The development of shale energy resources has created concern about potential impacts to the environment, while also leading to a societal awakening for the protection of our natural resources, especially water resources. There are potential impacts to the environment, for example if a spill occurs or a well is not constructed properly then water resource impacts could occur. On the other hand, shale gas has a lower carbon and water footprint than other forms of fuel. So while not perfect, it can be argued that it is a cleaner source of energy if developed properly. There are multiple waste streams that result from shale energy development. These include solid wastes such as drilling cuttings and sludge from wastewater treatment, and liquid waste streams such as flowback and produced fluids. Therefore proper treatment and disposal are critical. There are also phases during the drilling and fracturing operations that could lead to water contamination. For example the drilling and well construction process has led to methane migration where private wells have increased levels of methane originating from shale wells that were not properly sealed. Methane migration (aka stray gas) has been especially problematic in some of the early Marcellus shale wells drilled in northeastern Pennsylvania. Shallow gas was present in the upper 3000’ feet of the Earth, but not sealed off sufficiently, and leaked off into private wells. Through 2015 about 38 shale gas wells had impacted approximately 108 private wells in Pennsylvania, however stronger well construction regulations have decreased these numbers in the last several years. To put this in context, there were approximately 9,600 shale wells drilled through 2015 in Pennsylvania. Therefore 99.6% of the wells drilled had no reported methane migrations issues, but the 0.4% that did needed to be remediated and was surely a major inconvenience to those homeowners involved.
Review the compliance and stray gas sections (p. 19-21) of the 2015 PaDEP annual oil and gas report. Do you think the regulations and enforcement are improving with time?
The USEPA has been studying the risks to drinking water from hydraulic fracturing. To date there have been no documented cases of hydraulic fracturing fluids migrating up from the zone in the shale where fracturing occurs and leaking into a drinking water supply. However, there is no shortage of public concern about this occurring. There are other risks that are real and have been documented. Perhaps the biggest risk to impacting water resource quality from shale energy development is surface spills of fracturing or produced fluids. There are large volumes (millions of gallons) of fluids being handled during a fracturing job and a spills can occur, whether via mechanical failure or human error. The USEPA study is attempting to look at these risks and determine if they are a significant threat to drinking water.
Review the USEPA study’s executive summary (draft version). Do you feel there are significant risks? Can proper regulation and enforcement make these risks manageable?
While any form of drilling and oil and gas production does have inherent risks, there are many engineering practices that can minimize these potential risks. One of the most important means to ensure oil and gas development does not impact someone’s water supply is to collect pre-drilling water samples from their supply to establish baseline conditions. If there is a suspected problem after drilling or fracturing, then additional samples can be collected to determine if there is an issue related to the oil and gas operation. PaDEP has recommended parameters to be analyzed including the following:
If high levels of certain parameters occur in your water supply after nearby oil and gas development, there may have been some impact and remedial measures would need to be taken immediately. Again, although this is not common, it is much easier to prevent contamination than to clean it up. Some of the best management practices that the industry are now using to prevent spills and contamination include pre-drilling water supply monitoring, lining well pads to capture spills, and better well construction practices. As a citizen, if there is potential for drilling in your area become engaged in the process by contacting your regulator, attending public meetings, and being aware of drilling operation locations. Allow the oil and gas company contractors to sample your water at their cost and pay attention to the appearance, color, and taste of your water. If there is a change you will be able to detect it early and contact the regulators immediately to have it tested.