By CATHY BUSSEWITZ NEW YORK (AP) — ConocoPhillips is buying shale producer Concho Resources in an all-stock deal valued at $9.7 billion making it a major presence in the Permian Basin, the top-producing oil field in the U.S. The combined company, if approved, would be among the largest independent U.S. oil producers, with production of more than 1.5 million barrels of oil equivalent per day, a resource