Potential coalbed methane resources in Atlantic Canada

Abstract

Thirteen coal areas of the Maritime Provinces in Atlantic Canada are estimated to contain some 2.23 trillion m 3 (78.8 TCF) [TCF, BCF, MCF: trillion, billion, million cubic feet]) of coalbed methane resources. This compares with 510 billion m 3 (18 TCF) of natural gas calculated for the Sable offshore resources in eastern Canada. In the United States, where coalbed methane resource evaluations and production have increased substantially over the past 20 years, 7% (1.34 TCF) of total domestic gas production is derived from coalbed methane. In this period, the cumulative US production of coalbed methane has exceeded 198 billion m 3 (7 TCF) and more than 8000 coalbed methane wells have been drilled. In Maritime Canada, the largest coalbed methane resources occur in the offshore areas of the Gulf of St. Lawrence and Sydney Basins where 196 and 26 billion m 3 (69 and 9.3 TCF) of gas, respectively, have been projected. In the old mines, the greatest resources are present in the Prince and Phalen mines of the Sydney coalfield, which together contain 1.70 billion m 3 (60 BCF) of gas, and in the Westville mine of the Pictou coalfield with 198 million m 3 (70 BCF). Vitrinite is the dominant constituent in 27 of the 42 coals examined. Vitrinite/inertinite ratios for these 27 coals range from 4.0 to 8.4. These high values may indicate the presence of highly fractured coals with corresponding high permeability and flow efficiency, favourable for the storage and flow of methane gas. Coal rank has a pronounced effect on coalbed methane generation, and the prime gas zone often lies between 1.2% and 1.6% Ro max. (medium to low volatile bituminous). The prime zone in the Maritimes Basin underlies much of the central and eastern Gulf of St. Lawrence, and extends for significant distances seaward into the offshore Sydney Basin. Coalbed methane production from the very large resources available in Atlantic Canada may provide a valuable and long-lasting energy resource, largely free of polluting components.