Canadian Patents Database / Patent 2344631 Summary

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(12) Patent: (11) CA 2344631
(54) English Title: BENT SUB ASSEMBLY FOR DIRECTIONAL DRILLING
(54) French Title: SOUS-ENSEMBLE INCLINE POUR FORAGE DIRIGE
(51) International Patent Classification (IPC):
  • E21B 7/08 (2006.01)
  • E21B 7/06 (2006.01)
(72) Inventors :
  • ROBIN, LAWRENCE E. (Canada)
(73) Owners :
  • CAVARE LTD. (Canada)
(71) Applicants :
  • ROBIN, LAWRENCE E. (Canada)
(74) Agent: JOHNSON, ERNEST PETER
(74) Associate agent: PARLEE MCLAWS LLP
(45) Issued: 2005-09-13
(22) Filed Date: 2001-04-18
(41) Open to Public Inspection: 2002-10-18
Examination requested: 2001-04-18
(30) Availability of licence: N/A
(30) Language of filing: English

English Abstract

An adjustable bent sub assembly is provided comprising a tubular adaptor for connection with the stator of a downhole motor, a tubular adjusting ring for altering the angular offset of the assembly, and a tubular offset sub for connection with the bearing and bit assemblies. A tubular mandrel is positioned internal of this stack of components. The mandrel is threadably connected at its upper end with the adaptor and at its lower end with the offset sub. The mandrel and ring have a spline connection. The ring and offset sub have disengagable dog clutch means connection them. The mandrel is transversely bent at a point along its length as is the offset sub. The ring has an angled or canted bottom end face. The combination of bending the internal mandrel, bending the offset sub and canting the end face of the ring results in the effective or resultant bend point of the assembly being closer to its lower end.


French Abstract

L'invention concerne un sous-ensemble courbé, comprenant un adaptateur tubulaire pour le raccordement avec le stator d'un moteur de fond, une bague de réglage tubulaire pour modifier le décalage angulaire de l'ensemble, et un sous-décalage tubulaire pour le raccordement avec le support et les ensembles de forets. Un mandrin tubulaire est placé à l'intérieur de cette pile d'éléments. Le mandrin est relié par filetage à son extrémité supérieure avec l'adaptateur et à son extrémité inférieure avec les sous-décalages. Le mandrin et la bague sont munis d'un accouplement à cannelures. La bague et les sous-décalages sont raccordés au moyen d'un embrayage à griffe déclenchable. Le mandrin est transversalement courbé en un point de sa longueur, comme le sous-décalage. La bague présente une face d'extrémité inférieure inclinée ou penchée. La combinaison de la flexion du mandrin interne, de la flexion du sous-décalage et de l'inclinaison de la face d'extrémité de la bague fait que le point de pliage effectif ou résultant de l'ensemble est plus proche de son extrémité inférieure.


Note: Claims are shown in the official language in which they were submitted.


9


THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A bent sub assembly for directional drilling, comprising:
an external tubular adaptor having an internally threaded lower end;
an internal tubular mandrel having externally threaded ends and being
transversely bent at a point along its length to define upper and lower
mandrel
sections having angularly offset axes of symmetry, the upper mandrel section
being received in the adaptor lower end and being threadably connected
therewith;
an external tubular offset sub transversely bent at a point along its length
and at the lower end of the mandrel to define upper and lower sub sections
having
angularly offset axes of symmetry, the upper sub section being internally
threaded
at its upper end and coaxially receiving the lower mandrel section and being
threadably connected therewith, the offset sub having an upper end face
perpendicular to the axis of symmetry of the upper sub section;
an external tubular adjusting ring having an axis of symmetry and being
positioned around the mandrel and between and abutting the adaptor and the
offset sub, the ring being slidably splined with the mandrel, the ring having
a lower
end face canted at an angle to the axis of symmetry of the ring;
the offset sub upper end face and the ring lower end face being disposed to
butt flush against each other when assembled;


10


the combination, of bending the internal mandrel, bending the offset sub
and canting the lower end face of the ring, resulting in locating an effective
bend
point of the bent sub assembly beneath the ring.
2. The bent sub assembly as set forth in claim 1 wherein:
the ring and offset sub have clutch means for disengagably locking them
together for rotation, the ring being rotationally adjustable when the clutch
means
are disengaged.

Note: Descriptions are shown in the official language in which they were submitted.

CA 02344631 2001-04-18
1 "BENT SUB ASSEMBLY FOR DIRECTIONAL DRILLING"
2 FIELD OF THE INVENTION
3 The present invention relates to a bent sub assembly for use in directional
4 drilling.
BACKGROUND OF THE INVENTION
7 Bent sub assemblies are used to change the direction in which a drilling bit
8 cuts the borehole. The bent sub assembly has a transverse bend at a point
along
9 its length. The assembly is commonly positioned between the power section of
a
downhole motor and a bearing assembly , to which the bit is connected. At its
11 upper end, the bent sub assembly is coaxial with the longitudinal axis of
the power
12 section and the drill string, but beneath the bend the longitudinal axis of
the lower
13 end of the bent sub assembly and the bearing assembly attached thereto is
offset
14 at a slight angle (typically up to 3°').
It is known to those skilled in the art that it is desirable to locate the
bend of
16 the bent sub assembly as close to the bit as possible. Every inch counts.
The
17 distance of the bend from the bit will affect the "aggressiveness" and
control of the
18 drilling assembly. If the bend is closer to the bit, the drilling assembly
will "build
19 angle" or change direction more quickly than it will if the bend is further
from the
bit.
21 It is the purpose of the present invention to provide a bent sub assembly
22 having an effective or resultant bend point which is close to the lower end
of the
23 assembly, and thus to the bit.
{EM130354.DOC;1 }

i i i ~ il ii I I i ~. ~ I
CA 02344631 2004-12-06
2
1
2 SUMMARY OF THE INVENTION
3 In accordance with the invention an adjustable, tubular bent sub assembly
4 is provided having two bends at spaced points along its length, so that the
assembly has a resultant or effective bend point close to its lower end. The
bent
6 sub assembly has longitudinal axes of symmetry at its upper and lower ends
which
7 are angularly offset. The assembly further has means for adjusting the
extent of
8 the angular offset.
9 More particularly, in a preferred embodiment, the tubular bent sub assembly
l0 comprises:
11 ~ an internal mandrel which is threadably connected at its upper and lower
12 ends with an external adaptor and an external offset sub, respectively,
13 the mbndrel further being disengagably locked by splines or the like with
14 an external adjusting ring positioned around the mandrel and between
the adaptor and the offset sub, the lower end of the adjusting ring being
16 connected with the upper end of the offset sub by axially disengagable
17 clutch means, so that the assembled components form a solid unit for
18 transmitting rotation from a power unit or downhole motor assembly to a
19 drill bit assembly;
~ the offset sub is positioned at the base of the assembly and has a
21 transverse bend at a point along its length, adjacent the bottom of the
22 mandrel, thereby defining upper and lower sub sections above and
23 below the bend, each sub section having a longitudinal axis of
{E4254'788.DOC;1 J

" ., ,"" " .
CA 02344631 2004-12-06
2a
1 symmetry, the axis of the upper sub section being perpendicular to the
2 plane of the upper end face of the offset sub, the
{E4254788.DOC;1 }

CA 02344631 2001-04-18
3
1 offset sub being symmetrically internally threaded at its upper end for
2 connection with the mandrel (that is, the threads are coaxial with the
3 upper sub section);
4 ~ the mandrel is externally threaded at each end and has a transverse
bend at a point along its length, close to or at the interface of the offset
6 sub and the adjusting ring, the bend therefore defining upper and lower
7 mandrel sections above and below the bend, each mandrel section
8 having a longitudinal axis of symmetry, the axis of the upper mandrel
9 section being coaxial with the adaptor and the axis of the lower mandrel
section being coaxial with the upper sub section, the mandrel having
11 external splines extending longitudinally thereof above its bend point;
12 ~ the tubular adaptor is straight and has a longitudinal axis which is
13 coaxial with the axis of the mandrel upper section - the adaptor is
14 internally threaded at its lower end for connection with the mandrel and
is threaded at its upper end for connection with the stator of the power
16 section;
17 ~ the tubular adjusting ring is straight and has a canted bottom end face
18 that butts up flush to the upper end face of the offset sub. The adjusting
19 ring further has internal, longitudinally extending splines for engaging
the mandrel splines to lock the ring and mandrel together for rotation
21 while allowing the ring to be moved axially along the mandrel when the
22 ring is not restrained at its upper end - the ring is adapted to turn with
23 the mandrel about the lower axis of the mandrel, which is coaxial with
{ EM 130354.DOC;1 }

a ,
CA 02344631 2004-12-06
4
1 the axis of the upper section of the offset sub. As a result, the lower end
2 face of the ring remains parallel with the upper end face of the offset
3 sub, so as to butt flush therewith, and the upper axis of the mandrel
4 changes orientation relative to the lower axis of the offset sub when
rotated.
6 By the combination of bending the mandrel at about the interface of the ring
7 and the offset sub, bending the offset sub below that interface and canting
the
8 lower end face of the ring and the upper end face of the offset sub, one can
locate
9 the effective bend point of the bent sub assembly beneath the ring (that is,
within
the upper sub section of the offset sub). In addition, by locating the second
bend
11 in the offset sub, this has made it possible to cut the top thread of the
offset sub
12 concentrically, instead of angling it as has been common with prior art
bent sub
13 assemblies. As a result, the section modulus remains constant through the
cross-
14 section of the upper end of the offset sub, thereby avoiding weakening it
as has
been the case in the prior art.
16 Broadly stated, there is provided a bent sub assembly for directional
drilling,
17 comprising an external tubular adaptor having an internally threaded lower
end; an
18 internal tubular mandrel having externally threaded ends and being
transversely
19 bent at a point along its length to define upper and lower mandrel sections
having
angularly offset axes of symmetry, the upper mandrel section being received in
the
21 adaptor lower end and being threadably connected therewith; an external
tubular
22 offset sub transversely bent at a point along its length and at the lower
end of the
{E4254788.DOC;1 }

i r. i ~ il ii r I i .~ I
CA 02344631 2004-12-06
4a
1 mandrel to define upper and lower sub sections having angularly offset axes
of
2 symmetry, the upper sub section
{E4254788.DOC;1 }

CA 02344631 2001-04-18
1 being internally threaded at its upper end and coaxially receiving the lower
2 mandrel section and being threadably connected therewith, the offset sub
having
3 an upper end face perpendicular to the axis of symmetry of the upper sub
section;
4 an external tubular adjusting ring having an axis of symmetry and being
positioned
5 between and abutting the adaptor and the offset sub, the ring being slidably
6 splined with the mandrel, the ring having a lower end face canted at an
angle to
7 the axis of symmetry of the ring; the offset sub upper end face and the ring
lower
8 end face being disposed to butt flush against each other when assembled; the
9 combination, of bending the internal mandrel, bending the offset sub and
canting
the lower end face of the ring, resulting in locating the effective bend point
of the
11 bent sub assembly beneath the ring.
12
13 DESCRIPTION OF THE DRAWINGS
14 Figure 1 is a cross-sectional side view of a bent sub assembly in
accordance with the invention;
16 Figures 2a and 2b are comparative simplified schematic side views of a
17 bent sub in accordance with the present invention and in accordance with
18 conventional design, showing the locations of the bend centers for the two
units;
19 Figure 3 is a simplified side view showing the two bends of the assembly in
conjunction with the canted end faces of the adjusting ring and offset sub;
21 Figure 4 is a cross-sectional side view of the stator housing adaptor of
the
22 bent sub assembly;
{EMI30354.DOC;1 }

CA 02344631 2001-04-18
6
1 Figure 5 is a cross-sectional side view of the bent mandrel of the bent sub
2 assembly;
3 Figure 6 is a side view of the adjusting ring of the bent sub assembly;
4 Figure 7 is another side external view of the adjusting ring;
Figure 8 is a cross-sectional view of the adjusting ring;
6 Figure 9 is a cross-sectional view of the adjusting ring taken along the
line
7 A - - A of Figure 7;
8 Figure 10 is a cross-sectional side view of the offset sub of the bent sub
9 assembly; and
Figure 11 is a fragmentary side view showing the top end of the offset sub.
11
12 DESCRIPTION OF THE PREFERRED EMBODIMENT
13 The bent sub 1 comprises a stator housing adaptor 2, a mandrel 3, an
14 offset sub 4 and an adjusting ring 5. Each of these parts are tubular in
nature.
The adaptor 2 has external and internal threads 6, 7 at its upper and lower
16 ends 8, 9, respectively. It threadably and squarely connects at its upper
end with
17 the stator (not shown) of the downhole motor (also not shown). The adaptor
2 is
18 coaxial with the drilling motor and the drill string above it.
19 The mandrel 3 has external threads 10, 11 at its upper and lower ends 12,
13 respectively. The upper end 12 of the mandrel 3 is threadably connected
with
21 the lower end of the adaptor 2. An O-ring 14 seals the mandrel 3 with the
adaptor
22 2. Between its ends, the mandrel 3 forms splines 15. The mandrel 3 is
{EM130354.DOC;1 }

CA 02344631 2001-04-18
7
1 transversely bent, typically 1.5°, at the bend center 16 to define
upper and lower
2 mandrel sections 40, 41.
3 The offset sub 4 has internal threads 18, 19 at its upper and lower ends 20,
4 21 respectively. The upper end 20 is threadably connected with the mandrel
lower
end 13. The offset sub 4 is bent, typically 1.5°, at the bend center 22
to define
6 upper and lower offset sub sections 42, 43.
7 The mandrel 3 is sealed to the offset sub 4 by the O-ring 24.
8 The adjustment ring 5 is positioned between and abuts the lower end face
9 25 of the adaptor 2 and the upper end face 26 of the offset sub 4. The ring
5
forms internal splines 27 which can slide axially between the splines 15 of
the
11 mandrel 3. The ring 5 is thus capable of being moved axially when the
adaptor 2
12 is displaced upwardly but is locked against rotation with respect to the
mandrel 3
13 when the splines 15, 27 are engaged.
14 The lower end face 28 of the ring 5 is canted 1.5° relative to its
upper end
face 29 or to its axis of symmetry. The upper end face 26 of the offset sub 4
butts
16 flush with the ring lower end face 28.
17 The ring lower end face 28 and the offset sub upper end face 26 are formed
18 to provide alternating dogs 31 and slots 32 (hereinafter referred to as
'dog clutch
19 means'), which engage to lock the ring 5 and offset sub 4 for rotation
together.
Having reference to Figure 3, it will be noted that the resultant
3° bend
21 center 34 of the assembled bent sub 1, provided with 1.5° bends at
the two bend
22 centers 22, 30, is spaced below the ring end face 28.
{ EM 130354.DOC;1 }

CA 02344631 2001-04-18
g
1 To adjust the extent of offset of the axis 35 of the lower offset sub
section
2 43 relative to the axis 36 of the adaptor 2 one can follow the following
procedure:
~ the offset sub 4 is rotationally fixed by applying chain tongs to it;
4 ~ at this stage, the adjusting ring 5 is also rotationally fixed because the
dogs 31 and slots 32 of the dog clutch means are engaged;
~ a second set of chain tongs is applied to the adaptor 2 to back off the
'1 threaded connection between the lower threads 7 of the adaptor 2 and
the upper threads 10 of the mandrel 3 - as the adaptor 2 moves
upwardly as a result, a clearance develops between the adaptor lower
end 9 and the ring upper end face 29;
11 ~ the tongs are then moved from the adaptor 2 to the ring 5 and the ring is
12 lifted so that the dogs 31 and slots 32 of the dog clutch means
13 disengage - however the mandrel and ring splines 15, 27 are still
14 engaged so that the mandrel 3 and ring 5 will turn together;
~ the tongs on the ring are then turned to rotate the ring 5 to a new
16 setting;
17 ~ the ring 5 is then lowered to re-engage the dogs 31 and slots 32 and the
1g adaptor 2 is then turned to lower it to abut the ring 5.
{EM130354.DOC;1 ~

A single figure which represents the drawing illustrating the invention.

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Admin Status

Title Date
Forecasted Issue Date 2005-09-13
(22) Filed 2001-04-18
Examination Requested 2001-04-18
(41) Open to Public Inspection 2002-10-18
(45) Issued 2005-09-13

Abandonment History

Abandonment Date Reason Reinstatement Date
2004-10-19 R30(2) - Failure to Respond 2004-12-06

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $200.00 2001-04-18
Registration of a document - section 124 $100.00 2001-04-18
Application Fee $150.00 2001-04-18
Maintenance Fee - Application - New Act 2 2003-04-22 $100.00 2003-04-16
Maintenance Fee - Application - New Act 3 2004-04-19 $100.00 2004-04-15
Reinstatement - failure to respond to examiners report $200.00 2004-12-06
Maintenance Fee - Application - New Act 4 2005-04-18 $100.00 2005-04-08
Final Fee $300.00 2005-06-27
Maintenance Fee - Patent - New Act 5 2006-04-18 $200.00 2006-03-14
Expired 2019 - Corrective payment/Section 78.6 $350.00 2006-08-25
Maintenance Fee - Patent - New Act 6 2007-04-18 $200.00 2007-04-18
Maintenance Fee - Patent - New Act 7 2008-04-18 $200.00 2008-04-14
Maintenance Fee - Patent - New Act 8 2009-04-20 $200.00 2009-04-14
Maintenance Fee - Patent - New Act 9 2010-04-19 $200.00 2010-03-22
Maintenance Fee - Patent - New Act 10 2011-04-18 $250.00 2011-04-14
Maintenance Fee - Patent - New Act 11 2012-04-18 $250.00 2012-04-05
Maintenance Fee - Patent - New Act 12 2013-04-18 $250.00 2013-04-18
Maintenance Fee - Patent - New Act 13 2014-04-22 $250.00 2014-04-17
Maintenance Fee - Patent - New Act 14 2015-04-20 $250.00 2015-04-17
Maintenance Fee - Patent - New Act 15 2016-04-18 $450.00 2016-04-14
Maintenance Fee - Patent - New Act 16 2017-04-18 $450.00 2017-04-04
Maintenance Fee - Patent - New Act 17 2018-04-18 $450.00 2018-04-17
Maintenance Fee - Patent - New Act 18 2019-04-18 $450.00 2019-04-18
Maintenance Fee - Patent - New Act 19 2020-04-20 $450.00 2019-04-18
Current owners on record shown in alphabetical order.
Current Owners on Record
CAVARE LTD.
Past owners on record shown in alphabetical order.
Past Owners on Record
ROBIN, LAWRENCE E.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Description
Date
(yyyy-mm-dd)
Number of pages Size of Image (KB)
Representative Drawing 2002-02-18 1 8
Description 2003-02-11 6 106
Cover Page 2002-09-27 1 39
Abstract 2001-04-18 1 27
Description 2001-04-18 8 300
Claims 2001-04-18 2 51
Drawings 2001-04-18 7 137
Drawings 2001-11-13 6 104
Description 2004-12-06 10 302
Claims 2004-12-06 2 47
Representative Drawing 2005-08-18 1 10
Cover Page 2005-08-18 2 43
Fees 2005-04-08 1 29
Assignment 2001-04-18 3 113
Prosecution-Amendment 2001-11-13 7 134
Prosecution-Amendment 2003-02-11 3 71
Fees 2003-04-16 1 29
Correspondence 2006-10-04 1 14
Correspondence 2006-10-04 1 20
Prosecution-Amendment 2004-04-19 2 53
Fees 2004-04-15 1 30
Prosecution-Amendment 2004-12-06 15 368
Correspondence 2005-06-27 1 28
Fees 2006-03-14 1 28
Prosecution-Amendment 2006-08-25 2 44
Prosecution-Amendment 2006-10-27 1 27
Correspondence 2006-11-09 1 13
Fees 2007-04-18 1 28
Fees 2008-04-14 1 27
Fees 2009-04-14 1 29
Fees 2010-03-22 1 28
Fees 2011-04-14 1 33
Fees 2012-04-05 1 32
Fees 2013-04-18 1 33
Fees 2014-04-17 1 33
Fees 2018-04-17 1 33
Fees 2019-04-18 1 33