Axial Survey Sensor Dynamic Calibration via Azimuthal Fitted Curves
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Solution Overview
Problem
Tri-axial accelerometers and magnetometers used in oil and gas well characterization suffer from systematic errors due to aging and physical changes caused by high-temperature and high-shock exposures, leading to calibration errors that affect measurement precision and consistency, especially at near-vertical or near-horizontal inclinations.
Innovation Solution
A method for dynamic calibration of axial survey sensors, which involves obtaining a data log as a function of azimuthal angle, generating a fitted curve to represent calibration errors, and extracting calibration parameters to correct for misalignment errors, allowing for real-time calibration during drilling operations using a computer processor in a bottom-hole assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laboratory calibration is performed for scale factor, bias, and misalignment, then initial measurement accuracy is improved, but systematic errors accumulate over time due to sensor aging and environmental exposure
Solution Approach 1:
The system performs preliminary calibration actions by establishing reference measurements at multiple azimuthal angles before actual drilling operations. These preliminary data logs are used to generate fitted curves that represent calibration errors, which are then applied as correction factors during subsequent drilling operations, preventing error accumulation rather than addressing it after the fact.
Solution Approach 2:
The system continuously monitors axial survey sensor measurements at multiple azimuthal angles during drilling operations and uses this feedback to dynamically update calibration parameters. The computer processor compares actual measurements against expected values and adjusts calibration parameters in real-time, creating a closed-loop system that maintains measurement accuracy despite sensor aging and environmental changes.
2Loss of time
If calibration is performed periodically every 2-3 months to 6 months, then labor and equipment costs are reduced, but bias errors and misalignment errors affect measurements between calibration periods
Solution Approach 1:
The system performs calibration actions continuously during normal drilling operations rather than requiring separate calibration periods. By measuring axial survey sensor data at multiple azimuthal angles throughout the drilling process, the system continuously updates calibration parameters, ensuring measurement accuracy is maintained without interrupting drilling operations for periodic recalibration.
Solution Approach 2:
The system performs self-calibration by using its own operational data to update its calibration parameters. The computer processor analyzes measurements taken during normal drilling operations and automatically adjusts calibration parameters without requiring external calibration equipment or personnel, enabling the system to maintain its own measurement accuracy independently between traditional calibration periods.
3Measurement precision
If axial survey sensor measurements are taken at multiple azimuthal angles during drilling operations, then calibration error detection is improved, but data processing complexity increases
Solution Approach 1:
The system uses fitted curves, specifically sinusoidal functions, to represent calibration errors as a function of azimuthal angle. This curved mathematical model naturally captures the periodic nature of calibration errors that occur at different orientations, providing an elegant and computationally efficient way to characterize and correct errors without requiring complex multi-dimensional analysis of the raw measurement data.
Solution Approach 2:
The system transforms the complex multi-angle measurement data into a simplified set of calibration parameters that define the fitted curve. By converting numerous azimuthal angle measurements into a few key parameters (amplitude, phase, offset) that characterize the calibration error, the system reduces data processing complexity while maintaining the ability to detect and correct calibration errors accurately.
Data Source
AI summary
A method to perform a drilling operation. The method includes calibrating an axial survey sensor of a bottom hole assembly (BHA) by obtaining, from the axial survey sensor, a data log as a first function of azimuthal angle within a borehole, generating, by a computer processor of the BHA and using a pre-determined algorithm, a fitted curve as a second function of the azimuthal angle, wherein the fitted curve is generated based on the data log to represent a calibration error of the axial survey sensor, and extracting, by the computer processor of the BHA, a calibration parameter from the fitted curve. Accordingly, the drilling operation is performed using at least the axial survey sensor based on the calibration parameter.