Description

APPARATUS AND METHOD FOR EXPANDING TUBULAR ELEMENTS

Technical field

[0001] This invention relates to methods and apparatus for expanding tubular elements such as casing or other tubulars that are typically installed in wells such as oil or gas wells, or tubulars of surface, subsea or subsurface pipelines. Even further the invention relates to systems which employ such methods and apparatus for expanding tubular elements.

Background art

[0002] Tubular elements such as casing and completion tubing, screens and other such devices are well known in the field of oil and gas wells. In order for them to be installed in the well, it is necessary that they have an outer diameter that is less than the inner diameter of the borehole in which they are to be installed. In fact, since the inner diameter of the borehole can vary and the trajectory of the borehole is often not straight, the maximum possible diameter can be significantly less than that of the borehole at any point.

[0003] When a borehole is being drilled, it is usually necessary to stop drilling after a certain depth and stabilise the borehole by placing a steel tubular casing in the well and filling the annulus between the outside of the casing and the borehole wall with cement. This operation may need to be repeated several times during the drilling of the well, each successive casing being necessarily smaller than the inside diameter of the preceding casing. This in turn leads to progressive reduction of the inner open diameter of the well which in turn places limitations on the quantities of fluids that can flow along the well and the depth to which the well can be drilled.

[0004] To overcome this problem, it has been previously proposed to expand the casing in the well to reduce the annular space. Also, expansion of subsequent casings to match the diameter of the previous casing has also been proposed to avoid the progressive diameter reduction found with conventional casing techniques.

[0005] Expansion is typically achieved using a cone shaped expansion tool which has a maximum diameter that is greater than the inside diameter of the casing to be expanded. Forcing the expansion tool through the casing causes it to expand. One difficulty in this operation is that because the outer diameter of the expansion tool is greater than the inner diameter of the casing, it is not possible to position the expansion tool in the casing; it must either start at the top or bottom and be moved either to the other end or back to its starting place to be removed from the casing. To address this, expansion tools have been proposed that are initially positioned in a contracted state and then are reconfigured into their operational or deployed configuration before being moved and forged through the casing. However, since the deployed outer diameter is still greater than the inner diameter of the casing, this must be done in an open section of the well or in a section of wider diameter, since the forces used in deployment are normally not large enough to expand the tubular.

[0006] It is an object of this invention to provide a method and apparatus by which expansion can be initiated in a section of the casing or other tubular in its unexpanded state and so can create either a complete expansion, or a chamber in which a conventional expandable cone can be deployed. This invention achieves this object by the use of a compressible member on an expanding tool that can be squeezed to provide an expansion surface on an expansion tool that can fit in the unexpanded tubular element.

[0007] It is further an object of this invention to provide various applications of the expansion apparatus, some of which reduce the need for the use of cementing in wells.

Disclosure of the invention

[0008] One aspect of this invention provides an apparatus for expanding tubular elements, comprising:

- a tool body;

- an axially compressible expansion body mounted on the tool body such that the outer surface of the expansion body is substantially the same outer diameter as that of the tool body; and

- means for axially compressing the expansion body such that its outer surface is expanded beyond the outer diameter of the tool body.

[0009] In one form of the invention the expansion body may comprise one or more rings. In another form of the invention the expansion body may comprise a cylinder. The expansion body can be mounted coaxially on a longitudinal axis of the tool body. Typically the expansion body is made from a flexible and elastic material such as polyurethane. In one form of the invention the expansion body may be comprised of more than one section.

[0010] The means for axially compressing the expansion member can comprise a pair of surfaces on the tool body arranged such that the expansion body can be squeezed therebetween. In one embodiment, the pair of surfaces comprises a first surface that is fixed on the tool body and a second surface that is moveable of the tool body. In one form of the invention the first surface and the second surface may be substantially perpendicular to the longitudinal axis of the tool body. In another form of the invention the first surface and the second surface may be at different angles to the longitudinal axis of the tool body.

[0011] The tool body can also comprise a cylinder in which a piston is slidably located, the second surface being formed on the piston. The cylinder is preferably provided with a supply of pressurised fluid (either from surface or via a downhole pump) for causing movement of the piston. Alternatively, the cylinder may have a mechanical arrangement for causing movement of the piston, such as a screw and thread type arrangement.

[0012] In one embodiment, the first surface is fixed to the body by means of an axial shaft around which the expansion body and piston are mounted.

[0013] The apparatus can further comprise means such as a cable for moving the tool body through the tubular element. Alternatively, a "workstring", comprising coiled tubing, drillpipe or other conduit can be used to move the tool body through the tubular element.

[0014] Another aspect of the invention provides a method for expanding tubular elements, comprising:

- positioning an apparatus as claimed in any preceding claim at a

predetermined position in the tubular element; and - compressing the expansion body such that its outer surface expands against the inner wall of the tubular element and causes it to expand and deform permanently.

[0015] It will be understood that permanent deformation is also known as plastic deformation in the art, wherein the deformation is beyond the elastic limit.

[0016] In a stationary mode (i.e. without movement of the apparatus in its expanded form), this can be used to reduce compaction stresses in casing. This can take place with or without a sleeve/sheet in between the expansion body and the tubular element.

[0017] The method preferably comprises moving the apparatus with the expansion body in its compressed configuration along the tubular element to progressively expand and permanently deform a length of the tubular element.

[0018] This dynamic mode may require a lubricant which can be a liquid or a sheet or a coating to the inside of the tublar element to ease movement of the apparatus in its expanded form.

[0019] Releasing the expansion body from compression such that it returns to its uncompressed shape allows movement of the tool body to another location in the tubular element. Expansion of the tubular element at the other location can then be repeated. This can be done at a number of locations in the tubular element.

[0020] The method of the invention is preferably applied to the expansion of tubular elements such as casing or completion or production tubulars installed in wells such as oil or gas wells. It can be used for expansion of the tubular against the borehole wall or against another casing or liner. Alternatively, it can be used to create a bell or expanded region such as a chamber in which another expansion tool can be deployed for further expansion of the tubular. Another application can be to clad a relatively thin steel tube (with or without seals on the outside) against the inside of a deteriorated old tubing, casing, leaking connector, perforation, etc.

[0021] An application of the apparatus of the invention may be for a device to produce one or more areas of isolation. The areas may be in the annulus

of a well or the areas may be selected areas in a tubular of a well. The method of producing these areas of isolation is attained by the expansion of tubular elements in the areas of interest.

[0022] Another aspect of the invention provides for a liner hanger including an apparatus for expanding tubular elements as described above.

[0023] Another aspect of the invention provides for a fishing tool including an apparatus for expanding tubular elements as described above. The fishing tool may further include a conduit. This conduit may allow for circulation through the fishing tool. The conduit may further allow for circulation through the article to be fished.

[0024] Another aspect of the invention provides for a wellhead including an apparatus for expanding tubular elements as described above. The apparatus may be used to expand more than one concentric tubular element.

[0025] Another aspect of the invention provides for an abandonment plug including an apparatus for expanding tubular elements as described above. The apparatus may be used to expand a tubular element in a well to be abandoned. This tubular element may be an additional tubular element inside the casing or liner. The expansion body may be left in an expanded state in the expanded tubular element to form the abandonment plug. The additional tubular element may be expanded so as to close the micro-annulus around the casing or liner.

[0026] Another aspect of the invention provides for an expandable sand screen including an apparatus for expanding tubular elements as described above.

[0027] Another aspect of the invention provides for a well pressure tester including an apparatus for expanding tubular elements as described above. The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of a compressible expansion body substantially to form a seal against the tubular element.

[0028] Another aspect of the invention provides for a pile expander including an apparatus for expanding tubular elements as described above.

[0029] Another aspect of the invention provides for a bridge plug including an apparatus for expanding tubular elements as described above. The bridge plug may be permanent or it may be retrievable. This tubular element to be expanded may be an additional tubular element inside the casing or liner. The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of a compressible expansion body substantially to form a seal against the tubular element.

[0030] Another aspect of the invention provides for a packer including an apparatus for expanding tubular elements as described above. This tubular element to be expanded may be an additional tubular element inside the casing or liner. The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of a compressible expansion body substantially to form a seal against the tubular element.

[0031] Another aspect of the invention provides for a pipe connector including an apparatus for expanding tubular elements as described above. Preferably the pipe connector is a swage type pipe connector.

[0032] Another aspect of the invention provides for a selective chemical placement tool including an apparatus for expanding tubular elements as described above. The selective chemical placement tool may be slidably displaceable.

[0033] Another aspect of the invention provides for an anchor device including an apparatus for expanding tubular elements as described above. The anchor device may be used to anchor a tubular element or other equipment against the formation or another tubular element.

[0034] Another aspect of the invention provides for a bellow expander including an apparatus for expanding tubular elements as described above. The bellow expander may be used to relieve buckling or axial stresses in the tubular element.

[0035] Another aspect of the invention provides for a downhole patching system including an apparatus for expanding tubular elements as described above. The downhole patching system may be used to repair casing or liner damage, or leaking connectors. It may further include a sealing element.

[0036] Another aspect of the invention provides for a perforation shut off patch system including an apparatus for expanding tubular elements as described above. The perforation shut off patch may further include a sealing element. [0037] Another aspect of the invention provides for a telescopic liner expansion system including an apparatus for expanding tubular elements as described above.

[0038] Other uses will be apparent from the description below. Brief description of the drawings [0039] Figure 1 shows a schematic side view of an apparatus according to one embodiment of the invention;

Figure 2 shows a schematic side view of detail of the head section of the apparatus of Figure 1 ;

Figure 3 shows a schematic side view of detail of the head section of the apparatus of Figure 1 in a different position;

Figure 4 shows a schematic side view of the apparatus of Figure 3 in situ;

Figure 5 shows a schematic side view of the apparatus of Figure 4 in an expanded section of casing;

Figure 6 shows a schematic side view of a liner lap expansion application of the apparatus of the invention;

Figure 7 shows a schematic side view of an application of the apparatus of the invention used to pressure test a liner lap and then used to pressure test the liner;

Figure 8 shows a schematic side view of a pressure tester application of the apparatus of the invention; and

Figure 9 shows schematic side view of a liner bottom expansion application of the apparatus of the invention. Mode(s) for carrying out the invention [0040] Figure 1 shows an apparatus or tooMO according to one embodiment of the invention suspended in a tubular 12 such as a well casing by means of a wireline cable 14 providing power and data communication as well as physical support. The apparatus of tool 10 comprises a tool body 16 which is provided with power and control electronics, a pump and

hydraulic fluid supply and sensors (not shown). An operational head section 18 is provided at the lower end of the tool body 16. Tool 10 may also optionally in a central bore section to allow for circulation (not shown).

[0041] It will be understood that tubular 12 may be one of a number of tubular elements used in oil or gas wells such as, for example, a casing, a liner, a pipeline, or the like. Tubular 12 may also be one of a number of types of tubulars used in surface, subsea or subsurface pipelines. It will also be understood that tubular 12 may be of a solid, slotted or perforated type.

[0042] Figure 2 shows detail of the head section 18 which comprises a main head part 20 which is connected to the tool body 16 and defines a cylinder 22 open at its lower end. An axial shaft 24 extends from the base of the cylinder 22 and has an end plate 26 connected thereto. A piston 28 is slidably mounted in the cylinder 22 around the shaft 24. The head 30 of the piston 28 has a larger diameter than the part 32 received in the cylinder bore 22, the outer diameter of the head 30 corresponding approximately to the outer diameter of the tool body 16. A polyurethane ring 34 is mounted around the shaft 24 between the piston head 30 and the end plate 26. This too has an outer diameter corresponding approximately to the outer diameter of the tool body 16. The working space 36 in the cylinder 22 below the piston 28 is connected to a supply of pressurised fluid (not shown) in the tool body 16.

[0043] It will be noted that in other embodiments of the invention instead of having a ring 34 there may be a thick walled cylinder mounted around the shaft 24 between the piston head 30 and the end plate 26, and this cylinder may serve as an expansion body in tool 10. The material from which the ring 34 or the cylinder is made may be other kinds of flexible and elastic material such as, for example, rubber. Further, the ring 34 or the cylinder may be comprised of more than one section, which may form separate segments. These segments may be housed in compartments specifically shaped therefore in the area around the shaft 24, between the piston head 30 and the end plate 26.

[0044] In the position shown in Figures 1 and 2, pressurised fluid has not been admitted to the working space 36 and the ring 34 is uncompressed. Thus

the tool 10 has a substantially constant outer diameter and can be run in the casing 12 to any location of interest. In this example, the tool 10 is used to make a 'bell' or section of enlarged diameter know as a chamber in the casing 12 such as might be used for deployment of a conventional expanding tool.

[0045] When the tool 10 is positioned at the bottom of the section to be expanded, pressurised fluid is admitted to the working space 36. This forces the piston 28 out of the cylinder 22 so as to squeeze the ring 34 between the head 30 and end plate 26. This squeezing action causes the ring 34 to bulge around its periphery 38 so as to project beyond the outer diameter of the rest of the tool 10 (as is shown in Figure 3). The peripheral bulge 38 of the ring 34 causes the casing 12 to be deformed permanently 40 as is shown in Figure 4.

[0046] With the ring 34 held in its squeezed state, the tool 10 is then advanced through the casing 12 (in direction z in Figure 5), the squeezed ring forcing the casing 12 to expand permanently 40 as the tool 10 is moved (see Figure 5). Once the appropriate length L of casing 12 has been expanded, pressure on the ring 34 is released by venting fluid from the working space 36. The ring 34 then returns to its unexpanded position (as shown in Figures 1 and 2), and the tool 10 can be moved to another position in the unexpanded parts of the casing 12. In this dynamic mode, the maximum thickness of tubular elements expandable by this technique will depend on the maximum force that can be applied by the cable. The presence of a lubricant and or sleeve will also have an impact.

[0047] In an alternative embodiment the tool can be moved downwards, for example, by using a heavy drillstring in a near vertical well.

[0048] In the embodiment described above, the tool 10 is lowered to its start depth on the cable 14, or by coiled tubing, pipe, as the case may be and then raised to expand the length L of casing 12. It is also possible to start the expansion at the top of the section of casing and force the tool down, for example by pumping pressurised fluid into the casing above the tool 10.

[0049] Various alternatives are also available to the piston and cylinder arrangement described for squeezing the ring. For example, various types of mechanical arrangements may be used such as a powered screw and nut or rack and pinion arrangement can be used either to move a piston in the manner described above or, alternatively, to hold the 'piston' still and draw the end plate towards it to obtain the same effect.

[0050] Various sensors can be provided in the tool to monitor its operation and provide feedback, typically via the cable, to allow accurate control of the tool in use.

[0051] While the example given above is related to forming a chamber or bell in the casing 12, this invention can find uses in a number of applications. For example, rather than just expanding a section of the casing to be used for deployment of another expanding tool, it can be used as the primary expansion method for the whole casing. Also, its ability to be released and moved through the unexpanded casing means that it can be used for providing a number of locally expanded sections of the casing separated by unexpanded sections. The expansion provided can be used in the manner of previously proposed expansions, for example, to avoid cementing and progressive reduction in the flow diameter of the well, connection of sections of casing, forming of expanded sections for insertion of a succeeding casing section, expansion of a patch over open borehole or existing casing, etc. Optionally a sealing element such as an o-ring or coating may be placed over the expansion body to give a more resilient seal.

[0052] In an alternative embodiment the expansion body being one or more rings 34 or one or more sleeves may be enclosed in a protective cover such as a cage arrangement which is used to provide the expansion body with more wear resistance and a longer lifespan. Instead of a complete cover around the expansion body, there may be sections of the expansion body covered by a protective layer of material to improve wear resistance.

[0053] The expansion effect may vary according to the dimensions of the tool, in particular the dimensions of the polyurethane ring. A thicker ring will allow potentially greater expansion from the original diameter, as will a larger

plunger or bore stroke. While polyurethane is the preferred material for the ring due to its resilience, in particular its ability to return to its original dimensions after compression is released, as well as its greater wear ability, impact resistance and greater operational temperature range, other similar materials may be used. Polyurethane is also sufficiently smooth to be able to slide over the casing surface as the tool is moved in its expanded form. A lubricant/teflon-sheet or both can be provided to assist in this, green soap being preferred.

[0054] The invention may also be used to form one or more localised expansions, such as is shown in Figure 4. A single expansion like this can be used to anchor tubular members together (hangers). A series of these placed relatively closely together can be used for stress relief or to prevent buckling should the tubular be deformed following installation or later in the lifetime of a well. This deformation may be for a variety of reasons such as, for example, the depletion of a well leading to compaction. By leaving the head section in place as is shown in Figure 4, the whole tool 10 can serve as an anchor to provide a reaction to allow movement of another tool connected to it through the well. Reinforcement may be required for effective use in dynamic expansion and for better grip, such as in the required in a bridge plug or packer. Cutters, wear resistant pads, etc can be mounted/cast within the ring. Also, multiple rings may be expanded by one or more pistons. Other uses and variations of the technique will be apparent.

[0055] Another application of the apparatus of the invention is for a downhole anchor device. The anchor device may be used to anchor a tubular element or other equipment against the formation or another tubular element at selected locations in the wellbore.

[0056] The invention may be applied to expansion of tubular elements against the borehole wall or against another casing. In this way the invention can extend to a telescopic liner expansion system which includes the apparatus for expanding tubular elements as described above. Three liners, for example, can be run down a hole at the same time, one inside

the other. Each liner can then be extended and the apparatus for expanding tubular elements used to expand each of them.

[0057] The invention may also be used to form a bell or expanded section, known as a chamber in the art, in which another expansion tool can be deployed for further expansion of the tubular. The bell or expanded section, or chamber, may be used for other purposes as well in drilling or completion operations in oil or gas wells. Expanded section 40 shown in Figure 5 is an example of such a chamber. The shape of the bell or expanded section, or chamber that is formed may be symmetrical or asymmetrical. Asymmetrical expansion may be accomplished by using a ring 34 which has an asymmetrical shape such as an oval shape. In this case the piston head 30 and the end plate 26 must first be centralised, so that the ring 34 does not move into a position to give symmetrical expansion during use. One of the ways in which asymmetrical expansion is beneficial is when it is used to create a weak point or a specific crack in the casing so that a side passage can be put into the casing at that point.

[0058] The bell or expanded section could be used to locate anything that would otherwise cause a restriction downhole. The apparatus would have to be centralised firmly when used in this way. It could thus, for example, be used to house a sub-surface safety valve, pump, separator, etc.

[0059] Another application of the apparatus for expansion of tubular elements can be to clad a relatively thin steel tube (with or without seals on the outside) against the inside of a deteriorated old tubing, casing, leaking connector, perforation, etc. Substantially smaller sections or larger sections of tubular can be clad by the apparatus. The cladding may, for example, be used to store carbon dioxide gas in a depleted reservoir, enlarge production tubing or repair leaks.

[0060] A further similar application of the apparatus is that it can be used to create a patch or pad downhole for holding sensors that are focused in one direction close to a borehole wall. Similar applications of the apparatus are for a downhole patching system and a perforation shut off patch system. The downhole patching system may be used to repair casing or liner damage, or leaking connectors. The patching system may

further include a sealing element, such as an o-ring on the outer diameter (OD).

[0061] The apparatus may also be used in the expansion of tubular elements to produce areas of isolation. These areas may be in the annulus of a well or these areas may be at selected zones of a well. These zonal areas of isolation, for example, can be used to squeeze off selective sections for shut off, acid injections, chemical sand consolidation, or the like.

[0062] Another application of the apparatus may be for a sand screen.

[0063] Yet a further application of the apparatus is for a pile expander. The advantage of such a pile expander is that it can improve pile bearing capacity and thus shorter piles may be used.

[0064] A further application of the apparatus of the invention is for a liner hanger. The liner hanger may be for use with liners, casing or tubing, as the case may be. In this application the apparatus is preferably used with a sleeve in combination with a sealing element such as an o-ring on the OD.

[0065] In Figure 6 a similar application for use in expanding an expandable liner lap 42 is illustrated.

[0066] Another application of the apparatus of the invention is for an expandable fishing tool. The expandable fishing tool may include a conduit through its body. This allows for circulation through the fishing tool. The conduit also allows for circulation through the article to be fished. In this case the article is preferable the tubular element and the conduit thus allows circulation through the whole of the tubular element including its bottom end in the wellbore. The expandable fishing tool has the advantage of including a larger surface area, which may even create a recess, and thus there is a better grip for the fish, or article to be fished.

[0067] Another application of the apparatus is for an expandable wellhead. The apparatus may be used to expand more than one concentric tubular element at the wellhead. Preferably there may be four or five concentric elements at the wellhead which are expanded by the apparatus of the invention. The advantage of this expandable wellhead is that it is then more rigid or robust than conventionally formed wellheads, particularly

those used offshore. A further advantage is that a wellhead with a smaller OD can be made.

[0068] The apparatus of the invention may also be used in an abandonment plug. The tubular element that is expanded in the abandonment plug may be an additional tubular element inside the casing or liner. Such an abandonment plug may comprise a tube with one open end and one closed end with or without seals around its OD that is expanded against the casing or liner to shut in the well and simultaneously close the micro- annulus. The expansion used against the casing may be minor and is used to close off the micro-annulus. The apparatus may be used to expand the additional tubular element in a well to be abandoned and the expansion body may be left in an expanded state in the expanded tubular element. The abandonment plug may also include a steel sleeve which is also expanded against the casing together with one or more rings 34. The abandonment plug may be used with or without cement and may be deployed by wireline, coiled tubing or other conduit.

[0069] Another application of the apparatus of the invention is for an expandable sand screen. Similarly the apparatus may also be used in perforated liner and casing expansions.

[0070] As shown in Figures 7 and 8 a further application of the apparatus of the invention is for a well pressure tester. The well pressure tester can be used to pressure test various parts of oil or gas wells such as, for example, a liner lap, the drill pipe, or the formation cementation. The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of an expansion body substantially to form a seal against the tubular element and not to expand the tubular element beyond its original shape. The apparatus of the invention in this application may include a plurality of rings 34 as shown in Figure 8. In this example of a pressure tester 44 some of the rings 34 may be used for a packer application to isolate the area of interest and others may be used to expand against the area of interest so as to perform the actual pressure test. The pressure tester 44 may be lowered downhole by wireline 14 having electrical cabling, or by coiled tubing or workstring. A pump or pressure intensifier

46 is also lowered downhole along with the pressure tester 44 to provide the pressure used in the pressure test. The pressure may also be supplied by an integrated pressure multiplier, or by other means of supplying pressure.

[0071] A packer itself is yet another application of the apparatus of the invention. The packer may be a permanent installation in the wellbore or may be retrievable and it is used to seal the wellbore either permanently or temporarily. The tubular element to be expanded by the expansion apparatus of the packer may be an additional tubular element inside the casing or liner. The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of a compressible expansion body substantially to form a seal against the tubular element and not to expand the tubular element beyond its original shape. The packer may be used in production or for testing, and may be used in cased wellbores or in open wellbores. Typically the packer is used in most completions to isolate the annulus from the production conduit, enabling controlled production, injection or treatment of the wellbore.

[0072] The well pressure tester 44 may also be used as a leakoff test device to test the strength or fracture pressure of the open formation. A section of the wellbore can be sealed off using the apparatus and the pressure tester 44 can then be used along with fluid under pressure in the section to test the maximum fluidic pressure which the well can withstand in that particular section. The leakoff test device may also be used at the liner bottom.

[0073] The apparatus of the invention may also be used to expand the liner bottom 48 to seal the annulus, as illustrated in Figure 9.

[0074] Another application of the apparatus of the invention is for a bridge plug which is used to isolate the lower part of a wellbore. The bridge plug may be permanent, enabling the lower part of the wellbore to be permanently sealed off from production, or it may be retrievable enabling the lower part of the wellbore to be temporarily isolate from the treatment conducted on an upper zone of the wellbore. The tubular element expanded by the bridge plug may be an additional tubular element inside the casing or liner.

The apparatus for expanding tubular elements in the well pressure tester preferably uses expansion of a compressible expansion body substantially to form a seal against the tubular element and not to expand the tubular element beyond its original size. The advantage of the bridge plug is that it may be able to hold more pressure when it is expanded to a level just below the yield of the tubular element. The result is that it will thus will then have more holding force.

[0075] The apparatus may also be used in a pipe connector. Typically a pipe, or tubing or casing is expanded to fit substantially tightly against another pipe, tubing or casing, as the case may be, which has been fitted over it and it is then connected using known pipe connection methods. The pipe connector may also be used to connect tubing to casing or to connect a lateral pipe to a central pipe. Preferably the pipe connector is a swage type pipe connector.

[0076] Another application of the apparatus of the invention is for a selective chemical placement tool. The selective chemical placement tool is typically deployed downhole by coiled tubing, workstring or other conduit. The selective chemical placement tool may be slidably displaceable. In use the selective chemical placement tool is deployed to a particular area of interest and then expansion takes place by the apparatus so that the tool is anchored in the casing or liner across an area to be treated. Chemical fluid is then injected into the body of the tool between its two outer sections and this chemical fluid may then be able to enter areas outside of the casing or liner, that is in the annulus, by squeezing to perform various chemical treatments such as, for example, sand consolidation and chemical shut-off. Once the chemical treatment has been performed the selective chemical placement tool may then be slidably displaced to another location and then be anchored at that position so that another chemical treatment may be performed at this location. In this way the selective chemical placement tool may be moved sequentially down the wellbore to perform sequential chemical treatments where required.

The apparatus may also be used as part of a bellow expander. The bellow expander may be used to relieve buckling or axial stresses in a tubular element. It may further also be used to convert global buckling of a pipe or casing to localised buckling.