Journal article
Modelling low-salinity oil recovery mechanisms using an ion dissociation model
- Abstract:
- Experimental evidence shows that injecting low-salinity water during the oil recovery process can lead to an increase in the amount of oil recovered. Numerous mechanisms have been proposed to explain this effect, and, in recent years, two which have gained notable support are multicomponent ionic exchange (MIE) and pH increase. Both mechanisms involve ion exchange reactions within the thin film of water separating the oil in a reservoir from the clay minerals on the surface of the reservoir rock. Since the reactions occur on the molecular scale, an upscaled model is required in order to accurately determine the dominant mechanism using centimetre-scale experiments. In this paper, we develop the first stages of this upscaling process by modelling the pore-scale motion of an oil slug through a clay pore throat. We use a law-of-mass-action approach to model the exchange reactions occurring on the oil–water and clay–water interfaces in order to derive expressions for the surface charges as functions of the salinity. By balancing the disjoining pressure in the water film with the capillary pressure across the oil–water interface, we derive an expression for the salinity-dependent film thickness. We compare the two mechanisms by modifying an existing model for the velocity of an oil slug through a pore throat. Numerical results show that the velocity increases as the salinity decreases. The percentage increase is larger for the MIE mechanism, suggesting that MIE may be the dominant causal mechanism; however, this will vary depending on the particular clay and oil being studied.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 1.6MB, Terms of use)
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- Publisher copy:
- 10.1007/s11242-018-1220-1
Authors
- Publisher:
- Springer Netherlands
- Journal:
- Transport in Porous Media More from this journal
- Volume:
- 127
- Issue:
- 3
- Pages:
- 685–709
- Publication date:
- 2018-12-26
- Acceptance date:
- 2018-12-10
- DOI:
- EISSN:
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1573-1634
- ISSN:
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0169-3913
- Keywords:
- Pubs id:
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pubs:953249
- UUID:
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uuid:883b447e-8523-4a0c-8aae-1239a104681f
- Local pid:
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pubs:953249
- Source identifiers:
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953249
- Deposit date:
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2018-12-18
Terms of use
- Copyright holder:
- Wilmott et al
- Copyright date:
- 2018
- Notes:
- Copyright © The Authors 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
- Licence:
- CC Attribution (CC BY)
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