关键词: 电脱水, 原油乳状液, 短路, pH值

Abstract: The effect of pH on stability of crude oil emulsions was studied. The aggregation and spreading behaviors of resins and asphaltenes on oil-water interface were measured. In addition, the interfacial tension (IFT) and conductivity of model emulsions stabilized by the resin and asphaltene respectively were measured under different pH values. The results indicate that the asphaltenes are easier to aggregate and spread to form high viscoelasticity film than resins. When pH in the acidic range or in the basic range, the IFT both decreases, which enhances the stability and demulsification difficulty of emulsions, and the demulsification experiments are in agreement with it. It has a remarkable change in the stability of resin-stabilized and asphaltene-stabilized emulsions, respectively. When the pH increases from 2 to 10, and their change trends are opposite, pH 2 to 10, the stability of resin-stabilized emulsion increased, the oil-water separation speed slower, the stability of asphaltene-stabilized emulsions decreases, change of the conductivity:0.21—1.8mS/cm. Therefore, when pH < 7, asphaltenes film is strongest, resins film is weakest, the electric dehydrator works normally during the electric dehydration process; however, the results are opposite when pH > 7, all of these demonstrate that the short circuit has a relationship with the change of stability of asphaltenes and resins.

Key words: electric dehydration, crude oil emulsion, short circuit, pH