DEVICE FOR SEALING OF WELL MOUTH

FIELD: oil and gas production industry. SUBSTANCE: this can be used in construction and overhaul of oil and gas wells. Device incorporates body with central axial stepped passage and radial passages. Located in body are ball-shaped locking members with seats, turning units in the form of shaped sleeves, and with detention units. Installed in stepped radial passage is controllable valve made in the form of plug with axial passages and splined joint made in its external end. Radial passage is made between locking members, and installed in this passage is removable stopper. Valve is operated by means of key which has base with central axial stepped passage which accommodates hollow rod, sealing collar and main bush. Located externally of hollow rod is pressing bush. Made in one end of hollow rod is spline intended for operation of valve. This spline is mating to splined joint in plug. Made in other end of hollow rod is socket with internal thread for pressure gauge. Installed on outside of base is coupling nut. By means of this coupling nut it is possible to effect sealing of hollow rod relative to base. In case of danger of occurring gas-, oil-, water-appearance, device is installed on well mouth and is connected to drilling or production string. Pipe hollow of well is closed by means of one of two available locking members. Other locking member remains in reserve. Value of surplus pressure in pipe passage of well is determined by connecting valve operating key with radial passage which is opened by turning hollow rod together with plug. Value of surplus pressure in well hollow passage is read by indications of pressure gauge which is installed on hollow rod. In case of necessity, it is possible to deliver weighted flushing solution into pipe passage of well through radial passage when one of ball-shape locking member is closed and other ball-shaped locking member is open. Application of aforesaid embodiment of device improves operating efficiency, allows for quick determining of value of surplus pressure in well p