A method for enhancing the storage of carbon dioxide underground. The method comprises locating a geological formation comprising a first storage reservoir having a first surface and a second surface, a first seal layer adjacent the first surface of the first storage reservoir, a second seal layer adjacent the second surface of the first storage reservoir, and a second storage reservoir adjacent the first seal layer opposite the first storage reservoir; directing carbon dioxide into the first storage reservoir, the carbon dioxide being at a first pressure within the first storage reservoir; directing a fluid into the second storage reservoir, the fluid being at a second pressure within the second storage reservoir; and maintaining the second pressure at generally the same or larger pressure than the first pressure of the carbon dioxide to reduce leakage of CO2.