One of the greatest uncertainties in the propagation and dissolution of carbon dioxide upon injection in deep saline aquifers is in the form of rock-fluid properties. The relative permeabilities and capillary pressures of brine, rocks and supercritical carbon dioxide are not well known. The values chosen can have profound impact on the distribution of gas-phase CO2 and dissolved CO2. The concentrations of these species, in turn, affect the reactivity of the rock with brine and carbon dioxide. In this study, we have studied the impact of low-permeability barriers on integrity of CO2 storage. Seals of different permeabilities have been contrasted with reservoirs of varying absolute permeabilities. When these seals are breached, the hydrodynamics of carbon dioxide migration to the top compartments and beyond is governed by the permeability contrast between the parent reservoir and the seals. A phenomenon called “permeability jail” has been observed in the production of gas from tight-gas reservoirs. In this phenomenon, both gas and water are immobile over a substantial saturation range. We have explored the consequences of the existence of permeability jail in carbon dioxide sequestration. A new trapping mechanism named here as “saturation trapping” results due to the existence of permeability jail in the low-permeability seal. The overall distributions of free and dissolved CO2 are analogous to when the entire seal is at lower permeability. The overall distributions are not significantly different when rock/fluid reactions are considered.

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