Patent Publication Number: US-11028661-B2

Title: Fishing neck for plunger

Description:
BACKGROUND 
     Plunger lift systems are used in oil and gas wells when the bottom hole pressure decreases to a point it cannot effectively lift fluids to the surface. A plunger, which is a piston-like object, is placed inside the production tubing. Through use of the s pressure of the well, plungers move up the tubing to lift the fluids to the surface. A valve at the surface when closed causes the pressure to build so that when opened, the plunger rises to the top carrying the fluids to the surface. The plunger returns to the bottom when the valve is closed. The return velocity may be increased using a bypass plunger, where a valve inside the plunger is opened allowing fluid to flow through the center of the plunger. 
     Because plungers are not attached to surface equipment, they are generally provided with a fishing neck to facilitate retrieval should the plunger become stuck in the well. The fishing neck provides an area on which fishing tools can latch. Fishing tools often include an arrangement of collets that can pass over an upper portion of a tool and then spring inwardly to grasp the tool. Some fishing necks are hollow to accommodate a shock absorber for absorbing impact forces to a shift rod of the plunger. Most fishing necks maximize the area that may receive the jaws of the fishing tool. This has led to fishing necks being designed with a thin wall section extending around the circumference of the fishing neck. 
     In a plunger system, a bumper is provided at the top and bottom of the wellbore to absorb energy of the plunger as it travels up and down the tubing. Nevertheless, the repeated contact of the fishing neck with the top bumper can cause the thin walled area of the fishing neck to fatigue and fail. 
     A need exists for an improved fishing neck with a strengthened sidewall, but which still provides quick and easy access to retrieve the plunger using conventional fishing tools. It is to such an apparatus that the inventive concepts disclosed herein are directed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of a plunger lift system for removing fluid from a well bore illustrating a plunger at the bottom of the well bore. 
         FIG. 2  is a sectional view of the plunger lift system of  FIG. 1  illustrating the plunger at the top of the well bore. 
         FIG. 3  is a perspective view of the plunger with a fishing neck constructed in accordance with the inventive concepts disclosed herein connected thereto. 
         FIG. 4  is a perspective view of the fishing neck. 
         FIG. 5  is an elevational view of the fishing neck of  FIG. 4 . 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 4  with a plug removed. 
         FIG. 7  is a sectional view taken along line  7 - 7  of  FIG. 5 . 
         FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 3  illustrating the fishing neck connected to the plunger. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The inventive concepts disclosed are generally directed to a fishing neck for a plunger that includes a head portion, a neck portion, a lower portion, and a plurality of ribs. The head portion has a cylindrical configuration with an outer peripheral surface and an outer diameter. The neck portion has a cylindrical formation with an outer peripheral surface and an outer diameter, which is less than the outer diameter of the head portion. The neck portion extends from the head portion. The lower portion extends from the neck portion and is opposite the head portion. The lower portion has an outer diameter greater than the outer diameter of the neck portion and is connectable to a plunger. The plurality of ribs project from the outer peripheral surface of the neck portion and extend helically from the head portion to the lower portion. 
     In another version, the inventive concepts disclosed are directed to a fishing neck in combination with a plunger which has an upper end and a lower end. The fishing neck has a head portion, a neck portion, and lower portion, and a plurality of ribs. The head portion has a cylindrical configuration with an outer peripheral surface and an outer diameter. The neck portion has a cylindrical configuration with an outer peripheral surface and an outer diameter less than the outer diameter of the head portion. The neck portion extends from the head portion. The lower portion extends from the neck portion and is opposite the head portion. The lower potion has an outer diameter greater than the outer diameter of the neck portion. The lower portion is connected to a plunger. A plurality of ribs project from the outer peripheral surface of the neck portion and extend helically from the head portion to the lower portion. 
     Before explaining at least one embodiment of the inventive concepts disclosed herein in detail, it is to be understood that the inventive concepts are not limited in their application to the details of construction and the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. The inventive concepts disclosed herein are capable of other embodiments, or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting the inventive concepts disclosed and claimed herein in any way. 
     In the following detailed description of embodiments of the inventive concepts, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. However, it will be apparent to one of ordinary skill in the art that the inventive concepts within the instant disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the instant disclosure. 
     As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements, and may include other elements not expressly listed or inherently present therein. 
     Unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B is true (or present). 
     In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments disclosed herein. This is done merely for convenience and to give a general sense of the inventive concepts. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. 
     As used herein, qualifiers like “substantially,” “about,” “approximately,” and combinations and variations thereof, are intended to include not only the exact amount or value that they qualify, but also some slight deviations therefrom, which may be due to manufacturing tolerances, measurement error, wear and tear, stresses exerted on various parts, and combinations thereof, for example. 
     Finally, as used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     Referring now to the drawings, and in particular to  FIGS. 1 and 2 , a plunger lift system  10  for removing fluid, such as oil and water, from a well bore  12  is schematically illustrated. The well bore  12  is shown to be lined with a casing  14  extending downwardly from a wellhead  15 . The casing  14  provides a permanent borehole through which production operations may be conducted. The casing  14  is affixed in the well bore  12  in a conventional manner, such as by cement (not shown), and is provided with perforations  16  open to a producing subterranean formation (also not shown). 
     The plunger lift system  10  includes a tubing string  18 , a plunger  20 , a bottom bumper  22 , a lubricator  23  with a top bumper  24 , and a control valve  26 . The tubing string  18  provides fluid communication between the producing subterranean formation and the surface such that a reservoir fluid (not shown), for example water and/or oil and/or natural gas, is produced through the tubing string  18 . The casing  14  and the tubing string  18  define an annulus  19 , which also provides fluid communication through the well bore  12 . 
     The plunger  20  is illustrated as being a sliding sleeve plunger. However, it will be appreciated that the inventive concepts disclosed herein are also applicable to other types of plungers. The plunger  20  is dropped into the tubing string  18 . When the control valve  26  is closed, pressure is allowed to build so when the control valve  26  is opened, the plunger  20  rises to the top carrying the fluids to the surface. The plunger  20  returns to the bottom when the control valve  26  is closed. Through operation of the control valve  26 , a liquid slug is cyclically brought to the surface of the wellbore  12  from stored gas pressure. In the off cycle, the plunger  20  falls and pressure builds again in the wellbore  12 . 
     As described above, plungers are free pistons unattached to surface equipment. As such, they are generally provided with a fishing neck to facilitate retrieval should the plunger become stuck in the wellbore. The fishing neck provides an area on which fishing tools can latch. Fishing tools often include an arrangement of collets that can pass over an upper portion of a tool and then spring inwardly to grasp the tool. Most fishing necks maximize the area that may receive the jaws of the fishing tool. This has led to fishing necks being designed with a thin wall section extending around the circumference of the fishing neck. The repeated contact of the fishing neck with the upper bumper spring can cause the thin walled area of the fishing neck to fatigue and fail. 
     Referring now to  FIGS. 3 and 8 , a fishing neck  30  constructed in accordance with the inventive concepts disclosed herein is shown connected to the plunger  20 . In one embodiment, the plunger  20  has a sleeve  32  and a rod  34 . The sleeve  32  may be ribbed. The rod  34  has an upper end  35  ( FIG. 8 ) and a lower end  36 . The rod  34  is slidable relative to the sleeve  32  between a down position ( FIGS. 3 and 8 ) and an up position (not shown). In the down position, a flow path through the sleeve  32  is open allowing fluid to flow through the sleeve  32  as the plunger  30  is returning to the bottom of the wellbore  12 . In the up position, the lower end  36  of the rod  34  closes the flow path allowing the plunger  30  to lift fluid to the surface as the plunger  30  is rising to the top of the wellbore  12 . 
     In a manner to be discussed below with reference to  FIG. 8 , the fishing neck  30  is connected to the upper end  35  of the rod  34 . The rod  34  is moved between the down position and the up position by engagement with the bottom bumper  22  and the top bumper  24 . Contact of the lower end  36  of the rod  34  with the bottom bumper  22  causes the rod  34  to move from the down position to the up position. Contact of the fishing neck  30  with the top bumper  24  causes the rod  34  to move from the up position to the down position. 
     Referring to  FIGS. 4-8 , the fishing neck  30  includes a head portion  40 , a neck portion  42 , and a lower portion  44 . The head portion  40  has a cylindrical configuration with an outer peripheral surface  46  and an outer diameter. An upper edge  47  of the head portion  40  may be beveled. The neck portion  42  extends from the head portion  40  and has a cylindrical configuration with an outer peripheral surface  48  and an outer diameter, which is less than the outer diameter of the head portion  40  to form a shoulder  48 . The lower portion  44  extends from the neck portion  42  and has an outer diameter greater than the outer diameter of the neck portion  42 . As will be described below, the lower portion  44  is connectable to the plunger  20 . 
     The fishing neck  30  has a plurality of ribs  50  projecting from the outer peripheral surface  49  of the neck portion  42 . The ribs  50  are spaced apart and extend helically from the head portion  40  to the lower portion  44  so as to form slots  52  between the ribs  50 . Each of the ribs  50  is coextensive with a portion of the outer peripheral surface  46  of the head portion  40  so the ribs  50  are at least flush with the outer peripheral surface  46  of the head portion  40 . The ribs  50  may also be coextensive with a portion of an outer peripheral surface  54  of the lower portion  44 . In one embodiment, the fishing neck  30  has three ribs  50  equally spaced circumferentially about the neck portion  16  ( FIG. 7 ). It will be appreciated that the number of ribs is not limited to three, but may be varied. 
     The ribs  50  are spaced and angled such that collets (not shown) of a fishing tool may be received between the ribs  50 . The helical configuration of the ribs  50  allows the collets to slide longitudinally down the fishing neck  30  with assurance that the collets will slide off the ribs  50  and into the slots  52  formed by the ribs  50  without requiring the collets to be rotated. In one embodiment, an upper end of the ribs  50  is longitudinally aligned with a lower end of an adjacent rib  50 . The ribs  50  may be fabricated to have a depth of about 0.175 inches and a width of about 0.25 inches. The ribs  50  may be rotated so where one rib  50  extends from the head portion  40 , an adjacent rib  50  extends from the lower portion  44  in longitudinal alignment. By way of example, when the fishing neck  30  includes three ribs  50 , the ribs are equally spaced and each of the ribs  50  may be rotated 120 degrees. 
     As shown in  FIG. 6 , the fishing neck  30  may have a bore  60  extending through the head portion  40 , the neck portion  42 , and the lower portion  44 . The bore  60  has a threaded portion  62  in the head portion  40  for receiving a plug  64  ( FIGS. 4 and 8 ). The bore  60  has an internal shoulder  66  at the lower portion  44 . 
       FIG. 8  is a sectional view illustrating the fishing neck  30  connected to the plunger  20 . The upper end  35  of the rod  34  of the plunger  20  is inserted into the bore  60 . In one embodiment, a fastener  70 , such as a nut, may be threadingly connected to the upper end  35  of the rod  34  so the fastener  70  is engagable with the interior shoulder  66  of the lower portion  44 . The fastener  70  may be welded or otherwise permanently affixed to the rod  34 . 
     A shock absorber  72  is positioned adjacent to the upper end  35  of the rod  34 . The shock absorber  72  may be tubular or cylindrical member fabricated of an elastomeric material, such as rubber. The shock absorber  72  is secured in the bore  60  with the plug  64  so the shock absorber  72  is interposed between the plug  64  and the upper end  35  of the rod  34 . The shock absorber  72  absorbs the impact force to the rod  34  upon impact of the fishing neck  30  with the top bumper  24 . 
     From the above description, it is clear that the inventive concepts disclosed herein are well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the inventive concepts disclosed herein. While exemplary embodiments of the inventive concepts disclosed herein have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the scope of the inventive concepts disclosed and as defined in the appended claims.