Emulsion type and stability are directly linked to the physicochemical formulation, which controls the interfacial interactions of the surfactant with the oil and water phases. During petroleum production processes, emulsions have to be stabilized, broken., or inverted and the formulation has to be adjusted to attain the required property. This is, in particular, the way to reach a proper rheology that insures the flow. lithe formulation is not controlled, unwelcome changes, such as phase inversion, can take place and plug the porous medium or the pipeline through which a multiphase system is transported. Three specific cases still under development are discussed as critically depending upon formulation: displacement in porous medium during surfactant flooding for enhanced oil recovery, heavy crude oil emulsified transport in the pipeline, and control of the gas hydrate slurry in deep subsea transportation.