Tri-Valley Proceeds on Drilling Big Oil Creek Prospect.

Business Editors

BAKERSFIELD, Calif.--(BUSINESS WIRE)--July 21, 2003

Tri-Valley Corporation (OTCBB:TRIL) will commence operations to drill its fully funded, major target Oil Creek Prospect near Coalinga, California. The Company believes its data suggests the potential may be the kind of big oil and gas target for which it prefers to explore with six separate prospective zones to be tested.

"In order to add exponential value to our shares and exceptionally reward our investor drilling partners in the event of discovery success, Tri-Valley typically chooses targets of extraordinary size such as this Oil Creek Prospect. A dry hole on a large or small target has the same loss effect, but a discovery on a very large target can bring bonanza returns for all involved. And it helps consumers, too," said F. Lynn Blystone, president and chief executive officer.

The Company assembles data from what it refers to as its data "G" string of sources, including geology, geophysics, geomorphology, geomagnetics, geothermal gradients, geopressure gradients, generation timing, gravity surveys, and a geoproprietary aspect as well as other data.

"If all these compile positive indicators, we add the 10th `G,' `gee whiz,' this ought to be drilled and put together the leases, permits, arrange the deal structure and secure the financing, usually from accredited investors who can stand the risk of total loss. The Oil Creek Prospect has the kind of data strength and size we look for and is located near fields that have already produced nearly two billion barrels of oil and nearly four trillion cubic feet of natural gas," Blystone said.

Sometimes it takes more than one try to attain commercial success as is the case with the Company's Sunrise natural gas play near Delano, California. On its third attempt, with a well drilled horizontally into the tight, but gas-laden McClure Shale formation, Tri-Valley has just hydraulically fractured the formation around the wellbore to more easily liberate the natural gas.

"As the Sunrise well unloads the frac fluid, we are seeing increasing delivery of natural gas and hope to attain commercial flow rates once the well totally cleans up during the coming month," said Joseph R. Kandle, president of Tri-Valley Oil & Gas Co., the operating subsidiary of Tri-Valley Corporation.

If Sunrise is commercially successful, the implications are huge for Tri-Valley as it has mapped a closure on the order of 6,600 acres which could contain more than three trillion cubic feet of gas in place for some degree of recovery to reward Tri-Valley drilling partners and stockholders for taking the risk to assemble and drill the play.

The Company and its subsidiaries are headquartered in Bakersfield, California, a premier oil-producing province of the western hemisphere. Tri-Valley Corporation stock is publicly traded on the over-the-counter bulletin board under the symbol "TRIL.OB" in the United States and in Europe on the Berlin and Frankfurt Stock Exchanges under the symbol "TVC WKN 911919." Our company websites, which include all SEC filings, are www.tri-valleycorp.com and www.tri-valley.de.

This press release contains forward-looking statements that involve risks and uncertainties. Actual results, events and performance could vary materially from those contemplated by these forward-looking statements which include such words and phrases as exploratory, wildcat, prospect, speculates, unproved, prospective, very large, expect, potential, etc. Among the factors that could cause actual results, events and performance to differ materially are risks and uncertainties discussed in the company's quarterly report on Form 10-Q for the quarter ended March 31, 2003, and the annual report on Form 10-K for the year ended December 31, 2002.

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    CONTACT: Tri-Valley Corporation, Bakersfield
             F. Lynn Blystone, 661/864-0500

    KEYWORD: CALIFORNIA
    INDUSTRY KEYWORD: ENERGY OIL/GAS
    SOURCE: Tri-Valley Corporation