Intermediate-Shoulder Tubular Thread Connection for Axial Load Sealing
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Solution Overview
Problem
Existing threaded tubular connections in oil wells face challenges in maintaining mechanical strength and fluid sealing under varying stresses, particularly compressive loads, while ensuring compatibility with borehole dimensions and fluid flow.
Innovation Solution
The design features a threaded tubular connection with offset inner and outer threaded portions on both male and female components, featuring tapered teeth with crest and root surfaces, and a mated shoulder contact area that occupies a specific ratio of the nominal cross-sectional area, enhancing compressive load resistance without compromising fluid flow or borehole compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the threaded portions are tapered at a greater angle, then the connection strength is improved, but the fluid flow capability and borehole compatibility deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the taper angle of the threaded portions to be approximately 6% or less, and by specifying that the crest and root surfaces be flat and parallel rather than tapered. This parameter optimization resolves the contradiction by maintaining sufficient connection strength while preserving fluid flow capability and borehole compatibility that would be compromised by more aggressive taper angles.
2Force
If the mated shoulder contact area ratio is increased, then the axial load resistance is improved, but the complexity of achieving precise geometric alignment increases
Solution Approach 1:
The patent optimizes the mated shoulder contact area ratio to fall between 15-25% of the nominal cross-sectional area. This parameter range achieves effective axial load resistance while avoiding the geometric complexity that would arise from larger contact areas requiring more precise alignment tolerances.
Solution Approach 2:
The patent applies local quality by concentrating the load-bearing function specifically at the mated shoulder interface rather than distributing it throughout the entire connection. This localized approach allows the majority of the connection geometry to remain simple while achieving the required axial load resistance at the critical interface.
3Strength
If the tubular component diameter is reduced at the male threading end, then the material thickness for strength is improved, but the overall assembly size and borehole compatibility worsen
Solution Approach 1:
The patent optimizes the diameter reduction parameter at the male threading end to achieve sufficient material thickness for strength while maintaining overall assembly size compatibility with borehole dimensions. The controlled parameter change ensures the thinned section provides adequate wall thickness for the threaded connection without excessive overall diameter reduction that would compromise borehole compatibility.
Data Source
AI summary
A threaded tubular connection comprises a first tubular component and a second tubular component. The first tubular component includes a female portion defined on an interior surface of the first tubular component. The female portion includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the first tubular component by a first shoulder. The second tubular component includes a male portion defined on an exterior surface of the second tubular component. The male portion is to be inserted into the female portion, and includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the second tubular component by a second shoulder. The second shoulder is to abut the first shoulder once the male portion is connected to the female portion.