A process for the preparation of a naturally occurring viscous hydrocarbon material, thus obtained emulsions and their preparation as well as detergent compositions for carrying out the treatment

Methods for the formation processing, transportation and end use of a hydrocarbon-in-water emulsion, involving forming a first hydrocarbon-in-water emulsion (e.g. at well head or downhole); degassing it, adjusting its density, breaking the density-adjusted emulsion and re-emulsifying the resulting separated hydrocarbon material, and transporting the resulting second emulsion. Emulsifiers used in the emulsifying steps may comprise non-ionic, cationic and anionic surtactants, polysaccharides, polyacrylamides, cellulose derivatives, xanthan gum, alkalis (e.g. NH404) and water-soluble salts (e.g.of Na, K, Li, Ca, Ba, Mg + Fe).