Beyond the Headlines: How Safe Is Our Drinking Water?
Do shale oil and gas drilling present a real threat to drinking water supplies? This is likely the single greatest concern in the minds of those opposed to the exploitation of this resource. Can oil and gas wells leak fluids into the Earth? Yes. Can it be prevented? Yes, again.
In this essay, we will discuss the mechanisms involved, the measures to prevent these occurrences, and the most recent scientific studies on the topic. On the last point, I am happy to report that, to date, the news is uniformly very good. Happy because this resource must be developed in a sustainable fashion. It has transformed the United States economy and improved the lot of every US citizen. We have a duty to get it done right. Other countries with similar resources need the US to succeed.
There are two potential sources for contaminating fluids. One is the hydraulically fractured zone in the reservoir and the other is the vertical portion of the wellbore. Microseismic monitoring involves “listening” to the minor tremors generated by the hydraulic fracturing operation. Thousands of such operations have been monitored and fractures do not extend more than 1,000 ft in a vertical direction. Leaving a margin of error, 2,000 ft of vertical separation ought to be sufficient. Most producing zones are at vertical depths greater than 4,000 ft, and fresh water rarely extends beyond a few hundred feet.