Sucker Rod End Fitting Geometry for Higher Fluid Flow
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Solution Overview
Problem
Existing end fittings for sucker rod strings in well pumps are too large in diameter, restricting fluid flow and not optimized to handle the forces and conditions within oil and gas wells effectively.
Innovation Solution
The design of a sucker rod end fitting with a unique geometry that reduces the outer diameter while maintaining structural integrity, featuring a series of wedge-shaped voids and varying interior surface angles to securely attach fiberglass rods and allow for better fluid flow, achieved through a combination of a cylindrical body with a solid coupling and annular receptacle portions and a pin portion with threads for connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outer diameter of end fittings is reduced to improve fluid flow, then fluid flow in the annulus area is enhanced, but the ability to handle forces and maintain structural integrity is compromised
Solution Approach 1:
The end fitting is segmented into multiple functional zones with different interior surface angles (first angled portion, second angled portion, transition area) that perform different functions. The wedge portions are segmented and spaced apart to create multiple annular, wedge-shaped voids that collectively provide mechanical interlocking while allowing fluid flow. This segmentation allows the fitting to maintain strength through distributed load paths while reducing overall diameter.
Solution Approach 2:
Different portions of the interior surface have different angles optimized for their specific functions: the first angled portion (30-45 degrees) optimizes epoxy distribution, the second angled portion (10-30 degrees) provides mechanical interlocking, and the transition area (5-10 degrees) ensures smooth epoxy flow. This local optimization of surface properties allows the fitting to achieve both reduced diameter and maintained structural integrity.
2Adaptability or versatility
If the outer diameter of end fittings is reduced by 9% to deploy in smaller tubing, then adaptability to different well configurations is improved, but the force handling capacity is reduced
Solution Approach 1:
The invention transitions from a traditional uniform-cylinder geometry to a complex multi-angled geometry with wedge portions arranged in specific patterns. This dimensional reconfiguration of the interior space allows the outer diameter to be reduced by 9% while the internal wedge structures maintain force handling capacity through three-dimensional mechanical interlocking.
3Manufacturing precision
If the interior surface angles are optimized for epoxy flow (5-15 degrees), then manufacturing precision and epoxy distribution are improved, but the mechanical interlocking capability is reduced
Solution Approach 1:
The interior surface is segmented into distinct angular zones: a first angled portion (30-45 degrees) for initial epoxy flow and distribution, a second angled portion (10-30 degrees) for mechanical interlocking, and a transition area (5-10 degrees) for final epoxy seating. This segmentation allows each zone to optimize its function without compromising the others.
Solution Approach 2:
The invention uses multi-dimensional angular variation in the interior surface geometry to resolve the contradiction between epoxy flow optimization and mechanical interlocking. By introducing multiple angular dimensions rather than a single uniform angle, the design achieves both precise epoxy distribution and strong mechanical bonding.
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
This design reduces the outer diameter of the end fittings by up to 9% without compromising performance, enhancing fluid flow and allowing deployment in smaller tubing, thereby improving operational efficiency and reducing axial deformation.
Implementation Method 1
The space between the interior wall of the rod receptacle and the external surface of the rod defines a space or annulus which is filled with epoxy or some other initially flowable adhesive similar to epoxy. The epoxy cures into a solid which bonds to the rod and takes the form of a series of wedges that cooperatively engage complementary surfaces in the rod receptacle
Data Source
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AI summary
The disclosure relates to an end fitting attachable to an end of a sucker rod. The end fitting includes a generally cylindrical body including a receptacle portion and a coupling portion along a longitudinal axis. The receptacle portion includes a receptacle extending inwardly from an open end surface of the body along the longitudinal axis for receiving the sucker rod end therein. The receptacle includes a plurality of wedge portions disposed therein and the coupling portion extends from a coupling end surface of the body opposite the open end surface. The wedge portions each have a peak portion, a first angled portion and a second angled portion. Each second angled portion has an angle with respect to the longitudinal axis wherein each angle of the second angled portions increases from the open end surface of the receptacle portion toward the coupling portion of the end fitting.