A nonequilibrium description of alkaline waterflooding
Alkaline waterflooding is complicated because the surfactant species are generated in-situ from acidic components in the crude oil rather than injected externally. The authors previously outlined an equilibrium displacement theory that captured the essential features of the process. Assumption of local equilibrium, however, does not allow for a careful examination of the complex transport and kinetic phenomena that occur. Non-equilibrium theory models the pertinent mass-transfer and kinetic resistances affecting interfacial tensions (IFT's) during displacement of oil-recovery efficiency. The model shows that when natural acid in a trapped oil blob contacts alkali, it diffuses to the interface, adsorbs, reacts with alkali, desorbs, and convects into the bulk aqueous phase. They quantify these transport steps, calculate concentration profiles in the oil and flowing aqueous phases during a linear displacement, and to determine how transient tension behaves as a function of time and distance. Mass transfer resistances are insignificant, but sorption resistances at the oil/water interface affect the transient evolution of IFT during alkaline displacement. Interfacial sorption barriers are modeled with first-order kinetics. Desorption resistances may be quite large, so low IFT's may not be established in typical laboratory-scale cores. Reversible or irreversible surfactant adsorption or reservoir rock is detrimental to alkaline water-flooding. Rock adsorption reduces the amount of surfactant available to the oil/water interface and may raise the IFT to levels that are ineffective in mobilizing residual oil globules. Most importantly, they provide a conceptual framework to design a successful alkaline waterflood.
- Research Organization:
- Univ. of California
- OSTI ID:
- 5512908
- Journal Information:
- SPE (Society of Petroleum Engineers) Reserv. Eng.; (United States), Vol. 1:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CAUSTIC FLOODING
MATHEMATICAL MODELS
OIL WELLS
ADSORPTION
DESORPTION
DISTANCE
ENHANCED RECOVERY
EQUILIBRIUM
MASS TRANSFER
PETROLEUM
QUANTITY RATIO
RESERVOIR ROCK
ROCK-FLUID INTERACTIONS
SURFACE TENSION
SURFACTANTS
TIME DEPENDENCE
WELL STIMULATION
ENERGY SOURCES
FLUID INJECTION
FOSSIL FUELS
FUELS
RECOVERY
SORPTION
STIMULATION
SURFACE PROPERTIES
WATERFLOODING
WELLS
020300* - Petroleum- Drilling & Production