<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>
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-END>                               JUN-30-1998
<CASH>                                          57,481
<SECURITIES>                                   326,789
<RECEIVABLES>                                  272,787
<ALLOWANCES>                                         0
<INVENTORY>                                     34,997
<CURRENT-ASSETS>                               720,965
<PP&E>                                       1,894,738
<DEPRECIATION>                                 431,675
<TOTAL-ASSETS>                               2,513,041
<CURRENT-LIABILITIES>                          143,982
<BONDS>                                        400,000
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,393
<OTHER-SE>                                   1,690,659
<TOTAL-LIABILITY-AND-EQUITY>                 2,513,041
<SALES>                                              0
<TOTAL-REVENUES>                               609,586
<CGS>                                                0
<TOTAL-COSTS>                                  241,436<F1>
<OTHER-EXPENSES>                                77,655<F2>
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               7,624
<INCOME-PRETAX>                                297,078
<INCOME-TAX>                                   104,691
<INCOME-CONTINUING>                            192,387
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   192,387
<EPS-PRIMARY>                                     1.38
<EPS-DILUTED>                                     1.32
<FN>
<F1>Includes contract drilling expenses only.
<F2>Includes other operating expenses.
</FN>