Percussion tool for generic downhole fluid motors

Apparatus for drilling earthen boreholes with a non-rotating, fluid conducting drill string, comprising:

• a fluid powered rotary motor mounted on the downhole end of the drill string to receive fluid for rotation;
• a fluid powered, axially reciprocating hammer having a central shaft;
• a tubular housing connected with the drill string;
• a reciprocating annular piston mass slip fitted to operate inside of the tubular and on the central shaft;
• a rotary coupling with freedom for axial movement connecting the upper end of the central shaft to the downhole end of the motor with the coupling, so that the central shaft will be rotated by the motor but axially isolated therefrom;
• at least one port to conduct fluid from the drilling string to the upward end of the piston, for moving the piston downwardly;
• at least one port to conduct fluid from the drilling string to the downward end of the piston, for moving the piston upwardly;
• a drill bit rigidly connected to the downhole end of the central shaft;
• and
• a fluid passageway supplying fluid from the drill string to the drill bit.

An improved apparatus for drilling earthen boreholes with a fluid powered rotary motor mounted on the downhole end of a non-rotating, fluid conducting drill string, wherein the improvement comprises:

• a fluid powered, axially reciprocating hammer having a central shaft;
• a tubular housing connected with the drill string;
• a reciprocating annular piston slip fitted to operate inside of the tubular and on the central shaft;
• a rotary coupling with freedom for axial movement connecting the upper end of the central shaft to the downhole end of the motor with the coupling, so that the central shaft will be rotated by the motor and yet axially isolated therefrom;
• at least one port to conduct fluid from the drilling string to the upward end of the piston, for moving the piston downwardly;
• at least one port to conduct fluid from the drilling string to the downward end of the piston, for moving the piston upwardly;
• a drill bit rigidly connected to the downhole end of the central shaft;
• and
• a fluid passageway supplying fluid from the drill string to the drill bit.

An improved method for drilling earthen boreholes with a fluid powered rotary motor mounted on the downhole end of a non-rotating, fluid conducting drill string, wherein the improvement comprises the steps of:

• providing a fluid powered, axially reciprocating hammer;
• providing a rotary coupling with freedom for axial movement
• connecting the reciprocating hammer to the downhole end of the motor with the coupling, so that the hammer will be rotated by the motor and the motor will be axially isolated from the hammer;
• connecting a drill bit in rigid assembly with the downhole end of the reciprocating hammer so that the action of the drill bit will be both rotating and axially reciprocating,
• supplying fluid through the drill string;
• rotating the motor with fluid supplied through the drill string;
• and
• reciprocating the hammer with fluid discharged from the motor.