In-Situ Calibration of DP and SONAR Flow Meters for Well Monitoring
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Solution Overview
Problem
The existing DP plus SONAR flow meter system for gas continuous production wells faces inaccuracies in liquid rate measurement due to systematic offsets between differential pressure and SONAR flow meters, requiring in-situ calibration which is limited by the need for dry gas rate consistency, often not met in real production conditions.
Innovation Solution
A method and apparatus for in-situ calibration of the DP plus SONAR flow meter system by measuring dry gas flow characteristics with both meters, determining a dry gas offset, and using this offset to calibrate the system, ensuring accurate liquid rate measurement by aligning the flow meter outputs during the initial dry gas period after a shut-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DP flow meter and SONAR flow meter are used together to measure gas and liquid rates, then the system can utilize differential wetness sensitivity to determine both gas and liquid flow rates, but systematic offsets between the two meters under dry gas conditions cause inaccuracies in liquid rate measurement
Solution Approach 1:
The patent changes the operating condition parameter from general production flow to initial dry gas flow period after shut-in. By selecting a specific time window when the well is producing dry gas, the system can calibrate the offset between DP and SONAR meters under known conditions, thereby improving liquid rate measurement accuracy during subsequent wet gas production.
Solution Approach 2:
The patent performs calibration action before normal production measurement. By determining the dry gas offset during the initial production period after shut-in, the system prepares the measurement system in advance, ensuring accurate liquid rate measurements are possible during later wet gas production phases.
2Measurement precision
If in-situ calibration is performed using well test separator or other methods, then accurate absolute liquid production rates can be determined, but the requirement for dry gas rate consistency between meters limits the utility for many applications
Solution Approach 1:
The patent enables the flow metering system to perform its own calibration using its dual-meter configuration. The DP and SONAR meters measure each other's output during the dry gas period, allowing the system to self-determine the offset without external calibration equipment like well test separators, thereby expanding applicability to fields without such equipment.
Solution Approach 2:
The patent changes the calibration approach from requiring external equipment and dry gas rate consistency to utilizing the initial dry gas flow period inherent in well production cycles. This parameter change makes calibration feasible for a broader range of applications where well test separators are not available.
3Productivity
If DP flow meter is used to monitor gas production, then gas flow rate can be measured, but the meter over-reports gas flow rate in the presence of liquids due to strong correlation with liquid to gas mass ratio
Solution Approach 1:
The patent introduces SONAR flow meter as an intermediary measurement device. The SONAR meter provides an independent measurement of gas flow rate that is not affected by liquid presence. By comparing DP and SONAR readings during the dry gas period, the system can identify and correct DP meter offsets, thereby improving gas flow rate accuracy during wet gas production.
4Measurement precision
If SONAR flow meter is used instead of DP flow meter, then gas flow rate can be accurately reported with less sensitivity to liquid loading, but the system loses the ability to utilize differential wetness sensitivity for liquid rate determination
Solution Approach 1:
The patent merges two different flow measurement technologies (DP and SONAR meters) into a single hybrid system. The SONAR meter provides accurate gas flow rate measurement with insensitivity to liquid loading, while the DP meter provides wetness sensitivity for liquid rate determination. By combining both meters and calibrating their offset during the dry gas period, the system achieves both accurate gas measurement and liquid rate determination capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise calibration and accurate measurement of liquid rates by eliminating offsets between DP and SONAR flow meters, enhancing the reliability of fluid flow monitoring in gas continuous production wells.
Implementation Method 1
measuring a second characteristic of the fluid flow exiting the well using a SONAR flow meter
Implementation Method 2
measuring a first characteristic of the fluid flow exiting the well using a DP flow meter
Data Source
AI summary
A method and system for in situ calibrating a flow metering system to monitor fluid flow in a pipe from a well is provided. The method includes the steps of: a) measuring a first characteristic of the fluid flow exiting the well using a DP flow meter during a dry gas period, and producing an first output data representative of the first characteristic; b) measuring a second characteristic of the fluid flow exiting the well using a SONAR flow meter time during the dry gas period, and producing a second output data representative of the second characteristic; c) determining a dry gas offset between the DP flow meter and the SONAR flow meter based on the first output data and the second output data; and d) calibrating the flow metering system using the dry gas offset.