Measurement device and measurement calculation method for saturation of saturated hydrate sediment sample based on replacement method

Abstract

The invention relates to a device and a method for measuring saturation of a saturated hydrate sediment sample based on a replacement method, and the device comprises a high-pressure reaction kettle, a sample, a confining pressure system, a back pressure system, a measuring system and a pore pressure system. And the saturation degree of the saturated hydrate sediment sample is measured, so that the accuracy of establishing the relationship between the saturation degree and the physical property of the saturated hydrate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring the saturation of experimentally prepared hydrate sediment samples, and in particular relates to a measuring device and a measuring calculation method for the saturation of saturated hydrate sediment samples based on a replacement method. Background Art

[0002] Marine hydrates are a relatively clean fossil fuel resource and may be the key to easing the transition to renewable energy in the future. The development of marine hydrates has attracted widespread attention from scholars around the world. At present, the exploration and development of hydrates is still in the trial mining stage, and there are related problems such as unclear exploration of the physical properties of hydrate sediments. Therefore, completing the exploration of hydrate physical properties in the laboratory is an important guarantee for accelerating the realization of hydrate field development.

[0003] Under certain temperature and pressure conditions, natural gas and water will form hydrates, but there is no coexistence of gas and water in stable hydrate samples. Therefore, from this perspective, laboratory synthetic hydrate samples are divided into two types, namely saturated gas hydrate sediment samples and saturated water hydrate sediment samples. Saturated gas hydrate sediment samples are prepared by pre-mixing a certain amount of water in the sample and passing excess gas in the experiment. Saturated water hydrate sediment samples are obtained by liquid circulation and displacement after the preparation of saturated gas hydrate sediment samples. Since the pores of saturated water hydrate sediment samples are liquid, they are closer to the actual occurrence environment of seabed hydrates, so it is more valuable to study them. The saturation measurement methods in saturated water hydrates include water consumption method and gas consumption method. Among them, the water consumption method is difficult to ensure the complete conversion of the pre-added water, which affects the saturation calculation. The gas consumption method has extremely high requirements for the experimental instrument. It is necessary to ensure that the test instrument is completely sealed and there is no leakage during the test process. This is difficult to achieve in the experiment. Moreover, when calculating the saturation of hydrated gas by the gas consumption, the selection range of an important parameter in the calculation process, the hydrate hydration number, is too wide, which can be 150~170, seriously affecting the accuracy of the saturation calculation. Accurate calculation of the saturation of hydrate sediments is crucial to establish the relationship between hydrate saturation and physical properties. However, it is difficult to accurately measure the saturation of hydrate sediment samples using existing experimental devices. Therefore, it is urgent to establish a saturation measurement device and measurement calculation method for hydrate sediment samples to improve the accuracy of saturation calculation of hydrate sediments, thereby improving the accuracy of establishing the relationship between hydrate saturation and physical properties. Summary of the invention In view of at least one of the problems in the above-mentioned prior art, the object of the present invention is to provide a measuring device and a measuring calculation method for the saturation of a saturated hydrate sediment sample based on a replacement method. The measuring device obtains a saturated hydrate sediment sample by the replacement method and measures the saturation of the saturated hydrate sediment sample, so as to improve the accuracy of establishing the relationship between the saturation of the saturated hydrate and the physical properties.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A device for measuring the saturation of a hydrate sediment sample based on a replacement method, characterized in that it comprises: A high-pressure reactor, the interior of which is a confining pressure chamber filled with confining pressure liquid; A sample is arranged in the confining pressure chamber, the top of the sample is connected to the top surface of the high-pressure reactor, the bottom of the sample is connected to the bottom surface of the high-pressure reactor, the outer wall of the sample is wrapped in a flexible sleeve, and the flexible sleeve is used to isolate the sample from the confining pressure liquid; the sample has pores; A confining pressure system, comprising a confining pressure pump, wherein the confining pressure pump is connected to the confining pressure chamber through a pipeline; A back pressure system, comprising a back pressure pump and a back pressure valve, wherein the back pressure pump, the back pressure valve and the confining pressure chamber are connected in sequence through pipelines; A measuring system, comprising a pore pressure outlet valve, a gas flow meter and a waste gas recovery bottle connected in sequence, wherein the pore pressure outlet valve is connected to the top of the sample through a pore pressure outlet pipe; The pore pressure system comprises a liquid pore pressure injection system and a gas pore pressure injection system, wherein the liquid pore pressure injection system and the gas pore pressure injection system are connected to the bottom of the sample through a pore pressure inlet pipe.

[0005] Preferably, a confining pressure valve is provided between the confining pressure pump and the confining pressure chamber.

[0006] Preferably, a drying bottle is provided between the pore pressure outlet valve and the gas flow meter.

[0007] Preferably, the liquid pore pressure injection system comprises a liquid pore pressure inlet valve, a liquid pore pressure pipeline pressure gauge and a liquid pore pressure injection pump which are connected in sequence, and the liquid pore pressure inlet valve is connected to the pore pressure inlet pipe through a pipeline.

[0008] Preferably, the gas pore pressure injection system comprises a gas pore pressure inlet valve, a gas pore pressure pipeline pressure gauge, a pressure reducing valve and a high-pressure gas cylinder which are connected in sequence, and the gas pore pressure inlet valve is connected to the pore pressure inlet pipe through a pipeline.

[0009] Preferably, the high-pressure reactor is placed in an air bath thermostat.

[0010] A method for measuring and calculating the saturation of a saturated hydrate sediment sample is based on any one of the above-mentioned saturation measurement devices for saturated hydrate sediment samples based on the replacement method, and comprises the following steps: Obtaining the initial pore volume of hydrate sediment samples V y ; The saturated hydrate sediment samples were obtained by replacement method; Obtaining the replaced pore volume of hydrate sediment samples V h ; The saturation of the hydrate sediment sample is calculated using the following formula:

[0011] in, S h is the hydrate saturation, V y is the initial pore volume, V h is the pore volume after replacement.

[0012] Preferably, when obtaining the initial pore volume of the hydrate sediment sample V y In the steps, A set mass of sediment is taken for sampling to obtain a sample, and the confining pressure of the confining pressure cavity and the pore pressure of the gas pore pressure injection system are adjusted to a preset pressure, at which the pore pressure is the initial pore pressure P2; Turn on the liquid pore pressure injection pump to pump liquid to displace pore gas. When liquid flows out of the pore pressure outlet, record the injected liquid volume as the initial pore volume. V y .

[0013] Preferably, after obtaining the replaced pore volume of the hydrate sediment sample, V h The steps include: The same mass of sediment is refilled into the sample, the confining pressure and the pore pressure are adjusted to a preset pressure, and hydrate generation begins in the pores; When the pore pressure stops decreasing, hydrate formation is complete and liquid replacement begins; Close the gas pore pressure inlet valve, open the liquid pore pressure injection pump, increase the pipeline pressure to a level higher than the initial pore pressure P2, and then open the liquid pore pressure inlet valve; Record the exhaust gas volume V 1 and injected liquid volume V 泵 ; When liquid flows out of the pore pressure outlet, the pore gas in the sample is completely replaced; Reduce the pore pressure to the initial pore pressure P2, record the volume of gas discharged during the pressure change, and the volume of liquid discharged during the process of restoring the initial pressure. V 排 ; Measuring room temperature T 1 and hydrate temperature T 2 .

[0014] Preferably, the pore volume after replacement is V h It can be calculated by two methods, namely water injection method and exhaust method. The calculation formula of the water injection method is as follows:

[0015] in, V h-water Displaced pore volume calculated for injected water V h , V 泵 is the pumping volume of the liquid pore pressure injection pump, V 排 The volume of liquid discharged during the process of restoring the initial pressure; The calculation formula of the exhaust method is as follows: ; ; ; in, P 1 , P 2 are atmospheric pressure and initial pore pressure, respectively. V 1 is the exhaust gas volume, V h-gas Calculate the pore volume for the gas after displacement, T 1 , T 2 are room temperature and hydrate temperature, respectively. Z 1 , Z 2 are the gas compressibility factors at different pressures, n is the amount of gas substance, R is the gas constant.

[0016] The present invention adopts the above technical solution, which has the following advantages: 1. The present invention provides a device for measuring the saturation of a hydrate sediment sample based on a replacement method, which obtains a saturated hydrate sediment sample through the replacement method and measures the saturation of the hydrate sediment sample, so as to improve the accuracy of establishing the relationship between the saturation of the hydrate and the physical properties.

[0017] 2. The method for measuring and calculating the saturation of a saturated hydrate sediment sample provided by the present invention is based on the direct pore volume ratio, has strict physical meaning, and can more accurately calculate the saturation of a saturated hydrate sediment sample. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of a device for measuring the saturation of a hydrate sediment sample based on a replacement method provided in Example 1 of the present invention.

[0018] Figure 2 It is a flow chart of the steps of the method for measuring and calculating the saturation of a saturated hydrate sediment sample provided in the second embodiment of the present invention.

[0019] Markings in the accompanying drawings: 100 is a sample, 1 is a high-pressure reactor, 2 is a confining pressure chamber, 3 is a confining pressure valve, 4 is a confining pressure pump, 5 is a back pressure valve, 6 is a back pressure pump, 7 is a pore pressure outlet valve, 8 is a drying bottle, 9 is a gas flow meter, 10 is a waste gas recovery bottle, 11 is a pore pressure inlet valve, 12 is a liquid pore pressure inlet valve, 13 is a liquid pore pressure pipeline pressure gauge, 14 is a liquid pore pressure injection pump, 15 is a gas pore pressure inlet valve, 16 is a gas pore pressure pipeline pressure gauge, 17 is a pressure reducing valve, 18 is a high-pressure gas cylinder, and 19 is a temperature control system. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. The direction of the arrow in the figure represents the direction of liquid flow.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "assembly", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] The present invention provides a measurement device and a measurement calculation method for the saturation of a saturated hydrate sediment sample based on a replacement method. The measurement device obtains a saturated hydrate sediment sample by the replacement method and measures the saturation of the saturated hydrate sediment sample, so as to improve the accuracy of establishing the relationship between the saturation of the saturated hydrate and the physical property.

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] Example 1 Please refer to Figure 1 As shown, a device for measuring the saturation of a hydrate sediment sample based on a replacement method provided in this embodiment includes a high-pressure reactor 1, a sample 100, a confining pressure system, a back pressure system, a measuring system and a pore pressure system; The high-pressure reactor 1 can be a flexible high-pressure reactor or a rigid reactor. The outer side of the high-pressure reactor 1 is a supporting shell, and the interior of the high-pressure reactor 1 is a confining pressure chamber 2 filled with confining pressure liquid; the confining pressure liquid is used to provide confining pressure for the sample 100, and the confining pressure liquid can be water, ethylene glycol or low-temperature hydraulic oil.

[0026] The sample 100 is arranged in the confining pressure chamber 2, the top of the sample 100 is connected to the top surface of the chamber of the high-pressure reactor 1, the bottom of the sample 100 is connected to the bottom surface of the chamber of the high-pressure reactor 1, the outer wall of the sample 100 is wrapped in a flexible sleeve, the flexible sleeve is used to isolate the sample 100 from the confining pressure liquid, and there are pores in the sample; the pore pressure and the confining pressure are independently controlled by the flexible sleeve.

[0027] The confining pressure system includes a confining pressure pump 4 , which is connected to the confining pressure chamber 2 through a pipeline. In the experiment, the confining pressure system provides a pressure source for the confining pressure chamber 2 ; a confining pressure valve 3 is provided between the confining pressure pump 4 and the confining pressure chamber 2 .

[0028] The back pressure system includes a back pressure pump 6 and a back pressure valve 5. The back pressure pump 6, the back pressure valve 5 and the confining pressure chamber 2 are connected in sequence through pipelines. In the experiment, the set pressure of the back pressure valve 5 is set to be the same as the confining pressure. When the confining pressure liquid pressure is higher than the preset confining pressure, the confining pressure liquid is discharged from the back pressure valve 5 to reduce the confining pressure.

[0029] The measurement system includes a pore pressure outlet valve 7, a gas flowmeter 9 and a waste gas recovery bottle 10 which are connected in sequence. The pore pressure outlet valve 7 is connected to the top of the sample 100 through a pore pressure outlet pipe. In the experiment, opening the pore pressure outlet valve 7 can reduce the pore pressure, and the gas volume can be discharged through the gas flowmeter 9, and the waste gas recovery bottle 10 recovers the discharged gas.

[0030] In this embodiment, a drying bottle 8 is provided between the pore pressure outlet valve 7 and the gas flow meter 9. The drying bottle 8 is located at the front end of the gas flow meter 9 and is used to remove water from the gas to improve the measurement accuracy of the gas flow meter 9. The drying bottle 8 can be placed on a balance, and the mass of water removed from the gas can be measured by the balance.

[0031] The pore pressure system includes a liquid pore pressure injection system and a gas pore pressure injection system, and the liquid pore pressure injection system and the gas pore pressure injection system are connected to the bottom of the sample 100 through a pore pressure inlet pipe.

[0032] In this embodiment, a pore pressure inlet valve 11 is provided on the pore pressure inlet pipe, which can be used to close the pore pressure system.

[0033] The liquid pore pressure injection system includes a liquid pore pressure inlet valve 12, a liquid pore pressure pipeline pressure gauge 13 and a liquid pore pressure injection pump 14 which are connected in sequence. The liquid pore pressure inlet valve 12 is connected to the pore pressure inlet pipe through a pipeline; the liquid pore pressure injection pump 14 also includes a liquid storage tank. The liquid pore pressure injection pump 14 provides power for the liquid replacement in the voids of the sample 100 and pumps the liquid in the liquid storage tank into the pores of the sample 100.

[0034] The gas pore pressure injection system includes a gas pore pressure inlet valve 15, a gas pore pressure pipeline pressure gauge 16, a pressure reducing valve 17 and a high-pressure gas cylinder 18 which are connected in sequence. The gas pore pressure inlet valve 15 is connected to the pore pressure inlet pipe through a pipeline. The high-pressure gas cylinder 18 is used as a gas pressure source; the pressure reducing valve 17 is used to control the outflow gas pressure; the gas pore pressure inlet valve 15 is used to disconnect the high-pressure gas cylinder 18 from the high-pressure reactor 1, so that the two form a relatively independent space.

[0035] In this embodiment, the gas pore pressure inlet valve 15 and the liquid pore pressure inlet valve 12 cannot be started at the same time to avoid damage to the equipment caused by the simultaneous influx of gas or liquid.

[0036] In this embodiment, all pipelines are seamless steel pipes, and the volume of the pipelines remains unchanged when the pipeline pressure changes.

[0037] In this embodiment, the autoclave 1 is placed in an air bath thermostat, through which the experimental temperature of the sample 100 can be controlled.

[0038] Example 2 Please refer to Figure 2As shown, this embodiment provides a method for measuring and calculating the saturation of a saturated hydrate sediment sample, which is based on the saturation measurement device of the saturated hydrate sediment sample based on the replacement method in Example 1, and includes the following steps: S01. Obtaining the initial pore volume of hydrate sediment samples V y ; S02, obtaining a saturated hydrate sediment sample by replacement method; S03. Obtaining the replaced pore volume of the hydrate sediment sample V h ; S04. Calculate the saturation of the hydrate sediment sample.

[0039] The saturation calculation formula of hydrate sediment sample is as follows: ; in, S h is the hydrate saturation, V y is the initial pore volume, V h is the pore volume after replacement.

[0040] Specifically, the steps for preparing the saturated hydrate sediment sample and measuring the saturated hydrate sediment sample in the experiment are as follows: Step 1: Take a set mass of sediment for sampling to obtain a sample 100, adjust the confining pressure of the confining pressure cavity and the pore pressure of the void to a preset pressure through the confining pressure system and the gas pore pressure injection system respectively, at which time the pore pressure is the initial pore pressure P2, and record the initial pore pressure P2 through the gas pore pressure pipeline pressure gauge 16; Step 2: Turn on the liquid pore pressure injection pump 14 to pump liquid into the gap to displace the gas in the pores. When liquid flows out of the pore pressure outlet, the liquid pore pressure injection pump 14 records the injected liquid volume, which is the initial pore volume. V y ; Step 3: refill the sample 100 with the same mass of sediment, close the pore pressure outlet valve 7, adjust the confining pressure and pore pressure to the preset pressure, and start hydrate generation in the pores; Step 4: by checking the gas pore pressure line pressure gauge 16, when the pore pressure stops decreasing, hydrate formation is complete and liquid replacement begins; Step 5: Close the gas pore pressure inlet valve 15, open the liquid pore pressure injection pump 14, and increase the pipeline pressure to 0.1-0.3 MPa higher than the initial pore pressure P2 and at least 0.2 MPa lower than the confining pressure to ensure the safety of the flexible sleeve, and then open the liquid pore pressure inlet valve 12; Step 6: Open the pore pressure outlet valve 7 and record the exhaust gas volume through the gas flow meter 9 V 1 and liquid pore pressure injection pump 14 to record the injected liquid volume V 泵 ; Step 7: When liquid flows out of the pore pressure outlet, the pore gas in the sample 100 is completely replaced, and the pore pressure outlet valve 7 is closed and opened; Step 8: Open the pore pressure outlet valve 7 again to reduce the pore pressure to the initial pore pressure P2, and close the pore pressure outlet valve 7; during the pressure reduction process, the mass change of the drying bottle 8 is measured by a balance. According to the mass-volume conversion formula of the liquid, the liquid density is known, and the volume of the liquid discharged during this pressure change can be calculated. The volume of the discharged liquid is the volume of the liquid discharged during the process of restoring the initial pressure. V 排 ; Step 9: Measure the room temperature T1 with a thermometer and record the temperature inside the gas bath thermostat. The temperature inside the gas bath thermostat is the hydrate temperature T2.

[0041] In this embodiment, during the liquid replacement process, since the replacement pressure is higher than the pore pressure, the pore pressure of the sample rises after the replacement. At this time, part of the water will be discharged. The discharged part of the water is filtered by the drying bottle 8 to reduce the pore pressure to the initial pore pressure P2.

[0042] In this embodiment, the pore volume after replacement is V h It can be calculated by two methods, namely water injection method and exhaust method. The calculation formula of the water injection method is as follows:

[0043] in, V h-water Displaced pore volume calculated for injected water V h , V 泵 is the pumping volume of the liquid pore pressure injection pump, V 排 The volume of liquid discharged during the process of restoring the initial pressure; The calculation formula of the exhaust method is as follows: ; ; ; in, P 1 , P 2 are atmospheric pressure and initial pore pressure, respectively.V 1 is the exhaust gas volume, V h-gas Calculate the pore volume for the gas discharged after displacement, T 1 , T 2 are room temperature and hydrate temperature, respectively. Z 1 , Z 2 are the gas compressibility factors at different pressures, n is the amount of gas substance, R is the gas constant.

[0044] Obtained through V h , substituted into the saturation calculation formula of saturated hydrate sediment sample, and the saturation of saturated hydrate sediment sample was calculated.

[0045] In this embodiment, the water injection method and the exhaust method measure different samples, one is a sample with water in the pores, and the other is a sample with gas in the pores. For calculating the saturation of hydrate sediment samples, the two methods correspond to different substances in the pores of the experimental samples. The water injection method corresponds to the saturated sample, and the exhaust method corresponds to the gas-saturated sample. Compared with the traditional method, both methods measure and calculate the saturation of the sample during the experiment, which is impossible for the traditional method.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the saturation of a hydrate sediment sample based on a replacement method, characterized in that: include: A high-pressure reactor, the interior of which is a confining pressure chamber filled with confining pressure liquid; A sample is arranged in the confining pressure chamber, the top of the sample is connected to the top surface of the high-pressure reactor, the bottom of the sample is connected to the bottom surface of the high-pressure reactor, the outer wall of the sample is wrapped in a flexible sleeve, and the flexible sleeve is used to isolate the sample from the confining pressure liquid; the sample has pores; A confining pressure system, comprising a confining pressure pump, wherein the confining pressure pump is connected to the confining pressure chamber through a pipeline; A back pressure system, comprising a back pressure pump and a back pressure valve, wherein the back pressure pump, the back pressure valve and the confining pressure chamber are connected in sequence through pipelines; A measuring system, comprising a pore pressure outlet valve, a gas flow meter and a waste gas recovery bottle connected in sequence, wherein the pore pressure outlet valve is connected to the top of the sample through a pore pressure outlet pipe; The pore pressure system comprises a liquid pore pressure injection system and a gas pore pressure injection system, wherein the liquid pore pressure injection system and the gas pore pressure injection system are connected to the bottom of the sample through a pore pressure inlet pipe.

2. The device for measuring the saturation of a hydrate sediment sample based on the replacement method according to claim 1, characterized in that: A confining pressure valve is arranged between the confining pressure pump and the confining pressure chamber.

3. The device for measuring the saturation of a hydrate sediment sample based on a replacement method according to claim 1, characterized in that: A drying bottle is arranged between the pore pressure outlet valve and the gas flow meter.

4. The device for measuring the saturation of a hydrate sediment sample based on a replacement method according to claim 1, characterized in that: The liquid pore pressure injection system comprises a liquid pore pressure inlet valve, a liquid pore pressure pipeline pressure gauge and a liquid pore pressure injection pump which are connected in sequence, and the liquid pore pressure inlet valve is connected to the pore pressure inlet pipe through a pipeline.

5. The device for measuring the saturation of a hydrate sediment sample based on a replacement method according to claim 1, characterized in that: The gas pore pressure injection system comprises a gas pore pressure inlet valve, a gas pore pressure pipeline pressure gauge, a pressure reducing valve and a high-pressure gas cylinder which are connected in sequence, and the gas pore pressure inlet valve is connected to the pore pressure inlet pipe through a pipeline.

6. The device for measuring the saturation of a hydrate sediment sample based on a replacement method according to claim 1, characterized in that: The high-pressure reactor is placed in an air bath thermostat.

7. A method for measuring and calculating the saturation of a hydrate sediment sample, characterized in that: The device for measuring the saturation of a hydrate sediment sample based on the replacement method according to any one of claims 1 to 6 is completed, comprising the following steps: Obtaining the initial pore volume of hydrate sediment samples V y ; The saturated hydrate sediment samples were obtained by replacement method; Obtaining the replaced pore volume of hydrate sediment samples V h ; The saturation of the hydrate sediment sample is calculated using the following formula: in, S h is the hydrate saturation, V y is the initial pore volume, V h is the pore volume after replacement.

8. The method for measuring and calculating the saturation of a hydrate sediment sample according to claim 7, characterized in that: In obtaining the initial pore volume of the hydrate sediment sample V y In the steps, A set mass of sediment is taken for sampling to obtain a sample, and the confining pressure of the confining pressure cavity and the pore pressure of the gas pore pressure injection system are adjusted to a preset pressure, at which the pore pressure is the initial pore pressure P2; Turn on the liquid pore pressure injection pump to pump liquid to displace pore gas. When liquid flows out of the pore pressure outlet, record the injected liquid volume as the initial pore volume. V y .

9. The method for measuring and calculating the saturation of a hydrate sediment sample according to claim 8, characterized in that: In obtaining the replaced pore volume of hydrate sediment samples V h The steps include: The same mass of sediment is refilled into the sample, the confining pressure and the pore pressure are adjusted to a preset pressure, and hydrate generation begins in the pores; When the pore pressure stops decreasing, hydrate formation is complete and liquid replacement begins; Close the gas pore pressure inlet valve, open the liquid pore pressure injection pump, increase the pipeline pressure to a level higher than the initial pore pressure P2, and then open the liquid pore pressure inlet valve; Record the exhaust gas volume V 1 and injected liquid volume V 泵 ; When liquid flows out of the pore pressure outlet, the pore gas in the sample is completely replaced; Reduce the pore pressure to the initial pore pressure P2, record the volume of gas discharged during the pressure change, and the volume of liquid discharged during the process of restoring the initial pressure. V 排 ; Measuring room temperature T 1 and hydrate temperature T 2.

10. The method for measuring and calculating the saturation of a hydrate sediment sample according to claim 8, characterized in that: Pore ​​volume after replacement V h It can be calculated by two methods, namely water injection method and exhaust method. The calculation formula of the water injection method is as follows: in, V h-water Displaced pore volume calculated for injected water V h , V 泵 is the pumping volume of the liquid pore pressure injection pump, V 排 The volume of liquid discharged during the process of restoring the initial pressure; The calculation formula of the exhaust method is as follows: ； ； ； in, P 1. P 2 are atmospheric pressure and initial pore pressure, V 1 is the exhaust gas volume, V h-gas Calculate the pore volume for the gas discharged after displacement, T 1. T 2 are room temperature and hydrate temperature, respectively. Z 1. Z 2 are the gas compression factors at different pressures, n is the amount of gas substance, R is the gas constant.

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