Abstract
An ideal multiphase flow meter should have the majority of these characteristics:
1. Measure the void fraction of the dispersed phase within the continuous phase
2. Determine the flow regime of the mixture flow
3. Measure the flow rate of each phase (preferably in terms of superficial velocities)
4. Perform non-intrusive measurements where the mixture flow is unaltered by redirection, reduction in flow area, or obstruction
5. Have wide range of applicability with respect to types of fluids, flow rates, flow regimes, conduit size, temperatures, and pressures
6. Produce consistent measurements over a long period of time
7. Be simple and inexpensive.
Evidently, such a meter does not exist yet. However, the need to perform such measurements for the nuclear, chemical, and oil industries (to name a few) has led to substantial development of instruments that bear some resemblance to the ideal meter whose characteristics are mentioned above. Some of the instruments used in the field of multiphase metering are the gamma densitometer, the impedance meter, the magnetic flow meter, the positive displacement meter, the ultrasonic sensor, the auto-correlation sensor, the microwave watercut meter, and the pressure transducer, in addition to flow visualization techniques.
A modern multiphase flow meter usually includes several of the above-mentioned instruments. The measured quantity, the nature of the application, and the field environment are the most important parameters considered while designing and/or selecting the most appropriate combination of instruments. There are currently several hundred multiphase flow meter installations around the world. The technical advances in the majority of these meters are providing valuable information to the operators, not only to measure flow rates but also to optimize production [I].
An assessment of the various technologies employed in most of the commercial multiphase flow meters is provided in this paper. A brief description of the various multiphase metering technologies along with their advantages and disadvantages are presented.