Geophysical modeling and reservoir performance of Aouinet Wanin F3B sandstone in well A37 NC 169A, Wafa Field, Ghadamis Basin, Libya

Abstract

This study focuses on evaluating the quality of the Aouinet Wanin F3B sandstone as a potential hydrocarbon reservoir in Well A37, NC 169A, Wafa Field, Ghadamis Basin, northwest Libya. Capillary pressure data, a key indicator of pore throat size distribution and fluid percolation capability, is crucial for reservoir characterization. However, due to the high costs, time constraints, and environmental concerns associated with mercury injection capillary pressure testing, this study introduces an alternative approach. We utilize routine core analysis data specifically porosity and permeability to model synthetic drainage capillary pressure curves based on Pittman’s modified equations. Our results reveal three distinct rock types represent the reservoir intervals, categorized into mega-, macro-, and micro-pores. The uppermost zone of mega- and macro-pores demonstrates excellent to good reservoir qualities. The log–log plot of pore throat radius versus permeability using Pittman’s R50 equation yielded a 1 mD permeability cutoff, aligning with common reservoir benchmarks, while the Winland R35 equation produced a cutoff of 0.4 mD, slightly outside the acceptable range which is between 0.5 and 1 mD. These findings offer a cost-effective and reliable alternative for reservoir quality assessment.