Wedge Threaded Casing Connection With Pin-End Annular Recess
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Solution Overview
Problem
Existing wedge threaded connections in wellbores face mechanical wear and sealing issues due to the small annular space between tubing and casing, leading to potential contact and damage from drill strings and production tubing, especially in smaller diameter wellbores where increasing the casing diameter is not feasible.
Innovation Solution
Incorporating an internal annular recess in the pin-end of the wedge connection, which provides flexibility and reduces mechanical wear by allowing tool joints and couplings to move without contacting the inner diameter of the casing, while maintaining mechanical strength and sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the casing diameter is increased to reduce mechanical wear and provide more annular space, then the annular space between tubing and casing increases, but the wellbore diameter requirement increases which is not feasible in smaller diameter wellbores
Solution Approach 1:
The patent applies local quality by creating an internal annular recess at the pin-end of the wedge connection that provides localized flexibility and wear compensation. This recess allows the pin-end to move radially within the recess space, effectively creating a local buffer zone that increases the functional annular space without requiring an increase in overall casing diameter. The recess is positioned specifically at the pin-end where tool joints and couplings interact with the casing inner diameter, providing targeted protection against mechanical wear.
2Adaptability or versatility
If the annular recess is made larger to provide more flexibility and reduce wear, then the flexibility and wear protection improve, but the structural strength of the pin-end may be compromised
Solution Approach 1:
The patent applies segmentation by dividing the pin-end structure into two functional zones: the upper portion maintains full wall thickness for structural strength and load-bearing capacity, while the lower portion incorporates the internal annular recess that provides flexibility and wear compensation. This segmentation allows each zone to optimize its function without compromising the other - the upper zone provides strength while the recessed zone provides adaptability.
3Reliability
If the internal annular recess is added to reduce mechanical wear and improve flexibility, then wear protection and flexibility improve, but the manufacturing complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting material from the lower portion of the pin-end to create the internal annular recess. This removed material creates the flexible zone that allows radial movement and wear compensation. The extraction is performed in a controlled manner, removing only the necessary amount of material to provide flexibility while maintaining the structural integrity of the upper pin-end portion.
Data Source
AI summary
A tubular connection includes a first joint of casing having an integral box end with an internal female wedge threaded zone having wedge threads disposed on a portion of the integral box end, and a second joint of casing having an integral pin end with an external male wedge threaded zone having wedge threads disposed on a portion of the integral pin end. The external male wedge threads engage with the internal female wedge threads. The second joint of casing has an internal diameter D1, and also includes an internal annular recess with an internal diameter D2. D2 is greater than D1, and the annular recess is disposed longitudinally along an inner surface of the second joint of casing. The annular recess is positioned radially adjacent to a portion of the external male threads disposed on a lower portion of the pin end.