Spiral Fiber DAS Sensing for Multiphase Interface Level Detection
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Solution Overview
Problem
Existing methods for measuring phase interface levels in multiphase fluids in vertical pipes, such as those used in hydrocarbon production, rely on radioactive or complex sensors that are costly, unreliable, and inaccurate, posing environmental and safety risks.
Innovation Solution
A method using a distributed optical fiber sensor spirally wound around the pipe, coupled with a DAS interrogator, to determine phase interface levels by analyzing power spectral density and integrating it over a predefined frequency band to create a matrix representation for accurate interface detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gamma-ray level sensors are used to measure phase interface level, then measurement capability is provided, but radioactive radiation sources cause environmental harm and safety risks
Solution Approach 1:
The patent replaces gamma-ray level sensors (radioactive measurement system) with ultrasonic sensors (acoustic measurement system). The ultrasonic sensor emits acoustic waves that reflect off the phase interface, and the travel time of the reflected signal is directly proportional to the traveled distance, enabling non-radioactive measurement of phase interface levels.
Solution Approach 2:
The patent introduces an intermediary substance (acoustic waves) to transfer measurement information. Instead of using radioactive gamma rays that directly interact with the fluid, ultrasonic waves serve as an intermediary carrier that reflects off the phase interface, allowing indirect measurement without harmful radiation exposure.
2Measurement precision
If gamma-ray level sensors are used, then phase interface level can be measured, but the detectors are complex components with high cost and low reliability
Solution Approach 1:
The patent replaces complex gamma-ray detectors with simpler ultrasonic sensors. The ultrasonic sensor system consists of a transmitter that emits acoustic waves and a receiver that detects reflected waves, eliminating the need for complex radioactive detection equipment while achieving reliable phase interface level measurement.
Solution Approach 2:
The patent employs ultrasonic sensors that are less expensive and more reliable than gamma-ray detectors. These sensors can be easily replaced if needed and do not require the complex shielding and safety infrastructure required for radioactive sources, reducing both initial cost and operational complexity.
3Object-affected harmful factors
If ultrasonic sensors are used to measure phase interface level, then non-radioactive measurement is achieved, but the sensor emits ultrasonic pulses that require travel time measurement
Solution Approach 1:
The patent uses periodic ultrasonic pulse emission where the sensor emits a series of timed acoustic pulses. By measuring the travel time of reflected pulses at regular intervals, the system continuously monitors phase interface levels with high temporal resolution, transforming a potentially difficult single measurement into a series of manageable periodic measurements.
Solution Approach 2:
The patent implements a feedback mechanism where the ultrasonic sensor measures the travel time of reflected acoustic waves and uses this information to continuously update the phase interface level measurement. This feedback loop allows the system to compensate for variations in acoustic wave propagation and maintain accurate measurements despite environmental changes.
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, non-invasive, and accurate monitoring of phase interface levels with multi-parameter capabilities, including fluid distribution and pressure monitoring, without the need for maintenance, using a cost-effective and environmentally friendly solution.
Implementation Method 1
a sensor emits ultrasonic pulses which are reflected by the outer surface of the reservoir. The travel time of the reflected ultrasonic signal is directly proportional to the traveled distance.
Implementation Method 2
a sensor emits ultrasonic pulses which are reflected by the outer surface of the reservoir. The travel time of the reflected ultrasonic signal is directly proportional to the traveled distance.
Implementation Method 3
the different phases of the mixture separate naturally by gravity: the water rests at the bottom of the reservoir, the oil is above the water and the gas is above the oil.
Data Source
AI summary
A method and a system for the time determination of a phase interface level of a multiphase fluid present in a vertical pipe, include placing a distributed optical fiber sensor comprising an optical fiber cable wound in spiral around the pipe and optically coupled to a DAS interrogator, determining, from the data acquired by the DAS interrogator, the power spectral density over a predetermined duration and for each point of a discretized length of the optical fiber cable, integrating the power spectral density over a predefined frequency band for each point of the discretized length of the optical fiber cable, and setting in matrix form the results of the integration of the power spectral density in order to determine at least one interface level of the multiphase fluid.