Sucker Rod Anodic Coating for Corrosion Inhibition
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Solution Overview
Problem
Current corrosion protection methods for sucker rod pumping systems in oil and gas wells are inadequate as they either fail to protect all downhole components, are costly, or lead to premature failure due to disbondment, abrasion, and incompatibility with elastomeric parts, especially in deeper, hotter, and more corrosive environments.
Innovation Solution
Implementing an anodic coating on sucker rod surfaces that acts as a sacrificial anode, electrically connected to other components, providing cathodic protection and self-healing properties to inhibit corrosion across the entire system, including sucker rods, tubing, and pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thermoplastic polymer coating is applied to sucker rods, then corrosion protection is provided, but the coating disbonds and strips off due to insufficient bonding strength
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of a primer layer with phosphating or chromating treatment, followed by a thermoplastic polymer coating layer. This composite structure provides both corrosion protection and adequate bonding strength, resolving the contradiction between protection and reliability.
Solution Approach 2:
The patent modifies the surface parameters of the sucker rod by applying phosphating or chromating treatments that create a crystalline surface layer with improved adhesion properties. This parameter change in surface chemistry enables the thermoplastic coating to bond effectively while maintaining corrosion resistance.
2Object-affected harmful factors
If fusion bonded epoxy coating is applied to sucker rods, then modest corrosion protection is achieved, but the coating is subject to abrasion and requires complicated application procedures
Solution Approach 1:
The patent employs a thermoplastic polymer coating that can be applied via spray methods and provides adequate service life. While not as durable as epoxy, the simplified application process and lower cost make it economically viable, trading some durability for ease of manufacture.
Solution Approach 2:
The patent changes the application parameters by using thermoplastic materials that can be applied at lower temperatures and with simpler equipment compared to fusion bonded epoxy. The coating is applied in a molten state and then cooled to form a protective layer, eliminating the need for complex pre-heating and curing procedures.
3Object-affected harmful factors
If metal alloys with higher corrosion resistance are used, then corrosion protection is improved, but production cost increases significantly
Solution Approach 1:
The patent uses a composite approach where conventional carbon steel sucker rods are coated with a protective thermoplastic polymer layer. This combines the cost advantage of carbon steel with the corrosion resistance of the polymer coating, achieving protection without the high cost of corrosion-resistant alloys.
Solution Approach 2:
The thermoplastic polymer coating acts as an intermediary barrier between the carbon steel sucker rod and the corrosive downhole environment. This intermediate layer provides corrosion protection to the inexpensive carbon steel substrate, avoiding the need for expensive alloy materials.
4Object-affected harmful factors
If chemical corrosion inhibitors are used, then some corrosion protection is achieved, but they are difficult to transport to downhole locations and incompatible with elastomeric parts
Solution Approach 1:
The patent replaces the chemical corrosion inhibition approach with a physical barrier approach using thermoplastic polymer coating. This mechanical/physical barrier eliminates the need for chemical inhibitors, avoiding their transport and compatibility issues while providing effective corrosion protection.
Solution Approach 2:
The thermoplastic polymer coating serves as a physical intermediary barrier between the corrosive chemicals and the sucker rod surface. This eliminates the need for chemical corrosion inhibitors that would need to be transported and injected, and avoids incompatibility issues with elastomeric pump components.
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 anodic coating effectively reduces corrosion across all components, maintains protection even after wear, and extends the lifespan of sucker rod pumping systems, reducing operational costs and avoiding issues like coating disbondment and fluid ingress.
Implementation Method 1
an anode including an anodic coating on a surface of a body of a sucker rod string... configured to at least partially inhibit corrosion of the cathode
Data Source
AI summary
System, assemblies, and methods for cathodic protection of one or more components of an oil and gas well may include an anode comprising an anodic coating on a surface of at least one first component of the oil and gas well. A cathode may comprise at least one second component of the oil and gas well, where the anode is configured to at least partially inhibit corrosion of the cathode.