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I visited with retired geologist Grant Thayer after the BOCC’s 11-28 approval of the Sylvester Well permit, and asked him about my analysis of the adequacy of the oil & gas drilling related water quality testing protocol of testing existing wells in the vicinity of well bores, which in most cases would be shallow drinking wells.
The conclusion I had previously reached was that in the majority of Elbert County, the proposed testing protocol – which as it turns out is now a statewide rule in review at the COGCC – would only reach wells in shallow aquifers, leaving water in the deeper aquifers largely untested. The expensive alternative would be to drill a water well into all aquifers penetrated by an oil & gas well in the vicinity of that well, where such water wells do not already exist.
Thayer maintained this expensive alternative is not necessary due to differential pressures underground at different depths. As you go deeper in the ground, the weight of overlying rock is cumulative. Imagine the weight of 1 cubic foot of sand resting on your toe, and the weight of a couple thousand of them all stacked up in a column resting on your now extremely thin toe. (I asked Grant if he had a write-up to explain these physics and he said he did not, so you’re stuck with my non-geologist analogies.)
Now imagine a water balloon loosely filled with water. When you push down on one end of the balloon, thereby increasing pressure on that end, the water moves to the other end. In an environment of both low and high pressures, fluid will move to the lower pressure.
Fluid outside of a well bore casing that has escaped through a breach will migrate to the lowest pressure outlet – the surface. On its way it will be traceable in a lower pressure shallow aquifer first, before it shows up in a high pressure deep aquifer.
So even though untapped deep aquifers are not monitored for contamination, monitoring of the overlying shallow aquifers should be sufficient to indicate a well bore breach, because that’s where contamination would show up first.
Other things being equal, Thayer’s explanation appears to put my concern to rest.
I also asked Grant about a claim one of the speakers in the public comments segment made, suggesting that static levels in shallow aquifers are lowered by mining water from deeper aquifers. He said this is a popular myth and that removing the fluid from different aquifer structures has no effect on levels in other aquifers.
Grant nodded an interest when I asked him what he thought about the recent application of fracturing technology to water wells, and the effect this will have on existing water grants and adjudications from the Colorado State Engineer, all predicated on pre-frac (lower) recovery expectations.
B_Imperial
RE: Sylvester Well Permit, From: Southwest Energy
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“As of September 30, 2012, Southwestern has approximately 302,000 net acres in the Denver-Julesburg Basin in eastern Colorado where the company has begun testing a new unconventional oil play targeting middle and late Pennsylvanian to Permian age carbonates and shales. The company has completed a horizontal well and a vertical well, both of which are testing multiple intervals. Evaluation will continue on these two wells over the next 90 days. Southwestern is permitting and plans to drill additional wells in the area in 2013.
Last updated 11/05/2012″