Effect Of Diagenetic Processes on Reservoir Quality of Asmari Formation (With an Emphasis on the Sandstone Member) in the Northern Flank of the Aghajari Oil Field

Asmari Formation (Oligocene-Miocene) is one of the most important reservoir in the Aghajari oil field in the Dezful Embayment in south west of Iran which is composed of limestone, dolomite and sandstone units. The purpose of this study is to identify, differentiate and interpret the diagenetic processes and their impact on the reservoir quality of the Asmari Formation in wells 64, 30 and 149 of Aghajari oil field. The most important diagenetic processes that affected the Asmari Formation include dissolution, compaction, fracturing, dolomitization, cementation and anhydritization. Processes such as dissolution (by creating vuggy and moldic porosity), fracturing and dolomitization increase the reservoir quality while and processes such as anhydritization, compaction and cementation reduced the reservoir quality in zone of 3 and 4. Also one of the reasons for increasing the reservoir quality of Asmari Formation is the present of sandstone units in the Dezful Embayment. These increases in reservoir quality can be related to sorting and rounding of grain size, geometry and distribution of sandstone in this oil field. These processes led to creation of the best reservoir quality in quartzarenite and limy sandstones facies. Finally, zone 3 has a better reservoir quality than zone 4 that it is due to impact of diagenetic processes as well as increases sandstones thickness.