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 used to interpret and extrapolate the data by comparing modeling results to surface E-LogI measurements and CPET logs on specific wells.
This allows the design of the whole field to be properly carried out.
The correlation between E-LogI, CPET and 3D simulation is good
E-LogI gives optimistic values as it measures potentials at the upper part of the well
CPET may be pessimistic, because it does not allow enough time for the casing to polarize
3D simulation, based on sound polarization curves hypothesis, allows the various assumptions to be cross-checked
Reference: Cathodic Protection Modeling of Buoy Chain Connector by 3D Software Simulation: Influence of Holes Size and Coating, Marcel Roche and Jean Vittonato,TOTAL S.A.. NACE Corrosion Conference, New Orleans, 2008