A device and method for preparing gas hydrate and in-situ detection of its physical property parameters

Abstract

The present invention provides a device and method for preparing gas hydrates and in-situ detection of their physical parameters. The device includes a gas hydrate preparation unit, a pressure regulating unit, a filtering unit, and a physical parameter detection unit; the gas hydrate preparation unit has N interconnected pipe sections in the height direction, N ≥ 2; the gas hydrate preparation unit is provided with an input port and an output port for materials, and the input port and the output port are connected to the cavity of the gas hydrate preparation unit; the pressure regulating unit is connected to the gas hydrate preparation unit, the physical parameter detection unit is arranged on the peripheral wall or bottom wall of the gas hydrate preparation unit, and the filtering unit is at least partially located at the output port. The device has a simple structure and can realize accurate measurement of the physical parameters of pure gas hydrates and hydrate-containing sediments. It is expected to be used as an important detection equipment in related fields such as natural gas hydrate exploration and development and oil and gas pipeline hydrate prevention and control.

Description

Technical Field

[0001] The invention belongs to the field of natural gas hydrate exploration, development and related application technology, and relates to a device and method for preparing gas hydrate and in-situ detecting of its physical property parameters. Background Art

[0002] Natural gas hydrate is an ice-like solid crystalline compound formed by natural gas molecules and water molecules under low temperature and high pressure. It can ignite in the air and is commonly known as combustible ice. According to preliminary estimates, the carbon equivalent of natural gas hydrates in the world is twice that of all conventional fossil energy (coal, oil, and natural gas), with a total resource volume of 2×10 16 m 3 CH4(STP).

[0003] In view of the important economic value of natural gas hydrates, many countries in the world have included the development of natural gas hydrates in their national key development strategies. China, the United States, Japan, Canada, the United Kingdom and other countries have successively invested in the investigation of combustible ice resources and the research of mining technology. The natural gas hydrate reservoir is a more complex system than conventional oil and gas layers. To utilize natural gas hydrate resources, it is necessary to fully understand the characteristics of the hydrate reservoir. The primary scientific issue is the interaction between hydrates and hydrate reservoirs, that is, the influence of sediment characteristics on hydrate formation, distribution and pore fluid flow. This has important guiding significance for the exploration of natural gas hydrates, reserve estimation and the formulation of mining methods.

[0004] The exploration method of natural gas hydrate mainly determines the distribution location of hydrate by observing abnormal characteristics and signs obtained by logging. The most commonly used geophysical detection methods are resistivity logging and seismic methods. Since hydrates have a salt exclusion effect, pure hydrates have a higher resistivity. From the resistivity logging curve, it can be seen that the resistivity of the natural gas hydrate-containing area is significantly greater than that of the water-saturated area. The seismic method identifies hydrates, infers the location of hydrate reservoirs, and predicts hydrate saturation based on the difference in acoustic wave velocity between hydrate-containing reservoirs and their adjacent sedimentary layers. Compared with other porous fluids, pure hydrates have higher compression wave velocities Vp and shear wave velocities Vs, which leads to a corresponding increase in the measured wave velocity of the hydrate-containing reservoir, thereby determining the location of natural gas hydrates.

[0005] The development of natural gas hydrates is to destroy the thermodynamic stability of hydrates in the reservoir by reducing pressure, injecting heat, injecting chemicals, etc., so that they decompose into natural gas and water, and then use methods similar to conventional natural gas extraction to extract the released natural gas to the ground. The hydrate decomposition process is a phase change process, from solid hydrates to gas and water. This process absorbs a lot of heat, causing the reservoir temperature to drop. In order to enhance the decomposition process of natural gas hydrates, it is necessary to study the heat transfer law of gas-liquid-solid in the pore flow process.

[0006] To this end, domestic and foreign research institutions have designed and built a series of devices to measure the apparent resistivity, acoustic wave velocity and total heat transfer coefficient of hydrate-containing sediments. However, the apparent physical property parameters are not only related to the operating conditions (temperature, pressure, axial stress, etc.), but also to the type of sediment, the shape and distribution of hydrates, resulting in the lack of universality of the measured apparent physical property parameters and the large prediction error of the established inversion model equation. In order to facilitate practical applications, the prediction equations and inversion models established are often required to have a wider range of applicability and good universality. In heat transfer, the total heat transfer coefficient of the fluid changes with the operating conditions, but the intrinsic thermal conductivity of the fluid is determined. Based on the intrinsic thermal conductivity of the fluid inside and outside the tube, the thermal resistance of the tube wall and the thermal resistance of the dirt, the total heat transfer coefficient equation can be established, and the equation has high universality. According to the above modeling ideas, analyzing the composition and content of hydrate-containing sediments, and establishing the apparent physical property parameter equation based on the content and the intrinsic physical property parameters of each component is the optimal solution to the above problems. Therefore, the key issue is how to measure the physical properties of pure hydrates, such as thermal conductivity, resistivity and acoustic wave velocity. This is not only to supplement the basic physical parameters at the scientific level, but also an important basis for natural gas hydrate exploration, development and gas hydrate application technology. Summary of the invention

[0007] The present invention provides a device for preparing gas hydrates and in-situ detection of their physical property parameters. The device has a simple structure and can accurately measure the physical property parameters of pure gas hydrates, providing important basic data for related technical fields such as natural gas hydrate exploration and development and hydrate prevention and control of oil and gas pipelines.

[0008] The present invention also provides a method for preparing gas hydrates and in-situ detection of their physical parameters, which integrates gas hydrate preparation, liquid and gas drainage, solid hydrate extrusion molding, and in-situ measurement, and can accurately measure the physical parameters of pure gas hydrates.

[0009] The present invention provides a device for preparing gas hydrates and in-situ detection of their physical property parameters, the device comprising a gas hydrate preparation unit, a filtering unit, a pressure regulating unit, and a physical property parameter detection unit; the gas hydrate preparation unit has N interconnected pipe sections in the height direction, N ≥ 2; the gas hydrate preparation unit is provided with an input port and an output port for materials, and the input port and the output port are connected to the cavity of the gas hydrate preparation unit;

[0010] The pressure regulating unit is connected to the gas hydrate preparation unit, the physical property parameter detection unit is arranged on the peripheral wall or the bottom wall of the gas hydrate preparation unit, and the filtering unit is at least partially located at the output port.

[0011] In the device as described above, the gas hydrate preparation unit is a cylindrical autoclave, and the height-to-diameter ratio of the autoclave is greater than 10:1.

[0012] The device as described above, wherein in the height direction, the gas hydrate production unit comprises a first pipe section and a second pipe section in order from top to bottom;

[0013] The material of the first pipe section is metal material;

[0014] The second pipe section is made of metal or visible material.

[0015] In the device as described above, the physical property parameter detection unit includes at least one of a thermal conductivity detection unit, a sound wave velocity detection unit, and a resistivity detection unit.

[0016] The device as described above, wherein the pressure regulating unit includes a movable piston, the movable piston is placed in the cavity of the gas hydrate unit, and the movable piston divides the cavity into a reaction chamber and a pressure regulating chamber, and the pressure regulating chamber is located at the upper part of the reaction chamber.

[0017] In the device as described above, the filter unit is arranged on the inner wall of the output port, and the filter unit is selected from a filter mesh or a metal filter sintered plate.

[0018] The device as described above, wherein the filter pore diameter of the filter unit is less than 10 μm.

[0019] The present invention also provides a method for preparing gas hydrates and in-situ detection of their physical property parameters. The method uses the above-mentioned device to prepare gas hydrates and in-situ detection of their physical property parameters, and comprises the following steps:

[0020] 1) The raw materials enter the cavity of the gas hydrate preparation unit through the input port;

[0021] 2) adjusting the pressure in the cavity by controlling a pressure regulating unit to prepare gas hydrates;

[0022] 3) controlling the pressure regulating unit to filter the reaction system in the cavity through the filtering unit to filter the gas hydrate and the gas-liquid phase, so that the filtered gas-liquid phase is discharged from the gas hydrate preparation unit through the output port;

[0023] 4) Detecting the physical property parameters of the gas hydrate by a physical property parameter detection unit.

[0024] The method as described above, wherein after step 3), further comprises: compressing the gas hydrate by controlling a pressure regulating unit.

[0025] The method as described above, wherein the gas hydrate comprises pure gas hydrate and a sediment containing gas hydrate.

[0026] The implementation of the present invention has at least the following advantages:

[0027] 1) The device and method for preparing gas hydrates and in-situ detection of their physical property parameters provided by the present invention integrate the preparation of gas hydrates, gas-liquid-solid separation, solid hydrate extrusion molding, and in-situ measurement. It can not only provide important basic physical property parameters, but also provide a basis for establishing prediction models such as acoustic wave velocity, heat transfer rate, resistivity, etc. of complex systems.

[0028] 2) The most outstanding advantage of the device for preparing gas hydrates and in-situ detection of their physical properties provided by the present invention is that it is composed of N (N≥2) interconnected pipe sections, which can not only increase the axial height, but also increase the volume of the gas hydrate preparation unit, thereby realizing large-scale preparation of gas hydrates. A sufficient amount of gas hydrate samples is a necessary prerequisite for the determination of the physical properties of pure gas hydrates. At the same time, the physical property detection unit can be arranged on the pipe wall or the bottom of the kettle body. The design of multiple pipe sections is conducive to structural design and replacement according to the characteristics of different physical property inspection units, ensuring the flexibility of operation and design, and guaranteeing the accurate measurement of physical properties such as acoustic wave velocity, heat transfer rate, and resistivity.

[0029] 3) The device for preparing gas hydrates and detecting their physical properties in situ provided by the present invention can simulate the pressure acting on gas hydrates by changing the axial stress through a pressure regulating unit, and simulate the influence of reservoir depth on the physical properties of gas hydrates.

[0030] 4) The device and method for preparing gas hydrates and in-situ detection of their physical parameters provided by the present invention have high universality and are applicable to pure gas hydrates, hydrate sediments, and hydrate-gas-liquid mixtures. The device and method provided by the present invention can be widely used in the fields of natural gas hydrate resource exploration, development, oil and gas pipeline transportation, and hydrate-based application technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of a device for preparing gas hydrates and in-situ detection of their physical property parameters according to an embodiment of the present invention.

[0032] Description of reference numerals:

[0033] 1: Gas hydrate preparation unit;

[0034] 2: Filter unit;

[0035] 3: Pressure regulating unit;

[0036] 4: Physical parameter detection unit;

[0037] 5: Pressurized fluid input port;

[0038] 6: Input and output ports for raw liquid and raw gas;

[0039] 7: The first pipe section;

[0040] 8: The second pipe section;

[0041] 9: reaction chamber;

[0042] 10: Pressure regulating chamber. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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.

[0044] The first aspect of the present invention provides a device for preparing gas hydrates and in-situ detecting physical parameters thereof. Figure 1 FIG. 1 is a schematic diagram of a device structure for preparing gas hydrates and detecting their physical parameters in situ according to an embodiment of the present invention. Figure 1 As shown, the device includes a gas hydrate preparation unit 1, a filtering unit 2, a pressure regulating unit 3, and a physical property parameter detection unit 4; the gas hydrate preparation unit 1 is adjustable in the height direction and is composed of N interconnected pipe sections, N ≥ 2. Among them, the gas hydrate preparation unit 1 is provided with an input port and an output port for materials, and the input port and the output port are connected to the cavity of the gas hydrate preparation unit 1, the pressure regulating unit 3 is also connected to the gas hydrate preparation unit 1, the physical property parameter detection unit 4 is arranged on the peripheral wall or bottom wall of the gas hydrate preparation unit 1, and the filtering unit 2 is at least partially located at the output port.

[0045] The gas hydrate preparation unit 1 of the present invention is used to prepare gas hydrates, and the gas hydrate preparation unit 1 has a cavity, which is used to provide a reaction place for the raw materials for preparing gas hydrates. Specifically, the gas hydrate preparation unit 1 also has an input port and an output port for the raw materials. In one embodiment, the raw materials for preparing gas hydrates include methane gas and water. At this time, two raw material input ports can be set, one input port is used to input methane gas into the cavity, and the other input port is used to input water into the cavity. Alternatively, one input port can be set, and methane gas and water are fed into the same input port through a liquid inlet pipeline and an air inlet pipeline, respectively. In addition, the gas hydrate preparation unit 1 also has an output port for discharging excess raw materials.

[0046] The present invention can also integrate the input and output ports of the raw material liquid and raw material gas into one port, that is, the input and output of the raw materials are completed at different times through the same opening, so as to make the device structure simpler and improve safety. Figure 1 As shown, in a specific embodiment, the raw materials for preparing gas hydrates share the input and output ports 6 for the raw material liquid and the raw material gas. When feeding, the port 6 is the input port; when reacting, the port 6 is in a closed state; when the reaction is completed and the excess raw materials need to be discharged, the port 6 is the output port and is in an open state. Specifically, the closed and open states of the port 6 can be controlled by a valve.

[0047] In a specific embodiment, the input and output ports 6 of the raw material liquid and the raw material gas are connected to the raw material gas cylinder and the raw material liquid storage tank outside the gas hydrate preparation unit 1 through the gas inlet pipe and the liquid inlet pipe, respectively. Specifically, the raw material gas in the raw material gas cylinder and the raw material liquid in the raw material liquid storage tank both enter the cavity of the gas hydrate preparation unit 1 through the input and output ports 6 of the raw material liquid and the raw material gas, thereby realizing the transportation of the raw materials to the gas hydrate preparation unit 1 to complete the preparation of hydrates.

[0048] On the air inlet pipe and the liquid inlet pipe, the valve and the drive unit can be connected to realize the efficient and controllable delivery of the raw gas and the raw liquid to the cavity. Among them, the drive unit can be a hand pump or a constant speed and constant pressure pump.

[0049] A pressure probe may also be provided on the raw material input pipeline to detect the current pressure in the pipeline in real time.

[0050] The filtering unit 2 of the present invention is located inside the gas hydrate preparation unit 1, and is mainly used to discharge the residual raw gas and raw liquid out of the cavity after the reaction is completed, and to retain the prepared solid gas hydrate in the cavity. Specifically, a raw material output pipeline is also provided outside the gas hydrate preparation unit 1, one end of the raw material output pipeline is connected to the input and output ports 6 of the raw material liquid and raw material gas, and the other end is an exhaust and liquid discharge port, and the excess raw gas and raw liquid in the cavity can be discharged from the raw material output pipeline.

[0051] The present invention does not limit the number and location of the filter units 2, as long as at least part of the filter units 2 are located at the output port. In the specific operation process, one or more filter units 2 can be selected according to the difficulty of separation.

[0052] The gas hydrate preparation unit 1 of the present invention is also connected to a pressure regulating unit 3, which is located inside the cavity of the gas hydrate preparation unit 1. The pressure regulating unit 3 is used to control the pressure in the cavity of the gas hydrate preparation unit 1. During the preparation of gas hydrates, the pressure regulating unit 3 can provide a suitable pressure to achieve the formation conditions of gas hydrates; during the separation of gas hydrates from other excess raw materials, the pressure regulating unit 3 can provide a suitable driving force and constant pressure conditions for the separation process to prevent the decomposition of hydrates. Specifically, pressure can be provided for the preparation of gas hydrates by injecting pressurized liquid into the cavity of the gas hydrate preparation unit 1. Figure 1 As shown, a pressurized liquid inlet 5 is provided at the top of the device, and the pressurized liquid can enter the cavity of the gas hydrate preparation unit 1 through the pressurized liquid inlet 5 from the liquid inlet pipeline outside the device, and the reaction pressure is regulated by squeezing and pushing the piston up and down.

[0053] A physical property parameter detection unit 4 is also provided on the peripheral wall or bottom wall of the hydrate preparation unit 1. The physical property parameter detection unit 4 is used to measure the physical property parameters of the gas hydrate. The present invention does not limit the arrangement form of the physical property parameter detection unit, which can be arranged on the peripheral wall or bottom wall, and can be used alone or in combination with multiple detection means.

[0054] In a specific embodiment, the process steps for preparing gas hydrates and in-situ detection of their physical properties of the present invention include: the reaction raw materials enter the cavity of the gas hydrate preparation unit 1 from the input and output ports 6 of the raw material liquid and the raw material gas, and then the pressurized liquid is passed from the pressurized liquid input port 5 into the upper half of the cavity of the gas hydrate preparation unit 1, and the cavity pressure is controlled by squeezing the pressure regulating unit 3. When the pressure of the cavity reaches the set hydration reaction conditions, the synthesis amount of the gas hydrate is judged by the position of the pressure regulating unit 3. When a sufficient amount of gas hydrate is prepared, Afterwards, the input and output ports 6 of the raw liquid and raw gas are set to an open state, and the pressure of the cavity is continuously controlled by the pressure regulating unit 3 so that excess liquid and gas are discharged out of the gas hydrate preparation unit 1 through the filtering unit 2 located at the input and output ports 6 of the raw liquid and raw gas in sequence. At this time, what is trapped in the cavity is pure gas hydrate. The pressure regulating unit 3 is used to continue compacting the gas hydrate to exhaust the residual gas and liquid. The physical property parameter detection unit 4 is used to perform in-situ detection of the physical property parameters of the compacted pure gas hydrate sample to obtain the physical property parameters of the pure gas hydrate.

[0055] It can be understood that under the action of the pressure regulating unit 3, gas hydrates are mainly gathered at the bottom of the gas hydrate preparation unit 1. Therefore, in order to facilitate the efficient and accurate detection of gas hydrates by the parameter detection unit 4, the physical property parameter unit 4 can be set on the surrounding wall or bottom wall close to the bottom of the gas hydrate preparation unit 1.

[0056] The existing devices in this field are mainly used to detect the physical parameters of hydrate sediments in small cores. Usually, the length of the core is less than 6 cm, which does not meet the conditions for testing the physical parameters of pure gas hydrates. Hydrate-containing sediments are a mixture of hydrates and sandstones, clays, etc. The measured physical parameters are essentially total physical parameters, which are related to operating conditions such as temperature, pressure, axial stress, and the type of sediment, the shape and distribution of gas hydrates. The obtained results have poor universality and are difficult to be promoted in practical applications.

[0057] The device for preparing gas hydrates and in-situ detection of their physical property parameters of the present invention integrates the preparation of gas hydrates, drainage and exhaust, solid hydrate extrusion molding, and in-situ measurement. It not only realizes the large-scale preparation of pure gas hydrate samples, but also avoids the decomposition and distortion of samples during the transfer process, and finally realizes the determination of important basic physical property parameters of pure gas hydrates, providing important basic data for establishing prediction models such as acoustic wave velocity, heat transfer rate, resistivity, etc. of complex systems.

[0058] In addition, the above-mentioned device can simulate axial stress through the pressure regulating unit, change the pressure acting on the gas hydrate, and simulate the influence of reservoir depth on the physical properties of gas hydrates, which has important reference value for the exploration, development and related application technologies of natural gas hydrates.

[0059] The present invention adopts a multi-segment design for the above-mentioned device, which can not only increase the volume of the gas hydrate preparation unit 1 and increase the gas hydrate preparation amount, but also facilitate the replacement of the physical property parameter detection unit. In-situ detection of multiple physical property parameters can be completed without replacing the reaction device, which greatly simplifies the operation and reduces the manufacturing cost of the device.

[0060] The present invention does not limit the specific form of the gas hydrate preparation unit 1, and it may be, for example, a kettle reactor, a tower reactor, or the like.

[0061] The gas hydrate preparation unit 1 of the present invention is preferably a cylindrical autoclave. To achieve good preparation and separation effects, the height-to-diameter ratio of the autoclave is greater than 10: 1. At the same time, a large height-to-diameter ratio is also conducive to the preparation of large solid pure gas hydrate samples, which is conducive to the detection of physical property parameters.

[0062] In an optional embodiment, the gas hydrate preparation unit 1 of the present invention includes a first pipe segment 7 and a second pipe segment 8 in sequence from top to bottom in the height direction; wherein the first pipe segment 7 is made of metal material, and the second pipe segment 8 is made of metal or visual material.

[0063] Specifically, the visualization material can be selected from a transparent material resistant to high pressure, with a pressure resistance of more than 12 MPa, such as organic polyetheretherketone (PEEK) or fully transparent sapphire, and the metal material can be stainless steel or titanium alloy; preferably, the acoustic wave transducer is made of titanium alloy.

[0064] The first pipe section 7 is made of metal material, which can withstand pressures above 20 MPa and is safe and low-cost. The second pipe section 8 is made of metal or visual material. The visual material is convenient for observing the amount of gas hydrates finally prepared in the cavity to determine whether effective physical property parameter testing is carried out. The metal material is conducive to the installation and replacement of the physical property parameter detection unit 4.

[0065] In a specific embodiment, the physical parameter detection unit 4 includes at least one of a thermal conductivity unit, an acoustic wave velocity detection unit, and a resistivity detection unit. The intrinsic thermal conductivity of pure gas hydrate can be tested by the thermal conductivity unit, the acoustic wave velocity of pure gas hydrate can be tested by the acoustic wave velocity detection unit, and the resistivity of pure gas hydrate can be detected by the resistivity detection unit. The above parameters are all basic physical parameters of pure gas hydrate, which can be accurately measured by the above parameter detection units, and are of great value to the exploration, development, pipeline transportation and other fields of natural gas hydrate.

[0066] Furthermore, the pressure regulating unit 3 of the present invention includes a movable piston, which is placed in the cavity of the gas hydrate preparation unit 1, and the movable piston divides the cavity into a reaction chamber 9 and a pressure regulating chamber 10, and the pressure regulating chamber 10 is located at the upper part of the reaction chamber 9.

[0067] It is understandable that the spatial areas of the reaction chamber 9 and the pressure regulating chamber 10 are not fixed, and the spatial sizes of the reaction chamber 9 and the pressure regulating chamber 10 will change accordingly as the piston moves up and down. As the movable piston moves up and down, the pressure in the reaction chamber 9 will change accordingly, thereby realizing the pressure regulating unit 3 to adjust the internal pressure of the gas hydrate preparation unit 1.

[0068] The present invention does not specifically limit the driving source for driving the movable piston to move. For example, liquid can be used for driving, and the liquid can be a raw material liquid.

[0069] When the driving source is the raw material liquid, the raw material liquid can enter the gas hydrate preparation unit 1 in two ways. One way enters the pressure regulating chamber 10 through the pressurized liquid input port 5 to provide a driving force for the movement of the movable piston, and the other way can directly enter the reaction chamber 9 from the raw material liquid and raw material gas input and output ports 6.

[0070] The axial stress acting on the gas hydrate can also be adjusted by moving the piston, simulating different seawater depths, and obtaining the quantitative relationship between the physical properties of the gas hydrate and the temperature, seawater depth, etc.

[0071] When the pressure regulating unit 3 of the present invention includes a movable piston, the raw material liquid and raw material gas input and output ports 6 of the gas hydrate preparation unit 1 are connected to the reaction chamber 9, so that the raw materials for preparing gas hydrates can enter the reaction chamber 9 from the raw material liquid and raw material gas input and output ports 6 for reaction, and the gas phase and liquid phase compounds to be separated after the reaction can also be discharged from the raw material liquid and raw material gas input and output ports 6 of the gas hydrate preparation unit 1, and the pure gas hydrate is retained as a solid in the reaction chamber 9. Similarly, the physical property parameter detection unit 4 is located on the peripheral wall or bottom wall near the bottom of the reaction chamber 9, so that it can fit closely with the pure gas hydrate and accurately measure its physical property parameters.

[0072] In one embodiment, the filter unit 2 is arranged on the inner wall of the output port, and the filter unit 2 is selected from a filter mesh or a metal filter sintered plate. When the filter unit 2 is arranged on the inner wall of the output port, it is not only beneficial for processing, but also beneficial for retaining all gas hydrates in the reaction chamber.

[0073] Furthermore, the pore diameter of the filter unit 2 is less than 10 μm, which can ensure that when the gas, liquid and solid phases are separated, the gas and liquid can be discharged from the pores, and the gas hydrate is retained in the bottom of the reaction chamber 9 in a solid form.

[0074] In the specific operation process, a temperature control unit can be set in the reaction detection device according to different reaction requirements. The temperature control unit is used to control the temperature of the reaction chamber, so that the preparation of gas hydrate can be carried out at a preset temperature. Specifically, the temperature control unit can be a water bath jacket, a constant temperature chamber, a constant temperature bath, etc.

[0075] The second aspect of the present invention provides a method for preparing gas hydrates and in-situ detection of their physical property parameters. The method uses the device provided by the first aspect of the present invention to prepare gas hydrates and in-situ detection of their physical property parameters. The method comprises the following steps:

[0076] 1) The raw materials enter the cavity of the gas hydrate preparation unit through the input port;

[0077] 2) adjusting the pressure in the cavity by controlling the pressure regulating unit to prepare gas hydrates;

[0078] 3) controlling the pressure regulating unit to filter the reaction system in the cavity through the filtering unit to filter the gas hydrate and the gas-liquid phase, and allowing the filtered gas-liquid phase to be discharged from the gas hydrate preparation unit through the output port;

[0079] 4) Detect the parameters of gas hydrates through the physical property parameter detection unit.

[0080] The raw materials in step 1) refer to raw materials for preparing gas hydrates, including gas and liquid, wherein the gas is methane gas and the liquid is water. The methane gas and water are introduced into the cavity of the gas hydrate preparation unit through the input port.

[0081] In step 2), the pressure in the cavity can be controlled by the pressure regulating unit so that the cavity pressure reaches the experimental preset pressure. Furthermore, when the gas hydrate preparation unit is also connected to a temperature control unit, the temperature in the cavity can be adjusted by the temperature control unit to reach the experimental preset temperature. When the experimental preset pressure and preset temperature reach the gas hydrate formation conditions, gas hydrates can be quickly formed in the reaction chamber. The amount of gas hydrate generated is determined by the distance moved by the pressure regulating unit under constant pressure conditions. The required amount of gas hydrate is determined by the detection requirements and can be adjusted; after the amount of gas hydrate generated is sufficient for detection, the next step can be performed.

[0082] Generally, the preparation of gas hydrates is carried out at 0-15°C and 1.0-15.0 MPa.

[0083] In step 3), the output port of the raw material is adjusted from a closed state to an open state, the pressure in the reaction chamber is maintained constant by controlling the pressure regulating unit, and the reaction system in the reaction chamber is filtered under constant pressure conditions. At this time, the reaction system includes excess water, methane gas and generated gas hydrates. After filtering, the gas hydrates remain in the reaction chamber, and excess water and methane gas are discharged from the gas hydrate preparation unit 1 through the output port of the raw material.

[0084] After the excess water and methane gas are discharged from the gas hydrate preparation unit 1, the physical property parameter detection unit 4 is turned on to detect the physical property parameters of the pure gas hydrate trapped in the reaction chamber.

[0085] Furthermore, after step 3), the method further includes: compressing the gas hydrate by controlling the pressure regulating unit 3 .

[0086] It is understandable that in the process of filtering the gas hydrate and the gas-liquid phase using the filtering unit 2, the gas hydrate has been squeezed to a certain extent and is more compact than the loose and porous original form. In order to make the physical parameter detection unit 4 fit more closely with the gas hydrate, so as to more accurately measure the physical parameters of the gas hydrate, the gas hydrate can be further compressed to compact the gas hydrate.

[0087] Specifically, the compaction standard of gas hydrate is: compressing the gas hydrate until the reading of the physical parameter detection unit 4 is stable and the fluctuation range is within 5%.

[0088] Furthermore, the gas hydrate prepared by the present invention includes pure gas hydrate and sediment containing gas hydrate. The device of the present invention has good applicability to the above two types of gas hydrates.

[0089] In summary, the device and method for preparing gas hydrates and in-situ detection of their physical parameters provided by the present invention integrate the preparation of gas hydrates, drainage and exhaust, solid hydrate extrusion molding, and in-situ measurement. It can not only provide important basic physical parameters of pure gas hydrates, but also provide a basis for establishing prediction models such as acoustic wave velocity, heat transfer rate, and resistivity of complex systems. In addition, the multi-segment design of the above-mentioned device can not only increase the volume of the gas hydrate preparation unit as needed to ensure the preparation of sufficient gas hydrates, but also flexibly and conveniently replace various types of physical property detection means without replacing the reaction device, which not only ensures the effectiveness and accuracy of the test means, but also greatly simplifies the operation and reduces the manufacturing cost. In addition, the above-mentioned device can also simulate the pressure acting on the gas hydrate due to the change of axial stress, and simulate the influence of reservoir depth on the physical parameters of gas hydrates, which has important reference value for the exploration, development and technical utilization of natural gas hydrates.

[0090] 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for preparing gas hydrates and in-situ detection of their physical parameters, characterized in that: It comprises a gas hydrate preparation unit, a pressure regulating unit, a filtering unit, and a physical parameter detection unit; the gas hydrate preparation unit has N interconnected pipe sections in the height direction, N ≥ 2; the gas hydrate preparation unit is provided with an input port and an output port for materials, and the input port and the output port are connected to the cavity of the gas hydrate preparation unit; The pressure regulating unit is connected to the gas hydrate preparation unit, the physical property parameter detection unit is arranged on the peripheral wall or the bottom wall of the gas hydrate preparation unit, and the filtering unit is at least partially located at the output port; In the height direction, the gas hydrate preparation unit comprises a first pipe section and a second pipe section in order from top to bottom; The first pipe section is made of metal material; The material of the second pipe section is a visual material; The input port and the output port are integrated into one port, so that the input and output of raw materials can be completed at different times through the same opening; The filter unit is arranged on the inner wall of the output port, and the filter unit is a metal filter sintered plate; The filter pore diameter of the filter unit is less than 10 μm.

2. The device according to claim 1, characterized in that The gas hydrate preparation unit is a cylindrical autoclave, and the height-to-diameter ratio of the autoclave is greater than 10:

1.

3. The device according to claim 1 or 2, characterized in that: The physical property parameter detection unit includes at least one of a thermal conductivity detection unit, a sound wave velocity detection unit, and a resistivity detection unit.

4. The device according to any one of claims 1 to 3, characterized in that: The pressure regulating unit comprises a movable piston, which is placed in the cavity of the gas hydrate preparation unit and divides the cavity into a reaction chamber and a pressure regulating chamber, and the pressure regulating chamber is located at the upper part of the reaction chamber.

5. A method for preparing gas hydrates and in-situ detection of their physical parameters, characterized in that: The method adopts the device according to any one of claims 1 to 4 to prepare gas hydrates and in-situ detect their physical property parameters, comprising the following steps: 1) The raw materials enter the cavity of the gas hydrate preparation unit through the input port; 2) adjusting the pressure in the cavity by controlling a pressure regulating unit to prepare gas hydrates; 3) controlling the pressure regulating unit to filter the reaction system in the cavity through the filtering unit to filter the gas hydrate and the gas-liquid phase, so that the filtered gas-liquid phase is discharged from the gas hydrate preparation unit through the output port; 4) Detecting the physical property parameters of the gas hydrate by a physical property parameter detection unit.

6. The method according to claim 5, characterized in that After step 3), the method further includes: compressing the gas hydrate by controlling a pressure regulating unit.

7. The method according to claim 5 or 6, characterized in that: The gas hydrates include pure gas hydrates and sediments containing gas hydrates.

Images