The reasons for worldwide fracking protests are manifold, but one area of particular concern is the likely long-term effects of unconventional drilling on groundwater aquifers.
Back in the old days of conventional drilling, it was economically feasible to capture up to 95% of the natural gas released from shallow rock deposits per well. With unconventional drilling in deep shale deposits, that figure is generally placed in the 30-70% range. Granted, 30-70% of the massive amounts of natural gas locked up in shale, combined with the number of wells being drilled, translates into an enormous amount of natural gas being captured, which is what all the recent crowing about shale gas production is about.
But not much is ever said about the 30-70% of shale gas which is released from the rock and stays in the ground. Where does it go? What does it do?
The natural gas that is released but not captured for human use is free to migrate where it will, including up the well-bore which facilitated its release, even after said well has been capped, and through whatever cracks and fissures, natural or man-made, it may find.
The gas industry would have us believe that between it and Mother Nature, the groundwater aquifers in shale country are completely protected. We are told that the layer of rock between shale and aquifer is totally and permanently impermeable. Not all geologists are in agreement on this. Seismic forces can lead to fissures where none existed previously.
But the main focus of natural gas advertising is on the layers of concrete and steel which are placed between the well-bore and the aquifer. That, we are told, will shield the aquifer from all pollution, be it methane or toxic flowback, forever. Not so. Failure of well casings to prevent leakage is figured at 6-20% from day one to year five of a well, even by industry sources.
But let's estimate the integrity of wells out 30 years, 50 years, 100 years. How well are those concrete and steel casings going to hold up? Think of your knowledge of the roads and bridges in western Pennsylvania. Steel rusts and corrodes. Concrete cracks and deteriorates. And that 30-70% of released natural gas will find those cracks and fissures eventually. Eventually there will be 100% failure of steel and concrete casings across hundreds of thousands of wells throughout Pennsylvania, throughout the Northeast, throughout the U.S., throughout the world. Aquifers will be polluted, by methane gas and by any residual toxic wastes from fracking that are not disposed of properly.
The “unconventional” wisdom of the gas industry seems to be: “Let's make a killing on the drilling now and clean up the mess later.” It may well be a mess unparalleled in the history of human existence.
Indeed, drilling is just the beginning.