A Novel Capacitance-Based Emulsion Monitoring Technology

Abstract

The objective of this paper is to introduce a capacitance-based fixture to assess and monitor crude oil and water emulsion separation kinetics in Gas Oil Separation Plants (GOSPs). The technology provides an online phase separation assessment through dielectric response analysis. The principle of operation of this technology is based on measuring the changes in the capacitance of water/crude oil system versus time as the separation process develops. Free water, emulsion and dry crude oil have different electrical properties, and provide a unique signature to describe the physical composition of the system they form. The evolution of electrical properties of crude oil emulsions at different temperatures, and with or without the addition of chemical demulsifiers is reported. The monitoring tool consists of a cylindrical fixture where the emulsion electrical properties are monitored during the phase separation. The fixture is connected to an Inductance Capacitance Resistance meter (LCR) to measure the change in electrical impedance of the emulsion. The fixture has a cylindrical geometry and its design was adapted to discretize the phase distribution of complex fluid mixtures. The fixture electrical properties were estimated based on its shape and material of construction, and verified by measuring the electrical impedance of fluids of known dielectric properties. The technology was tested under different conditions of temperature and concentration of demulsifier and was able to measure accurately the sample water cut and to monitor water separation kinetics in real time. The results are driving the development of an online emulsion stability assessment tool to characterize emulsion separation kinetics at process conditions. In addition, this tool will improve the accuracy of emulsion separation measurements in crude oil processing facilities by avoiding emulsion alteration due to degassing, shearing and aging inherent to bottle test procedure.