Structural Characterization and Petrophysical Evaluation of the Aradeiba and Bentiu Reservoirs in Diffra area, Muglad Basin, Sudan

This study is conducted in Diffra West Oil Field, which is located in 2B OPCO’s Block 3 exploratory area, Muglad Rift Basin. Muglad Basin is the largest sedimentary and Oil producing Basin in Sudan. The primary objective of this study is to carry out formation evaluation for hydrocarbon prospectively in Diffra West Oil Field.  Petrophysical analysis and 3D seismic interpretation were carried out to investigate the possibility of hydrocarbon accumulation in Aradeiba and Bentiu Formations. Estimated petrophysical parameters were calculated for three wells namely DW-1, HW-1 and SH-1. These parameters include volume of clay, porosity, net pay and water saturation for each well by using interactive petrophysics software (IP v. 3.5). 3D Seismic cube analysis comprised of major and minor faults picking, interpretation of Aradeiba and Bentiu horizons and time to depth conversion using Schlumberger Petrel (v. 2017) software. Petrophysical analysis has shown that the Aradeiba Formation's average clay volume ranged between 1.9% and 23%, its average porosity ranged between 12.7% and 26.6%, and its water saturation (Sw) ranged between 72.5% and 100%, with a total net pay of 23.55 m along the three wells in the study area. Whereas the Bentiu Formation showed average volumes of clay bound between 8% and 19%, average porosity (phi) between 14.8% and 21.2%, and water saturation between 69.5% and 100%, the total net pay in the Bentiu Formation across the study area is about 15.96 m. Seismic analysis and interpretation revealed that the study area consisted of normal major faults, mainly NW-SE trending in line with previous studies in Muglad Basin. Two horizons were picked and mapped, and the results of the depth conversion maps for the Aradeiba and Bentiu surfaces showed structural body dipping to the centre of the structure. Generally, in the Muglad Basin, the Bentiu Formation is considered the main reservoir while the Aradeiba Formation is the secondary reservoir; however, this study has shown that the Aradeiba in the study area has better prospectivity than the Bentiu in terms of average porosity and total net pay.