Systems and Methods for Analyzing Fluid from A Separator

• US 20160091358A1
• Filed: 09/29/2014
• Published: 03/31/2016
• Est. Priority Date: 09/29/2014
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Oddie, Gary Martin, Allouche, Francis, Fraser, Laurence, Jan, Mathilde
• Granted Patent: US 9,778,091 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
• CPC Class Codes: G01F 1/8436 signal processing
• CPC Class Codes: G01F 15/08 Air or gas separators in combination with liquid meters; Liquid separators in combination with gas-meters
• CPC Class Codes: G01F 25/10 of flowmeters
• CPC Class Codes: G01F 25/15 specially adapted for gas meters G01F25/11 - G01F25/14, G01F25/17 take precedence

Abstract

A method for analyzing the reliability of a measured volumetric flow rate of a fluid in a gas outlet line of a gas-liquid separator is provided. In one embodiment, analyzing the reliability of the measured volumetric flow rate includes measuring a gas volume fraction of the fluid in the gas outlet line, comparing the measured gas volume fraction of the fluid to a threshold gas volume fraction level, and determining whether the measured volumetric flow rate of the fluid is reliable based on the comparison. Additional systems, devices, and methods are also disclosed.

Claims

1. A method comprising:

measuring volumetric flow rate of a fluid in a gas outlet line of a gas-liquid separator; and

analyzing reliability of the measured volumetric flow rate of the fluid, wherein analyzing reliability of the measured volumetric flow rate of the fluid includes;

measuring with a sensor a gas volume fraction of the fluid in the gas outlet line of the gas-liquid separator;

comparing the measured gas volume fraction of the fluid in the gas outlet line of the gas-liquid separator to a threshold gas volume fraction level; and

determining whether the measured volumetric flow rate of the fluid is reliable based on the comparison of the measured gas volume fraction of the fluid to the threshold gas volume fraction level.

2. The method of claim 1, wherein determining whether the measured volumetric flow rate of the fluid is reliable includes determining that the measured volumetric flow rate of the fluid is reliable if the measured gas volume fraction of the fluid is above the threshold gas volume fraction level and determining that the measured volumetric flow rate of the fluid is not reliable if the measured gas volume fraction of the fluid is below the threshold gas volume fraction level.

3. The method of claim 1, comprising triggering an alarm if the measured gas volume fraction of the fluid is below the threshold gas volume fraction level.

4. The method of claim 1, comprising automatically adjusting a setting of the gas-liquid separator in response to detecting that the measured gas volume fraction of the fluid is less than the threshold gas volume fraction level.

5. The method of claim 1, wherein measuring volumetric flow rate of the fluid in the gas outlet line includes using the measured gas volume fraction of the fluid in calculating the volumetric flow rate of the fluid.

6. The method of claim 5, comprising selecting the threshold gas volume fraction level.

7. The method of claim 6, wherein selecting the threshold gas volume fraction level includes selecting the threshold gas volume fraction level based on a desired accuracy of the volumetric flow rate measurement, a first margin of error in the measurement of the gas volume fraction, and a second margin of error in the calculation of the volumetric flow rate of the fluid using the measured gas volume fraction.

8. The method of claim 1, wherein measuring the gas volume fraction of the fluid in the gas outlet line of the gas-liquid separator with the sensor includes measuring the gas volume fraction of the fluid with a Coriolis meter.

9. The method of claim 1, wherein measuring the gas volume fraction of the fluid with the sensor includes using a carry-over meter at the gas-liquid separator to measure the gas volume fraction of the fluid.

10. The method of claim 1, wherein measuring the gas volume fraction of the fluid includes:

measuring mass flow rate of the fluid with a Coriolis meter;

calculating an inefficiency factor of the Coriolis meter; and

using the calculated inefficiency factor to estimate the gas volume fraction.

11. An apparatus comprising:

a separator including a gas-liquid separation vessel;

a gas outlet line coupled to receive a gas-containing fluid from the gas-liquid separation vessel;

a Coriolis meter coupled to the gas outlet line to enable measurement of mass flow rate of the gas-containing fluid; and

an analysis system operable to calculate a volumetric flow rate of the gas-containing fluid using the measured mass flow rate, to determine a component volume fraction of the gas-containing fluid, and to use the determined component volume fraction to verify accuracy of the calculated volumetric flow rate.

12. The apparatus of claim 11, wherein the analysis system is operable to use margins of error in the calculated volumetric flow rate and in the determined component volume fraction to verify a desired accuracy of the calculated volumetric flow rate.

13. The apparatus of claim 11, wherein the analysis system is operable to adjust a setting of the separator in response to detecting that a desired accuracy of the calculated volumetric flow rate is not being met.

14. The apparatus of claim 11, wherein the gas-liquid separation vessel is positioned at a wellsite and is coupled to receive produced fluid from wellhead equipment.

15. The apparatus of claim 14, wherein the analysis system is positioned at the wellsite.

16. A method comprising:

routing a multiphase fluid into a separator;

separating the multiphase fluid into a first fluid and a second fluid;

routing the first fluid from the separator into a gas outlet line;

determining a gas volume fraction of the first fluid within the gas outlet line;

measuring a flow rate of the first fluid within the gas outlet line; and

using the determined gas volume fraction to assess quality of the flow rate measurement of the first fluid within the gas outlet line.

17. The method of claim 16, wherein the accuracy of the flow rate measurement of the first fluid within the gas outlet line varies according to the gas volume fraction, and using the determined gas volume fraction to assess quality of the flow rate measurement of the first fluid within the gas outlet line includes comparing the determined gas volume fraction to a threshold gas volume fraction to determine whether the accuracy of the flow rate measurement is above a desired accuracy level.

18. The method of claim 16, wherein determining the gas volume fraction of the first fluid within the gas outlet line includes:

determining an inefficiency factor of a Coriolis meter coupled to the gas outlet line and through which the first fluid is routed;

comparing the determined inefficiency factor to a baseline inefficiency factor; and

determining the gas volume fraction of the first fluid based on the comparison of the determined inefficiency factor to the baseline inefficiency factor.

19. The method of claim 18, wherein determining the inefficiency factor of the Coriolis meter includes calculating a ratio of a drive gain of the Coriolis meter to the square of a pickoff voltage amplitude of the Coriolis meter.

20. The method of claim 18, wherein comparing the determined inefficiency factor to a baseline inefficiency factor includes comparing the determined inefficiency factor to a baseline inefficiency factor calculated for the Coriolis meter for dry gas flow.