Pore type pathways to hydrocarbon potential: electrical resistivity in Permian–Triassic Persian Gulf carbonates

Electrical resistivity plays a key role in evaluating fluid saturation, production potential, and development of hydrocarbon reservoirs. This study investigates the impact of different pore types on electrical resistivity by utilizing porosity data and calculated water saturation in the Dalan and Kangan carbonate-evaporite formations of the central Persian Gulf. The lithology, pore types, facies, and diagenetic processes of these formations were determined through microscopic studies of 1367 thin sections. The porosities of 1204 samples were measured. Subsequently, water saturation was calculated using the Archie equation based on well log and laboratory data from 342.92 m of cores. Porosity was found to be a critical factor in determining electrical resistivity. Diagenetic processes that increased porosity and created various pore types, such as dolomitization and dissolution, led to a decrease in electrical resistivity. In contrast, anhydrite cementation reduces porosity. Therefore, there is a clear positive correlation between anhydrite content and resistivity. Anhydrite occludes the pore throats and inhibits current flow through the pores. This process has a significant impact on electrical resistivity, compared to other lithologies, facies, and diagenetic processes. In conclusion, this study demonstrates that porosity, water saturation, and pore type are critical factors influencing electrical resistivity in carbonate reservoirs. Diagenetic processes, particularly anhydrite cementation and pore-filling, further impact resistivity by altering pore structures and reducing conductivity. These findings highlight the complex interplay between geological and petrophysical parameters in assessing hydrocarbon reservoir potential.