title: Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.
abstract: CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.
authors.affiliation: Environment and Resource System Engineering, Kyoto University , Kyoto, Kyoto 615-8540, Japan.
authors.forename: Hirotatsu
authors.initials: H
authors.lastname: Yamabe
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuji
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Liang
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Matsuoka
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D003198:Computer Simulation; D016062:Porosity; D013500:Surface Tension; D013997:Time Factors; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D002245:Carbon Dioxide