Self-Locking Tubular Threaded Joint for High-Torque Sealing
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Solution Overview
Problem
Existing threaded connections for oilfield tubulars face challenges in maintaining high torque resistance while ensuring sealability and structural integrity, particularly in deep water wells, where elevated torque is required without compromising the connection's performance over multiple make-up and breakout cycles.
Innovation Solution
A threaded joint design featuring trapezoidal dovetail threads with varying and non-varying zones, where the male and female threaded zones have a specific axial gap and lead profiles, allowing for self-locking engagement and enhanced torque resistance, while maintaining a metal-to-metal seal and minimizing stress on the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If threaded connections are designed for high torque resistance, then torque capacity is improved, but sealability and structural integrity may be compromised
Solution Approach 1:
The threaded connection is divided into two distinct zones: a varying zone with self-locking threads for torque resistance and a non-varying zone for sealability. This segmentation allows each zone to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different thread profiles are applied to different portions of the connection. The varying zone uses trapezoidal dovetail threads with specific lead profiles for high torque capacity, while the non-varying zone maintains consistent thread geometry for reliable sealing, ensuring each local area has the quality needed for its function.
2Force
If self-locking engagement is achieved through varying thread zones, then torque resistance is improved, but make-up procedure complexity increases
Solution Approach 1:
The thread design incorporates a varying zone that automatically engages in a self-locking manner during the make-up process. The geometry of the varying threads with different leads pre-determines the engagement sequence, eliminating the need for complex external locking mechanisms or specialized make-up procedures.
3Force
If elevated torque capacity is required for special applications, then torque resistance is improved, but the connection may fail to maintain sealability under rotation
Solution Approach 1:
The connection is segmented into a varying zone for torque absorption and a non-varying zone for sealing. This separation ensures that the sealing function is isolated from the high-stress torque-bearing varying threads, allowing the seal to remain intact even when the connection is subjected to elevated torques during rotation operations.
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 provides a balanced solution for high torque resistance, precise seal positioning, and predictable make-up procedures, reducing the risk of premature failure and maintaining seal integrity even under elevated torque conditions.
Implementation Method 1
the threaded zones comprise a varying zone where the threads have a varying width and a non-varying zone, adjacent to the varying zone, where the threads have a constant width, the varying zone of the male threaded zone being made up with the varying zone of the female threaded zone, and non varying zone of the male threaded zone being made up with the non varying zone of the female threaded zone
Implementation Method 2
Trapezoidal threads comprise load flank, stab flank, root and crest, such that between two adjacent roots, load flank, stab flank and crest define a sensibly trapezoidal shape
Implementation Method 3
both male and female threaded zones comprising respectively a varying zone where thread have varying width, and a non varying zone, adjacent to the varying zone, where thread have a constant width
Data Source
AI summary
Threaded joint, comprising a first and a second tubular component (C1, C2), the first tubular component comprising a first pipe body (10) and a male end (1), the male end comprising a distal surface (17) and a male threaded zone (13) at a male end, the second tubular component comprising a second pipe body (20) and a female end (2) comprising a distal surface and a female threaded zone (23), both male and female threaded zones (13, 23) comprising respectively a varying zone where thread have varying width, and a non varying zone, adjacent to the varying zone, where thread have a constant width, the varying zone of the male threaded zone being made up with the varying zone of the female threaded zone, and non varying zone of the male threaded zone being made up with the non varying zone of the female threaded zone, a thread profile of the male and female threaded zones being trapezoidal and a pin external shoulder (37) of the male end is in axial abutting contact against a corresponding abutment surface (42) of the female distal surface.