CHECK VALVE FOR CASING STRING Russian patent published in 2013 - IPC E21B34/06 

FIELD: oil and gas industry.

SUBSTANCE: device includes a housing, a mounting seat for interaction with a shutoff element in the form of a ball that is arranged in a cylindrical container, one end face of which is rigidly attached to the mounting seat, the other end face is provided with an axial channel and a mounting ball movement restrictor, and its side surface has holes and is closed with an elastic bushing on external surface. Length of cylindrical container is 1.5-3 of the ball diameter. A gap between outer diameter of cylindrical container and inner diameter of the housing in the arrangement place of the mounting seat, as well as elastic bushing, are chosen so that interaction of the latter with internal wall of the housing is provided during the process of well washing, pumping and cementing slurry squeezing to the space after the housing and casing string of the well at deformation of elastic bushing, which does not exceed maximum allowable value.

EFFECT: improving operating reliability of the valve; improving mounting reliability of a shutoff element on a mounting seat in working position of the device.

3 cl, 1 dwg