Effects of temperature and time on interfacial tension behavior between heavy oils and alkaline solutions

Abstract

Heavy oils contain significantly more acidic components than conventional crude oils. Upon contact with aqueous alkaline solutions, water‐soluble surfactants are formed in‐situ at the interface. These surfactants have the ability to reduce the oil/water interfacial tension to ultra‐low values. This work studies the significant effects of time and temperature on the interfacial tension between alkaline solutions and two Canadian heavy oils (Lloydminster and Cold Lake). The results obtained indicate that the time period during which interfacial tension remains ultra‐low is just as important as the magnitude of the minimum attainable interfacial tension in determining the potential success of an alkaline flooding process in the field.

Bitumen-in-Water Emulsions Stabilized with Natural Surfactants

“…Equation [3], which assumes that the double-layer potential remains constant during the approach, provides a good estimate of the repulsive potential energy. Overbeek (28) has shown that the linear approximation assumed by Hogg et al (27) is remarkably good, even at a surface potential of 100 mV.…”

“…[3], it is necessary to determine the electrostatic potential ψ s and the Debye parameter κ. Several investigators (29,30) have suggested that the zeta potential (ζ ), determined by electrophoretic measurements, is approximately equal to the interfacial potential, ψ s .…”

“…Thus, the values of the zeta potential, determined for our bitumen-in-water emulsions, were used in place of ψ s in Eq. [3]. The values of κ were calculated using the expression…”

“…When such acidic crude oils are contacted by alkaline water solutions, surface-active soaps are formed at the interface due to the reaction between the carboxylic acids present in crude oil and the alkaline species in the aqueous phase (3). Due to its importance in several of the processes, normally carried out in the petroleum industry, specially in crude oil production, treatment, and transportation, these native tensoactive compounds, referred to here as natural surfactants (NS), have been the subject of many studies.…”

A dynamic model for the interaction of caustic reagents with acidic oils

“…When these surface active anions accumulate sufficiently at the oil/ water interface, the IFT may be drastically lowered. Several researchers (Jennings, 1975;McCaffery, 1976;Trujillo, 1983;Babu et al, 1984) have observed the dynamic nature of the IFT which arises in caustic-acidic crude systems. The IFT has also been shown to vary with crude oil type, reservoir salinity, and the alkalinity of the floodwater.…”