Critical Flow Nozzle Multiphase Flowmeter
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Solution Overview
Problem
Current oil nozzles in the oil and gas industry are unable to achieve precise and real-time measurement of the respective mass flowrates of the gas and liquid phases in multiphase fluids, especially at high-pressure wellheads, due to limitations in existing metering methods which result in significant errors and inaccuracies.
Innovation Solution
A critical flow nozzle flowmeter system that includes a throttling nozzle, a single-energy gamma ray detector, pressure sensors, and a temperature sensor, which measures the fluid's pressure and temperature ratios to determine the gas mass fraction and velocity slip ratio, allowing for the calculation of gas and liquid phase mass flowrates in a critical flow state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Venturi flowmeter is used to measure total volume flowrate and gamma ray technology is used to measure phase fractions, then the measurement system can provide phase separation data, but the method is not applicable for metering fluid flows in sonic speed at the throat of the oil nozzle
Solution Approach 1:
The invention transitions from using Venturi pressure difference method (inapplicable at sonic speed) to using critical flow parameters (pressure ratio, temperature) that are valid for sonic speed flow through nozzles. The measurement approach changes from volume flowrate-based to mass flowrate-based using critical flow equations that account for compressible fluid behavior at sonic conditions.
Solution Approach 2:
The invention introduces a nozzle as an intermediary device that transforms the flow conditions to enable measurement. The nozzle creates a critical flow state where the relationship between pressure, temperature, and mass flowrate becomes deterministic and measurable, serving as a mediator between the high-speed flow and the measurement system.
2Ease of operation
If empirical formulae based on pressure difference are used to estimate crude oil flowrate, then the method is simple to implement, but the metering involves significant errors
Solution Approach 1:
The invention replaces empirical mechanical pressure-difference-based estimation with a physics-based critical flow measurement system. Instead of relying on approximate empirical formulae, the system uses fundamental fluid dynamics equations for critical flow through nozzles, substituting mechanical estimation with theoretical calculation based on measured pressure and temperature.
Solution Approach 2:
The invention implements a feedback mechanism by continuously measuring pressure and temperature at the nozzle and using these measurements to calculate and update the mass flowrate in real-time. This closed-loop approach allows the system to adapt to changing flow conditions and maintain accuracy, unlike static empirical formulae.
3Stability of the object's composition
If a changeless metering equation is used for long-term applications, then the method is simple and consistent, but it results in significant errors because pressure and gas mass fraction dynamically vary in the oil well life cycle
Solution Approach 1:
The invention transitions from a static, changeless metering equation to a dynamic measurement system that continuously adapts to changing conditions. By measuring pressure and temperature in real-time and using critical flow equations that account for varying gas mass fraction and wellhead pressure, the system maintains accuracy throughout the oil well's life cycle despite dynamic changes in flow conditions.
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 real-time and precise measurement of the mass flowrates of the gas and liquid phases in multiphase fluids, improving the accuracy of throughput control and production management by utilizing the critical flow nozzle flowmeter and specific equations to calculate the respective flowrates.
Implementation Method 1
a single-energy gamma-ray detector is used to measure the respective phase fractions of the gas and liquid phases
Implementation Method 2
at the throat of the oil nozzle, the fluid flows in a sonic speed
Implementation Method 3
measuring pressure and temperature and after separating oil well products
Data Source
AI summary
A method for measuring respective flowrates of gas phase and liquid phase in a multiphase fluid using a critical flow nozzle flowmeter. The critical flow nozzle flowmeter includes a throttling nozzle having an inlet, an outlet and a throat, and the throat has a smallest flow area for flowing fluid; a gamma ray detector, including a gamma ray emitter and a gamma ray receiver, arranged in a way allowing the gamma ray emitted by the gamma ray emitter to pass through a cross-section at the inlet of the throttling nozzle in a diametrical direction to reach the gamma ray receiver; pressure sensors respectively configured for measuring the pressure P1 at the inlet of the throttling zone and the pressure P2 at the outlet of the throttling nozzle; and a temperature sensor configured for measuring the temperature T1 at the inlet of the throttling nozzle.