Overview and Working Principle of Dual-Wall Circulation Dual-Passage Single-Seal Plug Valve for Petroleum Drilling Overview and Working Principle of Dual-Wall Circulation Dual-Passage Single-Seal Plug Valve for Petroleum Drilling

Overview  

The dual-wall dual-passage single-seal plug valve is a manually operated plug valve designed for reverse circulation drilling operations and connected to dual-wall drill pipes. Its structure features two isolated flow paths:  

- The annulus between the valve body and the inner central tube serves as the gas or liquid passage.  

- The inner central tube provides a separate liquid or gas passage, with the two channels being hermetically sealed and isolated from each other.  

Working Principle  

1. Normal State (Open Position)  

   - The valve is normally open during standard drilling operations, allowing simultaneous flow through both channels (annulus and inner tube).  

2. Emergency Closure (During Overflow or Kick)  

   - When an overflow or kick occurs (uncontrolled influx of formation fluids), the valve can be quickly closed by rotating the ball 90° using a specialized wrench. This action:  

     - Blocks upward flow of formation fluids through the drill string’s inner bore.  

     - Maintains isolation between the dual channels to prevent cross-contamination.  

3. Key Functions  

   - Dual-Passage Flow Control: Enables independent or combined use of the annulus and inner tube for fluid/gas circulation.  

   - Single-Seal Inner Bore Shutoff: Seals the inner tube while maintaining annulus integrity, critical for emergency well control.  

   - Synchronized Operation: When paired with a downhole dual-wall annular check valve, it ensures simultaneous opening or closing of both channels, enhancing operational flexibility and safety during complex drilling scenarios.  

Applications in Drilling Operations  

- Reverse Circulation Drilling: Efficiently transports cuttings to the surface via the annulus while injecting clean fluid through the inner tube.  

- Well Control: Rapid response to kicks or blowouts by isolating the inner bore, buying time to activate primary barriers (e.g., BOPs).  

- Multi-Fluid Management: Supports simultaneous injection of different fluids (e.g., drilling mud, gas, or foam) through separate channels.  

Advantages  

- Emergency Response: Manual override enables immediate action during power or system failures.  

- Dual-Channel Flexibility: Optimizes fluid management for complex drilling conditions.  

- Robust Isolation: Prevents intermixing of fluids/gases, critical for wellbore stability.  

- Compatibility: Integrates seamlessly with dual-wall drill pipes and downhole check valves. 

Summary  

The dual-wall dual-passage single-seal plug valve is a critical component in advanced drilling systems, enabling precise control over dual fluid/gas channels while providing rapid emergency shutoff. Its design ensures safe and efficient reverse circulation operations, making it indispensable for managing high-risk scenarios like kicks or blowouts in petroleum drilling.