RESERVOIR STORAGE AND CONTAINMENT OF GREENHOUSE GASES .2. VAPOR-ENTRYPRESSURES

This paper investigates the role of a nonzero vapour entry pressure on reservoir storage and containment of the greenhouse gas carbon dioxid e. Two effects are observed: vapour storage under confining layers, an d enhanced lateral spreading of gas under confining layers. Lateral fl ow of gas under both impermeable and permeable confining layers is sol ved analytically using Buckley-Leverett assumptions. A full numerical analysis of gas and water transport is also presented, using results f rom the simulator TOUGH. We consider the injection of CO2 from a therm al power plant at a rate of 100 kg/s for 10 years, at a depth of 3000 metres. Inclusion of a nonzero vapour entry pressure shows that contai nment of this gas for at least 5000 years can be expected. The CO2 is stored predominantly in a high density vapour phase (about 600 kg/m(3) ) under lower permeability confining layers, and also is dissolved in liquid at about 40 kg/m(3).