A quantitative study of salinity effect on water diffusion in n-alkane phases: From pore-scale experiments to molecular dynamic simulation

Lifei Yan, Yuanhao Chang*, S. Majid Hassanizadeh, Senbo Xiao, Amir Raoof, Carl Fredrik Berg, Jianying He

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Numerous mechanisms have been proposed to untangle the effect of a low concentration of dissolved salts in the water flooding medium. One potential mechanism for enhanced oil movement is proposed with osmosis effect, however, the process of water transport through the oil phase, due to a salinity contrast, is not fully understood. In our study, we used three aqueous solutions and two alkanes in a series of microfluidic experiments with hydrophobically coated glass micro-chips for mimicking the low-salinity waterflooding process in an oil-wet rock formation. We created multiple systems of low-salinity water-alkane/high-salinity water in the porous micromodel, and afterward, continuously monitored the domain for 70 h. We noted that ionic strength and the hydrocarbon chain length both played important roles in water diffusion. A salinity contrast of 1.7 g/L-170 g/L caused a higher water volumetric flux than 50 g/L-170 g/L for both alkanes. The difference in water volumetric fluxes for those two contrasts were not proportional to the salinity contrast during the experimental period. There was no simple relationship between the chain length of hydrocarbon and water volumetric flux. Moreover, to investigate the effect of salinity on water behavior in heptane, we conducted molecular dynamic (MD) simulations by considering three different concentrations in the high-salinity water region featuring our experiments. The results indicated that high salinity limited the water diffusion from high-salinity phase into the oil phase and reduced the possibility of water entering the heptane phase. Therefore, the net flux of water from the pure water side to the salty waterside was enhanced.

Original languageEnglish
Article number124716
Number of pages15
JournalFuel
Volume324
Issue numberPart B
DOIs
Publication statusPublished - 15 Sept 2022

Bibliographical note

Funding Information:
We would like to acknowledge Wenyu Zhou and Mohammad Hossein Golestan for experimental support with the microfluidics experiments. Author Lifei Yan acknowledges the support from China Scholarship Council (No. 201609120013). This work is financially supported by the Research Council of Norway (Grant No. 234626) and the Chinese Scholarship Council (No. 201908320254). The supercomputer CPU hours were provided by the Norwegian Metacenter for Computational science (Project ID: NN9110K and NN9391K). The third author (SMH) wishes to thank the German Research Foundation (DFG) for supporting this work by funding – EXC2075 – 390740016 under Germany’s Excellence Strategy and acknowledge the support by the Stuttgart Center for Simulation Science (SimTech). Author Carl Fredrik Berg was supported by the Research Council of Norway through its Centers of Excellence funding scheme (project number 262644, PoreLab).

Funding Information:
We would like to acknowledge Wenyu Zhou and Mohammad Hossein Golestan for experimental support with the microfluidics experiments. Author Lifei Yan acknowledges the support from China Scholarship Council (No. 201609120013). This work is financially supported by the Research Council of Norway (Grant No. 234626) and the Chinese Scholarship Council (No. 201908320254). The supercomputer CPU hours were provided by the Norwegian Metacenter for Computational science (Project ID: NN9110K and NN9391K). The third author (SMH) wishes to thank the German Research Foundation (DFG) for supporting this work by funding – EXC2075 – 390740016 under Germany's Excellence Strategy and acknowledge the support by the Stuttgart Center for Simulation Science (SimTech). Author Carl Fredrik Berg was supported by the Research Council of Norway through its Centers of Excellence funding scheme (project number 262644, PoreLab).

Publisher Copyright:
© 2022

Funding

We would like to acknowledge Wenyu Zhou and Mohammad Hossein Golestan for experimental support with the microfluidics experiments. Author Lifei Yan acknowledges the support from China Scholarship Council (No. 201609120013). This work is financially supported by the Research Council of Norway (Grant No. 234626) and the Chinese Scholarship Council (No. 201908320254). The supercomputer CPU hours were provided by the Norwegian Metacenter for Computational science (Project ID: NN9110K and NN9391K). The third author (SMH) wishes to thank the German Research Foundation (DFG) for supporting this work by funding – EXC2075 – 390740016 under Germany’s Excellence Strategy and acknowledge the support by the Stuttgart Center for Simulation Science (SimTech). Author Carl Fredrik Berg was supported by the Research Council of Norway through its Centers of Excellence funding scheme (project number 262644, PoreLab). We would like to acknowledge Wenyu Zhou and Mohammad Hossein Golestan for experimental support with the microfluidics experiments. Author Lifei Yan acknowledges the support from China Scholarship Council (No. 201609120013). This work is financially supported by the Research Council of Norway (Grant No. 234626) and the Chinese Scholarship Council (No. 201908320254). The supercomputer CPU hours were provided by the Norwegian Metacenter for Computational science (Project ID: NN9110K and NN9391K). The third author (SMH) wishes to thank the German Research Foundation (DFG) for supporting this work by funding – EXC2075 – 390740016 under Germany's Excellence Strategy and acknowledge the support by the Stuttgart Center for Simulation Science (SimTech). Author Carl Fredrik Berg was supported by the Research Council of Norway through its Centers of Excellence funding scheme (project number 262644, PoreLab).

Keywords

  • Microfluidic experiments
  • Molecular dynamic simulation
  • Salinity effect
  • Water diffusion
  • Water-alkane interface

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