Logging tool ferrites and methods of manufacture

• US 10,222,503 B2
• Filed: 10/20/2015
• Issued: 03/05/2019
• Est. Priority Date: 10/20/2015
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Griffing, Matthew Chase
• Primary Examiner(s): Patel, Vishal I
• Application Number:
  US15/129,580
• Publication Number:
  US 20170261632A1
• Time in Patent Office: 1,232 Days
• CPC Class Codes: G01V 13/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices covered by groups G01V1/00 – G01V11/00
• CPC Class Codes: G01V 3/28 using induction coils
• CPC Class Codes: H01F 1/34 non-metallic substances, e.g. ferrites
• CPC Class Codes: H01F 1/37 in a bonding agent
• CPC Class Codes: H01F 27/28 Coils; Windings; Conductive connections
• CPC Class Codes: H01F 27/325 Coil bobbins formers for coils in general H01F5/02
• CPC Class Codes: H01F 41/02 for manufacturing cores, coils, or magnets H01F41/14 takes precedence; for dynamo-electric machines H02K15/00
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36

Abstract

A method of fabricating a ferrite for use in a resistivity logging tool includes mixing a ferrite powder with a binder to provide a mixture, and pressing the mixture into a mold to form the ferrite. The mold exhibits a specific geometry corresponding to a channel defined on an inner surface of a bobbin associated with the resistivity logging tool, and the channel is arcuate and extends at an angle offset from a central axis of the bobbin. At least one of a length, a width, and a thickness of the ferrite is then adjusted to manipulate a magnetic permeability of the ferrite in a direction of a magnetic field passing through the ferrite.

Claims

1. A method of fabricating a ferrite for use in a resistivity logging tool, comprising:

pressing a mixture of a ferrite powder and a binder into a mold having a geometry corresponding to a channel defined on an inner surface of a bobbin associated with the resistivity logging tool, wherein the channel is arcuate and extends at an angle offset from a central axis of the bobbin; and

adjusting at least one of a length, a width, and a thickness of the ferrite to manipulate a magnetic permeability of the ferrite in a direction of a magnetic field passing through the ferrite.

2. The method of claim 1, wherein the binder is a material selected from the group consisting of a rubber, an elastomer, an epoxy, a polymer, and a ceramic.

3. The method of claim 1, wherein mixing the ferrite powder with the binder comprises rolling the ferrite powder and the binder between adjacent rollers.

4. The method of claim 1, wherein adjusting the at least one of the length, the width, and the thickness of the ferrite comprises increasing an aspect ratio between the length and the width and thereby increasing the magnetic permeability of the ferrite in the direction of the magnetic field passing through the ferrite.

5. The method of claim 4, wherein increasing the aspect ratio between the length and the width comprises at least one of decreasing the width of the ferrite and increasing the length of the ferrite.

6. The method of claim 1, wherein adjusting the at least one of the length, the width, and the thickness of the ferrite comprises increasing an aspect ratio between the length and the thickness and thereby increasing the magnetic permeability of the ferrite in the direction of the magnetic field passing through the ferrite.

7. The method of claim 6, wherein increasing the aspect ratio between the length and the thickness comprises at least one of decreasing the thickness of the ferrite and increasing the length of the ferrite.

8. The method of claim 1, wherein adjusting the at least one of the length, the width, and the thickness of the ferrite comprises positioning at least one lamination between adjacent layers of the ferrite along the length of the ferrite, the at least one lamination being made of a non-magnetic material.

9. The method of claim 8, wherein the non-magnetic material is selected from the group consisting of a polymer, a rubber, an elastomer, an epoxy, a ceramic, and any combination thereof.

10. The method of claim 8, wherein the adjacent layers of the ferrite each exhibit a decreased thickness as compared to the thickness of the ferrite, the method further comprising constraining the magnetic field passing through the ferrite to the decreased thickness of the adjacent layers of the ferrite.