松辽盆地敖古拉断裂带构造演化及断控油气聚集机制

Structural Evolution and Fault-controlled Hydrocarbon Accumulation Mechanism of Aogula Fault Zone in Songliao Basin

松辽盆地敖古拉断裂带呈现出复杂的运动学特征,各成藏主控要素时空匹配关系研究难度大,为油藏形态精准刻画带来了挑战。针对该问题,综合地质、地震解剖和钻井资料分析,梳理构造发育史及断裂成因,并在成藏认识的基础上,明确断裂控制油气富集的机制。研究区断裂密集带可划分为2个级别,并根据断层与层位切割关系将断层分为3类。研究表明:敖古拉断裂带由2条反“S”形主干断裂组成,历经断陷期、坳陷期以及反转期3个阶段;断陷期断裂带活动强度与伸展率最大,坳陷期逐渐减弱,伴生多条反向调节断层,反转期断层活动强度与伸展率再次增强;油源断层是沟通烃源岩和圈闭的垂向运移通道,控制了与断层相关圈闭的形成,为油气运移、聚集提供了有利条件。研究结果能够为进一步寻找有利勘探目标及增储上产提供理论依据。

The Aogula Fault Zone in the Songliao Basin exhibits complex kinematic characteristics,making the study of the spatiotemporal matching relationships of various reservoir-forming controlling factors challenging,which brings challenges to the accurate characterization of reservoir morphology.To address this issue,a comprehensive analysis of geological,seismic interpretation,and drilling data was conducted to understand the structural development history and fault causes.Based on the understanding of reservoir formation,the mechanisms of fault-controlled oil and gas accumulation were clarified.The fault-dense zone in the study area can be divided into two levels,and the faults are classified into three types based on their relationship with stratigraphic position.The study reveals that the Aogula Fault Zone is composed of two antithetic"S"-shaped main faults,experiencing three stages:faulting,sagging,and inversion.During the faulting stage,the activity intensity and elongation percentage of the fault zone are the highest,gradually weakening during the sagging stage,accompanied by multiple reverse regulating faults,and strengthening again during the inversion stage.Oil-source faults serve as vertical migration pathways connecting source rocks and traps,controlling the formation of fault-related traps and providing favorable conditions for oil and gas migration and accumulation.The research results can provide theoretical support for further exploration targeting and reserve enhancement.