Cathodic protection upgrade of the 1,050 ft water depth Cognac platform

This paper reports the steps of a cathodic protection upgrade of a three year old deep water platform (the Cognac structure, Mississippi Canyon 194A) installed in 1977/78. These steps include obtaining results from an ROV survey, using the survey data to calculate added currents needed to upgrade cathodic protection of the platform, achieving retrofit anode installation using then novel methods, and following-up with CP surveys showing the success of the upgrade. The authors calculated that 3,100 amperes of additional current applied at depths from 250 to 1,050 feet would be needed to achieve full cathodic protection of the well conductors and jacket of Cognac. Approximately 1,100 additional aluminum anodes were installed during the early 1980`s, using two novel installation methods. Installed cost was estimated at $5.4MM. Potentials since the time of the upgrade have been very satisfactory.