High-Accuracy Wet-Gas Multiphase Well Testing and Production Metering

Abstract

Abstract Dedicated wet-gas flowmeters are now commercially available for the measurement of gas and liquid flow rates. They offer a more compact measurement solution than the traditional separator approach. The interpretation models of traditional multiphase flowmeters emphasize the liquid rate measurements; they have been used to well test and meter mostly liquid-rich flow streams. These models were not developed for the measurement of gas flow rates, particularly those of wet gas. A new interpretation is described that allows a traditional multiphase flowmeter to operate in a dual mode either as a multiphase meter or as a wet-gas meter in 90% to 100% gas. The new interpretation model was developed for a commercially available multiphase flowmeter consisting of a venturi and a dual-energy composition meter. This combination results in excellent predictions of the gas flow rate, and in addition, liquid rate and water-cut predictions are made with an acceptable accuracy with no additional measurements. The wet-gas and low-liquid-volume-fraction interpretation model is described together with the multiphase flow meter. Examples are presented of applying this model to data collected on flow loops, with comparison to reference flow rates. The data from the Sintef and NEL flow loops show an error, better than ± 2% reading for the gas flow rate, at line conditions; the absolute error in the measured total liquid flow rate at line conditions of was better than ± 2 m3/h (< ± 300 bpd). This new interpretation model offers a significant advance in the metering of wet-gas multiphase flows and yields the possibility of high accuracies to meet the needs of gas-well testing and production allocation applications without the use of separators.