Microfacies analysis, depositional setting, and sequence stratigraphy of the Fahliyan Formation by integrating geological and petrophysical data on an oil field located in the Northwest of the Persian Gulf

Early Cretaceous Carbonates of the Fahliyan Formation are among the important reservoirs of the Persian Gulf. The findings of core description, thin section petrography, and petrophysical Gamma diagram from three key wells were used to 1) identify the facies, 2) interpret the depositional setting, and 3) analyze the sequence stratigraphy of the Fahlyian Formation. Twelve microfacies were identified and interpreted based on five categories of facies (i.e., the intertidal zone, lagoon, shoal, scattered reefs, and shallow open marine). The evidence of karstification and extensive facies alterations in the lower and upper boundaries reveal a significant unconformity in the Fahliyan Formation’s basal sequence boundary. A Gamma diagram was used to assess the efficiency of dynamic integrated prediction error filter analysis (D-INPEFA) in identifying and matching depositional sequences. By calibrating the results of the boundaries which were determined by the D-INPEFA curve with the depositional sequences determined by petrographic investigations and the descriptions of the cores, it was revealed that positive breaks (PB) generally correspond to the sequence boundaries (SB). In contrast, negative boundaries (NB) are detected in association with maximum flood surfaces (MFS). Overall, comparing depositional sequences that were segregated using the findings of petrographic studies with the D-INPEFA Gamma diagram demonstrated that interpreting the depositional sequences based on data integration can provide valuable data in comprehensive reservoir investigations from a geological standpoint.