Convertible Stem Valve Coupling for Balanced Pressure Operation
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Solution Overview
Problem
Existing valve systems used in downhole drilling and recovery operations face challenges in efficiently managing high pressures, leading to high operational forces and increased costs due to the need for large actuators, as balanced stem valves do not function as surface safety valves and require large, expensive actuators to operate effectively.
Innovation Solution
A system and method for converting a valve between balanced and unbalanced operation modes using a lower stem with variable diameter and lugs that can be axially moved and rotated to align or misalign with anti-rotation pins, allowing for external coupling and decoupling, reducing the need for internal threads and enabling dual operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a balanced stem valve is used to reduce stem thrust and operating forces, then the operating forces are reduced, but the valve cannot function as a surface safety valve requiring large actuators
Solution Approach 1:
The lower stem is designed with a variable outer diameter including lugs that can be positioned in different axial locations. By moving the lugs axially and rotating the lower stem, the valve can dynamically switch between balanced operation mode (lugs aligned with reduced diameter portion) and unbalanced operation mode (lugs misaligned), allowing the same valve to adapt to different operational requirements without requiring separate valves or permanently fixed configurations
Solution Approach 2:
The lower stem is segmented into sections with different diameters, including a reduced diameter portion and lugs with lug diameter larger than adjacent lower stem diameter. This segmentation allows selective engagement with the valve member nut's reduced diameter portion to create either balanced or unbalanced operational characteristics, enabling mode conversion through relative positioning rather than requiring completely separate stem designs
2Reliability
If large actuators are used to operate surface safety valves, then the valve can function as a safety valve, but the actuators become large and expensive
Solution Approach 1:
The valve system dynamically adjusts its operational mode by axially moving and rotating the lower stem to align or misalign lugs with the reduced diameter portion of the valve member nut. This allows the valve to switch between balanced mode (reducing actuator size requirements) and unbalanced mode (enabling safety valve function), eliminating the need for permanently oversized actuators and reducing overall system complexity and cost while maintaining safety capabilities when needed
Data Source
AI summary
A system for converting operation of a valve between an unbalanced operation mode and a balanced operation mode includes a housing adapted to couple to a valve body. The system also includes a lower stem, including lugs, the lugs having a lug diameter that is larger than an adjacent lower stem diameter. The system further includes a valve member nut coupled to a valve member, the valve member nut having an opening to receive the lower stem, and pins extending into the opening, the pins forming a reduced diameter portion of the opening. In the system, the lower stem couples to the valve member, via the valve member nut, when the lugs are axially aligned with the reduced diameter portion and the lower stem decouples from the valve member when the lugs are axially misaligned with the reduced diameter portion.