According to a study of Pennsylvania state inspection reports, newer and unconventional wells leak more often than their older and traditional counterparts. The report, published on June 30, 2014 by the Proceedings of the National Academy of Sciences, suggests that methane leaks could pose a problem for drilling across the nation.
Four scientists analyzed over 75,000 state inspections of Pennsylvania gas wells conducted since 2000. Their results found that the leak rate for hydraulically fractured wells—mainly constructed since 2006– had an approximately 4% higher leak rate than their counterparts.
The report has drawn criticism from the energy industry, with critics claiming that the report conflates pressure with leakage. The study attempts to draw a causal relation between the two, according to spokespeople for the industry, and the existence of the former is not evidence of the latter.
Pennsylvania regulatory officials have stated that while gas leaks peaked in 2010, the leakage rates have declined since then.