Transocean Ltd.

Transocean was formed as a result of the merger of Southern Natural Gas Company, later Sonat, with many smaller drilling companies.

In 1953, the Birmingham, Alabama -based Southern Natural Gas Company created The Offshore Company after acquiring the joint drilling operation DeLong-McDermott from DeLong Engineering and J. Ray McDermott. In 1954, the company launched Rig 51, the first mobile jackup rig, in the Gulf of Mexico. In 1967, the Offshore Company went public. In 1978, SNG turned it into a wholly owned subsidiary. In 1982, it was changed to Sonat Offshore Drilling Inc., reflecting a change in its parent's name. [ non-primary source needed ] William C. O'Malley, an executive at Sonat's headquarters in Birmingham, was named the company's first Chief Executive Officer in 1992. In 1993, Sonat spun off the majority of its ownership in the company. Sonat sold its remaining 40% stake in the company during a secondary public offering in late 1995.

In 1996, the company acquired Norwegian group Transocean ASA for US$1.5 billion. Transocean started in the 1970s as a whaling company and expanded through a series of mergers. The new company was called Transocean Offshore. The new company began building massive drilling operations with drills capable of going to 10,000 feet (as opposed to 3,000 feet at the time) and operating two drill operations on the same ship. Its first ship, Discoverer Enterprise, cost nearly US$430 million and was 834 ft (254 m). The Enterprise class drillship is the largest of the drilling ships.

In 1999, Transocean merged with Sedco Forex, the offshore drilling subsidiary of Schlumberger in a $3.2 billion stock transaction in which Schlumberger shareholders received shares of Transocean.

Sedco Forex had been formed from a merger of two drilling companies, the S outh e astern D rilling Co mpany (Sedco), founded in 1947 by Bill Clements and acquired by Schlumberger in 1985 for $1 billion and French drilling company Forages et Exploitations Pétrolières (Forex) founded in 1942 in German-occupied France for drilling in North Africa. Schlumberger first got a foothold in the company in 1959 and then assumed total control in 1964, and renamed it Forex Neptune Drilling Company.

In 2005, the company's Discoverer Spirit rig set a world record for the deepest offshore oil and gas well of 34,189 ft (10,421 m).

In 2007, the US Department of Justice and the Securities and Exchange Commission filed a case against Transocean, alleging violations of the Foreign Corrupt Practices Act. The case alleged that Transocean paid bribes through its freight forwarding agents to Nigerian customs officials. Transocean later admitted to approving the bribes and agreed to pay US$13,440,000 to settle the matter.

In 2007, the company merged with GlobalSantaFe Corporation in a transaction that created a company with an enterprise value of $53 billion. Shareholders of GlobalSantaFe Corporation received $15 billion of cash as well as stock in the new company for their shares. Robert E. Rose, who was non-executive chairman of GlobalSantaFe, was made Transocean's chairman. Rose had been chairman of Global Marine prior to its 2001 merger with Santa Fe International Corporation.

In September 2009, its Deepwater Horizon rig established a 35,050 ft (10,680 m) well, the deepest well in history – more than 5,000 feet deeper than its stated design specification.

In 2012, the company sold 38 shallow water rigs and narrowed its focus on high-specification deepwater rigs.

In October 2013, the company was added to the S&P 500 index, replacing Dell.

In February 2015, CEO Steven Newman stepped down following a $2.2 billion quarterly loss.

Effective on 30 March 2016, the company delisted its shares from the SIX Swiss Exchange, at which time its shares were removed from the Swiss Market Index.

In February 2025, Transocean's drilling rig, Mighty Barents, began drilling gas wells in one of the EU's largest gas project, Neptun Deep, with plans to begin gas production in 2027.

In April 2025, Keelan Adamson, former COO of Transocean, took over as CEO of the company.

Transocean sold four of its idle rigs to an undisclosed buyer in September 2025. Included in the sale was the Discoverer India, Discoverer Clear Leader, Discoverer Americas, and Deepwater Champion, all of which had been cold stacked for years prior to the sale.

In October 2025, Transocean extended two drilling rig contracts totaling $243 million with Petrobras and BP.