WELL CONSTRICTOR Russian patent published in 2001 - IPC

FIELD: oil and gas industry, well equipment of oil and gas fields. SUBSTANCE: well constrictor provides for increased gas capacity from upper formations above packer in circuit of well production over single tubing string, prevents overflow of gas from lower under-packer to upper above-packer formations if well is shut down without plugging, prevents overflow of gas into tubing string while repair operations are carried out in well when pressure in space opposite to well constrictor is higher than pressure in tubing string. Well constrictor is put on tubing string and has carcass with holes, spring-loaded non-return valve and separable extension piece. Carcass has connection thread on top and bottom which is used for direct joining to tubing string. Carcass is provided with enclosure. Non-return valve and extension piece are positioned in circular clearance between carcass and enclosure. Sleeve with holes is mounted for its displacement by tool of cable mechanism to match or mismatch holes in sleeve and carcass and is located inside carcass. EFFECT: enhanced functional reliability and efficiency. 1 dwg, 1 tbl