Formation-Top Offsets in West Central Alberta, Canada and their Implications for Subsurface Structure

Publication Type
Open File Report
Published Date
Topic
Oil and Gas
Publication ID
OFR 2020-03
Publication ID Extended
Open File Report 2020-03
Publication
Authors
Abstract

Subsurface bedrock formation-top offsets were mapped in west-central Alberta, Canada. The methodology used well-log data and geostatistical analysis to map the offsets. Five stratigraphic horizons were selected for mapping subsurface bedrock offsets; they are in descending order the flooding surface near the top of the First White Speckled Shale (Wapiabi Formation), the base of the Fish Scales Formation, the top of the Wabamun Group, the top of the Graminia Formation, and the ‘Z marker’ in the Ireton Formation. Across the mapped bedrock offset lineaments, consistent elevation differences were observed at the top of the analyzed formations. The selected surfaces represent, or are close to, the marine flooding surfaces in this area that are considered to have been originally close to horizontal and, therefore, are ideal for mapping formation-top offsets. Numerous local offsets were recognized and highlighted using residual maps of these surfaces, and an isochore map of the interval from the base of the Fish Scales Formation to the flooding surface near the top of the First White Speckled Shale. The lineaments detected in the stratigraphic succession were then compared to interpreted/inferred faults from previous publications; the elevation differences across some of the offset lineaments are interpreted as vertical offset across faults. The maps of offsets generated in this report can be used as a starting point for more detailed analyses of potential faults in west-central Alberta.

Citation

Mei, S. (2020): Formation-top offsets in west-central Alberta and their implications for subsurface structure; Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Open File Report 2020-03, 25 p.

Place Keywords
alberta, canada, west central alberta
Place Keywords NTS
83e, 83f, 83g, 83j, 83k, 83l, 83m, 83n, 83o
Theme Keywords
cretaceous, devonian, fault, first white speckled shale formation, fish scales formation, geology, graminia formation, ireton formation, ireton z marker, isopach, lineaments, structures, thrust fault, wabamun group