Effect of Clay Type on Emulsion Formation in Steam and Solvent Steamflooding

The objectives of this study are to perform a fundamental analysis of the mutual interactions between crude oil components, water, hydrocarbon solvents, and clays, and to determine the optimum hydrocarbon solvent in solvent steamflooding for a particular reservoir type. The water/oil emulsion formation mechanism in the obtained oil for steam and solvent steamflooding processes has been studied via intermolecular associations between asphaltenes, water, and migrated clay particles. A series of 21 steam and solvent-steamflooding experiments has been conducted, first without any clays in the oil/sand packing, and then using two different clay types in the reservoir rock: Clay 1, which is kaolinite, and Clay 2, which is a mixture of kaolinite and illite. Paraffinic (propane, n-butane, n-pentane, n-hexane, n-heptane) and aromatic (toluene) solvents are coinjected with steam. Cumulative oil recovery is found to decrease in the following order: no clay, Clay 1, Clay 2. Based on the obtained produced oil analyses, Clay 1 and Clay 2 are found to have an affinity with the water and oil phases, respectively. Moreover, the biwettable nature of Clay 2 makes it dispersed in the oil phase toward the oil/water interface, stabilizing the water/oil emulsions. Paraffinic solvent n-hexane is found to be an optimum coinjector for solvent steamflooding in bitumen recovery.

Automated summary

This study aims to analyze the interactions between crude oil components, water, hydrocarbon solvents, and clays, and identify the optimum hydrocarbon solvent for solvent steamflooding in a specific reservoir type. The experiments showed that Clays 1 and 2 have different affinities with water and oil phases, affecting the stability of water/oil emulsions during solvent steamflooding. Additionally, n-hexane is found to be the optimal coinjector for bitumen recovery in solvent steamflooding.