Pdc drill bit with cutter design optimized with dynamic centerline analysis and having dynamic centerline trajectory

Abstract

A method for designing a fixed cutter drill bit includes simulating the fixed cutter drill bit drilling in an earth formation, determining a dynamic centerline trajectory of the drill bit, and adjusting at least one design parameter based upon the graphical display of at least the dynamic centerline trajectory. To improve performance, the method can include graphically displaying the dynamic centerline trajectory and/or repeating the simulating, determining, displaying and adjusting to change a simulated performance of the fixed cutter drill bit. A drill bit design may be selected and a drill bit may be made according to the design resulting from the method of designing.

What is claimed is: 
     
         1 . A method of simulating drilling performance, comprising:
 predicting a side contact between a drilling tool assembly and a wellbore, the drilling tool assembly disposed on a drill string at a distal end thereof;   predicting a response of the drilling tool assembly;   predicting axial, torsional, and lateral vibrations; and   presenting a graphical representation of the wellbore being drilled.   
     
     
         2 . The method of  claim 2 , further comprising predicting at least one of torque, bending moments, wellbore geometry, velocity, acceleration, position, dynamic weight on bit, imbalance forces, contact forces, cutting element forces, resulting cutter wear, blade forces, blade contact points, and bit contact points at any point on the drill string. 
     
     
         3 . The method of  claim 3 , wherein presenting the graphical representation of the wellbore being drilled comprises displaying at least one of torque, bending moments, wellbore geometry, velocity, acceleration, position, dynamic weight on bit, imbalance forces, contact forces, cutting element forces, resulting cutter wear, blade forces, blade contact points, and bit contact points at any point on the drill string. 
     
     
         4 . A method of designing a drill bit, comprising:
 dynamically simulating the fixed cutter drill bit drilling in an earth formation for a period of time;   modeling a dynamic centerline trajectory of the simulated drill bit;   presenting the dynamic centerline trajectory, wherein the dynamic centerline trajectory comprises a lobe proceeding in a direction opposite a direction of drill bit rotation; and   adjusting a drill bit design parameter based on the dynamic centerline trajectory.   
     
     
         5 . The method of  claim 4 , wherein adjusting the drill bit design parameter comprises adjusting a value of the drill bit design parameter to change the dynamic centerline trajectory. 
     
     
         6 . The method of  claim 5 , further comprising modeling and presenting a modified dynamic centerline based on the adjusted drill bit design parameter. 
     
     
         7 . The method of  claim 6 , wherein the modified dynamic centerline trajectory comprises the protruding lobe proceeding in a same direction as the direction of drill bit rotation. 
     
     
         8 . The method of  claim 4 , wherein the drill bit design parameters comprise at least one of number of cutters, bit cutting profile, position of cutters on drill bit blades, bit axis offset of the cutter, bit diameter, cutter radius on bit, cutter vertical height on bit, cutter inclination angle on bit, cutter body shape, cutter size, cutter height, cutter diameter, cutter orientation, cutter back rake angle, cutter side rake angle, working surface shape, working surface orientation, bevel size, bevel shape, bevel orientation, cutter hardness, PDC table thickness, and cutter wear model. 
     
     
         9 . The method of  claim 4 , wherein adjusting the value of the at least one design parameter comprises adjusting the at least one parameter to decrease the maximum deviation of the dynamic centerline trajectory. 
     
     
         10 . The method of  claim 4 , wherein adjusting the value of the at least one design parameter comprises adjusting the at least one parameter to produce a dynamic centerline trajectory having a forward whirl. 
     
     
         11 . The method of  claim 4 , further comprising: adjusting a value of at least one design parameter to decrease the total imbalance force over the simulated period of drilling time. 
     
     
         12 . The method of  claim 4 , wherein a drill bit design is selected according to the adjusted drill bit parameter. 
     
     
         13 . The method of  claim 4 , further comprising repeating the simulating, modeling, presenting, and adjusting to change a simulated performance of the drill bit. 
     
     
         14 . A method of predicting drill string performance, comprising:
 coupling a bottom-hole assembly (BHA) and a drill bit model to obtain a drilling tool assembly model;   predicting a resulting borehole trajectory based on the drilling tool assembly model;   predicting bending moments of the drilling tool assembly model; and   predicting drilling tool assembly model deformation.   
     
     
         15 . The method of  claim 14 , wherein predicting bending moments of the drilling tool assembly model comprises predicting bending moments at any point on the drill bit model or BHA. 
     
     
         16 . The method of  claim 14 , wherein predicting drilling tool assembly deformation comprises predicting deformation at any point on the drill bit model or BHA. 
     
     
         17 . The method of  claim 14 , further comprising presenting a graphical representation of the resulting borehole trajectory. 
     
     
         18 . The method of  claim 17 , wherein the graphical representation of the borehole trajectory includes a graphical representation of the predicted bending moments and the predicted deformation. 
     
     
         19 . The method of  claim 14 , further comprising predicting at least one of axial, torsional, and lateral vibrations. 
     
     
         20 . The method of  claim 14 , further comprising predicting at least one of bit whirl and bending stresses at any point on the drilling tool assembly model.