<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FORM 10-Q AS
OF SEPTEMBER 30, 1996 AND QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS
</LEGEND>
<MULTIPLIER> 1,000
       
                                                  
<PERIOD-TYPE>                   3-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1996             DEC-31-1996
<PERIOD-START>                             JUL-01-1996             JAN-01-1996
<PERIOD-END>                               SEP-30-1996             SEP-30-1996
<CASH>                                               0                       0
<SECURITIES>                                         0                       0
<RECEIVABLES>                                   88,853<F1>              88,853<F1>
<ALLOWANCES>                                         0                       0
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                               128,544                 128,544
<PP&E>                                         576,535                 576,535
<DEPRECIATION>                               (196,927)               (196,927)
<TOTAL-ASSETS>                                 897,934                 897,934
<CURRENT-LIABILITIES>                          189,794                 189,794
<BONDS>                                              0                       0
<PREFERRED-MANDATORY>                                0                       0
<PREFERRED>                                          0                       0
<COMMON>                                           772                     772
<OTHER-SE>                                     403,817                 403,817
<TOTAL-LIABILITY-AND-EQUITY>                   897,934                 897,934
<SALES>                                              0                       0
<TOTAL-REVENUES>                               289,195                 809,173
<CGS>                                                0                       0
<TOTAL-COSTS>                                  166,575                 472,828
<OTHER-EXPENSES>                                84,010                 231,889
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                               7,746                  22,908
<INCOME-PRETAX>                                 30,864                  81,548
<INCOME-TAX>                                    10,802                  28,542
<INCOME-CONTINUING>                             20,062                  53,006
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                    20,062                  53,006
<EPS-PRIMARY>                                     0.23                    0.61
<EPS-DILUTED>                                     0.23                    0.61
<FN>
<F1>TRADE ACCOUNTS RECEIVABLE; LESS ALLOWANCE FOR DOUBTFUL ACCOUNTS
</FN>