Abstract: A lock plug (7A) is inserted into a plug installation position of an insertion hole (5a) of a tool stem (5) connected to a drill string (10), and when a fluid has flowed to the insertion hole (5a), a stopper (62) protrudes radially outward from a tool body (6) and is locked to a subsea wellhead (4) and an internal stopper (66) protrudes radially inward from the tool body (6) and is locked to the tool stem (5) in a lock state. An unlock plug is inserted into the plug installation position of the insertion hole (5a), and when the fluid has flowed into the insertion hole (5a), the stopper (62) is separated from the subsea wellhead (4) and the internal stopper (66) is separated from the tool stem (5) to release the lock state.

Abstract: The submarine drilling support system includes a first guide support part that has a ring shape, has a plurality of rollers of which roller axes are directed to a horizontal direction and is arranged along a circumferential direction going around a rotation support axis parallel to a vertical direction, and is provided to allow the drill pipe to be inserted through in the vertical direction; and a first rotation holding part that is configured to support the first guide support part so as to be rotatable in the circumferential direction. The pluralities of rollers are adjacent to each other in the circumferential direction and are arranged in a state where the drill pipe is able to insert through a space surrounded by the plurality of rollers.

Abstract: A lock plug (7A) is inserted into a plug installation position of an insertion hole (5a) of a tool stem (5) connected to a drill string (10), and when a fluid has flowed to the insertion hole (5a), a stopper (62) protrudes radially outward from a tool body (6) and is locked to a subsea wellhead (4) and an internal stopper (66) protrudes radially inward from the tool body (6) and is locked to the tool stem (5) in a lock state. An unlock plug is inserted into the plug installation position of the insertion hole (5a), and when the fluid has flowed into the insertion hole (5a), the stopper (62) is separated from the subsea wellhead (4) and the internal stopper (66) is separated from the tool stem (5) to release the lock state.

Abstract: The submarine drilling support system includes a first guide support part that has a ring shape, has a plurality of rollers of which roller axes are directed to a horizontal direction and is arranged along a circumferential direction going around a rotation support axis parallel to a vertical direction, and is provided to allow the drill pipe to be inserted through in the vertical direction; and a first rotation holding part that is configured to support the first guide support part so as to be rotatable in the circumferential direction. The pluralities of rollers are adjacent to each other in the circumferential direction and are arranged in a state where the drill pipe is able to insert through a space surrounded by the plurality of rollers.

Abstract: A power generation system includes a hydrothermal fluid well including a drilled hole reaching down to a hydrothermal fluid reservoir present below an ocean floor from an ocean floor surface and a casing installed in the drilled hole through a guide base on the ocean floor surface, an anode provided on a flow channel for hot water formed by the hydrothermal fluid well, a cathode provided in seawater other than the flow channel for hot water formed by the hydrothermal fluid well, and an ocean floor device that is connected with the anode and the cathode respectively and extracts generated power so as to operate. Power is easily and stably supplied on the ocean floor.

Abstract: A recovery method for recovering mineral resources from a hydrothermal fluid reservoir present beneath the ocean floor includes the steps of: (A) providing a hydrothermal fluid well by drilling a hole reaching a hydrothermal fluid reservoir from an ocean floor surface via a guide base on the ocean floor surface, and then installing a casing in the drilled hole via the guide base; (B) precipitating minerals on a mineral-culturing device by installing the mineral-culturing device on the base guide so as to cover a well head of the hydrothermal fluid well, and bringing hot water ejecting from the well head into contact with sea water on the mineral-culturing device; and (C) recovering minerals precipitated on the mineral-culturing device together with the mineral-culturing device.

Abstract: The invention is a recovery method for recovering mineral resources from a hydrothermal fluid reservoir present beneath the ocean floor, the recovery method including the steps of: (A) providing a hydrothermal fluid well by drilling a hole reaching a hydrothermal fluid reservoir from an ocean floor surface via a guide base on the ocean floor surface, and then installing a casing in the drilled hole via the guide base; (B) precipitating minerals on the mineral-culturing device by installing a mineral-culturing device on the base guide so as to cover a well head of the hydrothermal fluid well, and bringing hot water ejecting from the well head into contact with sea water on the mineral-culturing device; and (C) recovering minerals precipitated on the mineral-culturing device together with the mineral-culturing device.