HYDROCARBON ACCUMULATION CHARACTERISTICS AND CONTROLLING FACTORS IN EAST AND WEST CONTINENTAL MARGINS OF AFRICA: TAKING RUVUMA BASIN AND NIGER DELTA BASIN AS EXAMPLES

The African continental margin is one of the major hydrocarbon producing areas now in the world. However, most of the hydrocarbon resources are found on the west margin of the continent and no giant oil fields have been discovered on the east continental margin up to now. Based on the comparative study of tectonic evolution and hydrocarbon accumulation conditions between the east and west continental margins, such as source rocks, reservoirs, cap rocks and structural traps in the Ruvuma Basin and the Niger Delta Basin, we discussed the major controlling factors for hydrocarbon accumulation in the two typical basins. As we know, the east and west sides of the Africa continent are respectively related to different plates. The difference in forming time and tectonic evolution between the east and west leads to the differentiation of hydrocarbon accumulation. The west continental margin of Africa owes its highly hydrocarbon potential to the excellent source-reservoir-seal assemblages, while the east margin is lack of high-quality source rocks. The multiphase volcanic activities might have destroyed the existed traps. The comparison of the east and west margins of Africa told us that the rich oil and gas on the west continental margin are from the assemblage of high-quality source rocks, the local cap of saline sequences and the traps formed by salt structures. The deepwater off the Zambezi Delta could be a target for future exploration.