US20030075337A1 - Method of expanding a tubular member in a wellbore - Google Patents

Abstract

The present invention provides methods for expanding a tubular with the aid of a compressive force. A tubular, such as a string of casing, is run into a wellbore on a working string, e.g., drill pipe. A carrying mechanism such as a collet is used to releasably attach the first tubular to the working string during run-in. The tubular is then expanded into frictional engagement with another tubular therearound within the wellbore. During the expansion process, a compressive force is applied to the portion of the tubular being expanded. In one aspect of the invention, a hydraulic ram is positioned above the string of casing and is activated by the injection of fluid under pressure in order to apply the compressive force to the expandable tubular. In another aspect of the invention, the portion of casing or other expandable tubular to be expanded is pre-stressed, such as to impart a barrel shape, in order to bias the tubular to more easily buckle outwardly during expansion.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention[0001]
• The present invention relates to methods for wellbore completions. More particularly, the invention relates to completing a wellbore by expanding tubulars therein. More particularly still, the invention relates to the expansion of a tubular within a wellbore through the use of compressive forces.[0002]
• 2. Description of the Related Art[0003]
• Hydrocarbon and other wells are completed by forming a borehole in the earth and then lining the borehole with steel pipe or casing to form a wellbore. After a section of wellbore is formed by drilling, a section of casing is lowered into the wellbore and temporarily hung therein from the surface of the well. Using apparatus known in the art, the casing is cemented into the wellbore by circulating cement into the annular area defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.[0004]
• It is common to employ more than one string of casing in a wellbore. In this respect, a first string of casing is set in the wellbore when the well is drilled to a first designated depth. The first string of casing is hung from the surface, and then cement is circulated into the annulus behind the casing. The well is then drilled to a second designated depth, and a second string of casing, or liner, is run into the well. The second string is set at a depth such that the upper portion of the second string of casing overlaps the lower portion of the first string of casing. The second liner string is then fixed or “hung” off of the existing casing by the use of slips which utilize slip members and cones to wedgingly fix the new string of liner in the wellbore. The second casing string is then cemented. This process is typically repeated with additional casing strings until the well has been drilled to total depth. In this manner, wells are typically formed with two or more strings of casing of an ever decreasing diameter.[0005]
• Apparatus and methods are emerging that permit tubulars to be expanded in situ. The apparatus typically includes expander tools which are fluid powered and are run into the wellbore on a working string. The hydraulic expander tools include radially expandable members which, through fluid pressure, are urged outward radially from the body of the expander tool and into contact with a tubular therearound. As sufficient pressure is generated on a piston surface behind these expansion members, the tubular being acted upon by the expansion tool is expanded past its point of plastic deformation. In this manner, the inner and outer diameter of the tubular is increased in the wellbore. By rotating the expander tool in the wellbore and/or moving the expander tool axially in the wellbore with the expansion member actuated, a tubular can be expanded along a predetermined length in a wellbore.[0006]
• Multiple uses for expandable tubulars are being discovered. For example, an intermediate string of casing can be hung off of a string of surface casing by expanding a portion of the intermediate string into frictional contact with the lower portion of surface casing therearound. This allows for the hanging of a string of casing without the need for a separate slip assembly. Additional applications for the expansion of downhole tubulars exist. These include the use of an expandable sand screen, employment of an expandable seat for seating a diverter tool, and the use of an expandable seat for setting a packer.[0007]
• There are problems associated with the expansion of tubulars. One problem particularly associated with rotating expander tools is the likelihood of obtaining an uneven expansion of a tubular. In this respect, the inner diameter of the tubular that is expanded tends to assume the shape of the compliant rollers of the expander tool, including imperfections in the rollers. Also, the inside surface of the tubular is necessarily roughened by the movement of the rollers of the expander tool during expansion. Moreover, the compliant rollers are of a limited length, meaning that the working string must be moved up and down in order to apply the actuated rollers to different depths of a tubular to be expanded. This creates the likelihood that some portions of a tubular may be missed in the expansion process. The overall result is that the inner diameter of the expanded tubular no longer has a uniform inner circumference. This problem is exacerbated by the amount of force needed to expand many tubulars members.[0008]
• Another problem encountered pertains to a change in wall thickness which results from the expansion of a tubular, regardless of the type of expander employed. It has been discovered that the expansion process results in a reduction in wall thickness of that portion of casing or other tubular being expanded. As the wall begins to thin, the amount of force needed to expand that portion of tubular decreases. The roller or other expander member tends to push the tubular material out radially at the expense of the material on the flanks of the roller. The tubular material in the flank region essentially acts as a sacrificial zone for the expansion process as it provides the bulk of the material for the expansion process.[0009]
• There is a need, therefore, for an improved method for expanding a portion of casing or other tubular within a wellbore. Further, there is a need for expanding a tubular downhole which alleviates the problem of pipe thinning. Still further, a need exists for expanding a tubular which requires less outward force against the inner surface of the tubular. There is yet a further need for a method for expanding a tubular which reduces the risk of uneven expansion of the tubular by reducing the amount of force needed for the expansion operation.[0010]
SUMMARY OF THE INVENTION
• The present invention provides methods for expanding a tubular within a wellbore. According to the present invention, the tubular to be expanded is run into a wellbore on a working string. The tubular is supported by a collet or other carrying mechanism at the lower end of the working string.[0011]
• Above the collet is an expander tool. The expander tool is a rotary expander tool, meaning it is rotated by rotating the working string or, perhaps, a rotary mud motor. The expander tool employs a series of rollers which are actuated by hydraulic pressure. In this regard, the expander tool has a hollow bore in fluid communication with a series of rollers. Injection of fluid under pressure into the working string causes the rollers to move outwardly from the body of the expander tool, and to apply an outward force against the inner surface of the expandable tubular.[0012]
• Above the expander tool, and also in series with the working string, is a hydraulically actuated ram. The ram is positioned on top of the tubular to be expanded, such as a lower string of casing, or liner. The ram has a mandrel which serves as a tubular for transporting fluids from the working string downward to the expander tool. The ram further has a body surrounding the mandrel. An annulus is thus defined between the mandrel and the body.[0013]
• Seals are circumferentially fitted between the mandrel and an inner surface of the body in order to seal the annulus. The diameter of the annulus is greater at the location of the upper seal than at the location of the lower seal. Thus, a difference in cross-sectional area is provided within the sealed annulus. Because the[0014]lower casing string140 is held in place by the carryingmechanism150, a compressive force is applied to thelower casing string140 along the portion designated for expansion.
• A through-opening is placed in the mandrel between the upper seal and the lower seal. The through-opening allows fluid to flow down the working string, through the mandrel, and into the annulus. The annulus is sealed above and below the through-opening by the upper and lower seals. Thus, fluid under pressure is injected into an annular region defined by the body, the mandrel, and the upper and lower seals. The application of pressure in the annulus acts on the net hydraulic area between the upper and lower seals to create a downward force. The result is that fluid injected into the annulus applies a force downward against the expandable tubular. At the same time, the expandable tubular is supported and held in place within the wellbore by the carrying mechanism at the lower end of the working string. Thus, a compressive force is exerted onto that portion of the tubular to be expanded.[0015]
• Once the compressive force is applied, the expander tool is actuated against the inner surface of the expandable tubular. In one aspect, the expandable tubular is a portion of a string of casing, or liner. The expander tool acts against the lower string of casing, causing the lower string of casing to be expanded radially into a surrounding string of casing. The application of compressive force serves to assist in the expansion process, meaning that less radial force is needed in order to achieve a sufficient frictional engagement between the two strings of casing. Further, a more uniform wall thickness and expansion job is achieved.[0016]
• Optionally, and in addition, a bias is machined into that portion of a tubular to be expanded. For example, the tubular could be pre-stressed outwardly into a barrel configuration. This would cause the tubular to more readily buckle outwardly upon application of an expansive force from within the expandable tubular, thus aiding the expander rollers. This process, in turn, would further alleviate the thinning effect which would otherwise occur on the flanks of the expander members. The ultimate benefit is a stronger transition zone that will carry more weight axially and also enjoy stronger resistance to collapse.[0017]
BRIEF DESCRIPTION OF THE DRAWINGS
• So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.[0018]
• FIG. 1 is a cross-sectional view of a wellbore having an upper string of casing. In this view, a lower string of casing has been run into the wellbore on a working string. Also visible at a lower end of the working string is an expander tool for expanding the lower string of casing at the desired depth in the wellbore, and a hydraulic ram for applying a compressive load onto the lower string of casing during the expansion process.[0019]
• FIG. 2 is an exploded view of a rotary expander tool as might be used in the methods of the present invention.[0020]
• FIG. 3 is an enlarged sectional view of a hydraulic ram as might be used to apply a compressive load onto an expandable tubular during the expansion process.[0021]
• FIG. 4 is a sectional view of a wellbore having an upper string of casing, and showing a lower string of casing being expanded into frictional contact with the upper string of casing. In this view, a compressive load is being applied to the lower string of casing. Further, the rollers of the expander tool are being activated and rotated.[0022]
• FIG. 5 is a sectional view of the wellbore of FIG. 4, showing the portion of expandable tubular in complete, frictional communication with the upper string of casing. The working string and associated tools are being removed from the wellbore.[0023]
• FIG. 6 is a partial section view of the wellbore of FIG. 5, illustrating the upper section of the lower casing string expanded into the upper casing string after the expander tool and run-in string have been removed. This view more fully illustrates the portion of the lower string of casing, including optional slip and sealing members, having been expanded into the upper string of casing therearound.[0024]
• FIG. 7 is a cross-sectional view of a wellbore illustrating an alternate means for assisting in the expansion of a tubular. Visible in this view is a barrel-shaped configuration for a portion of the expandable tubular where expansion is to begin.[0025]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• FIG. 1 is a cross-sectional view of a[0026]wellbore100 having an upper string ofcasing110 disposed therein. The upper string ofcasing110 has been set within thewellbore100 through a cementing process. The cement layer is visible in theannulus120, defined by the upper string ofcasing110 and the surroundingformation130.
• Visible also in FIG. 1 is a working[0027]string200. The workingstring200 is a tubular such as drill pipe having a hollow bore therein. The workingstring200 is used to run various tools into thewellbore100 during the completion process, as well as to inject fluids such as cement as needed. In the view of FIG. 1, the workingstring200 is also used to run in a lower string ofcasing140 into thewellbore100.
• The lower string of[0028]casing140 is supported on the workingstring200 by acarrying mechanism150. The carryingmechanism150 may be a threaded connection, a fluid actuated connection, or other known carrying device. In the embodiment of FIG. 1, an expandable collet is used as thecarrying mechanism150. Thecollet150 is landed into aradial profile155 within the lower string ofcasing140 so as to support the lower string ofcasing140. Thecollet150 is hydraulically or mechanically actuated as is known in the art, and supports the lower string ofcasing140 until such time as the lower string ofcasing140 has been expandably set by actuation of theexpander tool300.
• Above the[0029]carrying mechanism150 is aswivel160. Theswivel160 allows the workingstring200 to rotate within thewellbore100 without upsetting the connection between theexpandable tubular140 and the workingstring200. As will be shown, the workingstring200 must rotate within thewellbore100 so that it may rotate theexpander tool300, thereby radially expanding the lower string ofcasing140 or other expandable tubular at the desired depth in thewellbore100. Theswivel160 allows thebody350 of theexpander tool300 to be rotated by the workingtubular200 while thecarrying mechanism150 remains stationary.
• The[0030]expander tool300 is a rotary expander tool. This means that the desired expansion is accomplished by rotating expandedrollers365 against the inner surface of theexpandable tubular140. Preferably, rotation of theexpander tool300 is imparted by rotating the workingstring200. However, rotation may also be imparted by a downhole mud-type motor (not shown).
• FIG. 2 is an exploded view of an[0031]exemplary expander tool300. Theexpander tool300 consists of acylindrical body350 having a plurality ofwindows355 formed therearound. Within eachwindow355 is anexpansion assembly360 which includes aroller365 disposed on anaxle370 which is supported at each end by apiston375. Thepiston375 is optionally retained in thebody350 by a pair ofretention members372 that are held in place byscrews374. Theassembly360 includes apiston surface380 formed opposite thepiston375 which is acted upon by pressurized fluid in thebore390 of theexpander tool300. The pressurized fluid causes theexpansion assembly360 to extend radially outward and into contact with the inner surface of the lower string ofcasing140. With a predetermined amount of fluid pressure acting on thepiston surface380 ofpiston375, the lower string ofcasing140 is expanded past its elastic limits and into plastic deformation.
• The[0032]expander tool300 shown in FIG. 2 is intended to serve only as an example. Various other embodiments of rotary expander tools exist. It is within the scope of the present invention to utilize any type of rotary expander tool to accomplish the methods of the present invention. However, it is preferred that anexpander tool300 having multiple rows ofrollers365 be used, allowing for a greater length of tubular expansion while the tubular140 is under compression.
• Referring again to FIG. 1, the[0033]wellbore100 of FIG. 1 includes acompressive force apparatus400. Thecompressive force apparatus400 is disposed in thewellbore100 above theexpander tool300, and serves to apply a force downward on the top of the lower string ofcasing140. FIG. 3 presents an enlarged sectional view of a hydraulically actuatedram400 as might be used to apply a compressive load onto the lower string ofcasing140 during the expansion process. Theram400 first comprises aninner mandrel420. In the embodiment of FIG. 3, themandrel420 is generally tubular such that it defines ahollow bore422 therein. Themandrel420 has atop end425 which is threadedly connected to the workingstring200. Themandrel420 also has abottom end430 which is in fluid communication with the expander tool300 (shown in FIG. 1). In the embodiment of FIGS. 1 and 3, thebottom end430 is threadedly connected to a make-up joint320, which itself is connected to theexpander tool300. In this manner, themandrel420 creates ahollow bore422, placing theram400 in fluid communication with thebore210 of the workingstring200 and the bore390 (FIG. 2) of theexpander tool300.
• The[0034]ram400 also comprises abody450 surrounding themandrel420. Thebody450 has atop surface412, a bottom surface414, and an inner surface415 therebetween facing themandrel420. Anannular region470 is left between theouter body450 and themandrel420.
• In order to apply the desired downward force against the[0035]expandable tubular140, fluid is injected from the surface into theannulus470. In order to accomplish this injection, at least one through-opening435 is fabricated into themandrel420 of thehydraulic ram400. Fluid can then travel from thehollow bore210 of the workingstring200, through thebore422 defined within themandrel420, and into theannulus470. Theannulus470 is configured such that the cross-sectional area of fluid above the through-opening435 is greater than the cross-sectional area of fluid below the through-opening435.
• In order to hold injected fluid in the[0036]annulus470, it is necessary to seal theannulus470 above and below the through-opening435. In the embodiment of FIG. 3, theannulus470 is sealed by the use of anupper seal ring440 and alower seal ring445. Both theupper seal440 thelower seal445 are disposed circumferentially around thetubular mandrel420. The through-opening435 resides between the upper andlower seals440,445, allowing fluid to be injected under pressure into theannulus470. Pressure injected into theannulus470 acts on the net hydraulic area betweenseals440 and445 to create a downward force. This downward force causes theram400 to apply a force downward on theexpandable tubular140 below.
• Various arrangements may be proffered in order to achieve the desired area differential between the[0037]upper seal440 and thelower seal445. In the arrangement shown in FIG. 3, thebody450 of theram400 is configured to have anouter surface410 and an inner surface415. The inner surface415 is tapered such that the diameter of the inner surface at anupper end412 is greater than the diameter of the inner surface at the bottom414. This creates the desired surface area differential between theseals440 and445 when pressure is injected into the annulus. Theram400 in FIG. 3 includes anoptional shoulder area426 along themandrel420. The seals are circumferentially fitted between themandrel420 and the inner surface415 of thebody450 in order to seal theannulus470 so as to hold injected fluid. Again, this pressure creates a downward force that in turn causes theram400 to apply a force downward on theexpandable tubular140.
• It is shown in FIG. 3 that the[0038]body450 of theram400 is a separate body from themandrel420. This is necessary in order to allow a downward movement of thebody450 relative to themandrel420 when theram400 is actuated. In one aspect, thelower seal ring445 travels with thebody450 during actuation, while theupper seal ring440 is affixed external to themandrel420 and does not travel. With this arrangement, sufficient distance is provided in the design between theupper seal ring440 and thetop end412 of thebody450 to accommodate the stroke of thebody450 downward without losing hydraulic integrity.
• An optional feature for the[0039]hydraulic ram400 in FIG. 3 is the use ofshearable screws460. One or moreshearable screws460 maintain the position of theouter body450 relative to themandrel420 of theram400 during run-in. In this way,shearable screws460 serve to prevent premature actuation of theram400, and also support thebody450 during run-in. At least oneshearable screw460 is optionally run through themandrel420 and thebody450. When additional pressure is injected so as to actuate theram400, thescrews460 are sheared, allowing thebody450 to move downwardly against the lower string ofcasing140.
• In operation of the[0040]compressive force apparatus400, fluid is injected intobore210 of the workingstring200 under pressure. From there, fluid travels into thebore422 of themandrel420 where it encounters the through-opening435. The through-opening435 permits fluid to flow into theannulus470 of theram400, still under pressure. The application of pressure in theannulus470 acts on the net hydraulic area betweenseals440 and445 to create a downward force on the lower string ofcasing140. Because thelower casing string140 is held in place by the carryingmechanism150, a compressive force is applied to thelower casing string140 along the portion designated for expansion.
• It is noted that the embodiment for a[0041]hydraulic ram400 of FIG. 3 is only an example, and is not to scale. The scope of the present invention includes the use of any hydraulic ram which creates a difference in cross-sectional area for receiving an application of hydraulic pressure, thereby accomplishing a movement or relative motion between two parts. Further, the embodiment for acompressive force apparatus400 of FIG. 3 is only an example such that it is within the scope of the present invention to utilize anycompressive force apparatus400 which applies a compressive force onto a portion of expandable tubular, with the force being directed opposite acarrying mechanism150. In addition, the present invention is not limited to the use of a compressive force apparatus which is on top of the expandable tubular. For example, and by way of example only, a compressive force apparatus could be disposed below an expandable tubular, with an upward force being applied therefrom. In such an embodiment (not shown), the portion of tubular to be expanded would be above the compressive force apparatus, and below the carrying mechanism.
• FIG. 4 presents a sectional view of the[0042]wellbore100 of FIG. 1, having the upper string ofcasing110 in place, and showing the lower string ofcasing140 being expanded into frictional contact with the upper string ofcasing110. In this view, a compressive load is being applied to the lower string ofcasing140 by virtue of hydraulic pressure being injected into theram annulus470, as described above. In this view, therollers365 of theexpander tool300 are being activated. In this regard, the same hydraulic pressure which activates thecompressive force apparatus400 is also used to activate therollers365, as described above in connection with FIG. 2.
• In the step demonstrated in FIG. 4, the[0043]expander tool300 is also being rotated. Rotation is accomplished by rotating the workingstring200. In order to rotate theexpander tool300, it is noted that a sleeve must be able to rotate through theram400. In the particularcompressive force apparatus400 shown in FIG. 3, themandrel420 of thehydraulic ram400 serves as the sleeve. This means that the workingstring200 rotates themandrel420 of thehydraulic ram400, which in turn rotates theexpander tool300. Thecompressive force apparatus400 is designed so that themandrel420 is able to rotate within the upper440 and lower445 seal rings. Rotation of the workingstring200 also assists in shearing thescrews460.
• During the expansion process, fluid is circulated from the surface and into the[0044]wellbore100 through the workingstring200. Abore390, shown in FIG. 2, runs through theexpander tool300, placing the workingstring200 and theexpander tool300 in fluid communication. Afluid outlet395 is provided at the lower end of theexpander tool300. In the arrangement shown in FIGS. 1 and 2, a tubular member serves as thefluid outlet395.
• By actuation of the[0045]expander tool300 against the inner surface of the lower string ofcasing140, a portion of the lower string ofcasing140 is expanded into the upper string ofcasing110. In this manner, the top portion of the lower string of casing140U is placed in essentially sealed fluid communication with the upper string ofcasing110. In order to provide a more complete expansion job, the workingstring200 is optionally raised from the surface after the initial expansion of the lower string of casing140U has taken place. Alternatively, an apparatus (not shown) may be placed downhole which translates theexpander tool300 within thewellbore100 without pulling the workingstring200. Hydraulic pressure continues to be provided to theexpander tool300 while the workingstring200 is raised.
• In order to raise the[0046]expander tool300 during expansion, the connection between the carryingmechanism150 and the lower string ofcasing140 must be released. In the arrangement shown in FIG. 4, thecollet150 has been released from theprofile155. Such release mechanisms are known in the art.
• FIG. 5 is a sectional view of the wellbore of FIG. 4, showing the[0047]upper portion140U of expandable tubular140 in complete, frictional engagement with the upper string ofcasing110. The workingstring200 and associated tools, e.g.,expander tool300 andhydraulic ram400, are being removed from thewellbore100. At this stage in the expansion operation, theexpander tool300 has been deactivated. In this regard, fluid pressure supplied to thepistons375 is reduced or released, allowing thepistons375 to return to therecesses355 within thecentral body350 of thetool300. Theexpander tool300 can then be withdrawn from thewellbore100 by pulling the workingstring200.
• It is noted that pulling the working[0048]string200 also produces the removal of thehydraulic ram400 from thewellbore100. While theshearable screws470 have been sheared from thehydraulic ram400, thehydraulic ram400 will be raised from thewellbore100 when theexpander tool300 is raised. In this regard, theexpander tool300 will catch the bottom of thehydraulic ram400 on the way out of thehole100.
• FIG. 6 is a sectional view of the wellbore of FIG. 5, illustrating the[0049]upper portion140U of thelower casing string140 expanded into theupper casing string110 after theexpander tool300 and workingstring200 have been removed. This view more fully illustrates the frictional engagement between the upper110 and lower140 strings of casing. FIG. 6 demonstrates that the lower string ofcasing140 has also been cemented into thewellbore100. Cement is shown in theannulus500 behind the lower string ofcasing140. In the view of FIG. 6,optional slip195 and sealing190 members are shown disposed around the lower string ofcasing140.
• First, a sealing[0050]ring190 is shown disposed on the outer surface of the lower string ofcasing140. In the preferred embodiment, the sealingring190 is an elastomeric member circumferentially fitted onto the outer surface of thecasing140. However, non-elastomeric sealing materials may also be used. The sealingring190 is designed to seal anannular area500 formed between the outer surface of the lower string ofcasing140 and the inner surface of the upper string ofcasing110 upon expansion of thelower string140 into theupper string110.
• Also positioned on the outer surface of the lower string of[0051]casing140 is at least oneslip member195. In the view of FIG. 6, theslip member195 defines a pair of rings having grip surfaces formed thereon for engaging the inner surface of the upper string ofcasing110 when the lower string ofcasing140 is expanded. In FIG. 6, oneslip ring195 is disposed above the sealingring190, and oneslip ring195 is disposed below the sealingring190. The grip surface includes teeth formed on eachslip ring195. However, the slips could be of any shape and the grip surfaces could include any number of geometric shapes, including button-like inserts (not shown) made of high carbon material.
• It should again be noted that the[0052]separate slip195 and sealing190 members are optional. Further, other arrangements for slip and sealing members could be employed. For example, an elastomeric sealing material could be disposed in a matrix of grooves (not shown) within the outer surface of theupper portion140U of the lower string ofcasing140. Carbide buttons (not shown) or other gripping members could be placed between the grooves.
• FIG. 7 is a cross-sectional view of a wellbore illustrating an alternate means for assisting in the expansion of a tubular. Visible in this view is a barrel-shaped configuration for a portion of the expandable tubular where expansion is to begin. The barrel-shaped portion is identified at[0053]140B. The barrel-shapedportion140B of the lower string ofcasing140 is created by pre-stressing the tubular140 before it is run into thehole100. Pre-stressing the tubular140 causes the tubular140 to more readily buckle outwardly upon application of an expansive force from within theexpandable tubular140, thus aiding theexpander rollers365. This, in turn, further alleviates the thinning effect which would otherwise occur on the flanks of theexpander members365. The ultimate benefit is a stronger transition zone in thecasing140U that will carry more weight axially and also enjoy stronger resistance to collapse.
• The view of FIG. 7 demonstrates the use of both a[0054]compressive force apparatus400 and a barrel-shape pre-formed in theexpandable tubular140B. However, it will be appreciated that the use of acompressive force apparatus400 is optional where a pre-stressing or other bias has been applied to theexpandable tubular140B. Further, it is within the spirit and scope of the present invention to utilize other biasing means for more easily expanding a tubular. An example would be a biasing feature or structure machined into the expandable tubular.
• In operation, the method of the present invention in one embodiment is useful in a[0055]wellbore100 having a first string of cementedcasing110. Thewellbore100 is drilled to a new depth so that a second string of casing, or liner, may be set. Thereafter, the drill string and drill bit are removed, and arotary expander tool300 is run into thewellbore100 on a workingstring200. A carryingmechanism150 is utilized for carrying the second string ofcasing140 into thehole100 on the workingstring200. The second string ofcasing140 is then positioned within thewellbore100 so that theupper portion140U of the second string ofcasing140 overlaps with the bottom portion of the first string ofcasing110.
• Along with the[0056]expander tool300, acompressive force apparatus400 is run into thewellbore100. In the preferred embodiment of the method of the present invention, thecompressive force apparatus400 defines a hydraulically actuated ram. Theram400 is positioned downhole over the top of the lower string ofcasing140. Fluid is then injected into the workingstring200 from the surface. Fluid enters theannulus470 of theram400, thereby causing a downward force to be applied onto the top of the lower string ofcasing140. Compression is thereby achieved between the top of the lower string ofcasing140 and the point of connection between the lower string ofcasing140 and thecarrying mechanism150.
• The application of hydraulic pressure into the[0057]wellbore100 also activates therotary expander tool300. Therotary expander tool300 applies an outward force from the inner surface of the lower string ofcasing140, bringing the outer surface of the lower string ofcasing140 into frictional engagement with the inner surface of the first, or upper string ofcasing110. Theexpander tool300 may optionally be raised within thewellbore100 during the expansion process so as to obtain expansion of the lower string ofcasing140 along a desired length. This step would require release of the connection between the carryingmechanism150 and the tubular140 being expanded. Alternatively,roller assemblies300 could be positioned along the entire length of desired expansion.
• After expansion is completed, the working[0058]string200 is removed from thewellbore100 along with theexpander tool300 and thecompressive force apparatus400. The result is in an effective hanging of the lower string ofcasing140 upon the upper string ofcasing110 within thewellbore100. Thus, the method of the present invention enables a lower string ofcasing140 or other expandable tubular to be more effectively hung onto an upper string ofcasing110 by compressively expanding thelower string140 into an overlapping portion of theupper string110.
• It is noted that a[0059]shoulder480 is needed in order to pull theouter body450 of theram400 from the hole. This is because theouter body450 defines a separate body from themandrel420 of theram400. In the embodiment shown in FIG. 3, anenlarged collar480 is used as the shoulder for lifting theouter body450 from thewellbore100. Thecollar480 comes into contact with the bottom end or base414 of theouter body450 when theexpander tool300 is pulled.
• While an[0060]enlarged collar480 is used as the shoulder in the preferred embodiment, it is acceptable to utilize other “no-go” arrangements. For example, thebody350 of theexpander tool300 itself could serve as a shoulder for lifting theouter body450. Alternatively, a shoulder could be added to a make-up joint320 (arrangement not shown).
• The preferred embodiment for the method of the present invention involves the expansion of a lower string of casing into an overlapping portion of an upper string of casing. However, it is within the scope of this invention to utilize compressive force to aid in the expansion of any expandable tubular. Other types of expandable tubulars include, but are not limited to, expandable sand screens, expandable seats for packers or whipstocks or for other tools, and expandable production tubing.[0061]
• While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.[0062]

Claims (19)

1. A method for expanding a first tubular into a second tubular in a wellbore, comprising the steps of:

positioning the first tubular within a wellbore;

running the second tubular to a selected depth within the wellbore such that at least a portion of the second tubular overlaps with the first tubular;

applying a compressive force to at least a portion of the second tubular; and

expanding a portion of the second tubular which is in compression so that the outer surface of the expanded portion of the second tubular is in frictional contact with the inner surface of the first tubular.

2. The method for expanding a first tubular into a second tubular ofclaim 1, wherein the step of running the second tubular to a selected depth within the wellbore is accomplished by connecting the second tubular to a carrying mechanism on a working string.

3. The method for expanding a first tubular into a second tubular ofclaim 2, wherein the step of applying a compressive force to at least a portion of the second tubular is accomplished by positioning a compressive force apparatus on top of the second tubular, and activating the compressive force apparatus so as to impart a downward force from the top of the second tubular.

4. The method for expanding a first tubular into a second tubular ofclaim 3, wherein

said compressive force apparatus is a hydraulically actuated ram; and

said step of activating the compressive force apparatus so as to impart a downward force on the top of the second tubular is done by injecting fluid into an annular region within said hydraulically actuated ram.

5. The method for expanding a first tubular into a second tubular ofclaim 3, wherein the first tubular and the second tubular each define a string of casing.

6. The method for expanding a first tubular into a second tubular ofclaim 5, wherein

said carrying mechanism is a collet; and

said step of expanding a portion of the second tubular is accomplished by actuating a rotary expander tool having a plurality of rollers, said rotary expander tool being activated by hydraulic pressure.

7. The method for expanding a first tubular into a second tubular ofclaim 6, further comprising the step of placing a swivel between said collet and said rotary expander tool such that rotation of said rotary expander tool does not interfere with the connection between said collet and the second tubular.

8. The method for expanding a first tubular into a second tubular ofclaim 6, further comprising the steps of:

releasing said collet from said second tubular after expansion of the second tubular has begun; and

raising said expander tool within the wellbore so as to further expand the second tubular along a desired length.

9. The method for expanding a first tubular into a second tubular ofclaim 3, further comprising the step of biasing at least a portion of the second tubular to be expanded before said step of running the second tubular to a selected depth within the wellbore, so as to bias said portion of the second tubular to buckle outwardly upon said step of expanding a portion of the second tubular.

10. The method for expanding a first tubular into a second tubular ofclaim 9, wherein the step of biasing at least a portion of the second tubular to be expanded is accomplished by pre-stressing the portion of the second tubular to be expanded outwardly.

11. A method for expanding a first tubular into a second tubular in a wellbore, the first tubular and the second tubular each having a top portion and a bottom portion, comprising the steps of:

positioning the first tubular within a wellbore;

connecting the second tubular to a working string by a releasable carrying mechanism;

connecting a rotary expander tool to said working string above said carrying mechanism;

connecting a swivel to said working string between said carrying mechanism and said rotary expander tool;

connecting a compressive force apparatus to said working string above said rotary expander tool, such that said compressive force apparatus is disposed on the top of the second tubular;

running the second tubular to a selected depth within the wellbore on said working string such that the top portion of the second tubular overlaps with the bottom portion of the first tubular;

activating said compressive force apparatus to apply a compressive force to the top portion of the second tubular between the top of the second tubular and the point of connection of the second tubular with the releasable carrying mechanism; and

activating said rotary expander tool so as to expand at least a portion of the top portion of the second tubular into frictional engagement with the inner surface of the first tubular.

12. The method for expanding a first tubular into a second tubular ofclaim 11, wherein the first tubular and the second tubular each define a string of casing.

13. The method for expanding a first tubular into a second tubular ofclaim 12, wherein said compressive force apparatus is a hydraulically actuated ram comprising:

a tubular mandrel having a top end, a bottom end, and a bore therein, said hollow bore being in fluid communication with said working string;

an outer body having a top end, a bottom end, and an inner surface therebetween,;

a through-opening within said mandrel;

an annular region between said mandrel and said inner surface of said body for receiving fluid from said through-opening in said mandrel, the annular region being configured such that the cross-sectional area of fluid above said through-opening is greater than the cross-sectional area of fluid below said through-opening;

an upper seal in said annular region, said upper seal being disposed between said mandrel and said inner surface of said body above said through-opening; and

a lower seal in said annular region, said lower seal being disposed between said mandrel and said inner surface of said body below said through-opening, thereby creating a fluidly sealed annular region around said through-opening.

14. The method for expanding a first tubular into a second tubular ofclaim 13, wherein

the top end of the mandrel is threadedly connected to the working string; and

the bottom end of the mandrel is in fluid communication with the expander tool.

15. The method for expanding a first tubular into a second tubular ofclaim 14, wherein said step of activating said compressive force apparatus and said step of activating said rotary expander tool are accomplished by injecting hydraulic fluid under pressure through said working string and into said fluidly sealed annular region.

16. The method for expanding a first tubular into a second tubular ofclaim 15, wherein said carrying mechanism is a collet.

17. The method for expanding a first tubular into a second tubular ofclaim 16, further comprising the steps of:

releasing said collet from said second tubular after expansion of the second tubular has begun; and

raising said rotary expander tool within the wellbore so as to expand the second tubular along a desired length.

18. The method for expanding a first tubular into a second tubular ofclaim 17, further comprising the step of biasing at least a portion of the second tubular to be expanded before said step of running the second tubular to a selected depth within the wellbore, so as to bias said portion of the second tubular to buckle outwardly upon said step of activating said rotary expander tool.

19. The method for expanding a first tubular into a second tubular ofclaim 18, wherein the step of biasing at least a portion of the second tubular to be expanded is accomplished by pre-stressing the portion of the second tubular to be expanded outwardly.

Images