Effect of pH and API gravity on the water-in-oil emulsion stability

Abstract

Water-in-oil emulsion is serious problems in the industry since it affects oil production negatively and cost huge sum of money to treat. To select a demulsification process for an emulsion problem, it is very important that one should know the condition that favors emulsion stability, once this is established, treatment procedure can be followed to achieve the desire result. In this study, water-in-oil emulsion was formulated with crude samples from various wells (Oredo tank B, Usan and Atala) ensuring they have different API values, their API values are 45, 27.4 and 34 respectively. Also, Usan crude was formulated with water at varying pH of 2.34, 7 and 12.7. The results show that Usan crude with lower API gravity broke out 90ml of oil in 138.5 hours (about six days) while Atala and Oredo broke out 6.0ml and 2.5ml respectively. This shows that the effect of API gravity is directly proportional to the stability. Also, the results collected from the Usan when subjected at varying pH values shows, 65ml of crude was regained from the emulsion when the pH is 2.4(acidic), 35ml of crude was recovered when the emulsion formulated with distilled water with a pH of 7 (neutral) while 14.6ml was recovered when the pH is 12.3 (alkaline). Hence from the conducted experiment it was noted that high pH value favors stability of the oil emulsion, while low pH value is unfavorable for oil emulsion stability.

Keywords: Emulsion; Gravity, pH, Oil, Water