Electromagnetic insulating component used in well logging tool pad

Patent metadata

Field	Value
Publication number	US-11333787-B2
Application number	US-201816613783-A
Country	US
Kind code	B2
Filing date	Dec 28, 2018
Priority date	Dec 28, 2018
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

A downhole tool, comprising: a tool mandrel; a pad comprising a transmitter operable to transmit an electric current into a formation and a receiver operable to receive at least a portion of the electric current from transmitter; an extension from the tool mandrel that couples pad to tool mandrel; and a signal filter positioned in the downhole tool to suppress passage of mandrel leakage current that passes through tool mandrel to pad. A method of resistivity imaging, comprising: disposing a downhole tool into borehole; transmitting a current into formation surrounding the borehole with a transmitter that is extended from tool mandrel of the downhole tool towards borehole wall; and recording at least a portion of the current that returns to receiver of downhole tool, wherein a signal filter suppress passages of mandrel leakage current that passes through the tool mandrel to a pad on which the transmitter is disposed.

First claim

What is claimed is:

1. A downhole tool, comprising:
a tool mandrel;
a pad comprising a transmitter operable to transmit an electric current into a formation and a receiver operable to receive at least a portion of the electric current from the transmitter;
an extension from the tool mandrel that couples the pad to the tool mandrel; and
a signal filter positioned in the downhole tool to suppress passage of a leak current that passes first through the formation, through the tool mandrel, and then to the pad.

2. The downhole tool of claim 1 , wherein the signal filter comprises a soft magnetic material.

3. The downhole tool of claim 1 , wherein the signal filter comprises at least one soft magnetic material selected from the group consisting of a ferrite, iron, iron-silicon alloy, nickel-iron alloy, iron-aluminum alloy, iron-cobalt alloy, low-carbon steel, iron-aluminum-silicon alloy, amorphous alloy, and any combination thereof.

4. The downhole tool of claim 3 , wherein the soft magnetic material comprises the ferrite.

5. The downhole tool of claim 1 , wherein the signal filter comprises a soft magnetic material having a relative permeability of about 20 or greater.

6. The downhole tool of claim 1 , wherein the signal filter comprises a sleeve at least partially wrapped around the extension, wherein the extension comprises an arm that is extendable from the tool mandrel.

7. The downhole tool of claim 6 , wherein the sleeve is disposed completely around a diameter of the arm.

8. The downhole tool of claim 1 , wherein the signal filter comprises a choke at least partially wrapped around the tool mandrel.

9. The downhole tool of claim 1 , wherein the signal filter is in the form of a sleeve, choke, or a wrap.

10. The downhole tool of claim 1 , wherein the receiver comprises a pair of return electrodes, and wherein the transmitter comprises an array of injection electrodes.

11. The downhole tool of claim 1 , further comprising a plurality of pads, wherein each of the pads is coupled to the tool mandrel by one or more extensions, wherein each of the pads comprises a transmitter and a receiver.

12. The downhole tool of claim 1 , wherein the downhole tool is operable to transmit the electric current into the formation at a high frequency of from about 10 kHz to about 1 GHz.

13. A downhole tool, comprising:
a tool mandrel;
a pad comprising an array of injection electrodes and a pair of return electrodes, wherein each of the return electrodes are disposed on opposite sides of the array from one another;
an arm that couples the pad to the tool mandrel, wherein the arm is extendable from the tool mandrel;
a ferrite sleeve disposed on the arm; and
a signal filter positioned in the downhole tool to suppress passage of a leak current that passes first through the formation, through the tool mandrel, and then to the pad.

14. The downhole tool of claim 13 , wherein the ferrite sleeve has a relative permeability of about 20 or greater.

15. The downhole tool of claim 13 , wherein the ferrite sleeve is disposed completely around a diameter of the arm.

16. The downhole tool of claim 13 , further comprising a plurality of pads, wherein each of the pads is coupled to the tool mandrel by one or more extensions, wherein each of the pads comprises a transmitter and a receiver.

17. A method of resistivity imaging, comprising:
disposing a downhole tool into a borehole;
transmitting a current into a formation surrounding the borehole with a transmitter that is extended from a tool mandrel of the downhole tool towards a borehole wall; and
recording at least a portion of the current that returns to a receiver of the downhole tool, wherein a signal filter positioned in the downhole tool to suppress passage of a leak current that passes first through the formation, through the tool mandrel, and then to a pad.

18. The method of claim 17 , further comprising extending the pad from the downhole tool with an arm, wherein the transmitter transmits the current when the pad is in engagement with a mudcake formed on the borehole wall, wherein an oil- or synthetic-based drilling mud is disposed in the borehole, and wherein the formation has a resistivity from about 0.01 Ω-m to about 1 Ω-m.

19. The method of claim 18 , wherein the signal filter is disposed on the arm or the tool mandrel, wherein the signal filter comprises a soft magnetic material having a relative permeability of about 20 or greater.

20. The method of claim 17 , further comprising extending the pad from the downhole tool with an arm wherein the signal filter is in the form of a sleeve disposed on the arm.

Assignees

• Halliburton Energy Services Inc

Inventors

• Dai Junwen
• Donderici Burkay
• Beard David Ronald

Classifications

• 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

• G01V11/005

  Devices for positioning logging sondes with respect to the borehole wall (centralising devices for drilling rods or pipes E21B17/10; setting or locking tools in boreholes E21B23/00; locating objects in boreholes E21B47/09) · CPC title

• E21B47/0025 Primary

  generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric · CPC title

• G01V3/30

  operating with electromagnetic waves · CPC title

• E21B47/00 Primary

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