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Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions
Published on: June 6, 2017
Morphological transformations of native petroleum emulsions. I. Viscosity studies
Igor N Evdokimov1, Yaroslav O Efimov, Aleksandr P Losev
1Department of Physics, Gubkin Russian State University of Oil and Gas, Leninsky Prospekt 65, Moscow B-296, GSP-1, 119991, Russia. physexp@gubkin.ru
Langmuir : the ACS Journal of Surfaces and Colloids
|June 20, 2008
Summary
Water-in-oil emulsions exhibit common features across diverse crude oils. Gel structures, not inversion, explain viscosity anomalies, with water separating at high concentrations.
Area of Science:
- Petroleum Engineering
- Colloid and Surface Science
Background:
- Crude oil emulsions are complex mixtures with varying water content.
- Understanding emulsion rheology is crucial for oil recovery and processing.
Purpose of the Study:
- To investigate the morphological features and viscosity behavior of water-in-crude oil emulsions.
- To elucidate the relationship between emulsion structure and rheological properties.
Main Methods:
- Microscopic observation of emulsion morphology.
- Viscosity measurements at varying water volume fractions (φ).
Main Results:
- Emulsions show distinct structural changes with increasing water content.
- Flocculated clusters dominate at low φ; tight gels form at φ ≈ 0.4-0.5.
- Gel domains stabilize larger droplets at higher φ, reaching a close-packing limit of φ ≈ 0.74.
- Above φ ≈ 0.74, water separates as a free phase, not O/W inversion.
- Viscosity decrease at high φ is attributed to stratified flow (W/O gel + free water).
Conclusions:
- The viscosity maximum in W/O emulsions does not indicate inversion.
- Stratified flow, not phase inversion, explains viscosity changes at high water content.
- Emulsion structure dictates rheological behavior, impacting oil production and transport.
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