中扬子二叠-三叠系裂陷盆地沉积充填及对油气勘探的指示意义  

Sedimentary Filling of the Permian-Triassic Rift Basin in the Middle Yangtze Region and Its Significance for Oil and Gas Exploration

作　　者：刘漪[1] Liu Yi(Exploration and Development Research Institute,SINOPEC Jianghan Oilfield Company,Wuhan Hubei 430223)

机构地区：[1]中国石化江汉油田分公司勘探开发研究院,湖北武汉430223

出　　处：《中外能源》2020年第4期31-38,共8页Sino-Global Energy

基　　金：国家科技重大专项“中扬子地区海相层系油气成藏条件及勘探评价”(编号:2017ZX05005003-008)资助。

摘　　要：裂陷作用(槽)对油气的聚集具有明显的控制作用,目前四川盆地发现的几大油气中心均处于裂陷槽周缘,如普光、元坝、龙岗、磨溪-高石梯等气田。本文在前人研究基础上,系统开展了中扬子地区二叠-三叠系裂陷盆地沉积演化特征研究,划分出整体沉降阶段、初始裂陷阶段、裂陷扩张阶段、裂陷萎缩消亡阶段四个演化发展阶段。其中二叠纪栖霞期,中扬子地区地壳整体沉降,以相对均一化台地沉积为特征;茅口早期在中扬子东北部大洪山地区率先出现拉张裂陷,茅口晚期扩张到城口-鄂西地区;晚二叠世长兴期裂陷作用达到鼎盛,台地和盆地分异充分,在长兴期形成适合生物礁滩发育的台地边缘礁和台缘及台内生屑滩储层;早三叠世裂陷盆地进入萎缩阶段,随着盆地不断充填,台盆分异的格局逐渐趋于均一化,呈现出缓坡型碳酸盐岩台地特点,填平补齐形成的斜坡环境控制着大冶组颗粒滩的展布和迁移变化。裂陷槽控制了礁滩储层的分布,长兴组和大冶组礁滩储层明显受裂陷槽控制,具有一定的继承性,主要分布在江汉平原南部的江南台地北缘和鄂西渝东地区鄂西裂陷槽的西缘以及开江-梁平陆棚东南端。Rifting plays an important role in controlling the hydrocarbon accumulation.At present,several major oil and gas centers found in SichuanBasin locate around the aulacogen,such as Puguang,Yuanba,Longgang,Moxi-Gaoshiti gasfield,etc.On the basis of previous studies,the sedimentary evolution characteristics of the Permian-Triassic rift basin in the middle Yangtze region are systematically developed,and it is divided into four evolution stages :overall subsidence stage,initial rift stage,rift expansion stage,and rift shrinkage and extinction stage.In the Qixian age of Permian,the crust in the middle Yangtze region was subsided in general with the characteristics of relatively uniform platform sedimentation.In the early stage of Maokou,the extensional rifting took place in Dahongshan area in the northeast of the middle Yangtze region,and extended to the Chengkou-western Hubei area in the late stage of Maokou;in the Changxing of late Permian,the rifting reached its peak,and the platform and basin were fully differentiated,the platform marginal reef and bioclastic reservoir at platform margin and in the platform suitable for the development of reef shoals are formed.As the rift basin in the early Triassic entered the shrinking stage,the pattern of platform basin differentiation gradually tended to be uniform with the continuous basin filling,which shows the characteristics of carbonate platform at gentle slope,and the slope environment formed by filling and leveling controlled the distribution and migration of grain beach in Daye Formation.The aulacogen controls the distribution of reef beach reser-voir.The reef beach reservoir of Changxing and Daye Formations is obviously controlled by the aulacogen,which has certain inheritance.It mainly distributes in the north margin of Jiangnan platform in the south of Jianghan Plain,the west margin of the western Hubei aulacogen in the western Hubei and eastern Chongqing and the southeast end of Kaijiang-Liangping shelf.

关 键 词：鄂西裂陷槽 二叠-三叠系裂陷盆地 二叠-三叠系礁滩 

分 类 号：P618.13[天文地球—矿床学]