Device and method for measuring the wettability of a hydrate surface

Abstract

This invention discloses a device and method for measuring the surface wettability of hydrates. The testing device includes: a hydrate generation mechanism; a visual cavity pressure control mechanism; a droplet mechanism; an image acquisition mechanism; and an analysis and processing mechanism. The measuring device further includes a surrounding liquid phase balancing mechanism, which comprises a stirring vessel, a pressure control structure, and a second temperature control structure. The pressure control structure injects hydrate-generating gas into the stirring chamber to control the pressure of the stirring chamber, and the second temperature control structure controls the temperature of the stirring chamber. The stirring chamber saturates the surrounding liquid phase with hydrate-generating gas through stirring and injects the saturated surrounding liquid phase into the visual cavity. This invention first saturates the surrounding liquid phase with hydrate-generating gas with high efficiency, allowing the surface of water droplets to combine with the hydrate-generating gas in the saturated surrounding liquid phase to form a stable hydrate film, thereby achieving the measurement of the surface wettability of hydrates in a liquid-liquid-solid system.

Description

Technical Field

[0001] This invention relates to the field of hydrate surface wettability research technology, and in particular, to a measuring device and method for measuring hydrate surface wettability. Background Technology

[0002] Hydrates, also known as natural gas hydrates, are non-stoichiometric solid crystals formed by water molecules linked by hydrogen bonds, encasing small gas or liquid molecules (such as methane, carbon dioxide, and cyclopentane). Hydrates require specific low-temperature and high-pressure conditions to remain stable. Natural gas hydrates are widely found in deep-sea sediments and polar permafrost, representing a potential future energy resource. Current research focuses on the exploration and exploitation of natural gas hydrates, aiming to utilize the abundant methane resources stored within them. Furthermore, due to their high energy density, hydrates are also used for natural gas transportation and storage, allowing for the storage of large quantities of natural gas in relatively small spaces, thus reducing transportation and storage costs.

[0003] In recent years, carbon dioxide capture and storage (CCDS) using hydrate technology has become a promising emission reduction method. This process effectively stores the greenhouse gas carbon dioxide by injecting it into the seabed to form hydrates, thus mitigating global warming. However, hydrate formation is a common and challenging problem during oil and gas extraction, transportation, and storage. When water in an oil-gas mixture comes into contact with natural gas under low-temperature and high-pressure conditions, solid hydrates readily form. These hydrates can deposit in pipelines and equipment, obstructing flow and potentially causing blockages and equipment damage. Furthermore, hydrate formation in pipelines is not limited to natural gas pipelines; it can also occur in pipelines transporting mixed oil and gas such as crude oil and condensate containing natural gas. This phenomenon is frequently observed in oil and gas gathering and transportation in cold regions, but it is particularly pronounced in deep-sea oil and gas extraction and transportation because the deep-sea environment provides the low-temperature and high-pressure conditions required for hydrate formation.

[0004] Therefore, hydrate research, as a novel field, has attracted significant attention in areas such as natural gas hydrate extraction, oil and gas fluid storage and transportation blockage prevention, and mixed gas separation. Among these, measuring the contact angle of hydrate surfaces directly characterizes the wettability of the hydrate surface. This not only allows for the prediction of fluid spreading and migration behavior within hydrate-containing interfacial systems during natural gas hydrate extraction but also helps predict interfacial interactions between hydrate solids and other interfaces (such as gas, oil, free water, rock, sediment, and pipeline surfaces) during formation and decomposition in environments like the ocean or oil and gas pipelines. This is of great significance for hydrate extraction and flow assurance. Simultaneously, contact angle measurements can also provide microstructural information such as hydrate surface energy and molecular arrangement, which is crucial for understanding hydrate formation mechanisms and nucleation kinetics. Therefore, measuring the contact angle of hydrate surfaces helps in designing more efficient extraction and transportation methods, significantly reducing technical difficulties and economic costs during extraction, and mitigating the production safety risks associated with hydrate blockage during oil and gas transportation.

[0005] However, existing measuring devices are only suitable for measuring the formation of hydrates and the contact angle in gas-liquid-solid systems under high pressure and low temperature conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a measuring device and method for measuring the surface wettability of hydrates, so as to solve the technical problem that existing measuring devices and methods are not applicable to the formation of hydrates and the measurement of surface wettability of hydrates in liquid-liquid-solid systems.

[0007] The above-mentioned objectives of the present invention can be achieved by the following technical solutions:

[0008] This invention provides a device for measuring the surface wettability of hydrates, comprising: a hydrate generation mechanism including a visible vessel and a first temperature control structure, wherein the visible vessel has a visible cavity inside, and a sample stage is installed inside the visible cavity; the first temperature control structure is used to control the temperature of the visible cavity; a visible cavity pressure control mechanism connected to the visible cavity, which can inject hydrate generation gas into the visible cavity to control the pressure of the visible cavity; a dripping mechanism connected to the visible cavity, wherein the output end of the dripping mechanism can generate droplets, and the output end of the dripping mechanism is located above the sample stage; an image acquisition mechanism installed around the visible vessel, which is used to acquire image data inside the visible cavity; and an analysis and processing mechanism electrically connected to the image acquisition mechanism. The analysis and processing mechanism is used to analyze and process the image data to obtain measurement data on the surface wettability of the hydrate. The measuring device further includes a surrounding liquid phase balancing mechanism, which includes a stirring vessel, a pressure control structure, and a second temperature control structure. The stirring vessel has a stirring chamber inside. The pressure control structure is connected to the stirring chamber and can inject the hydrate-generating gas into the stirring chamber to control the pressure of the stirring chamber. The second temperature control structure is used to control the temperature of the stirring chamber. The stirring chamber is connected to the viewing cavity and is used to contain the surrounding liquid phase and the hydrate-generating gas. By stirring, the surrounding liquid phase is saturated with the hydrate-generating gas, and the saturated surrounding liquid phase can be injected into the viewing cavity.

[0009] In an embodiment of the present invention, the pressure control structure includes a piston container and a first pumping structure. The inner cavity of the piston container is divided into an upper cavity and a lower cavity by a piston. The upper cavity is used to contain the gas generated by the hydrate and is connected to the stirring chamber. The lower cavity is connected to the first pumping structure.

[0010] In an embodiment of the present invention, the stirring chamber is connected to the visual cavity through a first liquid phase injection pipeline, and a liquid phase injection control valve is installed on the first liquid phase injection pipeline.

[0011] In an embodiment of the present invention, the second temperature control structure includes a water bath jacket and a first high-low temperature water bath. The first high-low temperature water bath is used to contain a first heat exchange medium and control the temperature of the first heat exchange medium. The water bath jacket is sleeved outside the stirred tank and connected to the first high-low temperature water bath to form a circulation loop for the first heat exchange medium.

[0012] In an embodiment of the present invention, the image acquisition mechanism includes a light source, a microscope, and a camera. The camera is mounted on the eyepiece end of the microscope and electrically connected to the analysis and processing mechanism. The side wall of the visual vessel has a first viewing window opposite to the light source, a second viewing window opposite to the objective lens end of the microscope, and a third viewing window for observing the test conditions inside the visual cavity. The sample stage is mounted on the bottom wall of the visual vessel via a lifting structure. The top wall of the visual vessel is provided with a first injection connector, a second injection connector, and a third injection connector. The visual cavity pressure control mechanism is connected to the visual cavity through the first injection connector. The dripping mechanism is connected to the visual cavity through the second injection connector. The surrounding liquid phase balance mechanism is connected to the visual cavity through the third injection connector.

[0013] In an embodiment of the present invention, the first temperature control structure includes a visible water bath, a heat exchange coil, a second high-low temperature water bath, and a temperature sensor. The second high-low temperature water bath is used to contain a second heat exchange medium and control the temperature of the second heat exchange medium. The heat exchange coil is installed in the visible water bath and connected to the second high-low temperature water bath to form a circulation loop for the second heat exchange medium. The visible water bath contains a third heat exchange medium. The visible vessel is immersed in the third heat exchange medium. The temperature sensor extends into the visible cavity. The lifting structure includes a lifting screw. The upper end of the lifting screw is installed on the bottom wall of the visible vessel and connected to the sample stage. The lower end of the lifting screw extends out of the visible water bath.

[0014] In an embodiment of the present invention, the dripping mechanism includes a third pumping structure and a dripping needle. The dripping needle is installed in the visual cavity and located above the sample stage. The third pumping structure is connected to the dripping needle through a liquid injection pipeline, and a dripping control valve is installed on the liquid injection pipeline.

[0015] In an embodiment of the present invention, the liquid injection pipeline is further connected to a discharge pipeline, and the discharge pipeline is connected between the drip control valve and the drip needle, and a discharge control valve is installed on the discharge pipeline.

[0016] In an embodiment of the present invention, the visual cavity pressure control mechanism includes a gas cylinder and a second pumping structure. The gas cylinder contains hydrate generation gas. The input end of the second pumping structure is connected to the gas cylinder. The output end of the second pumping structure is connected to the visual cavity through a gas phase injection pipeline. A gas injection control valve and a pressure sensor are installed on the gas injection pipeline along its delivery direction.

[0017] This invention also provides a method for measuring the surface wettability of hydrates, using the aforementioned measuring device. The method includes the following steps: Circulating liquid phase saturation: A preset amount of circulating liquid phase is injected into a stirring chamber, and hydrate-generating gas is injected into the stirring chamber through a pressure control structure. The circulating liquid phase and the hydrate-generating gas are stirred, while the pressure control structure and a second temperature control structure control the stirring chamber to maintain a preset temperature and preset pressure for a preset time, so that the circulating liquid phase is saturated by the hydrate-generating gas; Hydrate generation: Water droplets are dropped onto the sample stage from the output end of the dripping mechanism to form water droplets, and then the visible cavity pressure control mechanism injects hydrate-generating gas into the visible cavity until the visible cavity reaches the preset pressure, at which point the injection of hydrate-generating gas stops; The saturated circulating liquid phase in the stirring chamber is injected into the visible cavity at a preset speed, while the visible cavity pressure control mechanism controls the visible cavity to maintain the preset pressure until the circulating liquid phase in the visible cavity reaches a preset liquid level; The first temperature control structure controls the visible cavity to lower to a preset level. A second preset temperature is set to freeze the water droplet; the first temperature control structure controls the visible cavity to rise to a third preset temperature, causing the surface of the water droplet to melt and combine with the hydrate-generated gas to form a first hydrate film; the first temperature control structure controls the visible cavity to continue rising to a fourth preset temperature, causing the first hydrate film to melt; the first temperature control structure controls the visible cavity to drop to a fifth preset temperature, causing a second hydrate film to form on the surface of the water droplet; droplet testing: the output end of the droplet mechanism forms a test droplet above the sample stage in the visible cavity, causing the test droplet to gradually approach the second hydrate film until the test droplet contacts the second hydrate film, and then immediately separates the test droplet from the output end of the droplet mechanism; wherein, the measurement method further includes image acquisition and analysis during the droplet testing process: the image acquisition mechanism acquires image data in the visible cavity and transmits the image data to the analysis and processing mechanism, and the analysis and processing mechanism analyzes and processes the image data to obtain measurement data of the wettability of the hydrate surface.

[0018] In an embodiment of the present invention, the preset pressure remains constant during the measurement process and is determined based on the hydrate-generating gas used in the experiment, so that the phase equilibrium temperature of the hydrate under the preset pressure is greater than 0°C.

[0019] In an embodiment of the present invention, during the formation of the hydrate, the first preset temperature is higher than 0°C and lower than the phase equilibrium temperature of the hydrate under the preset pressure; the second preset temperature is lower than 0°C; the third preset temperature is higher than 0°C and lower than 2°C; the fourth preset temperature is higher than the phase equilibrium temperature of the hydrate under the preset pressure but does not exceed the phase equilibrium temperature by more than 5°C; the fifth preset temperature is equal to the first preset temperature; wherein, the first temperature control structure controls the visible cavity to cool from the fourth preset temperature to the fifth preset temperature at a cooling rate of 1°C / 5min or by a gradient cooling method, so that a second hydrate film is formed on the surface of the water droplet.

[0020] The features and advantages of this invention are:

[0021] The device and method for measuring the surface wettability of hydrates of the present invention, by adding a surrounding liquid phase balancing mechanism, stirs the surrounding liquid phase and the hydrate generating gas at a preset temperature and preset pressure to saturate the surrounding liquid phase with the hydrate generating gas, and the efficiency is high. Then, the pressure of the visible cavity is controlled by injecting the hydrate generating gas into the visible cavity using a visible cavity pressure control mechanism. Then, the saturated surrounding liquid phase is injected into the visible cavity, so that the surface of the water droplet on the sample stage can combine with the hydrate generating gas in the saturated surrounding liquid phase to form a stable hydrate film, thereby realizing the measurement of the surface wettability of hydrates in the liquid-liquid-solid system.

[0022] The measuring device and method for measuring the surface wettability of hydrates of the present invention first controls the temperature of the visible cavity to form a first hydrate film on the surface of a water droplet, then controls the temperature of the visible cavity to melt the first hydrate film, and then controls the temperature of the visible cavity to form a second hydrate film on the surface of the water droplet. This ensures that the second hydrate film is smooth and flat, thereby improving the accuracy of the measurement results. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the measuring device in this invention;

[0025] Figure 2 This is an exploded view of the visual reactor in this invention;

[0026] Figure 3 This refers to image data acquired during the formation of test droplets in this invention;

[0027] Figure 4 This is image data collected during the formation of a second hydrate film on the surface of a water droplet when the test droplet comes into contact with it, as described in this invention.

[0028] Figure 5 This is image data acquired after the test droplet separates from the droplet-dropping mechanism in this invention.

[0029] In the picture:

[0030] 1. Hydrate generation mechanism; 11. Visual vessel; 111. Vessel body; 112. Base; 113. Top cover; 114. First injection connector; 115. Second injection connector; 116. Third injection connector; 117. First viewing window; 118. Second viewing window; 119. Third viewing window; 12. First temperature control structure; 121. Visual water bath; 122. Heat exchange coil; 123. Second high and low temperature water bath; 124. Temperature sensor; 125. Stirring structure; 13. Sample stage; 14. Lifting structure; 141. Lifting screw;

[0031] 2. Visual cavity pressure control mechanism; 21. Gas cylinder; 22. Second pumping structure; 23. Pressure sensor; 24. Gas phase injection control valve; 25. Output control valve; 26. Input control valve;

[0032] 3. Drip mechanism; 31. Third pumping structure; 32. Second liquid phase injection pipeline; 321. Drip control valve; 33. Drip needle; 34. Discharge control valve;

[0033] 4. Image acquisition mechanism; 41. Light source; 42. Microscope; 43. Camera;

[0034] 5. Analysis and processing unit;

[0035] 6. Surrounding liquid phase balance mechanism; 61. Stirred vessel; 62. Pressure control structure; 621. Piston container; 622. First pumping structure; 623. Pressure control valve; 63. Second temperature control structure; 631. Water bath jacket; 632. First high and low temperature water bath; 64. Liquid phase injection control valve; 65. First liquid phase injection pipeline;

[0036] 7. Test droplets;

[0037] 8. Water droplets;

[0038] 9. Second hydrate membrane;

[0039] 10. The surrounding liquid phase after saturation. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Implementation Method 1

[0042] like Figures 1 to 3 As shown, the present invention provides a device for measuring the surface wettability of hydrates, comprising: a hydrate generation mechanism 1, including a visible vessel 11 and a first temperature control structure 12, wherein the visible vessel 11 has a visible cavity, and a sample stage 13 is installed inside the visible cavity; the first temperature control structure 12 is used to control the temperature of the visible cavity; a visible cavity pressure control mechanism 2, connected to the visible cavity, which can inject hydrate generation gas into the visible cavity and control the pressure of the visible cavity; a dripping mechanism 3, connected to the visible cavity, wherein the output end of the dripping mechanism 3 can generate droplets, and the output end of the dripping mechanism 3 is located above the sample stage 13; an image acquisition mechanism 4, installed around the visible vessel 11, which is used to acquire image data inside the visible cavity; and an analysis and processing mechanism 5, which is connected to the visible cavity. The image acquisition mechanism 4 is electrically connected, and the analysis and processing mechanism 5 is used to analyze and process the image data to obtain measurement data on the wettability of the hydrate surface. The measuring device also includes a surrounding liquid phase balancing mechanism 6, which includes a stirring vessel 61, a pressure control structure 62, and a second temperature control structure 63. The stirring vessel 61 has a stirring chamber inside, and the pressure control structure 62 is connected to the stirring chamber. The pressure control structure 62 can inject the hydrate-generating gas into the stirring chamber and control the pressure of the stirring chamber. The second temperature control structure 63 is used to control the temperature of the stirring chamber. The stirring chamber is connected to the viewing chamber. The stirring chamber is used to contain the surrounding liquid phase and the hydrate-generating gas, and through stirring, the surrounding liquid phase is saturated with the hydrate-generating gas and can be injected into the viewing chamber after saturation.

[0043] The process of measuring the surface wettability of hydrates using the measuring device of the present invention is as follows:

[0044] like Figure 1As shown, saturation of the surrounding liquid phase: A preset amount of surrounding liquid phase is injected into the stirring chamber, and hydrate-generating gas is injected into the stirring chamber through the pressure control structure 62. The surrounding liquid phase and hydrate-generating gas are stirred, and the stirring chamber is maintained at a first preset temperature and preset pressure for a preset time through the pressure control structure 62 and the second temperature control structure 63, so that the surrounding liquid phase is saturated with hydrate-generating gas. The surrounding liquid phase is a liquid hydrocarbon, and the hydrate-generating gas can be methane. In a specific embodiment of the present invention, the preset amount of surrounding liquid phase is 300 ml. When the stirring chamber is maintained at the first preset temperature and preset pressure for 2 hours, it is determined that the surrounding liquid phase is saturated with hydrate-generating gas.

[0045] like Figure 2 As shown, hydrate formation occurs as follows: the output end of the dripping mechanism 3 drops water droplets 8 onto the sample stage 13 to form water droplets 8. Then, the visible cavity pressure control mechanism 2 injects hydrate-generating gas into the visible cavity until the visible cavity reaches a preset pressure, at which point the injection of hydrate-generating gas stops. The saturated surrounding liquid phase 10 in the stirring chamber is injected into the visible cavity at a preset speed, while the visible cavity pressure control mechanism 2 controls the visible cavity to maintain a preset pressure until the surrounding liquid phase in the visible cavity reaches a preset liquid level. The first temperature control structure 12 controls the visible cavity to decrease to a second preset temperature, causing the water droplets 8 to freeze. The first temperature control structure 12 controls the visible cavity to increase to a third preset temperature, causing the surface of the water droplets 8 to melt and combine with the hydrate-generating gas to form a first hydrate film. The first temperature control structure 12 controls the visible cavity to continue increasing until the first hydrate film melts. The first temperature control structure 12 controls the visible cavity to decrease to a fifth preset temperature, causing a second hydrate film 9 to form on the surface of the water droplets 8. The first preset temperature is higher than 0℃ and lower than the phase equilibrium temperature of the hydrate under the preset pressure; the second preset temperature is lower than 0℃, and preferably -10℃ to allow the water droplet to freeze quickly; the third preset temperature is higher than 0℃ and lower than 2℃, preferably 1℃; the fourth preset temperature is higher than the phase equilibrium temperature of the hydrate under the preset pressure but not exceeding 5℃ above the phase equilibrium temperature, preferably 2℃ higher than the phase equilibrium temperature; the fifth preset temperature is equal to the first preset temperature; wherein, the first temperature control structure controls the visible cavity to cool from the fourth preset temperature to the fifth preset temperature at a cooling rate of 1℃ / 5min or by a gradient cooling method, so that a second hydrate film is formed on the surface of the water droplet. By first controlling the temperature of the visible cavity to form a first hydrate film on the surface of the water droplet 8, then controlling the temperature of the visible cavity to melt the first hydrate film, and then controlling the cooling rate of the visible cavity to form a second hydrate film 9 on the surface of the water droplet 8, the second hydrate film 9 can be ensured to be smooth and flat, thereby improving the accuracy of the measurement results;

[0046] The preset pressure remains constant during the measurement process and is determined based on the hydrate generation gas used in the experiment, so that the phase equilibrium temperature of the bound hydrate under the preset pressure is greater than 0℃, thereby ensuring that the generated first and second hydrate films are ice-free hydrate solids.

[0047] like Figures 3 to 5 As shown, the droplet test: The output end of the droplet mechanism 3 forms a test droplet 7 above the sample stage 13 in the visible cavity, so that the test droplet 7 gradually approaches the second hydrate membrane 9, until the test droplet 7 contacts the second hydrate membrane 9 and then immediately separates the test droplet 7 from the output end of the droplet mechanism 3.

[0048] The measurement method also includes image acquisition and analysis during the droplet test: the image acquisition mechanism 4 acquires image data in the visible cavity and transmits the image data to the analysis and processing mechanism 5, which analyzes and processes the image data to obtain measurement data on the wettability of the hydrate surface.

[0049] Specifically, during the droplet test, the image acquisition mechanism 4 acquires image data within the viewing cavity in real time at a preset acquisition frequency. This includes image data acquired during the formation of the test droplet 7, image data acquired as the test droplet 7 and water droplet 8 approach each other until they come into contact with the second hydrate film 9 on their surfaces, and image data acquired after the test droplet 7 separates from the droplet mechanism 3. The measurement data of the hydrate surface wettability includes the contact angle between the test droplet 7 and the second hydrate film 9 after separation from the output end of the droplet mechanism 3. The analysis and processing unit 5 analyzes and processes the image of the test droplet 7 after separation from the droplet mechanism 3 and contact with the second hydrate membrane 9 to obtain the contact angle between the test droplet 7 and the second hydrate membrane 9. The output end of the dripping mechanism 3 forms a test droplet 7 by injecting test liquid (including but not limited to water) into the visual cavity. During the formation of the test droplet 7, the analysis and processing mechanism 5 analyzes and processes the image data acquired by the image acquisition mechanism 4 to determine the size of the test droplet 7. This allows for control of the droplet size to meet requirements and timely cessation of test liquid injection, preventing the droplet 7 from becoming too large and directly contacting the second hydrate membrane 9. In a specific embodiment of the present invention, the volume of the test droplet 7 is no greater than 5 μL. Furthermore, before testing, the visual vessel 11 and its internal sample stage 13 must be thoroughly cleaned and dried to ensure that there are no residual water droplets 8 in the visual cavity or on the sample stage 13.

[0050] The inventors of this invention discovered that, in order to measure the surface wettability of hydrates in a liquid-liquid-solid system, the surrounding liquid phase must first be saturated with hydrate-generating gas at a preset temperature and pressure to allow the surface of water droplet 8 to combine with the hydrate-generating gas to form a stable hydrate film. If the surrounding liquid phase and gas phase (i.e., hydrate-generating gas) are directly introduced into the visible reactor 11, the hydrate film formed by the combination of water droplet 8 and hydrate-generating gas will be unstable, rigid, or even unable to form a hydrate film, making it difficult to subsequently measure the contact angle between the test droplet 7 and the hydrate film. Furthermore, since the mass transfer resistance of the surrounding liquid phase is much greater than that of the gas phase, and the time required for the surrounding liquid phase to be saturated with the gas phase is longer (generally several to tens of hours or even several days), and the general mixing process cannot guarantee that the concentration of hydrate-generating gas in the surrounding liquid phase remains stable at the preset concentration.

[0051] Therefore, the hydrate surface wettability measuring device of the present invention, by adding a surrounding liquid phase balancing mechanism 6, stirs the surrounding liquid phase and the hydrate generating gas at a preset temperature and preset pressure to saturate the surrounding liquid phase with the hydrate generating gas, and the efficiency is high. Then, the pressure of the visible cavity is controlled by injecting the hydrate generating gas into the visible cavity using the visible cavity pressure control mechanism 2. Then, the saturated surrounding liquid phase 10 is injected into the visible cavity, so that the surface of the water droplet 8 on the sample stage 13 can combine with the hydrate generating gas in the saturated surrounding liquid phase 10 to form a stable hydrate film, thereby realizing the measurement of hydrate surface wettability in the liquid-liquid-solid system.

[0052] like Figure 1 As shown, in an embodiment of the present invention, the pressure control structure 62 includes a piston container 621 and a first pumping structure 622. The inner cavity of the piston container 621 is divided into an upper cavity and a lower cavity by a piston. The upper cavity is used to contain the hydrate generation gas and is connected to the stirring chamber, while the lower cavity is connected to the first pumping structure 622. By pressurizing the lower cavity of the piston container 621 through the first pumping structure 622, the hydrate generation gas in the upper cavity of the piston container 621 is forced into the stirring chamber, thereby controlling the pressure in the stirring chamber. Specifically, the first pumping structure 622 includes, but is not limited to, a hand-cranked pump, and a pressure control valve 623 is provided on the connecting pipeline between the first pumping structure 622 and the piston container 621.

[0053] like Figure 1As shown in the embodiment of the present invention, the second temperature control structure 63 includes a water bath jacket 631 and a first high-low temperature water bath 632. The first high-low temperature water bath 632 is used to contain the first heat exchange medium and control its temperature. The water bath jacket 631 is fitted outside the stirred tank 61 and connected to the first high-low temperature water bath 632 to form a circulation loop for the first heat exchange medium. The first heat exchange medium includes, but is not limited to, water. Furthermore, the water bath jacket 631 is wrapped with an insulation layer to prevent heat exchange between the water bath jacket 631 and the outside environment. Of course, the second temperature control structure 63 can also employ other temperature control methods in the prior art for temperature control.

[0054] like Figure 1 As shown, in an embodiment of the present invention, the stirring chamber is connected to the viewing cavity via a first liquid phase injection pipe 65, and a liquid phase injection control valve 64 is installed on the first liquid phase injection pipe 65. Before the surrounding liquid phase is saturated by the gas generated from the hydrate, the liquid phase injection control valve 64 is in a closed state; when it is necessary to inject the saturated surrounding liquid phase 10 into the viewing cavity, the liquid phase injection control valve 64 is opened. Furthermore, by closing the liquid phase injection control valve 64, the use of the surrounding liquid phase balancing mechanism 6 is stopped, so that the hydrate surface wettability measuring device of the present invention can also be applied to the measurement of hydrate surface wettability in a gas-liquid-solid system. The specific measurement process can be the same as in the prior art, and will not be described in detail here.

[0055] like Figure 1 As shown, in an embodiment of the present invention, the first temperature control structure 12 includes a visible water bath 121, a heat exchange coil 122, a second high-low temperature water bath 123, and a temperature sensor 124. The second high-low temperature water bath 123 is used to contain a second heat exchange medium and control its temperature. The heat exchange coil 122 is installed in the visible water bath 121 and connected to the second high-low temperature water bath 123 to form a circulation loop for the second heat exchange medium. The visible water bath 121 contains a third heat exchange medium, and the visible vessel 11 is immersed in the third heat exchange medium. The temperature sensor 124 extends into the visible cavity. After the temperature of the second heat exchange medium is adjusted by the second high-low temperature water bath 123, it is input into the heat exchange coil 122, so that the second heat exchange medium and the third heat exchange medium exchange heat. The temperature of the visible cavity of the visible vessel 11 is controlled by the third heat exchange medium. The second heat exchange medium includes, but is not limited to, an aqueous solution of ethylene glycol. The first temperature control structure 12 can achieve temperature control of the visible cavity from -30℃ to 100℃. The temperature sensor 124 can be a resistive temperature sensor, such as a PT100 resistive temperature sensor, with an accuracy of ±0.1℃. The visible water bath 121 can be a tank structure made of colorless and transparent plexiglass. Furthermore, the first temperature control structure 12 includes a stirring structure 125 for stirring the third heat exchange medium within the visible water bath 121, thereby making the temperature distribution of the third heat exchange medium more uniform.

[0056] like Figure 1 As shown, in an embodiment of the present invention, the dripping mechanism 3 includes a third pumping structure 31 and a dripping needle 33. The dripping needle 33 is installed in the viewing cavity and located above the sample stage 13. The third pumping structure 31 is connected to the dripping needle 33 through a second liquid phase injection line 32, and a dripping control valve 321 is installed on the second liquid phase injection line 32. In addition, a discharge line is provided on the second liquid phase injection line 32, and the discharge line is connected between the dripping control valve 321 and the dripping needle 33. A discharge control valve 34 is installed on the discharge line. First, open the discharge control valve 34 and close the drip control valve 321. Then, inject the hydrate-generating gas into the visual cavity through the visual cavity pressure control mechanism 2 until all the air in the visual cavity is discharged from the discharge pipe. Then, close the discharge control valve 34 and continue to inject the hydrate-generating gas into the visual cavity until the visual cavity reaches the preset pressure. After the saturated surrounding liquid phase 10 is injected into the visual cavity, open the drip control valve 321 and use the third pumping structure 31 to pump water from the drip needle 33 to form water droplets 8, which then drip onto the sample stage 13. During the drip test, open the drip control valve 321 and use the third pumping structure 31 to pump the test liquid from the drip needle 33 to form test droplets 7, but do not drip or contact the water droplets 8. The third pumping structure 31 can be a hand pump or other liquid pumps of the prior art. The material of the droplet needle 33 can be selected according to the interfacial tension between the test droplet 7 and the surrounding liquid phase, such as a droplet needle 33 made of 316L stainless steel or a droplet needle 33 made of polytetrafluoroethylene, to ensure that the test droplet 7 can be smoothly detached from the droplet needle 33 and transferred to the hydrate membrane.

[0057] like Figure 1 As shown, in this embodiment of the invention, the visual cavity pressure control mechanism 2 includes a gas cylinder 21 and a second pumping structure 22. The gas cylinder 21 contains hydrate-generating gas. The input end of the second pumping structure 22 is connected to the gas cylinder 21, and the output end of the second pumping structure 22 is connected to the visual cavity through a gas phase injection pipeline. A gas phase injection control valve 24 and a pressure sensor 23 are installed on the gas phase injection pipeline along its delivery direction. After the gas phase injection control valve 24 is opened, the second pumping structure 22 pumps the hydrate-generating gas into the visual cavity according to the pressure detection signal of the pressure sensor 23. In addition, an output control valve 25 and an input control valve 26 are provided on the connecting pipeline between the input end of the second pumping structure 22 and the gas cylinder 21. The output control valve 25 is located near the output end of the gas cylinder 21 to control the outflow of hydrate-generating gas from the gas cylinder 21; the input control valve 26 is located near the input end of the second pumping structure 22 to control the inflow of hydrate-generating gas into the second pumping structure 22. The second pumping structure 22 can be a high-precision plunger pump or other air pumps with existing technology.

[0058] like Figure 1 and Figure 2 As shown, in an embodiment of the present invention, the image acquisition mechanism 4 includes a light source 41, a microscope 42, and a camera 43. The camera 43 is mounted on the eyepiece end of the microscope 42 and electrically connected to the analysis and processing mechanism 5. The side wall of the visual vessel 11 has a first viewing window 117 opposite to the light source 41, a second viewing window 118 opposite to the objective lens end of the microscope 42, and a third viewing window 119 for observing the test conditions inside the visual cavity. The sample stage 13 is mounted on the bottom wall of the visual vessel 11 via a lifting structure 14. The top wall of the visual vessel 11 is provided with a first injection connector 114, a second injection connector 115, and a third injection connector 116. The visual cavity pressure control mechanism 2 is connected to the visual cavity via the first injection connector 114. The dripping mechanism 3 is connected to the visual cavity via the second injection connector 115. The surrounding liquid phase balance mechanism 6 is connected to the visual cavity via the third injection connector 116. During the droplet test, the test droplet 7 is initially fixed in place. The lifting structure 14 drives the sample stage 13 to rise, causing the water droplet 8 on the sample stage 13 to gradually approach the test droplet 7. Once the second hydrate film 9 on the surface of the water droplet 8 comes into contact with the test droplet 7, the lifting structure 14 drives the sample stage 13 to fall, causing the test droplet 7 to separate from the output end of the droplet mechanism 3.

[0059] Specifically, the sample stage 13 can be provided with a groove to accommodate water droplets 8. The size of the groove can be set as needed, such as a circular groove with a diameter of 2mm, 4mm, 6mm, 8mm, 10mm, or other sizes. The lifting structure 14 includes a lifting screw 141. The upper end of the lifting screw 141 is installed on the bottom wall of the visual vessel 11 and connected to the sample stage 13. The lower end of the lifting screw 141 extends out of the visual water bath 121. By operating the lower end of the lifting screw 141 to rotate the lifting screw 141, the lifting screw 141 drives the sample stage 13 to move up and down. The first viewing window 117, the second viewing window 118, and the third viewing window 119 can all be sapphire viewing windows. The visual reactor 11 includes a reactor body 111 forming its side walls, a base 112 forming its bottom wall, and a top cover 113 forming its top wall. The base 112 is sealed and installed at the bottom opening of the reactor body 111 by multiple fasteners, and the top cover 113 is sealed and installed at the top opening of the reactor body 111 by multiple fasteners. A drip needle 33 is installed at the lower end of the second injection connector 115, and the upper end of the second injection connector 115 is connected to the second liquid phase injection pipeline 32. The side walls of the visual reactor 11 are generally square-shaped, with the first viewing window 117 and the second viewing window 118 located on two opposite walls. The camera 43 can be an online CCD camera 43. The analysis and processing unit 5 is a computer with corresponding analysis and processing software installed.

[0060] Implementation Method 2

[0061] Combination Figures 1 to 5 As shown, the present invention also provides a method for measuring the wettability of hydrate surfaces, using the measuring device in Embodiment 1. Therefore, the implementation of the measurement method can refer to the implementation of the measuring device in Embodiment 1, and will not be repeated here.

[0062] The measurement method of the present invention includes the following steps: Saturation of the surrounding liquid phase: A preset amount of surrounding liquid phase is injected into the stirring chamber, and hydrate-generating gas is injected into the stirring chamber through the pressure control structure 62. The surrounding liquid phase and hydrate-generating gas are stirred, and the stirring chamber is maintained at a first preset temperature and preset pressure for a preset time through the pressure control structure 62 and the second temperature control structure 63, so that the surrounding liquid phase is saturated by the hydrate-generating gas; Hydrate generation: The output end of the dripping mechanism 3 drops water droplets 8 onto the sample stage 13 to form water droplets 8. Then, the visible cavity pressure control mechanism 2 injects hydrate-generating gas into the visible cavity until the visible cavity reaches a preset pressure, after which the injection of hydrate-generating gas is stopped; The saturated surrounding liquid phase 10 in the stirring chamber is injected into the visible cavity at a preset speed, while the visible cavity pressure control mechanism 2 controls the visible cavity to maintain a preset pressure until the surrounding liquid phase in the visible cavity reaches a preset liquid level; The first temperature control structure 12 controls the visible cavity to decrease to a second preset temperature, so that the water droplets... 8. Freezing; The first temperature control structure 12 controls the visible cavity to rise to the third preset temperature, causing the surface of the water droplet 8 to melt and combine with the gas generated by the hydrate to form a first hydrate film; The first temperature control structure 12 controls the visible cavity to continue to rise to the fourth preset temperature, causing the first hydrate film to melt; The first temperature control structure 12 controls the visible cavity to drop to the fifth preset temperature, causing the surface of the water droplet 8 to form a second hydrate film 9; Droplet test: The output end of the droplet mechanism 3 forms a test droplet 7 above the sample stage 13 in the visible cavity, causing the test droplet 7 to gradually approach the second hydrate film 9, until the test droplet 7 contacts the second hydrate film 9 and immediately separates the test droplet 7 from the output end of the droplet mechanism 3; The measurement method also includes image acquisition and analysis during the droplet test: The image acquisition mechanism 4 acquires image data in the visible cavity and transmits the image data to the analysis and processing mechanism 5, and the analysis and processing mechanism 5 analyzes and processes the image data to obtain the measurement data of the wettability of the hydrate surface.

[0063] The preset pressure remains constant during the measurement process and is determined based on the hydrate generation gas used in the experiment, so that the phase equilibrium temperature of the bound hydrate under the preset pressure is greater than 0℃, thereby ensuring that the generated first and second hydrate films are ice-free hydrate solids.

[0064] In the embodiments of the present invention, during the formation of hydrates, the first preset temperature is higher than 0°C and lower than the phase equilibrium temperature of the hydrate under preset pressure; the second preset temperature is lower than 0°C, and to make the water droplets freeze quickly, the second preset temperature is preferably -10°C; the third preset temperature is higher than 0°C and lower than 2°C, preferably 1°C; the fourth preset temperature is higher than the phase equilibrium temperature of the hydrate under preset pressure but does not exceed the phase equilibrium temperature by more than 5°C, preferably 2°C higher than the phase equilibrium temperature; the fifth preset temperature is equal to the first preset temperature; wherein, the first temperature control structure 12 controls the visible cavity to decrease from the fourth preset temperature to the fifth preset temperature at a cooling rate of 1°C / 5min or by a gradient cooling method, so that a second hydrate film 9 is formed on the surface of the water droplet 8.

[0065] The above descriptions are merely a few embodiments of the present invention. Those skilled in the art can make various modifications or variations to the embodiments of the present invention based on the content disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A device for measuring the surface wettability of hydrates, characterized in that, include: A hydrate generation mechanism includes a visible vessel and a first temperature control structure. The visible vessel has a visible cavity inside, and a sample stage is installed inside the visible cavity. The first temperature control structure is used to control the temperature of the visible cavity. A visible cavity pressure control mechanism is connected to the visible cavity, and the visible cavity pressure control mechanism can inject hydrate-generating gas into the visible cavity to control the pressure of the visible cavity; A droplet-generating mechanism is connected to the visible cavity. The output end of the droplet-generating mechanism can generate droplets, and the output end of the droplet-generating mechanism is located above the sample stage. An image acquisition mechanism is installed around the visible cavity, and the image acquisition mechanism is used to acquire image data within the visible cavity; An analysis and processing mechanism is electrically connected to the image acquisition mechanism. The analysis and processing mechanism is used to analyze and process the image data to obtain measurement data on the surface wettability of the hydrate. The measuring device further includes a surrounding liquid phase balancing mechanism, which includes a stirring vessel, a pressure control structure, and a second temperature control structure. The stirring vessel has a stirring chamber inside. The pressure control structure is connected to the stirring chamber and can inject the hydrate-generating gas into the stirring chamber to control the pressure of the stirring chamber. The second temperature control structure is used to control the temperature of the stirring chamber. The stirring chamber is connected to the viewing cavity. The stirring chamber is used to contain the surrounding liquid phase and the hydrate-generating gas, and through stirring, the surrounding liquid phase is saturated with the hydrate-generating gas, and the saturated surrounding liquid phase can be injected into the viewing cavity.

2. The measuring device as described in claim 1, characterized in that, The pressure control structure includes a piston container and a first pumping structure. The inner cavity of the piston container is divided into an upper cavity and a lower cavity by the piston. The upper cavity is used to contain the gas generated by the hydrate and is connected to the stirring chamber. The lower cavity is connected to the first pumping structure.

3. The measuring device as described in claim 1, characterized in that, The stirring chamber is connected to the visual cavity through a first liquid phase injection pipeline, and a liquid phase injection control valve is installed on the first liquid phase injection pipeline.

4. The measuring device as described in claim 1, characterized in that, The second temperature control structure includes a water bath jacket and a first high-low temperature water bath. The first high-low temperature water bath is used to contain the first heat exchange medium and control the temperature of the first heat exchange medium. The water bath jacket is sleeved outside the stirred tank and connected to the first high-low temperature water bath to form a circulation loop for the first heat exchange medium.

5. The measuring device as described in claim 1, characterized in that, The image acquisition mechanism includes a light source, a microscope, and a camera. The camera is mounted on the eyepiece end of the microscope and is electrically connected to the analysis and processing mechanism. The side wall of the visual vessel has a first viewing window opposite to the light source, a second viewing window opposite to the objective lens end of the microscope, and a third viewing window for observing the test conditions inside the visual cavity. The sample stage is installed on the bottom wall of the visual vessel via a lifting structure. The top wall of the visual vessel is provided with a first injection connector, a second injection connector, and a third injection connector. The visual cavity pressure control mechanism is connected to the visual cavity through the first injection connector. The dripping mechanism is connected to the visual cavity through the second injection connector. The surrounding liquid phase balance mechanism is connected to the visual cavity through the third injection connector.

6. The measuring device as described in claim 5, characterized in that, The first temperature control structure includes a visible water bath, a heat exchange coil, a second high-low temperature water bath, and a temperature sensor. The second high-low temperature water bath is used to contain a second heat exchange medium and control the temperature of the second heat exchange medium. The heat exchange coil is installed in the visible water bath and connected to the second high-low temperature water bath to form a circulation loop for the second heat exchange medium. The visible water bath contains a third heat exchange medium. The visible vessel is immersed in the third heat exchange medium. The temperature sensor extends into the visible cavity. The lifting structure includes a lifting screw. The upper end of the lifting screw is installed on the bottom wall of the visible vessel and connected to the sample stage. The lower end of the lifting screw extends out of the visible water bath.

7. The measuring device as described in claim 1, characterized in that, The dripping mechanism includes a third pumping structure and a dripping needle. The dripping needle is installed in the visual cavity and above the sample stage. The third pumping structure is connected to the dripping needle through a second liquid phase injection line, and a dripping control valve is installed on the second liquid phase injection line.

8. The measuring device as described in claim 7, characterized in that, The second liquid phase injection line is connected to a discharge line, and the discharge line is connected between the drip control valve and the drip needle. The discharge line is equipped with a discharge control valve.

9. The measuring device as claimed in claim 1, characterized in that, The visual cavity pressure control mechanism includes a gas cylinder and a second pumping structure. The gas cylinder contains hydrate generation gas. The input end of the second pumping structure is connected to the gas cylinder, and the output end of the second pumping structure is connected to the visual cavity through a gas phase injection pipeline. A gas phase injection control valve and a pressure sensor are installed on the gas phase injection pipeline along its delivery direction.

10. A method for measuring the surface wettability of hydrates, characterized in that, The measuring method using the measuring apparatus according to any one of claims 1-9 includes the following steps: Surrounding liquid phase saturation: A preset amount of surrounding liquid phase is injected into the stirring chamber and hydrate generating gas is injected into the stirring chamber through a pressure control structure. The surrounding liquid phase and the hydrate generating gas are stirred. At the same time, the stirring chamber is controlled by the pressure control structure and the second temperature control structure to maintain the stirring chamber at a first preset temperature and preset pressure for a preset time, so that the surrounding liquid phase is saturated by the hydrate generating gas. Hydrate formation: The output end of the dripping mechanism drops water onto the sample stage to form a water droplet. Then, the visible cavity pressure control mechanism injects hydrate-generating gas into the visible cavity until the visible cavity reaches the preset pressure, at which point the injection of the hydrate-generating gas stops. The saturated surrounding liquid phase in the stirring chamber is injected into the visible cavity at a preset speed, while the visible cavity pressure control mechanism controls the visible cavity to maintain the preset pressure until the surrounding liquid phase in the visible cavity reaches a preset liquid level. The first temperature control structure controls the visible cavity to decrease to a second preset temperature, causing the water droplet to freeze. The first temperature control structure controls the visible cavity to increase to a third preset temperature, causing the surface of the water droplet to melt and combine with the hydrate-generating gas to form a first hydrate film. The first temperature control structure controls the visible cavity to continue increasing to a fourth preset temperature, causing the first hydrate film to melt. The first temperature control structure controls the visible cavity to decrease to a fifth preset temperature, causing a second hydrate film to form on the surface of the water droplet. Droplet test: The output end of the droplet mechanism forms a test droplet above the sample stage in the visible cavity, so that the test droplet gradually approaches the second hydrate membrane until the test droplet contacts the second hydrate membrane and then immediately separates the test droplet from the output end of the droplet mechanism; The measurement method further includes image acquisition and analysis during the droplet test: the image acquisition mechanism acquires image data within the visible cavity and transmits the image data to the analysis and processing mechanism, which analyzes and processes the image data to obtain measurement data on the wettability of the hydrate surface.

11. The method for measuring the surface wettability of hydrates as described in claim 10, characterized in that, The preset pressure remains constant during the measurement process and is determined based on the gas generated by the hydrate used in the experiment, so that the phase equilibrium temperature of the hydrate under the preset pressure is greater than 0°C.

12. The method for measuring the surface wettability of hydrates as described in claim 10, characterized in that, During the formation of the hydrate, the first preset temperature is higher than 0°C and lower than the phase equilibrium temperature of the hydrate under the preset pressure; the second preset temperature is lower than 0°C; the third preset temperature is higher than 0°C and lower than 2°C; the fourth preset temperature is higher than the phase equilibrium temperature of the hydrate under the preset pressure but does not exceed the phase equilibrium temperature by more than 5°C; and the fifth preset temperature is equal to the first preset temperature. The first temperature control structure controls the visible cavity to cool from the fourth preset temperature to the fifth preset temperature at a cooling rate of 1℃ / 5min or in a gradient cooling manner, so that a second hydrate film is formed on the surface of the water droplet.

Images