US20050178555A1 - Sealed multilateral junction system - Google Patents

Abstract

A sealed multilateral junction system provides fluid isolation between intersecting wellbores in a subterranean well. In a described embodiment, a method of forming a wellbore junction includes the steps of sealing a tubular string in a branch wellbore to a tubular structure in a parent wellbore. The tubular string may be secured to the tubular structure utilizing a flange which is larger in size than a window formed in the tubular structure. The flange may be sealed to the tubular structure about the window by a metal to metal seal or by adhering the flange to the tubular structure.

Description

BACKGROUND
• The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a method of forming sealed wellbore junctions.
• Many systems have been developed for connecting intersecting wellbores in a well. Unfortunately, these systems typically involve methods which unduly restrict access to one or both of the intersecting wellbores, restrict the flow of fluids, are very complex or require very sophisticated equipment to perform, are time-consuming in that they require a large number of trips into the well, do not provide secure attachment between casing in the parent wellbore and a liner in the branch wellbore and/or do not provide a high degree of sealing between the intersecting wellbores.
• For example, some wellbore junction systems rely on cement alone to provide a seal between the interior of the wellbore junction and a formation surrounding the junction. In these systems, there is no attachment between the casing in the parent wellbore and the liner in the branch wellbore, other than that provided by the cement. These systems are acceptable in some circumstances, but it would be desirable in other circumstances to be able to provide more secure attachment between the tubulars in the intersecting wellbores, and to provide more effective sealing between the tubulars.
SUMMARY
• In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method of forming a wellbore junction is provided which both securely attaches tubulars in intersecting wellbores and effectively seals between the tubulars. The method is straightforward and convenient in its performance, does not unduly restrict flow or access through the junction, and does not require an inordinate number of trips into the well.
• In one aspect of the invention, a method is provided for forming a wellbore junction which includes a step of expanding a member within a tubular structure positioned at an intersection of two wellbores. This expansion of the member may perform several functions. For example, the expanded member may secure an end of a tubular string which extends into a branch wellbore. The expanded member may also seal to the tubular string and/or to the tubular structure.
• In another aspect of the invention, the tubular string may be installed in the branch wellbore through a window formed through the tubular structure. An engagement device on the tubular string engages the tubular structure to secure the tubular string to the tubular structure. For example, the engagement device may be a flange which is larger in size than the window of the tubular structure and is prevented from passing therethrough, thereby fixing the position of the tubular string relative to the tubular structure.
• In yet another aspect of the invention, a whipstock may be used to drill the branch wellbore through the window in the tubular structure. Thereafter, the whipstock is used to install the tubular string in the branch wellbore. After installation of the tubular string, the whipstock may be retrieved from the parent wellbore, thereby permitting full bore access through the wellbore junction in the parent wellbore. The tubular string may be installed and the whipstock retrieved in only a single trip into the well using a unique tool string.
• In still another aspect of the invention, the window may be formed in the tubular structure prior to cementing the tubular structure in the parent wellbore. To prevent cement flow through the window, a retrievable sleeve is used inside the tubular structure. After cementing, the sleeve is retrieved from within the tubular structure.
• Various types of seals may be used between various elements of the wellbore junction. For example metal to metal seals may be used, or elements of the wellbore junction may be adhesively bonded to each other, etc.
• These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of a method of forming a wellbore junction which embodies principles of the present invention and wherein a tubular structure has been cemented within a parent wellbore;
• FIG. 2 is an enlarged cross-sectional view of the method wherein a branch wellbore has been drilled through the tubular structure utilizing a whipstock positioned in the tubular structure;
• FIG. 3 is a cross-sectional view of the method wherein a tubular string is being installed in the branch wellbore;
• FIG. 4 is an enlarged cross-sectional view of the method wherein a sleeve is being expanded within the tubular structure to thereby secure and seal the tubular string to the tubular structure;
• FIG. 5 is a cross-sectional view taken along line5-5 ofFIG. 4, showing the sleeve expanded within the tubular structure;
• FIGS. 6 & 7 are cross-sectional views of the sleeve in its radially compressed and expanded configurations, respectively;
• FIGS. 8-13 are cross-sectional views of a second method embodying principles of the present invention;
• FIGS. 14-17 are cross-sectional views of a third method embodying principles of the present invention;
• FIGS. 18-20 are cross-sectional views of a fourth method embodying principles of the present invention;
• FIGS. 21-25 are cross-sectional views of a fifth method embodying principles of the present invention;
• FIGS. 26 & 27 are cross-sectional views of a sixth method embodying principles of the present invention;
• FIGS. 28 & 29 are cross-sectional views of a seventh method embodying principles of the present invention;
• FIG. 30 is a cross-sectional view of an eighth method embodying principles of the present invention; and
• FIGS. 31-35 are cross-sectional views of a ninth method embodying principles of the present invention.
DETAILED DESCRIPTION
• Representatively illustrated inFIG. 1 is amethod10 which embodies principles of the present invention. In the following description of themethod10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.
• As depicted inFIG. 1, several steps of themethod10 have already been performed. Aparent wellbore12 has been drilled and atubular structure14 has been positioned in the parent wellbore. Thetubular structure14 is part of acasing string16 used to line theparent wellbore12.
• It should be understood that use of the terms “parent wellbore” and “casing string” herein are not to be taken as limiting the invention to the particular illustrated elements of themethod10. Theparent wellbore12 could be any wellbore, such as a branch of another wellbore, and does not necessarily extend directly to the earth's surface. Thecasing string16 could be any type of tubular string, such as a liner string, etc. The terms “casing string” and “liner string” are used herein to indicate tubular strings of any type, such as segmented or unsegmented tubular strings, tubular strings made of any materials, including nonmetal materials, etc. Thus, the reader will appreciate that these and other descriptive terms used herein are merely for convenience in clearly explaining the illustrated embodiments of the invention, and are not used for limiting the scope of the invention.
• Thecasing string16 also includes twoanchoring profiles18,20 for purposes that are described below. Thelower profile20 may be an orienting latch profile, for example, a profile which serves to rotationally orient a device engaged therewith relative to thewindow28. Theupper profile18 may also be an orienting latch profile. Such orienting profiles are well known to those skilled in the art.
• Atubular shield22 is received within thecasing string16, andseals24,26 carried on the shield are positioned at an upper end of thetubular structure14 and at a lower end of theanchoring profile20, respectively. Theshield22 is a relatively thin sleeve as depicted inFIG. 1, but it could have other shapes and other configurations in keeping with the principles of the invention.
• Theshield22 serves to prevent flow through awindow28 formed laterally through a sidewall of thetubular structure14. Specifically, theshield22 prevents the flow of cement through thewindow28 when thecasing string16 is cemented in theparent wellbore12. Theshield22 also prevents fouling of thelower profile20 during the cementing operation, and the shield may be releasably engaged with the profile to secure it in position during the cementing operation and to enable it to be retrieved from thecasing string16 after the cementing operation, for example; by providing an appropriate convention latch on the shield.
• Theshield22 prevents cement from flowing out to thewindow28 when cement is pumped through thecasing string16. Other means may be used external to thetubular structure14 to prevent cement from flowing in to thewindow28, for example, an outer membrane, a fiberglass wrap about the tubular structure, a substance filling the window and any space between the window and theshield22, etc.
• At this point it should be noted that the use of the terms “cement” and “cementing operation” herein are used to indicate any substance and any method of deploying that substance to fill the annular space between a tubular string and a wellbore, to seal between the tubular string and the wellbore and to secure the tubular string within the wellbore. Such substances may include, for example, various cementitious compositions, polymer compositions such as epoxies, foamed compositions, other types of materials, etc.
• At the time thecasing string16 is positioned in thewellbore12, but prior to the cementing operation, thetubular structure14 is rotationally oriented so that thewindow28 faces in a direction of a desired branch wellbore to extend outwardly from the window. Thus, thetubular structure14 is positioned at the future intersection between the parent wellbore12 and the branch wellbore-to-be-drilled, with thewindow28 facing in the direction of the future branch wellbore. The rotational orientation may be accomplished in any of a variety of ways, for example, by engaging a gyroscopic device with theupper profile18, by engaging a low side indicator with theshield22, etc. Such rotational orienting devices (gyroscope, low side indicator, etc.) are well known to those skilled in the art.
• After thetubular structure14 is positioned in thewellbore12 with thewindow28 facing in the proper direction, thecasing string16 is cemented in place in the wellbore. When the cementing operation is concluded, theshield22 is retrieved from thecasing string16.
• Referring additionally now toFIG. 2, an enlarged view of themethod10 is representatively illustrated wherein theshield22 has been retrieved. Awhipstock30 or other type of deflection device has been installed in thetubular structure14 by engaging keys, lugs ordogs32 with theprofile20, thereby releasably securing the whipstock in position and rotationally aligning anupper deflection surface34 with thewindow28.
• Thewhipstock30 also includes aninner passage36 and aprofile38 formed internally on the passage for retrieving the whipstock. Of course, other means for retrieving thewhipstock30 could be used, for example, a washover tool, a spear, an overshot, etc.
• As depicted inFIG. 2, one or more cutting devices, such as drill bits, etc., have been deflected off of thedeflection surface34 and through thewindow28 to drill abranch wellbore40 extending outwardly from the window. As discussed above, the term “branch wellbore” should not be taken as limiting the invention, since thewellbore40 could be a parent of another wellbore, or could be another type of wellbore, etc.
• Referring additionally now toFIG. 3, themethod10 is representatively illustrated wherein atubular string42 has been installed in thebranch wellbore40. Thetubular string42 may be made up substantially of liner or any other type of tubular material.
• As depicted inFIG. 3, thetubular string42 includes anengagement device44 for engaging thetubular structure14 and securing an upper end of the tubular string thereto. Thetubular string42 also includes a flex or swivel joint46 for enabling, or at least enhancing, deflection of the tubular string from the parent wellbore12 into thebranch wellbore40. Alternatively, or in addition, the swivel joint46 permits rotation of an upper portion of thetubular string42 relative to a lower portion of the tubular string in the rotational alignment step of themethod10 described below. Thetubular string42 is deflected off of thedeflection surface34 as it is conveyed downwardly attached to atool string48.
• Thetool string48 includes ananchor50 for releasable engagement with theupper profile18, a runningtool52 for releasable attachment to thetubular string42, and aretrieval tool54 for retrieving thewhipstock30. The runningtool52 may include keys, lugs or dogs for engaging an internal profile (not shown) of thetubular string42. Theretrieval tool54 may include keys, lugs or dogs for engagement with theprofile38 of thewhipstock30.
• When theanchor50 is engaged with theprofile18, thetubular string42 is rotationally aligned so that theengagement device44 will properly engage thetubular structure14 as further described below. In addition, theanchor50 is preferably spaced apart from theengagement device44 so that when the anchor is engaged with theprofile18 and ashoulder56 formed on atubing string58 of thetool string48 contacts the anchor, the engagement device is properly positioned in engagement with thetubular structure14.
• Specifically, thetubing string58 is slidably received within theanchor50. When theshoulder56 contacts theanchor50, theengagement device44 is a predetermined distance from the anchor. This distance between theanchor50 and theengagement device44 corresponds with another predetermined distance between theprofile18 and thetubular structure14. Thus, when thetubular string42 is being conveyed into the branch wellbore40, theengagement device44 will properly engage thetubular structure14 as theshoulder56 contacts theanchor50.
• The runningtool52 may then be released from thetubular string42, thetool string48 may be raised into the parent wellbore12, and then theretrieval tool54 may be engaged with theprofile38 in thewhipstock30 to retrieve the whipstock from the parent wellbore. Note that the installation of thetubular string42 and the retrieval of thewhipstock30 may thus be accomplished in a single trip into the well.
• Theengagement device44 is depicted inFIG. 3 as a flange which extends outwardly from the upper end of thetubular string42. Theengagement device44 includes a backing plate or landingplate60 which is received in anopening62 formed through a sidewall of aguide structure64 of thetubular structure14. Preferably, theopening62 is complementarily shaped relative to theplate60, and this complementary engagement maintains the alignment between thetubular string42 and thetubular structure14. For example, engagement between theplate60 and theopening62 supports the upper end of thetubular string42, so that an annular space exists about the upper end of the tubular string for later placement of cement therein.
• Theguide structure64 is more clearly visible in the enlarged view ofFIG. 2. In this view it may also be seen that theopening62 includes anelongated slot66 at a lower end thereof. Preferably, theplate60 includes a downwardly extending tab68 (seeFIG. 3) which engages theslot66 and thereby prevents rotation of theengagement device44 relative to thewindow28.
• Theengagement device44 is larger in size than thewindow28, and so the engagement device prevents thetubular string42 from being conveyed too far into thebranch wellbore40. Theengagement device44 thus secures the upper end of thetubular string42 relative to thetubular structure14. Of course, other types of engagement devices may be used in place of the illustrated flange and backing plate, for example, an orienting profile could be formed on the tubular structure and keys, dogs or lugs could be carried on thetubular string42 for engagement therewith to orient and secure the tubular string relative to the tubular structure.
• As depicted inFIG. 3, theengagement device44 carries a seal70 thereon which circumscribes theopening62 and sealingly engages theguide structure64. Theguide structure64 carries seals72,74 thereon which sealingly engage above and below thewindow28. Thus, thetubular string42 is sealed to thetubular structure14 so that leakage therebetween is prevented. Theseals70,72,74, or any of them, may be elastomer seals, non-elastomer seals, metal to metal seals, expanding seals, and/or seals created by adhesive bonding, such as by using epoxy or another adhesive.
• Referring additionally now toFIG. 4, an enlarged view is representatively illustrated of themethod10 after thetubular string42 is installed in the branch wellbore40 and thewhipstock30 is retrieved from the well. Note that an alternatively constructedengagement device44 is illustrated inFIG. 4 which does not include theplate60. Instead, the flange portion of theengagement device44 is received in theopening62 and the engagement device is sealed to thetubular structure14 about thewindow28 using one ormore seals76,78,80 circumscribing the window. Theseal76 is an adhesive, theseal78 is an o-ring and theseal80 is a metal to metal seal.
• To further secure thetubular string42 to thetubular structure14, amember82 is expanded within the tubular structure using anexpansion device84. As depicted inFIG. 4, themember82 is a tubular sleeve having anopening86 formed through a sidewall thereof. Of course, other expandable member shapes and configurations could be used in keeping with the principles of the invention.
• Theopening86 is rotationally aligned with aninternal flow passage88 of thetubular string42, for example, by engaging theexpansion device84 with theupper profile18. Then, theexpansion device84 is actuated to displace a wedge or cone go upwardly through themember82, thereby expanding the member outwardly. Such outward expansion also outwardly displaces seals92,94,96,98,100 carried on the member.
• Theseals94,96 sealingly engage theguide structure64 above and below theopening62. Theseals92,98 are metal to metal seals and sealingly engage thetubular structure14 above and below theguide structure64. Theseal100 is an adhesive seal which circumscribes thepassage88 and sealingly engages the flange portion of theengagement device44. Of course, theseals92,94,96,98,100, or any of them, may be any type of seal, for example, elastomer, non-elastomer, metal to metal, adhesive, etc.
• After themember82 is expanded, theexpansion device84 is retrieved from the well and thetubular string42 is cemented within thebranch wellbore40. For example, a foamed composition may be injected into the annulus radially between thetubular string42 and thebranch wellbore40. The foamed composition could expand in the annulus to fill any voids therein, and could expand to fill any voids about thestructure14 in thewellbore12.
• Note that theengagement device44 is retained between themember82 and thetubular structure14, thereby preventing upward and downward displacement of thetubular string42. In addition, where metal to metal seals are used, the expansion of themember82 maintains a biasing force on these seals to maintain sealing engagement.
• Referring additionally now toFIG. 5, a partial cross-sectional view, taken along line5-5 ofFIG. 4 is representatively illustrated. In this view, only thetubular string42,tubular structure14,guide structure64 andexpandable member82 cross-sections are shown for clarity of illustration. FromFIG. 5, it may be more clearly appreciated how theengagement device44 is received in theguide structure64, and how expansion of themember82 secures the engagement device in thetubular structure14.
• In addition, note that no separate seals are visible inFIG. 5 for sealing between theengagement device44 and thetubular structure14 orexpansion member82. This is due to the fact thatFIG. 5 illustrates an alternate sealing method wherein sealing between theengagement device44 and each of thetubular structure14 andexpansion member82 is accomplished by metal to metal contact between these elements.
• Specifically, expansion of themember82 causes it to press against an interior surface theengagement device44 circumscribing thepassage88, which in turn causes an exterior surface of the engagement device to press against an interior surface of thetubular structure14 circumscribing thewindow28. This pressing of one element surface against another when themember82 is expanded results in metal to metal seals being formed between the surfaces. However, as mentioned above, any type of seal may be used in keeping with the principles of the invention.
• Referring additionally now toFIGS. 6 and 7, theexpansion member82 is representatively illustrated in its radially compressed and radially expanded configurations, respectively. InFIG. 6, it may be seen that theexpansion member82 in its radially compressed configuration has a circumferentially corrugated shape, that is, the member has a convoluted shape about its circumference. InFIG. 7, themember82 is radially expanded so that it attains a substantially cylindrical tubular shape, that is, it has a substantially circular cross-sectional shape.
• Referring additionally now toFIGS. 8-13, anothermethod110 embodying principles of the invention is representatively illustrated. In themethod110, atubular structure112 is interconnected in acasing string114 and conveyed into aparent wellbore116. Thetubular structure112 preferably includes a tubularouter shield118 outwardly overlying awindow120 formed through a sidewall of the tubular structure. Theshield118 is preferably made of a relatively easily drilled or milled material, such as aluminum.
• Theshield118 prevents cement from flowing outwardly through thewindow120 when thecasing string114 is cemented in thewellbore116. Theshield118 also transmits torque through thetubular structure112 from above to below thewindow120, due to the fact that the shield is rotationally secured to the tubular structure above and below the window, for example, by castellated engagement between upper and lower ends of the shield and the tubular structure above and below the window, respectively.
• Thetubular structure112 is rotationally aligned with a branch wellbore-to-be-drilled122, so that thewindow120 faces in the radial direction of the desired branch wellbore. This rotational alignment may be accomplished, for example, by use of a conventional wireline-conveyed direction sensing tool (not shown) engaged with a key orkeyway124 having a known orientation relative to thewindow120. Other rotational alignment means may be used in keeping with the principles of the invention.
• InFIG. 9 it may be seen that awork string126 is used to convey a mill, drill orother cutting tool128, a whipstock orother deflection device130 and an orienting latch oranchor132 into thecasing string114. Thedrill128 is releasably attached to thewhipstock130, for example, by ashear bolt134, thereby enabling the drill and whipstock to be conveyed into thecasing string114 in a single trip into the well.
• Theanchor132 is engaged with an anchoring and orientingprofile136 in thecasing string114 below thetubular structure112. Such engagement secures thewhipstock130 relative to thetubular structure112 and rotationally orients the whipstock relative to the tubular structure, so that an upperinclined deflection surface138 of the whipstock faces toward thewindow120 and the desiredbranch wellbore122.
• Thereafter, theshear bolt134 is sheared (for example, by slacking off on thework string126, thereby applying a downwardly directed force to the bolt), permitting thedrill128 to be laterally deflected off of thesurface138 and through thewindow120. Thedrill128 is used to drill or mill outwardly through theshield118, and to drill thebranch wellbore122. Of course, multiple cutting tools and different types of cutting tools may be used for thedrill128 during this drilling process.
• As depicted inFIG. 9, thecasing string114 has been cemented within thewellbore116 prior to the drilling process. However, it is to be clearly understood that it is not necessary for thetubular structure112 to be cemented in thewellbore116 at this time. It may be desirable to delay cementing of thecasing string114, or to forego cementing of thetubular structure112, as set forth in further detail below.
• InFIG. 10 it may be seen that the branch wellbore122 has been drilled extending outwardly from thewindow120 of thetubular structure112 by laterally deflecting one or more cutting tools from the parent wellbore116 off of thedeflection surface138 of thewhipstock130.
• InFIG. 11 it may be seen that aliner string140 is conveyed through thecasing string114, and a lower end of the liner string is laterally deflected off of thesurface138, through thewindow120, and into thebranch wellbore122. Anengagement device142 attached at an upper end of theliner string140 engages atubular guide structure144 of thetubular structure112, thereby securing the upper end of the liner string to the tubular structure. This engagement between thedevice142 and thestructure112 forms a load-bearing connection between thecasing string114 and theliner string140, so that further displacement of the liner string into the branch wellbore122 is prevented.
• Engagement between thedevice142 and thestructure144 may also rotationally secure the device relative to thetubular structure112. For example, theslot66 andtab68 described above may be used on thedevice142 andstructure144, respectively, to prevent rotation of the device in thetubular structure112. Other types of complementary engagement, and other means of rotationally securing thedevice142 relative to thetubular structure112 may be used in keeping with the principles of the invention.
• Note that thedevice142 is depicted inFIG. 11 as a radially outwardly extending flange-shaped member which inwardly overlaps the perimeter of thewindow120. Thedevice142 inwardly circumscribes thewindow120 and overlaps its perimeter, so if one or both mating surfaces of the device andtubular structure112 are provided with a suitable layer of sealing material (such as an elastomer, adhesive, relatively soft metal, etc.), aseal146 may be formed between the device and the tubular structure due to the contact therebetween. Thedevice142 may be otherwise shaped, and may be otherwise sealed to thetubular structure112 in keeping with the principles of the invention.
• InFIG. 12 it may be seen that thewhipstock130 andanchor132 are retrieved from the well and a generally tubularexpandable member148 is conveyed into thetubular structure112 and expanded therein. For example, theexpandable member148 may be expanded radially outward using theexpansion device84, from a radially compressed configuration (such as that depicted inFIG. 6) to a radially extended configuration (such as that depicted inFIG. 7).
• Themember148 preferably has anopening150 formed through a sidewall thereof when it is conveyed into thestructure112. In that case, theopening150 is preferably rotationally aligned with the window120 (and thus rotationally aligned with aninternal flow passage152 of the liner string140) prior to themember148 being radially expanded. Alternatively, themember148 could be conveyed into thestructure112 without theopening150 having previously been formed, then expanded, and then a whipstock or other deflection device could be used to direct a cutting tool to form the opening through the sidewall of the member.
• Note that themethod110 is illustrated inFIG. 12 as though thecasing string114 is cemented in thewellbore116 at the time themember148 is expanded in thestructure112. However, thestructure112 could be cemented in thewellbore116 after themember148 is expanded therein.
• After being expanded radially outward, themember148 preferably has an internal diameter D1 which is substantially equal to, or at least as great as, an internal diameter D2 of thecasing string114 above thestructure112. Thus, themember148 does not obstruct flow or access through thestructure112.
• Note that a separate seal is not depicted inFIG. 12 between themember148 and thedevice142 or thestructure112. Instead, seals154,156 between themember148 and thestructure112 above and below theguide structure144 are formed by contact between themember148 and thestructure112 when the member is expanded radially outward. For example, one or both mating surfaces of themember148 andtubular structure112 may be provided with a suitable layer of sealing material (such as an elastomer, adhesive, relatively soft metal, etc.), so that theseals154,156 are formed between the member and the tubular structure due to the contact therebetween. Themember148 may be otherwise sealed to thetubular structure112 in keeping with the principles of the invention.
• To enhance sealing contact between themember148 and thestructure112 and/or to ensure sufficient forming of the internal diameter D1, the structure may be expanded radially outward somewhat at the time the member is expanded radially outward, for example, by theexpansion device84. This technique may produce some outward elastic deformation in thestructure112, so that after the expansion process the structure will be biased radially inward to increase the surface contact pressure between the structure and themember148. Such an expansion technique may be particularly useful where it is desired for theseals154,156 to be metal to metal seals. If this expansion technique is used, it may be desirable to delay cementing thestructure112 in thewellbore116 until after the expansion process is completed.
• Similarly, aseal158 between themember148 and thedevice142 outwardly circumscribing theopening150 is formed by contact between themember148 and the device when the member is expanded radially outward. For example, one or both mating surfaces of themember148 anddevice142 may be provided with a suitable layer of sealing material (such as an elastomer, adhesive, relatively soft metal, etc.), so that theseal158 is formed between the member and the device due to the contact therebetween. Themember148 may be otherwise sealed to thedevice142 in keeping with the principles of the invention. Radially outward deformation of thestructure112 at the time themember148 is expanded radially outward (as described above) may also enhance sealing contact between the member and thedevice142, particularly where theseal158 is a metal to metal seal.
• Theexpandable member148 secures thedevice142 in its engagement with theguide structure144. It will be readily appreciated that inward displacement of thedevice142 is not permitted after themember148 has been expanded. Furthermore, in the event that thedevice142 has not yet fully engaged theguide structure144 at the time themember148 is expanded (for example, the device could be somewhat inwardly disposed relative to the guide structure), expansion of the member will ensure that the device is fully engaged with the guide structure (for example, by outwardly displacing the device somewhat).
• Referring additionally now toFIG. 13, an alternate procedure for use in themethod110 is representatively illustrated. This alternate procedure may be compared to the illustration provided inFIG. 8. Instead of theouter shield118, the procedure illustrated inFIG. 13 uses an inner generallytubular shield160 having an inclined upper surface ormuleshoe162. Although no separate seals are shown inFIG. 13, theinner shield160 is preferably sealed to thetubular structure112 above and below theguide structure144, so that cement or debris in thecasing string114 is not permitted to flow into thewindow120 from the interior of thestructure112. Preferably, theinner shield160 is made of metal and is retrievable from within thestructure112 after the cementing process.
• To prevent cement or debris from flowing into thestructure112 through thewindow120, a generally tubularouter shield164 outwardly overlies the window. Preferably, theouter shield164 is made of a relatively easily drillable material, such as a composite material (e.g., fiberglass, etc.). A fluid166 having a relatively high viscosity is contained between the inner andouter shields162,164 to provide support for the outer shield against external pressure, and to aid in preventing leakage of external fluids into the area between the shields. A suitable fluid for use as the fluid166 is known by the trade name Glcogel.
• Themuleshoe162 provides a convenient surface for engagement by a conventional wireline-conveyed orienting tool (not shown). Such a tool may be engaged with themuleshoe162 and used to rotationally orient thestructure112 relative to the branch wellbore-to-be-drilled122, since the muleshoe has a known radial orientation relative to thewindow120.
• After thestructure112 has been appropriately rotationally oriented, thecasing string114 may be cemented in thewellbore116, and theinner shield160 may then be retrieved from the well. After retrieval of theinner shield160, themethod110 may proceed as described above, i.e., thewhipstock130 andanchor132 may be installed, etc. Alternatively, theinner shield160 may be retrieved prior to cementing thestructure112 in thewellbore116.
• Referring additionally now toFIGS. 14-17, anothermethod170 embodying principles of the invention is representatively illustrated. Themethod170 differs from the other methods described above in substantial part in that a specially constructed tubular structure is not necessarily used in acasing string172 to provide a window through a sidewall of the string. Instead, awindow176 is formed through a sidewall of thecasing string172 using conventional means, such as by use of a conventional whipstock (not shown) anchored and oriented in the casing string according to conventional practice.
• One of the many benefits of themethod170 is that it may be used in existing wells wherein casing has already been installed. Furthermore, themethod170 may even be performed in wells in which thewindow176 has already been formed in thecasing string172. However, it is to be clearly understood that it is not necessary for themethod170 to be performed in a well wherein existing casing has already been cemented in place. Themethod170 may be performed in newly drilled or previously uncased wells, and in wells in which the casing has not yet been cemented in place.
• InFIG. 15 it may be seen that aliner string178 is conveyed into abranch wellbore180 which has been drilled extending outwardly from thewindow176. At its upper end, theliner string178 includes anengagement device182 which engages the interior of thecasing string172 and prevents further displacement of theliner string178 into thebranch wellbore180. Engagement of thedevice182 with thecasing string172 may also rotationally align the device with respect to the casing string.
• As depicted inFIG. 15, thedevice182 is a flange extending outwardly from the remainder of theliner string178. Thedevice182 inwardly overlies the perimeter of thewindow176 and circumscribes the window. Contact between an outer surface of thedevice182 and an inner surface of thecasing string172 may be used to provide aseal184 therebetween, for example, if one or both of the inner and outer surfaces is provided with a layer of a suitable sealing material, such as an elastomer, adhesive or a relatively soft metal, etc. Thus, theseal184 may be a metal to metal seal. Other types of seals may be used in keeping with the principles of the invention.
• In an optional procedure of themethod170, the liner string178 (or at least the device182) may be in a radially compressed configuration (such as that depicted inFIG. 6) when it is initially installed in the branch wellbore180, and then extended to a radially expanded configuration (such as that depicted inFIG. 7) thereafter. This expansion of theliner string178, or at least expansion of thedevice182, may be used to bring the device into sealing contact with thecasing string172.
• InFIG. 16 it may be seen that a generally tubularexpandable member186 is conveyed into thecasing string172 and aligned longitudinally with thedevice182. Themember186 has anopening188 formed through a sidewall thereof. Theopening188 is rotationally aligned with the window176 (and thus aligned with aflow passage190 of the liner string178).
• However, it is not necessary for theopening188 to be formed in themember186 prior to conveying the member into the well, or for the opening to be aligned with thewindow176 at the time it is positioned opposite thedevice182. For example, theopening188 could be formed after themember186 is installed in thecasing string172, such as by using a whipstock or other deflection device to direct a cutting tool to cut the opening laterally through the sidewall of the member.
• As depicted inFIG. 16, themember186 has an outer layer of asuitable sealing material192 thereon. The sealingmaterial192 may be any type of material which may be used to form a seal between surfaces brought into contact with each other. For example, the sealingmaterial192 may be an elastomer, adhesive or relatively soft metal, etc. Other types of seals may be used in keeping with the principles of the invention.
• InFIG. 17 it may be seen that themember186 is expanded radially outward, so that it now contacts the interior of thecasing string172 and thedevice182. Preferably, such contact results in sealing engagement between themember186 and the interior surface of thecasing string172, and between the member and thedevice182.
• Specifically, the sealingmaterial192 seals between themember186 and thecasing string172 above, below and circumscribing thedevice182. The sealingmaterial192 also seals between themember186 and thedevice182 around the outer periphery of theopening188, that is, sealing engagement between thedevice182 and themember186 circumscribes theopening188. Thus, the interiors of the casing andliner strings172,178 are completely isolated from thewellbores174,180 external to the strings. This substantial benefit of themethod170 is also provided by the other methods described herein.
• As depicted inFIG. 17, thecasing string172 is outwardly deformed when themember186 is radially outwardly expanded therein. At least some elastic deformation, and possibly some plastic deformation, of thecasing string172 outwardly overlying themember186 is experienced, thereby recessing the member into the interior wall of the casing string.
• As a result, the inner diameter D3 of themember186 is substantially equal to, or at least as great as, the inner diameter D4 of thecasing string172 above thewindow176. Preferably, during the expansion process, the inner diameter D3 of themember186 is enlarged until it is greater than the inner diameter D4 of thecasing string172, so that after the expansion force is removed, the diameter D3 will relax to a dimension no less than the diameter D4.
• Thus, themethod170 does not result in substantial restriction of flow or access through thecasing string172. This substantial benefit of themethod170 is also provided by other methods described herein.
• Outward elastic deformation of thecasing string172 in the portions thereof overlying themember186 is desirable in that it inwardly biases the casing string, increasing the contact pressure between the mating surfaces of the member and the casing string, thereby enhancing the seal therebetween, after the member has been expanded. However, it is to be clearly understood that it is not necessary, in keeping with the principles of the invention, for thecasing string172 to be outwardly deformed, since themember186 may be expanded radially outward into sealing contact with the interior surface of the casing string without deforming the casing string at all.
• When themember186 is expanded, it also outwardly displaces thedevice182. This outward displacement of thedevice182 further outwardly deforms thecasing string172 where it overlies the device. Elastic deformation of thecasing string172 overlying thedevice182 is desirable in that it results in inward biasing of the casing string when the expansion force is removed. This enhances theseal184 between thedevice182 and thecasing string172, and further increases the contact pressure on the sealing material between thedevice182 and themember186.
• Themethod170 is depicted inFIG. 17 as though thecasing string172 is not yet cemented in the parent wellbore174 at the time themember186 is expanded therein. This alternate order of steps in themethod170 may be desirable in that it may facilitate outward deformation of thecasing string172 above and below thewindow176. The casing and/orliner strings172,178 may be cemented in therespective wellbores174,180 after themember186 is expanded.
• Referring additionally now toFIGS. 18-20, anothermethod200 embodying principles of the invention is representatively illustrated. InFIG. 18 it may be seen that atubular structure202 is cemented in aparent wellbore204 at an intersection with abranch wellbore206. However, it is not necessary for thetubular structure202 to be cemented in thewellbore204 until later in themethod200, if at all.
• Thestructure202 is interconnected in acasing string208. Thecasing string208 is rotationally oriented in thewellbore204 so that awindow210 formed through a sidewall of thestructure202 is aligned with thebranch wellbore206. Note that the window may be formed through the sidewall of thestructure202, and that the branch wellbore206 may be drilled, either before or after the structure is conveyed into thewellbore204.
• Aliner string212 is conveyed into the branch wellbore206 in a radially compressed configuration. Even though it is radially compressed, a flange-shapedengagement device214 at an upper end of theliner string212 is larger than thewindow210, and so the device prevents further displacement of the liner string into thewellbore206. Preferably, this engagement between thedevice214 and thestructure202 is sufficiently load-bearing so that it may support theliner string212 in thewellbore206.
• Anannular space216 is provided radially between thedevice214 and anopening218 formed through the sidewall of aguide structure220. When theliner string212 is expanded, thedevice214 deforms radially outwardly into theannular space216. Theliner string212 is shown in its expanded configuration inFIG. 19.
• As depicted inFIG. 20, a generally tubularexpandable member222 is radially outwardly expanded within thestructure202. Anopening224 formed through a sidewall of themember222 is rotationally aligned with a flow passage of theliner string212. Theopening224 may be formed before or after themember222 is expanded.
• Preferably, this expansion of themember222 seals between the outer surface of the member and the inner surface of thestructure202 above and below theguide structure220, and seals between the member and thedevice214. Thus, the interiors of the casing andliner strings208,212 are isolated from thewellbores204,206 external to the strings. Alternatively, or in addition, a seal may be formed between thedevice214 and thestructure202 circumscribing thewindow210 where the structure outwardly overlies the device.
• Preferably the seals obtained by expansion of themember222 are due to surface contact between elements, at least one of which is displaced in the expansion process. For example, one of both of themember222 andstructure202 may have a layer of sealing material (e.g., a layer of elastomer, adhesive, or soft metal, etc.) thereon which is brought into contact with the other element when the member is expanded. Metal to metal seals are preferred, although other types of seals may be used in keeping with the principles of the invention.
• As depicted inFIG. 20, thetubular structure202, and thecasing string208 somewhat above and below the structure, are radially outwardly expanded when themember222 is expanded. This optional step in themethod200 may be desirable to enhance access and/or flow through thestructure202, enhance sealing contact between any of themember222,device214,structure202, etc. If thecasing string208 is outwardly deformed in themethod200, it may be desirable to cement the casing string in thewellbore204 after the expansion process is completed.
• Referring additionally now toFIGS. 21-25 anothermethod230 embodying principles of the invention is representatively illustrated. As depicted inFIG. 21, anexpandable liner string232 is conveyed through acasing string234 positioned in aparent wellbore236. A lower end of theliner string232 is deflected laterally through awindow237 formed through a sidewall of atubular structure238 interconnected in thecasing string234, and into abranch wellbore240 extending outwardly from the window.
• Anexpandable liner hanger242 is connected at an upper end of theliner string232. Theliner hanger242 is positioned within thecasing string234 above thewindow237.
• Theliner string232 is then expanded radially outward as depicted inFIG. 22. As a result of this expansion process, theliner hanger242 sealingly engages between theliner string232 and thecasing string234, and anchors the liner string relative to the casing string. Another result of the expansion process is that a seal is formed between the liner string and thewindow237 of thestructure238. Thus, the interiors of the casing andliner strings232,234 are isolated from thewellbores236,240 external to the strings. The seal formed between theliner string232 and thewindow237 is preferably a metal to metal seal, although other types of seals may be used in keeping with the principles of the invention.
• Aportion244 of theliner string232 extends laterally across the interior of thecasing string234 above adeflection device246 positioned below thewindow237. As depicted inFIG. 23, a milling ordrilling guide248 is used to guide a drill, mill orother cutting tool250 to cut through the sidewall of theliner string232 at theportion244 above thedeflection device246. In this manner, access and flow between thecasing string234 above and below theliner portion244 through aninternal flow passage252 of thedeflection device246 is provided.
• Alternatively, theliner portion244 may have anopening254 formed therethrough. Theopening254 may be formed, for example, by waterjet cutting through the sidewall of theliner string232. Theopening254 may be formed before or after theliner string232 is conveyed into the well.
• Preferably, theopening254 is formed with a configuration such that it has multiple flaps orinward projections256 which may be folded to increase the inner dimension of the opening, e.g., to enlarge the opening for enhanced access and flow therethrough. As depicted inFIG. 25, theprojections256 are folded over by use of a drift or punch258, thereby enlarging theopening254 through theliner portion244.
• Theprojections256 are thus displaced into thepassage252 of thedeflection device246 below theliner string232. A seal may be formed between theliner portion244 and thedeflection device246 circumscribing theopening254 in this process of deforming theprojections256 downward into thepassage252. Preferably, the seal is due to metal to metal contact between theliner portion244 and thedeflection device246, but other types of seals may be used in keeping with the principles of the invention.
• Referring additionally now toFIGS. 26 & 27, anothermethod260 of sealing and securing aliner string262 in a branch wellbore to atubular structure264 interconnected in a casing string in a parent wellbore is representatively illustrated. Only thestructure264 andliner string262 are shown inFIG. 26 for illustrative clarity.
• InFIG. 26 it may be seen that theliner string262 is positioned so that it extends outwardly through awindow266 formed through a sidewall of thestructure264. Theliner string262 would, for example, extend into a branch wellbore intersecting the parent wellbore in which thestructure264 is positioned.
• Anupper end268 of theliner string262 remains within thetubular structure264. To secure theliner string262 in this position, a packer or other anchoring device interconnected in the liner string may be set in the branch wellbore, or a lower end of the liner string may rest against a lower end of the branch wellbore, etc. Any method of securing theliner string262 in this position may be used in keeping with the principles of the invention.
• As depicted inFIG. 26, theupper end268 is formed so that it is parallel with a longitudinal axis of thestructure264. Theupper end268 may be formed in this manner prior to conveying theliner string262 into the well, or the upper end may be formed after the liner string is positioned as shown inFIG. 26, for example, by milling an upper portion of the liner string after it is secured in position. If theupper end268 is formed prior to conveying theliner string262 into the well, then the upper end may be rotationally oriented relative to thestructure264 prior to securing theliner string262 in the position shown inFIG. 26.
• InFIG. 27 it may be seen that theupper end268 of theliner string262 is deformed radially outward so that it is received in anopening270 formed through the sidewall of a generallytubular guide structure272 in thetubular structure264. Theopening270 is rotationally aligned with thewindow266.
• Theupper end268 is deformed outward by means of amandrel274 which is conveyed into thestructure264 and deflected laterally toward the upper end of theliner string262 by adeflection device276. Themandrel274 shapes theupper end268 so that it becomes an outwardly extending flange which overlaps the interior of thestructure264 circumscribing thewindow266, that is, the flange-shapedupper end268 inwardly overlies the perimeter of the window.
• Preferably, a seal is formed between the flange-shapedupper end268 and the interior surface of thestructure264 circumscribing thewindow266. This seal may be a metal to metal seal, may be formed by a layer of sealing material on one or both of theupper end268 and thestructure264, etc. Any type of seal may be used in keeping with the principles of the invention.
• The flange-shapedupper end268 also secures theliner string262 to thestructure264 in that it prevents further outward displacement of the liner string through thewindow266. After the deforming process is completed, themandrel274 anddeflection device276 may be retrieved from within thestructure264 and a generally tubular expandable member (not shown) may be positioned in the structure and expanded therein. For example, any of theexpandable members82,148,186,222 described above may be used.
• After expansion of the member in thestructure264, the member further secures theliner string262 relative to the structure by preventing inward displacement of the liner string through thewindow266. Various seals may also be formed between the expanded member and thestructure264, the flange-shapedupper end268, and/or theguide structure272, etc. as described above. Any types of seals may be used in keeping with the principles of the invention.
• Referring additionally now toFIGS. 28 & 29, anothermethod280 of sealing and securing aliner string282 in a branch wellbore to atubular structure284 interconnected in a casing string in a parent wellbore is representatively illustrated. InFIG. 28 a generally tubularexpandable member286 used in themethod280 is shown. Themember286 has a specially configuredopening288 formed through a sidewall thereof. Theopening288 may be formed, for example, by waterjet cutting, either before or after it is conveyed into the well.
• The configuration of theopening288 provides multiple inwardly extending flaps orprojections290 which may be folded to enlarge the opening. As depicted inFIG. 29, theopening288 has been enlarged by folding theprojections290 outward into the interior of the upper end of theliner string282. Theprojections290 are deformed outward, for example, by a mandrel and deflection device such as themandrel274 anddeflection device276 described above, but any means of deforming the projections into theliner string282 may be used in keeping with the principles of the invention.
• Theprojections290 are deformed outward after themember286 is positioned within thestructure284, theopening288 is rotationally aligned with awindow292 formed through a sidewall of the structure, and the member is expanded radially outward. Of course, if theopening288 is formed after themember286 is expanded in thestructure284, then the rotational alignment step occurs when the opening is formed.
• Expansion of themember286 secures an upper flange-shapedengagement device294 relative to thestructure284. Seals may be formed between themember286,structure284,engagement device294 and/or aguide structure296, etc. as described above. Any types of seals may be used in keeping with the principles of the invention.
• Furthermore, deformation of theprojections290 into theliner string282 may also form a seal between themember286 and the liner string about theopening288. For example, a metal to metal seal may be formed by contact between an exterior surface of themember286 and an interior surface of theliner string282 when theprojections290 are deformed into the liner string. Other types of seals may be used in keeping with the principles of the invention.
• Preferably, theprojections290 are deformed into an enlarged inner diameter D5 of theliner string282. This prevents theprojections290 from unduly obstructing flow and access through aninner passage298 of theliner string282.
• Referring additionally now toFIG. 30, anothermethod300 of sealing and securing aliner string302 in a branch wellbore to atubular structure304 interconnected in a casing string in a parent wellbore is representatively illustrated. Themethod300 is similar to themethod280 in that it uses an expandable tubular member, such as themember286 having a specially configuredopening288 formed through its sidewall. However, in themethod300, themember286 is positioned and expanded radially outward within thestructure304 prior to installing theliner string302 in the branch wellbore through awindow306 formed through a sidewall of the structure.
• Expansion of themember286 within thestructure304 preferably forms a seal between the outer surface of the member and the inner surface of the structure, at least circumscribing thewindow306, and above and below the window. The seal is preferably a metal to metal seal, but other types of seals may be used in keeping with the principles of the invention.
• After themember286 has been expanded within thestructure304, theprojections290 are deformed outward through thewindow306. This outward deformation of theprojections290 may result in a seal being formed between the inner surface of thewindow306 and the outer surface of themember286 circumscribing theopening288. Preferably the seal is a metal to metal seal, but any type of seal may be used in keeping with the principles of the invention.
• After theprojections290 are deformed outward through thewindow306, theliner string302 is conveyed into the well and its lower end is deflected through thewindow306 and theopening288, and into the branch wellbore. The vast majority of theliner string302 has an outer diameter D6 which is less than an inner diameter D7 through theopening288 and, therefore, passes through the opening with some clearance therebetween. However, anupper portion308 of theliner string302 has an outer diameter D8 which is preferably at least as great as the inner diameter D7 of theopening288. If the diameter D8 is greater than the diameter D7, some additional downward force may be needed to push theupper portion308 of theliner string302 through theopening288. In this case, the linerupper portion308 may further outwardly deform theprojections290, thereby enlarging theopening288, as it is pushed through the opening.
• Contact between the outer surface of the linerupper portion308 and the inner surface of theopening288 may cause a seal to be formed therebetween circumscribing the opening. Preferably, the seal is a metal to metal seal, but other seals may be used in keeping with the principles of the invention. Anupper end310 of theliner string302 may be cut off as shown inFIG. 30, so that it does not obstruct flow or access through thestructure304. Alternatively, theupper end310 may be formed prior to conveying theliner string302 into the well.
• Referring additionally now toFIGS. 31-35, anothermethod320 embodying principles of the invention is representatively illustrated. InFIG. 31 it may be seen that aliner string322 is conveyed through acasing string324 in aparent wellbore326, and a lower end of the liner string is deflected laterally through awindow330 formed through a sidewall of the casing string, and into abranch wellbore328. Thecasing string324 may or may not be cemented in the parent wellbore326 at the time theliner string322 is installed in themethod320.
• Theliner string322 includes aportion332 which has anopening334 formed through a sidewall thereof. In addition, an external layer of sealingmaterial336 is disposed on theliner portion332. The sealingmaterial336 may be, for example, an elastomer, an adhesive, a relatively soft metal, or any other type of sealing material. Preferably, the sealingmaterial336 outwardly circumscribes theopening334 and extends circumferentially about theliner portion332 above and below the opening.
• Theliner string322 is positioned as depicted inFIG. 31, with theliner portion332 extending laterally across the interior of thecasing string324 and theopening334 facing downward. However, it is to be clearly understood that it is not necessary for theopening334 to exist in theliner portion332 prior to theliner string322 being conveyed into the well. Instead, theopening334 could be formed downhole, for example, by using a cutting tool and guide, such as thecutting tool250 and guide248 described above. As another alternative, theopening334 may be specially configured (such as theopening254 depicted inFIG. 24), and then enlarged (as depicted for theopening254 inFIG. 25).
• InFIG. 32 it may be seen that theliner string322 is expanded radially outward. Preferably, at least theliner portion332 is expanded, but the remainder of theliner string322 may also be expanded. Due to expansion of theliner portion332, the outer surface of the liner portion contacts and seals against the inner surface of thewindow330 circumscribing the window. The seal between theliner portion332 and thewindow330 is facilitated by the sealingmaterial336 contacting the inner surface of the window. However, the seal could be formed by other means, such as metal to metal contact between theliner portion332 and thewindow330, without use of the sealingmaterial336, in keeping with the principles of the invention.
• InFIG. 33 it may be seen that theopening334 is expanded to provide enhanced flow and access between the interior of thecasing string324 below thewindow330 and the interior of theliner string322 above the window. Expansion of theopening334 also results in a seal being formed between the exterior surface of theliner portion332 circumscribing theopening334 and the interior of thecasing string324. At this point, it will be readily appreciated that the interiors of the casing andliner strings324,322 are isolated from thewellbores326,328 external to the strings.
• Additional steps in themethod320 may be used to further seal and secure the connection between the liner andcasing strings322,324. InFIG. 34 it may be seen that theliner string322 within thecasing string324 is further outwardly expanded so that it contacts and radially outwardly deforms the casing string. Theopening334 is also further expanded, and aportion338 of theliner string322 may be deformed downwardly into thecasing string324 as the opening is expanded.
• This further expansion of theliner string322, including theopening334, in thecasing string324 produces several desirable benefits. Theliner string322 is recessed into the inside wall of thecasing string324, thereby providing an inner diameter D9 in the liner string which is preferably substantially equal to, or at least as great as, an inner diameter D10 of thecasing string324 above thewindow330. The seal between the outer surface of theliner string322 circumscribing theopening334 and the inner surface of thecasing string324 is enhanced by increased contact pressure therebetween. In addition, another seal may be formed between the outer surface of theliner string322 and the inner surface of thecasing string324 above thewindow330. Furthermore, the downward deformation of theportion338 into thecasing string324 below thewindow330 enhances the securement of theliner string322 to the casing string. As described above, outward elastic deformation of thecasing string324 may be desirable to induce an inwardly biasing force on the casing string when the expansion force is removed, thereby maintaining a relatively high level of contact pressure between the casing andliner strings324,322.
• InFIG. 35 it may be seen that a generally tubularexpandable member340 having anopening342 formed through a sidewall thereof is positioned within thecasing string324 with theopening342 rotationally aligned with thewindow330 and, thus, with aflow passage344 of theliner string322. Themember340 extends above and below theliner string322 in thecasing string324 and extends through theopening334. Themember340 is then expanded radially outward within thecasing string324.
• Expansion of themember340 further secures the connection between the liner andcasing strings322,324. Seals may be formed between the outer surface of themember340 and the interior surface of thecasing string324 above and below theliner string322, and the inner surface of the liner string in the casing string. The seals are preferably formed due to contact between themember340 outer surface and the casing andliner strings324,322 inner surfaces. For example, the seals may be metal to metal seals. The seals may be formed due to a layer of sealing material on themember340 outer surface and/or the casing andliner strings324,322 inner surfaces. However, any types of seals may be used in keeping with the principles of the invention.
• Themember340 may be further expanded to further outwardly deform thecasing string324 where it overlies the member, in a manner similar to that used to expand themember186 in themethod170 as depicted inFIG. 17. In that way, themember340 may be recessed into the inner wall of thecasing string324 and the inner diameter D11 of the member may be enlarged so that it is substantially equal to, or at least as great as, the inner diameter D10 of the casing string. Due to outward deformation of thecasing string324 in themethod320, whether or not themember340 is recessed into the inner wall of the casing string, it may be desirable to delay cementing of the casing string in the parent wellbore326 until after the expansion process is completed.
• Thus have been described themethods10,110,170,200,230,260,280,300,320 which provide improved connections between tubular strings in a well. It should be understood that openings and windows formed through sidewalls of tubular members and structures described herein may be formed before or after the tubular members and structures are conveyed into a well. Also, it should be understood that casing and/or liner strings may be cemented in parent or branch wellbores at any point in the methods described above.
• Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. For example, although certain seals have been described above as being carried on one element for sealing engagement with another element, it will be readily appreciated that seals may be carried on either or neither element. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.

Claims (21)

1-49. (canceled)

50. A method of forming a wellbore junction in a subterranean well, the method comprising the steps of:

drilling a first wellbore;

installing a casing string in the first wellbore;

drilling a second wellbore extending outwardly from the first wellbore;

aligning a window formed through a sidewall of the casing string with the second wellbore;

positioning a member within the casing string;

forming an opening through a sidewall of the member, the opening having projections extending into the opening;

folding the projections outward into the window; and

then installing a liner string through the opening and into the second wellbore.

51. The method according toclaim 50, wherein the opening forming step is performed before the member positioning step, and wherein the positioning step further comprises aligning the opening with the window.

52. The method according toclaim 50, wherein the opening forming step is performed after the member positioning step.

53. The method according toclaim 50, further comprising the step of expanding the member within the casing string.

54. The method according toclaim 53, wherein the member expanding step is performed after the member positioning step.

55. The method according toclaim 53, wherein the member expanding step is performed before the folding step.

56. The method according toclaim 53, wherein the expanding step further comprises sealing between the member and the casing string.

57. The method according toclaim 56, wherein the sealing step further comprises forming a metal to metal seal between the member and the casing string.

58. The method according toclaim 56, wherein the sealing step further comprises providing a sealing material between the member and the casing string.

59. The method according toclaim 53, wherein the casing string includes a tubular structure having the window formed therein, and wherein the expanding step further comprises expanding the member within the tubular structure.

60. The method according toclaim 59, wherein the expanding step further comprises expanding the member into a radially enlarged portion of the tubular structure, so that an internal dimension of the member is greater than or equal to a minimum internal diameter of the casing string above the window.

61. The method according toclaim 59, wherein the expanding step further comprises sealing between the member and the tubular structure.

62. The method according toclaim 61, wherein the sealing step further comprises forming a metal to metal seal between the member and the tubular structure.

63. The method according toclaim 61, wherein the sealing step further comprises providing a sealing material between the member and the tubular structure.

64. The method according toclaim 50, wherein in the liner string installing step, the liner string has an outer diameter greater an inner dimension of the opening, the liner string thereby enlarging the opening as the liner string passes through the opening.

65. The method according toclaim 64, wherein the enlarging step further comprises sealing between the liner string and the member in the opening.

66. The method according toclaim 65, wherein the sealing step further comprises forming a metal to metal seal between the liner string and the member about the opening.

67. The method according toclaim 65, wherein the sealing step further comprises providing a sealing material between the liner string and the member in the opening.

68. The method according toclaim 65, wherein the sealing step further comprises isolating an interior of the casing string from the first and second wellbores external to the casing string.

69. The method according toclaim 50, further comprising the step of cutting off an upper end portion of the liner string extending inwardly through the opening, after the step of installing the liner string.

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