SLEEVE FOR MULTISTAGE CEMENTING OF WELLS Russian patent published in 2001 - IPC

FIELD: casing of oil and gas wells, particularly, multistage cementing of wells. SUBSTANCE: well multistage cementing sleeve has body with central and radial channels. Installed on the outside of body for axial displacement is stepped sliding bushing with radial holes and members of its fixing. Body accommodates a container. It has radial holes, seat, circular seals and shear members. There are overlapping and separating plugs in the body. Rigidly secured to body are upper and lower protective bushings. Said bushings together with body form upper and lower circular chambers which are filled with incompressible liquid. Body has additional radial channels. Accommodated in channels are movable plugs and springs. Container has external annular grooves. Bushing has radial holes in which bushings and plugs are located. Sliding bushing is stepped in its upper and lower parts. EFFECT: higher operating reliability. 3 cl, 7 dwg