A day after saying that relief wells may not be needed, the government has decided that they are.
That's good news, as it greatly increases the odds that the oil well will permanently be capped.
Oil industry expert Robert Cavnar pointed out on July 14th - in arguing against the well integrity test - that there was a weak leak in the capping stack:
Today, Admiral Thad Allen said that the "spooling tool" was only rated to 7,500 psi, and that BP and the government are worried about blowing out that part:I'm sorry, but I have to ask, What the hell are they doing? We now have an ability to capture all the oil and stop this massive pollution of the Gulf (as well as measure it). We have great weather to get the relief well completed. We already know, without the "well integrity test", that they have severe damage to the BOP and other surface equipment and casing. If that weren't true, the damn thing wouldn't have blown out in the first place. We also know that between the "capping stack" and the old BOP that there is a non-wellhead rated piece of equipment, known as the flex joint, along with the riser adapter, that we've talked about before. This piece of equipment, that normally sits above the BOP, is not rated to nearly those pressures encountered by wellhead equipment. All of the other components in this BOP are rated to at least 10,000 psi (new, off the shelf, and undamaged); this piece is by far the weakest link in the chain, especially since it took severe stresses as the rig sank and 5,000 feet of riser torqued it as it sank. Yesterday, Adm. Allen announced they were going to take the stack, including this flex joint, to as high as 9,000 psi for up to 48 hours. I have been unable to learn the model and rating of the flex joint here, but Oil States advertises their LMRP flex joints to be rated 600-6,000 psi, far below the 9,000 to which Adm Allen said they would potentially go; even with the 2,200 psi of hydrostatic pressure on the outside of the competent caused by it being in 5,000 feet of water, it's still at least 1,000 psi differential pressure over the rating of the component.
Here's the full transcript from Admiral Allen's press briefing.
As Cavnar explained on July (using BP's illustration and explanation):
Here's a good illustration of the entire assembly:Because Cavnar and Allen name different - but adjoining - parts, I'm not sure whether it is actually one part or both the flex joint and the transition spool which are the weak leak.As you can see, the bottom spool of the assembly bolts up to the flex joint flange at the top of the BOP (blowout preventer).
But the bottom line is that BP has to be very careful when drilling the relief well.
And as I wrote on July 6th:
The team leader for BP’s relief wells – Boots and Coots – is 40 for 40 in successfully stopping oil spills using relief wells (around 6:10 into video).
Many oil drilling experts are hopeful that BP’s relief wells will succeed on the first try. I hope and pray that they do.
But the relief wells are not a slam dunk, especially at such extreme depths.
