Curvature-Based Equation of State for Microemulsion-Phase Behavior
KAUST DepartmentAli I. Al-Naimi Petroleum Engineering Research Center (ANPERC)
Energy Resources and Petroleum Engineering
King Abdullah University of Science and Technoloy
Physical Science and Engineering (PSE) Division
Online Publication Date2019-04-11
Print Publication Date2019-04-01
Permanent link to this recordhttp://hdl.handle.net/10754/630251
MetadataShow full item record
AbstractAn accurate description of the microemulsion-phase behavior is critical for many industrial applications, including surfactant flooding in enhanced oil recovery (EOR). Recent phase-behavior models have assumed constant-shaped micelles, typically spherical, using netaverage curvature (NAC), which is not consistent with scattering and microscopy experiments that suggest changes in shapes of the continuous and discontinuous domains. On the basis of the strong evidence of varying micellar shape, principal micellar curves were used recently to model interfacial tensions (IFTs). Huh’s scaling equation (Huh 1979) also was coupled to this IFT model to generate phase-behavior estimates, but without accounting for the micellar shape. \nIn this paper, we present a novel microemulsion-phase-behavior equation of state (EoS) that accounts for changing micellar curvatures under the assumption of a general-prolate spheroidal geometry, instead of through Huh’s equation. This new EoS improves phase-behavior-modeling capabilities and eliminates the use of NAC in favor of a more-physical definition of characteristic length. Our new EoS can be used to fit and predict microemulsion-phase behavior irrespective of IFT-data availability. For the cases considered, the new EoS agrees well with experimental data for scans in both salinity and composition. The model also predicts phase-behavior data for a wide range of temperature and pressure, and it is validated against dynamic scattering experiments to show the physical significance of the approach.
CitationTorrealba VA, Johns RT, Hoteit H (2018) Curvature-Based Equation of State for Microemulsion-Phase Behavior. SPE Journal. Available: http://dx.doi.org/10.2118/194022-pa.
SponsorsThe authors thank the member companies of the Enhanced Oil Recovery JIP in the EMS Energy Institute at Pennsylvania State University for their financial support.
PublisherSociety of Petroleum Engineers (SPE)