Critical downhole torque of a drilling system and bit design to mitigate hfto

Abstract

Disclosed herein are embodiments of a method and system for determining a critical torque on bit to reduce the occurrence of high frequency torsional oscillation (HFTO). In one embodiment, a method includes detecting at least one drilling parameter of an offset drill bit for a type of drilling system during an offset drilling operation using at least one in-bit sensor; determining a critical torque on bit (TOB) that is to excite HFTO of the offset drill bit based on the at least one drilling parameter and based on the type of drilling system; measuring, for a current drilling operation, a current TOB and a current weight on bit (WOB) of a current drill bit having a same type of drilling system as the type of drilling system for the offset drilling operation; determining whether current TOB exceeds critical TOB; and mitigating the HFTO for the current drill bit.

What is claimed is: 
     
         1 . A method comprising:
 detecting at least one drilling parameter of an offset drill bit for a type of drilling system of a number of drilling systems during an offset drilling operation of a wellbore using at least one in-bit sensor in the offset drill bit;   determining a critical torque on bit (TOB) that is to excite a high frequency torque oscillation (HFTO) of the offset drill bit based on the at least one drilling parameter and based on the type of drilling system;   measuring, for a current drilling operation, a current TOB and a current weight on bit (WOB) of a current drill bit having a same type of drilling system as the type of drilling system for the offset drilling operation;   determining whether the current TOB exceeds the critical TOB; and   in response to determining that the current TOB exceeds the critical TOB, mitigating the HFTO for the current drill bit for the current drilling operation.   
     
     
         2 . The method according to  claim 1 , wherein mitigating the HFTO includes reducing the current WOB until the current TOB is below the critical TOB in the current drilling operation. 
     
     
         3 . The method according to  claim 1 , wherein mitigating the HFTO includes adjusting a drill bit design of the current drill bit while the current drill bit remains downhole in the wellbore. 
     
     
         4 . The method according to  claim 3 , wherein adjusting the drill bit design while the current drill bit remains downhole includes moving elements of the current drill bit to change a depth of cut. 
     
     
         5 . The method according to  claim 4 , wherein moving elements of the current drill bit include moving cutting elements to affect axial movement of the current drill bit. 
     
     
         6 . The method according to  claim 1 , wherein the at least one drilling parameter of an offset drill bit is one of drilling depth, depth of cut, angle of cut, type of formation, bit dull severity, rotations per measure of time, WOB, TOB, bend on bit (BOB) and rate of penetration. 
     
     
         7 . The method according to  claim 1 , wherein determining the critical TOB comprises determining a drilling depth at which HFTO occurred, calculating a scaled WOB, and calculating a scaled TOB. 
     
     
         8 . The method according to  claim 7 , wherein calculating the scaled WOB includes calculating an axial stiffness of a bottom hole assembly of the same type of drilling system as the type of drilling system for the offset drilling operation and the scaled WOB is a function of measure WOB and the axial stiffness of the bottom hole assembly. 
     
     
         9 . The method according to  claim 7 , wherein calculating the scaled TOB includes calculating a torsional stiffness of a bottom hole assembly of the same type of drilling system as the type of drilling system for the offset drilling operation and the scaled TOB is a function of measure TOB and the torsional stiffness of the bottom hole assembly. 
     
     
         10 . A non-transitory, computer-readable medium having instructions stored thereon that are executable by a processor to perform operations comprising:
 detecting at least one drilling parameter of an offset drill bit for a type of drilling system of a number of drilling systems during an offset drilling operation of a wellbore using at least one in-bit sensor in the offset drill bit;   determining a critical torque on bit (TOB) that is to excite a high frequency torque oscillation (HFTO) of the offset drill bit based on the at least one drilling parameter and based on the type of drilling system;   determining a weight on bit (WOB) and rotations per unit of time of the offset drill bit during the offset drilling operation;   selecting a drill bit design based on the determined critical TOB, WOB, and rotations per unit of time; and   constructing a drill bit for use in a drilling operation according to the selected drill bit design.   
     
     
         11 . The non-transitory, computer-readable medium according to  claim 10 , wherein the at least one drilling parameter of an offset drill bit is one of drilling depth, depth of cut, angle of cut, type of formation, bit dull severity, rotations per measure of time, WOB, BOB, TOB, and rate of penetration. 
     
     
         12 . The non-transitory, computer-readable medium according to  claim 10 , wherein determining the critical TOB comprises determining a drilling depth at which HFTO occurred, calculating a scaled WOB, and calculating a scaled critical TOB. 
     
     
         13 . The non-transitory, computer-readable medium according to  claim 12 , wherein calculating the scaled WOB includes calculating an axial stiffness of a bottom hole assembly of a same type of drilling system as the type of drilling system for the offset drilling operation and the scaled WOB is a function of measure WOB and the axial stiffness of the bottom hole assembly. 
     
     
         14 . The non-transitory, computer-readable medium according to  claim 12 , wherein calculating the scaled critical TOB includes calculating a torsional stiffness of a bottom hole assembly of a same type of drilling system as the type of drilling system for the offset drilling operation and the scaled critical TOB is a function of measure critical TOB and the torsional stiffness of the bottom hole assembly. 
     
     
         15 . The non-transitory, computer-readable medium according to  claim 10 , wherein selecting a drill bit design includes reviewing a stability map representing critical TOB versus WOB and including HFTO trigger points. 
     
     
         16 . The non-transitory, computer-readable medium according to  claim 15 , wherein the stability map represents scaled critical TOB and scaled WOB. 
     
     
         17 . A system comprising:
 a processor; and   a non-transitory computer-readable medium having instructions stored thereon that are executable by the processor to cause a drill bit design apparatus to:
 detect at least one drilling parameter of an offset drill bit for a type of drilling system of a number of drilling systems during an offset drilling operation of a wellbore using at least one in-bit sensor in the offset drill bit; 
 determine a critical torque on bit (TOB) that is to excite a high frequency torque oscillation (HFTO) of the offset drill bit based on the at least one drilling parameter and based on the type of drilling system; 
 determine a weight on bit (WOB) and rotations per unit of time of the offset drill bit during the offset drilling operation; and 
 select a drill bit design for construction of a drill for use in a drilling operation within a wellbore based on the determined critical TOB, WOB, and rotations per unit of time. 
   
     
     
         18 . The system according to  claim 17 ,
 wherein the instructions stored on the processor to cause the drill bit design apparatus to determine the critical TOB include instructions to cause the drill bit design apparatus to,
 determine a drilling depth at which HFTO occurred, 
 calculate a scaled WOB, and 
 calculate a scaled critical TOB. 
   
     
     
         19 . The system according to  claim 18 ,
 wherein the instructions to cause the drill bit design apparatus to calculate the scaled WOB includes instructions to cause the drill bit design apparatus to calculate an axial stiffness of a bottom hole assembly of a same type of drilling system as the type of drilling system for the offset drilling operation and the scaled WOB is a function of measure WOB and the axial stiffness of the bottom hole assembly, and   wherein the instructions to cause the drill bit design apparatus to calculate the scaled critical TOB includes instructions to cause the drill bit design apparatus to calculate a torsional stiffness of a bottom hole assembly of the same type of drilling system as the type of drilling system for the offset drilling operation and the scaled critical TOB is a function of measure critical TOB and the torsional stiffness of the bottom hole assembly.   
     
     
         20 . A method comprising:
 detecting at least one drilling parameter of a previous drill bit during a previous drilling operation of a wellbore using at least one in-bit sensor in the previous drill bit;   determining a critical torque on bit (TOB) that is to excite a high frequency torque oscillation of the previous drill bit during drilling based on the at least one drilling parameter and based on a class of drilling; and   developing a drill bit design criteria to mitigate high frequency torsional oscillations (HFTO), based at least in part on the determined critical torque on bit such that a torque of a subsequent drill bit during the subsequent drilling operation is less than the critical TOB; and   constructing the subsequent drill bit for use in a subsequent drilling operation in a wellbore based on the developed drill bit design criteria.   
     
     
         21 . The method according to  claim 20 , wherein the drill bit design criteria to mitigate the HFTO includes adjusting the previous drill bit while the previous drill bit remains downhole based on the class of drilling such that a torque of the previous drill bit during the subsequent drilling operation is less than the critical TOB. 
     
     
         22 . The method according to  claim 20 , wherein the drill bit design criteria to mitigate HFTO includes considering drilling efficiency of the previous drill bit. 
     
     
         23 . The method according to  claim 20 , wherein developing a drill bit design criteria to mitigate the HFTO includes reviewing critical TOB versus WOB and data points representing HFTO trigger points. 
     
     
         24 . A method comprising:
 measuring, for a drilling operation, a torque on bit (TOB) and weight on bit (WOB) of a drill bit in a drilling system;   identifying whether high frequency torsional oscillations (HFTO) occurred at a first drilling depth;   in response to identifying that HFTO occurred at the first drilling depth, recording the TOB as a critical TOB; and   adjusting WOB and rotations per unit of time for the drilling operation to reduce TOB not exceeding the critical TOB at a second drilling depth.   
     
     
         25 . The method of  claim 24 , further comprising selecting and constructing a drill bit design for a future drilling operation based on at least the critical TOB. 
     
     
         26 . The method according to  claim 24 , wherein the drilling system includes a processor and the processor is configured to identify whether the HFTO occurred at the first drilling depth, record the TOB as a critical TOB, and determine values for which to adjust the WOB and rotations per unit of time to reduce TOB to not exceed critical TOB at the second drilling depth.