U.S. patent application number 12/530295 was filed with the patent office on 2010-05-06 for downhole tool.
This patent application is currently assigned to REAMERCO LIMITED. Invention is credited to Andrew Ollerenshaw, Mark Russell.
Application Number | 20100108394 12/530295 |
Document ID | / |
Family ID | 37988599 |
Filed Date | 2010-05-06 |
United States Patent
Application |
20100108394 |
Kind Code |
A1 |
Ollerenshaw; Andrew ; et
al. |
May 6, 2010 |
Downhole Tool
Abstract
A downhole tool (10') comprises a body (12') having a
longitudinal axis and a body through-bore (14'), a slot (34')
communicating the outside of the body with the body through-bore. A
sleeve actuator (30') mandrel also has a bore and is selectively
axially slidable in the body through-bore. A hollow bar (36') is
slidable with a radial component in the slot. At least two levers
(210), each pivoted to the mandrel (about a first axis
perpendicular the longitudinal axis) extend into the hollow bar and
are pivoted thereto (about a second axis parallel the first axis).
The levers lie in an actuation plane perpendicular the first and
second axes and containing the slot. The levers are disposed at an
inclined angle with respect to the longitudinal axis so that
longitudinal motion of the mandrel translates into radial movement
of the bar.
Inventors: |
Ollerenshaw; Andrew;
(Sheffield, GB) ; Russell; Mark; (Sheffield,
GB) |
Correspondence
Address: |
KEELING PATENTS AND TRADEMARKS, LLC
3310 KATY FREEWAY, 2nd Floor
HOUSTON
TX
77007
US
|
Assignee: |
REAMERCO LIMITED
Sheffield
GB
|
Family ID: |
37988599 |
Appl. No.: |
12/530295 |
Filed: |
March 10, 2008 |
PCT Filed: |
March 10, 2008 |
PCT NO: |
PCT/GB2008/000812 |
371 Date: |
September 8, 2009 |
Current U.S.
Class: |
175/284 ;
166/241.1; 175/325.1 |
Current CPC
Class: |
E21B 17/1014
20130101 |
Class at
Publication: |
175/284 ;
166/241.1; 175/325.1 |
International
Class: |
E21B 10/32 20060101
E21B010/32; E21B 17/10 20060101 E21B017/10; E21B 17/12 20060101
E21B017/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2007 |
GB |
0704484.5 |
Claims
1. A downhole tool comprising: a) a body having a longitudinal axis
and a body through-bore, a slot communicating the outside of the
body with the body through-bore; b) a sleeve actuator mandrel
having a sleeve actuator mandrel through-bore and being selectively
axially slidable in the body through-bore; c) a hollow bar slidable
with a radial component in the slot; and d) at least two levers,
each pivoted to said sleeve actuator mandrel about a first axis,
and each lever extending into said hollow bar and pivoted thereto
about a second axis parallel said first axis, wherein an actuation
plane of movement of said hollow bar on pivoting of the levers is
perpendicular said first and second axes and contains said
slot.
2. A downhole tool as claimed in claim 1, in which the first and
second pivot axes, at the intersection thereof with said actuation
plane, define a parallelogram.
3. A downhole tool as claimed in claim 1, in which said first and
second axes are perpendicular to a line parallel to said
longitudinal axis.
4-8. (canceled)
9. A downhole tool as claimed in claim 1, in which said sleeve
actuator mandrel has a port therethrough which aligns with a jet in
the body when the sleeve actuator mandrel is in its tool actuated
position, whereupon the through-bore of the sleeve actuator is in
fluid communication with said jet whereby drilling fluid under
pressure in said mandrel through-bore is directed onto the well
bore in the region of said bars.
10. A downhole tool as claimed in claim 1, in which the axis of the
slot is radial with respect to said longitudinal axis.
11. A downhole tool as claimed in claim 1, in which seals between
said sleeve actuator mandrel and body beyond both ends of said slot
define, between them, and a bar seal around the bar in the slot, a
chamber enclosing lubricating oil.
12. A downhole tool as claimed in claim 1, in which the levers are
captivated by pivot pins forming said first and second pivots
between the levers and the sleeve actuator mandrel and the hollow
bar respectively.
13. A downhole tool as claimed in claim 12, in which said pivot
pins are captured in blind bores in said hollow arms, said blind
bores being formed by elements inserted in said hollow arms.
14. A downhole tool as claimed in claims 12, in which a projection
of said pivot pins in the direction of said second pivot axis
intersects said bar seal.
15. A downhole tool as claimed in claim 13, in which said elements
are welded in said arms.
16. A downhole tool as claimed in claim 1, in which the levers are
pivoted to a flange connectable to the mandrel sleeve actuator.
17. A downhole tool as claimed in claim 16, in which said flange is
separate from the sleeve actuator mandrel but is locked thereon by
circumferential dovetailed slots formed on a sector of the sleeve
actuator mandrel adjacent an open sector thereof, and corresponding
dovetails on the base of said flange engaged with said dovetailed
slots of the sleeve actuator mandrel.
18. A downhole tool as claimed in claim 17, in which the tool is
assembled by inserting said flange engaged with said bar in said
slot so that said dovetails bear against said open sectors of the
sleeve actuator mandrel, and by rotating said mandrel so that said
dovetail slots engage said dovetails, means being provided to
prevent the sleeve actuator mandrel from rotating in the body
during use.
19. A downhole tool as claimed in claim 18, in which said rotation
prevention means comprises a pin in the body extending into a slot
in the sleeve actuator mandrel.
20. A downhole tool as claimed in 1, in which there are more than
two of said levers in parallel.
21-22. (canceled)
23. A downhole tool as claimed in claim 1, in which there are a
plurality, preferably three, of said bars and slots spaced around
the longitudinal axis of the tool.
24. A downhole tool as claimed in claim 23, in which said tool is
an under-reamer and said bars are provided with cutting elements to
effect under-reaming when the tool is actuated in a well bore
having a pilot hole receiving the tool.
25. A downhole tool as claimed in claim 24, in which said body is
thickened in the region of said slots and bars to support said
bars.
26. A downhole tool as claimed in claim 24, in which said body has
fins ahead of said slots having dimensions to match said pilot hole
and bear against its surface and stabilise the tool, in use, said
fins being provided with a hardened wear surface to minimise
wear.
27. A downhole tool as claimed in claim 23, in which the tool is an
adjustable stabiliser, said bars being provided with hardened wear
surfaces to minimise wear of the bars, in use.
28. A downhole tool as claimed in claim 1, in which the tool is an
azimuth controller, wherein one or more bars in one or more slots
are arranged asymmetrically around the longitudinal axis of the
tool.
29. A downhole tool as claimed in claim 28, further comprising one
or more static blades.
30. A downhole tool comprising: a) a body having a longitudinal
axis and a body through-bore, a slot communicating the outside of
the body with the body through-bore; b) a hollow bar slidable with
a radial component in the slot; c) a sleeve actuator having an
actuator through-bore and being axially slidable in the body
through-bore between a tool actuated position and a tool deactuated
position; d) a mandrel having a mandrel through-bore and being
selectively axially slidable in the body through-bore between a
tool actuated position, an interlock position and a sleeve-lock
position; and wherein: e) an extension of the mandrel is a close
sliding fit inside a first end of the sleeve actuator; f) said
first end captivates a lock element; g) said body has an internal
groove positioned so that, when said sleeve actuator is in said
tool deactuated position, said lock element is aligned with said
groove and held in engagement therein by said extension while the
mandrel is between its interlock and sleeve-lock positions; h) said
mandrel has an external recess positioned so that, when said
mandrel is in said interlock position, said lock element is aligned
with said recess, whereupon movement of the mandrel towards said
tool actuated position releases said lock element from said groove
permitting said sleeve actuator to be moved by the mandrel to said
tool actuated position, said mandrel and sleeve actuator being
locked together by the body holding said lock element in said
recess between said interlock and tool actuated positions of the
mandrel; and i) at least two levers, each pivoted to said sleeve
actuator mandrel about a first axis, and each lever extending into
said hollow bar and pivoted thereto about a second axis parallel
said first axis, wherein an actuation plane of movement of said
hollow bar on pivoting of the levers is perpendicular said first
and second axes and contains said slot.
31. A downhole tool as claimed in any of claims 30, in which said
lock element is a ball.
32. A downhole tool as claimed in claim 30, in which seals between
said sleeve actuator and body beyond both ends of said slot define,
between them, and a bar seal around the bar in the slot, a chamber
enclosing lubricating oil.
33. A downhole tool as claimed in claim 30, in which the levers are
captivated by pivot pins forming said first and second pivots
between the levers and the sleeve actuator and the hollow bar
respectively.
34. A downhole tool as claimed in claim 33, in which said pivot
pins are captured in blind bores in said hollow arms, said blind
bores being formed by elements inserted in said hollow arms.
35. A downhole tool as claimed in claim 30, in which the levers are
pivoted to a flange connectable to the mandrel sleeve actuator.
36. A downhole tool as claimed in claim 30, in which there are more
than two of said levers in parallel.
37. A downhole tool as claimed in claim 30, in which there are a
plurality, preferably three, of said bars and slots spaced around
the longitudinal axis of the tool.
38. A downhole tool as claimed in claim 37, in which said tool is
an under-reamer and said bars are provided with cutting elements to
effect under-reaming when the tool is actuated in a well bore
having a pilot hole receiving the tool.
39. A downhole tool as claimed in claim 38, in which said body is
thickened in the region of said slots and bars to support said
bars.
40. A downhole tool as claimed in claim 38, in which said body has
fins ahead of said slots having dimensions to match said pilot hole
and bear against its surface and stabilise the tool, in use, said
fins being provided with a hardened wear surface to minimise
wear.
41. A downhole tool as claimed in claim 37, in which the tool is an
adjustable stabiliser, said bars being provided with hardened wear
surfaces to minimise wear of the bars, in use.
42. A downhole tool as claimed in claim 30, in which the tool is an
azimuth controller, wherein one or more bars in one or more slots
are arranged asymmetrically around the longitudinal axis of the
tool.
43. A downhole tool as claimed in claim 42, further comprising one
or more static blades.
44. A downhole tool comprising: a) a body having a longitudinal
axis and a body through-bore, a slot communicating the outside of
the body with the body through-bore; b) a sleeve actuator having an
actuator through-bore and being axially slidable in the body
through-bore between a tool actuated position and a tool deactuated
position c) a mandrel having a mandrel through-bore and being
selectively axially slidable in the body through-bore between a
tool actuated position, an interlock position and a sleeve-lock
position; d) a hollow bar slidable with a radial component in the
slot; e) at least two levers, each pivoted to said sleeve actuator
mandrel about a first axis, and each lever extending into said
hollow bar and pivoted thereto about a second axis parallel said
first axis, wherein an actuation plane of movement of said hollow
bar on pivoting of the levers is perpendicular said first and
second axes and contains said slot. f) first means to lock the
sleeve actuator with respect to the body in said tool deactuated
position and while said mandrel is between said interlock and
sleeve-lock positions; and g) second means to lock the sleeve
actuator with respect to the mandrel and while said mandrel is
between said interlock and tool actuated positions.
45. A downhole tool as claimed in claim 44, in which said first and
second means comprise a lock element captivated by the sleeve
actuator and located in one of a groove in the body or a recess on
the mandrel.
46. A downhole tool as claimed in claim 45, in which alignment of
said groove and recess occurs in said interlock position of the
mandrel, which coincides with said tool deactuated position of the
sleeve actuator.
47. A downhole tool as claimed in claim 44, which said sleeve
actuator has ports therethrough which align with jets in the body
when the sleeve actuator is in its tool actuated position,
whereupon the through-bore of the sleeve actuator is in fluid
communication with said jets, and whereby drilling fluid under
pressure in said body through-bore is directed into the well
bore.
48. A downhole tool as claimed in claim 47, further comprising a
valve operated by the sleeve actuator to restrict drilling fluid
flow through the tool past said jets.
49. A downhole tool as claimed in claim 44, in which the levers are
captivated by pivot pins forming said first and second pivots
between the levers and the sleeve actuator and the hollow bar
respectively.
50. A downhole tool as claimed in claim 49, in which said pivot
pins are captured in blind bores in said hollow arms, said blind
bores being formed by elements inserted in said hollow arms.
51. A downhole tool as claimed in claim 44, in which the levers are
pivoted to a flange connectable to the mandrel sleeve actuator.
52. A downhole tool as claimed in claim 44, in which there are more
than two of said levers in parallel.
53. A downhole tool as claimed in claim 44, in which there are a
plurality, preferably three, of said bars and slots spaced around
the longitudinal axis of the tool.
54. A downhole tool as claimed in claim 53, in which said tool is
an under-reamer and said bars are provided with cutting elements to
effect under-reaming when the tool is actuated in a well bore
having a pilot hole receiving the tool.
55. A downhole tool as claimed in claim 54, in which said body is
thickened in the region of said slots and bars to support said
bars.
56. A downhole tool as claimed in claim 55, in which said body has
fins ahead of said slots having dimensions to match said pilot hole
and bear against its surface and stabilise the tool, in use, said
fins being provided with a hardened wear surface to minimise wear.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of, and priority to,
application number 0704484.5, which was filed in the United Kingdom
on Mar. 8, 2007, which application is incorporated herein by
reference as if reproduced in full below.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
FIELD OF THE INVENTION
[0003] The present invention relates to a downhole tool, in
particular an under-reamer.
BACKGROUND
[0004] Our pending international application publication number
WO2006/072761 (the entire disclosure of which is incorporated
herein by reference) discloses a downhole tool comprising: [0005] a
body having a longitudinal axis and a body through-bore, a slot
communicating the outside of the body with the body through-bore;
[0006] a sleeve actuator mandrel having a sleeve actuator mandrel
through-bore and being selectively axially slidable in the body
through-bore; [0007] a flange on the sleeve actuator mandrel
extending into said slot and having one of ribs and channels formed
on its sides and inclined at an acute angle to the longitudinal
axis; and [0008] a hollow bar slidable with a radial component in
the slots, the other of channels and ribs being formed on the bar
and corresponding with, and engaged in, said one of said ribs and
channels of the flange.
[0009] A result of this arrangement is that the actuating surfaces
of the tool, namely the interengaging ribs and channels, are
isolated from the drilling fluid. Seals may be provided between the
sleeve actuator mandrel and the body beyond both ends of the slot
and define, between them and seals around the bars in the slots, a
chamber enclosing lubricating oil. In this event, the mutually
engaging surfaces are primarily within the confines of the oil
chamber, where they are not only protected from contamination by
drilling fluid and debris, but also they are washed in lubricant to
facilitate their movement and to reduce wear.
[0010] An object of the present invention is to provide an
alternative arrangement that has the same benefits of this
arrangement.
[0011] U.S. Pat. No. 4,865,137 discloses an under-reamer in which
cutter arms are pivoted in the body of the tool and a pivot link
pivoted to the arm is urged by a hydraulically actuated control
piston to pivot each arm outwardly.
BRIEF SUMMARY OF THE DISCLOSURE
[0012] In accordance with a first aspect of the present invention,
there is provided a downhole tool comprising: [0013] a body having
a longitudinal axis and a body through-bore, a slot communicating
the outside of the body with the body through-bore; [0014] a sleeve
actuator mandrel having a sleeve actuator mandrel through-bore and
being selectively axially slidable in the body through-bore; [0015]
a hollow bar slidable with a radial component in the slot; and
[0016] at least two levers, each pivoted to said sleeve actuator
mandrel about a first axis perpendicular to a line parallel to said
longitudinal axis, and each lever extending into said hollow bar
and pivoted thereto about a second axis parallel said first axis,
wherein an actuation plane of movement of said hollow bar on
pivoting of the levers is perpendicular said first and second axes
and contains said slot, and the first and second pivot axes at the
intersection thereof with said actuation plane define a
parallelogram.
[0017] Thus, when the sleeve actuator mandrel is actuated to move
along said longitudinal axis from a deactuated to an actuated
position thereof, said levers are pivoted about their first axes to
increase the radial position of said second axes with respect to
said longitudinal axis, and whereby said bar slides with a radial
component in said slot
[0018] A return mechanism is provided to guarantee that the bars
return to their deactuated position when this is selected. Usually,
the strongest mechanism is utilized to actuate tools, because this
will generally involve contact with the hole bore (to start
cutting, for example, with an under-reamer), whereas retraction is
generally not opposed. On the other hand, when components get worn
or contorted by their interaction with the bore hole, they may be
difficult or impossible to withdraw.
[0019] This might be very problematic with an under-reamer where,
to get the tool out through a narrow casing above the reamer, the
reamer must be withdrawn (deactuated). Consequently, the levers may
be captivated by pivot pins forming said first and second pivots
between the levers and the sleeve actuator mandrel and the hollow
bar respectively. Thus the sleeve actuator mandrel cannot return to
its deactuated position without withdrawing the hollow bar into its
slot.
[0020] Said sleeve actuator mandrel may comprise a separate mandrel
and sleeve actuator, the sleeve actuator having an actuator
through-bore and being axially slidable in the body through-bore
between a tool actuated position and a tool deactuated position,
the mandrel having a mandrel through-bore and being selectively
axially slidable in the body through-bore between a tool actuated
position, an interlock position and a sleeve-lock position;
wherein: [0021] an extension of the mandrel is a close sliding fit
inside a first end of the sleeve actuator; [0022] said first end
captivates a lock element; [0023] said body has an internal groove
positioned so that, when said sleeve actuator is in said tool
deactuated position, said lock element is aligned with said groove
and held in engagement therein by said extension while the mandrel
is between its interlock and sleeve-lock positions; and [0024] said
mandrel has an external recess positioned so that, when said
mandrel is in said interlock position, said lock element is aligned
with said recess, whereupon movement of the mandrel towards said
tool actuated position releases said lock element from said groove
permitting said sleeve actuator to be moved by the mandrel to said
tool actuated position, said mandrel and sleeve actuator being
locked together by the body holding said lock element in said
recess between said interlock and tool actuated positions of the
mandrel.
[0025] Put another way, first means may lock the sleeve actuator
with respect to the body in said tool deactuated position and while
said mandrel is between said interlock and sleeve-lock positions;
and [0026] second means may lock the sleeve actuator with respect
to the mandrel and while said mandrel is between said interlock and
tool actuated positions.
[0027] Separating the mandrel from the sleeve actuator permits them
to move independently when for some stroke movements of the mandrel
which is needed for switching between actuation mode and
deactuation mode of the tool. Generally, a strong return spring is
utilized and, by connecting the mandrel with the sleeve actuator
during some movements thereof, the return spring for the mandrel
can also serve as the return spring for the bars. Since it is
normal to provide signalling in the form of pressure pulses, at
least when the tool is actuated, then, by connecting the mandrel to
the tool actuator, signalling by the mandrel equates to signalling
by the tool, at least when they are interconnected.
[0028] Said sleeve actuator mandrel may have a port therethrough
which aligns with a jet in the body when the sleeve actuator
mandrel is in its tool actuated position, whereupon the
through-bore of the sleeve actuator is in fluid communication with
said jet, and whereby drilling fluid under pressure in said mandrel
through-bore is directed onto the well bore in the region of said
bar.
[0029] Indeed, the applications disclosed herein are not limited to
under-reamers. Adjustable stabilisers could benefit from the
invention.
[0030] Seals between said sleeve actuator mandrel and body beyond
both ends of said slot define, between them, and a bar seal around
the bar in the slot, a chamber enclosing lubricating oil.
[0031] The levers may be pivoted to a flange connectable to the
mandrel sleeve actuator. Preferably there are more than two of said
levers in parallel. The levers are captivated by pivot pins forming
said first and second pivots between the levers and the sleeve
actuator mandrel and the hollow bar respectively. Said pivot pins
are captured in blind bores in said hollow arms, said blind bores
being formed by elements inserted in said hollow arms. Said
elements may be welded in said arms. This is desirable because said
seal around the arm which seals the arm in said slot is preferably
in the same region as the pivots between said levers and arms. That
is to say, a projection of said pivot pins in the direction of said
second pivot axes preferably intersects said bar seal. Therefore,
should the pivot pins be located in through bores of the arms, the
pins would interfere with operation of the seal.
[0032] There are a plurality, possibly three, of said bars, slots
and flanges spaced around the longitudinal axis of the tool.
[0033] Where the tool is an under-reamer, said bars are provided
with cutting elements to effect under-reaming when the tool is
actuated in a well bore having a pilot hole receiving the tool.
[0034] Said body is thickened in the region of said slots and bars
to support said bars. The body may have fins ahead of said slots
having dimensions to match said pilot hole and bear against its
surface and stabilise the tool, in use, said fins being provided
with a hardened wear surface to minimise wear.
[0035] Alternatively, the tool may be an adjustable stabiliser,
said bars being provided with hardened wear surfaces to minimise
wear of the bars, in use.
[0036] Furthermore, the tool may be an azimuth controller, in which
one or more bars in one or more slots are arranged asymmetrically
around the longitudinal axis of the tool. The tool may also
comprise one or more static blades.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Embodiments of the invention are further described
hereinafter, by way of example only, with reference to the
accompanying drawings, in which:
[0038] FIGS. 1a, b and c are side sections through an under-reamer
in accordance with the invention in WO2006/072761 in sleeve lock,
interlock and tool actuated positions respectively;
[0039] FIGS. 2a.sub.1, a.sub.2, b and c are views of a variation of
the tool shown in FIGS. 1a to c, in corresponding positions, but
also in greater detail;
[0040] FIGS. 3a and b are sections along the lines A-A and B-B in
FIGS. 1a and 1c respectively;
[0041] FIGS. 4a to d are, respectively two side views, in the
directions of Arrows A and B in FIG. 4d, a section on the line A-A
in FIG. 4a, and an end view in the direction of the Arrow D in FIG.
4b, of a tool in accordance with the teachings herein, in a
deactuated position thereof;
[0042] FIGS. 5a to d are, respectively two side views, in the
directions of Arrows A and B in FIG. 5d, a section on the line B-B
in FIG. 5a, and an end view in the direction of the Arrow D in FIG.
5b, of the tool shown in FIGS. 4a to d, but in an actuated position
thereof; and
[0043] FIGS. 6a to f are, respectively a side view, and end view in
the direction of Arrow B in FIG. 6a, a section on the line C-C in
FIG. 6b, a section on the line D-D in FIG. 6a, a section on the
line E-E in FIG. 6a, and a perspective, transparent view of an arm
and lever mechanism for the tool shown in FIGS. 4 and 5.
DETAILED DESCRIPTION
[0044] In FIGS. 1 to 3 of the drawings, an under-reamer 10
comprises a body 12 having a through-bore 14 along a longitudinal
axis 50 of the tool 10. A mandrel 16 actuates the tool 10 and is a
component of an actuation mechanism 18, only one end of which is
shown in the drawings. The actuation mechanism 18 is connected at
its end 18a to end 12a of the body 12 by a standard screw thread
connection 20a. The other end 12b of the tool 10 comprises a female
connection 20b.
[0045] The actuation mechanism 18 forms no part of the invention
and may be in the form disclosed in WO-A-00/53886, U.S. Pat. No.
5,483,987, U.S. Pat. No. 6,289,999 (the entire disclosures of which
are incorporated herein by reference), or any suitable means.
Connected to the end of the mandrel 16 is mandrel end 22, which,
conveniently, is screw threaded to the mandrel 16. However, in
suitable circumstances end 22 may be integral with the mandrel 16
and henceforth is considered a part of the mandrel 16. In the
drawings, mandrel 16, and its end 22, is shown in three positions.
In FIG. 1a, it is shown in a sleeve-lock position. In FIG. 1b, it
has moved axially rightwardly in the drawings to an interlock
position and, in FIG. 1c, it has moved further rightwardly to a
tool actuated position. The above positions are described further
below.
[0046] The tool 10 further comprises a sleeve actuator 30 which
also has a sleeve through-bore 32. Therefore, it can be seen that a
clear passage comprising mandrel through-bore 24, sleeve
through-bore 32, and body through-bore 14 through the tool 10
permits unimpeded passage of drilling fluid to a drill bit (not
shown) connected to the tool 10.
[0047] Neither end 12a, b of the tool 10 is necessarily nearer the
drill bit. However, for reasons explained further below, in the
present arrangement, end 12a of the tool 10 is preferably arranged
nearest the drill bit.
[0048] The body 12 is provided with three axially disposed,
circumferentially spaced slots 34a, b, c, only 34a of which is
visible in FIGS. 1a to 1c. Each slot receives a radially slidable
cutter bar 36a, b, c. Although radial, there is no reason why the
axis of the slots 34 should not be inclined to the radial. The top
surface 38 of each cutter bar is provided with cutting elements,
further details of which are not given herein. Suitable form of
cutting elements will be known to those skilled in the art. One
arrangement is shown in U.S. Pat. No. 6,732,817 (the full
disclosure of which is herein incorporated by reference). Each
cutter bar 36 is hollow, with an interior space or pocket 46. The
interior sides 40a, b (which sides are parallel the longitudinal
axis 50) are formed with ribs 42 which are inclined with respect to
the axis 50.
[0049] The actuator sleeve 30 is provided with three flanges 44a,
b, c which are received within the pockets 46 of the hollow bars
36. The flanges 44 are each provided with channels 48 which are
also inclined with respect to the longitudinal axis 50 and which
cooperate with the ribs 42 in the sides 40a, b of the pocket 46.
Indeed, the channels 48 define ribs between them, as do the ribs 42
define channels between them.
[0050] With reference to FIGS. 3a and b, the actuator sleeve 30
has, on its external surface, three open sections 52a, b, c. On
assembly of the tool 10, these sections are aligned with the slots
34a, b, c respectively. Each bar 36 with its corresponding flange
44 is then inserted through the slots 34 until a dovetailed base of
the flanges 44 abut the open sections 52. The actuator sleeve 30 is
also provided with three dovetail sections 56a, b, c disposed
between each open section 52a, b, c. When correctly aligned, the
sleeve 30 is rotated through 60.degree. about the longitudinal axis
50. An hexagonal section of a nose 31 at second end 67 of the
sleeve actuator 30 is adapted to receive a tool for this purpose.
Dovetails 58 on the dovetailed sections 56 of the sleeve actuator
30 then lock with corresponding dovetails 60 on the dovetailed base
of the flanges 44. In this way, the flanges 44 are locked to, and
become an integral part of, the actuator sleeve 30. However, it is
required to ensure that the sleeve 30, in operation, does not
rotate about axis 50 relative to the slots 34, otherwise this will
disengage the dovetails 58, 60. For this purpose, a drilling 64
(64' in FIG. 2a.sub.2) in the body 12 is adapted to receive a pin
(not shown) adapted to slide in a longitudinal groove 63 on the
surface of the sleeve 30. Thus the sleeve 30 is constrained
rotationally about the longitudinal axis 50 but is free to move
axially.
[0051] When the actuator sleeve 30 does move axially, as it does
between the positions shown in FIGS. 1b and 1c, the ribs/channels
42,48 on the flanges 44 and inside the bars 36 interact to radially
displace the bars 36 from a stowed, deactuated position (as shown
in FIGS. 1a and b), and where the bars are within the confines of
the slots 34, to an actuated position as shown in FIG. 1c. Here,
the bars 36 can bear against and cut the well bore (not shown).
[0052] The actuator sleeve 30 is controlled by the mandrel 16. The
mandrel end 22 has a cylindrical extension 62 which is a close
sliding fit in sleeve 30 at its first end 65. On the end 65 are
formed a number of pockets 66 which each receive a lock element in
the form of a ball 68. A shoulder 70 is provided in the body 12 and
the lock elements 68, sitting on the cylindrical surface of the
extension 62, prevent the sleeve 30 from moving rightwardly by
engaging the shoulder 70. The sleeve is therefore in a sleeve-lock
position because the lock elements 68 prevent any rightward
movement of the sleeve 30, while the flanges 44 are at their
leftmost position, in which the bars 36 fully withdrawn into the
slots 34.
[0053] In this position, the mandrel 16 is free to move between the
positions shown in FIG. 1a and the position shown in FIG. 1b
without affecting the position of the sleeve 30. However, when the
mandrel 16 is moved rightwardly to an interlock position as shown
in FIG. 1b, recesses 72 on the surface of the mandrel extension 62
align with the lock elements 68. They are consequently released
from engagement with the shoulder 70. Now, further rightward
movement of the mandrel moves the actuator sleeve 30 rightwardly in
the drawing to actuate the bars 36.
[0054] Between the interlock position shown in FIG. 1b and the tool
actuated position shown in FIG. 1c, the internal cylindrical
surface 74 of the body 12 locks the lock elements 68 in the recess
72 of the mandrel. Thus, the mandrel is locked to the actuator
sleeve 30. Consequently, when the mandrel returns leftwardly in the
drawings from the FIG. 1c position, the actuator sleeve 30 is
constrained to follow it.
[0055] This arrangement is also shown in greater detail in FIGS. 2a
to c. A difference, however, between the embodiment shown in FIGS.
1a to c is that, here, the shoulder 70 is replaced by a
circumferential groove 70'.
[0056] A circumferential gallery 82 is provided around the body
bore 14, adjacent the ends of the slots 34. Each slot 34 has an
associated jet 84a, b, c (only jet 84a being visible in the
drawings). The jets 84 communicate with the gallery 82. The gallery
82 is sealed to the external surface of the sleeve 30 by seals 86a,
b. The sleeve 30 is provided with a number of apertures or ports
88. These put the sleeve bore 32 in fluid communication with its
external surface. In the deactuated position of the actuator sleeve
30 (FIGS. 1a and 2a.sub.1), the apertures 88 are sealed by seals
86a and further seals 86c in the body bore 14. However, when the
actuator sleeve 13 moves into its actuated position as shown in
FIGS. 1c and 2c, the ports 88 communicate with the gallery 82 so
that drilling fluid under pressure in the actuator sleeve bore can
escape to the outside through the ports 88, gallery 82 and jets 84.
In issuing from the jets 84, the drilling fluid serves to clear
debris caused by the action of the cutters 36 against the well
bore.
[0057] Each slot 34 is not rectangular in section but has rounded
ends 34d, 34e. The bars 36 are correspondingly rounded at their
ends and a circumferential groove 90 is formed around the entire
periphery of each bar in which a seal (not shown) is disposed.
[0058] At its second end 67, the sleeve 30 is received within a
liner 92 of the body 12. The liner 92 is sealed to the body 12 by
seal 94 and the end 67 is sealed to the liner 92 by seal 96. Thus,
between the seals 86b, seals 94,96, and seals 90 around the bars
36, an oil chamber 102 is defined. This can be filled with
lubricating oil through a tapping 98 and longitudinal groove 100 in
liner 92. In use and after filling, tapping 98 is plugged by means
not shown.
[0059] Thus the interacting surfaces of the flanges 44 and bars 36
(that is to say, the ribs/channels 42,48), as well as the external
surfaces of the bars 36 against the slots 34, and the sliding of
the sleeve actuator 30 in the body through-bore 14, are all
facilitated by the lubrication. This serves to reduce wear. Also,
drilling fluid, particularly that in the annulus surrounding the
tool 10 inside the well-bore, is isolated from these components so
that the risk of jamming by hard particles carried by the drilling
fluid is reduced.
[0060] However, it will be appreciated that the volume of the
chamber 102 changes as the radial position of the bars 36 changes,
not to mention the axial position of the sleeve actuator 30.
Therefore, several longitudinally arranged drillings 104 are spaced
around the circumference of the end 65 of the sleeve actuator 30.
These are positioned both to avoid the ports 88 and the pockets 66
and therefore should not strictly be visible in the drawings.
However, they are shown in FIGS. 2a.sub.1, b and c for illustrative
purposes.
[0061] Drillings 104 connect the chamber 102 with the annulus 106
in actuation mechanism 18 and surrounding mandrel 16. The pressure
in the annulus 106 is released by a bladder arrangement 108,
further details of which are not given as its essential structure
is well understood in the art.
[0062] The drillings not only relieve pressure in the chamber 102
but also serve to damp movement of the sleeve actuator 30. They
also supply the interlock arrangement 72,68,70 with lubricant to
facilitate its action as well.
[0063] Beyond the pressure relief bladder arrangement 108, a
mandrel return spring 110 is visible. Although not shown
completely, spring 110 acts between bladder 108 fixed in the body
of mechanism 18 and a shoulder on the mandrel 16, urging it
leftwardly in the drawings (see FIG. 2a.sub.1).
[0064] As mentioned above, the direction of orientation in a well
bore of the tool 10 is not absolutely determined by its structure:
it will operate in either direction; at least, it will if the
actuation mechanism 18 operates on fluid pressure. However, it is
preferred that it be arranged with the end 12a closest to the drill
bit for three reasons. The first is that the jets 84 are more
effective being directed immediately at the cutting interface
between the cutters 36 and the well bore. Secondly, in the event
that the bars 36 (or one of them), jam in their slots 34 and the
normal deactuation force applied by the mandrel return spring is
inadequate to overcome the jamming, then pulling the tool 10 up
against the under edge of the casing (not shown) is considered more
likely to nudge the jammed bar(s) back into the slots 34 than from
the other direction. Thirdly, in the event of jamming, it would be
possible to drop a ball down the well bore so that it closes the
end of nose 31 of the sleeve actuator 30. Then, hydraulic pressure
above the actuator can supplement the force applied by the mandrel
return spring 110.
[0065] It is to be noted that there are shown in the drawings three
circumferentially spaced bar/flange/slot combinations around the
tool. This is for illustrative purposes. The invention includes the
possibility of more or less. The possibility of a tool with just
one bar exists in the application of an azimuth controller, where
it is desired to deflect the drill-string to one side of the well
bore so that the azimuth of a motor assembly in the string may be
adjusted.
[0066] In the case of a stabiliser, the bars 36 are not provided
with cutting elements, as shown, but with hardened wear
surfaces.
[0067] The body 12 is provided with thickened regions 114 to
support the slots 34 and bars 36. From another perspective, the
tool has thinned regions, where the extra thickness of the body is
not required!
[0068] In the case of the under-reamer, the thickened regions 114
ahead (in the drilling direction) of the slots 34 have an enlarged
diameter surface 116 which is provided with hardened wear elements.
In use, the tool here bears against the pilot hole formed by the
drill bit on the end of the drill string (not shown) and stabilises
the under-reamer keeping it central with respect to the pilot
hole.
[0069] Turning to FIGS. 4 to 6, an under-reamer 10' is shown of
similar overall construction to the under-reamer 10 of FIGS. 1 to
3. Like parts are given the same reference number, except with an
apostrophe. Thus, with reference to FIG. 4c, the under-reamer 10'
comprises a body 12' having a through-bore 14' and including a
sleeve actuator 30'. The mandrel is not visible in these
drawings.
[0070] Slots 34a' are provided in thickened regions 114' of the
body 12'. Hollow arms 36' slide in the slots 34a'. A flange 44' is
similarly connected with the sleeve actuator 30' by corresponding
inter-engaging dovetails 58', 60'. However, the flange 44' mounts a
series of parallel levers 210 pivoted in a line to the flange 44'
about pivot pins 212. The axes of the pivot pins 212 are
substantially perpendicular to the longitudinal axis 50 of the tool
(or at least, perpendicular to a line (not shown) parallel the
longitudinal axis 50) and also substantially perpendicular to
respective ones of the radial planes 50a, b, c that contain the
longitudinal axis 50, and which also contain the respective slot
34'a, b, c of the respective bar 36'.
[0071] The levers 210 are also pivoted about pivot pins 214 to the
bars 36'. In FIG. 4c, the sleeve actuator 30' is shown in its
tool-de-actuated position. Here, the levers 210 are at a minimum
inclination with respect to the longitudinal axis 50. This
inclination is of about 25.degree.. When the tool is actuated,
however, the sleeve actuator 30' moves from the position shown in
FIG. 4c to that shown in FIG. 5c. Here, the levers 210 have been
pivoted in an anti-clockwise direction about their axes 212 to
adopt almost an orthogonal position with respect to the
longitudinal axis 50. Given that this results in a radial extension
of the ends of the levers connected to pivot pins 214, the bars 36'
are pushed out of the slots 34'a, b, c, in this movement, as can be
seen in FIG. 5d. This occurs, of course, because the bars 36' are
unable to move axially in the slots 34'a, b, c and therefore can
only move radially. An advantage of this arrangement is that, when
the bars 36' are extended to their maximum extension, and therefore
most liable to suffer damage from contact with the bore wall and
the like, the maximum refraction force is imposed on the arms 36'
when the actuator sleeve 30' begins to move from the tool-actuated
position shown in FIG. 5c towards the tool-de-actuated position of
FIG. 4c. Moreover, at the first stages of this movement, there is
little axial component of the forces on the bar 36', and therefore
less risk of the bar jamming in the slot 34'a, b, c. When the
actuator sleeve 30' approaches the position in FIG. 4c then, while
the geometry becomes unfavourable for further withdrawal of the
bars 36', nevertheless, by the time this position is reached, the
bars have been withdrawn to a significant extent.
[0072] Turning to FIGS. 6a to f, the structure of the bars 36',
flange 44', and the levers 210 is more evident. Flange 44' is a
saddle shaped component with a hollow interior 44'a, forming seats
or pockets for the levers 210. Pivot pins 212 pass through
apertures 216 in the side of the flange 44', as well as through
bores 218 in the ends of the levers 210.
[0073] The other ends of the levers 210 likewise have eyes 220
receiving their pivot pins 214. These pins are journalled in
carrier elements 222 which are welded along line 224 to the inside
of the pocket 46' of the arm 36'. This enables the exterior of the
arm 36' to be unbroken. The benefit of this is that the axial
projection of the pivot pins 214 coincides with the region of the
outside surface of the bars 36' where circumferential seal 90 is
located. If eyes 228 which support the pins 214 penetrated to the
surface, they may compromise the seals 90. Consequently, the bores
228 are "blind". It is to be noted that the levers 210 are all
substantially parallel. Moreover, the quadrilateral 250 defined by
the axes of the pivots 212,214 where they intersect the plane 50a,
b, c of actuation of the bars 36', is a parallelogram. This ensures
that the surface of the bars 36' maintain a constant orientation
with respect to the bore wall. The parallelogram lies in the plane
of actuation of the bar 36', which in the drawings comprises a
respective one of the radial planes 501, b, c.
[0074] However, apart from the simplicity of the design, there is
no absolute reason why the bars 36' and slots 34'a, b, c must be
radial (in the sense that movement of the bars in the slots must be
orthogonally radial with respect to the longitudinal axis 50), or
even in an actuation plane that is parallel the longitudinal axis.
Similarly, the levers do not necessarily need to be the same length
or define a parallelogram. On the contrary, there are several
alternative possibilities although these are not preferred as they
add considerable complication to the design without necessarily
providing any obvious benefit.
[0075] Thus, the actuation plane could be inclined to some degree
with respect to the longitudinal axis. This would result in an
helically arranged bar 36'. In this event, some sliding connection
between the flange 44' and the actuator sleeve 30' would be
required, or some rotation of the sleeve 30' must be provided, to
enable the movement to occur. The slot would also have to have a
helical form.
[0076] The actuation plane may be parallel the longitudinal axis,
but spaced from it, so that the slots 34'a have a somewhat
tangential orientation, rather than a radial one.
[0077] The slot 34'a in side section is rectangular in the
embodiments described above. However, it could be a parallelogram
itself, whereby movement of the bars 36' is not radial but also
axial to some extent. This might provide a useful feature if the
inclination of the slot was upwardly oriented with respect to the
borehole in which the tool is employed. Then, should the tool jam,
knocking the extended arms onto the bottom of a casing or narrower
bore through which the tool is to be retrieved, will have the
effect of knocking the arms back into their slots. This might be
deemed desirable in some cases.
[0078] The levers 210 need not be the same length. In this case the
arms 36' move in an arc, rather than in a straight line.
[0079] Throughout the description and claims of this specification,
the words "comprise" and "contain" and variations of the words, for
example "comprising" and "comprises", means "including but not
limited to", and is not intended to (and does not) exclude other
moieties, additives, components, integers or steps.
[0080] Throughout the description and claims of this specification,
the singular encompasses the plural unless the context otherwise
requires. In particular, where the indefinite article is used, the
specification is to be understood as contemplating plurality as
well as singularity, unless the context requires otherwise.
[0081] Features, integers, characteristics, compounds, chemical
moieties or groups described in conjunction with a particular
aspect, embodiment or example of the invention are to be understood
to be applicable to any other aspect, embodiment or example
described herein unless incompatible therewith.
[0082] The reader's attention is directed to all papers and
documents which are filed concurrently with or previous to this
specification in connection with this application and which are
open to public inspection with this specification, and the contents
of all such papers and documents are incorporated herein by
reference.
[0083] All of the features disclosed in this specification
(including any accompanying claims, abstract and drawings), and/or
all of the steps of any method or process so disclosed, may be
combined in any combination, except combinations where at least
some of such features and/or steps are mutually exclusive.
[0084] Each feature disclosed in this specification (including any
accompanying claims, abstract and drawings), may be replaced by
alternative features serving the same, equivalent, or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
[0085] The invention is not restricted to the details of any
foregoing embodiments. The invention extends to any novel one, or
any novel combination, of the features disclosed in this
specification (including any accompanying claims, abstract and
drawings), or to any novel one, or any novel combination, of the
steps of any method or process so disclosed.
* * * * *