division by acquiring Zilkha Energy for $1.3 billion. Merger with El Paso In March 1999, Sonat announced it was merging with El Paso Corporation in a $6 billion deal in an effort for El Paso to maintain competition in the natural gas markets. At the time of the merger, Sonat was a Fortune 500 company. The E&P unit, Sonat Exploration Company, was blended into El Paso's organization, and the gas transmission unit, Southern Natural Gas Company, is still headquartered in the Birmingham area. Sonat divisions Sonat Inc.'s corporate headquarters and several of its divisions were located in Birmingham, Alabama, in the AmSouth-Sonat Tower. Sonat also had offices in Houston, Oklahoma City, Washington D.C., New York City, and London. By 1999, the company's divisions consisted of natural gas distribution, natural gas marketing, and exploration and production. Southern Natural Gas Company Southern Natural Gas Company, headquartered in Birmingham, Alabama, was Sonat's natural gas transmission division. The division owned the Sea Robin Pipeline and 50% of Florida Gas Transmission. Sonat sold the Sea Robin Pipeline in 1999 as a requirement to complete its merger with El Paso. After being acquired by El Paso in 1999, Southern Natural continued to operate as a separate division and kept its corporate headquarters in the AmSouth-Sonat Tower until 2007, when it relocated to the Colonial Brookwood Center located in a suburb of Birmingham. Publicly owned El Paso Pipeline Partners, which is majority owned by El Paso Corp., owns 60% of the company, with El Paso Corp. owning the remaining 40%. Sonat Marketing Sonat Marketing was headquartered in Birmingham, Alabama, and was primarily engaged in the marketing of natural gas. The company also operated Sonat Power Marketing which marketed and sold electrical power. Sonat Exploration Sonat Exploration Company, headquartered in Houston, Texas, was the exploration and production division of Sonat. The company had regional offices in Fort Smith, Arkansas, Shreveport, Louisiana, Oklahoma City, Oklahoma, and Houston and Tyler, Texas. As a result of the merger with El Paso, the regional offices were closed and the holdings were blended into El Paso's Exploration and Production division. Former divisions Sonat Offshore/Transocean Sonat Offshore was formed in 1953 by Southern Natural Gas when it established The Offshore Company to own mobile jackup rigs in the Gulf of Mexico. The company's name was changed to Sonat Offshore Drilling in 1982. In 1993, Sonat took Sonat Offshore public. Sonat fully divested itself of