首页|Formulating a model emulsion replicating SAGD in-situ emulsions
Formulating a model emulsion replicating SAGD in-situ emulsions
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NSTL
Emulsions are widely produced and handled in the petroleum industry,particularly in the recovery of heavy oil and bitumen by steam flooding enhanced oil recovery(EOR)techniques.Production of emulsions has been detected from the very early stages of steam-assisted gravity drainage(SAGD)operations,and the literature suggests emulsification occurs in the reservoir.The model fluids employed in the current SAGD sand pack testing,such as sand retention test(SRT)and flow line testing,do not account for emulsions and their properties.This study introduces model emulsions formulated to mimic some essential features of the SAGD in-situ emulsion properties in terms of droplet size,viscosity,kinetic stability,and asphaltene precipitation.Moreover,a workflow is presented which can be used to synthesize model emulsions of any desired properties.Additionally,the effects of gilsonite,sorbitan sesquioleate,oil composition,electrolyte,and water content on the emulsion properties were investigated.It was found that the addition of light n-alkanes with a smaller atomic number in the oil blend results in the formation of emulsions with lower viscosity,weaker kinetic stability,and larger droplet sizes.It was also found that gilsonite which is a rich source of asphaltenes can be used in model emulsions to enhance the emulsions'stability.Molecular dynamic simulation results verified by bottle tests,interfacial tension measurements,and optical microscopy demonstrate that π-π bonding,along with asphaltene-asphaltene and water-asphaltene hydrogen bonding results in face-to-face stacking of asphaltene molecules which in turn leads to the asphaltene aggregation.It was observed that the asphaltene molecules tend to settle at the oil-water interface due to the insolubility of asphaltene in the n-alkane oil and the tendency to associate with water molecules and forming hydrogen bonds.Better kinetic stability was achieved when a blend of non-ionic surfactant was used with gilsonite to prepare emulsions.Moreover,the viscosity of emulsions increased when a larger concentration of gilsonite was used in the emulsion recipes.The electrolyte's presence in the emulsions yielded lower stability.However,a higher dosage of gilsonite dominates the detrimental effect of the NaCl on the emulsion kinetic stability.
NSTL
