Modelling the Dynamic Behaviour of Structural Traps for Carbon Sequestration

                                                 

Abstract. Geological structures play a critical role in carbon dioxide (CO₂) sequestration, providing natural barriers and spaces to trap CO₂ securely in subsurface formations. Modelling the dynamic behaviour of structural traps gives valuable insights into carbon dioxide (CO₂) storage capacity and plume evolution. This helps identify the optimal injection strategies, understand the effect of CO₂ plume migration, and predict the long-term containment of CO₂. This study analyses the effect of cap rock architecture in the CO₂ plume migration and estimates the CO₂ trapping capacity for different geological structures. Using the MATLAB Reservoir Simulation Toolbox (MRST-co2lab), theoretical models comprising anticlines and anticlines with varying dips were used to simulate CO₂ injection and migration using the spill point analysis. For the study, a three-dimensional corner point grid was constructed to represent structural features over an area of 60 square kilometres. The model incorporates a porosity range between 7% and 35%. The results from spill-point analysis indicate that the anticline structures with a dipping angle of 0.3 degrees and 0.4 degrees exhibit a capacity of 55.87% and 22.36% compared to the anticline structure without any dip. It was observed that the plume direction was oriented towards the top of the dipping direction. That is, the fluid migration is along the slope of the dip. The findings emphasise that a steeper dip results in lower storage capacity due to faster plume migration and reduced CO₂ trapping. These results highlight the variability in percentages of the CO₂ trapping efficiency and emphasise the importance of both geological structure and fluid properties in determining storage capacity. The insights obtained from spill point analysis can contribute to better planning and optimisation of carbon sequestration strategies by highlighting the influence of cap rock architecture on storage potential.

Keywords: Geological carbon sequestration; CO₂ trapping mechanisms; Spill point analysis