Distributed Acoustic Sensing Multiple Gauge Lengths
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Solution Overview
Problem
The increasing trend of using multiple Distributed Acoustic Sensing (DAS) systems simultaneously on a well for various applications is hindered by the limited availability of optical fiber downhole, making it expensive and sometimes prohibitive, as existing solutions either require re-processing of raw data to generate multiple gauge lengths or can only use one gauge length at a time.
Innovation Solution
A DAS system that incorporates multiple interferometers with different gauge lengths, allowing simultaneous use of multiple gauge lengths on a single optical fiber, enabling flexible sensitivity and spatial resolution for various applications without the need for re-processing raw data or switching between gauge lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple DAS systems are used simultaneously on a well to cover multiple applications, then the sensitivity and spatial resolution for different applications are improved, but the cost increases and the availability of optical fiber becomes a limiting factor
Solution Approach 1:
The patent implements a single DAS system that can operate with multiple different gauge lengths simultaneously, allowing one optical fiber to serve multiple monitoring applications (fracturing, production, integrity, microseismic) that previously required separate dedicated systems. The system uses a single optical fiber with multiple gauge lengths to provide universal monitoring capabilities across all applications.
Solution Approach 2:
The system dynamically changes the gauge length parameter of the DAS system without requiring physical reconfiguration or additional fibers. By adjusting the gauge length parameter electronically, the same optical fiber can be optimized for different applications in real-time, transforming a static single-purpose system into a dynamic multi-purpose system.
2Adaptability or versatility
If multiple DAS systems are deployed to meet different application requirements, then the monitoring capability for various applications is enhanced, but the device complexity and cost increase
Solution Approach 1:
The patent creates a universal DAS system that can adapt to multiple monitoring applications through electronic reconfiguration of gauge length. Instead of deploying multiple specialized DAS systems for different applications (fracturing monitoring, production monitoring, well integrity, microseismic detection), a single system provides all these functions by changing its operational parameters.
Solution Approach 2:
The patent merges multiple separate DAS systems into a single integrated system. By combining the functionality of multiple gauge-length-specific systems into one system that can operate with multiple gauge lengths simultaneously, the patent reduces system complexity while maintaining comprehensive monitoring capabilities across all applications.
3Quantity of substance
If existing solutions re-process raw data to generate multiple gauge lengths, then the need for multiple fibers is reduced, but the real-time simultaneous operation of multiple applications is not achieved
Solution Approach 1:
The patent performs preliminary action by capturing all gauge length information simultaneously during the initial measurement process. Instead of acquiring data at one gauge length and then re-processing it later to generate other gauge lengths, the system pre-captures all necessary information across multiple gauge lengths in real-time, eliminating subsequent processing delays.
Solution Approach 2:
The patent ensures continuous useful action by simultaneously acquiring data at multiple gauge lengths in real-time rather than sequentially processing a single gauge length. This continuous simultaneous measurement approach eliminates the time loss associated with re-processing raw data, as all gauge length information is captured continuously and concurrently.
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 simultaneous operation of multiple sensing applications with varying sensitivities and spatial resolutions, optimizing signal-to-noise ratios and reducing the need for multiple optical fibers, thereby enhancing the cost-effectiveness and efficiency of well monitoring.
Implementation Method 1
sending a first optical pulse down an optical fiber, wherein light from the first optical pulse is backscattered from positions along a length of the optical fiber according to coherent Rayleigh scattering
Implementation Method 2
Each application requires different gauge length for optimal sensitivity and spatial resolution
Data Source
AI summary
A method for distributed acoustic sensing includes sending a first optical pulse down an optical fiber, wherein light from the first optical pulse is backscattered from positions along a length of the optical fiber according to coherent Rayleigh scattering; splitting backscattered light from the first optical pulse into a first portion for a first interferometer and a second portion for a second interferometer, the first interferometer having a first gauge length and the second interferometer having a second gauge length, wherein the first gauge length is different from the second gauge length; detecting a first interferometric signal from the first interferometer responsive to the first portion of backscattered light; detecting a second interferometric signal from the first interferometer responsive to the second portion of backscattered light; and processing the first and second interferometric signals for two different sensing applications adapted for the first and second gauge lengths, respectively.