| 摘要 |
A drill string shut-off valve system for controlling the mud circulation system for deepwater marine drilling operations is disclosed, the drill string shut-off valve having a valve body having a cylinder, a main flow path, and a drilling mud flow channel, an upper and a lower connector on the valve body for installing the drill string shut-off valve into a drill string, and a valve positioned to selectively interrupt in the main flow path through the valve body or to complete the main flow path through the drilling mud flow channel. A piston in the cylinder is operably connected to the valve to drive it from an open to closed position. The piston has a first pressure face, a port presenting pressure from the upstream side of the valve to the first pressure face, anda second pressure face on the back of the piston. Exhaust ports present pressure from the annulus to the second pressure face and a spring biases the drill string shut-of valve to a closed position, but balanced with the area of the first pressure face to ensure valve opening at normal pump operation pressures. A spring adjustment assembly whereby the tension of the spring can be readily adjusted to allow for different drilling conditions is also disclosed.
|
