Controls of depositional facies on porosity–permeability distribution in the Upper Dalan and Kangan formations in a field in the eastern Persian Gulf

Authors

1 School of Geology, College of Science, University of Tehran

2 University of Tehran

Abstract

The Permian-Triassic sedimentary sequences in the Persian Gulf host some of the world's largest gas reserves. The distribution of reservoir properties in these reservoirs is significantly controlled by sedimentary (primary) factors such as textural, lithological, and facies variations. This study, by integrating various petrographic data from core samples and thin sections, along with porosity and permeability data obtained from core analyses of a well in one of the eastern fields of the Persian Gulf, aims to evaluate the control of these factors on the distribution of porosity and permeability in reservoir units K1 to K3 of the Upper Dalan and Kangan formations. Facies analysis led to the identification of 13 microfacies, which grouped into five facies belts, representing a homoclinal ramp-type carbonate platform. The analysis of sedimentary textures, lithological variations, and sedimentary microfacies from the perspective of porosity and permeability distribution data indicates a close correlation between them. A significant portion of these correlations is due to the preservation of reservoir potential in the facies, and many diagenetic processes are directly or indirectly influenced by textural and facies characteristics. Dolomitic or dolomite-bearing rocks with shoal facies, which made up about half of the studied sequences, exhibit the best reservoir quality. Grain-supported grainstone facies containing ooids, peloids, and skeletal fragments from the back-shoal environment show the best porosity, with intergranular and moldic pores being the dominant types in these facies. The highest permeability is associated with mud-supported dolomudstone facies, where intercrystalline pores are the dominant type.

Keywords

Applied Sedimentology

Articles in Press, Accepted Manuscript
Available Online from 08 December 2024

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History

  • Receive Date: 23 October 2024
  • Revise Date: 05 December 2024
  • Accept Date: 08 December 2024

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