Patent Publication Number: US-10309564-B1

Title: Extendable spool

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to oil or gas wellbore equipment, and, more particularly, to an extendable spool connector. 
     BACKGROUND 
     Accounting for length variances on non-permanent, pressurized, fluid-flow lines is normally accomplished by redirecting the flow through one or more turns until the desired length is achieved. Examples of the traditional length make-up methods are seen with hoses (via their flexible nature) and swiveling elbows (e.g., Chiksans). However, flow redirection through elbows or hoses accelerates erosion, especially when there are particulates in the fluid and/or when the fluid is flowing at a high rate, as seen during hydraulic fracturing operations. Erosion is accelerated not only on the parts redirecting the flow, but also on parts downstream. 
     Another drawback of using flow redirection for length make-up is that the method is not easily scalable to larger diameters—the required wall thicknesses quickly make installation difficult at best, to impractical at worst; therefore, traditional flow redirection lines used to make up for length variances are, relatively speaking, smaller diameters. One drawback of only being able to redirect flow with small diameter lines is that multiple redirected-flow lines must be used to account for length differences between large diameter lines. Therefore, what is needed is an apparatus, system, or method that addresses one or more of the foregoing issues, among one or more other issues. 
     SUMMARY OF THE INVENTION 
     The extendable spool accounts for length variances by extending the flow line rather than redirecting the flow. Because the flow direction does not make any turns, erosion is minimized on both the extendable spool and downstream parts. The extendable spool is readily scalable from small diameters to large diameters. Because of this, it requires fewer lines and therefore less setup time to account for length differences between large diameter lines. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure. In the drawings, like reference numbers may indicate identical or functionally similar elements. 
         FIG. 1  is a side view of an embodiment of an extendable spool in its fully contracted position. 
         FIG. 2  is a side view of the embodiment of  FIG. 1  in its fully extended position. 
         FIG. 3  is an isometric cutaway view of the embodiment of  FIG. 1  in its fully contracted position. 
         FIG. 4  is an isometric cutaway view of the embodiment of  FIG. 1  in its fully extended position. 
         FIG. 5  is an isometric view of the embodiment of  FIG. 1  in its fully extended position. 
         FIG. 6  is an alternative embodiment of an extendable spool. 
     
    
    
     DETAILED DESCRIPTION 
     In an exemplary embodiment,  FIGS. 1 and 2  schematically illustrate an extendable spool  100 . The extendable spool  100  is a flow spool with a variable length.  FIG. 1  illustrates the extendable spool  100  in fully contracted or compressed configuration, and  FIG. 2  illustrates it in its fully extended configuration. The length is able to be varied continuously, rather than discretely, between the fully contracted and fully extended configurations.  FIGS. 3 and 4  show isometric cutaway views of an embodiment of an extendable spool in fully contracted and fully extended positions. 
     The structure for two tubular sections of the extendable spool  100  through which fluid flows are described first. These sections are the threaded tube  101  and the inner tube  102 . Each tubular section is designed to withstand pressurized fluids that may be used in hydraulic fracturing or other high-pressure downhole operations. The threaded tube  101  may have an inner diameter, referenced in  FIG. 1  as ‘A,’ that is equivalent to the inner diameter of other tubular equipment to which the extendable spool may be connected. The threaded tube  101  may comprise an inner beveled shoulder  120  at which point the inner diameter of the threaded tube  101  increases from ‘A’ to a larger diameter ‘B.’ This increased diameter ‘B’ of the threaded tube  101  allows it to accommodate the outer diameter of inner tube  102 . The inner surface of the threaded tube  101  and the outer surface of inner tube  102  are both smooth, such that the inner tube  102  is able to freely move axially within the increased inner diameter of the threaded tube  101 . If inner tube  102  has an inner diameter of ‘A,’ then increased inner diameter ‘B’ of the threaded tube  101  will be substantially similar to diameter ‘A’ plus twice the wall thickness of inner tube  102 . 
     The inner beveled shoulder  120  of the threaded tube  101  may act as a physical stop to the inward axial movement of inner tube  102  when inner tube  102  is axially moved relative to threaded tube  101 . The inner tube  102  comprises an outer shoulder  130  which similarly may act a physical stop to the inward axial movement of inner tube  102  relative to threaded tube  101 . The inner end portion of inner tube  102  may include a beveled end cap called a wash cone  107  which may be threadably engaged with inner tube  102 . In an embodiment, the wash cone  107  may be integral to inner tube  102 . The wash cone  107  has an outer diameter that is equal to the outer diameter of the inner tube  102 , and the inner diameter of the wash cone  107  varies radially along the bevel from the inner diameter of the inner tube  102  to the increased inner diameter of the threaded tube  101 . 
     In the embodiment above, both the inner beveled shoulder  120  of the threaded tube  101  and the beveled surface of wash cone  107  are configured to gradually change their inner diameter from ‘A’ to ‘B.’ Accordingly, there are no abrupt interior edges along the flow path through the threaded tube  101  and the inner tube  102 , even when the threaded tube  101  and inner tube  102  are configured to different axial lengths of the extendable spool  100 . 
     The ends of the threaded tube  101  and the inner tube  102  may each threadably engage with a spool flange  103 , which enables both ends of the extendable spool  100  to be connected to other tubular equipment. In an embodiment, the spool flanges may be integral to the threaded tube  101  and the inner tube  102 . 
     Sealing between the threaded tube  101  and the inner tube  102  is accomplished via seals  113 , such as o-rings, that sit in grooves on the outer surface of the inner tube  102 . Similarly, the wash cone  107  may accommodate one or more seals  113  in grooves on its outer surface. The seals  113  mate with a corrosion resistant sealing surface on the inner surface of the threaded tube  101 . Bronze pieces  109 ,  110 , and  111  may be used to facilitate sliding between the different steel parts. 
     The structure for setting and fixing the length of the extendable spool  100  is now described. As noted above, the threaded tube  101  and the inner tube  102  are movable relative to each other. They may be fixed relative to each other using other components, including tensile tube  104 , inner wing  105 , and outer wing  106 . Referring still to  FIGS. 1 and 2 , the threaded tube  101  includes a threaded outer surface with which the inner wing  105  is threadably engaged. The axial location of the inner wing  105  along the threaded outer surface of the threaded tube  101  serves to define the length of extendable spool  100  and the position of the tensile tube  104 , as will be described further below. 
     Still referring to  FIGS. 1 and 2 , the tensile tube  104  may be threadably engaged with inner tube  102  at or around the outer shoulder  130  of inner tube  102 . Aside from the inner threaded connection that tensile tube  104  uses to connect to the outer shoulder  130  of inner tube  102 , the inner surface of tensile tube  104  is smooth and not threaded. This allows the inner tube  102  and the tensile tube  104  together to freely move axially with respect to threaded tube  101  even though the outer surface of threaded tube  101  is threaded. The inner tube  102  and the tensile tube  104  are axially positioned such that the tensile tube  104  abuts the inner wing  105 . As shown in  FIGS. 1  and  2 , the inner wing  105  and the tensile tube  104  abut at beveled ends, which allows the inner wing  105  to have a longer thread on its outer surface. In another embodiment, the inner wing  105  and the tensile tube  104  abut at straight ends. 
     Tensile tube  104  is fixed in place by outer wing  106 , which threadably engages with the threaded outer surface of inner wing  105 , and which locks the position of tensile tube  104  by engaging with a mating shoulder  140  of tensile tube  104 . 
     To change the length of the extendable spool  100 , the inner wing  105  and outer wing  106  are unscrewed from each other, which allows outer wing  106  and tensile tube  104  to axially move relative to each other, and also allows tensile tube  104  and inner tube  102  to move relative to threaded tube  101 . To extend the length of the spool  100 , hydraulic cylinders (shown as element  150  in  FIG. 5 ) can be used to stroke the extendable spool  100  to a desired length by longitudinally moving the tensile tube  104  and the inner tube  102  relative to threaded tube  101 . Once the desired length is reached, the inner wing  105  is screwed to the desired position, or until inner wing  105  abuts tensile tube  104 . In order to minimize the number of turns required to move inner wing  105  into the desired position, the outer surface of threaded tube  101  may be configured with multiple-start threads. Once inner wing  105  is in the desired position, outer wing  106  is screwed back on to inner wing  105  to lock the position of tensile tube  104 . 
     If the operator desires to bring the ends of the spool closer together, the outer wing  106  is unscrewed from the inner wing  105 , and the inner wing  105  must be backed away from the tensile tube  104  until inner wing  105  reaches the desired position. Then, hydraulic cylinders can retract the two ends together until the tensile tube  104  makes contact with the inner wing  105  again. The inner and outer wings  105  and  106  are then screwed back together to lock the spool  100  at the desired length. 
     It should be noted that, although tensile tube  104  and inner tube  102  are shown as threadably engaged, they may also be connected using pins, bolts, or any other known method of connecting tubular members. The only requirement of the tensile tube is that it remain connected to inner tube  102  in order to transfer longitudinal force from one end of the spool to the other and to facilitate adjustment of the length of the extendable spool as described above. As a result, tensile tube  104  and inner tube  102  could be formed as a single piece without departing from the scope of the present disclosure. 
     The threads on the outer surface of threaded tube  101  may be left-hand, or reverse, threads, such that relative counter-clockwise rotation will cause engagement of threaded tube  101  and the inner threads of inner wing  105 . The threads that connect the wings (the outer threads of the inner wing  105  and the inner threads of outer wing  106 ) may be right-hand threads, such that relative clockwise rotation will cause engagement of the outer threads of inner wing  105  and inner threads of outer wing  106 . The combination of right-hand threads at the inner-to-outer wing connection and left-hand threads at the inner-wing-to-threaded tube connection ensures that tightening the wings tightens both ends of the spool together. To accomplish this optional objective, the particular orientation of the two threaded portions of the inner wing is not important; in other words, it is irrelevant which set of threads is right-handed and which set of threads is left-handed. What matters is that the orientation of the threads that connect the inner wing to the outer wing is the opposite of the orientation of the threads that connect the inner wing to the threaded tube. The inner wing  105  and outer wing  106  may have radially outwardly extending protrusions, or lugs, which facilitate screwing and unscrewing. 
       FIG. 6  illustrates an alternate embodiment of an extendable spool  200 . In this embodiment, the threaded tube  201  maintains a constant inner diameter ‘A.’ Inner tube  202  has an outer diameter that is substantially equal to ‘A’ and an inner diameter ‘C’ that is smaller. Other components and aspects of the extendable spool  200  are similar to those described above. 
     It is understood that variations may be made in the foregoing without departing from the scope of the present disclosure. In several exemplary embodiments, the elements and teachings of the various illustrative exemplary embodiments may be combined in whole or in part in some or all of the illustrative exemplary embodiments. In addition, one or more of the elements and teachings of the various illustrative exemplary embodiments may be omitted, at least in part, and/or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments. 
     Any spatial references, such as, for example, “upper,” “lower,” “above,” “below,” “between,” “bottom,” “vertical,” “horizontal,” “angular,” “upwards,” “downwards,” “side-to-side,” “left-to-right,” “right-to-left,” “top-to-bottom,” “bottom-to-top,” “top,” “bottom,” “bottom-up,” “top-down,” etc., are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above. 
     In several exemplary embodiments, while different steps, processes, and procedures are described as appearing as distinct acts, one or more of the steps, one or more of the processes, and/or one or more of the procedures may also be performed in different orders, simultaneously and/or sequentially. In several exemplary embodiments, the steps, processes, and/or procedures may be merged into one or more steps, processes and/or procedures. 
     In several exemplary embodiments, one or more of the operational steps in each embodiment may be omitted. Moreover, in some instances, some features of the present disclosure may be employed without a corresponding use of the other features. Moreover, one or more of the above-described embodiments and/or variations may be combined in whole or in part with any one or more of the other above-described embodiments and/or variations. 
     Although several exemplary embodiments have been described in detail above, the embodiments described are exemplary only and are not limiting, and those skilled in the art will readily appreciate that many other modifications, changes and/or substitutions are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, changes, and/or substitutions are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, any means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Moreover, it is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the word “means” together with an associated function.