Investigation of Microfacies—Electrofacies and Determination of Rock Types on the Aptian Dariyan Formation NW Persian Gulf

摘要

Dariyan (Shuaiba) Formation is one of the main reservoir units in the Persian Gulf and South Western Iran. The microfacies and depositional environment of this formation is been investigated in the current study and influencing factors in reservoir characteristics have been discussed for Dariyan reservoir in the Soroush oil field. Facies analysis conducted on core and cutting samples indicated that Dariyan Formation is mainly deposited on a carbonate ramp setting with a shallow intra shelf basin. In addition, it has been demonstrated that facies changes reflect the main controls of the tectonic and climate (sea level fluctuations) during the deposition of these sediments. To determine the reservoir unites in this formation, 5 electrofacies were determined by neural network method that it is using different petrophysical logs (i.e. GR, PHIE and SWE). Using rock typing as the best way to establish an association between the various collected data (e.g. logs and cores) and geological descriptions 4 hydraulic flow units or rock types, determined on the basis of the Flow Zone Indicator (FZI) method in the Dariyan Formation of the Soroush field. Establishing a correlation between microfacies and rock types, the carbonate zones with moderate to good reservoir properties and also the intervals with the highest reservoir quality were determined.