Switchable Distributed Acoustic Sensing for Wellbores

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Solution Overview

Problem

Distributed acoustic sensing systems face challenges in efficiently switching between single-mode and multi-mode optical fiber operations in wellbore environments due to issues like modal dispersion in multi-mode fibers over longer lengths, requiring hardware changes for optimal sensing operations.

Innovation Solution

A distributed acoustic sensing system architecture that includes switches to selectively route light signals between single-mode and multi-mode optical fibers, allowing operators to switch between modes without hardware changes, using a common light source and circulators to manage signal transmission and reflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If multi-mode optical fiber is used for sensing operations, then shorter fiber lengths can be used, but modal dispersion occurs over longer lengths reducing measurement accuracy

Engineering Contradiction:

Improveoptical fiber lengthVSAvoidsensing accuracy

Core Design Contradiction:

Length of stationary objectVSMeasurement precision

Solution Approach 1:

The system dynamically switches between single-mode and multi-mode optical fibers based on the required sensing distance and accuracy. For shorter distances where multi-mode fiber is sufficient, the system provides faster measurement speeds. For longer distances where single-mode fiber is needed to avoid modal dispersion, the system automatically selects the appropriate fiber type, making the optical fiber configuration adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameter of the optical fiber system by switching between different fiber modes (single-mode and multi-mode) and corresponding Raman laser wavelengths. This allows optimization of the fiber characteristics for different measurement scenarios, changing the effective parameters of the sensing system to match the specific application requirements.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If hardware changes are made to switch between single-mode and multi-mode operations, then optimal sensing performance can be achieved, but system complexity and installation time increase

Engineering Contradiction:

Improvesensing performanceVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system achieves multi-functionality by integrating both single-mode and multi-mode optical fiber capabilities into a single sensing system. The Raman laser can operate at different wavelengths and the system can switch between fiber types, allowing one system to perform both single-mode and multi-mode sensing operations without requiring separate hardware installations for each mode.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses an intermediary switching mechanism that allows seamless transition between single-mode and multi-mode operations. The switch and wavelength selection mechanism act as intermediaries that manage the transition between different fiber types and operating modes, abstracting the complexity from the user while maintaining optimal sensing performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If single-mode optical fiber is used for longer transmission distances, then measurement accuracy is maintained, but measurement speed decreases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidmeasurement speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The system dynamically adapts its measurement approach by selecting between single-mode and multi-mode fiber operations based on the specific measurement requirements. When high speed is needed and distance permits, the system uses multi-mode fiber for faster measurements. When accuracy is paramount and distance is long, it switches to single-mode fiber, making the speed-accuracy tradeoff dynamic rather than fixed.

Inventive Principle:

Principle #15Dynamics

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 tailored sensing operations in wellbores by selecting the optimal mode for signal transmission, improving measurement speed and accuracy without requiring hardware installation or removal, thus enhancing operational flexibility and efficiency.

Implementation Method 1

a light source of the interrogation device may transmit a light signal downhole in the wellbore through the optical fiber to sensors positioned on the optical fiber

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The sensors may transmit a reflection of the light signal back toward an optical detector

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11340365B2Switchable distributed acoustic sensing system for wellbore environment

Publication Date: 2022.05.24 HALLIBURTON ENERGY SERVICES INC

AI summary

An interrogation system includes a light signal switch and a reflection signal switch. The light signal switch may be communicatively coupled to an optical light source. The light signal switch may route a light signal generated by the light source downhole in a wellbore through a single-mode optical fiber cable or a multi-mode optical fiber cable. The reflection signal switch may be communicatively coupled to the single-mode optical fiber cable and the multi-mode optical fiber cable. The reflection signal switch may route a reflection of the light signal from the signal-mode optical fiber cable or the multi-mode optical fiber cable to an optical detector.