Anadarko Announces Commencement of Western Gas Partners, LP Initial Public Offering.

HOUSTON -- Anadarko Petroleum Corporation (NYSE:APC) today announced that Western Gas Partners, LP ("Western Gas Partners") has commenced its initial public offering of 18,750,000 common units representing limited partner interests, pursuant to a registration statement on Form S-1 previously filed with the U.S. Securities and Exchange Commission (the "SEC"). The underwriters will be granted a 30-day option to purchase up to an additional 2,812,500 common units. The common units will be listed on the New York Stock Exchange and traded under the symbol "WES."

Upon conclusion of the offering, the public will own an approximate 35% limited partner interest in Western Gas Partners, or an approximate 40% limited partner interest if the underwriters exercise in full their option to purchase additional common units. Anadarko will own the remaining equity interests in Western Gas Partners, including the general partner interest.

UBS Investment Bank, Citi, Credit Suisse and Morgan Stanley will act as joint book-running managers of the offering. Banc of America Securities LLC, Goldman, Sachs & Co., JPMorgan, Lehman Brothers and Wachovia Securities will act as senior co-managers, and Scotia Capital, Bear, Stearns & Co. Inc., Friedman Billings Ramsey and Stifel Nicolaus will act as co-managers, for the offering.

This offering of common units will be made only by means of a prospectus. A written prospectus satisfying the requirements of Section 10 of the Securities Act of 1933, when available, may be obtained from the offices of: (i) UBS Securities LLC, Prospectus Department, 299 Park Avenue, New York, New York 10171, phone: [phone] or 212-713-2626; (ii) Citigroup Global Markets Inc., Brooklyn Army Terminal, Attn: Prospectus Delivery Department, 140 58th Street, Brooklyn, New York 11220, phone: [phone]; (iii) Credit Suisse Securities (USA) LLC, Attn: Prospectus Department, One Madison Avenue, New York, New York 10010, phone: [phone]; or (iv) Morgan Stanley & Co. Incorporated, Attn: Prospectus Department, 180 Varick Street, 2nd Floor, New York, New York 10014, e-mail: [e-mail].

A registration statement relating to these securities has been filed with the SEC but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This news release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state in which such offer, sale or solicitation would be unlawful prior to registration or qualification under the securities law in any such state.

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 successfully create and market an initial public offering of a midstream Master Limited Partnership. See "Risk Factors" in the company's 2007 Annual Report on Form 10-K and other public filings and press releases. Anadarko undertakes no obligation to publicly update or revise any forward-looking statements.