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

Katayoon Rezaeeparto,Elham Hajikazemi,Mehran Arian,Ali Kadkhodaie,Hossein Rahimpour Bonab

doi:10.4236/ojg.2016.61007

Abstract

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.

Highlights

The lower Cretaceous Orbitolina limestone of the Dariyan (Shuaiba) Formation is one of the well-known and important reservoirs in many oil fields in Southewestern Iran and the Persian Gulf [1]
Due to its importance in petroleum geology, the study of Dariyan Formation has been always considered as an area of interest for researchers whose studies have indicated the high importance of the reservoir
Sea level fall in humid climate made a carbonate ramp with marginal deltaic system extend during deposition of upper carbonates and clastics of the Dariyan Formation

Summary

Introduction

The lower Cretaceous Orbitolina limestone of the Dariyan (Shuaiba) Formation is one of the well-known and important reservoirs in many oil fields in Southewestern Iran and the Persian Gulf [1]. The name “Dariyan Formation” was taken after the section measurements of Gadvan Rocks, located in the northern parts of the Dariyan town in the Northeast of Shiraz. This lower Cretaceous formation is equal to Shuaiba, and it is among the formations of Khami group (higher Khami) with carbonate lithology. A regional unconformity, representing erosion or non-deposition of the middle Aptian section, marks the contact between Dariyan and the overlying Kazhdumi Formation in this area [2] [3]. A surface of strongly iron-stained, sandy, and glauconitic sediments is found [4]

Methods

Results

Conclusion