Thursday, August 5, 2010

BP Oil Leak Update August

A “leak” or “spill” does not covey the damage and impact of the 4.9 million barrels (205,800,000 gallons) of oil that the government and BP currently estimate were released from the BP-Horizon Macondo well into the waters of Gulf of Mexico beginning on the night of April 20th with the explosion of the Deepwater Horizon oil rig and ending on July 15th when the current 75-ton cap was placed on the well. The cap referred to as Top Hat Number 10 has been keeping the oil bottled up inside over the past three weeks. So the flow stopped and allowed the scientists to make more accurate estimates of the size of the entire spill.

Stopping the flow using the cap was only a temporary measure. BP and the Coast Guard are executing a three step plan to permanently stop the flow of the Macondo well. First the current larger cap was put in place and has held for almost three weeks. Now, after repairing seals, and carefully testing, they slowly pumped the mud from a ship down lines to the top of the ruptured well a mile below. Though BP has said that may be enough by itself to seal the well, the Coast Guard Admiral Allen is requiring the completion of the three step procedure to seal the leak. After about eight hours of pumping drilling mud for the “static kill" procedure they stopped and were monitoring the well to ensure it remained stable. This appeared to be the completion of the second step in permanently sealing the leak.

It was unclear how much drilling mud would be needed to seal the well because the condition of the well itself was unknown. There are three different of areas of the well that might ultimately need to be filled with mud. The drill pipe, the casing, and the area between the casing and the drill pipe, the annulus, to fully seal the well and leave no routes for gas or oil to bypass the drilling mud. The current monitoring is to determine if all areas have been sealed and are stable. The drilling mud itself is not entirely impervious to gas or oil working its way up so the final step for permanently sealing the well will be to inject mud and cement into the bedrock from the 18,000-foot relief well BP has been drilling for the past three months. This is the "bottom kill," that will finish the job, according to Coast Guard Admiral Thad Allen.

With the final and permanent sealing of the leak within grasp it is time to tally up the damage from the 205,800,000 gallons of oil estimated to have been released in the spill. According to the official government web site which is unlikely to overlook taking credit for any of the oil recovered, only a fraction of the oil has been accounted for. The government gives a total of 45,840,000 gallons of oil have been recovered or burned. A total of more than 11,140,000 gallons of oil from the open water have been removed by controlled burns. The government lists 34,700,000 gallons of an oil-water mix have been recovered. I assume this number includes the 33,600,000 gallons of oil that BP captured from the previous caps and that appeared to be supported by the data published yesterday on the NOAA web site. That would mean that the other methods of recovery, including skimming had captured only 1,100,000 gallons. NOAA reports that A third (33 percent) of the total amount of oil released in the Deepwater Horizon/BP oil spill was captured or mitigated by the Unified Command recovery operations, including burning, skimming, chemical dispersion and direct recovery from the wellhead, so that would imply that 22,100,000 gallons of oil was mitigated by chemical dispersion. In an effort to accelerate the breakdown of the oil approximately 1.84 million gallons of dispersants have been released into the waters of the Gulf of Mexico, 1.07 million gallons on the surface and 771,000 gallons sub-sea. The long term impacts of this release especially the deep water release of dispersants is unknown. The government also estimates that 25 percent of the total oil naturally evaporated or dissolved, and 16 percent was dispersed naturally into microscopic droplets. The residual 26 percent or 53,500,000 gallons of oil, is either on or just below the surface as residue and weathered tarballs, has washed ashore or been collected from the shore, or is buried in sand and sediments.

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