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Started By
Message
Possible WTF ?
Posted on 5/13/10 at 3:26 pm
Posted on 5/13/10 at 3:26 pm
Someone in the know, please look at the pdf file at this LINK- page 3 specifically.
The entry DO NOT FUNCTION AS PER EXEMPTION for the status of the Blind Shear Rams and Casing Shear Rams caught my attention.
Are these the BOP functions that everybody was hoping would shut this thing off?
What exemption are they talking about, not having to test them or not having to install them in the first place?
The entry DO NOT FUNCTION AS PER EXEMPTION for the status of the Blind Shear Rams and Casing Shear Rams caught my attention.
Are these the BOP functions that everybody was hoping would shut this thing off?
What exemption are they talking about, not having to test them or not having to install them in the first place?
5
Posted on 5/13/10 at 3:43 pm to reverendotis
ummm, OUCH!! man this is waaay over my head. How did you get a record of this report? Is it public information now?
Posted on 5/13/10 at 3:49 pm to reverendotis
well, i can only venture a few guesses, since i don't know whether this was a standard BOP test or the initial test upon latching up to the well (date listed as 2/10/2010 at the top of the chart):
The specific rams in question are Cameron's Super Shear Casing Rams. These things are badass and can cut damn near anything you put across them; however, all they do is cut, they do not hold pressure.
These rams are not the most tolerant in dealing w/ debris, and there is a way for debris to collect over time on the top and bottoms of the ram blocks. If this occurs, and the rams are functioned, there is a good chance that the debris will fall behind the block as it extends out into the bore to cut. This does not effect the ram's effectiveness in making the cut.
The problem comes up when you try and retract the rams at the conclusion of the cut. The hydraulic operators will try to pull the rams back, but debris will block the path. Something's got to give, and the hydraulic operator will fail, leaving the ram partially hung out in the bore of the BOP after executing the shear sequence.
This is a well understood phenomenon with this particular piece of equipment, and it is an accepted practise not to function these things unless absolutely necessary, for fear of never being able to retract them. they are typically functioned at surface (after confirming all debris has been removed from the ram cavity), but not functioned subsea. the other fear is that the hydraulic operator could fail during a routine function, and when you really needed them in an emergency, they wouldn't execute the function properly due to the broken operator.
the "exemption" referenced on the sheet is a waiver from the MMS not to perform a function test of the super shears on the regular shear ram cycle. this waiver would be applied for (and approved) in the original permit to drill.
The specific rams in question are Cameron's Super Shear Casing Rams. These things are badass and can cut damn near anything you put across them; however, all they do is cut, they do not hold pressure.
These rams are not the most tolerant in dealing w/ debris, and there is a way for debris to collect over time on the top and bottoms of the ram blocks. If this occurs, and the rams are functioned, there is a good chance that the debris will fall behind the block as it extends out into the bore to cut. This does not effect the ram's effectiveness in making the cut.
The problem comes up when you try and retract the rams at the conclusion of the cut. The hydraulic operators will try to pull the rams back, but debris will block the path. Something's got to give, and the hydraulic operator will fail, leaving the ram partially hung out in the bore of the BOP after executing the shear sequence.
This is a well understood phenomenon with this particular piece of equipment, and it is an accepted practise not to function these things unless absolutely necessary, for fear of never being able to retract them. they are typically functioned at surface (after confirming all debris has been removed from the ram cavity), but not functioned subsea. the other fear is that the hydraulic operator could fail during a routine function, and when you really needed them in an emergency, they wouldn't execute the function properly due to the broken operator.
the "exemption" referenced on the sheet is a waiver from the MMS not to perform a function test of the super shears on the regular shear ram cycle. this waiver would be applied for (and approved) in the original permit to drill.
Posted on 5/13/10 at 3:50 pm to reverendotis
I may be ignorant but wouldn't testing the shear rams actually cut the casing so I don't see why an exemption on this test once the unit is installed would be an issue.
Posted on 5/13/10 at 3:54 pm to bayoudude
no. the function test involves simply closing the ram, recording the gallons of fluid required to execute the function, then commanding the component to open.
Actual shear testing is done by the shear ram vendor at their shop, and is typically done at the behest of someone like BP, Chevron, Shell, etc to see if the ram will cut a specific item which both the drilling contractor and operator have limited experience with.
Actual shear testing is done by the shear ram vendor at their shop, and is typically done at the behest of someone like BP, Chevron, Shell, etc to see if the ram will cut a specific item which both the drilling contractor and operator have limited experience with.
Posted on 5/13/10 at 3:56 pm to oilfieldtiger
So there must be stops on the ram that are actuated for the test then. I can't see how you could test the pressure on the ram without stroking the shears and cutting the casing.
Posted on 5/13/10 at 4:01 pm to bayoudude
i was referring strictly to a function test. the pressure test is different.
these particular casing shear rams cannot be pressure tested, since they don't hold any pressure.
the blind shear rams are tested every 30 days and functioned every 14. So ever thirty days, you have to close them and perform the test from below to the required pressure. you do not cut pipe during this test.
for the function test, you just function them closed, and the BOP panel will indicate whether the command was executed successfully and the gallons of hydraulic fluid required to close, then open them.
the remaining components of the bop stack are function tested every 7 days and pressure tested every 14.
to be clear, each individual ram has its open set of hydraulic operators that are commanded independently.
these particular casing shear rams cannot be pressure tested, since they don't hold any pressure.
the blind shear rams are tested every 30 days and functioned every 14. So ever thirty days, you have to close them and perform the test from below to the required pressure. you do not cut pipe during this test.
for the function test, you just function them closed, and the BOP panel will indicate whether the command was executed successfully and the gallons of hydraulic fluid required to close, then open them.
the remaining components of the bop stack are function tested every 7 days and pressure tested every 14.
to be clear, each individual ram has its open set of hydraulic operators that are commanded independently.
This post was edited on 5/13/10 at 4:02 pm
Posted on 5/13/10 at 4:11 pm to oilfieldtiger
what size was the BOP stack? 10M?
Posted on 5/13/10 at 4:13 pm to AcadianDisciple
15k rams, 10k annular
Posted on 5/13/10 at 4:19 pm to oilfieldtiger
13-5/8"?
Posted on 5/13/10 at 4:21 pm to AcadianDisciple
18 3/4"
Posted on 5/13/10 at 4:31 pm to oilfieldtiger
I'm hearing a company other than cameron may have worked on these BOPs. May not be fact, who knows.
Posted on 5/13/10 at 4:50 pm to reverendotis
Exemptions like this are not uncommon with MMS. It could have to do with which phase they are in. There's a lot that goes into it that the sheet doesn't shot. For instance, if we wanted to test a BOP a day later than normal, that's an exemption. Also, if we wanted to test a day earlier, that's classified as an exemption also.
That report is not public information, and posting it, or sharing that with anyone via a public forum, or via email, could potentially open up a can of legal worms for anyone caught sharing it.
I'd edit the OP and remove it.
quote:
reverendotis
That report is not public information, and posting it, or sharing that with anyone via a public forum, or via email, could potentially open up a can of legal worms for anyone caught sharing it.
I'd edit the OP and remove it.
Posted on 5/13/10 at 5:09 pm to BROffshoreTigerFan
quote:
That report is not public information, and posting it, or sharing that with anyone via a public forum, or via email, could potentially open up a can of legal worms for anyone caught sharing it.
ETA II: to take out the BS....A little harsh. Sorry.
ETA: did you notice where the link takes you?
This post was edited on 5/13/10 at 5:30 pm
Posted on 5/13/10 at 5:18 pm to Sid in Lakeshore
quote:
bullshite.
ETA: did you notice where the link takes you?
Generally, it is not public information. Yes, I did see where it was from. Considering that it's from that website (I didn't notice it initially) and anything that came up in the investigation, is going to be available.
But I stand by my initial post. BOP test charts are not public information. At least according to the company I work for, their engineers and superintendents.
Posted on 5/13/10 at 5:41 pm to BROffshoreTigerFan
quote:
Generally, it is not public information. Yes, I did see where it was from. Considering that it's from that website (I didn't notice it initially) and anything that came up in the investigation, is going to be available.
Thought about that before posting but this (plus other documents including hard copies of some well logs) are part of the ongoing hearings in DC and as such are public record.
Back to my original line of questioning - are these the only shearing rams on the BOP stack?
Aren't these the ones that everybody was hoping to be able to close to shut this thing off in the first few days after they realized they had a leaking well?
Is it standard operating procedure for MMS to grant permission to not test the mechanism ultimately capable of preventing this type of disaster? Can't be?
Posted on 5/13/10 at 7:13 pm to reverendotis
quote:
Back to my original line of questioning - are these the only shearing rams on the BOP stack?
Aren't these the ones that everybody was hoping to be able to close to shut this thing off in the first few days after they realized they had a leaking well?
Is it standard operating procedure for MMS to grant permission to not test the mechanism ultimately capable of preventing this type of disaster? Can't be?
the casing shear rams work in conjunction w/ a set of blind shear rams -- the casing shears cut and the blind shears hold pressure. the blind shear rams are the rams that have both a shearing capability AND hold pressure from below -- the casing sheaer rams only cut.
as i stated above, no waiver was issued for the blind shear rams, and they are functioned every 14 days and pressure tested every 30. the waiver issued is only specifically related to the cameron super shears -- not the blind shears, not the annular, and not any of the pipe rams.
the most likely ram they were trying to function close w/ the ROV was the blind shears, but i'm sure they tried to function everything on that stack in an effort to reduce/stop the flow.
so when an emergency disconnect / auto shear is initiated, the casing shear rams cut first. this severs whatever is across the stack, w/ the lower section falling down the hole and the upper section rebounding upward due to the loss of weight beneath it. ~20 seconds later, the blind shear rams close, ideally w/ nothing across them and the well is secured. however, if there is something across them, they have the functionality to cut it as well and still hold pressure. the blind shears just can't cut the full range of tubulars that the casing shear rams can. for instance, the blind shears can't cut 16" casing, but the casing shears can.
this is all unique to this particular 15k cameron BOP stack. other vendors' stacks have different shearing capabilities.
This post was edited on 5/13/10 at 7:24 pm
Posted on 5/13/10 at 7:36 pm to oilfieldtiger
quote:
oilfieldtiger
Nice description.
Posted on 5/14/10 at 5:30 am to reverendotis
quote:
Thought about that before posting but this (plus other documents including hard copies of some well logs) are part of the ongoing hearings in DC and as such are public record.
Because I work with these so closely, when I first saw it, my initial reaction was "frick that's not good".
I hadn't thought about the investigation and that all the facts, morning reports, BOP test charts, etc. were going to be made public. TBO, I was too interested in reading the charts to actually see where it was coming from. quote:
ETA II: to take out the BS....A little harsh. Sorry.
Sid, you should have left up the initial post. It was my stupidity for not looking at the link. I'd rather someone point out a mistake then leave it be so I post inaccurate information. Unless we're on the OT. Not much there is true anyway.
Posted on 5/14/10 at 5:37 am to bayoudude
quote:
I may be ignorant but wouldn't testing the shear rams actually cut the casing so I don't see why an exemption on this test once the unit is installed would be an issue.
This.
At least, that was my read on it. Dunno if it is valid or not.
EDIT: Thank you oilfieldtiger
This post was edited on 5/14/10 at 5:41 am
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