断陷湖盆细粒沉积区砂体分布控制因素

作为断陷型盆地辽东凹陷的重要组成单元,辽东凹陷南部洼陷具有典型的"西断东超"箕状构造。通过钻井、测井分析以及大量地震剖面的精细解剖,认为辽东凹陷南部洼陷存在北东方向和东部两处物源,其中北东方向物源为主要物源,波及范围覆盖整个洼陷,东部方向为次要物源,波及范围局限于缓坡地带。研究区东部缓坡发育沟谷体系和构造坡折带,构造坡折带包括断裂坡折带和挠曲坡折带,断裂坡折根据断裂组合样式又表现为单阶式和断阶式。沉积区与物源的相对距离、沟谷体系和构造坡折带主要控制古近系砂岩储层的分布样式。近物源的三角洲前缘前积砂体和滑塌浊积体发育区以及东部缓坡带构造坡折的坡角是寻找砂岩储层的有利场所。

Controlling Factors of Sandbody Distribution on the Fine-grained Sedimentary Area in Lacustrine Fault Basins

Liaodong Sag is a fault basin. As the main part of Liaodong Sag, sourthern subsag is a half graben, characterized by wast-faulting and east-overlapping. Detailed studies, with data from drilling, logging and seismic survey, have showed that there exist two sources: the main one is northeast, which covers all of the study area, and another is east that just gentle slope zone is based on. Gully system and structural slope break zone,including fracture slope break and flexure slope break, are developed in the eastern gentle slope area. According to the combination features of faults, single-faulted and stepped-faulted fracture slope break can be differentiated. Main controlling factors for sandstone distribution are distance between deposition area and provenance area, gully system and location of structural slope break zone.Proximal delta foreset sand body, slumped turbidites and slope angle of structural slope break in eastern gentle slope area are favorable well-developed area for sandstone reservoirs.