| Summary: | This study examines the large-scale variability of porosity and permeability of the sedimentary rocks in the Phanerozoic succession in the Alberta part of the Peace River arch-area of the Western Canada sedimentary basin. The study is based on about 450,000 core analyses at approximately 22,000 wells in an area of more than 165,000 km2. Plug-scale porosity and permeability values are scaled up to the well scale by hydrostratigraphic unit, resulting in two sets of about 16,000 values each for porosity and permeability, unevenly distributed both areally and with depth. The permeability frequency distributions are lognormal for most of the units or parts of the units. The regional-scale variability of porosity and permeability is quite high, between 1 and 38% for porosity, and 0.001 md and 3 d for permeability. The clastic units of the foreland basin exhibit a relatively high correlation between permeability and porosity. Several areal trends and patterns are identified for groups of hydrostratigraphic units, patterns that change gradually from one group to another. It is hypothesized that the observed variability is caused by the dominance of the Peace River arch, carbonate deposition, or compaction at various times throughout the evolution of the basin. Based on the predominant controlling factor, the geological history can be divided into four periods: arch influence during the Early to Middle Devonian, reefal carbonate-deposition influence during the Middle to Late Devonian, passive margin influence during the Late Devonian to Middle Jurassic, and orogenic influence since the Middle Jurassic.
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