Nuclear magnetic resonance tool with external magnets

Patent metadata

Field	Value
Publication number	US-9841529-B2
Application number	US-201113885453-A
Country	US
Kind code	B2
Filing date	Nov 16, 2011
Priority date	Nov 19, 2010
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

Methods and systems are provided that enable logging while drilling NMR measurements to be made with magnets placed outside of the drill collar and magnetically permeable members to control the magnetic field gradient. A set of magnets can be disposed on and/or embedded on a drill collar, with an antenna disposed axially therebetween. Alternatively, a set of magnets and an antenna disposed therebetween can be disposed on a sleeve that is slid onto a recess in a drill collar. Additionally, a permeable member can be axially positioned between the set of magnets for affecting the depth of investigation.

First claim

What is claimed is:

1. A nuclear magnetic resonance apparatus comprising:
a drill collar with a flow line;
a first magnet embedded in the drill collar;
a second magnet axially separated from the first magnet;
a magnetically permeable member split into three rings wherein the member is disposed within the flow line and wherein the member is positioned between the first magnet and the second magnet; and
an antenna disposed between the first magnet and second magnet.

2. The apparatus of claim 1 , wherein the permeable member comprises a magnetic material.

3. The apparatus of claim 2 , wherein the permeable member further comprises a non-magnetic material.

4. The apparatus of claim 1 , wherein the permeable member comprises a magnetic material to shape a static magnetic field generated by the apparatus.

5. A nuclear magnetic resonance apparatus comprising:
a drill collar having a recess;
a sleeve configured to slide onto the recess;
a first magnet disposed on the sleeve;
a second magnet disposed on the sleeve; and
a magnetically permeable member split into three rings wherein the member is disposed within the flow line and wherein the member is positioned between the first magnet and the second magnet; and
an antenna disposed between the first magnet and second magnet.

6. The apparatus of claim 5 , wherein the flow line is disposed within the drill collar.

7. The apparatus of claim 5 , wherein at least a portion of the permeable member is positioned axially between the first magnet and second magnet.

8. The apparatus of claim 7 , wherein the flow line comprises a magnetic material to shape a static magnetic field generated by the apparatus.

Assignees

• Hopper Timothy
• Oliver David T
• Dementyev Anatoly
• Schlumberger Technology Corp

Inventors

• Hopper Timothy
• Oliver David T
• Dementyev Anatoly

Classifications

• G01V3/32 Primary

  operating with electron or nuclear magnetic resonance · CPC title

• G01R33/3808

  Magnet assemblies for single-sided MR wherein the magnet assembly is located on one side of a subject only; Magnet assemblies for inside-out MR, e.g. for MR in a borehole or in a blood vessel, or magnet assemblies for fringe-field MR · CPC title

• E21B47/00

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