Multi-start Thread Connection for Downhole Tool Torque Transmission
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Solution Overview
Problem
Existing threaded couplings in oilfield downhole tools face issues with torque transmission, as they can become damaged due to over-torquing and require significant shoulder load, leading to inefficiencies in energy transfer and longer make-up and break-up times.
Innovation Solution
The use of multi-start thread connections between torque transmitting members reduces induced shoulder load, enhancing torque capacity and allowing for faster connection and disconnection, while maintaining alignment accuracy through helically wound intertwined threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional single-start thread connections are used, then the structure is simple and easy to manufacture, but the torque capacity is limited and shoulder load is high causing damage risk
Solution Approach 1:
The thread connection is segmented into multiple independent starts (e.g., two-start, three-start threads), where each start acts as an independent torque transmission path. This segmentation distributes the total torque across multiple threads, reducing the load on each individual thread and increasing overall torque capacity without requiring a single oversized thread.
Solution Approach 2:
The invention transitions from a single-thread configuration to a multi-start thread configuration, adding the dimension of multiple helical paths. This dimensional change allows the connection to handle higher torques by utilizing multiple intertwined threads that wrap around the fastener in parallel, effectively increasing the load-bearing capacity through spatial distribution.
2Productivity
If conventional thread connections are used, then the make-up and break-up times are long, but the connection is reliable
Solution Approach 1:
The multi-start thread configuration segments the engagement process into multiple parallel paths, allowing the connection to be made and broken more quickly. Since multiple threads engage simultaneously rather than sequentially, the overall make-up and break-up times are reduced while maintaining connection reliability through the distributed load path.
Solution Approach 2:
The multi-start thread design provides excessive thread engagement paths beyond what a single-start thread would provide. This partial redundancy ensures that even if one thread path experiences issues, the other paths maintain the connection, thereby enhancing reliability while enabling faster operation through parallel engagement.
3Power
If multi-start thread connections are used, then torque capacity increases and connection speed improves, but the thread structure becomes more complex
Solution Approach 1:
The multi-start thread connection serves multiple functions simultaneously: it transmits torque, provides alignment, and enables fast connection/disconnection. The same multi-start thread structure that increases torque capacity also facilitates faster make-up and break-up times, making the design universally beneficial across multiple performance dimensions despite the increased geometric complexity.
Solution Approach 2:
The invention merges multiple thread starts into a single integrated fastener structure, combining several torque transmission paths into one unified component. This merging approach achieves high torque capacity and fast operation without requiring multiple separate fasteners or complex assembly mechanisms, thereby managing complexity through integration rather than multiplication of parts.
4Object-affected harmful factors
If conventional thread connections are used, then the shoulder load is high causing potential damage, but the design is straightforward
Solution Approach 1:
The multi-start thread configuration segments the shoulder load across multiple thread starts, reducing the concentrated stress at any single point. This segmentation distributes the mechanical load more evenly throughout the fastener structure, minimizing the risk of shoulder damage while maintaining manufacturing feasibility through standard multi-start threading processes.
Data Source
AI summary
A wellbore apparatus includes a first component having a first element and a second component having a second element. The first component and the second component are connected by a multi-start thread connection and the first element and the second element being operatively connected to one another.