莘县凹陷下第三系含油气系统分析

莘县凹陷位于渤海湾盆地临清坳陷东部,其主力烃源岩发育在沙河街组一段、三段及四段+孔店组.馆陶组沉积末期,烃源岩进入生、排烃高峰期,为含油气系统形成的关键时刻.依据油气显示及油源对比结果,该凹陷下第三系可划分为两大含油气系统:沙河街组三段已知含油气系统由沙河街组三段下亚段和中、上亚段两个子系统组成,前一子系统已发现贾2井、莘4井油藏,后一子系统目前尚未发现油气显示;沙河街组四段+孔店组推测含油气系统由沙河街组四段和孔店组两个子系统组成,目前均未发现油气显示.含油气系统内主要发育构造、构造-岩性及岩性3类油气藏,形成于中新世.生烃凹陷、生烃时期及断层封堵性控制了油气藏的分布,堂邑次凹环洼带为有利的成藏区.

ANALYSIS OF LOWER TERTIARY PETROLEUM SYSTEMS IN SHENXIAN SAG

Shenxian Sag is situated in the east part of Linqing Depression in Bohai Bay Basin.The main source rocks are Sha 1,Sha 3,Sha 4 members and the Kongdian Formation.The late depositional stage of the Guantao Formation was the peak stage of oil generation and expulsion of the source rocks and also the critical period of the formation of petroleum systems.According to oil shows and oil source correlation,the Lower Tertiary in the sag could be divided into two petroleum systems:1.the known Sha 3 member pertoleum system which contains two subsystems such as the lower Sha 3 submember and the middle and upper Sha 3 submember subsystems.Oil pools of Jia 2 Well and Shen 4 Well were discovered in the first subsystem but no oil shows have been found in the last subsystem;2.the deduced petroleum system of Sha 4 member and the Kongdian Formation could be divided into Sha 4 member subsystem and Kongdian Formation subsystem,and no oil shows have been discovered in the second subsystems.The oil pools developed within the petroleum systems are mainly srtuctural oil pool,structural lithologic oil pool and lithologic oil pool which were formed in Miocen Epoch.The distribution of oil pools are controlled by hydrocarbon generation sag,hydrocarbon generation stage and fault sealing ability.It is considered that circumsag belt in Tangyi Subsag is favourable for hydrocarbon pool formation.