Natural gas hydrate reservoir productivity measurement system and measurement method

Abstract

The invention discloses a natural gas hydrate reservoir productivity measurement system and a measurement method, 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 the productivity of the hydrate, the invention creates a direct measurement method based on in-situ decomposition, and the method not only has the advantages of simpler operation and data processing, more accurate measurement result and the like, but also adopts the in-situ decomposition method to analyze the saturation of the hydrate. And the method is of great significance to improvement of hydrate reservoir reserve assessment accuracy.

Description

Technical Field

[0001] The invention belongs to the field of reservoir exploration sampling and analysis, relates to a natural gas hydrate sample testing and analysis technology, and in particular to a natural gas hydrate reservoir capacity measurement system and a measurement method. Background Art

[0002] During the exploration and sampling process, the production capacity of the natural gas hydrate reservoir is closely related to the saturation of the reservoir hydrate, and the saturation directly reflects the gas reserves therein. Some of the methods known to the inventor for measuring the production capacity of the exploration reservoir are mainly indirect methods, that is, using acoustic logging, resistivity logging, nuclear magnetic resonance logging, pore water salinity analysis, X-ray computed tomography and other methods to determine the hydrate saturation, and then using the saturation to infer the production capacity. When the indirect method is used to determine the hydrate saturation, it is necessary to comprehensively consider a variety of influencing factors, such as clay content, hydrate occurrence form, etc. The determination process is complicated, the basic parameters for estimation are artificially set, the error is large, and it needs to be further corrected or combined with the direct method for verification, which not only further increases the difficulty of operation and data processing, but also has a long operation cycle and low efficiency. Summary of the invention

[0003] The purpose of the present invention is to provide a new type of natural gas hydrate reservoir capacity measurement system and measurement method, which can perform in-situ decompression decomposition of natural gas hydrate samples and directly measure the total amount of liquid and gas produced during the hydrate decomposition process. Compared with the indirect method for surveying hydrate saturation and capacity, the operation and data processing are simpler, the measurement results are more accurate, and the operation efficiency is higher, which can solve the problems existing in the above-mentioned prior art.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] In one aspect, the present invention provides a natural gas hydrate reservoir productivity measurement system, comprising:

[0006] A hydrate decomposition reactor, used for decomposing a natural gas hydrate sample into liquid and gas, wherein the hydrate decomposition reactor is provided with a pressure regulating unit, and the pressure regulating unit can control the decomposition speed of the natural gas hydrate sample by controlling the pressure in the hydrate decomposition reactor;

[0007] A gas-liquid separator, connected to the hydrate decomposition reactor through a pipeline, and the gas-liquid separator can separate the liquid and gas generated by the hydrate decomposition reactor;

[0008] A liquid storage tank, connected to the liquid outlet of the gas-liquid separator through a pipeline, and used for storing the liquid discharged from the gas-liquid separator;

[0009] A gas storage tank, connected to the gas outlet of the gas-liquid separator through a pipeline, and used for storing the gas discharged from the gas-liquid separator;

[0010] The data measurement system comprises a detection unit 1, a detection unit 2 and a detection unit 3, wherein the detection unit 1 is arranged on the gas-liquid separator and can at least monitor the liquid level, temperature and pressure in the gas-liquid separator, the detection unit 2 is arranged on the liquid storage tank and can at least monitor the liquid level and temperature in the liquid storage tank, and the detection unit 3 is arranged on the gas storage tank and can at least monitor the pressure, temperature and intake flow rate in the gas storage tank;

[0011] The data acquisition and control system is communicatively connected with the detection unit 1, the detection unit 2, the detection unit 3 and the pressure regulating unit.

[0012] Preferably, the pressure regulating unit is a back pressure valve, the back pressure valve is connected to the pipeline between the gas-liquid separator and the hydrate decomposition reactor, and a decomposition product control valve is also connected between the back pressure valve and the hydrate decomposition reactor.

[0013] Preferably, the natural gas hydrate reservoir productivity measurement system further comprises a gas dryer, and the gas dryer is connected to a pipeline between a gas outlet of the gas-liquid separator and the gas storage tank.

[0014] Preferably, the natural gas hydrate reservoir productivity measurement system further comprises a vacuum pumping system, and the vacuum pumping system is used to vacuum the natural gas hydrate reservoir productivity measurement system before testing.

[0015] Preferably, the vacuum pumping system comprises a vacuum pump, and the vacuum pump is connected to the pipeline between the gas dryer and the gas storage tank through a vacuum pump control valve.

[0016] Preferably, the detection unit 1 includes a liquid level transmitter 1, a temperature transmitter 1 and a pressure transmitter 1, and the liquid level transmitter 1, the temperature transmitter 1 and the pressure transmitter 1 are used to monitor the liquid level, temperature and pressure in the gas-liquid separator respectively;

[0017] The second detection unit includes a second liquid level transmitter and a second temperature transmitter, and the second liquid level transmitter and the second temperature transmitter are used to monitor the liquid level height and temperature in the liquid storage tank respectively;

[0018] The detection unit three includes a gas flow meter, a pressure transmitter two and a temperature transmitter three. The pressure transmitter two and the temperature transmitter three are both installed on the gas storage tank. The pressure transmitter two and the temperature transmitter three are used to monitor the pressure and temperature in the gas storage tank respectively. The gas flow meter is connected to the pipeline between the gas dryer and the gas storage tank to monitor the gas flow.

[0019] The liquid level transmitter 1, the temperature transmitter 1, the pressure transmitter 1, the liquid level transmitter 2, the temperature transmitter 2, the gas flow meter, the pressure transmitter 2 and the temperature transmitter 3 are all communicatively connected to the data acquisition and control system.

[0020] Preferably, a gas-water input control valve is further connected between the back pressure valve and the inlet of the gas-liquid separator;

[0021] An exhaust control valve is also connected between the gas dryer and the gas-liquid separator;

[0022] A gas tank control valve is also connected between the gas flow meter and the gas tank;

[0023] A liquid discharge control valve is also connected between the liquid outlet of the gas-liquid separator and the inlet of the liquid storage tank, and a liquid storage tank control valve is also connected between the liquid discharge control valve and the inlet of the liquid storage tank.

[0024] Preferably, the hydrate decomposition reactor is also provided with a safety valve 1 to prevent the hydrate decomposition reactor from being damaged by high pressure;

[0025] The liquid storage tank is also provided with a second safety valve to prevent the liquid storage tank from being damaged by high pressure;

[0026] The gas-liquid separator is also provided with a safety valve 3 to prevent the gas-liquid separator from being damaged by high pressure;

[0027] A safety valve 4 is connected between the gas storage tank control valve and the inlet of the liquid storage tank to prevent the gas storage tank from being damaged by high pressure.

[0028] Preferably, the natural gas hydrate reservoir productivity measurement system further comprises a sampler, wherein the sampler is connected to the hydrate decomposition reactor and is used for providing the natural gas hydrate sample into the hydrate decomposition reactor.

[0029] On the other hand, the present invention provides a method for measuring the productivity of a natural gas hydrate reservoir based on the above-mentioned natural gas hydrate reservoir productivity measurement system, comprising:

[0030] The decomposition product control valve is closed, the hydrate decomposition reactor is filled with water and pressurized to a required pressure value, and the opening pressure value of the back pressure valve is set to be greater than the pressure value of the hydrate decomposition reactor;

[0031] Filling the hydrate decomposition reactor with a natural gas hydrate sample, and opening the decomposition product control valve to control the pressure in the hydrate decomposition reactor through the back pressure valve, so as to decompose the natural gas hydrate sample under reduced pressure;

[0032] After separating the mixture of liquid and gas generated by decomposing the natural gas hydrate sample through the gas-liquid separator, the separated liquid is received through the liquid storage tank, and the separated gas is received through the gas storage tank;

[0033] The data acquisition and control system collects and records the decomposition time and the monitoring value fed back by the data measurement system in real time;

[0034] When the natural gas hydrate sample is completely decomposed, and the liquid storage tank and the gas storage tank have respectively collected the decomposed liquid and gas, the total liquid production and total gas production of the natural gas hydrate sample are calculated based on the monitoring data of the data measurement system and related formulas.

[0035] Compared with the prior art, the present invention has achieved the following technical effects:

[0036] The natural gas hydrate reservoir capacity measurement system proposed in the present invention has a novel and reasonable structure. It first decomposes the natural gas hydrate sample, then separates the gas and liquid of the decomposition products, and respectively collects the separated gas and liquid, and combines the experimental data in the system collected in real time by the data acquisition and control system, so as to directly measure the total amount of liquid and gas generated during the hydrate decomposition process to obtain the natural gas hydrate reservoir capacity. Compared with the indirect method for surveying hydrate saturation and capacity, the present invention has created a direct measurement method based on in-situ decomposition, which not only has the advantages of simpler operation and data processing, more accurate measurement results, and higher operating efficiency, thereby overcoming the shortcomings of the prior art, but also adopts the in-situ decomposition method to analyze hydrate saturation, which is of great significance to improving the accuracy of hydrate reservoir reserve assessment.

[0037] The natural gas hydrate reservoir capacity measurement method proposed in the present invention is implemented based on the above-mentioned natural gas hydrate reservoir capacity measurement system. By first decomposing the natural gas hydrate sample, then separating the decomposition products into gas and liquid, and collecting the separated gas and liquid respectively, combined with the experimental data in the system collected in real time by the data acquisition and control system, the total amount of liquid and gas generated during the hydrate decomposition process can be directly measured to obtain the natural gas hydrate reservoir capacity. Compared with the indirect method for surveying hydrate saturation and capacity, the direct measurement method based on in-situ decomposition of the present invention has the advantages of simpler operation and data processing, more accurate measurement results, higher operating efficiency, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 The figure is a schematic diagram of the overall structure of a natural gas hydrate reservoir productivity measurement system disclosed in an embodiment of the present invention.

[0040] In the figure, the reference numerals are: 100 - natural gas hydrate reservoir productivity measurement system;

[0041] 1-sampler; 2-safety valve 1; 3-hydrate decomposition reactor; 4-decomposition product control valve; 5-back pressure valve; 6-gas-water input control valve; 7-liquid level transmitter 1; 8-temperature transmitter 1; 9-pressure transmitter 1; 10-gas-liquid separator; 11-drainage control valve; 12-liquid storage tank control valve; 13-liquid storage tank; 14-safety valve 2; 15-liquid level transmitter 2; 16-temperature transmitter 2; 17-safety valve 3; 18-exhaust control valve; 19-gas dryer; 20-gas flow meter; 21-gas storage tank control valve; 22-gas storage tank; 23-pressure transmitter 2; 24-temperature transmitter 3; 25-safety valve 4; 26-vacuum pump control valve; 27-vacuum pump; 28-data acquisition and control system. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 creative work are within the scope of protection of the present invention.

[0043] The purpose of the present invention is to provide a new type of natural gas hydrate reservoir capacity measurement system and method, which can perform in-situ decompression decomposition of natural gas hydrate samples and directly measure the total amount of liquid and gas produced during the hydrate decomposition process. Compared with the indirect method for surveying hydrate saturation and capacity, the operation and data processing are simpler, the measurement results are more accurate, and the operation efficiency is higher, which can solve the problems existing in the prior art.

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 1 As shown, this embodiment provides a natural gas hydrate reservoir productivity measurement system 100, which includes a hydrate decomposition reactor 3, a gas-liquid separator 10, a liquid storage tank 13, a gas storage tank 22, a data measurement system and a data acquisition and control system 28, wherein the hydrate decomposition reactor 3 is used to decompose the natural gas hydrate sample into liquid and gas, and the hydrate decomposition reactor 3 is provided with a pressure regulating unit, and the pressure regulating unit can control the pressure in the hydrate decomposition reactor 3, thereby controlling the decomposition rate of the natural gas hydrate sample in the hydrate decomposition reactor 3; the inlet of the gas-liquid separator 10 is connected to the hydrate decomposition reactor 3 through a pipeline to receive the decomposition product from the hydrate decomposition reactor 3, that is, the mixture of liquid and gas produced by the decomposition, and the gas-liquid separator 10 can separate the liquid and gas produced by the decomposition of the hydrate decomposition reactor 3; the liquid storage tank 13 is connected to the gas storage tank 22 through a pipeline. The liquid outlet of the liquid separator 10 is connected to store the liquid separated and discharged in the gas-liquid separator 10, and the gas storage tank 22 is connected to the gas outlet of the gas-liquid separator 10 through a pipeline, and is used to store the gas separated and discharged in the gas-liquid separator 10; the data measurement system includes a detection unit 1, a detection unit 2 and a detection unit 3, wherein the detection unit 1 is configured on the gas-liquid separator 10, and can at least monitor the liquid level, temperature and pressure in the gas-liquid separator 10, the detection unit 2 is configured on the liquid storage tank 13, and can at least monitor the liquid level and temperature in the liquid storage tank 13, and the detection unit 3 is configured on the gas storage tank 22, and can at least monitor the pressure, temperature and intake flow in the gas storage tank 22; the data acquisition and control system 28 is communicatively connected with the aforementioned detection unit 1, detection unit 2, detection unit 3 and pressure regulating unit to collect monitoring data of the detection unit 1, detection unit 2, detection unit 3 and pressure regulating unit. Based on the above monitoring data and corresponding formulas, the total liquid production and total gas production of the natural gas hydrate reservoir can be calculated, thereby completing the measurement of the production capacity of the natural gas hydrate reservoir.

[0046] In practical applications, the hydrate decomposition reactor 3 can store natural gas hydrate samples, and the natural gas hydrate samples in the hydrate decomposition reactor 3 can be smoothly decomposed by controlling the pressure and temperature in the hydrate decomposition reactor 3, thereby generating liquid and gas. Figure 1 As shown, the pressure regulating unit configured on the hydrate decomposition reactor 3 is preferably a back pressure valve 5, which is connected to the pipeline between the gas-liquid separator 10 and the hydrate decomposition reactor 3, and a decomposition product control valve 4 is also connected between the back pressure valve 5 and the hydrate decomposition reactor 3, and the decomposition product control valve 4 is used to control the outflow rate of the gas and liquid generated by the decomposition of the hydrate sample; the back pressure valve 5 can control the pressure in the hydrate decomposition reactor 3, thereby controlling the decomposition rate of the natural gas hydrate sample therein. The decomposition product control valve 4 and the back pressure valve 5 can both be connected to the data acquisition and control system 28 for communication, so as to control the operation of the decomposition product control valve 4 and the back pressure valve 5 (including but not limited to the control valve opening and closing and valve opening) through the data acquisition and control system 28.

[0047] In some embodiments, Figure 1 As shown, a gas-water input control valve 6 is also connected between the back pressure valve 5 and the inlet of the gas-liquid separator 10. The gas-water input control valve 6 is installed at the inlet of the gas-liquid separator 10 to control the speed at which the liquid and gas mixture flows into the gas-liquid separator 10. The gas-water input control valve 6 can be communicatively connected with the data acquisition and control system 28 to control the operation of the gas-water input control valve 6 (including but not limited to control valve opening and closing and valve opening) through the data acquisition and control system 28.

[0048] In some embodiments, Figure 1 As shown, the natural gas hydrate reservoir productivity measurement system 100 is also connected to a gas dryer 19 on the pipeline between the gas outlet of the gas-liquid separator 10 and the gas storage tank 22. The gas dryer 19 is connected to the gas-liquid separator 10 through the exhaust control valve 18, and the exhaust control valve 18 is installed on the top of the gas-liquid separator 10 to control the speed of gas discharge therein. The gas dryer 19 is used to dry the gas discharged from the gas-liquid separator 10 and then discharge it into the gas storage tank 22. The exhaust control valve 18 can be connected to the data acquisition and control system 28 for communication, so as to control the operation of the exhaust control valve 18 (including but not limited to the control valve opening and closing and valve opening) through the data acquisition and control system 28.

[0049] In some embodiments, Figure 1As shown, the natural gas hydrate reservoir productivity measurement system 100 is also equipped with a vacuum system; the vacuum system is connected to the entire system, and is used to vacuum the entire system before the natural gas hydrate sample decomposes, so as to avoid the interference of the air retained in the system on the measurement result, and make the measurement result more accurate. Among them, the vacuum system preferably uses a vacuum pump 27, and the vacuum pump 27 is connected to the pipeline between the gas dryer 19 and the gas storage tank 22 through the vacuum pump control valve 26. The vacuum pump control valve 26 is installed at the inlet of the vacuum pump 27, and is used to control the connection or disconnection of the vacuum pump 27 with the entire measurement system. The data acquisition and control system 28 is connected to the vacuum pump 27 and the vacuum pump control valve 26 in communication to control the operation of the vacuum pump 27 and the vacuum pump control valve 26 (including but not limited to controlling the opening and closing of the vacuum pump 27 and the vacuum pump control valve 26).

[0050] In some embodiments, Figure 1 As shown, the detection unit 1 includes a liquid level transmitter 7, a temperature transmitter 8 and a pressure transmitter 9, which are all installed on the gas-liquid separator 10 and are respectively used to monitor and display the liquid level, temperature and pressure in the gas-liquid separator 10 in real time. The liquid level transmitter 7, the temperature transmitter 8 and the pressure transmitter 9 are all connected to the data acquisition and control system 28 for communication.

[0051] In some embodiments, Figure 1 As shown, the detection unit 2 includes a liquid level transmitter 2 15 and a temperature transmitter 2 16, both of which are installed on the liquid storage tank 13, and the liquid level transmitter 2 15 is used to monitor and display the liquid level in the liquid storage tank 13 in real time, and the temperature transmitter 2 16 is used to monitor and display the temperature in the liquid storage tank 13 in real time. The liquid level transmitter 2 15 and the temperature transmitter 2 16 are both connected to the data acquisition and control system 28 for communication.

[0052] In some embodiments, Figure 1 As shown, the detection unit three includes a gas flow meter 20, a pressure transmitter two 23 and a temperature transmitter three 24. The pressure transmitter two 23 and the temperature transmitter three 24 are both installed on the gas tank 22. The pressure transmitter two 23 is used to monitor and display the pressure in the gas tank 22 in real time, and the temperature transmitter three 24 is used to monitor and display the temperature in the gas tank 22 in real time. The gas flow meter 20 is connected to the pipeline between the gas dryer 19 and the gas tank 22, and is close to the outlet of the gas dryer 19, for monitoring the gas flow. The gas flow meter 20, the pressure transmitter two 23 and the temperature transmitter three 24 are all communicatively connected to the data acquisition and control system 28. Based on the above-mentioned setting of the detection unit three, it is preferred that the vacuum pump 27 is connected to the pipeline between the gas flow meter 20 and the gas dryer 19 through the vacuum pump control valve 26, as shown in FIG. Figure 1 shown.

[0053] In some embodiments, Figure 1 As shown, a gas tank control valve 21 is also connected between the gas flow meter 20 and the gas tank 22. The gas tank control valve 21 is installed at the inlet of the gas tank 22 and is used to control the opening and closing of the gas tank 22; the data acquisition and control system 28 is communicated with the gas tank control valve 21 to control the operation of the gas tank control valve 21 (including but not limited to the opening and closing of the control valve and the valve opening).

[0054] In some embodiments, when the natural gas hydrate reservoir productivity measurement system 100 is in use, a sample supply device may be connected to the hydrate decomposition reactor 3, or a sampler 1 may be directly configured in the system. In this embodiment, the natural gas hydrate reservoir productivity measurement system 100 is preferably directly configured with a sampler 1, and the sampler 1 is connected to the inlet of the hydrate decomposition reactor 3 to provide the natural gas hydrate sample required for system testing into the hydrate decomposition reactor 3. The sampler 1 preferably adopts a pressure-maintaining sampler.

[0055] In some embodiments, in order to make the natural gas hydrate reservoir productivity measurement system 100 operate more reliably and efficiently, a safety valve 12, a discharge control valve 11, a liquid storage tank control valve 12, a safety valve 2 14, a safety valve 3 17 and a safety valve 4 25 are also configured in the system. Among them: the safety valve 12 is installed on the hydrate decomposition reactor 3. When the pressure in the hydrate decomposition reactor 3 exceeds the set value, the pressure can be quickly released through the safety valve 2, thereby preventing the system from being damaged by excessive pressure; the discharge control valve 11 is installed at the liquid outlet of the gas-liquid separator 10, and is used to control the outflow rate of the liquid therein; the liquid storage tank control valve 12 is installed at the inlet of the liquid storage tank 13, and is located between the discharge control valve 11 and the inlet of the liquid storage tank 13. The liquid storage tank control valve 12 is used to control the opening and closing of the liquid storage tank 13; the safety valve 2 14 is installed at the bottom of the liquid storage tank 13, and is used to control the opening and closing of the liquid storage tank 13. When the pressure in the liquid storage tank 13 exceeds the set value, it is used to quickly release the pressure to prevent the liquid storage tank 13 from being damaged by the high pressure; the safety valve three 17 is installed on the gas-liquid separator 10, and is used to quickly release the pressure when the pressure in the gas-liquid separator 10 exceeds the set value, so as to prevent the gas-liquid separator 10 from being damaged by the high pressure. The safety valve three 17 is preferably connected between the exhaust control valve 18 and the air outlet of the gas-liquid separator 10; the safety valve four 25 is connected between the gas tank control valve 21 and the inlet of the liquid storage tank 13, and is used to quickly release the pressure when the pressure in the gas tank 22 exceeds the set value, so as to prevent the gas tank 22 from being damaged by the high pressure.

[0056] In some embodiments, in order to make the natural gas hydrate reservoir productivity measurement system 100 operate more reliably and efficiently, it is preferred that any pipeline connecting two components in the entire system preferably adopts a high-pressure pipeline, including but not limited to the pipeline between the hydrate decomposition reactor 3 and the back pressure valve 5, the pipeline between the back pressure valve 5 and the gas-liquid separator 10, the pipeline between the gas-liquid separator 10 and the gas dryer 19, the pipeline between the gas dryer 19 and the vacuum pump 27, the pipeline between the gas dryer 19 and the gas flow meter 20, the pipeline between the gas flow meter 20 and the gas storage tank 22, the pipeline between the gas-liquid separator 10 and the liquid storage tank 13, etc.

[0057] In the above-mentioned natural gas hydrate reservoir productivity measurement system 100, the data acquisition and control system 28 can control the working status of the back pressure valve 5 and the vacuum pump 27, and collect data from the liquid level transmitter 1 7, the temperature transmitter 1 8, the pressure transmitter 1 9, the liquid level transmitter 2 15, the temperature transmitter 2 16, the gas flow meter 20, the pressure transmitter 2 23 and the temperature transmitter 3 24. In order to more intuitively represent the function of the data acquisition and control system 28 in the measurement system, Figure 1 The detection points 1 to 6 and the control points 1 and 2 are marked as partitions, and the detection points 1 to 6, the control points 1 and the control points 2 are all the functional scope of the data acquisition and control system 28. If the data acquisition and control system 28 uses a controller with a display screen, it can also display the real-time collected data on the display screen in real time. The working process and working principle of the natural gas hydrate reservoir productivity measurement system 100 in this embodiment are specifically described below:

[0058] First, the vacuum pump 27 is turned on, and all valves in the system are opened to evacuate the hydrate decomposition reactor 3, the gas-liquid separator 10, the liquid storage tank 13, the gas storage tank 22, and all high-pressure pipelines and valves in the connecting system through the vacuum pump 27. The vacuum pump 27 is then turned off.

[0059] After that, the test is started. Close the decomposition product control valve 4, use the booster system to fill the hydrate decomposition reactor 3 with water and pressurize it to the required pressure value, set the opening pressure value of the back pressure valve 5 to be greater than the pressure value of the hydrate decomposition reactor 3, and ensure that the hydrate decomposition reactor 3 will not be opened before the natural gas hydrate sample starts to decompose; transfer the natural gas hydrate sample from the sampler 1 to the hydrate decomposition reactor 3 under pressure; slowly open the decomposition product control valve 4, and slowly control the pressure in the hydrate decomposition reactor 3 through the back pressure valve 5, and the natural gas hydrate sample begins to decompress (depressurize) and decompose; the mixture of liquid and gas produced by the decomposition of the natural gas hydrate sample enters the gas-liquid separator 10 through the gas-water input control valve 6, and after the gas-liquid separator 10 separates the decomposition product into gas and liquid, the separated liquid enters the liquid storage tank 13 downward by gravity, and the separated gas passes through the gas dryer 19 and the gas flowmeter 20 in turn and enters the gas storage tank 22. In the above-mentioned sample decomposition and gas-liquid separation process, the data acquisition and control system 28 collects and records the decomposition time and the monitoring values ​​fed back by the liquid level transmitter 1 7, temperature transmitter 1 8, pressure transmitter 1 9, liquid level transmitter 2 15, temperature transmitter 2 16, gas flow meter 20, pressure transmitter 2 23 and temperature transmitter 3 24 in real time; when the pressure in the hydrate decomposition reactor 3 drops to the specified value and the pressure no longer changes significantly, it means that the natural gas hydrate sample therein is decomposed; when the liquid and gas produced by the decomposition of the natural gas hydrate sample are collected, the liquid storage tank control valve 12 and the gas storage tank control valve 21 are closed; the total liquid production and the total gas production are calculated by the monitoring data of the liquid level transmitter 1 7, temperature transmitter 1 8, pressure transmitter 1 9, liquid level transmitter 2 15, temperature transmitter 2 16, gas flow meter 20, pressure transmitter 2 23 and temperature transmitter 3 24 and the corresponding formula. It should be noted that the formulas used for calculation are common knowledge in the field and will not be repeated here.

[0060] In summary, the natural gas hydrate reservoir capacity measurement system and measurement method proposed in this scheme introduces a direct measurement method, which first decomposes the natural gas hydrate sample quantitatively under reduced pressure, separates the gas and liquid of the decomposition product, and then collects the decomposed gas and liquid respectively, so as to directly measure the total amount of liquid and gas produced during the hydrate decomposition process to obtain the capacity of the natural gas hydrate reservoir. Compared with the indirect method for surveying hydrate saturation and capacity, the direct measurement method of this scheme has the advantages of simpler operation and data processing, and more accurate measurement results. This scheme directly configures the hydrate decomposition reactor 3 in the measurement system, and uses the in-situ decomposition method to analyze the hydrate saturation, which is of great significance to the improvement of the accuracy of hydrate reservoir reserve assessment.

[0061] It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0062] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A natural gas hydrate reservoir productivity measurement system, characterized in that: include: A hydrate decomposition reactor (3) is used to decompose the natural gas hydrate sample into liquid and gas, and the hydrate decomposition reactor (3) is provided with a pressure regulating unit, and the pressure regulating unit can control the decomposition speed of the natural gas hydrate sample by controlling the pressure in the hydrate decomposition reactor (3); A gas-liquid separator (10) is connected to the hydrate decomposition reactor (3) via a pipeline, and the gas-liquid separator (10) is capable of separating liquid and gas generated by decomposition of the hydrate decomposition reactor (3); A liquid storage tank (13), connected to the liquid outlet of the gas-liquid separator (10) through a pipeline, and used for storing liquid discharged from the gas-liquid separator (10); A gas storage tank (22), connected to the gas outlet of the gas-liquid separator (10) through a pipeline, and used for storing the gas discharged from the gas-liquid separator (10); A data measurement system, comprising a detection unit 1, a detection unit 2 and a detection unit 3, wherein the detection unit 1 is arranged on the gas-liquid separator (10) and is capable of at least monitoring the liquid level, temperature and pressure in the gas-liquid separator (10), the detection unit 2 is arranged on the liquid storage tank (13) and is capable of at least monitoring the liquid level and temperature in the liquid storage tank (13), and the detection unit 3 is arranged on the gas storage tank (22) and is capable of at least monitoring the pressure, temperature and intake flow rate in the gas storage tank (22); A data acquisition and control system (28) is communicatively connected with the detection unit 1, the detection unit 2, the detection unit 3 and the pressure regulating unit.

2. The natural gas hydrate reservoir productivity measurement system according to claim 1, characterized in that: The pressure regulating unit is a back pressure valve (5), and the back pressure valve (5) is connected to the pipeline between the gas-liquid separator (10) and the hydrate decomposition reactor (3), and a decomposition product control valve (4) is also connected between the back pressure valve (5) and the hydrate decomposition reactor (3).

3. The natural gas hydrate reservoir productivity measurement system according to claim 2, characterized in that: It also includes a gas dryer (19), which is connected to the pipeline between the gas outlet of the gas-liquid separator (10) and the gas storage tank (22).

4. The natural gas hydrate reservoir productivity measurement system according to claim 3, characterized in that: It also comprises a vacuum pumping system, wherein the vacuum pumping system is used to vacuum the natural gas hydrate reservoir productivity measurement system (100) before testing.

5. The natural gas hydrate reservoir productivity measurement system according to claim 4, characterized in that: The vacuum pumping system comprises a vacuum pump (27), and the vacuum pump (27) is connected to the pipeline between the gas dryer (19) and the gas storage tank (22) through a vacuum pump control valve (26).

6. The natural gas hydrate reservoir productivity measurement system according to claim 3, characterized in that: The detection unit 1 comprises a liquid level transmitter 1 (7), a temperature transmitter 1 (8) and a pressure transmitter 1 (9), wherein the liquid level transmitter 1 (7), the temperature transmitter 1 (8) and the pressure transmitter 1 (9) are used to monitor the liquid level, temperature and pressure in the gas-liquid separator (10) respectively; The second detection unit comprises a second liquid level transmitter (15) and a second temperature transmitter (16), wherein the second liquid level transmitter (15) and the second temperature transmitter (16) are used to monitor the liquid level and temperature in the liquid storage tank (13) respectively; The detection unit three comprises a gas flow meter (20), a pressure transmitter two (23) and a temperature transmitter three (24); the pressure transmitter two (23) and the temperature transmitter three (24) are both installed on the gas storage tank (22); the pressure transmitter two (23) and the temperature transmitter three (24) are respectively used to monitor the pressure and temperature in the gas storage tank (22); the gas flow meter (20) is connected to the pipeline between the gas dryer (19) and the gas storage tank (22) to monitor the gas flow; The liquid level transmitter 1 (7), the temperature transmitter 1 (8), the pressure transmitter 1 (9), the liquid level transmitter 2 (15), the temperature transmitter 2 (16), the gas flow meter (20), the pressure transmitter 2 (23) and the temperature transmitter 3 (24) are all connected to the data acquisition and control system (28) for communication.

7. The natural gas hydrate reservoir productivity measurement system according to claim 3, characterized in that: A gas-water input control valve (6) is also connected between the back pressure valve (5) and the inlet of the gas-liquid separator (10); An exhaust control valve (18) is also connected between the gas dryer (19) and the gas-liquid separator (10); A gas tank control valve (21) is also connected between the gas flow meter (20) and the gas tank (22); A liquid discharge control valve (11) is connected between the liquid outlet of the gas-liquid separator (10) and the inlet of the liquid storage tank (13), and a liquid storage tank control valve (12) is connected between the liquid discharge control valve (11) and the inlet of the liquid storage tank (13).

8. The natural gas hydrate reservoir productivity measurement system according to claim 3, characterized in that: The hydrate decomposition reactor (3) is also provided with a safety valve 1 (2) for preventing the hydrate decomposition reactor (3) from being damaged by high pressure; The liquid storage tank (13) is also provided with a second safety valve (14) for preventing the liquid storage tank (13) from being damaged by high pressure; The gas-liquid separator (10) is also provided with a safety valve three (17) for preventing the gas-liquid separator (10) from being damaged by high pressure; A safety valve 4 (25) is connected between the gas storage tank control valve (21) and the inlet of the liquid storage tank (13) to prevent the gas storage tank (22) from being damaged by high pressure.

9. The natural gas hydrate reservoir productivity measurement system according to any one of claims 1 to 8, characterized in that: It also comprises a sampler (1), wherein the sampler (1) is connected to the hydrate decomposition reactor (3) and is used to provide the natural gas hydrate sample into the hydrate decomposition reactor (3).

10. A method for measuring the productivity of a natural gas hydrate reservoir implemented based on the natural gas hydrate reservoir productivity measurement system according to any one of claims 2 to 8, characterized in that: include: The decomposition product control valve (4) is closed, the hydrate decomposition reactor (3) is filled with water and pressurized to a required pressure value, and the opening pressure value of the back pressure valve (5) is set to be greater than the pressure value of the hydrate decomposition reactor (3); Filling the hydrate decomposition reactor (3) with a natural gas hydrate sample, and opening the decomposition product control valve (4) to control the pressure in the hydrate decomposition reactor (3) through the back pressure valve (5) to decompress the natural gas hydrate sample; After separating the mixture of liquid and gas generated by decomposing the natural gas hydrate sample through the gas-liquid separator (10), the separated liquid is received through the liquid storage tank (13), and the separated gas is received through the gas storage tank (22); The decomposition time and the monitoring value fed back by the data measurement system are collected and recorded in real time by the data collection and control system (28); When the natural gas hydrate sample is completely decomposed, and the liquid storage tank (13) and the gas storage tank (22) have respectively collected the decomposed liquid and gas, the total liquid production and total gas production of the natural gas hydrate sample are calculated based on the monitoring data of the data measurement system and related formulas.

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