As of March 2011, Maersk Drilling was awarded the honor of being the first deepwater drilling contractor to begin a new exploration well in the US Gulf of Mexico (GoM) nearly a year after the Deepwater Horizon accident. The Maersk Developer picked up anchors on March 21, 2011. One of three semisubmersibles brought online by Maersk in 2009, the rig’s highly advanced design and improved safety equipment passed the tightened technical requirements in the GoM with only a few minor adjustments.

With the success of its deepwater fleet, Maersk recently announced plans to invest US $1.3 billion in its first two ultra-deepwater drillships.

From deep to ultra-deep

Samsung Heavy Industries in South Korea will build the two ultra-deepwater drillships, which are scheduled for delivery in the second half of 2013. The contract, signed on April 5, also includes an option to buy two additional drillships.

The 748-ft (228-m) long drillships will be able to operate at water depths to 12,000 ft (3,650 m) and will be capable of drilling wells of more than 40,000 ft (12,200 m). An advanced dynamic positioning (DP) system will allow the drillships to automatically maintain a fixed position in severe weather conditions with waves to 36 ft (11 m) and wind speeds up to 85 ft/sec (26 m/sec). Similar to the philosophy applied to Maersk’s deepwater semisubmersibles, the drillship design includes features for high-efficiency operation including a double derrick, which allows simultaneous activities. The extensive storage areas and tank capacities provide an advantage when operating in areas with less developed infrastructure and limited presence of suppliers.

Pictured is the driller’s cabin from one of the newbuild deepwater semisubmersibles Maersk took delivery of last year. The company is using its experience with these rigs to design highly automated ultra-deepwater drillships.

Advanced automation

“Last year, we took delivery of the last in our series of three ultra-deepwater semisubmersibles,” said Frederik Smidth, chief technology officer, Maersk Drilling. “We are taking the experience from those rigs and actually pushing a bit further.” A standout feature to the ships on order is an improved level of automation using National Oilwell Varco’s (NOV) drilling package, which features a multimachine control system. The system uses a multitude of automated processes as opposed to remotely operated equipment. With the multimachine control system, the operator is present primarily as a safety feature and is required to confirm at certain points in the operation that it is safe to continue. With complete joy- stick control, the driller simply confirms the continuation of the multimachine system. “It is completely done from automation,” Smidth said.

Maersk’s ultra-deepwater semisubmersibles were the first rigs to use NOV’s multimachine system. “It’s been fairly successful, in our mind” Smidth said. “We are not just using automation for the sake of automation, or because we as engineers like to play with it. This system actually delivers a higher than average performance.” More importantly, this advanced level of automation improves efficiency by providing consistent results. “If you look at tripping speed, for instance, you might be able to do that faster with a really good operator for a short period of time. But to do it in a consistent manner, hour after hour, this level of automation is a huge advantage,” he added.

Maersk Drilling’s new ultra-deepwater drillships will have the capacity to build casing stands up to 16-in. in multimachine control. “We didn’t have multimachine control standbuilding at all on the semis,” Smidth said. The added feature is considered an advantage for an ultra-deepwater project where supplies and lack of infrastructure often can impact drilling operations.

Maersk also has added what it considers to be the latest advance in deepwater drilling riser technology. The ships will use GE Hydrill’s latest deepwater riser design capable of hands-free connection. The system is remotely operated, which means no personnel are on deck handling tools while connecting the riser. “For us, it is a question of safety. We have people away from moving parts,” Smidth said. This riser system is just now entering the market, but Maersk believes that by the time its drillships embark there will be an ample amount of field experience to draw from.

Upgradable design

The size of the newbuilds is an asset. “That is the good thing about these ships,” Smidth said. “They are huge.” Maersk designed its new vessels with increased capacity both for present operations and future upgrades. “We have a full dual mud system, so it’s easy to switch from one type of mud to another without having to wait,” he added. The increased capacity will ensure continuous operation. In addition, switching from oil-based to water-based mud becomes virtually seamless without the need to clean or empty the mud system between changes.

Fuel capacity also will provide an advantage for these ships. While the storage capacity for pipe and casing are comparable to similar drillships on the market, Maersk added more fuel capacity to surpass the standard. “We increased the fuel capacity on board to provide longer operational windows without the need to stop work for refueling,” Smidth said.

Maersk recently announced plans to invest $1.3 billion in its first two ultra-deepwater drillships, which are scheduled for delivery in the second half of 2013. The 748-ft (228-m) long drillships will be able to operate at water depths to 12,000 ft (3,650 m) and will be capable of drilling wells of more than 40,000 ft (12,200 m). (Images courtesy of Maersk Drilling)

Looking ahead to the possibility of future regulations, Maersk has designed its new ships with the capacity for a seventh RAM. A standard deepwater stack usually has six. “We have very good shear capacity in six RAMs,” Smidth said. “We did not order seven RAMs, but we have ensured that we have enough space for it if it becomes a requirement by the authorities or specific client request.”

One area Maersk is watching closely is dual gradient drilling. When drilling in ultra-deepwater and in very deep wells, mud weight margins are very tight. Mud that is too light allows kicks, and mud that is too heavy can be lost in the formation. Systems are being developed that allow drillers to use lighter mud, but this requires a vast amount of pumping capacity. For an offshore operation, deck space is a finite quantity and often can limit the amount of pumping equipment that is required for dual gradient drilling.

Two and a half years out, Maersk is looking at capitalizing on technology advances in this area. “We did not install the pumping capacity, yet. But there is space for it on the rig,” Smidth said. The current design contains five mud pumps instead of the standard four. He added, “We can easily install two or three more if required.”

Maersk is pushing to drive the ultra-deepwater market. By applying the latest advances in fully automated drilling packages and looking closely at storage capacity, its new-builds will find their niche in remote offshore areas.

“We don’t want to drive the industry for the sake of being the driver,” Smidth said. “We want to drive it in the direction where we see that we can add value. The overall philosophy is to cut the well construction time looking at all aspects of the process.”

Offshore