High-resolution petrophysical, geochemical, and geomechanical profiling of a 230-m continuous core from the Montney Formation, Canada

Low-permeability (tight) siltstones and mudstones of the Mon-tney Formation in western Canada are currently being exploitedwith multistage fractured horizontal wells. A significant chal-lenge for development is effectively targeting zones for lateralplacement and hydraulic fracture stimulation within the typi-cally thick (up to 350 m) gross Montney interval. At the verticalresolution of common well-log suites, the Montney displayslimited variability, with important centimeter-scale changes inpetrophysical and geomechanical properties, which can affectreservoir quality, being undetectable.An unprecedented high-resolution data set consisting of ele-mental compositions (from x-rayfluorescence), permeability(using a profile permeameter), and rock hardness (using a micro-rebound hammer tool) was obtained from a continuous core(230 m) sampling of the entire Montney, as well as small inter-vals of the bounding formations. These nondestructive testswere collected on the slabbed core at 2.5-cm intervals (approxi-mately 10,000 measurement points). Routine core data (poros-ity, permeability, etc.), collected sporadically throughout the210-m interval covering the Montney portion of the core, and aconventional log suite were also available for comparison withthe high-resolution data set.Vertical profiling results demonstrate that the entire Mon-tney Formation (Lower and Middle Members) exhibits signifi-cant centimeter-scale heterogeneity. These members are easilydistinguished with the high-resolution data set, and reservoirquality trends (as quantified with permeability and rock hardness) are similarly easily inferred. As a result, targets forhorizontal lateral placement can be confidently selected. In addi-tion, the high-resolution profiling method proposed herein mayhave important applications for simulating hydraulic fractureheight growth and for selecting appropriate and representativesamples (e.g., core plugs). For the former, low-hardness,organic-rich mudstone beds and weak interfaces with more com-petent rock could act to blunt hydraulic fracture growth. Forthe latter, the centimeter-scale resolution of profiling enablessampling of lithologies for which reservoir properties vary at thecentimeter scale, which is not possible through well-log analysis.