Thursday, December 3, 2015
Extensive analysis in Colorado, which requires water sampling both before and after energy drilling, shows no evidence of groundwater contamination that can be attributed to hydraulic fracturing. Earlier, methane contamination was found in a few wells and attributed to oil and gas drilling. However, research revealed that the contamination 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, studies 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 gas for more than three decades. Newer wells are subject to stricter well casing requirements and more frequent monitoring to prevent methane leaks. Authors of the study, conducted by researchers at Colorado State University (CSU), noted their analysis isn’t the first to report that “the sky isn’t falling” regarding groundwater contamination from energy activity. Outside Colorado, the Environmental Protection Agency and Yale University both released studies in the past year confirming that hydraulic fracturing itself is not responsible for water contamination.
In early November Colorado Water Watch, a CSU-based group of researchers that monitors water quality at oil and natural gas sites in real time, released the second part of a study that attempted to discern the source and mechanism for methane-contaminated wells that were identified in the first part of the analysis. Most of the methane found in groundwater wells was clearly shown to be from biogenic sources such as underlying coal beds, and most wells in the area showed no methane contamination at all, either from natural or oil and gas activities.
The study sought to determine the mechanism of the limited contamination, either gas migrating along a borehole that was not properly sealed with cement or a breach of the three layers of casing that protects aquifers from the hydrocarbon fluids being extracted. The iconic fingerprint in the oil- and gas-contaminated wells was compared to produced water obtained from nearby oil and gas wells and uncontaminated aquifer sources nearby. There was no evidence of aqueous contamination. Therefore, it was concluded that methane found in groundwater was likely due to a few poorly sealed well bores of indeterminate age.
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 gas for more than three decades. Newer wells are subject to stricter well casing requirements and more frequent monitoring to prevent methane leaks. Authors of the study, conducted by researchers at Colorado State University (CSU), noted their analysis isn’t the first to report that “the sky isn’t falling” regarding groundwater contamination from energy activity. Outside Colorado, the Environmental Protection Agency and Yale University both released studies in the past year confirming that hydraulic fracturing itself is not responsible for water contamination.
In early November Colorado Water Watch, a CSU-based group of researchers that monitors water quality at oil and natural gas sites in real time, released the second part of a study that attempted to discern the source and mechanism for methane-contaminated wells that were identified in the first part of the analysis. Most of the methane found in groundwater wells was clearly shown to be from biogenic sources such as underlying coal beds, and most wells in the area showed no methane contamination at all, either from natural or oil and gas activities.
The study sought to determine the mechanism of the limited contamination, either gas migrating along a borehole that was not properly sealed with cement or a breach of the three layers of casing that protects aquifers from the hydrocarbon fluids being extracted. The iconic fingerprint in the oil- and gas-contaminated wells was compared to produced water obtained from nearby oil and gas wells and uncontaminated aquifer sources nearby. There was no evidence of aqueous contamination. Therefore, it was concluded that methane found in groundwater was likely due to a few poorly sealed well bores of indeterminate age.
