Self-Locking Threaded Connection for High-Torque Well Sealing
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Solution Overview
Problem
Existing threaded connections for shale gas wells face challenges in providing high torque capacity, fast make-up, cost-effectiveness, and low handling damage risk while maintaining seal performance under varying internal pressures and cyclical fatigue.
Innovation Solution
A threaded connection design featuring a self-locking arrangement with a locking region and a non-locking region, utilizing tapered threads with varying root and crest widths to maximize torque transmission and sealing efficiency without the need for additional sealing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional abutment surfaces are used to achieve make-up torque, then the connection can be made up, but the critical yielding threshold of the abutment surfaces is rapidly reached when too great a make-up torque is applied
Solution Approach 1:
The threaded connection is divided into two distinct regions: a self-locking engagement region with tapered threads for torque transmission, and a non-locking engagement region with parallel threads for sealing and final positioning. This segmentation allows the make-up torque to be applied through the tapered threads rather than relying solely on the abutment surfaces, thereby preventing exceeding the critical yielding threshold of the abutment surfaces.
Solution Approach 2:
The invention introduces a dimensional change by transitioning from a single-region threaded connection to a two-region connection with different thread geometries. The self-locking region uses tapered threads (conical geometry) to provide mechanical interlocking and torque resistance, while the non-locking region uses parallel threads for sealing. This dimensional and geometric differentiation resolves the contradiction by distributing torque loads away from the abutment surfaces.
2Force
If self-locking threads are used to increase torque capacity, then torque transmission is improved, but the manufacturing complexity increases
Solution Approach 1:
The threaded connection is segmented into two functional regions: a self-locking engagement region with tapered threads for high torque capacity, and a non-locking engagement region with parallel threads for sealing and positioning. This segmentation allows the complex self-locking mechanism to be localized to only the portion of the connection where it is needed, rather than requiring the entire threaded connection to be complex.
Solution Approach 2:
The invention applies different thread geometries to different locations along the threaded connection. The self-locking region with tapered threads is applied locally where torque transmission is critical, while the non-locking region with parallel threads is applied where sealing and final positioning are needed. This local differentiation optimizes performance in each region without requiring the entire connection to be complex.
3Reliability
If conventional threaded connections are used, then manufacturing is simpler, but seal performance under varying internal pressures and cyclical fatigue is insufficient
Solution Approach 1:
The threaded connection is segmented into a self-locking engagement region with tapered threads for structural integrity and torque resistance, and a non-locking engagement region with parallel threads that provides enhanced sealing capability under varying internal pressures and cyclical fatigue conditions.
Solution Approach 2:
The invention creates a composite threaded connection structure combining two different thread geometries (tapered and parallel) within a single connection. This composite approach leverages the advantages of both thread types: the tapered threads provide mechanical strength and self-locking, while the parallel threads provide sealing stability under pressure variations and fatigue, achieving superior overall reliability.
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 connection achieves high tension and compression efficiency, maintains seal integrity under high pressures, and reduces manufacturing costs while minimizing handling damage, with a make-up efficiency of at least 100% of the pipe body.
Implementation Method 1
self-locking arrangement in order to provide a locking region and a non-locking region in the threaded connection... the first male threaded portion and the first female threaded portion... cooperation of the first male threaded portion and the first female threaded portion
Data Source
AI summary
A threaded connection comprising: a first tubular component (1) having a first male threaded portion (16) and a second male threaded portion (17), a root width in the first male threaded portion (16) decreasing in a direction oriented a first pipe body (3), the root width being constant in the second male threaded portion (17), the second tubular component (2) comprising a female threaded zone (10) having a first female threaded portion (19) with a root width decreasing in a direction oriented towards a second pipe body (5), the connection being partially made up in a self-locking arrangement in order to provide a locking region (18) and a non-locking region (20), a female distal thread (22) of the locking region (18) has a width such that FDTW/TH>=125%, in which FDTW is a tooth width of the female distal thread (22) of the locking region and TH is the tooth height of said female distal thread (22).