System and method for determining a transfer of torque from the surface to a drill bit

Abstract

A method for determining a total torque output at a drill bit includes receiving an on-bottom pressure and an off-bottom pressure. The method also includes determining a differential pressure based upon the on-bottom pressure and the off-bottom pressure. The method also includes receiving a surface torque. The method also includes determining a torque transmission coefficient based at least partially upon the differential pressure and the surface torque. The method also includes determining the total torque output at the drill bit based at least partially upon the differential pressure, the surface torque, and the torque transmission coefficient.

What is claimed is: 
     
         1 . A method for determining a total torque output at a drill bit, the method comprising:
 receiving an on-bottom pressure and an off-bottom pressure;   determining a differential pressure based upon the on-bottom pressure and the off-bottom pressure;   receiving a surface torque;   determining a torque transmission coefficient based at least partially upon the differential pressure and the surface torque; and   determining the total torque output at the drill bit based at least partially upon the differential pressure, the surface torque, and the torque transmission coefficient.   
     
     
         2 . The method of  claim 1 , wherein the on-bottom pressure and the off-bottom pressure are measured by a pressure sensor at a surface above a wellbore, wherein the on-bottom pressure comprises a pressure when a bottom hole assembly (BHA) is on a bottom of the wellbore, and wherein the off-bottom pressure comprises the pressure when the BHA is off of the bottom of the wellbore. 
     
     
         3 . The method of  claim 1 , wherein the surface torque is measured by a torque sensor, wherein the torque sensor is coupled to a top drive, wherein the surface torque comprises a torque introduced to a drill string by the top drive, wherein the drill string extends into a wellbore, wherein a bottom hole assembly (BHA) is coupled to a lower end of the drill string, and wherein the BHA comprises a mud motor and the drill bit. 
     
     
         4 . The method of  claim 1 , wherein the torque transmission coefficient is a positive unitless coefficient that is less than 1 and represents a torque transmission between stator rubber and a rotor in a mud motor. 
     
     
         5 . The method of  claim 1 , wherein determining the torque transmission coefficient comprises:
 receiving a torque below a mud motor;   multiplying a torque slope of the mud motor and the differential pressure to produce a first value;   subtracting the first value from the torque below the mud motor to produce a second value; and   dividing the second value by the surface torque to produce the torque transmission coefficient.   
     
     
         6 . The method of  claim 1 , wherein the torque transmission coefficient is also determined based at least partially upon a temperature in a wellbore, a pressure in the wellbore, a rate of rotation of a drill string in the wellbore, a weight on the drill bit in the wellbore, and a flow rate of a fluid pumped into the wellbore. 
     
     
         7 . The method of  claim 1 , wherein determining the total torque output comprises:
 multiplying a torque slope of a mud motor and the differential pressure to produce a first value;   multiplying the surface torque and the torque transmission coefficient to produce a second value; and   adding the first value and the second value to produce the total torque output.   
     
     
         8 . The method of  claim 1 , further comprising displaying the total torque output. 
     
     
         9 . The method of  claim 1 , further comprising performing a wellsite action in response to the total torque output. 
     
     
         10 . The method of  claim 9 , wherein the wellsite action comprises varying the on-bottom pressure, varying the off-bottom pressure, varying an amount of torque introduced into a drill string, varying a rate of rotation of the drill string, varying a weight on the drill bit, varying a toolface setting of a bottom hole assembly (BHA), varying a flow rate of a fluid being pumped into a wellbore, or a combination thereof. 
     
     
         11 . A computing system, comprising:
 at least one processor; and   a storage medium connected to the at least one processor, the storage medium including instructions for configuring the computing system to perform operations comprising:
 receiving an on-bottom pressure and an off-bottom pressure that are measured by a pressure sensor, wherein the pressure sensor is at a surface above a wellbore, wherein the on-bottom pressure comprises a pressure when a bottom hole assembly (BHA) is on a bottom of the wellbore, and wherein the off-bottom pressure comprises the pressure when the BHA is off of the bottom of the wellbore; 
 determining a differential pressure comprising a difference between the on-bottom pressure and the off-bottom pressure; 
 receiving a surface torque measured by a torque sensor, wherein the surface torque comprises a torque introduced to a drill string by a top drive, wherein the torque sensor is coupled to the top drive, wherein the drill string extends into the wellbore, wherein the BHA is coupled to a lower end of the drill string, and wherein the BHA comprises a mud motor and a drill bit; 
 determining a torque transmission coefficient based at least partially upon the differential pressure and the surface torque, wherein the torque transmission coefficient is a positive unitless coefficient that is less than 1 and represents a torque between a rotor and stator rubber in the mud motor; and 
 determining a total torque output at the drill bit based at least partially upon the differential pressure, the surface torque, and the torque transmission coefficient. 
   
     
     
         12 . The computing system of  claim 11 , wherein the operations further comprise determining that performance of the mud motor is degrading in response to the total torque output deviating from an expected torque output by more than a predetermined torque threshold. 
     
     
         13 . The computing system of  claim 11 , wherein the operations further comprise determining that the drill string is sliding in the wellbore in response to the total torque output being less than a predetermined torque threshold. 
     
     
         14 . The computing system of  claim 11 , wherein the operations further comprise determining that the drill string is rotating in the wellbore in response to the total torque output being greater than a predetermined torque threshold. 
     
     
         15 . The computing system of  claim 11 , wherein determining the total torque output comprises:
 multiplying a torque slope of the mud motor and the differential pressure to produce a first value;   multiplying the surface torque and the torque transmission coefficient to produce a second value; and   adding the first value and the second value to produce the total torque output.   
     
     
         16 . A non-transitory machine-readable storage medium having instructions stored thereon to configure a processor of a computing system to perform operations, the operations comprise:
 receiving an on-bottom pressure and an off-bottom pressure that are measured by a pressure sensor, wherein the pressure sensor is at a surface above a wellbore, wherein the on-bottom pressure comprises a pressure when a bottom hole assembly (BHA) is on a bottom of the wellbore, and wherein the off-bottom pressure comprises the pressure when the BHA is off of the bottom of the wellbore;   determining a differential pressure comprising a difference between the on-bottom pressure and the off-bottom pressure;   receiving a surface torque measured by a torque sensor, wherein the surface torque comprises a torque introduced to a drill string by a top drive, wherein the torque sensor is coupled to the top drive, wherein the drill string extends into the wellbore, wherein the BHA is coupled to a lower end of the drill string, and wherein the BHA comprises a mud motor and a drill bit;   determining a torque transmission coefficient based at least partially upon the differential pressure and the surface torque, wherein the torque transmission coefficient is a positive unitless coefficient that is less than 1 and represents a torque between a rotor and stator rubber in the mud motor;   determining a total torque output at the drill bit based at least partially upon the differential pressure, the surface torque, and the torque transmission coefficient, wherein the total torque output is determined by a model, and wherein determining the total torque output comprises:
 multiplying a torque slope of the mud motor and the differential pressure to produce a first value; 
 multiplying the surface torque and the torque transmission coefficient to produce a second value; and 
 adding the first value and the second value to produce the total torque output; and 
   generating a signal in response to the total torque output, wherein the signal causes one or more parameters to vary, and wherein the one or more parameters comprise the on-bottom pressure, the off-bottom pressure, an amount of the torque introduced into the drill string by the top drive, a weight on the drill bit, a rate of rotation of the drill string, the BHA, or both, a toolface setting of the BHA, a flow rate of a fluid being pumped into the wellbore, or a combination thereof.   
     
     
         17 . The non-transitory machine-readable storage medium of  claim 16 , wherein determining the torque transmission coefficient comprises:
 receiving a torque below the mud motor;   multiplying the torque slope of the mud motor and the differential pressure to produce a third value;   subtracting the third value from the torque below the mud motor to produce a fourth value; and   dividing the fourth value by the surface torque to produce the torque transmission coefficient.   
     
     
         18 . The non-transitory machine-readable storage medium of  claim 16 , wherein the torque transmission coefficient is determined also based at least partially upon a temperature in the wellbore, a pressure in the wellbore, a rate of rotation of the drill string or the BHA in the wellbore, a weight on the drill bit in the wellbore, and the flow rate of the fluid pumped into the wellbore, and wherein the torque transmission coefficient is determined using artificial intelligence (AI), machine-learning (ML), or both. 
     
     
         19 . The non-transitory machine-readable storage medium of  claim 16 , wherein the operations further comprise determining that the BHA has encountered an abnormal pressure event at least partially in response to the torque transmission coefficient, the total torque output, or both, and wherein determining that the BHA has encountered the abnormal pressure event comprises:
 measuring a first standpipe pressure (SPP) at the surface;   determining a second SPP at the surface; and   determining that the first SPP differs from the second SPP by more than a predetermined pressure.   
     
     
         20 . The non-transitory machine-readable storage medium of  claim 19 , wherein determining the second SPP comprises:
 multiplying a first constant and the flow rate squared to produce a first SPP value;   multiplying a second constant, the flow rate squared, and a depth of the drill bit to produce a second SPP value;   multiplying a third constant and the total torque output to produce a third SPP value;   multiplying a fourth constant and the weight on the drill bit to produce a fourth SPP value; and   adding the first SPP value, the second SPP value, the third SPP value, the fourth SPP value, and a fifth constant to produce the second SPP, wherein the first, second, third, fourth, and fifth constants are different.