渤中凹陷典型富油气区油源断层差异活动与油气富集关系

Relationship between differential activity of source faults and petroleum enrichment in typical oil-rich regions of Bozhong sag

以渤中凹陷典型富油气区为研究对象,探讨了该富油凹陷油源断层差异活动与油气富集和分布之间的关系。结果表明:研究区不同构造带内油气主要沿油源断层分布,由凸起带向斜坡带方向,油气富集层位逐渐由新近系向古近系及前古近系潜山过渡,且断层平均活动强度逐渐降低;新生代以来断层活动速率整体表现出强-弱--强的演化规律,新近系油气主要富集于油源断层差异活动系数> 1. 8且晚期断层活动速率<33 m/Ma的断层附近;凸起带边界油源断层长期活动,有利于新近系油气的富集,倾末端油源断层在烃源岩排烃期早、中期活动较强且晚期活动较弱,控制了深、浅层多层系的油气富集,斜坡带油源断层较少且在烃源岩排烃晚期活动强烈,油气主要富集于古近系及前古近系潜山。

Selecting typical oil-rich regions in Bozhong sag as the research object,the relationship between differential activity of source faults and petroleum enrichment and distribution is studied in the oil-rich sag. The results indicate that: petroleum is mainly distributed along the source faults in various tectonic belts,from bulges to slopes,the strata of oil and gas accumulation gradually shifts from Neogene System to Paleogene System and preTertiary buried hill with the average activity of source faults declining; activity rates of source faults since Paleogene have an overall trend of high-low-high,a source fault is propitious for the enrichment of Neogene reservoirs when the source fault’s differential of activity is above 1. 8 as well as the activity rate of the source fault in later poolforming period is below 33 meters/million years; main boundary source faults along bulges with long-term activity is attributed to hydrocarbon accumulation in Neogene strata,source faults in the dip end of bulges with high activity rate in the early and main period and low activity rate in the later period of hydrocarbon expulsion from source rocks are beneficial for hydrocarbon accumulation in both shallow and deep strata,whereas the slope belts have lesssource faults with high activity rates in the later period of hydrocarbon expulsion from source rocks,which is unbeneficial for Neogene reservoirs,resulting in the hydrocarbon accumulation in Paleogene System and pre-Tertiary buried hill.