Abstract:

The Termit Basin, which is located in the southeastern Niger and tectonically belongs to the northern part of West African Rift System (WARS), is a MesozoicCenozoic rift basin developed on the PrecambrianJurassic basement. Since 1974, many foreign oil companies have made exploration in Termit Basin and found seven reservoirs in Dinga Faulted Terrace. CNPC began exploration in the basin in 2008. It is a very difficult issue that how to evaluate the potential and find abundant petroleum. Based on the tectonic evolution of the Late Cretaceous great transgression and two rifts superimposition, this study mainly focuses on analyzing the main controlling factors of Paleogene hydrocarbon accumulation. The petroleum accumulation model of the Paleogene shows the following six characteristics: (1) hydrocarbon generation is controlled by the large area of marine source rocks; (2) sandstone distribution is influenced by superimposition of two phases rifting; (3) secondary migration of oil and gas is controlled by faults and thick carrier beds; (4) fluid potential is decided by structural relief; (5) petroleum accumulation is determined by the relationship between faults and sandstone; (6) preservation of oil and gas is defined by cap rocks and lateral blockages. The analysis of main controlling factors reveals the petroleum accumulation principles of the Paleogene, and facilitates the exploration of the Termit Basin.

Key words: West African Rift System, Termit Basin, great transgression, superimposition of two phases rifting, tectonic evolution, main controlling factors of hydrocarbon accumulation