Modeling remaining CP capacity before retrofitting

Modeling remaining CP capacity before retrofitting

A comprehensive finite element cathodic protection model was developed by Deepwater for a complex comprising several structures: Platform A, Platform B, a flare support structure and associated anchor systems. Deepwater found that a full retrofit of platform B was not required if other actions were taken. 

Based on current modeling results, the following actions were recommended:

• Platform B – No retrofit was required. Continue inspections as normal.

• Platform A – No retrofit required if CP monitoring is enhanced through increased inspection frequency or fixed monitoring devices.

• Flare support structure – Was identified as the most at-risk structure across all modeled cases. A timely, minor retrofit was recommended as the structure was found to be at risk of depolarizing. Based on preliminary retrofit modeling, Deepwater recommended installation of 18 seabed-based sacrificial anode systems to maintain protection for 16 years. If the retrofit occurred after depolarization, a significantly larger anode retrofit would be required. 

Permanent, fixed CP monitoring was also recommended, as anode passivation had been observed and could worsen unpredictably. Continuous monitoring will enable timely intervention and informed model updates.