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What would it take to avoid sinking the platform?
2

What would it take to avoid sinking the platform?

What would it take to avoid sinking the platform?

(OP)
Seems like just a little extra steel between the underwater pontoons would do it.  Then, of course, we would need a tugboat nearby to keep the rig from drifting off and snapping the riser.

RE: What would it take to avoid sinking the platform?

That brings up a question that I have wondered about. Why did the rig sink. Fire damage to the structure? Malfunctioning bouyancy controls as a result of the fire, or was it pulled down by the still connected riser as it drifted off station?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

I'd be surprised if the marine riser pulled it down, as the rig (not a platform by the way- a platform stands on the seabed) usually supports it.  And don't forget, docellen, that the Deepwater Horizon was a dynamically postioned rig (no anchors) - so you wouldn't need a tugboat to keep it on station, just larger thrusters on the DP system.

I'd suggest the most likely reason it sank is that a massive fire that lasted for about 3 days resulted in a loss of structural integrity?

 

RE: What would it take to avoid sinking the platform?

Thanks Nic. The reason I suggested the riser is that I understand that the riser never disconnected as it was supposed to. Was the fire fed by fuel already present on the rig or did the riser feed the fire right to the end?
Was any power restored, or were the generators still out and the rig drifting for three days?  

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

(OP)
The fire would burn out quickly without continuous feed from the riser.  Even if all the steel melted, the underwater pontoons should still be floating.  I'm wondering if the fire fighters made a colossal mistake, and deliberately sank it.  Maybe in all the confusion, they didn't think to ask if sinking it would be a good idea.  It wouldn't take 3 days for the steel to get hot.

I sure wish BP would be more open with technical information.

RE: What would it take to avoid sinking the platform?

Too much firewater tends to destroy positive buoyancy.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying."  Tony Hayward CEO BP
"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

RE: What would it take to avoid sinking the platform?

(OP)
But how does that water get inside the pontoons.  I suppose it is remotely possible a piece of steel fell like an arrow and penetrated the pontoon underwater.  Maybe with one pontoon out, the entire rig would sink.
 

RE: What would it take to avoid sinking the platform?

the rig got flooded,the pontoons are designed to give the rig enough buyoncy, its not designed to fill the rig up with water.

RE: What would it take to avoid sinking the platform?

This is not the first vessel to be sunk by to much fire fighting water. Did no one figure this out or was the sinking intentional.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

Oil rig fires can get pretty hot- hot enough for steel to loose it's integrity (not to melt- just loose enough strength that the structure collapses).  Look at what was remained of the Piper afer it had burnt for a day- only the wellhead module (held up by 24 wells) was left...

RE: What would it take to avoid sinking the platform?

(OP)
How about adding a diverter at the top of the riser to keep the oil and gas shooting in a safe direction, away from the rig?  Maybe even put this underwater, so there is very little chance of the fire even starting.

RE: What would it take to avoid sinking the platform?

In normal operation the riser must allow the free flow of the return mud.
The fire probably started when the mixtuire of methane gas and air ignited. The military would call this a "fuel-air bomb".  
Two possible issues with an underwater discharge.
This may lead to an enormous buildup of a methane-air mix that may eventually reach the rig and explode. It has been stated that the larges explosions possible short of neuclear are air-fuel mixes. The largest peacetime explosion in Europe was a fuel air explosion resulting from gasoline vapours when a fuel storage tank overflowed, and the spilling gasoline mixed with air. Ironically, it may have been ignited by a spark from the fire alarm system.
An underwater diversion would probably require some type of control or valving so that the mud could return in normal operation.
I suggest that rather than major modifications to the BOP design, (so it won't shear a drill stem joint? In a functioning BOP there are two shears positioned so that joints are not able to obstruct both at the same time.)  The drilling culture of some companies must be changed so that work follows best practice and safety equipment is maintained in operating order at all times.
In addition, it is starting to look as if the failure of the BOP may have averted a worse environmental disaster. I understand that there is now reluctance to stop the flow for fear that the casing may rupture below the sea floor and release even greater amounts of oil at random locations. There have been suggestions that this may have already happened and restricting the flow at the BOP will make this situation worse.
An analogy;
In North America, large transport trucks have an emergency braking and parking system that is applied by springs and released by air pressure. If an air line breaks in this system the brakes are applied automatically. It is possible to release these brakes manually so that the rig may be moved for short distances, eg; off the highway. It is illegal to drive on the highway with this system disabled, even though the service brakes will still work normally.
If there is a broken line in the trailer brake system, the trailer brakes will be applied automatically with reservoir pressure, and should this fail the spring brakes will apply automatically. The trailer reservoirs may be exhausted and the system isolated and the spring brakes "Cranked off" and the rig may be moved and stopped with the truck service brakes. At this point, the braking force may be less than half of normal. But the truck is still capable of being driven at normal speeds, it just doesn't stop very well.
Now suppose that the driver of a "Super B train"  (Two trailers has a problem with his trailer brakes and disables them. He had brakes on 14 dual tired wheels. Now he has brakes on only 4 dual tired wheels. His initial braking force will be 4/14 or 29%. A panic stop from highway speed mayquickly overheat the remaining brakes and result in less than 10% of normal breaking force.
Now, if a driver has problems on the road and, in order to save time, disables his trailer brakes and drives at normal speed and then has a horrendous wreck, do we blame the driver and possibly his supervisor, or do we redesign the braking systems of all the trucks in North America?
Wouldn't happen? Look at the accident reports for brake failures due to simple neglect in the mountains of Western Canada.   

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

(OP)
The diverter I'm thinking of wouldn't require redesign of all trucks in North America.  In fact it would hardly cost anything, compared to the cost of a BOP.  It wouldn't be 100% effective.  If there is no wind, the gas could still accumulate around the rig.  Still, I would rather have this than nothing.  Remember it is a backup system.  The main line of defense should be early detection of a kick.

The more I learn about this disaster, the more I am convinced that some simple, low-cost engineering will greatly improve safety.  Have you ever been in a missile silo?  It takes two guys with keys, standing at opposite ends of the room, or the missile won't launch.  I can imagine a system that not only has automatic shutoff when the mud flow is imbalanced, but requires two guys with their hands on the controls to keep the auto shutoff from activating.

Safety culture is important.  Engineering can make it easy.

RE: What would it take to avoid sinking the platform?

The point that I am trying to make is that this is not so much an equipment failure as a human failure on the part of bp.
You could have 12 people holding buttons to hold off the safeties. When one of them decides to activate, it doesn't matter if the annular seal won't work because it was damaged and not repaired. It doesn't matter if the second annular seal has been turned off. It doesn't matter if there is not enough hydraulic pressure to activate the rams.
I imagine that it may be time to consider designing shears that are tough enough to shear a coupling, but that still won't help is there is a hydraulic leak and the system has been turned off.
This is not a hardware problem. It is a people problem.
 

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

(OP)
I agree, the problems leading to the current disaster are mostly human failures, but I just wouldn't go so far as to say it is not at all a problem that engineers can help fix.  There are plenty of things we can do to improve the design.  To use your examples, damaged seals, low hydraulic pressure, etc., how about we add a data logging device, like many cars have now, that records the results of regular testing on the BOP.  If any of the above problems were to occur, it would show up as a record of excessive flow during a pressure test.  How about we add a computer interface, so inspectors can query the data any time the have doubts that a test was done.

Yes, I know, clever humans could figure out a way to disable the recorder, but that is a lot less likely than the current "failure mode", where people just forget to do any tests.

RE: What would it take to avoid sinking the platform?

Docellen- a diverter is commonly used on floating rigs while you are drilling surface hole, before the BOP is estabilished (you have to get to a certain depth to provide a strong enough foundation for the BOP).

A diverter is typically a 3000psi rated annular and immeditely below it the riser has two side outlets with interlocked valves on each.  These side outlets go overboard to each side of the rig.  The diverter actuated, and the annular closes and one of the side outlet valves is opened to divert any flow to the downwide side of the platform, hopefully giving everyone enough time to get to muster and get off the rig.

A diverter is the defence against "shallow gas" thin, isolated pockets of gas in the top 500ft or so of sediment.  Shallow gas scares the shit out of the offshore drilling industry because it is so dangerous- as well as the fact that there isn't a BOP, there's also the issue of loss of bouyancy due to the gas in the water column-  there's a famous and terrifying video clip of (I think) the Sedco 711 fractically trying to get off station while the sea 'boils' around it... you can see the entire rig listing badly as it looses bouyancy on one side.  The issue of loss of bouyancy is the main resistance to the idea of subsea diverters (which have been suggested).  

So, traditionally, once the subsea BOP was on the wellhead and tested, everything was OK, as the BOP would always work- 100% redundancy on the separate rams and annulars, 100% redundancy on the control systems, and then 100% redundancy on the emergency control systems (when I started drilling 15 years ago emergency BOP control systems weren't really known).  This is what everyone I talk in drilling to wants to know: why did the Deepwater Horizon's BOP fail????

A diverter as well as the BOP might become law; but remember that everyone except the guys on the drill floor and pump room got off the Deepwater Express, and that the gas bubble would still have arrived at the surface if the rig had had a diverter as well as the subsea BOP (they didn't shut the well in when there were indications that the well was starting to flow 20 mins before the explosion, so I doubt they would have shut a diverter either).  Finding out why the gas exploded when everything is supposed to be EXd zone rated would be a better solution.

I was chatting about this to a guy who is now an OIM on a North Sea platform (I wont't say which one) and he said that in the 80's this platform had a gas leak: 3,000,000scf.  The only thing that stopped it being a second Piper was the gas was above the Upper Explosion Limit, and the production techs had enough time to cut off all electrical power to the entire platform.  In the internal investigation afterwards, they realised that almost all the lighting in the accomdation block and even some of the lighting outside in the drilling and production modules was just bare wire connections.....

RE: What would it take to avoid sinking the platform?

(OP)
I sure wish we had a diagram of the BOP.  That would answer a lot of questions about redundancy.  My guess is there is some common factor, like a single hydraulic supply that got low on pressure, due to a slow leak that was ignored.  That would explain why all the rams seem to be working, holding off some pressure at each ram, but none are fully closed.

BP has released a detailed diagram of the externals (see http://energy.gov/open/oilspilldata.htm) but that doesn't help with questions about the hydraulics, redundant connectors, etc.

I can't find any diagram of a diverter.  Seems to me it should be entirely passive, not requiring anything to be actuated.

Finding the exact cause of the BOP failure may take months.  I think we already know enough, however, to move ahead with fixing the human-factor problems, and improving the design of the wellhead, BOP, and rig.  The improvements I have on my list could be done even before all the investigations are finished.

RE: What would it take to avoid sinking the platform?

docellen,I contacted BP requesting detailed drawings of the BOP.their answer:thank you for your questions,blablabla..., we do not have time to answer them
my conclusion:
main reason to establish communication between BP and public is not to provide or to get information but to polish
BP's image towards the public

RE: What would it take to avoid sinking the platform?

(OP)
Perhaps someone on this forum has access to a manual, or knows someone who does.

RE: What would it take to avoid sinking the platform?

To answer the original question - there IS steel between the pontoons to hold the rig together as well as the deck. These and the deck box are what keeps the two pontoons together.

Although hot fires like this can weaken the steel (like the derrick, for example) it does not seem the immediate reason for the sinking. Her deck box did not seem to fall apart and then the rig sink.

The final moments of the rig on the surface did seem to include noises of structural failure. But by that stage she was laying over at a considerable angle and low in the water. That angle could have helped things start to break loose.

The only way she got into that attitude was because she lost buoyancy or there was more water/oil in her than at the start of the incident. The latter could have happened for one or two reasons;

1) oil or water or both finding their way down into the rig columns or pontoons (or even into the deck box). This should not normally happen for the same reason the rig does not fill up in heavy rain. But the explosions probably opened up paths into the previously water/weathertight structure. In fact, oil/water gathering in the deck box would be worse for stability than oil water running below into the pontoons/columns.

2) ballast flooding into previously empty tanks because of ballast valves opened to the sea by destroyed ballast control system (SHOULD not happen due to fail safe ship side valves, but who knows what was actually installed)

RE: What would it take to avoid sinking the platform?

(OP)
JR, excellent answer.  It raises another question, however.  Why would either the deck box or columns not simply drain whatever water came in?  Are the pontoons close enough to the water surface that they could be ruptured by an explosion?

I think your guess about the ballast valves not being a fail-safe design is the most likely reason.

We need an emergency connector, accessible from a boat even with the rig on fire, connected to ballast valves, underwater thrusters, and whatever else is needed to maintain minimum control in an emergency.

RE: What would it take to avoid sinking the platform?

Normally the deck box will have scuppers etc to drain any water over the side. But as I said, this integrity was probably breached by the explosions, allowing liquid into spaces normally dry. Allowing 10,000 tonnes of liquid into the deck box would be more dangerous for stability than allowing 10,000t into the pontoons. It would flow to one side, causing a heel angle. Then when the heel angle gets bit enough, the sea starts to flood in through external openings, and that is the end of the story.

The pontoons are not so close to the water surface, and if they had been breached by the original explosions, then the listing and sinking would have been quicker than seemed to be the case. In addition, the pontoons consist mainly of ballast tanks, which are mostly already full when at drilling draught.

Breach of a column at/below the waterline and its flooding would be more easy to imagine, and this would lead to a heel angle problem. The columns are what gives the vessel its "stability" on the surface, whereas the pontoons main purpose is to give weight carrying apacity (Archimedes principle).

As for the ballast valves, this was a modern rig and I would expect the ship side valves to be fail-to-closed rather than fail-to-open. This is certainly a requirement in the UK since the 1980s. The loss of OCEAN RANGER offshore Canada was one reason for this requirement.

RE: What would it take to avoid sinking the platform?

Docellen

Re your question/suggestion about an emergency connection which would allow thrusters etc to be maintained following such an event..........

You are certainly right in wishing for some means of keeping the rig in position after such an event. But the power generation, distribution and control systems on these DP rigs are so complex, attempting to do it via the existing thrusters is impossible. To take one simple example the day tanks (service tanks) in the fuel supply system would need topping up from the storage tanks within a day or so.

It would be easier to ensure there are some deployable (but how ?) towing bridles that would allow support tugs to hook up and hold the rig without men having to go onboard.

While on this subject, I read on this forum some folk making remarks about the fact that the generators were breathing methane and should have had shut down flaps to prevent this.

Since this was a large modern DP rig, dependent on engine power for positioning (a.k.a avoidance of riser rupture) I would expect the following to have been present in her design;

1) automatically actuated fire flaps on the engine room air intakes, linked to the fire and gas, emergency shutdown matrix, to avoid gas ingress to the ignition sources in the engine room in case of gas detection

2) engine room air intake DIRECT DUCTED from the outside into the turbo intake on the generator - specifically to ensure that the engines WOULD continue to run and the rig not drift off (risking the riser) in the event of a gas leak (when engine room intakes closed, hopefully)

And finally, whatever the failings of BP on this rig or in their former ARCO/AMOCO refineries ashore, the responsibility for properly maintaining the rig's explosion proof equipment and the ESD fuctions on air intakes etc was not theirs (as some seem to think).  

RE: What would it take to avoid sinking the platform?

Sorry Docellen - I realised that I did not properly answer your question about why the deck box would not drain any water/oil that came INTO it.

The scuppers would drain off oil/water that came ONTO it.

The deck box would not let water/oil out that came IN because it was designed to be watertight (from the outside). The buoyancy in an intact deck box is one of the things that stops the rig heeling too far in a damage incident (like loss of a column).

The underside of the deck box would have been totally watertight. When you get to the top of the deckbox you cannot avoid all sorts of penetrations (doors, vents etc) that may or not be watertight or resistant against flooding when the rig reaches an extreme angle and the water comes over them.

RE: What would it take to avoid sinking the platform?

JRMacGregor,
consider the amount of power a platform uses
consider the volume of air required to power the diesels
shut down flaps with gasdetectors on the engine room air intake will pull the engine room in vacuum and black out the rig, so no more thrusters, just the emergency fire pump
running on the emergency diesel, maybe
consider a blowout of methane,the rig completely surrendered by a cloud of the right mixture of methane and air.by the time the gas detetors on the air intake work, the engine room is filled with methane/air
direct ductig of turbos is not done, you would pull to much salt in your engine, in case of gas leak, you still overspeed them on the methane/air mixture
remember the BOP was the last line of defence, a triple redundant device (on paper)
1 annular device, shred to pieces while performing normal operations
2&3 failed to operate (did they?)
the maximum pressure they have to withstand is the well pressure plus a safety margin (really?)
static force=well pressure (this you could simulate and therefore test
dynamic force=bringing a 15km long liquid flow to a sudden stop.its like trying to stop a runaway train by placing a truck in front of it.

RE: What would it take to avoid sinking the platform?

No - that is exactly my point.

The engine combustion "air" has a separate duct from the outside. If the engine ROOM fire flaps are closed the engine can continue to run.

Direct ducting of engines IS done - I have built DP drilling rigs.

RE: What would it take to avoid sinking the platform?

(OP)
JR,  your knowledge and experience is greatly appreciated.  If I understand correctly, a little extra steel between the pontoons won't help.  That part of the structure is already strong enough.  The problem is in the columns (which must be buoyant to keep the platform level), and the deck box (which must be buoyant to avoid rollover if the columns are damaged).

At this point, I can only state a general requirement, not a specific solution.  The rig must not sink after a blowout and explosion.  Specific solutions might include having separate compartments in the deck box, so they don't all flood when there is limited damage, or maybe having inflatable pontoons in a strong box under the deck.

Another solution might be to let the rig sink, but have separate flotation for the top of the riser.    Maybe this could be a big collar with rings that could be hooked to winches on a nearby ship.  

There must be a simple solution that doesn't require readiness and planning that may not be there 20 years from now.

RE: What would it take to avoid sinking the platform?

The emergency shutdown flaps in a diesel are installed at the air intake intake of the engine. The original application that I know of was in the two cycle diesel engines built by General Motors, Detroit Diesel Division. Probably the best known of these was the 6-71 model Detroit Diesel. When these engines were first built back in the 30's oil seals were made of leather. Failures were common. A failure in a shaft seal in the blower would allow engine lube oil to enter the blower and intake manifold. The engine would start to run away and could fail catastrophically due to high speed. Today in Canada shut down flaps are common in diesel vehicles used in petroleum facilities from rigs to refineries and upgraders. This is not new technology. Intake flaps on diesels have been around for over 70 years.
Regarding dampers in the ducting to the engine room. Maybe not a good idea. There have been failures in the dampers of HVAC mixing systems that closed both the return air and makeup air ducts with the fans running with the result that the plenums collapsed due to reduced internal pressure.
And a friend once told of being in a standby generator room for a startup where the air intake dampers to the room had been wrongly installed. Common practice at that time was to use a spring return damper motor to hold the air intake flaps clopsed. When the ATS sent a start signal to the gen set, it also interupted the power to the damper motor and the spring return would open the air intake damper. In this instance the damper motor was wired normally closed with power to open. My friend was with a group in the generator room when the generator was started for the first time. He described dust and paper flying around in the room and a futile effort to open the door against the partial vacuum. Eventually the engine came up to speed, the voltage stabilized, the ATS transferred and the damper motor got power and opened the air intake flaps. It generally takes less than half a minute for a good stabndby set to come on line, but I imagine that that may seem like a very long time if you are in an area of reduced pressure being pulled by the engine.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

Hi Docellen

The semisub rigs already have to meet international (and some national) damaged stability codes demanding they withstand serious flooding and loss of buoyancy. Modern semisub rigs are subdivided internally and designed to withstand loss of any 2 adjacent compartments in the columns or pontoons.

It should be noted that this was a large modern DP rig. Many older semisubs continue to operate (albeit rarely beyond 3000ft water depth) and most of them have no buoyant deckbox, just an array of girders and a plated deck. These are mainly anchored, hence no need for such a huge power plant (or direct ducted engine air intake) as found on the DP rigs like Deepwater Horizon.

As for the riser, in very deep water it requires up to 2000 tonnes of uplift at the rig to keep the riser properly tensioned. That rig uplift is what must be provided after the foam buoyancy which clads the outside of the riser itself is taken into account. It might not be impossible to add more buoyancy on the riser to improve the situation as you describe, but would be difficult.

The underwater transverse structural bracings between the pontoons of the semi would obstruct the ability to pull the rig away from the riser (even if the riser could be remotely disconnected and lowered somewhat at deck level).

I would say that somehow improving the security of the protection at the seabed end of the riser would be the best focus - although that has always been the objective with FLOATING drilling rigs - and perhaps we suffer from too much "conventional" thinking.

I think others on some other threads have made some plausible suggestions there - like "fail to closed" actuation.

RE: What would it take to avoid sinking the platform?

(OP)
JR, good discussion.  If the riser requires 2000 tonnes of tension to hold it up, how do they disconnect temporarily during a hurricane, as they are planning now with the rigs drilling the relief wells?

If we assume that the pontoons, columns, and deck box were all designed to modern standards, and had separate compartments, then perhaps the damages from the explosions were severe enough to open up large numbers of these compartments.

Maybe they should have perforated the bottom of the deck box, as soon as they saw the rig heeling over.  Maybe we need connections on each compartment of the pontoons, so we can suck out the water and provide additional buoyancy.  Just trying to think of simple, low-cost solutions.

RE: What would it take to avoid sinking the platform?

The simplest, lowest cost solution may have been to take the time to shut down long enough to repair the BOP before all this started. The rig sinking was a result or symptom, not a cause.  

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

Waross is right - the sinking was a SYMPTOM - not a cause. The real defence was to be found earlier in time and further upstream in the process. Once a fire of that intensity takes hold, it is hard to design any quantifiable/reliable defences against it.

Nevertheless, it would be interesting - although perhaps irrelevant - to know if/when the rig would have sunk if the fireboats had not fed her with water. Unburned oil flowing into the spaces would have just as bad an effect on stability as the firewater.

As for the riser when it is disconnected, it disconnects at the seabed and then hangs below the rig. It is then in TENSION due to its self weight. Tension (within limits) is a good thing for the riser as it avoids buckling in compression.

If an unsupported riser was connected to the BOP on the seabed, it would be "standing up" in compression and in danger of buckling due to it being incredibly long and slender. To change that compression to tension is why the buoyancy is added on the riser and tension is applied at the top (on the rig).

Compared to the connected riser, the only extra force the disconnected riser applies to the rig is the force which was previously acting downwards on the BOP at the seabed. And this load is limited for reasons of BOP integrity.

When the rig sank, the uplift on the riser provided by the rig and her riser tensioners disappeared, and this would have increased the downwards load on the BOP and LMRP assembly at the seabed. I don't know if this would have contributed to the post-blowout failure of the BOP to operate.

Incidentally, one area where deepwater drilling is safer/easier than shallow water drilling is in terms of riser angle. The connection of the riser to the BOP can tolerate only a limited riser angle. This angle is a function of the water depth and the horizontal offset of the rig at the surface.

The horizontal offset is caused by the wind/waves (and perhaps DP system failure). And 100m offset in 140m of water (e.g. North Sea) is far, far harder for the riser to stand than 100m offset in 2000m water depth.

This water depth thing seems to be over played in the media. On any well beyond diving depth (say 300m at a stretch) the recovery problems would have been very similar (totally dependent on ROV).

In fact, even had the well been within diving depth, it is difficult to see what saturation divers could realistically have achieved that has not already been done at Macondo.
 

RE: What would it take to avoid sinking the platform?

(OP)
The simplest, lowest cost solution is to monitor the mud flow, and detect a kick at the earliest possible moment, when it can be easily controlled.  What happened was not *caused* by bad design, but it could have been *avoided* by better design.  It bother me that engineers are not more interested in finding these better designs.  It's like having air bags fail because someone forgot to change a battery.  We can't just say "not our job".

RE: What would it take to avoid sinking the platform?

Quote:

The simplest, lowest cost solution is to monitor the mud flow, and detect a kick at the earliest possible moment, when it can be easily controlled
Monitor the mud flow. Controversial decision to replace the mud with sea water. Mud? What Mud?
Detect a kick at the earliest possible moment. I understand that the kick was detected early enough and the annular activated early enough. Annular? What annular?
As for the design of the BOP; I have wondered why the shears are not designed to be capable of shearing a joint. Other than that, this BOP had failed operations on about four or five devices. (Two annulars, two pipe blinds, and an inverted pipe blind.) It doesn't matter how good the design is if someone turns it off, (as may have happened to one of the annulars) and/or doesn't repair it in a timely manner.
I don't say that there is no need for modification, but I think that changes may be more appropriate if they are such as to facilitate easier and quicker on site repair by ROVs and make provision for ROVs to quickly and easily connect to the hydraulic systems. Another possibility may be to use edible oils in the hydraulic system so that repair operations that involve the loss of hydraulic oil are not so damaging environmentally.
 

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

Hey there's an idea.  What flavors?

Look at all the stuff on a Dreamliner.  Still won't stop somebody with poor judgment from flying it into a building.  Human brains are part of the control of these things too.  Let's be sure they function like they're supposed to before we turn them lose on the world with WM-Environmental-D.   

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying."  Tony Hayward CEO BP
"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

RE: What would it take to avoid sinking the platform?

Hi BigInch. The food processing industry uses edible oils in gear boxes in food handling areas. I'm sorry, I don't know what flavors are available.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

Waross- I'm tired of saying this, but the decision to partially displace the top of the casing and part of the riser to water ISN'T controversial- it's the only way to do an inflow pressure test on the casing....

Having done the inflow test and convinced themsleves it was ok (lets ignore the 15bbls additional bleed off, and some of the weird pressure build ups, eh?), they then continue displacing the riser to sea water as part of the suspension operations- they have a pressure tested casing (both ways!) and a BOP, so it's a perfectly normal operation.

Also , looking at the BP presentation, the kick was detected early enough at about 21:00 (almost an hour before the explosion) while they were displacing the riser (but no action taken.... why?) and then with spacer back at surface, stopping for a sheen test before diverting returns overboard.   But they continued displacing!! Why???  And then at 21:31, they stop displacing again, and I think by then they'd clearly identified something was wrong... the driller calls the Toolpusher 4 times but doesn't shut the well in!!!

One of the annulars was closed during the inflow test, (and then opened again for the displacement), but the well was never shut in despite all the indications, until 7 minutes AFTER the first explosion.

Now all of this is obvious with hindsight (and hindsignt is always 20:20.... I lost a $2million BHA once, and with hindsight it was obvious I'd nearly got stuck twice before it did get stuck), but I doubt the reported problems with one of the annulars have much bearing on the BOP failure; the issues with the hydraulic leak might explain why the susbsea acculumators didn't have the power to close the well, and certainly caused problems when they were trying to actuate the BOP with an ROV.  But we'll wait until the BOP is recovered to surface to find out what happened with the BOP, and if we have to alter all our BOPs or if this was just a cock up (like the Ekofisk blowout, where part of the BOP was upside down!)

The last thing is that as a subsea BOP control system vents to sea, I'd expect the hydraulic oils to be non damaging....

RE: What would it take to avoid sinking the platform?

Don't count on hydraulic oils being safe to drink.  Well ... I certainly wouldn't do it.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying."  Tony Hayward CEO BP
"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

RE: What would it take to avoid sinking the platform?

well BigInch, glycol isn't safe to drink (outside of Russia....) but it's on the OSPAR PLONOR list of things not damaging to the marine environment!

RE: What would it take to avoid sinking the platform?

Ug! That's why there's a zero discharge policy in US waters.  No confidence in the listed items.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying."  Tony Hayward CEO BP
"Being GREEN isn't easy." Kermitfrog http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

RE: What would it take to avoid sinking the platform?

Has this had much coverage in the US ? Next to none over here !

The journalist is taking liberties with the truth when he blames TOP OFFICIALS for wanting to sleep undisturbed as the reason for inhibiting the gas alarms. That is nowhere stated in the testimony.

I am sure alarms were inhibited so that ALL the crew could sleep.

However, this inhibition of the gas alarms (if true) may possibly have contributed to the extent of the pollution, and probably (almost certainly) had a lot to do with the loss of life.

Quite apart from sounding a general alarm, these rigs are fitted with an automatic emergency shutdown (ESD) system which should take action on detected gas. These actions include shutting down sources of ignition, closing air intakes etc - in order to minimise the dependence on human intervention to prevent explosions.

Failure of this ESD system to operate would explain some of the reports we have had of running away generators (although it seems there is something else wrong with the design/operation of that system also).

A rig with a runaway well and a disabled ESD system is a recipe for disaster. If this testimony is confirmed, then the ESD system is one intended safety barrier which was actually NOT in place.

If I recall correctly, disabled alarms/shutdowns were the major reason for Chernobyl, and perhaps Bhopal.


Alarms, detectors disabled so top rig officials could sleep
The Deepwater Horizon's fire and gas leak alarms were disabled for at least a year to prevent false alarms from waking up rig leaders, a chief engineer told federal investigators.
July 23, 2010|Rong-Gong Lin II, Los Angeles Times Staff Writer
Reporting from Kenner, La —

Critical fire and gas leak alarm systems had been disabled for at least a year aboard the Deepwater Horizon because the rig's leaders didn't want to wake up to false alarms, a rig chief engineer tech told federal investigators.

"I discovered it was 'inhibited' about a year ago," said Mike Williams, the chief engineer tech who worked for rig owner Transocean aboard the Deepwater Horizon, which erupted in flames April 20, killing 11 men and starting the worst offshore oil spill in U.S. history.

"I inquired," Williams told an investigative panel from the U.S. Coast Guard and the Interior Department in suburban New Orleans. "The explanation I got was that from the [offshore installation manager] down, they did not want people to wake up at 3 a.m. due to false alarm," Williams said. Williams later said the rig's captain had also agreed that the alarms were to be disabled.

Williams said he complained repeatedly about disabling the systems, from six months to three days prior to the rig's explosion. He said he told supervisors it was unsatisfactory for the alarms to be disabled, but was rebuffed.

The alarm systems could have been helpful to alert crew members of catastrophe and initiate an emergency shutdown system that could have shut down the engines -- a dangerous ignition source -- as soon as a surge of flammable natural gas surged up the oil well onto the rig.

Williams testified that prior to the explosions, he heard a hissing sound and heard an engine over-rev. Alarms in "inhibited" mode means that a control panel that would detect the alarm would indicate the alert, but general alarms that would sound loudly across the rig would not go off.

The emergency shutdown system also had previous problems. Williams said another employee, at some point before the April 20 disaster, inadvertently triggered an emergency shutdown system to an engine that was running. Down came fire doors intended to deprive the engine of oxygen, which would have put out a fire in the engines had there been one.

But the doors weren't built strongly. Once the doors came down, the force of the engines ripped the fire doors off their hinges.

"The engine was running. The fire dampers closed, and it sucked the fire doors off the engines," Williams said. "The function of them was to shut down the engine. If it can't get air, it can't run."

Testimony here..............................

http://edition.cnn.com/2010/US/07/23/gulf.platform.alert/index.html?section=cnn_latest#fbid=KwZ1_V5zydu
 

RE: What would it take to avoid sinking the platform?

I once had a big scare perforating offshore China when I didn't get radio silence due to the radio operator being threatened by a communist party bloke who wanted to make a phone call home- the perforating system energised while running in.

And I remember my first trip to the Montrose as Night DSV- the general alarm went at 2pm on my first day's sleep as someone had forgetted to disable them went they tested them in the control room!

Disabling any alarm is absolutely shocking, and for a OIM to agreee to it.... if true he should be NRB'd instantly.

RE: What would it take to avoid sinking the platform?

A good part of the blame should rest with the safety regulators. I have seen too many instances where a conscientious worker may lose his job and even be blackballed in that area for reporting a serious safety violation. No support or enforcement at all from the regulators.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: What would it take to avoid sinking the platform?

I 100% agree to waross;
Since indirectly this was the basic(potential)reason for my First & (could well probably be)the last Job switch over from; a Company I served Almost 28 years at a stretch of my Prime Time!

Best Regards
Qalander(Chem)

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