A natural gas hydrate pressure-retaining corer includes an outer tube assembly and an inner tube assembly installed inside the outer tube assembly. The inner tube assembly includes a first inner tube assembly and a second inner tube assembly. The first inner tube assembly includes a spearhead, a latching device, a suspension plug, a hydraulic piston tube, a piston short limit short section, a limit copper pin, a sealing head, a middle tube, a weight tube drive mechanism and a pressure-retaining ball valve closing sealing mechanism which are sequentially connected from top to bottom. The second inner tube assembly includes a piston compensation balance mechanism, a single-action mechanism, an accumulator mechanism, a sealing mechanism and a core barrel connected sequentially from top to bottom.

A natural gas hydrate pressure-retaining corer includes an outer tube assembly and an inner tube assembly installed inside the outer tube assembly. The inner tube assembly includes a first inner tube assembly and a second inner tube assembly. The first inner tube assembly includes a spearhead, a latching device, a suspension plug, a hydraulic piston tube, a piston short limit short section, a limit copper pin, a sealing head, a middle tube, a weight tube drive mechanism and a pressure-retaining ball valve closing sealing mechanism which are sequentially connected from top to bottom. The second inner tube assembly includes a piston compensation balance mechanism, a single-action mechanism, an accumulator mechanism, a sealing mechanism and a core barrel connected sequentially from top to bottom.

Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

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.

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.

A method for preparing an artificial core includes steps of: (1) preparing materials: dividing quartz sand of different particle sizes into multiple groups, adding a cementing agent into all the groups, and thoroughly stirring to obtain quartz sand mixtures with different permeabilities; (2) assembling a mold: assembling the mold into a cuboid with a hollow sand-filling groove inside; (3) wetting the mold: spraying water onto a bottom surface of the sand-filling groove with a fine water nozzle to wet the mold; (4) filling with sand: placing separators in the mold to divide the sand-filling groove into multiple parts corresponding to a group quantity of the quartz sand; sequentially pouring the quartz sand mixtures into the mold in an order from large to small particle sizes; then removing the separators, and flattening a surface of the quartz sand mixtures; (5) compacting; and (6) firing for molding and de-moulding.

A method for preparing an artificial core includes steps of: (1) preparing materials: dividing quartz sand of different particle sizes into multiple groups, adding a cementing agent into all the groups, and thoroughly stirring to obtain quartz sand mixtures with different permeabilities; (2) assembling a mold: assembling the mold into a cuboid with a hollow sand-filling groove inside; (3) wetting the mold: spraying water onto a bottom surface of the sand-filling groove with a fine water nozzle to wet the mold; (4) filling with sand: placing separators in the mold to divide the sand-filling groove into multiple parts corresponding to a group quantity of the quartz sand; sequentially pouring the quartz sand mixtures into the mold in an order from large to small particle sizes; then removing the separators, and flattening a surface of the quartz sand mixtures; (5) compacting; and (6) firing for molding and de-moulding.

Apparatus and method for in-situ stabilization of unconsolidated sediment in core samples are disclosed. The core sampling apparatus includes a corer having an inner wall, an outer wall, and a plurality of impregnation tubes disposed between the inner and the outer wall, wherein the impregnation tubes are parallel to a central axis of the corer. The method for sampling a core includes extracting a core sample using a corer, and in-situ stabilizing unconsolidated sediment in the core sample within the corer by impregnating the core sample with a resin. The resin is supplied through a plurality of impregnation tubes disposed between the walls of the corer.

Apparatus and method for in-situ stabilization of unconsolidated sediment in core samples are disclosed. The core sampling apparatus includes a corer having an inner wall, an outer wall, and a plurality of impregnation tubes disposed between the inner and the outer wall, wherein the impregnation tubes are parallel to a central axis of the corer. The method for sampling a core includes extracting a core sample using a corer, and in-situ stabilizing unconsolidated sediment in the core sample within the corer by impregnating the core sample with a resin. The resin is supplied through a plurality of impregnation tubes disposed between the walls of the corer.