A process for drilling natural gas hydrates. A drilling rig is placed in seawater. A suction-press core drilling mode is adopted in a soft sediment formation, a suction-rotary core drilling mode is adopted in a medium-hard sediment formation, or a pumping direction circle-rotary core drilling mode is adopted in a hard sediment formation. A core is extracted. An inner tube for wireline pressure coring is recovered. A holding seal cap is tightened, and the inner tube is stored in a pipe storage rack. Punching is carried out. An inner tube for wireline pressure coring which is hollow is captured to disengage the holding seal cap. The inner tube is lowered. A drill rod is added. The punching is carried out again. The above steps are repeated until the core drilling reaches a given drilling depth. The drill rod, the drill and the corer are recovered.

A process for drilling natural gas hydrates. A drilling rig is placed in seawater. A suction-press core drilling mode is adopted in a soft sediment formation, a suction-rotary core drilling mode is adopted in a medium-hard sediment formation, or a pumping direction circle-rotary core drilling mode is adopted in a hard sediment formation. A core is extracted. An inner tube for wireline pressure coring is recovered. A holding seal cap is tightened, and the inner tube is stored in a pipe storage rack. Punching is carried out. An inner tube for wireline pressure coring which is hollow is captured to disengage the holding seal cap. The inner tube is lowered. A drill rod is added. The punching is carried out again. The above steps are repeated until the core drilling reaches a given drilling depth. The drill rod, the drill and the corer are recovered.

The present invention relates to a natural gas hydrate rotary pressure-retaining corer, including an outer tube assembly and an inner tube assembly installed inside the outer tube assembly. The inner tube assembly includes an inner tube assembly a and an inner tube assembly b. The inner tube assembly a includes a spearhead, a latch mechanism, a long tube, a middle tube sub, a short joint, a sealing sub, a connecting tube, a middle tube and a pressure-retaining ball valve closing sealing mechanism connected sequentially from top to bottom. The inner tube assembly b includes a lifting device, a latch suspension mechanism, an spirol pin sub, a single-action mechanism, a dapter, an adjustment joint, a connecting tube, a sealing mechanism, a connecting long tube, a connecting long tube sub and a core barrel connected sequentially from top to bottom.

Disclosed is a process for drilling natural gas hydrates with a submersible core drilling rig using pressure wireline, including: 1) placing the drilling rig in seawater; 2) adopting a suction-press core drilling mode in a soft sediment formation, a suction-rotary core drilling mode in a medium-hard sediment formation, or a pumping direct circle-rotary core drilling mode in a hard sediment formation; 3) extracting a core; 4) recovering an inner tube for wireline pressure coring; 5) tightening a holding seal cap and storing the inner tube in a pipe storage rack; 6) punching; 7) capturing an inner tube for wireline pressure coring which is hollow and disengaging the holding seal cap; 8) lowering the inner tube; 9) adding a drill rod; 10) punching; 11) repeating steps (210) till the core drilling reaches a given drilling depth; 12) recovering the drill rod and the drill; 13) recovering the corer.

Disclosed is a process for drilling natural gas hydrates with a submersible core drilling rig using pressure wireline, including: 1) placing the drilling rig in seawater; 2) adopting a suction-press core drilling mode in a soft sediment formation, a suction-rotary core drilling mode in a medium-hard sediment formation, or a pumping direct circle-rotary core drilling mode in a hard sediment formation; 3) extracting a core; 4) recovering an inner tube for wireline pressure coring; 5) tightening a holding seal cap and storing the inner tube in a pipe storage rack; 6) punching; 7) capturing an inner tube for wireline pressure coring which is hollow and disengaging the holding seal cap; 8) lowering the inner tube; 9) adding a drill rod; 10) punching; 11) repeating steps (210) till the core drilling reaches a given drilling depth; 12) recovering the drill rod and the drill; 13) recovering the corer.

Disclosed is a sediment core-drilling process for a submarine wire-line coring drill rig, including 1) lowering the drill rig; 2) drilling in a pressure-suction mode; 3) drilling in a rotation-pressure-suction mode; 4) cutting sediment cores; 5) recovering a core inner tube; 6) cleaning bottom of hole; 7) punching before adding a drill pipe; 8) lowering another core inner tube; 9) adding the drill pipe; 10) punching after adding the drill pipe; 11) repeating the steps 2)-10) until a given hole depth is reached; 12) recovering the drill pipe and a wire-line coring outer tube drilling tool; 13) recovering the submarine wire-line coring drill rig. The core-drilling process provided herein is suited to working conditions without mud lubrication and mud protection for hole wall. This invention has advantages of low disturbance and high efficiency in coring and is suitable for remote operation.

Disclosed is a sediment core-drilling process for a submarine wire-line coring drill rig, including 1) lowering the drill rig; 2) drilling in a pressure-suction mode; 3) drilling in a rotation-pressure-suction mode; 4) cutting sediment cores; 5) recovering a core inner tube; 6) cleaning bottom of hole; 7) punching before adding a drill pipe; 8) lowering another core inner tube; 9) adding the drill pipe; 10) punching after adding the drill pipe; 11) repeating the steps 2)-10) until a given hole depth is reached; 12) recovering the drill pipe and a wire-line coring outer tube drilling tool; 13) recovering the submarine wire-line coring drill rig. The core-drilling process provided herein is suited to working conditions without mud lubrication and mud protection for hole wall. This invention has advantages of low disturbance and high efficiency in coring and is suitable for remote operation.

The present disclosure provides an automatic push corer system including a base, a power group, a Geneva transmission group, an intermittent transmission group, a vertical coring transmission group, a clamp group and a coring group. The power group is used to drive the Geneva transmission group. The Geneva transmission group is configured to perform a first intermittent rotary motion. The intermittent transmission group is configured to perform a second intermittent rotary motion. The vertical coring transmission group is configured to cooperate with the second intermittent rotary motion to perform a third intermittent rotary motion. The clamp group is configured to cooperate with the third intermittent rotary motion to perform a lifting reciprocation. The coring group is configured to cooperate with the first intermittent rotary motion and the lifting reciprocation to respectively complete a coring operation and a tubing replacing operation. Therefore, the automatic push corer system may use a single power source to complete positioning and coring operations on the marine sediment.

The present disclosure provides an automatic push corer system including a base, a power group, a Geneva transmission group, an intermittent transmission group, a vertical coring transmission group, a clamp group and a coring group. The power group is used to drive the Geneva transmission group. The Geneva transmission group is configured to perform a first intermittent rotary motion. The intermittent transmission group is configured to perform a second intermittent rotary motion. The vertical coring transmission group is configured to cooperate with the second intermittent rotary motion to perform a third intermittent rotary motion. The clamp group is configured to cooperate with the third intermittent rotary motion to perform a lifting reciprocation. The coring group is configured to cooperate with the first intermittent rotary motion and the lifting reciprocation to respectively complete a coring operation and a tubing replacing operation. Therefore, the automatic push corer system may use a single power source to complete positioning and coring operations on the marine sediment.

Disclosed herein is a device and method for correlating core sample zones with an actual subterranean depth. The disclosed device has a pair of independent distance measuring devices operably in communication with a core sample apparatus where a first distance measuring device measures the length of a core sample entering a core sampling tube and a second distance measuring device measures a drive depth of the core sampling tube entering into the ground. A processing unit is provided for correlating the two distances so as to allow a determination as to the actual depth below ground from where a given zone of the core sample is extracted.