鄂西海槽地质结构特征及研究新进展

Characteristics and Research Progress of Geological Structure of Western Hubei Trough

鄂西海槽主体位于中扬子西部湘鄂西褶皱带,为晚元古-早古生代一拉张裂陷槽。海槽起始于下震旦统陡山沱期,形成于上震旦统灯影期,消亡于早寒武世晚期,裂陷活动塑造了区内台盆分异的格局,控制着主要烃源层和储盖层的分布。裂陷槽周缘为台盆过渡带,发育台地边缘颗粒滩沉积,为下组合重要的储层类型。台缘带主要分布在利川-彭水以及宜昌-桑植一带,且海槽具有西陡东缓的特征。利用大量的地震资料以及深层钻井资料,通过分析震旦系-寒武系地层厚度变化特征,精细编制寒武系地层等厚图,确定鄂西海槽西缘发育北西向分支海槽,推进了鄂西渝东下古生界勘探进程。

The western Hubei trough is located in the west Hunan and Hubei fold belt in the western part of the middle Yangtze River,which is an extensional rift trough in Late Proterozoic to Early Paleozoic.The trough originated in the Dushantuo period of the Lower Sinian,formed in the Dengying period of the Upper Sinian,and died out in the late Early Cambrian period.Rifting activities have shaped the pattern of platform-basin differentiation and controlled the distribution of main hydrocarbon source rocks and reservoir cap rocks.The periphery of the rift trough is the transitional zone of the platform-basin,which was developed with the granular beach deposits on the edge of the platform,is an important reservoir type.The platform edge is mainly located in the areas of Lichuan-Pengshui and Yichang-Sangzhi,and the trough is characterized by steep slope at west and gentle slope at east.Based on a large number of seismic data and deep drilling data,the thickness variation characteristics of Sinian-Cambrian strata are analyzed,the isothickness maps of Cambrian strata are compiled,the NW branch trough was developed in the west edge of the western Hubei,and the exploration process of the lower Paleozoic in the east of Chongqing is advanced.