Demulsification of crude oil emulsion by capacitative sensor system measurement: introduction to apparatus and methodology

Standard Bottle Test is often the most common technique to gauge the demulsification performance of a newly formulated crude oil demulsifier. In our work, we have attempted to devise a more specific reliable and reproducible technique for monitoring the demulsification process. It is well-known that as water separates from a crude oil emulsion the capacitance of the mixture changes. By monitoring the change in capacitance at different heights of the emulsion with respect to time using in-house developed capacitance probe, we accurately measure the separation rate and the efficiency of the demulsifier. It was found that substantial changes in the capacitance occurred as the water separates from the emulsion. This method not only has the advantage of being more accurate and robust but can also be adapted to be used directly in the oil field. Here we have used our previously synthesized surfactant Lauramidopropyl glyceryl dimethyl ammonium chloride (LGDMAC) as a demulsifier and its performance has been compared to that of Benzalkonium Chloride. The separation rate and the efficiency were found to be the highest for LGDMAC. Data obtained by the capacitance measurements enabled the determination of the kinetics of the separation rate as well as to quantify the separated water.