Ixtoc I Blows Out: Gulf's Worst Spill Begins

Drilling mud stopped circulating at 3:00 AM, and the crew of the Sedco 135F knew they were in trouble. The exploratory well Ixtoc I, operated by Mexico’s state oil company Pemex in the Bay of Campeche 600 miles south of Texas, blew out on June 3, 1979, when pressurized oil and gas roared up the wellbore and ignited. The drilling rig collapsed into the sea. The well would not be capped for nine months. Ixtoc I released an estimated 3.3 million barrels of crude oil into the Gulf of Mexico, making it the second-largest accidental oil spill in history at the time. Oil slicks spread across 1,100 square miles. Prevailing currents carried crude northward to the Texas coastline, where tar balls fouled 162 miles of beaches from the Rio Grande to Corpus Christi. Mexican shrimpers and fishermen lost an entire season’s income. Sea turtles, dolphins, and seabird populations suffered losses that scientists struggled to quantify because baseline population data barely existed. Pemex attempted every available technique to stop the flow. Workers dropped steel balls and debris into the wellbore, injected chemical gelling agents, and used relief wells to intersect the blown-out shaft. Two relief wells were drilled simultaneously starting in June, but the geology of the seafloor complicated the drilling. Oil continued to pour out at a rate of 10,000 to 30,000 barrels per day throughout the summer and fall. The well was finally capped on March 23, 1980, 295 days after the blowout. The disaster produced recommendations for blowout prevention that went largely unimplemented. Thirty-one years later, the Deepwater Horizon spill in the same Gulf of Mexico repeated many of the same failures at far greater depth, suggesting that the lessons of Ixtoc I were studied but never absorbed by the industry.