The Gulf of Guinea Province as defined by the U.S. Geological Survey (USGS) consists of the coastal and offshore areas of Cote d'Ivoire, Ghana, Togo, and Benin, and the western part of the coast of Nigeria, from the Liberian border east to the west edge of the Niger Delta. The province includes the Ivory Coast, Tano, Central, Saltpond, Keta, and Benin Basins and the Dahomey Embayment. The area has had relatively little hydrocarbon exploration since 1968, with only 33 small to moderate-sized oil and gas fields having been discovered prior to the USGS assessment. Most discoveries to 1995 have been located in water depths less than 500 m. Since 1995, only eight new offshore discoveries have been made, with four of the discoveries in the deep-water area of the province. Although as many as five total petroleum systems exist in the Gulf of Guinea Province, only one, the Cretaceous Composite Total Petroleum System, and its assessment unit, the Coastal Plain and Offshore Assessment Unit, had sufficient data to allow assessment. The province shows two important differences compared to the passive-margin basins south of the Niger Delta: (1) the influence of transform tectonics, and (2) the absence of evaporites and salt deformation. The province also lacks long-lived, large deltaic systems that typically result in rapid source rock burial and abundant high-quality hydrocarbon reservoirs. The USGS assessed the potential for undiscovered conventional oil and gas resources in the Gulf of Guinea Province as part of its World Petroleum Assessment 2000, estimating a mean of 1,004 million barrels of conventional undiscovered oil, 10,071 billion cubic feet of gas, and 282 million barrels of natural gas liquids. Most of the hydrocarbon potential is postulated to be in the offshore, deeper waters of the province. Gas resources may be large, as well as accessible, in areas where the zone of hydrocarbon generation is relatively shallow.
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USGS Numbered Series
Geology and total petroleum systems of the Gulf of Guinea province of West Africa