Distributed Acoustic Sensing Noise Attenuation Using CNN

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Solution Overview

Problem

Distributed Acoustic Sensing (DAS) systems face challenges in attenuating random noise from fiber-optic cables, which obscures seismic events and can incorrectly identify seismic signals as noise, leading to incomplete noise removal and signal distortion.

Innovation Solution

A method using a structured Convolutional Neural Network (CNN) to separate seismic signals from random noise by estimating power spectra, employing a Wiener filter to minimize mean square error, and training on noise windows to distinguish between seismic and noise signals, thereby improving noise attenuation without damaging the signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional noise attenuation methods are used, then some noise is reduced, but seismic signals are incorrectly identified as noise and signal distortion occurs

Engineering Contradiction:
Improverandom noise attenuationVSAvoidsignal integrity
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces conventional mechanical signal processing methods with machine learning-based noise attenuation. A neural network model is trained to distinguish between seismic signals and noise, using deep learning to achieve more accurate noise removal without distorting seismic events. This substitution of processing methodology enables effective noise attenuation while preserving signal integrity.

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

Solution Approach 2:

The patent changes the approach from fixed conventional filtering parameters to adaptive machine learning models. The neural network dynamically adjusts its noise attenuation characteristics based on training data, allowing it to adapt to different seismic conditions and avoid misidentifying signals as noise, thereby maintaining signal integrity during attenuation.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If aggressive noise removal is applied, then noise is reduced, but seismic events are distorted or lost

Engineering Contradiction:
Improvenoise levelVSAvoidseismic event detection accuracy
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent substitutes traditional mechanical filtering with neural network-based processing that learns to distinguish between noise and seismic events. This allows aggressive noise removal while maintaining detection accuracy, as the neural network understands the temporal and spectral characteristics of both noise and signals, preventing distortion of seismic events during attenuation.

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

Solution Approach 2:

The patent employs feedback mechanisms where the neural network continuously refines its noise attenuation based on training data and performance evaluation. This feedback loop ensures that noise is effectively removed while preserving seismic event characteristics, as the model adjusts its attenuation strength based on the presence and quality of detected seismic signals.

Inventive Principle:
Principle #23Feedback

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

The method effectively attenuates random noise by 26 dB compared to conventional methods, providing a cleaner seismic signal with no residual noise energy, while maintaining signal integrity.

Implementation Method 1

separate seismic signals from random noise by estimating power spectra

Methodology Applied
Scientific EffectPower spectrum estimation:

Implementation Method 2

employing a Wiener filter to minimize mean square error

Methodology Applied
Scientific EffectWiener filtering: Filter (electronic)

Implementation Method 3

the fiber-optic cable 12 contains many impurities 13 which cause back-scattering 15

Methodology Applied
Scientific EffectBack-scattering: Scattering

Data Source

PatentEP3935419B1System and method for reducing noise in distributed acoustic sensing data
Publication Date: 2023.11.01 CHEVRON USA INC
  • EP3935419B1 patent drawingFigure 1
  • EP3935419B1 patent drawingFigure 2
  • EP3935419B1 patent drawingFigure 3

AI summary

A method is described for improving distributed acoustic sensing (DAS) seismic data in order to identify seismic events which includes receiving a DAS seismic dataset recorded by a fiber-optic cable in a borehole drilled through a subsurface volume of interest; identifying a portion of the seismic dataset including random noise with no signal to generate a windowed noise dataset; transforming the windowed noise dataset into a noise power spectrum; training a machine-learning algorithm using the noise power spectrum; using the machine-learning algorithm to remove random noise from the DAS seismic dataset to generate a noise-attenuated seismic dataset; and identifying the seismic events in the noise-attenuated seismic dataset. The method is executed by a computer system.