CASING STRING DRILLING DEVICE Russian patent published in 2021 - IPC E21B7/20 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the field of drilling oil and gas wells, and in particular to a device for drilling on a casing string. The device includes a casing string with a shoe equipped with windows located at the same level and evenly around the perimeter, a drilling tool adapter equipped with holes aligned in the working position with the shoe windows. The keys are inserted into the holes and windows with the possibility of movement inside, propped up in the working position from the inside by a plunger inserted into the adapter with the possibility of limited movement into the transport position and fixed relative to the adapter in the working position by shear elements. The inner diameter of the shoe is made less than the inner diameter of the casing, but larger than the outer diameter of the drilling tool. The shoe is equipped with a bushing made in the form of a centralizer and overlapping the shoe windows and movable keys made with the possibility of moving inwardly flush with the outer surface of the adapter and equipped with inclined dovetail grooves interacting with the corresponding inclined plunger grooves. In the lower part, the adapter is equipped with a seat for the ball, and in the upper part, with a threaded bushing that limits the upward movement of the plunger, and a hydraulic chamber communicated with the hole with the central channel of the plunger. The plunger in the upper part is equipped with a locking thread for connection with the fishing string with the possibility of transferring the plunger to the upper transport position when the fishing string is pulled.

EFFECT: exclusion of slime entering into device and device jamming in a horizontal well, as well as increase of reliability while removing the device from the well.

1 cl, 2 dwg