Patent Publication Number: US-6659741-B2

Title: Travelling valve assembly for a fluid pump

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/236,482 filed Sep. 29, 2000 entitled Travelling Valve Assembly for a Fluid Pump. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a travelling valve assembly for a fluid pump for elevating fluids, and in particular, to a travelling valve assembly for a fluid pump for raising petroleum fluids through production tubing in completed oil wells. 
     2. Description of Related Art 
     A conventional oil well includes a cased well bore with one or more strings of tubing extending downwardly through the casing into the oil or other petroleum fluid contained in the sub-surface mineral formation to be produced. The casing is perforated at the level of the production zone to permit fluid flow from the formation into the casing, and the lower end of the tubing string is generally open to provide entry for the fluid into the tubing. 
     One type of pump conventionally employed in structures of the type described is wedged into an internal constriction or seating nipple formed internally of the tubing below the fluid level. A metallic enlargement on the external body of the pump prevents it from travelling below the seating nipple and resilient seal rings on the body of the pump housing, or pump barrel, act to form a leak proof seal between the seating nipple and pump housing, or barrel. The pump is generally driven by a mechanical linkage of metal rods, generally referred to as sucker rods, or valve rods, which extend from the pump to the well surface. The valve rod, or sucker rod, linkage is powered in a reciprocating motion by a conventional mechanical apparatus, usually called a pumping unit located at the well surface. 
     The conventional pump itself generally includes a housing through which a piston is reciprocated by the sucker rod, or valve road, linkage. In its simplest form, the conventional pump of the type described often includes a number of ball and seat valves with one such valve in, above, or below, the piston, or a travelling valve assembly, and another at the inlet port of the housing or barrel. On the upstroke of the plunger, the ball in the inlet port valve is drawn away from its seat and the ball of the outlet port valve is forced over its seat to draw fluid from below the seating nipple and into the housing. On the piston&#39;s downstroke, the ball in the inlet valve is forced onto its seat and the ball in the piston valve, or travelling valve, moves away from its seat to allow the piston to move downwardly through the fluid contained in the housing. On the subsequent upstroke, the closing of the piston valve forces the fluid above the piston out of the housing through the outlet ports and into the tubing above the sealing nipple and simultaneously fills the housing below the piston with fluid. Repetition of this cycle eventually fills the tubing string and causes the fluid to flow to the surface. 
     The previously described pump or some variation thereof is probably the most widely employed in applications where it is desired to drive a sub-surface pump by a surface powered, mechanical linkage. A significant problem in pumps of this type is that the ball of the travelling valve assembly, during the downstroke typically rotates within its housing, or cage, in the same general path, and the ball wears out the cage, whereby the pump must be pulled from the well, so that the cage may be replaced. 
     Accordingly, prior to the development of the present invention, there has been no travelling valve assembly for a sucker rod actuated fluid pump for raising petroleum fluids through production tubing in completed oil wells which prevents excessive wear to the cage, or housing, of the travelling valve assembly, which can lead to failure of the pump. Therefore, the art has sought a travelling valve assembly for a sucker rod actuated fluid pump for raising petroleum fluids through production tubing in completed oil wells which reduces excessive wear to the cage, or housing, of the travelling valve assembly, thus increasing the time within which the fluid pump may be used before pulling the pump to replace travelling valve assembly components, such as the cage, or housing. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the foregoing advantages have been achieved through the present travelling valve assembly, for use in a sucker rod actuated fluid pump which has a pump barrel and a moveable piston, or plunger, disposed within the pump barrel. 
     The travelling valve assembly of the present invention, when compared with previously proposed prior art travelling valve assemblies for fluid pumps, has the advantage of preventing excessive wear to the cage, or housing, of the travelling valve assembly; and additionally is believed to provide: the pumping of more fluid per pump stroke; reduced operating costs for the well; and increased fluid production. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a partial cross-sectional view along the longitudinal axis of a fluid pump and travelling valve assembly in accordance with the present invention; 
     FIG. 2 is a partial cross-sectional view along the longitudinal axis of the travelling valve assembly of FIG. 1; 
     FIG. 3 is a partial cross-sectional view along the longitudinal axis of the travelling valve assembly of FIGS. 1 and 2, with the ball illustrated in a downstroke position; 
     FIG. 4 is a partial cross-sectional view of a portion of the travelling valve assembly of FIGS. 1-3; and 
     FIG. 5 is an end view taken along line  5 — 5  of FIG.  4 . 
    
    
     While the invention will be described in connection with the preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, a fluid pump  60  for elevating fluids, in particular a fluid pump  60  for raising petroleum fluids (not shown) through production tubing (not shown) in a completed oil well is shown to include a conventional pump barrel, or housing,  61 , having upper and lower ends  62 ,  63 , with a conventional standing valve  65  disposed at the lower end  63  of pump barrel  61 . Standing valve  65  is typically a conventional ball check valve and seat  66 , 67 . Fluid pump  60  includes at least one conventional sucker rod, or valve rod,  68  and a moveable piston, or plunger,  69  is disposed within the pump barrel  61  in a sliding, sealing relationship with the interior surface  70  of barrel  61 . As is known in the art, fluid pump  60  may also include a conventional hold down assembly  71  at the lower end  63  of the pump barrel  61 ; and a valve rod bushing  72 , valve rod guide  73 , connector member  74 , and barrel connector member  75  disposed above pump barrel  61 . If desired, a conventional, optional top valve housing  76  may be interposed between connector member  74  and barrel connector member  75 . 
     Still with reference to FIG. 1, a travelling valve assembly  80 , in accordance with the present invention, is disposed at the lower end  77  of plunger  69 . With reference to FIGS. 1-3, travelling valve assembly  80  is shown to generally comprise: a housing  81  having upper and lower ends  82 ,  83 ; a flow through body member  84 , generally disposed within the upper end  82  of housing  81 , and which is adapted to be secured to the lower end  77  of plunger  69 ; a ball, or ball valve,  85 ; a conventional seat member  86 , generally disposed toward and within the lower end  83  of housing  81 ; and a seat plug member  87  (FIG. 1) received within the lower end  83  of housing  81 , which retain valve seat  86  within housing  81 . FIG. 2 illustrates the location of ball  85  in its seated position upon seat  86  during the upstroke of fluid pump  60 . FIG. 3 illustrates a location of ball  85  within housing  81  of travelling valve assembly  80  during the downstroke of the fluid pump  60 . 
     As is conventional in the art, when ball  85  is in an open, fluid transmitting position such as is illustrated in FIG. 3 with respect to the valve seat  86 , the configuration of travelling valve assembly  80  corresponds to a point in time when sucker rod, or valve rod  68  is travelling through its downstroke movement. During the downstroke movement of valve rod, or sucker rod,  68 , the lower standing valve  65  is closed as illustrated in FIG. 1, due to the compression of the fluid (not shown) contained in the lower end  63  of pump barrel  61  by the downward movement of piston, or plunger,  69 . Because ball valve, or ball,  85  is disposed in its first open, fluid transmitting position, as shown in FIG. 3 with respect to seat, or valve seat,  86 , the fluid being compressed by plunger  69  can flow upwardly past ball valve  85 , out of housing  81 , and through pump barrel  61  into the production tubing string (not shown). 
     With reference to FIG. 2, travelling valve assembly  80  is illustrated in its configuration while sucker rod, or valve rod,  68  is moving upwardly during its upstroke movement. During the upstroke of valve rod  68 , ball, or ball valve  85  is shown in its second sealed, fluid non-transmitting position with respect to valve seat  86 . During the upstroke of sucker rod  68 , plunger  69  would also be moving upwardly and the vacuum created by such upward movement within barrel  61  causes lower standing valve  65  to open (not shown) to allow fluid to flow into the lower end  63  of barrel  61 , as is conventional in the art. 
     With reference to FIGS. 2-5, travelling valve assembly  80  will be described in further detail. The upper end  90  of flow through body member  84  is preferably threaded, such as by internal threads  91 , which permit flow through body member  84  to be threaded upon the lower end  77  of plunger  69 . Alternatively, if desired, the threads  91  could be located on the exterior of the upper end  90  of flow through body member  84  which threads would be threadedly received within the lower end  77  of plunger  69 . An intermediate portion  92  of flow through body member  84  may be provided with exterior threads  93  which are threadedly received within the upper end  82  of housing  81 . Alternatively, if desired the flow through body member  84  could be formed integrally with housing  81 . Flow through body member  84  includes a central passageway  95 , having an upper end  96  and a lower end  97 . At the lower end  97  of central passageway  95 , flow through body member  84  is preferably provided with at least one, and preferably three, flutes, or rounded grooves,  100  which have downwardly disposed spider members  101  disposed between adjacent flutes  100 . The flutes  100  are in fluid communication with central passageway  95 , and permit the flow of fluids therethrough with the fluid being capable of passing from the lower end  83  of housing  81  through flutes  100  into central passageway  95 , and then out of the upper end  90  of flow through body member  84 . 
     In the preferred embodiment, three flutes, or rounded grooves,  100 , are utilized; however, it will be readily understood that a greater, or fewer, number of flutes may be provided. The flutes  100  provide three fluid passageways  102  which are thus in fluid communication with central passageway  95  of flow through body member  84 . The flutes  100  and their corresponding fluid passageways  102  may be formed, as by first drilling, grinding, or milling into flow through body member  84  along the axes  103  (FIG. 5) in the direction of arrows  104  (FIG.  4 ). Then another drilling, grinding, or milling operation, may be performed along axis,  105 , one such axis being illustrated in FIG. 4, in a direction along arrows  106  in FIG. 5, and arrow  107  (FIG.  4 ). The lower ends  110  of spider members  101  form a ball impact surface  115 , which preferably is a substantially flat planar surface disposed substantially perpendicular to the longitudinal axis  116  of flow through body member  84 . Longitudinal axis  116  is also coincident with the longitudinal axis of housing  81 . If desired ball impact surface  115  could be slightly concave, or slightly convex, with respect to the longitudinal axis  116  of flow through body member  84 , provided it does not provide any sharp projections which could potentially damage ball valve  85 , upon ball valve  85  impacting upon ball impact surface  115 . 
     Still with reference to FIGS. 2-5, the lower end  120  of flow through body member  84  is preferably provided with a downwardly depending member  121 , which preferably includes at least one, and preferably only one, flute, or rounded groove,  122 . Preferably, the various end surfaces  125  of downwardly depending member  121  have a rounded configuration, so as to not damage ball  85 , upon ball  85  contacting downwardly depending member  121 , as will hereinafter described in greater detail. Preferably, as shown in FIGS. 2-5, downwardly depending member  121  and spider members  101  are all formed as an integral part of flow through body member  84 . 
     With reference to FIGS. 2 and 3, the operation of travelling valve assembly  80  will be described. During the upstroke of fluid pump  60  with ball valve  85  in its seated, sealing relationship with seat  86 , as previously described, travelling valve assembly  80  functions in a conventional manner. Upon the beginning of the downstroke of fluid pump  60 , wherein ball valve  85  rises off of seat  86  into a fluid transmitting relationship, it is believed that ball  85  moves upwardly within housing  81 , until it is forced into an abutting relationship with the ball impact surface  115  of flow through body member  84 . It is possible that ball  85  might first also contact a portion, or surface, of downwardly depending member  121 , as well. As fluid passes into housing  81  through seat  86 , ball  85  will begin to rotate within housing  81  in a plane which is generally perpendicular to the longitudinal axis  116  of flow through body member  84 . In conventional travelling valve assemblies, the rotation of the ball within its cage, or housing, generally takes place in the same plane disposed substantially perpendicular to the longitudinal axis of the cage, or housing, of the conventional travelling valve assembly. In contrast, with the travelling valve assembly  80  of the present invention, upon the ball  85  beginning to rotate within housing  81  in a plane generally perpendicular to the longitudinal axis  116  of flow through body member  84 , ball  85  will strike downwardly depending member  121 . It is believed that the ball  85  striking downwardly depending member  121  tends to slow down the movement of ball  85 , as well as direct ball  85  into a different plane with respect to the longitudinal axis  116  of flow through body member  84 . Upon ball  85  then rotating again until it contacts downwardly depending member  121 , ball  85  is again slowed down and is believed to be again deflected into another different, and random orientation and location within housing  81 , thus not subjecting housing  81  to the excessive wear, and ultimate failure, encountered by conventional housings or cages of conventional travelling valve assemblies. 
     It should be apparent one of ordinary skill in the art that all of the components of the foregoing described fluid pump  60  may be made of any suitable metallic material having the requisite strength and durability characteristics to function in the manner previously described. Preferably travelling valve assembly  80  is made of Nitronic 50 austenitic stainless steel, XM-19 austenitic stainless steel, or K-500 monel stainless steel. 
     It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiment shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. For example, the shape of the downwardly depending member could be varied from that shown in the drawing. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.