复合超压生烃系统内不同成因油气的运移流向分析

牛庄洼陷2套生油岩纵向上叠置,有机地球化学特征、成烃期次及油气运聚过程都存在差异,并伴有异常流体压力,这就构成了复合型超压生烃系统.基于油-源对比和同源油气藏空间分布规律,对叠合型超压生烃系统油气运移流向的差异性进行了分析.研究表明,在断层活动的诱发下,超压驱动"沙三下源型"油主要发生纵向运移;但在超压带盖下"沙四上源型"油主要发生侧向运移,而纵向运移在超压系统发育区相对不活跃.超压系统的自组织行为对油气运移流向具有重要的控制作用,导致"沙三下源型"和"沙四上源型"油气运移及分布规律差异较大.通过复合型超压生烃系统内不同成因的油气运移流向分析,可以进一步认识研究区油气运移和富集规律,进而"分源"挖掘油气勘探潜力.

Analysis of the migration direction of two different types of petroleum in composite overpressure hydrocarbon generation system in Niuzhuang Subsag

There is a composite overpressure hydrocarbon generation system in Niuzhang Subsag,Jiyang Sag.It is composed of two sets of vertically superimposed source rocks (Es3x and Es4s),and there is over-pressure of fluid in it.The two sets of source rock are different in organic geochemical feature,hydrocarbon generation periods and hydrocarbon migration and accumulation process.According to oil-source correlation and the spatial distribution law of homologous hydrocarbon reservoirs,the difference in the hydrocarbon migration direction of the two sets of source rock is studied.It is shown that the hydrocarbon from Es3xsource rock mainly vertically migrates under the induction of fault activities;while the hydrocarbon from Es4s source rock mainly laterally migrates underneath the overpressure cap rock,the vertical migration is not active in the overpressure development area.The self-organization effect of the overpressure hydrocarbon generation system obviously controls the directions of hydrocarbon migration,which causes the greater difference in the migration direction and distribution law of the hydrocarbon from Es3x and Es4s.The analysis of the migration direction of the hydrocarbon from different oil sources in the composite overpressure hydrocarbon generation system can provide help for the recognition of the hydrocarbon migration and accumulation law and the hydrocarbon exploration potential.