<ARTICLE>                                              5
<MULTIPLIER>                                       1,000
       
                                                
<PERIOD-TYPE>                                      9-MOS
<FISCAL-YEAR-END>                            Dec-31-1997
<PERIOD-END>                                 Sep-30-1997
<CASH>                                            19,445
<SECURITIES>                                           0
<RECEIVABLES>                                    152,499
<ALLOWANCES>                                       3,581
<INVENTORY>                                       10,665
<CURRENT-ASSETS>                                 183,372
<PP&E>                                         2,034,517
<DEPRECIATION>                                 1,137,431
<TOTAL-ASSETS>                                 1,175,730
<CURRENT-LIABILITIES>                            271,357
<BONDS>                                          198,766
<PREFERRED-MANDATORY>                                  0
<PREFERRED>                                            0
<COMMON>                                          72,530
<OTHER-SE>                                       467,126
<TOTAL-LIABILITY-AND-EQUITY>                   1,175,730
<SALES>                                                0
<TOTAL-REVENUES>                                 639,301
<CGS>                                                  0
<TOTAL-COSTS>                                    374,560
<OTHER-EXPENSES>                                       0
<LOSS-PROVISION>                                       0
<INTEREST-EXPENSE>                                16,717
<INCOME-PRETAX>                                  154,223
<INCOME-TAX>                                      57,321
<INCOME-CONTINUING>                               96,902
<DISCONTINUED>                                         0
<EXTRAORDINARY>                                        0
<CHANGES>                                              0
<NET-INCOME>                                      96,902
<EPS-PRIMARY>                                       0.00
<EPS-DILUTED>                                       0.00