Patent Publication Number: US-11643901-B2

Title: Uphole end for a compression-set straddle packer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 17/101,377 filed Nov. 23, 2020 which was a continuation of U.S. patent application Ser. No. 16/289,805 filed Mar. 1, 2019, now U.S. Pat. No. 10,900,320 which issued on Jan. 26, 2021. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to precision fracking systems and, in particular, to a novel uphole end for a compression-set straddle packer that can be used for cased wellbore or open hole well stimulation or remediation. 
     BACKGROUND OF THE INVENTION 
     Wellbore pressure isolation tools, commonly referred to as “straddle packers”, are known and used to pressure isolate a downhole area of interest in a cased or open hydrocarbon wellbore for the purpose of what is known as focused or precision well stimulation or remediation. Straddle packers designed for this purpose are well known, but their use has been associated with operational issues that frequently render them unreliable. Most straddle packers are also complex tools that are expensive to build and maintain. 
     There therefore exists a need for a novel uphole end for a compression-set straddle packer that permits virtually any compression set packer to be connected to the uphole end to provide a straddle packer that will operate reliably in a downhole environment. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an uphole end for a compression-set straddle packer. 
     The invention therefore provides an uphole end for a compression-set straddle packer, comprising: a multicomponent mandrel having a work string connection end that supports a packer element, the multicomponent mandrel extending from the work string connection end to a connection joint of the uphole end, the multicomponent mandrel including a bias element push component and a bias element support component; a multicomponent sliding sleeve that surrounds the multicomponent mandrel below the work string connection end and reciprocates on the multicomponent mandrel within a limited range, the multicomponent sliding sleeve including the connection joint, an transition sleeve upper end and a transition sleeve lower end that provide a bias element chamber to house the bias element push component and the bias element support component; and a bias element supported on the bias element support component of the multicomponent mandrel between the bias element push component and a lower end of the bias element chamber, the bias element constantly resisting any movement of the multicomponent sliding sleeve with respect to the multicomponent mandrel. 
     The invention further provides an uphole end for a compression-set straddle packer, comprising: a multicomponent mandrel having a work string connection end that supports a packer element, the multicomponent mandrel extending from the work string connection end to a connection joint of the uphole end, a work string connection component on the work string end; an upper mandrel tube threadedly connected to the work string connection component; a mandrel flow sub connected to a downhole end of the upper mandrel tube; at least one mandrel flow sub nozzle in the mandrel flow sub; a lower mandrel tube connected to a downhole end of the mandrel flow sub; a bias element push component connected to a downhole end of the lower mandrel tube; a bias element support component connected to a downhole end of the bias element push component and a mandrel termination component connected to a downhole end of the bias element support component; a multicomponent sliding sleeve that surrounds the multicomponent mandrel below the work string connection end and reciprocates on the multicomponent mandrel within a limited range, the multicomponent sliding sleeve including an upper sliding sleeve connected to a compression bell that slides over a downhole end of a packer element sleeve of the work string connection component, the upper sliding sleeve sliding over the upper mandrel tube; a slotted sliding sleeve connected to a downhole end of the upper sliding sleeve, the slotted sliding sleeve sliding over the mandrel flow sub and having slotted sliding sleeve finger components that define slots that expose the at least one mandrel flow sub nozzle; a lower sliding sleeve connected to a downhole end of the slotted sliding sleeve; an transition sleeve upper end connected to a downhole end of the lower sliding sleeve; a transition sleeve lower end connected to a downhole end of the transition sleeve upper end, the upper and lower sliding sleeves providing a bias element chamber that houses the bias element push component and the bias element support component of the multicomponent mandrel; and the connection joint which is connected to the transition sleeve lower end; and a bias element supported on the bias element support component of the multicomponent mandrel between the bias element push component and a lower end of the bias element chamber, the bias element constantly resisting any movement of the multicomponent sliding sleeve with respect to the multicomponent mandrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, in which: 
         FIG.  1    is a perspective view of an embodiment of an uphole end for a compression-set straddle packer in accordance with the invention; 
         FIG.  2   a    is a cross-sectional view of the uphole end for a compression-set straddle packer shown in  FIG.  1   ; 
         FIG.  2   b    is an enlarged cross-sectional view of the uphole end for a compression-set straddle packer shown in  FIG.  2   ; 
         FIG.  3    is a cross-sectional view of the uphole end for a compression-set straddle packer showing the uphole end as it would appear if the straddle packer were in a packer-set condition; 
         FIG.  4    is a perspective view of one embodiment of a bias element of the uphole end for a compression-set straddle packer in accordance with the invention; 
         FIG.  5    is a side elevational view of the bias element shown in  FIG.  4   ; 
         FIG.  6    is a perspective view of another embodiment of the uphole end for a compression-set straddle packer in accordance with the invention; 
         FIG.  7    is a cross-sectional view the embodiment of the uphole end shown in  FIG.  6   ; and 
         FIG.  8    is a cross-sectional view a further embodiment of the uphole end for a compression-set straddle packer in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention provides an uphole end for a compression-set straddle packer. The uphole end may be connected to substantially any compression-set packer to provide a straddle packer that may be used in precision well stimulation or remediation treatments in either open hole or cased wellbores (hereinafter referred to collectively as “wellbores”). A length of a zone that is pressure isolated by the straddle packer may be adjusted, if desired, by inserting tubular extensions between a connection joint of the uphole end and the compression-set packer. The uphole end has a multicomponent mandrel that extends from an upper end to a lower end thereof. A multicomponent sliding sleeve surrounds the multicomponent mandrel and reciprocates within a limited range over the multicomponent mandrel. The multicomponent mandrel includes a mandrel flow sub component. The mandrel flow sub has at least one abrasion-resistant fluid nozzle used to inject well stimulation or well remediation fluid (hereinafter referred to collectively as “high pressure fluid”) into a section of a wellbore that is pressure isolated by a packer element of the uphole end and a packer element of the connected compression-set packer when the respective packer elements are in a packer set condition. In this document, “flow sub nozzle” means any orifice, permanent or interchangeable, through which high pressure fluid may be pumped, including but not limited to a bore and a slot. In the packer set condition the respective packer elements are in high pressure sealing contact with a wellbore. The respective packer elements are compressed to the packer set condition by work string weight applied at surface to a work string connected to the uphole end. A bias element is captured between a bias element push component of the multicomponent mandrel and a lower end of a bias element chamber provided by the multicomponent sliding sleeve. The bias element constantly resists relative movement of the multicomponent mandrel with respect to the multicomponent sliding sleeve. 
     When the compression-set packer is being set using work string manipulation in a manner required by the compression-set packer being used, string weight overcomes the resistance of the bias element, which slides the multicomponent mandrel within the multicomponent sliding sleeve to set the packer on the uphole end and pressure isolate a section of the well bore. High-pressure fluid may then be pumped through the work string into the pressure isolated section of the well bore. When the high-pressure fluid treatment is completed and string weight is released from the work string, the bias element assists unsetting of the respective packers. In one embodiment the bias element is an elastomeric tube received on the multicomponent mandrel. In one embodiment, the multicomponent mandrel includes ports under the bias element and the bias element chamber wall includes ports above the bias element. When the packers are set, the bias element seals the respective ports in the multicomponent mandrel and the bias element chamber wall. When string weight is released from the uphole end, the bias element relaxes and opens the respective ports, which permits fluid in the multicomponent mandrel to flow around opposite ends of the bias element and into the well bore, which can facilitate recovery from a “screen-out” should one occur. 
     
       
         
           
               
               
             
               
                   
               
               
                 Part No. 
                 Part Description 
               
               
                   
               
             
            
               
                 10 
                 Uphole end for a compression-set straddle packer 
               
               
                 11 
                 Multicomponent mandrel 
               
               
                 12 
                 Work string connection component 
               
               
                 13 
                 Multicomponent mandrel central passage 
               
               
                 14 
                 Work string connection 
               
               
                 15 
                 Packer element compression shoulder 
               
               
                 16 
                 Packer element sleeve 
               
               
                 17 
                 Multicomponent sliding sleeve 
               
               
                 18 
                 Packer element 
               
               
                 19 
                 Packer element compression ring 
               
               
                 20 
                 Compression bell 
               
               
                 21 
                 Compression bell pressure equalization ports 
               
               
                 22 
                 Upper crossover tube 
               
               
                 23 
                 Upper mandrel tube 
               
               
                 24 
                 Upper sliding sleeve 
               
               
                 25 
                 Upper sliding sleeve threaded connection 
               
               
                 26 
                 Upper sliding sleeve coupling 
               
               
                 27 
                 Slotted sliding sleeve female coupling end 
               
               
                 28 
                 Slotted sliding sleeve 
               
               
                 29 
                 Sliding sleeve finger components 
               
               
                 30 
                 Mandrel flow sub 
               
               
                 31 
                 Mandrel flow sub grooves 
               
               
                 32 
                 Mandrel flow sub nozzles 
               
               
                 34 
                 Lower sliding sleeve coupling 
               
               
                 36 
                 Lower sliding sleeve 
               
               
                 38 
                 Slotted sliding sleeve captured end coupling ring 
               
               
                 40 
                 Cap screws 
               
               
                 42 
                 Lower mandrel tube 
               
               
                 44 
                 Bias element push component 
               
               
                 46 
                 Bias element support component 
               
               
                 48 
                 Mandrel termination component 
               
               
                 50 
                 Transition sleeve upper end 
               
               
                 52 
                 Transition sleeve lower end 
               
               
                 54 
                 Connection joint 
               
               
                 56 
                 Bias element chamber 
               
               
                 58 
                 Bias element 
               
               
                 60 
                 Upper bias element push ring 
               
               
                 62 
                 Lower bias element push ring 
               
               
                 64 
                 Mandrel ports 
               
               
                 66 
                 Transition sleeve ports 
               
               
                 68 
                 Bias element uphole end 
               
               
                 70 
                 Bias element downhole end 
               
               
                 72 
                 Bias element central passage 
               
               
                 74 
                 Bias element outer vent groove 
               
               
                 76 
                 Bias element inner vent groove 
               
               
                 78 
                 Transition sleeve slots 
               
               
                 80 
                 Compression spring 
               
               
                   
               
            
           
         
       
     
       FIG.  1    is a perspective view of one embodiment of the uphole end  10  for a compression-set straddle packer (hereinafter for the sake of simplicity, simply “uphole end  10 ”) in accordance with one embodiment of the invention. The uphole end  10  has a multicomponent mandrel  11 , the majority of which can only be seen in a cross-sectional view (see  FIGS.  2   a  and  2   b   ). The multicomponent mandrel  11  extends completely through the uphole end  10  and is surrounded by a multicomponent sliding sleeve  17 , which reciprocates within a limited range over the multicomponent mandrel  1 . The multicomponent mandrel  11  includes a work string connection component  12  with a work string connection  14  (see  FIG.  2   a   ). A configuration of the work string connection  14  is a matter of design choice and dependent on whether the uphole end  10  is to be operated using a coil tubing string (not shown) or jointed tubing string (not shown), as is well understood in the art. 
     The work string connection component  12  has a packer element compression shoulder  15  and a packer element sleeve  16  (see  FIG.  2   a   ) that supports an elastomeric packer element  18 , the function of which is well understood in the art. On a downhole side of the packer element  18  is a packer element compression ring  19  that slides on the packer element sleeve  16 . A compression bell  20 , having compression bell equalization ports  21 , is a component of the multicomponent sliding sleeve  17  and is connected to an upper sliding sleeve  24 . The upper sliding sleeve  24  is connected by an upper sliding sleeve thread connection  25  to an upper sliding sleeve coupling  26 , which is in turn connected to a female coupling end  27  (see  FIG.  2   b   ) of a slotted sliding sleeve  28 . In one embodiment, the slotted sliding sleeve  28  has three slotted sliding sleeve finger components  29  that are respectively received in mandrel flow sub grooves  31  in the mandrel flow sub  30 . The slotted sliding sleeve finger components  29  define three slots that respectively expose at least one mandrel flow sub nozzle of a mandrel flow sub  30 . In this embodiment, the mandrel flow sub  30  has a plurality of mandrel flow sub nozzles,  32 . It should be understood the number of mandrel flow sub nozzles is a matter of design choice. A downhole end of the sliding sleeve finger components  29  are threadedly connected to a slotted sliding sleeve captured end coupling ring  38  that surrounds a lower sliding sleeve coupling  34  (see  FIG.  2   a   ) that is threadedly connected to a lower sliding sleeve  36 . A downhole end of the lower sliding sleeve  36  is connected to a transition sleeve upper end  50  that is in turn connected to a transition sleeve lower end  52 . A connection joint  54 , which is the final component of the multicomponent sliding sleeve  17 , is connected to a lower end of the transition sleeve lower end  52 . The connection joint  54  is used to connect a compression-set packer (not shown) to the uphole end  10  to provide a straddle packer. The compression-set packer may be connected directly to the connection joint  54 , or one or more extension pipes (not shown) can be connected to the connection joint  54 , in which case the compression-set packer is connected to a lower end of the extension pipe(s) to increase a length of a well bore that is pressure isolated by the straddle packer. 
       FIG.  2   a    is a cross-sectional view of the uphole end  10  shown in  FIG.  1   . As explained above, the slotted sliding sleeve  28  is connected to the lower sliding sleeve  36  by the lower sliding sleeve coupling  34 , which is threadedly connected to both the slotted sliding sleeve  28  and the lower sliding sleeve  36 . The slotted sliding sleeve captured end coupling ring  38  that covers the lower sliding sleeve coupling is likewise threadedly connected to the slotted sliding sleeve  28 . Rotation of the slotted sliding sleeve captured end coupling ring  38  is inhibited by cap screws  40 . As further explained above, the elastomeric packer element  18  is supported on the packer element sleeve  16  of the work string connection component  12  of the multicomponent mandrel  11 . The multicomponent mandrel  11  has a central passage  13  that provides an uninterrupted fluid path through the multicomponent mandrel  11 . The multicomponent mandrel  11  includes the following interconnected components: the work string connection component  12 , which is threadedly connected to an upper crossover tube  22  (better seen in  FIG.  2   b   ); threadedly connected to a lower end of the upper crossover tube  22  is an upper mandrel tube  23 ; the mandrel flow sub  30  connected to a downhole end of upper mandrel tube  23 ; the wear-resistant, replaceable mandrel flow sub nozzle(s)  32 ; a lower mandrel tube  42  connected to a downhole end of the mandrel flow sub  30 ; a bias element push component  44  connected to a downhole end of the lower mandrel tube  42 ; a bias element support component  46  having mandrel ports  64  connected to a downhole end of the bias element push component  44 ; and, a mandrel termination component  48  connected to a lower end of the bias element support component  46 . 
       FIG.  2   b    is an enlarged cross-sectional view of the uphole end  10  in  FIG.  2   . All of the external and internal components of the uphole end  10  have been described above except for one important operative component, namely a bias element  58  housed in a bias element chamber  56  within the transition sleeve upper end  50  and the transition sleeve lower end  52  components of the multicomponent sliding sleeve  17 . In one embodiment the bias element  58  is an elastomeric tube carried on the bias element support component  46 . In one embodiment the tubular bias element  58  is cast from a hydrogenated nitrile butadiene rubber (HNBR) having a durometer of at least  90 . An upper bias element push ring  60  abuts an upper end of the bias element  58 . A lower bias element push ring  62  abuts a lower end of the bias element  58 . Both the upper bias element push ring  60  and the lower bias element push ring  62  float on the bias element support component  46 . The bias element  58  constantly resists any movement of the upper bias element push ring  60  toward the lower bias element push ring  62 , and vice versa, thus resisting any relative movement of the multicomponent sliding sleeve  17  over the multicomponent mandrel  11 . As will be explained below with reference to  FIG.  3   , the bias element  58  serves several important functions in the operation of the uphole end  10 . 
       FIG.  3    is a cross-sectional view of the uphole end  10  showing the uphole end  10  as it would appear if it was connected to a compression-set packer to provide a straddle packer and the straddle packer were in a packer-set condition. In the set condition the bias element  58  is compressed by work string weight applied from the surface in a manner well understood in the art. When work string weight is applied to the work string connection component  12 , The multicomponent mandrel  11  is forced downhole and slides downward within the multicomponent sliding sleeve  17 . This urges the bias element push component  44  and the upper bias element push ring  60  to compress the bias element  58  as the bias element support component  46  is forced downhole through the lower bias element push ring  62 . The compressed bias element  58  urges the multicomponent sliding sleeve  17  downhole as the uphole end  10  is forced downhole to set the compression-set packer (not shown) in a manner well known in the art. Meanwhile, movement of the multicomponent mandrel  11  urges the packer element compression shoulder  15  against the packer element  18  to set the packer element  18 . In addition, as the bias element  58  compresses under the work string weight load it increases in diameter to fill the bias element chamber  56  (see  FIG.  2   b   ) sealing mandrel ports  64  in the bias element support component  46  and transition sleeve ports  66  in the transition sleeve upper end  50  to prevent any escape of high-pressure fluid pumped into the uphole end  10  through the mandrel ports  64 . However, if a screen-out (well understood in the art) occurs, relieving work string weight at the surface lets the bias element  58  relax as shown in  FIG.  2   b   , opening the mandrel ports  64  and providing a fluid path around opposed ends of the relaxed bias element  58  and out through the transition sleeve ports  66  to permit high-pressure fluid trapped in the uphole end  10  to drain into an annulus of the well bore. The bias element  58  also assists the return of the uphole end  10  to the run-in position after string weight is removed from the work string, and prevents premature setting of the packer element  18  in the event a minor obstruction is tagged in the well bore while the straddle packer is being run into the well bore. 
       FIG.  4    is a perspective view of one embodiment of a bias element  58  of the uphole end  10  in accordance with the invention. In this embodiment, the bias element  58  has a bias element uphole end  68  and a bias element downhole end  70 . However, the bias element  58  is symmetrical and may be inserted with either end uphole. A wide external bias element outer vent groove  74  and a corresponding bias element inner vent groove  76  (see  FIG.  5   ) ensure that the mandrel ports  64  and the transition sleeve ports  66  remain open when the bias element  58  is in a relaxed condition. A bias element central passage  72  is sized to accept the bias element support component  46  of the multicomponent mandrel  11 .  FIG.  5    is a side elevational view of the bias element  58  shown in  FIG.  4   . 
       FIG.  6    is a perspective view of another embodiment of an uphole end  10   a  for a compression-set straddle packer in accordance with the invention. This embodiment of the uphole end  10   a  has all of the components and features of the uphole end described above with reference to  FIGS.  1 - 5    with an exception that the ports in the transition sleeve upper end  50  are elongated transition sleeve slots  78  to encourage fluid egress in an event that a screen out occurs when fluid heavily laden with proppant is being pumped through the uphole end  10   a .  FIG.  7    is a cross-sectional view the embodiment of the uphole end  10   a  shown in  FIG.  6   . 
       FIG.  8    is a cross-sectional view a further embodiment of an uphole end  10   b  for a compression-set straddle packer in accordance with the invention. All of the components and features of the uphole end  10   b  have been described above with reference to  FIGS.  1 - 5    except that the bias element in the uphole end  10  is a bias element compression spring  80 . The uphole end  10   b  also has only the upper bias element push ring  60 , and the bias element support component  46  has no ports. Furthermore, there are no ports in the transition sleeve upper end  50 . In one embodiment of the uphole end  10   b , the bias element compression spring  80  is preloaded with about 2,000 pounds of compression when the uphole end  10   b  is assembled, and maintains that tension in an unset condition of the uphole end  10   b . The uphole end  10   b  is operated in the same manner as described above with reference to the uphole end  10 . 
     The explicit embodiments of the invention described above have been presented by way of example only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.