An Integrated Approach for the Assessment of Hydrocarbon Potential in Carbonate Reservoirs: Potwar Plateau, Pakistan

Abstract

The Potwar Plateau region of the Upper Indus Basin in Pakistan is known for its complex carbonate reservoirs, which pose significant challenges for hydrocarbon exploration and production. The integrated reservoir simulation study can help mitigate these challenges by better understanding the reservoir behavior and optimizing production strategies. The reservoir characterization of this region has essential importance in Pakistan because tight limestone and fractures (with vugs and leached features) may provide a zone of high porosity, permeability, and reservoir properties with isolated distribution in tight carbonates. The seismic and well log data were integrated to get the reservoir characterization and mark targeted reservoirs (Chorgali and Sakesar Formations) in Balkassar Oil Field. The study utilized 3D seismic interpretation, petrophysics analysis, rock physics analysis, and seismic inversion techniques to evaluate the subsurface properties of the carbonate reservoir. The time grid and depth contour map generation for Chorgali and Sakesar Formations show less time, about 1.2–1.3 s for Chorgali and 1.32–1.488 s for Sakesar which reveal clearly that the central part between the two faults is a shallow portion which is the crest of Balkassar anticline forming the suitable structural trap for hydrocarbon accumulation. Three reservoir zones with certain depths are marked based on petrophysics and rock physics analysis. The cross‐plot between mu–rho versus lambda–rho value indicates a high porosity value at 2,460–2,580 m. From seismic inversion, low impedance values are observed in that reservoir zone (2,400–2,500 m).