Petrophysical evaluation and permeability prediction in the Sarvak reservoir formation using Lucia method in an oilfield of the Abadan Plain, SW Iran

Accurate permeability prediction in heterogeneous carbonate reservoirs remains one of the challenges in petrophysical evaluation due to rock-fabric variability and the pervasive influence of diagenetic processes. Therefore, assessing the accuracy of rock-fabric-based methods and benchmarking them against other conventional approaches plays an essential role in characterizing reservoir quality and reducing uncertainty in reservoir modeling. In this study, the Sarvak Formation in an oilfield located in the Abadan Plain, southwest Iran, was evaluated using core descriptions, thin-section petrography, core porosity–permeability measurements, and wireline logs. To assess reservoir quality and predict permeability, Lucia’s rock-fabric method was applied, and its performance was compared with the Hydraulic Flow Unit (HFU) and Winland (R35) pore-throat size classification approaches. Furthermore, reservoir rock types (RRTs) were identified, and Lucia-predicted permeability values were systematically compared with core-measured data. The results led to the identification of five distinct reservoir rock types exhibiting contrasting storage capacities and fluid flow behaviors. Comparing the predicted and measured permeabilities delineated eight intervals, comprising four zones with good agreement (R2=0.73) and four zones with poor agreement (R2=0.26). The highest degree of correlation was observed in intervals where fluid flow behavior was predominantly governed by rock fabric and interparticle/intercrystalline pore networks. Conversely, reservoir heterogeneities induced by dolomitization, recrystallization, fracturing, and the development of isolated (separate) secondary porosity degraded the prediction accuracy in the remaining zones. Overall, the findings demonstrate that integrating sedimentological, petrographic, and petrophysical data provides a robust and effective framework for deciphering reservoir heterogeneity and evaluating reservoir quality in the Sarvak Formation.