渤海湾盆地东濮凹陷不同区带油气成藏期差异性及主控因素

东濮凹陷是渤海湾盆地典型富油气凹陷,利用烃源岩生排烃史模拟和储层流体包裹体分析,对凹陷内不同区带、不同层系油气藏的形成时期及差异性进行了系统研究。结果表明,研究区存在两期成藏:第一期为古近纪东营组沉积后期至抬升初期,第二期为新近纪明化镇组沉积末期,其中第一期为主成藏期。不同区带、不同层系油气充注成藏时期存在明显差异:第一期成藏范围广泛,在全区均有分布,第二期成藏则主要分布于近生烃凹陷区;中浅部层系多为第一期单期成藏,深部层系多为两期成藏,第二成藏期主要分布于深部主力生烃层系中。不同区带及不同层系成藏的差异性主要受控于烃源岩主生排烃期断层活动性和高成熟烃源岩的分布。

Differences and Main Controlling Factors of Accumulation Periods in Dongpu Sag, Bohai Bay Basin

Dongpu sag is a typical hydrocarbon rich sag in Bohai Bay Basin. Based on the methods of generation and expulsion stages of major hydrocarbon source rocks and fluid inclusion analysis, the oil and gas accumulation periods of Paleogene in Dongpu sag were studied. The results showed that the hydrocarbon accumulation period was divided into two stages. The first stage was from late Dongying deposition period to the early uplift stages, and the second was from the late Minghuazhen deposition period to the Quaternary. The first stage was the main accumulation stage. The accumulation periods of different parts and different layers was studied and compared. The main controlling factors of the differences were analyzed. The oil and gas reservoirs generated in the first phase were extensively distributed and covering all the area; By contrast the oil and gas reservoirs generated in the second stage were mainly distributed in the area near the hydrocarbon generation sags. Reservoirs formed in the fist period were extensively distributed and covering all the area. By contrast, reservoirs generated in the second period were mainly distributed near the hydrocarbon generation sags. Reservoirs formed in the second period were mainly concentrated in the sourse rock layers. The differences were mainly controlled by fault activity and the distribution of high mature source rocks.