press release

Unocal reports 159-percent reserve replacement ratio for 1999

El Segundo, Calif., Feb. 7, 2000 -- Unocal Corporation today said it replaced 159 percent of its net worldwide crude oil and natural gas production during 1999 with new proved reserves.

At year-end 1999, Unocal's net worldwide reserves totaled 1.66 billion barrels-of-oil-equivalent (BOE), up 7 percent from 1.55 billion BOE the year before.

During 1999, the company added reserves of 289 million BOE, including 107 million BOE from net purchases and sales and 182 million BOE from all other sources. Net production for the year was 181 million BOE. About two-thirds of Unocal's proved reserves are natural gas. Approximately 72 percent of the reserves are outside the U.S.

Excluding purchases and sales, the company replaced 100 percent of its worldwide production during 1999.

Unocal holds a 47.8-percent interest in Canada-based Northrock Resources Ltd., which is accounted for on a consolidated basis. Excluding the minority share of Northrock, the company's overall estimated reserve replacement ratio was 131 percent.

"Our overall reserve replacement performance is the best for Unocal since 1990," said Roger C. Beach, Unocal chairman and chief executive officer. "We are successfully transitioning to a growth and return-oriented E&P company with a focus on bringing additional production and reserves onto the books."

International operations

Unocal's international operations replaced 242 percent of production in 1999 from all sources. Excluding purchases and sales, the replacement ratio was 129 percent. At year-end, total international reserves were 1.19 billion BOE, up 14 percent from the previous year. This included 95 million BOE due to the acquisition of Northrock.

More than 100 million BOE in new reserves came from Unocal's exploration

program in Thailand and Indonesia. "We added significant new gas reserves in the Gulf of Thailand through the discovery of new fields and infill drilling in existing contract areas," Beach said. "In Indonesia, we booked additional oil and gas reserves both on the shelf and in the deepwater PSC areas."

Spirit Energy 76

Spirit Energy 76, Unocal's Lower 48 exploration and production unit, replaced 65 percent of its production in 1999 with new reserves. In total, Spirit booked more than 34 million BOE from discoveries and extensions, including the new Muni field on Ship Shoal 295 and the long-producing Vermilion 39 field.

Spirit's reserve performance was affected by low exploration capital expenditures in 1999 in response to oil prices. The 1999 reserves also do not include any additions for deepwater Gulf of Mexico discoveries.

Costs

For the year, Unocal's finding, development and acquisition (FD&A) costs for new reserves were $4.90 per BOE. Excluding the minority interest in Northrock, FD&A costs were $5.69 per BOE.

Unocal's worldwide F&D costs, excluding purchases, were $6.95/BOE. Excluding Spirit deepwater, the effective F&D costs are $5.89/BOE.

Resource potential

With the current growth portfolio, Unocal estimates its total oil and gas risked resource base at 7.1 to 9.9 billion BOE, including year-end 1999 proved oil and gas reserves of 1.66 billion BOE. The estimate is up from 6.0 to 8.2 billion BOE last year, which included proved reserves of 1.55 billion BOE. The additional potential comes principally from new prospects in deepwater Brazil and West Africa and in Bangladesh. The unproved resource base includes discovered and potential resources with price and market risk. It also includes targeted opportunities not yet captured by contract, which aggregated approximately 700 million BOE to 1 billion BOE at year-end 1999.

Unocal is a leading global oil and gas exploration and production company with significant pipeline and power plant project developments worldwide. For more information about the company, visit Unocal's web site at www.unocal.com.

Forward-looking statements and estimates regarding reserves, future reserve replacement and resource potential in this news release are based on assumptions concerning operational, market, competitive, regulatory, geological, pricing, environmental, cost, and other considerations. Actual results could differ materially as a result of factors discussed in Unocal Corporation's 1998 Form 10-K report filed with the U.S. Securities and Exchange Commission.

The following tables provide details on the company's reserves and FD&A costs.

    UNOCAL CORPORATION
    Crude Oil and Natural Gas Reserve Data

    Estimated proved reserves of crude oil, condensate and natural 
    gas (Revised 3/14/00)

                                     Crude Oil   Natural Gas   Oil Equivalent
                                     (MMbbls)       (bcf)         (MMBOE)

    1999 beginning reserves             532           6,122         1,552
     Discoveries and extensions          31             705           148
     Improved recovery                    2              50            11
     Revisions                           26             (20)           23
     Purchases                           38             582           135
     Sales                              (15)           (115)          (35)
    Production                          (64)           (706)         (181)
    2000 beginning Reserves*            550           6,618         1,653

    * Includes host country shares
       for Indonesia and Democratic
       Republic of Congo of:             46             441           120

    Estimated proved reserves by geographic area (millions of BOE)

                             Consolidated Subsidiaries
                      Spirit    Other   Far    Other
                      Energy     U.S.  East    Inter   Total  Affil  World
                        76                   -national        -iates -wide

    1999 beginning
     reserves            376     125     849     196   1,546     6   1,552
      Discoveries
       and extensions     34       3     100      11     148    --     148
      Improved recovery    4      --       7      --      11    --      11
      Revisions            6       5      12      (1)     22     1      23
      Purchases            4      --      --     116     120    15     135
      Sales              (24)     (1)     --     (10)    (35)   --     (35)
    Production           (59)    (20)    (80)    (20)   (179)   (2)   (181)
    2000 beginning
     reserves*           341     112     888     292   1,633    20   1,653

    * Includes host
      country shares
      for Indonesia and
      Democratic Republic
      of Congo of:                       118       2     120           120

Notes: Other U.S. is principally Alaska. Far East includes Thailand, Indonesia and Myanmar. Other International includes Azerbaijan, Bangladesh, Canada, Democratic Republic of Congo, Yemen and Netherlands. Included in Spirit Energy's year-end 1999 reserves are 55 mmboe attributable to Spirit Energy 76 Development, L.P., a consolidated subsidiary, in which there is a minority interest share representing approximately 24 mmboe. Other International's year-end 1999 reserves include 92 mmboe attributable to Northrock Resources Ltd, a consolidated subsidiary, in which there is a minority interest share representing approximately 48 mmboe.

Purchases and Sales include reserves acquired and relinquished through property exchanges of 14 mmboe for Spirit Energy and 10 mmboe for Other International for which there were no costs incurred.

For the above, natural gas is converted at a ratio of 6 mcf to one barrel of oil.

    Preliminary 1999 finding, development & acquisition costs per BOE

                                               Spirit Energy           Other
                                      Deepwater     Mature    Total     U.S.

    Costs incurred (millions
     of dollars)
      Exploration                         180        169       349        5
      Development                          13        227       240       25
      Proved property acquisitions        ---         18        18      ---
      Northrock acquisition               ---        ---       ---      ---
    Total consolidated costs
     incurred                             193        414       607       30
      Share of equity affiliates          ---         11        11      ---
    Worldwide Costs Incurred (a)          193        425       618       30

    Reserve data (millions of BOE) (b)
      Discoveries/extensions              ---         34        34        3
      Improved recovery                   ---          4         4      ---
      Revisions                           ---          7         7        5
      Purchases                           ---         19        19      ---
    Total changes                         ---         64        64        8

    Finding & development
    Costs per BOE (c)                     ---      $9.17    $13.50    $3.77

    Finding, development & acquisition
    Costs per BOE (d)                     ---      $6.70     $9.74    $3.77

    FD&A costs per BOE excluding
    Northrock Resources Ltd. minority
     interest share (d, e)                ---      $6.70     $9.74    $3.77


                                         Far       Other    Total     Total
                                        East       Int'l    Int'l   Worldwide

    Costs incurred (millions
     of dollars)
      Exploration                         161        141       302      656
      Development                         204        122       326      591
      Proved property acquisitions        ---         31        31       49
      Northrock acquisition               ---        274       274      274
    Total consolidated costs incurred     365        568       933    1,570
      Share of equity affiliates            4        ---         4       15
    Worldwide Costs Incurred (a)          369        568       937    1,585

    Reserve data (millions of BOE) (b)
      Discoveries/extensions              100         11       111      148
      Improved recovery                     7        ---         7       11
      Revisions                            12        (1)        11       23
      Purchases                           ---        123       123      142
    Total changes                         119        133       252      324

    Finding & development
    Costs per BOE (c)                   $3.10     $25.14     $4.89    $6.95

    Finding, development & acquisition
    Costs per BOE (d)                   $3.10      $4.48     $3.82    $5.00

    FD&A costs per BOE excluding
    Northrock Resources Ltd. minority
     interest share (d, e)              $3.10      $6.80     $4.54    $5.76

    (a) Excludes properties acquired through property exchanges by definition.
    (b) Includes equity interest in reserves of affiliates and 100% of
        Northrock's reserves.
    (c) Excludes proved property acquisition costs and purchased volumes.
    (d) Includes reserves and equity interests in affiliate reserves acquired
        in property exchanges.
    (e) Excludes minority interest share of costs ($53MM) and minority
        interests share of reserves (51 mmboe)

Updated: February 2000