博兴洼陷油气成因类型及深层勘探潜力

Petroleum genetic types and indepth exploration potential in the Bo xing subsag

根据博兴洼陷原油生物标志物的特征 ,可在该区辨认出四类不同成因的原油。低成熟的油气来自沙四段上亚段低成熟烃源岩 ;而成熟的油气分别来自沙三段中下亚段和沙四段上亚段成熟烃源岩。沙四段上亚段低熟原油与沙三段成熟原油分布广泛 ,主要形成“自生自储”油藏 ;混源油主要分布在断裂带附近 ;而沙四段上亚段成熟油分布局限 ,可能是勘探程度低之故。根据沙四段上亚段烃源岩的性质 ,成熟油的资源潜力不可小视 。

According to the characteristics of the crude biomarkers in the Boxing subsag, four genetic types of crude can be identified. Lowmature hydrocarbon generated from lowmature hydrocarbon source rocks in the upper section of Es 4, while the mature hydrocarbon originated from the mature hydrocarbon source rocks in the middlelower section of Es 3 and upper section of Es 4 in the sag respectively. The lowmature crude from upper section of Es 4 and mature crude from Es 3 distribute widely and forms autogenerated and autoaccumulated reservoirs. The mixed crude is distributed along the faulted zone. But, the mature oil from upper Es 4 has a limited distribution, which probably results from low degree of exploration. The resources potential of mature crude from Es 4 cannot be underestimated based on the attribute of hydrocarbon source rocks in upper Es 4. The middlelower Es 4 and Kongdian Formation at the depth of the subsag can be major reservoirs accumulating this kind of oil.