Abstract:
The apparatus for uninterrupted flushing a well bore being drilled with a jointed drill string comprises a continuous flushing valve (CFV) and a connector for temporarily attaching a bypass line to the valve. The CFV is a ball-type three way valve in a housing adapted for including in the drill string. Inside the housing there are two axial and two side sealing seats which provide for flow only through designated paths. The plug is prevented from loosening by a spring. An operating stem is mounted to operate the valve by a wrench from outside the housing. A connector facilitates fast tying a hose of a bypass line to the side port. A securing mechanism keeps a valve ball in full open position while a CFV is in the well.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit Of the earlier filing date of provisional application No. 61/072,117 filed Mar. 28, 2008, and entitled “An Apparatus for uninterrupted flushing a well bore”. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to apparatus for drilling a well bore into the earth using a system comprising a drilling rig with a top drive/kelly or a downhole motor for rotating the drill string comprising interconnected joints of drill pipe. More close, it relates to apparatus for uninterrupted flushing a well bore while a drill pipe joint is being added to or removed from drill string. More particularly it relates to apparatus in systems which use for uninterrupted flushing a plurality of valves being included in the drillstring for temporarily bypassing flushing fluid flow while making a connection. 
         [0004]    2. Description of Related Art 
         [0005]    In drilling, as the operation continues, it is necessary to add sections of drill pipe, during which time in conventional drilling circulation of drilling fluid must be discontinued. It leads to several complications in the well bore and lost of time. 
         [0006]    For many years drilling industry is working on technical solutions which could provide for uninterrupted flushing a well bore while making a drill string connection. 
         [0007]    The known continuous circulation methods and apparatus comprise two main groups. 
         [0008]    The first group deploys a plurality of continuous flushing valves also referred to as “drill string couplings,” “continuous circulation subs”, “continuous circulation valves”. The second group deploys for continuous circulation a dividable chamber sealed around drill pipe as it is disclosed in U.S. Pat. No. 3,559,739 to Hutchison. 
         [0009]    The present invention relates to the first group. 
         [0010]    U.S. Pat. No 1,491,986 to Greene discloses a valve assembly, a continuous circulation coupling comprising housing adopted for including in the drill string as a sub such that every stand receives a valve assembly. A hinged flapper valve with two seats is placed inside the housing. The housing has a threaded side opening. The arrangement is such that the flap valve will normally cover the side opening but may pivot to close axial channel of the valve. Normally the side opening is covered with a plug. When it comes to making a connection, the plug is unscrewed from the valve body and a bypass line (a hose) is screwed into the side opening (side port). By operating appropriate valves on surface lines the direction of circulation is changed. Now the drilling fluid flows from the side port. Axial channel above the side port is sealed by the flap. The driving mechanism is disconnected from the drill string. A new drill pipe stand is added to the drill string. Again, by operating appropriate valves the flow of the drilling fluid is diverted to normal axial direction; the bypass line is disconnected; the side port is sealed with the plug; and drilling is resumed. 
         [0011]    U.S. Pat. No. 2,158,356 to Dyer discloses some new features to the design of the flapper valve. 
         [0012]    U.S. Pat. No. 3,298,385 to Jackson et.el. (“Constant circulating coupling device”) pointed at a number of disadvantages inherent in the continuous circulating sub of the patent . . . 356. Patent . . . 385 discloses a continuous circulating sub with a one piece housing; a removable flapper valve; a bayonet-type lock between side port and bypass line and between the side port and a plug. 
         [0013]    UK patent GB 2 427 217 to Calderoni et. el. discloses a device which uses the same operational process as the devices of the above cited patents. But the device of the patent . . . 217 has two valves. Valve A closes and opens a side port. Valve B closes and opens the axial channel. In preferred embodiment, the valves are flapper-type (named in the patent “throttle”). No specifics concerning side port connecting mechanism and a plug (“safety plug”) of the side port are disclosed or claimed. 
         [0014]    An important issue with continuous flushing devices which deploy flapper-type valves is that drilling fluids flow through open seats of the valve. If drilling fluid is a mud composed of clay, barite, loss circulation additives these materials unevenly deposit on sealing surfaces. It may lead to partial closure of the valve, leaks, complications while drill string connection process and unsafe conditions on the rig floor. 
         [0015]    U.S. Pat. No. 7,308,952 to Strazhgorodskiy discloses a system for continuously flushing a wellbore while drilling and making drill string connections with direct or reverse circulation of a drilling fluid or with a formation fluid being produced through the drill string. The continuous flushing system of the . . . 952 deploys a ball valve. But the ball valve in preferred embodiment of . . . 952 may be difficult to manufacture and maintain. In addition, the valve of . . . 952 lacks a feature which would exclude unwonted movements of the valve ball while drilling. 
         [0016]    The incessant for almost hundred years, but with a few practical results, attempts to develop reliable apparatus for continuously flushing wells while making drill string connections, show the importance of the technology for the industry. 
         [0017]    3. Objects and Advantages 
         [0018]    An object of present invention is to provide an apparatus for continuously flushing a well bore while making drill string connections. More specifically, the apparatus using a ball-type valve which provides the possibility to drill with direct or reverse circulation, is contained in full open position while being in the well, has convenient means for connecting a bypass line to the side port, and which has supplementary safety features. 
       SUMMARY OF THE PRESENT INVENTION 
       [0019]    The apparatus of the invention comprises at least one continuous flushing valve (CFV) and a connector for temporarily attaching a line to the valve. 
         [0020]    The CFV has a housing adopted for including in a drill string as a sub. A three-way ball valve assembly is mounted inside the housing. The housing has a threaded side opening, which constitutes the side port of the valve. 
         [0021]    Inside the housing there are two axial and two side sealing seats which provide for flow only through designated paths. There are also some additional sealing means. 
         [0022]    An operating stem is mounted to operate the valve by a wrench from outside the housing. By rotating the stem the valve ball may be put in three positions, each of the positions providing two flow patterns. 
         [0023]    In first position a fluid may flow up and down through the valve. In the second position fluid may flow from side port downwards, and in the opposite direction. The third position provides for flow downwards to the side port and vice versa. 
         [0024]    For connecting a conduit, usually a hose, to the side port a special connector is provided. The connector comprises means which allow rotating a connecting pipe of connector while the hose is not rotating. 
         [0025]    While a CFV is in the well bore the side port is closed by the ball valve. A plug redundantly seals the side port. The plug has a thread which fits the thread of the side port of CFV, and sealing means which comprise O-rings. The plug is prevented from loosening by a spring or other means known in the art. 
         [0026]    It is not supposed to be, but a small volume of pressurized fluid may accumulate in space between the ball and plug. To avoid an injury with the plug, volume of space below the plug is minimized by the form and length of the plug. An additional safety feature is provided with means for releasing the pressure. The means comprise a venting channel. The venting channel may be a grove cut through part of the thread of the plug. 
         [0027]    For making the process of connecting and disconnecting a hose to and from the side port of the valve physically easier and safer, the connector may be mounted on a cart. The cart takes the load of the connector and adjacent part of the hose. The cart comprises known in the art means for adjusting its height such that connecting pipe may be placed in an appropriate position. 
         [0028]    While drilling a well bore the drill string is subjected to strong vibration. A securing mechanism is provided for preventing the ball valve from rotating under vibration forces. The securing mechanism comprises a short stem at the bottom of the plug and a notch at the surface of the ball valve. When the plug is screwed into side port closed by the valve ball, plug&#39;s locking stem is placed into the notch of the ball. 
         [0029]    Making a connection with CFV in drilling with direct circulation comprises follow steps. The upper most CFV is placed above rotary table. The side port plug is unscrewed. A bypass line is connected to the side port and pressurized with drilling fluid. The valve ball of the CFV is put in the second position to permit the flow of drilling fluid from the bypass line. Flow of drilling fluid from the main line is discontinued. Rotating mechanism is disconnected from drill pipe. New drill pipe stand, generally with a CFV at its head, is added to drill string and pressurized with drilling fluid. The valve ball is turned into the first position. Drilling fluid flow from the bypass line is discontinued. Bypass line is disconnected from the side port. The plug is put in place. Drilling resumes. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]    The invention is illustrated in the accompanying drawing in which: 
           [0031]      FIG. 1  is a general view of the Apparatus 
           [0032]      FIG. 2  is a partially sectional view of a connector 
           [0033]      FIG. 3  is a sectional view of a continuous flushing valve 
           [0034]      FIG. 4  is an exploded view a continuous flushing valve 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    The present invention relates to apparatus in systems which use for uninterrupted flushing a plurality of three-way ball valves being included in the drillstring for temporarily bypassing flushing fluid flow while making a drill string connection. 
         [0036]    Referring to  FIG. 1 , there is a general view of the apparatus in position after a drill pipe joint is added to the drill string. A continuous flushing valve (CFV)  100  is connected to the uppermost pipe joint  2  of the drillstring. A new drill pipe joint  3  is connected to CFV  100 . A bypass line (hose)  4  with flange  5  is connected to a side port  115  via a connector  200 . The connector  200  comprises a first pipe  202  with a handle  203  and a second pipe  204 . 
         [0037]    The connector  200  is mounted on a cart  250 . The cart has means  260  for adjusting its height and may be moved on rig floor  8  to and from rotary table  10 . 
         [0038]      FIG. 2  shows a connector  200  in more inclusive form. A pipe  202  has threaded end  206  which fits threaded side port  115  of the continuous flushing valve ( FIG. 1 ). O-ring  216  seals the connection. There is an outside threaded middle part  210  of the pipe  202 . A part  207  of the pipe  202  is not threaded, has an O-ring  208  and may slide inside a pipe  204 . The pipe  204  has an inside threaded end  212  which fits thread  210  of the pipe  202 . A flange  214  has a plurality of bolt openings  215  for connecting with a flange of a hose. 
         [0039]    The pipe  202  is being screwed or unscrewed into or from the side port by rotating the pipe  202  with a handle  203 . The pipe  202  rotates inside the pipe  204 . The pipe  204  does not rotate. 
         [0040]      FIG. 3  is a cross-sectional view of the continuous flushing valve (CFV)  100 . The major components of the CFV  100  are a housing  110 , a valve ball  120 , a lower seat assembly  130 , an upper seat assembly  140 , an open side seat (open cheek)  150 , a side seat (death cheek)  155 , a holder  160 , a locking assembly  170 , and a plug assembly  300 . 
         [0041]    The housing  110  is designed as a sub with threaded pin  111  and box  112  ends which fit drill pipe connections. The housing  110  includes an upper passage section  113  and a lower passage section  114  with a shoulder  117 , a threaded hole of side port  115 , and a recess  116 . 
         [0042]    The valve ball  120  has an axial (through) hole  122  and a transverse hole  124 . The holes  142 ,  144  form two connected cylindrical passages, a conventional combination for 3-way ball type valves. The valve ball has a closing sector  126  with a notch  128 . 
         [0043]    The cheeks  150 , 155  and the valve ball  120  are mounted together by a holder  160 . The assembly is kept in place with spring rings  161  and  163  which fit into appropriate groves. 
         [0044]    The force of a wave spring  144  applies to the upper seat  140   120  and helps to keep the valve ball  120  in sealing contact with the upper seat  120  and the lower seat  130 . 
         [0045]    Those having ordinary skill in the art will appreciate that other biasing mechanisms, such as Beliville washers, helical springs, and elastomeric material, may be used instead of a wave spring without departing from the scope of the present invention. 
         [0046]    An O-ring  132  is placed into a groove to seal around the lower seat  130 . An O-ring  142  is placed into a groove to seal the around the upper seat  140 . The O-rings  132 ,  122  prevent fluid from bypassing the ball valve assembly into or from the upper passage section  113  and a lower passage section  114 . 
         [0047]    Outer surfaces of the cheeks  150  and  155  correspond (fit) to the surface of the cylindrical section  113  of the housing  110  to provide sealing contacts. 
         [0048]    A threaded side port  115  may be sealed with a plug assembly  300  or it may be used for temporarily securing the first pipe  202  of the connector  200  as it is shown on  FIG. 1 . 
         [0049]    The plug assembly  300  may comprise a threaded plug  302 , a wrench opening  308 , a venting grove  316 , an O-ring  314 , a locking stem  310 . When the plug is screwed into the opening  115  of the side port the closing part  126  of the valve ball  120  is in position against side port. The stem  310  is placed into locking opening  128  of the valve ball to secure its position. The opening  152  of the open cheek  150  ( FIG. 4 ) is sealed by the closing part  126  of the valve ball  120 . Multiple sealing barriers of the valve assembly  102 , disclosed above, provide for effective sealing of the side port  115 . Only negligible volume of fluids may accumulate below the plug  302 . By one turn of the plug, the O-ring  314  unseals the path through grove the grove  316 . After releasing the pressure the plug may be safely unscrewed. 
         [0050]    The ball valve assembly  102  is retained in the housing  110  by a securing mechanism comprising a split ring  182 , a support ring  184 , and a snap ring  107 . The split ring  105 , which may include a plurality of ring segments, is received into groove  116  of the housing  110 . The split ring  182  segments may be placed down into the passage  116  above an intermediate ring  146  one at a time, and then moved radially outward into the groove  116 . After the segments of the split ring  182  are in the groove  116 , the support ring  184  is placed to be radially inside of the split ring  182 . The support ring  184  helps to prevent the segments of the split ring  182  from moving radially inward. A snap ring  185  may be used to fix the support ring  184  in place. The snap ring  185  is radially compressed, placed in alignment with the groove  186  in the split ring  182 , and released to radially expand into groove  186 . Those having ordinary skill in the art will appreciate that other securing mechanisms, such as set screw, may be used instead of the snap ring  185  without departing from the scope of the present invention. 
         [0051]      FIG. 4  is an isometric exploded view of the continuous flushing valve  100  and provides the possibility to show some details, which could not be seen on  FIG. 2 , and to explain an assembling process. 
         [0052]    A housing  110  has a threaded pin end  111  and a threaded box end  112 . A threaded opening  115  may be closed with a plug assembly  300  which comprises a plug  302  with an O-ring  314 , a spring  318 , and an O-ring  314 . The plug has a wrench opening  308  and a locking stem  310 . 
         [0053]    An opening  118  receives an operating stem assembly  170 . The stem assembly comprises a tong  172 , a wrench opening  174 , an O-ring  176 . 
         [0054]    The valve ball  120  has an axial opening  122  and a transverse opening  124 . The tong  172  of the stem fits into a groove  126  of a valve ball  120  such that the valve ball may be operated by rotating the stem  170  with a wrench (not shown). 
         [0055]    An O-ring  132  fits into a recess  134  of a lower seat  130 . 
         [0056]    A holder  160  has windows which are adapted to host an open side sealing seat  150  and a death side sealing seat  155 . A stem opening  166  is located transverse to the windows. The stem opening  166  is of width which fits to a width of the tong  172  of the operating stem  170 . A disk  168  limits transverse movements of a valve ball  120  inside the holder. A groove  162  and a groove  164  of the holder are in alignment with grooves  154 , 156  of an open side seat  150 , and appropriate grooves of the death side seat  155 . Spring rings  161 , 163  fit into the grooves of the holder  160  and the side seats  150  and  155 . 
         [0057]    An O-ring  142  fits into a recess  144  of an upper seat  140 . 
         [0058]    Other parts will be shown along with a mounting process. 
         [0059]    The lower seat  130  with the O-ring in a recess  134  is placed on a shoulder  117  of the housing  110 . The operating stem assembly  170  is placed into an opening  118  of the housing  110 , with a tong  172  positioned along the axis of the housing. The valve ball  120  is placed into the holder. The side seats  150  and  155  are put into the appropriate windows of the holder. The spring rings  161  and  163  are placed into appropriate grooves of the holder  160  and site seats  150 ,  155  making up a holder assembly. The holder assembly is placed into the housing. The upper seat  140  is placed on the valve ball, followed by a wave spring  144  and a ring  146 . A split ring  182  is placed into the recess  116  of the housing  110 . A support ring  184  is placed to be radially inside the split ring. A snap ring  186  is placed into a groove  183  of the split ring  187 . The valve ball is put in axial flow position, with site port closed as it is shown on  FIG. 2 . At the end, the plug  302  is screwed into the side port  115 . Continuous flushing valve is in position shown on  FIG. 2   
         [0060]    Those skilled in the art will appreciate that there may be other embodiments of the invention which do not depart from the scope of the invention as disclosed herein. The housing of the valve may be made from two parts, the side sealing seats may be placed in appropriate groves cut inside the housing, the sealing surfaces of seats may have O-rings, the outer surfaces of side seats may have means for enhanced sealing contacts, the connector may have not a flange, but other connecting means known in the art. In alternative embodiment, the plug assembly may have a venting valve. The scope of the invention should be limited only by the attached claims.