Selectable Tap Induction Coils for Electromagnetic Well Logging
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Solution Overview
Problem
Conventional induction array tools in electromagnetic well logging face challenges in achieving high sensitivity due to significant direct coupling between transmitter and receiver coils, which is several orders of magnitude stronger than true signals, requiring precise balancing that is difficult to achieve and maintain, especially in short arrays where variations in temperature and pressure lead to errors.
Innovation Solution
The use of Selectable Tap Induction Coils (STIC) allows for selective connection of multiple windings to the transmitter or receiver coils, enabling adjustment of the effective magnetic moment to balance the array without moving parts, by measuring mutual coupling and interconnecting coils to minimize unwanted direct coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional induction array tools use fixed transmitter and receiver coils, then the tool structure is simple, but direct coupling between coils is several orders of magnitude stronger than true signals, making balancing difficult to achieve and maintain
Solution Approach 1:
The patent implements dynamic coil configuration by providing multiple selectable windings (first, second, third windings) with different numbers of turns that can be selectively connected to the transmitter or receiver. This dynamic reconfiguration allows the system to adapt the coil configuration to minimize direct coupling and optimize the signal-to-noise ratio under varying downhole conditions, thereby improving measurement precision while managing device complexity through structured selection mechanisms.
Solution Approach 2:
The patent changes the effective parameters of the induction coils by providing windings with different numbers of turns (e.g., 100 turns, 200 turns, 300 turns) that can be selectively connected. By changing the number of turns parameter, the system can adjust the magnetic moment and coupling characteristics to achieve optimal balancing between direct coupling and true signals, improving measurement precision without requiring complete redesign of the coil structure.
2Measurement precision
If the array is balanced to reduce direct coupling, then measurement precision improves, but variations in temperature and pressure cause balancing errors, especially in short arrays
Solution Approach 1:
The patent employs dynamic reconfiguration of coil connections in response to varying downhole conditions. By selectively connecting different windings based on measured mutual coupling and environmental conditions, the system can dynamically maintain optimal balancing despite temperature and pressure variations, thereby improving both measurement precision and reliability under changing conditions.
Solution Approach 2:
The patent implements a feedback mechanism where mutual coupling between transmitter and receiver is measured, and based on this measurement, the system selectively connects appropriate windings to achieve optimal balancing. This closed-loop feedback approach allows the system to automatically compensate for balancing errors caused by temperature and pressure variations, improving both precision and reliability.
3Object-affected harmful factors
If multiple coils are used for balancing, then direct coupling is reduced, but the device complexity and manufacturing costs increase
Solution Approach 1:
The patent segments the coil system into multiple independent windings (first, second, third windings) with different numbers of turns, where each winding can be selectively connected to the transmitter or receiver. This segmentation allows the system to reduce direct coupling by choosing the appropriate winding configuration while keeping the overall device complexity manageable through structured connection mechanisms and selection logic.
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 allows for precise balancing of induction arrays, reducing errors and maintaining sensitivity across varying conditions, reducing manufacturing complexity and costs, and enabling use in various well logging tools like wireline, LWD, and MWD.
Implementation Method 1
A typical logging tool includes a 'sonde', that emits, for example, acoustic or EM waves to interact with the surrounding formation. The signals produced from such interactions are then detected and measured by one or more sensors on the instrument.
Implementation Method 2
The use of Selectable Tap Induction Coils (STIC) allows for selective connection of multiple windings to the transmitter or receiver coils, enabling adjustment of the effective magnetic moment to balance the array without moving parts, by measuring mutual coupling and interconnecting coils to minimize unwanted direct coupling.
Data Source
AI summary
An electromagnetic logging tool includes a support configured for disposal in a well; at least one antenna mounted on the support; and a plurality of coils mounted on the support proximate the at least one antenna, wherein the plurality of the coils are configured for selective connection with the at least one antenna. A method for balancing an induction array on an electromagnetic logging tool includes measuring a mutual coupling between a transmitter and a receiver on the electromagnetic logging tool; and selectively connecting a subset of a plurality of coils on the electromagnetic logging tool to the transmitter or the receiver based on the measured mutual coupling.