Anadarko Petroleum Corporation is a petroleum and natural gas exploration and production company headquartered in two skyscrapers in The Woodlands, Texas: the Allison Tower and the Hackett Tower, both named after former CEOs of the company.

The company has been the subject of multiple environmental cases, including the largest environmental contamination settlement in American history - the 2014 settlement related to the former Tronox subsidiary of Kerr McGee, a company purchased by Anadarko in 2006.

In addition to exploration and production, the company engages in the gathering, processing, and treating of natural gas, and the transporting of natural gas, crude oil, and natural gas liquids. The company also participates in the hard minerals business through its ownership of non-operated joint ventures and royalty arrangements.

As of December 31, 2016, the company had approximately 1.722 billion barrels of oil equivalent (1.053×10 GJ) of proved reserves, 52% of which were liquids and 48% of which were natural gas. In 2016, the company produced 792 thousand barrels of oil equivalent (4,850,000 GJ) per day.

The company’s operations in the United States accounted for 89% of total sales volumes during 2016 and 90% of total proved reserves at year-end 2016.

In the United States, the company has major holdings in the:

The company’s international operations accounted for 11% of total sales volumes during 2016 and 10% of total proved reserves at year-end 2016.

The company has holdings in:

Anadarko was formed in 1959 as a subsidiary of Panhandle Eastern Corporation Pipe Line Company after the discovery of large amounts of natural gas in the Anadarko Basin, which underlies the Texas Panhandle and Oklahoma Panhandle, and southwest Kansas.

In 1986, Panhandle Eastern Corporation distributed its interests in Anadarko to its shareholders via a corporate spin-off in 1986.

In 1999, the company purchased a 7.5-acre (30,000 m) tract in The Woodlands, Texas from the Woodlands Land Company to build an 800,000-square-foot (74,000 m), 32-story headquarters building, on the site. In 2012, the company began construction of another office tower adjacent to its headquarters. The company named its two office towers after former CEOs. The buildings were completed in 2014.

In April 2000, the company acquired Union Pacific Resources in a $4.4 billion transaction.

In June 2001, the company acquired Berkeley Petroleum Corporation for C$1.2 billion plus the assumption of C$400 million in debt.

In December 2003, Robert J. Allison, Jr. resigned as chief executive officer and would be replaced by James T. Hackett, previously the chief operating officer of Devon Energy.

In June 2006, the company acquired Western Gas Resources in a $5.3 billion cash transaction.

In August 2006, the company completed the acquisition of Kerr-McGee for $16 billion in cash.

In January 2007, the company sold assets in West Texas for $1 billion.

In February 2007, the company sold assets in Oklahoma and Texas for $860 million.

In January 2012, the company sold midstream assets to Western Gas Partners for $483 million.

In January 2012, the company announced a major natural gas find offshore Mozambique.

In 2015, the company made an offer to acquire Apache Corporation, but the offer was rejected.

In February 2016, the company sold its interest in the Springfield oil and gas gathering system, near the Eagle Ford shale, for $750 million to Western Gas Partners.

In March 2016, the company announced layoffs affecting 1,000 employees, or 17% of its staff. The layoffs were the result of weak commodity prices.

In January 2007, the company sold its assets in the Eagle Ford to Sanchez Energy and The Blackstone Group for $2.3 billion.

Anadarko owned a 25% non-operating minority interest in the Macondo Prospect, which was owned 65% by and operated by BP and was affected by the Deepwater Horizon oil spill.

In early 2010, BP billed Anadarko more than $272 million as a partial payment for its share of cleanup and response costs in the Gulf, according to a bill that was sent by BP and obtained by Talking Points Memo. Anadarko publicly suggested that it will not pay for costs associated with the oil disaster, claiming in a statement that BP was guilty of gross negligence or willful misconduct. Under the joint operating agreement, Anadarko was required to pay its 25% share of costs related to any incident—unless that incident was caused by its partner's gross negligence or willful misconduct.

In May 2011, MOEX Offshore, a subsidiary of Mitsui and owner of a 10% non-operating ownership interest in the Macondo Prospect, settled claims with BP for $1.07 billion.

In October 2011, Anadarko settled all claims with BP for $4 billion. Anadarko also transferred its 25% stake in Mississippi Canyon Block 252 (Macondo Prospect) to BP and was indemnified by BP for all costs related to the oil spill, including those arising under the Oil Pollution Act of 1990.

In December 2015, U.S. District Judge Carl Barbier ordered Anadarko to pay a civil fine under the Clean Water Act of $159.5 million, or $50 per barrel of oil spilled as a result of the Deepwater Horizon drilling rig explosion. The judge stated Anadarko was not at fault for the spill, but the company's 25% ownership stake made it responsible. Barbier wrote that the $159.5 million fine "strikes the appropriate balance between Anadarko's lack of culpability and the extreme seriousness of this spill." The fine came after BP and Anadarko had unsuccessfully appealed to the U.S. Supreme Court to reject Judge Carl Barbier's finding of negligence in the Deepwater Horizon accident.

In April 2014, Anadarko settled with the U.S. Department of Justice and the Environmental Protection Agency to pay $5.15 billion to clean up environmental waste sites around the country. It was the largest environmental contamination settlement in American history.

The environmental contamination sites were inherited by Anadarko after it purchased Kerr-McGee in 2005. As background, in 2006, Kerr-McGee spun off its Tronox subsidiary to offload 70 years of environmental dumping of toxic waste across 22 states beginning in the 1920s. The environmental damages included polluting Lake Mead in Nevada with rocket fuel, leaving behind radioactive waste piles throughout the territory of the Navajo Nation and dumping carcinogenic creosote in communities throughout the East, Midwest and South at its wood-treating facilities. According to one report, "Kerr-McGee, rather than pay for the environmental mess it created, decided to shift the liabilities between 2002 and 2006 into Tronox. Kerr-McGee, meanwhile, kept its valuable oil and gas assets." Anadarko then purchased the "clean" portion of Kerr-McGee free of its legacy of environmental dumping.

In 2009, shareholders of Tronox sued Anadarko, as successor to Kerr-McGee, for having misled investors about the large environmental and other debts Tronox would inherit from Kerr-McGee.

The United States Department of Justice, on behalf of the United States Environmental Protection Agency, sued Anadarko for $25 billion.

In April 2014, the parties reached a $5.15 billion settlement with Anadarko in the largest environmental contamination settlement in American history.