Note: Descriptions are shown in the official language in which they were submitted.
CA 02526153 1996-O1-10
TITLE: WHIPSTOCK ASSEMBLY FOR A SLEEVED CASING
INVENTOR: Robert Joe Coon
FIELD OF '~)~. INVENTION
The field of this invention relates to whipstocks, particularly those that may
be supported by a casing, and more particularly those that can be used in
combina-
tion with a sleeve in the casing.
.
Whipstocks have long been used to divert a milling tool to cut a new
opening through a casing. Typically in these installations, a packer is set in
the
casing which has a lug or some other guide mechanism to orient the whipstock.
The plug or packer is set in the casing and then the whipstock is secured to
the
packer in the appropriate orientation for the new deviated path to be milled
and
ultimately dulled. A milling tool is then used to cut through the casing.
Having
cut through the casing, the milling tool is removed to the surface and
drilling with
the appropriate bit commences.
Various designs of whipstocks and mounting systems therefor are illustrated
in U.S. Patents 2,506,799; 5,154,231; 3,397,746; 5,335,737; 5,341,873; and
5,115,872.
U.S. Patents 5,156,220; 5,090,481; 4,991,654; and 4,880,059 illustrate the
use of sliding sleeves which can be selectively opened to exposed perforations
in
a casing, which can then permit flow into the casing. The Brandel patent
4,991,654 illustrates the use of disintegratable plugs in the openings. U.S.
Patents
4,397,360 and 4,807,704 illustrate the use of whipstocks to create lateral
wellbores
from the main wellbore.
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CA 02526153 1996-O1-10
It should be noted that some casings, particularly in deviated wellbores, may
not be cemented. Casing packers mounted externally to a section or sections of
casing can be used to isolate the casing from the wellbore.
The drawback of the current designs is that a separate mill must be em-
ployed to cut through the casing, which must then be retracted to the surface
so
that a drillbit can be mounted to allow the drilling to continue into the
formation.
The apparatus of the present invention seeks to eliminate the milling step by
providing a casing with a sleeve shiftable between an open and closed position
to
selectively open a window in the casing. The window may be closed during the
cementing operation and may be subsequently opened for forming the deviated
wellbore off of the whipstock. Should it be desired, the sleeve can, anytime
after
the drilling of the deviated wellbore and production therefrom, be fully
closed. The
whipstocks that can be employed with this system can be mounted from the
casing
directly and can also feature a bore therethrough to allow production from pay
zones below the whipstock.
SUMMARY O~ THE INVENTION
A casing is provided with a sealable shifting sleeve. A whipstock is insert
able into the casing and may be supported off of the casing in a predetermined
location so that it is oriented toward an open window in the casing when the
shifting sleeve is selectively moved upwardly. By presenting an open window
for
the whipstock oriented toward the window, a drillbit may be lowered through
the
casing to interact with the whipstock to immediately begin the drilling of the
deviated wellbore. The drillbit cuts through any cement, if present, and into
the
formation. A bore is presented in the whipstock to allow production from pay
zones below the whipstock while it is in place. Should it become necessary,
the
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sliding sleeve may be subsequently closed to isolate the
deviated wellbore which has been drilled with the
whipstock through the open window.
Accordingly, in one aspect of the present invention
there is provided a whipstock mountable in a housing,
comprising:
a housing comprising a shoulder;
said whipstock comprises at least one collet
movable past said shoulder in a first direction but
engaging said shoulder in a reversed second direction;
said collet is connected to a sleeve;
said whipstock further comprises at least one
engagement dog retained against radially outward
movement by said sleeve until said collet moves said
sleeve to release said dog radially for engagement with
said housing.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will now be
described more fully with reference to the accompanying
drawings in which:
Figures lA-D illustrate the casing segment, showing
the window and the sliding sleeve.
Figures 2A-D illustrate the run-in position.
Figure 3 illustrates the lower end of the casing in
section showing the support for the whipstock in the
lift-up position.
Figures 4A-F illustrate the casing of Figures 1 and
2, with the sleeve in the open position and the
whipstock installed in a position ready for drilling.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The body 10 is illustrated in Figures lA-D. A
sleeve 12 is shown in the closed position over a window
14. The window 14 is premade in the body 10 and can
extend as much as approximately 140° circumferentially.
It should be noted that the window 14 is not produced by
a milling tool but is provided in a specially formed
segment of the body 20.
In the preferred embodiment, chevron seals 16 and
18 are, respectively, present at the upper and lower
ends of window 14. Housing 20 retains the chevron seals
16 and 18 to the body 10. Sliding sleeve 12 has a
groove or grooves 26 near its upper end and a groove or
grooves 28 near its lower end for selective engagement
with shifting tool (not shown), of a type well-known in
the art. Use of the shifting tool (not shown) can move
the sleeve 12 from the position shown in Figure 1B,
wherein the window 14 is closed, to the position shown
in Figure 4B, where the window 14 is open. Those
skilled in the art will appreciate that different types
of seals other than a stack of opposed chevron seals can
be used as the sealing assembly 16 or 18 without
departing from the spirit of the invention.
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The whipstock 30 is shown in Figures 4A-F in the set
position. Whipstock 30 has a central bore 32 which
extends to a taper 34 at the upper end 36. Also located
in bore 32 is a groove 38, which is useful in attaching
the whipstock 30 to a running tool so that it can be
positioned in the position shown in Figure 3 from the
surface. Groove 38 may also be used for fishing
operations to assist in removal of a stuck whipstock 30
by merely pulling up. In normal operations, whipstock 30
is removed by pulling upon groove 38. Ring 33 can be
used to facilitate removal of lower segment 41 with upper
segment 39. The whipstock 30 has an upper segment 39 and
a lower segment 41. Lug 67 maintains upper segment 39 in
a specific orientation to lower segment 41 by keyway (not
shown) so that segments 39 and 41 can translate but not
rotate with respect to each other.
Attached to the lower end 40 of whipstock 30 is a
locating apparatus 42. The locating apparatus 42 is
shown in the set position in Figure 4E. In the set
position, the collet 44 has a surface 46 which is shown
hooked on mating surface 48 on the locating apparatus 42.
However, during the run-in position shown in Figures 2A-
D, surface 50 of collet 44 becomes juxtaposed adjacent to
surface 52 of mandrel 54 to clear surface 90 (see Figure
4F). Therefore, during the run-in-position, sleeve 56,
which has an upper end 58, interferes with dog 60,
holding it inwardly against the opposing force of biasing
spring 62. At the same time during run-in, dog 64 rides
on surface 66 of the whipstock 30. Whipstock 30 has a
groove 68 in which sits a split ring 70, which in the
run-in position is juxtaposed against groove 73, with
groove 74 misaligned with groove 68. Ultimately, when
there is latching, as shown in Figure 4E, grooves 68 and
74 come into alignment to allow split ring 70 to expand
and secure the position of locking dog or dogs 64 into a
groove 76 on the body 10. The whipstock 30 has a tapered
surface 78 adjacent to surface 66 so that in the latching
operation, the locking dogs 64 are caromed outwardly along
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surface 78 into groove 76 to secure the engagement of the
whipstock 30 to the body 10 for longitudinal support (see
Figure 4E).
The whipstock 30 has a locating dog 84 which is
formed to engage a locating groove 82 for proper
alignment of the taper 34 with the window 14 in a manner
known in the art. Locating dogs 84 are outwardly biased
by springs 86 to secure and orient the whipstock 30
against rotational forces during the drilling operation
through the window 14. the locating dogs 84 can be
displaced radially inwardly until they come into
alignment with their appropriate grooves in the body 10,
at which point the springs 86 push the dogs 84 outwardly
into their mating grooves. Since the dogs 84 are mounted
to the locating apparatus 42 in a manner that they cannot
rotate with respect to the locating apparatus 42, outward
movement of the locating dogs 84 into their respective
grooves effectively provides a rotational lock.
In running in the tool, the assembly of the
whipstock 30 with the locating apparatus 42 is run into
the body 10 with a suitable running tool. The assembly
is run in a first direction to below the position shown
in Figure 2A-D and then brought up in a second and
opposite direction (see Figure 3). Collet 44 is first
temporarily displaced into groove 88 so that it can clear
surface 90 as the assembly of the whipstock 30 and
locating apparatus 42 is run downwardly in said first
direction into body l0. Once the assembly of the
whipstock 30 and locating apparatus 42 are brought back
up in said second direction, the collets 44 have a
surface 92 which engages tapered surface 94 on body 10.
This results in movement of the collets 44 downwardly
into groove 96 to the position shown in Figure 4D.
Shifting the collets 44 downwardly into groove 96 moves
away the upper end 50 from the
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engagement dogs 60, which allows them to move radially outwardly into groove
98 on body 10.
The dogs 60 have an extending segment I00 which, when la.ched into
groove 98, provides the initial longitudinal support for whipstock 30.
Thereafter,
when weight is set down on said upper segment 39, it moves in said first
direction
with respect to lower segment 41 as taper 78 cams locking dogs 64 and split
ring
70 enters groove 74. In short, the locating apparatus, in combination with the
body
10, provides for proper orientation of the whipstock 30 through the use of
Locating
dogs 84 which fit into a special groove machined into the body 10.
Longitudinal
support for the whipstock 30 is provided by locking dogs 64. Engagement dogs
60 only temporarily support the whipstock 30 until the locking dogs 64 extend
into
the body 10. Rotational support for the whipstock 30 is provided by dogs 84
which go into mating depressions 82 in the body 10, thereby acting as keys
which
lock against torsional forces transmiried by the drilling operation through
the
window 14 to the whipstock 30.
Those skilled in the art will appreciate that by combining the feature of use
of the whipstock 30 along with a body that has a preformed window which can be
selectively covered by a sliding sleeve 12, time and money can be saved for
the
well operator. The reason for this is that in fewer trips into the bore the
complete
sidetrack can be accomplished. This is an improvement over past techniques
where
a milling tool is first used to make the opening in the casing. It is then
removed
and replaced by a drillbit to actually bore the deviated bore. In the present
inven-
tion, the window is opened with a shifting tool and the whipstock 30 is set
with a
running tool in one trip. Drilling a deviated wellbore then commences with a
drillbit in a second trip. A third trip of using the milling tool can be
eliminated.
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A new manner of support of the whipstock has also been described which
allows proper support against rotation and longitudinal movement and proper
orientation, as well as a flow-through feature.
The foregoing disclosure and description of the invention are illustrative and
explanatory thereof, and various changes in the size, shape and materials, as
well
as in the details of the illustrated construction, may be made without
departing
from the spirit of the invention.
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