Journal of Petroleum Research

Journal of Petroleum Research

Rock Facies Classification Using Hydraulic Flow Units and Electrofacies: A Case Study of the Fahliyan Reservoir in One of the Fields of Abadan Plain

Document Type : Research Paper

Authors
1 Earth Sciences, Kharazmi University, Tehran
2 Earth Sciences-, Kharazmi University
10.22078/pr.2026.5769.3575
Abstract
The Fahliyan Formation is recognized as one of the major hydrocarbon reservoirs in the Zagros Basin and the Persian Gulf, mainly composed of carbonate sequences and exhibiting considerable complexity in terms of reservoir characteristics. Rock typing is a key step in petrophysical and geological reservoir studies, as it contributes to a better understanding of reservoir behavior, quality, and fluid flow prediction. In this study, an integrated approach using the Flow Zone Indicator (FZI) method, electrofacies clustering, and microscopic facies analysis has yielded reliable results for rock type determination. In the first step, six microfacies belonging to a ramp setting (including lagoon and shoal deposits) were identified from thin sections of well A2. Subsequently, using the FZI method, four hydraulic flow units were defined based on porosity and permeability data from the Fahliyan reservoir in well A2. By integrating petrographic and petrophysical data, reservoir quality was ranked from very poor (RT1) to good (RT4) based on the four identified flow units. Then, using data from three petrophysical logs (effective porosity, neutron, and sonic), electrofacies of the Fahliyan Formation were determined using the MRGC clustering method, resulting in the identification of 11 electrofacies. The combination of sedimentary facies, electrofacies, and rock typing indicates that the blue electrofacies (RT4, MF6) represents good reservoir quality, whereas the red electrofacies (RT1, MF1, MF2) represents very poor reservoir quality. This integrated approach provides an effective framework for zoning and ranking reservoir quality in heterogeneous carbonate reservoirs such as the Fahliyan Formation.
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