Investigation of Reservoir Properties, Sedimentary Environment, and Reservoir Modeling of Sarvak Reservoir Formation in a Southwestern Iranian Oil Field

Abstract The Late Albian-Early Cenomanian Sarvak Formation is a significant oil reservoir in the Zagros region of southwestern Iran. This study examines the reservoir characteristics, sedimentary environment, and modeling of the Sarvak Formation using seismic data from an Iranian field. A total of 11 facies were identified based on allocomes and orthocomes, indicating deposition in a homoclinal ramp environment across four sub-environments: outer ramp, middle ramp, and inner ramp. The reservoir quality of the Sarvak Formation is primarily influenced by sedimentary facies and diagenesis processes, which include bioturbation, micritization, chemical and mechanical compression, cementation, neomorphism, dissolution, porosity, dolomitization, and fracturing across marine, meteoric, and burial environments. Additionally, four discontinuities—Lower Cenomanian, Middle Cenomanian, Cenomanian-Turonian boundary, and Middle Turonian discontinuity—were identified based on ancient soil, shearing, meteoric porosity, and karstization. This study recognizes four sedimentary sequences: the Albian Barian-Lower Cenomanian, Middle Cenomanian, Barian Cenomanian, and Lower to Middle Turonian. All sequence boundaries are classified as SB1, except for the lower boundary of the first sequence, which is SB2. The TST sections of the first and second sequences show low reservoir quality, while the third and fourth TST sequences exhibit good to excellent reservoir quality due to supporting grain rudist facies. The third and fourth HST sequences provide the best reservoir quality in this formation. Under the discontinuities, meteorically influenced diagenesis processes have significantly increased mold porosity and extensive dissolution features.