GlobalSantaFe Corp., Houston, (NYSE: GSF) and Transocean Inc., Houston, (NYSE: RIG) plan to combine in a merger of equals with an estimated enterprise value of approximately $53 billion. GlobalSantaFe provides offshore oil and gas contract drilling services primarily in the U.S. Gulf of Mexico, the North Sea, West Africa, the Mediterranean Sea, Southeast Asia, South America, the Middle East and eastern Canada. As of year-end 2006, the company owned and operated a fleet of 59 marine drilling rigs, including 43 cantilevered jackup rigs, 11 semisubmersible rigs, three drillships, and two additional semisubmersible rigs. Transocean provides offshore contract drilling services primarily in the Far East, India, U.S. Gulf of Mexico, U.K. Nigeria, the Mediterranean and Middle East, Brazil, Norway, other West African countries, Australia, Canada, the Caspian Sea, and Venezuela. As of Feb. 2, the company owned and operated 82 mobile offshore and barge drilling units, including 33 high-specification semisubmersibles and drillships, 20 floaters, 25 jackup rigs, and four other rigs.