초록 ▼

A method is disclosed for controlling the mud circulation system for deepwater marine drilling operations in which a drill string is run from surface facilities, through a blowout preventor and into a borehole. Mud is injected into the drill string, up a borehole and through the blowout preventor ad

A method is disclosed for controlling the mud circulation system for deepwater marine drilling operations in which a drill string is run from surface facilities, through a blowout preventor and into a borehole. Mud is injected into the drill string, up a borehole and through the blowout preventor adjacent the sea floor. There the mud is withdrawn from a mud exit return line near the blowout preventor and the hydrostatic head from the mud in the drill string is isolated from the relatively lesser ambient pressure at the sea floor seen at the mud exit return line with a pressure activated drill string shut-off valve when mud circulation is interrupted. A drill string shut-off valve system for controlling the mud circulation system for deepwater marine drilling operations is also disclosed. Further, a method of well control to overcome formation pressure in a well control event is disclosed.

대표청구항 ▼

[ What is claimed is:] [1.]1. A drill string shut-off valve system for controlling a mud circulation system for deepwater marine drilling operations, comprising:a drill string run from the surface, through a blowout preventor and down a wellbore;mud in the drill string, the wellbore and the blowout

[ What is claimed is:] [1.]1. A drill string shut-off valve system for controlling a mud circulation system for deepwater marine drilling operations, comprising:a drill string run from the surface, through a blowout preventor and down a wellbore;mud in the drill string, the wellbore and the blowout preventor;a mud exit return line above the blowout preventor, near the sea floor; anda bottom hole assembly at the end of the drill string, the bottom hole assembly comprising:a drill bit; anda bottom hole assembly drill string shut-off valve suitable to selectively isolate the hydrostatic head of the mud in the drill string from ambient hydrostatic pressure of seawater at the mud exit return line when mud circulation is interrupted.