Abstract:
A device for removing and installing a plunger in a well head has a elongate rigid tube with a magnetic connector mechanism at it distal end for engaging the plunger during removal and installation of the plunger. A longitudinal opening or passage can be provided extending the entire longitudinal length of the rigid tube and magnetic connector mechanism. An elongate rod is positioned in the opening or passage so that the upper end of the rod can be moved downwardly to eject the lower end of the rod from the magnetic connector mechanism to thereby disconnect an attached plunger from the magnetic connector mechanism.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to apparatus, commonly referred to as retrievers, used in removing and installing plungers in the well head of a hydrocarbon producing well. More specifically the invention relates to such apparatus that employ a magnetic latching mechanism for engaging the plunger in both removing the plunger from a well and replacing a plunger in a well. 
     2. State of the Art 
     A plunger lift is an apparatus that is used commonly in the oil and gas industry to increase the productivity of oil and gas wells. Descriptions of the use of such plunger lifts are well described in the following U.S. Pat. Nos. 2,661,024; 6,719,060; 6,935,427; and 7,383,878. As explained in these patents, a plunger is designed to intermittently drop to the bottom of a well and then rise to the top carrying well liquids out of the well that would otherwise collect at the bottom of the well and thus decrease the efficiency of the operation of the well. 
     When the plunger rises to the top of the well it is retained in a receiver near the well head until it is to be dropped back down the well. The receiver is also commonly called a lubricator. The plunger requires recurrent maintenance and periodic replacement which requires that the plunger be repeatedly removed from the receiver or lubricator. This is done by taking a cap off the well head and using a retriever apparatus to reach down into the receiver or lubricator and retrieve the plunger through the open end of the well head. 
     Retrievers have been used that employ different mechanical means to attach to the upper end of the plunger in able to pull the plunger up and out of the well head. These mechanical connectors often employ collets, fingers or other projections that catch an engagement means on the upper end of the plunger. The retrievers are carried from well to well in the back of a truck of the person servicing the well, and the collets, fingers or other projections are subject to being broken and bent to where they are unusable. Further dirt and grime can accumulate in the fingers and projections again rendering them inoperable at least until they are thoroughly cleaned. 
     A retriever has been used that employs a magnetic connection between the distal end of the retriever and the plunger. In  FIG. 1  there is shown a longitudinal cross-sectional view through such a retriever that is currently being used and which uses a magnetic connection with the plunger. As shown in  FIG. 1 , the prior art retriever comprises an elongate, solid handle  10  that is cylindrical in shape, i.e., has a round transverse cross-section. The handle  10  is made of aluminum. A block  11  of polymeric material such as polyethylene is press fit onto the distal end of the handle  10 . A bore  12  is formed inwardly from the distal end of the block  11 , and a magnet  13  is received in that bore  12 . The magnet  13  is itself press fit into a brass ring  14 , which in turn is press fit into a steel ring  15 , with the assembled magnet  13 , and rings  14  and  15  being press fit as a unit into the bore  12  of the block  11  at the distal end of the handle  10 . A series of grooves  16  are formed near the proximal end of the handle  10  as means for firmly grasping the handle  10 . 
     In the device of the prior art as shown in  FIG. 1 , the face  18  of the magnet  13  is exposed and subject to being impacted at its exposed face by other tools and so forth as it is being transported in the bed of a truck from one well to another. The magnet  13  is very brittle and subject to being broken by such impacts on the exposed face  18  of the magnet  13 . To minimize impact of the magnet  13  with the plunger when the retriever is being used, the block  11  is provided with a circular, projecting lip  17  from the face  18  of the magnet  13  at the perimeter of the block  11 . 
     In use, that lip  17  can be worn away or broken away which can result in the plunger impacting the magnet  13  when the retriever is lowered into the well head to retrieve the plunger. Again, the magnet  13  is very brittle and it is imperative that the magnet  13  is not chipped or broken such that pieces of the magnet  13  get dropped into the well. Thus, care must be exercised to insure that there has been no damage to the lip  17  whenever the retriever is used. 
     When the lip  17  is in proper, undamaged condition, the stand-off space created between the plunger and the magnet  13  by the lip  17  decreases the lifting power of the retriever. Another problem associated with the existing magnet retriever is its inability to readily let go of the plunger when inserting the plunger through the well head into the receiver of the well. The magnetic retriever of the prior art as shown in  FIG. 1  has to be vigorously shaken to disengage the plunger from the magnetic connection. That risks damaging the plunger and the receiver or lubricator of the well when the plunger drops when it breaks magnetic connection to the retriever. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, an improvement is made in a retriever device using a magnetic connection between the retriever and the plunger. The improved magnetic retriever device is used for alternatively removing and installing a plunger in a receiver located at the well head of a hydrocarbon producing well, and the invention also includes a novel method of using the retriever to install a plunger in the receiver of the well. 
     The device of the present invention comprises a straight, elongate, rigid member having a metallic mounting block integrally attached to a distal end of the rigid member. The proximal end of the mounting block is attached to the distal end of the rigid member, and the mounting block further has a proximal end, with a side wall connecting the distal and proximal ends thereof. The mounting block has a bore that extends inwardly from its distal end, and a magnet is fit snugly in the bore in the mounting block. 
     A metallic cup member is provided for securely retaining the magnet within the bore of the mounting block as well as to provide a means of preventing impacts of any object directly against the otherwise open face of the magnet. There is no chance that pieces of the magnet can be chipped off or broken therefrom and fall into the well. The cup has a side wall that extends from the perimeter of an end wall, whereby the side wall forms an otherwise open end of the cup member. The otherwise open end of the cup is press fit over the distal end of the mounting block. 
     To achieve a secure, tight press fit of the side wall of the cup member with the distal end of the mounting block, the side wall of the cup member has an internal face that has a circumferential shape corresponding to an outer circumferential shape of the side wall of the mounting block. In addition, the internal face of the side wall of the cup member has a circumferential dimension that is slightly less than corresponding circumferential dimension of the side wall of the mounting block, so that the side wall of the cup member makes a tight, secure, press fit around the side wall of the mounting block. The magnet is thus permanently retained tightly in the bore of the mounting block. 
     The rigid member, the mounting block and the cup member, of course, have circumferential dimensions that will allow the retriever device to be inserted longitudinally into the well head and receiver of the well. 
     In preferred embodiments of the invention novel means are provided for easy, reliable disengagement of the plunger from the magnet when the plunger is being installed in the receiver of the well head. In those embodiments, a mechanical disengagement of the plunger is achieved that does not involve shaking or other sudden movement of the retriever to disengage the plunger from the magnetic connection at the end of the retriever. In the preferred embodiments, a longitudinal, central bore is provided from the proximal end of the rigid member to the distal end thereof. 
     A push rod is positioned in the continuous bore of the retriever device for longitudinal movement back and forth in that continuous bore. The push rod has its proximal end extending from the proximal end of the rigid member of the retriever device. Means are provided for restricting the longitudinal movement of the push rod back and forth inside the rigid member, and the lower end portion of the push rod is further mechanically linked to appropriate mechanical means for disengaging the plunger from the magnet and thereby readily and safely releasing the plunger from the magnet on the retriever device when the plunger is being installed in its proper place in the receiver or lubricator of the well. 
     In installing a plunger into the well, the distal end of the push rod is contained within the bore of the retriever, and the plunger is attached at its upper end to the magnet on the distal end of the retriever device. The plunger and retriever are introduced longitudinally into the well through the well head until the plunger is in its desired position in the receiver or lubricator. At that point, the push rod and rigid member are moved relative to each other so as to activate the means for disengaging the plunger from the magnet at the end of the retriever device. The plunger is thus gently but firmly released from its magnetic connection to the retriever device, and there is no chance of the plunger being dropped into the receiver or lubricator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  (prior art) is a longitudinal cross-sectional view of a prior art retriever device that utilizes a magnet to attach the plunger to the distal end of the retriever; 
         FIG. 2  is a longitudinal cross-sectional view of an improved magnetic retriever in accordance with the present invention; 
         FIGS. 3 through 7  are partial longitudinal cross-sectional views of five similar but slightly different embodiments of the retriever in accordance with the present invention, with the cross-sectional views being taken along line  3 - 3  of  FIG. 2 ; and 
         FIGS. 7 and 8  are a cross-sectional views taken along line  7 - 7  of  FIG. 2 , line  8 - 8  of  FIG. 5 , respectively. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various preferred embodiments of the retriever device of the present invention for alternatively removing and installing a plunger in a receiver located at the well head of a hydrocarbon producing well in accordance with the present invention are shown in  FIGS. 2 through 8  of the drawings. In the drawings, the same reference numbers designate the same elements having the same basic functions in each of the various embodiments. 
     As illustrated, the device comprises a straight, elongate, rigid, cylindrical tube  20  having a round exterior periphery, and a longitudinal opening  21  extends from a proximal end  23  of the rigid tube  20  to a distal end  22  of that tube  20 . A metallic mounting block  24 , having a distal end  25  and a proximal end  26 , is securely attached at its proximal end  26  to the distal end  22  of the rigid tube  20  by appropriate means that will be described in more detail hereinafter. A cylindrical side wall  27  forms the outer periphery of the mounting block  24 , with the side wall  27  extending between the distal end  25  and proximal end  26  of the mounting block  24 . 
     A first bore  29  extends inwardly from a distal end  25  of the mounting block  24 . The bore  29  is, of course, circular in shape, and any reference to a bore in this specification will also be one having a circular shape. The center axis of the first bore  29  is in substantially longitudinal alignment with a center axis of the longitudinal opening  21  in the rigid tube  20 . 
     The circular-shaped first bore  29  forms a cavity which receives a circular-shaped magnet  30  therein. The magnet  30  has a substantially circular perimeter that is received snugly in the first bore  29 , with the inner face of the magnet  30  abutting the inner end of the first bore  29 . The magnet  30  is sized such that it is received in its entirety within the first bore  29 . 
     A second bore  31  extends inwardly from a proximal end  26  of the mounting block  24 . The second bore  31  is in substantially longitudinal alignment with the center axis of the longitudinal opening  21  in the rigid tube  20 . The second bore  31  extends inwardly to meet with and join the first bore  29 , so that an inner end of the second bore  31  opens into the inner end of the first bore  29 . The magnet  30  retained in the first bore  29  abuts the inner end of the second bore  31 . A third bore  32  extends through magnet  30 , with the third bore  32  being in substantially longitudinal alignment with the longitudinal opening  21  in the rigid tube  20 . The third bore  32  is also in substantially longitudinal alignment with the first and second bores  29  and  31  of the mounting block  24 . 
     A metallic cup member  33  is provided to encapsulate the perimeter sides and distal end of the mounting block  24 . The metallic cup member  33  has a substantially planar end wall  34 , with a peripheral side wall  35  extending from the perimeter of the end wall  34  in a direction substantially perpendicular to the end wall  34 . The free, distal end of the side wall  35  terminates in an otherwise open end of the cup member  33  facing away from the substantially planar end wall  34  of the cup member  33 . A central opening  38  having a substantially circular shape is provided in the planar end wall  34  of the cup member  33 . The central opening  38  has a diameter that is at least the same as the diameter of the third bore  32  in the magnet  30 . Preferably, the diameters of the central opening  38  and the third bore  32  are substantially identical, with the central opening  38  and the third bore  32  being in substantially coaxial alignment so that adjacent peripheral edges of the third bore  32  and the central opening  38  lie in abutting, side-by-side relationship with each other. Accordingly, the central opening  38  opens directly into the third bore  32 . 
     The peripheral side wall  35  of the cup member  33  has an internal face that has a circumferential shape corresponding to an outer circumferential shape of the outer side wall  27  of the mounting block  24 . The internal surface of the peripheral side wall  35  of the cup member  33  has a circumferential dimension that is slightly less than the corresponding circumferential dimension of the outer side wall  27  of the mounting block  24 . Preferably, the circumferential dimension of the internal surface of the side wall  35  of the cup member  33  is between about 0.004% and 0.0045% less than the corresponding circumferential dimension of the side wall  27  of said mounting block  24 . The side wall of the cup member  33  is press fit around the outer side wall  27  of the mounting block  24  thereby permanently retaining the magnet tightly in the first bore  29  of the mounting block  24 . 
     A straight, elongate rod  36  is positioned for longitudinal movement in the rigid tube  20 . The rod  36  has a proximal end  37  that projects outwardly from the proximal end  23  of the rigid tube  20 . Means are provided for restraining the longitudinal movement of the rod  36  in the rigid tube  20  so that when the proximal end  37  of the rod  36  moves toward the proximal end  23  of the rigid tube  20 , the distal end  39  of the rod  36  moves from a first position in which it is located at least inwardly of an outer face of the planar end wall  34  of the cup member  33  to a second position extending outwardly by at least about 1 cm from said outer face of the planar end wall  34  of the cup member  33 . 
     The means for restraining the longitudinal movement of the rod  36  advantageously comprises a relatively short slot  41  that is formed in the side wall of the rigid tube  20  as shown in  FIGS. 2 and 7 . The center axis of slot  41  is substantially parallel with a center axis of the longitudinal opening  21  in the rigid tube  20 . A transverse opening  42  (see  FIG. 7 ) extends substantially diametrically into the rod  36 . A pin  43  is received in the transverse opening  42 , with an outer end of the pin  43  projecting outwardly from the transverse opening  42  into the slot  41  in the rigid tube  20 . The longitudinal movement of the rod  36  is thus restrained to the movement of the pin  43  back and forth in the slot  41 . 
     Means are also provided for returning the rod  36  from its second position back to its first position. In one embodiment, a knob  46  is attached at the proximal end of the rod  36 , with the knob  46  having a peripheral dimension that is greater than a corresponding peripheral dimension of the rod  36 . A coil spring  47  is positioned around the distal end of the rod  36 , with the spring  47  being located between the proximal end  23  of the rigid tube  20  and the knob  46 . Coil spring  47  biases the rod  36  to automatically return it to its first position when there is no downward force applied to the rod  36 . 
     In a second embodiment of means for returning the rod  36  from its second position to its first position, the actual movement of the rod  36  is done manually rather than being biased by a spring, and means are provided for selectively holding the rod  36  in its second position. In the second embodiment, a side notch  44  can be formed to extend from an end of the slot  41  as shown in  FIGS. 2 and 7 . The side notch  44  projects substantially transverse of the slot  41  at the end of the slot  41  that is closest to the distal end  22  of rigid tube  20 . The side notch  44  forms a detente into which the pin  43  can be positioned to retain the rod  36  in its first position. The rod  36  is moved so that the pin  43  is positioned adjacent to the side notch  44 , and then the rod  36  is rotated so that the pin  43  moves into the side notch  44 . 
     It should be recognized that the notch  44  would be superfluous and not necessary when a coil spring  47  is employed as described above. Vice versa, the coil spring  47  would not be necessary when the notch  44  is used. 
     The rigid tube  20 , the mounting block  24  and the cup member  33  all have circumferential dimensions that will allow the mounting block  24 , the cup member  33  and the rigid tube  20  to be inserted longitudinally into the receiver of a well head of a hydrocarbon producing well. 
     As mentioned previously, means are provided for attaching the proximal end  26  of the mounting block  24  to the distal end  22  of the rigid tube  20 . Two preferred embodiments of such means are disclosed. In the first embodiment as illustrated in  FIG. 3 , the second bore  31  in the mounting block  24  is, of course, cylindrical in shape, and it is provided with internal threads. The distal end  22  of the rigid tube  20  has a cylindrical peripheral shape, and the distal end  22  is provided with external threads that engage the internal threads in the second bore  31  of the mounting block  24 . In this embodiment, the distal end  22  of the rigid tube  20  is threaded completely through the second bore  31  such that the distal end  22  extends to approach but not contact an inner face of the magnet  30 . 
     In the second embodiment as illustrated in  FIG. 4  a counter bore  50  extends inwardly around and along the second bore  31  in the mounting block  24  from the proximal end  26  of the mounting block  24 . The counter bore  50  is, of course, cylindrical in shape, and it is provided with internal threads. The distal end  22  of the rigid tube  20  has a cylindrical peripheral shape, and the distal end  22  is provided with external threads that engage the internal threads in the counter bore  50  of the mounting block  24 . In this embodiment, the counter bore  50  does not extend along the entire length of the second bore  31 , and the distal end  22  of the rigid tube  20  is threaded into the counter bore  50  so that it is firmly and securely held in the counter bore  50 . 
     In all embodiments of the invention, the rigid tube  20  is preferably made of aluminum, the mounting block  24  is preferably made of carbon steel, and the cup member  33  and the rod  36  are both preferably made of stainless steel. Further, means can be provided for firmly grasping the proximal end  23  of the rigid tube  20 . Although not shown in the drawings, the means for grasping the rigid tube  20  can be a series of spaced apart, peripheral indentations formed at the proximal end  23  of the rigid tube  20  in a very similar manner to the series of grooves  16  of the prior art retriever shown in  FIG. 1 . 
     The embodiments of the invention as described heretofore are advantageously used when removing and installing plungers that have a relatively solid upper surface. In using the retriever of such embodiments to remove a plunger from a well head, the distal end  22  of the tube  20  and its associated mounting block  24  and magnet  30  is inserted longitudinally into the well head until the cup member  33  and magnet  30  contact the upper end of the plunger. The tube  20  is then pulled from the well head, and the plunger is readily detached from its magnetic attachment to the magnet  30 . 
     When using the retriever as described heretofore to install a plunger in a receiver located at the well head of a hydrocarbon producing well, the upper end of a plunger is magnetically attached to the cup member  33  and magnet  30 , and the plunger and tube  20  are inserted longitudinally into the well head to position the plunger at a desired position in the receiver at the well head. Then, the proximal end  23  of the rod  20  is pushed downwardly while simultaneously pulling upward on an proximal end  23  of the rigid tube  20  to gently release the plunger from magnetic attachment with the magnet  30 . The tube  20 , with the magnet  30  and the rod  36  are then withdrawn from the well head. 
     Alternative, preferred embodiments of the invention are used when the plunger is of a construction that has an opening located in the center of the plunger. In that situation, the distal end  37  of the rod  36  as shown in the embodiments of  FIGS. 2-4  would not contact the plunger as the rod  36  is moved to its second position extending from the exposed face of the planar end wall  34  of the cup member  33 . One of the alternative embodiments is shown in  FIG. 5 . 
     In the embodiment illustrated in  FIG. 5 , the rigid tube  20 , longitudinal opening  21 , the elongate rod  36 , the mounting block  24 , the magnet  30  and the cup member  33  are all basically the same, with substantially the same functions, as the like numbered elements of the embodiments of  FIGS. 2-4 . The means for restraining the longitudinal movement of the rod  36 , i.e., the slot  41 , the pin  43  and the opening  42  in the rod  36  have the same functions as the same numbered elements of the embodiments as shown in  FIGS. 2-4 , but have been relocated to a position near the distal end  22  of rigid tube  20  and the distal end  39  of the rod  36 . 
     When the rod  36  moves downwardly, a distal end  39  of the rod  36  moves from a first position in which it is spaced inwardly by at least about 1 cm from the proximal end  26  of the mounting block  24  to a second position in which the distal end  39  of the rod  36  at least approaches the proximal end  26  of the mounting block  24 . 
     A disengagement member is provided that comprises a base member  53  that has a central orifice  54  extending there through so that the orifice  54  encircles the rigid tube  20  whereby the base member  53  can move back and forth longitudinally along the rigid tube  20 . A skirt  55  extends from a periphery of the base member  53  so that the skirt  55  surrounds the cup member  33  and can move smoothly back and forth over the surface of the cup member  33  as the base member  53  moves longitudinally back and forth along the rigid tube  20 . 
     Means are associated with the distal end  39  of the rod  36  for moving the disengagement member. Such means comprises positioning the slot  41  near the distal end  22  of the rigid tube  20 , with the pin  43  extending through the slot  41  in the rigid tube  20  so that the pin  43  projects outwardly from an outer surface of the rigid tube  20  and engages a substantially round receiver opening  56  that is provided extending substantially axially into the base member  53  from the orifice  54  in the base member  53 . The pin  43  is received securely in the receiver opening  56  in the base member  53  so that the base member  53  moves back and forth as the pin  43  moves back and forth in the slot  41 . 
     When the distal end  39  of the rod  36  moves toward the distal end  22  of the rigid tube  20 , a distal, exposed end  57  of the skirt  55  projects outwardly away from the outer face of the planar end wall  34  of the cup member  33 . Thereafter, when the distal end  39  of the rod  36  moves back away from the distal end  22  of the rigid tube  20 , the skirt  55  retracts back over the sidewall  35  of cup member  33  so that the exposed end  57  of the skirt  55  does not project from the outer face of the planar end wall  34  of cup member  33 . 
     Although not shown explicitly in  FIG. 5 , it is to be recognized that the magnet  30  of  FIG. 5  could be provided with a bore  32  as shown in the embodiments of  FIGS. 2-4 , and the planar end wall  35  of  FIG. 5  could be provided with a central opening  38  as shown in  FIGS. 2-4 . The distal end  39  of the rod could be extended down into the bore in the magnet so that the distal end  39  projects out through the opening in the cup member  33  when the skirt  55  projects outwardly away from the outer face of the planar end wall  34  of the cup member  33 . 
     The embodiment of the invention shown in  FIG. 5  can be modified slightly as shown in  FIG. 6 . In the embodiment shown in  FIG. 6 , the rod  36  extends through the rigid tube  20  as in the other embodiments of the invention that have previously been described. But, in the embodiment shown in  FIG. 6 , the distal end  39  of the rod  36  is securely attached to the proximal end  26  of the mounting block  24 . As shown in  FIG. 6 , the end  39  is provided with external threads which are received in a threaded bore  60  in the proximal end  26  of the mounting block  24 . The magnet  30  is encapsulated in the mounting block  24  by cup member  33  in the same manner as previously described herein. 
     In the embodiment shown in  FIG. 6 , the distal end  22  of the rigid tube  20  is securely attached to the base member  53  of the disengagement member. The orifice  54  of the base member  53  encircles the rod  36  as described hereinbefore with respect to the embodiment illustrated in  FIG. 5 . The skirt  55  of the disengagement member extends from the periphery of the base member  53  as previously described with respect to the embodiment illustrated in  FIG. 5 . Means for restricting movement of the rod  36  within the rigid tube  20  comprises the short slot  41  in rigid tube  20 . A pin receiving opening  42  is provided in rod  36 , and a pin  43  is positioned in the pin receiving opening  42 , with the pin  43  extending from the rod  36  through the slot  41  in the rigid tube  20 . The rod  36  can move so that the distal end  57  of the skirt  55  will project by at least 1 cm from an outer face of the planar end wall  34  of the cup member  30 . A coil spring  63  can be provided in the space between the proximal end  26  of the mounting block  24  and the base member  53  to bias the base member  53  to a position in which the exposed end  57  of the skirt  55  is withdrawn back over the sidewall  35  of the cup member  33 . 
     When using the embodiment of the invention shown in  FIG. 6 , a plunger is magnetically attached to the magnet  30  and planar end wall  34  of the cup member  33 . The plunger is then positioned in its desired placement in a receiver of a well head as previously described herein. The plunger is then disengaged from the magnet  30  and planar end wall  34  of the cup member  33  by depressing the rigid tube  20  while simultaneously pulling the rod  36  in an opposite direction. The exposed end  57  of the skirt  55  holds the plunger in place while the movement of the rod  36  pulls the magnet  30  and cup member  33  away from the plunger so that the plunger is disengaged from its former magnetic attachment to the magnet  30  and cup member  33 . 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.