Origin and accumulation of the oils from Bamianhe Oilfield, Bohai Bay Basin, Eastern China

Utilizing basic principles and methodologies of geology and organic geochemistry, kinetics of hydrocarbons generation and accumulation, quantitative assessment of crude oils sourced from different source rocks, and hydrocarbons migration pathways for the oils from the Bamianhe Oilfield, the Bohai Bay Basin, Eastern China are discussed. Results of oil-rock correlation showed that the oils were mainly derived from Es4 member (with buried depth >2700 m) of Niuzhuang and Guangli Sags within normal oil window though there is a little amount of mixed immature oils. Quantification of mixed oils with different sources indicated that mature oils account for about 80% of the total oils discovered and immature oils for only 20%. Migration of the oils sourced from the sags is controlled by predominant hydrocarbons migration passages determined by faults, unformalities and favored sandstone reservoir. Results of the origin and migration models for the oils have been recently further testified by considerable quantity of oils discovered in the Bamianhe area, which is obviously playing an important role in guiding further oil exploration.