CASING STRING DRILLING TOOL JOINT ASSEMBLY Russian patent published in 2018 - IPC E21B7/20 E21B7/28 

FIELD: mining.

SUBSTANCE: invention relates to drilling of oil and gas wells, namely to methods of drilling on a casing string. Casing string drilling tool joint assembly includes a casing with a shoe inserted into the casing string of the drilling tool adapter, plunger with a top groove inserted into the adapter with the possibility of a limited movement of the downward movement in the transport position with the possibility of aligning the upper groove with the movable keys. Plunger with respect to the adapter and the shoe is fixed in the upper working position by shear elements. Inner diameter of the shoe is made smaller than the inner diameter of the casing, but larger than the outer diameter of the drilling tool. Shoe is equipped with windows located at the same level and evenly along the perimeter, and the adapter – holes, aligned in working position with the windows of the shoe. In the holes and windows are inserted with the ability to move inside the adapter due to the key stops, supported in the working position from inside the plunger. Adapter below the stop is equipped with grooves under the fishing tool, equipped with an extension designed to interact with the plunger and transfer it to the transport position. Dowels on the top and bottom are chamfered under the corresponding inclined surfaces of the shoe windows.

EFFECT: reliable fixation and retention of the drilling tool with the casing string during drilling, including with the help of the downhole motor, as well as guaranteed disengagement and extraction of the drilling equipment after the drilling is completed.

1 cl, 3 dwg