Certain oil and gas operations that involve injecting wastewater underground can cause earthquakes, but the risk from hydraulic fracturing is generally low, said a US scientific report Friday.
The report by the National Research Council found that the most significant risk of earthquakes is linked to secondary injection of wastewater below ground to help capture remaining hydrocarbons from a petroleum reservoir.
Also, a technique called carbon capture and storage that aims to reduce carbon dioxide emissions to the atmosphere by capturing, liquefying and injecting them below ground at high volumes, “may have potential for inducing larger seismic events,” the report said.
But fracking, which offers the potential to unlock vast quantities of natural gas from shale formations and has come under intense scrutiny from environmentalists, was not a major risk factor for quakes that would be strong enough for people to feel, or above 2.0 magnitude, it said.
“The process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events,” said Murray Hitzman, a professor of economic geology at the Colorado School of Mines and chair of the committee that authored the report.
A spokesman for the National Academy of Sciences said the committee members all passed a screening process to rule out potential conflicts of interest, and all agreed with the conclusions in the report.
There are 35,000 wells for shale gas development in the United States today, and only one case has been documented worldwide in which hydraulic fracturing for shale gas was confirmed as the cause of nearby earthquakes, it said.