TY - JOUR

T1 - Comparability of in situ crude oil emulsification in phase equilibrium and under porous-media-flow conditions

AU - Borji, Mostafa

AU - Kharrat, Ahmad

AU - Ott, Holger

N1 - Publisher Copyright: © 2022 The Authors

PY - 2022/6

Y1 - 2022/6

N2 - HypothesisThe emulsification of water and crude oil is typically examined and optimized in test tubes by optical means, that is, mixed under turbulent conditions and detected outside the porous medium in equilibrium. In this study, we investigate the rather complex case of crude oil emulsification by alkaline solutions to assess whether the classical phase behavior experiments are representative of the emulsification under laminar flow conditions in porous media.ExperimentsWe characterized the phase equilibrium in the test tubes through X-ray attenuation in micro-X-ray computed tomography (μCT). Moreover, we showed that for these systems, the conventional qualitative optical inspection leads to considerable misinterpretation. X-ray attenuation ensures a quantitative analysis directly comparable to results from μCT-based core-flood experiments, where phase mixing occurs in porous media flow. The study was complemented with microfluidic experiments providing additional high-resolution information on emulsion phases.FindingsWe conclusively show that in the complex in situ saponification of crude oil by alkaline flooding, (a) the emulsifications in test tubes and in porous media flow are comparable, considering the displacement process in the latter; (b) a minimum emulsion volume with balanced compositions leads to optimal oil recovery in μCT-based and conventional core flooding and in microfluidics.

AB - HypothesisThe emulsification of water and crude oil is typically examined and optimized in test tubes by optical means, that is, mixed under turbulent conditions and detected outside the porous medium in equilibrium. In this study, we investigate the rather complex case of crude oil emulsification by alkaline solutions to assess whether the classical phase behavior experiments are representative of the emulsification under laminar flow conditions in porous media.ExperimentsWe characterized the phase equilibrium in the test tubes through X-ray attenuation in micro-X-ray computed tomography (μCT). Moreover, we showed that for these systems, the conventional qualitative optical inspection leads to considerable misinterpretation. X-ray attenuation ensures a quantitative analysis directly comparable to results from μCT-based core-flood experiments, where phase mixing occurs in porous media flow. The study was complemented with microfluidic experiments providing additional high-resolution information on emulsion phases.FindingsWe conclusively show that in the complex in situ saponification of crude oil by alkaline flooding, (a) the emulsifications in test tubes and in porous media flow are comparable, considering the displacement process in the latter; (b) a minimum emulsion volume with balanced compositions leads to optimal oil recovery in μCT-based and conventional core flooding and in microfluidics.

UR - http://www.scopus.com/inward/record.url?scp=85124021695&partnerID=8YFLogxK

U2 - 10.1016/j.jcis.2022.01.182

DO - 10.1016/j.jcis.2022.01.182

M3 - Article

VL - 615.2022

SP - 196

EP - 205

JO - Journal of colloid and interface science

JF - Journal of colloid and interface science

SN - 0021-9797

IS - June

ER -