Tubular Threadform Relief Geometry to Prevent Hydraulic Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tubular connectors in the oil and gas industry face challenges with hydraulic locking due to insufficient volume for thread compound, leading to inaccurate torque readings and potential premature failure, especially in deep and complex wells with increased tensile and torsional loads.
Innovation Solution
Designing a tubular connection threadform with thread compound relief spaces that extend along the entire axial length, allowing for a substantial volume to accommodate thread compound and providing flexibility in uneven application, while maintaining high tensile and pressure strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thread compound is applied to fill voids between threads, then lubrication and sealing are improved, but hydraulic locking occurs when void volume is insufficient
Solution Approach 1:
The threadform is segmented into distinct functional zones: a first portion with a first flank angle for engagement, and a second portion with a second flank angle for relief. This segmentation allows different sections of the thread to serve different purposes - one for mechanical engagement and another for accommodating thread compound volume
Solution Approach 2:
Different portions of the threadform have different geometric properties. The first portion has specific flank angles optimized for strength and engagement, while the second portion has different flank angles optimized for creating relief volume. This local differentiation of geometric quality allows simultaneous optimization of both mechanical performance and compound accommodation
2Measurement precision
If thread compound volume is increased to prevent hydraulic locking, then accurate torque readings are achieved, but connection complexity increases
Solution Approach 1:
The threadform parameters are changed by introducing a second portion with different flank angles (second flank angle) compared to the first portion (first flank angle). This parameter change in the geometric configuration creates additional volume for thread compound without fundamentally changing the basic thread structure, thereby preventing hydraulic locking while maintaining manufacturing feasibility
3Quantity of substance
If threadform is designed with crest to root relief, then thread compound volume is maximized, but manufacturing difficulty increases
Solution Approach 1:
The threadform is divided into a first portion and a second portion along its axial length. The first portion maintains standard thread geometry for engagement, while the second portion incorporates the crest to root relief geometry. This segmentation allows the complex relief feature to be localized to only the portion where it is needed, simplifying the overall manufacturing process compared to applying relief throughout the entire threadform
Data Source
AI summary
A connection includes a first tubular member having a first screw threadform defined by a first plurality of crests, roots, and flanks, where each flank separates each crest from each root. The connection also includes a second tubular member having a second screw threadform defined by a second plurality of crests, roots, and flanks, where each flank separates each crest from each root. The crests and roots are substantially axial to the tubular members and the flanks are substantially radial to the tubular members. The first tubular member and the second tubular member are configured to connect when the first threadform engages with the second threadform. Thread compound relief spaces are formed between the first plurality of crests and the second plurality of roots when the first and second tubular members connect.