A disclosure is provided describing a filling and circulating tool and method of use. The filling and circulating tool comprises a tubular housing having a first fluid passage and a longitudinal axis, a movable seal coupled to an exterior of the housing, the seal adapted to substantially block a flow of fluid through the first fluid passage when the seal is in a closed position and to allow the flow of fluid when the seal is in an open position, and an actuating device coupled to the movable seal such that in response to insertion into the casing, the actuating device causes the movable seal to move from the closed position to the open position.

FIELD OF THE INVENTION  
       [0001]     This invention relates to filling a portion of casing while it is being run in a wellbore and circulating it to aid in its proper positioning as it is being advanced into the wellbore.  
       BACKGROUND OF THE INVENTION  
       [0002]     Casing for a wellbore that has just been drilled is assembled at the surface as joints are added and the string is lowered into the wellbore. As the joints are added at the surface on the rig floor, it is often desirable to fill the casing with fluid or drilling mud. Filling the casing before it is run into the wellbore prevents pressure imbalances on the casing as it is being advanced into the wellbore. Additionally, once the casing is filled, it may be desirable to circulate through the casing as it is being run into the wellbore. Thus, it is often necessary to use an apparatus for filling and circulating fluids within the casing. When such an apparatus is raised from the casing, fluids may leak onto the well deck, which wastes valuable fluids, may be hazardous to personnel, and could cause environmental issues. Furthermore, such an apparatus may build up excessive back pressure causing potentially dangerous situations. What is needed, therefore, is an apparatus and method which safely allows for the adequate filling and circulating of the casing.  
       SUMMARY  
       [0003]     The present invention relates to a filling and circulating tool and a method of use thereof. The filling and circulating tool comprises a housing having a first fluid passage and a longitudinal axis, a movable seal coupled to an exterior of the housing, the seal adapted to substantially block a flow of fluid through the first fluid passage when the seal is in a closed position and to allow the flow of fluid when the seal is in an open position, and an actuating device coupled to the movable seal such that in response to insertion into the casing, the actuating device causes the movable seal to move from the closed position to the open position. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a longitudinal cross section of one embodiment of the present invention.  
         [0005]      FIG. 2  is an elevation of the embodiment of  FIG. 1  illustrating the embodiment in a closed position.  
         [0006]      FIG. 3   a  is a detailed cross section of one embodiment of a valve apparatus which could be employed in the embodiment of the present invention.  
         [0007]      FIG. 3   b  is a detailed cross section of an alternative embodiment of a valve apparatus which could be employed in the embodiment of the present invention.  
         [0008]      FIG. 4  is an elevation of the embodiment of  FIG. 1  illustrating the embodiment in an open position. 
     
    
     DESCRIPTION  
       [0009]     Referring now to  FIG. 1 , there is shown an embodiment of a filling and circulating tool  10 . As will be explained below with reference to the operation of the filling and circulating tool  10 ,  FIG. 1  illustrates a first or “closed” configuration. The filling and circulating tool  10  has an outer housing  12  which is generally cylindrical in shape and encloses the various modules and components of one embodiment of the present invention. At the upper end of the outer housing  12 , there is an upper connecting sub  14  which is adapted to be connected to the bottom of a tool string (not shown) in a conventional manner.  
         [0010]     A top opening  16  is concentrically located in the upper connecting sub  14 . The top opening  16  defines an end of a first fluid passageway or central throughbore  18  which generally runs through the filling and circulating tool  10  along a vertical or longitudinal axis  20 . In one embodiment, the upper connecting sub  14  has a threaded inside surface  22  adapted to connect to the tool string (not shown). The lower end of the upper connecting sub  14  may be connected to a tubular shaped mandrel  24  in a conventional manner, for instance, by means of a threaded connection  25 . The interior of the mandrel  24  defines a portion of the central throughbore  18 . A sealing means, such as a plurality of O-rings (not shown) may provide a sealing engagement between the upper connecting sub  14  and the mandrel  24 .  
         [0011]     In the illustrative embodiment of  FIG. 1 , the lower end of the mandrel  24  connects to a valve body  26  in a conventional manner, such as a threaded connection  28 . A sealing means, such as a plurality of O-rings (not shown) may provide a sealing engagement between the mandrel  24  and the valve body  26 . As will be explained in detail below, the valve body  26  contains a plurality of fluid ports  30  which are in communication with the central throughbore  18 . In the configuration illustrated in  FIG. 1 , a valve sleeve  32  is slidably coupled to the valve body such that the valve sleeve  32  may move longitudinally with respect to the valve body  26  from a “first” or closed position to a “second” or open position. As will be explained in detail below, in the closed position, the valve sleeve  32  covers the fluid ports  30  to prevent fluid from exiting. On the other hand, in the open position, the valve sleeve  32  does not cover the fluid ports  30 , allowing fluids to escape. The valve sleeve may have a means of protection, such as a urethane standoff ring  31 , to protect against casing and thread damage. Additionally, the standoff ring  31  may act as a guide to assist in centralizing the tool  10  within the casing.  
         [0012]     An actuating device  38  may be coupled to the valve sleeve  32 . The actuating device  38  causes the valve sleeve  32  to move from the closed position to the open position. A lower end of the valve body  26  may be adapted to be coupled to a nose guide  34  which also contains a plurality of fluid passages  36 . The nose guide  34  protects the filling and circulating tool  10  and aids in the insertion of the tool into the casing. The nose guide  34  can also protect the casing threads.  
         [0013]     Turning now to  FIG. 2 , there is an exterior view of the filling and circulating tool  10 . In the illustrated embodiment, the actuating device  38  is coupled to the exterior of the mandrel  24 . The actuating device  38  may comprise an anchor collar  50 , a collar or scissor sleeve  52 , and a plurality of scissor arms  54   a  and  54   b . The anchor collar  50  may be fixedly coupled to the mandrel  24 . In alternative embodiments, the anchor collar  50  may function as a connecting sub which connects an upper mandrel  56  to a lower mandrel  58 . The plurality of scissor arms  54   a  and  54   b  connects the anchor collar  50  to the scissor sleeve  52  and allows the scissor sleeve  52  to slidingly move longitudinally along the mandrel  24  with respect to the anchor collar  50 . Lower segments  55   a  and  55   b  of the the scissor arms  54   a  and  54   b  may have a means of protection, such as urethane thread protectors  57   a  and  57   b  to shield the segments  55   a  and  55   b  when entering a casing.  
         [0014]     The scissor sleeve  52  may be coupled to a plurality of connecting rods  60   a  and  60   b  ( 60   a  is visible in  FIG. 2 ). In one embodiment, the ends of the connecting rods may be threaded. In such an embodiment, a lower end  59   a  of the connecting rod  60   b  may be threadably coupled to the valve sleeve  32 . An upper end  59   b  of the connecting rod  60   b  may be positioned within a longitudinal bore (not shown) defined within the scissor sleeve  52 . A plurality of locking nuts (not shown) positioned above and below the bore may be used to secure the upper end  59   b  of the connecting rod  60   b  to the scissor sleeve  52 . Thus, as illustrated, the connecting rods  60   a  and  60   b  couple the scissor sleeve  52  to the valve sleeve  32  so that when the scissor sleeve  52  moves longitudinally, the valve sleeve  32  will follow with the same relative movement. In some embodiments, a center portion  59   c  of the connecting rods  60   a  and  60   b  may be positioned within and slidingly engage a longitudinal bore (not shown) defined within the anchor collar  50 .  
         [0015]      FIG. 3   a  is a detailed view of one embodiment of the valve body  26 . As previously discussed, the upper end of the valve body  26  may be adapted to connect to the lower end of the mandrel  24  in a conventional manner, such as with the threaded connection  28 . A top opening  64  is concentrically located in the valve body  26 . The top opening  64  defines a concentric bore  66  which is a portion of the central throughbore  18 . In the illustrative embodiment, the fluid ports  30   a - 30   d  run through the side walls of the valve body  26  (fluid ports  30   a ,  30   b , and  30   c  are visible in  FIG. 3   a ). A sealing mechanism, such as a plurality of 0-rings  68   a  and  68   b  or U-cup seals (not shown) such as those commercially available from MARCO Rubber Plastic Products, Inc. of North Andover, Mass., provide a seal when the valve sleeve  32  (not shown in  FIG. 3   a ) covers the ports  30 .  
         [0016]     At approximately the middle of the valve body  26 , the concentric bore  66  narrows down to a neck  70  and then expands again to create a fluid passage  72 . The fluid passage  72  may contain a valve mechanism, such as a nylon ball  74  positioned within the fluid passage  72 . A biasing mechanism, such as a helical spring  75 , may bias the ball  74  against the neck  70 . In the illustrative embodiment, the force exerted by the helical spring  75  against the ball  74  may be adjusted by means of a threaded mechanism  77  positioned within the fluid passage  72 .  
         [0017]     The bottom portion  76  of the valve body  26  may be coupled to the nose guide  34  by means of a threaded connection  78 . The nose guide  34  may be urethane, plastic, brass or another suitable material to protect the valve body  26  and casing threads during use. As will be explained below, the nose guide  34  may have a plurality of fluid passages  36   a  and  36   b  which may allow fluid to escape during times of high back pressure.  
         [0018]      FIG. 3   b  is a detailed view of an alternative embodiment of a valve body  80 . As illustrated, the valve body  80  is similar to the valve body  26  discussed in reference to  FIG. 3   a . The upper end of the valve body  80  may be adapted to connect to the lower end of the mandrel  24  in a conventional manner, such as with the threaded connection  28 . A top opening  82  is concentrically located within the valve body  80 . The top opening  82  defines a concentric bore  84  which may be a portion of the central throughbore  18 . In the illustrative embodiment, the fluid ports  86   a - 86   d  run through the side walls of the valve body  80  (fluid ports  86   a ,  86   b , and  86   c  are visible in  FIG. 3   b ). A sealing mechanism, such as a plurality of U Cup seals  88   a  and  88   b , provide a seal when the valve sleeve  32  covers the ports  86   a - 86   d  (as illustrated in  FIG. 3   b ).  
         [0019]     At approximately the middle of the valve body  80 , the concentric bore  84  widens to form an a downward facing radial flange  90  coupled to a plunger seat  92 . The widened portion of the concentric bore  84  forms a fluid passage  94 . The fluid passage  94  may contain a valve mechanism, such as a plunger  96  positioned within the fluid passage  94 . A biasing mechanism, such as a helical spring  98 , may bias the plunger  96  against the plunger seat  92 . In the illustrative embodiment, the force exerted by the helical spring  98  against the plunger seat  92  may be adjusted by means of a threaded mechanism, such as a compression nut  100 , positioned within the fluid passage  94 . In some embodiments, a spacer sleeve  102  may be coupled to the compression nut  100  to longitudinally position the compression nut  100  within the fluid passage  94 .  
         [0020]     A bottom portion  104  of the valve body  80  may be coupled to a guide nose  106 . The guide nose  106  may be urethane, plastic, brass or another suitable material to protect the valve body  80  during use. The guide nose  106  may have a plurality of fluid passages  108   a  and  108   b  which may allow fluid to escape during times of high back pressure.  
         [heading-0021]     Operation:  
         [0022]     Referring now to  FIGS. 1, 2 , and  4 , the operation of the filling and circulating tool  10  will now be discussed. The upper connecting sub  14  of the filling and circulating tool  10  may be connected to a work string (not shown). Before insertion into the casing, filling and circulating tool  10  is in the closed position illustrated in  FIGS. 1 and 2 . The work string is then lowered into a well bore containing a casing  81  (shown in  FIGS. 2 and 4 ). When the scissor arms  54   a  and  54   b  engage the top opening  83  of the casing  81 , the scissor arms  54   a  and  54   b  laterally collapse inward towards the mandrel  24 . The lateral collapsing of the scissor arms  54   a  and  54   b  causes the scissor arms  54   a  and  54   b  to push longitudinally against the scissor sleeve  52 , which, in turn, causes the scissor sleeve  52  to move in a first direction  85  along the mandrel  24  towards the upper connecting sub  14 .  
         [0023]     As the scissor sleeve  52  moves in the first direction  85 , it pulls the valve sleeve  32  in the first direction  85  via the connecting rods  60   a  and  60   b . Thus, the valve sleeve  32  is pulled from a closed position to an open position (as illustrated in  FIG. 4 ). In moving from the closed to open position, the valve sleeve  32  moves longitudinally in the first direction  85  along the mandrel  24  towards the top end of the upper connecting sub  14 .  
         [0024]     As the valve sleeve  32  moves from the closed position to the open position, the fluid ports  30  become exposed as illustrated in  FIG. 4 . Drilling fluids may now be circulated through the filling and circulating tool  10  as it is lowered into the casing. The fluids enter through the top opening  16  ( FIG. 1 ) of the upper connecting sub  14 . The fluids may flow through the central throughbore  18 , and exit through the fluid ports  30   a  through  30   d.    
         [0025]     At some point, it may be desirable to remove the work string from the wellbore. Upon removal of the tool string, the filling and circulating tool  10  is lifted by the top connecting sub  14 . When the scissor arms  54   a  and  54   b  move past the top opening  83  of the casing  81 , the weight of the scissor sleeve  52  and the valve sleeve  32  push down on the scissor arms  54   a  and  54   b , causing them to expand laterally, as illustrated in  FIG. 2 . This lateral expansion of the scissor arms  54   a  and  54   b  allows the scissor sleeve  52  to move longitudinally in a second direction  87  along the mandrel  24  towards the nose guide  34 .  
         [0026]     As the scissor sleeve  52  moves in the second direction  87 , it also allows the valve sleeve  32  to move in the second direction  87 . Thus, the valve sleeve  32  moves back from the open position illustrated in  FIG. 4  to the closed position as illustrated in  FIG. 2 . The plurality of 0-rings  68  ( FIG. 3   a  maintains a fluid-tight seal so that the fluids do not leak from the filling and circulating tool  10  as the tool is lifted from the casing opening  83 .  
         [0027]     With conventional filling and circulating tools, if a fluid pump (not shown) is left on for too long during the removal process, back pressure will develop within the tool string and the filling and circulating tool  10 . The back pressure is undesirable and may result in an unsafe condition. Turning back to  FIGS. 3   a  and  3   b  if high back pressure occurs while using the filling and circulating tool  10 , the pressure in the throughbore  18  will overcome the biasing force exerted on the ball  74  by the spring  75  or the plunger  96  by the helical spring  98 , causing the ball  74  or plunger  96  to move longitudinally down the fluid passage  72  or  94 , respectively. Once the ball is away from the neck  70 , fluid may flow around the ball  74  down through the fluid passage  72 . The fluid may exit through the fluid passages  36   a  and  36   b  or  108   a  and  108   b , respectively, thereby relieving any excessive back pressure building in the central throughbore  18 .  
         [0028]     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many other modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.