Trendsetter Vulcan Offshore (TVO) has delivered a tethered BOP arrangement to a deepwater rig operating in the US Gulf of Mexico, engineered to suppress wellhead fatigue in the soft seabed conditions.
This was for a recent completion project in the central Gulf region. The Hercules tethered BOP system had been developed originally to allow a deepwater floater equipped with a dynamic positioning system to work safely in shallow water.
Under the basic system configuration, four polyethylene-based tethers were anchored to suction pile foundations on the seabed, reducing BOP stack motions above the wellhead and transferring loads to the tethering system, foundations and seabed. The goals were to reduce wellhead cyclic stresses and improve fatigue life.
The soft seafloor close to the well operations location could have induced above-normal fatigue loading on the well system. TVO designed the tethering system to allow wellhead fatigue to be managed with the rig BOPs installed, helping to stabilize the well system.
As a result, operations were completed without incident.
TVO Vice President Kevin Chell said, “This project shows how making minor adjustments to our Hercules technology delivered major results, helping overcome significant technical challenges in relatively deep water.”
