Impact of Microfacies, Sedimentary Environment, and Diagenesis on the Reservoir Quality of Ilam Formation in Yadman Field

Articles in Press

Document Type : Original Research Article

Authors

Department of Sedimentary Basin and Petroleum, Faculty of Earth Science, Shahid Beheshti University, Tehran, Iran

Abstract

To investigate the microfossils, microfacies, depositional environment, and diagenetic processes with in the Ilam Formation in Abadan Plain, Well Yadman-1 was studied. This research involved the study of 440 microscopic thin sections obtained from both core and cutting samples. The classification of carbonate rocks followed Dunham's method, microfacies were identified using Fluegel and Wilson's approach, and porosity was defined based on Choquette and Perry's classification. The microfacies analysis unveiled the existence of 10 distinct microfacies, which could be classified into 4 microfacies belts corresponding to shoal, mid-ramp, outer ramp, and basin environments. Notably, the studied facies exhibited a gradual transition and were devoid of reef facies, turbidite deposits, reworked carbonates, slumped and slid facies, oncoides, cortoids, and aggregate grains. These characteristics indicate the deposition of the Ilam Formation on a carbonate ramp of the single slope (homocline) type. Furthermore, various diagenetic processes were identified within the Ilam Formation, including dissolution, cementation, dolomitization, stylolite, pyritization, compaction, and fracturing. Based on the identified microfossils in the framework of two biozones with Santonian ages, zones 30 and 26 Wynd, the age of the Ilam Formation has been determined.

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Sustainable Earth Trends

Articles in Press, Accepted Manuscript
Available Online from 12 May 2025

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