Changes in Reservoir Quality Determined from the Diagenetic Evolution of Cretaceous Carbonates: Case Study from Sarvak and Ilam Formations in the Lurestan Area, SW Iran

In this study , the diagenetic evolution of carbonate rocks in the high zagros basin was undertaken to unravel the controls on reservoir quality . Sarvak and ilam fomations ( bangestan group) were considered as the main oil and gas reservoirs in maleh kuh and sarkan field and kuh sultan anticline, these areas are located in lurestan province in the southwest of iran. ilam formation mainly is deposited in distal open marine facies and sarvak formation has been deposited in different envirionments of a carbonate shelf system. the reservoir quality in sarvak and ilam formations are controlled by depositional texture and diagenesis. there are some diagenetic events such as compaction, cementation , phosphatization , neomorphism micritization, dolomitization and dissolution that are introduced as the diagenetic processes modifying the primary porosity and reservoir quality in these formations. the diagenetic parameters are the main factor in producing the different mictoporosity type in the formations studied via leaching and incomplete replacement of metastable carbonate crystal growth contact inhibition and endolithic boring of grains the clay minerals also affect the reservoir quality as pore filling pore lining and pore bridging in argillaceous intervals while increasing the shale percentage porosity decreases. the main diagenetic effects on grain -supported textures are cementation and dissolution. different types of cements can be observed in the sarvak and ilam formations.

کلیدواژه ها:

reservoir quality ، sarvak and ilam formations ، high zagros basin