While the shale revolution may appear to have little in common with historical methods for oil and gas production, many similarities remain. And a new report in Proceedings of the National Academy of Sciences indicates that the risk of methane contamination does not appear to be any greater for today's modern shale wells than for the hundreds of thousands of conventional wells that proceeded them. The primary risk to groundwater, as it turns out, from the new wells and the old, appears to be defective casings. The fracking process itself does not increase the risk of methane contamination, according to the study, which was led by an assistant professor of geochemistry at The Ohio State University.
The Columbus Dispatch discussed the report's findings in detail in Fracking study: Correctly built wells don't contaminate water.