Tilted Coil Antenna Assembly for Wellbore Logging
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Solution Overview
Problem
Existing wellbore logging tools face challenges in achieving high azimuthal sensitivity and efficient electromagnetic signal transmission due to interference from drill collars, which affects the accuracy of resistivity measurements in subterranean formations during drilling operations.
Innovation Solution
The use of a tilted coil antenna assembly with a bobbin made of high-temperature materials, featuring channels for wrapping coil windings at an offset angle, enhances magnetic field directionality and reduces interference, allowing for improved azimuthal sensitivity and signal shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coil windings are positioned about an axial section of the wellbore logging tool with ferrite material, then magnetic field directionality and signal shielding are improved, but interference from drill collars still affects measurement accuracy
Solution Approach 1:
The patent applies asymmetry by positioning the coil windings at an offset angle (e.g., 45 degrees) relative to the axial section of the wellbore logging tool, rather than symmetrically around the axis. This asymmetric configuration creates a tilted coil antenna assembly that generates a magnetic field with specific directional characteristics, allowing the antenna to be more sensitive to formations in certain azimuthal directions while being less affected by drill collar interference in other directions.
Solution Approach 2:
The patent uses ferrite material as an intermediary substance positioned beneath the coil windings. The ferrite provides a high magnetic permeability path that concentrates and directs the magnetic field generated by the coil windings, while also shielding the coil from eddy currents induced in the conductive drill collar. This intermediary ferrite layer acts as a magnetic flux conduit that improves signal strength and reduces harmful electromagnetic interference from the drill collar.
2Use of energy by moving object
If ferrite material is positioned beneath coil windings to increase efficiency, then magnetic permeability and signal shielding are improved, but signal loss and sensitivity issues persist
Solution Approach 1:
The patent employs composite materials by combining ferrite (a ferromagnetic material with high magnetic permeability) with the coil winding structure and the tilted bobbin assembly. This composite configuration creates a system where the ferrite enhances magnetic field generation and directionality, while the tilted geometry optimizes the interaction between the magnetic field and the surrounding formations, thereby improving overall signal transmission efficiency and reducing losses.
Solution Approach 2:
The patent changes the geometric parameter of the coil antenna by tilting it at a specific angle (e.g., 45 degrees) relative to the axial section. This parameter change optimizes the magnetic field orientation to maximize sensitivity to formation resistivity variations while minimizing coupling with the drill collar. The angular parameter optimization, combined with ferrite material properties, reduces signal loss and improves transmission efficiency.
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 configuration enhances the accuracy of resistivity measurements by minimizing signal loss and maximizing sensitivity, enabling more precise characterization of subterranean formations.
Implementation Method 1
The ferrites facilitate a higher magnetic permeability path (i.e., a flux conduit) for the magnetic field generated by the coil windings
Implementation Method 2
help shield the coil windings from the drill collar and associated losses (e.g., eddy currents generated on the drill collar)
Implementation Method 3
The use of a tilted coil antenna assembly with a bobbin made of high-temperature materials, featuring channels for wrapping coil windings at an offset angle, enhances magnetic field directionality and reduces interference
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A single layer antenna path profile is provided. An antenna assembly for the single layer antenna profile includes a bobbin having a cylindrical body defining an outer radial surface, an inner radial surface, and a central axis. The antenna assembly also includes one or more channels defined in the outer radial surface. In some aspects, each channel is defined by a continuously curved inner surface having a constant radius. In some aspects, the inner surface extends more than 180 but less than 360 and thereby defines an opening in the body. The antenna assembly also includes a coil including a wire wrapped about the bobbin and received within the one or more channels. In some aspects, an arcuate portion of the wire extends through the opening such that a portion of the wire protrudes out of the channel.