Certain aspects and features relate to a system that includes a drilling tool, a processor, and a non-transitory memory device that includes instructions that are executable by the processor to cause the processor to perform operations. The operations include receiving input data that corresponds to characteristics of at least one of drilling fluid, a drillstring, or a wellbore. The operations also include calculating at least one dynamic sideforce and at least one dynamic, hydraulic force based at least in part on the input data. The operations also include determining an equilibrium solution for an output value using the at least one dynamic sideforce and at least one dynamic, hydraulic force. The operations also include applying the output value to the drilling tool for controlling operation of the drilling tool.

Certain aspects and features relate to a system that includes a drilling tool, a processor, and a non-transitory memory device that includes instructions that are executable by the processor to cause the processor to perform operations. The operations include receiving input data that corresponds to characteristics of at least one of drilling fluid, a drillstring, or a wellbore. The operations also include calculating at least one dynamic sideforce and at least one dynamic, hydraulic force based at least in part on the input data. The operations also include determining an equilibrium solution for an output value using the at least one dynamic sideforce and at least one dynamic, hydraulic force. The operations also include applying the output value to the drilling tool for controlling operation of the drilling tool.

A method of controlling a horizontal directional drill having a rotary drive system. The rotary drive system includes a variable displacement pump providing pressurized fluid to a motor, a displacement control that adjusts motor displacement, a torque limiter valve that opens at a torque limit to provide pressurized fluid to the displacement control to allow the system to limit torque, and cross-port relief valves that open at a cross-port relief pressure to limit pressure applied across a motor inlet and a motor outlet. The method includes adjusting the torque limiter pressure to vary the maximum torque applied to a drill string based on operating parameters of the horizontal direction drill, and adjusting the cross-port relief pressure to be higher than the torque limiter pressure each time that the torque limiter pressure is adjusted.

A downhole ratchet is utilized between tubulars in the drill string to reduce torsion energy in the drill string. The downhole ratchet is constructed to release when the tubular below the ratchet spins faster than the tubular above the ratchet. When the tubular below spins more slowly or at the same speed then the ratchet mechanism locks the upper and lower tubulars together to rotate the bit. The effect is to release torsional energy in the drill string to reduce and eliminate slip stick oscillations.

A downhole ratchet is utilized between tubulars in the drill string to reduce torsion energy in the drill string. The downhole ratchet is constructed to release when the tubular below the ratchet spins faster than the tubular above the ratchet. When the tubular below spins more slowly or at the same speed then the ratchet mechanism locks the upper and lower tubulars together to rotate the bit. The effect is to release torsional energy in the drill string to reduce and eliminate slip stick oscillations.

An automated slide drilling system (ASDS) may be used with a drilling rig system to control slide drilling. The ASDS may autonomously control slide drilling without user input during the slide drilling. The ASDS may further support a transition from rotary drilling to slide drilling to rotary drilling without user input during the transitions. The ASDS may also support user input and user notifications for various steps to enable manual or semi-manual control of slide drilling by a driller or an operator.

An automated slide drilling system (ASDS) may be used with a drilling rig system to control slide drilling. The ASDS may autonomously control slide drilling without user input during the slide drilling. The ASDS may further support a transition from rotary drilling to slide drilling to rotary drilling without user input during the transitions. The ASDS may also support user input and user notifications for various steps to enable manual or semi-manual control of slide drilling by a driller or an operator.

Systems and methods for regulating weight-on-bit (WOB). Systems and methods for regulating WOB may monitor and change the rate of penetration (ROP) or may maintain the ROP within a target range therefor. The methods for regulating WOB may include characterizing an average force profile, determining whether force profile disturbances occur at similar well elevator position, receiving data stream of hook load and elevator positions, and applying a force correction to the hook load during tool joint passing events. Systems and methods for regulating WOB may receive force profile data and sensor measurements including WOB, torque, and differential pressure for a current position of the tool joint and provide an adjustment to the ROP or maintain an ROP when the tooljoint passes through the rotating head.

Systems and methods for regulating weight-on-bit (WOB). Systems and methods for regulating WOB may monitor and change the rate of penetration (ROP) or may maintain the ROP within a target range therefor. The methods for regulating WOB may include characterizing an average force profile, determining whether force profile disturbances occur at similar well elevator position, receiving data stream of hook load and elevator positions, and applying a force correction to the hook load during tool joint passing events. Systems and methods for regulating WOB may receive force profile data and sensor measurements including WOB, torque, and differential pressure for a current position of the tool joint and provide an adjustment to the ROP or maintain an ROP when the tooljoint passes through the rotating head.

Methods and apparatus for including obtaining raw surface data for present values of torque (T.sub.TD) generated by a top drive operably coupled with a drillstring, obtaining raw surface data for present values of rotational speed (ω) of the top drive corresponding to the T.sub.TD, obtaining inertia (J.sub.TD) of the top drive, and estimating torque T.sub.ST of the drillstring based on the obtained T.sub.TD data, the obtained data, and the obtained J.sub.TD data. The estimated drillstring torque T.sub.ST may be utilized to determine a surface torque oscillation performance index (STOPI).