Exhibit 99

NEWS

ANADARKO ANNOUNCES FIRST-QUARTER RESULTS

HOUSTON, April 30, 2012 – Anadarko Petroleum Corporation (NYSE: APC) today announced first-quarter 2012 net income attributable to common stockholders of $2.156 billion, or $4.28 per share (diluted). These results include certain items typically excluded by the investment community in published estimates. In total, these items increased net income by approximately $1.681 billion, or $3.36 per share (diluted) on an after-tax basis.⁽¹⁾ Cash flow from operating activities in the first quarter of 2012 was $1.891 billion, and discretionary cash flow totaled $1.922 billion.⁽²⁾

FIRST-QUARTER 2012 HIGHLIGHTS

“Anadarko delivered record operating results, generated more than $130 million of free cash flow and successfully appraised discoveries in Mozambique, the Gulf of Mexico and Ghana during the first quarter of 2012,” said Anadarko Chairman and CEO Jim Hackett. “The operating results were highlighted by record sales volumes, a year-over-year increase of 27,000 barrels per day from our liquids-rich U.S. onshore growth properties, and the startup of oil production at Caesar/Tonga in the Gulf of Mexico. In addition, we resolved the Algeria tax dispute in a mutually beneficial manner that resulted in a $1.8 billion benefit in the first quarter, of which we expect to receive approximately $1 billion in cash during 2012 and the balance during the first half of 2013. The resolution also included amended contract terms, which are expected to result in approximately 1.6 million barrels of additional oil volumes during 2012. This is reflected in our increased sales-volumes guidance range of 258 to 262 million BOE, with no corresponding increase in capital.”

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OPERATIONS SUMMARY

Sales volumes in the first quarter rose to 64 million BOE, or a record 704,000 BOE/d, averaging approximately 221,000 barrels of oil per day (BOPD), 80,000 barrels of natural gas liquids per day and 2.4 billion cubic feet of natural gas per day.

The company delivered a record 301,000 barrels of liquids per day, benefitting from a 50-percent year-over-year increase in liquids sales volumes from the five major liquids-rich plays highlighted during Anadarko’s March 13 Investor Conference (the Wattenberg, Eagleford, Permian, East Texas HZ and Greater Natural Buttes plays). The Wattenberg field in Colorado accounted for a significant portion of this growth, by ramping up year-over-year liquids sales volumes by approximately 12,000 barrels per day.

As referenced in the highlights, Anadarko achieved first production at the Caesar/Tonga mega project in the Gulf of Mexico in early March, and is currently producing more than 45,000 BOE/d from three wells. The partnership plans to drill a fourth well in the third quarter of this year. At Independence Hub, the Cheyenne East well was brought on line.

EXPLORATION SUMMARY

Anadarko and its partners drilled six successful deep-water exploration/appraisal wells during the first quarter of 2012. In West Africa, the Ntomme-2A and Enyenra-4A appraisal wells offshore Ghana encountered significant oil pay, enhancing the value and expanding the areal extent of the TEN (Tweneboa, Enyenra and Ntomme) complex. The company also successfully completed a drill-stem test at its Owo discovery well, which flowed at facility-constrained rates exceeding 20,000 BOPD from multiple zones. Offshore Sierra Leone, Anadarko and its partners encountered hydrocarbon pay at the Jupiter-1 prospect, and evaluation of the area is ongoing.

Offshore Mozambique in the Prosperidade complex, the company announced successful appraisal wells at Lagosta-2 and Lagosta-3 during the quarter. Anadarko and its partners also successfully conducted a drill-stem test at the Barquentine-2 well during the quarter and another at the Barquentine-1 well subsequent to quarter’s end. Both demonstrated outstanding reservoir characteristics, flowing at facility-constrained rates of approximately 100 million cubic feet per day (MMcf/d). The results of both drill-stem tests support well designs with potential flow rates of up to 200 MMcf/d. In April, following the successful Barquentine-4 appraisal well, Anadarko and its partners announced the completion of the appraisal drilling program in the complex. The company has now restarted its exploration program with the Golfinho prospect more than 15 miles northwest of Prosperidade.

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In February, Anadarko announced that the Heidelberg-2 appraisal well in the Gulf of Mexico encountered more than 250 net feet of oil pay, and a recent down-dip sidetrack appraisal well at Heidelberg confirmed an extension of up to 1,500 acres in the field. Pre-FEED (front-end engineering and design) work has been initiated at Heidelberg to evaluate development solutions. The company also recently spud the Spartacus well that will target subsalt layers in the vicinity of Anadarko’s Lucius mega project, which is currently under development.

Earlier this month, Anadarko announced encouraging results from its exploration drilling program in the Utica Shale play of eastern Ohio. The company plans to continue evaluating the liquids-rich potential of its 390,000-acre (gross) position in the Utica throughout 2012.

FINANCIAL SUMMARY

Anadarko ended the first quarter of 2012 with approximately $3.0 billion of cash on hand, and generated approximately $132 million of free cash flow⁽²⁾ during the first quarter, which includes the impact of $98 million of capital expenditures incurred by Western Gas Partners, LP (NYSE: WES). Anadarko retired approximately $131 million of 6.125 percent senior notes due in 2012, and reduced its net-debt-to-capital ratio ⁽²⁾ to 38 percent, compared to 41 percent at year-end 2011. Also, Moody’s Investors Service returned Anadarko’s senior unsecured rating to investment grade at Baa3, with a stable outlook. In addition, the company recently closed the divestiture of its South Texas assets, as well as finalized a $400 million joint-venture agreement at its enhanced oil recovery development in the Salt Creek field in Wyoming.

As described in the items affecting comparability on page 5 of the release, the company recorded an additional non-cash charge of $275 million related to the Tronox Adversary Proceeding. Also included in the items affecting comparability is the $1.8 billion benefit associated with the resolution of the Algeria tax dispute.

OPERATIONS REPORT

For more details on Anadarko’s operations, please refer to the comprehensive report on first-quarter 2012 activity. The report is available at www.anadarko.com on the Investor Relations page.

CONFERENCE CALL TOMORROW AT 9 A.M. CDT, 10 A.M. EDT

Anadarko will host a conference call on Tuesday, May 1, at 9 a.m. Central Daylight Time (10 a.m. Eastern Daylight Time) to discuss first-quarter results, current operations and the company’s outlook for the remainder of 2012. The dial-in number is 888.680.0890 in the United States or 617.213.4857

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internationally. The confirmation number is 35225653. For complete instructions on how to participate in the conference call, or to listen to the live audio webcast and slide presentation, please visit www.anadarko.com. A replay of the call will also be available on the website for approximately 30 days following the conference call.

FINANCIAL DATA

Eight pages of summary financial data follow, including current hedge positions and updated financial and production guidance.

⁽¹⁾ See the accompanying table for details of certain items affecting comparability.

⁽²⁾ See the accompanying table for a reconciliation of GAAP to non-GAAP financial measures and a statement indicating why management believes the non-GAAP financial measures provide useful information for investors.

Anadarko Petroleum Corporation’s mission is to deliver a competitive and sustainable rate of return to shareholders by exploring for, acquiring and developing oil and natural gas resources vital to the world’s health and welfare. As of year-end 2011, the company had approximately 2.54 billion barrels-equivalent of proved reserves, making it one of the world’s largest independent exploration and production companies. For more information about Anadarko, please visit www.anadarko.com.

This news release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Anadarko believes that its expectations are based on reasonable assumptions. No assurance, however, can be given that such expectations will prove to have been correct. A number of factors could cause actual results to differ materially from the projections, anticipated results or other expectations expressed in this news release, including Anadarko’s ability to drill, develop and commercially operate the drilling prospects identified in this news release and successfully plan, build and operate an LNG project. See “Risk Factors” in the company’s 2011 Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and other public filings and press releases. Anadarko undertakes no obligation to publicly update or revise any forward-looking statements.

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ANADARKO CONTACTS

MEDIA:

John Christiansen, john.christiansen@anadarko.com, 832.636.8736

Brian Cain, brian.cain@anadarko.com, 832.636.3404

Christina Ramirez, christina.ramirez@anadarko.com, 832.636.8687

INVESTORS:

John Colglazier, john.colglazier@anadarko.com, 832.636.2306

Clay Gaspar, clay.gaspar@anadarko.com 832.636.2541

Wayne Rodrigs, wayne.rodrigs@anadarko.com, 832.636.2305

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Anadarko Petroleum Corporation

Certain Items Affecting Comparability

Reconciliation of GAAP to Non-GAAP Measures

Below are reconciliations of cash provided by operating activities (GAAP) to discretionary cash flow from operations and free cash flow (non-GAAP), and net income (loss) attributable to common stockholders (GAAP) to adjusted net income (loss) (non-GAAP) as required under Regulation G of the Securities Exchange Act of 1934. Management uses discretionary cash flow from operations and free cash flow to demonstrate the Company’s ability to internally fund capital expenditures and to service or incur additional debt. It is useful in comparisons of oil and gas exploration and production companies because it excludes fluctuations in assets and liabilities. Management uses adjusted net income (loss) to evaluate the Company’s operational trends and performance.

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Anadarko Petroleum Corporation

Reconciliation of GAAP to Non-GAAP Measures

Presented below is a reconciliation of total debt (GAAP) to net debt (non-GAAP). Management uses net debt as a measure of the Company’s outstanding debt obligations that would not be readily satisfied by its cash and cash equivalents on hand.

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Anadarko Petroleum Corporation

(Unaudited)

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Anadarko Petroleum Corporation

(Unaudited)

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Anadarko Petroleum Corporation

(Unaudited)

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Anadarko Petroleum Corporation

Financial and Operating External Guidance

As of April 30, 2012

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Anadarko Petroleum Corporation

Financial and Operating External Guidance

As of April 30, 2012