Holddown Assembly with Segmented Holding and Sealing Elements
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Solution Overview
Problem
Conventional holddown assemblies for downhole pumps in oil and gas wells face issues with sealing elements that are not durable enough to withstand multiple seatings, leading to leakage and reduced holding force over time, requiring frequent replacements and limiting operational cycles.
Innovation Solution
A holddown assembly featuring resilient, durable holding elements made of materials like steel or copper nickel tin alloy, which elastically deform to secure the pump without damaging softer sealing elements, allowing for multiple seating cycles without force degradation and reducing the need for element replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing elements are made of soft materials suitable for fluid sealing, then sealing effectiveness is improved, but durability and holding force are reduced
Solution Approach 1:
The invention divides the holddown assembly into two distinct functional components: holding elements made of durable material (steel, copper nickel tin alloy) for axial securing, and sealing elements made of softer material for fluid sealing. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
Different materials with appropriate properties are assigned to different parts of the holddown assembly: the holding elements use hard, durable materials to withstand repeated seatings and provide consistent holding force, while the sealing elements use softer materials optimized for creating effective fluid seals against the bore wall.
2Device complexity
If sealing elements are used to both seal and anchor the pump, then device complexity is reduced, but durability and operational lifespan are reduced
Solution Approach 1:
The invention separates the sealing and anchoring functions into distinct elements within the holddown assembly, allowing the sealing elements to be protected from the mechanical stresses of repeated seatings while the holding elements are specifically designed to withstand these stresses.
Solution Approach 2:
The holding elements act as intermediaries that bear the mechanical load of repeated seatings and unseatings, protecting the sealing elements from damage while still enabling the pump to be securely anchored and fluidly sealed.
3Strength
If durable materials are used for sealing elements, then holding force and durability are improved, but sealing effectiveness is reduced
Solution Approach 1:
The invention applies the principle of local quality by assigning different material properties to different components: holding elements use durable, strong materials (steel, copper nickel tin alloy) optimized for mechanical strength and resistance to repeated seatings, while sealing elements use softer materials optimized for creating effective fluid seals.
4Ease of manufacture
If the same material is used for both holding and sealing functions, then manufacturing complexity is reduced, but performance in both functions is compromised
Solution Approach 1:
The invention implements local quality by specifying different materials for holding and sealing elements based on their specific functional requirements, rather than using a single material for both functions. This allows each component to perform optimally in its designated role.
Solution Approach 2:
The holddown assembly uses composite construction with holding elements made of durable materials (steel, copper nickel tin alloy) and sealing elements made of softer sealing materials, combining the advantages of different material properties in a single assembly.
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 provides consistent axial seating and unseating forces over many cycles, minimizing damage to sealing elements and reducing the frequency of replacements, thereby enhancing the operational lifespan and reliability of the holddown assembly.
Implementation Method 1
The at least one holding element is preferably sized and configured to only elastically deform when seated in the seating tubular
Implementation Method 2
a pre-determined axial unseating force must be applied in order to overcome the frictional force between the at least one holding element and the bore wall of the seating tubular
Implementation Method 3
The at least one sealing element is made of a resilient material that is softer than that of the at least one holding element and is configured to sealingly engage with the bore wall of the seating tubular and prevent wellbore fluid from flowing thereby
Data Source
AI summary
A holddown assembly is provided for axially securing a pump in a wellbore. The assembly has a mandrel having at least one resilient holding element and at least one resilient sealing element. The holding elements are made of a durable material and configured to require a pre-determined seating force to seat the assembly in a seating tubular, and a pre-determined unseating force to unseat the assembly. The holding elements are configured to elastically deform when seated, such that the pre-determined seating and unseating force does not change significantly even over many seating/unseating cycles. The sealing elements are configured to sealingly engage with the seating tubular to prevent wellbore fluid from flowing thereby. As the sealing elements are only used for forming a fluid seal, and not for securing the pump, damage to the sealing elements as a result of repeated seatings and unseatings is mitigated.