蜀南地区长兴组顶部岩溶不整合的发现及其油气地质意义  

Discovery and geologic significance of paleokarst unconformity between Changxing Formation and Feixianguan Formation in Shunan area of Sichuan Basin

作　　者：罗冰[1] 谭秀成[1] 李凌[1] 刘宏[1] 夏吉文[2] 杜本强[2] 刘晓光[1] 牟晓慧[1] 

机构地区：[1]西南石油大学资源与环境学院,四川成都610500 [2]中国石油西南油气田分公司蜀南气矿,四川泸州646001

出　　处：《石油学报》2010年第3期408-414,共7页Acta Petrolei Sinica

基　　金：中国石油天然气集团公司石油科技中青年创新基金项目(06E1018);四川省重点学科建设项目(SZD0414)联合资助

摘　　要：对四川盆地二叠系和三叠系接触关系的认识长期存在较大分歧。通过对钻井、岩心等资料的研究发现,蜀南地区长兴组钻进过程中出现大量钻具放空现象,岩心上见大量的溶沟、溶缝、溶洞及岩溶角砾。综合分析认为蜀南地区长兴组与飞仙关组并非连续沉积,其间存在沉积间断,长兴组古岩溶作用发育,形成了长兴组顶部古岩溶不整合。泸州古隆起的持续发展和二叠纪末期一次重大海退引起的长时期暴露溶蚀是蜀南地区长兴组古岩溶形成的关键。古岩溶对碳酸盐岩的储集性能具有较强的优化改造能力,古岩溶不整合面可以作为油气长距离运移的优质通道,岩溶斜坡带是油气成藏的有利区带。长兴组顶部古岩溶不整合的发现为区内二叠系和三叠系非整合接触找到了直接证据,对今后蜀南地区乃至四川盆地长兴组的油气勘探具有指导意义。There exists a long-time dispute for the contact relation between the Permian and the Triassic in Shunan area of Sichuan Basin.The drilling break phenomenon commonly occurred during the drilling process,and a great quantity of karrens,dissolved fractures,caves and karst breccia were found in the rock cores.The comprehensive analysis shows that there is not the successive sedimentation between Changxing Formation and Feixianguan Formation in the Shunan area of Sichuan Basin.The paleokarst in Changxing Formation is highly-developed and causes the paleokarst unconformity at the top of Changxing Formation.The Luzhou palaeo-high embryo and the exposed corrosion due to a major regression at the end of the Permian are the key factors to form and develop paleokarst.Actually,the paleokarst can optimize the hydrocarbon accumulation capacity in carbonate rocks.The uncomfortable surface can be taken as the high-quality channel of the long-distance hydrocarbon migration.The discovery of the paleokarst unconformity at the top of Changxing Formation proved the existence of the uncomfortable contact relation between the Permian and the Triassic.The further exploration of biothermal limestone in Changxing Formation of Sichuan Basin was presented.

关 键 词：四川盆地 蜀南地区 长兴组 识别标志 古岩溶 不整合 油气成藏 

分 类 号：TE111.3[石油与天然气工程—油气勘探]