Unocal Corporation engages in the exploration, development, and production of natural gas, crude oil, condensate, and natural gas liquids, with principal operations in North America and Asia. It operates in three segments: Exploration and Production, Midstream and Marketing, and Geothermal. Exploration and Production segment engages in the exploration, development, and production of oil and gas. It’s proved oil and gas reserves were 1.754 billion barrels of oil equivalent, as of December 31, 2004. It also operated 10,436 oil and gas producing wells, as of the above date. Midstream and Marketing segment consists of the company's equity interests in petroleum pipeline companies, wholly owned pipelines, and terminals in the United States; the North America gas storage business; and the transporting and selling of hydrocarbon. The Geothermal segment produces geothermal steam for power generation. The company also operates geothermal steam-fired power plants in Indonesia and has equity interests in gas-fired power plants in Thailand. Unocal Corporation was founded in 1890 and is headquartered in El Segundo, California. As of August 10, 2005 Unocal Corp. is a subsidiary of Chevron Corp.