As discussed in my earlier blog entry, BP is preparing to install a new cap on the blowout preventer stack creating a double-decker BOP stack. Admiral Allen announced the government's approval of this process to be run simultaneously with the connection of the Helix Producer to the kill line of the original BOP.
Here is a picture of the proposed arrangement of ships and here is a picture of the new capping stack BOP. Starting at the bottom of the capping stack BOP you can see the "test pipe" which simulates the riser flange on the existing BOP that will be taken apart to make the switch. Above that is the spool piece, which provides a spacer to extend past the end of the drill pipes (Admiral Allen indicated that there are two, the one stuck in the shear ram and another which apparently fell when the rig sank. If you go to slide 4 you can see the mock up of what they expect to find when they remove the LMRP cap.) They will band those two pipes together before installing the spool piece. The spool piece has a quick connect "mule shoe" which mates with a hydraulic adapter on the capping BOP, which simplifies the process of making that connection.
The plan is to start removing the existing cap that is leaking (the star of the underwater video feeds) on Saturday. While it is being changed, the oil currently being collected by the Discoverer Enterprise will escape into the gulf. To mitigate that increased leak rate, the Helix Producer will be connected to the kill line of the original BOP and will start producing oil Sunday (if all goes to schedule) with the prospect of being able to totally supplant the current production through the leaky cap (about 15,000 barrels per day) plus an additional amount, bringing the total for that ship to 25,000 barrels per day. The hope is to have the capping BOP operational in 3-4 days. If all goes to plan, the leak will be stopped at that time (next Wednesday).
There have been some concerns about the structural integrity of the well casing. By closing the new BOP, they can allow the pressure to build to verify the integrity of the casing by slowing the rate they produce oil into the ships at the surface. If the pressure holds indicating that the casing is good, they can shut in the well. If it is suspect, they will lower the pressure at the wellhead by upping the rate they produce the oil and wait until the relief well can be used to bottom kill the well. As an added benefit, the new cap makes the bottom kill much easier as it precludes the escape of the drilling mud through the leaky cap, as was so visible during the abortive top kill procedure. The combined wells would both be tight up to the sea surface, instead of the relief well being a mile above the leaky cap on the wild well. That is obviously a better circumstance than pumping in mud on the surface and letting it leak out at the mud line a mile below.
So BP has the equipment in place and a spell of good weather to work on finally controlling the well. I'm sure we all wish them Godspeed!
Bruce Thompson
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