Investigating the Phase Behavior of Viscoelastic Surfactant with Squalene and Crude Oil Systems at High Temperature

Studying phase behavior at high temperatures is always a challenge due to the risk of evaporation and losing fluid volume; however, we achieved it with our novel device with a high-pressure high-temperature (HPHT) cell, capable of reaching 300 degrees C without losing any fluid volume. Phase behavior has been investigated for viscoelastic surfactant (VES)/crude oil system and VES/squalene system to explore the effect of salinity, concentration, and temperature on the volume fraction phases and the solubilization ratios. The crude oil system is to mimic the real case in the oil field, while the squalene system is considered a reference model oil with known composition and properties. The results showed that in VES/crude oil system, the emulsion volume decreases with increase in salinity and surfactant concentration, while the temperature has a mixed effect on the emulsion volume, which decreased with increase in the temperature to its minimum volume at 90 degrees C and then increased again with increase in the temperature above 90 degrees C. Equal solubilization for each set was achieved at 75% Seawater (SW) salinity, 1.2% VES concentration, and approximately in the temperature range of 60 degrees C to 150 degrees C. In VES/squalene system, the lowest emulsion value was recorded for every set at 50% SW salinity, 90 degrees C temperature, and 1.25% VES concentration. Also, equal solubilization for each set was achieved at 0.5% and 1.25% VES concentration, and 90 degrees C temperature. However, no equal solubilization was noted for the salinity set. In both sets, no lower emulsion phase was noticed, it is either the middle phase or upper phase.

Automated summary

This study investigated the phase behavior of viscoelastic surfactant (VES)/crude oil and VES/squalene systems, and examined the effects of salinity, concentration, and temperature on the volume fraction phases and solubilization ratios. The results showed that in the VES/crude oil system, the emulsion volume decreased with increasing salinity and surfactant concentration, while the temperature had a mixed effect. In the VES/squalene system, the lowest emulsion value was observed at specific salinity, temperature, and VES concentration. Equal solubilization was achieved under certain conditions in both systems.