press release

Unocal subsidiary will make offer to purchase all outstanding shares of Northrock Resources Ltd.

El Segundo, Calif., May 19, 2000 - Unocal Corporation (NYSE: UCL) today said that its Unocal Canada Management Limited subsidiary will proceed with the previously announced offer of C$10.10 per share for the approximately 21.9 million shares (52%) of Northrock Resources Ltd. (TSE: NRK) that Unocal does not already own.

Unocal Canada Resources, a partnership held by various Unocal subsidiaries, currently owns 19.8 million shares (48%) of Northrock, which were acquired in transactions in May and December of 1999.

Unocal Canada Management will be making this offer with the consent of, and in full cooperation with, Northrock, pursuant to a support agreement regarding the offer between Unocal Canada Resources and Northrock.

A special committee of independent directors of Northrock, formed to consider the offer, supervised a valuation of Northrock's shares by FirstEnergy Capital Corp., independent financial advisors to the special committee. FirstEnergy has concluded that the Unocal offer is fair from a financial point of view to the Northrock shareholders, other than Unocal. After receiving FirstEnergy's valuation and fairness opinion, the special committee and Northrock's board of directors recommended that Northrock's shareholders should deposit their shares to the offer.

The offer for the remaining shares of Northrock will be subject to certain conditions, including obtaining all required regulatory approvals and that a minimum of 90 percent of the Northrock shares not already owned by Unocal Canada Resources are tendered to the offer.

A take-over bid circular containing the offer will be mailed to Northrock shareholders of record as soon as reasonably possible.

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. In North America, Unocal is one of the largest independent natural gas producers, with current net production of 1 billion cubic feet per day.

Forward looking statements regarding commercial acquisition activities in this news release are based on assumptions concerning market, operational, competitive, regulatory, environmental, and other considerations. Actual results could differ materially as a result the foregoing and other factors as outlined in Unocal's 1999 Form 10-K report filed with the Securities and Exchange Commission.

Updated: May 2000