A parametric analysis of capillary pressure effects during geologic carbon sequestration in a sandstone reservoir

During carbon capture and sequestration, capillary forces and buoyancy effects strongly influence CO 2 migration and plume geometry. To understand interactions between these processes, we implement a numerical modeling experiment of CO 2 injections in a sandstone reservoir to understand how parametric variability reported in the literature affects numerical predictions of CO 2 migration. We simulate ten years of supercritical CO 2 (scCO 2 ) injections for 189 unique parameter combinations (entry pressure, P o , and van Genuchten fitting parameter, λ ) that control the van Genuchten capillary pressure model. Results are analyzed on the basis of a dimensionless ratio, ω , which is a modified Bond number that defines the relationship between buoyancy pressure and capillary pressure. When ω > 1, buoyancy governs the system and CO 2 plume geometry is governed by upward flow. In contrast, when ω < 1, then buoyancy is smaller than capillary force and lateral flow governs CO 2 plume geometry. We show that the ω ratio is an easily implemented screening tool for qualitative assessment of CO 2 distribution characteristics. We also show how parametric variability affects the relationship between buoyancy and capillary force, and thus controls CO 2 plume geometry: (1) small entry pressure P o encourages vertical flow and large entry pressure P o inhibits vertical flow; and (2) the van Genuchten fitting parameter λ exhibits minimal control on the spatial distribution of CO 2 , as evidenced by the 2 × difference between the ∂ ω /∂ P o and ∂ ω /∂ λ gradients quantified using response surface analysis of the ω ratio. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.