As technology and the economics of offshore fields continue to change there is the increasing need to keep ageing infrastructure functional and safe increasingly longer service lives. This places demands on the operators and regulating agencies to continue to provide assurances that the structural integrity of offshore facilities can be maintained for considerable periods greater than the original design lives. Corrosion and fatigue needs to be reassessed and in many cases there is the need for some form of mitigation to achieve the extended life. Mitigation options will range from enhanced monitoring to structural retrofit and frequently this needs to be done while the facility remains on station and in production. For some complex deep water facilities such as tension-leg platforms, life extension will present significant challenges as the new frontiers of technology need to be explored and proven to maintain the integrity of critical systems. For ship-conversion facilities such as FPSOs and FSOs the practical solutions to rehabilitating strength while the facility remains on station and operating requires non-conventional approaches. Traditionally ship repairs are undertaken in ship yards and dry docks where there is unlimited labor and access to heavy weight machinery such as dockside cranes. Performing the work offshore severely limits the numbers of personnel and does not have the use of heavy lifting equipment. The presence of hydrocarbons also presents safe working restrictions that need to be integral to the work program.
This paper will discuss proven innovative solutions for rehabilitating floating structures while on-station to allow service lives to be extended safely. This includes creative mitigation solutions that are available to assure strength and fatigue management. While there are many challenges to face in these programs the benefits to the operator are substantial because of the minimization of the loss of production what would normally result from removing the critical infrastructure from the field for the prolonged repair program duration.
