Deepwater Oil Spill - Waiting for the cement to set

BP began pumping cement into the Deepwater well at 9:15 am CDT on Thursday and stopped the operation at 14:15 CDT, having thereby pumped cement into the well for a period of 5 hours. The intent was to fill the well and any wormholes and voids that had developed in the reservoir during the leak. The cement has to harden before it can be tested to insure that it has integrity.

During the process Admiral Allen held his press conference and commented that the wait for the cement to harden would likely be in the 24 – 36 hour time frame, after which the relief well will start to drill forward into the annulus. The process of going down, intersecting and then cementing the annulus, and then doing the same for the production casing is apparently further confirmation that the well flowed up the production casing, which implies a shoe failure, rather than the annular failure which was the predominant theory of failure earlier in the summer.
Note the Admiral’s comment on where the mud and cement from the static kill went.

Absent of what we've done in top kill, the assumption is you would have to go in, pump mud and cement into the annulus. But that hardens. So you've got that locked down. And you will come in and drill again into the casing.

Once we get in there we will know how much of an effect we've had with the mud and the cement from the top. That could shorten and make more simpler the bottom kill. That was one of the reasons to do it, and also reduce the risk of the bottom kill. Exactly.

However, the final confirmation will not come until the relief well finalizes the kill, which is still the plan.

I have stated over and over again, let me be perfectly clear. I am the National Incident Commander. I issue the orders. This will not be done until we complete the bottom kill.

With the well cemented shut, once the pressure tests are carried out to validate the seal will hold, then the well can be considered effectively sealed, even though it is going to take another two weeks (one week to intersect, check and cement the annulus, then another week to do the same for the production casing) before the fleet of ships can disperse, leaving the well itself to history.

At the same time the fleet of ships that has been capturing the spill will move closer to shore, as the last of the oil that flowed into the Gulf is likely to be more evident now at some distance from the well.

The latest distribution of how the oil has fared is shown in this pie chart:


There will continue to be a lot of controversy over these numbers. Some of them are based on actual measurement, some on models, and the residual is a catch-all covering the difference between the estimated flow and the volumes in the other slices of the pie. I would still like to see the inside of the BOP, presuming that it will at some time come to the surface, to see how much erosion went on, and thus whether there was a build in the flow rate or, as has been suggested by the Admiral, a higher earlier peak in the flow.

It is welcome news that the well can now, if necessary, be left without any further risk of oil leakage into the Gulf. Given that the possible storms are multiplying, and that we are moving into the more intense period for hurricanes, the relief felt by most at having reached this stage (assuming that the cement proves out, or is – if necessary – re-injected with a finer grade to ensure a seal if not) must be tangible.

Potential storms and Colin (NHC)

It will also allow me to start looking again at some of the other concerns that are developing around the world that are of concern as we stare into the tea leaves predicting the available fuels for our energy future.

Deepwater Oil Spill - Cementing the well

The Deepwater well has now reached a point where the mud inside the well is applying enough weight to the fluid in the formation that the flow of fluid, when such exists, is now from the well back into the rock. The well is sufficiently secure that, just before 7 pm CST Admiral Allen issued the following press release:

Based on the successful completion of the static kill procedure and a positive evaluation of the test results, I have authorized BP to cement its damaged well. I made it clear that implementation of this procedure shall in no way delay the completion of the relief well.

In his press conference today Kent Wells described the steps to kill the well, and what is currently happening as the work moves toward sealing the well.

The crew is now running the drill pipe within the relief well, but must first run a test of the Blow-out Preventer (BOP). There is a regulation, which the other drilling rig did not follow earlier in the process, that is, no doubt, now being practiced.

The Transocean Development Driller II (DD II) working for BP, received one INC (Incidence of Non-Compliance) because it had not alternated between control stations for BOP testing. MMS regulations require that the regular 14-day BOP tests alternate between the BOP station on the rig floor and the remote station located at another site on the rig. On the DD II they conducted the BOP pressure testing only from the driller’s control station for the last two tests. They did perform function testing on the remote station, but the pressure testing was only performed using the driller’s station. MMS has ordered the rig to alternate control stations in the future. . . . . . in addition, as a condition of its drilling permit, the rig will be required to conduct increased testing of the BOP stack and Remote Operated Vehicle (ROV) intervention both on the rig and on the seabed.

I presume that it is this scheduled BOP test that is currently being planned. After it is over then the excess cement that is still in the casing will be drilled out. This will allow instruments to then move over the full length of the injected cement to ensure that the cement was placed properly (using a cement bond log – something that was controversially not done by Schlumberger before the well failure of the Deepwater Horizon). In addition there will be a leakoff test, to test the strength of the surrounding rock.

Simplistically the pressure in the bottom of the well is slowly increased until the fluid in the well starts to penetrate the rock, shown when the pressure no longer steadily increases as fluid is added. This is then used to determine the weight of the mud that will then be used to drill the last section of the well (to ensure that the well pressure isn’t high enough to reach that pressure that will fracture the rock, and lose fluid to the formation).

With that in hand the well will start the short advances, then be surveyed, then advance again, to ensure that the relief well remains on target to hit the original well, first along the annulus, and then to penetrate through the production casing to allow a cement seal of the whole bottom section of the well.

The static kill was carried out with a flow rate of 5 bpm, and Kent Wells noted the success that was achieved.

We were able to watch the pressure continuously and (see it) gradually decline. We were able to watch as the – if you remember, I mentioned the word we injected for the injectivity test, base oil. We were able to watch as the base oil and then the mud actually hit the reservoir. We were able to see (the well) pressure up, and then we were able to see that pressure come back down.

And these were all very encouraging signs. And then what we kept doing is we kept injecting it as five barrels a minute, injecting more of the oil that was in the casing and actually mud, and continued to inject it into the reservoir for a period of time to try to get – make sure we'd cleaned out all of the oil that we could out of the casing.

And so we pumped for a number of hours. And then as we got confident that we'd actually got the well into a static condition, we actually increased the rate up to 10 barrels a minute, and then ultimately 15 barrels a minute, and we did that to give ourselves confidence that, if we chose to go ahead with the cementing procedure, that we could actually pump at higher rates, because that will give us a more effective cement job. And so that went well, as well.

So we spent some extra time yesterday pumping more fluid in, just to give ourselves more information and confidence. So by the end of the whole process, we had injected about 2,300 barrels of mud, and a lot of that was actually designed at just cleaning out the casing and making sure that we could move forward with the cement job with confidence, if we choose to do so.

In earlier posts I had worried that injecting cement after the static kill could cause problems, because the mud might require higher pressures before it would flow into the formation, and this could cause the well to fracture (see the leakoff test comment above). However BP had designed the mud so that it would flow into the rock, as they have demonstrated, and thus would be displaced by any cement that was injected into the well to seal it, as the Admiral has now authorized.

The cap itself can’t be removed, since the pressure balance is achieved at sea level, not at the sea bed, and the system is being maintained, with small injections of more mud (75 barrels at 5 bpm every 6 hours) to keep the fluids mobile and stop any settling.

Again the injection of cement is likely to be an ongoing event as I write this post – so we will see what the morning brings. If they do run the cement, it is likely, as Kent Wells noted, that after the injection they will run a positive pressure test to see if the seal holds against higher pressures (without letting mud flow into the well), and then perhaps they will run a negative pressure test to see if, as they drop pressure above the cement, any fluid from below the cement makes its way through the cement and up the well.

Deepwater Oil Spill - tests end and the kill begins

Overnight there was a second set of leaks detected in the BOP assembly sitting on top of the Deepwater well in the Gulf, however these were successfully stopped by Tuesday morning and the flow testing of the well began. Oil was pumped into the well at several different rates, starting at 1 barrel/minute and ending at 7 bpm. During this series of tests the pressure in the well was monitored, and the results were sufficiently satisfying – “Textbook”, as Kent Wells noted, that the well is now in process of being killed as mud is fed into the well at a slow, but steady rate.

Admiral Allen described the plan, before the testing began on Tuesday morning. Somewhere at the bottom of the well oil has been flowing into the well, and before it was capped, out into the Gulf. To fill the well with mud, the oil that is in the well has to be pushed back through the flow passage into the rock it came from. There are some different flow dynamics involved in the flow back down the well, but given that the well has been flowing at rates of more than 20 barrels a minute, there was little reason to doubt that the flow could be reversed, as it was.

Increasing the flow up to 7 bpm allowed the engineers to monitor the increase in pressure that was required as the flow rate increased. The increase comes both from the higher resistance to flow as the oil moves down the tubular passageways to the bottom of the well, and in the increased resistance as the oil/natural gas Is forced back into the narrower passages in the rock itself.

UPDATE: Early on Wednesday BP issued a press release, announcing that the well has reached a static balance. In other words the weight of the mud injected has countered the pressure of the oil in the reservoir rock, so that there is no longer a pressure differential driving oil into the well. The process took 8 hours - less than was expected.


The equipment has been fitted with pressure transducers to measure the pressure at different points along the flow (though none beyond the BOP at the top of the casing). Admiral Allen described how this occurs.

We have three different sites where we're going to be taking pressure readings. And those pressure readings will be transferred every 12 to 15 seconds by wireless modem to their ROVs that are down there. And they'll be transmitted up into the control room here in Houston and be monitored continuously.

In addition we have what we would call an analog or a traditional dial-type pressure meter. And an LED readout that the ROVs will actually have a camera on and be looking at. So there are potentially five different pressure gages we will be reading to monitor the pressure.

This tells us a couple of things. It tells us the capacity of the system to absorb a volume of oil or mud. It tells how much pressure we are exerting when that volume goes in. We've established a maximum pressure inside the capping stack of 8,000 PSI. That will guide how much pressure is being used to push that mud in. Excuse me, the base oil.

And in the conclusion of several hours of doing that we will have a profile of how the mud will flow, how the well will react to the volume, and what kind of pressures we can expect to be generated. And then there will be curves established for if – we're filling the mud just into the casing, or the casing in the annulus. How we can expect how much mud will needed because there is more of this wider diameter, and the type of pressures we can expect based on that diameter and that volume. And then we will track the actual mud as it goes in during the static kill against those pressure versus volume lines. (Edited to note that the instrument is a Light Emitting Diode (LED) display and that the vehicles are Remotely Operated Vehicles (ROV) and not as transcribed).

The tests were successful, and Kent Wells reported on the success of the oil injection at 3:30 pm. BP also put out a press release, noting that they were beginning to inject mud into the well.

Based on the results of the injectivity test, BP started pumping drilling mud today at 21:00 (UK) and 15:00 (CDT) as part of the static kill operations. All operations are being carried out with the guidance and approval of the National Incident Commander.

The aim of these procedures is to assist with the strategy to kill and isolate the well, and will complement the upcoming relief well operation.

At this start of the injection it is not clear which paths the mud will flow down the well, but as Admiral Allen noted, by the time that 200 – 300 barrels have been injected, then the changing pressure in the well will tell where that mud is going. As I noted yesterday, the reason for this is in two parts. Firstly the oil flow has established a flow path from the reservoir up to the BOP, and outside of that flow channels where the oil is not flowing will remain full of oil, but largely unable to accept the mud as it is injected into the well (because fluid can’t be injected into a passage if there is no way for the fluid already there to escape). So the mud will push the oil back down the flow channel. But at the start of the process no-one knows if that channel included flow down through the production casing, flow down through the annulus around the production casing, or both.

Section through the well showing with the light yellow color the channels that the oil might flow through up the well, and which will be filled with mud.

Had the well integrity remained as it was planned, there would only be oil (the light yellow) in the center of the production casing after the well was brought into production by firing small shaped charges through the cement at the bottom of the well. There should be no oil in the outer annulus between the production casing and the rock. Obviously oil has been flowing up one or the other, or both, but no-one is sure which is the case.

However when the mud is added, then it will only flow down the well back along the path that the oil was taking. This will thus help tell which channel is being filled with mud. As a given amount of mud is introduced, then the weight of the column of mud will lower the pressure at the top of the well necessary to keep injecting the mud. (Which is sensibly the pressure in the reservoir less the weight of the section of the column which is oil and that which is mud). For a given volume of mud injected, knowing the length of the mud column from the change in the pressure value at the top of the well, it is relatively easy, knowing the cross sectional areas of the three options, to establish which of the channels the mud is flowing down through.

The mud is being injected relatively slowly, at about 2 bpm, but the channels are not that large so that within a few hours (in fact they should already know before I post this piece) they will know which path the oil is flowing through, and therefore where the leak at the bottom of the well is likely located. This will then help in the planning of the relief well. For although the injection of the mud should kill the well, so that there will be no flow into the Gulf, it will only be when then bottom of the well (and ultimately the top) are sealed with cement plugs that the well will be considered dead. Admiral Allen wants that to be clearly understood.

The Static Kill will increase the probability that the relief well will work. But the whole thing will not be done until the relief well is completed. The Static Kill is not the end all be all. It is a diagnostic test that will tell us a lot about the integrity of the casing. And the wellbore will tell us about the tolerance for volume and pressure. But in the long run, drilling into the annulus and into the casing pipe from below, filling that with mud and then filling that with cement is the only solution to the end of this.

And there should be no ambiguity about that. I'm the National Incident Commander, and that's the way this will end. It will be end with the relief wells being drilled, and the annulus and the casing being filled with mud and cement being poured.

And that, Hurricane Colin and other tropical depressions behaving, should be in the next couple of weeks.

Deepwater Oil Spill - start of the static kill

Progress on the relief well at the Deepwater Horizon well has now reached the point that BP have started the procedures for the top static kill of the well. There was a little delay in the installation of the casing for the relief well because, during the time that the well had been left untended during the last storm, the sides sloughed a little, and about 40 ft of debris accumulated in the bottom of the well. This was obviously more than had been expected, since the clearing run to remove this and condition the well took longer than originally planned. However that clean-up operation is now complete and the next step in the process, the initial flow testing of the original, now sealed, well to see how it behaves as fluid is injected, is now starting.

I am going to review some of the comments made both by Admiral Allen, and earlier by Kent Wells about the procedures that are now starting. I will also try and expand a little on the determination of what is happening as the oil, and then mud, are injected into the well.

Vessels located around the three wells in the Gulf (BP)


There are still a significant number of vessels around the wellheads of the three wells out in the Gulf. However the ones that are critical for the next phase of the operation are the Hos Centerline, the Blue Dolphin and the Q4000. However, in the best of circumstances the Hos won’t be needed, since it is largely there to provide a large quantity of mud, if necessary. The hope, however, is that it will not be needed.

It should take less than 2,000 barrels of mud to fill the well, and the Blue Dolphin has more than 8,000 barrels on board, so the Hos is more in the nature of insurance. Not, however, that the first stage of the process will use mud, instead it will inject oil back into the well.

To prepare for this, as Admiral Allen noted:

we had to remove all the gas out of the Q4000 riser pipe. We had to pressure-test the Horizon blowout preventer, critical in this process. We had to rig down the Q4000 production line to bring the hydrocarbons up and actually rig up for pumping operations that would allow us to put both oil and pumping mud back down.

Part of that involved making sure the yellow pod controls, which control the valves on the subsea portion of this work, that all the valves and the flanges have been tested to proper pressure ranges and that the pressure gauges that we're going to be looking at, they're going to be very, very important as we move forward, are all tested, calibrated and operating properly, and to make sure that we have backup and duality of measuring pressure.

There was a small leak in one valve, that had to be corrected on Monday, and the process is ready for the first phase of the test.

Both phases will feed fluid into the well through the kill line on the BOP, it is one of the purposes that the line serves in a conventional well. The fluid will initially be oil, and will be pumped very slowly (a barrel a minute) into the well. At this point, since the well has shown itself to be in good shape, apart from where the oil has been leaking into the well, the test has a simple goal.

Fluid flow path to the well (BP)

If the only exit from the well that is now open is the rock through which oil and gas were flowing into the well before the well was capped, then injecting oil into the well at the top, should force an equivalent volume of oil at the bottom of the well back into the rock.

The first test will therefore first find out if oil can be pushed back into the rock. By starting at a relatively slow flow rate the flow should start with very little additional pressure applied to the well (the science team have put a cap of 8,000 psi on the pressure that will be allowed in the well). After running for a short while at the slowest flow rate, the rate will be increased first to two barrels a minute and then to three.

The result should show that with little change in pressure, that the oil added is causing an equivalent outflow at the bottom of the well, and should (by looking at the pressure required for the flow rate) help determine how fast the well can be filled with mud (since the oil it is displacing has to flow back into the rock). The well flow will be kept slow for several reasons. One is that higher flows require higher pressures, and there is the bound that has been set; the second is that higher flow rates down the well will generate some frictional force that the fluid will also have to overcome as it moves down the well. Too high a value for the friction – which is additive to the driving pressure – and the well starts to approach the limiting pressure allowed for the exercise.

There is a third objective to the tests, but it is one that will be probably easier determined when the fluid is changed to mud. If the well had been completed properly then its structure would have an outside liner made up of a steel casing surrounded by cement, then there is a gap or annulus, then there is a central steel tube, known as the production casing, that is supposedly cemented firmly in place at the bottom of the well. The well has a leak at the bottom which is feeding oil either into the annulus, into the production casing or both.

By adding fluid at the top of the well, and seeing how the pressure changes as larger volumes of fluid are added, particularly with the mud injection, the changing pressure should show which column(s) are taking the mud, because the oil is flowing out of them back into the rock at the bottom of the well, and which are not.

As the mud injection continues the change in pressure (since the mud exerts weight on the bottom of the well it will lower the pressure needed for injection at the top) with inflow should tell the monitoring engineers, for the amount of mud injected, how long (roughly) the mud column is in the well. Knowing the relative cross-sectional areas of the annulus and the production casing, and the volume injected, this will allow the engineers to then know down which column the mud is displacing oil back into the formation. And since it can only do this if there is the leak at the bottom (since the cement should have sealed both), this information will be very helpful in telling those running the relief well what to expect when that well runs into the original one.

As the Admiral noted

What there should be is a slow pressure decline, and that would tell them that they're slowing overcoming the pressure of the hydrocarbons with the weight of the mud moving forward. That decline will be less with the amount of volume if it's in the entire annulus, so about five or six hours into this, the pressure readings are going to be very, very significant on whether they know they're filling the pipe, the casing, or the annulus moving forward.

At that point, once they have ascertained exactly what it is they're doing, they will finish putting the mud in. The fourth step, if it is decided, would be whether or not to put cement in. That would be done based on the results of the test and whether or not the mud is required to fill both – fill the drill pipe, the casing and the annulus.

Given that the evidence from the experience with the relief well is that the sides of the wells can slough into the well and that the annulus that the relief well is drilling into was left partially open so that it could have sloughed down onto the original cement, making it difficult to possibly ensure a good seal in that area, I am not sure that the cement injection would work well from the top, and might be better left to the relief well.

Fortunately the next major storm may go East of Florida, rather than into the Gulf, which may give more time for the RW to reach and do the final kill, but time is still not a friend in these operations. But the time required for the next phase should be relatively short. Again quoting the Admiral

They think it's going to take about four hours to evaluate the data from the injectivity test, in other words, to understand exactly what the pressure means, what the pump rates are, and what the maximum pressure that was measured in the capping stack.

It could be less, but they're assuming four hours. And then they're looking at about another five hours to do the initial pumping, start pumping mud in at two barrels per minute. That will start getting them to a threshold where they should be able to start – they have these curves on whether or not it's the annulus and the casing or just the annulus or just the casing and how the pressure should perform and decline.

So as they pump those two barrels per minute in over the next first five or six hours, they're going to try and discriminate exactly which pressure line they're on that would tell them they've got an issue with the annulus or the casing or both. That entire period will take about five hours, so you're four plus five.

Then, depending on – once they understand that, whether you have to fill the entire casing and the annulus (up and it splits), it could either be on the low side, take you about 33 hours to complete it, or as much as 61, if they have to pump enough mud and it would fill both the casing and the annulus. It kind of diverges at that point.

The next 24-hours should therefore be very productive, especially since BP has promised to keep us informed of the progress. Once the initial results are in, it is then intended to keep adding mud until the pressure at the top of the well falls to zero, meaning that the driving pressure of the reservoir has been balanced by the weight of the overlying mud. That will be the operation that will take the 33 to 61 hours.

Deepwater Oil Spill - Restarting Progress

BP does not seem to have gone back to the daily briefings, let alone the twice-a-day ones that were being issued just a couple of weeks ago. Admiral Allen has given permission for the top and bottom kill (through the relief well) activities to continue. The Admiral also noted that the riser for the RW has been reattached, and the reconnection, removal of the plugging packer, and cleaning of the well is in process. It is estimated that the intersection with the original well will now occur on the 7th August, with the final set of casing being run into the hole this week, and then, after cement injection, the well will WOC (wait on cement) while the cement hardens, and is then checked. In the meanwhile the undersea valve system is being modified to carry out the static kill that I discussed earlier. (And the leak monitoring has transferred to the BOA ROV 2, which is now showing four leaks.)

Once the flow channel to the well is restored, and the casing set and cemented in the relief well, then the Q4000 will carry mud from the HOS Centerline, driven by pumps on the Blue Dolphin into the riser, and down to the BOP to carry out the static kill. The Admiral currently expects that this will begin on August 2nd. He did note that the plan is still to inject cement into the top of the well, after the mud has killed any pressure differential between the bottom of the well and the reservoir, and thus also stabilized the well.


As the more immediate and visible problems reduce, with this path toward the final sealing of the well, and with future flows from it into the Gulf becoming less likely, the oil on the surface, and that migrating towards the shore is getting less. This will allow the Admiral to redeploy assets. For example it now appears that the risk of oil East of the Mississipi is declining, and that commercial fishing there may reopen before the end of the week, given that

"We're 90 days into this, and I think the data speaks for itself," said Randy Pausina, assistant secretary for fisheries at the Department of Wildlife and Fisheries. "There's been no indication that any seafood is even remotely close to being at any level of concern. Find me the concern and prove it to me."

Sport fishing has already been restarted.

We are now in the most intense driving season of the year, and this is evident, with traffic noticeably heavier on the roads in New England in recent days. SeaCoast Sunday noted in their paper edition on Sunday that occupancy rates in the York area of Southern Maine are over 90% during the week and at 100% on weekends. It is therefore not surprising that gas prices are on the rise, being on average 25 cents higher than this time last year.

We have been fortunate that the weather in the Gulf has not generated that much damage to the rigs and platforms yet this year, and those that were affected by Bonnie are now back in business. But the season is still young, and may yet remind us of our vulnerable dependence on oil.

Deepwater Oil Spill - After the storm

The “Bonnie” storm has passed, and the different vessels are not only returned to the site, but are already making progress in returning to operations. As Admiral Allen noted on Sunday

DDIII is now running the riser pipe down. They have 67 joints to complete, they've done 39 of those as of about 10:30 Central Daylight time this morning, need about five more hours to do that. They are planning to latch on to the well around midnight tonight. Development Driller II which was – had drill – was involved in drilling the backup well is returning to site and will start running their riser today.

Q4000 is inspecting the yellow pad, that is the control device that's placed subsea to operate the hydraulics. They replaced the valve on that and they plan to install it later on today and then they will begin preparations for the static kill operations.

He also noted that the pressure in the well has now risen to just over 6,900 psi, while the temperature at the BOP remains at 40 deg – suggesting no flow and that well integrity is apparent. The storm has, however, dispersed and moved the oil, and they are resurveying to find where the threats now lie.

He then gave the current anticipated time line for the kill of the well.

.

The time line is roughly over the next week. We'll return the Development Driller III, run the riser pipe, latch in, pull that undersea containment device, which they call a packer.

They're going to need to circulate conditioning fluids through that pipe line to make sure it's ready what they call conditioning a hole and then some time in the next week they'll be in a position to be able to run that (nine and seven-eighths inch) liner which is the critical path right now to moving – to move ahead.

Once that liner is laid, they're going to put cement in and around it. And at that point the two vessels that were supporting the liner operation, one call the Blue Dolphin, the other is called the Center Line will redeploy and hook up with the Q4000.

This is sometime – this will be sometime during the week of 1 August. And they will set up for that to be able to inject the static kill and during that week of August subject to the (inaudible) I'm sorry the containment pipe being installed and cemented in then we will go to the static kill with the Q4000.

Kent Wells has also now released the animation showing how the different kill methods will take place, and interestingly also showed the section at the bottom of the well that shows the different layers of oil bearing rock in the reservoir.

The animation follows along the process in much the way that I described in an earlier post on the bottom kill, which is now scheduled in two parts. As the Admiral noted, the first part is to case the relief well. Once that is in place, and the cement run, then the top kill will start.

Because the well is shut-in, the plan is that the flow to the surface will be reversed. the flow lines are now passing oil and gas to the surface, the circuits will be reversed to return them to their original condition, and then mud will be fed into the well. Because this can be done a little at a time, it will be, and the pressures will be monitored to ensure that, as the well fills with mud, that there are no integrity problems.

Once the well is full of mud, they may try pumping cement into the well from the top (this is shown in the animation), though, because of concerns over flow control, I would suspect that they will not put the cement in until they connect through the relief well, and they will then do a two stage (annulus and then inside the casing) final kill.

And I should note that, contrary to my concern, the leaks that are being shown again now by the HOV ROV1 are no worse than they were before the storm, so perhaps that is not going to be much of a problem going forward.

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.