Carbon capture, utilization and storage (CCUS) is a key technology to enable Canada to meet its 2030 GHG emissions reductions targets. While several options exist for the storage element of CCUS; deep, underground geological storage has the largest capacity to store significant quantities of CO2. Key research questions for geological storage (or sequestration) relate to the assessment of the capacity of subsurface formations to receive and safely store CO2 over long periods of time, the technical support for the regulatory frameworks of CCUS and the alleviation of any public concerns about this technology. To address these issues, we are undertaking collaborative research into modeling multiphase flow, heat transport and geomechanical changes that may occur due to CO2 sequestration. In almost all cases, injected CO2 will be at a different temperature than the injection formation, in liquid or gas state at different depths and less dense than the aquifer water so that the injected CO2 may migrate due to density and pressure gradients. Wellbore integrity can also be affected by temperature fluctuations within the near-field environment of the well. It will vary with the heat transferred from the fluids flowing in the well. The heat properties of the materials within and around the wellbore are complicated by:
- Thermally driven advection of the fluids around the wellbore, and
- Complicated pressure/ temperature/ enthalpy relations and phase state of the injected fluid.
The research project is benefitting from active involvement in the Aquistore Project, which is associated with SaskPower's Boundary Dam CO2 Capture Project (Dr. Chalaturnyk), since its inception and the subsurface data being collected from CO2 injection at the CaMI site (Dr. Lawton). These projects are providing unparalleled field data for this research study. The collaborative research project is providing an opportunity to both validate an existing physical model with field data, and to better constrain heat transfer predictions between the wellbore and the near well environment and improve our understanding of various thermal issues related to CO2 sequestration, including injectivity index and downhole injection temperature, phase behaviour, density mixing, changes in formation porosity and permeability, risk of leakage and ground subsurface deformations.