Sensitivity Analyses and Value Qualification of CO2 Storage in the Fractured Saline Aquifer

The objective of this research is to study effects of injection strategies, solubility factor, and aquifer parameters on the feasibility of storing CO2 in the naturally fractured aquifer by running compositional numerical simulator. Factors with direct relevance to CO2 trapping estimations: injection rates, well configurations, permeability anisotropy, fracture locations, fracture permeability, and fracture spacing were investigated using dual-permeability models in compositional reservoir simulator (CMG-GEM). A 30-point experimental design, aimed at evaluating the effect of solubility and aquifer parameters such as depth, porosity, and permeability on CO2 storage, was conducted in various heterogeneous reservoir models. Results show that when horizontal producers are down-dip, the combined influence of buoyancy and heterogeneity can delay CO2 breakthrough. Sub-seismic geological features such as fracture locations, fracture spacing, fracture permeability, and shale layers are demonstrated to have impact on CO2 sequestration. Results are seen to be far more sensitive to thin shale layers than to variations in the vertical to horizontal permeability ratios. The result of the 30-point design shows that variability in trapping efficiency was explained primarily by depth, then permeability, and finally porosity.