Wedge Trim Choke Erosion Mitigation
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Solution Overview
Problem
Conventional needle and seat trims in wellhead choke systems suffer from rapid erosion and cavitation due to small throttling areas, leading to increased wear and reduced operational life.
Innovation Solution
A wedge and cage trim configuration with a movable wedge and actuator, providing a larger throttling orifice area that can be adjusted and a separate positive shut-off point, dispersing erosion zones and reducing fluid recirculation and vortices, while incorporating multi-stage pressure drop control to mitigate cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a needle and seat trim configuration is used, then the valve can achieve flow control, but the small throttling area causes rapid erosion and reduced operational life
Solution Approach 1:
The single throttling point of conventional needle and seat trims is segmented into multiple throttling areas distributed across the wedge surface. This segmentation disperses the erosive forces that would otherwise concentrate at one location, thereby reducing erosion rate and extending operational life.
Solution Approach 2:
The invention transitions from a point-based throttling mechanism (needle tip) to a surface-based throttling mechanism (wedge face). By distributing flow restriction across a two-dimensional surface area rather than a zero-dimensional point, the system increases the throttling area and disperses erosion forces.
2Object-affected harmful factors
If the throttling area is increased to reduce erosion, then erosion resistance improves, but the valve complexity increases
Solution Approach 1:
The wedge-shaped member serves multiple functions simultaneously: it provides flow control through its angled surface, acts as a sealing element against the cage, and distributes erosive forces across its surface. This multi-functionality achieves erosion resistance without proportionally increasing valve complexity.
Solution Approach 2:
The invention changes the geometric parameters of the throttling mechanism from a small circular area to a larger angular surface area. By modifying the shape and distribution of the throttling surface, the system achieves better erosion resistance while maintaining a relatively simple mechanical structure.
3Productivity
If fluid pressure drops quickly below vapor pressure, then flow control is achieved, but cavitation occurs causing significant wear
Solution Approach 1:
The pressure drop process is segmented into multiple stages across different regions of the wedge surface. Instead of a single abrupt pressure drop at one point, the flow encounters gradual pressure reductions across the angled surface, preventing sudden cavitation formation.
Solution Approach 2:
The wedge geometry is designed to cushion the pressure drop before it reaches critical levels. The angled surface creates a gradual decompression zone that prevents the fluid pressure from dropping too quickly below vapor pressure, thereby preventing cavitation before it can occur.
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 wedge and cage trim design extends the operational life of choke components by reducing erosion and abrasion, improving debris tolerance, and minimizing cavitation, thereby enhancing the reliability and efficiency of resource extraction systems.
Implementation Method 1
when fluid flows through the restriction created by the trim, the fluid velocity increases and accelerates while pressure drops
Implementation Method 2
if fluid pressure drops quickly to a level that is less than vapor pressure and then subsequently rises quickly to a level greater than vapor pressure, this can cause the sudden formation and collapse of bubbles, known as cavitation
Implementation Method 3
erosion is most heavily concentrated at this throttling point and, therefore, trims having small throttling areas, such as needle and seat trims, tend to be affected by erosion more quickly
Data Source
AI summary
A choke having a trim that includes a wedge-shaped member (“wedge”) and a cage with an opening for receiving the wedge. The wedge includes a first surface and a second surface that is angled with respect to the first surface. As the wedge is positioned into the opening of the cage, the space between the second surface and a third surface inside the opening forms a throttling orifice that restricts the flow of fluid. The size of the throttling orifice is variable depending on the position of the wedge relative to the cage. The trim can provide a positive shut-off point that is separate from the throttling area.