Cleaning up after elephants*, or more on EOR

So you're feeling cheap and don't feel like going to the sandwich shop, huh? So lets see what's in the refrigerator. An apple, some cheese, some butter – that will do. So you put them on the table and…. darn, you got a blob of butter on the apple. Rather than have it roll all over the table making a mess, you stick it under the tap.

With the water running on cold it seems to take forever to wash the butter off the apple, but if you turn the tap to hot, the butter runs off very quickly. The same sort of thing happens when you apply hot water or steam to the oil left on the sand grains of a rock after the primary and secondary recovery of the oil is over. The oil is a lot thicker than butter and you generally have to heat the water a bit hotter (it works best above 185deg F) but you can still clean the oil from the rock that way. There is, however, a bit of a snag. (And from this point on DO NOT TRY THIS AT HOME).

Think of it as little Johnnie (helped of course by Jessica) having raided the orchard and spread butter onto all the apples, gluing them together and filling the kitchen full, right to the ceiling. How do we clean the butter off and get it back without taking all the apples out and cleaning them one by one (which is sort of what they do with the oil sand up in Canada).

We could just stand in the hall and stick heaters up against the wall of apples, hoping that the heat would melt the butter and work its way back to the ones further into the kitchen. That sort of works, but burns the local apples and doesn't reach all that far. (They have tried setting fires inside oil wells). You could fill the kitchen with hot water, but while that washes out some of the butter, a lot of the heat goes into the apples and the water is cold before it reaches the back of the room. And the water doesn't have that much pressure to push the remaining butter off the apples. (In oil wells this is the secondary recovery that might get us back another 10 – 20% of the oil, except that they use cold water and some rocks have clays that swell when wet and this stops the oil from flowing).

What we need is something that will get through the gaps between the apples and keep its heat. So how about steam? So you go and get a steam cleaner (such as you use for carpet cleaning) and blow the steam into the apples. That works but as the butter starts to flow out it clogs the gaps and starts to re-harden except when the steam is right there. So you start to run the steam for a bit, stop and collect the butter that comes out, run the steam for a bit, etc. You can do this in an oil well and it has the exciting technical name of "Huff and Puff" (would I kid you?). (ask Your Government). To make the steam more effective it is heated to between 150 and 300 deg C. Where the rock is very permeable and the steam can, in time, work its way back through the particles (apples) this can recover a lot of our butter. But you still lose a lot of heat, which is expensive to generate, just in heating the apples.

What if we could use something else that does chemically what we have done with the heat? How about a soap? Yes that might work, the only thing is that soaps cost a lot of money and there really isn't that much butter, so unless we can get our soap back we really can't afford it. And what we have to do is to put in the soap, wait for it to work, and then push some water through to move the water:soap:butter to a place that we can collect and separate them.

Hmmm, but what if we had a chemical that could mix with the butter, and make it melt, so that it ran off without heat? That might be a lot simpler. Well it turns out that carbon dioxide, that gas we all love to hate, does exactly that.

(But now we have to talk just about oil). When carbon dioxide mixes with oil the resulting liquid has a larger volume, which means that it is thinner. (You could think of this as being the same sort of change as when you add a teaspoon of hot water to honey). The thinner oil is also less sticky and so it comes away from the rock more easily. So the thick sticky oil left in the rock becomes thinner, and will flows more easily. And tests, at the UT Austin (see yesterday), show that CO2 will move right through a rock of the right sort, reaching all the oil that might be there, and coughing up a lot more of it.

We can do the same sort of Huff and Puff approach that is used for steam injection, except using liquid CO2 and, in the right rocks we can get much more of the oil out. Or we can drill one well and pump in the carbon dioxide, and collect the oil and gas from the next well over. But there is an additional advantage. When we get through with pumping out the oil, we just pump all the carbon dioxide back into the rock and it stays there. So not only have we got the oil out, we have replaced it with the gas that is causing global warming, and once put into the rock it will stay there, in just the same way as the oil did. And what the experiments in China showed are that we can use the gases from power stations, without separating the components out, which would otherwise be a lot more expensive. What is also interesting is that the Chinese gases did not appear to have been liquefied, and that there might have been some production gain (up to perhaps 40% of the oil recovered) by combining the flue gas with steam.

Which leaves us with that apple, and the butter. Why don't you spread the butter on two slices of bread, slice the apple on top of one of them. Sprinkle blue cheese crumbs on the top of the apple, put the second slice of bread on top and have lunch – you deserve it, and (like me) you don't have to go the sandwich shop today.

(Technophiles can read a less dramatic version of the above here.).
* From a play here.
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Ask Your Government - the link's broken.

The reason we are using CO2 is because they have tried the others such as Soap. I fail to see where trying to get every last drop is going to lesson the impact of Peak Oil. If anything this would make the drop after Peak Oil even worse.

Face it NOW is the time for all governments to come together and start developing a real long term solutions before this whole comes up and smack the world up side the head.

The failure of the worlds leaders to do something now will only cause greater hardships later. Currently I do not see this happening and forsee major conflicts ( some are already here ) over Oil instead.

If you have not started planning and teaching your children to live of the land I suggest you do so today. Those who do not take heed to the many warnings out there will be pretty much up the creek without a paddle.

Personally I do not think most people realize or grasp what is about to happen to the modern world as they know it. I wish you all LUCK!!

fatbear-the link is fixed...

Errr - I'm confused by the metaphor now, but assuming I've interpreted it correctly - how much difference do you project these sorts of techniques would make to economic (from an EROIE point of view) extraction of oil from tar sands ?

Care to perform an update to the ASPO depletion model ?

Critical pressure of N2 is 493 psia and critical pressure of CO2 is 1071 psia. A 80/20 N2/CO2 mixture would be above the mixture critical pressure if they're injecting at 1000 psia. The N2 content might even be aiding the flow by lowering the critical pressure.

These analogies / metaphors involving food are really confusing me and getting me really hungry. Confusion + Hunger is not a good combo for explaining your case. Now, excuse me as I find my way to the fridge...


Bear in mind that it takes a very specific type of reservoir for this type of program to work. It is not a panacea - it is actually a relatively rare occurrence to find enough residual oil in the right type of reservoir to justify the increased expense.

Nobody knows how long the injected gases will remain in-situ. Gases tend to migrate much more readily than oil, and always upwards. We have already encountered "carbonated water" law suits...


"We have already encountered "carbonated water" law suits..."

Would you care to explain that? I'm quite interested

There were a couple of lawsuits out west by ranchers claiming that their water had been "carbonated" by injection of CO2 from nearby oil fields. I do not know the outcome - I just remember reading it years ago in a reception area magazine in Denver.

This is entirely possible in the Rockies. I have seen (with my own two eyeballs) oil companies drill into rock on one side of a mountain only to have their drilling mud appear on the other side via faulting and unknown geology, pouring down a stream bed. Mountain drilling is tricky to begin with - you never really know what has become interconnected in the middle of all the faulting.

I certainly wouldn't expect the injected CO2 to remain in place indefinitely, especially in a place where there is active earth movement, like the Kern River Valley in California...and one has to wonder what will happen if that much CO2 is suddenly released en masse. Is it an eco-bomb for some future time when the earth shifts? After all, it is the earth shifting that creates all our oil reservoirs in the first place.

Thanks. I gather that disasters like lake Nyos in 1986 aren't to be expected, are they?

That was the result of volcanic activity in/under a very stagnant lake. There is no correlation with CO2 injection.

That being said, release of CO2 en masse could be very deadly under the right geologic conditions. I would imagine a slow leak much more likely, where the CO2 simply leaks out from the reservoir into some other strata, following a fault.

JD -

"Luck is not a factor..."