Steerable magnetic dipole antenna for measurement while drilling applications

摘要

A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna.

主权项

1. An antenna for creating or detecting a magnetic field substantially perpendicular to the major axis of a substantially cylindrical tool; said antenna comprising:
an essentially round hole disposed in a wall of said tool on a chord in a plane perpendicular to said major axis of said tool, said hole having first and second ends at an outer surface of said tool; a ferromagnetic rod disposed within said hole; non-conducting inserts terminating each end of said hole; a slit extending radially outward with respect to said hole between said hole and an outer surface of said tool; and an antenna wire essentially parallel to said major axis of said tool and traversing said slit perpendicular to said slit.