This is the Wiki article on HF. It is good read and seems balanced. I would note that this does not discuss radium and thorium which, like coal excavation are released into the environment with fracking fluid extraction. This is probably the most expensive contaminant to eliminate but the greenies haven't caught on to this as of yet.
It doesn't address the actual process step by step and that would be nice to have covered.
It doesn't address the actual process step by step and that would be nice to have covered.
http://en.wikipedia.org/wiki/Hydraulic_fracturing
Eman
From: MEM <mstreman53@yahoo.com>
To: "geology2@yahoogroups.com" <geology2@yahoogroups.com>
Sent: Monday, July 15, 2013 3:04 PM
Subject: Re: [Geology2] Re: Quake Primer wasEarly Warning Signs ..Long
I believe I addressed all this in the original post: pressure in the injection wells disspates over days to weeks into the pores of the rock strata it isn't just a static vessel pumped to max pressure.
I also tried to note there is a big difference in drilling/fracking tremors vs. those alleged actions which "trigger" quakes when "previously unknown" faults are reactivated. The energy potential is drastically different in scale. Potential energy comes from the pressurized water and, from stresses in the ground which may be there due to oil/gas extraction deflation or, from stressed ancient faults. The former are relatively small and the latter are small to medium as evidenced by the 5+ which happened in Prague, OK.
Think a rusty spring-loaded lever that has been sprayed with penetrating oil. Eventually, depending on how much tension in the spring and how well the oil dissolves the rust bonds the lever can swing at any time. With two blocks of rock, under tension and with a fault down the middle, the fluid slowly wedges them apart and lubricates the faces. When the friction is overcome(aka sufficiently relieved) , there will be a rupture along the fault.The study also addressed the potential for a distant large quake to trigger a swarm of tremors in an injection field followed by a larger quake in that field. This may have been the case in Prague, OK
Eman
From: fossrme <fossrme@yahoo.com>
To: geology2@yahoogroups.com
Sent: Monday, July 15, 2013 1:57 PM
Subject: [Geology2] Re: Quake Primer wasEarly Warning Signs ..Long
I was not under the impression that we were only talking about quakes that released "titanic" amounts of energy. Smaller quakes are much more common but they are still a problem. Many injection wells pump wastes for 10 years or more, which stores up a considerable amount of energy over time. If that stored energy is released suddenly it can be a significant jolt. We need someone to do the math on this, but I strongly suspect that the energy put into the ground is comparable in some cases to the energy released by the stronger quakes we see in the midcontinent area. It's all in the numbers, which we don't have.
--- In geology2@yahoogroups.com, coyote <coyote2@...> wrote:
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> Â Â Â Â "I don't agree that the energy added by the fracking wells is small."
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> Just to clarify, I don't recall anyone suggesting it was small (in absolute terms). I did suggest it (in relative terms) "is trivial compared to the energies in quakes" (which can be titanic).
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> coyote
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> >________________________________
> > From: fossrme <fossrme@...>
> >To: geology2@yahoogroups.com
> >Sent: Monday, July 15, 2013 12:02 AM
> >Subject: [Geology2] Re: Quake Primer wasEarly Warning Signs ..Long
> >
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> >Â
> >Regarding the discussion on this topic I would like to add a few comments as someone who worked for a number of years in the Underground Injection Control (UIC) program at EPA's Regional Office in Dallas. I retired before the practice of fracturing to recover gas really got into full swing but I know something about waste disposal wells, which were regulated by the agency.
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> >In most cases EPA oversees the States' implementation of federal programs that have been delegated to them, as is the case for most of the UIC program. The objective was to design and maintain wells so that they injected into a porous, confined zone at pressures that would not cause fracturing. Injection designed specifically to fracture rock over wide areas is still relatively new and potentially prone to unintended consequences.
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> >I don't agree that the energy added by the fracking wells is small. Fluids are injected at high pressures over a time span long enough to cause the rock to fracture even though it is overlain by tons of rock above that tend to keep it solid. For waste injection wells EPA required tests and calculations to show that the injection pressure would not be high enough to lift the column of rock on top of the injection zone. The fact that the injection wells were capable of delivering enough energy to lift that overlying rock column gives some idea of how much energy is involved.
> >
> >As for natural gas invading shallow water wells in fracking areas, the industry is having trouble passing the laugh test by claiming that the gas came from other sources. The gas has been traced directly to fracking operations, and might have moved up into the shallow aquifer by traveling up around the well casing.
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