EXHIBIT 99.1


                                  NEWS RELEASE

                                                               Company Contacts:
                                       Investors: Frank Hopkins or Chris Paulsen
                                      Media and Public Affairs:   Susan Spratlen
                                                                  (972) 444-9001

           Pioneer Closes Acquisitions of Two Onshore U.S. Core Assets


Dallas,  Texas, July 14, 2005 -- Pioneer Natural  Resources  Company  (NYSE:PXD)
today  announced the closing of the previously  announced  purchase of assets in
two of its U.S.  onshore core areas,  the Permian  Basin and South Texas,  for a
combined purchase price of $177 million. The Permian Basin assets were purchased
from an affiliate of Occidental Petroleum  Corporation,  which recently acquired
these  assets  in  a  larger  transaction  from  an  affiliate  of  Exxon  Mobil
Corporation. The South Texas assets were acquired from an undisclosed seller.

These  purchases  add   approximately   70  million  barrels  of   substantially
undeveloped   proved  oil   equivalent   reserves   with  daily   production  of
approximately  1,800  barrels  of oil  equivalent  (BOE)  and an  estimated  800
undrilled  locations.  The Company expects to accelerate the pace of drilling in
each of these low-risk core areas beginning later this year and anticipates that
production  from the acquired  assets could exceed  10,000 BOE per day upon full
development of the proved reserves.

Pioneer is a large  independent oil and gas  exploration and production  company
with  operations in the United States,  Argentina,  Canada,  Equatorial  Guinea,
Nigeria, Sao Tome and Principe, South Africa and Tunisia. Pioneer's headquarters
are  in   Dallas.   For   more   information,   visit   Pioneer's   website   at
www.pioneernrc.com.

Except for historical  information contained herein, the statements in this News
Release are forward-looking statements that are made pursuant to the Safe Harbor
Provisions of the Private  Securities  Litigation  Reform Act of 1995.  Forward-
looking statements and the business prospects of Pioneer are subject to a number
of risks and  uncertainties  that may cause  Pioneer's  actual results in future
periods to differ materially from the  forward-looking  statements.  These risks
and uncertainties include, among other things, volatility of oil and gas prices,
product  supply  and  demand,  competition,  government  regulation  or  action,
litigation,  the  exercise of  preferential  rights to  purchase,  the costs and
results of drilling and operations, availability of equipment, Pioneer's ability
to replace  reserves,  implement its business plans, or complete its development
projects  as  scheduled,  access  to and cost of  capital,  uncertainties  about
estimates of reserves,  quality of technical data, and environmental and weather
risks.  These and other risks are  described in Pioneer's  10-K and 10-Q Reports
and other filings with the Securities and Exchange Commission.