PATENT ABSTRACT
A wellbore casing, including a casing section, for deployment in a subterranean wellbore. The casing section includes a pre-milled windowed opening. A liner is disposed within the casing section covering the window opening from the inside. In addition, a rigid material is disposed outside of the casing section covering the window opening. A filer is located intermediate the casing section and the liner. The liner, filler and rigid material prevent cement from affecting the window opening when the casing section is being cemented in the wellbore.

PATENT DESCRIPTION
This application is a continuation of U.S. application Ser. No. 09/305,775 filed on Apr. 16, 1999, now U.S. Pat. No. 6,283,208, 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 &#39;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 
     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. 2 is a view showing the orientation of FIGS. 2 a  and  2   b.    
     FIGS. 2 a  and  2   b  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- a  and  3 A- b;    
     FIGS. 3A- a  and  3 A- b  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- a  and  3 B- b;    
     FIGS. 3B- a  and  3 B- b  are a section along line  3 B— 3 B of FIG. 3A; 
     FIG. 4A is a view showing the orientation of FIGS. 4A-a and  4 A-b; 
     FIGS. 4A- a  and  4 A- b  are a front elevation view, partly cutaway, of a whipstock of another toolguide; 
     FIG. 4B is a view showing the orientation of FIGS. 4B- a  and  4 B- b;    
     FIGS. 4B- a  and  4 B- b  are a section along line  4 B- 4 B of FIG. 4A; 
     FIGS. 4C and 4D are sectional views along line  4 C- 4 C and  4 D- 4 D, respectively, of FIG. 4B; 
     FIG. 4E is a bottom end view of FIG. 4A; 
     FIG. 4F is a top end view of FIG. 4A; 
     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  5 C- 5 C of FIG. 5A; 
     FIG. 6A is a view showing the orientation of FIGS. 6A a  and  6 A b;    
     FIGS. 6A a  and  6 A b  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 a  and  6 B b;    
     FIGS. 6B a  and  6 B b  are longitudinal sections along another lower section of a toolguide; 
     FIG. 7 is a view showing the orientation of FIGS. 7A to  7 C; 
     FIGS. 7A to  7 C are longitudinal sections along a casing section for a deviated wellbore junction; 
     FIG. 8 is a view showing the orientation of FIGS. 13 a  and  13   b;    
     FIGS. 8 a  and  8   b  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. 13 is a view showing the orientation of FIGS. 13 a  and  13   b;    
     FIGS. 13 a  and  13   b  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 C—C 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  16   a  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  16   a  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  16   a . 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  16   a.    
     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  16   a . 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  16   a  are aligned along the casing. 
     A liner  34  is positioned in casing  8  and seals  36   a  and  36   b  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  36   b  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  16   a  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  36   a ,  36   b , are filled with cement. To further prevent entry of materials into slots  16   a ,  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  36   a  and the cement and fillers in spaces  43 . As the cement fills the casing annulus, it is prevented from entering slot  16   a  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  36   a ,  36   b , 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 and 3B and FIGS. 4A to  4 F, 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°/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 FIG.  3 B). 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 ½ 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  4 F, 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.  3 B. 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 ½″ 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.  5 A. 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  77   a.    
     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  16   a  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  98   a ,  98   b . Arms  98   a ,  98   b  are formed to be extendable through bore  73  on either side of latch  20 . Arms  98   a ,  98   b  are generally wedge-shaped to permit rotation of mandrel  72  in bore  73 . As mandrel rotates, arms  98   a ,  98   b  are driven from a position in which they do not restrict movement of the latch in the channel to a position in which arm  98   a  abuts against shoulder  99  of latch  20  and prevents it from moving back into channel  88 . In this way arm  98   a  can be moved to act as a lock against retraction of latch  20  into channel  88 . Arm  98   b  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  16   a  in casing section  8 . The toolguide is hoisted and rotated slowly, until latch  20  is located in slot  16   a . 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.  5 B). During rotation of the mandrel, arms  98   a ,  98   b  will be rotated so that arm  98   a  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  16   a . 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  98   a  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 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 ′. 
     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  177   a  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  179   a  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  16   a  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 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 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 . 
     The lower sections of FIGS. 6A and 6B are useful with a casing section  224  as shown in FIGS. 7A to  7 C. 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.  7 A and casing sections can be connected above casing section  224  by threaded connection to box end  224 ″ in FIG.  7 C. 
     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. 6 b ) so that dogs  208  can be accommodated in profile  230 . Casing section  224  also includes a latch receiving slot  16   a  formed a selected distance below and a selected radial orientation from window  112 . Preferably, latch receiving slot  16   a  is positioned directly below the window for ease of manufacture. Latch receiving slot  16   a  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  177   a . 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  16   a  so that when dogs  208  are located in profile  230 , latch  20 ′ will be at the same position along the casing as the slot  16   a . Thus, by rotation of the tool, latch  20 ′ can drop into slot  16   a . 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  177   a  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  7 C. 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.  4 A. 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  305   a  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.  4 A. 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  316   a ,  316   b.    
     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  123   a ,  123   b  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  125   a  and  125   a   1  and a ramped portion  125   b  therebetween to facilitate movement of key  121  between slots  125   a ,  125   a   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  125   a  and a second position at locking slot  125   a   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  7 C, 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  125   a ,  125   a   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 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  125   a  or  125   a   1  into which the key is locked. The shifting tool then rotates sleeve  123  within groove  119 . 
     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. 
     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 . 
     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. 
     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. 
     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. 
     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  454   a ,  454   b  are mounted in the body to be moveable radially inwardly and outwardly between a retracted position (i.e.  454   a ′) and an extended position (i.e.  454   b ′). In the extended position, the slips  454   a ,  454   b  are selected to frictionally engage against the sleeve with sufficient force to permit lifting and rotating of the sleeve. 
     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  454   a  are selected to enhance frictional engagement to provide for longitudinal movement (ie. lifting) of the sleeve and slips  454   b  are selected to enhance frictional engagement to provide for rotational movement of the sleeve. In particular, slips  454   a  include elongate teeth  456   a  formed orthogonal to the long axis  452   x  of the body  452  and slips  454   b  include elongate teeth  456   b  formed substantially parallel to long axis  452   x . Preferably the teeth  456   a ,  456   b  are formed with leading edges formed to define acute angle so that they exhibit enhanced frictional engagement in one direction. 
     Sleeve engaging slips  454   a ,  454   b  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  454   a ,  454   b  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  452   a  by a plug  458   b . Body  452  is connected at opposite end  452   b  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 . 
     Slips  454   a ,  454   b  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  454   a ,  454   b . 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  454   a ,  454   b  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  454   a ,  454   b  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. 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  454   a  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  454   b.    
     As noted above, the slips  454   a ,  454   b  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  454   a ,  454   b  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. 
     To assist in the pressurization of the bore, a check valve  468  is provided adjacent and  452   b , 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  454   a ,  454   b , 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  458   b  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  458   b  bursts allowing equalization between the bore pressure and the pressure about the tool. 
     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. 
     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  223   a ,  223   b  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  225   a ,  225   a ′ and  225   a ″ 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  225   a  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  225   a ′ and opening  129  is disposed over the casing window opening. The third position is the one in which the key is locked into slot  225   a ″ 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. 
     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. 
     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. 
     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 . 
     Tieback hanger  117 ′ is intended to be used with a casing section, such as that shown in FIGS. 7A to  7 C and in FIG.  13 . The casing section includes a wall  256   a  extending out into window  112  adjacent the top thereof and another wall  256   b  extending out at the bottom of the window. Walls  256   a ,  256   b  provide surfaces against which flanges  252  can latch. Walls  256   a ,  256   b  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. 
     Walls  256   a , 256   b  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. 
     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. 
     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. 
     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 . 
     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. 
     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.  6 A. 
     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. 
     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 ′. 
     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. 
     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 . 
     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&#39;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. 
     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. 
     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. 
     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. 
     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. 
     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 . 
     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  19 B 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. 
     Tieback hanger  500  is intended to be used with a casing  502 , such as that shown in FIGS. 17 to  17 B, 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. 
     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. 
     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. 
     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. 
     In one embodiment, the distance d1 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. 
     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. 
     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. 
     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  7 C, can be rotated over the window opening  504 . 
     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.