Effect of solvent type on emulsion formation in steam and solvent-steam flooding processes for heavy oil recovery

In this study, a series of steam and solvent-steam flooding experiments are conducted to study the produced oil quality in terms of water-oil emulsions. A set of seven experiments are performed, beginning with steam flooding, and solvent-steam flooding using propane, n-butane, n-pentane, n-hexane, and n-heptane as paraffinic solvents that are insoluble in asphaltenes, and toluene, which is a polar solvent soluble in asphaltenes. Co-injection of solvents along with steam improves the cumulative oil recovery and produced oil quality by promoting less water migration into the bulk oil phase, hence reducing water-asphaltenes polar interactions. Asphaltene content in the produced oil and the displaced residual oil is found to generally increase with increasing carbon number of paraffinic solvent. Hexane is found to be the most effective hydrocarbon solvent in solvent-steam flooding for bitumen recovery, with optimum amount of asphaltene content and dispersion in produced oil, and minimum amount of water trapped in the oil phase, hence alleviating emulsion complexity. This is a first attempt to assess the efficiency of a wide range of solvent-steam flooding performances in terms of obtained oil emulsion quality, which will be very influential for field applications in selecting a solvent for a particular reservoir.