Variable Calibration Function for Downhole Logging Tools
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Solution Overview
Problem
Downhole logging tools face calibration challenges due to physical changes during drilling, rendering pre-calibration values obsolete as components like metal collars abrade, leading to inaccurate measurements.
Innovation Solution
A method for determining a variable calibration function using both pre- and post-logging calibration values, allowing for continuous or discrete, linear or non-linear adjustments based on changing tool attributes, which can be applied throughout the logging process to maintain measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-logging calibration is used for the entire logging interval, then the calibration process is simple and quick, but measurement accuracy deteriorates as tool attributes change during drilling
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static pre-logging calibration approach to a dynamic variable calibration function that adapts during the logging process. The calibration function continuously adjusts based on measured tool attributes (such as collar diameter) to maintain accuracy as the tool undergoes physical changes during drilling operations.
Solution Approach 2:
The patent implements parameter changes by using measured tool attributes (physical parameters) as inputs to adjust the calibration function. As tool attributes change during logging (e.g., collar abrasion), the calibration parameters are dynamically modified to reflect these changes, ensuring continuous measurement accuracy without requiring complete recalibration.
2Measurement precision
If tool attributes are monitored continuously to adjust calibration, then measurement accuracy is maintained, but the complexity of the logging system increases
Solution Approach 1:
The patent applies the self-service principle by enabling the logging system to automatically monitor its own tool attributes and self-adjust the calibration function without external intervention. The system measures its own physical changes (such as collar diameter variations) and autonomously updates the calibration parameters, eliminating the need for manual recalibration operations.
Solution Approach 2:
The patent implements feedback by creating a closed-loop system where tool attribute measurements are continuously fed back to the calibration function. This feedback mechanism allows the system to detect changes in tool conditions and automatically adjust calibration parameters in real-time, maintaining accuracy while simplifying the overall operational process.
Data Source
AI summary
The present disclosure relates to a method to calibrate logging measurements from a logging tool for which one or more attributes vary over the course of logging. A logging tool is provided and a pre-logging calibration function for the logging tool is obtained. Logging measurements are made using the logging tool, and a post-logging calibration function for the logging tool is obtained. A variable calibration function using the pre-logging calibration function and the post-logging calibration function is determined, and the logging measurements are calibrated using the variable calibration function. The variable calibration function may be discrete or continuous and linear or non-linear. A non-linear calibration function may be based on measurements of one or more of the varying attributes of the logging tool. A discrete calibration function may have three or more calibration factors.