Abstract:
A sucker rod pump with no travelling valve consisting of, from the bottom: hold down with pump inlet, lower standing valve, hollow coupling, upper standing valve suspended within the coupling, relief valve, hollow pump housing, solid piston within the housing, and barrel to clean and retain the piston in the housing. The piston attaches to and reciprocating with the rod string. Peripheral channels in the relief valve communicate between the coupling and the housing. A central channel in the relief valve communicates between the upper standing valve and the pump&#39;s outlets. The upstroke pulls fluid from the bottom of the well upward through the open lower standing valve, around the closed upper standing valve and into the housing chamber. The down stroke pushes fluid from the housing chamber past the closed lower standing valve and through the open upper standing valve to the pump&#39;s exit into the tubing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional application of U.S. patent application Ser. No. 12/391,560 for the invention entitled Double Standing Valve Sucker Rod Pump which was filed on Feb. 24, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is a sucker rod pump that employs double standing valves and does not have a traveling valve. Specifically the present pump is particularly suited for use in gas producing coal bed wells to pump off excess water from the well so that gas can be produced, although the pump is not limited to this use. 
         [0004]    2. Description of the Related Art 
         [0005]    Gas producing coal bed wells also produce water. This water must be removed from the wells so that the wells can continue to produce gas. Prior art pumps that are employed to remove this water from the wells utilize a combination of a standing valve and a traveling valve. The standing valve attaches to the tubing via a hold down device provided on the pump that engages a seating shoe on the tubing. Thus the standing valve remains stationary at the bottom of the well while in service. The traveling valve is attached to the rod string and moves in a reciprocating manner at the bottom of the well in conjunction with the up and down movement of the rod string. The water in the coal bed wells contains fine particles of coal that tend to clog the valves of these prior art pumps. 
         [0006]    The present invention addresses this problem by providing a pump that has two standing valves and no traveling valve. The two standing valves are less likely to be fouled by fine particles of coal than the prior art pumps employing a combination of a traveling valve and a standing valve. 
         [0007]    Another shortcoming of prior art sucker rod pumps is that they tend to gas lock. This is due in large part to the fact that, as the travelling valve moves upward in the well, the traveling valve moves a considerable distance away from the standing valve, creating a large fluid chamber between the two valves where gas can accumulate and cause the pump to gas lock. The present invention addresses this problem by maintaining its two standing valves in close proximity to each other and having the chamber where fluid accumulates located above both of the two standing valves. 
         [0008]    Further, prior art sucker rod pumps function by pulling or lifting the fluid from the bottom of the well in association with the upstroke of the rod string. This means that the motor that moves the rod up and down in the well must work hard to lift the weight of both the rod string and the fluid column that is being pumped to the surface. 
         [0009]    The present invention addresses this shortcoming by using the weight of the rod string to push the fluid to the top in association with the down stroke of the rod. When the rod string is lifted with the present invention, the motor that moves the rod up and down in the well only lifts the weight of the rod string, and not the weight of the fluid column that is being pumped to the surface. By using the weight of the rod string to push the fluid to the surface of the well, this creates less strain on the motor. Also because the motor is not working as hard, less energy is needed to pump the fluid to the top of the well, resulting in energy savings. 
         [0010]    The present invention is a specialized pump for the coal bed gas fields that helps pump the fluid off the well to let the gas flow. Most of these wells will produce coal dust that will pack and bind up a conventional pump. The design of this pump will keep the piston from sticking. As the piston is a solid rod and pushes the fluid to the surface, there is much less work for the unit to do since it uses the weight of the rod string to push the fluid, rather than lifting the fluid with the rod string. The motor only uses power to lift the rod string. On the upstroke, the housing fills with fluid and on the down stroke, the fluid is pushed out a bottom discharging valve, keeping the seating assembly from sanding in. The barrel of this pump has a beveled wiping edge on its upper end to keep the piston rod free from coal dust as it strokes. The barrel is short and the length of the stroke is adjusted with the length of the housing. With the shorter barrel, there is less area inside to bind. This makes it less expensive to repair. The wearing parts inside the barrel are smaller, thereby saving on the cost of spare parts. This pump will provide greater savings on downtime and repair than a common down hole pump. This cost savings will offset the slightly higher initial cost of this pump. The pump can be installed with any conventional hold down assembly. With improved materials such as carbide or ceramic valves and nickel carbide barrel, the pump will provide for long and profitable runs on wells. 
       SUMMARY OF THE INVENTION 
       [0011]    Prior art pumps that are employed to remove water from gas producing coal bed wells utilize a combination of a standing valve and a traveling valve. The standing valve attaches to the tubing via a hold down device provided on the pump that engages a seating shoe on the tubing. Thus the standing valve remains stationary at the bottom of the well while in service. The traveling valve is attached to the rod string and moves in a reciprocating manner at the bottom of the well in conjunction with the up and down movement of the rod string. 
         [0012]    During upstroke of the rod string, the standing valve of prior art pumps opens and the traveling valve closes to allow fluid to enter into the pump chamber located between the standing valve and the traveling valve. Then during down stroke of the rod string, the standing valve closes and the traveling valve opens forcing the fluid that is in the hollow rod or pump chamber to travel through the traveling valve and be force into the tubing above the seating shoe. Successive repetitions of the upstroke and down stroke of the rod string force more and more fluid into the tubing. Because the fluid can only move upward, it flows to the surface of the well within the tubing where it is removed from the well. These prior art pumps suffer from several shortcomings, including the tendency to clog up with particulate matter and to gas lock. 
         [0013]    The present invention is a double standing valve sucker rod pump that is particularly suited for use in gas producing coal bed wells to remove the water from the wells so the wells can continue to produce gas. However, this pump is not limited to this application and can be used for a variety of fluid pumping applications. This pump differs from prior art sucker rod pumps in that it does not have a traveling valve, but rather employs two standing valves to pump fluid up through the well tubing from the bottom of the well to the surface. 
         [0014]    The pump is removably secured to the bottom of the well by a hold down that is attached at the bottom of the pump that removably engages a seating shoe provided on the tubing. The seating shoe and the hold down seal the pump to the tubing and prevent fluid at the bottom of the well from flowing into the interior tubing space between the rod sting and the tubing unless it is pumped into that interior tubing space by the pump. The hold down is hollow and is provided at its lower end with an inlet for the pump. The lower end of the hold down is threaded so that an optional filter or strainer can be attached thereto to prevent large particles from entering the pump. The hold down is attached on its upper end to a lower end of a lower standing valve. 
         [0015]    An upper end of the lower standing valve is secured to a hollow coupling which houses an upper standing valve that extends downward into the hollow interior coupling chamber of the coupling. An upper end of the coupling attaches to a lower end of a relief valve. An upper end of the relief valve attaches to a lower end of the pump housing. An upper end of the housing is attached to a lower end of a pump barrel. 
         [0016]    The relief valve is provided with peripheral channels there through that allow fluid to flow from between the interior coupling chamber of the coupling and a housing chamber located within the hollow housing of the pump. The relief valve is also provided with a central channel there through that allows fluid to flow from the upper standing valve to side openings in the relief valve that serve as the outlets of the pump. 
         [0017]    A movable piston of the pump is attached at the bottom of the rod string and reciprocates up and down in the pump housing in conjunction with the up and down movement of the rod string. The piston consists of a piston rod that attaches to the rod string on its upper end and is provided with an enlarged piston cap on its lower end. The piston cap is larger in diameter than the barrel and is held within the housing by the barrel. The barrel is provided with a beveled upper opening that serves to clean the piston rod as the piston reciprocates within the barrel and housing. The reciprocating action of the piston serves to pull fluid upward into the fluid chamber within the housing on the upstroke of the piston and serves to push fluids to the surface of the well on the down stroke of the piston by forcing the fluid to pass through the upper standing valve. 
         [0018]    The lower valve consists of a lower seat, a lower ball, and a lower barrel cage that houses the lower seat and lower ball and retains the lower ball within the lower standing valve. The lower standing valve is opened when pressure below the lower ball is greater than pressure above the lower ball and, alternately, is closed when pressure above the lower ball is greater than pressure below the lower ball. During upstroke of the piston, the lower ball is open; during down stroke of the piston, the lower ball is closed. 
         [0019]    The upper standing valve attaches to a threaded lower end of the relief valve located internally within the coupling. The upper standing valve attaches to the threaded lower end of the relief valve via an upper barrel cage which houses an upper seat and upper ball that are held in place by a hollow seat plug. Similar to the lower standing valve, the upper standing valve is opened when pressure below the upper ball is greater than pressure above the upper ball and is alternately closed when pressure above the upper ball is greater than pressure below the upper ball. But opposite the positions of the lower standing valve, during upstroke of the piston, the upper ball is closed and during upstroke of the piston, the upper ball is open. 
         [0020]    The flow of fluid through the pump will now be described. During upstroke of the piston, the lower standing valve is open and the upper standing valve is closed. Thus, during upstroke of the piston, fluid flows upward into the lower end of the lower standing valve via the hollow hold down, then up through the lower seat and around the lower ball, then through the lower barrel cage before exiting the lower standing valve at its upper end and entering the hollow coupling chamber. 
         [0021]    The upper standing valve is closed so that fluid that enters the coupling chamber, flows around the outside of the upper standing valve, passes through the peripheral channels in the relief valve and enters into the housing chamber of the pump, filling the housing chamber with fluid. 
         [0022]    When the piston has finished its upward stroke, it reversed direction and begins its downward stroke. As the piston begins to move downward, the lower ball closes on the lower seat, thereby closing the lower standing valve. Simultaneously, the upper ball is lifted off of the upper seat and thereby opens the upper standing valve. As the piston continues to move downward, the fluid contained within the housing chamber flows back down through the peripheral channels in the relief valve and back into the coupling chamber. Because the lower standing valve is closed, the fluid reverses direction within the coupling chamber and flows upward into the open end of the seat plug and into the open upper standing valve. The fluid flows up through the upper seat and around the upper ball, then through the upper barrel cage before exiting the upper standing valve at its upper end and entering the central channel of the relief valve. The central channel of the relief valve is in fluid communication with side openings in the relief valve which serve as the outlets for the pump. The fluid flows out of the side openings and into the interior tubing space above the seating shoe and between the rod string and the tubing. Successive strokes of the piston force more and more fluid through the outlets and into the interior of the tubing. Because the fluid can only move upward, it flows to the surface of the well within the tubing where it is removed from the well. 
         [0023]    This pump does not have a hollow plunger rod like prior art pumps and includes a barrel attached at the top of the pump to secure the piston to the pump which is not employed in prior art pumps. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a partially cut away view of a prior art pump shown in the upstroke of the rod string with the standing valve open and the travelling valve closed. 
           [0025]      FIG. 2  is a partially cut away view of the prior art pump of  FIG. 1  shown in the down stroke of the rod string with the standing valve closed and the travelling valve open. 
           [0026]      FIG. 3  is an exploded view of a double standing valve sucker rod pump constructed in accordance with a preferred embodiment of the present invention with each piece shown in partial cut away. 
           [0027]      FIG. 4  is an enlarged perspective view of the relief valve of  FIG. 3 . 
           [0028]      FIG. 5  is a partially cut away view of the relief valve of  FIG. 4 . 
           [0029]      FIG. 6  is a cross sectional view of the relief valve taken along line  6 - 6  of  FIG. 5 . 
           [0030]      FIG. 7  is a cut away view of the double standing valve sucker rod pump of  FIG. 3  shown installed in a well and showing the flow of fluid through the pump when the piston is in down stroke mode. 
           [0031]      FIG. 8  is a cut away view of the double standing valve sucker rod pump of  FIG. 7  shown installed in a well and showing the flow of fluid through the pump when the piston is in upstroke mode. 
           [0032]      FIG. 9  is an enlarged cut away view of that portion of the pump of  FIG. 7  shown within circle  9 . 
           [0033]      FIG. 10  is an enlarged cut away view of that portion of the pump of  FIG. 8  shown within circle  10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    Referring initially to  FIGS. 1 and 2 , prior art pumps  100  that are employed to remove water  122  from gas producing coal bed wells  114  utilize a combination of a standing valve  102  and a traveling valve  104 . Hereafter water  122  will be generically referred to as fluid  122 . 
         [0035]    Although not illustrated in  FIGS. 1 and 2 , a hold down device  108  similar to the one illustrated in  FIGS. 7 and 8  threads to the bottom  101  of the standing valve  102  of the prior art pump  100 . The hold down device  108  secures the prior art pump  100  to the well tubing  106  by removably engaging a seating shoe  110  provided on the tubing  106 . Thus the standing valve  102  remains stationary at the bottom  112  of the well  114  while in service. 
         [0036]    Referring again to  FIGS. 1 and 2  in conjunction with  FIGS. 7 and 8 , the traveling valve  104  of the prior art pump  100  attaches to the rod string  116  and moves in a reciprocating manner at the bottom  112  of the well  114  in conjunction with the up and down movement of the rod string  116 . 
         [0037]    Referring specifically to  FIG. 1 , during upstroke of the rod string  116 , as indicated by the arrow U, the standing valve  102  of prior art pumps  100  opens and the traveling valve  104  closes to allow fluid  122  to enter into a pump chamber  118  located between the standing valve  102  and the traveling valve  104 . 
         [0038]    Now referring to  FIG. 2 , during down stroke of the rod string  116 , as indicated by Arrow D, the standing valve  102  closes and the traveling valve  104  opens, thereby forcing the fluid  122  that is in the pump chamber  118  to travel through the traveling valve  104  and be forced into a fluid chamber  124  of the pump  100  that is located above the traveling valve  104 . Although not illustrated, this fluid chamber  124  opens to the interior tubing space  120 . The interior tubing space  120  is external to and surrounds the pump  100  and the rod string  116  and is located internally or within the tubing  106  and extends from the seating shoe  110  upward to the surface of the well  114 . 
         [0039]    When the next upstroke of the rod string  116  occurs, the fluid  122  that is now located within the fluid chamber  124  must be raised along with the rod string  116  and the traveling valve  104  in order to pump the fluid to the surface. During the upstroke, the rod string  116  has the weight of the fluid  122  that is located within the fluid chamber  124  and the weight of the entire fluid column located within the interior tubing space  120  pushing downward on the rod string  116 . Thus, the rod string  116  has a huge weight that it has to lift on each upstroke. 
         [0040]    Successive repetitions of the upstroke and down stroke of the rod string  116  force more and more fluid  122  into the interior tubing space  120  of tubing  106 . Because the fluid  122  can only move upward, it flows to the surface of the well  114  within the tubing  106  where it is removed from the well  114 . In addition to the energy and strain on the equipment required to pump the fluid  122  to the surface with these prior art pumps  100 , they also suffer from several other shortcomings, including the tendency to clog up with particulate matter and to gas lock. 
         [0041]    Referring now to  FIGS. 3 ,  7  and  8 , there is illustrated a double standing valve sucker rod pump  10  constructed in accordance with a preferred embodiment of the present invention. The pump  10  is particularly suited for use in gas producing coal bed wells  114  to remove the water  122  from the wells  114  so the wells  114  can continue to produce gas. However, this pump  10  is not limited to this application and can be used for a variety of fluid pumping applications. This pump  10  differs from prior art sucker rod pumps  100  in that it does not have a traveling valve  104 , but rather employs two standing valves  12 L and  12 U to pump fluid  122  up through the interior tubing space  120  of the well tubing  106  from the bottom  112  of the well  114  to the surface. 
         [0042]    As illustrated in  FIGS. 7 and 8 , the pump  10  is removably secured to the bottom  112  of the well  114  by a hold down  108  attached at the bottom of the pump  10  that removably engages a seating shoe  110  provided on the tubing  106 . Jointly, the seating shoe  110  and the hold down  108  seal the pump  10  to the tubing  106  and prevent fluid  122  at the bottom  112  of the well  114  from flowing into the interior tubing space  120  located above the seating shoe  110  and between the rod sting  116  and the tubing  106  unless it is pumped into that interior tubing space  120  by the pump  10 . 
         [0043]    Referring now also to  FIG. 3 , the hold down  108  is hollow and is provided at its lower end  14  with an inlet  16  for the pump  10 . The lower end  14  of the hold down  108  is threaded so that an optional filter or strainer  18  can be attached thereto to prevent large particles from entering the pump  10 . The hold down  108  is attached on its upper end  20  to a lower end  22  of a lower standing valve  12 L. A typical hold down  108  is illustrated in  FIG. 3  and shown as several individual pieces that are held together by threads. Those pieces typically are a body  128 , seals  130 , spacers  132 , a seal retaining ring  134  and a seating nipple  136 . 
         [0044]    An upper end  24  of the lower standing valve  12 L is secured to a lower end  25  of a hollow coupling  26 . The hollow coupling  26  houses the upper standing valve  12 U that extends downward into a hollow interior coupling chamber  28  located with the coupling  26 . An upper end  30  of the coupling  26  attaches to a lower end  32  of a relief valve  34 . An upper end  36  of the relief valve  34  attaches to a lower end  38  of the pump housing  40 . An upper end  42  of the housing  40  is attached to a lower end  44  of a pump barrel  46 . An upper end  48  of the pump barrel  46  is freestanding within the well  114 , supported by the hold down  108 . 
         [0045]    Referring to  FIGS. 4 ,  5 , and  6 , the relief valve  34  is provided with a plurality of peripheral channels  50  that extend longitudinal through the relief valve  34 . The peripheral channels  50  allow fluid  122  to flow freely back and forth between the interior coupling chamber  28  of the coupling  26  located below the relief valve  34  and a housing chamber  52  provided within the hollow housing  40  of the pump  10  which is located above the relief valve  34 . 
         [0046]    The relief valve  34  is also provided with a central channel  54  that extends from the lower end  32  of relief valve  34  longitudinally upward partially through the relief valve  34 . The central channel  54  is in fluid communication with two side openings  56  provided in the relief valve  34  so that fluid  122  that flows from the upper standing valve  12 U and through the central channel  54  exits the pump via the relief valve&#39;s side openings  56 . The side openings  56  are in fluid communication with the interior tubing space  120  and serve as outlets  56  of the pump  10 . 
         [0047]    A movable piston  60  of the pump  10  is attached at the bottom of the rod string  116  and reciprocates up and down in the pump housing  40  in conjunction with the up and down movement of the rod string  116 . The piston  60  consists of a piston rod  62  that attaches to the rod string  116  via an upper end  64  of the piston rod  62  and an enlarged piston cap  66  attached to a lower end  68  of the piston rod  62 . The piston cap  66  is larger in diameter than the barrel  46  so that the piston cap  66  is held within the housing chamber  52  by the barrel  46 . The barrel  46  is provided with a beveled upper opening  70  within which the piston rod  62  reciprocates. The beveled upper opening  70  serves to clean the piston rod  62  as the piston  60  reciprocates within the barrel  46  and housing  40 . Because of the tight clearance between the piston cap  66  and the housing  40 , the reciprocating action of the piston  60  within the housing chamber  52  serves to pull fluid  122  upward into the housing chamber  52  on the upstroke of the piston  60 . Also, the reciprocating action of the piston  60  serves to push fluid  122  to the surface of the well  114  on the down stroke of the piston  60  by forcing the fluid  122  to pass through the upper standing valve  12 U. The pump  10  uses the downward stroke and the weight of the rod string  116  to push the fluid  122  to the surface of the well  114  instead of lifting the fluid  122  in the manner of prior art pumps  100 . 
         [0048]    Referring now to  FIG. 3 , the lower standing valve  12 L consists of a lower seat  72 , a lower ball  74 , and a lower barrel cage  76  that houses the lower seat  72  and lower ball  74  and retains the lower ball  74  within the lower standing valve  12 L. The lower standing valve  12 L is opened when pressure below the lower ball  74  is greater than pressure above the lower ball  74 . Alternately, the lower standing valve  12 L is closed when pressure above the lower ball  74  is greater than pressure below the lower ball  74 . During upstroke of the piston  60 , the lower ball  74  is open. During down stroke of the piston  60 , the lower ball  74  is closed. 
         [0049]    Continuing to refer to  FIG. 3 , an upper end  77  of the upper standing valve  12 U attaches to a centrally located threaded lower end  78  of the relief valve  34  located internally within the coupling  26 . The upper standing valve  12 U attaches to the centrally located threaded lower end  78  of the relief valve  34  via an upper barrel cage  80  which houses an upper seat  82  and upper ball  84  that are held in place by a hollow seat plug  86 . Similar to the lower standing valve  12 L, the upper standing valve  12 U is opened when pressure below the upper ball  84  is greater than pressure above the upper ball  84  and is alternately closed when pressure above the upper ball  84  is greater than pressure below the upper ball  84 . During upstroke of the piston  60 , the upper ball  84  is closed and during upstroke of the piston  60 , the upper ball  60  is open. Thus, when the lower standing valve  12 L is open, the upper standing valve  12 U is closed. Likewise, when the lower standing valve  12 L is closed, the upper standing valve  12 U is open. 
         [0050]    The flow of fluid  122  through the pump  10  will now be described in reference to  FIGS. 7-10 .  FIGS. 7 and 9  show flow of fluid  122  associated with upstroke of the piston  60  and  FIGS. 8 and 10  show flow associated with down stroke of the piston  60 . The smaller arrows appearing in  FIGS. 7 and 8  and all of the arrows appearing in  FIGS. 9 and 10  indicate the flow path of the of fluid  122  through and in association with the pump  10 . 
         [0051]    During upstroke of the piston  60 , as indicated by Arrow U in  FIG. 7 , the lower standing valve  12 L is open and the upper standing valve  12 U is closed. Thus, during upstroke of the piston  60 , fluid  122  flows upward into the lower end  22  of the lower standing valve  12 L via the hollow hold down  108 , then up through the lower seat  72  and around the lower ball  74 , then through the lower barrel cage  76  before exiting the lower standing valve  12 L at its upper end  24  and entering the hollow coupling chamber  28 . 
         [0052]    The upper standing valve  12 U is closed so that fluid  122  that enters the coupling chamber  28  flows around the outside of the upper standing valve  12 U and passes through the peripheral channels  50  in the relief valve  34  and enters into the housing chamber  52  of the pump  10 , filling the housing chamber  52  with fluid  122 . 
         [0053]    When the piston  60  has finished its upward stroke, it reverses direction and begins its downward stroke. As the piston  60  begins to move downward, as indicated by Arrow D in  FIG. 7  the lower ball  74  closes on the lower seat  72 , thereby closing the lower standing valve  12 L. Simultaneously, the upper ball  84  is lifted off of the upper seat  82  and thereby opens the upper standing valve  12 U. As the piston  60  continues to move downward, the fluid  122  contained within the housing chamber  52  flows back down through the peripheral channels  50  in the relief valve  34  and back into the coupling chamber  28 . Because the lower standing valve  12 L is closed, the fluid  122  reverses direction within the coupling chamber  28  and flows upward into the open end of the seat plug  86  and into the open upper standing valve  12 U. The fluid  122  flows up through the upper seat  82  and around the upper ball  84 , then through the upper barrel cage  80  before exiting the upper end  77  of the upper standing valve  12 U and entering the central channel  54  of the relief valve  34 . The central channel  54  of the relief valve  34  is in fluid communication with side openings  56  in the relief valve  34  which serve as the outlets  56  for the pump  10 . The fluid  122  flows out of the side openings  56  and into the interior tubing space  120  located above the seating shoe  110  and between the rod string  116  and the tubing  106 . Successive strokes of the piston  60  force more and more fluid  122  through the outlets  56  and into the interior of the tubing  106 . Because the fluid  122  can only move upward, it flows to the surface of the well  114  within the tubing  106  where it is removed from the well  114 . 
         [0054]    While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for the purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.