Slide drilling system and method

1. A method for drilling, comprising:

receiving a drilling model of a drilling system comprising:

a drilling device coupled to a surface structure;

a drill string coupled to the drilling device and extending therefrom into a wellbore, the drill string comprising a motor;

a drawworks;

a drilling line connected to the drawworks and the drilling device, such that the drawworks is configured to raise and lower the drilling device;

an actuator connected to the drilling link and the surface structure;

selecting a frequency and amplitude for an axial vibration of the drill string based on the drilling model;

and

generating the axial vibration of the drill string substantially at the frequency and the amplitude selected, wherein the axial vibration is selectively and automatically introduced at the surface structure in response to the drilling string being in sliding mode, by one or more of:

modulating a hookload; and

introducing an axial movement pattern.

2. The method of claim 1 , wherein selecting the frequency and amplitude comprises selecting a frequency and amplitude for oscillations of weight-on-bit.

3. The method of claim 1 , further comprising:

measuring a performance characteristic while generating the axial vibration;

selecting a second frequency and a second amplitude;

generating the axial vibration at the second frequency and second amplitude;

measuring the performance characteristic while generating the axial vibration at the second frequency and the second amplitude; and

determining whether to adjust the frequency, the amplitude, or both based on the performance characteristic.

4. The method of claim 1 , further comprising:

determining a first toolface orientation for the drill string before generating the axial vibration;

determining a second toolface orientation for the drill string after generating the axial vibration; and

adjusting the frequency, amplitude, or both of the axial vibration based on a difference between the first and second toolface orientations.

5. The method of claim 1 , further comprising:

calculating a hookload maximum and minimum for the drilling system based on the drilling model;

determining an envelope for the frequency and amplitude of the axial vibration based on the hookload maximum and the hookload minimum.

6. The method of claim 1 , further comprising:

determining that a bottom-hole assembly of the drill string is steering to a first direction,

wherein the axial vibration is generated in response to determining that the bottom-hole assembly of the drill string is steering to the first direction.

7. The method of claim 6 , further comprising:

determining that the bottom-hole assembly is steering to a second direction; and

in response to determining that the bottom-hole assembly is steering to the second direction, increasing the hookload.

8. A system for drilling, comprising:

a surface structure;

a drilling device coupled to the surface structure;

a drill string coupled to the drilling device and extending therefrom into a wellbore, the drill string comprising a motor;

a drawworks;

a drilling line connected to the drawworks and the drilling device, such that the drawworks is configured to raise and lower the drilling device;

an actuator connected to the drilling line and the surface structure, wherein the actuator is configured to vertically oscillate a position of the drilling device and cause axial vibration in the drill string; and

a processor coupled to the actuator,

wherein the processor is configured to select a frequency and an amplitude for axial vibration in the drill string,

wherein the processor is configured to detect the drilling string being in sliding mode,

wherein the processor automatically transmits signals to the actuator, causing the actuator to generate the axial vibration in the drill string, in response to the processor determining that the drilling string is in sliding mode.

9. The system of claim 8 , wherein selecting the frequency and amplitude comprises selecting a frequency and amplitude for oscillations of weight-on-bit.

10. The system of claim 8 , wherein the processor is further configured to perform operations comprising:

measuring a performance characteristic while generating the axial vibration;

selecting a second frequency and a second amplitude;

generating the axial vibration at the second frequency and second amplitude;

measuring the performance characteristic while generating the axial vibration at the second frequency and the second amplitude; and

determining whether to adjust the frequency, the amplitude, or both based on the performance characteristic.

11. The system of claim 8 , wherein the processor is further configured to perform operations comprising:

determining a first toolface orientation for the drill string before generating the axial vibration;

determining a second toolface orientation for the drill string after generating the axial vibration; and

adjusting the frequency, amplitude, or both of the axial vibration based on a difference between the first and second toolface orientations.

12. The system of claim 8 , wherein the processor is further configured to perform operations comprising:

calculating a hookload maximum and minimum for the drilling system based on the drilling model;

determining an envelope for the frequency and amplitude of the axial vibration based on the hookload maximum and the hookload minimum.

13. The system of claim 8 , wherein the processor is further configured to perform operations comprising:

determining that a bottom-hole assembly of the drill string is steering to a first direction,

wherein the axial vibration is generated in response to determining that the bottom-hole assembly of the drill string is steering to the first direction.

14. The system of claim 13 , wherein the processor is further configured to perform operations comprising:

determining that the bottom-hole assembly is steering to a second direction; and

in response to determining that the bottom-hole assembly is steering to the second direction, increasing the hookload.

15. A non-transitory, computer-readable medium storing instructions that, when executed by at least one processor of a computing system, causing the computing system to perform operations, the operations comprising:

receiving a drilling model of a drilling system comprising:

a drilling device coupled to a surface structure;

a drill string coupled to the drilling device and extending therefrom into a wellbore, the drill string comprising a motor;

a drawworks;

a drilling line connected to the drawworks and the drilling device, such that the drawworks is configured to raise and lower the drilling device;

an actuator connected to the drilling link and the surface structure;

selecting a frequency and amplitude for an axial vibration of the drill string based on the drilling model; and

causing the actuator to generate the axial vibration of the drill string substantially at the frequency and the amplitude selected, wherein the axial vibration is selectively and automatically introduced at the surface structure in response to the drilling string being in sliding mode, by one or more of:

modulating a hookload; and

introducing an axial movement pattern for execution by a downhole vibrator.

16. The medium of claim 15 , wherein selecting the frequency and amplitude comprises selecting a frequency and amplitude for oscillations of weight-on-bit.

17. The medium of claim 16 , wherein the operations further comprise:

measuring a performance characteristic while generating the axial vibration;

selecting a second frequency and a second amplitude;

generating the axial vibration at the second frequency and second amplitude;

measuring the performance characteristic while generating the axial vibration at the second frequency and the second amplitude; and

determining whether to adjust the frequency, the amplitude, or both based on the performance characteristic.

18. The medium of claim 15 , wherein the operations further comprise:

determining a first toolface orientation for the drill string before generating the axial vibration;

determining a second toolface orientation for the drill string after generating the axial vibration; and

adjusting the frequency, amplitude, or both of the axial vibration based on a difference between the first and second toolface orientations.

19. The medium of claim 15 , wherein the operations further comprise:

calculating a hookload maximum and minimum for the drilling system based on the drilling model;

determining an envelope for the frequency and amplitude of the axial vibration based on the hookload maximum and the hookload minimum.

20. The medium of claim 15 , wherein the operations further comprise:

determining that a bottom-hole assembly of the drill string is steering to a first direction,

wherein the axial vibration is generated in response to determining that the bottom-hole assembly of the drill string is steering to the first direction.