01 May 2010

Extreme Measures Necessary to Shut Down Leaking Well


BP concedes that a relief well will eventually have to be drilled in order to successfully shut down the existing leaking well. The graphic below explains what's happening on the ocean floor, and how the relief well will work. _NOLA

The graphic image makes clear that the blowout preventer at the wellhead failed, and that the drilling riser is leaking from multiple sites.
Blowout preventers (BOPs) are designed to deal with bubbles. Different control valves and rams can close in the well to various degrees (i.e. think of the difference between a sphincter and a guillotine). Why wasn't the BOP engaged at the time of the "kick." Perhaps there wasn't enough time to act. Even then, the big mystery is why the BOP still can't be activated now by the robotic submarines (ROVs) sent to the scene.

Some scenarios. Assume the workers did try to engage the BOP, but it didn't work. Why? One analyst I spoke with suggested that it could be that the kick pushed newly poured cement out of the casing, gumming up the controls. I ran that idea by a subsea engineer who has been responsible for BOPs in deepwater drilling offshore Brazil, and he felt it could be within the realm of possibility.

Another possibility--they tried to engage the BOP's shear ram (which is supposed to slice through the riser and seal off the hole) but there was something too big to shear. That could have been a solid steel joint between two sections of drill pipe. These joints come along about one foot in every 30 feet of pipe, so it would have been very unlucky for such a joint to be sitting right where the shear ram would try to cut--but possible.

Video shot by the robotic submarines (a.k.a. remote operated vehicles or ROVs) seems to indicate that oil is leaking from three spots in a pipe that is laying on the seafloor. The pipe would have to be a portion of the riser, which would have to still be attached to the BOP, but crimped and bent over. An uncuttable piece of joint lodged in the shear ram would perhaps explain why the ROVs haven't been able to subsequently engage the ram. _Forbes
Bad weather has complicated efforts to stop the leak and contain the spill. Estimates of the rate of leakage have ranged from 1,000 barrels per day up to 25,000 barrels per day. At a rate of 25,000 barrels of oil leaking per day, it would take only 10 days to match the oil discharge of the Exxon Valdez. The true amount of leakage will not be determined for some time.

Deep ocean drilling is a very hazardous undertaking. Apparently the Transoceanic blowout occurred at one of the most critical points of securing the wellhead. The entire process will have to be put under the magnifying glass and dispassionately examined.

Nature deals with large natural oil spills every day. Human intervention and mitigation of the oil slick should be able to limit the temporary damage to natural ecosystems.

This episode does bring up an important concern about human limitations. Only certain types of people can work with the unpredictable hazards of deep sea construction and industry. The supply of such persons is not unlimited. Peak manpower is probably the most critical peak we will confront in the struggle to get out of the "between levels" quagmire that humans find themselves in.

Likewise, too many nations have outsourced most of their heavy industrial equipment manufacturing to just a few East Asian countries. In the event of catastrophic failures and destruction of heavy industrial equipment -- such as high voltage transformers, large power turbines, or heavy drilling equipment -- replacements may take a long time to arrive. In other words, by relying too much on outsourcing of manufacturing, some advanced nations may be making their industrial and commercial infrastructure unnecessarily vulnerable to unexpected breakdowns, sabotage, or natural disaster.

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