An experimental device and method for measuring the phase characteristics of fluids

Abstract

The present invention relates to an experimental device and method for determining the phase state characteristics of fluids, belonging to the technical field of high-pressure fluid phase states and physical property analysis. The experimental device includes the following systems: a fluid phase change system, including a fused silica capillary and a connecting pipeline, for accommodating fluids to carry out phase change reactions; a temperature control system, for controlling the temperature of the fluid phase change system; a fluid injection system, for injecting fluids into the fluid phase change system; a pressure control system, for controlling the pressure of the phase change reaction system; and a data acquisition system, for observing and recording data. The experimental method includes a gas dew point test method, a liquid bubble point test method, a fluid PVT relationship and liquid volume test method. The present invention requires a small sample volume for testing, is easy to mix evenly, has intuitive and visible results, can quickly and accurately determine the phase state characteristics of fluids, is simple to operate, has a fast test speed, has a wide range of applications, and can determine the phase state characteristics of fluids such as ultra-high temperature, ultra-high pressure, and high-acid gas-containing oil and gas.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas engineering, and particularly to an experimental device and method for measuring the phase state characteristics of high-pressure fluids. Background Art

[0002] Taking the measurement of condensate gas phase state characteristics as an example to introduce the application background of the present invention. A condensate gas reservoir is a complex type of oil and gas reservoir between a pure gas reservoir and an oil reservoir, and has high economic value for exploitation. Under formation (high temperature, high pressure) conditions, condensate gas usually exists in a gaseous state. However, due to the change of environmental temperature and pressure during the exploitation process, the condensate gas may condense into condensate oil and natural gas. Therefore, the phase state properties of condensate gas are very complex. To achieve the efficient development of condensate gas reservoirs, it is very important to clarify the phase state characteristics such as the bubble point, dew point, and gas-liquid ratio of condensate oil and gas under different temperature and pressure conditions.

[0003] A PVT analyzer is an essential research equipment for carrying out research on the phase state characteristics of high-pressure condensate gas. The ultra-high temperature, ultra-high pressure conditions and visualization requirements for measuring the phase state characteristics such as the bubble and dew points and gas-liquid ratio of condensate oil and gas pose extremely high requirements for the research and development of PVT analyzers. The French company Sanchez Technologies has developed a PVT analyzer for measuring the phase state characteristics of oil and gas, which can realize the visual experimental measurement of the phase state characteristics of oil and gas under high temperature and high pressure conditions. Among them, the PVT cell can be automatically flipped to promote mass transfer and heat transfer, enabling the oil and gas fluids to be fully mixed. At present, imported PVT analyzers are the main choice for realizing the visual experimental measurement of the phase state characteristics of oil and gas. However, imported PVT analyzers are expensive to purchase and have high testing costs. If the instrument fails, the foreign manufacturer has a long maintenance cycle and high maintenance costs. Therefore, the existing PVT analysis instruments cannot meet the long-term needs of testing the phase state characteristics of ultra-high temperature and ultra-high pressure oil and gas.

[0004] Therefore, in view of the current situation of the difficult visual experimental measurement and high testing cost of the phase state characteristics of ultra-high temperature and ultra-high pressure oil and gas, it is necessary to establish an experimental device and method for measuring the phase state characteristics such as the bubble and dew points and gas-liquid ratio of oil and gas, reduce the cost of measuring the phase state characteristics of high-pressure oil and gas, and meet the needs of long-term stable testing. Summary of the Invention

[0005] Aiming at the current deficiencies, the present invention provides an experimental device and method for measuring the phase state characteristics of fluids. The present invention is realized through the following technical solutions:

[0006] An experimental device for measuring the phase state characteristics of fluids includes a fluid phase change system, a temperature control system, a fluid injection system, a pressure control system, and a data acquisition system.

[0007] The fluid phase change system includes a fused silica capillary, a connecting pipeline, a first three-way valve, and a second three-way valve. The fused silica capillary is used to accommodate the fluid to be tested for phase change reaction. The fused silica capillary is inserted into the interior of the connecting pipeline and sealed with epoxy resin glue. The first three-way valve and the second three-way valve are respectively connected to both ends of the fused silica capillary to control the entry or discharge of the fluid to be tested. Preferably, the inner diameter of the fused silica capillary ranges from 500 nm to 100 μm, and the outer diameter ranges from 100 μm to 3 mm. Preferably, the fluid phase change system is placed vertically.

[0008] The temperature control system is connected to the fluid phase change system to control the temperature of the fluid phase change system. Optionally, the temperature control system includes a high and low temperature console, a groove, a fixing strap, and a temperature control panel. The high and low temperature console is used to circulate the temperature of the fluid to control the temperature of the fused silica capillary submerged therein. The circulating fluid includes heat-conducting oil or refrigerating nitrogen. The groove of the high and low temperature console is used to accommodate the heat-conducting material. The fixing strap is used to fix the fused silica capillary in the groove. The temperature control panel is used to set the temperature of the high and low temperature console, and the temperature control panel is connected to the high and low temperature console through a cable.

[0009] The fluid injection system is connected to the fluid phase change system to inject the fluid to be tested into the fluid phase change system. Optionally, the fluid injection system includes a gas injection unit and an oil / water injection unit. The fluid to be tested includes the gas of the gas injection unit and the oil / water of the oil / water injection unit. The gas injection unit includes a gas cylinder, a pressure reducing valve, a first valve, and an air inlet pipeline. The gas cylinder is the gas source. The pressure reducing valve is used to regulate the inlet air pressure. The gas cylinder and the pressure reducing valve are connected to the first three-way valve of the fluid phase change system through the first valve and the air inlet pipeline. The oil / water injection unit includes an oil / water pump, a second valve, and an oil / water pipeline. The oil / water pump is used to inject oil / water into the fluid phase change system. The oil / water pump is connected to the first three-way valve of the fluid phase change system through the second valve and the oil / water pipeline.

[0010] The pressure control system is connected to the fluid phase change system and is used to control the pressure of the fluid to be measured in the fluid phase change system. Optionally, the pressure control system includes a pressure control pump, a buffer tank, a third valve, a four-way joint, a three-way joint, a drainage unit, and a vacuum unit. The pressure control pump is used to inject a pressure control fluid into the fluid phase change system to control the pressure of the phase change system; the buffer tank is used to buffer the injection of the pressure control fluid; the pressure control pump is connected to the buffer tank through the third valve, the four-way joint, the three-way joint, and a pipeline in sequence; the other two ends of the four-way joint are respectively connected to a first three-way valve and a second three-way valve. Preferably, the pressure control fluid is mercury or indium gallium alloy, and more preferably, the pressure control fluid is indium gallium alloy. The drainage unit is a drainage pipeline and is used to drain the fluid to be measured in the fluid phase change system; the vacuum unit includes a vacuum pump, a fourth valve, and a pipeline and is used to remove the air in the fluid phase change system. The drainage unit and the vacuum unit are connected to the second three-way valve of the fluid phase change system.

[0011] The data acquisition system is used to obtain the phase state of the fluid to be measured in the fluid phase change system. Optionally, the data acquisition system includes a pressure acquisition unit and an image acquisition unit. The pressure acquisition unit includes a pressure sensor, a pipeline, a data acquisition line, and a data recorder. The pressure sensor is used to acquire the pressure data of the experimental device; the data recorder is used to record and store the acquired pressure data; the pressure sensor is connected to the three-way joint of the pressure control system through a pipeline and is connected to a data acquisition instrument through a data acquisition line. The image acquisition unit includes a high-resolution camera, a cable, and a computer. The high-resolution camera is used to photograph the gas-liquid distribution of the fluid to be measured in the fused silica capillary; the computer is connected to the high-resolution camera through a cable and is used to observe and store the image information in real time.

[0012] An experimental method for measuring the phase state characteristics of a fluid includes a gas dew point test method, a liquid bubble point test method, a fluid PVT relationship, and a liquid volume test method.

[0013] The gas dew point test method includes the following steps:

[0014] (A1) Use the vacuum pump to evacuate the experimental device to remove the air in the experimental device. Open the gas cylinder, adjust the pressure reducing valve to the set pressure, and inject gas into the fluid phase change system;

[0015] (A2) Adjust the temperature control panel to raise the temperature of the high and low temperature console to the set value;

[0016] (A3) Use the pressure control pump to inject a pressure control fluid into the fluid phase change system, adjust the first three-way valve and the second three-way valve at the left and right to make the gas located in the groove of the high and low temperature control platform, and increase the pressure in the fluid phase change system to the set value;

[0017] (A4) Use the high-resolution camera to observe and record the fluid in the fused silica capillary. Lower or raise the pressure in the fluid phase change system. When the temperature and pressure at which the liquid phase begins to appear in the fused silica capillary are the dew point conditions;

[0018] (A5) Change the temperature setting value in step (A2), and repeat step (A4) to obtain multiple dew point conditions.

[0019] The liquid bubble point test method includes the following steps:

[0020] (B1) Use the vacuum pump to evacuate the experimental device to remove the air in the experimental device. Subsequently, use an oil / water injection pump to inject a certain volume of oil / water into the fluid phase change system;

[0021] (B2) Use a pressure control pump to inject a pressure control fluid into the fluid phase change system. Adjust the first three-way valves at both left and right and the second three-way valve so that the oil / water is located in the groove of the high and low temperature control platform. Detect the pressure in the device through the pressure acquisition unit, and adjust the temperature and pressure of the fluid phase change system to the set values through the temperature control panel and the pressure control pump;

[0022] (B3) Use the high-resolution camera to observe and record the fluid in the fused silica capillary. Lower or raise the pressure in the fluid phase change system. When the temperature and pressure at which the gas phase begins to appear in the fused silica capillary are the bubble point conditions;

[0023] (B4) Change the temperature setting value in step (B2), and repeat step (B3) to obtain multiple bubble point conditions.

[0024] The fluid PVT relationship and liquid volume test method includes the following steps:

[0025] (C1) Use the vacuum pump to evacuate the experimental device to remove the air in the experimental device. Use an oil / water injection pump to inject a certain volume of oil / water into the fluid phase change system. Subsequently, open the gas cylinder, adjust the pressure reducing valve to the set pressure, and inject gas into the fluid phase change system;

[0026] (C2) Use a pressure control pump to inject a pressure control fluid into the fluid phase change system. Adjust the first three-way valves at both left and right and the second three-way valve so that the oil / water and gas mixture is located in the groove of the high and low temperature control platform. Detect the pressure in the device through the pressure acquisition unit, and adjust the temperature and pressure of the fluid phase change system to the set values through the temperature control panel and the pressure control pump;

[0027] (C3) Use the high-resolution camera to observe and record the fluid in the fused silica capillary, and reduce or increase the pressure in the fluid phase change system. Calculate the oil phase volume according to the distributions of the oil / water phase and gas phase in the fused silica capillary and the gas phase volume to obtain the PVT relationship and gas-liquid ratio of the fluid

[0028] (C4) Change the temperature set value in step (C2), and repeat step (C3) to obtain multiple fluid PVT relationships and liquid volume conditions.

[0029] The beneficial effects of the present invention are as follows:

[0030] (1) The experimental device provided by the present invention requires a small sample volume, is less restricted by mass transfer and heat transfer, the sample is easily mixed evenly, the result is intuitive and visible, and the phase characteristics of the fluid can be measured quickly and accurately.

[0031] (2) The test method provided by the present invention is simple to operate, has a fast test speed, a wide application range, and can measure the phase characteristics of fluids such as ultra-high temperature, ultra-high pressure, and high-acid-gas-containing oil and gas. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the composition of the experimental device for measuring the fluid phase characteristics in the embodiment of the present invention.

[0033] Among them, 1 - fused silica capillary, 2 - connecting pipeline, 3 - sealed with epoxy resin glue, 4 - first three-way valve, 5 - high and low temperature control console, 6 - groove, 7 - fixing strap, 8 - temperature control panel, 9 - cable, 10 - gas cylinder, 11 - pressure reducing valve, 12 - first valve, 13 - gas injection pipeline, 14 - oil / water injection pump, 15 - oil / water injection pipeline, 16 - pressure control pump, 17 - buffer tank, 18 - four-way joint, 19 - three-way joint, 20 - pressure sensor, 21 - data acquisition instrument, 22 - vacuum pump, 23 - evacuation pipeline, 24 - high-resolution camera, 25 - computer. Detailed Embodiments

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the content in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0036] Example 1

[0037] As Figure 1 shown, the present invention provides an experimental device for measuring the phase state characteristics of a fluid, including a fluid phase change system, a temperature control system, a fluid injection system, a pressure control system, and a data acquisition system.

[0038] The fluid phase change system includes a fused silica capillary 1, a connecting pipeline 2, a first three-way valve 4, and a second three-way valve. In Figure 1 it, the fused silica capillary 1 has an inverted "U" shape. The two ends of the fused silica capillary 1 are connected to the connecting pipeline 2 and inserted into the interior of the connecting pipeline 2, and the connection is sealed with epoxy resin glue. Among them, the first end of the fused silica capillary 1 is connected to the first three-way valve 4, and the second end of the fused silica capillary 1 is connected to the second three-way valve. The first three-way valve 4 and the second three-way valve are connected through a four-way joint 18, and the four-way joint 18 is also connected to a pressure control pump 16 through a pipeline.

[0039] Preferably, the inner diameter of the fused silica capillary 1 is 75 μm, the outer diameter is 375 μm, the temperature range is -60°C to 320°C, and the maximum pressure bearing is 138 MPa.

[0040] Preferably, a scale is also provided on the fused silica capillary 1 to facilitate reading the fluid volume in the fused silica capillary 1.

[0041] The temperature control system includes a high and low temperature console 5, a groove 6, a fixing strap 7, and a temperature control panel 8. The temperature control panel 8 is connected to the high and low temperature console 5 through a cable 9. The high and low temperature console 5 contains circulating heat-conducting oil; the groove 6 of the high and low temperature console 5 is filled with heat-conducting silicone, and the fused silica capillary 1 and the connecting pipeline 2 are arranged in the groove 6 and fixed by the fixing strap 7. The temperature control range of the temperature control system is 0°C to 300°C, and the accuracy is 0.5°C.

[0042] The fluid injection system includes a gas injection unit and an oil / water injection unit. The gas injection unit includes a gas cylinder 10, a pressure reducing valve 11, a first valve 12 and an inlet pipeline. The gas cylinder 10 and the pressure reducing valve 11 are connected to the first three-way valve 4 of the fluid phase change system through the first valve 12 and the inlet pipeline. The oil / water injection unit includes an oil / water pump 14, a valve and an oil / water pipeline 15. The oil / water pump 14 is connected to the first three-way valve 4 of the fluid phase change system through the valve and the oil / water pipeline 15. The volume of the oil / water pump 14 is 11 mL.

[0043] The pressure control system includes a pressure control pump 16, a buffer tank 17, valves, a four-way joint 18, a three-way joint 19, an evacuation unit and a vacuum unit. The pressure control pump 16 is connected to the buffer tank 17 through valves, the four-way joint 18, the three-way joint 19 and pipelines. The pressure control fluid is indium gallium alloy. The evacuation unit is an evacuation pipeline 23; the vacuum unit includes a vacuum pump 22, valves and pipelines. The evacuation unit and the vacuum unit are connected to the second three-way valve of the fluid phase change system. The volume of the pressure control pump 16 is 11 mL, and the volume of the buffer tank 17 is 5 mL.

[0044] The data acquisition system includes a pressure acquisition unit and an image acquisition unit. The pressure acquisition unit includes a pressure sensor 20, pipelines, data acquisition lines and a data recorder. The pressure sensor 20 is connected to the three-way joint 19 of the pressure control system through pipelines and connected to a data acquisition instrument 21 through data acquisition lines. The measuring range of the pressure sensor 20 is 0 - 200 MPa, and the accuracy is 0.05 MPa. The image acquisition unit includes a high-resolution camera 24, a cable 9 and a computer 25. The high-resolution camera 24 is used to photograph the gas-liquid distribution in the fused silica capillary 1, and the resolution of the camera photograph is 0.5 μm.

[0045] Example 2

[0046] The dew point test of the condensate gas sample is carried out using the experimental device of Example 1. The steps include:

[0047] (2-1) Use the vacuum pump 22 to evacuate the experimental device to remove the air in the experimental device. Open the gas cylinder 10, adjust the pressure reducing valve 11 to the set pressure, and inject condensate gas into the fluid phase change system to 5 MPa;

[0048] (2-2) Adjust the temperature control panel 8 to raise the temperature of the high and low temperature control console 5 to 120 °C;

[0049] (2-3) Use the pressure control pump 16 to inject the pressure control fluid into the fluid phase change system, adjust the first three-way valve 4 and the second three-way valve at both left and right to make the gas all located in the groove 6 of the high and low temperature control platform, and increase the pressure in the fluid phase change system to 55 MPa;

[0050] (2-4) Observe and record the fluid in the fused silica capillary 1 using a high-resolution camera 24. Lower or raise the pressure in the fluid phase change system. When the temperature and pressure at which the liquid phase begins to appear in the fused silica capillary 1 are the dew point conditions;

[0051] (2-5) Change the temperature set value described in step (2-2) to 160 °C, and repeat step (2-4). The new dew point conditions obtained are (160.5 °C, 40.8 MPa).

[0052] Example 3

[0053] Use the experimental device of Example 1 to conduct a bubble point test on the condensate oil sample. The steps include:

[0054] (3-1) Use a vacuum pump 22 to evacuate the experimental device to remove the air in the experimental device. Subsequently, use an oil injection / water pump 14 to inject 100 μL of condensate oil into the fluid phase change system;

[0055] (3-2) Use a pressure control pump 16 to inject a pressure control fluid into the fluid phase change system. Adjust the first three-way valve 4 and the second three-way valve on both sides to make the condensate oil located in the groove 6 of the high and low temperature control platform. Adjust the temperature control panel 8 to raise the temperature of the high and low temperature console 5 to 60 °C; detect the pressure in the device through the pressure acquisition unit and increase the pressure to 45 MPa;

[0056] (3-3) Observe and record the fluid in the fused silica capillary 1 using a high-resolution camera 24. Lower the pressure in the fluid phase change system. When the temperature and pressure at which the gas phase begins to appear in the fused silica capillary 1 are the bubble point conditions (60.7 °C, 36.2 MPa);

[0057] (3-4) Change the temperature set value described in step (B2) to 75 °C, and repeat step (3-3). The new bubble point conditions obtained are (75.6 °C, 43.1 MPa).

[0058] Example 4

[0059] Use the experimental device of Example 1 to conduct a fluid PVT relationship and liquid volume test. The steps include:

[0060] (4-1) Use a vacuum pump 22 to evacuate the experimental device to remove the air in the experimental device. Use an oil injection / water pump 14 to inject 50 μL of condensate oil into the fluid phase change system. Then open the gas cylinder 10 and adjust the pressure reducing valve 11 to 4 MPa to inject gas into the fluid phase change system;

[0061] (4-2) Inject pressurized fluid into the fluid phase change system using a pressure control pump 16, and adjust the first three-way valve 4 and the second three-way valve on both the left and right sides to make the oil-gas mixture located in the groove 6 of the high and low temperature control platform. Adjust the temperature control panel 8 to increase the temperature of the high and low temperature control console 5 to 125 °C; detect the pressure inside the device through the pressure acquisition unit, and increase the pressure to 45 MPa;

[0062] (4-3) Use a high-resolution camera 24 to observe and record the fluid in the fused silica capillary 1, and reduce the pressure inside the fluid phase change system. Calculate the oil phase volume according to the distributions of the oil / water phase and gas phase in the fused silica capillary 1 and the gas phase volume to obtain the PVT relationship and gas-liquid ratio of the fluid When the temperature is 124.8 °C, the pressure is 29.4 MPa, and the gas-liquid ratio is 3.87.

[0063] In this article, specific examples are used to elaborate on the principles and implementation methods of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An experimental device for measuring fluid phase characteristics, characterized in that: The experimental device is used for PVT analysis, and includes a fluid phase change system, a temperature control system, a fluid injection system, a pressure control system and a data acquisition system; The fluid phase change system comprises a fused capillary quartz tube, and the fused capillary quartz tube is used to contain the fluid to be tested for phase change; The temperature control system is connected to the fluid phase change system and is used to control the temperature of the fluid phase change system; The fluid injection system is connected to the fluid phase change system and is used to inject the fluid to be tested into the fluid phase change system; The pressure control system is connected to the fluid phase change system and is used to control the volume and pressure of the fluid to be measured in the fluid phase change system; The pressure control system includes a pressure control pump and a buffer tank. The pressure control pump is used to inject a pressure control fluid into the fluid phase change system, thereby controlling the volume and pressure of the fluid to be measured; the buffer tank is used to buffer the injection of the pressure control fluid; The data acquisition system is used to obtain the phase state and PVT data of the fluid to be tested in the fluid phase change system.

2. The experimental device for measuring the phase characteristics of a fluid as claimed in claim 1, characterized in that: The fluid phase change system also includes a connecting pipe, a first three-way valve and a second three-way valve; The fused capillary quartz tube is inserted into the connecting pipe and sealed with epoxy resin glue; the first three-way valve and the second three-way valve are respectively connected to the two ends of the connecting pipe to control the entry or discharge of the fluid to be measured.

3. The experimental device for measuring the phase characteristics of a fluid as claimed in claim 2, characterized in that: The temperature control system includes a high and low temperature control console, a groove, a fixing strap and a temperature control panel; The high and low temperature control console is used to accommodate a circulating fluid for heating or cooling, thereby controlling the temperature of the fused capillary quartz tube embedded in the groove; The groove is used to accommodate heat conductive material; The fixing tie is used to fix the fused capillary quartz tube in the groove; The temperature control panel is used to set the flow rate and temperature of the circulating fluid, thereby controlling the temperature of the high and low temperature control consoles.

4. The experimental device for measuring the phase characteristics of a fluid as claimed in claim 3, characterized in that: The fluid injection system comprises an air injection unit and an oil / water injection unit; the fluid to be tested comprises the air of the air injection unit and the oil / water of the oil / water injection unit; The gas injection unit comprises a gas cylinder, a pressure reducing valve, a first valve and an air inlet pipeline; the gas cylinder and the pressure reducing valve are connected to the first three-way valve of the fluid phase change system through the first valve and the air inlet pipeline; The oil / water injection unit includes an oil / water injection pump, a second valve and an oil / water injection pipeline; the oil / water injection pump is connected to the first three-way valve of the fluid phase change system through the second valve and the oil / water injection pipeline.

5. The experimental device for measuring the phase characteristics of a fluid as claimed in claim 4, characterized in that: The pressure control system further includes a third valve, a four-way connector, a three-way connector, an exhaust unit and a vacuum unit; The pressure control pump is connected to the buffer tank through the third valve, the four-way joint, the three-way joint and a pipeline; the other two ends of the four-way joint are connected to the first three-way valve and the second three-way valve respectively, and the pressure control fluid is mercury or indium gallium alloy; The vacuum unit includes a vacuum pump, a fourth valve and a pipeline; The evacuation unit and the vacuum unit are connected to the second three-way valve of the fluid phase change system.

6. The experimental device for measuring the phase characteristics of a fluid as claimed in claim 5, characterized in that: The data acquisition system includes a temperature and pressure acquisition unit and an image acquisition unit; A pressure sensor is provided in the pressure acquisition unit, and the pressure sensor is connected to the three-way joint of the pressure control system through a pipeline, and is connected to the data acquisition instrument through a data acquisition line; The image acquisition unit comprises a high-resolution camera; the high-resolution camera is used to photograph the gas-liquid distribution of the fluid to be measured in the molten capillary quartz tube.

7. An experimental method for determining the phase characteristics of a fluid, characterized in that: The experimental method uses the experimental device for measuring the phase characteristics of the fluid as described in any one of claims 1-6, and the experimental method includes a gas dew point test method, a liquid bubble point test method, a fluid PVT relationship and a liquid volume test method.

8. The experimental method for measuring the phase characteristics of a fluid as claimed in claim 7, characterized in that: The gas dew point test method comprises the following steps: (A1) Use a vacuum pump to evacuate the experimental device to remove the air in the experimental device; open the gas cylinder, adjust the pressure reducing valve to the set pressure, and inject gas into the fluid phase change system; (A2) injecting a pressure-controlled fluid into the fluid phase change system using a pressure-controlled pump, and adjusting the first three-way valve and the second three-way valve at the left and right positions so that all the gas is located in the transparent section of the fused capillary quartz tube; (A3) Adjust the temperature control panel to raise the temperature of the high and low temperature control consoles to the set value; (A4) using a high-resolution camera to observe and record the fluid in the molten quartz capillary tube, lowering or raising the pressure, and the temperature and pressure at which the liquid phase begins to appear in the molten quartz capillary tube is the dew point condition; (A5) Changing the temperature setting value in step (A3), repeating step (A4) to obtain multiple dew point conditions.

9. The experimental method for measuring the phase characteristics of a fluid as claimed in claim 7, characterized in that: The liquid bubble point test method comprises the following steps: (B1) Using a vacuum pump to evacuate the experimental device to remove the air in the experimental device; then, using an oil / water injection pump to inject a certain volume of oil / water into the fluid phase change system; (B2) injecting a pressure-controlled fluid into the fluid phase change system using a pressure-controlled pump, adjusting the first three-way valve and the second three-way valve at the left and right positions so that the oil / water is located in the transparent section of the molten capillary quartz tube; adjusting the temperature of the fluid phase change system through a temperature control panel; (B3) using a high-resolution camera to observe and record the fluid in the molten quartz capillary tube, repeatedly lowering and raising the pressure in the fluid phase change system, and the temperature and pressure at which the gas phase begins to appear in the molten quartz capillary tube is the bubble point condition; (B4) Changing the temperature setting value in step (B2) and repeating step (B3) to obtain multiple bubble point conditions.

10. The experimental method for measuring the phase characteristics of a fluid according to claim 7, characterized in that: The fluid PVT relationship and liquid volume test method includes the following steps: (C1) Using a vacuum pump to evacuate the experimental device to remove the air in the experimental device; using an oil / water injection pump to inject a certain volume of oil / water into the fluid phase change system; then opening the gas cylinder, adjusting the pressure reducing valve to the set pressure, and injecting gas into the fluid phase change system; (C2) injecting a pressure-controlled fluid into the fluid phase change system using a pressure-controlled pump, adjusting the first three-way valve and the second three-way valve at the left and right positions so that the oil / water and gas mixture is located in the transparent section of the molten capillary quartz tube; detecting the temperature and pressure in the device through a temperature and pressure acquisition unit, and adjusting the temperature and pressure of the fluid phase change system to the set value; (C3) using a high-resolution camera to observe and record the fluid in the molten capillary quartz tube, repeatedly reducing and increasing the pressure in the fluid phase change system; calculating the oil phase volume and gas phase volume based on the collected distribution of the oil / water phase and gas phase in the molten capillary quartz tube, respectively, to obtain the PVT relationship and gas-liquid ratio of the fluid; (C4) Changing the temperature setting value in step (C2), repeating step (C3), and obtaining multiple fluid PVT relationships and liquid volume conditions.

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