The Study of Factors Affecting Reservoir Quality of Upper Surmeh (Arab) in the Balal and Salman Oil Fields, the Persian Gulf

The Surmeh formation is hosting important oil reserves in the Middle East and Iran. It is mainly composed of dolostone in the upper part and dolomitic limestone in the lower part with interbedded anhydrite layers. According to this study, in Balal and Salman oil fields, some changes, including changes in facies, type, and the intensity of the diagenetic processes and lithology, have controlled porosity and permeability values. By comparing these factors in fields, one may conclude that dolomitic deposits in the Balal field consist mostly of barrier and lagoon facies. Toward the southeast, the proportion of grain-dominated barrier dolograinstone facies was reduced, while the dolopackstone lagoonal facies was increased. In the Salman mud-dominated tidal flat, dolowackestone and dolomudstone facies are increased but anhydrite cement content is decreased due to dolomite porosity and permeability. Comparing these two fields, they generally suggest the existence of similar facies. However, their main differences that influence the reservoir quality are the abundance of grain-dominated facies and anhydrite conten.