LTIP PERFORMANCE UNIT AWARD PROGRAM
                               SUMMARY TERM SHEET


o    Parent company officers and selected subsidiary level officers will receive
     a portion of their awards under the Company's 2006 Long-Term Incentive Plan
     (the "LTIP") in the form of performance  units having a performance  period
     of three years,  and a portion of their awards under the LTIP in restricted
     stock.

o    Payments in respect of earned  performance  units will be made in shares of
     the Company's common stock.

o    LTIP awards made in the first quarter of 2007 will be allocated as follows:

                                          % Performance       % Restricted
Officer Description                            Units              Stock
-------------------                       -------------       ------------

Parent Company Officers                         50%                50%
Selected Subsidiary Company Officers            25%                75%


o    The terms of the restricted  stock grants made in the first quarter of 2007
     are expected to be similar to the terms of restricted  stock grants made to
     officers in prior years.

o    The following  terms relate to awards of  performance  units under the 2007
     Performance Unit Award Program (the "2007 Program"):

     o    The performance  metric  under the  2007  Program  will  be  based  on
          relative  Total Shareholder Return ("TSR"),  which means a  comparison
          among the Company  and each peer  company selected by the Compensation
          and Management Development Committee  of the annualized rate of return
          that each company's shareholders  receive through stock  price changes
          and  the  assumed  reinvestment  of all  dividends  over a  three-year
          performance period.

     o    TSR will be determined by  comparing the  change in the stock price at
          the beginning  of the three-year  performance period,  measured as the
          average closing price for the 60 calendar days before January 1, 2007,
          to the stock  price at the  end of the  three-year performance period,
          measured by the average closing price for  the 60 calendar days on and
          before December 31, 2009.  In the event of a change  in control of the
          Company  (a "CIC"),  the stock  price at  the end  of the  abbreviated
          performance period  will be measured by  the average closing price for
          the 60 calendar days prior to closing date of the CIC transaction.

     o    Refer to the  following TSR performance award  table for the levels of
          stock earned as a percentage  of the performance  unit target based on






          the Company's TSR during the three-year performance period as compared
          to that of a group of peer  companies selected by the Compensation and
          Management Development Committee.

     o    A separate performance  table is provided if the peer group is reduced
          to eleven, ten, nine or eight peers  (inclusive of the Company) due to
          a peer company no longer being publicly traded.  Should the peer group
          reduce to seven  or fewer companies,  the Compensation and  Management
          Development Committee  has the discretion to add companies to the peer
          group.



                       12 Co.      11 Co.      10 Co.      9 Co.       8 Co.
          Rank         Payout      Payout      Payout      Payout      Payout
          Against      % of        % of        % of        % of        % of
          Peers        Target      Target      Target      Target      Target
          -----        ------      ------      ------      ------      ------
                                                     
          1            250%        250%        250%        250%        250%
          2            200%        200%        200%        200%        200%
          3            175%        175%        170%        166%        155%
          4            150%        150%        140%        133%        110%
          5            125%        125%        110%        100%         70%
          6            110%        100%         80%         65%         30%
          7             75%         75%         50%         30%          0%
          8             50%         50%         25%          0%          0%
          9             25%         25%          0%          0%
          10             0%          0%          0%
          11             0%          0%
          12             0%


     o    Dividends  will be paid in shares  at the time of the payout of earned
          performance units and calculated based on the  number of shares earned
          times the aggregate  dividends per share  paid during  the performance
          period.

     o    In the event of a CIC, vesting of all units will accelerate and payout
          will be  measured by the relative  TSR for the abbreviated performance
          period.

     o    The effect of a  participant's termination of employment,  retirement,
          death or disability will be described in  the form of performance unit
          award agreement  to be approved  by the  Compensation  and  Management
          Development Committee  at or prior  to the grant of  performance units
          under the 2007 Program.

o    The peer group for the 2007 Program consists of the following companies:

XTO Energy Inc.                                Chesapeake Energy Corporation
Apache Corporation                             Quicksilver Resources Inc.
EOG Resources, Inc.                            Noble Energy, Inc.
Plains Exploration and Production Company      Cimarex Energy Co.
Pogo Producing Company                         Newfield Exploration Company
Range Resources Corporation