As part of its growth strategy, Pride International committed to build four ultra-deepwater drillships at Samsung Heavy Industries in South Korea to expand its presence in the deepwater sector while offering customers high-specification drilling solutions for offshore well construction. In February, the company took delivery of the first drillship in this program, the Deep Ocean Ascension.

The Deep Ocean Ascension is now en route to the US Gulf of Mexico (GoM), where it is expected to begin a five-year contract with BP during 3Q 2010 following field testing and client acceptance. The company’s second ultra-deepwater drillship, the Deep Ocean Clarion, is expected to be delivered from the shipyard in August 2010 and to commence a five-year contract with BP in the GoM in 1Q 2011.

The final two projects in the construction program, the Deep Ocean Mendocino (which will go to work for Petrobras) and the Deep Ocean Molokai, are in earlier stages of construction. The Deep Ocean Mendocino is to be delivered from the shipyard in 1Q 2011, and the Deep Ocean Molokai is scheduled for delivery in 4Q 2011.

Rig improvements

The Deep Ocean Ascension, the first of Pride’s four newbuild ultra-deepwater drillships, is en route to the GoM. (Images courtesy of Pride International)

The Deep Ocean Ascension is 750 ft (228.75 m) long and has a breadth of 138 ft (42 m). Its 20,000-ton payload capacity allows for additional client and third-party equipment, and its 35,800 bbl fuel capacity allows for 60-day operational autonomy in normal conditions. There is adequate deck space for well testing operations as well as other third-party services. And it provides options for drilling operations, subsea tree running, and other subsea construction operations.

The high-specification capabilities of the Deep Ocean Ascension will meet the drilling needs associated with the increasing number of deepwater discoveries. The industry saw a record year in 2009 with 25 discoveries in water depths of 4,500 ft (1,373 m) and greater. Approximately 70% of these discoveries occurred in the traditional areas of exploration and development in the GoM, West Africa, and Brazil. In addition, customers are drilling increasingly complex wells that involve high temperatures, significant pressures, and complex architecture as total well depths increase.

Historically, floating rigs were configured with a single-load path from a derrick, which limited offline capabilities. Now solutions are available that range from a basic single-activity well center rig with offline capability to a dual-activity well center with offline capability, or increasing offline subsea construction capacity in either configuration. The client can also use additional offline subsea construction capability with the third offline load path, which includes the addition of an active heave compensating crane.

This 160-ton knuckle boom crane, outfitted to operate at depths up to 10,000 ft (3,050 m), is an essential feature for modern drillships that are involved in production and field development activities. It gives the client the ability to run and test subsea trees, templates, and umbilicals. It can also assist the remotely operated vehicle required to support drilling operations.

One of the most critical systems used in deepwater operations is the riser system. In selecting a new riser system design for the drillships, Pride conducted several studies to ensure the most appropriate system was selected to improve the safety, reliability, and efficiency of the riser systems. These studies covered the design of the handling, storage, and maintenance of the riser, as well as the riser design itself.

Based on these requirements, Pride selected a riser that it believes is the safest and most efficient on the market. It is designed to function as a pre-loaded connection in all conditions, which minimizes the effects of fatigue. The riser combines all the improvements of the new generation of riser systems and is expected to improve the efficiency of riser operations overall. The new design virtually eliminates manual intervention, which substantially reduces the risk of injury to rig personnel.

Power management is also key. Traditionally, power management was overseen in a way that shifted power from the drilling systems to the marine systems as approaching environmental or emergency conditions arose. Pride equips its drillships with six 7,000-kw engine generators configured in three separate engine rooms providing 42,000 kw of total power, which provides the rigs sufficient power to maintain all operations while also providing any power needed for environmental or emergency conditions. Maintaining position over the wellhead is accomplished by six azimuthing-type thrusters that rotate 360° for station keeping, propulsion, and steering; these are underwater dismountable with nominal power of 5.5 mw each.

Safety, efficiency

The Pride newbuilds are outfitted with a 160-ton knuckle boom crane, an essential feature for drillships involved in production and field development activities.

Failure modes, effects, and criticality analyses (FMECA) were applied to all major systems on the rig. In addition to the mandatory Class required FMECAs for the dynamic positioning and marine systems, Pride completed its own FMECAs to the remaining safety-critical systems and other marine support systems and on all of the drilling-related systems. The results of these analyses were applied to the vessel commissioning, system integration testing, and maintenance procedures, and were addressed in the operational procedures and processes where required.

More efficiency can be seen in the active mud system. On Pride’s new generation of rigs, the system is configured as a 6,000 bbl system and can be reconfigured to a 6,000 bbl mud system, a 6,000 bbl brine system, or a double-isolated split mud and brine system, giving each a 3,000 bbl capacity. This allows clients to use mud and brine independently, while the double isolation between the systems provides a safeguard against any contamination between the mud and the brine. In parallel to the active mud system, each of the new vessels has the capacity to store 2,800 bbl of base oil, 7,000 bbl of brine fluids, and 7,400 bbl of additional reserve mud. The combination of the active and bulk storage capacities provides clients with a flexible drilling fluid management system.

Advanced systems such as these allow drillers to work smarter. Smart technologies also help minimize downtime and improve efficiency, which leads to more client value. At the same time, constant attention must be paid to safety practices and continuous improvement. Accordingly, the way the company conducts hazard recognition and risk assessment has continued to evolve over the years. Manual handling has been greatly reduced on drilling rigs and automated equipment, and systems and processes allow workers to achieve quite a bit more on the rig floor. It is important that training keeps pace with that technology.

New discoveries in 2010 are on pace to equal 2009. The industry’s latest drillships are well-suited to meet the complex requirements in the new deepwater frontiers.