Petrographic and petrophysical data integration for reservoir quality evaluation of the Ilam Formation in a field located in the eastern Persian Gulf

Authors

1 M. Sc., student. School of Geology, College of Science, University of Tehran, Tehran, Iran

2 Assist. Prof., School of Geology, College of Science, University of Tehran, Tehran, Iran

3 Assoc. Prof., School of Geology, College of Science, University of Tehran, Tehran, Iran

Abstract

The present study evaluates the factors controlling the reservoir quality of the Ilam Formation in one of the fields located in the eastern part of the Persian Gulf. Petrographic studies showed that the Ilam Formation in the studied field consists of eight sedimentary microfacies that were deposited in the inner, middle and outer sub-environments of a ramp-type carbonate platform, respectively. The diagenesis processes affecting this formation include micritization, cementation, bioturbation, dissolution, mechanical and chemical compression, dolomitization,, and pyritization, which occurred in marine, meteoric, and shallow to deep burial realms. Micropores visible in electron microscope images have played a significant role in increasing the storage capacity of this formation, especially in its lower part. The interpretation of sequence stratigraphy showed that the whole sequence of Ilam Formation is composed of a third-order sequence. Reservoir quality analysis based on the method of determining hydraulic flow units and Lorenz plot led to the separation of 8 flow units and 10 reservoir, baffle and barrier zones in the formation. These flow units and reservoir zones were evaluated in the framework of sequence stratigraphy and it was found that the lower part of Ilam Formation has high storage capacity and low flow capacity and can be considered as an unconventional reservoir of tight carbonate type. The middle part of this formation does not have much reservoir quality and the upper part of this formation is of high quality due to the predominance of shoal facies and the occurrence of dissolution.

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History

  • Receive Date: 19 May 2024
  • Revise Date: 27 June 2024
  • Accept Date: 30 June 2024

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