塔里木盆地西南缘的构造特征与油气聚集规律

Structural Characteristics and Petroleum Accumulation of Thrust Belt in Southwestern Margin of Tarim Basin

塔里木盆地西南缘前陆冲断带主要形成于新生代,由3排东西走向的背斜带组成,共有十几个滑脱背斜。该冲断带有两个重要的滑脱面,一个是上震旦统克孜苏胡木组与上覆上古生界之间的区域角度不整合面,另一个位于下第三系底部的膏泥岩层中,冲断带发育于沿滑脱面产生的区域性滑脱体中。塔西南地区发育有多套生油岩系,最重要的有两套,即石炭系一下二叠统和侏罗系。油气的运移、聚集与冲断带内复杂的断裂系统有着密切的联系,主断裂面是区域性运移的通道,次级断裂面和分支断层在油气垂向运移和聚集中起着重要作用。由此形成了冲断带内的两种油气藏类型,即位于深层古生界中的原生油气藏和浅部新生界的次生油气藏,目前在柯克亚下第三系中所发现的均为次生凝析气藏。根据多种资料分析,冲断带中最有利的勘探目标是第二排背斜带。

The foreland thrust belt in southwestern margin of the Tarim basin, mainly formed in Cenozoic era,can be subdivided into three rows anticline belts occurred northwestly in strike,and into ten decollemant folds and more.An oil and gas field has been discovered in the Kekeya anticline in the second anticline belt.The source beds of the thrust belt are Carboniferous-Permian and Jurassic.The hydrocarbons generated are migrated along regional decollemant surfaces from south to north,and the branch faults originated from major faults control and affect hydrocarbon accumulation.Two types of oil and pools are recognized,they are primary type in Paleozoic erathem and secondary one in Cenozoic erathem.The best targets are in the second row anticline belts.