Rotary Drill Bit

Abstract

A rotary drill bit ( 10 ) is provided for drilling a hole in a subsurface formation. The bit body ( 12 ) includes a plurality of axially extending ribs ( 16 a, b, c and d ) and a flow channel between adjacent ribs. A plurality of cutting elements ( 19 ) are fixedly mounting on a respective one of the plurality of ribs. A plurality of flow nozzles ( 20 a, b, c and d ) direct fluid to a respective one of the plurality of cutting elements to clean and cool the cutting elements.

1 . A rotary drill bit for drilling a hole in a subsurface formation, comprising:
 a bit body having a leading cutting face and outer peripheral edges, the bit body including a plurality of radially extending ribs with a flow channel between adjacent ribs, the bit body further including a bit body flow path radially inward of the peripheral edges;   a plurality of cutting elements each fixedly mounted on a respective one of the plurality of radially extending ribs; and   a plurality of flow nozzles each in fluid communication with the bit body flow path for directing fluid to a respective one of the plurality of cutting elements to clean and cool the cutting element.   
     
     
         2 . A rotary drill bit as defined in  claim 1 , wherein the plurality of cutting elements each mounted on a respective blade include face cutting elements for defining the leading cutting face substantially perpendicular to a bit centerline and side cutting elements adjacent the outer peripheral edges of the bit body. 
     
     
         3 . A rotary drill bit as defined in  claim 1 , further comprising:
 a manifold for receiving fluid flow from the bit body flow path and outputting flow through the plurality of flow nozzles to the respective plurality of cutting elements mounted on a respective rib.   
     
     
         4 . A rotary drill bit as defined in  claim 3 , wherein the manifold is provided for each of the plurality of radially extending ribs. 
     
     
         5 . A rotary drill bit as defined in  claim 3 , wherein the manifold positions each of the plurality of nozzles a substantially uniform distance from a respective cutting element. 
     
     
         6 . A rotary drill bit as defined in  claim 3 , wherein the manifold positions each of the plurality of nozzles an increasing distance from a respective cutting element as a function of an increasing radial distance of a respective cutting element from a centerline of the bit. 
     
     
         7 . A rotary drill bit as defined in  claim 3 , wherein the manifold is attached to the bit body. 
     
     
         8 . A rotary drill bit as defined in  claim 3 , wherein a sidewall of the manifold is provided on an insert attached to the bit body. 
     
     
         9 . A rotary drill bit as defined in  claim 1 , further comprising:
 a plurality of flow lines each extending from the bit body flow path to a respective one of the plurality of nozzles.   
     
     
         10 . A rotary drill bit as defined in  claim 1 , wherein a centerline of fluid flow from each nozzle is within 30° of a line passing through a central axis of the nozzle discharge port and a primary cutting surface on a respective cutting element. 
     
     
         11 . A rotary drill bit as defined in  claim 1 , wherein each nozzle has a mean diameter of from 3 mm to 20 mm. 
     
     
         12 . A rotary drill bit for drilling a hole in a subsurface formation, comprising:
 a bit body having a leading cutting face and outer peripheral edges, the bit body including a plurality of radially extending ribs with a flow channel between adjacent ribs, the bit body further including a bit body flow line within the bit body and radially inward of the peripheral edges;   a plurality of cutting elements each fixedly mounted on a respective one of the plurality of radially extending ribs; and   a plurality of discharge jets each in fluid communication with a respective bit body flow line for directing fluid to a respective one of the plurality of cutting elements to clean and cool the cutting element.   
     
     
         13 . A rotary drill bit as defined in  claim 12 , wherein the plurality of cutting elements each mounted on a respective blade include face cutting elements for defining the leading cutting face substantially perpendicular to a bit centerline and side cutting elements adjacent the outer peripheral edges of the bit body. 
     
     
         14 . A rotary drill bit as defined in  claim 12 , wherein a centerline of fluid flow from each jet is within 30° of a line passing through a central axis of the jet discharge port and a primary cutting surface on a respective cutting element. 
     
     
         15 . A rotary drill bit as defined in  claim 12 , wherein each jet directs fluid to a respective cutting element. 
     
     
         16 . A rotary drill bit as defined in  claim 12 , wherein each nozzle has a mean diameter of from 3 mm to 20 mm. 
     
     
         17 . A rotary drill bit as defined in  claim 12 , wherein flow through the plurality of jets creates a tangential force to assist in rotating the drill bit. 
     
     
         18 . A method of forming a drill bit for drilling a hole in a subsurface formation, comprising:
 providing a bit body having a plurality of radially extending ribs with a flow channel between adjacent ribs, the bit body further including a bit body flow path radially inward of its peripheral edges;   fixedly mounting a plurality of cutting elements on a respective one of the plurality of radially extending ribs; and   providing a plurality of discharge jets each in fluid communication with the bit body flow path for directing fluid to a respective one of the plurality of cutting elements.   
     
     
         19 . A method as defined in  claim 18 , wherein flow through the plurality of jets creates a tangential force to assist in rotating the drill bit. 
     
     
         20 . A method as defined in  claim 18 , wherein a centerline of fluid flow from each nozzle is within 30° of a line passing through a central axis of the nozzle discharge port and a primary cutting surface on a respective cutting element.