The offshore industry reported 125 incidents in 2019 involving issues with dynamic positioning systems on vessels, including some that could endanger life and production structures
International Marine Contractors Association (IMCA) said there were 125 reported DP issues during 2019, down 15% from the year before. Of these 125, 75 were reported as undesired events, 19 were DP incidents and 31 observations of DP operations issues.
IMCA technical advisor Reza Yaghoobi said at Riviera Maritime Media’s European Dynamic Positioning Conference, held on 4 February in London, the main cause of these issues was “loss of thruster and propulsion” while secondary causes were electrical issues. The most common DP operations where issues occurred was during cargo loading and unloading operations offshore.
One of the most dangerous recent DP issues involved platform supply vessel (PSV) Skansi Offshore’s Sjoborg loading and unloading cargo in Norway. It struck Equinor’s Statfjord A oil production platform in the Tampen area of the North Sea on 7 June 2019.
At the conference, Equinor principal consultant for marine operations Helge Såtendal explained the identified causes that resulted in damage to the platform from the collision and 17 delays in returning Statfjord A back into production from a planned shutdown period.
This occurred because a thruster failure and loss of DP on Sjoborg led to the prevailing weather driving the PSV on to the platform, damaging a lifeboat. “The other thrusters could not hold its position,” said Mr Såtendal. “As the PSV was on the weather side of Statfjord A, the vessel drifted into the installation.”
He said there was no alarm from the blackout safety system prior to the thruster failure, which would otherwise have given the crew time to terminate DP operations within the 500-m safety zone around the offshore platform.
Additionally, crew were inundated with alarms from the engineroom, vessel propulsion and bridge systems. Between 18 May and 7 June there were 116 prediction alarms raised on the PSV. Recommendations from subsequent accident investigations indicated there needs to be more integration on offshore support vessels of systems from separate vendors.
“There needs to be strengthening of the DP system integrator’s role during commissioning,” said Mr Såtendal. “Quality of failure mode effect analysis (FMEA) needs to be enhanced and we need to raise awareness of the importance of properly setting alarm points and having clear alarm messages,” said Mr Såtendal.
In reaction to these incidents and others, the Oil Companies International Marine Forum (OCIMF) will publish new guidelines for DP system FMEA assurance. OCIMF technical advisor Faisal Rashid said these will be available free on the OCIMF website in June 2020. “This document is still under review, but it will be like a client checklist for the offshore industry,” he said.
He stressed why energy companies were interested in improving DP operations and reducing risk. “When vessels are within the 500-m zone, oil and gas companies take on the risk and we need to know how safe the vessel is and how it is operated in the 500-m zone,” said Mr Rashid.
He welcomes more industry collaboration with associations such as IMCA.
During the conference, Nautical Institute launched its third edition of the DP Operators Handbook, which provides advice on DP principles and systems, redundancy and equipment class, operational planning and watchkeeping and operator training and competence requirements. There are also sections on position reference systems, propulsion and thrusters, power plant and DP controls.