Non-Invasive Fluid Flow Assessment Using Laser Doppler Vibrometry
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Solution Overview
Problem
Subsea oil and gas wells experience inefficient production due to noisy and volatile fluid flow, making it difficult to determine the contribution of each well, as existing methods are invasive, inaccurate, or require significant lag-time for feedback, resulting in subsea wells producing only 75% as much oil as surface wells.
Innovation Solution
A method and apparatus using high-frequency vibration measurement, specifically circumferential modes, to assess fluid flow in conduits, allowing real-time monitoring of individual well production without disrupting the flow, using a device like a Laser Doppler vibrometer to detect turbulent fluid flow-induced vibrations and process signals with high sampling rates connected to the speed of sound and pipe diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional flow monitoring methods are used, then measurement can be performed, but the methods are invasive, inaccurate, or require significant lag-time
Solution Approach 1:
The patent replaces traditional mechanical flow meters with acoustic wave-based measurement. Acoustic waves are transmitted through the fluid and the velocity of these waves is measured to determine flow rate. This non-invasive acoustic method eliminates the need for mechanical components that cause pressure drops and provide lagged feedback, achieving real-time measurement without sacrificing accuracy.
2Productivity
If subsea wells are operated with traditional monitoring, then infrastructure can be shared, but production efficiency is reduced to 75% of surface wells
Solution Approach 1:
The patent implements individual flow measurement for each wellstream before they are combined in the manifold. By measuring the acoustic wave velocity in each separate conduit leading to the manifold, the system segments the monitoring function, allowing individual well performance to be tracked independently. This enables operators to optimize each well's contribution to total production while maintaining the infrastructure efficiency of shared subsea facilities.
3Measurement precision
If invasive measurement devices are introduced into the conduit, then flow can be measured, but the veracity of recovered data is compromised and fluid flow may be disrupted
Solution Approach 1:
The patent uses acoustic waves as an intermediary to measure flow without direct contact with the fluid. The acoustic waves pass through the fluid and interact with it minimally, allowing measurement of flow velocity and rate without introducing foreign objects that could contaminate the fluid or alter its flow characteristics. This maintains data veracity while enabling measurement.
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 accurate, real-time monitoring of fluid flow and composition in conduits, allowing for immediate adjustments to choke settings, thereby improving oil production efficiency and reducing the lag-time issue, potentially increasing subsea well production to match surface well production levels.
Implementation Method 1
measuring vibration of the conduit using a device for measuring vibration... using a device like a Laser Doppler vibrometer to detect turbulent fluid flow-induced vibrations
Implementation Method 2
the measured vibration of the conduit is a result of the fluid flow in the conduit and normally based on at least one circumferential mode of vibration
Data Source
AI summary
A method of assessing fluid flow in a conduit, the fluid comprising hydrocarbons, the method comprising the steps of: (a) measuring optical variances resulting from at least one circumferential mode of vibration of the conduit by directing a monochromatic light source, such as from a vibrometer, onto an external surface of the conduit thereby providing a measured vibration of the conduit as a result of fluid flow in the conduit. The data normally accurately measures velocity of the conduit usually considered to be wideband noise. Accordingly, sample rates are high, such as at least 5,000 times per second. The data is then assessed, for example by using a Fourier Transform, and a pre-trained algorithm to predict fluid flow at that point in the conduit, or upstream or downstream thereof. An associated apparatus is also disclosed. Embodiments of the invention can thus provide a non-invasive method and apparatus for providing information on the nature of flow regimes in pipelines, such as subsea pipelines which can be useful to optimise production and reduce well testing and/or downtime.