Geomechanical Risks Mitigation – A Must for Safe Long-Term CO2 Geological Storage

Carbon dioxide (CO2) capture and geological storage is the best alternative method of produced CO2 disposal instead of venting into the atmosphere. However, there are numerous geomechanical challenges and risks associated with CO2 injection and geological storage that are required to be addressed.

A comprehensive assessment of the geomechanical-related risks to ensure safe CO2 containment and leakage risk mitigation requires coupled geomechanics-dynamic-thermal modelling as part of feasibility evaluation of injecting and storing CO2 in a field. Changes in stresses, mechanical and petrophysical properties based on laboratory CO2-rock interaction test data and deformation state of the rocks are computed by the geomechanical simulator using data from the reservoir simulator which include changes in pressure, CO2 concentration within plume, water saturation and temperature.

The presentation covers the key geomechanical mechanisms associated with CO2 leakage risks and study workflow, and follow by coupled geomechanics-dynamic-thermal modelling assessment of risks associated with CO2-rock interaction, fault re-activation, caprock failure, injected CO2 cooling on caprock and reservoir, and breach of completions and well integrity. The assessments are illustrated through two CCS Storage Development Plan projects for which recommendations from geomechanical perspective were developed. One of the projects is sanctioned for Final Investment Decision with first CO2 injection in 2026.

The take-away insights are geomechanical risk mitigation is one of the key pillars in ensuring safe CO2 geological storage, and the information and workflow presented can be adopted for evaluation of CCS projects in hydrocarbon fields, saline aquifers and dry structures worldwide.