A new study by the U.S. Environmental Protection Agency (EPA) found that pneumatic controllers on oil and natural gas wells in Utah may produce significantly fewer emissions of methane and volatile organic compounds than the agency previously assumed.
EPA’s recent study on pneumatic controllers in the Uinta Basin in Utah found that measured emissions from equipment in the basin were well below the estimated emission factors the agency uses to calculate greenhouse gas inventories, which are the basis for global reporting on air emissions. EPA found that the average actual reading was 97 percent lower than the agency’s standard emission factor for so-called intermittent bleed devices, despite including high bleeds and malfunctioning controllers.
Pneumatic controllers are used in oil and natural gas operations for production process control and safety. The EPA said it conducted the field study to improve the information available on pneumatic controllers and emission measurement methods used at oil and natural gas well pads.
“The Uinta Basin pneumatic controller study is the latest in a series that have consistently demonstrated emissions from this type of equipment are much lower than previous EPA estimates,” said Ryan Streams at Western Energy Alliance, which helped EPA refine the study’s scope. “We’re pleased to see research supporting what industry has been suggesting for some time now.” The Alliance supports Western Wire.
The study, published as “Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions,” recorded emissions from pneumatic controller systems on 80 wells over six days, with a focus on intermittent bleed (IPC) equipment. The team of researchers from EPA and a North Carolina firm found that on average, the pneumatic controllers they studied emitted 0.32 standard cubic feet of natural gas per hour (scf/h).
“The average IPC emission rate estimate of 0.32 scf/h was significantly lower than the GHG Inventory IPC emission factor of 13.5 scf/h per device,” the researchers wrote.
The EPA Inventory of Greenhouse Gas Emissions and the 2014 Uinta Basin Emissions Inventory consider pneumatic controls to be major emission sources. However, those inventories rely on emission factors that many have disputed as being too high.
“We’re hopeful that EPA will take this study along with the growing body of scientific evidence as an opportunity to revisit its emission factors for pneumatic controllers,” Streams said.
