The impact of grid cell size and fluid modeling on CO 2 plume distribution numerical simulation

A central aspect for understanding the CO ₂ geostorage safety in subsurface geological formations is the reliable prediction of the CO ₂ plume spatiotemporal evolution after carbon dioxide injection. This objective is often achieved through detailed numerical fluid flow simulations, and reliable predictions depend on the grid cell size of the reservoir grid and the fluid modeling approach parameterizations. We assess herein the combined impact of grid cell size, reservoir boundaries, and fluid modeling on the trade-offs between computational costs and the numerical simulation accuracy of CO ₂ storage. To reach these objectives, we use a high-resolution three-dimensional reservoir benchmark model from the Illinois Basin Decatur Project. First, we crop and upscale the original high-resolution model. Second, we apply different fluid flow modelling approximations. While model reduction and upscaling result in a decrease of the reservoir porosity and permeability variability, the use of an appropriate fluid flow model can maintain simulation precision under varying grid conditions, highlighting the importance of balancing grid size and resolution with computational demands for reliable CO ₂ storage predictions.