Deepwater Oil Spill - Permissions and Concerns about Top Kill
Posted by Heading Out on May 26, 2010 - 10:18pm
Rather than stick continuous updates on the previous post, I am going to add them as updates to this separate post on the progress of the Deepwater Top Kill attempt.
By 1 pm Louisiana time, permission had been obtained from Admiral Landry to go ahead with the top kill procedure. The team is therefore waiting for final approval from the top folks at BP, before going ahead.
There have to be concerns about the increasing number of leaks at the riser near the blowout preventer (BOP), which is lowering the flow out of the end of the riser (and which were visible on a CNN feed earlier this morning). Leaks of a fluid that is carrying abrasive particles can get larger very quickly, and can threaten the integrity of the BOP. This now, therefore, becomes a driver to accelerate the process, given that if the flow is allowed to continue, the BOP may be further eroded and weakened and may collapse. And even if it were not to collapse, there is concern that the resistance to the pressure of the top kill process will decline as it erodes.
We are at a point where endless discussion and the need for permit after permit begins to have a negative impact on success.
Note: Live discussion has moved to http://www.theoildrum.com/node/6516
UPDATE - Well, so much for impatience, the process has been started, and we should know fairly quickly whether it works.
UPDATE 2: There appears to be mud coming from the leaks at the top of the BOP, showing they have started pumping at 2 pm
UPDATE 3: Well, BP said that they would provide a live feed, they just didn't say which one - grin - so the feeds are now showing things such as parts of the BOP, where they were looking for leaks initially, but where nothing much is now happening, But it does seem from the occasional glance of the leak near the top of the BOP that they are increasing the pressure on the feed to the well at 2:30 pm. Hmm, now CNN are showing the top leak, and if you look at the one at the back, it noticeably got bigger in the last couple of minutes.
(Oh, and for those watching CNN you don't need 2000 ft of cement to seal this well, they can get by with a whole lot less (less than 40 ft) but may go for an absolute assurance that nothing will ever get out of that well again.)
UPDATE 4: (3 pm) BP are planning on injecting 50 barrels of mud a minute. Let us assume that the leaks are still allowing 5000 bd of flow, which is equivalent to 150 gal/min. 50 barrels at 42 gallons per barrel is 2,100 gallons. Let us assume, for discussion that the amount that escaping fluid through the BOP doubles during the injection. Then the flow that will go down the well is 2,100 – 300 = 1800 gallons.
There are 231 cu inches in a gallon. So they will be injecting 416,000 cu inches/minute. While the well has various diameters I will assume a diameter of 16 inches as an average. This gives a cross-sectional area of 200 sq inches (roughly).
Then the speed at which mud will travel down the well to fill it is 416,000/ 200 = 2,080 inches per minute, or 172 ft per minute. The underground part of the well is 13,000 ft deep.
At 172 ft/minute, it will take 13,000 / 172 = 75 minutes to fill the well with mud.
So that is about as fast as the operation can determine success. Though, due to pausing between steps to ensure that there aren't too many problems, it will likely be somewhat longer. And it depends on how much worse the leaks at the top of the BOP get.
UPDATE 5: There is nothing really exciting about watching a mud fountain play into the ocean for an hour or more, and so I thought I would stick my neck out a little and predict how this might end. (Nothing dramatic being visible, means that so far it is working).
Once they consider that the well is full of mud they will likely back off the pump pressure that is injecting mud into the well. They will monitor the pressure in the well as they drop the inflow pressure down, and watch to see, as the pressure falls, if there is any increase in pressure from down hole. If they can take the pressure of the pumps all the way down to ambient (which is under 5,000 ft of sea water, and is therefore around 2,400 psi) and stop injecting fluid, and nothing changes on the pressure gages, and there is no flow out of the well, then the well will have been brought under control. As the pressure in the pumps starts to fall, so the mud fountains at the leaks will start to diminish.
UPDATE 6: Well I notice that the BP Press Conference keeps getting postponed, which may be good or bad news. If the Top Kill had immediately failed (unacceptable erosion of the BOP) then there would likely have been a Press call.
If it had immediately worked then there might have been another, but that they are delaying it means that it may be working but a little slower than they had hoped.
UPDATE 7: Ah, in the Press Conference Doug Suttles said that they are only injecting mud at the rate of 20 barrels a minute. (7,000 barrels over 6 hours). This is less than half the anticipated flow (50 barrels) and they may have dropped the injection flow rate to keep pressures in the BOP at an acceptable level. That does increase the time it will take to fill the well significantly (by several hours, depending on the leak rate). Though it also shows that those estimates that the well was leaking at 100,000 barrels a day were fantasy.
It would take 87.5% of the mud injected being lost to leaks, for it to take 22 hours to fill the well, and that would indicate that the leakage rate was 25,000 bd.
I was watching CNN and Campbell Brown talked over what the biggest problem has been so we'll have to wait until either a reporter or the transcript lets us know.
UPDATE 8: Well it may be my old eyes, but I think that the flow from the leaks is definitely less than it was, leading me to suggest that the well is now full of mud, and they are reducing the flow to see if the well behaves. (8:47 pm) I haven't been watching for a little while however, but did have these other thoughts before I got distracted. (It's called dinner, if I recall).
The leaks at the top of the riser do appear to be getting bigger. However they look like crack leaks, which seem to get longer preferentially to wider, with less overall increase in flow. I would expect, since BP has more than enough pump capacity, that they will just increase the flow to balance any increase in leakage. They can monitor this through the pressure gages, and so can set the flow rate to give a certain progress down the well, or well pressure. I suspect they are more concerned about well pressure, and will just keep that at a steady value until they are sure that they have filled the well. (Probably indicated by a change in pressure levels as they start to try injecting mud into the formation rather than pushing the oil and gas back. The mud will coat the walls and make it more difficult to inject and thus they should see a pressure increase). (8:47 pm)
UPDATE 8.5: Oh, and if you were wondering why you can't see the camera feeds any longer. Oil and gas are lighter than water and float off upwards, mud is heavier and so the plume is dispersing and settling back downwards, around the well. Good job we have pressure gages. (9:07 pm)
UPDATE 9: Well the picture is clear again (wonder if they used an ROV backwash to remove the mud?) and I have looked at an earlier picture of the leak flows, relative to the current picture and I still think, from the lowering of the points at which the flows bulge out, that the jets aren't at as high a pressure as earlier. This could, however, be because the cameras have moved, or changed lenses, but the pictures do have several common features. And the heights of the plumes from both side jets are significantly shorter.
UPDATE 10: Looking at the flow now, relative to the earlier pictures it does definitely seem to be reduced. So I would suspect that they have reduced the amount they are pumping in to balance against the leaks, while they monitor the pressure in the well and see if there are any problems develop. If there aren't any (and their chance is reducing) then the plan was to inject cement and create a plug. No-one has mentioned how much of that they have available.
Incidentally, I note from some of the comments below that there is an assumption that they measured 25,000 bd of leakage. That wasn't what I said, which was that if it took 22 hours to fill the well at 20 barrels a minute, then one could assume, knowing the volume of the well, that the rest was leakage. It looks as though it took about 7 hours to fill the well, which would mean (at that assumed pumping rate) that about 60% of the fluid injected was going out through the leaks, and this comes out at about 12 barrels/min or 17,000 bd. (5 am)
Contact
- Content: editors at theoildrum dot com
- Tech support: support at theoildrum dot com
License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
HO: thanks for all your work on this, and I thought that your analogy of the plugged drain line was a good one, I had been trying to come up with one myself.
I second the motion. If there's a Pulitzer for blog leads then HO should be in the running. Excellent reporting!
If this current method of plugging the leak is turning out to be such a successful idea, why didn't they do it a month ago?
What was the hold up?
There was no hold up. In fact, they broke all records in getting such a complex and risky project going. Regardless of the outcome, the hundreds of people who worked so hard on the Top Kill project during the several weeks leading up to the attempt deserve a huge round of applause.
Keep in mind there are teams of engineers, each working on different projects at the same time. It is not as if they start from scratch when a decision is made to change course. For example, weeks ago it was the Top Hat which was the next expected attempt. Even so, there was a team working full bore on the engineering required to put the Top Kill in place.
If that has been the rate for the last 30 days, at 42 gal per bbl, that puts the spill at well over 30 million gallons of oil already in the water. Or is your figure to be taken as both oil and gas?
Cheers,
Jerry
I think it is wonderful news that the rate is 40% of that anticipated. If at twenty barrels a minute your surface pressure indicates you are moving forward (I'm certain they will do everything including another pump ship to avoid moving backward) then you have a lot of upside.
If the flowrate would have been twice the anticipated, not as much room to work to keep filling it up.
It might work.
FF
For the top kill to work, you have to have a substantial amount of pressure to force fluid down against the reservoir pressure. Working from the seawater pressure of 2200 psi down to the reservoir pressure of 13500 psi, you see that there has to be a significant pressure drop across a choke in the system somewhere. This leads me to believe that you have near reservoir pressure higher up in the wellbore which would cause your required surface injection pressure to increase to a point where I don't reasonably believe you can pressure that area up to with all the leaks.
You bring up a good point but the well could have a skin factor of +50 (inefficient sandface completion) and experience a 6,000 psi drop there.
I believe one of the BP guys said the pressure below the BOP was lower than you'd think and dropping.
FF
You could but with GoM rocks I would say that is not very practical. We really don't know.
Another issue is controlling a 14.4 ppg formation with the seawater and then 16ppg mud. They are about in equilibrium. Too close for comfort for me; I'd like a heavier mud.
That's right. If the choke point is above the mud injection point, they have a chance. Some in the previous thread said that this is indeed so.
However, if the choke point is below the injection point, they can't expect this to work. Previous cartoons showed the injection point above the rams, so I am not sure.
They can cut the BOP off and replace it with a new one. However, if they can't secure the new BOP, they risk having a completely open well, until the relief wells are finished.
sounds like its close.
http://www.reuters.com/article/idUSN2623762820100527
.
Two things:
It's clear that TOD is getting hammered. This situation must be setting a record for the site regarding the number of posts and viewers. As a former IT guy, I can bet the servers are getting kind of warm. Kudos to the techs keeping things going.
The posts/threads are getting quite fragmented. A bit analogous to our society. The solution to complex situations is more complexity. So it goes...........
Best hopes for more mud,,,,less oil.
Solving a specific problem seem to bring out lots of ideas. As to more general problems, we don't get quite as much activity.
This is a great point - The general condition seems overwhelming until it can be broken down into parts for which specific solutions can be perceived. The task of effective leadership is to bridge between the general objective and specific task.
How can you determine a kill is working with no pressure data when the flow is leaking in the riser? Its impossible, just hope for the best. Like above said you need a choke inline to hold enough pressure on the formation to not let any hydro carbons in the wellbore where its returning. If you have pumped 8000+ bbls already and still havent got it, likely not going to get it. Might as well pump until they run out and say `We tried`
I would have done a junk shot first, plug as many holes as you can. Then put the mud in hard. Not sure what they did.
I don't think you need a choke -- the weight of the mud itself is all the choke you need. After you've pumped enough mud down the hole its weight pressing down exerts sufficient pressure against the oil and gas wanting to come up that we achieve equilibrium. The mud itself is your choke.
Except that there is a choke in the hole somewhere dropping a large amount of pressure. Unless the pressure drop is at the reservoir, you probably have a large percentage of the reservoir pressure up hole which will increase your required pump pressure to get any fluid downhole.
The mud is a fluid. Adding solids prior to pushing mud would create obstructions (above the injection point) so that the mud would flow down the casing. Until there is enough mud weight to overcome the pressure from the formation, they're just pissin' in the wind. Gotta slow the wind down somehow. Golfballs and shredded tires first, then mud.
Edit: If I was calling the shots I would have had one of the relief drilling rigs punch me a hole about 2000-3000 feet below the sediment, get within about 20 feet of the casing, inject a shitload of high explosive and pull the trigger. Collapse this well and let nature do the rest. Rockman and others have said the casing is too tough. My buddy with DYNO says it's very doable. Give him access and he could push this pipe 200 feet sideways. Too far above the formation to fracture it. Too far below the wellhead to damage it. Thousands of feet of rock and mud to plug this mess. Returns it to its original condition.
I would be very nervous trying a junk shot. Two things can go wrong. Most obviously, what if you bust open the BOP? But I wouldn't want some of the junk going downhole either -although one would thing the oil flow would prevent that. In any case like everything else here, it comes down to an experts opinion about relatice risk.
The pressures on the BOP will be pretty much the same. The idea is to get enough mud down the hole to overcome formation pressure. Either way, the Bop has to hold. They know what pressure they are injecting mud (at the pumps). The junk shot would just encourage the mud to go down the casing.
Certainly an explosive can collapse the casing, but can it seal it? It is much more likely to just rupture everything and then you have a true wild well with oil and gas coming up through the mud over a wide area and absolutely no chance to control or collect any of the oil until a relief well is completed.
I don't know enough about downhole and well control to know if it might also screw up the relief well effort.
Quick general drilling question, shelburn: how does drill pipe bend to go diagonal and maintain the ability to hold mud?
I know how articulated buses hold people and bendy straws hold water but I wouldn't mind knowing how that works over a 3 mile section.
Not quite sure I understand the question.
Drill pipe is pretty tough stuff but it is not designed to bend, not very ductile. If it gets bent it is very like bending a piece of steel pipe. It will constrict and have a substantial restriction to flow, similar to the kink in the riser. If it is bent at a sharp enough angle it may crack or tear or even break in two like the riser end.
No I mean the relief well diagrams show them going down and then diagonal. Lots of other wells do horizontal drilling, down and then over.
I am asking, for the benefit of the assembled crowd of technical but non-oil people, how this bending is achieved. Is the angle so gradual over a long distance that the curvature is taken up by the pipe steel over a long distance so it doesn't matter much or is there a way that they install a u-joint or spring or leprechaun or what.
I don't know how to drill a bent hole in anything, let alone the planet.
Nothing to do with the bent riser, just a question I think many might wonder about.
Sorry I misunderstood. From a structural standpoint the curves are so gradual there is almost no extra stress on the drill pipe.
As for how they do it I believe it is magic.
I hereby refer the question to Rockman or others with that sort of expertise.
I once worked in a plant that made/renovated shoe machines. There is a type of needle for shoe soles that is almost a 90deg bend. For alignment it passes through a steel part with a long bendy hole! Apparently, one guy in another country had made them, and he had just retired.....
They use steerable drill bits. The drill pipe just follows the bit through the hole. How they precisely control the bit thousands of feet down I'm not sure. Pretty cool stuff.
I believe they used MWD (measurement while drilling) packages in the BHA. Pretty high tech stuff. Google it.
Ghung -- Techniques vary but I essentially use mental telepathy to steer. of course, you can only imagine how big my head must be to achieve such a feat.
See my bent stick analogy below. It really is more simple then many might guess. A little like the old joke about why that guy was pulling that chain down the road. Simple answer: you ever try pushing a chain down the road? The driling assembly essentially steers the DP just like a front wheel drive car functions: point your head in the right direction and your butt will automaticly follow.
Take a look here
http://www.energyindustryphotos.com/horizontal_drilling_methods.htm
I think that the API pipe threads between joints allow for some slight wiggle. A degree or two/joint.
Alan
shelburn et al -- It's all a matter of "degrees" when talking about drill pipe "bending". All DP bends but it's a matter of scale. I haven't seen a detailed directional plan for the RW but I'll guess the "build rate" (how quickly the hole angle changes) is in the order of 6 degrees per hundred feet drilled. That would mean a bend in the DP of just feet over that 100' distance. DP is more than flexible enough to handle that bend rate. If needed one can build as fast as 20+ degrees per 100". The display are shown on such a compressed scale it's difficult to see just how gentle the bend really is.
Most dramatic example of DP flexibility I've ever seen: over 30 years ago a well blew out in the Rockies and ejected 16,000' of DP out of the hole in less than a minute. Filmed from a distance it looked like a piece of string shooting out. The entire 16,000' of DP coiled around the rig in a very broad circle and the DP NEVER BROKE.
I think he's asking about the directional drilling rigs, like the two relief wells.
I think he's talking about wells which are deliberately made to slant over at some angle into an adjacent formation, like the wells the Kuwaitis supposedly drilled to tap off Iraqi reservoirs before the Persian Gulf War. I suspect the answer is the bend radius in those situations is huge -- thousands of feet at least.
What does this mean in terms a home handyman could understand:
http://en.wikipedia.org/wiki/Directional_drilling
For those that are interested in directional drilling I direct you to the following:
http://www.slb.com/services/drilling/directional_drilling.aspx
If you explore the various links you will see that there several technologies available to deviate wellbores.
These technologies should get you to within 10 - 20 ft of the target well. Special techniques are required to intersect the target well.
http://www.vectormagnetics.com/intersections_hdd.htm
Gassy – Actually it’s a rather simple design: Imagine a stick with a little bend at the end. Lay it flat in the sand and push. The stick slowly moves in the direction of the bend. Want it to go the opposite direction? Just turn the stick over (orienting the drill assemble) and push again (called “sliding” in the world of directional drillers). When sliding you’re not rotating the DP. The mud flowing down the DP into the “mud motor” causes just the drill bit to turn. Now it’s going in the opposite direction. But then how do you get that bent sub to not turn,,,,just drill straight ahead? Easy: when you start to push it quickly rotate the stick (called “rotating” by directional drillers) and it goes straight since there’s no prejudice. In this phase the DP does rotate. Want to change angle quickly: slide continuously. Go straight: rotate continuously. What to change angle slower: alternate sliding and rotating. There are other directional drilling techniques but this gives you the general idea.
@gassy
If your (non-bendy) straw was 2000 feet long, you could push one end to a right-angle to the other and a 'straight-edge' held anywhere along it would show that the straw was -almost- straight. Same thing with drill pipe.
it is rather fundamental. first of all, steel is an elastic-plastic material. that is why it is so versatile. steel will stretch elastically up to a yield point.
a string of drill pipe really is string-like. the drill string is thousands of times longer than its diameter. steel can stretch enough to bend around a corner as long as the yield point is not exceeded.
we already had this discussion relative to buckling of a riser. this riser was not designed to withstand buckling because length is thousands of times greater than the diameter in other words, acts like a string (or a cable,or rope).
try this experiment: push a rope up a hill.
if the rope is short enough(only a few times rope diameter) this experiment will work, however.
@Ghung
Submit your high explosive scenario at:
http://www.horizonedocs.com/artform.php
Desperate times call for desperate measures...August is way too far off. The Criminal Trials of the BP hand(s) who caused all this won't have even started by then.
You get up against the side of the pipe\casing they can set a shaped charge to cut strait through it or with tensil strength and pressure information crimp is closed with just a couple pounds of explosives. However all of this means you bored the relief well right up against the casing, no real point in using the explosives at that point since you can now tap and kill the well anyways.
The relief wells drill deep, almost down to the formation, IIUC. Per previous posts from Rockman, et.al., it's the last few hundred feet that takes so long. If they miss the casing they have to back up (several hundred feet?) and try again. The relief well bit has to hit the casing precisely dead center. This is what takes so much time (unless they're very lucky). Then, if I understand correctly, they have to change the bit to a special bit for cutting the pipe. My thought is if you get within 10 -20 feet and blast a cavity in the rock (that includes the casing) it will collapse and self seal, similar to how some wells collapse on their own after a blowout. This could be done farther up the well and wouldn't need to be as precise as a relief bore.
If the rock layers above the formation a very porous or fractured it may create leakeage problems. I'm still talking several thousand feet below the sediment layer. If the casing above your explosion zone is still intact (as it should be), and you could reduce the oil/gas flow substantially, the final kill pill could then be injected. Cement the crap out of everything above your blast zone. The "blast bore" could also be used to inject cement.
Worst case senario; you still have the relief wells going in far below this blast area.
Then again, I groom dogs now. WTF do I know?
Buddy of mine read that they are allowing 3 weeks once they hit the casing of the original well because it is so tricky to drill through.
Did you ever have one of those water rockets when you were a kid? Fill the little rocket with water, snap it onto the launch pad, pump the handle to build up pressure, then hit the button and WHOOOSH! up into the sky. Now that is a worst case scenario.
Update on the loop current eddy in case you were bored of watching the mud genie waft around and grant no wishes.
If can ask a question. I can see the legend and understand the surface temperature readings. Where is the overlay coming from for the Grey/Browns, which I assume is supposed to be to oil?
It is supposed to be oil. They do their own work.
http://www.roffs.com/about_cc.html
Their DWH disaster page is here:
http://www.roffs.com/deepwaterhorizon.html
LOL
I needed that.
It seems like the top kill is likely a success:
http://online.wsj.com/article/SB1000142405274870471700457526813175919368...
Suttles indicated that likely only mud is coming out, and not oil/gas.
Coast Guard Rear Adm. Mary Landry said she was "very encouraged" but added, "I do not want to express optimism until I know for sure" that the leak has stopped.
The plume of mud is "a good sign," suggesting that the fluid is exerting enough pressure to stem the flow of crude and natural gas, said Don Van Nieuwenhuise, a professor of petroleum geosciences at the University of Houston. "If the pressure wasn't great enough it would be mud and oil."
Several question on BOP design. I saw a talk about the DS Chikyu - the scientific deepwater drillship with a riser. They said that the Chikyu has a quick disconnect at the base of its riser for super emergency situations. It is a major decision, but the idea is to decouple the riser, and the ship moves off the hole [albeit with a riser hanging down]. Do GoM BOPs have this? If not, why not? Wouldn;t this have enabled some faster respose at the top of the BOP, with a cleaner top rather than the kinked riser? Some sort of deadman switch at the top, for exa?
And - why did they have to do all the underwater machining to make the couplings with the new choke and kill lines? Were they damaged? Can we assume that the new regs for BOPs that are certain to come on line will include some sort of standardized quick coupling that will allow faster connections if they ever have to do a similar kill in the future?
I'm not expert on the LMRP and BOP but there is an emergency disconnect, standard equipment if you have to leave due to a driveoff, hurricane, or other emergency. It hasn't been discussed a lot but that also failed.
It would have left a clean flange (with all the oil coming out) at the top of the BOP and the BOP would not have been bent off vertical. Probably a better situation. Single leak point, less damage to the wellhead and the possibility of attaching a second BOP.
The discussion about attaching a another BOP probably starts with trying to activate that disconnect and get the entire LMRP out of the way. That would also require removing the riser so the LMRP "top hat" is also a step in that direction.
The choke and kill lines were damaged when the riser kinked over (that also would not have happened if the emergency disconnect had worked) but they did find places they could access joints which made the hookup much easier than trying to fabricate a clamp.
It would not surprise me if they don't mandate ROV connectable fitting on the choke and kill lines as a new requirement.
Shelburn, Im not an expert either, however in this case I believe they were trying to get control of the well not disconnect from it. By the time it was realized that there was an emergency the drilling crew were dead, and control rooms destroyed.
According to some reports about the hearings there was some testimony about the captain? senior manager? yelling at a rig hand for having hit the "disconnect button" without permission. This took place after the explosions started so they had already lost the well.
This was transmitted through the media translation service so it is quite possible that it was distorted beyond all recognition, like so much else coming out of the talking heads.
IIRC testimony yesterday was that the Emergency Disconnect was activated and that they got back positive electronic confirmation from the BOP but no hydraulic confirmation. At least I think that's what I heard but I had several different feeds running at the time.
Edit: This from an AP report
http://www.guardian.co.uk/world/feedarticle/9098258
New Procedure: In certain circumstances, ANYONE can hit the BOP activate button.
Alan
I have an even better idea Alan: a full time hand to man the BOP controls at any critical stage. I've seen more than one accident caused by poorly done multitasking.
How about having a backup control room OFF THE RIG on a nearby support vessel? In the same way you don't keep backup copies of critical data on site in case of fire or asteroid strike or Godzilla attack etc.
With today's technology I believe it is possible for the BOP and disconnect to be activated from an office in Houston. But of course if the hydraulic and electronic control lines have been damaged by a fire or explosion then they won;t work no matter where they are activated.
I will not be in the least surprised it it doesn't turn out that BP, Transocean and Halliburton may have way more backed up data onshore than has been revealed to this point.
AP report mentions 2 buttons. A 'Distress' button that the one guy was getting yelled at for hitting, and the 'Disconnect' button which somebody was waiting on approval to punch.
But would they be able to do a disconnect of the riser at the BOP with drill pipe down hole?
There is another item we haven't discussed although I'm sure BP has spent a lot of time discussing it internally. It also hasn't surfaced in any of the media.
When the Deepwater Horizon lost power she lost all positioning and thrusters. For the couple days before she sank she was anchored in place by the riser, the BOP and the wellhead.
I wouldn't even want to try to figure out the forces applied to the BOP and wellhead which are only designed to take pressure loads.
I was wondering why they don't partially score the riser, so that "if the worst happens" it will bend over and kink in the middle (say) instead of right above the BOP (which seems to have happened here). I concluded that the most likely reason was, "no one expects the worst to happen".
Intentionaly weaken a pipe carrying several thousand PSI?
Actaually there is a quick disconnect system that was supposed to be engaged and either failed or was tried to late. This would disconnected the riser from the BOP and the top of the BOP would have been clear. Maybe one of our experts can tell us what is suppose to happen to the Drill string when the riser quick disconnects?
Believe the BOP shears the drill string a few feet below the disconnect so it pulls out and goes with the riser, the bottom portion falls to the bottom of the well.
yep. That is the design on the drll ship I know of; it is a last ditch, save the vessel manuver; disonnect the riser, shear off the drill pipe. This is intended to prevent the mess we have here - sinking vessel connected with the riser.
Testament to the strength of those materials... either that or pure luck. I hadn't thought of that either about her losing position keeping. This probably figured into why BP was so cautious with the lead up to the top kill. They really had no idea what the exact metal fatigue and stresses put on the BOP and the connection to the well head were. I'm sure they could roughly calculate, but it would be a ballpark. The engineers must have been sh*ttig bricks yesterday when they started ramping up the pressure in the pumps.
Two questions,
1) is there any video available from the end of the riser where the dome/funnel solution failed and they inserted the 4" pipe?
2) do we have any information from the 4" collection pipe? Did it stop collecting because the mud is heavier than water? Is it still collecting gas?
Haven't seen or heard anything on either of these since the top kill went live.
Thanks,
Tim
I believe a post in an older thread indicated that they pulled it when the top kill started.
The 'siphon' was removed before the top kill. The video from Wed. morning showed this. They have two ROV's at the BOP location. One is watching the top of the riser leak at the BOP and the other is above this one looking over it and the BOP. One of these would have to drive over to the end of the riser to see the other end.
Liveblogging Top Kill:
http://www.washingtonsblog.com/2010/05/liveblogging-top-kill.html
never mind
Is there still a feed showing the end of the riser ?
Looking if oil is still coming out there or not would be a better indicator of success or not than what is coming out of the BOP leaks no ?
Is there room below the BOP for a wet tap?
HO - First off thanks for all the updates, very interesting and great to have a reliable source of information. Could I ask a favour.....When you do the updates on the original post could you put time and maybe the date on there so we can get an idea of the timescale?
And while i'm on....thanks to all others (Rockman, Shelburn, FF etc) who have provided insight over the last few weeks.
A screen shot of the leak at the riser kink with an ROV for scale. You can see how close up they are filming. It looks a LOT more manageable with something for reference.
Roughly how big are the ROVs?
They come in several sizes. Check out this site: http://www.oceaneering.com/rovs/maxximum-rov/
Double post.oops.
What's going on with the Enterprise 1 ROV in the CNN feed? Looks like some sort of venting or a leak.
Looks to me that they are monitoring the riser carrying the mud down from the surface. I doubt those are leaks. Probably just sediment kicked up by the ROV thrusters.
On twitter people are saying that Fox News is now reporting that BP officials have said they have stopped the flow.
Looking at the live images I still see as much mud coming out of the top of the BOP. That would tend to imply that the pressure is coming from the well which would be bad news. Is that correct?
Could be bad jean. A well in this situation has only two states: not flowwing because they've gotten enough head from the drill mud to put enough back pressure on the reservoir or the well is flowing and that will pdump back out every bbl of mud they've pumped in. The big question is just effective is the seal between the drill pipe injecting mud and the top of the BOP.
deleted
As the pipe tries to make the turn from the vertical to a more horizontal direction, the outside diameter of the pipe cycles from tension to compression due to the rotation of the pipe in the bore. As long as the stress in tension or compression is less than the fatigue limit of the steel pipe, it could rotate indefinitely without fatigue. This is much like a rotating shaft on a pump, compressor, etc. The shaft is never perfectly straight so it cycles between compression and tension. If the stress in bending or tension is less than the fatigue limit, the shaft should not fail. Aluminum on the other hand will fail after a certain number cycles.
The curvature of the pipe while drilling should match the fatigue limit of the steel. I’m not an expert in this but I would push the stress to the fatigue limit with very little safety factor to get the curvature. Pipelines design to the yield to reduce weight whereas offshore piping will have a safety factor I believe three. As the pipe moves past the curvature it will straighten and fatigue would probably be less of a concern.
This is way oversimplified because the torsion stress and stress due to weight should be also included.
Note: Live discussion has moved to http://www.theoildrum.com/node/6115