Another area of research is the development of CO2 injection techniques that achieve broad dispersion of CO2 throughout the formation, overcome low diffusion rates, and avoid fracturing the cap rock. Site characterization and injection techniques are interrelated because improved formation characterization will help determine the best injection procedure.
Saline formations tend to have a lower permeability than do hydrocarbon-bearing formations, and work is directed at hydraulic fracturing and other field practices to increase injectivity. Saline formations contain minerals that could react with injected CO2 to form solid carbonates. The carbonate reactions have the potential to be both a positive and a negative. They can increase permanence but they also may plug up the formation in the immediate vicinity of an injection well. Researchers seek injection techniques that promote advantageous mineralization reactions.
Researchers, regulators, geologists and engineers understand that storage sites must be selected, designed and installed very carefully to ensure drinking water is protected. The injection wells consist of multiple layers of steel and cement to protect the shallow water aquifer and residential water wells.