渤海湾地区X型正断层及油气意义

X-Pattern Normal Faults in the Offshore Bohai Bay Basin and Its Significance on Hydrocarbon

本文主要利用地震资料解释成果,对渤海湾地区广泛发育的X型正断层的剖面变形特征、形成演化过程和机理及其油气意义进行分析。渤海湾地区X型正断层可分为新生型和继承型两类,在剖面上组合形成对称或非对称的X型形态。新生型和继承型X型正断层具有不同的形成演化过程与控制机理。新生型X型正断层与断裂带的右行走滑作用有关,是在断层的同步滑动过程中形成的。而继承型X型正断层的形成与基底先存断裂的继承性活动密切相关,是基底断裂优先活动的结果。渤海湾地区X型正断层对油气聚集成藏的有利作用主要表现在:有利于构造和地层圈闭的形成,有利于油气发生运移;有利于改善储层物性。与X型正断层相关的构造和地层圈闭是渤海湾地区值得关注的重要油气勘探领域。

X-pattern normal faults developed well in the offshore Bohai Bay basin. On the basis of the interpretation of seismic profiles, the section features, formation, controlling mechanisms and its significance on hydrocarbon of the X-pattern normal faults in the offshore Bohai Bay basin were analyzed. The X-pattern normal faults could be divided into incipient and inherited types, including symmetrical and asymmetrical patterns in the seismic sections. The incipient X-pattern normal faults were related with the dextral strike-slipping movement of faults, and developed during the simultaneous slip on the crossing faults. The formation of the inherited X-pattern normal faults was resulted from the preferentially reactivation of the pre-existing basement faults. The X-pattern normal faults had also important influence on the formation of the structural and subtle traps and hydrocarbon migration, as well as the reservoir properties in the study area. The structural and stratigraphic traps related with the X-pattern normal faults are the favorable objectives for hydrocarbon exploration in the offshore Bohai Bay basin.