Hydraulic fracturing to increase gas output has a fraction of a 1 percent chance of causing unintended cracks in the earth beyond 600 meters (656 yards), according to research in Marine and Petroleum Geology.
Hydraulic fracturing, or fracking, has opened vast shale gas deposits and helped push U.S. gas prices to the lowest level in a decade. It involves injecting water, sand and chemicals into deep shale formations to break apart underground rock and free natural gas trapped deep underground, a technique that some critics have said risks contaminating ground water aquifers.
The research published in the scientific journal today, led by Durham University and based on data from thousands of U.S. fracking operations and natural fractures in Europe and Africa, showed the odds of “rogue” cracks extending beyond 350 meters at 1 percent, according to a statement from the university.
“The process itself is a bit of a red herring in terms of the chance of it causing aquifer contamination,” Richard Davies, a co-author of the report, said in an interview. “The earth is very good at limiting these things.”
The researchers, also from Cardiff University and Norway’s University of Tromso, recommended regulating a minimum vertical distance between gas reservoirs and aquifers for stimulated fracturing. In areas where the technique has not been used, it should be “significantly in excess” of 600 meters, they said.
“The chances of rogue fractures due to shale gas fracking operations extending beyond 0.6 kilometres from the injection source is a fraction of 1 percent,” according to the statement.