The present invention relates to a multiphase flow measurement system which can be utilized to determine the individual flow rates of the water, gas, and oil components of a production fluid mixture. The system includes a mass flow measurement means which is coupled to the outlet of the oil well for measuring the total mass flow rate of the production fluid mixture. A vortex shedding device is provided upstream of the mass flow measurement means to transform the production fluid into a homogeneous mixture to increase the accuracy of the mass flow measurement. After the mass flow rate has been determined, a portion of the production fluid is supplied to a test separator tank while the remaining portion is supplied to a production fluid header connected to the outputs of other, unmonitored wells.
The test separator tank is typically a two-phase separator which separates the production fluid into a gas component portion and a liquid portion. A means, such as a net oil computer, is coupled to the liquid outlet of the separator tank to determine the liquid flow rate along with the percentage of oil and water in the liquid portion. A differential/pressure transmitter monitors the gas flow from the gas outlet of the separator tank.
A central control means is responsive to the mass flow measurement, the oil-water percentage, the separator liquid flow rate, and the separator gas flow rate for determining and displaying in BPD units the individual flow rates of the gas, oil, and water components of the production fluid. The use of the mass flow measurement means provides a flow measurement system wherein the entire production output of the well need not be supplied to the separator tank. The individual component flow rates from the test separator tank can be utilized as sample measurements with the total mass flow measurement to obtain individual component flow rates which correspond to total well production. Such a measurement system is especially advantageous for use in off-shore well production wherein the size of the separator tanks is limited.