Gravity Acceleration Measurement in Rotating Drilling Tools
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Solution Overview
Problem
Existing Measurement While Drilling (MWD) systems face challenges in accurately measuring well trajectory in real-time due to interference from centrifugal, vibration, and shock accelerations during the rotating drilling process, leading to inefficient drilling and reduced accuracy in inclination and toolface angle measurements.
Innovation Solution
A gravity acceleration measurement apparatus and method utilizing a three-axis gravity accelerometer, a reference measurement sensor, and a temperature sensor, along with a measurement circuit that performs cross-correlation and digital filtering to suppress interference signals, allowing for accurate extraction of gravity acceleration in a rotating state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drilling tool rotates continuously for dynamic measurement, then the measurement frequency and drilling efficiency are improved, but the measurement accuracy deteriorates due to interference from centrifugal, vibration, and shock accelerations
Solution Approach 1:
The patent converts the harmful interference signals (centrifugal acceleration, vibration acceleration, shock acceleration) into useful information by using cross-correlation processing with reference signals. The reference signals generated by rotation are correlated with the accelerometer outputs to identify and extract the gravity acceleration component from the mixed signals, thereby transforming the harmful rotating environment into a beneficial dynamic measurement condition.
Solution Approach 2:
The patent introduces reference measurement sensors (such as magnetometers or encoders) as intermediaries to generate reference signals that represent the rotation state. These reference signals serve as mediators to correlate with the accelerometer outputs, enabling the separation of gravity acceleration from interference signals without requiring the drilling tool to stop.
2Measurement precision
If the drilling tool stops for measurement, then the measurement accuracy is improved by reducing interference, but the drilling efficiency and productivity deteriorate
Solution Approach 1:
The patent transitions from static measurement (requiring drill stop) to dynamic measurement (continuous rotation). The measurement system is designed to operate accurately during rotation by using cross-correlation processing to extract gravity acceleration from the dynamic signals, allowing continuous drilling without stopping while maintaining measurement accuracy.
Solution Approach 2:
The patent enables continuous measurement during continuous drilling operation. The cross-correlation processing method allows gravity acceleration to be extracted from accelerometer signals even during rotation, eliminating the need to stop drilling for measurement and maintaining continuous productive action throughout the measurement process.
3Device complexity
If intermittent measurement is performed every 30 meters, then the measurement system complexity is reduced, but the well trajectory control accuracy deteriorates
Solution Approach 1:
The patent replaces the mechanical approach of stopping and starting the drill for measurement with a signal processing approach. Cross-correlation processing and digital filtering methods are used to extract gravity acceleration from continuous dynamic signals, providing high-resolution measurement data without increasing mechanical system complexity.
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 dynamic and continuous measurement of well trajectory, improving measurement accuracy and drilling efficiency by effectively filtering out interference from rotation, vibration, and shock, thus enhancing the precision of inclination and toolface angle calculations.
Implementation Method 1
the sensors include a three-axis gravity accelerometer, a reference measurement sensor and a temperature sensor, the three-axis gravity accelerometer measures acceleration component signals in three mutually orthogonal directions
Implementation Method 2
the measurement circuit acquires output signals of the sensors, respectively performs cross-correlation processing on the acceleration component signals subjected to the temperature compensation by using the reference signal, and eliminates centrifugal acceleration, vibration, shock and other interferences generated by rotation
Implementation Method 3
the measurement circuit includes an analog-to-digital converter, a low-pass filter, a memory, a microcontroller and a data interface; the low-pass filter performs filtering on the acceleration component signals after the temperature compensation is performed
Implementation Method 4
the temperature sensor measures temperature in the apparatus and the temperature is used for compensating the temperature effect of the gravity accelerometers and eliminating the temperature influence in downhole environment on the gravity accelerometers
Data Source
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AI summary
The present invention provides a gravity acceleration measurement apparatus and extraction method in a rotating state. The apparatus comprises sensors and a measurement circuit, the sensors comprise a three-axis gravity accelerometer, a reference measurement sensor and a temperature sensor, the three-axis gravity accelerometer measures acceleration component signals in three mutually orthogonal directions, and the reference measurement sensor generates a signal that varies with rotation and is not affected by vibration or shock to serve as a reference signal; the temperature sensor measures the temperature in the apparatus and is used for compensating the temperature effect of the gravity accelerometers; and the measurement circuit acquires output signals of the sensors, respectively performs cross-correlation processing on the accelerometer components by using the reference signal to extract gravity acceleration signals so as to eliminate centrifugal acceleration, vibration, shock and other interferences generated by rotation, and the non-interference gravity acceleration signals are obtained according to the measurement method which can be used for calculating an inclination angle and a toolface angle of a drilling tool in the rotating state.