PIONEER NATURAL RESOURCES CO
10-K, 1999-03-23
CRUDE PETROLEUM & NATURAL GAS
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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
 
                                   FORM 10-K
 
              ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934
 
                  For the fiscal year ended December 31, 1998
 
                        Commission File Number: 1-13245
 
                       PIONEER NATURAL RESOURCES COMPANY
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                                                           <C>
                          DELAWARE                                  75-2702753
              (State or other jurisdiction of                    (I.R.S. Employer
               incorporation or organization)                   Identification No.)
 
 1400 WILLIAMS SQUARE WEST, 5205 N. O'CONNOR BLVD., IRVING,
                            TEXAS                                      75039
          (Address of principal executive offices)                  (Zip Code)
 
                 Registrant's telephone number, including area code:
                                   (972) 444-9001
 
             Securities registered pursuant to Section 12(b) of the Act:
</TABLE>
 
<TABLE>
<CAPTION>
                                                       NAME OF EACH EXCHANGE
               TITLE OF EACH CLASS                      ON WHICH REGISTERED
               -------------------                     ---------------------
<S>                                                   <C>
Common Stock, par value $.01......................    New York Stock Exchange
</TABLE>
 
       Securities registered pursuant to Section 12(g) of the Act:  None
 
INDICATE BY CHECK MARK WHETHER THE REGISTRANT (1) HAS FILED ALL REPORTS REQUIRED
TO BE FILED BY SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 DURING
THE PRECEDING 12 MONTHS (OR FOR SUCH SHORTER PERIOD THAT THE REGISTRANT WAS
REQUIRED TO FILE SUCH REPORTS), AND (2) HAS BEEN SUBJECT TO SUCH FILING
REQUIREMENTS FOR THE PAST 90 DAYS.  YES  X    NO ___
 
Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein and will not be contained, to the best
of Registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K.  [  ]
 
<TABLE>
<S>                                                           <C>
AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY
  NON-AFFILIATES OF THE REGISTRANT AS OF FEBRUARY 26,
  1999......................................................  $  485,536,206
NUMBER OF SHARES OF COMMON STOCK OUTSTANDING AS OF FEBRUARY
  26, 1999..................................................     100,300,023
</TABLE>
 
                      DOCUMENTS INCORPORATED BY REFERENCE:
 
                                      None
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                       PIONEER NATURAL RESOURCES COMPANY
 
                             CROSS REFERENCE SHEET
             Pursuant to National Policy Statement No. 47 (Canada)
                       (Annual Information Form ("AIF"))
 
<TABLE>
<CAPTION>
ITEM NUMBER AND CAPTION OF AIF                         HEADING OR LOCATION IN FORM 10-K
- ------------------------------                         --------------------------------
<S>                                                    <C>
1. Incorporation                                       Item 1.   Business
2. General Development of the Business                 Item 1.   Business
3. Narrative Description of the Business               Item 1.   Business
                                                       Item 2.   Properties
4. Selected Consolidated Financial Information         Item 6.   Selected Financial Data
                                                       Item 8.   Financial Statements and
                                                       Supplementary Data
5. Management's Discussion and Analysis                Item 7.   Management's Discussion and Analysis
                                                       of Financial Conditions and Results of
                                                                 Operations
                                                       Item 7A.  Quantitative and Qualitative
                                                       Disclosures About Market Risk
6. Market for Securities                               Item 5.   Market for Registrant's Common Stock
                                                                 and Related Stockholder Matters
7. Directors and Officers                              Item 10.  Directors and Executive Officers of
                                                       the Registrant
8. Additional Information                              Item 11.  Executive Compensation
                                                       Item 12.  Security Ownership of Certain
                                                       Beneficial Owners and Management
                                                       Item 13.  Certain Relationships and Related
                                                                 Transactions
</TABLE>
 
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     Parts I and II of this Report contain forward looking statements that
involve risks and uncertainties. Accordingly, no assurances can be given that
the actual events and results will not be materially different than the
anticipated results described in the forward looking statements. See "Item 1.
Business -- Competition, Markets and Regulation" and "Item 1. Business -- Risks
Associated with Business Activities" for a description of various factors that
could materially affect the ability of the Company to achieve the anticipated
results described in the forward looking statements.
 
                                     PART I
 
     Unless otherwise specified, all dollar amounts are expressed in United
States dollars. Certain oil and gas terms used in this Report are defined under
"Item 1. Business -- Definition of Certain Oil and Gas Terms".
 
ITEM 1. BUSINESS
 
GENERAL
 
     Pioneer Natural Resources Company ("Pioneer," or the "Company") was formed
in April 1997 as a Delaware corporation and, prior to August 7, 1997, had not
conducted any significant activities. Effective as of August 7, 1997, Parker &
Parsley Petroleum Company ("Parker & Parsley"), formerly a Delaware corporation,
and MESA Inc. ("Mesa"), formerly a Texas corporation, completed their business
combination pursuant to an Amended and Restated Agreement and Plan of Merger
dated as of April 6, 1997 (the "Merger Agreement"). On December 18, 1997, the
Company's asset base was significantly expanded by the acquisition of the
Canadian and Argentine oil and gas business of Chauvco Resources Ltd.
("Chauvco"), a publicly traded independent oil and gas company based in Calgary,
Canada.
 
     Both the merger with Mesa and the acquisition of Chauvco were accounted for
as purchases by the Company (formerly Parker & Parsley). As a result, the
historical financial, reserve and other statistical information for the Company
are those of Parker & Parsley prior to August 1997. The Company's financial,
reserve and other statistical information present the addition of Mesa's and
Chauvco's assets and liabilities as acquisitions in August and December 1997,
respectively.
 
     The Company's proved reserves at December 31, 1998 totaled 677 million BOE,
representing $1.6 billion in PV 10 Value. Of the total, United States reserves
represent 78 percent of the BOEs and 74 percent of the PV 10 Value.
 
     The Company's business activities are conducted through wholly-owned
subsidiaries and are comprised of the business activities formerly conducted by
Parker & Parsley, Mesa and Chauvco. Drilling and production operations are
principally located domestically in Texas, Kansas, Oklahoma, Louisiana, New
Mexico and offshore Gulf of Mexico and internationally in Argentina and Canada.
 
     The Company's executive offices are located at 1400 Williams Square West,
5205 N. O'Connor Blvd., Irving, Texas 75039; the Company's telephone number is
(972) 444-9001. The Company maintains other offices in Midland, Texas; Buenos
Aires, Argentina; Calgary, Canada; and Capetown, South Africa. At December 31,
1998, the Company had 1,016 employees, 475 of which were employed in field and
plant operations.
 
MISSION AND STRATEGIES
 
     The Company's mission is to provide shareholders with superior investment
returns through strategies that maximize Pioneer's long-term profitability and
net asset value. The strategies employed to achieve this mission are anchored by
the Company's long-lived Hugoton and West Panhandle gas fields and Spraberry oil
field reserves and production. Underlying these fields are approximately sixty
percent of the Company's proved oil and gas reserves which have a remaining
production life of approximately forty years. The stable base of oil and gas
production from these fields generate operating cash flows that allow Pioneer
the financial flexibility to protect long-term net asset values during cycles of
depressed oil or gas prices and, during favorable oil and gas price
environments, more aggressively pursue capital investment strategies of: (a)
developing and increasing
 
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<PAGE>   4
 
production from existing properties through low-risk development drilling and
other activities, (b) concentrating on defined geographic areas to achieve
operating and technical efficiencies, (c) pursuing strategic acquisitions in the
Company's core areas that will complement the Company's existing asset base and
that will provide additional growth opportunities, (d) utilizing or acquiring
technological and operating efficiencies to selectively expand into new
geographic areas that feature producing properties and provide
exploration/exploitation opportunities, (e) allocating the personnel and
technology necessary to increase the Company's exploration opportunities and (f)
maintaining financial flexibility to take advantage of additional exploration,
development and acquisition opportunities. Additionally, to further align the
interests of management and shareholders, Pioneer encourages high levels of
equity ownership among senior managers and the Company's Board of Directors. The
Company is committed to continuing to enhance shareholder investment returns
through adherence to these strategies.
 
BUSINESS ACTIVITIES
 
BUSINESS ENVIRONMENT
 
     The Company is an independent oil and gas exploration and production
company whose operating cash flows are primarily impacted by production volumes,
realized oil and gas prices, production costs, interest expense and general and
administrative expense.
 
     Approximately sixty percent of Pioneer's proved oil and gas reserves
underlie the Hugoton and West Panhandle gas fields and the Spraberry oil field,
which are characterized by long-lived, relatively stable oil and gas production.
These fields serve to reduce volatility in the Company's short-term production
volumes.
 
     The realized oil and gas prices that Pioneer reports are based on the
market price received for the commodity adjusted by the results of the Company's
hedging activities. See "Marketing of Production" below. Historically, worldwide
oil and gas prices have been volatile and subject to significant changes in
response to real and perceived conditions in world politics, weather patterns
and other fundamental supply and demand variables. Since the third quarter of
1997, there has been a declining trend in world oil prices and, more recently
but to a lesser extent, natural gas prices. During cycles of depressed commodity
prices, such as the current cycle, the Company has the ability to reduce its
capital investments, without a significant impact to production volumes, which
allows the Company to control long-term debt levels and to protect its net asset
values. See "Item 7. Management's Discussion and Analysis of Financial Condition
and Results of Operations".
 
     During 1998, the Company implemented cost containment measures intended to
reduce future production and administrative costs. These measures included the
closings of the Company's regional offices in Oklahoma City, Oklahoma, Corpus
Christi, Texas, and Houston, Texas and the elimination of approximately 350
employee positions. Associated with these measures, the Company recognized
reorganization charges of $33.2 million during 1998. See "Item 7. Management's
Discussion and Analysis of Financial Condition and Results of Operations" and
Note N to Notes to Consolidated Financial Statements included in "Item 8.
Financial Statements and Supplementary Data".
 
     The Company's interest expense is essentially dependent upon debt levels
and prevailing interest rates. Pioneer intends to reduce its capital
expenditures during 1999 to approximately $100 million and to divest certain oil
and gas assets in 1999 or 2000 for approximately $500 million to $600 million of
divestment proceeds. See "Asset Divestitures" below. The liquidity provided by
these actions is expected to allow the Company to reduce outstanding
indebtedness during 1999. Although the Company anticipates that these
divestments will occur in 1999 or in 2000, the finalization of the transactions
are contingent upon the Company's ability to find one or more purchasers willing
to purchase the non-strategic assets at prices acceptable to the Company and the
purchasers' ability to complete the transaction. There can be no assurances that
the Company will be successful in completing the divestitures in 1999 or in
2000. See "Item 7. Management's Discussion and Analysis of Financial Condition
and Results of Operations".
 
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<PAGE>   5
 
PRODUCTION
 
     The Company focuses its efforts towards maximizing its average daily
production of oil and gas through development and exploratory drilling,
production enhancement activities and acquisitions of producing properties.
Average daily oil and gas production have each increased every year since 1991
with the exception of 1996 when average daily production declined due to
significant property dispositions. Comparing 1993 to 1998, average daily oil and
NGL production has increased 327 percent and average daily gas production has
increased 352 percent, while production costs per BOE have declined 35 percent.
Production, price and cost information with respect to the Company's properties
for each of 1998, 1997 and 1996 is set forth under "Item 2.
Properties -- Selected Oil and Gas Information -- Production, Price and Cost
Data".
 
DRILLING ACTIVITIES
 
     The Company seeks to increase its oil and gas reserves, production and cash
flow by concentrating on drilling low-risk development wells and by conducting
additional development activities such as recompletions. From the beginning of
1994 through the end of 1998, the Company drilled 2,567 gross (1,777 net) wells,
93 percent of which were successfully completed as productive wells, at a total
cost (net to the Company's interest) of $1.3 billion. During 1998, the Company
drilled 568 gross (431 net) wells for a total cost (net to the Company's
interest) of approximately $430 million, 70 percent of which was spent on
development wells and related facilities. The Company's current 1999 capital
expenditure budget is $100 million, which the Company has allocated as follows:
$75 million to exploitation activities, and $25 million to exploration
activities.
 
     The Company believes that its current property base provides a substantial
inventory of prospects for future reserve, production and cash flow growth. The
Company's reserves as of December 31, 1998 include proved undeveloped and proved
developed non-producing reserves of 43.3 million Bbls of oil and NGLs and 369
Bcf of gas. The timing of the development of these reserves will be dependent
upon the commodity price environment, the Company's expected operating cash
flows and the Company's financial condition. The Company believes that its
current portfolio of undeveloped prospects provides attractive development and
exploration opportunities for at least the next three to five years.
 
EXPLORATORY ACTIVITIES
 
     Over the past three years, the Company has dedicated an increasing
percentage of its annual exploration/exploitation capital budget to exploratory
projects: 18 percent in 1996, 28 percent in 1997 and 30 percent in 1998. As a
result of the downturn in commodity prices, the Company's 1999 capital budget
has been limited to $100 million and the portion of the budget dedicated to
exploration activities is targeted at approximately $25 million. The Company
currently anticipates that its 1999 exploration efforts, although curtailed,
will be concentrated domestically in the Gulf of Mexico and onshore Gulf Coast
region. The Company will participate in one or two wells in the Gulf of Mexico
deep-water Mississippi Canyon Block 305 and in two wells in either the onshore
Gulf Coast area or in East Texas where several shallower exploration prospects
have been defined from Pioneer's 3-D database. The Company's exploration
programs in South Africa, Gabon, and the Gulf Coast transition zone are targeted
for comprehensive studies that will focus on analysis, ranking and timing of
prospects during 1999. Exploratory drilling involves greater risks of dry holes
or failure to find commercial quantities of hydrocarbons than development
drilling or enhanced recovery activities. See "Item 1. Business -- Risks
Associated with Business Activities -- Risks of Drilling Activities" below.
 
ASSET DIVESTITURES
 
     The Company regularly reviews its property base for the purpose of
identifying non-strategic assets, the disposition of which would increase
capital resources available for other activities and create organizational and
operational efficiencies. While the Company generally does not dispose of assets
solely for the purpose of reducing debt, such dispositions can have the result
of furthering the Company's objective of financial flexibility through decreased
debt levels.
 
                                        5
<PAGE>   6
 
     During 1998 and 1997, the Company's asset disposition activity primarily
consisted of the sale of oil and gas properties for proceeds of $21.9 million
and $115.7 million, respectively, which resulted in a 1998 pre-tax net loss of
$445 thousand and a 1997 pre-tax net gain of $5.0 million. During the year ended
December 31, 1996, the Company sold certain wholly-owned subsidiaries for
proceeds of $183.2 million resulting in a pre-tax gain of $83.3 million and
certain non-strategic domestic assets for proceeds of $58.4 million that
resulted in the recognition of a pre-tax net gain of $13.8 million. The proceeds
from the asset dispositions were used to reduce the Company's outstanding bank
indebtedness and to provide funding for a portion of the Company's capital
expenditures, including purchases of oil and gas properties in the Company's
core areas.
 
     The Company has announced its intentions to sell non-strategic oil and gas
assets for gross proceeds of $500 million to $600 million in 1999 and 2000. In
February 1998, the Company announced its intentions to sell domestic
non-strategic properties and subsequently signed a purchase and sale agreement
(the "Agreement") to sell certain oil and gas properties representing
approximately 10 percent of the Company's proved reserves. In December 1998,
Pioneer announced the re-negotiation of the Agreement and the sale of an
exclusive and irrevocable option to the counter-parties to purchase the same
properties on or before March 31, 1999. The proceeds associated with the
re-negotiated terms total $335 million, of which $41 million represents an
irrevocable option fee that has been paid to the Company as of December 31,
1998. The Company's realization of the remaining $294 million of proceeds, which
would be used to reduce outstanding indebtedness, is primarily dependent upon
the buyer's ability to finance the purchase and certain other contingencies
defined in the Agreement. As a result, there can be no assurance that the
divestiture of any or all of the properties will be completed or that the
remaining proceeds will be realized. The Company is continuing to review its
portfolio of oil and gas properties to identify other non-strategic properties
for divestiture. The realization of the Company's plans to divest of the other
non-strategic oil and gas properties in 1999 or in 2000 is contingent upon,
among other things, the Company's ability to find one or more purchasers'
willing to purchase the non-strategic assets at prices acceptable to the Company
and the purchasers' ability to complete the transaction. There can be no
assurances that the Company will be successful in completing the divestitures in
1999 or in 2000.
 
     The Company anticipates that it will continue to sell non-strategic
properties from time to time to increase capital resources available for other
activities, to achieve operating and administrative efficiencies and to improve
profitability.
 
ACQUISITION ACTIVITIES
 
     GENERAL. The Company regularly seeks to acquire properties that complement
its operations and provide further development opportunities and cost-reduction
potential. In addition, the Company pursues strategic acquisitions that will
allow the Company to expand into new geographical areas that feature producing
properties and provide development or exploration opportunities. During 1998,
the Company reduced its emphasis on major acquisitions and, instead,
concentrated its efforts on maximizing the value of the properties acquired in
1997. During 1997, the Company completed three major transactions: the merger
with Mesa for total consideration of $991.0 million, the acquisition of Chauvco
for total consideration of $721.4 million and the acquisition of assets from
America Cometra for total consideration of $130 million. These acquisitions
added significantly to the Company's exploratory and development drilling
opportunities, balanced the Company's reserve mix between oil and natural gas,
increased the scale of its operations in the Mid Continent region, the offshore
Gulf Coast region, Argentina and Canada and provided the Company with a
significant base of operations and experienced personnel for its areas of
geographic focus, including international areas. During 1996, the Company
focused on smaller acquisitions of properties that exhibited one or more of the
following characteristics: properties that were near or otherwise complemented
the Company's existing properties, properties that represented additional
working interests in Company-operated properties or properties that provided the
Company with strategic exploitation or exploration opportunities. In 1996,
aggregate expenditures to acquire such interests and properties amounted to
approximately $21 million.
 
     FUTURE ACQUISITION OPPORTUNITIES. The Company regularly pursues and
evaluates acquisition opportunities (including opportunities to acquire
particular oil and gas properties or related assets or entities owning oil and
gas properties or related assets and opportunities to engage in mergers,
consolidations or other business
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<PAGE>   7
 
combinations with such entities) and at any given time may be in various stages
of evaluating such opportunities. Such stages may take the form of internal
financial analysis, oil and gas reserve analysis, due diligence, the submission
of an indication of interest, preliminary negotiations, negotiation of a letter
of intent or negotiation of a definitive agreement.
 
FINANCIAL MANAGEMENT
 
     The Company strives to maintain its outstanding indebtedness at a moderate
level in order to provide sufficient financial flexibility for future
exploration, development and acquisition opportunities. While the Company may
occasionally incur higher levels of debt to take advantage of opportunities,
management's objective is to maintain a flexible capital structure and to
strengthen the Company's financial position through debt management.
 
     As with any organization, the Company has experienced various debt levels
in recent years as it has responded to strategic opportunities. During 1996 and
1995, the Company took deliberate actions to reduce its debt levels or extend
its debt maturities in order to improve its financial flexibility and enable it
to take advantage of future strategic opportunities. The Company was able to
reduce its debt level significantly each year through the application of
proceeds from the dispositions of assets that the Company had identified as
non-strategic (see "Asset Divestitures" above). In 1997, the Company's debt
level increased as a result of the assumption of the debt of Mesa and Chauvco.
In 1998, severe commodity price declines reduced cash flows from operating
activities, causing the Company to increase debt to finance committed capital
investments. As a result of the increases in debt and reductions in
shareholders' equity primarily resulting from 1998 and 1997 non-cash asset
impairment provisions (see Note M and Note O of Notes to Consolidated Financial
Statements included in "Item 8. Financial Statements and Supplementary Data"),
the Company's debt as a percentage of total capitalization has increased to 73
percent and 56 percent at December 31, 1998 and 1997, respectively. In 1999, the
Company intends, as it did in 1996 and 1995, to take deliberate actions to
reduce debt through reductions in capital investments and the use of operating
cash flows and net proceeds from the divestiture of non-strategic assets.
 
MARKETING OF PRODUCTION
 
     GENERAL. Production from the Company's properties is marketed consistent
with industry practices. Sales prices for both oil and gas production are
negotiated based on factors normally considered in the industry such as the spot
price for gas or the posted price for oil, price regulations, distance from the
well to the pipeline, well pressure, estimated reserves, commodity quality and
prevailing supply conditions.
 
     SIGNIFICANT PURCHASERS. During 1998, the Company's primary purchaser of
crude oil was Genesis Crude Oil L.P. ("Genesis") and the Company's primary
purchaser of natural gas liquids was Williams Energy Services ("Williams").
Approximately 10 percent and 10 percent of the Company's 1998 oil and gas
revenues were attributable to sales to Genesis and Williams, respectively.
During 1998, the Company marketed its natural gas to a variety of purchasers,
none of which accounted for 10 percent or more of the Company's oil and gas
revenues. The Company is of the opinion that the loss of any one purchaser would
not have an adverse effect on its ability to sell its oil and gas production or
natural gas products.
 
     HEDGING ACTIVITIES. The Company periodically enters into commodity
derivative contracts (swaps, futures and options) in order to (i) reduce the
effect of the volatility of price changes on the commodities the Company
produces and sells, (ii) support the Company's annual capital budgeting and
expenditure plans and (iii) lock in prices to protect the economics related to
certain capital projects.
 
     See "Item 7. Management's Discussion and Analysis of Financial Condition
and Results of Operations" for a description of the Company's results of its
hedging activities; "Item 7A. Quantitative and Qualitative Disclosures About
Market Risk" for discussions regarding the hedging strategies used by the
Company to mitigate commodity price risks associated with crude oil, natural gas
liquids and natural gas sales; and Note J of Notes to Consolidated Financial
Statements included in "Item 8. Financial Statements and Supplementary Data" for
a description of the Company's open hedge positions at December 31, 1998 and the
related prices to be realized.
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<PAGE>   8
 
OPERATIONS BY GEOGRAPHIC AREA
 
     The Company operates in one industry segment. During 1998, the Company
principally had oil and gas producing activities in the United States, Canada
and Argentina and had exploration activities primarily in the United States,
Canada, Argentina and South Africa. During 1997 and 1996, prior to the
acquisition of Chauvco, the Company did not have significant operations in
geographic areas other than the United States. See Note P of Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data" for geographic operating segment information.
 
COMPETITION, MARKETS AND REGULATION
 
     COMPETITION. The oil and gas industry is highly competitive. A large number
of companies and individuals engage in the exploration for and development of
oil and gas properties, and there is a high degree of competition for oil and
gas properties suitable for development or exploration. Acquisitions of oil and
gas properties have been an important element of the Company's growth, and the
Company intends to continue to acquire oil and gas properties. The principal
competitive factors in the acquisition of oil and gas properties include the
staff and data necessary to identify, investigate and purchase such properties
and the financial resources necessary to acquire and develop them. Many of the
Company's competitors are substantially larger and have financial and other
resources greater than those of the Company.
 
     MARKETS. The Company's ability to produce and market oil and gas profitably
depends on numerous factors beyond the Company's control. The effect of these
factors cannot be accurately predicted or anticipated. In recent years,
worldwide oil and gas production capacities in certain areas of the United
States have exceeded demand, with resulting declines in the price of oil and
gas. Although the Company cannot predict the occurrence of events that may
affect oil and gas prices or the degree to which oil and gas prices will be
affected, it is possible that prices for any oil or gas the Company produces
will be equivalent to or lower than those currently available. A continuation of
the current commodity price environment or a further decline in the price of oil
or gas will continue to adversely affect the Company's revenues, profitability
and cash flow.
 
     During most of 1996 and 1997, the Company benefited from higher oil prices
as compared to previous years. However, during the fourth quarter of 1997, oil
prices began a downward trend that has continued through March 1999. A
continuation of the present oil price environment will prolong the associated
adverse effect on the Company's revenues and operating cash flow, and may result
in further downward adjustments to the Company's current 1999 capital budget of
$100 million. Additionally, declines in the outlook for future price levels have
contributed to 1998 and 1997 non-cash impairment provisions to reduce the
carrying values of oil and gas properties and in a non-cash valuation adjustment
to the Company's deferred tax assets. See Note M and Note O of Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data" for specific disclosures relative to the impairments and
valuation provisions. Continued declines in commodity prices could result in
additional impairment or valuation provisions in the future.
 
     GOVERNMENTAL REGULATION. Oil and gas exploration and production are subject
to various types of regulation by local, state, federal and foreign agencies.
The Company's operations are also subject to state conservation laws and
regulations, including provisions for the unitization or pooling of oil and gas
properties, the establishment of maximum rates of production from wells and the
regulation of spacing, plugging and abandonment of wells. Each state generally
imposes a production or severance tax with respect to production and sale of oil
and gas within their respective jurisdictions. The regulatory burden on the oil
and gas industry increases the Company's cost of doing business and,
consequently, affects its profitability.
 
     The Outer Continental Shelf Lands Act (the "OCSLA") requires that all
pipelines operating on or across the Outer Continental Shelf (the "OCS") provide
open-access, nondiscriminatory service. Although the Federal Energy Regulatory
Commission ("FERC") has chosen not to impose the regulations of Order No. 509,
which implements the OCSLA, on gatherers and other non-jurisdictional entities,
FERC has retained the authority to exercise jurisdiction over those entities if
necessary to permit nondiscriminatory access to service on the OCS. In addition,
gathering lines are currently exempt from FERC's jurisdiction, regardless of
whether they are on the OCS, but FERC could eliminate this exception. Commencing
                                        8
<PAGE>   9
 
May 1994, FERC issued a series of orders in individual cases that delineate its
current gathering policy. FERC's gathering policy was retained and clarified
with regard to deep water offshore facilities in a statement of policy issued in
February 1996. FERC's new gathering policy does not address its jurisdiction
over pipelines operating on or across the OCS pursuant to the OCSLA. If FERC
were to apply Order No. 509 to gatherers on the OCS, eliminate the exemption of
gathering lines and redefine its jurisdiction over gathering lines, these acts
could result in a reduction in available pipeline space for existing shippers in
the Gulf of Mexico and elsewhere, such as the Company.
 
     Additional proposals and proceedings that might affect the oil and gas
industry are considered from time to time by Congress, FERC, state regulatory
bodies, the courts and foreign governments. The Company cannot predict when or
if any such proposals might become effective or their effect, if any, on the
Company's operations.
 
     ENVIRONMENTAL AND HEALTH CONTROLS. The Company's operations are subject to
numerous federal, state, local and foreign laws and regulations relating to
environmental and health protection. These laws and regulations may require the
acquisition of a permit before drilling commences, restrict the type, quantities
and concentration of various substances that can be released into the
environment in connection with drilling and production activities, limit or
prohibit drilling activities on certain lands lying within wilderness, wetlands
and other protected areas and impose substantial liabilities for pollution
resulting from oil and gas operations. These laws and regulations may also
restrict air or other discharges resulting from the operation of natural gas
processing plants, pipeline systems and other facilities that the Company owns.
Although the Company believes that compliance with environmental laws and
regulations will not have a material adverse effect on its results of operations
or financial condition, risks of substantial costs and liabilities are inherent
in oil and gas operations, and there can be no assurance that significant costs
and liabilities, including potential criminal penalties, will not be incurred.
Moreover, it is possible that other developments, such as stricter environmental
laws and regulations or claims for damages to property or persons resulting from
the Company's operations, could result in substantial costs and liabilities.
 
     The Comprehensive Environmental Response, Compensation, and Liability Act
("CERCLA"), also known as the "Superfund" law, imposes liability, without regard
to fault or the legality of the original conduct, on certain classes of persons
with respect to the release of a "hazardous substance" into the environment.
These persons include the owner or operator of the disposal site or sites where
the release occurred and companies that disposed or arranged for the disposal of
hazardous substances released at the site. Persons who are or were responsible
for releases of hazardous substances under CERCLA may be subject to joint and
several liability for the costs of cleaning up the hazardous substances that
have been released into the environment and for damages to natural resources,
and it is not uncommon for neighboring landowners and other third parties to
file claims for personal injury and property damage allegedly caused by the
hazardous substances released into the environment.
 
     The Company generates wastes, including hazardous wastes, that are subject
to the federal Resource Conservation and Recovery Act ("RCRA") and comparable
state statutes. The U.S. Environmental Protection Agency and various state
agencies have limited the approved methods of disposal for certain hazardous and
non-hazardous wastes. Furthermore, certain wastes generated by the Company's oil
and natural gas operations that are currently exempt from treatment as
"hazardous wastes" may in the future be designated as "hazardous wastes," and
therefore be subject to more rigorous and costly operating and disposal
requirements.
 
     The Company currently owns or leases, and has in the past owned or leased,
properties that for many years have been used for the exploration and production
of oil and gas. Although the Company has used operating and disposal practices
that were standard in the industry at the time, hydrocarbons or other wastes may
have been disposed of or released on or under the properties owned or leased by
the Company or on or under other locations where such wastes have been taken for
disposal. In addition, some of these properties have been operated by third
parties whose treatment and disposal or release of hydrocarbons or other wastes
was not under the Company's control. These properties and the wastes disposed
thereon may be subject to CERCLA, RCRA and analogous state laws. Under such
laws, the Company could be required to remove or
 
                                        9
<PAGE>   10
 
remediate previously disposed wastes or property contamination or to perform
remedial plugging operations to prevent future contamination.
 
     Federal regulations require certain owners or operators of facilities that
store or otherwise handle oil, such as the Company, to prepare and implement
spill prevention control plans, countermeasure plans, and facility response
plans relating to the possible discharge of oil into surface waters. The Oil
Pollution Prevention Act of 1990 ("OPA") amends certain provisions of the
federal Water Pollution Control Act of 1972, commonly referred to as the Clean
Water Act ("CWA") and other statutes as they pertain to the prevention of and
response to oil spills into navigable waters. The OPA subjects owners of
facilities to strict joint and several liability for all containment and cleanup
costs and certain other damages arising from a spill, including, but not limited
to, the costs of responding to a release of oil to surface waters. The CWA
provides penalties for any discharges of petroleum products in reportable
quantities and imposes substantial liability for the costs of removing a spill.
State laws for the control of water pollution also provide varying civil and
criminal penalties and liabilities in the case of releases of petroleum or its
derivatives into surface waters or into the ground.
 
     OPA requires responsible parties to establish and maintain evidence of
financial responsibility to cover removal costs and damages resulting from an
oil spill. OPA calls for a financial responsibility increase from $35 million to
$150 million to cover pollution cleanup for offshore facilities. In August 1993,
the United States Mineral Management Service (the "MMS"), which has been charged
with implementing certain segments of OPA, issued its advanced notice of
proposed rulemaking that would increase financial responsibility requirements
for offshore lessees and permittees to $150 million as required by OPA. Due to
the OPA's broad definition of "offshore facility," the Company could become
subject to the financial responsibility rule if it is proposed and adopted; to
date, however, the MMS has not formally proposed the financial responsibility
regulations. On May 9, 1995, the U.S. House of Representatives passed a bill
that would lower the financial responsibility requirements applicable to
offshore facilities to $35 million (the current requirement under the federal
OCSLA). The bill allows the limit to be increased to $150 million if a formal
risk assessment indicates the increase to be warranted. It would also define
"offshore facility" to include only coastal oil and gas properties. A U.S.
Senate bill that would also lower the financial responsibility requirements for
offshore facilities was passed in late 1995. The Senate bill would reduce the
scope of "offshore facilities" subject to this financial assurance requirement
to those facilities seaward of the U.S. coastline that are engaged in drilling
for, producing or processing oil or that have the capacity to transport, store,
transfer, or handle more than 1,000 barrels of oil at a time. Currently, the
House and Senate bills are being reconciled in Conference Committee. The Clinton
Administration has indicated support for these changes to the OPA financial
responsibility requirements. The Company cannot predict the final form of the
financial responsibility requirements that will be ultimately established, but
any role that requires the Company to establish evidence of financial
responsibility in the amount of $150 million has the potential to have a
material adverse effect on the Company's results of operations and financial
condition. The Company does not believe that the rule to be proposed by the MMS
will be any more burdensome to it than it will be to other similarly situated
oil and gas companies.
 
     Many states in which the Company operates have recently begun to regulate
naturally occurring radioactive materials ("NORM") and NORM wastes that are
generated in connection with oil and gas exploration and production activities.
NORM wastes typically consist of very low-level radioactive substances that
become concentrated in pipe scale and in production equipment. State regulations
may require the testing of pipes and production equipment for the presence of
NORM, the licensing of NORM-contaminated facilities and the careful handling and
disposal of NORM wastes. The Company believes that the growing regulation of
NORM will have a minimal effect on the Company's operations because the Company
generates only a very small quantity of NORM on an annual basis.
 
     The Company does not believe that its environmental risks are materially
different from those of comparable companies in the oil and gas industry.
Nevertheless, no assurance can be given that environmental laws will not, in the
future, result in a curtailment of production or processing or a material
increase in the costs of production, development, exploration or processing or
otherwise adversely affect the Company's results of operations and financial
condition.
 
                                       10
<PAGE>   11
 
     The Company employs an environmental specialist charged with monitoring
regulatory compliance. The Company performs an environmental review as part of
the due diligence work on potential acquisitions, including acquisitions of oil
and gas properties. The Company is not aware of any material environmental legal
proceedings pending against it or any significant environmental liabilities to
which it may be subject.
 
RISKS ASSOCIATED WITH BUSINESS ACTIVITIES
 
     The nature of the business activities conducted by the Company subjects it
to certain hazards and risks. The following is a summary of some of the material
risks relating to the Company's business activities.
 
     OIL AND GAS PRICES AND GENERAL MARKET RISKS. The Company's revenues,
profitability, cash flow and future rate of growth are highly dependent on
prices of oil and gas, which are affected by numerous factors beyond the
Company's control. Oil and gas prices historically have been very volatile. A
continuation of the significantly lower oil and gas prices experienced in 1998,
as compared to prior years, or a further decline in the prices of oil or gas
will have a material adverse effect on the Company's revenues, profitability and
cash flow and could, under certain circumstances, result in a reduction in the
carrying value of the Company's oil and gas properties, a valuation adjustment
to the Company's deferred tax assets and a reduction in the Company's
commitments under its bank credit facilities.
 
     RISKS OF DRILLING ACTIVITIES. As noted under "Item 1. Business -- Business
Activities," of the total 1999 capital budget of $100 million, the Company
anticipates spending approximately $75 million on development activities and $25
million on exploration activities. Drilling involves numerous risks, including
the risk that no commercially productive natural gas or oil reservoirs will be
encountered. The cost of drilling, completing and operating wells is often
uncertain and drilling operations may be curtailed, delayed or canceled as a
result of a variety of factors, including unexpected drilling conditions,
pressure or irregularities in formations, equipment failures or accidents,
adverse weather conditions and shortages or delays in the delivery of equipment.
The Company's future drilling activities may not be successful and, if
unsuccessful, such failure could have an adverse effect on the Company's future
results of operations and financial condition. While all drilling, whether
developmental or exploratory, involves these risks, exploratory drilling
involves greater risks of dry holes or failure to find commercial quantities of
hydrocarbons. Because of the percentage of the Company's capital budget devoted
to exploratory projects, it is likely that the Company will continue to
experience exploration and abandonment expense.
 
     RISKS ASSOCIATED WITH UNPROVED PROPERTIES. At December 31, 1998 and 1997,
the Company had unproved property costs of $342.6 million and $545.1 million,
respectively. United States generally accepted accounting principles require
periodic evaluation of these costs on a project-by-project basis in comparison
to their estimated value. These evaluations will be affected by results of
exploration activities, commodity price outlooks, planned future sales or
expiration of all or a portion of such projects. If the quantity of potential
reserves determined by such evaluations are not sufficient to fully recover the
cost invested in each project, the Company may be required to recognize
significant non-cash charges in the earnings of future periods. There can be no
assurance that economic reserves will be determined to exist for such projects.
 
     ACQUISITIONS. Acquisitions of producing oil and gas properties have been a
key element of the Company's growth. The Company's growth following the full
development of its existing property base could be impeded if it is unable to
acquire additional oil and gas properties on a profitable basis. The success of
any acquisition will depend on a number of factors, including the ability to
estimate accurately the recoverable volumes of reserves, rates of future
production and future net revenues attributable to reserves and to assess
possible environmental liabilities. All of these factors affect whether an
acquisition will ultimately generate cash flows sufficient to provide a suitable
return on investment. Even though the Company performs a review of the
properties it seeks to acquire that it believes is consistent with industry
practices, such reviews are often limited in scope.
 
     DIVESTITURES. The Company regularly reviews its property base for the
purpose of identifying non-strategic assets, the disposition of which would
increase capital resources available for other activities and create
organizational and operational efficiencies. Various factors could materially
affect the ability of the
 
                                       11
<PAGE>   12
 
Company to dispose of non-strategic assets, including the availability of
purchasers willing to purchase the non-strategic assets at prices acceptable to
the Company.
 
     RISKS ASSOCIATED WITH OPERATION OF NATURAL GAS PROCESSING PLANTS. The
Company owns interests in seven natural gas processing plants and operates three
of those plants, although the net revenues derived from natural gas processing
during 1998 and 1997 represented only one percent of the total net revenues from
oil and gas activities. There are significant risks associated with the
operation of natural gas processing plants. Natural gas and natural gas liquids
are volatile and explosive and may include carcinogens. Damage to or
misoperation of a natural gas processing plant could result in an explosion or
the discharge of toxic gases, which could result in significant damage claims in
addition to interrupting a revenue source.
 
     OPERATING HAZARDS AND UNINSURED RISKS. The Company's operations are subject
to all the risks normally incident to the oil and gas exploration and production
business, including blowouts, cratering, explosions and pollution and other
environmental damage, any of which could result in substantial losses to the
Company due to injury or loss of life, damage to or destruction of wells,
production facilities or other property, clean-up responsibilities, regulatory
investigations and penalties and suspension of operations. Although the Company
currently maintains insurance coverage that it considers reasonable and that is
similar to that maintained by comparable companies in the oil and gas industry,
it is not fully insured against certain of these risks, either because such
insurance is not available or because of high premium costs.
 
     ENVIRONMENTAL RISKS. The oil and gas business is also subject to
environmental hazards, such as oil spills, gas leaks and ruptures and discharges
of toxic substances or gases that could expose the Company to substantial
liability due to pollution and other environmental damage. A variety of federal,
state and foreign laws and regulations govern the environmental aspects of the
oil and gas business. Noncompliance with these laws and regulations may subject
the Company to penalties, damages or other liabilities, and compliance may
increase the cost of the Company's operations. Such laws and regulations may
also affect the costs of acquisitions. See "Item 1. Business -- Competition,
Markets and Regulation -- Environmental and Health Controls".
 
     The Company does not believe that its environmental risks are materially
different from those of comparable companies in the oil and gas industry.
Nevertheless, no assurance can be given that environmental laws will not, in the
future, result in a curtailment of production or processing or a material
increase in the costs of production, development, exploration or processing or
otherwise adversely affect the Company's operations and financial condition.
Pollution and similar environmental risks generally are not fully insurable.
 
     COMPETITION. The oil and gas industry is highly competitive. The Company
competes with other companies, producers and operators for acquisitions and in
the exploration, development, production and marketing of oil and gas. Some of
these competitors have substantially greater financial and other resources than
the Company. See "Item 1. Business -- Competition, Markets and Regulation".
 
     RISKS ASSOCIATED WITH DEBT. At December 31, 1998 and 1997, the Company had
total debt outstanding of $2.2 billion and $1.9 billion, respectively. As of
December 31, 1998, approximately 55 percent of the Company's total debt was
comprised of variable rate debt that is sensitive to changes in market interest
rates. Such variable rate debt is primarily comprised of borrowings under credit
facilities. During 1999, the Company must reduce its borrowings by $306.5
million to comply with commitment reduction provisions specified in the credit
facilities and other current debt obligations. The Company is also subject to
certain debt covenants that are defined in the credit facilities. See "Interest
rate sensitivity" included in "Item 7A. Quantitative and Qualitative Disclosures
About Market Risk" for additional information regarding the Company's risks
associated interest rate sensitivity. Also, see "1999 Outlook -- Credit
facilities" included in "Item 7. Managements' Discussion and Analysis of
Financial Condition and Results of Operations" and Note E of Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data" for discussions relative to the Company's credit facilities.
 
     GOVERNMENT REGULATION. The Company's business is regulated by a variety of
federal, state, local and foreign laws and regulations. There can be no
assurance that present or future regulations will not adversely
 
                                       12
<PAGE>   13
 
affect the Company's business and operations. See "Item 1.
Business -- Competition, Markets and Regulation".
 
     RISKS OF INTERNATIONAL OPERATIONS. At December 31, 1998, approximately 22
percent of the Company's proved reserves of oil and gas were located outside the
United States (14 percent in Argentina and 8 percent in Canada). The success and
profitability of international operations may be adversely affected by risks
associated with international activities, including economic and labor
conditions, political instability, tax laws (including U.S. taxes on foreign
subsidiaries) and changes in the value of the United States dollar versus the
local currency in which oil and gas are sold. To the extent that the Company is
involved in international activities, changes in exchange rates may adversely
affect the Company's consolidated revenues and expenses (as expressed in United
States dollars).
 
     ESTIMATES OF RESERVES AND FUTURE NET REVENUES. Numerous uncertainties exist
in estimating quantities of proved reserves and future net revenues therefrom.
The estimates of proved reserves and related future net revenues set forth in
this Report are based on various assumptions, which may ultimately prove to be
inaccurate. Therefore, such estimates should not be construed as estimates of
the current market value of the Company's proved reserves.
 
DEFINITION OF CERTAIN OIL AND GAS TERMS
 
     When used in this Report, the following terms have the meanings indicated
below.
 
     "Bbl" means a standard barrel of 42 U.S. gallons and represents the basic
unit for measuring the production of crude oil, natural gas liquids and
condensate.
 
     "Bcf" means one billion cubic feet.
 
     "Bcfe" means a billion cubic feet equivalent and is a customary convention
used in the United States to express oil and gas volumes on a comparable basis.
It is determined on the basis of the estimated relative energy content of oil to
natural gas, being approximately one barrel of oil per six Mcf of gas.
 
     "BOE" means a barrel-of-oil-equivalent and is a customary convention used
in the United States to express oil and gas volumes on a comparable basis. It is
determined on the basis of the estimated relative energy content of natural gas
to oil, being approximately six Mcf of natural gas per Bbl of oil.
 
     "Btu" means British thermal unit and represents the amount of heat needed
to raise the temperature of one pound of water one degree Fahrenheit.
 
     "gross" acre or well means an acre or well in which a working interest is
owned.
 
     "MBbl" means one thousand Bbls.
 
     "MBOE" means one thousand BOEs.
 
     "Mcf" means one thousand cubic feet under prescribed conditions of pressure
and temperature and represents the basic unit for measuring the production of
natural gas.
 
     "MMcf" means one million cubic feet.
 
     "net" acres or wells is determined by multiplying the gross acres or wells,
as the case may be, by the applicable working interest in those gross acres or
wells.
 
     "NGLs" means natural gas liquids.
 
     "NYMEX" means The New York Mercantile Exchange.
 
     "proved reserves" means those estimated quantities of crude oil and natural
gas that geological and engineering data demonstrate with reasonable certainty
to be recoverable in future years from known oil and gas reservoirs under
existing economic and operating conditions. Proved reserves are limited to those
quantities of oil and gas that can be expected to be recoverable commercially at
current prices and costs, under existing regulatory practices and with existing
conventional equipment and operating methods.
 
                                       13
<PAGE>   14
 
     "PV 10 value" means the present value of estimated future net revenues,
before income taxes, of proved reserves, determined in all material respects in
accordance with the rules and regulations of the United States Securities and
Exchange Commission ("SEC") (generally using prices and costs in effect at the
specified date and a 10 percent discount rate). The reserve estimates for 1998
utilize an oil price of $10.09 per Bbl (reflecting adjustments for oil quality
and gathering and transportation costs), an NGL price of $6.81 per Bbl and a gas
price of $1.64 per Mcf (reflecting adjustments for Btu content, gathering and
transportation costs and gas processing and shrinkage).
 
ITEM 2. PROPERTIES
 
     The information included in this Report about the Company's proved oil and
gas reserves at December 31, 1998, including estimated quantities and PV 10
value, is based on reserve reports prepared by the Company's engineers.
 
     Numerous uncertainties exist in estimating quantities of proved reserves
and in projecting future rates of production and timing of development
expenditures, including many factors beyond the Company's control. This Report
contains estimates of the Company's proved oil and gas reserves and the related
future net revenues, which are based on various assumptions, including those
prescribed by the SEC. Actual future production, oil and gas prices, revenues,
taxes, capital expenditures, operating expenses, geologic success and quantities
of recoverable oil and gas reserves may vary substantially from those assumed in
the estimates and could materially affect the estimated quantities and related
PV 10 value of proved reserves set forth in this Report. In addition, the
Company's reserves may be subject to downward or upward revisions based on
production performance, purchases or sales of properties, results of future
development, prevailing oil and gas prices and other factors. Therefore,
estimates of the PV 10 value of proved reserves contained in this Report should
not be construed as estimates of the current market value of the Company's
proved reserves.
 
     PV 10 value is a reporting convention that provides a common basis for
comparing oil and gas companies subject to the rules and regulations of the SEC.
It requires the use of oil and gas prices prevailing as of the date of
computation. Consequently, it may not reflect the prices ordinarily received or
that will be received for oil and gas because of seasonal price fluctuations or
other varying market conditions. PV 10 values as of any date are not necessarily
indicative of future results of operations. Accordingly, estimates of future net
revenues in this Report may be materially different from the net revenues that
are ultimately received.
 
     The Company did not provide estimates of total proved oil and gas reserves
during 1998 to any federal authority or agency, other than the SEC.
 
PROVED RESERVES
 
     The Company's proved reserves totaled 676.8 million BOE at December 31,
1998, 761.6 million BOE at December 31, 1997 and 302.2 million BOE at December
31, 1996, representing $1.6 billion, $3.1 billion and $2.3 billion,
respectively, in PV 10 value. Downward revisions of reserve quantities as a
result of the decline in commodity prices was the primary reason for the
decrease in reserves and PV 10 value during 1998.
 
                                       14
<PAGE>   15
 
     On a BOE basis, 90 percent of the Company's total proved reserves at
December 31, 1998 are proved developed reserves. Based on reserve information as
of December 31, 1998 and using the Company's reserve report production
information for 1999, the reserve-to-production ratio associated with the
Company's proved reserves is 11 years on a BOE basis. The following table
provides information regarding the Company's proved reserves by geographic area
as of and for the year ended December 31, 1998.
 
                          PROVED OIL AND GAS RESERVES
 
<TABLE>
<CAPTION>
                                                                             1998 AVERAGE
                          PROVED RESERVES AS OF DECEMBER 31, 1998        DAILY PRODUCTION(a)
                         ------------------------------------------   --------------------------
                           OIL      NATURAL                PV 10       OIL     NATURAL
                         & NGLS       GAS                  VALUE      & NGLS     GAS
                         (MBbls)    (MMcf)      MBOE       (000)      (BBls)    (Mcf)      BOE
                         -------   ---------   -------   ----------   ------   -------   -------
<S>                      <C>       <C>         <C>       <C>          <C>      <C>       <C>
United States..........  269,638   1,545,644   527,246   $1,226,869   69,390   377,373   132,285
Argentina..............   24,219     428,334    95,608      232,799   9,041     73,427    21,279
Canada.................   12,447     249,230    53,985      189,140   9,852     53,072    18,697
                         -------   ---------   -------   ----------   ------   -------   -------
     Total.............  306,304   2,223,208   676,839   $1,648,808   88,283   503,872   172,261
                         =======   =========   =======   ==========   ======   =======   =======
</TABLE>
 
- ---------------
 
(a)  The 1998 average daily production is calculated using a 365-day year and
     without making pro forma adjustments for any acquisitions, divestitures or
     drilling activity that occurred during the year.
 
RESERVE REPLACEMENT
 
     For the first time in almost a decade, the Company was unable to replace
its annual production volumes with proved reserves of crude oil, NGLs and
natural gas, stated on an energy equivalent basis. During 1998, the Company's
proved reserves declined 84.8 million BOE including 62.9 million BOE related to
production, 31.2 million BOE related to downward reserve revisions and 2.5
million BOE related to asset sales. Discoveries and extensions of 11.8 million
BOE partially offset these reductions. Reserve revisions result from several
factors including changes in existing estimates of quantities available for
production and changes in estimates of quantities which are economical to
produce under current pricing conditions. The downward revisions in 1998 relate
primarily to the decline in commodity prices during 1998. The Company's reserves
as of December 31, 1998 were estimated using a price of $10.09 per Bbl of oil,
$6.81 per Bbl of NGLs and $1.64 per Mcf of gas. Should prices increase or
decline in future periods, reserves may be revised upward or downward for
quantities which may be economical or uneconomical to produce at higher or lower
prices, respectively.
 
     The Company's 1998 reserve replacement rate on a BOE basis was negative due
to the severe decline in commodity prices during 1998. Previous reserve
replacement performance rates were 1,450 percent in 1997 (1,375 percent for oil
and 1,528 percent for gas) and 314 percent in 1996 (398 percent for oil and 239
percent for gas). For the three-year period ended December 31, 1998, the average
reserve replacement rate was 465 percent, as compared to a three-year average
replacement rate of 769 percent in 1997 and 377 percent in 1996. During 1998,
the reserve replacement rate was primarily influenced by the decline in
commodity prices which resulted in significant downward reserve revisions.
During 1997, the Company's reserve replacement rate was primarily the product of
its acquisition activities. In 1996, the reserve replacement rate was influenced
primarily by exploration and development activities.
 
FINDING COST
 
     The Company's acquisition and finding cost per BOE for 1998 was negative as
compared to the 1997 and 1996 acquisition and finding costs of $8.23 and $3.10
per BOE, respectively. The negative rate in 1998 was a result of downward
reserve revisions related to the decline in commodity prices during 1998. The
rate in 1997 was a result of the fair value associated with Mesa's and Chauvco's
long-lived, low production cost reserves. The average acquisition and finding
cost for the three-year period from 1996 to 1998 was $8.65 per BOE representing
a 23 percent increase from the 1997 three-year average rate of $7.04.
 
                                       15
<PAGE>   16
 
OIL AND GAS MIX
 
     The Company seeks to maintain a strategic balance between oil and natural
gas reserves and production. While the Company's reserve and production mix may
vary somewhat on a short-term basis as the Company takes advantage of market
conditions and specific acquisition and development opportunities, management
believes that a relative mix of approximately 50 percent oil and NGLs and 50
percent natural gas is in the best long-term interests of the Company and its
stockholders. The Company's reserve mix was 45 percent oil and NGLs and 55
percent gas at December 31, 1998, and its production mix was 51 percent oil and
NGLs and 49 percent gas during 1998.
 
DESCRIPTION OF PROPERTIES
 
     As of December 31, 1998, the Company has operations in the United States,
Argentina and Canada, and to a lesser extent, exploration opportunities in
Africa.
 
     DOMESTIC. The Company's domestic operations are principally located in the
Gulf Coast, Mid Continent and Permian Basin areas. In the Gulf Coast area, the
Company is focused on reserve and production growth through a balanced portfolio
of development and exploration activities. To accomplish this, the Company has
devoted most of its domestic exploration efforts to this area, as well as its
investment in and utilization of 3-D seismic technology. During 1998, the
Company expended $167 million to drill 38 development and eight exploratory
wells and more importantly, significantly enhanced its library of seismic data
for future exploration activities.
 
     During 1999, the Company's exploration drilling will be concentrated in the
Gulf of Mexico and the onshore Gulf Coast area. The Company will participate in
the drilling of one or two wells in its deep-water Mississippi Canyon Block 305.
The Company has a 25 percent working interest (21.875 percent net revenue
interest) in the block; however, Pioneer is responsible for 50 percent of the
before casing point drilling costs in the first exploratory well drilled.
Drilling began on the first well in this block during January 1999. The well is
scheduled for preliminary evaluations in March. Two additional wells are planned
for 1999 onshore in the Gulf Coast area or in East Texas where several shallower
exploration prospects have been defined by the Company's 3-D database.
 
     The Mid Continent area includes properties located in Kansas, the Texas
Panhandle, Oklahoma and Arkansas. By far, the largest of these assets is the
Company's Hugoton field followed by the West Panhandle field, both acquired from
Mesa in August 1997. These two fields combined account for approximately $548
million of the Company's $1.6 billion of PV 10 reserve value at December 31,
1998. During 1998, the Company spent approximately $26 million on exploratory
and development drilling in the Mid Continent area. This activity included the
drilling of 89 development wells and two exploratory wells.
 
     Hugoton field. The Hugoton field in southwest Kansas is one of the largest
producing gas fields in the continental United States. The Company's Hugoton
properties represent approximately 13 percent of the proved reserves in the
field and are located on over 237,000 net acres, covering approximately 400
square miles. The Company has working interest in approximately 1,200 wells in
the Hugoton field, almost 1,000 of which it operates, and royalty interest in
approximately 750 wells. The Company owns substantially all of the gathering and
processing facilities, primarily the Satanta plant, that service its production
from the Hugoton field. Such ownership allows the Company to control the
production, gathering, processing and sale of its gas and associated NGLs.
 
     Production in the Hugoton field is subject to allowables set by state
regulators, but the Company's Hugoton operated properties are capable of
producing approximately 150 MMcf of wet gas per day (i.e., gas production at the
wellhead before processing and before reduction for royalties). The Company
estimates that it and other major producers in the Hugoton field produced at or
near capacity in 1998.
 
     The Company is considering plans to submit an application to the Kansas
Corporation Commission (the "KCC") to allow infill drilling into the Council
Grove Formation. The Company believes that such infill drilling could increase
production from its Hugoton properties. There can be no assurance that the
application will be approved or as to the timing of receipt of such approval if
such approval is obtained.
                                       16
<PAGE>   17
 
     West Panhandle field. The West Panhandle properties are located in the
panhandle region of Texas where initial production commenced in 1918. These
stable, long-lived reserves are attributable to the Red Cave, Brown Dolomite,
Granite Wash and fractured Granite formations at depths no greater than 3,500
feet. The Company's natural gas in the West Panhandle field is produced from
approximately 600 wells on more than 241,000 gross (185,000 net) acres covering
over 375 square miles. The Company's wellhead gas produced from the West
Panhandle field contains a high quantity of NGLs, yielding relatively greater
NGL volumes than realized from many other natural gas fields. The Company
operates the wells and production equipment and Colorado Interstate Gas Company
owns and operates the gathering system.
 
     The production from the West Panhandle field is processed through the
Company-owned Fain natural gas processing plant. In February 1997, the Company
initiated a project to add nitrogen rejection capabilities at the Fain Plant.
This project, which was completed in mid-1998, allows the Company to recover a
greater percentage of the helium in the processed gas; increase NGL recoveries;
and upgrade residue quality improving marketing flexibility.
 
     As of December 31, 1998, the Company's West Panhandle properties
represented approximately 13 percent of the Company's equivalent proved reserves
and approximately nine percent of the present value of estimated future net cash
flows, determined in accordance with SEC guidelines. The Company has identified
over 70 locations that have additional production potential that the Company
plans to redrill in the next few years.
 
     Since the early 1960's, the Company has been involved in acquisition and
development activities in fields in the Permian Basin area which includes all of
West Texas and Southeastern New Mexico. Of the $411 million of PV 10 value
contained in the properties in the Permian Basin area, the Spraberry field
accounts for $294 million. Along with the Spraberry field, the Iatan field in
Mitchell County, Texas, the Dagger Draw field in Eddy County, New Mexico and the
Ozona field in Crockett and Sutton Counties of Texas are significant to the
Company's Permian Basin area's operations in terms of existing production,
production and reserve growth, and identification of additional drilling
locations.
 
     The Company will continue to focus on the development of the existing
properties utilizing waterflood procedures and secondary recovery technologies
as these efforts have consistently resulted in increased production, reserve
additions due to development drilling, and new drilling locations. In addition,
all of the fields in this operational group have been screened for feasibility
for carbon dioxide (CO(2)) flood implementation. During 1998, the Company
expended $113 million to drill 271 development and 13 exploratory wells. Wells
being drilled at the end of 1998 are being shut-in temporarily in anticipation
of future increases in oil prices. When this takes place, the Company will be in
a position to increase its oil production rather quickly. In addition, the
Company anticipates spending $9 million in 1999 in the Permian Basin area to
drill approximately 50 wells which will also be shut-in temporarily pending
future increases in oil prices. Development activities will account for the
majority of these planned expenditures.
 
     Spraberry field. The Spraberry field was discovered in 1949 and encompasses
eight counties in West Texas. The field is approximately 150 miles long and 75
miles wide at its widest point. The oil produced is West Texas Intermediate
Sweet, and the gas produced is casinghead gas with an average Btu content of
1,400 Btu per Mcf. The oil and gas is produced from three formations, the upper
and lower Spraberry and the Dean, at depths ranging from 6,700 feet to 9,200
feet. The center of the Spraberry field was unitized in the late 1950's and
early 1960's by the major oil companies; however, until the late 1980's there
was very limited development activity in the field. Since 1989, the Company has
focused acquisition and development drilling activities in the unitized portion
of the Spraberry field due to the dormant condition of the properties and the
high net revenue interests available. The Company believes the area offers
excellent opportunities to enhance oil and gas reserves because of the hundreds
of undeveloped infill drilling locations and the ability to reduce operating
expenses through economies of scale. The Company initiated an aggressive
optimization and automation cost cutting program in 1998, which reduced
operating expenses. This program will continue in 1999 and the Company believes
that an additional 10 percent reduction can be achieved. In February 1997, the
Texas Railroad Commission (which regulates oil and gas production) entered a
favorable order on the
 
                                       17
<PAGE>   18
 
Company's application to allow administrative approval of uncontested
applications to increase the density of drilling in the Spraberry field from one
well per 80 acres to one well per 40 acres.
 
     INTERNATIONAL. The acquisition of Chauvco provided the Company with a
significant presence in Argentina and Canada, representing 14 percent and 11
percent, respectively, of the Company's PV 10 value at December 31, 1998. The
Company's Argentine properties are primarily located in the Tierra del Fuego and
Neuquen basins. The Company's share of Argentine production during 1998 averaged
21.3 MBOE's per day. The Tierra del Fuego production concession is located in
the extreme southern portion of Argentina, approximately 1,500 miles south of
the country's capital, Buenos Aires. Crude oil, natural gas, condensate and NGLs
are produced from six separate fields in which the Company has a 35 percent
working interest. Recent expansion of gas processing facilities and completed
pipeline connections at Tierra del Fuego will allow handling of increased
production volumes committed for delivery under a gas contract to a
petrochemical plant in Chile. Natural gas deliveries under the contract to the
methanol plant in Chile averaged 50 MMcf per day during 1998.
 
     The Company's operated production in Argentina is concentrated in the
Neuquen Basin which is located about 925 miles southwest of the country's
capital city and just to the east of the Andes Mountains. Crude oil and natural
gas are produced from the Loma Negra/NI Block, the Dadin Block, the Al Norte de
la Dorsal Block and the Neuquen del Medio Block in which the Company has a 100
percent working interest. A commercial discovery was made in the newly acquired
Bajo Baguales Block in which the Company has a 65 percent interest.
 
     During 1998, the Company drilled 46 development wells and 22 exploratory
wells in Argentina. The Company plans to spend $24 million on gas development
opportunities in Argentina during 1999.
 
     The Company's Canadian producing properties are primarily located in
Alberta and British Columbia, Canada in the following areas: Chinchaga, Martin
Creek, Thompson Lake/Alliance, Rycroft, Lookout Butte and David. During 1998,
these properties produced an average of 18.7 MBOE's per day, net to the
Company's interest. In addition, during 1998 the Company drilled 60 development
wells and 14 exploratory wells primarily in Chinchaga and Martin Creek areas.
These properties currently include 29 new development well locations that are
scheduled to be drilled in 1999.
 
     In addition to the proved producing assets of Chauvco and Mesa, the Company
acquired a substantial inventory of unproved oil and gas properties during 1997
which will provide the Company with many exploration opportunities with the
potential for significant reserve additions. Although the acquisition of a
portfolio of unproved properties represents an exciting challenge to the
Company's team of engineers, geologists and geophysicists, such opportunities
are not without risk. United States generally accepted accounting principles
require periodic evaluation of these costs on a project-by-project basis in
comparison to their estimated value. During 1998, the Company reduced the
carrying value of its unproved oil and gas properties by $147.3 million. See
Note M of Notes to Consolidated Financial Statements in "Item 8. Financial
Statements and Supplementary Data". An unproved property may be impaired if the
Company does not intend to drill the prospect as a result of downward revisions
to potential proved reserves, if the results of exploration or the Company's
outlook for future commodity prices indicate that the potential reserves are not
sufficient to generate net cash flows to recover the investment required by the
project, or if the Company intends to sell the property for less than its
carrying value. There can be no assurance that economic reserves will be
determined to exist for such projects in the future.
 
     On a smaller scale, the Company has entered into agreements to explore in
the African nations of South Africa and Gabon. The South African agreements
cover over 13 million acres along the southern coast of South Africa, generally
in water depths less than 650 feet. During 1998, the Company participated in the
drilling of five wells in South Africa. Of the five wells drilled, two
discovered hydrocarbons; however, future activities associated with these
discoveries is under evaluation given the current economic environment of the
oil and gas industry. In 1998, the Company incurred $16.0 million of drilling
and seismic costs in South Africa. During 1999, the Company has targeted both
South Africa and Gabon for comprehensive studies that will focus on analysis,
ranking and timing of prospects. No new wells are planned during 1999 in South
Africa
 
                                       18
<PAGE>   19
 
while the Company evaluates farmout and other risk sharing opportunities.
Seismic studies are currently planned to commence in Gabon during late 1999 or
early 2000.
 
SELECTED OIL AND GAS INFORMATION
 
     The following tables set forth selected oil and gas information for the
Company as of and for each of the years ended December 31, 1998, 1997 and 1996.
Because of normal production declines, increased or decreased drilling
activities and the effects of future acquisitions or divestitures, the
historical information presented below should not be interpreted as indicative
of future results.
 
     PRODUCTION, PRICE AND COST DATA. The following table sets forth production,
price and cost data with respect to the Company's properties for the years ended
December 31, 1998, 1997 and 1996.
 
                       PRODUCTION, PRICE AND COST DATA(a)
<TABLE>
<CAPTION>
                                                            YEAR ENDED DECEMBER 31,
                                  ---------------------------------------------------------------------------
                                                    1998                                   1997
                                  -----------------------------------------   -------------------------------
 
                                   UNITED                                      UNITED
                                   STATES    ARGENTINA   CANADA     TOTAL      STATES    ARGENTINA    TOTAL
                                  --------   ---------   -------   --------   --------   ---------   --------
<S>                               <C>        <C>         <C>       <C>        <C>        <C>         <C>
Production information:
 Annual production:
   Oil (MBbls)..................    15,167      3,072      3,315     21,554     13,470       148       13,618
   NGLs (MBbls).................    10,160        228        281     10,669      4,267        --        4,267
   Gas (MMcf)...................   137,741     26,801     19,371    183,913    104,868        --      104,868
   Total (MBOE).................    48,284      7,767      6,824     62,875     35,215       148       35,363
 Average daily production:
   Oil (Bbls)...................    41,555      8,415      9,082     59,052     36,903       406       37,309
   NGLs (Bbls)..................    27,835        626        770     29,231     11,691        --       11,691
   Gas (Mcf)....................   377,373     73,427     53,072    503,872    287,309        --      287,309
   Total (BOE)..................   132,285     21,279     18,697    172,261     96,479       406       96,885
 Average prices:
   Oil (per Bbl)................  $  13.96    $ 11.00    $ 10.96   $  13.08   $  18.50    $19.68     $  18.51
   NGLs (per Bbl)...............  $   8.86    $  9.83    $  9.54   $   8.90   $  12.59    $   --     $  12.59
   Gas (per Mcf)................  $   2.01    $  1.09    $  1.45   $   1.82   $   2.20    $   --     $   2.20
   Revenue (per BOE)............  $  11.99    $  8.40    $  9.83   $  11.32   $  15.16    $19.68     $  15.18
 Average costs:
   Production costs (per BOE):
     Lease operating expense....  $   3.04    $  2.57    $  3.56   $   3.04   $   3.01    $ 5.47     $   3.02
     Production taxes...........       .50        .15         --        .40        .81       .19          .81
     Workovers..................       .14         --        .10        .12        .25        --          .25
                                  --------    -------    -------   --------   --------    ------     --------
       Total....................  $   3.68    $  2.72    $  3.66   $   3.56   $   4.07    $ 5.66     $   4.08
   Depletion expense (per BOE)..  $   4.96    $  5.42    $  5.95   $   5.13   $   5.77    $ 8.70     $   5.78
 
<CAPTION>
                                       YEAR ENDED DECEMBER 31,
                                  ----------------------------------
                                                 1996
                                  ----------------------------------
                                             AUSTRALIA(b)
                                   UNITED        AND
                                   STATES     ARGENTINA      TOTAL
                                  --------   ------------   --------
<S>                               <C>        <C>            <C>
Production information:
 Annual production:
   Oil (MBbls)..................    10,872         403        11,275
   NGLs (MBbls).................        --          --            --
   Gas (MMcf)...................    73,924       1,927        75,851
   Total (MBOE).................    23,193         723        23,916
 Average daily production:
   Oil (Bbls)...................    29,705       1,100        30,805
   NGLs (Bbls)..................        --          --            --
   Gas (Mcf)....................   201,979       5,265       207,244
   Total (BOE)..................    63,368       1,978        65,346
 Average prices:
   Oil (per Bbl)................  $  19.96     $ 19.81      $  19.96
   NGLs (per Bbl)...............  $     --     $    --      $     --
   Gas (per Mcf)................  $   2.27     $  1.95      $   2.27
   Revenue (per BOE)............  $  16.61     $ 16.21      $  16.60
 Average costs:
   Production costs (per BOE):
     Lease operating expense....  $   3.39     $  4.75      $   3.43
     Production taxes...........       .94          --           .91
     Workovers..................       .28          --           .27
                                  --------     -------      --------
       Total....................  $   4.61     $  4.75      $   4.61
   Depletion expense (per BOE)..  $   4.25     $  5.73      $   4.30
</TABLE>
 
- ---------------
 
(a)  These amounts are calculated without making pro forma adjustments for any
     acquisitions, divestitures or drilling activity that occurred during the
     respective years.
 
(b)  Represents production associated with the Company's Australian subsidiaries
     prior to their divestiture in 1996.
 
                                       19
<PAGE>   20
 
     PRODUCTIVE WELLS. The following table sets forth the number of productive
oil and gas wells attributable to the Company's properties as of December 31,
1998, 1997 and 1996.
 
                              PRODUCTIVE WELLS(A)
 
<TABLE>
<CAPTION>
                                                 GROSS PRODUCTIVE WELLS   NET PRODUCTIVE WELLS
                                                 ----------------------   ---------------------
                                                  OIL     GAS    TOTAL     OIL     GAS    TOTAL
                                                 -----   -----   ------   -----   -----   -----
<S>                                              <C>     <C>     <C>      <C>     <C>     <C>
Year ended December 31, 1998:
  United States................................  6,280   4,130   10,410   3,578   2,443   6,021
  Argentina....................................    443     158      601     298     103     401
  Canada.......................................  1,719     454    2,173     715     241     956
                                                 -----   -----   ------   -----   -----   -----
  Total........................................  8,442   4,742   13,184   4,591   2,787   7,378
                                                 =====   =====   ======   =====   =====   =====
Year ended December 31, 1997:
  United States................................  6,075   3,931   10,006   3,399   2,326   5,725
  Argentina....................................    342     122      464     228      84     312
  Canada.......................................  1,666     428    2,094     667     202     869
                                                 -----   -----   ------   -----   -----   -----
  Total........................................  8,083   4,481   12,564   4,294   2,612   6,906
                                                 =====   =====   ======   =====   =====   =====
Year ended December 31, 1996:
  United States................................  5,572   1,393    6,965   3,119     650   3,769
  Argentina....................................      5      --        5       1      --       1
                                                 -----   -----   ------   -----   -----   -----
  Total........................................  5,577   1,393    6,970   3,120     650   3,770
                                                 =====   =====   ======   =====   =====   =====
</TABLE>
 
- ---------------
 
(a)  Productive wells consist of producing wells and wells capable of
     production, including shut-in wells. One or more completions in the same
     well bore are counted as one well. Any well in which one of the multiple
     completions is an oil completion is classified as an oil well. As of
     December 31, 1998, the Company owned interests in 181 wells containing
     multiple completions.
 
     LEASEHOLD ACREAGE. The following table sets forth information about the
Company's developed, undeveloped and royalty leasehold acreage as of December
31, 1998.
 
                               LEASEHOLD ACREAGE
 
<TABLE>
<CAPTION>
                                          DEVELOPED ACREAGE        UNDEVELOPED ACREAGE
                                       -----------------------   ------------------------   ROYALTY
                                       GROSS ACRES   NET ACRES   GROSS ACRES   NET ACRES    ACREAGE
                                       -----------   ---------   -----------   ----------   -------
<S>                                    <C>           <C>         <C>           <C>          <C>
  United States......................   1,505,137      958,845    1,230,934       705,543   422,246
  Canada.............................     332,000      151,000      620,000       397,000        --
  Argentina..........................     655,000      256,000    1,152,000       737,000        --
  South Africa and Gabon.............          --           --   13,813,937    13,513,937        --
                                        ---------    ---------   ----------    ----------   -------
  Total..............................   2,492,137    1,365,845   16,816,871    15,353,480   422,246
                                        =========    =========   ==========    ==========   =======
</TABLE>
 
                                       20
<PAGE>   21
 
     DRILLING ACTIVITIES. The following table sets forth the number of gross and
net productive and dry wells in which the Company had an interest that were
drilled and completed during the years ended December 31, 1998, 1997 and 1996.
This information should not be considered indicative of future performance, nor
should it be assumed that there is necessarily any correlation between the
number of productive wells drilled and the oil and gas reserves generated
thereby or the costs to the Company of productive wells compared to the costs of
dry wells.
 
                              DRILLING ACTIVITIES
 
<TABLE>
<CAPTION>
                                                       GROSS WELLS                 NET WELLS
                                                 ------------------------   ------------------------
                                                 YEAR ENDED DECEMBER 31,    YEAR ENDED DECEMBER 31,
                                                 ------------------------   ------------------------
                                                 1998    1997    1996(b)    1998     1997    1996(b)
                                                 -----   -----   --------   -----   ------   -------
<S>                                              <C>     <C>     <C>        <C>     <C>      <C>
United States:
  Productive wells:
     Development...............................   385     483      535      285.9    341.2    362.9
     Exploratory...............................    18      38       37       13.4     23.8     24.2
  Dry holes:
     Development...............................    13      18        7        8.8      8.8      4.4
     Exploratory...............................     5      46       10        3.0     30.3      6.0
                                                  ---     ---      ---      -----   ------    -----
                                                  421     585      589      311.1    404.1    397.5
                                                  ---     ---      ---      -----   ------    -----
Argentina:
  Productive wells:
     Development...............................    41       4        3       39.1       .6       .4
     Exploratory...............................    11       1       --       10.6       .1       --
  Dry holes:
     Development...............................     5      --       --        5.0       --       --
     Exploratory...............................    11       1        3        9.7       .1       .4
                                                  ---     ---      ---      -----   ------    -----
                                                   68       6        6       64.4       .8       .8
                                                  ---     ---      ---      -----   ------    -----
Canada:
  Productive wells:
     Development...............................    54      --       --       37.1       --       --
     Exploratory...............................    10      --       --        7.2       --       --
  Dry holes:
     Development...............................     6      --       --        5.4       --       --
     Exploratory...............................     4      --       --        3.0       --       --
                                                  ---     ---      ---      -----   ------    -----
                                                   74      --       --       52.7       --       --
                                                  ---     ---      ---      -----   ------    -----
Other foreign:
  Productive wells:
     Development...............................    --      --        2         --       --       .3
     Exploratory...............................     2      --       --         .7       --       --
  Dry holes:
     Development...............................    --      --        1         --       --       .2
     Exploratory...............................     3       1        1        1.7       .4       .2
                                                  ---     ---      ---      -----   ------    -----
                                                    5       1        4        2.4       .4       .7
                                                  ---     ---      ---      -----   ------    -----
          Total................................   568     592      599      430.6    405.3    399.0
                                                  ===     ===      ===      =====   ======    =====
Success ratio(a)...............................    92%     89%      96%        92%      90%      97%
</TABLE>
 
- ---------------
 
(a)  Represents those wells that were successfully completed as productive
     wells.
 
(b)  The 1996 Australian amounts include only three months of activity related
     to the Company's Australian properties prior to their sale in March 1996.
 
                                       21
<PAGE>   22
 
     The following table sets forth information about the Company's wells that
were in progress at December 31, 1998.
 
<TABLE>
<CAPTION>
                                                              GROSS WELLS   NET WELLS
                                                              -----------   ---------
<S>                                                           <C>           <C>
United States:
  Development...............................................      58          43.7
  Exploratory...............................................       8           3.8
                                                                  --          ----
                                                                  66          47.5
                                                                  --          ----
Argentina:
  Development...............................................       3           3.0
  Exploratory...............................................       4           3.4
                                                                  --          ----
                                                                   7           6.4
                                                                  --          ----
Canada:
  Development...............................................       2           1.7
  Exploratory...............................................       1            .3
                                                                  --          ----
                                                                   3           2.0
                                                                  --          ----
          Total.............................................      76          55.9
                                                                  ==          ====
</TABLE>
 
ITEM 3. LEGAL PROCEEDINGS
 
     The Company is party to various legal proceedings, which are described
under "Legal actions" in Note H of Notes to Consolidated Financial Statements
included in "Item 8. Financial Statements and Supplementary Data". The Company
is also party to other litigation incidental to its business. The claims for
damages from such other legal actions are not in excess of 10 percent of the
Company's current assets and the Company believes none of these actions to be
material.
 
                                    PART II
 
ITEM 5. MARKET FOR REGISTRANT'S COMMON STOCK AND RELATED STOCKHOLDER MATTERS
 
     The Company's Common Stock is listed and traded on the New York Stock
Exchange and the Toronto Stock Exchange under the symbol "PXD". The following
table sets forth, for the periods indicated, the high and low sales prices for
the Company's Common Stock, as reported in the New York Stock Exchange composite
transactions, and the amount of dividends paid.
 
<TABLE>
<CAPTION>
                                                                                 DIVIDENDS
                                                              HIGH     LOW     PAID PER SHARE
                                                              -----    ----    --------------
<S>                                                           <C>      <C>     <C>
1998
  Fourth quarter............................................  $16      $ 7 3/4        --
  Third quarter.............................................  $24 11/16 $13 1/4      $.05
  Second quarter............................................  $25 15/16 $21 3/8        --
  First quarter.............................................  $30      $20 5/8      $.05
1997
  Fourth quarter............................................  $43 13/16 $25 5/8        --
  Third quarter.............................................  $44 3/8  $34 3/4      $.05
  Second quarter............................................  $36 3/16 $28 1/2        --
  First quarter.............................................  $37 5/8  $28 7/8      $.05
</TABLE>
 
     On February 26, 1999, the last reported sales price of the Company's Common
Stock, as reported in the New York Stock Exchange composite transactions, was
$5 3/16 per share.
 
                                       22
<PAGE>   23
 
     As of February 26, 1999, the Company's Common Stock was held by
approximately 35,000 holders of record, representing approximately 80,000 total
owners.
 
     Since the third quarter of 1991, the Company has paid a cash dividend of
$.05 per share of Common Stock in the first and third quarters of each calendar
year; however, due to the current trend of declining commodity prices, the
Company's Board of Directors has elected to discontinue the declaration of cash
dividends in 1999 and future years.
 
ITEM 6. SELECTED FINANCIAL DATA
 
     The following selected consolidated financial data for the Company should
be read in conjunction with "Item 7. Management's Discussion and Analysis of
Financial Condition and Results of Operations" and the Company's Consolidated
Financial Statements, related notes and other financial information included in
"Item 8. Financial Statements and Supplementary Data".
 
<TABLE>
<CAPTION>
                                                           YEAR ENDED DECEMBER 31,
                                            -----------------------------------------------------
                                              1998      1997(a)      1996       1995     1994(b)
                                            --------   ---------   --------   --------   --------
                                                    (IN MILLIONS, EXCEPT PER SHARE DATA)
<S>                                         <C>        <C>         <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Revenues:
     Oil and gas..........................  $  711.5   $   536.8   $  396.9   $  375.7   $  337.6
     Natural gas processing...............        --          --       23.8       33.2       39.2
     Gas marketing........................        --          --         --       76.8      103.0
     Interest and other...................      10.4         4.3       17.5       11.4        6.9
     Gain (loss) on disposition of assets,
       net(c).............................       (.4)        4.9       97.1       16.6        9.5
                                            --------   ---------   --------   --------   --------
                                               721.5       546.0      535.3      513.7      496.2
                                            --------   ---------   --------   --------   --------
  Costs and expenses:
     Oil and gas production...............     223.5       144.2      110.3      130.9      127.1
     Natural gas processing...............        --          --       12.5       25.9       33.6
     Gas marketing........................        --          --         --       75.7      101.5
     Depletion, depreciation and
       amortization.......................     337.3       212.4      112.1      159.1      145.4
     Impairment of oil and gas properties
       and natural gas processing
       facilities.........................     459.5     1,356.4         --      130.5         --
     Exploration and abandonments.........     121.9        77.2       23.0       27.5       25.2
     General and administrative...........      73.0        48.8       28.4       37.4       29.0
     Reorganization.......................      33.2          --         --         --         --
     Interest.............................     164.3        77.5       46.2       65.4       50.6
     Other................................      39.6         7.1        2.5       11.3        4.3
                                            --------   ---------   --------   --------   --------
                                             1,452.3     1,923.6      335.0      663.7      516.7
                                            --------   ---------   --------   --------   --------
  Income (loss) before income taxes and
     extraordinary item...................    (730.8)   (1,377.6)     200.3     (150.0)     (20.5)
  Income tax benefit (provision)..........     (15.6)      500.3      (60.1)      45.9        6.5
                                            --------   ---------   --------   --------   --------
  Income (loss) before extraordinary
     item.................................    (746.4)     (877.3)     140.2     (104.1)     (14.0)
  Extraordinary item......................        --       (13.4)        --        4.3        (.6)
                                            --------   ---------   --------   --------   --------
Net income (loss).........................  $ (746.4)  $  (890.7)  $  140.2   $  (99.8)  $  (14.6)
                                            ========   =========   ========   ========   ========
  Income (loss) before extraordinary item
     per share:
     Basic................................  $  (7.46)  $  (16.88)  $   3.95   $  (2.96)  $   (.47)
                                            ========   =========   ========   ========   ========
     Diluted..............................  $  (7.46)  $  (16.88)  $   3.47   $  (2.96)  $   (.47)
                                            ========   =========   ========   ========   ========
</TABLE>
 
                                       23
<PAGE>   24
 
<TABLE>
<CAPTION>
                                                           YEAR ENDED DECEMBER 31,
                                            -----------------------------------------------------
                                              1998      1997(A)      1996       1995     1994(B)
                                            --------   ---------   --------   --------   --------
                                                    (IN MILLIONS, EXCEPT PER SHARE DATA)
<S>                                         <C>        <C>         <C>        <C>        <C>
  Net Income (loss) per share:
     Basic................................  $  (7.46)  $  (17.14)  $   3.95   $  (2.84)  $   (.49)
                                            ========   =========   ========   ========   ========
     Diluted..............................  $  (7.46)  $  (17.14)  $   3.47   $  (2.84)  $   (.49)
                                            ========   =========   ========   ========   ========
  Dividends per share.....................  $    .10   $     .10   $    .10   $    .10   $    .10
                                            ========   =========   ========   ========   ========
  Weighted average shares outstanding.....     100.1        52.0       35.5       35.1       29.9
OTHER FINANCIAL DATA:
  Cash flows from operating activities....  $  314.1   $   228.2   $  230.1   $  156.6   $  129.8
  Cash flows from investing activities....  $ (517.0)  $  (341.2)  $   13.7   $  (52.6)  $ (446.0)
  Cash flows from financing activities....  $  190.9   $   166.0   $ (245.4)  $ (107.9)  $  331.4
BALANCE SHEET DATA:
  Working capital (deficit)(d)............  $ (324.8)  $    46.6   $   26.1   $   31.5   $   43.7
  Property, plant and equipment, net......  $3,034.1   $ 3,515.8   $1,040.4   $1,121.7   $1,349.9
  Total assets............................  $3,481.3   $ 4,153.0   $1,199.9   $1,319.2   $1,604.9
  Long-term obligations...................  $2,101.2   $ 2,124.0   $  329.0   $  603.2   $  727.2
  Preferred stock of subsidiary...........  $     --   $      --   $  188.8   $  188.8   $  188.8
  Total stockholders' equity..............  $  789.1   $ 1,548.8   $  530.3   $  411.0   $  509.6
</TABLE>
 
- ---------------
 
(a)  Includes amounts relating to the acquisition of Mesa beginning in August
     1997 and the acquisition of Chauvco as of December 18, 1997.
 
(b)  Includes amounts relating to the acquisition of Bridge Oil Limited in July
     1994 and the acquisition of properties from PG&E Resources Company in
     August 1994.
 
(c)  Includes a gain of $83.3 million in 1996 related to the disposition of
     certain wholly-owned subsidiaries.
 
(d)  The 1998 working capital deficit includes $306.5 million of current
     maturities of long-term debt, including required reductions in borrowings
     under the Company's credit facilities and other current debt obligations.
     See "1999 Outlook -- Credit facilities" included in "Item 7. Management's
     Discussion and Analysis of Financial Condition and Results of Operations"
     and Note E of Notes to Consolidated Financial Statements included in "Item
     8. Financial Statements and Supplementary Data".
 
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS
 
FORMATION OF PIONEER
 
     Pioneer Natural Resources Company ("Pioneer", or the "Company"), a Delaware
corporation, was formed by the merger of Parker & Parsley Petroleum Company
("Parker & Parsley") and MESA Inc. ("Mesa") on August 7, 1997. On December 18,
1997, the Company was significantly expanded by the acquisition of the Canadian
and Argentine oil and gas business of Chauvco Resources Ltd. ("Chauvco"), a
publicly traded, independent oil and gas company based in Calgary, Canada.
Pioneer is an oil and gas exploration and production company with ownership
interests in oil and gas properties located in the United States, Argentina,
Canada and South Africa.
 
     The combined physical assets and management resources of Parker & Parsley,
Mesa and Chauvco have created a company with a solid foundation of complementary
assets and industry expertise. This foundation is anchored by the Hugoton gas
field located in Southwest Kansas, the West Panhandle gas field located in the
Texas Panhandle, and the Spraberry oil and gas field in West Texas. Each of
these fields provides consistent and dependable production, cash flow and
ongoing development opportunities. These three areas are complemented by the
exploration and development opportunities and oil and gas production contributed
by Pioneer's assets in the United States Gulf Coast area, Argentina and Canada.
These assets create a portfolio of resources and opportunities that are well
balanced between oil, natural gas liquids and gas; and, that are balanced
between long-lived, dependable production and exploration and development
opportunities. Along
                                       24
<PAGE>   25
 
with these assets, the Company has a team of dedicated employees that represent
the professional disciplines and sciences that will allow Pioneer to maximize
the long-term profitability and net asset values inherent in its physical
assets.
 
     In accordance with the provisions of Accounting Principles Board Opinion
No. 16, "Business Combinations", both the merger with Mesa and the acquisition
of Chauvco have been accounted for as purchases by the Company (formerly Parker
& Parsley). As a result, the historical financial statements of the Company are
those of Parker & Parsley prior to August 1997, and present the addition of
Mesa's and Chauvco's assets and liabilities as acquisitions by the Company in
August and December 1997, respectively.
 
FINANCIAL PERFORMANCE
 
     The Company reported a net loss of $746.4 million ($7.46 per share) for the
year ended December 31, 1998 as compared to a net loss of $890.7 million ($17.14
per share) and net income of $140.2 million ($3.95 per share) for the years
ended December 31, 1997 and 1996, respectively. The 1998 results were
significantly impacted by declining commodity prices, a full year of production
volumes from the assets acquired from Mesa and Chauvco, provisions for the
impairment of proved and unproved oil and gas properties, increased interest and
general and administrative expenses, reorganization initiatives and a valuation
allowance recognized to reduce the carrying value of the Company's deferred tax
assets.
 
     Crude oil and natural gas prices have declined substantially since 1996.
The average prices realized by the Company in 1998, including the effects of oil
and gas hedges, were $13.08 per Bbl of oil, $8.90 per Bbl of NGL and $1.82 per
Mcf of gas; as compared to average realized prices for oil, NGLs and gas of
$18.51 per Bbl, $12.59 per Bbl and $2.20 per Mcf, respectively, in 1997; and,
average realized prices for oil and gas of $19.96 per Bbl and $2.27 per Mcf,
respectively, in 1996. The effects of the declining prices on the Company's
results of operations and net cash generated by operating activities have been
mitigated by strategic oil and gas price hedges and increased production
volumes. Primarily as a result of the additions of the Mesa and Chauvco oil and
gas properties, 1998 oil, NGL and gas production increased to 62,875 MBOE as
compared to total production of 35,363 MBOE and 23,916 MBOE in 1997 and 1996,
respectively. Oil and gas production costs and depletion, depreciation and
amortization expense increased to $223.5 million and $337.3 million,
respectively, in 1998, primarily as a result of increased production volumes.
Oil and gas production costs and depletion, depreciation and amortization
expense were $144.2 million and $212.4 million, respectively, in 1997 and $110.3
and $112.1 million, respectively, in 1996.
 
     The declining commodity price outlooks and performance issues prompted the
Company to review its oil and gas properties for impairment in 1998 and 1997,
resulting in non-cash, pre-tax impairment provisions of $459.5 million and $1.4
billion in 1998 and 1997, respectively. Exploration and abandonments expense for
1998 was $121.9 million as compared to $77.2 million and $23.0 million in 1997
and 1996, respectively, reflecting continued expansion of the Company's
exploration program into 1998. Interest and general and administrative expenses
were $164.3 million and $73.0 million in 1998, respectively, as compared to
respective expenses of $77.5 million and $48.8 million in 1997 and $46.2 million
and $28.4 million in 1996. The increase in interest expense is primarily
reflective of a full year of interest expense incurred on the debt that was
assumed in the Mesa and Chauvco acquisitions and increases in debt during 1998
to fund a portion of the Company's 1998 capital expenditures. The increase in
general and administrative expenses similarly reflects a full year of corporate
overhead and other costs incurred to manage a larger corporate entity.
 
     During 1998, the Company implemented cost containment initiatives intended
to increase future operational and administrative efficiencies. Those
initiatives included the closings of the Company's regional offices in Oklahoma
City, Oklahoma, Corpus Christi, Texas, and Houston, Texas, the elimination of
approximately 350 employee positions and other initiatives. The $33.2 million
reorganization charge recognized during 1998 is a result of these initiatives.
Other expenses increased to $39.6 million in 1998, as compared to $7.1 million
and $2.5 million in 1997 and 1996, respectively. Other expense for 1998
included, and increased primarily as a result of, $20.5 million of
mark-to-market adjustments of non-hedge foreign currency and Btu swap agreements
previously owned by Chauvco and Mesa; a $9.6 million write-off of deferred
compensation arising from change of control features in the Company's incentive
plans; $4.4 million
 
                                       25
<PAGE>   26
 
of other expenses associated with the Company's operations in Argentina and
Canada; and, $3.3 million of bad debt expense.
 
     The net loss for 1998 was also impacted by a $271.1 million valuation
allowance recognized to reduce the carrying value of the Company's deferred tax
assets. This charge, which significantly impacted the Company's 1998 net loss,
is a non-cash component of operating results and did not impact the Company's
net cash provided by operating activities. Net cash provided by operating
activities was $314.1 million for the year ended December 31, 1998, as compared
to $228.2 million for the year ended December 31, 1997 and to $230.1 million for
the year ended December 31, 1996. The additional cash flow generated by the
increased production realized from the acquired Mesa and Chauvco properties was
partially offset by the aforementioned declining commodity prices and increased
costs and expenses.
 
     Total debt has increased to $2.2 billion at December 31, 1998 from $1.9
billion at December 31, 1997, due principally to capital expenditures in 1998
exceeding cash flow provided by operating activities. The Company strives to
maintain its outstanding indebtedness at a moderate level in order to provide
sufficient financial flexibility for future opportunities. The Company's total
book capitalization at December 31, 1998 was $3.0 billion, consisting of total
debt of $2.2 billion and stockholders' equity of $.8 billion. As a result of
increases in debt and reductions in shareholders' equity primarily resulting
from 1998 and 1997 non-cash impairment provisions (see Note M and Note O of
Notes to Consolidated Financial Statements included in "Item 8. Financial
Statements and Supplementary Data"), the Company's debt to total capitalization
increased to 73 percent at December 31, 1998 from 56 percent at December 31,
1997.
 
     See "Results of Operations", below, for more in-depth discussions of the
Company's oil and gas producing activities, including discussions pertaining to
oil and gas production volumes, prices, hedging activities, costs and expenses,
capital commitments, capital resources and liquidity.
 
1999 OUTLOOK
 
     The Company's results of operations and financial condition in 1999 are
expected to be significantly affected by industry-wide conditions and Company
specific attributes and plans. The declining trend in commodity prices has
resulted from a combination of factors which have contributed to increased oil
and gas supplies and decreased demand for those commodities. The most
significant of those factors include increased crude oil exports by Iraq and
other members of the Organization of Petroleum Exporting Countries ("OPEC"),
mild weather patterns in heavy energy consuming areas during 1998 and 1997, and
declining demand for energy in the Asian and other formerly-high-growth areas of
the world due to regional recessions. During 1999, the Company anticipates a
continuation of the unfavorable commodity price environment presently impacting
the oil and gas industry. In response thereto, Pioneer plans to take deliberate
actions to reduce its outstanding indebtedness and to protect its operating cash
flows. The specific initiatives being taken include reductions in capital
expenditures, the divestment of non-strategic assets, the continuation of cost
containment measures and the maintenance of hedge positions designed to reduce
the volatility of 1999 realized natural gas prices.
 
     Capital expenditures. During 1999, the Company plans to reduce capital
expended for oil and gas property additions to approximately $100 million, of
which $25 million has been budgeted for exploration expenditures and $75 million
has been budgeted for exploitation projects. Geographically, during 1999 the
Company expects capital expenditures of $60 million in the United States, $25
million in Argentina and $15 million in Canada. Pioneer's long-lived reserves
and dependable production in the Hugoton and West Panhandle gas fields and
Spraberry oil field allow it the flexibility necessary to make significant
changes in its capital allocation plans without significantly impacting near
term production volumes. During 1999, Pioneer's exploration and exploitation
programs will focus on natural gas projects. The Company's 1999 exploitation
program will focus on gas development in the Gulf Coast area and West Panhandle
field in the United States, the Chinchaga field in Canada, and in the Neuquen
Basin in Argentina. Exploration drilling will be concentrated in the Gulf of
Mexico and the onshore Gulf Coast area. The Company will participate in one or
two wells in the Gulf of Mexico deep-water Mississippi Canyon Block 305. The
first well was spudded in January and is scheduled for preliminary evaluations
in March. Two additional wells are planned for 1999
 
                                       26
<PAGE>   27
 
onshore in the Gulf Coast area or in East Texas where several shallower
exploration prospects have been defined from Pioneer's 3-D database. The
Company's exploration programs in South Africa, Gabon, and the Gulf Coast
transition zone are targeted for comprehensive studies that will focus on
analysis, ranking and timing of prospects during 1999. Seismic studies are
currently planned to commence in Gabon during late 1999 or early 2000. No new
wells are planned during 1999 in South Africa, where the Company is evaluating
farmout and other risk sharing opportunities. In comparison, during 1999, the
Company intends to use the excess of cash provided by operating activities over
capital expenditures for oil and gas producing activities to reduce outstanding
indebtedness.
 
     Asset divestitures. The Company has announced its intentions to sell
non-strategic oil and gas assets for gross proceeds of $500 million to $600
million in 1999 and 2000. As is discussed more fully below in "Trends and
Uncertainties -- Asset Dispositions", the Company has entered into a purchase
and sale agreement (the "Agreement") to sell certain non-strategic oil and gas
properties. The proceeds to be realized from the disposition, if the Agreement
is consummated, are $335 million, of which $41 million represents an irrevocable
option fee that has been paid to the Company as of December 31, 1998. If
consummated, the Agreement requires a final payment to Pioneer of $294 million
of proceeds on or before March 31, 1999. If the Agreement is not consummated,
the $41 million of irrevocable option fees would be recognized as 1999 earnings.
The Company is continuing to review its portfolio of oil and gas properties to
identify other non-strategic properties for divestiture. The realization of the
Company's plans to divest of the other non-strategic oil and gas properties in
1999 or in 2000 is contingent upon, among other things, the Company's ability to
find one or more purchasers willing to purchase the non-strategic assets at
prices acceptable to the Company and the purchasers' ability to complete the
transaction. There can be no assurances that the Company will be successful in
completing the divestitures in 1999 or in 2000. The Company intends to use
divestiture proceeds, if such proceeds are realized, to reduce outstanding
indebtedness during 1999 and 2000.
 
     Cost containment. In 1998, the Company initiated a number of cost
containment measures. Such measures included centralizing its domestic
operations which resulted in the closing of its regional offices in Oklahoma
City, Oklahoma, Corpus Christi, Texas and Houston, Texas; the termination of 350
employees, including several officer positions; and the reduction of 1999
salaries among senior officers. These initiatives were designed to increase
operational and administrative efficiencies, thereby reducing future production
costs and general and administrative costs per BOE. Associated with these
initiatives, the Company anticipates that additional reorganization charges of
approximately $5 million will be recognized during the first quarter of 1999.
See Note N of Notes to Consolidated Financial Statement included in "Item 8.
Financial Statements and Supplementary Data" for specific discussion and
disclosures regarding the Company's reorganization provisions.
 
     Hedging activities. The declines in commodity prices have had, and continue
to have, a significant impact on the Company's financial condition and results
of operations. To mitigate the impact of changing prices on the Company's
financial condition and results of operations, Pioneer, from time to time,
enters into commodity derivative contracts as hedges against oil and gas price
risk. As of December 31, 1998, the Company had entered into 1999 hedge contracts
for a combined notional volume of 284.7 MMcf of natural gas per day at a
weighted average floor price of $2.14 per MMBtu (the Company has sold 1999 put
options for a notional volume of 114.3 MMcf per day at an average index price of
$1.82 per MMBtu, thereby releasing the average hedge floor on 114.3 MMcf per day
of gas to the lesser of $2.12 per MMBtu or the index price plus $.30 per MMBtu).
See Notes B, C and J of Notes to Consolidated Financial Statements included in
"Item 8. Financial Statements and Supplementary Data".
 
     Income taxes. The Company's ability to realize its deferred tax assets is
dependent upon generating sufficient taxable income prior to their expiration.
The Company believes that there is a risk, in light of the current economic
conditions in the oil and gas industry, that certain of its net operating loss
carryforwards and other credit carryforwards may expire unused. In accordance
with generally accepted accounting principles, the Company must reduce the
carrying value of its deferred tax assets if it cannot be determined that it is
more likely than not that it will be able to realize the deferred tax assets in
future operating periods. Accordingly, the Company has established a valuation
allowance of $271.1 million in 1998 to reduce the carrying value of the assets.
Although realization is not assured for the remaining deferred tax assets, the
                                       27
<PAGE>   28
 
Company believes it is more likely than not that they will be realized through
future taxable earnings or alternative tax planning strategies. However, the net
deferred tax assets could be reduced further if the Company's estimate of
taxable income in future periods is significantly reduced or alternative tax
planning strategies are no longer viable. As a result of this situation, it is
likely that the Company's effective tax rate in 1999 will be minimal or nil if
the Company recognizes a loss before income taxes. If the Company recognizes
income before income taxes in 1999, its effective tax rate will be reduced to
the extent that taxable earnings are recognized in those tax jurisdictions
relative to which the Company established its 1998 valuation allowances.
 
     Credit facilities. As of December 31, 1998, the Company was a borrower
under three separate credit facilities (the "Credit Facilities") that provided
for combined loan commitments of $1.4 billion, comprised of a $1.075 billion
primary credit facility (the "Primary Facility") that matures on August 7, 2002;
a $290 million Canadian Credit Facility, (the "Canadian Facility"), which
converted in the fourth quarter of 1998 to a $276 million term loan that matures
on December 19, 2003; and an $85 million credit facility (the "364-day
Facility") that matures on August 5, 1999. On December 31, 1998, the Company had
$993.6 million of outstanding borrowings under the Primary Facility, $276.0
million of outstanding borrowings under the Canadian Facility and no borrowings
under the 364-day Facility. As of December 31, 1998, advances on the Credit
Facilities bear interest at the option of the Company, based on (a) the prime
rate of NationsBank of Texas, N.A. ("Prime Rate") (7.75 percent at December 31,
1998), (b) a Eurodollar rate (substantially equal to the London Interbank
Offered Rate ("LIBOR")) adjusted for the reserve requirement as determined by
the Board of Governors of the Federal Reserve System with respect to
transactions in Eurocurrency liabilities ("LIBOR Rate"), or (c) a competitive
bid rate as quoted by the lending banks electing to participate pursuant to a
request by the Borrower. The interest rates on the LIBOR Rate advances vary,
with the interest rate margin ranging from 18 basis points to 55 basis points,
including commitment utilization fees.
 
     On March 19, 1999, the Company and the syndicate of banks participating in
the Credit Facilities executed amendments to the Credit Facilities that provide
for a $495 million reduction in the combined loan commitments under the Credit
Facilities by December 31, 1999; an increase in the maximum interest rate margin
on LIBOR Rate advances to 350 basis points, including facility and leverage
fees; provisions, under certain circumstances, for enhancing the participating
banks' collateral rights; and, amendment of certain associated debt covenants,
the most restrictive covenant requires the maintenance of a ratio of outstanding
Company senior debt to earnings before interest, depletion, depreciation,
amortization, income taxes, exploration and abandonment and other non-cash
expenses ("EBITDAX") not to exceed 5.75 to one through September 30, 1999, 4.25
to one through March 31, 2000, and 3.5 to one thereafter. Additionally, the
amendment provisions provide for the consolidation of the Primary Facility and
the Canadian Facility. The 1999 amendments to the Credit Facilities will
decrease the Company's liquidity and are expected to increase the Company's
weighted average rate of interest on outstanding indebtedness. To satisfy the
commitment reduction provisions of the amended Credit Facilities, the Company
intends to reduce its outstanding borrowings through the use of funds generated
by the individual or combined sources of operating activities, oil and gas
property divestitures, borrowings under subordinated debt agreements or
additional issuances of equity. The ultimate impact of the amendments on the
Company's results of operations and financial condition as of and for the year
ending December 31, 1999 is uncertain and will depend on the amount of debt
reduction that the Company is able to achieve in 1999. See "Results of
Operations -- Capital Commitments, Capital Resources and Liquidity", below, and
Note E to Notes to Consolidated Financial Statements in "Item 8. Financial
Statements and Supplementary Data" for further discussions relative to the
Company's Credit Facilities and outstanding borrowings.
 
TRENDS AND UNCERTAINTIES
 
COMMODITY PRICES
 
     The realized oil and gas prices that Pioneer reports are based on the
market price received for the commodity adjusted by the results of the Company's
hedging activities. Historically, worldwide oil and gas prices have been
volatile and subject to significant changes in response to real and perceived
conditions in world politics, weather patterns and other fundamental supply and
demand variables.
 
                                       28
<PAGE>   29
 
     Since 1996, there has been a declining trend in world oil prices and, more
recently but to a lesser extent, natural gas prices. The benchmark daily average
NYMEX West Texas Intermediate crude oil closing price for the year ended
December 31, 1998 has declined 30 percent and 35 percent, respectively, as
compared with the same averages for 1997 and 1996; and, the benchmark daily
average NYMEX Henry Hub closing natural gas price for the year ended December
31, 1998 has declined 14 percent and 15 percent, respectively, as compared with
the same averages for 1997 and 1996.
 
ASSET DISPOSITIONS
 
     As is discussed in "1999 Outlook", above, the Company has announced its
intentions to sell non-strategic oil and gas assets for gross proceeds of $500
million to $600 million in 1999 and 2000. In February 1998, the Company
announced its intentions to sell domestic non-strategic properties and
subsequently signed a purchase and sale agreement (the "Agreement") to sell
certain oil and gas properties representing approximately 10 percent of the
Company's proved reserves. In December 1998, Pioneer announced the re-
negotiation of the Agreement and the sale of an exclusive and irrevocable option
to the buyer to purchase the same properties on or before March 31, 1999. The
proceeds associated with the re-negotiated terms total $335 million, of which
$41 million represents an irrevocable option fee that has been paid to the
Company as of December 31, 1998. The Company's realization of the remaining $294
million of proceeds, which would be used to reduce outstanding indebtedness, is
primarily dependent upon the buyer's ability to finance the purchase and certain
other contingencies defined in the Agreement. As a result, there can be no
assurance that the divestiture of any or all of the properties will be completed
or that the remaining proceeds will be realized. The Company is continuing to
review its portfolio of oil and gas properties to identify other non-strategic
properties for divestiture. The realization of the Company's plans to divest of
the other non-strategic oil and gas properties in 1999 or in 2000 is contingent
upon, among other things, the Company's ability to find one or more purchasers
willing to purchase the non-strategic assets at prices acceptable to the Company
and the purchasers' ability to complete the transaction. There can be no
assurances that the Company will be successful in completing the divestitures in
1999 or in 2000.
 
ASSET IMPAIRMENTS AND VALUATION ALLOWANCES
 
     Neither the longevity nor the extent of the current trend of declining
commodity prices can be assessed with any degree of certainty. A continuation of
the trend, or other relevant factors, could result in further impairment
provisions to the carrying value of the Company's proved and unproved properties
or additional valuation allowances to the Company's deferred tax assets in the
future, which could have a material adverse effect on the Company's financial
condition and results of operations. See Notes B, M and O of Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data" for additional information and disclosures regarding the
Company's accounting policies and attributes pertaining to asset impairments and
income tax valuation allowances.
 
FOREIGN CURRENCIES
 
     The Company has oil and gas business dealings in Canada, Argentina, South
Africa and Gabon. Historically, crude oil sales contracts have been United
States dollar denominated, which significantly reduces foreign currency risks
associated with crude oil operations. Additionally, the Canadian dollar to
United States dollar exchange rate remains relatively stable. The functional
currency of the Company's Argentine operations is the Argentine peso. Presently,
the Argentine peso is valued on a one-to-one relationship with the United States
dollar. The functional currencies of the Company's South African and Gabon
operations are the United States dollar. The Company's operations in South
Africa and Gabon are not presently of a magnitude that would generate
significant foreign currency risk. Although the above described currency
relationships are not expected to change significantly in the near future,
economic and other factors can cause significant and sudden changes in foreign
currency exchange rates that could materially impact the Company's financial
position and future results of operations.
 
                                       29
<PAGE>   30
 
YEAR 2000 PROJECT READINESS
 
     Historically, many computer programs have been developed that use only the
last two digits in a date to refer to a year. As the year 2000 nears, the
inability of such computer programs and embedded technologies to distinguish
between "1900" and "2000" has given rise to the "Year 2000" problem.
Theoretically, such computer programs and related technology could fail outright
or communicate inaccurate data, if not remediated or replaced. With the
proliferation of electronic data interchange, the Year 2000 problem represents a
significant exposure to the entire global community, the full extent of which
cannot be accurately assessed.
 
     In proactive response to the Year 2000 problem, the Company established a
"Year 2000" project to assess, to the extent possible, the Company's internal
Year 2000 problem; to take remedial actions necessary to minimize the Year 2000
risk exposure to the Company and significant third parties with whom it has data
interchange; and, to test its systems and processes once remedial actions have
been taken. The Company has contracted with IBM Global Services to perform the
assessment and remedial phases of its Year 2000 project.
 
     The assessment phase of the Company's Year 2000 project is at varying
stages of completion as it pertains to information technology and
non-information technology applications and systems in the United States, Canada
and Argentina. As of December 31, 1998, the Company estimates that the
assessment phase is approximately 86 percent complete on a worldwide basis and
has included, but is not limited to, the following procedures:
 
     - the identification of necessary remediation, upgrade and/or replacement
       of existing information technology applications and systems;
 
     - the assessment of non-information technology exposures, such as
       telecommunications systems, security systems, elevators and process
       control equipment;
 
     - the initiation of inquiry and dialogue with significant third party
       business partners, customers and suppliers in an effort to understand and
       assess their Year 2000 problems, readiness and potential impact on the
       Company and its Year 2000 problem;
 
     - the implementation of processes designed to reduce the risk of
       reintroduction of Year 2000 problems into the Company's systems and
       business processes; and,
 
     - the formulation of contingency plans for mission-critical information
       technology systems.
 
     The Company expects to complete the assessment phase of its Year 2000
project by the end of the first quarter of 1999 but is being delayed by limited
responses received on inquiries made of third party businesses. To date, the
Company has distributed Year 2000 problem inquiries to over 500 entities and has
received responses to approximately 37 percent of those inquiries.
 
     The remedial phase of the Company's Year 2000 project is also at varying
stages of completion as it pertains to the remediation of information technology
and non-information technology applications and systems in the United States,
Canada and Argentina. As of December 31, 1998, the Company estimates that the
remedial phase is approximately 54 percent complete, on a worldwide basis,
subject to the continuing results of the third party inquiry assessments and the
testing phase. The remedial phase has included the upgrade and/or replacement of
certain application and hardware systems. The Company has upgraded its Artesia
general ledger accounting systems through remedial coding and is currently
testing this system for Year 2000 compliance. The remediation of non-information
technology is expected to be completed during July 1999. The Company's Year 2000
remedial actions have not significantly delayed other information technology
projects or upgrades.
 
     The testing phase of the Company's Year 2000 project is on schedule. The
Company expects to complete the testing of the Artesia system upgrades by March
1999 and all other information technology systems and non-information technology
remediation by the end of the third quarter of 1999.
 
     The Company expects that its total costs related to the Year 2000 problem
will approximate $3.6 million, of which approximately $500 thousand will have
been incurred to replace non-compliant information
 
                                       30
<PAGE>   31
 
technology systems. The Company intends to use its working capital to pay for
the costs of the Year 2000 projects. As of December 31, 1998, the Company's
total costs incurred on the Year 2000 problem were $1.8 million, of which $200
thousand were incurred to replace non-compliant systems.
 
     The risks associated with the Year 2000 problem are significant. A failure
to remedy a critical Year 2000 problem could have a materially adverse affect on
the Company's results of operations and financial condition. The most likely
worst case scenario which may be encountered as a result of a Year 2000 problem
could include information and non-information system failures, the receipt or
transmission of erroneous data, lost data or a combination of similar problems
of a magnitude that cannot be accurately assessed at this time.
 
     In the assessment phase of the Company's Year 2000 project, contingency
plans are being designed to mitigate the exposures to mission critical
information technology systems, such as oil and gas sales receipts; vendor and
royalty cash distributions; debt compliance; accounting; and, employee
compensation. Such contingency plans anticipate the extensive utilization of
third-party data processing services, personal computer applications and the
substitution of courier and mail services in place of electronic data
interchange. Given the uncertainties regarding the scope of the Year 2000
problem and the compliance of significant third parties, there can be no
assurance that contingency plans will have anticipated all Year 2000 scenarios.
 
ACCOUNTING FOR DERIVATIVES
 
     In June 1998, the Financial Accounting Standards Board issued Statement of
Accounting Standards No. 133 "Accounting for Derivative Instruments and Hedging
Activities" ("SFAS 133"). SFAS 133 establishes accounting and reporting
standards for derivative instruments, including certain derivative instruments
embedded in other contracts, (collectively referred to as derivatives) and for
hedging activities. It requires that an entity recognize all derivatives as
either assets or liabilities in the statement of financial position and measure
those instruments at fair value. If certain conditions are met, a derivative may
be specifically designated as (a) a hedge of the exposure to changes in the fair
value of a recognized asset or liability or an unrecognized firm commitment, (b)
a hedge of the exposure to variable cash flows of a forecasted transaction, or
(c) a hedge of the foreign currency exposure of a net investment in a foreign
operation, an unrecognized firm commitment, an available-for-sale security, or a
foreign-currency-denominated forecasted transaction.
 
     SFAS 133 is effective for all fiscal quarters of fiscal years beginning
after June 15, 1999. The Company has not determined what effect, if any, SFAS
133 will have on its consolidated financial statements.
 
                                       31
<PAGE>   32
 
RESULTS OF OPERATIONS
 
  OIL AND GAS PRODUCTION
 
     The following table describes the results of the Company's oil and gas
production activities during 1998, 1997 and 1996.
 
<TABLE>
<CAPTION>
                                                                YEAR ENDED DECEMBER 31,
                                                         -------------------------------------
                                                            1998          1997          1996
                                                         ----------    -----------    --------
                                                          (IN THOUSANDS, EXCEPT AVERAGE PRICE
                                                                    AND COST DATA)
<S>                                                      <C>           <C>            <C>
Revenues:
  Oil and gas..........................................  $  711,492    $   536,782    $396,931
  Gain on disposition of oil and gas properties,
     net(a)............................................          53          3,304       7,786
                                                         ----------    -----------    --------
                                                            711,545        540,086     404,717
                                                         ----------    -----------    --------
Costs and expenses:
  Oil and gas production...............................     223,551        144,170     110,334
  Depletion............................................     322,294        204,450     102,803
  Impairment of oil and gas properties.................     459,519      1,356,390          --
  Exploration and abandonments.........................      51,008         37,603      12,653
  Geological and geophysical...........................      70,850         39,557       9,054
                                                         ----------    -----------    --------
                                                          1,127,222      1,782,170     234,844
                                                         ----------    -----------    --------
  Operating profit (loss) (excluding general and
     administrative expense and income taxes)..........  $ (415,677)   $(1,242,084)   $169,873
                                                         ==========    ===========    ========
</TABLE>
 
- ---------------
 
(a)  The 1997 amount does not include the gain related to the disposition of the
     Company's subsidiary that owned an interest in oil and gas properties in
     Turkey. The 1996 amount does not include the gain related to the
     disposition of the Company's Australasian assets. See Note L of Notes to
     Consolidated Financial Statements included in "Item 8. Financial Statements
     and Supplementary Data".
 
<TABLE>
<CAPTION>
                                                                 YEAR ENDED DECEMBER 31,
                                                           -----------------------------------
                                                             1998           1997        1996
                                                           --------       --------    --------
                                                           (IN THOUSANDS, EXCEPT AVERAGE PRICE
                                                                     AND COST DATA)
<S>                                                        <C>            <C>         <C>
Production:
  Oil (MBbls)............................................    21,554         13,618      11,275
  NGLs (MBbls)...........................................    10,669          4,267          --
  Gas (MMcf).............................................   183,913        104,868      75,851
  Total (MBOE)...........................................    62,875         35,363      23,916
Average daily production:
  Oil (Bbls).............................................    59,052         37,309      30,805
  NGLs (Bbls)............................................    29,231         11,691          --
  Gas (Mcf)..............................................   503,872        287,309     207,244
Average oil price (per Bbl)..............................  $  13.08       $  18.51    $  19.96
Average NGL price (per Bbl)..............................  $   8.90       $  12.59    $     --
Average gas price (per Mcf)..............................  $   1.82       $   2.20    $   2.27
Costs:
  Lease operating expense (per BOE)......................  $   3.04       $   3.02    $   3.43
  Production taxes (per BOE).............................       .40            .81         .91
  Workover costs (per BOE)...............................       .12            .25         .27
                                                           --------       --------    --------
     Total production costs (per BOE)....................  $   3.56       $   4.08    $   4.61
                                                           ========       ========    ========
  Depletion (per BOE)....................................  $   5.13       $   5.78    $   4.30
</TABLE>
 
     OIL AND GAS REVENUES. Revenues from oil and gas operations totaled $711.5
million in 1998, $536.8 million in 1997 and $396.9 million in 1996, representing
a 33 percent increase from 1997 to 1998 and a 35 percent increase from 1996 to
1997. The revenue increase from 1997 to 1998 is reflective of a 78 percent
increase in BOE production, offset by a 29 percent, 29 percent and 17 percent
decline in prices for oil, NGLs and gas, respectively, from 1997 to 1998. The
increase in production during 1998 was primarily attributable to a full
 
                                       32
<PAGE>   33
 
year of production realized from the Mesa and Chauvco properties acquired in
1997. The increase in revenue from 1996 to 1997 is primarily attributable to
increases in oil and gas production, offset by declines in commodity prices. The
majority of the increased production during 1997 was a direct result of the oil
and gas properties acquired from Mesa.
 
     Parker & Parsley historically accounted for processed natural gas
production as wellhead production on a wet gas basis, while Mesa accounted for
processed natural gas production in two components: natural gas liquids and dry
residue gas. The combined entities own three major gas processing facilities,
and the majority of the gas processed by these facilities is owned by the
Company and produced by Company-operated properties. Consequently, the Company
now produces a higher proportion of processed gas relative to total natural gas
production and accounts for any processed natural gas production as natural gas
liquids and dry residue gas.
 
     Production volumes for 1998 increased by 78 percent from 35,363 MBOE to
62,875 MBOE. This increase is primarily reflective of a full year of production
realized from the properties acquired from Mesa and Chauvco, but also was
impacted favorably by the Company's exploration and development projects. The
properties acquired from Mesa and Chauvco contributed 97 percent of the
production growth from 1997 to 1998. Excluding the production associated with
the Mesa and Chauvco properties and other properties sold during 1998 and 1997,
production increased nine percent during 1998, as compared to 1997, on a BOE
basis.
 
     On a BOE basis, production increased by 48 percent for the year ended
December 31, 1997, as compared to the same period in 1996. The additional
production volumes from the Mesa properties contributed 85 percent of production
growth from 1996 to 1997. The remainder of the increase is a direct result of
the successes of the Company's exploration and exploitation efforts. Such
production growth was particularly evident in light of the fact that a portion
of the average daily oil and gas production for 1996 related to properties
included in the 1996 sale of the Company's Australasian subsidiaries and the
1996 sale of certain non-strategic domestic assets. Excluding production
associated with assets sold during 1996 and the Mesa properties acquired in
1997, on a BOE basis, production increased 14 percent for the year ended
December 31, 1997 as compared to the year ended 1996.
 
     The average oil price received for the year ended December 31, 1998
decreased 29 percent (from $18.51 per Bbl in 1997 to $13.08 per Bbl in 1998);
the average NGL price received in 1998 decreased 29 percent (from $12.59 per Bbl
in 1997 to $8.90 per Bbl in 1998); and the average gas price received in 1998
decreased 17 percent (from $2.20 per Mcf in 1997 to $1.82 per Mcf in 1998). The
average oil price received for the year ended December 31, 1997 decreased seven
percent (from $19.96 per Bbl in 1996 to $18.51 per Bbl in 1997), and the average
gas price received decreased three percent (from $2.27 per Mcf in 1996 to $2.20
per Mcf in 1997). During 1997, the Company received an average of $12.59 per Bbl
for NGLs.
 
  Hedging Activities
 
     The oil and gas prices that the Company reports are based on the market
price received for the commodities adjusted by the results of the Company's
hedging activities. The Company utilizes commodity derivative contracts (swaps,
futures and options) in order to (i) reduce the effect of the volatility of
price changes on the commodities the Company produces and sells, (ii) support
the Company's annual capital budgeting and expenditure plans and (iii) lock in
prices to protect the economics related to certain capital projects.
 
     Crude Oil. All material purchase contracts governing the Company's oil
production are tied directly or indirectly to NYMEX prices. The average oil
price per Bbl that the Company reports includes the effects of oil quality,
gathering and transportation costs and the net effect of the oil hedges. The
Company's average realized price for physical oil sales (excluding hedge
results) for the years ended December 31, 1998, 1997 and 1996 was $11.93 per
Bbl, $19.09 per Bbl and $21.33 per Bbl, respectively. During the year ended
December 31, 1998, the Company recorded a $24.8 million net increase to oil
revenues as a result of its oil price hedges. During the fourth quarter of 1998,
the Company terminated its 1999 crude oil hedge positions and recognized a
deferred gain of $14.0 million associated therewith. The deferred hedge gains
will be recognized as oil revenue during the year ended December 31, 1999 in the
amount of $3.5 million per calendar
                                       33
<PAGE>   34
 
quarter. The Company recorded net reductions to oil revenues of $7.9 million and
$15.4 million for the years ended December 31, 1997 and 1996, respectively, as a
result of its oil price hedges.
 
     Natural Gas Liquids. During 1998, the Company did not enter into natural
gas liquids price hedge contracts. During the year ended December 31, 1997, the
Company realized an average natural gas liquids price for physical sales
(excluding hedge results) of $12.61 per Bbl and recorded a net decrease to
natural gas liquids revenue of $77,600 as a result of hedging.
 
     Natural Gas. The Company employs a policy of hedging a portion of its gas
production based on the index price upon which the gas is actually sold in order
to mitigate the basis risk between NYMEX prices and actual index prices. The
average gas price per Mcf that the Company reports includes the effects of Btu
content, gathering and transportation costs, gas processing and shrinkage and
the net effect of the gas hedges. The Company's average realized price for
physical gas sales (excluding hedge results) for the years ended December 31,
1998, 1997 and 1996 was $1.80 per Mcf, $2.41 per Mcf and $2.39 per Mcf,
respectively. For the year ended December 31, 1998, the Company recorded a net
increase to gas revenues of $3.6 million as a result of its gas price hedges.
The Company recorded net reductions to gas revenues of $21.9 million and $9.0
million for the years ended December 31, 1997 and 1996, respectively, as a
result of its gas price hedges.
 
     See Note J of Notes to Consolidated Financial Statements included in "Item
8. Financial Statements and Supplementary Data" for information concerning the
Company's open hedge positions at December 31, 1998 and the related prices to be
realized.
 
     PRODUCTION COSTS. Total production costs per BOE decreased in 1998 and 1997
by approximately 13 percent and 11 percent, respectively (from $4.61 in 1996 to
$4.08 in 1997 to $3.56 in 1998). The primary component of production costs,
lease operating expense, remained constant in 1998 and decreased by 12 percent
in 1997. Workover costs declined by 52 percent in 1998 and seven percent in
1997. These costs represent the majority of the oil and gas property operating
expenses over which the Company has control and the costs on which the Company
has focused its reduction efforts. Production taxes, which are correlated with
volumes and prices, declined 51 percent in 1998 and 11 percent in 1997
reflecting the decline in commodity prices over the past two years. As discussed
more fully in "Natural Gas Processing" below, the Company adopted a new method
of reporting the financial results of its natural gas processing facilities in
1997, and is now presenting these results as oil and gas production activities.
In 1998 and 1997, the operating margin from the Company's gas plants (i.e.,
third party processing revenues less processing costs and expenses) are included
in oil and gas production costs, specifically lease operating expense. The
additional reductions in lease operating expense during the three years ended
December 31, 1998 are primarily due to the Company's concentrated efforts to
evaluate and reduce all operating costs and the sale of certain high operating
cost properties during 1996.
 
     DEPLETION EXPENSE. Depletion expense per BOE decreased 11 percent in 1998
(to $5.13 in 1998 from $5.78 in 1997) and increased 34 percent in 1997 (from
$4.30 in 1996). The decrease in 1998 was primarily due to the 1997 provision for
impairment that reduced the per BOE carrying values of the Company's oil and gas
properties in accordance with SFAS 121 (see "Impairment of Oil and Gas
Properties" below). The increase in depletion expense per BOE in 1997 was
primarily associated with the fair value allocated to Mesa's long-lived, low
production cost natural gas reserves.
 
     IMPAIRMENT OF OIL AND GAS PROPERTIES. In accordance with Statement of
Financial Accounting Standards No. 121, "Accounting for the Impairment of
Long-Lived Assets and for Long-Lived Assets to be Disposed Of" ("SFAS 121"), the
Company reviews its oil and gas properties for impairment whenever events or
circumstances indicate a decline in the recoverability of the carrying value of
the Company's assets may have occurred. Declining commodity prices in 1998 and
1997, the Company's outlook for future commodity prices and 1998 performance
issues relative to certain oil and gas properties, prompted impairment reviews.
As a result of these reviews, the Company recognized non-cash pre-tax charges of
$312.2 million and $1.4 billion in 1998 and 1997, respectively, related to its
proved oil and gas properties.
 
     In accordance with Statement of Financial Accounting Standards No. 19,
"Accounting and Reporting by Oil and Gas Producing Companies" ("SFAS 19"), the
Company periodically assesses its unproved properties
 
                                       34
<PAGE>   35
 
to determine whether they have been impaired. An unproved property may be
impaired if the Company does not intend to drill the prospect as a result of
downward revisions to potential proved reserves, if the results of exploration
or the Company's outlook for future commodity prices indicate that the potential
proved reserves are not sufficient to generate net cash flows to recover the
investment required by the project, or if the Company intends to sell the
property for less than its carrying value. The Company has assessed its unproved
oil and gas properties for impairment and in 1998 recognized a non-cash pre-tax
impairment charge of $147.3 million to reduce the carrying value of its unproved
oil and gas properties.
 
     EXPLORATION AND ABANDONMENTS/GEOLOGICAL AND GEOPHYSICAL COSTS. Exploration
and abandonments/ geological and geophysical costs totaled $121.9 million, $77.2
million and $21.7 million for the years ended December 31, 1998, 1997 and 1996,
respectively. The following table sets forth the components of the Company's
1998, 1997 and 1996 exploration and abandonments/geological and geophysical
costs:
 
<TABLE>
<CAPTION>
                                                                YEAR ENDED DECEMBER 31,
                                                              ----------------------------
                                                                1998      1997      1996
                                                              --------   -------   -------
                                                                     (IN THOUSANDS)
<S>                                                           <C>        <C>       <C>
Exploratory dry holes:
  United States.............................................  $ 15,737   $27,183   $ 6,256
  Argentina.................................................     4,426       252     3,416
  Canada....................................................     1,949        --        --
  Other foreign.............................................     9,486     5,442        15
Geological and geophysical costs:
  United States.............................................    42,755    37,987     7,042
  Argentina.................................................     9,999     1,570       592
  Canada....................................................    14,244        --        --
  Other foreign.............................................     3,851        --     1,420
Leasehold abandonments and other............................    19,411     4,726     2,966
                                                              --------   -------   -------
                                                              $121,858   $77,160   $21,707
                                                              ========   =======   =======
</TABLE>
 
     Approximately 30 percent of the Company's 1998 exploration/exploitation
capital budget was spent on exploratory projects as compared to 28 percent in
1997 and 18 percent in 1996. The increase in 1998 exploratory costs is primarily
due to the initial expenditures made to explore the Argentine and Canadian
properties acquired from Chauvco and the Company's exploration program in South
Africa. The increase in 1997 was primarily the result of increased domestic
exploratory drilling and geological and geophysical activity due to the
expansion of the Company's exploration program. The Company currently
anticipates that its 1999 exploration efforts, although curtailed to reduce
debt, will be concentrated domestically in the Gulf of Mexico and onshore Gulf
Coast region. The Company will participate in one or two wells in the Gulf of
Mexico deep-water Mississippi Canyon Block 305 and two wells in either the
onshore Gulf Coast area or in East Texas where several shallower exploration
prospects have been defined from Pioneer's 3-D database. The Company's
exploration programs in South Africa, Gabon, and the Gulf Coast transition zone
are targeted for comprehensive studies that will focus on analysis, ranking and
timing of prospects during 1999.
 
NATURAL GAS PROCESSING
 
     The Company historically reflected its ownership interests in and revenues
and expenses related to its natural gas processing facilities as separate items
in the consolidated financial statements while Mesa reported revenues and
expenses from its natural gas processing facilities as oil and gas production
costs. During the last four years, the Company has sold its interests in 12
natural gas processing facilities and now owns interests in seven facilities.
The ownership interest in the remaining gas plant facilities and the related
results of operations from third party gas processed through such facilities are
not material to the Company's financial position. To report the results of gas
processing activities consistently within the financial statements, during 1997,
the Company reclassified the natural gas processing facilities into oil and gas
properties for financial statement purposes and will report all third party
revenues and expenses from its natural gas processing facilities in oil and gas
production costs.
 
                                       35
<PAGE>   36
 
     In 1996, natural gas processing revenues were $23.8 million and natural gas
processing costs were $12.5 million. The average price per Bbl of NGLs was
$15.10 in 1996, while the average price per Mcf of residue gas was $2.15. During
January 1996, the Company realized proceeds of $2.1 million from sales of gas
plants and related assets which resulted in the Company recognizing a net
pre-tax gain of $639 thousand. Additionally, the Company recognized non-cash
pre-tax charges of $1.3 million related to abandonments of certain of the
Company's gas processing facilities and the cancellation of certain gas
processing contracts.
 
GENERAL AND ADMINISTRATIVE EXPENSE
 
     General and administrative expense was $73 million in 1998, $48.8 million
in 1997 and $28.4 million in 1996, representing a 50 percent increase from 1997
to 1998 and a 72 percent increase from 1996 to 1997. The increases from 1996 to
1997, and 1997 to 1998, resulted from the increased size of the Company and
relocation costs caused by the merger between Parker & Parsley and Mesa and the
acquisition of Chauvco.
 
REORGANIZATION
 
     During 1998, the Company announced its plans to sell certain non-strategic
oil and gas fields, its intentions to reorganize its operations by combining its
six domestic operating regions and other cost reduction initiatives intended to
allow Pioneer to better adapt to declining oil and gas commodity price trends.
Specific cost reduction initiatives included the relocation of most of the
Company's administrative services from Midland, Texas to Irving, Texas; the
closings of the Company's regional offices in Oklahoma City, Oklahoma, Corpus
Christi, Texas and Houston, Texas; the termination of 350 employees including
several officer positions; and, further centralization of the Company's
organizational structure. Associated with these initiatives, the Company
recognized a pre-tax reorganization charge of $33.2 million in 1998. In
addition, the Company anticipates that another $5 million of reorganization
charges will be incurred during the first quarter of 1999. See Note N of Notes
to Consolidated Financial Statements in "Item 8. Financial Statements and
Supplementary Data" for specific information regarding reorganization costs paid
in 1998 and costs unpaid as of December 31, 1998.
 
INTEREST EXPENSE
 
     Interest expense was $164.3 million in 1998, $77.6 million in 1997 and
$46.2 million in 1996. The increase in interest expense from 1997 to 1998
primarily reflects the increase in the weighted average outstanding balance of
Company indebtedness that resulted from a full year of debt assumed from Mesa
and Chauvco in 1997 and approximately $190 million of debt incurred to fund 1998
additions to oil and gas properties. The increase from 1996 to 1997 is primarily
the result of an increase in the weighted average outstanding balance of the
Company's indebtedness during 1997 as compared to 1996 due to the additional
debt assumed from Mesa. In addition, the 1997 and 1996 amounts included $6
million and $12 million of interest, respectively, associated with the preferred
stock of the Company's subsidiary, Parker & Parsley Capital LLC, which was
converted to common stock of the Company in July 1997 (see Note I of Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data"). The 1998, 1997 and 1996 amounts also include $1.1 million,
$1.2 million and $1.3 million, respectively, of amortization of capitalized loan
fees.
 
     During each of the years 1998, 1997 and 1996, the Company was a party to
various interest rate swap agreements. As a result, the Company recorded a
reduction in interest expense of $356 thousand, $847 thousand and $787 thousand
for the years ended December 31, 1998, 1997 and 1996, respectively. For a
description of the Company's interest rate swap agreements, see Note J of Notes
to the Consolidated Financial Statements included in "Item 8. Financial
Statements and Supplementary Data".
 
OTHER EXPENSE
 
     Other expense was $39.6 million, $7.1 million and $2.5 million for the
years ended December 31, 1998, 1997 and 1996, respectively. The $32.5 million
increase in other expense from 1997 to 1998 was comprised of several factors,
including a $14.7 million 1998 non-cash, pre-tax, mark-to-market adjustment of
Canadian
 
                                       36
<PAGE>   37
 
dollar to United States dollar currency swaps which were acquired with Chauvco
in December 1997; a $9.6 million 1998 non-cash, pre-tax write-off of deferred
compensation that resulted from certain incentive plan change of control
provisions that were triggered by a 1998 increase in an investment fund's
beneficial ownership in the Company; $4.4 million of other expense items related
to the Company's operations in Argentina and Canada; and, a $2.3 million
increase in bad debt expense. The $4.6 million increase in other expense during
1997 as compared to 1996 primarily resulted from the $5.2 million non-cash,
pre-tax, mark-to-market adjustment of the December 31, 1997 carrying value of
the Company's BTU swap agreement that was originally entered into by Mesa.
During 1998, the Company recognized a $5.8 million non-cash, pre-tax,
mark-to-market adjustment of the carrying value of the BTU swap agreement.
 
     Future mark-to-market adjustments of the Company's non-hedge derivatives
cannot be quantified with any degree of certainty. Such adjustments could
significantly impact the Company's future results of operations, financial
position and cash flows. See Notes F and J to the accompanying Notes to
Consolidated Financial Statements included in "Item 8. Financial Statements and
Supplementary Data" for further discussions pertaining to the incentive plan
change of control provisions and the Company's BTU swap agreement and other
mark-to-market derivatives.
 
INCOME TAXES
 
     For the years ended December 31, 1998, 1997 and 1996, the Company
recognized, exclusive of the tax effect of the 1997 extraordinary loss, a
consolidated tax provision of $15.6 million, a tax benefit of $500.3 million and
a tax provision of $60.1 million, respectively. The tax provision for the year
ended December 31, 1998 includes a $271.1 million deferred tax valuation charge
to reduce the carrying value of the Company's deferred tax assets. During the
fourth quarter of 1998, the Company reviewed its deferred tax assets, and in
light of the current economic conditions in the oil and gas industry, and the
Company's outlook for future commodity prices, and the Company's performance
over the past two years; the Company believes that certain of its net operating
losses may expire unused, and accordingly, has established a valuation allowance
against them.
 
     The Company's annual income tax provisions or benefits were determined from
the separate tax calculation prepared for each tax jurisdiction in which the
Company is subject to income taxes. For 1998, 1997 and 1996, the Company had
effective total tax rates of approximately two percent, 36 percent and 30
percent, respectively. See Note O of Notes to Consolidated Financial Statements
included in "Item 8. Financial Statements and Supplementary Data" for further
discussion of the Company's income tax provision and benefits.
 
EXTRAORDINARY ITEMS
 
     On December 18, 1997, the Company completed a cash tender offer for a
significant portion of the 11 5/8% senior subordinated discount notes due 2006
and the 10 5/8% senior subordinated notes due 2006 (the "10 5/8% Notes")
(collectively, the "Subordinated Notes") assumed from Mesa for a redemption
price of $829.90 and $1,171.40, respectively, per $1,000 tendered plus any
interest accrued on the 10 5/8% Notes (the "Tender Offer"). As a result of the
Tender Offer, the Company recognized an extraordinary loss on early
extinguishment of debt of $11.9 million (net of a related tax benefit of $6.4
million) during the fourth quarter of 1997. The Company financed the purchase
price of the Subordinated Notes tendered in the offer with borrowings under its
bank credit facility.
 
     The accompanying Consolidated Statement of Operations and Comprehensive
Income (Loss) for the year ended December 31, 1997 also includes a $1.5 million
(net of a related tax benefit of $800 thousand) non-cash charge for an
extraordinary loss on early extinguishment of debt resulting from the mergers.
This extraordinary loss relates to capitalized issuance fees associated with
Parker & Parsley's previously existing bank credit facility, which was replaced
by a new credit facility agreement for the Company.
 
                                       37
<PAGE>   38
 
CAPITAL COMMITMENTS, CAPITAL RESOURCES AND LIQUIDITY
 
     CAPITAL COMMITMENTS. The Company's primary needs for cash are for
exploration, development and acquisitions of oil and gas properties, repayment
of principal and interest on outstanding indebtedness and working capital
obligations.
 
     The Company's cash expenditures during 1998, 1997 and 1996 for additions to
oil and gas properties (including individual property acquisitions, but not
including company acquisitions) totaled $507.3 million, $428.6 million and
$219.4 million, respectively. The 1998 amount includes $450.3 million of
development and exploratory drilling and seismic costs, of which $332.0 million,
or 74 percent, were development expenditures. During 1998, $308.2 million, or 68
percent, of the Company's drilling and seismic expenditures occurred in the
United States, of which $167.4 million, or 54 percent, was expended in the Gulf
Coast area and $112.6 million, or 37 percent, was expended in the Permian Basin
area. Also, during 1998, the Company expended $142.1 million, or 32 percent, of
its drilling and seismic capital in its international regions, located in Canada
($65.8 million, or 15 percent of worldwide drilling and seismic expenditures),
Argentina ($57.5 million, or 13 percent of worldwide drilling and seismic
expenditures) and other international areas ($18.8 million, or four percent of
worldwide drilling and seismic expenditures), including South Africa and Gabon.
The 1997 amount includes $292.6 million for development and exploratory drilling
when, as in 1996, the Company's drilling activities were focused primarily in
the Spraberry field of the Permian Basin. Significant drilling expenditures in
1997 included $99.0 million in the unitized portion of the Spraberry field of
the Permian Basin (including $47.6 million in the Driver unit, $12.7 million in
the Preston unit, $12.6 million in the Shackelford unit, $12.2 million in the
North Pembrook unit and $10.5 million in the Merchant unit), $14.9 million in
other portions of the Spraberry field, $46.5 million in other areas of the
Permian Basin, $91.3 million in the onshore and offshore Gulf Coast area, $29.9
million in the Mid Continent area and $11.0 million in Argentina and Guatemala.
 
     The Company's 1999 capital expenditure budget has been set at $100 million,
reflecting planned expenditure reductions in support of the Company's intention
to reduce outstanding indebtedness and to increase financial flexibility.
Capital expenditures for 1999 are expected to include $75 million for
exploitation activities and $25 million for exploration activities. The Company
budgets its capital expenditures based on projected internally-generated cash
flows and routinely adjusts the level of its capital expenditures in response to
anticipated changes in cash flows.
 
     Funding for the Company's working capital obligations is provided by
internally-generated cash flow. Funding for the repayment of principal and
interest on outstanding debt and the Company's capital expenditure program may
be provided by any combination of internally-generated cash flow, proceeds from
the disposition of non-strategic assets or alternative financing sources as
discussed in "Capital Resources" below.
 
     CAPITAL RESOURCES. The Company's primary capital resources are net cash
provided by operating activities, proceeds from financing activities and
proceeds from sales of non-strategic assets. The Company expects that these
resources will be sufficient to fund its capital commitments in 1999.
 
  Operating Activities
 
     Net cash provided by operating activities during 1998, 1997 and 1996 were
$314.1 million, $228.2 million and $230.1 million, respectively. Net cash
provided by operating activities in 1998 increased 38 percent over that of 1997
as a result of the increased production realized from the properties acquired
from Mesa and Chauvco, partially offset by declining commodity prices and
increased general and administrative expenses, reorganization expenditures, and
interest expense. Net cash provided by operating activities in 1997 was
comparable to that of 1996. Increased production in 1997 was offset by increased
general and administrative expenses and interest expenses and the payment of
certain liabilities assumed from Mesa, including severance payments made to
former Mesa employees.
 
                                       38
<PAGE>   39
 
  Financing Activities
 
     As described more fully in Note E of Notes to Consolidated Financial
Statements included in "Item 8. Financial Statements and Supplementary Data", as
of December 31, 1998 the Company was a borrower under three credit facility
agreements with a syndicate of banks which provided for a total bank credit
facility of $1.4 billion as of December 31, 1998. The Company had an outstanding
balance under its Primary Facility at December 31, 1998 of $993.6 million
(including outstanding, undrawn letters of credit of $19.6 million), leaving
approximately $81 million of unused borrowing base available as of December 31,
1998. The Company had no outstanding borrowings under its 364-day Facility as of
December 31, 1998, leaving $85 million of borrowing capacity unused on that
date. At December 31, 1998, the Company also had $276.0 million of term loan
borrowings outstanding under its Canadian Facility, representing the total
borrowing capacity under the Canadian Facility. During the first quarter of
1999, the Company and the participating banks amended the Credit Facilities
whereby the Primary Facility and the Canadian Facility were consolidated; the
total loan commitments under the Credit Facilities were reduced by $495 million
by December 31, 1999; the interest rate on LIBOR Rate advances increased to a
maximum of 350 basis points; and, certain other Credit Facility amendments as
described in "1999 Outlook," above.
 
     At December 31, 1998, the Company had four other outstanding significant
debt issuances. Such debt issuances consist of (i) $150 million aggregate
principal amount of 8 7/8% senior notes issued by Parker & Parsley in 1995 and
due in 2005 (carrying value of $150.0 million); (ii) $150 million aggregate
principal amount of 8 1/4% senior notes issued by Parker & Parsley in 1995 and
due in 2007 (carrying value of $149.4 million); (iii) $350 million aggregate
principal amount of 6 1/2% senior notes issued by Pioneer in 1998 and due in
2008 (carrying value of $348.4 million); and, (iv) $250 million aggregate
principal amount of 7 1/5% senior notes issued by Pioneer in 1998 and due in
2028 (carrying value of $249.9 million).
 
     The weighted average interest rate for the year ended December 31, 1998 on
the Company's indebtedness was 7.16 percent as compared to 7.04 percent for the
year ended December 31, 1997 and 7.83 percent for the year ended December 31,
1996 (taking into account the effect of interest rate swaps).
 
     As the Company continues to pursue its strategy, it may utilize alternative
financing sources, including the issuance for cash of fixed rate long-term
public debt, convertible securities or preferred stock. The Company may also
issue securities in exchange for oil and gas properties, stock or other
interests in other oil and gas companies or related assets. Additional
securities may be of a class preferred to common stock with respect to such
matters as dividends and liquidation rights and may also have other rights and
preferences as determined by the Company's Board of Directors.
 
  Sales of Non-strategic Assets
 
     During 1998, 1997 and 1996, proceeds from the sale of non-strategic assets
totaled $21.9 million, $115.7 million and $58.4 million, respectively. In
addition, during 1996, the Company sold certain subsidiaries resulting in cash
proceeds of $183.2 million (see Note L of Notes to Consolidated Financial
Statements included in "Item 8. Financial Statements and Supplementary Data").
The proceeds from these sales were primarily utilized to reduce the Company's
outstanding bank indebtedness and for general working capital purposes.
 
     As is more fully discussed in "1999 Outlook", above, the Company announced
its intentions to sell certain domestic non-strategic properties for gross
proceeds of $335 million. These properties represent approximately 10 percent of
the Company's reserves at December 31, 1998. Although the Company plans to
complete this sale during the first quarter of 1999, there can be no assurance
that the buyer will be able to consummate the transaction. The Company
anticipates that it will continue to sell non-strategic properties from time to
time to reduce outstanding indebtedness, increase capital resources available
for other activities and to achieve operating and administrative efficiencies
and improved profitability.
 
     In January 1999, the Company announced its intentions to divest, during
1999 and 2000, non-strategic properties for gross divestment proceeds, including
the currently pending divestiture, of $500 million to $600 million. There can be
no assurances that the Company will be successful negotiating or completing such
 
                                       39
<PAGE>   40
 
divestitures within the 1999 to 2000 time frame. The consummation of the
Company's 1999 and 2000 divestiture plan is entirely dependent on finding one or
more willing purchasers who have the financial wherewithal to complete such
purchases. Until such purchasers are found, the Company may reevaluate its
portfolio of properties and at any time may adjust its plans concerning
divestitures. As a result, there can be no assurance that the divestiture of any
or all of these properties will be completed or that the estimated proceeds will
be realized.
 
     LIQUIDITY. At December 31, 1998, the Company had $59.2 million of cash and
cash equivalents on hand, compared to $71.7 million at December 31, 1997. The
Company's ratio of current assets to current liabilities was .38 at December 31,
1998 and 1.18 at December 31, 1997. The decline in the ratio is primarily
reflective of $306.5 million of current maturities of long-term debt as of
December 31, 1998, including required reductions in borrowings under the
Company's Credit Facilities and other current debt obligations. See "1999
Outlook -- Credit facilities," above, and Note E of Notes to Consolidated
Financial Statements included in "Item 8. Financial Statements and Supplementary
Data" for further discussions regarding amendments to the Company's Credit
Facilities.
 
ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
 
     The following quantitative and qualitative information is provided about
financial instruments to which the Company is a party as of December 31, 1998,
and from which the Company may incur future earnings gains or losses from
changes in market interest rates, foreign exchange rates, commodity prices or
common stock prices. Although certain derivative contracts that the Company is a
party to do not qualify as hedges, the Company does not enter into derivative or
other financial instruments for trading purposes.
 
QUANTITATIVE DISCLOSURES
 
     INTEREST RATE SENSITIVITY. The following table provides information, in
United States dollar equivalent amounts, about the Company's derivative
financial instruments and other financial instruments that the Company is a
party to as of December 31, 1998 which are sensitive to changes in interest
rates. For debt obligations, the table presents maturities by expected maturity
dates together with the weighted average interest rates expected to be paid on
the debt, given current contractual terms and market conditions. For fixed rate
debt, the weighted average interest rate represents the contractual fixed rates
that the Company is obligated to periodically pay on the debt; for variable rate
debt, the average interest rate represents the average rates being paid on the
debt projected forward proportionate to the forward yield curve for United
States treasury securities. For the Canadian dollar denominated financial
instruments, the most recent average forward United States dollar to Canadian
dollar exchange rate is presented for the readers' information. For interest
rate derivatives that the Company is a party to and that are related to the
Company's total debt, the notional contractual amounts are presented together
with the average rates paid and received by the Company.
 
                                       40
<PAGE>   41
 
                       PIONEER NATURAL RESOURCES COMPANY
                           INTEREST RATE SENSITIVITY
       DERIVATIVE AND OTHER FINANCIAL INSTRUMENTS AS OF DECEMBER 31, 1998
 
<TABLE>
<CAPTION>
                                 1999      2000      2001       2002       2003     THEREAFTER     TOTAL      FAIR VALUE
                               --------   -------   -------   --------   --------   ----------   ----------   ----------
                                               (IN THOUSANDS EXCEPT INTEREST AND FOREIGN EXCHANGE RATES)
<S>                            <C>        <C>       <C>       <C>        <C>        <C>          <C>          <C>
Total Debt:
  U.S. dollar denominated
    maturities:
    Fixed rate debt..........  $    330   $    --   $    --   $  1,508   $  1,447    $932,948    $  936,233   $  743,701(1)
    Weighted average interest
      rate...................      7.50%     7.50%     7.50%      7.50%      7.50%       7.50%
    Variable rate debt.......  $306,191   $    --   $    --   $932,841                           $1,239,032   $1,239,032
    Average interest rate....      5.85%     5.87%     5.89%      5.92%
Interest Rate Derivatives
  Related to Total Debt:
  U.S. dollar denominated
    hedge derivatives:
    Notional amount of
      interest rate
      swaps(2)...............  $150,000                                                                       $    1,046
    Average variable rate
      paid...................      5.18%
    Average fixed rate
      received...............      6.62%
  Canadian dollar denominated
    non-hedge derivatives:
    Notional amount of
      interest rate cap(3)...  $122,436                                                                       $      (80)
    Rate paid when index is
      below 8%...............      0.28%
    Average forward U.S.
      dollar to Canadian
      dollar exchange rate...    0.6671
</TABLE>
 
- ---------------
 
(1) Excludes $6.8 million of 10 5/8% notes due 2006 and $22.5 million of 11 5/8%
    notes due 2006 for which fair values were not practicable to derive.
 
(2) $75 million notional amount of the interest rate swaps mature May 7, 1999;
    $50 million notional amount of the interest rate swaps mature June 4, 1999;
    and, $25 million notional amount of the interest rate swaps mature June 11,
    1999.
 
(3) The Canadian dollar denominated interest rate cap matures August, 1999.
 
     FOREIGN EXCHANGE RATE SENSITIVITY. The following table provides
information, in United States dollar equivalent amounts, about the Company's
derivative financial instruments and other financial instruments that the
Company is a party to as of December 31, 1998 and that are sensitive to changes
in foreign exchange rates. The table provides information regarding the notional
amounts of the Company's Canadian dollar denominated interest rate cap and
foreign currency swap derivative contracts, including rates paid and received by
the Company and forward currency exchange rates.
 
                                       41
<PAGE>   42
 
                       PIONEER NATURAL RESOURCES COMPANY
                       FOREIGN EXCHANGE RATE SENSITIVITY
       DERIVATIVE AND OTHER FINANCIAL INSTRUMENTS AS OF DECEMBER 31, 1998
 
<TABLE>
<CAPTION>
                                       1999      2000      2001      2002       2003     THEREAFTER    TOTAL     FAIR VALUE
                                     --------   -------   -------   -------   --------   ----------   --------   ----------
                                                   (IN THOUSANDS EXCEPT INTEREST AND FOREIGN EXCHANGE RATES)
<S>                                  <C>        <C>       <C>       <C>       <C>        <C>          <C>        <C>
Non-hedge Interest Rate Derivatives
  Related to Total Debt:
  Canadian dollar denominated
    derivatives:
    Notional amount of interest
      rate cap(1)..................  $122,436                                                         $122,436    $    (80)
    Rate paid when index is below
      8%...........................      0.28%
    Average forward U.S. dollar to
      Canadian dollar exchange
      rate.........................    0.6671
Non-hedge Foreign Exchange Rate
  Derivatives:
  Notional amount of foreign
    currency swaps(2)..............  $ 72,000   $72,000                                               $144,000    $(15,350)
  Fixed Canadian to U.S. dollar
    rate paid......................    1.3670    1.3606
  Average forward Canadian dollar
    to U.S. dollar exchange rate
    payable........................    1.4990    1.4963
</TABLE>
 
- ---------------
 
(1) The Canadian dollar denominated interest rate cap matures August 1999.
 
(2) The foreign exchange rate swaps mature in October and December 2000.
 
     COMMODITY PRICE SENSITIVITY. The following table provides information, in
United States dollar equivalent amounts, about the Company's derivative
financial instruments that the Company is a party to as of December 31, 1998 and
that are sensitive to changes in natural gas and crude oil commodity prices. The
table segregates hedge derivative contracts from those that do not qualify as
hedges. As shown in the table, the Company has entered into swap contracts
whereby a fixed price is established for a notional amount of sales volumes.
Additionally, the Company has entered into collar contracts that provide a floor
price for the Company on a notional amount of sales volumes while allowing some
additional price participation for the Company if the relevant index prices
close above the floor price. The Company also has entered into collar contracts
with short put options that differ from other collar contracts by virtue of the
short put option price, below which the Company's realized price will exceed
variable market prices by approximately $.30 per MMBtu. The Company's agreement
to swap the NYMEX gas price for 10 percent of the NYMEX oil price (the "BTU
Swap") was acquired through the merger with Mesa. Under the terms of the BTU
Swap, the Company receives 10 percent of the NYMEX oil price and pays the NYMEX
gas price on 13,036 notional MMBtu daily volume. See Notes B, C and J of Notes
to Consolidated Financial Statements included in "Item 8. Financial Statements
and Supplementary Data" for a description of the accounting procedures followed
by the Company relative to hedge and non-hedge derivative financial instruments
and for specific information regarding the terms of the Company's derivative
financial instruments that are sensitive to changes in natural gas and crude oil
commodity prices.
 
                                       42
<PAGE>   43
 
                       PIONEER NATURAL RESOURCES COMPANY
                          COMMODITY PRICE SENSITIVITY
       DERIVATIVE AND OTHER FINANCIAL INSTRUMENTS AS OF DECEMBER 31, 1998
 
<TABLE>
<CAPTION>
                                      1999      2000      2001      2002      2003     THEREAFTER    TOTAL    FAIR VALUE
                                    --------   -------   -------   -------   -------   ----------   -------   ----------
                                                          (IN THOUSANDS EXCEPT VOLUMES AND PRICES)
<S>                                 <C>        <C>       <C>       <C>       <C>       <C>          <C>       <C>
Natural Gas Hedge Derivatives(1):
  Average daily notional MMBtu
    volumes(2):
    Swap contracts(3).............   137,044    35,000                                              172,044    $ 17,827
    Weighted average MMBtu fixed
      price.......................  $   2.21   $  2.35
    Collar option contracts.......    33,400                                                         33,400    $    323
    Weighted average short call
      MMBtu ceiling price.........  $   2.56
    Weighted average long put
      MMBtu floor price...........  $   1.91
    Collar option contracts with
      short puts(4)...............   114,286    93,074                                              207,360    $  8,398
    Weighted average short call
      MMBtu ceiling price.........  $   2.64   $  2.75
    Weighted average long put
      MMBtu contingent floor
      price.......................  $   2.12   $  2.14
    Weighted average short put
      MMBtu price below which
      floor becomes variable......  $   1.82   $  1.84
Natural Gas non-hedge Derivatives:
  Daily notional MMBtu volumes
    under agreement to swap NYMEX
    gas price for 10 percent of
    NYMEX WTI price...............    13,036    13,036    13,036    13,036    13,036     13,036      78,216    $(15,172)
    Average forward NYMEX gas
      prices......................  $   1.97   $  2.17   $  2.25   $  2.34   $  2.39    $  2.45
    Average forward NYMEX oil
      prices......................  $  13.00   $ 14.75   $ 16.00   $ 16.75   $ 17.45    $ 17.88
</TABLE>
 
- ---------------
 
(1) When necessary, to minimize basis risk the Company enters into basis swaps
    to connect the index price of the hedging instrument from a NYMEX index to
    an index which reflects the geographic area of production. The Company
    considers these basis swaps as part of the associated swap and option
    contracts and, accordingly, the effects of the basis swaps have been
    presented together with the associated contracts.
 
(2) See Note J of Notes to Consolidated Financial Statements included in "Item
    8. Financial Statements and Supplementary Data" for hedge volumes and
    weighted average prices by calendar quarter for 1999 and 2000.
 
(3) Certain counterparties to the 1999 and 2000 swap contracts have the
    contractual right to extend 35,000 MMBtu per day for one additional year at
    prices of $2.40 and $2.41 per MMBtu, respectively.
 
(4) 65,000 MMBtu per day of the 1999 collar option contracts with short puts are
    extendable at the option of the counterparties for a period of one year at
    average per MMBtu prices of $2.79, $2.18 and $1.88 for the short call, long
    put and short put, respectively. 75,000 MMBtu per day of the 2000 collar
    option contracts with short puts are extendable at the option of the
    counterparties at average per MMBtu prices of $2.90, $2.20 and $1.90 for the
    short call, long put and short put, respectively.
 
     OTHER PRICE SENSITIVITY. The following table provides information about the
Company's investment in common stock of Costilla Energy Inc. ("Costilla"). The
Company acquired three million shares of Costilla in partial payment of the
option fees associated with the irrevocable option sold to Costilla in December
1998, the terms of which allow Costilla to acquire certain assets of the
Company. Costilla has the option of repurchasing its common shares from the
Company, prior to May 31, 1999, for an aggregate purchase price of $13 million.
See Trends and Uncertainties -- Asset Dispositions included in "Item 7.
Management's Discussion and Analysis of Financial Condition and Results of
Operations" for a discussion with specific information regarding the irrevocable
option agreement sold to Costilla.
 
                                       43
<PAGE>   44
 
                       PIONEER NATURAL RESOURCES COMPANY
                            OTHER PRICE SENSITIVITY
       DERIVATIVE AND OTHER FINANCIAL INSTRUMENTS AS OF DECEMBER 31, 1998
 
<TABLE>
<CAPTION>
                                             1999     2000     2001     2002     2003    THEREAFTER   TOTAL   FAIR VALUE
                                            ------   ------   ------   ------   ------   ----------   -----   ----------
                                                              (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
<S>                                         <C>      <C>      <C>      <C>      <C>      <C>          <C>     <C>
Total Marketable Securities:
  Common shares of Costilla Energy Inc....   3,000                                                    3,000    $12,000
  Market value per share of Costilla
    Energy Inc. common stock on December
    31, 1998..............................  $ 4.00
Option Sold:
  Option to purchase 3 million shares of
    Costilla Energy Inc. common stock from
    the Company for $13 million:
      Total option shares.................   3,000                                                    3,000           (1)
      Option price per share..............  $ 4.25
      Market value per share of Costilla
        Energy Inc. common stock on
        December 31, 1998.................  $ 4.00
</TABLE>
 
- ---------------
 
(1) Determination of fair value not practicable.
 
QUALITATIVE DISCLOSURES
 
     NON-DERIVATIVE FINANCIAL INSTRUMENTS. The Company is a borrower under fixed
rate and variable rate debt instruments that give rise to interest rate and
foreign exchange rate risk. The Company's objective in borrowing under fixed or
variable rate debt is to satisfy capital requirements while minimizing the
Company's costs of capital. To realize its objectives, the Company borrows under
fixed and variable rate debt instruments, based on the availability of capital,
market conditions and hedge opportunities. See Note E of Notes to Consolidated
Financial Statements included in "Item 8. Financial Statements and Supplementary
Data" for a discussion relative to the Company's debt instruments.
 
     The Company received three million shares of Costilla common stock in
partial payment of the fees associated with an irrevocable option sold to
Costilla to purchase certain oil and gas properties of the Company prior to
April 1, 1999. The Company purchased the Costilla common shares as an
accommodation of the larger transaction with Costilla involving the contemplated
sale of certain of the Company's oil and gas properties. The Company did not
purchase the Costilla shares for trading purposes, although the Company has the
option of selling the shares to a third party if Costilla does not repurchase
them. Costilla has the contractual right to repurchase the shares prior to May
31, 1999, for an aggregate purchase price of $13 million, or $4.25 per share.
The Company does not normally, nor does it contemplate, investing in marketable
securities for trading purposes.
 
     DERIVATIVE FINANCIAL INSTRUMENTS. The Company has entered into interest
rate, foreign exchange rate and commodity price derivative contracts to hedge
interest rate, foreign exchange rate and commodity price risks. Although the
Company has succeeded Mesa and Chauvco as a party to interest rate, foreign
exchange rate and commodity price derivative contracts that do not qualify as
hedges, the Company's policy is not to enter into derivative contracts for
trading purposes.
 
  Crude oil hedge derivatives
 
     All material purchase contracts governing the Company's oil production are
tied directly or indirectly to NYMEX prices. As a result, from time to time the
Company hedges its oil production using contracts tied to the NYMEX prices. The
average oil prices per Bbl that the Company reports include the effects of oil
quality, gathering and transportation costs and the net effect of the oil
hedges. As of December 31, 1998, the Company was not a party to any crude oil
hedge derivatives.
 
                                       44
<PAGE>   45
 
  Natural gas liquids hedge derivatives
 
     The Company from time to time hedges natural gas liquids based on actual
production prices in order to mitigate some of the volatility associated with
NYMEX pricing. As of December 31, 1998, the Company was not a party to natural
gas liquids derivatives.
 
  Natural gas hedge derivatives
 
     The Company employs a policy of hedging a portion of its gas production
based on the index price upon which the gas is actually sold in order to
mitigate the basis risk between NYMEX prices and actual index prices. As of
December 31, 1998, the Company has hedged a portion of its gas price risk with
swap contracts that establish a fixed floor price for a notional amount of sales
volume; collar contracts that provide a fixed floor price but allow the Company
to participation, within a contractual range, in index prices if they close
above the contractual floor price; and, collar contracts with short put options,
the terms of which are similar to collar contracts except that the Company's
floor price on a notional sales volume becomes variable, at an above market
differential, if market prices fall below the short put index price. The average
gas prices per Mcf that the Company reports includes the effects of Btu content,
gathering and transportation costs, gas processing and shrinkage and the net
effect of the gas hedges.
 
  Non-hedge derivatives
 
     As of December 31, 1998, the Company, through its merger with Mesa and
acquisition of Chauvco, is a party to the Canadian denominated interest rate cap
agreement, foreign exchange rate swaps and the BTU Swap that are described more
fully in Quantitative Disclosures, above, and Note J of Notes to Consolidated
Financial Statements included in "Item 8. Financial Statements and Supplementary
Data". These financial instruments do not qualify as hedges of interest rate,
foreign exchange rate or commodity price risk.
 
     The Company has a policy and strategy, as of December 31, 1998, to only
enter into interest rate, foreign exchange rate or commodity price derivative
instruments that qualify as hedges of its existing interest rate, foreign
exchange rate or commodity price risks. The Company's derivative instruments
that were initiated by Mesa and Chauvco will be allowed to mature by their terms
unless the Company encounters an opportunity, under terms more favorable than
are presently available, to terminate the contracts prior to their contractual
maturities. See Notes B, C and J of Notes to Consolidated Financial Statements
included in "Item 8. Financial Statements and Supplementary Data" for further
discussions relative to the Company's objectives and general strategies
associated with its hedge instruments.
 
     As of December 31, 1998, the Company's primary risk exposures associated
with financial instruments to which it is a party include natural gas and crude
oil price volatility, interest rate volatility and Canadian dollar to United
States dollar foreign exchange rate volatility. The Company's primary risk
exposures associated with financial instruments have not changed significantly
since December 31, 1997.
 
                                       45
<PAGE>   46
 
ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA
 
                   INDEX TO CONSOLIDATED FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                               PAGE
                                                               ----
<S>                                                            <C>
Consolidated Financial Statements of Pioneer Natural
  Resources Company:
  Independent Auditors' Reports.............................   47
  Consolidated Balance Sheets as of December 31, 1998 and
     1997...................................................   49
  Consolidated Statements of Operations and Comprehensive
     Income (Loss) for the Years Ended December 31,1998,
     1997 and 1996..........................................   50
  Consolidated Statements of Stockholders' Equity for the
     Years Ended December 31, 1998, 1997 and 1996...........   51
  Consolidated Statements of Cash Flows for the Years Ended
     December 31, 1998, 1997 and 1996.......................   52
  Notes to Consolidated Financial Statements................   53
  Unaudited Supplementary Information.......................   88
</TABLE>
 
                                       46
<PAGE>   47
 
                          INDEPENDENT AUDITORS' REPORT
 
The Board of Directors and Shareholders
Pioneer Natural Resources Company:
 
     We have audited the accompanying consolidated balance sheet of Pioneer
Natural Resources Company and subsidiaries as of December 31, 1998, and the
related consolidated statements of operations and comprehensive income (loss),
stockholders' equity, and cash flows for the year then ended. These financial
statements are the responsibility of the Company's management. Our
responsibility is to express an opinion on these financial statements based on
our audit.
 
     We conducted our audit in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audit provides a reasonable basis for our opinion.
 
     In our opinion, the consolidated financial statements referred to above
present fairly, in all material respects, the consolidated financial position of
Pioneer Natural Resources Company and subsidiaries at December 31, 1998, and the
consolidated results of its operations and its cash flows for the year then
ended in conformity with generally accepted accounting principles.
 
                                     Ernst & Young LLP
 
Dallas, Texas
February 2, 1999, except for Note E
as to which the date is March 19, 1999
 
                                       47
<PAGE>   48
 
                          INDEPENDENT AUDITORS' REPORT
 
The Board of Directors and Stockholders
Pioneer Natural Resources Company:
 
     We have audited the consolidated balance sheet of Pioneer Natural Resources
Company and subsidiaries as of December 31, 1997, and the related consolidated
statements of income and comprehensive income, shareholders' equity, and cash
flows for the years ended December 31, 1997 and 1996. These consolidated
financial statements are the responsibility of the Company's management. Our
responsibility is to express an opinion on these consolidated financial
statements based on our audits.
 
     We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
     In our opinion, the consolidated financial statements referred to above
present fairly, in all material respects, the financial position of Pioneer
Natural Resources Company and subsidiaries as of December 31, 1997, and the
results of their operations and their cash flows for each of the years in the
two-year period ended December 31, 1997, in conformity with generally accepted
accounting principles.
 
                                          KPMG LLP
 
Midland, Texas
February 13, 1998
 
                                       48
<PAGE>   49
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                          CONSOLIDATED BALANCE SHEETS
                       (IN THOUSANDS, EXCEPT SHARE DATA)
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                                                    DECEMBER 31,
                                                              ------------------------
                                                                 1998          1997
                                                              -----------   ----------
<S>                                                           <C>           <C>
Current assets:
  Cash and cash equivalents.................................  $    59,221   $   71,713
  Accounts receivable:
     Trade, net.............................................       33,384       75,432
     Affiliates.............................................        3,657           --
     Oil and gas sales......................................       73,479      116,500
  Inventories...............................................       15,221       13,576
  Deferred income taxes.....................................        7,100       16,900
  Other current assets......................................        9,926       14,067
                                                              -----------   ----------
          Total current assets..............................      201,988      308,188
                                                              -----------   ----------
Property, plant and equipment, at cost:
  Oil and gas properties, using the successful efforts
methods of accounting:
     Proved properties......................................    3,621,630    3,575,971
     Unproved properties....................................      342,589      545,074
  Accumulated depletion, depreciation and amortization......     (930,111)    (605,203)
                                                              -----------   ----------
                                                                3,034,108    3,515,842
                                                              -----------   ----------
Deferred income taxes.......................................       96,800      206,400
Other property and equipment, net...........................       55,010       44,017
Other assets, net...........................................       93,408       78,543
                                                              -----------   ----------
                                                              $ 3,481,314   $4,152,990
                                                              ===========   ==========
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Current maturities of long-term debt......................  $   306,521   $    5,791
  Accounts payable:
     Trade..................................................       94,937      176,697
     Affiliates.............................................        4,492        9,994
  Accrued interest payable..................................       33,194       13,697
  Other current liabilities.................................       87,688       55,373
                                                              -----------   ----------
          Total current liabilities.........................      526,832      261,552
                                                              -----------   ----------
Long-term debt, less current maturities.....................    1,868,744    1,943,718
Other noncurrent liabilities................................      232,461      180,275
Deferred income taxes.......................................       64,200      218,600
Stockholders' equity:
  Preferred stock, $.01 par value; 100,000,000 shares
     authorized; one share issued and outstanding...........           --           --
  Common stock, $.01 par value; 500,000,000 shares
     authorized; 100,833,615 and 101,037,562 shares issued
     at December 31, 1998 and 1997, respectively............        1,008        1,010
  Additional paid-in capital................................    2,347,996    2,359,992
  Treasury stock, at cost; 537,392 and 591 shares at
     December 31, 1998 and 1997, respectively...............      (10,388)         (21)
  Unearned compensation.....................................           --      (16,196)
  Retained deficit..........................................   (1,552,442)    (795,940)
  Accumulated other comprehensive income (loss):
     Cumulative translation adjustment......................        2,903           --
                                                              -----------   ----------
          Total stockholders' equity........................      789,077    1,548,845
Commitments and contingencies
                                                              -----------   ----------
                                                              $ 3,481,314   $4,152,990
                                                              ===========   ==========
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                       49
<PAGE>   50
 
                       PIONEER NATURAL RESOURCES COMPANY
 
     CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                                 YEAR ENDED DECEMBER 31,
                                                           -----------------------------------
                                                              1998         1997         1996
                                                           ----------   -----------   --------
<S>                                                        <C>          <C>           <C>
Revenues:
  Oil and gas............................................  $  711,492   $   536,782   $396,931
  Natural gas processing.................................          --            --     23,814
  Interest and other.....................................      10,452         4,278     17,458
  Gain (loss) on disposition of assets, net..............        (445)        4,969     97,140
                                                           ----------   -----------   --------
                                                              721,499       546,029    535,343
                                                           ----------   -----------   --------
Costs and expenses:
  Oil and gas production.................................     223,551       144,170    110,334
  Natural gas processing.................................          --            --     12,528
  Depletion, depreciation and amortization...............     337,308       212,435    112,134
  Impairment of oil and gas properties...................     459,519     1,356,390         --
  Exploration and abandonments...........................     121,858        77,160     23,030
  General and administrative.............................      73,000        48,763     28,363
  Reorganization.........................................      33,199            --         --
  Interest...............................................     164,285        77,550     46,155
  Other..................................................      39,605         7,124      2,451
                                                           ----------   -----------   --------
                                                            1,452,325     1,923,592    334,995
                                                           ----------   -----------   --------
Income (loss) before income taxes and extraordinary
  item...................................................    (730,826)   (1,377,563)   200,348
Income tax benefit (provision)...........................     (15,600)      500,300    (60,100)
                                                           ----------   -----------   --------
Income (loss) before extraordinary item..................    (746,426)     (877,263)   140,248
Extraordinary item -- loss on early extinguishment of
  debt, net of tax.......................................          --       (13,408)        --
                                                           ----------   -----------   --------
Net income (loss)........................................    (746,426)     (890,671)   140,248
Other comprehensive income (loss):
  Currency translation adjustment........................       2,903            --     (3,303)
                                                           ----------   -----------   --------
Comprehensive income (loss)..............................  $ (743,523)  $  (890,671)  $136,945
                                                           ==========   ===========   ========
Income (loss) per share:
  Basic:
     Income (loss) before extraordinary item.............  $    (7.46)  $    (16.88)  $   3.95
     Extraordinary item..................................          --          (.26)        --
                                                           ----------   -----------   --------
     Net income (loss)...................................  $    (7.46)  $    (17.14)  $   3.95
                                                           ==========   ===========   ========
  Diluted:
     Income (loss) before extraordinary item.............  $    (7.46)  $    (16.88)  $   3.47
     Extraordinary item..................................          --          (.26)        --
                                                           ----------   -----------   --------
     Net income (loss)...................................  $    (7.46)  $    (17.14)  $   3.47
                                                           ==========   ===========   ========
Dividends declared per share.............................  $      .10   $       .10   $    .10
                                                           ==========   ===========   ========
Weighted average shares outstanding......................     100,055        51,973     35,475
                                                           ==========   ===========   ========
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                       50
<PAGE>   51
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                            ACCUM. OTHER
                                           ADDITIONAL              UNEARNED    RETAINED     COMPREHENSIVE       TOTAL
                                  COMMON    PAID-IN     TREASURY   COMPEN-     EARNINGS        INCOME       STOCKHOLDERS'
                                  STOCK     CAPITAL      STOCK      SATION     (DEFICIT)       (LOSS)          EQUITY
                                  ------   ----------   --------   --------   -----------   -------------   -------------
<S>                               <C>      <C>          <C>        <C>        <C>           <C>             <C>
Balance at January 1, 1996......  $ 364    $  452,718   $ (6,844)  $ (2,055)  $   (36,491)     $ 3,303       $  410,995
Exercise of long-term incentive
  plan stock options............      5         6,899         --         --            --           --            6,904
Restricted shares awarded.......     --         1,091         --     (1,199)           --           --             (108)
Restricted shares forfeited.....     --           (35)       (13)        48            --           --               --
Tax benefits related to stock
  and option awards.............     --         2,200         --         --            --           --            2,200
Purchase of treasury stock......     --            --    (24,671)        --            --           --          (24,671)
Amortization of unearned
  compensation..................     --            --         --      1,581            --           --            1,581
Net income......................     --            --         --         --       140,248           --          140,248
Dividends ($.10 per share)......     --            --         --         --        (3,550)          --           (3,550)
Other comprehensive income
  (loss):
  Currency translation
    adjustment..................     --            --         --         --            --       (3,303)          (3,303)
                                  ------   ----------   --------   --------   -----------      -------       ----------
Balance at December 31, 1996....    369       462,873    (31,528)    (1,625)      100,207           --          530,296
                                  ------   ----------   --------   --------   -----------      -------       ----------
Common stock issued:
  Acquisition of MESA, Inc......    318       982,248         --         --            --           --          982,566
  Acquisition of Chauvco
    Resources, Ltd..............    249       688,081         --         --            --           --          688,330
  Acquisition of properties.....     16        44,857         --         --            --           --           44,873
Exercise of long-term incentive
  plan stock options............      5        11,591         --         --            --           --           11,596
Cancellation of treasury
  shares........................    (19)      (34,441)    34,460         --            --           --               --
Exchange of preferred shares for
  common shares.................     67       182,909         --         --            --           --          182,976
Restricted shares awarded.......      5        18,974         --    (18,079)           --           --              900
Tax benefits related to stock
  and option awards.............     --         2,900         --         --            --           --            2,900
Purchase of treasury stock......     --            --     (2,953)        --            --           --           (2,953)
Amortization of unearned
  compensation..................     --            --         --      3,508            --           --            3,508
Net loss........................     --            --         --         --      (890,671)          --         (890,671)
Dividends ($.10 per share)......     --            --         --         --        (5,476)          --           (5,476)
                                  ------   ----------   --------   --------   -----------      -------       ----------
Balance at December 31, 1997....  1,010     2,359,992        (21)   (16,196)     (795,940)          --        1,548,845
                                  ------   ----------   --------   --------   -----------      -------       ----------
Common stock issued in
  settlement of litigation......     --           342         --         --            --           --              342
Reduction in common stock issued
  for acquisition of Chauvco
  Resources Ltd.................     (4)      (11,094)        --         --            --           --          (11,098)
Exercise of long-term incentive
  plan stock options............     --             3         --         --            --           --                3
Restricted shares awarded.......      2         3,053         --       (493)           --           --            2,562
Tax provision related to stock
  and option awards.............     --        (4,300)        --         --            --           --           (4,300)
Purchase of treasury stock......     --            --    (10,367)        --            --           --          (10,367)
Amortization of unearned
  compensation..................     --            --         --     16,689            --           --           16,689
Net loss........................     --            --         --         --      (746,426)          --         (746,426)
Dividends ($.10 per share)......     --            --         --         --       (10,076)          --          (10,076)
Other comprehensive income
  (loss):
  Currency translation
    adjustment..................     --            --         --         --            --        2,903            2,903
                                  ------   ----------   --------   --------   -----------      -------       ----------
Balance at December 31, 1998....  $1,008   $2,347,996   $(10,388)  $     --   $(1,552,442)     $ 2,903       $  789,077
                                  ======   ==========   ========   ========   ===========      =======       ==========
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                       51
<PAGE>   52
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                 YEAR ENDED DECEMBER 31,
                                                            ----------------------------------
                                                              1998         1997        1996
                                                            ---------   ----------   ---------
<S>                                                         <C>         <C>          <C>
Cash flows from operating activities:
  Net income (loss).......................................  $(746,426)  $ (890,671)  $ 140,248
  Adjustments to reconcile net income (loss) to net cash
     provided by operating activities:
     Depletion, depreciation and amortization.............    337,308      212,435     112,134
     Impairment of oil and gas properties.................    459,519    1,356,390          --
     Exploration expenses, including dry holes............     92,311       63,288      17,262
     Deferred income taxes................................     18,600     (501,300)     57,400
     Gain (loss) on disposition of assets, net............        445       (4,969)    (97,140)
     Loss on early extinguishment of debt, net of tax.....         --       13,408          --
     Other noncash items..................................     66,300       18,886      (1,360)
  Change in operating assets and liabilities, net of
     effects from acquisitions and dispositions:
     Accounts receivable..................................     85,413      (39,774)     (2,674)
     Inventories..........................................      2,714       (5,941)      1,842
     Other current assets.................................         30       (1,913)        (32)
     Accounts payable.....................................    (29,800)      27,138        (656)
     Other current liabilities............................     27,662      (18,768)      3,082
                                                            ---------   ----------   ---------
          Net cash provided by operating activities.......    314,076      228,209     230,106
                                                            ---------   ----------   ---------
Cash flows from investing activities:
  Payment for acquisitions, net of cash acquired..........         --      (15,490)         --
  Proceeds from disposition of wholly-owned subsidiaries,
     net of cash disposed.................................         --           --     183,181
  Proceeds from disposition of assets.....................     21,876      115,735      58,370
  Additions to oil and gas properties.....................   (507,337)    (428,640)   (219,394)
  Other property additions, net...........................    (31,546)     (12,783)     (8,428)
                                                            ---------   ----------   ---------
          Net cash provided by (used in) investing
            activities....................................   (517,007)    (341,178)     13,729
                                                            ---------   ----------   ---------
Cash flows from financing activities:
  Borrowings under long-term debt.........................    947,180      821,148         782
  Principal payments on long-term debt....................   (711,524)    (648,208)   (222,157)
  Payments of other noncurrent liabilities................    (17,091)      (7,740)     (2,642)
  Deferred loan fees/issuance costs.......................     (7,189)      (2,396)        (20)
  Dividends...............................................    (10,076)      (5,476)     (3,550)
  Purchase of treasury stock..............................    (10,367)      (2,953)    (24,671)
  Exercise of long-term incentive plan stock options......         --       11,596       6,904
                                                            ---------   ----------   ---------
          Net cash provided by (used in) financing
            activities....................................    190,933      165,971    (245,354)
                                                            ---------   ----------   ---------
Net increase (decrease) in cash and cash equivalents......    (11,998)      53,002      (1,519)
Effect of exchange rate changes on cash and cash
  equivalents.............................................       (494)          --         290
Cash and cash equivalents, beginning of year..............     71,713       18,711      19,940
                                                            ---------   ----------   ---------
Cash and cash equivalents, end of year....................  $  59,221   $   71,713   $  18,711
                                                            =========   ==========   =========
</TABLE>
 
  The accompanying notes are an integral part of these consolidated financial
                                  statements.
 
                                       52
<PAGE>   53
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE A. ORGANIZATION AND NATURE OF OPERATIONS
 
     Pioneer Natural Resources Company (the "Company") is a Delaware Corporation
whose common stock is listed and traded on the New York Stock Exchange and the
Toronto Stock Exchange. The Company was formed by the merger of Parker & Parsley
Petroleum Company ("Parker & Parsley") and MESA Inc. ("Mesa") on August 7, 1997.
The Company was significantly expanded by the subsequent acquisition of the
Canadian and Argentine oil and gas business of Chauvco Resources Ltd.
("Chauvco"), a publicly traded independent oil and gas company based in Calgary,
Canada, on December 18, 1997. The Company is an oil and gas exploration and
production company with ownership interests in oil and gas properties located
principally in the Mid Continent, Southwestern and onshore and offshore Gulf
Coast regions of the United States and in Argentina, Canada and South Africa.
 
     In accordance with the provisions of Accounting Principles Board Opinion
No. 16, "Business Combinations" ("APB 16"), both the merger with Mesa and the
acquisition of Chauvco have been accounted for as purchases by the Company
(formerly Parker & Parsley). As a result, the historical financial statements
for the Company are those of Parker & Parsley prior to August 1997; for the
period from August 1997 through December 31, 1997, the historical financial
statements for the Company reflect the above described merger of Parker &
Parsley and Mesa; and, as of December 31, 1997, the financial statements for the
Company include the addition of the acquired assets and liabilities of Chauvco.
 
NOTE B. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
     PRINCIPLES OF CONSOLIDATION. The consolidated financial statements include
the accounts of the Company and its majority-owned subsidiaries since their
acquisition or formation and the Company's interest in the affiliated oil and
gas partnerships for which it serves as general partner through certain of its
wholly-owned subsidiaries. Investments in less than majority-owned subsidiaries
where the Company has the ability to exercise significant influence over the
investee's operations are accounted for by the equity method; otherwise, they
are accounted for at cost. The Company proportionately consolidates less than
100 percent-owned oil and gas partnerships in accordance with industry practice.
The Company owns less than a 20 percent interest in the oil and gas partnerships
that it proportionately consolidates. All material intercompany balances and
transactions have been eliminated.
 
     USE OF ESTIMATES IN THE PREPARATION OF FINANCIAL STATEMENTS. Preparation of
the accompanying consolidated financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities, the
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual results could differ from those estimates.
 
     CASH EQUIVALENTS. For purposes of the Consolidated Statements of Cash
Flows, cash and cash equivalents include cash on hand and depository accounts
held by banks.
 
     INVENTORIES. Inventories consist of lease and well equipment which are
carried at the lower of cost or market, on a first-in first-out basis.
 
     OIL AND GAS PROPERTIES. The Company utilizes the successful efforts method
of accounting for its oil and gas properties as promulgated by Statement of
Financial Accounting Standards No. 19, "Financial Accounting and Reporting by
Oil and Gas Producing Companies" ("SFAS 19"). Under this method, all costs
associated with productive wells and nonproductive development wells are
capitalized while nonproductive exploration costs are expensed. The Company
capitalizes interest on expenditures for significant development projects until
such time as operations commence.
 
                                       53
<PAGE>   54
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     Capitalized costs relating to proved properties are depleted using the
unit-of-production method based on proved reserves as estimated by the Company's
engineers. Costs of significant nonproducing properties, wells in the process of
being drilled and development projects are excluded from depletion until such
time as the related project is developed and proved reserves are established or
impairment is determined.
 
     Capitalized costs of individual properties sold or abandoned are charged to
accumulated depletion, depreciation and amortization. Proceeds from sales of
individual properties are credited to property costs. No gain or loss is
recognized until the entire amortization base is sold.
 
     If significant, the Company accrues the estimated future costs to plug and
abandon wells under the unit-of-production method. The charge, if any, is
reflected in the accompanying Consolidated Statements of Operations and
Comprehensive Income (Loss) as abandonment expense while the liability is
reflected in the accompanying Consolidated Balance Sheets as other liabilities.
Plugging and abandonment liabilities assumed in a business combination accounted
for as a purchase are recorded at fair value. At December 31, 1998, and 1997,
the Company has plugging and abandonment liabilities of $44.5 million and $35.9
million, respectively.
 
     Unproved oil and gas properties that are individually significant are
periodically assessed for impairment by comparing their cost to their estimated
value on a project-by-project basis. The estimated value is affected by the
results of exploration activities, commodity price outlooks, planned future
sales or expiration of all or a portion of such projects. If the quantity of
potential reserves determined by such evaluations are not sufficient to fully
recover the cost invested in each project, the Company will recognize a loss at
the time of impairment by providing an impairment allowance. The remaining
unproved oil and gas properties are aggregated and an overall impairment
allowance is provided based on the Company's historical experience.
 
     IMPAIRMENT OF LONG-LIVED ASSETS. In accordance with Statement of Financial
Accounting Standards No. 121, "Accounting for the Impairment of Long-Lived
Assets and for Long-Lived Assets to be Disposed Of" ("SFAS 121"), the Company
reviews its long-lived assets to be held and used, including oil and gas
properties accounted for under the successful efforts method of accounting,
whenever events or circumstances indicate that the carrying value of those
assets may not be recoverable. An impairment loss is indicated if the sum of the
expected future cash flows is less than the carrying amount of the assets. In
this circumstance, the Company recognizes an impairment loss for the amount by
which the carrying amount of the asset exceeds the estimated fair value of the
asset.
 
     NATURAL GAS PROCESSING FACILITIES. Through December 31, 1996, the Company
depreciated its gas processing, gathering and transmission facilities and
equipment on a straight-line basis over the estimated useful lives of the
assets, which ranged from 14 to 21 years. Capitalized costs relating to gas
contracts, representing the right to extract liquids and gas, were amortized on
a plant-by-plant basis using the unit-of-production method over the lives of gas
reserves expected to be processed through the facility, as estimated by the
Company's engineers. Upon disposition of a natural gas processing facility, the
cost and related accumulated depreciation and amortization was eliminated from
the accounts and any gain or loss was included in results of operations.
 
     In 1997, the Company began accounting for its natural gas processing
facilities activities as part of its oil and gas properties for financial
reporting purposes. During 1998 and 1997, all revenues and expenses derived from
third party gas volumes processed through the Company's natural gas processing
facilities are reported as components of oil and gas production costs, and the
capitalized costs of natural gas processing facilities are included in proved
oil and gas properties and depleted using the unit-of-production method.
 
     TREASURY STOCK. Treasury stock purchases are recorded at cost. Upon
reissuance, the cost of treasury shares held is reduced by the average purchase
price per share of the aggregate treasury shares held.
 
                                       54
<PAGE>   55
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     INCOME TAXES. The Company accounts for income taxes in accordance with the
provisions of Statement of Financial Accounting Standards No. 109, "Accounting
for Income Taxes" ("SFAS 109"). Under the asset and liability method of SFAS
109, deferred tax assets and liabilities are recognized for the future tax
consequences attributable to differences between the financial statement
carrying amounts of existing assets and liabilities and their respective tax
basis. Deferred tax assets and liabilities are measured using enacted tax rates
expected to apply to taxable income in the years in which those temporary
differences are expected to be recovered or settled. The effect on deferred tax
assets and liabilities of a change in tax rate is recognized in income in the
period that includes the enactment date. Additionally, in accordance with SFAS
109, the Company assesses the likelihood of whether some portion or all of its
recognized deferred tax assets will not be realized in future operating periods.
If such assessments determine that it is more likely than not that some portion
of deferred tax assets will not ultimately be realized, the Company establishes
a deferred tax asset valuation allowance to reduce the carrying value of its
deferred tax assets. Such allowances are recognized in the Company's
Consolidated Balance Sheets as reductions to deferred tax assets and, during the
operating periods in which the allowances are established, in the accompanying
Consolidated Statements of Operations and Comprehensive Income (Loss) as
components of income tax benefit (provision).
 
     The Company and its eligible subsidiaries file a consolidated U.S. federal
income tax return. Certain subsidiaries that are consolidated for financial
reporting purposes are not eligible to be included in the consolidated U.S.
federal income tax return and separate provisions for income taxes have been
determined for these entities or groups of entities.
 
     INCOME (LOSS) PER SHARE. In accordance with the provisions of Statement of
Financial Accounting Standards No. 128, "Earnings per Share" ("SFAS 128"), basic
net income (loss) per share is computed by dividing income available to common
stockholders by the weighted average number of common shares outstanding for the
period. The computation of diluted net income (loss) per share reflects the
potential dilution that could occur if securities or other contracts to issue
common stock were exercised or converted into common stock or resulted in the
issuance of common stock that then shared in the earnings of the entity. For
1998 and 1997, the computation of diluted net loss per share was antidilutive;
therefore, the amounts reported for basic and diluted net loss per share were
the same. The computation of diluted net income per share for the year ended
December 31, 1996 assumes conversion of the Company's 6 1/4% Cumulative
Guaranteed Monthly Income Convertible Preferred Shares ("Preferred Shares")
which increased the weighted average number of shares outstanding to 42.6
million.
 
     COMPREHENSIVE INCOME (LOSS). In June 1997, the Financial Accounting
Standards Board ("FASB") issued Statement of Financial Accounting Standards No.
130, "Reporting Comprehensive Income" (SFAS 130"). SFAS 130 established
standards for the reporting and display of comprehensive income or loss and its
components in a full set of financial statements. Comprehensive income or loss
is determined as net income or loss plus "other comprehensive income or loss"
items that under generally accepted accounting principles are excluded from net
income or loss. The Company's only item of other comprehensive income or loss
are translation adjustments arising from the translation of the financial
statements of non-United States subsidiary entities, whose functional currency
is not United States dollars, to United States dollars. Accordingly, the
accompanying Consolidated Statements of Operations and Comprehensive Income
(Loss) report and display comprehensive income or loss for each period
presented.
 
     ENVIRONMENTAL. The Company is subject to extensive federal, state, local
and foreign environmental laws and regulations. These laws, which are constantly
changing, regulate the discharge of materials into the environment and may
require the Company to remove or mitigate the environmental effects of the
disposal or release of petroleum or chemical substances at various sites.
Environmental expenditures are expensed or capitalized depending on their future
economic benefit. Expenditures that relate to an existing condition caused by
past operations and that have no future economic benefits are expensed.
Liabilities for expenditures
 
                                       55
<PAGE>   56
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
of a noncapital nature are recorded when environmental assessment and/or
remediation is probable and the costs can be reasonably estimated. Such
liabilities are generally undiscounted unless the timing of cash payments for
the liability are fixed or reliably determinable. The Company believes that the
costs for compliance with current environmental laws and regulations have not
had and will not have a material effect on the Company's financial position or
results of operations.
 
     REVENUE RECOGNITION. The Company uses the entitlements method of accounting
for crude oil and natural gas revenues. Sales proceeds in excess of the
Company's entitlement are included in other liabilities and the Company's share
of sales taken by others is included in other assets in the accompanying
Consolidated Balance Sheets. As of December 31, 1998 and 1997, such entitlement
assets totaled $38.2 million and $49.2 million, respectively. Entitlement
liabilities totaled $20.6 million and $20.2 million at December 31, 1998 and
1997, respectively.
 
     STOCK-BASED COMPENSATION. The Company accounts for employee stock-based
compensation using the intrinsic value method prescribed by Accounting
Principles Board Opinion No. 25, "Accounting for Stock Issued to Employees"
("APB 25"). Accordingly, the Company has only adopted the disclosure provisions
of Statement of Financial Accounting Standards No. 123, "Accounting for
Stock-Based Compensation" ("SFAS 123"). See Note G for the pro forma disclosures
of compensation expense determined under the fair-value provisions of SFAS 123.
 
     HEDGING. The financial instruments that the Company accounts for as hedging
contracts must meet the following criteria: the hedging contract must be an
asset, liability or forecasted transaction that exposes the Company to price,
interest rate or foreign exchange rate risk that is not offset in another asset
or liability, the hedging contract must reduce that price, interest rate or
foreign exchange rate risk, and the instrument must be designated as a hedge at
the inception of the contract and throughout the hedge period. In order to
qualify as a hedge, there must be clear correlation between changes in the fair
value of the financial instrument and the fair value of the hedged asset,
liability or forecasted transaction, such that changes in the market value of
the financial instrument will be offset by the effect of price, interest rate or
foreign exchange rate changes on the exposed items.
 
     Gains or losses realized from financial instruments that qualify as hedges
are deferred as assets or liabilities in the accompanying Consolidated Balance
Sheets until the underlying hedged asset, liability or transaction monetizes,
matures or is otherwise recognized under generally accepted accounting
principles. Hedge gains or losses that are recognized in the accompanying
Consolidated Statements of Operations and Comprehensive Income (Loss) are
classified as components of the commodity prices, interest or foreign exchange
rates that the financial instruments hedge. Derivative financial instruments
that do not qualify as hedges are marked-to-market and recorded as assets or
liabilities in the accompanying Consolidated Balance Sheets. Changes in the fair
values of such instruments are recognized as other income or other expense in
the accompanying Consolidated Statements of Operations and Comprehensive Income
(Loss) during the periods in which their fair values change. See Note J for a
description of the specific types of derivative transactions in which the
Company participates.
 
     FOREIGN CURRENCY TRANSLATION. The financial statements of non-United States
entities, whose functional currency is not United States dollars, are translated
to United States dollars as follows: all assets and liabilities at year-end
exchange rates; revenues, costs and expenses at average exchange rates. Gains
and losses from translating non-United States balances are recorded directly in
stockholders' equity. Foreign currency transaction gains and losses are included
in net income (loss).
 
                                       56
<PAGE>   57
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     A summary of the exchange rates used in the preparation of these
consolidated financial statements appear below:
 
<TABLE>
<CAPTION>
                                                                  DECEMBER 31,
                                                              ---------------------
                                                              1998    1997    1996
                                                              -----   -----   -----
<S>                                                           <C>     <C>     <C>
Canadian Dollar conversion to U.S. Dollar -- Balance
  sheet.....................................................  .6534.. .6997     N/A
Canadian Dollar conversion to U.S. Dollar -- Statement of
  operations................................................  .6740     N/A     N/A
Australian Dollar conversion to U.S. Dollar -- Statement of
  operations................................................    N/A   N/A..   .7562
</TABLE>
 
     RECLASSIFICATIONS. Certain reclassifications have been made to the 1997 and
1996 amounts to conform to the 1998 presentations.
 
NOTE C. DISCLOSURES ABOUT FAIR VALUE OF FINANCIAL INSTRUMENTS
 
     The following table presents the carrying amounts and estimated fair values
of the Company's financial instruments at December 31, 1998 and 1997:
 
<TABLE>
<CAPTION>
                                                        1998                      1997
                                               -----------------------   -----------------------
                                                CARRYING       FAIR       CARRYING       FAIR
                                                 AMOUNT       VALUE        AMOUNT       VALUE
                                               ----------   ----------   ----------   ----------
                                                                (IN THOUSANDS)
<S>                                            <C>          <C>          <C>          <C>
Financial assets:
  Cash and cash equivalents..................  $   59,221   $   59,221   $   71,713   $   71,713
  Investments in a non-affiliated entity.....      12,000       12,000           --           --
Financial liabilities:
  Long-term debt:
     Practicable to estimate fair value:
       Lines of credit and term note.........   1,239,032    1,239,032    1,608,980    1,608,980
       8 7/8% senior notes due 2005..........     150,000      144,108      150,000      170,025
       8 1/4% senior notes due 2007..........     149,414      137,826      149,345      166,950
       6 1/2% senior notes due 2008..........     348,418      284,442           --           --
       7 1/5% senior notes due 2028..........     249,908      177,325           --           --
     Not practicable to estimate fair value:
       Other long term debt..................      38,493           --       41,184           --
  Derivative financial instruments, including
     off balance sheet instruments (see Note
     J):
     Interest rate agreements................         (80)         966        2,100        2,704
     Foreign currency agreements.............     (15,350)     (15,350)      (7,438)      (7,438)
     Commodity price hedges..................         (41)      26,548         (689)      12,061
     BTU swap agreement......................     (15,172)     (15,172)      (6,893)      (6,893)
</TABLE>
 
     CASH AND CASH EQUIVALENTS, ACCOUNTS RECEIVABLE, OTHER CURRENT ASSETS,
ACCOUNTS PAYABLE AND OTHER CURRENT LIABILITIES. The carrying amounts approximate
fair value due to the short maturity of these instruments.
 
     INVESTMENT IN A NON-AFFILIATED ENTITY. At December 31, 1998, the Company
had an equity investment in a closely-held non-affiliated entity. The fair value
of this investment was estimated using quoted market prices.
 
     LONG-TERM DEBT. The carrying amount of borrowings outstanding under the
Company's line of credit (see Note E for definitions and descriptions of each)
approximates fair value because these instruments bear
 
                                       57
<PAGE>   58
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
interest at rates tied to current market rates. The fair values of each of the
senior note issuances were based on quoted market prices for each of these
issues.
 
     It was not practicable to estimate the fair value of certain of the
long-term debt obligations because quoted market prices are not available and
the Company does not have a current borrowing rate which could be used as a
comparable rate for the stated maturities of the obligations.
 
     INTEREST RATE SWAP AGREEMENTS. At December 31, 1998 and 1997, the Company
had outstanding five interest rate swap agreements with an aggregate notional
amount of $150 million and one interest rate cap agreement denominated in
Canadian dollars with a notional amount of $80 million Canadian dollars. In
addition to the agreements above, at December 31, 1997, the Company had
outstanding one interest rate swap agreement with a notional amount of $250
million and one cross-currency interest swap with a notional amount of $60
million. These are more fully described in Note J. The fair values of each of
the open interest rate swap agreements were obtained from quotes by the
respective counterparties and represent the estimated net amount the Company
would receive or pay upon termination of the agreements as of December 31 of
each of the respective years, taking into consideration interest rates at that
time.
 
     FOREIGN CURRENCY AGREEMENTS. At December 31, 1998 and 1997, the Company had
two foreign exchange swap agreements with an aggregate remaining notional amount
of $144 million and $216 million as of December 31, 1998 and 1997, respectively.
These are more fully described in Note J. The fair values of these agreements
were obtained from quotes from the counterparty and represent the amounts that
the Company would have paid upon termination of the agreements at December 31,
of the respective years, based upon the spot and forward foreign currency
exchange rates existing in the market at those times.
 
     COMMODITY PRICE HEDGES. The fair values of commodity price hedges
outstanding at December 31, 1998 and 1997 were obtained from quotes provided by
the individual counterparties for each agreement and represent the amount the
Company would be able to receive or required to pay to liquidate the hedges as
of December 31 of each of the respective years.
 
     BTU SWAP AGREEMENTS. The fair value of the Btu swap agreements outstanding
at December 31, 1998 and 1997 were obtained from quotes provided by the
counterparty to these agreements and represent the amount the Company would have
been required to pay to liquidate the agreements as of December 31, for each of
the respective years, based upon the market price for oil and gas as specified
in the agreements.
 
                                       58
<PAGE>   59
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE D. ACQUISITIONS
 
     During August 1997, Parker & Parsley completed a merger with Mesa that
resulted in the creation of the Company. The transaction was accounted for as a
purchase of Mesa by Parker & Parsley in accordance with APB 16. In December
1997, the Company acquired the Canadian and Argentine oil and gas business of
Chauvco, which was also accounted for as a purchase by the Company. These
transactions were accomplished through the issuance of common stock of the
Company to Mesa and Chauvco shareholders (31,782,263 shares and 24,515,179
shares, respectively). The aggregate purchase consideration for assets acquired
and liabilities assumed from Mesa and Chauvco was $991.0 million and $721.4
million, respectively. The following table represents the allocation of the
total purchase price of Mesa and Chauvco to the acquired assets and liabilities
based upon the fair values assigned to each of the significant assets acquired
and liabilities assumed.
 
<TABLE>
<CAPTION>
                                                              ALLOCATION OF AGGREGATE
                                                               PURCHASE CONSIDERATION
                                                              ------------------------
                                                                 MESA        CHAUVCO
                                                              -----------   ----------
                                                                   (IN THOUSANDS)
<S>                                                           <C>           <C>
Net working capital.........................................  $     4,438   $  (20,191)
Property, plant and equipment...............................    2,530,114    1,125,256
Other assets................................................       40,821       65,922
Long-term debt..............................................   (1,191,038)    (234,709)
Other non-current liabilities, including deferred taxes.....     (393,365)    (214,919)
                                                              -----------   ----------
                                                              $   990,970   $  721,359
                                                              ===========   ==========
Common Stock consideration..................................  $   982,566   $  677,232
Transaction costs...........................................        8,404        7,890
Notes payable...............................................           --       36,237
                                                              -----------   ----------
Aggregate purchase consideration............................  $   990,970   $  721,359
                                                              ===========   ==========
</TABLE>
 
     The liabilities assumed include amounts recorded for litigation and certain
other pre-acquisition contingencies of Mesa and Chauvco.
 
     In December 1997, the Company completed an acquisition of assets in the
East Texas Basin from American Cometra, Inc. ("ACI") and Rockland Pipeline Co.
("Rockland"), both subsidiaries of Electrafina S.A. of Belgium ("America Cometra
Acquisition"). The total consideration paid was approximately $130 million,
consisting of $85 million in cash and 1.6 million shares of the Company's common
stock. The Company acquired ACI's producing wells, acreage, seismic data,
royalties and mineral interests, and Rockland's gathering system pipeline and
gas processing plant in the East Texas Basin.
 
     PRO FORMA RESULTS OF OPERATIONS. The following table reflects the pro forma
results of operations as though the merger with Mesa, the acquisition of
Chauvco, the 1996 sale of certain wholly-owned subsidiaries and the 1996 sale of
certain non-strategic domestic assets occurred on January 1, 1996. The pro forma
results of operations of the America Cometra Acquisition are not presented as
they are not material to the consolidated financial statements of the Company.
 
<TABLE>
<CAPTION>
                                                              YEAR ENDED DECEMBER 31,
                                                              ------------------------
                                                                 1997          1996
                                                              -----------   ----------
                                                               (IN THOUSANDS, EXCEPT
                                                                  PER SHARE DATA)
                                                                    (UNAUDITED)
<S>                                                           <C>           <C>
Revenues....................................................   $ 909,564     $959,208
Income (loss) before extraordinary item.....................   $(931,784)    $ 48,717
Income (loss) per share before extraordinary item...........   $   (9.42)    $    .49
</TABLE>
 
                                       59
<PAGE>   60
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE E. LONG-TERM DEBT
 
     Long-term debt consists of the following:
 
<TABLE>
<CAPTION>
                                                                   DECEMBER 31,
                                                              -----------------------
                                                                 1998         1997
                                                              ----------   ----------
                                                                  (IN THOUSANDS)
<S>                                                           <C>          <C>
Lines of credit and term note...............................  $1,249,984   $1,608,980
8 7/8% senior notes due 2005................................     150,000      150,000
8 1/4% senior notes due 2007 (net of discount)..............     149,414      149,345
6 1/2% senior notes due 2008 (net of discount)..............     348,418           --
7 1/5% senior notes due 2028 (net of discount)..............     249,908           --
Other.......................................................      27,541       41,184
                                                              ----------   ----------
                                                               2,175,265    1,949,509
Less current maturities.....................................     306,521        5,791
                                                              ----------   ----------
                                                              $1,868,744   $1,943,718
                                                              ==========   ==========
</TABLE>
 
     Maturities of long-term debt at December 31, 1998 are as follows (in
thousands):
 
<TABLE>
<S>                                                           <C>
1999........................................................  $306,521
2000........................................................  $     --
2001........................................................  $     --
2002........................................................  $934,349
2003........................................................  $  1,447
Thereafter..................................................  $932,948
</TABLE>
 
     LINES OF CREDIT AND TERM NOTE. On August 7, 1997, the successor to Parker &
Parsley and Mesa Operating Company, Pioneer Natural Resources USA, Inc.
("Pioneer USA") (the "Borrower"), entered into two credit facility agreements
("Credit Facility Agreements") with a syndicate of banks (the "Banks") that
refinanced the credit facilities of Parker & Parsley and Mesa. On December 18,
1997, the Company amended and restated the Credit Facility Agreements to
substitute the Company as the Borrower in place of Pioneer USA. One Credit
Facility Agreement (the "Primary Facility") provides for a $1.075 billion credit
facility. On December 31, 1998, the Company had $993.6 million of outstanding
borrowings under the Primary Facility. The maturity date for the Primary
Facility is August 7, 2002. The second Credit Facility Agreement (the "364-day
Facility") provided for a $300 million credit facility with a current maturity
date of August 5, 1999. On June 29, 1998, the Company and the Banks executed an
amendment that reduced the commitment under the 364-day Facility to $85 million.
At December 31, 1998, the Company did not have any borrowings outstanding on the
364-day Facility. Also, on December 18, 1997, the Company refinanced all of
Chauvco's outstanding debt by establishing a $290 million Canadian credit
facility ("Canadian Facility"). During the fourth quarter of 1998, the
outstanding borrowings under the Canadian Facility converted to a $276.0 million
term loan that matures on December 19, 2003, under which the borrower is Pioneer
Natural Resources Canada Inc., and the Company and certain of its subsidiaries
(not including Pioneer USA) provide guarantees. On December 31, 1998, the
Company had $276.0 million of outstanding term loan borrowings under the
Canadian Facility.
 
     Advances on both Credit Facility Agreements bear interest, at the
Borrower's option, based on (a) the prime rate of NationsBank of Texas, N.A.
("Prime Rate") (7.75 percent at December 31, 1998), (b) a Eurodollar rate
(substantially equal to the London Interbank Offered Rate ("LIBOR")), adjusted
for the reserve requirement as determined by the Board of Governors of the
Federal Reserve System with respect to transactions in Eurocurrency liabilities
("LIBOR Rate"), or (c) a competitive bid rate as quoted by the
 
                                       60
<PAGE>   61
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
lending banks electing to participate pursuant to a request by the Borrower.
Advances that are LIBOR Rate have periodic maturities, at the Borrower's option,
of one, two, three, six, nine or twelve months. Advances that are competitive
bid rate have periodic maturities, at the Borrower's option, of not less than 15
days nor more than 360 days. The interest rates on the LIBOR Rate advances vary,
with the interest rate margin ranging from 18 basis points to 55 basis points,
including commitment utilization fees. The interest rate margin is determined by
a grid based upon the Company's senior unsecured long-term public debt rating.
The Company's obligations are guaranteed by Pioneer USA and certain other United
States subsidiaries, and are secured by a pledge of a portion of the capital
stock of certain non-United States subsidiaries.
 
     The Credit Facility Agreements contain various restrictive covenants and
compliance requirements, which include (a) limits on the incurrence of
additional indebtedness and certain types of liens and (b) restrictions as to
merger, sale or transfer of assets and transactions without the Banks' consent.
 
     On March 19, 1999, the Company and the Banks executed amendments to the
Credit Facilities that provide for a $495 million reduction in the combined loan
commitments under the Credit Facilities by December 31, 1999; an increase in the
maximum interest rate margin on LIBOR Rate advances to 350 basis points,
including facility and leverage fees; provisions, under certain circumstances,
for enhancing the Banks' collateral rights; and, amendment of certain associated
debt covenants, the most restrictive of which being the maintenance of a ratio
of outstanding Company senior debt to earnings before interest, depletion,
depreciation, amortization, income taxes, exploration and abandonment and other
non-cash expenses ("EBITDAX") not to exceed 5.75 to one through September 30,
1999, 4.25 to one through March 31, 2000, and 3.5 to one thereafter.
Additionally, the amendment provisions provide for the consolidation of the
Primary Facility and the Canadian Facility. To satisfy the commitment reduction
provisions of the amended Credit Facilities, the Company intends to reduce its
outstanding borrowings through the use of funds generated by the individual or
combined sources of operating activities, oil and gas property divestitures,
borrowings under subordinated debt agreements or additional issuances of equity.
 
     The Company also executed a $100 million note (the "Term Note"), dated as
of December 22, 1997, payable to NationsBank of Texas, N.A. to fund short-term
working capital needs. At the request of the Company, the Term Note was canceled
on January 20, 1998.
 
     SENIOR NOTES. During 1998, the Company completed the issuance of $350
million of 6 1/2% senior notes due 2008 and $250 million of 7 1/5% senior notes
due 2028 for combined net proceeds of $593 million. The proceeds were used
primarily to repay the Company's bank indebtedness.
 
     At December 31, 1998, the Company has the following four issuances of
senior indebtedness outstanding.
 
     8 7/8% senior notes due 2005. $150 million aggregate principal amount
8 7/8% senior notes dated April 12, 1995, due April 15, 2005. Interest on the
8 7/8% senior notes is payable semi-annually on April 15 and October 15 of each
year.
 
     8 1/4% senior notes due 2007. $150 million aggregate principal amount
8 1/4% senior notes dated August 22, 1995, due August 15, 2007. Interest on the
8 1/4% senior notes is payable semi-annually on February 15 and August 15 of
each year.
 
     6 1/2% senior notes due 2008. $350 million aggregate principal amount
6 1/2% senior notes dated January 13, 1998, due January 15, 2008. Interest on
the 6 1/2% senior notes is payable semi-annually on January 15 and July 15 of
each year.
 
     7 1/5% senior notes due 2028. $250 million aggregate principal amount
7 1/5% senior notes dated January 13, 1998, due July 15, 2028. Interest on the
7 1/5% senior notes is payable semi-annually on January 15 and July 15 of each
year.
 
                                       61
<PAGE>   62
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     The 8 7/8% senior notes due 2005 and the 8 1/4% senior notes due 2007 are
governed by an Indenture between the Company and The Chase Manhattan Bank
(National Association) dated April 12, 1995. The 6 1/2% senior notes due 2008
and the 7 1/5% senior notes due 2028 are governed by an Indenture between the
Company and the Bank of New York dated January 15, 1998. The Company's senior
notes are general unsecured obligations ranking equally in right of payment with
all other senior unsecured indebtedness of the Company and are senior in right
of payment to all existing and future subordinated indebtedness of the Company.
In addition, the Company is a holding company that conducts all its operations
through subsidiaries, and the senior notes issuances are structurally
subordinated to all obligations of its subsidiaries. Pioneer USA has fully and
unconditionally guaranteed the senior note issuances.
 
     TENDER OFFER FOR SENIOR SUBORDINATED NOTES. On December 18, 1997, the
Company completed a cash tender offer for two senior subordinated note issuances
(the "Subordinated Notes") assumed as part of the merger with Mesa. The Company
redeemed approximately 91 percent of the 11 5/8% senior subordinated discount
notes due 2006 and approximately 98 percent of the 10 5/8% senior subordinated
notes due 2006 (the "10 5/8% Notes") for a purchase price of $829.90 and
$1,171.40, respectively, per $1,000 tendered plus any interest accrued on the
10 5/8% Notes (the "Tender Offer"). As a result, the Company paid $574.5 million
for the principal amount tendered on the Subordinated Notes, including related
fees, and $15.7 million of accrued interest on the 10 5/8% Notes. As a result of
the Tender Offer, the Company recognized an extraordinary loss on early
extinguishment of debt of $11.9 million (net of a related tax benefit of $6.4
million) during the fourth quarter of 1997. The Company financed the purchase
price of the Subordinated Notes tendered in the offer with borrowings under its
Credit Facility Agreements.
 
     EXTRAORDINARY ITEM. In addition to the extraordinary loss resulting from
the Tender Offer described above, the accompanying Consolidated Statement of
Operations and Comprehensive Income (Loss) for the year ended December 31, 1997
includes a $1.5 million (net of a related tax benefit of $800 thousand) non-
cash charge for an extraordinary loss on early extinguishment of debt resulting
from the merger of Parker & Parsley and Mesa. This extraordinary loss relates to
capitalized issuance fees associated with Parker & Parsley's previously existing
bank credit facility which was replaced by the new Credit Facility Agreements
for the Company.
 
     INTEREST EXPENSE. The following amounts have been charged to interest
expense for the years ended December 31, 1998, 1997 and 1996:
 
<TABLE>
<CAPTION>
                                                           1998      1997      1996
                                                         --------   -------   -------
                                                                (IN THOUSANDS)
<S>                                                      <C>        <C>       <C>
Cash payments for interest.............................  $135,811   $64,667   $44,405
Cash payments for commitment and agency fees...........        --     1,073       804
Accretion of discounts on loans........................    11,787     7,348       261
Amortization of capitalized loan fees..................     1,142     1,177     1,286
Net change in accruals.................................    15,545     3,285      (601)
                                                         --------   -------   -------
                                                         $164,285   $77,550   $46,155
                                                         ========   =======   =======
</TABLE>
 
     The above amounts include $6 million in 1997 and $12 million in 1996
associated with the Preferred Shares of the Company's wholly-owned finance
subsidiary (see Note I).
 
NOTE F. RELATED PARTY TRANSACTIONS
 
     ACTIVITIES WITH AFFILIATED PARTNERSHIPS. The Company, through its
wholly-owned subsidiaries, has in the past sponsored certain affiliated
partnerships, including 35 public and nine private drilling partnerships and
three public income partnerships, all of which were formed primarily for the
purpose of drilling and
 
                                       62
<PAGE>   63
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
completing wells or acquiring producing properties. In accordance with the terms
of the partnership agreements and the related tax partnership agreements of the
affiliated partnerships, the Company participated in the activities of the
sponsored partnerships on a promoted basis. In 1992, the Company discontinued
sponsoring public and private oil and gas development drilling and income
partnerships.
 
     During each of 1994, 1993 and 1992, the Company formed a Direct Investment
Partnership for the purpose of permitting selected key employees to invest
directly, on an unpromoted basis, in wells that the Company drills. The partners
in the Direct Investment Partnerships formed in 1994, 1993 and 1992 pay and
receive approximately .337 percent, 1.5375 percent and 1.865 percent,
respectively, of the costs and revenues attributable to the Company's interest
in the wells that such Direct Investment Partnership participates. The Company
discontinued the formation of Direct Investment Partnerships in 1995.
 
     The Company, through a wholly-owned subsidiary, serves as operator of
properties in which it and its affiliated partnerships have an interest.
Accordingly, the Company receives producing well overhead, drilling well
overhead and other fees related to the operation of the properties. The
affiliated partnerships also reimburse the Company for their allocated share of
general and administrative charges.
 
     The activities with affiliated partnerships are summarized for the
following related party transactions for the years ended December 31, 1998, 1997
and 1996:
 
<TABLE>
<CAPTION>
                                                              1998     1997     1996
                                                             ------   ------   ------
                                                                  (IN THOUSANDS)
<S>                                                          <C>      <C>      <C>
Receipt of lease operating and supervision charges in
  accordance with standard industry operating agreements...  $9,021   $8,547   $8,484
Reimbursement of general and administrative expenses.......  $  739   $1,476   $1,246
</TABLE>
 
     RETIREMENT PLANS. Effective August 8, 1997, the Compensation Committee of
the Board of Directors approved a deferred compensation retirement plan for the
officers and certain key employees of the Company. Each officer and key employee
is allowed to contribute up to 25 percent of their base salary. The Company will
then provide a matching contribution of 100 percent of the officer's and key
employee's contribution limited to the first 10 percent of the officer's base
salary and eight percent of the key employee's base salary. The Company's
matching contribution vests immediately. A trust fund has been established by
the Company to accumulate the contributions made under this retirement plan.
 
     In December 1998, the Company received notification that an investment fund
group had acquired beneficial ownership of greater than 20 percent of the
Company's Common Stock. Pursuant to the provisions within the Company's deferred
compensation retirement plan, if a third party acquires 20 percent or more of
the Company's Common Stock certain change of control provisions contained within
the plan are triggered. Accordingly, in December 1998, the Compensation
Committee of the Board of Directors determined that a change of control had
occurred, effective September 30, 1998, under the deferred compensation
retirement plan. Consequently, all of the contributions to the deferred
compensation retirement plan from August 1997 to December 15, 1998 were
immediately distributed (December 15, 1998 was the earliest practicable date for
the trust fund, once notified of a change of control, to determine contributions
and investment earnings or losses related thereto for distribution).
 
     During 1996 and prior to August 1997, the officers of Parker & Parsley
participated in a similar deferred compensation retirement plan as noted above.
As part of the merger with Mesa, the plan's change of control provision was
triggered and all funds contributed through August 1997 were immediately vested
and distributed.
 
     CONSULTING FEE. Effective January 1, 1999, the Company entered into an
amended and restated agreement with Rainwater, Inc. for a five year term,
whereby the Company will pay Rainwater, Inc.
 
                                       63
<PAGE>   64
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
$300,000 per year and reimburse Rainwater, Inc. for certain expenses in
consideration for consulting and financial analysis services provided to the
Company by Rainwater, Inc. and its representatives. During 1998, the Company
paid Rainwater, Inc. $400,000 plus expenses for consulting and financial
analysis services under a similar agreement. Richard E. Rainwater, who serves on
the Company's Board of Directors, is the sole shareholder of Rainwater, Inc.
 
NOTE G.  INCENTIVE PLANS
 
LONG-TERM INCENTIVE PLAN
 
     In August 1997, the Company's stockholders approved a new long-term
incentive plan (the "Long-Term Incentive Plan"), which provides for the granting
of incentive awards in the form of stock options, stock appreciation rights,
performance units and restricted stock to directors, officers and employees of
the Company. The Long-Term Incentive Plan provides for the issuance of a maximum
number of shares of Common Stock equal to 10 percent of the total number of
shares of Common Stock equivalents outstanding minus the total number of shares
of Common Stock subject to outstanding awards on the date of calculation under
any stock-based plan for the directors, officers or employees of the Company.
 
     As previously noted in Note F, in December 1998, the Company received
notification that an investment fund group had acquired beneficial ownership of
greater than 20 percent of the Company's Common Stock. Pursuant to the
provisions within the Company's Long-Term Incentive Plan, if a third party
acquires 20 percent or more of the Company's Common Stock, certain change of
control provisions contained within the plan are triggered. In December 1998,
the Compensation Committee of the Board of Directors determined that a change of
control had occurred, effective September 30, 1998, under the Long-Term
Incentive Plan. Consequently, all awards granted under the Long-Term Incentive
Plan since its inception in August 1997 through September 30, 1998 were
immediately vested and any restrictions were canceled. Accordingly, in 1998, the
Company recognized $9.6 million in other expense related to restricted stock
awards that were vested.
 
     The following table summarizes the cumulative stock and option awards
granted, forfeited, exercised, in the case of options, and the lapse of
restrictions, in the case of shares, under the Company's Long-Term Incentive
Plan during 1998 and 1997:
 
<TABLE>
<CAPTION>
                                                  FOR THE YEAR ENDED DECEMBER 31,
                                 ------------------------------------------------------------------
                                               1998                              1997
                                 --------------------------------   -------------------------------
                                  SHARES     OPTIONS      TOTAL     SHARES     OPTIONS      TOTAL
                                 --------   ---------   ---------   -------   ---------   ---------
<S>                              <C>        <C>         <C>         <C>       <C>         <C>
Outstanding, beginning of
  year.........................   476,914   1,716,625   2,193,539        --          --          --
Granted........................   137,086   2,146,553   2,283,639   476,914   1,716,625   2,193,539
Forfeited......................   (12,585)   (923,995)   (936,580)       --          --          --
Options exercised..............        --          --          --        --          --          --
Shares with lapse of
  restrictions.................  (601,415)         --    (601,415)       --          --          --
                                 --------   ---------   ---------   -------   ---------   ---------
Outstanding, end of year.......        --   2,939,183   2,939,183   476,914   1,716,625   2,193,539
                                 ========   =========   =========   =======   =========   =========
</TABLE>
 
                                       64
<PAGE>   65
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     The following table calculates the number of shares or options available
for grant under the Company's Long-Term Incentive Plan as of December 31, 1998
and 1997:
 
<TABLE>
<CAPTION>
                                                                    DECEMBER 31,
                                                              -------------------------
                                                                 1998          1997
                                                              -----------   -----------
<S>                                                           <C>           <C>
Shares outstanding..........................................  100,296,223   101,036,971
Options outstanding.........................................    2,939,183     1,716,625
                                                              -----------   -----------
                                                              103,235,406   102,753,596
                                                              ===========   ===========
Maximum shares/options allowed under the Long-Term Incentive
  Plan......................................................   10,323,541    10,275,360
Less: Outstanding awards under Long-Term Incentive Plan.....   (2,939,183)   (2,193,539)
      Outstanding options under Mesa 1991 stock option
      plan..................................................     (407,284)     (418,478)
      Outstanding options under Mesa 1996 incentive plan....     (422,854)     (510,000)
      Outstanding options under Parker & Parsley long-term
        incentive plan......................................     (810,709)     (896,042)
                                                              -----------   -----------
Shares/options available for future grant...................    5,743,511     6,257,301
                                                              ===========   ===========
</TABLE>
 
RESTRICTED STOCK AWARDS
 
     NON-EMPLOYEE DIRECTORS. Pursuant to the Long-Term Incentive Plan, on the
last business day of the month in which the annual meeting of the stockholders
of the Company is held, each non-employee director will automatically receive an
award of Common Stock equal to 50 percent of the then current annual retainer
fee. This award is made in lieu of an amount of cash equal to 50 percent of the
annual retainer fee. In May 1998 and August 1997, the Company issued an
aggregate 17,306 shares and 5,939 shares, respectively, to non-employee
directors pursuant to this arrangement.
 
     When issued, the shares of common stock awarded pursuant to the Long-Term
Incentive Plan are subject to transfer restrictions that lapse on the first
anniversary of the date of the award. In addition, if a non-employee director's
services as a director of the Company are terminated for any reason before the
next annual meeting of the Company's stockholders, a portion of the shares are
forfeited, with the number of forfeited shares being based on the number of
regularly scheduled meetings of the Board of Directors remaining to be held
before the next annual meeting of the Company's stockholders.
 
     OFFICERS AND KEY EMPLOYEES. The Company, at its sole discretion, may pay
annual bonuses awarded to selected officers and key employees either 100 percent
in cash or partially in cash and partially in the form of restricted stock
awards under the Long-Term Incentive Plan. The Company has established target
bonus levels for each officer and key employee. Based upon Company and
individual performance during the year, each officer or key employee has the
potential to earn more or less than their target bonus level. The bonus awards
are determined in the quarter following the Company's December 31 year-end. Any
restricted stock awarded pursuant to this program will be limited to one-half of
each officer's or key employee's target bonus level, and the remainder of the
officer's or key employee's annual bonus will be paid in cash. The number of
shares of restricted stock that are awarded pursuant to the annual bonus program
is based on the closing sales price of the Company's common stock on the day
immediately preceding the date of the award. Ownership of the restricted stock
awarded vests one year after the date it is issued but is subject to transfer
restrictions that lapse on one-third of the shares on each of the first, second
and third anniversaries of the date of grant. Each recipient of restricted stock
also receives an amount of cash equal to the estimated federal income taxes
payable as a result of the receipt of such award. On February 9, 1998, the
Company awarded an aggregate of 81,300 shares of restricted stock at a price of
$22.375 pursuant to the 1997 annual bonus program. The Company has elected not
to award any restricted stock in conjunction with the 1998 annual bonus program.
 
                                       65
<PAGE>   66
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     During 1998 and 1997, the Company made other Long-Term Incentive Plan
awards of 38,480 and 470,975 shares, respectively, to certain officers and key
employees. The shares awarded are subject to a vesting period and transfer
restrictions.
 
STOCK OPTIONS AWARDS
 
     The Company has a program of awarding semi-annual stock options to its
officers and employees as part of their annual compensation package. This
program provides for semi-annual awards at an exercise price based upon the
closing sales price of the Company's common stock on the day preceding the date
of grant, a three year vesting schedule and a five year exercise period from
each vesting date. The Company granted 2,146,553 and 1,716,625 options under the
Long-Term Incentive Plan during 1998 and 1997, respectively.
 
OTHER STOCK BASED PLANS
 
     Prior to the merger with Mesa, both Parker & Parsley and Mesa had long-term
incentive plans (Parker & Parsley Long-Term Incentive Plan, 1991 Stock Option
Plan of Mesa and the 1996 Incentive Plan of Mesa) in place that allowed Parker &
Parsley and Mesa to grant incentive awards similar to the provisions of the
Long-Term Incentive Plan. Upon consummation of the merger between Parker &
Parsley and Mesa, all awards under these plans were assumed by the Company with
the provision that no additional awards be granted under these plans.
 
     The information presented in the remainder of this footnote represents the
awards granted under the Long-Term Incentive Plan since its approval in August
1997, the awards granted in 1997, and 1996 under the Parker & Parsley Long-Term
Incentive Plan, and the assumption in August 1997 of the outstanding option
awards granted under the 1991 Stock Option Plan of Mesa and the 1996 Incentive
Plan of Mesa.
 
     RESTRICTED STOCK AWARDS. The following table reflects the outstanding
restricted stock awards and activity related thereto for 1998, 1997 and 1996:
 
<TABLE>
<CAPTION>
                                                     FOR THE YEAR ENDED     FOR THE YEAR ENDED     FOR THE YEAR ENDED
                                                     DECEMBER 31, 1998      DECEMBER 31, 1997      DECEMBER 31, 1996
                                                    --------------------   --------------------   --------------------
                                                                WEIGHTED               WEIGHTED               WEIGHTED
                                                     NUMBER     AVERAGE     NUMBER     AVERAGE     NUMBER     AVERAGE
                                                    OF SHARES    PRICE     OF SHARES    PRICE     OF SHARES    PRICE
                                                    ---------   --------   ---------   --------   ---------   --------
<S>                                                 <C>         <C>        <C>         <C>        <C>         <C>
Restricted stock awards:
  Outstanding, beginning of year..................   476,914     $37.88      79,819     $23.35     225,244     $23.90
  Shares granted..................................   137,086     $21.13     506,786     $37.43      35,080     $26.54
  Shares forfeited................................   (12,585)    $35.67          --         --      (1,980)    $25.13
  Lapse of restrictions...........................  (601,415)    $34.11    (109,691)    $25.66    (178,525)    $24.65
                                                    --------               --------               --------
  Outstanding, end of year........................        --         --     476,914     $37.88      79,819     $23.35
                                                    ========               ========               ========
</TABLE>
 
     STOCK OPTION AWARDS. The Company applies APB 25 and related interpretations
in accounting for its stock option awards. Accordingly, no compensation expense
has been recognized for its stock option awards. If compensation expense for the
stock option awards had been determined consistent with SFAS 123, the Company's
net income (loss) and net income (loss) per share would have been adjusted to
the pro forma amounts indicated below:
 
<TABLE>
<CAPTION>
                                                    FOR THE YEAR ENDED DECEMBER 31,
                                                   ----------------------------------
                                                     1998         1997         1996
                                                   ---------    ---------    --------
                                                    (IN THOUSANDS, EXCEPT PER SHARE
                                                                AMOUNTS)
<S>                                                <C>          <C>          <C>
Net income (loss)................................  $(775,349)   $(893,729)   $139,297
Basic net income (loss) per share................  $   (7.75)   $  (17.20)   $   3.90
Diluted net income (loss) per share..............  $   (7.75)   $  (17.20)   $   3.43
</TABLE>
 
                                       66
<PAGE>   67
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     Under SFAS 123, the fair value of each stock option grant is estimated on
the date of grant using the Black-Scholes option pricing model with the
following weighted average assumptions used for grants in 1998, 1997 and 1996:
 
<TABLE>
<CAPTION>
                                                           1998       1997       1996
                                                          -------    -------    -------
<S>                                                       <C>        <C>        <C>
Risk-free interest rate.................................    5.45%      5.72%      6.18%
Expected life...........................................  6 years    7 years    4 years
Expected volatility.....................................      36%        36%        32%
Expected dividend yield.................................     .56%       .30%       .34%
</TABLE>
 
     A summary of the Company's stock option plans as of December 31, 1998, 1997
and 1996, and changes during the years ended on those dates is presented below:
 
<TABLE>
<CAPTION>
                                                 FOR THE YEAR ENDED      FOR THE YEAR ENDED      FOR THE YEAR ENDED
                                                  DECEMBER 31, 1998       DECEMBER 31, 1997       DECEMBER 31, 1996
                                                ---------------------   ---------------------   ---------------------
                                                             WEIGHTED                WEIGHTED                WEIGHTED
                                                  NUMBER     AVERAGE      NUMBER     AVERAGE      NUMBER     AVERAGE
                                                OF OPTIONS    PRICE     OF OPTIONS    PRICE     OF OPTIONS    PRICE
                                                ----------   --------   ----------   --------   ----------   --------
<S>                                             <C>          <C>        <C>          <C>        <C>          <C>
Non-statutory stock options:
  Outstanding, beginning of year..............  3,541,145     $31.63    1,362,629     $24.04    1,230,411     $17.51
    Options granted...........................  2,146,553     $19.22    1,744,704     $34.00      637,300     $29.52
    Options assumed...........................         --         --      928,478     $33.97           --         --
    Options forfeited.........................  (1,106,835)   $35.75       (1,500)    $21.33      (35,000)    $23.81
    Options exercised.........................       (833)    $14.25     (493,166)    $23.45     (470,082)    $14.55
                                                ----------              ---------               ---------
  Outstanding, end of year....................  4,580,030     $24.83    3,541,145     $31.63    1,362,629     $24.04
                                                ==========              =========               =========
  Exercisable at end of year..................  3,937,113     $26.60    1,824,520     $29.37      358,177     $18.79
                                                ==========              =========               =========
Weighted average fair value of options granted
  during the year.............................  $    8.21               $   16.10               $   10.03
                                                ==========              =========               =========
</TABLE>
 
     The following table summarizes information about the Company's stock
options outstanding at December 31, 1998:
 
<TABLE>
<CAPTION>
                                      OPTIONS OUTSTANDING                           OPTIONS EXERCISABLE
                     -----------------------------------------------------   ----------------------------------
                          NUMBER         WEIGHTED AVERAGE      WEIGHTED           NUMBER            WEIGHTED
     RANGE OF         OUTSTANDING AT        REMAINING          AVERAGE        EXERCISABLE AT        AVERAGE
  EXERCISE PRICES    DECEMBER 31, 1998   CONTRACTUAL LIFE   EXERCISE PRICE   DECEMBER 31, 1998   EXERCISE PRICE
  ---------------    -----------------   ----------------   --------------   -----------------   --------------
<S>                  <C>                 <C>                <C>              <C>                 <C>
     $ 6 - 18            1,569,319          5.4 years           $15.62             926,402           $16.75
     $19 - 28            1,209,377          5.4 years           $24.16           1,209,377           $24.16
     $29 - 38            1,485,482          4.3 years           $30.01           1,485,482           $30.01
     $39 - 52              298,638          1.8 years           $46.84             298,638           $46.84
     $80 - 82               17,214          3.1 years           $81.81              17,214           $81.81
                         ---------                                               ---------
                         4,580,030                                               3,937,113
                         =========                                               =========
</TABLE>
 
     In addition to the expense associated with the accelerated vesting of
awards under the Company's Long-Term Incentive Plan that occurred as a result of
the change of control, the Company recognized $3.9 million, $3.3 million and
$1.9 million in general and administrative compensation expense related to its
Incentive Plans during 1998, 1997 and 1996, respectively. Additionally, $3.1
million of the Company's 1998 reorganization costs are compensation expenses
related to its Incentive Plans.
 
                                       67
<PAGE>   68
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE H. COMMITMENTS AND CONTINGENCIES
 
     SEVERANCE AGREEMENTS. The Company has entered into severance agreements
with its parent company officers, subsidiary company officers and certain key
employees. Salaries and bonuses for the Company's officers are set independent
of this agreement by the Compensation Committee for the parent company officers
and the Management Committee for subsidiary company officers and key employees.
These committees can grant increases or reductions to base salary at their
discretion. The current annual salaries for the parent company officers, the
subsidiary company officers and key employees covered under such agreements
total approximately $7.8 million.
 
     Either the Company or the officer/key employee may terminate the officer's
or key employee's employment under the severance agreement at any time. The
Company must pay the officer or key employee an amount equal to one year's base
salary if employment is terminated because of death, disability, or normal
retirement. The Company must pay the officer or key employee an amount equal to
one year's base salary and continue health insurance for the officer or key
employee and his or her immediate family for one year if the Company terminates
employment without cause or if the officer or key employee terminates employment
with good reason, which occurs when reductions in the officer's or key
employee's base annual salary exceed specified limits or if, in the case of
officers, the officer is demoted to an officer position junior to their current
officer position or to a non-officer position. If within one year after a change
in control of the Company, the Company terminates the officer or key employee
without cause or if the officer or key employee terminates employment with good
reason, the Company must pay parent company officers an amount equal to 2.99
times the sum of the officer's base salary plus target bonus for the year and
subsidiary company officers and key employees an amount equal to two times the
officer's or key employee's base salary and continue health insurance for the
officer or key employee and his immediate family for one year. If the officer or
key employee terminates employment with the Company without good reason between
six months and one year after a change in control, or at any time within one
year after a change in control if the officer or key employee is required to
move, then the Company must pay the officer or key employee one year's base
salary and continue health insurance for the officer or key employee and his or
her immediate family for one year. Officers and key employees are also entitled
to additional payments for certain tax liabilities that may apply to severance
payments following a change in control.
 
     INDEMNIFICATIONS. The Company has indemnified its directors and certain of
its officers, employees and agents with respect to claims and damages arising
from acts or omissions taken in such capacity, as well as with respect to
certain litigation.
 
     LEGAL ACTIONS. The Company is party to various legal actions incidental to
its business, including, but not limited to, the proceedings described below.
The majority of these lawsuits primarily involve claims for damages arising from
oil and gas leases and ownership interest disputes. The Company believes that
the ultimate disposition of these legal actions will not have a material adverse
effect on the Company's consolidated financial position, liquidity, capital
resources or future results of operations. The Company will continue to evaluate
its litigation matters on a quarter-by-quarter basis and will adjust the
litigation reserve as appropriate to reflect the then current status of its
litigation.
 
     Masterson. In February 1992, the current lessors of an oil and gas lease
(the "Gas Lease") dated April 30, 1955, between R.B. Masterson et al., as
lessor, and Colorado Interstate Gas Company ("CIG"), as lessee, sued CIG in
Federal District Court in Amarillo, Texas, claiming that CIG had underpaid
royalties due under the Gas Lease. Under the agreements with CIG, the Company,
as successor to Mesa, has an entitlement to gas produced from the Gas Lease. In
August 1992, CIG filed a third-party complaint against the Company for any such
royalty underpayment which may be allocable to the Company. Plaintiffs alleged
that the underpayment was the result of CIG's use of an improper gas sales price
upon which to calculate royalties and that the proper price should have been
determined pursuant to a "favored-nations" clause in a
                                       68
<PAGE>   69
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
July 1, 1967, amendment to the Gas Lease. The plaintiffs also sought a
declaration by the court as to the proper price to be used for calculating
future royalties.
 
     The plaintiffs alleged royalty underpayments of approximately $500 million
(including interest at 10 percent) dating from July 1, 1967. In March 1995, the
court made certain pretrial rulings that eliminated approximately $400 million
of the plaintiff's claims (which related to periods prior to October 1, 1989),
but which also reduced a number of the Company's defenses. The Company and CIG
filed stipulations with the court whereby the Company would have been liable for
between 50 percent and 60 percent, depending on the time period covered, of an
adverse judgment against CIG or post-February 1988 underpayments of royalties.
 
     On March 22, 1995, a jury trial began and on May 4, 1995, the jury returned
its verdict. Among its findings, the jury determined that CIG had underpaid
royalties for the period after September 30, 1989, in the amount of
approximately $140,000. Although the plaintiffs argued that the
"favored-nations" clause entitled them to be paid for all of their gas at the
highest price voluntarily paid by CIG to any other lessor, the jury determined
that the plaintiffs were estopped from claiming that the "favored-nations"
clause provides for other than a pricing-scheme to pricing-scheme comparison. In
light of this determination, and the plaintiff's stipulation that a
pricing-scheme to pricing-scheme comparison would not result in any "trigger
prices" or damages, defendants asked the court for a judgment that plaintiffs
take nothing. The court, on June 7, 1995, entered final judgment that plaintiffs
recover no monetary damages. The plaintiffs filed a motion for new trial on June
22, 1995. The court, on July 18, 1997, denied plaintiffs' motion. The plaintiffs
have appealed to the Fifth Circuit Court of Appeals, where oral arguments were
heard in December 1998 and a decision could be announced by the end of the first
quarter of 1999.
 
     On June 7, 1996, the plaintiffs filed a separate suit against CIG and the
Company in state court in Amarillo, Texas, similarly claiming underpayment of
royalties under the "favored-nations" clause, but based upon the above-described
pricing-scheme to pricing-scheme comparison on a well-by-well monthly basis. The
plaintiffs also claim underpayment of royalties since June 7, 1995, under the
"favored-nations" clause based upon either the pricing-scheme to pricing-scheme
method or their previously alleged higher price method. The Company believes it
has several defenses to this action and intends to contest it vigorously. The
Company has not yet determined the amount of damages, if any, that would be
payable if such action was determined adversely to the Company.
 
     The federal court in the above-referenced first suit issued an order on
July 29, 1996, which stayed the state suit pending the plaintiffs' resolution of
the first suit.
 
     Based on the jury verdict and final judgment, the Company does not
currently expect the ultimate resolution of either of these lawsuits to have a
material adverse effect on its financial position or results of operations.
 
Kansas ad valorem tax.
 
     The Natural Gas Policy Act of 1978 ("NGPA") allows a "severance, production
or similar" tax to be included as an add-on, over and above the maximum lawful
price for natural gas. Based on a Federal Energy Regulatory Commission ("FERC")
ruling that Kansas ad valorem tax was such a tax, Mesa collected the Kansas ad
valorem tax in addition to the otherwise maximum lawful price. The FERC's ruling
was appealed to the United States Court of Appeals for the District of Columbia
("D.C. Circuit"), which held in June 1988 that the FERC failed to provide a
reasoned basis for its findings and remanded the case to the FERC for further
consideration.
 
     On December 1, 1993, the FERC issued an order reversing its prior ruling,
but limiting the effect of its decision to Kansas ad valorem taxes for sales
made on or after June 28, 1988. The FERC clarified the effective date of its
decision by an order dated May 18, 1994. The order clarified that the effective
date applies to tax
                                       69
<PAGE>   70
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
bills rendered after June 28, 1988, not sales made on or after that date.
Numerous parties filed appeals on the FERC's action in the D.C. Circuit. Various
natural gas producers challenged the FERC's orders on two grounds: (1) that the
Kansas ad valorem tax, properly understood, does qualify for reimbursement under
the NGPA; and (2) the FERC's ruling should, in any event, have been applied
prospectively. Other parties challenged the FERC's orders on the grounds that
the FERC's ruling should have been applied retroactively to December 1, 1978,
the date of the enactment of the NGPA and producers should have been required to
pay refunds accordingly.
 
     The D.C. Circuit issued its decision on August 2, 1996, which holds that
producers must make refunds of all Kansas ad valorem tax collected with respect
to production since October 4, 1983 as opposed to June 28, 1988. Petitions for
rehearing were denied on November 6, 1996. Various natural gas producers
subsequently filed a petition for writ of certiori with the United States
Supreme Court seeking to limit the scope of the potential refunds to tax bills
rendered on or after June 28, 1988 (the effective date originally selected by
the FERC). Williams Natural Gas Company filed a cross-petition for certiori
seeking to impose refund liability back to December 1, 1978. Both petitions were
denied on May 12, 1997.
 
     The Company and other producers filed petitions for adjustment with the
FERC on June 24, 1997. The Company is seeking waiver or set-off from FERC with
respect to that portion of the refund associated with (i) non-recoupable
royalties, (ii) non-recoupable Kansas property taxes based, in part, upon the
higher prices collected, and (iii) interest for all periods. On September 10,
1997, FERC denied this request, and on October 10, 1997, the Company and other
producers filed a request for rehearing. Pipelines were given until November 10,
1997 to file claims on refunds sought from producers and refunds totaling
approximately $30 million were made against the Company. The Company is unable
at this time to predict the final outcome of this matter or the amount, if any,
that will ultimately be refunded. As of December 31, 1998, the Company has set
aside $29.7 million, including accrued interest, in an escrow account and has a
corresponding obligation for this litigation recorded in other current
liabilities in the accompanying Consolidated Balance Sheet. In addition, during
1998, the Company paid $1.4 million to a pipeline in settlement of the
pipeline's share of the total initial obligation.
 
     LEASE AGREEMENTS. The Company leases equipment and office facilities under
noncancellable operating leases on which rental expense for the years ended
December 31, 1998, 1997 and 1996 was approximately $8.9 million, $3.7 million
and $2.9 million, respectively. Future minimum lease commitments under
noncancellable operating leases at December 31, 1998 are as follows (in
thousands):
 
<TABLE>
<S>                                                           <C>
1999........................................................  $7,846
2000........................................................  $5,933
2001........................................................  $2,029
2002........................................................  $1,685
2003........................................................  $1,234
Thereafter..................................................  $4,206
</TABLE>
 
NOTE I. PREFERRED STOCK OF SUBSIDIARY
 
     On July 28, 1997, the Company issued 6.7 million shares of common stock in
exchange for the 3,776,400 Preferred Shares outstanding. These Preferred Shares
were originally issued by Parker & Parsley Capital LLC, a wholly-owned finance
subsidiary of the Company, in 1994. During 1997 and 1996, the Company recorded
$6 million and $12 million, respectively, of interest expense associated with
the Preferred Shares.
 
                                       70
<PAGE>   71
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE J. DERIVATIVE FINANCIAL INSTRUMENTS
 
     The Company has only limited involvement with derivative financial
instruments and generally does not use them for trading purposes. They are used
to manage well-defined interest rate and commodity price risks. The Company is
exposed to credit losses in the event of nonperformance by the counterparties to
its interest rate swap agreements and its commodity hedges. The Company
anticipates, however, that such counterparties will be able to fully satisfy
their obligations under the contracts. The Company does not obtain collateral or
other security to support financial instruments subject to credit risk but
monitors the credit standing of the counterparties.
 
     As part of the acquisitions of Mesa and Chauvco, the Company became the
successor to certain derivative financial instruments entered into by Mesa or
Chauvco that do not qualify for hedge accounting treatment. Such instruments
will be marked-to-market at the end of each reporting period during their
respective lives and the effects on the Company's results of operations in
future periods could be significant. Those instruments not qualifying for hedge
accounting are designated under the heading "Mark-to-Market Derivatives" below.
 
HEDGE DERIVATIVES
 
     INTEREST RATE SWAP AGREEMENTS. During the second quarter of 1996, the
Company entered into a series of interest rate swap agreements for an aggregate
amount of $150 million with four counterparties. These agreements, which have a
term of three years, effectively convert a portion of the Company's fixed-rate
borrowings into floating-rate obligations. The weighted average fixed rate being
received by the Company over the term of these agreements is 6.62 percent while
the weighted average variable rate paid by the Company for the years ended
December 31, 1998, 1997 and 1996 was 5.75 percent, 5.78 percent and 5.56
percent, respectively. The variable rate will be redetermined approximately
every six months based upon the London interbank offered rate at that point in
time. The Company was also party to an interest rate swap agreement for an
aggregate amount of $250 million with one counterparty. This agreement, which
expired in August 1998, effectively converted a portion of the Company's
floating-rate borrowings into fixed-rate obligations. The effect of this
agreement was to provide the Company with an interest rate of 6.23 percent on
$250 million in nominal principal amount for the term of the agreement. The
accompanying Consolidated Statements of Operations and Comprehensive Income
(Loss) for the years ended December 31, 1998, 1997 and 1996 include a reduction
in interest expense of $356 thousand, $847 thousand and $787 thousand,
respectively, to account for the settlement of these rate swap agreements.
 
     During 1997, the Company entered into two agreements with a counterparty
that obligated the Company to sell United States Treasury securities at a
designated point in the future. The face amount of the United States Treasury
securities was $300 million at interest rates ranging from 6.05 percent to 6.33
percent. These agreements effectively converted a portion of the Company's
floating-rate borrowings into fixed-rate obligations. In January 1998, the
Company terminated these agreements at a cost of $16.8 million. This amount is
being amortized over the life of the Company's Primary Facility.
 
     COMMODITY HEDGES. The Company utilizes various swap and option contracts to
(i) reduce the effect of the volatility of price changes on the commodities the
Company produces and sells, (ii) support the Company's annual capital budgeting
and expenditure plans and (iii) lock in prices to protect the economics related
to certain capital projects.
 
     Crude oil. All material purchase contracts governing the Company's oil
production have been tied directly or indirectly to NYMEX prices. During the
fourth quarter of 1998, the Company terminated its 1999 crude oil hedge
contracts. As a result, the Company has deferred in other current liabilities in
the accompanying Consolidated Balance Sheet $14.0 million of hedge gains that
will be recognized in 1999 as
 
                                       71
<PAGE>   72
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
additions to crude oil revenue. The recognition of these hedge gains will
increase 1999 crude oil revenue by $3.5 million per calendar quarter.
 
     The Company reports average oil prices per Bbl including the effects of oil
quality, gathering and transportation costs and the net effect of the oil
hedges. The following table sets forth the Company's oil prices, both realized
(excluding hedge results) and reported, and the net effects of settlements of
oil price hedges to revenue:
 
<TABLE>
<CAPTION>
                                                             YEAR ENDED DECEMBER 31,
                                                             ------------------------
                                                              1998     1997     1996
                                                             ------   ------   ------
<S>                                                          <C>      <C>      <C>
Average price reported per Bbl.............................  $13.08   $18.51   $19.96
Average price realized per Bbl.............................  $11.93   $19.09   $21.33
Addition (reduction) to revenue (in millions)..............  $ 24.8   $ (7.9)  $(15.4)
</TABLE>
 
     Natural Gas Liquids. The Company, from time to time, hedges natural gas
liquids based on actual product prices in order to mitigate some of the
volatility associated with NYMEX pricing. At December 31, 1998, the Company had
no outstanding NGL hedge contracts.
 
     During the year ended December 31, 1998, the Company did not enter into any
natural gas liquids hedge contracts. The Company reported and realized an
average natural gas liquids price of $8.90 per Bbl during the year ended
December 31, 1998. During the year ended December 31, 1997, the Company reported
average natural gas liquids prices of $12.59 per Bbl while realizing an average
price for physical sales (excluding hedging results) of $12.61 per Bbl and
recorded a net decrease to natural gas liquids revenue of $77,600.
 
     Natural Gas. The Company employs a policy of hedging a portion of its gas
production based on the index price upon which the gas is actually sold in order
to mitigate the basis risk between NYMEX prices and actual index prices.
 
                                       72
<PAGE>   73
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     The Company was a party to contracts that hedged a portion of its January
1999 gas production. The January hedge contracts expired in December 1998.
Related thereto, the Company has deferred $2.5 million of hedge gains that will
be recognized in January 1999. The following table sets forth the Company's
outstanding gas hedge contracts as of December 31, 1998. Prices included herein
represent the Company's weighted average index price per MMBtu and, as an
additional point of reference, the weighted average price for the portion of the
Company's gas which is hedged based on NYMEX.
 
<TABLE>
<CAPTION>
                                  FIRST        SECOND         THIRD        FOURTH        YEARLY
                                 QUARTER       QUARTER       QUARTER       QUARTER       AVERAGE
                               -----------   -----------   -----------   -----------   -----------
<S>                            <C>           <C>           <C>           <C>           <C>
Daily gas production:
  1999-Swap Contracts*
     Volume (Mcf)............       93,417       163,445       156,800       133,851       137,044
     Index price per MMBtu...        $2.17         $2.20         $2.21         $2.24         $2.21
     NYMEX price per MMBtu...        $2.39         $2.39         $2.39         $2.39         $2.39
  1999-Collar Options**
     Volume (Mcf)............      107,398       163,827       163,827       154,991       147,686
     Index price per MMBtu...  $2.06-$2.61   $2.06-$2.61   $2.06-$2.61   $2.09-$2.65   $2.07-$2.62
  2000-Swap Contracts*
     Volume (Mcf)............       35,000        35,000        35,000        35,000        35,000
     Index price per MMBtu...        $2.35         $2.35         $2.35         $2.35         $2.35
  2000-Collar Options***
     Volume (Mcf)............       93,741        93,741        93,741        91,089        93,074
     Index price per MMBtu...  $2.14-$2.75   $2.14-$2.75   $2.14-$2.75   $2.15-$2.77   $2.14-$2.75
</TABLE>
 
- ---------------
 
  * Certain counterparties to the 1999 and 2000 Swap Contracts have the
    contractual right to extend 35,000 Mcf per day for one additional year at
    prices of $2.40 and $2.41 per MMBtu, respectively.
 
 ** Concurrent with the Company's purchase of certain of the 1999 Collar
    Options, the Company sold 1999 put options to the counterparties for an
    average volume of 114,286 Mcf per day at an average index price of $1.82 per
    MMBtu. Consequently, if the weighted average 1999 index price falls below
    $1.82 per MMBtu, the Company will receive a price for the notional contract
    volumes that exceeds the weighted average index price by approximately $.30
    per MMBtu. 65,000 Mcf per day of the 1999 Collar Options and associated put
    options sold are extendable at the option of the counterparties for a period
    of one year at average per MMBtu prices of $2.18-$2.79 for the collar
    options and $1.88 for the put options.
 
*** Concurrent with the Company's purchase of the 2000 Collar Options, the
    Company sold 2000 put options to the counterparties for an equal volume at
    an average index price of $1.84 per MMBtu. Consequently, if the weighted
    average 2000 index price falls below $1.84 per MMBtu, the Company will
    receive a price for the notional contract volumes that exceeds the weighted
    average index price by approximately $.30 per MMBtu. 75,000 Mcf per day of
    the 2000 Collar Options and associated put options are extendable for one
    year at the option of the counterparties at average per MMBtu prices of
    $2.20-$2.90 for the collar options and $1.90 for the put options.
 
     The Company reports average gas prices per Mcf including the effects of Btu
content, gathering and transportation costs, gas processing and shrinkage and
the net effect of the gas hedges. The following table sets
 
                                       73
<PAGE>   74
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
forth the Company's gas prices, both realized (excluding hedge results) and
reported, and the net effects of settlements of gas price hedges to revenue:
 
<TABLE>
<CAPTION>
                                                               YEAR ENDED DECEMBER 31,
                                                              -------------------------
                                                               1998     1997      1996
                                                              ------   -------   ------
<S>                                                           <C>      <C>       <C>
Average price reported per Mcf..............................  $1.82    $ 2.20    $2.27
Average price realized per Mcf..............................  $1.80    $ 2.41    $2.39
Addition (reduction) to revenue (in millions)...............  $ 3.6    $(21.9)   $(9.0)
</TABLE>
 
MARK-TO-MARKET DERIVATIVES
 
     INTEREST RATE SWAP/CURRENCY SWAP. At December 31, 1997, the Company was
party to a swap agreement with a counterparty in which the Company paid a
fixed-rate of interest in Canadian dollars and received a fixed-rate of interest
in United States dollars. In July 1998, the Company terminated this agreement
and recognized a $3.5 million pre-tax gain associated therewith.
 
     INTEREST RATE CAP. At December 31, 1998 and 1997, the Company was party to
an interest rate cap agreement with a counterparty which caps the Canadian
dollar banker's acceptance rate at 8.00 percent on a notional amount of $80
million Canadian dollars. The agreement was entered into in 1997 and expires in
September 1999. Under the agreement, the Company pays the counterparty a fixed
amount in Canadian dollars on a quarterly basis. The counterparty has no payment
obligation to the Company until such time as the Canadian banker's acceptance
reference rate exceeds 8.00 percent. The effect of this agreement, in periods in
which the reference rate is below 8.00 percent, is to increase the interest rate
on $80 million Canadian dollars of floating-rate debt by 28 basis points.
 
     FOREIGN CURRENCY AGREEMENTS. The Company has a series of forward foreign
exchange swap agreements to exchange Canadian dollars for United States dollars
at future dates for a fixed amount of the first currency. As of December 31,
1998 and 1997, the United States dollar equivalent of foreign currency exchange
swap agreements approximated $144 million and $216 million, respectively. These
contracts originated with the Company's acquisition of Chauvco in December 1997.
As these contracts do not qualify as hedges, the Company recorded a $14.7
million non-cash pre-tax mark-to-market increase to the recognized liabilities
associated with these agreements in 1998. These contracts will continue to be
marked-to-market until they mature at various dates in the fourth quarter of
2000 and the effects on the Company's results of operations in future periods
could be significant.
 
     BTU SWAP AGREEMENTS. During 1996, Mesa entered into BTU swap agreements
covering 13,036 MMBtu per day from January 1, 1997 through December 31, 2004.
Under the terms of these agreements, the Company received a premium of $.52 per
MMBtu over market natural gas prices from January 1, 1997 through December 31,
1998. Additionally, the Company will receive 10 percent of the NYMEX oil price
for the volumes covered for a six-year period beginning January 1, 1999 and
ending December 31, 2004. As these derivative contracts do not qualify as
hedges, the Company recorded non-cash pre-tax mark-to-market increases to the
liabilities recognized for the BTU swap agreements of $5.8 million and $5.2
million in 1998 and 1997, respectively. These contracts will continue to be
marked-to-market at the end of each reporting period during their respective
lives and the effects on the Company's results of operations in future periods
could be significant.
 
NOTE K. SALES TO MAJOR CUSTOMERS
 
     The Company's share of oil and gas production is sold to various
purchasers. The Company is of the opinion that the loss of any one purchaser
would not have an adverse effect on the ability of the Company to sell its oil
and gas production.
 
                                       74
<PAGE>   75
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     The following domestic customers individually accounted for 10 percent or
more of the consolidated oil and gas revenues of the Company during the years
ended December 31, 1998, 1997 or 1996:
 
<TABLE>
<CAPTION>
                                                              PERCENTAGE OF CONSOLIDATED
                                                                 OIL AND GAS REVENUES
                                                              ---------------------------
                          CUSTOMER                            1998       1997       1996
                          --------                            -----      -----      -----
<S>                                                           <C>        <C>        <C>
Williams Energy Services....................................   10         --         --
Genesis Crude Oil, L.P......................................   10         23         28
Mobil Oil Corporation.......................................    7         16         22
Western Gas Resources.......................................    5         10          9
Producers Energy Marketing, L.L.C.(a).......................    3         11          6
</TABLE>
 
- ---------------
 
(a)  Producers Energy Marketing, LLC ("ProEnergy") is a natural gas marketing
     company in which the Company owned a noncontrolling member interest of
     approximately 10 percent during 1997 and 1996. Effective January 1, 1998,
     the Company withdrew as a member of ProEnergy.
 
     At December 31, 1998, the amounts receivable from Williams Energy Services,
Genesis Crude Oil, L.P., Mobil Oil Corporation and Western Gas Resources were
$9.1 million, $3.8 million, $2.8 million and $1.5 million, respectively, which
are included in the caption "Accounts receivable -- oil and gas sales" in the
accompanying Consolidated Balance Sheet.
 
NOTE L. DISPOSITION OF AUSTRALASIAN ASSETS
 
     On March 28, 1996, the Company completed the sale of certain wholly-owned
Australian subsidiaries to Santos Ltd., and on June 20, 1996, the Company
completed the sale of another wholly-owned subsidiary, Bridge Oil Timor Sea,
Inc., to Phillips Petroleum International Investment Company. During the year
ended December 31, 1996, the Company received aggregate consideration of $237.5
million for these combined sales which consisted of $186.6 million of proceeds
for the equity of such entities, $21.8 million for reimbursement of certain
intercompany cash advances, and the assumption of such subsidiaries" net
liabilities, exclusive of oil and gas properties, of $29.1 million. The
accompanying Consolidated Statement of Operations and Comprehensive Income
(Loss) for the year ended December 31, 1996 includes a pre-tax gain of $83.3
million from the disposition of these subsidiaries (net of transaction expenses
of $8.7 million) and an income tax provision of $16 million. The income tax
provision for the year ended December 31, 1996, includes $6.4 million related to
the write-off of certain net operating loss carryforwards which, with the sale
of the income producing assets in the Australian tax jurisdiction, will not be
utilized in the future.
 
NOTE M. IMPAIRMENT OF LONG-LIVED ASSETS
 
     In accordance with SFAS 121, the Company reviews its proved oil and gas
properties for impairment whenever events and circumstances indicate a decline
in the recoverability of the carrying value of the Company's oil and gas
properties. The Company estimates the expected future net cash flows of its oil
and gas properties and compares such estimated future net cash flows to the
respective carrying amounts of the oil and gas properties to determine if the
carrying amounts are likely to be recoverable. For those proved oil and gas
properties for which the carrying amount exceeds the estimated future net cash
flows, an impairment is determined to exist and the Company adjusts the carrying
amount of those proved oil and gas properties to their fair value as determined
by discounting their expected future net cash flows at a discount rate
commensurate with the risks involved in the industry.
 
     Subsequent to the Mesa purchase in August 1997, crude oil prices began to
decline. Based on the decline in the fourth quarter of 1997, the Company
adjusted its outlook for future commodity prices downward and
 
                                       75
<PAGE>   76
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
recognized a $1.4 billion impairment provision in 1997, primarily related to
Mesa properties which were acquired in August 1997.
 
     In 1998 crude oil prices continued to decline. The Company believed the
continued decline would be short-lived, however, after stabilizing somewhat in
the second and third quarters of 1998, crude oil prices fell sharply again in
the fourth quarter of 1998. As a result, the Company now believes it may take
several years for crude oil prices to recover and, accordingly, it again
adjusted its outlook for future commodity prices downward in the fourth quarter
of 1998. This coupled with the Company's assessment of performance issues
related to certain oil and gas properties resulted in an impairment provision of
$312.2 million in 1998.
 
     As discussed above, using the Company's revised outlook for commodity
prices, the Company reassessed its unproved properties on a project-by-project
basis in 1998, and the Company recognized non-cash, pre-tax unproved property
impairment provisions of $147.3 million.
 
     See Note P for disclosure of these impairment charges by geographic
operating segment.
 
NOTE N. REORGANIZATION
 
     During 1998, the Company announced its plans to sell certain non-strategic
oil and gas fields, its intentions to reorganize its operations by combining its
six domestic operating regions, and other cost reduction initiatives intended to
allow Pioneer to better adapt to declining oil and gas commodity price trends.
Specific cost reduction initiatives included the relocation of most of the
Company's administrative services from Midland, Texas to Irving, Texas; the
closings of the Company's regional offices in Oklahoma City, Oklahoma, Corpus
Christi, Texas and Houston, Texas; the termination of 350 employees, including
several officer positions; and, further centralization of the Company's
organization structure. The consolidation of administrative services to Irving
is complete and the Corpus Christi, Texas office is closed. The Company
anticipates the Houston, Texas and Oklahoma City, Oklahoma offices to be closed
in February 1999. The unpaid employee termination costs as of December 31, 1998
relates to employees who were notified of their pending termination prior to
December 31, 1998, but were still employed with the Company as of December 31,
1998. The unpaid office closing amounts primarily relate to remaining lease
commitments on the office buildings in Oklahoma City, Oklahoma, Corpus Christi,
Texas, and Houston, Texas. As a result of the 1998 reorganization initiatives,
the Company has recognized pre-tax reorganization charges of $33.2 million
during 1998.
 
     The following table provides a description of the components of the 1998
reorganization charges and the remaining unpaid portions of the charges as of
December 31, 1998:
 
<TABLE>
<CAPTION>
                                                       TOTAL
                                                      CHARGES   PAYMENTS   UNPAID PORTION
                                                      -------   --------   --------------
                                                                (IN THOUSANDS)
<S>                                                   <C>       <C>        <C>
Employee terminations...............................  $22,525   $17,845        $4,680
Relocation..........................................    6,677     6,677            --
Office closings.....................................    3,873       343         3,530
Other...............................................      124       124            --
                                                      -------   -------        ------
                                                      $33,199   $24,989        $8,210
                                                      =======   =======        ======
</TABLE>
 
                                       76
<PAGE>   77
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
NOTE O. INCOME TAXES
 
     Income tax provision (benefit) and amounts separately allocated were as
follows:
 
<TABLE>
<CAPTION>
                                                           YEAR ENDED DECEMBER 31,
                                                        -----------------------------
                                                         1998       1997       1996
                                                        -------   ---------   -------
                                                               (IN THOUSANDS)
<S>                                                     <C>       <C>         <C>
Income (loss) before extraordinary item...............  $15,600   $(500,300)  $60,100
Extraordinary gain (loss).............................     -- >      (7,200)       --
Stockholders' equity provision (benefit)..............    4,300      (2,900)   (2,200)
Change in cumulative translation adjustment...........   (6,000)         --        --
                                                        -------   ---------   -------
                                                        $13,900   $(510,400)  $57,900
                                                        =======   =========   =======
</TABLE>
 
     Income tax provision (benefit) attributable to income (loss) before
extraordinary item consists of the following:
 
<TABLE>
<CAPTION>
                                                          YEAR ENDED DECEMBER 31,
                                                      -------------------------------
                                                        1998        1997       1996
                                                      ---------   ---------   -------
                                                              (IN THOUSANDS)
<S>                                                   <C>         <C>         <C>
Current:
  U.S. federal......................................  $  (3,300)  $     900   $   300
  State and local...................................        300         100        --
                                                      ---------   ---------   -------
                                                         (3,000)      1,000       300
                                                      ---------   ---------   -------
Deferred:
  U.S. Federal......................................  $ 123,500    (470,000)   51,700
  State and local...................................       (300)    (28,500)       --
  Foreign...........................................   (104,600)     (2,800)    8,100
                                                      ---------   ---------   -------
                                                         18,600    (501,300)   59,800
                                                      ---------   ---------   -------
Total...............................................  $  15,600   $(500,300)  $60,100
                                                      =========   =========   =======
</TABLE>
 
     Income (loss) before income taxes and extraordinary item consists of the
following:
 
<TABLE>
<CAPTION>
                                                         YEAR ENDED DECEMBER 31,
                                                    ----------------------------------
                                                      1998         1997         1996
                                                    ---------   -----------   --------
                                                              (IN THOUSANDS)
<S>                                                 <C>         <C>           <C>
Income (loss) before income taxes and
  extraordinary item:
  U.S. federal....................................  $(393,602)  $(1,369,582)  $121,680
  Foreign.........................................   (337,224)       (7,981)    78,668
                                                    ---------   -----------   --------
                                                    $(730,826)  $(1,377,563)  $200,348
                                                    =========   ===========   ========
</TABLE>
 
                                       77
<PAGE>   78
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     Reconciliations of the U.S. federal statutory tax rate to the Company's
effective tax rate for income (loss) before extraordinary items are as follows:
 
<TABLE>
<CAPTION>
                                                              1998     1997     1996
                                                              -----    -----    ----
                                                                 (IN PERCENTAGES)
<S>                                                           <C>      <C>      <C>
U.S. federal statutory tax rate.............................  (35.0)   (35.0)   35.0
Disposition of foreign subsidiaries.........................     --       --    (6.9)
Valuation allowance.........................................   37.1       --      --
Other.......................................................     --     (1.3)    1.9
                                                              -----    -----    ----
Consolidated effective tax rate.............................    2.1    (36.3)   30.0
                                                              =====    =====    ====
</TABLE>
 
     The tax effects of temporary differences that give rise to significant
portions of the deferred tax assets and deferred tax liabilities were as
follows:
 
<TABLE>
<CAPTION>
                                                                  DECEMBER 31,
                                                              --------------------
                                                                1998        1997
                                                              ---------   --------
                                                                 (IN THOUSANDS)
<S>                                                           <C>         <C>
Deferred tax assets:
  Net operating loss carryforwards..........................  $ 291,678   $184,438
  Alternative minimum tax credit carryforwards..............      1,565      4,903
  Other.....................................................     73,260     57,248
                                                              ---------   --------
          Total deferred tax assets.........................    366,503    246,589
  Valuation allowance.......................................   (271,100)        --
                                                              ---------   --------
          Net deferred tax assets...........................     95,403    246,589
                                                              ---------   --------
Deferred tax liabilities:
  Oil and gas properties, principally due to differences in
     basis and depletion and the deduction of intangible
     drilling costs for tax purposes........................     44,058    206,721
  Other.....................................................     11,645     35,168
                                                              ---------   --------
          Total deferred tax liabilities....................     55,703    241,889
                                                              ---------   --------
          Net deferred tax asset............................  $  39,700   $  4,700
                                                              =========   ========
</TABLE>
 
     Realization of deferred tax assets associated with net operating loss
carryforwards ("NOLs") and other credit carryforwards is dependent upon
generating sufficient taxable income prior to their expiration. The Company
believes that there is a risk, in light of the Company's revised outlook for
future commodity prices as discussed in Note M, that certain of these NOLs and
other credit carryforwards may expire unused and, accordingly, has established a
valuation allowance of $271.1 million in 1998 against them. Although realization
is not assured for the remaining deferred tax asset, the Company believes it is
more likely than not that they will be realized through future taxable earnings
or alternative tax planning strategies. However, the net deferred tax assets
could be reduced further if the Company's estimate of taxable income in future
periods is significantly reduced or alternative tax planning strategies are no
longer viable.
 
     As discussed in Note B, certain subsidiaries that are consolidated for
financial reporting purposes are not eligible to be included in the Company's
consolidated U.S. federal income tax return and separate provisions for income
taxes have been determined for these entities or groups of entities. At December
31, 1998, the Company had NOLs for U.S. federal, Argentine, Canadian, and South
African income tax purposes of $712.6 million, $47.3 million, $52.8 million and
$7.7 million, respectively, which are available to offset future regular taxable
income in each respective tax jurisdiction, if any. Additionally, at December
31, 1998, the
 
                                       78
<PAGE>   79
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
Company has alternative minimum tax net operating loss carryforwards ("AMT
NOLs") in the U.S. of $617.7 million, which are available to reduce future
alternative minimum taxable income, if any. These carryforwards expire as
follows:
 
<TABLE>
<CAPTION>
                                                 U.S.
                                          -------------------   ARGENTINA   CANADA    SOUTH AFRICA
            EXPIRATION DATE                 NOL      AMT NOL       NOL        NOL         NOL
            ---------------               --------   --------   ---------   -------   ------------
                                                               (IN THOUSANDS)
<S>                                       <C>        <C>        <C>         <C>       <C>
December 31, 1999.......................  $     --   $    --     $ 2,161    $    --      $   --
December 31, 2000.......................        --        --       8,788         --          --
December 31, 2001.......................       689       593      10,385         --          --
December 31, 2002.......................     6,066     6,034       6,216         --          --
December 31, 2003.......................       838        --      19,703         --          --
December 31, 2005.......................    11,049    10,762          --     52,767          --
December 31, 2006.......................    30,834    12,254          --         --          --
December 31, 2007.......................   104,107   101,151          --         --          --
December 31, 2008.......................   112,508   106,558          --         --          --
December 31, 2009.......................   129,484   102,727          --         --          --
December 31, 2010.......................   125,111   110,961          --         --          --
December 31, 2011.......................     6,521     4,045          --         --          --
December 31, 2012.......................    68,609    58,890          --         --          --
December 31, 2018.......................   116,823   103,755          --         --          --
Indefinite..............................        --        --          --         --       7,706
                                          --------   --------    -------    -------      ------
     Total..............................  $712,639   $617,730    $47,253    $52,767      $7,706
                                          ========   ========    =======    =======      ======
</TABLE>
 
     The NOLs and AMT NOLs from certain of the U.S. subsidiaries are subject to
various utilization limitations. In total, approximately $36.7 million of the
NOLs and $16.3 million of the AMT NOLs are limited in use to specific U.S.
subsidiaries. Section 382 of the Internal Revenue Code provides another
limitation to $592.1 million of the Company's U.S. NOLs and $503.8 million of
its AMT NOLS. The Company believes the utilization of $352.1 million of the NOLs
and $263.8 million of the AMT NOLs subject to the Section 382 limitation are
limited in each taxable year to approximately $104.2 million and the remaining
$240.0 million of the NOLs and AMT NOLs subject to the Section 382 limitation
are limited in each taxable year to approximately $20.0 million.
 
     The tax returns and the amount of taxable income or loss are subject to
examination by U.S. federal, state and foreign taxing authorities. Current and
estimated tax payments of $300,000, $2.7 million and $970,000 were made in 1998,
1997 and 1996, respectively. In addition, the Company received a refund of $3.3
million in 1998.
 
NOTE P. GEOGRAPHIC OPERATING SEGMENT INFORMATION
 
     In June 1997, the FASB issued Statement of Financial Accounting Standards
No. 131, "Disclosure about Segments of an Enterprise and Related Information"
("SFAS 131"). SFAS 131 establishes guidelines for reporting selected information
about operating segments. The Company has operations in only one industry
segment, that being the oil and gas exploration and production industry;
however, the Company is organizationally structured along geographic operating
segments, or regions. Since the merger with Mesa and the acquisition of Chauvco,
the Company has had reportable operations in the U.S., Argentina and Canada.
During 1997 and 1996, the Company had only minor operations outside the U.S.
 
                                       79
<PAGE>   80
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
     The following table provides the geographic operating segment data required
by SFAS 131, as well as results of operations of oil and gas producing
activities required by Statement of Financial Accounting Standards No. 69,
"Disclosures about Oil and Gas Producing Activities" ("SFAS 69"). Geographic
operating segment income tax benefits (provisions) have been determined based on
statutory rates existing in the various tax jurisdictions where the Company has
oil and gas producing activities. The "Headquarters and other" table column
includes revenues, expenses, additions to properties, plants and equipment, and
assets that are not related to oil and gas producing activities, and that are
not routinely included in the earnings measures or attributes internally
reported to management on a geographic operating segment basis.
 
<TABLE>
<CAPTION>
                                                                                   OTHER     HEADQUARTERS   CONSOLIDATED
                                               U.S.       ARGENTINA    CANADA     FOREIGN     AND OTHER        TOTAL
                                            -----------   ---------   ---------   --------   ------------   ------------
                                                                           (IN THOUSANDS)
<S>                                         <C>           <C>         <C>         <C>        <C>            <C>
YEAR ENDED DECEMBER 31, 1998:
  Oil and gas revenue.....................  $   579,156   $  65,256   $  67,080   $     --    $      --     $   711,492
  Interest and other......................           --          --          --         --       10,452          10,452
  Loss on disposition of assets...........          (52)         --          --         --         (393)           (445)
                                            -----------   ---------   ---------   --------    ---------     -----------
                                                579,104      65,256      67,080         --       10,059         721,499
                                            -----------   ---------   ---------   --------    ---------     -----------
  Production costs........................      177,371      21,158      25,022         --           --         223,551
  Depletion, depreciation and
    amortization..........................      239,561      42,115      40,617         --       15,015         337,308
  Impairment of oil and gas properties....      237,528     136,751      85,240         --           --         459,519
  Exploration and abandonments............       69,263      18,245      20,613     13,737           --         121,858
  General and administrative..............           --          --          --         --       73,000          73,000
  Reorganization..........................           --          --          --         --       33,199          33,199
  Interest................................           --          --          --         --      164,285         164,285
  Other...................................           --          --          --         --       39,605          39,605
                                            -----------   ---------   ---------   --------    ---------     -----------
                                                723,723     218,269     171,492     13,737      325,104       1,452,325
                                            -----------   ---------   ---------   --------    ---------     -----------
  Loss before income taxes................     (144,619)   (153,013)   (104,412)   (13,737)    (315,045)       (730,826)
  Income tax benefit (provision)..........       53,075      50,494      45,628      4,808     (169,605)        (15,600)
                                            -----------   ---------   ---------   --------    ---------     -----------
  Net loss................................  $   (91,544)  $(102,519)  $ (58,784)  $ (8,929)   $(484,650)    $  (746,426)
                                            ===========   =========   =========   ========    =========     ===========
  Additions to properties, plant and
    equipment.............................  $   346,368   $  69,082   $  73,096   $ 18,791    $  31,546     $   538,883
                                            ===========   =========   =========   ========    =========     ===========
  Segment assets..........................  $ 2,259,746   $ 692,271   $ 308,025   $103,702    $ 117,570     $ 3,481,314
                                            ===========   =========   =========   ========    =========     ===========
YEAR ENDED DECEMBER 31, 1997:
  Oil and gas revenue.....................  $   533,865   $   2,917   $      --   $     --    $      --     $   536,782
  Interest and other......................           --          --          --         --        4,278           4,278
  Gain on disposition of assets...........        3,305          --          --         --        1,664           4,969
                                            -----------   ---------   ---------   --------    ---------     -----------
                                                537,170       2,917          --         --        5,942         546,029
                                            -----------   ---------   ---------   --------    ---------     -----------
  Production costs........................      143,332         838          --         --           --         144,170
  Depletion, depreciation and
    amortization..........................      203,160       1,290          --         --        7,985         212,435
  Impairment of oil and gas properties....    1,356,390          --          --         --           --       1,356,390
  Exploration and abandonments............       69,896       1,822          --      5,442           --          77,160
  General and administrative..............           --          --          --         --       48,763          48,763
  Interest................................           --          --          --         --       77,550          77,550
  Other...................................           --          --          --         --        7,124           7,124
                                            -----------   ---------   ---------   --------    ---------     -----------
                                              1,772,778       3,950          --      5,442      141,422       1,923,592
                                            -----------   ---------   ---------   --------    ---------     -----------
  Loss before income taxes and
    extraordinary item....................   (1,235,608)     (1,033)         --     (5,442)    (135,480)     (1,377,563)
  Income tax benefit......................      453,468         341          --      1,905       44,586         500,300
                                            -----------   ---------   ---------   --------    ---------     -----------
  Loss before extraordinary items.........  $  (782,140)  $    (692)  $      --   $ (3,537)   $ (90,894)    $  (877,263)
                                            ===========   =========   =========   ========    =========     ===========
  Additions to properties, plant and
    equipment.............................  $   417,269   $   4,446   $      --   $  6,925    $  12,783     $   441,423
                                            ===========   =========   =========   ========    =========     ===========
  Segment assets..........................  $ 2,684,091   $ 734,569   $ 505,483   $  1,085    $ 227,762     $ 4,152,990
                                            ===========   =========   =========   ========    =========     ===========
</TABLE>
 
                                       80
<PAGE>   81
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
<TABLE>
<CAPTION>
                                                                                   OTHER     HEADQUARTERS   CONSOLIDATED
                                               U.S.       ARGENTINA    CANADA     FOREIGN     AND OTHER        TOTAL
                                            -----------   ---------   ---------   --------   ------------   ------------
                                                                           (IN THOUSANDS)
<S>                                         <C>           <C>         <C>         <C>        <C>            <C>
YEAR ENDED DECEMBER 31, 1996:
  Oil and gas revenue.....................  $   385,198   $   1,142   $      --   $ 10,591    $      --     $   396,931
  Natural gas processing..................           --          --          --         --       23,814          23,814
  Interest and other......................           --          --          --         --       17,458          17,458
  Gain on disposition of assets...........        7,784          --          --     83,262        6,094          97,140
                                            -----------   ---------   ---------   --------    ---------     -----------
                                                392,982       1,142          --     93,853       47,366         535,343
                                            -----------   ---------   ---------   --------    ---------     -----------
  Production costs........................      106,898         136          --      3,300           --         110,334
  Natural gas processing..................           --          --          --         --       12,528          12,528
  Depletion, depreciation and
    amortization..........................       98,655         231          --      3,917        9,331         112,134
  Exploration and abandonments............       16,264       4,008          --      1,435        1,323          23,030
  General and administrative..............           --          --          --         --       28,363          28,363
  Interest................................           --          --          --         --       46,155          46,155
  Other...................................           --          --          --         --        2,451           2,451
                                            -----------   ---------   ---------   --------    ---------     -----------
                                                221,817       4,375          --      8,652      100,151         334,995
                                            -----------   ---------   ---------   --------    ---------     -----------
  Income (loss) before income taxes.......      171,165      (3,233)         --     85,201      (52,785)        200,348
  Income tax benefit (provision)..........      (62,818)      1,067          --    (29,820)      31,471         (60,100)
                                            -----------   ---------   ---------   --------    ---------     -----------
  Net income (loss).......................  $   108,347   $  (2,166)  $      --   $ 55,381    $ (21,314)    $   140,248
                                            ===========   =========   =========   ========    =========     ===========
  Additions to properties, plant and
    equipment.............................  $   207,495   $   4,541   $      --   $  7,358    $   8,428     $   227,822
                                            ===========   =========   =========   ========    =========     ===========
  Segment assets..........................  $ 1,143,282   $   3,543   $       2   $  2,321    $  50,717     $ 1,199,865
                                            ===========   =========   =========   ========    =========     ===========
</TABLE>
 
NOTE Q. EARNINGS PER SHARE
 
     In accordance with the requirements of SFAS 128, the following table
provides a reconciliation between basic and diluted earnings per share for the
year ended December 31, 1996. For 1998 and 1997, the computation of diluted net
loss per share was antidilutive; therefore, the amounts reported for basic and
diluted net loss per share were the same.
 
<TABLE>
<CAPTION>
                                                                              PER SHARE
                                                         INCOME     SHARES     AMOUNT
                                                        --------    ------    ---------
                                                                (IN THOUSANDS)
<S>                                                     <C>         <C>       <C>
Basic EPS
  Income available to common stockholders.............  $140,248    35,475      $3.95
                                                                                =====
Effect of Dilutive Securities
  Options/restricted stock............................        --       394
  Preferred shares....................................     7,683     6,714
                                                        --------    ------
Diluted EPS:
  Income available to common stockholders plus assumed
     conversions......................................  $147,931    42,583      $3.47
                                                        ========    ======      =====
</TABLE>
 
NOTE R. PIONEER USA
 
     Pioneer USA is a wholly-owned subsidiary of the Company that has fully and
unconditionally guaranteed certain debt securities of the Company (see Note E
above). The Company has not prepared financial statements and related
disclosures for Pioneer USA under separate cover because management of the
Company has determined that such information is not material to investors. In
accordance with practices accepted by the U.S. Securities and Exchange
Commission ("SEC"), the Company has prepared Consolidating Financial Statements
in order to quantify the assets of Pioneer USA as a subsidiary guarantor. The
 
                                       81
<PAGE>   82
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
following Consolidating Balance Sheets as of December 31, 1998 and 1997 and
Consolidating Statements of Operations for the Years Ended December 31, 1998 and
1997 present financial information for Pioneer Natural Resources Company as the
Parent on a stand-alone basis (carrying any investments in subsidiaries under
the equity method), financial information for Pioneer USA on a stand-alone basis
(carrying any investment in non-guarantor subsidiaries under the equity method),
financial information for the non-guarantor subsidiaries of the Company on a
consolidated basis, the consolidation and elimination entries necessary to
arrive at the information for the Company on a consolidated basis, and the
financial information for the Company on a consolidated basis. Pioneer USA is
not restricted from making distributions to the Company.
 
     Pioneer USA's guarantees of the Company's debt securities were executed as
a result of the merger with Mesa in August 1997. Consequently, a Consolidating
Statement of Operations for the year ended December 31, 1996 has not been
presented.
 
                                       82
<PAGE>   83
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
                          CONSOLIDATING BALANCE SHEET
                            AS OF DECEMBER 31, 1998
                                 (IN THOUSANDS)
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                           PIONEER
                                           NATURAL
                                          RESOURCES                      NON-
                                           COMPANY       PIONEER      GUARANTOR                        THE
                                          (PARENT)         USA       SUBSIDIARIES   ELIMINATIONS     COMPANY
                                         -----------   -----------   ------------   ------------   -----------
<S>                                      <C>           <C>           <C>            <C>            <C>
Current assets:
  Cash and cash equivalents............  $     3,161   $    37,932    $   18,128    $              $    59,221
  Accounts receivable, trade...........          636        75,236        30,991                       106,863
  Affiliate receivables................    2,240,421    (1,828,672)     (408,092)                        3,657
  Inventories..........................           --         8,930         6,291                        15,221
  Deferred income taxes................        7,100            --            --                         7,100
  Other current assets.................           87         8,868           971                         9,926
                                         -----------   -----------    ----------                   -----------
         Total current assets..........    2,251,405    (1,697,706)     (351,711)                      201,988
                                         -----------   -----------    ----------                   -----------
Property, plant and equipment, at cost:
  Oil and gas properties, using the
    successful efforts method of
    accounting:
    Proved properties..................           --     2,678,637       942,993                     3,621,630
    Unproved properties................           --        58,989       283,600                       342,589
  Accumulated depletion, depreciation
    and amortization...................           --      (753,570)     (176,541)                     (930,111)
                                         -----------   -----------    ----------                   -----------
                                                  --     1,984,056     1,050,052                     3,034,108
                                         -----------   -----------    ----------                   -----------
Deferred income taxes..................       96,800            --            --                        96,800
Other property and equipment, net......           --        38,229        16,781                        55,010
Other assets, net......................        9,787        43,557        40,064                        93,408
Investment in subsidiaries.............      135,204       148,257            --       (283,461)            --
                                         -----------   -----------    ----------                   -----------
                                         $ 2,493,196   $   516,393    $  755,186                   $ 3,481,314
                                         ===========   ===========    ==========                   ===========
 
                                     LIABILITIES AND STOCKHOLDERS' EQUITY
 
Current liabilities:
  Current maturities of long-term
    debt...............................  $   212,302   $     1,189    $   93,030    $              $   306,521
  Accounts payable:
    Trade..............................          697        56,723        37,517                        94,937
    Affiliates.........................           29         4,463            --                         4,492
  Other current liabilities............       21,001        84,759        15,122                       120,882
                                         -----------   -----------    ----------                   -----------
         Total current liabilities.....      234,029       147,134       145,669                       526,832
                                         -----------   -----------    ----------                   -----------
Long-term debt, less current
  maturities...........................    1,676,933           830       190,981                     1,868,744
Other noncurrent liabilities...........           --       189,325        43,136                       232,461
Deferred income taxes..................           --            --        64,200                        64,200
Stockholders' equity:
  Partners' capital....................           --            --            22            (22)            --
  Common stock.........................          934             1            76             (3)         1,008
  Additional paid-in capital...........    2,143,214     2,022,076       589,511     (2,406,805)     2,347,996
  Treasury stock, at cost..............      (10,388)           --            --                       (10,388)
  Retained deficit.....................   (1,551,526)   (1,842,973)     (281,312)     2,123,369     (1,552,442)
  Cumulative translation adjustment....           --            --         2,903                         2,903
                                         -----------   -----------    ----------                   -----------
         Total stockholders' equity....      582,234       179,104       311,200                       789,077
                                         -----------   -----------    ----------                   -----------
Commitments and contingencies..........  $ 2,493,196   $   516,393    $  755,186                   $ 3,481,314
                                         ===========   ===========    ==========                   ===========
</TABLE>
 
                                       83
<PAGE>   84
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
                          CONSOLIDATING BALANCE SHEET
                            AS OF DECEMBER 31, 1997
                                 (IN THOUSANDS)
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                            PIONEER
                                            NATURAL
                                           RESOURCES                      NON-
                                            COMPANY       PIONEER      GUARANTOR                       THE
                                            (PARENT)        USA       SUBSIDIARIES   ELIMINATIONS    COMPANY
                                           ----------   -----------   ------------   ------------   ----------
<S>                                        <C>          <C>           <C>            <C>            <C>
Current assets:
  Cash and cash equivalents..............  $       41   $    49,033    $   22,639     $             $   71,713
  Accounts receivable, trade.............           5       138,569        53,358                      191,932
  Affiliate receivables..................   2,088,082    (1,673,443)     (414,639)                          --
  Inventories............................          --        11,677         1,899                       13,576
  Deferred income taxes..................      16,700            --           200                       16,900
  Other current assets...................          --        10,988         3,079                       14,067
                                           ----------   -----------    ----------                   ----------
         Total current assets............   2,104,828    (1,463,176)     (333,464)                     308,188
                                           ----------   -----------    ----------                   ----------
Property, plant and equipment, at cost:
  Oil and gas properties, using the
    successful efforts method of
    accounting:
    Proved properties....................          --     2,453,750     1,122,221                    3,575,971
    Unproved properties..................          --        98,664       446,410                      545,074
  Accumulated depletion, depreciation and
    amortization.........................          --      (504,628)     (100,575)                    (605,203)
                                           ----------   -----------    ----------                   ----------
                                                   --     2,047,786     1,468,056                    3,515,842
                                           ----------   -----------    ----------                   ----------
Deferred income taxes....................     206,400            --            --                      206,400
Other property and equipment, net........          --        26,096        17,921                       44,017
Other assets, net........................       4,705        68,715        28,098        (22,975)       78,543
Investment in subsidiaries...............     645,113       284,046            --       (929,159)           --
                                           ----------   -----------    ----------                   ----------
                                           $2,961,046   $   963,467    $1,180,611                   $4,152,990
                                           ==========   ===========    ==========                   ==========
 
                                     LIABILITIES AND STOCKHOLDERS' EQUITY
 
Current liabilities:
  Current maturities of long-term debt...  $       --   $       538    $   28,228     $  (22,975)   $    5,791
  Accounts payable:
    Trade................................         663       113,432        62,602                      176,697
    Affiliates...........................          90         9,904            --                        9,994
  Other current liabilities..............       5,771        61,648         1,651                       69,070
                                           ----------   -----------    ----------                   ----------
         Total current liabilities.......       6,524       185,522        92,481                      261,552
                                           ----------   -----------    ----------                   ----------
Long-term debt, less current
  maturities.............................   1,700,500           565       242,653                    1,943,718
Other noncurrent liabilities.............          --       140,668        39,607                      180,275
Deferred income taxes....................      (9,853)           --       228,453                      218,600
Stockholders' equity:
  Partners' capital......................          --            --           401           (401)           --
  Common stock...........................         901             1           110             (2)        1,010
  Additional paid-in capital.............   2,058,935     2,049,072       739,518     (2,487,533)    2,359,992
  Treasury stock, at cost................         (21)           --            --                          (21)
  Unearned compensation..................          --       (16,196)           --                      (16,196)
  Retained deficit.......................    (795,940)   (1,396,165)     (162,612)     1,558,777      (795,940)
                                           ----------   -----------    ----------                   ----------
         Total stockholders' equity......   1,263,875       636,712       577,417                    1,548,845
                                           ----------   -----------    ----------                   ----------
Commitments and contingencies............  $2,961,046   $   963,467    $1,180,611                   $4,152,990
                                           ==========   ===========    ==========                   ==========
</TABLE>
 
                                       84
<PAGE>   85
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
                     CONSOLIDATING STATEMENT OF OPERATIONS
                      FOR THE YEAR ENDED DECEMBER 31, 1998
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                          PIONEER
                                          NATURAL
                                         RESOURCES                   NON-       CONSOLIDATED
                                          COMPANY     PIONEER     GUARANTOR        INCOME                        THE
                                         (PARENT)       USA      SUBSIDIARIES   TAX BENEFIT    ELIMINATIONS    COMPANY
                                         ---------   ---------   ------------   ------------   ------------   ----------
<S>                                      <C>         <C>         <C>            <C>            <C>            <C>
Revenue
  Oil and gas..........................  $     --    $ 523,736    $ 187,756      $              $             $  711,492
  Interest and other...................        38        7,937        2,477                                       10,452
  Loss on disposition of assets, net...        --         (477)          32                                         (445)
                                         ---------   ---------    ---------                                   ----------
                                               38      531,196      190,265                                      721,499
                                         ---------   ---------    ---------                                   ----------
Costs and expenses:
  Oil and gas production...............        --      164,964       58,587                                      223,551
  Depletion, depreciation and
    amortization.......................        --      225,127      112,181                                      337,308
  Impairment of oil and gas
    properties.........................        --      237,529      221,990                                      459,519
  Exploration and abandonments.........        --       71,851       50,007                                      121,858
  General and administrative...........     2,042       57,158       13,800                                       73,000
  Reorganization.......................        --       31,756        1,443                                       33,199
  Interest.............................   (54,237)     159,863       58,659                                      164,285
  Equity loss from subsidiary..........   675,142        4,358           --                      (679,500)            --
  Other................................       722       22,732       16,151                                       39,605
                                         ---------   ---------    ---------                                   ----------
                                          623,669      975,338      532,818                                    1,452,325
                                         ---------   ---------    ---------                                   ----------
Loss before income taxes...............  (623,631)    (444,142)    (342,553)                                    (730,826)
Income tax provision...................        --         (174)     107,369       (122,795)                      (15,600)
                                         ---------   ---------    ---------                                   ----------
    Net loss...........................  $(623,631)  $(444,316)   $(235,184)                                  $ (746,426)
                                         =========   =========    =========                                   ==========
</TABLE>
 
                                       85
<PAGE>   86
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
                     CONSOLIDATING STATEMENT OF OPERATIONS
                      FOR THE YEAR ENDED DECEMBER 31, 1997
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                       PIONEER
                                       NATURAL
                                      RESOURCES                      NON-       CONSOLIDATED
                                       COMPANY       PIONEER      GUARANTOR        INCOME                         THE
                                      (PARENT)         USA       SUBSIDIARIES   TAX BENEFIT    ELIMINATIONS     COMPANY
                                     -----------   -----------   ------------   ------------   ------------   -----------
<S>                                  <C>           <C>           <C>            <C>            <C>            <C>
Revenue
  Oil and gas......................  $        --   $   453,771    $  83,011       $            $              $   536,782
  Interest and other...............           --         5,357          873                         (1,952)         4,278
  Gain on disposition of assets,
    net............................           --         6,062         (402)                          (691)         4,969
                                     -----------   -----------    ---------                                   -----------
                                              --       465,190       83,482                                       546,029
                                     -----------   -----------    ---------                                   -----------
Costs and expenses:
  Oil and gas production...........           --       128,644       15,526                                       144,170
  Depletion, depreciation and
    amortization...................           --       166,495       45,940                                       212,435
  Impairment of oil and gas
    properties.....................           --     1,220,920      135,470                                     1,356,390
  Exploration and abandonments.....           --        67,679        9,481                                        77,160
  General and administrative.......          613        44,766        3,384                                        48,763
  Interest.........................        5,910        67,969        5,623                         (1,952)        77,550
  Equity loss from subsidiary......    1,407,844       124,874           --                     (1,532,718)            --
  Other............................           --         7,065           59                                         7,124
                                     -----------   -----------    ---------                                   -----------
                                       1,414,367     1,828,412      215,483                                     1,923,592
                                     -----------   -----------    ---------                                   -----------
Loss before income taxes and
  extraordinary item...............   (1,414,367)   (1,363,222)    (132,001)                                   (1,377,563)
Income tax benefit.................           --            --           --        500,300                        500,300
                                     -----------   -----------    ---------                                   -----------
Loss before extraordinary item.....   (1,414,367)   (1,363,222)    (132,001)                                     (877,263)
Extraordinary item -- loss on early
  extinguishment of debt net of
  tax..............................           --       (13,408)          --                                       (13,408)
                                     -----------   -----------    ---------                                   -----------
    Net loss.......................  $(1,414,367)  $(1,376,630)   $(132,001)                                  $  (890,671)
                                     ===========   ===========    =========                                   ===========
</TABLE>
 
                                       86
<PAGE>   87
                       PIONEER NATURAL RESOURCES COMPANY
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                        DECEMBER 31, 1998, 1997 AND 1996
 
                     CONSOLIDATING STATEMENT OF CASH FLOWS
                      FOR THE YEAR ENDED DECEMBER 31, 1998
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                            PIONEER
                                            NATURAL
                                           RESOURCES                   NON-       CONSOLIDATED
                                            COMPANY     PIONEER     GUARANTOR      INCOME TAX                      THE
                                           (PARENT)       USA      SUBSIDIARIES    PROVISION     ELIMINATIONS    COMPANY
                                           ---------   ---------   ------------   ------------   ------------   ---------
<S>                                        <C>         <C>         <C>            <C>            <C>            <C>
Cash flows from operating activities:
  Net loss...............................  $(623,631)  $(444,316)   $(235,184)     $(122,795)     $ 679,500     $(746,426)
  Adjustments to reconcile net loss to
    net cash provided by operating
    activities:
    Depletion, depreciation and
      amortization.......................        --      225,127      112,181             --                      337,308
    Impairment of oil and gas
      properties.........................        --      237,529      221,990             --                      459,519
    Exploration expenses, including dry
      holes..............................        --       53,903       38,408             --             --        92,311
    Deferred income taxes................        --          174     (107,369)       125,795                       18,600
    (Gain) loss on disposition of assets,
      net................................        --          477          (32)            --                          445
    Other noncash items..................   685,032       44,181       16,587             --       (679,500)       66,300
Changes in working capital...............  (212,716)     196,284      105,451         (3,000)                      86,019
                                           ---------   ---------    ---------      ---------                    ---------
        Net cash provided by (used in)
          operating activities...........  (151,315)     313,359      152,032             --                      314,076
                                           ---------   ---------    ---------      ---------                    ---------
Cash flows from investing activities:
  Proceeds from disposition of assets....        --       13,791        8,085             --                       21,876
  Additions to oil and gas properties....        --     (309,639)    (197,698)            --                     (507,337)
  Other property additions, net..........        --      (15,862)     (15,684)            --                      (31,546)
                                           ---------   ---------    ---------      ---------                    ---------
        Net cash used in investing
          activities.....................        --     (311,710)    (205,297)            --                     (517,007)
                                           ---------   ---------    ---------      ---------                    ---------
Cash flows from financing activities:
  Borrowings under long-term debt........   886,008           --       61,172             --                      947,180
  Principal payments on long-term debt...  (704,857)      (1,326)      (5,341)            --                     (711,524)
  Payment of noncurrent liabilities......        --      (11,424)      (5,667)            --                      (17,091)
  Dividends..............................    (9,160)          --         (916)            --                      (10,076)
  Purchase of treasury stock.............   (10,367)          --           --             --                      (10,367)
  Deferred loan fees/issuance costs......    (7,189)          --           --             --                       (7,189)
                                           ---------   ---------    ---------      ---------                    ---------
        Net cash provided by (used in)
          financing activities...........   154,435      (12,750)      49,248             --                      190,933
                                           ---------   ---------    ---------      ---------                    ---------
Net increase (decrease) in cash and cash
  equivalents............................     3,120      (11,101)      (4,017)            --                      (11,998)
Effect of exchange rate changes on cash
  and cash equivalents...................        --           --         (494)            --                         (494)
Cash and cash equivalents, beginning of
  period.................................        41       49,033       22,639             --                       71,713
                                           ---------   ---------    ---------      ---------                    ---------
Cash and cash equivalents, end of
  period.................................  $  3,161    $  37,932    $  18,128      $      --                    $  59,221
                                           =========   =========    =========      =========                    =========
</TABLE>
 
                                       87
<PAGE>   88
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
CAPITALIZED COSTS
 
<TABLE>
<CAPTION>
                                                                    DECEMBER 31,
                                                              ------------------------
                                                                 1998          1997
                                                              ----------    ----------
                                                                   (IN THOUSANDS)
<S>                                                           <C>           <C>
Oil and Gas Properties:
  Proved....................................................  $3,621,630    $3,575,971
  Unproved..................................................     342,589       545,074
                                                              ----------    ----------
                                                               3,964,219     4,121,045
  Less accumulated depletion................................    (930,111)     (605,203)
                                                              ----------    ----------
  Net capitalized costs for oil and gas properties..........  $3,034,108    $3,515,842
                                                              ==========    ==========
</TABLE>
 
COSTS INCURRED FOR OIL AND GAS PRODUCING ACTIVITIES
 
<TABLE>
<CAPTION>
                                            PROPERTY
                                        ACQUISITION COST                                     TOTAL
                                    ------------------------   EXPLORATION   DEVELOPMENT     COSTS
                                      PROVED     UNPROVED(a)      COSTS         COSTS       INCURRED
                                    ----------   -----------   -----------   -----------   ----------
                                                             (IN THOUSANDS)
<S>                                 <C>          <C>           <C>           <C>           <C>
Year ended December 31, 1998:
  United States...................  $   19,658    $ 34,092      $ 62,747      $213,943     $  330,440
  Argentina.......................       4,504      67,010        22,521        39,049        133,084
  Canada..........................       1,185     (93,349)       21,871        47,550        (22,743)
  Other foreign(b)................        (136)         --        21,706           412         21,982
                                    ----------    --------      --------      --------     ----------
          Total costs incurred....  $   25,211    $  7,753      $128,845      $300,954     $  462,763
                                    ==========    ========      ========      ========     ==========
Year ended December 31, 1997:
  United States...................  $2,623,993    $ 91,373      $ 88,710      $243,119     $3,047,195
  Argentina.......................     430,607     252,343         1,822         3,927        688,699
  Canada..........................     287,787     194,067            --            --        481,854
  Other foreign(c)................          --         332         5,442            --          5,774
                                    ----------    --------      --------      --------     ----------
          Total costs incurred....  $3,342,387    $538,115      $ 95,974      $247,046     $4,223,522
                                    ==========    ========      ========      ========     ==========
Year ended December 31, 1996:
  United States...................  $   15,699    $  5,255      $ 31,568      $168,553     $  221,075
  Foreign(d)......................          18          --         7,240         4,659         11,917
                                    ----------    --------      --------      --------     ----------
          Total costs incurred....  $   15,717    $  5,255      $ 38,808      $173,212     $  232,992
                                    ==========    ========      ========      ========     ==========
</TABLE>
 
- ---------------
 
(a)  Includes 1998 Chauvco purchase price adjustments of $59.9 million for
     Argentina and $(99.4) million for Canada.
 
(b)  Primarily relates to the drilling of five wells in South Africa.
 
(c)  Primarily relates to an unsuccessful well in Guatemala.
 
(d)  Includes $7.4 million of expenditures related to the Company's Australian
     properties prior to their sale in 1996. The remainder relates to the
     Company's interests in Argentine properties.
 
                                       88
<PAGE>   89
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
RESULTS OF OPERATIONS
 
     Information about the Company's results of operations for oil and gas
producing operations is presented in accordance with SFAS 69 and SFAS 131 in
Note P to the accompanying Notes to Consolidated Financial Statements.
 
RESERVE QUANTITY INFORMATION
 
     The estimates of the Company's proved oil and gas reserves, which are
located principally in the United States, Argentina and Canada are prepared by
the Company's engineers. Reserves were estimated in accordance with guidelines
established by the SEC and the Financial Accounting Standards Board, which
require that reserve estimates be prepared under existing economic and operating
conditions with no provision for price and cost escalations except by
contractual arrangements. The reserve estimates for 1998, 1997 and 1996 utilize
respective oil prices of $10.09, $16.89 and $24.55 per Bbl (reflecting
adjustments for oil quality and gathering and transportation costs), and gas
prices of $1.64, $2.06 and $3.97 per Mcf (reflecting adjustments for BTU
content, gathering and transportation costs and gas processing and shrinkage).
The reserve estimates for 1998 and 1997 utilize respective NGL prices of $6.81
and $12.79 per Bbl.
 
     Oil and gas reserve quantity estimates are subject to numerous
uncertainties inherent in the estimation of quantities of proved reserves and in
the projection of future rates of production and the timing of development
expenditures. The accuracy of such estimates is a function of the quality of
available data and of engineering and geological interpretation and judgment.
Results of subsequent drilling, testing and production may cause either upward
or downward revision of previous estimates. Further, the volumes considered to
be commercially recoverable fluctuate with changes in prices and operating
costs. The Company emphasizes that reserve estimates are inherently imprecise
and that estimates of new discoveries are more imprecise than those of currently
producing oil and gas properties. Accordingly, these estimates are expected to
change as additional information becomes available in the future.
 
                                       89
<PAGE>   90
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
OIL AND GAS PRODUCING ACTIVITIES
 
<TABLE>
<CAPTION>
                                                1998                            1997                            1996
                                   ------------------------------   -----------------------------   ----------------------------
                                     OIL                              OIL                             OIL
                                   & NGLS       GAS                 & NGLS       GAS                & NGLS      GAS
                                   (MBbls)    (MMcf)       MBOE     (MBBls)    (MMcf)      MBOE     (MBbls)    (MMCF)     MBOE
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
<S>                                <C>       <C>         <C>        <C>       <C>         <C>       <C>       <C>        <C>
TOTAL PROVED RESERVES:
UNITED STATES
Balance, January 1...............  329,316   1,719,130    615,838   162,836     828,268   300,881   134,891   778,609    264,659
Revisions of previous
  estimates......................  (34,211)    (32,113)   (39,563)   70,063    (100,755)   53,271    42,614   151,095     67,797
Purchases of minerals in place...       --          --         --   121,286   1,147,921   312,606       300    11,494      2,216
New discoveries and extensions...      183       3,438        756     1,109       7,659     2,385       760    17,607      3,694
Production.......................  (25,327)   (137,741)   (48,284)  (17,737)   (104,868)  (35,215)  (10,872)  (73,924)   (23,193)
Sales of minerals-in-place.......     (323)     (7,070)    (1,501)   (8,241)    (59,095)  (18,090)   (4,857)  (56,613)   (14,292)
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
Balance, December 31.............  269,638   1,545,644    527,246   329,316   1,719,130   615,838   162,836   828,268    300,881
CANADA
Balance, January 1...............   22,796     207,868     57,441        --          --        --        --        --         --
Revisions of previous
  estimates......................   (6,905)     60,247      3,135        --          --        --        --        --         --
Purchases of minerals-in-place...        2          --          2    22,796     207,868    57,441        --        --         --
New discoveries and extensions...      261       5,951      1,253        --          --        --        --        --         --
Production.......................   (3,596)    (19,371)    (6,824)       --          --        --        --        --         --
Sales of minerals-in-place.......     (111)     (5,465)    (1,022)       --          --        --        --        --         --
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
Balance, December 31.............   12,447     249,230     53,985    22,796     207,868    57,441        --        --         --
AUSTRALIA
Balance, January 1...............       --          --         --        --          --        --    12,443   118,297     32,159
Revisions of previous
  estimates......................       --          --         --        --          --        --        --        --         --
Purchases of minerals-in-place...       --          --         --        --          --        --        --        --         --
New discoveries and extensions...       --          --         --        --          --        --        --        --         --
Production.......................       --          --         --        --          --        --      (349)   (1,927)      (669)
Sales of minerals-in-place.......       --          --         --        --          --        --   (12,094)  (116,370)  (31,490)
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
Balance, December 31.............       --          --         --        --          --        --        --        --         --
ARGENTINA
Balance, January 1...............   31,612     340,392     88,344     1,105       1,108     1,290        --        --         --
Revisions of previous
  estimates......................   (7,615)     76,843      5,192      (259)     (1,108)     (444)       --        --         --
Purchases of minerals-in-place...       --          --         --    30,914     340,392    87,646        --        --         --
New discoveries and extensions...    3,522      37,900      9,839        --          --        --     1,159     1,108      1,344
Production.......................   (3,300)    (26,801)    (7,767)     (148)         --      (148)      (54)       --        (54)
Sales of minerals-in-place.......       --          --         --        --          --        --        --        --         --
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
Balance, December 31.............   24,219     428,334     95,608    31,612     340,392    88,344     1,105     1,108      1,290
TOTAL
Balance, January 1...............  383,724   2,267,390    761,623   163,941     829,376   302,171   147,334   896,906    296,818
Revisions of previous
  estimates......................  (48,731)    104,977    (31,236)   69,804    (101,863)   52,827    42,614   151,095     67,797
Purchases of minerals-in-place...        2          --          2   174,996   1,696,181   457,693       300    11,494      2,216
New discoveries and extensions...    3,966      47,289     11,848     1,109       7,659     2,385     1,919    18,715      5,038
Production.......................  (32,223)   (183,913)   (62,875)  (17,885)   (104,868)  (35,363)  (11,275)  (75,851)   (23,916)
Sales of minerals-in-place.......     (434)    (12,535)    (2,523)   (8,241)    (59,095)  (18,090)  (16,951)  (172,983)  (45,782)
                                   -------   ---------   --------   -------   ---------   -------   -------   --------   -------
Balance, December 31.............  306,304   2,223,208    676,839   383,724   2,267,390   761,623   163,941   829,376    302,171
                                   =======   =========   ========   =======   =========   =======   =======   ========   =======
PROVED DEVELOPED RESERVES:
  January 1......................  329,920   1,956,658    656,030   126,370     660,174   236,399   108,920   646,066    216,598
                                   =======   =========   ========   =======   =========   =======   =======   ========   =======
  December 31....................  274,953   2,001,775    608,582   329,920   1,956,658   656,030   126,370   660,174    236,399
                                   =======   =========   ========   =======   =========   =======   =======   ========   =======
</TABLE>
 
                                       90
<PAGE>   91
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS
 
     The standardized measure of discounted future net cash flows is computed by
applying year-end prices of oil and gas (with consideration of price changes
only to the extent provided by contractual arrangements) to the estimated future
production of proved oil and gas reserves less estimated future expenditures
(based on year-end costs) to be incurred in developing and producing the proved
reserves, discounted using a rate of 10% per year to reflect the estimated
timing of the future cash flows. Future income taxes are calculated by comparing
discounted future cash flows to the tax basis of oil and gas properties plus
available carryforwards and credits and applying the current tax rates to the
difference.
 
     Discounted future cash flow estimates like those shown below are not
intended to represent estimates of the fair value of oil and gas properties.
Estimates of fair value should also consider probable reserves, anticipated
future oil and gas prices, interest rates, changes in development and production
costs and risks associated with future production. Because of these and other
considerations, any estimate of fair value is necessarily subjective and
imprecise.
 
                                       91
<PAGE>   92
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
<TABLE>
<CAPTION>
                                                            FOR THE YEAR ENDED DECEMBER 31,
                                                        ---------------------------------------
                                                           1998          1997          1996
                                                        -----------   -----------   -----------
                                                                    (IN THOUSANDS)
<S>                                                     <C>           <C>           <C>
UNITED STATES
Oil and gas producing activities:
  Future cash inflows.................................  $ 5,050,473   $ 8,936,044   $ 7,280,710
  Future production costs.............................   (2,281,406)   (3,185,357)   (2,325,274)
  Future development costs............................     (227,727)     (325,659)     (196,410)
  Future income tax expense...........................           --      (860,632)   (1,385,399)
                                                        -----------   -----------   -----------
                                                          2,541,340     4,564,396     3,373,627
  10% annual discount factor..........................   (1,314,471)   (2,067,371)   (1,574,103)
                                                        -----------   -----------   -----------
  Standardized measure of discounted future net cash
     flows............................................  $ 1,226,869   $ 2,497,025   $ 1,799,524
                                                        ===========   ===========   ===========
ARGENTINA
Oil and gas producing activities:
  Future cash inflows.................................  $   686,911   $   912,688   $    28,211
  Future production costs.............................     (196,446)     (168,105)       (8,099)
  Future development costs............................      (45,710)     (137,060)       (4,456)
  Future income tax expense...........................           --       (60,069)           --
                                                        -----------   -----------   -----------
                                                            444,755       547,454        15,656
  10% annual discount factor..........................     (211,956)     (201,732)       (7,615)
                                                        -----------   -----------   -----------
  Standardized measure of discounted future net cash
     flows............................................  $   232,799   $   345,722   $     8,041
                                                        ===========   ===========   ===========
CANADA
Oil and gas producing activities:
  Future cash inflows.................................  $   526,844   $   662,104   $        --
  Future production costs.............................     (163,414)     (223,325)           --
  Future development costs............................      (49,380)      (48,323)           --
  Future income tax expense...........................      (30,797)      (79,044)           --
                                                        -----------   -----------   -----------
                                                            283,253       311,412            --
  10% annual discount factor..........................      (94,113)     (102,395)           --
                                                        -----------   -----------   -----------
  Standardized measure of discounted future net cash
     flows............................................  $   189,140   $   209,017   $        --
                                                        ===========   ===========   ===========
TOTAL
Oil and gas producing activities:
  Future cash inflows.................................  $ 6,264,228   $10,510,836   $ 7,308,921
  Future production costs.............................   (2,641,266)   (3,576,787)   (2,333,373)
  Future development costs............................     (322,817)     (511,042)     (200,866)
  Future income tax expense...........................      (30,797)     (999,745)   (1,385,399)
                                                        -----------   -----------   -----------
                                                          3,269,348     5,423,262     3,389,283
  10% annual discount factor..........................   (1,620,540)   (2,371,498)   (1,581,718)
                                                        -----------   -----------   -----------
  Standardized measure of discounted future net cash
     flows............................................  $ 1,648,808   $ 3,051,764   $ 1,807,565
                                                        ===========   ===========   ===========
</TABLE>
 
                                       92
<PAGE>   93
 
                       PIONEER NATURAL RESOURCES COMPANY
 
                      UNAUDITED SUPPLEMENTARY INFORMATION
                  YEARS ENDED DECEMBER 31, 1998, 1997 AND 1996
 
OIL AND GAS PRODUCING ACTIVITIES
 
<TABLE>
<CAPTION>
                                                            FOR THE YEAR ENDED DECEMBER 31,
                                                         --------------------------------------
                                                            1998          1997          1996
                                                         -----------   -----------   ----------
                                                                     (IN THOUSANDS)
<S>                                                      <C>           <C>           <C>
Oil and gas sales, net of production costs............   $  (487,942)  $  (392,612)  $ (286,597)
Net changes in prices and production costs............    (1,281,944)   (1,034,678)     866,196
Extensions and discoveries............................        44,018        19,993       53,314
Sales of minerals-in-place............................       (12,748)     (126,879)    (185,859)
Purchases of minerals-in-place........................             3     1,880,570       20,606
Revisions of estimated future development costs.......        (2,777)      (15,158)     (73,587)
Revisions of previous quantity estimates..............       (68,086)      240,375      569,529
Accretion of discount.................................       307,567       234,537      123,174
Changes in production rates, timing and other.........        75,045       (99,753)    (106,896)
                                                         -----------   -----------   ----------
Change in present value of future net reserves........    (1,426,864)      706,395      979,880
Net change in present value of future income taxes....        23,908       537,804     (376,104)
                                                         -----------   -----------   ----------
                                                          (1,402,956)    1,244,199      603,776
Balance, beginning of year............................     3,051,764     1,807,565    1,203,789
                                                         -----------   -----------   ----------
Balance, end of year..................................   $ 1,648,808   $ 3,051,764   $1,807,565
                                                         ===========   ===========   ==========
</TABLE>
 
SELECTED QUARTERLY FINANCIAL RESULTS
 
<TABLE>
<CAPTION>
                                                                     QUARTER
                                                   -------------------------------------------
                                                    FIRST      SECOND     THIRD       FOURTH
                                                   --------   --------   --------   ----------
                                                      (IN THOUSANDS EXCEPT PER SHARE DATA)
<S>                                                <C>        <C>        <C>        <C>
1998
  Operating revenues.............................  $197,369   $183,647   $173,462   $  157,014
  Total revenues.................................  $198,557   $185,107   $178,869   $  158,966
  Costs and expenses.............................  $238,801   $235,616   $247,071   $  730,837
  Net loss.......................................  $(26,844)  $(32,809)  $(43,902)  $ (642,871)
  Net loss per share.............................  $   (.27)  $   (.33)  $   (.44)  $    (6.41)
1997
  Operating revenues.............................  $103,779   $ 94,847   $150,354   $  187,802
  Total revenues.................................  $106,707   $ 97,389   $151,278   $  190,655
  Costs and expenses.............................  $ 77,994   $ 85,576   $168,326   $1,591,696
  Income (loss) before extraordinary item........  $ 18,613   $  7,413   $(11,048)  $ (892,241)
  Net income (loss)..............................  $ 18,613   $  7,413   $(12,566)  $ (904,131)
  Income (loss) before extraordinary item per
     share.......................................  $    .53   $    .21   $   (.18)  $   (11.43)
  Net income (loss) per share....................  $    .53   $    .21   $   (.21)  $   (11.58)
</TABLE>
 
                                       93
<PAGE>   94
 
ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
        FINANCIAL DISCLOSURE
 
     At a meeting held on December 5, 1997, the Board of Directors of the
Company approved the engagement of Ernst & Young LLP as the Company's
independent auditors for the fiscal year ending December 31, 1998 to replace the
firm of KPMG LLP, who were dismissed as auditors of the Company after completing
the audit of the Company for the fiscal year ending December 31, 1997. The audit
committee of the Board of Directors approved the change in auditors on December
5, 1997, subject to ratification by the Company's stockholders.
 
     The reports of KPMG LLP on the Company's financial statements for the past
two fiscal years did not contain an adverse opinion or a disclaimer of opinion
and were not qualified or modified as to uncertainty, audit scope, or accounting
principles.
 
     In connection with the audits of the Company's financial statements for
each of the two fiscal years ended December 31, 1997 and 1996, there were no
disagreements with KPMG LLP on any matters of accounting principles or
practices, financial statement disclosure, or auditing scope and procedures
which, if not resolved to the satisfaction of KPMG LLP would have caused KPMG
LLP to make reference to the matter in their report.
 
     The Company received from KPMG LLP a letter addressed to the Securities and
Exchange Commission stating that KPMG LLP agrees with the above statements. A
copy of the letter was included as Exhibit 16.1 to the Company's annual report
on Form 10-K for the fiscal year ended December 31, 1997.
 
                                    PART III
 
ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT
 
     Set forth below are the names, ages, and positions of the Company's
directors and executive officers as of February 26, 1999.
 
<TABLE>
<CAPTION>
NAME                                      AGE                         POSITION
- ----                                      ---                         --------
<S>                                       <C>   <C>   <C>
I. Jon Brumley..........................  60          Chairman of the Board of Directors and
                                                        Director
Scott D. Sheffield......................  46          President, Chief Executive Officer and
                                                        Director
Timothy L. Dove.........................  42          Executive Vice President -- Business
                                                        Development
Dennis E. Fagerstone....................  50          Executive Vice President
Lon C. Kile.............................  43          Executive Vice President
M. Garrett Smith........................  37          Executive Vice President and Chief
                                                      Financial Officer
Mark L. Withrow.........................  51          Executive Vice President, General
                                                      Counsel and Secretary
James R. Baroffio.......................  67          Director
R. Hartwell Gardner.....................  64          Director
Kenneth A. Hersh........................  36          Director
James L. Houghton.......................  68          Director
Jerry P. Jones..........................  67          Director
Richard E. Rainwater....................  54          Director
Charles E. Ramsey, Jr...................  62          Director
</TABLE>
 
                                       94
<PAGE>   95
 
<TABLE>
<CAPTION>
NAME                                      AGE                         POSITION
- ----                                      ---                         --------
<S>                                       <C>   <C>   <C>
Philip B. Smith.........................  47          Director
Robert L. Stillwell.....................  62          Director
</TABLE>
 
     The Company has classified its Board of Directors into three classes.
Directors in each class are elected to serve for three-year terms and until
their successors are elected and qualified. Each year, the directors of one
class stand for re-election as their terms of office expire. Messrs. Baroffio,
Hersh, Sheffield and Stillwell are designated as Class II directors, and their
terms of office expire at the Annual Meeting. Messrs. Gardner, Houghton and
Philip Smith are designated as Class I directors, and their terms of office
expire at the annual meeting of stockholders in 2001. Messrs. Brumley, Jones,
Rainwater and Ramsey are designated as Class III directors, and their terms of
office expire at the annual meeting of stockholders in 2000. Effective March 18,
1999, Mr. Jones resigned as a Class II director and was re-appointed as a Class
III director. Since the last annual meeting of stockholders, three directors of
the Company, T. Boone Pickens, Arthur L. Smith and Guy J. Turcotte, voluntarily
resigned as directors of the Company. None of such resignations was the result
of a disagreement with the Company on any matter relating to the Company's
operations, policies or practices.
 
     Members of the current Board of Directors (other than Mr. Baroffio) were
appointed under the terms of the merger agreement between Parker & Parsley and
Mesa. Mr. Baroffio became a director in December 1997 under the terms of the
combination agreement between the Company and Chauvco.
 
     Executive officers serve at the discretion of the Board of Directors.
 
     Set forth below is biographical information about each of the Company's
directors and executive officers.
 
     I. Jon Brumley. Mr. Brumley, a graduate of the University of Texas with a
B.A. and of the Wharton School of Finance and Commerce with an M.B.A., has
served as Chairman of the Board of Directors of the Company since August 1997.
Mr. Brumley was also an employee of the Company from August 1997 until May 1998.
Mr. Brumley currently serves as Chairman of the Board of Directors of Encore
Acquisition Partners Inc., an independent oil and gas company that he founded in
April 1998. Mr. Brumley served as Chairman of the Board of Directors and Chief
Executive Officer of Mesa from August 1996 until August 1997. He also co-founded
Cross Timbers Oil Company and served as its Chairman of the Board from 1986 to
mid-1996. Mr. Brumley served as President and Chief Executive Officer of
Southland Royalty Company from 1974 until 1985.
 
     Scott D. Sheffield. Mr. Sheffield, a graduate of the University of Texas
with a Bachelor of Science degree in Petroleum Engineering, has been the
President and Chief Executive Officer of the Company since August 1997. He was
the President and a director of Parker & Parsley since May 1990 and was the
Chairman of the Board and Chief Executive Officer of Parker & Parsley since
October 1990. Mr. Sheffield was the sole director of Parker & Parsley from May
1990 until October 1990. Mr. Sheffield joined Parker & Parsley Development
Company ("PPDC"), a predecessor of Parker & Parsley, as a petroleum engineer in
1979. Mr. Sheffield served as Vice President -- Engineering of PPDC from
September 1981 until April 1985, when he was elected President and a director.
In March 1989, Mr. Sheffield was elected Chairman of the Board and Chief
Executive Officer of PPDC. Before joining PPDC's predecessor, Mr. Sheffield was
employed as a production and reservoir engineer for Amoco Production Company.
 
     Timothy L. Dove. Mr. Dove became Executive Vice President -- Business
Development of the Company in August 1997. Mr. Dove joined Parker & Parsley in
May 1994 as Vice President -- International and was promoted to Senior Vice
President -- Business Development in October 1996, in which position he served
until August 1997. Before joining Parker & Parsley, Mr. Dove was employed with
Diamond Shamrock Corp., and its successor, Maxus Energy Corp, in various
capacities in international exploration and production, marketing, refining, and
planning and development. Mr. Dove earned a Bachelor of Science degree in
Mechanical Engineering from Massachusetts Institute of Technology in 1979 and
received his M.B.A. in 1981 from the University of Chicago.
 
     Dennis E. Fagerstone. Mr. Fagerstone, a graduate of the Colorado School of
Mines with a B.S. in Petroleum Engineering, became an Executive Vice President
of the Company in August 1997. Mr. Fagerstone
 
                                       95
<PAGE>   96
 
served as Executive Vice President and Chief Operating Officer of Mesa from
March 1997, until August 1997. Mr. Fagerstone served as Senior Vice President
and Chief Operating Officer of Mesa from October 1996 to February 1997, and
served as Vice President -- Exploration and Production of Mesa from May 1991 to
October 1996. Mr. Fagerstone served as Vice President -- Operations of Mesa from
June 1988 until May 1991.
 
     Lon C. Kile. Mr. Kile, a graduate of Oklahoma State University with a
Bachelor of Business Administration degree in Accounting, became Executive Vice
President of the Company in August 1997. Mr. Kile joined Parker & Parsley in
1985 and was promoted to Senior Vice President -- Investor Relations in October
1996. Previously, he was Vice President and Manager of the Mid-Continent
Division. Prior to that he held the positions of Vice President -- Equity
Finance & Analysis and Vice President -- Marketing and Program Administration.
Before joining Parker & Parsley, he was employed as Supervisor -- Senior, Audit,
in charge of Parker & Parsley's audit, with Arthur & Young.
 
     M. Garrett Smith. Mr. Smith, a graduate of the University of Texas with a
Bachelor of Science degree in Electrical Engineering and Southern Methodist
University with an M.B.A., became Executive Vice President and Chief Financial
Officer of the Company in December 1997. Prior to that he was Senior Vice
President -- Finance of the Company since August 1997. Mr. Smith served as Vice
President -- Corporate Acquisitions of Mesa from January 1997 until August 1997.
From October 1996 to December 1996, Mr. Smith served as Vice President
 -- Finance of Mesa and from 1994 to 1996, he served as Director of Financial
Planning of Mesa. Mr. Smith was employed by BTC Partners, Inc. (a former
financial advisor to Mesa) from 1989 to 1994.
 
     Mark L. Withrow. Mr. Withrow, a graduate of Abilene Christian University
with a Bachelor of Science degree in Accounting and Texas Tech University with a
Juris Doctorate degree, has been the Executive Vice President, General Counsel
and Secretary of the Company since August 1997. He served as Vice President --
General Counsel of Parker & Parsley from February 1991 until January 1995, and
served as Senior Vice President, General Counsel of Parker & Parsley from
January 1995 until August 1997. He was Parker & Parsley's Secretary from August
1992 until August 1997. Mr. Withrow joined PPDC in January 1991. Before joining
PPDC, Mr. Withrow was the managing partner of the law firm of Turpin, Smith,
Dyer, Saxe & MacDonald, Midland, Texas.
 
     James R. Baroffio. Dr. Baroffio received a B.A. in Geology at the College
of Wooster, Ohio, an M.S. in Geology at Ohio State University, and a Ph.D. in
Geology at the University of Illinois. Before becoming a director of the Company
in December 1997, Dr. Baroffio enjoyed a long career with Standard Oil Company
of California, the predecessor of Chevron Corporation, eventually retiring as
President of Chevron Canada Resources in 1994. Dr. Baroffio was President-elect
of the Colorado Petroleum Association, a member of the Board of Directors of the
Rocky Mountain Oil & Gas Association, and Chairman of the U.S. National
Committee of the World Petroleum Congress. His community leadership positions
included membership on the Board of Directors of Glenbow Museum and the Nature
Conservancy of Canada, as well as serving as President of the Alberta Nature
Conservancy.
 
     R. Hartwell Gardner. Mr. Gardner became a director of the Company in August
1997. He served as a director of Parker & Parsley from November 1995 until
August 1997. Mr. Gardner graduated from Colgate University with a Bachelor of
Arts degree in Economics and then earned an M.B.A. from Harvard University.
Until October 1, 1995, Mr. Gardner was the Treasurer of Mobil Oil Corporation
and Mobil Corporation from 1974 and 1976, respectively. Mr. Gardner is a member
of the Financial Executives Institute of which he served as Chairman in
1986/1987 and is a Director of Oil Investment Corporation Ltd. and Oil Casualty
Investment Corporation Ltd., Pembroke, Bermuda.
 
     Kenneth A. Hersh. Mr. Hersh, who became a director of the Company in August
1997, has been a Managing Director of Natural Gas Partners ("NGP") since 1989.
NGP is a family of investment funds organized to make equity investments in oil
and gas companies. Previously, he was employed by the investment banking
division of Morgan Stanley & Co. Incorporated where he was a member of the
firm's energy group specializing in oil and gas financing and acquisition
transactions. Mr. Hersh is a director of HS Resources, Inc., Petroglyph Energy,
Inc., Titan Exploration, Inc. and Vista Energy Resources, Inc.
 
                                       96
<PAGE>   97
 
Mr. Hersh earned his M.B.A. from the Stanford University Graduate School of
Business, and his undergraduate degree from Princeton University.
 
     James L. Houghton. Mr. Houghton is a certified public accountant and a
graduate of Kansas University with a Bachelor of Science degree in Accounting,
as well as a Bachelor of Laws degree. Mr. Houghton has served as a director of
the Company since August 1997, and as a director of Parker & Parsley from
October 1991 until August 1997. Until October 1, 1991, Mr. Houghton was the lead
oil and gas tax specialist for the accounting firm of Ernst & Young, was a
member of Ernst & Young's National Energy Group, and had served as its Southwest
Regional Director of Tax. Mr. Houghton is a member of the American Institute of
Certified Public Accountants, a member of the Oklahoma Society of Certified
Public Accountants and a former Chairman of its Federal and Oklahoma Taxation
Committee and past President of the Oklahoma Institute on Taxation. He has also
served as a Director for the Independent Petroleum Association of America and as
a member of its Tax Committee.
 
     Jerry P. Jones. Mr. Jones earned a Bachelor of Science degree from West
Texas State College in 1953 and a Bachelor of Law degree from the University of
Texas School of Law in 1959. Mr. Jones has served as a director of the Company
since August 1997, and as a director of Parker & Parsley from May 1991 until
August 1997. Mr. Jones has been an attorney with the law firm of Thompson &
Knight, P.C., Dallas, Texas, since September 1959 and was a shareholder in that
firm until January 1998, when he retired and became of counsel to the firm. Mr.
Jones specialized in civil litigation, especially in the area of energy
disputes.
 
     Richard E. Rainwater. Mr. Rainwater, a graduate of the University of Texas
with a B.A. and the Stanford University Graduate School of Business with an
M.B.A., became a director of the Company in August 1997. He served as a director
of Mesa from July 1996 until August 1997. Since 1986, Mr. Rainwater has been an
independent investor and the sole shareholder and Chairman of Rainwater, Inc.
Mr. Rainwater was the founder of Crescent Real Estate Equities, Inc. in 1994,
and since that time has served as its Chairman of the Board. He was the
co-founder of Mid Ocean Limited in 1991, the founder of Columbia Hospital
Corporation (predecessor to Columbia/HCA Healthcare Corporation) in 1987, and
the founder of ENSCO International, Inc. in 1986. From 1970 until 1986, Mr.
Rainwater served as the Chief Investment Advisor to the Bass Family of Texas.
 
     Charles E. Ramsey, Jr. Mr. Ramsey is a graduate of the Colorado School of
Mines with a Petroleum Engineering degree and a graduate of the Smaller Company
Management program at the Harvard Graduate School of Business Administration.
Mr. Ramsey has served as a director of the Company since August 1997. Mr. Ramsey
served as a director of Parker & Parsley from October 1991 until August 1997.
Since October 1991, he has operated an independent management and financial
consulting firm. From June 1958 until June 1986, Mr. Ramsey held various
engineering and management positions in the oil and gas industry and, for six
years before October 1991, was a Senior Vice President in the Corporate Finance
Department of Dean Witter Reynolds Inc. (Dallas, Texas office). His industry
experience includes 12 years of senior management experience in the positions of
President, Chief Executive Officer and Executive Vice President of May Petroleum
Inc. Mr. Ramsey is also a former director of MBank Dallas, the Dallas Petroleum
Club and Lear Petroleum Corporation.
 
     Philip B. Smith. Mr. Smith, a graduate of Oklahoma State University with a
B.S. in mechanical engineering and the University of Tulsa with an M.B.A., has
served as a director of the Company since August 1997. He served as a director
of Mesa from July 1996 until August 1997. In 1996, Mr. Smith founded PRIZE
Petroleum, L.L.C., an owner of Sunterra Petroleum, L.L.C. From 1991 until 1996,
Mr. Smith served as President, Chief Executive Officer and a director of Tide
West Oil Company. From 1986 until 1991, he served as Senior Vice President of
Mega Natural Gas Company, and from 1980 until 1986 he held executive positions
with two small exploration and production companies. From 1976 until 1980, Mr.
Smith held various positions with Samson Resources Company, and from 1974 until
1976 he was a production engineer with Texaco Inc. Mr. Smith is a director of HS
Resources, Inc.
 
     Robert L. Stillwell. Mr. Stillwell, a graduate of the University of Texas
with a B.B.A. and the University of Texas School of Law with a J.D., has served
as a director of the Company since August 1997. He served as a director of Mesa
from January 1992 until August 1997, as a member of the Advisory Committee of
Mesa,
                                       97
<PAGE>   98
 
L.P., a predecessor of Mesa, from December 1985 until December 1991, and as a
director of Mesa in its original corporate form from 1968 until January 1987.
Mr. Stillwell has been a partner in the law firm of Baker & Botts, L.L.P., for
more than five years.
 
     In addition to the directors of the Company, Edward O. Vetter and John S.
Herrington will serve as Senior Advisors to the Board of Directors until May 31,
1999. Each of Messrs. Vetter and Herrington receives an annual fee of $20,000
cash for his services as Senior Advisor.
 
     Mr. Vetter, a graduate of the Massachusetts Institute of Technology, served
as a director of Parker & Parsley from February 1992 until August 1997, and has
in the past served as director of AMR Corporation, American Airlines, Inc.,
Cabot Corporation, The Western Company of North America and Champion
International Corporation. Since 1977, Mr. Vetter has been President of Edward
O. Vetter & Associates, a management consulting firm in Dallas, Texas. Mr.
Vetter was the Energy Advisor to the Governor of Texas from 1979 to 1983, was
chairman of the Texas Department of Commerce from 1987 to 1991, and was a
Presidential appointee to the U.S. Competitiveness Policy Council. He is a life
trustee of the Massachusetts Institute of Technology and a former member of the
National Petroleum Council.
 
     Mr. Herrington, a graduate of Stanford University with a B.A. in Economics,
and the University of California Hastings College of Law with a J.D. and L.L.B.,
was a director of the Company from August 1997 until May 1998. He served as a
director of Mesa from January 1992 until August 1997. Since December 1991, Mr.
Herrington has been involved in personal investments and real estate activities.
He was Chairman of the Board of Harcourt Brace Jovanovich, Inc. (publishing)
from May 1990 until November 1991, and served as a director from May 1989 until
May 1990. Mr. Herrington served as the Secretary of the Department of Energy of
the United States from February 1985 until May 1990.
 
            SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE
 
     The executive officers and directors of the Company are required to file
reports with the Securities and Exchange Commission, and with the various
Canadian provincial securities commissions (the "Canadian Commissions"),
disclosing the amount and nature of their beneficial ownership in common stock,
as well as changes in that ownership. Pursuant to applicable Canadian policies,
the executive officers and directors of the Company are exempted from filing
reports with the Canadian Commissions, provided that they timely file all
reports required to be filed with the Securities and Exchange Commission.
 
     Based solely on its review of reports and written representations that the
Company has received, the Company is aware that Scott D. Sheffield, the
President and Chief Executive Officer of the Company, did not timely file three
reports on Form 4 covering six transactions effected in 1998. Other than as
discussed above, the Company believes that all required reports were filed on
time for 1998.
 
ITEM 11. EXECUTIVE COMPENSATION
 
     The Company began operations upon completion of the merger of Parker &
Parsley and Mesa on August 7, 1997. Information about management compensation
for periods before that date refers to compensation that either of the
predecessor companies paid.
 
COMPENSATION OF DIRECTORS
 
     Currently, each non-employee director receives an annual retainer fee of
$50,000 if the director serves on a committee and $40,000 if he does not. In
addition, each non-employee director is reimbursed for travel expenses to attend
meetings of the Board of Directors or its committees and an additional $2,500
for services as chairman of a committee. No additional fees are paid for
attendance at board or committee meetings. Executive officers of the Company do
not receive additional compensation for serving on the Board of Directors.
 
     Under the Plan, each non-employee director automatically receives 50
percent (and may elect to receive 100 percent) of the director's annual retainer
fee in the form of common stock instead of cash on the last
 
                                       98
<PAGE>   99
 
business day of the month in which the annual meeting of stockholders is held.
The number of shares included in each award is determined by dividing the
applicable percentage of the annual retainer fee by the closing sale price of
common stock on the business day immediately preceding the date of the award.
When issued, the shares of common stock awarded are subject to transfer
restrictions that lapse on the earlier of the next annual meeting of
stockholders or the first anniversary date of the award if the person has
continued as a director through that date. If a non-employee director's services
as a director are terminated for any reason before the earlier of the next
annual meeting of stockholders or the first anniversary of the date of the
grant, transfer restrictions on some of the shares will lapse (and the rest of
the shares will be forfeited) based on the number of regularly scheduled
meetings of the Board of Directors that were held since the last annual meeting
and the number of regularly scheduled meetings remaining to be held before the
next annual meeting of stockholders. The vesting of ownership and the lapse of
transfer restrictions may be accelerated upon the death, disability or
retirement of the director or a change in control of the Company.
 
     On May 29, 1998, each non-employee director received the following awards
of common stock in lieu of cash retainer fees (which were based on a closing
sale price of $22.8125 for the common stock): Messrs. Brumley, Gardner and Hersh
received awards of 2,191 shares; Messrs. Baroffio and Rainwater received awards
of 1,753 shares; Messrs. Houghton, Jones, Ramsey and Smith received awards of
1,095 shares; and Mr. Stillwell received an award of 876 shares. Messrs.
Brumley, Gardner and Hersh were the only directors who elected to receive 100
percent of their retainers in common stock.
 
COMPENSATION OF EXECUTIVE OFFICERS
 
     The compensation paid to the Company's executive officers generally
consists of base salaries, annual bonuses, awards under the Plan, contributions
to the Company's 401(k) retirement plan, and miscellaneous perquisites. The
following table summarizes the total compensation for 1998, 1997, and 1996
awarded to, earned by or paid to the following persons:
 
                           SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                                        LONG-TERM
                                                                                   COMPENSATION AWARDS
                                                  ANNUAL COMPENSATION            -----------------------
                                         -------------------------------------    VALUE OF      SHARES
                                                                OTHER ANNUAL     RESTRICTED   UNDERLYING      ALL OTHER
NAME AND PRINCIPAL POSITION       YEAR    SALARY    BONUS(a)   COMPENSATION(b)    STOCK(c)    OPTIONS(d)   COMPENSATION(e)
- ---------------------------       ----   --------   --------   ---------------   ----------   ----------   ---------------
<S>                               <C>    <C>        <C>        <C>               <C>          <C>          <C>
I. Jon Brumley(f)...............  1998   $225,000   $    --       $ 60,285       $       --         --        $ 36,445
Chairman of the Board             1997    537,525   360,000        121,198        2,234,625     90,000          36,037
                                  1996    180,142        --             --               --    228,571          18,014
Scott D. Sheffield(g)...........  1998    600,000   216,000         16,734               --     90,000         123,252
President and                     1997    518,875   360,000        838,075        2,234,625     90,000         105,996
Chief Executive Officer           1996    390,000   375,375         47,770               --     70,000          87,990
Dennis E. Fagerstone............  1998    275,000    92,812          8,076               --     35,000          37,757
Executive Vice President          1997    259,387   123,750         61,985          871,125     35,000          27,149
                                  1996    212,490    90,000             --               --     71,428          30,249
Mel Fischer(h)..................  1998    285,000    76,950         18,897               --         --          44,500
Executive Vice President          1997    255,833   128,250        346,438          871,125     56,000          33,787
- -- World Wide Exploration         1996         --        --             --               --         --              --
Mark L. Withrow(g)..............  1998    250,000    84,376         60,882               --     35,000          61,178
Executive Vice President          1997    228,000   112,500        382,020          871,125     35,000          51,835
and General Counsel               1996    175,000   201,737         33,021           59,500     21,000          43,103
M. Garrett Smith................  1998    250,000    84,376          7,457               --     35,000          36,559
Executive Vice President          1997    214,000   105,750         44,386          871,125     35,000          15,812
and Chief Financial Officer       1996    137,490   200,000             --               --     50,000          33,749
</TABLE>
 
- ---------------
 
(a)  Represents the amount awarded under the Company's annual bonus program and
     bonus awards related to specific events. The 1998 annual bonus was approved
     on February 24, 1999, and paid fully in cash. The 1997 annual bonus was
     paid one-half in cash and one-half in restricted common stock. Subject to
     accelerated lapse in certain circumstances, the ownership of the stock
     vests after one year, and transfer restrictions lapse on one-third of the
     shares on each of the first, second and third anniversaries of the date of
     grant. In 1996, Mr. Withrow received one-half of a previously established
     target level bonus in
 
                                       99
<PAGE>   100
 
     restricted stock and the other one-half of target plus any excess above
     target in cash. The number of shares of restricted stock awarded as annual
     bonuses was calculated using the last closing sale price of the common
     stock before the date of the award $(22.375 for 1997 and $30.125 for 1996).
     Ownership of the restricted stock awarded in 1996 vested on August 13, 1997
     and ownership of the restricted stock awarded for 1997 vested on September
     30, 1998 due to the triggering of a vesting acceleration clause contained
     in the Plan.
 
<TABLE>
<CAPTION>
                                                                           RESTRICTED STOCK AWARD
                                                                           -----------------------
                                                                             NUMBER       VALUE
                                                       YEAR   CASH AWARD   OF SHARES    OF SHARES
                                                       ----   ----------   ----------   ----------
   <S>                                                 <C>    <C>          <C>          <C>
   Mr. Brumley.......................................  1998    $     --         --       $     --
                                                       1997     179,993      8,045        180,007
                                                       1996          --         --             --
   Mr. Sheffield.....................................  1998     216,000         --             --
                                                       1997     179,993      8,045        180,007
                                                       1996     375,375         --             --
   Mr. Fagerstone....................................  1998      92,812         --             --
                                                       1997      61,883      2,765         61,867
                                                       1996      90,000         --             --
   Mr. Fischer.......................................  1998      76,950         --             --
                                                       1997      64,123      2,866         64,127
                                                       1996          --         --             --
   Mr. Withrow.......................................  1998      84,376         --             --
                                                       1997      56,249      2,514         56,251
                                                       1996     102,377      1,307         39,373
   Mr. Smith.........................................  1998      84,376         --             --
                                                       1997      52,878      2,363         52,872
                                                       1996     200,000         --             --
</TABLE>
 
     In 1996 Mr. Withrow also received a restricted stock bonus award of 2,436
     shares valued at $59,987 on the date of grant for his role in the
     divestiture of the Company's Australia and Asia subsidiaries. These shares
     vested on April 17, 1997, and the transfer restrictions lapsed one-third on
     April 17, 1997, and the remaining two-thirds lapsed on August 7, 1997.
 
(b)  This column includes (i) gross-up payments in 1997 for taxes in connection
     with the receipt of restricted stock awarded pursuant to the annual bonus
     plan as follows: Mr. Brumley $118,805; Mr. Sheffield $118,805; Mr.
     Fagerstone $40,832; Mr. Fischer $42,328; and Mr. Withrow $37,125; (ii)
     relocation and housing cost of living adjustment related to moving
     corporate headquarters from Midland, Texas to Irving, Texas as follows:
     payment for 1998 -- Mr. Withrow $42,290; payments for 1997 -- Mr. Sheffield
     $432,856; Mr. Fischer $151,777; and Mr. Withrow $204,000; (iii) tax
     gross-up payments for relocation and cost of living adjustment: payment for
     1998 -- Mr. Withrow $12,044; payments for 1997 -- Mr. Sheffield $283,781;
     Mr. Fischer $94,889; and Mr. Withrow $133,742; (iv) temporary housing
     payment to Mr. Fisher of $15,000 in 1998, and $55,000 in 1997, for housing
     in Texas during Mr. Fischer's two year initial employment commitment; (v) a
     1998 payment of $44,998 to Mr. Brumley for unused vacation; and 1997
     payments to Mr. Fagerstone of $21,153 and Mr. Smith for $9,490 for unused
     vacation; (vi) a cash payment to Mr. Sheffield in 1996 of $47,770, which
     was equal to 50 percent of the federal income tax liability associated with
     the cash bonus received in lieu of restricted stock under the annual bonus
     program; and (vii) a 1996 gross-up payment to Mr. Withrow of $33,021
     related to a restricted stock award he received as part of the annual bonus
     plan. Amounts not shown represent miscellaneous perquisites.
 
(c)  The restricted stock awarded in 1997 represents grants on August 8, 1997 of
     59,000 shares of common stock to each of Messrs. Brumley and Sheffield and
     23,000 shares of common stock to each of Messrs. Fagerstone, Fischer,
     Withrow and Smith with vesting restrictions that were to lapse one-half on
 
                                       100
<PAGE>   101
 
     August 8, 2000, and one-half on August 8, 2001. Mr. Brumley's restricted
     stock fully vested effective as of May 15, 1998, in connection with his
     retirement as an employee of the Company. Messrs. Sheffield, Fischer,
     Fagerstone, Withrow and Smith's restricted stock fully vested on September
     30, 1998 due to the triggering of a vesting acceleration clause contained
     in the Plan. In 1996 Mr. Withrow received a restricted stock award of 2,000
     shares of common stock with vesting restrictions that were to lapse
     November 19, 1999. The merger of Parker & Parsley and Mesa to form the
     Company accelerated the lapse of these restrictions to August 7, 1997. The
     values of the awards were calculated using the closing sale price of the
     common stock of $37.875 on August 7, 1997, and of $29.75 on November 18,
     1996. Because all vesting restrictions on all restricted stock heretofore
     awarded to each executive officer have lapsed (either by their terms or
     through acceleration upon the happening of certain events) no executive
     officer held any shares of restricted stock on December 31, 1998.
 
(d)  Stock options that Mesa awarded to Messrs. Brumley, Fagerstone and Smith
     before the merger were converted to options to purchase common stock on a
     1-for-7 basis.
 
(e)  For 1998 this column includes (i) contributions to qualified retirement
     plans for Messrs. Brumley, Sheffield, Fagerstone, Fischer, Withrow and
     Smith of $7,916, $16,000, $9,728, $16,000, $16,000 and $11,222,
     respectively; (ii) contributions to the Company's non-qualified deferred
     compensation retirement plan for Messrs. Brumley, Sheffield, Fagerstone,
     Fischer, Withrow and Smith of $28,529, $61,154, $28,029, $28,500, $25,481
     and $25,337, respectively; (iii) deemed payment for one-third of the
     principal and all accrued interest to Mr. Sheffield for $44,768 and Mr.
     Withrow for $19,697 related to a 1995 stock acquisition loan program; and
     (iv) a $1,330 premium with respect to a term life insurance policy for the
     benefit of Mr. Sheffield.
 
(f)  Mr. Brumley became an officer of Mesa in August 1996. He ceased to be an
     employee of the Company effective May 15, 1998, but continues to serve as
     Chairman of the Board of Directors.
 
(g)  See "Compensation of Executive Officers -- Employee Investment
     Partnerships" below for information about Parker & Parsley-sponsored
     employee investment partnerships in which Mr. Sheffield and Mr. Withrow
     invested their own funds.
 
(h)  Mr. Fischer became an officer of Parker & Parsley in February 1997. Mr.
     Fischer retired from the Company effective February 15, 1999.
 
     Long-Term Incentive Plan. The Plan provides for employee awards in the form
of stock options, stock appreciation rights, restricted stock, and performance
units payable in stock or cash. The maximum number of shares of common stock
that may be issued under the Plan is equal to 10 percent of the total number of
shares of common stock outstanding from time to time minus the total number of
shares of stock subject to outstanding awards on the date of calculation under
any other stock-based plan for employees or directors of the Company and its
subsidiaries. The Plan had 5,743,511 shares available for additional awards at
December 31, 1998.
 
     Information about restricted stock awards made under the Plan is set forth
in the Summary Compensation Table. No performance units or stock appreciation
rights have been awarded under the Plan.
 
                                       101
<PAGE>   102
 
     The following table sets forth information about stock option grants made
during 1998 to the named executive officers.
 
                       OPTION GRANTS IN LAST FISCAL YEAR
 
<TABLE>
<CAPTION>
                                          INDIVIDUAL GRANTS
                           ------------------------------------------------
                              NUMBER OF        % OF TOTAL
                             SECURITIES      OPTIONS GRANTED   EXERCISE OR
                             UNDERLYING       TO EMPLOYEES      BASE PRICE      EXPIRATION     GRANT DATE
NAME                       OPTIONS GRANTED   IN FISCAL YEAR    PER SHARE(c)        DATE         VALUE(d)
- ----                       ---------------   ---------------   ------------     ----------     ----------
<S>                        <C>               <C>               <C>            <C>              <C>
Mr. Brumley..............          --               --               --             --               --
Mr. Sheffield............      45,000(a)          2.10            17.25          9/30/03        298,800
                               45,000(b)          2.10            14.00       11/23/04-05-06    279,000
Mr. Fagerstone...........      17,500(a)          0.81            17.25          9/30/03        116,200
                               17,500(b)          0.81            14.00       11/23/04-05-06    108,500
Mr. Fischer..............      17,500(a)          0.81            17.25          9/30/03        116,200
                               17,500(b)          0.81            14.00       11/23/04-05-06    108,500
Mr. Withrow..............      17,500(a)          0.81            17.25          9/30/03        116,200
                               17,500(b)          0.81            14.00       11/23/04-05-06    108,500
Mr. Smith................      17,500(a)          0.81            17.25          9/30/03        116,200
                               17,500(b)          0.81            14.00       11/23/04-05-06    108,500
</TABLE>
 
- ---------------
 
(a)  These options were granted on August 19, 1998, fully vested on September
     30, 1998 due to the triggering of a vesting acceleration clause contained
     in the Plan, and expire September 30, 2003.
 
(b)  These options were granted on November 23, 1998, vest at the rate of
     one-third each year commencing on the first anniversary of the grant date,
     and have a term of five years from the date of vesting. The Compensation
     Committee retains discretion, subject to plan limits, to modify the terms
     of the options. In the event of a change in control of the Company as
     defined in the Plan, the options will immediately become fully vested and
     exercisable in full.
 
(c)  The exercise price per share is equal to the closing price of the common
     stock on the New York Stock Exchange composite tape on the day before the
     date of grant.
 
(d)  The estimated grant date value of shares in footnotes (a) and (b) is
     determined using the Black-Scholes model. The material assumptions and
     adjustments incorporated in the Black-Scholes model in estimating the value
     of the options include the following:
 
     - An interest rate of 5.43 percent for footnote (a) and 5.5 percent for
       footnote (b), which represents the interest rate on a U.S. Treasury
       security with a maturity date corresponding to the option term.
 
     - Volatility of .309 percent for footnote (a) and .398 percent for footnote
       (b) calculated using daily stock prices for the 120-day period prior to
       the grant date.
 
     - Dividends at the rate of $.10 per share representing the annualized
       dividends paid with respect to a share of common stock at the date of
       grant.
 
     No other adjustments were made to the model for non-transferability or risk
     of forfeiture. The ultimate values of the options will depend on the future
     market price of the common stock, which cannot be forecast with reasonable
     accuracy. The actual value, if any, an optionee will realize upon exercise
     of an option will depend on the excess of the market value of the common
     stock over the exercise price on the date the option is exercised.
 
                                       102
<PAGE>   103
 
     The following table sets forth, for each named executive officer,
information concerning the exercise of stock options during 1998 and the value
of unexercised stock options as of December 31, 1998.
 
                AGGREGATED OPTION EXERCISES IN LAST FISCAL YEAR
                       AND FISCAL YEAR END OPTION VALUES
 
<TABLE>
<CAPTION>
                                                        NUMBER OF SECURITIES          VALUE OF UNEXERCISED
                             NUMBER OF                 UNDERLYING UNEXERCISED             IN-THE-MONEY
                              SHARES                 OPTIONS AT FISCAL YEAR END    OPTIONS AT FISCAL YEAR END
                            ACQUIRED ON    VALUE     ---------------------------   ---------------------------
                             EXERCISE     REALIZED   EXERCISABLE   UNEXERCISABLE   EXERCISABLE   UNEXERCISABLE
                            -----------   --------   -----------   -------------   -----------   -------------
<S>                         <C>           <C>        <C>           <C>             <C>           <C>
Mr. Brumley...............        --          --       318,571            --              --            --
Mr. Sheffield.............        --          --       305,350        45,000              --            --
Mr. Fagerstone............        --          --       132,498        17,500              --            --
Mr. Fischer...............        --          --        73,500        17,500              --            --
Mr. Withrow...............        --          --        94,500        17,500              --            --
Mr. Smith.................        --          --       106,071        17,500              --            --
</TABLE>
 
     Retirement Plan. The Company provides a non-qualified deferred compensation
retirement plan for officers and key employees of the Company. Each participant
is allowed to contribute up to 25 percent of base salary. The Company provides a
matching contribution of 100 percent of the participant's contribution limited
to the first 10 percent of the officer's base salary (or 8 percent of the key
employee's base salary). The Company matching contribution vests immediately.
 
     In December 1998, the Company received information that an investment fund
group had acquired beneficial ownership of more than 20 percent of the common
stock. Pursuant to the provisions of the Company's deferred compensation
retirement plan, if a third party acquires 20 percent or more of the common
stock certain change in control provisions contained in the Plan are triggered.
Accordingly, in December 1998, the Compensation Committee determined that a
change in control had occurred, effective September 30, 1998, under the deferred
compensation retirement plan. Consequently, all of the contributions made to the
deferred compensation retirement plan from August 1997 to December 15, 1998 were
distributed to the respective officers and key employees.
 
     Employee Investment Partnerships. From 1987 through 1991, Parker & Parsley
formed employee partnership programs in which Mr. Sheffield participated. In
1992 and 1993 Mr. Sheffield and Mr. Withrow participated in a Direct Investment
Partnership formed to invest in all wells drilled by Parker & Parsley during
those years (except in certain circumstances where its participation would
impose additional costs to Parker & Parsley). As of December 31, 1998, the
aggregate contributions that have been made to the employee partnerships and the
Direct Investment Partnerships by Mr. Sheffield and Mr. Withrow and the
aggregate distributions that have been received by them from those partnerships
were as follows: Mr. Sheffield contributed $734,955 and received $1,066,125
($111,542 of which was received during 1998); and Mr. Withrow contributed
$142,625 and received $138,231 ($18,416 of which was received during 1998).
 
     Severance Agreements. On August 8, 1997, the Company entered into severance
agreements with its officers. Salaries and bonuses are set by the Compensation
Committee independent of these agreements, and the Compensation Committee can
increase or reduce base salaries at its discretion.
 
     Either the Company or the officer may terminate the officer's employment
under the severance agreement at any time. The Company must pay the officer an
amount equal to one year's base salary if the officer's employment is terminated
because of death, disability, or normal retirement. The Company must pay the
officer an amount equal to one year's base salary and continue health insurance
for the officer's family for one year if the Company terminates the officer's
employment without cause or if the officer terminates employment for good
reason, which is when reductions in the officer's base annual salary exceed
specified limits or when the officer's responsibilities have been significantly
reduced. If within one year after a change in control of the Company, the
Company terminates the officer without cause or if the officer terminates
employment for good reason, the Company must pay the officer an amount equal to
2.99 times the sum of the
 
                                       103
<PAGE>   104
 
officer's base salary plus target bonus for the year and continue health
insurance for the officer's family for one year. If the officer terminates
employment with the Company without reason between six months and one year after
a change in control, or at any time within one year after a change in control if
the officer is required to move, then the Company must pay the officer one
year's base salary and continue health insurance for the officer's family for
one year. Officers are also entitled to additional payments for certain tax
liabilities that may apply to severance payments following a change in control.
 
     Indemnification Agreements. The Company has entered into indemnification
agreements with each of its directors and officers, including the named
executive officers. Those agreements require the Company to indemnify the
directors and officers to the fullest extent permitted by the Delaware General
Corporation Law and to advance expenses in connection with certain claims
against directors and officers. The Company expects to enter into similar
agreements with persons selected to be directors and officers in the future.
Each indemnification agreement also provides that, upon a potential change in
control of the Company and if the indemnified director or officer so requests,
the Company will create a trust for the benefit of the indemnified director or
officer in an amount sufficient to satisfy payment of all liabilities and suits
against which the Company has indemnified the director or officer.
 
          COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
     Mr. Kenneth A. Hersh is a member of the Compensation Committee and is a
vice-president of Rainwater, Inc. Effective January 1, 1999, the Company entered
into an agreement with Rainwater, Inc., the former general partner of DNR-MESA
Holdings, L.P. ("DNR"), modifying certain terms of a prior agreement between DNR
and Mesa, which was assumed by the Company upon consummation of the merger
between Parker & Parsley and Mesa. Pursuant to the terms of this agreement, as
modified, the Company will pay Rainwater, Inc. $300,000 per year and reimburse
Rainwater, Inc. for certain expenses in consideration for consulting and
financial analysis services provided to the Company by Rainwater, Inc. and its
representatives.
 
                                       104
<PAGE>   105
 
ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
 
     The following table sets forth certain information regarding the beneficial
ownership of common stock as of February 26, 1999, by (a) each person who is
known by the Company to own beneficially more than 5 percent of the outstanding
shares of common stock, (b) each director and nominee for director of the
Company, (c) each executive officer of the Company, and (d) all directors and
executive officers as a group.
 
<TABLE>
<CAPTION>
                                                              NUMBER OF    PERCENTAGE
NAME OF PERSON OR IDENTITY OF GROUP                             SHARES     OF CLASS(1)
- -----------------------------------                           ----------   -----------
<S>                                                           <C>          <C>
Beneficial Owners:
  Southeastern Asset Management, Inc.(2)....................  26,434,632      26.4
  Longleaf Partners Fund
  O. Mason Hawkins
     6410 Poplar Avenue, Suite 900
     Memphis, Tennessee 38119
  The Prudential Insurance Company of America(3)............  10,210,987      10.2
     751 Broad Street
     Newark, New Jersey 07102-3777
Management:
  Richard E. Rainwater(4)...................................   5,518,267       5.9
     777 Main Street, Suite 2700
     Fort Worth, Texas 76102
  I. Jon Brumley(5).........................................     687,283         *
  Scott D. Sheffield(5),(6).................................     640,770         *
  Timothy L. Dove(5),(7)....................................     141,795         *
  Dennis E. Fagerstone(5)...................................     163,405         *
  Lon C. Kile(5),(8)........................................     172,965         *
  M. Garrett Smith(5).......................................     129,149         *
  Mark L. Withrow(5),(9)....................................     155,719         *
  James R. Baroffio.........................................       4,753         *
  R. Hartwell Gardner.......................................      12,489         *
  Kenneth A. Hersh..........................................      10,671         *
  James L. Houghton(10).....................................      13,040         *
  Jerry P. Jones............................................      15,552         *
  Charles E. Ramsey, Jr.....................................      17,086         *
  Philip B. Smith...........................................      42,674         *
  Robert L. Stillwell(11)...................................       6,649         *
  All directors and executive officers as a group (16
     persons)(12)...........................................   7,732,267       8.3
</TABLE>
 
- ---------------
 
  *  Does not exceed 1 percent.
 
 (1) Based on 100,300,023 shares of common stock consisting of 94,099,256
     outstanding shares of common stock and 6,200,767 outstanding exchangeable
     shares that are exchangeable for the same number of shares of common stock.
 
 (2) The Schedule 13G/A filed with the SEC on February 10, 1999, which is a
     joint statement on Schedule 13G/A filed by Southeastern Asset Management,
     Inc. ("Southeastern"), Longleaf Partners Fund ("Longleaf") and O. Mason
     Hawkins ("Hawkins"), states that the statement is being filed by
     Southeastern as a registered investment adviser, and that all of the
     securities covered by the statement are owned legally by Southeastern's
     investment advisory clients and none are owned directly or indirectly by
     Southeastern. The Schedule 13G/A further states that the statement is also
     being filed by Hawkins, Chairman of the Board and C.E.O. of Southeastern,
     in the event he could be deemed to be a controlling person of that firm as
     the result of his official positions with or ownership of its voting
     securities. The existence of such control is expressly disclaimed. Hawkins
     does not own directly or indirectly any securities covered by the Schedule
     13G/A for his own account.
                                       105
<PAGE>   106
 
 (3) The Schedule 13G/A filed with the SEC on January 27, 1999 states that The
     Prudential Insurance Company of America may have direct or indirect voting
     and/or investment discretion over 10,210,987 shares or 10.2 percent of the
     outstanding common stock which are held for the benefit of its clients by
     its separate accounts, externally managed accounts, registered investment
     companies, subsidiaries and/or other affiliates.
 
 (4) Includes 109,324 shares owned directly by Rainwater, Inc., of which Mr.
     Rainwater is the sole shareholder, and 247,710 shares (of which Mr.
     Rainwater disclaims beneficial ownership) owned by Mr. Rainwater's spouse.
 
 (5) Includes the following number of shares subject to stock options that were
     exercisable at or within 60 days after March 31, 1999: Mr. Brumley,
     318,571; Mr. Sheffield, 305,350; Mr. Dove, 100,500; Mr. Fagerstone,
     132,498; Mr. Kile, 101,500; Mr. Smith, 106,071; and Mr. Withrow, 94,500;
 
 (6) Includes 1,270 shares held by a minor child of Mr. Sheffield and 766 shares
     held in Mr. Sheffield's 401(k) account.
 
 (7) Includes 370 shares held in Mr. Dove's 401(k) account.
 
 (8) Includes 586 shares held in Mr. Kile's 401(k) account.
 
 (9) Includes 4,328 shares held in Mr. Withrow's 401(k) account.
 
(10) Includes 10,945 shares held by two trusts of which Mr. Houghton is a
     trustee and over which shares he has sole voting and investment power, and
     1,000 shares held in Mr. Houghton's investment retirement account.
 
(11) Includes 758 shares held by Mr. Stillwell's wife.
 
(12) Includes 1,158,990 shares of common stock subject to stock options that
     were exercisable at or within 60 days after February 26, 1999.
 
ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
 
     The Company, through its wholly-owned subsidiaries, has in the past
sponsored certain affiliated partnerships, including 35 public and nine private
drilling partnerships and three public income partnerships, all of which were
formed primarily for the purpose of drilling and completing wells or acquiring
producing properties. In accordance with the terms of the partnership agreements
and the related tax partnership agreements of the affiliated partnerships, the
Company participated in the activities of the sponsored partnerships on a
promoted basis. In 1992, the Company discontinued sponsoring public and private
oil and gas development drilling and income partnerships.
 
     During each of 1994, 1993 and 1992, the Company formed a Direct Investment
Partnership for the purpose of permitting selected key employees to invest
directly, on an unpromoted basis, in wells that the Company drills. The partners
in the Direct Investment Partnerships formed in 1994, 1993 and 1992 pay and
receive approximately .337 percent, 1.5375 percent and 1.865 percent,
respectively, of the costs and revenues attributable to the Company's interest
in the wells in which each such Direct Investment Partnership participates. The
Company discontinued the formation of Direct Investment Partnerships in 1995.
 
     The Company, through a wholly-owned subsidiary, serves as operator of
properties in which it and its affiliated partnerships have an interest.
Accordingly, the Company receives producing well overhead, drilling well
overhead and other fees related to the operation of the properties. The
affiliated partnerships also reimburse the Company for their allocated share of
general and administrative charges.
 
     Effective January 1, 1999, the Company entered into an agreement with
Rainwater, Inc., the former general partner of DNR that Mr. Rainwater wholly
owns, modifying certain terms of a prior agreement between DNR and Mesa, which
was assumed by the Company upon consummation of the merger between Parker &
Parsley and Mesa. Pursuant to the terms of this agreement, as modified, the
Company will pay Rainwater, Inc. $300,000 per year and reimburse Rainwater, Inc.
for certain expenses in consideration for consulting and financial analysis
services provided to the Company by Rainwater, Inc. and its representatives.
 
                                       106
<PAGE>   107
 
     Brumley Partners, a Texas general partnership consisting of I. Jon Brumley,
the Company's Chairman of the Board, and a family member, was admitted as a
limited partner with a profits interest in DNR pursuant to the Amended and
Restated Agreement of Limited Partnership of DNR dated November 8, 1996. Until
March 23, 1998, DNR was a major holder of shares of common stock. On March 23,
1998, DNR distributed to its partners most of its common stock holdings, which
resulted in a distribution to Brumley Partners of 310,344 shares of common stock
having a net value of $8,243,513 at the distribution date.
 
     Robert L. Stillwell, a director of the Company, is a partner of Baker &
Botts, L.L.P., which provided various legal services to the Company during 1997.
Baker & Botts, L.L.P. was Mesa's primary outside corporate counsel. The dollar
amount of fees that the Company paid to Baker & Botts, L.L.P. during the most
recent fiscal year of that law firm did not exceed 5 percent of that firm's
gross revenues for that year.
 
                                    PART IV
 
ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K
 
  LISTING OF FINANCIAL STATEMENTS AND EXHIBITS
 
FINANCIAL STATEMENTS
 
     The following consolidated financial statements of the Company are included
in "Item 8. Financial Statements and Supplementary Data":
 
    Independent Auditors' Reports
     Consolidated Balance Sheets as of December 31, 1998 and 1997
     Consolidated Statements of Operations and Comprehensive Income
       (Loss) for the years ended December 31, 1998, 1997 and 1996
     Consolidated Statements of Stockholders' Equity for the years ended
    December 31, 1998, 1997 and 1996
     Consolidated Statements of Cash Flows for the years ended December 31,
    1998, 1997 and 1996
     Notes to Consolidated Financial Statements
     Unaudited Supplementary Information
 
     All other statements and schedules for which provision is made in the
applicable accounting regulations of the SEC have been omitted because they are
not required under related instructions or are inapplicable, or the information
is shown in the financial statements and related notes.
 
EXHIBITS
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
          2.1            -- Amended and Restated Agreement and Plan of Merger, dated
                            as of April 6, 1997, by and among MESA Inc. ("Mesa"),
                            Mesa Operating Co. ("MOC"), MXP Reincorporation Corp. and
                            Parker & Parsley Petroleum Company ("Parker & Parsley")
                            (incorporated by reference to Exhibit 2.1 to the
                            Company's Registration Statement on Form S-4, dated June
                            27, 1997, Registration No. 333-26951).
          3.1            -- Amended and Restated Certificate of Incorporation of the
                            Company (incorporated by reference to Exhibit 3.1 to the
                            Company's Registration Statement on Form S-4, dated June
                            27, 1997, Registration No. 333-26951).
          3.2            -- Restated Bylaws of the Company (incorporated by reference
                            to Exhibit 3.2 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
          3.3            -- Certificate of Designations of Special Preferred Voting
                            Stock (incorporated by reference to Exhibit 3.3 of the
                            Company's Registration Statement on Form S-3,
                            Registration No. 333-42315, filed with the SEC on
                            December 17, 1997).
</TABLE>
 
                                       107
<PAGE>   108
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
          3.4            -- Terms and Conditions of Exchangeable Shares (incorporated
                            by reference to Annex F to the Definitive Joint
                            Management Information Circular and Proxy Statement of
                            the Company and Chauvco Resources Ltd. ("Chauvco"), File
                            No. 001-13245, filed with the SEC on November 17, 1997).
          4.1            -- Form of Certificate of Common Stock, par value $.01 per
                            share, of the Company (incorporated by reference to
                            Exhibit 4.1 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
          4.2            -- Form of Certificate of Special Preferred Voting Stock
                            (incorporated by reference to Exhibit 4.1 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
          4.3            -- Form of Certificate of Exchangeable Shares (incorporated
                            by reference to Exhibit 4.2 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
          9.1            -- Voting and Exchange Trust Agreement, dated as of December
                            18, 1997, among the Company, Pioneer Natural Resources
                            (Canada) Ltd. ("Pioneer Canada") and Montreal Trust
                            Company of Canada, as Trustee (incorporated by reference
                            to Exhibit 2.4 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
          9.2            -- Amended and Restated Shareholders Agreement, dated as of
                            September 3, 1997, by and between the Company and Guy J.
                            Turcotte (incorporated by reference to Exhibit 2.6 to the
                            Company's Registration Statement on Form S-3,
                            Registration No. 333-42315, filed with the SEC on
                            December 15, 1997).
          9.3            -- Shareholders Agreement, dated as of September 3, 1997, by
                            and among the Company, Trimac Corporation and Gendis Inc.
                            (incorporated by reference to Exhibit 2.4 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on October 2, 1997).
         10.1            -- Indenture, dated July 2, 1996, among Pioneer USA
                            (formerly MOC), as Issuer, the Company, as Guarantor, and
                            Harris Trust and Savings Bank, as Trustee, relating to
                            the 11 5/8% Senior Subordinated Discount Notes Due 2006
                            (incorporated by reference to Exhibit 4.17 to Mesa's
                            Quarterly Report on Form 10-Q for the period ended June
                            30, 1996).
         10.2            -- First Supplemental Indenture, dated as of April 15, 1997,
                            among Pioneer USA (formerly MOC), as Issuer, Mesa, the
                            subsidiary guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.1 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.3            -- Second Supplemental Indenture, dated as of August 7,
                            1997, among Pioneer USA (formerly MOC), as Issuer, Mesa,
                            the subsidiary guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.2 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.4            -- Third Supplemental Indenture, dated as of December 18,
                            1997, among Pioneer USA, the Subsidiary Guarantors named
                            therein, the Company, and Harris Trust and Savings Bank,
                            as Trustee, with respect to the indenture identified
                            above as Exhibit 10.1 (incorporated by reference to
                            Exhibit 10.12 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
</TABLE>
 
                                       108
<PAGE>   109
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.5            -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA (formerly MOC), a Delaware
                            corporation, the Company, a Delaware corporation, Pioneer
                            NewSub1, Inc., a Texas corporation, and Harris Trust and
                            Savings Bank, an Illinois corporation, as Trustee, with
                            respect to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.13 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.6            -- Fifth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer NewSub1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, the Company, a
                            Delaware corporation, Pioneer DebtCo., Inc., a Texas
                            corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.1 (incorporated
                            by reference to Exhibit 10.14 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.7            -- Sixth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo. Inc. (as successor to Pioneer
                            NewSub1, Inc.), a Texas corporation, the Company, a
                            Delaware corporation, and Harris Trust and Savings Bank,
                            an Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.1 (incorporated
                            by reference to Exhibit 10.15 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.8            -- Indenture, dated July 2, 1996, among Pioneer USA
                            (formerly MOC), as Issuer, the Company (Mesa's
                            successor), as Guarantor, and Harris Trust and Savings
                            Bank, as Trustee, relating to the 10 5/8% Senior
                            Subordinated Notes Due 2006 (incorporated by reference to
                            Exhibit 4.18 to Mesa's Quarterly Report on Form 10-Q for
                            the period ended June 30, 1996).
         10.9            -- First Supplemental Indenture, dated as of April 15, 1997,
                            among Pioneer USA (formerly MOC), as Issuer, Mesa, the
                            Subsidiary Guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.8
                            (incorporated by reference to Exhibit 10.3 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.10           -- Second Supplemental Indenture, dated as of August 7,
                            1997, among Pioneer USA (formerly MOC), as Issuer, Mesa,
                            the Subsidiary Guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.8
                            (incorporated by reference to Exhibit 10.4 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.11           -- Third Supplemental Indenture, dated as of December 18,
                            1997, among Pioneer USA, the Subsidiary Guarantors named
                            therein, the Company, and Harris Trust and Savings Bank,
                            as Trustee, with respect to the indenture identified
                            above as Exhibit 10.8 (incorporated by reference to
                            Exhibit 10.6 to the Company's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 2,
                            1998).
         10.12           -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA, a Delaware corporation, the
                            Company, a Delaware corporation, Pioneer NewSub1, Inc., a
                            Texas corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.7 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
</TABLE>
 
                                       109
<PAGE>   110
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.13           -- Fifth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer NewSub 1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, the Company, a
                            Delaware corporation, Pioneer DebtCo., Inc., a Texas
                            corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.8 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.14           -- Sixth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo, Inc. (as successor to Pioneer
                            NewSub1, Inc.), a Texas corporation, the Company, a
                            Delaware corporation, and Harris Trust and Savings Bank,
                            an Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.9 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.15           -- Indenture, dated April 12, 1995, between Pioneer USA
                            (successor to Parker & Parsley), and The Chase Manhattan
                            Bank (National Association), as Trustee (incorporated by
                            reference to Exhibit 4.1 to Parker & Parsley's Current
                            Report on Form 8-K, dated April 12, 1995, File No.
                            001-10695).
         10.16           -- First Supplemental Indenture, dated as of August 7, 1997,
                            among Parker & Parsley, The Chase Manhattan Bank, as
                            Trustee, and Pioneer USA, with respect to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 10.5 to the Company's Quarterly
                            Report on Form 10-Q for the period ended September 30,
                            1997, File No. 001-13245).
         10.17           -- Second Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA, a Delaware corporation, Pioneer
                            NewSub1, Inc., a Texas corporation, and The Chase
                            Manhattan Bank, a New York banking association, as
                            Trustee, with respect to the indenture identified above
                            as Exhibit 10.15 (incorporated by reference to Exhibit
                            10.17 to the Company's Current Report on Form 8-K, File
                            No. 001-13245, filed with the SEC on January 2, 1998).
         10.18           -- Third Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer New Sub1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, Pioneer DebtCo, Inc.,
                            a Texas corporation, and The Chase Manhattan Bank, a New
                            York banking association, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.15 (incorporated
                            by reference to Exhibit 10.18 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.19           -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo, Inc. (as successor to Pioneer
                            NewSub1, Inc., as successor to Pioneer USA), a Texas
                            corporation, the Company, a Delaware corporation, Pioneer
                            USA, a Delaware corporation, and The Chase Manhattan
                            Bank, a New York banking association, as trustee, with
                            respect to the indenture identified above as Exhibit
                            10.15 (incorporated by reference to Exhibit 10.19 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.20           -- Guarantee, dated as of December 30, 1997, by Pioneer USA
                            relating to the $150,000,000 in aggregate principal
                            amount of 8 7/8% Senior Notes due 2005 and $150,000,000
                            in aggregate principal amount of 8 1/4% Senior Notes due
                            2007 issued under the indenture identified above as
                            Exhibit 10.15 (incorporated by reference to Exhibit 10.20
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
</TABLE>
 
                                       110
<PAGE>   111
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.21           -- Form of 8 7/8% Senior Notes due 2005, dated as of April
                            12, 1995, in the aggregate principal amount of
                            $150,000,000, together with Officers' Certificate dated
                            April 12, 1995, establishing the terms of the 8 7/8%
                            Senior Notes due 2005 pursuant to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 4.2 to Parker & Parsley's Quarterly
                            Report on Form 10-Q for the period ended June 30, 1995,
                            File No. 001-10695).
         10.22           -- Form of 8 1/4% Senior Notes due 2007, dated as of August
                            22, 1995, in the aggregate principal amount of
                            $150,000,000, together with Officers' Certificate dated
                            August 22, 1995, establishing the terms of the 8 1/4%
                            Senior Notes due 2007 pursuant to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 1.2 to Parker & Parsley's Current
                            Report on Form 8-K, dated August 17, 1995, File No.
                            001-10695).
         10.23           -- Indenture, dated January 13, 1998, between the Company
                            and The Bank of New York, as Trustee (incorporated by
                            reference to Exhibit 99.1 to the Company's and Pioneer
                            USA's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 14, 1998).
         10.24           -- First Supplemental Indenture, dated as of January 13,
                            1998, among the Company, Pioneer USA, as the Subsidiary
                            Guarantor, and The Bank of New York, as Trustee, with
                            respect to the indenture identified above as Exhibit
                            10.23 (incorporated by reference to Exhibit 99.2 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
         10.25           -- Form of 6.50% Senior Notes due 2008 of the Company
                            (incorporated by reference to Exhibit 99.3 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
         10.26           -- Form of 7.20% Senior Notes due 2028 of the Company
                            (incorporated by reference to Exhibit 99.4 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
         10.27           -- Guarantee (2008 Notes), dated as of January 13, 1998,
                            entered into by Pioneer USA (incorporated by reference to
                            Exhibit 99.5 to the Company's and Pioneer USA's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 14, 1998).
         10.28           -- Guarantee (2028 Notes), dated as of January 13, 1998,
                            entered into by Pioneer USA (incorporated by reference to
                            Exhibit 99.6 to the Company's and Pioneer USA's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 14, 1998).
         10.29           -- Amended and Restated Credit Facility Agreement (Primary
                            Facility), dated as of December 18, 1997, between the
                            Company, as Borrower, and NationsBank of Texas, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, and The Chase Manhattan Bank, as
                            Syndication Agent; and the other Co-Agents and lenders
                            named therein (incorporated by reference to Exhibit 10.1
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
</TABLE>
 
                                       111
<PAGE>   112
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.30*          -- First Amendment to Amended and Restated Credit Facility
                            Agreement (Primary Facility), dated as of June 29, 1998,
                            by and among the Company, as Borrower, NationsBank, N.A.,
                            as Administrative Agent, CIBC Inc., as Documentation
                            Agent, Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, The Chase Manhattan Bank, as
                            Syndication Agent, and the Co-Agents and other lenders
                            signatory thereto.
         10.31           -- Amended and Restated Credit Facility Agreement (364 Day
                            Facility), dated as of December 18, 1997, between the
                            Company, as Borrower, and NationsBank of Texas, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, and The Chase Manhattan Bank, as
                            Syndication Agent; and the other Co-Agents and lenders
                            named therein (incorporated by reference to Exhibit 10.2
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
         10.32*          -- First Amendment to Amended and Restated Credit Facility
                            Agreement (364 Day Facility), dated as of June 29, 1998,
                            by and among the Company, as Borrower, NationsBank, N.A.,
                            as Administrative Agent, CIBC Inc., as Documentation
                            Agent, Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, The Chase Manhattan Bank, as
                            Syndication Agent, and the Co-Agents and other lenders
                            signatory thereto.
         10.33           -- Credit Agreement, dated as of December 18, 1997, among
                            Chauvco, Canadian Imperial Bank of Commerce, as Agent,
                            and the other lenders named therein (incorporated by
                            reference to Exhibit 10.3 to the Company's Current Report
                            on Form 8-K, File No. 001-13245, filed with the SEC on
                            January 2, 1998).
         10.34*          -- First Amending Agreement, dated June 29, 1998, among
                            Pioneer Natural Resources Canada Inc. (formerly Chauvco),
                            Canadian Imperial Bank of Commerce, and the lenders
                            thereto, with respect to the Credit Agreement identified
                            above as Exhibit 10.33.
         10.35           -- Note, dated December 22, 1997, between the Company, as
                            Borrower, and NationsBank of Texas, N.A., as lender
                            (incorporated by reference to Exhibit 10.21 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.36+          -- 1991 Stock Option Plan of Mesa (incorporated by reference
                            to Exhibit 10(v) to Mesa's Annual Report on Form 10-K for
                            the period ended December 31, 1991).
         10.37+          -- 1996 Incentive Plan of Mesa (incorporated by reference to
                            Exhibit 10.28 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
         10.38+          -- Parker & Parsley Long-Term Incentive Plan, dated February
                            19, 1991 (incorporated by reference to Exhibit 4.1 to
                            Parker & Parsley's Registration Statement on Form S-8,
                            Registration No. 33-38971).
         10.39+          -- First Amendment to the Parker & Parsley Long-Term
                            Incentive Plan, dated August 23, 1991 (incorporated by
                            reference to Exhibit 10.2 to Parker & Parsley's
                            Registration Statement on Form S-1, dated February 28,
                            1992, Registration No. 33-46082).
         10.40+          -- The Company's Long-Term Incentive Plan (incorporated by
                            reference to Exhibit 4.1 to the Company's Registration
                            Statement on Form S-8, Registration No. 333-35087).
</TABLE>
 
                                       112
<PAGE>   113
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.41+          -- The Company's Employee Stock Purchase Plan (incorporated
                            by reference to Exhibit 4.1 to the Company's Registration
                            Statement on Form S-8, Registration No. 333-35165).
         10.42*          -- Amendment No. 1 to the Company's Employee Stock Purchase
                            Plan, dated December 9, 1998.
         10.43+          -- The Company's Deferred Compensation Retirement Plan
                            (incorporated by reference to Exhibit 4.1 to the
                            Company's Registration Statement on Form S-8,
                            Registration No. 333-39153).
         10.44+          -- Pioneer USA 401(k) Plan (incorporated by reference to
                            Exhibit 4.1 to the Company's Registration Statement on
                            Form S-8, Registration No. 333-39249).
         10.45+          -- Pioneer USA Matching Plan (incorporated by reference to
                            Exhibit 10.42 to the Company's Annual Report on Form 10-K
                            for the year ended December 31, 1997, File No.
                            001-13245).
         10.46+          -- Omnibus Amendment to Nonstatutory Stock Option
                            Agreements, included as part of the Parker & Parsley
                            Long-Term Incentive Plan, dated as of November 16, 1995,
                            between Parker & Parsley and Named Executive Officers
                            identified on Schedule 1 setting forth additional details
                            relating to the Parker & Parsley Long-Term Incentive Plan
                            (incorporated by reference to Parker & Parsley's Annual
                            Report on Form 10-K for the year ended December 31, 1995,
                            File No. 001-10695).
         10.47+          -- Mesa Management Severance Plan, dated April 4, 1997,
                            including a Schedule of Participants on Schedule A for
                            the purpose of defining the payment of certain benefits
                            upon the termination of the officer's employment under
                            certain circumstances (incorporated by reference to
                            Exhibit 10.29 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
         10.48+          -- Severance Agreement, dated as of August 8, 1997, between
                            the Company and Scott D. Sheffield, together with a
                            schedule identifying substantially identical agreements
                            between the Company and each of the other named executive
                            officers identified on Schedule I for the purpose of
                            defining the payment of certain benefits upon the
                            termination of the officer's employment under certain
                            circumstances (incorporated by reference to Exhibit 10.7
                            to the Company's Quarterly Report on Form 10-Q for the
                            period ended September 30, 1997, File No. 001-13245).
         10.49+          -- Indemnification Agreement, dated as of August 8, 1997,
                            between the Company and Scott D. Sheffield, together with
                            a schedule identifying substantially identical agreements
                            between the Company and each of the Company's other
                            directors and named executive officers identified on
                            Schedule I (incorporated by reference to Exhibit 10.8 to
                            the Company's Quarterly Report on Form 10-Q for the
                            period ended September 30, 1997, File No. 001-13245).
         10.50           -- Purchase and Sale Agreement, dated as of October 22,
                            1997, between Cometra Energy, L.P., and Pioneer USA
                            (incorporated by reference to Exhibit 10.22 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.51           -- Combination Agreement, dated September 3, 1997, between
                            the Company and Chauvco (incorporated by reference to
                            Exhibit 2.1 to the Company's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on October 2,
                            1997).
         10.52           -- Plan of Arrangement, as amended, under Section 186 of the
                            Business Corporations Act (Alberta) (incorporated by
                            reference to Exhibit 2.2 to the Company's Current Report
                            on Form 8-K, File No. 001-13245, filed with the SEC on
                            January 2, 1998).
</TABLE>
 
                                       113
<PAGE>   114
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.53           -- Support Agreement, dated as of December 18, 1997, between
                            the Company and Pioneer Canada (incorporated by reference
                            to Exhibit 2.3 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
         10.54           -- Stock Purchase Agreement, dated April 26, 1996, between
                            Mesa and DNR (incorporated by reference to Exhibit No. 10
                            to Mesa's Current Report on Form 8-K filed with the SEC
                            on April 29, 1996).
         10.55           -- "B" Contract Production Allocation Agreement, dated July
                            29, 1991, and effective as of January 1, 1991, between
                            Colorado Interstate Gas Company and Mesa Operating
                            Limited Partnership (incorporated by reference to Exhibit
                            10(r) to Mesa's Annual Report on Form 10-K for the period
                            ended December 31, 1991).
         10.56           -- Amendment to "B" Contract Production Allocation Agreement
                            effective as of January 1, 1993, between Colorado
                            Interstate Gas Company and Mesa Operating Limited
                            Partnership (incorporated by reference to Exhibit 10.24
                            to Mesa's Registration Statement on Form S-1,
                            Registration No. 33-51909).
         10.57           -- Amarillo Supply Agreement between Mesa Operating Limited
                            Partnership, Seller, and Energas Company, a division of
                            Atmos Energy Corporation, Buyer, dated effective January
                            2, 1993 (incorporated by reference to Exhibit 10.14 to
                            Mesa's Annual Report on Form 10-K for the period ended
                            December 31, 1995).
         10.58+          -- Agreement of Partnership of P&P Employees 89-B Conv.,
                            L.P. (formerly P&P Employees 89-B GP), dated October 31,
                            1989, among Parker & Parsley, Ltd. and the Investor
                            Partners (as defined therein, which includes individuals
                            who are directors and executive officers of Parker &
                            Parsley), together with a schedule identifying
                            substantially identical documents and setting forth the
                            material details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.50 to Parker & Parsley's Registration Statement on
                            Form S-4, dated December 31, 1990, Registration No.
                            33-38436).
         10.59+          -- Amendment to Agreement of Partnership of P&P Employees
                            89-B GP, dated May 31, 1990, among Parker & Parsley, Ltd.
                            and the Investor Partners (as defined therein, which
                            includes individuals who are directors and executives
                            officers of Parker & Parsley), together with a schedule
                            identifying substantially identical documents and setting
                            forth the material details in which those documents
                            differ form the foregoing document (incorporated by
                            reference to Exhibit 10.51 to Parker & Parsley's
                            Registration Statement on Form S-4, dated December 31,
                            1990, Registration No. 33-38436).
         10.60+          -- Schedule identifying additional documents substantially
                            identical to the Amendment to Agreement of Partnership of
                            P&P Employees 89-B GP included as Exhibit 10.59 and
                            setting forth the material details in which those
                            documents differ from that document (incorporated by
                            reference to Exhibit 10.52 to Parker & Parsley's
                            Registration Statement on Form S-1, dated February 28,
                            1992, Registration No. 33-46082).
</TABLE>
 
                                       114
<PAGE>   115
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.61+          -- Agreement of Partnership of P&P Employees 90 Spraberry
                            Private Development GP, dated October 16, 1990, among
                            Parker & Parsley, Ltd., James D. Moring, and the General
                            Partners (as defined therein, which includes individuals
                            who are directors and executive officers of Parker &
                            Parsley), and form of Amendment to Agreement of
                            Partnership of P&P Employees 90 Spraberry Private
                            Development GP, together with a schedule identifying
                            substantially identical documents and setting forth the
                            material details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.52 to Parker & Parsley's Registration Statement on
                            Form S-4, dated December 31, 1990, Registration No.
                            33-38436).
         10.62+          -- Amendment to Agreement of Partnership of Parker & Parsley
                            90-A GP, dated February 19, 1991, among Parker & Parsley
                            Development Company and the Investor Partners (as defined
                            therein, which includes individuals who are directors and
                            executive officers of Parker & Parsley), together with a
                            schedule identifying substantially identical documents
                            and setting forth the material details in which those
                            documents differ from the foregoing document
                            (incorporated by reference to Exhibit 10.58 to Parker &
                            Parsley's Registration Statement on Form S-1, dated
                            February 28, 1992, Registration No. 33-46082).
         10.63+          -- Agreement of Partnership of P&P Employees 91-A, GP, dated
                            September 30, 1991, among Parker & Parsley Development
                            Company, James D. Moring, and the General Partners (as
                            defined therein, which includes individuals who are
                            directors and executive officers of Parker & Parsley),
                            together with a schedule identifying substantially
                            identical documents and setting forth the material
                            details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.61 to Parker & Parsley's Registration Statement on
                            Form S-1, dated February 28, 1992, Registration No.
                            33-46082).
         10.64+          -- Amendment to Agreement of Partnership of P&P Employees 90
                            Spraberry Private Development GP, dated April 22, 1991,
                            among the Partners (as defined therein, which includes
                            individuals who are directors and executive officers of
                            Parker & Parsley) (incorporated by reference to Exhibit
                            10.67 to Parker & Parsley's Registration Statement on
                            Form S-1, dated February 28, 1992, Registration No.
                            33-46082).
         10.65           -- Share Purchase Agreement, dated February 13, 1998, among
                            the Company, Trimac Corporation and 761795 Alberta Ltd.
                            (incorporated by reference to Exhibit 99.1 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on February 23, 1998).
         10.66           -- Share Purchase Agreement, dated February 13, 1998, among
                            the Company, 398215 Alberta Ltd. and Guy J. Turcotte
                            (incorporated by reference to Exhibit 99.2 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on February 23, 1998).
         10.67           -- Option to Purchase Agreement, dated December 16, 1998, by
                            and among Costilla Energy, Inc. ("Costilla"), Pioneer
                            USA, and Pioneer Resources Producing, L.P. (incorporated
                            by reference to Exhibit 1 to the Company's statement on
                            Schedule 13D relating to the common stock of Costilla,
                            filed with the SEC on December 22, 1998, File No.
                            0-21411).
         10.68           -- Purchase and Sale Agreement, dated December 16, 1998, by
                            and among Costilla, Pioneer USA, and Pioneer Resources
                            Producing, L.P. (incorporated by reference to Exhibit 2
                            to the Company's statement on Schedule 13D relating to
                            the common stock of Costilla, filed with the SEC on
                            December 22, 1998, File No. 0-21411).
</TABLE>
 
                                       115
<PAGE>   116
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.69*          -- Second Amended and Restated Credit Facility Agreement
                            (Primary Facility) by and among Pioneer Natural Resources
                            Company, as Borrower, NationsBank, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guarantee Trust Company of New York, as
                            Documentation Agent, Chase Bank of Texas, National
                            Association, as Syndication Agent, The Co-Agents and
                            certain other lenders dated as of March 19, 1999.
         10.70*          -- Second Amended and Restated Credit Facility Agreement
                            (364 Day Facility) by and among Pioneer Natural Resources
                            Company, as Borrower, NationsBank, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guarantee Trust Company of New York, as
                            Documentation Agent, Chase Bank of Texas, National
                            Association, as Syndication Agent, The Co-Agents and
                            certain other lenders dated as of March 19, 1999.
         11.1*           -- Statement of Computation of Earnings per Share.
         21.1*           -- Subsidiaries of the registrant.
         23.1*           -- Consent of Ernst & Young LLP.
         23.2*           -- Consent of KPMG LLP.
         27.1*           -- Financial Data Schedule.
</TABLE>
 
- ---------------
 
* Filed herewith.
 
+ Executive Compensation Plan or Arrangement previously filed pursuant to Item
  14(c).
 
REPORTS ON FORM 8-K
 
     No reports on Form 8-K were filed by the Company during the fourth quarter
of 1998.
 
EXHIBITS
 
     The exhibits to this Report required to be filed pursuant to Item 14(c) are
listed under "Item 14. Exhibits, Financial Statement Schedules, and Reports on
Form 8-K -- Listing of Financial Statements and Exhibits -- Exhibits" above and
in the "Index to Exhibits" attached hereto.
 
FINANCIAL STATEMENT SCHEDULES
 
     No financial statement schedules are required to be filed as part of this
Report or are inapplicable.
 
                                       116
<PAGE>   117
 
                                   SIGNATURES
 
     Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.
 
                                          PIONEER NATURAL RESOURCES COMPANY
 
Date: March 23, 1999                      By:    /s/ SCOTT D. SHEFFIELD
                                            ------------------------------------
                                               Scott D. Sheffield, President
 
     Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated.
 
<TABLE>
<CAPTION>
                      SIGNATURE                                   TITLE                     DATE
                      ---------                                   -----                     ----
<C>                                                    <S>                           <C>
 
               /s/ SCOTT D. SHEFFIELD                  President, Chief Executive        March 23, 1999
- -----------------------------------------------------    Officer and Director
                 Scott D. Sheffield                      (principal executive
                                                         officer)
 
                /s/ M. GARRETT SMITH                   Executive Vice President and      March 23, 1999
- -----------------------------------------------------    Chief Financial Officer
                  M. Garrett Smith
 
                   /s/ RICH DEALY                      Vice President and Chief          March 23, 1999
- -----------------------------------------------------    Accounting Officer
                     Rich Dealy
 
                 /s/ I. JON BRUMLEY                    Chairman of the Board             March 23, 1999
- -----------------------------------------------------
                   I. Jon Brumley
 
                /s/ JAMES R. BAROFFIO                  Director                          March 23, 1999
- -----------------------------------------------------
                  James R. Baroffio
 
               /s/ R. HARTWELL GARDNER                 Director                          March 23, 1999
- -----------------------------------------------------
                 R. Hartwell Gardner
 
                /s/ KENNETH A. HERSH                   Director                          March 23, 1999
- -----------------------------------------------------
                  Kenneth A. Hersh
 
                /s/ JAMES L. HOUGHTON                  Director                          March 23, 1999
- -----------------------------------------------------
                  James L. Houghton
 
                 /s/ JERRY P. JONES                    Director                          March 23, 1999
- -----------------------------------------------------
                   Jerry P. Jones
 
              /s/ RICHARD E. RAINWATER                 Director                          March 23, 1999
- -----------------------------------------------------
                Richard E. Rainwater
 
             /s/ CHARLES E. RAMSEY, JR.                Director                          March 23, 1999
- -----------------------------------------------------
               Charles E. Ramsey, Jr.
 
                 /s/ PHILIP B. SMITH                   Director                          March 23, 1999
- -----------------------------------------------------
                   Philip B. Smith
 
               /s/ ROBERT L. STILLWELL                 Director                          March 23, 1999
- -----------------------------------------------------
                 Robert L. Stillwell
</TABLE>
 
                                       117
<PAGE>   118
 
                               INDEX TO EXHIBITS
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
          2.1            -- Amended and Restated Agreement and Plan of Merger, dated
                            as of April 6, 1997, by and among MESA Inc. ("Mesa"),
                            Mesa Operating Co. ("MOC"), MXP Reincorporation Corp. and
                            Parker & Parsley Petroleum Company ("Parker & Parsley")
                            (incorporated by reference to Exhibit 2.1 to the
                            Company's Registration Statement on Form S-4, dated June
                            27, 1997, Registration No. 333-26951).
          3.1            -- Amended and Restated Certificate of Incorporation of the
                            Company (incorporated by reference to Exhibit 3.1 to the
                            Company's Registration Statement on Form S-4, dated June
                            27, 1997, Registration No. 333-26951).
          3.2            -- Restated Bylaws of the Company (incorporated by reference
                            to Exhibit 3.2 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
          3.3            -- Certificate of Designations of Special Preferred Voting
                            Stock (incorporated by reference to Exhibit 3.3 of the
                            Company's Registration Statement on Form S-3,
                            Registration No. 333-42315, filed with the SEC on
                            December 17, 1997).
          3.4            -- Terms and Conditions of Exchangeable Shares (incorporated
                            by reference to Annex F to the Definitive Joint
                            Management Information Circular and Proxy Statement of
                            the Company and Chauvco Resources Ltd. ("Chauvco"), File
                            No. 001-13245, filed with the SEC on November 17, 1997).
          4.1            -- Form of Certificate of Common Stock, par value $.01 per
                            share, of the Company (incorporated by reference to
                            Exhibit 4.1 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
          4.2            -- Form of Certificate of Special Preferred Voting Stock
                            (incorporated by reference to Exhibit 4.1 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
          4.3            -- Form of Certificate of Exchangeable Shares (incorporated
                            by reference to Exhibit 4.2 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
          9.1            -- Voting and Exchange Trust Agreement, dated as of December
                            18, 1997, among the Company, Pioneer Natural Resources
                            (Canada) Ltd. ("Pioneer Canada") and Montreal Trust
                            Company of Canada, as Trustee (incorporated by reference
                            to Exhibit 2.4 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
          9.2            -- Amended and Restated Shareholders Agreement, dated as of
                            September 3, 1997, by and between the Company and Guy J.
                            Turcotte (incorporated by reference to Exhibit 2.6 to the
                            Company's Registration Statement on Form S-3,
                            Registration No. 333-42315, filed with the SEC on
                            December 15, 1997).
          9.3            -- Shareholders Agreement, dated as of September 3, 1997, by
                            and among the Company, Trimac Corporation and Gendis Inc.
                            (incorporated by reference to Exhibit 2.4 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on October 2, 1997).
         10.1            -- Indenture, dated July 2, 1996, among Pioneer USA
                            (formerly MOC), as Issuer, the Company, as Guarantor, and
                            Harris Trust and Savings Bank, as Trustee, relating to
                            the 11 5/8% Senior Subordinated Discount Notes due 2006
                            (incorporated by reference to Exhibit 4.17 to Mesa's
                            Quarterly Report on Form 10-Q for the period ended June
                            30, 1996).
</TABLE>
<PAGE>   119
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.2            -- First Supplemental Indenture, dated as of April 15, 1997,
                            among Pioneer USA (formerly MOC), as Issuer, Mesa, the
                            subsidiary guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.1 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.3            -- Second Supplemental Indenture, dated as of August 7,
                            1997, among Pioneer USA (formerly MOC), as Issuer, Mesa,
                            the subsidiary guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.2 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.4            -- Third Supplemental Indenture, dated as of December 18,
                            1997, among Pioneer USA, the Subsidiary Guarantors named
                            therein, the Company, and Harris Trust and Savings Bank,
                            as Trustee, with respect to the indenture identified
                            above as Exhibit 10.1 (incorporated by reference to
                            Exhibit 10.12 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
         10.5            -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA (formerly MOC), a Delaware
                            corporation, the Company, a Delaware corporation, Pioneer
                            NewSub1, Inc., a Texas corporation, and Harris Trust and
                            Savings Bank, an Illinois corporation, as Trustee, with
                            respect to the indenture identified above as Exhibit 10.1
                            (incorporated by reference to Exhibit 10.13 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.6            -- Fifth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer NewSub1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, the Company, a
                            Delaware corporation, Pioneer DebtCo., Inc., a Texas
                            corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.1 (incorporated
                            by reference to Exhibit 10.14 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.7            -- Sixth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo. Inc. (as successor to Pioneer
                            NewSub1, Inc.), a Texas corporation, the Company, a
                            Delaware corporation, and Harris Trust and Savings Bank,
                            an Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.1 (incorporated
                            by reference to Exhibit 10.15 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.8            -- Indenture, dated July 2, 1996, among Pioneer USA
                            (formerly MOC), as Issuer, the Company (Mesa's
                            successor), as Guarantor, and Harris Trust and Savings
                            Bank, as Trustee, relating to the 10 5/8% Senior
                            Subordinated Notes due 2006 (incorporated by reference to
                            Exhibit 4.18 to Mesa's Quarterly Report on Form 10-Q for
                            the period ended June 30, 1996).
         10.9            -- First Supplemental Indenture, dated as of April 15, 1997,
                            among Pioneer USA (formerly MOC), as Issuer, Mesa, the
                            Subsidiary Guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.8
                            (incorporated by reference to Exhibit 10.3 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
</TABLE>
<PAGE>   120
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.10           -- Second Supplemental Indenture, dated as of August 7,
                            1997, among Pioneer USA (formerly MOC), as Issuer, Mesa,
                            the Subsidiary Guarantors named therein, the Company, and
                            Harris Trust and Savings Bank, as Trustee, with respect
                            to the indenture identified above as Exhibit 10.8
                            (incorporated by reference to Exhibit 10.4 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.11           -- Third Supplemental Indenture, dated as of December 18,
                            1997, among Pioneer USA, the Subsidiary Guarantors named
                            therein, the Company, and Harris Trust and Savings Bank,
                            as Trustee, with respect to the indenture identified
                            above as Exhibit 10.8 (incorporated by reference to
                            Exhibit 10.6 to the Company's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 2,
                            1998).
         10.12           -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA, a Delaware corporation, the
                            Company, a Delaware corporation, Pioneer NewSub1, Inc., a
                            Texas corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.7 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.13           -- Fifth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer NewSub1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, the Company, a
                            Delaware corporation, Pioneer DebtCo., Inc., a Texas
                            corporation, and Harris Trust and Savings Bank, an
                            Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.8 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.14           -- Sixth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo, Inc. (as successor to Pioneer
                            NewSub1, Inc.), a Texas corporation, the Company, a
                            Delaware corporation, and Harris Trust and Savings Bank,
                            an Illinois corporation, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.8 (incorporated
                            by reference to Exhibit 10.9 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.15           -- Indenture, dated April 12, 1995, between Pioneer USA
                            (successor to Parker & Parsley), and The Chase Manhattan
                            Bank (National Association), as Trustee (incorporated by
                            reference to Exhibit 4.1 to Parker & Parsley's Current
                            Report on Form 8-K, dated April 12, 1995, File No.
                            001-10695).
         10.16           -- First Supplemental Indenture, dated as of August 7, 1997,
                            among Parker & Parsley, The Chase Manhattan Bank, as
                            Trustee, and Pioneer USA, with respect to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 10.5 to the Company's Quarterly
                            Report on Form 10-Q for the period ended September 30,
                            1997, File No. 001-13245).
         10.17           -- Second Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer USA, a Delaware corporation, Pioneer
                            NewSub1, Inc., a Texas corporation, and The Chase
                            Manhattan Bank, a New York banking association, as
                            Trustee, with respect to the indenture identified above
                            as Exhibit 10.15 (incorporated by reference to Exhibit
                            10.17 to the Company's Current Report on Form 8-K, File
                            No. 001-13245, filed with the SEC on January 2, 1998).
</TABLE>
<PAGE>   121
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.18           -- Third Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer NewSub1, Inc. (as successor to
                            Pioneer USA), a Texas corporation, Pioneer DebtCo, Inc.,
                            a Texas corporation, and The Chase Manhattan Bank, a New
                            York banking association, as Trustee, with respect to the
                            indenture identified above as Exhibit 10.15 (incorporated
                            by reference to Exhibit 10.18 to the Company's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 2, 1998).
         10.19           -- Fourth Supplemental Indenture, dated as of December 30,
                            1997, among Pioneer DebtCo, Inc. (as successor to Pioneer
                            NewSub1, Inc., as successor to Pioneer USA), a Texas
                            corporation, the Company, a Delaware corporation, Pioneer
                            USA, a Delaware corporation, and The Chase Manhattan
                            Bank, a New York banking association, as Trustee, with
                            respect to the indenture identified above as Exhibit
                            10.15 (incorporated by reference to Exhibit 10.19 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.20           -- Guarantee, dated as of December 30, 1997, by Pioneer USA
                            relating to the $150,000,000 in aggregate principal
                            amount of 8 7/8% Senior Notes due 2005 and $150,000,000
                            in aggregate principal amount of 8 1/4% Senior Notes due
                            2007 issued under the indenture identified above as
                            Exhibit 10.15 (incorporated by reference to Exhibit 10.20
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
         10.21           -- Form of 8 7/8% Senior Notes due 2005, dated as of April
                            12, 1995, in the aggregate principal amount of
                            $150,000,000, together with Officers' Certificate dated
                            April 12, 1995, establishing the terms of the 8 7/8%
                            Senior Notes due 2005 pursuant to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 4.2 to Parker & Parsley's Quarterly
                            Report on Form 10-Q for the period ended June 30, 1995,
                            File No. 001-10695).
         10.22           -- Form of 8 1/4% Senior Notes due 2007, dated as of August
                            22, 1995, in the aggregate principal amount of
                            $150,000,000, together with Officers' Certificate dated
                            August 22, 1995, establishing the terms of the 8 1/4%
                            Senior Notes due 2007 pursuant to the indenture
                            identified above as Exhibit 10.15 (incorporated by
                            reference to Exhibit 1.2 to Parker & Parsley's Current
                            Report on Form 8-K, dated August 17, 1995, File No.
                            001-10695).
         10.23           -- Indenture, dated January 13, 1998, between the Company
                            and The Bank of New York, as Trustee (incorporated by
                            reference to Exhibit 99.1 to the Company's and Pioneer
                            USA's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 14, 1998).
         10.24           -- First Supplemental Indenture, dated as of January 13,
                            1998, among the Company, Pioneer USA, as the Subsidiary
                            Guarantor, and The Bank of New York, as Trustee, with
                            respect to the indenture identified above as Exhibit
                            10.23 (incorporated by reference to Exhibit 99.2 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
         10.25           -- Form of 6.50% Senior Notes due 2008 of the Company
                            (incorporated by reference to Exhibit 99.3 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
         10.26           -- Form of 7.20% Senior Notes due 2028 of the Company
                            (incorporated by reference to Exhibit 99.4 to the
                            Company's and Pioneer USA's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on January 14,
                            1998).
</TABLE>
<PAGE>   122
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.27           -- Guarantee (2008 Notes), dated as of January 13, 1998,
                            entered into by Pioneer USA (incorporated by reference to
                            Exhibit 99.5 to the Company's and Pioneer USA's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 14, 1998).
         10.28           -- Guarantee (2028 Notes), dated as of January 13, 1998,
                            entered into by Pioneer USA (incorporated by reference to
                            Exhibit 99.6 to the Company's and Pioneer USA's Current
                            Report on Form 8-K, File No. 001-13245, filed with the
                            SEC on January 14, 1998).
         10.29           -- Amended and Restated Credit Facility Agreement (Primary
                            Facility), dated as of December 18, 1997, between the
                            Company, as Borrower, and NationsBank of Texas, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, and The Chase Manhattan Bank, as
                            Syndication Agent; and the other Co-Agents and lenders
                            named therein (incorporated by reference to Exhibit 10.1
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
         10.30*          -- First Amendment to Amended and Restated Credit Facility
                            Agreement (Primary Facility), dated as of June 29, 1998,
                            by and among the Company, as Borrower, NationsBank, N.A.,
                            as Administrative Agent, CIBC Inc., as Documentation
                            Agent, Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, The Chase Manhattan Bank, as
                            Syndication Agent, and the Co-Agents and other Lenders
                            signatory thereto.
         10.31           -- Amended and Restated Credit Facility Agreement (364 Day
                            Facility), dated as of December 18, 1997, between the
                            Company, as Borrower, and NationsBank of Texas, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, and The Chase Manhattan Bank, as
                            Syndication Agent; and the other Co-Agents and lenders
                            named therein (incorporated by reference to Exhibit 10.2
                            to the Company's Current Report on Form 8-K, File No.
                            001-13245, filed with the SEC on January 2, 1998).
         10.32*          -- First Amendment to Amended and Restated Credit Facility
                            Agreement (364 Day Facility), dated as of June 29, 1998,
                            by and among the Company, as Borrower, NationsBank, N.A.,
                            as Administrative Agent, CIBC Inc., as Documentation
                            Agent, Morgan Guaranty Trust Company of New York, as
                            Documentation Agent, The Chase Manhattan Bank, as
                            Syndication Agent, and the Co-Agents and other lenders
                            signatory thereto.
         10.33           -- Credit Agreement, dated as of December 18, 1997, among
                            Chauvco, Canadian Imperial Bank of Commerce, as Agent,
                            and the other lenders named therein (incorporated by
                            reference to Exhibit 10.3 to the Company's Current Report
                            on Form 8-K, File No. 001-13245, filed with the SEC on
                            January 2, 1998).
         10.34*          -- First Amending Agreement, dated June 29, 1998, among
                            Pioneer Natural Resources Canada Inc. (formerly Chauvco),
                            Canadian Imperial Bank of Commerce, and the lenders
                            thereto, with respect to the Credit Agreement identified
                            above as Exhibit 10.33.
         10.35           -- Note, dated December 22, 1997, between the Company, as
                            Borrower, and NationsBank of Texas, N.A., as lender
                            (incorporated by reference to Exhibit 10.21 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
</TABLE>
<PAGE>   123
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.36+          -- 1991 Stock Option Plan of Mesa (incorporated by reference
                            to Exhibit 10(v) to Mesa's Annual Report on Form 10-K for
                            the period ended December 31, 1991).
         10.37+          -- 1996 Incentive Plan of Mesa (incorporated by reference to
                            Exhibit 10.28 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
         10.38+          -- Parker & Parsley Long-Term Incentive Plan, dated February
                            19, 1991 (incorporated by reference to Exhibit 4.1 to
                            Parker & Parsley's Registration Statement on Form S-8,
                            Registration No. 33-38971).
         10.39+          -- First Amendment to the Parker & Parsley Long-Term
                            Incentive Plan, dated August 23, 1991 (incorporated by
                            reference to Exhibit 10.2 to Parker & Parsley's
                            Registration Statement on Form S-1, dated February 28,
                            1992, Registration No. 33-46082).
         10.40+          -- The Company's Long-Term Incentive Plan (incorporated by
                            reference to Exhibit 4.1 to the Company's Registration
                            Statement on Form S-8, Registration No. 333-35087).
         10.41+          -- The Company's Employee Stock Purchase Plan (incorporated
                            by reference to Exhibit 4.1 to the Company's Registration
                            Statement on Form S-8, Registration No. 333-35165).
         10.42*          -- Amendment No. 1 to the Company's Employee Stock Purchase
                            Plan, dated December 9, 1998.
         10.43+          -- The Company's Deferred Compensation Retirement Plan
                            (incorporated by reference to Exhibit 4.1 to the
                            Company's Registration Statement on Form S-8,
                            Registration No. 333-39153).
         10.44+          -- Pioneer USA 401(k) Plan (incorporated by reference to
                            Exhibit 4.1 to the Company's Registration Statement on
                            Form S-8, Registration No. 333-39249).
         10.45+          -- Pioneer USA Matching Plan (incorporated by reference to
                            Exhibit 10.42 to the Company's Annual Report on Form 10-K
                            for the year ended December 31, 1997, File No.
                            001-13245).
         10.46+          -- Omnibus Amendment to Nonstatutory Stock Option
                            Agreements, included as part of the Parker & Parsley
                            Long-Term Incentive Plan, dated as of November 16, 1995,
                            between Parker & Parsley and Named Executive Officers
                            identified on Schedule 1 setting forth additional details
                            relating to the Parker & Parsley Long-Term Incentive Plan
                            (incorporated by reference to Parker & Parsley's Annual
                            Report on Form 10-K for the year ended December 31, 1995,
                            File No. 001-10695).
         10.47+          -- Mesa Management Severance Plan, dated April 4, 1997,
                            including a Schedule of Participants on Schedule A for
                            the purpose of defining the payment of certain benefits
                            upon the termination of the officer's employment under
                            certain circumstances (incorporated by reference to
                            Exhibit 10.29 to the Company's Registration Statement on
                            Form S-4, dated June 27, 1997, Registration No.
                            333-26951).
         10.48+          -- Severance Agreement, dated as of August 8, 1997, between
                            the Company and Scott D. Sheffield, together with a
                            schedule identifying substantially identical agreements
                            between the Company and each of the other named executive
                            officers identified on Schedule I for the purpose of
                            defining the payment of certain benefits upon the
                            termination of the officer's employment under certain
                            circumstances (incorporated by reference to Exhibit 10.7
                            to the Company's Quarterly Report on Form 10-Q for the
                            period ended September 30, 1997, File No. 001-13245).
</TABLE>
<PAGE>   124
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.49+          -- Indemnification Agreement, dated as of August 8, 1997,
                            between the Company and Scott D. Sheffield, together with
                            a schedule identifying substantially identical agreements
                            the Company and each of the Company's other directors and
                            named executive officers identified on Schedule I
                            (incorporated by reference to Exhibit 10.8 to the
                            Company's Quarterly Report on Form 10-Q for the period
                            ended September 30, 1997, File No. 001-13245).
         10.50           -- Purchase and Sale Agreement, dated as of October 22,
                            1997, between Cometra Energy, L.P., and Pioneer USA
                            (incorporated by reference to Exhibit 10.22 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on January 2, 1998).
         10.51           -- Combination Agreement, dated September 3, 1997, between
                            the Company and Chauvco (incorporated by reference to
                            Exhibit 2.1 to the Company's Current Report on Form 8-K,
                            File No. 001-13245, filed with the SEC on October 2,
                            1997).
         10.52           -- Plan of Arrangement, as amended, under Section 186 of the
                            Business Corporations Act (Alberta) (incorporated by
                            reference to Exhibit 2.2 to the Company's Current Report
                            on Form 8-K, File No. 001-13245, filed with the SEC on
                            January 2, 1998).
         10.53           -- Support Agreement, dated as of December 18, 1997, between
                            the Company and Pioneer Canada (incorporated by reference
                            to Exhibit 2.3 to the Company's Current Report on Form
                            8-K, File No. 001-13245, filed with the SEC on January 2,
                            1998).
         10.54           -- Stock Purchase Agreement, dated April 26, 1996, between
                            Mesa and DNR (incorporated by reference to Exhibit No. 10
                            to Mesa's Current Report on Form 8-K filed with the SEC
                            on April 29, 1996).
         10.55           -- "B" Contract Production Allocation Agreement, dated July
                            29, 1991, and effective as of January 1, 1991, between
                            Colorado Interstate Gas Company and Mesa Operating
                            Limited Partnership (incorporated by reference to Exhibit
                            10(r) to Mesa's Annual Report on Form 10-K for the period
                            ended December 31, 1991).
         10.56           -- Amendment to "B" Contract Production Allocation Agreement
                            effective as of January 1, 1993, between Colorado
                            Interstate Gas Company and Mesa Operating Limited
                            Partnership (incorporated by reference to Exhibit 10.24
                            to Mesa's Registration Statement on Form S-1,
                            Registration No. 33-51909).
         10.57           -- Amarillo Supply Agreement between Mesa Operating Limited
                            Partnership, Seller, and Energas Company, a division of
                            Atmos Energy Corporation, Buyer, dated effective January
                            2, 1993 (incorporated by reference to Exhibit 10.14 to
                            Mesa's Annual Report on Form 10-K for the period ended
                            December 31, 1995).
         10.58+          -- Agreement of Partnership of P&P Employees 89-B Conv.,
                            L.P. (formerly P&P Employees 89-B GP), dated October 31,
                            1989, among Parker & Parsley, Ltd. and the Investor
                            Partners (as defined therein, which includes individuals
                            who are directors and executive officers of Parker &
                            Parsley), together with a schedule identifying
                            substantially identical documents and setting forth the
                            material details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.50 to Parker & Parsley's Registration Statement on
                            Form S-4, dated December 31, 1990, Registration No.
                            33-38436).
</TABLE>
<PAGE>   125
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.59+          -- Amendment to Agreement of Partnership of P&P Employees
                            89-B GP, dated May 31, 1990, among Parker & Parsley, Ltd.
                            and the Investor Partners (as defined therein, which
                            includes individuals who are directors and executive
                            officers of Parker & Parsley), together with a schedule
                            identifying substantially identical documents and setting
                            forth the material details in which those documents
                            differ from the foregoing document (incorporated by
                            reference to Exhibit 10.51 to Parker & Parsley's
                            Registration Statement on Form S-4, dated December 31,
                            1990, Registration No. 33-38436).
         10.60+          -- Schedule identifying additional documents substantially
                            identical to the Amendment to Agreement of Partnership of
                            P&P Employees 89-B GP included as Exhibit 10.59 and
                            setting forth the material details in which those
                            documents differ from that document (incorporated by
                            reference to Exhibit 10.52 to Parker & Parsley's
                            Registration Statement on Form S-1, dated February 28,
                            1992, Registration No. 33-46082).
         10.61+          -- Agreement of Partnership of P&P Employees 90 Spraberry
                            Private Development GP, dated October 16, 1990, among
                            Parker & Parsley, Ltd., James D. Moring, and the General
                            Partners (as defined therein, which includes individuals
                            who are directors and executive officers of Parker &
                            Parsley), and form of Amendment to Agreement of
                            Partnership of P&P Employees 90 Spraberry Private
                            Development GP, together with a schedule identifying
                            substantially identical documents and setting forth the
                            material details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.52 to Parker & Parsley's Registration Statement on
                            Form S-4, dated December 31, 1990, Registration No.
                            33-38436).
         10.62+          -- Amendment to Agreement of Partnership of Parker & Parsley
                            90-A GP, dated February 19, 1991, among Parker & Parsley
                            Development Company and the Investor Partners (as defined
                            therein, which includes individuals who are directors and
                            executive officers of Parker & Parsley), together with a
                            schedule identifying substantially identical documents
                            and setting forth the material details in which those
                            documents differ from the foregoing document
                            (incorporated by reference to Exhibit 10.58 to Parker &
                            Parsley's Registration Statement on Form S-1, dated
                            February 28, 1992, Registration No. 33-46082).
         10.63+          -- Agreement of Partnership of P&P Employees 91-A, GP, dated
                            September 30, 1991, among Parker & Parsley Development
                            Company, James D. Moring, and the General Partners (as
                            defined therein, which includes individuals who are
                            directors and executive officers of Parker & Parsley),
                            together with a schedule identifying substantially
                            identical documents and setting forth the material
                            details in which those documents differ from the
                            foregoing document (incorporated by reference to Exhibit
                            10.61 to Parker & Parsley's Registration Statement on
                            Form S-1, dated February 28, 1992, Registration No.
                            33-46082).
         10.64+          -- Amendment to Agreement of Partnership of P&P Employees 90
                            Spraberry Private Development GP, dated April 22, 1991,
                            among the Partners (as defined therein, which includes
                            individuals who are directors and executive officers of
                            Parker & Parsley) (incorporated by reference to Exhibit
                            10.67 to Parker & Parsley's Registration Statement on
                            Form S-1, dated February 28, 1992, Registration No.
                            33-46082).
</TABLE>
<PAGE>   126
 
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
         10.65           -- Share Purchase Agreement, dated February 13, 1998, among
                            the Company, Trimac Corporation and 761795 Alberta Ltd.
                            (incorporated by reference to Exhibit 99.1 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on February 23, 1998).
         10.66           -- Share Purchase Agreement, dated February 13, 1998, among
                            the Company, 398215 Alberta Ltd. and Guy J. Turcotte
                            (incorporated by reference to Exhibit 99.2 to the
                            Company's Current Report on Form 8-K, File No. 001-13245,
                            filed with the SEC on February 23, 1998).
         10.67           -- Option to Purchase Agreement, dated December 16, 1998, by
                            and among Costilla Energy, Inc. ("Costilla"), Pioneer
                            USA, and Pioneer Resources Producing, L.P. (incorporated
                            by reference to Exhibit 1 to the Company's statement on
                            Schedule 13D relating to the common stock of Costilla,
                            filed with the SEC on December 22, 1998, File No.
                            0-21411).
         10.68           -- Purchase and Sale Agreement, dated December 16, 1998, by
                            and among Costilla, Pioneer USA, and Pioneer Resources
                            Producing, L.P. (incorporated by reference to Exhibit 2
                            to the Company's statement on Schedule 13D relating to
                            the common stock of Costilla, filed with the SEC on
                            December 22, 1998, File No. 0-21411).
         10.69*          -- Second Amended and Restated Credit Facility Agreement
                            (Primary Facility) by and among Pioneer Natural Resources
                            Company, as Borrower, NationsBank, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guarantee Trust Company of New York, as
                            Documentation Agent, Chase Bank of Texas, National
                            Association, as Syndication Agent, The Co-Agents and
                            certain other lenders dated as of March 19, 1999.
         10.70*          -- Second Amended and Restated Credit Facility Agreement
                            (364 Day Facility) by and among Pioneer Natural Resources
                            Company, as Borrower, NationsBank, N.A., as
                            Administrative Agent, CIBC Inc., as Documentation Agent,
                            Morgan Guarantee Trust Company of New York, as
                            Documentation Agent, Chase Bank of Texas, National
                            Association, as Syndication Agent, The Co-Agents and
                            certain other lenders dated as of March 19, 1999.
         11.1*           -- Statement of Computation of Earnings per Share.
         21.1*           -- Subsidiaries of the registrant.
         23.1*           -- Consent of Ernst & Young LLP.
         23.2*           -- Consent of KPMG LLP.
         27.1*           -- Financial Data Schedule.
</TABLE>
 
- ---------------
 
* Filed herewith.
 
+ Executive Compensation Plan or Arrangement previously filed pursuant to Item
  14(c).

<PAGE>   1

                                                                   EXHIBIT 10.30

                            [PRIMARY CREDIT FACILITY]

================================================================================

                               FIRST AMENDMENT TO
                 AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

                                  by and among

                       PIONEER NATURAL RESOURCES COMPANY,
                                  as Borrower,

                                       and

                               NATIONSBANK, N.A.,
                            as Administrative Agent,

                                       and

                                   CIBC INC.,
                             as Documentation Agent,

                                       and

                   MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                             as Documentation Agent,

                                       and

                            THE CHASE MANHATTAN BANK,
                              as Syndication Agent,

                         THE CO-AGENTS SIGNATORY HERETO,

                                       and

                       THE OTHER LENDERS SIGNATORY HERETO


                            Dated as of June 29, 1998

================================================================================


<PAGE>   2


                               FIRST AMENDMENT TO
                 AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

         THIS FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT FACILITY AGREEMENT
(herein called this "Amendment"), is made as of June 29, 1998, by and among
PIONEER NATURAL RESOURCES COMPANY, a Delaware corporation (the "Borrower"),
NATIONSBANK, N.A., as successor-by-merger to NationsBank of Texas, N.A., as
Administrative Agent and Collateral Agent, CIBC INC., as Documentation Agent,
MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation Agent, THE CHASE
MANHATTAN BANK, as Syndication Agent, the "Co-Agents" party to the Credit
Agreement (as herein defined), and the other Lenders from time to time parties
to the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents have heretofore entered into a certain Amended and
Restated Credit Facility Agreement - Primary Credit Facility, dated as of 
December 18, 1997 (herein the "Credit Agreement"); and

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents now intend to amend the Credit Agreement in certain
respects; and

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained , each of the Borrower, the Lenders, the Managing
Agents, the Collateral Agent and the Co-Agents hereby agree as follows:

         SECTION 1. Defined Terms. All capitalized terms used but not otherwise
defined herein shall have the meanings given in the Credit Agreement.

         SECTION 2.  Amendments to Credit Agreement

         a.            The Credit Agreement is hereby amended by modifying each
                  reference therein to "NationsBank of Texas, N.A." to read
                  "NationsBank, N.A., successor-by-merger to NationsBank of
                  Texas, N.A."

         b.            The definitions of "Amendment Fee Rate" and "Eurodollar
                  Margin" in Section 1.1 of the Credit Agreement are hereby
                  amended and restated to read in their entirety as follows:

         "        "Amendment Fee Rate" means 15.0 basis points."

         "        "Eurodollar Margin" means, on any date, with respect to each
         Eurodollar Portion of a Revolving Loan, the sum of (i) the applicable
         Commitment Utilization Margin plus (ii) the number of basis points per
         annum set forth below based on the Applicable Rating Level on such
         date:


<PAGE>   3


<TABLE>
<CAPTION>
=========================================================
        Applicable
       Rating Level
- ---------------------------------------------------------
<S>                                     <C>      
         Level I                        18.0 b.p.
- ---------------------------------------------------------
         Level II                       20.0 b.p.
- ---------------------------------------------------------
         Level III                      23.0 b.p.
- ---------------------------------------------------------
         Level IV                       36.0 b.p.
- ---------------------------------------------------------
         Level V                        45.0 b.p.
=========================================================
</TABLE>

         Changes in the Eurodollar Margin will occur automatically without prior
         notice. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Eurodollar Margin."

         c.            Section 1.1 of the Credit Agreement is hereby amended by
                  inserting the following definitions of "Commitment
                  Utilization", "Commitment Utilization Level", "Commitment
                  Utilization Margin", "Year 2000 Compliant" and "Year 2000
                  Problem" in appropriate alphabetical order:

         "        "Commitment Utilization" means, for any period, the ratio of 
         (i) the aggregate amount of then outstanding Loans plus then existing 
         LC Obligations to (ii) the current Facility Amount."

         "        "Commitment Utilization Level" means the level set forth below
         that corresponds to the lowest of the ratings issued from time to time 
         by Moody's and S&P, as applicable, for Borrower's senior unsecured
         long-term debt:

<TABLE>
<CAPTION>
========================================================================
                                Moody's                 S&P
- ------------------------------------------------------------------------
<S>                          <C>                   <C>           
Level A                      Baa3 or better        BBB- or better
- ------------------------------------------------------------------------
Level B                      Less than Baa3        Less than BBB-
========================================================================
</TABLE>

         For example, if the Moody's rating is Ba1 and the S&P rating is BBB,
         Level B shall apply. For purposes of the foregoing, (i) if ratings for
         Borrower's senior unsecured long-term debt shall not be available from
         S&P or Moody's, Level B shall be deemed applicable; and (ii) if any of
         the Rating Agencies shall change its ratings nomenclature prior to the
         date all Obligations have been paid and the Commitments canceled,
         Borrower and the Lenders shall negotiate in good faith to amend the
         references to specific ratings in this definition to reflect such
         change, and pending such amendment, if an appropriate Commitment
         Utilization Level is otherwise not determinable based upon the
         foregoing grid, the last Commitment Utilization Level in effect at the
         time of such change shall continue to apply."



                                        2

<PAGE>   4


         " "Commitment Utilization Margin" means, on any date, the number of
         basis points per annum set forth below based on the Commitment
         Utilization Level on such date:

<TABLE>
<CAPTION>
================================================================================
                               Commitment Utilization Margin
- --------------------------------------------------------------------------------
                                   Commitment                 Commitment
     Commitment                  Utilization is              Utilization is
  Utilization Level            "< or equal to .50"               ">.50"
- --------------------------------------------------------------------------------
<S>                            <C>                           <C>     
       Level A                        0 b.p.                    5.0 b.p.
- --------------------------------------------------------------------------------
       Level B                        0 b.p.                   10.0 b.p.
================================================================================
</TABLE>

         ; provided, however, for the purpose of determining the Commitment
         Utilization Margin for all periods ending prior to or on June 30, 1999,
         the Commitment Utilization of Borrower shall be deemed to be greater
         than ".50". Changes in the Commitment Utilization Margin will occur
         automatically without prior notice."

         "        "Year 2000 Compliant" has the meaning given it in Section
         4.1(s)."

         "        "Year 2000 Problem" has the meaning given it in Section 
         4.1(s)."

         d.            Section 4.1 of the Credit Agreement is hereby amended by
                  inserting the following Section 4.1(s) after Section 4.1(r):

         "(s)     Year 2000 Compliance. Borrower has (i) initiated a review
                  and assessment of all areas within its and each of its
                  Subsidiaries' business and operations (including those
                  affected by suppliers and vendors) that could be adversely
                  affected by the Year 2000 Problem (as herein defined), (ii)
                  developed a plan and time line for addressing the Year 2000
                  Problem on a timely basis, and (iii) to date, implemented that
                  plan in accordance with that timetable. Borrower reasonably
                  believes that all computer applications (including those of
                  its suppliers and vendors) that are material to its or any of
                  its Subsidiaries' business and operations will be Year 2000
                  Compliant, except to the extent that a failure to do so could
                  not reasonably be expected to have Material Adverse Effect. As
                  used herein, the term "Year 2000 Problem" means the risk that
                  computer applications used by the Borrower or any of its
                  Subsidiaries (or its suppliers and vendors) may be unable to
                  recognize and perform properly date- sensitive functions
                  involving certain dates prior to and any date after December
                  31, 1999. As used herein, the term "Year 2000 Compliant" means
                  that all computer applications will on a timely basis be able
                  to perform properly date-sensitive functions for all dates
                  before and after January 1, 2000."

         e.            Section 5.1 of the Credit Agreement is hereby amended by
                  inserting the following Section 5.1(m) after Section 5.1(l):


                                       3
<PAGE>   5


         "(m)     Year 2000 Compliance. Borrower will promptly notify
                  Administrative Agent in the event Borrower discovers or
                  determines that any computer application (including those of
                  its suppliers and vendors) that is material to its or any of
                  its Subsidiaries' business and operations will not be Year
                  2000 Compliant on a timely basis, except to the extent that
                  such failure could not reasonably be expected to have a
                  Material Adverse Effect."

         f.            Section 5.3(a) of the Credit Agreement is hereby amended 
                  and restated to read in its entirety as follows:

                  "(a) EBITDAX to Consolidated Interest Expense Ratio. The ratio
         of Borrower's "EBITDAX" to "Consolidated Interest Expense" for the last
         four rolling Fiscal Quarters (i) ending June 30, 1998 and September 30,
         1998, will not be less than 2.50 to 1.0, (ii) ending December 31, 1998,
         will not be less than 2.75 to 1.0, (iii) ending March 31, 1999, will
         not be less than 3.00 to 1.0, (iv) ending June 30, 1999, will not be
         less than 3.25 to 1.0, and (v) ending after June 30, 1999, will not be
         less than 3.75 to 1.0; provided, however, that for the periods for
         calculation ending on or before December 31, 1998, each reference to
         "for the last four rolling Fiscal Quarters" shall be deemed to be a
         reference to the period from April 1, 1998 through the date of such
         calculation. As used in this paragraph, the term "Consolidated Interest
         Expense" means for any period, total interest expense, whether paid or
         accrued, of Borrower and its Subsidiaries on a Consolidated basis,
         including, without limitation, all commissions, discounts and other
         fees and charges owed with respect to Letters of Credit. As used in
         this paragraph, the term "EBITDAX" means for any period the sum of the
         amounts for such period of Consolidated net income, Consolidated
         Interest Expense, depreciation expense, depletion expense, amortization
         expense, federal and state income taxes, exploration and abandonment
         expense and other non-cash charges and expenses, all as determined on a
         Consolidated basis for Borrower and its Subsidiaries."

         g.            Section 5.3(b) of the Credit Agreement is hereby amended 
                  and restated to read in its entirety as follows:

                  "(b) Consolidated Total Funded Debt to Total Capitalization.
         Borrower's Consolidated Total Funded Debt to Total Capitalization will
         not (i) as of the last day of the Fiscal Quarters ending June 30, 1998
         and September 30, 1998, be greater than 62.5%, and (ii) as of the last
         day of any Fiscal Quarter ending after September 30, 1998, be greater
         than 60%."

         h.            The fourth sentence of Section 8.17 of the Credit 
                  Agreement is hereby amended and restated to read in its 
                  entirety as follows:

         "FOR THE PURPOSE OF ANY ACTION OR PROCEEDING INSTITUTED IN THE FEDERAL
         OR STATE COURTS OF TEXAS, EACH RESTRICTED SUBSIDIARY OF THE BORROWER
         HEREBY IRREVOCABLY DESIGNATES BORROWER WITH OFFICES ON THE DATE HEREOF
         AT 1400 WILLIAMS 



                                       4
<PAGE>   6

         SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD, IRVING, TEXAS 75039 TO
         RECEIVE FOR AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY, SERVICES OF
         PROCESS IN TEXAS."

         i.            The Credit Agreement is hereby amended by replacing 
                  Exhibit J to the Credit Agreement with Exhibit J to this 
                  Amendment.

         j.            Schedule 3 attached to the Credit Agreement is hereby 
                  amended by deleting therefrom the reference to "Pioneer 
                  Natural Resources (GPC) Inc., a Delaware corporation".

         SECTION 3. Representations and Warranties. To confirm each Lender's
understanding concerning Borrower and its businesses, properties and
obligations, and to induce the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender to enter into this Amendment, the Borrower hereby
reaffirms to the Managing Agents, the Collateral Agent, the Co-Agents and each
Lender that, as of the date hereof, its representations and warranties contained
in Section 4.1 of the Credit Agreement (as amended by this Amendment) and in the
other Loan Documents to which it is a party (except to the extent such
representations and warranties relate solely to an earlier date) are true and
correct and additionally represents and warrants as follows:

A.       The execution and delivery of this Amendment and the performance by the
         Borrower and the Restricted Subsidiaries of their respective
         obligations under this Amendment, the Credit Agreement and the other
         Loan Documents, as amended hereby, are within the Borrower's or such
         Restricted Subsidiaries' corporate or partnership powers, have been
         duly authorized by all necessary corporate or partnership action, have
         received all necessary governmental approval (if any shall be
         required), and do not and will not contravene or conflict with any
         provision of law or of the Borrower's or such Restricted Subsidiaries'
         charter or bylaws or partnership agreement or of any contractual
         restriction, law or governmental regulation or court decree or order
         binding on or affecting the Borrower or such Restricted Subsidiary.

B.       This Amendment and the Credit Agreement as amended hereby are, and the
         other Loan Documents when duly executed and delivered will be, legal,
         valid and binding obligations of the Borrower and each Restricted
         Subsidiary which is a party hereto or thereto, enforceable in
         accordance with their terms except as such enforcement may be limited
         by bankruptcy, insolvency or similar laws of general application
         relating to the enforcement of creditors' rights generally and by
         general principles of equity.

         SECTION 4. Conditions to Effectiveness. The effectiveness of this
Amendment is conditioned upon receipt by the Administrative Agent of all the
following documents and items, each in form and substance reasonably
satisfactory to the Administrative Agent:

A.       this Amendment executed by the Borrower and the Required Lenders.

B.       Borrower will pay, or cause the payment, to Administrative Agent for
         the account of each Lender a non-refundable amendment fee payable to
         each Lender determined by applying the


                                       5
<PAGE>   7

         Amendment Fee Rate to such Lender's Percentage Share of the Facility
         Amount as of the date of this Amendment.

C.       Such other documents or items that the Administrative Agent may
         reasonably request.

         SECTION 5. Reaffirmation of Credit Agreement. This Amendment
constitutes a "Loan Document" as defined in the Credit Agreement and shall be
deemed to be an amendment to the Credit Agreement, and the Credit Agreement, as
amended hereby, is hereby ratified, approved and confirmed in each and every
respect. All references to the Credit Agreement or the Credit Facility Agreement
in any other document, instrument, agreement or writing shall hereafter be
deemed to refer to the Credit Agreement as amended hereby.

         SECTION 6. Parties in Interest. All grants, covenants and agreements
contained in this Amendment shall bind and inure to the benefit of the parties
thereto and their respective successors and assigns; provided, however, that no
Restricted Subsidiary may assign or transfer any of its rights or delegate any
of its duties or obligations under this Amendment or any Loan Document without
the prior written consent of all Lenders.

         SECTION 7. Counterparts. This Amendment may be separately executed in
any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to constitute one
and the same Amendment.

         SECTION 8. GOVERNING LAW. THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS
SHALL BE DEEMED CONTRACTS AND INSTRUMENTS MADE UNDER THE LAWS OF THE STATE OF
TEXAS AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND GOVERNED BY THE
LAWS OF THE STATE OF TEXAS AND THE LAWS OF THE UNITED STATES OF AMERICA, WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAW. CHAPTER 15 OF TEXAS REVISED CIVIL
STATUTES ANNOTATED ARTICLE 5069 (WHICH REGULATES CERTAIN REVOLVING CREDIT LOAN
ACCOUNTS AND REVOLVING TRI-PARTY ACCOUNTS) DOES NOT APPLY TO THIS AMENDMENT OR
TO THE NOTES.

         SECTION 9. Severability. If any term or provision of this Amendment or
of any Loan Document shall be determined to be illegal or unenforceable in any
jurisdiction, such term or provision shall, as to such jurisdiction, be illegal
or unenforceable, without affecting the remaining terms or provisions in that
jurisdiction or the legality or enforceability of such terms or provisions in
any other jurisdiction.

         SECTION 10.  WAIVER OF JURY TRIAL, PUNITIVE DAMAGES.  EACH OF THE
BORROWER, AGENTS AND LENDERS HEREBY (I) IRREVOCABLY WAIVES, TO THE MAXIMUM
EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY LITIGATION, DIRECTLY OR INDIRECTLY, AT ANY TIME ARISING OUT OF,
UNDER OR IN CONNECTION WITH THE LOAN DOCUMENTS OR ANY TRANSACTION CONTEMPLATED
THEREBY OR ASSOCIATED THEREWITH, BEFORE OR AFTER MATURITY; (II) IRREVOCABLY
WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO
CLAIM OR RECOVER IN ANY 



                                       6
<PAGE>   8


SUCH LITIGATION ANY EXEMPLARY, PUNITIVE OR CONSEQUENTIAL DAMAGES; (III)
CERTIFIES THAT NO PARTY HERETO NOR ANY REPRESENTATIVE OR AGENT OR COUNSEL FOR
ANY PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, OR IMPLIED THAT SUCH
PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING
WAIVERS; AND (IV) ACKNOWLEDGES THAT IT HAS BEEN INDUCED TO ENTER INTO THIS
AMENDMENT, THE OTHER LOAN DOCUMENTS AND THE TRANSACTIONS CONTEMPLATED HEREBY AND
THEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS CONTAINED
IN THIS SECTION.

         SECTION 11. FORUM SELECTION AND CONSENT TO JURISDICTION. ANY LITIGATION
BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AMENDMENT OR
ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS
(WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENTS, THE LENDERS OR THE
BORROWER SHALL BE BROUGHT AND MAINTAINED EXCLUSIVELY IN THE COURTS OF THE STATE
OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE NORTHERN DISTRICT OF
TEXAS; PROVIDED, HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT AGAINST ANY
COLLATERAL OR OTHER PROPERTY MAY BE BROUGHT, AT THE COLLATERAL AGENT'S OPTION,
IN THE COURTS OF ANY JURISDICTION WHERE SUCH COLLATERAL OR OTHER PROPERTY MAY BE
FOUND. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE JURISDICTION OF
THE COURTS OF THE STATE OF TEXAS AND THE UNITED STATES DISTRICT COURT FOR THE
NORTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION AS SET FORTH
ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED THEREBY IN
CONNECTION WITH SUCH LITIGATION. BORROWER FURTHER IRREVOCABLY CONSENTS TO THE
SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE PREPAID, OR BY PERSONAL SERVICE
WITHIN OR WITHOUT THE STATE OF TEXAS. FOR THE PURPOSE OF ANY ACTION OR
PROCEEDING INSTITUTED IN THE FEDERAL OR STATE COURTS OF TEXAS, EACH RESTRICTED
SUBSIDIARY OF THE BORROWER HEREBY IRREVOCABLY DESIGNATES BORROWER WITH OFFICES
ON THE DATE HEREOF AT 1400 WILLIAMS SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD,
IRVING, TEXAS 75039 TO RECEIVE FOR AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY,
SERVICE OF PROCESS IN TEXAS. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES,
TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR
HEREAFTER MAY HAVE TO THE LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY
SUCH COURT REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN
BROUGHT IN AN INCONVENIENT FORUM. TO THE EXTENT THAT THE BORROWER HAS OR
HEREAFTER MAY ACQUIRE ANY IMMUNITY FROM JURISDICTION OF ANY COURT OR FROM ANY
LEGAL PROCESS (WHETHER THROUGH SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT,
ATTACHMENT IN AID OF EXECUTION OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS
PROPERTY, BORROWER HEREBY IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS
OBLIGATIONS UNDER THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS.



                                       7
<PAGE>   9


         SECTION 12. Effectiveness. This Amendment shall become effective as of
June 29, 1998, when counterparts hereof executed on behalf of the Borrower and
each Lender (or notice thereof satisfactory to the Agent) shall have been
received by the Administrative Agent, and all conditions set forth in Section 4
hereof have been fulfilled.

         SECTION 13.  Entire Agreement.  THIS WRITTEN AMENDMENT AND THE OTHER
LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE 
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL 
AGREEMENTS OF THE PARTIES.

           THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                    [SIGNATURES BEGIN ON THE FOLLOWING PAGE]



                                       8
<PAGE>   10



         IN WITNESS WHEREOF, this Amendment is executed as of the date first
written above.

                                     BORROWER:

                                     PIONEER NATURAL RESOURCES COMPANY

                                     By: /s/ Garrett Smith
                                        ----------------------------------------
                                     Name:   M. Garrett Smith
                                     Title:  Executive Vice President and Chief
                                             Financial Officer

                                     LENDERS:

                                     NATIONSBANK, N.A., 
                                     successor-by-merger to NationsBank of
                                     Texas, N.A., individually and as 
                                     Administrative Agent and as Collateral 
                                     Agent

                                     By: /s/ Frank K. Stowers
                                         ---------------------------------------
                                     Name:   Frank K. Stowers
                                     Title:  Vice President

                                     CIBC INC.,
                                     individually and as Documentation Agent

                                     By: /s/ M.A.G. Corkum
                                        ----------------------------------------
                                     Name:   Michael A.G. Corkum
                                     Title:  Authorized Signatory

                                     MORGAN GUARANTY TRUST COMPANY OF NEW YORK, 
                                     individually and as Documentation Agent

                                     By: /s/ John Kowalczuk
                                        ----------------------------------------
                                     Name:   John Kowalczuk
                                     Title:  Vice President



                                       S-1

<PAGE>   11


                                     THE CHASE MANHATTAN BANK,
                                     individually and as Syndication Agent

                                     By: /s/ Lawrence Palumbo, Jr.
                                        ----------------------------------------
                                     Name:   Lawrence Palumbo, Jr.
                                     Title:  Vice President

                                     BANK OF AMERICA NATIONAL TRUST AND SAVINGS
                                     ASSOCIATION, individually and as Co-Agent

                                     By: /s/ Ronald E. McKaig
                                        ----------------------------------------
                                     Name:   Ronald E. McKaig
                                     Title:  Vice President

                                     THE BANK OF NEW YORK, 
                                     individually and as Co-Agent

                                     By: /s/ Raymond J. Palmer
                                        ----------------------------------------
                                     Name:   Raymond J. Palmer
                                     Title:  Vice President

                                     THE BANK OF NOVA SCOTIA,
                                     individually and as Co-Agent

                                     By: /s/ F.C.H. Ashby
                                        ----------------------------------------
                                     Name:   F.C.H. Ashby
                                     Title:  Senior Manager, Loan Operations

                                     ROYAL BANK OF CANADA, 
                                     individually and as Co-Agent

                                     By: /s/ Linda M. Stephens
                                        ----------------------------------------
                                     Name:   Linda M. Stephens
                                     Title:  Senior Manager

                                     UNION BANK OF CALIFORNIA, N.A., 
                                     individually and as Co-Agent

                                     By: /s/ Gary Shekerjian
                                        ----------------------------------------
                                     Name:   Gary Shekerjian
                                     Title:  Assistant Vice President



                                       S-2

<PAGE>   12



                                     WELLS FARGO BANK, N.A.,
                                     individually and as Co-Agent

                                     By: /s/ Lester J.N. Keliher
                                        ----------------------------------------
                                     Name:   Lester J.N. Keliher
                                     Title:  Vice President

                                     THE FUJI BANK, LIMITED-HOUSTON AGENCY, 
                                     individually and as Co-Agent

                                     By: /s/ David Kelley
                                        ----------------------------------------
                                     Name:   David Kelley
                                     Title:  Sr. Vice President

                                     DEN NORSKE BANK ASA, 
                                     individually and as Lead Manager

                                     By: /s/ J. Morten Kreutz
                                        ----------------------------------------
                                     Name:   J. Morten Kreutz
                                     Title:  Vice President

                                     By: /s/ Charles E. Hall
                                        ----------------------------------------
                                     Name:   Charles E. Hall
                                     Title:  Senior Vice President

                                     BANQUE PARIBAS,
                                     individually and as Lead Manager

                                     By: /s/ A. David Dodd
                                        ----------------------------------------
                                     Name:   A. David Dodd
                                     Title:  Vice President

                                     By: /s/ Marian Livingston
                                        ----------------------------------------
                                     Name:   Marian Livingston
                                     Title:  Vice President

                                     FIRST UNION NATIONAL BANK,
                                     individually and as Lead Manager

                                     By: /s/ Robert R. Wetteroff
                                        ----------------------------------------
                                     Name:   Robert R. Wetteroff
                                     Title:  Senior Vice President


                                       S-3

<PAGE>   13



                                     BANKERS TRUST COMPANY, 
                                     as a Lender

                                     By: /s/ Marcus Tarkington
                                        ----------------------------------------
                                     Name:   Marcus Tarkington
                                     Title:  Vice President

                                     CREDIT AGRICOLE INDOSUEZ, 
                                     as a Lender

                                     By:/s/ Dean Balice
                                        ----------------------------------------
                                     Name:  Dean Balice
                                     Title: Senior Vice President, Branch
                                            Manager

                                     By: /s/ W. Leroy Startz
                                        ----------------------------------------
                                     Name:   W. Leroy Startz
                                     Title:  First Vice President

                                     NATEXIS BANQUE,
                                     as a Lender BFCE

                                     By: /s/ Mark A. Harrington
                                        ----------------------------------------
                                     Name:   Mark A. Harrington
                                     Title:  Vice President and Regional
                                             Manager

                                     By: /s/ N. Eric Ditges
                                        ----------------------------------------
                                     Name:   N. Eric Ditges
                                     Title:  Assistant Vice President

                                     TORONTO DOMINION (TEXAS), INC., 
                                     as a Lender

                                     By: /s/ Debbie A. Greene
                                        ----------------------------------------
                                     Name:   Debbie A. Greene
                                     Title:  Vice President

                                     THE TOYO TRUST & BANKING CO., LTD.,
                                     as a Lender

                                     By: /s/ T. Mikumo
                                        ----------------------------------------
                                     Name:   T. Mikumo
                                     Title:  Vice President


                                       S-4

<PAGE>   14



                                     WACHOVIA BANK, N.A.,
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     THE DAI-ICHI KANGYO BANK, LTD., NEW YORK
                                     BRANCH, as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     THE SANWA BANK, LIMITED, 
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     KBC BANK N.V.,
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:


                                       S-5

<PAGE>   15



                                    Exhibit J

                    Form of Designated Officer's Certificate

         Reference is made to (i) the Primary Credit Facility pursuant to that
certain Amended and Restated Credit Facility Agreement dated as of December 18,
1997, as amended, by and among Borrower, NationsBank, N.A., as Administrative
Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New
York, as Documentation Agent, The Chase Manhattan Bank, as Syndication Agent,
the Co-Agents party thereto, and the Lenders from time to time parties thereto
(the "Primary Credit Agreement") and (ii) the 364 Day Credit Facility pursuant
to that certain Amended and Restated Credit Facility Agreement dated as of
December 18, 1997, as amended, by and among Borrower, NationsBank, N.A., as
Administrative Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust
Company of New York, as Documentation Agent, The Chase Manhattan Bank, as
Syndication Agent, the Co-Agents party thereto, and the Lenders from time to
time parties thereto (the "364 Day Credit Agreement" and, together with the
Primary Credit Facility, the "Credit Agreements"). Terms which are defined in
the Credit Agreements and which are used but not defined herein are used herein
with the meanings given them in the Credit Agreements.

         This Certificate is furnished pursuant to Section 5.1(b)(2) of the
Credit Agreements. Together herewith the Borrower is furnishing to Managing
Agents, the Co-Agents and each Lender the Borrower's [Financial Statements] (the
"Financial Statements") as of _____________ (the "Reporting Date"). The Borrower
hereby represents, warrants, and acknowledges to Agents and each Lender that:

         (a)      the Designated Officer of the Borrower signing this instrument
                  is a duly elected, qualified and acting officer of the
                  Borrower;

         (b)      the Financial Statements are accurate and complete and satisfy
                  the requirements of the Credit Agreements;

         (c)      attached as Schedule I hereto is a schedule of calculations
                  showing compliance (or noncompliance, as the case may be) as
                  of the Reporting Date with the requirements of Section 5.3 of
                  the Credit Agreements; and

         (d)      on the Reporting Date, the Borrower was, and on the date
                  hereof the Borrower is, in full compliance with the disclosure
                  requirements of Section 5.1(d) of the Credit Agreements, and
                  no Default otherwise existed on the Reporting Date or
                  otherwise exists on the date of this Certificate [except for
                  Default(s) under Section(s) _______________  of the Credit
                  Agreements, which [is/are] more fully described on a schedule
                  attached hereto].



                               Exhibit J - Page 1

<PAGE>   16



         The Designated Officer of the Borrower signing this instrument hereby
certifies that he has reviewed the Loan Documents and the Financial Statements
and has otherwise undertaken such inquiry as is in his opinion necessary to
enable him to express an informed opinion with respect to the above
representations, warranties and acknowledgments of the Borrower and, to the best
of his knowledge, such representations, warranties, and acknowledgments are
true, correct and complete.

                                     PIONEER NATURAL RESOURCES COMPANY

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:
                                     
                                     Date:
                                          --------------------------------------


                               Exhibit J - Page 2

<PAGE>   17


                                   Schedule I

================================================================================
COMPLIANCE WITH FINANCIAL COVENANTS AS OF _____________ . ($ in 000's)
================================================================================

A.     EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO
                                                                      ========

            Minimum ratio allowed          :1      
                                        ========

B.     CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
       CAPITALIZATION
                                                                      ========

            Maximum ratio allowed           %     
                                        ========

================================================================================
COMPUTATION OF FINANCIAL REQUIREMENTS AND RATIOS AS OF ______________
================================================================================

A.     EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO
       (Section 5.3(a)) ($ in 000's)

<TABLE>
          <S>                                                                       <C>    
          (i)  EBITDAX (as defined in Section 5.3(a))

               For the period ended __________ , the sum of the amounts for such
               period of Consolidated net income, Consolidated Interest Expense,
               depreciation expense, depletion expense, amortization expense,
               federal and state income taxes, exploration and abandonment
               expense and other non-cash charges and expenses, all as
               determined on a Consolidated basis for Borrower and its
               Consolidated Subsidiaries;                                            $
                                                                                      ---------

          (ii) CONSOLIDATED INTEREST EXPENSE (as defined in Section 5.3(a))

               For the period ended ___________, total interest expense, whether 
               paid or accrued, of Borrower and its Consolidated Subsidiaries on 
               a Consolidated basis, including, without limitation, all
               commissions, discounts and other fees and charges owed with
               respect to Letters of Credit.                                         $ 
                                                                                      ---------

               CONSOLIDATED INTEREST EXPENSE                                         $              
                                                                                      =========

               EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO ((i)(ii))              $              
                                                                                      =========
 
               Minimum ratio allowed         :1     
                                          ==========
</TABLE>


                               Exhibit J - Page 3


<PAGE>   18


B.       CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
         CAPITALIZATION (Section 5.3(b)) ($ in 000's)

<TABLE>
            <S>                                                                     <C> 
            (i) CONSOLIDATED TOTAL FUNDED DEBT (as defined in Section 1.1)

                (a) All indebtedness of Borrower and its Consolidated
                    Subsidiaries for borrowed money                                  $
                                                                                      ---------

                (b) Plus indebtedness of Borrower and its Consolidated
                    Subsidiaries constituting an obligation to pay the deferred
                    purchase price of property or services (other than customary
                    payment terms taken in the ordinary course of the business)      $
                                                                                      ---------

                (c) Plus indebtedness of Borrower and its Consolidated
                    Subsidiaries evidenced by a bond, debenture, note or similar
                    instrument                                                       $
                                                                                      ---------

                (d) Plus principal obligations under leases capitalized in
                    accordance with GAAP under which either Borrower or any of
                    its Consolidated Subsidiaries is the lessee                      $
                                                                                      ---------

                (e) Plus indebtedness or obligations of the type described in
                    clauses (a), (b), (c) or (d) of the definition of Debt,
                    which are secured by a Lien on any property owned by
                    Borrower or any of its Consolidated Subsidiaries, whether or
                    not such indebtedness or obligations have been assumed by
                    Borrower or any of its Consolidated Subsidiaries (limited
                    however to the lesser of (1) the amount of its liability or
                    (2) the value of such property) (excluding Debt of the type
                    referred to in clause (e) of the definition of "Debt")           $
                                                                                      ---------

                (f) Plus the undischarged balance of any production payment
                    created by Borrower or any of its Consolidated Subsidiaries
                    or for the creation of which Borrower or its Consolidated
                    Subsidiaries directly or indirectly received payment.            $
                                                                                      ---------

                CONSOLIDATED TOTAL FUNDED DEBT                                       $             
                                                                                      =========
</TABLE>


                               Exhibit J - Page 4


<PAGE>   19
 

<TABLE>
<S>        <C>                                                                      <C>
           (ii) TOTAL CAPITALIZATION (as defined in Section 1.1)

                (a) Consolidated Total Funded Debt of the Borrower and its
                    Consolidated Subsidiaries (See B(i) above)                       $
                                                                                      ---------

                (b) Plus Consolidated shareholders' equity of the Borrower and
                    its Consolidated Subsidiaries                                    $
                                                                                      ---------

                TOTAL CAPITALIZATION                                                 $             
                                                                                      =========

CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
CAPITALIZATION((i)/(ii))                                                                       %
                                                                                      =========

                Maximum ratio allowed                                                          %     
                                                                                      =========
</TABLE>



                               Exhibit J - Page 5


<PAGE>   1

                                                                   EXHIBIT 10.32

                            [364 DAY CREDIT FACILITY]

================================================================================

                               FIRST AMENDMENT TO
                 AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

                                  by and among

                       PIONEER NATURAL RESOURCES COMPANY,
                                  as Borrower,

                                       and

                               NATIONSBANK, N.A.,
                            as Administrative Agent,

                                       and

                                   CIBC INC.,
                             as Documentation Agent,

                                       and

                   MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                             as Documentation Agent,

                                       and

                            THE CHASE MANHATTAN BANK,
                              as Syndication Agent,

                         THE CO-AGENTS SIGNATORY HERETO,

                                       and

                       THE OTHER LENDERS SIGNATORY HERETO


                            Dated as of June 29, 1998

================================================================================
<PAGE>   2



                               FIRST AMENDMENT TO
                 AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

         THIS FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT FACILITY AGREEMENT
(herein called this "Amendment"), is made as of June 29, 1998, by and among
PIONEER NATURAL RESOURCES COMPANY, a Delaware corporation (the "Borrower"),
NATIONSBANK, N.A., as successor-by-merger to NationsBank of Texas, N.A., as
Administrative Agent and Collateral Agent, CIBC INC., as Documentation Agent,
MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation Agent, THE CHASE
MANHATTAN BANK, as Syndication Agent, the "Co-Agents" party to the Credit
Agreement (as herein defined), and the other Lenders from time to time parties
to the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents have heretofore entered into a certain Amended and
Restated Credit Facility Agreement - 364 Day Credit Facility, dated as of
December 18, 1997 (herein the "Credit Agreement"); and

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents now intend to amend the Credit Agreement in certain
respects; and

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, each of the Borrower, the Lenders, the Managing
Agents, the Collateral Agent and the Co-Agents hereby agree as follows:

         SECTION 1. Defined Terms. All capitalized terms used but not otherwise
defined herein shall have the meanings given in the Credit Agreement.

         SECTION 2.  Amendments to Credit Agreement

         a.            The Credit Agreement is hereby amended by modifying each
                  reference therein to "NationsBank of Texas, N.A." to read
                  "NationsBank, N.A., successor-by-merger to NationsBank of
                  Texas, N.A."

         b.            The definitions of "Amendment Fee Rate", "Eurodollar 
                  Margin" and "Facility Amount" in Section 1.1 of the Credit 
                  Agreement are hereby amended and restated to read in their 
                  entirety as follows:

         "        "Amendment Fee Rate" means 15.0 basis points."

         "        "Eurodollar Margin" means, on any date, with respect to each
         Eurodollar Portion of a Revolving Loan, the sum of (i) the applicable
         Commitment Utilization Margin plus (ii) the number of basis points per
         annum set forth below based on the Applicable Rating Level on such
         date:


<PAGE>   3


<TABLE>
<CAPTION>
===========================================================
        Applicable
       Rating Level
- -----------------------------------------------------------
<S>                                     <C>      
         Level I                        20.0 b.p.
- -----------------------------------------------------------
         Level II                       22.0 b.p.
- -----------------------------------------------------------
         Level III                      25.0 b.p.
- -----------------------------------------------------------
         Level IV                       38.0 b.p.
- -----------------------------------------------------------
         Level V                        47.0 b.p.
===========================================================
</TABLE>


         Changes in the Eurodollar Margin will occur automatically without prior
         notice. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Eurodollar Margin."

         "     "Facility Amount" means the aggregate amount of the Commitments
         (which amount shall initially be $100,000,000), as such amount may be
         reduced from time to time pursuant to the terms of this Agreement."

         c.         Section 1.1 of the Credit Agreement is hereby amended by
               inserting the following definitions of "Commitment Utilization",
               "Commitment Utilization Level", "Commitment Utilization Margin",
               "Year 2000 Compliant" and "Year 2000 Problem" in appropriate
               alphabetical order:

         "     "Commitment Utilization" means, for any period, the ratio of (i) 
         the aggregate amount of then outstanding Loans plus then existing LC
         Obligations to (ii) the current Facility Amount."

         "     "Commitment Utilization Level" means the level set forth below 
         that corresponds to the lowest of the ratings issued from time to time 
         by Moody's and S&P, as applicable, for Borrower's senior unsecured
         long-term debt:

<TABLE>
<CAPTION>
================================================================================
                         Moody's                 S&P
- --------------------------------------------------------------------------------
<S>                   <C>                   <C>           
Level A               Baa3 or better        BBB- or better
- --------------------------------------------------------------------------------
Level B               Less than Baa3        Less than BBB-
================================================================================
</TABLE>

         For example, if the Moody's rating is Ba1 and the S&P rating is BBB,
         Level B shall apply. For purposes of the foregoing, (i) if ratings for
         Borrower's senior unsecured long-term debt shall not be available from
         S&P or Moody's, Level B shall be deemed applicable; and (ii) if any of
         the Rating Agencies shall change its ratings nomenclature prior to the
         date all Obligations have been paid and the Commitments canceled,
         Borrower and the Lenders shall negotiate in good faith to amend the
         references to


                                        2


<PAGE>   4



         specific ratings in this definition to reflect such change, and pending
         such amendment, if an appropriate Commitment Utilization Level is
         otherwise not determinable based upon the foregoing grid, the last
         Commitment Utilization Level in effect at the time of such change shall
         continue to apply."

         "     "Commitment Utilization Margin" means, on any date, the number of
         basis points per annum set forth below based on the Commitment
         Utilization Level on such date:


<TABLE>
<CAPTION>
================================================================================
                              Commitment Utilization Margin
- --------------------------------------------------------------------------------
                                 Commitment                      Commitment
      Commitment                Utilization is                  Utilization is
   Utilization Level          "< or equal to .50"                  ">.50"
- --------------------------------------------------------------------------------
<S>                           <C>                              <C>     
       Level A                     0 b.p.                         5.0 b.p.
- --------------------------------------------------------------------------------
       Level B                     0 b.p.                        10.0 b.p.
================================================================================
</TABLE>

         ; provided, however, for the purpose of determining the Commitment
         Utilization Margin for all periods ending prior to or on June 30, 1999,
         the Commitment Utilization of Borrower shall be deemed to be greater
         than ".50". Changes in the Commitment Utilization Margin will occur
         automatically without prior notice."

         "     "Year 2000 Compliant" has the meaning given it in Section 
               4.1(s)."

         "     "Year 2000 Problem" has the meaning given it in Section 4.1(s)."

         d.         Section 4.1 of the Credit Agreement is hereby amended by
               inserting the following Section 4.1(s) after Section 4.1(r):

         "(s)  Year 2000 Compliance. Borrower has (i) initiated a review
               and assessment of all areas within its and each of its
               Subsidiaries' business and operations (including those affected
               by suppliers and vendors) that could be adversely affected by the
               Year 2000 Problem (as herein defined), (ii) developed a plan and
               time line for addressing the Year 2000 Problem on a timely basis,
               and (iii) to date, implemented that plan in accordance with that
               timetable. Borrower reasonably believes that all computer
               applications (including those of its suppliers and vendors) that
               are material to its or any of its Subsidiaries' business and
               operations will be Year 2000 Compliant, except to the extent that
               a failure to do so could not reasonably be expected to have
               Material Adverse Effect. As used herein, the term "Year 2000
               Problem" means the risk that computer applications used by the
               Borrower or any of its Subsidiaries (or its suppliers and
               vendors) may be unable to recognize and perform properly date-
               sensitive functions involving certain dates prior to and any date
               after December 31, 1999. As used herein, the term "Year 2000
               Compliant" means that all computer applications





                                       3
<PAGE>   5
               will on a timely basis be able to perform properly date-
               sensitive functions for all dates before and after January 1,
               2000."

         e.        Section 5.1 of the Credit Agreement is hereby amended by
               inserting the following Section 5.1(m) after Section 5.1(l):

         "(m)  Year 2000 Compliance. Borrower will promptly notify
               Administrative Agent in the event Borrower discovers or
               determines that any computer application (including those of its
               suppliers and vendors) that is material to its or any of its
               Subsidiaries' business and operations will not be Year 2000
               Compliant on a timely basis, except to the extent that such
               failure could not reasonably be expected to have a Material
               Adverse Effect."

         f.        Section 5.3(a) of the Credit Agreement is hereby amended and
               restated to read in its entirety as follows:

               "(a) EBITDAX to Consolidated Interest Expense Ratio. The ratio 
         of Borrower's "EBITDAX" to "Consolidated Interest Expense" for  the
         last four rolling Fiscal Quarters (i) ending June 30, 1998 and 
         September 30, 1998, will not be less than 2.50 to 1.0, (ii) ending 
         December 31, 1998, will not be less than 2.75 to 1.0, (iii) ending 
         March 31, 1999, will not be less than 3.00 to 1.0, (iv) ending June
         30,    1999, will not be less than 3.25 to 1.0, and (v) ending after
         June 30,  1999, will not be less than 3.75 to 1.0; provided, however,
         that for  the periods for calculation ending on or before December 31,
         1998, each reference to "for the last four rolling Fiscal Quarters"
         shall be  deemed to be a reference to the period from April 1, 1998
         through the  date of such calculation. As used in this paragraph, the
         term  "Consolidated Interest Expense" means for any period, total
         interest  expense, whether paid or accrued, of Borrower and its
         Subsidiaries on a Consolidated basis, including, without limitation,
         all commissions,  discounts and other fees and charges owed with
         respect to Letters of  Credit (as defined in the Primary Credit
         Facility). As used in this  paragraph, the term "EBITDAX" means for
         any period the sum of the  amounts for such period of Consolidated net
         income, Consolidated  Interest Expense, depreciation expense,
         depletion expense, amortization expense, federal and state income
         taxes, exploration and abandonment  expense and other non-cash charges
         and expenses, all as determined on a Consolidated basis for Borrower
         and its Subsidiaries."

         g.        Section 5.3(b) of the Credit Agreement is hereby amended 
               and restated to read in its entirety as follows:

               "(b) Consolidated Total Funded Debt to Total Capitalization.
         Borrower's Consolidated Total Funded Debt to Total Capitalization will
         not (i) as of the last day of the Fiscal Quarters ending June 30, 1998
         and September 30, 1998, be greater than 62.5%, and (ii) as of the last
         day of any Fiscal Quarter ending after September 30, 1998, be greater
         than 60%."


                                        4

<PAGE>   6



         h.        The fourth sentence of Section 8.17 of the Credit Agreement
               is hereby amended and restated to read in its entirety as
               follows:

         "FOR THE PURPOSE OF ANY ACTION OR PROCEEDING INSTITUTED IN THE FEDERAL
         OR STATE COURTS OF TEXAS, EACH RESTRICTED SUBSIDIARY OF THE BORROWER
         HEREBY IRREVOCABLY DESIGNATES BORROWER WITH OFFICES ON THE DATE HEREOF
         AT 1400 WILLIAMS SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD, IRVING,
         TEXAS 75039 TO RECEIVE FOR AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY,
         SERVICES OF PROCESS IN TEXAS."

         i.        The Credit Agreement is hereby amended by replacing Exhibit J
               to the Credit Agreement with Exhibit J to this Amendment.

         j.        The Credit Agreement is hereby amended by replacing
               Schedule 1 to the Credit Agreement with Schedule 1 to this
               Amendment.

         k.        Schedule 3 attached to the Credit Agreement is hereby
               amended by deleting therefrom the reference to "Pioneer Natural
               Resources (GPC) Inc., a Delaware corporation".

         SECTION 3. Representations and Warranties. To confirm each Lender's
understanding concerning Borrower and its businesses, properties and
obligations, and to induce the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender to enter into this Amendment, the Borrower hereby
reaffirms to the Managing Agents, the Collateral Agent, the Co-Agents and each
Lender that, as of the date hereof, its representations and warranties contained
in Section 4.1 of the Credit Agreement (as amended by this Amendment) and in the
other Loan Documents to which it is a party (except to the extent such
representations and warranties relate solely to an earlier date) are true and
correct and additionally represents and warrants as follows:

A.       The execution and delivery of this Amendment and the performance by
         the Borrower and the Restricted Subsidiaries of their respective
         obligations under this Amendment, the Credit Agreement and the other
         Loan Documents, as amended hereby, are within the Borrower's or such
         Restricted Subsidiaries' corporate or partnership powers, have been
         duly authorized by all necessary corporate or partnership action, have
         received all necessary governmental approval (if any shall be
         required), and do not and will not contravene or conflict with any
         provision of law or of the Borrower's or such Restricted Subsidiaries'
         charter or bylaws or partnership agreement or of any contractual
         restriction, law or governmental regulation or court decree or order
         binding on or affecting the Borrower or such Restricted Subsidiary.

B.       This Amendment and the Credit Agreement as amended hereby are, and
         the other Loan Documents when duly executed and delivered will be,
         legal, valid and binding obligations of the Borrower and each
         Restricted Subsidiary which is a party hereto or thereto, enforceable
         in accordance with their terms except as such enforcement may be
         limited by bankruptcy, insolvency or similar laws of general
         application relating to the enforcement of creditors' rights generally
         and by general principles of equity.



                                       5
<PAGE>   7



         SECTION 4. Conditions to Effectiveness. The effectiveness of this
Amendment is conditioned upon receipt by the Administrative Agent of all the
following documents and items, each in form and substance reasonably
satisfactory to the Administrative Agent:

A.       this Amendment executed by the Borrower and the Required Lenders.

B.       Borrower will pay, or cause the payment, to Administrative Agent for
         the account of each Lender a non-refundable amendment fee payable to
         each Lender determined by applying the Amendment Fee Rate to such
         Lender's Percentage Share of the Facility Amount as of the date of this
         Amendment.

C.       Such other documents or items that the Administrative Agent may
         reasonably request.

         SECTION 5. Reaffirmation of Credit Agreement. This Amendment
constitutes a "Loan Document" as defined in the Credit Agreement and shall be
deemed to be an amendment to the Credit Agreement, and the Credit Agreement, as
amended hereby, is hereby ratified, approved and confirmed in each and every
respect. All references to the Credit Agreement or the Credit Facility Agreement
in any other document, instrument, agreement or writing shall hereafter be
deemed to refer to the Credit Agreement as amended hereby.

         SECTION 6. Parties in Interest. All grants, covenants and agreements
contained in this Amendment shall bind and inure to the benefit of the parties
thereto and their respective successors and assigns; provided, however, that no
Restricted Subsidiary may assign or transfer any of its rights or delegate any
of its duties or obligations under this Amendment or any Loan Document without
the prior written consent of all Lenders.

         SECTION 7. Counterparts. This Amendment may be separately executed in
any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to constitute one
and the same Amendment.

         SECTION 8. GOVERNING LAW. THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS
SHALL BE DEEMED CONTRACTS AND INSTRUMENTS MADE UNDER THE LAWS OF THE STATE OF
TEXAS AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND GOVERNED BY THE
LAWS OF THE STATE OF TEXAS AND THE LAWS OF THE UNITED STATES OF AMERICA, WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAW. CHAPTER 15 OF TEXAS REVISED CIVIL
STATUTES ANNOTATED ARTICLE 5069 (WHICH REGULATES CERTAIN REVOLVING CREDIT LOAN
ACCOUNTS AND REVOLVING TRI-PARTY ACCOUNTS) DOES NOT APPLY TO THIS AMENDMENT OR
TO THE NOTES.

         SECTION 9. Severability. If any term or provision of this Amendment or
of any Loan Document shall be determined to be illegal or unenforceable in any
jurisdiction, such term or provision shall, as to such jurisdiction, be illegal
or unenforceable, without affecting the remaining terms or provisions in that
jurisdiction or the legality or enforceability of such terms or provisions in
any other jurisdiction.


                                       6
<PAGE>   8


         SECTION 10. WAIVER OF JURY TRIAL, PUNITIVE DAMAGES. EACH OF THE
BORROWER, AGENTS AND LENDERS HEREBY (I) IRREVOCABLY WAIVES, TO THE MAXIMUM
EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY LITIGATION, DIRECTLY OR INDIRECTLY, AT ANY TIME ARISING OUT OF,
UNDER OR IN CONNECTION WITH THE LOAN DOCUMENTS OR ANY TRANSACTION CONTEMPLATED
THEREBY OR ASSOCIATED THEREWITH, BEFORE OR AFTER MATURITY; (II) IRREVOCABLY
WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO
CLAIM OR RECOVER IN ANY SUCH LITIGATION ANY EXEMPLARY, PUNITIVE OR CONSEQUENTIAL
DAMAGES; (III) CERTIFIES THAT NO PARTY HERETO NOR ANY REPRESENTATIVE OR AGENT OR
COUNSEL FOR ANY PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, OR IMPLIED
THAT SUCH PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE
FOREGOING WAIVERS; AND (IV) ACKNOWLEDGES THAT IT HAS BEEN INDUCED TO ENTER INTO
THIS AMENDMENT, THE OTHER LOAN DOCUMENTS AND THE TRANSACTIONS CONTEMPLATED
HEREBY AND THEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS
CONTAINED IN THIS SECTION.

         SECTION 11. FORUM SELECTION AND CONSENT TO JURISDICTION. ANY LITIGATION
BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AMENDMENT OR
ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS
(WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENTS, THE LENDERS OR THE
BORROWER SHALL BE BROUGHT AND MAINTAINED EXCLUSIVELY IN THE COURTS OF THE STATE
OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE NORTHERN DISTRICT OF
TEXAS; PROVIDED, HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT AGAINST ANY
COLLATERAL OR OTHER PROPERTY MAY BE BROUGHT, AT THE COLLATERAL AGENT'S OPTION,
IN THE COURTS OF ANY JURISDICTION WHERE SUCH COLLATERAL OR OTHER PROPERTY MAY BE
FOUND. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE JURISDICTION OF
THE COURTS OF THE STATE OF TEXAS AND THE UNITED STATES DISTRICT COURT FOR THE
NORTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION AS SET FORTH
ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED THEREBY IN
CONNECTION WITH SUCH LITIGATION. BORROWER FURTHER IRREVOCABLY CONSENTS TO THE
SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE PREPAID, OR BY PERSONAL SERVICE
WITHIN OR WITHOUT THE STATE OF TEXAS. FOR THE PURPOSE OF ANY ACTION OR
PROCEEDING INSTITUTED IN THE FEDERAL OR STATE COURTS OF TEXAS, EACH RESTRICTED
SUBSIDIARY OF THE BORROWER HEREBY IRREVOCABLY DESIGNATES BORROWER WITH OFFICES
ON THE DATE HEREOF AT 1400 WILLIAMS SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD,
IRVING, TEXAS 75039 TO RECEIVE FOR AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY,
SERVICE OF PROCESS IN TEXAS. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES,
TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR
HEREAFTER MAY HAVE TO THE LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY
SUCH COURT REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN



                                       7
<PAGE>   9


BROUGHT IN AN INCONVENIENT FORUM. TO THE EXTENT THAT THE BORROWER HAS OR
HEREAFTER MAY ACQUIRE ANY IMMUNITY FROM JURISDICTION OF ANY COURT OR FROM ANY
LEGAL PROCESS (WHETHER THROUGH SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT,
ATTACHMENT IN AID OF EXECUTION OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS
PROPERTY, BORROWER HEREBY IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS
OBLIGATIONS UNDER THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS.

         SECTION 12. Effectiveness. This Amendment shall become effective as of
June 29, 1998, when counterparts hereof executed on behalf of the Borrower and
each Lender (or notice thereof satisfactory to the Agent) shall have been
received by the Administrative Agent, and all conditions set forth in Section 4
hereof have been fulfilled.

         SECTION 13.  Entire Agreement.  THIS WRITTEN AMENDMENT AND THE OTHER
LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS,
OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                    [SIGNATURES BEGIN ON THE FOLLOWING PAGE]



                                        8

<PAGE>   10



         IN WITNESS WHEREOF, this Amendment is executed as of the date first
written above.

                                     BORROWER:

                                     PIONEER NATURAL RESOURCES COMPANY

                                     By: /s/ Garrett Smith
                                        ----------------------------------------
                                     Name:   M. Garrett Smith
                                     Title:  Executive Vice President and Chief
                                             Financial Officer

                                     LENDERS:

                                     NATIONSBANK, N.A.,
                                     successor-by-merger to NationsBank of 
                                     Texas, N.A., individually and as 
                                     Administrative Agent and as Collateral
                                     Agent

                                     By: /s/ Frank K. Stowers
                                        ----------------------------------------
                                     Name:   Frank K. Stowers
                                     Title:  Vice President

                                     CIBC INC.,
                                     individually and as Documentation Agent

                                     By: /s/ M. A.G. Corkum
                                        ----------------------------------------
                                     Name:   Michael A.G. Corkum
                                     Title:  Authorized Signatory

                                     MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                                     individually and as Documentation Agent

                                     By: /s/ John Kowalczuk
                                        ----------------------------------------
                                     Name:   Michael Kowalczuk
                                     Title:  Vice President



                                       S-1

<PAGE>   11


                                     THE CHASE MANHATTAN BANK,
                                     individually and as Syndication Agent

                                     By: /s/ Lawrence Palumbo, Jr.
                                        ----------------------------------------
                                     Name:   Lawrence Palumbo, Jr.
                                     Title:  Vice President

                                     BANK OF AMERICA NATIONAL TRUST AND SAVINGS
                                     ASSOCIATION, individually and as Co-Agent

                                     By: /s/ Ronald E. McKaig
                                        ----------------------------------------
                                     Name:    Ronald E. McKaig
                                     Title:   Vice President

                                     THE BANK OF NEW YORK,
                                     individually and as Co-Agent

                                     By: /s/ Raymond J. Palmer
                                        ----------------------------------------
                                     Name:   Raymond J. Palmer
                                     Title:  Vice President

                                     THE BANK OF NOVA SCOTIA, 
                                     individually and as Co-Agent

                                     By: /s/ F.C.H. Ashby
                                        ----------------------------------------
                                     Name:   F.C.H. Ashby
                                     Title:  Senior Manager, Loan Operations

                                     ROYAL BANK OF CANADA,
                                     individually and as Co-Agent

                                     By: /s/ Linda M. Stephens
                                        ----------------------------------------
                                     Name:   Linda M. Stephens
                                     Title:  Senior Manager

                                     UNION BANK OF CALIFORNIA, N.A.,
                                     individually and as Co-Agent

                                     By: /s/ Gary Shekerjian
                                        ----------------------------------------
                                     Name:   Gary Shekerjian
                                     Title:  Assistant Vice President


                                       S-2

<PAGE>   12



                                     WELLS FARGO BANK, N.A.,
                                     individually and as Co-Agent

                                     By: /s/ Lester J.N. Keliher
                                        ----------------------------------------
                                     Name:   Lester J.N. Keliher
                                     Title:  Vice President

                                     THE FUJI BANK, LIMITED-HOUSTON AGENCY,
                                     individually and as Co-Agent

                                     By: /s/ David Kelley
                                        ----------------------------------------
                                     Name:   David Kelley
                                     Title:  Sr. Vice President

                                     DEN NORSKE BANK ASA,
                                     individually and as Lead Manager

                                     By: /s/ J. Morten Kreutz
                                        ----------------------------------------
                                     Name:   J. Morten Kreutz
                                     Title:  Vice President

                                     By: /s/ Charles E. Hall
                                        ----------------------------------------
                                     Name:   Charles E. Hall
                                     Title:  Senior Vice President

                                     BANQUE PARIBAS, 
                                     individually and as Lead Manager

                                     By: /s/ A. David Dodd
                                        ----------------------------------------
                                     Name:   A. David Dodd
                                     Title:  Vice President

                                     By: /s/ Marian Livingston
                                        ----------------------------------------
                                     Name:   Marian Livingston
                                     Title:  Vice President

                                     FIRST UNION NATIONAL BANK,
                                     individually and as Lead Manager

                                     By: /s/ Robert R. Wetteroff
                                        ----------------------------------------
                                     Name:   Robert R. Wetteroff
                                     Title:  Senior Vice President


                                       S-3

<PAGE>   13


                                     BANKERS TRUST COMPANY,
                                     as a Lender

                                     By: /s/ Marcus Tarkington
                                        ----------------------------------------
                                     Name:   Marcus Tarkington
                                     Title:  Vice President

                                     CREDIT AGRICOLE INDOSUEZ,
                                     as a Lender

                                     By: /s/ W. Leroy Startz
                                        ----------------------------------------
                                     Name:   W. Leroy Startz
                                     Title:  First Vice President

                                     By: /s/ Dean Balice
                                        ----------------------------------------
                                     Name:   Dean Balice
                                     Title:  Senior Vice President, Branch
                                             Manager

                                     NATEXIS BANQUE,
                                     as a Lender BFCE

                                     By: /s/ Mark A. Harrington
                                        ----------------------------------------
                                     Name:   Mark A. Harrington
                                     Title:  Vice President and Regional
                                             Manager

                                     By: /s/ N. Eric Ditges
                                        ----------------------------------------
                                     Name:   N. Eric Ditges
                                     Title:  Assistant Vice President

                                     TORONTO DOMINION (TEXAS), INC.,
                                     as a Lender

                                     By: /s/ Debbie A. Greene
                                        ----------------------------------------
                                     Name:   Debbie A. Greene
                                     Title:  Vice President

                                     THE TOYO TRUST & BANKING CO., LTD.,
                                     as a Lender

                                     By: /s/ T. Mikumo
                                        ----------------------------------------
                                     Name:   T. Mikumo
                                     Title:  Vice President


                                       S-4

<PAGE>   14

                                     WACHOVIA BANK, N.A.,
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     THE DAI-ICHI KANGYO BANK, LTD., NEW YORK
                                     BRANCH, as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     THE SANWA BANK, LIMITED,
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     KBC BANK N.V.,
                                     as a Lender

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                       S-5

<PAGE>   15



                                    Exhibit J

                    Form of Designated Officer's Certificate

         Reference is made to (i) the Primary Credit Facility pursuant to that
certain Amended and Restated Credit Facility Agreement dated as of December 18,
1997, as amended, by and among Borrower, NationsBank, N.A., as Administrative
Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New
York, as Documentation Agent, The Chase Manhattan Bank, as Syndication Agent,
the Co-Agents party thereto, and the Lenders from time to time parties thereto
(the "Primary Credit Agreement") and (ii) the 364 Day Credit Facility pursuant
to that certain Amended and Restated Credit Facility Agreement dated as of
December 18, 1997, as amended, by and among Borrower, NationsBank, N.A., as
Administrative Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust
Company of New York, as Documentation Agent, The Chase Manhattan Bank, as
Syndication Agent, the Co-Agents party thereto, and the Lenders from time to
time parties thereto (the "364 Day Credit Agreement" and, together with the
Primary Credit Facility, the "Credit Agreements"). Terms which are defined in
the Credit Agreements and which are used but not defined herein are used herein
with the meanings given them in the Credit Agreements.

         This Certificate is furnished pursuant to Section 5.1(b)(2) of the
Credit Agreements. Together herewith the Borrower is furnishing to Managing
Agents, the Co-Agents and each Lender the Borrower's [Financial Statements] (the
"Financial Statements") as of _____________ (the "Reporting Date"). The Borrower
hereby represents, warrants, and acknowledges to Agents and each Lender that:

         (a) the Designated Officer of the Borrower signing this instrument is a
             duly elected, qualified and acting officer of the Borrower;

         (b) the Financial Statements are accurate and complete and satisfy the
             requirements of the Credit Agreements;

         (c) attached as Schedule I hereto is a schedule of calculations showing
             compliance (or noncompliance, as the case may be) as of the
             Reporting Date with the requirements of Section 5.3 of the Credit
             Agreements; and

         (d) on the Reporting Date, the Borrower was, and on the date hereof the
             Borrower is, in full compliance with the disclosure requirements of
             Section 5.1(d) of the Credit Agreements, and no Default otherwise
             existed on the Reporting Date or otherwise exists on the date of
             this Certificate [except for Default(s) under Section(s)_________
             of the Credit Agreements, which [is/are] more fully described on a
             schedule attached hereto].

                               Exhibit J - Page 1

<PAGE>   16



         The Designated Officer of the Borrower signing this instrument hereby
certifies that he has reviewed the Loan Documents and the Financial Statements
and has otherwise undertaken such inquiry as is in his opinion necessary to
enable him to express an informed opinion with respect to the above
representations, warranties and acknowledgments of the Borrower and, to the best
of his knowledge, such representations, warranties, and acknowledgments are
true, correct and complete.

                                     PIONEER NATURAL RESOURCES COMPANY

                                     By:
                                        ----------------------------------------
                                     Name:
                                     Title:

                                     Date:
                                          --------------------------------------


                               Exhibit J - Page 2

<PAGE>   17



                                   Schedule I

================================================================================
COMPLIANCE WITH FINANCIAL COVENANTS AS OF _____________ . ($ in 000's)
================================================================================

A.     EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO
                                                                      ========

            Minimum ratio allowed          :1      
                                        ========

B.     CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
       CAPITALIZATION
                                                                      ========

            Maximum ratio allowed           %     
                                        ========

================================================================================
COMPUTATION OF FINANCIAL REQUIREMENTS AND RATIOS AS OF ____________
================================================================================

A.     EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO
       (Section 5.3(a)) ($ in 000's)

<TABLE>
          <S>                                                                       <C>    
          (i)  EBITDAX (as defined in Section 5.3(a))

               For the period ended __________ , the sum of the amounts for such
               period of Consolidated net income, Consolidated Interest Expense,
               depreciation expense, depletion expense, amortization expense,
               federal and state income taxes, exploration and abandonment
               expense and other non-cash charges and expenses, all as
               determined on a Consolidated basis for Borrower and its
               Consolidated Subsidiaries;                                            $
                                                                                      ---------

          (ii) CONSOLIDATED INTEREST EXPENSE (as defined in Section 5.3(a))

               For the period ended _________ , total interest expense, whether 
               paid or accrued, of Borrower and its Consolidated Subsidiaries 
               on a Consolidated basis, including, without limitation, all
               commissions, discounts and other fees and charges owed with
               respect to Letters of Credit.                                         $ 
                                                                                      ---------

               CONSOLIDATED INTEREST EXPENSE                                         $              
                                                                                      =========

               EBITDAX TO CONSOLIDATED INTEREST EXPENSE RATIO ((i)(ii))              $              
                                                                                      =========

               Minimum ratio allowed         :1     
                                          ==========
</TABLE>


                               Exhibit J - Page 3


<PAGE>   18


B.       CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
         CAPITALIZATION (Section 5.3(b)) ($ in 000's)

<TABLE>
            <S>                                                                     <C> 
            (i) CONSOLIDATED TOTAL FUNDED DEBT (as defined in Section 1.1)

                (a) All indebtedness of Borrower and its Consolidated
                    Subsidiaries for borrowed money                                  $
                                                                                      ---------

                (b) Plus indebtedness of Borrower and its Consolidated
                    Subsidiaries constituting an obligation to pay the deferred
                    purchase price of property or services (other than customary
                    payment terms taken in the ordinary course of the business)      $
                                                                                      ---------

                (c) Plus indebtedness of Borrower and its Consolidated
                    Subsidiaries evidenced by a bond, debenture, note or similar
                    instrument                                                       $
                                                                                      ---------

                (d) Plus principal obligations under leases capitalized in
                    accordance with GAAP under which either Borrower or any of
                    its Consolidated Subsidiaries is the lessee                      $
                                                                                      ---------

                (e) Plus indebtedness or obligations of the type described in
                    clauses (a), (b), (c) or (d) of the definition of Debt,
                    which are secured by a Lien on any property owned by
                    Borrower or any of its Consolidated Subsidiaries, whether or
                    not such indebtedness or obligations have been assumed by
                    Borrower or any of its Consolidated Subsidiaries (limited
                    however to the lesser of (1) the amount of its liability or
                    (2) the value of such property) (excluding Debt of the type
                    referred to in clause (e) of the definition of "Debt")           $
                                                                                      ---------

                (f) Plus the undischarged balance of any production payment
                    created by Borrower or any of its Consolidated Subsidiaries
                    or for the creation of which Borrower or its Consolidated
                    Subsidiaries directly or indirectly received payment.            $
                                                                                      ---------

                CONSOLIDATED TOTAL FUNDED DEBT                                       $             
                                                                                      =========
</TABLE>


                               Exhibit J - Page 4


<PAGE>   19


<TABLE>
<S>        <C>                                                                      <C>
           (ii) TOTAL CAPITALIZATION (as defined in Section 1.1)
                (a) Consolidated Total Funded Debt of the Borrower and its
                    Consolidated Subsidiaries (See B(i) above)                       $
                                                                                      ---------

                (b) Plus Consolidated shareholders' equity of the Borrower and
                    its Consolidated Subsidiaries                                    $
                                                                                      ---------

                TOTAL CAPITALIZATION                                                 $             
                                                                                      =========

CONSOLIDATED TOTAL FUNDED DEBT TO TOTAL
CAPITALIZATION((i)/(ii))                                                                       %
                                                                                      =========

                Maximum ratio allowed                                                          %     
                                                                                      =========
</TABLE>



                               Exhibit J - Page 5


                                       
<PAGE>   20

                                   Schedule 1

              Schedule of Lenders' Commitments and Percentage Share

<TABLE>
<CAPTION>
                Lenders                              Commitment                  Percentage Share
                -------                              ----------                  ----------------
<S>                                                 <C>                         <C>               
NationsBank, N.A.                                   $8,636,363.64               8.636363636363640%

CIBC Inc.                                           $8,636,363.64               8.636363636363640%

Morgan Guaranty Trust Company of New                $8,636,363.64               8.636363636363640%
York

The Chase Manhattan Bank                            $8,636,363.64               8.636363636363640%

Bank of America National Trust and                  $5,454,545.45               5.454545454545450%
Savings Association

The Bank of New York                                $5,454,545.45               5.454545454545450%

The Bank of Nova Scotia                             $5,454,545.45               5.454545454545450%

Royal Bank of Canada                                $5,454,545.45               5.454545454545450%

Union Bank of California, N.A.                      $5,454,545.45               5.454545454545450%

Wells Fargo Bank, N.A.                              $5,454,545.45               5.454545454545450%

The Fuji Bank, Limited - Houston Agency             $5,454,545.45               5.454545454545450%

Den Norske Bank ASA                                 $3,636,363.64               3.636363636363640%

Banque Paribas                                      $3,636,363.64               3.636363636363640%

First Union National Bank                           $3,636,363.64               3.636363636363640%

Bankers Trust Company                               $1,818,181.82               1.818181818181820%

Credit Agricole Indosuez                            $1,818,181.82               1.818181818181820%

Natexis Banque                                      $1,818,181.82               1.818181818181820%

Toronto Dominion (Texas), Inc.                      $1,818,181.82               1.818181818181820%

The Toyo Trust & Banking Co., Ltd.                  $1,818,181.82               1.818181818181820%

Wachovia Bank, N.A.                                 $1,818,181.82               1.818181818181820%

The Dai-Ichi Kangyo Bank, Ltd., New                 $1,818,181.82               1.818181818181820%
York Branch

The Sanwa Bank, Limited                             $1,818,181.82               1.818181818181820%

KBC Bank N.V.                                       $1,818,181.82               1.818181818181820%
                                                  ===============================================
Totals:                                           $100,000,000.00             100.000000000000000%


                               Schedule 1 - Page 1
</TABLE>





<PAGE>   1

                                                                   EXHIBIT 10.34


                                                                  Execution Copy

                            FIRST AMENDING AGREEMENT

                THIS FIRST AMENDING AGREEMENT dated June 29, 1998



BETWEEN:

                      PIONEER NATURAL RESOURCES CANADA INC.

                                     - and -

                               THE LENDERS HERETO

                                     - and -

                       CANADIAN IMPERIAL BANK OF COMMERCE


PREAMBLE:

                  The parties hereto are parties to the Credit Agreement dated
as of December 18, 1997 (the "Credit Agreement") and wish to amend the Credit
Agreement to reflect changes to the credit established thereunder.

                  NOW THEREFORE in consideration of the covenants and agreements
between the parties contained in this First Amending Agreement and other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as follows:

1.       INTERPRETATION

         In this First Amending Agreement, capitalized terms which are not
otherwise defined herein shall have the meaning given in the Credit Agreement.

2.       AMENDMENTS

         The Credit Agreement is hereby amended as follows:

         (a)      Section 3.12(a) is deleted and replaced with the following:

                  (a)   INTEREST AND FEES. Interest payable by the Borrower
                        under each Accommodation shall be determined in the
                        following manner:

                        (i)   each Canadian Prime Rate Loan shall bear
                              interest at a variable rate of interest per annum
                              equal to the Canadian Prime Rate;



<PAGE>   2


                                      - 2 -

                                                                  Execution Copy

                        (ii)    each U.S. Base Rate Loan shall bear interest at
                                a variable rate per annum equal to the U.S. Base
                                Rate;

                        (iii)   each Alternate Base Rate Loan shall bear
                                interest at a variable rate of interest per
                                annum equal to the Alternate Base Rate;

                        (iv)    each LIBOR Based Loan shall bear interest at a
                                rate per annum equal to the sum of: (i) LIBOR,
                                plus (ii) the applicable Commitment Utilization
                                Margin, plus (iii) the applicable margin based
                                on the Applicable Rating Level as indicated in
                                the table below;

                        (v)     each Canadian Eurodollar Loan shall bear
                                interest at a rate per annum equal to the sum
                                of: (i) the Canadian Eurodollar Rate, plus (ii)
                                the applicable Commitment Utilization Margin,
                                plus (iii) the applicable margin based on the
                                Applicable Rating Level as indicated on the
                                table below; and

                        (vi)    for each Bankers' Acceptance, the stamping fee
                                payable by the Borrower on the acceptance
                                thereof by the Canadian Resident Lenders shall
                                be based on the sum of: (i) the applicable
                                Commitment Utilization Margin, plus (ii) the
                                applicable margin based on the Applicable Rating
                                Level as indicated in the table below.

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------
Applicable Rating Level         I        II        III        IV          V
- --------------------------------------------------------------------------------
<S>                             <C>      <C>       <C>        <C>        <C>
Stamping fee on Bankers'        18       20        23         36         45
Acceptances and margins
  on LIBOR Based
  Loans/Canadian
Eurodollar Loans (Basis
      Points)
- --------------------------------------------------------------------------------
</TABLE>

           (b)  Section 13.1 is amended with the addition of the following as
                Section 13.1(r):

                (r)     YEAR 2000 COMPLIANCE

                        (i)   In this Section 13.1(r):



<PAGE>   3


                                      - 3 -

                                                                  Execution Copy

                                "YEAR 2000 PROBLEM" means the risk that computer
                                applications used by the Borrower or any of its
                                Subsidiaries (or its suppliers and vendors) may
                                be unable to recognize and perform properly
                                date- sensitive functions involving certain
                                dates prior to, and any date after, December 31,
                                1999; and

                                "YEAR 2000 COMPLIANT" means that all computer
                                applications will on a timely basis be able to
                                perform properly date-sensitive functions for
                                all dates before and after January 1, 2000.

                        (ii)    The Borrower has: (i) initiated a review
                                and assessment of all areas within its and each
                                of its Subsidiaries' business and operations
                                (including those affected by suppliers and
                                vendors) that could be adversely affected by the
                                Year 2000 Problem, (ii) developed a plan and
                                time line for addressing the Year 2000 Problem
                                on a timely basis, and (iii) to date,
                                implemented that plan in accordance with that
                                time table. The Borrower reasonably believes
                                that all computer applications (including those
                                of its suppliers and vendors) that are material
                                to its or any of its Subsidiaries' business and
                                operations will be Year 2000 Compliant, except
                                to the extent that a failure to do so could not
                                reasonably be expected to have a Material
                                Adverse Effect.

           (c)  Section 14.1 is amended with the addition of the following as
                14.1(n):

                (n)     YEAR 2000 COMPLIANCE. The Borrower will promptly notify
                        the Agent in the event the Borrower discovers or
                        determines that any computer application (including
                        those of its suppliers and vendors) that is material to
                        its or any of its Subsidiaries' business and operations
                        will not be Year 2000 Compliant on a timely basis,
                        except to the extent that such failure could not
                        reasonably be expected to have a Material Adverse
                        Effect.

           (d)  Schedule "A" is amended with the addition of the following
                definitions in appropriate alphabetical order:

                "Commitment Utilization" means, for any period, the ratio of:
                (i) the Outstandings to (ii) the Commitment Amount, provided
                that for purposes of determining the Commitment Utilization
                Margin for the period ending June 30, 1999, the Commitment
                Utilization is deemed to be ">.50".



<PAGE>   4


                                      - 4 -

                                                                  Execution Copy

                  "COMMITMENT UTILIZATION LEVEL" means the level set forth below
                  that corresponds to the lowest of the ratings issued from time
                  to time by Moody's and S&P, as applicable, for the Parent's
                  senior unsecured long-term debt:

<TABLE>
<CAPTION>
================================================================================
                      Moody's                  S&P
- --------------------------------------------------------------------------------
<S>                   <C>                              
Level A            Baa3 or better        BBB- or better
Level B            Less than Baa3        Less than BBB-
================================================================================
</TABLE>


                  For example, if the Moody's rating is Ba1 and the S&P rating
                  is BBB, Level B shall apply. For purposes of the foregoing,
                  (i) if ratings for the Parent's senior unsecured long-term
                  debt shall not be available from S&P or Moody's, Level B shall
                  be deemed applicable; and (ii) if any of the Rating Agencies
                  shall change its ratings nomenclature prior to the date all
                  Obligations have been paid and the Commitments cancelled, the
                  Parent and the Lenders shall negotiate in good faith to amend
                  the reference to specific ratings in this definition to
                  reflect such change, and pending such amendment, if an
                  appropriate Commitment Utilization Level is otherwise not
                  determinable based upon the foregoing grid, the last
                  Commitment Utilization Level in effect at the time of such
                  change shall continue to apply.

                  "Commitment Utilization Margin" means, on any date, the number
                  of Basis Points per annum set forth below based on the
                  Commitment Utilization Level on such date:



<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------
                               Commitment Utilization Margin
- --------------------------------------------------------------------------------
   Commitment                  Commitment Utilization           Commitment
Utilization Level              is "< or equal to .50"      Utilization is ">.50"
- --------------------------------------------------------------------------------
<S>                            <C>                         <C>    
    Level A                            0 b.p.                     5.0 b.p
- --------------------------------------------------------------------------------
    Level B                            0 b.p.                    10.0 b.p
- --------------------------------------------------------------------------------
</TABLE>


                "Year 2000 Compliant" has the meaning attributed to it in
                Section 13.1(r) of the Agreement.

                "Year 2000 Problem" has the meaning attributed to it in Section
                13.1(r) of the Agreement.

3. Representations and Warranties. To confirm each Lender's understanding
concerning the Borrower and its businesses, properties and obligations, and to
induce the Agent and each Lender to enter into this First Amending Agreement,
the Borrower hereby reaffirms to the Agent and each Lender that, as of the date
hereof, its representations and warranties contained in Section




<PAGE>   5


                                      - 5 -

                                                                  Execution Copy

13.1 of the Credit Agreement (as amended by this First Amending Agreement) and
in the Documents to which it is a party (except to the extent such
representations and warranties relate solely to an earlier date) are true and
correct and additionally represents and warrants as follows:

        (a)     The execution and delivery of this First Amending Agreement and
                the performance by the Borrower and the Restricted Subsidiaries
                of their respective obligations under this First Amending
                Agreement, the Credit Agreement and the other Documents, as
                amended hereby, are within the Borrower's or such Restrictive
                Subsidiaries' corporate powers, have been duly authorized by all
                necessary corporate action, have received all necessary
                governmental approval (if any shall be required), and do not and
                will not contravene or conflict with any provision of Law or of
                the Borrower's or such Restrictive Subsidiaries' constating
                documents or by-laws or of any Law or material agreement,
                judgment, license, order or permit applicable to or binding upon
                such Borrower or Restrictive Subsidiary.

        (b)     This First Amending Agreement and the Credit Agreement, as
                amended hereby, are, and the other Documents when fully executed
                and delivered will be, legal, valid and binding obligations of
                the Borrower and each Restrictive Subsidiary which is a party
                hereto or thereto, enforceable in accordance with their terms
                except as such enforcement may be limited by applicable
                bankruptcy, insolvency, reorganization, winding-up, moratorium
                or similar Laws relating to the enforcement of creditors' rights
                generally and by general principles of equity.


4. Conditions to Effectiveness. The effectiveness of this First Amending
Agreement is conditional upon the following:

        (a)     The Borrower shall pay, or cause the payment, to the Agent for
                the account of each Lender a non-refundable amendment fee
                determined by applying the amendment fee rate of 15 Basis Points
                to the Commitments (whether used or unused) as of the date of
                this First Amending Agreement. Such amendment fee shall be
                allocated among the Lenders based on their Pro-Rata Shares; and

        (b)     The Borrower shall deliver such other documents or items that
                the Agent may reasonably request in a form and substance
                reasonably satisfactory to the Agent.

5. Effective Date. The amendments contained herein shall be effective as of the
date of this First Amending Agreement.

6. Continuing Effect. Each of the parties hereto acknowledges and agrees that
the Credit Agreement, as amended by this First Amending Agreement, the Support
Guarantees and the Parent Guarantee each dated as of December 18, 1997 delivered
to the Agent and Lenders, shall be and continue in full force and effect and are
hereby confirmed and the rights and obligations




<PAGE>   6


                                      - 6 -

                                                                  Execution Copy

of all parties thereunder shall not be affected or prejudiced in any manner
except as specifically provided for herein.

7. Counterparts. This First Amending Agreement may be executed in any number of
counterparts, each of which when executed and delivered shall be deemed to be an
original, but all of which when taken together constitute one and the same
instrument; any party may execute this First Amending Agreement by signing any
counterpart of it.

         IN WITNESS WHEREOF, the Parties have caused this First Amending
Agreement to be duly executed by their respective authorized officers as of the
day and year first above written.


                                     PIONEER NATURAL RESOURCES CANADA INC., 
                                     as Borrower

                                     By: /s/ Jane Stevenson
                                        ----------------------------------------
                                     Name:   Jane Stevenson
                                     Title:  Controller


                                     CANADIAN IMPERIAL BANK OF COMMERCE, 
                                     as Canadian Resident Lender and
                                     Administrative Agent


                                     By: /s/ David Swain
                                        ----------------------------------------
                                     Name:   David Swain
                                     Title:  Vice President

                                     By: /s/ James Chepyha
                                        ----------------------------------------
                                     Name:   James Chepyha
                                     Title:  Executive Director

                                     Address:
                                     Bankers Hall, 10th floor
                                     855-2nd Street S.W.
                                     Calgary, Alberta  T2P 4J7
                                     Fax: 403-221-5779



      This is a counterpart execution page to the First Amending Agreement
dated June 29, 1998.





<PAGE>   7


                                      - 7 -

                                                                  Execution Copy

                                     THE BANK OF NOVA SCOTIA, 
                                     as Canadian Resident Lender


                                     By: /s/ Dan Belot
                                        ----------------------------------------
                                     Name:   Dan Belot
                                     Title:  Relationship Manager

                                     By: /s/ Michael Jackson
                                        ----------------------------------------
                                     Name:   Michael Jackson
                                     Title:  Vice President and Office Head

                                     Address:
                                     Corporate & Energy Banking
                                     Suite 3820, 700-2nd Street S.W.
                                     Calgary, Alberta  T2P 2N7
                                     Fax:  403-221-6497


                                     ROYAL BANK OF CANADA,
                                     as Canadian Resident Lender

                                     By: /s/ Bruce Edgelow                    
                                        ----------------------------------------
                                     Name:   Bruce Edgelow
                                     Title:  Senior Account Manager


                                     By: /s/ Lorne Gartner                    
                                        ----------------------------------------
                                     Name:   Lorne Gartner
                                     Title:  Manager

                                     Address:
                                     Oil & Gas Banking Centre
                                     335 8th Avenue S.W., 11th floor,
                                     Calgary, Alberta  T2P 1C9
                                     Fax:  403-292-3436



             This is a counterpart execution page to the First Amending
Agreement dated June 29, 1998.



<PAGE>   8


                                      - 8 -

                                                                  Execution Copy

                                     THE CHASE MANHATTAN BANK OF CANADA, 
                                     as Canadian Resident Lender

                                     By: /s/ Christine Chan
                                        ----------------------------------------
                                     Name:   Christine Chan
                                     Title:  Vice President

                                     Address:
                                     1 First Canadian Place
                                     6900, 100 King Street West
                                     Toronto, Ontario  M5X  1A4
                                     Fax:  416-216-4161


                                     MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                                     as Non-resident Lender

                                     By: /s/ John Kowalczuk
                                        ----------------------------------------
                                     Name:   John Kowalczuk
                                     Title:  Vice President

                                     Address:
                                     60 Wall Street, 22nd floor
                                     New York, New York  10260
                                     Fax:  212-648-5014


                                     NATIONSBANK, N.A.,
                                     successor-by-merger to NationsBank of
                                     Texas, N.A. as Non-resident Lender

                                     By: /s/ Frank Stowers
                                        ----------------------------------------
                                     Name:   Frank Stowers
                                     Title:  Vice President

                                     Address:
                                     303 West Wall Street
                                     Midland, Texas  79701
                                     Fax:  915-685-2009



             This is a counterpart execution page to the First Amending
Agreement dated June 29, 1998.


<PAGE>   9
 

                                      - 9 -

                                                                  Execution Copy

                                     THE TORONTO-DOMINION BANK, 
                                     as Canadian Resident Lender

                                     By: /s/ Loretta Palandri
                                        ----------------------------------------
                                     Name:   Loretta Palandri
                                     Title:  Manager, Corporate Banking

                                     Address:
                                     800 Home Oil Tower
                                     324-8th Avenue S.W.
                                     Calgary, Alberta  T2P 2Z2
                                     Fax:  403-292-2772


                                     FIRST UNION NATIONAL BANK,
                                     as Non-resident Lender

                                     By: /s/ Michael Kolosowsky
                                        ----------------------------------------
                                     Name:   Michael Kolosowsky
                                     Title:  Vice President

                                     Address:
                                     One First Union Center
                                     301 South College Street, TW-11
                                     Charlotte, North Carolina  28288-0658
                                     Fax:  704-374-6249


                                     WACHOVIA BANK, N.A., 
                                     as Non-resident Lender

                                     By: /s/ Paige Mesaros
                                        ----------------------------------------
                                     Name:   Paige Mesaros
                                     Title:  Vice President

                                     Address:
                                     191 Peachtree Street N.E.
                                     MC370, 28th floor
                                     Atlanta, Georgia  30303
                                     Fax:  404-332-6898





             This is a counterpart execution page to the First Amending
Agreement dated June 29, 1998.









<PAGE>   1
                                                                 EXHIBIT 10.42

                                 AMENDMENT NO. 1

                                       TO

                        PIONEER NATURAL RESOURCES COMPANY

                          EMPLOYEE STOCK PURCHASE PLAN


         AMENDMENT NO. 1 (this "Amendment") to that certain Employee Stock
Purchase Plan (the "Plan") of Pioneer Natural Resources Company (the "Company")
executed August 7, 1997.

                                    RECITALS

         WHEREAS, the Company has adopted the Plan; and

         WHEREAS, the Board of Directors of the Company, acting through the
Compensation Committee of the Board of Directors of the Company (which
administers the Plan), has authorized amendments to the Plan, which amendments
are memorialized below in this Amendment.

         NOW, THEREFORE, the Plan is hereby amended as follows:

                  1.    Amendment of subparagraph 7(b). The first sentence of
subparagraph 7(b) of the Plan is hereby amended in its entirety to read as
follows:

                  "The option price per share of Stock to be paid by each
                  Eligible Employee on each exercise of his option shall be an
                  amount equal to 85% of the Fair Market Value of the Stock on
                  the date of exercise."

                  2.    Amendment of subparagraph 12(c). Subparagraph 12(c) of 
the Plan is hereby amended in its entirety to read as follows:

                        "(c) CHANGE OF CONTROL DEFINED. For purposes of
                  subparagraph 12(b) of the Plan, a "Change of Control" shall
                  have occurred if (and only if) a "Change in Control" occurs
                  under the Company's Long-Term Incentive Plan dated August 7,
                  1997, or under any successor plan to such Long-Term Incentive
                  Plan, as any such plan may from time to time be amended."

                  3. Confirmation of the Plan. Except as to the extent modified
by this Amendment, the Plan is hereby ratified and confirmed in all respects.


                                        1
<PAGE>   2

         IN WITNESS WHEREOF, the Company has caused this Amendment to be
executed by its duly authorized officer as of this 9th day of December, 1998.


                                        PIONEER NATURAL RESOURCES COMPANY



                                        By:      /s/ Larry N. Paulsen
                                                 -----------------------------
                                        Name:    Larry N. Paulsen
                                        Title:   Vice President--Administration
                                                 and Risk Management


                                       2

<PAGE>   1
                                                                   EXHIBIT 10.69



                            [PRIMARY CREDIT FACILITY]
================================================================================

              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

                                  by and among

                       PIONEER NATURAL RESOURCES COMPANY,
                                  as BORROWER,

                                       and

                               NATIONSBANK, N.A.,
                            as ADMINISTRATIVE AGENT,

                                       and

                                   CIBC INC.,
                             as DOCUMENTATION AGENT,

                                       and

                   MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                             as DOCUMENTATION AGENT,

                                       and

                   CHASE BANK OF TEXAS, NATIONAL ASSOCIATION,
                              as SYNDICATION AGENT,

                         THE CO-AGENTS SIGNATORY HERETO,

                                       and

                       THE OTHER LENDERS SIGNATORY HERETO

                           Dated as of March 19, 1999

                              ---------------------

                     NATIONSBANC MONTGOMERY SECURITIES LLC,
                        as LEAD ARRANGER and BOOK MANAGER

================================================================================


<PAGE>   2




              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

         THIS SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT (herein
called this "Amendment and Restatement"), is made as of March 19, 1999, by and
among PIONEER NATURAL RESOURCES COMPANY, a Delaware corporation (the
"Borrower"), NATIONSBANK, N.A., as successor-by-merger to NationsBank of Texas,
N.A., as Administrative Agent and Collateral Agent, CIBC INC., as Documentation
Agent, MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation Agent, CHASE
BANK OF TEXAS, NATIONAL ASSOCIATION, as successor-in-interest to The Chase
Manhattan Bank, as Syndication Agent, the "Co-Agents" party to the Credit
Agreement (as herein defined), and the other Lenders from time to time parties
to the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co- Agents have heretofore entered into a certain Amended and
Restated Credit Facility Agreement - Primary Credit Facility, dated as of
December 18, 1997, as previously amended (herein the "Credit Agreement"); and

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co- Agents now intend to amend and restate the Credit Agreement;
and

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, each of the Borrower, the Lenders, the Managing
Agents, the Collateral Agent and the Co-Agents hereby agree as follows:

         SECTION 1. Defined Terms. All capitalized terms used but not otherwise
defined herein shall have the meanings given in the Credit Agreement, as amended
and restated by the Amendment and Restatement.

         SECTION 2. Amendments to Credit Agreement. Effective as of Effective
Date, the Credit Agreement is hereby amended and restated in its current form
with the following amendments:

         a.             The definitions of "Amendment Fee Rate", "Applicable 
                  Rating Level", "Consolidated Interest Expense", "EBITDAX",
                  "Eurodollar Margin" and "Facility Fee Rate" in Section 1.1 of
                  the Credit Agreement are hereby amended and restated to read
                  in their entirety as follows:

         "        "Amendment Fee Rate" means 37.5 basis points."

         "        "Applicable Rating Level" means the level set forth below that
         corresponds to the lowest of ratings issued from time to time by
         Moody's and S&P, as applicable to Borrower's senior, unsecured 
         long-term debt:



<PAGE>   3


<TABLE>
<CAPTION>

=======================================================
                        Moody's                S&P
- -------------------------------------------------------
<S>                     <C>                 <C> 
Level I                 >= Baa3             >= BBB-
- -------------------------------------------------------
Level II                   Ba1                 BB+
- -------------------------------------------------------
Level III                  Ba2                 BB
- -------------------------------------------------------
Level IV                <= Ba3              <= BB-
=======================================================
</TABLE>

         For example, if the Moody's rating is Ba1 and the S&P rating is BB,
         Level III shall apply.

                  For purposes of the foregoing, (i) ">=" means a rating more
         favorable than or equal to; "<=" means a rating less favorable than or
         equal to; (ii) if ratings for Borrower's senior unsecured long-term
         debt shall not be available from S&P or Moody's, Level IV shall be
         deemed applicable; (iii) if any of the Rating Agencies shall change its
         ratings nomenclature prior to the date all Obligations have been paid
         and the Commitments canceled, Borrower and the Lenders shall negotiate
         in good faith to amend the references to specific ratings in this
         definition to reflect such change, and pending such amendment, if an
         appropriate Applicable Rating Level is otherwise not determinable based
         upon the foregoing grid, the last Applicable Rating Level in effect at
         the time of such change shall continue to apply."

         "        "Consolidated Interest Expense" means, for any period, total
         interest expense, whether paid or accrued, of Borrower and its
         Subsidiaries on a Consolidated basis, including, without limitation,
         all commissions, discounts and other fees and charges owed with respect
         to Letters of Credit."

         "        "EBITDAX" means, for any period the sum of the amounts for 
         such period of Consolidated net income (excluding gains and losses on
         the sale of assets), Consolidated Interest Expense, depreciation
         expense, depletion expense, amortization expense, federal and state
         income taxes, exploration and abandonment expense and other non-cash
         charges and expenses, all as determined on a Consolidated basis for
         Borrower and its Subsidiaries.

         "        "Eurodollar Margin" means, on any date, with respect to each
         Eurodollar Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the number of basis points per annum set
         forth below based on the Applicable Rating Level and the applicable
         Total Leverage Ratio:

<TABLE>
<CAPTION>
================================================================================
                                      Total Leverage Ratio
- --------------------------------------------------------------------------------
Applicable                               3.0 < "x" <= 4.0
Rating Level            "x" <= 3.0                    ---        "x" > 4.0
- --------------------------------------------------------------------------------
<S>                     <C>                  <C>                 <C>       
   Level I              112.5 b.p.           125.0 b.p.          150.0 b.p.
- --------------------------------------------------------------------------------
   Level II             137.5 b.p.           150.0 b.p.          200.0 b.p.
- --------------------------------------------------------------------------------
   Level III            162.5 b.p.           187.5 b.p.          225.0 b.p.
- --------------------------------------------------------------------------------
   Level IV             200.0 b.p.           225 b.p.            250.0 b.p.
- --------------------------------------------------------------------------------
</TABLE>



                                       2
<PAGE>   4

         Changes in the Eurodollar Margin will occur automatically without prior
         notice (x) upon the effectiveness of any change of the Applicable
         Rating Level and (y) three (3) days following the earlier of (A) the
         date the Borrower delivers the certificate in respect of the previous
         Fiscal Quarter required pursuant to the second sentence of Subsection
         5.1(b)(1) (provided that for purposes of this definition, the Borrower
         shall be permitted to deliver a certificate sixty (60) days following a
         Fiscal Year containing the information to be included in the
         certificate to be delivered pursuant to Section 5.1(b)(1) except based
         upon unaudited financial statements for such Fiscal Year) or 5.1(b)(2),
         as the case may be and (B) sixty (60) days following the end of such
         previous Fiscal Quarter in the event of a change in the Total Leverage
         Ratio; provided that so long as the Debt Reduction Requirement is not
         satisfied, the Eurodollar Margin shall be based on a Total Leverage
         Ratio of greater than 4.0 to 1.0. Administrative Agent will give notice
         promptly to Borrower and the Lenders of changes in the Eurodollar
         Margin."

         "        "Facility Fee Rate" means, on any date that a facility fee is
         due pursuant to Section 2.7, the number of basis points per annum set
         forth below based on the Applicable Rating Level on such date;
         provided, that notwithstanding the provisions of Section 2.7, the
         facility fee payable to each Lender at the Facility Fee Rate pursuant
         to Section 2.7 for any period shall be payable on the average daily
         unused amount (which amount shall include any outstanding Swing Line
         Advances or Competitive Bid Advances) of such Lender's Percentage Share
         of the Facility Amount for such period:

<TABLE>
<CAPTION>
                ====================================================
                     Applicable               Facility Fee Rate
                    Rating Level                    Margin
                ----------------------------------------------------
<S>                                                <C>      
                       Level I                     37.5 b.p.
                ----------------------------------------------------
                       Level II                    50.0 b.p.
                ----------------------------------------------------
                       Level III                   50.0 b.p.
                ----------------------------------------------------
                       Level IV                    50.0 b.p.
                ====================================================
</TABLE>


         Changes in the Facility Fee Rate will occur automatically without prior
         notice. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Facility Fee Rate."

         b.            Section 1.1 of the Credit Agreement is hereby amended by
                  inserting the following definitions of "Base Rate Margin",
                  "Consolidated Tangible Net Worth", " Debt Issuance", "Debt
                  Reduction Requirement", "Engineering Report", "Initial
                  Engineering Report", "Net Cash Proceeds", "Non-Recourse Debt",
                  "Properties", "Properties NPV", "Properties NPV to Total Debt
                  Ratio", "Public Notes", "Qualified Investments", "Security
                  Documents", "Senior Debt", "Senior Debt Margin", "Senior
                  Leverage Ratio", "Subordinated Debt" and "Total Leverage
                  Ratio" in appropriate alphabetical order:




                                       3
<PAGE>   5





         "        "Base Rate Margin" means, on any date, with respect to each 
         Base Rate Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the greater of (A) the Eurodollar Margin
         less 125 basis points or (B) zero."

         "        "Consolidated Tangible Net Worth" means (i) the Consolidated
         shareholder's equity of Borrower and its Subsidiaries (determined in
         accordance with GAAP), less (ii) the amount of Consolidated intangible
         assets of Borrower and its Subsidiaries, plus (iii) the aggregate
         amount of any non-cash write downs under Financial Accounting Standards
         19, 109 and 121, on a consolidated basis, by Borrower and its
         Subsidiaries after December 31, 1998."

         "        "Debt Issuance" means the sale or issuance after February 1, 
         1999, by Borrower or any Restricted Person of notes or other debt
         securities for cash pursuant to a registration statement under the
         Securities Act of 1933, as amended (the "Act"), or to qualified
         institutional buyers in reliance on Rule 144A under the Act or pursuant
         to a transaction effected as private placement pursuant to an exemption
         to registration under the Act."

         "        "Debt Reduction Requirement" means that all of the following
         requirements shall have occurred (i) the expiration or termination in
         full of the commitments under, and the payment of all amounts under or
         in respect of, the 364 Day Facility, (ii) the reduction of the
         Commitments under this Agreement after February 1, 1999 by an aggregate
         amount of at least $325,000,000 and the payment of all Consolidated
         Total Funded Debt required to be paid as the result of such reduction
         and (iii) the maintenance of the Total Leverage Ratio at less than or
         equal to 4.25 to 1.00 for at least two consecutive Fiscal Quarters ,
         except that solely for purposes of Subsection 2.9(g) hereof,
         satisfaction of the Debt Reduction Requirement shall be determined
         using the following clause (iii) in lieu of the foregoing clause (iii):
         (iii) on the day on which the determination is made and after giving
         pro forma effect to any transaction occurring on such day (including
         repayment of Obligations to be made on such day) the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX for the four (4) Fiscal Quarters most recently ended prior to
         such day is less than or equal to 4.25 to 1, after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such most recently ended four Fiscal
         Quarters as if such assets or Property had been sold or acquired at the
         beginning of such four most recently ended Fiscal Quarters; provided
         that for purposes of the calculation in this clause (iii) for purposes
         solely of Section 2.9(g) hereof, (1) EBITDAX for the four Fiscal
         Quarters ending December 31, 1998 shall be deemed to be four times the
         EBITDAX for the Fiscal Quarter ending on such date after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such Fiscal Quarter as if such assets
         or Property had been sold or acquired at the beginning of such Fiscal
         Quarter, (2) EBITDAX for the four Fiscal Quarters ending March 31, 1999
         shall be deemed to be two times the EBITDAX for the semi-annual period
         ending on such date after adjusting such EBITDAX on a pro forma basis
         for any assets or Property sold or acquired after the beginning of such
         semi-annual period ending on such date as if such assets or Property
         had been sold or acquired at the 




                                       4
<PAGE>   6

         beginning of such semi-annual period ending on such date and (3)
         EBITDAX for the four Fiscal Quarters ending June 30, 1999 shall be
         deemed to be the product of 4/3rds times EBITDAX for the three Fiscal
         Quarters ending on such date after adjusting such EBITDAX on a pro
         forma basis for any assets or Property sold or acquired after the
         beginning of such three Fiscal Quarters as if such assets or Property
         had been sold or acquired at the beginning of such three Fiscal
         Quarters."

         "        "Engineering Report" means the Initial Engineering Report and
         each other engineering report delivered pursuant to Section 5.1(b)(4)."

         "        "Initial Engineering Report" means that certain engineering 
         report, delivered to the Administrative Agent on February 26, 1999
         concerning the Properties."

         "        "Net Cash Proceeds" means the cash or cash equivalent proceeds
         received by the Borrower or any Restricted Person as a result of (i) an
         issuance of common stock, preferred stock or other equity of the
         Borrower or any Restricted Person, (ii) a Debt Issuance, or (iii) a
         sale of Property of Borrower or any Restricted Person, in each case
         after deducting all of the following, as applicable, (a) legal fees
         paid or reimbursed by Borrower or any Restricted Person and allocable
         to such transaction, (b) underwriters' discounts, initial purchasers'
         discounts, placement agent's fees, brokers' commissions and other
         discounts, commissions or fees incurred in connection with such
         transaction, to the extent paid or reimbursed by Borrower or any
         Restricted Person, (c) registration fees, printer's fees and other
         costs of sale paid or reimbursed by Borrower or any Restricted Person
         in connection with such transaction, and (d) any reserves maintained by
         Borrower or any Restricted Person for any closing cost adjustments or
         similar contingencies in connection with such transaction. Proceeds of
         any such transaction consisting of notes, stock, securities or other
         non-cash assets or property shall not be included as Net Cash Proceeds;
         provided, however, any cash or cash equivalents received as a result of
         the sale, pledge or transfer of any such note, stock, securities or
         other non-cash assets or property or as a payment on account of or
         otherwise realized on account of principal or capital of any note,
         stock, securities or other non-cash assets or property (but not
         dividends, interest or operating income in respect of any assets or
         property) shall be treated as cash or cash equivalent proceeds received
         by Borrower or a Restricted Person at the time such cash or cash
         equivalent is received by Borrower or any Restricted Person."

         "        "Properties" means, at the particular time in question, all 
         material oil and gas properties and reserves (which properties and
         reserves shall be free of any Liens other than Permitted Liens) of the
         Borrower and the Subsidiaries at such time and that were evaluated in
         the Initial Engineering Report or, if applicable, the Engineering
         Report and other information most recently provided by Borrower
         pursuant to Section 5.1(b)(4)."

         "        "Properties NPV" means, at the particular time in question, 
         the net present value of the Borrower's and the Subsidiaries' proved
         reserves included in the Properties set forth in either (i) the Initial
         Engineering Report or (ii) if applicable, the Engineering Report most
         recently provided by Borrower pursuant to Section 5.1(b)(4)."



                                       5
<PAGE>   7

         "        "Properties NPV to Total Debt Ratio" means at any time the 
         ratio of (a) the Properties NPV to (b) Borrower's Total Debt."

         "        "Public Notes" means each of the following: (i) Borrower's
         $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's $150,000,000
         8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
         Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes
         due 2028, together with all guaranties thereof and all notes issued
         from time to time in replacement therefor and (v) any other publicly
         tradeable notes, bonds or debentures outstanding as of February 1,
         1999, which notes, bonds or debentures by their terms require that they
         be secured equally and ratably with any collateral under this
         Agreement."

         "        "Qualified Investments" means (i) the purchase by Borrower or
         one of its Subsidiaries of Properties constituting proved reserves, or
         (ii) capital expenditures made by Borrower or one of its Subsidiaries
         to maintain, enhance or develop Properties constituting proved reserves
         owned by Borrower or one of its Subsidiaries."

         "        "Security Documents" means, collectively, the Mortgage, Deed 
         of Trust, Assignment, Security Agreement and Financing Statement from
         the Borrower or any of its Subsidiaries as the case may be, granted to
         a Collateral Agent selected by the Administrative Agent and reasonably
         acceptable to Borrower to secure equally and ratably the Obligations
         and the Public Notes, substantially in the form attached hereto as
         Exhibit Q with appropriate insertions (with any modifications necessary
         to comply with applicable state laws or filing requirements), and any
         and all further documents, financing statements, agreements and
         instruments which may be required under applicable law, or which the
         Agent may reasonably request, in order to satisfy the requirements of
         Section 5.1(n)."

         "        "Senior Debt" means Total Funded Debt of the Borrower and its
         Subsidiaries, other than Total Funded Debt that is Subordinated Debt."

         "        "Senior Debt Margin" means, on any date, the number of basis 
         points per annum set forth below based on the Senior Leverage Ratio on
         such date:
<TABLE>
<CAPTION>
           ====================================================================
               Senior Leverage Ratio              "x" <= 4.25      "x" > 4.25
           --------------------------------------------------------------------
<S>                                                   <C>            <C>      
            On or before August 3, 1999               0 b.p.         25.0 b.p.
           --------------------------------------------------------------------
            After August 3, 1999                      0 b.p.         50.0 b.p.
           ====================================================================
</TABLE>

         Changes in the Senior Debt Margin will occur automatically without
         prior notice three (3) days following the earlier of (A) the date the
         Borrower delivers the certificate in respect of the previous Fiscal
         Quarter required pursuant to the second sentence of Subsection
         5.1(b)(1) (provided that for purposes of this definition, the Borrower
         shall be permitted to deliver a certificate sixty (60) days following a
         Fiscal Year containing the information




                                       6
<PAGE>   8

         to be included in the certificate to be delivered pursuant to Section
         5.1(b)(1) except based upon unaudited financial statements for such
         Fiscal Year) or 5.1(b)(2), as the case may be and (B) sixty (60) days
         following the end of such previous Fiscal Quarter; provided that so
         long as the Debt Reduction Requirement is not satisfied, the Senior
         Debt Margin shall be based on a Senior Leverage Ratio of greater than
         4.25 to 1.0."

         "        "Senior Leverage Ratio" means at any time the ratio of (a) 
         Borrower's then Consolidated Senior Debt to (b) Borrower's EBITDAX;
         provided that for purposes of the foregoing calculation, EBITDAX for
         any Fiscal Quarter shall be deemed to be four times the EBITDAX for
         such Fiscal Quarter."

         "        "Subordinated Debt" means all unsecured Debt of the Borrower 
         for money borrowed which is subordinated in right of payment to the
         payment of all Obligations, upon customary terms satisfactory to the
         Administrative Agent."

         "        "Total Leverage Ratio" means at any time the ratio of (a) 
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX; provided that for purposes of the foregoing calculation,
         EBITDAX for any Fiscal Quarter shall be deemed to be four times the
         EBITDAX for such Fiscal Quarter."

         c.             Section 1.1 of the Credit Agreement is hereby amended by
                  deleting the following definitions of "Commitment
                  Utilization", "Commitment Utilization Level" and
                  "Commitment Utilization Margin" in their entirety.

         d.             The definition of "Debt" in Section 1.1 of the Credit
                  Agreement is hereby amended by adding the following to the end
                  of clause (h) before the semicolon: "and the amount of
                  deferred revenue attributable to any forward sale of
                  production or Properties for which such Person has directly or
                  indirectly received payment in advance."

         e.             Section 2.9 of the Credit Agreement is hereby amended 
                  and restated to read in its entirety as follows:

         "        Section 2.9     Termination and Reduction of Commitments; 
         Mandatory Prepayments.

                  (a) Unless previously terminated, the Commitments shall
         terminate on the Maturity Date.

                  (b) Borrower may at any time terminate, or from time to time
         reduce, the Commitments; provided that (i) each reduction of the
         Commitments shall be in an amount that is an integral multiple of
         $1,000,000 and not less than $5,000,000 and (ii) Borrower shall not
         terminate or reduce the Commitments if, after giving effect to any
         concurrent prepayment of the Loans in accordance with Section 2.10, the
         sum of (i) all Lenders' Revolving Loan Advances (including any
         Revolving Loan Advances to be made but not yet made pursuant to a
         Request for Advance) outstanding at any time plus (ii) the LC




                                       7
<PAGE>   9

         Obligations of all Lenders at such time plus (iii) all Swing Line
         Advances to Borrower plus (iv) all Lenders' Competitive Bid Advances
         outstanding at such time, would exceed the total Commitments.

                  (c) Borrower shall notify the Administrative Agent of any
         election to terminate or reduce the Commitments under paragraph (b) of
         this Section at least two Business Days prior to the effective date of
         such termination or reduction, specifying such election and the
         effective date thereof. Promptly following receipt of any notice, the
         Administrative Agent shall advise the Lenders of the contents thereof.
         Each notice delivered by Borrower pursuant to this Section shall be
         irrevocable; provided that a notice of termination of the Commitments
         delivered by Borrower may state that such notice is conditioned upon
         the effectiveness of other credit facilities, in which case such notice
         may be revoked by Borrower (by notice to the Administrative Agent on or
         prior to the specified effective date) if such condition is not
         satisfied. Any termination or reduction of the Commitments shall be
         permanent.

                  (d) Upon the issuance of Debt permitted pursuant to Section
         5.2(a)(5), (i) the Commitments automatically and permanently shall be
         reduced by, (ii) the Loan Commitments of each Lender automatically and
         permanently shall be reduced on a pro-rata basis in an amount
         sufficient to reduce the aggregate amount of such Loan Commitments by,
         and (iii) the Borrower shall make a mandatory prepayment on the Loans
         on or within ten (10) days of such issuance in, an amount equal to 100%
         of the Net Cash Proceeds received by Borrower in connection with such
         issuance.

                  (e) Upon the issuance of any common stock, preferred stock or
         other equity of the Borrower or any Restricted Subsidiary, (i) the
         Commitments automatically and permanently shall be reduced by, and the
         Loan Commitments of each Lender automatically and permanently shall be
         reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by, an amount equal to 50% of
         the Net Cash Proceeds received by Borrower in connection with such
         issuance and (ii) the Borrower shall make a mandatory prepayment on the
         Loans on or within ten (10) days of such issuance in an amount equal to
         75% of the Net Cash Proceeds received by Borrower in connection with
         such issuance. In addition, unless Borrower provides evidence
         acceptable to the Administrative Agent that the Borrower and its
         Restricted Subsidiaries have made Qualified Investments in an amount of
         at least 25% of the Net Cash Proceeds of such issuance on or within 120
         days after the date of such issuance, then (x) the Commitments
         automatically and permanently shall be reduced by and (y) the Loan
         Commitments of each Lender automatically and permanently shall be
         reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by an amount equal to the
         difference of 25% of the Net Cash Proceeds received by Borrower in
         connection with such issuance minus the amount of such Qualified
         Investments of such proceeds by the Borrower and its Restricted
         Subsidiaries during such 120 day period.





                                       8
<PAGE>   10

                  (f) Upon the sale, transfer, conveyance or assignments of any
         Properties of Borrower or its Restricted Subsidiaries, (i) the
         Commitments automatically and permanently shall be reduced by, and (ii)
         the Loan Commitments of each Lender automatically and permanently shall
         be reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by, 100% of the Net Cash
         Proceeds in excess of $25,000,000 in the aggregate for all such sales
         after February 1, 1999 received by Borrower in connection with such
         sale, transfer, assignment or conveyance and the Borrower shall make
         mandatory prepayments on the Loans on or within ten (10) days of such
         sale, transfer, assignment or conveyance to the extent necessary so
         that after giving effect to such mandatory prepayments the sum of (a)
         all Lenders' Revolving Loan Advances (including any Revolving Loan
         Advances to be made but not yet made pursuant to a Request for Advance)
         outstanding at any time plus (b) the LC Obligations of all Lenders at
         such time plus (c) all Swing Line Advances to Borrower plus (d) all
         Lenders' Competitive Bid Advances outstanding at such time, would not
         exceed the total Commitments.

                  (g) Notwithstanding anything to the contrary contained in this
         Agreement, no reduction in the Commitments or Loan Commitments shall be
         required pursuant to the provisions of paragraphs (d), (e), and (f) of
         this Section 2.9 to the extent that, and so long as, the Borrower has
         satisfied the Debt Reduction Requirement and no Default has occurred
         and is continuing.

                  (h) Notwithstanding any other provision of this Agreement, if
         during the period commencing February 1, 1999 and ending December 31,
         1999 the aggregate reductions in Commitments pursuant to the foregoing
         subsections of this Section 2.9 is less than $325,000,000, on December
         31, 1999 the Commitments shall be automatically reduced by the
         remainder of (i) $325,000,000 minus (ii) the total of all reductions in
         the Commitment pursuant to the foregoing subsections of this Section
         2.9 during such period, and Borrower shall make a mandatory prepayment
         on December 31, 1999 in an amount sufficient to cause the sum of (i)
         all Lenders' Revolving Loan Advances (including any Revolving Loan
         Advances to be made but not yet made pursuant to a Request for Advance)
         outstanding at such time plus (ii) the LC Obligations of all Lenders at
         such time plus (iii) all outstanding Swing Line Advances to Borrower
         plus (iv) all Lenders' Competitive Bid Advances outstanding at such
         time not to exceed the Total Commitments after giving effect to such
         reduction.

                  (i) Each reduction in Commitments pursuant to this Section 2.9
         shall be made ratably among the Lenders in accordance with their
         respective Commitments on the date of such reduction.

                  (j) To the extent that the Canadian Credit Facility contains
         requirements to reduce the Commitment Amount (as defined in the
         Canadian Credit Facility) and the Commitments (as defined in the
         Canadian Credit Facility) and to make prepayments in the circumstances
         described in the foregoing subsections (d), (e) and (f) of this Section
         2.9,




                                       9
<PAGE>   11

         then the percentages 100%, 75% and 25%, respectively, in such
         subsections (d), (e) and (f) shall be deemed reduced to 80%, 60% and
         20%, respectively."

         f.                Section 4.1(h) of the Credit Agreement is hereby 
                  amended by inserting at the end of Section 4.1(h) the 
                  following sentence:

         "There are no statements or conclusions in any Engineering Report which
         are based upon or include misleading information or fail to take into
         account material information regarding the matters reported therein, it
         being understood that (1) each Engineering Report is necessarily based
         upon professional opinions, estimates and projections and (2) Borrower
         does not warrant that such opinions, estimates and projections will
         ultimately prove to have been accurate."

         g.                Section 5.1(b) of the Credit Agreement is hereby 
                  amended by inserting after Section 5.1(b)(3) of the Credit
                  Agreement the following Sections 5.1(b)(4):

         "        (4)      By August 15th and February 15th of each Fiscal Year,
                           an Engineering Report prepared by the Borrower
                           covering all Properties constituting proved reserves
                           as of June 30th and December 31st, respectively, of
                           such Fiscal Year, based upon the Designated Lenders'
                           Assumptions. No later than thirty (30) days prior to
                           the date that an Engineering Report is required to be
                           delivered by Borrower pursuant to this subsection
                           5.1(b)(4), Administrative Agent (i) shall have
                           obtained from each of NationsBank, N.A., CIBC Inc.,
                           Morgan Guaranty Trust Company of New York, and Chase
                           Bank of Texas, National Association, as successor-in-
                           interest to The Chase Manhattan Bank, which is a
                           Lender under this Agreement on such day, each such
                           Lender's assumptions regarding future commodity
                           prices, including, as applicable, annual escalations
                           thereof or average prices for each future year, and
                           such Lender's discount factor for discounting to
                           present value future net revenues in each case as
                           utilized by such Lender in making its normal and
                           customary evaluation of the net present value of oil
                           and gas reserves of its borrowers generally and (ii)
                           shall have determined and provided to the Borrower
                           the average of such future price assumptions and
                           discount factors provided to the Administrative Agent
                           by such Lenders (such average being herein called the
                           "Designated Lenders' Assumptions").

         h.                Section 5.1 of the Credit Agreement is hereby amended
                  by inserting the following Section 5.1(n) after Section 5.1(m)
                  of the Credit Agreement:

         "        (n)      Springing Lien. In the event that (i) any Event of 
         Default has occurred and is continuing or (ii) at any time after August
         3, 1999 the sum of (A) aggregate Commitments under this Agreement plus
         (B) the aggregate "Commitments" under the 364 Day Credit Facility,
         exceeds $775,000,000, then, without affecting in any way any




                                       10
<PAGE>   12

         other rights of the Lenders hereunder, the Administrative Agent, at the
         direction of the Required Lenders, may request that the Borrower, and
         the Borrower agrees to:

                                    (i) duly execute and deliver to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent) the Security Documents and cause each
                  such Security Document to be filed, registered and recorded,
                  as the law may require or the Administrative Agent may
                  request, in each jurisdiction where so required or requested,
                  and deliver to the Administrative Agent an acknowledgment
                  copy, or other evidence satisfactory to it, of each such
                  filing, registration and recordation, in order to mortgage,
                  assign, grant a security interest in and pledge to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent), acting on behalf of the Lenders, all of
                  the Borrower's and the Restricted Subsidiaries' right, title
                  and interest in and to the Properties located in the United
                  States, and the proceeds thereof, having a Properties NPV, as
                  of the date of the most recent Engineering Report, of 80% of
                  the aggregate Properties NPV attributable to Properties
                  located in the United States (the "Collateral") in such
                  request, and to perfect and evidence the first priority of all
                  such Security Documents (subject to liens and encumbrances
                  permitted by the terms of such instruments); provided that the
                  Borrower shall not, and shall not permit any of its
                  Subsidiaries to, on or after the Effective Date enter into any
                  amendment of any such contract or agreement, or enter into any
                  other contract or agreement, that in either case would result
                  in any additional such material consent, authorization or
                  approval requirement; and

                                    (ii) deliver to the Administrative Agent,
                  within 30 days of such request for delivery of the Security
                  Documents (or, if a Person other than the Administrative Agent
                  is to act as collateral agent under the Security Documents, if
                  later, within fifteen (15) days of the designation and
                  acceptance by such Person of the collateral agency), evidence
                  acceptable to the Administrative Agent, in its reasonable
                  discretion, indicating that Security Documents covering 80% of
                  the Properties NPV attributable to the Properties located in
                  the United States have been executed, acknowledged, filed,
                  registered and recorded, as the law may require or the Agent
                  may request, in each jurisdiction where so required or
                  requested.

         Borrower further agrees to execute, or cause its Subsidiaries to
         execute, any and all further documents, financing statements,
         agreements and instruments, and take all further actions (including
         filing Uniform Commercial Code financing statements), which may be
         required under applicable law, or which the Administrative Agent may
         reasonably request, in order to effectuate the transactions
         contemplated by this Section 5.1(n) and in order to grant, preserve,
         protect and perfect the validity and first priority of any security
         interests created pursuant to the Security Documents. Borrower will
         also provide and cause its Subsidiaries to provide at their own expense
         to the Administrative Agent such title records or opinions as may be in
         the files of Borrower or its Subsidiaries and operating agreements and
         other instruments and documents relating to the Properties covered by
         the Security 




                                       11
<PAGE>   13

         Documents then in the possession of the Borrower or any Subsidiary as
         the Administrative Agent may reasonably request. At such time as no
         Event of Default is continuing and Borrower is satisfying the Debt
         Reduction Requirement, upon request by Borrower to Administrative
         Agent, Administrative Agent shall advise the Collateral Agent, pursuant
         to the terms of the Security Documents, to terminate all Security
         Documents and release all Liens created thereby."

         i.                Subsection 5.2(a)(5) of the Credit Agreement is 
                  hereby amended and restated to read in its entirety as
                  follows:

         "        (5)      Debt, other than Debt otherwise permitted by
                           another subparagraph of this Section 5.2(a), which,
                           at the time incurred, is (i) at prevailing market
                           rates of interest and contains covenants and
                           conditions and events of default no more onerous to
                           Designated Entities than the terms of this Agreement;
                           provided, that no Default or Event of Default either
                           (A) exists at the time of the issuance of such Debt
                           and (B) will result from, and be continuing after,
                           the incurrence of such Debt; provided further, that
                           in the case of a Debt Issuance, if Borrower is not
                           satisfying the Debt Reduction Requirement immediately
                           prior to the incurrence of Debt under such Debt
                           Issuance, such Debt shall have a final maturity after
                           August 7, 2002 and be on terms and conditions
                           reasonably acceptable to the Administrative Agent."

         j.                Section 5.2(e) of the Credit Agreement is amended and
                  restated to read in its entirety as follows:

         "        (e)      Limitation on Dividends and Other Restricted 
                           Payments. The Borrower will not and will not permit
                           any of its Subsidiaries to pay or declare dividends
                           (other than stock dividends) on, or repurchase, the
                           Borrower's capital stock in excess of $10,000,000 in
                           the aggregate for all such payments and purchases in
                           any Fiscal Year. Borrower will not, and will not
                           permit any Restricted Subsidiary to, make any other
                           Restricted Payments in excess of $5,000,000 in the
                           aggregate for all such Restricted Payments during any
                           Fiscal Year; provided, however, that in the event
                           that any Unrestricted Subsidiary of Borrower is
                           redesignated to be a Restricted Subsidiary of
                           Borrower for purposes of this Agreement, then for
                           purposes of redetermining compliance with this
                           Section, all Restricted Payments made to such
                           Unrestricted Subsidiary shall be deducted from the
                           aggregate total of all Restricted payments made
                           during such Fiscal Year. No Restricted Payment may be
                           made (1) if the Obligations shall exceed the Facility
                           Amount, (2) if any Default or Event of Default shall
                           have occurred and be continuing, or (3) if as a
                           result thereof, any Default or Event of Default shall
                           occur and be continuing."



                                       12
<PAGE>   14

         k.                Subsection 5.2 of the Credit Agreement is amended by
                  adding the following Section 5.2(m).

                  "(m)     "At any time that the Borrower is not satisfying the 
                           Debt Reduction Requirement, the Borrower will not,
                           and will not permit any of its Subsidiaries to, sell,
                           transfer, assign or otherwise convey any Property
                           (other than to the Borrower or one of its
                           Subsidiaries) to the extent the aggregate value of
                           non-cash consideration for all sales, transfers,
                           assignments and other conveyances of any Property
                           (other than to the Borrower or one of its
                           Subsidiaries) received on and after February 1, 1999
                           has exceeded or would exceed $25,000,000 in the
                           aggregate. As used herein, the term "non-cash
                           consideration" means any consideration given by or on
                           behalf of the purchaser of Property other than cash,
                           any cash equivalent or any other asset to the extent
                           that at the time in question such other asset has
                           been converted (by collection, sale or otherwise)
                           into cash or any cash equivalent. The value of any
                           such non-cash consideration shall be its fair market
                           value at the time that the contract for such sale,
                           transfer, assignment or other conveyance is entered
                           into, which fair market value shall be determined (i)
                           by reference to market quotations in the case of
                           publicly traded securities or other consideration of
                           the type which is subject to market quotations, (ii)
                           if clause (i) is not applicable, by the value for
                           such consideration set forth in such contract by the
                           parties or (iii) if neither (i) or (ii) is
                           applicable, by a resolution of the board of directors
                           of the Borrower.

         l.                Section 5.3(a) of the Credit Agreement is hereby 
                  amended and restated to read in its entirety as follows:

         "        (a)      Senior Leverage Ratio. Borrower's Consolidated Senior
         Leverage Ratio will not (i) as of the last day of the Fiscal Quarters
         ending March 31, 1999, June 30, 1999 and September 30, 1999, be greater
         than 5.75 to 1.0, (ii) as of the last day of the Fiscal Quarters ending
         December 31, 1999 and March 31, 2000, be greater than 4.25 to 1.0, and
         (iii) as of the last day of any Fiscal Quarter ending on or after June
         30, 2000, be greater than 3.50 to 1.00."

         m.                Section 5.3(b) of the Credit Agreement is hereby 
                  amended and restated to read in its entirety as follows:

         "        (b)      Total Leverage Ratio. Borrower's Consolidated Total 
         Leverage Ratio will not (i) as of the last day of all Fiscal Quarters
         ending prior to June 30, 2000, be greater than 5.75 to 1.00, and (ii)
         as of the last day of any Fiscal Quarter ending on or after June 30,
         2000, be greater than 4.25 to 1.00."

         n.                Section 5.3 of the Credit Agreement is hereby amended
                  by inserting after Section 5.3(b) of the Credit Agreement the
                  following Sections 5.3(c) and 5.3(d):





                                       13
<PAGE>   15

         "        (c)      Minimum Consolidated Tangible Net Worth. Borrower 
         will not permit its Consolidated Tangible Net Worth as of the end of
         any Fiscal Quarter, commencing with the Fiscal Quarter ending March 31,
         1999, to be less than (i) $600,000,000 plus (ii) an amount equal to 50%
         of the sum of Borrower's and its Subsidiaries' Consolidated net income
         for each Fiscal Quarter, beginning with the Fiscal Quarter ending March
         31, 1999, during which such Consolidated net income is greater than $0
         plus (iii) an amount equal to 85% of the net cash proceeds received by
         the Borrower and its Subsidiaries from the issuance of any common
         stock, preferred stock or other equity for each Fiscal Quarter,
         beginning with the Fiscal Quarter ending March 31, 1999.

                  (b)      Properties NPV to Total Debt Ratio. Borrower's 
         Properties NPV to Total Debt Ratio will not as of the end of any Fiscal
         Quarter ending either June 30th or December 31st, commencing with the
         Fiscal Quarter ending December 31, 1998, be less than 1.25 to 1.00."

         o.                The Credit Agreement is hereby amended by replacing 
                  Exhibit I to the Credit Agreement with Exhibit I to this
                  Amendment and Restatement.

         p.                The Credit Agreement is hereby amended by replacing 
                  Exhibit J to the Credit Agreement with Exhibit J to this
                  Amendment and Restatement.

         q.                The Credit Agreement is hereby amended by inserting 
                  Exhibit Q to this Amendment and Restatement as Exhibit Q to
                  the Credit Agreement following Exhibit P to the Credit
                  Agreement.

         r.                The Credit Agreement is hereby amended by replacing 
                  Schedule 3 to the Credit Agreement with Schedule 3 to this
                  Amendment and Restatement.

         s.                The Credit Agreement is hereby amended by replacing 
                  Schedule 4 to the Credit Agreement with Schedule 4 to this
                  Amendment and Restatement.

         t.                Schedule 5 to the Credit Agreement is hereby amended
                  by replacing Schedule 5 to the Credit Agreement with Schedule
                  5 to this Amendment and Restatement.

         SECTION 3. Additional Commitments. In the event that Canadian Imperial
Bank of Commerce, The Bank of Nova Scotia, Royal Bank of Canada, The Chase
Manhattan Bank of Canada, Morgan Guaranty Trust Company of New York,
NationsBank, N.A., The Toronto-Dominion Bank, First Union National Bank, and
Wachovia Bank, N.A., or their respective Affiliates shall each agree to increase
their Commitments hereunder by $37,954,477, $37,954,477, $37,954,477,
$33,210,167, $33,210,167, $33,210,167, $33,210,167, $14,232,929, and
$14,232,929, respectively, (such Lenders and their Affiliates herein the
"Increasing Lenders") by advising the Administrative Agent in writing that they
have so agreed to increase their Commitments hereunder and the Canadian Credit
Facility is terminated by the Effective Date of this Amendment and Restatement,
then (i) the Credit Agreement is further amended as provided in this Section 3,
(ii) the Increasing Lenders (but not the other Lenders) shall make a Revolving
Loan




                                       14
<PAGE>   16

Advance on the Effective Date (herein the "Effective Date Revolving Loan
Advance") equal to their respective pro rata share, which Effective Date
Revolving Loan Advance will be in an amount necessary to pay, and will be used
for the purpose of paying, the outstanding Obligations under the Canadian Credit
Facility, (iii) such Effective Date Revolving Loan Advances will be Revolving
Loan Advances for all purposes of the Credit Agreement, (iv) the Increasing
Lenders, the Borrower and the Administrative Agent will cooperate to select
Eurodollar Interest Periods for such Effective Date Revolving Loan Advances that
are similar to the Eurodollar Interest Periods for the Revolving Loan Advances
outstanding under the Credit Agreement on the Effective Date of this Amendment
and (v) the Borrower shall deliver to the Administrative Agent a Guaranty from
(A) Pioneer Natural Resources Canada, Inc., (B) Pioneer Natural Resources
(Argentina) S.A., and (C) Pioneer Natural Resources (Tierra del Fuego) S.A. If
such Increasing Lenders do not each so agree to increase their respective
Commitments hereunder by such date, then the provisions of this Section 3 only
of this Amendment and Restatement shall be of no force or effect.

A.       The definition of Facility Amount in Section 1.1 of the Credit 
Agreement is hereby amended and restated to read in its entirety as follows:

         "        "Facility Amount" means the aggregate amount of the 
         Commitments (which amount shall be $1,350,169,958 on March 19, 1999),
         as such amount may be reduced from time to time pursuant to the terms
         of this Agreement."

B.       The Credit Agreement is amended by replacing Schedule 1 to the Credit
Agreement with Schedule 1 to this Amendment and Restatement.

C.       In lieu of the definition of "Debt Reduction Requirement" added to the
Credit Agreement pursuant to Section 2.B above, the following definition shall
be added:

         "        "Debt Reduction Requirement" means that all of the following
         requirements shall have occurred (i) the expiration or termination in
         full of the commitments under, and the payment of all amounts under or
         in respect of, the 364 Day Facility, (ii) the reduction of the
         Commitments under this Agreement after February 1, 1999 by an aggregate
         amount of at least $410,000,000 and the payment of all Consolidated
         Total Funded Debt required to be paid as the result of such reduction
         and (iii) the maintenance of the Total Leverage Ratio at less than or
         equal to 4.25 to 1.00 for at least two consecutive Fiscal Quarters ,
         except that solely for purposes of Subsection 2.9(g) hereof,
         satisfaction of the Debt Reduction Requirement shall be determined
         using the following clause (iii) in lieu of the foregoing clause (iii):
         (iii) on the day on which the determination is made and after giving
         pro forma effect to any transaction occurring on such day (including
         repayment of Obligations to be made on such day) the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX for the four (4) Fiscal Quarters most recently ended prior to
         such day is less than or equal to 4.25 to 1, after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such most recently ended four Fiscal
         Quarters as if such assets or Property had been sold or acquired at the
         beginning of such four most recently ended Fiscal Quarters; provided
         that for purposes of the calculation in this clause (iii) for purposes
         solely of Section 2.9(g) hereof, (1) EBITDAX for the four Fiscal
         Quarters ending December 31, 1998 shall be




                                       15
<PAGE>   17

         deemed to be four times the EBITDAX for the Fiscal Quarter ending on
         such date after adjusting such EBITDAX on a pro forma basis for any
         assets or Property sold or acquired after the beginning of such Fiscal
         Quarter as if such assets or Property had been sold or acquired at the
         beginning of such Fiscal Quarter, (2) EBITDAX for the four Fiscal
         Quarters ending March 31, 1999 shall be deemed to be two times the
         EBITDAX for the semi-annual period ending on such date after adjusting
         such EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such semi-annual period ending on such
         date as if such assets or Property had been sold or acquired at the
         beginning of such semi-annual period ending on such date and (3)
         EBITDAX for the four Fiscal Quarters ending June 30, 1999 shall be
         deemed to be the product of 4/3rds times EBITDAX for the three Fiscal
         Quarters ending on such date after adjusting such EBITDAX on a pro
         forma basis for any assets or Property sold or acquired after the
         beginning of such three Fiscal Quarters as if such assets or Property
         had been sold or acquired at the beginning of such three Fiscal
         Quarters."

D.       In lieu of Subsection 2.9(h) added to the Credit Agreement pursuant to
Section 2.E above, the following Subsection 2.9(h) shall be added:

         "        (h)      Notwithstanding any other provision of this 
         Agreement, if during the period commencing March 19, 1999 and ending
         December 31, 1999 the aggregate reductions in Commitments pursuant to
         the foregoing subsection of this Section 2.9 is less than $410,000,000,
         on December 31, 1999 on such date the Commitments shall be
         automatically reduced by the remainder of (i) $410,000,000 minus (ii)
         the total of all reductions in the Commitment pursuant to the foregoing
         subsections of this Section 2.9 on or prior to December 31, 1999, and
         Borrower shall make a mandatory prepayment on December 31, 1999 in an
         amount sufficient to cause the sum of (i) all Lenders' Revolving Loan
         Advances (including any Revolving Loan Advances to be made but not yet
         made pursuant to a Request for Advance) outstanding at such time plus
         (ii) the LC Obligations of all Lenders at such time plus (iii) all
         Swing Line Advances to Borrower plus (iv) all Lenders' Competitive Bid
         Advances outstanding at such time not to exceed the Total Commitments
         after giving effect to such reduction."

E.       In lieu of the Subsection 5.1(n) added to the Credit Agreement pursuant
to Section 2H above, the following subsection shall be added:

         "        (n)      Springing Lien. In the event that (i) any Event of 
         Default has occurred and is continuing or (ii) at any time after August
         3, 1999 the sum of (A) aggregate Commitments under this Agreement plus
         (B) the aggregate "Commitments" under the 364 Day Credit Facility,
         exceeds $1,050,000,000, then, without affecting in any way any other
         rights of the Lenders hereunder, the Administrative Agent, at the
         direction of the Required Lenders, may request that the Borrower, and
         the Borrower agrees to:

                                    (i) duly execute and deliver to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent) the Security Documents and cause each
                  such Security Document to be filed, registered and 




                                       16
<PAGE>   18

                  recorded, as the law may require or the Administrative Agent
                  may request, in each jurisdiction where so required or
                  requested, and deliver to the Administrative Agent an
                  acknowledgment copy, or other evidence satisfactory to it, of
                  each such filing, registration and recordation, in order to
                  mortgage, assign, grant a security interest in and pledge to
                  the Administrative Agent (or such other Person designated by
                  the Administrative Agent), acting on behalf of the Lenders,
                  all of the Borrower's and the Restricted Subsidiaries' right,
                  title and interest in and to the Properties located in the
                  United States, and the proceeds thereof, having a Properties
                  NPV, as of the date of the most recent Engineering Report, of
                  80% of the aggregate Properties NPV attributable to Properties
                  located in the United States (the "Collateral") in such
                  request, and to perfect and evidence the first priority of all
                  such Security Documents (subject to liens and encumbrances
                  permitted by the terms of such instruments); provided that the
                  Borrower shall not, and shall not permit any of its
                  Subsidiaries to, on or after the Effective Date enter into any
                  amendment of any such contract or agreement, or enter into any
                  other contract or agreement, that in either case would result
                  in any additional such material consent, authorization or
                  approval requirement; and

                                    (ii) deliver to the Administrative Agent,
                  within 30 days of such request for delivery of the Security
                  Documents (or, if a Person other than the Administrative Agent
                  is to act as collateral agent under the Security Documents, if
                  later, within fifteen (15) days of the designation and
                  acceptance by such Person of the collateral agency), evidence
                  acceptable to the Administrative Agent, in its reasonable
                  discretion, indicating that Security Documents covering 80% of
                  the Properties NPV attributable to the Properties located in
                  the United States have been executed, acknowledged, filed,
                  registered and recorded, as the law may require or the Agent
                  may request, in each jurisdiction where so required or
                  requested.

         Borrower further agrees to execute, or cause its Subsidiaries to
         execute, any and all further documents, financing statements,
         agreements and instruments, and take all further actions (including
         filing Uniform Commercial Code financing statements), which may be
         required under applicable law, or which the Administrative Agent may
         reasonably request, in order to effectuate the transactions
         contemplated by this Section 5.1(n) and in order to grant, preserve,
         protect and perfect the validity and first priority of any security
         interests created pursuant to the Security Documents. Borrower will
         also provide and cause its Subsidiaries to provide at their own expense
         to the Administrative Agent such title records or opinions as may be in
         the files of Borrower or its Subsidiaries and operating agreements and
         other instruments and documents relating to the Properties covered by
         the Security Documents then in the possession of the Borrower or any
         Subsidiary as the Administrative Agent may reasonably request. At such
         time as no Event of Default is continuing and Borrower is satisfying
         the Debt Reduction Requirement, upon request by Borrower to
         Administrative Agent, Administrative Agent shall advise the Collateral
         Agent, pursuant to the terms of the Security Documents, to terminate
         all Security Documents and release all Liens created thereby."





                                       17
<PAGE>   19

F.       Subsection 2.9(j) added to the Credit Agreement pursuant to Section 2E
above is deleted from the Credit Agreement in its entirety.

         SECTION 4. Representations and Warranties. To confirm each Lender's
understanding concerning Borrower and its businesses, properties and
obligations, and to induce the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender to enter into this Amendment and Restatement, the
Borrower hereby reaffirms to the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender that, as of the date hereof, its representations and
warranties contained in Section 4.1 of the Credit Agreement (as amended by this
Amendment and Restatement) and in the other Loan Documents to which it is a
party (except to the extent such representations and warranties relate solely to
an earlier date) are true and correct and additionally represents and warrants
as follows:

A.       The execution and delivery of this Amendment and Restatement and the
         performance by the Borrower and the Restricted Subsidiaries of their
         respective obligations under this Amendment and Restatement, the Credit
         Agreement and the other Loan Documents, as amended hereby, are within
         the Borrower's or such Restricted Subsidiaries' corporate or
         partnership powers, have been duly authorized by all necessary
         corporate or partnership action, have received all necessary
         governmental approval (if any shall be required), and do not and will
         not contravene or conflict with any provision of law or of the
         Borrower's or such Restricted Subsidiaries' charter or bylaws or
         partnership agreement or of any contractual restriction, law or
         governmental regulation or court decree or order binding on or
         affecting the Borrower or such Restricted Subsidiary.

B.       This Amendment and Restatement and the Credit Agreement as amended
         hereby are, and the other Loan Documents when duly executed and
         delivered will be, legal, valid and binding obligations of the Borrower
         and each Restricted Subsidiary which is a party hereto or thereto,
         enforceable in accordance with their terms except as such enforcement
         may be limited by bankruptcy, insolvency or similar laws of general
         application relating to the enforcement of creditors' rights generally
         and by general principles of equity.

         SECTION 5. Conditions to Effectiveness. The effectiveness of this
Amendment and Restatement is conditioned upon receipt by the Administrative
Agent of all the following documents and items, each in form and substance
reasonably satisfactory to the Administrative Agent:

         A.       this Amendment and Restatement executed by the Borrower and
                  the Required Lenders.

         B.       Delivery of the Initial Engineering Report.

         C.       Payment to Administrative Agent for the account of each Lender
                  which executes and delivers a copy of this Amendment and
                  Restatement to the Administrative Agent on or before March 19,
                  1999, of a non-refundable amendment fee payable to each such
                  Lender determined by applying the Amendment Fee Rate to such
                  Lender's Percentage Share of the Facility Amount as of the
                  date of this Amendment and Restatement.

         D.       Payment to Administrative Agent for the account of NationsBanc
                  Montgomery Securities LLC, as sole arranger and book manager,
                  a non-refundable advisory fee in the amount set 



                                       18
<PAGE>   20

                  forth in that certain Commitment/Fee Letter, dated February 4,
                  1999 between NationsBanc Montgomery Securities LLC and the
                  Borrower.

         E.       Delivery of favorable opinions of counsel for Borrower and the
                  Restricted Subsidiaries, in form and substance acceptable to
                  the Administrative Agent, in its sole discretion.

         F.       Unless the Canadian Credit Facility shall have terminated, the
                  Required Lenders (as defined in the Canadian Credit Facility)
                  shall have consented to this Amendment, it being agreed by the
                  parties hereto that such consent may require reductions in
                  commitments and paydowns under the Canadian Credit Facility
                  similar to the reductions and paydowns required by Sections
                  2.9(d), (e) and (f) added by Section 2E above and to the
                  extent permitted by Section 2.9(j) added by Section 2E above.

         H.       Such other documents or items that the Administrative Agent
                  may reasonably request.

         SECTION 6. Reaffirmation of Credit Agreement. This Amendment and
Restatement constitutes a "Loan Document" as defined in the Credit Agreement and
shall be deemed to be an amendment and restatement of the Credit Agreement, and
the Credit Agreement, as amended and restated hereby, is hereby ratified,
approved and confirmed in each and every respect. All references to the Credit
Agreement or the Credit Facility Agreement in any other document, instrument,
agreement or writing shall hereafter be deemed to refer to this Amendment and
Restatement.

         SECTION 7. Parties in Interest. All grants, covenants and agreements
contained in this Amendment and Restatement shall bind and inure to the benefit
of the parties thereto and their respective successors and assigns; provided,
however, that no Restricted Subsidiary may assign or transfer any of its rights
or delegate any of its duties or obligations under this Amendment and
Restatement or any Loan Document without the prior written consent of all
Lenders.

         SECTION 8. Counterparts. This Amendment and Restatement may be
separately executed in any number of counterparts and by different parties
hereto in separate counterparts, each of which when so executed shall be deemed
to constitute one and the same Amendment and Restatement.

         SECTION 9. GOVERNING LAW. THIS AMENDMENT AND RESTATEMENT AND THE OTHER
LOAN DOCUMENTS SHALL BE DEEMED CONTRACTS AND INSTRUMENTS MADE UNDER THE LAWS OF
THE STATE OF TEXAS AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF THE STATE OF TEXAS AND THE LAWS OF THE UNITED STATES OF
AMERICA, WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW. CHAPTER 15 OF TEXAS
REVISED CIVIL STATUTES ANNOTATED ARTICLE 5069 (WHICH REGULATES CERTAIN REVOLVING
CREDIT LOAN ACCOUNTS AND REVOLVING TRI-PARTY ACCOUNTS) DOES NOT APPLY TO THIS
AMENDMENT AND RESTATEMENT OR TO THE NOTES.

         SECTION 10. Severability. If any term or provision of this Amendment
and Restatement or of any Loan Document shall be determined to be illegal or
unenforceable in any jurisdiction, such term or 




                                       19
<PAGE>   21

provision shall, as to such jurisdiction, be illegal or unenforceable, without
affecting the remaining terms or provisions in that jurisdiction or the legality
or enforceability of such terms or provisions in any other jurisdiction.

         SECTION 11. WAIVER OF JURY TRIAL, PUNITIVE DAMAGES. EACH OF THE
BORROWER, AGENTS AND LENDERS HEREBY (I) IRREVOCABLY WAIVES, TO THE MAXIMUM
EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY LITIGATION, DIRECTLY OR INDIRECTLY, AT ANY TIME ARISING OUT OF,
UNDER OR IN CONNECTION WITH THE LOAN DOCUMENTS OR ANY TRANSACTION CONTEMPLATED
THEREBY OR ASSOCIATED THEREWITH, BEFORE OR AFTER MATURITY; (II) IRREVOCABLY
WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO
CLAIM OR RECOVER IN ANY SUCH LITIGATION ANY EXEMPLARY, PUNITIVE OR CONSEQUENTIAL
DAMAGES; (III) CERTIFIES THAT NO PARTY HERETO NOR ANY REPRESENTATIVE OR AGENT OR
COUNSEL FOR ANY PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, OR IMPLIED
THAT SUCH PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE
FOREGOING WAIVERS; AND (IV) ACKNOWLEDGES THAT IT HAS BEEN INDUCED TO ENTER INTO
THIS AMENDMENT AND RESTATEMENT, THE OTHER LOAN DOCUMENTS AND THE TRANSACTIONS
CONTEMPLATED HEREBY AND THEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS CONTAINED IN THIS SECTION.

         SECTION 12. FORUM SELECTION AND CONSENT TO JURISDICTION. ANY LITIGATION
BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AMENDMENT
AND RESTATEMENT OR ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF
DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENTS, THE
LENDERS OR THE BORROWER SHALL BE BROUGHT AND MAINTAINED EXCLUSIVELY IN THE
COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE
NORTHERN DISTRICT OF TEXAS; PROVIDED, HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT
AGAINST ANY COLLATERAL OR OTHER PROPERTY MAY BE BROUGHT, AT THE COLLATERAL
AGENT'S OPTION, IN THE COURTS OF ANY JURISDICTION WHERE SUCH COLLATERAL OR OTHER
PROPERTY MAY BE FOUND. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE
JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND THE UNITED STATES DISTRICT
COURT FOR THE NORTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION
AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED
THEREBY IN CONNECTION WITH SUCH LITIGATION. BORROWER FURTHER IRREVOCABLY
CONSENTS TO THE SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE PREPAID, OR BY
PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF TEXAS. FOR THE PURPOSE OF ANY
ACTION OR PROCEEDING INSTITUTED IN THE FEDERAL OR STATE COURTS OF TEXAS, EACH
RESTRICTED SUBSIDIARY OF THE BORROWER HEREBY IRREVOCABLY DESIGNATES BORROWER
WITH OFFICES ON THE DATE HEREOF AT 1400 WILLIAMS 




                                       20
<PAGE>   22

SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD, IRVING, TEXAS 75039 TO RECEIVE FOR
AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY, SERVICE OF PROCESS IN TEXAS.
BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT
PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO THE
LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO
ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT
FORUM. TO THE EXTENT THAT THE BORROWER HAS OR HEREAFTER MAY ACQUIRE ANY IMMUNITY
FROM JURISDICTION OF ANY COURT OR FROM ANY LEGAL PROCESS (WHETHER THROUGH
SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT, ATTACHMENT IN AID OF EXECUTION
OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS PROPERTY, BORROWER HEREBY
IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS OBLIGATIONS UNDER THIS
AMENDMENT AND RESTATEMENT AND THE OTHER LOAN DOCUMENTS.

         SECTION 13. Effectiveness. This Amendment and Restatement shall become
effective as of March 19, 1999 ("Effective Date"), when counterparts hereof
executed on behalf of the Borrower and the Required Lenders (or notice thereof
satisfactory to the Agent) shall have been received by the Administrative Agent,
and all conditions set forth in Section 4 hereof have been fulfilled.

         SECTION 14. Entire Agreement. THIS WRITTEN AMENDMENT AND RESTATEMENT
AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT
ORAL AGREEMENTS OF THE PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                    [SIGNATURES BEGIN ON THE FOLLOWING PAGE]




                                       21
<PAGE>   23


         IN WITNESS WHEREOF, this Amendment and Restatement is executed as of
the date first written above.

                                   BORROWER:

                                   PIONEER NATURAL RESOURCES
                                   COMPANY

                                   By:
                                      -----------------------------------------
                                   Name:    M. Garrett Smith
                                   Title:   Executive Vice President and Chief
                                            Financial Officer





                                      S-1
<PAGE>   24





                                  LENDERS:

                                  NATIONSBANK, N.A., successor-by-merger
                                  to NationsBank of Texas, N.A., individually
                                  and as Administrative Agent and as Collateral
                                  Agent

                                  By:
                                     -------------------------------------------
                                  Name:
                                  Title:






                                      S-2
<PAGE>   25






                               CIBC INC., individually and as
                               Documentation Agent

                               
                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-3
<PAGE>   26






                               MORGAN GUARANTY TRUST
                               COMPANY OF NEW YORK, individually
                               and as Documentation Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:











                                      S-4
<PAGE>   27

                               CHASE BANK OF TEXAS, NATIONAL
                               ASSOCIATION, as successor-in-interest to
                               The Chase Manhattan Bank, individually and as
                               Syndication Agent

                               By:
                                  -------------------------------------------
                               Name:
                               Title:









                                      S-5
<PAGE>   28





                   [SIGNATURE PAGE S-6 INTENTIONALLY OMITTED]














                                      S-6
<PAGE>   29






                               THE BANK OF NEW YORK, individually
                               and as Co-Agent

                               By:
                                  -------------------------------------------
                               Name:
                               Title:




                                      S-7
<PAGE>   30






                               THE BANK OF NOVA SCOTIA,
                               individually and as Co-Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:





                                      S-8
<PAGE>   31





                               ROYAL BANK OF CANADA, individually
                               and as Co-Agent



                               By:
                                  -------------------------------------------
                               Name:
                               Title:











                                      S-9
<PAGE>   32



                               UNION BANK OF CALIFORNIA, N.A.,
                               individually and as Co-Agent



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-10
<PAGE>   33





                               WELLS FARGO BANK, N.A.,
                               individually and as Co-Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-11
<PAGE>   34





                               BANK ONE, TEXAS, N.A., individually



                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-12
<PAGE>   35






                               DEN NORSKE BANK ASA, individually and
                               as Lead Manager


                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-13
<PAGE>   36





                               PARIBAS, individually and as Lead Manager




                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-14
<PAGE>   37





                               FIRST UNION NATIONAL BANK,
                               individually and as Lead Manager




                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-15
<PAGE>   38





                               BANKERS TRUST COMPANY, as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-16
<PAGE>   39





                               CREDIT AGRICOLE INDOSUEZ, as a
                               Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-17
<PAGE>   40






                               NATEXIS BANQUE, as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:








                                      S-18
<PAGE>   41





                               TORONTO DOMINION (TEXAS), INC., as
                               a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:





                                      S-19
<PAGE>   42





                               THE TOYO TRUST & BANKING CO.,
                               LTD., as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-20
<PAGE>   43





                               WACHOVIA BANK, N.A., as a Lender


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-21
<PAGE>   44





                               THE DAI-ICHI KANGYO BANK, LTD.,
                               NEW YORK BRANCH, as a Lender





                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-22
<PAGE>   45





                               THE SANWA BANK, LIMITED, as a
                               Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:









                                      S-23
<PAGE>   46





                               KBC BANK N.V., as a Lender




                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:



                                      S-24


<PAGE>   47





                                    Exhibit I

               Organization Chart of Borrower and its Subsidiaries









                               Exhibit I - Page 1

<PAGE>   48




                                    Exhibit J

                    Form of Designated Officer's Certificate

         Reference is made to (i) the Primary Credit Facility pursuant to that
certain Second Amended and Restated Credit Facility Agreement dated as of March
19, 1999, by and among Borrower, NationsBank, N.A., as Administrative Agent,
CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New York, as
Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the
Co-Agents party thereto, and the Lenders from time to time parties thereto (the
"Primary Credit Agreement") and (ii) the 364 Day Credit Facility pursuant to
that certain Second Amended and Restated Credit Facility Agreement dated as of
March 19, 1999, by and among Borrower, NationsBank, N.A., as Administrative
Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New
York, as Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the Co-
Agents party thereto, and the Lenders from time to time parties thereto (the
"364 Day Credit Agreement" and, together with the Primary Credit Facility, the
"Credit Agreements"). Terms which are defined in the Credit Agreements and which
are used but not defined herein are used herein with the meanings given them in
the Credit Agreements.

         This Certificate is furnished pursuant to Section 5.1(b)(2) of the
Credit Agreements. Together herewith the Borrower is furnishing to Managing
Agents, the Co-Agents and each Lender the Borrower's [FINANCIAL STATEMENTS] (the
"Financial Statements") as of (the "Reporting Date"). The Borrower hereby
represents, warrants, and acknowledges to Agents and each Lender that:

         (a)      the Designated Officer of the Borrower signing this instrument
                  is a duly elected, qualified and acting officer of the
                  Borrower;

         (b)      the Financial Statements are accurate and complete and satisfy
                  the requirements of the Credit Agreements;

         (c)      attached as Schedule I hereto is a schedule of calculations
                  showing compliance (or noncompliance, as the case may be) as
                  of the Reporting Date with the requirements of Sections 5.2(e)
                  and 5.3 of the Credit Agreements; and

         (d)      on the Reporting Date, the Borrower was, and on the date
                  hereof the Borrower is, in full compliance with the disclosure
                  requirements of Section 5.1(d) of the Credit Agreements, and
                  no Default otherwise existed on the Reporting Date or
                  otherwise exists on the date of this Certificate [except for
                  Default(s) under Section(s)________ of the Credit Agreements,
                  which [is/are] more fully described on a schedule attached 
                  hereto].






                                Exhibit J - Page 1
<PAGE>   49





         The Designated Officer of the Borrower signing this instrument hereby
certifies that he has reviewed the Loan Documents and the Financial Statements
and has otherwise undertaken such inquiry as is in his opinion necessary to
enable him to express an informed opinion with respect to the above
representations, warranties and acknowledgments of the Borrower and, to the best
of his knowledge, such representations, warranties, and acknowledgments are
true, correct and complete.

                               PIONEER NATURAL RESOURCES
                               COMPANY


                               By:
                                  -------------------------------------------
                               Name:
                               Title:

                               Date:
                                    -----------------------------------------







                               Exhibit J - Page 2
<PAGE>   50






                                   Schedule I

================================================================================

COMPLIANCE WITH COVENANTS AS OF              . ($ in 000's)
                                -------------
================================================================================

A.     SENIOR LEVERAGE RATIO                                           =========

                      Minimum ratio allowed         : 1      
                                                 ========= 
B.     TOTAL LEVERAGE RATIO                                            =========

                      Minimum ratio allowed         : 1      
                                                 ========= 
C.     CONSOLIDATED TANGIBLE NET WORTH                                 =========

                      Minimum allowed                                      

[D.    PROPERTIES NPV TO TOTAL DEBT RATIO                              =========

                      Minimum ratio allowed         : 1    ](1)
                                                 =========
E.     RESTRICTED PAYMENTS DURING PRECEDING FISCAL QUARTER             =========

================================================================================

COMPUTATION OF FINANCIAL REQUIREMENTS AND RATIOS AS OF              
                                                       ----------
================================================================================

A.       SENIOR LEVERAGE RATIO (Section 5.3(a)) ($ in 000's)

               (i)    SENIOR DEBT:

                      (a)       Consolidated Total Debt:  $ 
                                                           ----------
                      (b)       Less Subordinated Debt:         $  
                                                                 ----------   
                      SENIOR DEBT:                                    $
                                                                       ---------

- -------------------
  (1)  Properties NPV to Total Debt Ratio only calculated for Fiscal Quarters
       ending June 30th and December 31st of each Fiscal Year



                               Exhibit J - Page 3
<PAGE>   51



            (ii)  EBITDAX                                               $
                                                                        ========
       SENIOR LEVERAGE RATIO ((i)(ii))        
                                                                        ========
                  Minimum ratio allowed          :1     
                                             =========

B.     TOTAL LEVERAGE RATIO (Section 5.3(B)) ($ in 000's)

            (i)   CONSOLIDATED TOTAL DEBT :                             $
                                                                        --------
            (ii)  EBITDAX                                               $
                                                                        ========
       TOTAL LEVERAGE RATIO ((i)(ii))                        
                                                                        ========
                  Minimum ratio allowed          :1     
                                             =========

C.     CONSOLIDATED TANGIBLE NET WORTH (Section 5.3(c)) ($ in 000's)

       CONSOLIDATED TANGIBLE NET WORTH

            (i)   Consolidated shareholder's equity of 
                  Borrower and its Subsidiaries                         $
                                                                        --------
            (ii)  Less Consolidated intangible assets of 
                  Borrower and its Subsidiaries                         $
                                                                        --------
            (iii) Plus aggregate amount of any non-cash write downs,
                  on a consolidated basis, by Borrower and its 
                  Subsidiaries                                          $
                                                                        
                                                                        --------
            (iv)  Plus 50% of the sum of Borrower's and its Subsidiaries
                  Consolidated net income for each Fiscal Quarter beginning
                  with the fiscal quarter ending March 31, 1999         $
                                                                        --------

            (iv)  Plus 85% of the net cash proceeds received by the Borrower
                  and its Subsidiaries from the issuance of any common
                  stock, preferred stock or other equity for each Fiscal
                  Quarter beginning  with the Fiscal Quarter ending 
                  March 31, 1999.                                       $
                                                                        --------

                  CONSOLIDATED TANGIBLE NET WORTH                       $
                                                                        ========
                  Minimum allowed                                               
                                                  ========
[D.    PROPERTIES NPV TO TOTAL DEBT RATIO                               ========

                  (i)      PROPERTIES NPV                               $
                                                                        --------




                               Exhibit J - Page 4
<PAGE>   52



                  (ii)     TOTAL DEBT                                   $
                                                                         =======

         PROPERTIES TO TOTAL DEBT RATIO ((i)(ii))     
                                                                         =======
                           Minimum ratio allowed      :1     ](2)
                                                   ========= 








- -------------------------
        (2)       Properties NPV to Total Debt Ratio only calculated for Fiscal
                  Quarters ending June 30th and December 31st of each Fiscal
                  Year






                               Exhibit J - Page 5
<PAGE>   53





                                    Exhibit Q

                                    [Form of]

                  MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                        AGREEMENT AND FINANCING STATEMENT

                                      FROM

                       ---------------------------------
                          (Taxpayer I.D. No._________)

                                       TO

                         ____________________, Trustee

                                       AND

                         ____________________, Trustee

                                       AND

                        ______________________________,
                               as Collateral Agent
                           (Taxpayer I.D. No.________)


                       Dated as of ________________, 1999

- --------------------------------------------------------------------------------

"THIS INSTRUMENT CONTAINS AFTER-ACQUIRED PROPERTY PROVISIONS."

"THIS INSTRUMENT SECURES PAYMENT OF FUTURE ADVANCES."

"THE OIL AND GAS INTERESTS INCLUDED IN THE MORTGAGED PROPERTY WILL BE FINANCED
AT THE WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES DESCRIBED IN EXHIBIT A
HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER
PLACES, IN THE REAL ESTATE RECORDS."

"THOSE PORTIONS OF THE MORTGAGED PROPERTY WHICH ARE MINERALS OR OTHER SUBSTANCES
OF VALUE WHICH MAY BE EXTRACTED FROM THE EARTH (INCLUDING, WITHOUT LIMITATION,
OIL AND GAS), AND THE ACCOUNTS RELATING THERETO, WILL BE FINANCED AT THE
WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES 



                               Exhibit Q - Page 1
<PAGE>   54


DESCRIBED IN EXHIBIT A HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR
RECORD, AMONG OTHER PLACES, IN THE REAL ESTATE RECORDS."

"THE MORTGAGOR HAS AN INTEREST OF RECORD IN THE REAL ESTATE CONCERNED,
WHICH IS DESCRIBED IN EXHIBIT A HERETO."

"THIS INSTRUMENT IS A LINE OF CREDIT MORTGAGE."

"SOME OF THE PERSONAL PROPERTY CONSTITUTING A PORTION OF THE MORTGAGED PROPERTY
IS OR IS TO BE AFFIXED TO THE PROPERTIES DESCRIBED IN EXHIBIT A HERETO, AND THIS
FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER PLACES, IN THE REAL
ESTATE RECORDS."

"A POWER OF SALE HAS BEEN GRANTED IN THIS MORTGAGE.  A POWER OF SALE MAY
ALLOW THE MORTGAGEE TO TAKE THE MORTGAGED PROPERTY AND SELL IT WITHOUT
GOING TO COURT IN A FORECLOSURE ACTION UPON DEFAULT BY THE MORTGAGOR
UNDER THIS MORTGAGE."

"THE AMOUNT INVOLVED IS $200 OR MORE."

THIS INSTRUMENT WAS PREPARED BY AND
WHEN RECORDED AND/OR FILED
RETURN TO:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, TX  77002






                               Exhibit Q - Page 2
<PAGE>   55





                  MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                        AGREEMENT AND FINANCING STATEMENT

         THIS MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY AGREEMENT AND
FINANCING STATEMENT, dated as of , 1999, is from
_______________________________, a _________________ (herein called the
"Mortgagor"), to_________________________________ ____________________________
and __________________________, of _____________, _________________, as Trustees
(herein collectively called the "Trustees"), and ___________________, a
______________, having is principal place of business at ________________,
_____________ _____ as collateral agent (herein, in such capacity, together with
any successor(s) thereto in such capacity, called the "Collateral Agent") for
the Lenders and the Noteholders.

         1. For all purposes of this instrument, unless the context otherwise
requires:

                  A. "Borrower" shall mean the "Borrower" as defined in the
Primary Credit Agreement (hereinafter defined) [and the 364-Day Credit Agreement
(hereinafter defined)].

                  B. "Credit Agreement Notes" shall mean the "Notes" as defined
in the Primary Credit Agreement [and the "Notes" as defined in the 364-Day
Credit Agreement].

                  C. "Encumbrance" shall mean any irregularity in title, lien,
security interest, pledge, charge, encumbrance, claim, burden or defect.

                  D. "Hydrocarbons" shall mean oil, gas and other liquid or
gaseous hydrocarbons.

                  E. "Indenture Notes" shall mean each of the following: (i)
Borrower's $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's
$150,000,000 8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes due 2028,
and (v) and other publicly tradeable notes, bonds or debentures outstanding as
of February 1, 1999, which notes, bonds or debentures by their terms require
that they be secured equally and ratably with this instrument.

                  F. "Indenture Trustees" means each of the trustees from time
to time appointed pursuant to the terms of any indenture or similar agreement
governing any of the Indenture Notes.

                  G. "lands described in Exhibit A" shall include any lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference to another instrument or document, and
shall also include any lands now or hereafter unitized or pooled with lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference.

                  H. "Lenders" shall mean the "Lenders" as defined in the
Primary Credit Agreement [and the "Lenders" as defined in the 364-Day Credit
Agreement].

                  I. "Mortgaged Property" shall mean the properties, rights and
interests hereinafter described and defined as the Mortgaged Property.





                               Exhibit Q - Page 3
<PAGE>   56
                  



                  J. "Noteholders" means any owner or holder of any of the
Indenture Notes from time to time.

                  K. "oil and gas leases" shall include oil, gas and mineral
leases, subleases and assignments thereof, operating rights, and shall also
include subleases and assignments of operating rights.

                  L. "Operating Equipment" shall mean all surface or subsurface
machinery, goods, equipment, fixtures, inventory, facilities, supplies or other
property of whatsoever kind or nature (excluding drilling rigs, trucks,
automotive equipment or other property taken to the premises to drill a well or
for other similar temporary uses) now or hereafter located on or under any of
the lands described in Exhibit A which are useful for the production, gathering,
treatment, processing, storage or transportation of Hydrocarbons (together with
all accessions, additions and attachments to any thereof), including, but not by
way of limitation, all oil wells, gas wells, water wells, injection wells,
casing, tubing, tubular goods, rods, pumping units and engines, christmas trees,
platforms, derricks, separators, compressors, gun barrels, flow lines, tanks,
gas systems (for gathering, treating and compression), pipelines (including
gathering lines, laterals and trunklines), chemicals, solutions, water systems
(for treating, disposal and injection), power plants, poles, lines,
transformers, starters and controllers, machine shops, tools, storage yards and
equipment stored therein, buildings and camps, telegraph, telephone and other
communication systems, roads, loading docks, loading racks and shipping
facilities.

                  M. "Permitted Encumbrances" shall mean any or all of the
following:

                           (i) Lessors' royalties, overriding royalties,
         production payments, net profits interests and similar burdens on
         production from the Mortgaged Property;

                           (ii) Encumbrances that arise under operating
         agreements to secure payment of amounts which are not delinquent and
         are of a type and nature customary in the oil and gas industry;

                           (iii) Encumbrances that arise as a result of pooling
         and unitization agreements, declarations, orders or laws to secure
         payment of amounts which are not delinquent;

                           (iv) Encumbrances securing payments to mechanics and
         materialmen and Encumbrances securing payment of taxes, assessments or
         other governmental charges or levies that, in either case, are not
         delinquent or, if delinquent, are being contested in good faith in the
         normal course of business;

                           (v) consents to assignment by governmental
         authorities (a) that are obtained on or prior to the date hereof or (b)
         that are customarily obtained after the consummation of the
         transactions of the nature contemplated by this instrument;

                           (vi) farmouts, after payment interest and
         conventional rights of reassignment, of a type and nature customary in
         the oil and gas industry, obligating the Mortgagor to assign or
         reassign its interest in any portion of the Mortgaged Property to a
         third party, including





                               Exhibit Q - Page 4
<PAGE>   57

         in the event it intends to release or abandon such interest prior to
         the expiration of the primary term or other termination of such
         interest;

                           (vii) easements, rights-of-way, servitudes, permits,
         surface leases, surface use restrictions and other surface uses and
         impediments on, over or in respect of any of the Mortgaged Property
         that are not such as to interfere materially with the operation, value
         or use of any of the Mortgaged Property;

                           (viii) calls on or preferential rights to purchase
         production, of a type and nature and at a pricing structure customary
         in the oil and gas industry, held by parties other than the Mortgagor
         and its Subsidiaries;

                           (ix) covenants, conditions and other terms of the oil
         and gas leases and contracts, such covenants, conditions and terms of a
         type and nature customary in the oil and gas business, included in the
         Mortgaged Property;

                           (x) such Encumbrances as the Trustees have expressly
         waived in writing;

                           (xi) rights reserved to or vested in any municipality
         or governmental, tribal, statutory or public authority to control or
         regulate any of the Mortgaged Property in any manner, and all
         applicable laws, rules and orders of any municipality or governmental
         or tribal authority;

                           (xii) such Encumbrances which are validly existing
         and binding upon the Mortgagor's interest in the particular Mortgaged
         Properties as of the date of this Mortgage;

                           (xiii) Encumbrances permitted pursuant to Section
         5.2(b) of [either of] the Credit Agreement[s];

                           (xiv) judgment liens (A) in existence less than 15
         days after the entry thereof or (B) which execution has been stayed or
         the payment of which is covered in full (subject to a customary
         deductible) by insurance;

                           (xv) contractual obligations terminable upon no more
         than 90 days' prior notice to the counterparty thereunder providing for
         the sale of Hydrocarbons produced from the Mortgaged Properties;

                           (xvi) Encumbrances created under this instrument; and

                           (xvii) all other Encumbrances affecting any portion
         of the Mortgaged Property that individually or in the aggregate are not
         such as to interfere materially with the operation, value or use of any
         of the Mortgaged Property.

                  N. "Production Sale Contracts" shall mean contracts now in
effect, or hereafter entered into by the Mortgagor, or entered into by the
Mortgagor's predecessors in interest, for the sale,





                               Exhibit Q - Page 5
<PAGE>   58

purchase, exchange, gathering, transportation, treating or processing of
Hydrocarbons produced from the lands described in Exhibit A attached hereto and
made a part hereof.

                  O. "Secured Indebtedness" shall have the meaning set forth in
Section 1.2 hereof.

         NOW, THEREFORE, the Mortgagor, for and in consideration of the premises
and of the debts and trusts hereinafter mentioned, has granted, bargained, sold,
warranted, mortgaged, assigned, transferred and conveyed, and by these presents
does grant, bargain, sell, warrant, mortgage, assign, transfer and convey unto
the Trustees, in trust, with power of sale, for use and benefit of the
Collateral Agent for the equal and ratable benefit of the holders of the Secured
Indebtedness, all the Mortgagor's right, title and interest, whether now owned
or hereafter acquired, in and to all of the hereinafter described properties,
rights and interests; and, insofar as such properties, rights and interests
consist of equipment, general intangibles, accounts, contract rights, inventory,
fixtures, proceeds of collateral or any other personal property of a kind or
character defined in or subject to the applicable provisions of the Uniform
Commercial Code (as in effect in the appropriate jurisdiction with respect to
each of said properties, rights and interests), the Mortgagor hereby grants to
said Trustees, for the use and benefit of the Collateral Agent for the equal and
ratable benefit of the holders of the Secured Indebtedness, a security interest
therein; namely:

                  (a) the lands described in Exhibit A, and the oil and gas
         leases, the fee, mineral, overriding royalty, royalty and other
         interests which are specifically described in Exhibit A,

                  (b) the presently existing and (subject to the terms of
         Section 2.6 hereof) hereafter arising unitization, unit operating,
         communitization and pooling agreements and the properties covered and
         the units created thereby (including, without limitation, all units
         formed under orders, regulations, rules, approvals, decisions or other
         official acts of any federal, state or other governmental agency having
         jurisdiction) which are specifically described in Exhibit A or which
         relate to any of the properties and interests specifically described in
         Exhibit A,

                  (c) the Hydrocarbons which are in, under, upon, produced or to
         be produced from the lands described in Exhibit A,

                  (d) the Production Sale Contracts, and

                  (e) the Operating Equipment,

together with any and all corrections or amendments to, or renewals, extensions
or ratifications of, or replacements or substitutions for, any of the same, or
any instrument relating thereto, and all accounts, contracts, contract rights,
options, nominee agreements, operating agreements, processing agreements, farmin
agreements, farmout agreements, joint venture agreements, exploration
agreements, bottomhole agreements, dryhole agreements, support agreements,
acreage contribution agreements, insurance policies, title opinions, title
abstracts, title materials and information, files, records, writings, data
bases, information, systems, logs, well cores, fluid samples, production data
and reports, well testing data and reports, maps, seismic and geophysical,
geological and chemical data and information, interpretative and analytical
reports of any kind or nature, including, without limitation, reserve studies
and reserve evaluations, (to the extent 




                               Exhibit Q - Page 6
<PAGE>   59

the assignment or release of such agreements, opinions, data, information
systems, logs, cores, samples, and reports is not restricted by any contract or
agreement which is of a type and nature customary in the oil and gas industry)
rights-of-way, franchises, easements, servitudes, surface leases, permits,
licenses, tenements, hereditaments, appurtenances, general intangibles, rents,
issues, profits, products and proceeds, whether now or hereafter existing or
arising, used or useful in connection with, covering, relating to, or arising
from or in connection with, any of the aforesaid in this granting clause
referenced, and all other things of value and incident thereto (including,
without limitation, any and all liens, lien rights, security interests and other
rights and interests) which the Mortgagor might at any time have or be entitled
to, all the aforesaid properties, rights and interests, together with any
additions thereto which may be subjected to the lien and security interest of
this instrument by means of supplements hereto, being hereinafter called the
"Mortgaged Property."

         Subject, however, to (i) the restrictions, exceptions, reservations,
conditions, limitations, interests and other matters, if any, set forth or
referred to in the specific descriptions of such properties and interests in
Exhibit A (including all presently existing royalties, overriding royalties,
payments out of production and other burdens which are referred to in Exhibit A
and which are taken into consideration in computing any percentage, decimal or
fractional interest as set forth in Exhibit A), any Permitted Encumbrances, (ii)
the assignment of production contained in Article III hereof, but only insofar
and so long as said assignment of production is not inoperative under the
provisions of Section 3.1 hereof, and (iii) the condition that none of the
Trustees, the Collateral Agent, the Agents, the Lenders, the Noteholders or any
part thereof shall be liable in any respect for the performance of any covenant
or obligation of the Mortgagor in respect of the Mortgaged Property.

         TO HAVE AND TO HOLD the Mortgaged Property unto the Trustees forever to
secure the payment of the Secured Indebtedness and to secure the performance of
the obligations of the Mortgagor herein contained.

         The Mortgagor, in consideration of the premises, hereby covenants and
agrees with the Trustees and the Collateral Agent as follows:

                                    ARTICLE I
                              Indebtedness Secured

         1.1 Items of Indebtedness Secured. The following items of indebtedness
are secured hereby:

                  (a) that certain Second Amended and Restated Credit Facility
         Agreement - [Primary Facility], dated as of March 19, 1999, by and
         among Pioneer Natural Resources Company (the "Borrower"), NationsBank,
         N.A., as Administrative Agent (the "Administrative Agent"), CIBC Inc.,
         as Documentation Agent, Morgan Guaranty Trust Company of New York, as
         Documentation Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "Primary Credit Agreement"), which
         includes, without limitation, the Notes (as defined in the Primary
         Credit 




                               Exhibit Q - Page 7
<PAGE>   60

         Agreement), Obligations (as defined in the Primary Credit Agreement)
         and liabilities of the Borrower under and in connection with the
         Primary Credit Agreement;

                  (b) [that certain Second Amended and Restated Credit Facility
         Agreement - [364-Day Facility], dated as of March 19, 1999, by and
         among Borrower, the Administrative Agent, CIBC Inc., as Documentation
         Agent, Morgan Guaranty Trust Company of New York, as Documentation
         Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "364-Day Credit Agreement", and
         together with the Primary Credit Agreement, the "Credit Agreements"),
         which includes, without limitation, the Notes (as defined in the
         364-Day Credit Agreement), Obligations (as defined in the 364-Day
         Credit Agreement) and liabilities of the Borrower under and in
         connection with the 364-Day Credit Agreement;

                  (c)] The Indenture Notes;

                  (d) Any promissory note taken in extension or renewal of or in
         replacement or substitution for any of the Credit Agreement Notes or
         the Indenture Notes; and

                  (e) Any sums advanced or expenses or costs incurred by the
         Trustees or the Collateral Agent which are made or incurred pursuant
         to, or permitted by, the terms hereof, plus interest thereon at the
         rate herein specified or otherwise agreed upon, from the date of the
         advances or the incurring of such expenses or costs until reimbursed.

         1.2 Secured Indebtedness Defined. All the above items of indebtedness
are hereinafter collectively referred to as the "Secured Indebtedness."

                                   ARTICLE II
                       Particular Covenants and Warranties
                                of the Mortgagor

         2.1 Payment of the Secured Indebtedness. The Mortgagor will duly and
punctually pay the Secured Indebtedness, including each and every obligation
owing on account of the Credit Agreement Notes and the Indenture Notes.

         2.2 Warranties. The Mortgagor warrants and represents to the Trustees
and the Collateral Agent that (a) the oil and gas leases described in Exhibit A
hereto are valid, subsisting leases, superior and paramount to all other oil and
gas leases respecting the properties to which they pertain, (b) all producing
wells located on the lands described in Exhibit A have been drilled, operated
and produced in substantial compliance with all applicable laws, rules and
regulations of all authorities having jurisdiction and such wells are in fact
bottomed under and are producing from the lands described in Exhibit A or from
units in which such lands are unitized or pooled, (c) the Mortgagor has valid
and indefeasible title to each property right or interest constituting the
Mortgaged Property and has a good and legal right to grant and convey the same
to the Trustees, and (d) the Mortgaged Property is free from all encumbrances or
liens whatsoever, except for Permitted Encumbrances or as permitted by the
provisions of Section 2.5(f) hereof.




                               Exhibit Q - Page 8
<PAGE>   61

The Mortgagor will warrant and forever defend the Mortgaged Property unto the
Trustees against every person whomsoever lawfully claiming the same or any part
thereof, and the Mortgagor will maintain and preserve the lien and security
interest hereby created so long as any of the Secured Indebtedness remains
unpaid.

         2.3 Further Assurances. The Mortgagor will execute and deliver such
other and further instruments and will do such other and further acts as in the
opinion of the Trustees or the Collateral Agent may be necessary or desirable to
carry out more effectually the purposes of this instrument, including, without
limiting the generality of the foregoing, (a) proceeding with reasonable
diligence to promptly correct any Encumbrance which may hereafter be discovered
in the title to the Mortgaged Property other than Permitted Encumbrances, (b)
prompt correction of any defect in the execution and acknowledgment of this
instrument, and (c) prompt execution and delivery of all notices to parties
producing, purchasing or receiving proceeds of production from the Mortgaged
Property, and all division orders or transfer orders, any of which, in the
opinion of the Trustees or the Collateral Agent, is needed to transfer
effectually or to assist in transferring effectually to the Collateral Agent the
assigned proceeds of production from the Mortgaged Property.

         2.4 Taxes. Subject to the Mortgagor's right to contest the same, the
Mortgagor will promptly pay all taxes, assessments and governmental charges
legally imposed upon this instrument or upon the Mortgaged Property, or upon the
interest of the Trustees or the Collateral Agent, or upon the income and profits
thereof.

         2.5 Recording, etc. The Mortgagor will promptly, and at the Mortgagor's
expense, record, register, deposit and file this and every other instrument in
addition or supplemental hereto in such offices and places and at such times and
as often as may be necessary to preserve, protect and renew the lien and
security interest hereof as a first lien on and prior perfected security
interest in real or personal property, as the case may be, subject to the
Permitted Encumbrances, and the rights and remedies of the Trustees and of the
Collateral Agent, and otherwise will do and observe all things or matters
necessary or expedient to be done or observed by reason of any law or regulation
of any State or of the United States of America or of any other competent
authority, for the purpose of effectively creating, maintaining and preserving
the lien and security interest hereof on and in the Mortgaged Property, subject
to the Permitted Encumbrances.

         2.6 Pooling and Unitization of Mortgaged Property. Mortgagor shall have
the right, and is hereby authorized, without notice or consent to pool or
unitize all or any part of any tract of land described in Exhibit A, insofar as
related to the Mortgaged Property, with adjacent lands, leaseholds and other
interests, or enter into joint exploration or development agreements, when, in
the reasonable judgment of the Mortgagor, it is necessary or advisable to do so
in order to form a drilling unit to facilitate the orderly development of that
part of the Mortgaged Property affected thereby, or to comply with the
requirements of any law or governmental order or regulation relating to the
spacing of wells or proration of the production therefrom. Any unit so formed
may relate to one or more zones or horizons, and a unit formed for a particular
zone or horizon need not conform in area to any other unit relating to a
different zone or horizon, and a unit formed for the production of oil need not
conform in area with any unit formed for the production of gas. Upon written
request of the Trustees or the Collateral Agent, Mortgagor shall make available
to the Trustee and the Collateral Agent copies of all such existing pooling
agreements, declarations of pooling or other instruments creating such units.
The interest in any such unit attributable 



                               Exhibit Q - Page 9
<PAGE>   62

to the Mortgaged Property (or any part thereof) included therein shall become a
part of the Mortgaged Property and shall be subject to the lien hereof in the
same manner and with the same effect as though such unit and the interest of the
Mortgagor therein were specifically described in Exhibit A.

         2.7 Right of Entry. The Mortgagor will permit the Trustees and the
Collateral Agent, or the agents of any of them, to enter upon the Mortgaged
Property, and all parts thereof, for the purpose of investigating and inspecting
the condition and operation thereof.

                                   ARTICLE III
                            Assignment of Production

         3.1 Assignment. As further security for the payment of the Secured
Indebtedness, the Mortgagor hereby transfers, assigns, warrants and conveys to
the Collateral Agent for the equal and ratable benefit of the holders of Secured
Indebtedness, effective as of the date hereof, at 7:00 A.M., local time, all
Hydrocarbons which are thereafter produced from and which accrue to the
Mortgaged Property, and all proceeds therefrom. All parties producing,
purchasing or receiving any such Hydrocarbons, or having such, or proceeds
therefrom, in their possession for which they or others are accountable to the
Collateral Agent by virtue of the provisions of this Article, are authorized and
directed to treat and regard the Collateral Agent as the assignee and transferee
of the Mortgagor and entitled in the Mortgagor's place and stead to receive such
Hydrocarbons and all proceeds therefrom; and said parties and each of them shall
be fully protected in so treating and regarding the Collateral Agent and shall
be under no obligation to see to the application by the Collateral Agent of any
such proceeds or payments received by it. Notwithstanding the other provisions
of this Article including the foregoing provisions of this Section 3.1, the
Collateral Agent or any receiver appointed in judicial proceedings for the
enforcement of this instrument shall have the right to receive all of the
Hydrocarbons herein assigned and the proceeds therefrom only after any event of
default as described in the provisions of Section 4.1 hereof shall have occurred
and be continuing. Upon any sale of the Mortgaged Property or any part thereof
pursuant to Article V, the Hydrocarbons thereafter produced from the property so
sold, and the proceeds therefrom, shall be included in such sale and shall pass
to the purchaser free and clear of the assignment contained in this Article.

         3.2 Application of Proceeds. All payments received by the Collateral
Agent pursuant to Section 3.1 hereof shall be placed in a cash collateral
account at the principal office of the Collateral Agent and on the first
Business Day (as defined in the Credit Agreements) of each calendar month
applied as follows:

                  First: To the payment and satisfaction of all costs and
         expenses incurred in connection with the collection of such proceeds,
         and to the payment of all items of the Secured Indebtedness not
         evidenced by any Credit Agreement Note or any Indenture Note.

                  Second: To the payment of those items of the Secured
         Indebtedness then due and owing, pro rata according to each Secured
         Indebtedness holder's percentage of such items outstanding at the time
         of such payment.

                  Third:  The balance, if any, shall be released to the 
         Mortgagor.


                              Exhibit Q - Page 10
<PAGE>   63


         3.3 No Liability of the Collateral Agent in Collecting. The Collateral
Agent is hereby absolved from all liability for failure to enforce collection of
any proceeds so assigned (and no such failure shall be deemed to be a waiver of
any right of the Collateral Agent or the Trustees) and from all other
responsibility in connection therewith, except the responsibility to account to
the Mortgagor for funds actually received.

         3.4 Assignment Not a Restriction on the Collateral Agent's Rights.
Nothing herein contained shall detract from or limit the absolute obligation of
the Mortgagor to make payment of the Secured Indebtedness regardless of whether
the proceeds assigned by this Article are sufficient to pay the same, and the
rights under this Article shall be in addition to all other security now or
hereafter existing to secure the payment of the Secured Indebtedness.

         3.5 Indemnity. The Mortgagor agrees to indemnify the Trustees and the
Collateral Agent against all claims, actions, liabilities, judgments, costs,
attorneys' fees or other charges of whatsoever kind or nature (all hereinafter
in this Section 3.6 called "claims") made against or incurred by them or any of
them as a consequence of the assertion, either before or after the payment in
full of the Secured Indebtedness, that they or any of them received Hydrocarbons
herein assigned or the proceeds thereof claimed by third persons, and the
Trustees and the Collateral Agent shall have the right to defend against any
such claims, employing attorneys therefor, and unless furnished with reasonable
indemnity, they or any of them shall have the right to pay or compromise and
adjust all such claims. The Mortgagor will indemnify and pay to the Trustees or
the Collateral Agent, as the case may be, any and all such amounts as may be
paid in respect thereof or as may be successfully adjudged against the Trustees
or the Collateral Agent or any of them. The obligations of the Mortgagor as
hereinabove set forth in this Section 3.5 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

                                   ARTICLE IV
                                Events of Default

         4.1 Events of Default Hereunder. Default in the payment of principal of
any Secured Indebtedness when due or default (and such default shall continue
unremedied for five (5) days or such longer period during which the holders
thereof, or any Indenture Trustee for the holders thereof, do not have the power
to cause such Secured Indebtedness to become immediately payable in full) in the
payment of interest on any Secured Indebtedness when due, so long as such
default shall not have been remedied shall be an "event of default" hereunder.

                                    ARTICLE V
                           Enforcement of the Security

         5.1 Power of Sale of Real Property Constituting a Part of the Mortgaged
Property. Upon the occurrence of an event of default and if such event shall be
continuing, the Trustees shall have the right and power to sell, to the extent
permitted by law, at one or more sales, as an entirety or in parcels, as they
may elect, the real property constituting a part of the Mortgaged Property, at
such place or places and otherwise in such manner and upon such notice as may be
required by law, or, in the absence of any such requirement, as the Trustees may
deem appropriate, and to make conveyance to the purchaser or purchasers; and the
Mortgagor shall warrant title to such real property, subject to Permitted
Encumbrances, to such purchaser or purchasers. Any public sale may be adjourned
without the necessity of announcement




                              Exhibit Q - Page 11
<PAGE>   64

at the time and place of such sale and without public notice except as may be
required by law. The Trustee may sell, transfer and convey any part of the
Mortgaged Property on such terms of credit or part cash and part credit, secured
by contract or agreement for sale or mortgage, or otherwise as shall appear to
the Trustee to be most advantageous and for such price or prices as can
reasonably be obtained therefor, and in the event of a sale on credit or for
part cash or part credit, whether by way of contract for sale or by conveyance
or transfer and mortgage, neither the Trustee, nor Collateral Agent or holders
of Secured Indebtedness are to be accountable for or charged with any monies
until the same shall actually be received in cash. The right of sale hereunder
shall not be exhausted by one or any sale, and the Trustees may make other and
successive sales until all of the trust estate be legally sold. If the proceeds
of such sale or sales of less than the whole of the Mortgaged Property shall be
less than the aggregate of the indebtedness secured hereby and the expense of
executing this trust as provided herein, this Mortgage and the lien and charge
hereof shall remain in full force and effect as to the unsold portion of the
Mortgaged Property just as though no sale had been made; provided, however, that
the Mortgagor shall never have any right to require the sale of less than the
whole of the Mortgaged Property but the Collateral Agent shall have the right,
at its election, to request the Trustee to sell less than the whole of the
Mortgaged Property. With respect to that portion, if any, of the Mortgaged
Property situated in the State of Wyoming, this instrument may be foreclosed by
advertisement and sale as provided by applicable Wyoming statutes. With respect
to that portion, if any, of the Mortgaged Property situated in the State of
Oklahoma, the Collateral Agent shall have the right and power at its option to
declare the Secured Indebtedness hereby secured due and payable and to sell, or
direct the Trustees to sell, the "real estate," as such term is defined under
the provisions of 46 O.S. Supp. 1986, ss.42, constituting a part of the
Mortgaged Property, all under the terms of 46 O.S. Supp. 1986, ss.40 et seq.,
and shall, to the extent permitted by law, have the other rights conferred on
the Trustees under the provisions of this instrument.

         5.2 Rights of the Trustees with Respect to Personal Property
Constituting a Part of the Mortgaged Property. Upon the occurrence of an event
of default and if such event shall be continuing, the Trustees will have all
rights and remedies granted by law, and particularly by the Uniform Commercial
Code, including, but not limited to, the right to take possession of all
personal property constituting a part of the Mortgaged Property, and for this
purpose the Trustees may enter upon any premises on which any or all of such
personal property is situated and take possession of and operate such personal
property (or any portion thereof) or remove it therefrom. The Trustees may
require the Mortgagor to assemble such personal property and make it available
to the Trustees at a place to be designated by the Trustees which is reasonably
convenient to all parties. Unless such personal property is perishable or
threatens to decline speedily in value or is of a type customarily sold on a
recognized market, the Trustees will give the Mortgagor reasonable notice of the
time and place of any public sale or of the time after which any private sale or
other disposition of such personal property is to be made. This requirement of
sending reasonable notice will be met if the notice is mailed by first-class
mail, postage prepaid, to the Mortgagor at the address shown below the
signatures at the end of this instrument at least five (5) days before the time
of the sale or disposition.

         5.3 Rights of the Trustees with Respect to Fixtures Constituting a Part
of the Mortgaged Property. Upon the occurrence of an event of default and if
such event shall be continuing, the Trustees may elect to treat the fixtures
constituting a part of the Mortgaged Property as either real property collateral
or personal property collateral and then proceed to exercise such rights as
apply to such type of collateral.



                              Exhibit Q - Page 12
<PAGE>   65

         5.4 Judicial Proceedings. Upon occurrence of an event of default and if
such event shall be continuing, the Trustees, in lieu of or in addition to
exercising any power of sale hereinabove given, may proceed by a suit or suits
in equity or at law, whether for a foreclosure hereunder, or for the sale of the
Mortgaged Property, or for the specific performance of any covenant or agreement
herein contained or in aid of the execution of any power herein granted, or for
the appointment of a receiver pending any foreclosure hereunder or the sale of
the Mortgaged Property, or for the enforcement of any other appropriate legal or
equitable remedy.

         5.5 Possession of the Mortgaged Property. It shall not be necessary for
the Trustees to have physically present or constructively in their possession at
any sale held by the Trustees or by any court, receiver or public officer any or
all of the Mortgaged Property; and the Mortgagor shall deliver to the purchasers
at such sale on the date of sale the Mortgaged Property purchased by such
purchasers at such sale, and if it should be impossible or impracticable for any
of such purchasers to take actual delivery of the Mortgaged Property, then the
title and right of possession to the Mortgaged Property shall pass to such
purchaser at such sale as completely as if the same had been actually present
and delivered.

         5.6 Certain Aspects of a Sale. Each Lender or Noteholder shall have the
right to become the purchaser at any sale held by the Trustees or by any court,
receiver or public officer, and such Lender shall have the right to credit upon
the amount of the bid made therefor the amount payable out of the net proceeds
of such sale to it. Recitals contained in any conveyance made to any purchaser
at any sale made hereunder shall conclusively establish the truth and accuracy
of the matters therein stated, including, without limiting the generality of the
foregoing, nonpayment of the unpaid principal sum of, and the interest accrued
on, the Secured Indebtedness after the same have become due and payable,
advertisement and conduct of such sale in the manner provided herein or
appointment of any successor Trustee hereunder.

         5.7 Receipt to Purchaser. Upon any sale, whether made under the power
of sale herein granted and conferred or by virtue of judicial proceedings, the
receipt of the Trustees, or of the officer making sale under judicial
proceedings, shall be sufficient discharge to the purchaser or purchasers at any
sale for his or their purchase money, and such purchaser or purchasers, or his
or their assigns or personal representatives, shall not, after paying such
purchase money and receiving such receipt of the Trustees or of such officer
therefor, be obliged to see to the application of such purchase money, or be in
anywise answerable for any loss, misapplication or nonapplication thereof.

         5.8 Effect of Sale. Any sale or sales of the Mortgaged Property,
whether under the power of sale herein granted and conferred or by virtue of
judicial proceedings, shall operate to divest all right, title, interest, claim
and demand whatsoever either at law or in equity, of the Mortgagor of, in and to
the premises and the property sold, and shall be a perpetual bar, both at law
and in equity, against the Mortgagor, and the Mortgagor's successors or assigns,
and against any and all persons claiming or who shall thereafter claim all or
any of the property sold from, through or under the Mortgagor or the Mortgagor's
successors or assigns. Nevertheless, the Mortgagor, if requested by the Trustees
so to do, shall join in the execution and delivery of all proper conveyances,
assignments and transfers of the properties so sold.





                              Exhibit Q - Page 13
<PAGE>   66

         5.9 Application of Proceeds. The proceeds of any sale of the Mortgaged
Property, or any part thereof, whether under the power of sale herein granted
and conferred or by virtue of judicial proceedings, shall be applied as follows:

                  First: To the payment and satisfaction of all reasonable costs
         and expenses incurred by the Trustees in the performance of their
         duties including, without limiting the generality of the foregoing,
         costs and expenses of any entry, or taking of possession, of any sale,
         or advertisement thereof, and of conveyances, and as well, court costs,
         compensation of agents and employees and reasonable legal fees.

                  Second: To a payment to the Collateral Agent, equal in amount
         to the Secured Indebtedness outstanding at the time of the payment.

                  Third: Any surplus thereafter remaining shall be paid to the
         Mortgagor or the Mortgagor's successors or assigns, as their interests
         shall appear.

         All payments to the Collateral Agent shall be paid into such account as
the Collateral Agent shall specify from time to time by notice to the Trustees,
in same day or immediately available funds. The Collateral Agent shall promptly
remit in same day funds to each holder of Secured Indebtedness its pro rata
share, based on the amount of outstanding Secured Indebtedness owed to it, of
such payments received by the Collateral Agent.

         5.10 The Mortgagor's Waiver of Appraisement, Marshalling and Other
Rights. The Mortgagor agrees, to the full extent that the Mortgagor may lawfully
so agree, that the Mortgagor will not at any time insist upon or plead or in any
manner whatever claim the benefit of any appraisement, valuation, stay,
extension or redemption law now or hereafter in force, in order to prevent or
hinder the enforcement or foreclosure of this instrument or the absolute sale of
the Mortgaged Property or the possession thereof by any purchaser at any sale
made pursuant to any provision hereof, or pursuant to the decree of any court of
competent jurisdiction; but the Mortgagor, for the Mortgagor and all who may
claim through or under the Mortgagor, so far as the Mortgagor or those claiming
through or under the Mortgagor now or hereafter lawfully may, hereby waives the
benefit of all such laws; provided, however, that appraisement of any of the
Mortgaged Property located in the State of Oklahoma is hereby expressly waived
or not, at the option of the Trustees, such option to be exercised prior to or
at the time the judgment is rendered in any foreclosure hereof. The Mortgagor,
for the Mortgagor and all who may claim through or under the Mortgagor, waives,
to the extent that the Mortgagor may lawfully do so, any and all right to have
the Mortgaged Property marshalled upon any foreclosure of the lien hereof, or
sold in inverse order of alienation, and agrees that the Trustees or any court
having jurisdiction to foreclose such lien may sell the Mortgaged Property as an
entirety. The Mortgagor, for the Mortgagor and all who may claim through or
under the Mortgagor, further waives, to the full extent that the Mortgagor may
lawfully do so, any requirement for posting a receiver's bond or replevin bond
or other similar type of bond if the Trustees commence an action for appointment
of a receiver or an action for replevin to recover possession of any of the
Mortgaged Property. If any law in this paragraph referred to and now in force,
of which the Mortgagor or the Mortgagor's successor or successors might take
advantage despite the provisions hereof, shall hereafter be repealed or cease to
be in force, such law shall not thereafter be deemed to constitute any part of
the contract herein contained or to preclude the operation or application of the
provisions of this 




                              Exhibit Q - Page 14
<PAGE>   67

paragraph. Pursuant to Section 39-5-19, New Mexico Statutes, Annotated, 1978
Comp., as amended, the Mortgagor agrees that as to the Mortgaged Property
situated in the State of New Mexico, the redemption period shall be shortened to
one (1) month. The Mortgagor hereby waives all rights of appraisement, sale,
homestead or redemption allowed under any law or laws of the State of Arkansas,
and especially redemption under the Act of the General Assembly of the State of
Arkansas approved May 8, 1899, and acts amendatory thereto.

         5.11 Costs and Expenses. All reasonable costs and expenses (including
reasonable attorneys' fees) incurred by the Trustees and the Collateral Agent in
protecting and enforcing their rights hereunder, shall constitute a demand
obligation owing by the Mortgagor to the party incurring such costs and expenses
and shall draw interest at an annual rate equal to the "Prime Rate" (the "Prime
Rate") as published in the Wall Street Journal from time to time (or if for a
day when such rate is note so published, at the rate for the next preceding day
when so published) from time to time plus two percent (2%) until paid, all of
which shall constitute a portion of the Secured Indebtedness.

         5.12 Sale of the Mortgaged Property in Mississippi. After the
occurrence of an event of default, the Trustees, their successors or
substitutes, are authorized and empowered, and it shall be their special duty at
the request of the Collateral Agent (which request is hereby presumed), to
enforce this trust and to sell the Mortgaged Property located in the State of
Mississippi, as an entirety or in parcels, as the Trustees acting may designate,
to satisfy the Secured Indebtedness then unpaid, after having published notice
of the day, time, place and terms of sale in some newspaper published in the
county or counties, as the case may be, in which the Mortgaged Property in the
State of Mississippi is situated for three (3) consecutive weeks preceding date
of sale, and by posting one notice of such sale at the Court House of each
county in which the Mortgaged Property is situated for said period of time. In
the event the Mortgaged Property is located in more than one county or in two
judicial districts of the same county in the State of Mississippi, the Trustees
or their substitutes or successors in trust shall have the power, in case they
are directed to foreclose under this instrument, to select the county or
judicial district in which the sale shall be made and their selection shall be
binding on the Mortgagor and the holders of Secured Indebtedness and all persons
claiming through or under them, whether by contract or law. The Trustees or
their substitutes or any successors in said Trust shall have full power to fix
the day, time, place and terms of sale and may appoint or delegate any one or
more persons as agent to perform any act or acts necessary or incident to any
sale held by the Trustees, including the posting of notices and the conduct of
sale, but in the name and on behalf of the Trustees, their substitutes or
successors. The Mortgagor waives the provisions of Section 89-1-55 of the
Mississippi Code of 1972, Recompiled, and Laws amendatory thereto, if any, as
far as said section restricts the right of the Trustees to offer at sale more
than 160 acres at one time, and the Trustees, their substitutes or successors
may, in their discretion, offer the Mortgaged Property as a whole or in such
part or parts as they may deem desirable, regardless of the manner in which it
may be described. Any sale made by the Trustees hereunder may be adjourned by
announcement at the time and place appointed for such sale without further
notice except as may be required by law.

         5.13 Sale of the Mortgaged Property in Texas. If any Credit Agreement
Note or any Indenture Note is not paid when due, whether by acceleration or
otherwise, the Trustees are hereby authorized and empowered to sell any part of
the Mortgaged Property located in the State of Texas at public sale to the
highest bidder for cash in the area at the county courthouse of the county in
Texas in which the Texas portion of the Mortgaged Property or any part thereof
is situated, as herein described, designated by such




                              Exhibit Q - Page 15
<PAGE>   68

county's commissioner's court for such proceedings, or if no area is so
designated, at the door of the county courthouse of said county, at a time
between the hours of 10:00 A.M. and 4:00 P.M. which is no later than three (3)
hours after the time stated in the notice described immediately below as the
earliest time at which such sale would occur on the first Tuesday of any month,
after advertising the earliest time at which said sale would occur, the place,
and terms of said sale, and the portion of the Mortgaged Property to be sold, by
(a) posting (or by having some person or persons acting for the Trustees post)
for at least twenty-one (21) days preceding the date of the sale, written or
printed notice of the proposed sale at the courthouse door of said county in
which the sale is to be made; and if such portion of the Mortgaged Property lies
in more than one county, one such notice of sale shall be posted at the
courthouse door of each county in which such part of the Mortgaged Property is
situated and such part of the Mortgaged Property may be sold in the area at the
county courthouse of any one of such counties designated by such county's
commissioner's court for such proceedings, or if no area is designated, at the
courthouse door of such county, and the notice so posted shall designate in
which county such property shall be sold, and (b) filing in the office of the
county clerk of each county in which any part of the Texas portion of the
Mortgaged Property which is to be sold at such sale is situated a copy of the
notice posted in accordance with the preceding clause (a). In addition to such
posting and filing of notice, the Collateral Agent, acting on behalf of the
holders of the Secured Indebtedness shall, at least twenty-one (21) days
preceding the date of sale, serve or cause to be served written notice of the
proposed sale by certified mail on the Mortgagor and on each other debtor, if
any, obligated to pay the Secured Indebtedness according to the records of the
Collateral Agent, the Lenders, the Noteholders or other holders of the Secured
Indebtedness. Service of such notice shall be completed upon deposit of the
notice, enclosed in a postpaid wrapper properly addressed to the Mortgagor and
such other debtors at their most recent address or addresses as shown by the
records of the Collateral Agent in a post office or official depository under
the care and custody of the United States Postal Service. The affidavit of any
person having knowledge of the facts to the effect that such a service was
completed shall be prima facie evidence of the fact of service. The Mortgagor
agrees that no notice of any sale, other than as set out in this paragraph, need
be given by the Trustees, the Collateral Agent or any other person. The
Mortgagor hereby designates as its address for the purpose of such notice the
address set out on the signature page hereof; and agrees that such address shall
be changed only by depositing notice of such change enclosed in a postpaid
wrapper in a post office or official depository under the care and custody of
the United States Postal Service, certified mail, postage prepaid, return
receipt requested, addressed to the Collateral Agent at the address for the
Collateral Agent set out herein (or to such other address as the Collateral
Agent may have designated by notice given as above provided to the Mortgagor and
such other debtors). Any such notice of change of address of the Mortgagor or
other debtors or of the Collateral Agent shall be effective three (3) Business
Days after such deposit if such post office or official depository is located in
the State of Texas, otherwise to be effective upon receipt. The Mortgagor
authorizes and empowers the Trustees to sell the Texas portion of the Mortgaged
Property in lots or parcels or in its entirety as the Trustees shall deem
expedient; and to execute and deliver to the purchaser or purchasers thereof
good and sufficient deeds of conveyance thereto by fee simple title, with
evidence of general warranty by the Mortgagor, and the title of such purchaser
or purchasers when so made by the Trustees, the Mortgagor binds itself to
warrant and forever defend. Where portions of the Mortgaged Property lie in
different counties, sales in such counties may be conducted in any order that
the Trustees may deem expedient; and one or more such sales may be conducted in
the same month, or in successive or different months as the Trustees may deem
expedient. Notwithstanding anything to the contrary contained herein, the
Trustees may postpone the sale provided for in this Section 5.13 at any time
without the necessity of a public announcement. The provisions hereof 



                              Exhibit Q - Page 16
<PAGE>   69

with respect to the posting and giving of notices of sale are intended to comply
with the provisions of Section 51.002 of the Property Code of the State of
Texas, as in force and effect on January 1, 1992, and in the event the
requirements, or any notice, under such Section 51.002 of the Property Code of
the State of Texas shall be eliminated or the prescribed manner of giving such
notices modified by future amendment to, or adoption of any statute superseding,
Section 51.002 of the Property Code of the State of Texas, the requirement for
such particular notices shall be deemed stricken from or modified in this
instrument in conformity with such amendment or superseding statute, effective
as of the effective date thereof.

         5.14 Operation of the Mortgaged Property by the Trustees. Upon the
occurrence of an event of default and so long as such event of default is
continuing and in addition to all other rights herein conferred on the Trustees,
the Trustees (or any person, firm or corporation designated by the Trustees)
shall have the right and power, but shall not be obligated, to enter upon and
take possession of any of the Mortgaged Property, and to exclude the Mortgagor,
and the Mortgagor's agents or servants, wholly therefrom, and to hold, use,
administer, manage and operate the same to the extent that the Mortgagor shall
be at the time entitled and in its place and stead. The Trustees, or any person,
firm or corporation designated by the Trustees, may operate the same without any
liability to the Mortgagor in connection with such operations, except to use
ordinary care in the operation of such properties, and the Trustees or any
person, firm or corporation designated by the Trustees, shall have the right to
collect, receive and receipt for all Hydrocarbons produced and sold from said
properties, to make repairs, purchase machinery and equipment, conduct work-over
operations, drill additional wells and to exercise every power, right and
privilege of the Mortgagor with respect to the Mortgaged Property. When and if
the expenses of such operation and development (including costs of unsuccessful
work-over operations or additional wells) have been paid and the Secured
Indebtedness paid, said properties shall, if there has been no sale or
foreclosure, be returned to the Mortgagor.

                                   ARTICLE VI
                            Miscellaneous Provisions

         6.1 Successor Trustees. Any Trustee may resign in writing addressed to
the Collateral Agent or may be removed at any time with or without cause by an
instrument in writing duly executed by the Collateral Agent. In case of the
death, resignation or removal of a Trustee, one or more successor Trustees may
be appointed by the Collateral Agent by instrument of substitution complying
with any applicable requirements of law, and in the absence of any such
requirement without formality other than appointment and designation in writing.
Such appointment and designation shall be full evidence of the right and 
authority to make the same and of all facts therein recited, and upon the making
of any such appointment and designation this conveyance shall vest in the named
successor Trustee or Trustees all the estate and title of the prior Trustee in
all of the Mortgaged Property, and he or they shall thereupon succeed to all the
rights, powers, privileges, immunities and duties hereby conferred upon the
prior Trustee. All references herein to the Trustees shall be deemed to refer to
the Trustees from time to time acting hereunder.

         6.2 Actions or Advances by the Collateral Agent or the Trustees. Each
and every covenant herein contained shall be performed and kept by the Mortgagor
solely at the Mortgagor's expense. If the Mortgagor shall fail to perform or
keep any of the covenants of whatsoever kind or nature contained in this
instrument, the Collateral Agent, the Trustees or any receiver appointed
hereunder, may, but shall not be




                              Exhibit Q - Page 17
<PAGE>   70

obligated to, take action and/or make advances to perform the same in the
Mortgagor's behalf, and the Mortgagor hereby agrees to repay the expense of such
action and such advances upon demand plus interest at an annual rate equal to
the Prime Rate plus two percent (2%) until paid or, in the event any promissory
note evidences such indebtedness, upon the terms and conditions thereof. No such
advance or action by the Collateral Agent, the Trustees or any receiver
appointed hereunder shall be deemed to relieve the Mortgagor from any default
hereunder.

         6.2 Defense of Claims. The Mortgagor will notify the Trustees, in
writing, promptly of the commencement of any legal proceedings affecting the
lien or security interest hereof or the Mortgaged Property, or any part thereof,
and will take such action, employing attorneys agreeable to the Trustees and the
Collateral Agent, as may be necessary or appropriate to preserve the
Mortgagor's, the Trustees' and the Collateral Agent's rights affected thereby
and/or to hold harmless the Trustees or the Collateral Agent in respect of such
proceedings; and should the Mortgagor fail or refuse to take any such action,
the Trustees or the Collateral Agent may, upon giving prior written notice
thereof to the Mortgagor, take such action in behalf and in the name of the
Mortgagor and at the Mortgagor's expense. The obligations of the Mortgagor as
hereinabove set forth in this Section 6.3 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

         6.3 The Mortgaged Property to Revert. If the Secured Indebtedness shall
be fully paid and all the commitments and obligations of the Lenders under the
Credit Agreements shall have been terminated in writing and the covenants herein
contained and contained in the Credit Agreements shall be well and truly
performed, then all of the Mortgaged Property shall revert to the Mortgagor and
the entire estate, right, title and interest of the Trustees and the holders of
Secured Indebtedness shall thereupon cease; and the Trustees and the Collateral
Agent in such case shall, upon the request of the Mortgagor and at the
Mortgagor's cost and expense, deliver to the Mortgagor proper instruments
acknowledging satisfaction of this instrument. The foregoing notwithstanding,
this instrument is a Line of Credit Mortgage and until the termination in
writing of the Credit Agreements and the occurrence of the other events
described in the past sentence of this Section, this Mortgage, and the priority
and perfection of the liens created hereunder should continue in full force and
effect even if at any time or from time to time there are no moneys outstanding
under the Credit Agreements.

         6.4 Renewals, Amendments and Other Security. Renewals and extensions of
the Secured Indebtedness may be given at any time and amendments may be made to
agreements relating to any part of such Secured Indebtedness or the Mortgaged
Property and the Trustees and the holders of Secured Indebtedness may take or
may now hold other security for the Secured Indebtedness, all without notice to
or consent of the Mortgagor. The Trustees or the holders of Secured Indebtedness
may resort first to such other security or any part thereof or first to the
security herein given or any part thereof, or from time to time to either or
both, even to the partial or complete abandonment of either security, and such
action shall not be a waiver of any rights conferred by this instrument, which
shall continue as a first lien upon and prior perfected security interest in the
Mortgaged Property not expressly released until the Secured Indebtedness is
fully paid.

         6.5 Instrument an Assignment, etc. This instrument shall be deemed to
be and may be enforced from time to time as an assignment, chattel mortgage,
contract, deed of trust, financing statement, real estate mortgage, or security
agreement, and from time to time as any one or more thereof.





                              Exhibit Q - Page 18
<PAGE>   71

         6.6 Limitation on Interest. No provision of this instrument shall
require the payment or permit the collection of interest in excess of the
maximum permitted by applicable law or which is otherwise contrary to law. If
any excess of interest in such respect is herein provided for, or shall be
adjudicated to be so provided for herein, the Mortgagor shall not be obligated
to pay such excess.

         6.7 Unenforceable or Inapplicable Provisions. If any provision hereof
is invalid or un enforceable in any jurisdiction, the other provisions hereof
shall remain in full force and effect in such jurisdiction, and the remaining
provisions hereof shall be liberally construed in favor of the Trustees and the
Collateral Agent in order to effectuate the provisions hereof, and the
invalidity of any provision hereof in any jurisdiction shall not affect the
validity or enforceability of any such provision in any other jurisdiction. Any
reference herein contained to a statute or law of a state in which no part of
the Mortgaged Property is situated shall be deemed inapplicable to, and not used
in, the interpretation hereof.

         6.8 Rights Cumulative. Each and every right, power and remedy herein
given to the Trustees or the Collateral Agent shall be cumulative and not
exclusive; and each and every right, power and remedy whether specifically
herein given or otherwise existing may be exercised from time to time and so
often and in such order as may be deemed expedient by the Trustees and the
Collateral Agent, as the case may be, and the exercise, or the beginning of the
exercise, of any such right, power or remedy shall not be deemed a waiver of the
right to exercise, at the same time or thereafter, any other right, power or
remedy. No delay or omission by the Trustees or the Collateral Agent or any of
them in the exercise of any right, power or remedy shall impair any such right,
power or remedy or operate as a waiver thereof or of any other right, power or
remedy then or thereafter existing. [In addition to all the rights and remedies
granted hereunder, the Mortgagor agrees to comply with all statutory mortgage
covenants and agree that this Mortgage shall be subject to the statutory
mortgage condition.](1)

         6.9 Waiver by the Trustees. Any and all covenants in this instrument
may from time to time by instrument in writing signed by the Trustees be waived
to such extent and in such manner as the Trustees may desire, but no such waiver
shall ever affect or impair either the Trustees' or the Collateral Agent's
rights or liens or security interests hereunder, except to the extent
specifically stated in such written instrument.

         6.10 Action by Individual Trustee. Any Trustee from time to time
serving hereunder shall have the absolute right, acting individually, to take
any action and to give any consent and to exercise any right, remedy, power,
privilege or authority conferred upon the Trustees, and any action taken by
either Trustee from time to time serving hereunder shall be binding upon the
other Trustee and no person dealing with either Trustee from time to time
serving hereunder shall be obligated to confirm the power and authority of such
Trustee to act without the concurrence of the other Trustee. In this instrument,
the term "Trustee" shall mean the Trustees hereinabove named, or either of them,
as the context requires, and any successor Trustee.

         6.11 Miscellaneous Warranties. The Mortgagor additionally warrants and
represents to the Trustees and the Collateral Agent that (a) the execution and
delivery of this instrument, and the


- ---------------------
         (1)       To be used in Mortgages to be filed in New Mexico.


                              Exhibit Q - Page 19
<PAGE>   72

performance by the Mortgagor of its obligations hereunder, are within the
corporate, partnership or other powers of the Mortgagor and have been duly
authorized by all necessary corporate, partnership or other action on the part
of the Mortgagor, and (b) this instrument has been duly executed and delivered
on behalf of the Mortgagor and is the legal, valid and binding obligation of the
Mortgagor, enforceable in accordance with its terms except as such
enforceability is subject to the effect of (i) any applicable bankruptcy,
insolvency, reorganization or similar laws relating to or affecting creditors'
rights generally and (ii) general principles of equity (regardless of whether
such enforceability is considered in a proceeding in equity or at law, including
without limitation, concepts of materiality, reasonableness, good faith and fair
dealing, and (c) the execution, delivery and performance of this instrument do
not and will not contravene or conflict with the organizational documents of the
Mortgagor or, to the best knowledge of the Mortgagor, violate or constitute a
default under any law, any presently existing requirement or restriction imposed
by judicial, arbitral or any governmental instrumentality.

         6.12 Successors and Assigns. This instrument is binding upon the
Mortgagor, the Mortgagor's successors and assigns, and shall inure to the
benefit of the Trustees, their successors, and the Collateral Agent, its
successors and assigns, and the provisions hereof shall likewise be covenants
running with the land.

         6.13 Article and Section Headings. The article and section headings in
this instrument are inserted for convenience of reference and shall not be
considered a part of this instrument or used in its interpretation.

         6.14 Execution in Counterparts. This instrument may be executed in any
number of counterparts, each of which shall for all purposes be deemed to be an
original and all of which are identical, except that, to facilitate recordation
or filing, in any particular counterpart portions of Exhibit A hereto which
describe properties situated in counties other than the county in which such
counterpart is to be recorded or filed may have been omitted.

         6.15 Special Filing as Financing Statement. This Mortgage and Deed of
Trust shall likewise be a Security Agreement and a Financing Statement. This
Mortgage and Deed of Trust shall be filed for record, among other places, in the
real estate records of each county in which any portion of the real property
covered by the oil and gas leases described in Exhibit A hereto is situated,
and, when filed in such counties shall be effective as a financing statement
covering fixtures located on oil and gas properties, which oil and gas
properties (and accounts arising therefrom) are to be financed at the wellheads
of the wells located on the real property described in Exhibit A hereto. At the
option of the Collateral Agent, a carbon, photographic or other reproduction of
this instrument or of any financing statement covering the Mortgaged Property or
any portion thereof shall be sufficient as a financing statement and may be
filed as such.

         6.16 Notices. Except as otherwise specifically provided for herein, all
notices, demands, instructions and other communications required or permitted to
be given to or made upon any party hereto shall be in writing and shall be
personally delivered or sent by certified mail, postage prepaid, return receipt
requested, or by telecopier, and shall be deemed to be given for purposes of
this instrument on the day that such writing is delivered or sent to the
intended recipient thereof in accordance with the provisions of this Section
6.16. Unless otherwise specified in a notice sent or delivered in accordance
with the foregoing




                              Exhibit Q - Page 20
<PAGE>   73

provisions of this Section 6.16, notices, demands, instructions and other
communications in writing shall be given to or made upon the respective parties
hereto at their respective addresses (or to their respective telecopier numbers)
indicated on the signature page(s) hereof.

         6.17 Release Upon Disposition; Termination.

         (a) From time to time during the term of this Agreement, unless an
event of default shall have occurred and be continuing, the Trustees and the
Collateral Agent shall execute, acknowledge and deliver to the Mortgagor a
release from this instrument of Mortgaged Properties in connection with the
sale, transfer or other disposition of such Mortgaged Properties by the
Mortgagor, other than a sale, transfer or disposition to Borrower or any
Subsidiary of Borrower and other than the mortgaging, pledging, securing or
granting of a lien, mortgage or security interest in the Mortgaged Properties to
any of them. Upon the receipt by the Collateral Agent of an Officer's
Certificate certifying that no event of default has occurred and is continuing
and that certain Mortgaged Properties described in such Officer's Certificate,
or an attachment thereto, are to be sold, transferred or disposed of by the
Mortgagor pursuant to a bona fide agreement, other than a sale, transfer or
disposition to Borrower or any Subsidiary of Borrower and other than the
mortgaging, pledging, securing or granting of a lien, mortgage or security
interest in the Mortgaged Properties to any of them, the Collateral Agent shall
execute, acknowledge and deliver to the Mortgagor an appropriate instrument
evidencing such release of such Mortgaged Property in such form as may be
reasonably requested by the Mortgagor. The Trustees shall execute, acknowledge
and deliver to the Mortgagor, and the purchaser or other transferee shall be to
rely conclusively on, any such instrument of release of Mortgaged Properties
which bears the signature of the Collateral Agent without any further inquiry.
It is expressly understood that any such release may be delivered to the
Mortgagor prior to the actual sale, transfer or disposition to facilitate such
transaction, provided that such release shall be canceled and redelivered to the
Collateral Agent if such Mortgaged Properties are not so sold, transferred or
disposed of within 20 days after the date such release has been fully executed,
acknowledged and delivered to the Mortgagor. As used herein, the term "Officer's
Certificate" means a certificate signed by the Chairman of the Board, the
President, any Executive Vice President, or the Chief Financial Officer of the
Mortgagor, and the term "Subsidiary" of Borrower means an entity of which more
than 50% of the securities entitled to normal voting power are owned directly,
or indirectly through one or more other Subsidiaries, by Borrower.

         (b) The Trustee and the Collateral Agent shall execute, acknowledge and
deliver to the Mortgagor a termination of this instrument and full release of
all the Mortgaged Properties upon receipt of a notice or other writing signed by
the Administrative Agent under the Primary Credit Agreement, stating that this
instrument is no longer required to be maintained pursuant to the terms of the
Primary Credit Agreement. Such termination of this instrument and full release
of all the Mortgaged Properties shall be evidenced by an instrument in such form
as may be reasonably requested by the Mortgagor, which will be executed,
acknowledged and delivered by the Trustees and the Collateral Agent with
reasonable promptness following receipt of such notice or other writing signed
by the Administrative Agent.

         [6.18 North Dakota Provisions. THE PARTIES AGREE THAT THIS MORTGAGE 
CONSTITUTES A COLLATERAL REAL ESTATE MORTGAGE PURSUANT TO NORTH DAKOTA CENTURY
CODE CHAPTER 35-03.]



                              Exhibit Q - Page 21
<PAGE>   74

         [6.19 New Mexico Mortgage. With respect to the Mortgaged Property
located in the State of New Mexico, this Mortgage shall be construed as a
Mortgage and will be subject to foreclosure by law upon, among others, the
occurrence of any event of default.](1)

















- ------------------------
        (1)       To be used in Mortgages to be filed in New Mexico.




                              Exhibit Q - Page 22
<PAGE>   75




         IN WITNESS WHEREOF, the Mortgagor has executed or caused to be executed
this Mortgage, Deed of Trust, Assignment, Security Agreement and Financing
Statement on the day, month and year first above written.

                                           MORTGAGOR


                                           ----------------------------------

                                           By:
                                              -------------------------------
ATTEST:                                    Title:
                                           Printed Name:



- ---------------------
Secretary
Printed Name:





The name and mailing address of the Mortgagor is:


- -------------------
c/o PIONEER NATURAL RESOURCES COMPANY
1400 Williams Square West
5205 North O'Connor Blvd.
Irving, Texas 75039





                       (Signatures Continued on Next Page)





                              Exhibit Q - Page 23
<PAGE>   76



                                      SECURED PARTIES


                                      ----------------------------------------
                                                        , Trustee
                                      ------------------       

                                      ----------------------------------------
                                                        , Trustee
                                      ------------------       


                                                           , as Collateral Agent
                                      --------------------  

                                      By:
                                         -------------------------------------
ATTEST:                               Name:
                                      Printed Name:

- ----------------
Title:
Printed Name:

The names and mailing addresses of the Secured Parties are:

                                        , as Collateral Agent
- ----------------------------------------
                , Trustee and            , Trustee
- ----------------              ----------- 

- -----------------------------------------

- -----------------------------------------

This Instrument Was Prepared By:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, Texas  77002

[signature]

[SIGNED IN THE PRESENCE OF:


- ----------------
                ]
- ----------------




                              Exhibit Q - Page 24
<PAGE>   77



STATE OF TEXAS                      )
                                    )  Section.
COUNTY OF HARRIS                    )

          BE IT REMEMBERED that I,______________ , a Notary Public duly 
qualified, commissioned, sworn and acting in and for the County and State
aforesaid, hereby certify that, on this___day of_____, ______, there appeared
before me severally each of the following persons__________________,
the__________, and _____________ __________, the Secretary, of
_______________________, a _____________, whose address is 1400 Williams Square
West, 5205 North O'Connor Blvd., Irving, Texas 75039.

          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers with full authority, executed
                           the same voluntarily for and as the act of said
                           corporation.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation set forth opposite their names above and
                           were duly authorized in their respective capacities
                           to execute the foregoing instrument for and in the
                           name and on behalf of said corporation, and further
                           stated and acknowledged that they had so signed,
                           executed and delivered said foregoing instrument for
                           the consideration, uses and purposes therein
                           mentioned and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers of the corporation that executed the
                           above instrument on behalf of said corporation and
                           acknowledged to me that such corporation executed the
                           same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.



                              Exhibit Q - Page 25
<PAGE>   78




KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation set opposite his name, on behalf of said
                           corporation.

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation set opposite their names
                           on behalf of said corporation.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their names of Pogo
                           Producing Company, a Delaware corporation, on behalf
                           of said corporation [in its capacity as general
                           partner of Pogo Gulf Coast, Ltd., a Texas limited
                           partnership, on behalf of said partnership].

NORTH
DAKOTA                     Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation set opposite their names which executed
                           the foregoing instrument, signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation as such officers, respectively; that the
                           same is their free act and deed as such officers,
                           respectively, and the free and corporate act and deed
                           of the corporation set opposite their names; that
                           they were duly authorized thereupon by the board of
                           directors of said corporation; and that (as the case
                           may be) the seal affixed to said instrument is the
                           corporate seal of said corporation.

OKLAHOMA                   Before me on this day personally appeared the 
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation set opposite his name
                           for the uses and purposes therein set forth.



                              Exhibit Q - Page 26
<PAGE>   79




SOUTH                      DAKOTA Before me personally appeared each such
                           person, who acknowledged himself to be the designated
                           officer of the corporation set opposite his name, as
                           the case may be, and that as such designated officer
                           being authorized so to do, he executed the foregoing
                           instrument for the purposes therein contained, by
                           signing the name of said corporation by himself as
                           such designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation set opposite his name on behalf of
                           said corporation set opposite his name.

UTAH                       On this day personally appeared before me such 
                           persons, who, being by me duly sworn, did say, that
                           they are the designated officers of said corporation,
                           and that said instrument was signed in behalf of said
                           corporation by resolution of its Board of Directors,
                           and said persons acknowledged to me that the said
                           corporation, executed the same.

WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.

         GIVEN under my hand and seal this___day of_________________.



                                                   ---------------------    
                                                   Notary Public in and for
                                                   Harris County, TEXAS


                                                   ---------------------
                                                   Print or Type Name


My commission expires:






                              Exhibit Q - Page 27
<PAGE>   80




STATE OF____          )
                      )  Sections.
COUNTY OF____         )

                  BE IT REMEMBERED that I,______________, a Notary Public duly
qualified, commissioned, sworn and acting in and for the County and State
aforesaid, hereby certify that, on this___day of_________,________, there
appeared before me severally each of the following persons, each being either a
Trustee or else the designated officer of the corporation or association set
opposite his name, and each such Trustee, corporation or association being a
party to the foregoing instrument:

                  _______________,_____________and______,______of____________,
         a______________, whose address is_________________________;

                  __________________and________________whose addresses
         are____________, as Trustees.


          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers or Trustees with full
                           authority, executed the same voluntarily for and as
                           the act of said corporation, said association or said
                           Trustees, as the case may be.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation or association set forth opposite their
                           names above (or, in the case of the Trustees, were
                           validly appointed Trustees) and were duly authorized
                           in their respective capacities to execute the
                           foregoing instrument for and in the name and on
                           behalf of said corporation or association (or as
                           Trustees, as the case may be), and further stated and
                           acknowledged that they had so signed, executed and
                           delivered said foregoing instrument for the
                           consideration, uses and purposes therein mentioned
                           and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation or association, or himself, as Trustee,
                           as the case may be.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers (or Trustees, as the case may be) of
                           the 





                              Exhibit Q - Page 28
<PAGE>   81

                           corporation or the association that executed the
                           above instrument on behalf of said corporation or
                           association (or themselves, as Trustees) and
                           acknowledged to me that such corporation, association
                           or Trustees executed the same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.

KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation or association set opposite his name (or
                           a Trustee, as the case may be), on behalf of said
                           corporation or association (or of himself, as a
                           Trustee, as the case may be).

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation or association described in and that
                           executed the within instrument (or a Trustee, as the
                           case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation or association set
                           opposite their names (or as Trustees, as the case may
                           be) on behalf of said corporation or association, or
                           himself as a Trustee, as the case may be.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their
                           names,_____________of, a_______________ on behalf of
                           said___________[(or individually as trustees,
                           residing at _________________as the case may be, on
                           behalf of himself, as a Trustee)] [(or as the
                           designated officer of the Trustee set opposite their
                           respective names, of ___________, a____________,
                           and_____________, a___________, respectively on
                           behalf of said corporation or association, as
                           trustee)].(1)

- ----------------------------
         (1)      Modify as necessary for individual or corporate trustees.


                              Exhibit Q - Page 29
<PAGE>   82



NORTH DAKOTA               Before me personally appeared each such
                           person, each of whom is known to me to be the officer
                           of the corporation or association described in and
                           that executed the within instrument (or a Trustee, as
                           the case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation or association set opposite their names
                           which executed the foregoing instrument (or as
                           Trustees, as the case may be), signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation or association as such officers,
                           respectively (or as Trustees, as the case may be);
                           that the same is their free act and deed as such
                           officers, respectively (or as Trustees as the case
                           may be), and (as the case may be) the free and
                           corporate act and deed of the corporation or
                           association set opposite their names; that (as the
                           case may be) they were duly authorized there unto by
                           the board of directors of said corporation or
                           association; and that (as the case may be) the seal
                           affixed to said instrument is the corporate seal of
                           said corporation or association.

OKLAHOMA                   Before me on this day personally appeared the 
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation or association set
                           opposite his name (or of himself as Trustee, as the
                           case may be) for the uses and purposes therein set
                           forth.

SOUTH                      DAKOTA Before me personally appeared each such
                           person, who acknowledged himself to be the designated
                           officer of the corporation or association set
                           opposite his name, or a Trustee, as the case may be,
                           and that (as the case may be, as such designated
                           officer being authorized so to do) he executed the
                           foregoing instrument for the purposes therein
                           contained, by (as the case may be) signing the name
                           of said corporation or association by himself as such
                           designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation or association set opposite his name
                           (or a Trustee, as the case may be), on behalf of said
                           corporation or association set opposite his name (or
                           of himself as Trustee, as the case may be).

UTAH                       On this day personally appeared before me such 
                           persons, who, being by me duly sworn, did say, that
                           (as the case may be) they are the designated officers
                           of said corporation or association or are Trustees
                           and that said instrument was signed (as the case may
                           be) in behalf of said corporation or association by
                           resolution of its Board of Directors (or on behalf of
                           themselves as Trustees, as the case may be), and said
                           persons acknowledged to me that said corporation,
                           association or Trustees executed the same.




                              Exhibit Q - Page 30
<PAGE>   83

WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.


              GIVEN under my hand and seal this__day of_____________.


                                             -----------------------
                                             Notary Public in and for
                                                         County,
                                             ------------       ---------

                                             ---------------------
                                             Print or Type Name

My commission expires:















                              Exhibit Q - Page 31
<PAGE>   84

                EXHIBIT A To Mortgage, Deed of Trust, Assignment,
                Security Agreement and Financing Statement, dated
                      ______,______, from__________________
                          to___________ and____________
                              and________________,
                               as Collateral Agent

                               List of Properties

                        [to be prepared by the Mortgagor]


         1. Depth limitations, unit designations, unit tract descriptions and
descriptions of undivided leasehold interests, well names, "Operating
Interests", "Working Interests" and "Net Revenue Interests" contained in this
Exhibit A and the listing of any percentage, decimal or fractional interest in
this Exhibit A shall not be deemed to limit or otherwise diminish the interests
being subjected to the lien, security interest and encumbrance of this
instrument.

         2. Some of the land descriptions in this Exhibit A may refer only to a
portion of the land covered by a particular lease. This instrument is not
limited to the land described in Exhibit A but is intended to cover the entire
interest of the Mortgagor in any lease described in Exhibit A even if such
interest relates to land not described in Exhibit A. Reference is made to the
land descriptions contained in the documents of title recorded as described in
this Exhibit A. To the extent that the land descriptions in this Exhibit A are
incomplete, incorrect or not legally sufficient, the land descriptions contained
in the documents so recorded are incorporated herein by this reference.

         3. References in Exhibit A to instruments on file in the public records
are made for all purposes. Unless provided otherwise, all recording references
in Exhibit A are to the official real property records of the county or counties
(or parish or parishes) in which the mortgaged property is located and in which
records such documents are or in the past have been customarily recorded,
whether Deed Records, Oil and Gas Records, Oil and Gas Lease Records or other
records.

         4. A statement herein that a certain interest described herein is
subject to the terms of certain described or referred to agreements, instruments
or other matters shall not operate to subject such interest to any such
agreement, instrument or other matter except to the extent that such agreement,
instrument or matter is otherwise valid and presently subsisting nor shall such
statement be deemed to constitute a recognition by the parties hereto that any
such agreement, instrument or other matter is valid and presently subsisting.



                              Exhibit Q - Page 32
<PAGE>   85



                                   Schedule 1

              Schedule of Lenders' Commitments and Percentage Share

<TABLE>
<CAPTION>
                       Lenders                         Commitment                      Percentage Share
                       -------                         ----------                      ----------------    
<S>                                                  <C>                                   <C>       
NationsBank, N.A.                                    $  178,969,354.90                     13.255320%

CIBC Inc.                                            $  125,077,300.96                      9.263819%

Morgan Guaranty Trust Company of New York            $  178,969,354.95                     13.255320%

Chase Bank of Texas, National Association            $  120,332,991.31                      8.912433%

The Bank of New York                                 $   58,636,363.64                      4.342888%

The Bank of Nova Scotia                              $   96,590,840.62                      7.153976%

Royal Bank of Canada                                 $   96,590,840.62                      7.153976%

Union Bank of California, N.A.                       $   58,636,363.64                      4.342888%

Wells Fargo Bank, N.A.                               $   58,636,363.64                      4.342888%

Bank One, Texas, N.A.                                $   22,872,340.43                      1.694034%

Den Norske Bank ASA                                  $   39,090,909.09                      2.895258%

Paribas                                              $   39,090,909.09                      2.895258%

First Union National Bank                            $   53,323,837.94                      3.949417%

Bankers Trust Company                                $   19,545,454.55                      1.447629%

Credit Agricole Indosuez                             $   19,545,454.55                      1.447629%

Natexis Banque                                       $   19,545,454.55                      1.447629%

Toronto Dominion (Texas), Inc.                       $   52,755,621.88                      3.907332%

The Toyo Trust & Banking Co., Ltd.                   $   19,545,454.55                      1.447629%

Wachovia Bank, N.A.                                  $   33,778,383.40                      2.501788%

The Dai-Ichi Kangyo Bank, Ltd., New York             $   19,545,454.55                      1.447629%
Branch

The Sanwa Bank, Limited                              $   19,545,454.55                      1.447629%

Kredietbank N.V.                                     $   19,545,454.55                      1.447629%
                                                     ===============================================                      
Totals:                                              $1,350,169,957.96                    100.000000%

</TABLE>

                               Schedule 1 - Page 1

<PAGE>   86




                                   Schedule 3

                       Schedule of Restricted Subsidiaries

         This Schedule 3 is attached to and made a part of (i) that certain
Primary Credit Facility pursuant to that certain Second Amended and Restated
Credit Facility Agreement dated as of March 19, 1999 by and among Borrower,
NationsBank, N.A., as Administrative Agent, CIBC Inc., as Documentation Agent,
Morgan Guaranty Trust Company of New York, as Documentation Agent, Chase Bank of
Texas, National Association, as successor-in-interest to The Chase Manhattan
Bank, as Syndication Agent, the Co-Agents party thereto, and the Lenders from
time to time parties thereto, and (ii) that certain 364 Day Credit Facility
pursuant to that certain Second Amended and Restated Credit Facility Agreement
dated as of March 19, 1999 by and among Borrower, NationsBank, N.A., as
Administrative Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust
Company of New York, as Documentation Agent, Chase Bank of Texas, National
Association, as successor-in-interest to The Chase Manhattan Bank, as
Syndication Agent, the Co- Agents party thereto, and the Lenders from time to
time parties thereto.

Pioneer Natural Resources USA, Inc., a Delaware corporation
Pioneer International Resources Company, a Delaware corporation
Pioneer Resources Producing L.P., a Delaware limited partnership
Parker & Parsley (Canada) Petroleum Company, a Nova Scotia, Canada limited
liability company
Pioneer Resources, Inc., , a Delaware corporation
P&PCanada LP Co., a Delaware corporation
Pioneer Natural Resources Canada, Inc., an Alberta,
Canada limited liability company Pioneer Natural Resources (Argentina) S.A., an
Argentina limited liability company
Pioneer Natural Resources (Tierra del Fuego)S.A., an Argentina limited
liability company
Westpan NGL Co., a Delaware corporation
Pioneer Natural Resources (Cayman) Ltd., a Cayman exempted company
Parker & Parsley Petroleum Australia Holdings Pty Limited (A.C.N. 064 589 242),
 a New South Wales, Australia corporation
Parker & Parsley Petroleum Australia Pty Limited (A.C.N. 064 589 180), a New 
 South Wales, Australia corporation
Bridge Oil (U.S.A.) Inc., a Delaware corporation

 

                               Schedule 3 - Page 1

<PAGE>   87




                                   Schedule 4

                              Schedule of Insurance

















                               Schedule 4 - Page 1

<PAGE>   88



                                   Schedule 5

                        Schedule of Security Instruments

Guaranties   -    Pioneer Natural Resources USA, Inc., a Delaware corporation
                  Pioneer International Resources Company, a Delaware 
                  corporation
                  Pioneer Resources Producing L.P., a Delaware limited 
                  partnership
                  Pioneer Resources, Inc., a Delaware corporation
                  P&PCanada LP Co., a Delaware corporation
                  Pioneer Natural Resources Canada Inc., an Alberta, Canada 
                  corporation
                  Westpan NGL Co., a Delaware corporation
                  Pioneer Natural Resources (Argentina) S.A., an Argentina 
                  limited liability company
                  Pioneer Natural Resources (Tierra del Fuego) S.A., an 
                  Argentina limited liability company

Pledge Agreements or Deeds of Mortgage, Blank Stock Powers and Financing
Statements:

         Pledge Agreement by Pioneer Resources, Inc., a Delaware corporation,
         covering shares of Parker & Parsley (Canada) Petroleum Company, a Nova
         Scotia, Canada limited liability company

         Pledge Agreement by P&PCanada LP Co., a Delaware corporation, covering
         shares of Parker & Parsley (Canada) Petroleum Company, a Nova Scotia,
         Canada limited liability company

         Deed of Mortgage by Pioneer Natural Resources Company USA, Inc., a
         Delaware corporation, covering shares of Parker & Parsley Petroleum
         Australia Holdings Pty. Limited (A.C.N. 064 589 242), a New South
         Wales, Australia corporation

         Pledge Agreement by Pioneer International Resources Company, a Delaware
         corporation, covering shares of Pioneer Natural Resources Canada Inc.,
         an Alberta, Canada limited liability company

         Pledge Agreement by Pioneer Natural Resources USA, Inc., a Delaware
         corporation, covering shares of Pioneer Natural Resources (Cayman)
         Ltd., a Cayman exempted company




                              Schedule 5 - Page 1

<PAGE>   1
                                                                   EXHIBIT 10.70

                            [364 DAY CREDIT FACILITY]

===============================================================================

              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

                                  by and among

                       PIONEER NATURAL RESOURCES COMPANY,
                                  as BORROWER,

                                       and

                               NATIONSBANK, N.A.,
                            as ADMINISTRATIVE AGENT,

                                       and

                                   CIBC INC.,
                             as DOCUMENTATION AGENT,

                                       and

                   MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                             as DOCUMENTATION AGENT,

                                       and

                   CHASE BANK OF TEXAS, NATIONAL ASSOCIATION,
                              as SYNDICATION AGENT,

                         THE CO-AGENTS SIGNATORY HERETO,

                                       and

                       THE OTHER LENDERS SIGNATORY HERETO

                           Dated as of March 19, 1999

                              ---------------------

                     NATIONSBANC MONTGOMERY SECURITIES LLC,
                        as LEAD ARRANGER and BOOK MANAGER



===============================================================================



<PAGE>   2


              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

         THIS SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT (herein
called this "Amendment and Restatement"), is made as of March 19, 1999, by and
among PIONEER NATURAL RESOURCES COMPANY, a Delaware corporation (the
"Borrower"), NATIONSBANK, N.A., as successor-by-merger to NationsBank of Texas,
N.A., as Administrative Agent and Collateral Agent, CIBC INC., as Documentation
Agent, MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation Agent, CHASE
BANK OF TEXAS, NATIONAL ASSOCIATION, as successor-in-interest to The Chase
Manhattan Bank, as Syndication Agent, the "Co-Agents" party to the Credit
Agreement (as herein defined), and the other Lenders from time to time parties
to the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents have heretofore entered into a certain Amended and
Restated Credit Facility Agreement - 364- Day Credit Facility, dated as of
December 18, 1997, as previously amended (herein the "Credit Agreement"); and

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co-Agents now intend to amend and restate the Credit Agreement;

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, each of the Borrower, the Lenders, the Managing
Agents, the Collateral Agent and the Co-Agents hereby agree as follows:

         SECTION 1. Defined Terms. All capitalized terms used but not otherwise
defined herein shall have the meanings given in the Credit Agreement, as amended
and restated by the Amendment and Restatement.

         SECTION 2. Amendments to Credit Agreement. Effective as of Effective
Date, the Credit Agreement is hereby amended and restated in its current form
with the following amendments:

                  a. The definitions of "Amendment Fee Rate", "Applicable Rating
         Level", "Consolidated Interest Expense", "EBITDAX", "Eurodollar Margin"
         and "Facility Fee Rate" in Section 1.1 of the Credit Agreement are
         hereby amended and restated to read in their entirety as follows:

                  " "Amendment Fee Rate" means 37.5 basis points."

                  " "Applicable Rating Level" means the level set forth below
         that corresponds to the lowest of ratings issued from time to time by
         Moody's and S&P, as applicable to Borrower's senior, unsecured
         long-term debt:




<PAGE>   3



<TABLE>
<CAPTION>
=========================================================
                              Moody's        S&P
- ---------------------------------------------------------
<S>                          <C>          <C>
Level I                       >= Baa3      >= BBB-
- ---------------------------------------------------------
Level II                         Ba1          BB+
- ---------------------------------------------------------
Level III                        Ba2          BB
- ---------------------------------------------------------
Level IV                      <= Ba3       <= BB-
=========================================================
</TABLE>

         For example, if the Moody's rating is Ba1 and the S&P rating is BB,
         Level III shall apply.

                  For purposes of the foregoing, (i) ">=" means a rating more
         favorable than or equal to; "<=" means a rating less favorable than or
         equal to; (ii) if ratings for Borrower's senior unsecured long-term
         debt shall not be available from S&P or Moody's, Level IV shall be
         deemed applicable; (iii) if any of the Rating Agencies shall change its
         ratings nomenclature prior to the date all Obligations have been paid
         and the Commitments canceled, Borrower and the Lenders shall negotiate
         in good faith to amend the references to specific ratings in this
         definition to reflect such change, and pending such amendment, if an
         appropriate Applicable Rating Level is otherwise not determinable based
         upon the foregoing grid, the last Applicable Rating Level in effect at
         the time of such change shall continue to apply."

                  " "Consolidated Interest Expense" means, for any period, total
         interest expense, whether paid or accrued, of Borrower and its
         Subsidiaries on a Consolidated basis, including, without limitation,
         all commissions, discounts and other fees and charges owed with respect
         to Letters of Credit (as defined in the Primary Credit Facility)."

                  " "EBITDAX" means, for any period the sum of the amounts for
         such period of Consolidated net income (excluding gains and losses on
         the sale of assets), Consolidated Interest Expense, depreciation
         expense, depletion expense, amortization expense, federal and state
         income taxes, exploration and abandonment expense and other non-cash
         charges and expenses, all as determined on a Consolidated basis for
         Borrower and its Subsidiaries.

                  " "Eurodollar Margin" means, on any date, with respect to each
         Eurodollar Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the number of basis points per annum set
         forth below based on the Applicable Rating Level:


               <TABLE>                                             
               <CAPTION>                                           
               ==================================================  
                      Applicable                                   
                     Rating Level                                  
                     ------------                                  
               --------------------------------------------------  
               <S>                                <C>              
                        Level I                    150.0 b.p.      
               --------------------------------------------------  
                        Level II                   200.0 b.p.      
               --------------------------------------------------  
                        Level III                  225.0 b.p.      
               --------------------------------------------------  
                        Level IV                   250.0 b.p.      
               ==================================================  
               </TABLE>                                            



                                        2

<PAGE>   4
         Changes in the Eurodollar Margin will occur automatically without prior
         notice upon the effectiveness of any change of the Applicable Rating
         Level. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Eurodollar Margin."

         "       "Facility Fee Rate" means, on any date that a facility fee
         is due pursuant to Section 2.7, the number of basis points per annum
         set forth below based on the Applicable Rating Level on such date;
         provided, that notwithstanding the provisions of Section 2.7, the
         facility fee payable to each Lender at the Facility Fee Rate pursuant
         to Section 2.7 for any period shall be payable on the average daily
         unused amount (which amount shall include any outstanding Swing Line
         Advances or Competitive Bid Advances) of such Lender's Percentage Share
         of the Facility Amount for such period:

<TABLE>
<CAPTION>
==========================================================
         Applicable                 Facility Fee Rate
        Rating Level                     Margin
- ----------------------------------------------------------
<S>                                 <C>      
         Level I                        37.5 b.p.
- ----------------------------------------------------------
         Level II                       50.0 b.p.
- ----------------------------------------------------------
         Level III                      50.0 b.p.
- ----------------------------------------------------------
         Level IV                       50.0 b.p.
==========================================================
</TABLE>

         Changes in the Facility Fee Rate will occur automatically without prior
         notice. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Facility Fee Rate."

         b.                Section 1.1 of the Credit Agreement is hereby
                  amended by inserting the following definitions of "Base Rate
                  Margin", "Consolidated Tangible Net Worth", " Debt Issuance",
                  "Engineering Report", "Initial Engineering Report", "Net Cash
                  Proceeds", "Non-Recourse Debt", "Properties", "Properties
                  NPV", "Properties NPV to Total Debt Ratio", "Public Notes",
                  "Qualified Investments", "Security Documents", "Senior Debt",
                  "Senior Debt Margin", "Senior Leverage Ratio", "Subordinated
                  Debt" and "Total Leverage Ratio" in appropriate alphabetical
                  order:

         "        "Base Rate Margin" means, on any date, with respect to each
         Base Rate Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the greater of (A) the Eurodollar Margin
         less 125 basis points or (B) zero."

         "       "Consolidated Tangible Net Worth" means (i) the Consolidated
         shareholder's equity of Borrower and its Subsidiaries (determined in
         accordance with GAAP), less (ii) the amount of Consolidated intangible
         assets of Borrower and its Subsidiaries, plus (iii) the aggregate
         amount of any non-cash write downs under Financial Accounting Standards
         19, 109 and 121, on a consolidated basis, by Borrower and its
         Subsidiaries after December 31, 1998."

 

                                        3

<PAGE>   5




                  " "Debt Issuance" means the sale or issuance after February 1,
         1999, by Borrower or any Restricted Person of notes or other debt
         securities for cash pursuant to a registration statement under the
         Securities Act of 1933, as amended (the "Act"), or to qualified
         institutional buyers in reliance on Rule 144A under the Act or pursuant
         to a transaction effected as private placement pursuant to an exemption
         to registration under the Act."

                  " "Engineering Report" means the Initial Engineering Report."

                  " "Initial Engineering Report" means that certain engineering
         report, delivered to the Administrative Agent on February 26, 1999
         concerning the Properties."

                  " "Net Cash Proceeds" means the cash or cash equivalent
         proceeds received by the Borrower or any Restricted Person as a result
         of (i) an issuance of common stock, preferred stock or other equity of
         the Borrower or any Restricted Person, (ii) a Debt Issuance, or (iii) a
         sale of Property of Borrower or any Restricted Person, in each case
         after deducting all of the following, as applicable, (a) legal fees
         paid or reimbursed by Borrower or any Restricted Person and allocable
         to such transaction, (b) underwriters' discounts, initial purchasers'
         discounts, placement agent's fees, brokers' commissions and other
         discounts, commissions or fees incurred in connection with such
         transaction, to the extent paid or reimbursed by Borrower or any
         Restricted Person, (c) registration fees, printer's fees and other
         costs of sale paid or reimbursed by Borrower or any Restricted Person
         in connection with such transaction, and (d) any reserves maintained by
         Borrower or any Restricted Person for any closing cost adjustments or
         similar contingencies in connection with such transaction. Proceeds of
         any such transaction consisting of notes, stock, securities or other
         non-cash assets or property shall not be included as Net Cash Proceeds;
         provided, however, any cash or cash equivalents received as a result of
         the sale, pledge or transfer of any such note, stock, securities or
         other non-cash assets or property or as a payment on account of or
         otherwise realized on account of principal or capital of any note,
         stock, securities or other non-cash assets or property (but not
         dividends, interest or operating income in respect of any assets or
         property) shall be treated as cash or cash equivalent proceeds received
         by Borrower or a Restricted Person at the time such cash or cash
         equivalent is received by Borrower or any Restricted Person."

                  " "Properties" means, at the particular time in question, all
         material oil and gas properties and reserves (which properties and
         reserves shall be free of any Liens other than Permitted Liens) of the
         Borrower and the Subsidiaries at such time and that were evaluated in
         the Initial Engineering Report or, if applicable, the Engineering
         Report and other information most recently provided by Borrower
         pursuant to Section 5.1(b)(4)."

                  " "Properties NPV" means, at the particular time in question,
         the net present value of the Borrower's and the Subsidiaries' proved
         reserves included in the Properties set forth in the Engineering
         Report."

                  " "Properties NPV to Total Debt Ratio" means at any time the
         ratio of (a) the Properties NPV to (b) Borrower's Total Debt."


 

                                        4

<PAGE>   6



                  " "Public Notes" means each of the following: (i) Borrower's
         $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's $150,000,000
         8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
         Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes
         due 2028, together with all guaranties thereof and all notes issued
         from time to time in replacement therefor and (v) any other publicly
         tradeable notes, bonds or debentures outstanding as of February 1,
         1999, which notes, bonds or debentures by their terms require that they
         be secured equally and ratably with any collateral under this
         Agreement."

                  " "Qualified Investments" means (i) the purchase by Borrower
         or one of its Subsidiaries of Properties constituting proved reserves,
         or (ii) capital expenditures made by Borrower or one of its
         Subsidiaries to maintain, enhance or develop Properties constituting
         proved reserves owned by Borrower or one of its Subsidiaries."

                  " "Security Documents" means, collectively, the Mortgage, Deed
         of Trust, Assignment, Security Agreement and Financing Statement from
         the Borrower or any of its Subsidiaries as the case may be, granted to
         a Collateral Agent selected by the Administrative Agent and reasonably
         acceptable to Borrower to secure equally and ratably the Obligations
         and the Public Notes, substantially in the form attached hereto as
         Exhibit R with appropriate insertions (with any modifications necessary
         to comply with applicable state laws or filing requirements), and any
         and all further documents, financing statements, agreements and
         instruments which may be required under applicable law, or which the
         Agent may reasonably request, in order to satisfy the requirements of
         Section 5.1(n)."

                  " "Senior Debt" means Total Funded Debt of the Borrower and
         its Subsidiaries, other than Total Funded Debt that is Subordinated
         Debt."

                  " "Senior Debt Margin" means 25 basis points per annum.

                  " "Senior Leverage Ratio" means at any time the ratio of (a)
         Borrower's then Consolidated Senior Debt to (b) Borrower's EBITDAX;
         provided that for purposes of the foregoing calculation, EBITDAX for
         any Fiscal Quarter shall be deemed to be four times the EBITDAX for
         such Fiscal Quarter."

                  " "Subordinated Debt" means all unsecured Debt of the Borrower
         for money borrowed which is subordinated in right of payment to the
         payment of all Obligations, upon customary terms satisfactory to the
         Administrative Agent."

                  " "Total Leverage Ratio" means at any time the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX; provided that for purposes of the foregoing calculation,
         EBITDAX for any Fiscal Quarter shall be deemed to be four times the
         EBITDAX for such Fiscal Quarter."


 

                                        5

<PAGE>   7




         c.                Section 1.1 of the Credit Agreement is hereby
                  amended by deleting the following definitions of "Commitment
                  Utilization", "Commitment Utilization Level" and "Commitment
                  Utilization Margin" in their entirety.

         d.                The definition of "Debt" in Section 1.1 of the
                  Credit Agreement is hereby amended by adding the following to
                  the end of clause (h) before the semicolon: "and the amount of
                  deferred revenue attributable to any forward sale of
                  production or Properties for which such Person has directly or
                  indirectly received payment in advance."

         e.                Section 4.1(h) of the Credit Agreement is hereby
                  amended by inserting at the end of Section 4.1(h) the
                  following sentence:

         "There are no statements or conclusions in the Engineering Report which
         are based upon or include misleading information or fail to take into
         account material information regarding the matters reported therein, it
         being understood that (1) the Engineering Report is necessarily based
         upon professional opinions, estimates and projections and (2) Borrower
         does not warrant that such opinions, estimates and projections will
         ultimately prove to have been accurate."

         f.                Section 5.1 of the Credit Agreement is hereby
                  amended by inserting the following Section 5.1(n) after
                  Section 5.1(m) of the Credit Agreement:

         "        (n)      Springing Lien. In the event that any Event of
                  Default has occurred and is continuing without affecting in
                  any way any other rights of the Lenders hereunder, the
                  Administrative Agent, at the direction of the Required
                  Lenders, may request that the Borrower, and the Borrower
                  agrees to:

                           (i) duly execute and deliver to the Administrative
                  Agent (or such other Person designated by the Administrative
                  Agent) the Security Documents and cause each such Security
                  Document to be filed, registered and recorded, as the law may
                  require or the Administrative Agent may request, in each
                  jurisdiction where so required or requested, and deliver to
                  the Administrative Agent an acknowledgment copy, or other
                  evidence satisfactory to it, of each such filing, registration
                  and recordation, in order to mortgage, assign, grant a
                  security interest in and pledge to the Administrative Agent
                  (or such other Person designated by the Administrative Agent),
                  acting on behalf of the Lenders, all of the Borrower's and the
                  Restricted Subsidiaries' right, title and interest in and to
                  the Properties located in the United States, and the proceeds
                  thereof, having a Properties NPV, as of the date of the
                  Engineering Report, of 80% of the aggregate Properties NPV
                  attributable to Properties located in the United States (the
                  "Collateral") in such request, and to perfect and evidence the
                  first priority of all such Security Documents (subject to
                  liens and encumbrances permitted by the terms of such
                  instruments); provided that the Borrower shall not, and shall
                  not permit any of its Subsidiaries to, on or after the
                  Effective Date enter into any amendment of any such contract
                  or agreement, or enter into any other contract or agreement,
                  that in either case would result in any additional such
                  material consent, authorization or approval requirement; and

 

                                        6

<PAGE>   8


                           (ii) deliver to the Administrative Agent, within 30
                  days of such request for delivery of the Security Documents
                  (or, if a Person other than the Administrative Agent is to act
                  as collateral agent under the Security Documents, if later,
                  within fifteen (15) days of the designation and acceptance by
                  such Person of the collateral agency), evidence acceptable to
                  the Administrative Agent, in its reasonable discretion,
                  indicating that Security Documents covering 80% of the
                  Properties NPV attributable to the Properties located in the
                  United States have been executed, acknowledged, filed,
                  registered and recorded, as the law may require or the Agent
                  may request, in each jurisdiction where so required or
                  requested.

         Borrower further agrees to execute, or cause its Subsidiaries to
         execute, any and all further documents, financing statements,
         agreements and instruments, and take all further actions (including
         filing Uniform Commercial Code financing statements), which may be
         required under applicable law, or which the Administrative Agent may
         reasonably request, in order to effectuate the transactions
         contemplated by this Section 5.1(n) and in order to grant, preserve,
         protect and perfect the validity and first priority of any security
         interests created pursuant to the Security Documents. Borrower will
         also provide and cause its Subsidiaries to provide at their own expense
         to the Administrative Agent such title records or opinions as may be in
         the files of Borrower or its Subsidiaries and operating agreements and
         other instruments and documents relating to the Properties covered by
         the Security Documents then in the possession of the Borrower or any
         Subsidiary as the Administrative Agent may reasonably request. At such
         time as no Event of Default is continuing upon request by Borrower to
         Administrative Agent, Administrative Agent shall advise the Collateral
         Agent, pursuant to the terms of the Security Documents, to terminate
         all Security Documents and release all Liens created thereby."

         g.               Subsection 5.2(a)(5) of the Credit Agreement is
                  hereby amended and restated to read in its entirety as
                  follows:

         "        (5)      Debt, other than Debt otherwise permitted by another
                           subparagraph of this Section 5.2(a), which, at the
                           time incurred, is (i) at prevailing market rates of
                           interest and contains covenants and conditions and
                           events of default no more onerous to Designated
                           Entities than the terms of this Agreement; provided,
                           that no Default or Event of Default either (A) exists
                           at the time of the issuance of such Debt and (B) will
                           result from, and be continuing after, the incurrence
                           of such Debt; provided further, that such Debt shall
                           have a final maturity after August 7, 2002 and be on
                           terms and conditions reasonably acceptable to the
                           Administrative Agent."

         h.                Section 5.2(e) of the Credit Agreement is amended
                  and restated to read in its entirety as follows:

 

                                        7

<PAGE>   9


         "       (e)       Limitation on Dividends and Other Restricted
                           Payments. The Borrower will not and will not permit
                           any of its Subsidiaries to pay or declare dividends
                           (other than stock dividends) on, or repurchase, the
                           Borrower's capital stock in excess of $10,000,000 in
                           the aggregate for all such payments and purchases in
                           any Fiscal Year. Borrower will not, and will not
                           permit any Restricted Subsidiary to, make any other
                           Restricted Payments in excess of $5,000,000 in the
                           aggregate for all such Restricted Payments during any
                           Fiscal Year; provided, however, that in the event
                           that any Unrestricted Subsidiary of Borrower is
                           redesignated to be a Restricted Subsidiary of
                           Borrower for purposes of this Agreement, then for
                           purposes of redetermining compliance with this
                           Section, all Restricted Payments made to such
                           Unrestricted Subsidiary shall be deducted from the
                           aggregate total of all Restricted payments made
                           during such Fiscal Year. No Restricted Payment may be
                           made (1) if the Obligations shall exceed the Facility
                           Amount, (2) if any Default or Event of Default shall
                           have occurred and be continuing, or (3) if as a
                           result thereof, any Default or Event of Default shall
                           occur and be continuing."

                           i. Subsection 5.2 of the Credit Agreement is amended
                  by adding the following Section 5.2(l).

         "       (l)       "The Borrower will not, and will not permit any of
                           its Subsidiaries to, sell, transfer, assign or
                           otherwise convey any Property (other than to the
                           Borrower or one of its Subsidiaries) to the extent
                           the aggregate value of non-cash consideration for all
                           sales, transfers, assignments and other conveyances
                           of any Property (other than to the Borrower or one of
                           its Subsidiaries) received on and after February 1,
                           1999 has exceeded or would exceed $25,000,000 in the
                           aggregate. As used herein, the term "non-cash
                           consideration" means any consideration given by or on
                           behalf of the purchaser of Property other than cash,
                           any cash equivalent or any other asset to the extent
                           that at the time in question such other asset has
                           been converted (by collection, sale or otherwise)
                           into cash or any cash equivalent. The value of any
                           such non-cash consideration shall be its fair market
                           value at the time that the contract for such sale,
                           transfer, assignment or other conveyance is entered
                           into, which fair market value shall be determined (i)
                           by reference to market quotations in the case of
                           publicly traded securities or other consideration of
                           the type which is subject to market quotations, (ii)
                           if clause (i) is not applicable, by the value for
                           such consideration set forth in such contract by the
                           parties or (iii) if neither (i) or (ii) is
                           applicable, by a resolution of the board of directors
                           of the Borrower.

                           j. Section 5.3(a) of the Credit Agreement is hereby
                  amended and restated to read in its entirety as follows:

 

                                        8

<PAGE>   10




"        (a)     Senior Leverage Ratio. Borrower's Consolidated Senior
Leverage Ratio will not (i) as of last day of any Fiscal Quarter be greater than
5.75 to 1.0."

k.               Section 5.3(b) of the Credit Agreement is hereby amended
         and restated to read in its entirety as follows:

"        (b)     Total Leverage Ratio. Borrower's Consolidated Total
Leverage Ratio will not as of the last day of any Fiscal Quarter be greater than
5.75 to 1.00."

l.               Section 5.3 of the Credit Agreement is hereby amended by
         inserting after Section 5.3(b) of the Credit Agreement the following
         Sections 5.3(c) and 5.3(d):

"        (c)     Minimum Consolidated Tangible Net Worth. Borrower will
not permit its Consolidated Tangible Net Worth as of the end of any Fiscal
Quarter, commencing with the Fiscal Quarter ending March 31, 1999, to be less
than (i) $600,000,000 plus (ii) an amount equal to 50% of the sum of Borrower's
and its Subsidiaries' Consolidated net income for each Fiscal Quarter, beginning
with the Fiscal Quarter ending March 31, 1999, during which such Consolidated
net income is greater than $0 plus (iii) an amount equal to 85% of the net cash
proceeds received by the Borrower and its Subsidiaries from the issuance of any
common stock, preferred stock or other equity for each Fiscal Quarter, beginning
with the Fiscal Quarter ending March 31, 1999.

         (d)     Properties NPV to Total Debt Ratio. Borrower's Properties
NPV to Total Debt Ratio will not as of the end of any Fiscal Quarter ending
either June 30th or December 31st, commencing with the Fiscal Quarter ending
December 31, 1998, be less than 1.25 to 1.00."

m.               The Credit Agreement is hereby amended by replacing Exhibit
         I to the Credit Agreement with Exhibit I to this Amendment and
         Restatement.

n.               The Credit Agreement is hereby amended by replacing Exhibit
         J to the Credit Agreement with Exhibit J to this Amendment and
         Restatement.

o.               The Credit Agreement is hereby amended by inserting Exhibit
         R to this Amendment and Restatement as Exhibit R to the Credit
         Agreement following Exhibit Q to the Credit Agreement.

p.               The Credit Agreement is hereby amended by replacing
         Schedule 1 to the Credit Agreement with Schedule 1 to this Amendment
         and Restatement.

q.               The Credit Agreement is hereby amended by replacing
         Schedule 3 to the Credit Agreement with Schedule 3 to this Amendment
         and Restatement.


 

                                        9

<PAGE>   11
r.               The Credit Agreement is hereby amended by replacing
         Schedule 4 to the Credit Agreement with Schedule 4 to this Amendment
         and Restatement.

s.               Schedule 5 to the Credit Agreement is hereby amended by
         replacing Schedule 5 to the Credit Agreement with Schedule 5 to this
         Amendment and Restatement.

         SECTION 4. Representations and Warranties. To confirm each Lender's
understanding concerning Borrower and its businesses, properties and
obligations, and to induce the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender to enter into this Amendment and Restatement, the
Borrower hereby reaffirms to the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender that, as of the date hereof, its representations and
warranties contained in Section 4.1 of the Credit Agreement (as amended by this
Amendment and Restatement) and in the other Loan Documents to which it is a
party (except to the extent such representations and warranties relate solely to
an earlier date) are true and correct and additionally represents and warrants
as follows:

         A.       The execution and delivery of this Amendment and Restatement
                  and the performance by the Borrower and the Restricted
                  Subsidiaries of their respective obligations under this
                  Amendment and Restatement, the Credit Agreement and the other
                  Loan Documents, as amended hereby, are within the Borrower's
                  or such Restricted Subsidiaries' corporate or partnership
                  powers, have been duly authorized by all necessary corporate
                  or partnership action, have received all necessary
                  governmental approval (if any shall be required), and do not
                  and will not contravene or conflict with any provision of law
                  or of the Borrower's or such Restricted Subsidiaries' charter
                  or bylaws or partnership agreement or of any contractual
                  restriction, law or governmental regulation or court decree or
                  order binding on or affecting the Borrower or such Restricted
                  Subsidiary.

         B.       This Amendment and Restatement and the Credit Agreement as
                  amended hereby are, and the other Loan Documents when duly
                  executed and delivered will be, legal, valid and binding
                  obligations of the Borrower and each Restricted Subsidiary
                  which is a party hereto or thereto, enforceable in accordance
                  with their terms except as such enforcement may be limited by
                  bankruptcy, insolvency or similar laws of general application
                  relating to the enforcement of creditors' rights generally and
                  by general principles of equity.

         SECTION 5. Conditions to Effectiveness. The effectiveness of this
Amendment and Restatement is conditioned upon receipt by the Administrative
Agent of all the following documents and items, each in form and substance
reasonably satisfactory to the Administrative Agent:

         A.       this Amendment and Restatement executed by the Borrower and
                  the Required Lenders.

         B.       Delivery of the Initial Engineering Report.

         C.       Payment to Administrative Agent for the account of each Lender
                  which executes and delivers a copy of this Amendment and
                  Restatement to the Administrative Agent on or before March 19,
                  1999, of a non-refundable amendment fee payable to each such
                  Lender determined by applying the Amendment Fee Rate to such
                  Lender's Percentage Share of the Facility Amount as of the
                  date of this Amendment and Restatement.

 

                                       10

<PAGE>   12



         D.       Payment to Administrative Agent for the account of NationsBanc
                  Montgomery Securities LLC, as sole arranger and book manager,
                  a non-refundable advisory fee in the amount set forth in that
                  certain Commitment/Fee Letter, dated February 4, 1999 between
                  NationsBanc Montgomery Securities LLC and the Borrower.

         E.       Delivery of favorable opinions of counsel for Borrower and the
                  Restricted Subsidiaries, in form and substance acceptable to
                  the Administrative Agent, in its sole discretion.

         F.       Unless the Canadian Credit Facility shall have terminated, the
                  Required Lenders (as defined in the Canadian Credit Facility)
                  shall have consented to this Amendment, it being agreed by the
                  parties hereto that such consent may require reductions in
                  commitments and paydowns under the Canadian Credit Facility
                  similar to the reductions and paydowns required by Sections
                  2.9(d), (e) and (f) of the Primary Credit Facility and to the
                  extent permitted by Section 2.9(j) of the Primary Credit
                  Facility.

         H.       Such other documents or items that the Administrative Agent
                  may reasonably request.

         SECTION 6. Reaffirmation of Credit Agreement. This Amendment and
Restatement constitutes a "Loan Document" as defined in the Credit Agreement and
shall be deemed to be an amendment and restatement of the Credit Agreement, and
the Credit Agreement, as amended and restated hereby, is hereby ratified,
approved and confirmed in each and every respect. All references to the Credit
Agreement or the Credit Facility Agreement in any other document, instrument,
agreement or writing shall hereafter be deemed to refer to this Amendment and
Restatement.

         SECTION 7. Parties in Interest. All grants, covenants and agreements
contained in this Amendment and Restatement shall bind and inure to the benefit
of the parties thereto and their respective successors and assigns; provided,
however, that no Restricted Subsidiary may assign or transfer any of its rights
or delegate any of its duties or obligations under this Amendment and
Restatement or any Loan Document without the prior written consent of all
Lenders.

         SECTION 8. Counterparts. This Amendment and Restatement may be
separately executed in any number of counterparts and by different parties
hereto in separate counterparts, each of which when so executed shall be deemed
to constitute one and the same Amendment and Restatement.

         SECTION 9. GOVERNING LAW. THIS AMENDMENT AND RESTATEMENT AND THE OTHER
LOAN DOCUMENTS SHALL BE DEEMED CONTRACTS AND INSTRUMENTS MADE UNDER THE LAWS OF
THE STATE OF TEXAS AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF THE STATE OF TEXAS AND THE LAWS OF THE UNITED STATES OF
AMERICA, WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW. CHAPTER 15 OF TEXAS
REVISED CIVIL STATUTES ANNOTATED ARTICLE 5069 (WHICH REGULATES CERTAIN REVOLVING
CREDIT LOAN ACCOUNTS AND REVOLVING TRI-PARTY ACCOUNTS) DOES NOT APPLY TO THIS
AMENDMENT AND RESTATEMENT OR TO THE NOTES.

 

                                       11

<PAGE>   13




         SECTION 10. Severability. If any term or provision of this Amendment
and Restatement or of any Loan Document shall be determined to be illegal or
unenforceable in any jurisdiction, such term or provision shall, as to such
jurisdiction, be illegal or unenforceable, without affecting the remaining terms
or provisions in that jurisdiction or the legality or enforceability of such
terms or provisions in any other jurisdiction.

         SECTION 11. WAIVER OF JURY TRIAL, PUNITIVE DAMAGES. EACH OF THE
BORROWER, AGENTS AND LENDERS HEREBY (I) IRREVOCABLY WAIVES, TO THE MAXIMUM
EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY LITIGATION, DIRECTLY OR INDIRECTLY, AT ANY TIME ARISING OUT OF,
UNDER OR IN CONNECTION WITH THE LOAN DOCUMENTS OR ANY TRANSACTION CONTEMPLATED
THEREBY OR ASSOCIATED THEREWITH, BEFORE OR AFTER MATURITY; (II) IRREVOCABLY
WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO
CLAIM OR RECOVER IN ANY SUCH LITIGATION ANY EXEMPLARY, PUNITIVE OR CONSEQUENTIAL
DAMAGES; (III) CERTIFIES THAT NO PARTY HERETO NOR ANY REPRESENTATIVE OR AGENT OR
COUNSEL FOR ANY PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, OR IMPLIED
THAT SUCH PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE
FOREGOING WAIVERS; AND (IV) ACKNOWLEDGES THAT IT HAS BEEN INDUCED TO ENTER INTO
THIS AMENDMENT AND RESTATEMENT, THE OTHER LOAN DOCUMENTS AND THE TRANSACTIONS
CONTEMPLATED HEREBY AND THEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS CONTAINED IN THIS SECTION.

         SECTION 12. FORUM SELECTION AND CONSENT TO JURISDICTION. ANY LITIGATION
BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AMENDMENT
AND RESTATEMENT OR ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF
DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENTS, THE
LENDERS OR THE BORROWER SHALL BE BROUGHT AND MAINTAINED EXCLUSIVELY IN THE
COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE
NORTHERN DISTRICT OF TEXAS; PROVIDED, HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT
AGAINST ANY COLLATERAL OR OTHER PROPERTY MAY BE BROUGHT, AT THE COLLATERAL
AGENT'S OPTION, IN THE COURTS OF ANY JURISDICTION WHERE SUCH COLLATERAL OR OTHER
PROPERTY MAY BE FOUND. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE
JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND THE UNITED STATES DISTRICT
COURT FOR THE NORTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION
AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED
THEREBY IN CONNECTION WITH SUCH LITIGATION. BORROWER FURTHER IRREVOCABLY
CONSENTS TO THE SERVICE
 

                                       12

<PAGE>   14


OF PROCESS BY REGISTERED MAIL, POSTAGE PREPAID, OR BY PERSONAL SERVICE WITHIN OR
WITHOUT THE STATE OF TEXAS. FOR THE PURPOSE OF ANY ACTION OR PROCEEDING
INSTITUTED IN THE FEDERAL OR STATE COURTS OF TEXAS, EACH RESTRICTED SUBSIDIARY
OF THE BORROWER HEREBY IRREVOCABLY DESIGNATES BORROWER WITH OFFICES ON THE DATE
HEREOF AT 1400 WILLIAMS SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD, IRVING,
TEXAS 75039 TO RECEIVE FOR AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY, SERVICE
OF PROCESS IN TEXAS. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE
FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER
MAY HAVE TO THE LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT
REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN
INCONVENIENT FORUM. TO THE EXTENT THAT THE BORROWER HAS OR HEREAFTER MAY ACQUIRE
ANY IMMUNITY FROM JURISDICTION OF ANY COURT OR FROM ANY LEGAL PROCESS (WHETHER
THROUGH SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT, ATTACHMENT IN AID OF
EXECUTION OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS PROPERTY, BORROWER HEREBY
IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS OBLIGATIONS UNDER THIS
AMENDMENT AND RESTATEMENT AND THE OTHER LOAN DOCUMENTS.

         SECTION 13. Effectiveness. This Amendment and Restatement shall become
effective as of March 19, 1999 ("Effective Date"), when counterparts hereof
executed on behalf of the Borrower and the Required Lenders (or notice thereof
satisfactory to the Agent) shall have been received by the Administrative Agent,
and all conditions set forth in Section 4 hereof have been fulfilled.

         SECTION 14. Entire Agreement. THIS WRITTEN AMENDMENT AND RESTATEMENT
AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT
ORAL AGREEMENTS OF THE PARTIES.

           THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                    [SIGNATURES BEGIN ON THE FOLLOWING PAGE]


 

                                       13

<PAGE>   15



         IN WITNESS WHEREOF, this Amendment and Restatement is executed as of
the date first written above.


                              BORROWER:

                              PIONEER NATURAL RESOURCES
                              COMPANY

                              By:
                                 ---------------------------------------------
                              Name:    M. Garrett Smith
                              Title:   Executive Vice President and Chief
                                       Financial Officer






 

                                       S-1

<PAGE>   16



                              LENDERS:

                              NATIONSBANK, N.A., successor-by-merger
                              to NationsBank of Texas, N.A., individually
                              and as Administrative Agent and as Collateral
                              Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 


                                       S-2

<PAGE>   17




                              CIBC INC., individually and as
                              Documentation Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 


                                       S-3

<PAGE>   18




                              MORGAN GUARANTY TRUST
                              COMPANY OF NEW YORK, individually
                              and as Documentation Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 







                                       S-4

<PAGE>   19




                              CHASE BANK OF TEXAS, NATIONAL
                              ASSOCIATION, as successor-in-interest to
                              The Chase Manhattan Bank, individually and
                              as Syndication Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 


                                       S-5

<PAGE>   20



                   [SIGNATURE PAGE S-6 INTENTIONALLY OMITTED]





 

                                       S-6

<PAGE>   21




                              THE BANK OF NEW YORK, individually
                              and as Co-Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:




 

                                       S-7

<PAGE>   22




                              THE BANK OF NOVA SCOTIA,
                              individually and as Co-Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:




 

                                       S-8

<PAGE>   23



                              ROYAL BANK OF CANADA, individually
                              and as Co-Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                       S-9

<PAGE>   24



                              UNION BANK OF CALIFORNIA, N.A.,
                              individually and as Co-Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 


                                      S-10

<PAGE>   25



                              WELLS FARGO BANK, N.A.,
                              individually and as Co-Agent

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 



                                      S-11

<PAGE>   26



                              BANK ONE, TEXAS, N.A., individually

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 

                                      S-12

<PAGE>   27




                              DEN NORSKE BANK ASA, individually
                              and as Lead Manager

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                      S-13

<PAGE>   28



                              PARIBAS, individually and as Lead Manager

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                      S-14

<PAGE>   29



                              FIRST UNION NATIONAL BANK,
                              individually and as Lead Manager

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                      S-15

<PAGE>   30



                              BANKERS TRUST COMPANY, as a
                              Lender

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 

                                      S-16

<PAGE>   31



                              CREDIT AGRICOLE INDOSUEZ, as a
                              Lender

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:


 

                                      S-17

<PAGE>   32




                              NATEXIS BANQUE, as a Lender


                              By:
                                 ----------------------------------------------
                              Name:
                              Title:

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                      S-18

<PAGE>   33



                              TORONTO DOMINION (TEXAS), INC.,
                              as a Lender

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:



 

                                      S-19

<PAGE>   34



                                    Exhibit I

               Organization Chart of Borrower and its Subsidiaries



 

                               Exhibit I - Page 1

<PAGE>   35



                                    Exhibit J

                    Form of Designated Officer's Certificate

         Reference is made to (i) the Primary Credit Facility pursuant to that
certain Second Amended and Restated Credit Facility Agreement dated as of March
19, 1999, by and among Borrower, NationsBank, N.A., as Administrative Agent,
CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New York, as
Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the
Co-Agents party thereto, and the Lenders from time to time parties thereto (the
"Primary Credit Agreement") and (ii) the 364 Day Credit Facility pursuant to
that certain Second Amended and Restated Credit Facility Agreement dated as of
March 19, 1999, by and among Borrower, NationsBank, N.A., as Administrative
Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New
York, as Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the
Co-Agents party thereto, and the Lenders from time to time parties thereto (the
"364 Day Credit Agreement" and, together with the Primary Credit Facility, the
"Credit Agreements"). Terms which are defined in the Credit Agreements and which
are used but not defined herein are used herein with the meanings given them in
the Credit Agreements.

         This Certificate is furnished pursuant to Section 5.1(b)(2) of the
Credit Agreements. Together herewith the Borrower is furnishing to Managing
Agents, the Co-Agents and each Lender the Borrower's [FINANCIAL STATEMENTS] (the
"Financial Statements") as of (the "Reporting Date"). The Borrower hereby
represents, warrants, and acknowledges to Agents and each Lender that:

         (a)      the Designated Officer of the Borrower signing this instrument
                  is a duly elected, qualified and acting officer of the
                  Borrower;

         (b)      the Financial Statements are accurate and complete and satisfy
                  the requirements of the Credit Agreements;

         (c)      attached as Schedule I hereto is a schedule of calculations
                  showing compliance (or noncompliance, as the case may be) as
                  of the Reporting Date with the requirements of Sections 5.2(e)
                  and 5.3 of the Credit Agreements; and

         (d)      on the Reporting Date, the Borrower was, and on the date
                  hereof the Borrower is, in full compliance with the disclosure
                  requirements of Section 5.1(d) of the Credit Agreements, and
                  no Default otherwise existed on the Reporting Date or
                  otherwise exists on the date of this Certificate [except for
                  Default(s) under Section(s) of the Credit Agreements, which
                  [is/are] more fully described on a schedule attached hereto].


 

                               Exhibit J - Page 1

<PAGE>   36



         The Designated Officer of the Borrower signing this instrument hereby
certifies that he has reviewed the Loan Documents and the Financial Statements
and has otherwise undertaken such inquiry as is in his opinion necessary to
enable him to express an informed opinion with respect to the above
representations, warranties and acknowledgments of the Borrower and, to the best
of his knowledge, such representations, warranties, and acknowledgments are
true, correct and complete.

                              PIONEER NATURAL RESOURCES
                              COMPANY

                              By:
                                 ----------------------------------------------
                              Name:
                              Title:

                              Date:
                                 ----------------------------------------------



 

                               Exhibit J - Page 2

<PAGE>   37

                                   Schedule I

<TABLE>
==========================================================================================================

COMPLIANCE WITH COVENANTS AS OF              . ($ in 000's)
                                -------------
==========================================================================================================
<S>                                                                                        <C>

A.     SENIOR LEVERAGE RATIO
                                                                                              ============
                      Minimum ratio allowed                       : 1
                                                              ===========
B.     TOTAL LEVERAGE RATIO
                                                                                              ============
                      Minimum ratio allowed                       : 1
                                                              ===========
C.     CONSOLIDATED TANGIBLE NET WORTH
                                                                                              ============
                      Minimum allowed
                                                              ===========
[D.    PROPERTIES NPV TO TOTAL DEBT RATIO
                                                                                              ============
                      Minimum ratio allowed                       : 1      ](1)
                                                              ===========

E.     RESTRICTED PAYMENTS DURING PRECEDING FISCAL QUARTER
                                                                                              ============

==========================================================================================================

COMPUTATION OF FINANCIAL REQUIREMENTS AND RATIOS AS OF
                                                       -----------
==========================================================================================================

A.       SENIOR LEVERAGE RATIO (Section 5.3(a)) ($ in 000's)

               (i)    SENIOR DEBT:

                      (a)       Consolidated Total Debt:       $
                                                                -----------

                      (b)       Less Subordinated Debt:                 $
                                                                         ------------

                      SENIOR DEBT:                                                         $


                                                                                            -----------
</TABLE>


- -----------------------

(1)  Properties NPV to Total Debt Ratio only calculated for Fiscal Quarters
     ending June 30th and December 31st of each Fiscal Year

 

                               Exhibit J - Page 3

<PAGE>   38

<TABLE>
<S>                                                                                        <C>
               (ii)   EBITDAX                                                              $
                                                                                            ===========

         SENIOR LEVERAGE RATIO ((i)(ii))
                                                                                            ===========
                      Minimum ratio allowed                        :1     
                                                              ===========

B.       TOTAL LEVERAGE RATIO (Section 5.3(B)) ($ in 000's)

               (i)    CONSOLIDATED TOTAL DEBT :                                            $
                                                                                            -----------

              (ii)    EBITDAX                                                              $
                                                                                            ===========
         TOTAL LEVERAGE RATIO ((i)(ii))
                                                                                            ===========
                      Minimum ratio allowed                        :1     
                                                              ===========

C.       CONSOLIDATED TANGIBLE NET WORTH (Section 5.3(c)) ($ in 000's)

         CONSOLIDATED TANGIBLE NET WORTH

               (i)    Consolidated shareholder's equity of Borrower
                      and its Subsidiaries                                                 $
                                                                                            -----------

              (ii)    Less Consolidated intangible assets of Borrower
                      and its Subsidiaries                                                 $
                                                                                            -----------

             (iii)    Plus aggregate amount of any non-cash write downs,
                      on a consolidated basis, by Borrower and its Subsidiaries            $
                                                                                            -----------

              (iv)    Plus 50% of the sum of Borrower's and its Subsidiaries
                      Consolidated net income for each Fiscal Quarter beginning
                      with the fiscal quarter ending March 31, 1999                        $
                                                                                            -----------

              (iv)    Plus 85% of the net cash proceeds received by the Borrower
                      and its Subsidiaries from the issuance of any common
                      stock, preferred stock or other equity for each Fiscal
                      Quarter beginning
                      with the Fiscal Quarter ending March 31, 1999.                       $
                                                                                            -----------

                      CONSOLIDATED TANGIBLE NET WORTH                                      $
                                                                                            ===========
                      Minimum allowed
                                                              ===========

[D.      PROPERTIES NPV TO TOTAL DEBT RATIO
                                                                                            ===========

               (i)    PROPERTIES NPV                                                       $
                                                                                            -----------

              (ii)    TOTAL DEBT                                                           $
                                                                                            ===========

         PROPERTIES TO TOTAL DEBT RATIO ((i)(ii))
                                                                                            ===========

                      Minimum ratio allowed                        :1     ](2)
                                                              ===========
</TABLE>








- -------------------

(2)  Properties NPV to Total Debt Ratio only calculated for Fiscal Quarters
     ending June 30th and December 31st of each Fiscal Year




 

                               Exhibit J - Page 4

<PAGE>   39

                                        
                                        
                                        
                                        
                                   Exhibit R
                                        
                                   [Form of]
                                        
                 MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                       AGREEMENT AND FINANCING STATEMENT
                                        
                                      FROM
                                        

                         ______________________________
                           (Taxpayer I.D. No. _____ )
                                        
                                       TO
                                        
                           _________________, Trustee
                                        
                                      AND
                                        
                          _________________ , Trustee
                                        
                                      AND
                                        
                         ____________________________ ,
                              as Collateral Agent
                           (Taxpayer I.D. No. _____ )
                                        
                                        
                       Dated as of ________________, 1999
                                        


- -------------------------------------------------------------------------------

"THIS INSTRUMENT CONTAINS AFTER-ACQUIRED PROPERTY PROVISIONS."

"THIS INSTRUMENT SECURES PAYMENT OF FUTURE ADVANCES."

"THE OIL AND GAS INTERESTS INCLUDED IN THE MORTGAGED PROPERTY WILL BE FINANCED
AT THE WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES DESCRIBED IN EXHIBIT A
HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER
PLACES, IN THE REAL ESTATE RECORDS."

"THOSE PORTIONS OF THE MORTGAGED PROPERTY WHICH ARE MINERALS OR OTHER SUBSTANCES
OF VALUE WHICH MAY BE EXTRACTED FROM THE EARTH (INCLUDING, WITHOUT LIMITATION,
OIL AND GAS), AND THE ACCOUNTS RELATING THERETO, WILL BE FINANCED AT THE
WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES 

 

                               Exhibit R - Page 1

<PAGE>   40

DESCRIBED IN EXHIBIT A HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR
RECORD, AMONG OTHER PLACES, IN THE REAL ESTATE RECORDS."

"THE MORTGAGOR HAS AN INTEREST OF RECORD IN THE REAL ESTATE CONCERNED,
WHICH IS DESCRIBED IN EXHIBIT A HERETO."

"THIS INSTRUMENT IS A LINE OF CREDIT MORTGAGE."

"SOME OF THE PERSONAL PROPERTY CONSTITUTING A PORTION OF THE MORTGAGED PROPERTY
IS OR IS TO BE AFFIXED TO THE PROPERTIES DESCRIBED IN EXHIBIT A HERETO, AND THIS
FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER PLACES, IN THE REAL
ESTATE RECORDS."

"A POWER OF SALE HAS BEEN GRANTED IN THIS MORTGAGE.  A POWER OF SALE MAY
ALLOW THE MORTGAGEE TO TAKE THE MORTGAGED PROPERTY AND SELL IT WITHOUT
GOING TO COURT IN A FORECLOSURE ACTION UPON DEFAULT BY THE MORTGAGOR
UNDER THIS MORTGAGE."

"THE AMOUNT INVOLVED IS $200 OR MORE."

THIS INSTRUMENT WAS PREPARED BY AND
WHEN RECORDED AND/OR FILED
RETURN TO:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, TX  77002




 

                               Exhibit R - Page 2

<PAGE>   41
                 MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                       AGREEMENT AND FINANCING STATEMENT

         THIS MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY AGREEMENT AND
FINANCING STATEMENT, dated as of _________________________, 1999, is from
_______________________________, a _________________ (herein called the
"Mortgagor"), to ____________________ and ____________________, of
______________, ______________, as Trustees (herein collectively called the
"Trustees"), and _____________, a ___________________, having is principal place
of business at ________________, _____________ _____ as collateral agent
(herein, in such capacity, together with any successor(s) thereto in such
capacity, called the "Collateral Agent") for the Lenders and the Noteholders.

         1. For all purposes of this instrument, unless the context otherwise
requires:

                  A. "Borrower" shall mean the "Borrower" as defined in the
Primary Credit Agreement (hereinafter defined) [and the 364-Day Credit Agreement
(hereinafter defined)].

                  B. "Credit Agreement Notes" shall mean the "Notes" as defined
in the Primary Credit Agreement [and the "Notes" as defined in the 364-Day
Credit Agreement].

                  C. "Encumbrance" shall mean any irregularity in title, lien,
security interest, pledge, charge, encumbrance, claim, burden or defect.

                  D. "Hydrocarbons" shall mean oil, gas and other liquid or
gaseous hydrocarbons.

                  E. "Indenture Notes" shall mean each of the following: (i)
Borrower's $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's
$150,000,000 8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes due 2028,
and (v) and other publicly tradeable notes, bonds or debentures outstanding as
of February 1, 1999, which notes, bonds or debentures by their terms require
that they be secured equally and ratably with this instrument.

                  F. "Indenture Trustees" means each of the trustees from time
to time appointed pursuant to the terms of any indenture or similar agreement
governing any of the Indenture Notes.

                  G. "lands described in Exhibit A" shall include any lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference to another instrument or document, and
shall also include any lands now or hereafter unitized or pooled with lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference.

                  H. "Lenders" shall mean the "Lenders" as defined in the
Primary Credit Agreement [and the "Lenders" as defined in the 364-Day Credit
Agreement].

                  I. "Mortgaged Property" shall mean the properties, rights and
interests hereinafter described and defined as the Mortgaged Property.


 

                               Exhibit R - Page 3

<PAGE>   42



                  J. "Noteholders" means any owner or holder of any of the
Indenture Notes from time to time.

                  K. "oil and gas leases" shall include oil, gas and mineral
leases, subleases and assignments thereof, operating rights, and shall also
include subleases and assignments of operating rights.

                  L. "Operating Equipment" shall mean all surface or subsurface
machinery, goods, equipment, fixtures, inventory, facilities, supplies or other
property of whatsoever kind or nature (excluding drilling rigs, trucks,
automotive equipment or other property taken to the premises to drill a well or
for other similar temporary uses) now or hereafter located on or under any of
the lands described in Exhibit A which are useful for the production, gathering,
treatment, processing, storage or transportation of Hydrocarbons (together with
all accessions, additions and attachments to any thereof), including, but not by
way of limitation, all oil wells, gas wells, water wells, injection wells,
casing, tubing, tubular goods, rods, pumping units and engines, christmas trees,
platforms, derricks, separators, compressors, gun barrels, flow lines, tanks,
gas systems (for gathering, treating and compression), pipelines (including
gathering lines, laterals and trunklines), chemicals, solutions, water systems
(for treating, disposal and injection), power plants, poles, lines,
transformers, starters and controllers, machine shops, tools, storage yards and
equipment stored therein, buildings and camps, telegraph, telephone and other
communication systems, roads, loading docks, loading racks and shipping
facilities.

                  M. "Permitted Encumbrances" shall mean any or all of the
following:

                           (i) Lessors' royalties, overriding royalties,
         production payments, net profits interests and similar burdens on
         production from the Mortgaged Property;

                           (ii) Encumbrances that arise under operating
         agreements to secure payment of amounts which are not delinquent and
         are of a type and nature customary in the oil and gas industry;

                           (iii) Encumbrances that arise as a result of pooling
         and unitization agreements, declarations, orders or laws to secure
         payment of amounts which are not delinquent;

                           (iv) Encumbrances securing payments to mechanics and
         materialmen and Encumbrances securing payment of taxes, assessments or
         other governmental charges or levies that, in either case, are not
         delinquent or, if delinquent, are being contested in good faith in the
         normal course of business;

                           (v) consents to assignment by governmental
         authorities (a) that are obtained on or prior to the date hereof or (b)
         that are customarily obtained after the consummation of the
         transactions of the nature contemplated by this instrument;

                           (vi) farmouts, after payment interest and
         conventional rights of reassignment, of a type and nature customary in
         the oil and gas industry, obligating the Mortgagor to assign or
         reassign its interest in any portion of the Mortgaged Property to a
         third party, including

 

                               Exhibit R - Page 4

<PAGE>   43



         in the event it intends to release or abandon such interest prior to
         the expiration of the primary term or other termination of such
         interest;

                           (vii) easements, rights-of-way, servitudes, permits,
         surface leases, surface use restrictions and other surface uses and
         impediments on, over or in respect of any of the Mortgaged Property
         that are not such as to interfere materially with the operation, value
         or use of any of the Mortgaged Property;

                           (viii) calls on or preferential rights to purchase
         production, of a type and nature and at a pricing structure customary
         in the oil and gas industry, held by parties other than the Mortgagor
         and its Subsidiaries;

                           (ix) covenants, conditions and other terms of the oil
         and gas leases and contracts, such covenants, conditions and terms of a
         type and nature customary in the oil and gas business, included in the
         Mortgaged Property;

                           (x) such Encumbrances as the Trustees have expressly
         waived in writing;

                           (xi) rights reserved to or vested in any municipality
         or governmental, tribal, statutory or public authority to control or
         regulate any of the Mortgaged Property in any manner, and all
         applicable laws, rules and orders of any municipality or governmental
         or tribal authority;

                           (xii) such Encumbrances which are validly existing
         and binding upon the Mortgagor's interest in the particular Mortgaged
         Properties as of the date of this Mortgage;

                           (xiii) Encumbrances permitted pursuant to Section
         5.2(b) of [either of] the Credit Agreement[s];

                           (xiv) judgment liens (A) in existence less than 15
         days after the entry thereof or (B) which execution has been stayed or
         the payment of which is covered in full (subject to a customary
         deductible) by insurance;

                           (xv) contractual obligations terminable upon no more
         than 90 days' prior notice to the counterparty thereunder providing for
         the sale of Hydrocarbons produced from the Mortgaged Properties;

                           (xvi) Encumbrances created under this instrument; and

                           (xvii) all other Encumbrances affecting any portion
         of the Mortgaged Property that individually or in the aggregate are not
         such as to interfere materially with the operation, value or use of any
         of the Mortgaged Property.

                  N. "Production Sale Contracts" shall mean contracts now in
effect, or hereafter entered into by the Mortgagor, or entered into by the
Mortgagor's predecessors in interest, for the sale,

 

                               Exhibit R - Page 5

<PAGE>   44

purchase, exchange, gathering, transportation, treating or processing of
Hydrocarbons produced from the lands described in Exhibit A attached hereto and
made a part hereof.

                  O. "Secured Indebtedness" shall have the meaning set forth in
Section 1.2 hereof.

         NOW, THEREFORE, the Mortgagor, for and in consideration of the premises
and of the debts and trusts hereinafter mentioned, has granted, bargained, sold,
warranted, mortgaged, assigned, transferred and conveyed, and by these presents
does grant, bargain, sell, warrant, mortgage, assign, transfer and convey unto
the Trustees, in trust, with power of sale, for use and benefit of the
Collateral Agent for the equal and ratable benefit of the holders of the Secured
Indebtedness, all the Mortgagor's right, title and interest, whether now owned
or hereafter acquired, in and to all of the hereinafter described properties,
rights and interests; and, insofar as such properties, rights and interests
consist of equipment, general intangibles, accounts, contract rights, inventory,
fixtures, proceeds of collateral or any other personal property of a kind or
character defined in or subject to the applicable provisions of the Uniform
Commercial Code (as in effect in the appropriate jurisdiction with respect to
each of said properties, rights and interests), the Mortgagor hereby grants to
said Trustees, for the use and benefit of the Collateral Agent for the equal and
ratable benefit of the holders of the Secured Indebtedness, a security interest
therein; namely:

                  (a) the lands described in Exhibit A, and the oil and gas
         leases, the fee, mineral, overriding royalty, royalty and other
         interests which are specifically described in Exhibit A,

                  (b) the presently existing and (subject to the terms of
         Section 2.6 hereof) hereafter arising unitization, unit operating,
         communitization and pooling agreements and the properties covered and
         the units created thereby (including, without limitation, all units
         formed under orders, regulations, rules, approvals, decisions or other
         official acts of any federal, state or other governmental agency having
         jurisdiction) which are specifically described in Exhibit A or which
         relate to any of the properties and interests specifically described in
         Exhibit A,

                  (c) the Hydrocarbons which are in, under, upon, produced or to
         be produced from the lands described in Exhibit A,

                  (d) the Production Sale Contracts, and

                  (e) the Operating Equipment,

together with any and all corrections or amendments to, or renewals, extensions
or ratifications of, or replacements or substitutions for, any of the same, or
any instrument relating thereto, and all accounts, contracts, contract rights,
options, nominee agreements, operating agreements, processing agreements, farmin
agreements, farmout agreements, joint venture agreements, exploration
agreements, bottomhole agreements, dryhole agreements, support agreements,
acreage contribution agreements, insurance policies, title opinions, title
abstracts, title materials and information, files, records, writings, data
bases, information, systems, logs, well cores, fluid samples, production data
and reports, well testing data and reports, maps, seismic and geophysical,
geological and chemical data and information, interpretative and analytical
reports of any kind or nature, including, without limitation, reserve studies
and reserve evaluations, (to the extent 

 

                               Exhibit R - Page 6

<PAGE>   45


the assignment or release of such agreements, opinions, data, information
systems, logs, cores, samples, and reports is not restricted by any contract or
agreement which is of a type and nature customary in the oil and gas industry)
rights-of-way, franchises, easements, servitudes, surface leases, permits,
licenses, tenements, hereditaments, appurtenances, general intangibles, rents,
issues, profits, products and proceeds, whether now or hereafter existing or
arising, used or useful in connection with, covering, relating to, or arising
from or in connection with, any of the aforesaid in this granting clause
referenced, and all other things of value and incident thereto (including,
without limitation, any and all liens, lien rights, security interests and other
rights and interests) which the Mortgagor might at any time have or be entitled
to, all the aforesaid properties, rights and interests, together with any
additions thereto which may be subjected to the lien and security interest of
this instrument by means of supplements hereto, being hereinafter called the
"Mortgaged Property."

         Subject, however, to (i) the restrictions, exceptions, reservations,
conditions, limitations, interests and other matters, if any, set forth or
referred to in the specific descriptions of such properties and interests in
Exhibit A (including all presently existing royalties, overriding royalties,
payments out of production and other burdens which are referred to in Exhibit A
and which are taken into consideration in computing any percentage, decimal or
fractional interest as set forth in Exhibit A), any Permitted Encumbrances, (ii)
the assignment of production contained in Article III hereof, but only insofar
and so long as said assignment of production is not inoperative under the
provisions of Section 3.1 hereof, and (iii) the condition that none of the
Trustees, the Collateral Agent, the Agents, the Lenders, the Noteholders or any
part thereof shall be liable in any respect for the performance of any covenant
or obligation of the Mortgagor in respect of the Mortgaged Property.

         TO HAVE AND TO HOLD the Mortgaged Property unto the Trustees forever to
secure the payment of the Secured Indebtedness and to secure the performance of
the obligations of the Mortgagor herein contained.

         The Mortgagor, in consideration of the premises, hereby covenants and
agrees with the Trustees and the Collateral Agent as follows:

                                    ARTICLE I
                              Indebtedness Secured

         1.1 Items of Indebtedness Secured. The following items of indebtedness
are secured hereby:

                  (a) that certain Second Amended and Restated Credit Facility
         Agreement - [Primary Facility], dated as of March 19, 1999, by and
         among Pioneer Natural Resources Company (the "Borrower"), NationsBank,
         N.A., as Administrative Agent (the "Administrative Agent"), CIBC Inc.,
         as Documentation Agent, Morgan Guaranty Trust Company of New York, as
         Documentation Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "Primary Credit Agreement"), which
         includes, without limitation, the Notes (as defined in the Primary
         Credit Agreement), Obligations (as defined in the Primary Credit


 

                               Exhibit R - Page 7

<PAGE>   46


         Agreement) and liabilities of the Borrower under and in connection with
         the Primary Credit Agreement;

                  (b) [that certain Second Amended and Restated Credit Facility
         Agreement - [364- Day Facility], dated as of March 19, 1999, by and
         among Borrower, the Administrative Agent, CIBC Inc., as Documentation
         Agent, Morgan Guaranty Trust Company of New York, as Documentation
         Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "364-Day Credit Agreement", and
         together with the Primary Credit Agreement, the "Credit Agreements"),
         which includes, without limitation, the Notes (as defined in the
         364-Day Credit Agreement), Obligations (as defined in the 364-Day
         Credit Agreement) and liabilities of the Borrower under and in
         connection with the 364-Day Credit Agreement;

                  (c)] The Indenture Notes;

                  (d) Any promissory note taken in extension or renewal of or in
         replacement or substitution for any of the Credit Agreement Notes or
         the Indenture Notes; and

                  (e) Any sums advanced or expenses or costs incurred by the
         Trustees or the Collateral Agent which are made or incurred pursuant
         to, or permitted by, the terms hereof, plus interest thereon at the
         rate herein specified or otherwise agreed upon, from the date of the
         advances or the incurring of such expenses or costs until reimbursed.

         1.2 Secured Indebtedness Defined. All the above items of indebtedness
are hereinafter collectively referred to as the "Secured Indebtedness."

                                   ARTICLE II
                       Particular Covenants and Warranties
                                of the Mortgagor

         2.1 Payment of the Secured Indebtedness. The Mortgagor will duly and
punctually pay the Secured Indebtedness, including each and every obligation
owing on account of the Credit Agreement Notes and the Indenture Notes.

         2.2 Warranties. The Mortgagor warrants and represents to the Trustees
and the Collateral Agent that (a) the oil and gas leases described in Exhibit A
hereto are valid, subsisting leases, superior and paramount to all other oil and
gas leases respecting the properties to which they pertain, (b) all producing
wells located on the lands described in Exhibit A have been drilled, operated
and produced in substantial compliance with all applicable laws, rules and
regulations of all authorities having jurisdiction and such wells are in fact
bottomed under and are producing from the lands described in Exhibit A or from
units in which such lands are unitized or pooled, (c) the Mortgagor has valid
and indefeasible title to each property right or interest constituting the
Mortgaged Property and has a good and legal right to grant and convey the same
to the Trustees, and (d) the Mortgaged Property is free from all encumbrances or
liens whatsoever, except for Permitted Encumbrances or as permitted by the
provisions of Section 2.5(f) hereof. 
 

                               Exhibit R - Page 8

<PAGE>   47


The Mortgagor will warrant and forever defend the Mortgaged Property unto the
Trustees against every person whomsoever lawfully claiming the same or any part
thereof, and the Mortgagor will maintain and preserve the lien and security
interest hereby created so long as any of the Secured Indebtedness remains
unpaid.

         2.3 Further Assurances. The Mortgagor will execute and deliver such
other and further instruments and will do such other and further acts as in the
opinion of the Trustees or the Collateral Agent may be necessary or desirable to
carry out more effectually the purposes of this instrument, including, without
limiting the generality of the foregoing, (a) proceeding with reasonable
diligence to promptly correct any Encumbrance which may hereafter be discovered
in the title to the Mortgaged Property other than Permitted Encumbrances, (b)
prompt correction of any defect in the execution and acknowledgment of this
instrument, and (c) prompt execution and delivery of all notices to parties
producing, purchasing or receiving proceeds of production from the Mortgaged
Property, and all division orders or transfer orders, any of which, in the
opinion of the Trustees or the Collateral Agent, is needed to transfer
effectually or to assist in transferring effectually to the Collateral Agent the
assigned proceeds of production from the Mortgaged Property.

         2.4 Taxes. Subject to the Mortgagor's right to contest the same, the
Mortgagor will promptly pay all taxes, assessments and governmental charges
legally imposed upon this instrument or upon the Mortgaged Property, or upon the
interest of the Trustees or the Collateral Agent, or upon the income and profits
thereof.

         2.5 Recording, etc. The Mortgagor will promptly, and at the Mortgagor's
expense, record, register, deposit and file this and every other instrument in
addition or supplemental hereto in such offices and places and at such times and
as often as may be necessary to preserve, protect and renew the lien and
security interest hereof as a first lien on and prior perfected security
interest in real or personal property, as the case may be, subject to the
Permitted Encumbrances, and the rights and remedies of the Trustees and of the
Collateral Agent, and otherwise will do and observe all things or matters
necessary or expedient to be done or observed by reason of any law or regulation
of any State or of the United States of America or of any other competent
authority, for the purpose of effectively creating, maintaining and preserving
the lien and security interest hereof on and in the Mortgaged Property, subject
to the Permitted Encumbrances.

         2.6 Pooling and Unitization of Mortgaged Property. Mortgagor shall have
the right, and is hereby authorized, without notice or consent to pool or
unitize all or any part of any tract of land described in Exhibit A, insofar as
related to the Mortgaged Property, with adjacent lands, leaseholds and other
interests, or enter into joint exploration or development agreements, when, in
the reasonable judgment of the Mortgagor, it is necessary or advisable to do so
in order to form a drilling unit to facilitate the orderly development of that
part of the Mortgaged Property affected thereby, or to comply with the
requirements of any law or governmental order or regulation relating to the
spacing of wells or proration of the production therefrom. Any unit so formed
may relate to one or more zones or horizons, and a unit formed for a particular
zone or horizon need not conform in area to any other unit relating to a
different zone or horizon, and a unit formed for the production of oil need not
conform in area with any unit formed for the production of gas. Upon written
request of the Trustees or the Collateral Agent, Mortgagor shall make available
to the Trustee and the Collateral Agent copies of all such existing pooling
agreements, declarations of pooling or other instruments creating such units.
The interest in any such unit attributable 


 

                               Exhibit R - Page 9

<PAGE>   48


to the Mortgaged Property (or any part thereof) included therein shall become a
part of the Mortgaged Property and shall be subject to the lien hereof in the
same manner and with the same effect as though such unit and the interest of the
Mortgagor therein were specifically described in Exhibit A.

         2.7 Right of Entry. The Mortgagor will permit the Trustees and the
Collateral Agent, or the agents of any of them, to enter upon the Mortgaged
Property, and all parts thereof, for the purpose of investigating and inspecting
the condition and operation thereof.

                                   ARTICLE III
                            Assignment of Production

         3.1 Assignment. As further security for the payment of the Secured
Indebtedness, the Mortgagor hereby transfers, assigns, warrants and conveys to
the Collateral Agent for the equal and ratable benefit of the holders of Secured
Indebtedness, effective as of the date hereof, at 7:00 A.M., local time, all
Hydrocarbons which are thereafter produced from and which accrue to the
Mortgaged Property, and all proceeds therefrom. All parties producing,
purchasing or receiving any such Hydrocarbons, or having such, or proceeds
therefrom, in their possession for which they or others are accountable to the
Collateral Agent by virtue of the provisions of this Article, are authorized and
directed to treat and regard the Collateral Agent as the assignee and transferee
of the Mortgagor and entitled in the Mortgagor's place and stead to receive such
Hydrocarbons and all proceeds therefrom; and said parties and each of them shall
be fully protected in so treating and regarding the Collateral Agent and shall
be under no obligation to see to the application by the Collateral Agent of any
such proceeds or payments received by it. Notwithstanding the other provisions
of this Article including the foregoing provisions of this Section 3.1, the
Collateral Agent or any receiver appointed in judicial proceedings for the
enforcement of this instrument shall have the right to receive all of the
Hydrocarbons herein assigned and the proceeds therefrom only after any event of
default as described in the provisions of Section 4.1 hereof shall have occurred
and be continuing. Upon any sale of the Mortgaged Property or any part thereof
pursuant to Article V, the Hydrocarbons thereafter produced from the property so
sold, and the proceeds therefrom, shall be included in such sale and shall pass
to the purchaser free and clear of the assignment contained in this Article.

         3.2 Application of Proceeds. All payments received by the Collateral
Agent pursuant to Section 3.1 hereof shall be placed in a cash collateral
account at the principal office of the Collateral Agent and on the first
Business Day (as defined in the Credit Agreements) of each calendar month
applied as follows:

                  First: To the payment and satisfaction of all costs and
         expenses incurred in connection with the collection of such proceeds,
         and to the payment of all items of the Secured Indebtedness not
         evidenced by any Credit Agreement Note or any Indenture Note.

                  Second: To the payment of those items of the Secured
         Indebtedness then due and owing, pro rata according to each Secured
         Indebtedness holder's percentage of such items outstanding at the time
         of such payment.

                  Third: The balance, if any, shall be released to the
         Mortgagor.



 

                               Exhibit R - Page 10

<PAGE>   49


         3.3 No Liability of the Collateral Agent in Collecting. The Collateral
Agent is hereby absolved from all liability for failure to enforce collection of
any proceeds so assigned (and no such failure shall be deemed to be a waiver of
any right of the Collateral Agent or the Trustees) and from all
other responsibility in connection therewith, except the responsibility to
account to the Mortgagor for funds actually received.

         3.4 Assignment Not a Restriction on the Collateral Agent's Rights.
Nothing herein contained shall detract from or limit the absolute obligation of
the Mortgagor to make payment of the Secured Indebtedness regardless of whether
the proceeds assigned by this Article are sufficient to pay the same, and the
rights under this Article shall be in addition to all other security now or
hereafter existing to secure the payment of the Secured Indebtedness.

         3.5 Indemnity. The Mortgagor agrees to indemnify the Trustees and the
Collateral Agent against all claims, actions, liabilities, judgments, costs,
attorneys' fees or other charges of whatsoever kind or nature (all hereinafter
in this Section 3.6 called "claims") made against or incurred by them or any of
them as a consequence of the assertion, either before or after the payment in
full of the Secured Indebtedness, that they or any of them received Hydrocarbons
herein assigned or the proceeds thereof claimed by third persons, and the
Trustees and the Collateral Agent shall have the right to defend against any
such claims, employing attorneys therefor, and unless furnished with reasonable
indemnity, they or any of them shall have the right to pay or compromise and
adjust all such claims. The Mortgagor will indemnify and pay to the Trustees or
the Collateral Agent, as the case may be, any and all such amounts as may be
paid in respect thereof or as may be successfully adjudged against the Trustees
or the Collateral Agent or any of them. The obligations of the Mortgagor as
hereinabove set forth in this Section 3.5 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

                                   ARTICLE IV
                                Events of Default

         4.1 Events of Default Hereunder. Default in the payment of principal of
any Secured Indebtedness when due or default (and such default shall continue
unremedied for five (5) days or such longer period during which the holders
thereof, or any Indenture Trustee for the holders thereof, do not have the power
to cause such Secured Indebtedness to become immediately payable in full) in the
payment of interest on any Secured Indebtedness when due, so long as such
default shall not have been remedied shall be an "event of default" hereunder.

                                    ARTICLE V
                           Enforcement of the Security

         5.1 Power of Sale of Real Property Constituting a Part of the Mortgaged
Property. Upon the occurrence of an event of default and if such event shall be
continuing, the Trustees shall have the right and power to sell, to the extent
permitted by law, at one or more sales, as an entirety or in parcels, as they
may elect, the real property constituting a part of the Mortgaged Property, at
such place or places and otherwise in such manner and upon such notice as may be
required by law, or, in the absence of any such requirement, as the Trustees may
deem appropriate, and to make conveyance to the purchaser or purchasers; and the
Mortgagor shall warrant title to such real property, subject to Permitted
Encumbrances, to such purchaser or purchasers. Any public sale may be adjourned
without the necessity of announcement 
 

                               Exhibit R - Page 11

<PAGE>   50


at the time and place of such sale and without public notice except as may be
required by law. The Trustee may sell, transfer and convey any part of the
Mortgaged Property on such terms of credit or part cash and part credit, secured
by contract or agreement for sale or mortgage, or otherwise as shall appear to
the Trustee to be most advantageous and for such price or prices as can
reasonably be obtained therefor, and in the event of a sale on credit or for
part cash or part credit, whether by way of contract for sale or by conveyance
or transfer and mortgage, neither the Trustee, nor Collateral Agent or holders
of Secured Indebtedness are to be accountable for or charged with any monies
until the same shall actually be received in cash. The right of sale hereunder
shall not be exhausted by one or any sale, and the Trustees may make other and
successive sales until all of the trust estate be legally sold. If the proceeds
of such sale or sales of less than the whole of the Mortgaged Property shall be
less than the aggregate of the indebtedness secured hereby and the expense of
executing this trust as provided herein, this Mortgage and the lien and charge
hereof shall remain in full force and effect as to the unsold portion of the
Mortgaged Property just as though no sale had been made; provided, however, that
the Mortgagor shall never have any right to require the sale of less than the
whole of the Mortgaged Property but the Collateral Agent shall have the right,
at its election, to request the Trustee to sell less than the whole of the
Mortgaged Property. With respect to that portion, if any, of the Mortgaged
Property situated in the State of Wyoming, this instrument may be foreclosed by
advertisement and sale as provided by applicable Wyoming statutes. With respect
to that portion, if any, of the Mortgaged Property situated in the State of
Oklahoma, the Collateral Agent shall have the right and power at its option to
declare the Secured Indebtedness hereby secured due and payable and to sell, or
direct the Trustees to sell, the "real estate," as such term is defined under
the provisions of 46 O.S. Supp. 1986, ss.42, constituting a part of the
Mortgaged Property, all under the terms of 46 O.S. Supp. 1986, ss.40 et seq.,
and shall, to the extent permitted by law, have the other rights conferred on
the Trustees under the provisions of this instrument.

         5.2 Rights of the Trustees with Respect to Personal Property
Constituting a Part of the Mortgaged Property. Upon the occurrence of an event
of default and if such event shall be continuing, the Trustees will have all
rights and remedies granted by law, and particularly by the Uniform Commercial
Code, including, but not limited to, the right to take possession of all
personal property constituting a part of the Mortgaged Property, and for this
purpose the Trustees may enter upon any premises on which any or all of such
personal property is situated and take possession of and operate such personal
property (or any portion thereof) or remove it therefrom. The Trustees may
require the Mortgagor to assemble such personal property and make it available
to the Trustees at a place to be designated by the Trustees which is reasonably
convenient to all parties. Unless such personal property is perishable or
threatens to decline speedily in value or is of a type customarily sold on a
recognized market, the Trustees will give the Mortgagor reasonable notice of the
time and place of any public sale or of the time after which any private sale or
other disposition of such personal property is to be made. This requirement of
sending reasonable notice will be met if the notice is mailed by first-class
mail, postage prepaid, to the Mortgagor at the address shown below the
signatures at the end of this instrument at least five (5) days before the time
of the sale or disposition.

         5.3 Rights of the Trustees with Respect to Fixtures Constituting a Part
of the Mortgaged Property. Upon the occurrence of an event of default and if
such event shall be continuing, the Trustees may elect to treat the fixtures
constituting a part of the Mortgaged Property as either real property collateral
or personal property collateral and then proceed to exercise such rights as
apply to such type of collateral.


 

                               Exhibit R - Page 12

<PAGE>   51


         5.4 Judicial Proceedings. Upon occurrence of an event of default and if
such event shall be continuing, the Trustees, in lieu of or in addition to
exercising any power of sale hereinabove given, may proceed by a suit or suits
in equity or at law, whether for a foreclosure hereunder, or for the sale of the
Mortgaged Property, or for the specific performance of any covenant or agreement
herein contained or in aid of the execution of any power herein granted, or for
the appointment of a receiver pending any foreclosure hereunder or the sale of
the Mortgaged Property, or for the enforcement of any other appropriate legal or
equitable remedy.

         5.5 Possession of the Mortgaged Property. It shall not be necessary for
the Trustees to have physically present or constructively in their possession at
any sale held by the Trustees or by any court, receiver or public officer any or
all of the Mortgaged Property; and the Mortgagor shall deliver to the purchasers
at such sale on the date of sale the Mortgaged Property purchased by such
purchasers at such sale, and if it should be impossible or impracticable for any
of such purchasers to take actual delivery of the Mortgaged Property, then the
title and right of possession to the Mortgaged Property shall pass to such
purchaser at such sale as completely as if the same had been actually present
and delivered.

         5.6 Certain Aspects of a Sale. Each Lender or Noteholder shall have the
right to become the purchaser at any sale held by the Trustees or by any court,
receiver or public officer, and such Lender shall have the right to credit upon
the amount of the bid made therefor the amount payable out of the net proceeds
of such sale to it. Recitals contained in any conveyance made to any purchaser
at any sale made hereunder shall conclusively establish the truth and accuracy
of the matters therein stated, including, without limiting the generality of the
foregoing, nonpayment of the unpaid principal sum of, and the interest accrued
on, the Secured Indebtedness after the same have become due and payable,
advertisement and conduct of such sale in the manner provided herein or
appointment of any successor Trustee hereunder.

         5.7 Receipt to Purchaser. Upon any sale, whether made under the power
of sale herein granted and conferred or by virtue of judicial proceedings, the
receipt of the Trustees, or of the officer making sale under judicial
proceedings, shall be sufficient discharge to the purchaser or purchasers at any
sale for his or their purchase money, and such purchaser or purchasers, or his
or their assigns or personal representatives, shall not, after paying such
purchase money and receiving such receipt of the Trustees or of such officer
therefor, be obliged to see to the application of such purchase money, or be in
anywise answerable for any loss, misapplication or nonapplication thereof.

         5.8 Effect of Sale. Any sale or sales of the Mortgaged Property,
whether under the power of sale herein granted and conferred or by virtue of
judicial proceedings, shall operate to divest all right, title, interest, claim
and demand whatsoever either at law or in equity, of the Mortgagor of, in and to
the premises and the property sold, and shall be a perpetual bar, both at law
and in equity, against the Mortgagor, and the Mortgagor's successors or assigns,
and against any and all persons claiming or who shall thereafter claim all or
any of the property sold from, through or under the Mortgagor or the Mortgagor's
successors or assigns. Nevertheless, the Mortgagor, if requested by the Trustees
so to do, shall join in the execution and delivery of all proper conveyances,
assignments and transfers of the properties so sold.


 

                               Exhibit R - Page 13

<PAGE>   52


         5.9 Application of Proceeds. The proceeds of any sale of the Mortgaged
Property, or any part thereof, whether under the power of sale herein granted
and conferred or by virtue of judicial proceedings, shall be applied as follows:

                  First: To the payment and satisfaction of all reasonable costs
         and expenses incurred by the Trustees in the performance of their
         duties including, without limiting the generality of the foregoing,
         costs and expenses of any entry, or taking of possession, of any sale,
         or advertisement thereof, and of conveyances, and as well, court costs,
         compensation of agents and employees and reasonable legal fees.

                  Second: To a payment to the Collateral Agent, equal in amount
         to the Secured Indebtedness outstanding at the time of the payment.

                  Third: Any surplus thereafter remaining shall be paid to the
         Mortgagor or the Mortgagor's successors or assigns, as their interests
         shall appear.

         All payments to the Collateral Agent shall be paid into such account as
the Collateral Agent shall specify from time to time by notice to the Trustees,
in same day or immediately available funds. The Collateral Agent shall promptly
remit in same day funds to each holder of Secured Indebtedness its pro rata
share, based on the amount of outstanding Secured Indebtedness owed to it, of
such payments received by the Collateral Agent.

         5.10 The Mortgagor's Waiver of Appraisement, Marshalling and Other
Rights. The Mortgagor agrees, to the full extent that the Mortgagor may lawfully
so agree, that the Mortgagor will not at any time insist upon or plead or in any
manner whatever claim the benefit of any appraisement, valuation, stay,
extension or redemption law now or hereafter in force, in order to prevent or
hinder the enforcement or foreclosure of this instrument or the absolute sale of
the Mortgaged Property or the possession thereof by any purchaser at any sale
made pursuant to any provision hereof, or pursuant to the decree of any court of
competent jurisdiction; but the Mortgagor, for the Mortgagor and all who may
claim through or under the Mortgagor, so far as the Mortgagor or those claiming
through or under the Mortgagor now or hereafter lawfully may, hereby waives the
benefit of all such laws; provided, however, that appraisement of any of the
Mortgaged Property located in the State of Oklahoma is hereby expressly waived
or not, at the option of the Trustees, such option to be exercised prior to or
at the time the judgment is rendered in any foreclosure hereof. The Mortgagor,
for the Mortgagor and all who may claim through or under the Mortgagor, waives,
to the extent that the Mortgagor may lawfully do so, any and all right to have
the Mortgaged Property marshalled upon any foreclosure of the lien hereof, or
sold in inverse order of alienation, and agrees that the Trustees or any court
having jurisdiction to foreclose such lien may sell the Mortgaged Property as an
entirety. The Mortgagor, for the Mortgagor and all who may claim through or
under the Mortgagor, further waives, to the full extent that the Mortgagor may
lawfully do so, any requirement for posting a receiver's bond or replevin bond
or other similar type of bond if the Trustees commence an action for appointment
of a receiver or an action for replevin to recover possession of any of the
Mortgaged Property. If any law in this paragraph referred to and now in force,
of which the Mortgagor or the Mortgagor's successor or successors might take
advantage despite the provisions hereof, shall hereafter be repealed or cease to
be in force, such law shall not thereafter be deemed to constitute any part of
the contract herein contained or to preclude the operation or application of the
provisions of this 
 

                               Exhibit R - Page 14

<PAGE>   53


paragraph. Pursuant to Section 39-5-19, New Mexico Statutes, Annotated, 1978
Comp., as amended, the Mortgagor agrees that as to the Mortgaged Property
situated in the State of New Mexico, the redemption period shall be shortened to
one (1) month. The Mortgagor hereby waives all rights of appraisement, sale,
homestead or redemption allowed under any law or laws of the State of Arkansas,
and especially redemption under the Act of the General Assembly of the State of
Arkansas approved May 8, 1899, and acts amendatory thereto.

         5.11 Costs and Expenses. All reasonable costs and expenses (including
reasonable attorneys' fees) incurred by the Trustees and the Collateral Agent in
protecting and enforcing their rights hereunder, shall constitute a demand
obligation owing by the Mortgagor to the party incurring such costs and expenses
and shall draw interest at an annual rate equal to the "Prime Rate" (the "Prime
Rate") as published in the Wall Street Journal from time to time (or if for a
day when such rate is note so published, at the rate for the next preceding day
when so published) from time to time plus two percent (2%) until paid, all of
which shall constitute a portion of the Secured Indebtedness.

         5.12 Sale of the Mortgaged Property in Mississippi. After the
occurrence of an event of default, the Trustees, their successors or
substitutes, are authorized and empowered, and it shall be their special duty at
the request of the Collateral Agent (which request is hereby presumed), to
enforce this trust and to sell the Mortgaged Property located in the State of
Mississippi, as an entirety or in parcels, as the Trustees acting may designate,
to satisfy the Secured Indebtedness then unpaid, after having published notice
of the day, time, place and terms of sale in some newspaper published in the
county or counties, as the case may be, in which the Mortgaged Property in the
State of Mississippi is situated for three (3) consecutive weeks preceding date
of sale, and by posting one notice of such sale at the Court House of each
county in which the Mortgaged Property is situated for said period of time. In
the event the Mortgaged Property is located in more than one county or in two
judicial districts of the same county in the State of Mississippi, the Trustees
or their substitutes or successors in trust shall have the power, in case they
are directed to foreclose under this instrument, to select the county or
judicial district in which the sale shall be made and their selection shall be
binding on the Mortgagor and the holders of Secured Indebtedness and all persons
claiming through or under them, whether by contract or law. The Trustees or
their substitutes or any successors in said Trust shall have full power to fix
the day, time, place and terms of sale and may appoint or delegate any one or
more persons as agent to perform any act or acts necessary or incident to any
sale held by the Trustees, including the posting of notices and the conduct of
sale, but in the name and on behalf of the Trustees, their substitutes or
successors. The Mortgagor waives the provisions of Section 89-1-55 of the
Mississippi Code of 1972, Recompiled, and Laws amendatory thereto, if any, as
far as said section restricts the right of the Trustees to offer at sale more
than 160 acres at one time, and the Trustees, their substitutes or successors
may, in their discretion, offer the Mortgaged Property as a whole or in such
part or parts as they may deem desirable, regardless of the manner in which it
may be described. Any sale made by the Trustees hereunder may be adjourned by
announcement at the time and place appointed for such sale without further
notice except as may be required by law.

         5.13 Sale of the Mortgaged Property in Texas. If any Credit Agreement
Note or any Indenture Note is not paid when due, whether by acceleration or
otherwise, the Trustees are hereby authorized and empowered to sell any part of
the Mortgaged Property located in the State of Texas at public sale to the
highest bidder for cash in the area at the county courthouse of the county in
Texas in which the Texas portion of the Mortgaged Property or any part thereof
is situated, as herein described, designated by such 
 

                               Exhibit R - Page 15

<PAGE>   54


county's commissioner's court for such proceedings, or if no area is so
designated, at the door of the county courthouse of said county, at a time
between the hours of 10:00 A.M. and 4:00 P.M. which is no later than three (3)
hours after the time stated in the notice described immediately below as the
earliest time at which such sale would occur on the first Tuesday of any month,
after advertising the earliest time at which said sale would occur, the place,
and terms of said sale, and the portion of the Mortgaged Property to be sold, by
(a) posting (or by having some person or persons acting for the Trustees post)
for at least twenty-one (21) days preceding the date of the sale, written or
printed notice of the proposed sale at the courthouse door of said county in
which the sale is to be made; and if such portion of the Mortgaged Property lies
in more than one county, one such notice of sale shall be posted at the court
house door of each county in which such part of the Mortgaged Property is
situated and such part of the Mortgaged Property may be sold in the area at the
county courthouse of any one of such counties designated by such county's
commissioner's court for such proceedings, or if no area is designated, at the
courthouse door of such county, and the notice so posted shall designate in
which county such property shall be sold, and (b) filing in the office of the
county clerk of each county in which any part of the Texas portion of the
Mortgaged Property which is to be sold at such sale is situated a copy of the
notice posted in accordance with the preceding clause (a). In addition to such
posting and filing of notice, the Collateral Agent, acting on behalf of the
holders of the Secured Indebtedness shall, at least twenty-one (21) days
preceding the date of sale, serve or cause to be served written notice of the
proposed sale by certified mail on the Mortgagor and on each other debtor, if
any, obligated to pay the Secured Indebtedness according to the records of the
Collateral Agent, the Lenders, the Noteholders or other holders of the Secured
Indebtedness. Service of such notice shall be completed upon deposit of the
notice, enclosed in a postpaid wrapper properly addressed to the Mortgagor and
such other debtors at their most recent address or addresses as shown by the
records of the Collateral Agent in a post office or official depository under
the care and custody of the United States Postal Service. The affidavit of any
person having knowledge of the facts to the effect that such a service was
completed shall be prima facie evidence of the fact of service. The Mortgagor
agrees that no notice of any sale, other than as set out in this paragraph, need
be given by the Trustees, the Collateral Agent or any other person. The
Mortgagor hereby designates as its address for the purpose of such notice the
address set out on the signature page hereof; and agrees that such address shall
be changed only by depositing notice of such change enclosed in a postpaid
wrapper in a post office or official depository under the care and custody of
the United States Postal Service, certified mail, postage prepaid, return
receipt requested, addressed to the Collateral Agent at the address for the
Collateral Agent set out herein (or to such other address as the Collateral
Agent may have designated by notice given as above provided to the Mortgagor and
such other debtors). Any such notice of change of address of the Mortgagor or
other debtors or of the Collateral Agent shall be effective three (3) Business
Days after such deposit if such post office or official depository is located in
the State of Texas, otherwise to be effective upon receipt. The Mortgagor
authorizes and empowers the Trustees to sell the Texas portion of the Mortgaged
Property in lots or parcels or in its entirety as the Trustees shall deem
expedient; and to execute and deliver to the purchaser or purchasers thereof
good and sufficient deeds of conveyance thereto by fee simple title, with
evidence of general warranty by the Mortgagor, and the title of such purchaser
or purchasers when so made by the Trustees, the Mortgagor binds itself to
warrant and forever defend. Where portions of the Mortgaged Property lie in
different counties, sales in such counties may be conducted in any order that
the Trustees may deem expedient; and one or more such sales may be conducted in
the same month, or in successive or different months as the Trustees may deem
expedient. Notwithstanding anything to the contrary contained herein, the
Trustees may postpone the sale provided for in this Section 5.13 at any time
without the necessity of a public announcement. The provisions hereof 

 

                               Exhibit R - Page 16

<PAGE>   55


with respect to the posting and giving of notices of sale are intended to comply
with the provisions of Section 51.002 of the Property Code of the State of
Texas, as in force and effect on January 1, 1992, and in the event the
requirements, or any notice, under such Section 51.002 of the Property Code of
the State of Texas shall be eliminated or the prescribed manner of giving such
notices modified by future amendment to, or adoption of any statute superseding,
Section 51.002 of the Property Code of the State of Texas, the requirement for
such particular notices shall be deemed stricken from or modified in this
instrument in conformity with such amendment or superseding statute, effective
as of the effective date thereof.

         5.14 Operation of the Mortgaged Property by the Trustees. Upon the
occurrence of an event of default and so long as such event of default is
continuing and in addition to all other rights herein conferred on the Trustees,
the Trustees (or any person, firm or corporation designated by the Trustees)
shall have the right and power, but shall not be obligated, to enter upon and
take possession of any of the Mortgaged Property, and to exclude the Mortgagor,
and the Mortgagor's agents or servants, wholly therefrom, and to hold, use,
administer, manage and operate the same to the extent that the Mortgagor shall
be at the time entitled and in its place and stead. The Trustees, or any person,
firm or corporation designated by the Trustees, may operate the same without any
liability to the Mortgagor in connection with such operations, except to use
ordinary care in the operation of such properties, and the Trustees or any
person, firm or corporation designated by the Trustees, shall have the right to
collect, receive and receipt for all Hydrocarbons produced and sold from said
properties, to make repairs, purchase machinery and equipment, conduct work-over
operations, drill additional wells and to exercise every power, right and
privilege of the Mortgagor with respect to the Mortgaged Property. When and if
the expenses of such operation and development (including costs of unsuccessful
work-over operations or additional wells) have been paid and the Secured
Indebtedness paid, said properties shall, if there has been no sale or
foreclosure, be returned to the Mortgagor.

                                   ARTICLE VI
                            Miscellaneous Provisions

         6.1 Successor Trustees. Any Trustee may resign in writing addressed to
the Collateral Agent or may be removed at any time with or without cause by an
instrument in writing duly executed by the Collateral Agent. In case of the
death, resignation or removal of a Trustee, one or more successor Trustees may
be appointed by the Collateral Agent by instrument of substitution complying
with any applicable requirements of law, and in the absence of any such
requirement without formality other than appointment and designation in writing.
Such appointment and designation shall be full evidence of the right and
authority to make the same and of all facts therein recited, and upon the making
of any such appointment and designation this conveyance shall vest in the named
successor Trustee or Trustees all the estate and title of the prior Trustee in
all of the Mortgaged Property, and he or they shall thereupon succeed to all the
rights, powers, privileges, immunities and duties hereby conferred upon the
prior Trustee. All references herein to the Trustees shall be deemed to refer to
the Trustees from time to time acting hereunder.

         6.2 Actions or Advances by the Collateral Agent or the Trustees. Each
and every covenant herein contained shall be performed and kept by the Mortgagor
solely at the Mortgagor's expense. If the Mortgagor shall fail to perform or
keep any of the covenants of whatsoever kind or nature contained in this
instrument, the Collateral Agent, the Trustees or any receiver appointed
hereunder, may, but shall not be 
 

                               Exhibit R - Page 17

<PAGE>   56


obligated to, take action and/or make advances to perform the same in the
Mortgagor's behalf, and the Mortgagor hereby agrees to repay the expense of such
action and such advances upon demand plus interest at an annual rate equal to
the Prime Rate plus two percent (2%) until paid or, in the event any promissory
note evidences such indebtedness, upon the terms and conditions thereof. No such
advance or action by the Collateral Agent, the Trustees or any receiver
appointed hereunder shall be deemed to relieve the Mortgagor from any default
hereunder.

         6.2 Defense of Claims. The Mortgagor will notify the Trustees, in
writing, promptly of the commencement of any legal proceedings affecting the
lien or security interest hereof or the Mortgaged Property, or any part thereof,
and will take such action, employing attorneys agreeable to the Trustees and the
Collateral Agent, as may be necessary or appropriate to preserve the
Mortgagor's, the Trustees' and the Collateral Agent's rights affected thereby
and/or to hold harmless the Trustees or the Collateral Agent in respect of such
proceedings; and should the Mortgagor fail or refuse to take any such action,
the Trustees or the Collateral Agent may, upon giving prior written notice
thereof to the Mortgagor, take such action in behalf and in the name of the
Mortgagor and at the Mortgagor's expense. The obligations of the Mortgagor as
hereinabove set forth in this Section 6.3 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

         6.3 The Mortgaged Property to Revert. If the Secured Indebtedness shall
be fully paid and all the commitments and obligations of the Lenders under the
Credit Agreements shall have been terminated in writing and the covenants herein
contained and contained in the Credit Agreements shall be well and truly
performed, then all of the Mortgaged Property shall revert to the Mortgagor and
the entire estate, right, title and interest of the Trustees and the holders of
Secured Indebtedness shall thereupon cease; and the Trustees and the Collateral
Agent in such case shall, upon the request of the Mortgagor and at the
Mortgagor's cost and expense, deliver to the Mortgagor proper instruments
acknowledging satisfaction of this instrument. The foregoing notwithstanding,
this instrument is a Line of Credit Mortgage and until the termination in
writing of the Credit Agreements and the occurrence of the other events
described in the past sentence of this Section, this Mortgage, and the priority
and perfection of the liens created hereunder should continue in full force and
effect even if at any time or from time to time there are no moneys outstanding
under the Credit Agreements.

         6.4 Renewals, Amendments and Other Security. Renewals and extensions of
the Secured Indebtedness may be given at any time and amendments may be made to
agreements relating to any part of such Secured Indebtedness or the Mortgaged
Property and the Trustees and the holders of Secured Indebtedness may take or
may now hold other security for the Secured Indebtedness, all without notice to
or consent of the Mortgagor. The Trustees or the holders of Secured Indebtedness
may resort first to such other security or any part thereof or first to the
security herein given or any part thereof, or from time to time to either or
both, even to the partial or complete abandonment of either security, and such
action shall not be a waiver of any rights conferred by this instrument, which
shall continue as a first lien upon and prior perfected security interest in the
Mortgaged Property not expressly released until the Secured Indebtedness is
fully paid.

         6.5 Instrument an Assignment, etc. This instrument shall be deemed to
be and may be enforced from time to time as an assignment, chattel mortgage,
contract, deed of trust, financing statement, real estate mortgage, or security
agreement, and from time to time as any one or more thereof.


 

                               Exhibit R - Page 18

<PAGE>   57


         6.6 Limitation on Interest. No provision of this instrument shall
require the payment or permit the collection of interest in excess of the
maximum permitted by applicable law or which is otherwise contrary to law. If
any excess of interest in such respect is herein provided for, or shall be
adjudicated to be so provided for herein, the Mortgagor shall not be obligated
to pay such excess.

         6.7 Unenforceable or Inapplicable Provisions. If any provision hereof
is invalid or unenforceable in any jurisdiction, the other provisions hereof
shall remain in full force and effect in such jurisdiction, and the remaining
provisions hereof shall be liberally construed in favor of the Trustees and the
Collateral Agent in order to effectuate the provisions hereof, and the
invalidity of any provision hereof in any jurisdiction shall not affect the
validity or enforceability of any such provision in any other jurisdiction. Any
reference herein contained to a statute or law of a state in which no part of
the Mortgaged Property is situated shall be deemed inapplicable to, and not used
in, the interpretation hereof.

         6.8 Rights Cumulative. Each and every right, power and remedy herein
given to the Trustees or the Collateral Agent shall be cumulative and not
exclusive; and each and every right, power and remedy whether specifically
herein given or otherwise existing may be exercised from time to time and so
often and in such order as may be deemed expedient by the Trustees and the
Collateral Agent, as the case may be, and the exercise, or the beginning of the
exercise, of any such right, power or remedy shall not be deemed a waiver of the
right to exercise, at the same time or thereafter, any other right, power or
remedy. No delay or omission by the Trustees or the Collateral Agent or any of
them in the exercise of any right, power or remedy shall impair any such right,
power or remedy or operate as a waiver thereof or of any other right, power or
remedy then or thereafter existing. [In addition to all the rights and remedies
granted hereunder, the Mortgagor agrees to comply with all statutory mortgage
covenants and agree that this Mortgage shall be subject to the statutory
mortgage condition.](1)

         6.9 Waiver by the Trustees. Any and all covenants in this instrument
may from time to time by instrument in writing signed by the Trustees be waived
to such extent and in such manner as the Trustees may desire, but no such waiver
shall ever affect or impair either the Trustees' or the Collateral Agent's
rights or liens or security interests hereunder, except to the extent
specifically stated in such written instrument.

         6.10 Action by Individual Trustee. Any Trustee from time to time
serving hereunder shall have the absolute right, acting individually, to take
any action and to give any consent and to exercise any right, remedy, power,
privilege or authority conferred upon the Trustees, and any action taken by
either Trustee from time to time serving hereunder shall be binding upon the
other Trustee and no person dealing with either Trustee from time to time
serving hereunder shall be obligated to confirm the power and authority of such
Trustee to act without the concurrence of the other Trustee. In this instrument,
the term "Trustee" shall mean the Trustees hereinabove named, or either of them,
as the context requires, and any successor Trustee.

         6.11 Miscellaneous Warranties. The Mortgagor additionally warrants and
represents to the Trustees and the Collateral Agent that (a) the execution and
delivery of this instrument, and the 



- ----------------------

     (1)  To be used in Mortgages to be filed in New Mexico.

 

                               Exhibit R - Page 19

<PAGE>   58


performance by the Mortgagor of its obligations hereunder, are within the
corporate, partnership or other powers of the Mortgagor and have been duly
authorized by all necessary corporate, partnership or other action on the part
of the Mortgagor, and (b) this instrument has been duly executed and delivered
on behalf of the Mortgagor and is the legal, valid and binding obligation of the
Mortgagor, enforceable in accordance with its terms except as such
enforceability is subject to the effect of (i) any applicable bankruptcy,
insolvency, reorganization or similar laws relating to or affecting creditors'
rights generally and (ii) general principles of equity (regardless of whether
such enforceability is considered in a proceeding in equity or at law, including
without limitation, concepts of materiality, reasonableness, good faith and fair
dealing, and (c) the execution, delivery and performance of this instrument do
not and will not contravene or conflict with the organizational documents of the
Mortgagor or, to the best knowledge of the Mortgagor, violate or constitute a
default under any law, any presently existing requirement or restriction imposed
by judicial, arbitral or any governmental instrumentality.

         6.12 Successors and Assigns. This instrument is binding upon the
Mortgagor, the Mortgagor's successors and assigns, and shall inure to the
benefit of the Trustees, their successors, and the Collateral Agent, its
successors and assigns, and the provisions hereof shall likewise be covenants
running with the land.

         6.13 Article and Section Headings. The article and section headings in
this instrument are inserted for convenience of reference and shall not be
considered a part of this instrument or used in its interpretation.

         6.14 Execution in Counterparts. This instrument may be executed in any
number of counterparts, each of which shall for all purposes be deemed to be an
original and all of which are identical, except that, to facilitate recordation
or filing, in any particular counterpart portions of Exhibit A hereto which
describe properties situated in counties other than the county in which such
counterpart is to be recorded or filed may have been omitted.

         6.15 Special Filing as Financing Statement. This Mortgage and Deed of
Trust shall likewise be a Security Agreement and a Financing Statement. This
Mortgage and Deed of Trust shall be filed for record, among other places, in the
real estate records of each county in which any portion of the real property
covered by the oil and gas leases described in Exhibit A hereto is situated,
and, when filed in such counties shall be effective as a financing statement
covering fixtures located on oil and gas properties, which oil and gas
properties (and accounts arising therefrom) are to be financed at the wellheads
of the wells located on the real property described in Exhibit A hereto. At the
option of the Collateral Agent, a carbon, photographic or other reproduction of
this instrument or of any financing statement covering the Mortgaged Property or
any portion thereof shall be sufficient as a financing statement and may be
filed as such.

         6.16 Notices. Except as otherwise specifically provided for herein, all
notices, demands, instructions and other communications required or permitted to
be given to or made upon any party hereto shall be in writing and shall be
personally delivered or sent by certified mail, postage prepaid, return receipt
requested, or by telecopier, and shall be deemed to be given for purposes of
this instrument on the day that such writing is delivered or sent to the
intended recipient thereof in accordance with the provisions of this Section
6.16. Unless otherwise specified in a notice sent or delivered in accordance
with the foregoing 

 

                               Exhibit R - Page 20

<PAGE>   59


provisions of this Section 6.16, notices, demands, instructions and other
communications in writing shall be given to or made upon the respective parties
hereto at their respective addresses (or to their respective telecopier numbers)
indicated on the signature page(s) hereof.

         6.17 Release Upon Disposition; Termination.

         (a) From time to time during the term of this Agreement, unless an
event of default shall have occurred and be continuing, the Trustees and the
Collateral Agent shall execute, acknowledge and deliver to the Mortgagor a
release from this instrument of Mortgaged Properties in connection with the
sale, transfer or other disposition of such Mortgaged Properties by the
Mortgagor, other than a sale, transfer or disposition to Borrower or any
Subsidiary of Borrower and other than the mortgaging, pledging, securing or
granting of a lien, mortgage or security interest in the Mortgaged Properties to
any of them. Upon the receipt by the Collateral Agent of an Officer's
Certificate certifying that no event of default has occurred and is continuing
and that certain Mortgaged Properties described in such Officer's Certificate,
or an attachment thereto, are to be sold, transferred or disposed of by the
Mortgagor pursuant to a bona fide agreement, other than a sale, transfer or
disposition to Borrower or any Subsidiary of Borrower and other than the
mortgaging, pledging, securing or granting of a lien, mortgage or security
interest in the Mortgaged Properties to any of them, the Collateral Agent shall
execute, acknowledge and deliver to the Mortgagor an appropriate instrument
evidencing such release of such Mortgaged Property in such form as may be
reasonably requested by the Mortgagor. The Trustees shall execute, acknowledge
and deliver to the Mortgagor, and the purchaser or other transferee shall be to
rely conclusively on, any such instrument of release of Mortgaged Properties
which bears the signature of the Collateral Agent without any further inquiry.
It is expressly understood that any such release may be delivered to the
Mortgagor prior to the actual sale, transfer or disposition to facilitate such
transaction, provided that such release shall be canceled and redelivered to the
Collateral Agent if such Mortgaged Properties are not so sold, transferred or
disposed of within 20 days after the date such release has been fully executed,
acknowledged and delivered to the Mortgagor. As used herein, the term "Officer's
Certificate" means a certificate signed by the Chairman of the Board, the
President, any Executive Vice President, or the Chief Financial Officer of the
Mortgagor, and the term "Subsidiary" of Borrower means an entity of which more
than 50% of the securities entitled to normal voting power are owned directly,
or indirectly through one or more other Subsidiaries, by Borrower.

         (b) The Trustee and the Collateral Agent shall execute, acknowledge and
deliver to the Mortgagor a termination of this instrument and full release of
all the Mortgaged Properties upon receipt of a notice or other writing signed by
the Administrative Agent under the Primary Credit Agreement, stating that this
instrument is no longer required to be maintained pursuant to the terms of the
Primary Credit Agreement. Such termination of this instrument and full release
of all the Mortgaged Properties shall be evidenced by an instrument in such form
as may be reasonably requested by the Mortgagor, which will be executed,
acknowledged and delivered by the Trustees and the Collateral Agent with
reasonable promptness following receipt of such notice or other writing signed
by the Administrative Agent.

         [6.18 North Dakota Provisions. THE PARTIES AGREE THAT THIS MORTGAGE
CONSTITUTES A COLLATERAL REAL ESTATE MORTGAGE PURSUANT TO NORTH DAKOTA CENTURY
CODE CHAPTER 35-03.]


 

                               Exhibit R - Page 21

<PAGE>   60



         [6.19 New Mexico Mortgage. With respect to the Mortgaged Property
located in the State of New Mexico, this Mortgage shall be construed as a
Mortgage and will be subject to foreclosure by law upon, among others, the
occurrence of any event of default.](1)

- -----------------

     (1)  To be used in Mortgages to be filed in New Mexico.

 

                               Exhibit R - Page 22

<PAGE>   61



         IN WITNESS WHEREOF, the Mortgagor has executed or caused to be executed
this Mortgage, Deed of Trust, Assignment, Security Agreement and Financing
Statement on the day, month and year first above written.

                                       MORTGAGOR


                                       ----------------------------------------

                                       By:
                                          -------------------------------------
ATTEST:                                Title:
                                       Printed Name:


- --------------------
Secretary
Printed Name:





The name and mailing address of the Mortgagor is:



- ---------------------
c/o PIONEER NATURAL RESOURCES COMPANY
1400 Williams Square West
5205 North O'Connor Blvd.
Irving, Texas 75039





                       (Signatures Continued on Next Page)


 

                               Exhibit R - Page 23

<PAGE>   62



                                    SECURED PARTIES


                                    -------------------------------------------
                                                     , Trustee
                                    -----------------


                                    -------------------------------------------
                                                     , Trustee
                                    -----------------
                                                         , as Collateral Agent
                                    --------------------


                                    By:
                                       ----------------------------------------
ATTEST:                             Name:
                                    Printed Name:


- -----------------------
Title:
Printed Name:

The names and mailing addresses of the Secured Parties are:

________________________, as Collateral Agent
_____________, Trustee and __________, Trustee
_______________________________________
_______________________________________

This Instrument Was Prepared By:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, Texas  77002

[signature]

[SIGNED IN THE PRESENCE OF:


___________________
___________________]

 

                               Exhibit R - Page 24

<PAGE>   63



STATE OF TEXAS     )
                   ) Section.
COUNTY OF HARRIS   )


         BE IT REMEMBERED that I, _______, a Notary Public duly qualified,
commissioned, sworn and acting in and for the County and State aforesaid, hereby
certify that, on this day of ____, ______, there appeared before me severally
each of the following persons _____________, the ________, and _________, the
Secretary, of _______________________, a _____________, whose address is 1400
Williams Square West, 5205 North O'Connor Blvd., Irving, Texas 75039.


          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers with full authority, executed
                           the same voluntarily for and as the act of said
                           corporation.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation set forth opposite their names above and
                           were duly authorized in their respective capacities
                           to execute the foregoing instrument for and in the
                           name and on behalf of said corporation, and further
                           stated and acknowledged that they had so signed,
                           executed and delivered said foregoing instrument for
                           the consideration, uses and purposes therein
                           mentioned and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers of the corporation that executed the
                           above instrument on behalf of said corporation and
                           acknowledged to me that such corporation executed the
                           same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.


 

                               Exhibit R - Page 25

<PAGE>   64



KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation set opposite his name, on behalf of said
                           corporation.

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation set opposite their names
                           on behalf of said corporation.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their names of Pogo
                           Producing Company, a Delaware corporation, on behalf
                           of said corporation [in its capacity as general
                           partner of Pogo Gulf Coast, Ltd., a Texas limited
                           partnership, on behalf of said partnership].

NORTH
DAKOTA                     Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation set opposite their names which executed
                           the foregoing instrument, signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation as such officers, respectively; that the
                           same is their free act and deed as such officers,
                           respectively, and the free and corporate act and deed
                           of the corporation set opposite their names; that
                           they were duly authorized thereupon by the board of
                           directors of said corporation; and that (as the case
                           may be) the seal affixed to said instrument is the
                           corporate seal of said corporation.

OKLAHOMA                   Before me on this day personally appeared the
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation set opposite his name
                           for the uses and purposes therein set forth.


 

                               Exhibit R - Page 26

<PAGE>   65



SOUTH DAKOTA               Before me personally appeared each such person, who
                           acknowledged himself to be the designated officer of
                           the corporation set opposite his name, as the case
                           may be, and that as such designated officer being
                           authorized so to do, he executed the foregoing
                           instrument for the purposes therein contained, by
                           signing the name of said corporation by himself as
                           such designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation set opposite his name on behalf of
                           said corporation set opposite his name.

UTAH                       On this day personally appeared before me such
                           persons, who, being by me duly sworn, did say, that
                           they are the designated officers of said corporation,
                           and that said instrument was signed in behalf of said
                           corporation by resolution of its Board of Directors,
                           and said persons acknowledged to me that the said
                           corporation, executed the same.

WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.

         GIVEN under my hand and seal this ___ day of ____________.



                                              -----------------------
                                              Notary Public in and for
                                              Harris County, TEXAS


                                              -----------------------
                                              Print or Type Name


My commission expires:


 

                               Exhibit R - Page 27

<PAGE>   66



STATE OF ___    )
                ) Section.
COUNTY OF ___   )

         BE IT REMEMBERED that I, ________, a Notary Public duly qualified,
commissioned, sworn and acting in and for the County and State aforesaid, hereby
certify that, on this ____ day of ______, _____, there appeared before me
severally each of the following persons, each being either a Trustee or else the
designated officer of the corporation or association set opposite his name, and
each such Trustee, corporation or association being a party to the foregoing
instrument:

                  ___________, _____________and ______, _____of ____________, a
         ______________, whose address is _____________________;

                  ____________ and ________ whose addresses are ____________, as
         Trustees.

          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers or Trustees with full
                           authority, executed the same voluntarily for and as
                           the act of said corporation, said association or said
                           Trustees, as the case may be.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation or association set forth opposite their
                           names above (or, in the case of the Trustees, were
                           validly appointed Trustees) and were duly authorized
                           in their respective capacities to execute the
                           foregoing instrument for and in the name and on
                           behalf of said corporation or association (or as
                           Trustees, as the case may be), and further stated and
                           acknowledged that they had so signed, executed and
                           delivered said foregoing instrument for the
                           consideration, uses and purposes therein mentioned
                           and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation or association, or himself, as Trustee,
                           as the case may be.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers (or Trustees, as the case may be) of
                           the 
 

                               Exhibit R - Page 28

<PAGE>   67


                           corporation or the association that executed the
                           above instrument on behalf of said corporation or
                           association (or themselves, as Trustees) and
                           acknowledged to me that such corporation, association
                           or Trustees executed the same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.

KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation or association set opposite his name (or
                           a Trustee, as the case may be), on behalf of said
                           corporation or association (or of himself, as a
                           Trustee, as the case may be).

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation or association described in and that
                           executed the within instrument (or a Trustee, as the
                           case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation or association set
                           opposite their names (or as Trustees, as the case may
                           be) on behalf of said corporation or association, or
                           himself as a Trustee, as the case may be.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their names, of ______, a
                           _____ on behalf of said ______ [(or individually as
                           trustees, residing at ________ as the case may be, on
                           behalf of himself, as a Trustee)] [(or as the
                           designated officer of the Trustee set opposite their
                           respective names, of ______, a ________, and
                           _________, a ________, respectively on behalf of said
                           corporation or association, as trustee)].(1)




- --------------
     (1)  Modify as necessary for individual or corporate trustees.

 

                               Exhibit R - Page 29

<PAGE>   68



NORTH DAKOTA               Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation or association described in and that
                           executed the within instrument (or a Trustee, as the
                           case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation or association set opposite their names
                           which executed the foregoing instrument (or as
                           Trustees, as the case may be), signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation or association as such officers,
                           respectively (or as Trustees, as the case may be);
                           that the same is their free act and deed as such
                           officers, respectively (or as Trustees as the case
                           may be), and (as the case may be) the free and
                           corporate act and deed of the corporation or
                           association set opposite their names; that (as the
                           case may be) they were duly authorized thereunto by
                           the board of directors of said corporation or
                           association; and that (as the case may be) the seal
                           affixed to said instrument is the corporate seal of
                           said corporation or association.

OKLAHOMA                   Before me on this day personally appeared the
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation or association set
                           opposite his name (or of himself as Trustee, as the
                           case may be) for the uses and purposes therein set
                           forth.

SOUTH DAKOTA               Before me personally appeared each such person, who
                           acknowledged himself to be the designated officer of
                           the corporation or association set opposite his name,
                           or a Trustee, as the case may be, and that (as the
                           case may be, as such designated officer being
                           authorized so to do) he executed the foregoing
                           instrument for the purposes therein contained, by (as
                           the case may be) signing the name of said corporation
                           or association by himself as such designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation or association set opposite his name
                           (or a Trustee, as the case may be), on behalf of said
                           corporation or association set opposite his name (or
                           of himself as Trustee, as the case may be).

UTAH                       On this day personally appeared before me such
                           persons, who, being by me duly sworn, did say, that
                           (as the case may be) they are the designated officers
                           of said corporation or association or are Trustees
                           and that said instrument was signed (as the case may
                           be) in behalf of said corporation or association by
                           resolution of its Board of Directors (or on behalf of
                           themselves as Trustees, as the case may be), and said
                           persons acknowledged to me that said corporation,
                           association or Trustees executed the same.


 

                               Exhibit R - Page 30

<PAGE>   69



WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.

              GIVEN under my hand and seal this ____ day of _____________.



                                         ----------------------
                                         Notary Public in and for
                                                  County,
                                         ---------       ------
                                    

                                         ----------------------
                                         Print or Type Name

My commission expires:


 



                               Exhibit R - Page 31

<PAGE>   70



                                        
               EXHIBIT A To Mortgage, Deed of Trust, Assignment,
               Security Agreement and Financing Statement, dated
                   _________,______, from __________________
                        to _______________ and _________
                            and ___________________,
                              as Collateral Agent
                                        
                               List of Properties
                                        
                       [to be prepared by the Mortgagor]


         1. Depth limitations, unit designations, unit tract descriptions and
descriptions of undivided leasehold interests, well names, "Operating
Interests", "Working Interests" and "Net Revenue Interests" contained in this
Exhibit A and the listing of any percentage, decimal or fractional interest in
this Exhibit A shall not be deemed to limit or otherwise diminish the interests
being subjected to the lien, security interest and encumbrance of this
instrument.

         2. Some of the land descriptions in this Exhibit A may refer only to a
portion of the land covered by a particular lease. This instrument is not
limited to the land described in Exhibit A but is intended to cover the entire
interest of the Mortgagor in any lease described in Exhibit A even if such
interest relates to land not described in Exhibit A. Reference is made to the
land descriptions contained in the documents of title recorded as described in
this Exhibit A. To the extent that the land descriptions in this Exhibit A are
incomplete, incorrect or not legally sufficient, the land descriptions contained
in the documents so recorded are incorporated herein by this reference.

         3. References in Exhibit A to instruments on file in the public records
are made for all purposes. Unless provided otherwise, all recording references
in Exhibit A are to the official real property records of the county or counties
(or parish or parishes) in which the mortgaged property is located and in which
records such documents are or in the past have been customarily recorded,
whether Deed Records, Oil and Gas Records, Oil and Gas Lease Records or other
records.

         4. A statement herein that a certain interest described herein is
subject to the terms of certain described or referred to agreements, instruments
or other matters shall not operate to subject such interest to any such
agreement, instrument or other matter except to the extent that such agreement,
instrument or matter is otherwise valid and presently subsisting nor shall such
statement be deemed to constitute a recognition by the parties hereto that any
such agreement, instrument or other matter is valid and presently subsisting.



 

                               Exhibit R - Page 32

<PAGE>   71



                                   Schedule 1

              Schedule of Lenders' Commitments and Percentage Share

<TABLE>
<CAPTION>
             Lenders                                  Commitment             Percentage Share
           -----------                            --------------------     --------------------
<S>                                              <C>                      <C>          

NationsBank, N.A                                  $      13,558,994.18             15.866908084%

CIBC Inc.                                         $       8,104,448.75              9.483929389%

Morgan Guaranty Trust Company of New              $       8,104,448.75              9.483929389%
York

Chase Bank of Texas, National                     $       8,104,448.75              9.483929389%
Association

The Bank of New York                              $       5,454,545.45              6.382978718%

The Bank of Nova Scotia                           $       5,454,545.45              6.382978718%

Royal Bank of Canada                              $       5,454,545.45              6.382978718%

Union Bank of California, N.A                     $       5,454,545.45              6.382978718%

Wells Fargo Bank, N.A                             $       5,454,545.45              6.382978718%

Bank One, Texas, N.A                              $       2,127,659.57              2.489814391%

Den Norske Bank ASA                               $       3,636,363.64              4.255319153%

Paribas                                           $       3,636,363.64              4.255319153%

First Union National Bank                         $       3,636,363.64              4.255319153%

Bankers Trust Company                             $       1,818,181.82              2.127659577%

Credit Agricole Indosuez                          $       1,818,181.82              2.127659577%

Natexis Banque                                    $       1,818,181.82              2.127659577%

Toronto Dominion (Texas), Inc.                    $       1,818,181.82              2.127659577%


                                                  ====================     ====================
Totals:                                           $      85,454,545.45             100.00000000%
</TABLE>


 

                               Schedule 1 - Page 1

<PAGE>   72



                                   Schedule 3

                       Schedule of Restricted Subsidiaries

         This Schedule 3 is attached to and made a part of (i) that certain
Primary Credit Facility pursuant to that certain Second Amended and Restated
Credit Facility Agreement dated as of March 19, 1999 by and among Borrower,
NationsBank, N.A., as Administrative Agent, CIBC Inc., as Documentation Agent,
Morgan Guaranty Trust Company of New York, as Documentation Agent, Chase Bank of
Texas, National Association, as successor-in-interest to The Chase Manhattan
Bank, as Syndication Agent, the Co-Agents party thereto, and the Lenders from
time to time parties thereto, and (ii) that certain 364 Day Credit Facility
pursuant to that certain Second Amended and Restated Credit Facility Agreement
dated as of March 19, 1999 by and among Borrower, NationsBank, N.A., as
Administrative Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust
Company of New York, as Documentation Agent, Chase Bank of Texas, National
Association, as successor-in-interest to The Chase Manhattan Bank, as
Syndication Agent, the Co-Agents party thereto, and the Lenders from time to
time parties thereto.

Pioneer Natural Resources USA, Inc., a Delaware corporation
Pioneer International Resources Company, a Delaware corporation
Pioneer Resources Producing L.P., a Delaware limited partnership
Parker & Parsley (Canada) Petroleum Company, a Nova Scotia, Canada limited 
  liability company 
Pioneer Resources, Inc., , a Delaware corporation 
P&PCanada LP Co., a Delaware corporation 
Pioneer Natural Resources Canada, Inc., an Alberta, Canada limited liability 
  company 
Pioneer Natural Resources (Argentina) S.A., an Argentina limited liability 
  company 
Pioneer Natural Resources (Tierra del Fuego) S.A., an Argentina limited 
  liability company 
Westpan NGL Co., a Delaware corporation 
Pioneer Natural Resources (Cayman) Ltd., a Cayman exempted company
Parker & Parsley Petroleum Australia Holdings Pty Limited (A.C.N. 064 589 242),
  a New South Wales, Australia corporation
Parker & Parsley Petroleum Australia Pty Limited (A.C.N. 064 589 180), a New 
  South Wales, Australia corporation
Bridge Oil (U.S.A.) Inc., a Delaware corporation


 

                               Schedule 3 - Page 1

<PAGE>   73



                                   Schedule 4

                              Schedule of Insurance





 

                               Schedule 4 - Page 2

<PAGE>   74


                                   Schedule 5

                        Schedule of Security Instruments

Guaranties   -  Pioneer Natural Resources USA, Inc., a Delaware corporation
                Pioneer International Resources Company, a Delaware corporation
                Pioneer Resources Producing L.P., a Delaware limited partnership
                Pioneer Resources, Inc., a Delaware corporation
                P&PCanada LP Co., a Delaware corporation
                Pioneer Natural Resources Canada Inc., an Alberta, Canada 
                  corporation
                Westpan NGL Co., a Delaware corporation
                Pioneer Natural Resources (Argentina) S.A., an Argentina 
                  limited liability company
                Pioneer Natural Resources (Tierra del Fuego) S.A., an Argentina
                  limited liability company

Pledge Agreements or Deeds of Mortgage, Blank Stock Powers and Financing
Statements:

         Pledge A4greement by Pioneer Resources, Inc., a Delaware corporation,
         covering shares of Parker & Parsley (Canada) Petroleum Company, a Nova
         Scotia, Canada limited liability company

         Pledge Agreement by P&PCanada LP Co., a Delaware corporation, covering
         shares of Parker & Parsley (Canada) Petroleum Company, a Nova Scotia,
         Canada limited liability company

         Deed of Mortgage by Pioneer Natural Resources Company USA, Inc., a
         Delaware corporation, covering shares of Parker & Parsley Petroleum
         Australia Holdings Pty. Limited (A.C.N. 064 589 242), a New South
         Wales, Australia corporation

         Pledge Agreement by Pioneer International Resources Company, a Delaware
         corporation, covering shares of Pioneer Natural Resources Canada Inc.,
         an Alberta, Canada limited liability company

         Pledge Agreement by Pioneer Natural Resources USA, Inc., a Delaware
         corporation, covering shares of Pioneer Natural Resources (Cayman)
         Ltd., a Cayman exempted company





                               Schedule 5 - Page 1





<PAGE>   1
                                                                    EXHIBIT 11.1

                        PIONEER NATURAL RESOURCES COMPANY

                 STATEMENT OF COMPUTATION OF EARNINGS PER SHARE

<TABLE>
<CAPTION>
                                                                                               Per Share
                                                              Income            Shares         Amount(a)
                                                            -----------         -------        ---------
                                                                    (in thousands)
<S>                                                         <C>                 <C>            <C>
DECEMBER 31, 1998

Basic EPS:
  Loss available to common stockholders                     $  (746,426)        100,055        $   (7.46)
                                                                                               =========

Effect of Dilutive Securities                                        --              --
                                                            -----------         -------

Diluted EPS:
  Loss available to common stockholders plus
    assumed dilutive conversions                            $  (746,426)        100,055        $   (7.46)
                                                            ===========         =======        =========



DECEMBER 31, 1997

Basic EPS:
  Loss available to common stockholders                     $  (890,671)         51,973        $  (17.14)
                                                                                               =========

Effect of Dilutive Securities                                        --              --
                                                            -----------         -------

Diluted EPS:
  Loss available to common stockholders plus
    assumed dilutive conversions                            $  (890,671)         51,973        $  (17.14)
                                                            ===========         =======        =========



DECEMBER 31, 1996

Basic EPS:
  Income available to common stockholders                   $  140,248           35,475        $    3.95
                                                                                               =========

Effect of Dilutive Securities:
  Options/restricted stock                                          --              394
  Preferred shares                                               7,683            6,714
                                                            ----------          -------

Diluted EPS:
  Income available to common stockholders plus
    assumed conversions                                     $  147,931           42,583        $    3.47
                                                            ==========          =======        =========
</TABLE>


- -----------

(a) For 1998 and 1997, the computation of diluted net loss per share was
    antidilutive; therefore, the amounts reported for basic and diluted net loss
    per share were the same.

<PAGE>   1
                                                                    EXHIBIT 21.1


                           SUBSIDIARIES OF THE COMPANY

<TABLE>
<CAPTION>
State or Jurisdiction
   of Organization                    Subsidiaries
- ---------------------                 ------------

<S>                                   <C>
Australia                             Antenor P/L
Switzerland                           Aredor Distribution Company Ltd.
Australia                             Aredor Holdings Ltd.
Australia                             Bridge Oil Australia Pty Ltd.
Australia                             Bridge Oil Services (Overseas) P/L
Delaware                              Bridge Oil (U.S.A.) Inc.
Australia                             Bridge Oil ZOCA 91-13 P/L
Bermuda                               CR International Limited
Delaware                              DMLP Co.
Delaware                              Doram Energy, Inc.
Texas                                 Dorchester Gas Systems, Inc.
Texas                                 Dorchester Intrastate Gas Systems, L.P.
Delaware                              Mesa Environmental Ventures Co.
Texas                                 Mesa Offshore Royalty Partnership
Delaware                              P&PCanada LP Co.
Delaware                              Parker & Parsley Argentina, Inc.
Canada                                Parker & Parsley (Canada) Petroleum Company
Turks and Caicos Islands              Parker & Parsley Capital LLC
Cayman Islands                        Parker & Parsley International Holdings, Ltd.
Australia                             Parker & Parsley Petroleum Australia Holdings Pty Limited
Australia                             Parker & Parsley Petroleum Australia Pty Limited
Texas                                 Pioneer Natural Resources Scholarship Foundation
New York                              Parker & Parsley Transfer Agent Corporation
Delaware                              Pioneer Holding Inc.
Delaware                              Pioneer International Resources Company
Texas                                 Pioneer Natural Gas Company
Argentina                             Pioneer Natural Resources (Argentina) S.A.
Canada                                Pioneer Natural Resources Canada Inc.
Cayman Islands                        Pioneer Natural Resources (Cayman) Ltd.
Cayman Islands                        Pioneer Natural Resources Guatemala Ltd.
Canada                                Pioneer Natural Resources (ND) Holdings Inc.
South Africa                          Pioneer Natural Resources South Africa (Pty) Limited
Argentina                             Pioneer Natural Resources (Tierra Del Fuego) S.A.
Delaware                              Pioneer Natural Resources USA, Inc.
Delaware                              Pioneer NGLs (USA) Inc.
Delaware                              Pioneer Pipelines (USA) Inc.
Delaware                              Pioneer Resources Inc.
Bahamas                               Pioneer Resources Africa, Ltd.
Delaware                              Pioneer Resources China, Inc.
Bahamas                               Pioneer Resources Gabon - Olowi Ltd.
Delaware                              Pioneer Resources (ND) Inc.
Delaware                              Pioneer Resources Producing L.P.
Texas                                 Pioneer Uravan, Inc.
Delaware                              PNR Resources (USA) Inc.
Texas                                 PNRC Properties L.P.
Delaware                              Rosamond Drilling Company, Inc.
Delaware                              Westpan NGL Co.
</TABLE>



<PAGE>   2


<TABLE>
<CAPTION>
State or Jurisdiction
   of Organization                    Subsidiaries
- ---------------------                 ------------

<S>                                   <C>
Partnerships that Pioneer Natural Resources USA, Inc. is the managing general partner
- -------------------------------------------------------------------------------------

Texas                                 Parker & Parsley 81-I, Ltd.
Texas                                 Parker & Parsley 81-II, Ltd.
Texas                                 Parker & Parsley 82-I, Ltd.
Texas                                 Parker & Parsley 82-II, Ltd.
Texas                                 Parker & Parsley 82-III, Ltd.
Texas                                 Parker & Parsley 83-A, Ltd.
Texas                                 Parker & Parsley 83-B, Ltd.
Texas                                 Parker & Parsley 84-A, Ltd.
Texas                                 Parker & Parsley 85-A, Ltd.
Texas                                 Parker & Parsley 85-B, Ltd.
Texas                                 Parker & Parsley Private Investment 85-A Ltd.
Texas                                 Parker & Parsley Selected 85 Private Investment, Ltd.
Texas                                 Parker & Parsley 86-A, Ltd.
Texas                                 Parker & Parsley 86-B, Ltd.
Texas                                 Parker & Parsley 86-C, Ltd.
Texas                                 Parker & Parsley Private Investment 86, Ltd.
Delaware                              Parker & Parsley 87-A, Ltd.
Delaware                              Parker & Parsley 87-B, Ltd.
Delaware                              Parker & Parsley 87-A Conv., Ltd.
Delaware                              Parker & Parsley 87-B Conv., Ltd.
Delaware                              Parker & Parsley Private Investment 87, Ltd.
Delaware                              Parker & Parsley Producing Properties 87-A, Ltd.
Delaware                              Parker & Parsley Producing Properties 87-B, Ltd.
Delaware                              Parker & Parsley 88-A, L.P.
Delaware                              Parker & Parsley 88-B, L.P.
Delaware                              Parker & Parsley 88-C, L.P.
Delaware                              Parker & Parsley 88-A Conv., L.P.
Delaware                              Parker & Parsley 88-B Conv., L.P.
Delaware                              Parker & Parsley 88-C Conv., L.P.
Delaware                              Parker & Parsley Private Investment 88, L.P.
Delaware                              Parker & Parsley Producing Properties 88-A, L.P.
Delaware                              Parker & Parsley 89-A, L.P.
Delaware                              Parker & Parsley 89-B, L.P.
Texas                                 Parker & Parsley 89-A Conv., L.P.
Texas                                 Parker & Parsley 89-B Conv., L.P.
Texas                                 P&P Employees 89-A Conv., L.P.
Texas                                 P&P Employees 89-B Conv., L.P.
Delaware                              Parker & Parsley Private Investment 89, L.P.
Texas                                 P&P Employees Private Investment 89, L.P.
Delaware                              Parker & Parsley 90-A Conv., L.P.
Delaware                              Parker & Parsley 90-B Conv., L.P.
Delaware                              Parker & Parsley 90-C Conv., L.P.
Delaware                              Parker & Parsley 90-A, L.P.
Delaware                              Parker & Parsley 90-B, L.P.
Delaware                              Parker & Parsley 90-C, L.P.
Texas                                 P&P Employees 90-A Conv., L.P.
Texas                                 P&P Employees 90-B Conv., L.P.
Texas                                 P&P Employees 90-C Conv., L.P.
Delaware                              Parker & Parsley Private Investment 90 Conv., L.P.
Texas                                 P&P Employees Private Investment 90 Conv., L.P.
Delaware                              Parker & Parsley 90 Spraberry Private Development Conv., L.P.
Texas                                 P&P Employees 90 Spraberry Private Development L.P.
Delaware                              Parker & Parsley 91-A, L.P.
Delaware                              Parker & Parsley 91-B, L.P.
Delaware                              Parker & Parsley 91-A Conv., L.P.
</TABLE>


<PAGE>   3

<TABLE>
<CAPTION>
State or Jurisdiction
   of Organization                    Subsidiaries
- ---------------------                 ------------

<S>                                   <C>
Delaware                              Parker & Parsley 91-B Conv., L.P.
Texas                                 P&P Employees 91-A G.P.
Texas                                 P&P Employees 91-B G.P.
Texas                                 Parker & Parsley 1992 Direct Investment Program, Ltd.
Texas                                 Parker & Parsley 1993 Direct Investment Program, Ltd.
Texas                                 Parker & Parsley 1994 Direct Investment Program, Ltd.
Texas                                 Midkiff Development Drilling Program, Ltd.
</TABLE>



<PAGE>   1
EXHIBIT 23.1


                        CONSENT OF INDEPENDENT AUDITORS


We consent to the incorporation by reference in the Registration Statements (No.
333-35087, No. 333-35165, No. 333-39153, No. 333-39249, No. 33-44851, No.
333-35085 and No. 333-35175) on Form S-8 and (No. 333-42315, No. 333-44439 and
No. 333-39381) on Form S-3 of Pioneer Natural Resources Company and subsidiaries
of our report dated February 2, 1999, with respect to the consolidated financial
statements of Pioneer Natural Resources Company included in this Annual Report
on Form 10-K for the year ended December 31, 1998.


                                                  /s/ Ernst & Young LLP



Dallas, Texas
March 23, 1999



<PAGE>   1
                                                                    EXHIBIT 23.2


                        CONSENT OF INDEPENDENT AUDITORS


The Board of Directors and Stockholders
Pioneer Natural Resources Company:

     We consent to the incorporation by reference in the Registration Statements
(No. 333-35087, No. 333-35165, No. 333-39153, No. 333-39249, No. 33-44851, No.
333-35085 and No. 333-35175) on Form S-8 and Registration Statements (No.
333-42315, No. 333-44439 and No. 333-39381) on Form S-3 of Pioneer Natural
Resources Company and subsidiaries and its predecessors of our report dated
February 13, 1998, relating to the consolidated balance sheet of Pioneer
Natural Resources Company and subsidiaries as of December 31, 1997 and the
related consolidated statements of operations and comprehensive income,
stockholders' equity, and cash flows for the years ended December 31, 1997 and
1996, which report appears in the December 31, 1998 annual report on Form 10-K
of Pioneer Natural Resources Company. 





                                                                KPMG LLP

Midland, Texas
March 23, 1999

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