CASING DRILLING DEVICE WITH RETRIEVABLE DRILLING ASSEMBLY Russian patent published in 2023 - IPC E21B7/20 

FIELD: oil and gas industry.

SUBSTANCE: drilling of oil and gas wells with simultaneous isolation of areas of shedding and collapse when drilling with a casing string. A device for drilling on a casing with a retrievable drilling assembly includes a casing string made of casing pipes connected to each other by couplings, with a connecting device at the end, and a retrievable drilling assembly containing a downhole motor and a bit and connected to the connecting device by an adapter. The connecting device body on the outer surface in the lower part is equipped with grooves with blades with PDC cutters mounted rigidly in the grooves in such a way that the end part of the blades is located below the end part of the connecting device body with the possibility of drilling a wellbore with a diameter sufficient for running the sleeve casing. The inner surface of the blades is made to match the internal lead-in chamfer of the connecting device body. The adapter of the connecting device is equipped with flushing holes, and the blades are made unified for connecting devices for drilling different standard sizes of casing strings.

EFFECT: proposed device for drilling on a casing string with a retrievable drilling assembly is easy to manufacture due to the unification of the blades for different standard sizes of casing strings, is reliable in operation, and eliminates the abandonment of rock-cutting tools at the bottom of the well.

1 cl, 2 dwg