Downhole In-Situ Calibration of Angular Rate Sensors
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Solution Overview
Problem
Existing Rotary Steerable Systems (RSS) require periodic recalibration of angular rate sensors and magnetometers, which is typically done in a factory lab, leading to high costs and complex logistics, and is not accurate due to lack of downhole conditions consideration.
Innovation Solution
The method involves downhole in-situ calibration of angular rate sensors and magnetometers within the RSS, allowing for real-time adjustment based on actual downhole conditions such as temperature, eliminating the need for factory lab recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic recalibration is performed in a factory lab, then sensor measurement accuracy can be maintained, but cost and logistical complexity increase significantly
Solution Approach 1:
The system performs self-calibration by using the known Earth's gravitational field and magnetic field as reference standards. The BHA autonomously executes calibration sequences without requiring external factory lab resources, eliminating the need for periodic retrieval and external recalibration services.
Solution Approach 2:
The calibration system uses universally available natural references (Earth's gravity and magnetic fields) that are accessible anywhere in the downhole environment. This universal approach replaces the need for specialized factory lab equipment and procedures.
2Measurement precision
If sensors with tight specifications are used, then measurement precision is improved, but cost increases and logistics become more complex
Solution Approach 1:
The system changes the operational parameters by performing frequent in-situ recalibrations rather than relying on initial factory calibration. This dynamic approach compensates for using sensors with relaxed specifications, maintaining measurement precision through periodic parameter updates rather than requiring high-precision hardware.
3Measurement precision
If recalibration is performed in a factory lab, then calibration can be done with controlled conditions, but it does not account for actual downhole conditions
Solution Approach 1:
The system performs preliminary calibration actions at the start of each drilling operation or after specific events (tool face changes, temperature shifts). This preliminary calibration prepares the sensors for the specific downhole conditions they will encounter, accounting for temperature, pressure, and magnetic field variations unique to each well.
Solution Approach 2:
The system introduces natural downhole references (Earth's magnetic field and gravitational field) as intermediaries between the sensors and the calibration process. These intermediaries are always present in the downhole environment and provide stable reference signals that adapt to local conditions.
Data Source
AI summary
A method for calibrating the sensors present within a drilling tool, whereby the calibration occurs downhole and in-situ within the drilling tool. The calibration method may use the rotation of the drilling tool which typically occurs during drilling operations, whereby the drilling tool is rotating along the axis which follows the drilling trajectory. Direction and speed of rotation of the drilling tool may contribute to the in-situ calibration of the sensors, which may include angular rate sensors, magnetometers, and accelerometers.