Shock wave modification in percussion drilling apparatus and method

Patent metadata

Field	Value
Publication number	US-9637982-B2
Application number	US-201414917284-A
Country	US
Kind code	B2
Filing date	Aug 27, 2014
Priority date	Sep 9, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

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.

First claim

The invention claimed is:

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.

2. The apparatus claimed in claim 1 , wherein the ratio is in a range of 0.2 to 0.5.

3. The apparatus as claimed in claim 1 , wherein the ratio is in a range of 0.3 to 0.4.

4. The apparatus as claimed in claim 1 , wherein the ratio is in a range of 0.34 to 0.4.

5. The apparatus as claimed in claim 1 , wherein the sleeve length section is aligned coaxially with the length section of the adaptor between the rearward and forward ends.

6. The apparatus as claimed in claim 1 , wherein the annular wall includes an annular forward face positioned closest to the forward end and an annular rear face positioned closest to free end relative to the forward face.

7. The apparatus as claimed in claim 1 , wherein the adaptor is mounted at a rearward end of the drill string and axially between the drill string and the piston such that the energy transmission end of the piston is configured to strike directly the rearward end the adaptor.

8. The apparatus as claimed in claim 1 , wherein the adaptor is mounted axially within the drill string between a rearward end of the drill string and a drill tool mounted at a forward end of the drill string.

9. The apparatus as claimed in claim 1 , wherein a ratio between a cross sectional area of the sleeve and the energy transmission end of the piston in a plane perpendicular to a longitudinal axis of the piston and adaptor is in a range 0.3 to 1.5.

10. The apparatus as claimed in claim 9 , wherein the ratio of the cross sectional area is in a range of 0.7 to 1.3.

11. The apparatus as claimed in claim 1 , wherein the free end of the sleeve is positioned axially closer to the piston than the attachment end.

12. The apparatus as claimed in claim 1 , wherein the attachment end of the sleeve is positioned axially closer to the piston than the free end.

13. The apparatus as claimed in claim 1 , wherein the adaptor includes at least one male or female threaded end configured for coupling to a corresponding and respective female or male end of a drill rod forming part of the drill string.

14. A method of percussion drilling to affect at least one characteristic of a shock wave produced in a drill string, the method comprising:
creating a shock wave within a drill string by axially advancing an elongate piston having a main length and an energy transmission end, the energy transmission end contacting an intermediate adaptor;
transmitting the shock wave from the piston through the adaptor, the adaptor being an elongate energy transmission adaptor having a rearward end, a forward end and a length section positioned axially between the ends;
modifying at least one characteristic of the shock wave via 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 rearward and forward 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 of 0.1 to 1.0.

Assignees

• Sandvik Intellectual Property

Inventors

• Jansson Tomas Sh
• Rindeskar Andreas

Classifications

• E21B17/0426 Primary

  with a threaded cylindrical portion, e.g. for percussion rods · CPC title

• E21B1/02

  Surface drives for drop hammers {or percussion drilling}, e.g. with a cable · CPC title

• E21B1/00

  Percussion drilling · CPC title

• E21B1/24

  the impulse member being a piston driven directly by fluid pressure · CPC title