[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:
>
>      "I don't agree that the energy added by the fracking wells is small."
>
> 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).
>
> coyote
>
>
>
> >________________________________
> > From: fossrme <fossrme@...>
> >To: geology2@yahoogroups.com
> >Sent: Monday, July 15, 2013 12:02 AM
> >Subject: [Geology2] Re: Quake Primer wasEarly Warning Signs ..Long
> >
> >
> >
> > 
> >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.
> >
> >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.
> >
> >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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