Solid gas hydrate stabilizer composition, method of making solid gas hydrate, solid gas hydrate

Abstract

The application relates to the technical field of natural gas safe storage and transportation, and discloses a solid gas hydrate stabilizer composition and application thereof, a method for preparing solid gas hydrate and the solid gas hydrate. The composition contains the following components which are mixedly stored or independently stored: a solidified hole blocking agent, a structure reinforcing agent, the solidified hole blocking agent is a non-polar organic liquid with a freezing point lower than an ice point; and the structure reinforcing agent is an organic high molecular compound and a hydrophilic organic liquid with a content weight ratio of 0.01-0.1:1. The solid gas hydrate stabilizer composition provided by the application can solidify and block the pore channels of the solid gas hydrate, and simultaneously form a reticular crosslinked structure in the pore channels, thereby reducing the decomposition rate of the solid gas hydrate, and improving the structural stability of the solid gas hydrate in a storage state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas safe storage and transportation, in particular, to a solid gas hydrate stabilizer composition and application thereof, a method for preparing solid gas hydrate, solid gas hydrate and a method for evaluating structural stability of solid gas hydrate in a storage state. BACKGROUND

[0002] Solid gas hydrate is a non-stoichiometric crystal material formed by small gas molecules (methane, ethane, hydrogen sulfide, etc.) and water molecules under low temperature and high pressure conditions. Hydrate method for storing and transporting natural gas is one of the hydrate-related derivative technologies, which utilizes the gas storage and transportation characteristics of hydrate itself to realize gas storage and transportation. In theory, 1 volume of solid hydrate can store and transport 160-180 volumes of natural gas molecules.

[0003] Compared with other existing natural gas storage and transportation methods, the hydrate method for storing and transporting natural gas has the following advantages: (1) The preparation process of hydrate is environmentally friendly, only some water and low-concentration accelerators (ppm level) are used; (2) The guest molecules (methane) are stored in the form of individual molecules, and almost all of them can be recovered and utilized by simple depressurization or heating; (3) The generation temperature and pressure of hydrate are mild in the presence of a hydrate accelerator; (4) The gas storage capacity is relatively high; (5) The storage process is very safe and reliable due to the non-explosive nature of the gas.

[0004] The application of solid hydrate gas storage technology includes three main stages: rapid preparation of hydrate, safe storage and transportation, and efficient decomposition and recovery of hydrate. A large number of researchers have explored the strengthening of the hydrate preparation process, such as using mechanical strengthening method and chemical promotion method for physical or chemical strengthening. The safe storage and transportation of solid hydrate is also of great significance to the development of hydrate gas storage technology. Since hydrate has a significant self-protection effect at -5℃ to -35℃, a certain thickness of ice layer is formed on the surface of the hydrate to inhibit the diffusion of the decomposition gas, thereby sealing the solid hydrate inside the ice layer and reducing the decomposition rate of the hydrate, thereby achieving the purpose of safe storage and transportation.

[0005] However, domestic and foreign researchers have found that the ice layer formed by the freezing of water phase alone is too thin to inhibit the continuous decomposition of hydrate, which not only leads to unnecessary decomposition loss of solid hydrate during storage and transportation, but also brings serious safety hazards due to the decomposition of high-pressure gas.

[0006] However, there are few reports on how to reduce the decomposition rate of hydrate and improve the structural stability of solid hydrate in a storage state by suitable physical or chemical methods while ensuring high gas storage capacity of solid hydrate.

[0007] CN110564472A discloses a method for inhibiting hydrate decomposition and a hydrate storage and transportation method, comprising the following steps: after the hydrate is formed, a hydrate promoter is added on the surface of the hydrate, the hydrate promoter comprises at least one of tetrahydrofuran or cyclohexane, so that the pressure in the hydrate method gas storage process is reduced, thereby further improving the safety in the gas storage process. However, the prior art uses the method of adding a thermodynamic hydrate promoter, so its inhibitory effect on the hydrate decomposition rate is limited.

[0008] CN109321215A discloses a hydrate decomposition inhibitor suitable for drilling in natural gas hydrate formation, comprising the following mass percentages of raw materials: poly-3-methylene-2-pyrrolidone 0-100%, lecithin 0-100%, poly-N-vinyl pyrrolidone 0-100%. However, the prior art only inhibits the decomposition of hydrate by adding a hydrate decomposition inhibitor, so its inhibitory effect on the hydrate decomposition rate is also limited.

[0009] CN108301816A discloses a method and device for evaluating the influence of chemical agents on the decomposition characteristics of natural gas hydrates, but the prior art does not involve specific means for inhibiting the decomposition of natural gas hydrates.

[0010] CN104437290A discloses a complex gas hydrate formation promoter and a preparation method thereof, the hydrate formation promoter is a mixed solution formed by dissolving nano-dispersed particles and a gemini surfactant in water, the prior art enhances the mass and heat transfer process to improve the hydrate formation rate, but it does not involve how to inhibit the decomposition of hydrate. SUMMARY

[0011] The purpose of the present application is to solve the problems of high decomposition loss rate and insufficient structural stability in the solid gas hydrate storage and transportation process.

[0012] To achieve the above purpose, the first aspect of the present application provides a solid gas hydrate stabilizer composition, which contains the following components mixed and stored or stored independently:

[0013] a solidified pore plugging agent and a structure reinforcing agent,

[0014] The solidified pore plugging agent is a non-polar organic liquid with a freezing point lower than the freezing point;

[0015] The structure reinforcing agent is an organic high molecular compound and a hydrophilic organic liquid with a content weight ratio of 0.01-0.1:1;

[0016] The content ratio of the solidified pore plugging agent to the structure reinforcing agent is 1:0.1-0.2.

[0017] The second aspect of the present application provides a method for preparing a solid-state gas hydrate, which is performed by using the composition described in the aforementioned first aspect, comprising:

[0018] (1) performing a first contact reaction of a solidifying plugging agent, a hydrophilic surfactant and a gas in the presence of an aqueous phase to obtain a mixture I;

[0019] (2) performing a second contact reaction of the mixture I and a structure strengthening agent to obtain the solid-state gas hydrate.

[0020] The third aspect of the present application provides a solid-state gas hydrate prepared by the method described in the aforementioned second aspect.

[0021] The fourth aspect of the present application provides a method for evaluating the structural stability of a solid-state gas hydrate in a storage state, which comprises:

[0022] (I) recording the system pressure P0 at the initial storage time of the solid-state gas hydrate, the system pressure P d , then heating the system to completely decompose the solid-state gas hydrate in the system, and recording the system pressure P e at the complete decomposition time;

[0023] (II) calculating the structural stability parameter SS of the solid-state gas hydrate by using the formula (1) to evaluate the structural stability of the solid-state gas hydrate in a storage state;

[0024] SS% = [1- (P d -P0) / (P e -P0)] x 100% Formula (1);

[0025] The solid-state gas hydrate is the solid-state gas hydrate described in the aforementioned third aspect.

[0026] The units of P0, P d , and P e are kPa.

[0027] The present application has at least the following advantages over the prior art:

[0028] (1) The solid-state gas hydrate stabilizer composition provided by the present application can solidify and plug the pores of the solid-state hydrate, and at the same time form a reticular crosslinked structure in the pores, thereby reducing the decomposition rate of the solid-state gas hydrate, and thus improving the structural stability of the solid-state gas hydrate in a storage state.

[0029] (2) The method for preparing the solid gas hydrate has simple operation, and the structural stability of the prepared solid gas hydrate can be obviously improved, and has a wide application prospect in the field of hydrate method natural gas storage and transportation.

[0030] (3) The method for evaluating the structural stability of the solid gas hydrate in the storage state only needs to record the pressure change of the solid gas hydrate in the storage state to calculate the structural stability parameter of the solid gas hydrate in the storage state, can quantitatively evaluate the performance of the solid gas hydrate stabilizer composition, and has the characteristics of strong operability, convenient calculation, high accuracy and the like. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a pressure and temperature change curve diagram of a solid gas hydrate generation, storage and decomposition process; wherein, the curve of section A is a solid gas hydrate generation and stable stage, the curve of section B is a stage of cooling the solid gas hydrate to a storage temperature, the curve of section C is a stage of decompressing the solid gas hydrate to a storage pressure and a storage stage, and the curve of section D is a stage of heating and decomposing the solid gas hydrate. DETAILED DESCRIPTION

[0032] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact numerical values of the endpoints of the ranges and the separate points are not to be understood as being strictly limited to the exact numerical values recited. At the very least, each minimum numerical limitation should at least be construed in the context as permitting some slack between the minimum and maximum values to allow for modifications. Numerous specific examples are described herein. Any combination of these specific examples and / or ranges are included within the scope of the present disclosure. Any specific examples and / or ranges are included within the scope of the present disclosure.

[0033] As described previously, the first aspect of the present application provides a solid gas hydrate stabilizer composition, which contains the following components mixed and stored or stored independently:

[0034] a solidification pore plugging agent, a structure strengthening agent,

[0035] The solidification pore plugging agent is a non-polar organic liquid with a freezing point lower than the freezing point.

[0036] The structure strengthening agent is an organic high molecular compound and a hydrophilic organic liquid with a content weight ratio of 0.01-0.1:1.

[0037] The content ratio of the solidification pore plugging agent to the structure strengthening agent is 1:0.1-0.2.

[0038] Preferably, the non-polar organic liquid is selected from at least one of n-undecane, n-dodecane and n-tridecane.

[0039] Preferably, the hydrophilic organic liquid is selected from at least one of tetrahydrofuran compounds.

[0040] Preferably, the tetrahydrofuran compound is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofurfuryl alcohol, tetrahydrofurfuryl alcohol methyl ester, tetrahydrofurfuryl acrylate.

[0041] Preferably, the organic high molecular compound is a cellulose compound and a vinyl copolymer with a content ratio of 1:0.1-10. In this preferred case, the inventors of the present application have found that the solid gas hydrate prepared using this composition has better structural stability.

[0042] Preferably, the cellulose compound is selected from at least one of hydroxypropyl methyl cellulose, hydroxyethyl cellulose, cellulose acetate butyrate, diethylaminoethyl cellulose.

[0043] Preferably, the vinyl copolymer is selected from at least one of polyvinylpyrrolidone, cross-linked polyvinylpyrrolidone, polyvinyl acetate, vinylpyrrolidone-vinyl acetate copolymer, poly(methyl vinyl ether-co-maleic acid).

[0044] As described above, the second aspect of the present application provides a method for preparing a solid hydrate, which is performed using the composition described in the aforementioned first aspect, comprising:

[0045] (1) performing a first contact reaction of the pore blocking agent, the hydrophilic surfactant and the gas in the presence of an aqueous phase to obtain a mixture I;

[0046] (2) performing a second contact reaction of the mixture I and the structure strengthening agent to obtain the solid gas hydrate.

[0047] It should be noted that the aqueous phase can be a pure water system or an aqueous solution system containing a hydrate promoter, which can be selected by those skilled in the art in combination with known means in the art. Exemplarily, the hydrate promoter can be an amino acid compound, sodium dodecyl sulfonate, etc. The amino acid compound can be leucine, norvaline, histidine, etc.

[0048] It should be noted that the present application does not have special limitations on the type of the gas, and exemplarily, the gas can be methane, ethane, hydrogen sulfide, etc., which should not be understood as a limitation on the present application by those skilled in the art.

[0049] Preferably, the amount of the pore blocking agent is 1.0-5.0 g, the amount of the hydrophilic surfactant is 0.01-0.1 g, and the amount of the structure strengthening agent is 0.1-1.0 g, relative to 100 mL of the aqueous phase.

[0050] According to a preferred embodiment, in step (1), the first contact reaction is carried out under conditions of a reaction temperature of 1-10°C, a reaction pressure of not less than 3500 kPa, and a reaction time of 60-120 min. More preferably, in step (1), the reaction conditions of the first contact reaction are 80-100 min.

[0051] According to another preferred embodiment, in step (2), the second contact reaction is carried out under conditions of a reaction temperature of -5°C to -35°C, a reaction pressure of not less than 3500 kPa, and a reaction time of 60-120 min. More preferably, in step (2), the reaction conditions of the second contact reaction are 80-100 min.

[0052] Preferably, the hydrophilic surfactant is at least one selected from hydrophilic non-ionic surfactants.

[0053] More preferably, the hydrophilic non-ionic surfactant is at least one selected from polyoxyethylene sorbitan fatty acid ester compounds and betaine compounds.

[0054] Particularly preferably, the hydrophilic surfactant is a combination of polyoxyethylene sorbitan fatty acid ester compounds and betaine compounds in a weight ratio of 1:0.5-5.

[0055] In the present application, according to a preferred embodiment, the method for preparing the solid hydrate comprises the following steps:

[0056] (1) stirring a plugging agent and a hydrophilic surfactant in the presence of an aqueous phase, and then performing a first contact reaction with a gas under conditions of a temperature of 1-10°C and a pressure of not less than 3500 kPa for 60-120 min to obtain a mixture I;

[0057] (2) ultrasonically treating the mixture I and then performing a second contact reaction under conditions of a temperature of -5°C to -35°C and a pressure of not less than 3500 kPa for 60-120 min to obtain the solid gas hydrate.

[0058] Preferably, the stirring is carried out under conditions of a stirring speed of 90-120 rpm, a temperature of 20-40°C, and a time of 10-30 min.

[0059] Preferably, the ultrasonic treatment is carried out under conditions of a frequency of 50-75 Hz, a temperature of 1-10°C, and a time of 5-10 min.

[0060] As described above, the fourth aspect of the present application provides a method for evaluating the structural stability of a solid gas hydrate in a storage state, the method comprising:

[0061] (I) recording the system pressure P0 at the initial storage time of the solid gas hydrate, the system pressure P at a certain time after storage, and the system pressure P at the complete decomposition time of the solid gas hydrate d , and then heating the system to completely decompose the solid gas hydrate in the system while recording the system pressure P at the complete decomposition time e ;

[0062] (II) calculating the structural stability parameter SS of the solid gas hydrate using the formula (1) to evaluate the structural stability of the solid gas hydrate in a storage state;

[0063] SS% = [1 - (P d -P0) / (P e -P0)] x 100% Formula (1);

[0064] wherein the solid gas hydrate is the solid gas hydrate described in the third aspect above;

[0065] The units of P0, P d , and P e are all kPa.

[0066] The present application will be described in detail below through examples.

[0067] In the following examples, the raw materials used are commercially available unless otherwise specified.

[0068] In the present application, room temperature means 25±2℃ unless otherwise specified.

[0069] Solidification hole blocking agent

[0070] n-tridecane: purity of 99wt%, commercially available from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0071] n-dodecane: purity of 98wt%, commercially available from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0072] Structural reinforcing agent:

[0073] 2-methyltetrahydrofuran (Y1): purity of >99wt%, commercially available from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0074] methyltetrahydrofuran-2-carboxylate (Y2): purity of >98wt%, commercially available from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0075] Hydroxypropyl methylcellulose (X1): Type I, viscosity 400 mPa·s, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0076] Hydroxyethyl cellulose (X2): 5700 mPa·s (25° C.), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0077] Polyvinylpyrrolidone (PVP): K-90, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0078] Hydrophilic surfactants:

[0079] Tween 80: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0080] Tween 20: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0081] 7-Hydroxybetaine (T1): Purity>99 wt%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0082] Example 1

[0083] (1) At room temperature, 10 mL of pure water, 0.1 g of a curing pore plugging agent, and 0.002 g of a hydrophilic surfactant were stirred at 100 rpm for 20 min, and then subjected to a first contact reaction with methane in a reactor at a temperature of 2°C and a pressure of 6745 kPa for 90 min to obtain a mixture I;

[0084] The solidifying pore plugging agent is n-tridecane, and the hydrophilic surfactant is Tween 20 and 7-hydroxybetaine in a weight ratio of 1:1;

[0085] (2) 0.02 g of a structure-enhancing agent was added to the above-mentioned reactor, and a pulse ultrasonic generator (60 Hz) at the bottom of the reactor was turned on for ultrasonic treatment for 5 minutes. The temperature was then lowered to -10°C and the pressure was maintained at 6745 kPa for a second contact reaction for 90 minutes to obtain solid gas hydrate S1.

[0086] The structural reinforcing agent comprises 2-methyltetrahydrofuran, methyl cellulose and polyvinyl pyrrolidone in a weight ratio of 1:0.01:0.01.

[0087] Example 2-18

[0088] Examples 2-18 were prepared using a method similar to that of Example 1, except that the types, amounts, and reaction conditions of the components were different. The stirring and ultrasonic treatment conditions were consistent in each example and were the same as in Example 1. For details, see Table 1.

[0089] Example 19

[0090] The solid-state gas hydrate was prepared by the similar method of Example 1, except that:

[0091] The structural enhancer in step (2) was 2-methyltetrahydrofuran and methyl cellulose with a content weight ratio of 1:0.02; and the rest conditions were the same as those in Example 1.

[0092] The solid-state gas hydrate S19 was prepared.

[0093] Example 20

[0094] The solid-state gas hydrate was prepared by the similar method of Example 1, except that:

[0095] The structural enhancer in step (2) was 2-methyltetrahydrofuran and polyvinylpyrrolidone with a content weight ratio of 1:0.02; and the rest conditions were the same as those in Example 1.

[0096] The solid-state gas hydrate S20 was prepared.

[0097] Comparative Example 1

[0098] (1) 10 mL of pure water and methane were subjected to a first contact reaction in a reaction kettle at a temperature of 2°C and a pressure of 6685 kPa for 90 min to obtain a mixture I;

[0099] (2) The mixture I was subjected to ultrasonic treatment by a pulse ultrasonic generator (60 Hz) for 5 min, and then was subjected to a reaction at a temperature of -10°C and a pressure of 6685 kPa for 90 min to obtain a solid-state gas hydrate DS1.

[0100] Comparative Example 2

[0101] The solid-state gas hydrate was prepared by the similar method of Comparative Example 1, except that:

[0102] The temperature in step (1) was 2°C and the pressure was 6715 kPa; the temperature in step (2) was -20°C and the pressure was 6715 kPa; and the rest conditions were the same as those in Comparative Example 1.

[0103] The solid-state gas hydrate DS2 was prepared.

[0104] Comparative Example 3

[0105] The solid-state gas hydrate was prepared by the similar method of Comparative Example 1, except that:

[0106] The pure water in step (1) further contains 0.05 wt% of sodium dodecyl sulfate; the pressure in step (1) and step (2) is 6796 kPa; and the rest of the conditions are the same as those in Comparative Example 1.

[0107] A solid gas hydrate DS3 was prepared.

[0108] Comparative Example 4

[0109] This comparative example used a method similar to that in Comparative Example 3 to prepare a solid gas hydrate, except that:

[0110] The temperature in step (1) was 2°C and the pressure was 6836 kPa; the temperature in step (2) was -20°C and the pressure was 6836 kPa; and the rest of the conditions were the same as those in Comparative Example 3.

[0111] A solid gas hydrate DS4 was prepared.

[0112] Comparative Example 5

[0113] This comparative example used a method similar to that in Comparative Example 1 to prepare a solid gas hydrate, except that:

[0114] The pure water in step (1) further contains 0.05 wt% of leucine; the pressure in step (1) and step (2) is 6805 kPa; and the rest of the conditions are the same as those in Comparative Example 1.

[0115] A solid gas hydrate DS5 was prepared.

[0116] Comparative Example 6

[0117] This comparative example used a method similar to that in Comparative Example 5 to prepare a solid gas hydrate, except that:

[0118] The temperature in step (1) was 2°C and the pressure was 6520 kPa; the temperature in step (2) was -20°C and the pressure was 6520 kPa; and the rest of the conditions were the same as those in Comparative Example 5.

[0119] A solid gas hydrate DS6 was prepared.

[0120] Table 1

[0121]

[0122]

[0123] Note: 0.02 = 1:0.01:0.01 means that the total amount of the structure stabilizer is 0.02 g, and the weight ratio of Y1, X1 and PVP is 1:0.01:0.01; 0.03 = 1:0.02:0.02, 0.04 = 1:0.03:0.03, etc. have similar definitions.

[0124] Table 1 (continued)

[0125]

[0126]

[0127] Table 1 (continued)

[0128]

[0129] Table 1 (continued)

[0130]

[0131]

[0132] Test Example

[0133] After the pressure of the reactor containing the solid gas hydrate prepared in each example and comparative example is reduced to 100 kPa (P0) and the exhaust valve is closed, the pressure (P1) in the reactor is recorded after the reactor is stored at -10℃ for 2 h; then the reactor is warmed to 30℃, and the pressure (P2) in the reactor is recorded after the solid gas hydrate in the reactor is completely decomposed; then the structural stability parameter SS of the solid gas hydrate is calculated by using formula (1), and the specific results are shown in Table 2. d e

[0134] Table 2

[0135]

[0136]

[0137] As can be seen from the results in Table 2, the solid gas hydrate prepared by using the solid gas hydrate stabilizer composition and the preparation method provided by the present application has better structural stability, and therefore has a broad application prospect in the field of hydrate method natural gas storage and transportation.

[0138] ​​The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A solid gas hydrate stabilizer composition, characterized in that: The composition comprises: Curing plugging agent and structural strengthening agent, The curing pore plugging agent is selected from at least one of n-undecane, n-dodecane and n-tridecane; The structural strengthening agent is an organic polymer compound and a hydrophilic organic liquid in a weight ratio of 0.01-0.1:1; The hydrophilic organic liquid is selected from at least one of tetrahydrofuran compounds; The organic polymer compound is a cellulose compound and a vinyl copolymer in a content ratio of 1:0.1-10; The weight ratio of the solidifying pore plugging agent to the structural strengthening agent is 1:0.1-0.

2.

2. The composition according to claim 1, wherein The tetrahydrofuran compound is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran-2-carboxylic acid, methyl tetrahydrofuran-2-carboxylate, and tetrahydrofuran acrylate.

3. The composition according to claim 1 or 2, wherein The cellulose compound is at least one selected from hydroxypropyl methylcellulose, hydroxyethyl cellulose, cellulose acetate butyrate, and diethylaminoethyl cellulose; and / or The vinyl copolymer is at least one selected from polyvinyl pyrrolidone, cross-linked polyvinyl pyrrolidone, polyvinyl acetate, vinyl pyrrolidone-vinyl acetate copolymer, and poly(methyl vinyl ether copolymerized with maleic acid).

4. A method for preparing solid gas hydrate, characterized in that: The method is carried out using the composition according to any one of claims 1 to 3, comprising: (1) In the presence of an aqueous phase, a solidified pore plugging agent, a hydrophilic surfactant, and a gas are subjected to a first contact reaction to obtain a mixture I; (2) subjecting the mixture I to a second contact reaction with a structure reinforcing agent to obtain the solid gas hydrate.

5. The method according to claim 4, wherein Relative to 100 mL of the aqueous phase, the amount of the solidifying pore plugging agent is 1.0-5.0 g, the amount of the hydrophilic surfactant is 0.01-0.1 g, and the amount of the structural strengthening agent is 0.1-1.0 g.

6. The method according to claim 4 or 5, wherein: In step (1), the conditions of the first contact reaction at least meet the following requirements: reaction temperature of 1-10°C, reaction pressure of not less than 3500 kPa, reaction time of 60-120 min; and / or, In step (2), the conditions of the second contact reaction at least meet the following requirements: reaction temperature is -5°C to -35°C, reaction pressure is not less than 3500 kPa, and reaction time is 60-120 min.

7. The method according to claim 4 or 5, wherein: The hydrophilic surfactant is selected from at least one of hydrophilic nonionic surfactants.

8. A solid gas hydrate prepared by the method according to any one of claims 4 to 7.

9. A method for evaluating the structural stability of solid gas hydrates in storage state, characterized in that: The method includes: (I) Recording the system pressure at the initial storage time of solid gas hydrate P 0. System pressure after storage for a certain period of time P d Then the system is heated to completely decompose the solid gas hydrate in the system, and the system pressure at the moment of complete decomposition is recorded. P e ; (II) The structural stability parameter of solid gas hydrate is calculated using the formula shown in formula (1): SS , the structural stability parameter SS Ability to evaluate the structural stability of solid gas hydrates in storage state; SS %=[1-( P d - P 0) / （P e - P 0)] × 100% formula (1); Wherein, the solid gas hydrate is the solid gas hydrate described in claim 8; P 0. P d as well as P e The unit is kPa.

Images