Calibrating friction factor and rock fracture properties

1 . A method for calibrating a model of a subterranean formation, the method comprising:

capturing one or more measurements at a surface of a wellbore that extends into the subterranean formation, wherein the one or more measurements comprise a surface torque (STOR) on a drill string that extends into the wellbore;

determining a friction factor based upon the STOR when a drill bit is off-bottom in the wellbore, wherein the drill bit is coupled to a lower end of the drill string;

determining a downhole torque on the drill bit (DTOR) and a downhole weight on the drill bit (DWOB) when the drill bit is on-bottom in the wellbore;

identifying a rock type in the subterranean formation based at least partially upon the friction factor, the DTOR, and the DWOB, wherein the one or more measurements also comprise a surface weight (SWOB) on the drill string, and wherein the DTOR and the DWOB are determined based upon the STOR, the SWOB, and the friction factor; and

performing a wellsite action in response to the rock type, wherein the wellsite action comprises varying the STOR, varying the SWOB on the drill string, varying a number of rotations per minute (RPM) of the drill string, varying a rate of penetration (ROP) of the drill string, or a combination thereof.

2 . The method of claim 1 , further comprising:

simulating the drill bit drilling on-bottom through a plurality of different rock types in the model to produce a plurality of simulated torques on the drill bit (BTORs), wherein the plurality of different rock types include the identified rock type; and

comparing the DTOR to the BTORs to produce a comparison, wherein the rock type is identified based upon the comparison.

3 . The method of claim 1 , further comprising:

simulating the drill bit drilling on-bottom through a plurality of different rock types in the model to produce a plurality of simulated weights on the drill bit (BWOBs), wherein the plurality of different rock types include the identified rock type; and

comparing the DWOB to the BWOBs to produce a comparison, wherein the rock type is identified based upon the comparison.

4 . The method of claim 1 , further comprising:

determining a simulated surface torque (STOR') on the drill string based upon the identified rock type;

comparing the STOR to the STOR' to produce a comparison; and

calibrating the friction factor based upon the comparison.

5 . The method of claim 1 , further comprising:

determining a simulated surface torque (STOR') on the drill string based upon the identified rock type;

comparing the STOR to the STOR' to produce a comparison; and

calibrating the rock type based upon the comparison.

6 . The method of claim 1 , further comprising:

determining a simulated surface weight (SWOB') on the drill string based upon the identified rock type;

comparing the SWOB to the SWOB' to produce a comparison; and

calibrating the friction factor based upon the comparison.

7 . The method of claim 1 , further comprising:

determining a simulated surface weight (SWOB') on the drill string based upon the identified rock type;

comparing the SWOB to the SWOB' to produce a comparison; and

calibrating the rock type based upon the comparison.

8 . The method of claim 1 , further comprising displaying the friction factor, the DTOR, the DWOB, and the rock type.

9 . A computing system, comprising:

one or more processors; and

a memory system comprising one or more non-transitory computer-readable media storing instructions that, when executed by at least one of the one or more processors, cause the computing system to perform operations, the operations comprising:

capturing one or more measurements at a surface of a wellbore that extends into a subterranean formation, wherein the one or more measurements comprise a surface torque (STOR) on a drill string that extends into the wellbore and a surface weight (SWOB) on the drill string;

determining a friction factor based upon the STOR when a drill bit is off-bottom in the wellbore, wherein the drill bit is coupled to a lower end of the drill string;

determining a downhole torque on the drill bit (DTOR) and a downhole weight on the drill bit (DWOB) when the drill bit is on-bottom in the wellbore, wherein the DTOR and the DWOB are determined based upon the STOR, the SWOB, and the friction factor;

identifying a rock type in the subterranean formation based at least partially upon the friction factor, the DTOR, and the DWOB;

simulating the drill bit drilling on-bottom through a plurality of different rock types in a model to produce a plurality of simulated torques on the drill bit (BTORs) and a plurality of simulated weights on the drill bit (BWOBs), wherein the plurality of different rock types include the identified rock type;

comparing the DTOR to the BTORs to produce a first comparison;

comparing the DWOB to the BWOBs to produce a second comparison, wherein the rock type is identified based upon the first comparison and the second comparison; and

performing a wellsite action based upon the rock type, wherein the wellsite action comprises generating or transmitting a signal that adjusts the STOR, the SWOB on the drill string, a number of rotations per minute (RPM) of the drill string, a rate of penetration (ROP) of the drill string, or a combination thereof.

10 . The computing system of claim 9 , wherein the operations further comprise:

determining a simulated surface torque (STOR') on the drill string and a simulated surface weight (SWOB') on the drill string based upon the identified rock type;

calibrating the friction factor to produce a calibrated friction factor based at least partially upon the STOR'; and

calibrating the rock type to produce a calibrated rock type based at least partially upon the SWOB'.

11 . The computing system of claim 10 , wherein the operations further comprise:

comparing the STOR to the STOR' to produce a first comparison;

comparing the SWOB to the SWOB' to produce a second comparison;

calibrating the friction factor to produce the calibrated friction factor based upon the first comparison and the second comparison; and

calibrating the rock type to produce the calibrated rock type based upon the first comparison and the second comparison.

12 . The computing system of claim 9 , wherein the operations further comprise displaying the friction factor, the DTOR, the DWOB, and the rock type.

13 . A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a computing system, cause the computing system to perform operations, the operations comprising:

capturing one or more measurements at a surface of a wellbore that extends into a subterranean formation, wherein the one or more measurements comprise a surface torque (STOR) on a drill string that extends into the wellbore, a number of rotations per minute (RPM) of the drill string, a rate of penetration (ROP) of the drill string, and a surface weight (SWOB) on the drill string;

determining a friction factor based upon the STOR when a drill bit is off-bottom in the wellbore, wherein the drill bit is coupled to a lower end of the drill string;

determining a downhole torque on the drill bit (DTOR) and a downhole weight on the drill bit (DWOB) when the drill bit is on-bottom in the wellbore, wherein the DTOR and the DWOB are determined based upon the STOR, the SWOB, and the friction factor;

simulating the drill bit drilling on-bottom through a plurality of different rock types in a model to produce a plurality of simulated torques on the drill bit (BTORs) and a plurality of simulated weights on the drill bit (BWOBs);

comparing the DTOR to the BTORs produce a first comparison;

comparing the DWOB to the BWOBs to produce a second comparison;

identifying one of the rock types based upon the first comparison and the second comparison, wherein the identified rock type has a smallest difference between the DTOR and the BTORs, the DWOB and the BWOBs, or both;

determining a simulated surface torque (STOR') on the drill string and a simulated surface weight (SWOB') on the drill string based upon the identified rock type;

comparing the STOR to the STOR' to produce a third comparison;

comparing the SWOB to the SWOB' to produce a fourth comparison;

calibrating the friction factor to produce a calibrated friction factor based upon the third comparison and the fourth comparison;

calibrating the rock type to produce a calibrated rock type based upon the third comparison and the fourth comparison; and

performing a wellsite action based upon the calibrated friction factor and the calibrated rock type, wherein the wellsite action comprises generating or transmitting a signal that adjusts the number of RPM, the STOR, the SWOB, the ROP, or a combination thereof.