The technology, suited to shallow-water depths of up to 150 m (492 ft), combines Aquaterra’s HP/HT riser system and Plexus’ POS-GRIP wellhead system.
An inner riser string installed inside a conventional high-pressure riser (HPR), which spans the gap between a dry surface BOP and a wet subsea tree, provides 20,000 psi (1,379 bar) capability, with all metal-to-metal gas tight seals on both the external and internal riser string.
The arrangement is also claimed to eliminate issues associated with surface wellheads containing elastomeric seals, particularly those located between the mudline and surface.
Ben Cannell of Aquaterra said the system has “the potential to change the industry’s default position of selecting semisubmersible rigs for developments in water depths up to 150 m (492 ft), which today make-up over 60% of all subsea developments worldwide.
“It renders the use of jackup rigs in such scenarios both feasible and attractive in both a technical and commercial context.
“The dual-barrier HP/HT riser system facilitates safe and effective drilling operations in HP/HT conditions and provides a structurally sound, pressure-retaining conduit between the subsea wellhead/tree and the rig’s surface BOP.”