Receiver System For Determining The Location Of A Magnetic Field Source
First Claim
1. A method for guiding a downhole tool assembly, the method comprising:
- setting a receiver assembly at a target point, the receiver assembly comprising two antenna assemblies disposed in a substantially horizontal plane, such that the two antenna assemblies each lie on a desired borepath; and
simultaneously detecting in three dimensions at each of the two antenna assemblies a magnetic field transmitted from the downhole tool assembly to determine a position of the downhole tool assembly.
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Accused Products
Abstract
A method and receiver system for identifying a location of a magnetic field source using two horizontally displaced tri-axial antennas. In a preferred embodiment two tri-axial antennas are positioned at opposite ends of a receiver frame. Each antenna detects in three dimensions a magnetic field from a source or transmitter. The receiver is maintained in a horizontal plane and the receiver is moved in the horizontal plane until a flux angle measured at each of the two points is zero so that the receiver is in the vertical plane perpendicular to the axis of the source. The depth and location of the source in three dimensions relative to the receiver is determined using the detected field values. The receiver is moved in a direction defined by a line containing the two points of the receiver until a magnitude of the magnetic field detected at each of the two points is substantially the same so that the receiver is positioned above the source.
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Citations
23 Claims
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1. A method for guiding a downhole tool assembly, the method comprising:
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setting a receiver assembly at a target point, the receiver assembly comprising two antenna assemblies disposed in a substantially horizontal plane, such that the two antenna assemblies each lie on a desired borepath; and simultaneously detecting in three dimensions at each of the two antenna assemblies a magnetic field transmitted from the downhole tool assembly to determine a position of the downhole tool assembly. - View Dependent Claims (2, 3, 4, 5, 7, 8)
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6. The method of claim I further comprising the step of using the fields detected by the two antenna assemblies to determine whether the downhole tool assembly is approaching or has passed the target point.
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9. A method for tracking a downhole tool assembly having a transmitter to transmit a magnetic field, the method comprising:
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maintaining two and only two tri-axial antennas of a receiver assembly in a substantially horizontal plane; simultaneously detecting in three dimensions the magnetic field at each of the two and only two tri-axial antennas; and moving the receiver assembly in a horizontal plane until a flux angle measured at each of the two antennas is zero. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A receiver assembly for tracking movement of a downhole tool assembly through the ground, the downhole tool assembly comprising a transmitter, the receiver assembly comprising:
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a frame; two and only two tri-axial antennas supported by the frame, wherein the two antennas detect a magnetic field from the transmitter; and a processor to receive an antenna signal from each of the two antennas and determine a location of the downhole tool assembly relative to the frame using the antenna signals; wherein the two antennas detect the magnetic field when the antennas are held in a substantially horizontal plane. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification