Source:
Business InsiderThe next attempt to shut off the flow from the leaking BP well in the Gulf is still aimed to occur early Wednesday. The attempt will use the “top kill” method to try and kill the well. While I have described this in earlier posts, the Unified Command have put out a video animation of the process, and there was an earlier diagram. So I am going to use these, which are simplified explanations, with some additional comments and tie it in to more facts that came out of briefings today, to try and give a more detailed explanation.
Animation here:
http://www.youtube.com/watch?v=v4YG7J-Ws6kBefore the process could begin, however, it was necessary to significantly modify the blow-out preventer (BOP) that sits on the top of the well. For those interested (its a bit like watching one of the operations on the space station) BP has assembled a short (5 minute) selection of the video footage of the various steps. When watching it, you should bear in mind that the ROV’s carrying out the different steps have to operate in a relatively crowded environment.
The tasks to be done included removing, modifying and replacing the control box (or pod) that operates the valves
that open and close the flow lines into the choke and kill lines on the well. Other than this, the flow lines to the flow and choke lines themselves had to be replaced with the feed lines (shown in the animation) that will carry the mud into the well. Even tightening a fitting that had worked loose takes time, when it has to be done using an ROV (with the operator at the surface needing to see what he is doing while getting the ROV to hold the necessary wrench and turn the fitting). The old feed lines then had to be cut from the BOP, and replaced.
Read more:
http://www.businessinsider.com/what-is-a-top-kill-2010-5#ixzz0oxccxp79