Multiphase Flow Rate Determination Using Constriction Pressure Differential
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Solution Overview
Problem
Conventional multiphase flow meters are expensive, making them unsuitable for low hydrocarbon producers, such as 'brown' field sites with reduced capacity, where determining gas and liquid flow rates is crucial but cost-effective solutions are needed.
Innovation Solution
A method and apparatus utilizing a conduit with a constriction to measure differential static pressure in the gas core and differential liquid layer pressure, correlating gas and liquid flow rates, allowing for the determination of both flow rates through measurements of pressure and optional additional quantities like liquid layer thickness and axial velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multiphase flow meters are used, then accurate flow rate determination is achieved, but the cost becomes prohibitively high for low hydrocarbon producers
Solution Approach 1:
The patent segments the measurement task into two separate measurements: differential gas core static pressure and differential liquid layer pressure. Each measurement targets one phase, allowing independent determination of gas and liquid flow rates. This segmentation simplifies the overall measurement system compared to conventional multiphase meters that measure all phases simultaneously with complex sensor arrays.
Solution Approach 2:
The patent introduces a constriction element as an intermediary component that creates the pressure differential measurements. The constriction generates a known pressure drop that correlates with flow rates, serving as a mediator between the flowing phases and the measurement system. This intermediary structure enables flow rate determination through simple pressure measurements rather than direct phase measurement.
2Reliability
If conventional multiphase flow meters are deployed, then reliable flow measurement is obtained, but the device complexity and cost preclude application in brown field sites
Solution Approach 1:
The patent extracts the measurement of one phase (gas core static pressure) from the complex multiphase measurement problem. By measuring gas core pressure separately and correlating it with liquid layer pressure, the system determines both phase flow rates without requiring simultaneous multi-parameter measurements. This extraction approach reduces device complexity while maintaining reliability.
Solution Approach 2:
The patent changes the measurement parameter from direct phase flow measurement to pressure differential measurement. By measuring static pressure in the gas core and liquid layer rather than directly measuring phase velocities or densities, the system achieves reliable flow rate determination with simpler instrumentation suitable for brown field applications.
3Ease of manufacture
If simple pressure measurement methods are used, then cost is reduced, but the ability to determine both gas and liquid flow rates is insufficient
Solution Approach 1:
The patent measures pressure differentials that are sufficient (excessive) to determine both gas and liquid flow rates. By measuring differential gas core static pressure and differential liquid layer pressure, the system obtains more information than a single pressure measurement would provide, enabling simultaneous determination of both phase flow rates without requiring additional complex sensors.
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
Enables cost-effective determination of gas and liquid flow rates in multiphase flows by using a conduit with a constriction to measure differential pressures, providing a simple and unobtrusive method for flow rate calculation, suitable for low hydrocarbon producers.
Implementation Method 1
measuring the differential gas core static pressure between a position upstream of the constriction and a position at the constriction
Implementation Method 2
in a swirling flow of a multiphase mixture—where the swirling of the multiphase mixture separates the multiphase mixture, when the mixture comprises gas and liquid, into a gas core and a liquid outer layer
Data Source
AI summary
A method and system is provided for measuring a flow rate of a gas/liquid flow. The method and system for measuring the flow rate include flowing a swirling gas/liquid flow separated into a gas core and a liquid outer layer through a conduit containing a constriction having a reduced conduit cross-section, measuring the differential gas core static pressure between a position upstream of the constriction and a position at the constriction, measuring a further quantity which provides the flow rate of the gas, the flow rate of the liquid, or a correlation between the flow rate of the gas and the flow rate of the liquid, and determining the flow rates of the gas and the liquid from the differential gas core static pressure and said measured further quantity.