伊通盆地西北缘断裂带的性质

Fault Nature of North-West Fault Zone in Yitong Basin and Its Relation with Reservoir Accumulation

以往对伊通盆地西北缘的断裂性质问题认识不清,严重制约了该地区的油气勘探工作。综合利用钻井、露头岩心及地球物理资料,确立了伊通盆地西北缘断裂带在古近纪右行走滑伸展之后、新近纪以来为挤压性质,并发育一系列逆断层及相关褶皱等构造。存在挤压作用的主要依据有以下4点:(1)在靠近西北缘边界的探井岩心中,地层大幅度倾斜或近于直立;(2)盆地西北缘露头出现大量挤压形成的褶皱构造;(3)盆地西北缘地震剖面上普遍存在逆冲构造和花状构造特征;(4)重、磁、电资料也表明盆地西北缘存在挤压现象。勘探证实,伊通盆地西北缘断裂带的挤压性质及伴生构造特征有利于油气的运聚和成藏。该认识有力地指导了伊通盆地的油气勘探,同时也对整个郯庐断裂带东北段的油气勘探战略具指导意义。

The fault nature of north-west area in Yitong Graben used to be obscure, which heavily impedes the oil prospecting works in this area. By using outcrop, core, geophysical data, it is concluded that north-west fault zone in Yitong Basin is compressive and reversed faults which are well developed. A lot of fold structures are shaped at geological outcrops in north-west area of the basin. In prospecting wells near north-west boundary core data show that strata tilted at a large angle, and some even turn perpendicular. Gravity, magnetic and geo- electrical data also show that north-west area in Yitong Graben exits compressive phenomena. Fault composite characteristics are interpreted from high resolution 3D seismic. Fault nature and its characteristics are favorable for reservoir accumulation in the area. This study greatly guides oil exploration of north-west area in Yitong Graben, and also has a guiding meaning to oil prospecting vista of the entire Tancheng-Lujiang fault zone.