松辽盆地葡北油田油源断裂分类及其对油气分布的控制作用

为了研究松辽盆地北部断裂对葡北油田油气成藏的作用, 基于断层引起的地层变形特征, 通过断层地震特征的精细分析, 重新划分并研究了葡北油田葡萄花油层油源断裂对该油田葡萄花油层成藏的作用。根据断裂是否连接源岩和目的储层, 且在油气成藏期断裂是否活动, 包括断距相对较大的断裂活动和无明显断距的微弱活动, 划分了3种类型的油源断裂: 一是沟通青一段源岩和葡萄花油层且断穿至T₀₆反射层(嫩江组三段底界面)的穿透型油源断裂; 二是连接青一段源岩和葡萄花油层, 在油气成藏期没有明显活动但引起断层端部发生褶皱变形的断层端部褶皱型油源断裂; 三是连接青一段源岩和葡萄花油层在油气成藏期没有明显活动但断层两盘地层存在变形差异特征的断层两盘差异型油源断裂。研究结果表明, 油源断裂与葡北油田葡萄花油层油气平面分布吻合程度更高, 其中, 穿透型油源断裂对油气聚集控制作用最为显著, 揭示了油源断裂的活动强度以及油源断裂与断层圈闭的匹配所控制的油气成藏数量对油气富集的差异性的影响, 该研究对类似区块油源断裂对油气控制作用分析可借鉴参考。

In order to study the role of faults in hydrocarbon accumulation in Pubei Oilfield, northern Songliao Basin, based on the characteristics of formation deformation caused by faults, the oil-source faults in the Putaohua oil layer in Pubei Oilfield were reclassified and their control on hydrocarbon accumulation in the layer were investigated by fine analysis of fault seismic characteristics.According to whether the fault connects the source rock and the target reservoir, and whether the fault is active during the hydrocarbon accumulation period (including the fault activity with relatively large fault throw and the weak activity without obvious fault throw), three types of oil-source faults are divided.Type 1 is the penetrating oil-source fault that connects the source rock of the first member of Qingshankou Formation (K₂qn₁) and the Putaohua oil layer and breaks through the T₀₆ reflector (the bottom interface of the third member of Nenjiang Formation).Type 2 is the oil-source fault with fold deformation at the end and connecting the source rock of K₂qn₁ and the Putaohua oil layer, which has no obvious activity during the hydrocarbon accumulation period but causes fold deformation at the end of the fault.Type 3 is the oil-source fault with differential walls, which connects the source rock of K₂qn₁ and the Putaohua oil layer, without obvious activity during the hydrocarbon accumulation period but with the deformation difference between the two walls.The research shows that the oil-source fault is more consistent with the plane distribution of oil and gas in the Putaohua oil layer.Especially, the penetrating oil-source fault has the most significant control on hydrocarbon accumulation.This reveals the influences of the activity intensity of oil-source faults and the number of hydrocarbon accumulations controlled by the configuration of oil-source fault and fault trap on the differential hydrocarbon accumulation.The research findings can be referential for analyzing the control of oil-source fault on hydrocarbon accumulation in similar blocks.