In October 2020, Norwegian operator OKEA approached Oceaneering seeking a solution to address four stuck actuators located on subsea trees at the Draugen field.
The actuators, located in water depths of 300 m, were locked in an open position, prohibiting regular operations, and the cause was unknown.
Failing to return the valves to normal operation could have resulted in OKEA having to pull the tree.
OKEA wanted to resume full production as soon as possible, resulting in a very tight schedule for the ROV-operated tooling development.
Oceaneering worked closely with the client and used schematics of the stuck actuators to develop potential repair solutions.
Tooling suite under development and testing.
Several concepts for valve operation, using new and existing tools, were developed in parallel to ensure the operation was completed with minimum risk.
Engineers used 3D modelling software and extensive in-house 3D printing capabilities to develop and evaluate viable solutions.
After narrowing the concept pool to a bespoke project-specific tooling suite, Oceaneering used a combination of in-house machining and a network of local suppliers to ensure all necessary parts could be manufactured within the project schedule. The suite included a simple stem gripper tool and additional redundancy in the form of bespoke drill and tap tools.
Rigorous testing was also completed at Oceaneering’s facilities in Stavanger. A test stand identical to the tree at Draugen was used to vet the tooling, enabling engineers to refine designs and make improvements that ensured proper operation once deployed. Originally designed to pull a minimum of one ton, the stem gripper tool overachieved during testing operations, pulling up to 15 ton.
All testing activities were video recorded so remotely operated vehicle (ROV) pilots could later familiarize themselves with the tools. Adding additional complexity to the project was the ongoing Coronavirus pandemic which limited in-person interaction. The ability to live-stream testing activities and hold regular virtual meetings enabled collaboration and essential communications between OKEA and the Oceaneering team.
The tools were deployed to site in January 2021.
Successful remote actuation after tool gripper released stuck valve.
The stem gripper tool was successful, eliminating the need to use the back-up tools. OKEA was able to save five days’ time of the offshore operations schedule and, most importantly, the tree did not need to be pulled. Pulling the tree would have resulted in a year's lost production. Since their initial use in early 2021, the stem pulling tool has been successfully used for the same purpose, reconfirming their fitness for purpose, and maintaining production for OKEA.
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