<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>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               JUN-30-1997
<CASH>                                          41,145
<SECURITIES>                                   196,624
<RECEIVABLES>                                  197,092
<ALLOWANCES>                                         0
<INVENTORY>                                     31,282
<CURRENT-ASSETS>                               482,128
<PP&E>                                       1,705,878
<DEPRECIATION>                               (322,485)
<TOTAL-ASSETS>                               2,124,664
<CURRENT-LIABILITIES>                          115,672
<BONDS>                                        400,000
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           696
<OTHER-SE>                                   1,398,374
<TOTAL-LIABILITY-AND-EQUITY>                 2,124,664
<SALES>                                              0
<TOTAL-REVENUES>                               433,267
<CGS>                                                0
<TOTAL-COSTS>                                  187,960<F1>
<OTHER-EXPENSES>                                62,772<F2>
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               3,349
<INCOME-PRETAX>                                187,403
<INCOME-TAX>                                    65,939
<INCOME-CONTINUING>                            121,464
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   121,464
<EPS-PRIMARY>                                     1.70<F3>
<EPS-DILUTED>                                     1.70<F3>
<FN>
<F1>Includes contract drilling expenses only.
<F2>Includes other operating expenses.
<F3>Per share amounts do not reflect the effect of the two-for-one stock split in
the form of a stock dividend to stockholders of record on July 24, 1997. On a
post-split basis, earnings per share - primary and earnings per share - fully
diluted will be restated to $0.85 for the six months ended June 30, 1997.
</FN>