Abstract: Gas Reserves Growth in the Western Canada Sedimentary Basin

Kenneth J. Drummond

Recent studies, as the 1992 NPC Gas Study, highlight the importance of reserves growth in assessing the natural gas resource base for the United States. There are basic differences concerning reserves growth in the US and Canada. For the US, proved recoverable reserves are reported on a field basis, whereas in Canada data are reported on a pool basis, and includes estimated reserves for gas in place, recoverable gas and marketable gas, and are generally considered to be closer to the true ultimate, including proved plus a portion of the probable reserves. There are more factors which can impact reserve growth of United States gas fields versus Western Canada gas pools. Canadian pools can grow only through pool extensions and infill drilling. Improved technologies, recompletions, could increase recovery factors to be applied to the gas-in-place estimates.

Reserve growth curves for natural gas have been constructed for Western Canada and the United States. The cumulative growth factors are 8.5 for the US, and 3.0 for the Western Canada Sedimentary basin. For the US, growth occurs over a period of 60 years, with 80% of the growth achieved in about 30 years. For the Western Canada Sedimentary basin, maximum growth is attained in about 15 years, with 80% of the growth in the first 3 years. The impact of reserves growth on the ultimate gas resource for Western Canada is considered to be minimal as new pool discoveries for the last few years have been small. Reserve growth is included in the assessment of future gas potential for Canada by the National Energy Board.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994