New Helical Riser Buoyancy Part of Diamond Strategy on Efficiency

Diamond Offshore Drilling Inc.’s proprietary Helical Buoyancy design – which will be utilized in the drill riser buoyancy module (DRBM) that Diamond and Trelleborg will jointly develop, manufacture and market – will combat the effects of offshore loop currents in a way that boosts riser deployment speed, according to an Evercore-ISI research note.

Violent loop currents – which make it more difficult to position and centralize marine drilling risers -- are found in virtually every deepwater environment. But these currents pose particular challenges in the U.S. Gulf of Mexico and at the mouth of the Amazon River offshore Brazil due to the magnitude of these currents, which induce lateral drag on the riser and push the drill string out of place, explained James West, senior managing director and partner with Evercore’s oil services, equipment and drilling fundamental research group, in the June 13 research note.

The design was developed by Diamond after years of testing using computational fluid dynamics and high Reynolds Number Wind Tunnel testing. The companies will work together on further application engineering, data acquisition, testing and development of Helical Buoyancy applications across the offshore drilling market.

The design’s axial helical grooves built into the riser pipe disrupts the fluid flows that cause lateral drag and vortex-induced vibration, without the need to add modular riser equipment below the rig floor. This offers benefits from both a personnel safety and riser deployment speed perspective, James West said in a June 13 note.

As part of the agreement, Diamond has ordered from Trelleborg DRBMs for its sixth-generation drillships Ocean BlackRhino (UDW drillship) and Ocean BlackLion (UDW drillship). The design will allow these rigs to run their risers about 20 percent faster than traditional bearings/little wings buoyancy modules, West stated. Both rigs currently are under contract in a high-current area of the Gulf of Mexico, Diamond said in the press statement.

By partnering with Trelleborg, Diamond can integrate its riser design with Trelleborg’s synthetic foam expertise, which will augment the performance of the risers in terms of improved buoyancy, dependable cable protection, and effective thermal insulation, West commented.

“Development of this new technology for riser buoyancy is even more important as drilling moves into deeper waters,” said Ron Woll, senior vice president and chief commercial officer of Diamond, in a June 13 press statement. “We continually look for ways to improve the economics of offshore drilling for our customers, and this new buoyancy design will enhance drilling efficiencies in high-current environments.”

Diamond will receive a licensing fee for each Helical Buoyancy sold.


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