Rotating Coil Antenna for Electromagnetic Ranging Interference
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Solution Overview
Problem
Existing methods for determining the relative position and direction of a conductive pipe, such as in drilling applications, face interference issues due to direct electromagnetic signals between the transmitter and receiver, which reduces accuracy in ranging operations.
Innovation Solution
The use of a rotating coil antenna system with orthogonal transmitter and receiver configurations, where the receiver is made insensitive to the direct EM signal, allowing for accurate determination of distance and direction by analyzing the magnetic field induced in the target pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current is induced on a target casing by transmitting electromagnetic waves via coil antennas, then the amplitude of the secondary field can be used to determine the distance to the target casing, but the transmitted EM signal may interfere with the reception of the secondary EM signal
Solution Approach 1:
The patent applies dynamics by rotating the coil antenna in a horizontal plane during the electromagnetic signal transmission. This dynamic rotation causes the transmitted EM signal to vary in orientation relative to the receiver, allowing the system to distinguish between the direct transmitted signal and the secondary field signal from the target casing. The rotation transforms the static interference problem into a dynamic signal separation problem that can be resolved through temporal or angular analysis.
Solution Approach 2:
The patent employs periodic action by using a rotating coil antenna that transmits electromagnetic signals at multiple azimuth angles in a periodic manner. The receiver captures signals at different orientations, and the system uses this periodic variation to separate the direct transmitted signal from the secondary field signal. The periodic rotation creates a time-varying or angle-varying signal pattern that enables interference rejection while maintaining distance measurement capability.
2Adaptability or versatility
If coil antennas are used to transmit electromagnetic waves for ranging, then the system can determine relative position and direction, but direct electromagnetic interference between transmitter and receiver reduces ranging accuracy
Solution Approach 1:
The patent makes the coil antenna dynamic by rotating it in a horizontal plane during signal transmission. This rotation creates time-varying or angle-varying signal patterns that allow the receiver to distinguish between direct transmitted signals and secondary fields from target casings. The dynamic orientation changes enable the system to maintain ranging capability while rejecting direct EM interference, thereby improving accuracy.
Solution Approach 2:
The patent implements feedback by having the receiver capture electromagnetic signals at multiple azimuth angles through the rotating coil, and then using this feedback information to separate the direct transmitted signal from the secondary field signal. The system analyzes the signal patterns obtained at different orientations and uses this feedback to calculate accurate distance measurements, effectively compensating for the interference present in the raw signals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of ranging operations by eliminating interference from direct EM signals, enabling precise location and direction determination of conductive targets, such as in well intersection or parallel drilling scenarios.
Implementation Method 1
transmitting a first electromagnetic signal from a transmitter coil in a tool; receiving a second electromagnetic signal with a receiver coil in the tool
Implementation Method 2
receiving a second electromagnetic signal with a receiver coil in the tool, wherein at least one of the transmitting coil or the receiver coil is rotating
Implementation Method 3
The amplitude of this secondary field can be used to determine the distance to the target casing
Data Source
AI summary
A rotating coil antenna tool apparatus includes a transmitter coil and a receiver coil that are used for ranging to a target well. The transmitter coil transmits a first electromagnetic signal and the receiver coil receives second electromagnetic signal. At least one of the transmitting coil or the receiver coil is rotating while transmitting or receiving their respective signals. The receiver coil is inhibited from receiving the first electromagnetic signal. A relative distance and/or direction to the target well is determined based on the second electromagnetic signal.