A Petroleum Engineer's Explanation

Originally posted by poet1b
reply to post by billyjack

 

Thanks for the reply. It seems clear to me that you have a excellent grasp of the subject.

I agree poet1b. I do have technical expertise in this subject having done engineering work on offshore drilling rigs in the Gulf of Mexico, and other places around the world, and I can confirm billyjack knows what he's talking about.

@billyjack, thanks for your excellent contribution in this thread. You really do know your stuff and I hope this will clear up a lot of misconceptions.

Like you I have wondered why they didn't handle some things differently like cutting off the riser sooner. I supposed they may have access to facts about the case that we don't have. But the bottom kill from the relief well should solve it eventually if they can hit the tiny target with the relief well.

I gathered that the BP executive dictated the riser would have the mud replaced with seawater against the objections of the toolpusher, so I have to wonder if maybe the toolpusher DID have evidence they shouldn't replace the mud with seawater? I wonder if he already had some clues the well was starting to blow out before they did that.

I also think you might be onto something with your comments about operational decisions being driven by accountants rather than operational experts.

Great thread, thanks again!

One thing that concerns me above all others is the fact that no seems to be accounting for the methane component of the leak.

OP, if the methane component comprises 40% of the volume flow by mass at the wellhead, how many cubic feet does that translate into by the time it reaches the surface?

I understand that natural processes (microbial action) converts the methane to CO2 and H2O by using oxygen in the water.

I have a read reports by the RV Pelican that:

The plume, which is roughly 20 miles (32 km) long, six miles (10 km) wide, and 100 feet (30 meters) thick, was discovered by the R.V. Pelican, a research ship, on its first mission.

Tests showed that about 30 percent of the oxygen in the plume has been depleted, which could threaten marine life -- mussels, clams, crabs, eels, jellyfish, shrimp and even sharks.

"It appears to be radiating from the spill site, so that's why we think it's a mixture of emulsified or dispersed oil, little oil fragments that are generated by the actual eruption of the fluid from the sea floor," Joye said in an interview with Reuters.

She said she was "99.8 percent sure" the plume, first spotted as "deep hydrographic anomalies", was spill-related and said it was quite possible that other, smaller, plumes existed.

www.alertnet.org...

OP, how big a cloud of methane is spreading from the leak do you think?

Thanks for the info so far, I really hope you can enlighten me about those questions.

reply to post by GorehoundLarry


This has happened before-in 1979, same location, same problem, same futile capping efforts, same environmental damage.
They stopped it back then with relief wells, which is what they are trying now. Looks like the IXTL all over again.
Maybe an 'accoustic switch' would have prevented this, however they are A)expensive and B)not mandatory. Since it's also the same company that owned the Ixtl rig, i am really surprised they haven't forseen this & made plans for it.
Logically, i could just put this down to bad management, if they did really pump the heavy fluid out, i find that a pretty stupid move.
I get 'experts' almost every day at my work, coming to me with the most INSANE ideas, devoid of any clear reasoning-other than that it looks good, and more often than not i have to tell them it's NOT a good idea, but they carry on regardless. I have even closed production lines & sent people home because of flagrant safety violations, not from the workers, but from the MANAGEMENTi am beginning to think it's part of the 'depoplulation programme'
Flagged & starred, in any case a good post.

[edit on 30-5-2010 by playswithmachines]

reply to post by apacheman

As billyjack said there isn't one leak but several of them. And we don't know how big they are, at least I don't. As one critic claimed they were watching a mouse while there was an elephant behind them (referring to the other leaks).

At least if they cut the riser they can hopefully reduce the number of leak sources.

This thing with the generators pulling methane into the intakes as the cause of the blast, I don' t think is plausible.

I do know control systems, and the generator diesels should have had safety systems in place that would have shut down the generators before they blew up. Overspeed, which is what the controls guy in the video describes, is one of those safety systems. I don't see how with modern safety control devices on diesel generators these generators could have blown up in this way. I also doubt that they could have generated that large of a blast.

Circuit breakers would have popped, and there were probable fuse in line as well. The only explosion would have came from the crankcase, and that would have been a minor explosion.

In addition, why wouldn't they have had someone on watch. Wouldn't this be a 24 hour operation. Someone should have been there to shutdown the generators in the remote possibility that safety systems malfunctioned. The way the controls guy describes this thing gong down is hard to believe, pretty much impossible.

Failsafe shut down would have have been required for this vessel and included shutting off the fuel, as well as the intake, which would have stopped the methane from running the generators out of control to the point where they blew up. Marine rated generators have even tighter safety standards. They had a blast door, but not the normal safety systems in place?

Preposterous!

I don't buy this theory that the generators took down the platform at all. They would have had to disable the safety systems, and I don't think a generator would create that great of a blast.

And of course all electrical systems have considerable safety systems put into place. With modern safety systems, these generators should not have blown up.

I think if the generators blew, it would have had to been sabotage.

reply to post by poet1b

Yes I would have thought they'd have overspeed controls in place. But if they malfunctioned......

I was reading William Stoner's testimony about overspeed and shutdown:

www.c-spanvideo.org...

00:18:02 WERE THERE SAFETY FUNCTIONS THAT WOULD SHUT IN AN ENGINE IF A GAS ALARM WENT OFF?
00:18:10 NOT AS FAR AS I KNOW.
00:18:14 EARLIER IN YOUR TEST MENNY YOU HEARD -- HOW LONG BEFORE THAT COMMUNICATION TOOK PLACE DID THE FIRST...
00:18:20 WASN'T BUT WITHIN A FEW SECONDS.
00:18:26 A FEW SECONDS. OKAY. DO YOU KNOW OF ANY SAFETY DEVICES ON THE ENGINES THAT WOULD PREVENT IT FROM ...
00:18:39 AS SOON AS IT STARTS OVERSPEEDING THAT GOVERNOR IS SUPPOSED TO GO AHEAD AND SHUT RIG SAVERS DOWN...
00:18:46 WHERE IS THE RIG SAVER LOCATED?
00:18:52 RIG SAVERS ARE UNDERNEATH THE TURBOS.
00:18:54 ESSENTIALLY WHAT WOULD THE RIG SAVER DO THAT WOULD ACTUALLY PREVENT --
00:18:57 IT'D CLOSE.
00:18:59 WHAT WOULD THE CLOSURE PREVENT FROM COMING IN.
00:19:03 SUCKING ANY GAS --
00:19:05 DO YOU KNOW IF THE RIG SAVER ACTIVATED? I WASN'T THERE.
00:19:06 ACTIVATED? I WASN'T THERE.
00:19:09 OKAY. ARE YOU WAYAWARE OF SAFETY DEVICES THAT AREN'T ON THE ENGINE THAT PREVENTED IT FROM RUNAWAY...
00:19:23 I MEAN, AS SOON AS THE ENGINE STARTED RUNNING UP AND STARTED THE LOWDOWN CHANGEOVER, IN OTHER WORDS,...
00:19:36 WHAT HAPPENS IF AN ENGINE RUNS AWAY IN THE PRESENCE OF GAS?
00:19:40 IT EXPLODES.
00:19:41 AND WHICH ENGINES WERE RUNNING AT THE TIME OF THE INCIDENT?
00:19:47 THREE AND SIX.
00:19:53 DO YOU KNOW WHICH -- IF IT WAS, THE EXPLOSION WAS A RESULT OF ONE OF THE ENGINES EXPLODING? WHAT?
00:19:57 OF ONE OF THE ENGINES EXPLODING? WHAT?
00:20:00 DO YOU KNOW IF ANY ONE OF THOSE EXPLOSIONS CAUSED THE EXPLOSION?
00:20:04 NO, SIR.
00:20:05 YOU DON'T KNOW?
00:20:09 I MEAN, I -- I'M NOT GOING TO SAY BECAUSE I CAN'T SAY FOR A FACT IT WAS THAT OR WHETHER IT WAS SOMETHING...
00:20:15 HOW DID THE ENGINE ROOM LOOKED WHEN YOU LEFT? WAS IT STILL IN TACT?
00:20:19 WELL, I WASN'T IN THE ENGINE ROOL ROOM. I WAS IN THE ENGINE CONTROL ROOM AND IT WAS TOTALLY DESTROYED.
00:20:33 WERE YOU AWARE OF ANY PROBLEMS WITH THE SHUTDOWN SAFETY DEVICES ON THE ENGINES PRIOR TO THE INCIDENT?
00:20:38 NO, SIR.
00:20:40 DO YOU KNOW WHO'S RESPONSIBLE FOR INSPECTING THOSE DEVICES?
00:20:48 WE DO -- P.M.s AND THEN THE E.T.s DO INSPECTIONS ALSO ON ANYTHING. IF THERE'S ANY KIND OF ALARM, ...
00:21:03 REPLACE IT. OKAY. AND DO YOU RECALL INSPECTING THOSE DEVICES IN THE RECENT PAST?
00:21:11 AS FAR AS I KNOW THERE WAS NOTHING WRONG WITH NUMBER THREE. WE JUST GOT THROUGH DOING QUITE A FEW...
00:21:18 OKAY. AT ANY TIME DID YOU RECEIVE ANY WORD FROM THE BRIDGE? OBVIOUSLY YOU HAD A RAID YOU THAT YOU...
00:21:38 NO. OKAY, THANK YOU.
00:21:41 IN YOUR TEST MENNY YOU SAID YOU HAD FIVE ESDs ON THE PANEL STARTED FLASHING. CAN YOU EXPLAIN WHAT...
00:21:54 WELL, I -- ALL I KNOW IS -- I KNOW -- I SAW THREE OF THEM. IT COULD HAVE BEEN FIVE.
00:21:59 OKAY.
00:22:02 BUT THE ESDs IS THE EMERGENCY SHUTDOWNS. IF YOU HAVE A FIRE OR SOMETHING TO THAT EFFECT IT SHUTS DOWN...
00:22:09 THE DAMP NERVES TO THE ENGINES?
00:22:12 GOING INTO THE ENGINE ROOM.
00:22:13 WHICH WOULD CUT OFF FUEL GOING INTO THE --
00:22:14 FUEL OR AIR.
00:22:17 -- OR GAS OR ANYTHING?
00:22:18 IT SHUT OFF MAINLY THE AIR GOING -- SO YOU AIN'T GOT THE AIR AND THE FUEL MIXTURE AND ALL THAT THERE....
00:22:25 WHERE WAS THAT PANEL LOCATED THAT YOU SAW THE FLASHING LIGHTS?
00:22:30 IT WAS JUST OVER WHERE, LIKE, IT'S ON THE -- IT WAS ON THE PORT WALL JUST SIDE THE PORT DOOR GOING...
00:22:41 SO IT WAS IN THE CONTROL ROOM?
00:22:42 YES, SIR.
00:22:44 WHERE THE DOORS BLEW IN? IT WAS IN THAT CONTROL ROOM?
00:22:46 YES, SIR.
00:22:48 IT STARTED -- DID YOU HEAR GAS ALARMS, ANYTHING FIRST? NO.
00:22:51 GAS ALARMS, ANYTHING FIRST? NO. JUST ALL THE FLASHING LIGHT. AND THEN YOU COULD SEE -- OR MORE OR LESS...
00:23:02 FROM YOUR KNOWLEDGE, WOULD THE ESD SYSTEM BE AUTOMATED THAT THESE WOULD FLASH AND THE AUTOMATION WOULD...
00:23:16 I DON'T UNDERSTAND WHAT --
00:23:18 IF THIS LIGHT WAS FLASHING, WOULD IT INDICATE IT'S TRYING TO SHUT SOMETHING DOWN? NO.
00:23:21 SHUT SOMETHING DOWN? NO. IT SEEMED TO ME LIKE IT -- SOMEBODY MAY HAVE TRIED PUSHING IT.
00:23:26 OKAY. SO IT'S A MANUAL -- SOME SORT OF MANUAL DEVICE SOMEBODY WOULD HAVE TO PUSH?
00:23:31 USUALLY IT'S -- SOMEBODY'S GOING TO PUSH A BUTTON TO SHUT SOMETHING DOWN TO TRY TO SAVE SOMETHING....
00:23:38 LIKE, IF IT SENSES A LOT OF GAS IN THE ROOM IT AUTOMATICALLY TRIPS THIS ESD? IT'S NOT AN AUTOMATION?...
00:23:49 AS FAR AS I KNOW YOU USUALLY JUST SHUT OR PUSH OR OPEN UP A LID ON IT, PUSHES THE BUTTON AND IT WILL...
00:24:01 OKAY.
00:24:03 I'M AN E.T.
00:24:05 DO YOU KNOW, IS THERE MORE THAN ONE PLACE TO PUSH THE ESD BUTTON? CAN YOU PUSH IT ON THE BRIDGE, ...
00:24:12 THREE PLACES YOU CAN PUSH IT OR COULD OPERATE IT. THE ENGINE CONTROL ROOM, THE BRIDGE, AND THE RIG...
00:24:23 BRIDGE AND THE RIG FLOOR. SO JUST FROM WHAT YOU SAW, I'M JUST TRYING TO SUMMARIZE HERE TO MAKE SURE...
00:24:39 I KNOW IT WASN'T THE ENGINE CONTROL ROOM.
00:24:41 PROBABLY THE BRIDGE OR RIG FLOOR.
00:24:43 I WOULD SAY EITHER BRIDGE OR RIG FLOOR.
00:24:44 OKAY. THANK YOU, SIR.
00:24:58 MR. STONER, HAVE YOU EVER PARTICIPATED IN TESTS ON THOSE ESDs?
00:25:03 NO, SIR.
00:25:04 NO? HAVE YOU EVER PARTICIPATED IN ANY TESTS ON THE OVERSPEED DEVICES?
00:25:10 NO, SIR..

The picture he paints isn't real clear.

[edit on 30-5-2010 by Arbitrageur]

I live 50 miles from the coast in Louisiana. We feel abandoned here with increasing fear that our state will soon become a dead zone. I fear Corexit is more of a danger than the oil itself from the information I have read in many of the threads. Could someone give me an idea of what coastal residents should expect if nuclear becomes the only alternative to stop leak. I can only see visions of more death and destruction if BP has to use this as a last resort. Should we prepare for a mass evacuation?

reply to post by Erica1631

They are actually drilling two relief wells for the bottom fill procedure. One of those should fix it. So I wouldn't worry about bombs until we see how the bottom fill procedure turns out. A bomb seems like an insanely bad idea to me, because there is some integrity in the upper part of the well that can help to contain it. If they destroy that integrity with a bomb, then we went from a solvable problem to an unsolvable problem.

reply to post by Erica1631


I don't want to be an alarmist, but pragmatism dictates that at the very least you should be making some contingency plans.

It certainly doesn't look like they'll be able to stop the leak before August at the earliest, and that's pretty optimistic, I think. Any hurricane that hits will definitely be spreading hydrocarbon-laden waters over a wide area with unknown but potentially hazardous health effects.

So you should think through where you would evacuate to when a hurricane hits, and plan on being there a lot longer than usual. If I were you I'd get with my neighbors and prepare an early evac plan and organize things like cooperative child care, who will represent your group/neighborhood during interactions with government entities.

This hurricane season is virtually guaranteed to be unlike any other in history, and shouldn't be approached in the same way as past ones. Look around you at the waters, listen to the fishermen's daily reports and talk where they gather and think through what will happen and what you'll do if oily water covers everything for miles around.

Without borrowing trouble, that's the most benign scenario I can think of, and IT sucks bigtime.

I must say providing you are what you say you are it goes to show how brilliantly diverse ATS is.

despite the techs for me this disaster is a culmination of seriously bad events that has seemed to shape the year of 2010.

This leak could have been avoid many ways, but it was not.

And it could have beens stopped by now if wanted, but it hasn't been stopped

And shores and wild life could have been much better protected, but again little.

The Government and military could have been more involved, but stay away.

And the clean up could be well under way, but it isn't.

So let me say again this oil spill was planned by the Illuminati to create anger world wide, to destroy the electrical charge of the oceans, to force the price of oil upwards, to bankrupt the people of the US, to render the Earth unable to make her leap in 2012, to dishearten the activists and environmentalists, to damage the dreams of whales and dolphins for a better world, make HAARP hurricanes even worse, to lower the vibration of the world another notch.

This much damage is easily worth a few billion for them.

reply to post by Arbitrageur


From this interview, it doesn't sound like the guy knows what he is talking about. I have never heard of an emergency shutdown system that relies on an operator to push some button. These systems are automatic, as they have to be. They also tend to be redundant, and I would think that such a vessel would have pneumatic controlled and powered shutdown systems as well as electrical.

If the flap that shuts off air to the intake is closed, it is held tightly closed by the powerful vacuum of the engine. It is an extremely effective way of shutting down such a system.

Also, I would expect there to be an LEL detection system would be independent, although possibly tied in to shut down the generators, or more likely trigger some additional safety features. Air handling systems are usually tied more to the Lower Explosive Limit system ( I think I am remembering these acronyms correctly) which is a system to monitor explosive gases.

I had always thought the explosion occurred in the pipeline that took down the drilling vessel. I find it hard to believe that the generators could have taken this out. Sounds more like a cover up.

I design and build control systems for most things that need to be controlled in the oil and gas industry. Engine controls, pump controls, processing facility control, etc. I haven't worked off shore. I've done some work in the Mississippi river delta down below Venice, LA (South Pass). I've seen everything from minimalist pneumatic shutdown systems to the max'd out gee whiz stuff that I program.

If the generator drivers didn't have two over speed shutdowns on it I will be surprised and if it didn't have one of the centrifugal over speed trips (mechanical device) on it I will be amazed. In fact I would say that someone had to have disabled / removed it if some form of over speed shutdown device didn't exist as well as an engine speed governor.

Woodward Governor, while not the only people in the business, are the defacto standard for engine speed control in the industry. The UG-8 is the one that I am most familiar with. If installed on the gen sets it would have started to reduce fuel to the engine almost immediately and as the speed climbed above set point it would have eventually shut the fuel to the engine off.

Gen sets have all kinds of controls on them. Engine controls to protect the engine. Generator controls to protect the generator. Generator controls to control the frequency and voltage of the generator output to protect the power users (electric motors, etc). There was very likely a mechanical over speed trip. There was very likely an electronic over speed trip associated with the tachometer. If the generator tried to run away the frequency would have increased to a point that it was out of spec and the gens would have tripped offline. Before that the freq controller would have tried to throttle the engine back via a signal to the governor however, the control loop for that is usually pretty slow. I can't say with certainty that the engine would have been shut down from a breaker tripping. Typically it happens that way but it's possible that wasn't the case in this instance.

On the topic of the transcript- I've been in 3 different bad situations (a fire, a ruptured discharge line on a compressor that was blowing condensate and gas toward 3 large engine driven pumps, and a boiler explosion that didn't kill anyone but nobody knows how it didn't). It's easy for someone that hasn't been there to grill that guy about whether or not anyone hit the ESD but unless it's on the way out (where would you go out there?) the ESD is very often the last thing that people think of and they damned sure don't get tested like they should.

Originally posted by poet1b
reply to post by Arbitrageur

 

From this interview, it doesn't sound like the guy knows what he is talking about. I have never heard of an emergency shutdown system that relies on an operator to push some button. These systems are automatic, as they have to be. They also tend to be redundant, and I would think that such a vessel would have pneumatic controlled and powered shutdown systems as well as electrical.

If the flap that shuts off air to the intake is closed, it is held tightly closed by the powerful vacuum of the engine. It is an extremely effective way of shutting down such a system.

Also, I would expect there to be an LEL detection system would be independent, although possibly tied in to shut down the generators, or more likely trigger some additional safety features. Air handling systems are usually tied more to the Lower Explosive Limit system ( I think I am remembering these acronyms correctly) which is a system to monitor explosive gases.

I had always thought the explosion occurred in the pipeline that took down the drilling vessel. I find it hard to believe that the generators could have taken this out. Sounds more like a cover up.

In 35 years of doing this I've never seen an ESD system that wasn't manual. I think too many people rely on electronic (PLC based) ESD systems and I generally put in a hardwired system, wired fail safe, and back it up with a PLC secondary system but the initiator is always a manual disconnect of some kind. It's pretty much a standard system in most places. The third level of protection is the control and equipment protection systems that are in place.

Offshore, as I understand it, gas detectors are a stand alone system that is designed to shut the platform down. Not so onshore. HOWEVER... what would gas detectors shut down? The BOP didn't work and it was the only level of protection. Once the gas kick started coming there was nothing to stop it. I suspect that the volume of gas on the floor increased so quickly that nothing had time to react. Gas detectors take seconds to react. They don't work instantaneously. In that time the gas cloud could have found a source of ignition... easily.

The air handler would have been protected from sucking in gas once the detector had time to react. Again, they react in seconds not instantaneously. Gas detections systems are also one of the most bypassed systems that I've seen. The detectors are finicky. They crap out all the time. They are expensive. They are a pain in the ass to calibrate. So guess what, the systems are always designed with bypass mechanisms and there is at least 1 out 3 or 4 bypassed on the systems that I've been around.

[edit on 5/30/2010 by Mike6158]

[edit on 5/30/2010 by Mike6158]

Edited for spelling and grammar... my English teachers came back from the grave and told me to fix them or something like that

[edit on 5/30/2010 by Mike6158]

Originally posted by Ethericplane
This leak could have been avoid many ways, but it was not.

And it could have beens stopped by now if wanted, but it hasn't been stopped

And shores and wild life could have been much better protected, but again little.

The Government and military could have been more involved, but stay away.

And the clean up could be well under way, but it isn't.

So let me say again this oil spill was planned by the Illuminati to create anger world wide, to destroy the electrical charge of the oceans, to force the price of oil upwards, to bankrupt the people of the US, to render the Earth unable to make her leap in 2012, to dishearten the activists and environmentalists, to damage the dreams of whales and dolphins for a better world, make HAARP hurricanes even worse, to lower the vibration of the world another notch.

This much damage is easily worth a few billion for them.

That's real neat and everything but did they happen to tell you how the leak could have been "avoid"? How it could have been stopped by now? How the shores and wildlife could have been better protected? Exactly what the government and military could have done considering one is only proficient at making a mess out of things and the other is the greatest in the world at "military stuff" and this disaster most definitely isn't military stuff?

Umm... the cleanup is under way where there is a cleanup needed. The hard part is going to be finding the "oil" (but that's a whole other topic)/

I'm bummed out about that whole earth not making the leap in 2012 thing... totally...

The American Association for Retired People cause hurricanes? And now they are makinf then worse??? Those bastards!

Originally posted by Mike6158
Offshore, as I understand it, gas detectors are a stand alone system that is designed to shut the platform down. Not so onshore. HOWEVER... what would gas detectors shut down? The BOP didn't work and it was the only level of protection. Once the gas kick started coming there was nothing to stop it. I suspect that the volume of gas on the floor increased so quickly that nothing had time to react. Gas detectors take seconds to react. They don't work instantaneously. In that time the gas cloud could have found a source of ignition... easily.

I think you nailed it. This gas kick wasn't some dribbling leakage, it was a snowball effect. As more gas filled the column, the column became lighter and allowed more gas to enter it more rapidly, which lightened the weight of the column even further. Once it starts happening it's a vicious cycle and without a functioning BOP to contain it, there was nothing to stop all that explosive gas from accumulating on the rig.

It's unclear what the ignition or explosion source was but it wouldn't take a runaway engine to explode, just the gas fumes getting sucked into the engine room and looking for an ignition source was enough to find one, that's also my take on it.

Somebody did hit the ESDs, but that was too late.

Originally posted by Arbitrageur

Originally posted by Mike6158
Offshore, as I understand it, gas detectors are a stand alone system that is designed to shut the platform down. Not so onshore. HOWEVER... what would gas detectors shut down? The BOP didn't work and it was the only level of protection. Once the gas kick started coming there was nothing to stop it. I suspect that the volume of gas on the floor increased so quickly that nothing had time to react. Gas detectors take seconds to react. They don't work instantaneously. In that time the gas cloud could have found a source of ignition... easily.

I think you nailed it. This gas kick wasn't some dribbling leakage, it was a snowball effect. As more gas filled the column, the column became lighter and allowed more gas to enter it more rapidly, which lightened the weight of the column even further. Once it starts happening it's a vicious cycle and without a functioning BOP to contain it, there was nothing to stop all that explosive gas from accumulating on the rig.

It's unclear what the ignition or explosion source was but it wouldn't take a runaway engine to explode, just the gas fumes getting sucked into the engine room and looking for an ignition source was enough to find one, that's also my take on it.

Somebody did hit the ESDs, but that was too late.

Its reasonable to believe that a generator would have tripped offline during an engine runaway and a generator tripping offline could have been the source. I've been around 480VAC and 13.8kV switchgear when it tripped offline and let me tell you it'll scare the hell out of you if you don't expect it. There's a lot of energy passing through a breaker under load, even in a little 600 amp breaker. They don't have arc chutes on them to redirect the arc when they disconnect for nothing. Google Arc Chute. There's a lot of info on them.

Back in the late '70's I was just out of school and working construction in an Exxon plant down near Milton, FL. The plant I&E tech had a real nice calibration room and he let me use it to calibrate transmitters before I installed them. It was winter, wet, cold, and nasty so I calibrated a lot of transmitters on that job

The calibration station had two primary pressure measuring devices. A mercury manometer for low pressure calibration in inches of mercury that he rarely used and a pneumatic Wallace and Tiernan gauge for higher pressure (0-30 psi). Both were accurate but the "wally box" was accurate to 1/10 of 1" of water pressure. I typically hooked the output side of the transmitter to one "wally box" and the process side to the other. There were all kinds of 3 way valves to direct the source pressure to various gauges and connection manifolds. The tech had always left the station set to both "wally boxes".

Bear with me... there's a reason I'm telling this otherwise boring story.

One morning I went in and started connecting a transmitter up to be calibrated. One line to the output. One line to the supply. On line to the process side. Normal procedure was to start turning the regulator knob until the reading on the "wally box" for the process side "moved". On this morning it didn't move like it usually did so I triple checked all of my connections, they were fine, and started again. I turned... and I turned.... and nothing. No reading. I checked again, everything looked good so I gave the regulator knob a little twist... all of the sudden there was a loud pop and crap started hitting the ceiling and falling all around me. I looked toward the pop and his big ole high dollar mercury manometer was emptying itself into my surroundings. I tried to shut the supply air off but it was over in a matter of seconds. I don't know how many pounds of mercury I blew all over that room but it was a lot. I started trying to "gather" it up but so much of it had atomized into fine droplets... It was everywhere. He came in right after it happened and saw me trying to gather it up. He started telling me how much money that stuff was worth and how he didn't have it in his budget to replace it and how they were going to bill the people that I worked for... It was not a cool situation. He disappeared and when he came back he had a big grin on his face and he was pushing a cart with no less than 3 gallons of mercury in a glass jar. Obviously this was during a time when the environmental initiatives weren't in place or the whole area would have been torn down, excavated, and hauled to a disposal area (to contaminate something else).

The point to this story was that I had over pressured the manometer. Once the first drop of mercury left the top of the column the rest followed. As the column grew lighter and lighter the rate of relief went higher and higher. Kind of like the blown out well... once they lightened the mud and that first kick hit it was all over... with no BOP to stop the flow of gas there was nothing to be done.

[edit on 5/30/2010 by Mike6158]

This is not directly connected to the current part of this discussion, but if they tried slowly pinching off the pipe stem above the sea bottom, I feel that there would be a very good chance, almost 100%, that it would launch the casing pipe out of the hole?
Without some seriously heavy mud in the pipe to balance the hydraulic force of the oil coming up, it would push the pipe up like turning on the pressure to a hydraulic cylinder with no load on it. I feel that is why they have not tried this technique yet.

Re the governor controls on the engines on the rig, if there is enough gas in the air to burn, and a diesel engine is sucking up, then it will continue to gain speed until it flies apart (read explodes) or the intake manifold is physically plugged off. I sometimes run boats with Detroit 2 cycle diesels, and they have the flap valve, similar to a swing check valve held open by a latch, that allows you to manually shut them down if they get oil in the intake because of a turbo shaft leak or any other reason and begin to run wild. They will burn any combustible fuel or oil that goes into the intake if there is plenty of air available, even with the fuel system shut down. That is why some diesel engines have a flap that can be closed over the air intake to shut the engine down in case it starts to run wild.
I wonder if the engines on the rig had this type of safety device on them. Many 4 cycle diesels do not, though it may be a requirement on offshore drilling rig engines.

A third thing to think about, suppose that there was a good sized hurricane which drove a huge part of a slick and the associated oil in the water ashore, then blew it all over everything. In a city situation, this could be a double disaster if a fire got started with everything soaked with fuel. Even if there was no fire, how long would it be before the people could safely live in that place again. Think Mobile, Panama City, Texas oil refinery ports, or any of the big coastal cities.

reply to post by MelonMusketeer

I posted the testimony from the motorman who said there's overspeed protection on the motor, but whether it worked or not is another question. He seemed pretty sure the motor would explode if the overspeed protection failed.

The casing could be cemented in place below the zone that's leaking. So I don't think they are too worried about the casing coming up. But they have plenty of other things to be worried about.