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Deepwater Horizon oil spill

 

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Deepwater horizon oil spill, also know as gulf of mexico oil spill, is considered the largest accidental oil spill in the history of petroleum industry. It is 8% to 31% larger than the previous largest oil spill, the Ixtoc I oil spill, causing 11 deaths, 17 injuries, and 4.9 million barrels (780,000 cubed meters) of oil spilled into the gulf.  It began on April 20th, 2010 in the Deepwater horizon oil rig that was located in the Gulf of mexico and lasted for 87 days until July 15th, 2010 despite  numerous efforts of stopping the spill.

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The causes of the catastrophe can be brought down to a lack of suitable approach for managing the inherent risk, uncertainties, failure to learn from ” near misses,” asserted the  interim report of preliminary findings from a committee of the National Academy of Engineering and National Research Council. Donald Winter, former secretary of the Navy, professor of engineering practice at the University of Michigan, and chair of the study committee says:”Important decisions made to proceed toward well abandonment despite several indications of potential hazard suggest an insufficient consideration of risks.”

From an engineering point of view one could describe what happened as follows: Six-Steps-Oil-Spill-Animation

1-   Fewer barriers to gas flow at the bottom of the well:

There was only one long string of casing in the middle of the drill hole.

2- Insufficient centralizers to keep cement even:

The rig was built with only six devices for keeping tubes centered, ignoring models that have the casing centered in the well hole for cement to set evenly.

3- Bond log test was ignored:

bond log tests are used to measure cement integrity. However in the process of designing the Deepwater Horizon this test was ignored.

4- Misinterpretation of pressure test:

This test measures well stability and in the process workers reported confusion over the negative test that measured upward pressure from the shut-in well.

5- Mud barrier removed early:

The removal of heavy mud while drilling 3000 ft below the normal point caused gas to move freely without any barriers.

6- Failure of the Blowout Preventer:

The combination of increased pressure and a stuck drilling pipe caused a section of the pipe to bend and jam the blowout preventor.

Disaster in The Gulf

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