FIELD: oil and gas production, particular, devices for piercing perforators providing formation of channels in string and drill string-borehole annulus. SUBSTANCE: device for piercing of casing string of oil-gas wells has body accommodating hydraulic piston and piercing unit connected with it. Piercing unit is assembled of separate transverse plates. They are installed on rod which is connected with hydraulic piston. Plates form conical figure whose generator is in form of straight, broke or irregularly shaped lines and taper angle exceeding friction angle on steel. EFFECT: higher efficiency. 3 cl, 13 dwg
