Letters from engineers

Feb. 1, 2012
Support for standards Thank you so much for publishing your new eBooks. I especially enjoy the zero registration aspect for easy access. My favorite issue

Support for standards

Thank you so much for publishing your new eBooks. I especially enjoy the zero registration aspect for easy access. My favorite issue is the Standards topic published in July — practical, informative, interesting, and very good for use as a teaching aid. Are other subjects available?
Richard McAfee

Other topics are available for direct download at http://motionsystemdesign.com/techapters, and that site will be updated with four more topics in 2012. — Ed.

The following letter is in response to a recent editorial (In the Loop, December 2011) about hydraulic fracturing for gas extraction.

Fracking requires more scientific study

Opponents of the hydro fracture technique of gas production use the term “fracking” in just the derogatory fashion mentioned in the editorial for good reason: This is likely to be the next big disaster in the making.

The basic technique is a sound idea — inject water at high pressure into a gas-containing layer of earth and fracture it so that the gas is forced out. Were water the only material injected, the calculation would be simple: See how much water it would take to produce a given amount of gas, and decide if that makes sense in the particular location.

With the addition of chemicals to increase the amount of gas extracted, the equation gets more complex. Several assumptions are made in order to claim that this is safe in terms of avoiding ground water contamination. These include the idea that fracturing is localized to the strata of interest (and others close by); the overlying layers are free of defects such as cracks and fissures that allow propagation of material to other layers; there is sufficient distance from aquifers in the region; and the well grouting is without defects.

All of these assumptions are questionable at best. There is no such thing as a natural formation without defects. The vertical distance that fracturing will be contained within depends on pressure and the type of rock. Making a well that doesn't leak under high pressure is not easy. Making a thousand such wells that don't leak doesn't happen. The anecdotal data suggests that this technique pushes material all the way to the surface. The incidence of contaminated wells and gas bubbling up in streams is too high to be a coincidence.

The current rush to drill wells is an attempt to get ahead of regulation. Like most situations where there is an extraction rush, the people and companies involved will get their rewards and leave behind a mess for others to deal with. The hidden cost of contamination is a cost that is transferred from the balance sheet of the extractors to the balance sheets of the neighbors, water users, and ultimately the taxpayers.

We need to do the experiments to see how far injected material spreads. The injection wells and test wells (water wells in the area) already exist. Two or more reputable third parties need to be brought in to several of these projects to do the work. This extraction method is moving too fast and the risks are too high to put off doing the science.
Mike Beaver

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