Re: Deepwater Horizon oil spill disaster- Update on BP's attempt to stop the oil leaks
Re: Deepwater Horizon oil spill disaster- Update on BP's attempt to stop the oil leaks
DATE: August 02, 2010 17:12:51 CST
Transcript ? Press Briefing by National Incident Commander Admiral Thad Allen
Below is a transcript from today's teleconference press briefing by Admiral Thad Allen, National Incident Commander for the Deepwater Horizon/BP oil spill.
A downloadable audio file of the conference is available
here.
August 2, 2010
1:45 p.m. CT
Thad Allen: Obviously, the topic of the day are the tests leading to the static tests we're going to be doing on the well. I'd like to bring you up to speed on this. I'm going to go into a little bit more detail than I have in the past, because I know there's a lot of interest on exactly the sequence of events and what's going to transpire, and I'd be glad to take any questions when I'm done.
What we're actually involved here is a series of tests of which included is the ability to put mud into the well with the potential to reduce the pressure to zero, which will significantly reduce the risk of any discharge, and also, assist us in the ultimate bottom kill, which is the end result, but there are four basic steps to this, and I wanted to go through each one of them individually so you would know.
Over the last 24 to 36 hours, preparations have been made to do this. A lot of this involves what's going on with the Q4000. As you know, the Q4000 was being used to produce hydrocarbons out of the stack and at this point will be reversed and used to actually pump materials back down.
So to do that, 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.
To that extent, there are going to be three different ways we're going to measure pressure, different gauges on the blowout preventer and the riser, and the capping stack itself. One will be acoustics, where we will take pressure measurements, and they'll be transferred via wireless modem to an ROV and then transmitted to the surface. We will have analog pressure gauges, which we will look at, utilizing the cameras on the ROVs and then LED gauges, which we'll look at, too, so basically three different ways to measure pressure and pass that information back up to Houston.
All those preparations have been taking place over the last 24 hours, and we're to the point now where we are scheduled in some time in the next few hours to begin the injection test itself.
I was advised just before I came in that there is a small leak on a valve on the Q4000 they are repairing right now. That will probably take a couple of hours to repair, so we're looking approximately now of starting the injection test sometime later on this afternoon.
The injection test is designed to do three things ? number one, establish communication or a path for fluids to flow from the Q4000 down into the well itself; second, to establish pumping rates, and they will do that by taking basic oil and pumping it down at the rates that they would look to put the mud down and make sure all the lines and all the pathways can hold that pumping rate; and, finally, they will do pressure checks.
The science team, working with the BP engineers, have decided that as we go through this procedure, that the pressure in the capping stack itself should not exceed 8,000 pounds per square inch. There's a safety margin built into that.
So they will control, actually, the pressure on the wellhead ? or the pump head on the Q4000 to make sure that the pressure and the capping stack does not exceed 8,000 PSI.
Got the background noise there? Good, thanks.
So after the preparations and the injection tests are complete, the injection test findings will be evaluated. That will probably take several hours. And then they will initiate at that point what has been called the static kill.
The reason I'm differentiating all this out, the static kill is not a monolithic thing that will happen today. It is a potential of one part of the diagnostic tests that are being done. It is not an end in of itself.
And what they will do is they will start pumping mud at a very low rate.
This is mud that weighs about 13.2 pounds per gallon, and they will pump it in at, first of all, one barrel per minute, and then raising to two barrels per minute, and then they will slowly pump that into the blowout preventer through the choke line.
Now, the results of this are going to depend on where the oil's at, and there are three potential places where there can be oil. We have the drill pipe itself, and we're not sure of the condition or how far that runs down.
We have the casing, in which the drill pipe sits, and we have the annulus, which is the area outside the casing between that and the wellbore.
Depending on how much of that space they have to fill up will dictate how long it will take to do the static kill portion of the diagnostic test. If it is only the casing itself, it could be a relative short period of time. If they have to fill the drill pipe, the casing, and the annulus, it could take much longer, and the range to complete the entire operation could be anywhere from about 33 to 61 hours.
We should know earlier on, though, what the results are, and, of course, we'll be passing those to you as we find them out.
You may ask, why would we be filling the annulus with a top kill? Because
I keep saying we need to go in the bottom to fill the annulus in my prior briefings. There is a possibility ? and we don't know this ? that there could be a seal further down in the well that could have been compromised and allow the oil to come up through the annulus and be part of what's been sent to the surface through the blowout preventer. So they need to be prepared to not only put mud down the drill pipe and the casing, but they have to fill the annulus from the top, as well.
And, again, this will be dictated what they find. 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.
We have finished laying the casing run from Development Driller 3 for the relief well, and we are holding what we've got right now pending the results of this, because the diagnostics that we will learn regarding the pressure thresholds, the performance of the well with the mud going in will tell us a lot more about the casing and the annulus as it relates to what we need to do from the bottom up.
And as I said, once we decide to move forward, we will have about 100 more feet to drill on the relief well from Development Driller 3 offset by about four-and-a-half feet from the Macondo well right now, and that'll be at an inclination of 2.9 degrees before they intercept the annulus. They would then at that point proceed to pump mud in to fill the annulus and then drill into the casing, where they need to do that.
So if you can see, we're going from the top first to get the diagnostics, do as much as we can with the mud from the top, learn as much as we can to be able to be more successful, and completing the kill from the bottom when we do that, and I'd be glad to take any questions you may have.
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Read more:
http://www.deepwaterhorizonresponse.com/go/doc/2931/840439/
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