Some CBM wells produce only water

By DUSTIN BLEIZEFFER
Star-Tribune energy reporter Sunday, May 06, 2007

Pumping water from coal aquifers has long been regarded as necessary to produce the gas that resides in the coal. In the Powder River Basin, nearly 4 billion barrels of groundwater have been pumped through coal-bed methane wells and dumped on the surface to make it Wyoming's No. 1 natural gas producing region.

But what happens when wells pump water for two years -- more in some cases -- without the benefit of producing gas?

More than 14 percent of active coal-bed methane wells in the Powder River Basin in December were producing only water, according to the Wyoming Oil and Gas Conservation Commission. To date, more than 39,000 acre-feet of water have been produced from wells that have not produced any gas. An acre foot is enough water to cover an acre of land at a depth of a foot.

Agriculture, industry and regulatory officials appear to be in preliminary discussions about the possibility of establishing some sort of standard that would prevent unnecessary water production. It comes at a time when the state is under increasing pressure to get a handle on the volumes of water that are produced by coal-bed methane wells.

Although some of the water is put to beneficial use, such as stock watering and irrigation, most of it is not put to a specific beneficial use. In some cases, the water floods low-lying grazing pastures.

Now several companies are taking inventory of which wells contribute to overall gas production, and which wells might only add to water problems in the basin.

"There's a massive savings to the industry by doing things properly -- and to the environment," said Wayne Greenberg, CEO of Laramie-based Welldog Inc.

Welldog recently provided Gov. Dave Freudenthal with a more analytical breakdown based on public data collected by the Wyoming Oil and Gas Conservation Commission. Greenberg said some wells that produce only water still contribute to overall gas production because they help lower the hydrostatic pressure within a certain region that does result in gas production.

So the actual percentage of water-producing wells that don't economically contribute to overall gas production is debatable.

The low end, which doesn't seem to be in dispute, is 8.6 percent of all wells that have been in production for at least two years. Those wells pumped about 223 million barrels of water, or 29,000 acre-feet.

The high end, which some in the industry would dispute, is 39.3 percent. Factored into that percentage are water-producing wells categorized as not producing economic volumes of gas, and not located next to wells that are economic gas producers.

Regardless of how the wells and the numbers are split, both industry and agriculture are eager to apply more technologies that reduce the volumes of water produced. Ag producers want only what they can use, and gas companies want to minimize the cost of managing water on the surface.

Welldog, Big Cat Energy Corp. and about a dozen other companies are taking inventory for producers who want to find efficiencies now that the dust has settled from the coal-bed methane rush that began in 1998.

Greenberg said hundreds of companies swept into the area and bought up any lease that had coal under it.

"The sense in the industry then was to move fast and bring production on as quickly as possible. Now, there's more care taken," Greenberg said.

Rick Robitaille, spokesman for Anadarko Petroleum, said his company was asked by the Petroleum Association of Wyoming to determine how many of its wells might produce water without contributing to gas production.

Robitaille said in some areas it does require more "de-watering" to entice gas production, so water production rates vary greatly throughout the basin.

"It's all dependent on the characteristics of where they are and what the structure looks like," Robitaille said.

Energy reporter Dustin Bleizeffer can be reached at (307) 577-6069 or dustin.bleizeffer@casperstartribune.net.

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