Single-Crystal Choke Cage Openings for Erosion and Stiction Control
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Solution Overview
Problem
Fluid chokes used in oil and gas production experience erosion and cavitation due to particulates and pressure changes, leading to degraded performance over time, with existing materials like tungsten carbide also eroding and increasing friction, which affects control and flow characteristics.
Innovation Solution
A choke design utilizing a cage with openings made of single crystal materials like sapphire or ruby, which provides superior erosion resistance and lower stiction, along with selectively positionable inserts to maintain flow contours and reduce wear, allowing for improved control and flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tungsten carbide material is used in choke openings, then hardness and wear resistance are improved, but friction increases and erosion still occurs over time
Solution Approach 1:
The patent employs a composite structure where a single crystal material (such as sapphire or ruby) is used to form the flow openings within a metal cage body. This composite approach combines the extreme hardness and erosion resistance of single crystal materials with the structural integrity of the metal cage, achieving superior wear resistance while the smooth single crystal surfaces reduce friction compared to conventional tungsten carbide materials.
Solution Approach 2:
The patent changes the material parameter from polycrystalline tungsten carbide to single crystal materials (sapphire, ruby, or other single crystal substances). This parameter change fundamentally alters the surface properties, providing both extreme hardness for erosion resistance and extremely smooth surfaces that minimize friction and stiction, thereby resolving the contradiction between wear resistance and friction.
2Ease of manufacture
If conventional materials are used in choke openings, then manufacturing is easier, but erosion occurs due to particulates and cavitation
Solution Approach 1:
The patent uses a composite construction where single crystal materials are formed into inserts or integrated into a metal cage structure. This approach maintains ease of manufacture by using established metalworking techniques for the cage body while incorporating single crystal inserts that provide superior erosion resistance against particulates and cavitation, thus resolving the contradiction between manufacturability and erosion resistance.
3Adaptability or versatility
If multiple flow passages are provided in the choke, then flow control flexibility is improved, but surface area exposed to erosion increases
Solution Approach 1:
The patent employs single crystal materials to form multiple flow passages within the cage structure. The single crystal material's extreme hardness and erosion resistance protect all flow passage surfaces equally, allowing the design of multiple passages for flow control flexibility without increasing overall erosion vulnerability. Each passage benefits from the protective properties of the single crystal material.
Solution Approach 2:
The patent applies single crystal material specifically to the flow passage surfaces where erosion occurs, providing localized protection exactly where needed. This local quality approach ensures that the critical flow control surfaces have maximum erosion resistance while maintaining the flexibility to design multiple passages for versatile flow control.
4Ease of operation
If blocking mechanism is spaced from the wall to allow leakage, then full closing is prevented, but flow control precision is reduced
Solution Approach 1:
The patent changes the surface parameter of the blocking mechanism and cage surfaces by using single crystal materials, which provide extremely smooth surfaces. This reduces stiction and friction, allowing the blocking mechanism to seat more precisely against the cage wall with minimal leakage, thereby improving both the ease of operation and the precision of flow control simultaneously.
Data Source
AI summary
A choke includes a cage having a plurality of openings extending therethrough, a first fluid port and a second fluid port, the openings in the cage fluidly interposed between the first and second fluid ports, and a selectively positionable blocking member positioned with respect to the openings to selectively overlie all of a portion of the openings, wherein the surface of the opening extending through the cage are a single crystal material. The single crystal material may be provided as an insert, having an opening therethrough, secured in position with respect to the cage.