<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FORM 10-Q
QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITY EXCHANGE ACT OF
1934 FOR THE QUARTERLY PERIOD ENDED JUNE 30, 1997 AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997
<PERIOD-START>                             APR-01-1997             JAN-01-1997
<PERIOD-END>                               JUN-30-1997             JUN-30-1997
<CASH>                                          18,622                  18,622
<SECURITIES>                                         0                       0
<RECEIVABLES>                                    5,085                   5,085
<ALLOWANCES>                                      (50)                    (50)
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                                24,009                  24,009
<PP&E>                                         201,090                 201,090
<DEPRECIATION>                                (95,097)                (95,097)
<TOTAL-ASSETS>                                 131,491                 131,491
<CURRENT-LIABILITIES>                           13,065                  13,065
<BONDS>                                              0                       0
<PREFERRED-MANDATORY>                                0                       0
<PREFERRED>                                          0                       0
<COMMON>                                            86                      86
<OTHER-SE>                                      66,637                  66,637
<TOTAL-LIABILITY-AND-EQUITY>                   131,491                 131,491
<SALES>                                          7,166                  16,141
<TOTAL-REVENUES>                                 7,586                  16,980
<CGS>                                                0                       0
<TOTAL-COSTS>                                    7,185                  14,222
<OTHER-EXPENSES>                                   (5)                       2
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                                 796                   1,590
<INCOME-PRETAX>                                  (258)                   1,454
<INCOME-TAX>                                     (502)                     235
<INCOME-CONTINUING>                                  0                       0
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                       244                   1,219
<EPS-PRIMARY>                                      .03                     .14
<EPS-DILUTED>                                      .03                     .14
        

</TABLE>