Novel method for measuring small water holdup in oil production pipeline

Abstract

Recent cost effective electromagnetic (EM) tools are becoming more and more promising in the field of petrochemical industry for logging, metering, and early water detections. In this thesis, a novel microwave technique is proposed to determine the water holdups in a horizontal or near horizontal petroleum production pipeline. The propagation of EM waves in such a pipeline is governed by the geometrical and electrical properties of the pipe and its contents. For a pipeline carrying two-phase fluids (water and oil), a change in the percentage of different liquids will modify the effective dielectric constant of the system and in return influences the cutoff and modal characteristics of the propagating waves. The cutoff behavior of a two-port network, consisting of an aluminum pipeline of diameter 43.78 mm and two coaxial probes (SMA), are analyzed here to determine the water level in the pipe. The termination of the pipeline section and setting of the probes are carefully selected to minimize the affects of the backward and higher- order modes. A finite element based package is used to simulate and optimize the S-parameter responses of the designed system. Although the simulated response correctly predicted the water level up to 23% of the pipeline diameter, the essence of this approach is its ability to accurately measure very small water holdup in the pipeline (< 5%). The designed device was fabricated to verify the predicted results. The experimental results, observed using a vector network analyzer, agreed well with the simulated reflection and transmission responses.