[QUOTE=sutluc;38436]Ahh, I understand now. I was thinking ladder logic, because that’s what I am familiar with.[/QUOTE]
[FONT=Tahoma]Yes, and those were GE PLC’s too, not Siemens, like most of the PLC’s on the rig. At least the communication protocol was Modbus for the BOP and not ProfiBus.
We can thank Alcor’s people for all this since Siemens PLC’s have taken over the market from AB and GE, their Step7 software is Statement oriented instead of Ladder and it’s all Profibus protocol if you want to talk to one. It’s that way in Drilling and Power Generation, especially big turbines since Siemens took over Allison, it looks like they have taken over NOV.
I think it’s a German/geek plot to make the code in the PLC’s less useful to the Electricians and ET’s who do the real work on the PLC’s after they are installed. They can read Ladder Logic and troubleshoot with it, but now they are stuck with calling someone (maybe me) if they think there is a problem with the logic.
Some things are so complex to program that they have to be done in Statement Logic, like Active Heave, but that can be put in blocks with Ladder around it that the boys keeping the machine running can read. But now everything I see is in statements, and there is no need for all of it, I won’t get into the German plot to push ProfiBus as a ‘universal’ communication protocol for machines but think Bill Gates and the roots of the ModBus and DeviceNet.
Am I off topic, sorry just wanted to add something insightful and there isn’t a dam thing intelligent I can add to ANY OF THE OTHER insightful threads of conversation going on here, and I’m board again. So I’ll continue lurking and be thanking you all for what you are saying and the education I’m getting about the other side of the JoyStick. Back to my electric cigarettes and watching them trip into the hole on a good old Generation III GE Rig I’ve got running now like it did 40 years ago when it was the best analog SCR system ever made, no PLC’s in sight.
OK, continue on everyone, sorry I got into my ‘bithead’ mode and geeked things up a bit, or byte, or whatever I just did.
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[QUOTE=kwCharlie;38508][FONT=Tahoma]Yes, and those were GE PLC’s too, not Siemens, like most of the PLC’s on the rig. At least the communication protocol was Modbus for the BOP and not ProfiBus.
We can thank Alcor’s people for all this since Siemens PLC’s have taken over the market from AB and GE, their Step7 software is Statement oriented instead of Ladder and it’s all Profibus protocol if you want to talk to one. It’s that way in Drilling and Power Generation, especially big turbines since Siemens took over Allison, it looks like they have taken over NOV.
I think it’s a German/geek plot to make the code in the PLC’s less useful to the Electricians and ET’s who do the real work on the PLC’s after they are installed. They can read Ladder Logic and troubleshoot with it, but now they are stuck with calling someone (maybe me) if they think there is a problem with the logic.
Some things are so complex to program that they have to be done in Statement Logic, like Active Heave, but that can be put in blocks with Ladder around it that the boys keeping the machine running can read. But now everything I see is in statements, and there is no need for all of it, I won’t get into the German plot to push ProfiBus as a ‘universal’ communication protocol for machines but think Bill Gates and the roots of the ModBus and DeviceNet.
Am I off topic, sorry just wanted to add something insightful and there isn’t a dam thing intelligent I can add to ANY OF THE OTHER insightful threads of conversation going on here, and I’m board again. So I’ll continue lurking and be thanking you all for what you are saying and the education I’m getting about the other side of the JoyStick. Back to my electric cigarettes and watching them trip into the hole on a good old Generation III GE Rig I’ve got running now like it did 40 years ago when it was the best analog SCR system ever made, no PLC’s in sight.
OK, continue on everyone, sorry I got into my ‘bithead’ mode and geeked things up a bit, or byte, or whatever I just did.
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Your providing another good insight into how things work. I can understand a bit of what you say. Don’t give up.
May I have a brief explanation of Statement Logic vs. Ladder Logic? I am assuming you are talking about computer programming - I’ve done considerable real-time programming, but not with oil rig systems.
This, I think, explains [B]a lot[/B]: http://www.nytimes.com/2010/06/28/business/global/28bptrade.html?hp What is usually a staid cash management section or sub-department in Finance is turned, altogether deliberately, into a pretty decent sized hedge fund–and a buccaneer even in [U][I]that[/I][/U] culture. [I][U]And[/U][/I] they go wwwwaaaaaaaaaayyyyyyyyyyyy over the legal edge.
You don’t have that kind of culture, responsible for 20% of net profit, neatly fenced off in its own bubble, with its own culture, its own values etc. Rather, the corner cutting, swaggering, swashbuckling was not just endemic, but admired throughout the organization. More and more, I’m coming around to hoping for liquidation, even though there is a human toll.
One other point: note that resumes are being floated. Creatures are leaving a sinking ship…
Ask what happens when the BOP reservoir pressures are below spec?
Ask the team on your platform when the last time you BOP unit was shipped back to the manufacturer for a complete rebuild?
[QUOTE=Frarig;38496]Have been trying to catch up with this thread for the last couple of days since getting to the rig. Some fairly intense discussion going on!
Anyway, I’ve been talking with the Subsea squad out here on this job (all experienced hands) and the consensus is that there is almost no chance of even a poorly-maintained BOP failing as comprehensively as the Horizon’s seems to have done. All speculation, obviously, but everyone’s money is on something more than just drill-pipe across the shears (tool joint? casing?). Failure of EDS put down to the fact that the MUX cables destroyed in initial explosion/fire. Failure of AMF (dead-man) put down to hydraulic conduit lines still intact, therefore pressure still present and therefore conditions for dead-man function not met.
So nothing that hasn’t been discussed here at length. But I’m in a good position right now to pick some brains, so if you guys/gals have questions relating to Cameron BOPs and controls, fire away and I’ll do my best to get the info.[/QUOTE]
I agree with you on the bop being a choke point, I was just being sarcastic and venting after reading some of alcors posts. It’s hard to keep the emotions down when a way of life is being screwed up because of a handful of screw-ups with stinkin-thinkin. If those corner cuttin cockroaches thought they were that lucky, they shoulda went to the casinos with the money. The picture I’m seeing is almost a designed blowout. ( only cuz I have not accepted that they could be so stupid with that many people involved and not see it, when they had the info & refused to listen to those who where trying to warn them).
[QUOTE=Docbradd;38514]May I have a brief explanation of Statement Logic vs. Ladder Logic? I am assuming you are talking about computer programming - I’ve done considerable real-time programming, but not with oil rig systems.
Thanks,[/QUOTE]
From my old ivory tower https://engineering.purdue.edu/ME576/manual/lab_9/siemensTutorialManualSm.pdf that i think you will relate to since it gets into the stack level programming. Basically: Statement Lists (or blocks) is a bunch of AND’s OR’s NOT’s and a bunch of other almost assembly level commands. Ladder is a visual display with AND as switches/contacts in series and OR as them in parallel with NC contacts NOT’ed. It’s like the difference between C (and assembly) and VB (or Java) with everything having to do with the compiler as usual; some code can’t be compiled into Ladder.
It looks like they are doing a close sub-parallel approach rather than successive sidetracks as shown in their publishes well diagram. This will be much more effective as they will drill their last stretch parallel to the original well, offset by a few feet, and then be able to perforate into it for a massive kill. Since this polished video was released on the 27th, the interviews and video segments must have been filmed on the 26th or 25th, if not earlier. The fact that they were only at 16,400 feet makes me suspect it was around midweek, but it is encouraging that by then they had already made a close pass, shot a magnetometer run, drilled closer, and then shot another one. They say they were a mere 55 feet from the wellbore, which means they could be drilling the parallel section by next weekend and could have this thing killed during the week after the July 4th holiday (I’m sure they won’t take the days off). They allowed as to how they might intercept as shallowly as 17,000 feet, rather than the originally stated 18,000 feet, which suggests we are very very close now. The biggest delay will be the setting of the final liner, which should take 3-5 days, starting sometime this week. I would guess we are within 2 weeks of a kill attempt if there are no glitches (technical problems or weather).
I’m putting my money on July 10th in the kill date pool.
[QUOTE=Frarig;38496]Have been trying to catch up with this thread for the last couple of days since getting to the rig. Some fairly intense discussion going on!
Anyway, I’ve been talking with the Subsea squad out here on this job (all experienced hands) and the consensus is that there is almost no chance of even a poorly-maintained BOP failing as comprehensively as the Horizon’s seems to have done. All speculation, obviously, but everyone’s money is on something more than just drill-pipe across the shears (tool joint? casing?). Failure of EDS put down to the fact that the MUX cables destroyed in initial explosion/fire. Failure of AMF (dead-man) put down to hydraulic conduit lines still intact, therefore pressure still present and therefore conditions for dead-man function not met.
So nothing that hasn’t been discussed here at length. But I’m in a good position right now to pick some brains, so if you guys/gals have questions relating to Cameron BOPs and controls, fire away and I’ll do my best to get the info.[/QUOTE]
What do they say about the logic sequence, in the PLC, possible being changed and could that have prevented/delayed closure, or AMF/EDS failure, yet test OK in a normal BOP test?
Another interesting find: http://www.monbiot.com/archives/2010/06/21/bps-dumb-investors/ Monbiot is an editorial columnist for the Guardian newspaper/website. He’s like, say, E. J. Dionne of the Washington Post except that he is much more ‘liberal’ than E. J., and the Guardian is Labor Party/center-left leaning, in a way that no major outlet in the U.S. is.
It’s looking like the home crowd support for [I]British[/I] Petroleum is fraying.
I have another very basic question … how is the flow of mud out of the well measured? Is it actually the flow rate on a pipe coming out of the well, or is it the volume change in the mud pit that it flows to? The difference being that if you are looking at volume change in the mud pit, then flow from the well could be offset by the unloading of mud to the work boat.
I listened to lots of questions in the MMS/USCG joint investigation that danced around the unloading of mud and whether it could have bypassed the mud pit and this and that and the other. If it doesn’t confuse the measurement of volume in/out the well then why does all that matter?
[QUOTE=Cynthia;38494]I read what I can find and leave some of it here in case it’s useful to someone that can make sense of it. One thing I’m sure of is that I don’t know enough about all this to form a judgment. You know how it goes; the more I learn, the less I know… I didn’t read that analysis to be any kind of defense of BP but rather the opposite. As for identifying any mistakes or inefficient decisions that the drill crew made… I almost hope you do find something, because I don’t want to believe that drill crews are entirely at the mercy of the suits. I want to believe that they can exercise judgment on the well and keep themselves alive. If it turns out that this isn’t the case then… I don’t know. That’s not right.[/QUOTE]
I didn’t take your reference as being in defense of BP or otherwise. I just gave my judgement of their analysis. They sounded to me to be lawyer hunting as experts. There would be as much of that as what people refer to as ambulance chasers. These guys had some good analysis to add, but got way out of their field of expertise & certainly haven’t done their research as much as the posters on this thread to be making blanket statements about other expert’s analysis that the casing design with a tieback system wouldn’t have avoided this occurance. There is no doubt to me that had BP run a proper tieback system that the odds of this disaster occuring would have decreased by 99.999%. In fact, the changes made from a tieback system to a tapered system was the number one root cause of this accident & put the rest of their casings in grave danger of a blowout outside of the casings down hole.
[QUOTE=rlanasa;38518]Ask what happens when the BOP reservoir pressures are below spec?
Ask the team on your platform when the last time you BOP unit was shipped back to the manufacturer for a complete rebuild?[/QUOTE]
For the benefit of others, I’ll answer your questions as if they were asked seriously and not as semi-sarcastic sniping.
I assume you mean the pressure in the subsea accumulator bottles? If the bottles are low and cannot be replenished from surface (for whatever reason – eg. the command signal to open accumulator isolation valves cannot be sent, damage to rigid conduit manifold etc) then you will obviously be severely limited in what pressure/flow you can exert on any function before you simply run out of fluid.
At the moment, on the rig I’m on, we have every ram removed from the BOP. All are being completely stripped, inspected by a Cameron rep, re-assembled and tested prior to installation. Both annulars are on a boat on their way to a Cameron facility for refurb. All BOP cavities are being measured. All fail-safe valves are being opened and inspected. The LMRP is in bits. Etc etc etc…
This is not as a result of the Horizon incident, it’s part of TOs normal 5-year maintenance plan.
No, it’s not quite the same as shipping the entire stack to Cameron, but have you ever actually seen one of these things, rlnasa? It’s quite big.
[QUOTE=bigmoose;38506]Frarig, thanks for the offer! If I may… A question about redundancy in blue pod/yellow pod. As I understand there were failures in the yellow pod, so they switched to blue pod. After the incident it was said that “functions were restored” after yellow pod was brought to the surface and serviced. Is the implication that there were also failures in the blue pod, or are the pods not truly redundant? Thanks again![/QUOTE]
I had asked a similar question way back in this thread and the consensus was that they reprogrammed the yellow pod to allow them to control the BOP stack like they wanted to.
[QUOTE=BLISTERS;38498]To operate the blind/shears, would there be a need to first manually energize annular accumulator pressure and then throw the bypass to the blind/shears before actuating these ? Or are these constantly pressured up automatically to be effective ? Which, if any, of the Cameroon BOPS, excluding annular elements, are assisted by seawater hydrostatic pressure for closure ? I have a very scant understanding of MUX systems, any info appreciated . Thanks![/QUOTE]
[QUOTE=BLISTERS;38498][B]To operate the blind/shears, would there be a need to first manually energize annular accumulator pressure and then throw the bypass to the blind/shears before actuating these ?[/B]
No the surface & subsea accumulators should be always charged and ready to operate even if the BOP HPU pumps are not running. (API RP 16D item 5.2.3 ) There is an alarms that goes on the BOP control panel when the accumulators are not up to required pressure. there is a gauge on the panel for BOP control of the accumulator pressure. (API RP 16 D item 5.27).
[B]Or are these constantly pressured up automatically to be effective ? [/B]
[B] Which, if any, of the Cameroon BOPS, excluding annular elements, are assisted by seawater hydrostatic pressure for closure [/B]?
On that stack of the DWH they did not use seawater assisted accumulators. (as seen in the info released by US House of Representatives) This has only been adopted by the makers recently (after 2008 ±) on BOP stacks.
The url gives the story. The Telegraph isn’t world’s most factually reliable newspaper, but this [I]looks[/I] like sound reportage.[/QUOTE]
And this: http://www.zerohedge.com/article/guest-post-bankrupt-bp-worse-financial-world-lehman-brothers may explain why Obama and Cameron said what they did. (I have my problems with zerohedge, finding them to be so bleeding edge that their reliability suffers. They are, surprisingly often, stunningly ahead of the curve; but then they are, more often than most sources, just flat wrong. Still, offered FWIW.)
[QUOTE=BLISTERS;38288]A relief well does not act as a relief valve. This is a common misconception laymen naturally assume as the name might suggest.[/QUOTE]
I don’t like the term. I wish they’d call it a Kill Well. But what do I know…