Subsea Multiphase Flowmeter Hybrid Infrared Acoustic Measurement
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Solution Overview
Problem
Current subsea multiphase flowmeters face challenges such as high costs, sensitivity to salinity and gas, limited flexibility in measuring varying flow conditions, and the need for frequent calibrations, while traditional nuclear-based technologies are hindered by regulatory issues and short lifespans.
Innovation Solution
A hybrid system combining infrared water-cut measurement technology and in-well fiber-optic flow measurement, which measures subsea water-in-liquid ratios and speed of sound to calculate phase fractions and flow rates without nuclear components, offering robustness and flexibility in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional nuclear-based flowmeters are used, then measurement capability is provided, but device complexity and regulatory compliance difficulty increase
Solution Approach 1:
The patent removes nuclear components from the flowmeter system entirely, extracting only the necessary measurement functions (acoustic velocity, density, temperature, pressure) that can be achieved through non-nuclear means. This eliminates regulatory compliance requirements while maintaining measurement capability.
Solution Approach 2:
The patent replaces nuclear-based measurement mechanisms with acoustic and thermodynamic measurements. Specifically, it uses speed of sound measurements through the fluid combined with PVT data to determine phase fractions, substituting the nuclear interaction mechanism with acoustic wave propagation through different phases.
2Measurement precision
If conventional multiphase meters are deployed, then flow measurement is achieved, but cost increases significantly
Solution Approach 1:
The patent employs standard industrial sensors (acoustic transducers, temperature sensors, pressure sensors) that are commercially available and relatively inexpensive compared to specialized nuclear or complex capacitive multiphase meters. These standard components can be replaced more easily and at lower cost.
Solution Approach 2:
The patent replaces expensive specialized multiphase metering hardware with a combination of standard acoustic measurement equipment and computational analysis using PVT models, significantly reducing hardware costs while maintaining measurement accuracy.
3Measurement precision
If existing measurement techniques are used, then phase fraction data is obtained, but frequent calibrations are required
Solution Approach 1:
The system performs self-calibration by continuously measuring acoustic velocity, temperature, and pressure, then using these measurements with PVT models to determine phase fractions. The measurements themselves provide the calibration reference, eliminating the need for external calibration procedures.
Solution Approach 2:
The system uses real-time feedback from multiple sensors (acoustic velocity, temperature, pressure) to continuously update phase fraction calculations. This closed-loop approach maintains measurement accuracy without requiring periodic manual calibration interventions.
4Measurement precision
If traditional flowmeters are installed, then measurement capability is provided, but sensitivity to environmental factors increases
Solution Approach 1:
The patent introduces PVT (Pressure-Volume-Temperature) models as an intermediary layer between raw sensor measurements and phase fraction calculations. These models account for the effects of salinity, gas content, and emulsions by providing thermodynamic relationships that correct for these interfering factors.
Solution Approach 2:
The system measures multiple parameters (acoustic velocity, temperature, pressure) rather than relying on a single measurement mode. By combining these parameters with PVT models, the system can distinguish between effects caused by phase composition versus effects caused by environmental factors like salinity and gas content.
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 solution provides accurate, cost-effective, and flexible multiphase flow measurement capable of handling high gas volume fractions and varying flow conditions, with reduced maintenance needs and immunity to corrosion and erosion, enabling precise phase fraction and flow rate determination in subsea environments.
Implementation Method 1
measuring a subsea water-in-liquid ratio (WLRss) of the fluid mixture
Implementation Method 2
measuring a speed of sound (SoS) through the fluid mixture in a conduit disposed in the well
Implementation Method 3
determining a bulk flow velocity of the fluid mixture in the conduit
Data Source
AI summary
Multiphase flow measurement in extreme environments such as subsea or in-well is a difficult task for many reasons including reliability, survivability, and longevity issues; accessibility to the equipment; and complexity of the varying flow field as a function of position and time. Embodiments of the present invention provide techniques and apparatus for performing subsea multiphase flow measurement by combining two technologies. One is based on infrared water-cut measurement technology which is capable of measuring water and oil concentrations in multiphase flow with up to 99.5% gas volume fractions. The second technology is based on in-well fiber-optic flow measurement capable of resolving gas and total liquid flow through the measurements of flow velocity, fluid mixture speed of sound, and absolute pressure and temperature at meter location. This hybrid system represents an approach to subsea multiphase metering that may offer advantages compared to traditional systems for some applications.