A deepwater subsea coiled tubing drilling rig includes a lifting rack having an upper rack and a lower rack which are sleeved with each other and connected by a lifting device. A working space is enclosed by the upper rack and the lower rack, and an underwater connecting and disconnecting tool is installed in the working space; the working space is transformed between a high-position large-space state for connecting and disconnecting through the tool and a low-position small-space state for the drilling process, along with the up-down movement of the upper rack. The upper rack is provided with an underwater coiled tubing system used for lowering and lifting a downhole tool combination, and the lower rack is provided with a wellhead device.

A method and system for downhole operations that includes an energetic material with a reduced sensitivity to temperature, and a temperature rating that is higher than other energetic materials. Downhole tools that use energetic material thus can have a higher temperature rating with the reduced sensitivity energetic material. One embodiment of the energetic material includes an energetic heterocycle compound, such as 2,6-diamino-3,5-dinitropyrazine-1-oxide.

Apparatus and methods for performing subsea drilling operations. An example method may include receiving drilling fluid from a drilling fluid source at a first pressure by a pressure exchanger located within a subsea environment and receiving seawater from the subsea environment at a second pressure by the pressure exchanger to increase pressure of the drilling fluid within the pressure exchanger to a third pressure. The second and third pressures are substantially greater than the first pressure. The method may further include discharging the drilling fluid from the pressure exchanger into piping to communicate the drilling fluid to a drill forming a wellbore in a seabed and discharging the seawater from the pressure exchanger into the subsea environment.

Apparatus and methods for performing subsea drilling operations. An example method may include receiving drilling fluid from a drilling fluid source at a first pressure by a pressure exchanger located within a subsea environment and receiving seawater from the subsea environment at a second pressure by the pressure exchanger to increase pressure of the drilling fluid within the pressure exchanger to a third pressure. The second and third pressures are substantially greater than the first pressure. The method may further include discharging the drilling fluid from the pressure exchanger into piping to communicate the drilling fluid to a drill forming a wellbore in a seabed and discharging the seawater from the pressure exchanger into the subsea environment.

A system for operation on a subsea well, the system comprising at least one storage unit configured to store tubulars; a subsea mast unit comprising at least two string handling devices configured to handle a tubular string of a plurality of connected tubulars, wherein at least one of the string handling devices is configured to move vertically relative to the other of the string handling devices, and is configured to add a vertical downforce to the tubular string; and at least one handling arrangement for moving tubulars between the at least one storage unit and one of the string handling devices simultaneously with handling of the tubular string by at least one of the string handling devices. A method of lowering a tubular string into a subsea well is also provided.

A system for operation on a subsea well, the system comprising at least one storage unit configured to store tubulars; a subsea mast unit comprising at least two string handling devices configured to handle a tubular string of a plurality of connected tubulars, wherein at least one of the string handling devices is configured to move vertically relative to the other of the string handling devices, and is configured to add a vertical downforce to the tubular string; and at least one handling arrangement for moving tubulars between the at least one storage unit and one of the string handling devices simultaneously with handling of the tubular string by at least one of the string handling devices. A method of lowering a tubular string into a subsea well is also provided.

The present invention discloses a drilling system and method of a submarine drilling rig, relating to the technical field of drilling equipment. The system includes a barge, an umbilical cable, a submarine device and a drilling device; where the barge is loaded with a pneumatic-electric-hydraulic control device and a mud treatment device which are respectively connected to the submarine device through the umbilical cable; and the submarine device includes a submarine traveling device, a coiled tubing roller, a derrick, a centralized valve seat, a drill bit replacement device, a wellhead device and a casing rack. The centralized valve seat is connected to the umbilical cable for shunting mud, cement and electrical signals conveyed by the umbilical cable. The derrick is installed above the wellhead device, respectively matched with the drill bit replacement device and the casing rack for replacing drill bits and conveying and withdrawing casings. The drilling device is connected to the coiled tubing for performing drilling operations. The present invention has the advantages of low cost, high drilling and production efficiency and high safety.

The present invention discloses a drilling system and method of a submarine drilling rig, relating to the technical field of drilling equipment. The system includes a barge, an umbilical cable, a submarine device and a drilling device; where the barge is loaded with a pneumatic-electric-hydraulic control device and a mud treatment device which are respectively connected to the submarine device through the umbilical cable; and the submarine device includes a submarine traveling device, a coiled tubing roller, a derrick, a centralized valve seat, a drill bit replacement device, a wellhead device and a casing rack. The centralized valve seat is connected to the umbilical cable for shunting mud, cement and electrical signals conveyed by the umbilical cable. The derrick is installed above the wellhead device, respectively matched with the drill bit replacement device and the casing rack for replacing drill bits and conveying and withdrawing casings. The drilling device is connected to the coiled tubing for performing drilling operations. The present invention has the advantages of low cost, high drilling and production efficiency and high safety.

A method of forming a wellbore includes providing a drilling assembly comprising one or more lengths of casing and an axially retracting assembly having a first tubular; a second tubular at least partially disposed in the first tubular and axially fixed thereto; and a support member disposed in the second tubular and movable from a first axial position to a second axial position relative to the second tubular, wherein, in the first axial position, the support member maintains the second tubular axially fixed to the first tubular, and in the second axial position, allows the second tubular to move relative to the first tubular; and an earth removal member disposed below the axially retracting assembly. The method also includes rotating the earth removal member to form the wellbore; moving the support member to the second axial position; and reducing a length of the axially retracting assembly.

A method of forming a wellbore includes providing a drilling assembly comprising one or more lengths of casing and an axially retracting assembly having a first tubular; a second tubular at least partially disposed in the first tubular and axially fixed thereto; and a support member disposed in the second tubular and movable from a first axial position to a second axial position relative to the second tubular, wherein, in the first axial position, the support member maintains the second tubular axially fixed to the first tubular, and in the second axial position, allows the second tubular to move relative to the first tubular; and an earth removal member disposed below the axially retracting assembly. The method also includes rotating the earth removal member to form the wellbore; moving the support member to the second axial position; and reducing a length of the axially retracting assembly.