Non-linear seepage law and a characterization model of heavy oil-in-water emulsion in porous media

Abstract

Stable emulsions with different continuous-phase viscosities, dispersed-phase volume fractions, and dispersed droplet sizes were prepared. Seepage experiments using heavy oil-in-water (O/W) emulsion were then conducted in sand packs to analyze the effects of different injection rates, permeabilities, and emulsion characteristics on the seepage law. Finally, an evaluation method for the seepage law was established, and a regression model that considered the factors influencing the non-linear seepage laws was developed using the 1stop software to quantitatively reveal the seepage mechanism. The matching relationship between droplet size and permeability determined the seepage behavior of the O/W emulsion. Emulsions with droplet sizes matched with permeability behaved as a pseudoplastic fluid, with a non-linear flow. With an increase in the dispersed-phase volume fraction, the emulsions displayed a more non-linear behavior due to the accumulated retention and disordered plugging of dispersed droplets. With an increase in the injection rate, the emulsion with a low continuous-phase viscosity had more significant non-linear characteristics than the emulsion with a high continuous-phase viscosity. The correlation of the characterization model was relatively strong under the experimental conditions, with a correlation coefficient of 93.28%. Therefore, the characterization model accurately predicted the effects of the non-linear seepage law for all factors studied.