Method and apparatus for indicating the position of one well bore with respect to a second well bore

摘要

A compression wave type signal of a selected frequency is transmitted into the ground at the bottom of a well bore being drilled. The signal is picked up by four microphones that are positioned in another well bore. The microphones have a known orientation with respect to the desired course of the well bore being drilled. The phase relationship of the transmitted signal picked up by the microphones is used to indicate at the surface the deviation between the course of the well being drilled and the desired course.