Tilted Coil Antennas With Stacked Soft Magnetic Inserts
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Solution Overview
Problem
Existing wellbore logging tools face challenges in achieving high gain, sensitivity, and efficiency in resistivity logging due to complex and costly soft magnetic band designs, which affect the accuracy of subterranean formation measurements.
Innovation Solution
The design incorporates tilted coil antennas with a soft magnetic band featuring stacked inserts made of commercially available rods, and an antenna shield with slots of varying lengths to enhance sensitivity and mechanical integrity, reducing manufacturing costs and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex soft magnetic band designs are used to improve gain and sensitivity, then measurement accuracy is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The soft magnetic band is divided into multiple discrete inserts positioned at specific locations around the coil, rather than using a continuous complex geometry. Each insert provides localized magnetic flux concentration, achieving the required measurement accuracy while simplifying manufacturing.
Solution Approach 2:
The patent uses commercially available rod materials for the soft magnetic inserts, replacing expensive custom-formed magnetic materials. This substitution with standard, easily manufactured components reduces both material cost and manufacturing complexity while maintaining functional performance.
2Ease of manufacture
If commercially available rods are used for stacked inserts, then manufacturing cost is reduced, but magnetic performance may be compromised
Solution Approach 1:
The patent optimizes parameters such as insert dimensions, spacing, and positioning to maximize the magnetic performance of commercially available rods. By carefully selecting and positioning these standard components, the design achieves magnetic flux concentration equivalent to or better than custom-designed solutions.
Solution Approach 2:
The soft magnetic inserts are positioned at specific locations where magnetic flux concentration is most beneficial for the tilted coil antenna operation. This localized approach ensures that the commercially available rods are placed where they provide maximum magnetic performance enhancement.
3Measurement precision
If antenna shield with slots is added to improve sensitivity, then gain and sensitivity are enhanced, but device complexity and manufacturing cost increase
Solution Approach 1:
The antenna shield is designed with discrete slots rather than continuous complex geometries. These slots are positioned to allow electromagnetic field transmission while blocking unwanted signals, achieving sensitivity enhancement through a simplified segmented structure that is easier to manufacture.
Solution Approach 2:
The slotted antenna shield acts as an intermediary component between the tilted coil antenna and the external environment. It selectively transmits desired electromagnetic signals while blocking interfering signals and eddy currents, enhancing sensitivity without requiring complex active control systems.
4Measurement precision
If tilted coil antenna design is used to improve directional sensitivity, then measurement accuracy is enhanced, but mechanical complexity increases
Solution Approach 1:
The coil is wound at a specific tilt angle relative to the drill string axis, creating an asymmetric configuration that provides directional sensitivity. This asymmetric tilt allows the antenna to differentiate between different formation directions, enhancing measurement accuracy while maintaining a relatively simple winding structure.
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
The solution enhances the gain and sensitivity of the antenna assemblies while maintaining mechanical strength and reducing costs, achieving comparable or better performance than traditional designs with complex geometries.
Implementation Method 1
The soft magnetic material facilitates a higher magnetic permeability path (i.e., a flux conduit) for the magnetic field generated by the coil windings
Implementation Method 2
helps shield the coil windings from adjacent drill collars and associated losses (e.g., eddy currents generated on the drill collars)
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
An antenna assembly includes a tool mandrel having a tool axis, and a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis. A soft magnetic band radially interposes the coil and the tool mandrel and extends about a circumference of the tool mandrel at a band angle parallel to the winding angle. The soft magnetic band includes a plurality of stacked inserts extending perpendicular to the coil about the circumference of the tool mandrel and each stacked insert includes a plurality of rods positioned end-to-end.