Pressure Relief nozzle

Abstract

A pressure relief nozzle installs on the face of a drill bit, and provides a flow path for drilling fluid. The pressure relief nozzle has a larger internal flow area when flow rates through the drill bit are high, and a smaller flow area when flow rates are low. Upon reduction of the pressure relief nozzle's internal flow area, the pressure drop across the drill bit tends to stabilize due to the reduced flow area through the drill bit.

1 . A pressure relief nozzle, comprising: 
 a hollow nozzle body having an upper end, a lower end, and an interior passage connecting said upper end to said lower end and defining a fluid flow path for fluid flowing through said interior passage;    a flow control member located in said fluid flow path, said flow control member movable between a first position and a second position, dependent upon a difference in fluid pressure of said fluid at said upper end and said lower end of said nozzle body.    
   
   
       2 . The pressure relief nozzle of  claim 1 , said upper end including means for connecting said nozzle body to a nozzle bore in a drill bit body.  
   
   
       3 . The pressure relief nozzle of  claim 1 , said first position being a fully open position and said second position being a fully closed position.  
   
   
       4 . The pressure relief nozzle of  claim 1 , said flow control member being a plug inserted in said nozzle body.  
   
   
       5 . The pressure relief nozzle of  claim 1 , said flow control member moving linearly with respect to said nozzle body to move from said first position to said second position.  
   
   
       6 . The pressure relief nozzle of  claim 1 , said flow control member moving laterally with respect to said nozzle body to move from said first position to said second position.  
   
   
       7 . The pressure relief nozzle of  claim 6 , said flow control member including a ramp.  
   
   
       8 . The pressure relief nozzle of  claim 6 , said flow control member including a sliding ramp.  
   
   
       9 . The pressure relief nozzle of  claim 6 , said flow control member including a first ramp and a second ramp.  
   
   
       10 . The pressure relief nozzle of  claim 6 , said flow control member including a first sliding ramp and a second sliding ramp.  
   
   
       11 . The pressure relief nozzle of  claim 1 , said first position allowing fluid flow through said pressure relief nozzle and said second position not allowing fluid flow through said pressure relief nozzle.  
   
   
       12 . The pressure relief nozzle of  claim 1 , said first position defining a first diameter for said interior passage and said second position defining a second diameter for said interior passage, said first diameter being larger than said second diameter.  
   
   
       13 . The pressure relief nozzle of  claim 1 , said flow control member being repeatedly movable from said first position to said second position, and from said second position to said first position.  
   
   
       14 . The pressure relief nozzle of  claim 13 , said first position defining a first diameter for said interior passage and said second position defining a second diameter for said interior passage, said first diameter being larger than said second diameter.  
   
   
       15 . The pressure relief nozzle of  claim 1 , said flow control member controlling a flow area for said fluid flow path, said first position providing a larger flow area than said second position.  
   
   
       16 . A method for operating a pressure relief nozzle, comprising; 
 installing a pressure relief nozzle to a drill bit body, said pressure relief nozzle having a fluid flow passage, said fluid flow passage having a first minimum diameter and a second minimum diameter dependent upon a pressure of fluid in said fluid flow passage, said first diameter being smaller than said second diameter;    opening said pressure relief nozzle from said first diameter to said second diameter; and    closing said pressure relief nozzle from said second diameter to said first diameter.    
   
   
       17 . The method of  claim 16 , further comprising: 
 re-opening said pressure relief nozzle.    
   
   
       18 . The method of  claim 17 , said pressure having an initial value and staying within ten percent of said initial value throughout said opening, closing, and re-opening steps.  
   
   
       19 . The method of  claim 17 , said pressure having an initial value and staying within five percent of said initial value throughout said opening, closing, and re-opening steps.  
   
   
       20 . The method of  claim 16 , further comprising: 
 installing a second pressure relief nozzle to said drill bit body; said second pressure relief nozzle having a second fluid flow passage, said second fluid flow passage having a first minimum diameter and a second minimum diameter dependent upon said pressure of fluid in said second fluid flow passage, said first diameter of said second fluid flow passage being smaller than said second diameter of said second fluid flow passage;    opening said second pressure relief nozzle from said first diameter to said second diameter; and    closing said second pressure relief nozzle from said second diameter to said first diameter.    
   
   
       21 . The method of  claim 16 , further comprising: 
 increasing fluid flow through said fluid flow passage from an initial flow value simultaneous with said opening step;    decreasing fluid flow through said fluid flow passage simultaneous with said closing step.    
   
   
       22 . A drill bit comprising: 
 a drill bit body;    a pressure relief nozzle installed into said drill bit body, said pressure relief nozzle comprising    hollow nozzle body having an upper end, a lower end, and an interior passage connecting said upper end to said lower end and defining a fluid flow path for fluid flowing through said interior passage;    a flow control member located in said fluid flow path, said flow control member movable between a first position and a second position, dependent upon a difference in fluid pressure of said fluid at said upper end and said lower end of said nozzle body.    
   
   
       23 . The drill bit of  claim 22 , further comprising: 
 a second pressure relief nozzle installed into said drill bit body, said second pressure relief nozzle comprising,    hollow nozzle body having an upper end, a lower end, and an interior passage connecting said upper end to said lower end and defining a fluid flow path for fluid flowing through said interior passage;    a flow control member located in said fluid flow path, said flow control member movable between a first position and a second position, dependent upon a difference in fluid pressure of said fluid at said upper end and said lower end of said nozzle body for said second pressure relief nozzle.    
   
   
       24 . The drill bit of  claim 22 , said first position being a fully open position and said second position being a fully closed position.  
   
   
       25 . The drill bit of  claim 22 , said flow control member being a plug inserted in said nozzle body.  
   
   
       26 . The drill bit of  claim 22 , said flow control member moving linearly with respect to said nozzle body to move from said first position to said second position.  
   
   
       27 . The drill bit of  claim 22 , said flow control member moving laterally with respect to said nozzle body to move from said first position to said second position.  
   
   
       28 . The drill bit of  claim 27 , said flow control member including a ramp.  
   
   
       29 . The drill bit of  claim 27 , said flow control member including a sliding ramp.  
   
   
       30 . The drill bit of  claim 27 , said flow control member including a first ramp and a second ramp.  
   
   
       31 . The drill bit of  claim 27 , said flow control member including a first sliding ramp and a second sliding ramp.  
   
   
       32 . The drill bit of  claim 22 , said first position allowing fluid flow through said pressure relief nozzle and said second position not allowing fluid flow through said pressure relief nozzle.  
   
   
       33 . The drill bit of  claim 22 , said first position defining a first diameter for said interior passage and said second position defining a second diameter for said interior passage, said first diameter being larger than said second diameter.  
   
   
       34 . The drill bit of  claim 22 , said flow control member being repeatedly movable from said first position to said second position, and from said second position to said first position.  
   
   
       35 . The drill bit of  claim 22 , said drill bit further comprising a second nozzle, said second nozzle having a hollow nozzle body with an upper end and a lower end connected by a flow path, there being a difference in fluid pressure between said upper end of said second nozzle and said lower end of said second nozzle, said flow path of said second nozzle having a constant flow area regardless of said pressure difference between said upper end of said second nozzle and said lower end of said second nozzle.