GB2140846A

GB2140846A - Improvements in or relating to damping means

Info

Publication number: GB2140846A
Application number: GB08410657A
Authority: GB
Inventors: John Thomas Hird Webb
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-27
Filing date: 1984-04-26
Publication date: 1984-12-05
Also published as: GB8410657D0

Abstract

A drill string motion compensator comprises a cylinder body (44) and a piston (1) which is slidable in the cylinder body (44). A male drill rod end (12) is secured to the cylinder body (44) and a female drill rod end (38) is movable with the piston (1) and connected to the cylinder body (44) by a plurality of shock absorbers (28). In use, any excess longitudinal vibration is absorbed by relative movement of the male and female drill rod ends. The outer limit of motion of the female drill rod end is shown in dot-dash lines. <IMAGE>

Description

SPECIFICATION Improvements in or relating to damping means THIS INVENTION relates to improvements in or relating to damping means.

In one aspect, the invention provides damping apparatus for a drill string, comprising a drill rod having first and second portions which are movable relative to each other, for example, slidable relative to each other in the substantially longitudinal direction of the drill string, and means for damping the said movement.

The damping means of the present invention is also suitable for use with, for example, a pump string.

In a further aspect of the invention, a piston is slidable in a cylinder and each of the first and second portions is movable with a respective one of the piston and the cylinder. Preferably, the first portion is fixed to the cylinder and the second portion is connected to the cylinder by the damping means, which may comprise one or more shock absorbers, and movable with the piston.

For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side elevational view, partly in cross-section, of a drill string motion compensator in accordance with the invention, Figure 2 is a cross-sectional view taken along the line ll-ll of Fig. 1, Figure 3 is a view on the line X, partly taken in cross-section taken along the line Ill-Ill, of Fig. 1, and Figure 4 is a view on the line V of Fig. 3, with a part removed.

Referring now to the drawings, a drill string motion compensator comprises a cylinder body 44 and a piston 19 which is slidable in the cylinder body 44. A male drill rod end cover 14 is secured to one end of the cylinder body 44 by one or more capscrews 15 and a male drill rod end cover 14 by means of a retaining plate 13. Two "0" ring seals 9, 10 are provided between the male drill rod end cover 14 and the male drill rod end 1 2. The cylinder body 44 is provided with opposed cover plates 39, each of which is held in position by a plurality of capscrews 42, adjacent the male drill rod end cover 14.

An inner cylinder tube 18 is keyed to the male drill rod end cover 14 by means of a retainer 16 and one or more capscrews 1 7 which pass(es) through the retainer 16 and into the male drill rod end cover 14. An "O" ring seal 5 is provided between the male drill rod end cover 14 and the inner cylinder tube 18. Also, an inner piston 41 surrounds the inner cylinder tube 18 and is connected thereto by retainers 24, a piston retaining ring 20 and hexagonal headed bolts 40, and an "0" ring seal 6 is provided between the inner cylinder tube 18 and the inner piston 41.

The piston 19 is slidable between the cylinder body 44 and the inner piston 41. A bearing 27 and a seal 3 are provided between the inner piston 41 and the piston 19. The piston 1 9 is provided at the inner end thereof with bearings 23, 25 and a seal 1, which are secured in position between the piston 1 9 and the cylinder body 44 by means of a retainer 22 and a cushion sleeve 26, which are screwed to the piston 19 by a hexagonal headed bolt or bolts 21 and one or more capscrews 43, respectively, for movement with the piston 19. An "6" ring seal 8 is provided between the cushion sleeve 26 and the piston 19. The cushion sleeve 26 is arranged to seat against an inner shoulder of the cylinder body 44 at the outermost limit of the piston stroke.The cylinder body 44 is provided at the outer end thereof with a gland bearing 31 and a gland seal 2 which are secured to the cylinder body 44 by means of a gland plate 32 and a hexagonal headed bolt 33. An "O" seal 11 1 is provided between the cylinder body 44 and the gland plate 32, and a wiper seal 4 is provided between the gland plate 32 and the piston 19.

The outer end of the cylinder body 44 abuts a female drill rod end cover 35 which is fixed for movement longitudinally of the cylinder body 44 together with the piston 19, a female drill rod end 38 and four circumferentially spaced male arm members 46. The female drill rod end 38 is secured to the female drill rod end cover 35 by means of a retaining ring 37 and tab plate 36, and an "O" ring seal 7 is provided between the piston 19 and the female drill rod end 38.

The male arms members 46 are keyed to the female drill rod end cover 35 by means of an annular key 34 and are also fixed thereto by a plurality of capscrews 50, as can most clearly be seen in Figs. 3 and 4. Each male arm member 46 is connected at one end to a respective shock abosrber 28 which is mounted to the outer surface of the cylinder body 44 by means of a plurality of capscrews 29. Also, each male arm member 46 is arranged to slide in a female arm member 47, which is mounted to the outer surface of the cylinder body 44 by means of a plurality of capscrews 49 and which is provided with two recirculating roller bearings engaging lateral surfaces of the male arm member 47, as shown in Fig. 3. An arm top plate 48 engages each female arm member 47 so as to cover the respective male arm member 46.

In use, any excess longitudinal vibration of the drill motion compensator is absorbed by relative movement of the female drill rod end 38, together with the piston 19, and the male drill rod end 12, together with the cylinder body 44, which movement is damped by the shock absorbers 28. The outer limit of motion of the female drill rod end is shown in dotdash lines in Fig. 1.

Claims

1. Damping apparatus for a drill string or a pump string, comprising a drill rod or a pump rod having first and second portions which are movable relative to each other, and means for damping the said movement.

2. Damping apparatus according to Claim 1, wherein the first and second portions are movable relative to each other in the substantially longitudinal direction of the drill strings or pump string.

3. Damping apparatus according to Claim 1 or 2, wherein the first and second portions are slidable relative to each other.

4. Damping apparatus according to Claim 3, wherein a piston is slidable in a cylinder and each of the first and the second portions is movable with a respective one of the piston and the cylinder.

5. Damping apparatus according to Clam 4, wherein the first portion is fixed to the cylinder and the second portion is connected to the cylinder by the damping means and movable with the piston.

6. Damping apparatus according to any one of the preceding claims, wherein the damping means comprises one or more shock absorbers.

7. Damping apparatus for a drill string, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

8. Any novel feature or combination of features described herein.