WESTERN CANADA BASIN CONVENTIONAL GAS RESOURCE ESTIMATED AT 232 TCF

G.E. Reinson, P.J. Lee, J.E. Barclay, T.D. Bird, K.G. Osadetz
Geological Survey of Canada
Calgary

An estimate of 232 tcf of conventional undiscovered gas resources for the entire Western Canada Sedimentary basin indicates that more than half of the total gas resource remains to be discovered.

This preliminary figure results from the main resource potential study. Conventional Gas Resources of the Western Canada Sedimentary Basin, being conducted by the Geological Survey of Canada.

The study is the most comprehensive project of its kind undertaken by GSC because of the enormity of the pool database, the number of plays, and the geological complexities of those plays.

The basin encompasses practically all of Alberta, Northeast British Columbia, southern Saskatchewan, and southwestern Manitoba. Hence it was necessary to divide the overall assessment into play groups using geological criteria, primarily major stratigraphic time/rock units, and structural/tectonic provinces.

These major play groups are Devonian, Permo-Carboniferous, Triassic, Jurassic, Lower Cretaceous, Upper Cretaceous, Tertiary, and Foothills.

The resource evaluation methods used in the Western Canada gas project were developed within the GSC." Recent examples of the statistical procedures, as well as the terminology used, are documented in other works. 3 4

GSC has periodically prepared estimates of resource potential since the late 1970s using systematic geological basin analysis combined with numerical evaluation methods.3 4 5

PROJECT STATUS

Geological delineation of all plays within each major play group has been completed. Statistical estimations of undiscovered resources using the Petrimes methodology 2 have been completed for all major play groups except Cretaceous and Tertiary.

The data presented here on undiscovered resources for the Cretaceous and Tertiary are derived from published estimates for Alberta 6 and unpublished estimates for British Columbia and Saskatchewan. 7 Discovered in-place volumes for each major play group come from provincial databases incorporated into the Geological Survey of Canada's Petrimes database system.

Several comprehensive GSC bulletins similar to one on the Devonian' are scheduled for completion in the next 18 months. The Triassic gas study 8 is in final editing, and three other segments are at the manuscript production and compilation stage. 9 10 11

EARLY RESULTS

Discovered and estimated undiscovered in-place gas volumes are given for each play as is the total for each play group (Tables 1-5).

Plays have been named after the principal geological controlling factor(s) such as formation, depositional style, or trap type; in many instances, play names also contain the name of the gas pool that best typifies that play.

A summary table contains the total discovered and the estimated undiscovered in-place gas volumes for the entire Western Canada Sedimentary basin (Table 6). These summary results are illustrated in the pie diagram (figure).

It appears that the majority of the undiscovered gas occurs in Devonian, Cretaceous, and Foothills play types. It should be emphasized that the Foothills play group contains all of the major structure controlled plan,s, regardless of reservoir age . These include very significant Triassic, Carboniferous, and Devonian gas plays (i.e. Table 5, Triassic-Sukunka play).

SUMMARY

Although the Cretaceous Tertiary play groups have not vet been subjected to the same Petrimes methodological assessment as the other play groups, it is believed that the overall assessment of 232 tcf presented here is reasonable, perhaps even somewhat conservative.

It is thought that such an estimate, however preliminary, may be useful to industry and governmental policymakers alike.

ACKNOWLEDGMENTS

The authors thank G. Mossop, Institute of Sedimentary and Petroleum Geology, and B. Young, National Energy Board, for their constructive comments on this manuscript and their support and encouragement to publish these interim results. We are also grateful to K. Drummond of the NEB, who supplied the undiscovered gas in-place estimates for the Cretaceous and Tertiary play groups.

REFERENCES

1. Lee, P.J., and Wang, P.C.C., An introduction to petroleum resource evaluation methods, Canadian Society of Petroleum Geologists short course notes, 1990 CSPG Convention on Basin Perspectives, Calgary, May 1990, 108 p.

2. Lee, P.J., and Tzeng, P., The petroleum exploration and resource evaluation system (Petrimes) reference guide, Version 3.0 (PC version), GSC Open File No. 2703, 1993.

3. Podruski, J.A., Barclay, J.E., Hamblin, A.P., Lee, P.J., Osadetz, K.G., Procter, R.M., and Taylor, G.C., Conventional oil resources of Western Canada (Light and medium), Part 1: Resource Endowment, GSC Paper 87-26, 1988, 125 p.

4. Reinson, G.E., Lee, P.J., Warters, W., Osadetz, K.G., Bell, L.L., Price, P.R., Trollope, F., Campbell, R.I., and Barclay, J.E., 1993, Devonian gas resources of the Western Canada Sedimentary Basin-Part 1: Geological play analysis and resource assessment, GSC Bull. 452, 1993, 128 p.

5. Procter, R.M., Taylor, G.C., and Wade, J.A., Oil and natural gas resources of Canada, GSC Paper 83-31, 1983, 59 p.

6. Energy Resources Conservation Board, Ultimate potential and supply of natural gas in Alberta, ERCB Report 92-A, Province of Alberta, Calgary, 1992, 34 maps, 12 appendices, irregularly paginated.

7. Drummond, K., National Energy Board.

8. Bird, T.D., Barclay, J.E., Campbell, R.I., and Lee, P.J., in press, Triassic gas resources of Western Canada Sedimentary Basin - Geological play definition and resource assessment, GSC Bull.

9. Barclay, J.E., Lee, P.J., Holmstrom, G.D., and Campbell, R.I., in preparation, Carboniferous and Permian gas resources of the Western Canada Sedimentary Basin - Play Definition and Resource Assessment, Geological Survey of Canada Bull.

10. Holmstrom, G., Reinson, G.E., and Lee, P.J., in preparation, Jurassic gas resources of Western Canada Sedimentary Basin, GSC Bull.

11. Osadetz, K.G., Hannigan, P., and Lee, P.J., in preparation, Gas resources of the Canadian Cordillera, GSC Bull.

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