Visualization of Gas–Oil–Water Flow in Horizontal Pipeline Using Dual-Modality Electrical Tomographic Systems

Abstract

Employing dual-modality tomography inherently involves data from multiple dimensions, and thus a coherent approach is required to fully exploit the information from various dimensions. This paper describes a novel approach for dualmodality electrical resistance and capacitance tomography (ERT-ECT) to visualize gas-oil-water flow in horizontal pipeline. Compared to conventional methods with dual-modality tomographic systems, the approach based on thresholding takes account of multi-dimensional data, which therefore is capable of providing insights into investigated flow in both spatial and temporal terms. The experimental results demonstrate the feasibility of the approach, by which 6 common flow regimes in horizontal pipeline flow are visualized based on the multi-dimensional data with ERT-ECT systems, including (wavy) stratified flow, plug flow, slug flow, annular flow and bubbly flow. Although the present approach is proposed for data acquired with ERT-ECT system, it is potentially adaptable to other dual-modality tomographic systems that use concentration tomograms as inputs.Index Terms-Dual-modality electrical tomography, multiphase flow measurement and visualization, multi-dimensional data fusion, flow regimes visualization.

Capability of dual-modality electrical tomography for gas-oil-water three-phase pipeline flow visualisation

“…An advanced threshold-based data fusion method was developed, which can be applied to these five flow pattern [24]. Since concentration tomograms were obtained with ERT and ECT at different sampling speeds and different grid definitions in the research, they needed to be transformed so that they were spaceand time-aligned before a pixel-by-pixel fusion algorithm performed.…”

“…Finally, pixel values were generated by integrating the threshold values along registered ERT and ECT tomograms. The fusion process is depicted in Figure 6, and the technical detail is described in [24].…”

Dual-Modality 4-Terminal Electrical Capacitance and Resistance Tomography for Multiphase Flow Monitoring

“…In the first category, dual-modality is achieved by the use of two standalone tomography systems. Two independent sensors are placed side to side along a pipe [9][10][11][12][13][14], there are two main drawbacks of this configuration: (1) two standalone acquisition systems and two sensors make the system complex and expensive; (2) In of the second category, there are systems that feature two sets of electrodes in the same plane [15][16], i.e. with an integrated ERT/ECT sensor.…”

Size Projection Algorithm: Optimal Thresholding Value Selection for Image Segmentation of Electrical Impedance Tomography

“…Although many image segmentation algorithms exist [9], such image segmentation is usually performed to categorise pixels into two different classes using a thresholding value. Commonly, a fixed global value based on engineering experience or simulation [10][11][12] is simple and direct for tomographic image thresholding, but its selection is often somewhat arbitrary. For example, Wang et al utilised an empirical value to estimate the central air-core size in a working hydrocyclone [10] and to image large bubbles in flowing water [11].…”

“…Commonly, a fixed global value based on engineering experience or simulation [10][11][12] is simple and direct for tomographic image thresholding, but its selection is often somewhat arbitrary. For example, Wang et al utilised an empirical value to estimate the central air-core size in a working hydrocyclone [10] and to image large bubbles in flowing water [11]. Afterwards, many histogram-based methods [13][14][15] were employed to automatically select the "optimal" thresholding value corresponding to various optimisation measures.…”