13Cr Tool Coupler Heat Treatment for CO2 Corrosion Resistance
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Solution Overview
Problem
Existing drillrods, including those made of low alloy steel, fail to meet the harsh conditions in modern oil and gas exploration, particularly in CO2-rich environments, leading to low yield and high costs due to corrosion issues, and existing high alloy drillrods face galvanic corrosion when connected with steel couplers.
Innovation Solution
A method for manufacturing a superior 13Cr tool coupler involving forging, stress-relief annealing at 600-700°C, quenching in oil at 950-1000°C, and tempering at 600-650°C, with specific chemical composition and process parameters to prevent galvanic corrosion and achieve a tempered martensitic structure, ensuring no severe corrosion and high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel couplers are used with aluminum alloy or titanium alloy tube bodies, then the drillrod can be manufactured with high strength, but galvanic corrosion occurs between the steel couplers and the aluminum alloy or titanium alloy tube body causing severe corrosions
Solution Approach 1:
The patent applies homogeneity by using 13Cr alloy steel for both the coupler and the tube body, ensuring that the entire drillrod structure is made of the same material composition. This eliminates the galvanic corrosion problem that occurs when dissimilar metals (steel coupler with aluminum alloy or titanium alloy tube body) are connected, while maintaining the high mechanical strength required for drilling operations
2Ease of manufacture
If conventional low alloy steel drillrods are used, then the manufacturing cost is lower, but they fail to fulfill the harsh requirements of well drilling operation in CO2-containing gas fields
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the steel, specifically increasing the chromium content to 12-14% to create a 13Cr alloy steel. This compositional change provides superior resistance to CO2 corrosion and stress corrosion while maintaining manufacturing feasibility and cost-effectiveness for industrial exploration
3Productivity
If nitrogen well-drilling process is employed to achieve high yield, then millions of cubic meters of natural gas per day can be produced, but the drillrod cannot be lifted out to exchange into the oil tube for well completion otherwise the production layer would be contaminated
Solution Approach 1:
The patent applies homogeneity by making the coupler from the same 13Cr alloy steel material as the tube body, eliminating galvanic corrosion and enabling the drillrod to remain in place for the duration of nitrogen well-drilling operations without requiring replacement with oil tubes, thus maintaining high yield while providing operational flexibility
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 method produces a high-quality 13Cr tool coupler resistant to CO2 corrosion, eliminating galvanic corrosion and achieving mechanical strength above 110 ksi, suitable for use in high CO2 gas fields, thereby enhancing drilling efficiency and reducing production costs.
Implementation Method 1
heating the forged blank to 600-700° C. for a stress-relief annealing
Implementation Method 2
quenching
Implementation Method 3
tempering
Data Source
AI summary
The present invention discloses a method for manufacturing a superior 13Cr tool coupler, which method comprises the following steps: manufacturing a blank;forging the blank; heating the forged blank to 600-700° C. for a stress-relief annealing; quenching; and tempering. The present technical solution can produce a superior 13Cr tool coupler which achieves a mechanic feature of 110 ksi.