Patent ID: 11965408
Assignee: VECTOR MAGNETICS, LLC
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 7:
8. A method of calibrating an at bit inclination and azimuth tool connected to a rotatable drill bit of a downhole drilling assembly, the method comprising:
placing the at bit inclination and azimuth tool connected to the rotatable drill bit on roller supports connected to a rotatable platform at a borehole site;
leveling the rotatable platform such that a z-axis of the at bit inclination and azimuth tool and rotatable drill bit is level and points along magnetic north;
rotating the at bit inclination and azimuth tool and rotatable drill bit about a vertical axis of the at bit inclination and azimuth tool;
recording azimuth and z magnetometer sensor measurements from the at bit inclination and azimuth tool;
returning the z-axis of the at bit inclination and azimuth tool to an orientation of magnetic north;
with the z-axis fixed, rolling the at bit inclination and azimuth tool about the z-axis and record x and y magnetometer sensor measurements and a roll angle; and
calculating multipliers for calibration x magnetic field component, calibration y magnetic field component and calibration z magnetic field component and calibration remanent magnetic field components associated with the at bit inclination and azimuth tool and drill bit and storing in a repository.