Wellbore primary barrier and related systems

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 & 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 & 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'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'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'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'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's interior or with extendable piston'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'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'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'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'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