There is not much published on the web about these gadgets. They were invented in the 1920's and they ended the "gusher". You must have seen a picture of black oil spurting up higher than the top of the drill rig. The movie "Giant" with Jimmy Dean as oil wildcatter Jett Rink had a great gusher scene, black goop falling like rain.
The blowout preventer is a VERY strong valve that sits on the top of the well and shuts off the oil flow. Just how they work, above ground or underwater, was not made clear. It is implied, (but not outright stated) that they work by squeezing the steel drill pipe shut. Presumably this requires a power source (hydraulic? electric? compressed air? explosives? ) to work the pipe crushing ram. Also presumably activating the blow out preventer is an emergency measure since it damages the drill pipe, requiring replacement of the section of pipe the preventer squeezed flat. Also, presumably, the blow out preventer only succeeds in shutting off the oil flow when the drill pipe remains more or less intact.
Questions for BP. How was the blow out preventer powered one mile under water? Did the power come down from the floating platform that exploded and sank? How was the signal to actuate the preventer carried down under water? Was there any redundancy in case water got into the wiring or a pipe sprang a leak? Was the actuation automatic, like a fire alarm? Or was it the duty of the watch officer to flip a switch in the control room? What sort of protections against accidental actuation of the blow out preventer were there? What was the name of the watch officer responsible? Did this individual survive the fire and explosion that sank the platform?
More questions. Can the preventer be actuated by a submarine? What equipment does the sub need to carry? If the power supply is sunk, or run down (batteries, or compressed air tanks) can the sub recharge it? Is there a backup actuater such as a big hand crank? If so, can a sub work it?
And more questions. Who sold the blow out preventer? Was it new or used? Is that model rated strong enough to handle a well that deep? Who inspected the blowout preventer before it was installed one mile under water? What are the inspection requirements? Cracks? Leaks? Fully charged batteries or air tanks? functional control circuits? Are there any inspection requirements once the blow out preventer is under water? If so, did BP carry them out?
These are all questions that educated and experienced news men would ask. Unfortunately newsies these days are neither educated nor experienced.
7 comments:
Some very insightful comments. As a mechnical engineer at a nuclear power plant I am very interested in the level of "diversity and redundancy" in these BOPs. IE. at a nuke plan we have 2 sets of identical systems such that these systems are "single failure proof". Additionally there are backup systems that are of different design & use different types of power sources such that an undiscovered design deficiency in the primary safety systems would not also affect back-up systems. the diversity was emphasized after TMI and I think has really decreased the potenital for a significant accident. I wonder if this same philospophy is or will be implemented in the offshore drilling industry. I believe this is their three mile island as the Valdez was to the shipping industry
The most discouraging thing is, with the exception of the Wall St Journal, the complete lack of coverage from the "Main Stream Media". Either they don't care, or more likely, they are too clueless to ask meaningful questions.
Poor post all around and very premature, maybe a little bit more appropriate in a year (or two).
Your questions are constructed obviously from someone who has zero knowledge of the industry and it shows. Your questions are not "meaningful" but just silly to make assumptions that such a large company regulated so heavily (especially in health and safety) would even consider things like "reconditioned" BOPs. Safety devices industry wide always Fail-Safe. Not fail-blowup like you would "assume". Systems like this are extremely redundant and go through heavy testing prior to commissioning. An event to cause such serious damage to sink an entire platform and every safety initiave put into it is obviously a catastrophic unforeseeable problem.
"Either they don't care, or more likely, they are too clueless to ask meaningful questions." This truly must be a joke? How about the questions like "What's their plan on stopping this?" wouldn't that be a far more meaningful question? The investigation to why this happened is clearly going to take YEARS. Your thoughts on why they aren't asking such technical questions while the thing is still leaking oil clearly shows you have a complete lack of understanding on how technical an operation like this is.
This is going to cost them upwards of 7 billion dollars to clean up and take care of. That's not including the increase in cost of global operations because of it (insurance, WCB, ect). It's a poor assumption to think they didn't know this prior to it happening and didn't invest huge sums of money to make sure it wouldn't happen. The fact that it did only goes to show how extremely difficult the task is.
Personally I think you Americans shouldn't even allow them to drill in these areas. Why don't you blog about that instead, it might be a better use of your time. Or maybe you're one of those chanting "Drill Baby Drill" at the Sarah Palin rallies.
David, some good questions. I'll try to answer some.
A blowout preventer (or BOP) is basically a valve that sits at the top of the well during drilling.
It fully opens to allow the bit and drill pipe to pass through it, and it has to close and seal even with pipe in the hole.
The most important type is the ram-type. It's like a gate valve, except the gate is split into two halves. Each gate is moved in and out of the bore of the tool by hydraulic cylinders mounted on the side. Land BOP's sometimes have a mechanically actuated closing mechanism, but it's not practical for BOP's mounted on the ocean bottom.
A BOP "stack" usually has several ram BOP's. Some of them will be fitted with "blind" rams, that will close the well when there is no pipe in it. Other rams have openings so that the rams close around the pipe. That prevents well fluids from flowing up past the pipe, but still allows the flow inside. That's usually okay because there is (usually) other pressure control equipment above the DP.
However, at least one BOP is fitted with "shear rams". These are made to cut the pipe, almost like a pair of scissors, and make a seal in any circumstances.
The BOP's are operated by hydraulic fluid. On a deepwater well, the BOP's are mounted in a frame that also holds other equipment. This includes steel bottles with reserve hydraulic fluid under pressure, usually 3000 or 5000 psi. There should be enough reserve capacity to operate all the rams several times.
I don't know details, but the BOP stack also included a way to pressurize the hydraulic fluid, probably electrically driven pumps (powered by the electrical supply on the rig, driven by large diesel engines). There will be batteries to operate valves and the control system. Control systems are normally considered very reliable, and a lot of engineering (and $$) goes into them.
There are redundant systems to make sure that the command to close one or more rams actually work. One article I read said that the surface crew sent the command, and saw a green light indicating that the BOP had closed.
The ROV's that have been sent down would normally use their robot arms to operate valves and close the BOP. BP has not given any details except that it didn't work.
Some speculate that the BOP didn't close all the way, and that the flow eroded the rams to the point where they are useless. Sounds very possible.
BOP's themselves are simple, big, heavy tools. The rams and the seals need to be maintained, but in normal use the body can last for many years. Basic body styles haven't changed much in decades. The failure was probably in the control system.
Actually, that was just one of several failures. The first one was probably a poorly designed or executed cement job that allowed flammable fluids (probably gas) to enter the well bore, where it rose to the surface and caused an explosion. Even then, the problem should have been clear during testing, and the BOP stack should have controlled it.
Do a web search for "BOP stack", and you'll see lots of good results, including pictures that should explain a lot.
Another blog pointed out that the people who work on a rig usually work for several different companies, not just BP and Transocean. So they really don't have any motifivation to hide anything. I suspect that they are not talking much, but that we'll eventually hear most of these details.
BTW, there are excellent discussions of this taking place at this site:
http://www.theoildrum.com/
P.S. Oil professional, this blogger didn't claim to be an expert or a professional journalist. And not everybody in the US thinks highly of Sarah Palin (she lost the election, remember?).
A true fail-safe valve would close itself without any intervention or control. It would be CLOSED at all times UNLESS held open by a control system e.g. hydraulic pressure, water pressure, and valves, control system etc. if ANY of those system fails, even a power outage, the valve would CLOSE ITSELF. I see these valves as old throwbacks to the oil industry of the past. The basic designs are totally obsolete. For off shore drilling a completely fail-safe valve is required, and the oil industry does not appear to have one.
Marsolian, Thank you for some interesting information. Since posting this, I have seen the phrase " shear rams" in a couple of places. If the shear rams just snip off the pipe and stay closed to shut off the oil, then is there not a lot of pressure from the drill pipe trying to push the rams away from the pipe and let the oil squirt out?
Does the blowout prevent rely on its weight to hold it in place, or does it grab onto the drill pipe somehow?
The argument that allowed BP to drill in the gulf was that The Company would act in its own best interest according to its own profit motive. They then pointed out that they have some of the best scientists, engineers and oil rig experts in world, Therefore they would be able to drill safely at depths that far exceeded any than had been attempted before. This argument proved to be false. As a country we need responsible government regulation. Companies rise and fall and their only constant function is to make as much money as they can. By design companies have no responsibility to humanity, society , loyalty or the future any more than it serves its own interest. In order for this country to prosper in the future and pay off the national dept, we need to audit our relationship with every huge cooperation and make sure those relationships are responsible and fair.
http://www.sunflowerpipes.com
Post a Comment