Flexible Circuit for Downhole Antenna

• US 20080030415A1
• Filed: 08/02/2006
• Published: 02/07/2008
• Est. Priority Date: 08/02/2006
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Frey, Mark T., Homan, Dean M.
• Granted Patent: US 7,916,092 B2
• Time in Patent Office: Days
• US Class Current: 343/719
• CPC Class Codes: H01Q 1/04 Adaptation for subterranean or subaqueous use
• CPC Class Codes: H01Q 1/20 Resilient mountings
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An antenna for an electromagnetic tool having a longitudinal axis and a core. The antenna includes a flexible dielectric substrate flexibly conformed about the core and an electrical conductor disposed on the dielectric substrate. The electrical conductor is disposed on the substrate such that the antenna has a dipole moment having any desired direction relative to the longitudinal axis of the tool.

Claims

1. An antenna for an electromagnetic tool used in a wellbore, the tool having a core with a longitudinal axis, the antenna comprising:

a flexible dielectric substrate conformed about the core; and

a set of electrical conductor segments disposed on the substrate, the electrical conductor segments having first ends and second ends such that the first ends are electrically joined to the second ends to form a multiturn coil.

2. The antenna of claim 1, wherein the substrate is, contains, or has disposed upon it a flexible magnetic material.

3. The antenna of claim 1, wherein the electrical conductor segments are disposed in multiple layers to form a multilayered, multiturn coil.

4. The antenna of claim 1, wherein the electrical conductor segments extend in a generally sinusoidal pattern on the dielectric substrate.

5. The antenna of claim 1, wherein the coil is tilted relative to the longitudinal axis.

6-13. -13. (canceled)

14. An antenna for an electromagnetic tool used in a wellbore, the tool having a longitudinal axis and a core, the antenna comprising:

a flexible dielectric substrate conformed about the core; and

a first set of electrical conductor segments and a second set of electrical conductor segments electrically separated and disposed on the substrate, the electrical conductor segments having upper ends and lower ends such that the upper ends of the first and second sets are electrically joined and the lower ends of the first and second sets are electrically joined to form a toroid.

15. The antenna of claim 14, wherein the substrate is, contains, or has disposed upon it a flexible magnetic material that resides in an interior region of the toroid.

16. The antenna of claim 14, wherein the antenna further comprises multiple first and second sets of electrical conductor segments disposed in substantially parallel arrangement to form a toroid having an enhanced number of turns.

17. The antenna of claim 16, wherein the multiple first and second sets are electrically connected to form a transformer.

18. The antenna of claim 14, wherein the toroid is of sufficient length to wrap around the core multiple times, thereby forming a super toroid.

19. The antenna of claim 14, wherein the toroid extends in a generally sinusoidal pattern on the dielectric substrate when the dielectric substrate is flat.

20. The antenna of claim 14, wherein the toroid has a central plane and the central plane of the toroid is tilted, transverse, or parallel relative to the longitudinal axis.

21. The antenna of claim 14, wherein the dielectric substrate is an annular ring.

22. The antenna of claim 21, further comprising multiple toroids on multiple annular rings stacked to form a super toroid.

23. An electromagnetic tool used in a wellbore and having a longitudinal axis, the tool comprising:

one or more cores on the tool;

one or more antennas carried on the one or more cores, each of the one or more antennas comprising;

a flexible dielectric substrate conformed about the core; and

sets of electrical conductor segments disposed on the substrate, each set of electrical conductor segments having upper ends electrically joined and lower ends electrically joined to form a toroid having an electric dipole moment.

24. The tool of claim 23, wherein the substrate is, contains, or has disposed upon it a flexible magnetic material that resides within an interior region of the toroid.

25. The tool of claim 23, wherein the toroid extends in a generally sinusoidal pattern on the dielectric substrate when the dielectric substrate is flat.

26. The tool of claim 23, wherein the toroid has a central plane and the central plane of the toroid is tilted, transverse, or parallel relative to the longitudinal axis.

27. The tool of claim 23, wherein the electric dipole moments of the toroids are orthogonal.

28. The tool of claim 23, wherein the electric dipole moments of the toroids are orthogonal and at least one toroid is tilted relative to the longitudinal axis.

29. The tool of claim 23, wherein the electric dipole moments have different azimuthal orientations relative to each other.

30. The tool of claim 23, wherein the one or more antennas carried on one of the one or more cores are co-located.

31. The tool of claim 23, wherein at least one of the one or more cores is a face of a pad on a resistivity tool.

32. A method to obtain information on the electromagnetic properties of a subsurface formation using an electromagnetic tool having a longitudinal axis and one or more cores, the method comprising:

conforming a flexible circuit board about each of the one or more cores to form a toroid therearound, the flexible circuit board having a first set of electrical conductor segments and a second set of electrical conductor segments electrically separated and disposed on a substrate, the electrical conductor segments having upper ends and lower ends such that the upper ends of the first and second sets are electrically joined and the lower ends of the first and second sets are electrically joined;

broadcasting an electromagnetic signal from at least one of the toroids into the formation; and

receiving at least a portion of the signal returned from the formation.

33. A method to construct an antenna used to obtain information on the electromagnetic properties of a subsurface formation, the method comprising:

providing a flexible dielectric substrate;

securing electrical conductor segments having upper and lower ends onto the substrate to form a flexible circuit board;

conforming the flexible circuit board about a core of an electromagnetic measurement tool; and

electrically joining the upper ends and electrically joining the lower ends of the electrical conductor segments to form one or more toroids about the core.