Installation and retrieval of 10,000psi rated full bore riser

Paul Boughton

Aquaterra Energy has successfully completed the first installation and retrieval of a 10,000psi rated, 25” OD full bore riser for Apache North Sea.

Apache North Sea required a high pressure riser system to allow three subsea wells to be drilled safely on the Bacchus field from the Rowan Gorilla VII. Building on the success of Aquaterra Energy’s 5,000psi riser system, the team developed a 10,000psi system, in collaboration with Oil States Industries, using its Merlin connectors. Merlin connectors have never before been used at such a high pressure in such a large size for this application and the completion of this project therefore marks the first riser system of this kind to be run worldwide.

As well as supplying the full bore drilling riser, a subsea connector, installation equipment with surface tensioning and a complete fatigue monitoring system were also supplied. Aquaterra Energy’s dedicated in-house team of drilling riser engineers provided design engineering, project management, operational expertise and managed the delivery of the riser system.

The equipment for Apache North Sea was mobilised in August 2011 and arrived back at Aquaterra Energy’s warehouse at the end of July 2012. During this time the full riser system had been successfully run and pulled eight times, including jumping between the first well (East) and second well (West).

Following successful conclusion of the first two wells, Apache North Sea decided to revisit the Bacchus field, 7km east of the Forties Alpha platform, to complete a third well, Bacchus Far West (B1). Aquaterra Energy was appointed to conduct a comprehensive maintenance programme on the 10k riser system and work with Apache North Sea to reinstall the system onto the third well, with the use of the Rowan Gorilla VII. The maintenance programme was completed within a tight schedule and on 5th April 2013 the riser was successfully run and landed on the third well, Bacchus Far West (B1).