Geologic Framework & Reservoir Characterization of the Cardium Formation, Northern Pembina, Alberta, Canada
Wiseman, Andrew; Krause, Federico F.; Debuhr, Chris
The Cardium Formation has been the subject of extensive study since Socony Mobil Oil first struck oil in the Pembina area in 1953. Interest in the formation waned during the 1990's, however, with refinements in horizontal drilling and multistage hydraulic fracing techniques interest has been rekindled. New drilling targets are thinner, lower quality reservoirs that require a greater understanding of subtle variability of reservoir quality and geometry. We use petrophysical, petrological and production analysis techniques to define a geological framework, characterize the reservoir interval, and examine the effectiveness of different completion techniques. Well logs from over 800 wells and core analyses from 440 wells were used to map the formation and identify conglomeratic intervals. Ten cores were logged to characterize lithofacies. Grain size, XRD, EDX and CL analyses were conducted on each lithofacies. New and innovative Variable Pressure Environmental Field Emission Microscopy techniques were developed to identify and observe difficult to image clays and to conduct rock-fluid interaction experiments. Subsurface mapping revealed that only datums below the sandstones provided a realistic basinward dipping geometry, and 3 upwards cleaning sandstone clinoforms were identified. The upper clinoforms have their thickest sandstone intervals in more basinward positions then the underlying clinoforms, indicating basinward progradation. Petrological findings include XRD and BSE identification of kaolinite, illite, and mixed layer kaolinite-montmorillonite clays. Quartz overgrowths have been shown to increase grain size and completely occlude porosity within some sandstone filled burrows. Comparisons between lithofacies and grain size analyses have revealed a clear inverse relationship to water saturation, such that as grain size increases and shale content decreases water saturation also decreases. This relationship holds despite the very slight grain size difference observed between lithofacies.
A total of 126 horizontal wells were used for production analysis. Wells were grouped and compared based on pay thickness, number of fraced stages, and completion fluid. While no positive correlation between pay thickness and production has been observed, there is a strong correlation between completions technology and 1st year production. This is best demonstrated by a 39% increase in 12-months cumulative production in wells with greater than 20 fraced stages.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013