U.S. patent application number 09/883046 was filed with the patent office on 2002-02-28 for deviated borehole drilling assembly.
Invention is credited to Begg, Stephen M..
Application Number | 20020023747 09/883046 |
Document ID | / |
Family ID | 27170676 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020023747 |
Kind Code |
A1 |
Begg, Stephen M. |
February 28, 2002 |
Deviated borehole drilling assembly
Abstract
An assembly for formation and completion of deviated wellbores
is disclosed which includes a toolguide and a casing section which
can be used together or separately. The toolguide includes a lower
orienting section and a whipstock having a sloping face, commonly
known as the directional portion of a whipstock. The toolguide is
coated with a material such as epoxy or polyurethane to provide a
repairable surface and one which can be removed to facilitate
removal of the toolguide from the well bore. The lower orienting
section has a latch which extends radially outwardly from the
section and can be locked in the outwardly biased position. The
casing section of the present invention includes a sleeve which can
be moved between a first position in which access to the window
opening of casing section is not affected and a second position in
which the main casing is sealed from the liner section of a
deviated wellbore to provide a hydraulic seal against passage of
fluids from outside the casing of the wellbore into the main
casing.
Inventors: |
Begg, Stephen M.; (Edmonton,
CA) |
Correspondence
Address: |
Schlumberger Technology Corporation
Schlumberger Reservoir Completions
14910 Airline Road
P.O. Box 1590
Rosharon
TX
77583-1590
US
|
Family ID: |
27170676 |
Appl. No.: |
09/883046 |
Filed: |
June 15, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09883046 |
Jun 15, 2001 |
|
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09305775 |
Apr 16, 1999 |
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Current U.S.
Class: |
166/117.5 ;
166/52 |
Current CPC
Class: |
E21B 47/09 20130101;
E21B 23/02 20130101; E21B 41/0042 20130101; E21B 7/061 20130101;
E21B 34/14 20130101; E21B 23/04 20130101; E21B 43/10 20130101; E21B
23/12 20200501; Y10S 166/902 20130101 |
Class at
Publication: |
166/117.5 ;
166/52 |
International
Class: |
E21B 007/06; E21B
023/03 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 1998 |
CA |
2,236,047 |
Aug 18, 1998 |
CA |
2,245,342 |
Claims
The embodiments of the invention in which an exclusive property
privilege is claimed are defined as follows:
1. A whipstock for use in a subterranean well, comprising: a main
body having an outer surface; a sloping face portion formed on the
main body and having a slope angle; and an extension formed on the
main body about the sloping face such that the diameter of the
extension is greater than the diameter of the main body.
2. The whipstock of claim 1, wherein the extension about the
sloping face portion forms an effective diameter which is
substantially equal to the drift diameter of the casing into which
it is to be used.
3. The whipstock of claim 1, further comprising: centralizers
extending out from the main body; and the effective diameter of the
whipstock at the centralizers being substantially equal to the
effective diameter of the whipstock at the extension.
4. The whipstock of claim 1, wherein: the body includes an upper
end; and a dove-tail slot and a second slot are formed on the upper
end.
5. The whipstock of claim 1, wherein: the body include a lower end;
and the lower end is connected to an orienting tool.
6. The whipstock of claim 1, further comprising a coating applied
over at least a portion of the whipstock.
7. The whipstock of claim 6, wherein the coating is polymeric
material.
8. The whipstock of claim 1, further comprising: centralizers
extending out from the main body; and a coating applied over at
least a portion of the whipstock to be flush with an outer contact
surface of the centralizers.
9. The whipstock of claim 8, wherein the effective diameter of the
whipstock at an outer surface of the coating is substantially the
same as the effective diameter of the whipstock at the
centralizers.
10. The whipstock of claim 9, wherein the effective diameter of the
whipstock at the centralizers is substantially equal to the drift
diameter of the casing into which it is used.
Description
[0001] This application is a continuation of U.S. application Ser.
No. 09/305,775 filed on Apr. 16, 1999, which is a
continuation-in-part of U.S. application Ser. No. 08/923,945 filed
on Sep. 5, 1997, now U.S. Pat. No. 6,012,516. The '775 Application
also claims the benefit of Canadian Patent Application No.
2,236,047, filed on Apr. 27, 1998, and Canadian Patent Application
No. 2,245,342, filed on Aug. 18, 1998.
FIELD OF THE INVENTION
[0002] The present invention is directed to a borehole drilling
assembly and in particular to an assembly for drilling and
completing deviated boreholes.
BACKGROUND OF THE INVENTION
[0003] Deviated boreholes are drilled using whipstock assemblies. A
whipstock is a device which can be secured in the casing of a well
and which has a tapered, sloping upper surface that acts to guide
well bore tools along the tapered surface and in a selected
direction away from the straight course of the well bore.
[0004] To facilitate the use of a whipstock, a section of casing is
used which has premilled window openings through which deviated
well bores can be drilled. The whipstock can be positioned relative
to the window using a landing system which comprises a plurality of
stacked spacers mounted on a fixed mounting device at the bottom of
the casing and defining at the top thereof a whipstock retaining
receptacle, or by use of a latch between the whipstock and the
casing. A stacked landing system can cause difficulty in aligning
the whipstock with the window opening as the distance between the
mounting device and the window increases. The whipstock may also
turn during the drilling or setting processes resulting in the
deviated well bore being directed incorrectly and/or the well bore
tools being stuck in the wellbore. Sometimes a latch system is used
to overcome some of these disadvantages. However, the latch can
sometimes disengage between the whipstock and the casing, allowing
the whipstock to turn or move down in the casing.
[0005] After the deviated wellbore is drilled, it can be left
uncompleted or completed in any suitable way. To seal the deviated
wellbore hydraulically from the main casing, a liner can be
installed and cement can be pumped behind the liner. This is
expensive and often creates obstructions in the main casing which
complicates removal and run of the tools.
[0006] When the tools are used in horizontal primary bores, new
problems arise. Running and retrieval tools which are useful for
vertical tool manipulation are not always useful in horizontal
applications.
SUMMARY OF THE INVENTION
[0007] An assembly for drilling and/or completing a deviated
wellbore has been invented. In one aspect the assembly includes a
toolguide which can be positioned relative to a window opening in a
casing section and releasably locked in position. The toolguide or
portions thereof can have applied thereto a coating which prevents
damage to the metal components of the toolguide and facilitates
removal of the toolguide from the wellbore after use.
[0008] A tool guide for creating deviated borehole branches from a
wellbore includes a whipstock including a sloping face portion and
a lower orienting section, including at least one latch biased
radially outwardly from the orienting section and positioned in a
known orientation relative to the sloping face portion and a latch
locking means to releasably lock the latch in an extended position,
the latch locking means being actuated to lock the latch by torsion
of the mandrel within the lower orienting section.
[0009] Each latch of the orienting section is selected to fit
within and lock into its own latch receiving slot formed in the
casing. When the latch of the orienting section is locked into the
latch receiving slot the toolguide will be maintained in position
in the casing. Preferably, the casing includes at least one
premilled window opening positioned in known relation relative to
the latch receiving slot. Preferably, a removable liner can be
positioned in the casing to close the window opening temporarily
and to cover the latch receiving slot.
[0010] The orienting section can be releasably connected to the
whipstock. Such connection is preferably by connectors such as, for
example, shear pins to the whipstock so that these parts can be
installed together into the casing. Preferably, the connectors are
selected such that the sections can be separated by an application
of force sufficient to overcome the strength of the connectors.
This permits the whipstock and the lower section to be separated
and removed separately should one part become stuck in the
casing.
[0011] The sections are movable relative to one another and means
are provided to translate such movement to actuate such means as a
seal.
[0012] Preferably, the lower orienting section includes a mandrel
engaged slidably and rotatably within an outer housing. The mandrel
is releasably connected to the whipstock and moveable with the
whipstock. Preferably, the latch locking means is an extension of
the mandrel. The extension can be formed to fit behind the latch to
lock it in the outwardly biased position.
[0013] Another toolguide for creating borehole branches from a
wellbore, the toolguide having a longitudinal axis and comprising a
whipstock including a sloping face portion, a lower orienting
section, the whipstock and the lower orienting section being
connected and moveable relative to each other along the
longitudinal axis of the toolguide, and an annular sealing means
mounted below the whipstock, the annular sealing means being
actuatable to expand and retract upon movement of the whipstock and
the lower orienting section relative to one another.
[0014] The whipstock is attached to a central mandrel of the lower
orienting section. The central mandrel is engaged slidably and
rotatably within an outer housing of the lower orienting section.
The outer housing carries the annular sealing means which is
actuatable to expand or retract by movement of the mandrel within
the outer housing. Preferably, the outer housing includes a first
section and a second section and disposed therebetween the annular
sealing means. The first section is moveable toward the second
section to compress the annular sealing means therebetween and
cause it to expand outwardly. In this embodiment, preferably the
mandrel has a shoulder positioned thereon to abut against the first
section and limit the movement of the mandrel into the outer
housing. Abutment of the shoulder against the first section causes
the first section of the housing to be driven it towards the second
section and the annular sealing means to be compressed and expanded
outwardly.
[0015] Previous orienting tools were difficult to use because it
was necessary to run the tool to a known depth and then search
around for the position of the slot for accepting the latch on the
tool. Because the latches of some orienting tools have to be biased
outwardly on the trip down into the well, it has been difficult to
use the orienting tools in wells, for example, having more than one
lateral window and therefore more than one orienting slot for
accepting the latch of the tool. To the problem of having the latch
lock into the incorrect slot, where multiple slots are present, it
has been necessary to shape the slots in the casing such that they
will only accept one form of latch. This solution presents
logistical problems, however, and limits the number of slots which
can reasonably be positioned in the casing.
[0016] Thus, in accordance with one broad aspect of the present
invention, there is provided an orienting tool for positioning in a
well bore casing having a profile positioned therealong, the tool
comprising: a body; at least one member mounted on the tool body
and biased outwardly, at a selected pressure, therefrom, the
selected pressure being great enough to permit determination of
when the at least one member has moved past the profile but not
being so great as to prevent the at least one member from moving
past the profile using normal force.
[0017] The at least one member can be a spring loaded dog or an arm
such as, for example, a part of a collet, a collar locator or any
other means. In preferred embodiment, the at least one member is
part of a ring of dogs mounted about a circumference of the tool
body and biased outwardly therefrom. The at least one member
preferably operates to position the tool at a selected pressure of
20,000 to 30,000 psi. At this pressure, when the member passes a
profile, there will be a indicative overpull or decrease in drill
string weight.
[0018] The at least one member can be biased outwardly by any
desired means such as, for example, springs. In a preferred
embodiment, the biasing means is selected to exert increased
pressure as the depth of the tool is increased. This biasing means
is preferred as it provides that less force is required to move the
tool through the casing at shallower depths but requires greater
force to be moved through the casing when it is at greater depths
and, therefore, when there is greater available drill string weight
to act on the tool. One such biasing means is sensitive to
hydrostatic pressure and applies a pressure to the at least one
member which increases with an increase in hydrostatic pressure of
the fluids about the tool. It may be necessary to set an upper
limit for the selected pressure applied to the at least one
member.
[0019] The profile and the at least one member are preferably
correspondingly positioned so that the at least one member will be
affected by the profile regardless of the rotational orientation of
the tool within the casing. To avoid forming a protrusion which
extends inwardly from the casing inner surface and reduces the ID
of the casing, preferably the profile is a groove sized to accept
the at least one member therein. In a preferred embodiment, the
groove is a radial groove extending about the ID of the casing.
[0020] There can be more than one profile along a length of casing.
Where more than one profile is present along the casing, the at
least one member will be affected by each profile in a similar
manner. Preferably, the profiles are non-selective. The specific
profile which is affecting the member can be determined using tool
depth information, the measurement of which is well known in the
art.
[0021] Where it is desired, in addition to positioning the tool at
a selected orientation along the casing, to position the tool at a
selected rotational orientation within the well, the tool can
further comprise a latch for fitting into a slot positioned at a
selected rotational position about the center axis of the casing.
The tool is selected to provide for rotation of at least the
portion of the tool carrying the latch to permit the latch to be
located in its slot. In one embodiment, the tool body includes a
first part carrying the at least one member, a second part carrying
the latch and a joint positioned therebetween for permitting the
second part to rotate relative to the first part and preferably
also to move out of axial alignment with the first part.
[0022] The orienting sections according to the present invention
can be used to orient whipstocks as well as other tools such as,
for example, retrieval tools, sleeve shifting tools and lateral
completion tools.
[0023] A whipstock for use in creating wellbore branches from a
well bore can have a main body formed of a first material of
reduced diameter to facilitate washover or engagement by die
collars or overshots. The main body has extending out therefrom
centralizers such as stand off rings or extensions the main body.
Sometimes a coating material is disposed at least over a portion of
the main body, the coating material being softer than the first
material and being resistant to oil and gas.
[0024] In a whipstock having a main body of reduced diameter
relative to centralizers formed thereon, it has been found that the
width of the sloping face portion is greatly reduced. This reduces
the surface area which is available to guide the drill bit or mill
off the whipstock face and the mill or drill bit tends to roll off
the sloping face portion in the direction of rotation of the
drill.
[0025] To prevent roll off and to centralize and stabilize the
upper tapered end of the whipstock, while continuing to facilitate
washover procedures, a whipstock is provided including a main body
having an outer surface, a sloping face portion formed on the main
body and having a slope angle and an extension formed on the main
body about the sloping face such that the diameter of the extension
is greater than the diameter of the main body.
[0026] Preferably, the extension about the sloping face portion
forms an effective diameter which is substantially equal to the
drift diameter of the casing into which it is to be used. The
extension preferably conforms to the slope angle of the sloping
face portion and, where the sloping face portion has a curvature,
follows and continues the curvature of the sloping face
portion.
[0027] The whipstock can include centralizers extending out from
the main body. Preferably, the effective diameter of the whipstock
at the centralizers is substantially equal to the effective
diameter of the whipstock at the extensions.
[0028] In one embodiment, the main body has applied thereto a
coating, for example of polymeric material. The coating material
can be applied against the extension and the centralizers, if
any.
[0029] Running and retrieving tools are required for moving the
tools through the well bore. Previous running tools for whipstocks
used shear bolts for attachment between the running tool and the
whipstock. These shear bolts are prone to shearing prematurely if
the whipstock is bumped at surface while entering the will or sue
to running the assembly through a tight area in the casing. The
shear bolt may also shear prematurely if the assembly is
rotated.
[0030] A new tool has been invented which is positively latchable
to the whipstock in a manner that allows forces to be applied
upwardly or downwardly as well as rotationally without risk of
prematurely releasing the whipstock. At the desired time of
release, hydraulic pressure is applied to the tool to unlatch it
from the whipstock.
[0031] In accordance with a broad aspect of the invention,
therefore, there is provided a running/retrieval tool for moving a
well tool through a well bore casing, the running/retrieval tool
comprising: a body; a latch for releasably engaging the well tool
and being driven to move between a retracted position recessed in
the body and an extended position in which a portion of the latch
extends from the body; and a guide selected to act against the well
tool to guide the latch into engagement with the well tool.
[0032] The latch can be driven between the retracted position and
the extended position by any desired means. Preferably, the drive
means for the latch can be controlled from surface and can be, for
example, a hydraulic system.
[0033] The guide is formed on the tool and can be selected to
engage with the well tool in such a way as to transmit rotational
energy to the well tool. A key can be provided on the tool to
assist in the location of the tool relative to a well tool to be
retrieved. In a preferred embodiment, an outwardly biased key is
provided which is engage able into an orienting slot formed on the
casing section adjacent the mounting position of the well tool to
be used with the running retrieval tool.
[0034] In another embodiment, the running/retrieval tool according
to the present invention includes a outwardly extendable and
retractable key useful for applying force against the casing in
which the tool is positioned to urge it toward one side of the
casing. The key can be extendable by a hydraulic system.
[0035] A casing section for a deviated wellbore junction comprises
a cylindrical casing tube having a central axis and a window
opening formed therein. A sleeve having an opening therein is
mounted relative to the casing tube to move between a first
position in which the opening of the sleeve is aligned with the
window opening of the casing tube and a second position in which
the opening of the sleeve is not aligned with the window opening of
the casing tube.
[0036] Another casing section for a deviated wellbore junction
includes a casing tube having a central axis and a window opening
formed therein. A sleeve having a first opening and a second
opening therein is mounted relative to the casing tube to move
between a first position in which the first opening of the sleeve
is aligned with the window opening of the casing tube and a second
position in which the second opening of the sleeve is aligned with
the window opening of the casing tube.
[0037] Preferably, sealing means are disposed between the casing
tube and the sleeve. These sealing means are preferably selected to
effect a hydraulic seal between the parts. In one embodiment, the
sealing means are formed of deformable materials such as rubber or
plastic and is disposed around the opening of the sleeve and along
the top and bottom thereof.
[0038] In a preferred embodiment, the sleeve has formed
therethrough two openings. The first opening is sized to allow
access to the window opening of the casing section by deviated
borehole tools and the second opening is smaller than the first
opening.
[0039] In one embodiment, the sleeve is disposed within the casing
tube in a counterbore formed therein such that the inner diameter
of the sleeve is greater than or substantially equal to the inner
diameter of the casing away from the position of the sleeve.
[0040] Preferably, the window of the casing is formed to accept a
flange of a junction fitting such as, for example, a tieback hanger
of a branched wellbore. In a preferred embodiment, the sleeve is
selected to seal against the flange of the fitting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] A further, detailed, description of the invention, briefly
described above, will follow by reference to the following drawings
of specific embodiments of the invention. These drawings depict
only typical embodiments of the invention and are therefore not to
be considered limiting of its scope. In the drawings:
[0042] FIG. 1 is a schematic representation of an embodiment of an
assembly according to the present invention, the assembly being
positioned in a wellbore;
[0043] FIG. 2 is a view showing the orientation of FIGS. 2a and
2b.
[0044] FIGS. 2a and 2b are a longitudinal section along a casing
section for a deviated wellbore junction useful in the present
invention;
[0045] FIG. 3A is a view showing the orientation of FIGS. 3A-a and
3A-b;
[0046] FIGS. 3A-a and 3A-b are a front elevation view, partly
cutaway, of a whipstock of a toolguide according to the present
invention;
[0047] FIG. 3B is a view showing the orientation of FIGS. 3B-a and
3B-b;
[0048] FIGS. 3B-a and 3B-b are a section along line 3B-3B of FIG.
3A;
[0049] FIG. 4A is a view showing the orientation of FIGS. 4A-a and
4A-b;
[0050] FIGS. 4A-a and 4A-b are a front elevation view, partly
cutaway, of a whipstock of another toolguide;
[0051] FIG. 4B is a view showing the orientation of FIGS. 4B-a and
4B-b;
[0052] FIGS. 4B-a and 4B-b are a section along line 4B-4B of FIG.
4A;
[0053] FIGS. 4C and 4D are sectional views along line 4C-4C and
4D-4D, respectively, of FIG. 4B;
[0054] FIG. 4E is a bottom end view of FIG. 4A;
[0055] FIG. 4F is a top end view of FIG. 4A;
[0056] FIG. 5A is a front elevation view of a lower section of a
toolguide according to the present invention, partly in section and
in un-compressed configuration;
[0057] FIG. 5B is a front elevation view of the toolguide of FIG.
5A in compressed configuration;
[0058] FIG. 5C is a section along line 5C-5C of FIG. 5A;
[0059] FIG. 6A is a view showing the orientation of FIGS. 6Aa and
6Ab;
[0060] FIGS. 6Aa and 6Ab are longitudinal sections along another
lower section of a toolguide in a set configuration;
[0061] FIG. 6B is a view showing the orientation of FIGS. 6Ba and
6Bb;
[0062] FIGS. 6Ba and 6Bb are longitudinal sections along another
lower section of a toolguide;
[0063] FIG. 7 is a view showing the orientation of FIGS. 7A to
7C;
[0064] FIGS. 7A to 7C are longitudinal sections along a casing
section for a deviated wellbore junction;
[0065] FIG. 8 is a view showing the orientation of FIGS. 13a and
13b;
[0066] FIGS. 8a and 8b are longitudinal sectional views along a
running/retrieving tool;
[0067] FIG. 9 is a longitudinal section along another casing
section for a deviated wellbore junction according to the present
invention;
[0068] FIG. 10 is a rear plan view of a sleeve according to the
present invention in flattened configuration;
[0069] FIG. 11A is a sectional view through a deviated wellbore
junction using a casing section according to the present
invention;
[0070] FIG. 11B is a front elevation view of a tieback hanger;
[0071] FIG. 11C is a front elevation view of a tieback hanger;
[0072] FIG. 12 is a front elevation view of another sleeve
according to the present invention in flattened configuration;
[0073] FIG. 13 is a view showing the orientation of FIGS. 13a and
13b;
[0074] FIGS. 13a and 13b are elevation views of a casing section
including a window opening;
[0075] FIG. 14 is a longitudinal sectional view along a liner
positioning tool;
[0076] FIG. 15 is schematic representation of a system for
imparting rotational force on a drill pipe;
[0077] FIG. 16A is a longitudinal sectional view along a sleeve
shifting tool according to the present invention;
[0078] FIG. 16B is front elevation view of a portion of the sleeve
shifting tool of FIG. 16A showing the sleeve engaging slips;
[0079] FIG. 17 is an elevation view of a casing section including a
window opening according to the present invention;
[0080] FIG. 17A is a sectional view along line A-A of FIG. 17;
[0081] FIG. 17B is a sectional view along line B-B of FIG. 17;
[0082] FIG. 17C is an enlarged view of an edge of the window
opening, as noted in FIG. 17A;
[0083] FIG. 18 is a front elevation view of a tieback hanger in
accordance with another aspect of the present invention;
[0084] FIG. 18A is a sectional view along line A-A of FIG. 18
showing the lower setting tab;
[0085] FIG. 18B is a sectional view along line B-B of FIG. 18
showing the mid setting flanges;
[0086] FIG. 18C is a sectional view along line C-C of FIG. 18
showing the upper setting tab;
[0087] FIG. 19A is a sectional view through a casing section
according to FIG. 17 having a tieback hanger according to FIG. 18
therein with the upper setting tab in unengaged position; and
[0088] FIG. 19B is a sectional view as in FIG. 19A with the upper
setting tab in engaged position in the window of the casing
section.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0089] For the purposes of clarity, in the Figures only reference
numerals of the main components are indicated and like reference
numerals relate to like components.
[0090] Referring to FIG. 1, there is a shown a tubular wellbore
casing 2 for installation in a primary wellbore 4 drilled through a
formation. Primary wellbore 4 can be a main wellbore directly
opening to surface or a lateral wellbore drilled from a main
wellbore. Primary wellbore can range between a vertical and a
horizontal orientation. Casing 2 includes upper and lower sections
of production casing 6 and secured therebetween a casing section 8
for use in deviated wellbore junctions. The deviated wellbores
branch from wellbore 4.
[0091] Casing sections 6 and 8 are connected by standard connectors
9 or any other suitable means. A float collar 10 is provided at the
lower end of casing 2 which allows fluids to flow out of the casing
but prevents flow of fluid and debris back into wellbore casing 2.
Any similar one way valve can be used in the place of float collar
10. By a completion procedure, cement 11 is disposed in the casing
annulus.
[0092] Casing section 8 includes a window in the form of an
elongated opening 12 extending in the longitudinal direction of
casing 8. In use, opening 12 is oriented toward the desired
direction of a deviated wellbore to be drilled, shown in phantom at
14. The window is sized and shaped with reference to the desired
diameter and azimuth of the deviated wellbore to be drilled and the
diameter of the casing, as is known in the art.
[0093] Casing section 8 further has formed therein a latch
receiving slot 16a at a selected orientation relative to window
opening 12. The latch receiving slot can be oriented at any point
around the interior circumference of the casing section, so long as
its position is known with respect to the window opening.
Preferably, latch receiving slot 16a is aligned with the
longitudinal axis of window 12, as shown, or is directly opposite
window opening 12.
[0094] A toolguide 18 is installed in casing 2 with its latch 20
extending into slot 16a. Toolguide 18 includes a lower orienting
section 22, also called a monopositioning tool, from which latch 20
is biased radially outwardly, and a whipstock 24 having a sloping
face portion 26. Sections 22 and 24 are connected so that they are
not free to rotate relative to each other, whereby face portion 26
is maintained in a fixed and known orientation relative to latch
20. In a preferred embodiment, as shown, latch 20 is aligned at the
bottom of sloping face portion 26, so that the surface of the
sloping face portion will be aligned opposite window opening 12,
when latch 20 is in slot 16a.
[0095] An annular expandable seal 28 is disposed on toolguide 18
below sloping face portion 26. The seal 28 when expanded, acts to
prevent debris and fluids from passing down the wellbore. Seal 28
is, therefore, selected to have an outer diameter, when expanded,
which is greater than the inner diameter of the casing in which it
is to be used.
[0096] Toolguide 18 is placed in casing 2 by use of a running tool
30 which releasably locks onto whipstock 24 and is shown in this
drawing still attached to the whipstock. Running tool 30 is
connected to a drill pipe 32.
[0097] To remove the toolguide from the wellbore, a retrieving tool
can be used. FIG. 8, show a tool that is useful for both running
and retrieving operations.
[0098] To prepare for the drilling of a deviated borehole, such as
that shown at 14, the wellbore casing 2 is installed and completed.
FIG. 2 shows apparatus useful for permitting completion of the well
while preserving features used in the invention. Casing section 8
is milled to include a window opening 12 and a latch receiving slot
16a. Preferably, a slot 17 (FIG. 2) for alignment of retrieval
tools is also milled out in casing section 8. Preferably, window
opening 12 and latch receiving slot 16a are aligned along the
casing.
[0099] A liner 34 is positioned in casing 8 and seals 36a and 36b
are provided between liner 34 and casing 8. A float collar 38 and
an orienting subassembly 39 are attached above liner 34. Float
collar 38 and orienting subassembly 39 can be positioned, as shown,
or can be positioned further up the casing provided orienting
subassembly is in a known configuration relative to window opining
12. Preferably, a removable filler 41 which is selected to
withstand high downhole hydrostatic pressures, such as high density
polyurethane or cement, is inserted between casing 8 and liner 34
between seals 36b to fill window opening 12 and the casing section
8 is wrapped in a rigid material 40, such as fibre glass or
composite tape, to cover at least opening 12.
[0100] Preferably, slots 16a and 17 are filled with liquid or
easily removable filling materials such as grease and/or foam to
prevent materials from entering into the slots and the remainder of
spaces 43, defined between casing 8, liner 34 and seals 36a, 36b,
are filled with cement. To further prevent entry of materials into
slots 16a, 17, caps 44 are welded onto the outer surface of casing
8 over the slots.
[0101] Casing 8, including the parts as noted hereinbefore, is
connected to casing sections 6 to form casing string 2 and float
collar 10 is attached. Casing string 2 is lowered into wellbore 4.
The casing string is rotated until window opening 12 is oriented in
the direction in which it is desired that the deviated wellbore 14
should extend. Suitable methods are well known in the oil and gas
industry for orienting downhole tools. As an example, a surface
reading gyro, a mule shoe or other suitable means can be used.
[0102] The cased wellbore is completed by forcing cement through
the casing string and into the annulus between the casing and the
wellbore. During completion, the cement is forced through float
collar 38 and liner 34 but is prevented from moving behind liner 34
by seals 36a and the cement and fillers in spaces 43. As the cement
fills the casing annulus, it is prevented from entering slot 16a by
cap 44 and is prevented from entering window opening 12 by the
filler 41 and rigid materials 40. The cement is allowed time to
set.
[0103] After completion, a drill (not shown) of a diameter selected
to be approximately equal to the inner diameter of the casing is
run into the well to remove cement from the casing bore. The drill
will also drill out liner 34, seals 36a, 36b, float collar 38 and
cement in spaces 43. Thus, liner 34 is formed of a material such
as, for example, aluminum, fibre glass, or carbon fibre-containing
composite, which can be removed by drilling or by any other method
without having to retrieve to surface. Where aluminum is used in
the wellbore, preferably any aluminum surfaces which are exposed
and will be contacted by the cement used in the completion
operation, are coated with a suitable material, such as rubber
cement, to improve the bond of the cement to the aluminum.
[0104] The casing is then ready for production or for drilling
deviated wellbores. Where deviated wellbores are to be drilled a
toolguide 18 will be run in and oriented in the casing as shown in
FIG. 1.
[0105] In FIGS. 3A and 3B and FIGS. 4A to 4F, two embodiments of a
whipstock are shown. Referring to FIGS. 3A and 3B, a whipstock 24
tapers toward its upper end to form a sloping, ramped face portion
26 which is formed to direct any tool pushed along it laterally
outwardly at a selected angle. The face portion is machined to have
a selected slope x or range of slopes with respect to long axis 52
of the section depending on the build radius desired for the
deviated wellbore. As an example, when x is 4/, the build radius
will be approximately 15.degree./30 meters drilled. Preferably,
sloping face portion 26 is formed to be concave along its
width.
[0106] An entry guide 49 is welded at the top of face portion 26.
Entry guide 49 assists in centralization and tool retrieval and
need only be used, as desired. A bore 50 extends a selected
distance through the whipstock parallel to its central axis 52.
Bore 50 is formed to engage a fishing spear device and provides one
means of retrieving the toolguide from the wellbore. Extending back
from face portion are slots 53 formed to accept and retain a
retrieval tool having corresponding sized and spaced hooks thereon.
Also formed on face portion 26 are apertures 54 formed to accept
shear pins (not shown) for attachment to running tool 30 (FIG.
1).
[0107] Centralizers 56 are spaced about the whipstock. While only
one centralizer is illustrated in the drawing, there are preferably
at least three centralizers on the upper portion to center the
whipstock in the hole. The centralizers can take other forms, as
desired.
[0108] A socket 58 extends from the bottom of whipstock 24 parallel
with central axis 52. Socket 58 is shaped to accept a male portion
68 on the lower orienting section 22, as will be discussed
hereinafter with reference to FIGS. 5A and 5B. Preferably, socket
58 is faceted at 60 and male portion 68 is similarly faceted so
that the parts lock together and male portion 68 cannot rotate
within socket 58. Shear pins 61 are inserted through apertures 62
to secure male portion 68 in socket 58 and thereby, the whipstock
to the lower section.
[0109] The whipstock is formed of hardened steel and has applied
thereto a polymeric coating 64 (shown only in FIG. 3B). Polymeric
coating 64 is, preferably, formed of cured polyurethane but can be
formed of other polymers such as epoxy. Coating 64 acts to prevent
damage of the metal components of the whipstock and can be
reapplied if it is removed during use. Coating 64 further
facilitates wash over operations, should they become necessary, to
remove the toolguide or whipstock from the casing. The coating is
thick enough so that it will accommodate normal damage from, for
example, abrasion and will prevent damage to the metal surfaces of
the whipstock and is preferably also thick enough so that
substantially only the coating will be removed by any washover
operation. In a preferred embodiment, the coating is about 1/2 inch
thick and is applied using a mold, so that the shape of the tool
after coating is controllable. If damage occurs to the coating, it
can be replaced. The maximum outer diameter of the whipstock to the
outer surface of the coating is selected to be smaller than the
inner diameter of the casing in which it is to be used. In
particular, the maximum effective outer diameter of the whipstock
is selected to be as large as possible without exceeding the drift
diameter (i.e. the maximum diameter permitted according to
regulations for any tool for use in a casing of a particular id)
for the casing.
[0110] Because coating 64 is easily abraded and, to a limited
degree, deformable, the coating can interfere with tool
centralization. Thus, to permit correct centralization of the
whipstock within the casing, preferably centralizers 56 extend out
from the metal portion of the whipstock a distance at least equal
with the thickness of coating 64. In this way, centralizers 56 are
either flush with the surface of the coating or extend out
therefrom.
[0111] Referring to FIGS. 4A to 4F, another whipstock 24' is shown.
Whipstock 24' includes a sloping face portion 26'. Generally,
whipstocks are useful for producing deviated wellbores having only
a selected one of a long, medium or short radius deviated wellbore.
However, the profile of sloping face portion 26' of whipstock 24'
is formed to allow flexibility to produce both medium and short
radius laterals.
[0112] Whipstock 24' is selected to be useful with a
running/retrieval tool as is described in more detail in FIG. 8. In
particular, whipstock 24' has formed at its upper end a dove-tail
slot 51 and a second slot 55. These slots will be described in more
detail with respect to FIG. 8.
[0113] Centralizers 56' are formed integral with the metal portion
of the whipstock. While six centralizers are shown, it is to be
understood that only three centralizers are required for proper
functioning.
[0114] Whipstock 24' includes a socket 58' which is generally
similar to socket 58 described with reference to FIG. 3B. Socket
58' includes a faceted portion 68. Apertures 62 extend through
centralizers 56' and open into socket 58' for accepting shear pins
(61' in FIG. 6A) for securing the whipstock to the lower
section.
[0115] A coating 64' of polymeric material is applied over selected
portions of whipstock 24'. As noted with respect to FIG. 3B,
preferably coating 64' is applied to be flush with the outer,
contact surface of centralizers 56'. The effective diameter of the
whipstock to the outer surface of the coating is substantially the
same as the effective diameter of the whipstock at the
centralizers, which is selected to be equal to or just less than
the drift diameter of the casing in which whipstock is to be
used.
[0116] In using whipstocks that are of a reduced diameter and have
applied thereover or attached thereto coatings or brass stand-off
rings or that have been modified in other ways to facilitate
washover or engagement by die collars or overshots, it has been
found that the surface area of the sloping face portion is greatly
reduced. This reduces the surface area which is available to guide
the drill bit or mill off the whipstock face and the mill or drill
bit tends to roll off the sloping face portion in the direction of
rotation.
[0117] To prevent roll off and to centralize and stabilize the
upper tapered end of the whipstock, while continuing to facilitate
washover procedures, the surface area of face portion 26' is
increased by an extension 65 which extends around face portion.
Extension 65 acts to extend the width of face portion 26' such that
the effective diameter of the whipstock at the extension 65 is
equal to or just less than the drift diameter for the whipstock
which is substantially equal to the effective diameter at the
centralizers. A cavity is formed on the outer surface of the
whipstock between the centralizers and the extension into which
coating 64' is applied. The radial length of the whipstock relative
to the long axis 52' is selected to be substantially equal along
the length of the whipstock. As an example, in the preferred
embodiment, the radial length r1 at the extension, the radial
length to the outer surface of a coated area r2 and the radial
length to the outer contact surface of a centralizer 56' r3 are
each substantially equal. The extension is preferably 1/2" to 1"
thick.
[0118] In FIGS. 5A and 5B, one embodiment of a lower orienting
section 22 is shown. FIG. 6A show another embodiment of a lower
orienting section 22'. Orienting sections 22 or 22' can be utilized
to position and orient any assembly in any desired depth profile
included in the casing string. This may include whipstocks, for
example as shown in FIG. 3A or FIG. 4A, packers, completion
diverters or tubing splitters or any other completion tools
required to be oriented in a particular location in the casing,
such as for example, adjacent a lateral window.
[0119] Section 22 is shown uncompressed in FIG. 5A. In FIG. 5B,
section 22 is shown in a compressed, set condition as would be the
condition of the section when used in a toolguide which is locked
in position in a wellbore ready for use. Lower orienting section 22
includes a male portion 68 shaped to fit into the sockets 58 or 58'
on the whipstocks. Bores 70 (only one is shown) accept ends of
shear pins 61.
[0120] Male portion 68 is connected to a central mandrel 72.
Central mandrel 72 is mounted in a bore 73 in a housing 74. Mandrel
72 is both moveable through and rotatable within bore 73 as limited
by movement of pin 76 on housing 74 in jay slot 78 formed in
mandrel 72. Mandrel 72 can be releasably locked in position in
housing by locking collet 77 frictionally engaging into knurled
area 77a.
[0121] Housing 74 includes a top portion 80 and a lower portion 82.
Each portion has a flange 84 which together retain an annular
packing seal 28. Top portion 80 is moveable towards lower portion
82 as shown in FIG. 5B to compress packing seal 28 and cause it to
expand outwardly.
[0122] Referring also to FIG. 5C, housing 74 at its lower end
accommodates latch assembly 83. Latch assembly 83 includes latch
20, a latch retaining plate 84 and springs 86. Springs 86 act
between latch 20 and latch retaining plate 84 to bias latch 20
radially outwardly from housing 74. Latch 20 is retained in a
channel 88 through housing 74 which opens into bore 73. Latch 20 is
prevented from being forced by the action of springs 86 out of the
channel, by abutting flanges 90 which act against shoulders 92 on
the latch. Latch 20 can be pushed into channel 88 by application of
force on the latch toward plate 84.
[0123] Latch 20 is formed to fit into latch retaining slot 16a on
casing 8 and has a ramped surface 94 on its upper edge, to ease
removal from the slot, and an acute angle portion 96 which acts as
a catch to resist against the latch moving out of the slot by any
downward force.
[0124] Mandrel 72 is bifurcated at is lower end to form two arms
98a, 98b. Arms 98a, 98b are formed to be extendable through bore 73
on either side of latch 20. Arms 98a, 98b are generally
wedge-shaped to permit rotation of mandrel 72 in bore 73. As
mandrel rotates, arms 98a, 98b are driven from a position in which
they do not restrict movement of the latch in the channel to a
position in which arm 98a abuts against shoulder 99 of latch 20 and
prevents it from moving back into channel 88. In this way arm 98a
can be moved to act as a lock against retraction of latch 20 into
channel 88. Arm 98b serves to stabilize the end of the mandrel,
but, can be omitted from the mandrel, as desired.
[0125] In use, a toolguide is constructed by attaching a whipstock
(ie. FIG. 3A or FIG. 4A) to lower section 22 by insertion of shear
pins 61 through apertures 62 and 70. The toolguide is run into the
well until the latch 20 is about 1 meter below the slot 16a in
casing section 8. The toolguide is hoisted and rotated slowly,
until latch 20 is located in slot 16a. When the latch is located in
the slot, the torque load will suddenly increase. As the string
torques up, jay pin 76 will release, allowing mandrel 72 to rotate
in a direction indicated by arrow a. When the force on the
toolguide is released, the mandrel will be free to move down in
housing 74 (FIG. 5B). During rotation of the mandrel, arms 98a, 98b
will be rotated so that arm 98a abuts against shoulder 99 of latch
20 and locks latch in the outwardly biased position. Mandrel arms
can take other forms provided they are formed to lock behind the
latch in response to rotation of the mandrel and/or movement of the
mandrel through the housing.
[0126] A downward movement of the string allows the toolguide to
travel down until portion 96 of the latch lands against the bottom
of slot 16a. Latch 20 and housing 74 will support the weight of the
tool and upper portion of the housing will be driven down by the
weight of the whipstock to compress seal 28 allowing it to set. The
set force is locked in by collet 77. The whipstock 24 is now
aligned with window opening 12 and the directional drilling
operations can begin.
[0127] After the directional drilling operations are completed, a
retrieving tool is run in to retrieve the toolguide. Preferably, in
the simplest retrieval procedure, a straight upward force, for
example of about 20,000 psi on the toolguide will unlock locking
collet 77 and permit mandrel 72 to be pulled up. This pulls arm 98a
out of abutting engagement with the latch and releases seal 28. The
toolguide can then be removed from the well.
[0128] If the toolguide gets stuck in the well, a force is applied
which is sufficient to shear pins 61 so that the whipstock can be
removed separately from the lower section.
[0129] Referring to FIG. 6A, another lower section 22' is shown.
Lower section 22' is illustrated connected to a whipstock 24'.
Lower section 22' includes a male portion 68' shaped to fit into
socket 58' of whipstock 24'. Bores 70' accept ends of shear pins
61'.
[0130] Male portion 68' is an extension of a mandrel 172 which is
positioned in a bore 173 in housing 174. Mandrel 172 is slidably
moveable through bore 173 along long axis 178 of the lower section,
but can be releasably locked against longitudinal sliding movement
by frictional engagement of locking collet 177 against knurled
portion 177a of the mandrel. Mandrel 172 and bore 173 are
correspondingly faceted along corresponding portions of their
length to substantially prevent rotational movement of mandrel 172
within bore 173.
[0131] An annular packing seal 28 is retained on housing 174 and a
tube 179 is positioned to ride over an upper surface of housing
174. Tube 179 is releasably secured through shear pins 179a to
whipstock 24' to move therewith. Pressure of tube 179 against
annular packing seal 28, for example when the weight of the
whipstock is released onto the lower section, compresses the seal
and causes it to expand outwardly.
[0132] Lower section 22' carries a latch assembly including a latch
20', a latch retaining plate 184 and latch biasing springs 186.
Springs 186 act between latch 20' and plate 184 to bias latch 20'
to extend radially outwardly from housing 174. Latch 20' is formed
to fit into a latch retaining slot, such as slot 16a in FIG. 1.
[0133] Latch 20' is retained in a channel 188 which opens into bore
173. Latch 20' is prevented from being forced by the action of
springs 186 out of channel 188 by abutting flanges 190 which act
against shoulders 191 on the latch. Latch 20' has formed into its
surface an upper cavity 192 and a lower cavity 193.
[0134] Mandrel 172 has an extension 198 on its lower end which is
capable of fitting into cavity 192 when mandrel is moved toward the
latch. When extension 198 of mandrel 172 fits into the cavity,
latch 20' is prevented from moving back into channel 188 and,
thereby is locked in an outwardly extending position. To strengthen
the locking of latch 20' in the outward position, the latch
preferably has formed thereon a cavity on each side thereof for
accepting a pair of spaced extensions on the mandrel.
[0135] A rod 199 extends below latch 20 in a bore 200. Rod 199 is
slidably moveable in bore 200 and the rod and the bore are
correspondingly faceted along at least a portion of their lengths
so that rod 199 is substantially prevented from rotating within the
bore. Rod 199 has an end 199' which is capable of fitting into
lower cavity 193 on latch 20'. End 199' is tapered to facilitate
entry into lower cavity 193 even when the rod end and the cavity
are not directly aligned, but cavity is formed such that when latch
20' is biased outwardly into a slot in the casing, end 199' will
not align with and fit into the cavity. When end 199' is inserted
into cavity 193, the latch is maintained in a recessed position in
the channel and is prevented from being biased to extend fully
outwardly. Thus, rod 199 acts as a lock for maintaining latch 20'
in a recessed position within channel 188. Apertures 201 are formed
through housing 174 for alignment with holes 202 on rod 199. Shear
pins (not shown) can be inserted through apertures 201 into holes
202 to releasably lock rod 199 against slidable movement in bore
200. Other releasably lockable means can be used in place of shear
pins such as spring biased pins or a locking collet. A releasable
locking means which can be repeated locked and unlocked is
preferred where the tool is to be repeatedly used downhole without
being brought back to surface.
[0136] Rod 199 extends out of housing 174 and opposite rod end 199"
is retained in a bore 204 formed in a lower housing 206. A portion
of end 199" is enlarged so that rod is retained in the bore.
However, bore 204 is selected to have a greater inner diameter,
ID.sub.b, than the width, w, of end 199" so that rod 199 can move
laterally within bore 204. This forms a wobble shaft arrangement
and provides that housing section 206 can move out of axial
alignment with axis 178 of housing 174.
[0137] Housing 206 houses an orienting assembly including a
plurality of orienting dogs 208. Preferably, there are four
orienting dogs spaced apart 90 degrees aligned around a
circumference of the housing. Dogs 208 are retained in housing in
any suitable way such as by abutting flanges, not shown. Dogs 208
are biased outwardly by springs 210, such as Belleville washers,
which are actuated to apply various, selectable degrees of force to
the dogs. Springs 210 are actuated to vary their biasing force by a
hydrostatic piston assembly 212. In particular, piston 212 includes
a piston 214 having a face 214' in communication with a chamber 216
opening though aperture 218 to the exterior of the tool. Opposite
face 214" of the piston is open to a chamber 219 containing a fluid
selected to be at a pressure generally corresponding to ground
surface atmospheric pressure. Piston 214 is drivingly connected to
rod 220 and rod cup 222. Upper end 222' of rod cup 222 is drivingly
connected to springs 210.
[0138] As the pressure in chamber 216 increases relative to the
pressure in chamber 219, piston 214 will be driven to drive rod 220
and rod cup 222 to compress springs 210. It will be readily
understood that movement of the rod cup varies the pressure applied
to the springs and thereby the pressure at which dogs 208 are
biased outwardly from housing 204. Rod cup 222 is preferably
limited in travel so as to apply a limited degree of force on
springs 210. In particular, in a preferred embodiment, the rod cup
travel is required only to preload springs past 400 meters depth.
Extra force action on the piston beyond this depth is not
transmitted to the springs. Preferably, at maximum compression
springs 210 are selected to bias dogs 208 outwardly at a pressure
of 20,000 to 30,000 psi and preferably 25,000 psi. The springs can
be replaced with other biasing means such as a hydraulic means
which is acted upon by the hydrostatic piston. In addition, the
assembly can be selected to act on the dogs from both the bottom
side and the top side or just from one side, as shown.
[0139] Where greater load is required to be applied to the dogs,
additional hydrostatic pistons can be added in series.
[0140] Where an orienting section is required that does not
restrict fluid flow past the tool, a bore can be formed through the
tool. Referring to FIG. 6B, an orienting tool is shown including a
central bore 207. The tool includes a set of dogs 208' biased
outwardly by springs 210'. Springs 210' are acted upon by a
torus-shaped piston 215 which has an end 215' open to the
hydrostatic pressure in the well and another end open to chamber
219'. The pressure of the fluid in chamber 219' is maintained at
atmospheric pressure. A latch 20' is spaced from dogs 208'. Latch
20' is biased outwardly by springs 186.
[0141] The lower sections of FIGS. 6A and 6B are useful with a
casing section 224 as shown in FIGS. 7A to 7C. To fully understand
the operation of the lower sections to orient and lock a toolguide
into position, we must first review the structure of the casing
section. The operation of the lower sections will be described only
with reference to the orienting section shown in FIG. 6A, although
the operation of the orienting section of FIG. 6B would be
similar.
[0142] Because of the length of casing section 224, it has been
separated into three views. As shown in FIG. 7, FIG. 7A shows the
lower portion of the casing section, FIG. 7B shows the middle
portion of the casing section and FIG. 7C shows the upper portion
of the casing section. For ease of production and handling, the
casing section can be produced in separate sections, as shown, for
connection together. Alternately, the casing section can be formed
as one piece. Casing section 224 is used with other sections, such
as those indicated as sections 6 in FIG. 1 to form a casing string.
Casing sections 6 can be connected below the section by threaded
engagement to pin end 224' in FIG. 7A and casing sections can be
connected above casing section 224 by threaded connection to box
end 224" in FIG. 7C.
[0143] Casing section 224 includes a window opening 112 which is
sized and shaped to permit any various assemblies to pass
therethrough, such as directional drilling and completion tools.
Casing section 224 retains therein a sleeve 123 as will be
described hereinafter.
[0144] A radial profile 230 is formed at a selected distance below
window 112. Radial profile 230 is selected to have a length Lp
greater than the axial length Ld of dogs 208 (FIG. 6b) so that dogs
208 can be accommodated in profile 230. Casing section 224 also
includes a latch receiving slot 16a formed a selected distance
below and a selected radial orientation from window 112.
Preferably, latch receiving slot 16a is positioned directly below
the window for ease of manufacture. Latch receiving slot 16a is
selected to be of a size to accommodate the face of latch 20'.
[0145] In use a toolguide including lower section 22' and whipstock
24' is run into a casing string including section 224. The lower
section is selected such that both the diameter across dogs 208,
when they are fully extended, and the diameter of the tool across
seals 28, will be greater than the diameter of the casing. Since
dogs 208 are biased outwardly, they will engage against the surface
of the casing.
[0146] A running tool is connected to whipstock and the weight of
the tool guide is supported on running tool. At surface, the tool
is in the relaxed, unset position (not shown). In particular, the
shear pins are inserted through apertures 201 into holes 202 which
locks housing 174 down in close position to housing 206 and
maintains end 199' in cavity 193 to retain latch 20' in a recessed
position. To maintain this configuration during handling, the shear
pins at this connection are selected support the weight of the
housing 206 and its components. No weight of the whipstock is
applied at locking collet 177 and therefore substantially no
engagement is made between the locking collet and portion 177a.
Finally, the pressure in chamber 216 is generally equal to the
pressure in chamber 219. Thus, piston is equalized and
substantially no pressure is applied at springs 210 of dogs 208.
Dogs 208 are therefore biased outwardly a minimum selected
pressure, for example, 0 to 500 psi and are capable of being driven
inwardly to move into and along the casing string.
[0147] As the tool is being run into the casing string, the
hydrostatic pressure of the fluids in the well about the tool will
increase as the depth of the tool increases. As the pressure of the
well fluids increase, the pressure in chamber 216 increases
relative to the fixed fluid pressure in chamber 219. This pressure
differential causes piston 214 to be driven into chamber 219.
Movement of piston 214 is translated to rod 220 which, though rod
cup 222, compresses springs 210. Compression of springs 210 drives
dogs 208 outwardly at increased pressures until maximum pressure is
reached. When maximum pressure is reached the weight of the running
string is sufficient to drive the tool through the casing string.
However, the pressure biasing the dogs outwardly is selected such
that it will affect the load required to move the tool though the
casing. In one embodiment, the maximum biasing pressure on dogs 208
is selected to be about 20,000 to 30,000 psi. Preferably, the
leading, lower edges 208' of the dogs are sloped to facilitate
movement of the dogs over raised or recessed portions of the casing
string.
[0148] It will be appreciated that, because of the alignment of the
dogs about a circumference of the lower section and the pressure
acting on the dogs, it will be determinable, by overpull or by a
decrease in string weight, when the dogs have passed from the
standard casing diameter over or into a profile such as profile 230
in the casing. Preferably, the trailing, upper edge 208" of each
dog is selected to be square or only slightly sloped to engage more
firmly against raised shoulders in the casing. Thus, to ensure that
the dogs are located in profile 230, the toolguide can be pulled up
while monitoring the force on the running string to confirm that
the dogs have engaged in and against the upper shoulder of the
profile.
[0149] There can be further radial profiles similar to profile 230
along the casing. The radial profiles are non-selective. Any tool
having a set of dogs thereon will pass through each profile and as
the dogs pass downwardly through a profile there will be indicative
overpull or string weight decrease, depending the direction in
which the tool is being moved within the casing. Thus, tool
orientation along the length of the casing string can be determined
by monitoring the force applied to the running string to determine
when the dogs are located in profile 230 and referencing that
information to depth information to determine at precisely which
profile the tool is located.
[0150] The non-selective profiles can be utilized above or below
window openings at any known depth in the well. This is useful in
positioning a number of various tools relative to a window.
[0151] During use of the toolguide in a horizontal section of well,
the housing 206 can move laterally, at the connection of rod 199 in
bore 204, out of alignment with the remainder of the tool. This
prevents the dogs from being compressed by the entire weight of the
string.
[0152] During confirmation of dog orientation, sufficient pressure
will be applied to the string in a upward (toward whipstock)
direction, that shear pins in apertures 201 will shear (i.e. at
5,000 psi) and housing 174 will be pulled along rod 199 away from
housing 206. This will cause end 199' to be pulled out of cavity
193. The pressure of springs 186 behind latch 20' drives latch 20'
outwardly. If latch 20' is biased outwardly to its full extent such
that shoulders 191 abut against stops 190, then cavity 193 will
then be out of alignment with rod end 199', engagement cannot be
made again between latch 20' and rod 199, even where force is again
applied toward the lower section. Alternately, if the outward
movement, of latch 20' is restricted, as by abutment against a wall
of the casing, weight on the tool will drive end 199' back into
cavity 193 such that latch 20' will be retracted.
[0153] The distance between latch 20' and dogs 208 is selected to
be generally equal to the distance between profile 230 and latch
receiving slot 16a so that when dogs 208 are located in profile
230, latch 20' will be at the same position along the casing as the
slot 16a. Thus, by rotation of the tool, latch 20' can drop into
slot 16a. In this configuration sloping face 26' of whipstock 24'
will be oriented to direct tools moved along it, laterally
outwardly toward window 112.
[0154] When the running tool is removed from the whipstock, the
weight of the whipstock will be pushed down or set down on the
lower section causing tube 179 to force seal 28 to expand outwardly
and to cause extensions 198 of mandrel to move into cavity 192 to
lock latch 20' in outwardly extended position. Also when the weight
of the whipstock is set down on the lower section, locking collet
177 will be driven by its spring to engage against the knurled
portion 177a of mandrel.
[0155] While the embodiment of dogs 208 biased outwardly in
response to hydrostatic pressure is preferred, it is to be
understood that other assemblies for locating profiles such as
collar locators, sleeve shifting tools or collets can be used.
[0156] The tools disclosed herein must be run into and retrieved
from the well. Running and retrieval tools are known. However,
previous running and retrieval tools are sometimes difficult to
manipulate and operate. These previous tools are particularly
difficult to operate in horizontal runs of casing.
[0157] Previous running tools for whipstocks used shear bolts for
attachment between the running tool and the whipstock. These shear
bolts are prone to shearing prematurely if the whipstock is bumped
at surface while entering the will or sue to running the assembly
through a tight area in the casing. The shear bolt may also shear
prematurely if the assembly is rotated.
[0158] A new tool 270 which can be used for both run in and
retrieval of whipstocks is shown in FIG. 8. Tool 270 is intended
for use with a whipstock as shown in FIGS. 4A and 4B and a casing
section as shown in FIGS. 7A to 7C. To facilitate understanding of
the tool 270 reference should be made to those Figures.
[0159] Tool 270 is positively latched to the whipstock in a manner
that allows forces to be applied upwardly or downwardly as well as
rotationally without risk of prematurely releasing the whipstock.
At the desired time of release, hydraulic pressure is applied to
the tool to unlatch it from the whipstock.
[0160] Tool 270 includes a front end 270' and a threaded end 270"
for connection to a drill pipe, such as that shown as 32 in FIG. 1.
A bore 272 extends a portion of the length of the tool and opens at
end 270". A piston 274 is disposed to move slidably along a length
of bore between shoulders 276, 277 and a spring 280 is disposed
between piston 274 and an end wall 284 of bore 272 to bias the
piston outwardly against shoulder 276. A rod 286 is connected to
piston 274 and is driven thereby. Rod 286 is extends through a
channel 287 extending from bore 272 and has a tapered end 286'.
Preferably, rod 286 is bifurcated to form two arms, each with a
tapered end.
[0161] Tool 270 houses a latch assembly including a latch 288, a
latch retaining plate 290 and a plurality of springs 292 acting
between the latch 288 and the plate 290 to bias the latch radially
outwardly from the tool. Of course, the plate can be replaced with
an end wall formed integral with the body of the tool. However, a
plate is preferred for ease of manufacture. Latch 288 is retained
in a channel 294 through tool 270 which opens into channel 279.
Latch 288 can be recessed into channel 294 by application of force
sufficient to overcome the tension in springs 292 on the latch
toward plate 290. Latch 288 is prevented from being forced by the
action of springs 292 out of the channel, by abutting against end
286' of rod 286 which extends into channel. In particular, latch
288 has a ramped surface 296 over which tapered end 286' can
ride.
[0162] Movement of rod 286 through channel 287, by movement of
piston, causes latch 288 to be moved radially inward and outward in
tool, by movement of tapered end 286' over ramped surface 296.
Thus, by controlling the pressure acting on piston face 274', latch
288 can be selectively moved.
[0163] Latch 288 is formed to fit into a slot, such as slot 55 on
whipstock 24' of FIG. 4A. Latch has a ramped surface 300 on its
front edge, to ease the movement of the latch over protrusions. A
reverse angle portion 302 is provided on the rear edge of the latch
which acts as a catch to resist against the latch moving out of the
slot by any force applied toward end 270".
[0164] Tool 270 further includes an orienting key 304 retained in
cavity 305. Key 304 is biased radially outwardly from the tool by
means of springs 306 acting between the key and an end wall 305a of
cavity 305. Key 304 is prevented from being forced out of cavity
305 by shoulders 308. Key 304 is selected to fit into an orienting
slot on a casing section, such as slot 309 in casing section
224.
[0165] Tool 270 has formed thereon a dove-tailed rail 310. Rail 310
is selected to fit into a dove-tail slot on a whipstock, such as
that indicated as slot 51 in FIG. 4A. Rail 310 is oriented relative
to latch 288 with consideration as to the orientation of slots 51
and 55 on the whipstock with which the tool is to be used. Rail 310
is spaced from latch 288 a selected distance which corresponds to
the distance between slot 55 and 51 on the whipstock. Preferably,
rail 310 is formed to be in longitudinal alignment with latch 288.
Rail 310 is oriented on the tool relative to key 304, with
consideration as to the orientation which slot 309 has relative to
a slot 51, when a whipstock is mounted in the casing section. In
the illustrated embodiment, slot 309 is longitudinally aligned with
window. Thus, when a whipstock is mounted in the casing section,
the sloping face of the whipstock will be positioned opposite the
window and slot 309 and in the illustrated embodiment rail 310 is
spaced 180 degrees from key 304.
[0166] Another key 312 is preferably provided on the tool and
spaced 180 degrees from rail 310. Key 312 rides in a port 314
opening between the outer surface of the tool and bore 272. Key 312
can be moved along a portion of the port 314 as limited by
shoulders 316a, 316b.
[0167] Tool 270 preferably includes a first fluid delivery port 318
extending between bore 272 and an end 310' of rail 310. A second
fluid delivery port 320 extends between bore 272 and a position
adjacent latch 288.
[0168] In use in a running operation, tool 270 is attached to
whipstock 24' at surface. This is done by advancing the tool toward
the whipstock so that rail 310 is inserted into slot 51. This
requires that latch 288 be forced into channel 294 by any suitable
means. When rail 310 is fully inserted in slot 51, latch 288 will
engage in slot 55. A drill pipe is attached at end 270". Latch 288
is maintained in slot by action of springs 292.
[0169] Tool 270, with whipstock 24' attached, is then run into the
well on the drill pipe. When whipstock is properly mounted in the
casing, whipstock 24' is released tool 270 by applying pressure
against the piston to drive rod 286 through channel 287 to,
thereby, drive latch 288 into a recessed position in the tool.
Pressure can be applied to the piston, for example, by forcing a
drilling fluid, such as mud, through the drill pipe into bore 272.
Application of drilling fluid increases the pressure in the bore
and drives piston 274 against spring 280, which in turn drives rod
286 to advance against latch 288.
[0170] When latch 288 is removed from slot 55, rail 310 can be
removed from slot 51. Tool 270 is then free to be returned to
surface.
[0171] To use tool 270 in a retrieval operation, the tool is run in
on a drill pipe until it runs into the whipstock. The tool is then
pulled out a short distance and is rotated until key 304 drops into
slot 309. Because the orientation of slot 309 with respect to a
whipstock mounted in the casing section is selected to correspond
to the location of key 304 with respect to rail 310, the rail will
be aligned with slot 51 of the whipstock when key 304 is engaged in
its slot 309.
[0172] Pressure is then applied to piston, such as by pressuring up
the drill string, to retract latch 288 so that the tool can thus be
advanced to insert rail 310 in slot 51. Applying fluids to bore 272
also serves to cause fluid to be passed through and out ports 318
and 320 at high pressures to clean out slots 51 and 55 which may be
filled with debris. Pressure in bore 272 also acts against key 312
to cause it to be driven radially outwardly from the tool. This
causes the rail to be driven toward the casing wall. Key 312 is
particularly useful when the tool is used in horizontal runs of
casing. In horizontal wells, the whipstock is sometimes mounted
against the upper side of the casing, as determined by gravity.
When the tool is used to latch onto the whipstock, the weight of
the tool and drill pipe will cause key 304 to be driven into cavity
305. Thus, rail is out of position for insertion into slot and will
simply ride under the sloping face of the whipstock. Key 312 can
then be used to raise the tool toward the upper side of the well
casing so that rail 310 can align with slot 51.
[0173] When rail 310 is inserted fully into slot 51, the drill pipe
can be depressurized to permit the latch to be biased outwardly
into slot 55. Tool 270, with whipstock 24', attached can then be
retrieved back to surface.
[0174] When rail 310 and latch 288 are engaged in their respective
slots on the whipstock, all forces, either longitudinal or
torsional, which are applied to the tool are directly transmitted
to the whipstock. Tool 270 permits both run in and retrieval and is
useful in horizontal well sections.
[0175] Referring to FIG. 9, another casing section 108 is shown.
Casing section 108 is useful in the drilling and completion of
deviated well bores. It is used attached to other casing sections
such as those indicated as sections 6 in FIG. 1 to form a casing
string.
[0176] Casing section 108 includes a window opening 112 and a
sleeve 123. Casing section 108 has a known internal diameter,
indicated at IDc. Casing section 108 is formed or assembled in such
a way as to allow the placement of a sleeve 123 internally. In
particular, a cylindrical groove 119 is formed in the inner surface
of the casing. Groove 119 has a larger inner diameter than the
casing such that, when the sleeve is disposed therein, the sleeve
and the casing on either side of the sleeve have the same ID. A key
121 is secured, as by welding, in the groove adjacent its bottom
edge.
[0177] Sleeve 123 is disposed in groove 119. An embodiment of the
sleeve for use in the embodiment of FIG. 9 is shown in flattened
configuration in FIG. 10. To ready the sleeve shown in FIG. 10 for
use, sides 123a, 123b of the sleeve are brought together and
preferably attached, as by welding.
[0178] Sleeve 123 has a key slot 125 at its lower edge to engage
key 121. Key slot 125 has two locking slots 125a and 125a.sup.1 and
a ramped portion 125b therebetween to facilitate movement of key
121 between slots 125a, 125a.sup.1. Sleeve 123 is rotatable and
longitudinally moveable in groove 119 and key slot 125 is formed to
limit the movement of sleeve 123 over key 121 between a first
position at locking slot 125a and a second position at locking slot
125a.sup.1. Sleeve 123 is selected to have an inner diameter IDs
which is greater than or equal to the inner diameter IDc of casing
108.
[0179] Sleeve 123 has a first opening 127 which is larger than
window opening 112 but is positioned on the sleeve such that it can
be aligned over window opening 112. Sleeve 123 preferably also has
a second opening 129 which is substantially equal to or smaller
than window opening 112. Second opening 129 is shown spaced about
180 degrees from opening 127 in FIGS. 7A to 7C, while in FIG. 9
opening 129 is rotated only about 80 degrees from first opening
127. Second opening 129 is also positioned on sleeve 123 such that
it can be aligned over window opening 112. Key slot 125 is shaped
relative to key 121 to permit movement of the sleeve to align one
of the first and second openings 127, 129 over window opening 112
and locking slots 125a, 125a.sup.1 are positioned to lock the
sleeve by its weight at these aligned positions.
[0180] Seals 131 are provided at the upper and lower limits of the
sleeve between the sleeve and groove 119. In the embodiment of FIG.
10, seals 133, 135 are also provided about openings 127 and 129,
respectively. Seals 131, 133, 135 are each formed of materials
which are hydraulically sealing such as o-rings positioned in
retaining grooves or lines of vulcanized polymers such as urethane.
Preferably, the seating areas for the seals are treated, for
example by machining to provide a smooth surface, to enhance the
sealing properties of the seals. The seals act against the passage
of fluids between the sleeve and the structure to which they are
seated, for example the casing or the flange of a tieback hanger.
In an alternate embodiment, the seals are secured to the casing and
the sleeve rides over them.
[0181] In the embodiment of FIG. 10, an aperture 137 is provided on
the sleeve which is sized to accept, and engage releasably latches
on a shifting tool (not shown). The latches of the shifting tool
hook into apertures 137 on sleeve 123 and shift tool is raised to
pull the sleeve upwardly to release key 121 from locking slot 125a
or 125a.sup.1 into which the key is locked. The shifting tool then
rotates sleeve 123 within groove 119.
[0182] The sleeve can be shifted by other means such as a sleeve
shifting tool, as will be described in more detail hereinafter,
having pads with teeth formed thereon for being forced against the
sleeve material so that the sleeve can be rotated in the
groove.
[0183] Window opening 112 has a profiled edge 113. Edge 113 is
formed to accommodate and retain a flange 115 (FIG. 11A) formed on
a deviated wellbore liner or tieback hanger 117.
[0184] In use, casing section 108 having sleeve 123 disposed
therein is prepared for placement downhole by aligning opening 127
over window 112. To prevent inadvertent rotation of sleeve 123 in
its groove, shear pins 138 are inserted to act between the sleeve
and the casing section. A liner is then inserted through the
internal diameter and opening 112 is filled and wrapped, as
discussed with respect to FIG. 2. A casing string is formed by
attaching casing section 108 to other casing sections selected from
those which have window openings or those which are standard casing
sections. The casing string is then inserted into the wellbore and
is aligned, as desired. The wellbore is then completed.
[0185] After completion, the hardened cement and the liner are
removed from the casing string. This exposes sleeve 123 within
casing section 108. A toolguide, for example, according to FIG. 1
or any other toolguide, is positioned in the well such that the
face of its whipstock is opposite opening 112 and a deviated
wellbore is drilled.
[0186] Once the deviated wellbore is drilled, at least a junction
fitting such as a tieback hanger 117 is run into the well and
positioned such that its flange 115 is engaged on edge 113. Sleeve
123 is then lifted and rotated by engaging the setting tool in
apertures 137 such that opening 129 is aligned over opening 112 and
thereby the central opening of the tieback hanger. This causes
seals 135 to seal against flange 115 and prevents fluids from
outside the deviated casing from entering into casing section 108
at the junction. Using the sleeve of the present invention, the
deviated wellbore does not need to be completed using cement to
seal against passage of fluids outside the casing. However, where
desired, the deviated wellbore can be completed using cement to
increase the pressure rating of the seal.
[0187] The sleeves according to the present invention can be
rotated using any suitable tool. A tool which engages in apertures
137 can be used or alternately a sleeve shifting tool 450 can be
used as shown in FIGS. 16A and 16B which does not require the
alignment of dogs into apertures but rather frictionally engages
the sleeve. In particular, tool 450 is sized to be insertable into
the inner bore of the casing and sleeve and includes an elongate
body 452. A plurality of sleeve engaging slips 454a, 454b are
mounted in the body to be moveable radially inwardly and outwardly
between a retracted position (i.e. 454a') and an extended position
(i.e. 454b'). In the extended position, the slips 454a, 454b are
selected to frictionally engage against the sleeve with sufficient
force to permit lifting and rotating of the sleeve.
[0188] Preferably, the sleeve engaging slips are selectively
positioned along the tool so that they will engage the sleeve
adjacent the upper and lower edges thereof and at a plurality of
positions about the inner radius. The sleeve engaging slips can be
formed in any suitable way to engage against the sleeve. In one
embodiment, the sleeve engaging faces 455 of the slips are
roughened or knurled or have teeth formed thereon in a suitable way
to permit the slips to bite into the material of the sleeve. In the
illustrated embodiment, slips are provided in two orientations.
Slips 454a are selected to enhance frictional engagement to provide
for longitudinal movement (ie. lifting) of the sleeve and slips
454b are selected to enhance frictional engagement to provide for
rotational movement of the sleeve. In particular, slips 454a
include elongate teeth 456a formed orthogonal to the long axis 452x
of the body 452 and slips 454b include elongate teeth 456b formed
substantially parallel to long axis 452x. Preferably the teeth
456a, 456b are formed with leading edges formed to define acute
angle so that they exhibit enhanced frictional engagement in one
direction.
[0189] Sleeve engaging slips 454a, 454b can be moved radially
inwardly and outwardly between the retracted position and the
extended position in any suitable way. In the illustrated
embodiment, the slips 454a, 454b are moveable by changes in fluid
pressure as controlled from surface. In particular, body 452 is
formed as a tube having an inner bore 458 closed at one end 452a by
a plug 458b. Body 452 is connected at opposite end 452b to a tubing
string 459 extending upwardly toward surface such that bore 458 can
be pressured up by feeding a fluid from surface through tubing
string 459.
[0190] Slips 454a, 454b are mounted in ports 460 to be radially
slidable therein relative to the long axis of the tool. The outer
diameter of the slips conform closely to the inner diameter of the
ports so that resistance is provided to fluids passing
therebetween. O-rings 463 are provided about the slips to form a
seal between ports 460 and slips 454a, 454b. Ports 460 open into
bore 458 to be in communication therewith and open to the outer
surface 452' of body 452. Ports 460 have a reduced diameter at
portion 460' to prevent slips 454a, 454b from dropping into bore
458 and straps 464 are mounted, as by use of fasteners or
weldments, across ports adjacent outer surface 452' to hold the
slips in the ports. Slips 454a, 454b each include a slot 466
extending across the engaging face thereof to accept strap 464.
Slot 466 permits the engaging face of the pad to extend out beyond
strap. As will be appreciated, strap 464 also prevents the rotation
of the slips within the ports, thereby preventing the teeth from
rotating out of their selected orientation. Springs 467 are
provided between the straps and the slot 466 to bias the slips
inwardly. Preferably, straps 464 are not intended to hold the slips
in the ports against fluid pressure behind the slips. Instead, the
tool is intended only to be pressurized while within a member such
as the casing which prevents the slips from extending to bear
against the straps.
[0191] Although FIG. 16B appears to show that a plurality of slips
are positioned in close proximity about the tool, preferably there
are two to four slips 454a positioned at each of the top and the
bottom of the tool. In each position, these slips are equally
spaced apart around the circumference. The same arrangement is
selected for the slips 454b.
[0192] As noted above, the slips 454a, 454b are moveable by changes
in fluid pressure in bore. In use, when the pressure of the fluid
in bore 458 is increased relative to the pressure about the tool,
slips 454a, 454b are driven outwardly through ports 460 against the
tension in springs 467 and into extended position until the slips
engage against the sleeve. If a sufficiently high pressure is
provided to the bore, the slips will bite into the sleeve with a
frictional engagement sufficient to move the sleeve by movement of
the tool, as by movement from surface. If the pressure is
maintained, the slips will remain in the extended position. If the
pressure is lowered, to a pressure relatively equal to or less than
the ambient pressure around the tool, the slips will be retractable
and will not maintain a frictional engagement with sleeve which is
sufficient to move the sleeve by movement of the tool.
[0193] To assist in the pressurization of the bore, a check valve
468 is provided adjacent end 452b, either in the bore of the tubing
string 459, as shown, or in bore 458 of body 452 above the upper
set of slips. Check valve 468 permits the flow of fluid behind
slips 454a, 454b, but substantially prevents fluid from passing
upwardly out of bore 458. Thus, pressure can be maintained behind
the slips to maintain them in an extended position without
maintaining the pressure in the entire tubing string to surface.
When check valve 468 is used, a means for releasing the pressure
from within the bore is required in order to permit the tool to be
disengaged from the sleeve, once the sleeve has been shifted. As an
example, valve 468 can be mechanically or electrically openable or
a vent can be provided. In the illustrated embodiment, plug 458b is
burstable by application of pressure greater than a selected value.
Therefore, when it is desirable to release the tool from engagement
with the sleeve, further fluid pressure is forced into bore 458
through check valve 468 until plug 458b bursts allowing
equalization between the bore pressure and the pressure about the
tool.
[0194] To permit proper positioning of the tool at the location of
the sleeve in the well bore, a wobble shaft arrangement 470 and an
orienting assembly 471, as discussed hereinabove with respect to
FIG. 6, can be used.
[0195] The sleeve according to the present invention can be
modified to permit other uses. For example, a sleeve can be used
which has one or two openings. One of the openings of the sleeve
can be aligned with a casing window opening, while the sleeve can
be repositioned such that a solid portion of the sleeve blocks the
window opening. Referring to FIG. 12, sleeve 223 is shown in
flattened configuration and when readied for insertion into a
groove of a casing section sides 223a, 223b are brought together. A
key slot 225 is formed at the lower edge of sleeve 223 for riding
over a key formed in the groove of the casing section in which the
sleeve is to be used. Key slot 225 has three locking slots 225a,
225a' and 225a" to permit sleeve 223 to be moved between three
positions. The first position of which is where the key is locked,
by the weight of the sleeve, into slot 225a and opening 127 is
aligned with the window opening of the casing section. The second
position is that in which the key is locked into slot 225a' and
opening 129 is disposed over the casing window opening. The third
position is the one in which the key is locked into slot 225a" and
a solid portion of the sleeve indicated in phantom at 234, is
disposed to block off the window opening of the casing section. The
sleeve can be moved between any of these positions by a shifting
tool. The groove into which the sleeve is mounted is formed to
accommodate such movement.
[0196] Seals 233, 235 are provided around openings 127, 129 and
seals 231 are provided around the upper and lower regions of sleeve
223 to hydraulically seal between the sleeve and the casing into
which the sleeve is mounted. The seals are on the other side of the
sleeve and are shown in phantom in this view.
[0197] Referring to FIG. 11B, generally the tieback flanges are
formed as tabs 115' and are disposed on the tieback 117 to extend
out from the sides thereof. There can be two tabs 115', as shown,
or four tabs 255 shown in phantom. Because of the arrangement of
the tabs and the way in which they extend out from the sides of the
tie back, it has been difficult or impossible to use a liner having
an outer diameter just less than the inner diameter of the casing
through which it is to be run. In particular, in such an
arrangement, the casing window is so large across its width that
the flange tabs have nothing to latch against.
[0198] Referring to FIG. 11C, a tieback hanger 117' has been
invented which is useful for use in tying back a liner having an
outer diameter close to that of the casing inner diameter. Tieback
hanger 117' has flanges 252 positioned at the top and bottom of its
open face 254.
[0199] Tieback hanger 117' is intended to be used with a casing
section, such as that shown in FIGS. 7A to 7C and in FIG. 13. The
casing section includes a wall 256a extending out into window 112
adjacent the top thereof and another wall 256b extending out at the
bottom of the window. Walls 256a, 256b provide surfaces against
which flanges 252 can latch. Walls 256a, 256b are recessed relative
to the inner surface of casing section 224, so that when flanges
252 latch against the walls, sleeve 123 can be rotated over the
open face 254 of the tieback hanger to hydraulically seal off the
liner. In this embodiment, preferably, the open face 254 of the
tieback hanger has bonded thereto, as by vulcanization, a polymeric
material 258 such as, for example, urethane to seal against the
sleeve.
[0200] Walls 256a,256b can be partial or complete. Preferably the
walls are disposed at the top and bottom of the window and form a
V-shaped opening. The walls can be formed integral with the casing
section 224 or can be attached, as by welding, to the outside of
the casing section.
[0201] To facilitate use of the tools and the casing sections
described herein and others not herein described, preferably a high
side tool is used. To facilitate use of the high side tool,
preferably sensors such as, for example, magnetic sensors, are
mounted in the tools and/or the casing section components (ie. the
sleeve), for reading by the high side tool. The sensors are
preferably mounted so that it can be determined both (a) where the
high side, according to gravity, is and (b) the degree to which any
well component has been rotated.
[0202] Another problem which occurs in downhole assembly
manipulation is the orientation of the tieback hanger in proper
position for insertion through the window. Previous tools actuate
the tieback hanger and liner too slowly and therefore increase the
chances of the liner being stuck against a negative pressure
formation.
[0203] Referring to FIG. 14, a tool 330 has been invented which
useful for downhole placement and positioning of tieback hangers.
Tool 330 includes a housing 332 with a bore 334 extending
therethrough. Slidably positioned in bore 334 is a rod 336. Rod 336
and bore 334 are similarly faceted at least along a portion of
their lengths so that rod 336 is substantially prevented from
rotating in the bore. Rod 336 has a box end 336' for connection to
a drill pipe (not shown). Box end 336' acts to limit the sliding
movement of rod 336 through bore 334 by abutment against housing
332.
[0204] At its opposite end 336", the rod has formed thereon threads
338 for connection to a flex shaft which extends into a whipstock
and bends along the face thereof for connection to a hydraulic
liner running and setting tool, as are known (not shown). A
shoulder 340 is formed to abut against the end of the flex shaft,
when the flex shaft is engaged on the rod.
[0205] Housing supports a collet 341, a key 342 and a poppet 343.
Collet 341 includes a plurality of (ie. four) circumferentially
aligned dogs 344. Dogs 344 are biased radially outwardly by springs
345 and are selected to locate in a profile formed in a casing
section (not shown) for use with the tool. Preferably, the profile
is a radial groove to avoid having to properly orient the dogs to
drop into the profile and to thereby ease location of dogs 344
therein. Operation of dogs 344 is similar to the operation of dogs
208 of FIG. 6A.
[0206] Key 342 is biased radially outwardly from housing by springs
346 but is secured in the housing by walls 348. Rearwardly
extending arms 347 extend from key 342 into bore. Cavities 348 are
formed in rod 336 to accept arms 347, when they are aligned. When
key 342 is recessed into cavities, rod 336 is prevented from
sliding movement through bore 334. The diameter of the tool at key
342, when the key is fully extended is selected to be greater than
the diameter of the casing in which the tool is to be used. This
provides that when the tool is located in the casing, the key will
be forced against the tension in springs 346 into the housing. Key
342 has chamfered ends 342' to facilitate riding over protrusions.
The sides of key 342 (which cannot be seen) have substantially no
chamfer to be square or to form a reverse angle so that they will
tend to catch on protrusions in the casing. The key is formed to
fit into an orienting slot on the casing section in which it is to
be used. When whipstock is connected through the flex shaft to tool
330, the whipstock face is positioned in a selected orientation
relative to key 342. The selected orientation will depend on the
orientation of the slot for key 342 relative to the window opening
in the casing.
[0207] Poppet 343 is positioned in a hole 349 opening into bore 334
and is biased into the bore by a spring 350. A cavity 351 is formed
on shaft 336 for accepting head 343' of the poppet, when the head
and the cavity are aligned. When poppet 343 is positioned in cavity
351, shaft 336 is prevented from sliding movement within bore 334.
A seal 352 disposed about poppet 343 forms a chamber 354. The
pressure in chamber 354 is selected to be a level near surface
pressure. A port 356 extends from the exterior of the tool either
along shaft 336, as shown, or along housing to open adjacent head
343'.
[0208] Tool is used to rapidly position a tieback hanger for proper
placement in the window to affect latching of the tieback flange
against the window. In use, at surface tool is connected at end
336" to a flex shaft which has attached thereto a tieback hanger
and a hydraulic liner running tool. Housing 332 is moved along rod
336 until poppet 343 snaps into cavity 351. A drill pipe (not
shown) is attached at end 336' and the tool with attachments is
inserted into the well.
[0209] In the casing, dogs 344 ride along the inner surface of the
casing and key 342 is driven inwardly so that arms 347 engage in
cavities 348. As the tool run further into the well, the
hydrostatic pressure in the well will be communicated to head 343'
of the poppet through port 356. As the hydrostatic pressure
increases, poppet will be driven back into chamber 354 and out of
engagement with rod 336. This will release the full weight of the
rod and attachments onto key 342. Rod will remain in fixed position
relative to housing, however, because of arms 347.
[0210] The tool is run to a depth such that dogs 344 drop into
their profile in the casing. When the dogs are located in their
profile, the key will be positioned at the appropriate level to
engage in its slot and the tool need only be rotated to locate key
342 in its slot. When key 342 locates in its slot, springs 346
drive arms 347 out of cavities 348 and rod 336 will immediately
slide through bore 334 in response to the weight of the attached
tieback hanger and other attachments. Because of the fixed
orientation of key 342 relative to the tieback hanger face and the
fixed orientation of the key's slot relative to the casing window,
the tieback hanger will be advanced through the casing and the
window in proper position for latching the flanges onto the window
edge. The liner can then be manipulated using the hydraulic liner
running tool.
[0211] It will be appreciated therefore that this tool is
particularly useful in placement of a tieback hanger. The liner
remains stationary only long enough for the tool to be rotated to
located key 342 in its slot. This is a great reduction in liner
stationary time over previous tools and prevents liner lock up
against negative pressure formations.
[0212] The tools for formation and completion of deviated wells, as
described hereinbefore and other not specifically described herein,
require manipulation by rotation of the tool. In deep well
operation and particularly in horizontal well applications, it is
virtually impossible to rotate the tool by manipulation from
surface.
[0213] Referring to FIG. 15, according to one aspect of the present
invention, a motor 400 for imparting rotational drive such as, for
example, a mud motor is connected at an end of a drill pipe 32'
adjacent the tool 402 or well component to be rotated. The motor is
connected to the drill pipe such that when the motor is driven,
rotational force will be communicated to the drill pipe to cause it
to rotate within the casing.
[0214] Preferably, the motor is driven by pumping drilling fluid
therethrough. The motor is preferably a high torque, low speed
motor which is selected to stall when the load thereon exceeds a
selected level. In particular, when, for example, a tool is to be
rotated until a latch drops into a slot, the motor will have a
selected power to drive the drill pipe to rotate but when the latch
is positioned in the slot and the load increases, the motor will
stall to cease rotation of the drill string.
[0215] In an embodiment, where hydraulic pressure is required below
the motor, such as for example, where the tool 402 is like tool 270
of FIG. 13, a bypass valve 404 is positioned above motor 400 to
permit flow through a bypass port 406 passing without effect
through motor and extending towards tool 402.
[0216] FIG. 11C shows a tieback hanger which is useful for tying
back a liner having an outer diameter close to that of the casing
inner diameter. FIGS. 17 to 19B show another tieback hanger 500 and
casing 502 arrangement which is similarly useful but avoids
increasing the OD or decreasing the ID of the casing at the window
opening.
[0217] Tieback hanger 500 is intended to be used with a casing 502,
such as that shown in FIGS. 17 to 17B, having an window opening 504
formed therethrough. The casing wall edges 505 defining the window
opening include profiled areas 506, 508 formed from the thickness
of the casing wall material which extend inwardly over the window
opening. Preferably, the profiled areas are formed to extend from
the outer surface of the casing and to substantially follow the
circumferential curvature of the casing outer wall. Preferably, the
profiled areas are formed to taper gradually toward their edges so
that a beveled edge is formed. The profiled areas can be formed to
extend at selected positions around the window opening or about the
entirety thereof. In the illustrated embodiment, profiled areas 506
are formed adjacent the bottom of window opening 504 and profiled
areas 508 are formed adjacent the upper end of the window
opening.
[0218] Tieback hanger 500 includes a sleeve 510 including an
outboard end 512 for connection to a lateral liner (not shown) and
an anchored end 514 for connection to casing. End 514 has a lower
setting tab 516 and an upper setting tab 518 formed to engage
against the profiled areas 506, 508 formed about window opening
504. Setting tabs 516, 518 are formed to flare outwardly adjacent
the edge of end 514 and to mate with the profiled areas 506, 508.
Setting tab 516 forms a tapering dovetail configuration, as best
seen in FIGS. 18 and 18A, which can be wedged between profiled
areas 506 which form a tapering dovetail mortise, as best seen in
FIGS. 17 and 17A. This prevents the tie back from being pushed
entirely out of the window during setting. Upper setting tab 518 is
also flared to form a dovetail, as best seen in FIG. 19A, which can
be wedged against profiled areas 508. The thickness of setting tabs
516, 518 is preferably selected such that the end 514 substantially
abuts against the outer surface of the casing, while the setting
tabs substantially do not extend inwardly beyond the inner surface
of the casing. This selected thickness provides that a minimum
amount of material is added to the OD of the liner tieback.
[0219] When setting tabs 516, 518 are engaged against corresponding
profiled areas 506, 508, tieback hanger will extend through the
window opening and hang off from the casing.
[0220] In some wells, the laterals extend from the main well bore
in such a way that the liner tieback can drop back into the casing
and obstruct the passage of tools through the main well bore and
into the lateral. In one embodiment as shown, the tieback hanger
can be prevented from dropping into the casing by forming the edges
of the window opening to engage the end of the tieback hanger
against both passing through the window opening both outwardly and
inwardly into the casing bore. The edges of the window opening can
be formed so that the edges of the tieback hanger can snap into the
opening and be engaged therein. In particular, as best shown in
FIG. 17C, the window edges on which profiled areas 508 are formed
include a recess 520 formed in the thickness of the casing wall.
Recess 520 is formed between profiled area 508 and inner edge 522
of the window opening. Setting tab 518 is formed to wedge against
profiled area 508 and engage into recess 520. Setting tab 518
includes an extension 524 which can be snapped past edge 522 and be
accommodated in recess 520. The recesses and extensions can be any
suitable shape, provided that each extension can fit into its
corresponding recess. Preferably, trailing edges 525 of extensions
524 are chamfered to facilitate unsnapping of the tieback liner
from the recess, if desired. Recesses and extensions can be
elongate extending along selected lengths of the edges of the
window. However, the positioning of the recesses and extensions on
their respective parts must be selected so that they can be aligned
and mated into each other.
[0221] In one embodiment, the distance dl across the setting tab
518 is slightly greater than the distance d2 across the window
between the profiled areas 508. This increases the engagement of
the tieback hanger in the window opening and strengthens the casing
about the window by transmission of forces.
[0222] Preferably, all profiled areas 506, 508 and recesses are
formed in the wall thickness of the casing without changing the ID
or the OD of the casing at the window.
[0223] In addition to the recess/extension engagement or as an
alternative thereto, flanges 530 can be provided on the tieback
hanger to abut against the edges of the window opening when the
setting tab 516 are wedged between profiled areas 506. Flanges 530
acts to abut against the casing to prevent the tieback hanger from
tipping back into the casing bore. It is useful to provide both the
profiled area 530 and the recesses 520 to act as back up systems
against each other.
[0224] Preferably all parts of the tieback hanger either sit within
the window opening or extend outwardly of the window opening
without extending into the bore of the casing, so that a sleeve,
such as sleeve 123 of FIGS. 7A to 7C, can be rotated over the
window opening 504.
[0225] It will be apparent that many other changes may be made to
the illustrative embodiments, while falling within the scope of the
invention and it is intended that all such changes be covered by
the claims appended hereto.
* * * * *