歧口凹陷西坡白水头构造沙一段下部油气成藏期次研究

根据储层的成岩序次、油气包裹体特征及含烃盐水包裹体均一温度,结合构造活动特征及烃源岩的演化史,对歧口凹陷西坡白水头构造沙一段下部油气藏进行了成藏期次综合研究。认为该油气藏有三期油气充注过程:第一期发生在馆陶组末到明化镇组下段沉积早中期,约为11.5～8Ma,源区沙三段烃源岩有机质处于低成熟阶段,油气来源不足,成藏规模小;第二期发生在明化镇下段沉积末期到明化镇上段沉积初期,约为5Ma±,白水头构造各主要断层活动强烈,沙三段烃源岩开始进入生排烃高峰,油气运聚规模较大;第三期发生在明化镇上段沉积中晚期到第四系初期,约为3.5～2Ma,烃源岩整体处于生排烃高峰,各大断层活动有所减弱,但仍控制着油气的大规模垂向运移,成藏规模大。

Research on the charge times and stages of oil and gas reservoir in lower Es, of Baisbuitou structure at west slope in Qikou depression.

According to diagenetic sequences of reservoir, characteristic of petroleum inclusion and homogenization temperature, combining with characteristic of structural activity and evolution of source rock, this paper analyzes the reservoir charge history of lower segment of Es1 at Baishuitou Structure, west slope of Qikou Depression. It can be concluded that there are three stages of hydrocarbon injection, with the period ranging 11. 5-8Ma, 5Ma and 3. 5-2 Ma respectively. The first stage is from the end of Ng to early-mid lower Nm when the source rock from Es3 come within low maturity, so the oil source is deficient and the scale of oil accumulation is small. The second stage is at the intersection of upper and lower segment of Nm when the activity of the main faults is strong and the source rock begins entering oil-generating peak, so the scale of oil migration and accumulation is larger. The third stage is from mid-late upper Nm to early Quaternary when the source rock is entirely mature and the activity of fault still controls the vertical migration of oil, so the charge scale of oil and gas is largest.