Method and apparatus for reducing drill bit wear

摘要

A turbine for driving a drill bit includes means for locking the turbine rotor. A generally cylindrical locking assembly is connected to the rotor via a splined connection which permits relative axial movement of the locking assembly and rotor while restricting relative rotational movement thereof. A tab extends radially outwardly from the locking assembly and is receivable in an axial groove formed on the inner surface of the turbine case. When so received, rotational movement of the locking assembly and thus the rotor is prevented. An annular cavity is formed on the inner surface of the turbine case adjacent one end of the groove. When the tab is received therein, rotational movement of the locking assembly and rotor relative to the turbine case is permitted. A wellbore may be reamed and washed with the rotor in its locked condition by rotating the drill string as in conventional rotary drilling and circulating fluid.