Where future Canadian gas supply will originate

Dec. 15, 1997
Natural gas from Canada is becoming an increasingly important component in the North American gas market. Future supplies of natural gas from Canada will come, first, from the Western Canada sedimentary basin and southern Ontario and Quebec ( Fig. 1 [121,867 bytes] , Category A), where all current gas production is obtained and where the producing infrastructure is in place. Secondly, gas will come from the frontier basins in Canada, where gas discoveries have been made but where neither
Robert A. Meneley
Canadian Gas Potential Committee
Calgary
Natural gas from Canada is becoming an increasingly important component in the North American gas market.

Future supplies of natural gas from Canada will come, first, from the Western Canada sedimentary basin and southern Ontario and Quebec (Fig. 1 [121,867 bytes], Category A), where all current gas production is obtained and where the producing infrastructure is in place.

Secondly, gas will come from the frontier basins in Canada, where gas discoveries have been made but where neither production nor transportation infrastructure is in place (Fig. 1, Category B).

Finally, future gas supplies will be drawn from frontier basins where potentially productive sedimentary rocks are known to be present but where exploration to date has not yielded any discoveries (Fig. 1, Category C).

Canada's gas supply

Remaining marketable gas in Canada, including discovered reserves and undiscovered potential in established exploration plays and coalbed methane, totals 570 tcf. The estimate is based on yearend 1993 reserves information and is stated on a 1,000 Btu/cf basis.

The geographic distribution of gas resources is shown on Fig. 2 [68,302 bytes]. Table 1 [28,736 bytes] describes the discovered and undiscovered potential in terms of both gas in place and marketable gas. No specific assessments have been made, but there is additional potential in conceptual exploration plays in frontier basins where no discoveries have been made. Also, unconventional gas potential will be found in tight gas reservoirs, shale gas plays, hydrates, and additional coalbed methane beyond that included in the estimates.

The Canadian Gas Potential Committee recently published a comprehensive analysis of the gas prone exploration plays in Canada. The committee is made up of a volunteer group of experienced oil industry professionals who conducted this detailed assessment of gas potential during 1991-97.

The study describes each of the established conventional gas exploration plays in Canada in terms of the discovered gas pools in the play, the size of undiscovered pools in the play, and the map outline of the play area. Separate estimates of coalbed methane potential have been included as well.

The information on each play is stated as gas in place with an estimate of marketable gas based on the statistics for the discovered pools in each play. No economic cutoffs have been applied. The study is intended to provide a sound, technically based estimate of undiscovered potential on which studies of gas supply, timing, and exploration effort can be based.

A unique peer review process was developed to permit play-specific industry input into the assessments while maintaining the confidentiality of the input provided along with the independence and responsibility of the committee for the final assessment results.

In the Western Canada sedimentary basin, where most of the currently available conventional gas resources are located, eight play groups contain 82 assessed exploration plays (Fig. 3 [64,282 bytes]). Table 2 [37,573 bytes] describes the details of in-place and marketable gas for both discovered and undiscovered pools. An estimate of the number of undiscovered pools is included as well. The assessment methodologies used permitted the estimation of both the total undiscovered potential in each play and the size ranges of each of the undiscovered gas pools. Such information will permit analysts to judge the amount of drilling effort that will be required to discover the resources and to calculate the volumes that may be developed under various economic scenarios.

The four largest play groups in the Western Canada sedimentary basin contain more than 80% of the undiscovered gas potential. The plays within the Jurassic to Lower Cretaceous play group are expected to contain 32 tcf of marketable gas in clastic reservoirs in many thousands of undiscovered gas pools. In eastern Alberta, where most of the potential is located, the largest undiscovered pools are in the order of 16 bcf. The small pool size is offset by the number of multiple pools discovered in a single well bore.

The Foothills play group, Middle Devonian play group, and Upper Devonian play group collectively have a mean undiscovered gas potential of 31 tcf in new pools. These play groups have the largest undiscovered pools that range in size from 1-4 tcf of gas in place. The potential is concentrated in the western part of Alberta and in the Alberta foothills. Reservoirs are deeply buried and are typically highly productive. The gas contains important volumes of condensate which add to the value, but this is offset by the hydrogen sulfide and carbon dioxide that are found as well.

With the exception of the three play groups discussed above, the undiscovered potential in conventional gas plays will be contained in many thousands of relatively small gas pools. Coalbed methane resources will require advances in technology to permit their economic development. As a result, future gas supplies from the Western Canada sedimentary basin will require high levels of exploratory and development drilling and application of improved technology. The large undiscovered potential that is present will become available in relatively small increments.

Frontier basins

Canadian frontier basins include all of the sediment-covered areas outside of the Western Canada sedimentary basin. They offer a widely diverse array of prospects. Discoveries have been in the Category B areas highlighted on Fig. 1 which contain the most obvious and readily defined exploration plays and prospects. The undiscovered potential in the exploration plays in these areas has been assessed by the Canadian Potential Gas Committee. Fig. 4 [64,373 bytes] shows the combined discovered and undiscovered potentially marketable gas in the discovery areas. No gas production or transportation infrastructure is available in any of the frontier basins. The initial Hibernia oil development in the Jeanne D'Arc basin off Newfoundland will produce associated gas that will be reinjected and used as fuel. A development proposal for some gas fields in the Sable sub-basin is currently under consideration. If that proposal is approved, offshore Nova Scotia will deliver Canada's first frontier gas production. Discovered gas fields in the frontier basins have high quality reservoirs and have tested impressive gas flows. The fields, in most part, have been partly delineated with drilling and seismic. Each of the Category B discovery areas outlined on Fig. 1 have unique challenges in terms of access and operating environment. Gas supplies from each of the areas will only be forthcoming when those challenges have been met and the economically attractive portion of the discovered gas reserve is developed. The remaining Category C areas in the frontier basins have been explored to some extent without success. The geology is not as favorable as in the Category B discovery areas. Gas discoveries will be made with future exploration, but their contribution to Canadian gas supplies has a high level of uncertainty and a long time line.
This article is based on Natural Gas Potential in Canada, 1997, published by the Canadian Gas Potential Committee, P.O. Box 20032, Bow Valley Square, Calgary, Alta. T2P 4H3. Ph: (403) 781-5599. Fax: (403) 781-5598.

The Author

Robert A. Meneley has been the chair of the Alberta Region of the Canadian Gas Potential Committee since 1993. He is a consultant who has worked on a wide array of Canadian and international projects. As vice-president of exploration for Petro-Canada and Panarctic Oils Ltd. he directed Canadian and international exploration programs from 1973-84. From 1956-72 he worked for Imperial Oil Ltd. on surface geological studies in the Rockies and northern Canada, subsurface geology in northern Alberta and British Columbia, and in the East Coast offshore. He has a BSc degree in geological engineering and MSc degree in geology from the University of Saskatchewan. E-mail: [email protected]

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