Interferometer-Based Downhole Optical Analysis Tool
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Solution Overview
Problem
Current logging technologies face challenges in obtaining accurate and reliable downhole data due to hostile drilling environments and limited communication bandwidths, particularly in logging while drilling (LWD) and tubing-conveyed logging, which affect the quality and completeness of formation measurements.
Innovation Solution
The implementation of an interferometer-based system for optical analysis downhole, which introduces an interferogram by varying the propagation time of light waves, allowing for spectral analysis of formation fluids and materials through transmission, reflection, or fluorescence, enabling laboratory-quality measurements even in harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LWD or tubing-conveyed logging is used to enable measurements in hostile environments or difficult-to-reach locations, then adaptability and productivity are improved, but measurement precision and reliability deteriorate due to hostile drilling environments and limited communication bandwidths
Solution Approach 1:
The patent replaces traditional electrical sensing and telemetry systems with an optical-based interferometry system. Light waves are used to carry measurement information through optical fibers, substituting electrical signals that are vulnerable to electromagnetic interference in hostile drilling environments. This enables laboratory-quality measurements while maintaining adaptability to difficult operating conditions.
Solution Approach 2:
The patent introduces optical fibers as an intermediary medium to transmit measurement data from the downhole environment to the surface. The optical fiber acts as a protected channel that isolates sensitive measurements from the hostile electromagnetic environment while enabling high-bandwidth data transmission, thus preserving measurement precision in adaptable logging configurations.
2Measurement precision
If traditional electrical sensing systems are used in wireline logging to ensure measurement precision, then measurement precision is improved, but adaptability to horizontal or ascending boreholes deteriorates due to mechanical support limitations
Solution Approach 1:
The patent replaces the mechanical wireline support system with a tubing-conveyed deployment method combined with optical sensing. The logging tool is pushed or conveyed through tubing rather than suspended by wireline, enabling access to horizontal and ascending boreholes. Optical sensors maintain measurement precision while the mechanical constraints are removed.
Solution Approach 2:
The patent uses optical fibers as an intermediary to transmit data from tools deployed in difficult-to-reach locations. The optical fiber connection allows the tool to be mechanically supported by tubing while maintaining electrical isolation and high-quality data transmission, enabling versatility in borehole geometry without sacrificing measurement precision.
3Adaptability or versatility
If tubing-conveyed logging is used to enable access to difficult locations, then adaptability is improved, but communication bandwidth is limited requiring data storage and download, which increases loss of time
Solution Approach 1:
The patent replaces limited electrical communication channels with high-bandwidth optical fiber communication. Optical fibers can transmit large volumes of data at high speeds, eliminating the bottleneck that requires data to be stored in memory and downloaded later. This enables real-time or near-real-time data transmission while maintaining the ability to access difficult locations.
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 precise and reliable downhole fluid analysis, providing accurate spectral data that can be processed to determine contamination levels, fluid composition, and PVT properties, improving the accuracy of formation evaluation and completion strategies.
Implementation Method 1
introduces an interferogram by varying the propagation time of light waves
Implementation Method 2
The encounter can take various forms, including transmission/attenuation through the sample
Implementation Method 3
reflection off the sample
Implementation Method 4
fluorescence excitation
Implementation Method 5
processing electronics that perform a Fourier Transform to obtain the spectrum
Data Source
AI summary
Various systems and methods for performing optical analysis downhole with an interferogram (a light beam having frequency components with a time variation that identifies those frequency components. The interferogram is produced by introducing an interferometer into the light path, with the two arms of the interferometer having a propagation time difference that varies as a function of time. Before or after the interferometer, the light encounters a material to be analyzed, such as a fluid sample from the formation, a borehole fluid sample, a core sample, or a portion of the borehole wall. The spectral characteristics of the material are imprinted on the light beam and can be readily analyzed by processing electronics that perform a Fourier Transform to obtain the spectrum or that enable a comparison with one or more templates. An interferometer designed to perform well in the hostile environments downhole is expected to enable laboratory-quality measurements.