Frusto-Conical Coupling With Elastic Deformation for High Torque
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Solution Overview
Problem
Existing couplings for deep well drilling and oil/gas reservoirs face challenges in handling high torque, pressure resistance, and friction losses, particularly in extended-reach drilling, where traditional threaded connections are inefficient and prone to deformation under repetitive loading cycles.
Innovation Solution
A coupling assembly featuring a 'Key-Loc' design with pin and box surfaces comprising protruding and recessed portions, allowing for axial engagement without rotation, and a method involving fluid injection to achieve elastic deformation and secure connection, enhancing torque and tensile strength while reducing micro-slip and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional threaded connections are used for deep well drilling, then assembly and disassembly can be achieved through rotational torque, but the connections are prone to deformation under repetitive loading cycles and high torque conditions
Solution Approach 1:
The coupling assembly is divided into distinct pin and box members with separate functional zones: drive portions for torque transmission, sealing portions for fluid containment, and shoulders for positioning. This segmentation allows each component to be optimized for its specific function, improving overall reliability while maintaining structural stability under repetitive loading.
Solution Approach 2:
The coupling assembly incorporates elastic deformation capabilities in the wall structures, allowing dynamic adjustment under varying torque and pressure conditions. The elastic material enables the coupling to absorb and dissipate repetitive loading cycles without permanent deformation, enhancing both reliability and structural stability.
2Loss of energy
If premium couplings with thinner wall thicknesses are used to reduce hydrodynamic drag, then fluid flow resistance decreases, but the demand on tongs increases to avoid coupling deformation
Solution Approach 1:
The coupling assembly utilizes composite construction with elastic material components combined with rigid structural elements. This allows the wall thickness to be reduced for lower hydrodynamic drag while the elastic material provides the necessary strength and deformation tolerance to prevent failure under tong engagement forces.
Solution Approach 2:
The coupling design changes the material parameters by incorporating elastic materials with specific stress-strain characteristics. This allows thinner walls to maintain adequate strength through material property optimization rather than relying solely on increased thickness, reducing hydrodynamic drag while maintaining coupling strength.
3Strength
If higher make-up torque is required for premium connections, then connection security improves, but radial clamp force from iron roughneck increases causing potential deformation
Solution Approach 1:
The elastic material in the coupling assembly dynamically responds to radial clamp forces by deforming elastically rather than plastically. This allows the coupling to withstand the increased radial forces from higher make-up torque while maintaining connection strength, as the elastic deformation is reversible and does not lead to permanent damage or failure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coupling assembly provides improved axial/tensile strength, bidirectional torque capability, and reduced friction losses, enabling efficient connection and disconnection of elongated elements like drill pipes without rotational motion, suitable for demanding drilling conditions and reducing operational costs.
Implementation Method 1
a first member (5) and a second member (6) configured for mating engagement, wherein the first member comprises a pin member (5) and the second member comprises a box member (6), and wherein at least one of the pin member and the box member is elastic
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A coupling assembly for elongate elements (1, 2) comprises a pin member (5) and a box member (6), said pin and box members having complementary and respective frusto-conical pin and box mating surfaces (12, 13). A bore (9; 9') has as a first opening a port (9a) configured for connection to an injection fluid reservoir (10) and a second opening (9b) penetrating the pin mating surface (12) or the box mating surface (13). The surfaces (12, 13) may be plain surfaces without helical threads or other pronounced protrusions configured for mating engagement, but comprise a textured finish in order to augment static friction between the surfaces (12, 13) when the surfaces are connected. A region (Rb) of the box surface (13) comprises a wall thickness (ta) which is less than the thicknesses (tb, tc) of the adjacent box walls; and/or a region (Rp) of the pin surface (12) comprises a wall thickness (td) which is less than the thicknesses (te, tf) of the adjacent pin walls; and/or a region (Rb) of the box surface (13) comprises a material of a lower modulus of elasticity than the material of a corresponding region (Rp) of the pin surface (12), or vice versa.