Sedimentary characteristics of the Xinbei oilfield and their controls on hydrocarbon accumulation

Abstract：The Xinbei Oilfield, located in the northern part of the Kendong buried-hill drape tectonic zone, Bohai Gulf basin. Its exploration and development are still in the primary phase. In order to know the reservoir characteristics and accumulation rule of the oilfield, based on the exploration and development practice, the stratigraphic characteristics, sedimentary characteristics and reservoir characteristics were studied. The sedimentary system of the oilfield consists in ascending order of Paleogene lacustrine facies and Neogene fluvial facies (including braided stream sediments, meandering river sediments and anastomosing river sediments). Braided stream sediments can be subdivided into two subfacies: diara (channel sand bars) and channel floor lag；meandering river sediments can be subdivided into three subfacies: channel, bank, and flood plain；and anastomosing river sediments can be subdivided into two subfacies: channel and flood plain. The main reservoir of the Xinbei oilfield is meandering river sediments, and the point bar and diara subfacies have the best physical properties for hydrocarbons accumulation. The above research results show strong controlling effects of the sedimentary characteristics on hydrocarbon accumulation. The main reservoir type is the lithologic reservoir.