Downhole Sonic Tool Noise Attenuation via Motion Sensor Decoupling
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Solution Overview
Problem
Downhole sonic measurement tools face challenges in acquiring noise-free pressure amplitude measurements due to tool-borne noise, which is similar in timing to energy propagating through the casing, complicating the evaluation of cement bond quality between the casing and the borehole.
Innovation Solution
The implementation uses a combination of tool motion sensors, such as accelerometers, to estimate and remove tool-borne noise from pressure measurements by decoupling the motion sensor data from well fluid and formation measurements, allowing for passive attenuation of noise through signal processing without the need for active noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tool motion sensors are used to measure tool-borne noise, then noise attenuation is improved, but device complexity increases
Solution Approach 1:
The patent uses tool motion sensors (accelerometers or velocity sensors) as intermediary devices to indirectly measure tool-borne noise. Instead of directly measuring noise in the pressure signal, the system measures tool motion and uses this information to estimate and remove the noise component from pressure amplitude measurements, thereby improving measurement precision without directly complicating the pressure sensing system
Solution Approach 2:
The patent replaces direct mechanical/acoustic noise measurement with a substituted approach using motion sensors. By measuring tool motion (acceleration or velocity) and converting it to an estimate of tool-borne noise through signal processing, the system substitutes a potentially simpler motion sensing mechanism for complex direct noise measurement, achieving noise attenuation while managing device complexity
2Measurement precision
If active noise cancellation is used, then noise attenuation is improved, but use of energy increases
Solution Approach 1:
The patent extracts the tool-borne noise component from the pressure signal by using tool motion sensor data to identify and remove the noise portion. This passive extraction approach eliminates noise through signal processing rather than active cancellation, reducing energy consumption while maintaining measurement precision
Solution Approach 2:
The patent converts the harmful effect of tool-borne noise into a beneficial measurement opportunity. By using the same tool motion that generates noise also serves as a reference to characterize and remove the noise from pressure measurements, the system transforms the noise source into a useful reference signal for attenuation, avoiding additional energy-intensive active cancellation systems
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 effectively attenuates tool-borne noise, improving the accuracy of cement bond evaluation by isolating and subtracting noise from pressure signals, thereby enhancing the reliability of acoustic logging data in downhole environments.
Implementation Method 1
an accelerometer attached to the tool body to sense a component related to the pressure sensed by the pressure sensor attributable to tool-borne noise
Data Source
AI summary
A technique includes receiving data representing a measurement acquired by a tool motion sensor of a downhole sonic measurement tool; and receiving data representing a measurement acquired by a pressure sensor of the sonic measurement tool. The technique includes modifying the measurement acquired by the pressure sensor based at least in part on the measurement acquired by the tool motion sensor to attenuate tool borne noise.