Coalbed Methane Development in the Western Canadian Sedimentary Basin: A Significant Emerging Resource for North America
Allan, Daniel K., APF Energy, Calgary, AB
The development of coalbed methane (CBM) within the Western Canadian Sedimentary Basin is in its infancy. Within the last year, several large commercial projects have been announced. This development is occurring in two distinct geological areas. The majority of activity involves CBM production from the Upper Cretaceous Horseshoe Canyon coals. These low water saturation coals have attributes that are similar to tight gas reservoirs. The coals are low rank, sub-bituminous and occur at relatively shallow depths. Individual coal seams are thin with numerous seams being completed concurrently. Total gross coal thickness ranges from 10 m to 20 m. Gas content is highly variable with an average of less than 50 scf/ton. Development is generally on 160 acre spacing with upwards of 2 BCF of potential gas resource per section. This play type may contain more than 40 trillion cubic feet of potential gas resource due to its extensive distribution within Alberta.
A second major CBM development focus is targeting the coal seams of the Lower Cretaceous Mannville section. These coals are high volatile bituminous C and occur at depths between 800 m to 1200 m. Due to their higher quality and depth of burial, gas contents average 300 scf/ton. There are four widespread coals within a 50m interval and wells are usually completed in the two thickest middle members. There are at least eight Upper Mannville pilot projects underway in west central Alberta with the vast majority being conducted in joint ventures with large US based independents. The resource potential of these Lower Cretaceous coals is large with current estimates suggesting over 55 TCF of gas in place.