press release

Unocal replaces 222 percent of 2001 crude oil, natgas production

El Segundo, Calif., Jan. 28, 2002 -- Unocal Corporation (NYSE: UCL) today said it replaced 222 percent of its worldwide crude oil and natural gas production during 2001 with new proved reserves.

At year-end 2001, Unocal's preliminary estimate of worldwide reserves totaled 1.81 billion barrels-of-oil-equivalent (BOE), up 15 percent from 1.58 billion BOE the year before.

"Every one of our major production areas contributed to the reserve replacement in 2001, which was among the highest in the company's history," said Charles R. Williamson, Unocal chairman and chief executive officer. "We booked our first reserves from the Mad Dog field, a new deepwater development in the Gulf of Mexico, and added to our reserves in Azerbaijan, Thailand, Indonesia, the GOM region, onshore Texas and Alaska through the drillbit."

During 2001, the company added reserves of 241 million BOE from discoveries and extensions and improved recovery. Reserve acquisitions onshore Texas, in the GOM shelf, Brazil and Canada totaled 113 million BOE. Unocal also made net upward revisions of 80 million BOE because of price effects and reservoir performance. Because of cost recovery provisions in certain production-sharing contracts, reserves increase when prices decline.

Production of 193 million BOE and the sale of 5 million BOE in reserves partially offset the increases.

For the year, preliminary worldwide finding and development (F&D) costs were $5.39 per BOE. Unocal's preliminary estimated worldwide finding, development and acquisition (FD&A) costs for new reserves were $6.18 per BOE.

Reserve details

Details of Unocal's estimated proved reserves and finding, development and acquisition costs will be published in the company's 2001 Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission in March 2002.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company's principal oil and gas operations are located in North America (Gulf of Mexico region, Permian Basin, Alaska and Canada) and in Asia (Thailand, Myanmar, Indonesia, Bangladesh and Azerbaijan). The company is also pursuing exploration programs in Brazil and West Africa. Unocal is one of the world's largest producers of geothermal energy with operations in the Philippines and Indonesia.

Unocal preliminary estimated proved reserves of crude oil and natural gas (MMBOE)
As of December 31, 2000 1,578
Discoveries and extensions 228
Improved recovery 13
Revisions 80
Purchases 113
Sales (5)
Production (193)
As of December 31, 2001 1,814

Unocal's reserves reflect a change in the reporting method for reserves and production in Indonesia and the Democratic Republic of Congo that was initiated in 2001. All production-sharing contracts are now reported on the economic interest method, which excludes host-country shares. The year-end 2000 numbers have been restated to reflect the change in reporting methods. The year-end 2000 and 2001 reserves include minority interests in consolidated subsidiaries of 69 MMBOE and 97 MMBOE, respectively.

This news release contains certain forward-looking statements about proved reserves, production and costs. These statements are not guarantees of future performance. Proved reserves, as defined by the U.S. Securities and Exchange Commission (SEC), are the estimated quantities of crude oil, natural gas and natural gas liquids that geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and operating conditions. Proved reserve quantities exclude royalty and other interests owned by others. The statements are based upon Unocal's current expectations and beliefs and are subject to a number of known and unknown risks and uncertainties that could cause actual results to differ materially from those described in the forward looking statements. Actual results could differ materially as a result of factors discussed in Unocal's 2000 Annual Report on Form 10-K and subsequent reports filed with the U.S. Securities and Exchange Commission. Unocal undertakes no obligation to update the information in this news release.

Investors are urged to consider closely the disclosure in Unocal's 2000 Annual Report Form 10-K and other reports (SEC File No. 1-8483). Copies of the company's SEC filings are available from the company by calling 800-252-2233 or from the SEC by calling 800-SEC-0330. The reports are also available on the Unocal web site.

Updated: January 2002