Study: Natural Gas Drilling Emits Less Methane Than Previously Estimated

Mark Green
Posted September 17, 2013

A new, comprehensive study by the University of Texas, showing methane emissions from natural gas drilling are a fraction of estimates from just a few years ago, vouches for industry efforts to reduce methane emissions, suggests existing regulation is working and that an additional regulatory layer isn’t needed.

The UT study, sponsored by a group of interests that includes the Environmental Defense Fund and a number of natural gas producers, examined 150 production sites across the U.S. with 489 wells, 27 well completion flowbacks, nine well unloadings and four well workovers. Key findings:

• Overall methane leakage from natural gas production was 0.42 percent of total volume compared to EPA’s most recent estimate of 0.47 percent.

• Because of methane-reducing equipment, emissions from well completions are 97 percent lower than calendar year 2011 national estimates that EPA released earlier this year.

• Total U.S. emissions of methane from natural gas production are 10 percent lower than the most recent EPA estimates.

API’s Howard Feldman, director of regulatory and scientific affairs, said industry is succeeding in efforts to reduce methane emissions during natural gas production:

“The industry has led efforts to reduce emissions of methane by developing new technologies and equipment, and these efforts are paying off. This latest study shows that methane emissions are a fraction of estimates from just a few years ago. The industry will continue to make substantial progress to reduce emissions voluntarily and in compliance with EPA’s recent emissions standards. Capturing methane is helping operators deliver more natural gas to consumers, creating a built-in incentive to continue reducing these emissions.” 

The study, published in The Proceedings of the National Academy of Sciences, is significant because it is the first to examine individual drilling sites. Previous EPA estimates relied on engineering calculations, while other efforts used data collected by aircraft flying over drilling sites. ExxonMobil spokesman Richard Keil told the National Journal:

"It's very good news. This is a groundbreaking survey. It's the most extensive one that's been done yet, and it serves to add important new evidence that hydraulic fracturing does not contribute to climate change – it does not contribute methane emissions at levels higher than those set by the Environmental Protection Agency."

The UT study indicates federal, state and local regulations already in place are being effective. The study’s estimates are lower than EPA’s most recent estimate – which itself was dramatically lower than previous estimate. The study:

The work presented here suggests practices such as combusting or capturing emissions from completion flowbacks, as required by New Source Performance Standards … and the revised National Emission Standards for Hazardous Air Pollutants … are resulting in reduced methane. emissions.

A chart from the study showing declining emissions:

Feldman said additional regulation on top of existing rules isn’t necessary. The study found emissions at wells during the completions phase – when sand and liquids injected into a well to fracture natural gas-bearing shale is cleared – are on average 50 times lower than previously estimated by EPA. Feldman said the result bodes well for extending an American energy renaissance that has resulted largely from production from shale using hydraulic fracturing and horizontal drilling: 

More studies no doubt will follow. Certainly, a fact-based discussion of energy production using hydraulic fracturing benefits all – as America’s vast reserves of natural gas and oil found in shale and other tight rock formations are safely and responsibly developed.