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Offshore: Is there a practical limit to water depths that can be accommodated with subsea equipment?
Garding: There is no real practical limit, up to 5,000 m (16,404 ft) is achievable; it just takes more work and qualification. There is, however, a limit on drilling technologies. As of now, we do not anticipate there will be many wells drilled over 3,000 m (9,842 ft) until the development of additional technology. Once there is a complete understanding of the drilling technology and well control for depths beyond 3,000 m, we can fully assess what our technology requirements will need to be.
Offshore: Where does the industry stand regarding deepwater intervention capabilities?
Garding: The industry is well-placed to perform riser-based interventions on deepwater wells with less than 10,000 psi pressure; however, most times it involves using a drilling rig as marine support. Where a real difference can be made going forward is by decoupling the drilling rig from the intervention equation and replacing it using a cost-effective vessel as marine support. Additional technology is required to perform cost-effective intervention on a routine basis on high-pressure wells, as well as to further increase the capability of riserless operations to drive down intervention costs. We recently executed the definitive agreements for the non-incorporated alliance with Helix and Schlumberger to focus on bridging these technology gaps and delivering end-to-end, integrated intervention solutions to our customers. This alliance is unique in the industry in that it contains all principle domain competencies encompassed in a subsea well intervention operation. We will draw on these competencies to develop innovative equipment and methodologies, allowing the industry to expand the existing intervention pressure envelope, as well as to enable more services to be performed from these cost-effective intervention vessels.
Offshore: What new technologies or approaches is OneSubsea offering with regard to flow assurance?
Garding: Flow assurance is the basis for specification and, consequently, the design of almost all production hardware and solutions we put on the seafloor. It actually starts at the outer reservoir no-flow boundary and follows the fluid journey through the reservoir, the well, the production gathering system, and through the topsides facilities. Through our parent companies, we have access to state-of-the-art simulation and assessment solutions and workflows that allow us to look at the entire process as one, and not in individual, compartmentalized domains. This allows for the running of upstream petrotechnical evaluations in parallel with production assurance and design processes, and cross checking this with our detailed knowledge about subsea hardware and solutions available.
Offshore: Discuss the pros and cons of electrical versus hydraulic control approaches to subsea equipment.
Garding: The use of electrical motors provides unparalleled advantages in regards to control, real-time feedback, and condition monitoring. Varying the output to the electric motor allows for partial stroke testing and increased power; features not possible with traditional hydraulic actuated valves and chokes. Another advantage is the speed of actuation. For a traditional hydraulic actuated choke installed at increased water depths, a fully open/fully closed cycle can take 20 minutes or more, whereas the use of electric actuated chokes can reduce the cycle time to several seconds if need be. Use of an electric system can continue for fields in extreme water depths, where enhanced availability and functionality are a must, and traditional hydraulic systems will no longer work.
Another positive aspect of an electric system is the short system start-up time. There is no need to pressure up hydraulic lines and/or to wait for accumulators to fill after multiple actuations or even after a total black out. An electric control system is fully operational within several minutes after start-up, in comparison to several hours for traditional hydraulic systems. An electric system is also more environmentally friendly, with zero discharge and no dumping of fluid, whereas with a traditional hydraulic system some control fluid may reach the sea.
As it stands now, the biggest drawback of an electric system is the pricing level. Current pricing levels are higher than for a traditional hydraulic system as a result of the small number built at this time. However, over time, as all-electric systems become more commonplace in the industry, these higher pricing levels should begin to decline.
The industry continues to move further offshore, into deeper waters, in a direction where a more sophisticated system requiring fast and accurate controls needs to be applied to subsea processing. The faster it is, the smaller it can be. By nature, electrical is faster than hydraulic, and in the long run can drive down costs for more complex seabeds. Electrical is the future, providing a more efficient and effective way to get the job done.
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