Comparison of Completion and Heterogeneity Effect on CO2 Sequestration in Shallow and Deep Saline Aquifers

Abstract

AbstractThe effect of completion techniques and reservoir heterogeneity on CO2 storage and injectivity in saline aquifers has been studied using a compositional reservoir simulator CMG-GEM. Two reservoir models were built using data extracted from publications, to represent a deep saline aquifer and a shallow aquifer. The effect of completion methods, including partial perforation of the reservoir net pay (partial completion), well geometry, orientation, location and length, on CO2 storage are discussed. Heterogeneity effect has been addressed considering three parameters: mean permeability, vertical to horizontal permeability ratio, and permeability variation. Sensitivity analysis was carried out using design of experiments (DOE) to determine the dominant factors affecting CO2 storage capacity and CO2 injectivity. Simulation results show that completing all layers, using horizontal wells set in upper layers with a length around 250–300 m are the most favorable choices for CO2 storage capacity in the aquifer examined. Mean permeability affects CO2 storage capacity and injectivity the most; kv/kh affects CO2 injectivity storage capacity more than permeability variation, Vk. More CO2 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.