CBM is extracted by drilling a well into a coal seam applying similar techniques used for other natural gas wells. The sides of the well are "cased" with cemented steel pipe. Usually, small holes, called perforations, are then made in the wall of the casing to let the CBM flow through into the well bore and up the casing to the surface. In some cases the wells are drilled horizontally and the coal seams are often stimulated or "fractured" to make the CBM flow more freely. Standard drilling and extraction technology is used or adapted as conditions require.
Hydraulic Fracturing is explained in this fact sheet.
Potential in Alberta
The Alberta Geological Survey estimates there may be up to 500 Trillion cubic feet of natural gas in Alberta's coals. It is not known how much of this gas may be economic to produce. As more information becomes available the production potential will become clearer.
The majority of CBM development is taking place in the dry Horseshoe Canyon, more information on
development and legislation is available.
Alberta's geology - learning from projects in Alberta
As more wells are drilled in Alberta, we are getting valuable information about the potential and characteristics of associated water production, and a clearer picture of Alberta's geology.
In 2012, nearly all coalbed methane wells drilled in Alberta have targeted the thinner coal seams in the Horseshoe Canyon (ultimate gas in place 179 Tcf) and Belly River coal zones along the Calgary-Red Deer corridor. Wells targeting these seams tend to produce gas with little or no water, with production referred to as "dry CBM". The first commercial production of CBM in Alberta was from these coals, and they constitute the majority of CBM reserves booked. The depth range of these coals is 200 to 800 m.
The remaining CBM wells drilled have targeted the deeper Mannville coals (ultimate gas in place 321 Tcf). These coals tend to be thicker, deeper, and more continuous with substantial saline (salt) water production. The depth range of these coals is 900 to 1,500 m.
Most CBM wells in the Horseshoe Canyon Formation are vertically drilled wells, whereas most wells in the Mannville Group are horizontal wells.
The Energy Resources Conservation Board/Alberta Geological Survey completed a report on the Ardley-Paskapoo entitled “Preliminary Investigation of Potential, Natural Hydraulic Pathways between the Scollard and Paskapoo Formations in Alberta: Implications for Coalbed Methane Production”, it supports improved understanding of aquifer systems.