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A reader writes:
Hydraulic fracturing has been around a long time. At least fifty years in the U.S. and at least forty in California.
Most people have no idea how oil drilling works and what percentage of oil is extracted from a well.
The rest of his very informative email is below the fold:
Oil is not just one big pool of oil like commonly pictured in schematic drawings; it is usually found in some sort of matrix of a rock formation. The amount of oil extracted is related to the porosity and permeability of the rock in which it is located.
Traditional drilling usually only recovers about one third the oil. Flushing the well with water generally produces another 10% or so. Fracking is a way to free some of the remaining oil from the rock in which it is located. In the case of shale, where most of the oil is located, the purpose of pumping the water under pressure into the well is to fracture the shale so that more oil can be pushed out of or flow out of the rock. When fracking was introduced, the drillers used to mix ground up walnut shells with the water. These were to prop open the fissures and cracks in the rock after the water left.
Basically, all the chemicals added to water to create each driller’s fracking fluid, is simply a refinement of the basic technique-making it easier to fracture the shale, and to keep the fractures open so the oil can get out.
Of course in some places fracking is being used even where there was no conventional drilling initially.
Right now the major oil shale areas are the Marcellus in Pennsylvania, the Bakken in North Dakota and the Eagleford in Texas. California which as you as a native know was swimming in oil and is still the third largest oil producing state in the United States (after Texas and North Dakota, but ahead of Alaska, Oklahoma and Louisiana) has a very large shale formation that underlies about a third of the state called the Monterey shale.
It appears as though shale formations throughout the U.S. are not uniform in their porosity and permeability, and in fact oil companies (with the notable exception of Occidental in the Central Valley) have not been able to use fracking to any great effect in unlocking oil from the Monterey Shale. Instead fracking has been used mostly in depleted wills which is how it has been used for forty years here. I assume that eventually through trial and error drillers will find the key to unlocking fracking for the Monterey shale, but its clear from looking at a map that certain areas (such as Marin County) are never going to be exploited.
None of the established modes of fracking that have been so effective in the U.S. has worked in other parts of the world. Again this is based on the specific make up of the shale. It’s only a matter of time before the proper techniques are developed.
One of the leaders in fracking technology is not an American company, but a Dutch Company, Core Laboratories.
There is another technique also being perfected. If you are capable of controlling an entire field, you can cap all the wells but one and inject carbon dioxide under pressure. At high enough pressure the very viscous oil absorbs the CO2 and the oil starts flowing freely. When the oil is brought to the surface the CO2, no longer being under pressure immediately boils off of the crude oil, and it can be captured, pressurized and reused. Something like 5% of oil in the US is produced this way today and it increases the percentage of oil extracted from the well by something on the order or additional 10 to 15% . If you are someone concerned about C02 concentration in the atmosphere, it also provides a possible way for carbon sequestration. Interestingly the C02 used for this purpose is mined, not captured from carbon fuel burning smokestacks.
It’s really a fascinating subject. My [career] is entirely unrelated to oil and gas. I am self educated in this, but its fairly easy to find people who know something about this to talk to and plenty of articles around as well. But the one thing that is clear to me, is that in general the people who oppose fracking don’t understand how it works. Instead, when you press them they are opposed to any further development of carbon based fuels. My favorite question to ask opponents (just as the question should also be asked of proponents) is what would you have to learn about fracking to change your position? Once it gets to that point, they generally admit they are opposed to any further development of carbon based fuels.
I don’t know if you saw Gasland II, but there is a really frightening sequence where some guy in Texas picks up his garden hose and it turns into a flame thrower. When I saw the movie I thought there is a hell of lot of methane in the water. As it turns out the guy connected his hose to a gas vent. He knew it was false and in a court case between the guy in the movie holding the hose and Range Resources the driller he was suing, there was a finding in the court case about how he set up the fraudulent filming of the gas coming out of the garden hose and he was sanctioned.
There are serious issues with Fracking but they boil down to four: (1) the environmental impact of taking existing surface or well water for use in the fracking process, (2) the environmental impact of the disposition of the fracking fluids once they have been repumped to the surface, (3) in the case where the fracking produces natural gas, the separation and capture of methane mixed with the natural gas and (4) the possibility that well casings might leak in which case either fracking fluids or oil could contaminate any aquifers through which the casing passes.
Its notable that so far there have no documented cases that cracked casings have led to pollution of underground aquifers. You might want to look at a photograph of a typical casing to understand why almost all casings develop cracks yet they haven’t leaked into the aquifers. (the answer is redundant concentric concrete). The claims of fracking forcing methane into drinking aquifers appear to be completely unfounded.