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Characteristics and Exploration Potential of Oil and Gas Reservoir in Salsich Block, North Gabon Sub-basin

Guo Nianfa,Liu Zixuan   

  1. Sinopec International Exploration and Production Company
  • Online:2015-03-15 Published:2015-05-21

Abstract: North Gabon Sub-basin experienced the rift period, transition period and passive continental marginal depositing period since the Cretaceous era. Salsich Block is located in North Gabon Sub-basin off the coast of Gabon. Hydrocarbon is accumulated mainly in the postsalt strata series of the Cretaceous System. Hydrocarbon distribution comes under influence of regional structural development. Hydrocarbon accumulation belts are in line with the regional structural strike. The black mudstone of the Upper Cretaceous Azile Formation is the main hydrocarbon source rock of oil and gas reservoirs in Salsich Block. The organic carbon content of source rock is 3-5 percent on average while the organic matter is mainly composed of kerogen type I and II. The reservoirs are subsea turbidite fan sandstone of the Upper Cretaceous Anguille Formation and shallow sea delta sandstone of the Upper Cretaceous Point Clairette Formation. There are two hydrocarbon accumulation models – primary and secondary accumulation patterns with sourcing in lower part and accumulated in the upper part. The characteristics of reservoirs under the two accumulation patterns are quite different from each other. Five structural belts developed in Salsich Block, namely WZ structural belt, OZ structural belt, IE structural belt, NT structural belt and GG structural belt. One structural belt is different from another in terms of oil and gas resources potential. Of those, WZ structural belt is the most favorable one for oil and gas accumulations with unique conditions for oil and gas abundance and a considerable potential for exploration. The oil and gas exploration potential of other structural belts become less desirable owing to influence of comprehensive geological conditions.