Heavy-oil-recovery enhancement with choline chloride/ethylene glycol-based deep eutectic solvent

S. M. Shuwa, B. Y. Jibril*, Y. M. Al-Wahaibi, R. S. Al-Hajri

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


Because of increasing energy demand, unconventional resources such as heavy oil are being explored and recovered. Enhanced-oilrecovery (EOR) methods such as surfactants and polymer flooding must be optimized and new chemicals must be designed to produce more oil. This paper introduces a new deep eutectic solvent (DES) that is based on choline chloride/ethylene glycol for EOR. As preliminary investigations revealed, different concentrations of DES solutions in brine (0 to 100 vol%) were characterized by measuring density, viscosity, conductivity, surface tension, and refractive index at different temperatures (25 to 55°C). Then, the effects of the DES/brine solutions on emulsification with oil phase, wettability alteration, oil/solvent interfacial tension (IFT), formation damage, and tertiary heavy-oil recovery were studied. Potential of the DES solution on enhancing heavy-oil recovery was explored by use of coreflood experiments. This was performed at reservoir condition (pressure = 1,200 psi, temperature = 45 to 80°C) with Berea sandstone core samples and fluids from the field of interest (formation brine and crude oil). An increase in IFT rather than a decrease was observed between the DES/brine solution and the oil. The spontaneous-water-imbibition tests suggested that a decrease in oil-wetness led to an increase in oil production. Approximately 52% of residual oil after waterflooding was recovered with the DES from the coreflooding. The results show an increase in oil recovery with reservoir temperature (6, 13, and 16% on the basis of initial oil in place at 45, 60 and 80°C, respectively). The interaction of the DES with the core materials did not lead to formation damage, as demonstrated by the permeability measurements of the DES/brine solution before and after injection. Viscous forces and wettability alteration were found to be the dominant mechanisms for the tertiary oil-recovery enhancement.

Original languageEnglish
Pages (from-to)79-87
Number of pages9
JournalSPE Journal
Issue number1
Publication statusPublished - Feb 1 2015

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Geotechnical Engineering and Engineering Geology


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