Downhole Valve Locking Piston for Leak and Cavitation Control
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Solution Overview
Problem
Current downhole valve designs face issues such as leakage due to thermal effects, erosion, and damage from cavitation and miscalibration, particularly when handling high-pressure fluids, and are challenged by large static loads and increased pressure differentials.
Innovation Solution
A valve assembly with compliant valve elements and a locking piston system that maintains sealing contact despite thermal changes and pressure differentials, using springs and a locking piston to manage pressure differentials and prevent cavitation by spacing seal faces to avoid high-velocity fluid impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If valve elements are made rigid to maintain sealing contact, then sealing reliability improves, but thermal expansion and contraction cause leakage
Solution Approach 1:
The valve elements are designed with compliant properties that allow their physical parameters (shape, position) to change in response to thermal expansion and contraction. This compliance enables the sealing surfaces to maintain contact despite temperature variations, resolving the contradiction between rigid sealing and thermal stability
Solution Approach 2:
The valve elements incorporate flexible or compliant materials that can deform to maintain sealing contact. This flexibility allows the valve elements to adapt to thermal changes while preserving the sealing function, addressing both the reliability and stability requirements
2Reliability
If valve elements are positioned close together to improve sealing, then sealing efficiency improves, but cavitation and erosion damage increase
Solution Approach 1:
A locking piston is introduced as an intermediary component between the valve elements. This piston applies controlled force to maintain the valve elements in proper sealing contact while preventing them from being forced too closely together, thereby eliminating cavitation and erosion damage while preserving sealing efficiency
Solution Approach 2:
The locking piston preemptively counteracts the harmful effects of excessive force on the valve elements. By applying controlled compressive force, it prevents the valve elements from being pushed into positions that would cause cavitation and erosion, while still maintaining adequate sealing contact
3Ease of operation
If actuator force is increased to overcome static head pressure, then valve actuation capability improves, but actuator component damage increases
Solution Approach 1:
A locking piston system is introduced that uses hydraulic or mechanical force distribution to reduce the static load on actuator components. The locking piston bears a portion of the pressure differential load, thereby reducing the force requirements on the actuator and stem while maintaining valve actuation capability
Solution Approach 2:
The locking piston acts as a counterbalancing element that offsets the static head pressure load on the actuator. By distributing the pressure differential force, it reduces the net load that the actuator must overcome, thereby protecting actuator components from damage while maintaining operational capability
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 system effectively prevents leakage and cavitation while maintaining sealing integrity, reducing damage to actuation components by managing pressure differentials and ensuring compliant engagement of seal faces, thus enhancing the durability and reliability of downhole valves.
Implementation Method 1
a locking piston in the chamber having a side in pressure communication with the inlet and an opposing side in pressure communication with the outlet, the locking piston being selectively moved into a locking position and biased against an end of the first valve element
Implementation Method 2
valve elements in the chamber each having a seal face, a fluid flow barrier in the chamber formed when seal faces on adjacent valve elements are brought into sealing contact with one another
Implementation Method 3
using springs and a locking piston to manage pressure differentials and prevent cavitation by spacing seal faces to avoid high-velocity fluid impacts
Data Source
AI summary
A bi-directional valve with valve elements having compliant features biasing them together to maintain a sealing interface that defines a fluid communication barrier within the valve. Parting the valve elements from one another removes the sealing interface allow fluid communication across the valve elements. The valve includes a side port and a choke member that selectively blocks fluid flow through the valve when moved adjacent the side port and selectively opens the valve to fluid communication when moved away from the side port. The choke member remains adjacent the side port until the valve elements are spaced a distance apart greater than that at which valve erosion or fluid cavitation occurs. Also included with the valve are systems for counterbalancing forces exerted onto the valve from differential pressures.