SLOT PERFORATOR Russian patent published in 2014 - IPC E21B43/112 

FIELD: mining.

SUBSTANCE: slot perforator for pipes comprises a body with power piston and puncher, barrel with a hollow plunger inside, connected with a stem entering the oil chamber. The cylinder is fitted with screw stopper and sub interconnected with each other by a calibrated shear tie. The sub is fitted with a bush with an internal ring lug. The hollow plunger is fitted with the extender installed inside a bush with forming of telescopic connection. The axial channel of the sub is hydraulically connected through holes with the axial channel of the cylinder. The axial channel of the hollow plunger is connected through circulating holes in its housing with bypass holes of the cylinder. The axial channel of the extender is connected by radial holes in its housing with the ring chamber between a bush and extender and is fitted with a seat with a ball valve connected to it through the shear tie. The bush is fitted with hydraulic channels designed with a possibility of connection of the ring chamber with the axial channel of the cylinder. The ring chamber under the hollow plunger is hydraulically connected through channels with annular space. The housing is fitted with a barrel with a restrictive lug, and the power piston is installed inside with a possibility of axial movement and interaction with the restrictive lug in a boundary position.

EFFECT: free lowering of the device into a well with crossflow of formation fluid from annular space inside the device and axial channel of a flexible pipe string, possibility of the termination of hydraulic connection of the axial channel of the flexible pipe string with annular space during perforation and possibility of returning of the power piston of punchers into transportation position.

3 dwg