Gravity Toolface Azimuth via Accelerometer Gyroscope Sensor Fusion
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Solution Overview
Problem
Existing methods for calculating the gravity toolface azimuth in wellbores, particularly in cased holes, face interference issues due to metal casing distortion of the earth's magnetic field, leading to inaccurate measurements.
Innovation Solution
A system utilizing a logging tool equipped with an accelerometer and an angular gyroscope to determine the gravity toolface azimuth by processing sensor data, eliminating the need for magnetometers and thereby avoiding interference from metal casings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometers are used to determine toolface azimuth in cased holes, then the measurement can be obtained, but the metal casing distorts the earth's magnetic field causing inaccurate measurements
Solution Approach 1:
The patent removes magnetometers from the tool assembly and replaces them with accelerometers and gyroscopes. This extraction eliminates the harmful interaction between magnetometers and metal casing, allowing accurate toolface azimuth measurement in cased holes without magnetic field distortion
Solution Approach 2:
The patent substitutes magnetic field-based measurement (magnetometers) with mechanical/inertial-based measurement (accelerometers and gyroscopes). The accelerometer measures gravitational acceleration to determine toolface orientation, while the gyroscope measures angular velocity, replacing the magnetic field interaction with mechanical sensing that is immune to metal casing interference
2Loss of information
If gyroscopes and magnetometers are used together to determine azimuth and toolface, then more comprehensive data is obtained, but magnetic interference from casing still affects accuracy
Solution Approach 1:
The patent extracts and removes the magnetometer component from the sensor suite, eliminating its susceptibility to magnetic interference while retaining the gyroscope for azimuth measurement and adding the accelerometer for toolface determination, achieving both data completeness and accuracy
Solution Approach 2:
The patent changes the physical parameters measured by the sensor system from magnetic field parameters (magnetometer readings) to mechanical parameters (accelerometer and gyroscope readings). This parameter change allows the system to maintain comprehensive azimuth and toolface data while being immune to magnetic field distortion
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 provides accurate and interference-free calculations of the gravity toolface azimuth, resulting in high-resolution imagery and improved logging data quality in both cased and open hole portions of the wellbore.
Implementation Method 1
positioning an accelerometer sensor within the logging tool at a first radial distance from the center axis; determining, via the controller, a radial acceleration component of the accelerometer sensor from the accelerometer sensor data
Implementation Method 2
positioning an angular gyroscope sensor within the logging tool at a second radial distance from the center axis; determining, via the controller, the gravity toolface azimuth of the logging tool as a function of time based on the gain, the offset, and the angular gyroscope sensor data
Data Source
AI summary
A method for determining gravity toolface azimuth that can include rotating a logging tool about a center axis; positioning an accelerometer sensor within the logging tool at a first radial distance from the center axis; positioning an angular gyroscope sensor within the logging tool at a second radial distance from the center axis; receiving, at a controller, accelerometer sensor data from the accelerometer sensor and angular gyroscope sensor data from the angular gyroscope sensor as the logging tool rotates; determining, via the controller, a radial acceleration component of the accelerometer sensor from the accelerometer sensor data; determining, via the controller, a gain and an offset of the angular gyroscope sensor based on the radial acceleration component; and determining, via the controller, the gravity toolface azimuth of the logging tool as a function of time based on the gain, the offset, and the angular gyroscope sensor data.