Coal Bed Methane: Gas Boom, Environmental Bust

by Walter R. Merschat

The following "Perspective" was published by The Casper Star-Tribune August 29, 1999 and is reprinted with permission.

On April 13, 1995, I stepped out of a car on a dusty road in the northern part of the Ute Indian Reservation in the San Juan Basin of Colorado. I stood on the road for several seconds peering up into the sky trying to find the jet I could hear overhead. Generally, with several head nods to lock onto the origin of the sound, an aircraft or vapor trail is easily spotted. I couldn’t get a fix; it sounded like several aircraft in all parts of the sky. The other door to the car slammed and my geologist friend directing the tour said "It’s methane, Walt. It’s venting methane."

We were halfway up the road through Dead Mouse Gap at the time. I was working for some landowners who brought a lawsuit against Amoco Oil Company for causing explosive levels of methane to collect in their homes as a result of Amoco’s coalbed methane program. Dewatering of the coal seam to release and produce methane through the well bore also released methane to the surface that collected in homes, bubbled up in the river, killed vegetation and saturated the shallow soil with so much methane that rodents were asphyxiated. Dead Mouse Gap was one of the methane venting areas.

On April 30, 1999, I stepped out of a car at a ranch located about 20 miles south of Gillette. I walked to the north side of the ranch house and got an instant fix on the hissing sound. Not an aircraft, but a water well. Methane was venting from the top of the well casing and creating a hissing sound now and then interrupted with a geyser-like frothing gurgle. "This is new," the rancher said. "Several years back this well was fine."

The coalbed methane boom that is spreading across parts of the Powder River Basin of Wyoming and Montana is in its infancy and is out of control. There are about 1,000 wells on stream now with as many as 15,000 pending permits. Already 20,000 acre feet of water has been pumped out of the coal aquifer and with a life of 12 to 15 years for the project, hundreds of millions of barrels of water will be removed and either dumped into an existing drainage system or stored in newly created ponds or reservoirs.

Ducks, fish and plants will flourish until industry turns off the water and the pseudo-environments return to pre-existing conditions. Recently, another rancher friend of mine attended a coalbed methane fair where industry suggested the ranchers affected by this new surplus of water should take advantage of it. "Try growing cranberries, try hydroponic tomatoes; how about beer?" they offered. "What about ranching?" was her reply.

Coalbed methane extraction represents a new technology. The 10-year track record of coalbed methane development in the San Juan Basin has caused explosive levels of methane to be vented to the surface, killed 100-year-old trees, lowered groundwater levels, ruined water sources, killed wildlife and recently has been linked to underground coal fires that belch carbon dioxide, hydrogen sulfide and methane to the surface, where temperatures reach 500 degrees F.

Studies are ongoing to determine the extent of the coal fires. Who will pay the millions of dollars it may take to extinguish the underground infernos? Industry is oblivious to the environmental disasters it is causing. State and federal agencies are blinded by their drive to fill the vaults with royalty money and sheepishly respond to pending environmental catastrophes by proposing to mitigate the debacles as they occur. When I speak out about my concerns, I get pretty much the standard response that the geology in the Powder River Basin is different than the San Juan Basin so the things that happen down there can’t happen up here. I agree the geology is different, but it does not insulate us from pending environmental devastation.

Dewatering
In both basins the principle is the same, i.e., remove enough water from the coal and gas will be liberated and produced. The water produced in the Powder River Basin is potable and will be stored on the surface or dumped into drainage systems. Pseudo-environments will flourish. Millions of barrels of good water will be lost from the aquifer. Groundwater levels will be lowered. Water wells (both pumping and artesian) will be lost. Sure, the operators will drill another well to replace the lost well, but what are we doing here? Millions of barrels of water that could grow millions of bushels of grain down the drain. I don’t think that is a conscientious or wise use of groundwater.

Aquifer Recharge
What happens to the aquifer after 12 to 15 years of pumping out hundreds of millions of barrels of water? Since groundwater is part of the structural fabric of an aquifer, removal of the water can cause aquifer degradation. In parts of California, Mexico, South America, Europe and elsewhere, uncontrolled dewatering of shallow aquifers for agricultural, industrial and domestic purposes has resulted in aquifer compaction and lowered the ground surface as much as 15 feet. Surface features (homes, roads, buried utilities, pipelines, etc.) have been impacted. The aquifer is permanently damaged.

I am concerned that dewatering may permanently damage the aquifers in the Powder River Basin. Preliminary studies in the San Juan Basin suggest the aquifers do not collapse. This is good/bad news. If these studies hold true and the structural integrity of the aquifer remains unchanged, the good news is that aquifer recharge is possible. The bad news is that natural recharge will take about 200 years.

Methane Venting
Dewatering not only reduces pressure in and near the well bore to permit gas production, but dewatering also lowers groundwater levels on a regional basis. This loss of pressure permits methane to vent to the surface away from wells. Explosive levels of methane can collect in buildings; surface areas where methane is venting can be ignited; vegetation and wildlife can be asphyxiated. The hissing hills on the Ute Reservation are venting nightmares. Amoco bought out the problem they created in a portion of the San Juan Basin.

I have measured elevated levels of methane in the soil near coalbed methane operations in the Powder River Basin. Will the levels of methane increase with increased dewatering activity? I think so. Who will be responsible for a disaster if and when it happens?

Coalbed Fires
There are presently five underground coal fires burning in the San Juan Basin. One fire has been burning for many years, while the other four are new. The four new fires are a result of spontaneous heating, better known as spontaneous combustion.

At this time the fires are located along the edge of the coal where dewatering has lowered the groundwater and exposed the coal to a combination of oxygen and moisture. Spontaneous combustion results and subsurface coal fires work their way through the coal seam, often accelerated by the addition of venting methane. The hills of Pennsylvania around Pittsburgh are spotted with areas of dead vegetation and belching noxious fumes from sub-surface coal fires. The city of Centralia, PA, was evacuated due to underlying coal fires. The coal in Pennsylvania is different than Powder River Basin (and San Juan Basin) coal. Pennsylvania coal is of higher rank and termed anthracite. Powder River Basin coal is of a lower rank and called bituminous. Bituminous coal is the most susceptible to spontaneous combustion.

During the recent past coal fires burned vast amounts of coal in the Powder River Basin leaving over 1,600 square miles of "clinker" (red ash-like baked rocks) beds behind. The geologic setting of the Powder River Basin coal and the San Juan Basin coal is different. Powder River Basin coal deposits are thicker and relatively flat, while San Juan Basin coal is thinner and at a steeper angle. These differences are supposedly what will prevent renewed spontaneous combustion from occurring in the Powder River Basin.

I think the differences make the Powder River Basin coal more susceptible to spontaneous combustion since dewatering of a flatter-lying coal seam will expose more coal to oxygen and moisture than coal situated at an angle.

What are we doing here? Concerns for the environment have been drowned in a sea of well permits. Does the natural balance of the Powder River Basin have standing? Does industry have the right to disrupt and possibly permanently damage the hydrologic cycle in vast parts of Wyoming and Montana? Do federal and state agencies have the right to approve the coalbed methane operations and jeopardize the natural balance of an ecosystem? I don’t think so.

__________________________

Walter R. Merschat lives in Casper. He is the owner of Scientific Geochemical Services, and has 30 years’ experience in the oil and gas exploration industry. He holds an MS in geology from Ohio University.