CPC E21B 7/04 (2013.01) [E21B 47/04 (2013.01); E21B 47/13 (2020.05); G01C 19/00 (2013.01); G01D 5/14 (2013.01)] | 20 Claims |
1. A magnetic ranging system for use with a drilling assembly in a borehole in a formation, the drilling assembly including a drill string, a drill bit and a bottomhole assembly (BHA) connected to the drill bit, the magnetic ranging system comprising:
first and second gradient magnetometer arrays incorporated into the BHA and each having three cross-axis coplanar tri-axial magnetometers evenly spaced around an axis of the BHA to define a cross-borehole plane, wherein the first and second gradient magnetometer arrays are configured to collect ranging measurements from behind the drill bit and transmit measurement data;
an injection electrode configured to inject current into the formation; and
a return electrode above the injection electrode, wherein at least one of the first and second gradient magnetometer arrays are below the injection and return electrodes.
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