Shock wave modification in percussion drilling apparatus and method

摘要

A percussion drilling apparatus is arranged to affect at least one characteristic of a shock wave produced in a drill string. The apparatus includes an elongate energy transmission adaptor having a shock wave modification sleeve configured with a free end and an attachment end projecting radially from an outer surface of the adaptor.

主权项

1. A percussion drilling apparatus arranged to affect at least one characteristic of a shock wave produced in a drill string, the apparatus comprising:
an elongate piston having a main length and an energy transmission end, the piston being mounted to shuttle back and forth axially to create a shock wave within the drill string; an elongate energy transmission adaptor having a rearward end in contact with the energy transmission end to receive energy from the piston, a forward end for coupling to the drill string, and a length section positioned axially between the ends, wherein the adaptor includes an elongate shock wave modification sleeve having a free end and an attachment end formed as an annular wall that projects radially from the length section of the adaptor at an axial position between the ends such that a main length section and the free end of the sleeve are separated radially from and surround a region of an outer surface of the length section of the adaptor; and an annular gap region positioned radially between the outer surface and the main length section, wherein a ratio of an axial length of the sleeve main length section and an axial length of the main length of the piston is in a range 0.1 to 1.0.