It may not be as well known as Chevron (CVX) or Exxon Mobil (XOM), but EOG Resources has grown into a pretty big oil and gas firm. EOG Resources (EOG), with market capitalization of over $63 billion, has been growing fast as an exploration and production firm that specializes in horizontal drilling. Although it has operations in a few other countries, most of its work is in the U.S. and Canada.