As the offshore oil and natural gas industry continues its march into deepwater frontiers, the facilities that will be the mainstays of that push, subsea installations and floating production facilities, will take on a distinctively different look.
Much of the design changes will entail borrowing the basic concepts in use today and reconfiguring them in new ways. Other hallmarks of tomorrow’s deepwater production facilities will be increased automation, more modularization, improved size/weight ratios, longer tiebacks, and expanded use of subsea processing.
Tomorrow’s subsea installations
The days when all of the equipment and trees mounted on one-of-a-kind giant templates with integrated and form-fitting piping and connections are fading into the past, claims Brian Skeels, emerging technology manager, FMC Technologies.
“Clustered wells leading to manifolds connected by umbilical flying leads and jumper connections allow for smaller modular components that can be set on the seafloor side-by-side and then connected up,” he says. “This modular approach also lends itself to easier installation and a pay-as-you-go schedule. Subsea production facilities can be added later in a modular plug-and-play scenario to deal with production plateaus or changes in well count. Smart subsea field architects will add plug-in bases in the field pipelines that can accommodate the later installation of more infrastructure when it’s needed, without disturbing what was initially installed.
“Daisy-chained pipeline loop (like Canyon Express) or field hub (like Independence) approaches to field development will be the norm, since most oil companies will have to form consortiums to share in the infrastructure costs.”
Finally, oil and gas companies are accepting the notion that subsea metering, boosting, and separation are smart and economical means to address both infrastructure-lean areas of the world and longer offset distances, Skeels contends: “The bigger picture is getting the overall recovery rates of subsea fields up to be on par with conventional platform completions for the same cost.”
Olivier Saincry, Doris Engineering subsea systems manager, foresees the optimization of subsea system installations “residing in the use of autonomous equipment, maintenance work without the use of surface support vessels, and a number of topside processes being done subsea, limiting the number of links between the seabed and surface.”
Eric H. Namtvedt, president of FloaTEC, thinks that the optimized subsea solution will involve new technologies such as subsea processing and boosting, ESPs, all-electric systems to enable further step-outs, and compact tree designs.
Uri G. Nooteboom, vice-president, field development projects for INTEC, contends that the deepwater sector will see more long-distance tiebacks to existing infrastructure or all the way to the beach: “Distances will continue to increase, using technologies such as subsea pumping/compression, subsea processing, flowline heating, efficient subsea power delivery/generation, etc.”
Within the next 10 years, predicts Gary Shaw, technology leader, VetcoGray, a GE Oil & Gas business, the complete subsea processing plant is likely to become a reality where fluids and gas are extracted from the reservoir, analyzed, separated by fluid type, treated, and then pumped to processing facilities-or in the case of gas, compressed and then sent to be processed.
“In addition, it is also possible that the power to drive all this will be ‘resident subsea’ as well,” he says. “Many of the pieces of this puzzle are already being worked, beginning with the Troll subsea separation project that VetcoGray installed in 1999.
“This new subsea facility will also be managed by an advanced control system using powerful software and a multitude of seabed sensors to actively help maximize the hydrocarbon extraction rate.”
Tomorrow’s floating production facility
Kenneth Richardson, ABS vice-president of energy development, details these general criteria for the optimized floating production facility of the future:
- A local control station for subsea production and processing.
- An “incredible” amount of automation, thus permitting minimal personnel onboard and an uplink to a remote control site capable of long-term production management.
- A design that is current-friendly and event-survivable.
- A design that allows for maximum operation up-time.
“There are many designs and options out there,” he points out. “ABS marine engineers and naval architects conducting plan design reviews worldwide report many new designs are combining the basic ideas from spars, tension leg platforms, and semisubmersibles and arranging them in new configurations.”
From a class society perspective, the issue is which existing rules or risk methodologies should be applied so that the review of these new units can be undertaken to standards that offer safety levels comparable to more-traditional designs, Richardson notes.
“Many of these novel designs are destined for the Gulf of Mexico,” he says. “However, ABS offshore project development staff say they are also beginning to see increased interest in novel concepts for service in other parts of the world.”
Among some examples he cites is the MinDOC3 design from Alden “Doc” Laborde and William Bennett, designed over a period of 8 years in concert with a consortium of industry-leading firms. (The technology is currently owned by Durward International, a joint venture of Keppel FELS and TexBass.) Another example is the multicolumn floater from AGR Deepwater Development Systems Inc.
“It is not so much the technologies that are changing as it is combining or packaging the technologies in a different manner,” contends Richardson. “We may see a design that is a cross between a semisubmersible and a truss spar. For ABS, the question then becomes: How do we analyze and review the design in terms of its stability?”
Another instance has been a recent semisubmersible design that ballasts not like a semi but like a spar, he says, adding that this “passive hull” design is the first to have been incorporated within a Gulf of Mexico semisubmersible recently.
Other experts interviewed focused on weight and size ratios.
“The optimization of the floating production facility will be in the equipment that it carries (weight and size optimization) and the ease of fabrication/standardization of the floater,” says Saincry.
Namtvedt expands on that point, noting that in floating platform design, there is usually a trade-off between size and efficiency.
“The more ‘payload’ that is included on one platform, the less you pay for the ‘real estate’ per installed equipment; however, as the complexity increases and interdependencies of platform systems go up, so does the higher probability for something to go wrong, thereby shutting down total operation,” he says. “As a solution provider, FloaTEC is working on finding this balance for maximum efficiency in operations, while ensuring that the design and fabrication also come together in a construction-friendly manner. Given the ‘drivers’ coming from moving into harsher environments and increasing water and reservoir depths, I think we will see both small and highly targeted solutions, while certain field sizes and complexities will require even larger integrated platforms. Smaller, simpler designs and systems will ultimately provide better value.”
Skeels thinks that the spar will be floating production facility of the future.
“Its stability and storage capacity are only now being exploited, and its design can accommodate several drilling and production scenarios,” he says. “Gathering pipelines and sales lines will be accommodated by vertical production risers inside the spar’s hull. Deepwater steel catenary risers (SCRs), their weight, and offset distance will have to be rethought out for ultradeep water. Independence Hub may be the near-term practical limit for semisubmersible floating production facilities supporting SCRs in 8,000 feet of water.”
Shaw believes that producing fields requiring more frequent well intervention may favor a dry tree platform.
He adds, “Escalating costs in benign environments may make us think more seriously about production to floating barges. FPSOs are on the horizon in the Gulf of Mexico, and there are numerous subsea developments being planned around the world. The optimum production facility depends on several factors that change with locality as well as with time.” ]
