InterMoor has completed the final tensioning and chain-cutting operations on the Turritella FPSO vessel for Shell’s Stones (32/22) project, located in the Walker Ridge protraction area in the Gulf of Mexico (GoM).

The Turritella will connect to subsea infrastructure in about 2,896 m of water, breaking the existing water depth record for an oil and gas production facility.

The ultradeepwater project marks the first FPSO unit for Shell in the GoM, and the second FPSO unit in the GoM after Cascade/Chinook (32/20).

The Turritella, which arrived in January, is a disconnectable turret moored FPSO unit with nine mooring lines consisting of chain and polyester, arrayed in three bundles of three.

The mooring lines were attached to a disconnectable buoyant turret mooring (BTM) buoy at the field, awaiting the FPSO unit’s arrival.

Each mooring leg has an in-line mooring connector (ILMC) tensioning system, located about 274 m below the surface, which was pretensioned after connection to the BTM. Once the Turritella arrived, and the BTM was recovered by the FPSO unit.

InterMoor’s workscope consisted of chain final tension adjustments through the ILMC system, subsequent cut and removal of excess chain, and riser pull-in rope stretching and transfer to the FPSO unit.

InterMoor used the Seacor Keith Cowan anchor-handling vessel to perform the first phase of the operations and later moved to a larger construction vessel already on charter and on standby.

Offshore