The worst blowout on record took about nine months to cap using two relief wells, the same technique BP Plc has said it will deploy to stem gushing crude from the Macondo well in the Gulf of Mexico.
In 1979, Ixtoc-1, an exploratory well owned by Petroleos Mexicanos in 150 feet of water, blew out 600 miles (966 kilometers) south of Texas in Mexico’s Bay of Campeche and spilled an estimated 3.3 million barrels into the Gulf, according to the Royal Swedish Academy of Sciences and the American Petroleum Institute.
Oil from the BP well, which blew out April 20, is escaping at a rate of about 5,000 barrels a day, five times faster than previously estimated, according to the U.S. Coast Guard. The Deepwater Horizon rig exploded and sank last week, killing 11 crew members, while drilling in 5,000 feet of water.
“There is likely going to be more oil coming ashore than Ixtoc,” Paul Boehm, who was an oceanography contractor with the National Oceanic and Atmospheric Administration at the time of the 1979 spill, said today in a phone interview. “This spill has challenges that nobody has faced before.”
The oil and natural gas blowing out of Ixtoc-1 ignited, causing the platform to catch fire, according to NOAA. The platform collapsed into the wellhead area, hindering immediate attempts to control the blowout, which spilled 10,000 to 30,000 barrels of oil a day.
Two wells were drilled to relieve pressure from Ixtoc-1 so that it could be capped, according to NOAA. BP, based in London, said today that its relief-well operation should begin tomorrow.
The differences between the two spills are more worrisome than the similarities, said Boehm, who is now principal scientist at Exponent Inc., a scientific and engineering company in Boston.
The oil from Ixtoc-1 took two months to be transported, which changed the composition of the crude and made it less toxic, Boehm said. The length of time allowed U.S. responders to prepare for the spill. The composition of the oil from the BP well will be different, Boehm said.
“The oil has been out there eight days now,” he said. “The more it weathers, the less toxic it is.”
About 71,500 barrels of oil from Ixtoc-1 affected 162 miles of U.S. beaches and more than 10,000 cubic yards of oiled material were removed, according to the Industry Technical Advisory Committee, a U.K.-based oil-spill organization of technical experts. The U.S. Fish and Wildlife Service used volunteers for handling oiled birds and beach patrols on South Padre Island.
“This will be a lot worse,” said Miles Hays, a coastal geologist with Research Planning Inc. in Columbia, South Carolina, who studied the Ixtoc-1 spill.
The oil from the Ixtoc-1 spill hit the 90-miles of Texas barrier islands, protecting the environmentally fragile marsh lands from the spill, Hayes said in a phone interview.
“You want to keep the oil from getting past the barrier islands,” Hayes said. “After Ixtoc, in Texas it wasn’t too tough because we had only three inlets. Louisiana is a different scenario.”