Chevron Corp. has announced its intention to buy the second largest oil exporter in Argentina to boost its exploration and production overseas. The companies did not disclose financial details of the deal, but industry sources had valued the privately-held Petrolera Argentina San Jorge at some $1 billion. "This transaction will have an immediate positive impact on earnings and cash flow," Dick Matzke, president of Chevron Overseas Petroleum Inc., said. The venture is Chevron's first exploration and production deal in Argentina. Privately held San Jorge produces about 78,000 bpd of oil and 40 million cubic feet of natural gas, Chevron officials said.