Optical Fiber Wrapped Tool for Downhole Acoustic Sensing
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Solution Overview
Problem
Conventional acoustic exploration techniques face challenges in precisely controlling the azimuth direction of tools, leading to complex hardware designs and long operation times due to the need for numerous acoustic sensors, which limits real-time data preprocessing and logging intervals in geophysical exploration.
Innovation Solution
A system employing a tool wrapped with an optical fiber and an orientation sensor, combined with a processing system that includes an optical interrogation system, allows for the collection and combination of tool orientation and strain data to determine acoustic characteristics of a geologic formation, using techniques like Brillouin Optical Coherence Domain Reflectometry for precise strain measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acoustic sensors are used to control azimuth direction, then acoustic data can be obtained, but device complexity increases and operation time increases
Solution Approach 1:
The patent replaces conventional acoustic sensors with optical fiber sensing technology. The optical fiber wrapped around the tool body detects strain caused by acoustic waves, converting mechanical/acoustic measurements into optical measurements. This substitution eliminates the need for complex acoustic sensor arrays while maintaining measurement capability, directly resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent introduces optical fiber as an intermediary element between the acoustic field and the measurement system. The optical fiber acts as a mediator that translates acoustic strain into optical signal changes detectable by the interrogation system. This intermediary approach simplifies the overall system architecture while preserving the ability to obtain precise acoustic data
2Measurement precision
If conventional acoustic sensors are used, then acoustic data can be obtained, but operation time increases
Solution Approach 1:
The optical fiber sensing system enables faster data acquisition compared to conventional acoustic sensors. The optical interrogation system can process strain measurements from the optical fiber more rapidly than acoustic sensor arrays, reducing the overall operation time while maintaining acoustic data acquisition capability
Solution Approach 2:
The optical fiber is pre-wrapped around the tool body before deployment, establishing the sensing configuration in advance. This preliminary setup eliminates the need for complex real-time sensor positioning and calibration during operation, thereby reducing operation time while ensuring measurement precision
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 enables efficient measurement of elastic properties and acoustic data with high resolution, reducing complexity and operation time, allowing for real-time data processing and improved geophysical exploration capabilities.
Implementation Method 1
A technique employs a tool wrapped with an optical fiber... strain data obtained from a location along the wrapped optical fiber... using techniques like Brillouin Optical Coherence Domain Reflectometry for precise strain measurements
Data Source
AI summary
A technique facilitates geophysical exploration by employing a tool wrapped with an optical fiber. Additionally, an orientation sensor is coupled to the tool and is operable to provide data regarding orientation of the tool. A processing system, which may include an optical interrogation system, cooperates with the optical fiber and with the orientation sensor to obtain acoustic data. For example, the processing system collects tool orientation data and also strain data obtained from a location along the wrapped optical fiber. The strain data results from excitation of an acoustic signal from a suitable acoustic source.