In　order　to　investigate　characteristics　of　volatile　contaminant　release　and　migration　during　CO2geological　sequestration,　a　contaminant　migration　model　with　multiphase　displacement　process　in　a　CO2-aqueous　phase-residual　oil　phase　system　was　proposed.　Numerical　simulations　were　performed　to　figure　out　the　multiphase　displacement　and　the　contaminant　migration,　and　further　to　explore　the　effects　of　interphase　mass　transfer,　initial　profiles　of　the　residual　oil　and　injection　rates　on　the　volatile　contaminant　migration.　The　results　indicate　that　the　volatile　contaminant　enters　into　the　supercritical　CO2phase　due　to　the　multiphase　displacement　process,　and　migrates　with　the　mobile　phase　in　the　subsurface　formation.　An　interphase　mass　transfer　region　(IMTR)　gradually　forms.　The　evolution　of　IMTR　directly　reflects　the　release　characteristics　of　contaminant　and　migration　behaviors　of　CO2coerced　with　contaminant.　A　larger　interphase　mass　transfer　coefficient　results　in　a　narrower　IMTR　and　a　faster　decay　rate　of　the　oil　phase.　When　the　initial　saturation　of　the　oil　phase　is　larger,　the　IMTR　becomes　much　narrower　and　the　oil　phase　decays　much　slower.　With　increasing　CO2injection　rate,　IMTR　increases　and　the　oil　phase　decays　rapidly.　The　proposed　model　and　the　results　intuitively　describe　the　migration　characteristics　of　the　volatile　contaminants　in　a　variety　of　geological　reservoirs　during　CO2geological　sequestration.　The　proposed　model　can　also　be　used　for　the　risk　analysis　and　evaluations　of　CO2storage.　©　All　right　reserved.