U.S. patent application number 13/382753 was filed with the patent office on 2012-11-01 for core barrel and related drilling apparatus and method.
Invention is credited to Ludovic Delmar, Eric Fannes, Olivier Mageren.
Application Number | 20120273279 13/382753 |
Document ID | / |
Family ID | 43429601 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120273279 |
Kind Code |
A1 |
Delmar; Ludovic ; et
al. |
November 1, 2012 |
Core Barrel and Related Drilling Apparatus and Method
Abstract
There is disclosed herein drilling apparatus, in particular for
use in the field of oil prospecting, comprising: a first tubular
member (1, 2, 3); a second tubular member (6, 7, 8, 9) mounted at
least partly within the first tubular member so as to be
reciprocally free in rotation with respect to the first tubular
member about an axis (5); and a drill bit (4) operatively connected
to one of the first or second tubular members so as to be rotated
in response to the one tubular member being turned in order to
effect drilling, characterised in that: the drilling apparatus
further comprises a restoring member (18, 36) for applying a forces
between the first tubular member and the second tubular member at
least in respective first axial directions in response to relative
displacement of the first tubular member and the second tubular
member in the respective opposite axial directions. Also provided
are a tubular assembly and a method of assembling tubular
members.
Inventors: |
Delmar; Ludovic; (Braine
l'alleud, BE) ; Mageren; Olivier; (Jette, BE)
; Fannes; Eric; (Braine-l'Alleud, BE) |
Family ID: |
43429601 |
Appl. No.: |
13/382753 |
Filed: |
July 8, 2010 |
PCT Filed: |
July 8, 2010 |
PCT NO: |
PCT/EP2010/059845 |
371 Date: |
July 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61223940 |
Jul 8, 2009 |
|
|
|
Current U.S.
Class: |
175/367 ;
175/327; 175/403; 29/456 |
Current CPC
Class: |
E21B 17/043 20130101;
E21B 25/16 20130101; Y10T 29/49881 20150115; E21B 10/02 20130101;
E21B 17/18 20130101; E21B 25/00 20130101; E21B 17/042 20130101;
E21B 19/16 20130101 |
Class at
Publication: |
175/367 ; 29/456;
175/327; 175/403 |
International
Class: |
E21B 10/22 20060101
E21B010/22; E21B 10/00 20060101 E21B010/00; E21B 10/06 20060101
E21B010/06; E21B 19/16 20060101 E21B019/16 |
Claims
1-19. (canceled)
20. A drilling apparatus for oil prospecting, comprising: a first
tubular member; a second tubular member mounted at least partly
within the first tubular member so as to be reciprocally free in
rotation about an axis with respect to the first tubular member; a
drill bit operably connected to one of the first or second tubular
members so as to be rotated in response to the one tubular member
being turned in order to effect drilling; and a spring member for
applying a force between the first tubular member and the second
tubular member at least in a respective first axial direction in
response to relative displacement of the first tubular member and
the second tubular member in respective opposite axial
directions.
21. The drilling apparatus of claim 20, further comprising: an
outer assembly formed by the first tubular member and the drill
bit, wherein the first tubular member includes at least one outer
tube and the drill bit is a core bit; an inner assembly formed by
the second tubular member and at least one core removal element,
wherein the second tubular member includes at least one inner tube;
a holder configured to hold the inner assembly in the outer
assembly, the holder including at least one rolling bearing
arranged between the inner assembly and the outer assembly so that
the inner and outer assemblies are reciprocally free in rotation;
and at least one spacer element formed in part by the spring
member, wherein the spacer element is housed inside the outer
assembly such that the spacer element bears against a bearing
surface of one of the inner and outer assemblies and the rolling
bearing to axially bias the rolling bearing away from the bearing
surface.
22. The drilling apparatus of claim 20, wherein the spacer element
further comprises: an upstream tubular part that bears against the
at least one outer tube; a downstream tubular part that bears
against the rolling bearing, wherein the spring member is arranged
between the upstream and downstream tubular parts and bears against
the upstream and downstream tubular parts to act axially thereon so
as to move apart the upstream and downstream tubular parts; and
retaining features configured to limit the moving-apart of the
upstream and downstream tubular parts.
23. The drilling apparatus of claim 22, wherein the spring member
comprises spring washers.
24. The drilling apparatus of claim 22, wherein: one of the
upstream and downstream tubular parts includes a female tubular end
piece and the other tubular part includes a male tubular end piece
configured to slide axially inside a cavity of the female tubular
end piece; and the spring member is housed at a bottom of the
cavity such that the spring member bears against the male end piece
pushed into the female end piece.
25. The drilling apparatus of claim 24, wherein the retaining
features comprise: a plurality of elongate slots extending in the
axial direction in the female tubular end piece; and locking
elements coupled to the male tubular end piece so as to protrude
radially into the elongate slots and to limit a spacing of the
upstream and downstream tubular parts by bearing against one end of
the elongate slots.
26. The drilling apparatus of claim 21, wherein the holder further
comprises an upstream rolling bearing and a downstream rolling
bearing placed around one of the inner tubes and housed inside one
of the outer tubes, the downstream rolling bearing being arranged
between a downstream-facing first annular bearing surface of the
one inner tube and an upstream-facing annular stop surface of the
one outer tube, the upstream rolling bearing being arranged between
an upstream-facing second annular bearing surface of the one inner
tube and the spacer element, the first and second annular bearing
surfaces of the one inner tube being located between the upstream
and downstream rolling bearings.
27. The drilling apparatus of claim 26, wherein: the first and
second annular bearing surfaces of the one inner tube are provided
on an annular flange that protrudes radially therefrom and is
clamped between the upstream and downstream rolling bearings; the
upstream rolling bearing is axially spaced apart from the outer
assembly by the spring member of the spacer element; and the
downstream rolling bearing is retained by the annular stop surface
of the one outer tube.
28. The drilling apparatus of claim 26, wherein: the one outer tube
comprises an upstream section and a downstream section screwed to
one another; the spacer element bears between the upstream section
and the upstream rolling bearing; and the downstream section
includes the annular stop surface on which the downstream rolling
bearing bears, the screwing of the upstream section and the
downstream section being adjustable to adjust an prestressed spring
force of the spring member of the spacer element.
29. The drilling apparatus of claim 26, further comprising an
additional spacer element inserted between the downstream rolling
bearing and the upstream-facing annular stop surface of the one
outer tube.
30. The drilling apparatus of claim 29, wherein the additional
spacer element is a spring member.
31. The drilling apparatus of claim 26, wherein: the one inner tube
of the inner assembly is held by the holder at an upstream end; and
the one inner tube includes an outer thread at a downstream end
configured to cooperate with an inner thread of another inner tube
of the inner assembly in order to fix the inner assembly in an
axially adjusted condition.
32. The drilling apparatus of claim 31, further comprising a
threaded locking nut arranged on the outer thread of the downstream
end of the one inner tube, wherein the locking nut is clamped
against the another inner tube when the inner assembly is in said
axially adjusted condition.
33. The drilling apparatus of claim 31, further comprising a
locking washer clamped around the threaded downstream end of the
one inner tube when the inner assembly is in the axially adjusted
condition and located between a threaded locking nut and the
another inner tube, wherein the locking washer is arranged to
prevent any unscrewing of the locking nut and of the another inner
tube on the threaded downstream end.
34. The drilling apparatus of claim 20, wherein the drilling
apparatus is a core barrel.
35. A tubular assembly for oil prospecting, comprising: a first
tubular member; a second tubular member threaded part way onto a
threaded portion of the first tubular member, the second tubular
member configured to be threaded further onto or partially
unthreaded from the first tubular member to adjust the assembled
length of the first and second tubular members; and a locking nut
configured to be moved to a locking position to prevent the second
tubular member being further threaded onto or unthreaded from the
first tubular member.
36. The tubular assembly of claim 35, further comprising: a locking
washer including, respectively, corresponding notches or
projections thereon to engage with projections or recesses on the
second tubular member and the locking nut when the locking nut is
moved to the locking position to prevent relative rotation between
the second tubular member, the locking washer and the locking
nut.
37. The tubular assembly of claim 36, wherein: the first tubular
member includes recesses that extend along at least a portion of
the length thereof; and the locking washer includes inner
projections to engage in the recesses when the locking nut is moved
to the locking position to prevent relative rotation between the
locking washer and the first tubular member.
38. A method of assembling tubular members for oil prospecting,
comprising: threading a first tubular member part way onto a
threaded portion of a second tubular member to obtain a desired
assembled length of the first and second tubular members; and
moving a locking nut into a locking position to prevent the first
tubular member from being further threaded onto or unthreaded from
the second tubular member.
39. The method of claim 38, further comprising providing a locking
washer, and wherein moving the locking nut to the locking position
prevents further relative rotation between the first tubular
member, the locking washer and the locking nut and/or between the
locking washer and the second tubular member.
Description
[0001] The present invention relates to drilling apparatus. The
invention may find particular application in a core barrel, in
particular for use in the field of oil prospecting, comprising
[0002] at least one outer tube and a core bit which form an outer
assembly, [0003] at least one inner tube and core removal elements
which form an inner assembly, and [0004] a holder for holding the
inner assembly in the outer assembly which comprise at least one
rolling bearing arranged between them so that these assemblies are
reciprocally free in rotation.
[0005] In a customary core barrel, the outer assembly is driven in
rotation and the core bit can therefore dig a core hole. During
this time, the inner assembly is held inside the outer assembly in
a position fixed in terms of rotation, while being driven axially
by the outer assembly.
[0006] Core barrels may be made to pass through geological layers,
thereby generating very high levels of vibration in the core
drilling equipment. Often, the tools that exist on the market do
not withstand these extreme conditions. This is because the axial
vibrations increase the risks of jamming of the system for holding
the inner assembly inside the outer assembly. They may also cause
damage to the numerous threads which are usually used to join
together the outer assembly and inner assembly. Finally, these
axial vibrations often have the effect of modifying the axial
position of the inner assembly relative to the outer assembly
whereas, in order for the core to be removed correctly, it is
desirable that the respective depth positions of the core bit and
of the core removal elements are appropriately adjusted.
[0007] It would be desirable to develop a core barrel in which
these above-described vibrations which damage the threads are
greatly reduced. It would also be desirable to considerably
simplify the core drilling equipment and to reduce as far as
possible the number of threads and also the number of parts.
Finally, it would also be desirable to lock the system for
adjusting the axial position of the inner assembly in the outer
assembly, so as to prevent any disconnection between these once
this position has been adjusted.
[0008] The present invention has been made in view of the foregoing
background. A drilling apparatus according to a first aspect of the
present invention is defined in claim 1 below.
[0009] In one embodiment, the drilling apparatus is realised as a
core barrel as indicated in the introduction, and which further
comprises at least one spacer element which is housed inside the
outer assembly, bearing on the one hand against a bearing surface
of one of said inner and outer assemblies and on the other hand
against the rolling bearing, the restoring member being a spring
member that axially biases said rolling bearing away from the
bearing surface.
[0010] The spring member, which is preferably prestressed, has the
effect, when axial vibrations of the inner assembly occur, of
absorbing these vibrations and therefore filtering them.
[0011] According to one embodiment of the invention, the spacer
element comprises an upstream tubular part which bears against an
aforementioned outer tube, and a downstream tubular part which
bears against an aforementioned rolling bearing, said spring member
being arranged between these upstream and downstream tubular parts,
bearing against each of them and acting thereon axially so as to
move them apart, the spacer element additionally comprising
retaining features which limit the moving-apart thereof.
[0012] The terms upstream and downstream in the context of the
present invention are to be understood as a function of the core
drilling direction, an upstream position or element being closer to
the surface and a downstream position or element being closer to
the bottom of the core hole. The spring member advantageously
consists of spring washers. The latter are preferably arranged so
that all the spring washers exert an elastic stress both in the
upstream direction and in the downstream direction. Other known
spring member can of course be envisaged, for example a helical
spring.
[0013] According to one advantageous embodiment of the invention,
one of said upstream and downstream tubular parts has a female
tubular end piece and the other has a male tubular end piece
capable of sliding axially inside a cavity of the female tubular
end piece, and the spring member is housed at the bottom of said
cavity, bearing against the male end piece pushed into the female
end piece. The spacer element is in this way in an advantageously
compact form.
[0014] Said retaining features, which limit the moving-apart
described above, advantageously comprise a plurality of elongate
slots provided in the axial direction in the female tubular end
piece and locking elements fixed to the male tubular end piece so
as to protrude radially into said elongate slots and to lock a
predetermined spacing of said tubular parts by bearing against one
end of said elongate slots. This arrangement allows a particularly
simple and robust installation of the spacer element.
[0015] According to one particularly advantageous embodiment of the
invention, said holder comprises two upstream and downstream
rolling bearings placed around an aforementioned inner tube and
housed inside an aforementioned outer tube, the downstream rolling
bearing being arranged between a downstream-facing first annular
bearing surface of the inner tube and an upstream-facing annular
stop surface of the outer tube, whereas the upstream rolling
bearing is arranged between an upstream-facing second annular
bearing surface of the inner tube and said spacer element, said
first and second annular bearing surfaces of the inner tube being
located between the two rolling bearings.
[0016] The particular arrangement of an inner tube biased axially
in the downstream direction by a spring member and clamped between
two rolling bearings makes it possible to eliminate almost all the
threads which, in the prior art, were necessary to ensure the
connection between the outer assembly and inner assembly. This
results in an item of equipment which is particularly robust and
resistant to vibrations. The inner tube remains in a very stable
position, correctly aligned axially by the two rolling
bearings.
[0017] Advantageously, said first and second annular bearing
surfaces of the aforementioned inner tube are provided on an
annular flange which protrudes radially therefrom, and this annular
flange is clamped between the upstream rolling bearing, spaced
apart from the outer assembly under the spacing action of the
spring member of the spacer element, and the downstream rolling
bearing which is retained by the annular stop surface of the outer
tube.
[0018] According to one particular embodiment of the invention, the
aforementioned outer tube is composed of two upstream and
downstream sections which are screwed to one another, the spacer
element bears between said upstream section and said upstream
rolling bearing, and the downstream section has said annular stop
surface on which the downstream rolling bearing bears. In this way,
due to the clamping which results from screwing these two upstream
and downstream sections together, the spring force of the spring
member of the spacer element is automatically applied to the inner
assembly at a specific value which can be predetermined.
[0019] According to one embodiment of the invention, said inner
tube of the inner assembly is held by said holder inside the outer
assembly at an upstream end, and, at its downstream end, it has an
outer thread capable of cooperating with an inner thread of another
inner tube of the inner assembly in order to fix this inner
assembly in an axially adjusted manner in a position of use.
[0020] The inner assembly can thus be adjusted to a suitable depth
relative to the outer assembly in order to remove the core, by
using just one single connecting thread, which greatly reduces the
risks of damage and jamming.
[0021] Since unscrewing may occur under the effect of the
vibrations, advantageously the core barrel additionally comprises a
threaded locking nut, arranged on said outer thread of said
downstream end of said inner tube, upstream of the other inner
tube, and, in said position of use, this locking nut is clamped to
a predetermined clamping torque against said other inner tube.
Preferably, the core barrel additionally comprises a locking washer
which, in said position of use, is clamped around said threaded
downstream end of said inner tube, between a threaded locking nut
and said other inner tube, this locking washer being arranged in
such a way as to prevent any unscrewing of the nut and of said
other inner tube on said threaded downstream end. Such a system,
which is effective, safe, compact and easy to use, ensures that the
clamping stress of the locking nut is maintained throughout the
entire core drilling process. This stress is constant and permanent
throughout the entire core drilling process. It therefore ensures
the filtration of the cyclic stresses associated with the
aforementioned axial vibrations, thereby considerably attenuating
the risks of wear of the aforementioned connecting thread due to a
mechanical fatigue phenomenon.
[0022] Further aspects of the invention are provided by way of a
tubular assembly, as defined in claim 15 below, and a method of
assembling tubular members, as defined in claim 18 below.
[0023] Other details and particular features of the invention will
emerge from the description of an exemplary embodiments of the
invention, said description being given below by way of example
only, with reference to the appended drawings, in which:-
[0024] FIGS. 1A and 1B together show a view in axial section of an
embodiment of a core barrel according to the invention;
[0025] FIG. 2 shows a view in axial section of a spacer element
used in the embodiment of FIGS. 1A and 1B;
[0026] FIGS. 3 and 4 show the installation of an embodiment of a
system for adjusting the position of the inner assembly relative to
the outer assembly of a core barrel according to the invention;
[0027] FIG. 5 shows a plan view of a locking washer of the
adjustment system of FIGS. 3 and 4; and
[0028] FIG. 6 shows a partial view in axial section of a variant
embodiment of a spacer element as may be used in a core barrel
according to the invention.
[0029] In the various figures, identical or analogous elements are
denoted by the same references.
[0030] The core barrel shown in FIGS. 1A and 1B comprises an outer
assembly formed of a plurality of outer tubes 1, 2 and 3 which are
screwed to one another, and of a core bit 4. From the surface, this
outer assembly is driven in rotation about the axis 5. The core
barrel additionally comprises an inner assembly formed of a
plurality of inner tubes 6, 7 and 8 which are screwed to one
another, and of core removal elements 9 which are known and are
shown schematically. Finally, a holder, in the illustrated example
two upstream and downstream roller bearings 10 and 11, are provided
for holding the inner assembly in the outer assembly. In this way,
these assemblies are reciprocally free in rotation, and the inner
assembly remains fixed in rotation while the outer assembly turns
about its axis. It would also be possible to provide more than two
rolling bearings, or even just one, between the two assemblies.
[0031] According to the example of embodiment shown in FIGS. 1A and
1B, the core barrel additionally comprises a spacer element 12
which is shown in detail in FIG. 2.
[0032] The spacer element 12 is housed inside the outer tube 1. In
the illustrated example, it comprises an upstream tubular part 13
which bears against the outer tube 1 and a downstream tubular part
14 which bears against the upstream rolling bearing 10. In this
example, the upstream tubular part 13 is provided with a female
tubular end piece 15 while the downstream tubular part 14 has a
male tubular end piece 16 which is capable of sliding axially
inside the cavity 17 of the aforementioned female end piece.
[0033] In the illustrated example of embodiment, a spring member 18
formed of a plurality of stacked frustoconical spring washers is
housed at the bottom of the cavity 17 of the upstream tubular part
13, bearing against the male tubular end piece 16 pushed into the
female tubular end piece 15.
[0034] Retaining features limit the possibilities of moving apart
and, in the illustrated case, simultaneously of bringing together
the upstream and downstream tubular parts 13 and 14. These
retaining features consist here of a plurality of elongate slots 19
provided in the axial direction on the female tubular end piece 15,
and of locking elements 20, in the form of bolts for example, which
are screwed into the male tubular end piece 16 so as to protrude
radially into the elongate slots 19. The ends of the elongate slots
19 serve as a stop for the locking elements 20 and thus limit a
moving-apart of the two parts of the spacer element, beyond a
predetermined value. A shoulder 35 is provided on the downstream
tubular part 14 so as to prevent the parts 13 and 14 from being
brought closer together beyond a certain limit.
[0035] By virtue of this arrangement, the axial vibrations which
may occur as the core barrel passes through hard geological layers
are effectively absorbed and damped by the spacer element.
[0036] As can be seen from FIGS. 1A and 1B, the holder for holding
the inner assembly in the outer assembly advantageously comprise,
as indicated above, two upstream and downstream rolling bearings 10
and 11 which are placed around the inner tube 6, in particular
around the upstream end thereof, and are arranged inside the outer
tube 1.
[0037] In this example of embodiment, the inner tube 6 carries
close to its upstream end an annular flange 21 which protrudes
radially therefrom. This flange is clamped between the two rolling
bearings 10 and 11. The downstream rolling bearing 11 is housed
between the downstream-facing annular bearing surface 22 of the
flange 21 and an annular stop surface 23 of the outer tube 1. The
upstream rolling bearing is arranged between the upstream-facing
annular bearing surface 24 of the flange 21 and the spacer element
12, in particular the downstream tubular part 14 thereof. The
spring member, by exerting its spacing action between the upstream
and downstream tubular parts 13 and 14 of the spacer element, has
the effect of pushing in the downstream direction the two rolling
bearings 10 and 11 and the flange clamped between them, the
downstream rolling bearing 11 being retained by the annular stop
surface 23 of the outer assembly.
[0038] Thus, in the case where the inner assembly ascends towards
the surface under the effect of axial vibrations, it can be
imagined that the downstream rolling bearing 11 may no longer be in
contact with the annular stop surface 23 or the annular bearing
surface 22, or even risks being dislocated due to a disconnection
of the elements constituting this downstream rolling bearing 11.
However, according to the invention, the upstream rolling bearing
10 takes over while, in addition, the spring member tends to oppose
this ascent.
[0039] As can be seen from FIGS. 1A and 1B, in the illustrated
example of embodiment, the outer tube 1 is composed of two
downstream and upstream sections 25 and 25'. These two sections are
joined to one another by a robust thread 26. The downstream section
25 has the upstream-facing annular stop surface 23. By a suitable
screwing of these two sections 25 and 25', it is possible to adjust
automatically the return force of the spring member 18 to an
appropriate specific value.
[0040] In the example of embodiment shown in FIGS. 1A, 1B, 3 and 4,
the core barrel comprises, in a known manner, a system for
adjusting the depth position of the inner assembly relative to the
outer assembly. At its upstream end, the inner tube 6 is held by
the rolling bearings 10 and 11 inside the outer assembly. At its
downstream end, it has an outer thread 27 capable of cooperating
with an inner thread of the next inner tube 7. This arrangement
makes it possible to fix the inner assembly at an adjustable depth
relative to the outer assembly. It should be noted that, in this
embodiment, there is a single thread, the outer thread 27, for
forming the connection between the outer assembly and the inner
assembly, and for adjusting the position of use of the core barrel.
The structure is therefore greatly simplified compared to the core
barrels according to the known prior art, which minimises the
possibilities for damage.
[0041] The outer thread 27 is preferably specially designed to be
on the one hand robust, so as to minimise the risks of wear on the
thread, and on the other hand particularly long, so as to have an
extended adjustment length for the inner assembly relative to the
outer assembly.
[0042] In order to prevent any unscrewing from occurring on the
adjustment system between the inner tubes 6 and 7 under the effect
of the vibrations, it is provided according to the invention to
arrange a locking nut 28 which is screwed onto the inner tube 6,
upstream of the inner tube 7. Once the position of the inner
assembly relative to the outer assembly has been adjusted, it is
then possible to screw the locking nut 28 against the inner tube 7
to a predetermined clamping torque. This nut substantially prevents
any unscrewing of the inner tubes 6 and 7 associated with the
vibrations, and thus reduces the causes of damage or breakage of
the outer (adjustment) thread 27.
[0043] Advantageously, as shown in detail in FIGS. 3 to 5, it is
possible to provide a locking washer 29 which, in the position of
use of the core barrel, is clamped between the locking nut 28 and
the upstream end of the inner tube 7. This washer is preferably
arranged so as to prevent any unscrewing of the locking nut 28 and
of the inner tube 7. In the illustrated example, the locking nut 28
has peripheral notches 30 and the upstream end of the inner tube 7
has peripheral notches 31. The locking washer 29 has corresponding
tabs 32 around its periphery. In the screwed position, some of the
tabs can be folded in the upstream direction into the notches 30
and some can be folded in the downstream direction into the notches
31, thus preventing any separation movement between the locking nut
28 and the inner tube 7.
[0044] In order that said washer is secured to the inner tube 6 in
the angular position while remaining free in terms of axial
displacement, two inner tabs 33 have been added to the washer 29 so
as to be housed in two axial recesses 34 provided for this purpose
on the inner tube 6. As soon as tabs 32 are engaged in the inner
tube 7 and the locking nut 28, these latter elements 7 and 28 are
thus advantageously held in an angularly fixed manner relative to
the inner tube 6.
[0045] It has also been found that, with a core barrel as designed
according to the invention, it became possible to eliminate the
seals which were usually required. Even the lubrication of the
outer adjustment thread 27 has in fact been found to be
unnecessary, and therefore a lubrication chamber at this location
has turned out to be superfluous. This therefore results in an
increased reliability of the system, and it is thus possible to
suppress the temperature limits for use of the core barrel in view
of the omission of seals made from rubber or plastomer
material.
[0046] It must be understood that the present invention is in no
way limited to the embodiment described above and that many
modifications can be made thereto within the scope of the appended
claims.
[0047] For example, according to one advantageous embodiment of the
invention, there can be envisaged a core barrel comprising an
additional spacer element 36, as shown in FIG. 6. The core barrel
of FIG. 6 is identical to the core barrel of FIGS. 1 to 5, except
in the respects illustrated in FIG. 6 and as described below.
[0048] As stated, the embodiment of FIG. 6 has additional spacer
element 36. In this example of embodiment, the additional spacer
element is a helical spring. The additional spacer element is to be
inserted between the downstream rolling bearing 11 and the
upstream-facing annular stop surface 23 of the outer tube 1. When
the two sections 25 and 25' of the outer tube 1 are screwed
together, the spring is prestressed, which makes it possible to
produce a vertical force, directed upwards, on the downstream
rolling bearing 11 and to keep the elements of this rolling bearing
11 in compression, so that they remain secured. In the event of
upward axial displacement of the inner assembly, the downstream
rolling bearing 11 is accompanied in this displacement and it is
not subject to any impact upon once again making contact with the
stop surface 23.
[0049] Although the above description has been made predominantly
with respect to a core barrel, the invention may find application
in other drilling apparatus where it is desired to provide axial
damping between relatively rotatable tubular members, and in cases
where it is desirable to be able to securely adjust the length
and/or relative position between threadedly connected tubular
members, such as drill string components and related equipment, for
example in a bottom hole assembly.
* * * * *