An example method for removal of stick-slip vibrations may comprise receiving a command directed to a controllable element of a drilling assembly. A smooth trajectory profile may be generated based, at least in part, on the command. A frictional torque value for a drill bit of the drilling assembly may be determined. The example method may further include generating a control signal based, at least in part, on the trajectory profile, the frictional torque value, and a model of the drilling assembly, and transmitting the control signal to the controllable element.

A multi-fluid drilling system 10 drilling is disclosed for drilling a hole or well 11. The system 10 is coupled to a dual wall drill string 12. The drill string 12 is configured to enable separate flow of a first fluid 14 and a second fluid 16. The system 10 has a hammer 22 and a downhole motor 24. Both the hammer 22 and the motor 24 are supported by and are coupled to the drill string 12. The motor 24 is uphole of the hammer 22. The hammer 22 is arranged so that when supported by the drill string 12 the first fluid 14 when flowing through the drill string 12 is able to flow to and power the hammer 22. As the motor 24 is disposed between the hammer 22 and the drill string 12 the first fluid 14 is also able to flow through the motor 24. To this end the motor 24 has a channel 25 to enable the first fluid to flow from the drill sting 12 to the hammer 22. The channel 25 acts as a part of a flow path or conduit for the first fluid 14.

A multi-fluid drilling system 10 drilling is disclosed for drilling a hole or well 11. The system 10 is coupled to a dual wall drill string 12. The drill string 12 is configured to enable separate flow of a first fluid 14 and a second fluid 16. The system 10 has a hammer 22 and a downhole motor 24. Both the hammer 22 and the motor 24 are supported by and are coupled to the drill string 12. The motor 24 is uphole of the hammer 22. The hammer 22 is arranged so that when supported by the drill string 12 the first fluid 14 when flowing through the drill string 12 is able to flow to and power the hammer 22. As the motor 24 is disposed between the hammer 22 and the drill string 12 the first fluid 14 is also able to flow through the motor 24. To this end the motor 24 has a channel 25 to enable the first fluid to flow from the drill sting 12 to the hammer 22. The channel 25 acts as a part of a flow path or conduit for the first fluid 14.

A wireline system for use during drilling operations. The wireline system has a wireline assembly and a roller assembly. Both the wireline assembly and the roller assembly are positioned within a front portion of a drill rig.

A wireline system for use during drilling operations. The wireline system has a wireline assembly and a roller assembly. Both the wireline assembly and the roller assembly are positioned within a front portion of a drill rig.

In one aspect there is provided an apparatus to transmit hydraulic force to a snubbing unit's traveling slip assembly. The apparatus comprises a first hydraulic power source having a hydraulic connection to the traveling slip assembly, a hydraulic power source actuator to actuate the hydraulic power source to cause it to transmit hydraulic force to or from the traveling slip assembly. Rotation isolation means are provided to rotationally isolate the hydraulic power source actuator from the first hydraulic power source, and to transfers axial and radial loads between the hydraulic power source actuator 65 and the first hydraulic power source. The first hydraulic power source is mounted to the traveling slip assembly so as to co-rotate therewith.

In one aspect there is provided an apparatus to transmit hydraulic force to a snubbing unit's traveling slip assembly. The apparatus comprises a first hydraulic power source having a hydraulic connection to the traveling slip assembly, a hydraulic power source actuator to actuate the hydraulic power source to cause it to transmit hydraulic force to or from the traveling slip assembly. Rotation isolation means are provided to rotationally isolate the hydraulic power source actuator from the first hydraulic power source, and to transfers axial and radial loads between the hydraulic power source actuator 65 and the first hydraulic power source. The first hydraulic power source is mounted to the traveling slip assembly so as to co-rotate therewith.

A method and apparatus for drilling wells for producing petroleum products from an earth formation that is covered by shallow water having a depth of about 600 or less, using a self-elevating drilling unit (SEDU) to drill one or more wells having wellheads located at or near the seabed. Well drilling is accomplished through a blowout preventer stack and a drilling spool string having a wellhead connector secured at its lower end and establishing releasable connection with the subsea wellhead. As a plurality of wells are being drilled, production of petroleum products can begin from wells that have already been completed, thus initiating an income stream from petroleum production starting only a few months from initiation of well drilling activity. When a well has been drilled, completed and rendered safe, the drilling spool string and wellhead connector is removed to the SEDU, leaving the wellhead positioned at the seabed in readiness for later production.

A method and apparatus for drilling wells for producing petroleum products from an earth formation that is covered by shallow water having a depth of about 600 or less, using a self-elevating drilling unit (SEDU) to drill one or more wells having wellheads located at or near the seabed. Well drilling is accomplished through a blowout preventer stack and a drilling spool string having a wellhead connector secured at its lower end and establishing releasable connection with the subsea wellhead. As a plurality of wells are being drilled, production of petroleum products can begin from wells that have already been completed, thus initiating an income stream from petroleum production starting only a few months from initiation of well drilling activity. When a well has been drilled, completed and rendered safe, the drilling spool string and wellhead connector is removed to the SEDU, leaving the wellhead positioned at the seabed in readiness for later production.

A rotatable plate is configured to be coupled to a rotary table of a rig floor. The rotatable plate defines a central passage through which a tubular can be passed. Multiple arms each have a first end rotably coupled to the rotatable plate. The arms are hinged such that a distal end of the arms, away from the rotatable plate, are configured to move towards or away from the passage. Each of arms extends away from the rotatable plate towards the passage. The arms are biased away from the passage. Rollers are rotably coupled to one of the distal ends of the arms.