Quantitative Measurement of Two-phase Flow by Electrical Capacitance Tomography Based on 3D Coupling Field Simulation

Measurement of oil-gas two-phase flow parameters such as Gas Void Fraction (GVF) and phase distribution plays a vital role in oil and gas industries. To quantitatively evaluate the performance of Electrical Capacitance Tomography (ECT) for measuring the complex dynamic oil-gas two-phase flows, a three-dimensional fluid dynamics-electrostatic field coupling model (3D-FECM) is proposed in this paper. Coupling simulation are carried out with a 12-electrode ECT sensor. Utilizing the 3D-FECM, the dynamic oil-gas two-phase flows and instantaneous ECT measurements are simultaneously obtained. Two GVF measurement approaches, i.e. the capacitance-based method and the image-based method, are used to calculate GVF. The permittivity distribution is reconstructed by using Linear Back Projection (LBP) and Landweber iteration. The capacitances with signal-noise ratios (SNRs) of 40 and 60 dB are generated for comparison and verification. Evaluation results show that the structural similarity between the ground truth and the reconstructed images using noise-free data by Landweber iteration are better than 0.765, while those by LBP are higher than 0.754, the noise with SNR of 60 dB has no obvious effect on the performance of image reconstruction, and the full-scale error of the image-based GVF prediction using 60 dB noisy data is within -0.82% to +6.09%, slightly better than that of the capacitance-based GVF results (i.e. -1.16% to +7.63%).