press release

Unocal completes successful appraisal well at Harvest deep shelf discovery

Sugar Land, Texas, Oct. 28, 2003 - Unocal Corporation (NYSE: UCL) today said it has drilled a successful appraisal well on its Harvest deep shelf field on West Cameron block 44 in the Gulf of Mexico.

The Harvest-2 well was drilled to a total depth of 14,322 feet and encountered more than 140 feet of net natural gas pay, including 110 continuous feet of pay in one high-quality interval.

Harvest-2 was drilled more than one-half mile from the Harvest-1 discovery well. Harvest-1 had encountered 70 feet of net gas pay and is currently producing 35 to 40 million cubic feet (mmcf) of gas per day. Unocal said it expects the Harvest-2 well to begin production in mid-December at a rate that is likely to be higher than the Harvest-1 well.

Unocal is also formulating plans for a second appraisal well on West Cameron block 44 in 2004 and evaluating follow-up drilling opportunities on nearby West Cameron blocks 22 and 57.

Unocal is operator of West Cameron block 44 and holds a 41-percent working interest. Co-venturers are Marlin Energy Offshore, LLC, which has a 37-percent working interest; The William G. Helis Company, LLC, with a 20-percent interest; and Houston Energy, LP, which holds the remaining 2 percent.

The company said that it also made a discovery at its deep shelf exploration well on the Red Pepper prospect (High Island block 37). The well found 55 feet of net natural gas pay and began producing 40 days after the rig moved off location. Red Pepper is now flowing at a rate of 25 mmcfd. Unocal has a 36-percent working interest; its co-venturers are Seneca Resources Corporation 25-percent, Fidelity Exploration & Production Company 25-percent, and The William G. Helis Company, L.L.C. 14-percent.

The company's exploratory well on the Comanchero prospect on Eugene Island 37 is a dry hole. Unocal will take a pre-tax $2.4 million charge to third quarter earnings for the well.

Unocal currently has four more deep shelf exploration wells drilling - La Grange (West Cameron 41), House Payment (Eugene Island 40), Acadiana (onshore Louisiana), and Thin Red Line (South Timbalier block 214). Results of these wells should be available by year-end.

This news release contains certain forward-looking statements about expected about future drilling plans and production. These statements are not guarantees of future performance. 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 changes in commodity prices; the levels of the company's oil and gas production; the extent of the company's operating cash flow and other capital resources available to fund its capital expenditures; regulatory, geological, operating and economic considerations; and other factors discussed in Unocal's 2002 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 2002 Annual Report on Form 10-K and other reports filed with the SEC (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: October 2003