Electrochemical Scratch Tool for Sour Field Repassivation Kinetics
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Solution Overview
Problem
Current studies on repassivation kinetics of steels do not accurately simulate sour field conditions prevalent in oil and gas pipelines, lacking the presence of hydrogen sulfide and proper simulation of corrosion damage, which hinders effective testing of repassivation kinetics and corrosion inhibitor effectiveness.
Innovation Solution
An electrochemical system and method that simulate sour oil field conditions by using a housing made of metallic material with an electrolyte and a scratch tool to create controlled scratches on a sample, allowing for the measurement of repassivation kinetics and corrosion inhibitor film persistency, with features including a gas inlet to simulate sour conditions and electrical power to generate an electrochemical cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional repassivation studies are conducted without simulating sour field conditions, then the testing process is simpler and does not require complex equipment, but the results do not accurately reflect real-world corrosion behavior in oil and gas pipelines
Solution Approach 1:
The system divides the testing environment into separate functional components: an electrochemical cell for controlling the chemical environment, a scratch tool for creating controlled damage, and a purging system for introducing H2S. This segmentation allows each component to be optimized independently while achieving accurate sour condition simulation.
Solution Approach 2:
The patent introduces an electrolyte solution as an intermediary medium that facilitates the electrochemical reactions and enables the simulation of sour field conditions. The electrolyte acts as a bridge between the metallic sample, the scratch tool, and the H2S atmosphere, allowing accurate measurement of repassivation kinetics without requiring the entire system to be complex.
2Reliability
If the passive film is allowed to accumulate damage over time without intervention, then the natural corrosion process is preserved, but rapid crack formation and pipe failure may occur
Solution Approach 1:
The system performs preliminary scratching of the passive film to create controlled damage before measuring repassivation kinetics. By proactively creating the damage condition rather than waiting for natural corrosion progression, the system can immediately measure the repassivation response and evaluate corrosion resistance without allowing uncontrolled damage accumulation that would lead to pipe failure.
Solution Approach 2:
The electrochemical measurement system provides real-time feedback on the repassivation process by monitoring current changes as the passive film reforms after scratching. This feedback mechanism allows the system to quantify corrosion resistance and evaluate how quickly the material can heal itself, enabling assessment of reliability before critical damage occurs.
3Adaptability or versatility
If existing repassivation studies are used without simulating proper area ratio of damaged film to steel structure, then the testing is easier to conduct, but the results cannot be properly applied to actual pipeline conditions
Solution Approach 1:
The system allows adjustment of the scratch area size and depth parameters to simulate different damage scenarios while maintaining the proper area ratio between damaged film and steel structure that exists in actual pipelines. By making these parameters可调 (adjustable), the system can adapt to various field conditions while using a relatively simple electrochemical cell setup.
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
Enables accurate measurement of repassivation kinetics and corrosion inhibitor film persistency under simulated sour oil field conditions, effectively quantifying the corrosion resistance and inhibitor performance by creating a controlled environment that mimics field conditions, thereby improving the understanding and prevention of corrosion in oil and gas infrastructure.
Implementation Method 1
an electrical power source coupled to the housing and the sample within the scratch tool so as to generate an electric current between the housing and the sample, wherein the sample holder is movable with respect to the pin tip to create a scratch on the sample within the electrolyte
Implementation Method 2
at least one of the insulating covers includes a gas inlet port and a gas outlet port, the gas inlet port providing an inlet for purge gas to be bubbled through the electrolyte to simulate the sour filed conditions
Implementation Method 3
a pin tip positioned with respect to the sample to scratch off a passivation film from the sample surface
Implementation Method 4
Steel is known to react and oxidize readily when exposed to water, oxygen, and/or acid gases resulting in the production of a 'passive' oxidized film on the surfaces of steel structures
Data Source
AI summary
An electrochemical system for measuring the repassivation kinetics of a metallic material under sour oil field conditions comprises a housing made of the metallic material surrounding an internal space; insulating covers positioned on the housing, an electrolyte enclosed within the internal space of the housing and the insulating covers, a scratch tool including a second housing made of an insulting material that one end positioned in the electrolyte, a sample holder for holding a sample composed of the metallic material, and a pin tip positioned to scratch off a passivation film from the sample surface, and an electrical power source coupled to the housing and the sample within the scratch tool so as to generate an electric current between the housing and the sample, wherein the sample holder is movable with respect to the pin tip to create a scratch on the sample within the electrolyte.