Reservoir Zonation Using Flow Zone Indicator, Electrofacies and Well Log Cumulative Standard Deviation in Dariyan Formation the Central Part of Persian Gulf

This study considers the ability of log deviation data in reservoir zonation. In this regard, 110 m of carbonate rocks from one well of the Dariyan Formation in the central part of the Persian Gulf were investigated by using 390 thin sections, well log data, and core porosity and permeability. Facies analysis led to the identification of nine microfacies in five sub-environments. To evaluate the reservoir quality in each zone, petrophysical rock types were determined by flow zone indicator and electrofacies methods. Based on the flow zone indicator, six hydraulic flow units were obtained for the reservoir interval. Using the multi-resolution graph-based clustering method and petrophysical logs of gamma, neutron, and density, 5 electrofacies were identified. Then, the two methods were compared, which show a strong correlation at many depth intervals. Zone 1 with the high frequency of electrofacies and flow units with higher reservoir quality, has the best reservoir quality. Zone 2 has low reservoir quality, flow units, and electrofacies with high gamma radiation. The frequency of high-quality reservoir electrofacies in zone 3 is lower than in zone 1. To determine reservoir zonation by the standard deviation method, each log data was subtracted from the average in the whole well and then the obtained values were added together to calculate cumulative deviation. This method is consistent with the three zones of the Dariyan Formation, but as the method of determining rock types, it is not suitable for the separation of reservoir units.