Earth Protect Blog

The Deepwater Gulf of Mexico oil spill of 2010 is rapidly moving towards the status of the worst accident in U.S. history, and as the disaster moves into its third week a lot of questions are still unanswered, the most obvious being, when is this thing going to stop spewing?

If current estimates for the Deepwater Horizon oil leak are correct, the massive spill could eventually dwarf that of Exxon Valdez spill of 1989 — previously the largest in U.S. history — by as much as three times. At a rate of 5,000 barrels a day, for an estimated 90 days, well over 20 million gallons of crude could be pumped out onto the Louisiana coastline.

This speculation was made last Friday by Foreign Policy Magazine and as the spill gets larger in volume so do the predictions.

So as Republicans speculate on response times and British Petroleum and the Federal Government point fingers the oil continues to spill and questions about safety regulations in regards to offshore drilling begin to arise.  But one has to ask, has this happened in the past?  Of course there are oil spills regularly, this is the third one to happen in 2010, what I’m referring to is an oil spill that relates exclusively to the Deepwater Horizon disaster.  Ohhh but there is…..

Ixtoc I

Ixtoc I was an exploratory oil well in the Gulf of Mexico, about 100 km north west from Ciudad del Carmen in Campeche. On June 3, 1979, the well suffered a blowout and is recognized as the second largest oil spill in history. 

Mexico’s government-owned oil company Pemex (Petróleos Mexicanos) was drilling a 2-mile (3.2 km) deep oil well, when the drilling rig lost drilling mud circulation. In modern rotary drilling, mud is circulated down the drill pipe and back up the casing to the surface. The goal is to equalize the pressure through the shaft and to monitor the returning mud for gas. Without the counter-pressure provided by the circulating mud, the pressure in the formation allowed hydrocarbons to fill the well column, blowing out the well. The hydrocarbons caught fire and the platform collapsed.  At the time of the accident Ixtoc was drilling at a depth of about 11,800 feet (3,600 m) below the seafloor. The day before Ixtoc suffered the blow out and resulting fire that caused her to sink, the drill bit hit a region of soft strata. Subsequently, the circulation of drilling mud was lost. Rather than returning to the surface, the drilling mud was escaping into fractures that had formed in the rock at the bottom of the hole. Pemex officials decided to remove the bit, run the drill pipe back into the hole and pump materials down this open-ended drill pipe in an effort to seal off the fractures that were causing the loss of circulation.  During the removal of the pipe the drilling mud suddenly began to flow up towards the surface. Normally, this flow can be stopped by activating shear rams contained in the Blowout Preventer (BOP). These rams are designed to sever and seal off the the well on the ocean floor, however in this case drill collars had been brought in line with the BOP and the BOP rams were not able to sever the thick steel walls of the drill collars leading to a catastrophic blow out.  The drilling mud was followed by a large quantity of oil and gas at an increasing flow rate. The oil and gas fumes exploded on contact with the operating pump motors, starting a fire which led to the collapse of the drilling tower.

The collapse caused damage to underlying well structures. The damage to the well structures led to the release of significant quantities of oil in to the ocean.  Divers attempted to find a safe approach to the Blowout Preventer (BOP). The approach was complicated by poor visibility and debris on the seafloor including derrick wreckage and 3000 meters of drilling pipe. Divers were eventually able to reach and activate the BOP, but the pressure of the oil and gas caused the valves to begin rupturing. The BOP was reopened to prevent destroying it. Two relief wells were drilled to relieve pressure from the well to allow response personnel to cap it. For 8 months 10,000 to 30,000 barrels of oil gushed into the ocean every day. accumulating in 138 million gallons of oil that seeped into the Gulf of Mexico.