DEVICE FOR LOCAL ENLARGEMENT OF PROFILE AND CYLINDER PIPES IN WELL Russian patent published in 2011 - IPC E21B29/10 

FIELD: oil and gas production.

SUBSTANCE: device consists of case with central channel having threads for connection with downhole equipment and also having inclined slots. Supports with rolling elements are positioned in the channels and are designed to slide in them. The rolling elements are made in form of ball segments on axles set under angle to the axis of the case. The device further consists of a mechanism advancing the rolling elements into a working position. The mechanism corresponds to a circular sealed pusher travelling lengthwise and interacting with the case. The circular pusher is made as a circular cylinder mounted on the case and fixed from turning over. The circular cylinder and the case in its upper part form a hydraulic chamber communicated with the central channel of the case. On the case, in the hydraulic chamber of the cylinder wherein a circular internal groove is made, there is positioned a mechanism for holding the rolling elements in an idle position. This mechanism consists of segments of a hollow bush spring loaded outward and with cone surface on top. They interact with the circular groove of the cylinder. Also, above the segments there is positioned an additional circular piston equipped with an internal face interacting with cone surface of the segments when moving downward to take them out from the circular groove of the cylinder.

EFFECT: increased reliability and service life and reduced accident rate.

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