DEVICE FOR STAGE CEMENTING OF CASING PIPE Russian patent published in 2010 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: device for stage cementing of casing pipe includes hollow housing with cementing holes and a plug in the wall, which is connected to upper and lower reducers; slide valve with cementing holes and split fixture, which is arranged on inner side of housing, sleeve with cementing and process holes and with a notch made on outer surface for interaction with fixture and arranged on inner side of slide valve and forming together with it, reducers and the housing the upper and lower process cavities, annular bushing installed in lower cavity and fixed on outer surface of the sleeve with a shear element, upper and lower bushings fixed on the sleeve with shear elements. On lower bushing there installed is differential bushing on shear elements and stop nut is fixed, which restricts movement of differential bushing relative to lower bushing in which there are holes covered with differential bushing; at that, those holes are interconnected with cementing holes in the sleeve, slide valve and housing.

EFFECT: improving operating reliability of the device and enlarging its application area especially in deep and in horizontal wells.

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