Header Ring with Annular Undercut for Downhole Pump Seals
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Solution Overview
Problem
Reciprocating pump seals, particularly header rings, face significant wear and tear due to the abrasive nature of proppants used in hydraulic fracturing, along with varying fluid pHs and high pressures, leading to seal failure and inefficiency, as existing materials are either too abrasive or insufficiently secure, causing frictional issues and mechanical challenges during replacement.
Innovation Solution
A header ring with a unique geometry and material composition, featuring an outwardly extending annular undercut, inwardly sloped and flat portions, and a softer outer wall with an inwardly extending annular ledge, formed from nonabrasive elastomers with varying durometer hardness, providing improved sealing and self-cleaning capabilities through radial force and automatic surface cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomeric composite seals are used to seal the plunger, then sealing capability is improved, but frictional wear on the stuffing box increases due to abrasiveness
Solution Approach 1:
The seal assembly incorporates different materials for different components: the header ring uses a softer, non-abrasive elastomer (e.g., Hypalon with Shore A 55-65) to contact the stuffing box and minimize wear, while the pressure ring uses a harder elastomeric composite for sealing against the plunger. This local differentiation allows each component to perform its specific function optimally without causing harm to other parts.
2Reliability
If the gland nut is tightened to secure the seal assembly, then sealing pressure is improved, but the header ring may be extruded back into the fluid end causing seal failure
Solution Approach 1:
The header ring includes a recessed portion that engages with a protrusion on the plunger end, creating a mechanical interlock that prevents the header ring from being extruded into the fluid end during tightening. This preliminary structural design counteracts the extrusion force before it can cause damage.
3Ease of operation
If the gland nut is loosened to allow seal movement, then ease of installation is improved, but the seal assembly moves back and forth causing wear and eventual failure
Solution Approach 1:
The seal assembly includes a retaining ring that mechanically secures the header ring and pressure ring in position within the stuffing box before operation begins. This preliminary mechanical constraint prevents unwanted movement during operation, eliminating wear caused by back-and-forth motion while maintaining ease of installation and replacement.
4Productivity
If smaller proppant particles are used in hydraulic fracturing, then fracture filling efficiency is improved, but abrasive wear on the header ring increases significantly
Solution Approach 1:
The invention changes the material parameter of the header ring from traditional hard elastomeric composites to softer, more abrasion-resistant materials such as Hypalon with specific Shore A hardness (55-65). This parameter change allows the header ring to withstand the increased abrasion from smaller proppant particles while maintaining its sealing function.
5Loss of time
If seals are replaced in the field, then operational continuity is improved, but proper cleaning of contacting surfaces becomes difficult leading to sealing problems
Solution Approach 1:
The header ring design incorporates self-aligning and self-seating features through its geometric configuration, including the recessed portion and engagement surfaces. During installation, the seal assembly automatically positions itself correctly on the plunger, reducing the need for precise manual alignment and cleaning operations during field replacement.
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 solution enhances seal durability and longevity by reducing wear on the stuffing box, maintaining pressure integrity, and facilitating easier replacement by automatically cleaning surfaces, thereby improving the sealing performance and extending the operational life of the seal.
Implementation Method 1
The outer wall portion is formed from a nonabrasive elastomer
Implementation Method 2
The outer wall portion and the inner wall portion are each formed of an elastomer having a durometer of between about 70 and 95 Shore A
Data Source
AI summary
A new header ring useful in downhole packing sets automatically cleans the cylinder plunger wall during use and forms an improved seal having long duration. The new header ring has a ring shaped body. The body includes a side wall defining an open top, an open bottom, and an inner wall portion with an inner wall surface for contacting a plunger. The inner wall portion includes an outwardly extending annular undercut, which defines an overhang and radius that helps wipe clean the plunger wall and form a better seal. The body also has an outer wall portion with an outer wall surface for contacting a stuffing box wall. The outer wall has a flat upper portion, a flat lower portion, and an outwardly sloped annular middle portion connecting the top and lower portions. The outer wall also has an inwardly extending annular ledge formed in its bottom. The inner wall portion is formed from a high wear resistance elastomer, and the outer wall portion is formed from a nonabrasive elastomer.