In cathodic protection of deep well casings, current requirement is often based on surface E-LogI
measurements. This can be advantageously completed by Corrosion Protection Evaluation Tool
(CPET) logs. Nonetheless, those logs cannot be performed on every well when large fields of
hundreds of wells need to be protected. 3D simulation is consequently of main interest in this situation:
by comparing modeling results to surface E-LogI measurements and CPET logs on specific wells. It
allows the design of the whole field to be properly carried out. This study presents what has been
performed in this way for Qatar Petroleum at the Dukhan field.