Abstract:
A float valve with upper and lower valve bodies having axial flow there through and valve member having angular trailing edges at a swept back angle for providing a seating surface and a stem axially extending from the valve member. The stem having multiple supporting surfaces arranged cylindrically and having a biasing member fitted there about. The upper valve body having an internal annular seat for seating with the valve member seating surface and external seals for engaging oilfield tubulars and threaded on one end. The lower valve body having a central internal support member for support of the valve member stem for axial movement and threaded on one end for joining the upper valve body and compressing the biasing member to engage the seating surfaces of the valve member and internal annular seat of the upper valve body for engagement and disengagement in response to fluid flow pressure.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of application Ser. No. 12/454,819 filed on May 29, 2009, titled “Down-Hole Float Valve and Joint Strainer Assembly”. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an improved float valve of the type used in hydrocarbon recovery operations with oilfield tubular materials in downhole operations. More particularly this invention relates to a float valve which can be used in either vertical or horizontal well bores and provides smooth functionality in the transition between vertical or horizontal well bores and improved life of the float valve. The invention further relates to the ease of the float valve assembly for all its parts and for precise and exact tolerance relationships for all its parts when assembled. The invention provides improved fluid flow through the float valve and sealing relationship by providing functionally improved angles between its seating surfaces. Also this invention provides improved fluid flow through the float valve by improved configurations of the axial stem of the valve member movably mounted in the float valve. This invention also provides surfaces and landing sites on the float valve for technology associated with sub joint strainers, spiders or X-collar filters to be used in cooperation with the float valve for improved performance. 
         [0004]    2. Background of the Invention 
         [0005]    Float valves have long been used in oilfield drilling operations with drilling fluids for drilling oil and gas wells. However over time, improvements have been made to drilling operations which include lateral wells, as well as vertical wells, and ever more exotic drilling fluids, gels and even high pressure air had been put into use. The new drilling fluids pass through the drill string like the older drilling fluids, and through the float valve but create new and enhanced stress and wear on the float valves, especially in lateral wells. In the case of high pressure air drilling operations for example, a float valve may open and close in excess of a hundred times per minute thereby exerting excessive forces on the moving valve member parts. Also new components have been developed for drilling fluid such as glass or other kinds of beads which are very fine, but abrasive, and can stick between moving parts of a float valve. Further lateral wells put the float valve and drilling head into a different gravitational alignment than vertical drilling which can cause wear and alignment problems with moving parts of a float valve. 
         [0006]    The float valve is generally installed in a tubular string for running in a well bore by installing the float valve in a float body or bored-out drill collar of a tubular string. The float body may be positioned between two joints in a tubular string and is conventionally connected to the tubular string with conventional oilfield tubular threads such as a threaded box and pin connections for sealing engagement with conventional oil field tubular threads. When the float valve is positioned within the float body, seals provided on the exterior of the float valve body engage against the interior surfaces of the float body and provide a seal against high and low pressure fluids passing between the float body and the exterior of the float valve. Once the seal between float body and the exterior of the float valve is sealed all fluids are then flowed through the float valve and controlled by the float valve. 
         [0007]    Fluid flow through a float valve body is controlled by the pressure of the fluid being flowed against a valve member positioned within the float valve body which overcomes the valve member&#39;s sealed and seated relationship against the seat on the interior surface of the float valve body which is created by the biased engagement of a spring against the valve member. While a float valve is necessary to control backflow from within the well and allow down flow of fluids being flowed from above, a float valve also is a restriction to flow in the profile between the valve member seat and the angular seat in the interior of the float valve body even when the float valve is fully open. This restrictive flow profile can have an affect on the functionality of the drilling operation and can create wear on those parts exposed to flow. Also the flow profile opening, between the valve member seat and the angular seat of the float body, can create turbulence in the fluid passing through which can cause vibration in the moving parts of the float valve. Further vibration and turbulence in the presence of drilling fluids, which contain drilling muds, chemicals, drill cuttings, glass or other kinds of beads, etc. can have abrasive affects on the valve member at the edges of its seating surfaces and on the stem of the valve member and on the spring for creating excessive wear which leads to a short life and ultimate failure of the float valve. Also the drilling fluids can, because of their small particle size, become jammed between the moving surfaces of the valve member stem and its supporting structure within the float valve body to create problems. Also this turbulence interferes with the smooth fluid flow of the drilling fluid to the drill bit or other piece of equipment in the drill string and therefore it is desirable to have a smooth flow and as large a volume of flow as possible through a float valve. 
         [0008]    The prior art float valves have included a unitary valve member which was cast in one piece and included both the stem and valve member head, which engaged the valve seat located in the interior of the float valve body. Due to the exotic surfaces necessary to form a seal and the high cost of manufacturing this unitary valve element, two-piece valve elements are more commonly used in float valves and joined together at their stem and valve member head by conventional means. Various means of joining the two-piece, stem and valve member head, have been used including inertia welding and other mechanical interconnectors. Even exotic special means of connection were used such as using a shrink fit operation where the valve member head/cone includes a cylindrical shaped recess for receiving a front end of the stem during the shrink fit operation, wherein the valve member head/cone is heated relative to the stem, and the stem is impressed into the cylindrical recess for union and then both are air cooled for connection. This fitting or union is subject to being damaged in drilling operations because of the elevated downhole temperatures and due to vibrations to which the valve stem and valve member head/cone are subjected, specially in lateral well forces. 
         [0009]    The float valve bodies, into which the valve members are inserted, are today cast as a single piece unit which creates problems with assembly. Assembling such cast valves bodies requires a window in the casting to allow for the insertion and manipulation of the valve member head with its valve stem and spring into the float valve body through the window. To achieve this large clearances must be allowed for such awkward installation which often results in wobble or deviation of the valve member head and its stem within the float valve body, thereby resulting in excessive wear on the valve member head and its stem and the valve stem bearing/bushing which shorten the life of the float valve. The wobbles and deviations of the valve member head and it&#39;s stem within a float valve bodies cast as a single piece are even greater and more likely to cause failure in an horizontal wells because of gravitational forces being perpendicular to the stem and valve member head. 
         [0010]    The prior art float valves have also tended to use elastomeric seals and valve bushings with valve member heads to affect sealing engagement and allow smooth movement of the stem within the float valve between its open and closed positions. The prior art float valves using elastomeric seals tended to use large angles for the valve member head seats which were 45° to 90° and greater, because the valve head seats were not the primary source of sealing engagement but were used in conjunction with the elastomeric seal to form the seal between valve member head and the seat of the float valve body. This arrangement formed a good seal, but as the elastomeric seals wore down from operation in the abrasive environment of drilling fluids, these prior art float valves had a shorter life and were subject to catastrophic failure. The other soft spot for failure in the prior art float valves was at the valve bushing into which the stem of the valve member head was mounted to provide a smooth surface on which to slide back and forth in the operation of opening and closing the float valve. In the current drilling fluid environment these valve bushings/bearing were rapidly destroyed by the drilling fluids and thus left the stem of the valve member head loose in its mounting which allowed wobble in the valve member head and caused early failure of the float valve. This problem is especially acute in lateral wells because of the gravitational force being perpendicular to the stem of the valve head member versus being in alignment with the gravitational forces in vertical wells. 
         [0011]    The prior art tended to focus on creating a reliable float valve, but did not focus as much on the flow profile of the opening between the valve head member and its seat on the inside of the float valve body and the flow passage through the rest of the float valve body where the stem of the valve head member and supporting structure were located to create smooth non-turbulent flow through the float valve. Thus the prior art provided seating surfaces on the valve head member which were 45° to 90° or greater angles through the line of the flow and thus seating surface on the interior of the valve body tended to be a problem. These angles for the seating surfaces tended to push the drilling fluid out of its normal path of flow and create excess turbulence at that point of flow in the valve body. In addition, the prior art did not provide for any cover or protection of the spring member and stem to the corrosive and abrasive fluid turbulence created by the seating surfaces on the valve head member just behind the valve member head where the spring and stem were located thereby exposing them to excessive wear which caused early failure in float valves. Also the prior art stems were generally cylindrical rods mounted in a sleeve bearing/bushing which was mounted in a supporting structure within the flow way of the lower half of the valve body to support the stem for smooth and even movement in and out as the float valve was operated. The cylindrical rods and support structure for them with sleeve bearings/bushing took up a great deal of cross-sectional area in the float valve body and restricted flow and positioned the sleeve bearing/bushing directly in line with corrosive and abrasive turbulent flow of the drilling fluid causing early failure in the float valve. These failures occurred in many ways, but in at least one way, as the drilling fluids destroyed the sleeve bearing/bushing it began to open up crevices which allowed the drilling fluids and their small particles to be jammed in between the stem and sleeve bearing/bushing not only causing additional wear but in some instances prevented the stem from sliding in and out in the sleeve bearing/bushing causing failure of the float valve. 
         [0012]    Those skilled in the art would recognize that failure of a float valve can have significant adverse consequences, because any failed piece of equipment in a drill string requires a trip out and back in to the well which interferes with drilling operations. The prior art float valves were treated as separate units apart from sub joint strainers or X-collar filters which were used apart from the float valves to stop foreign particles in the drilling fluid from being jammed into the float valves or other operational equipment below and could not and did not function in direct relationship with a float valve or could be landed and be seated on a float valve because the float valve were not built to receive such filters and strainers. 
       OBJECTS OF THE INVENTION 
       [0013]    It is the object of this invention to provide an improved float valve for use in drilling operations which can be used in vertical or horizontal well bores and function smoothly in the transition from vertical or horizontal in the well bore as the gravitational forces shift from alignment with the float valve to being perpendicular to the float valve while being joined to the drill string in a conventional way. Also it is an object of this invention to provide a float valve which can work with and endure exotic drilling fluids gels and high pressure air and additive such as glass or other kinds of beads and still have an improved life for the float valve, while providing improved fluid follow and reduced turbulence in the flow through the float valve. 
         [0014]    It is an object of this invention to utilize typical float valve elements such as a valve body, valve member which has a the valve member head and a stem which extends axially from the valve member head, a biasing member positioned about the stem and support structures for the stem for allowing the valve member head to move back and forth to form alternatively sealing and opening in response to fluid flow, but to use novel parts and configurations to achieve a novel result and an improved float valve while eliminating the soft parts such as elastomeric seals and sleeve bearings/bushings, which are prone to wear rapidly in the drilling fluid environment. 
         [0015]    The valve body of the float valve of this invention is comprised of an upper tubular valve body member and a lower tubular valve body member, rather than a single cast valve body with a window in the valve body for insertion of the valve member and includes a valve member head with an axial stem, and a resilient/spring member. This upper and lower tubular valve body member of this invention are joined together by threads to create a unitized valve body with very tight tolerances. The upper valve body member has axial flow there through and has an internal angular seat for seating with the seating surface of the valve member and an external seal for sealing engagement with oilfield tubulars and threads on the lower part of the upper tubular valve body member. The lower tubular valve body member has axial flow there through and has an internal web portion with a central longitudinal support member which has an axial aperture therein for providing surfaces for support and for allowing axial movement of the stem of the valve member and the valve member when the stem is inserted in the axial aperture. Once the stem is inserted in the axial aperture of the lower tubular valve body member the upper tubular valve body member may be joined by threading the upper and lower tubular valve body members together. In the process of joining the upper and lower tubular valve body members they compress the spring biasing member positioned about the stem to engage the seating surfaces of the beveled trailing edge of the head portion of the valve member with an internal annular beveled seat of the upper tubular body member to make the float valve operational. Thus it can be seen that this invention allows for easy installation of the valve member in the valve body and creates a float valve with exacting tolerances between its parts to prevent misalignment and vibration of the moving parts. 
         [0016]    Also an object of this invention is to provide a float valve which is easy to assemble and which does not require a window in the body of the float valve for insertion or manipulation of the valve member head, stem, and spring biasing member through the window into the float valve body. It is the object of this invention that as all float valve parts are assembled they have precise and exact tolerances in relationships with each other to work together smoothly for enhanced float valve life. This is achieved in this invention by using a valve body member which is composed of an upper and lower tubular valve body members which are joined by threads to form the float valve body and a valve member having an axial stem and a spring located about the stem for biasing the valve member into engagement within the valve body of the float valve. The upper tubular valve body member has an upper and lower part which allows axial flow there through and has an internal angular beveled seat for seating with the valve member seat and external seals for sealing engagement with the oilfield tubular or valve body which is joined to the tubular string of a well. The upper tubular valve body member has threads for being joined to the lower tubular valve body member. The lower tubular valve body member also has upper and lower parts for axial flow there through but lower tubular valve body member has an internal web portion which has a central longitudinal support member provided with an axial aperture therein for providing surfaces for support and allowing axial movement of the valve member with the axial stem in the valve body member. The precision and simplicity of assembly can be understood by the fact that stem of the valve member is inserted into the axial aperture of the internal web portion in the lower tubular valve body member with the spring about the stem and then the upper tubular valve body member is threadly connected to the lower valve body member. As this connection progresses to completion the valve member and spring are compressed to engage the valve member into engagement with the internal annular beveled seating surface of the upper tubular valve body member for creating an operational float valve with precise tolerances and relationships. The tolerances and structural relationships are such that there is no need for elastomeric seals or valve bearings/bushings as will become evident from further objects and descriptions to follow. 
         [0017]    As a part of this invention, it is an object to provide enhanced fluid flow and long-lasting seal relationship of the valve surfaces by providing functionally improved angles between the seating surfaces which provide for smooth fluid flow through the float valve and over its valve seating surfaces. Also as part of this improved fluid flow is an improved configuration of the axial stem of the valve member in the float valve which is movably mounted in the float valve. The improved fluid flow and long-lasting sealing relationship of the valve seating surfaces are provided by the head member of the valve member seating surfaces having an angular trailing edge portion at a swept back angle of 45° or less than 45° from the axial alignment with the stem of the valve member. The internal and angular beveled seat of the upper tubular valve body member is formed at a complementary angle to the valve member seating surface to form substantially matching seating surfaces with the valve member seating surfaces when the two are engaged. The swept back angles of 45° or less than 45° provide less obstruction to the fluid flow and also provides a self centering valve seat for the valve member. One of the enhanced benefits of having swept back angles of 45° or less than 45° from the axial alignment with the stem of the valve member is the forming of a relatively large surface area for the seat of the float valve of this invention which is less subject to wear and can thus be used with the improved drilling techniques and fluids and also used in lateral wells as well as vertical wells. Thus the float valve of this invention can be used with high pressure air drilling operations or with the new gels and muds containing glass or other kinds of beads without any effect on its moving parts or from abrasion from the muds in both lateral and vertical wells. 
         [0018]    The float valve of this invention uses a unitary valve member, which includes both a stem and a valve member head, which some cases is a conical head, having angular trailing edge portions beveled off at the trailing edge portion of the valve member head which creates a swept back angle from the head portion for providing a seating surface. By using a unitized valve member, the float valve of this invention eliminates the failure between the valve member head and stem which commonly occurs in two-piece valve elements which are commonly used. Also the use of the unitary valve member having angular trailing edge portions beveled off at the trailing edge portion to create a swept back angle for providing a seating surface provides a self centering seating surface of the valve member for complete alignment of the valve member in the float valve and transmits the forces smoothly throughout the valve member body eliminating vibration. Because the valve member is a unitary piece there are no joints between the valve member head and the stem to be broken apart during the transmission of forces through the valve member. 
         [0019]    As part of the improved fluid flow through the float valve is an enhanced configuration of the axial stem of the valve member in the float valve which is movably mounted in the float valve. This enhancement provides a stem portion from the valve head member as a unitary piece having at least three contact surfaces for engagement with the surfaces forming the axial aperture of the central and longitudinal support member for allowing axial movement and for support of the stem portion of the valve member. The, at least three contact surfaces, triangular shape stem removes much cross-section area of the stem relative to the fluid flow and allows more fluid flow. It also eliminates the need for sleeve bearings and bushings to be used about the stem which also improves the fluid flow and extends the life of the float valve by eliminating these short lived parts. 
         [0020]    Another object of this invention is to provide a protective cover on the valve member to cover the spring biasing member as the valve member is moved axially to a fully open position in the lower valve body member in response to fluid flow. This protects the spring biasing member from the drilling fluids which are circling and swirling about in the axial flow through the valve body member. Thus this protective cover on the valve member extends the life of the spring biasing member and therefore extends the life of the float valve. 
         [0021]    While this float valve operates like other float valves to control backflow from within the well and allow down flow fluids to flow downward, the float valve of this invention is less disruptive of the flow in the profiles section between the valve member seat and the angular seat in the interior of the float valve body whether the float valve is partially opened or is fully open. This reduction of disruptive flow is because the seating surfaces of the valve member of this float valve are swept back at angles of 45° or less than 45° from the axial alignment with the stem of the valve member thus not protruding out into the fluid flow stream and allow the flow to stream by with little disruption. Also less turbulence is less restriction to fluid flow in passing the drilling fluid which produces less wear on the stem of the valve member and the spring which extends the life the float valve of this invention. 
         [0022]    Yet another enhancement of this float valve is the elimination of elastomeric seals and valve bushings or bearings and yet it still provides sealing engagement and smooth movement of the stem within the float valve from its open and close positions. 
         [0023]    The float valve of this invention may be installed in a conventional manner in a float body or bored out drill collar of a tubular string and is sealed against exterior fluid flow between the float valve body and the float body directing all fluids through the float valve. The float valve of this invention however has surfaces on the float valve body which are provided for receiving and positioning sub joint strainers or X-collar filters above the point of the drilling fluid entrance into the float valve, for filtering out debris before it passes into the float valve and further down the well bore to other operational drilling equipment which could be damaged if allowed to pass through. Thus sub joint strainers or X-collar filters may be landed on the float valve body and used in conjunction with the float valve for improved performance and contribute to smooth fluid flow into the float valve body and to prevent debris from passing into the float valve body causing it to fail. 
         [0024]    These and further objects, features, advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the coming drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    Some of the objects and advantages of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0026]      FIG. 1  is a side view, partially in cross-section, of one embodiment of the float valve of this invention in a closed position positioned in a float body in a drill string of a well and having an X-filter landed on its surfaces designed for receiving same. 
           [0027]      FIG. 2  is a side view, partially in cross-section, of one embodiment of the float valve of this invention in a closed position. 
           [0028]      FIG. 3  is a side view of the float valve of this invention with the upper tubular valve body member and lower tubular valve body member joined together and showing grooved surfaces for seals and at least one notch receiving member formed in the upper part of the upper tubular valve body. 
           [0029]      FIG. 4  is a bottom view of the float valve of this invention showing the lower tubular valve body member with its internal web portion and longitudinal support member with axial aperture and a stem of the valve member inserted therein. 
           [0030]      FIG. 5  is a top view of the float valve this invention with X-filter landed in place. 
           [0031]      FIG. 6  is an exploded view of one embodiment of the float valve of this invention showing the landing surface for receiving the joint strainer and X-collar filter. 
           [0032]      FIG. 7  is a side view, partially in cross-section, of the float valve this invention with the upper tubular valve body member and lower tubular valve body member joined together showing the valve member in an open position and a cover member protecting the biasing member from fluid flow. 
           [0033]      FIG. 8  is a perspective view of one embodiment of the valve member of this invention showing the stem portion of the valve member having a conical head portion and a stem with three contact surfaces for engagement in the axial aperture of the central and longitudinal support members of the lower tubular valve body member and cover member for protecting the biasing member. 
           [0034]      FIG. 9  is a side view of one embodiment of the valve member of this invention showing the valve member with the angular trailing edge portion beveled off at a swept back β- 1  angle from the head portion of the valve member for providing a seating surface and showing a stem portion axially extending from the head portion of the valve member and showing the cover member mounted to protect the biasing member and showing a complementary β- 2  angle. 
           [0035]      FIG. 10  is a bottom view of one embodiment of the float valve of this invention showing the lower tubular valve body member with its internal web portion and longitudinal support member with axial aperture and stem with three contact surfaces engaging the surfaces created by the axial aperture. 
           [0036]      FIG. 11  is a cross-sectional side view of one embodiment of the float valve of this invention in a well bore showing the progression of the float valve from a vertical position to a lateral position in the well bore with the gravitational force lines shown. 
           [0037]      FIG. 12  is a cross-sectional side view of one embodiment of the float valve of this invention in well bore in a lateral position in the well with the gravitational force lines shown. 
           [0038]      FIG. 13  is a partial cross-section view of one embodiment of the float valve of this invention in an open position and showing flow through the float valve. 
           [0039]      FIG. 14  is a representational cross-sectional view of one embodiment of the bottom view of the lower tubular valve body member of the stem portion of the valve member from  FIG. 13  showing at least three contact members for engaging the surfaces created by the axial aperture of the central and longitudinal sport members in the lower tubular body member and showing the range of surface contact of the stem portion by the bisected arc of angles α 1  to α 2  from the center of the stem portion to the surface of the stem portion. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0040]    Referring to  FIG. 1  wherein at least one embodiment of the float valve of this invention is shown as it might be positioned in a drill string of an oil field tubular string positioned downhole in a well bore, it can be seen the float valve  10  is installed or inserted in a float body  11 . The float body  11  is connected to the tubular string  12  between two joints in the tubular string  12  by conventional oilfield tubular threads such as threaded box  13  and pin connections  14  for sealing engagement with conventional oilfield tubular threads  15 . The float valve  10  is composed of two parts an upper tubular valve body member  16  and a lower tubular valve body member  17  which are open to axial flow there through and when joined together form a generally cylindrical exterior surface for insertion in float body  11 . The upper tubular valve body member  16  is provided with angular grooves  18  for receiving external seals  19  which when put in place form a seal between the float valve  10  and the float body  11  to prevent fluid flow between the float valve  10  and the float body  11 , such that all flow will be directed axially through the float valve  10 . Float body  11  maybe be provided as shown with a stopping surface  20  to finally position the float valve  10  within the float body  11 . As those skilled in the art will recognize the above description for mounting the float valve  10  is a very general description and that there are many and various configurations which could be used to position the float valve  10  in the tubular string  12  without departing from the scope of this invention. 
         [0041]    The float valve  10  in  FIGS. 2 and 3  is generally composed of an upper tubular valve body member  16  and a lower tubular valve body member  17  which may be joined together to form the float valve  10  having a valve member  21  and biasing member  22  positioned within the upper tubular valve body member  16  and lower tubular valve body member  17 . The biasing member  22  is positioned about the valve member  21  for biasing the valve member  21  into a closed position within the float valve  10  when upper tubular valve body member  16  and a lower tubular valve body member  17  are joined. 
         [0042]    The valve member  21 , in this embodiment, is composed of a conical head portion  23  and an angular trailing edge portion at a swept back angle from the conical head portion  23  for providing a seating surface  24  and has a stem portion  25  which axially extends from the head portion  23  of the valve member  21 . The biasing member  22  is positioned about the stem portion  25  of the valve member  21  for biasing the valve member  21  into a closed position within the float valve  10 . 
         [0043]    The upper tubular valve body member  16  of the float valve  10  has upper and lower parts  26  and  27  with an axial flow path  28  there through and has an internal annular beveled seat  29  for seating with the seating surface  24  of the valve member  21 . The upper tubular valve body member  16  also has external grooved surfaces  18  for receiving external seals  19  for sealing engagement with the float body  11  connected to the oilfield tubular string  12  to form a seal between the float body  11  and the float valve  10  and thus prevents fluid flow from passing either uphold or downhole between the upper tubular valve body member  16  and float body  11  in the drill string  12  in the well bore. The upper tubular valve body member  16  also has threads  38  on the lower part  27  of the upper tubular body  16  for being joined with the lower valve body member  17 . 
         [0044]    The lower valve body member  17  has an upper and lower part  32  and  33  with an axial flow path  34  there through and has an internal web portion  35 , as can be seen in  FIGS. 2 ,  4  and  10 , with a central longitudinal support member  36  which has an axial aperture  37  therein for providing surfaces for support and allowing axial movement of stem portion  25  of the valve member  21  when the stem portion  25  is inserted in the axial aperture  37 . The lower tubular valve body member  17  also has threads  39  on the upper part  32  of the lower tubular valve body  17  for being joined with the upper valve body member  16  to form the float valve  10 . 
         [0045]    The internal web portion  35  as seen in  FIGS. 2 ,  4 , and  10  is connected to the lower valve body member  17  across the axial flow path  34  to locate the central longitudinal support member  36  in a central axial location such that the axial aperture  37  therein will be positioned to receive the stem portion  25  of the valve member  21  when stem portion  25  is inserted in the axial aperture  37  for central axial positioning of the stem portion  25  of the valve member  21  which positions the valve member  21  in a central axial position in the float valve  10  of this invention. 
         [0046]      FIG. 6  shows the assembly of the float valve  10  of this invention such that the parts are in precise and exact tolerances with each other and work smoothly together for enhanced float valve life. Referring to  FIG. 6  where the valve member  21  with its stem portion  25  is inserted in the axial aperture  37  of the central and longitudinal support member  36  of lower valve body member  17  with the biasing member  22  positioned about the stem portion  25 , one can see once assembled then the upper tubular valve body member  16  with its threads  38  are engaged with the lower valve body member  17  with its threads  39  for driving the seating surfaces  24  of the valve member  21  downward for compressing the biasing member  22  to engage the seating surfaces  24  of the head portion  23  of valve member  21  against the internal annular beveled seat  29  of the upper tubular valve body member  16 . This process of assembly therefore creates a self seating relationship between seating surfaces  24  of the head portion  23  with the internal annular beveled seat  29  when the float valve  10  of this invention is assembled and allows for tolerances between the stem portion  25  of the valve member  21  and axial aperture  37  in the central longitudinal support member  36  for the elimination of elastomeric seals, valve bearings, and bushings from the float valve  10  of this invention. 
         [0047]    To Further understand how the self seating relationship of the sealing surfaces and improved seating surfaces of the float valve  10  of this invention operate, reference may be made to  FIGS. 2 ,  7 , and  9 , where one skilled in the art must first understand the function of the improved angles between its seating surfaces which provide for smooth fluid flow through the float valve and over the seating surfaces. As can be seen in  FIGS. 2 ,  7 , and  9  the surfaces between the seating surface  24  of the head portion  23  of valve member  21  are formed at angles β- 1  from an angle from a line with the axial alignment with the stem portion  25  of valve member  21  and the internal angular beveled seat  29  of upper tubular valve body member  16  are formed at complementary angles β- 2  from an angle from a line with the axial alignment with the stem portion  25  of valve member  21  to form complementary angles with the total of the angles β- 1  and β- 2  equaling 180° and creating substantially matching seating surfaces of substantially the same surface area for forming a seal when these surfaces are engaged. For example, if β- 1  angle was a 20° angle for seating surface  24  of the head portion  23  of valve member  21 , then β- 2  angle would be 160° so that the sum angle total would be 180°, as shown in the  FIG. 9 . Therefore, the seating surfaces have a substantially large surface area because they represent diagonal lines through relatively thick materials and are not subject to being worn down rapidly as other prior art smaller seating surfaces. Also because the angles formed are less than 45°, and in a preferred embodiment angles β- 1 , as shown in  FIG. 9 , range from 10° to 35°, from a line in axial alignment with stem portion  25  of the valve member  21 , the seating surface  24  of the head portion  23  of valve member  21  do not project very much into the axial flow path  34  and provide improved fluid flow and long-lasting seating surfaces. Also because those seating surfaces  24 , as shown in  FIGS. 7 ,  9 , and  13 , are at the angular trailing edge portion of the head portion  23  and are at a swept back angle out of the line of flow seating surface  24  of the head portion  23  of the valve member  21  presents a more fluid dynamic profile to the direction of flow through the float valve  10  which reduces turbulence in the float valve  10  of this invention. Because of this reduction in turbulence the float valve  10  of this invention can be used with improved drilling techniques and fluids with new gels and mud containing glass or other kinds of beads and even used with high pressure air drilling operations without any affect on the moving parts from vibration or abrasion both in lateral and vertical wells. 
         [0048]    Also the valve member  21  of this invention is composed of a unitized piece of material as can be seen in  FIG. 9  which includes both stem portion  25  and head portion  23  which may be conical head as shown or flat head as not shown, as opposed to being composed of two pieces joined together, therefore the valve member  21  is less likely to have a failure between the head portion  23  and the stem portion  25  in response to transmission of cocking forces through the valve member  21 . Also by the valve member  21  having angular trailing edge portion beveled off at the trailing edge portion it creates a swept back angle from the head portion  23  for providing a seating surface  24  which makes valve member  21  a self centering seating valve member  21  with internal angular beveled seat  29  and it provides for better alignment of the valve member  21  and minimizes force moments between the stem portion  25  and the head portion  23  of valve member  21  and as a unitized piece is better at distributing cocking or sticking or force moments which may occur. 
         [0049]    These cocking or sticking moments are especially pronounced in lateral wells as the valve member  21 , as shown in  FIGS. 11 and 12 , is perpendicular to the force of gravity  31  which provides an opportunity for the head portion  23  of the valve member  21  to catch or drag and create a cocking or sticking moment within the float valve  10 . The value of valve member  21  has a self centering seating effect by having angular trailing edge portion beveled off at the trailing edge portion to create a swept back angle for the head portion  23  can be seen in  FIGS. 11 and 12  which allows it to be pushed into aligned seating even when the gravitational forces are in axial alignment with the valve member  21  in  FIG. 11  when the float valve  10  is in the vertical part of the well and/or when the gravitational forces  31  are perpendicular to the axial alignment of the valve member  21  when the float valve  10  is in the horizontal part of the well. As  FIG. 11  shows, a well bore  49  which begins as vertical well bore  49 V and transitions to a horizontal well bore  49 H with the float valve  10  located there in dramatizes the full range of gravitational forces  31  float valve  10  experience in moving from vertical in a well to horizontal in a well. Referring now to  FIG. 12  the float valve from  FIG. 11  is shown with the gravitational forces  31  acting perpendicular to the axial alignment the valve member  21  and it can easily be seen how the seating surface  24  of the head portion  25  of valve member  21  would be inclined to move smoothly along the interior surfaces of the lower tubular valve body member  17  as the valve member  21  is moved from seating engagement with internal angular beveled seat  29  of upper tubular valve body member  16  to valve member  21  being moved to a fully open position. Also by seating surface  24  of the head portion  23  of valve member  21  having angular trailing edge portion beveled off at a swept back angle from the head portion  23  one skilled in the art can see the seating surface  24  would be inclined to move smoothly along the interior surface of lower valve body member  17  until it reaches the internal angular beveled seat  29  of the upper tubular valve body member  16  and then into self centering seating with internal angular beveled seat  29  without cocking or sticking moments. 
         [0050]    Also, as part of the improvement to the float valve  10  of this invention, in at least some embodiments, as shown in  FIGS. 8 ,  9 ,  10 , and  14 , the stem portion  25  of valve member  21  in addition to being made of a unitized piece, it may also be provided as having at least three contact surfaces in the form of a triangular shaped stem  40  for insertion into the axial aperture  37  of the central longitudinal support member  36  in lower tubular valve body member  17 . By referring to  FIG. 10 , those skilled in the art will appreciate that a triangular shaped stem  40  removes much of the cross-sectional area of a rod like stem portion  25 , as in  FIG. 1 , relative to fluid flow and allows more fluid flow through the axial flow path  34  and it also reduces the amount of surface contact between the triangular shaped stem  40  and the axial aperture  37  which allows elimination of sleeve bearings and bushings used about the stem which ultimately extend the life of the float valve by eliminating these relatively short-lived parts from the float valve  10 . With reduced surface area contact between the axial aperture  37  and triangular shaped stem  40  there is also less chance for cocking moments to provide misalignment or sticking between the surfaces. Also, the reduced amount of surface area which allows more fluid flow through the axial flow path  34  provides for a smoother flow and more flow and eliminates turbulence in the flow path  34 . As can be seen in  FIG. 14  the amount of surface area contact between the triangular shaped stem  40  and the axial aperture  37  can be computed or defined by a bisected arc of angles α 1  to α 2  which range from 5° to 35° from the center of the triangular stem portion  40  to the surface of the triangular stem portion  40  for determination of how much material is in contact between a triangular stem portion  40  and axial aperture  37 . As those skilled in the art will appreciate the contact surfaces of the triangular stem portion  40  of float valve  21  may have more contact surfaces than three and possibly up to eight contact surfaces, not shown, without departing from the scope of this invention. 
         [0051]    Also in some embodiments of this invention, as shown in  FIGS. 2 ,  7 ,  8 , and  9 , a cover member  41  is attached to the head portion  23  of valve member  21  and is positioned concentrically about stem portion  25  and extends axially from the head portion  23  sufficiently to allow biasing member  22  to be received between the cover member  41  and the stem portion  25  for protecting the biasing member  22  as the valve  21  is moved axially in the float valve  10  in response to fluid flow as shown in  FIG. 7 . 
         [0052]    The central longitudinal support member  36  in the lower tubular valve body member  17  which has the axial aperture  37  there in for providing support and allowing axial slidable movement for the stem portion  25  or triangle stem portion  40  also provides a guide stabilizer portion  42  for acting as a stop  30  for the biasing member  22  and for receiving the biasing member  22  there about as the stem portion  25  or triangle stem portion  40  of the valve member  21  is moved axially in the lower tubular valve body member  17  in response to fluid flow. Also provided is a guiding angular leading edge  43  on the guide stabilizer portion  42  for guiding the biasing member  22  about the guide stabilizer portion  42  for providing alignment of the biasing member  22  as the valve member  21  is moved axially in response to flow as shown in  FIGS. 7 and 13 . The guide stabilizer portion  42  with the guiding angular leading edge  43  as shown in  FIGS. 1 and 5  is also guiding the biasing member  22  into position over the guide stabilizer portion  42  for preventing wear to the biasing member  22  as it is repeatedly axially moved in and out over the guide stabilizer portion  42  in response to fluid flow through the float valve  10 . It will be appreciated by those skilled in the art from the above description that for the cover member  41  and guide stabilizer portion  42  to work in cooperation to cover and receive the biasing member  22  against fluid flow through the float valve  10  that the cover member  41  and the guide stabilizer portion  42  must have lengths sufficient to cover and receive the biasing member  22  when the triangle stem portion  40  is moved axially to a fully open position in the lower tubular valve body member  17  in response to fluid flow when the triangle stem portion  40  of valve member  21  moved axially to fully open position in response to fluid flow for allowing full coverage of the biasing member  22  by the cover member  41  and full support by the guide stabilizer portion  42  without interference of either the cover member  41  or the guide stabilizer portion  42  by the other. 
         [0053]    Also by referring to  FIGS. 1 ,  2 ,  7  and  13 , the guide stabilizer portion  42  can be seen to be a tubular extension of the central longitudinal support member  36  which extends the support structure into which the axial aperture  37  is formed for providing support for allowing axial slidable movement of the stem portion  25  or triangle stem portion  40  of the valve member  21  through the axial aperture  37  formed by both the guide stabilizer portion  42  and central longitudinal support member  36 . The axial aperture  37  formed by both the guide stabilizer portion  42  and the central longitudinal support member  36  for support of the stem portion  25  or triangle stem portion  40  of the valve number  21  to allow axial slidable movement has been found to be most effective for slidable engagement without being cocked or jamming the stem portion  25  or triangle stem portion  40  of valve member  21  in its movement when the support surface of the axial aperture  37  formed in the central longitudinal support member  36  and the guide stabilizer portion  42  have a combined support surface which supports 30 to 60% of the stem portion  25  or triangle stem portion  40  of the valve member  21 . It will be appreciated by those skilled in the art, that if a float valve  10  is being used only in a vertical well bore that the percentage of support can be moved toward the lower range of 30% support and if the float valve  10  is being used in a well with both lateral and vertical well bore configuration, that percentage of support would be moved toward the higher range 60% of support for the stem portion  25  or triangle stem portion  40  of the valve member  21 . 
         [0054]    While X-collar filters for filtering fluid flow and various leg spiders for filtering flow and performing other functions in the well bore may be known to those skilled in the art, they would not be aware of or find obvious float valves which were designed or provided with angular seating members for receiving X-collar filters and notched seating members for receiving the legs of various spiders, because the prior art float valves were deprived of the capability of working with X-collar filters and spiders. Referring to  FIGS. 1 ,  2 ,  5 ,  6 ,  7 , and  13  it can be seen that the float valve of this invention provides and includes the novel concept of providing angular seat member  44  and notched seating members  45  for respectively receiving X-collar filters  46  and spiders  47  with legs  48  configuration for being landed on float valve  10  of this invention. This novel combination of providing angular seat members  44  and notched seating surfaces  45  on the upper tubular valve body member  16  at its upper part  26  provides a valuable and novel combination which can be used to prevent damage to the float valve  10  and other drilling equipment below the float valve  10  by combining anger seat member  44  and notched seating surfaces  45  on the float valve  10  with the landed X-collar filters  46  and spiders  47  for filtering fluids before entry into the float valve  10 . 
         [0055]    It will be understood by those skilled in the art that there will be various modifications to the float valve  10  of this invention apart from the above description of the preferred embodiments. While preferred embodiments of this invention have been described in detail, it should be understood that this explanation is for illustration only and that the invention is not limited to the disclosed embodiments. It should be understood that alternative float valves for use in vertical and lateral wells and alternative valve elements for use in the float valves will be apparent to those skilled in the art in view of this disclosure, it does not minimize scope of this invention. Modifications to the described structure and operation of this float valve are thus contemplated and may be made without departing from the spirit of the invention which is defined by the claims. 
         [0056]    In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.