Cross-slot Bobbin Antenna Shield for Co-located Antennas

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Solution Overview

Problem

Wellbore logging tools with co-located loop antennas face significant electromagnetic field leakage due to mechanical impacts, leading to reduced sensitivity and efficiency in resistivity measurements.

Innovation Solution

The use of a cross-slot bobbin arrangement with co-located loop antennas and antenna shields featuring longitudinal slots minimizes electromagnetic field leakage by isolating the antennas from each other, maintaining optimal electromagnetic field angles and reducing cross-talk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If antenna shields are used to protect loop antennas from mechanical impacts, then reliability is improved, but electromagnetic field leakage occurs reducing measurement precision

Engineering Contradiction:

Improveprotection from mechanical impactsVSAvoidelectromagnetic field leakage

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The antenna shield is segmented with longitudinal slots that allow electromagnetic fields to pass through while maintaining mechanical protection. The shield is divided into multiple sections (slots) rather than being a continuous structure, enabling selective transmission of electromagnetic signals while retaining protective function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The antenna shield has different properties in different locations: solid material provides mechanical protection, while longitudinal slots provide electromagnetic field transmission pathways. This local differentiation of properties allows the single structure to fulfill both protective and electromagnetic transmission functions.

Inventive Principle:

Principle #3Local quality

2Device complexity

If co-located loop antennas are positioned close together to save space, then device complexity is reduced, but cross-talk between antennas increases

Engineering Contradiction:

Improveantenna arrangementVSAvoidcross-talk between antennas

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The electromagnetic fields of each antenna are extracted and guided through dedicated longitudinal slots in the antenna shield. By providing separate transmission pathways for each antenna's electromagnetic field, cross-talk is minimized even though the antennas are co-located in the same space.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The antenna shield with longitudinal slots acts as an intermediary structure between the co-located antennas and the surrounding environment. It mediates the electromagnetic fields by providing controlled transmission pathways, preventing direct interference between adjacent antennas while maintaining their close proximity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If longitudinal slots are added to antenna shields to reduce electromagnetic field leakage, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveelectromagnetic field transmissionVSAvoidshield structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The antenna shield with longitudinal slots performs multiple functions simultaneously: mechanical protection of antennas, electromagnetic field transmission through slots, and isolation of co-located antennas to prevent cross-talk. This multi-functionality reduces the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The protective function and electromagnetic transmission function are merged into a single antenna shield structure. Rather than using separate protective covers and transmission windows, the shield itself is designed with longitudinal slots that combine both functions in one component.

Inventive Principle:

Principle #5Merging (Combining)

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 sensitivity and efficiency of resistivity logging tools by minimizing electromagnetic field leakage and maintaining effective electromagnetic field angles, thereby improving measurement accuracy.

Implementation Method 1

the antenna shield can include a plurality of longitudinal slots for permitting electromagnetic fields to penetrate the antenna shield to be transmitted or received

Methodology Applied

Scientific EffectElectromagnetic field penetration: Electromagnetic Induction

Data Source

PatentUS11169297B2Cross-slot bobbin and antenna shield for co-located antennas

Publication Date: 2021.11.09 HALLIBURTON ENERGY SERVICES INC

AI summary

A logging tool includes a mandrel having an axis, a bobbin positioned about the circumference of the mandrel, and defining a first cross slot at a first slot angle and a second cross slot at a second slot angle opposite the first slot angle. The first and second cross slots intersect each other. The tool includes a first antenna in the first slot and including a first plurality of windings wrapped about the mandrel, a second antenna co-located with the first antenna and in the second slot, and an antenna shield secured to the tool mandrel and in each of the first and second slots. The first antenna is arranged in a first orientation and at a first winding angle. The second antenna is arranged in a second orientation and at a second winding angle.