Measurement Characteristics Of Ultrasonic Sensor In Low Fluid Velocity And High Water-Cut Oil-Water Two-Phase Flows

Oil-water two-phase flows widely exist in oil exploitation process. The flowstructure analysis and flow parameter measurements are great significant forimproving oil well production performance and optimizing oil reservoir management.In addition, most of domestic and foreign onshore oil wells are in flow conditions ofhigh water-cut and low fluid velocity, which demands higher requirement for thedetection sensor. Among the methods for measuring multiphase flow, an acousticmethod has the advantage of non-invasive, no fluid corrosion, fitting fornon-transparent and non-conductive fluid medium, which draws attention of manyscholars in the world.In this paper, we carry out the study of ultrasonic detection in high water-cutand low fluid velocity oil-water two-phase flow. We optimize and design two differenttype ultrasonic sensors including embedded patch ultrasonic sensor (EPUS) andprobe-type ultrasonic sensor (PUS) using finite element method. We analyze theirmeasurement characteristics in experiment of oil-water two-phase flow. Theinnovative results we get are as follows:1. We establish the geometry model of EPUS and PUS using the COMSOLsoftware which is based on multi-physics coupling finite element simulation method,and observe the sound and the sensitive field distribution characteristics in20mminner diameter pipe. We extract the average sensitivity (Sa vg) and sensitivity variationparameter (SVP) as the indexes to optimize the size and frequency of ultrasonicsensor. In addition, we establish the model of dispersed flow using finite elementmethod and find that the sound pressure level (SPL) of receiving terminal is sensitiveto individual phase holdup and the bubble diameter.2. We design the embedded patch ultrasonic sensor composed of flexiblepiezoelectric composites and investigate the response characteristics of the embeddedpatch ultrasonic sensor (EPUS) and probe-type ultrasonic sensor (PUS) in oil-watertwo-phase flow experiment, In comparison, we find that the maximum sequence ofultrasonic signal of probe-type ultrasonic sensor shows better measurementcharacteristics and higher resolution of the phase holdup. In addition, the bubblediameter has obvious influence on the response characteristics of ultrasonic sensor, which is quite consistent with the numerical simulation results.