Reservoir Facies Controlling Factors in the Upper Permian Dalan Formation, Southwest Iran

The Upper Permian Dalan Formation is an economically significant gas and condensate reservoir in the Fars region of southwest Iran. It is composed mainly of limestone and dolostone. Facies analyses, depositional environments and diagenetic processes of the Dalan Formation in eight wells and the reference section at the Surmeh Anticline were studied. Field and petrographic studies combined with wire-line well-logs analyses and available seismic images resulted in recognition of various carbonate facies related to tidal flat, lagoon, shoal, basinal facies tracts, siliciclastic and evaporitic facies deposited on a carbonate ramp.