The present system and method comprises an expandable device for use in wellbores. In one embodiment, the present device comprises a plurality of slots disposed within the device. The slots define expansion compensation portions, wherein the compensation portions facilitate radial expansion of the device while concurrently maintaining essentially constant the axial length of the device. The present technique also comprises a method of forming the device in accordance therewith.

CROSS REFERENCE TO RELATED APPLICATIONS 
   The following is based on and claims priority to provisional application No. 60/385,778 filed Aug. 6, 2002. 


   FIELD OF THE INVENTION 
   The present technique relates to the field of expandable devices and methods. More particularly, the technique comprises an expandable device and a method related to an expandable device that has reduced axial shrinkage during radial deformation or expansion thereof. 
   BACKGROUND OF THE INVENTION 
   In the production of sub-terrain fluids, such as oils or natural gas, a variety of expandable devices have been used to cultivate wellbore environments. For example, generally tubular devices, such as expandable liners, expandable sandscreens, well linings and well patches have been employed. These devices may be expandable devices which, under the proper stimuli, transition from a collapsed (small diameter) configuration to an expanded (large diameter) configuration. In many instances, expandable devices comprise a plurality of longitudinal slots or openings that increase in size as the device is expanded (U.S. Pat. Nos. 5,366,012 and 5,667,011). These openings, if so desired, may be configured to permit the flow of desirable production fluids into the interior of the wellbore while simultaneously preventing the ingress of contaminants, such as sand. 
   Expandable devices are typically deployed downhole into the wellbore, while in their respective collapsed configurations. In other words, the diameter of the collapsed expandable device is less than that of the wellbore and, as such, the expandable device feeds easily into the wellbore. Once the expandable device is lowered to a desired location within the wellbore, a radial expansion force is applied to drive the device to an expanded configuration. Accordingly, the device may better conform to the interior surface of the wellbore. 
   If so desired, expandable devices may be coupled to form a conduit that extends for great distances below the Earth's surface. Indeed, wellbores may extend thousands of feet below the Earth's surface to reach production fluids disposed in subterranean geological formations commonly know as “reservoirs”. 
   In many traditional systems (U.S. Pat. Nos. 5,366,012 and 5,667,011), however, an increase in the radial dimension of the device induces a decrease in the axial dimension thereof. In other words, as the device diameter increases, the device length decreases. Accordingly, it may be more difficult to properly position the device into the wellbore. Moreover, a change in axial length may lead to separation or damage of already coupled devices. 
   The present invention is directed to overcoming, or at least reducing the effects of one or more of the problems set forth above, and can be useful in other applications as well. 
   SUMMARY OF THE INVENTION 
   In one embodiment of the present technique, an expandable device comprises a tubular having a plurality of slots therein. The tubular is configured to expand from a first diameter to a second diameter such that the axial length of the tubular remains substantially constant. 
   According to an alternate embodiment of the present technique, a device comprising a device segment having a plurality of slots disposed therein is provided. In this alternate embodiment, the slots define first and second members coupled to one another, wherein at least one of the first and second members is adapted to substantially retard axial contraction of the device upon radial expansion of the device. 
   According to yet another embodiment of the present technique, a system for producing wellbore fluids is provided. In this embodiment, the system comprises a wellbore, a device, and an expansion mechanism for expanding the device from a collapsed configuration to an expanded configuration. Moreover, the device comprises an expansion compensation portion, wherein the expansion compensation portion is adapted to retard axial contraction of the device upon radial expansion thereof. 
   According to yet another embodiment of the present technique, a method for deploying an expandable device into a wellbore is provided. The method comprises inserting a device, the device being in a collapsed configuration, into a wellbore. The method further comprises expanding the device to an expanded configuration such that the axial length of the device remains substantially constant. 
   In another embodiment of the present technique, a method for forming an expandable device is provided. The method comprises cutting a pattern of slots into a segment of the device, wherein each pattern of slots comprises an axial contraction compensation portion. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and; 
       FIG. 1  is a depiction of a wellbore having a plurality of exemplary expandable devices disposed therein; 
       FIG. 2  is a depiction of a portion of an embodiment of an expandable device; 
       FIG. 3A  is a depiction of a portion of an embodiment of an expandable device in a collapsed configuration; 
       FIG. 3B  illustrates the device of  FIG. 3A  in an expanded configuration; 
       FIG. 4A  is a depiction of a portion of another embodiment of an expandable device in a collapsed configuration; 
       FIG. 4B  illustrates the device of  FIG. 4A  in an expanded configuration; 
       FIG. 5  is an illustration of an embodiment of a cell of an expandable device, the cell being in the collapsed configuration; 
       FIG. 6A  is a depiction of a portion of another embodiment of an expandable device in a collapsed configuration; 
       FIG. 6B  illustrates the device of  FIG. 6A  in an expanded configuration; 
       FIG. 7  is a flattened elevational view of an embodiment of an expandable device having a certain pattern of slots; 
       FIG. 8  is a cross-sectional view of an expandable device having a cutout portion; and 
       FIG. 9  is a depiction of a wellbore having an embodiment of an expandable device disposed therein with an expansion mechanism for expanding the device. 
   


   DETAILED DESCRIPTION 
   Referring generally to  FIG. 1 , an exemplary wellbore environment is illustrated. For example,  FIG. 1  illustrates a wellbore  20  having at least one lateral branch section  22 . The wellbore  20  may be drilled into the surface of the Earth to facilitate removal of production fluids (i.e. natural gas, oil, etc.) therefrom. In operation, production fluids may enter from the “reservoir” into the wellbore  20 . Subsequently, by employing traditional production methods well known to the skilled artisan, the production fluids may be retrieved to the Earth's surface. 
   Disposed along the interior surface of the wellbore  20  may be a casing  24 . The casing  24  may provide structural integrity to the wellbore  20  and can be cemented into location if so desired. Indeed, the casing  24  may extend for thousands of feet into the wellbore  20  as well as into the lateral branch sections  22 . 
   At least one expandable device  26  also is disposed within the wellbore  20 . As further discussed below, devices  26  may comprise, casing patches, expandable packers, expandable hangers, expandable liners, expandable casings  24 , expandable sandscreens or expandable control line conduits (i.e. conduits for fiber optic lines, electric lines, hydraulic lines, etc.). As is also further discussed below, devices  26  may be inserted into the wellbore in a collapsed configuration and subsequently expanded. By inserting devices  26  into the wellbore  20  in a collapsed state, a number of advantages may be achieved over traditional systems. For example, a device  26  in the collapsed state may have a diameter less than that of the wellbore it is to be inserted into, and, as such, require less effort for downhole insertion. 
   Referring next to  FIG. 2 , a section  28  of an expandable device  26  ( FIG. 1 ) is illustrated. The device  26  comprises a wall  30  having a plurality of slots  32  disposed therein. Although the embodiment is illustrated as having slots  32  disposed in the wellbore, the present technique may also be employed with thinned or weakened areas in lieu of the slots  32 . In this embodiment, slots  32  define thick and thin struts  34  and  36 , respectively. The thick and thin struts  34  and  36  may include various expansion compensation portions  38 , the compensation portions  38  being adapted to prevent axial contraction of the device  26  upon radial expansion thereof. 
   For example, the compensation portions  38  may comprise spring segments  40  that facilitate axial expansion of the appropriate strut members  36 . Thus, during radial expansion of the device  26 , the spring segment  40  may flex, thereby allowing the strut member  36  upon which it is integrated, to contract or expand as necessary. In other words, the spring segment  40  changes length axially during device expansion, thereby enabling the device  26 , as a whole, to radially expand without substantial axial contraction thereof. In some embodiments, the spring segment  40  may undergo both elastic deformation as well as plastic deformation. 
   Under expansion loads, relatively thick struts  34  remain essentially undeformed and, as such, maintain the overall axial length of the device  26 . Contemporaneously, however, the expansion loads applied to the thin members  36  induce axial contraction lengthening thereof, thereby facilitating radial expansion of the device  26 . Moreover, the spring segments  40  may also provide additional flexibility to the device  26  thereby reducing the expansion forces necessary to drive device  26  to its expanded configuration. 
   Additionally, compensation portions  38  may comprise rotational segments  42  disposed along respective strut members  36 . Rotational segments  42  also substantially reduce axial contraction of the device  26  (FIG.  1 ), as a whole, upon radial expansion thereof. Indeed, during expansion, the exemplary rotational segments  42 , as well as the relatively thin strut  36  within which it is disposed, tend to rotate whereas the relatively thick struts  34  retain their original configuration. This torsional deformation of the thin struts  36 , being either plastic or elastic, allows the device  26  to radially expand while the rigid thick struts  34  substantially maintain the original axial length of device  26 . The rotational segments  42  may have tapering portions, rounded portions or other variations in the thickness of the strut  36  to optimize the properties of the rotational segments  42 . 
   Disposed between adjacent, relatively, thick and thin struts  34  and  36  may be hinge portions  44 . In the exemplary embodiment, hinge portions  44  facilitate the pivotal movement of the strut members  34  and  36  with respect to one another. The hinge portions  44  may be thinned sections of wall  30  disposed at the intersection of the respective ends of the struts  34  and  36 . The thinner hinge portions  44  reduce the overall expansion force required to drive the exemplary device from a collapsed to an expanded configuration. 
   Various features of the expandable device  26 , such as the strut members  34  and  36 , compensation portions  38  as well as the corresponding slots  32  may be formed by a number of processes. For example, these features may be formed by targeting a high-pressure water jet stream against the stock material from which the device  26  is to be formed. The water pressure carves out desired features on to the device. In a similar vein, these features may be carved by laser-jet cutting the stock material. Additionally, the features may be formed by a stamping process. In this process, the flat stock material is placed into a press which then stamps the features into the material. Once stamped, the material may be rolled into a rounded or tubular form. To ensure structural integrity of the stamped material, the features may be at least as wide as the thickness of the material being stamped. 
   Referring next to  FIGS. 3A and 3B , an alternate embodiment of the present technique is illustrated. Particularly,  FIGS. 3A and 3B  illustrate one embodiment of section  28  of device  26  in the collapsed configuration and expanded configuration respectively. Section  28  comprises compensation portions  38 , such as spring segments  40  and rotational segments  42 . Again, as the device  26  is taken from the collapsed to expanded configuration, the expansion forces may induce deformation of the thin strut  36 . However, the relatively thick strut  34 , because of its size, resists deformation. Accordingly, the thin struts  36  facilitate radial expansion of the device while the thick struts  34 , concurrently, maintain the axial length of the device  26 . 
   Referring next to  FIGS. 4A and 4B , another embodiment of the present technique is illustrated. In the collapsed state, as illustrated in  FIG. 4A , section  28  comprises thick and thin struts  34  and  36 , respectively, traversed by a linking member  46 . The linking member is connected to the respective struts  34  and  36  by hinge portions  44 . The linking member  46 , in conjunction with the thin and thick struts  34  and  36 , respectively may define parallelogramic slots  32 . 
   During radial expansion of device  26  to the expanded configuration illustrated in  FIG. 4B , the linking member  46  pivots about hinge portions  44 . The linking members  46  may pivot such that the thick and thin struts  34  and  36  remain parallel to one another. Additionally, similar to the above embodiments, compensation portions  38  facilitate radial expansion of the device while concurrently maintaining the overall length of the device. In the exemplary embodiment, the spring segments  40  may deform thereby facilitating radial expansion of the device without substantially affecting axial length. Moreover, the linking members  46  may be configured to elastically or plastically deform, thereby assisting in the radial expansion of the device  26 . 
   Referring next to  FIG. 5 , an expandable cell  48  of an expansion section  28  in a collapsed configuration is illustrated. In this embodiment, a relatively thin bending connector  50  traverses adjacent thick struts  34 . The bending connector  50  may comprise folding portions  52  and spring segments  40 . During radial expansion, the thick struts  34  distance themselves from one another, and resultantly, the folding portions  52  begin to unfold. As the radial expansion continues, bending connector  50  may undergo axial deformation. Indeed, the spring segments  40  of the bending connector  50  may undergo elastic or plastic deformation to facilitate the radial expansion of the device  26  without axial contraction thereof. The bending connector  50  maintains the thick struts  34  generally parallel to one another during the expansion process. 
   Referring next to  FIGS. 6A and 6B , another embodiment of the present device is illustrated in collapsed and expanded configurations, respectively. In this embodiment, section  28  comprises a series of linking members  46  and thin struts  36  which, in combination, define three separate slot shapes  32   a ,  32   b , and  32   c . The linking members  46  as well as the thin struts  36  may comprise spring portions as well as rotation portions, e.g. spring portions  40  and rotation portions  42 . Spring portions  40  and rotation portions  42  serve as expansion compensators radial expansion of the device to prevent shortening the original axial length of device  26 . Referring to  FIG. 7 , the slot pattern of  FIGS. 6A and 6B  is illustrated as a flat sheet. Advantageously, tubulars may be formed from flat sheets which are subsequently bent into a cylindrical shape. 
   Returning to  FIG. 1 , the present technique may be employed in many types of devices  26  employable within a wellbore  20 . For example, the device  26  may be a casing patch  54 . If, for illustrative purposes, a hole were to develop in the casing  24 , the structural integrity of the casing  24  may be affected. Accordingly, a casing patch  54  may be deployed to the location of the hole in the collapsed configuration. Subsequently, the casing patch  54  may be expanded to secure the casing patch  54  to the damaged portion of the original casing  24 . The device may also comprise an expandable liner  56  for the multilateral junctions. Again, the liner  56  may be deployed to the desired location and subsequently expanded for securing at such location. The device  26  may also comprise an expandable packer  58  deployed, for example, to isolate portions of a wellbore  20 . In operation, the packer  58 , similar to other expandable devices described herein, may be deployed to a desired location and subsequently expanded. Yet another embodiment of device  26  is an expandable sand-screen  60 . Sand-screens  60  may be placed into the wellbore  20  to prevent the ingress of sand from the interior wellbore surface while concurrently permitting the ingress of desirable production fluids. Lastly, although not exhaustively, the device  26  may comprise an expandable hanger  62 . In operation, the expandable hanger  62  facilities, for example, the coupling of casing or lining segments together. Indeed, the hanger  62  may allow casings or linings to extend for hundreds of feet into the wellbore. Again, each of the exemplary devices  26  discussed above may be formed, at least in part, of the expandable devices of the present technique. 
   Referring to  FIG. 8 , a cross-sectional view of an expandable device  26  having a cutout portion  64  is illustrated. The cutout portion  64  may be employed as a passageway for the routing of control lines  66  therethrough. Additionally, intelligent completions equipment, monitoring devices, fiber optic lines and other equipment may be positioned in the cutout portion  64 . As illustrated, cutout portion  64  lies in a generally axial direction along the exterior of device  26 , although the cutout can be formed along an interior surface or entirely within the wall of device  26 . 
   Referring to  FIG. 9 , a cone  68  is illustrated as expanding the device  26 . A variety of expansion devices may be employed and cone  68  is just one option. Once the expandable device  26  has been placed at the appropriate position in the wellbore, cone  68  is then pulled or pushed therethrough. A tapered end  70  of cone  68  may easily be fed into the device  26  when in its collapsed configuration. As the cone  68  progresses further, the widening diameter of the cone abuts against the interior surface of the device and imparts the necessary radial forces for expansion. 
   While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Indeed, the present technique may be employed in any number of oilfield applications such as umbilical or conduit repairs for example.