• Pore pressure heterogeneity mapped using logs, cores, and Vp/Vs data. • Two faults govern PVT boundaries, with tectonics driving pressure variation patterns. • Lower-quality zones show higher heterogeneity due to shale content and diagenetic overprints. • Pressure correlates with secondary porosity; inversely related to acoustic impedance. • Facies change from carbonate to shale marks boundary between porous and dense zones. This study investigates the heterogeneity of pore pressure in the Lower Sarvak Formation, a key reservoir within the Dezful Embayment oil field. Utilizing petrophysical logs, core analyses, pressure measurements, PVT data, and acoustic impedance, this study provides a comprehensive analysis of pore pressure heterogeneity for the first time. A facies transition from carbonate to shale coincides with the boundary between the porous/permeable zone and the dense zone, which exhibits the highest shale content. Structural analysis identifies two faults influencing PVT boundaries, with tectonic activity contributing to pressure variations. Heterogeneity assessments reveal that lower-quality reservoir zones exhibit increased heterogeneity, likely driven by shale content, effective porosity differences, and diagenetic processes such as dolomitization and secondary porosity development. A significant correlation is observed between pore pressure and secondary porosity index, with an inverse relationship noted between pore pressure and acoustic impedance. The findings underscore the vital role of facies changes, structural features, and diagenetic phenomena in controlling pore pressure heterogeneity and pressure distribution in the formation.
Mehdipour et al. (Sun,) studied this question.