渤海湾盆地饶阳凹陷新近系油气富集特点与主控因素

Enrichment characteristics and major controlling factors of hydrocarbons in the Neogene of Raoyang Depression,Bohai Bay Basin

根据渤海湾盆地饶阳凹陷新近系油气成藏背景及分布特征,探讨了新近系油气富集特点与主要控制因素。研究区新近系油气来源于古近系沙一下和沙三上亚段烃源岩,平面上油气富集于主力生烃洼陷中心附近、新近纪断裂活动性较强且砂泥比适中的地区,油气呈条带状富集展布;纵向上,新近系油气主要富集于馆陶组,与下伏古近系、前古近系层系中的油气分布呈互补关系。新近系油气富集的主控因素包括:主要生烃洼陷控制油气的宏观分布格局,新近纪油源断裂活动时间和强度决定油气纵向输导能力及富集区块,古近系碎屑岩和前古近系碳酸盐岩潜山圈闭的发育影响了新近系油气的富集程度,盖层厚度和质量影响新近系油藏的含油高度。

Based on accumulations and distributional characteristics of hydrocarbons in the Neogene of the Raoyang Depression,Bohai Bay Basin,we discussed accumulation characteristics and major controlling factors of Neogene hydrocarbons.Oil and gas in the Neogene of the study area are mainly derived from the lower Es1 and upper Es3 source rocks of the Paleogene.Laterally,hydrocarbons are accumulated in zones either adjacent to the center of primary hydrocarbon-generative sub-depressions or with stronger Neogene fault activities and an appropriate sand-to-shale ratio,where hydrocarbons are distributed in a banded pattern.Vertically,hydrocarbons are mainly accumulated in the Neogene Guantao Formation,showing a complementary correlation with hydrocarbon distributions in underlying Paleogene and pre-Tertiary strata.Major controlling factors of hydrocarbon accumulations include： the oil and gas distribution in general is controlled by primary hydrocarbon-generative sub-depressions;the vertical transport capacity and concentrated blocks of hydrocarbons are dominated by the time span and intensity of Neogene fault activities;the accumulation extent of Neogene hydrocarbons is affected by the development of Paleogene clasolite and pre-Paleogene carbonate buried-hill traps;and the height of oil columns in Neogene reservoirs is dependent on the thickness and quality of cap rocks.