Calibration apparatus and sensitivity determining module for virtual flow meter and associated methods
The present disclosure relates to a calibration device for calibrating a virtual flow meter of a production system. The production system includes components for transferring fluid, where the virtual flow meter is configured to estimate a flow rate of the fluid based on property values of the components and values of variable parameters of the components. The calibration device includes a sensitivity determining module configured to calculate a first sensitivity, where the first sensitivity is used to indicate a degree of change of the values of the variable parameters relative to disturbance of the property values, and a calibration module configured to calibrate the virtual flow meter according to the first sensitivity.
1. A calibration apparatus for calibrating a virtual flow meter for a production system, wherein the production system comprises an element for transferring a fluid, and the virtual flow meter is configured to estimate a flow rate of the fluid based on an attribute value of the element and a value of a variable parameter of the element, the calibration apparatus comprises:
a sensitivity determining module for calculating a first sensitivity indicating an extent of change of the value of the variable parameter with respect to a perturbation of the attribute value;
a calibration module for calibrating the virtual flow meter based on the first sensitivity,
wherein the sensitivity determining module comprises:
a value determination unit for obtaining a plurality of perturbed values based on perturbations imposed on the attribute value according to a perturbation size, and determining a plurality of values of the variable parameter corresponding to the plurality of perturbed values;
a linear regression unit for approximating the plurality of values of the variable parameter by applying a linear regression to obtain an approximated result;
a sensitivity obtaining unit for obtaining the first sensitivity based on the approximated result;
a fitting matching degree calculation unit for calculating a fitting matching degree between the plurality of values of the variable parameter and the approximated result, and outputting the approximated result to the sensitivity obtaining unit when the fitting matching degree belongs to a predetermined range; and
a perturbation size adjusting unit for adjusting the perturbation size when the fitting matching degree does not belong to the predetermined range and outputting the adjusted perturbation size to the value determination unit; and
a sensitivity calculation module for calculating a second sensitivity indicating an extent of change of the flow rate with respect to a perturbation of the value of the variable parameter,
wherein the calibration module obtains, based on the first sensitivity and the second sensitivity, a third sensitivity indicating an extent of change of the flow rate with respect to the perturbation of the attribute value, and calibrates the virtual flow meter based on the third sensitivity.
2. The calibration apparatus of claim 1 , wherein the sensitivity determining module further comprises:
a removal unit for removing an outlier and outputting values of the variable parameter with the outlier removed to the linear regression unit when the outlier is identified in the plurality of values of the variable parameter based on the approximated result, and outputting the approximated result of the linear regression to the sensitivity obtaining unit when the outlier is not identified in the plurality of values of the variable parameter based on the approximated result.
3. The calibration apparatus of claim 1 , wherein the element comprises a pipeline, a valve, a pump, a choke or any combination thereof.
4. The calibration apparatus of claim 1 , wherein the variable parameter comprises a pressure drop of the element, a temperature of the element, or a combination thereof.
5. A calibration method for calibrating a virtual flow meter for a production system, wherein the production system comprises an element for transferring a fluid, the virtual flow meter estimates a flow rate of the fluid based on an attribute value of the element and a value of a variable parameter of the element, the calibration method comprises:
a sensitivity determining step for calculating a first sensitivity indicating an extent of change of the value of the variable parameter with respect to a perturbation of the attribute value;
a calibration step for calibrating the virtual flow meter based on the first sensitivity;
wherein the sensitivity determining step comprises:
obtaining a plurality of perturbed values based on perturbations imposed on the attribute value according to a perturbation size, and determining a plurality of values of the variable parameter corresponding to the plurality of perturbed values;
approximating the plurality of values of the variable parameter by applying a linear regression to obtain an approximated result;
obtaining the first sensitivity based on the approximated result;
calculating a fitting matching degree between the plurality of values of the variable parameter and the approximated result, and outputting the approximated result to the sensitivity obtaining unit when the fitting matching degree belongs to a predetermined range;
adjusting the perturbation size when the fitting matching degree does not belong to the predetermined range and outputting the adjusted perturbation size to the value determination unit;
calculating a second sensitivity indicating an extent of change of the flow rate with respect to a perturbation of the value of the variable parameter;
obtaining, based on the first sensitivity and the second sensitivity, a third sensitivity indicating an extent of change of the flow rate with respect to the perturbation of the attribute value; and
calibrating the virtual flow meter based on the third sensitivity.