DEVICE FOR WELLHEAD SEALING Russian patent published in 2003 - IPC

FIELD: well drilling and operation. SUBSTANCE: device for wellhead sealing includes body, cover and sealing includes body, cover and sealing member. Piston has plunger projection and surface for sealing member. There are working and return chambers. Hydraulic channels communicate working and return chambers with a source of hydraulic pressure. Piston has cylindrical external and internal extensions. Sealing collars of separator are distributed over surfaces of different diameters and made M-shaped. Piston moves upward with pressure supply to compress sealing member which moves into body hole and embraces tool or closes free wellhead space. Axial force from piston and from wellhead pressure is transmitted through sealing member to cover. When piston moves, motion limiters move sleeve. In depressurization, pressure is supplied to return chamber and piston lowers. Sealing member frees tool. Possibility occurs to seal wellhead with high working pressure characteristic for universal preventers with provision of tool forward motion by device which is considerably lower in dimensions and weight. EFFECT: higher efficiency of use. 4 cl, 2 dwg