Deepwater Oil Spill - evidence of erosion

There was, apparently, no briefing today on the Deepwater Oil Spill. However RockyPaloma has put up a number of videos on Youtube showing an internal video inspection of the blowout preventer (BOP) with pictures of severe metal erosion.

Erosion within the BOP (RockyPaloma )

Some of it seems to have eaten around the plate of the shear ram, in at least one place, though I have not watched this in real time and am not sure of all the locations.

Possible erosion of the BOP wall around the shear ram plate. (RockyPaloma)


The video sequences include one of the shear ram plates retracting )

And one showing the deformed drill pipe surrounded by the eroded annular preventer, gives some indication of the extent to which sand in the oil/natural gas/water mix was eating out the internal surfaces of the BOP, and allowing the leak to increase in size, over time, a point that I made, quite early in the proceedings.

MoonofA has given a more concise, yet comprehensive picture of what the camera saw, together with a sketch of the ram assembly showing what the various parts are that are shown in the video. Ricx also adds an interesting question.

For those who need reminding of the structure of the BOP, PhilMB has put up a graphic section of the structure, so that you can tell which view corresponds with what.

The problem, of course, is that it is not clear when the different stages of erosion occurred. While there is some, there is not a lot of difference in wear surface patterns under differing flow regimes, containing different abrasive concentrations at different flow speeds. Because the erosion took place over the relatively long time intervals that it did, I am surprised in a way that it did not do a lot more damage than it did. Certainly some of the gaps might have been filled if the top hat “junk shots” had been continued longer than they were.

View of the crushed DP with surrounding erosion (RockyPaloma)

The investigation is, however, still in its early stages, and I imagine that there will be a lot more expert testimony on the structures (which likely means that at some time they will be cut apart to provide sectioned specimens). That is not going to be a simple short-term operation or investigation. And at the same time the pressure is now no longer on the relief well to seal in the oil and gas, so that too is likely to proceed at a gentler pace.

Deepwater Oil Spill - BOP on board

First it was hoisted to the surface

Note the actual size of the Deepwater Horizon Blowout Preventer as it is held just above the support frame, after having been raised through the moon pool of the Q4000. Compare the size of the folk standing around. (The BOP is the large frame with the yellow legs on the corners, being held just above the red platform with the four vertical bracing colums).




And then it was lowered and latched into place on the red platform, that can help to move it and support it.

Meanwhile the LMRP that sat above the BOP is still on its way to the surface.

Deepwater Oil Spill - changeover completed.

Well, in one day the progress on the Deepwater Horizon moved significantly further towards the end. First the capping stack was removed from the well, and then, after a strong initial tug on the BOP, and transition spool, they were unlatched and moved away by the Q4000. As they left it was clear that there was no pipe, or hydrates under the BOP, though there was a thin film of a liner inside the BOP mount. This was then cleaned off, and a new gasket inserted. Once that was in place, then the new BOP (from the second relief well) was brought to the well, and lowered until it into place. (There is a Youtube video of the separation with the mount and BOP clearly separated by 3 minutes into the tape.)

Waiting for the new BOP

There was no drill pipe under the BOP, when it was lifted, nor any evidence of one or of any hydrates in the casing of the well itself. Thus some of the concerns that I had turned out to be unwarranted, but we did not know until the BOP was gone, what the conditions were likely to be. The next step in the process is to ensure that the BOP is working properly, and then the relief well will be completed at the beginning of next week.

With the "new" BOP in place.

That will likely be when we find out whether the annulus between the production casing and the well liner is full of oil or drilling mud. Given that a number of my concerns over the condition of the well have turned to be worse than the actual condition, I think I will hold off, at this time, on making any on that one.

Deepwater Oil Spill - stack off, but another incident

Once again I am indebted to MoonofA, who is giving a more detailed hour by hour report, of some of the incidents that I miss. Fairly rapidly on Thursday afternoon, the team of ROV’s and surface vessels moved forward with the removal of the existing infrastructure over the Deepwater Horizon well, with the intent of replacing it all with a functioning blowout preventer from the 2nd relief well (which now looks to be no longer necessary at all). One of the first steps was to move the methanol feed (used to dissolve and remove hydrates from the internal structures of the stack) down from the rams of the top stack to feed into the original BOP. This was used to ensure that the different parts of the stack, such as the rams, were able to function, when needed. And now, I presume, the hope is that it will similarly ensure that the BOP rams can function if needed.

Removing the line from the stack


Replacing line on the BOP

Once the feed line had been moved, then the Enterprise came in and lowered the latching device that has been floating just above the stack for the past few days. It did not take long (and by doing so did not convey the difficulty) to drop the cap over the top end of the stack, and not long thereafter the stack was released and lifted away from the underlying transition and the original BOP.

Approaching the stack

The more interesting part of the exercise will come when they start to lift the original BOP and the transition spool. There are a number of different scenarios that have been proposed, depending on what happens, and why, as the first lift begins. If they can lift the BOP with the underlying drill pipe (DP) still attached, then they appear ready to grab hold of the DP after the BOP has risen a short distance, and cut it off. This will make it easier to get the BOP to the surface, and means that a more conventional fishing tool can be used to capture, and bring up the remaining length of the DP. Toolpush, for example, mentions some of the options available.

Sliding into place

The capping stack was released at about 4:30 pm Central, whereupon Admiral Allen issued the following statementz:

"Under the direction of the federal science team and U.S. government engineers, BP has completed the capping stack removal procedure – an important step in the process to remove and preserve the damaged BOP. This procedure was undertaken in accordance with specific conditions I set forth in a directive authorizing the capping stack removal and BOP replacement last week. BP will continue to follow these required conditions for the BOP removal procedure, which is expected to commence this evening. I will continue to provide updates as necessary."

One of the problems with the feeds from the Q4000 is that they are not time-stamped, so that it is hard to know if the latest glance at the feed below the moon pool, which shows that the pipe hasn’t moved since I last looked, is current or not.

The other significant news today was of the fire on the Mariner Energy platform in the Vermillion block of the Gulf of Mexico. The fire now appears out and there was apparently no leakage from the wells that were connected to the platform. The platform is in 340 ft of water, and was fed by 7 wells collectively supplying 1,400 bd of oil and 9.2 mcf of natural gas, that is now shut in.

I note that they were apparently waterblasting the rig and repainting it. One of the things to be careful of in those cases is the static electric charge that can build up in water vapor around the operation. From the Coast Guard report:


However, at this time, that is just conjecture, and we will have to see what the investigation reveals.

Deepwater Oil Spill - preparing to move

The annotations to the ROV feeds from BP are becoming a little more descriptive, particularly with those related to the Q4000, which will be playing a significant part in the replacement of the blowout preventer (BOP) on the Deepwater Horizon well. However, at 9 pm on the 1st, with the waves still a little higher than desired, the activity has yet to start.

One of the new camera feeds that is being displayed is a weight indicator on the deck of the Q4000. This is not yet on line, but Admiral Allen pointed out on Wednesday the loads that will come onto the vessel.

We anticipate removing the blowout preventer with the latching mechanism that will be attached to a drill pipe string that will be suspended from the Q4000. . . . . . .

The combined weight of the drill string, the latching mechanism and the blowout preventer itself is approximately a million pounds. When they released that blowout preventer from the well it will be suspended at about 5000 feet below the surface.

There are two things we’re concerned about when this occurs, number one is the wave height. You can imagine the Q4000 riding up and down on the waves. When they ride up it exerts more dynamic loading on that pipe system. So we’re concerned about the weight and the ability of the pipe system to handle that.

Before the BOP itself is removed, the capping stack has to be taken off. The latching mechanism to attach to that is already down underwater, and is being monitored by the Enterpise, through ROV2. The stack will come off first, and it is that activity which is now expected to start at noon on Thursday.

Once the Q4000 latches onto the original BOP it is going to raise it up, through the platform of the vessel, and then set it back down on that deck. There are two additional static cameras on the Q4000 which are monitoring the moon pool, and which are presumably going to be carrying all this activity starting tomorrow and running perhaps 36 hours, depending on the weather and how easily the BOP assembly breaks away from the well.

As soon as the Q4000 has the BOP on board, it has to move out of the way (and trans-ship the parts of the BOP, once separated to smaller ships to be sent ashore) so that the new BOP can be put in place.

This is the task for Development Driller 2, but before the job is finished the BOP has to be thoroughly tested to ensure that everything is now functional, the BOP will then be ready for the final stages. At this point it will be possible to restart the relief well to complete the bottom kill. That is still not anticipated to start until after Labor Day.

I am going to insert the quote on what the Admiral said on hydrates it its entirety, since I am not sure exactly what his point was.

Hello, Admiral. Can you tell me how the current BOP is attached to the well head and if there’s any concern about hydrates or other (inaudible) that might make it difficult to latch?

Thad Allen: Well, the current BOP is attached to the wellhead with the same connector they would use for any similar drilling well. To the extent that hydrates are there, we don’t expect that to be a problem right now. Had we continued to try and fish and get the pipe out of there, there was some concerns that hydrates would be blocking our ability to use a camera and actually operate down there. So I’m not sure that’s an issue. If there’s an issue at all, it’s probably the issue of the condition of the wellhead itself. When the Deepwater Horizon exploded and sank it bent the riser pipe over and ultimately the riser pipe was severed from the drill rig. At that point, if you can imagine, as massive as the blowout preventer was and that wellhead was, it probably bent over to some extent and then when the riser pipe separated from the rig it popped back up. It did not pop straight back up and there’s been some attempt to level that, to make sure we could get that as close to vertical as we can. I believe the current estimate right now, it is about two degrees off center line. So as we go in to pull the blow out preventer out, I would say hydrates are not a real big concern. I think the alignment to the true vertical about two degrees off would impact somehow to a very small degree the pull on the BOP as you’re trying to free it. We are aware of it. The engineers have taken that into account. We don’t think it will be a prohibiting condition, but it is something we are aware of.


In the other story that I have been watching, that of the miners in Chile, the equipment has started, and the preliminary drilling of the central shaft is now down more that 20 m. At the same time the rescuers are considering ways of reaming one of the smaller drill holes that have already reached the area. This might take a greater number of stages to get the hole out to the required size, but could, in total, be faster than the two-stage operation that is currently in progress. In either case moving the muck from the bottom of the excavation with wheelbarrows, and ensuring that none of it gets stuck as it falls from the machine, are both concerns that will have to be addressed as the work moves forward.

Deepwater Oil Spill - another weather pause

The weather is currently holding up the proceedings at the Deepwater Horizon well site. The seas are some six to eight feet, which is apparently the height of the top 1/3 of all waves. (There is a table that shows how it is affected by wind speed, duration and fetch, which last is the surface area that is being affected by that wind). There is a site with a post on wind basics that explains). So the underwater effort is likely to be put off for another two to three days (depending on how Earl behaves, though it's not supposed to get close, but it might. The current problems are more local to the Mississippi Delta). So there will be a delay for at least a couple of days until the water settles down a little more. The problem is caused by the considerable length of the risers and cables on which the large steel structures sitting at the sea bed will ride as they are moved about. With the waves lifting and the swells rocking the vessels there are risks both from the changes in dynamic loading, and also in generating a pendulum effect as the weights sway. Much better to pause a little longer.
At his press conference today the Admiral described the plans for the next step in the process:

the Discoverer Enterprise (will) remove the capping stack and then back off. (At) that point (the) Q4000 will come in and lift the blowout preventer (BOP) which will also (hold) the transition spool which was put in to accommodate the capping stack. And a third step will be (for the) Development Driller II, which is drilling a second relief well, (and which) will move in with the new blowout preventer, and put the blowout preventer on.

Once that blowout preventer is in place, the well will be in a position to withstand the pressures expected on the intercepts of the analysts by Development Driller III and the drilling mud that will be forced in there when that happens. All is in readiness, and at this point we are just standing by for a weather window.

In discussing the current thoughts on why there are three pieces of pipe in the BOP, the Admiral also explained where his concept of the the pipe being fragile was generated.

When we first were looking at the riser pipe, if you remember, there was a kink. And then we were looking to cut the riser pipe, and we made a shear cut. And then we actually unbolted the stub that was bolted to the flanges before we put the capping stack on. At one point, we actually saw two pieces of pipe.

The original presumption at that point, and this is a long time ago now, was that a part of the pipe had fallen down into the Lower Marine Riser Package, and it was alongside a pipe that was extending through the centerline down into the BOP. As we have gotten into the blowout preventer itself and taken a good look at it, we found out that that pipe is fragile, is broken into three pieces, and we no longer have a pipe that's suspended in the centerline.

So our assumption is, our original assumptions on the pipe – and at that time they actually might have been. These pipes are being subjected to a lot of different forces in there. If you remember, we've had the dynamic kill and the static kill. There have been a lot of different fluids that have been forced through the blowout preventer or the capping stack, Lower Marine Riser Package.

In general, we have concluded that the pipe is of extreme fragility. And while we could try and recover it, the pipe that we can get to right now is not connected to any pipe that is on the (center) line. It could extend out into the BOP. So for that reason we just foregone any more fishing experiments, and have gone directly to remove the blowout preventer.

If I understand this correctly the current thinking is that none of the pieces of pipe above the shear ram are being held by it, and that they are less consequential as a result. Whether that also means that the DP was actually sheared in half by the ram is a different question, but apparently not one that the current investigation is going to look at further at the moment.

It does, peripherally suggest that there may not be any pipe now below the rams. Because if the different treatments that have caused the pipe to break into these bits did so across the shear ram plane, then there may not be enough holding the pipe below the BOP and it may be long gone. The gamma scan that showed the DP was there was, after all taken very early in this process, and much has happened to the well since.

The Admiral also noted that the drop in pressure (from the anticipated perhaps 9,000 psi) when the well was finally shut in is now believed to be due to reservoir depletion.

Oh, and for those of you admiring the ability of those on the platform to fish, the Admiral noted that the team involved in those operations included BP, Schlumberger, Transocean, Cameron and Baker Hughes personnel.

Incidentally I also think there was another transcription error (I tried to smooth some earlier ones by interpreting the words transcribed with my own (in paren, within the quotes). In dealing with the question of whether the DP is still there, and if it is held in place with either hydrates or cement he said:

The answer is I don't think we know. You know we think there may be a chance the pipe might have adhered to cement during the static kill process. We don't know that to a virtual certainty. But we don't want to try and pull the blowout preventer without having a contingency ready to deal with that eventuality.

So what we're doing is, we're going to life the blowout preventer. If it doesn't come off easily, we’re going to apply 80,000 pounds of lift. And maybe somewhat of a mis—we'll calling that the gentle pull. If for some reason that does not free the pipe then we will go in and mechanically open the rams and lift the blowout preventer out over the pipe, and then we'll share the pipe with the wellhead.

I believe that last ‘share” should be “shear” and will, actually, more likely be a saw cut.

And the small flow of bubbles from the stack, which the Admiral feels inconsequential, as earlier such flows proved to be, is still going on.

Deepwater Oil Spill - stopping the fish

The attempts to recover pipe from within the blowout preventer (BOP) on the Deepwater well have now halted, without being able to recover any of the pipe. Instead attention is now being given to the removal of the BOP itself and its replacement with the BOP from the second relief well. In his remarks on Friday Admiral Allen gave, as his explanation:

What we have found is we have gone down there, the pipes have settled against the side of the BOP and we can't successfully put the overshot devices over them. We've come to the conclusion that any more attempts at fishing are probably not going to result in success.

And at a meeting this morning between our science team and the BP engineers it was decided to recommend to the principals, the cabinet secretaries we go ahead with the removal of the blowout preventer and the replacement of the blowout preventer with the one that's on Development Driller 2.

This is due to the one whose apparent fragility of the pipe that keeps breaking and falling off to the side and also the unknown condition of the BOP below that and I can talk about that in a little bit.

So the plans are right now to replace the BOP. The approximate timeline going ahead is as follows, starting today and through Saturday and Sunday we will make preparations to remove the BOP and replace it.

This did not agree with what I saw occurring during the time that I watched both the recovery attempts over the last two nights, and from the videos that others posted on Youtube, and which I referred to in those posts. However, not being a part of the team running this operation there may have been some things happening that I and others are not aware of.

I still remain concerned about the condition of the lower section of the BOP and the presence of either hydrates or cement, both in the area of the BOP rams, and around the drill pipe as it extends down into the well. To explain the concern in perhaps a little more detail, let me first talk a little about the casing hanger that the Admiral referred to as one of the limiting well conditions today.

The casing hanger is the device at the top of the well that holds the production casing in place. In the extended transcript of his press conference on Friday, he referred to the company that made the hanger (Dril-Quip) and gave a link to the drawing of the hanger, this one, which I have labeled, because I am going to try and explain, using this and other diagrams, what the Admiral meant with some of his remarks, as I interpret them, and some of the concerns I continue to have.

Labelled section showing the parts of the casing hanger (note that there is an animation at the source site)

In essence, at the top of the production casing, the long continuous tube that was placed from the sea bed down to the bottom of the well, there is a hanger that holds the top of the casing against the surrounding liner and well head assembly. To show that in more detail I am going to use a different source, to highlight the hanger section.)

Casing hanger.

The casing comes up through the center and connects to the top element. The weight of the casing now pulls the upper section down, seating the conic surface, and also spreading the elastomeric packer (the black layer) which pushes out against the sides of the surrounding wellhead wall, providing the seal. This seal is between the liners around the top of the well, and the production casing, it is, in other words, the seal at the top of the annulus between the production casing and the wall of the well.

I have put this in to explain what the Admiral meant when he was talking about trying to lift the BOP off the well head, which means unlatching it from the top of the well head assembly. The BOP latches around the top of the assembly shown in the top figure.

To remove the assembly, the Admiral has approved the following process:

Commencing on Monday and through Tuesday the Discoverer Enterprise will latch on and remove the capping stack. And the capping stack will be temporarily stored nearby on the ocean floor. Once that has been completed the Q4000 will move in and connect to the BOP and will unlatch it.

And then there'll be a series of two decision points will occur. We will attempt to pull it free and we are prepared to apply up to 80,000 of force in addition to the weight of the blowout preventer to lift it. We call this the gentle tug.

If the blowout preventer comes free we will then use the (Boa Sub-C) and the ROV's to attach a line to it and cut it (the drill pipe) just above the well and at that point we can bring the BOP to the surface on the Q4000.

If for some reason the blowout preventer does not come free with a gentle pull, our intention then is to manually open the ram sequentially down through the blowout preventer and then raise the blowout preventer and cut the pipe at the well head.

He later explains why there is this limit of 80,000 lb in the “gentle pull.”

What they’re concerned about is somehow potentially dislodging the hanger and the casing hanger that is at the top of the well. That is also the – as you know that is a device that contains the seal between the annulus and the well and the blow out preventer. So the threshold for the pull has more to do with the potential to unseat the casing hanger and the seals that seal off in the annulus.

So that if you go back to the second illustration, the seal is maintained by the weight of the production casing, pulling the head of the hanger down so that the elastomeric seal spreads. If the upward lift on the BOP is transferred through the drill pipe to the top of the casing, they are concerned that if the DP is held within the casing hanger, that pulling it too hard may take the weight of the seal, so that it contracts back from the wall, and opens up the annulus.

Now to explain why that might happen, and why there might be all sorts of other concerns, let me move away from the hanger itself, and go to a modified frame from the Dril-Quip video. (For those looking at the video I have changed the picture to show the center as though it were the drill pipe).


To make life easier for me I am just showing the lower end of the BOP, below the rams, the central drill pipe and the upper end of the well head (without the hanger detailed).

Now in a normal situation the drill pipe would be held by the three rams at the bottom end of the BOP, and slightly above the picture. In an ideal world there would be nothing else in the gap around the drill pipe (i.e. the annulus).

But we know that above the rams, that there is either hydrate or cement around the DP.

View from the fishing camera showing the top of the drill pipe above the BOP rams, surrounded by what may be either a hydrate or cement fill.

And the pipes are held and seem unable to be moved

What we know is, the pipes that we can see are in pieces, sitting inside the lower marine riser package and we are having trouble lifting them out with the fishing devices. We have no further information and cannot tell the condition of the pipe below the blowout preventer.

If the material holding the pipes extends down into the rams of the BOP and below it could fill the upper annulus down through the casing hanger. Thus pulling on the BOP would exert a pull, through the DP and this fill, on the hanger and could unseat it.

Should the BOP not move, the plan is to open the rams on the BOP, so that it no longer holds the pipe. But if the rams are cemented in place by the fill, this may be very difficult to do, since trying to flush out that fill on Thursday evening didn’t work. And even if it did work, the fill may occupy the annulus between the BOP and the DP below the rams and above the latch, so that the DP is still held by the cement. (At which point if the chemicals don’t release it they might try the jetting again, since that works both on cement and hydrate). It is only by freeing the BOP from the drill pipe, and hoping that the pipe remains held by the underlying fill within the hanger, that the BOP can be released, removed and replaced.

The problem is that if, when the rams are opened, the cement/hydrate holding it is not strong enough, then the pipe may fall to the bottom of the well, carrying with it the evidence on what actually happened to it within the BOP. (Opening the rams will also drop out the other two pieces of pipe currently above the rams). Tough decisions.

Deepwater Oil Spill and San Jose Mine concerns

There has not been much apparently said about the fishing for pipe within the blowout preventer (BOP) at the Deepwater well today. The project seemed to come to a studious pause with the discovery of a considerable volume of hydrates around the shear valves in the Deepwater BOP, as opposed to the lesser quantities of hydrates in the 3-ram stack that was placed on top of the well, as part of the shut-in procedure.

The interlocking crystals appear to be filling the empty spaces just above the rams in the BOP, and holding the pipes in that space with sufficient tenacity to make them difficult to remove. If that is indeed the case, and the crystal growth extends down through the BOP and into the spaces at the top of the well then it poses a potentially significant problem to the extraction of the drill pipe, and the removal of the existing BOP. The current BOP needs to be replaced so that a functional BOP can be placed in its stead, and the well can be conventionally plugged and sealed and then abandoned.

However, if the hydrates have extended down through the mechanism and space of the BOP, then, as with the upper set of rams, the moving parts of the BOP may no longer be functional, meaning that the drill pipe cannot be released. This then raises a further complication, since if the drill pipe continues to extend below the BOP (and it is believed to extend some 3,000 ft) it too may be held within a hydrate plug that fills the space between it and the steel and cement rings that form the upper lining of the well. I will probably explain how we use that principle in bolts that hold the mine roof up around the world that are often called full-column resin anchors, in a Sunday tech talk fairly soon, but the net result is that the BOP and drill pipe may be locked in place.

This makes the next step in the process somewhat difficult to predict, since the intent in removing the BOP was both to allow the well to be plugged, but also to provide a backup protection for the top of the well, at the time that the relief well drilled into the lower part of the well, and where the changing pressure condition at the bottom of the well might cause the seals at the top of the well to rupture and, with inadequate protection at the bottom of the well potentially allow the well to start leaking again.

While this consequence is somewhat unlikely, it depends on the condition in pieces of the well that are not available for inspection. Hydrates above the shear ram suggests that it is likely that they extend below the rams, but there is no way of knowing without clearing the passage. And the extent, or even the possibility of the drill pipe being held within a plug of hydrates is not that much different to it being held in a cement collar that adhered as the cement was pumped to the bottom of the well.

The hydrates above the ram could be removed (either with the high-pressure jetting or chemical/thermal soaking) but it may be more difficult to get through the BOP to release the underlying catch holding it within the sea-floor mount, and to release the drill pipe, or even to section the drill pipe to release the assembly. And just before midnight (as I did a last check after writing this post) they started flushing the BOP with some fluid.


Moving down to Chile, the machine that will be used to drill the relief well is a variant on a raise drilling machine, that is used more commonly for boring holes upwards from the underground space, rather than reaming them down. It is a Strata 950, made by Murray and Roberts through RUC Cementation. The unit, was, apparently, only built last year.

RUC Cementation has established the capability to design and manufacture specialist large diameter raise borers in its Kalgoorlie workshop. During the year (2009), three Strata 950 raise borers (the most powerful underground raise drill rig in the world) were completed, one for its own use and the other two for group operations in South Africa, Canada and Chile.

Raise borers normally work by drilling a small hole (13-inch diameter) down from the surface to an existing underground space. Then a reaming head is attached to the drill steel at the bottom of the hole, and the head rotated and pulled back up the hole, allowing the debris to fall into the larger hole below it. It is a relatively fast and effective method of creating shafts, and is increasingly used at the surface and in underground mining.

Normal use of a raise borer .

In some cases, such as the present one in Chile, it is not possible to get the larger reaming head down to the bottom of the shaft. In that case, once the initial central bore has been completed, then a second reaming head is mounted and will drill down along the same line, with the debris still falling down the central hole, and being disposed of underground.
This alternate way of drilling is not as fast, since the operation has to be careful not to block the borehole with the cuttings from the reamer, and it is a little more difficult to keep going straight. The following two pictures are of a competing model but serve to illustrate the principle of the Down Reaming process:


In contrast to up-reaming the drill shaft is in compression which might help on longer bores. One of the drilling requirements is to watch the torque that develops in the drill rods, since this can build-up to sufficient levels that, if suddenly released (as in drilling broken rock) it can whip the head around sufficiently fast as to break the string.

The actual teeth on the bit are specially designed for the rock that the bit will be expected to penetrate, but they are conventionally bit or button teeth, similar in shape to those used in the smaller cones of a conventional oilwell bit.

Reaming head being loaded into place.

The drill will operate from a concrete pad, which is, I gather, now poured, but must set before operations can commence tomorrow, and the hole is not planned to be lined, which may also cause problems, since there is no easy way to deal with rock that falls behind the head. However this particular one is called “David” so let us hope it can meet all challenges.

The Strata 950.

I do have a couple of other concerns. One is that the miners were apparently getting water from an underground stream, and one worries as to whether this water leaves the mine though an existing natural channel, or if it has been flowing to the bottom of the mine, where it might have been earlier collected and pumped out. If the sump pump no longer has power, this could imply that the mine is slowly flooding. And in that regard, the decision not to send power down into the mine, means that they could not send down and power small pumps that the miners could then use to keep their current location dry.

Deepwater Oil Spill - Recovering pipe

The problem with not watching the video feeds from the ROVs at the Deepwater site on a very regular schedule is that it becomes hard to define if anything has changed since the last time you looked. At 11 pm Central tonight, for example, the feed has switched back from the downhole camera to the ROV camera on the Boa Sub C ROV1, and the borehole feed shows that the pipe containing the camera seems to be dangling in the water, as it has been some time ago. So it was not clear from the suggested cameras as to the current status of the fishing attempts to remove the different length of drill pipe (DP) which are still within the BOP and the stack above it.

However, switching to the Enterprise ROV1, suddenly there is a piece of pipe being examined. It is difficult to tell exactly which piece it is, though it is apparently marked in what may be foot intervals, but the examination at the moment is focusing on the end of the pipe, which is the male end of a pipe section, and it is hard to determine whether the threads have been damaged or not. (This is being written as this occurs). MoonofA has an explanation (this was part of the fishing string) and I will add that comment below the fold and the current pictures.

Close-up of the lower end of the pipe

Earlier the pipe had rotated so that an identification number could be seen:


The pipe has a number of spaced marks on it, with five marks higher getting to 70
(suggesting the other side of the joint might have carried a 5).


The mark just below the point where the pipe section goes into the end of the fishing tool that caught it reads 90, and then there are three individual marks and the fishing tool holding the upper end of the pipe section.

Hmm! That’s interesting they have just apparently driven the open end down into the mud:


So that they could release the top and go and look at it.

And it appears, at first, that this was the piece of the pipe that was cut through by the diamond saw that the Admiral referred to in his press briefing.But then they do a close-up of the top and it is the female section of the joint at the other end of the drill pipe.

Upper end of the drill pipe

And this too gets a close examination of the threads.

MoonofA's explanation of this is:
That part of the drill string fell off from one of the two fishing strings the Discoverer Enterprise had brought down. Pretty embarrassing for the crew to lose some 30-60 lower feet of the drillstring with a fishing tool on it only to have to fish for it later on ...

Here is a video by RockyP showing the lost part standing vertically in the mud.

But the Discoverer Enterprise has two derricks and the other derrick had another pipe down with a fishing tool and with a cam inside it. That pipe went down and looked for "fish" inside the stack: Video by Naula.

The first fish found at a depth of 5015 feet was the longer piece of broken drillpipe with a squeezed end and they actually tried successfully to get it inside the overshot tool. But when they yanked the tool up the fish escaped: video in double speed by me.

The camera then went further down and at the height of the flex joint at 5026 feet depth found this:


We are seeing the inside of the flex joint from the camera in the fishing tool. There is in the center-right an open piece of pipe. Next to it is some rough space open where fluids come through from below pumped by the Q-4000 through the choke line of the BOP. At the top of the picture another pipe can be seen which extends above. Both pieces are probably held back by what appear to be hydrates (though this could be just loose "beehives" of hydrates or something else).
Hard hydrates would explains why the first attempt to yank the longer caught fish did not work. It is probably held back by hydrates on its lower end.

The fishing trip has ended for now.

The big question to us at #theoildrum is: How did hydrates form so deep inside of the stack? When was there seawater as well as methane, both needed to form these hydrates, in the BOP and stack at the same time? Or do we see something different than we think?

Heading Out comment - they did remove some of the hydrates using a high-pressure jet earlier in the work, and this should still be down there, so they may go in with a lance to clean out the hydrates, but if they exist throughout the lower BOP then the entire assembly may be frozen in place, and if this extends down into the casing of the well, then as I mentioned in an earlier post, trying to pull up the drill pipe, and even recover the BOP may be halted because they will snap the drill pipe before they will be able to break it loose. Alternately they could try flooding the area with chemicals again.

Earlier in the day Admiral Allen explained some of the events that I discussed in yesterday’s post, noting that the rams in the stack had become jammed because of the formation of hydrates within the mechanism, that then led to them freezing as the hydrates were disturbed. BP then chose to flush the system again, using an antifreeze solution.

Question: What chemicals were used in the recent flush to remove hydrates?

A. BP used a methanol soak as the predominant medium for melting the hydrates. They also circulated MEG water - methyl ethylene glycol (antifreeze) - to help improve visibility conditions.

Q. Will there be ROV feeds available to observe the pipe removal?

A. BP will have the regular suite of ROV's on scene for the operation and the pipe extraction should be visible through the Enterprise ROV camera.

With the problem of the ram movement in the capping stack having been resolved, the plan for the day was to go down inside the stack to recover the pieces of pipe that had been found. One of these is relatively short (about 18-inches long) the second (and here the Admiral corrected a length given earlier) is some 13-ft long, and then there is the section of the DP itself.

Now the segment that appears to have just been removed would be 30-ft long if it were a standard length of DP, so I am wondering if this was a transcription error in the relevant paragraph of the teleconference?

The other issue dealt with by the Admiral dealt with the possibility that when the cement was pumped down the well it might have adhered to part of the drill pipe, and filled a gap between it and the production casing, so that over some unknown interval the DP might be effectively glued to the casing. His comment

We believe we can easily remove two of those pieces of pipe because they're standing free inside lower marine riser package. After that, we will have to determine the condition of the pipe extending down into the blowout preventer, if it goes below that down into the well, if the pipe somehow might have been cut and is suspended there and it was cut below the blowout preventer, there's no pipe we do not know any of that right now because we cannot see down there.

We are creating alternatives that will allow us to either remove the pipe if it's removable. And if it is not, plans to how we were remove the blowout preventer with the pipe attached and bring that to the surface and cut the pipe at some point. Our science team and BP engineers continue to work with all those alternatives as we move forward. We are hoping however to remove the two pieces of pipe and have a better idea today or tomorrow about the remaining piece of pipe.

Unfortunately, not having watched earlier this evening I missed the section of pipe falling off, and what led to the sequence of events i described above, where the two ends of the pipe being examined were, in fact, at one time joined together, rather than being the one section of drill pipe that I had initially thought that they were.

Deepwater Oil Spill - More questions than answers

Hmm! So what is going on at the well? On Tuesday evening there were a couple of posts in the comments at TOD, one of which showed oil leaking past the shear rams in a BOP, as a Youtube segment, (H/t TOB ) while the second was a short clip showing the shear opening (H/t Chuck Schick ) . Because of the bandwidths involved I am just going to take a couple of frames from them to show the situation. This is from the Youtube segment:


This is a different shot from the one shown in a loop by Chuck which includes this frame:


And then there was the ejection of what appeared to be mud from the stack at about 12:41 pm that (H/t MoonofA) is also on Youtube.



Which leaves one wondering what is going on? Did the DP fall and rupture the casing and this is flow from the annulus? Has the seal at the top of the annulus lost its integrity? Is this oil, gas or some combination – since mud alone would be denser than seawater and should sit in the well without a problem, given the testing that was done at the end of last week. Is this perhaps some residual fluid in one of the lines that was being flushed out, and if so which one?

There are (and I am writing this around 10 pm Central) it seems two borehole cameras. The official one, which is swinging in free water it appears at the moment, and that from the BOA Sub C ROV1, which is the feed that is showing the ram blades and the flow. Unfortunately (unlike the main ROV cameras) this is not date stamped, so that when I just went back for a check the view is relatively quiet with no flow and the valve open – so this may have been another unwarranted alarm. But it would be nice if, perhaps, the Admiral could explain this. (At the moment the listing of the Transcript of the press conference for Aug 24th reverts through a link to the Transcript from the 23rd).

In regard to the events in Chile, now is not the time to talk much about the rising price of metals and other minerals that come from underground – their depletion and the problems they cause are more the subject of the more conventional posts that we write at this site – but I did note the comment on the price rise of copper which has gone from $1.835 to $3.234 per pound in the last year.

More small diameter drill shafts are being sunk, so that there is communication down one, supplies down a second and a third, soon to be completed, will be for ventilation. The large drill that will drill the rescue shaft is now on site and is being set-up to start the hole.

For those who have not seen the layout, ( H/t Ericy this shows the relative position of the refuge and the slope that was the main access to the underground.


You will notice that there are a few more turns than the simple spiral that some of the networks have been showing.

Deepwater Oil Spill - Flushing and Fishing

BP has now responded to Admiral Allen’s request for more information, and has obtained permission to replace the BOP and stack on the top of the Deepwater well, before completing the drilling of the relief well. They are also preparing to recover (fish for) the drill pipe that was left in the original well.

The permission letter from the Admiral reads, in the relevant section:


As a result, BP have flushed the subsea equipment which included the following steps:

The work began Wednesday afternoon and the flushing procedure will involve the following steps:
• The Discoverer Enterprise will attach a drill string to the top of the existing sealing cap.
• The middle blind shears of the sealing cap will be opened.
• The Q-4000 will pump an ‘anti-freeze’ mixture down through the existing manifold and into the BOP’s choke and kill lines. The liquid used in the flushing will be completely contained and carried to the surface through the Enterprise drill string.
• Following the flushing, the sealing cap’s blind shear ram will be closed.
Following successful flushing of the subsea equipment, BP will conduct an ambient pressure test to reassure that the well is secure. The test will be conducted over a 48-hour period, which mimics twice the time estimated to remove the original BOP and replace it with the Transocean Development Driller II (DDII) BOP.

At the present time it appears that the well is in the 48-hour period where the well is being held at the same pressure as that of the surrounding seawater, to see if there is any gain or loss in fluid or pressure under that condition. If there is no change, then the hardware will be removed, and the replacement BOP installed. It should be evident that there will be some care needed to deal with the 3,000 ft of drill pipe that may be still attached to the lower end of the initial BOP.

This was addressed in his press conference on Thursday by Admiral Allen, who introduced a new step in the process. After the current pressure test is completed, BP have now been tasked with seeing if they can recover the drill string from the well, before the BOP is changed out.

Bear in mind that the actual condition of the drill string is in some question. As the Admiral noted:

If you will remember when we cut through the riser pipe before we moved the stub of the pipe and unbolted the flange, we were concerned there might be pipe or even two pieces of pipe there.


 
And one of our procedures we were prepared to do was actually put a metal band around both pieces of the pipe, pull them together so that the spooling tool could fit over the top (inaudible) that connection between the blow out preventer and the capping stack.



When we actually cut the pipe and got in, we found out there was only a single pipe there. That leads us to believe that the pipe is suspended by the shears that closed but did not cut the pipe and the deep water horizon blow out preventer. 
 
And so we're working under the assumption that there is pipe suspended, held in place by the blow out preventer. We don’t know how far down it goes and we don’t know whether or not it is connected to the 5,000 feet of cement that was put in during the top kill.

So after the ambient pressure test is done, it would inform us as to whether or not the BOP could be removed without hydrocarbons being emitted. 
 
The next thing will be to see if we can remove that pipe. That doesn't preclude us from removing the blow out preventer and putting another one on. It will just make it a little more complicated and BP will have to provide us a procedure on how they will do that.

This fishing expedition (which was also addressed in Kent Wells discussion, though that has not been released yet) is expected to occur immediately after the pressure test, i.e. sometime on Saturday.

The fishing recovery (so-called because you have to “fish around” to find the bit and engage it) will involve attaching a specifically designed fishing tool to the end of a length of drill pipe and seeing if this can get sufficient hold of the drill pipe so that it can be recovered, if the shear ram holding it in place is released. The Admiral suggested that this would be a drill bit

We are going to actually put a drill bit down in the blow out preventer and attempt to extract the drill pipe. The reason we want to try and extract the drill pipe that reduces the risk that when we remove the blow out preventer and put the new one on, there won't be an (off score) or some kind of a bar to having a seal with the new blow out preventer.

I anticipate that the tool used will be quite different from the conventional bit – some options that I found to illustrate the range:

Fishing tools (Logan Oil Tools )

Bear in mind that the tool has to grip the drill pipe and hold the weight of the string under the BOP after the shear is released. The tool will have to penetrate into the deformed metal of the pipe (remember the picture of the pipe and riser other side of the shear) and get a good enough grip that it will hold up to 3,000 ft of DP. So the grip has to be a strong one. It will be interesting to see what sort of tool BP suggests using.

Screen capture of the sheared section of the drill pipe and riser.


There are also ongoing tests to see if the contents of the annulus can be established, since it is still not clear whether this is oil (which would indicate that at one time there was communication through the bottom of the annulus with the reservoir, and thus a failure of the annular cement around the casing) or it could be mud (from the well contents before the initial cement was injected). That may not be known, with confidence, however, until after the BOP is exchanged, and the relief well intersects the bottom of the borehole, which is now not expected to occur until after Labor Day.

Deepwater Oil Spill - and this week's TWIP

Admiral Allen helped with the release of some of the rescued turtles from the Gulf today before giving his press conference at Cedar Key, in Florida. He noted that while there has not been any final decision yet on what to do best in moving closure of the Deepwater well forward, some steps in that process are happening.

For example, the Blowout Preventer (BOP) from Development Driller II (the second relief well) is going to be needed at some point to allow drill pipe to be inserted into the Deepwater well, so that a top cement plug can be inserted. To that end the BOP transfer is now being expedited. At the same time the Q4000 and the Discovery Enterprise are being brought back over the well, for several purposes. Initially these will be used to flush other fluids from the BOP, the production casing and any other accessible volume within the well. (Note that this will likely not include the fluid trapped in the annulus since there is no easy way to displace this). Once the volumes have been cleared the fluid used to sweep them will be replaced with seawater, emulating the condition when the BOP is removed. By monitoring the pressures in the well during this process, and with the necessary safety valves in place, this will assure the scientific panel, and the Admiral, that removing the BOP and stack won’t cause a problem. Hopefully by doing this, among other things, it will resolve the problem of the slow bleedoff in pressure that has been occurring within the stack during the current testing process, but which is blamed on the escape of trapped gas. They will then decide whether to install the new BOP before completing the relief well. Since, in other words, nothing much has changed, let me go on to look at the new “This Week in Petroleum” which came out today.

As the adverts on television and the newspapers will tell you, summer is coming to an end, and school sessions are about to restart. Which means that we are coming to the end of the summer driving period and, as a result, demand will, likely in a couple of weeks, start to decline. As the latest TWIP (This Week in Petroleum) notes, we aren’t quite there yet, and demand is running some 250,000 bd above last year , for gasoline, but we are close to the turnover.


The oil companies can see the event coming, however since it occurs every year, and so the refineries are lowering demand for the season.


Which, given that domestic production continues relatively constant (but up around 200,000 bd over last year, at 5.4 mbd) means that there is a slight decline in imports. Though it should be noted that these are still running about 0.75 mbd above last year.


At the same time ethanol (which I haven’t tracked before so am less sure of the seasonal trends) continues at about 0.85 mbd.


As the driving season ends, so the US moves into the time when oil, particularly in the NorthEast is used for heating. TWIP this week is looking at the changes that may happen in that region as the various State legislatures look at reducing sulfur content of the heating oil to bring it into line with the regulations governing highway diesel, which are a lot more restrictive on sulfur content. (Note that it is the sulfur content of oil that gives it the “sour” designation, and the world is moving away from easy, cheap supplies of the preferable “sweet” crude which has a low sulfur content.) . As the TWIP notes:

Initially, the change to ULSD for heating oil may limit import supply sources, as many parts of the world do not produce ultra low sulfur distillate fuels. During the winter (December through February), high sulfur distillate imports into the East Coast account for about 20 percent of this region’s total heating oil demand on average, and about 50 percent of distillate imports. Furthermore, during past cold snaps when supplies run short, high sulfur imports have provided most of the relief to the increased heating oil demand.

The transition will present other challenges. Some refineries supplying the Northeast with heating oil will need to make investments to produce ultra low sulfur distillate fuel for this market. Terminal transitions to low sulfur heating oil will need to be made, as well as changes to supplies of low sulfur additives or blending components to create winter-blend heating oil.

Given that the world's supply is increasingly sour this will only make the problem worse, and will further mandate changes in refineries to cope with the change in demand, without which a bottleneck may develop within the system of supply.

Deepwater Oil Spill - how to deal with a dead well?

The Admiral confirmed, in his Friday press conference, that the negative pressure test on the Deepwater well held steady for 24-hours without any inflow of fluid into the well, or increase in pressure. That means that there is sufficient cement in the annulus to block a free passage from the reservoir, through the annulus, to the well head. In other words the well is killed. The problem now becomes something different.

As I mentioned yesterday the central section of the well, inside the production casing, is full of cement. The only path possibly available is up the annulus, above the bottom section where cement has filled it. The problem that is now faced is that no-one knows how much of the cement in the annulus was there from the original cementing of the production casing into place, and how much from the injection of cement during the static kill. If it is a relatively small amount, then there is a risk that this barrier may fail, with time, and oil under reservoir pressure can then flow up the annulus to the well head. And to help with the discussion, here is the picture that I have used before to illustrate the situation.



I would suspect that it is a relatively thick barrier – the original injection of cement into the well from the production casing was, if my memory serves, about half that required to fill the annulus to the previous cement lining injection. Given that this is 800 ft above the bottom of the well, then there is 400 ft of cement above the shoe in the annulus.

In a relatively close to surface operation, the flow of fluid across the bottom of that column might induce enough cavitation to eat back the cement by about 20-ft or more (Glen Canyon Dam, and Tarbela High Dam for eg) but with the back pressures in the well that would suppress cavitation, I don’t anticipate that there was that much erosion out of the flow path of the oil and gas to the bottom of the well. There could be enough erosion along the contact with the overlying sandstone, which would erode out the column over the height of the sandstone, (say 60 ft) but even with that there is likely at least a couple of hundred feet of cement in the annulus above the reservoir creating a seal.

But that leaves the problem of the up to 1,000 barrels of oil that may be trapped in the annulus, begging the question as to how it is supposed to have got there if the cement in the annulus retained its integrity above the reservoir.

To determine if that is oil, which would imply that the above supposition was wrong and that the well had no cement integrity in the annulus until the cement from the static kill provided some, the relief well has to intersect the original well. When it does so it raises two problems, only one of which I mentioned in the last post.

The one I mentioned is that with a cement plug in the annulus below the intersection if BP start to inject fluid into the annulus they don’t have an easy way of displacing the fluid already there. There is nowhere to push it, and no clear way to circulate it out with the relief well configuration. The logical path to push it upwards out of the well runs into a slight problem that the Admiral introduced today, which is that the part between the new stack and the old BOP (the spooling tool) is only rated to 7,500 psi. And there is no simple path for fluid to flow from the annulus up through the existing hardware on top of the rig into a pipe that could carry it to a vessel at the surface.

The one that I did not mention was that if the original cement has been removed over the full column of the annulus down at the bottom of the well, and only replaced by the cement injected during the static kill, then there is no way of knowing how thick that barrier is. Raising the pressure in the annulus to inject cement into it from the relief well could break that barrier (though it would also provide a path for oil in the well to displace downwards back into the reservoir and thus dispose of maybe 10% of the oil in the annulus., which still leaves the question as to how to displace the rest.

On the other hand if the relief well goes into the annulus and finds nothing but mud (from the pre-cement days when the production casing was installed) then the question becomes moot.
.

Deepwater Oil Spill - time is not our friend

There is a certain frustration in hearing some of the officials who act as spokesmen for the management team handling the spill from the Deepwater well in the Gulf of Mexico. Their evaluation of the situation is bound around a full collection and compilation of the existing evidence, a comprehensive and contemplative understanding through a scientific explanation of the causes of whatever anomalies and other behavior that is not following the model anticipated, and subsequently then working out the best steps forward and determining the potential benefits relative to alternative approaches. Such an attitude works well in a scientific laboratory, where whether the results are available tomorrow or next week only really matters if there is another lab in the world that is working closely along the same lines as you are. (And if the work is relatively topical that is often the case). Unfortunately this relatively leisurely approach to making progress is not nearly as compatible with a situation where a high-pressure piece of equipment is showing signs of leakage, and where there is the possibility that, within the week, equipment is going to have to be withdrawn from the site because of the imminence of a hurricane.

The imposition of an ultimately superior layer or more (depending on how much the White House is actually involved in decision making) of evaluation and decision making can do little beyond stretching the time over which decisions are made, eating up the time that is available for action, before the current gentle weather window closes. Now it may be that the current tropical depression will not solidify into a problem (I’ll let wiser heads in those topics answer that question), but even if this one does not, there will come a time when one will, and the working interval is shrinking.


Some of the worries about seeps in the vicinity have now been put to rest, in his brief yesterday Admiral Allen noted:

The first one was to see pitch about three nautical miles (Ed. Note amended to kilometers) from the wellhead itself. We do not believe that is associated with this particular well integrity test or the Macando well.

Similarly the bubbling from the sediments around the well have not been seen as something to worry about, although the material ejected is being tested. (It proves very difficult to get a meaningful picture of this). There is, however, one leak that is due to the well, and that is in the equipment that is sitting on the well itself.

Let me just tell you right away, because this happened overnight, as you know, we had a – a connector piece of equipment that we established in to allow us to put the capping stack on. These are the three rams that are associated with the capping stack. This is a schematic of those three rams. The leakage is occurring in a flange just located right about here, and there is hydrate formation appearing on this side of the capping stack as we move forward.

We do not know, but we do not believe this is consequential at this time, nor is – doesn't appear that the hydrate formation is inhibiting any operation of the capping stack. This is something we will continue to monitor as we move forward.

He noted that

it is the collective opinion of the folks that are talking about this that the – the small seepages we are finding right now do not present, at least at this point, any indication that there is a threat to the wellbore. . . . . . . There is a – there's actually a metal gasket in the flange, rather than a rubber (one). It's actually a metal – metal seal in there. And that appears to be the source of (the leak). But we don't know if it's consequential to the operations of it. It's not a huge leak, but it is causing the formation of hydrates.

(Ed note I corrected some transcription errors). The lack of concern seems to focus on the possible stratification of the fluid in the wellbore, and the concentration of any sand, which could cause problems if rapidly released.

Now that in itself is somewhat revealing, since one of the things that I have discussed in the past is the concentration of sand in the fluid flow, and that, when the fluid gets to a pressure differential of 2,500 psi or more that sand will erode metal and anything else in its way, as it flows out. With the sensible admission of the presence of that sand, what BP intend, apparently and if necessary, is to bleed the pressure down sufficiently slowly that the current segregation within the well, with the lighter gas-related hydrocarbons rising to the top, can be maintained until the pressure differential is low enough that the sand would no longer cause much erosion if caught up in the fluid. (Whether this would need to take the “several days” that Admiral Allen suggests is, perhaps, debatable.

There are a couple of problems with that. The first is that the sand is not in a single size range, but likely goes all the way down to sub-micron in size. The smaller particles don’t settle out that easily and thus are likely to be present to some concentration in the fluid throughout the well. Which raises the second problem which is that particles do cause erosion if they are moving over a surface at relatively high speed (caused by the pressure differential). In a much earlier post I discussed this and the effects that it might cause.

In my other life we have dealt with the problems of having abrasive get into high pressure fittings, and the leaks that result. Leaks tend not to fix themselves, and get bigger over time. Expecting that they might not change over the next month, while the odd hurricane might pass by, and the relief well completion gets postponed, is not a reassuring path to take.

In Kent Wells review on Tuesday he was, similarly to Admiral Allen, complacent about the leaks.

And then in terms of the couple of gas leaks that you probably observed on the BLP and capping stack. Those are just coming from places where we have what we call (metal) seals. Those are small leaks that are as a result of gas. Those connections have been tested to very high pressures in the case of the capping stack we actually tested it to 15,000 PSI with water and with no leaks, and it’s just when we – we probably got a gas bubble that’s formed up there and that’s why we have that very slow leak. It’s nothing that we’re concerned about.

At those pressures and temperatures, the gas is still liquid and still capable of carrying sand with it.

The potential for injecting mud to kill the well, which is getting more of a hearing at the moment, could be the way forward. Once mud in any significant volume is introduced into the well, through existing lines initially designed just to do this very thing, then the pressure at the top of the well will decline. This lowers the differential pressure across any leaks, lowering the flow and extending the time period before they may fail.

But, in regard to doing this “top kill”, Admiral Allen noted

We now have a closed system, so there's back pressure. And so the question is is there enough back pressure there where you could do basically more of a static rather than a dynamic top kill, where you could put mud in. That might suppress the hydrocarbons.

There's been some discussion about whether or not that might be possible. We're looking for BP to give us an idea of whether or not that it's possible, how they would do it. And we'll react to that when we receive it.

And BP themselves does not have a sense of urgency about moving forward with the process. From Kent Wells:

And then in terms of the static kill – and once again, I want to reinforce, no decisions have been made yet on proceeding forward with that. But we are continuing with preparation and planning. We continue to get equipment lined out, what we would want to do, making sure that we will have the right equipment out there to do it, writing procedures, starting to get procedures approved.

At the same time, we’re doing testes (sic) with scientists, challenging the way we’re thinking about this, what we’re doing, so we’ve got parallel paths going on that’s leading towards somewhere ideally in the next day or two that we’d be in position through unified command to make a decision whether we’d go forward with that.

He may take a couple of days to make an animation showing how it will work. Essentially however it involves reversing the flow down one of the kill lines (originally set up to allow mud flow into the well) which are now being used to allow oil to flow out of the well and up to a service vessel. From Kent Wells:

Now, one of the things we do need to do is we need to make some changes on the Q4000 to change it from its ability to contain oil and turn it back around into the pumping facility. But that does not take us very long to make that change and of course we’ll always have the ability to change back if at some point we need to do that.

It will, likely, take much longer for management to decide whether or not it should proceed. And the weather window continues to shrink.


Oh, and from the Admiral’s brief, in case you missed it.

The Discoverer Enterprise is no longer on station.