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Inventors
George, Grant E. E.
Begg, Stephen M.
Application #
305775
Filed
Apr-16-1999
Published
Sep-4-2001
Current US Class
166/117.6
166/255.2
166/255.3
166/50
175/80
175/81
International Classes
E21B 007/08; E21B 047/08
Field of Search
166/50 166/117.5 166/117.6 166/252.2 166/252.3 166/381 166/387 175/61 175/79 175/80 175/81 175/82
Assignee
Schlumberger Technology Corp. (Sugar Land, TX)
Examiners
Suchfield; George
Attorney, Agent or Firm
Griffin; Jeffrey, Castano; Jaime, Curington; Timothy
US Patent References
| 4432417 |
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Control pressure ac... |
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| 5269374 |
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Locator method an... |
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| 5579829 |
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Keyless latch for ori... |
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| 5697445 |
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Method and appar... |
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| 5947198 |
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Downhole tool |
|
| 5996711 |
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Method and appar... |
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| 6012527 |
|
Method and appar... |
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Referenced by:
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Citation
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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.
Claims
What is claimed is:
1. 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.
wherein the at least one member is a spring loaded dog.
2. The orienting tool of claim 1, further comprising at least another member, the members comprising a ring of dogs mounted about a circumference of the tool body and each biased outwardly therefrom.
3. The orienting tool of claim 1 wherein the selected pressure is 20,000 to 30,000 psi during operation of the members to position the tool.
4. 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; and
a biasing means, wherein the at least one member is biased outwardly by the biasing means selected to exert increased pressure as the depth of the tool is increased.
5. The orienting tool of claim 1 wherein the profile is a groove sized to accept the at least one member therein.
6. 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 seat as to prevent the at least one member from moving past the profile using normal force; and
a latch mounted thereon and radially extendable therefrom for fitting into a slot formed in the casing and positioned at a selected radial position relative to the center axis of the casing.
7. The orienting tool of claim 6 wherein 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.
8. The orienting tool of claim 6 wherein 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 move out of axial alignment with the first part.
9. A tool for use in a wellbore conduit, comprising:
a body,
at least one member mounted on the body, and
a mechanism adapted to bias the member radially outwardly to engage the conduit, the member adapted to allow axial movement of the tool in the conduit but to provide resistance to the axial movement,
the mechanism being responsive to wellbore pressure to provide a biasing force on the at least one member.
10. The tool of claim 9, wherein the biasing force applied by the mechanism affects a load required to move the orienting tool through the conduit.
11. The tool of claim 10, wherein the conduit comprises a profile, and wherein alignment of the at least one member in the profile due to the biasing force applied on the at least one member is detectable by a decrease in the load.
12. The tool of claim 9, wherein the mechanism comprises a first chamber in communication with wellbore fluids, a second chamber having a reference pressure, and a piston between the first and second chambers.
13. The tool of claim 12, wherein the piston is adapted to apply the biasing force on the at least one member.
14. The tool of claim 13, wherein the biasing force increases with wellbore fluid pressure.
15. The tool of claim 14, wherein the mechanism further comprises a spring operably engaged with the at least one member, the piston adapted to compress the spring.
16. The tool of claim 9, further comprising at least another member biased radially outwardly by the mechanism.
17. The tool of claim 9, further comprising a latch adapted to latch into a profile of the conduit.
18. A method of positioning an orienting tool in a conduit in a wellbore comprising:
providing an orienting tool having a body and a member biased radially outwardly;
providing a wellbore pressure responsive mechanism to apply a biasing force against the member; and
running the orienting tool in the conduit, the member providing resistance to axial movement of the orienting tool, the resistance being decreased when the member is aligned with a profile of the conduit.
19. The method of claim 18, further comprising at least another member biased radially outwardly by the pressure responsive mechanism.
Description
FIELD OF THE INVENTION
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
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.
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.
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.
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
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.
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.
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.
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.
The sections are movable relative to one another and means are provided to translate such movement to actuate such means as a seal.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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:
FIG. 1 is a schematic representation of an embodiment of an assembly according to the present invention, the assembly being positioned in a wellbore;
FIG. 2A is a view showing the orientation of FIGS. 2B and 2C.
FIGS. 2A and 2B are a longitudinal section along a casing section for a deviated wellbore junction useful in the present invention;
FIG. 3A is a view showing the orientation of FIGS. 3A-1 and 3A-2;
FIGS. 3A-1 and 3A-2 are a front elevation view, partly cutaway, of a whipstock of a toolguide according to the present invention;
FIG. 3B is a view showing the orientation of FIGS. 3B-1 and 3B-2;
FIGS. 3B-1 and 3B-2 are a section along line 3B-1-3B-2 of FIG. 3A1;
FIG. 4A is a view showing the orientation of FIGS. 4A-1 and 4A-2;
FIGS. 4A-1 and 4A-2 are a front elevation view, partly cutaway, of a whipstock of another toolguide;
FIG. 4B is a view showing the orientation of FIGS. 4B-1 and 4B-2;
FIGS. 4B-1 and 4B-2 are a section along lines 4B-1-4B-2 of FIGS. 4A-1 and 4A-2;
FIGS. 4C and 4D are sectional views along line 4C--4C and 4D--4D, respectively, of FIG. 4B-2;
FIG. 4E is a bottom end view of FIG. 4B-1;
FIG. 4F is a top end view of FIG. 4B-1;
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;
FIG. 5B is a front elevation view of the toolguide of FIG. 5A in compressed configuration;
FIG. 5C is a section along line 5C--5C of FIG. 5A;
FIG. 6A is a view showing the orientation of FIGS. 6A-1 and 6A-2;
FIGS. 6A-1 and 6A-2 are longitudinal sections along another lower section of a toolguide in a set configuration;
FIG. 6B is a view showing the orientation of FIGS. 6B-1 and 6B-2;
FIGS. 6B-1 and 6B-2 are longitudinal sections along another lower section of a toolguide;
FIG. 7A is a view showing the orientation of FIGS. 7B to 7D;
FIGS. 7B to 7D are longitudinal sections along a casing section for a deviated wellbore junction;
FIG. 8A is a view showing the orientation of FIGS. 8B and 8C;
FIGS. 8B and 8C are longitudinal sectional views along a running/retrieving tool;
FIG. 9 is a longitudinal section along another casing section for a deviated wellbore junction according to the present invention;
FIG. 10 is a rear plan view of a sleeve according to the present invention in flattened configuration;
FIG. 11A is a sectional view through a deviated wellbore junction using a casing section according to the present invention;
FIG. 11B is a front elevation view of a tieback hanger;
FIG. 11C is a front elevation view of a tieback hanger;
FIG. 12 is a front elevation view of another sleeve according to the present invention in flattened configuration;
FIG. 13A is a view showing the orientation of FIGS. 13B and 13C;
FIGS. 13B and 13C are elevation views of a casing section including a window opening;
FIG. 14 is a longitudinal sectional view along a liner positioning tool;
FIG. 15 is schematic representation of a system for imparting rotational force on a drill pipe;
FIG. 16A is a longitudinal sectional view along a sleeve shifting tool according to the present invention;
FIG. 16B is front elevation view of a portion of the sleeve shifting tool of FIG. 16A showing the sleeve engaging slips;
FIG. 17 is an elevation view of a casing section including a window opening according to the present invention;
FIG. 17A is a sectional view along line A--A of FIG. 17;
FIG. 17B is a sectional view along line B--B of FIG. 17;
FIG. 17C is an enlarged view of an edge of the window opening, as noted in FIG. 17A;
FIG. 18 is a front elevation view of a tieback hanger in accordance with another aspect of the present invention;
FIG. 18A is a sectional view along line A--A of FIG. 18 showing the lower setting tab;
FIG. 18B is a sectional view along line B--B of FIG. 18 showing the mid setting flanges;
FIG. 18C is a sectional view along line 18--18 of FIG. 18 showing the upper setting tab;
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
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
In FIGS. 3A to 3B-2 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.degree., the build radius will be approximately 15.degree./30 meters drilled. Preferably, sloping face portion 26 is formed to be concave along its width.
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).
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. 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.
The whipstock is formed of hardened steel and has applied thereto a polymeric coating 64 (shown only in FIGS. 3B-1 and 3B-2). 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.
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.
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. 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.
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.
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.
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.
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. 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Referring to FIGS. 6A-1, and 6A-2; 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'.
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.
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.
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.
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.
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.
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.
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.
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.
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. Where greater load is required to be applied to the dogs, additional hydrostatic pistons can be added in series.
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 FIGS. 6B, 6B-1, and 6B-2 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.
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.
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.
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. 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'.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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".
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.
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.
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.
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.
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. 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
In the embodim |