断裂密集带样式及其对油气成藏的控制作用——以松辽盆地扶新隆起带杨大城子油层为例

杨大城子油层现已成为松辽盆地南部油气勘探的重点层位之一。杨大城子油层油藏围绕T2断裂密集带分布,关于断裂密集带如何控制油气运移,什么样式的断裂密集带有利于油气聚集,断裂密集带什么部位有利于油气富集等问题还没有形成统一的认识。通过地震和构造资料总结断裂密集带平、剖面特征,扶新隆起带杨大城子油层主要发育4种断裂密集带,即反向断阶带、反向断阶￣地堑￣反向断阶带、反式断阶￣地堑￣顺向断阶带、反式断阶￣地堑￣地垒带。当断裂密集带与砂体方向大角度相交时,易形成岩性￣断层圈闭,断裂密集带两侧的地垒和反向断阶是油气聚集的有利场所;当断裂密集带与砂体方向近平行时,断裂带主要起油气疏导作用。

Types of fault-intensive belts and their control on hydrocarbon accumulation:a case study of Yangdachengzi oil layer in Fuxin Uplift,Songliao Basin

Yangdachengzi oil layer has become one of the key exploration horizons in southern Songliao Basin in recent years.However,the reservoirs of Yangdachengzi oil layer distribute around T2 fault-intensive zone.There is no unified understanding on how the fault-intensive zone controls the oil and gas migration,what type of fault-intensive zone is beneficial to oil and gas accumulation,and what part of fault-intensive zone is conducive to hydrocarbon accumulation.Based on seismic and structural data,the horizontal and profile characteristics of the fault-intensive zone are summarized.Four types of fault-intensive zones are mainly developed in the Yangdachengzi oil layer,Fuxin Uplift:antithetic fault terrace belt,antithetic fault terrace-graben-antithetic fault terrace belt,antithetic fault terrace-graben-consequent fault terrace belt,and antithetic fault terrace-graben-horst belt.When fault-intensive zone intersects with sand body direction at a large angle,lithology-fault trap is easily formed;the horsts and antithetic fault terraces on both sides of the fault-intensive zone are favorable places for hydrocarbon accumulation.When fault-intensive zone is nearly parallel to sand body direction,fault zone plays a major role in guiding oil and gas.