Putting to bed the notion that ozone production is just a hot summer day in the city phenomenon, a new study by the National Oceanographic and Atmospheric Administration (NOAA) has discovered that "health-threatening" levels have been found during the winter near the remote Jonah Field and Pinedale Anticline natural gas formation in northwestern Wyoming. More alarmingly, data points to the problem being global.
NOAA said that during the past three winters, ozone -- normally linked to hot weather and urban pollution -- has soared near the Jonah and Pinedale Anticline site. Now scientists at NOAA's Earth System Research Laboratory say they have solved the problem of how ozone can form in cold weather at levels threatening to human health.
NOAA scientist Russell Schnell, the lead author of the study, said the results are forcing researchers to rethink the mechanics of ground-level ozone production. The NOAA analysis, the first ever for rapid ozone production in cold temperatures, suggests that the problem could be more widespread.
"Rapid production of wintertime ozone is probably occurring in other regions of the western United States, in Canada and around the world," said Schnell. "Wintertime ozone could be forming wherever gaseous fossil fuels are being extracted in conditions similar to those at the Wyoming site."
The NOAA team found that ozone was rapidly produced on frigid February days in 2008 when three factors converged: ozone-forming chemicals from the natural gas field; a strong temperature inversion that trapped the chemicals close to the ground; and extensive snow cover, which provided enough reflected sunlight to jump-start the needed chemical reactions.
"It seems if you don't have fresh, bright snow, you don't get as much or any ozone production," Schnell told NGI. "In 2007 there were almost no exceedances. The only correlating factor was there was no snow. We've actually modeled that. With fresh snow, the sunlight bounces off of it and doubles the chemical reaction. In addition to the reflection, fresh snow also adds moisture, which gives an OH molecule that can trigger the reaction. The oil and gas companies, of course, wish this didn't happen because it is costing them a lot of money. It is very strange. Even though it is an unpopulated area, EPA [Environmental Protection Agency] regulations still apply."
Schnell added that it is pretty clear that the natural gas production process is responsible for this event. "The production is either leaking methane, NOX [nitrogen oxide] or VOCs [volatile organic compounds]," he said. "If you use enough sensors, you can see the reactions starting in the middle of the field and radiating out. The companies have been addressing the issue. A consortium of producers spent $100 million last summer cutting down their effluents. As a result, the Wyoming Department of Environmental Quality (DEQ) has said that emissions have gone down some."
EnCana Oil & Gas, which calls Jonah Field one of its key resource plays, said it is working with the Wyoming DEQ to reduce the impact of its operations. EnCana's production in the field averaged 613 MMcf/d during 3Q2008.
"This was not primary research," said Doug Hock, a spokesman for EnCana Oil & Gas. "What [NOAA] did was take Wyoming DEQ research from the past couple of winters and made some fairly broad, general conclusions about all gas fields using that data. Clearly, solid scientific research is needed in this area. EnCana has been working with Wyoming DEQ and is funding Wyoming DEQ air monitoring programs in Sublette County. We are looking at various technologies and ways of continuously reducing our air impacts."
Hock said the producer has a program to reduce pressure on its gathering lines, which has resulted to date in as much as a 30% reduction in VOC flash emissions from condensate tanks. In addition, he said EnCana has also conducted a field-wide facility consolidation that reduced the number of tank-battery facilities from what had been planned to be as many as 329 to fewer than 160.
The Wyoming DEQ first discovered the winter-time ozone issue and called in NOAA for analysis.
"We have increased our monitoring activities and have been working with the industry to both voluntary...and otherwise, reduce the precursor emissions to the formation of ozone," said John Corras, director of Wyoming DEQ. "We are moving very aggressively in looking at improved emission performance for wellhead operations, compressor stations and drill rigs. We are also working on developing monitoring tools to be able to tell us how good we are doing with our prevention and mitigation efforts. We are going to continue to manage that area very tightly as the development continues."
Corras told NGI that producers are improving their daily operations. "They are using best-available control technology on their dehydration units and condensate handling systems. They are also looking at after-treatment devices for diesel engines on drill rigs. In one case a company is using natural gas engines on all of their drill rigs," he said.
Schnell said the problem is nobody knows which particular effluent might be a trigger. "There might be a magic bullet. Something in this potpourri of chemicals has a trigger mechanism in it that is starting the ozone process," he said. "It is not an easy process to start, especially during the winter with the cold temperatures. Somebody is going to have to do more measurements, but they have not been done yet. This study is being done again this winter, but they are not going to do the chemical measurements that will really tell them what is going on. There are some very critical measurements that have to be done at some point. They are very high speed, intense measurements that measure a number of different things at one time, but they are not cheap."
The study confirmed that motor vehicle exhaust, industrial gases and other urban emissions, as well as natural sources, produce the chemicals that then form ozone. However, it was previously thought that direct sunlight and hot weather were also required for high ozone concentrations to occur. NOAA said it is for that reason that ozone is routinely monitored only between April and October in the United States.
But from January to March 2008 instruments near the Jonah Field and Pinedale Anticline showed that on 14 days ozone exceeded the EPA's standard of 75 parts per billion (ppb) averaged over eight hours. At times, single-hour averages topped 140 ppb -- rivaling peak summertime levels of 150 ppb measured in highly polluted cities. NOAA noted that the state of Wyoming issued its first ever wintertime ozone advisories during those months.
Located in Wyoming's Upper Green River Basin, the Jonah Field and Pinedale Anticline formation is one of the largest and most concentrated natural gas fields in the United States. NOAA pointed out that energy companies during 2007 extracted more than $4 billion worth of natural gas there -- enough to provide the needs of 17 million U.S. homes for a year.
The Jonah Field has been described as one of the most significant finds of natural gas in the United States. It was discovered in the 1970s, but companies at the time did not have the technology to get the gas out of the ground. The overpressured gas was locked in very hard rock and the technology wasn't yet available to recover the gas. In the mid-1990s McMurry Oil tested hydraulic fracturing applications there, known in the industry as fracing, which involved literally fracturing the rock open with pressure to release the gas. It worked, and production at Jonah Field began.
NOAA said U.S. wintertime ozone concentrations are usually in the range of 35-50 ppb. However, much stronger concentrations were found in the rural Upper Green River Basin during air temperatures as low as -17 degrees Celsius.
"We find that hourly average ozone concentrations rise from 10-30 ppb at night to more than 140 ppb shortly after solar noon, under the influence of a stagnant, high-pressure system that promotes cold temperatures, low wind speeds and limited cloudiness," Schnell reported in the study. "Under these conditions, an intense, shallow temperature inversion develops in the lowest 100 [meters] of the atmosphere, which traps high concentrations of ozone precursors at night. During daytime, photolytic ozone production then leads to the observed high concentrations."
Schnell said similar ozone production during wintertime is probably occurring around the world under comparable industrial and meteorological conditions. "Since we published, we've had four more natural gas production points around the country where this ozone problem has been identified," he told NGI. "The issue has even been found in basins with low natural gas production. I think we'll find a lot more locations. It is not rocket science; you put meteorology and geography together and add the effluents from a production operation and there you have it. We can predict hot spots."
He added that state and government officials appear to be cracking down. "Wyoming is being very tough on the producers right now. If it plays out like the normal ozone exceedances, then the people who are supposedly to blame will have to put together a plan and test it," he said. "If they don't, they eventually will have to curtail production when one of these events occurs, but I don't know how far the EPA or Wyoming will push this."
Among other likely areas for this problem are Russia, Kazakhstan, Mongolia and China, according to Schnell, who noted that ozone measurements in most of these regions are limited or nonexistent in winter.
A main ingredient of urban smog, ozone can cause severe respiratory effects, especially in children, the elderly and asthmatics. It also damages crops, trees and other vegetation. The EPA sets air quality standards for ground-level ozone pollution in the United States.
The development of the Pinedale area has been a hotbed for other concerns as well. In December the Bureau of Land Management released its final resource management plan for the Pinedale Anticline that melds protections for wildlife habitat while permitting more oil and natural gas exploration in the region (see NGI, Dec. 22, 2008; Sept. 1, 2008).
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