Thermal maturity evolution and hydrocarbon generation in the Dibeilla oil field, Termit Basin, Eastern Niger: an organic geochemical and basin modeling approach

• Published in: Arabian journal of geosciences 2023, Vol.16 (5), Article 338
• Main Authors: Moussa, Hamma Ada, Bohari, Abdou Dodo, Ahmed, Kabir Shola, Harouna, Moussa
• Format: Article
• Language: English
• Subjects: Analytical methods; Anoxia; Basins; Cretaceous; Crude oil; Earth and Environmental Science; Earth science; Earth Sciences; Eocene; Graben; Hydrocarbons; Marine environment; Modelling; Oil; Oil and gas fields; Oil fields; Oil production; Oligocene; Organic matter; Original Paper; Paleogene; Petroleum production; Pyrolysis; Reflectance; Reservoirs; Rifting; Rock; Rocks; Tertiary
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-023-11383-4

The Termit Basin is a Cretaceous–Tertiary multi-rift graben, one of the eastern Niger basins. Belonging to this basin, the Dibeilla oil field is one of the most petroliferous oil fields in the Agadem Block. It contains multiple source rocks, but the origin of the hydrocarbons is not fully understood. The source rocks and crude oil samples from seven wells were examined using analytical techniques such as Rock–Eval pyrolysis, GC/GC–MS, vitrinite reflectance measurements, and basin modeling. Results indicate that the Upper Cretaceous (Donga and Yogou formations) and the Eocene Sokor-1 Formation have oil and gas generation potential with II/III and III type kerogens. The former were deposited in a clay-rich anoxic-suboxic marine environment with a mixture of aquatic and predominantly terrestrial organic matter and are thermally mature raching peak of oil-generation. The latter is mainly rich in terrestrial organic material deposited in a more oxic lacustrine to deltaic environment and reaches the early oil-generation stage. The Oligocene Sokor-2 Formation is oil-prone with Type I kerogens that are at an immature to marginally mature stage. The two peak values of paleo-heat (60 mW/m 2 ) are the response of the Cretaceous syn-rifting period with two phases and the Paleogene phase of the rifting cycle, which exerted a significant influence on the source rocks’ thermal maturity. The oil-source correlation reveals that oil production and preservation in the basin must extend to the deeper Campanian reservoirs. This is an important discovery that will help increasing the present-day oil production from the Eocene reservoirs of the Niger Termit Basin.