Note: Descriptions are shown in the official language in which they were submitted.
2143793
TITLE OF T~ INV~TON:
Surface Adjustable Adjustable Bent Nousing
FIELD OF THE TNVENTION . -~
This invention relates to an adjustable bent
housing for downhole drilling systems.
BA~n~uN~ AND SUMMARY OF TU~ lNV~n~l~........................... ..
United States patent no. 5,125,~63 degcribes
one of the most recent designs for adjustable bent
subs. This design incorporates a single bend in the
device, with the bend occurring between end faces of
a housing and a sliding ring axially slidable on a
mandrel. The housing has an inner shoulder. The
mandrel extends into the housing and is capped with a
locking cap whose end face a~uts the inner shoulder of
the housing. Tightening of a locking ring forces the
locking cap against the inner shoulder of the housing
and the sliding rlng against the end face of the
housing. The faces formed by the end face of the
sliding ring, end face of the housing, inner shoulder
and end face of the locking cap are all offset from a
central axis of the device so that rotation of the
parts in relation to each other results in a bend in
the device.
While this design has proved useful, the
tool is somewhat difficult to adjust and ; ~ er
adjustment may result in an alignment problem that
could lead to failure of the tool. The present
invention provides an il..~L~V. ~nt on this prior art
design that makes proper adjustment easier to achieve.
There is therefore provided in accordance
with one aspect of the invention, an adjustable bent
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housing for use in downhole drilling which includes a
housing, mandrel, ring and locking m~r~n; ~m. The
housing has a housing central axis, a downward facing
end face defining a plane whose normal iY offset from
the housing central axis, and an inner shoulder
parallel to the downward facing end face. The mandrel
has a mandrel central axis, a first end dimensioned to
fit inside the housing and having a downward facing
outer shoulder defining a plane offset from the
mandrel central axis. The ring is axially slidable on
the mandrel, with a ring central axis and an upward
facing end face defining a plane whose normal is
offset from the ring central axis. A locking
mechanism, preferably a mandrel head threaded onto the
mandrel, engages and disengages the upward facing end
face of the ring with the downward facing end face of
the housing and simultaneously engages and disengages
the inner shoulder of the housing with the outer
shoulder of the mandrel.
Keys or like means are preferably used to
control the position of the ring on the mandrel in
selected circumferential positions only. One of the
keys may be differently sized from other keys to
assure proper alignment. Preferably markings on the
ring and housing are used indicate relative degrees of
rotation of the housing in relation to the ring.
BRIEF DESCRIPTION OF THE nR~WINGS
There will now be described preferred
embodiments of the invention, with reference to the
drawings, by way of illustration, in which like
numerals denote like elements and in which:
2~3~3
Fig. lA is a longitudinal section through a
mandrel according to the invention;
Fig. lB is a cross-section through the
mandrel of Fig. lA along the line A-A in Fig. lA;
Fig. 2A is a longitudinal section through a
housing according to the invention;
Fig. 2B is a detail of one end of the
housing of Fig. 2A;
Figs. 3 and 4 show longitudinal sections of
mandrel and housing in two different positions;
Fig. 5A is similar to Fig. 4 with keys
shown;
Fig. 5B is a cross-section showing mandrel,
keys and housing according to the invention along the
line A-A in Fig. 5A;
Figs. 6A and 6B are respectively a cross-
section and longitudinal section of the kick ring;
Figs. 7 and 8 shows mandrel, keys, kick ring
and housing according to the invention in adjustment
and locking positions respectively;
Fig. 9 shows mandrel, mandrel head, keys,
kick ring and housing according to the invention in
locked straight position;
Figs. 10 and 11 show stages of adjustment of
the apparatus of Fig. g;
Fig. 12 shows the apparatus of Fig. 9 during
rotation to an adjusted position;
Figs. 13A, B, C, D, E and F show adjustment
markings for the apparatus of Fig. 9;
Fig. 14 shows the apparatu3 of Fig. 9 in
bent position immediately prior to locking; and
Fig. 15 shows the apparatus of Fig. 9 in
bent locked position.
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n~T~TT-~n DESCRIPTION ~F ~k~KKhv EMBQ3T~'T-~
The mandrel, housing and ring described here
are all tubular at least to the extent required by
drilling methods. Axial in relation to a tubular part
of the device means in the direction of the axis of
the tube. Circumferential means around the
circumference of the tube. Downward is used to define
one axial direction as opposed to the other direction.
However, it should be appreciated that the tool could
be operated upside down, so that downward would then
mean upward. Inner ln relation to a part means
radially inward in relation to that part. Outer in
relation to a part means radially outward in relation
to that part.
The main components of the bent housing
assembly consist of four pieces: a mandrel 20 (Figs.
lA, lB, 3-5B, 7-12 and 14, 15), housing 30 (Figs. 2A,
2B, 3-5B, 7-12, 13A, 13B, 13C, 13D and 13F and 14,
15), kick ring 40 (Figs. 6A-12, 13A, 13B, 13C, 13D,
13~ and 14, 15) and a mandrel head 50 (Figs. 9-12 and
14, 15) forming a locking means for engaging and
disengaging the kick ring, housing and mandrel with
and apart from each other.
Mandrel 20 is a tube with a central axis A
(Fig. lA). The mandrel 20 has an outer shoulder 21 at
one end, with the shoulder 21 facing the downward end
(left side of Fig. lA) of the apparatus. The face 22
of the shoulder 21 defines a plane whose normal is
offset from the central axis A of the mandrel 20. (The
normal of a plane is the line at right angles to the
plane). The degree of offset can vary from assembly to
assembly. For example, if the adjustable assembly
were to be from O degrees to 3 degrees, this face
would have to be machined at an angle of 1~ degrees.
~ 2143793
For an adjustable assembly from 0 degrees to 2
degrees, the face would have to be 1 degree. The face
is machined at 1/2 the desired angle of the assembly.
When this shoulder 21 is finished-machined, it will
have a short side 23 and a long side 24. The exterior
of the shaft, machined parallel to the center axis,
has keyways 25 machined longitudinally in its surface
to accept keys 26 to retain kick ring 40 in a desired
position. The opposite end of the mandrel 20 (away
from the shoulder 21) has a thread 27 or other locking
device machined on it to engage mandrel head 50.
Housing 30 (may be referred to as a kick
housing) is a dimensionally larger tube than the
mandrel 20 80 that the end of the mandrel 20 that
includes the shoulder 21 fits inside at least one end
of the housing 30. The housing 30 has an outer surface
39 parallel to the center axis of the tool, and an
internal thread 31 at one end to adapt the adjustable
assembly to a drill string or drill string assembly
(not shown, but known in the art). A central axis B of
the housing 30 is defined in relation to the outer
surface of the housing. The thread 31 may be external.
The housing 30 has a downward facing end face 32
defining a plane whose normal axis C is offset from
the housing central axis, and an internal shoulder 33
adjacent the downward facing end face 32 is also
machined off the perpendicular of the center axis and
defines a face 38 parallel to the downward facing end
face of the housing 30. In addition, the shoulder 33
as shown in Figs. 2A, 2B, 3, 4 and 5A is parallel to
the face 22 of the outer shoulder 21 of the mandrel
20. A conical internal bore 34 formed by the inner
surface of the housing 30 is machined perpendicular to
the end face 32 and opens away from the face at an
2143793
included angle of at least the same as the total
adjustment angle of the assembly. The end face 32
preferably includes some form of engaging devices 49
to lock it in position with the ring 40, such as
mating grooves, teeth or pro~ectiong. Thig mPr~h~ni~m
i5 not absolutely necessary, but adds assurance of
proper ~ nm~nt and eliminates the possibility of the
housing 30 rotating out of position. When the housing
30 is finish-machined, the housing will have a short
side 35 and a long side 36. On the outer surface of
the housing 30, around the circumference at the end
face 32 end, small windows or marks 37 are milled in
the surface around 90 degrees of the surface (see
Figs. 13A, 13B, 13C, 13D and 13F). The number of
windows 37 will vary with the amount of change in bend
required in the tool. For example, when looking
directly at the end face 32, the first mark would be
on the short side 35 and every other mark would
revolve around the circumference so that the last mark
would be 90 degrees away from the first. ~he maximum
bend of the assembly would be marked in the first
window and O degrees (straight) would be marked in the
last.
In construction (see Fig. 3)r the housing 30
is slid with internal thread 31 first on to the
threaded end 27 oi the mandrel 20. When the housing
30 is slid on all the way, the face of the shoulder 33
of the housing 30 comes in contact with the downward
facing face 22 of the shoulder 21 of the mandrel 20.
At this point in construction, keys 26 can be placed
into the keyways 25 on the mandrel 20 as shown on
Figs. 5A, 5B.
The ring 40 is a tube, with a central axis
and outer surface 41 and inner bore 42 both parallel
214379~
to the central axis. The ring 40 preferably has the
same outside diameter as the housing 30 and iB
dimensioned to fit over and slide on the mandrel 20.
Keyways 43 are machined longitudinally along bore 42
to accept the keys 26 for guiding the ring 40
longitudinally but not circumferentially on the
mandrel 20. One keyway 43a is oversize for proper
alignment. The ring 40 has a downward facing end face
44 machined perpendicular to the center axis and an
upward facing bevelled end face 45 at the opposite end
machined off the perpendicular of the center axis at
the same angle as the outer shoulder 21 of the mandrel
20. In the example shown, the bevelled end face 45 is
formed of a ring 61 as shown such that axial loads are
borne across the end face 45 rather than across the
teeth 49, 49a. The normal of the plane defined by the
end face 45 is thus offset from the ring central axis.
The ring end face 45 preferably has some form of
engaging devices 49, 49a, such as previously described
in relation to the housing, complimentary to the
engaging devices on the end face of the housing 30 to
lock the ring 40 to the housing 30 against rotation
movement when they are pressed together. The engaging
devices 49 add assurance of proper alignment.
Z5 When the ring 40 is finished-machined, it
will have a short side 46 and a long side 47. On the
outer surface 41, around the circumference at the end
face 45, small windows 48 are milled in the surface
around 90 degrees of the surface (see Figs. 13A, 13B,
13C, 13D and 13E). The number of windows (marks) 48
will vary with the amount of change in bend required
in the tool. For example, when looking directly at
the end face 45 of the ring 40, the iirst mark 48 may
be on the short side 46 and every other mark would
2~ ~3793
revolve around the circumference BO that the last mark
would be 90 degrees away from the firat. The maximum
bend of the assembly would be marked in the first
window and 0 degrees (straight~ would be marked in the
last. The placement of the windows is identical on
both the housing 30 and the ring 40.
The ring 40 is slid on to the mandrel 20
from the threaded end 27 of the mandrel 20, bevelled
end face 45 first. For ease of assembly, one keyway
25a may be machined to accept a larger key 26a. This
keyway 25a may be placed in such a way as to line up
the long side 47 of the ring 40 with the short side 23
of the shoulder 21. The keyways 25, 43 on the mandrel
20 and ring 40 respectively are lined up to allow the
oversize key 26a into the oversize keyways 25a, 43a.
When slid on, the bevelled end face 45 of the ring 40
and the end face 32 of the housing 30 butt up to one
another.
The mandrel head 50 is a tube preferably
having an external surface the same outside diameter
as the ring 40 and housing 30, and an external thread
51 at one end to adapt the ad~ustable assembly to a
conventional drill string or drill string assembly
(not shown). The external thread 51 may be internal.
The opposite end of the mandrel head 50 has an
internal thread 52 to adapt it to the mandrel 20. The
mandrel head 50 is screwed onto the mandrel 20 and,
when fully engaged, the end face 53 of the mandrel
head 50 will butt up to the downward facing end face
44 of the ring 40 and lock the adjustable assembly.
Screwing of the mendrel head 50 onto the mandrel 20
forces the ring 40 into engagement with the housing 30
and the shoulder 21 of the mandrel 20 into engagement
with the shoulder 33 of the housing 30. Unscrewing
disengages these respective pArts. Fig. 9 shows the
tool in locked or engaged position with the mandrel
head 50 threaded fully on to the mandrel 20 forming a
straight tool. The corresponding engagement of the
faces 32 and 45 and markings 37 and 48 is shown in
Fig. 13A.
For adjustment, the mandrel head 50 is
screwed partially back off the mandrel 20 to create a
gap F of slightly more than the depth of any
protrusions or other locking feature between the end
faces 32 and 45 of the housing 30 and ring 40
respectively. The backing off of the mandrel head 50
is shown in Fig. 10. The ring 40 is slid back along
the keys 26 until the downward facing end face 44 of
the ring 40 and the end face 53 of the mandrel head
50 come in contact, creating a gap between the ring 40
and the housing 30, as shown in Figs. 11 and 13B. The
housing 30 is rotated around to a predetermined angle
as shown in Fig. 12 and as determined by the markings
37 and 48 (shown in Figs. 13A, 13B, 13C, 13D, 13E and
13F). Once the appropriate markings have been aligned,
the ring 40 is slid against the housing 30 with their
respective faces 45 and 32 abutting each other. An
appropriate angle is achieved when the angle required,
which will appear in one of the windows 37 on the
housing 30, lines up with the same angle marked in a
corresponding window 48 on the ring 40. For example,
when a setting of 3 degrees is required, window 37a on
the housing 30 marked 3.00 will be rotated around to
line up with window 48a on the ring 40 marked 3.00, as
shown in Fig. 13C. With a setting of 0 degrees
(straight), window 37b marked 0 on the housing 30 will
be rotated around to line up with corre8ponding window
48b of the ring 40 marked 0 as shown in Fig. 13A. An
' 2143793
intermediary position (2.12 degrees~ is shown in Fig.
13D.
After the desired setting is achieved with
the ring 40 slid back to its original position,
engaging any locking devices on the facing end faces
32 and 45 and abutting these faces 32 and 45 against
each other, the mandrel head 50 is then screwed back
to butt against the end face 44 of the ring 40, which
will lock the assembly in position and ready it for
use as shown in Fig. 15.
A person skilled in the art could make
immaterial modifications to the invention described
and claimed in this patent without departing from the
essence of the invention.
