Methods, systems and media for controlling a toolface of a downhole tool

1. A method of controlling a toolface of a downhole tool, comprising:

when a drill bit is off-bottom relative to a wellbore:

determining, based on a differential pressure, a total amount of reactive rotation to be introduced to a drill string connected to the drill bit, wherein determining the total amount of reactive rotation comprises:

determining an off-bottom amount of rotation, wherein the off-bottom amount of rotation is an amount of reactive rotation to be introduced to the drill string before a touchdown condition has been met; and

determining an on-bottom amount of rotation, wherein the on-bottom amount of rotation is an amount of reactive rotation to be introduced to the drill string after the touchdown condition has been met; and

performing a first toolface control operation comprising rotating the drill string by the off-bottom amount of rotation;

measuring the differential pressure;

determining, based on the measured differential pressure exceeding a threshold, that the touchdown condition has been met; and

in response to determining that the touchdown condition has been met, performing a second toolface control operation comprising further rotating the drill string by the on-bottom amount of rotation so as to counteract a reactive torque acting on the toolface, wherein the total amount of reactive rotation is equal to a sum of the off-bottom and on-bottom amounts of rotation.

2. The method of claim 1 , wherein rotating the drill string comprises adjusting a rotary drive unit position setpoint corresponding to a desired position of a rotary drive unit operable to rotate the drill string.

3. The method of claim 2 , wherein the rotary drive unit position setpoint comprises a top drive position setpoint, and wherein the rotary drive unit comprises a top drive.

4. The method of claim 1 , wherein determining, based on the differential pressure, the total amount of reactive rotation comprises:

determining a difference between a differential pressure setpoint and an initial differential pressure; and

determining the total amount of rotation based on the determined difference.

5. The method of claim 1 , wherein the off-bottom amount of rotation is at least as large as the on-bottom amount of rotation.

6. The method of claim 1 , further comprising, before performing the first toolface control operation, rotating the drill string by an initial amount of rotation.

7. The method of claim 6 , further comprising:

before performing the first toolface control operation,

determining an initial toolface of the downhole tool; and

determining a toolface setpoint, wherein the initial toolface and the toolface setpoint define an expected toolface range; and

further rotating the drill string if the toolface of the downhole tool is determined to be outside of the expected toolface range.

8. The method of claim 1 , wherein performing the second toolface control operation comprises further rotating the drill string by the on-bottom amount proportionally to increasing differential pressure.

9. The method of claim 1 , further comprising:

after performing the second toolface control operation, determining that a depth of the drill bit corresponds to a depth of the wellbore; and

in response to determining that the depth of the drill bit corresponds to the depth of the wellbore, performing a third toolface control operation comprising further rotating the drill string.

10. The method of claim 9 , wherein performing the third toolface control operation comprises:

increasing a differential pressure setpoint such that the differential pressure setpoint corresponds to a reactive pressure; and

further rotating the drill string based on the increased differential pressure setpoint.

11. The method of claim 1 , further comprising, after performing the second toolface control operation:

determining a toolface error based on a difference between the toolface of the downhole tool and a toolface setpoint;

adjusting, based on the toolface error, one or more drilling parameter setpoints; and

inputting the one or more adjusted drilling parameter setpoints to one or more drilling controllers for controlling the toolface of the downhole tool.

12. The method of claim 11 , wherein adjusting the one or more drilling parameter setpoints comprises:

selecting, based on the toolface error, the one or more drilling parameter setpoints from among multiple drilling parameter setpoints; and

adjusting the selected one or more drilling parameter setpoints.

13. A computer-readable medium having stored thereon computer program code configured, when executed by one or more processors, to cause the one or more processors to perform a method of controlling a toolface of a downhole tool, comprising:

when a drill bit is off-bottom relative to a wellbore:

determining, based on a differential pressure, a total amount of reactive rotation to be introduced to a drill string connected to the drill bit, wherein determining the total amount of reactive rotation comprises:

determining an off-bottom amount of rotation, wherein the off-bottom amount of rotation is an amount of reactive rotation to be introduced to the drill string before a touchdown condition has been met; and

determining an on-bottom amount of rotation, wherein the on-bottom amount of rotation is an amount of reactive rotation to be introduced to the drill string after the touchdown condition has been met; and

performing a first toolface control operation comprising rotating the drill string by the off-bottom amount of rotation;

measuring the differential pressure;

determining, based on the measured differential pressure exceeding a threshold, that the touchdown condition has been met; and

in response to determining that the touchdown condition has been met, performing a second toolface control operation comprising further rotating the drill string by the on-bottom amount of rotation so as to counteract a reactive torque acting on the toolface, wherein the total amount of reactive rotation is equal to a sum of the off-bottom and on-bottom amounts of rotation.