Systems and methods for directional drilling

Patent metadata

Field	Value
Publication number	US-10072461-B1
Application number	US-201715645242-A
Country	US
Kind code	B1
Filing date	Jul 10, 2017
Priority date	Apr 1, 2016
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

An underground directional drilling system can comprise a plurality of elongated dual-shaft segments coupled together end-to-end and forming an inner shaft assembly independently rotatable relative to an annular outer shaft assembly. The dual-shaft drilling system can include a communication segment that comprises an outer shaft having first longitudinal portion, a second longitudinal, and a gap portion that provides electrical insulation therebetween. The communication segment can generate voltage differences between the longitudinal portions that cause electrical pulses to periodically transfer across the gap portion to wirelessly communicate drilling related data to the surface. An inner shaft of the communication segment can comprise electrical insulation to avoid creating an electrical short between the first and second longitudinal portions of the outer shaft. The inner shaft assembly can further comprise various sensors, electronics, and communication components, such as a magnetic sensor system that determines relative rotational orientations between the inner and outer shaft assemblies.

First claim

The invention claimed is:

1. A dual-shaft underground directional drilling system, comprising:
an inner shaft assembly, and an outer shaft assembly positioned around the inner shaft assembly, such that the inner and outer shaft assemblies are rotatable independently of each other;
wherein the outer shaft assembly comprises a communication segment having a first electrode portion, a second electrode portion, and a gap portion between the first and second electrode portions that provides electrical insulation between the first and second electrode portions;
wherein the system produces a voltage difference between the first and second electrode portions of the communication segment sufficient to cause an electrical pulse to transfer from one of the first and second electrode portions, through the gap portion, and to the other of the first and second electrode portions;
wherein the system 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; and wherein the inner shaft assembly comprises a fluid bypass segment having an inner lumen and two axially spaced part radial conduits fluidly coupling the inner lumen to an annular passageway between the inner shaft assembly and the outer shaft assembly.

2. The system of claim 1 , wherein the outer shaft assembly comprises a bearing segment positioned around the fluid bypass segment of the inner shaft assembly, the bearing segment comprising a bearing bore that fits closely around an outer surface of the fluid bypass segment, the bearing boring positioned axially between the two axially spaced part radial conduits of the fluid bypass segment, such that fluid in the annular passageway can bypass the bearing bore by traveling through the inner lumen of the fluid bypass segment.

3. The system of claim 2 , wherein a close fit between the outer surface of the fluid bypass segment and the bearing bore of the bearing segment provides both a mechanical limitation to control a radial position of the inner shaft assembly within the outer shaft assembly and an electrical connection between the inner shaft assembly and the outer shaft assembly.

4. The system of claim 2 , wherein the bearing segment comprises a proximal portion, including the bearing bore having a first inner diameter, and a distal portion having a second inner diameter that is greater than the first inner diameter, and wherein a portion of the annular passageway is formed between the outer surface of the fluid bypass segment and the distal portion of the bearing segment.

5. The system of claim 4 , wherein the inner lumen of the fluid bypass segment extends entirely through the proximal portion and into the distal portion, and wherein a first of the two axially spaced part radial conduits is positioned within the distal portion of the bearing segment.

6. A dual-shaft underground directional drilling system, comprising:
an inner shaft assembly, and an outer shaft assembly positioned around the inner shaft assembly, such that the inner and outer shaft assemblies are rotatable independently of each other;
wherein the outer shaft assembly comprises a communication segment having a first electrode portion, a second electrode portion, and a gap portion between the first and second electrode portions that provides electrical insulation between the first and second electrode portions;
wherein the system produces a voltage difference between the first and second electrode portions of the communication segment sufficient to cause an electrical pulse to transfer from one of the first and second electrode portions, through the gap portion, and to the other of the first and second electrode portions;
wherein the system 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;
wherein the outer shaft assembly further comprises a magnet holding segment including one or more magnetic devices; and
wherein the inner shaft assembly further comprises a magnetic sensor module configured to sense circumferential positioning of the one or more magnetic devices to determine a rotational orientation of the inner shaft assembly relative to the outer shaft assembly.

7. The system of claim 6 , wherein the one or more magnetic devices comprises two screw assemblies mounted in a radial wall of the magnet holding segment.

8. The system of claim 7 , wherein the two screw assemblies each comprise a metal screw portion and a magnet portion.

9. The system of claim 6 , wherein the one or more magnetic devices comprises two disk shaped magnets mounted in a radial wall of the magnet holding segment.

10. The system of claim 6 , wherein the one or more magnetic devices comprise two magnets that have the same polarity and are located at two discrete circumferential positions around the magnet holding segment.

11. The system of claim 6 , wherein the magnet holding segment is comprised of non-magnetic materials, except for the one or more magnetic devices, to avoid interfering with the magnetic sensor module sensing circumferential positioning of the one or more magnetic devices.

12. The system of claim 6 , further comprising a drilling head at a distal end of the system, wherein the magnet holding segment and the magnetic sensor system are positioned axially between the communication segment and the drilling head.

13. The system of claim 12 , further comprising an orientation sensor that measures the direction of gravity relative to an axial direction of the drilling system at a location adjacent the drilling head, such that the system is capable of determining absolute rotational and directional orientations of the inner and outer shaft assemblies adjacent the drilling head based on outputs from the magnetic sensor module and the orientation sensor.

Assignees

• Savant Tech Llc

Inventors

• Hogan Thomas S

Classifications

• E21B7/06 Primary

  Deflecting the direction of boreholes · CPC title

• E21B47/12

  Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling · CPC title

• E21B47/09 Primary

  Locating or determining the position of objects in boreholes or wells {, e.g. the position of an extending arm}; Identifying the free or blocked portions of pipes · CPC title

• E21B17/003

  with electrically conducting or insulating means (E21B17/028 and E21B17/023 take precedence) · CPC title

• E21B7/04

  Directional drilling · CPC title