DAS Temperature Sensing via Acoustic Signal Separation

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Solution Overview

Problem

Conventional Distributed Temperature Sensing (DTS) systems require long integration times to measure temperature profiles, limiting their ability to detect rapid temperature changes and providing low temporal resolution in harsh environments such as downhole applications.

Innovation Solution

The implementation of Distributed Acoustic Sensing (DAS) using optical fibers, which transmit and receive interrogation signals to process data and separate temperature change components, enabling real-time measurement of temperature changes with high precision by analyzing low-frequency oscillations in DAS signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional DTS systems are used to measure temperature profiles, then temperature measurement capability is provided, but integration time is long which limits temporal resolution

Engineering Contradiction:
Improvetemperature measurement capabilityVSAvoidintegration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces conventional DTS measurement methodology with DAS technology, substituting the mechanical/optical measurement approach. DAS uses acoustic wave propagation and backscatter analysis to infer temperature changes, enabling much faster measurement响应 times while maintaining temperature measurement capability through a different physical mechanism

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from direct temperature measurement in conventional DTS to acoustic signal analysis in DAS. By measuring acoustic backscatter signals and analyzing their characteristics (amplitude, frequency, timing), the system derives temperature information with much faster response, transforming the measurement approach from thermal field direct sensing to acoustic field indirect sensing

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If DAS measurement data is processed to separate temperature components, then temporal resolution is improved, but data processing complexity increases

Engineering Contradiction:
Improvetemporal resolutionVSAvoiddata processing complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent extracts and separates the temperature-related acoustic signal components from the total DAS measurement data. By isolating the specific frequency bands and signal characteristics associated with thermal expansion and contraction, the system extracts temperature information while filtering out other environmental noise, achieving high temporal resolution through selective signal extraction

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces intermediate processing steps including signal filtering, frequency analysis, and component separation algorithms. These intermediary processes act as mediators between the raw DAS data and the final temperature profile, breaking down the complex processing task into manageable stages that improve temporal resolution while organizing the computational complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach allows for real-time monitoring and high-resolution temperature change detection, combining with absolute temperature measurements to generate detailed temperature profiles at a higher temporal resolution than traditional DTS systems, effectively addressing the limitations of existing technologies.

Implementation Method 1

taking distributed acoustic sensing (DAS) measurement data by transmitting interrogation signals into an optical fiber disposed in an environment of interest, and receiving reflected signals over a selected time period from the optical fiber

Methodology Applied
Scientific EffectDistributed Acoustic Sensing (DAS):

Implementation Method 2

enabling real-time measurement of temperature changes with high precision by analyzing low-frequency oscillations in DAS signals

Methodology Applied
Scientific EffectLow-frequency oscillations in DAS signals:

Data Source

PatentUS10208586B2Temperature sensing using distributed acoustic sensing
Publication Date: 2019.02.19 BAKER HUGHES CO
  • US10208586B2 patent drawing
  • US10208586B2 patent drawing

AI summary

An embodiment of a method of measuring temperatures includes: taking distributed acoustic sensing (DAS) measurement data by transmitting interrogation signals into an optical fiber disposed in an environment of interest, and receiving reflected signals over a selected time period from the optical fiber; processing the DAS measurement data to separate components of the DAS data associated with changes in temperature; and generating a temperature change profile for the selected time period based on the separated components of the DAS data.