In 1953, the Birmingham, Alabama-based Southern Natural Gas Company created The Offshore Company after acquiring the joint drilling operation DeLong-McDermott from DeLong Engineering and J. Ray McDermott. In 1954, the company launched Rig 51, the first mobile jackup rig, in the Gulf of Mexico. In 1967, the Offshore Company went public. In 1978, SNG turned it into a wholly owned subsidiary. In 1982, it was changed to Sonat Offshore Drilling Inc., reflecting a change in its parent's name. William C. O'Malley, an executive at Sonat's headquarters in Birmingham, was named the company's first Chief Executive Officer in 1992. In 1993, Sonat spun off the majority of its ownership in the company. Sonat sold its remaining 40% stake in the company during a secondary public offering in late 1995.