External Hollow Antenna

• US 20160356146A1
• Filed: 06/08/2015
• Published: 12/08/2016
• Est. Priority Date: 06/06/2014
• Status: Active Grant

• Current Assignee: Charles Machine Works Incorporated The
• Original Assignee: Charles Machine Works Incorporated The
• Inventors: Gard, Michael F., Bailey, Brian K., Sharp, Richard F.
• Granted Patent: US 9,995,132 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 7/046 horizontal drilling drilling with mechanical conveying means E21B7/003
• CPC Class Codes: H01Q 1/04 Adaptation for subterranean or subaqueous use
• CPC Class Codes: H01Q 1/42 Housings not intimately mechanically associated with radiating elements, e.g. radome
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A beacon assembly located at a downhole end of a drill string proximate a boring tool. The beacon assembly transmits data to an above-ground receiver. The beacon has a housing with a housing wall located between its sensors, such as gradiometers, accelerometers, and other orientation sensors, and an antenna assembly. The antenna assembly has a protective covering made of electromagnetically transparent material.

Claims

1. A beacon assembly for attachment to a downhole end of a drill string, the beacon assembly comprising:

a housing wall;

a sensor located within the housing wall;

a coil electronically connected to the at least one sensor, the coil disposed outside of and about the housing wall.

2. The beacon assembly of claim 1 further comprising a plurality of ferrite rods located between the coil and the housing wall.

3. The beacon assembly of claim 1 further comprising:

an electromagnetically transparent protective casing located about the coil;

a conductive, non-magnetic shield disposed between the housing wall and the coil; and

a non-conductive, non-magnetic tube disposed between the shield and the coil.

4. The beacon assembly of claim 3 wherein the electromagnetically transparent layer comprises ceramics.

5. The beacon assembly of claim 1 wherein the housing wall has a varying diameter.

6. The beacon assembly of claim 1 wherein the sensor is an orientation sensor.

7. A beacon assembly for attachment to a downhole end of a drill string, the drill string comprising a substantially constant first diameter, the beacon assembly comprising:

a housing wall comprising a first portion and a second portion, wherein the first portion has substantially the first diameter, and the second portion has a second diameter, wherein the second diameter is less than the first diameter;

an antenna located about the second portion of the housing wall; and

a sensor located within the housing wall in electronic communication with the antenna.

8. The beacon assembly of claim 7 further comprising a protective casing disposed about the antenna.

9. The beacon assembly of claim 8 wherein the protective casing has substantially the first diameter.

10. The beacon assembly of claim 7 wherein the sensor is located within the first portion of the housing wall.

11. The beacon assembly of claim 7 wherein the antenna comprises a coil and a plurality of ferrite rods disposed between the coil and the housing wall.

12. The beacon assembly of claim 7 wherein the housing wall further comprises a transition shoulder between the first portion and the second portion, wherein the antenna is connected to the sensor through the transition shoulder.

13. A downhole tool coupled to a drill string comprising:

a sensor;

an antenna electronically connected to the sensor;

a wall disposed between the antenna and the sensor, the wall comprising a connection point for connection to the drill string;

a conductive, non-magnetic shield disposed between the wall and the antenna; and

a non-conductive, non-magnetic tube disposed between the shield and the antenna.

14. The downhole tool of claim 13 wherein the antenna comprises a coil and a plurality of ferrite rods disposed between the coil and the wall.

15. The downhole tool of claim 14 wherein the sensor is disposed within the coil and within the wall.

16. The downhole tool of claim 13 wherein the sensor comprises an orientation sensor.

17. The downhole tool of claim 13 wherein the wall comprises a first portion and a second portion, wherein the first portion has a greater diameter than the second portion and wherein the sensor is located within the first portion and the antenna coil is disposed about the second portion.

18. The downhole tool of claim 13 further comprising a protective shell disposed about the antenna.

19. The downhole tool of claim 13 further comprising a generator driven by the drill string for powering the antenna assembly.

20. The downhole tool of claim 13 further comprising an insulating gap between the shield and the wall.