Abstract:
A packer having a thermal memory spacing system that includes a portion of the system that that selectively changes an outer diameter due. The packer may include upper and lower sealing elements, and at least one thermal memory shape material sub positioned between the sealing elements. The thermal memory shape material sub may have a first outer diameter at a first temperature and a second larger outer diameter at a second temperature. The first temperature may be greater than the second temperature. The outer diameter of the sub may be selectively increased to temporarily decrease the annular area in which debris and/or materials may collect and potentially cause the packer to become stuck within the wellbore. Prior to moving the packer to a different location, the outer diameter of the sub may be decreased to increase the annular area.

Description:
FIELD OF THE DISCLOSURE 
     The embodiments described herein relate to a packer having a thermal memory spacing system that includes a portion of the system that that changes the outer diameter due to temperature and method of using the thermal memory spacing system. 
     BACKGROUND 
     Description of the Related Art 
     Packing devices, such as straddle packers, may be conveyed into a wellbore to be used to selectively isolate a portion of the wellbore. The isolation of a portion of the wellbore may be done for various reasons such as treating and/or fracturing the formation adjacent to the casing of the portion being isolated by the packer. While the packer is set against the casing it is quite common for debris and/or material to accumulate in the annulus between the packer and the casing as well as above the packer. In some instances, the accumulation of debris and/or material can cause it to be difficult to unset the packer when the treatment process has finished. Further, the debris and/or material can cause the packer to become stuck within the wellbore, not permitting the packer to be moved to another location within the wellbore. 
     SUMMARY 
     The present disclosure is directed to a packer that includes a thermal memory sub and method of using the thermal memory sub that overcomes some of the problems and disadvantages discussed above. 
     One embodiment is a packer comprising an upper sealing element, a lower sealing element, and a first sub positioned between the upper and lower sealing elements, the first sub being comprised of a memory shape material. At a first temperature the first sub has a first outer diameter and at a second temperature the first sub has a second outer diameter, the second outer diameter being larger than the first outer diameter. 
     The first temperature may be greater than the second temperature. The packer may include a fluid displacement sub positioned between the upper and lower sealing elements, the fluid displacement sub may have at least one port that permits fluid communication between an interior of the fluid displacement sub and an exterior of the fluid displacement sub. The packer may comprise a second sub positioned between the upper and lower sealing element, the second sub may be comprised of a memory shape material. The second sub may have a first outer diameter at the first temperature and may have a second outer diameter at the second temperature. The second outer diameter of the second sub may be larger than the first outer diameter. The fluid displacement sub may be positioned between the first sub and the second sub. The packer may comprise a third sub positioned above the upper sealing element. The third sub may be comprised of a memory shape material and may have a first outer diameter at the first temperature and may have a second outer diameter at the second temperature. The second diameter of the third sub may be larger than the first diameter. The first temperature may be greater than the second temperature. 
     The memory shape material may be a memory shape alloy. The memory shape alloy may be nickel titanium alloy, nickel titanium zirconium alloy, titanium nickel copper alloy, copper aluminum manganese alloy, iron nickel cobalt aluminum tantalum boron alloy, copper aluminum niobium alloy, nickel manganese gallium alloy, zirconium copper alloy, polycrystalline iron nickel cobalt aluminum alloy, polycrystalline iron manganese aluminum nickel alloy, polycrystalline nickel titanium zirconium niobium alloy, or combination thereof. The memory shape material may be a memory shape polymer. The first temperature may be at least approximately five degrees Fahrenheit greater than the second temperature. The second diameter of the first sub may be at least 5% larger than the first diameter of the first sub. 
     One embodiment is a method of treating a portion of a wellbore. The method comprises positioning a packer connected to a tubing string adjacent a first portion of a wellbore, the packer comprising an upper sealing element, a lower sealing element, a fluid displacement sub, and at least one sub comprised of a memory shape material having a first outer diameter at a first temperature and having a second outer diameter at a second temperature. The fluid displacement sub and the at least one sub each positioned between the upper and lower sealing elements. The method comprises actuating the upper and lower sealing elements to selectively isolate the first portion of the wellbore and treating the first portion of the wellbore. The method comprises changing a temperature of the isolated first portion of the wellbore to the second temperature, wherein the at least one sub as the second outer diameter which is different than the first outer diameter. 
     The second outer diameter of the at least one sub may be larger than the first outer diameter of the at least one sub. Treating the first portion of the wellbore may comprise pumping fluid down the tubing string and out the fluid displacement sub. Treating the first portion of the wellbore may comprise fracturing a formation by pumping fluid down the tubing string and out the fluid displacement sub. The formation may have been previously fractured and the formation may be re-fractured by the treatment. 
     The method may include changing the temperature of the isolated first portion of the wellbore to the first temperature after treating the first portion of the wellbore, wherein the at least one sub moves to the first outer diameter. The method may include unsetting the upper and lower sealing elements and moving the packer to a second portion of the wellbore. The at least one sub may have the first outer diameter as it is positioned adjacent to the first portion of the wellbore. The at least one sub may comprise a first sub positioned above the fluid displacement sub and a second sub positioned below the fluid displacement sub, wherein the first and second subs are both positioned between the upper and lower sealing elements. The method may include changing a temperature of the isolated first portion of the wellbore to the second temperature, which may actuate the first and second subs to their second outer diameters being larger than their first outer diameters. The method may include changing the temperature of the isolated first portion of the wellbore to the first temperature after treating the first portion of the wellbore, wherein the first temperature actuates the first and second subs to their first outer diameters being smaller than their second outer diameters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an embodiment of a packer having thermal memory subs isolating and treating a portion of a wellbore. 
         FIG. 2  shows an embodiment of a packer having thermal memory subs positioned within a wellbore. 
         FIG. 3  shows a cross-section of a portion of one embodiment of a packer with a thermal memory sub in an expanded state within a wellbore. 
         FIG. 4  shows a cross-section of a portion of a one embodiment of a packer with a thermal memory sub in a contracted state within a wellbore. 
         FIG. 5  shows a cross-section of a portion of one embodiment of a thermal memory sub in an expanded state. 
         FIG. 6  shows a cross-section of a portion of one embodiment of a thermal memory sub in a contracted state. 
         FIG. 7  shows a cross-section of a portion of one embodiment of a thermal memory sub in an expanded state. 
         FIG. 8  shows a cross-section of a portion of one embodiment of a thermal memory sub in a contracted state. 
         FIG. 9  shows a flow chart of an embodiment of a method of treating a portion of a wellbore. 
     
    
    
     While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  shows an embodiment of a packer  100  having thermal memory subs  140 A,  140 B, and  140 C positioned within a wellbore. The packer  100  may be connected to a tubing string  10  and run into a wellbore, which may include a casing  1 . The packer  100  may be positioned adjacent to perforations  2  in the casing  1  that permits fluid communication with the adjacent formation  5  and the wellbore. The formation  5  may be fractured  6  adjacent the perforations  2  in an attempt to increase the production of hydrocarbons from the formation  5 . 
     The packer  100  may include an upper sealing element  110 , upper slips  111 , upper blocks  112 , and an upper j-slot track  113 . The upper sealing element  110  may be set against the casing  1  to create a seal, as shown. The packer  100  may include a lower sealing element  120 , lower slips  121 , lower blocks  122 , and a lower j-slot track  123 . The lower sealing element  120  may be set against the casing  1  to create a seal, as shown. The packer  100 , including the various components, is for illustrative purposes only as various downhole packers may be used in connection with the thermal memory subs  140 A,  140 B, and  140 C disclosed herein. The upper and lower sealing elements  110  and  120  may be used to isolate a portion of the wellbore. The packer  100  may include a fluid displacement sub  130  with a port  131  or plurality of ports  131  that permit fluid communication from the tubing string  10  to the exterior of the fluid displacement sub  130 . The fluid displacement sub  130  may be connected between two thermal memory subs  140 B and  140 C. 
     The thermal memory subs  140 A,  140 B, and  140 C are configured so that the exterior of the subs  140 A,  140 B, and  140 C is comprised of a memory shape material that changes shape depending on the temperature. The thermal memory subs  140 A,  140 B, and  140 C may be configured so that the subs  140 A,  140 B, and  140 C have a first smaller outer diameter at a first temperature and have a second larger outer diameter at a second temperature. The second diameter may be approximately 10%, or more, larger or than the first diameter. However, the actual change in diameters may be configured based on the intended application. For example, a 5%, or even less, change in diameter may be sufficient in certain circumstances. The subs  140 A,  140 B, and  140 C may be comprised of various materials as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The memory shape material may be comprised of a memory shape alloy. For example, the subs  140 A,  140 B, and  140 C may be comprised of, but not limited to, nickel titanium alloy, nickel titanium zirconium alloy, titanium nickel copper alloy, copper aluminum manganese alloy, iron nickel cobalt aluminum tantalum boron alloy, copper aluminum niobium alloy, nickel manganese gallium alloy, zirconium copper alloy, polycrystalline iron nickel cobalt aluminum alloy, polycrystalline iron manganese aluminum nickel alloy, and polycrystalline nickel titanium zirconium niobium alloy. Alternatively, the sub  140  may be comprised of a memory shape polymer that permits the actuation between different shapes as would be appreciated by one or ordinary skill in the art having the benefit of this disclosure. 
     At a first temperature, the outer diameter of the thermal memory subs  140 A,  140 B, and  140 C may be smaller than the outer diameter of the thermal memory subs  140 A,  140 B, and  140 C at a second temperature. The first temperature may be hotter than the second temperature. In one embodiment, there may be at least a 5 degree Fahrenheit difference between the first and second temperatures. However, the difference between the first and second temperatures may be larger than 5 degrees Fahrenheit. For example, the difference between the first and second temperatures may be 10, 20, 25, 50, or more degrees Fahrenheit. As the temperature of the thermal memory subs  140 A,  140 B, and  140 C decreases the outer diameter of the thermal memory subs  140 A,  140 B, and  140 C may increase.  FIG. 1  shows the packer  100  positioned within the wellbore during treatment of the first portion of the wellbore, which may represent the second temperature. Thus, the outer diameter of the subs  140 A,  140 B, and  140 C is increased presenting less annular area between the subs  140 A,  140 B, and  140 C and the casing  1 . A smaller annular area between the subs  140 A,  140 B, and  140 C and the casing  1  may provide less area for the buildup of debris within the wellbore. As discussed herein, the later decrease in the outer diameter of the subs  140 A,  140 B, and  140 C may reduce the chance that the packer  100  becomes stuck within the wellbore as it is unset and attempted to be moved to another location. The treatment pumped through the port  131  of the fluid diversion sub  130  may comprise the injection of fluid into the formation or the fracturing, or re-fracturing, of a formation  5  adjacent the portion of the wellbore isolated by the sealing elements  110  and  120  of the packer  100 . 
     Once the treatment of the wellbore is completed, the temperature of the thermal memory subs  140 A,  140 B, and  140 C may raise to normal well temperatures, which may represent the first temperature. Thus, the outer diameter of the thermal memory subs  140 A,  140 B, and  140 C decreases enlarging the annular area between the subs  140 A,  140 B, and  140 C and the casing  1  as shown in  FIG. 2 . This enlarged area, in comparison to the annular area during the treatment process, may reduce the chance that the packer  100  will become stuck within the wellbore due to debris between the packer  100  and the casing  1 . The packer  100  may include a thermal memory sub  140 A above the upper sealing element  110  as well as multiple thermal memory subs  140 B and  140 C between the upper and lower sealing elements  110  and  120 . The packer  100  could also include a thermal memory sub below the lower sealing element  120 , if desired. The number and configuration of the thermal memory subs  140 A,  140 B, and  140 C is for illustrative purposes only and may be varied as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The thermal memory sub  140  provides a smaller annular area for the buildup of debris between the packer  100  and casing  1  during the treatment of the wellbore. The thermal memory sub  140  then provides a larger annular area when the packer  100  is to be unset and moved within the wellbore decreasing the likelihood that debris will cause the packer  100  will become stuck within the casing  1 . 
       FIG. 3  and  FIG. 4  shows a cross-section view of a packer  100  positioned within casing  1  of a wellbore. In  FIG. 3 , the packer  100  is at a first or lower temperature and the packer is at a second or higher temperature in  FIG. 4 . In  FIG. 4 , the outer diameter of the thermal memory sub  140  has contracted due to the movement of memory shape material so that the annular area  15  between the casing  1  and the sub  140  is larger in comparison to the annular area  15  of  FIG. 3 . 
       FIG. 5  and  FIG. 6  show a cross-section view of an embodiment of a thermal memory sub  140  having a core  141  and a memory shape material  142  positioned around the core  141 . The core  141  may have an inner diameter  143 .  FIG. 5  shows the thermal memory sub  140  at a first or lower temperature at which the thermal memory sub  140  has an outer diameter  144 A.  FIG. 6  shows the thermal memory sub  140  at a second or higher temperature at which the outer diameter  144 B has reduced in comparison to the outer diameter of  FIG. 5 . The inner diameter  143  of the core  141  does not change significantly in either the first or second temperatures.  FIG. 6  shows one embodiment on the potential change in shape of the memory shape material  142  to reduce the overall outer diameter of the thermal memory sub  140 . 
       FIG. 7  and  FIG. 8  show a cross-section view of an embodiment of a thermal memory sub  140  having a core  141  and a memory shape material  142  positioned around the core  141 .  FIG. 7  shows the thermal memory sub  140  at a first or lower temperature so that the memory shape material  142  extends away from the core  141  to increase the outer diameter or outer perimeter of the sub  140 .  FIG. 8  shows the thermal memory sub  140  at a second or higher temperature at which the memory shape material  142  contracts towards the core  141  reducing the outer diameter in comparison to the outer diameter of  FIG. 7 . 
       FIG. 9  shows a flow chart of one embodiment of a method  200  of treating a portion of a wellbore. The first step  210  is positioning a packer adjacent a first portion of the wellbore. The sealing elements of the packer are actuated to isolate the first portion of the wellbore in step  220 . The first portion of the wellbore is treated in step  230  and the temperature of the first portion of the wellbore is changed during the treatment process in step  240 . For example, the temperature may be lowered during the treatment process. However, the temperature could instead be raised during the treatment process. Optionally the treatment of the wellbore may comprise fracturing the wellbore in step  250  or re-fracturing the portion of the wellbore in step  260  if the wellbore has already been previously fractured. The changing of the temperature in step  240 , which is done contemporaneously with the treatment of the wellbore in step  230 , causes the increasing of an outer diameter of at least a portion, such as a sub comprised of a memory shape material, of the packer. Upon finishing the treatment process  230  of the wellbore, the temperature of the first portion of the wellbore is changed again in step  270 . For example, the temperature may be increased causing a reduction in an outer diameter of at least the portion of the packer, such as the sub comprises of the memory shape material. Alternatively, a reduction in the temperature may cause the reduction in an outer diameter of at least a portion of the packer. Treating the wellbore with the sub having a larger diameter reduces the annular area between the sub and the wellbore decreasing the amount of debris and other material that may collect in this area. After treating the wellbore has finished and the temperature increases, the outer diameter of the sub will reduce enlarging the annular area, which will decrease the chance that the packer will become stuck due to the debris within the annular area adjacent the sub. 
     Although this disclosure has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is defined only by reference to the appended claims and equivalents thereof.