Sedimentary environment and microfacies of Sarvak Formation, Zone 3 in South Azadegan field

Subject Areas : Earth Sciences

sara maleki kheymehsari ^{1 *} , Hosein Lotfiyan Zadeh ²

1 - Department of Geology,Be.C.,Islamic Azad University,Behbahan,Iran
2 - Department of Geology,Be.C.,Islamic Azad University,Behbahan,Iran

Received: 2025-08-28 Accepted : 2025-09-30 Published : 2025-10-19

Keywords: Microfacies, Depositional environment, Sarvak Formation, South Azadegan oil field,

Abstract :

Abstract

 

In order to study the Sarvak Formation in Zone 3 of the South Azadegan oil field in the Abadan Plain, 10 cores and 50 thin sections prepared from drilled cores were examined. Petrographic analysis led to the identification of seven depositional microfacies. These include lagoonal facies such as miliolid wackestone and benthic foraminifera-bearing packstone/wackestone; barrier facies including benthic foraminifera- and peloid-bearing grainstone, rudist boundstone, and rudist packstone; and open marine facies including pelagic foraminifera (oligosteginid) wackestone and bioclastic echinoid packstone. Based on faunal assemblages, the presence of micrite in the sedimentary fabric of most facies, the occurrence of lagoonal, barrier, and open marine facies, and their gradual facies transitions, the depositional model of the Sarvak Formation in Zone 3 of the South Azadegan field has been interpreted as a shallow-water carbonate platform of a homoclinal ramp type. The reservoir quality of the Sarvak Formation is closely related to diagenetic processes. Cementation and compaction are the main processes reducing reservoir quality, whereas dissolution, vuggy porosity, fracture-related porosity, and dolomitization enhance it. Lagoonal mud-supported facies, due to dissolution and fracturing, exhibit better reservoir properties. Understanding the role of diagenetic processes in reservoir rocks can significantly contribute to evaluating the reservoir quality of the Sarvak Formation in the South Azadegan field.

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