1 © 2016 IOP Publishing Ltd Printed in the UK 1. Introduction The precipitation of parafin waxes during various phases of production, processing and transportation of waxy crude oil creates challenges to the oil and gas industry and researchers have been interested to investigate the phenomenon of wax deposition under different low conditions, particularly in the subsea pipelines [1–6]. The main motivation behind this research is the rate of formation of wax deposit as it is a critical parameter that has to be taken into account for the design of a much more eficient and cost-effective wax control system [3, 7]. The ideal wax monitoring system should be able to pro- vide real-time and continuous visualization of the actual waxy crude oil low in pipelines so that appropriate wax remediation techniques will be applied when a certain threshold amount of wax has been formed. Many laboratory-scale experimental studies have been performed under both static and low conditions to develop Measurement Science and Technology Real-time monitoring and measurement of wax deposition in pipelines via non-invasive electrical capacitance tomography Irene Lock Sow Mei 1 , Idris Ismail 2 , Areeba Shafquet 2 and Bawadi Abdullah 1 1 Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, 32610 Perak, Malaysia 2 Electrical and Electronics Engineering Department, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, 32610 Perak, Malaysia E-mail: bawadi_abdullah@petronas.com.my Received 24 March 2015, revised 1 November 2015 Accepted for publication 5 November 2015 Published 29 December 2015 Abstract Tomographic analysis of the behavior of waxy crude oil in pipelines is important to permit appropriate corrective actions to be taken to remediate the wax deposit layer before pipelines are entirely plugged. In this study, a non-invasive/non-intrusive electrical capacitance tomography (ECT) system has been applied to provide real-time visualization of the formation of parafin waxes and to measure the amount of wax fraction from the Malay Basin waxy crude oil sample under the static condition. Analogous expressions to estimate the wax fraction of the waxy crude oil across the temperatures range of 30–50 °C was obtained by using Otsu’s and Kuo’s threshold algorithms. Otsu’s method suggested that the wax fraction can be estimated by the correlation coeficient  β = - + - T T T 0.0459 5.3535 200.36 2353.7 3 2 while Kuo’s method provides a similar correlation with  β = - + - T T T 0.0741 8.4915 314.96 3721.2 3 2 . These correlations show good agreements with the results which are obtained from the conventional weighting method. This study suggested that Kuo’s threshold algorithm is more promising when integrated into the ECT system compared to Otsu’s algorithm because the former provides higher accuracy wax fraction measurement results below the wax appearance temperature for waxy crude oil. This study is signiicant because it serves as a preliminary investigation for the application of ECT in the oil and gas industry for online measurement and detection of wax fraction without causing disturbance to the process low. Keywords: image thresholding, wax formation, in situ visualization, tomographic images (Some igures may appear in colour only in the online journal) 0957-0233/16/025403+11$33.00 doi:10.1088/0957-0233/27/2/025403 Meas. Sci. Technol. 27 (2016) 025403 (11pp)