Occidental Petroleum Corporation, through its subsidiaries, primarily engages in the exploration, development, production, and marketing of crude oil and natural gas in the United States and internationally. It holds interests in the Permian basin located in west Texas and New Mexico; Elk Hills oil and gas field in California; Hugoton field located in Kansas and Oklahoma; Horn Mountain oil field in the Gulf of Mexico; and the Piceance basin located in western Colorado. The company also has inter ...