Hybrid drill bit

Abstract

A method for optimizing drill bit design and several embodiments of an optimized drill bit for drilling a well in an earth formation. In one embodiment, the optimized drill bit comprises a diamond impregnated bit body with one or more cutting elements, the cutting element comprising a cutting table and a substrate. The substrate preferably comprises a material that will support the cutting table during normal drilling operations and wear when exposed to the earth formation, thereby limiting the effects of wear flat areas on drilling efficiency. Alternatively, or additionally, the cutting elements may be placed, or spaced, so as to limiting the effects of wear flat areas on drilling efficiency.

1 . A method of designing a drill bit, such as for drilling into an earth formation, the method comprising the steps of:
 configuring the drill bit with a diamond impregnated bit body and at least one cutting element, the cutting element comprising a cutting table and a substrate; and   selecting a material for the substrate so that the substrate will support the cutting table during normal drilling operations and wear when exposed to the earth formation, thereby limiting the effects of wear flat areas on drilling efficiency.   
   
   
       2 . The method as set forth in  claim 1 , wherein the cutting table is operable to cut the earth formation. 
   
   
       3 . The method as set forth in  claim 1 , wherein the bit body is operable to cut the earth formation. 
   
   
       4 . The method as set forth in  claim 1 , wherein the cutting table has an abrasion resistance greater than the earth formation. 
   
   
       5 . The method as set forth in  claim 1 , wherein the bit body has an abrasion resistance greater than the earth formation. 
   
   
       6 . The method as set forth in  claim 1 , wherein the substrate has an abrasion resistance less than the earth formation. 
   
   
       7 . The method as set forth in  claim 1 , wherein the substrate has an abrasion resistance less than the cutting table. 
   
   
       8 . The method as set forth in  claim 1 , wherein the substrate has an abrasion resistance less than the bit body. 
   
   
       9 . The method as set forth in  claim 1 , further including the step of arranging a plurality of diamond impregnated cutting structures on the bit body. 
   
   
       10 . The method as set forth in  claim 1 , further including the step of arranging a plurality of diamond impregnated cutting structures among the cutting elements. 
   
   
       11 . A method of designing a drill bit, such as for drilling into an earth formation, the method comprising the steps of:
 configuring the drill bit with a diamond impregnated bit body and a plurality of cutting elements, the cutting element comprising a cutting table and a substrate; and   placing the cutting elements on the bit body to limit the effects of wear flat areas on drilling efficiency.   
   
   
       12 . The method as set forth in  claim 11 , wherein the cutting elements are spaced tighter in a shoulder section of the bit body. 
   
   
       13 . The method as set forth in  claim 11 , wherein the cutting elements are spaced tighter in a nose section of the bit body. 
   
   
       14 . The method as set forth in  claim 11 , wherein the cutting elements have greater spacing in a cone section of the bit body. 
   
   
       15 . The method as set forth in  claim 11 , wherein the cutting elements have greater spacing in a gage section of the bit body. 
   
   
       16 . The method as set forth in  claim 11 , further including the step of arranging a plurality of diamond impregnated cutting structures on the bit body. 
   
   
       17 . The method as set forth in  claim 11 , further including the step of arranging a plurality of diamond impregnated cutting structures among the cutting elements. 
   
   
       18 . A method of designing a drill bit, such as for drilling into an earth formation, the method comprising the steps of:
 configuring the drill bit with a diamond impregnated bit body a plurality of diamond impregnated cutting structures and a plurality of cutting elements, each cutting elements comprising a cutting table and a substrate;   selecting a material for the substrate so that the substrate will support the cutting table during normal drilling operations and wear when exposed to the earth formation, thereby limiting the effects of wear flat areas on drilling efficiency; and   placing the cutting elements on the bit body to limit the effects of wear flat areas on drilling efficiency.   
   
   
       19 . The method as set forth in  claim 18 , wherein both the cutting table and the bit body are operable to cut the earth formation, while the substrate has an abrasion resistance less than the cutting table, the bit body and the earth formation. 
   
   
       20 . The method as set forth in  claim 18 , wherein the cutting elements are spaced tighter in a shoulder section and a nose section than in a cone section or a gage section of the bit body.