By Karina Smedemark
Extending the lifetime of offshore structures is a growing trend in the global energy business. Offshore operators need to ensure that platform structures have sufficient strength to carry their loads safely. Operators are usually able to extend the lifetime of their facilities according to risk- and reliability-based inspection planning, or they can opt to reinforce the structures at considerable cost. Either way, the lifetime extension process entails heavy investment.
“Today, older platforms are inspected at intervals specified by norms and best practice. But it is not possible to inspect all parts of a platform, so finding a cost-effective means of monitoring how the entire structure is doing gives us a much better basis for deciding how often to inspect and where to inspect,” says Rune Brincker, Professor and Head of Structural Integrity Research at the Danish Hydrocarbon Research and Technology Centre.
“Structural health monitoring (SHM) is a ground-breaking technology that can dramatically increase our knowledge about waves and fatigue. SHM can help scope our risk management efforts and potentially reduce operating expenditures for platforms during late field life,” Rune Brincker concludes.
Ulf Tyge Tygesen, Development Manager at Ramboll Oil & Gas, points out that SHM combines a variety of sensing technologies with an embedded measurement controller to capture, log and analyse real-time data.
“Strain gauges, accelerometers, wave radars and GPSs are mounted on the platform topsides in order to transmit real time information about the loads affecting the platform. SHM has been around for a number of years, but the really innovative thing is that we found a way of converting SHM data and feeding it into the existing finite element model of the platform. Using advanced calculations, we can determine the actual state of the structure,” he explains.