(This was written yesterday, but still a valuable post)
While horrified by the Deepwater Horizon explosion and BP conduct, we might also recall that today is the anniversary of another horrendous oil spill in the Gulf of Mexico. The parallels between the Ixtoc spill and the current Deepwater Horizon disaster, including failure of the blowout preventer, are striking.
Ixtoc I was an exploratory oil well being drilled in about 160 feet of water in the , in the Gulf of Mexico. On June 3, 1979, the well suffered a blowout resulting in one of the largest environmental disasters ever — still counted as the second largest accidental oil spill in history.
The drilling was by Pemex (Petróleos Mexicanos), Mexico’s government-owned oil company. At the time of the accident, the drilling rig Sedco was operating at a depth of more than two miles (nearly 12,000 feet) below the sea floor, twice as deep as the Deepwater Horizon.
The details are complicated. One gathers, however, that the drill bit hit some kind of soft strata, which caused a loss of drilling mud, which in turn resulted in reduced hydrostatic pressure. When Pemex officials decided to remove the bit, mud began rising toward the surface. The blowout preventer malfunctioned, and oil and gas started escaping. The oil and gas fumes ignited on contact with operating pump motors, starting a fire that led to the collapse of the drilling tower, causing damage to underlying well structures and leading to release of huge quantities of oil.
Initial estimates put the flow from the damaged well at 30,000 barrels of oil per day. From the outset, Pemex officials minimized the extent of the damage, claiming that half of the oil burned on the surface, another third evaporated and the rest was contained or dispersed.
Meanwhile, like BP in the current crisis, Pemex tried a host of disparate measures. An initial effort to put a cap or funnel above the well (like the BP “Top Hat” containment attempt and actually called “Operation Sombrero”) failed. In July 1979, pumping drilling mud into the well (harbinger of BP’s “Top Kill”) reduced the flow from 30,000 to an estimated 20,000 barrels per day. In August, pumping nearly 100,00 metal balls (reminiscent of “Junk Shoot”) lowered it further to 10,000 or so barrels per day. Pemex also sprayed the chemical dispersant Corexit 9527 (used by BP today) on the area affected by the spill. Meanwhile, two relief wells were drilled, but oil continued to escape for three months following completion of the first one.
The bottom line was that, even according to Pemex’s own estimates, around 3.5 million barrels poured into the Gulf before the leak was finally plugged nearly ten months later, on March 23, 1980. The Ixtoc spill caused considerable injury in the United States as well as Mexico. Even thought he U.S. government had two months lead-time to prepare, more than 160 miles of U.S. beaches and countless other Gulf shore interests suffered serious damage.
On a local note, recalling Ixtoc, we in Florida might also question why the offshore drilling studies commissioned by our state Senate and House go back only 20 years for their risk assessment data. Could it be to avoid consideration of this important input some 30 earlier?
Jan Schneider
