THE RESERVOIR POTENTIAL OF MIOCENE CARBONATE ROCKS IN THE ASKALE AND HINIS-MUS-VAN SUB-BASINS, EAST ANATOLIA, TURKEY
*Ankara University, Faculty of Engineering, Department of Geological Engineering, 06100 Beşevler, Ankara, Turkey.
Tertiary (lower-middle Miocene) limestones in East Anatolia (eastern Turkey) are assigned to the Adilcevaz Formation. These limestones were studied using core and cuttings data from eight wells in the Tertiary Askale and Hinis-Muş-Van sub-basins, and their depositional environment, diagenetic characteristics and reservoir quality are reviewed.
The Adilcevaz Formation carbonates are up to 225m thick. Abundant bioclasts are dominated by corals, encrusting red algae, bryozoans, and benthonic and planktonic foraminifera. Reef-core, fore-reef and back-reef facies can be recognized. The preservation of primary porosity is generally poor as a result of late calcite cementation. Porosity is mainly present as moulds, vugs and interparticle types, which are best developed in the fore-reef and reef-core facies. However these pores are poorly connected and permeability is generally less than 0.1mD. In contrast to coeval limestones of similiar facies in Iran, Iraq and other parts of the Middle East, the Adilcevaz Formation has little reservoir potential.