Coalbed Methane (CBM)
Coalbed methane, also known as natural gas from coal, is still in the early stages of development in Canada, producing about 23 million cubic metres per day. Western Canada's CBM now contributes over 20 million cubic metres per day to national production, and is forecast to increase to 85 million cubic metres per day by 2024.
About 19.8 trillion cubic metres of CBM resources are estimated to be prospective in Canada - roughly equivalent to corresponding United States CBM resources. However, only between 5 to 20% is recoverable using current technology. More research is necessary to assess its ultimate future contribution to Canada's natural gas supply.
The first Canadian commercial CBM production was established in 2003 in the Horseshoe Canyon formation in Alberta, which contains the world's largest deposit of “dry” coal, meaning little water is produced with the natural gas. For companies with Horseshoe Canyon coals, water handling costs are low and natural gas is produced soon after well completion. Most other CBM formations contain large amounts of water and the coals must be “dewatered” to maximize gas production.
CBM reservoirs are complex and each reservoir requires a unique approach. Some of the new technologies used to develop the Horseshoe Canyon formation are:
- Nitrogen fracturing treatments to stimulate natural fractures in the coals without damaging the fragile, dry and under-pressured coal formations;
- Multi-zone packer and cup-seal assemblies to deploy large numbers of nitrogen fracture treatments quickly and inexpensively;
- Low-cost, fit-for-purpose shallow gas drilling rigs (coiled tubing and conventional) originally developed for older shallow gas plays;
- Integration of large CBM developments within existing gas gathering and compression infrastructure, reducing capital costs.
CBM production has also been achieved in the Mannville formation coals in Alberta, which are deeper and contain much more gas than the shallower Horseshoe Canyon coals. Although still in the early stages of commercialization, production has been established in these coals using innovative horizontal and multi-lateral drilling and completion methods. The Mannville coals require de-watering to achieve commercial gas rates.
In Nova Scotia, a production agreement has been approved for CBM development. The Stellarton and Springhill basins are thought to contain in excess of 4.5 billion cubic metres of in-place gas in the coal seams, generally 1 800 to 2 400 metres below the surface.
Several other coals have significant CBM potential in Canada, including coals in Alberta, British Columbia, Saskatchewan, Nova Scotia, and the Yukon. As technology evolves, these coals will possibly contribute additional CBM reserves to Canada's gas supply.
