A daily gas production rate of a methane hydrate deposit is calculated based on inflow performance relationship formulas. Step 1 determines the production stage, including the gas production rate trend of a production test and selecting an inflow performance relationship formula corresponding to the stage. Step 2 calculates basic coefficient terms related to energy conversion in the inflow performance relationship formula. Step 3 obtains other coefficient terms related to production in the inflow performance relationship formula. Step 4 predicts the gas production rate under other production pressure differences. Staged inflow performance relationship formulas characterize the complex methane hydrate deposit production performance. Gas production rate and deposit pressure under a large pressure differences are predicted through simple production tests under a small pressure difference, providing a basis for production design of the hydrate deposit and preventing accidents that may be caused by direct production under a large pressure difference.

The disclosure discloses a method for obtaining formation parameters of a gas hydrate reservoir through well testing interpretation, which comprises: (1) establishing a physical model for well testing interpretation of the gas hydrate reservoir according to multiphase flow, hydrate dissociation, secondary hydrate formation and heat transfer exhibited in the well testing process of the gas hydrate reservoir; (2) establishing a mathematical model for well testing interpretation of the gas hydrate reservoir; (3) conducting spatial discretization and temporal discretization on the mathematical model, and adopting a finite volume method to obtain a numerical solution of bottom-hole pressure; (4) calculating a bottom-hole pressure variation curve and a production rate variation curve in the well testing process of the hydrate reservoir, and drawing theoretical curves of bottom-hole pressure difference and pressure difference derivative; and (5) matching a measured pressure curve with the theoretical curve to obtain the relevant formation parameters.

A real-time monitoring apparatus for seafloor deformation during hydrate exploitation, includes a main frame, a detecting device, and a sensing and wireless data transmitting device. The detecting device includes at least two detecting straight rods in different directions; the detecting straight rods are connected to the main frame through the movable sleeves; and at least two fixing supports are configured below each detecting straight rod, perpendicular to and uniformly distributed along the detecting straight rod. A movable lever is configured above each detecting straight rod, the movable lever is connected to the main frame through the lever-fixing rod, and a stretchable and compressible spring is configured at an upper end of the movable lever. The sensing and wireless data transmitting device includes at least two tension and compression force sensors in different directions, a gyroscope sensor, a wireless data transmitter, and a power source, all mounted in the main frame.

A natural gas hydrate solid-state fluidization mining method and system under an underbalanced positive circulation condition, used for performing solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure has an earlier-stage construction process, underbalanced hydrate solid-state fluidization mining construction process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced positive circulation method, and problems such as shaft safety, production control and environmental risks faced by conventional natural gas hydrate mining methods such as depressurization, heat injection, agent injection and replacement are effectively solved. By using the natural gas hydrate solid-state fluidization mining method weak-cementation non-rock-forming natural gas hydrates in the seafloor can be mined in environment-friendly, efficient, safe and economical modes, more energy resources are provided, and energy shortage dilemmas are solved.

A crushing system for large-size natural gas hydrate rock samples, which mainly includes a crushing and stirring control subsystem, crushing and stirring execution subsystem and hydrate preparation subsystem. Full automatic control to parameter acquisition and experimental process is achieved by utilizing modern automation technology, including the function of automatically crushing the large-size natural gas hydrate rock samples and also monitoring, collecting and storing the drilling pressure, the torque and the internal furnace pressure and temperature parameters during the crushing process in real time, to provide reliable guarantee for the follow-up researches on crushing mechanism, crushing efficiency, drilling parameter optimization, rock crushing ability evaluation of a crushing tool and the like of the large-size natural gas hydrate rock samples and necessary experimental verification means for optimization of on-site exploiting construction conditions of natural gas hydrate.

A hydrate solid-state fluidization mining method and system under an underbalanced reverse circulation condition are used for solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure includes an earlier-stage construction process, pilot hole drilling construction process, reverse circulation jet fragmentation process, underbalanced reverse circulation fragment recovery process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced reverse circulation method. Problems such as shaft safety, production control and environmental risks faced by conventional natural gas hydrate mining methods such as depressurization, heat injection, agent injection and replacement are effectively solved. By using the method, the weak-cementation non-rock-forming natural gas hydrates in the seafloor can be mined in environment-friendly, efficient, safe and economical modes, more energy resources can be provided, and energy shortage dilemmas are solved.

A submarine shallow hydrate exploitation device, including an exploitation unit and a collection unit. The exploitation unit includes: a submarine ship working on a seabed; a drain chamber arranged on the submarine ship, wherein a pressure valve is arranged at a top of the drain chamber, one-way drain holes are formed in a bottom of the drain chamber, and water from massive hydrates is controlled to be discharged out of the drain chamber; a high-speed spiral bit configured to mine and convey sediments; a rotary ring arranged at an inlet end of the drain chamber and configured to connect the drain chamber with the high-speed spiral bit to provide rotation power for the high-speed spiral bit; a steering arm arranged on the submarine ship and configured to realize a rotation of the high-speed spiral bit; a crusher arranged on the submarine ship and configured to crush dried massive hydrates.

A method for intelligently determining hydrate drilling and production risks based on fuzzy judgment. First classifying monitoring parameters in a hydrate drilling and production process into layers from top to bottom: a target layer, a primary evaluation factor layer and a secondary evaluation factor layer; then calculating relative weight values of each primary evaluation factor and each secondary evaluation factor contained therein; then connecting in series the relative weight values of the primary evaluation factors with the relative weight values of the secondary evaluation factors to obtain an overall weight value of the secondary evaluation factors; repeating the foregoing steps; finally constructing the overall weight value of each secondary evaluation factor of each risk into a column vector to obtain a comprehensive determining weight matrix of hydrate drilling and production risks, and determining the risks in the hydrate drilling and production process by combining monitoring parameter change vectors.

The present invention discloses a pressurized test device and method for in-situ mining natural gas hydrates by jets, relating to the field of exploitation of marine natural gas hydrates. The device comprises an injection system, a jet breakup system, an annular pressure system, an axial pressure system, a backpressure system, a vacuum system, a simulation system, a collecting and processing system and a metering system, all of which can operate independently by controlling pipe valves on pipelines. The loading of the confining pressure of the device is independent of the loading of the axial pressure, without interference to each other. Meanwhile, the jet breakup process of natural gas hydrate-containing sediments can be observed in real time by a video camera.

Methods of dissociating and recovering methane from solid hydrate deposits are provided. A method for recovering methane from a methane hydrate includes at least applying electromagnetic radiation to the methane hydrate to dissociate the methane-water bond. Further provided is an apparatus for dissociating methane from a methane hydrate. The apparatus includes at least: an electromagnetic spectrum power source; a probe connected to the electromagnetic spectrum power source; an antenna connected to the distal end of the probe is capable of focusing a radiated beam into a target area of a methane hydrate; and a control system in communication with and capable of controlling the electromagnetic spectrum power source, the probe, and the antenna.