OCTG Threaded Joint Testing for Accurate Seizure Resistance
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Solution Overview
Problem
Existing methods for evaluating the seizure resistance of threaded joints for oil country tubular goods using short pins fail to accurately simulate the conditions of actual well use, leading to inaccurate evaluations of new connection designs, surface treatments, and lubrication methods.
Innovation Solution
A make-up/break-out evaluation method using a pin shorter than the actual length, with a weight attached to simulate the self-weight of the actual pin, and an initial set position where multiple crests are exposed, allowing for a more severe test condition that replicates the misalignment and backlash observed in actual wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a short pin is used for make-up/break-out testing, then the test can be performed in limited facilities and with reduced cost and time, but the evaluation does not accurately reflect actual well conditions including misalignment and backlash
Solution Approach 1:
The patent applies parameter changes by modifying the initial set position parameter - specifically setting it to a loose condition where multiple crests (5 or more) are exposed from the box end face. This parameter change simulates the misalignment and backlash conditions of actual well operations, enabling accurate seizure resistance evaluation using short pins without requiring full-length pins.
2Measurement precision
If a long pin with actual length is used for testing, then the evaluation more closely reflects actual well conditions, but facilities are limited and more cost and time are required
Solution Approach 1:
The patent extracts the essential functional requirements of actual well conditions (misalignment and backlash) from the full-length pin configuration and implements them through specific test parameters: using a short pin with an initial set position where 5 or more crests are exposed. This extraction allows the test to capture the critical failure modes without requiring the full-length pin infrastructure.
3Measurement precision
If the initial set position is set to a loose condition with multiple exposed crests, then misalignment and backlash of actual wells are simulated, but the make-up process becomes more severe
Solution Approach 1:
The patent applies preliminary anti-action by pre-setting the initial position to a loose condition with multiple exposed crests before make-up begins. This preliminary configuration anticipates and reproduces the misalignment and backlash conditions that occur during actual well operations, ensuring the test evaluates seizure resistance under representative severe conditions without requiring actual field deployment.
Data Source
AI summary
A make-up/break-out evaluation method that makes it possible to evaluate the seizure resistance of a threaded joint for oil country tubular goods accurately without performing a test using a threaded joint with an actual length. When performing test with respect to the threaded joint for oil country tubular goods formed by attaching a pin lower portion to box upper portion with its axis directed vertically, a test pin formed by a pin shorter than an evaluation target pin used as test pin; a weight attached to test pin upper portion; mass of the weight is equal to or greater than a mass obtained by subtracting the test pin mass from the evaluation target pin mass; an initial set position for test pin is set where test pin five crests or ¼ of all test pin crests, whichever is greater, or more are exposed from the box upper end face.