BURIAL HISTORY AND THERMAL MATURITY EVOLUTION OF THE TERMIT BASIN, NIGER

M. Harouna^1*, J. D. Pigott² and R. P. Philp²

¹ Université Abdou Moumouni, Faculté des Sciences et Techniques, Département de Géologie, B.P. 10662 Niamey, Niger.

² The University of Oklahoma, Conoco-Phillips School of Geology & Geophysics, Norman, Oklahoma, 73019 OK, USA.

^* corresponding author, email: mharounam@gmail.com

Reconstruction of the burial history and thermal evolution of the Cretaceous – Tertiary Termit Basin, a sub-basin within the larger Eastern Niger Basin of Niger, indicates spatially and temporally variable conditions for organic matter maturation during the basin’s multi-phased evolution. Three episodes of tectonic subsidence which correspond to the observed fault mechanical stratigraphy within the Termit Basin are identified: Late Cretaceous, Maastrichtian to early Paleocene, and Oligocene. These episodes fall within the regional tectonic phases of the West African Rift System delineated by previous studies. The basin exhibits substantial heterogeneity in the magnitude of the tectonic episodes and in consequent thermal maturities. For this paper, 1D burial and thermal histories of eight widely dispersed wells in the Agadem permit area in the SW of the Termit Graben were modelled to investigate the maturation of organic matter in source rocks ranging from Santonian to Oligocene in age. The kinetic modelled maturities match with maturities based on Rock-Eval Tmax values for four wells if present-day heat flows are elevated. Future exploration strategies in the Termit Basin should take into consideration these heterogeneities in thermal histories and tectonic pulses, which may lead to the development of hydrocarbon accumulations with different oil-gas compositions in different reservoir compartments.

Keywords: Termit Graben, Eastern Niger Basin, Niger, source rocks, maturity, thermal modelling.

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