Stacked soft magnetic inserts and slotted shield designs for titled coil antennas

Patent metadata

Field	Value
Publication number	US-11320559-B2
Application number	US-201716462162-A
Country	US
Kind code	B2
Filing date	Jan 10, 2017
Priority date	Jan 10, 2017
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

An antenna assembly includes a tool mandrel having a tool axis, and a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis. A soft magnetic band radially interposes the coil and the tool mandrel and extends about a circumference of the tool mandrel at a band angle parallel to the winding angle. The soft magnetic band includes a plurality of stacked inserts extending perpendicular to the coil about the circumference of the tool mandrel and each stacked insert includes a plurality of rods positioned end-to-end.

First claim

What is claimed is:

1. An antenna assembly, comprising:
a tool mandrel having a tool axis;
a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis; and
a soft magnetic band radially interposing the coil and the tool mandrel and extending about a circumference of the tool mandrel at a band angle parallel to the winding angle,
wherein the soft magnetic band includes a plurality of stacked inserts extending perpendicular to the coil about the circumference of the tool mandrel and each stacked insert includes a plurality of rods positioned end-to-end, the soft magnetic band configured to increase an inductance of the coil.

2. The antenna assembly of claim 1 , wherein the plurality of rods comprises a material selected from the group consisting of a ferrite, mu-metal, permalloy, metallic glass, and any combination thereof.

3. The antenna assembly of claim 1 , wherein the soft magnetic band interposes the coil and the tool mandrel about the entire circumference of the tool mandrel.

4. The antenna assembly of claim 1 , wherein the plurality of rods in each stacked insert cooperatively forms a corresponding straight stacked insert that follows a curvature of an outer surface of the tool mandrel while extending perpendicular to the coil.

5. The antenna assembly of claim 1 , wherein at least one rod of the plurality of rods has a length that is dissimilar to a length of other rods of the plurality of rods.

6. The antenna assembly of claim 1 , wherein each rod comprises a straight, cylindrical member that exhibits a circular or polygonal cross-section.

7. The antenna assembly of claim 1 , further comprising a bobbin positioned about the circumference of the mandrel, wherein the plurality of stacked inserts is positioned on the bobbin.

8. The antenna assembly of claim 1 , wherein the plurality of stacked inserts is positioned on an outer radial surface of the bobbin.

9. The antenna assembly of claim 8 , wherein the plurality of stacked inserts is positioned on an inner radial surface the bobbin.

10. The antenna assembly of claim 1 , further comprising an antenna shield secured to the tool mandrel and positioned radially outward from the coil, wherein the antenna shield defines a plurality of slots extending perpendicular to the coil at any angular location about the circumference of the tool mandrel.

11. The antenna assembly of claim 9 , wherein the plurality of slots is provided in two or more dissimilar lengths.

12. The antenna assembly of claim 9 , wherein the plurality of stacked inserts are aligned radially with the plurality of slots.

13. The antenna assembly of claim 9 , wherein the plurality of stacked inserts are radially misaligned with the plurality of slots.

14. A method, comprising:
introducing a wellbore logging tool into a wellbore, the wellbore logging tool including an antenna assembly that includes:
a tool mandrel having a tool axis;
a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis; and
a soft magnetic band radially interposing the coil and the tool mandrel and extending about a circumference of the tool mandrel at a band angle parallel to the winding angle, wherein the soft magnetic band includes a plurality of stacked inserts extending perpendicular to the coil about the circumference of the tool mandrel and each stacked insert includes a plurality of rods positioned end-to-end, the soft magnetic band configured to increase an inductance of the coil; and

obtaining measurements of a surrounding subterranean formation with the wellbore logging tool.

15. The method of claim 14 , wherein the tool mandrel is operatively coupled to a drill string and introducing the wellbore logging tool into the wellbore further comprises:
extending the wellbore logging tool into the wellbore on the drill string; and
drilling a portion of the wellbore with a drill bit secured to a distal end of the drill string.

16. The method of claim 14 , wherein introducing the wellbore logging tool into the wellbore further comprises extending the wellbore logging tool into the wellbore on wireline as part of a wireline instrument sonde.

17. The method of claim 14 , wherein the antenna assembly further includes a bobbin arranged about the circumference of the mandrel and the plurality of stacked inserts is positioned on the bobbin.

18. The method of claim 14 , wherein the antenna assembly further includes an antenna shield secured to the tool mandrel and positioned radially outward from the coil, wherein the antenna shield defines a plurality of slots extending perpendicular to the coil at any angular location about the circumference of the tool mandrel.

19. The method of claim 18 , wherein the plurality of slots is provided in two or more dissimilar lengths.

20. The method of claim 18 , wherein the plurality of stacked inserts are aligned or misaligned radially with the plurality of slots.

Assignees

• Halliburton Energy Services Inc

Inventors

• Bittar Michael
• Ma Jin
• Wu Hsu-Hsiang

Classifications

• E21B47/00

  Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) · CPC title

• H01Q1/46

  Electric supply lines or communication lines · CPC title

• H01Q1/44

  using equipment having another main function to serve additionally as an antenna {, e.g. means for giving an antenna an aesthetic aspect}(H01Q1/27 - H01Q1/34 take precedence) · CPC title

• G01V3/26

  operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30) · CPC title

• H01Q7/06

  with core of ferromagnetic material (H01Q7/02 takes precedence) · CPC title