Houston (Platts)--19Feb2013/326 pm EST/2026 GMT

A multi-agency study released Tuesday finds that oil and gas operations in the Uintah Basin were responsible last winter for releasing into the air the great majority of precursor chemicals that combine to form ozone, a pollutant that has vexed the basin over the past several winters.

An emissions inventory, conducted as part of the 285-page study that measured ozone levels in the basin during the winter of 2011-12, found that oil and gas operations were responsible for 98-99% of the volatile organic compounds and 57-61% of the nitrogen oxides emitted from all sources studied. Ozone is principally formed as the result of the VOCs and NOx reacting together in sunlight.

The study was conducted by the Utah Department of Environmental Quality, in association with the US Environmental Protection Agency, US Bureau of Land Management, National Oceanic and Atmospheric Administration, Utah State University, the University of California, the University of Colorado at Boulder, Western Energy Alliance and other entities.

Study organizers gathered in Vernal, Utah, Tuesday to announce the launch of the second phase of the study, which will continue to monitor ozone concentrations in the basin through the current year.

Brock LeBaron, a spokesman for Utah DEQ, cautioned that it is too early to determine if the results of the study indicate the need for increased regulation of the oil and gas industry in the basin.

The existence of precursor chemicals in the atmosphere "doesn't necessarily mean that those precursors are going to lineally form ozone," he said. "You have to look at other sources of VOCs and NOx as well."

The results of the emissions inventory "gives us a basic understanding," of the types of VOCs oil and gas operators are releasing into the atmosphere, but "it doesn't tell us how important they are," in leading to the formation of ozone, LeBaron said.

"Right now we're not passing any new rules or regulations. We're not saying you have to control these VOCs from this piece of equipment," he said.

Instead the DEQ is urging operators to use the best available technology to control the release of both VOCs and NOx.

In fact, the winter of 2011-12 was a period of low ozone formation in the basin, compared with the previous two winters, LeBaron said. Last winter was very warm, and the region did not have any snow cover or temperature inversions, conditions necessary for the formation on wintertime ozone.

However, the lack of ozone may have aided the scientists in other aspects of their investigation, he said. "It allowed the researchers to identify what types of emissions are in the basin. That's easier to do when you have a clean atmosphere," he said.

Kathleen Sgamma, WEA's vice president of government and public affairs, said the study findings that the oil and gas industry was responsible for the production of the majority of VOCs and NOx in the basin was not surprising.

"In the Uintah Basin, pretty much the only activity is the oil and gas industry," she said Tuesday. "We knew all along that oil and gas was the major source of emissions in the basin."

However, she added that more work needs to be done to develop the inventories for other potential emissions sources, such as motor vehicle traffic, in the basin.

Western Energy Alliance provided $2.125 million toward the Uintah Basin ozone studies, through contributions from Anadarko Petroleum, Berry Petroleum, Bill Barrett Corp., EOG Resources, Gasco Energy, Newfield Exploration, QEP Resources, and XTO Energy.

--Jim Magill, jim_magill@platts.com --Edited by Katharine Fraser, katharine_fraser@platts.com