Transocean
A Swiss multinational offshore drilling contractor specializing in deepwater and harsh-environment drilling.
Last updated August 26, 2026
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Overview
Transocean is a Swiss offshore drilling contractor whose principal business is providing mobile offshore drilling units, crews, and associated services to oil and gas companies. Its customers have included major international energy producers such as Shell, Equinor, Chevron, BP, and Petrobras. The company operates through a fleet that has historically included ultra-deepwater drillships, dynamically positioned semisubmersible rigs, harsh-environment semisubmersibles, and jackup units. Its principal executive offices are in Steinhausen, Switzerland, and its international operating footprint has included the United States, Canada, Norway, the United Kingdom, Brazil, India, Singapore, Indonesia, and Malaysia. The business traces its lineage to The Offshore Company, created in 1953 when Southern Natural Gas Company acquired the DeLong-McDermott joint drilling operation. In 1954, The Offshore Company launched Rig 51 in the Gulf of Mexico, described as the first mobile jackup drilling rig. The enterprise later became a public company, was reorganized as a subsidiary of Southern Natural Gas, and adopted the name Sonat Offshore Drilling in 1982. Sonat spun off most of the drilling business during the 1990s, after which the company expanded through a series of major combinations. A major turning point came in 1996, when Sonat Offshore Drilling acquired Norwegian drilling group Transocean ASA. The enlarged business adopted the Transocean name and pursued increasingly capable deepwater equipment, including large drillships designed to drill substantially deeper wells than the prevailing generation of offshore rigs. In 1999, it combined with Schlumberger's Sedco Forex offshore drilling business in a stock transaction. In 2000, it acquired R&B Falcon, adding a large fleet and the Deepwater Horizon rig. The 2007 merger with GlobalSantaFe further enlarged the fleet and strengthened the company's position as one of the world's leading offshore drilling contractors. Transocean's technological identity has been associated with high-specification drilling in technically difficult environments. Its rigs have supported wells in deep and ultra-deep water, including record-setting operations in the Gulf of Mexico. The company also expanded its harsh-environment capabilities through the 2011 acquisition of Aker Drilling and broadened its fleet through the 2018 acquisition of Songa Offshore. Later in 2018, it acquired Ocean Rig, adding additional ultra-deepwater drilling assets. The company has also faced substantial operational, legal, environmental, and reputational challenges. The 2010 explosion and sinking of the Transocean-owned Deepwater Horizon, while drilling for BP in the Gulf of Mexico, killed 11 workers and caused a prolonged oil spill. Transocean was later found partially responsible for the disaster and became involved in extensive civil, criminal, regulatory, and compensation proceedings. Other incidents involving its equipment or operations included fatalities, explosions, maintenance findings, the 2011 Frade-field leak off Brazil, and the 2016 grounding of Transocean Winner in Scotland. Following a prolonged downturn in offshore drilling, Transocean sold or retired lower-specification and idle units and concentrated more heavily on deepwater and harsh-environment assets. It sold 38 shallow-water rigs in 2012 and was removed from the SIX Swiss Exchange in 2016. The company remained listed in the United States and continued seeking contract extensions and new work for its modern fleet. In the reference material, Keelan Adamson became chief executive in April 2025, while several rig contracts and asset disposals were reported later that year. Transocean's financial performance remains closely tied to offshore exploration and production budgets, day rates, fleet utilization, contract duration, customer credit quality, and the industry's transition in response to energy-market and climate-policy pressures.
History
Transocean's corporate history begins with the offshore-drilling activities of Southern Natural Gas Company. In 1953, Southern Natural Gas created The Offshore Company after acquiring the DeLong-McDermott joint drilling operation. The new business launched Rig 51 in 1954 in the Gulf of Mexico; the unit is commonly identified as the first mobile jackup rig. The Offshore Company went public in 1967 and became a wholly owned Southern Natural Gas subsidiary in 1978. After Southern Natural Gas adopted the Sonat name, the drilling unit became Sonat Offshore Drilling in 1982. Sonat Offshore Drilling was partially separated from its parent in the early 1990s. William C. O'Malley became its first chief executive in 1992, Sonat distributed most of its ownership in 1993, and the parent sold its remaining stake in a secondary offering in 1995. The company then pursued international expansion. In 1996, it acquired Norwegian drilling group Transocean ASA for approximately $1.5 billion and adopted the Transocean identity. The combination supported a strategic move toward very large drillships and increasingly deep offshore wells. One of the early examples was Discoverer Enterprise, a large drillship designed for operations beyond the depth capabilities of many earlier rigs. In 1999, Transocean combined with Sedco Forex, Schlumberger's offshore drilling subsidiary. Sedco had originated in the United States, while Forex had roots in French drilling operations in North Africa; their corporate histories had already converged under Schlumberger. The transaction created a larger international contractor with a broader rig portfolio. In 2000, Transocean acquired R&B Falcon in a transaction valued at approximately $17.7 billion. The deal added a very large offshore fleet and brought the Deepwater Horizon into Transocean's portfolio. In 2007, Transocean merged with GlobalSantaFe, creating another major increase in scale and adding Robert E. Rose as chairman. The enlarged company developed a strong position in technically demanding drilling. In 2005, Discoverer Spirit drilled a record-setting offshore well, and in 2009 Deepwater Horizon drilled an even deeper well in the Gulf of Mexico. The emphasis on complex wells and high-specification rigs helped differentiate Transocean from contractors focused primarily on shallow-water units. The company subsequently reduced its exposure to older shallow-water equipment, selling 38 shallow-water rigs in 2012. Transocean's expansion was accompanied by legal and safety controversies. In 2007, the United States Department of Justice and Securities and Exchange Commission alleged violations of the Foreign Corrupt Practices Act relating to payments to Nigerian customs officials. Transocean acknowledged conduct underlying the allegations and agreed to a monetary settlement. The company also experienced a series of workplace incidents, including fatalities on the Transocean Leader, an explosion in Galveston Bay, the Bourbon Dolphin supply-boat disaster while servicing Transocean Rather, and other vessel-related deaths. The most consequential event was the April 2010 Deepwater Horizon disaster. The semisubmersible rig exploded while working for BP in the Gulf of Mexico, killing 11 people and injuring others. The rig was destroyed and sank, and oil flowed from the damaged well for approximately 87 days. The accident generated extensive investigations, litigation, regulatory action, and compensation proceedings. Responsibility was contested among Transocean, BP, and Halliburton, but Transocean was ultimately found partially responsible for the disaster. The event significantly damaged the company's reputation despite its assertion that several conventional safety statistics for 2010 were strong. Transocean continued reshaping its fleet during the offshore downturn. It acquired Aker Drilling in 2011, adding four harsh-environment rigs, completed the acquisition of Songa Offshore in January 2018, and acquired Ocean Rig later that year. The company also dealt with further incidents, including a 2011 drilling leak at the Frade field off Brazil involving Sedco 706 and the 2016 grounding of Transocean Winner near the Isle of Lewis in Scotland. In 2013, Transocean entered the S&P 500, but in 2016 it delisted from the SIX Swiss Exchange. In the 2020s, Transocean remained focused on contracting modern deepwater and harsh-environment assets. The supplied reference material identifies Keelan Adamson, formerly chief operating officer, as chief executive from April 2025. It also reports drilling activity by Mighty Barents, the sale of four long-idle rigs in September 2025, and extensions of two Petrobras and BP contracts in October 2025. These developments illustrate the continuing effort to improve fleet utilization and concentrate capital on assets with stronger technical and commercial prospects.
- 2025
Leadership and fleet developments
[1]Keelan Adamson became chief executive, while the reference material also reports new drilling activity, the sale of four idle rigs, and contract extensions with Petrobras and BP.
- 2018
Songa Offshore and Ocean Rig acquisitions
[1]Transocean completed its Songa Offshore acquisition and later acquired Ocean Rig, strengthening its deepwater and harsh-environment fleet.
- 2016
SIX Swiss Exchange delisting
[1]The company delisted its shares from the SIX Swiss Exchange and left the Swiss Market Index.
- 2013
Addition to the S&P 500
[1]Transocean was added to the S&P 500 index, replacing Dell.
- 2012
Shallow-water fleet reduction
[1]The company sold 38 shallow-water rigs and emphasized high-specification deepwater assets.
- 2011
Aker Drilling acquisition
[1]Transocean acquired Aker Drilling and added four harsh-environment rigs.
- 2010
Deepwater Horizon disaster
[1]An explosion destroyed the rig, killed 11 workers, and caused a prolonged Gulf of Mexico oil spill.
- 2009
Deepest well record by Deepwater Horizon
[1]Deepwater Horizon drilled a 35,050-foot well in the Gulf of Mexico, according to the reference material.
- 2007
GlobalSantaFe merger
[1]The merger with GlobalSantaFe substantially expanded Transocean's scale and fleet.
- 2005
Discoverer Spirit deepwater record
[1]Discoverer Spirit drilled an offshore well reported as reaching 34,189 feet.
Products and positioning
Premium offshore drilling contractor focused on technically complex deepwater, ultra-deepwater, and harsh-environment projects.
Offshore drilling unit
Ultra-deepwater drillships
Large dynamically positioned drilling vessels designed for exploration and development wells in deep and ultra-deep water. Transocean's drillship portfolio has included units capable of working in technically demanding Gulf of Mexico and international projects, with integrated drilling equipment, marine systems, and offshore crews.
Offshore drilling unit
Deepwater semisubmersible rigs
Semi-submersible rigs use partially submerged pontoons and columns to provide stability in deepwater environments. They are contracted for exploration, appraisal, and development work where water depth, well complexity, or environmental conditions exceed the practical range of conventional jackups.
Offshore drilling unit
Harsh-environment semisubmersibles
Specialized semisubmersible rigs engineered for severe weather and difficult offshore conditions, particularly in the North Sea and near Norway. These units support drilling programs requiring enhanced station keeping, structural resilience, and equipment suited to challenging metocean conditions.
Offshore drilling unit · 1954
Mobile jackup rigs
Jackup rigs are mobile units that tow to a location and raise their hull above the sea surface on extendable legs. They were central to the company's early Gulf of Mexico business, although Transocean later reduced its shallow-water exposure in favor of deepwater and high-specification assets.
Service
Contract offshore drilling services
Transocean contracts rigs, offshore personnel, drilling crews, and operational capabilities to oil and gas companies. Contracts commonly cover a defined rig, operating period, geographic area, and day-rate or related commercial structure, with the customer retaining responsibility for the broader well program.
Controversies
2020
Greenpeace fined £80,000 over BP rig protest
A Scottish court fined Greenpeace UK £80,000 for breaching an interdict obtained by BP rig operator Transocean in connection with Greenpeace’s protest blocking BP’s oil rig. Greenpeace said it would continue its campaign against the drilling.
2011
Frade-field drilling leak in Brazil
Sedco 706, operated by Transocean for Chevron, was involved in a leak at the Frade field off Brazil. Brazilian authorities pursued action against the parties, and the matter was settled without a finding of fault or liability according to the reference material.
2010
Deepwater Horizon explosion and Gulf of Mexico oil spill
Deepwater Horizon exploded on April 20, 2010, while drilling for BP. Eleven workers died, the rig sank, and oil flowed into the Gulf of Mexico for approximately 87 days. Transocean faced extensive litigation and criticism, and was later found partially responsible for the disaster.
2007
Foreign Corrupt Practices Act case
United States authorities alleged that Transocean approved improper payments made through freight-forwarding agents to Nigerian customs officials. The company admitted conduct underlying the allegations and agreed to a reported settlement of $13.44 million.
Brand decisions
2018
Acquire Songa Offshore and Ocean RigM&ABackground
Transocean continued consolidating and upgrading its offshore drilling portfolio.
Action taken
The company completed the Songa Offshore acquisition in January and acquired Ocean Rig later in the year.
Aftermath
The transactions added harsh-environment and ultra-deepwater assets during a difficult offshore market.
2012
Concentrate on high-specification deepwater rigsStrategyBackground
Transocean sought to reduce exposure to lower-specification and shallow-water assets.
Action taken
The company sold 38 shallow-water rigs and narrowed its strategic emphasis to high-specification deepwater units.
Aftermath
The fleet became more concentrated in deepwater and technically complex drilling.
2011
Acquire Aker DrillingM&ABackground
Harsh-environment drilling capability was strategically important in the Norwegian and North Sea markets.
Action taken
Transocean acquired Aker Drilling and its four harsh-environment rigs.
Aftermath
The transaction expanded Transocean's presence in demanding northern offshore environments.
2007
Merge with GlobalSantaFeM&ABackground
The company aimed to expand its fleet and strengthen its position among international offshore drilling contractors.
Action taken
Transocean merged with GlobalSantaFe in a transaction reported as creating an enterprise value of approximately $53 billion.
Aftermath
The enlarged company became one of the industry's largest contractors, with Robert E. Rose becoming chairman.
2000
Acquire R&B FalconM&ABackground
Transocean pursued scale in offshore drilling and access to a large portfolio of rigs.
Action taken
The company acquired R&B Falcon in a transaction valued at approximately $17.7 billion.
Aftermath
Transocean gained a major offshore fleet, including Deepwater Horizon.
1999
Combine with Sedco ForexM&ABackground
Sedco Forex was Schlumberger's offshore drilling subsidiary and brought additional international drilling assets.
Action taken
Transocean completed a stock-based combination with Sedco Forex.
Aftermath
The transaction broadened the company's fleet and global operating platform.
1996
Acquire Transocean ASAM&ABackground
The company sought international scale and stronger deepwater capability.
Action taken
Sonat Offshore Drilling acquired Norwegian drilling group Transocean ASA and adopted the Transocean identity.
Aftermath
The combination became a platform for large drillships and deeper offshore drilling operations.
Recent events
- 2025
Mighty Barents begins drilling in a major European gas field[1]
Other
The Mighty Barents began drilling gas wells in a large European Union gas field, with production planned for a later date.
- 2025
Keelan Adamson becomes chief executive[1]
Leadership change
Keelan Adamson, previously Transocean's chief operating officer, took over as chief executive in April.
- 2018
Transocean completes Songa Offshore acquisition[1]
M&A
The transaction expanded Transocean's fleet and strengthened its harsh-environment and North Sea capabilities.
- 2018
Transocean acquires Ocean Rig[1]
M&A
The acquisition added Ocean Rig's ultra-deepwater drilling assets and broadened Transocean's high-specification fleet.
- 2016
Transocean delists from the SIX Swiss Exchange[1]
Other
The company's shares were removed from the SIX Swiss Exchange and the Swiss Market Index while its United States listing continued.
- 2015
Steven Newman steps down as chief executive[1]
Leadership change
Steven Newman left the chief executive role following a reported quarterly loss of $2.2 billion.
- 2012
Transocean sells shallow-water rigs[1]
Other
Transocean sold 38 shallow-water units as part of a strategic concentration on higher-specification deepwater drilling.
- 2011
Transocean acquires Aker Drilling[1]
M&A
The acquisition added four harsh-environment drilling rigs used in and around Norwegian waters.
Sources3 sources
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