COLLAR FOR STAGE CEMENTING OF CASING STRING IN A WELL Russian patent published in 2021 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, in particular to the field of construction of oil and gas wells, namely to devices for staged cementing of the casing in two stages. The collar for staged cementing of the casing in the well includes a hollow body with an internal shoulder and connecting threads at the ends. A sub is attached to the upper thread, the cementing holes are closed with destructible elements, the sealing rings are installed above the cementing holes. The locking flap is installed inside the body above the cementing holes and is equipped with a lock in the form of a split spring ring. The drillable landing seat is installed inside the locking flap, secured by a shear pin to the ring installed at the junction between the body and its sub. The body is made thickened, with longitudinal grooves made on its outer surface. The cementing holes are made between the longitudinal slots and are equipped with spring-loaded valves that open from the inner side of the body. The valve seat body is installed hermetically and on the outside is provided with a support platform for the valve spring with holes for the passage of the cement slurry. The destructible elements covering the cementing holes are made in the form of shear nozzles installed on the inner side of the body. Shear-off nozzles are closed with a stopper and rigidly fixed to the valve seat body or made integral with the valve seat body. In the upper part of the locking flap, an internal groove is made, which forms a ledge with the possibility of placing a drillable landing saddle with a counter protrusion under the ledge of the locking valve.

EFFECT: increased reliability by ensuring high tightness of the closure of the cementing holes on both sides - a flap and a valve.

1 cl, 6 dwg