UN-414: Liquid USM(water cut meter, prover)
Description
Calculates the uncertainty in observed volume, mass and standard volume flowrate for a liquid flow through a USM. USM flowrate uncertainties are determined from an assessment of the meter calibration performance, installation and on-going performance/usage parameters. Line and standard densities and their uncertainties are performed by user-selected density referral calculations. Pressure, temperature, measured density and water cut uncertainties are determined using the technical specification for the transmitters selected from the integrated transmitter selection tool.
General
The General tab is used to enter information, which is saved along with the uncertainty calculation and included in reports which are generated.
The tabs used for inputting data and calculating the uncertainty in the individual components of the uncertainty can be seen along the top of the module window.
The report tab is only visible once the calculation has been run and will not be visible if any parameters are changed until the calculation has been run once more.
Input/Output
Options
Pressure units
This section gives the option of entering the pressure as either an absolute value or as a gauge value with reference to atmospheric (barometric) pressure. If Absolute is selected inputs are required for Absolute pressure and Atmospheric pressure and if Gauge is selected inputs are required for Gauge pressure and Atmospheric pressure. This ensures that whichever is chosen both the gauge and Absolute pressure value is available to other sections of the module.
For example: the Density calculation tab may require an absolute pressure to perform an AGA 8 calculation and the Gauge pressure may be used for the pressure transmitter calculation.
Absolute pressure – the Atmospheric pressure = Gauge pressure
Inputs
Volume flow rate
The volumetric flow rate of liquid stream through the USM.
Temperature
This is the measured temperature of the liquid stream through the USM.
Pressure
This is the line pressure of the liquid passing through the USM.
Note: As described above, if Absolute is selected inputs are required for Absolute and Atmospheric pressure and if Gauge is selected inputs are required for Gauge and Atmospheric pressure.
The default value for Absolute Pressure is set to 1 standard atmosphere (1.01325 bar)
Densitometer temperature
This is the measured temperature from the densitometer.
Density
the density of the liquid flowing through the USM meter.
Water Cut
Percentage of water in the flow.
Outputs
The outputs section shows the calculated flow rate and uncertainty taken from the Liquid Ultrasonic meter tab and Net Oil flow rates tab.
Calculation Blocks
The following blocks are used within this uncertainty module: