Methods of designing and forming earth-boring tools using a plurality of depth of cut values

Abstract

Methods of designing an earth-boring tool are described, including calculating one or more performance parameters of the tool based on drilling conditions, a plurality of depth of cut values, and a set of values of other design variables. Methods of enhancing a performance parameter in the design of an earth-boring tool are also described, including calculating the performance parameter based at least partially on a plurality of depth of cut values and a first set of values of other design variables, calculating the performance parameter based at least partially on a second set of values of the other design variables different than the first set, and comparing the calculated performance parameters to determine which of the first and the second set is closer to a target range or value across a range of the plurality of depths of cut. Related methods of forming an earth-boring tool are also described.

What is claimed is: 
     
         1 . A method of forming an earth-boring tool, comprising:
 designing the earth-boring tool, comprising:
 using a computer to calculate torque values for each blade of a plurality of blades of the earth-boring tool as a function of drilling conditions, a plurality of values of a depth of cut variable, and a first set of values of other design variables for the earth-boring tool; 
 using the calculated torque values for each blade of the plurality of blades of the earth-boring tool and selecting at least one of the values of the first set of values of the other design variables for incorporation into a computer model of the earth-boring tool; and 
 generating the computer model of the earth-boring tool based in part on the selected at least one of the values of the first set of values of the other design variables; and 
   fabricating the earth-boring tool based at least in part on the generated computer model of the earth-boring tool.   
     
     
         2 . The method of  claim 1 , further comprising defining values for the drilling conditions and inputting the values for the drilling conditions into the computer. 
     
     
         3 . The method of  claim 2 , wherein defining values for the drilling conditions comprises defining values for drilling conditions based on characteristics of a drilling system that will incorporate the earth-boring tool. 
     
     
         4 . The method of  claim 3 , wherein defining values for the drilling conditions comprises defining values for at least one of maximum torque, bit rotation speeds, and weight-on-bit. 
     
     
         5 . The method of  claim 2 , wherein defining values for the drilling conditions comprises defining values for drilling conditions based on characteristics of a formation to be drilled using the earth-boring tool. 
     
     
         6 . The method of  claim 5 , wherein defining values for the drilling conditions comprises defining values for at least one of formation hardness, angle at which the earth-boring tool will proceed through the formation, offset of the earth-boring tool from a borehole centerline, earth-boring tool tilt, earth-boring tool side load, and type of formation to be drilled. 
     
     
         7 . The method of  claim 1 , wherein using the calculated torque values for each blade of the plurality of blades of the earth-boring tool and selecting at least one of the values of the first set of values of the other design variables for incorporation into a computer model of the earth-boring tool comprises selecting all of the first set of values of the other design variables for incorporation into the computer model of the earth-boring tool. 
     
     
         8 . The method of  claim 1 , wherein using a computer to calculate torque values for each blade of a plurality of blades of the earth-boring tool as a function of drilling conditions, a plurality of values of a depth of cut variable, and a first set of values of other design variables for the earth-boring tool comprises using the computer to calculate torque values for each blade of a plurality of blades of the earth-boring tool as a function of respective values of at least one of cutter size, cutter shape, cutter placement, cutter rake angle, color composition, number of cutters, cutter chamfer configuration, number of blades, size of blades, blade angle, blade spacing, bit profile, cone angle, bit composition, junk slot area, wear state, nozzle size, number of nozzles, location of nozzles, number of backup cutters, location of backup cutters, or exposure of backup cutters. 
     
     
         9 . The method of  claim 1 , wherein the designing and fabricating the earth-boring tool comprises designing and fabricating a fixed-cutter rotary drill bit. 
     
     
         10 . The method of  claim 1 , wherein using a computer to calculate torque values comprises:
 selecting a first value of the depth of cut variable;   calculating first torque values at the first value of the depth of cut variable;   selecting a second value of the depth of cut variable;   calculating second torque values at the second value of the depth of cut variable; and   determining whether the first torque values or the second torque values are closer to target torque values.   
     
     
         11 . The method of  claim 1 , further comprising determining whether the calculated torque values for each blade of a plurality of blades are within an acceptable range of a plurality of target torque values determined at the plurality of values of a depth of cut variable. 
     
     
         12 . The method of  claim 11 , wherein determining whether the calculated torque values for each blade of a plurality of blades are within an acceptable range comprises determining whether the calculated torque values for each blade are within a range defined by an operator of the computer. 
     
     
         13 . The method of  claim 12 , wherein determining whether the calculated torque values for each blade of a plurality of blades are within an acceptable range further comprises determining whether the calculated torque values for each blade are within a range defined by capabilities of a drilling system that will include the earth-boring tool. 
     
     
         14 . The method of  claim 11 , further comprising determining the acceptable range by determining at least the plurality of target torque values for each blade of the plurality of blades, manufacturing feasibility of the earth-boring tool, capabilities of a drilling system incorporating the earth-boring tool, and cost of fabricating the earth-boring tool. 
     
     
         15 . The method of  claim 1 , further comprising using the torque values for each blade of the plurality of blades to generate a plurality of torque curves using the computer. 
     
     
         16 . The method of  claim 15 , further comprising using the computer to generate a plot of the plurality of torque curves at the respective plurality of values of the depth of cut variable and the first set of values of the other design variables. 
     
     
         17 . A method of forming an earth-boring tool, the method comprising:
 designing the earth-boring tool to exhibit a net imbalance force when in operation, comprising:
 defining drilling conditions and inputting the drilling conditions into a computer; 
 using the computer to generate at least a first output of a performance parameter as a function of a plurality of values of a depth of cut variable, a first set of values of other design variables, and the drilling conditions to result in the net imbalance force of an earth-boring tool; 
 determining whether the at least a first output is within an acceptable range of a plurality of target performance parameter values determined at the plurality of values of a depth of cut variable to result in the net imbalance force; 
 using the at least a first output and selecting at least one of the values of the first set of values of the other design variables for incorporation into a computer model of the earth-boring tool; and 
 generating the computer model of the earth-boring tool based in part on the selected at least one of the values of the first set of values of the other design variables; and 
   fabricating the earth-boring tool based at least in part on the generated model of the earth-boring tool.   
     
     
         18 . The method of  claim 17 , wherein using a computer to generate at least a first output of a performance parameter comprises using the computer to generate an output of a performance parameter selected from the group consisting of a force, an imbalance force, a dynamic stability, a rate of penetration, an area of cut, a torque, and a torque curve of the earth-boring drill bit. 
     
     
         19 . The method of  claim 17 , further comprising:
 using a computer to generate at least a second output of the performance parameter of an earth-boring tool as a function of the plurality of values of the depth of cut variable and a second set of values of the other design variables different from the first set of values of the other design variables to result in the net imbalance force;   determining whether the at least a second output is within an acceptable range of the plurality of target performance parameter values determined at the plurality of values of a depth of cut variable to result in the net imbalance force;   comparing the at least a first output and the at least a second output;   selecting at least one of the values of the second set of values of the other design variables for incorporation into the computer model of the earth-boring tool; and   generating the computer model of the earth-boring tool based in part on the selected at least one of the values of the first set of values of the other design variables, the selected at least one of the values of the second set of values of the other design variables, and the comparison of the at least a first output and the at least a second output.   
     
     
         20 . The method of  claim 19 , wherein using a computer to generate at least a second output of the performance parameter comprises using the computer to generate an output of a performance parameter selected from the group consisting of a force, an imbalance force, a dynamic stability, a rate of penetration, an area of cut, a torque, and a torque curve of the earth-boring drill bit.