Petrophysical Evaluation and the Effect of Shale Layers on Net Pay Zone Thickness in the Marun Oil Field, Iran

Saeed Tajali,Mehran Arian

doi:10.4236/ojg.2016.68059

Abstract

The Marun oil field is situated on the eastern part of Zagros, Iran. Aghajari Formation is cropping out on the surface. The Asmari formation, the Bangestan and Khami Groups are the Main reservoirs in this field and Asmari formation is the most important reservoir. Dolomitic carbonates are dominant lithology in the study well. Increasing of shale Layers in different layers caused to decrease of brittle property and this condition had investigated by petrophysical evaluation. According to this research, near to 29 percent shale has mixed with sandstone rock units in the study well which is comparable with maximum porosity there. Because, sandstone layers have shown the best porosity (near to 26 percent) in the study well. Also, good rocks based on water saturation and porosity are situated in sandstone units and poor rocks have existed in the limestone-dolomites. Therefore, facies changes in the Asmari formation can explain the observed variations in reservoir quality in the study area.

Highlights

The Marun oil field has located in the south east of Ahwaz city on the south west of Iran
Arian to its importance in petroleum geology, the study of Asmari formation has been always considered as an area of interest for many researchers
The ρ f is the density of the fluid saturating the rock immediately surrounding the borehole and it can be show by below formula no. 1 [10]; ( ) φ = ρma − ρ f

Summary

Introduction

The Marun oil field has located in the south east of Ahwaz city on the south west of Iran. It has got 65 Km length and 8 Km width on the Zagros fold-and-thrust belt. The Oligocene-lower Miocene [1]-[4] limestones and sandstone of the Asmari formation are the most important reservoirs in Iran. Arian to its importance in petroleum geology, the study of Asmari formation has been always considered as an area of interest for many researchers. Two major fractures system in the Marun oil field could be recognized which are regional fractures (with east-west trending) and local fractures (fold and bending related fractures). The results of Iso-permeability, RFT, PI maps are consisted with the results of fracture study in order to identify fractured sectors in the Marun Anticline

Location

Geology Setting

Materials and Methods

Results and Discussion

Conclusions