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

To investigate the microfossils, microfacies, depositional environment, and diagenetic processes with in the Ilam Formation in Abadan Plain, Well Yadman-۱ was studied. This research involved the study of ۴۴۰ 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 ۱۰ distinct microfacies, which could be classified into ۴ 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 ۳۰ and ۲۶ Wynd, the age of the Ilam Formation has been determined.

کلیدواژه ها:

Abadan Plain ، Diagenesis ، Ilam Formation ، Sedimentary environment ، Zagros