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Geologist: Coal outcrops cause methane hot spot
FARMINGTON — A major reason why a concentration of atmospheric methane the size of Delaware was recorded over the Four Corners area may turn out to be a matter of geology — not the oil and gas industry.
That was the consensus — and the hope — of many oil and gas representatives in the room during a presentation by Durango, Colo.-based geologist Ashley Ager on the final day of the Four Corners Oil and Gas Conference at McGee Park on Thursday.
Ager is a senior geologist with LT Environmental, Inc, an Arvada, Colo-based environmental and engineering firm that contracts with the oil and gas industry,
Ager said that a major source is likely to be numerous coal-bed outcrops where the sedimentary Fruitland Formation rises to the surface on the outer edges of the San Juan Basin.
The methane-rich coal-bed formation crops out around the north, west, and south sides of the San Juan Basin — sites Ager said are, at the very least, substantial contributors to atmospheric methane concentrations in the region.
"We have known (about) naturally occurring methane gas seeping out of the Fruitland Formation outcrops in the San Juan Basin," she said. "We've seen it for years. You can go back before there was any industry in the Four Corners, before mining, before oil and gas. The Southern (Ute Indian Tribe has) known that there are methane seeps in the basin for hundreds of years."
Since 2007, her group has led pedestrian surveys using a methane flux meter to measure the rate of gas coming out of the ground, a project that has mapped methane seeps. She said her group has not included Southern Ute lands or gone south of the border into New Mexico to continue documenting methane seeps, but hopes other organizations and students will join her effort. in the future.
Ager said her group's project to map methane seepage sources just south of Durango, Colo., gained greater relevance after a 2014 report by NASA and the University of Michigan using European satellite imagery captured between 2003 and 2009 that showed a large "hot spot" of atmospheric methane over the Four Corners. After that discovery, scientists started a project to better define the cloud's sources.
"Our opinion is that (Fruitland seeps) are a significant contributor to the methane 'hot spot,'" she said. "We can do calculations and say that there is a decent chance that the outcrops, just the (ones documented by her group in La Plata County, Colo.) contribute at least 15 percent of the emissions that the researchers calculated for the methane 'hot spot.'"
A follow-up study by scientists from the University of Colorado, the University of Michigan, the National Oceanic and Atmospheric Administration and NASA aims to more closely record methane levels in the region with the goal of pinpointing sources for the cloud. Results from that research are expected to be available this fall or early 2017, she said.
Ager showed video clips she said document methane bubbling up from waterways in the region, including one near Bayfield, Colo.
"A lot of (area) creeks bubble methane gas," Ager said, as the video showed vigorous bubbling in a shallow creek. "That's South Fork Texas Creek and that's creek gas bubbling up. That's how much there is. That's a lot. You can throw a match on (the creek) and it will light it up ... You can go behind Walmart (in Durango, Colo.) and throw a match on the Animas River where there's a methane seep and it will light up ... people have known about this for years."
Ager said her project's look at seeps from the Fruitland Formation — layers of shale, coal, sandstone, limestone and other sedimentary deposits left behind by the Cretaceous Sea roughly 73 million years ago — emit gas that can be a captured and used to generate electric power.
Ager's project, which was initially funded by the Colorado Oil and Gas Conservation Commission and now by BP, has captured 15,200 Mcf from four collection facilities and, with the help of a micro-turbine, transformed the gas into 236,000 kilowatts of surplus electricity, received by the La Plata Electric Association. That power could generate electricity for four or five homes, she said.
She said topography of the basin was a contributing factor.
"(The San Juan Basin) does produce a lot of coal-bed methane, and I think that's why people jump to a lot of assumptions about the methane 'hot spot.'" she said. "That's why oil and gas jumps out as a source. The thing you have to think about if you live here is that we have a topography that might be conducive to holding in some gases."
Two coal-fired power plants and two coal mines about 15 miles west of Farmington also contribute, she said.
James Fenton is the business editor of The Daily Times. He can be reached at 505-564-4621.