Nazanin Vakili - Department of Geology, Shiraz branch, Islamic Azad University, Shiraz, Iran
Ali Paknejadyan - Department of Geology, Shiraz branch, Islamic Azad University, Shiraz, Iran
Kourosh Yazdjerdi - Department of Geology, Shiraz branch, Islamic Azad University, Shiraz, Iran
Seyed Saeed Mousapoor mousavi

This research studies a subterraneous section of the Dalan Formation in well X in one of the Persian Gulfgas field.The Dalan Formation age is permian, it locates in folded Zagros region and the Persian Gulfcontains giant gas resources. The lower boundary of the Dalan Formation is continuous and gradual, alongwith the siliciclastics of Faraghun Formation. The Upper Dalan is overlain by the Kangan Formation. Theboundary of these Formations is the Permian-Triassic erosional surface. Diagenesis processes that affectedthe Dalan Formation include Cementation, Bioturbation, Micritization, Geopetal fabric, Dissolution,Compaction, Neomorphism, Pyritization, Ironzation and Dolomitization. dolomitization, dissolution andcementation are the predominant diagenetic processes in this formation. Marine, Meteoric and Burialdiagenetic environments affected the Dalan Formation. According to sedimentary structure, texture andbiota content ۱۶ microfacies were determined for the Dalan Formation. These microfacies are presented in ۳facies belts, including Tidal flats, Lagoon and Carbonate shoal. The sedimentary environment of the DalanFormation is introduced as a homoclinal carbonate ramp deposition. Dissolution along with microfractureshad a positive effect on the improvement of reservoir quality.

Microfacies, Sedimentary environment, Reservoir quality, Lower Dalan Formation, Gas Field