METHOD OF STORING CARBON DIOXIDE IN THE GROUND

PROBLEM TO BE SOLVED: To stably store/isolate undissolved carbon dioxide in an aquifer for a long time, and to greatly reduce the amount of a solvent used therefor.SOLUTION: The mass ratio of undissolved carbon dioxide to be mixed into water saturated with carbon dioxide is determined by the following steps (1) to (3) so that a first storage zone for storing undissolved carbon dioxide together with water saturated with carbon dioxide is formed around the circumference of an injection well in an aquifer and a second storage zone for exclusively storing water saturated with carbon dioxide is roughly concentrically formed in a manner of surrounding the first storage zone in the aquifer respectively, under a condition of storing/isolating water saturated with carbon dioxide as well as undissolved carbon dioxide: (1) a step of measuring the degree of saturation by volume of carbon dioxide, which is defined as the volume ratio of undissolved carbon dioxide storable relative to the volume of the void present in the aquifer, (2) a step of setting the volume of the first storage zone and the volume of the second storage zone, and (3) a step of determining the mass ratio of the undissolved carbon dioxide to be mixed into the water saturated with carbon dioxide based on the degree of saturation by volume of carbon dioxide measured in the step (1), and on the volumes of the first and the second storage zones set in the step (2).