Giovanni Grasselli

University of Toronto

The Role of Geomechanics in the Energy Transition

Geomechanics is fundamental to the safe, efficient, and sustainable development of subsurface resources critical to the energy transition, including unconventional hydrocarbons, enhanced geothermal systems (EGS), and geological carbon storage. This presentation summarizes a series of integrated laboratory investigations aimed at advancing the mechanistic understanding of fracture initiation, propagation, and fault reactivation in anisotropic rock formations.

A comprehensive experimental program combining true-triaxial hydraulic fracturing, direct tensile and shear testing, digital image correlation (DIC), and high-resolution fluid pressure monitoring was conducted to evaluate the role of rock fabric and stress conditions. Results highlight the significant influence of bedding planes on fracture geometry and stimulated rock volume, often governing fracture pathways independent of the principal stress orientation.

Complementary fluid injection experiments in pre-fractured, thermally loaded granite specimens demonstrate the coupled effects of fluid pressure and thermal gradients on fault slip behavior. The interplay between injection-induced pressurization and cooling leads to both seismic rupture and aseismic creep, offering insights into permeability evolution and long-term fault stability.

Collectively, these findings underscore the need to incorporate anisotropy, thermal-hydraulic-mechanical (THM) coupling, and fracture-fabric interactions into geomechanical models. Such integration is essential for optimizing the design, monitoring, and risk mitigation of subsurface energy systems supporting the transition to low-carbon technologies.