渤东地区新近系“脊-断”耦合控藏模式与定量表征

利用渤东地区丰富的钻探资料,开展油气横向与垂向运移路径研究,总结远源型凸起区和斜坡带的油气运聚规律。研究表明,潜山不整合面和馆陶组底部区域砂岩是输导脊的2种通道类型。输导脊是浅层新近系油气富集的基础,它与断层耦合程度控制浅层油气运移。根据输导脊上圈闭与断层的接触方式,"脊-断"耦合关系分为接触式和非接触式,接触式进一步细分为控圈式和非控圈式。只有接触式的"脊-断"耦合关系才利于浅层油气运移,其中控圈式的接触关系浅层运移条件最优越。综合考虑输导脊规模及其与有效烃源岩的接触范围、输导脊上圈闭面积及其与有效烃源岩之间的压差等参数,构建的输导脊油气运聚系数可以较好地反映输导脊的运聚能力。油气富集层系受断层活动强度与区域盖层厚度综合控制,利用断盖比参数可以定量判断,断盖比值0.25和1分别是深层东营组、浅层明下段底部区域盖层遮挡的临界值。输导脊分布的区域是远源油气勘探的重要区带,"脊-断"耦合好的构造是浅层有利勘探目标。

Study on quantitative characterization of "ridge-fault" coupling reservoir-controlling model in the Neogene of Bodong area,Bohai Sea,China

Lateral and vertical favorable migration pathways of hydrocarbon were analyzed based on abundant drilling data of Bodong area,and the hydrocarbon migration and accumulation patterns of uplift and ramp area were established in this paper.It reveals that buried-hill unconformity and regional sandstone layer are essential transporting ridge channels,the existence of deep ridge is fundamental for the accumulation of Neogene hydrocarbon,and shallow hydrocarbon migration is greatly controlled by the coupling of these ridges and faults.According to the assemble style between traps and faults,the coupling relationship are divided into contact-type and non-contact type,and the former can be further divided into trap-controlling type and non-trap controlling one.It shows that the contact type is favorable for shallow hydrocarbon migration,while those trap-controlling types are the most optimum ones.An effective predict method of hydrocarbon accumulation coefficient is proposed by consideration of size and contact area between the transporting ridges and effective source rocks,trap area along transporting ridges and differential pressure in accordance with available drilling results.Hydrocarbon accumulation coefficient is controlled by fault activity and regional seal thickness,ratio between fault throw and cap rock thickness can be used as a semi-quantitative evaluation index.Statistics show that 0.25 and 1 is the threshold of regional seal of Dongying Formation and the Lower Member of Neogene Minghuazhen Formation,respectively.It shows that the distribution area of transporting ridges is important in the exploration of hydrocarbon,and the shallow layers with well coupled "ridge-fault" are the most favorable shallow exploration targets.