A multi-layered wellbore junction. In a described embodiment, a method of forming an expanded chamber in a subterranean well includes the steps of: positioning multiple chamber sidewall layers in the well; and expanding the layers in the well to form the expanded chamber.

BACKGROUND

The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a multi-layered wellbore junction.

Significant difficulties have been experienced in the art of forming expanded chambers within a well. For example, a wellbore junction constructed out of welded-together single layer metal sheets at the surface may be collapsed (laterally compressed) at the surface prior to running it into a well. The junction may then be reformed (expanded) to its approximate uncompressed configuration in the well.

Unfortunately, the expanded junction may not have sufficient burst and collapse pressure ratings due to several factors. One of these factors may be work hardening of the metal material when it is collapsed at the surface and then expanded downhole. Another factor may be imperfect reforming of the junction to its original shape.

Therefore, it may be seen that improved methods of expanding wellbore junctions and improved wellbore junction configurations are needed. Such methods and configurations may be used in other applications as well. For example, an expanded chamber in a well may be useful for other purposes, such as oil/water separation, downhole manufacturing, etc.

SUMMARY

In carrying out the principles of the present invention, in accordance with an embodiment thereof, an expandable wellbore junction is provided which solves at least some of the above problems in the art.

In one aspect of the invention, a subterranean well system is provided which includes a chamber expanded within the well. The chamber has a sidewall made up of multiple layers.

In another aspect of the invention, a method of forming an expanded chamber in a subterranean well is provided. The method includes the steps of: positioning multiple chamber sidewall layers in the well; and expanding the layers in the well to form the expanded chamber.

In yet another aspect of the invention, a wellbore junction for use in a subterranean well is provided. The wellbore junction includes a sidewall made up of multiple layers expanded in the well. In still another aspect of the invention, the wellbore junction includes a sidewall made of a single layer of composite material.

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.

DETAILED DESCRIPTION

Representatively illustrated inFIGS. 1A–Cis a subterranean well system10which embodies principles of the present invention. In the following description of the system10and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used 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 inFIGS. 1A–C, a wellbore12has been drilled, and then underreamed to form an enlarged cavity14. A tubular string16, such as a casing, liner or tubing string, is conveyed into the wellbore12. At a lower end of the tubular string16, a generally tubular outer shell18in an unexpanded configuration is positioned in the underreamed cavity14.

The outer shell18may at this point be collapsed or compressed from an initial expanded configuration at the surface. Alternatively, the outer shell18may be initially constructed in the unexpanded configuration.

The outer shell18may be made of any type of material. Preferably, the outer shell18is made of metal or a composite material. In addition, the outer shell18is preferably capable of holding pressure, so that it can be expanded by increasing a pressure differential from its interior to its exterior (e.g., by applying increased pressure to its interior). However, it should be clearly understood that any method of expanding the outer shell18may be used in keeping with the principles of the invention. For example, the outer shell18could be expanded by mechanically swaging it outward, drifting, etc.

An inner shell20is positioned within the tubular string16. The inner shell20may be conveyed into the wellbore12at the same time as the outer shell18, or it may be conveyed into the wellbore after the outer shell. For example, the inner shell20could be conveyed through the tubular string16after the outer shell18is expanded in the wellbore12.

The inner shell20is constructed with two generally tubular legs22at its lower end, since the system10in this embodiment is used for constructing a wellbore junction downhole. Thus, the inner shell20has an inverted somewhat Y-shaped configuration with two wellbore exits24at its lower end and a single interior passage26and tubular string connection27at its upper end. However, the inner shell20could have any number of wellbore exits24, and the inner shell could be otherwise configured, in keeping with the principles of the invention. For example, the inner shell20could be shaped similar to the outer shell18, or with no wellbore exits, etc.

As with the outer shell18, the inner shell20could be made of any type of material, but is preferably made of metal or a composite material. The inner shell20is preferably capable of holding pressure, so that it may be expanded by inflating it, but any expanding method may be used as an alternative to inflation, such as mechanical swaging, drifting, etc. The inner shell20could be mechanically swaged, drifted, etc. after it is expanded by inflating, for example, to ensure that its legs22and wellbore exits24have a desired shape, such as a cylindrical shape, for improved sealing thereto and/or for improved access therethrough.

Furthermore, the inner shell20in its unexpanded configuration as depicted inFIGS. 1A–Cmay be collapsed or compressed from an initial expanded configuration, or it may be initially formed in its unexpanded configuration.

Referring additionally now toFIGS. 2A–C, the system10is representatively illustrated after the outer shell18has been expanded in the cavity14. As described above, this expansion is preferably accomplished by inflating the outer shell18. Note that the inner shell20remains in the tubular string16above the outer shell18while the outer shell is expanded. However, the inner shell20could be positioned in the outer shell18before, during and/or after the outer shell is expanded.

Referring additionally now toFIGS. 3A–C, the system10is representatively illustrated after the inner shell20has been displaced into the outer shell18. Preferably, the inner shell20is suspended from another tubular string28within the tubular string16, in which case the inner shell may be conveniently displaced into the outer shell18by lowering the inner tubular string28from the surface. However, it should be understood that any method of displacing the inner shell20into the outer shell18may be used in keeping with the principles of the invention.

A seal30may be formed between the inner and outer shells18,20when the inner shell20is displaced into the outer shell18. The seal30may be a metal-to-metal seal formed by contact between the inner and outer shells18,20, or any other type of seal may be used, such as elastomer seals, non-elastomer seals, etc.

Referring additionally now toFIGS. 4A–C, the system10is representatively illustrated after the inner shell20has been expanded within the outer shell18. As described above, the inner shell20may be expanded by inflating, or by any other method. Note that the legs24now diverge somewhat from each other, so that additional wellbores (not shown) drilled from the wellbore exits22will be directed away from each other. In addition, note that although the inner shell20has been expanded within the outer shell18, there remains a space32between the inner and outer shells.

Referring additionally now toFIGS. 5A–C, the system10is representatively illustrated after a load bearing material34has been positioned in the space32between the inner and outer shells18,20. Preferably, the load bearing material34is initially in a liquid state and is pumped into the space32while it is liquid. Eventually, the material34solidifies and forms a load bearing support for the inner and outer shells18,20. The seal30prevents the material34from flowing into the interior of the tubular string16above the outer shell18.

Note that the material34may be positioned in the outer shell18before or after displacing the inner shell20into the outer shell. Furthermore, the material34could be positioned in the space32before or after the inner shell20is expanded within the outer shell18. The material34could be positioned within the outer shell18before or after the outer shell is expanded, and additional material could be added within the outer shell while it is being expanded (e.g., the outer shell could be inflated while the material is pumped into the outer shell). Thus, the order of the steps described herein may be varied, without departing from the principles of the invention.

In one method, the load bearing material34could be positioned within the outer shell18when it is initially run into the well. Later, when it is desired to inflate the outer shell18, additional material34could be positioned within the outer shell.

Referring additionally now toFIGS. 6A–C, the system10is representatively illustrated after the tubular string16and expanded inner and outer shells18,20have been cemented in the wellbore12. To displace cement36into an annulus38between the wellbore12, and the tubular string16and the expanded outer shell18, a drill (not shown) may be used to drill an opening through a lower end of one of the legs24, through the material34, and through the outer shell. The cement36may then be flowed downward through the tubular string28and outward through the drilled opening into the annulus38. Preferably, a tubular work string or cementing string (not shown) would be lowered through the tubular string28and sealed in the one of the legs24having the opening drilled through its lower end, in order to flow the cement36out into the annulus38.

It may now be appreciated that a chamber in the shape of a wellbore junction40has been formed by the inner and outer shells18,20, and the load bearing material34between the shells. The wellbore junction40has been cemented in the wellbore12(in the underreamed cavity14), and additional wellbores can now be drilled by conveying drills, etc. through the wellbore exits22.

However, it should be clearly understood that the wellbore junction40is only one example of a variety of chambers, vessels, etc. that may be constructed downhole using the principles of the invention. For example, a chamber could be constructed downhole which does not have the two legs22or wellbore exits24at a lower end thereof. Instead, the chamber could be sized and shaped to house an oil/water separator, or a downhole factory, etc.

Referring additionally now toFIG. 7, another system50embodying principles of the invention is schematically and representatively illustrated. The system50is similar in many respects to the system10described above, and so elements depicted inFIG. 7which are similar to those described above are indicated using the same reference numbers.

One substantial difference between the systems10,50is that, in the system50, multiple wellbore junctions52,54are formed downhole. Specifically, the outer tubular string16has multiple outer shells56connected at a lower end thereof, and the inner tubular string28has a corresponding number of inner shells58connected at a lower end thereof. Only two wellbore junctions52,54are depicted inFIG. 7, but any number of wellbore junctions may be formed in keeping with the principles of the invention.

A packer60(or other type of annular barrier) is used to seal off the annulus38between adjacent pairs of the outer shells56, and to secure the wellbore junctions52,54in the wellbore12. Note that the wellbore12is not underreamed in the system50, but it could be underreamed, if desired. In addition, use of the packer60is not necessary. For example, if it is desired to cement the junctions52,54in the wellbore12at the same time, or for some other reason isolation of the wellbore between the junctions is not required, the packer60may not be used.

It may be convenient to form the wellbore junctions52,54separately or simultaneously. For example, the outer shells56could be expanded at the same time, or they could be separately expanded. The inner shells58could be displaced into the expanded outer shells56at the same time, or they could be separately displaced (for example, one inner shell58could be displaced while the other inner shell remains stationary). The inner shells58could be expanded at the same time, or they could be separately expanded. The material34could be positioned in the wellbore junctions52,54at the same time, or it could be positioned in the wellbore junctions separately.

Note that the wellbore junction54has a seal30between the inner and outer shells56,58both at the upper and lower ends of the junction. The seals30may be used to contain the material34between the inner and outer shells56,58of the junction54when the material is separately positioned in the junctions52,54. The seals30between the junctions52,54may not be needed if the material is to be positioned simultaneously in each of the junctions. However, if the junctions52,54are separated by hundreds or thousands of feet in the wellbore, the seals30between the junctions can be used to reduce the amount of load bearing material34required (i.e., it may not be necessary to use the material between the seals).

Another difference between the systems10,50is that each of the wellbore junctions52,54in the system50has three exits22at its lower end. One of the exits22in each of the wellbore junctions52,54is preferably generally inline with the wellbore12and permits access to, and fluid communication with, the wellbore12below the junction. The other two exits22are used to drill lateral or branch wellbores extending outwardly from the wellbore12. Note that it is not necessary for the wellbore junctions52,54to have the same number of wellbore exits22.

As depicted inFIG. 7, a branch wellbore62has been drilled through one of the wellbore exits22of the upper wellbore junction52. In this case, the branch wellbore62has been drilled by cutting an opening68through a sidewall of the junction52at a lower end of one of the legs24(after the inner and outer shells56,58have been expanded, and after the material34has hardened between the inner and outer shells), and then drilling into the earth surrounding the main or parent wellbore12. A liner or other tubular string64is installed in the branch wellbore62and secured at its upper end in the leg24using a liner hanger66or other anchoring device.

To cement the upper wellbore junction52in the wellbore12after the branch wellbore62is drilled, the cement36may be pumped through the liner string64into the branch wellbore, and then from the branch wellbore into the annulus38between the junction52and the wellbore12. Alternatively, the wellbore junction52could be cemented in the wellbore12prior to drilling the branch wellbore62, as described above.

A variety of different methods for cementing the liner string64in the branch wellbore62may be used, or the liner string could be left uncemented in the branch wellbore if desired. Screens or slotted liners may be run with the liner string64, with or without external casing packers and/or the screens/slotted liners may be gravel packed or expanded in the branch wellbore62. Any method of completing the branch wellbore62may be used in keeping with the principles of the invention.

Note that the upper wellbore junction52has the outwardly extending legs24directly opposite each other, while the lower wellbore junction54has the outwardly extending legs longitudinally spaced apart. Thus, it is not necessary for the wellbore junctions52,54to be identical in the system50. The wellbore junctions52,54may be similar, or they may be substantially different, and they may be configured differently from they way they are depicted inFIG. 7(e.g., having more or less wellbore exits22, etc.), in keeping with the principles of the invention.

Referring additionally now toFIG. 8, each of the wellbore junctions40,52,54has been described above as having a sidewall70made up of multiple layers72,74,76.FIG. 8depicts an enlarged view of such a sidewall70apart from the remainder of the systems10,50. In the junction40of the system10described above, the outer layer72is the outer shell18, the inner layer74is the inner shell20, and the middle layer76is the material34. In each of the junctions52,54of the system50described above, the outer layer72is the outer shell56, the inner layer74is the inner shell58, and the middle layer76is the material34.

The inner and outer layers72,74are preferably made of metal, such as steel, aluminum, etc. However, the layers72,74could be made of a composite material, such as a resin or rubber impregnated fabric. The fabric could be a woven or braided material and could be a carbon fiber fabric. The resin could be a “B-staged” resin which crosslink catalyzes when exposed to a predetermined elevated temperature downhole. A suitable composite material is described in U.S. Pat. No. 5,817,737, the entire disclosure of which is incorporated herein by this reference.

The inner and outer layers72,74, or either of them, could be made of a rubber material, so that they are impervious to the material34(layer76) in its liquid state. For example, the layers72,74could be made of a rubber coated or rubber impregnated fabric composite material. The fabric could be preformed, so that the layers72,74will have the intended shapes (e.g., the inner shell20being Y-shaped with the legs22formed at its lower end, etc.) when the layers are inflated in the well.

If the inner layer74is made of a composite material, then it may be advantageous to provide a protective metal liner within the inner layer, in order to shield it from wear or other damage resulting from tools passing through the junction, to protect it from erosion due to fluids flowing through the junction, etc.

It is not necessary for the inner and outer layers72,74to be made of the same material. For example, the inner layer74could be made of a metal, while the outer layer72could be made of a composite material, or vice versa.

The middle layer76is preferably used to provide load bearing support to the inner and outer layers72,74. Preferably, the middle layer76is a hardenable load bearing material which is initially in a liquid or flowable state. The material76is flowed or otherwise positioned between the inner and outer layers72,74, and then the material is hardened. For example, the middle layer76could be a latex cement, a hardenable polymer, an epoxy, another bonding material, a polyurethane or a polyethylene material. If the material is an epoxy, it could be a multiple part epoxy which is initially positioned between the inner and outer layers, and then the parts are mixed in the well to cause the epoxy to harden. The middle layer76could be a metal, such as a white metal, lead, tin, a metal matrix composition, etc.

The middle layer76may be positioned at any time within the outer layer72, and may at any time be positioned between the inner and outer layers72,74, before or after the layers72,74(or either of them) are positioned in the well, before or after the layers72,74(or either of them) are expanded in the well, etc. For example, the middle layer76could be a foamed material which is positioned in the outer layer72prior to conveying the outer layer into the well.

The foamed material middle layer76could be shaped (preformed) prior to being positioned in the outer layer72, and/or it could be hardened or rigidized after it is positioned downhole, after the outer layer is expanded, etc. Alternatively, the middle layer76could be initially unfoamed prior to being positioned in the outer layer72, and then foamed after it is positioned in the outer layer, after it is positioned between the inner and outer layers72,74, after either of the inner and outer layers is expanded, etc. Thus, if the middle layer76is a foamed material, it may be foamed at any time.

A pressure relief valve78may be included in the sidewall70to permit the middle layer76material to escape from between the inner and outer layers72,74to prevent excessive pressure buildup between the inner and outer layers. For example, if the middle layer76material is positioned between the inner and outer layers72,74after expanding the outer layer but prior to expanding the inner layer, then expansion of the inner layer could possibly cause excessive pressure buildup in the middle layer, which could hinder expansion of the inner layer if not for the presence of the relief valve78.

As depicted inFIG. 8, the relief valve78is installed in the outer layer72, so that if pressure in the middle layer76exceeds a predetermined level, the excess pressure will be vented out to the annulus38. Alternatively, the relief valve78could vent the excess pressure to another reservoir (not shown) located elsewhere in the well. The relief valve78could also be otherwise positioned without departing from the principles of the invention.

Referring additionally now toFIG. 9, an alternate sidewall80construction is representatively illustrated. The sidewall80includes an inner layer82made of a composite material, a middle layer84made of a foamed material, and an outer layer86made of a composite material. Note that it is not necessary for the inner and outer layers82,86to be made of the same composite material.

A protective lining88is used within the inner layer82to protect it from wear, erosion, etc. The lining88is preferably made of metal, although other materials may be used if desired. The lining88may be installed within the inner layer82at any time, before or after positioning the inner layer in the well, before or after expanding the inner layer, etc. For example, the lining88may be positioned and expanded within the inner layer82after the inner layer has been expanded in the well.

Referring additionally now toFIG. 10, another sidewall90construction is representatively illustrated. In the sidewall90, multiple layers92are used, with the layers being similar to each other. For example, each of the layers92could be made of metal, or each of the layers could be made of a composite or other type of material.

If the layers92are made of metal, then the layers could be welded or otherwise attached to each other at the surface. For example, a bonding material, such as an epoxy, could be used to bond the layers92to each other.

However, it should be clearly understood that it is not necessary for the layers92to be attached to each other by bonding or welding prior to positioning the sidewall90in the well, or prior to expanding the sidewall in the well. For example, a bonding material could be used to bond the layers92to each other after the sidewall90is expanded in the well.

If the layers92are not bonded to each other prior to expanding the sidewall90in the well, then the layers can displace relative to each other as the layers are expanded. As a result of expanding the layers92, residual compressive stress may be produced in an inner one of the layers, and residual tensile stress may be produced in an outer one of the layers. The layers92can be configured so that they are interlocked to each other after they are expanded, such as by forming interlocking profiles on the layers.

Referring additionally now toFIG. 11, another sidewall100construction is representatively illustrated. The sidewall100includes at least two metal layers102which are bonded to each other by detonating an explosive104proximate the layers. Detonation of the explosive104sends a shock wave106through the layers102, thereby causing the layers to bond to each other.

The layers102could be explosively bonded to each other before or after the layers are positioned in the well. For example, one of the layers102could be expanded in the well, then the other layer could be expanded within the already expanded layer, and then the explosive104could be detonated within the inner layer to thereby bond the layers to each other. A bonding material, such as an epoxy, could be positioned between the layers102prior to detonating the explosive104.

In each of the systems10,50described above, the wellbore junctions40,52,54have sidewalls constructed of multiple layers. It is believed that this multi-layered sidewall construction provides improved burst and collapse resistance, improved ductility and other benefits. However, a suitable wellbore junction or other chamber could be constructed using a single layer of material, such as a composite material.

For example, the inner shell20of the system10could be expanded in the wellbore12without using the outer shell18. The inner shell20could be made of the composite material described in the incorporated U.S. Pat. No. 5,817,737, so that after the inner shell is expanded the elevated downhole temperature would cause the composite material to harden. Additional wellbores could then be drilled extending outward from the wellbore exits24, either before or after the expanded and hardened inner shell is cemented in the wellbore12. Preferably, the expanded inner shell20would be provided with an internal protective lining, such as the metal lining88described 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. 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.