S PECIAL MARINE EDITION A computer-aided rendering of Transocean’s Enhanced Enterprise class drillship Discoverer Clear Leader shows the dual-activity der- rick, with stands of pipe made up offline in one derrick while drilling ahead with the second derrick. THERE ARE APPROXIMATELY 120 off- shore rigs under construction or on order today that run the gamut from premium jackups to what could safely be said to be the most sophisticated Latest equipment offshore rigs ever to be built. DRILLING CONTRACTOR sampled several rigs under construction that provide breakthrough technology in terms of rig technologies design and equipment. Most of the state-of-the-art equipment technolo- gies used on the rigs, whether it is a “simple” on new rigs pipe-handling system or dual-activity derricks, are intended to increase worker safety and pro- vide the highest performance and most efficient methods of conducting drilling and completion emphasize safety, operations. Drilling contractors building these rigs are also performance, looking forward as the industry moves to deeper waters and deeper wells. Transocean’s 3 drill- ships under construction, for example, will be capable of drilling to 40,000 ft in 12,000 ft of water. efficiency Ten shale shakers will be installed to handle mud By Jerry Greenberg, contributing editor and cuttings. Five mud pumps will be installed on the vessels, compared with 3 typically seen on offshore rigs. Three mud pumps appear to be the 40 May/June 2007 DDRILLINR I L L I N G CONTRACTOR S PECIAL MARINE EDITION norm these days for jackups, which also ties and other unique features of the BOP will undergo typical maintenance are designed with sufficient space to drillship, target the drilling of wells up to and testing. easily install a 4th mud pump. 40,000 f t total depth. The rigs will have a variable deckload of more than 20,000 Greater tree-handling capabilities will Power is a key factor in drilling opera- metric tons and will be capable of drill- save time during completions operations. tions today and in the future. Rowan ing in water depths of up to 12,000 ft. A dedicated area capable of holding Companies’ latest jackup design, the 3 large trees (approximately 100 tons 240-C Class, will have 6 Caterpillar The Discoverer Clear Leader will also each) is provided with all outfitting nec- generator sets for a total of 12,900 hp. utilize the company’s patented dual- essary to test the trees prior to running Premium Drilling’s jackups also feature activity technology to work simultane- them. Assembling these trees nearer ratings up to 12,500 hp. Like most jack- ously with 2 complete BOP stacks, lower the well center than on existing rigs will ups under construction, they feature a marine riser packages and pods, saving reduce handling on the rig. minimum 2 million-lbs hook load capac- ity, compared with 1.5 million lbs for the previous jackup generation. Comparison of Discoverer Enterprise (Enterprise class) and Discoverer Clear Leader (Enhanced Enterprise class) drillships The following reviews several drilling contractors’ latest new rig construction Discoverer Enterprise Discoverer Clear Leader programs with safety and performance enhancing technologies. Operating water depth 10,000 ft (3,048 m) 12,000 ft (3,660 m) Drilling depth capability 35,000 ft 40,000 ft TRANSOCEAN INC Storage capacities: In 2006, Transocean Inc announced the Riser storage 10,000 ft 12,000 ft construction of 3 Enhanced Enterprise class drillships to be built at Daewoo Cranes 4 each x 75 mt 4 each x 100 mt Shipbuilding and Marine Engineering Major drilling equipment: for long-term drilling contracts. Chevron Dual-activity derrick 2 x 1,050 tons 2 x 1,300 tons contracted 2 of the drillships while Top drive 2 x 750 tons 2 x 1,250 tons Hydro signed a contract for 1 of the Rotary 2 x 60.5 in./1,000 ton 1 x 75.5 in./1,000 ton (fwd) vessels. The 2 Chevron-contracted rigs, 1 x 60.5 in./1,000 ton (aft) Drawworks 2 x 1,000 tons CE EH-V 2 x 1,000 tons NOV AHC Discoverer Clear Leader and Discoverer Motion compensation 2 x crown mounted 2 x Active heave drawworks Inspiration, are scheduled for delivery in the 2nd quarter of 2009 and the 1st quar- Drilling mud/completion fluids system ter of 2010, respectively. The rigs will Liquid mud/completion fluids 15,400 bbls 20,000 bbls work in the US Gulf of Mexico initially. Active mud 6,000 bbls 8,000 bbls Reserve mud 9,000 bbls 11,600 bbls The third rig, as yet unnamed, is set for Slugging tanks 400 bbls 400 bbls delivery in mid-2009. Mud pumps 4 x 7,500 psi triplex 5 x 7,500 psi NOV HEX Shale shaker 8 x Brandt LCM-2D 10 x Brandt LCM-3D Revenues of approximately $493 mil- Subsea and well control lion are possible during the first 3 Marine riser (21 in x 75 ft joints) Class F (2.5mm lb) couplings Class G (3mm lb couplings) years of the Discoverer Clear Leader Blowout preventer 1 x 15,000 psi x 18 ¾ in. 2 x 15,000 psi x 18 ¾ in. contract. The final 2 years of the con- Diverter 2 x 60 in. bore 1 x 72 in. bore (fwd) tract are linked to the standard West 1 x 60 in. bore (aft) Texas Intermediate oil price, with a Well test provisions: floor of $40/bbl and a ceiling of $70/bbl Wellbore fluid storage 125,000 bbls 125,000 bbls that could result in potential revenues Tree handling 1 x 75 ton simultaneous 3 x 100 mt between $292 million and $365 million over that period. up to 4 days of testing and running the “On the newbuild rigs, fully assembled BOP and riser. trees will be lifted onboard in a single The nearly identical dynamically lift, and several trees can be tested and positioned, double hull drillships are “This capability is one of the first to be ready to be run to the seafloor,” Mr Hall designed to include the most advanced utilized on a regular basis, as most rigs explained. drilling capabilities in the offshore drill- operate with 1 BOP,” explained Mike ing industry, building on Transocean’s Hall, vice president, engineering and The new rigs also will feature five 7,500- Enterprise class drillship design. The technical services for Transocean. psi National Oilwell Varco Hex mud drillships will feature Transocean’s pat- pumps, compared with four 7,500 Triplex ented dual-activity drilling technology, Utilizing multiple complete BOPs can pumps on the earlier Enterprise rigs. allowing for parallel drilling operations save several days of maintenance and Additionally, the new vessels will have that is designed to save time and drill- testing of the BOPs between wells, which 10 Brandt LCM-3D shale shakers, com- ing costs in deepwater well construction can be particularly efficient in the Gulf of pared with 8 Brandt LCM-2D shakers on compared with conventional rigs. Mexico, where wells are relatively close the earlier rigs. The extra capacity will together, even if the vessel must mobilize provide additional flexibility to bypass a The dual-activity technology, along with to another block for the subsequent well. problem with 1 shale shaker without shut- a new and enhanced top drive system, With multiple BOPs, one will always be ting down operations. The design includes an expanded high-pressure mud pump ready for the next well while the second the latest cuttings-management technolo- system, expanded completions capabili- 42 May/June 2007 DDRILLINR I L L I N G CONTRACTOR S PECIAL MARINE EDITION gy throughout the cuttings system, includ- go, including the industry’s so-called ing sufficient storage capacity and an “workhorse” rig — the LeTourneau 116- auger system to move dry cuttings into a C class — recently introduced its 240-C container at the same level as the cuttings Class jackup rig that has been dubbed outflow. This process eliminates extra “the next workhorse.” Two of the 240- pumping or crane-handling operations. C class rigs are under construction at the LeTourneau shipyard in Vicksburg, “The entire system is designed as anoth- Miss., for delivery in June 2008 and er vehicle for reducing non-productive February 2009. time,” Mr Hall noted. According to Rowan, there are 52 116- The new drillships will feature 1,000-ton C class jackups in the worldwide fleet , drawworks and new, enhanced 1,250-ton including 31 that are over 20 years old top drive drilling systems being devel- and 21 that are over 25 years old. Of oped by Aker Kvaerner MH. Top drive the approximately 60 jackups under systems on the earlier Enterprise class construction, about 75% are in the size rigs were 750-ton units. The enhanced range of the 116-C class or slightly top drives are being designed with more larger, according to Rowan, with 50% robust components to reduce required of them having identical leg spacing maintenance and to make scheduled and or transom offset to the 116-C design. unscheduled maintenance quicker to sig- Additionally, all of the 116-C replacement Two of Rowan’s 240-C class rigs are nificantly reduce downtime. rigs under construction improve upon under construction at the Le Tourneau the environmental and payload capabili- The new 1,250-ton top drive is designed to shipyard in Vicksburg, Miss. significantly reduce non-productive time ties of the 116-C, and all have increased as it will be more powerful and robust drilling capacity and consumables stor- than existing 750-ton top drives.