Boundary tracking control module for rotary steerable systems

A rotary steerable bottom hole assembly comprising:

• a drill bit disposed at a distal end thereof;
• azimuthal resistivity antennas and electronics configured to measure a distance to a formation boundary, the azimuthal resistivity antennas comprising:
• an axial antenna including a wire winding for generating an axial magnetic moment parallel with the longitudinal axis;
• a transverse antenna including an antenna body having a longer axis disposed longitudinally in the housing, and a wire coil having a central axis disposed around the antenna body, wherein the wire coil central axis is substantially perpendicular to the longer axis of the antenna body, and wherein the wire coil is configured to generate a transverse magnetic moment orthogonal to the housing longitudinal axis;
• and
• a stabilizer disposed in the bottom hole assembly uphole from the drill bit;
• wherein the rotary steerable bottom hole assembly further comprises a steerable housing having a longitudinal axis and disposed between the stabilizer and the drill bit, wherein the azimuthal resistivity antennas and electronics are in the housing.