Soaring oil and gas prices have doubled the fortune of former Exxon geologist; today owns third-largest privately held oil company in America. Founded Hilcorp Energy 1989 with partner Thomas Hook; bought former Goldman Sachs banker out for $500 million 2003. Loaded up on debt to finance expansion. Pumped an estimated 13.1 million barrels of oil and natural gas equivalents from 1,900 wells in 2007. Buys proven oilfields, deploys technology to extract more energy. Acquired 19 fields in Gulf of Mexico from Chevron in August. Gives to Houston Zoo, Contemporary Arts Museum, Houston.