Assessment of heterogeneities of the Asmari reservoir along the Bibi Hakimeh anticline using petrophysical and sedimentological attributes: Southeast of Dezful Embayment, SW Iran

Abstract

The Asmari reservoir in the Bibi Hakimeh anticline mainly consists of carbonate rocks. This reservoir shows an evident heterogeneity across the Bibi Hakimeh structure particularly in the variation rate of oil production in different parts of the oilfield. In order to reveal reasons causing this heterogeneity and mapping distribution of such heterogeneities, different sedimentological and petrophysical approaches including hydraulic flow units (HFU) along with electro-facies (EF) analysis were employed. Accordingly, Flow Zone Indicator (FZI) and Radius 35% (R35) methods were used for HFUs determination, while Multi Resolution Graph-based Clustering (MRGC) approach was applied to classify EFs. This study indicates that although upper parts of the Asmari reservoir are dominated by muddy facies (such as mudstone and dolomudstone to wackestone), several diagenetic features particularly dolomitization and fracturing alongside dissolution contributed to increase reservoir quality effectively. These features made efficient connection between pore network and reservoir quality enhanced efficiently through increasing matrix permeability. Also, a compatible relationship between EFs and HFUs as well as pore radius classes demonstrates that changes in petrophysical attributes mainly have controlled by diagenetic features. Two sectors include NW and center parts of the oilfield show the best quality in terms of reservoir quality. This study provided a comprehensive examination to evaluate the variation of heterogeneities within the carbonate reservoir based on sedimentological and petrophysical characteristics which could be beneficial for identification of the most desirable areas of the anticline for hydrocarbon accumulation and production.