The function of double-wall annular check valve

The double-wall annular check valve is a special valve installed in double-wall drilling tools, primarily used to prevent the backflow of circulating fluid and cuttings into the annular gap between the inner and outer pipes of the double-wall drilling tools during drilling pauses. Here are the main functions of the double-wall annular check valve:

1. **Prevent Backflow**:

   - During drilling, when the drill pipe stops rotating, the valve prevents the drilling fluid and cuttings from flowing back from the bottom of the well into the drill pipe interior, thus maintaining cleanliness and pressure balance inside the drill pipe.

2. **Maintain Circulation System Stability**:

   - By preventing backflow, the double-wall annular check valve helps maintain the stable operation of the drilling fluid circulation system, avoiding pressure fluctuations in the circulation system caused by backflow.

3. **Protect Drilling Tools**:

   - Preventing cuttings and mud from entering the interior of the drilling tools reduces wear and damage to the tools, extending their service life.

4. **Improve Drilling Efficiency**:

   - Ensuring the unidirectional flow of drilling fluid, the double-wall annular check valve helps improve drilling efficiency, reducing drilling interruptions and additional cleaning work caused by backflow.

5. **Enhance Safety**:

   - In drilling operations, preventing the backflow of drilling fluid and cuttings can reduce the risk of blowouts and other safety accidents, enhancing the overall safety of the drilling process.

The design and application of the double-wall annular check valve are of great significance for ensuring the smooth progress of drilling operations and the safe operation of equipment.