Water wells recovering amid energy slowdownJan 23, 2014 By Mead Gruver, The Associated Press
CHEYENNE -- There may be a silver lining to the Powder River Basin's coal-bed methane bust: A new report shows water levels in some monitoring wells are rising now that gas production is falling.
Many ranchers saw their stock wells and even their home drinking water wells go dry during the coal-bed methane boom that began 15 years ago. Now that it has ended, there's hope that the trend of sharply falling water tables might also be waning.
A report released Tuesday by the Wyoming Geological Survey shows falling water levels in about three-quarters of 62 wells the U.S. Bureau of Land Management uses to monitor groundwater in the various coal and sandstone layers that underlie the basin.
Water levels rose in 15 of the wells, however.
"The results are pretty localized, I think. But you can see some trends in different coal zones," said Jim Stafford, a Wyoming Geological Survey geohydrologist who helped analyze the BLM data.
The latest of three groundwater monitoring reports over the past decade examined groundwater levels between January 2010 and October 2012.
The last report also showed some recovery in the monitoring wells and might have captured the beginning of the trend. That report looked at water levels from 2006 to 2009, by which time the rate of well abandonment in the basin had begun to outpace the new wells drilled.
Last year, companies abandoned more than 2,500 wells and spudded only around 100.
Coal-bed methane development depletes groundwater by pumping large volumes of groundwater out of saturated coal seams. Methane dissolved in the groundwater condenses out as it's pumped, not unlike how carbon dioxide condenses out of a soda bottle after it's opened.
The basin's coal-bed methane wells pump so much groundwater into streams and draws that local ranchers typically can make only limited use of it -- even as the wells they rely on for their cattle and homes go dry.
"I think it pretty much has stabilized now," rancher Bill West said of the groundwater in his area.
Four artesian wells on West's land 45 miles northwest of Gillette have to be pumped. The water that once flowed freely is now 120 feet below the surface, he said.
Companies have abandoned all but a handful of the 100 or so coal-bed methane wells on the ranch, West said.
According to the Wyoming Geological Survey report, coal-bed methane production in the basin fell 36 percent from its peak in January 2009 until the end of the latest groundwater monitoring in October 2012. Byproduct groundwater produced from coal-bed methane wells declined 59 percent from peak water production in October 2006 until October 2012.
Yet the correlation between decreasing gas production and rising water levels is inconsistent.
The water level in one monitoring well fell almost 180 feet even though nearby coal-bed methane wells produced a relatively small amount of water, about 96,000 barrels. In another monitoring well, the water level rose 79 feet while nearby coal-bed methane wells produced more than 1.3 million barrels of water.