Multiple-Tapered Drill String Threads for Deep Engagement and Torque
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Solution Overview
Problem
Low taper threaded connections in drill string components face challenges in handling and threading due to shallow engagement, leading to increased time and repair costs, and multi-step threads have poor torsional energy retention and are difficult to manufacture and control.
Innovation Solution
A multiple tapered threaded connection design with varying tapers and transitional threads to enhance engagement and torque capability, allowing for deeper stabbing and reduced thread damage during assembly, while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low taper threaded connections are used, then handling and threading become easier, but engagement depth is insufficient leading to increased thread damage and repair costs
Solution Approach 1:
The threaded connection is divided into multiple sections with different tapers: a first section with a first taper for initial engagement and stabbing, and a second section with a second taper for deep engagement and torque transmission. This segmentation allows each section to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different portions of the threaded connection have different taper characteristics tailored to their specific functions. The first section has a taper optimized for ease of stabbing and initial engagement, while the second section has a taper optimized for deep engagement and torque capability, ensuring each local area has the quality needed for its purpose.
2Loss of time
If low taper threaded connections are used, then assembly time is reduced, but thread damage increases leading to higher repair costs
Solution Approach 1:
The connection is segmented into a first section for quick stabbing and initial engagement, and a second section for secure deep engagement. This allows the connection to be made quickly while ensuring adequate engagement depth to prevent thread damage.
Solution Approach 2:
The taper parameter is changed between sections: the first section has a taper that facilitates rapid stabbing and engagement, while the second section has a different taper that ensures sufficient engagement depth and distributes loads to prevent thread damage, thus reducing repair needs.
3Strength
If multi-step threads are used, then torsional energy retention is improved, but manufacturing complexity and control difficulty increase
Solution Approach 1:
Rather than using complex multi-step threads with multiple starts, the connection is segmented into sections with different tapers along a single continuous thread. This achieves torsional energy retention through proper load distribution while maintaining manufacturing simplicity and control.
Solution Approach 2:
The thread structure has different local qualities in different sections: the first section has taper characteristics optimized for engagement, while the second section has taper characteristics optimized for torque transmission. This local differentiation achieves the desired strength without requiring complex multi-step thread designs.
Data Source
AI summary
A threaded connection between adjacent drill string components comprises a threaded female connection end adapted to receive a correspondingly threaded male connection end, the two ends each having first and second portions of different tapers. Tubular members, drill string tools and other drill string components comprising the female or male ends described herein are also provided.