Modelling of Gravity Flows in Porous Media: Implications for the Geological Sequestration of Carbon Dioxide.

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Current global anthropogenic emissions of carbon dioxide are approximately 23 Gigatonnes per year. The influence of the introduction of this large amount of carbon dioxide, a green-house gas, in the atmosphere on future climate has raised huge concerns worldwide. A possible means of reducing the environmental damage is to store the carbon dioxide somewhere until well past the end of the fossil fuel era. Suggestions of storage in ecosystems and at the bottom of the oceans are fraught with difficulties and are very expensive. Storage by direct injection of liquid, or supercritical, carbon dioxide into porous reservoir rocks, such as exist in depleted oil and gas fields and in regional saline aquifers, is being seriously considered. This project aims to identify the rate and form of propagation to be expected. It builds on an initial study of the PIs investigating the axisymmetric flow of liquid input from a point source above an impermeable boundary into a porous medium saturated with liquid of a different density. The current work aims to examine the effects of real situations, which include : a sloping boundary; a slightly permeable boundary; a source of finite size; anisotropy of the porous medium; and different viscosities of the two liquids. Theoretical analyses will be carried out and the results compared with specially conducted laboratory experiments. The new results and understanding will be used to investigate and interpret the current sequestration of carbon dioxide at the Sleipner natural gas field.