbon supply capacity of source rocks,source-reservoir assemblage,and transportation system.The lower submember of the 4th Member of the Xujiahe Formation is the most favorable exploration field in the sag followed by the 2nd Member of the Xujiahe Formation.The understanding of exploration potential of the Middle-Upper Jurassic strata and Middle Triassic Leikoupo Formation is significantly constrained by the conducting system,whereas that of the Middle and Upper Permian strata depends on further study of the physical property of the reservoirs and the distribution of the platform margins,respectively.

关 键 词：梓潼凹陷 烃源岩 有机质丰度 天然气 气源对比 勘探前景 

分 类 号：TE122[石油与天然气工程—油气勘探]