Study reveals hydraulic fracturing in Colorado basin did not change the rate of groundwater contamination
Posted: July 25, 2016
The University of Colorado published a study, which concluded that “wellbore barrier failure, not high-volume hydraulic fracturing in horizontal wells, is the main cause of thermogenic stray gas migration” in Denver-Julesburg Basin of Colorado.
This region has a 60 year history of hydraulic fracturing, with horizontal drilling and high-volume hydraulic fracturing beginning in 2010. Archived geochemical data from 1988 to 2014 was used to review the sources and occurrences of groundwater methane. Of the 924 sampled water wells in the basin, 593 sampled wells show dissolved methane that was microbially generated, likely from shallow coal seams. There were 42 water wells found to contain thermogenic stray gas. This stray gas was determined to be from underlying oil and gas producing formations, in which inadequate surface casing and leaks in production casing and wellhead seals in older vertical wells was identified as the pathway of leakage.
The archived data shows that the rate of water wells affected by thermogenic stray gas in the Denver-Julesburg Basin was about two cases per year from 2001 to 2014. The rate did not change after the introduction of horizontal drilling combined with high-volume hydraulic fracturing operations in 2010.
The study’s lead author, Owen Sherwood, a research associate at the University of Colorado with the Boulder Institute of Arctic and Alpine Research, stated, “Accidents do happen, but they’re relatively rare. Newer wells are typically constructed to be less prone to failure.” Sherwood further stated, A breach almost always occurs when a well is not properly constructed in the first place, and that fact hasn’t changed with the introduction of fracking.”
The study is a National Science Foundation-funded AirWaterGas project, a team of scientists, engineers, public health experts, educators, policy analysts, economists, and lawyers working together to address how to better integrate information about the environmental, economic, and social tradeoffs of oil and gas development into policy guiding and regulations governing development.