Subsurface electromagnetic measurements using cross-magnetic dipoles
First Claim
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1. A resistivity imaging tool for determining subsurface properties, comprising:
- an elongated body having a longitudinal axis and adapted for disposal within a subsurface borehole;
a transmitter disposed on the body and adapted to transmit electromagnetic energy; and
a receiver disposed on the body at a distance two inches (5 cm) or less from the transmitter and adapted to receive electromagnetic energy;
wherein the transmitter or receiver comprises at least one antenna with its axis tilted with respect to the longitudinal body axis, wherein each transmitter and receiver comprises two antennas with their axes substantially orthogonal to one another, the transmitter antennas and the receiver antennas being arranged in the same orthogonal directions; and
wherein the transmitter and receiver are both disposed in an insulating material within a cavity on the elongated body.
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Abstract
Sensor assemblies including transmitter and receiver antennas to respectively transmit or receive electromagnetic energy. The sensor assemblies are disposed in downhole tools adapted for subsurface disposal. The receiver is disposed at a distance less than six inches (15 cm) from the transmitter on the sensor body. The sensor transmitter or receiver includes an antenna with its axis tilted with respect to the axis of the downhole tool. A sensor includes a tri-axial system of antennas. Another sensor includes a cross-dipole antenna system.
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Citations
14 Claims
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1. A resistivity imaging tool for determining subsurface properties, comprising:
- an elongated body having a longitudinal axis and adapted for disposal within a subsurface borehole;
a transmitter disposed on the body and adapted to transmit electromagnetic energy; and
a receiver disposed on the body at a distance two inches (5 cm) or less from the transmitter and adapted to receive electromagnetic energy;
wherein the transmitter or receiver comprises at least one antenna with its axis tilted with respect to the longitudinal body axis, wherein each transmitter and receiver comprises two antennas with their axes substantially orthogonal to one another, the transmitter antennas and the receiver antennas being arranged in the same orthogonal directions; andwherein the transmitter and receiver are both disposed in an insulating material within a cavity on the elongated body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- an elongated body having a longitudinal axis and adapted for disposal within a subsurface borehole;
Specification