渤海湾盆地南堡凹陷断层对油气运聚的控制作用

Control of Faults on Hydrocarbon Migration and Accumulation in Nanpu Sag,Bohai Bay Basin

在对南堡凹陷断层类型划分的基础上,利用地质统计法和地化分析等技术手段,从宏观到微观多个方面阐述了南堡凹陷断层对油气运聚的控制作用。根据断层的发育历史,将南堡凹陷断层划分为3类:长期活动型(Ⅰ类)、早期活动型(Ⅱ类)和晚期活动型(Ⅲ类)。其中Ⅰ类断层大多沟通油源,是油气纵向运移的主要通道,由于其多期活动,形成了南堡凹陷多套含油层系纵向上相互叠置的局面。断层活动的时期和强度控制油气纵向上的分配,而且油气在平面上主要分布在油源断层附近的断块圈闭中。断层封闭性在时间上具有明显的差异性,在油气运聚过程中扮演输导和封堵双重角色。反向遮挡断层圈闭无论在油气藏数量还是在烃柱高度方面均明显好于顺向断层遮挡圈闭,是南堡凹陷油气勘探的有利目标。断层遮挡圈闭的储量规模受断层封闭性影响,准确评价遮挡断层的封闭能力对于提高钻探成功率具有重要意义。

Based on the classification of faults,using geology statistics and geochemical analysis,the controlling effects of faults on hydrocarbon migration and accumulation in Nanpu Sag are expatiated from macroscopic aspects to microscopic aspects.Faults are divided into three types including the long active fault,the early active fault and the lately active fault.The long active fault,acting as source fault,was important pathway for vertical hydrocarbon migration,and multi oil-bearing layers were formed as a result of multiphase activity of the long active fault.The vertical distribution of hydrocarbon was controlled by the phase and intensity of fault activities,and the reservoir was distributed in the traps surrounding source faults.The function of fault for hydrocarbon migration and accumulation was various in different time.The reverse fault-screened trap has better oil-bearing property than the co-dip fault-screened trap,which is favorable target for oil exploration.The reservoir scale of fault-screened trap was controlled by sealing ability of screened fault,so the estimation of fault-sealing has great significance for improving the success rate of drilling.