Tapered Pipe Connection Threads for High-Compression Well Completions
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Solution Overview
Problem
Tubular completions in oil wells and wells with high gas-oil ratios experience undesired TCA pressure due to connections with reduced compression capacity, often leading to buckling under compression loads and loss of connection integrity, requiring costly well interventions.
Innovation Solution
A pipe connection system featuring pin and complementary box connectors with a tapered wall and multiple pin threads, where the pitch between projections changes along the axial length, enhancing compression capacity. The connectors include a last thread portion with a specific load flank angle, increased width, and height, along with a resilient seal for improved integrity and sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional connections are used in tubular completions, then the device complexity is reduced, but the compression capacity is insufficient leading to connection failure under high compression loads
Solution Approach 1:
The connection system is divided into distinct functional components: an outer connector with box threads, an inner connector with pin threads, and a resilient seal. The box threads and pin threads are segmented with specific geometric features including varying pitch along the axial length, different flank angles at different locations, and rounded edges. This segmentation allows each component to be optimized for specific functions (engagement, load bearing, sealing) while maintaining overall structural integrity under compression loads.
Solution Approach 2:
Different regions of the thread structure have different geometric properties tailored to local functional requirements. The pitch between thread projections varies along the axial length, being coarser at certain regions and finer at others. The flank angles differ between the first and last engaged threads, with the last thread portion having a smaller included angle optimized for load bearing. This local differentiation of geometric qualities enables the connection to handle high compression loads effectively while maintaining ease of assembly.
2Reliability
If connections with reduced compression capacity are used, then the manufacturing cost is reduced, but connection integrity is lost under compression loads requiring costly well interventions
Solution Approach 1:
The thread geometry parameters are specifically optimized to achieve high compression capacity. The included angle of the last thread portion is set to a smaller value (resulting in a larger flank angle) compared to conventional connections, which increases the contact area and load-bearing capacity. The pitch between thread projections is varied along the axial length, with specific ratios between different sections. These parameter changes enhance connection integrity under compression while maintaining manufacturability through standard machining processes.
3Strength
If conventional thread designs are used, then the ease of operation is maintained, but thread jump-out occurs under high compression loads
Solution Approach 1:
The thread structure is designed with preliminary geometric features that prevent jump-out before it occurs. The last thread portion has a smaller included angle and larger flank angle, creating a self-locking effect under compression loads. The rounded edges on thread projections and the specific pitch distribution along the axial length are pre-configured to distribute loads evenly and prevent stress concentration. These preliminary design features ensure thread engagement integrity without requiring complex assembly procedures or special tools.
Data Source
AI summary
A pipe connection system for use in a well completion system includes an inner connector and an outer connector. The inner connector includes a tapered wall and multiple pin threads arranged along the tapered wall, wherein a pitch between projections formed by the multiple pin threads changes along an axial length of the pin connector. The outer connector is formed complementary to the inner connector along at least a portion of the outer connector.