Patent Publication Number: US-2016238002-A1

Title: Plunger lift assembly

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to oil field tools, and more particularly to an improved plunger lift assembly. 
     2. Description of Related Art 
     The oil and gas industry has been drilling and completing wells to produce hydrocarbons for decades. Plungers are downhole tools used by operators to remove liquids and contaminants from productive natural gas wells. A plunger acts as an artificial lift. In operation the plunger passes down through the well until it reaches a contact point in which the plunger seals shut. Pressure beneath the plunger builds and raises the plunger in the well, thereby removing all the liquids above the plunger. 
     A number of disadvantages exist with plungers. Bypass valve style plungers may have an external clutch retainer. The clutch retainer usually coupled directly to the cage. The cage and clutch retainer are located at the lower end of the plunger and experience great impact forces at the bottom of the well. The valve cage is typically thin-walled and susceptible breakage from the impact forces. Additionally, the clutch retainer being located externally, experiences direct impact forces at the bottom of the well and can be another failure point. When failed, pieces of the clutch and damaged retainer break from the plunger in the well, requiring each piece to be fished out, thereby increasing costs to the operator. Another disadvantage of bypass valve style plungers is the clutch. Clutches may typically be two-piece assemblies and use a spring wire or elastomeric bands to apply pressure. 
     An improved plunger assembly design is needed. Although great strides have been made, considerable shortcomings remain. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the application are set forth in the appended claims. However, the application itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an exploded perspective view of a plunger assembly according to the preferred embodiment of the present application 
         FIG. 2  is an enlarged side section view of a portion of the plunger assembly of  FIG. 1 ; 
         FIGS. 3 and 4  are enlarged side section views illustrating a stem used in the plunger lift assembly of  FIG. 1  in two different positions; 
         FIGS. 5-8  are associated views of an internal clutch assembly used in the plunger lift assembly of  FIG. 1 ; 
         FIGS. 9-10  are associated views of a clutch retainer used in the plunger lift assembly of  FIG. 1 ; 
         FIGS. 11-12  are associated views of a cage used in the plunger lift assembly of  FIG. 1 ; and 
         FIG. 13  is a bottom view of the cage of  FIG. 12  showing exemplary flow cut designs. 
     
    
    
     While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrative embodiments of the preferred embodiment are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in other desired orientations. Thus, the use of terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in other desired directions. 
     The system and method in accordance with the present application overcomes one or more of the above-discussed problems commonly associated with existing plunger assembly designs. Specifically, the system of the present application is configured to incorporate an internal clutch retainer, 3-piece clutch, and improved cage. The cage is configured to assist in the passage of liquids, hydrocarbons, and solids; and prevent premature wear and breakage typically associated from impact forces. These and other unique features of the system are discussed below and illustrated in the accompanying drawings. 
     The assembly will be understood, both as to its structure and operation, from the accompanying drawings, taken in conjunction with the accompanying description. Several embodiments of the assembly may be presented herein. It should be understood that various components, parts, and features of the different embodiments may be combined together and/or interchanged with one another, all of which are within the scope of the present application, even though not all variations and particular embodiments are shown in the drawings. It should also be understood that the mixing and matching of features, elements, and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that the features, elements, and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless otherwise described. 
     The system of the present application is configured to translate within an oil/gas well. The plunger lift assembly is configured to translate up and down through a well by selectively permitting the passage of hydrocarbons, contaminants, and liquids through an internal chamber. At the bottom of the well, the plunger assembly is configured to impact a stop or bumper. The impact forces are transferred through a cage to the body. The plunger assembly includes the cage surrounding an internal clutch, a clutch retainer, and a stem. The stem extends from a lower end of the cage during the fall through the well. In this orientation, hydrocarbons, liquids and contaminants are configured to pass around the stem and through channels in the cage into the internal chamber of a mandrel. This passage of fluid permits the plunger to fall through contaminants and liquid in the well. Upon contact at the designated location, the orientation of the stem changes within the cage. The stem presses up within the cage and contacts a bottom portion of the mandrel, thereby forming a seal and preventing the future passage of liquid and contaminants through the internal chamber. In this sealed condition, pressure builds up beneath the plunger which eventually reaches a level where the pressure lifts the plunger to the surface. At the same time, the liquid and contaminants above the plunger are also brought to the surface. The stem is unseated upon contact with the surface of the well. 
     Referring now to the figures wherein like reference characters identify corresponding or similar elements in form and function throughout the several views. The following Figures describe assembly/system  101  and its associated features. 
     Referring now to  FIG. 1  in the drawings, an exploded perspective view of plunger assembly  101  is illustrated. Assembly  101  includes a mandrel  103 , stem  105 , clutch assembly  107 , clutch retainer  109 , and cage  111 . Cage  111  is configured to couple to an end of mandrel  103  in a threaded relationship. Cage  111  and mandrel  103  are detachable. When coupled, cage  111  and mandrel  103  form the body of assembly  101 . Stem  105  is configured to translate within cage  111  between at least two positions, outside of mandrel  103 . Stem  105  is configured to selectively regulate the flow of working fluid through mandrel  103  by changing its position within cage  111 . Clutch assembly  107  is internally located within cage  111  along with stem  105 . Clutch assembly  107  is configured to engage a portion of stem  105  while in both the first position and the second position. Each part is described in further detail in the following figures. 
       FIG. 2  illustrates a partial side section view of the individual parts of assembly  101 . From  FIG. 2 , an internal view of cage  111  is more clearly seen. When assembled, each part is located as illustrated in  FIGS. 3 and 4 . In particular, the two positions of stem  105  are illustrated in  FIGS. 3 and 4 . Also of note is the particular location of clutch retainer  109 . Clutch retainer  109  is located internally within cage  111 . In particular, cage  111  is the lowest part of assembly  101 . Clutch assembly  107  is configured to nestle against a lower internal lip of cage  111  within a formed pocket of space. Clutch retainer  109  is in threaded attachment with cage  111  and is located above clutch assembly  107 . Therefore, clutch assembly  107  is pressed down onto the lower internal lip of cage  111  by the tightening of clutch retainer  109 .  FIGS. 3 and 4  more clearly illustrate the location of clutch retainer  109 . In this embodiment, clutch retainer is clearly internally housed within cage  111  and is not subjected to direct contact with external objects in the well, such as a bumper. By avoiding direct contact with a bumper at the bottom of the well, the life of the clutch is preserved. Impact forces are absorbed by cage  111 . 
       FIGS. 3 and 4  are used to illustrate assembly  101  combined and in operation with stem  105  oriented between two different positions. As noted previously, when assembly  101  is traveling down through a well, stem  105  is naturally in a protruding position such that stem  105  is in a first position as seen in  FIG. 4 . The lower part of the head portion of stem  105  is resting on, or slightly above, clutch retainer  109 . Hydrocarbons, liquids and contaminants within the well are passed through various channels or gaps within assembly  101 , such as those formed in cage  111  to permit the passage of working fluid through internal chamber  115  of mandrel  103 . 
       FIG. 3 , in particular, illustrates stem  105  in the second position, wherein stem  105  is pressed against mandrel  103  by contact with an external member in the well. The transition to the second position occurs when assembly  101  impacts the bottom of the well. The impact seats stem  105  in the second position. The impact forces are absorbed predominantly through cage  111 . In the second position, stem  105  is flush with the bottom surface of cage  111  and the upper surface of the head of stem  105  is pressed against a lower portion of mandrel  103 . The contact between mandrel  103  and stem  105  forms a seal that cuts off the flow of fluid through mandrel  103 . Note that the head of stem  105  in  FIG. 3  is above that of various ports  113  located in the side of cage  111 . The sealing effect prevents the passage of fluid through internal chamber  115  and results in a pressure gradient between the liquid above assembly  101  and that of the fluid below assembly  101 . The pressure gradient causes assembly  101  to rise to the surface of the well and simultaneously remove the liquids and contaminants above it. 
     Stem  105  is illustrated as a cylindrical member having a head portion at an upper end. The shape and size of stem  105  is adapted to fit the sizing of assembly  101 . Some embodiments may utilize various types of surface treatments along the main shaft of stem  105 , such as threads or axial grooves to assist in the passing of solids across the clutch, however in the preferred embodiment, the main shaft of stem  105  is slightly textured as opposed to being relatively smooth. 
     Referring now also to  FIGS. 5-8  in the drawings, clutch assembly  107  is illustrated. Clutch assembly  107  includes a clutch  117  illustrated in  FIG. 5 , a band  118  as seen in  FIGS. 6A and 6B , and a ring  117  shown in  FIG. 7 . Clutch  117  is configured to engage the outer surface of stem  105  around the elongated shaft. Clutch  117  is a multi-member clutch wherein clutch  117  is partitioned into a plurality of radial portions. The portions are equally sized and spaced to permit equal surface contact with stem  105 . Together, the members of clutch  117  surround and contact the circumference of stem  105 . Clutch  117  is configured to permit a greater area of contact with stem  105  for a better transitioning as stem  105  transitions between the first and second positions. Although clutch  117  is shown having three members, it is contemplated that clutch  117  may include more or less members. Additionally, the members may be unequally sized in other embodiments as desired. 
     The respective positioning and orientation of the members of clutch  117  are held together through one or more retainers. The retainers are used to maintain the alignment and orientation of clutch  117 . As seen in  FIG. 7 , clutch assembly includes ring  119 . Ring  119  is configured to clip around a portion of clutch  117  to restrict the ability of each member of clutch  117  from separating from one another. Clutch  117  includes an upper and lower recessed groove  114  located around the circumference of the external surface of each member of clutch  117 . Ring  119  is configured to rest within groove  114 . Ring  119  is configured to protrude away from the outer surface  120  of clutch  117 . The protruding rings  119  help to maintain the alignment of clutch  117  relative to cage  111 . Rings  119  may contact internal surfaces of the cage within the seat which clutch  117  resides. It is understood that ring  119  is not limited to the specific depictions of  FIG. 7 . Ring  119  may be formed as a complete circle, without a gap, in other embodiments. The groove depth for rings  119  can be cut deeper or shallower on the exterior of clutch  117  to control external pressure applied to stem  105 . The depth of the grooves regulates the external pressure on stem  105 . Regulation of external pressures on stem  105  may also be accomplished through the use of different types of rings  119 . 
     In  FIGS. 6A and 6B , bands  118  are illustrated. Bands  118  are configured to wrap around a central body of the clutch members between grooves  114 . An example of bands  118  are Hoopster bands. Bands  118  are bound between rings  119  so as to restrict the ability of bands  118  from sliding off clutch  117 . Bands  118  are configured to provide additional strength and resistance to undesired movement of the members of clutch  117 . In this way, bands  118  are configured to also maintain the alignment and orientation of the individual members of clutch  117 . One or more bands  118  may be used depending on the size of each band. A slot  116  is maintained in each band to ensure appropriate flexure of band  118  and may also allow band  118  to possibly expand sufficiently to pass over the body of clutch  117  if rings  119  are engaged.  FIG. 8  illustrates a side view of clutch  117  with phantom lines representing interior edges. 
     As mentioned previously, it is desired to regulate external pressures on stem  105 . To accomplish this, clutch  117  may be configured to be a variable pressure clutch system through the use of different types of bands  118  and rings  119 . The rings and bands of clutch  117  may be constant section rings, low load unobtrusive bands, and even elastomeric bands that fit on the outer parts of clutch  117  between the grooves. One or more dissimilar styles may be used simultaneously. Clutch  117  may optionally include an elastomeric band layered over bands  118  and/or ring  119 . The mixing and matching of different bands  118  and rings  119  in one or more layers selectively allows for clutch  117  to accommodate and regulate varied external pressures on stem  105 . 
     Referring now also to  FIGS. 9 and 10  in the drawings, clutch retainer  109  is illustrated. Retainer  109  is configured to be located and secured within cage  111 . Retainer  109  is located and seated above clutch assembly  107 . Retainer  109  may be secured in various different ways. As depicted in the Figures, threaded engagement is one such method. This allows for the removal of retainer  109 . Another method is to a pin that passes through a portion of cage  111  and retainer  109  that is also spot welded to cage  111  to prevent undesired removal. The weld prevents the backing out of the pin. When using a pin, retainer  109  would be torqued down to the desired level and then a hole would be drilled through cage  111  and into a portion of retainer  109 . The spot weld would be done after inserting the pin into the hole and ensuring it passes through into retainer  109 . Stem  105  is configured to pass through a central portion  124  of retainer  109 . It is noted that retainer  109  is internally located within cage  111  and is protected from direct impact from the falling of plunger assembly  101  in the well. If in the event of failure of assembly  101 , the internally mounted retainer  109  and clutch assembly  107  remain within cage  111  and are prevented from falling out into the well. This prevents the need to fish the parts out of the well. 
     Referring now also to  FIGS. 11-13  in the drawings, cage  111  is further illustrated. Cage  111  is shown in a perspective view (see  FIG. 11 ) and in a side section view (see  FIG. 12 ). Threaded locations are seen for attachment of cage  111  to mandrel  103  at an upper portion, and a threaded location at a lower portion for attachment with retainer  109 . Cage  111  is a one piece member and is configured to retain thicker walls so as to absorb the impact forces at the bottom of the well without incurring damage. Cage  111  has a gradual taper from an upper end, in communication with the mandrel, that slowly narrows down to a lower end opposite the upper end. The taper is configured to maintain a linear reduction in surface area from the upper end to the lower end of cage  111 . This linear reduction permits for an increased thickness to assist in absorbing impact forces at the bottom of the well. 
     As noted previously, working fluid is configured to enter cage  111  through ports  113  and pass through internal chamber  115 . As working fluid passes between the walls of the well and assembly  101 , particulates may build up resulting in some restriction in flow through ports  113 . Cage  111  is configured to include one or more flow cuts  121  formed into an outer surface of cage  111 . Ports or slots  113  are located on flats or flow cuts  121 . The object and purpose of the ports  113  and flow cuts  121  are to permit for the increased flow of liquid through internal chamber  115 . Importantly, the liquid within the well may include contaminants that can build up and have differing sized dimensions. The use of flow cuts  121  can provide a larger area for the passage of contaminants. This reduces the chances of having to fish out the plunger from the well due to failed operations of the stem in not sealing. The ports  113  and flow cuts  121  are possible because of the thickened walls of cage  111 . The thicker walls also help with absorbing impact forces as noted above. It is understood that one or more ports  113  and or flow cuts  121  are possible. 
     Flow cuts  121  are reduced thickness areas in the wall of the cage. As seen in greater detail in  FIG. 13 , exemplary designs of flow cuts  121  are illustrated and contemplated for use with assembly  101 . Flow cuts  121  are equally spaced around the circumference of cage  111 . Flow cuts  121  are configured to increase the distance between cage  111  with ports  113  and that of the walls of the well so as to minimize chances of restrictions and to increase flow of working fluid through ports  113 . Although flow cuts  121  are illustrated as flat surfaces, it is understood that the contour may be modified to include one or more radiused surfaces. 
     The current assembly has many advantages over the prior art including at least the following: 1) three-piece clutch for added contact points with the stem; 2) an internally located clutch and clutch retainer within the cage; 3) inclusion of thicker walls within the cage; 4) inclusion of flow cuts in the outer surface of the cage; 5) Variable pressure clutch assembly; and 6) multiple bands used around the clutch. 
     The particular embodiments disclosed above are illustrative only, as the application may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. It is therefore evident that the particular embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the description. It is apparent that an application with significant advantages has been described and illustrated. Although the present application is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof.