Downhole Optical Interferometry for Real-Time Wellbore Displacement
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Solution Overview
Problem
Conventional LiDAR and caliper techniques for wellbore displacement measurement are limited by operational range and require high reflectance, making them inadequate for precise wellbore characterization during high-power laser operations.
Innovation Solution
A downhole tool system with a laser head and sensing assembly that emits and receives laser and light beams to generate interferograms, allowing for real-time determination of wellbore characteristics and rock properties using wideband light sources and optical receivers, including photodetectors and spectrometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LiDAR is used for wellbore displacement measurement, then measurement capability is provided, but operational range is limited to above ten centimeters and high reflectance is required
Solution Approach 1:
The patent introduces an intermediary light source that emits light at wavelengths tuned to transmit through wellbore fluid, serving as a mediator between the laser beam and the rock formation. This intermediary light enables the sensing assembly to detect displacement effects caused by high-power laser operations even when direct LiDAR measurement is compromised by fluid interference or lack of reflectance
Solution Approach 2:
The patent replaces conventional mechanical LiDAR measurement systems with an optical interference-based detection system. By using optical receivers to detect interference patterns between reference light and light reflected from the rock formation, the system substitutes mechanical displacement measurement with optical field interference measurement, enabling detection in environments where conventional LiDAR fails
2Productivity
If high-power laser operations are performed on rock formations, then geo-steering and sweet spot classification are improved, but real-time detection of wellbore displacement and rock properties becomes more difficult
Solution Approach 1:
The patent implements continuous optical measurement during laser operations by maintaining simultaneous emission of the reference light beam and detection of interference patterns. The sensing assembly continuously monitors optical interference signals throughout the laser operation, enabling real-time detection of wellbore displacement and rock property changes without interrupting the high-power laser drilling or perforating process
Solution Approach 2:
The patent establishes a feedback mechanism where the sensing assembly continuously monitors optical interference patterns caused by laser-induced displacement, and this information is fed back to control the laser operations. The optical receivers detect interference between reference light and reflected light, providing real-time feedback on wellbore displacement and rock properties that can be used to adjust laser parameters for improved geo-steering
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 precise, real-time characterization of wellbore displacement and rock properties, providing a three-dimensional map of the wellbore environment, enhancing geo-steering and sweet spot classification.
Implementation Method 1
receive a reflected laser beam from the reservoir rock formation and a reflected light beam from the reservoir rock formation
Implementation Method 2
interfere the reflected laser beam with the reflected light beam to generate an interferogram
Data Source
AI summary
A downhole tool system includes a bottom hole assembly that includes a connector, a laser head, a light source emitter, and a sensing assembly. The connector is configured to couple to a downhole conveyance run into a wellbore to a reservoir rock formation. The laser head is configured to emit a laser beam toward the reservoir rock formation at a fixed frequency. The light source emitter is configured to emit a light beam toward the reservoir rock formation. The sensing assembly includes at least one optical receiver configured to (1) receive a reflected laser beam and a reflected light beam, and (2) interfere the reflected laser beam with the reflected light beam to generate an interferogram. The system includes a controller configured to perform operations including determining one or more wellbore characteristics based on the interferogram.