BIT FOR DRILLING ON CASING STRING Russian patent published in 2022 - IPC E21B7/20 E21B10/42 E21B10/60 

FIELD: drilling of soil or rocks.

SUBSTANCE: invention relates to drilling equipment, in particular to devices for drilling wells made from drillable materials, and can be used for drilling on casing string. Drill bit for drilling on a casing string includes a body with flushing holes, cutting blades with PDC cutters for rock destruction, and calibrating blades. Calibrating blades are made integral with the housing with cutting blades with PDC cutters. Monolithic housing with calibrating and cutting blades with PDC cutters is made of drillable material, for example, cast iron, and is equipped with nipple thread. Housing is also provided with holes with plugs with shear screws. Diameter of PDC cutters makes 6–8 % of described bit diameter D. Minimum thickness of bit wall formed by central channel and outer surface of body thread is not less than 30 mm to exclude breakage during operation of device due to non-uniformity of drilled material.

EFFECT: proposed bit for drilling on casing string is simple design due to production of housing with cutting and calibrating blades of monolithic structure from drilled material, and also increased reliability during operation of the device due to increased thickness of the bit wall, elimination of jamming of assemblies during its drilling and elimination of additional costs during cementing of casing string.

1 cl, 1 dwg