As operators continue to look for cost savings in every aspect of their business, well operations have come under particular scrutiny, and several contractors are offering new tools for intervention assignments traditionally performed only by drilling units. Versatility is the key word as operators seek flexibility and multitasking capabilities from the latest offshore equipment.

Coflexip Stena, Cal Dive International and Sonsub are on the brink of bringing new vessels that they claim are capable of multitasking to the offshore market.
Cal Dive's Q4000 is soon to debut in the Gulf of Mexico, while Coflexip's recently christened Deep Blue is to go into service shortly in the Gulf on behalf of Kerr-McGee. Sonsub, meanwhile, has agreed to lease a new support vessel equipped for a variety of subsurface roles for its Innovator remotely operated vehicle.
Andy Scott, vice president of Cal Dive International, is scheduled to present a paper at this year's Offshore Technology Conference describing what new semisubmersibles can offer in the 21st century marketplace.
Without these new units, choice for well intervention in the Gulf has been limited.
Hitherto, if an operator hit a problem, they could either call on a drilling rig or call for Cal Dive's multiservice semisubmersible, Uncle John.
Although the Uncle John was built 23 years ago and has been upgraded since, the Q4000 will put it into the shade. The Uncle John is capable of coring ocean-bottom samples in water depths to 7,500 ft (2,288 m), conduct well operations in 3,000 ft (915 m) and handle construction work in 5,000 ft (1,525 m). It recently was deployed to install the subsea trees on the Diana field as part of ExxonMobil's Hoover/Diana development in 5,400-ft (1,647-m) waters.
However, when the US $150 million Q4000 multiservice vessel starts work - scheduled for the third quarter of this year - it will handle the same operations in 10,000 ft (3,050 m) of water at 15,000 psi with the help of a new intervention riser from the energy systems division of FMC, Scott said. A reelable annulus line gives the monobore riser a dual-bore capability.
Cal Dive also has worked with Schlumberger to ensure its new rig has the latest equipment and expertise for downhole testing, cleanup and other work. The new vessel will have a much larger deck for more storage and operating flexibility. It will be able to handle new, small-footprint coiled-tubing systems.
From the operator's point of view, the new-generation vessel is easier to mobilize than a drilling rig, particularly in tight times. From an economic standpoint, at $150 million the Q4000 represents at least a 50% saving on the initial construction cost of a new-build drilling rig. Consequently, this new unit can command a day rate that is much more competitive than a rig. This implies it could suffer less downtime due to a lack of contract work. The Q4000 also can handle multiple construction, mooring and intervention tasks on the same trip. In some cases, the ability to do more than one job at a time means it could save money. For example, in one trip, the new unit might J-lay pipe and umbilicals, carry out some deepwater construction work, then tackle some well intervention operations, thus avoiding the mobilization costs for three separate operations. The latest pipe-handling equipment gives it the same speed as a drilling rig, while dynamic positioning allows it to stay on station in less-than-hurricane weather and offer time-related savings of between 25% and 30% compared with moored vessels.
Furthermore, the elimination of cross braces below the working decks will allow supply boats or barges - up to 250 ft by 72 ft (76 m by 22 m) - to deliver seabed templates and other heavy equipment directly below the derrick for more flexibility on heavy jobs. The Q4000 also will be able to accommodate a moored barge underneath.
With a triple-redundant dynamic positioning system, the Q4000 will have a good station-keeping capability, allowing it to operate in adverse weather conditions through a design intended to eliminate some of the heave motions, Cal Dive claims. And less heave means reduced possibility of mistakes during installation and intervention work. "It will sit like a rock in anything but a hurricane," Scott said.
While new vessels are being added to the offshore market, cooperation between FMC Corp. and Cal Dive has resulted in a new intervention riser. This system is rated for 10,000 ft (3,000 m) and 15,000 psi, and is to be deployed from the Q4000.
The riser system will allow intervention on all vertical and horizontal subsea trees. Based on a modular design - like most systems these days - the system is based on a reelable 2-in. composite pipe. This will permit fluid circulation, flow tests and remediation of wells with hydrate fluids.
Speed of operation is one of the keys to the appeal of the Q4000. Because of the riser's slim bore size, it can be handled and run into a hole much faster than a conventional marine riser system.
Cal Dive and FMC claim their new system can land and latch onto a subsea tree within 6 hours of arriving on location.
Very aware of the need to stay on top of the intervention market, Coflexip Stena also has taken steps to keep ahead of the game by bringing its new-build Deep Blue to market.
This multipurpose intervention vessel was launched and officially named at Hyundai Mipo's Ulsan shipyard in South Korea recently following the successful completion of sea trials.
Like the Cal Dive unit, the Deep Blue is intended, as its name suggests, for deepwater operations. It will be rated to work in 8,200 ft (2,500 m) - allowing it access to most of the deepwater acreage under license around the world.
Versatility is key to its appeal too, since Coflexip's unit will be fitted out for reeled and J-lay pipeline installation, flexible lines and umbilicals, allowing it to complete a range of tasks - from subsea construction to installation.
However, at an estimated construction cost of $200 million, the Deep Blue vessel is pricier than Cal Dive's, but it will be put to the test a bit sooner. Coflexip is due to put its new boat to work midyear on Kerr-McGee's Boomvang and Nansen developments, where the ship is due to install the export pipeline system in a water depth of 3,600 ft (1,098 m).
Alliances
While Coflexip has been busy adding to its offshore construction fleet, Cal Dive has been establishing commercial alliances in a bid to build its position in the Gulf.
One agreement extends an existing alliance with Horizon Offshore for another 3 years. The agreement covers the provision of dive support vessels by Cal Dive for Horizon's pipelay barges. At the same time, Horizon is obliged to provide pipelay and derrick barge services to Cal Dive in the outer continental shelf.
Cal Dive also is to provide divers on Horizon barges in an extension of the existing agreement. Previously, Horizon was handling this aspect of its operations internally.
Martin Ferron, Cal Dive's president and chief operating officer, spoke of the benefits the partnership with Horizon has brought. "The alliance has achieved much in the 3 years that it has already been operating, despite the coincidental downturn in the Gulf of Mexico marketplace.
"Having come through the worst together, we are very excited about the alliance's prospects in the upturn that is just now gathering pace," Ferron said.
He said the extension also makes his company the biggest supplier of manned diving services in the Gulf, following the acquisition of Professional Divers of New Orleans, La.
Horizon President and Chief Executive Officer Bill Lam added: "This is another step in positioning Horizon and Cal Dive to take advantage of the coming upturn in the market."
Subsea specialist Sonsub, a Saipem subsidiary, has landed an important job carrying out construction work on the Canyon Express project in the Gulf. The work requires its new Innovator intervention and construction ship. Work was scheduled to start in April, and Sonsub was offering other slots.
Sonsub is taking on the new vessel through a charter agreement recently reached with Hornbeck Offshore.