DRILL PIPE STRING AND ASSEMBLY ROD REDUCTION OF DRILL PIPE STRING TORQUE Russian patent published in 1998 - IPC

FIELD: well drilling, in particular, equipment for reduction of torque of drill pipe string in the course of drilling. SUBSTANCE: assembly has hollow mandrel elongated in longitudinal direction which may be connected between adjacent first and second drill pipes of string and bushing freely rotating round mandrel and having outer diameter exceeding the diameter of any connecting component of the first or second drill pipe. Displacement of bushing in longitudinal direction with respect to mandrel is prevented with the help of means installed inside bushing. Assembly allows reduction of consumption of energy resources due to reduction of torque of drill pipe string by reduction of losses for friction between drilled well and rotating components in drill pipe string. EFFECT: higher efficiency. 17 cl, 18 dwg