基于复阻抗法的水平井流体持率测量初步研究OA

To overcome the limitations of the current electrical method in measuring the fluid holdup in horizontal wells,such as the single measurement parameter and the complex structure of the measurement device,a new method for measuring the fluid holdup in horizontal wells based on the complex impedance method is proposed,and its feasibility is systematically studied.The complex impedance spectrum method is adopted as the measurement principle,and a 2N sequence pseudo-random signal is used as the multi-frequency synchronous excitation source.Through a combination of theoretical analysis and numerical simulation,the theoretical basis of the complex impedance method for holdup measurement is deeply explored.The COMSOL finite element simulation software is used to conduct forward research and obtain the complex impedance spectrum response characteristics of oil-water two-phase flow stratified flow under different holdup conditions.The real part ratio and the imaginary part slope ratio of the complex impedance are extracted from the spectrum data as key dimensionless characteristic parameters reflecting the water holdup.The radial basis function(RBF)neural network is introduced to establish a nonlinear inversion fitting model between the characteristic parameters and the water holdup.A preliminary design of the fluid holdup measurement system based on the complex impedance method is carried out,and indoor simulation experiments of oil-water two-phase flow stratified flow are conducted to verify the actual measurement feasibility of this method.The research results show that:①The complex impedance spectrum of oil-water two-phase flow can effectively reflect its holdup information,and the extracted real part ratio and imaginary part slope ratio characteristic parameters have a significant nonlinear mapping relationship with the water holdup,which can effectively eliminate the influence of different salinity water on the measurement results.②Compared with the polynomial fitting method,the RBF neural network shows better nonlinear approximation ability in the inversion of water holdup,with the sum of squared errors reduced by 93.7%,the coefficient of determination R2 reaching 0.999 9,and the root mean square error being only 0.113 2,significantly improving the prediction accuracy.③Under the indoor simulation experiment conditions,the recognition results of the designed measurement system for oil-water two-phase flow with different water holdups are basically consistent with the actual water holdup,and the average coincidence rate of oil-water identification in stratified flow is greater than 90%,with the maximum relative error being 12%.The conclusion is that the complex impedance method for measuring the fluid holdup in horizontal wells is feasible in theory.The preliminary designed measurement system based on the complex impedance method can effectively identify the water holdup in the fluid,verifying the practical application potential of the complex impedance method in the field of holdup measurement in horizontal wells,and laying a theoretical foundation for the subsequent development of complex impedance holdup measurement technology under multi-flow patterns and complex working conditions.