Evolution of Tight Gas Sandstone Plays and Production, Western Canada Sedimentary Basin

Brad J. Hayes
Petrel Robertson Consulting Ltd., Calgary, AB, Canada

Tight gas sandstone plays in the Western Canada Sedimentary Basin (WCSB) have been pursued and produced actively for several years. Exploration companies initially tried to adopt successful strategies from basins of the western United States, but found that many of these were not viable in the stratigraphic and structural regime of the WCSB. A broad spectrum of tight gas plays has now evolved in western Canada, as operators have developed new mapping, drilling and completion techniques to suit the geology of the basin.

WCSB tight gas sandstone reservoirs range from Triassic to Late Cretaceous age, and span depositional environments from distal turbidites to alluvial fan conglomerates. Three examples characterize the range of play types and strategies that have evolved in since 2001:

1. Nikanassin structural play - thick (up to >1000 m) fluvial to shallow marine sandstone-dominated section, with permeability enhanced by natural fractures associated with faulting in the Foothills. Multiple zones are fracture-stimulated and commingled.

2. Cretaceous multi-formation commingled play - reservoirs are evaluated in up to 10 separate formations, with production commingled from the 4-5 best zones in each wellbore. Regional mapping by formation is important in highgrading development areas.

3. Triassic siltstone plays - porosity associated with particular facies and diagenetic trends within the overpressured Deep Basin is exploited using horizontal and downspaced vertical wells, and advanced completion techniques.

Although the WCSB tight gas play spectrum is much different than that in the U.S. Rockies, huge gains in reserves and productivity have been attained with improved understanding of the reservoirs.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas