A study of shale natural gas plays in the United States finds some of the predictions for long-term growth may be overly optimistic, the journal Nature reports.

The U.S. Energy Information Administration expects shale natural gas production to increase through 2040. Advances in hydraulic fracturing, the drilling practice known commonly as fracking, has given energy companies a way to coax gas out of shale rock deposits that were previously out of reach.

Tad Patzek, director of petroleum engineering at the University of Texas at Austin, said a detailed analysis of U.S. shale plays may be "bad news" for forecasters, describing the EIA's forecast as optimistic.

Policymakers on Capitol Hill have said the glut of natural gas means the United States should transform itself as a major exporter of liquefied natural gas, arguing such deliveries may contribute to the rise of the country as an "energy superpower."

"We're setting ourselves up for a major fiasco," he said in an article published Wednesday by the journal.

The Marcellus, and its underlying Utica play, is behind the increase in shale natural gas production in the United States.

Bentek Energy, the forecasting unit of Platts, found gas production in the Lower 48 states averaged 69.9 billion cubic feet per day in October, breaking the previous record and posting the 10th straight month of gains.

Gas production in October was 7.9 percent higher year-on-year.

Texas researchers, however, said they've looked more carefully at the shale phenomenon than the EIA. Their forecast sees production from the four largest shale plays in the United States peak in 2020. By 2030, production is about half of what EIA analysis found.

Paul Stevens, an economist at Chatham House, told Nature the Texas study could have a spill-over effect on countries looking to replicate the U.S. success with shale.

"If it begins to look as if it's going to end in tears in the United States, that would certainly have an impact on the enthusiasm in different parts of the world," he said.