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How Can they Stop the Oil Spill?
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AlBell
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Soapy. Have you heard any internal Halliburton thinking on what went wrong?
Pulling cementing string detached BOP from mount maybe, with sea water displacement of mud?
Today it appears BP etal will try to emplace a concrete & steel capture dome over the wellhead.
Pulling cementing string detached BOP from mount maybe, with sea water displacement of mud?
Today it appears BP etal will try to emplace a concrete & steel capture dome over the wellhead.
Darth Rotor
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Does that stop, or just reduce by order(s) of magnitude, the flow out of the damaged well?
EHocking
Penultimate Amazing
All it does is sit over the leaking wellhead and capture the oil. The oil is then piped to the surface for offtake by tankers. It's merely an attempt to contain the oil leaking from the well and not something that would kill the well.
This article has a diagram at the bottom of the page that explains it pretty well.
As the article says, the device has been used before but not at this water depth.
ETA: And it goes on to say that the device may be only able to contain 85% of the oil gushing from the wellhead. So mitigation, not total containment.
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I understand after the cement job they performed a BOP test.
After that, it seems they displaced the marine riser to seawater-ironically, to avoid environmental damage. This is all mandated by the authorities.
At that point, had the well been properly cemented off, it's hard to see how there could have been pressure below the BOP.
But it seems there was. The hydrostatic head of seawater was inadequate to hold that pressure and a gas bubble migrated up the riser, expanding as it went. On reaching surface , the gas enveloped the rig and ignited- possibly after contacting engine exhausts. This is all speculation.
What baffles me is that nobody would prepare to abandon the well- which is what they were doing- until they were 100% sure it was completely cased off and cemented, with zero pressure at the wellhead.
So why was the riser displaced with gas still in the well and how did that gas get there in the first place?
I would need to see a well schematic and casing design diagram. I presume competent people have seen those and are not saying much, probably for legal reasons.
At around $520,000 a day, this was not a cheap rig to operate. I'd guess what is going through many minds is that in the push to get the Horizon Explorer off the well and onto other work, replacing it with a (presumably) cheaper rig for the final stage of the abandonment , the decision to displace the riser was taken too early, before the cement had properly cured, or before that had been adequately tested. The cement job was 20 hours earlier. After that, the string had to be tripped from bottom, the BOP tested and the riser displaced to seawater. That sounds to me like they did rather a lot in a single day.
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Darth Rotor
Salted Sith Cynic
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Thanks! Better a small leak as they drill that other well, than a large one, if that's the best that can be managed.
Thanks!
DR
Here is another version doing the rounds. Interesting.
Quoted from an email.
This well had been giving some problems all the way down and was a big discovery. Big pressure, 16ppg+ mud weight. They ran a long string of 7" production casing - not a liner, the confusion arising from the fact that all casing strings on a floating rig are run on drill pipe and hung off on the wellhead on the sea floor, like a "liner". They cemented this casing with lightweight cement containing nitrogen because they were having lost circulation in between the well kicking all the way down.
The calculations and the execution of this kind of a cement job are complex, in order that you neither let the well flow from too little hydrostatic pressure nor break it down and lose the fluid and cement from too much hydrostatic. But you gotta believe BP had 8 or 10 of their best double and triple checking everything.
On the outside of the top joint of casing is a seal assembly - "packoff" - that sets inside the subsea wellhead and seals. This was set and tested to 10,000 psi, OK. Remember they are doing all this from the surface 5,000 feet away. The technology is fascinating, like going to the moon or fishing out the Russian sub, or killing all the fires in Kuwait in 14 months instead of 5 years. We never have had an accident like this before so hubris, the folie d'grandeur, sort of takes over. BP were the leaders in all this stretching the envelope all over the world in deep water.
This was the end of the well until testing was to begin at a later time, so a temporary "bridge plug" was run in on drill pipe to set somewhere near the top of the well below 5,000 ft. This is the second barrier, you always have to have 2, and the casing was the first one. It is not know if this was actually set or not. At the same time they took the 16+ ppg mud out of the riser and replaced it with sea water so that they could pull the riser, lay it down, and move off.
When they did this, they of course took away all the hydrostatic on the well. But this was OK, normal, since the well was plugged both on the inside with the casing and on the outside with the tested packoff. But something turned loose all of a sudden, and the conventional wisdom would be the packoff on the outside of the casing.
Gas and oil rushed up the riser; there was little wind, and a gas cloud got all over the rig. When the main inductions of the engines got a whiff, they ran away and exploded. Blew them right off the rig. This set everything on fire. A similar explosion in the mud pit / mud pump room blew the mud pumps overboard. Another in the mud sack storage room, sited most unfortunately right next to the living quarters, took out all the interior walls where everyone was hanging out having - I am not making this up - a party to celebrate 7 years of accident free work on this rig. 7 BP bigwigs were there visiting from town.
In this sense they were lucky that the only ones lost were the 9 rig crew on the rig floor and 2 mud engineers down on the pits. The furniture and walls trapped some and broke some bones but they all managed to get in the lifeboats with assistance from the others.
The safety shut ins on the BOP were tripped but it is not clear why they did not work. This system has 4 way redundancy; 2 separate hydraulic systems and 2 separate electric systems should be able to operate any of the functions on the stack. They are tested every 14 days, all of them. (there is also a stab on the stack so that an ROV can plug in and operate it, but now it is too late because things are damaged).
The well is flowing through the BOP stack, probably around the outside of the 7" casing. As reported elsewhere, none of the "rams", those being the valves that are suppose to close around the drill pipe and / or shear it right in two and seal on the open hole, are sealing. Up the riser and out some holes in it where it is kinked. A little is coming out of the drill pipe too which is sticking out of the top of the riser and laid out on the ocean floor. The volumes as reported by the media are not correct but who knows exactly how much is coming?
2 relief wells will be drilled but it will take at least 60 days to kill it that way. There is a "deep sea intervention vessel" on the way, I don't know if that means a submarine or not, one would think this is too deep for subs, and it will have special cutting tools to try to cut off the very bottom of the riser on top of the BOP. The area is remarkably free from debris. The rig "Enterprise" is standing by with another BOP stack and a special connector to set down on top of the original one and then close. You saw this sort of thing in Red Adair movies and in Kuwait, a new stack dangling from a crane is just dropped down on the well after all the junk is removed. But that is not 5,000 ft underwater.
One unknown is if they get a new stack on it and close it, will the bitch broach around the outside of all the casing??
In order for a disaster of this magnitude to happen, more than one thing has to go wrong, or fail. First, a ****** cement job. The wellhead packoff / seal assembly, while designed to hold the pressure, is just a backup. And finally, the ability to close the well in with the BOP somehow went away.
A bad deal for the industry, for sure. Forget about California and Florida. Normal operations in the Gulf will be overregulated like the N. Sea. And so on.
Pretty much echoes what I said above. I guessed the two MI Swaco guys had to be the mud engineers- who were probably offloading mud to a supply boat at the time the gas hit surface. My job. I'm wth Halliburton, not MI, but the colour of the coveralls don't count for much.
ETA- Just a note- although BP seems to be taking the rap for this, it should be pointed out they are not sole operator. MOEX and Anadarko are partners in the well.
Quoted from an email.
This well had been giving some problems all the way down and was a big discovery. Big pressure, 16ppg+ mud weight. They ran a long string of 7" production casing - not a liner, the confusion arising from the fact that all casing strings on a floating rig are run on drill pipe and hung off on the wellhead on the sea floor, like a "liner". They cemented this casing with lightweight cement containing nitrogen because they were having lost circulation in between the well kicking all the way down.
The calculations and the execution of this kind of a cement job are complex, in order that you neither let the well flow from too little hydrostatic pressure nor break it down and lose the fluid and cement from too much hydrostatic. But you gotta believe BP had 8 or 10 of their best double and triple checking everything.
On the outside of the top joint of casing is a seal assembly - "packoff" - that sets inside the subsea wellhead and seals. This was set and tested to 10,000 psi, OK. Remember they are doing all this from the surface 5,000 feet away. The technology is fascinating, like going to the moon or fishing out the Russian sub, or killing all the fires in Kuwait in 14 months instead of 5 years. We never have had an accident like this before so hubris, the folie d'grandeur, sort of takes over. BP were the leaders in all this stretching the envelope all over the world in deep water.
This was the end of the well until testing was to begin at a later time, so a temporary "bridge plug" was run in on drill pipe to set somewhere near the top of the well below 5,000 ft. This is the second barrier, you always have to have 2, and the casing was the first one. It is not know if this was actually set or not. At the same time they took the 16+ ppg mud out of the riser and replaced it with sea water so that they could pull the riser, lay it down, and move off.
When they did this, they of course took away all the hydrostatic on the well. But this was OK, normal, since the well was plugged both on the inside with the casing and on the outside with the tested packoff. But something turned loose all of a sudden, and the conventional wisdom would be the packoff on the outside of the casing.
Gas and oil rushed up the riser; there was little wind, and a gas cloud got all over the rig. When the main inductions of the engines got a whiff, they ran away and exploded. Blew them right off the rig. This set everything on fire. A similar explosion in the mud pit / mud pump room blew the mud pumps overboard. Another in the mud sack storage room, sited most unfortunately right next to the living quarters, took out all the interior walls where everyone was hanging out having - I am not making this up - a party to celebrate 7 years of accident free work on this rig. 7 BP bigwigs were there visiting from town.
In this sense they were lucky that the only ones lost were the 9 rig crew on the rig floor and 2 mud engineers down on the pits. The furniture and walls trapped some and broke some bones but they all managed to get in the lifeboats with assistance from the others.
The safety shut ins on the BOP were tripped but it is not clear why they did not work. This system has 4 way redundancy; 2 separate hydraulic systems and 2 separate electric systems should be able to operate any of the functions on the stack. They are tested every 14 days, all of them. (there is also a stab on the stack so that an ROV can plug in and operate it, but now it is too late because things are damaged).
The well is flowing through the BOP stack, probably around the outside of the 7" casing. As reported elsewhere, none of the "rams", those being the valves that are suppose to close around the drill pipe and / or shear it right in two and seal on the open hole, are sealing. Up the riser and out some holes in it where it is kinked. A little is coming out of the drill pipe too which is sticking out of the top of the riser and laid out on the ocean floor. The volumes as reported by the media are not correct but who knows exactly how much is coming?
2 relief wells will be drilled but it will take at least 60 days to kill it that way. There is a "deep sea intervention vessel" on the way, I don't know if that means a submarine or not, one would think this is too deep for subs, and it will have special cutting tools to try to cut off the very bottom of the riser on top of the BOP. The area is remarkably free from debris. The rig "Enterprise" is standing by with another BOP stack and a special connector to set down on top of the original one and then close. You saw this sort of thing in Red Adair movies and in Kuwait, a new stack dangling from a crane is just dropped down on the well after all the junk is removed. But that is not 5,000 ft underwater.
One unknown is if they get a new stack on it and close it, will the bitch broach around the outside of all the casing??
In order for a disaster of this magnitude to happen, more than one thing has to go wrong, or fail. First, a ****** cement job. The wellhead packoff / seal assembly, while designed to hold the pressure, is just a backup. And finally, the ability to close the well in with the BOP somehow went away.
A bad deal for the industry, for sure. Forget about California and Florida. Normal operations in the Gulf will be overregulated like the N. Sea. And so on.
Pretty much echoes what I said above. I guessed the two MI Swaco guys had to be the mud engineers- who were probably offloading mud to a supply boat at the time the gas hit surface. My job. I'm wth Halliburton, not MI, but the colour of the coveralls don't count for much.
ETA- Just a note- although BP seems to be taking the rap for this, it should be pointed out they are not sole operator. MOEX and Anadarko are partners in the well.
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Nosi
Illuminator
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I heard some hearsay (sorry no links) from a neighbor that this gusher could destroy the entire ecosystem of the Earth's oceans. His trousers were about to do their own gushing, but that was another story. Then, when we loose the oceans, we will loose Earth's oxy supply.
post 88 is cut from a private email. I suspect it's based on a radio interview with a survivor who was on the rig at the time.
The email is circulating widely in the drilling community.
Earlier comments from me are derived from coverage of the story at http://www.rigzone.com, an industry website. I have already linked to it.
If your point is that speculation based on minimal data is of questionable value, I agree. However, the information is all available. The only reason we need to speculate is because that information is not being disseminated.
The only reason I can imagine for that is that the matter is sub judice, which, given the existence of functionally similar rigs, operating world wide in conditions as dangerous as this well, strikes me as profoundly stupid and criminally negligent. We (by which I mean people like me who live and work half our lives on such structures) need to know what went wrong. I don't give a damn what lawyers need.
ETA- And if anyone thinks keeping wraps on the data will stop speculation, they need their head examined.
Here's another email- I have removed names.
[FONT=Comic Sans MS, sans-serif][FONT=Comic Sans MS, sans-serif]
>
> TALKED TO MY SON, HE IS AT HOME NOW, AND IN GOOD SHAPE, WHAT I WAS TOLD WAS
> THEY HAD SET A 9-5/8 TAPERED PRODUCTION LINER, DID THEIR CEMENT JOB, HAD
> POSITIVE TESTED, AND ALSO NEGATIVE TESTED, THEY WERE GOING TO SET A BALANCED
> PLUG AROUND 3000' BELOW THE WELL HEAD WHICH WOULD BE AT ABOUT 8000', THE
> SENIOR COMPANY MAN WANTED TO SET THE BALANCED PLUG IN MUD, BUT THE ENGINEERS
> WANTED TO DISPLACE WITH WATER PRIOR TO SETTING BALANCED PLUG, SO THEY
> DISPLACED FROM 3000' BELOW MUD LINE, AND WERE GETTING READY TO SET PLUG. THE
> DERRICKMAN CALLED THE DRILLER AND SAID HE NEEDED HELP, HE HAD MUD GOING
> EVERYWHERE, AND ABOUT THIS TIME THE DRILL FLOOR DISAPEARED, THEN THERE WAS
> AN EXPLOSION, THEN A SECOND EXPLOSION.
>
> THE FLAMES ARE NOW GOING STRAIGHT UP ALLOWING EVACUATION OF MEN, THEN YOU
> KNOW THE REST.
>
> THE HANDS THAT ARE MISSING ARE THE ONES THAT WERE ON THE DRILL FLOOR AND
> PUMP ROOM. YOU KNOW THE RESULTS OF THAT. THIS ALL TOOK PLACE IN LESS THAN A
> MINUTE.
>
> RIG WAS EVACUATED IN ABOUT 25 MINUTES.
>
> IT IS BELIVED THAT THE SEAL ASSEMBLY AT THE WELL HEAD GAVE UP. IF THAT IS
> THE CASE AND THEY WOULD HAVE SET THE BALANCED PLUG IN MUD THEN DISPLACED THE
> RISER, IT WOULD ONLY HAVE DELAYED WHAT HAPPENED BY A COUPLE OF HOURS.
>
> GAS MUST HAVE CHANNELLED THROUGH THE CEMENT JOB AND UP THE BACK SIDE OF THE
> 9-5/8 PRODUCTION CASING.
Note:- in oilfield parlance normally a "casing" is a steel cylinder that is run from surface to the bottom of the well and cemented in place. A "Liner" is a similar cylinder that does not run all the way to surface. In deepwater offshore worl, all casins terminate at the wellhead on the seabed, so the terminology gets confusing.
Increasingly, I'm getting the impression something went very wrong with the casing cement job, but that only became apparent when the riser was displaced to seawater. However, that should have been apparent almost immediately- and before the gas kick reached surface. Had the BOP been closed immediately a mud pit gain began, the rig might have been saved.
But- it seems at the time the gas kick was entering the well, the mud engineers were offloading mud to a supply boat- so any gain in the mud pits may have been offset by a drop caused by that transfer. The mud loggers might then have been confused by which pits contained mud and which water. This is speculation on my part- but based on a common situation I have seen during similar operations.
[/FONT][/FONT]
The email is circulating widely in the drilling community.
Earlier comments from me are derived from coverage of the story at http://www.rigzone.com, an industry website. I have already linked to it.
If your point is that speculation based on minimal data is of questionable value, I agree. However, the information is all available. The only reason we need to speculate is because that information is not being disseminated.
The only reason I can imagine for that is that the matter is sub judice, which, given the existence of functionally similar rigs, operating world wide in conditions as dangerous as this well, strikes me as profoundly stupid and criminally negligent. We (by which I mean people like me who live and work half our lives on such structures) need to know what went wrong. I don't give a damn what lawyers need.
ETA- And if anyone thinks keeping wraps on the data will stop speculation, they need their head examined.
Here's another email- I have removed names.
[FONT=Comic Sans MS, sans-serif][FONT=Comic Sans MS, sans-serif]
>
> TALKED TO MY SON, HE IS AT HOME NOW, AND IN GOOD SHAPE, WHAT I WAS TOLD WAS
> THEY HAD SET A 9-5/8 TAPERED PRODUCTION LINER, DID THEIR CEMENT JOB, HAD
> POSITIVE TESTED, AND ALSO NEGATIVE TESTED, THEY WERE GOING TO SET A BALANCED
> PLUG AROUND 3000' BELOW THE WELL HEAD WHICH WOULD BE AT ABOUT 8000', THE
> SENIOR COMPANY MAN WANTED TO SET THE BALANCED PLUG IN MUD, BUT THE ENGINEERS
> WANTED TO DISPLACE WITH WATER PRIOR TO SETTING BALANCED PLUG, SO THEY
> DISPLACED FROM 3000' BELOW MUD LINE, AND WERE GETTING READY TO SET PLUG. THE
> DERRICKMAN CALLED THE DRILLER AND SAID HE NEEDED HELP, HE HAD MUD GOING
> EVERYWHERE, AND ABOUT THIS TIME THE DRILL FLOOR DISAPEARED, THEN THERE WAS
> AN EXPLOSION, THEN A SECOND EXPLOSION.
>
> THE FLAMES ARE NOW GOING STRAIGHT UP ALLOWING EVACUATION OF MEN, THEN YOU
> KNOW THE REST.
>
> THE HANDS THAT ARE MISSING ARE THE ONES THAT WERE ON THE DRILL FLOOR AND
> PUMP ROOM. YOU KNOW THE RESULTS OF THAT. THIS ALL TOOK PLACE IN LESS THAN A
> MINUTE.
>
> RIG WAS EVACUATED IN ABOUT 25 MINUTES.
>
> IT IS BELIVED THAT THE SEAL ASSEMBLY AT THE WELL HEAD GAVE UP. IF THAT IS
> THE CASE AND THEY WOULD HAVE SET THE BALANCED PLUG IN MUD THEN DISPLACED THE
> RISER, IT WOULD ONLY HAVE DELAYED WHAT HAPPENED BY A COUPLE OF HOURS.
>
> GAS MUST HAVE CHANNELLED THROUGH THE CEMENT JOB AND UP THE BACK SIDE OF THE
> 9-5/8 PRODUCTION CASING.
Note:- in oilfield parlance normally a "casing" is a steel cylinder that is run from surface to the bottom of the well and cemented in place. A "Liner" is a similar cylinder that does not run all the way to surface. In deepwater offshore worl, all casins terminate at the wellhead on the seabed, so the terminology gets confusing.
Increasingly, I'm getting the impression something went very wrong with the casing cement job, but that only became apparent when the riser was displaced to seawater. However, that should have been apparent almost immediately- and before the gas kick reached surface. Had the BOP been closed immediately a mud pit gain began, the rig might have been saved.
But- it seems at the time the gas kick was entering the well, the mud engineers were offloading mud to a supply boat- so any gain in the mud pits may have been offset by a drop caused by that transfer. The mud loggers might then have been confused by which pits contained mud and which water. This is speculation on my part- but based on a common situation I have seen during similar operations.
[/FONT][/FONT]
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TraneWreck
Philosopher
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Yeah, thanks Soapy, that's interesting stuff.
EHocking
Penultimate Amazing
IMO At 65% and also the permit operator, BP would have been, for all intents an purposes, "in charge" of operations. MOEX and Anadarko would probably have been consulted on drilling programme changes and advised on what sort abandonment was to be considered, but the operations and engineering of the abandonment would have been done under BP's direct supervison.
Whether sole operator or not - BP was the operator which did the well design, hired the rig and supervised the operations. Most of the blame will be on their heads. The only "get out" for them would be if Transocean did not follow BP's procedures, or if other 3rd parties (such as the cementers) didn't.
But even not know all the circumstances of the disaster, BP was in charge, so legally, are going to be the most responsible.
AlBell
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More problems; methane hydrate blocking the outlet of the catchment dome.
http://green.blogs.nytimes.com/2010/05/08/problem-for-containment-dome-in-gulf/?hp
http://green.blogs.nytimes.com/2010/05/08/problem-for-containment-dome-in-gulf/?hp
Or if the procedures were followed as per U.S. regulation, but were inadequate. This is a new (and , by the looks of it, interesting), field. If procedures were followed, they clearly need revised, before further drilling goes ahead.
I've heard no complaint about legal, moral or environmental responsibility from BP, but given the (to my mind) unfortunate stress by some Stateside commentators on this being a British operation, I think it's worth keeping in mind that this well was drilled to American rules, by an American rig, crewed by American companies. The issue is not who dunnit, but what , exactly, did someone do wrong? This we need to know, Americans, Brits and everyone else.
AlBell
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I noted a comment (don't recall where) that the blind rams may not have been capable of cutting the newest high-tensile pipe being used on this well.
Anyone know when, if ever, blind rams actually get tested once the BOP leaves the factory? It is SOP by current US regs to test BOP bi-weekly, but I suspect that is just on the pipe rams.
Anyone know when, if ever, blind rams actually get tested once the BOP leaves the factory? It is SOP by current US regs to test BOP bi-weekly, but I suspect that is just on the pipe rams.
rwguinn
Penultimate Amazing
Soapy-
Are you saying that the probable situation is that the plug holding the casing in place is what blew out?
Since the casing is suspended (If I read your comments correctly) then the casing string would have blown at least partially out of the hole and possibly broken off, fouling the whole shebang.
If all this is the case, then the "acoustic shut-off", or whatever would have been another redundancy that wouldn't have done a damn bit of good, either.
(It's been years since I dealt with this stuff, so forgive me if I misconstrued it)
Are you saying that the probable situation is that the plug holding the casing in place is what blew out?
Since the casing is suspended (If I read your comments correctly) then the casing string would have blown at least partially out of the hole and possibly broken off, fouling the whole shebang.
If all this is the case, then the "acoustic shut-off", or whatever would have been another redundancy that wouldn't have done a damn bit of good, either.
(It's been years since I dealt with this stuff, so forgive me if I misconstrued it)
1. I'm not privy to any data not already posted in this thread, so
2. I'm expressing an opinion, no more,based on hearsay data, when I say this-
The BOP tested OK. Had the guide base or casing hanger assembly been compromised, that would- almost certainly- not be the case.
I don't know why the riser was displaced to seawater when it was, before the final cement plug was in place. It's absolutely the last thing I'd have done and had I been there I'd have quit before agreeing to it, based on what I've read. The man in my place agreed and I must suppose he had good reason for that. He knew more than I do, or had reason to believe he did.
I can't believe he would have agreed unless he thought the cement job was solid. But given the time frame- 20 hours earlier-with a BOP test and a trip afterward- I don't see how he could have known that. I don't think there was time. But the timing I've seen may be wrong.
I'm at a loss. A catastrophic failure of the BOP seems just too unlikely.
We know the gas entered the well. That means the reservoir was not cemented off. It still isn't, hence the ongoing oil (and presumably gas) release.
I think the cement job failed to isolate the reservoir and the displacement of the riser to seawater doomed eleven men by allowing the well to kick. I also wonder where that decision was taken- on the rig or in town?
I suspect the kick was not caught early enough to stop (by closing the annular preventer) because simultaneous operations confused the loggers monitoring the well- but that's a guess based on the fact I've seen just that happen often. I think someone got in a hurry.
2. I'm expressing an opinion, no more,based on hearsay data, when I say this-
The BOP tested OK. Had the guide base or casing hanger assembly been compromised, that would- almost certainly- not be the case.
I don't know why the riser was displaced to seawater when it was, before the final cement plug was in place. It's absolutely the last thing I'd have done and had I been there I'd have quit before agreeing to it, based on what I've read. The man in my place agreed and I must suppose he had good reason for that. He knew more than I do, or had reason to believe he did.
I can't believe he would have agreed unless he thought the cement job was solid. But given the time frame- 20 hours earlier-with a BOP test and a trip afterward- I don't see how he could have known that. I don't think there was time. But the timing I've seen may be wrong.
I'm at a loss. A catastrophic failure of the BOP seems just too unlikely.
We know the gas entered the well. That means the reservoir was not cemented off. It still isn't, hence the ongoing oil (and presumably gas) release.
I think the cement job failed to isolate the reservoir and the displacement of the riser to seawater doomed eleven men by allowing the well to kick. I also wonder where that decision was taken- on the rig or in town?
I suspect the kick was not caught early enough to stop (by closing the annular preventer) because simultaneous operations confused the loggers monitoring the well- but that's a guess based on the fact I've seen just that happen often. I think someone got in a hurry.
AlBell
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The bad cement job seems certain. I'm not sure that the annular preventer would have solved the problem with pipe still in the hole; some oil was observed coming from the pipe although BP did get this shut off a couple days ago by installing a valve on the end. The main spill is apparently still from the bent & broken riser.
It still looks to me like the BOP stack had yet unknown problems; it is 'broken' in that the ROV stab couldn't actuate it, although whether that method ever envisioned shearing pipe with the blind rams isn't something I know.
I did look at the MMS BOP test guidelines, and blind rams are tested at least every 30 days, although it appears the test just pressures up and holds for a few minutes.
It still looks to me like the BOP stack had yet unknown problems; it is 'broken' in that the ROV stab couldn't actuate it, although whether that method ever envisioned shearing pipe with the blind rams isn't something I know.
I did look at the MMS BOP test guidelines, and blind rams are tested at least every 30 days, although it appears the test just pressures up and holds for a few minutes.