| 摘要 |
An explosive or combustion actuated subsurface well tool includes a firing head for initiating operation of the tool in response to a projectile, such as a ball or go-devil, being pumped down a tubing string extending from the surface. The firing head includes a passage sized to closely receive the ball or go-devil, in either a sealed manner in which substantially no liquid leaks around the pumped projectile or in an unsealed manner in which a small amount of liquid leaks around the projectile. As the projectile moves into the passage, the pressure drop across the projectile becomes quite large creating a large force sufficient to shear a safety pin, drive home a firing pin or otherwise initiating operation of the subsurface well tool.
|
