Coil winding methods for downhole logging tools
First Claim
1. A logging tool having an antenna for transmitting or receiving signals with a magnetic field component orthogonal to a longitudinal tool axis, the antenna including at least two portions arranged on opposite sides of the longitudinal tool axis, the antenna comprising:
- a conductive wire that forms at least four separate multi-loop windings in series between a first driving terminal that provides a positive voltage and a second driving terminal that provides a negative voltage equal in magnitude to the positive voltage, the at least four windings include at least two windings on each of the at least two portions, the conductive wire sustaining a voltage distribution along its length during operation of the antenna, the voltage distribution being symmetric about a grounded midpoint of the conductive wire, and the windings being arranged so that each winding on each portion of the antenna is matched by another winding on that portion having an equal and opposite voltage distribution.
2 Assignments
0 Petitions
Accused Products
Abstract
A logging tool and method for winding a multi-component induction (MCI) antenna is presented. The method eliminates unwanted dipole signals that are created by the voltage drop that takes place in the transmitter. The antenna is made of at least two parts physically separated, one on each side of the mandrel. The winding method is performed in a way that creates at least four windings arranged to eliminate dipole signals attributable to an asymmetric voltage distribution. The midpoint of the conductive wire that for is the antenna windings may be electrically attached to the tool body. This method is suitable for the winding of the cross-components X and Y of the MCI coil arrays.
21 Citations
20 Claims
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1. A logging tool having an antenna for transmitting or receiving signals with a magnetic field component orthogonal to a longitudinal tool axis, the antenna including at least two portions arranged on opposite sides of the longitudinal tool axis, the antenna comprising:
a conductive wire that forms at least four separate multi-loop windings in series between a first driving terminal that provides a positive voltage and a second driving terminal that provides a negative voltage equal in magnitude to the positive voltage, the at least four windings include at least two windings on each of the at least two portions, the conductive wire sustaining a voltage distribution along its length during operation of the antenna, the voltage distribution being symmetric about a grounded midpoint of the conductive wire, and the windings being arranged so that each winding on each portion of the antenna is matched by another winding on that portion having an equal and opposite voltage distribution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A multi-component array logging method comprising:
arranging a conductive wire to form an antenna with at least four separate multi-loop windings in series between a first driving terminal that provides a positive voltage and a second driving terminal that provides a negative voltage equal in magnitude to the positive voltage, the antenna transmitting or receiving signals with a magnetic field component orthogonal to a longitudinal tool axis, and the antenna having at least two portions arranged on opposite sides of the longitudinal tool axis, each portion having at least two of the at least four windings; and
attaching opposite ends of the conductive wire to first and second driving terminals; and
operating the antenna in a manner that creates a voltage distribution along the conductive wire'"'"'s length, the voltage distribution being symmetric about a grounded midpoint of the conductive wire so as to cause the voltage distribution along each winding on each portion of the antenna to be matched by a substantially equal and opposite voltage distribution on another winding on that portion.- View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
Specification