Contaminated water from shale gas is likely to be caused by faulty wells rather than the controversial process of hydraulic fracturing (fracking), researchers in the US have revealed. In a study published in The Proceedings of the National Academy of Sciences this week, the researchers highlighted seven cases in Pennsylvania and one in Texas where methane and other hydrocarbon gases had contaminated water wells. The researchers said there was no evidence that fractured shale resulted in contamination. Instead, the researchers believed that either the cement that sealed the outside of the vertical wells or the steel tubing that lines the them was at fault, causing the gas to leak into aquifers.
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