Drilling requires rigs, and despite the drop in utilization rates, there are a few hundred new rigs under construction around the world. The interesting thing about these newbuilds is that many are being built in recently constructed yards in countries where rig building is a relatively new enterprise. More land rigs are being built in China, Russia, and Europe, and new yards capable of building mobile offshore drilling units have opened in Vietnam, China, and Indonesia, with another yard scheduled to open in Brazil.

View of the drill trench from the stairs. (Images courtesy of University of Copenhagen)

The softest rig market in 4Q 2009 is for jackups. The fleet numbers about 380, and about 58 were still cold-stacked in October; an additional 66 were under construction. By the end of the year, 29 jackups will have been delivered in 2009. According to ODS-Petrodata estimates, the jackup fleet will number 446 by 2012.

There are about 173 semisubmersibles in the fleet, with 11 cold-stacked and 36 under construction, including the soon-to-be complete Sevan Driller, another innovative design introduced by Norway’s Sevan Marine ASA. A forecast by ODS-Petrodata indicates the semisubmersible fleet will grow to 209 by 2012.

Circular semi makes a splash

NEEM ice core drilling project (Images courtesy of University of Copenhagen)

The world’s first circular rig capable of drilling in ultra-deep water was completed earlier this year, the first sixth-generation semisubmersible completed in a Chinese shipyard.

The Sevan Driller will be able to drill to 40,000 ft (13,500 m) in water depths to nearly 12,500 ft (3,660 m) and can store up to 150,000 bbl of produced fluids. The design is based on Sevan’s stabilized platform hull technology. The rig was classed by Norway’s DNV.

Construction began at Cosco Shipyard Group’s Nantong shipyard in May 2007 and continued at Cosco’s Qidong shipyard in Shanghai in April 2009, where the derrick was added and the rig was named in a ceremony on June 28.

The Sevan Driller left the Qidong yard on Oct. 10 and successfully passed inclination tests, followed by thruster installation and sea trials. It is expected to cross the Atlantic shortly and will be delivered to Petrobras SA for a six-year contract in the Santos basin.

Drillship fleet expands

Drill ships are an increasingly large share of the worldwide offshore fleet. The first flurry of building activity was 1975-77, when 10 drillships were built. Another 16 drillships were added in the late 1990s, but the fleet numbered only 35 by 2006. There have been a dozen new drillships added to the fleet in the last four years, and 37 more are under construction.

In October, ODS-Petrodata estimated there were 46 marketable drillships in the fleet, with another one to be added before the end of 2009. The overall fleet will rise to 60 operational drillships in 2010, to 78 in 2011, and to 83 in 2012. With the influx of new deepwater and ultra-deepwater capacity, it is possible that the industry will see additional drilling milestones achieved more quickly.

Tiber pushes the limits

The industry has set many well-length records using extended-reach drilling, but deep vertical wells have been less common.

BP PLC’s Tiber well, 250 miles (400 km) southeast of Houston in Keathley Canyon Block 102, created a buzz in the Gulf of Mexico (GoM) this summer as one of the deepest wells ever drilled, reaching 35,055 ft (10,685 m) measured depth (MD), nearly vertical. Transocean drilled the well with the ultra-deepwater semisubmersible, Deepwater Horizon, in 4,132 ft (1,259 m) of water. This seems to be the deepest offshore well bore (vertically), delivering oil shows in multiple Lower Tertiary reservoirs.

Although the Tiber well bore is more than 6.5 miles (10.5 km) long, an extended-reach well drilled off Qatar last year by Maersk Oil Qatar surpassed it by a mile at more than 7.5 miles (12 km) long. Transocean drilled the BD-04A well for Maersk in May 2008 using the GSF 127 jackup. The well bore reached 40,320 ft (12,297 m) MD, with a horizontal section of 35,770 ft (10,910 m), before they ran out of drill pipe. n

Buckskin beats Jack

In February 2009, Chevron USA announced another Tertiary oil discovery in deep water at the Buckskin prospect in Keathley Canyon Block 872. The Stena Drillmax drillship drilled the Buckskin well to 29,404 ft (8,962 m) in 6,920 ft (2,109 m) water depth.

Buckskin is only 44 miles (71 km) west of the Jack prospect, which Chevron drilled in Walker Ridge Block 759 in 2004 and tested in 2006. The Jack well was drilled to 28,175 ft (8,588 m) total depth (TD) in 6,964 ft (2,123 m) water depth. Although the Buckskin well was in slightly shallower water, it surpassed the Jack well in TD. n

Scientific drilling milestone

A new international research effort on the Greenland ice sheet set a record for single-season, deep ice-core drilling this summer, recovering more than a mile of ice core that is expected to help scientists better assess the risks of abrupt climate change.

The North Greenland Eemian Ice Drilling (NEEM) project has 14 nations participating (US, Belgium, Canada, China, France, Germany, Iceland, Japan, Korea, the Netherlands, Sweden, Switzerland, and the United Kingdom), led by the University of Copenhagen, with significant funding from the US National Science Foundation.

In 2008, the project built a drilling research facility encompassed by a large dome. It includes a drilling rig for extracting 3-in.-diameter ice cores, drilling trenches, laboratories, and living quarters.

The ice core drill is about 44 ft (13.5 m) long, run on a 7.3-mm diameter cable and operated from the surface. It includes a torque section with three spacers and a downhole electric motor in a pressurized casing. Near the base of the ice sheet, the pressure is about 270 times the atmospheric pressure at sea level.

Arctic activity has helped push development of environmentally friendly drilling chemicals.

Researchers were satisfied with the performance of a new drilling fluid based on coconut oil this season. Drilling fluid and ice chips were pumped up between inner and outer core barrels to a chip holding chamber; the fluid was recycled. This reverse-circulation drilling system is similar in principle to that recently used by Encana Corp. to drill deep exploration wells through vuggy Miocene basalt in the Colombia River basin in northwest North America.

Drilling began in June 2009, and the NEEM team reached 5,767 ft (1,758 m) depth in early August. At that depth, the ice layers were dated at 38,500 years old, representing the cold glacial period that preceded the present interglacial (warm) period.

The 2009 field season was only about 100 days. During the 2010 drilling, researchers hope to reach bedrock.

Safety strides

The new Sevan Driller was completed this year and will be delivered to Petrobras for work in the Santos basin. (Image courtesy Sevan Marine ASA)

The global drilling industry’s lost time incident (LTI) rate for 2008 reached a record low of 0.49, as tabulated by the Incident Statistics program and administered and recently reported by the International Association of Drilling Contractors (IADC). The IADC has tracked and compiled accident and safety statistics since 1962. The incident rate is calculated on incidents per 200,000 manhours. Information for 2008 was contributed by 105 drilling contractors, representing about 78% of the worldwide rig fleet. The 2008 data accounts for 454.47 million manhours; participants reported 1,078 LTIs and 4,141 recordable incidents.

LTIs and recordable incidents in 2008 most commonly occurred to floormen (more than 40%), with about 25% to derrickmen and slightly less often to roustabouts.

Although the LTI rate decreased, the number of overall fatalities increased to 32 in 2008, up from 23 in 2007.

The IADC noted that employees with less than six months of experience accounted for 12 of the 32 deaths, an additional five people had worked for six to 12 months, and six more victims had one to five years of experience. More than half of those killed had one year experience or less, suggesting that newer employees are not fully aware of the dangers in the work environment. With continued emphasis on improving safety training, we hope that this trend can be reversed.