operations are ongoing it seems. the speculation from the oil drum is that bp is trying junk shots and mud injections then backing off to see how things worked out, which allows the oil to push the mud and other stuff back out again.
here's the commentary thread at the oil drum, which is still very good:
The Oil Drum | Deepwater Oil Spill - Deciphering The New Activity (Top Kill, Junk Shot, Etc.), Watching the Flows, and a Live Comment Thread
and this post from the comments to this thread written by someone whose screen name is rockman helped me feel like my grip on the top kill process is a little better
Quote:
Ran through all of yesterday’s post late last night. High marks for all including the newbies. I avoided TOD most of Friday…too much like watching paint dry as BP went thru the process. But at my daughter’s baseball game last night I had to offer a very non-technical explanation of the top kill effort and why it was such a difficult job. Perhaps too simplistic for many of the new smarty-pants here but it might be helpful to the newbies. Everyone feel free to judge.
Everyone knows what a water heater looks like. A little more detail: it’s a pressurized tank with an inlet line coming in from the water line to the house. To avoid tank rupture should pressures become excessive there is a “pop off” valve. At a certain pressure (let’s use 80 psi) it pops open and lets the water drain out. Now consider the BOP being the water tank. And our water tank has two pop off vales: one that pops at 80 psi (represents the pressure at the seafloor of around 2,300 psi) and the second that pops open at 400 psi (represents the 10,000 + psi of the wild flow). The objective of the exercise is to make the 400-psi valve pop open (this represents forcing the mud down the casing/drill pipe). So we start pumping in water to the tank (BOP) via the water line (choke line). At 80 psi the valve pops and water starts shooting out (the mud you see flowing out of the BOP/riser). We need to increase the tank pressure to 400 psi to make the second valve open (force the oil/NG back down the hole). So we have to increase the flow rate/pressure of the water line to force more water into the tank than the 80-psi valve is letting out. Of course, as we increase the pressure/inlet rate the water flows faster out of the 80-psi valve.
Obviously only one way to get that 400-psi valve to pop: inject water (drill mud) that much faster than it can leak out the low-pressure valve. Otherwise all the injected water (mud being pumped thru the choke line) will go out the low-pressure valve (BOP/riser). Now lets say we get the flow rate/pressure high enough to pop the 400-psi valve open. Yahoo…success! Sorry not yet. Did I forget to mention that not only did we need to pop that valve open but we need to keep it open long enough to fill up 200 water tanks (filling the csg with mud all the way to the bottom)? And what happens if we let the tank pressure drop? The 400-psi valve closes (the oil/NG forces what mud is in the csg to flow back out).
And there’s BP true dilemma: not only do they have to generate at least 10,000+ psi in the BOP they have to maintain it long enough to push the oil/NG back down 13,000’ of csg. I assume this is the purpose of the junk shot: diminish the leakage rate of the BOP.
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it seems that people are watching the feed and posting to this site as thing happen, trading information and interpretations. it's still the best source i've found for both.
apparently bp has stopped drilling one of the relief wells. this without particular explanation.
meanwhile, the rhetorical conflict over the clean-up, such as it is at this point, continues to happen much more quickly than does any actual cleaning up:
Gulf oil spill is public health risk, environmental scientists warn | Environment | The Guardian