涠西南凹陷新近系油气成藏主控因素分析

The Key Factors of Neogene Hydrocarbon Accumulation in Weixinan Sag

涠西南凹陷新近系地层已发现多个油气田和含油构造,但分布不均。凹陷中央新近系油藏主要分布于中央断裂带的西段,在凹陷边部的隆起区南北两端均有油藏,但是南北分布差异很大。研究认为,新近系油气藏分布不均主要受多种控制因素影响。其中,凹陷中央的油气主要来源于垂向运移,有效烃源岩、沟源断裂、涠洲组上部泥岩控制油气的垂向运移;古近系运移路径特征、边缘基底古隆起控制油气的横向运移和分布。

Many oil fields and oil-bearing structures have been found in the Neogene strata of Weixinan Sag, but the distribution of Neogene reservoirs is very irregular. In the center of the sag, it mainly distributes in the western part of the central fault zone. In the uplift area of the sag, although it is found at both the north and the south uplift areas, there are great differences between the north and the south. The study shows that the uneven distribution of Neogene reservoirs is mainly affected by many controlling factors. It is believed that the oil and gas in the center of the sag mainly come from vertical migration. Effective source rocks, linking source faults and upper mudstones of Weizhou Formation control the vertical migration of oil and gas. The characteristics of Paleogene migration path and paleo-uplift of marginal basement control the lateral migration and distribution of oil and gas.