Patent Publication Number: US-6209636-B1

Title: Wellbore primary barrier and related systems

Description:
RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. application Ser. No. 09/183,943 filed Oct. 3, 1998 and of Patent Cooperation Treaty Application No. PCT/NO98/00037 filed Feb. 3, 1998, both of which are incorporated fully herein for all purposes. 
     This is a continuation-in-part of U.S. application Ser. No. 08/962,162 filed Oct. 31, 1997 entitled “Wellbore Mills and Methods” now U.S. Pat. No. 6,024,168 which is a continuation-in-part of U.S. application Ser. No. 08/752,359 filed Nov. 19, 1996 entitled “Multi-Face Whipstock With Sacrificial Face Element” now U.S. Pat. No. 5,787,978 and of U.S. application Ser. No. 08/590,747 filed Jan. 24, 1996 entitled “Wellbore Milling Guide.” U.S. application Ser. No. 08/590,747 is a continuation-in-part of U.S. Ser. Nos. 08/414,201 filed Mar. 31, 1995 now U.S. Pat. No. 5,531,271; 08/300,917 filed Sep. 6, 1994; now U.S. Pat. No. 5,425,417; 08/225,384 filed Apr. 4, 1994 now U.S. Pat. No. 5,409,060; 08/119,813 filed Sep. 10, 1993 now U.S. Pat. No. 5,452,759; 08,210,697 filed Mar. 18, 1994 now U.S. Pat. No. 5,429,187. U.S. application Ser. No. 08/752,359 is a continuation-in-part of U.S. Pat. Nos. 5,620,051 issued Jun. 3, 1996 and 5,522,461 issued Mar. 31, 1995; and of U.S. application Ser. No. 08/542,439 filed Oct. 12, 1995. 
     This is a continuation-in-part of pending U.S. application Ser. No. 08/790,543 which was filed Jan. 30, 1997 entitled “Wellbore Milling &amp; Drilling” which is a continuation-in-part of pending U.S. application Ser. No. 08/673,791 filed on Jun. 27, 1996 entitled “Wellbore Securement System, ” which is a continuation-in-part of U.S. application Ser. No. 08/210,697 filed on Mar. 18, 1994 entitled “Milling Tool &amp; Operations” now U.S. Pat. No. 5,429,187 issued Jul. 4, 1995 and is a division of application Ser. No. 414,201 filed on Mar. 31, 1995 entitled “Whipstock Side Support” now U.S. Pat. No. 5,531,271 issued Jul. 2, 1996, which is a continuation-in-part of U.S. application Ser. No. 08/300,917, filed on Sep. 6, 1994 entitled “Wellbore Tool Setting System” now U.S. Pat. No. 5,425,417 issued Jun. 20, 1995 which is a continuation-in-part of U.S. application Ser. No. 08/225,384, filed on Apr. 4, 1994 entitled “Wellbore Tool Orientation,” now U.S. Pat. No. 5,409,060 issued on Apr. 25, 1995 which is a continuation-in-part of U.S. application Ser. No. 08/119,813 filed on Sep. 10, 1993 entitled “Whipstock System” now U.S. Pat. No. 5,452,759 issued on Sep. 26, 1995. This is a continuation-in-part of U.S. application Ser. No. 08/642,118 filed May 20, 1996 entitled “Wellbore Milling System” and of U.S. application Ser. No. 08/752,359 filed Nov. 19, 1996 entitled “Multi-Face Whipstock With Sacrificial Face Element” which is a continuation-in-part of pending U.S. application Ser. No. 08/655,087 filed Jun. 3, 1996 entitled “Whipstock” which is a division of U.S. application Ser. No. 08/414,338 filed Mar. 31, 1995 entitled “Mill Valve” issued as U.S. Pat. No. 5,522,461 on Jun. 4, 1996, and a continuation-in-part of U.S. application Ser. No. 08/542,439 filed Oct. 12, 1995 entitled “Starting Mill and Operations.” All applications cited above are co-owned with the present invention and incorporated herein in their entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related to wellbore operations and, in certain particular aspects, to systems for providing primary barriers in wellbores and temperature compensation for fluid actuated apparatuses. 
     2. Description of Related Art 
     Often in a wellbore or within a tubular member in a wellbore it is desirable to have an effective sealing barrier between an upper portion of the wellbore or tubular and a lower portion thereof. A variety of prior art bridge plugs and cement systems provide barriers in wellbores and tubulars. Such a barrier is, preferably, impervious to fluids in the wellbore or tubular; unaffected by temperatures encountered in the wellbore or tubular; and strong enough and sufficiently securely emplaced to withstand forces thereon, e.g. by a dropped tool or piece of equipment. 
     Prior art fluid set bridge plugs can burst or deform when subjected to unusually high temperatures and may deform or shrink when subjected to unusually low temperatures - either of which temperature changes can impair their proper functioning. 
     FIG. 1 shows a typical prior art cement system in which cement C has been emplaced through a bull plug and hardened above and below an inflated packer P. The cement below the packer has sealed off a lower set of perforations R and has sealed off the interior of a casing S below an upper set of perforations T so that fluids from a formation F may flow to a production string G and then to surface collection equipment. Installation of a system as shown in FIG. 1 is a complex, expensive, time-consuming job. 
     Typical inflatable packers and other wellbore tools and apparatuses operated by fluids can be adversely affected when the temperature of actuating fluid changes or when the temperature of fluids contacting the apparatus changes. Also various fluid actuated anchor devices can be adversely affected by such temperature changes. 
     There has long been a need for an effective and efficient wellbore barrier that is not adversely affected by temperature changes within the wellbore or within a tubular member within which the barrier is emplaced. There has long been a need for such a barrier that serves as a primary barrier which is so securely emplaced that certain forces encountered in a wellbore are insufficient to dislodge, penetrate, or move the barrier. There has long been a need for temperature-compensated apparatus for wellbore operations which include a temperature compensating system so that temperature changes encountered in a wellbore do not adversely affect operation of the apparatuses. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention, in certain aspects, provides a wellbore apparatus that is actuated by fluid under pressure or in which certain mechanisms are moved or held in position, selectively or otherwise, by fluid (hydraulic or pneumatic) under pressure in combination with a temperature compensating system that accounts for and counters the effects of temperature changes imposed on the wellbore apparatus while it is positioned within a wellbore or within a tubular member of a tubular string within a wellbore and, in one aspect, maintains constant or nearly constant internal fluid pressure in the mechanism. Such an apparatus is, in one aspect, a “through-tubing” apparatus. 
     In one particular aspect an inflatable packer system is provided that has a temperature compensating system that maintains the temperature of fluid within the packer at a desired level so that the packer does not inadvertently deflate. In another aspect such a packer system includes a wellbore anchor apparatus (such as any known wellbore anchor or anchor device, mechanically and/or hydraulically actuated, regular set or through-tubing). In one aspect, the anchor is set prior to packer inflation which may greatly facilitate packer inflation in a wellbore with fluid cross flow. In another aspect (with or without the anchor apparatus) a diverter or whipstock is connected above the packer (any known whipstock or diverter; orientable; solid, hollow-filled, or hollow; through-tubing; and/or retrievable). Such a whipstock may be set either on the low side or high side of casing. 
     Mill guide systems as disclosed in U.S. Pat. No. 5,727,629 issued Mar. 17, 1998 and in pending U.S. application Ser. No. 08/962,162 filed Oct. 31, 1997 are anchored in a wellbore or in a tubular with an anchor device. A mill guide system according to the present invention includes an anchor apparatus as disclosed herein with a thermal compensator as disclosed herein. In one aspect such a thermal compensator has a hollow piston with differential piston surfaces mounted concentrically in a chamber around the mill guide. 
     In another embodiment of the present invention a packer system is provided that includes an inflatable packer and a wellbore anchor apparatus (as discussed in the preceding paragraph) including, but not limited to hydraulically (or pneumatically) selectively settable anchor devices for wellbore tools as disclosed in the prior art, e.g. but not limited to, as used to anchor a whipstock. 
     Systems as described herein may be run down hole in a wellbore on: a typical tubular string, e.g. but not limited to, a string of tubing or casing; on coiled tubing; on a wireline (e.g. with a selectively actuatable pump using either wellbore fluid or a fluid charge stored therein to actuate a fluid actuated apparatus or apparatuses, which apparatus(es) in one aspect are selectively releasable from the pump and wireline); pipe; and/or snubbing pipe. Sealing apparatus as disclosed here may be used to close off a wellbore, casing in a main or lateral wellbore, and/or a liner in a main or lateral wellbore—and such sealing apparatus may be selectively deflatable and/or retrievable and, in one aspect, may be used with anchor apparatus and/or temperature compensating apparatus as disclosed herein. Systems as disclosed herein may be set in perforated casing. Systems as disclosed herein may be used in milling a window in perforated casing. In one aspect a system as disclosed herein that includes an anchor, a sealing apparatus such as an inflatable sealing packer or sealing plug, and whipstock apparatus is no more than about 10 meters in length. 
     It is also within the scope of this invention to provide a fluid powered and/or selectively actuated wellbore anchor apparatus with a temperature compensating system that maintains fluid temperature within the anchor apparatus at a desired level or within a desired range so that temperature changes imposed on the anchor apparatus do not adversely affect its operation or result in its deactivation and unwanted movement. It is to be understood that any anchor apparatus disclosed herein may be used to anchor in a wellbore or within a tubular in a wellbore. 
     What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, other objects and purposes will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide a fluid activated and/or powered wellbore apparatus (or apparatuses) with a temperature compensator; 
     Such an apparatus which is a packer or an anchor; and 
     Such an apparatus that includes a packer, an anchor, and, in one aspect, a whipstock or diverter; 
     It is also, therefore, an object of at least certain preferred embodiments of the present invention to provide an inflatable packer with a wellbore anchor device or apparatus; and to provide new, useful, unique, efficient, nonobvious devices and methods for selective re-entry of multi-lateral bores branching from a main wellbore. 
     Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
     The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one skilled in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments. 
     FIG. 1 is a side schematic view of a prior art system. 
     FIG. 2 is a side cross-section view of a system according to the present invention. 
     FIG. 3 is a side cross-section view of a system according to the present invention. 
     FIG. 4 is a side cross-section view of a system according to the present invention. 
     FIG. 5 is a side cross-section view of a system according to the present invention. 
     FIG. 6 is a side cross-section view of a system according to the present invention. 
     FIGS. 7A and 7B are side cross-section views of a system according to the present invention. 
     FIGS. 8A-8C are side cross-section views of temperature compensating systems according to the present invention. 
     FIG. 8D is an enlargement of part of the system of FIG.  8 B. 
     FIG. 9 is a side cross-section view of a system according to the present invention. 
     FIGS. 10A-10D are side cross-section views of systems according to the present invention. 
     FIG. 11 is a schematic view of a prior art multi-lateral wellbore selective re-entry system. 
     FIGS. 12A-12C are schematic side views of systems according to the present invention. 
     FIG. 13A is a side view in cross-section of a mill guide according to the present invention anchored in a wellbore casing. FIG. 13B is a top end cross-sectional view of the mill guide and casing of FIG.  13 A. FIG. 13C is a side cross-sectional view of an operation with the mill guide of FIG.  13 A. FIG. 13D is a side view, partially in cross-section of a mill guide system according to the present invention. FIG. 13E is a side view in cross-section of a mill guide according to the present invention. FIG. 13F is a side view in cross-section of a mill system according to the present invention with a mill guide. 
     FIG. 14 is a side schematic view of a wellbore mill system according to the present invention. 
     FIG. 15A is a side view in cross-section of a whipstock according to the present invention. FIGS. 15B and 15C are partial views of the whipstock of FIG.  15 A. FIG. 15D is a cross-section view along line  15 D— 15 D of FIG.  15 A. 
     FIGS. 16A and 16B are side views in cross-section of a system according to the present invention. 
     FIG. 17A is a side view in cross section of a system according to the present invention. FIG. 17B is an enlargement of part of the system of FIG.  17 A. 
     FIGS. 18 is a side cross-section view of a mill system according to the present invention. 
    
    
     DESCRIPTION OF EMBODIMENTS PREFERRED AT THE TIME OF FILING FOR THIS PATENT 
     FIG. 2 shows a system  10  according to the present invention in a casing  12  within an earth wellbore (not shown) that extends up to the earth surface (not shown). An inflatable packer  14  is connected to a tubular string  16  which extends up to the earth surface. A temperature compensator  18  is connected to and below the inflatable packer  14 . The inflatable packer  14  may be any known suitable inflatable wellbore packer or inflatable plug. 
     FIG. 3 shows a system  20  according to the present invention with a fluid operated anchor apparatus  22  connected to a tubular string  26  that extends upwardly within casing  24  to the earth&#39;s surface (not shown). The anchor apparatus  22  secures the system  20  in place in the casing  24 . In one aspect, the anchor apparatus  22  is selectively actuatable and selectively disengageable from the casing. A temperature compensator  28  is connected to and below the anchor apparatus  22 . (It is within the scope of this invention for any temperature compensator disclosed herein to be above or adjacent any apparatus.) The anchor apparatus  22  may be any known fluid operated wellbore anchor apparatus, including, but not limited to anchor devices with extendable slips for engaging a casing&#39;s interior or with extendable piston&#39;s for doing so. In certain aspects it is preferred that the anchor apparatus be disposed substantially symmetrically in the casing as viewed from above. As shown, selectively extendable members  22   a  have been extended and secure the system in the casing  24 . 
     FIG. 4 shows a system  30  with an anchor apparatus  32  (like the anchor apparatus  22 ) connected to and above an inflatable packer  34  (like the packer  14 ). The anchor apparatus  32  (not yet activated as shown in FIG. 4) is connected to a tubular string  37  that extends up to the earth surface (not shown) within a casing  36  in a wellbore  38  that extends up to the earth surface. The string  37  (as may other strings disclosed herein) may be a hollow tubular string, coiled tubing, or a wireline. 
     FIG. 5 shows a system  40  with an anchor apparatus  42  not yet selectively actuated, (like the anchor apparatuses  22 ,  32 ) connected to a tubular string  47  that extends up to the earth surface (not shown) in casing  46  within a wellbore (not shown, like wellbore  38 ). An inflatable packer  44  (like the packer  14 ) is connected to and below the anchor apparatus  42  and a thermal compensator  48  is connected to and below the inflatable packer  44 . With any system herein component parts (e.g. anchors, packers, compensators may be interconnected with suitable couplings, subs, or connectors and/or to each other. 
     FIG. 6 shows a system  60  according to the present invention with an inflatable packer  64  (like the packer  14 ) connected to and below an anchor apparatus  62  (like the anchor apparatus  22 ) which is anchored within a casing  68  in an earth wellbore (not shown), the casing extending up to the earth&#39;s surface. A whipstock  67  is connected to the anchor apparatus  62  and may be any known suitable whipstock or diverter used in wellbore operations, including, but not limited to a retrievable or non-retrievable; solid, hollow-filled, or hollow whipstock; and/or a through-tubing whipstock (as may be any whipstock disclosed herein). 
     The packers shown in FIGS.  2  and  4 - 6  are shown uninflated. Each packer is selectively inflatable as is well known to one skilled in the art. The systems of FIGS. 3-6 provide a primary barrier within their respective casings that is secured in place and effectively seals off the casing interior to fluid flow. The temperature compensators of FIGS. 2,  3  and  5  prevent temperature changes within the casing from resulting in bursting or deflation of the packer in each system. 
     FIGS. 7A and 7B show a system  70  according to the present invention with a temperature compensator  78  connected to and below an inflatable packer  74  (like the packer  14 ) which is connected to and below an anchor apparatus  72  (like the anchor apparatus  22 ). A whipstock  77  (like the whipstock  67 ) is movably (e.g. tiltably) connected to and above the anchor apparatus  72 . 
     As shown in FIG. 7B, the anchor apparatus  72  has been selectively actuated from the surface and moved by extendable members  72   a  projecting out of a side of the anchor apparatus to one side of the casing  75  and a top  76  of the whipstock  77  has tilted against an opposite side of the casing  75 . The casing  75  extends up within a wellbore (not shown) to the earth&#39;s surface. As shown in FIG. 7B the packer  74  has been selectively inflated to seal off flow through the casing  75 . In one particular aspect the anchor apparatus has as extendable members a main piston that projects out from the anchor apparatus to contact the casing and move the bottom of the whipstock against one side of the casing, providing significant anchoring force. Two other projecting pistons, each set about 90° apart from the main piston and contacting the casing provide stability and some anchoring force. Such an anchor apparatus will function properly in oval or uncemented casing. 
     FIGS. 8A-8D show temperature compensating systems according to the present invention that include one or more packers or downhole seals of the inflatable balloon type, formed to sealingly bear, in use, by its outer circumferential surface on, for example, the inner shell surface of a tubular or production riser. To prevent the pressure inside the inflated seal, because of temperature variations, getting so high that the packer seal bursts, or so low that the seal loosens and loses or reduces its effect, the seal has thereto connected a compensator which is arranged to adjust the internal pressure of the inflated seal in relation to the pressure of the surroundings on the underside/downstream of the seal, which will thus make a true reference pressure for the internal pressure of the seal and compensate for temperature differentials encountered in the wellbore that could adversely affect the plug, packer, or seal. By increasing pressure inside the inflated seal the ambient pressure permits a leakage of the liquid/gaseous inflating medium of the seal to maintain a largely constant internal pressure in the seal, whereas by a falling pressure inside the seal, the ambient pressure causes it to rise by supplying additional inflating medium from a reservoir to maintain a pressure desired for the seal, plug, or packer. 
     FIG. 8A shows a system  110  according to the present invention which includes a wellbore apparatus  111  which may be any fluid activated and/or fluid powered wellbore tool, device or apparatus. As shown, the wellbore apparatus  111  is an inflatable packer for use in a well  112  in connection with oil/gas production. The apparatus  111  is arranged to work at well pressure and is formed to enable itself to be set and kept in position, sealingly bearing against the adjacent tube shell surface, for example the inner surface of a casing or production riser  113  by means of compressive forces which are subject to variations compensated for by means of a compensator  116 . The compensator  116  is connected to and in fluid communication with the apparatus  111  and has a cylinder  120  in which is displaceably positioned a reciprocatingly slidable piston  122 , which is brought to move on the occurrence of compensatable temperature variations. The apparatus  111 , which is in this case an inflatable packer, is in fluid communication with the cylinder  120 , and a piston  122  has a first piston surface  134  which is influenced by the pressure inside the packer  111 , and a second piston surface  130  facing the opposite direction which is influenced by the pressure in the well. The two piston surfaces have mutually different areas, the pressure compensator  116  being arranged to regulate, on the basis of this difference in piston surface area, the internal pressure in the inflated packer  111  in relation to the ambient pressure (well pressure) effective downstream of the packer  111  and thus constituting a reference pressure for the internal pressure of the packer  111 . Such a system is described in detail in pending PCT application PCT/NO98/00037 incorporated fully herein for all purposes and a copy of which is appended hereto as part hereof. 
     Although they are not equivalent, it is within the scope of this invention to use, instead of the particular thermal compensators disclosed in the specific embodiments described herein, a spring loaded thermal compensator or a gas charged thermal compensator. 
     Reference is now made to an embodiment  160  according to FIGS. 8A and 8B, which is different from the described embodiment according to FIG. 8A in (a) the configuration of the piston device, (b) a central through passage for the transportation of desired fluid (oil) from an underlying formation zone through an above lying formation zone producing undesired fluid (water), and (c) the use of two opposite downhole seals (only one of these identical seals is shown) axially spaced. In this embodiment of FIGS. 8B and 8C a central, tubular piston rod  134   a  is formed with an annular piston  136  having a first piston surface  136 ′ (see FIG. 8D) which faces an inflated seal or packer  161 , and which has a considerably smaller surface area than a second piston surface  136 ″ which faces a free end  127 ′ of a compensator  16 . The surface area proportion may for example be (but is not limited to) 1:6, such as in the embodiment of FIG.  8 A. 
     According to FIGS. 8B and 8C an upper end portion of the central, tubular piston rod  134   a  is in axially displaceable engagement with a lower tube section  138 ′ of a concentric inner tube  138  of a first piston of an upper cylinder housing  120 , said inner tube  138  being connected end-to-end to a coaxial tube  140  which has a bore  140 ′ extending through the inflated seal  161 . Said tube section  138 ′ which has a comparatively large diameter and in a tightening manner grips around the piston rod  134   a,  is surrounded, like the rest of this tube  138 , by longitudinal channels  124 ,  124 ′ (alternatively by a concentric annulus) which, according to FIG. 8B, are continued by a cylinder bore  142  extending downwards, the cylindrical bore  142  being continued with the same radius as that of a coaxial cylinder bore  144  of the lower cylindrical piston housing  127 . FIG. 8C shows a limit position for the piston rod/piston  134   a / 136  in said upper cylindrical housing. 
     In this embodiment in which, in one aspect, are used two comparatively widely spaced, symmetrically placed, inflated downhole packers or seals  161 , the lower cylindrical piston housing  127  shown is provided, at a suitable point of its axial length, with mainly radially directed ports  146 ,  146 ′, the cylinder bore  144  immediately below the ports  146 ,  146 ′ being provided with a radially inward annular flange with a seal  148  tightening around the tubular piston rod  134   a.  The free end  127 ′ has a bore  132 . 
     FIG. 9 shows a system  90  according to the present invention with a thermal compensator  98  connected to and below an inflatable packer  94  (like the packer  14 ) which is connected to and below an anchor apparatus  92 . The anchor apparatus  92  is an hydraulic hold-down anchor apparatus as disclosed in pending U.S. application Ser. No. 09/183,943 filed Oct. 31, 1998 and co-owned with the present invention. The anchor apparatus  92  is symmetrically centered within casing  95  that extends up in an earth wellbore (now shown) to the earth surface and is connected to a tubular string  96  that extends up to the earth surface within the casing  95 . 
     FIG. 10A shows a system  20  as in FIG. 3 with an orienting apparatus for orienting the anchor apparatus  22 . In one aspect the orienting apparatus is a measurement-while-drilling apparatus MWD. Such an MWD apparatus may be positioned anywhere in the system that is suitable for proper operation. It is shown schematically connected to the anchor apparatus  22  but, as desired, it may be spaced-apart therefrom or positioned therebelow, or below the temperature compensator. Any system disclosed herein (FIGS. 2-18) may use an orienting apparatus which, in one aspect, may be an MWD apparatus positioned anywhere as discussed above. FIG. 10B shows a system  60  as in FIG. 6 with an MWD apparatus above its anchor  62 . 
     FIG. 10C illustrates that systems according to the present invention that have a fluid actuated device may be run downhole on a wireline with a selectively actuatable pump that, in one aspect, is releasably connected to the fluid actuated device. By way of example FIG. 10C shows a system  20  as in FIG. 3 releasably connected to a pump WP on a wireline WL that extends in casing  24  to the earth&#39;s surface. Selectively actuation of the pump forces wellbore fluid and/or a fluid charge releasably stored within the pump to the anchor apparatus  22  to extend the projecting members  22   a  to anchor the system in the casing  24 . FIG. 10D shows a system  40  as in FIG. 5 on a wireline WL with a pump WP like the wireline and pump of FIG.  10 C. 
     FIG. 11 shows a prior art multi-lateral wellbore selective reentry system RS which has a retrievable whipstock anchored in casing with a prior art wellbore anchor system and a large ID mechanically set packer for sealing off the casing. A main parent wellbore has three lateral wellbores (or “sidetracks”) branching off from it. The system RS makes possible numerous sidetracks from the parent wellbore, while providing the ability to mill lateral windows in close proximity to one another. Any specific sidetracked lateral can be re-entered at any time, with simultaneous parent wellbore accessibility. 
     FIG. 12A shows a main wellbore  170  with lateral wellbores  171 ,  172 , and  173  extending out therefrom. The main wellbore is cased with casing  174  and the lateral wellbores have liners  175 ,  176 , and  177 . A system  30   a  (like the system  30 ) has been anchored in the liner  175  to close off lateral wellbore  171 . A system  30   b  (like the system  30 ) has been anchored in the liner  176  to close off lateral wellbore  172 . A system  40   a  (like the system  40 ) has been anchored in liner  177  to close off lateral wellbore  173 . The sealing packer in the system in each liner has been activated to seal off its respective liner to fluid flow. In one aspect each system (two of them, or all systems) may be selectively re-accessed to deactivate the anchor, and deflate the packer to re-establish communication between a lateral wellbore and the main wellbore. Optionally, the main wellbore may be closed off (e.g. with a system as in FIGS. 2,  4 ,  5 ,  6 ,  7 A,  8 A,  8 B,  9 ,  10 B or  10 D) and/or one of the laterals may be opened up and/or a new lateral may be drilled (following milling of a window for the new lateral e.g. with a whipstock system and/or mill system as disclosed herein). 
     FIG. 12B shows a system  70   a  according to the present invention which is like the system  70 , FIG.  7 A. The system  70   a  is a “through tubing” system that has been inserted through tubing  181  that extends from the earth surface or from a hanger from another string in an earth wellbore  182 . A tubular string  183  with a larger diameter than the tubing  181  extends down beyond the lower end of the tubing  181 . Three lined lateral wellbores  184 ,  185 ,  186  branch off from the main wellbore  182 . Systems  30   e,    30   f,  (both like the system  30 , FIG. 4) and  40   c  (like the system  40 , FIG. 5) close off the lateral wellbores. The system  70   a  has been selectively anchored with its whipstock  70   b  oriented so that it can divert a mill or mill drill to create a window through the casing and/or start a new lateral wellbore at a desired location. Any or all of the components of the system  70   a  may be retrievable. 
     It is within the scope of this invention for the anchor, packer, and thermal compensator of the system  70   a  to be installed in a first trip into the main wellbore  182  and then to orient and install the whipstock on the anchor in a second trip. Optionally the mill or mill-drill (not shown) can be releasably attached to the whipstock of the system  70   a  so that another trip to introduce the mill or mill-drill is not necessary. 
     FIG. 12C schematically illustrates a wellbore combination as in FIG. 12A but with a casing CS in a main wellbore (not shown, like the main wellbore  174 , FIG. 12A) closed off beneath liner LR in a lateral wellbore (not shown, like the lateral wellbore  173 , FIG. 12A) with a system  40   b  (like the system  40 ). The string that was used to install the system  40   b  (like the string  47  or coiled tubing, wireline, etc.) has been released from the system  40   b  and removed from the main wellbore. Systems  30   c  and  30   d  close off liners LN and LS, respectively (like liners  175 ,  176 , FIG. 12A) in lateral wellbores (not shown, like wellbores  171 ,  172 , FIG.  12 A). 
     FIGS. 13A and 13B show a mill guide  270  according to the present invention with a hollow cylindrical body  279  having a bore  278  therethrough, an open top end  277  and an open bottom end  276 . The mill guide  270  is disposed in a piece of casing  275  which is part of a string of casing (not shown) in a wellbore in the earth. An anchor  274  (or anchors) holds the mill guide  270  in place at a desired location in the casing with an opening  273  of the mill guide&#39;s bottom end  276  disposed and oriented so that a mill passing through the mill guide  270  will mill a desired area of the casing, creating a desired hole, slot, opening, or window. The bottom end  276  of the mill guide  270  is formed or cut to have a desired shape  272 . This shape  272  may be made to correspond to a curved portion  271  of the casing  275 . 
     As shown in FIG. 13C, a mill  281  on a string of drill pipe  282  has been introduced through the casing  275  and the mill guide  270  to contact the casing  275  and begin to mill a hole therethrough. A body  283  of the mill  281  has a length such that at least about a fourth of the desired opening is milled (and in other aspects substantially all of the desired opening) while the mill body  283  remains in contact with a side  280  of the bottom end  276  of the mill guide  270 , thus providing a continuous reaction support during part or substantially all of the milling. The side  280  may be the same thickness as a side  298  which is shorter than the side  280 ; or the side  280  may be thicker than the side  298 . The interior of the  30  side  280  may one or more additional layers of material thereon. Such material may also inhibit the mill from milling the side  280 . This additional material may be any desired practical thickness and may be any known suitable material, including, but not limited to, steel, carbide steel, stainless steel, known alloys, and hardfacing material. Such a layer or layers may be added by any known method (e.g., welding or hardfacing) or may be formed integrally of the side  280 . 
     FIG. 13D shows a mill guide  285  with a hollow body  286 , a top open end  296 , a bottom end point  288 , a side opening  289 , and a slanted side member  291 . A whipstock  290  disposed in a casing  292  in a wellbore  293  has a concave surface  294  which corresponds to the shape of the slanted side member  291 . The mill guide  285  is made of a strong metal, e.g. steel, so that the slanted side member  291  protects the concave surface  294  from the effects of a mill  295  on flexible pipe  299 . The whipstock  290  and the side opening  289  are positioned so that a window  287  is cut at a desired location on the casing  282 . As shown in FIG. 13D the window  287  has only been partially milled and will be completed as the mill  295  moves down the slanted side member  291 . It is within the scope of this invention for the mill guide  285  and the whipstock  290  to be connected together; to be formed integrally as one member; or for the mill guide  285  to be releasably connected to the whipstock (e.g. but not limited to, by one or more shear studs or shear lugs). In another aspect the mill guide and the whipstock are installed separately. The mills in FIGS. 13A-14 may be any mill disclosed in U.S. application Ser. No. 08/962,162, in any of its parent applications; or any suitable wellbore mill or mill systems. 
     FIG. 13E discloses a mill guide system  250  with a mill guide  251  (like the mill guide of FIG. 13A) with a fluid activated anchor (or anchors)  252  (like the anchor or anchors  274 ) and a thermal compensator  253  for maintaining a desired fluid pressure in the anchor  252 . 
     FIG. 13F discloses a system like that of FIG.  13 E and like numerals indicate like parts. A mill  254  is releasably secured to the mill guide  251  by, e.g., a shear pin  255 . The mill  254  represents, within the scope of this invention, any known suitable mill, mills or milling system. The mill  254  is connected to a rotatable wellbore string  258  that can extend from an earth surface to a location in a wellbore. Alternatively, as with any mill or mill-drill herein, a downhole motor may be used to rotate the mill or mill-drill. 
     FIG. 14 discloses a system  60   a  like the system  60 , FIG. 6 (and numerals indicate the same parts) with a mill  60   b  (like the mill  254  or its alternatives) connected to a rotatable string  60   c  like the string  258  or its alternatives). The mill  60   b  is selectively releasably secured to the whipstock  67 . A shear stud  60   d  l releasably secures the mill  60   b  to the whipstock  67 . 
     FIG. 15A-15D shows a whipstock  570  according to the present invention which has a top solid part  571  releasably connected to a hollow lower part  576 . The top solid part  571  has a pilot lug  572 , a retrieval hook hole  573 , a concave inclined surface  575  and a rail  579 . The lower hollow part  576  has an inner bore  577  shown filled with drillable filler material or cement  578 . The cement is in the tool as it is inserted into the casing. The lower hollow part  576  has a concave inclined surface  580  which lines up with the concave inclined surface  575  of the top solid part  571 . Shear screws  581  extend through holes  583  in the lower hollow part  576  and holes  582  in the top solid part  571  to releasably hold the two parts together. The rail  579  is received in a corresponding groove  574  in the lower hollow part  576  to insure correct combination of the two parts. Preferably the length of the top solid part is at least 50% of the length of the inclined portion of the concave. A whipstock  570  maybe used in any system disclosed herein. Upon completion of an operation, the top solid part is released by shearing the shear screws with an upward pull on the whipstock, making retrieval and re-use of the top solid part possible. The bottom hollow part need never leave the wellbore. 
     FIGS. 16A and 16B illustrate a whipstock  600  according to the present invention in a casing C in a wellbore. The whipstock  600  has an outer hollow tubular member  602  having a top end  603 , a bottom end  604  and a central bore  605 ; and an inner solid member  606  with a top end  607 , a bottom end  608 , a concave  609  with a concave inclined surface  610 , and a retrieval hook slot  611  in the concave  609 . The hollow tubular member  602  is secured to the casing and, while in use, the inner solid member  606  is releasably secured to the outer hollow tubular member  602 , e.g. by shear pins  612  extending from the inner solid member  606  into the outer hollow tubular member  602 . As shown in FIG. 16B, upon shearing of the pins  612  by an upward pull with a retrieval tool T, the retrieval tool T is used to remove the inner solid member  606  for re-use. 
     FIG. 17A shows a system  1010  according to the present invention having a whipstock body  1012 , a sacrificial element  1020  with two guiding faces secured to the whipstock body  1012  with bolts  1026 , filler  1028  in a recess  1030  of the body  1012 , and a plug element  1040  in a bottom  1034  of the whipstock body  1012 . 
     A top  1014  of the whipstock body  1012  extends above the sacrificial element  1020  (preferably made of readily millable material, e.g. brass, bronze, composite material, iron, cast iron, typical relatively soft bearing materials, soft steels, fiberglass, aluminum, zinc, other suitable metals, or alloys or combinations thereof) and has a sloped ramp  1038 . One-way teeth  1016  are formed in the top  1014  so that a member (not shown) with corresponding teeth may push down on the whipstock body  1012  so that exerted force is transmitted from the corresponding teeth of the member to the whipstock body  1012  and so that the teeth  1016  and the corresponding teeth on the member slide apart when pulling up on the member with sufficient force. A hole  1018  provides an opening for receiving a connector to connect the member to the whipstock body  1012 . 
     The first face  1022  of the sacrificial element  1020  is slanted so that a mill with an appropriate corresponding ramped portion contacts the first face  1022  and is directed away from the whipstock body  1012  (at an angle of between 5° to 25° and in one aspect about 15° from the central longitudinal axis of the body) e.g. to commence milling of a tubular (not shown), e.g. casing or tubing, in which the system  1010  is anchored. Any suitable known anchor device may be used. The second face  1024  is configured, sized and disposed for further direction of a mill away from the whipstock body  1012  as it mills the tubular. 
     In one aspect as a mill moves down against the sacrificial element  1020 , it mills a portion of the sacrificial element  1020  rather than milling the whipstock body  1012 . A third face  1032  includes sides or “rails” of the whipstock body  1012  which are sufficiently wide and strong to guide a mill moving downwardly adjacent the whipstock. A fourth face  1033  extends below the third face  1032 . In one aspect the fourth face  1033  is straight and the third face  1032  is a chord of a circle. The first, second, third, and fourth faces may each be straight or curved (e.g. a chord of a circle) as desired and either inclined at any desired angle in a straight line away from a longitudinal axis of the body or curved as a chord of any desired circle. 
     The plug element  1040  is secured in the bottom  1034  of the whipstock body  1012 . The plug element  1040  retains the filler  1028  within the recess  1032 . Via a channel  1041  through a tube  1042  (e.g. made of readily millable material), a channel  1055  through a valve body  1056  (e.g. made of readily millable material), a channel  1072  through a body  1062 , and a sleeve  1074  in a body  1064 , fluid flow through the plug element  1040  is possible when a valve member  1058  rotates upwardly about a pivot  1060 . As shown in FIG. 17B the valve member  1058  is closing off fluid flow from above the plug element  1040  to beneath it, either due to the fact that there is little or no fluid flow and gravity holds the valve member  1058  down or the force of fluid flow from below into the channel  1072  is insufficient to overcome the weight of fluid on top of the valve member  1058 . Epoxy or some other suitable adhesive may be used to hold the body  1062 , body  1064 , and sleeve  1074  together. 
     In one particular embodiment sacrificial element  1020  is about 30 inches long (excluding the extending top part with teeth) and the blade sets of the mill  1200  are spaced apart about two feet and the nose  1240  is about 18 inches from its lower end to the first set of blades  1231 . With such a mill a completed initial window is about  60  inches long. It is within the scope of certain preferred embodiments of this invention for the initial window through the casing to be two, three, four, five, six, seven or more feet long. 
     FIG. 18 shows a mill system with a window mill  1250  for use to enlarge the window made by a mill. The window mill  1250  has a body with a fluid flow channel from top to bottom and jet ports to assist in the removal of cuttings and debris. A plurality of blades present a smooth finished surface which moves along what is left of the sacrificial element  1020  (e.g. one, two, three up to about twelve to fourteen inches) and then on the filler  1028  and the edges of whipstock body that define the recess  1030  with little or no milling of the filler  1028  and of the edges of the whipstock body  1012  which define the recess  1030 . Lower ends of the blades and a lower portion of the body are dressed with milling material  1260  (e.g. but not limited to known milling matrix material and/or known milling/cutting inserts applied in any known way, in any known combination, and in any known pattern or array). 
     In one aspect the lower end of the body of the mill tapers inwardly an angle to inhibit or prevent the window mill lower end from contacting and milling the filler  1028  and whipstock body  1012 . 
     In one method according to the present invention a mill (such as the window mill  1250 ) mills down the whipstock, milling a window. Following completion of the desired window in the casing and removal of the window mill, a variety of sidetracking operations may be conducted through the resulting window (and, in some aspects, in and through the partial lateral wellbore milled out by the mill as it progressed out from the casing). In such a method the remaining portion of the whipstock is left in place and may, if desired be milled out so that the main original wellbore is again opened. In one aspect the filler  1028  and plug element  1040  are milled out to provide an open passage through the whipstock. 
     In another aspect, in the event there is a problem in the milling operation prior to completion of the window, the whipstock is removed. 
     As shown in FIG. 18, the mill  1250  has been run into a wellbore, not shown, and a window has been started in casing G. E.g. the mill is on a tubular string N of, e.g. a drill string of drill pipe to be rotated from above or to be rotated with a downhole motor as described above). The inwardly tapered portion  1260  of the body of the mill  1250  preferably does not mill the top of the whipstock body  1012  or mills it minimally. The mill  1250  proceeds down along the remainder of the sacrificial element  1020  with the mill surface  1258  holding the milling end away from the sacrificial element and directing the mill  1250  away from the body  1012  toward the casing G. The inwardly tapered portion of the mill  1250  encounters a ledge L created by the first mill, and due to the inwardly tapered portion, the mill moves outwardly with respect to the ledge L, begins to mill the casing G, and also begins to mill the remainder of the sacrificial element  1020 . The surface  1258  will continue to co-act with the resulting milled surface on the sacrificial element  1020  until the surface  1258  is no longer in contact with the sacrificial element  1258  as the mill  1250  mills down the casing G. Thus the window, (at the point at which the mill  1250  ceases contact with the sacrificial element  1020 ) that includes the initial window formed by the mill  1200  and the additional portion milled by the mill  1250  is created without the mills contacting the whipstock body  1012  or the filler  1028 . 
     Any whipstock shown in any system disclosed herein, e.g. those of FIGS. 6,  7 A,  10 B and  12 B may be hollow with filler (e.g., but not limited to, as in FIGS. 17A or  15 A) and/or retrievable (e.g., but not limited to, as in FIG.  16 B). 
     It is within the scope of this invention to provide the major components of the systems of FIGS. 2-10 and  12  as interchangeable modules and for each apparatus, e.g. a packer, to itself have a variety of interchangeable modules (e.g. different packers), depending on a particular job. 
     The present invention, therefore, provides in at least certain preferred embodiments a wellbore apparatus including anchor apparatus for anchoring the wellbore apparatus in a bore, the anchor apparatus actuated by fluid under pressure supplied thereto, and sealing apparatus selectively inflatable to close off the bore to fluid flow therethrough. Such a wellbore apparatus may have one, some, any combination of the following: wherein the anchor apparatus is connected to and in fluid communication with a tubular string for lowering the wellbore apparatus down into the bore and the fluid under pressure for actuating the anchor apparatus and the sealing apparatus is supplied through the tubular string; a pump in fluid communication with and interconnected with the anchor apparatus for pumping fluid under pressure to the anchor apparatus to actuate the anchor apparatus and to the sealing apparatus to inflate the sealing apparatus; a wellbore wireline connected to the pump for lowering the wellbore apparatus down into the bore; wherein the pump is selectively releasably connected to the anchor apparatus; wherein the pump carries a charge of fluid for pumping under pressure to supply the fluid under pressure; wherein the fluid under pressure is hydraulic fluid; wherein the anchor apparatus is releasably connected to the sealing apparatus; wherein the anchor apparatus has a plurality of selectively extendable members movable in response to the fluid under pressure to anchor the anchor apparatus in the bore; wherein the plurality of selectively extendable members are movable to concentrically anchor the anchor apparatus centered within the bore; wherein the bore is a wellbore or a bore through a tubing, e.g. but not limited to casing, tubing and liners; orienting apparatus for orienting the anchor apparatus to a desired orientation within the bore; wherein the orienting apparatus includes a measurement while drilling device; wherein the anchor apparatus is connected to coiled tubing for lowering the wellbore apparatus down into the bore; wherein the sealing apparatus is an inflatable sealing packer; whipstock apparatus connected to the anchor apparatus; orienting apparatus for orienting the whipstock to a desired orientation within the bore; wherein the orienting apparatus includes measurement while drilling apparatus; wherein the whipstock apparatus is retrievable from within the bore; wherein the whipstock apparatus is hollow and filled with drillable or millable filler material; wherein the whipstock, anchor apparatus and sealing apparatus are configured and sized for through-tubing wellbore operations; temperature compensating apparatus for maintaining a desired fluid pressure in the anchor apparatus and/or in the sealing apparatus; wherein the temperature compensating apparatus comprises a cylinder in which is displaceably positioned a reciprocatingly slidable piston which is movable in response to fluid pressure variations and which has a cavity in fluid communication with a cavity of said cylinder, the piston having a first piston surface which is influenced by the fluid pressure inside the sealing apparatus, and a second piston surface facing a direction opposite the first piston surface which second piston surface is influenced by fluid pressure in the bore, the two piston surfaces having mutually different areas, the temperature compensator arranged to regulate, on the basis of said difference in piston surface area, internal fluid pressure in the sealing apparatus in relating to ambient fluid pressure effective downstream of the sealing apparatus and thus constituting a reference pressure for the internal pressure of the sealing apparatus; wellbore milling apparatus selectively releasably connected to the whipstock apparatus; wherein the wellbore milling apparatus, whipstock apparatus, anchor apparatus and sealing apparatus are configured and sized for through-tubing wellbore operations; wherein the anchor apparatus is effective to anchor the wellbore apparatus, and the sealing apparatus is effective to seal the bore to create a primary barrier in the bore; wherein the wellbore milling apparatus is from the group consisting of: a starter mill; a window mill; a combination of a plurality of at least two mills; at least one watermelon mill; and a milling-drilling apparatus; wherein the whipstock apparatus has a channel therethrough and valve apparatus for controlling fluid flow through the channel; and/or wherein the anchor apparatus and sealing apparatus can be selectively deactivated for retrieval from the bore. 
     The present invention, therefore, provides in at least certain preferred embodiments a wellbore apparatus with sealing apparatus for selectively closing off a bore to fluid flow, the sealing apparatus inflatable by fluid under pressure, and temperature compensation apparatus for maintaining fluid under pressure in the sealing apparatus at a desired pressure. 
     The present invention, therefore, provides in at least certain preferred embodiments a wellbore apparatus having anchor apparatus for selectively anchoring in a bore the anchor apparatus actuatable by fluid under pressure, and temperature compensation apparatus for maintaining fluid under pressure in the sealing apparatus at a desired pressure. Such wellbore apparatus may include a mill guide connected to the anchor apparatus, and, in certain aspects, mill apparatus selectively releasably connected to the mill guide. 
     The present invention, therefore, provides in at least certain preferred embodiments a multi-bore wellbore system having a main wellbore cased with casing, at least one lined lateral wellbore extending from and in fluid communication with the main wellbore, at least one of the casing of the main wellbore and the at least one lined lateral wellbore closed off by a primary barrier comprising a wellbore apparatus comprising anchor apparatus for anchoring the wellbore apparatus in a bore, the anchor apparatus actuated by fluid under pressure supplied thereto, and sealing apparatus selectively inflatable to close off the bore to fluid flow therethrough; such a multi-bore wellbore system wherein tubing is above and in fluid communication with the casing of the main wellbore and the primary barrier is configured and sized for passage through the tubing into the main wellbore, the tubing smaller in diameter than diameter of the main wellbore; such a multi-bore wellbore system wherein the primary barrier is selectively deactivatable and retrievable; and/or such a multi-bore wellbore system wherein the wellbore apparatus has temperature compensating apparatus for maintaining a desired fluid pressure in the anchor apparatus and in the sealing apparatus. 
     The present invention, therefore, provides in at least certain preferred embodiments a method for closing off a bore in a well, the method including installing wellbore apparatus in the bore, the wellbore apparatus comprising anchor apparatus for anchoring the wellbore apparatus in a bore, the anchor apparatus actuated by fluid under pressure supplied thereto, and sealing apparatus interconnected with the anchor apparatus and selectively inflatable with fluid under pressure to close off the bore to fluid flow therethrough, the wellbore apparatus upon anchoring in the bore and inflation of the sealing apparatus comprising a primary barrier in the bore. 
     In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. § 102 and satisfies the conditions for patentability in § 102. The invention claimed herein is not obvious in accordance with 35 U.S.C. § 103 and satisfies the conditions for patentability in § 103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. § 112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims.