press release

Unocal affiliate sells interest in Brazilian production venture

El Segundo, Calif., July 29, 2004 - Unocal Corporation (NYSE: UCL) today said its Unocal Global Ventures II, Ltd., affiliate sold its 50-percent equity interest in a jointly held project company that owns UnoPaso Explorao e Produo de Petrleo e Gs Ltda., a Brazilian exploration and production venture, for $61 million plus approximately $7 million in working capital.

The purchaser is EL Paso Production International Cayman Company, a subsidiary of El Paso Corporation (NYSE: EP), which now owns 100 percent of UnoPaso.

Unocal may also receive up to $19 million in potential additional payments that are contingent on attainment of certain natural gas prices and/or volume thresholds.

The underlying assets sold represent net production of approximately 4,500 barrels-of-oil-equivalent per day to Unocal.

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 activities are in North America and Asia.

This news release contains forward-looking statements about possible contingent payments, and net production impact. Although these statements are based upon Unocal's current expectations and beliefs, they are subject to both known and unknown risks and uncertainties that could cause actual results and outcomes to differ materially from those described in, or implied by, the forward-looking statements, including future natural gas prices, future production volumes from the underlying assets sold in this transaction, and other risks and uncertainties discussed in Unocal's 2003 Annual Report on Form 10-K, as amended, (SEC File No. 1-8483) and other subsequent reports filed by Unocal with the U.S. Securities and Exchange Commission. Unocal undertakes no obligation to update the forward-looking statements in this news release to reflect future events or circumstances.

Updated: July 2004