As the demand for flow measurement of high viscosity and multi-phase is growing globally, operators have been looking for economical and robust flow meter technologies for allocation and control purposes. Despite the wide acceptance of the ultrasonic flow meter technology in single phase flow for fiscal metering and process control (primarily due to the advantage of its wide turn down ratio, no pressure drop etc.), people still remain sceptical about its application on complicated flow with high viscosity liquid or multi-phase conditions. The concern is mostly around the high attenuation of the ultrasonic signals in complex fluid and robustness in noisy environments. This paper describes the study of an ultrasonic liquid custody transfer flow meter in a multiphase flow lab in Aracaju, Brazil where the flow conditions were changed from 0 to 100% water cut of crude oil. Gas volume fraction was varied from 0 to 80%. The purpose of the study was to identify the application boundaries for the liquid flow meter in real applications where water cut can be high and gas carry over is unavoidable. The results showed that the ultrasonic transit time meter could withstand a high percentage water cut and can also tolerate significant amount of gas entrainment. The sophisticated diagnostic feature of the ultrasonic flow meter can even provide some important information regarding the flow regime, which could be beneficial for operators to optimize the operation.
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