At-bit magnetic ranging and surveying

摘要

A bottom hole assembly configured for a subterranean drilling operation having a drill bit; a downhole tool deployed above the drill bit, at least a portion of the downhole tool free to rotate with respect to the drill bit about a longitudinal axis of the bottom hole assembly a sensor sub deployed axially between the drill bit and the downhole tool, the sensor sub configured to rotate with the drill bit about the longitudinal axis of the bottom hole assembly and free to rotate with respect to the downhole tool about the longitudinal axis and a tri-axial magnetic field sensor deployed in the sensor sub.

主权项

1. A method for making at bit magnetic ranging measurements in a subterranean borehole, the method comprising:
(a) rotating a bottom hole assembly in the subterranean borehole, the bottom hole assembly including a magnetic field sensor in sensory range of at least first and second sources of bottom hole assembly magnetic interference, the first source being rotationally coupled to the magnetic field sensor and the second source free to rotate about a longitudinal axis of the bottom hole assembly with respect to the magnetic field sensor; (b) measuring a magnetic field with the magnetic field sensor; (c) removing first and second magnetic interference components from the measurement made in (b) to obtain a residual magnetic field, the first magnetic interference component emanating from the first source and the second magnetic interference component emanating from the second source; and (d) processing the residual magnetic field obtained in (c) to determine at least one of a distance and a direction to a remote magnetic source.