press release

Unocal Midstream & Trade holds first open season at Windy Hill

Sugar Land, Texas, April 27, 2005 - Unocal Midstream & Trade (UMT), a business unit of Unocal Corporation (NYSE: UCL), announced that it is conducting an open season for future natural gas storage capacity at a facility that would be developed on its Windy Hill property in Morgan County, Colorado. If built, this would be the first-ever bedded salt underground natural gas storage facility in Colorado.

Unocal Windy Hill Gas Storage, LLC (Windy Hill) is holding this non-binding open season to secure expressions of interest in firm gas storage services for 6 billion cubic feet (Bcf) of capacity. The open season will begin on April 27 and run through May 18. A 6,500-foot test well was drilled at the facility site last October to assess the thickness, quality, quantity and mechanical properties of the salt. As a result, UMT obtained the technical confirmation needed to move the project forward.

"Given the positive results of the test well and the need for high-deliverability storage services in the Rockies, we are optimistic about taking this project to the next stage," said Joe Blount, president and chief operating officer of UMT. "Through this open season, we'll engage potential customers in the area to see how we can best meet their gas storage needs."

Located near Brush in Northeastern Colorado, Windy Hill's initial 6 Bcf of high-deliverability storage capacity would be developed in two phases with a maximum withdrawal rate of 400 million cubic feet per day (MMcf/d) and an injection rate of 135 MMcf/d. Phase I, expected to be in operation by early 2008, would offer 3 Bcf of working gas capacity.

The proposed design of Windy Hill would ultimately provide up to 9 Bcf of high-deliverability storage capacity to shippers at the Cheyenne and Greensburg Hubs, as well as local Denver markets, via connections with Cheyenne Plains, CIG and Xcel (Public Service Company of Colorado).

Unocal plans to construct Windy Hill as an interstate facility, which will require permits from the Environmental Protection Agency and the Federal Energy Regulatory Commission.

Interested parties wanting to learn more about Windy Hill's open season process or to obtain an information package should contact Steve Hanshaw at 281-287-5804 or or Rex Bigler at 281-287-5513 or

About Unocal Midstream & Trade

Unocal Midstream & Trade, Unocal Corporation's midstream asset management and energy marketing business unit, develops, owns and manages energy infrastructure systems in North America. Specifically, UMT manages storage, pipeline and terminal assets, including interests in 67 Bcf of natural gas storage capacity, 12 million barrels of crude oil and products storage, and more than 8,000 miles of crude oil, natural gas and products pipelines. UMT also markets Unocal's U.S. natural gas and worldwide crude oil and condensate production, as well as some production on behalf of others. Please visit us on the web at

UMT is involved in three working natural gas storage facilities: Keystone Gas Storage in West Texas, which is 100% owned and operated by Unocal, with current working gas capacity of 4 Bcf; Aitken Creek Gas Storage Reservoir, a 48-Bcf facility located in northeastern British Columbia, which UMT operates and owns a 93-percent working interest in through its Unocal Canada Limited subsidiary; and the Alberta Hub, a 37-Bcf gas storage facility near Edson, Alberta, which Unocal owns a 43-percent working interest in, through Unocal Canada Limited.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. With more than 6,000 employees, the company's principal oil and gas activities are in Asia and North America.

This news release contains forward-looking statements about matters such as Windy Hill's open season process, construction and design plans, storage capabilities and pipeline interconnections. 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 fluctuations in demand for natural gas, receipt of required regulatory approvals, operational and economic factors, performance by third party owners and operators of interconnected pipelines and other risks and uncertainties discussed in Unocal's 2004 Annual Report on Form 10-K and other subsequent reports filed by Unocal with the U.S. Securities and Exchange Commission (SEC). Copies of Unocal's SEC filings are available from Unocal by calling 800-252-2233 or from the SEC by calling 800-SEC-0330. The reports are also available on the Unocal web site, Unocal undertakes no obligation to update the forward-looking statements in this news release to reflect future events or circumstances. All such statements are expressly qualified by this cautionary statement, which is provided pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934.

Updated: April 2005