DEVICE FOR DRILLING ON CASING STRING WITH RECOVERABLE DRILLING ASSEMBLY Russian patent published in 2024 - IPC E21B7/20 E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry and can be used for drilling and cementing in open and cased borehole. Disclosed is a device for drilling on a casing string with a recoverable drilling assembly, comprising a coupling with an expansion cone and a thread for attaching the device to a transportation pipe string, housing, made in the form of an expandable branch pipe equipped with a narrowing, a shank, a drilling assembly, which includes a bit, screw downhole motor, reamer and connecting device for connection of drilling assembly with shank bottom, sub connecting branch pipe and shank, uncoupling device consisting of grooves made on coupling and expanding cone arranged in expandable branch pipe with possibility of coupling pushing out of branch pipe due to its expansion by its coupling cone. At the same time the coupling in the lower part is equipped with ledges for the sub slots providing its synchronous rotation with the shank during drilling, with a cylindrical recess and a radial hole connecting the central channel of the coupling with the cylindrical recess. Expandable branch pipe on the outer surface at the point of narrowing is equipped with rigidly fixed dies with a toothed surface on the outside with the possibility of fixation in the inner part of the previous casing string during expansion of the expandable branch pipe with dies. On top of the coupling there is a piston with a hydraulic chamber connected to the upper part of the expandable branch pipe with the possibility of disconnection and a radial hole below the piston, which is covered by a seat with a shear element for a releasable ball. Radial hole of the lower part of the coupling, which connects the central channel of the coupling with the cylindrical recess, is covered with a bushing. Inner surface of the sub has a length and a diameter for a cylindrical branch pipe with a suspended cementing plug, which is installed in the sub during cementing.

EFFECT: providing reliable fixation of the shank relative to the previous casing string during extraction of the drilling assembly and guaranteed detachment of the drill string from the device and cementing the shank along the entire length.

1 cl, 3 dwg