Occidental Petroleum Corp said late Wednesday that it believes it has found the largest oil and gas reserves in the state in 35 years on its Kern County property.

The Los Angeles oil and natural gas producer said it believed 150 million to 250 million gross barrels of oil equivalent had been found at a Central Valley property in which it has an 80 percent interest. About two-thirds of the find is in natural gas.

Occidental, scheduled Thursday to report second-quarter earnings, said it has drilled six wells so far to delineate the discovery.

“It is probable that there are additional reserves outside the defined area,” said Chief Executive Ray Irani in a statement. “We plan to drill wells to exploit these opportunities over the next 5 to 10 years.”

Occidental is California’s largest natural gas producer and the third-largest oil producer, with holdings in the state that include 7,500 active wells in 90 fields. The new find would substantially increased its proved state reserves, which totaled 708 million gross barrels of oil equivalent (BOE) as of the end of 2008. The state reserves account for about a quarter of the company’s global proved reserves.

Before the announcement, Occidental shares closed down 23 cents, or less than 1 percent, to $69.99 on the New York Stock Exchange.