US20070114018A1 - Annular Isolators for Expandable Tubulars in Wellbores - Google Patents

Abstract

The present disclosure addressed apparatus and methods for forming an annular isolator in a borehole after installation of production tubing. Annular seal means are carried in or on production tubing as it is run into a borehole. In conjunction with expansion of the tubing, the seal is deployed to form an annular isolator. An inflatable element carried on the tubing may be inflated with a fluid carried in the tubing and forced into the inflatable element during expansion of the tubing. Reactive chemicals may be carried in the tubing and injected into the annulus to react with each other and ambient fluids to increase in volume and harden into an annular seal. An elastomeric sleeve, ring or band carried on the tubing may be expanded into contact with a borehole wall and may have its radial dimension increased in conjunction with tubing expansion to form an annular isolator.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This is a Divisional Application of U.S. patent application Ser. No. 10/981,822, filed Nov. 5, 2004, entitled “Annular Isolators for Expandable Tubulars in Wellbores which is a divisional of U.S. Pat. No. 6,854,522, issued Feb. 15, 2005, entitled “Annular Isolators For Expandable Tubulars In Wellbores” and claims priority to and hereby incorporates both by reference for all purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
• Not applicable.
BACKGROUND OF THE INVENTIONField of the Invention
• This invention relates to isolating the annulus between tubular members in a borehole and the borehole wall, and more particularly to methods and apparatus for forming annular isolators in place in the annulus between a tubular member and a borehole wall.
• It is well known that oil and gas wells pass through a number of zones other than the particular oil and/or gas zones of interest. Some of these zones may be water producing. It is desirable to prevent water from such zones from being produced with produced oil or gas. Where multiple oil and/or gas zones are penetrated by the same borehole, it is desirable to isolate the zones to allow separate control of production from each zone for most efficient production. External packers have been used to provide annular seals or barriers between production tubing and well casing to isolate various zones.
• It has become more common to use open hole completions in oil and gas wells. In these wells, standard casing is cemented only into upper portions of the well, but not through the producing zones. Tubing is then run from the bottom of the cased portion of the well down through the various production zones. As noted above, some of these zones may be, for example, water zones which must be isolated from any produced hydrocarbons. The various production zones often have different natural pressures and must be isolated from each other to prevent flow between zones and to allow production from the low pressure zones.
• Open hole completions are particularly useful in slant hole wells. In these wells, the wellbore may be deviated and run horizontally for thousands of feet through a producing zone. It is often desirable to provide annular isolators along the length of the horizontal production tubing to allow selective production from, or isolation of, various portions of the producing zone.
• In open hole completions, various steps are usually taken to prevent collapse of the borehole wall or flow of sand from the formation into the production tubing. Use of gravel packing and sand screens are common ways of protecting against collapse and sand flow. More modern techniques include the use of expandable solid or perforated tubing and/or expandable sand screens. These types of tubular elements may be run into uncased boreholes and expanded after they are in position. Expansion may be by use of an inflatable bladder or by pulling or pushing an expansion cone through the tubular members. It is desirable for expanded tubing and screens to minimize the annulus between the tubular elements and the borehole wall or to actually contact the borehole wall to provide mechanical support and restrict or prevent annular flow of fluids outside the production tubing. However, in many cases, due to irregularities in the borehole wall or simply unconsolidated formations, expanded tubing and screens will not prevent annular flow in the borehole. For this reason, annular isolators as discussed above are typically needed to stop annular flow.
• Use of conventional external casing packers for such open hole completions presents a number of problems. They are significantly less reliable than internal casing packers, they may require an additional trip to set a plug for cement diversion into the packer, and they are not compatible with expandable completion screens.
• Efforts have been made to form annular isolators in open hole completions by placing a rubber sleeve on expandable tubing and screens and then expanding the tubing to press the rubber sleeve into contact with the borehole wall. These efforts have had limited success due primarily to the variable and unknown actual borehole shape and diameter. The thickness of the sleeve must be limited since it adds to the overall tubing diameter, which must be limited to allow the tubing to be run into the borehole. The maximum size must also be limited to allow tubing to be expanded in a nominal or even undersized borehole. In washed out or oversized boreholes, normal tubing expansion is not likely to expand the rubber sleeve enough to contact the borehole wall and form a seal. To form an annular seal or isolator in variable sized boreholes, adjustable or variable expansion tools have been used with some success. However it is difficult to achieve significant stress in the rubber with such variable tools and this type of expansion produces an inner surface of the tubing which follows the shape of the borehole and is not of substantially constant diameter.
• It would be desirable to provide equipment and methods for installing annular isolators in open boreholes, particularly horizontal boreholes, which may be carried on tubular elements as installed in a borehole and provide a good seal between production tubing and the wall of open boreholes.
SUMMARY OF THE INVENTION
• The present invention provides apparatus which may be carried on or in tubing as it is run into a wellbore and deployed to form an annular isolator between the tubing and borehole. In a preferred form, the tubing is expandable tubing and the annular isolator is activated or deployed as a result of or in conjunction with expansion of the tubing. In one embodiment, an annular isolator forming material is in a compartment carried with the tubing as it is installed in a borehole and is driven from the compartment to form an annular isolator in conjunction with tubing expansion. The annular isolator forming material may be placed into the annulus between the tubing and borehole wall where it acts as an annular isolator due to its inherent viscosity or as a result of a chemical reaction which converts the material into a viscous, semisolid or solid material in place in the annulus. The material may include several chemical components which react with each other, or may be a single or multiple chemical components, which also react with ambient fluids to form an annular isolator.
• In another form, the present invention includes an inflatable member carried on the outside of a tubing section. Any of the above described annular isolator forming materials may be flowed into the inflatable member to inflate it and form an annular isolator. In one form of the invention, the inflatable member includes multiple sections, which inflate at progressively increasing pressure levels. A section which inflates at the lowest pressure level is designed to expand to fill the largest expected annulus, while the other sections inflate only after the low pressure section contacts a borehole wall. The inflatable member may be inflated with material carried with the tubing in a compartment and driven from the compartment into the inflatable member as a result of tubing expansion. It may also be inflated with material pumped down the tubing itself or through a work string positioned in the tubing.
• In another form of the invention, the annular isolator forming material is an elastomeric sleeve, band or ring carried on expandable tubing as it is installed in a borehole and deployed to act as an annular isolator in conjunction with expansion of the tubing. In one form, one, or preferably multiple, rings have radial and axial dimensions and shapes selected to form a fluid tight seal with a maximum borehole size after tubing expansion, and to form a seal after tubing expansion in a minimum sized borehole without exceeding maximum allowable stress. In other forms, a sleeve has a reduced radial dimension as installed on tubing for running into a borehole where its radial dimension is increased prior to or in conjunction with tubing expansion. In one form the sleeve is stretched axially as installed on the tubing and held in place by a slidable ring during tubing installation. Upon tubing expansion the ring is released and the sleeve is allowed to return to its original radial dimension. In another form the slidable ring is driven by an expansion cone to axially compress an elastomeric sleeve and increase its radial dimension. Both mechanisms may be applied to the same elastomeric sleeve. In another form, the sleeve is designed to fold upon itself or into a circumferentially corrugated shape upon axial compression, to increase its radial dimension. Pairs of such elastomeric sleeves, bands or rings may be used to isolate a section of annulus into which annular isolator forming material carried with the tubing or conveyed down hole through tubing or a work string may be placed as discussed above.
• Although the embodiments of the present invention are intended to produce annular isolators in conjunction with tubing expansion with a fixed expansion cone type tool, other expansion means may also be used to advantage. Inflatable bladders may be used for primary expansion, or for overexpanding tubing sections which carry annular isolator forming materials including elastomeric sleeves, rings or bands. Adjustable or variable diameter expansion cone tools may be used to overexpand tubing sections which carry annular isolator forming materials including elastomeric sleeves, rings or bands. Internal pressure applied through the tubing or a work string may be used to overexpand selected tubing sections. Axial compression of the selected tubing sections may be used to aid over expansion of such selected tubing sections. Finally, one of skill in the art will also recognize that some of the described embodiments will function and provide many of the same advantages even when used in combination with tubing which is not expanded and/or in a portion of the borehole which has been cased.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of a borehole in the earth with an open hole completion and a number of annular isolators according to the present invention.
• FIG. 2 is a cross-sectional illustration of expandable tubing in an open hole completion carrying elastomeric rings or bands on the outer surface of the tubing.
• FIG. 3 is a cross-sectional illustration of an elastomeric sleeve on the outer surface of expandable tubing, which has been prestretched to reduce its thickness during installation of the tubing in the borehole.
• FIG. 4 is a cross-sectional illustration of the embodiment ofFIG. 3 after the prestretched sleeve has been released by an expansion cone.
• FIG. 5 is an illustration of use of an adjustable expansion cone to expand expandable tubing and an elastomeric sleeve into an enlarged portion of an open borehole to form an annular isolator.
• FIGS. 6 and 7 are cross-sectional illustrations of an embodiment including elastomeric sleeves on the outer surface of an expandable tubing which are folded before tubing expansion to form an annular isolator in an enlarged portion of a borehole.
• FIGS. 8 and 9 are cross-sectional illustrations of latching mechanisms for holding the elastomeric sleeve ofFIGS. 6 and 7 in place during installation of tubing in a borehole.
• FIG. 10 is a cross-sectional illustration of expandable tubing carrying reactive chemicals in a matrix on its outer surface for installation in a borehole.
• FIG. 11 is a cross-sectional illustration of expandable tubing carrying reactive chemicals in a reduced diameter portion for installation in a borehole.
• FIG. 12 is a cross-sectional illustration of expandable tubing carrying a fluid within a reduced diameter portion and covered by an expandable sleeve having a pressure relief valve.
• FIG. 13 is a cross-sectional illustration of expandable tubing having a reduced diameter corrugated section carrying a fluid and covered by an expandable sleeve having a pressure release valve.
• FIG. 14 is a cross-sectional view of theFIG. 13 embodiment which illustrates corrugated expandable tubing and the location of annular isolator forming material.
• FIG. 15 is a partial cross-sectional illustration of another embodiment of the present invention having an annular isolator forming fluid carried within a recess in expandable tubing and arranged to inflate an elastomeric sleeve upon tubing expansion.
• FIG. 16 illustrates the condition of theFIG. 14 embodiment after the expandable tubing has been expanded.
• FIGS. 17, 18, and19 are cross-sectional illustrations of an expandable tubing assembly having an elastomeric sleeve which can be expanded as part of the tubing expansion process.
• FIG. 20 is a cross sectional illustration of an alternative form of the embodiment ofFIGS. 17, 18 and19.
• FIGS. 21, 22, and23 are cross-sectional illustrations of an elastomeric sleeve with an embedded spring that may be carried on an expandable tubing and released to form an annular isolator as a result of expansion of the tubing.
• FIGS. 24 and 25 are illustrations of expandable tubing having an inflatable bladder and a two part chemical system driven by a spring-loaded piston for inflating the bladder as part of expansion of the tubing.
• FIG. 26 is a partially cross-sectional view of an expandable tubular element carrying a compressed foam sleeve held in position by a grid which may be released upon expansion of the tubing.
• FIG. 27 is a cross-sectional illustration of expandable tubing carrying a sleeve which may be expanded by a chemical reaction driving a piston which is initiated by expansion of the tubing.
• FIGS. 28 and 29 are illustrations of expandable tubing carrying folded plates which may be expanded to form a basket upon expansion of the tubing.
• FIG. 30 is a cross-sectional illustration of expandable tubing having an interior chamber carrying an annular isolator forming material which may be forced into an external inflatable sleeve upon passage of an expansion cone through the expandable tubing.
• FIG. 31 is a cross-sectional illustration of expandable tubing carrying an inflatable rubber bladder on a recessed portion and an expansion string to fill the rubber bladder with fluid pumped from the surface prior to running of an expansion cone through the reduced diameter portion of the tubing.
• FIG. 32 is a cross-sectional illustration of expandable tubing carrying an elastomeric sleeve and an expansion tool used to expand the tubing into contact with the borehole using pressure fluid pumped from the surface.
• FIGS. 33 and 34 are cross-sectional illustrations of system using an axial load and interior pressure to cause expansion of expandable tubing and an external sleeve into contact with a borehole wall to form an annular isolator.
• FIG. 35 is a cross-sectional illustration of expanded tubing and an injection tool for placing an annular isolator forming material in the annulus between the expanded tubing and the borehole wall.
• FIG. 36, is a cross sectional illustration of an alternate system for preexpanding an externally carried elastomeric sleeve of the type shown in FIGS.6 to9.
• FIG. 37 is a cross sectional illustration of yet another system for preexpanding an externally carried elastomeric sleeve of the type shown in FIGS.6 to9.
• FIGS. 38, 39,40 and41 illustrate the deployment of an external sleeve having multiple sections which inflate at different internal pressure levels to form an annular isolator.
• FIG. 42 is a cross sectional illustration of an embodiment having a conduit in the annulus passing through an inflatable isolator.
• FIG. 43 is a more detailed illustration of a portion ofFIG. 42.
• FIG. 44 is an illustration of a pair of conduits located in an annulus and bypassing an inflatable isolator element.
• FIG. 45 is an illustration of a circumferentially corrugated elastomeric sleeve which may be used to form an annular isolator.
DETAILED DESCRIPTION OF THE INVENTION
• The term “annular isolator” as used herein means a material or mechanism or a combination of materials and mechanisms which blocks or prevents flow of fluids from one side of the isolator to the other in the annulus between a tubular member in a well and a borehole wall or casing. An annular isolator acts as a pressure bearing seal between two portions of the annulus. Since annular isolators must block flow in an annular space, they may have a ring like or tubular shape having an inner diameter in fluid tight contact with the outer surface of a tubular member and having an outer diameter in fluid tight contact with the inner wall of a borehole or casing. An annular isolator could be formed by tubing itself if it could be expanded into intimate contact with a borehole wall to eliminate the annulus. An isolator may extend for a substantial length along a borehole. In some cases, as described below, a conduit may be provided in the annulus passing through or bypassing an annular isolator to allow controlled flow of certain materials, e.g. hydraulic fluid, up or down hole.
• The term “perforated” as used herein, e.g. perforated tubing or perforated liner, means that the member has holes or openings through it. The holes can have any shape, e.g. round, rectangular, slotted, etc. The term is not intended to limit the manner in which the holes are made, i.e. it does not require that they be made by perforating, or the arrangement of the holes.
• With reference now toFIG. 1, there is provided an example of a producing oil well in which an annular isolator according to the present invention is useful. InFIG. 1, aborehole10 has been drilled from the surface of the earth12. An upper portion of theborehole10 has been lined withcasing14 which has been sealed to theborehole10 bycement16. Below the cased portion ofborehole10 is anopen hole portion18 which extends downward and then laterally through various earth formations. For example, theborehole18 may pass through awater bearing zone20, ashale layer21, anoil bearing zone22, anonproductive zone23 and into anotheroil bearing zone24. As illustrated inFIG. 1, theopen hole18 has been slanted so that it runs through the zones20-24 at various angles and may run essentially horizontally through oil-bearingzone24. Slant hole or horizontal drilling technology allows such wells to be drilled for thousands of feet away horizontally from the surface location of a well and allows a well to be guided to stay within a single zone if desired. Wells following an oil bearing zone will seldom be exactly horizontal, since oil bearing zones are normally not horizontal.
• Tubing26 has been placed to run from the lower end of casing14 down through the open hole portion of the well18. At its upper end, thetubing26 is sealed to thecasing14 by anannular isolator28. Anotherannular isolator29 seals the annulus betweentubing26 and the wall ofborehole18 within theshale zone21. It can be seen thatisolators28 and29 prevent annular flow of fluid from thewater zone20 and thereby prevent production of water fromzone20. Withinoil zone22,tubing26 has a perforatedsection30.Section30 may be a perforated liner and may typically carry sand screens or filters about its outer circumference. A pair ofannular isolators31 prevents annular flow to, from or through thenonproductive zone23. Theisolators31 may be a single isolator extending completely through thezone23 if desired. The combination ofisolator29 andisolators31 allow production fromoil zone22 into theperforated tubing section30 to be selectively controlled and prevents the produced fluids from flowing through the annulus to other parts of theborehole18. Withinoil zone24,tubing26 is illustrated as having twoperforated sections32 and33.Sections32 and33 may be perforated and may typically carry sand screens or filters about their outer circumference.Annular isolators36 and38 are provided to seal the annulus between thetubing26 and the wall ofopen borehole18. Theisolators31,36 and38 allow separate control of flow of oil into theperforated sections32 and33 and prevent annular flow of produced fluids to other portions ofborehole18. The horizontal section ofopen hole18 may continue for thousands of feet through theoil bearing zone24. Thetubing26 may likewise extend for thousands of feet withinzone24 and may include numerous perforated sections which may be divided by numerous annular isolators, such asisolators36 and38, to divide thezone24 into multiple areas for controlled production.
• It is becoming more common for thetubing26 to comprise expandable tubular sections. Both the solid sections of thetubing26 and theperforated sections32 and33 are now often expandable. The use of expandable tubing provides numerous advantages. The tubing is of reduced diameter during installation which facilitates installation in offset, slanted or horizontal boreholes. Upon expansion, solid, or perforated tubing and screens provide support for uncased borehole walls while screening and filtering out sand and other produced solid materials which can damage tubing. After expansion, the internal diameter of the tubing is increased improving the flow of fluids through the tubing. Since there are limits to whichexpandable tubing26 may be expanded and the borehole walls are irregular and may actually change shape during production, annular flow cannot be prevented merely by use ofexpandable tubing26, including expandable perforated sections andscreens32 and33. To achieve the desirable flow control, annular barriers orisolators36 and38 are needed. Typical annular isolators such as inflatable packers have not been found compatible with the type of production installation illustrated inFIG. 1 for various reasons including the fact that the structural members required to mount and operate such packers are not expandable along with thetubing string26.
• With reference toFIG. 2, an improved system and method of installation of annular isolators such aselements36 and38 shown inFIG. 1 is provided. InFIG. 2 is illustrated anexpandable tubing42 positioned within anopen borehole40. On the right side ofFIG. 2, the tubing is shown in its unexpanded state and carries on it outer surface a ring or band ofelastomeric material44, for example rubber. In this embodiment, thering44 has fairly short axial dimensions, i.e. its length along the axial length of thetubing42, but has a relatively long radial dimension, i.e. the distance it extends from the tubing in the radial direction towards theborehole wall40. The rings are preferably tapered radially as illustrated to have a longer axial dimension where bonded to the outer surface of the tubing and shorter axial dimension on the end which first contacts the borehole wall. As run into the borehole, thetubing42 carriesring44 and asimilar ring46 which together may form a single annular isolator such asisolator36 inFIG. 1. Therings44 and46 may be installed on thetubing42 by being cast in a mold positioned around thetubing42. The tubing may also be covered by a continuous sleeve of elastomer betweenrings44 and46 which may be formed in the same casting and curing process. Also shown inFIG. 2 is anexpansion cone48 which has been driven into theexpandable tubing42 from the left side as indicated by arrow50. As the cone passes through the tubing from left to right, the tubing is expanded to a larger diameter as indicated at52. As the expansion cone passed through thering46, thering46 was forced into contact with thewall40. Expansion of thetubing52 reduced the radial dimension and increased the axial dimension of thering46, since the total volume must remain constant. Stated otherwise, thering46 was partially displaced axially in the annulus between the expandedtubing52 andborehole40. When theexpansion cone48 passes throughring44, it will likewise be expanded into contact with theborehole wall40. Eachannular isolator36,38 ofFIG. 1 may comprise two or more such rubber rings44 and46 carried on expandable tubing as illustrated inFIG. 2.
• Also illustrated inFIG. 2 is aconduit45 extending along the outer surface oftubing42 and passing through therings44 and46. It is often desirable in well completions to provide control, signal, power, etc. lines from the surface to down hole equipment. The lines may be copper or other conductive wires for conducting electrical power down hole or for sending control signals down hole and signals from pressure, temperature, etc. sensors up hole. Fiber optic lines may also be used for signal transmissions up or down hole. The lines may be hydraulic lines for providing hydraulic power to down hole valves, motors, etc. Hydraulic lines may also be used to provide control signals to down hole equipment. Theconduit45 may be any other type of line, e.g. a chemical injection line, used in a down hole environment. It is usually preferred to route these lines on the outside of the tubing rather than in the production flow path up the center of the tubing. The lines can be routed through the rubber rings44 and46 as illustrated while maintaining isolation of the annulus with therings44,46.
• TheFIG. 2 embodiment solves several problems of prior art devices. Such devices have included relatively thin rubber sleeves on the outside of expandable screens, which sleeves extend for substantial distances axially along the tubing. In enlarged portions of open boreholes such sleeves typically do not make contact with the borehole and thus do not form an effective annular isolator. In well consolidated formations, such prior art sleeves may contact the borehole wall before the expandable tubing is fully expanded creating excessive forces in the expansion process. Due to their axial length, the forces required to extrude or flow such sleeves axially in the annulus cannot be generated by an expansion tool and, if they could, would damage the borehole or the tubing.
• In theFIG. 2 embodiment, the elastomeric rings44 and46 have radial and axial dimensions selected to achieve several requirements. One requirement is for the rings to contact a borehole wall with sufficient stress to conform to the borehole wall and act as an effective annular isolator. The radial dimension or height of the ring therefore is selected to be greater than the width of the annulus between expanded tubing and the wall of the largest expected borehole. The ring will therefore be compressed radially and will expand axially in the annulus as a result of tubing expansion. By proper selection of elastomeric material and the axial length of the ring relative to the radial dimension, a minimum stress level can be generated to provide a seal with the borehole wall.
• Another requirement is to avoid damage which may result from excessive stress in therings44,46. Excessive stresses may be encountered when tubing is expanded in a borehole having a nominal or less than nominal diameter. Such excessive stress may damage the borehole wall, i.e. the formation, by overstressing and crushing the borehole wall. In some cases, some compression of the borehole wall is acceptable or even desirable. Excessive stress can also cause collapse or compression of the tubing after an expansion tool has passed through the rings. That is, the stress in the elastomeric rings may be sufficient to reduce the tubing diameter after an expansion tool has passed through the tubing or been removed. Excessive stress may damage or stop movement of an expansion tool itself. That is, the stress may require forces greater than those available from a given expansion tool.
• When expanding tubing in minimum diameter boreholes, the elastomeric rings must be capable of axial expansion at internal stresses which are below levels which would cause damage to the borehole wall, tubing or expansion tool. The radial dimension of the rings is selected as discussed above. Based on any given radial dimension and the characteristics of the selected elastomer, the axial dimension of the ring is selected to allow expansion of the tubing in the smallest expected borehole without generating excessive pressures. The smaller the axial dimension, the less force is required to compress the elastomeric ring radially from its original radial dimension to the thickness of the annulus between the expanded tubing and the smallest expected borehole.
• The tapered shape of therings44,46 is one way in which the requirements can be achieved. As is apparent from the above discussion, the amount of force required to radially compress therings44,46 is related to the axial length of the rings. With a tapered shape as shown inFIG. 2 (or the tapers shown inFIGS. 10 and 11), the ring does not have a single axial dimension, but instead has a range of axial dimensions. The shortest axial dimension is on the outer circumference which will first contact a borehole wall. The force required to cause radial compression and axial expansion is therefore smallest at the outer circumference. That is, the deformation of the ring during tubing expansion effectively begins with the portion which first contacts the borehole wall. This helps insure conformance of the ring with the borehole wall surface. The same effect can be achieved with other cross sectional shapes of therings44,46 such as hemispherical or parabolic which would also provide a greater axial dimension adjacent the tubing and shorter axial dimension at the outer circumference of the rings.
• It is preferred that an annular isolator according to theFIG. 2 embodiment include two or more of the illustrated rings44,46. It is also preferred that the axial dimensions of the rings be selected to allow annular expansion or extrusion of the elastomer as the ring is compressed radially. This assumes, of course, that there is available annular space into which the elastomer may expand without restriction. If adjacent rings are spaced too closely, they could contact each other as they expand axially in the annulus. Upon making such contact, the forces required for further radial compression may increase substantially. It is therefore preferred thatadjacent rings44,46 be spaced apart sufficiently to allow unrestricted annular expansion at least in the minimum sized borehole. Since elastomers such as rubber are essentially incompressible, sufficient annular volume should be available to accommodate the volume of elastomeric material which will be displaced axially by the greatest radial compression of the rings. While the illustrated embodiment shows an absence of material between the two rings, as discussed above, there may also be a radially shorter linking sleeve section between the two rings. Even in such a case, the design could still be implemented to provide available volume (space) above the sleeve section between the two rings to accommodate the desired expansion.
• With reference theFIGS. 3 and 4, another embodiment of an external annular isolator is illustrated. InFIG. 3 is shown a portion of an unexpanded expandabletubular member54. Carried on the outside ofexpandable member54 is a pre-stretchedelastomeric sleeve56.Sleeve56 has been stretched axially to increase its axial dimension and reduce its radial dimension from the dimensions it has when free of such external forces. One end ofsleeve56 is attached to aring58 which may be permanently attached to the outer surface oftubular member54 by welding or may be releasably attached by bonding or crimping as discussed below. On the other end ofelastomeric sleeve56 is attached a slidingring60 which is captured in arecess62 in thetubing54. InFIG. 4, theelastomeric sleeve56 is illustrated in its relaxed or unstretched condition free of the stretching force. InFIG. 4, theexpansion cone64 has been forced into theexpandable member54 from the left side and has moved past the lockingrecess62. As it did so, thetubing54 includingrecess62 was expanded to final expanded diameter. When this happened, the slidingmember60 was released and theelastomeric sleeve56 was allowed to return to its unstretched dimensions.
• As noted above, it is desirable for expandable tubing to reduce the annulus between the tubing string and the borehole wall as much as possible. The tubing may be expanded only a limited amount without rupturing. It is therefore desirable for the tubing to have the largest possible diameter in its unexpanded condition as it is run into the borehole. That is, the larger the tubing is before expansion, the larger it can be after expansion. Elements carried on the outer surface of tubing as it is run in to a borehole increase the outer diameter of the string. The total outer diameter must be sized to allow the string to be run into the borehole. The total diameter is the sum of the diameter of the actual tubing plus the thickness or radial dimension of any external elements. Thus external elements effectively reduce the allowable diameter of the actual expandable tubing elements.
• In the embodiment ofFIGS. 3 and 4, the total overall diameter ofexpandable tubing54 as it is run into the borehole is reduced by prestretchingelastomeric sleeve56 into the shape shown inFIG. 3. The reduction in radial dimension ofsleeve56 allows thetubing54 to have a larger unexpanded diameter. As the tubing is expanded as illustrated inFIG. 4, theelastomeric sleeve56 is allowed to return to its original shape in which it extends further radially from thetubing54. As a result, whenexpansion cone64 passes beneathelastomeric sleeve56, it will form an annular isolator in a larger borehole or an irregular borehole. The relaxed shape ofsleeve56 is selected so that for the largest expected diameter of borehole, the sleeve will contact the borehole wall upon tubing expansion and be compressed radially with sufficient internal stress to form a good seal with the borehole wall. Upon radial compression, thesleeve56 will expand or extrude to some extent axially along the annulus since the volume of the elastomer remains constant.
• It is possible that the annular isolator ofFIGS. 3 and 4 is positioned in a competent borehole which is at the nominal drilled size or is even undersized due to swelling of the borehole wall on contact with drilling fluid. In such cases, the relaxed thickness ofsleeve56 may be sufficient to contact theborehole wall57 before expansion oftubing54. As thecone64 passes under thesleeve56, it would then need to expand or extrude further axially to avoid excessive forces. This pressure relief can occur in either of two ways. The slidingring60 can be adapted so that, after expansion, it can slide on the expandedtubing54 at a preselected force level. Alternatively thering58 can be attached to thetubing54 with a crimp or similar bond which releases and allows limited movement at axial force above a preselected level. In either case, the maximum force exerted by the expansion oftubing54 under thesleeve56 can be limited while maintaining a significant stress on thesleeve56 to achieve a seal with a borehole wall. Ifring58 is used as a pressure relief device, it is desirable to provide a locking mechanism to prevent further sliding after the expandingtool64 has passed through thering58. The locking device can be one or moreslip type teeth59 on thering58 which will bite into thetubing54 when it expands under thering58. Other mechanisms may be used to allow limited pressure relief while retaining sufficient stress in thecompressed sleeve56 to maintain a good seal to a borehole.
• InFIG. 5, there is illustrated a partially expandedexpandable tubing section66.Section66 carries fixedelastomeric sleeves68 and70 on its outer circumference. In this illustration, theborehole wall72 is shown with anenlarged portion74 at the location ofelastomeric sleeve70. In this embodiment, an adjustable or variablediameter expanding cone76 is employed to expand thetubing66. As thetubing66 is expanded in the area of theenlarged area74, the diameter of thecone76 has been increased tooverexpand tubing66 causingsleeve70 to make a firm contact with borehole wall inregion74. Inarea75 ofborehole wall72 which has not been enlarged,sleeve68 will make contact with normal expansion oftubing66. Thevariable expansion cone76 may be used in conjunction with a fixed expansion cone such ascone48 ofFIG. 2 orcone64 ofFIG. 4. Both cones can be carried on one expansion tool string, or the adjustable cone can be carried down hole with the tubing as it is installed and picked up by the expansion tool when it reaches the end of the tubing string. After expansion of the tubing, screens, etc., by a fixed cone, theadjustable cone76 may be used to further expand the sections withexternal sleeves70 to ensure making a seal with the borehole. This can be done on a single trip into the borehole. For example, the fixed cone can expand the entire tubing string as the tool is run down the borehole and the adjustable cone can be deployed at desired locations as the tool is run back up hole.
• FIGS. 6, 7,8 and9 illustrate another embodiment having an external elastomeric sleeve which has a variable radial dimension which is increased before tubing is expanded. InFIGS. 6 and 7, anelastomeric sleeve80 is illustrated in its position as installed for running tubing into a borehole. Thesleeve80 is connected at one end to a fixedring82 on thetubing78. Thering82 holds thesleeve80 in place. A slidingring84 is connected to the other end ofsleeve80.Elastomeric sleeve80 is notched or grooved at86 to generate hinge or flexing sections.
• Asecond sleeve88 is illustrated in two stages of deployment on the left sides ofFIGS. 6 and 7.Sleeve88 was essentially identical tosleeve80 whentubing78 was run into a borehole. InFIG. 6, anexpansion tool90 has moved into the left side oftubing78 and expanded a portion oftubing78 up to a slidingring92 connected to the left end ofsleeve88. As the expanding portion oftubing78contacts ring92, the ring is pushed to the right and folds thesleeve88 into the accordion shape as illustrated. In the folded condition, thesleeve88, has an increased radial dimension, i.e. it extends substantially farther from the outer surface oftubing78 than it did as installed for running in. Thesleeves80,88 may fold into shapes other than that shown inFIGS. 6 and 7. In alternative embodiments, thesleeves80 and88 may be unnotched or otherwise configured for folding and may simply be compressed by the slidingrings84,92 into a shape like that shown inFIG. 4. InFIG. 7, theexpansion tool90 has passed completely under thesleeve88 and expanded thetubing78 and expandedsleeve88 so that thesleeve88 has contacted a borehole wall at94. The slidingring92 moved to the right until thesleeve88 was completely folded and stopped further movement ofring92. At that point thetool90 passed under thering92, expanding it along with thetubing78.
• InFIGS. 8 and 9, means for holding sliding rings, such asrings84 and92 inFIGS. 6 and 7, in place during installation of the tubing are illustrated. InFIGS. 8 and 9, anelastomeric sleeve96 and fixedring98 may be the same asparts80 and82 shown inFIGS. 6 and 7. InFIGS. 8 and 9, expandable tubing100 is provided with arecess102 for holding a sliding ring in place. InFIG. 8, a slidingring104 has amatching recess106 near its center which extends intorecess102 to lock the sliding ring in place. InFIG. 9, a slidingring108 has anedge110 shaped to fit withinrecess102. In both theFIG. 8 andFIG. 9 embodiments, therecesses102 will be removed or flattened as an expansion cone is forced through expandable tubing100. When this occurs, the slidingrings104 and108 will no longer be locked into place and will be free to slide along the expandable tubing100 as it is expanded. After tubing expansion, theelastomeric sleeve96 inFIGS. 8 and 9 may take the form ofsleeve88 shown inFIG. 7.
• As noted above with reference toFIGS. 3 and 4, it is possible in a small borehole that expansion ofsleeve88 as shown inFIG. 7 would result in excessive pressure or force on the expansion tool. Pressure relief can be provided in the same manner as discussed above. That is, the slidingring92 may be adapted to slide back to the left in response to excessive pressure on thesleeve88. Or thering90 can be connected totubing78 with a crimp, like the arrangements shown inFIGS. 8 and 9, so that it releases and slides to the right if sufficient force is applied.
• With reference now toFIG. 10, an alternate embodiment in which expanding chemical materials are used to form an annular isolator is illustrated. InFIG. 10,expandable tubing112 is essentially the same as expandable tubing shown in the previous Figures. In this embodiment, twoelastomeric rings114 and116, which may be essentially the same asrings44 and46 shown inFIG. 2, are carried on an outer surface of thetubing112.Tubing112 may have a fluid tight wall between therings114 and116 and may be perforated on the ends of the portion which is illustrated. Betweenelastomeric rings114 and116, there is provided a cylindrical coating orsleeve118 of various chemical materials carried on the outer wall oftubing112. In this embodiment, thelayer118 includes solid particles of magnesium oxide andmonopotassium phosphate120 encapsulated in an essentiallyinert binder122, for example dried clay. The chemicals magnesium oxide and monopotassium phosphate will react in the presence of water and liquefy. The liquid will then go to a gel phase and eventually crystallize into a solid ceramic material magnesium potassium phosphate hexahydrate. This material is generally known as an acid-base cement and is sometimes referred to as a chemically bonded ceramic. It normally hardens in about twenty minutes and binds well to a variety of substrates. Other acid-base cement systems may be used if desired. Some require up to twenty-two waters of hydration and may be useful where larger void spaces need to be filled. While this embodiment uses a material like clay as the encapsulatingmaterial122, any other material or packaging arrangement which separates the individual chemical particles during installation oftubing112 in a well bore and prevents liquids in the borehole from contacting chemical materials may be used. As disclosed below, the individual chemical components may be encapsulated in microcapsules, tubes, bags, etc. which separate and protect them during installation of tubing in a bore hole.
• Upon driving an expansion cone through thetubing112 as illustrated inFIG. 2, the encapsulatingmaterial122 is broken or crushed allowing thechemical materials120 to mix with water in the borehole annulus and react to form the solid material as discussed above. In thisFIG. 10 embodiment, the elastomeric rings114 and116 are used primarily to hold thechemical reactants120 in position until the chemical reaction has been completed. As the reaction occurs, the volume of chemical materials expands by the reaction with and incorporation of water and the final annular isolator is formed by the reacted chemicals. Thus, the elastomeric rings114 and116 are optional, but are preferred to ensure proper placement of the chemicals as they react. It is desirable that therings114 and116 be designed to allow release of material in the event the chemical reaction results in excessive pressure which might damage thetubing112. In many cases it may be desirable for one or both of therings114,116 to be sized to not form a total seal with the borehole. This will allow additional water and other annular fluids to flow into the area to provide waters of hydration. With such a loose fit, therings114 and116 will diminish outflow of more viscous materials such as the gel at lower pressures, while allowing some flow of more fluid materials or of the gel at excessive pressures. If desired, the chemicals may be encapsulated in a heat sensitive material and released by running a heater into thetubing112 to the desired location.
• Also illustrated inFIG. 10 is aconduit115 passing through therings114,116 and thechemical coating118. Thisconduit115 is provided for power, control, communication signals, etc. likeconduit45 discussed above with reference toFIG. 2. In this embodiment, theconduit115 will be imbedded in the acid base cement after it sets to form an annular isolator. Many of the advantages of this described embodiment are achieved regardless of the presence or absence of theconduit115.
• FIG. 11 illustrates another embodiment using various chemical materials for forming an annular isolator. Anexpandable tubing section124 preferably carries a pair ofelastomeric rings126 and128. Between the locations ofrings126 and128, thetubing124 has an annular recessedarea130. Within therecess130 is carried a swellable polymer132 such as cross-linked polyacrylamide in a dry condition. Arupturable sleeve134 is carried on the outer wall oftubing124 extending across the recessedsection130. The space betweensleeve134 and recessedsection130 defines a compartment for carrying a material for forming an annular isolator, i.e. the swellable polymer132. Thesleeve134 protects the swellable polymer132 from fluids during installation of thetubing124 into a borehole. The material132 may be in the form of powder or fine or small particles which are held in place by thesleeve134. The material132 may also be made in solid blocks or sheets which may fracture on expansion. It may also be formed into porous or spongy sheets. If solid or spongy sheet form is used, thesleeve134 may not be needed or may simply be a coating or film adhered to the outer surface of the material132. When an expansion cone is forced through thetubing124, the reduceddiameter portion130 is expanded along with the rest oftubing124 to the final designed expanded diameter. Rubber rings126 and128 will be expanded to restrict or stop annular flow. Theprotective sheath134 is designed to split or shatter instead of expanding thus exposing the polymer132 to fluids in the wellbore. Polymer132 will absorb large quantities of water and swell to several times its initial volume. The material132 at this point will have been forced outside the final diameter of thetubing124 and thereby into contact with the borehole wall. The combination of the swellable polymer and theelastomeric seals126 and128 forms an annular isolator. The annular isolator thus formed remains flexible and will conform to uneven borehole shapes and sizes and will continue to conform if the shape or size of the borehole changes.
• Various other solid, liquid or viscous materials can be used as the chemical materials132 in theFIG. 11 embodiment. The swellable polymer may be formed into sheets or solid shapes which may be carried on thetubing124. The acid-base cement materials used in theFIG. 10 embodiment could be carried within therecess130 and protected by thesheath134 during installation of thetubing124. As discussed with reference toFIG. 10, the elastomeric rings126 and128 are optional, but preferred to hold materials in place while reactions occur and are preferably designed to limit the amount of pressure that can be generated by the swelling materials.
• With reference now toFIG. 12, there is illustrated another embodiment of the present invention in which a fluid may be used to inflate a sleeve. InFIG. 12,expandable tubing136 is formed with a reduceddiameter portion138 providing a recess in which a flowable annularisolator forming material140 may be stored. An outer inflatable metal sheath orsleeve142 forms a fluid tight chamber or compartment with the reduceddiameter section138. Thissheath142 as installed has an outer diameter greater than theexpandable member136 to increase the amount ofmaterial140 which may be carried down hole with thetubing136. Theouter sheath142 is bonded by welding or otherwise to thetubing136 at uphole end144. At its downhole end146, thesheath142 is bonded to thetubing136 with anelastomeric seal148. Aretainer sleeve150 has one end welded to thetubing136 and an opposite end extending overend146 of theouter sleeve142. Theretainer sleeve150 preferably includes at least onevent hole152 near its center. Aportion143 ofouter sleeve142 is predisposed to expand at a lower pressure than the remaining portion ofsleeve142. Theportion143 may be made of a different material or may be treated to expand at lower pressure. For example, theportion143 may be corrugated and annealed before assembly into the form shown inFIG. 11.Portion143 is preferably adjacent theend146 ofsleeve142 which would be expanded last by an expansion tool. The metallicouter sleeve142 may be covered by an elastomeric sleeve orlayer154 on its outer surface. Anelastomeric sleeve154 is preferred onportion143 if it is corrugated to help form a seal with a borehole wall in case the corrugations are not completely removed during the expansion process. Theelastomeric sleeve154 would also be preferred on any portion of thesleeve142 which is perforated.
• Theinflatable sleeve142 and other inflatable sleeves discussed below are referred to as “metal” sleeves or sheaths primarily to distinguish from elastomeric materials. They may be formed of many metallic like substances such as ductile iron, stainless steel or other alloys, or a composite including a polymer matrix composite or metal matrix composite. They may be perforated or heat-treated, e.g. annealed, to reduce the force needed for inflation.
• In operation, the embodiment ofFIG. 12 is run into a wellbore in the condition as illustrated inFIG. 12. Once properly positioned, an expander cone is forced through thetubing136 from left to right as illustrated inFIG. 2. When the cone reaches the reduceddiameter section138 and begins expanding it to the same final diameter astubing136, the pressure ofmaterial140 is increased. As pressure increases, theouter sleeve142 is inflated outwardly towards a borehole wall. Inflation begins with theportion143 which inflates at a first pressure level. When theportion143 contacts a borehole wall, the pressure ofmaterial140 increases until a second pressure level is reached at which the rest ofouter sleeve142 begins to inflate. If proper dimensions have been selected, the inflatableouter sleeve142 andelastomeric layer154 will be pressed into conforming contact with the borehole wall. To ensure that such contact is made, it is desirable to have an excess ofmaterial140 available. If there is excess material and theouter sleeve142 makes firm contact with an outer borehole wall over its whole length, the expansion process will raise the pressure ofmaterial140 to a third level at which thepolymeric seal148 opens and releases excess material. The excess material may then flow through thevent152 into the annular space betweentubing136 and a borehole wall. When the expander cone has moved to theend146 of theouter sleeve142,tubing136 and theouter sleeve142 will be expanded against the overlapping portion of theretainer sleeve150. As these parts are all expanded together, a seal is reformed preventing further leakage ofmaterial140 from the space between thetubing136 and theouter sleeve142. Thematerial140 may be any of the reactive or swellable materials disclosed herein so that the extra material vented at152 may react, e.g. with ambient fluids, to form an additional annular isolator between thetubing136 and the borehole wall.
• In theFIG. 12 embodiment, theouter sleeve142 is shown to have an expanded initial diameter to allowmore material140 to be carried into the borehole. As discussed above, this arrangement results in a smaller maximum unexpanded diameter oftubing136. It would be possible to form a fluid compartment or reservoir with only theouter sleeve142, that is without the reduceddiameter tubing section138. However, to achieve the same volume of stored fluid, thesleeve142 would have to extend farther fromtubing136 and the maximum unexpanded diameter oftubing136 would be further reduced.
• FIG. 13 illustrates an alternative embodiment which allows a greater unexpanded diameter of anexpandable tubing156. In this embodiment, anouter sleeve158 has a cylindrical shape and has essentially the same outer diameter as thetubing156. Otherwise, theouter sleeve158 is sealed to thetubing156 in the same manner as theouter sleeve142 ofFIG. 11. Likewise, this embodiment includes apressure relief arrangement157 which may be identical to the one used in theFIG. 12 embodiment. Thesleeve158 preferably has aportion159 predisposed to expand at a lower pressure than the remaining portion ofsleeve158, like theportion143 ofouter sleeve142 ofFIG. 12.Sleeve158 may carry an outer elastomeric sleeve likesleeve154 inFIG. 12.
• In order to provide storage space for a larger volume of annular isolator forming material in theFIG. 13 embodiment, a reduceddiameter portion160 oftubing156 is corrugated as illustrated inFIG. 14. It is preferred that theportion160 be formed from tubing having a larger unexpanded diameter than the unexpanded diameter oftubing156. During corrugation of theportion160, the tubing wall may be stretched to have a larger total circumference after corrugation and then annealed to relieve stress. Each of these arrangements helps reduce total stresses in thesection160 which result from unfolding the corrugations and expanding to final diameter. As can be seen fromFIG. 14, the crimping or corrugation of thesection160 oftubing156 produces relativelylarge spaces162 for storage of expansion fluid. When an expansion cone is run through the tubing in the embodiment ofFIG. 13, the corrugations are unfolded driving the materials inspaces162 to inflate theouter sleeve158 in the same manner as described with respect toFIG. 12. Except for the unfolding of thecorrugated section160, the embodiment ofFIG. 13 operates in the same way as theFIG. 12 embodiment. That is, as an expansion tool moves throughtubing156 from left to right,material162 reaches a first pressure level at whichsleeve section159 expands until it contacts a borehole wall. Then the material reaches a second pressure level at which the rest ofsleeve158 expands. If thewhole sleeve158 contacts the borehole wall, a third pressure level is reached at which therelief valve arrangement157 vents excess material into the annulus.
• The pressure relief arrangements shown inFIGS. 12 and 13, and in many of the following embodiments, are preferred in expandable tubing systems which use a fixed diameter cone for expansion. It is often desirable that the inner diameter of an expandable tubing string be the same throughout its entire length after expansion. Use of a fixed diameter expansion tool provides such a constant internal diameter. The pressure relief mechanism provides several advantages in such systems. It is desirable that a large enough quantity of expansion material be carried down hole with the expandable tubing to ensure formation of a good annular isolator in an oversized, e.g. washed out, and irregularly shaped portion of the borehole. If the borehole is of nominal size or undersized, there will then be more fluid than is needed to form the annular isolator. If there were no pressure relief mechanism, excessive pressure could occur in the material during expansion and the expansion tool could experience excessive forces. The result could be rupturing of the tubing or stoppage or breaking of the expansion tool. The pressure relief mechanisms release the excess material into the annulus to avoid excess pressures and forces, and, with use of proper materials, act as additional annular isolators.
• FIGS. 15 and 16 illustrate another embodiment of the present invention in which a material carried with expandable tubing as installed in a borehole is used to inflate an annular isolator. InFIG. 15, anexpandable tubular member164 includes a reduceddiameter section166 providing a compartment for storage of an isolator forming material, preferably afluid168. The fluid168 is held in place by anelastomeric sleeve170 which completely covers the fluid168 and extends a substantial additional distance along the outer surface of theexpandable tubing164. A first section of perforatedmetallic shroud172 is connected at afirst end174 to theexpandable tubing164. Theshroud172 extends around theelastomeric sleeve170 for a distance at least equal to the length of the reduceddiameter section166 of thetubing164. A second section ofshroud176 has oneend178 connected to thetubular member164.Shroud176 covers and holds in place one end of theelastomeric sleeve170. Betweenshroud section172 and176, a portion of theelastomeric sleeve170 is exposed. Theshroud section176 and aportion180, adjacent the exposed portion ofsleeve170, ofshroud172 are highly perforated and therefore designed to expand relatively easily. The remainingportion182 ofshroud172 has only minimal slotting (or in some embodiments no slotting) and requires greater pressure to expand. If desired, bothshroud sections172 and176 may be covered by a second elastomeric sleeve to improve sealing between a borehole wall and the shrouds after they are expanded.
• FIG. 16 illustrates the condition of this embodiment after an expander cone has been driven through theexpandable tubing164 from left to right inFIGS. 15 and 16. As the forcing cone moves through thetubing164, the fluid168 is first forced to flow under the exposed portion of theelastomeric sleeve170. As illustrated inFIG. 16, it will expand until it contacts and conforms to aborehole wall184. In this embodiment, it is preferred that the reduceddiameter section166 of thetubing164 be considerably longer than the exposed portion of therubber sleeve170. By a proper selection of the ratio of these lengths,sufficient material168 is available to provide a very large expansion of therubber sleeve170. As theelastomeric sleeve170 expands into contact with the borehole wall, the pressure offluid168 increases and the highlyperforated shroud portions176 and180 will expand also. If additional fluid is available after expansion of highlyperforated shroud portions176 and180 into contact with the borehole wall, the fluid pressure will rise sufficiently to cause expansion of the minimally perforatedportion182 of theshroud172. The slotting ofportion182 therefore provides a pressure relief or limiting function. It is also desirable to include a relief mechanism as shown inFIGS. 12 and 13 to provide an additional pressure limiting mechanism, in case the borehole is of nominal size or undersized.
• With reference now toFIGS. 17, 18, and19, there is shown an annular isolator system which provides pre-compression of an external elastomeric sleeve before expansion of the tubing on which the sleeve is carried. InFIG. 17,expandable tubing190 is shown having been partially expanded by anexpansion tool192 carried on apilot expansion mandrel194. InFIG. 17, the expandedportion196 may carry an external screen expanded into contact with aborehole wall198. To the right of this expanded portion is provided a threaded joint betweenexpandable tubing sections200 and202. Anelastomeric sleeve204 is carried on the outer diameter ofportion200. The threadedportion202 is connected to a reduceddiameter section206 of the expandable tubing into which aportion208 of theexpansion mandrel194 has been pushed to form an interference fit. Themandrel portion208 is preferably splined on its outer surface to form a tight grip with reduceddiameter section206. A rotatingbearing210 is provided between theelastomeric sleeve204 and thelower tubing section202.
• After thetubing string190 has been expanded to the point shown inFIG. 17, theexpansion mandrel194 is rotated so that itssplined end208 causes rotation oftubing section202 relative tosection200. As a result of the threaded connection, theelastomeric member204 is compressed axially so that its radial dimension is increased as illustrated inFIG. 18.
• Once theelastomeric sleeve204 has been expanded as illustrated inFIG. 18, theexpansion cone192 may be forced through thetubing string190 past thetubing sections200 and202 expanding all the sections to final diameter and drivingelastomeric sleeve204 into engagement withborehole wall198 as shown inFIG. 19. As thetubing string190 is expanded, the threaded connection betweensections200 and202 are firmly bonded together to prevent further rotation.
• With reference toFIG. 20, an alternative form of the embodiment ofFIGS. 17, 18 and19 is illustrated. In this embodiment the same expansion tool includingexpansion cone192,mandrel194 andsplined end208 may be used. Twoexpandable tubing sections209 and210 are connected by aninternal sleeve211. Thesleeve211 has external threads on each end which mate with internal threads onsections209 and210. The sleeve has anexternal flange212 and aninternal flange213 near its center. Anelastomeric sleeve214 is carried onsleeve211 between theexternal flange212 and thetubing section209. Theinternal flange213 is sized to mate with thesplined end208 ofmandrel194. ThisFIG. 20 system operates in essentially the same way as the system shown inFIGS. 17, 18 and19. As theexpansion cone192 is passing through and expanding thetubing section209, thesplined end208 engages theinternal flange213. Expansion cone downward movement is stopped andmandrel194 is rotated to turn thesleeve211 relative to bothtubing sections209 and210. Assleeve211 turns, it moves theexternal flange212 away fromtubing section210 and towardssection209 axially compressing theelastomeric sleeve214 between theflange212 and the end oftubing section209. Thesleeve214 will increase in radial dimension as illustrated inFIG. 18. Then the expansion cone may be driven through the rest oftubing209, thesleeve211 and thetubing210 to expand the tubing and force theelastomeric sleeve214 outward toward a borehole wall to close off the annulus as illustrated inFIG. 19.
• With reference now toFIGS. 21, 22 and23, there is illustrated an embodiment of the present invention in which a coil spring is used to expand an external elastomeric sleeve to form an annular isolator. InFIG. 21, anelastomeric sleeve220 is illustrated in its relaxed or natural shape as it would be originally manufacturedsleeve220 is made up of two parts. It includes a barrel shapedelastomeric sleeve222. That is, thesleeve222 has a diameter at each end corresponding to the outer diameter of an unexpanded tubular member and a larger diameter in its center. Embedded within theelastomeric sleeve222 is acoil spring224 having generally the same shape in its relaxed condition. InFIG. 22, thesleeve220 is shown as installed on a section of unexpandedexpandable tubing226 for running into a borehole. Themember220 has been stretched lengthwise causing it to conform to the outer diameter of thetubing226. Thesleeve220 may be held onto thetubing226 by a fixedring228 on its down hole end and a slidingring230 on its up hole end. Therings228 and230 may be essentially the same as therings58 and60 illustrated inFIG. 3. Slidingring230 would be releasably latched into a recess formed on the outer surface ofexpandable tubing226 to keep thesleeve220 in its reduced diameter shape for running into the tubing in the same manner as shown inFIG. 3.
• FIG. 23 illustrates the shape and orientation of theelastomeric sleeve220 after thetubing226 has been placed in anopen borehole232 and an expansion cone has been driven through thetubing226 from left to right. As illustrated inFIG. 4, the expansion cone expands thetubing226 including a recess holding slidingring230 which releases the slidingring230 and allows thesleeve220 to return to its natural shape shown inFIG. 21. Upon thus expanding, thesleeve220 contacts theborehole wall232 forming an annular isolator.
• With reference toFIGS. 24 and 25, there is illustrated a system including an external elastomeric bladder which is inflated by fluid in conjunction with expansion ofexpandable tubing section240. Anexpandable bladder242 is carried on the outside of theexpandable tubing240. Also carried on the outside oftubing240 is anannular fluid chamber244. In one end ofchamber244 is a fluid246 and in the other end is acompressed spring248. Between the fluid246 andspring248 is a slidingseal250. Aspring retainer252 within thechamber244 holds thespring248 in a compressed state by means of arelease weld254. Aport256 between thechamber244 and thebladder242 is initially sealed by arupture disk258.
• InFIG. 25, anexpansion cone260 is shown moving from right to left expanding thetubing240. As therelease weld254 is expanded, it breaks free fromspring retainer252 releasing thespring248 to drive the slidingpiston250 to the left which injects the fluid246 through therupture disk258 into thebladder242. Thebladder242 is thus expanded before theexpansion cone260 reaches that part of theexpandable tubing240 which carries thebladder242. As the expansion cone continues from right to left and expands thetubing240, it further drives theinflated bladder242 in firm contact withborehole wall262.
• In a preferred embodiment, thebladder242 is partly filled with achemical compound245 which will react with achemical compound246 carried inchamber244. When thecompound246 is driven into thebladder242, the two chemical parts are mixed and they react to form a solid or semi-solid plastic material and/or expand.
• In theFIG. 24, 25 embodiment, thespring248 can be replaced with other stored energy devices, such as a pneumatic spring. This embodiment can also be operated without a stored energy device. For example, thespring248,retainer252 and thepiston250 may be removed. The entire volume ofchamber244 may then be filled withfluid246. As theexpansion cone260 moves from right to left, it will collapse thechamber244 and squeeze the fluid246 throughport256 into thebladder242. The bladder would be filled before thecone20 moves under it and expands it further astubing240 is expanded.
• It is desirable to provide a pressure relief or limiting arrangement in theFIG. 24, 25 embodiment. If thebladder242 is installed in a nominal or undersized portion of a borehole, it is possible that excessive pressure may be experienced as the expansion cone passes under the bladder. In the above described embodiment in which thechamber244 is filled with fluid and no spring is used, the outer wall ofchamber244 may be designed to expand at a pressure low enough to prevent damage to thebladder242 or theexpansion tool260. A pressure relief valve may also be included in thechamber244 to vent excess fluid if thechamber244 itself expands into contact with a borehole wall.
• With reference now toFIG. 26, there is illustrated anexpandable tubing section266 on which is carried a compressed opencell foam sleeve268 which may be expanded to form an annular isolation device. Thefoam268 is a low or zero permeability open cell foam product which restricts flow in the annular direction. It is elastically compressible to at least 50% of it initial thickness and reversibly expandable to its original thickness. Before running thetubing266 into a well, thefoam sleeve268 is placed over the tubing and compressed axially and held in place by acage270 formed of a series oflongitudinal members272 connected by a series of circular rings274. Thecage270, or at least therings274, are formed of a brittle or low tensile strength material which cannot withstand the normal expansion oftubing266 which occurs when an expansion cone passes through the tubing. Therefore, as the tubing is expanded, for example as illustrated inFIG. 2, thecage270 fails and releases thefoam268 to expand to its original thickness or radial dimension. As this is occurring, thetubing266 itself is expanded pressing thefoam268 against the borehole wall to form an annular isolator.
• Thefoam268 may be made with reactive or swellable compounds carried in dry state within the open cells of the foam. For example, the components of an acid-base cement as discussed with Reference toFIG. 10 or the cross-linked polyacrylamide discussed above with reference toFIG. 11, may be incorporated into the foam. A protective sleeve likesleeve134 ofFIG. 11 may be used to protect the chemicals from fluid contact during installation. After expansion of thetubing266, the chemicals would be exposed to formation fluids and react to form a cement or swellable mass to obtain structural rigidity and impermeability of the expanded foam.
• Other mechanisms may be used to compress thefoam268 as thetubing266 is run into a borehole. For example, helical bands or straps connected to thetubing266 at each end of the foam sleeve could be used. The end connections could be arranged to break on expansion, releasing thefoam268. Alternatively, thefoam268 could be covered by a vacuum shrunk plastic film. Such a film could also protect chemicals incorporated into thefoam268 prior to expansion. The plastic film can be prestretched to its limit, so that upon further expansion by a tubing expansion tool, the film splits, releasing thefoam268 to expand and exposing chemicals to the ambient fluids.
• With reference now toFIG. 27 there is illustrated an annular isolator system using a chemical reaction to provide power to forcibly drive a sleeve into an expanded condition. A section ofexpandable tubing280 carries asleeve282 on its outer surface. Oneend284 of thesleeve282 is fixed to thetubing280. On the other end of thesleeve282 is connected acylindrical piston286 carried between asleeve288 and thetubing280. On the end ofpiston286 is aseal290 between thepiston286 and thesleeve288 on one side and theexpandable tubing280 on the other side. Thesleeve282 may be elastomeric or metallic or may be an expandable metallic sleeve with an elastomeric coating on its outer surface. Twochemical chambers292 and294 are formed between a portion of thesleeve288 and theexpandable tubing280. Arupture disk296 separates thechemical chamber292 from thepiston286. Afrangible separator298 separates thechemical chamber292 fromchamber294.
• In operation of theFIG. 27 embodiment, an expansion cone is driven from left to right expanding the diameter of thetubing280. As the expansion reaches theseparator298, the separator is broken allowing the chemicals inchambers292 and294 to mix and react. In this embodiment, the chemicals would produce a hypergolic reaction generating considerable force to break therupture disk296 and drive thepiston286 to the right in the figure. When this happens, thesleeve282 will buckle and fold outward to contact the borehole wall300. As a forcing cone passes under thesleeve282, it will further compress thesleeve282 against borehole wall300 forming an annular isolator.
• With reference toFIGS. 28 and 29, there is illustrated an embodiment of the present invention using petal shaped plates to form an annular isolator. InFIG. 29, there is illustrated the normal or free-state position of a series ofplates310 carried on anexpandable tubing section312. Each plate has one end attached to the outer surface oftubing312 along a circumferential line around the tubing. The plates are large enough to overlap in the expanded condition shown inFIG. 29. Together theplates310 form a conical barrier between thetubing312 and a borehole wall. For running into the borehole, theplates310 are folded against thetubing312 and held in place by astrap314. The strap orring314 is made of brittle material which breaks upon any significant expansion. As an expansion cone is driven through thetubing312 from left to right, thestrap314 is broken, releasing theplates310 to expand back toward their free state position like an umbrella or flower until they contact a borehole wall. One or more sets of theplates310 may be used in conjunction with other embodiments of the present invention such as those shown inFIGS. 10 and 11. Theplates310 may be used in place of the annular elastomeric rings114,116,126 and128 shown in those figures. Theplates310 may be made of metal and may be coated with an elastomeric material to improve sealing between the individual plates and between the plates and the borehole wall. Alternatively, the plates may be permeable to fluids, but impermeable to gels or to particulates. For example, permeable plates may be used to trap or filter out fine sand occurring naturally in the annulus or which is intentionally placed in the annulus to form an annular isolator.
• Many of the embodiments illustrated in previous figures carry annular isolator forming material on the outer surface of expandable tubing. The material may be a somewhat solid elastomeric material or a fluid material which is injected into the annular space between a section of tubing and a borehole wall to form an annular isolator. To the extent such materials are carried on the external surface of expandable tubing, the overall diameter of the tubing itself must typically be reduced to allow the tubing to be run into a borehole. In addition, any material carried on the outside surface of the tubing are subject to damage during installation in a borehole.
• With reference toFIG. 30, there is illustrated an embodiment in which the annular isolator forming material is carried on the inner surface of an expandable tubing section. InFIG. 30 is shown asection320 of expandable tubing in its unexpanded condition. On the inner surface oftubing320 is carried acylindrical sleeve322 attached at each end to the inner surface oftubing320. The space betweensleeve322 and thetubing320 defines a compartment in which is carried a quantity ofisolator forming material324. Theinner sleeve322 may be of any desired length, preferably less than one tubing section, and may thus carry a considerable quantity ofmaterial324. One ormore ports326 are provided throughexpandable tubing section320 near one end of theinner sleeve322. Theports326 should be positioned at the end opposite the end ofsleeve322 which will be first contacted by an expansion tool.Port326 preferably includes a check valve which allows material to flow from the inside oftubing320 to the outside, but prevents flow from the outside to the inside. If desired, various means can be provided to limit the annular flow ofmaterial324 after it passes through theports326. Annular elastomeric rings328 may be placed on the outer surface oftubing320 to limit the flow of thematerial324. Alternatively, anexpandable bladder330 may be attached to the outer surface ofexpandable tubing320 to confine material which passes through theports326. Theexpandable bladder330 may be formed of an expandable metal sleeve or elastomeric sleeve or a combination of the two.
• In operation, the embodiment ofFIG. 30 will be installed in an open borehole at a location which needs an annular isolator. An expansion cone is then driven throughexpandable tubing320 from left to right. When the expansion cone reaches theinner sleeve322, thesleeve322 is expanded against the inner wall oftubing320 applying pressure tomaterial324 which then flows through theports326 to the outer surface ofexpandable tubing320. Alternatively, thesleeve322 may be designed so that the ends ofsleeve322 slide on or are torn away from the inner surface oftubing320 by the expansion cone. As the cone moves, it can compress the sleeve and squeeze thematerial324 through theports326. The compressedinner sleeve322 would then be forced down hole with the expansion tool. If theouter sleeve330 is used, thematerial324 may be any type of liquid, gas, or liquid like solid (such as glass or other beads) which will inflate thesleeve330 to form a seal with the borehole wall. Ifsleeve330 is used, it is preferred to provide a pressure relief mechanism likearrangement157 shown inFIG. 13. If thesleeve330 is not used, thematerial324 may be any liquid or liquid/solid mix that will solidify or have sufficient viscosity that it will stay where placed, or reactive materials such as acid-base cement or cross linked polyacrylamide taught with reference toFIGS. 10 and 11 above which may be injected through theport326 to contact borehole fluids and form an annular isolator. If therings328 are used to control positioning of reactive materials, it is preferred that therings328 be designed to limit the maximum pressure of such reactive materials.
• For many of the above described embodiments it is desirable that the fluid placed in the annulus to form an isolator be very viscous or be able to change properties when exposed to available fluids in the well annulus. Thixotropic materials which are more viscous when stationary than when being pumped may also provide advantages. Various silicone materials are available with these desirable properties. Some are cured by contact with water and become essentially solid. With further reference toFIG. 30, such a condensate curing silicone material may be injected into the annulus without use of thesleeve330 and with or without the use ofrings328. Such a curable viscous silicone material will conform to any formation wall contour and will fill micro fractures and porosity some distance into the borehole wall which may cause leakage past other types of isolators. This type of curable silicone material may also provide advantages in the embodiments illustrated inFIGS. 11, 12,13 and35. In theFIGS. 12 and 13 embodiments, such a material provides a good material for inflating thesleeves154 and158 and any excess fluid vented into the annulus will cure and form a solid isolator.
• With reference now toFIG. 31, another embodiment which allows maximum diameter of the expandable tubing as run is illustrated. A section ofexpandable tubing336 has a reduceddiameter section338. Within the reduceddiameter section338 areseveral ports340 each preferably including a check valve allowing fluid to flow from inside thetubing336 to the outside. On the outer surface of thetubing336 in the reduceddiameter section338 is carried aninflatable bladder342 sealed at each end to thetubing336.Bladder342 is preferably an elastomeric material. Sincebladder342 is carried on the reduceddiameter section338, its uninflated outer diameter is no greater than the outer diameter oftubing336. Anexpansion cone tool344 is shown expandingtubing336 from left to right. On theexpansion tool344mandrel346 are carriedexternal seals348 sized to produce a fluid tight seal with the inner surface of the reduceddiameter section338 of thetubing336. Themandrel346 includesports345 from its inner fluid passageway to its outer surface. When theexpansion tool344 reaches the point illustrated inFIG. 31, theseals348 form a fluid tight seal with the inner surface of reduceddiameter tubing section338. When that happens, pressurized fluid within theexpansion tool344 flows through theside ports345 onmandrel346 and thetubing ports340 to inflate therubber bladder342. As expansion of thetubing336 is continued, the reduceddiameter zone338 is expanded out to full diameter and the now inflatedbladder342 is forced firmly against the borehole wall to form an annular isolator.
• In a simpler version of theFIG. 31 embodiment, theexpandable bladder342 may be replaced with one or more solid elastomeric rings. For example two or more of the rings shown inFIG. 2 may be mounted in therecess338. The benefit of larger unexpanded tubing diameter is achieved by this arrangement. Theports340 may be eliminated or may be used to inject a fluid, preferably reactive, into the annulus between the rings before or after expansion oftubing336.
• With reference toFIG. 32, there is illustrated an embodiment of the present invention which provides for over expansion of an expandable tubing member to form an annular isolator. InFIG. 32, anexpandable tubing356 is shown in place within aborehole358. Theexpandable tubing356 carries anelastomeric sleeve360 on its outer surface. In place of thesleeve360, several elastomeric rings such as shown inFIG. 2 may be used if desired. Apressure expansion tool362 is shown having been run in from the surface location to the location of thesleeve360. Thetool362 includesseals364 which form a fluid tight seal with the inner wall oftubing356. Thetool362 includesside ports366 located between seals364. It preferably includes apressure relief valve367. After theexpansion tool362 is positioned as shown, fluid is pumped from the surface into thetool362 at sufficient pressure to expand and overexpand thetubing356. When theelastomeric sleeve360 contacts theborehole wall358 an increase in pressure will be noted and expansion can be stopped. The relief valve limits the pressure to avoid rupturing thetubing356. Thetool362 may be moved on through thetubing356 to other locations where external sleeves such as360 are carried and expand them into contact with theborehole wall358 to form other annular isolators.
• The expansion system shown inFIG. 32 may be used either before or after normal expansion of thetubing356. If it is performed before normal expansion, thetool362 may carry an adjustable expansion cone or may pick up a cone from the bottom of the tubing string for expansion as thetool362 is withdrawn from thetubing356. If performed after normal expansion of thetubing356, theseals364 may be inflatable seals allowing isolation of the zones which need over expansion after the normal expansion process is performed.
• With reference toFIGS. 33 and 34, a system for over expansion of expandable tubing using hydroforming techniques is illustrated. InFIG. 33, a section ofexpandable tubing370 carrying anelastomeric sleeve372 on its outer surface is illustrated. In order to expand theannular barrier area372, a pair ofslips374 are positioned on the inside oftubing370 on each side of thebarrier372. Forces are then applied driving the slips towards one another and placing the portion oftubing370 under therubber sleeve372 in compression. The axial compression reduces the internal pressure required to expandtubing370 and allows it to expand to a larger diameter without rupturing. The pressure within thetubing370 may be then raised to expand the section which is in axial compression caused by theslips374. As a result of the axial loading and the internal pressure, the tubing will expand as shown inFIG. 34 until therubber sleeve372 contacts the borehole wall376. This will cause an increase of pressure which indicates that an annular isolator has been formed. Theslips374 may then be released and moved to other locations for expansion to form other annular isolators. If desired, the expansion tool shown inFIG. 32 may be used in conjunction with the slips shown inFIGS. 33 and 34 so that the expansion pressure may be isolated to the annular barrier area of interest. Aconduit378 may be positioned through therubber sleeve372 for providing power, control, communications signals, etc. to and from down hole equipment as discussed above with reference toconduit45 inFIG. 2.
• With reference toFIG. 35, there is illustrated an embodiment of the present invention which allows formation of a conforming annular isolator after expansion of expandable tubing. InFIG. 35, there is illustrated a section ofexpandable tubing380 positioned within anopen borehole382. Thetubing380 carries a pair ofelastomeric rings384 and386. This is the same arrangement as illustrated inFIG. 2. After expansion of thetubing380 using a conventional expansion cone, it is seen that theexpansion ring386 has been compressed between theborehole wall382 and thetubing380 to form a seal while theexpansion ring384 may not be tightly sealed against the borehole wall since it has been expanded into an enlarged portion of theborehole382. It is desirable that therings384 and386 be designed to limit the pressure of injected materials.Expanded tubing380 includes one ormore ports388 which may preferably include check valves. Afluid injection string390 which may be similar to thedevice362 shown inFIG. 32, is shown in place within expandedtubing380.Injection string390 includesseals392 on either side of aport394 through theinjection tool390. With theinjection tool390 in position as illustrated, various annular isolator forming materials may be pumped from the surface throughports394 and388 into the annular space between expandedtubing380 and theborehole wall382. The elastomeric rings384 and386 tend to keep the injected material from flowing along the annulus. Aconduit394 may be positioned through therings384 and386 for providing power, control, communications signals, etc. to and from down hole equipment as discussed above with reference toconduit45 inFIG. 2.
• In the embodiment ofFIG. 35, various materials may be pumped to form the desired annular isolator. Chemical systems of choice would be those which could be injected as a water thin fluid and then attain efficient viscosity to isolate the annulus. Such chemical systems include sodium silicate systems such as those used in the Angard™ and Anjel® services provided by Halliburton Energy Services. Resin systems such as those disclosed in U.S. Pat. No. 5,865,845 (which is hereby incorporated by reference for all purposes) owned by Halliburton and those used in the ResSeal™, Sanfix®, Sanstop™ or Hydrofix™ water shutoff systems provided by Halliburton would also be useful. Crosslinkable polymer systems such as those provided in Halliburton's H2Zero™ and PermSeal™ services would also be suitable. Emulsion polymers such as those provided in Halliburton's Matrol™ service may also create a highly viscous gel in place. Various cements may also be injected into the annulus with this system. The system ofFIG. 35 is particularly useful if the surrounding formation has excessive porosity. The injected fluid may be selected to penetrate into the formation away from theborehole wall382 to prevent fluids from bypassing the annular isolator by flowing through the formation itself.
• The petal plate embodiment ofFIGS. 28 and 29 may be used in place of therings384 and386 shown inFIG. 35. They may be particularly useful for forming a annular isolator using fine sand as annular isolation material. A premixed slurry of fine sand can be pumped outsidetubing380 between a pair of the petal plate sets310. Theplates310 should filter out and dehydrate the sand as pressure is increased. It is believed that such a sand pack several feet long would provide a good annular isolator blocking the annular flow of produced fluids. This embodiment may also form a sand annular isolator by catching or filtering out naturally occurring sand which is produced from the formations and flows in the annulus.
• With reference toFIG. 36, there is illustrated another system for preexpanding an externally carried elastomeric sleeve of the type shown in FIGS.6 to9. A section ofexpandable tubing400 is shown being expanded from left to right by anexpansion tool402. A foldableelastomeric sleeve404, which may be identical tosleeve80 ofFIG. 6, is carried on the outer surface oftubing400. On the right end ofsleeve404 is a stop ring406 which may be identical to thering82 ofFIG. 6. Anouter metal sleeve408 is carried ontubing400 adjacent the left end of thesleeve404, and has slidingseals410 between the inner surface ofsleeve408 and the outer surface oftubing400. An inner slidingsleeve412 is positioned at the location of theouter sleeve408 and connected to it by one or more bolts or pins414. Thepins414 may slide axially in correspondingslots416 through thetubing400.
• In operation of theFIG. 36 embodiment, theleading edge418 ofexpansion tool402 is sized to fit within the unexpanded inner diameter oftubing400 and to push theinner sleeve412 to the right. As the expansion tool is driven to the right, it pushes thesleeve412, which in turn pushesouter sleeve408 to the right by means of thepins414 which slide to the right inslots416. When thepins414 reach the right end of theslots416, thesleeve404 will have been folded as illustrated inFIG. 6. Further movement ofexpansion tool402 shears off thepins414 so that theinner sleeve412 may be pushed on down thetubing400. As theexpansion tool402 passes throughtubing400,outer sleeve408 and thesleeve404, all of these parts are further expanded as illustrated inFIG. 7. The inner surface ofsleeve408 preferably carries a toothedgripping surface420, like thesurface59 ofFIG. 4. Whensleeve408 has moved to the right, grippingsurface420 will be adjacent the outer surface oftubing400. Upon expansion of thetubing400, it will grip thetoothed surface420 preventing further sliding of theouter ring408. The ring406 may be adapted to slide in response to excessive expansion pressures created by undersized boreholes as discussed above with reference toFIGS. 3 and 4.
• With reference toFIG. 37, there is illustrated yet another system for preexpanding an externally carried elastomeric sleeve of the type shown in FIGS.6 to9. A section ofexpandable tubing500 is shown being expanded from left to right by anexpansion tool502. A foldableelastomeric sleeve504, which may be identical tosleeve80 ofFIG. 6, is carried on the outer surface oftubing500. On the right end ofsleeve504 is astop ring506 which may be identical to thering82 ofFIG. 6. On the left end ofsleeve504 is attached aslidable ring508. Asleeve510 is slidably carried on the inner surface oftubing500. A pair of slidingseals512 provide fluid tight seal betweensleeve510 and the inner surface oftubing500. One or more pins514 are connected to and extend radially from theinner sleeve510. The pins514 extend through corresponding slots516 in thetubing500 and are positioned adjacent the left end of thering508. Thering508 preferably carries gripping teeth518 on its inner surface.
• In operation of theFIG. 37 embodiment, theexpansion tool502 is forced from left to right through thetubing500. When thetool502 reaches anedge520 of theinner sleeve510, it will begin to push thesleeve510 to the right. Thesleeve510, through pins514, pushes theouter ring508 to the right compressing andfolding sleeve504 into the shape shown inFIG. 6. When the pin514 reaches the end of slot516, thesleeve510 stops moving to the right. Theedge520 ofinner sleeve510 is preferably sloped to match the shape ofexpansion tool502 and limit the amount of force which can be applied axially before thesleeve510 stops and is expanded by thetool502. Thetool502 then passes throughsleeve510 expanding it, thetubing500, theouter ring508 and thesleeve504. As this occurs, the teeth518 grip the outer surface oftubing500 to resist further slipping of thering508. Thering506 may be adapted to slide in response to excessive expansion pressures created by undersized boreholes as discussed above with reference toFIGS. 3 and 4.
• The embodiments ofFIGS. 12 through 16 and30 (with the inflatable sleeve330) share several functional features and advantages. These are illustrated in a more generic form inFIGS. 38 through 41. Each of these embodiments provides a recess or compartment in an expandable tubing in which a flowable material used to form an annular isolator is carried with the expandable tubing when it is run into a borehole. In each embodiment it is desirable that sufficient material be carried with the tubing to form an annular isolator in an oversized, washed out and irregular shaped borehole. It is also desirable that the same systems function properly in a nominal or even undersized borehole. In each of these embodiments, an expandable outer sleeve has certain characteristics which make this multifunction capability possible.
• InFIG. 38, a section of expandedtubing530 is shown in anopen borehole532 having an enlarged or washed outportion534. Aninflatable sleeve536 is shown having afirst portion538 inflated into contact with theenlarged borehole portion534. Thesleeve portion538 is designed to allow great expansion at a first pressure level to form an annular isolator in anenlarged borehole wall534. It may be made of elastomeric material or expandable metal which is corrugated or perforated or otherwise treated to allow greater expansion. Ifsleeve536 is corrugated or perforated, it is preferably covered with an elastomeric sleeve.Other portions540,542 of thesleeve536 are designed to inflate at pressures higher than the pressure required to inflate thesection538. The volume of fluid carried in thetubing530 as it is run in or installed in theborehole532 is selected to be sufficient to inflatesleeve section538 to its maximum allowable size.
• With reference toFIG. 39, an end view of theenlarged borehole section538,tubing530 andisolator sleeve section538 ofFIG. 38 is shown. As illustrated, theborehole section534 may not only be enlarged, but may have an irregular shape, width greater than height and the bottom may be filled with cuttings making it flatter than the top. The flexibility ofsleeve section538 allows it to conform to such irregular shapes. The volume of inflating fluid carried in thetubing530 should be sufficient to inflate thesleeve536 into contact with such irregular shaped holes so long as it does not exceed the maximum allowable expansion of the sleeve.
• InFIG. 40 is illustrated thesame tubing530 andsleeve536 is aborehole section544 which is enlarged, but less enlarged than the washed outsection534 ofFIG. 38. InFIG. 40 thesleeve section538 has expanded into contact with the borehole wall at a smaller diameter than was required inFIG. 38. Only part of the fluid volume carried in thetubing530 was required to expandsleeve section538. As thetubing530 was expanded after thesection538 contacted the borehole wall, the expansion fluid pressure increased to a higher level at which thesleeve section540 expands. Thesection540 has also expanded into contact with theborehole wall544. In thisFIG. 40, the volume of expansion fluid required to expand bothsections538 and540 into contact with the borehole wall is the same as the amount carried down hole with thetubing530. Complete expansion of thetubing530 therefore does not cause further inflation of thesleeve536.
• InFIG. 41, the expandedtubing530 is shown installed in a borehole546 which is not washed out. Instead the borehole546 is of nominal drilled diameter or may actually be undersized due to swelling on contact with drilling fluid. In this case, theouter sleeve section538 first expanded into contact with the borehole at a first pressure level. The expansion fluid pressure then increased causing thesleeve section540 to expand into contact with the borehole wall546. Inflation of these sections required only part of the volume of fluid carried in thetubing530. As a result, the fluid pressure increased to a third level at whichsleeve section542 expanded into contact with the borehole546. In this illustration, the volume of fluid needed to expand allsections538,540 and542 into contact with the borehole wall was less than the total available amount of fluid carried intubing530. As a result, the fluid pressure increased to a fourth level at which a pressure relief valve released excess fluid into the annulus at548.
• An inflatable sleeve as illustrated inFIGS. 38-41 may have two, three or more separate sections which expand at different pressures and may or may not include pressure relief valves. The embodiments ofFIGS. 12 and 13 have two sleeve sections which expand at different pressures and a relief valve which opens at a third higher pressure. The embodiment ofFIGS. 15 and 16 has three sleeve sections, each of which expands at a different pressure level, and as illustrated does not have a pressure relief valve. TheFIG. 15, 16 embodiment may be provided with a pressure relief valve to protect the system from excessive pressure if desired. The combinations of these elements provides for maximum inflation to form an annular isolator in a large irregular borehole, while allowing the same system to be inflated to form an annular isolator in a nominal or undersized borehole without causing excessive pressures or forces which may damage the annular isolator forming sleeve, ring, etc., the tubing or an expansion tool.
• InFIGS. 2, 10,33,34 and35 there are illustrated conduits located in the annulus and passing through the annular isolators formed by those embodiments. With reference toFIGS. 42, 43 and44 there are illustrated more details of embodiments including such conduits. InFIG. 42, a section ofexpandable tubing550 has a reduceddiameter section552. An outerinflatable sleeve554 extends across therecess552 to form a compartment for carrying an isolator forming material. Anexternal conduit556 passes through thesleeve554. Theconduit556 may have anopening557 into the compartment betweenrecess552 andsleeve554.FIG. 43 provides a more detailed view of a sealing arrangement between thesleeve554 and theconduit556 ofFIG. 42. Arubber gasket558 may be positioned in anopening560 through each end of thesleeve554 as illustrated. Theconduit556 may be inserted through thegasket558. The gasket forms a fluid tight seal between theconduit556 and thesleeve554 to prevent flow of fluids between the annulus and the compartment betweensleeve554 and thetubing recess552.
• FIG. 44 illustrates another arrangement for providing one or more conduits in the annulus where an annular isolator is positioned. Aninflatable sleeve561 is carried on anexpandable tubing562, forming a compartment in which an annular isolator forming material may be carried down hole with thetubing562. Thesleeve561 has alongitudinal recess564 in which is carried twoconduits566. Arubber gasket568 has external dimensions matching therecess564 and two holes for carrying the twoconduits566. When thesleeve561 is expanded into contact with a borehole wall to form an annular isolator, thegasket568 will act as an annular isolator for that portion of the annulus between theconduits566 and thesleeve561 and will protect theconduits566.
• As discussed above,conduits556 and566 may carry various copper or other conductors or fiber optics or may carry hydraulic fluid or other materials. In theFIG. 42 embodiment, theside port557 may be used to carry fluid for inflating thesleeve554 if desired. The conduit may pass through a series ofsleeves554 and they may all be inflated to the same pressure with asingle conduit556 havingside ports557 in each sleeve. Theconduit556 may be used to deliver one part of a two part chemical system with the other part carried down hole with the tubing. Theconduit556 may be used to couple electrical power to heaters to activate chemical reactions. Either electrical power or hydraulic fluid may be used to open and close valves which may control inflation of annular isolators during installation of a production string, or may be used during production to control flow of produced fluids in each of the isolated producing sections. The dual conduit arrangement ofFIG. 44 may provide two hydraulic lines which can be used to control and power a plurality of down hole control systems.
• With reference toFIG. 45, there is illustrated anelastomeric sleeve580 which may be used as an alternative tosleeve56 ofFIG. 3,sleeves80 and88 ofFIG. 6, or thesleeve220 ofFIG. 21. Thesleeve580 is illustrated in an unrestrained or as-molded shape. Eachend582 is a simple cylindrical elastomeric sleeve. Between theends582 are a series ofcircumferential corrugations584. Thecorrugations584 have innercurved portions586 having an inner diameter corresponding to the inner diameter ofend portions582. This inner diameter is sized to fit on the outer surface of an unexpanded expandable tubing section. The maximum diameter ofcorrugations584 is sized to contact or come close to the wall of a washed out borehole section without tubing expansion. If desired,wire bands588 may be used to maintain the corrugated shape when thesleeve580 is compressed as discussed below.
• In use, thesleeve580 is attached to expandable tubing with a sliding ring likering60 and a fixed ring likering58 ofFIG. 3. Thesleeve580 is then stretched axially until the corrugations are substantially flattened against the tubing and the sliding ring is latched into a restraining recess. Note that axial stretching of the elastomer is not essential to flattening the corrugations. The flattenedsleeve580 is then carried with the tubing as it is installed in a borehole. Upon expansion of the tubing in the borehole, the sliding ring will be released as shown inFIG. 4 and will tend to return to its corrugated shape. As expansion continues the sliding ring will be pushed by the expansion cone as shown inFIGS. 6 and 7 to axially compress thesleeve580. Thesleeve580 will take the form shown inFIG. 45 and then be further compressed until thecorrugations584 are tightly pressed together. Thewire bands588 are preferred to maintain the shape after full compression. The alternative axial compression and radial expansion systems shown inFIGS. 36 and 37 may be used with thesleeve580 if desired. It can be seen that by molding thesleeve580 in the form shown inFIG. 45, the sleeve will have a small radial height as run into the borehole and a very predictable radial height after it has been released and returned to its corrugated shape. As with other embodiments described herein, thesleeve580 will then be further expanded with the expandable tubing as the expanding tool passes under thesleeve580.
• As noted above in the descriptions of various embodiments, various fluids may be used in the present invention to inflate an external sleeve, bladder, etc. to form an annular isolator or may be injected directly into the annulus between tubing and a borehole wall to form an annular isolator by itself or in combination with external elastomeric rings, sleeves, etc. carried on the tubing. These fluids may include a variety of single parts liquids which are viscous or thixotropic as carried down hole in the tubing. They may include chemical systems which react with ambient fluids to become viscous, semisolid or solid. They may also include flowable solid materials such a glass beads. In many of the above described embodiments an annular isolator is formed of a viscous or semisolid material either directly in contact with a borehole wall or used as a fluid to inflate a metallic and/or elastomeric sleeve. These arrangements not only provide annular isolation in an irregular or enlarged borehole wall, but also allow the isolation to be maintained as the shape or size of the borehole changes which often occurs during the production lifetime of a well.
• As is apparent from the above described embodiments, it is desirable to provide external elastomeric sleeves, rings, etc. which are of minimal diameter during running in of tubing, but which expand sufficiently to form an annular isolator in irregular and enlarged open borehole. By proper selection of elastomeric materials, it can swell upon contact with well bore fluids or setting fluids carried in or injected into production tubing. For example, low acrylic-nitrile swells by as much as fifty percent when contacted by xylene. Simple EPDM compounds swell when contacted by hydrocarbons. This approach may provide additional expansion and isolation in the embodiments shown inFIGS. 2, 4,5,6,12,15,19,22,25,30,31,32,34 and35. It may be desirable to encase the swellable elastomer inside a nonswellable elastomer. Elastomers which have been expanded by this method may lose some physical strength. A nonswellable outer layer would also prevent loss of the swelling agent and shrinkage of the swellable material. For example in the embodiment ofFIG. 30, theelastomeric sleeve330 can be made of two layers, with the inner layer swellable and the outer layer not swellable. The fluid324 can be selected to cause the inner layer to swell. The fluid324 and inner layer of elastomer would tend to fill the expandedmember330 with a solid or semisolid mass.
• It is often desirable for the inflating fluids described herein to be of low viscosity while being used to inflate a sleeve or being pumped directly into an annulus. Low viscosity fluids allow some of the fluid to flow into microfractures or into the formation to help stop fluids from bypassing the annular isolator. But it is also desirable to have the injected fluids become very viscous, semisolid or solid once in place. Many two part chemical systems are available for creating such viscous, semisolid, rubbery or solid materials. Some, for example the silicone materials or the polyacrylamide materials, react with available water to form a thick fluid. Others require a two part chemical system or a catalyst to cause the chemicals to react. TheFIG. 10 embodiment delivers two chemical components in dry condition to be reacted together with ambient water. TheFIG. 24 embodiment delivers and mixes a two part chemical system to the location where an annular isolator is needed. In the embodiment ofFIGS. 13 and 14, thecorrugated tubing section160 provides four separate compartments in which various chemical systems may be carried with the tubing as installed to be mixed upon expansion of the tubing. In other embodiments, such as those shown inFIGS. 12 through 16, the delivery system includes a single recess or compartment. In these embodiments, a two part chemical system can be used by encapsulating one part of the chemical system, or a catalyst, in bags, tubes, microspheres, microcapsules, etc. carried in the other part of the chemical system. By selecting the sizes and shapes of such containers, they will rupture during the expansion process allowing the materials to mix and react. For example, in theFIG. 30 embodiment, theport326 can be shaped to cause rupturing of such bags, tubes, microcapsules, etc. and mixing of the materials as they pass through the port.
• As noted above, any one of theannular isolators28,30,36,38 shown inFIG. 1, may actually comprise two or more of the individual isolators illustrated in other figures. If desired, pairs of such individual isolators may be arranged closely to provide separate recesses or storage compartments for carrying each part of a two part chemical system in the tubing, to be mixed only after tubing expansion. For example, an embodiment according toFIG. 12 or13 could be spaced a short distance up hole from an embodiment likeFIG. 11. TheFIG. 11 embodiment could carry a catalyst for the material carried in theFIG. 12 or13 embodiment. Excess fluid vented through the pressure relief mechanism of theFIG. 12 or13 embodiment would be vented down hole toward theFIG. 11 embodiment, which upon expansion would release the catalyst into the borehole causing the vented fluid to become viscous, semisolid or solid. In similar fashion, theFIG. 30 embodiment could include twointernal sleeves322 each carrying one part of a two part chemical system and each having aport326 located between the pair of elastomeric rings328. Upon expansion, both parts of the chemical system would be injected into the annulus and isolated betweenrings328 to mix and react. Alternatively, any one of the described individual isolators may include one of the one-component chemicals or swellables to be ejected from the relief system and form an annular isolator on contact or reaction with the ambient fluids in the annulus. Under either of these approaches, both a mechanical isolator or isolators (e.g. the inflatable member(s)) and a chemical or swellable isolator (formed as a result of the materials ejected through the relief systems into the annulus) are formed in proximity to each other in the same annulus.
• In the embodiments illustrated inFIGS. 11-16,24,25,30, and3841, an annular isolator forming material is preferably carried down hole in a reservoir or compartment formed in part by a tubing wall. InFIGS. 11-16 the inflation fluid compartment is formed between a reduced diameter portion of the tubing and an outer sleeve. InFIG. 30, a compartment is formed between an inner sleeve and the inside surface of a tubing. In either case, the material is carried down hole with the tubing as it is run in or installed in the borehole. It is preferred that the compartment be entirely, or at least in part, located within the outer diameter of the tubing as it is run in the borehole. This allows a sufficient volume of material to inflate a sleeve or bladder, or to form an annular isolator in the annulus, to be carried down hole, but does not require, or minimizes, reduction in the tubing diameter to provide an overall system diameter small enough to be installed in the borehole. It is desirable for the tubing to have the largest possible diameter as installed, so that upon expansion it can reduce the annulus size as much as possible.
• Many of the above-described embodiments include the use of an expansion cone type of device for expansion of the tubing. However, one of skill in the art will recognize that many of the same advantages may be gained by using other types of expansion tools such as fluid powered expandable bladders or packers. It may also be desirable to use an expandable bladder in addition to a cone type expansion tool. For example, if a good annular isolator is not achieved after expansion with a cone type tool, an expandable bladder may be used to further expand the isolator to achieve sealing contact with a borehole wall. An expandable bladder may also be used for pressure or leak testing an installed tubing string. For example, an expandable bladder may be expanded inside the tubing at the location where an annular isolator has been installed according to one of the embodiments disclosed herein. The tubing may be pressured up to block flow in the tubing itself to allow detection of annular flow past the installed isolator. If excessive leakage is detected, the bladder pressure may be increased to further expand the isolator to better seal against the borehole wall.
• In many of the above described embodiments the system is illustrated using an expansion tool which travels down hole as it expands expandable tubing and deploys an annular isolator. Each of these systems may operate equally well with an expansion tool which travels up hole during the tubing expansion process. In some embodiments, the locations of various ports and relief valves may be changed if the direction of travel of the expansion tool is changed. For horizontal boreholes, the term up hole means in the direction of the surface location of a well.
• Similarly, while many of the specific preferred embodiments herein have been described with reference to use in open boreholes, similar advantages may be obtained by using the methods and structures described herein to form annular isolators between tubing and casing in cased boreholes. Many of the same methods and approaches may also be used to advantage with production tubing which is not expanded after installation in a borehole, especially in cased wells.
• While the present invention has been illustrated and described with reference to particular apparatus and methods of use, it is apparent that various changes can be made thereto within the scope of the present invention as defined by the appended claims.

Claims (13)

1. A system for forming an annular isolator between tubing and a borehole comprising:

a section of expandable tubing,

an elastomeric sleeve carried on the outer wall of said tubing,

said sleeve having a generally cylindrical shape having a first axial dimension and a first radial dimension when free of external forces and, in response to axial compressive force, having a second axial dimension shorter than said first axial dimension and a second radial dimension greater than said first radial dimension, and

means for applying axial compressive force to said sleeve in a borehole.

2. The system ofclaim 1, wherein said sleeve has a first end and a second end, further comprising:

a first ring coupled to said sleeve first end and coupled to said tubing,

a second ring coupled to said sleeve second end and slidably coupled to said tubing, and

said second ring shaped to slide axially along said tubing and apply compressive force to said sleeve in response to expansion of said tubing by a cone type expansion tool.

3. The system ofclaim 2, wherein said first ring is frictionally coupled to said tubing, with a friction coefficient selected to relieve axial compression forces in said sleeve above a preselected level.

4. The system ofclaim 2, wherein said second ring is frictionally coupled to said tubing, with a friction coefficient selected to relieve axial compression forces in said sleeve above a preselected level.

5. The system ofclaim 2, further comprising an internal sleeve slidably carried within said tubing and coupled to said second ring, said internal sleeve shaped to engage and move with a cone type expansion tool moving through said tubing and to move said second ring axially on said tubing.

6. The system ofclaim 1, wherein said sleeve is adapted to fold upon itself in response to axial compressive force.

7. The system ofclaim 6, wherein said sleeve includes a plurality of circular regions of reduced thickness defining fold lines.

8. The system ofclaim 1, wherein:

said tubing comprises two sections coupled by a threaded connection,

said elastomeric sleeve is carried between said two sections,

whereby upon making up of the threaded connection an axial compressive force is applied to said elestomeric sleeve.

9. The system ofclaim 8, further including:

a work string adapted to rotatably engage one of said two sections,

whereby upon rotation of said work string, axial compressive force may be applied to said elastomeric sleeve.

10. The system ofclaim 1, further comprising:

a cylinder divided into first and second chambers by a seal adapted to break upon expansion of said tubing,

a first part of two part hypergolic chemical system in said first chamber,

a second part of two part hypergolic chemical system in said second chamber, and

a piston in said cylinder coupled to said sleeve,

whereby upon expansion of said tubing and breaking of said seal, a hypergolic reaction drives said piston to compress said seal.

11. The system ofclaim 1, wherein said elastomeric sleeve comprises a material which swells upon contact with a fluid in a borehole.

12. The system ofclaim 11, wherein the material comprises a low acrylic-nitril.

13. The system ofclaim 11, wherein the material comprises an EPDM compound.

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