| Popis: |
Carbon dioxide (CO2) capture and geological storage is one of the best alternative methods of produced CO2 disposal rather than venting it into the atmosphere. However, there are numerous geomechanical challenges and risks associated with CO2 injection and geological storage that are required to be addressed. The key challenges include delineating the geological seal barrier and maintaining the seal integrity throughout the injection operation and storage life. The assessment of geomechanical-related challenges and risks to manage CO2 containment and mitigate leakage risks require a coupled geomechanical study that needs to be conducted as part of feasibility evaluation of injecting and storing CO2 in a field. In the geomechanics-dynamic coupled modelling, at selected stress steps the reservoir model passed data including pressure, CO2 concentration within the plume, water saturation and temperature to the geomechanical model. Changes in stresses, rock mechanical and rock petrophysical properties based on laboratory CO2-rock interaction test data, displacements, strains and deformations were computed by the geomechanical model using the data from the reservoir model. Updated petrophysical properties such as permeability and porosity were passed by geomechanical model back to the reservoir model and used in the next dynamic simulation step. The coupled geomechanical modelling assessed CO2 leakage risk associated with fault re-activation, failure of cap rock, CO2-rock interaction, and cooling of injected CO2 on caprock and reservoir rock. Axial loading on completions due to reservoir compaction could cause buckling collapse and/or cement failure. Fault re-activation was based on induced fault plastic shear strain throughout the injection programme which may pose risk of CO2 leakage. The evaluation of induced plastic shear strain and failure state of caprock, effect of CO2 interaction and cooling on the caprock and reservoir rock integrity, and compaction and associated subsidence were also evaluated. Recommendations from geomechanical perspective can subsequently be developed from the results and findings for the CO2 injection programme and storage operation. |
