SLOTTED SHIELD FOR LOGGING-WHILE-DRILLING TOOL

• US 20110316542A1
• Filed: 06/29/2010
• Published: 12/29/2011
• Est. Priority Date: 06/29/2010
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Frey, Mark T., Homan, Dean M.
• Application Number:
  US12/825,765
• Publication Number:
  US 20110316542A1
• Time in Patent Office: Days
• US Class Current: 324/339
• CPC Class Codes: G01V 3/26 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

Abstract

An LWD tool with a tubular having a longitudinal axis and a set of co-located antennas carried in a recess on the tubular is disclosed. The tool carries a shield having an open slot configuration and circumferentially surrounds the set of co-located antennas, a first end of the shield being mechanically and electrically connected to the tubular. The tool also includes an insulating ring carried on the tubular, at least a portion of the insulating ring being disposed between the tubular and a second end of the shield.

Claims

1. A downhole while-drilling logging tool, comprising:

a tubular having a longitudinal axis;

a set of co-located antennas carried in a recess on the tubular;

a shield having an open slot configuration and circumferentially surrounding the set of co-located antennas, a first end of the shield being mechanically and electrically connected to the tubular; and

an insulating ring carried on the tubular, at least a portion of the insulating ring being disposed between the tubular and a second end of the shield.

2. The logging tool of claim 1, wherein the logging tool is a toroidal tool, an induction tool, a propagation tool, or a combination of those.

3. The logging tool of claim 1, wherein the tubular is made of non-magnetic metal.

4. The logging tool of claim 1, wherein one or more of the co-located antennas is tilted relative to the longitudinal axis.

5. The logging tool of claim 1, wherein the set of co-located antennas comprises a first coil antenna having a dipole moment substantially parallel to the longitudinal axis, a second coil antenna having a dipole moment substantially perpendicular to the longitudinal axis, and a third coil antenna having a dipole moment substantially perpendicular to the longitudinal axis and the dipole moment of the second coil antenna.

6. The logging tool of claim 1, wherein one or more of the co-located antennas is a toroid antenna.

7. The logging tool of claim 1, wherein the co-located antennas comprise a combination of at least two of the group consisting of a toroid antenna, a tilted antenna, an axial antenna, and a transverse antenna.

8. The logging tool of claim 1, wherein the shield is made of non-magnetic metal.

9. The logging tool of claim 1, wherein each of the slots is filled with a non-conductive material.

10. A method to log a wellbore, comprising:

providing a downhole while-drilling logging tool comprising a tubular having a longitudinal axis, a set of co-located antennas carried in a recess on the tubular, a shield having an open slot configuration and circumferentially surrounding the set of co-located antennas, a first end of the shield being mechanically and electrically connected to the tubular, and an insulating ring carried on the tubular, at least a portion of the insulating ring being disposed between the tubular and a second end of the shield; and

making measurements with the logging tool while drilling the wellbore.

11. The method of claim 10, further comprising determining formation properties and/or other downhole parameters from the measurements.

12. The method of claim 11, wherein the formation properties and other downhole parameters include resistive anisotropy, relative dip, azimuth, and distances to bed boundaries.

13. The method of claim 11, further comprising making drilling decisions based on the determined formation properties and/or other downhole parameters.

14. A resistivity sensor disposed in a recess in a tubular having a longitudinal axis and adapted for subsurface disposal, comprising:

an insulating base layer disposed in the recess;

a set of co-located antennas disposed over the insulating base layer;

a shield having an open slot configuration, disposed over the recess, having a first end and a second end, the first end being attached to the tubular; and

an insulating ring attached to the tubular and forming a circumferential gap between the insulating ring and the second end of the shield.

15. The resistivity sensor of claim 14, wherein the circumferential gap is filled with an insulating material.

16. The resistivity sensor of claim 14, wherein the set of co-located antennas comprise a combination of at least two of the group consisting of a toroid antenna, a tilted antenna, an axial antenna, and a transverse antenna.

17. The resistivity sensor of claim 14, wherein the shield is made of non-magnetic metal.

18. The resistivity sensor of claim 14, wherein each of the slots is filled with a non-conductive material.

19. The resistivity sensor of claim 14, wherein one or more of the co-located antennas is tilted relative to the longitudinal axis or one or more of the co-located antennas is a toroid antenna.

20. The resistivity sensor of claim 14, wherein the set of co-located antennas comprises a first coil antenna having a dipole moment substantially parallel to the longitudinal axis, a second coil antenna having a dipole moment substantially perpendicular to the longitudinal axis, and a third coil antenna having a dipole moment substantially perpendicular to the longitudinal axis and the dipole moment of the second coil antenna.