Wax appearance temperature in crude oils measured by surface plasmon resonance

Abstract

To predict and quantify the wax appearance temperature in crude oils, we proposed and implemented a well-explored sensing method known as surface plasmon resonance. This phenomenon occurs when an incident light beam couples into a metallic surface. As sensing method, this phenomenon has been widely used in biosensing applications. In this research, we showed the effectiveness of the surface plasmon resonance sensing technique in hydrocarbon sensing in general and in crude oil wax appearance prediction in particular. To the authors knowledge, this is the first exploration of monitoring wax deposition events from crude oil using surface plasmon resonance measurements. A compact optical sensor was developed from an ultra-thin layer of gold deposited on a sapphire prism and supported by a new data analyzing metric to analyze the acquired reflected beam intensity profile and detect the precipitation of crude oil wax or other hydrocarbon particles under varying-temperature and low-pressure conditions. The obtained wax appearance temperatures using the introduced on-site method were found to be comparable with the literature measurements using the common in-lab Cross-Polarization Microscopy method.