Patent Publication Number: US-2023133516-A1

Title: Predetermined Load Release Device for a Jar

Description:
This application is a continuation of U.S. application Ser. No. 17/229,575 filed Apr. 13, 2021, which is a continuation of U.S. application Ser. No. 16/255,315 filed Jan. 23, 2019, issued as U.S. Pat. No. 10,975,649 on Apr. 13, 2021, which is a continuation of U.S. application Ser. No. 14/618,074 filed Feb. 10, 2015, issued as U.S. Pat. No. 10,208,554 on Feb. 19, 2019, each of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention relates to a release mechanism for a jarring device used in conjunction with the drilling and/or completion of oil or gas wells. Jarring devices are typically used in conjunction with drilling or completion tubular strings positioned within a well to impart an upward or downward force on a tool carried by the string should the tool or string become lodged within the well. 
     2. Description of Related Art 
     U.S. Pat. No. 5,139,086 discloses a double acting jar having a first end for connection to a work string and a second end  2  for connection to the tool which may become struck in the wellbore. The jar includes accumulator springs  4  and  5  which act to accumulate energy in two directions. Also disclosed are latch bars, bias spring  13  and bushings  12 . The amount of force necessary to release jarring mandrel  2  is determined by the adjustment of bias spring  13  which acts on latch bars  11  via bushings  12 . Latch bars  11  include ridges  17  which are positioned in a groove  16  on the jarring mandrel. The more compressive force applied to latch bars  11 , more force is required to displace ridges  17  out of groove  16  thereby enabling the jarring mandrel to be released. 
     U.S. Pat. No. 5,330,018 discloses a similar latch mechanism including latch bars  160 , ridges  170  and  182  and grooves  100  and  118  located in mandrel  100 . 
     The release mechanisms of the prior art have the disadvantage of excessive wear and increased friction which reduces the effectiveness and reliability of the jar. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the prior art as discussed above by providing a predetermined release mechanism for a jar that reduces drag and wear to a minimum. Springs such as Belleville springs are compressed within a split housing. A collet is positioned between a jarring mandrel and a trigger sleeve. The trigger sleeve surrounds the collet and the mandrel. A force sufficient to overcome the force exerted by the springs is required before the mandrel is released thereby allowing the jar to operate. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG.  1    is a partial cross-sectional view of a release device for a jar according to a first embodiment of the invention in a neutral position. 
         FIG.  1   a    is an enlargement of the dotted area labeled  FIG.  1   a    in  FIG.  1   . 
         FIG.  2    is a partial cross-sectional view showing the mandrel in a released position. 
         FIG.  2   a    is an enlarged view of the area designed  FIG.  2   a    in  FIG.  2   . 
         FIG.  3    is a partial cross-sectional view of a second embodiment according to the invention in a neutral position. 
         FIG.  3   a    is an enlargement of the area designated  3   a  in  FIG.  3     
         FIG.  4    is a cross-sectional view of the release device taken along lines  4 - 4  of  FIG.  1   . 
         FIG.  5    is a cross-sectional view of the embodiment of  FIG.  3    showing the mandrel in a released position. 
         FIG.  5   a    is an enlarged view of the area designated  5   a  in  FIG.  5   . 
         FIG.  6    is a cross-sectional view of a jarring tool according to an embodiment of the invention. 
         FIG.  7    is a cross-sectional view taken along line  7 - 7  of  FIG.  6   . 
         FIG.  8    is a partial cross-sectional view of a release device according to a third embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG.  1   , an embodiment of the release device  10  includes a first annular outer housing member  11  and second and third housing members  62  and  61  threadably attached to housing member  11 . Unless otherwise stated, it should be understood that the elements shown in the figures are annular members that surround the central tubular mandrel  48  of the jarring device as shown in  FIG.  4   . 
     A first Belleville spring stack  42  is confined within a first split ring housing  41  by flanges  45  and  44 . Housing  41  is formed by two semi-circular members so that they can be positioned over and surrounding spring  42  after spring  42  has been compressed. Bushing  43  has a first portion  81  that engages the end of Belleville spring stack  42  and a second portion  82  that engages collet  21  at  22  as shown in  FIG.  1     a.    
     An annular collet  21  having a first end  22  and a second end  23  is positioned on mandrel  48  and includes a plurality of grooves  30  and ridges  29  as in known in the art. Collet  21  may include a plurality of longitudinally extending slots to facilitate radial expansion of the collet. The outer surface of mandrel  48  includes a plurality of grooves  33  and ridges  32  that in the neutral position of  FIG.  1    engage with the ridges  29  and grooves  30  of the collet. In this position mandrel  48  is restrained from axial movement by virtue of bushings  43  and  18  and springs  42  and  13 . 
     A second Belleville spring stack  13  is confined within a second slit ring housing  12  by virtue of flanges  54  and  55  and bushings  18  and  17 . Second Belleville spring stack  13  may be precompressed to a value greater or less than or equal to that of first Belleville spring stack  42 . Spring stacks  42  and  13  may include a plurality of spring guides  84  and  85  as disclosed in U.S. Pat. No. 7,854,425 issued Dec. 21, 2010. 
     Three concentric sleeve members  24 ,  25  and  26  surround collet  21  and mandrel  48  and are positioned between collet  21  and housing  11  as shown in  FIG.  1     a.    
     Central sleeve  25  is a trigger sleeve that includes a plurality of annular grooves  27  and a plurality of annular ridges  28 . Ridges  28  of trigger sleeve  25  rest on ridges  29  of collet  21  in the neutral position as shown in  FIG.  1   a   . Sleeves  24 ,  25  and  26  are loosely confined in the space between housing  11  and annular collet  21 ; that is they are not secured structurally to any member. 
     In the neutral position shown in  FIG.  1   a   , springs  42  and  13  are under compression and will resist movement of the collet  21  in both directions that is in an upwardly or downwardly direction. Assuming that motion of the mandrel  48  to the left as shown in  FIG.  2    constitutes an upward movement, as an upward force is placed on the mandrel  48  via a tubular string, collet  21  cannot move to the left until the force exerted by spring  42  stack and bushing  43  on the collet at  22  is overcome. Thus, collet  21  will not move to the left until a predetermined force is exceeded. 
     In the neutral or unloaded position there is a gap between the sleeves  24 ,  25  and  26  and the split sleeves  41  and  12 . As an axial load is applied in either direction, the angular engagement between the ridges  29  in the ID of the collet and the grooves  33  on the OD of the mandrel  48  cause the collet  21  to expand radially and engage the ID of the trigger sleeve  25 . The frictional force between the OD of the ridges  29  of the collet  21  and the ID of the ridges  28  of the trigger sleeve  25  will cause the trigger sleeve  25  to be biased in the direction of motion of the collet  21 . If a force is applied to the mandrel in the upward direction sufficient to exceed the preload of the spring stack  42  the sequence of operation would be 1) the mandrel would engage the collet and cause it to engage the bushing  43  and the spring stack  42 ; 2) the collet would expand such that the ridges  29  would engage the ridges  28  of the trigger sleeve  25  and cause the trigger sleeve  25  to load the sleeve  24  until the gap at  83  closes and a gap occurs at  86 ; 3) as additional load is applied the trigger sleeve  24  and sleeve  25  are prevented from upward motion by split housing  41  and housing member  62 ; 4) as additional load is applied the ridges  29  of collet  21  slide inside ridges  28  of trigger sleeve  25  until the ridges  29  of collet  21  come into registration with grooves  27  of trigger sleeve  25 ; and 5) at the point of registration the trigger sleeve will move in the opposite direction due to the gap at  86  and allow the collet to release without wear or damage. The load at which the mandrel is released is known as the trigger load or release load and will be somewhat greater than the preload. 
     After the collet  21  releases the mandrel  48  the spring stack  42  will be compressed to the release load which will be slightly greater load than the preload due to the additional compression of the spring stack as shown at  75  in  FIG.  2   . The release load is maintained because the spring stack  42  is compressed between annular bushings  46  and  43 . Bushing  43  abuts housing member  62  and is thus restrained from upward movement. Ring  43  transfers the release load to the collet  21 . Collet  21  is engaged with trigger sleeve  25  which causes the trigger sleeve  25  to load sleeve  26  which loads the split housing  12  and finally the load is transferred to housing member  61 . There will be some drag on the mandrel  48  as it moves through the collet  21  because the release load is acting on the collet  21  and trigger sleeve  25 . The angular faces of the protrusions  28  in the trigger sleeve  25  and the mating ridges  29  of the collet will cause the collet to collapse and create a drag force as the mandrel  48  moves through the collet  21 . 
     If a force were applied to mandrel  48  in a direction opposite to that shown in  FIG.  2   , then mandrel  48  would move to the right as shown in  FIG.  2    and a similar release of the mandrel from collet  21  would occur. In this case, spring stack  13  would be compressed by collet  21  through annular bushing  18 . 
       FIGS.  3  and  3     a  illustrate a second embodiment according to the invention. This embodiment is similar to that shown and described in  FIGS.  1  and  1     a  in that it includes housing  11 ,  61  and  62 , spring stacks  42  and  13 , split ring housings  41  and  12 , bushings  46 ,  43 ,  19  and  17 , mandrel  48  and collet  21 . It also includes three concentric sleeves  71 ,  72  and  73 . Sleeve  72  is also a trigger sleeve. 
     A plurality of annular round wire wave springs known as Wavo® springs  51 ,  52 ,  53  and  54  are positioned between split housing  41 , sleeves  71 ,  72  and  73  and split housing  12  as shown in  FIG.  3     a.    
     The operation of the collet and trigger sleeve are similar that shown in  FIGS.  1  and  1     a . As the mandrel begins to compress the collet between the mandrel grooves and the bushing  43  the collet expands and causes the trigger sleeve to move with the collet due to the friction force between the OD of the ridges  29  of the collet and the ridges  28  of the trigger sleeve. The friction force between the collet and trigger sleeve will cause springs  51  and  52  to become compressed until the trigger sleeve bears on sleeve  71  which in turn bears on split sleeve  41  and housing member  62 . At this point the collet will move relative to the trigger sleeve until the mandrel moves to the release point where the OD ridges  29  of the collet are in registration with the ID grooves  27  of the trigger sleeve. At this point the spring stack  42  is compressed as shown in  75  in  FIG.  2   a   . The trigger sleeve will instantly release the collet as previously explained. However, the addition of the Wavo® springs allow the spring stack  42  to compress the springs at  53  and  54  as shown in  FIG.  5   a    until the load of the spring stack  42  is again trapped between the flanges  45  and  44  of split housing  41 . The Wavo® springs pushing on the trigger sleeve and collet will cause the collet to collapse and drag on the mandrel but the magnitude of the drag force will be reduced by a factor of at least 10. 
       FIG.  6    illustrates a complete jarring tool utilizing the release mechanism of  FIGS.  1  and  2   . The release mechanism could also be used in conjunction with the embodiment of the release mechanism shown in  FIGS.  3 - 5   . 
     Referring to  FIG.  6    the jarring tool includes a housing having upper portions  102  and  103 , middle portion  11 ,  112  and a lower portion  111 . Connector  110  and threads  115  are provided for connecting the lower end of the jarring tool to a tubular string. The jarring tool also includes a mandrel having an upper portion  49 , a middle portion  48  and a lower portion  114 . 
     The upper portion  49  is connected to a connector  101  for attaching the upper portion of the jarring tool to a tubular string. 
     The various portions of the housing are connected together for example by threads  122 ,  123 ,  125 ,  126 ,  128  and  129 . The individual portions of the mandrel are connected together for example by threads  124  and  127 . Seals are located between the housing and mandrel portions at  131 ,  132 ,  133 ,  134 ,  135 ,  136 ,  137  and  138 . 
     A floating piston  116  surrounds the lower portion  114  of the mandrel. Fluid fittings  114  and  115  are provided for introduction of suitable lubricants into the interior of the jarring tool as is well known in the art. With regard to surfaces that would impact based on an upward force, an anvil surface  105  is located at the end of housing portion  102 , and a hammer surface  106  is located on the mandrel portion  49 . With regard to surfaces that would impact due to a downward force, anvil surface  105  is located at the end of housing member  62  and hammer surface  106  is located on the mandrel portion  49  as shown in  FIG.  6   . 
     As shown in  FIG.  7   , upper portion  49  of the mandrel and the inner surface of housing member  103  may have a hexagonal cross-section as shown at  104  and  105 . 
       FIG.  8    illustrates a third embodiment of the invention with respect to the arrangement of holding the pre-loaded springs in the housing. The elements that are the same as those in the embodiment of  FIGS.  1  and  1     a  have been labeled the same. Referring to  FIG.  8    an intermediate housing member  101  has an annular interior ridge  102  that together with shoulder  110  on housing member  62  and bushing  43  retains first spring stack  42 . 
     Intermediate housing member  101  has an annual groove  103  which receives a segmented ring  107 . Second spring stack  13  is confined between shoulder bushing  18  and shoulder  111  on housing member  61 . 
     Spring stacks  42  and  13  are pre-loaded by threads  105  and  106  between intermediate housing member  101  and housing members  62  and  61 . 
     MODE OF OPERATION 
     In the neutral position shown in  FIG.  1   , collet  21  locks mandrel  48  in place via the grooves and ridges of the collet and the mandrel. Movement of the collet in an upward or downward direction is resisted by springs  42  and  13  which are precompressed and exert a force on the collet by virtue of bushings  43  and  18 . If a force greater than the compression force of spring  42  is exerted in an upward direction (or to the left as shown in  FIG.  1   ) on mandrel  48 , collet  21  and mandrel will begin to move to the left while further compressing spring  42 . As the ridges  29  of collet  21  come into registry with grooves  27  of the trigger sleeve, collet  21  will expand outwardly thereby releasing the collet from the mandrel. The mandrel will then be free to exert a jarring force as it moves the position of  FIG.  2   . In a similar manner, if a downward force is applied to the mandrel that exceeds the compression force of the spring, collet  21  will compress spring  13  and the collet will then separate from the mandrel and expand into the trigger sleeve. The embodiment of  FIGS.  3  and  3     a  operates in the same manner. However, when an upward force is put on the mandrel and the mandrel is released as shown in  FIGS.  5  and  5     a , Wavo® springs  53  and  54  will be compressed so that no gap similar to that shown at  75  exits. Thus the force is transmitted through collet  21  and trigger  72  thereby compressing springs  53  and  54 . Consequently the force on the collet and trigger sleeve is from Wavo® springs  53  and  54 , not through spring  43 , which would be considerably higher. 
     As is understood in the art, the grooves and ridges of the trigger sleeve, collet and mandrel are angled so that their respective surfaces can slide with respect to each other. 
     Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.