Multiphase metering is becoming increasingly important in the development of marginal oil and gas fields. Many of these fields are only economically viable if they can be tied back to existing platform infrastructure, reducing the capital expenditure required by significant margins. In such cases, several fields are often tied back to common facilities requiring each unprocessed stream to be metered before co-mingling. Multiphase metering is also a valuable technology in well management, providing on-line information on the production flow; and in well testing, reducing the capital expenditure required to investigate potential new wells. Wet gas metering is at the high gas fraction end of multiphase metering, typically with a gas volume fraction (GVF) above 90%, and mostly above 95%. Standard multiphase meters cannot operate satisfactorily in such conditions. The development of Wet Gas Meters is therefore a key requirement of the oil and gas industry. There are two principal approaches to wet gas metering. The first is to use a dedicated wet gas meter which has been designed to measure the flow rates of both the liquid and gas phases. The second is to use a standard dry gas meter and apply corrections to the measurements based on knowledge of how the meter in question is affected by the presence of a liquid phase in the gas stream. The second method requires prior knowledge of the liquid flow to correct for the gas flow. Obviously the first method is desirable from the point of view of continuous measurement and well management, however if the liquid flow is known to remain reasonably constant, or change slowly then the second method can be used, subject to a suitable means of determining the liquid flow being available. The work presented in this paper is relevant to both methods. Using the second method with a Venturi meter requires a detailed knowledge of the performance of Venturi meters in wet gas flows. The data contained in this paper offers a significant contribution to this knowledge. The data may also prove useful in the development of commercial Wet Gas Meters based on Venturis.
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