Abstract: An example method of calibrating a downhole tool includes stimulating a known current through a power circuit provided in the downhole tool, the power circuit extending between and communicably coupling a power source and a load. A conductor magnetic field is generated as the known current flows through the power circuit and the conductor magnetic field is detectable by a magnetic sensor included in the downhole tool to obtain sample measurements of Earth's magnetic field. A magnitude of the conductor magnetic field is then measured to obtain a measured value for the conductor magnetic field, and a relationship between the known current and the measured value is determined to calculate a correction factor for the sample measurements based on the relationship. A computer in the downhole tool is then programmed to apply the correction factor to the sample measurements in response to operational currents measured in the power circuit during operation.

Abstract: An example method of calibrating a downhole tool includes stimulating a known current through a power circuit provided in the downhole tool, the power circuit extending between and communicably coupling a power source and a load. A conductor magnetic field is generated as the known current flows through the power circuit and the conductor magnetic field is detectable by a magnetic sensor included in the downhole tool to obtain sample measurements of Earth's magnetic field. A magnitude of the conductor magnetic field is then measured to obtain a measured value for the conductor magnetic field, and a relationship between the known current and the measured value is determined to calculate a correction factor for the sample measurements based on the relationship. A computer in the downhole tool is then programmed to apply the correction factor to the sample measurements in response to operational currents measured in the power circuit during operation.