For weeks, the current Deepwater Horizon oil spill has been declared the worst in history and compared in magnitude only to the 1989 Exxon Valdez tanker disaster. Up until a few days ago, however, this claim has been false. On June 3, 1979, the Ixtoc I exploratory oil well suffered a massive blowout while being drilled by the Sedco 135F semi-submersible drilling rig at a depth of 11, 800 ft (3,600 m) below the seafloor in the Gulf of Mexico. The cause of the blowout was due to a loss of drill mud circulation that is necessary to equalize drilling pressure and monitor for the presence of gas. Much like the Deepwater Horizon rig’s fate, oil and gas fumes filled the well shaft and were ignited by pump motors. As a result of the explosion, the Sedco 135F rig burned, collapsed and sank into the Gulf of Mexico.
Unlike the Deepwater Horizon rig, however, the Sedco 135F rig was operating in extremely shallow waters (160 ft) just off the coast of Cuidad del Carmen Mexico. The estimated volume of oil discharge was 3 million barrels spread over 1,100 sq miles of ocean. The Ixtoc I disaster site also featured a continuous gas fire that burned on the surface of the water, making cleanup and relief efforts extremely hazardous. The spill lasted almost 10 months and was finally capped on March 23, 1980. Mexico’s government-owned oil company Pemex (the operator of the rig) paid over $100 million in cleanup costs but avoided most compensation responsibilities by declaring sovereign immunity as a state-run company. Today after 30 years, there is little evidence of this spill in the Gulf waters.