--> Abstract: Stratigraphy and Petrography of Viking Sandstones in the Bayhurst Pool and Surrounding Areas, Southwest Saskatchewan, by Carrie Kreutzer-Walz, Per Kent Pedersen, and Guoxiang Chi; #90039 (2005)

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Stratigraphy and Petrography of Viking Sandstones in the Bayhurst Pool and Surrounding Areas, Southwest Saskatchewan

Carrie Kreutzer-Walz1, Per Kent Pedersen2, and Guoxiang Chi1
1 University of Regina, Regina, SK
2 Saskatchewan Industry and Resources, Regina, SK

The Albian Viking Formation is an eastward prograding wave dominated clastic wedge underlain and overlain by marine shales. Oil and gas pools in the Viking Formation consist of stratigraphic and structural traps within linear sand bodies, generally oriented northwest – southeast, mimicking the shoreline as it moved landward and seaward with changes in relative sea level. This study focuses on the Bayhurst gas pool, Townships 23 to 26 and Ranges 24W3 to 28W3, an area of about 87 square miles, and time equivalent strata along the shoreline and basinward.

Core and well log cross-sections, together with sedimentary facies maps, illustrate the stratigraphic and reservoir architecture of the Bayhurst gas pool, characterized by units separated by flooding surfaces, sequence boundaries and ravinement surfaces. The reservoirs include sandstones of a retrograding barrier island system, which unconformably overlie shoreface and shelf deposits, and of a younger incised valley fill. The reservoir is capped by transgressive marine shales of the Westgate Formation. Preliminary petrographic studies indicate Viking sandstones can be characterized as calcareous sublitharenite, litharenite and lithic wacke. Porosity values based on point counting range from 1% to 24%, with highest values in the valley fill and barrier island facies. Porosity is mostly primary although minor dissolution features exist. Cementation (quartz overgrowth and carbonates) is minor throughout, except at the top of the Viking Formation where massive calcite cement completely occludes the porosity. Fluid inclusions in calcite cements are all monophase (liquid-only), indicating relatively low temperatures and early cementation.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005