Overview of Deepwater Horizon Blowout – Top Kill – Mud
Posted: May 24th, 2010 by: h2
This is just a rough overview of the current Deepwater Horizon blowout status. Don’t take any of these facts as quotable, though most are roughly correct, but if you need real sources, use real sources, don’t rely on a blog posting like this. I have made an effort to avoid the more common errors I’m seeing online currently, but some of these numbers are speculative at this point, nobody actually knows for a fact. But if you just want to get an idea of what’s going on now, today, this is basically the story. And you can also follow the ongoing TheOilDrum.com blowout thread.
Current Blowout Status
The 100k per day flow rates being tossed around on the internet are technically impossible, apparently the well, if totally open and free flowing, has something like a 60k per day maximum flow rate, but it’s not open, it’s partially restricted by the partially closed BOP valve, and then later on, by the crimps in the riser tube. From what I’m reading from oil engineers who have been posting on theoildrum.com, the most realistic flow rates of petroleum would be around 20k to 30k barrels per day, although it could be more in a worst case scenario. ROCKMAN and shelburn both seem comfortable with that range of estimate. A lot more than 5k reported, but it’s important to keep hyperbole on such events under control, especially when the numbers simply aren’t technically feasible. The stuff coming out is passing through what at least started out as a relatively small hole with something like 12k pounds per square inch pressure behind it, then that goes to the riser pipe,where it’s a bit more restricted by the bends. But the problem is that as the stuff comes out under that high pressure, it contains sand and grit, which expands the hole. That’s why the flow rates have increased consistently, and it’s what BP is actually worried about, the entire BOP / riser failing, and the unrestricted flow entering the gulf.
That’s why they are trying the top kill CNN, includes video animation of top kill method) stuff, but it’s also why it’s taking a long time, if it fails and ruptures the BOP unit, that would make the current spill look like child’s play, and there’d be no way to fix it until the relief wells hit. The mud will be pumped in at using 30k per square inch compressors, and since it’s denser than the oil, and because the BOP is partially closed (restricted flow, that is), the idea is the drilling mud will first rise to the BOP seal, fail to flow fast enough to pass it, being too thick, then go back down the well, since the compressors have greater force than the downhole pressure. If this works, whew. If not, worst case, the damaged bop unit blows out totally and we have unrestricted maximum flow rates for 2 months or more.
The top kill requires running pipes down to the ocean floor, hooking them up to massive compressors, capable of generating 30k pounds per square inch pumping pressures, then hooking those pipes up to 2 3″ inlets below the cutoff section of the BOP, then pumping in heavy drilling mud until it fills the down hole part of the well, thus blocking the upward flowing oil/gas mixture, after which the hole can be cemented shut. Difficult to do, and never done before at this depth.
New information (24 May 2010 18:39 GMT): top kill set for Wednesday BP says. This article has a lot of new information in it. Things are changing fast, hard to keep up.
If the top kill is not successful it could erode the riser and increase the flow from the well, Suttles said.
In case that happens, BP plans to immediately employ another cap on the well, a change from the plans Suttles announced Friday.
Friday Suttles said BP’s next option would be a junk shot, clogging the BOP with heavy fluids and debris like shredded tyres.
BP was attempting a top kill before a junk shot because a failed junk shot could cut off other well control options, Suttles said.
Now, the UK supermajor plans to cut off the riser from the lower marine riser package (LMRP) and attach another dome to collect the flow.
The “LMRP cap” would allow BP to capture as much of the flow from the well as possible while it works on other options to kill the well.
This is a fairly good summary of the sequence of events of the blowout, by shelburn.
The top kill using drilling mud is a method used on land fairly routinely apparently, and the logic behind it is quite solid, though of course it’s not tested at 5k feet water. Lots of unforeseen events surround this method, and BP themselves give it only a roughly 60% chance of success.”Suttles said he rated its chances of working at ‘six or seven’ on a scale in which 10 was certain success.”
We’d better hope that method works, because otherwise it’s going to take about 2 more months, give or take, at best, for the first relief well to intersect the main well pipe at about 18k feet. They have started a second relief well because sometimes it takes between 2 and 5 attempts before they can actually intersect the original hole. Quite an amazing feat if you think about it, drill down 13k feet starting at 5k down ocean floor and hit a target about 15″ wide. then change drill bits to a metal milling one to drill through the casing, all the while avoiding another catastrophic blowout.
The reason, by the way, they have to drill down almost to the resevoir depth is that the pressures down there are so high that if they intersect the well any higher up the pressure in the relief well won’t be high enough to contain the pressure in the original well bore. Which would result in an immediate and quite spectacular blowout in the relief well.
It took 10 months to stop the Ixtoc Gulf of Mexico failure, nobody hears about that one because it was 600 miles out to sea, and because it’s in a tropical area, the feared long term ecosystem destruction never happened because the little microbes, plus warm waters, shallower, ate most of the oil very quickly. Because that one was so far out in the Gulf, not too much oil hit the beaches, so it didn’t cause that much uproar.
The Australian Timor sea blowout, the Montara spill, took 5 relief well attempts before they could shut it down, in other words, the first 4 failed for one reason or another.
Why the US government should NOT take over the spill from BP
This is a common misconception, based on inadequate understanding of how oil spills are actually handled, that says the US should take over because BP is failing. But the way this works is that all oil companies pay into a pool, and that pool creates a single oil spill handling entity. If the US took over, all that would happen is that they would be telling the oil spill company what to do, but they’d also start taking the blame for failing to stop/clean up the blowout. It’s actually much better for BP to take the blame, since the groups cleaning it up and doing the deep sea work would be the same.
From what I gather, the only difference is that if the US government takes it over, they can basically order whatever they want, and hand BP the invoice, and BP can’t say or do a thing to avoid that. But given the enormity of this spill, and given the uncertainty of the top-kill actually working, you definitely don’t want to take authority, and thus implicitly, responsibility, for the spill until every other avenue has failed. In other words, until the top kill methods have failed.
Just imagine for example, if this was being handled by the Obama administration, what the rightwing talk radio nuts would be saying! They’d be blaming the failure to stop an unstoppable spill on the socialists in the White House. Given that reason / rationality is not in the neo-con/far right’s toolkit of methods, that’s another major reason to leave this spill squarely in BP’s lap.
How much oil is spilling out anyway?
Here’s a nice comment from shelburn on this question:
shelburn on May 24, 2010 – 5:43pm Permalink | Subthread | Parent | [Parent subthread ] Comments top
Estimates based on oil of the surface are very imprecise. You can probably download the USCG manual on oil spill estimation which talks about that quite a bit.
If someone says there is 25,000 bpd based on satellite photos I would interpret that to mean between 10,000 and 50,000 bpd. Then you take all the other factors that you can to modify that number.
We know from the underwater work and videos that the flow is over 5,000 bpd and most likely at least 10,000 bpd as a minimum. We know from the geology that the maximum well flow is probably about 50,000 to 60,000 bpd and that will be going down at some unknown rate. We know that there is a restriction or series of restrictions that is reducing the flow.
From all that it is probably pretty safe to say the leakage is over 10,000 and under 40,000 bpd. Anyone who tries to tell you that they can get an estimate that is better than about 40% plus or minus is either fooling themselves or trying to fool us. Unfortunately the media just grabs the highest number and reports it as if it was a fact.
That seems about right to me.