Diamond Offshore Drilling

Corporate brand

An American offshore drilling contractor that operated semi-submersible rigs and drillships for oil and gas companies worldwide.

Last updated August 22, 2026

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Overview

Diamond Offshore Drilling was an American offshore drilling contractor serving exploration and production companies in the global oil and gas industry. Its business centered on contracting mobile offshore drilling units, including semi-submersible rigs and drillships, to oil companies that needed to drill exploration, appraisal, development, and production wells in offshore environments. The company was headquartered in Katy, Texas, and maintained major offices or operating presences in Australia, Brazil, Mexico, Scotland, Singapore, and Norway. The business traces its origins to Diamond M Drilling Company, established in 1964 after Don McMahon acquired the bankrupt onshore drilling company Brewster-Bartle from its bank creditors. McMahon named the new company after Diamond M Acres, his ranch near Simonton, Texas. Diamond M expanded from onshore work into offshore drilling and became publicly traded through an initial public offering in 1970. Its ownership and corporate structure changed substantially over the following decades. Kaneb Services acquired the company for $102 million, and Loews Corporation later purchased it for $48.5 million in 1989. A major transformation occurred in 1992, when Diamond M Corporation acquired ODECO from Murphy Oil for $358 million. The combined company briefly used the name Diamond M-ODECO Drilling before adopting Diamond Offshore Drilling, Inc. in 1993. Diamond Offshore returned to the public markets through an initial public offering in October 1995 and listed its shares on the New York Stock Exchange. In 1996 it acquired Arethusa in a stock transaction valued at approximately $516 million, further expanding its offshore drilling interests. Diamond Offshore competed in a capital-intensive and cyclical segment of the energy industry. Its results depended on oil and gas exploration budgets, dayrates, rig utilization, contract duration, shipyard costs, regulatory requirements, and the availability of technically capable drilling units. The fleet described in the company’s later history consisted of 15 rigs, including 11 semi-submersible platforms and four drillships. The company also invested in newer deepwater equipment, including a drillship ordered from Hyundai Heavy Industries in 2012 for approximately $655 million. The offshore drilling downturn placed considerable pressure on Diamond Offshore. In 2016, after discontinuing its quarterly cash dividend, the company was removed from the S&P 500 Index. Its 2019 revenue base was concentrated among several large customers, including Hess Corporation, Occidental Petroleum, Petrobras, and BP; United States operations accounted for more than half of reported revenue that year. The collapse in oil prices and the demand shock associated with the COVID-19 pandemic intensified the company’s financial difficulties. Diamond Offshore filed for bankruptcy protection in April 2020 and used the restructuring process to address debt and the weak offshore drilling market. Noble Corporation announced an agreement in June 2024 to acquire Diamond Offshore in a cash-and-stock transaction valued at approximately $1.6 billion. The transaction was completed in September 2024. Following the acquisition, Diamond Offshore ceased to operate as an independent publicly traded company, although its drilling assets, contracts, personnel, and capabilities became part of Noble’s offshore drilling platform.

History

Diamond Offshore Drilling developed from Diamond M Drilling Company, an enterprise formed in 1964 by Don McMahon. McMahon acquired the bankrupt Brewster-Bartle onshore drilling company from its bank creditors and named the successor after Diamond M Acres, his ranch near Simonton, Texas. The company expanded into offshore drilling as the Gulf of Mexico and other offshore basins became increasingly important to the petroleum industry. Diamond M became a public company through an initial public offering in 1970. Its ownership later shifted through a series of corporate transactions. Kaneb Services acquired the company for $102 million, before Loews Corporation purchased it for $48.5 million in 1989. In 1992, Diamond M Corporation bought ODECO from Murphy Oil for $358 million. ODECO was a significant offshore drilling business, and the acquisition materially reshaped Diamond M’s fleet and operating capabilities. The combined company temporarily operated under the name Diamond M-ODECO Drilling Inc. before adopting the Diamond Offshore Drilling name in 1993. Diamond Offshore returned to public ownership in October 1995 through an initial public offering and was listed on the New York Stock Exchange. The company continued to grow through acquisitions, including its 1996 purchase of Arethusa in a stock transaction valued at approximately $516 million. Arethusa had previously acquired Zapata Corporation, later known as HRG Group. Over time, Diamond Offshore established an international operating footprint with major offices or operational centers in Australia, Brazil, Mexico, Scotland, Singapore, and Norway, while retaining its Texas base. The company’s core activity was the ownership and contracting of mobile offshore drilling units. It operated semi-submersible rigs and drillships for oil and gas companies conducting offshore exploration, appraisal, field development, and production drilling. The fleet later described in company and reference materials included 11 semi-submersible platforms and four drillships. In May 2012, Diamond Offshore ordered a new drillship from Hyundai Heavy Industries for approximately $655 million, illustrating the scale of capital required to compete in the deepwater market. Offshore drilling is highly exposed to commodity cycles. When oil prices and exploration budgets weaken, contractors face lower dayrates, idle rigs, contract cancellations, and impairment or restructuring pressure. Diamond Offshore discontinued its quarterly cash dividend in 2016 and was subsequently removed from the S&P 500 Index. In 2019, its reported revenues were concentrated among Hess Corporation, Occidental Petroleum, Petrobras, and BP, while United States operations generated the majority of revenue. This customer and geographic profile reflected the company’s position as a specialist contractor rather than an integrated oil producer. The oil-price collapse and the sharp fall in energy demand during the COVID-19 pandemic further weakened the offshore drilling market. Diamond Offshore filed for bankruptcy protection in April 2020. The restructuring drew criticism related to the company’s receipt of funds associated with the CARES Act and the treatment of executive bonuses during the bankruptcy proceedings. The company also faced historical litigation concerning alleged asbestos exposure connected with drilling equipment acquired from a predecessor business. In June 2024, Noble Corporation announced an agreement to acquire Diamond Offshore in a cash-and-stock transaction valued at approximately $1.6 billion. The acquisition was completed in September 2024. Diamond Offshore therefore ceased to exist as an independent public company, with its fleet and operating activities incorporated into Noble Corporation’s offshore drilling business.

2024
Acquisition by Noble Corporation completed
[1]Diamond Offshore Drillingen.wikipedia.org
Noble Corporation completed its acquisition of Diamond Offshore in September, ending Diamond Offshore’s independent public-company status.
2020
Bankruptcy filing
[1]Diamond Offshore Drillingen.wikipedia.org
Diamond Offshore filed for bankruptcy protection during the severe offshore drilling and oil-market downturn.
2016
Dividend discontinued and S&P 500 removal
[1]Diamond Offshore Drillingen.wikipedia.org
The company discontinued its quarterly cash dividend and was later removed from the S&P 500 Index.
2012
New drillship ordered
[1]Diamond Offshore Drillingen.wikipedia.org
Diamond Offshore ordered a drillship from Hyundai Heavy Industries for approximately $655 million.
1996
Arethusa acquisition
[1]Diamond Offshore Drillingen.wikipedia.org
The company acquired Arethusa in a stock transaction valued at approximately $516 million.
1995
Second public offering
[1]Diamond Offshore Drillingen.wikipedia.org
Diamond Offshore completed another initial public offering and listed on the New York Stock Exchange.
1993
Diamond Offshore name adopted
[1]Diamond Offshore Drillingen.wikipedia.org
After briefly operating as Diamond M-ODECO Drilling, the company adopted the Diamond Offshore Drilling name.
1992
ODECO acquisition
[1]Diamond Offshore Drillingen.wikipedia.org
Diamond M Corporation acquired ODECO from Murphy Oil for $358 million.
1989
Loews acquires Diamond M
[1]Diamond Offshore Drillingen.wikipedia.org
Loews Corporation purchased Diamond M for $48.5 million after the company had previously been acquired by Kaneb Services.
1970
Diamond M becomes publicly traded
[1]Diamond Offshore Drillingen.wikipedia.org
The company completed an initial public offering and became a public drilling company.
1964
Diamond M Drilling Company is formed
[1]Diamond Offshore Drillingen.wikipedia.org
Don McMahon acquired Brewster-Bartle from bank creditors and established Diamond M Drilling Company, which later expanded into offshore drilling.

Products and positioning

A technically focused offshore drilling contractor serving deepwater and harsh-environment exploration and development programs.

Offshore drilling equipment and services
Semi-submersible drilling rigs
Diamond Offshore’s semi-submersible units were floating mobile offshore drilling platforms designed to operate in deepwater environments. The rigs supported exploration, appraisal, development, and production wells under contracts with oil and gas producers. Their capabilities depended on water depth, drilling specifications, station-keeping systems, equipment configuration, and the operating conditions of the target basin.
Offshore drilling equipment and services · 2012
Drillships
Diamond Offshore operated purpose-built drillships for deepwater drilling. These dynamically positioned vessels combine a marine hull with a drilling package and can relocate between offshore prospects more readily than fixed installations. The company invested in additional drillship capacity, including an order placed with Hyundai Heavy Industries in 2012.
Oilfield services
Contract offshore drilling services
The company’s principal commercial offering was contract drilling for international oil and gas companies. Customers hired Diamond Offshore’s rigs and crews for defined drilling programs, generally paying dayrates or other contract consideration. Service performance involved rig operations, drilling equipment, marine systems, safety management, maintenance, and compliance with offshore regulations.

Controversies

2020
CARES Act funding and executive bonus criticism
During and after Diamond Offshore’s 2020 bankruptcy filing, the company was criticized over its receipt of funds associated with the CARES Act and allegations that such funds were connected to executive bonuses during the restructuring process.
Source
2013
Asbestos exposure litigation
Employees of a predecessor business sued Diamond Offshore over alleged asbestos exposure after Diamond acquired six drilling rigs in 1989. In a 2013 SEC filing, Diamond acknowledged that equipment had been used in connection with the manufacture and use of asbestos-containing drilling mud while disputing or seeking indemnification for related liability.
Source

2024
Sale to Noble CorporationM&A
Background
After restructuring and continued consolidation in the offshore drilling sector, Diamond Offshore became an acquisition target for another major drilling contractor.
Action taken
Noble Corporation agreed to acquire Diamond Offshore in a cash-and-stock transaction and completed the deal in September 2024.
Aftermath
Diamond Offshore ceased to operate as an independent public company, and its assets and operations became part of Noble Corporation.
Announced transaction value. $1.6 billion (2024)
Source
2020
Bankruptcy restructuringOther
Background
The collapse in oil prices and reduced demand during the COVID-19 pandemic compounded existing weakness in the offshore drilling market.
Action taken
Diamond Offshore filed for bankruptcy protection in April 2020.
Aftermath
The filing placed the company’s debt, contracts, fleet, and corporate structure under a court-supervised restructuring process.
Source
2016
Suspension of quarterly cash dividendStrategy
Background
The offshore drilling industry was under pressure from weak oil prices, reduced exploration budgets, falling dayrates, and lower rig utilization.
Action taken
Diamond Offshore discontinued its quarterly cash dividend.
Aftermath
The company was subsequently removed from the S&P 500 Index, and the decision reflected the increasing need to preserve liquidity during the downturn.
Source
2012
Investment in a new deepwater drillshipProduct launch
Background
Diamond Offshore sought to expand and modernize its deepwater fleet in a market that required increasingly capable drilling units.
Action taken
The company ordered a drillship from Hyundai Heavy Industries for approximately $655 million.
Aftermath
The order represented a major capital commitment to high-specification offshore drilling capacity.
Drillship order value. $655 million order (2012)
Source

Recent events

2021-01-25
Diamond Offshore enters restructuring support agreement[3]Diamond Offshore签署重组支持协议rigzone.com
Reported: 2021-01-26
Diamond Offshore Drilling announced that it had entered into a plan support agreement with holders of over 70 percent of each of its senior unsecured notes and revolving credit facility loans regarding a financial restructuring transaction.
Unconfirmed
Diamond Offshore sues Beach Energy over drilling contract termination[4]Diamond Offshore就钻井合同终止起诉Beach Energynationalpost.com
Reported: 2020-04-27
Diamond Offshore sued Beach Energy after Beach terminated a $65 million drilling contract. Diamond Offshore said Beach claimed it had missed a contractual rig-delivery milestone, called the delay largely Beach's own making, and asked the court to declare the termination notice invalid.
2020-04-26
Diamond Offshore files for bankruptcy protection[5]Diamond Offshore申请破产保护foxbusiness.com
Reported: 2020-04-26
Diamond Offshore Drilling Inc. filed for Chapter 11 bankruptcy protection in Houston on Sunday, citing the sharply worsened offshore-drilling downturn amid the oil-price war and the Covid-19 pandemic.
Weekdays and relative dates follow the original report; their exact calendar dates have not been verified.

Sources15 sources

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