Regional evaluation of the coalbed-methane potential of the Foothills/Mountains of Alberta, Canada

Coal is present in the Alberta Foothills/Mountains in five zones: the Kootenay, Gething, Gates, Brazeau and Coalspur coal zones. For coalbed-methane (CBM) evaluation purposes, they can be divided into shallow (less than 1000 m depth) and deep (greater than 1000 m depth) coal zones. The potential gas content of all shallow coal zones totals about 878 × 109 m3 (31 Tcf) of CBM, which is considered an inferred, initial, in-place, coalbed-methane resource estimate based on limited data. The limited amount of data on formation testing and measured gas content indicate that the inferred resource is bordering on the speculative category.The gas content of all deep coal zones (deeper than 1000 m) totals 2.8 × 1012 m3 (about 99 Tcf) of in-place coalbed-methane gas. Consequently, the total ultimate coalbed-methane resource could be 3.7 × 1012 m3 (130 Tcf). However, coalbed-methane recovery from deep coals is generally not attempted because of the high cost of drilling and the low permeability that results from high overburden load and stress.The only (limited) Foothills coalbed-methane production has been from the southern Alberta Kootenay Coal Zone, which is very prospective for coalbed-methane production. The shallow Gates Coal Zone in the central and northern Foothills is also prospective, but needs to be better tested. The best potential for coalbed methane in the Coalspur Coal Zone is in the Edson area (Entrance Syncline and Triangle Zone). The Kootenay and Gates coal zones are not well defined in the northern part of the Calgary (NTS 82O) map sheet.