Researchers in a peer-reviewed study conducted over three years have discovered that more methane is being emitted from Permian Basin natural gas gathering lines than previous federal estimates. 

In a peer-reviewed study published by the American Chemical Society, aerial data was used to measure emissions from thousands of miles of gathering pipeline in West Texas and parts of New Mexico.

“The rapid reduction of methane emissions, especially from oil and gas (O&G) operations, is a critical part of slowing global warming,” researchers said. “However, few studies have attempted to specifically characterize emissions from natural gas gathering pipelines, which tend to be more difficult to monitor on the ground than other forms of O&G infrastructure.”

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The study was conducted by researchers from Stanford University, the University of Arizona, the Environmental Defense Fund and Carbon Mapper, which tracks greenhouse gas emissions.

The gathering line emissions totaled at least 213,000 metric tons/year, or about 14 times higher than estimates by the U.S. Environmental Protection Agency (EPA). 

The emissions were equivalent to 2.7 metric tons/year for each kilometer of pipeline kilometer. One kilometer is equal to about .62 of a mile.

15% Of Leaks = Half of Emissions

Small leaks accounted for most of the emissions, researchers said. Fifteen percent of the leaks accounted for about one-half of the total emissions detected.

Emission measurements were collected from four aerial campaigns in the Permian Basin, the largest O&G producing region in the Lower 48. Estimates were made using a methane emission factor, which in this case was between 2.7 and 10.0. 

Findings showed methane emissions were “14–52 times higher” than the EPA’S national estimate for gathering lines. The results also were four to 13 times higher “than the highest estimate derived from a published ground-based survey of gathering lines,” the researchers said.

Aerial data collection, they noted, “allows for a greater sample size than ground-based data collection and therefore more comprehensive identification of emission sources that comprise the heavy tail of methane emissions distributions.”

The results indicate “the importance of a large sample size when calculating basinwide pipeline emission factors. 

Separately, researchers led by the University of Michigan recently reported that natural gas flaring from operations in the Permian, Eagle Ford and Bakken shales does not work as efficiently as it could, with as much as 10% routinely unlit or malfunctioning.