Real-time well groundwater monitoring

By Ken Carlson, CSU Civil and Environmental Engineering Professor

Colorado was the first state in the country to require water sampling both before and after drilling. But what happens to water during the fracking process itself?

To answer this question, in 2014 I teamed up with fellow researchers at Colorado State University (CSU) and launched Colorado Water Watch (CWW), a first-of-its-kind system that monitors water quality at oil and natural gas sites in real time.

We used the system to show proof of concept on 10 producing wells in the Wattenberg Field, which is largely located in Weld County. As Colorado’s largest producer of oil and natural gas, Weld County is the ideal region to analyze fracking’s effects on groundwater.

In each well, we placed sensors at varying depths. The sensors monitor water concentrations and send data directly to the CWW server every five seconds. Anyone can access this data online 24-hours a day.

In November 2015, we released the second part of a study that attempted to discern the source and mechanism for the methane contaminated wells that were identified in the first part of the study in Environmental Science and Technology. This initial study showed that less than 2 percent of the groundwater wells that were flagged to have at least 1 mg/L of methane were impacted by oil and gas activity. Most of the methane found in groundwater wells was clearly shown to be from biogenic sources such as underlying coal beds. It is important to note that most wells showed no methane contamination, either from natural (biogenic) or oil and gas activity related sources.

The second part of the study published early in 2016 in Water Research examined the wells that were contaminated with methane from oil and gas activity. The objective of the study was to determine the mechanism of the contamination, either gas migrating from the producing format along a borehole that was not properly sealed with cement or breach of the three layers of casing that protect the aquifer from the hydrocarbon fluids that are extracted. The ionic fingerprint in the oil and gas related methane contaminated wells was compared to produced water obtained from nearby oil and gas wells and uncontaminated aquifer wells also nearby.

Extensive analysis of the data showed no evidence of aqueous contamination. Therefore, it was concluded that methane contamination that has been found in a few groundwater wells and attributed to oil and gas activity was likely due to poorly sealed well bores, a practice referred to as cement bonding. Despite concerns of widespread casing failures after 20 or 30 years, this study could not attribute any of the contaminated wells to this mechanism.

The study did not differentiate the age of oil and gas wells that were in the vicinity of the methane contamination, but Weld County has been extensively drilled for oil and natural gas for more than three decades and newer wells are subject to stricter well casing requirements and more frequent monitoring, hopefully preventing future methane leaks.

The CSU study isn’t the first to report that the sky isn’t falling when it comes to groundwater contamination. Over two-dozen findings from governmental organizations, universities, and nonprofits confirm that fracking does not contaminate groundwater.

 

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Researchers: Fracking doesn’t contaminate groundwater