Patent ID: 9702194
Date: 2017-07-11
CPC Classifications: E21B

Claim:
1. A communication segment for a dual-shaft underground directional drilling system, the communication segment comprising: an inner shaft, and an outer shaft positioned around the inner shaft such that the inner and outer shafts are rotatable independently of each other; wherein the inner shaft is configured to be coupled to inner shafts of adjacent segments of a dual-shaft underground directional drilling system such that, when coupled together, the inner shaft can transfer forces between the inner shafts of adjacent segments; wherein the outer shaft is configured to be coupled to outer shafts of adjacent segments of a dual-shaft underground directional drilling system such that, when coupled together, the outer shaft can transfer forces between the outer shafts of adjacent segments; wherein the outer shaft comprises a first longitudinal portion, a second longitudinal portion, and a gap portion between the first and second longitudinal portions that provides electrical insulation between the first and second longitudinal portions; wherein the communication segment is configured to produce a voltage difference between the first and second longitudinal portions of the outer shaft sufficient to cause an electrical pulse to transfer from one of the first and second longitudinal portions, through the gap portion, and to the other of the first and second longitudinal portions; wherein the inner shaft comprises a first end portion, a second end portion, and electrical insulation between the first and second end portions that electrically isolates the first and second end portions, such that the inner shaft provides sufficient electrical resistance between the first and second longitudinal portions of the outer shaft to allow the voltage difference to form; wherein the inner shaft comprises a connector rod having a first axial end that is electrically coupled to the first end portion and a second axial end that is electrically insulated from the second end portion; and wherein the communication segment is configured to produce a plurality of such electrical pulses to wirelessly communicate drilling related data from an underground drilling location to an above ground location.