Wednesday, June 02, 2010

"It's just a pipe."

From this article in the Times-Picayune:

Making his way to the BP table, Slidell resident John Sconza said he wanted to know why BP engineers haven't considered simply jamming something into the leak to plug it.

"It's just a pipe," he said.
I've been wondering the same thing. Could it be this simple? One has to assume that there is some good reason why this isn't possible; but, if not, I'd wish someone would explain why not.


Maitri said...

It's not that simple. It's a pipe coming out of the ground overlain by 5000 feet of hydrostatic stress and backed by very high lithostatic stress. You have to kill the well flow at the reservoir level and plug it with cement in order for the well to stay closed, not just throw heavy objects in there that have no adhesion qualities and expect it not to be shot out in seconds.

What works on land will not work here. And even on land you need a decent cement job.

eric said...

Part of the problem as I understand it is that, first, the oil and gas is leaking from multiple fractures along the pipeline, which necessitates cutting it off just above where it exits the ground. That's not as easy as it sounds, for a number of reasons. In fact, they started doing it this morning and their diamond-studded saw blade has already become stuck in the pipe (think of it like when you are cutting through a 2x4 with your circular saw with the saw positioned on the inside of two sawhorses... as the saw cuts through the board, the weight of the board bears down on both sides of the saw and eventually freezes up your blade... now imagine that 5000 feet underwater, with no sawhorses to control your leverage, and you have to operate the circular saw vertically via a remote control robot, while a huge jet of oil at incredible pressure keeps hitting your blade every time it starts to make a cut).

Now assuming they can even get this cut made so that they have a good place to attach some type of cap to, they have to make a decision: Do we want this cap to attempt to plug the well completely, which would require building one that can withhold tremendous pressure, at a depth for which such a plug has never been tested? What if there is damage downhole in the well casing? Then when you cap the well, the pressure will blow out joints in the pipe casing and cause oil to bubble up from the OUTSIDE of the pipe... how do you then take care of that problem? Potentially you just make it worse. I remember reading there was some pressure loss during the "top kill" procedure that seemed to indicate they were loosing mud somewhere down the pipe... a cracked casing would be a likely culprit.

No, it makes much more sense (Again, assuming you can can even get some type of cap on the pipe) to insert a cap that will let you capture and regulate the oil and gas pressure coming out of the pipe until the relief well is finished. You might still get some seepage into the water, but you have a greater measure of control than if you capped it and then your pipe starts cracking 200 feet downhole.

And, this appears to be exactly what BP is now attempting.