Digital underreamer

Abstract

Wellbore drilling apparatus and methods are provided. The apparatus includes a reaming subassembly including one or more reamers configured to ream a wellbore. The reaming subassembly defines a cutting aggressiveness that is variable while the reaming subassembly is disposed in a wellbore. The apparatus also includes an actuator coupled with the reaming subassembly and configured to vary the cutting aggressiveness of the reaming subassembly in response to an actuation signal.

What is claimed is: 
     
         1 . A wellbore drilling apparatus, comprising:
 a reaming subassembly comprising one or more reamers configured to ream a wellbore, the reaming subassembly defining a cutting aggressiveness that is variable while the reaming subassembly is disposed in a wellbore; and   an actuator coupled with the reaming subassembly and configured to vary the cutting aggressiveness of the reaming subassembly in response to an actuation signal.   
     
     
         2 . The apparatus of  claim 1 , further comprising a controller communicable with the actuator and configured to send the actuation signal to the actuator. 
     
     
         3 . The apparatus of  claim 2 , wherein the controller is located remotely from the actuator. 
     
     
         4 . The apparatus of  claim 2 , further comprising a body coupled to the reaming subassembly and comprising a proximal end coupled with a drill pipe and a distal end coupled with a drill bit. 
     
     
         5 . The apparatus of  claim 4 , wherein the controller is communicable with the actuator through a wire extending at least partially along the drill pipe. 
     
     
         6 . The apparatus of  claim 4 , wherein the controller is communicable with the actuator via a wireless signal, an acoustic signal, an electrical signal, or a combination thereof. 
     
     
         7 . The apparatus of  claim 4 , further comprising one or more sensors configured to provide data to the controller indicative of whether a mechanical load on the reaming subassembly is disproportionate to a mechanical load on the drill bit. 
     
     
         8 . The apparatus of  claim 7 , wherein the one or more sensors comprise a mechanical load sensor, a vibration sensor, a formation evaluation sensor, or a combination thereof. 
     
     
         9 . The apparatus of  claim 7 , wherein the one or more sensors are located in the body and proximal the reaming subassembly, or in the drill bit, or in the drill pipe, or a combination thereof. 
     
     
         10 . The apparatus of  claim 1 , wherein the reaming subassembly comprises:
 a first reamer having a cutting aggressiveness; and   a second reamer axially offset from the first reamer and having a greater cutting aggressiveness than the first reamer, wherein the actuator is configured to cause the first reamer to retract and the second reamer to expand, to increase the cutting aggressiveness of the reaming subassembly, and to cause the first reamer to expand and the second reamer to retract, to reduce the cutting aggressiveness of the reaming subassembly.   
     
     
         11 . The apparatus of  claim 1 , wherein the reaming subassembly comprises a cutting element pivotal over a range of back rake angles to vary the cutting aggressiveness of the reaming subassembly. 
     
     
         12 . The apparatus of  claim 1 , wherein the reaming subassembly includes a cutting element and a wear pad, the wear pad being configured to extend outward to reduce a cutting depth of the cutting element and to retract inward to increase the cutting depth of the cutting element. 
     
     
         13 . A method for reaming while drilling, comprising:
 drilling a pilot hole for a wellbore with a drill bit of a drilling assembly;   reaming the pilot hole with a reaming subassembly of the drilling assembly;   detecting, using a sensor, that a mechanical load on the reaming subassembly is disproportionate to a mechanical load on the drill bit; and   in response to detecting that the mechanical load on the reaming subassembly is disproportionate to the mechanical load on the drill bit, varying a cutting aggressiveness of the reaming subassembly while the reaming subassembly is disposed in the wellbore.   
     
     
         14 . The method of  claim 13 , wherein varying the cutting aggressiveness comprises:
 receiving, using a controller, a signal from the sensor, the signal indicating that the mechanical load on the reaming subassembly is disproportionate to the mechanical load on the drill bit;   sending an actuation signal from the controller to an actuator coupled with the reaming subassembly;   receiving the actuation signal with the actuator; and   in response to receiving the actuation signal, adjusting the reaming subassembly using the actuator.   
     
     
         15 . The method of  claim 14 , further comprising powering the actuator with a battery positioned proximal the drilling assembly. 
     
     
         16 . The method of  claim 13 , wherein varying the cutting aggressiveness of the reaming subassembly comprises:
 retracting a first reamer of the reaming subassembly, the first reamer having a first cutting aggressiveness; and   expanding a second reamer of the reaming subassembly, the second reamer having a second cutting aggressiveness that is different from the first cutting aggressiveness.   
     
     
         17 . The method of  claim 13 , wherein varying the cutting aggressiveness of the reaming subassembly comprises varying a back rake angle of a cutting element of the reaming subassembly. 
     
     
         18 . The method of  claim 13 , wherein varying the cutting aggressiveness of the reaming subassembly comprises varying a cutting depth of a cutting element of the reaming subassembly. 
     
     
         19 . The method of  claim 18 , wherein varying the cutting depth of the cutting element comprises extending or retracting a wear pad. 
     
     
         20 . A method for controlling a drilling assembly, comprising:
 determining that a mechanical load on a drill bit of the drilling assembly is disproportionate to a mechanical load on a reaming subassembly of the drilling assembly; and   in response, varying a cutting aggressiveness of the reaming subassembly while the drilling assembly remains in the wellbore.   
     
     
         21 . The method of  claim 20 , wherein varying the cutting aggressiveness of the reaming subassembly comprises:
 receiving a signal using an actuator coupled with the reaming subassembly; and   in response to receiving the signal, adjusting the reaming subassembly using the actuator.   
     
     
         22 . The method of  claim 21 , wherein adjusting the reaming subassembly using the actuator comprises modulating one or more valves fluidly coupled with the reaming subassembly. 
     
     
         23 . The method of  claim 20 , wherein determining comprises detecting axial vibration, torsional vibration, lateral vibration, one or more formation rock properties, or a combination thereof. 
     
     
         24 . The method of  claim 20 , wherein determining comprises detecting a mechanical load on the reaming subassembly, the drill bit, or both. 
     
     
         25 . The method of  claim 20 , wherein varying the cutting aggressiveness comprises expanding a first reamer of the reaming subassembly and retracting a second reamer of the reaming subassembly to alter the cutting aggressiveness of the reaming subassembly. 
     
     
         26 . The method of  claim 20 , wherein varying the cutting aggressiveness comprises adjusting a back rake angle of a reamer of the reaming subassembly. 
     
     
         27 . The method of  claim 20 , wherein varying the cutting aggressiveness comprises adjusting a cutting depth of a reamer of the reaming subassembly. 
     
     
         28 . A drilling apparatus, comprising:
 a drilling assembly comprising a body having a proximal end coupled with a drill pipe and a distal end coupled with a drill bit, and a reaming subassembly coupled to the body between the proximal end and the distal end, wherein the reaming subassembly defines a cutting aggressiveness that is variable while the drilling assembly is disposed in the wellbore;   a sensor configured to sense when a load on the drill bit is disproportionate to a load on the reaming subassembly; and   a controller communicable with the drilling assembly and the sensor, the controller configured to signal the drilling assembly to adjust the cutting aggressiveness of the reaming subassembly in response to data received from the sensor.   
     
     
         29 . The drilling apparatus of  claim 28 , further comprising an actuator coupled with the reaming subassembly such that actuation of the actuator varies the cutting aggressiveness of the reaming subassembly, wherein the controller is communicable with the actuator. 
     
     
         30 . The drilling apparatus of  claim 28 , wherein the sensor is positioned in the drill bit. 
     
     
         31 . The drilling apparatus of  claim 28 , wherein the sensor is positioned in the body of the drilling assembly. 
     
     
         32 . The drilling apparatus of  claim 31 , wherein the sensor is positioned proximal the reaming subassembly. 
     
     
         33 . The drilling apparatus of  claim 28 , wherein the sensor is positioned in the drill pipe. 
     
     
         34 . The drilling apparatus of  claim 28 , wherein the sensor is a vibration sensor. 
     
     
         35 . The drilling apparatus of  claim 28 , wherein the sensor is a mechanical load sensor. 
     
     
         36 . The drilling apparatus of  claim 28 , wherein the sensor is a formation evaluation sensor, or a logging sensor, or a combination thereof, and is configured to measure one or more rock formation properties.