Prospect evaluation of the Paleogene Sokor-1 reservoirs in Fana Field, Termit Basin (Niger Republic) using geophysical well logs and sedimentological data

Abstract

The present study evaluated the Paleogene Sokor-1 clastic reservoirs in the Fana Field on the Agadem Block, Termit Basin, Niger Republic. The evaluation of the hydrocarbon prospect of the Field, which involved petrophysical analysis of six wells namely Fana_2, Fana E_1, Fana N_2, Fana W_1, Fana S_1, Fana SW_1, and sidewall core sample description of Fana_2 well. The petrophysical interpretation of the well-log data was carried out using Interactive Petrophysics software. The petrophysical properties of the hydrocarbon-bearing reservoirs were rated to be suitable reservoirs with average effective porosities varying from 25.8 to 31.6%, permeability varying from 123.6 to 427.7 mD, average water saturation values ranging from 15.2 to 33.0%, and the average range of hydrocarbon saturation is 67.0 to 84.8%. The values of volume of shale (V_sh) of the identified reservoirs indicated that the reservoirs are generally shaly to a high shale/clayey content. The dia-porosity and M-N cross plots revealed that the reservoirs of the Sokor-1 Formation are predominantly sandstone with shale/clay intercalations. The shale structural behaviour of the reservoirs revealed that the dominant shale was mainly dispersed and laminated shale volumes that could impact on the reservoir qualities. The spatial variations of petrophysical parameters indicated that lower ^N/_G values favour the northeast and southern part of the map while the south area has a higher average effective porosity value. This study identified the southern part of the Fana Field as the most prospective and should be considered for the future exploration and development of the Fana field.