DEVICE FOR STEPWISE CEMENTING OF TAIL PIECE Russian patent published in 2009 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the field of construction and operation of oil and gas wells and, in particular, to devices for stepwise cementing of casing pipe tail pieces. Device comprises the casing pipe tail piece itself, transportation column connected to tail piece, stepwise cementing coupling installed in tail piece, upper and lower suspended hollow plugs installed on transportation column, interacting with internal surface of tail piece and having, every of them, body with windows, fitting seat-bush fixed in body by shear elements, external ring and inserts installed in body windows and fixing it in external ring, which in lower plug is connected to upper plug, and in upper plug - to tail piece. Plug bodies have possibility of their accordingly alternate unfixing relative to external rings in process of axial displacement of fitting seat-bushes into extreme bottom position, at that design travel of each of them exceeds height of inserts by 10-30%.

EFFECT: increase of device operation reliability as a whole, and also increase of suspended cementing plugs fixing reliability.

4 cl, 6 dwg