Calgary�Estimates of undiscovered natural gas resources for northeastern British Columbia have dropped to 30.8 tcf from 33.2 tcf over the past 5 years, the Canadian National Energy Board reported.
NEB said the Foothills region is the most likely to yield large gas discoveries. Drilling activity in the region between 1992 and 1997 opened 2.5 tcf of initial marketable gas reserves. Adjustments based on drilling and reservoir reviews increased that estimate by 66 bcf in the period.
The board said drilling in northeastern British Columbia has rebounded from a low of 158 wells in 1992 to an average of more than 400 in the past 3 years.
During the 5-year period covered by the study, drilling activity resulted in 1,070 gas wells, 536 dry and abandoned wells, and 401 oil wells. The number of producing gas wells increased to 1,425 in 1997 from 886 in 1992.
The top three geological plays in the region ranked by average reserve addition size for new pools were the Pardonet-Grizzly Foothills, Pardonet-NW Foothills and Debolt-NW Foothills. The top three plays based on ultimate gas resources were Pardonet-Grizzly Foothills, Pine Pt.-Clarke Barrier and Halfway-Plains.
NEB said the annual conversion rate of undiscovered gas resources to proven reserves was about 1.4%, or a total of 7% over the 5 years.
It said the Foothills region is the most prospective for large gas discoveries. They are expected to exceed the average northeastern B.C. find of 6.5 bcf. Devonian plays in the northern part of the region should also yield discoveries larger than the average pool size for the region.
NEB said exploration activity must shift to the Foothills area to add the volume of reserves needed to meet or exceed production forecasts.
It said the Plains area of the region will continue to be attractive to drillers because of accessibility to existing infrastructure and a likelihood of finding new pools.