Pioneer Natural Resources Company and Pioneer Southwest Energy Partners L.P. Announce Merger Agreement

  Pioneer Natural Resources Company and Pioneer Southwest Energy Partners L.P.
  Announce Merger Agreement

Business Wire

DALLAS -- August 12, 2013

Pioneer Natural Resources Company (NYSE: PXD) (“Pioneer”) and Pioneer
Southwest Energy Partners L.P. (NYSE: PSE) (“Pioneer Southwest”) today
announced the execution of a definitive agreement and plan of merger (the
“Merger Agreement”) that would result in a merger whereby Pioneer Southwest
would become a wholly-owned subsidiary of Pioneer’s operating company, Pioneer
Natural Resources USA, Inc. (“Pioneer USA”), through a stock-for-unit exchange
(the “Merger”). Under the terms of the Merger Agreement, Pioneer Southwest’s
public unitholders would receive 0.2325 of a share of common stock of Pioneer
per Pioneer Southwest common unit surrendered pursuant to the Merger
Agreement, plus a whole share of Pioneer common stock in lieu of any
fractional share of Pioneer common stock otherwise issuable in the Merger. The
transaction is expected to result in 3.95 million additional shares of common
stock being issued by Pioneer. Regular quarterly distributions on the Pioneer
Southwest common units will continue until the closing of the Merger. The
terms of the Merger Agreement were unanimously approved by the Conflicts
Committee of the board of directors of the general partner of Pioneer
Southwest (the “Conflicts Committee”), who negotiated the terms on behalf of
Pioneer Southwest and is comprised solely of independent directors. The board
of directors of the general partner of Pioneer Southwest also approved the
terms of the Merger Agreement. In addition, Evercore Partners acted as
financial advisor to the Conflicts Committee and delivered a fairness opinion
to the Conflicts Committee in connection with the transaction.

The closing of the Merger is subject to certain closing conditions, including
the approval of the Merger Agreement and the transactions contemplated by the
Merger Agreement, including the Merger (the “Merger Proposal”), by the
affirmative vote of holders of a majority of the outstanding Pioneer Southwest
common units entitled to vote on the Merger Proposal at a special meeting of
the unitholders. Pioneer USA owns 100% of the membership interests in the
general partner of Pioneer Southwest and 52.4% of the 35,713,700 outstanding
common units of Pioneer Southwest. Pursuant to a voting agreement, Pioneer USA
has agreed to vote its common units in favor of the Merger Proposal. The
parties anticipate that the Merger will close in the fourth quarter of 2013.

The consolidation of the properties of Pioneer and Pioneer Southwest in the
Midland Basin in West Texas pursuant to the Merger is expected to facilitate
Pioneer’s plans to fully and optimally develop the area utilizing horizontal
drilling and is expected to provide organizational, operational and
administrative efficiencies.

Pioneer is a large independent oil and gas exploration and production company,
headquartered in Dallas, Texas, with operations in the United States.

Pioneer Southwest is a Delaware limited partnership headquartered in Dallas,
Texas, with current production and drilling operations in the Spraberry field
in West Texas.

This communication does not constitute an offer to sell any securities. Any
such offer will be made only by means of a prospectus, pursuant to a
registration statement filed with the Securities and Exchange Commission
(“SEC”).

In connection with the proposed Merger, a registration statement of Pioneer,
which will include a proxy statement and will constitute a prospectus of
Pioneer, and other materials will be filed with the SEC. Investors and
security holders are urged to carefully read the documents filed with the SEC
regarding the proposed transaction when they become available, because they
will contain important information about Pioneer, Pioneer Southwest and the
proposed Merger. When available, investors and security holders may obtain a
free copy of the proxy statement/prospectus and other documents containing
information about Pioneer and Pioneer Southwest, without charge, at the SEC’s
website at www.sec.gov.

Pioneer, Pioneer Southwest and certain of their respective directors and
executive officers may be deemed to be participants in the solicitation of
proxies from the unitholders of Pioneer Southwest in connection with the
proposed transaction. Information about the directors and executive officers
of Pioneer is set forth in its proxy statement for its 2013 annual meeting of
stockholders, which was filed with the SEC on April11, 2013. Information
about the directors and executive officers of the general partner of Pioneer
Southwest is set forth in Pioneer Southwest’s Annual Report on Form 10-K for
the year ending December 31, 2012, which was filed with the SEC on March 14,
2013. These documents can be obtained without charge at the SEC’s website
indicated above. Additional information regarding the interests of these
participants may be obtained by reading the proxy statement/prospectus
regarding the proposed transaction when it becomes available.

Except for historical information contained herein, the statements contained
herein related to the Merger and the transactions contemplated by the Merger
Agreement are forward-looking statements that are made in reliance on the Safe
Harbor Provisions of the Private Securities Litigation Reform Act of 1995.
Forward-looking statements of Pioneer and Pioneer Southwest are subject to a
number of risks and uncertainties that may cause Pioneer's or Pioneer
Southwest’s actual results in future periods to differ materially from the
forward-looking statements, including the risk that the proposed Merger is not
consummated. These and other risks are described in Pioneer's and Pioneer
Southwest’s annual, quarterly and other reports filed with the SEC. In
addition, Pioneer and Pioneer Southwest may be subject to currently unforeseen
risks that may have a materially adverse effect on them. Neither Pioneer nor
Pioneer Southwest undertakes any duty to publicly update these statements
except as required by law.

Contact:

Pioneer Natural Resources Company and Pioneer Southwest Energy Partners L.P.
Investors:
Frank Hopkins, 972-969-4065
Josh Jones, 972-969-5822
Mike Bandy, 972-969-4513
or
Media and Public Affairs
Susan Spratlen, 972-969-4018
Suzanne Hicks, 972-969-4020