The accurate measurement of multiphase flows of oil/water/gas is a critical elementof oil exploration and production. Thus, over the last three decades; the developmentand deployment of in-line multiphase flow metering systems has been a major focusworldwide. Accurate measurement of multiphase flow in the oil and gas industry isdifficult because there is a wide range of flow regimes and multiphase meters do notgenerally perform well under the intermittent slug flow conditions which commonlyoccur in oil production.This thesis investigates the use of Doppler and cross-correlation ultrasonicmeasurements made in different high gas void fraction flow, partially separatedliquid and gas flows, and homogeneous flow and raw slug flow, to assess theaccuracy of measurement in these regimes.This approach has been tested on water/air flows in a 50mm diameter pipe facility.The system employs a partial gas/liquid separation and homogenisation using a T-Yjunction configuration. A combination of ultrasonic measurement techniques wasused to measure flow velocities and conductivity rings to measure the gas fraction. Inthe partially separated regime, ultrasonic cross-correlation and conductivity rings areused to measure the liquid flow-rate. In the homogeneous flow, a clamp-onultrasonic Doppler meter is used to measure the homogeneous velocity and combinedwith conductivity ring measurements to provide measurement of the liquid and gasflow-rates. The slug flow regime measurements employ the raw Doppler shift datafrom the ultrasonic Doppler flowmeter, together with the slug flow closure equationand combined with gas fraction obtained by conductivity rings, to determine theliquid and gas flow-rates.Measurements were made with liquid velocities from 1.0m/s to 2.0m/s with gas voidfractions up to 60%. Using these techniques the accuracies of the liquid flow-ratemeasurement in the partially separated, homogeneous and slug regimes were 10%,10% and 15% respectively. The accuracy of the gas flow-rate in both thehomogeneous and raw slug regimes was 10%. The method offers the possibility offurther improvement in the accuracy by combining measurement from differentregimes.
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