ADJUSTABLE HOUSING FOR A MUD MOTOR

CARTER REGLABLE DE MOTEUR A BOUE

English Abstract

There is provided an adjustable housing for use with a drill string for controlled directional drilling of a well hole. The housing includes an upper sub and a lower sub each having a first portion extending along a primary axis and a second portion extending along a secondary axis offset from the primary axis by a predetermined angle. The second portions are rotatably mounted together such that the secondary axes of the respective upper and lower subs are coincident. The upper sub is thus rotatable in relation to the lower sub between a bent position wherein the primary axes of the upper and lower subs are misaligned and a parallel position wherein the primary axes of the upper and lower subs are parallel to each other. A locking member is slidably mounted on splines extending radially from the second portion of the upper sub such that the locking member is slidable between an engaged position and disengaged position. In the engaged position the locking member engages teeth on the lower sub such that the upper sub cannot rotate relative to the lower sub. In the disengaged position each sub is rotatable in relation to the other.

French Abstract

Cette invention concerne un carter réglable conçu pour une colonne de forage en vue du forage dévié et contrôlé d'un puits. Le carter comprend un raccord supérieur et un raccord inférieur, chacun ayant une première portion s'étendant le long d'un axe primaire et une deuxième portion s'étendant le long d'un axe secondaire, en retrait de l'axe primaire selon un angle prédéterminé. Les deuxièmes portions sont fixées ensemble de manière articulée, de façon que les axes secondaires des raccords supérieur et inférieur respectifs soient congrus. Le raccord supérieur peut donc être articulé relativement au raccord inférieur, entre une position inclinée où les axes primaires des raccords supérieur et inférieur sont désalignés, et dans une position parallèle selon laquelle les axes primaires des raccords supérieur et inférieur sont parallèles les uns aux autres. Un mécanisme de verrouillage est installé de façon coulissante sur les cannelures s'étendant de façon radiale depuis la deuxième portion du raccord supérieur, de façon que le mécanisme de verrouillage puisse être glissé entre la position engagée et la position désengagée. Dans la position engagée, le mécanisme de verrouillage engage ses dents sur le raccord inférieur de façon que le raccord supérieur ne puisse pas bouger par rapport au raccord inférieur. Dans la position désengagée, chaque raccord peut être articulé l'un par rapport à l'autre.

Claims

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CLAIMS:
1. An adjustable housing for use with a mud motor, the adjustable housing
comprising:
an upper sub comprising a top portion having a primary longitudinal axis, a
bottom
portion having a secondary longitudinal axis offset from the primary
longitudinal axis by a
first predetermined angle, and a first set of splines extending axially along
an outer surface
of the bottom portion;
a lower sub comprising a lower portion having a primary longitudinal axis, a
top
portion having a secondary longitudinal axis offset from the primary
longitudinal axis by a
second predetermined angle, and an engaging face on a top end of the top
portion;
mounting means rotatably mounting the bottom portion of the upper sub on the
top
portion of the lower sub such that the secondary axes are coincident along the
bottom
portion of the upper sub and the upper sub is rotatable relative to the lower
sub;
an annular locking member mounted coaxially to the coincident axes on the
bottom
portion of the upper sub, the locking member having a second set of splines
extending
axially along an inner surface of the locking member and engaging the first
set of splines
coaxially for sliding movement on the bottom portion of the upper sub between
an
engaged position, wherein an end of the locking member engages the engaging
face
uniformly regardless of the relative orientation of the upper and lower subs
to prevent
rotation of the upper sub relative to the lower sub, and a disengaged
position, wherein the
locking member does not engage the engaging face, such that the upper sub is
free to
rotate relative to the lower sub; and
lock securing means for securing the locking member in the engaged position;

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wherein the bottom portion of the upper sub has a reduced diameter for being
received coaxially within the upper portion of the lower sub; and
wherein the mounting means comprises a threaded section having an annular
groove at an end thereof for allowing longitudinal displacement of the upper
sub relative
to the lower sub as the upper sub is rotated relative to the lower sub.
2. The adjustable housing of claim 1 wherein there is provided a first set of
teeth on the end of the locking member and a second set of teeth on the
engaging face of
the lower sub, the first and second sets of teeth being arranged to engage
each other for
locking the subs together in the engaged position, regardless of the relative
orientation of
the upper and lower subs.
3. The adjustable housing of claim 1 or 2 wherein there is provided a threaded
section on a top end of the upper sub for connection to a drill string.
4. The adjustable housing of claim 1, 2 or 3 wherein there is provided a
threaded section on a bottom end of the lower sub for connection to a drill
string.
5. The adjustable housing of claim 1, 2, 3 or 4 wherein there is provided at
least one annular seal mounted about an outer face of the bottom portion of
the upper sub,
the seal being arranged to engage an inner face of the top portion of the
lower sub for
sealing between the subs.
6. The adjustable housing of claim 1, 2, 3, 4 or 5 wherein the lock securing
means comprises a locking nut threadably mounted coaxially to the coincident
secondary

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axes on the bottom portion of the upper sub above the annular locking member
for
uniformly engaging a top end of the annular locking member.
7. The adjustable housing of claim 1, 2, 3, 4, 5 or 6 wherein the first and
second predetermined angles are approximately equal such that the upper sub
may be
rotated relative to the lower sub into a parallel position wherein the primary
longitudinal
axes of the respective upper and lower subs are substantially parallel.
8. An adjustable housing for use with a mud motor comprising:
an upper sub comprising a top portion having a primary longitudinal axis, the
upper sub further comprising a bottom portion having a secondary longitudinal
axis offset
from the primary longitudinal axis by a first predetermined angle;
a lower sub comprising a lower portion having a primary longitudinal axis, the
lower sub further comprising an upper portion having a secondary longitudinal
axis offset
from the primary longitudinal axis by a second predetermined angle, the upper
portion
rotatably engaging the bottom portion to define an area along the housing
where the
secondary axes are coincident;
an annular locking member mounted coaxially to said bottom portion along said
area of coincident axes for sliding movement therealong between an engaged
position with
said lower sub to rotationally fix said upper sub thereto, wherein said
locking member
uniformly engages said lower sub regardless of the relative orientation of
said upper and
lower subs, and a disengaged position wherein said locking member disengages
said lower
sub such that said upper sub is free to rotate relative to said lower sub; and
securing means for securing said locking member in said engaged position;

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wherein the bottom portion of the upper sub has a reduced diameter for being
received coaxially within the upper portion of the lower sub; and
wherein there is provided at least one annular seal mounted about an outer
face of
the bottom portion of the upper sub, the seal being arranged to engage an
inner face of the
top portion of the lower sub for sealing between the subs.
9. The adjustable housing of claim 8, wherein said securing means comprises
a locking nut threadably mounted coaxially to said bottom portion of said
upper sub along
said area of coincident axes for uniformly engaging a top end of said annular
locking
member.
10. The adjustable housing of claim 8 or 9, wherein there is provided a first
set
of teeth on an end of the locking member and a second set of teeth on a top
end of the
upper portion of the lower sub, the first and second sets of teeth being
arranged to engage
each other for locking the subs together in the engaged position, regardless
of the relative
orientation of the upper and lower subs.
11. The adjustable housing of claim 8, 9, or 10 wherein the first and second
predetermined angles are approximately equal such that the upper sub may be
rotated
relative to the lower sub into a parallel position wherein the primary
longitudinal axes of
the respective upper and lower subs are substantially parallel.
12. An adjustable housing for use with a mud motor, the adjustable housing
comprising:

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an upper sub comprising a top portion having a primary longitudinal axis, the
upper sub further comprising a bottom portion having a secondary longitudinal
axis offset
from the primary longitudinal axis by a first predetermined angle;
a lower sub comprising a lower portion having a primary longitudinal axis, the
lower sub further comprising an upper portion having a secondary longitudinal
axis offset
from the primary longitudinal axis by a second predetermined angle, the upper
portion
rotatably engageable with the bottom portion such that the secondary axes are
coincident;
an annular locking member deployed coaxially about the bottom portion of the
upper sub, the locking member configured to displace along the secondary axes
between
first and second locking member positions, the locking member disposed to
rotationally
couple the upper sub and the lower sub when the locking member is in the first
locking
member position, the locking member being disposed to permit the upper
sub to rotate with respect to the lower sub when the locking is in the second
locking
member position;
wherein the bottom portion of the upper sub includes a reduced diameter
configured for receiving in the upper portion of the lower sub; and
further comprising at least one annular seal deployed about an outer face of
the
bottom portion of the upper sub, the seal being configured to engage an inner
face of the
toper portion of the lower sub, the seal being further disposed to provide a
seal between
the upper and lower subs.
13. The adjustable housing of claim 12, further comprising a securing member
deployed coaxially about the bottom portion of the upper sub, the securing
member
configured to displace along the secondary axes between first and second
securing

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member positions, the securing member disposed to secure the locking member in
the first
locking member position when the securing member is in the first securing
member
position, the securing member further disposed to permit the locking member to
displace
between the first and second locking member positions when the securing member
is in
the second securing member position.
14. The adjustable housing of claim 13, wherein the securing member
comprises a locking nut threadably coupled to the bottom portion of the upper
sub coaxial
with the secondary axes.
15. The adjustable housing of claim 12, wherein:
the locking member comprises a first set of teeth on one end thereof;
the upper portion of the lower sub comprises a second set of teeth on a top
end
thereof; and
engagement of the first and second sets of teeth when the locking member is in
the
first locking member position rotationally couples the upper and lower subs.
16. The adjustable housing of claim 12, 13, 14 or 15, wherein the first and
second predetermined angles are substantially equal such that the upper sub
may be
rotated relative to the lower sub into a position in which the primary
longitudinal axes of
the respective upper and lower subs are substantially parallel.

Description

CA 02270109 1999-05-12
ADJUSTABLE HOUSING FOR A MUD MOTOR
FIELD OF THE INVENTION
This invention relates to an adjustable housing for a mud motor and
more particularly to an adjustable housing for incorporating a bend into a
production
string.
BACKGROUND
US Patent 5,048,612 to Bailey et al provides an adjustable bent housing
for controlled directional drilling of well holes. The bent housing comprises
a first sub
rotatably mounted to a second sub for adjustment of an angle therebetween. An
end
portion of the outer surface of the first sub and an end portion of the inner
surface of
the second sub have angular offsets from the central axes of the subs to allow
angular adjustment when one sub is rotated relative to the other. Once the
desired
angle has been set, rotation of the first sub relative to the second sub is
prevented by
an adjusting ring which includes both internal and external splines for
engaging
splines on both first and second subs. The adjusting ring however is axially
aligned
with the first sub and thus engages the splines on the second sub at the
offset angle.
The adjusting ring therefore is not evenly secured across its entire end face
to the
second sub. Machining the complex spline structure and the surfaces at an
offset
angle is a costly and difficult procedure.
SUMMARY
According to the present invention there is provided an adjustable
housing for use with a mud motor, the adjustable housing comprising:
an upper sub comprising a top portion having a primary longitudinal
axis, a bottom portion having a secondary longitudinal axis offset from the
primary
longitudinal axis by a first predetermined angle and a first set of splines
extending
axially along an outer surface of the bottom portion;

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a lower sub comprising a lower portion having a primary longitudinal
axis, a top portion having a secondary longitudinal axis offset from the
primary
longitudinal axis by a second predetermined angle and an engaging face on a
top end
of the top portion perpendicular to the secondary axis of the lower sub;
mounting means rotatably mounting the bottom portion of the upper sub
on the top portion of the lower sub such that the secondary axes are
coincident and
the upper sub is rotatable relative to the lower sub;
an annular locking member mounted coaxially on the bottom portion of
the upper sub, the locking member having a second set of splines extending
axially
along an inner surface of the locking member and engaging the first set of
splines for
sliding movement on the bottom portion of the upper sub between an engaged
positioned wherein an end of the locking member engages the engaging face to
prevent rotation of the upper sub relative to the lower sub and a disengaged
position
wherein the locking member does not engage the engaging face such that the
upper
sub is free to rotate relative to the lower sub; and
lock securing means for securing the locking member in the engaged
position.
The advantage of this arrangement is that the locking member and a
portion of each sub are all coaxial for rotation about the same axis. The
locking
member engages an end engaging face that is perpendicular to that axis and not
offset.
Preferably there is provided a first set of teeth on the end of the locking
member and a second set of teeth on the engaging face of the lower sub, the
first and
second sets of teeth being arranged to engage each other for locking the subs
together in the engaged position, regardless of the relative orientation of
the two subs.
For mounting the adjustable housing in line with a drill string there is

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preferably provided a threaded section on a top end of the upper sub and a
threaded
section on a bottom end of the lower sub.
The lower portion of the upper sub preferably has a reduced diameter
for being received coaxially within the upper portion of the lower sub.
The mounting means may comprise an annular bearing mounted on an
outer face of the bottom portion of the upper sub and an annular groove in an
inner
face of the top portion of the lower sub, the bearing being received in the
groove for
rotatably mounting the upper and lower subs together.
Preferably there is provided at least one annular seal mounted about an
outer face of the bottom portion of the upper sub, the seal being arranged to
engage
an inner face of the top portion of the lower sub for sealing between the
subs.
The lock securing means may comprise a locking nut threadably
mounted coaxially on the lower portion of the upper sub above the annular
locking
member for engaging a top end of the annular locking member.
The first and second predetermined angles may be approximately equal
such that the upper sub may be rotated relative to the lower sub into a
parallel
position wherein the primary longitudinal axes of the respective upper and
lower subs
are substantially parallel.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
Figure 1 is a vertical cross-sectional view of the adjustable housing
connected in line with a drill string showing the adjustable housing in a bent
position
with the locking member engaged.
Figure 2 is a vertical cross sectional view of the adjustable housing in a
bent position with the locking member disengaged.

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Figure 3 is a vertical cross sectional view of the adjustable housing in a
parallel position
with the locking member disengaged.
Figure 4 is a cross sectional view of the adjustable housing along the line 4-
4 of Figure 1.
Figure 5 is a cross sectional view of the adjustable housing along the line 5-
5 of Figure 1.
DETAILED DESCRIPTION
Referring to the accompanying drawings, there is illustrated an adjustable
housing
generally indicated by the reference numeral 10. The adjustable housing 10 is
adjustable between
a bent position as shown in Figure 2 and a parallel position as shown in
Figure 3 such that the
adjustable bent housing may be used with a drill string 12 for controlled
directional drilling.
Referring to Figures 1 through 4, it will be understood that features or
aspects of the
embodiments illustrated may be shown from various views. Where such features
or aspects are
common to particular views, they are labeled using the same reference numeral.
Thus, a feature or
aspect labeled with a particular reference numeral on one view in Figures 1
through 4 may be
described herein with respect to that reference numeral shown on other views.
Referring to Figure 1, the drill string 12 includes a mud motor 14 threadably
connected to
a top end 16 of the adjustable housing and a bearing section 18 threadably
connected at a bottom
end 20 of the adjustable housing. The bearing section 18 rotatably supports a
bit box 22 used for
mounting a drill bit therein. A drive shaft 24 extends through the drill
string. The drive shaft 24
connects between the mud motor 14 and the bit box 22. A pair of constant
velocity joints 26 are
mounted on the drive shaft 24 near respective top and bottom ends of the
adjustable housing to
accommodate the bend in the housing.
The adjustable housing 10 includes an upper sub 30 and a lower sub 32. The
upper sub 30
includes a first upper cylindrical portion 34 having a primary upper
longitudinal axis 36. A
threaded section 38 of reduced diameter extends axially from a top end 39 of
the first upper
cylindrical portion 34 and includes threads on an external surface for
connecting to the drill string
12.
A second upper cylindrical portion 40 of reduced diameter extends from

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a bottom end 41 of the first upper cylindrical portion 34 along a secondary
upper
longitudinal axis 42. The secondary upper longitudinal axis 42 is offset from
the
primary upper longitudinal axis by a predetermined angle. A first set of
splines 44
extends radially outward and axially along an outer face of the sub from a
splined
section 46 of the second upper cylindrical portion 40. A threaded section 48
of the
second upper cylindrical portion 40 above the splined section 46 includes
threads on
external surface thereof. The second upper cylindrical portion 40 includes a
mounting
section 50 below the splined section 46 for mounting the lower sub 32 thereon.
The lower sub 32 includes a first lower cylindrical portion 52 having a
primary lower longitudinal axis 54. A threaded section 56 of reduced diameter
extends axially from a bottom end 57 of the first lower cylindrical portion 52
and
includes threads on an external surface for connecting to the drill string 12.
A second lower cylindrical portion 58 extends from a top end 59 of the
first lower cylindrical portion 52 along a secondary lower longitudinal axis
60. The
secondary lower longitudinal axis 60 is offset from the primary lower
longitudinal axis
by the same predetermined angle as the primary and secondary upper
longitudinal
axes 36 and 42 of the upper sub 30. The second lower cylindrical portion 58 is
arranged to receive the second upper cylindrical portion 40 therein such that
the
secondary upper and lower longitudinal axes 42 and 60 are coincident.
The second upper cylindrical portion 40 includes a plurality of roller
bearings 62 mounted around a periphery of the mounting section 50 to form an
annular bearing. The roller bearings 62 are received in an annular groove 64
around
an inner face 66 of the second lower cylindrical portion 58 for supporting any
axial
loads between the upper and lower subs. A ring seal 69 is also located around
the
inner face 66 and is received in an annular groove in the upper sub for
sealing
between the upper and lower subs.

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The upper sub 30 is thus rotatable relative to the lower sub 32 between
the bent position of Figure 2 and the parallel position of Figure 3. In the
bent position,
the upper and lower primary longitudinal axes 36 and 54 are offset from each
other
such that the adjustable housing 10 may be used for directional drilling. In
the parallel
position, the upper and lower primary longitudinal axes 36 and 54 are parallel
to each
other for drilling straight.
A locking member 68 is mounted coaxially on the splined section of the
second upper cylindrical portion 40. The locking member 68 is in the form of a
collar
having a second set of splines 70 extending radially inwards and axially along
an
inner face of the locking member. The second set of splines 70 is arranged to
engage
the first set of splines such that the locking member 68 is slidable in an
axial direction
along the second upper cylindrical portion and cannot rotate relative to the
second
upper cylindrical portion.
A first set of teeth 72 are mounted around a periphery of a bottom end
74 of the locking member and extend downwards for engaging the lower sub 32.
The
bottom end 74 of the locking member is perpendicular to the secondary axis 60
extending therethrough. A second set of teeth 76 are mounted around a
periphery of
the second lower cylindrical portion 58 and extend upwards from a top end 78
for
engaging the first set of teeth 72. The top end 78 is perpendicular to the
secondary
axis 60 extending therethrough.
The locking member 68 is thus slidable between an engaged position as
shown in Figure 1 and a disengaged position as shown in Figure 2. In the
engaged
position the locking member is adjacent the lower sub such that the first and
second
sets of teeth 72 and 76 are engaged and the upper sub cannot rotate in
relation to the
lower sub. Sliding the locking member upwards will move it into the disengaged
position spaced from the lower sub such that the first and second sets of
teeth 72 and

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76 are disengaged and the upper sub is rotatable in relation to the lower sub.
Rotation of the upper sub in relation to the lower sub will set the offset
angle between
the primary upper and lower longitudinal axes.
A locking nut 80 is mounted coaxially on the threaded section 48 of the
second upper cylindrical portion 40 such that internal threads on the locking
nut mate
with the external threads on the threaded section. The locking nut 80 is thus
rotatable
about the secondary upper longitudinal axis between the engaged position and
the
disengaged position. In the engaged position the locking nut 80 is adjacent
the
locking member 68 for securing the locking member against the lower sub such
that
the first and second sets of teeth are engaged against each other. Rotation of
the
locking nut 80 in a given direction will raise the locking nut into the
disengaged
position. In the disengaged position the locking nut is adjacent the first
upper
cylindrical portion 34 such that the locking member 68 is free to slide
upwards also.
In use the adjustable housing 10 is connected in line with the drill string
12 as shown in Figure 1. If directional drilling is desired the offset angle
between the
primary upper and lower longitudinal axes 36 and 54 is determined and set
before the
adjustable housing is placed in the well hole.
To set the offset angle between the upper and lower subs, the locking
nut is unscrewed such that it is raised into the disengaged position so that
the locking
member may be slid upwards into the disengaged position as well. The upper sub
is
thus rotatable about the lower sub such that the offset angle is adjustable at
any angle
between the minimum when the adjustable housing is in the parallel position
and a
maximum when the upper sub is rotated 180 degrees from the parallel position
in
relation to the lower sub. The locking member and locking nut may then be
secured
in the engaged position such that the adjustable housing may be used in the
well hole
for directional drilling.

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The locking member and locking nut are coaxially mounted with the
subs such that the locking member engages the sub across its entire end face
in the
engaged position regardless of the orientation of the two subs.
With the adjustable housing in the bent position the drill string will drill
into the ground at a slight bend. If straight drilling is desired while the
adjustable
housing is in the bent position, the drill string may be rotated to compensate
for bend.
While one embodiment of the present invention has been described in
the foregoing, it is to be understood that other embodiments are possible
within the
scope of the invention. The invention is to be considered limited solely by
the scope
of the appended claims.

Representative Drawing