THE EFFECT OF WATER CONTENT, pH, SALINITY AND TEMPERATURE ON THE STABILITY AND SURFACE TENSION OF RUSSIAN URALS CRUDE OIL EMULSION

Abstract

The effect of pH, salinity and temperature on stability and surface tension of Russian Urals crude oil-water emulsions were investigated. Emulsions were prepared by mixing distilled water and Russian crude oil (1/3) volume ratio with three different buffered solutions of pH 2.00, 4.00 and 7.00. The stability of the emulsions and their surface tension were measured. Five aqueous solutions of NaCl (concentrations 0.570, 1.407, 1.711, 3.080 and 4.106 mol/l, respectively) were mixed with the crude oil and volume fraction 1/4 (water/oil) to make emulsions, another five aqueous solutions for the crude oil (1.50g, 2.50g, 3.50g, 4.50g and 5.50g of NaCl) were prepared. Surface tension of the emulsions and that of the crude oil and stability of emulsions were measured. In order to avoid distillation of the light components from our close measuring vessel, temperatures 20.01, 25.05, 29.01, 31.50 and 35.05 °C were applied. Surface tension of crude oil and that of an emulsion of 3/1 (oil/water) volume fraction were measured. Surface tensions of crude oil, and emulsion decrease as the temperature increases, but the surface tension of crude oil and emulsion increased as the salinity (concentration NaCl) as well as the pH value in the range (from 2.00 to 7.00) increases. On the other hand, the results of emulsions stability show that the stability of emulsions decreases both with increasing temperature and (NaCl) salt concentration, also, as the water fraction increases, the emulsion stability decreases. For pH, it was found that there is unstable emulsion formed at pH=7.00 and a very stable emulsion formed at pH = 2.00.