How Is Coalbed Methane Produced?
No two CBM sites are exactly alike. An area’s geological history and the depth of its buried coal determine a coal’s type and gas content. Still, conventional natural gas drilling techniques can develop almost any CBM deposit. However, before commercial CBM can be produced, testing is often completed on four or five wells in close proximity. On the surface, a CBM drilling system looks much like one used in any oil and gas operation. In many cases, it most closely resembles the equipment used to drill water wells. The cover photo shows the equipment used to drill a test well in the Elk Valley in southeastern B.C. during summer 2000. Underground, CBM’s production system is unique (Figure 2). Typically, a steel-encased hole is drilled into the coal seam first. Unlike conventional reservoirs, which will produce gas through the well bore at high pressures, simply penetrating the coal seam will not cause the CBM to flow. Generally, a fluid – sometimes a water-based nitrogen foam – must be pu
