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

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 rese rvoirs 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 c aused to de crease of brittle property and this condition had investigated by petrophysical evaluation. Ac cording 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 satura tion 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.