Disclosed is a drilling system for rock drilling with a drill string, wherein the drill string includes at least one bendable drill pipe. The drilling system further includes at least two block and tackle systems for driving an end of the drill string in a first direction; and at least two conveyor devices adapted to guide and bend the drill string between the first direction and a second direction, so as to convert a motion of the drill string between the first direction and the second direction.

A method for mitigating the effects of cable wear in an active heave compensated hoisting system of an offshore vessel in a locked to bottom mode of operation is disclosed. The method comprises supporting an upper end of a string which is connected to a subsea well from a travelling block of the hoisting system, wherein the travelling block is suspended from a crown block via a cable. The method further comprises operating an active heave compensation system to control a drawworks of the hoisting system to pay in and out the cable to compensate for motion of the offshore vessel and maintain a target overpull in the string. The method further comprises adjusting a ballast system of the offshore vessel to vary the draft of the vessel, and controlling the drawworks in accordance with the variation in the draft of the vessel to cause a length of cable to slip through the hoisting system and maintain the target overpull in the string.

A method for mitigating the effects of cable wear in an active heave compensated hoisting system of an offshore vessel in a locked to bottom mode of operation is disclosed. The method comprises supporting an upper end of a string which is connected to a subsea well from a travelling block of the hoisting system, wherein the travelling block is suspended from a crown block via a cable. The method further comprises operating an active heave compensation system to control a drawworks of the hoisting system to pay in and out the cable to compensate for motion of the offshore vessel and maintain a target overpull in the string. The method further comprises adjusting a ballast system of the offshore vessel to vary the draft of the vessel, and controlling the drawworks in accordance with the variation in the draft of the vessel to cause a length of cable to slip through the hoisting system and maintain the target overpull in the string.

A passive heave compensator, including an elastic cable, an electromagnetic damping device, a cylindrical sector, and a disc damping plate. The electromagnetic damping device includes a first cylinder including a helical coil, a permanent magnet mechanism disposed in the first cylinder, a first cover plate, a second cover plate, a first sliding shaft, a second sliding shaft, a first spring, a second spring, a first end cover, and a second end cover. The cylindrical sector includes a roof plate, a middle plate, a base plate, a first side plate, a second side plate, and a curved plate. The disc damping plate is disposed around the middle plate of cylindrical sector. The elastic cable is directly connected to the electromagnetic damping device. The electromagnetic damping device is disposed in the central part of the cylindrical sector. The middle plate is disposed between the roof plate and the base plate.

The present invention is a method and a system for the energy management of an energy storage of an electrical system. The electrical system comprises at least one element (EMO) which moves under the action of swell, a means for driving the mobile means, and an energy storage. The energy storage means includes at least one supercapacitor. According to the invention, the energy management of the supercapacitor is controlled by determining ageing of the at least one supercapacitor beforehand used an ageing model of the at least one supercapacitor and a prediction of its future demand based on an estimate of future swell (HOU). The invention also relates to a wave energy system and a heave compensator having such an energy management system.

The present invention is a method and a system for the energy management of an energy storage of an electrical system. The electrical system comprises at least one element (EMO) which moves under the action of swell, a means for driving the mobile means, and an energy storage. The energy storage means includes at least one supercapacitor. According to the invention, the energy management of the supercapacitor is controlled by determining ageing of the at least one supercapacitor beforehand used an ageing model of the at least one supercapacitor and a prediction of its future demand based on an estimate of future swell (HOU). The invention also relates to a wave energy system and a heave compensator having such an energy management system.

A motion compensating system and method for use on a vessel during well intervention operations through a riser. The system can comprise an upper floor having an opening therethrough, a lower base having an opening therethrough positioned below the upper floor, a first plurality of cylinders extending between the upper floor and lower base, and a riser tensioner. Each cylinder of the plurality of cylinders can be pivotally connected to the upper floor and lower base for moving the upper floor with respect to the lower base. The riser tensioner can have an upper portion, lower portion, and central cavity extending longitudinally through the upper and lower portions, wherein the upper portion can be adapted for connection with a riser or an intermediate tubular member that is connectable to the riser. The lower portion can be connected to the lower base within or about the opening of the lower base.

A motion compensating system and method for use on a vessel during well intervention operations through a riser. The system can comprise an upper floor having an opening therethrough, a lower base having an opening therethrough positioned below the upper floor, a first plurality of cylinders extending between the upper floor and lower base, and a riser tensioner. Each cylinder of the plurality of cylinders can be pivotally connected to the upper floor and lower base for moving the upper floor with respect to the lower base. The riser tensioner can have an upper portion, lower portion, and central cavity extending longitudinally through the upper and lower portions, wherein the upper portion can be adapted for connection with a riser or an intermediate tubular member that is connectable to the riser. The lower portion can be connected to the lower base within or about the opening of the lower base.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.