APERM - Permeability From Production Logs

Estimation of effective permeability at the reservoir scale has been a long standing challenge in carbonate fields. The carbonate depositional and diagenetic history can be quite complex, and this can lead to a permeability field which is quite difficult to characterize. Permeability in vuggy or fractured intervals can be dramatically different from the matrix permeability measured in core plugs. However realistic estimates of oil recovery, and optimized reservoir management requires good estimates of the reservoir permeability. Accurate prediction of permeability from well logs and core plugs is notoriously difficult in carbonate reservoirs. In the Tengiz field, a giant carbonate reservoir in western Kazakhstan, a method has recently been developed to calculate apparent permeability (APERM) based on flow rate from production (PLT) logs. Incorporation of this flow calibrated apparent permeability into the static geologic earth model offers an elegant solution to the long-standing problem of how to best incorporate dynamic PLT data into a reservoir model. A reservoir model recently built using APERM resulted in a step change improvement over previous methods where only static log based permeability transforms were used to populate the earth model.