<PAGE>
                                                                      EXHIBIT 12
 
                              ORYX ENERGY COMPANY
                COMPUTATIONS OF CONSOLIDATED RATIOS OF EARNINGS
               TO FIXED CHARGES AND EARNINGS TO FIXED CHARGES AND
             PREFERRED STOCK DIVIDEND REQUIREMENTS -- UNAUDITED (A)
                             (MILLIONS OF DOLLARS)
 
<TABLE>
<CAPTION>
                                                                                       YEAR ENDED DECEMBER 31
                                                                        -----------------------------------------------------
                                                                          1995       1994       1993       1992       1991
                                                                        ---------  ---------  ---------  ---------  ---------
<S>                                                                     <C>        <C>        <C>        <C>        <C>
RATIO OF EARNINGS TO FIXED CHARGES:
Fixed Charges:
  Consolidated interest cost and debt expense.........................  $     144  $     162  $     163  $     187  $     217
  Interest allocable to rental expense (b)............................         14         13         11         11         13
                                                                        ---------  ---------  ---------  ---------  ---------
    Total.............................................................  $     158  $     175  $     174  $     198  $     230
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
Earnings:
  Consolidated income (loss) before provision (credit) for income
   taxes..............................................................  $     136  $    (100) $    (108) $      (4) $     (52)
  Fixed charges.......................................................        158        175        174        198        230
  Interest capitalized................................................        (10)       (11)       (46)       (43)       (26)
  Amortization of previously capitalized interest.....................          5         14          7          3          3
                                                                        ---------  ---------  ---------  ---------  ---------
    Total.............................................................  $     289  $      78  $      27  $     154  $     155
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
  Ratio of Earnings to Fixed Charges (c)..............................       1.83        .45        .16        .78        .67
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
RATIO OF EARNINGS TO FIXED CHARGES AND
 PREFERRED STOCK DIVIDEND REQUIREMENTS:
Fixed Charges:
  Consolidated interest cost and debt expense.........................  $     144  $     162  $     163  $     187  $     217
  Preferred stock dividend requirements...............................         --          2          8         14         20
  Interest allocable to rental expense (b)............................         14         13         11         11         13
                                                                        ---------  ---------  ---------  ---------  ---------
    Total.............................................................  $     158  $     177  $     182  $     212  $     250
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
Earnings:
  Consolidated income (loss) before provision (credit) for income
   taxes..............................................................  $     136  $    (100) $    (108) $      (4) $     (52)
  Fixed charges.......................................................        158        177        182        212        250
  Interest capitalized................................................        (10)       (11)       (46)       (43)       (26)
  Amortization of previously capitalized interest.....................          5         14          7          3          3
                                                                        ---------  ---------  ---------  ---------  ---------
    Total.............................................................  $     289  $      80  $      35  $     168  $     175
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
Ratio of Earnings to Fixed Charges (c)................................       1.83        .45        .19        .79        .70
                                                                        ---------  ---------  ---------  ---------  ---------
                                                                        ---------  ---------  ---------  ---------  ---------
</TABLE>
 
------------------------
(a) The  consolidated financial  statements of  Oryx Energy  Company include the
    accounts of all subsidiaries (more than 50 percent owned and/or controlled).
(b) Represents one-third of total operating  lease rental expense which is  that
    portion deemed to be interest.
(c) Earnings  for 1994 were inadequate to  cover fixed charges, or fixed charges
    and preferred stock dividend requirements by $97 million. Earnings for  1993
    were inadequate to cover fixed charges, or fixed charges and preferred stock
    dividend  requirements by $147 million. Earnings for 1992 were inadequate to
    cover  fixed  changes,  or  fixed  charges  and  preferred  stock   dividend
    requirements,  by $44  million. Earnings for  1991 were  inadequate to cover
    fixed changes, or fixed charges  and preferred stock dividend  requirements,
    by $75 million.