When overflow occurs during the drilling process and the water hole of the drill bit is blocked and cannot kill the well, if a bypass valve is connected to the drill string, we can throw the ball to break the pressure and cut off the shear pin. At this time, the valve seat moves down and the drain hole is opened to form a new circulation channel.

The bypass valve is installed between the drill collar and the drill pipe or 30 ~ 50m away from the check valve of the drilling tool. The bypass valves of horizontal wells and highly deviated wells are installed in the drilling tools of 500 ~ 700 well sections.