<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
ACCOMPANYING FINANCIAL STATEMENTS AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE
TO SUCH FINANCIAL STATEMENTS.
*** (COLUMNAR AMOUNTS IN THOUSANDS, EXCEPT PER SHARE DATA) ***
</LEGEND>
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-END>                               JUN-30-1997
<CASH>                                          11,441
<SECURITIES>                                         0
<RECEIVABLES>                                   56,092
<ALLOWANCES>                                         0
<INVENTORY>                                      9,427
<CURRENT-ASSETS>                                83,155
<PP&E>                                         376,193
<DEPRECIATION>                                 124,058
<TOTAL-ASSETS>                                 376,782
<CURRENT-LIABILITIES>                           60,807
<BONDS>                                        104,173
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           123
<OTHER-SE>                                     167,826
<TOTAL-LIABILITY-AND-EQUITY>                   376,872
<SALES>                                         95,448
<TOTAL-REVENUES>                                95,448
<CGS>                                           73,479
<TOTAL-COSTS>                                   73,479
<OTHER-EXPENSES>                                 4,956
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               5,317
<INCOME-PRETAX>                                 11,854
<INCOME-TAX>                                    (6,612)
<INCOME-CONTINUING>                             18,158
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    18,158
<EPS-PRIMARY>                                     1.48
<EPS-DILUTED>                                     1.48