<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
COMPANY'S FINANCIAL STATEMENTS AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS.
</LEGEND>
<RESTATED>
       
                                                                                                   
<PERIOD-TYPE>                          3-MOS                   6-MOS                   9-MOS                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997             DEC-31-1997
<CASH>                                          39,258                  41,145                  70,860                 102,958
<SECURITIES>                                   213,465                 196,624                 312,305                 363,137
<RECEIVABLES>                                  180,318                 197,092                 217,236                 205,589
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                     30,754                  31,282                  32,314                  33,714
<CURRENT-ASSETS>                               480,668                 482,128                 654,435                 718,775
<PP&E>                                       1,544,633               1,705,878               1,764,091               1,821,906
<DEPRECIATION>                                 297,072                 322,485                 349,381                 370,165
<TOTAL-ASSETS>                               1,963,759               2,124,664               2,201,527               2,298,561
<CURRENT-LIABILITIES>                          108,532                 115,672                 113,123                 131,145
<BONDS>                                        400,000                 400,000                 400,000                 400,000
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                           684                     696                   1,393                   1,393
<OTHER-SE>                                   1,249,900               1,398,374               1,464,198               1,534,134
<TOTAL-LIABILITY-AND-EQUITY>                 1,963,759               2,124,664               2,201,527               2,298,561
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                               204,733                 433,267                 683,764                 956,093
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                   89,739<F1>             187,960<F1>             287,867<F1>             406,343<F1>
<OTHER-EXPENSES>                                30,688<F2>              62,772<F2>              96,349<F2>             129,877<F2>
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                                   0                   3,349                   6,940                  10,270
<INCOME-PRETAX>                                 87,014                 187,403                 306,741                 430,061
<INCOME-TAX>                                    30,784                  65,939                 107,446                 151,456
<INCOME-CONTINUING>                             56,230                 121,464                 199,295                 278,605
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                    56,230                 121,464                 199,295                 278,605
<EPS-PRIMARY>                                     0.41<F3>                0.88<F3>                1.44<F3>                2.01<F3>
<EPS-DILUTED>                                     0.39<F3>                0.85<F3>                1.39<F3>                1.93<F3>
<FN>
<F1>Includes contract drilling expenses only.
<F2>Includes other operating expenses.
<F3>Per share amounts reflect the retroactive effect of the two-for-one stock
split in the form of a stock dividend to stockholders of record on July 24,
1997.
</FN>