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Ltryptophan's avatar

Could BP's closing off the well create a hydraulic hammer?

Asked by Ltryptophan (10243points) July 19th, 2010

So I understand that when you suddenly shut off a fluid’s flow there is something that happens called a hydraulic hammer. It is like a massive shock wave within the fluid that rips apart its container.

Can this happen to the BP well?

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7 Answers

IchtheosaurusRex's avatar

That is why they closed the valves off gradually, to allow the pressure to build up slowly. Also – this is not entirely hydraulic. There is a considerable amount of methane in the flow, which unlike the oil is compressed as the pressure builds up. The leaks that have been a cause of concern since they capped off the flow are from methane.

Potentially, you have more of a blowout risk from the gas pressure than you do from the oil.

Ltryptophan's avatar

The government is hovering on whether or not to allow them to keep up the containment. They fear that the containment could cause a bigger problem. What is that bigger problem?

IchtheosaurusRex's avatar

@Ltryptophan , the bigger problem, as I understand it, is damage below the cap, in what’s left of the original blowout preventer, and in the well bore itself, which passes through thousands of feet of rock. Think of pinching off a garden hose. You stop water from flowing out of the end, but if there are weak spots or small holes in the hose itself, you risk rupturing it and having a flow that you can no longer control.

The cap can serve as either a collection or containment system. As a containment system, we would rely on it to stop the flow of oil altogether until the relief well is done. That would be ideal, but you run the risk of a leak in the system below it, a risk of the cap blowing off, or in the worst case, a buildup of pressure in the well bore that would blow out near the relief well. It would be better to open up the cap than to have those things happen, if you can capture all or most of the oil and siphon it to the surface.

john65pennington's avatar

That situation is far from over. capping one location is going to create another leak. the whole system is weak. i think the people at BP know this. the pressure is not being held with this capping. this can only mean there is another leak.

LuckyGuy's avatar

They are talking about pressure readings of 6750 psi instead of 7500 psi. Just out of curiosity I clacualted the pressure of seawater at 5000 ft, the depth of the well. It comes to 2200 psi.

Those are huge (scary) pressure differentials.

ETpro's avatar

No. They did not suddenly shut it off. THey slowly closed one after another valve monitoring the internal pressure all the while to see if there might be a sudden pressure drop, which would indivcate a new leak somewhere outside the well head.

Keeping the valves closed though, instead of attaching lines to them and beginning again to capture the oil is a bad idea. If there is oil leaking outside the well casing and beginning to penetrate fissures in the surrounding rock, long term closure could result in a rupture through the sea bad and there might be no reasonable way to stop that without simply letting the entire well deplete itself. That would mean the Gulf of Mexico would be a dead zone for a century or more and would cause mass extinctions of thousands of Atlantic marine species as well as oil picked up in the gulf stream and spread throughout the Atlantic.

Ltryptophan's avatar

@ETpro PEAR FAKE TOW…si

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