<ARTICLE> 5 <MULTIPLIER> 1,000 <CURRENCY> U.S. DOLLARS <PERIOD-TYPE> 9-MOS <FISCAL-YEAR-END> DEC-31-1997 <PERIOD-START> JAN-01-1997 <PERIOD-END> SEP-30-1997 <EXCHANGE-RATE> 1 <CASH> 18,766 <SECURITIES> 0 <RECEIVABLES> 22,325 <ALLOWANCES> 0 <INVENTORY> 0 <CURRENT-ASSETS> 41,525 <PP&E> 254,854 <DEPRECIATION> 120,679 <TOTAL-ASSETS> 198,414 <CURRENT-LIABILITIES> 25,973 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 110 <OTHER-SE> 146,805 <TOTAL-LIABILITY-AND-EQUITY> 198,414 <SALES> 54,025 <TOTAL-REVENUES> 69,186 <CGS> 11,042 <TOTAL-COSTS> 11,042 <OTHER-EXPENSES> 105 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 859 <INCOME-PRETAX> 32,965 <INCOME-TAX> 11,718 <INCOME-CONTINUING> 21,247 <DISCONTINUED> 296 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 21,543 <EPS-PRIMARY> 2.03 <EPS-DILUTED> 2.03