When we talk about multi phase flow metering, more likely than not, we mean hydrocarbon multiphase flow measurement i.e. oil, water and gas.
Multiphase flow is actually a misnomer in that the oil and water are both liquid.
A typical Multi-phase flow meter P&ID looks a s below.
Along with multi phase flow meter there is also Well Head monitoring and shutdown control panel.
Generally Multi phase flow meter is used in upstream application at well Heads to determine properties of the Content of the well which has all the phases condensate, water and gasses.
In the oil industry, the main goals expected from the employment of multiphase flow meters are:
(a) to replace test separators,
(b) to avoid installation of test lines and test headers (both in subsea and topside applications) and,
© to improve the well data acquisition (by improving the accuracy and frequency of well tests)
Several physical principles and methods have been applied to multiphase metering concepts, namely:
a) Electrical (impedance, capacitance, inductance);
b) Single or dual energy gamma or X-rays attenuation;
c) Cross correlation velocity (gamma attenuation, microwave, capacitance);
d) Differential pressure (Venturi, mixer device); e) Positive displacement;
f) Pulsed neutron activation (PNA) & Neutron interrogation;
g) Tomography;
h) Partial separation.
In general, a multi phase meter directly or indirectly determines, through its basic instruments, the following properties and parameters:
a) measurement of the mixture velocity and/or of each phase;
b) fraction measurement in each phase;
c) measurement of the mixture density