An article to be published in an upcoming issue of Geophysical Research Letters includes research suggesting that contamination of potable groundwater through fractures and faults in the hydraulic fracturing process is extremely unlikely. The research gauges the upper limits of vertical fracture growth by comparing fracture heights that have been inferred from microseismic observations to theoretical calculations. Specifically, the microseismic events that were analyzed were all less than 600 meters above well perforations, and most distances were much smaller.
The estimated areas of sheer displacement, including faults, were comparatively small, with radii in the range of ten meters or less. This indicates that fracture heights are limited by fracturing fluid volume regardless of interaction between the fluid and faults. The limits on fracture growth and fracture-fault interactions suggest that direct hydraulic communication between tight formations and shallow groundwater is not a reasonable expectation, implying that groundwater contamination via hydraulic fracturing is unlikely.
The microseismic data set includes over 12,000 hydraulic fracturing stimulations from over 25 oil and gas development basins across North America. This set of basins includes ‘tight’ formations, such as black shale, tight sandstone, and tight carbonate formations. The research was conducted by Samuel Flewelling, Ph.D., and Matthew Tymchak, M.S., scientists with Gradient Corp., an environmental and risk science consulting firm.