Trelleborg and Safe Marine Transfer (SMT) are working to develop what they call a step-change technology for the offshore installation and subsea operation arena.
With US patents issued and additional ones pending, the new technology enables subsea deployment of equipment and chemical storage using SMT’s Subsea Shuttle powered via jointly developed Pumpable Buoyancy technology.
To continue to move this project forward, SMT, under contract with an international oil company, has recently completed Subsea Shuttle design testing and validation of performance at Seanic Ocean Systems’ onshore test tank facility in Katy, Texas. The scale model performed as predicted from Computational Fluid Dynamics (CFD) and dynamic simulation studies. Successful model tests of the Subsea Shuttle design performed with static buoyancy to lay the foundation for qualification of dynamically adjustable Pumpable Buoyancy.
Art J. Schroeder Jr., Principal with SMT, states: “This jointly developed Pumpable Buoyancy technology has the capability to reduce overall project costs by eliminating the requirement for heavy lift installation vessels for all kinds of subsea facilities including pumps, compressors, separators, and motor control systems. In the case of subsea chemical storage and injection, the technology will greatly extend tie-back distances to up to 100 miles. This innovation has the potential to dramatically improve economics and operational flexibility for both greenfield and brownfield developments.”
Antony Croston, Business Group Director with Trelleborg’s offshore operation, states: “The core technology in Pumpable Buoyancy, macro spheres, has been proven over the course of decades. What we are doing now is utilizing SMT’s patented method of deploying and retrieving the spheres as a service. It is an interesting new business model of having buoyancy when you need it, where you need it, for only the duration required for the job at hand.”
The new buoyancy technology facilitates the transportation of equipment or chemicals from the surface to the seafloor on the deck of the Subsea Shuttle. Through this method, equipment or chemicals can be placed on the seafloor during normal operation and brought back to the sea surface and then on to shore for equipment inspection, maintenance, repairs and upgrades as needed throughout the life of the field. Today this approach is cost prohibitive due to dependence on heavy lift vessel high day-rates and availability, Trelleborg explains.
Pumpable Buoyancy allows for real-time, in-operation modification of Subsea Shuttle uplift through the movement of specially engineered macro buoyancy spheres supplied by Trelleborg. The versatility of adjustable buoyancy presents significant benefits over current static buoyancy designs. Foremost is the ability to re-use a single buoyancy package across numerous Subsea Shuttle installations that are deployed for extended periods of time.
According to Trelleborg, substantial cost savings can be achieved through the Pumpable Buoyancy service model where buoyancy costs are distributed over the service of numerous Subsea Shuttle operations rather than for each individual operation under a fixed buoyancy design. Pumpable Buoyancy additionally allows for simplified retrieval of subsea equipment, where the weight may vary after operation (i.e. sand in separators, chemical injections, marine growth, and removal of part of equipment).