Electrochemical Sensor Insulating Coating for High Pressure Wellbores
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Solution Overview
Problem
Existing electrochemical sensors fail to provide stability and robustness in high temperature and high pressure wellbore conditions due to issues like electrolyte penetration and thermoelectric effects, leading to increased background response and metal stripping, rendering them ineffective for measuring corrosion-causing components like H2S and CO2.
Innovation Solution
A novel electrochemical sensor design featuring a bulkhead-like electrode assembly with a cylindrical housing, a seal ring, and a conductive pin coated with an insulating layer to prevent fluid or gas contact, ensuring stability and accuracy in high pressure and temperature environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If press-fitted electrodes are used in high pressure and high temperature conditions, then the sensor can be deployed in wellbore environments, but the electrolyte penetrates into the small gap between electrode materials and the main body, causing increased background response and metal stripping
Solution Approach 1:
The electrode assembly is divided into distinct functional segments: a first electrode structure with a first electrode and a second electrode structure with a second electrode, separated by an insulating barrier. This segmentation prevents electrolyte penetration between electrode materials and the main body, eliminating the background response and metal stripping issues while maintaining deployment capability in high pressure and high temperature wellbore environments.
Solution Approach 2:
An insulating barrier is introduced as an intermediary element between the first and second electrode structures. This barrier prevents direct contact between the electrolyte and the electrode materials, blocking the harmful electrolyte penetration pathway while allowing the sensor to function in high pressure and high temperature conditions.
2Ease of manufacture
If simple metal mounting procedures are used on top of electrical pin connectors, then the sensor manufacturing is simplified, but persistent creeping problems occur where liquid electrolyte penetrates into polymer sealant down to the electrical pin sections
Solution Approach 1:
The harmful electrolyte penetration pathway is extracted and eliminated by removing the small gap between electrode materials and the main body that previously allowed creeping. The insulating barrier is positioned to completely block the electrolyte from reaching the electrical pin sections, preventing the creeps problem while maintaining manufacturing simplicity.
Solution Approach 2:
The insulating barrier is designed as a simple, easily manufacturable component that provides effective protection against electrolyte penetration. This barrier can be integrated into the electrode assembly using standard manufacturing procedures, offering a cost-effective solution that prevents the persistent creeping problems without complicating the manufacturing process.
3Measurement precision
If the electrode is exposed to the high pressure region, then the sensor can measure corrosion-causing components accurately, but the conductive pin is vulnerable to direct contact with fluid or gas
Solution Approach 1:
The insulating barrier is applied locally to specific areas where electrolyte penetration occurs, providing targeted protection to the conductive pin while maintaining the electrode's exposure to the high pressure region for accurate measurement of corrosion-causing components. This localized approach prevents harmful contact without interfering with the measurement function.
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 design effectively prevents fluid penetration and maintains sensor integrity, reducing background noise and enhancing measurement accuracy for components such as hydrogen sulfide, carbon dioxide, and pH in hydrocarbon wellbore conditions.
Implementation Method 1
at least a part of the exterior surface of the conductive pin closer to the electrode is coated with an insulating coating which functions as a barrier to fluid or gas to protect the conductive pin from direct contact with the fluid or the gas
Implementation Method 2
a seal ring extending around the cylindrical housing of the electrode assembly to serve as a barrier between a high pressure region and a low pressure region
Data Source
AI summary
An electrochemical sensor for measuring contents of a fluid or gas at high pressure and/or high temperature, for use, for example, in a wellbore for hydrocarbon applications, is provided. The sensor includes: a bulkhead-like electrode assembly including a cylindrical housing and a cylindrical electrode structure. The cylindrical electrode structure includes a cylindrical conductive pin extending from a high pressure region to a low pressure region and an electrode connected to one end of the pin at the high pressure region and having an electrode surface for exposure to a flow path of the fluid or gas in the high pressure region. At least a part of the surface of the pin is protected from direct contact with the fluid or the gas by an insulating coating impermeable to the fluid or gas. The pin may include an alternating pattern of protruding and receded portions.