Lateral branch junction for well casing

Information

  • Patent Grant
  • 6253852
  • Patent Number
    6,253,852
  • Date Filed
    Wednesday, November 24, 1999
    24 years ago
  • Date Issued
    Tuesday, July 3, 2001
    22 years ago
  • Inventors
  • Examiners
    • Dang; Hoang
    Agents
    • Bracewell & Patterson LLP
    • Bradley; James E.
Abstract
A well casing junction connects an upper string of casing to a pair of lower or branch strings that diverge from each other. The junction tool has an upper section and a pair of branch sections that join the upper section and each other. The junction tool is collapsed for running into the well along with casing. To collapse, a force is applied to opposite sides to create identical, deep depressions in the opposite sides of the junction tool. Once in position, internal pressure forces the depressions outward to assume an expanded position. A support member locates at the junction and between the two branch sections. The support member reduces stress that occurs from moving from the collapsed to the expanded position.
Description




TECHNICAL FIELD




This invention relates in general to the construction of a lateral branch for a primary well and particularly to a junction member which sealingly connects the main borehole casing and the branch liner casing.




BACKGROUND ART




In recent years, well construction technology has yielded substantial increases in well productivity with the spread of horizontal drilling for the bottom end section of the well. Unfortunately horizontal drilled wells provide limited zonal isolation and do not always permit good completion practices regarding the independent production of different production zones. Research efforts are now concentrating on the possibility of drilling lateral branches either inclined or horizontal from a primary well to enhance further reservoir productivity. Also lateral branches open the potential of tapping several smaller size reservoirs spread around from one single well without the need to sidetrack and redrill the well when moving the production from one production zone to the next. The challenge with multilateral completion is to install a junction apparatus having adequate internal and external pressure capability without relying only on the strength of the local rock formations.




Some prior art junction apparatus designs are based on a low angle side branch casing connected to a window on the main borehole casing. Some prior proposals require in situ milling of a window or a section in the main borehole casing. Milling steel casing downhole is a difficult task. Also, while there are numerous proposals for sealing the branch liner casing to the window, improvements are needed. One design deforms a complete junction assembly to offer a diameter equal or less than the diameter of the main borehole casing and expanding it in situ to the full cylindrical shape. In that design, the junction assembly may be elastomeric or memory metal. The junction assembly is expanded within an enlarged section of the well formed after a section of the casing is milled out.




Due to the side window based connecting link between the main borehole casing and the branch outlet, all these configurations offer poor internal pressure capacity and even more limited collapse capability when the junction is located in unconsolidated or weakly consolidated formations. The poor internal pressure capability and resistance to collapsing exists even when they are fully cemented since cement does not work well in traction. It is therefore highly desirable to have a junction apparatus offering good internal pressure and collapse capability to permit a wide freedom in the location of lateral junction independent from the strength of the cementing job and/or surrounding rock formation.




SUMMARY OF INVENTION




The junction apparatus in this invention has an upper section that connects to an upper string of casing. A pair of branch sections join each other at a junction with each other and with a lower end of the upper section. Each branch connects to a lower string of casing. The apparatus is forced into a collapsed configuration prior to running into the well. While in the well, the apparatus is expanded back to an expanded configuration. While in the collapsed position, a lower portion of the upper section is deformed so that a pair of deep depressions or bights locates on the outer side, the depressions being 180 degrees apart from each other and facing in opposite directions. Also, these depressions extend into an upper portion of the branch sections.




In addition, a support member is joined to the upper section at the junction, the support member having a tail section that extends between the branch sections. The support member has arms that extend upward and join the upper section. The tail section comprises a pair of braces interconnected by a web. The web defines an inner separation wall between the two branch sections and preferably has a portion of substantially constant thickness.




While in the well, internal pressure is applied to force the depressions to disappear.




The upper section will expand in diameter. The branch sections move outward and assume a cylindrical configuration.











BRIEF DESCRIPTION OF DRAWINGS





FIG. 1

is a side elevational view illustrating a junction apparatus in accordance with this invention connected into a main string of casing and shown in a collapsed position.





FIG. 2

is a side elevational view similar to

FIG. 1

, but showing the junction apparatus expanded to a set position.





FIG. 3

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


3





3


of FIG.


1


.





FIG. 4

is a sectional view similar to

FIG. 3

, but taken along the line


4





4


of

FIG. 2

to show the apparatus expanded.





FIG. 5

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


5





5


of FIG.


1


.





FIG. 6

is a sectional view similar to

FIG. 5

, but taken along the line


6





6


of

FIG. 2

to show the apparatus expanded.





FIG. 7

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


7





7


of FIG.


1


.





FIG. 8

is a sectional view similar to

FIG. 7

, but taken along the line


8





8


of FIG. to show the apparatus expanded.





FIG. 9

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


9





9


of FIG.


1


.





FIG. 10

is a sectional view similar to

FIG. 9

, but taken along the line


10





10


of

FIG. 2

to show the junction apparatus expanded.





FIG. 11

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


11





11


of FIG.


1


.





FIG. 12

is a view similar to

FIG. 11

, but taken along the line


12





12


of

FIG. 2

to show the junction apparatus expanded.





FIG. 13

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


13





13


of FIG.


1


.





FIG. 14

is a sectional view similar to

FIG. 13

, but taken along the line


14





14


of

FIG. 2

to show the junction apparatus expanded.





FIG. 15

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


15





15


of FIG.


1


.





FIG. 16

is a sectional view similar to

FIG. 15

, but taken along the line


16





16


of

FIG. 2

to show the junction apparatus expanded.





FIG. 17

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


17





17


of FIG.


1


.





FIG. 18

is a sectional perspective view of the junction similar to

FIG. 17

, but taken along the line


18





18


of

FIG. 2

to show the junction apparatus expanded.





FIG. 19

is a sectional view of the junction apparatus of

FIG. 1

, taken along the line


19





19


of FIG.


1


.





FIG. 20

is a sectional view similar to

FIG. 19

, taken along the line


20





20


of

FIG. 2

to show the junction apparatus expanded.





FIG. 21

is a sectional view of another embodiment of the junction apparatus of

FIG. 1

, taken along the line


21





21


of FIG.


1


.





FIG. 22

is a sectional view of the junction apparatus similar to

FIG. 4

, but shown taken along the line


22





22


of

FIG. 2

to show the junction apparatus expanded.





FIG. 23

is a perspective view of a support member for the junction apparatus of FIG.


2


.





FIG. 24

is an enlarged, partially sectional view of the support member of

FIG. 23

installed in the junction apparatus of FIG.


2


.





FIG. 25

is a side elevational view of an alternate embodiment of a junction apparatus, shown in an expanded position.





FIG. 26

is a sectional view of the junction tool of

FIG. 25

, taken along the line


26





26


.





FIG. 27

is a sectional view similar to

FIG. 26

, but showing the junction tool in a collapsed position.





FIG. 28

is a sectional view of the junction tool of

FIG. 25

, taken along the line


28





28


.





FIG. 29

is a view similar to

FIG. 28

, but showing the junction tool in a collapsed position.





FIG. 30

is a sectional view of the junction tool of

FIG. 25

, taken along the line of


30





30


of FIG.


25


.





FIG. 31

is a view similar to

FIG. 40

, but showing the junction tool in a collapsed position.





FIG. 32

is a sectional view of the junction tool of

FIG. 25

, taken along the line


32





32


of FIG.


25


.











BEST MODE FOR CARRYING OUT THE INVENTION




Referring to

FIG. 1 and 2

, the junction apparatus or member


11


is connected into a string of casing and lowered into an open hole wellbore until it reaches an enlarged section of the wellbore. Junction member


11


then is pressurized by fluid pressure from the surface, causing it to move from the collapsed position in

FIG. 1

to the expanded set position of FIG.


2


. While in the expanded position, junction member


11


resembles an inverted “Y”.




Junction member


11


has an upper end section


13


that is cylindrical and connects into the string of casing that is being lowered into the wellbore. Upper end section


13


is the same diameter as the casing. An upper enlarged section


15


joins upper end section


13


, having an upper end welded to the lower end of upper end section


13


. Upper enlarged section


15


is conical, diverging in a downward direction and resulting in a greater diameter at its lower end at section line


10





10


than at its upper end. Upper enlarged section


15


has an axis


16


that is inclined relative to main casing axis


17


.




A conical lower enlarged section


19


has an upper end welded to part of the lower end of upper enlarged section


15


. In the embodiment shown, conical lower enlarged section


19


is much shorter in length than the length of upper enlarged section


15


. Conical lower enlarged section


19


converges in a downward direction, as can be seen by comparing

FIGS. 12 and 16

. Conical lower enlarged section


19


comprises one-half of a cone with a diameter at its lower end that is substantially the same as the diameter of upper end section


13


.




A conical lower enlarged section


21


also joins the lower end of upper enlarged section


15


. Conical lateral section


21


may be the same length as conical lower enlarged section


19


, but is preferably of a lesser diameter. Both conical lower enlarged section


19


and


21


are joined together via a formed section


10


which contains U-shaped portion


43


. Referring to

FIG. 12

, conical lateral section


21


forms the right half of junction member


11


at section line


12





12


, with conical lower enlarged section


19


forming the left half at that point. Conical lower enlarged section


19


and lateral section


21


are welded to each other along their inner edges


23


, the inner edges being in a plane that contains axis


16


of upper enlarged section


15


. The shape of junction member


11


at section line


12





12


is somewhat in the shape of a peanut, with a major dimension that is greater than a minor dimension.




Referring again to

FIG. 2

, a lower main section


25


of cylindrical configuration is welded to the lower end of conical lower enlarged section


19


. Lower main section


25


joins the main casing branch (not shown) extending below and is coaxial with upper end section


13


and main axis


17


. A lower lateral section


27


of cylindrical configuration is welded to the lower end of conical lateral section


21


. Lower lateral section


27


will support a string of lateral or branch casing (not shown). A drillable plug


29


is secured in lower lateral section


27


. The diameter of lower lateral section


27


is preferably slightly smaller than the diameter of lower main section


25


. Lower lateral section


27


is located on a lateral branch axis


31


that is at an acute angle relative to main casing axis


17


. Upper enlarged section axis


16


bisects axes


17


and


31


, with all three axes


16


,


17


and


31


being in a single plane.




For collapsing purposes, a plurality of forming rods


33


are secured to junction apparatus


11


. In the preferred embodiment, four forming rods


33


are employed, and they are welded to the exterior of upper enlarged section


15


. The lower ends of forming rods


33


extend into conical lower enlarged section


19


and conical lateral section


21


.




Referring to

FIGS. 2

,


23


and


24


, a support member


35


is welded to the exterior of junction member


11


at the intersection of lower main section


25


and lower lateral section


27


. These two sections join each other at the lower end of the conical lower enlarged section


19


and conical lateral section


21


. The junction resembles a crotch area with the two legs being lower main branch portion


25


and lower lateral branch portion


27


. For clarity, support member


35


is not shown in FIG.


1


.




Support member


35


is generally in the configuration of a “Y”, having two arms


37


and a leg


41


. Each arm


37


has an enlarged portion


39


on its outer end. The enlarged portions


39


are welded to the exterior of conical enlarged section


19


and conical lateral section


21


on opposite sides. Leg


41


inclines parallel to lateral branch axis


31


and is welded to an inner side of lower lateral portion


27


. The curved upper portion between arms


37


abuts against a U-shaped portion


43


formed at the crotch between conical lower enlarged section


19


and conical lateral section


21


.




Junction member


11


will first be formed and tested in the expanded configuration of FIG.


2


. Then it will be collapsed to the position shown in

FIG. 1

for passage into the well. Junction member


11


is collapsed by a folding machine (not shown) which bears against opposites sides, as shown in

FIG. 3

in the symmetrical plan, causing the side walls to deflect inward, creating depressions or bights


45


,


47




180


apart from each other. Bights


45


,


47


increase in depth in a downward direction as can be seen by comparing

FIG. 3

to FIG.


5


. The shapes of bights


45


,


47


will also change in a downward direction as can be seen by comparing

FIGS. 5

,


7


,


9


,


11


,


13


,


15


,


17


and


19


. In

FIG. 5

, forming rods


33


are welded into each of the bights


45


,


47


, preventing an excessive bending radius. There are two of the forming rods


33


in each bight


45


,


47


. The sides of forming rods


33


in each bight


45


,


47


will contact each other in the vicinity of the section line


7





7


and


9





9


.




In the collapsed position shown, the enlarged portions


39


of support member


35


are located in a plane that is substantially perpendicular to a plane that bisects each of bights


45


,


47


. Support member


35


reduces stress during the collapsing process, preventing lower main portion


25


and lower lateral portion


27


from being folded excessively. At the lower end of junction member


11


, lower main section


25


will be crescent-shaped, while lower lateral section


27


remains mostly cylindrical and substantially undeflected. A surface of revolution of junction member


11


is cylindrical when junction member


11


is collapsed and no greater at any point than the outer diameter of upper end section


13


.




During operation, junction member


11


is installed in a string of casing and lowered into a section of the well that has been previously enlarged by reaming. Junction member


11


will be run while in the collapsed position of FIG.


1


. Then, hydraulic pressure is applied to the fluid contained in the main casing and in junction member


11


. A plug (not shown) at the cement shoe (not shown) at the lower end of the main casing enables hydraulic pressure to be applied throughout the length of casing and junction member


11


. This pressure causes junction member


11


to expand to the set position with lateral leg


27


moving outward. After reaching this position, a valve will be shifted at the cement shoe to enable cement to be pumped downward, which flows through the main casing and back up an annulus surrounding the main casing.




When it is desired to drill the lateral wellbore, the operator uses a deflector (not shown) to cause the drill bit to enter lateral leg


27


. The drill bit drills out plug


29


and drills the lateral wellbore. Lateral casing of smaller diameter than the main casing will be run through lateral leg


27


into the lateral wellbore and supported by a hanger mechanism in lateral leg


27


. The lateral casing will be cemented conventionally.





FIGS. 25-34

show an alternate embodiment of junction tool


11


. Referring to

FIG. 25

, junction tool


49


has a cylindrical upper section


51


. Upper section


51


, as shown in

FIG. 26

, can be considered to have two halves or sidewall portions


51




a


,


51




b


facing in opposite directions. Sidewall portions


51




a


,


51




b


are semi-cylindrical and join each other to form a cylinder. Two branch sections


53


,


55


join upper section


51


at a junction and extend downward as shown in FIG.


25


. Each branch section


53


,


55


in this embodiment is of the same diameter. Each branch section


53


,


55


inclines relative to a longitudinal axis


57


of upper section


51


at the same angle. Branch section


53


may be considered to have an inner sidewall portion


53




a


that faces an inner sidewall portion


55




a


of branch section


55


. Similarly, branch section


53


has an outer half or sidewall portion


53




b


that faces in an opposite direction and away from outer sidewall portion


55




b


of branch section


55


.




Referring again to

FIG. 25

, a conical section


59


is located at the upper end of upper section


51


. Conical section


59


joins a cylindrical end


61


that will secure to a lower end of a string of casing. The lower end of branch section


53


secures to a string of casing while junction tool


49


is being lowered into the well. Initially, branch section


55


will be closed off with a drillable shoe


63


. Subsequently, shoe


63


is drilled out for drilling a branch well and running a casing liner into engagement with branch section


55


.




As shown in

FIG. 32

, a support member


65


locates where branch sections


53


,


55


join upper section


51


. Support member


65


is generally in the shape of a “Y”, having two upward extending arms


67


. Arms


67


are rigidly joined to the lower portion of upper section


51


. Referring to

FIG. 26

, interior portions of arms


67


will protrude inward slightly into the bore of upper section


51


.




Referring to

FIGS. 26 and 28

, junction tool


49


may be considered to have a major axis or symmetrical axis


69


. Major axis


69


bisects equally each of the branch sections


53


,


55


. A minor axis


71


, perpendicular to major axis


69


, bisects equally each of the arms


67


. As upper section


51


is cylindrical along section line


26





26


, the dimensions across upper section


51


at major axis


69


and minor axis


71


will be the same. However, when measured at section line


28





28


, the distance from outer side


53




b


to outer side


55




b


along major axis


69


is considerably greater than the distance from the outer surface of each arm


67


measured along minor axis


71


.




Referring again to

FIG. 32

, support member


65


also has a web


73


that joins each arm


67


and extends downward. The upper border end


74


of web


73


is a straight line, with stress relief notches


76


at each comer where upper end


74


joins an arm


67


with a radius


75


. While moving between the collapsed and expanded positions, arms


67


will flex at the junction with web


73


, thus the stress relief notches


76


with radius comers


75


reduce stress concentration.




Web


73


extend sideways with ribs


79


, downward from arms


67


. Ribs


79


are connected to each other by web


73


, resulting in what may be considered as a tail. By comparing

FIGS. 28 and 30

, it can be seen that at upper end


74


near section line


28





28


, web


73


will form the separating wall between branch sections


53


,


55


. The inside wall portions


53




a


,


55




a


along section line


28





28


coincide with web


73


. As one proceeds downward, however, web


73


becomes a discrete member spaced equidistant between branch sections


53


,


55


, as shown in

FIG. 30

with ribs


79


sticking out. When junction tool


49


is under operating pressure, the upper section of web


73


, where it is the separating wall between branch sections


53


,


55


, will be highly loaded while being limited in its thickness by the required drift of the branches sections


53


,


55


and might undergo plastic deformation. To spread the load over a large area, instead of concentrating the highest stresses on a single line, a constant thickness section


80


is formed in web


73


. As shown in

FIGS. 28

, constant thickness section


80


is a flat section located within the center of web


73


between braces


79


. Constant thickness section


80


is rectangular and extends downward from upper border end


74


for a selected distance.




To move junction apparatus


49


to the collapsed position, shown in

FIGS. 27

,


29


and


31


, deforming round tools (not shown)are applied on each side portion


51




a


,


51




b


along major axis


69


. These deforming tools press inward toward each other, each forming a single large depression or bight


81


. At section line


26





26


, the inner ends of bights


81


are nearly touching each other. Bights


81


face outward in opposite directions from each other. When bights


81


are created, not only will the dimension of upper section


51


shrink along major axis


69


, but it will also shrink along minor axis


71


. Also, while collapsing, the upper ends of arms


67


move toward each other, resulting in a collapsed position effective diameter


85


, shown by the dotted lines.




The same deforming tools also move outer sidewall portions


53




b


,


55




b


of branch sections


53


,


55


inward to the position shown in FIG.


29


. This results in two bights


83


that are continuations of bights


81


. Bights


83


faces in opposite directions and are located along major axis


69


. The inner surface of each bight


83


will touch web


73


at the constant thickness section


80


. The effective diameter


85


is the same as that in upper section


51


.




Referring to

FIGS. 30 and 31

, in the collapsed position, bights


83


will be in contact with the interior surface of the inner sidewall portions


53




a


,


55




a


. In the collapsed position, inner sidewall portions


53




a


,


55




a


along section line


30





30


will be flat, parallel to each other and parallel to web


73


with sticking out ribs


79


, which is equally spaced between.




Junction tool


49


will be employed the same as in the first embodiment. The operator will apply hydraulic pressure to the main casing and the junction tool


49


. The hydraulic pressure will cause junction tool


49


to move from the collapsed configuration to the expanded configuration. The operator then cements the casing and junction apparatus in the well.




The operator will then lower drill pipe through the casing and into branch section


55


to drill out plug


63


and to drill the other branch well. After drilling, casing for the other branch well will be lowered through the upper string of casing and through branch section


55


. A liner hanger will support the upper end of the second string of casing within branch section


55


.




The invention has significant advantages. Collapsing the junction tool by pressing inward on opposite sides to form symmetrical bights provides an effective means to reduce the overall diameter. The support member allows movement from the deformed position to the expanded position while reinforcing the branch junction to support high operating pressures. The stress relief radius reduces stress at the corners between the web and the arms. The constant thickness section in the web spread deformation in the highly loaded separating wall between the branches




While the invention has been shown in only two of its forms, it should be apparent to those skilled in the art that it is not so limited, but susceptible to various changes without departing from the scope of the invention.



Claims
  • 1. A well casing junction apparatus for connecting an upper string of casing to a pair of lower strings of casing, comprising:an upper section having a longitudinal axis and being adapted to be connected to the upper string of casing above the apparatus; a pair of branch sections that join each other at a junction with each other and with a lower end of the upper section and extend downward from the upper section for connection to the lower strings of casing; the apparatus being movable due to the application of internal force from a collapsed position to an expanded position in which both of the branch sections are substantially cylindrical; and wherein while in the collapsed position, a single depression is located on one side of a lower portion of the upper section and a single depression is located on an opposite side of the upper section, the depressions face in opposite directions; and while in the collapsed position, an upper portion of each of the branch sections has an outer side having a single depression that extends downward from one of the depressions from the upper section.
  • 2. The apparatus according to claim 1, wherein while in the collapsed position, an inner side of an upper portion of each of the branch sections is deformed from its configuration while expanded.
  • 3. The apparatus according to claim 1, wherein the depressions on the upper section substantially symmetrical and the depressions on the branch sections are substantially symmetrical.
  • 4. The apparatus according to claim 1, wherein while in the collapsed position, the depression on the outer side of each of the branch sections extends inward into substantial contact with an interior surface of an inner side of each of the branch sections.
  • 5. The apparatus according to claim 1, further comprising a support member joined to the upper section at the junction, having a tail section that extends between the branch sections and a pair of arms, each of the arms extending upward and joining the upper section, and wherein a line equally bisecting the arms and passing through the axis of the upper section is substantially perpendicular to a line equally bisecting each of the branch sections and passing through the axis.
  • 6. The apparatus according to claim 5, wherein the tail section comprises a pair of ribs interconnected by a web that is located in a plane that bisects the arms, the web defining an inner separation wall between the branch sections at the junction with the upper section and having an upper portion of substantially constant section sideways.
  • 7. The apparatus according to claim 5, wherein the arms move farther apart from each other when moving from the collapsed position to the expanded position.
  • 8. The apparatus according to claim 5, further comprising a stress relief notched with a radius formed at a comer of each of the arms with the tail section.
  • 9. A well casing junction apparatus for connecting an upper string of casing to a pair of lower strings of casing, comprising:an upper section having a longitudinal axis and being adapted to be connected to the upper string of casing above the apparatus, the upper section being a circular member having outer side wall portions that face laterally away and oppositely from each other; a pair of branch sections that join each other at a junction with each other and with a lower end of the upper section and extend downward from the upper section for connection to the lower strings of casing, each of the branch sections having inner side wall portions that are located adjacent to and face laterally toward each other, and outer side wall portions that face laterally away and oppositely from each other; the apparatus being movable due to the application of internal pressure from a collapsed position to an expanded position in which both of the branch sections are substantially cylindrical; and wherein while in the collapsed position, a lower portion of each of the outer side wall portions of the upper section is deformed into a configuration having a single depression; and while in the collapsed position, an tipper portion of the outer side wall of each of the branch sections is deformed into a configuration having a single depression that extends downward from one of the depressions of the upper section, each of the depressions of the branch sections being in substantial contact with an interior surface of the inner side wall portion of each of the branch sections.
  • 10. The apparatus according to claim 9, wherein while moving from the collapsed position to the expanded position, an upper section minor axis dimension increases, the upper section minor axis dimension being measured across the lower portion of the upper section in a plane perpendicular to a line bisecting equally each of the branch sections.
  • 11. The apparatus according to claim 9, wherein while moving from the collapsed position to the expanded position, an upper section major axis dimension increases, the upper section major axis dimension being measured perpendicular to an upper section minor axis dimension across the lower portion of the upper section.
  • 12. The apparatus according to claim 11, wherein while moving from the collapsed position to the expanded position, a branch section major axis dimension increases, the branch section major axis dimension being measured across the branch sections from the outer side wall portion of one of the branch sections to the outer side wall portion of the other of the branch sections.
  • 13. The apparatus according to claim 9, further comprising a support member joined to the upper section at the junction, having a tail section that extends between the branch sections and a pair of arms, each of the arms extending upward and joining the upper section, and wherein a line equally bisecting the arms and passing through the longitudinal axis of the upper section is substantially perpendicular to a line equally bisecting each of the branch sections and passing through the longitudinal axis.
  • 14. The apparatus according to claim 13, wherein the tail section comprises a pair of ribs interconnected by a web that is located in a plane that bisects the arms, the web defining an inner separation wall between the branch sections at the junction with the upper section and having an upper portion of substantially constant thickness.
  • 15. The apparatus according to claim 13, wherein the arms move farther apart from each other when moving from the collapsed position to the expanded position.
  • 16. The apparatus according to claim 13, further comprising a stress relief notch with a radius formed at a comer of each of the arms with the tail section.
  • 17. A method for providing a junction between an upper string of casing and two lower strings of casing, comprising:(a) providing a junction apparatus that comprises an upper section and a pair of branch sections that join each other at a junction with each other and with a lower end of the upper section and extend downward from the upper section; (b) collapsing the junction apparatus into a smaller effective diameter by forming two oppositely facing single depressions in a lower portion of the upper section, and forming a single depression in an outer side wall portion of each of the branch sections; (c) connecting the upper section of the junction apparatus to the upper string of casing and running the junction apparatus into the well while collapsed; (d) while the junction apparatus is in the well, applying an internal force to the junction apparatus to cause the depressions in the lower portion of the upper section and in the branch sections to substantially disappear, and causing the branch sections to move apart from each other.
  • 18. The method according to claim 17, wherein step (d) causes a minor axis dimension across a lower portion of the upper section to increase, the minor axis dimension being measured substantially perpendicular to a line equally bisecting the branch sections.
  • 19. The method according to claim 17, wherein step (d) also causes a major axis dimension across a lower portion of the upper section to increase, the major axis dimension being measured substantially perpendicular to a minor axis dimension.
  • 20. The method according to claim 17, wherein step (d) is performed by applying internal fluid pressure to the junction apparatus.
  • 21. The method according to claim 17, wherein one of the lower strings of casing is attached to one of the branch sections prior to running the junction apparatus into the well.
  • 22. The method according to claim 21, wherein the other of the branch sections is plugged prior to running in the well, and step(d) is performed by applying internal fluid pressure to the junction apparatus.
CROSS-REFERENCE

This is a continuation-in-part application of Ser. No. 09/148,667, filed Sep. 4, 1998, now abandoned, which was a continuation-in-part of Ser. No. 08/925,971, filed Sep. 9, 1997, U.S. Pat. No. 5,979,560. This application also claims priority to provisional application Ser. No. 60/109,842, filed Nov. 25, 1998.

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Provisional Applications (1)
Number Date Country
60/109842 Nov 1998 US
Continuation in Parts (2)
Number Date Country
Parent 09/148667 Sep 1998 US
Child 09/448772 US
Parent 08/925971 Sep 1997 US
Child 09/148667 US