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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Facts and Principles of World Petroleum Occurrence — Memoir 6, 1980
Pages 993-993
Symposium Abstracts

Deep Basin Gas Trap, Western Canada: The Container for Elmworth: Abstract

John A. Masters1

Gas accumulations are distributed in a similar fashion to most other natural resources. The high grade deposits are comparatively small. In general, as the grade decreases the size increases.

Three of the largest sandstone gas fields in western North America are in low porosity - low permeability Cretaceous sands, in down-dip structural locations, with porous, water filled reservoir rock updip. Examination of the details of these fields sets the stage for recognizing an enormous tight sand gas trap in western Canada.

The Mesozoic rock section, only 300 m (1 000 ft) thick on the shelf in eastern Alberta, thickens westward to over 4 500 m (15 000 ft) in the deep basin in front of the Foothills overthrusts. Most of the developed sandstone gas fields are in updip porosity traps, or minor structural traps, on the shelf. The porous, generally water saturated sands of the shelf become less porous and permeable westward and downdip, passing from the water bearing area with local gas traps through a transition zone to a gas bearing area. This change is demonstrated by electrical resistivity logs and confirmed by drillstem tests.

Recent exploratory drilling in the deep basin has resulted in numerous discoveries in the area. Several hundred log analyses provide reliable data for measuring potential gas supplies in the range of 11.3 × 1012m3 (400 tcf). Recoverable gas at $2.00 per mcf net after royalty may reach 4.22 × 1012m3 (150 tcf).

The quantities of gas apparently present would be a major addition to the North American energy supply.

Acknowledgments and Associated Footnotes

1 Canadian Hunter Exploration Ltd., Calgary

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