Open Water/Riserless Subsea Well Intervention System

Oil and Gas Jobs

As the ageing subsea well stock continues to grow, operators are seeking more efficient intervention solutions to maximise and extend existing production. Applications which require only the delivery of fluids to a reservoir or flowline such as acid stimulation, scale squeeze, and flushing may be accommodated for using an open-water hydraulic access (OWHA) system. When in-well access is not required, an open-water downline may be deployed from a vessel, connected to a subsea access point, and used to convey fluids. For deep water applications, the use of coiled tubing as an open-water downline has emerged as the preferred solution.

A method for riserless intervention of a subsea well includes connecting an intervention assembly to a bottom hole assembly (BHA). The BHA is connected to coiled tubing. The method further includes lowering the intervention assembly to a blowout preventer (BOP) fastened to a subsea production tree using an injector of a support vessel engaged with the coiled tubing fastening the intervention assembly to the BOP slacking the coiled tubing using the vessel injector engaging a stripper of the intervention assembly with the coiled tubing and driving the BHA through the tree and into a wellbore using a subsea injector of the intervention assembly while synchronizing both injectors to maintain the slack in the coiled tubing.