Downhole Wireline Tool Voltage Peak Reduction
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Solution Overview
Problem
Existing wireline downhole tools face challenges in high-temperature wells due to the inability of frequency converters to withstand peak steady-state voltages, leading to potential damage and tool failure, which is costly and time-consuming to rectify.
Innovation Solution
A downhole wireline tool equipped with a high-temperature capacitor and a voltage peak reduction unit, comprising a resistor and transistor activated by a control unit, to reduce steady-state voltage peaks and protect the frequency converter from excessive voltages, allowing the tool to operate safely in high-temperature environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a frequency converter is used to power the electrical motor in the downhole tool, then the motor can operate with variable speed and torque control, but the frequency converter is vulnerable to damage from peak steady-state voltages in high-temperature environments
Solution Approach 1:
A voltage peak reduction unit is introduced as an intermediary component between the power supply and the frequency converter. This unit includes a capacitor that detects peak steady-state voltages and activates a crowbar circuit (transistor and resistor) to clamp the voltage when it exceeds a predetermined threshold, thereby protecting the frequency converter from voltage-induced damage while allowing the motor to maintain variable speed control capability
Solution Approach 2:
The capacitor in the voltage peak reduction unit is pre-configured with specific capacitance values (80-150 μF) to anticipate and counteract voltage peaks before they can damage the frequency converter. The crowbar circuit is pre-arranged to activate automatically when voltage thresholds are exceeded, providing beforehand protection against potential damage in high-temperature downhole environments
2Reliability
If a high-temperature capacitor is used to reduce voltage peaks, then the frequency converter is protected from voltage damage, but the capacitor requires larger size and energy storage capacity to effectively withstand high temperatures above 150°C
Solution Approach 1:
The patent specifies precise capacitance parameter ranges (80-150 μF) for the high-temperature capacitor to optimize its performance. By carefully selecting capacitance values within this range, the design achieves effective voltage peak reduction and frequency converter protection while minimizing the capacitor's physical size and energy storage requirements, making it suitable for compact downhole tool applications
Solution Approach 2:
The capacitor employs a high-temperature dielectric material capable of withstanding temperatures above 150°C. This specialized material composition allows the capacitor to maintain its electrical properties and protective function in high-temperature downhole environments without requiring excessive size or energy storage capacity
3Ease of operation
If wireline tools are used in high-temperature wells, then operations can be performed with precise electrical control, but the tools face extreme thermal challenges that coiled tubing equipment avoids
Solution Approach 1:
The patent replaces purely mechanical thermal protection approaches with an electrical control system that includes a frequency converter and voltage peak reduction unit. The capacitor-based voltage clamping mechanism provides precise electrical control of the motor while simultaneously protecting against thermal-related voltage peaks, enabling wireline tools to operate in high-temperature wells with both precision and thermal resilience
Solution Approach 2:
The frequency converter enables dynamic adjustment of motor operating parameters (speed, torque) to adapt to high-temperature conditions. By controlling the motor's electrical parameters, the system optimizes performance and reduces thermal stress on components, allowing precise electrical control to coexist with high-temperature operation capability
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 enables the tool to operate effectively in high-temperature wells by preventing voltage-induced damage to the frequency converter, reducing the size and energy storage capacity requirements of the high-temperature capacitor, and ensuring reliable operation without the need for frequent tool withdrawal.
Implementation Method 1
the voltage peak reduction unit comprises a capacitor, wherein the capacitor is a high temperature capacitor having a dielectric comprising a material capable of resisting a temperature above 150°C
Implementation Method 2
a high temperature capacitor having a dielectric comprising a material capable of resisting a temperature above 150°C
Implementation Method 3
the control unit activates the transistor which then allows excessive power to be dissipated in the resistor
Data Source
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AI summary
The present invention relates to a downhole wireline tool for performing an operation in a well at a depth of up to 15 km downhole, the tool being powered by direct current at a predetermined voltage in a first end by a power supply unit which is configured to provide a specific steady-state voltage selected from a plurality of predetermined voltages, comprising an electrical motor being powered by alternating current, a frequency converter arranged between the first end and the motor, and a voltage peak reduction unit adapted to reduce the steady-state voltage of the selected power supplied to the frequency converter from the power supply, the voltage peak reduction unit comprising a capacitor, wherein the capacitor is a high temperature capacitor having a dielectric comprising a material capable of resisting a temperature above 150°C. Furthermore, the present invention relates to a downhole tool string and to a method of protecting a frequency converter from peaks of voltage in power supplied to the frequency converter in a downhole tool according to the present invention.