三肇凹陷扶杨油层源断裂的再认识及其对成藏的控制作用

Source faults of F,Y oil layer in Sanzhao Depression and its control to oil accumulation

对三肇凹陷青一段源岩生成的油向下伏扶杨油层"倒灌"运移通道类型及分布特征研究表明,三肇凹陷扶杨油层源断裂不是过去认为的从青一段底(T2)断至嫩三段底的断裂,而应为上部消失于青一段源岩中的T2断裂。这些断裂主要为坳陷期活动的断裂和断陷期形成、坳陷期继续活动的断裂,在整个凹陷分布广泛。三肇凹陷青一段源岩生成的油向下"倒灌"运移距离主要受青一段源岩古超压值与油"倒灌"运移阻力差的控制,同时还受到被T2源断裂错断的扶杨油层砂泥组合关系的影响。青一段源岩生成的油向下"倒灌"运移的实际距离可达到300m,高值区主要分布在油田区域内。T2源断裂对油成藏与分布的控制作用表现在:T2源断裂发育区控制油聚集区域;T2源断裂发育程度控制着油"倒灌"运移的距离;T2源断裂附近高断块圈闭有利于油聚集成藏;距T2源断裂的距离控制着油井产能。

The research on the characteristics of oil migration mechansim and pathway of oil migrating from K1qn1 source rocks downward to F,Y oil layer in Sanzhao Depression shows that the source faults of F,Y oil layer should be the T2 faults. The upper part of those faults disappeared in K1qn1 source rocks,and the main faults just cut through T2,along from T2 to T3,from T2 to T4 and from T2 to T5 and distributed in the whole depression. The migration distance of oil downward from K1qn1 source rocks in Sanzhao Depression is mainly influenced by the difference between ancient overpressure of K1qn1 source rock and flow resistance during the process of migration downward and also influenced by combination way of faulted sandstone and mudstone in F,Y oil layer. It makes the deviation of actual downward migration distance with the theoretical migration distance. The actual distance of oil downward from K1qn1 source rocks is 300m,and the high-value area mainly distributed in oil fields. The control factors of source faults to oil accumulation and distribution are given. The development area of source faults controls the area of oil distribution. The development degree of source faults controls oil downward migration distance. The high fault blocks nearby source faults are favorable for oil accumulation in F,Y oil layer. The distance to source faults controls the productivity of oil wells.