press release

Unocal reaches equity agreement on deepwater Mad Dog field

Sugar Land, Texas, July 11, 2000 -- Unocal Corporation's Spirit Energy 76 unit today said that an agreement has been reached with the Mad Dog field owners that creates in Unocal a 15.6-percent working interest in an expanded area covering the entire Mad Dog field in the deepwater Gulf of Mexico.

Prior to the revised equity distribution, Unocal held a 25-percent working interest in the original 2-1/2-block unit, which covered Green Canyon blocks 825, 826 and the southern half of block 782.

The co-venturers agreed, based on the results of appraisal drilling, that the Mad Dog field likely extends beyond the original drilling unit into surrounding blocks. The agreement expands the Mad Dog field to include Green Canyon blocks 738, 739, 781, 783, 827 and the northern half of block 782.

Additional appraisal drilling is planned. BP Amoco is operator for the Mad Dog field.

When Unocal announced the initial oil discovery on April 12, 1999, it said Mad Dog was a very significant discovery that could represent a "trend opening" discovery for the deepwater fold belt subsalt play where the company has significant interests.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company also focuses on pipeline and power plant projects in Asia and the Americas.

At year-end 1999, the company had worldwide natural gas reserves of 6.6 trillion cubic feet, representing two-thirds of the company's overall hydrocarbon reserves. Unocal's net worldwide natural gas production averaged more than 1.8 billion cubic feet per day. This includes 1 billion cubic feet per day in North America, where Unocal is one of the largest independent natural gas producers.

Forward-looking statements regarding future exploration activities and reserves are based on assumptions concerning operational, market, competitive, regulatory, environmental and other considerations. Actual results could differ materially as a result of the foregoing and other factors discussed in Unocal's 1999 Form 10-K report filed with the U.S. Securities and Exchange Commission.

Updated: July 2000