Modeling the Effects of Completion Techniques and Formation Heterogeneity on CO₂ Sequestration in Shallow and Deep Saline Aquifers

This work studied the effect of completion techniques and reservoir heterogeneity on CO ₂ storage and injectivity in saline aquifers using a compositional reservoir simulator, CMG-GEM. Two reservoir models were built based on the published data to represent a deep saline aquifer and a shallow aquifer. The effect of various completion conditions on CO ₂ storage was then discussed, including partial perforation of the reservoir net pay (partial completion), well geometry, orientation, location, and length. The heterogeneity effect was addressed by considering three parameters: mean permeability, the vertical to horizontal permeability ratio, and permeability variation. Sensitivity analysis was carried out using iSIGHT software (design of experiments) to determine the dominant factors affecting CO ₂ storage capacity and injectivity. Simulation results show that the most favorable option is the perforation of all layers with horizontal wells 250-300 m long set in the upper layers. Mean permeability has the most effect on CO ₂ storage capacity and injectivity; k _v /k _h affects CO ₂ injectivity storage capacity more than permeability variation, V _k . More CO ₂ can be stored in the heterogeneous reservoirs with low mean permeability; however, high injectivity can be achieved in the uniform reservoirs with high mean permeability.