MODELING HYDROCARBON GENERATION IN ANAMBRA BASIN, SOUTHEASTERN NIGERIA: IMPLICATIONS ON HYDROCARBON PROSPECTIVITY.

The Anambra Basin contains oil and gas producing reservoirs in the southeastern part of Nigeria. Two-dimensional (2-D) modeling, using data from three (3) exploration wells has been carried out to assess the maturity, timing, and distribution of hydrocarbon generation in the Anambra Basin. This current study focuses on two sources in Anambra Basin namely; Coniacian Agwu and Nkporo source rocks. The results of models generated indicate that the onset of hydrocarbon generation from Awgu source rock started in the area of deepest subsidence during the late Campanian (77.30Ma). Awgu source rock in the model has a present-day transformation ratio of about 60-65%. This range indicates that the Awgu source rock has sufficient generation for hydrocarbon expulsion to occur. Nkporo source rock was equally observed to have capacity for hydrocarbon generation, but the generation was insufficient for expulsion because it has lower transformation ratio (<10%). Migrated hydrocarbon from the Coniacian Awgu source rock must have accumulated as oil and gas pools within the Coniacian Agbani and upper Campanian Owelli Sandstone. The discovery of gas in the Coniacian Agbani sandstone of Amansiodo-1, Akukwa-2, and Nzam-1 wells indicates the existence of petroleum traps in Cretaceous beds of the Anambra Basin. Keywords: Two dimensional modelling, Hydrocarbon generation and expulsion, Anambra basin, Transformation ratio, Awgu and Nkporo shales ,