Abstract:
A well completion system for creating a seal between a production tubing ( 30 ) and a well casing ( 34 ) positioned within a wellbore ( 32 ) comprises a production packer ( 46 ) that includes a section of the production tubing ( 30 ) and at least one seal element ( 60 ). The production tubing ( 30 ) is then positioned within the well casing ( 34 ) that lines the wellbore ( 32 ). An expander member ( 56 ) that is positioned within the production tubing ( 30 ) then travels longitudinally through the production packer ( 46 ) to expand the section of the production tubing ( 30 ) downhole that includes the seal element ( 60 ). This expansion creates a sealing and gripping relationship between the production tubing ( 30 ) and the well casing ( 34 ).

Description:
TECHNICAL FIELD OF THE INVENTION 
   This invention relates, in general, to completing a well that traverses a hydrocarbon bearing subterranean formation and, in particular, to a system and method for creating a fluid seal between production tubing and well casing by expanding a section of the production tubing having seal elements positioned therearound. 
   BACKGROUND OF THE INVENTION 
   Without limiting the scope of the present invention, its background will be described with reference to producing fluid from a subterranean formation, as an example. 
   After drilling each of the sections of a subterranean wellbore, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within each section of the wellbore. This casing string is used to increase the integrity of the wellbore by preventing the wall of the hole from caving in. In addition, the casing string prevents movement of fluids from one formation to another formation. Conventionally, each section of the casing string is cemented within the wellbore before the next section of the wellbore is drilled. Accordingly, each subsequent section of the wellbore must have a diameter that is less than the previous section. 
   For example, a first section of the wellbore may receive a conductor casing string having a 20-inch diameter. The next several sections of the wellbore may receive intermediate casing strings having 16-inch, 13⅜-inch and 9⅝-inch diameters, respectively. The final sections of the wellbore may receive production casing strings having 7-inch and 4½-inch diameters, respectively. Each of the casing strings may be hung from a casing head near the surface. Alternatively, some of the casing strings may be in the form of liner strings that extend from near the setting depth of previous section of casing. In this case, the liner string will be suspended from the previous section of casing on a liner hanger. 
   Once this well construction process is finished, the completion process may begin. The completion process comprises numerous steps including creating hydraulic openings or perforations through the production casing string, the cement and a short distance into the desired formation or formations so that production fluids may enter the interior of the wellbore. In addition, the completion process may involve formation stimulation to enhance production, gravel packing to prevent sand production and the like. The completion process also includes installing a production tubing string within the well that extends from the surface to the production interval or intervals. Unlike the casing strings that form a part of the wellbore itself, the production tubing string is used to produce the well by providing the conduit for formation fluids to travel from the formation depth to the surface. 
   Typically, a production packer is run into the well on the production tubing string. The purpose of the packer is to support production tubing and other completion equipment, such as a screen adjacent to a producing formation, and to seal the annulus between the outside of the production tubing and the inside of the well casing to block movement of fluids through the annulus past the packer location. Conventionally, the packer is provided with anchor slips having opposed camming surfaces which cooperate with complementary opposed wedging surfaces, whereby the anchor slips are radially extendible into gripping engagement against the interior of the well casing in response to relative axial movement of the wedging surfaces. 
   The packer also carries annular seal elements which are expandable radially into sealing engagement against the interior of the well casing in response to axial compression forces. The longitudinal movement of the packer components required to set the anchor slips and the sealing elements may be produced either hydraulically or mechanically. 
   After the packer has been set and sealed against the well casing, this sealing engagement will typically remain even upon removal of the hydraulic or mechanical setting force. In fact, it is essential that the packer remain locked in its set and sealed configuration such that it can withstand hydraulic pressures applied externally or internally from the formation and/or manipulation of the production tubing string and service tools without unsetting or interrupting the seal. 
   It has been found, however, that to provide the required sealing and gripping capabilities, conventional packers have become quite complex. In addition, it has been found that due to the complexity of conventional packers, the cost of conventional packers is quite high. Further, it has been found that even with the complexity of conventional packers, some conventional packers fail to provide the necessary sealing and/or gripping capability after installation. 
   A need has therefore arisen for a system and method for creating a fluid seal between production tubing and well casing that does not require a complex conventional packer. A need has also arisen for such a system and method that are capable of reducing the cost typically associated with manufacturing a conventional packer. Further, a need has arisen for such a system and method that provide for improved sealing and gripping capabilities upon installation. 
   SUMMARY OF THE INVENTION 
   The present invention disclosed herein comprises a system and method for creating a fluid seal between production tubing and well casing that does not require a complex conventional packer. The system and method of the present invention are capable of reducing the cost typically associated with manufacturing a conventional packer. In addition, the system and method of the present invention provide for improved sealing and gripping capabilities upon installation. 
   The well completion system for creating a seal between a production tubing and a well casing of the present invention comprises a production packer including a section of the production tubing and at least one seal element and an expander member positioned within the production tubing that travels longitudinally through the production packer to expand the section of the production tubing downhole, thereby creating the seal between the production tubing and the well casing. The expander member may travel longitudinally within the production packer from an uphole location to a downhole location or from a downhole location to an uphole location. 
   The expander member may be urged to travel longitudinally within the production packer by pressurizing at least a portion of the production tubing. Alternatively, coiled tubing may be coupled to the expander member. In this case, the expander member may be urged to travel longitudinally within the production packer by pressurizing the coiled tubing and at least a portion of the production tubing, by pulling the coiled tubing or both. Prior to pressurizing the portion of the production tubing a plug may be set within the production tubing to seal the pressure within the production tubing that acts on the expander member. Alternatively, the expander member may be urged to travel longitudinally within the production packer by pushing on the coiled tubing to compress the expander member then pressurizing the coiled tubing and an interior section of the expander member to urge the expander member to travel longitudinally within the production packer. 
   Following the expansion of the production packer and during the same trip downhole, a treatment fluid may be pumped downhole and through a cross-over assembly operably associated with the expander member such that the treatment fluid is delivered into an annulus between the production tubing and the well casing downhole of the production packer. The treatment preformed may be a fracture treatment, a gravel pack, a frac pack or the like. Following the treatment process, the expander member may be retrieved to the surface by decoupling a work string, carrying the expander member and the cross-over assembly, from the production tubing that is now fixed within the casing. 
   Broadly stated, the method of the present invention involves lining the wellbore with the well casing, disposing a production packer including a section of the production tubing and at least one seal element within the well casing and setting the production packer downhole by radially expanding the section of the production tubing, thereby creating the seal between the production tubing and the well casing. 
   The method of the present invention may also involve lining the wellbore with the well casing, positioning an expander member and a plug within the production tubing, disposing a production packer including a section of the production tubing and at least one seal element within the well casing, coupling a coiled tubing to the expander member, installing the plug within the production tubing, pressurizing the coiled tubing and at least a portion of the production tubing between the plug and the expander member, urging the expander member to travel longitudinally within the production packer, creating the seal between the production tubing and the well casing, retrieving the coiled tubing and the expander member uphole and retrieving the plug uphole. 
   Likewise, the method of the present invention may involve disposing a production packer including a section of a production tubing and at least one seal element within a well casing, setting the production packer downhole by radially expanding the section of the production tubing to create a seal between the production tubing and the well casing and pumping a treatment fluid through a cross-over assembly into an annulus between the production tubing and the well casing downhole of the production packer. 
   Once an expandable production packer of the present invention is installed, it may become necessary to remove the expandable production packer of the present invention from its sealing relationship with the well casing. One method for releasing an expandable production packer of the present invention involves positioning a release member within the expandable production packer such that first and second end sections of the release member are on opposite sides of the seal element of the expandable production packer and operating the release member such that the diameter of the seal element is reduced, thereby releasing the seal element from contact with the well casing. 
   This reduction may be achieved by elongating the expandable production packer, by generating a radially inwardly acting collapse force due to a differential pressure between the interior and the exterior of the expandable production packer or both. In those embodiments wherein the collapse force is utilized, this operation may be enhanced by weakening the expandable production packer behind the seal element. This weakening process may be achieved chemically, mechanically, thermally, explosively or the like. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
       FIG. 1  is a schematic illustration of an offshore oil and gas platform installing an expandable production packer according to the present invention; 
       FIG. 2  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string; 
       FIG. 3  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string after installation of a plug; 
       FIG. 4  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string prior to expansion; 
       FIG. 5  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string during expansion; 
       FIG. 6  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string prior to expansion; 
       FIG. 7  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string during expansion; 
       FIGS. 8A-8B  are a half sectional views of an expander member for use in expanding the expandable production packer according to the present invention in its contacted and expanded positions, respectively; 
       FIG. 9  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string prior to expansion; 
       FIG. 10  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string during expansion; 
       FIG. 11  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string after expansion and during a well treatment process; 
       FIG. 12  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string after completion of the well treatment process and retrieval of the work string; 
       FIG. 13  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string and having a release member positioned therein prior to the release operation; 
       FIG. 14  is a half sectional view of an expandable production packer according to the present invention that has been released from a casing string using a release member; 
       FIG. 15  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string and having a release member positioned therein prior to the release operation; 
       FIG. 16  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string and having a release member positioned therein prior to the release operation; 
       FIG. 17  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string and having a release member positioned therein prior to the release operation; 
       FIG. 18  is a half sectional view of an expandable production packer according to the present invention that is positioned within a casing string and having a radial cutting tool positioned; and 
       FIG. 19  is a half sectional view of an expandable production packer according to the present invention that has been released from a casing string. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention. 
   Referring initially to  FIG. 1 , an expandable production packer of the present invention is being installed from an offshore oil and gas platform that is schematically illustrated and generally designated  10 . A semi-submersible platform  12  is centered over a submerged oil and gas formation  14  located below sea floor  16 . A subsea conduit  18  extends from deck  20  of platform  12  to wellhead installation  22  including subsea blow-out preventers  24 . Platform  12  has a hoisting apparatus  26  and a derrick  28  for raising and lowering pipe strings such as production tubing string  30 . 
   A wellbore  32  extends through the various earth strata including formation  14 . A casing  34  is cemented within wellbore  32  by cement  36 . Production tubing string  30  is coupled on its lower end to various tools including sand control screen assemblies  38 ,  40 ,  42  positioned adjacent to formation  14  and perforations  44  below expandable production packer  46 . 
   As explained in greater detail below, to provide a seal between casing  34  and production tubing  30 , expandable production packer  46  may be expanded. Accordingly, production tubing  30  includes, above and below expandable production packer  46  of the present invention, a launcher  52  and a catcher  54  between which an expander member  56  longitudinally travels to plastically deform expandable production packer  46 . In the illustrated embodiment, this is achieved by pressurizing production tubing string  30  between a plug  58  and the lower end of expander member  56  by pumping fluid down through a work string such as a jointed tubing string or, as illustrated, a coiled tubing string  59  that is coupled to expander member  56 . 
   Referring now to  FIGS. 2-5 , therein are depicted more detailed views of one method for creating a fluid seal between production tubing  30  and well casing  34  with an expandable production packer  46 . Expandable production packer  46  includes a plurality of seal elements  60 A- 60 E that are positioned around an expandable section of tubing string  30 . Once the expansion process is performed, seal elements  60 A- 60 E are placed in intimate contact with the interior wall of casing  34  to provide a sealing and gripping arrangement between production tubing  30  and casing  34 . To achieve this expansion, production tubing  30  includes launcher  52  and catcher  54 . Initially disposed within launcher  52  is expander member  56 . 
   It should be noted, however, by those skilled in the art that instead of installing production tubing string  30  in casing string  34  with expander member  56  already positioned within launcher  52 , an expander member could alternatively be run in after production tubing string  30  has been installed within casing string  34 . In this case, it may be necessary that the expander member have a smaller diameter running configuration such that it may be run in production tubing string  30  and through expandable production packer  46  prior to expansion and a larger diameter expansion configuration suitable for expanding expandable production packer  46  as described below. 
   In the illustrated embodiment, expander member  56  has a tapered cone section  62  which includes a receiver portion that is coupled to the lower end of coiled tubing string  59 . Initially, expander member  56  is coupled within launcher  52  by a shear pin (not pictured) or other suitable device that holds expander member  56  within launcher  52  but allows the release of expander member  56  as required. Also initially, plug  58  may be attached to the lower end of expander member  56 , as best seen in FIG.  2 . Once coiled tubing string  59  is coupled to expander member  56 , a longitudinal force may be applied to expander member  56  to release expander member  56  from attachment with launcher  52 . Thereafter, coiled tubing string  59 , together with expander member  56  and plug  58  may be lowered downhole until plug  58  is located within landing nipple  64 , as best seen in FIG.  3 . Plug  58  is then released from expander member  56  and coiled tubing string  59 , together with expander member  56  is raised uphole until expander member  56  is within launcher  52 , as best seen in FIG.  4 . 
   The diameter of the section of production tubing string  30  within expandable production packer  46  may now be increased by moving expander member  56  longitudinally through expandable production packer  46  from launcher  52  to catcher  54 . As best seen in  FIG. 5 , a fluid is pumped down coiled tubing string  59  into the portion of production tubing string  30  between plug  58  and the lower end of expander member  56 , as indicated by arrows  66 . The fluid pressure urges expander member  56  upwardly such that tapered cone section  62  of expander member  56  contacts the interior wall of expandable production packer  46 . As the fluid pressure increases, tapered cone section  62  applies a radially outward force to the wall of expandable production packer  46 . When this force is sufficient to plastically deform expandable production packer  46 , expander member  56  begins to travel longitudinally within expandable production packer  46 . 
   As the upward movement of expander member  56  progresses, expandable production packer  46  substantially uniformly expands from its original diameter to a diameter similar to the diameter of expander member  56 . As this expansion occurs, seal elements  60 A- 60 E progressively expand into intimate contact with casing  34 . Once seal elements  60 A- 60 E are expanded, a fluid seal is created between production tubing  30  and casing  34 . In addition, seal elements  60 A- 60 E anchor production tubing  34  within casing  34 . Seal elements  60 A- 60 E may be constructed from a polymeric material such as rubber or other non-metallic materials or may be constructed from a metal such as lead or other suitable material that can expand radially when the production tubing about which it is attached is expanded and that can provide a suitable fluid seal and gripping force against the interior of casing  34 . In addition, it should be understood by those skilled in the art that even though  FIGS. 2-5  have depicted five seal elements  60 A- 60 E attached to a section of production tubing  30  to form production packer  46 , other numbers of seal elements both greater than and less than five could alternatively be used without departing from the principles of the present invention. In fact, a significant advantage of the production packers of the present invention is that numerous independent seal elements may be placed along one or more sections of the production tubing string which not only improves the reliability of the seal between the production tubing and the well casing but also improves the anchoring capability as the anchoring force is spread across a large area. 
   In addition, as seal elements  60 A- 60 E provide both sealing and anchoring capabilities, the slips typically associated with production packers are not required, which, among other things, significantly reduces the complexity and cost of expandable production packers  46  of the present invention versus conventional production packers. If additional anchoring capability is desired with expandable production packers  46 , however, the outer surface of the section of tubing string  30  of expandable production packer  46  may be serrated to increase the friction between expandable production packer  46  and the inner surface of casing  34 . 
   It should be noted by those skilled in the art that the force necessary to plastically deform expandable production packer  46  is dependant upon a variety of factors including the ramp angle of tapered cone section  62 , the amount of the desired expansion of expandable production packer  46 , the material of expandable production packer  46  and the like. Since only a short section of expandable production packer  46  is being expanded at any one time, however, the fluid pumped through coiled tubing string  59  typically provides sufficient upward force to expander member  56  to expand that section of expandable production packer  46 . This force may be controlled by adjusting the flow rate and pressure at which the fluid is delivered through coiled tubing string  59 . 
   The upward force of expander member  56  may be enhanced by pulling on expander member  56 , which may be accomplished by placing coiled tubing string  59  in tension. In fact, longitudinal movement of expander member  56  may be achieved completely mechanically by pulling expander member  56  through expandable production packer  46  by placing coiled tubing string  59  in sufficient tension. In this case, since no fluids are used to upwardly urge expander member  56 , no plug  58  below catcher  52  is necessary. In the illustrated embodiment, once the expansion process is complete, coiled tubing string  59 , expander member  56  and plug  58  may be retrieved to the surface. For example, expander member  56  may be returned to its runing configuration such that expander member  56  may travel back through expandable production packer  46  and be coupled to plug  58  prior to retrieval to the surface. Alternatively, coiled tubing string  59  and expander member  56  may be retrieved to the surface together and, thereafter, plug  58  may be retrieved by wireline or other suitable techniques. 
   It should be apparent to those skilled in the art that the use of direction terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrated embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward being toward the bottom of the corresponding figure. Accordingly, it should be noted that the expandable production packer of the present invention and the methods for setting the expandable production packer of the present invention are not limited to the vertical orientation as they are equally well suited for use in inclined, deviated and horizontal wellbores. 
   While  FIGS. 1-5  have depicted the expansion of expandable production packer  46  as progressing from a downhole location to an uphole location, the expansion could alternatively progress from an uphole location to a downhole location, as best seen in  FIGS. 6 and 7 . Specifically, production tubing string  70  is disposed within wellbore  32  having casing string  34  cemented therein with cement  36 . Disposed within production tubing string  70  is expandable production packer  72  including a plurality of seal elements  74 A- 74 E position around a section of production tubing string  70 . Above expandable production packer  72  is a launcher  76  into which an expander member  78  is placed. Expander member  78  includes a tapered cone section  80 , a piston  82  and an anchor section  84 . Anchor section  84  includes a receiver portion that is coupled to the lower end of coiled tubing string  86 . 
   In operation, a downward force is placed on expander member  78  by applying the weight of coiled tubing string  86  on expander member  78 . This downward force operates to stroke piston  82  to its compressed position, as best seen in FIG.  7 . Once piston  82  completes its downward stroke, fluid is pumped down coiled tubing string  86  which sets anchor section  84  creating a friction grip between anchor section  84  and the interior of expandable production packer  72  which prevents upward movement of anchor section  84 . More fluid is then pumped down coiled tubing string  86 , as indicated by arrow  88 , which urges tapered cone section  80  downwardly such that tapered cone section  80  places a radially outward force against the wall of expandable production packer  72  causing expandable production packer  72  to plastically deform creating a sealing and gripping connection between production tubing  70  and casing  34  with seal elements  74 A- 74 E. This process continues in a step wise fashion wherein each stroke of expander member  78  expands a section of expandable production packer  72 . After expandable production packer  72  has been expanded and expander member  78  has been returned to its running configuration, coiled tubing string  86  and expander member  78  may be retrieved to the surface. 
   Referring now to  FIGS. 8A-8B , therein are depicted more detailed views of expander member  78  in its expansion configuration and in its fully contracted and fully extended positions, respectively. Expander member  78  includes a tapered cone section  80 , a piston  82  and an anchor section  84 . Anchor section  84  includes a receiver portion  81  that may be coupled to the lower end of coiled tubing string  86  (not pictured). Anchor section  84  includes fluid ports  79 , coiled spring  83  and slips  85  that cooperate together such that when a fluid pressure is applied within expander member  78  and into fluid ports  79 , coiled spring  83  is compressed causing slips  85  to outwardly radially expand and grip the interior of expandable production packer  72  (not pictured). In addition, the fluid pressure acts on piston  82  on surface  86  and surface  87 , via fluid ports  88 , such that the force of the fluid pressure is multiplied. This force acting on piston  82  causes piston  82 , along with tapered cone section  80 , to be downwardly urged toward the position depicted in FIG.  8 B. Once expander member  78  has completed its stroke and expanded a length of expandable production packer  72  (not pictured), the fluid pressure in expander member  78  is allowed to bleed off such that expander member  78  may be collapsed back to the configuration depicted in FIG.  8 A and another stoke of expander member  78  may begin. 
   Referring now to  FIGS. 9-12 , therein is depicted another embodiment of a method for creating a fluid seal between production tubing and casing with an expandable production packer and treating a wellbore. Production tubing string  90  is disposed within wellbore  92  having a casing string  94  that is cemented within wellbore  92  with cement  96 . Tubing string  90  includes expandable production packer  96  having seal elements  98 A- 98 C. Tubing string  90  also includes treatment fluid ports  100  that are positioned downhole of expandable production packer  96 , return fluid ports  102  that are positioned uphole of expandable production packer  96 , a latch member  104  and a launcher  106 . A work string  108  having a latch member  110  is coupled to tubing string  90  at latch member  104 . Disposed within tubing string  90  and work string  108  is an expander member  112 . Expander member  112  includes a tapered cone section  114 , a cross-over section  116  and a piston section  118 . Disposed between expander member  112  and tubing string  90  is a plurality of seals  120  carried on expander member  112  to provide fluid sealing therebetween. 
   In operation, once tubing string  90  is properly positioned within casing  94  with expander member  112  therein, a fluid is pumped down work string  108  as indicated by arrows  122 . As best seen in  FIG. 10 , the fluid pressure urges tapered cone section  114  downwardly placing a radially outward force against the wall of expandable production packer  96  causing expandable production packer  96  to plastically deform creating a sealing and gripping connection between tubing string  90  and casing  94  with seal elements  98 A- 98 C. This process continues until piston section  118  reaches it full travel against shoulder  124 , as best seen in FIG.  11 . 
   At this point, seal elements  98 A- 98 C of expandable production packer  96  provide a seal between production tubing  90  and casing  94 . Also, cross-over section  116  traverses expandable production packer  96  with portions of cross-over assembly  154  on either side of packer  96 . As illustrated, when the treatment operation is a frac pack, the objective is to enhance the permeability of formation  14  (see  FIG. 1 ) by delivering a fluid slurry containing proppants at a high flow rate and in a large volume above the fracture gradient of the formation such that fractures may be formed within the formation and held open by the proppants. In addition, a frac pack also has the objective of preventing the production of fines by packing the annulus between sand control screens  38 ,  40 ,  42  (see  FIG. 1 ) and casing  34  with the proppants. To help achieve these results, a valve at the surface is initially in the closed position to prevent the flow of return fluids. 
   The fluid slurry containing proppants is then pumped down work string  108  and expander member  112  as indicated by arrows  130 . In the illustrated embodiment, the fluid slurry containing proppants exits expander member  112  and enters annulus  132  between casing  94  and production tubing  90 , via treatment fluid ports  100 . As the fluid slurry containing proppants is being delivered at a high flowrate and in a large volume above the fracture gradient of formation  14  and as no returns are initially taken, the fluid slurry fractures formation  14 . It should be noted that as the frac pack operation progresses some of the proppants in the fluid slurry screens out in annulus  132 , thereby packing annulus  132  around sand control screens  38 ,  40 ,  42 . This packing process may be enhanced by reducing the flow rate of the fluid slurry toward the end of the treatment process and opening the surface valve to allow some returns to flow to the surface. 
   Specifically, when the surface valve is opened, the liquid carrier of the fluid slurry containing proppants is allowed the travel through sand control screens  38 ,  40 ,  42  while the proppants are disallowed from traveling through sand control screens  38 ,  40 ,  42 . Accordingly, the proppants become tightly packed in annulus  132 . The return fluids, as indicated by arrows  134 , travel up tubing string  90  into expander member  112 . Return fluids  134  then travel through a micro-annulus  136  within expander member  112  and return fluid ports  102  before entering annulus  138  between work string  108  and casing  94  for return to the surface. It should be noted by those skilled in the art that even though a frac pack operation has been described, expander member  112  is equally well-suited for use in other well treatment operations including fracture operations, gravel pack operations, cementing operations, chemical treatment operations and the like. 
   After the process of creating the fluid seal between the casing and the production tubing as well as the process of well treatment is complete, work string  108  along with expander member  112  are retrieved to the surface, as best seen in FIG.  12 . This is achieved by releasing latch member  104  of tubing string  90  from latch member  110  of work string  108 . Thereafter, the rest of the production tubing string may be run downhole and attached to tubing string  90  at latch  104  or by other suitable means. 
   With all the above described embodiments of the expandable production packer of the present invention, it may be necessary to remove an expandable production packer of the present invention once it has been installed. Accordingly, the present invention provides several methods of releasing an expandable production packer of the present invention for retrieval. Referring now to  FIGS. 13-14 , therein are depicted one method of releasing an expandable production packer that is designated  150 . Expandable production packer  150  includes a plurality of seal elements  152 A- 152 E that are positioned around an expandable section of tubing string  154  that has previously been expanded using a technique described herein or other suitable technique. As illustrated, seal elements  152 A- 152 E are in intimate contact with the interior wall of casing  156  such that a sealing and gripping arrangement exists between production tubing  154  and casing 
   If it becomes necessary to retrieve expandable production packer  150 , the intimate contact of seal elements  152 A- 152 E with the interior of casing string  156  must be released. This is achieved using release member  158 . In the illustrated embodiment, release member  158  includes a pair of latching keys  160 ,  162  that respectively match and lock into latch profiles  164 ,  166  of tubing string  154 . Release member  158  also includes a piston section  168  and a receiver portion  170  that is coupled to the lower end of coiled tubing string  172  and that provides for fluid communication between coiled tubing string  172  and piston section  168 . Once release member  158  and coiled tubing string  172  are positioned as depicted in  FIG. 13 , an axially tensile force may be placed on expandable production packer  150  between latch profiles  164 , 
   Specifically, in the illustrated embodiment, a fluid is pumped downhole via coiled tubing string  172  and into piston section  168  placing expandable production packer  150  in tension between latch profiles  164 ,  166 . As the pressure increases within piston section  168 , the tensile force becomes sufficient to plastically deform expandable production packer  150  such that the diameter of expandable production packer  150  is reduced. Multiple factors work together to achieve this reduction. 
   For example, the tensile force placed on expandable production packer  150  causes elongation in the expandable section of tubing string  154  between latch profiles  164 ,  166 . This elongation results in a reduction in the diameter of this section of tubing  154  and accordingly a reduction in the diameter of seal elements  152 A- 152 E. In addition, the diameter of seal elements  152 A- 152 E is further reduced due to the elongations of seal elements  152 A- 152 E themselves. Further, the difference in the diameter of tubing  154  between latch profiles  164 ,  166  and the diameter of tubing  154  at latch profiles  164 ,  166  cause a radially inward force to act on tubing  154  between latch profiles  164 ,  166  while the tensile force is being applied. Accordingly, under sufficient tensile force, the diameter of tubing  154  between latch profiles  164 ,  166  is reduced such that the intimate contact between seal elements  152 A- 152 E and the interior of casing string  156  is released, as best seen in FIG.  14 . Thereafter, tubing string  154  along with expandable production packer  150  can be retrieved to the surface. 
   It should be noted by those skilled in the art that the force necessary to plastically deform expandable production packer  150  and allow release thereof is dependant upon a variety of factors including the difference in the diameter of tubing  154  between latch profiles  164 ,  166  and the diameter of tubing  154  at latch profiles  164 ,  166 , the amount of expansion originally achieved by expandable production packer  150 , the material of expandable production packer  150  and the like. It should be noted that the tensile force may be controlled by adjusting the fluid pressure delivered through coiled tubing string  172 . Additionally, it should be understood by those skilled in the art that even though  FIG. 14  depicts the diameter of tubing  154  between latch profiles  164 ,  166  being reduced such that no contact between seal elements  152 A- 152 E and the interior of casing string  156  remains, some contact between one or more of the seal elements  152 A- 152 E and the interior of casing string  156  is acceptable as long as expandable production packer  150  can be retrieved to the surface. 
   Referring now to  FIG. 15 , therein is depicted another method of releasing an expandable production packer that is designated  180 . Expandable production packer  180  includes a plurality of seal elements  182 A- 182 E that are positioned around an expandable section of tubing string  184  that has previously been expanded using a technique described herein or other suitable technique. As illustrated, seal elements  182 A- 182 E are in intimate contact with the interior wall of casing  186  such that a sealing and gripping arrangement exists between production tubing  184  and casing  186 . 
   If it becomes necessary to retrieve expandable production packer  180 , the intimate contact of seal elements  182 A- 182 E with the interior of casing string  186  must be released. This is achieved using release member  188  that includes a pair of latching keys  190 ,  192  that respectively match and lock into latch profiles  194 ,  196  of tubing string  184 . Release member  188  also includes a piston section  198 . Release member  188  may be run downhole on a conveyance  200  such as a jointed tubing, a coiled tubing, a wireline, a slickline, an electric line or the like. Coupled between conveyance  200  and release member  188  is an operating assembly  202 . 
   In one embodiment, conveyance  200  is a wireline and operating assembly  202  is a hydraulic pump. In this embodiment, the wireline may be used to stroke the hydraulic pump such that fluid is pumped into piston section  198 , thereby placing an axially tensile force on expandable production packer  180  between latch profiles  194 ,  196  which elongates this section of tubing  184 , as described herein, allowing for the release of expandable production packer  180 . 
   In another embodiment, conveyance  200  is an electric line and operating assembly  202  is an electrical hydraulic pump. In this embodiment, the electricity provides the energy to operate the hydraulic pump such that fluid is pumped into piston section  198 , thereby placing an axially tensile force on expandable production packer  180  between latch profiles  194 ,  196  which elongates this section of tubing  184 , as described herein, allowing for the release of expandable production packer  180 . 
   In yet another embodiment, conveyance  200  is an electric line and operating assembly  202  is a downhole power unit. In this embodiment, the electricity provides the energy to operate the downhole power unit to rotate a shaft that drives piston section  198 , thereby placing an axially tensile force on expandable production packer  180  between latch profiles  194 ,  196  which elongates this section of tubing  184 , as described herein, allowing for the release of expandable production packer  180 . 
   In a further embodiment, conveyance  200  is an electric line and operating assembly  202  includes both a downhole power unit and a hydraulic pump. In this embodiment, the downhole power unit may be used to stroke the hydraulic pump such that fluid is pumped into piston section  198 , thereby placing an axially tensile force on expandable production packer  180  between latch profiles  194 ,  196  which elongates this section of tubing  184 , as described herein, allowing for the release of expandable production packer  180 . 
   In all of these embodiments, once sufficient tensile force is generated and the diameter of tubing  184  between latch profiles  194 ,  196  is reduced, the intimate contact between seal elements  182 A- 182 E and the interior of casing string  186  is released, such that tubing string  184  along with expandable production packer  180  can be retrieved to the surface. 
   Referring now to  FIG. 16 , therein is depicted another method of releasing an expandable production packer that is designated  210 . Expandable production packer  210  includes a plurality of seal elements  212 A- 212 E that are positioned around an expandable section of tubing string  214  that has previously been expanded using a technique described herein or other suitable technique. As illustrated, seal elements  212 A- 212 E are in intimate contact with the interior wall of casing  216  such that a sealing and gripping arrangement exists between production tubing  214  and casing  216 . 
   If it becomes necessary to retrieve expandable production packer  210 , the intimate contact of seal elements  212 A- 212 E with the interior of casing string  216  must be released. This is achieved using release member  218 . In the illustrated embodiment, release member  218  includes a pair of latching keys  220 ,  222  that respectively match and lock into latch profiles  224 ,  226  of tubing string  214 . Release member  218  also includes seal elements  228 ,  230  that respectively create a fluid seal against seal bores  232 ,  234 . Release member  218  further includes a piston section  236  and a receiver portion  238  that is coupled to the lower end of coiled tubing string  240  and that provides for fluid communication between coiled tubing string  240  and piston section  236 . 
   As described herein, once release member  218  and coiled tubing string  240  are positioned as depicted in  FIG. 16 , an axial force may be placed on expandable production packer  210  between latch profiles  224 ,  226  by pumping a fluid into piston section  236  via coiled tubing string  240 . In this embodiment, not only does this tensile force cause elongation in the expandable section of tubing string  214 , elongation of seal elements  212 A- 212 E and a radially inward force based upon the difference in the diameter of tubing  214  between latch profiles  224 ,  226  and the diameter of tubing  214  at latch profiles  224 ,  226 , this tensile force also create a collapse force surrounding expandable production packer  210 . 
   Specifically, as expandable production packer  210  is elongated, the volume within expandable production packer  210  between seal elements  228 ,  230  also expands. This expansion causes a drop in the pressure of the fluids trapped in this volume creating a differential pressure across the wall of expandable production packer  210 . This differential pressure creates a radially inwardly acting collapse force on expandable production packer  210 , which aids in the diameter reduction of tubing  214  between latch profiles  224 ,  226  such that the intimate contact between seal elements  212 A- 212 E and the interior of casing string  216  is released. Thereafter, tubing string  214  along with expandable production packer  210  can be retrieved to the surface. 
   It should be understood by those skilled in the art that release member  218  as described herein could alternatively be used as an expander member to set an expandable production packer of the present invention. Specifically, by reconfiguring piston section  236 , fluid pressure delivered via coiled tubing string  240  could provide compression to the expandable section of tubing string  214  between latch profiles  224 ,  226 . As this section of tubing  214  begins to shorten, the volume within expandable production packer  210  between seal elements  228 ,  230  is reduced. This reduction causes an increase in the pressure of the fluids trapped in this volume creating a differential pressure across the wall of expandable production packer  210 . This differential pressure creates a radially outwardly acting expansion force on expandable production packer  210 , which aids in the diameter expansion of tubing  214  between latch profiles  224 ,  226  such that intimate contact between seal elements  212 A- 212 E and the interior of casing string  216  can be created. 
   Referring now to  FIG. 17 , therein is depicted another method of releasing an expandable production packer that is designated  250 . Expandable production packer  250  includes a plurality of seal elements  252 A- 252 E that are positioned around an expandable section of tubing string  254  that has previously been expanded using a technique described herein or other suitable technique. As illustrated, seal elements  252 A- 252 E are in intimate contact with the interior wall of casing  256  such that a sealing and gripping arrangement exists between production tubing  254  and casing  256 . 
   If it becomes necessary to retrieve expandable production packer  250 , the intimate contact of seal elements  252 A- 252 E with the interior of casing string  256  must be released. This is achieved using release member  258 . In the illustrated embodiment, release member  258  includes a pair of seal elements  260 ,  262  that respectively create a fluid seal against seal bores  264 ,  266 . Release member  258  further includes a mandrel section  268  having a plurality of ports  270  and a receiver portion  272  that is coupled to the lower end of coiled tubing string  274  and that provides for fluid communication between coiled tubing string  274  and mandrel section  268 . 
   Once release member  258  and coiled tubing string  274  are positioned as depicted in  FIG. 17 , a collapse force may be created surrounding expandable production packer  250  by depressurizing the volume within expandable production packer  250 . Specifically, once fluid communication is established between this volume and the interior of coiled tubing string  274  by, for example, operating a sleeve valve to open ports  270 , the pressure of the fluids within this volume may be reduced by, for example, having a relatively light fluid within coiled tubing string  274 , which creates a differential pressure across the wall of expandable production packer  250 . This differential pressure creates a radially inwardly acting collapse force on expandable production packer  250 , such that the intimate contact between seal elements  252 A- 252 E and the interior of casing string  256  is released. Thereafter, tubing string  254  along with expandable production packer  250  can be retrieved to the surface. 
   Referring now to  FIGS. 18-19 , therein are depicted another method of releasing an expandable production packer that is designated  280 . Expandable production packer  280  includes a plurality of seal elements  282 A- 282 E that are positioned around an expandable section of tubing string  284  that has previously been expanded using a technique described herein or other suitable technique. As illustrated, seal elements  282 A- 282 E are in intimate contact with the interior wall of casing  286  such that a sealing and gripping arrangement exists between production tubing  284  and casing  286 . 
   If it becomes necessary to retrieve expandable production packer  280 , the intimate contact of seal elements  282 A- 282 E with the interior of casing string  286  must be released. This is achieved by weakening the sections of tubing  284  behind seal elements  282 A- 282 E using a radial cutting tool  288 . In the illustrated embodiment, radial cutting tool  288  may be run downhole on an electric line  290  until a latching key  292  of radial cutting tool  288  locks into latch profile  294 . Radial cutting tool  288  may use any one of several cutting techniques that are well known in the art including, but not limited to, chemical cutting, thermal cutting, mechanical cutting, explosive cutting or the like. 
   For example, radial cutting tool  288  may be a chemical cutter such as that described in U.S. Pat. No. 5,575,331, which is hereby incorporated by reference. Once in place, radial cutting tool  288  is operated to cut a series of notches or grooves into the interior wall of expandable production packer  280  behind seal elements  282 A- 282 E. In the case of using the chemical cutter, a dispersed jet of cutting fluid is released through cutting ports  296 . In the illustrated embodiment, cutting ports  296  are circumferentially positioned at  90  degree intervals around radial cutting tool  288  such that the portion of tubing  284  behind seal elements  282 A- 282 E will have a series of axially oriented grooves or notches that are circumferentially positioned at 90 degree intervals relative to one another. It should be noted by those skilled in the art, however, that other cutting configurations may alternatively be used without departing from the principles of the present invention. 
   The chemical cutter is fired by an electrical signal carried via electric line  290 . The depth of cut made by the chemical cutter is predetermined and is controlled by the composition of chemicals loaded into the chemical cutter and the geometry of cutting ports  296 . Preferably, the chemical cutter is set to make a cut that partially penetrates the wall of expandable production packer  280  behind seal elements  282 A- 282 E. 
   Once the grooves or notches have been cut into expandable production packer  280  behind seal elements  282 A- 282 E by radially cutting tool  288 , radial cutting tool  288  may be retrieved to the surface. Thereafter, as best seen in  FIG. 19 , a plug  298  may be set below expandable production packer  280  and a sealing member  300  coupled to the lower end of a coiled tubing string  302  may be set above expandable production packer  280 . A collapse force may then be created surrounding expandable production packer  280  by depressurizing the volume within expandable production packer  280 . Specifically, once fluid communication is established between this volume and the interior of coiled tubing string  302  by, for example, operating a valve within seal member  300 , the pressure of the fluids within this volume may be reduced by, for example, having a relatively light fluid within coiled tubing string  302 , which creates a differential pressure across the wall of expandable production packer  280 . This differential pressure creates a radially inwardly acting collapse force on expandable production packer  280 . As the sections of tubing  284  behind seal elements  282 A- 282 E have been weakened as described herein, the collapse force acts preferentially on these sections, such that the intimate contact between seal elements  282 A- 282 E and the interior of casing string  286  is released. Thereafter, tubing string  284  along with expandable production packer  280  can be retrieved to the surface. 
   Even though  FIGS. 18-19  have been described with reference to weakening the sections of tubing  284  behind seal elements  282 A- 282 E using a radial cutting tool  288  to create notches or grooves in tubing  284 , it should be understood by those skilled in the art the such a radial cutting tool could alternatively be used to completely cut through the sections of tubing  284  behind seal elements  282 A- 282 E. In this case, the collapse force that is created surrounding expandable production packer  280  by depressurizing the volume within expandable production packer  280  may be reduced or that step may be eliminated while still allowing release of seal elements  282 A- 282 E from the interior of casing string  286 . 
   While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.