The use of a low-cost gas-liquid flow meter to monitor severe slugging

A very simple, low-cost gas-liquid flow meter that only employs conventional field instrumentation has been used to monitor severe slugging occurring at the exit of a vertical pipe. This meter was originally developed for conventional oil field applications [1] and is based on the readings of a multiphase orifice and the pressure drops of the gas-liquid mixture flowing in a vertical section of the pipe. Liquid and gas flow rates have been determined by means of semi-empirical equations developed for the specific set of flow parameters (geometry, flow rates, physical properties) adopted in a series of laboratory tests conducted in the Multiphase Flow Laboratory of TEA Sistemi. The transient behavior of the flow system, including the orifice, has also been predicted by means of a 1-D flow simulator [2]. The results of these simulations agree well with the experimental readings, thus providing a powerful method to monitor severe slugging by means of low cost instrumentation, in particular, by replacing a cumbersome instrument such as a gamma-densitometer with a differential pressure transmitter. In field operation, the multiphase orifice used in these experiments can be replaced by a calibrated control valve.