Anisotropic behavior and mechanical characteristics of the Montney Formation

Abstract

This study investigates the rock mechanics and anisotropic properties of the Montney Formation, Alberta, through two sets of experiments: unconfined compressive strength tests and triaxial compression tests, supplemented by ultrasonic wave velocity measurements. These tests enabled the calculation of dynamic and static stiffness properties and Thomsen anisotropy parameters (ε, δ, γ). Our findings reveal that the Montney Formation exhibits weak anisotropy, with ε values generally below 0.10, contrasting with other strongly anisotropic shale formations. Specimens exhibiting higher clay content and total organic carbon levels show more pronounced anisotropy. Static measurements exhibit a higher degree of anisotropy compared to dynamic measurements. The investigation also explored loading and unloading stiffness parameters, noting a higher E loading-to-unloading ratio for rock specimens with lower elastic properties. This provides important information on the rock's response to stress path effects during stimulation and exploitation. The study also discusses other rock mechanics parameters including Poisson's ratio, tensile strength, and brittleness. The research contributes to a more comprehensive understanding of the geomechanical and petrophysical behavior of the Montney Formation, aiding reservoir characterization and hydrocarbon exploration and production.