40 results about "Hydrate decomposition" patented technology

A method for determining a safe density window of a hydrate formation considering a mud cake under an action of drilling fluids is provided. The method establishes a heat-fluid-solid-chemical multi-field coupling model considering the seepage effect of the mud cake at the well wall and the influence of natural gas hydrate decomposition. The simulation results show the distribution of pore pressure, temperature, and solute concentration in the drilling fluid around the well after the drilling fluid invades. Based on the determination of multi-field coupling model, the determination results, combined with a Cullen-Moore criterion, and manner for calculating a safe density window of a hydrate formation considering the mud cake under the action of the drilling fluid is further established.

This invention relates to a highly efficient co-production system and method for deep-water shallow gas and natural gas hydrates, belonging to the field of deep-water oil and gas and natural gas hydrate development. It employs a one-injection-four-production well network, deploying one central well and four surrounding production wells in the target reservoir area. The central well is initially used for fracturing and fracture creation and participates in production; later, based on production decline or reservoir temperature reduction, it is converted from production to injection, used to inject anhydrous self-generating heat materials into the artificial fracture network. The four surrounding production wells are respectively deployed in the natural gas hydrate reservoir and the shallow gas reservoir, used for depressurization production in the target reservoir, achieving the co-production of shallow gas and hydrate decomposition gas. This invention solves problems existing in the development of deep-water shallow gas and natural gas hydrates, such as low reservoir permeability, difficult gas migration, significant reservoir temperature drop in the later stages of simple depressurization production, rapid gas production decline, easy secondary formation of natural gas hydrates, and difficulty in the co-production and efficient extraction of shallow gas and hydrates.

The present application relates to hydrate depressurization production numerical simulation technical field, specifically relates to hydrate decomposition method and system considering pressure wave time lag and pore structure entropy, the method includes the following steps: calculating pore structure entropy, constructing saturation and structure entropy dependent time memory kernel, combining decomposition rate threshold, pressure drop threshold, forming the decomposition front indicator function with prediction-correction mechanism;The time memory kernel, space-time inseparable causal kernel and threshold response function are subjected to space-time convolution operation, based on the decomposition front indicator function, an integral form of non-local memory hydrate decomposition rate model is established;The Peacley number is calculated by grid Darcy velocity, the scalar characteristic memory time is extended to the second-order symmetric anisotropic memory time tensor, the second-order tensor type memory variable is constructed and the evolution equation is established, the non-local memory hydrate decomposition rate model is coupled to the energy conservation equation and two-phase Darcy seepage pressure equation, and the decomposition result is obtained by iterative solution.

A hydrate decomposition inhibiting composition, a coupling enhanced solid hydrate, and a method for improving the solid hydrate storage and transportation stability relating to the technical field of natural gas safety storage and transportation are provided. The hydrate decomposition inhibiting composition contains a carboxymethyl starch salt and an alkyl glycoside surfactant. The composition improves the interface stability of the hydrate phase boundary and the mechanical stability of the hydrate and enhance the strength of the hydrate crystal interface since the colloidal solution formed by dispersing the sodium carboxymethyl starch and the alkyl glycoside surfactant in water can coat the surface of the hydrate to form a protective layer, thereby improving the structural stability of the hydrate. Therefore, the composition inhibits the decomposition of the hydrate, reduces the decomposition rate of the hydrate, and can further reduce the decomposition amount of the hydrate.

The present application belongs to the technical field of hydrate exploitation and CO2 storage, and discloses a continuous and synchronous method for hydrate exploitation and CO2 storage based on pressure distribution, which measures the related basic parameters of a reservoir, determines the phase equilibrium pressure of natural gas hydrate and CO2 hydrate in the hydrate reservoir, determines the exploitation scheme of the hydrate reservoir, determines the formation method of the CO2 cap layer, determines the dynamic change of the gas phase permeability in the hydrate decomposition reservoir, couples the related parameters such as effective stress and hydrate saturation, combines the control equation, determines the position of the pressure decomposition front in the hydrate reservoir, compares the position of the CO2 cap layer, optimizes and adjusts the position of the cap layer, determines the decomposition degree of the hydrate decomposition reservoir, and completes the high-density storage of CO2 in the abandoned natural gas reservoir. The present application realizes the continuous and synchronous operation of hydrate exploitation and CO2 storage, and greatly improves the efficiency of hydrate exploitation and CO2 storage.

The invention relates to the technical field of petroleum engineering drilling safety, and discloses a drilling well wall stability prediction method considering a hydrate reservoir creep effect, and the method comprises the following steps: S1, building hydrate reservoir initial heat flow field distribution based on TOUGH + HYDRATE software; s2, establishing an initial mechanical field of the hydrate reservoir by adopting FLAC3D software; s3, the TOUGH + HYDRATE software and the FLAC3D software are subjected to data interface coupling, and a multi-field coupling model is constructed; s4, carrying out a triaxial creep test, obtaining a strain-time curve, carrying out fitting analysis, preferably selecting a creep constitutive model, and carrying out parameter calibration; s5, fitting by utilizing origin software to obtain a function model of the creep parameters changing along with the saturation degree of the hydrate; and S6, well periphery parameter monitoring is conducted in the drilling simulation process. The method is suitable for borehole wall instability risk analysis under the synergistic effect of hydrate decomposition and reservoir creep.

The present application relates to the field of gas separation, in particular to a method for separating gas mixture by using hydrate. The method for separating gas mixture by using hydrate comprises the following steps: loading a specific ice medium into a reactor, controlling the loading amount and the length-diameter ratio of the pipeline in the reactor, then charging the reactor with gas under certain temperature conditions, opening a back pressure valve to discharge gas when the pressure in the reactor reaches the required pressure for separation and hydrate begins to form, controlling the specific exhaust rate to slowly discharge gas, stopping the charging and opening the back pressure valve to accelerate the discharge when the highest temperature in the reactor is reached, closing the back pressure valve and opening another exhaust valve to make the hydrate decompose and release gas when the pressure in the reactor reaches normal pressure, thereby completing the gas separation. The method can improve the separation efficiency of the gas mixture and reduce energy consumption.

The present application belongs to the technical field of natural gas hydrate exploitation, and discloses a device and method for real-time nondestructive calculation of equivalent specific heat in hydrate decomposition process. The device comprises a visual flat reaction kettle, a nondestructive high-precision phase state identification system, a gas and liquid inlet and exhaust system, and a computer acquisition system. The principle of the present application is that: through the method of providing uniform heat source by heat conduction outside the reaction kettle, hydrate decomposition is promoted, and internal heat convection can be ignored. Real-time volume fraction of each component is obtained by the nondestructive high-precision phase state identification system, Newton interpolation calculation is used for the volume fraction, latent heat of phase transition of hydrate deposit at adjacent temperature is calculated, and equivalent specific heat of hydrate deposit is obtained. The present application realizes real-time nondestructive calculation of equivalent specific heat field in hydrate decomposition process. The method is environmentally friendly and economical, and the device is clear and visual, which provides technical support for the research on latent heat of phase transition and equivalent specific heat in the process of hydrate exploitation.

The application relates to a hydrate decomposition microcosmic gas-liquid migration identification test system, which comprises a lamellar hydrate preparation module, a collection module and a quantitative analysis module. The lamellar hydrate preparation module comprises a transparent experimental soil tank, a lamellar hydrate sample arranged on the transparent experimental soil tank and a transparent soil tank cover plate covered on the lamellar hydrate sample. The lamellar hydrate sample is in the shape of a round cake, and an annular water permeable stone is arranged on the outer side of the lamellar hydrate sample. The collection module collects images and parameters of the lamellar hydrate sample in the process of gas-liquid migration in real time, inputs the images and parameters into the quantitative analysis module for processing, and obtains effective seepage porosity of the lamellar hydrate sample. Compared with the prior art, the application can solve the problems of real-time observation difficulty, low key information extraction efficiency and quantitative analysis difficulty of microcosmic gas-liquid migration in the hydrate decomposition process.

The invention discloses a drilling fluid invasion depth determination method and device considering hydrate decomposition. According to the technical scheme, a bidirectional feedback mechanism of hydrate decomposition and drilling fluid invasion is established, and the hydrate saturation, porosity, permeability and drilling fluid concentration of each reservoir position in each time step are dynamically calculated; the target drilling fluid concentration field on the hydrate reservoir prediction area is determined until the current time step is the preset invasion time, so that the drilling fluid invasion depth is determined according to the target drilling fluid concentration field and the preset concentration threshold value, the defect that a traditional model ignores reservoir physical property dynamic change is overcome, and the prediction accuracy is improved. And the accuracy and the reliability of the drilling fluid invasion depth are improved.

This invention relates to the field of natural gas hydrate extraction technology, specifically to a method and system for analyzing near-wellbore reservoir stress state during depressurization extraction of hydrate reservoirs. The method includes: constructing a reservoir heterogeneity index field and a spatiotemporal evolution mode; constructing a cementation weakening coefficient field by combining the spatiotemporal evolution mode and hydrate decomposition kinetic data; determining a constitutive model correction factor based on the cementation weakening coefficient field and reservoir core mechanics test data; solving for the disturbance stress amplification coefficient field; determining the equivalent stiffness of the wellbore-reservoir interface using wellbore structure data and dynamic pressure data; extracting a multi-field coupled response characteristic parameter set using the reservoir heterogeneity index field, spatiotemporal evolution mode, and equivalent stiffness of the wellbore-reservoir interface; identifying core mechanical control features by combining the cementation weakening coefficient field and the constitutive model correction factor; and completing stress state analysis based on the disturbance stress amplification coefficient field, the multi-field coupled response characteristic parameter set, and the core mechanical control features.

The application discloses a kind of natural gas hydrate core decomposition and transport property prediction method, comprising: constructing core geometric model and carrying out grid division;Chemical kinetics model and transport multiphase percolation model of natural gas hydrate decomposition are constructed;Decomposition chemical kinetics model and transport multiphase percolation model are compiled respectively using C language, and embedded in Fluent software in the form of mass and energy source term;The initial distribution of natural gas hydrate, water, gas three phases in core is inverted, and the initial distribution law of natural gas hydrate is obtained;Based on the initial distribution law of natural gas hydrate, the decomposition and transport property of natural gas hydrate core under different exploitation conditions is predicted using Fluent software.The prediction method fills the blank of existing core natural gas hydrate core decomposition and transport prediction method.

The invention relates to a hydrate granulation purification system and method for removing radionuclides in nuclear wastewater. The system comprises a feeding subsystem, a granulation system and a detection subsystem, the granulation system is provided with a hydration reactor, the feeding subsystem and the granulation system are coupled at the hydration reactor, and the detection subsystem is arranged below the hydration reactor. The feeding subsystem is used for conveying gas raw materials and nuclear wastewater to the hydration reactor through a first gas pipeline and a first liquid pipeline respectively; the granulation system controls the temperature through a first refrigeration pipeline and outputs hydrate granules through a drain valve and a discharge pipeline; the detection subsystem is used for pushing the granules into a hydrate decomposition container for decomposition to obtain decomposed water, and an ion concentration tester is used for detecting the ion concentration so as to characterize the removal effect. The system realizes integrated operation of feeding, granulation and decomposition detection, has functions of fresh water recovery and nuclide removal, has high stability and is convenient for engineering amplification.

The application relates to a natural gas hydrate decomposition process full-coupling numerical simulation method and device, wherein the method comprises the following steps: establishing a mass conservation model, an energy conservation model, a mechanical equilibrium model and a hydrate decomposition model of soil particles, hydrates, gas and water of natural gas hydrates in a decomposition process, constructing a heat-flow-force-chemistry full-coupling model of natural gas hydrates in the decomposition process, taking gas pressure, water pressure, temperature and displacement in different directions as basic unknown quantities of the model, and establishing a finite element weak integral form of the heat-flow-force-chemistry full-coupling model; performing numerical solution on the finite element weak integral form, and assembling a DEHydrate simulator based on a solution result to simulate an evolution trend of reservoir mechanical behavior of natural gas hydrates in the decomposition process. Therefore, the problems that existing hydrate decomposition simulators cannot realize complete coupling among seepage, hydrate phase change, heat transfer and geomechanics are solved.

The application relates to a method for predicting hydrate decomposition rate in a water-in-oil emulsion system. By measuring parameters such as temperature and pressure in the hydrate decomposition stage and bringing them into formula (1) to formula (3), the hydrate decomposition rate in the water-in-oil emulsion system can be effectively predicted. The method has important significance for the research and industrial popularization and application of hydrate solid storage, hydrate solid storage natural gas technology, refrigeration, chemical separation and hydrate freezing blockage risk control in oil and gas pipeline.

The present application relates to natural gas safe storage and transportation technical field, specifically relates to a kind of hydrate promoting composition and its application and gas storage and transportation method.The composition contains neutralizing agent and hydrate formation promoter;Wherein, the neutralizing agent contains component A;The component A is selected from one or more than two of methylcyclohexane, methyl tert-butyl ether, oxidized cyclopentene and tetrahydrofuran-3-ketone.The hydrate promoting composition can still improve the generation rate of hydrate, gas storage capacity and recovery rate in hydrate decomposition recovery stage under the adverse conditions that alcohol and / or salt exist in water source.

The invention provides a discrete element-based simulation method, device and medium for mechanical degradation of hydrate-containing sediment induced by hydrate decomposition, and the simulation method comprises the following steps: carrying out numerical triaxial or biaxial compression test on a hydrate-containing sediment sample, and calibrating mesoscopic parameters associated with a related contact model by combining a trial-and-error method; constructing a mechanical degradation model of the hydrate-containing sediment in the hydrate decomposition process based on discrete elements; in the mechanical degradation model, part of hydrate particles are randomly removed according to a set hydrate decomposition rate to simulate hydrate phase volume reduction, and hydrate cementation damage caused by decomposition is simulated by reducing a parallel cementation radius multiplier. The hydrate phase volume reduction and cementation damage effect are comprehensively considered in the hydrate decomposition process, the mechanical degradation behavior of the hydrate-containing sediment is accurately represented, and the method can be suitable for analyzing the mechanical characteristics of the hydrate-containing sediment with coexisting multiple occurrence forms and can be used for evaluating geological disasters and engineering risks in the hydrate exploitation process.

The invention discloses a method for cyclically preparing a gas hydrate on a large scale. The method comprises the following steps: S1, filling a reaction kettle with a water absorbing material; s2, filling water into the reaction kettle until the water absorbing material absorbs the water until the water absorbing material is saturated, and discharging free water through a liquid outlet in the bottom of the reaction kettle; s3, adjusting the temperature in the reaction kettle to a set temperature, and introducing gas into the reaction kettle to a set pressure, so that the gas hydrate grows in the pores and on the surface of the water absorbing material; s4, after the gas hydrate is generated, the gas hydrate is decomposed, and decomposed water is reserved in the water absorbing material; and repeating the step S3 to realize circular scale growth of the gas hydrate. The method disclosed by the invention is simple in operation process, water circulation is reduced to the greatest extent, and energy consumption of hydration reaction and large-scale preparation is greatly reduced; and the water absorbing material can be recycled, so that the cost is saved, the environmental pollution is avoided, and the method is suitable for industrial application of the hydrate technology.

The present application relates to air purification technical field, disclose a kind of hydrate method air purification device and method, including electromagnetic field component, filter screen, Laval nozzle and reaction component;The filter screen is arranged between electromagnetic field component and Laval nozzle, and the filter screen is installed in the end of Laval nozzle;The reaction component is communicated and is arranged in the air outlet end of Laval nozzle.The present application is accelerated by Laval nozzle, and the gas that is passed in is cooled, and get rid of the energy consumption of traditional refrigeration equipment and the problem of slow cooling speed, energy saving, while accelerating the generation of CO2 hydrate;Different particle size pollutants are purified by electromagnetic field, filter screen, water droplet and water mist attached on filter screen, and the purification effect is good;Hydrate method and Laval nozzle are added in purification method, two major elements, provide new idea for air purification;Pure CO2 and water are obtained after decomposition, and the pure CO2 of CO2 hydrate decomposition can be transported to sprinkler for recycling.

The application discloses a hydrate decomposition gas production calculation method, S1: obtaining natural gas hydrate corresponding parameters, and defining natural gas area, hydrate area and moving decomposition front; S2: establishing hydrate decomposition kinetics equation; S3: establishing hydrate decomposition material balance relationship, calculating decomposition gas volume and decomposition gas production rate; S4: obtaining expression of moving decomposition front position changing with time; S5: establishing radial seepage and pressure distribution model in natural gas area and determining natural gas area pressure distribution expression; S6: calculating natural gas hydrate decomposition gas production. Through coupling of hydrate decomposition kinetics, moving decomposition front propulsion and natural gas area radial seepage process, the gas production corresponding to hydrate decomposition is directly calculated; meanwhile, the relationship among decomposition front position, pressure distribution and gas production is described by means of analytic derivation, and the hydrate decomposition gas production can be rapidly predicted under different production systems and reservoir conditions.

The application belongs to the field of deepwater oil and gas cementing, and particularly relates to a hydrate decomposition inhibitor for cementing cement and preparation and application thereof. The hydrate decomposition inhibitor for cementing cement is polymerized from four monomers of vinyl caprolactam, 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and acrylamide. The hydrate decomposition inhibitor for cementing cement can be added in cement slurry to delay hydrate decomposition, and has little influence on the thickening performance and mechanical properties of the cement slurry. The application has important guiding significance for the safety of cementing in hydrate formations.

The present application relates to the technical field of natural gas hydrate exploitation, and particularly relates to a method and system for analyzing stress state of near-well reservoir in hydrate reservoir depressurization exploitation. The method comprises: constructing a reservoir heterogeneity index field and a space-time evolution mode, combining the space-time evolution mode and hydrate decomposition kinetics data to construct a cementation weakening coefficient field, and determining a constitutive model correction factor according to the cementation weakening coefficient field and reservoir core mechanical test data; solving a perturbation stress amplification coefficient field, determining wellbore-reservoir interface equivalent stiffness through wellbore structure data and dynamic pressure data; extracting a multi-field coupling response characteristic parameter set by using the reservoir heterogeneity index field, the space-time evolution mode and the wellbore-reservoir interface equivalent stiffness, identifying core mechanical control characteristics in combination with the cementation weakening coefficient field and the constitutive model correction factor; and completing stress state analysis according to the perturbation stress amplification coefficient field, the multi-field coupling response characteristic parameter set and the core mechanical control characteristics.

The utility model discloses a natural gas hydrate reservoir productivity measuring system, and belongs to the field of exploration reservoir sampling analysis. The device comprises a hydrate decomposition reaction kettle, a gas-liquid separator, a liquid storage tank, a gas storage tank, a data measurement system and a data acquisition and control system, the method comprises the following steps: firstly decomposing a natural gas hydrate sample, then carrying out gas-liquid separation on a decomposed product, respectively collecting gas and liquid obtained by separation, and directly measuring the total amount of liquid and gas generated in the hydrate decomposition process by combining experimental data in the system collected in real time by a data collection and control system; compared with an indirect method for surveying the saturation and productivity of the hydrate, the in-situ decomposition-based direct measurement method is created, so that the in-situ decomposition-based hydrate saturation and productivity measurement device has the advantages of simplicity in operation and data processing, accuracy in measurement result and the like, and the in-situ decomposition method is adopted for analyzing the saturation of the hydrate; and the method is of great significance to improvement of hydrate reservoir reserve assessment accuracy.

The invention discloses a cement paste system for deepwater hydrate layer well cementation and a preparation method thereof, and belongs to the technical field of oil exploitation well cementation. The cement slurry system for well cementation of the deepwater hydrate layer comprises the following components in parts by weight: 59-77 wt.% of G-grade oil well cement and 2 wt.% of micro silicon; 10 to 15 wt.% of a low hydration heat cementing material; 3 to 5 wt.% of a density reducing material; 1-3 wt.% of a suspension stabilizing material; 5-10 wt.% of a heat conduction enhanced phase change temperature control material; 1-3 wt.% of an early strength agent; 0.5 to 1 wt.% of a dispersant; and 0.5-2 wt.% of a fluid loss agent. According to the cement paste system, the key technical problems in deepwater hydrate layer well cementation are successfully solved by effectively controlling hydration heat and temperature distribution, hydrate decomposition can be prevented to the maximum extent in the well cementation process, and shaft integrity and construction safety are guaranteed.

The application discloses a kind of simulation production gas well wellbore hydrate radio frequency deblocking experimental device and method, including radio frequency transmitting system, gas injection system, liquid injection system, simulation wellbore deblocking system, data monitoring and processing system.The application can realize simulation gas well production working condition, by changing frequency current monitoring hydrate decomposition situation of jamming position, further obtain hydrate jamming block decomposition duration and gas-liquid flow under different radio frequency current, calculate the decomposition rate of wellbore hydrate, evaluate the deblocking effect of radio frequency heating under different gas-liquid ratio conditions.Simulation deblocking effect is good, and operability is strong.

The application discloses a natural gas hydrate core productivity real-time evaluation device and method, relates to the basic physical property measurement technical field of natural gas hydrate, and comprises a hydrate core triaxial productivity evaluation reaction kettle, a pressure maintaining system, a temperature control system, a gas-liquid collection and analysis system and a data acquisition system. The method is characterized in that: the faithful natural gas hydrate core is transferred into the hydrate core triaxial productivity evaluation reaction kettle; the pressure control system and the temperature control system are adjusted to simulate the pressure and temperature environment in the actual stratum mining process; the gas-liquid collection and analysis system is used to completely separate the gas and liquid generated by the hydrate productivity evaluation device and to perform real-time detection, the gas chromatograph is used to analyze the hydrate decomposition gas composition, the data acquisition system is used to record and analyze the decomposition rule of the hydrate in the core and the sediment deformation, and the productivity in the whole reservoir is predicted, so that guidance is provided for the mining of the hydrate in the reservoir.

This invention discloses a quantitative prediction method for water and sand production from natural gas hydrates, addressing the problem of the inability to quantitatively predict water and sand production in natural gas hydrate reservoirs during depressurization extraction. This invention employs multiple sets of experiments to simulate formation physical parameters, performing hydrate decomposition under different depressurization regimes and collecting water and sand production data. Finally, it establishes a cloud map of water and sand production data under different production regimes. Through this cloud map, quantitative indicators of water and sand production under a specific extraction regime can be quickly accessed, and by using certain conversion relationships, the actual water and sand production data in production wells can be obtained, thus providing reasonable guidance for the formulation of production parameters. The technical approach provided by this invention can be applied to the oil and gas field, such as sandstone and mudstone interbedded oil and gas fields, to establish quantitative prediction models and charts for water and sand production, enabling the widespread application of the invention.

The invention relates to a circulating pressure drop method for exploiting a natural gas hydrate reservoir with underlying gas. The method comprises the following steps: synthesizing a natural gas hydrate reservoir with underlying gas by utilizing a reactor capable of applying confining pressure; the mining process of the natural gas hydrate reservoir is divided into a circulation process in which a pressure drop stage and a well closing stage are alternately arranged; in the pressure drop stage, redundant gas is released through a pressure reducing valve connected with a mining wellhead, and the reservoir pressure is reduced to a set value; in the well closing stage, after the pressure drop reaches the target set value, the control valve connected with the pressure reducing valve is closed to close the mining well; and after a set well closing period is reached, the mining well is opened until hydrate decomposition is completed. According to the method, the exploitation process of the hydrate is further simulated by simulating the exploitation structure, the hydrate decomposition and free gas release processes in the exploitation gas production process are quantitatively analyzed, and experimental data and scientific basis are provided for exploitation of natural gas hydrate reservoirs containing underlying gas.

The present application relates to the technical field of self-repairing microcapsules, and discloses a cement temperature inhibition and crack self-repairing microcapsule, a preparation method and application thereof, which comprises a core material and a shell material covering the core material; the core material is composed of a phase change epoxy compound and a low phase change temperature material at a mass ratio of (7-9):(1-3); the shell material is formed by free radical polymerization of an amino-containing olefin oil-soluble monomer and a flexible oil-soluble diene monomer; a to-be-polymerized system is obtained by mixing the core material with a dispersing agent and a monomer; and an initiator solution is added to obtain the microcapsule through a two-stage polymerization reaction. The microcapsule can effectively inhibit the hydration heat release of cement slurry to maintain the stability of the hydrate formation, and simultaneously realize the efficient self-repairing of micro-cracks in the cement stone, thereby solving the two core technical problems of hydrate decomposition induced by hydration heat in the cementing process of the natural gas hydrate layer and micro-cracks in the service process of the cement stone, ensuring the cementing quality, and realizing the safe and efficient development of resources.

The invention relates to a numerical simulation method for superficial layer gas reservoir depressurization development of overlying hydrate considering heat-fluid-solid-chemical multi-field coupling, which comprises the following steps: integrating multi-source data of a target area, and constructing a superlying hydrate and superficial layer gas reservoir mine field scale three-dimensional geologic model; establishing an oil reservoir numerical simulation model based on the three-dimensional geologic model, and establishing a three-phase four-field coupling mathematical model in combination with key parameters of a heat-fluid-solid-chemical field of a target area; determining natural gas hydrate phase equilibrium curve parameters based on a reservoir numerical simulation model; setting a well position, and preliminarily setting a production system in combination with oil reservoir productivity, permeability, fluidity and reservoir thickness information; solving the mathematical model by utilizing numerical reservoir simulation software, carrying out sensitivity analysis on key parameters and natural gas hydrate phase equilibrium curve parameters according to a production system, and quantitatively describing the change trend of hydrate decomposition and secondary generation in the hydrate reservoir initial distribution and depressurization exploitation process; the method can quantify the influence of hydrates on shallow gas development indexes.