Claims
- 1. A magnet assembly for nuclear magnetic well logging apparatus, comprising:two diametrically opposed magnets, each magnet having a magnet axis and being partitioned into a first and a second magnet segment along a plane substantially parallel to each magnet axis, the first and second magnet segments having a first and a second magnetization angle whereby a magnetic field of each magnet segment for each diametrically opposed magnets combine to produce a static, non-axisymmetric along a longitudinal axis of the logging apparatus, and substantially homogeneous magnetic field in a resonance region.
- 2. The magnet assembly of claim 1, wherein each magnet segment is elongated in a direction along the magnet axis.
- 3. The magnet assembly of claim 1, wherein a magnetization angle of the first magnet segments in a plane transverse to the magnet axis is different from a magnetization angle of the second magnet segments in the same plane.
- 4. The magnet assembly of claim 3, wherein the magnetization angle of the first segments is in a direction away from the center of the magnet assembly and the magnetization angle of the second segments is in a direction toward the center of the magnet assembly.
- 5. The magnet assembly of claim 4, wherein the magnetization angle of the first segments is in a direction substantially perpendicular to the center of the magnet assembly.
- 6. The magnet assembly of claim 1, wherein the magnets comprise permanent magnets.
- 7. A magnet assembly for nuclear magnetic well logging apparattus, comprising:two diametrically opposed magnets, each magnet having a magnet axis and being partitioned into a first and a second magnet segment along a plane substantially parallel to the magnet axis, that produce a static, non-axisymmetric, and substantially homogeneous magnetic field; wherein the magnetization angle of the first magnet segments in a plane transverse to the magnet axis is different from the magnetization angle of the second magnet segments in the same plane.
- 8. A magnet assembly for nuclear magnetic well logging apparatus, comprising:two diametrically opposed magnets, each magnet having a magnet axis and being partitioned into a first and a second magnet segment along a plane substantially parallel to each magnet axis, the first and second magnet segments having a first and a second magnetization angle respectively whereby a magnetic field of each magnet segment for each diametrically opposed magnets combine to produce a static, non-axisymmetric along a longitudinal axis of the logging apparatus, and substantially homogeneous magnetic field in a resonance region; wherein the first magnetization angle is different from the second magnetization angle.
- 9. The nuclear magnetic resonance well logging apparatus of claim 8, wherein each magnet segment is elongated in a direction along the magnet axis.
- 10. The nuclear magnetic resonance well logging apparatus of claim 8, wherein a magnetization angle of the first magnet segments in a plane transverse to the magnet axis is different from a magnetization angle of the second magnet segments in the same plane.
- 11. The nuclear magnetic resonance well logging apparatus of claim 10, wherein the magnetization angle of the first segments is in a direction away from the center of the magnet assembly and the magnetization angle of the second segments is in a direction toward the center of the magnet assembly.
- 12. The nuclear magnetic resonance well logging apparatus of claim 11, wherein the magnetization angle of the first segments is in a direction substantially perpendicular to the center of the magnet assembly.
- 13. The nuclear magnetic resonance well logging apparatus of claim 8, wherein the magnets comprise permanent magnets.
- 14. A nuclear magnetic resonance well logging apparatus including a tool body adapted for longitudinal movement in a borehole, the apparatus comprising:two diametrically opposed magnets disposed within a cavity in the tool body, each magnet having a magnet axis substantially aligned with the longitudinal axis of the borehole, the magnets producing a static, non-axisymmetric along a longitudinal axis of the logging apparatus, and substantially homogeneous magnetic field in a resonance region in a volume of formation directed to one side of the tool body, each magnet being partitioned into a first and a second magnet segment along a plane substantially parallel to each magnet axis, the first and second magnet segments having a first and a second magnetization angle; an antenna disposed external to the tool body; wherein the first magnetization angle is different from the second magnetization angle.
- 15. A magnet assembly for nuclear magnetic well logging apparatus, comprising:two diametrically opposed magnets, each magnet having a magnet axis and being partitioned into a first and a second magnet segment along a plane transverse to each magnet axis, the first and second magnet segments having a first and a second magnetization angle whereby a magnetic field of each magnet segment for each diametrically opposed magnets combine to produce a static, non-axisymmetric along a longitudinal axis of the logging apparatus, and substantially homogeneous magnetic field in a resonance region.
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority from provisional application serial No. 60/143,382, filed Jul. 12, 1999.
US Referenced Citations (8)
Number |
Name |
Date |
Kind |
4717876 |
Masi et al. |
Jan 1988 |
A |
4717877 |
Taicher et al. |
Jan 1988 |
A |
5055788 |
Kleinberg et al. |
Oct 1991 |
A |
5376884 |
Sezginer |
Dec 1994 |
A |
5432446 |
MacInnis et al. |
Jul 1995 |
A |
5486761 |
Sezginer |
Jan 1996 |
A |
6348792 |
Beard et al. |
Feb 2002 |
B1 |
6362619 |
Prammer et al. |
Mar 2002 |
B2 |
Non-Patent Literature Citations (1)
Entry |
D. Mckeon, An Improved NMR Tool Design for Faster Logging, May 30, 1999, SPWLA 40th Annual Logging Symposium, pp. 1-14. |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/143382 |
Jul 1999 |
US |