Abstract:
A plunger apparatus operates to propel one or more jets of gas through one or more internal orifices and/or nozzles out through an aperture and into a liquid load whereby a transfer of the gas into the liquid load causes turbulent aeration to the liquid load during a plunger rise. This action can boost the carrying capacity of a plunger lift system resulting in improved well production.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a plunger lift apparatus for the lifting of formation liquids in a hydrocarbon well. More specifically, the plunger comprises an internal nozzle apparatus that operates to propel one or more jets of gas through an internal aperture and into a liquid load, transferring gas into the liquid load and causing an aeration of the liquid load during lift. 
   BACKGROUND OF THE INVENTION 
   A plunger lift is an apparatus that is used to increase the productivity of oil and gas wells. Nearly all wells produce liquids. In the early stages of a well&#39;s life, liquid loading is usually not a problem. When rates are high, the well liquids are carried out of the well tubing by the high velocity gas. As a well declines, a critical velocity is reached below which the heavier liquids do not make it to the surface and start to fall back to the bottom, exerting back pressure on the formation and loading up the well. A plunger system is a method of unloading gas in high ratio oil wells without interrupting production. In operation, the plunger travels to the bottom of the well where the loading fluid is picked up by the plunger and is brought to the surface removing all liquids in the tubing. The plunger also helps keep the tubing free of paraffin, salt or scale build-up. 
   A plunger lift system works by cycling a well open and closed. During the open time, a plunger interfaces between a liquid slug and gas. The gas below the plunger will push the plunger and liquid to the surface. This removal of the liquid from the tubing bore allows an additional volume of gas to flow from a producing well. A plunger lift requires sufficient gas presence within the well to be functional in driving the system. Oil wells making no gas are thus not plunger lift candidates. 
   A typical installation plunger lift system  100  can be seen in  FIG. 1 . Lubricator assembly  10  is one of the most important components of plunger system  100 . Lubricator assembly  10  includes cap  1 , integral top bumper spring  2 , striking pad  3 , and extracting rod  4 . Extracting rod  4  can be employed depending on the plunger type. Within lubricator assembly  10  is plunger auto catching device  5  and plunger sensing device  6 . 
   Sensing device  6  sends a signal to surface controller  15  upon plunger  200  arrival at the well top. Plunger  200  can be the plunger of the present invention or other prior art plungers. Sensing the plunger is used as a programming input to achieve the desired well production, flow times and wellhead operating pressures. 
   Master valve  7  should be sized correctly for the tubing  9  and plunger  200 . An incorrectly sized master valve  7  will not allow plunger  200  to pass through. Master valve  7  should incorporate a full bore opening equal to the tubing  9  size. An oversized valve will allow gas to bypass the plunger causing it to stall in the valve. 
   If the plunger is to be used in a well with relatively high formation pressures, care must be taken to balance tubing  9  size with the casing  8  size. The bottom of a well is typically equipped with a seating nipple/tubing stop  12 . Spring standing valve/bottom hole bumper assembly  11  is located near the tubing bottom. The bumper spring is located above the standing valve and can be manufactured as an integral part of the standing valve or as a separate component of the plunger system. The bumper spring typically protects the tubing from plunger impact in the absence of fluid. Fluid accumulating on top of plunger  200  may be carried to the well top by plunger  200 . 
   Surface control equipment usually consists of motor valve(s)  14 , sensors  6 , pressure recorders  16 , etc., and an electronic controller  15  which opens and closes the well at the surface. Well flow ‘F’ proceeds downstream when surface controller  15  opens well head flow valves. Controllers operate on time and/or pressure to open or close the surface valves based on operator-determined requirements for production. Additional features include: battery life extension through solar panel recharging, computer memory program retention in the event of battery failure and built-in lightning protection. For complex operating conditions, controllers can be purchased that have multiple valve capability to fully automate the production process. 
     FIGS. 2 ,  2 A,  2 B and  2 C are side views of various plunger mandrel embodiments. Although an internal mandrel orifice  44  may or may not be present in prior art plungers, such an orifice can define a passageway for the internal nozzle of the present device. Each mandrel shown comprises a male end sleeve  41 . Threaded male area  42  can be used to attach various top and bottom ends as described below in  FIGS. 3 ,  3 A,  3 B and  3 C.
         A. As shown in  FIG. 2B , plunger mandrel  20  is shown with solid ring  22  sidewall geometry. Solid sidewall rings  22  can be made of various materials such as steel, poly materials, Teflon®, stainless steel, etc. Inner cut grooves  30  allow sidewall debris to accumulate when a plunger is rising or falling.   B. As shown in  FIG. 2C , plunger mandrel  80  is shown with shifting ring  81  sidewall geometry. Shifting rings  81  allow for continuous contact against the tubing to produce an effective seal with wiping action to ensure that most scale, salt or paraffin is removed from the tubing wall. Shifting rings  81  are individually separated at each upper surface and lower surface by air gap  82 .   C. As shown in  FIG. 2 , plunger mandrel  60  has spring-loaded interlocking pads  61  in one or more sections. Interlocking pads  61  expand and contract to compensate for any irregularities in the tubing, thus creating a tight friction seal.   D. As shown in  FIG. 2A , plunger mandrel  70  incorporates a spiral-wound, flexible nylon brush  71  surface to create a seal and allow the plunger to travel despite the presence of sand, coal fines, tubing irregularities, etc.   E. Flexible plungers (not shown) are flexible for coiled tubing and directional holes, and can be used in straight standard tubing as well.       
     FIGS. 3 ,  3 A,  3 B and  3 C are side views of fully assembled plungers each comprising a fishing neck ‘A’. Each plunger comprises a bottom striker  46  suited for hitting the well bottom. 
   Recent practices toward slim-hole wells that utilize coiled tubing also lend themselves to plunger systems. With the small tubing diameters, a relatively small amount of liquid may cause a well to load-up, or a relatively small amount of paraffin may plug the tubing. 
   Plungers use the volume of gas stored in the casing and the formation during the shut-in time to push the liquid load and plunger to the surface when the motor valve opens the well to the sales line or to the atmosphere. To operate a plunger installation, only the pressure and gas volume in the tubing/casing annulus is usually considered as the source of energy for bringing the liquid load and plunger to the surface. 
   The major forces acting on the cross-sectional area of the bottom of the plunger are:
         The pressure of the gas in the casing pushes up on the liquid load and the plunger.   The sales line operating pressure and atmospheric pressure push down on the plunger.   The weight of the liquid and the plunger weight push down on the plunger.   Once the plunger begins moving to the surface, friction between the tubing and the liquid load acts to oppose the plunger.   In addition, friction between the gas and tubing acts to slow the expansion of the gas.       

   In some cases, a large liquid loading can cause the plunger lift to operate at a slowed rate. A well&#39;s productivity can be impacted by the lift rate. Thus a heavy liquid load can be a major factor on a well&#39;s productivity. 
   SUMMARY OF THE INVENTION 
   The present apparatus provides a plunger lift apparatus that can more effectively lift a heavy liquid. In short, a heavy liquid load can be brought to the surface at a higher rise velocity. 
   One or more internal orifices allow for a transfer of gas from the well bottom into the liquid load during plunger lift. This jetting of the gas causes an aeration to occur so the plunger may carry a heavy liquid load to the well top in an improved manner. In addition, a liquid load can rise at a higher velocity. The apparatus can increase the production of liquid allowing for a faster rise velocity with a fixed liquid load. 
   One aspect of the present invention is to provide a plunger apparatus that can have an extended capacity in carrying a liquid load to the well top. 
   Another aspect of the present invention is to increase lift velocity of the plunger and liquid load when rising to the well top. 
   Another aspect of the present invention is to provide a means for transferring momentum from gas at the well bottom through a gas jet and onto a liquid load to assist with overall plunger lift load. 
   Another aspect of the present invention is to provide a plunger that can be used with any existing plunger sidewall geometry. 
   Other aspects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views. 
   The present invention comprises a plunger lift apparatus having a top section with an inner longitudinal orifice and one or more nozzle exit apertures (orifices) at or near its upper surface. The top section can comprise a standard American Petroleum Institute (API) fishing neck, if desired, but other designs are possible. A mandrel mid section allowing for the various sidewall geometries comprises an internal orifice throughout its length. A lower section also comprises an internal longitudinal orifice. The sections can be assembled to form the liquid aeration plunger of the present invention. Gas passes through an internal plunger conduit (orifice), up through an internal nozzle, and out through one or more apertures thereby transferring momentum from a gas to a liquid load providing a lift assist and causing gaseous aeration of the liquid load. 
   When the surface valves open to start the lift process, down hole pressure will result in gas being forced through the plunger nozzles, exiting one or more apertures into the liquid load transferring momentum from the jetting gas onto the liquid load. The gas transfer causes aeration and results in a liquid lift assist. The plunger may carry a heavier liquid load to the well top because the aeration effectively lightens the load. The present apparatus can carry a fixed liquid load at an improved velocity as compared to a non-aerated liquid load. Applying a soapy mixture down to the well bottom between the well casing and tubing can assist the aeration process by allowing a higher surface tension in the gaseous bubbles formed within the liquid load. 
   An additional embodiment incorporates a nozzle type aerator in a bypass plunger design, employing the same basic concept of momentum transfer and gaseous aeration of the liquid load. 
   The present apparatus allows for improved productivity in wells that have large levels of loaded liquid. The disclosed plunger allows for a more efficient lift of high liquid loads both increasing the lift capacity and also the lift velocity by aerating the liquid load during plunger lift. The liquid aeration plunger is easy to manufacture, and easily incorporates into the design into existing plunger geometries. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  (prior art) is an overview depiction of a typical plunger lift system installation. 
       FIGS. 2 ,  2 A,  2 B and  2 C (prior art) are side views of plunger mandrels with various plunger sidewall geometries. 
       FIGS. 3 ,  3 A,  3 B and  3 C (prior art) are side views of fully assembled plungers each shown with a fishing neck top and utilizing various plunger sidewall geometries. 
       FIG. 4  is a cross-sectional view of an upper section embodiment of a liquid aeration plunger showing an internal orifice, nozzles, and nozzle exit apertures. 
       FIG. 5  is an isometric cut away view of a liquid aeration plunger embodiment. 
       FIG. 6  is an isometric cut away view of a liquid aeration plunger embodiment during a plunger lift. 
       FIGS. 7 ,  7 A,  7 B and  7 C (prior art) show side views of variable orifice bypass valves and plunger mandrels with various sidewall geometries. 
       FIG. 8A  (prior art) is a side cross-sectional view of a variable orifice bypass valve assembly with the actuator rod shown in the open (or bypass) position. 
       FIG. 8B  (prior art) is a side cross-sectional view of a variable orifice bypass valve assembly and similar to  FIG. 8A  but with the actuator rod shown in its closed (no bypass) position. 
       FIG. 9  is a top view of a grooved actuator rod. 
       FIGS. 9A ,  9 B show cross sectional views of possible modifications of an actuator rod for a bypass valve assembly to allow for gas entry in a closed position. 
       FIG. 9C  is a cross sectional view of  FIG. 9  along line  9 C- 9 C. 
       FIGS. 10 ,  10 A,  10 B are side cross-sectional views of the embodiments shown in  FIGS. 9C ,  9 A and  9 B respectively. 
   

   Before explaining the disclosed embodiments of the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the particular arrangement shown, since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, the present invention is a liquid aeration plunger  2000  apparatus ( FIG. 5 ) having an upper section  200  (FIGS.  4 , 5 ) with an inner longitudinal orifice and one or more nozzle exit apertures at or near its upper end. The top section can comprise a standard American Petroleum Institute (API) fishing neck, if desired, but other designs are possible. The plunger has a mandrel mid section that can accommodate various sidewall geometries, an internal orifice throughout its length and a lower section  46 A ( FIG. 5 ) with an internal longitudinal orifice. 
   All the sections can be connected together to allow the gaseous aeration of the liquid load by the plunger of the present invention. When the surface valves open to start the lift process, gas is forced through the plunger nozzles. As the gas exits from the apertures into the liquid load, transferring momentum from the gas to the liquid, a turbulent and gaseous aeration of the liquid occurs. This action results in a more efficient lift of the liquid to the well top. 
     FIG. 4  is a cross-sectional view of upper section  200  of the liquid aeration plunger shown in  FIG. 5 . The upper external end is a prior art fishing neck ‘A’ design. Upper section  200  is shown with four nozzle exit apertures  52  dispersed evenly around its upper surface, with each exiting at about 45° to the liquid load boundary. Upper section  200  can easily connect to any mandrel such as that shown in  FIGS. 2 ,  2 A,  2 B and  2 C. Internal female sleeve orifice  58  mates with the male end sleeve  41  and threaded internal female sleeve orifice  56  mates with threaded male area  42 . Upper section internal through-orifice  54  can communicate with each nozzle exit orifice  53 . It should be noted that the nozzle quantity, location, size and designs are offered by way of example and not limitation. For example, four nozzle orifices  53  and four aperture exits  52  are shown, each at about a 45° cut angle into upper section orifice  54 . However, the present invention is not limited to the design shown. Other nozzle designs could easily be incorporated to encompass one or more exit nozzle apertures, various size nozzle holes, various angles, etc. 
   The upper end has at least one exit orifice that has a total cross sectional area in the range of about 0.25% to 10% of the maximum plunger cross sectional area. Typically, the smallest range of the cross sectional area of either the lower end apertures or the upper end apertures or the internal longitudinal orifice is about 3.22 mm 2  (about 0.005 inch  2 ) to about 32.3 mm 2  (about 0.05 inch 2 ). In  FIG. 4 , the four nozzle orifices are each typically about 2.36 mm (about 0.093 inch) in diameter, combining to about 17.4 mm 2  (about 0.027 inch 2 ) of area as compared to the outside diameter of a typical plunger of about 47 mm (about 1.85 inch) or about 1735 mm 2  (about 2.69 inch 2 ). 
     FIG. 5  is an isometric cut side view of liquid aeration plunger  2000 . In this embodiment, upper section  200 , solid wall plunger mandrel  20 , and lower section  46 A, are shown having interconnected internal orifices. Lower section  46 A is modified from present art by providing lower section internal orifice  44 A. Lower section  46 A can be attached to a mandrel by mating male end sleeves  41  and threaded male areas  42 , previously shown in  FIGS. 2 ,  2 A,  2 B and  2 C. 
   Liquid aeration plunger  2000  functions to allow gas to pass into lower section  46 A at lower entry aperture  48 , up through lower section internal orifice  44 A, through internal mandrel orifice  44 , then up through upper section internal through-orifice  54 , through nozzle exit orifices  53  and finally exiting out of apertures  52 . It should also be noted that the size of nozzle exit orifices  53  and apertures  52  control the amount of gas jetting. The depicted embodiment design is shown by way of example and not limitation. It should be noted that although the mandrel shown is solid wall plunger mandrel  20 , any other sidewall geometry can be utilized including all aforementioned sidewall geometries. Lower section internal orifice  44 A, internal mandrel orifice  44 , and upper section internal through-orifice  54  can be manufactured in various internal dimensions. 
     FIG. 6  shows liquid aeration plunger  2000  during a plunger lift. When the surface valves open to start the lift process, gas G enters the plunger lower entry aperture  48 , passes up through all internal orifices ( 44 A,  44 ,  54 ,  53 ), exits apertures  52  in directions E, and jets into the liquid load L to form bubbles B in a turbulent fashion. This action results in a transfer of momentum from the jetting gas into the liquid load. The gaseous jetting, turbulence and aeration of the liquid is a result of the momentum transfer. The plunger may carry a heavier than average liquid load to the well top, thereby increasing the load capacity and/or allowing for a faster rise velocity of a given liquid load. The result is an increase in well productivity for wells with high liquid loads. 
   Injecting a soapy mixture S down to the well bottom between the aforementioned well casing  8  and tubing  9  can assist the aeration process by allowing a higher surface tension in the gaseous bubbles B formed within the liquid load L. Liquid aeration plunger  2000  can easily be manufactured with any existing plunger sidewall geometry. 
   Another embodiment of the present invention incorporates a nozzle type aerator in a bypass plunger design, employing the same basic concept of momentum transfer and gaseous aeration of the liquid load. Bypass plungers typically have an actuator that is in a ‘open’ position during plunger descent to the well bottom and is in a ‘closed’ position during a plunger rise to the well top. Modifications to the actuator rod, to the bypass valve, or mandrel housing at the closed interface can be made to accommodate an orifice or an aperture for gas jetting. In an embodiment modifying a typical bypass valve, one or more small apertures or orifices within the actuator rod provide for gas jetting into the liquid load during the ‘closed’ position of the actuator rod. Thus when in a ‘closed’ position, the bypass plunger will function via the transfer of momentum and gas jetting causing aeration of the liquid load. 
     FIGS. 7 ,  7 A,  7 B and  7 C show side views of variable orifice bypass valves (VOBV)  300 . Pad plunger mandrel section  60 A, brush plunger mandrel section  70 A, solid ring plunger mandrel section  20 A, and shifting ring plunger mandrel section  80 A can each be mounted to a VOBV  300  by mating female threaded end  64  and male threaded end  66 . Each plunger  61 ,  71 ,  21  and  81  is shown in an unassembled state. A standard American Petroleum Institute (API) internal fishing neck can also be used. Each mandrel section also has hollowed out core  67 . Each depicted bottom section is a VOBV  300  shown in its full open (or full bypass) set position. The bypass function allows fluid to flow through during the return trip to the bumper spring with the bypass closing when the plunger reaches the well bottom. The bypass feature optimizes plunger travel time in high liquid wells. The present invention is not limited by the specific design of bypass valve and VOBV is shown only as an example. 
     FIG. 8A  is a side cross-sectional view of a prior art VOBV assembly  300  with actuator rod  25  shown in the open (or bypass) position. VOBV assembly  300  threaded interface  64  joins to a mandrel section via mandrel threads  66  (See  FIGS. 7 ,  7 A,  7 B and  7 C). When VOBV assembly  300  arrives at the well top, the aforementioned striker rod within the lubricator hits actuator rod  25  at rod top end  37  moving actuator rod  25  in direction P to its open position. In its open position, the top end of actuator rod  25  rests against variable control cylinder  26  internal surface. Brake clutch  21  will hold actuator rod  25  in its open position allowing well loading (gas/fluids, etc.) to enter the open orifice and move up through the hollowed out section of bypass plunger during plunger descent. This feature optimizes its descent to the well bottom as a function of the bypass setting. Access hole  29  is for making adjustments to the bypass setting via variable orifice opening  31 . In other words, the amount of gas allowed to enter the bypass valve can be adjusted. 
     FIG. 8B  is a side cross-sectional view of a prior art VOBV assembly  300  and similar to  FIG. 8A  but with actuator rod  25  depicted in its closed (no bypass) position. When bottom bumper spring striker end  34  hits the well bottom, the actuator rod  25  moves in direction C to a closed position. In the closed position, rod top end  37  with its slant surface  36  closes against threaded top section end  66  and is held in the closed position by brake clutch  21  thus allowing VOBV  300  to be set in a closed bypass condition to enable itself to rise back to the well top. 
     FIGS. 9A ,  9 B show possible modifications of actuator rod  25  which are described in more detail below. When actuator rod  25  is in a closed position, there is a seal along slant surface  36 , which prevents gas flow through the VOBV. The modifications of the embodiment of the present invention will allow for small gas exit aperture(s) when modified actuator rods are in a closed position ( FIG. 8B ). Allowing a portion of gas to exit when in a closed position will cause the aforementioned momentum transfer from the gas into the liquid load within central hollowed out core  67  (see  FIGS. 10 ,  10 A,  10 B) and will result in a liquid lift assist in a bypass plunger. The modifications are shown by way of example and not limitation of the present invention. 
     FIGS. 9 ,  9 C are views of grooved actuator rod  25 A comprising four grooves  94  cut partially into actuator rod top surface  37 , into slant surface  36  and down top side surface  39 . The number and the type of grooves are shown by way of example and not limitation. For example, grooves also could be cut into the mating sidewall of VOBV/mandrel (not shown). In the embodiment shown, section A-A defines a cross section of grooved actuator rod  25 A. Gas would pass into the liquid residing within each mandrel section hollowed out core  67  via grooves  94 . Also shown in dotted line format is an alternate design comprising top slant holes  96  which could be drilled from top surface  37  to just below side surface  39 . Slant holes  96  could replace the aforementioned grooves  94 . Equivalent designs could include a metal burr acting to keep one rod slightly open in the closed position. 
     FIG. 9A  is a side cross-sectional view of split orifice actuator rod  25 B comprising central orifice  74 , and four connected orifices  76  positioned about 45° from each other. Gas enters at gas entry aperture  86  located at actuator rod bottom surface  34 . The gas moves up through central orifice  74 , then through nozzle orifices  76 , and exits into the liquid load from apertures  78  located along actuator rod top surface  37 . 
     FIG. 9B  is a side cross-sectional view of center orifice actuator rod  25 C comprising central through orifice  84 . Gas enters aperture  86  along actuator rod bottom surface  34  and gas exits aperture  88  at actuator rod top surface  37 . 
     FIGS. 10 ,  10 A,  10 B are side cross-sectional views of the embodiments shown in  FIGS. 9C ,  9 A and  9 B, respectively. Each design is shown by way of example and not limitation. In each case a limited amount of gas is allowed to exit the seal area of the VOBV when the actuator is in a closed position and when the down hole pressure allows gas to be jetted through the valve. 
     FIG. 10  shows VOVB assembly  300 A in a closed position. When down hole pressure is released, gas enters variable orifice opening  31  and/or access hole  29  (see FIG.  8 A) and jets through grooves  94 , transferring gas in direction GE to liquid load L. Also shown are the top slant holes  96  which could be drilled from top surface  37  to below the side surface. Slant holes  96  could replace grooves  94 . 
     FIG. 10A  is a side cross-sectional view showing split orifice actuator rod  25 B in a closed position within VOBV assembly  300 B. Split orifice actuator rod  25 B is modified to comprise central orifice  74  and four connected orifices  76  positioned about 45° from each other. Gas G enters at gas entry aperture  86  located at actuator rod bottom surface  34 . The gas moves up through central orifice  74 , through nozzle orifices  76 , and exits in direction GE into the liquid load L from apertures  78  located along actuator rod top surface  37 . 
     FIG. 10B  is a side cross-sectional view showing center orifice actuator rod  25 B in a closed position within VOBV assembly  300 C. Center orifice actuator rod  25 B comprises central through orifice  84 . Gas G enters aperture  86  along actuator rod bottom surface  34  and exits out gas exit aperture  88  in direction GE and into the liquid load L. 
   An actuator rod or side escape of the actuator rod or seal area has at least one exit orifice with a total cross sectional area in the range of about 0.25% to about 10% of the maximum plunger cross sectional area. Typically, the smallest range of the cross sectional area of the apertures (or escape area), which exit gas into hollowed out core  67 , is about 3.22 mm 2  (about 0.005 inch 2 ) to about 32.3 mm 2  (about 0.05 inch 2 ). As an example, and not a limitation, in  FIG. 10A  the four nozzle orifices are each typically about 2.36 mm (about 0.093 inch) in diameter, combining to about 17.4 mm 2  (about 0.027 inch 2 ) of area as compared to the outside diameter of a typical plunger of about 47 mm (about 1.85 inch) or about 1735 mm 2  (about 2.69 inch 2 ). 
   Examples shown above in  FIGS. 9 ,  9 A,  9 B,  10 ,  10 A and  10 B are shown by way of example and not limitation for variable type bypass valve embodiments. Modifications to fixed bypass valves, although not specifically shown, can also provide for the gas jetting in a similar manner as described above. 
   The liquid turbulence and aeration caused by the energy transfer allows for improved efficiency and productivity in wells that have high levels of liquid. The gas jetting allows for a more efficient lift of large liquid loads by increasing the plunger lift capacity of a liquid load and/or increasing the lift velocity of a given load. The liquid aeration plunger is easy to manufacture, and can easily be incorporated into the design of existing plunger geometries. As previously described, applying a soapy mixture down to the well bottom between the well casing and tubing can assist the aeration process by allowing a higher surface tension in the gaseous bubbles formed within the liquid load. 
   It should be noted that although the hardware aspects of the of the present invention have been described with reference to the depicted embodiment above, other alternate embodiments of the present invention could be easily employed by one skilled in the art to accomplish the gas momentum aspect of the present invention. For example, it will be understood that additions, deletions, and changes may be made to the orifices, apertures, or other interfaces of the plunger with respect to design other than those described herein. 
   Although the present invention has been described with reference to the depicted embodiments, numerous modifications and variations can be made and still the result will come within the scope of the invention. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.