Demulsification of Crude Oil-in-Water Emulsions Driven by surfactant

During its production most crude oil occurs as a water-in-oil emulsion whose continuous phase depends on the water to oil ratio, the natural emulsifier systems contained in the oil, and the origin of the emulsion. The emulsifiers are complex chemically and as new oil fields are developed, and as production conditions change in older fields, there is a constant need for new, effective demulsifiers. Demulsification of crude/heavy oil-water emulsion is a major issue that received sustained attention for decades in the petroleum industry. Many strategies including the gravity separation, coalescence technology filtration/membrane separation, absorption, air flotation, coagulation sedimentation, electrolysis process, ultrasonic treatment, and biological treatment etc. have been widely adopted to separate the oil from the O/W emulsions. However, most of the separation technologies are high costly, energy intensive, complex, and time-consuming. Therefore the addition of chemical demulsifiers is the most widely used method. The process is evaluated using some conventional techniques such as interfacial tensiometry, Dynamic Light Scattering (DLS), and bottle test. In this work an amphiphilic material, Cetyl trimethylammonium bromide (CTAB), was introduced as a versatile demulsifier to break up the oil-in-water emulsion at room temperature. It was encouraging to find that the small oil droplets in the emulsion quickly coalesced to form the oil phase and separated with the water within a few minutes. Operating condition was investigated and optimized by studying effect of the CTAB dosage and interfacial tension on the demulsification as an environmental friendly and high efficient demulsifier, CTAB might find its application in separating oil from the O/W emulsion in the petroleum industry.

Keywords:

crude oil , CTAB , surfactant , demulsifier , emulsion