Open File Report 2019-05

Open File Report 2019-05

OFR 2019-05

Three-Dimensional Property Modelling of the Paskapoo, Porcupine Hills, Scollard, and Willow Creek Formations in Southwest Alberta

Author(s) Mei, S. Date 2019-06-14

This report describes the creation of a 3D property model of sandiness/shaliness and porosity for the uppermost Cretaceous–Paleogene bedrock deposits in southwest Alberta. The bedrock units include the Scollard Formation and its equivalent Willow Creek Formation, and the younger Paskapoo Formation and its equivalent Porcupine Hills Formation. These units represent a shale/mudstone-siltstone-sandstone sequence of high energy alluvial and fluvial floodplain sedimentation.

The percentage of shale is inversely related to the sandstone abundance in the sequence and was calculated from a combination of gamma-ray logs from oil and gas wells and lithological descriptions from water wells. The porosity was calculated from bulk density logs from oil and gas wells.

The 3D property model covers an area over 91 000 km2 and represents an eastward-thinning wedge, with a present-day maximum thickness of over 1000 m close to the Foothills of the Canadian Rocky Mountains, that pinches out towards the plains. The model was created in Schlumberger’s Petrel 2015 and is appropriate for regional-scale (1:100 000) assessments rather than site-specific investigations.

The 3D model offers insight into the regional distribution of high-porosity sandstone within the near-surface bedrock deposits. It can be used to conceptualize the hydrostratigraphy, assuming that the sandstone abundance can be used as a proxy for permeability.

Mei, S. (2019): Three-dimensional property modelling of the Scollard, Paskapoo and Porcupine Hills formations in southwest Alberta; Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Open File Report 2019-05, 42 p.