Abstract: A method for offshore dual-drive core drilling with three layers of casings under surge compensation is provided. According to the method, a drilling vessel is located at set latitude and longitude coordinates by a dynamic positioning system; drill pipes are stabilized by a seabed template; torques and drilling pressures can be transmitted during drilling of the casings by means of surge compensation of the casings at a wellhead; during drilling for sampling, the surge compensation can compensate to a certain extent for a change in water depth caused by rising or falling tides, or surge, thereby preventing the casings from colliding with equipment and ensuring the safety of wellhead operation; and the drilling of three layers of casings is achieved by means of dual driver heads to effectively protect a wellbore wall, such that high core-drilling rate and good core-drilling quality are achieved during drilling for sampling.

Abstract: A method for offshore dual-drive core drilling with three layers of casings under surge compensation is provided. According to the method, a drilling vessel is located at set latitude and longitude coordinates by a dynamic positioning system; drill pipes are stabilized by a seabed template; torques and drilling pressures can be transmitted during drilling of the casings by means of surge compensation of the casings at a wellhead; during drilling for sampling, the surge compensation can compensate to a certain extent for a change in water depth caused by rising or falling tides, or surge, thereby preventing the casings from colliding with equipment and ensuring the safety of wellhead operation; and the drilling of three layers of casings is achieved by means of dual driver heads to effectively protect a wellbore wall, such that high core-drilling rate and good core-drilling quality are achieved during drilling for sampling.

Abstract: The present invention belongs to the technical field of marine exploration, and discloses a forward physical simulation method for seismic response characteristics of a marine natural gas hydrate system. A physical model is established according to distribution characteristics of a hydrate system in a research area; seismic response characteristics of natural gas hydrates and underlying free gas are determined; and a seismic interpretation result of the natural gas hydrate system is corrected according to a forward physical simulation result, so that forward physical simulation of the marine natural gas hydrate system is realized.

Abstract: The present invention relates to a reagent for exploiting natural gas hydrates, which includes a regent A and a regent B. The reagent A is PEG400-polyurethane prepolymer; the reagent B includes PEG400 and an initiator; and a volume ratio of the PEG400-polyurethane prepolymer, the PEG400 and the initiator is (1-3000):(1-1000):(1-2000). The reagent of the present invention has excellent performance and high stability, and can effectively “replace” the “water” of the natural gas hydrate; and moreover, the reaction is exothermic reaction to effectively increase the reaction rate, which reduces the energy loss on the one hand, and reduces the blockage of a gas passage caused by the secondary generation of the natural gas hydrates in a low-temperature high-pressure pipeline during transferring on the other hand.

Abstract: An application method of a device for accurately evaluating the vertical content distribution of an undersea hydrate reservoir includes the following steps: assembling the device into a whole and screwing it into an undersea well; activating natural gas hydrates to produce gaseous substances; opening a directional guide channel corresponding to a thermal excitation system in a working state in S2, so that gaseous natural gas hydrates generated in this horizon enter a screw-in long sleeve through the directional guide channel; collecting, by a gas collection system, the gaseous natural gas hydrates; analyzing and recording components and contents in a box by an optical ranging unit and a resistivity unit; repeating S4 and S5 till the end of one collection cycle; and performing data processing and analysis. In this way, accurate evaluation of the vertical content distribution of undersea hydrates is realized.

Abstract: An application method of a device for accurately evaluating the vertical content distribution of an undersea hydrate reservoir includes the following steps: assembling the device into a whole and screwing it into an undersea well; activating natural gas hydrates to produce gaseous substances; opening a directional guide channel corresponding to a thermal excitation system in a working state in S2, so that gaseous natural gas hydrates generated in this horizon enter a screw-in long sleeve through the directional guide channel; collecting, by a gas collection system, the gaseous natural gas hydrates; analyzing and recording components and contents in a box by an optical ranging unit and a resistivity unit; repeating S4 and S5 till the end of one collection cycle; and performing data processing and analysis. In this way, accurate evaluation of the vertical content distribution of undersea hydrates is realized.

Abstract: A system for stereoscopic and real-time monitoring of an ocean methane profile includes a waterborne communication floating body, a gravity anchor, and a monitoring mechanism disposed therebetween, wherein the monitoring mechanism includes a submarine methane leakage intensity monitoring apparatus, a plurality of methane monitoring apparatus capable of synchronously monitoring methane content and a hydrodynamic environment, and a plastic-coated steel cable connected between the waterborne communication floating body and the gravity anchor; a data acquisition cabin is connected to the plastic-coated steel cable through a first communication module; and a first floating ball assembly is connected to the plastic-coated steel cable through a fixing rope. The submarine methane leakage intensity monitoring apparatus and the plurality of methane monitoring apparatus are disposed between the gravity anchor and the waterborne communication floating body at predetermined intervals.

Abstract: The present application discloses a device and method for detecting and ablating hydrates in a natural gas pipeline. The device includes a transmission mechanism, a detection mechanism and an ablation mechanism. The detection mechanism and the ablation mechanism are both connected to the transmission mechanism through an elastic connector, such that the device can smoothly pass through bends in the natural gas pipeline. The transmission mechanism includes a universal wheel component, which forms static friction with an outer wall of an inner natural gas pipeline, such that the device can move along the inner natural gas pipeline. The detection mechanism detects the temperature of the natural gas pipeline and determines whether hydrates are generated in the natural gas pipeline to block the pipeline, and then the blockage is heated by the ablation mechanism to ablate the hydrates.

Abstract: The present application discloses a long-term, in-situ sampling and analysis device for sediment pore water and a method thereof. The long-term in-situ sampling and analysis device for sediment pore water includes a bracket, a probe, an elevator, a diverting device, a first water storage device, and a second water storage device, a peristaltic pump, a dissolved gas of sediment pore water analysis device and an in-situ environment measurement device. The present application can collect and store the sediment pore water in an in-situ, long-term and time-phased manner, and in low measuring error level.

Abstract: The present invention discloses a natural gas hydrate-bearing sediment intergranular micro-force testing device and a testing method thereof. The testing device comprises: a high pressure reactor, a natural gas cylinder, a natural gas buffer tank, a condensate circulation device, a water source and a gas-liquid saturated tank, wherein a gas inlet of the natural gas buffer tank communicates with the natural gas cylinder through a first pipeline, a gas outlet of the natural gas buffer tank communicates with a gas inlet of the high pressure reactor through a second pipeline, a water inlet of the high pressure reactor communicates with a water outlet of the gas-liquid saturated tank through a third pipeline, a water inlet of the gas-liquid saturated tank communicates with the water source through a fourth pipeline, the gas outlet of the natural gas buffer tank communicates with the fourth pipeline through a fifth pipeline.

Abstract: 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.

Abstract: 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.