The pore-scale mechanism of diluted bitumen displacement using microchips and a high magnification imaging system is reported. The influence of the injected chemical solutions on the heavy oil mobilization and the oil film detachment from solid surfaces is investigated. The injected aqueous phase fingers through the viscous oil leaving a considerable oil behind which is detached and emulsified as the injection continues. The thickness of remaining oil and the intensity of emulsification depend upon the properties of the injected chemicals. The incremental oil mobilization is directly related to the thickness of the remaining oil films and the efficiency of chemicals to carry the detached oil blobs. Surfactants are effective in facilitating the oil film de-wetting and reducing the interfacial tension that promotes emulsification.