A pulse decay method liquid measurement permeability device

Abstract

The present application relates to the technical fields of reservoir porosity and permeability experiment, and especially relates to a liquid permeability measuring device based on pulse attenuation method. The liquid permeability measuring device based on pulse attenuation method comprises an upstream chamber and a downstream chamber installed at the front and back ends of a core holder, the upstream chamber and the downstream chamber form a pressure difference at the front and back ends of the core holder by injecting liquid through a liquid supply device, an adjusting tube is arranged on the outlet pipeline of the upstream chamber, a movable piston is arranged in the adjusting tube, and the piston moves in the adjusting tube through a control motor; the two ends of the core holder are connected with a pressure difference sensor, and the pressure difference sensor and the control motor are connected with a main control program to adjust the pressure difference at the front and back ends of the core holder. The liquid permeability measuring device based on pulse attenuation method has the advantages that the adjusting tube and the piston are arranged, the control motor connected with the main control program moves the piston to change the pressure difference at the front and back ends of the core holder, and the control precision and the automation degree are high. The liquid discharge and liquid supplement operations are not needed, and the liquid consumption is small.

Description

Technical Field

[0001] This invention relates to the field of reservoir porosity and permeability testing technology, and in particular to a pulse decay method liquid permeability measurement device. Background Technology

[0002] Shale and tight sandstone are unconventional rocks. The pores within shale and tight sandstone reservoirs are primarily nanoscale, resulting in low porosity and low permeability. In actual oilfield development, permeability is a key parameter for selecting favorable target areas, evaluating reservoirs, and predicting production capacity in shale and tight sandstone. Therefore, permeability measurement of shale and tight sandstone is necessary. Current technology typically uses the pulse decay method to measure the permeability of target lithology. This involves saturating both ends of the core sample with a liquid at a certain pressure until the pressure stabilizes. Then, the pressure at the downstream end of the core is reduced, and the pressure at both ends is allowed to re-equilibrate. The pressure changes and the time to re-equilibrate are recorded, and this process is repeated. Based on the recorded data, a relationship between the equilibrated pressure at both ends and the time taken is established to calculate the permeability of the target core sample. In existing equipment, after the pressure at the upstream and downstream ends of the core is balanced, the downstream pressure is reduced by draining the liquid. However, this method cannot precisely control the amount of liquid drained, resulting in low testing accuracy. Furthermore, the control process relies on manual operation of the drain valve, leading to low automation. Additionally, adjusting the pressure difference between the upstream and downstream ends of the target core requires repeated draining, necessitating constant replenishment during the experiment, resulting in high liquid consumption. Therefore, to address these shortcomings, a pulse decay method liquid permeability measurement device is proposed. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a pulse decay method liquid permeability measurement device, which solves the problems of low testing accuracy and low automation in existing experimental tools when measuring the permeability of shale and tight sandstone cores.

[0004] (II) Technical Solution To address the above problems, this invention provides a pulse decay method liquid permeability measurement device, comprising: A core is installed inside a core holder. The core holder has an upstream chamber and a downstream chamber at its front and rear ends, respectively. The inlets of the upstream and downstream chambers are connected to the outlets of a liquid supply device via pipes. The outlets are connected to the front and rear ends of the core holder, respectively, creating a pressure difference by applying the liquid pressure from the upstream and downstream chambers to the front and rear ends of the core holder. A differential pressure sensor is connected in parallel to the outside of the core holder to measure the pressure difference between the front and rear ends. An adjusting pipe is installed on the pipe connecting the inlet end of the core holder to the upstream chamber. Inside the adjusting pipe is a piston whose size matches the adjusting pipe and can move back and forth along the adjusting pipe. Moving the piston adjusts the pressure at the inlet end of the core holder. A control motor is installed at the end of the adjusting pipe. The output end of the control motor is connected to the piston, which pushes and pulls along the adjusting pipe. The control motor and the differential pressure sensor are simultaneously connected to the field main control program.

[0005] Preferably, the core holder is provided with a pressurizing device, and the output end of the pressurizing device is connected to the core holder through a pressure pipe to pressurize the core holder.

[0006] Preferably, a first pressure sensor is provided on the downstream chamber, and a second pressure sensor is provided on the pressure pipeline.

[0007] Preferably, the inlets of the upstream chamber and the downstream chamber are connected to the outlet of the liquid supply device, and the outlet of the liquid supply device is equipped with a main inlet valve.

[0008] Preferably, the inlet pipe of the downstream chamber is connected to the inlet pipe of the upstream chamber, and a connecting valve is provided on the inlet pipe of the downstream chamber.

[0009] Preferably, a downstream chamber switch valve is provided before the inlet of the downstream chamber, an upstream chamber inlet valve is provided before the inlet of the upstream chamber, an upstream chamber outlet valve is provided at the inlet end of the core holder, and a drain pipe is provided after the downstream chamber switch valve, with a drain valve on the drain pipe.

[0010] Preferably, an upstream buffer chamber is provided between the upstream chamber inlet and the liquid supply device, the inlet of the upstream buffer chamber is connected to the outlet of the liquid supply device, the outlet of the upstream buffer chamber is connected to the inlet of the upstream chamber, and the upstream chamber inlet valve is installed between the upstream chamber and the upstream buffer chamber.

[0011] Preferably, a downstream buffer chamber is provided between the downstream chamber inlet and the liquid supply device, the inlet pipe of the downstream chamber is connected to the inlet end of the downstream buffer chamber, the downstream chamber inlet is connected to the outlet of the downstream buffer chamber, a drain pipe is provided at the bottom end of the downstream buffer chamber, and a drain valve is installed on the drain pipe.

[0012] (III) Beneficial Effects The pulse decay method liquid permeability measurement device provided by this invention features an adjusting pipe with a piston inside, located on the pipeline between the upstream chamber and the inlet. A control motor connected to a main control program moves the piston, changing the liquid volume on one side of the upstream chamber of the core holder. This change in liquid volume creates a pressure difference between the upstream and downstream ends of the core holder. The piston's movement during adjustment is controlled by the main control program based on the real-time pressure difference between the upstream and downstream ends of the core holder, resulting in high control accuracy and automation. Furthermore, no draining or replenishing operations are required when adjusting the pressure difference between the two ends of the core, leading to low liquid consumption and low experimental costs. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the pulse attenuation method liquid permeability measurement device of the present invention; Figure 2 This is a schematic diagram of the pulse decay method liquid permeability measurement device of the present invention after the buffer chamber is installed.

[0014] The components include: 1. Main inlet valve; 2. Connecting valve; 3. Upstream chamber inlet valve; 4. Upstream chamber outlet valve; 5. Downstream chamber switch valve; 6. Drain valve; 7. Piston; 8. Differential pressure sensor; 9. First pressure sensor; 10. Core holder; 11. Core; 12. Upstream chamber; 13. Downstream chamber; 14. Second pressure sensor; 15. Pressurization device; 16. Control motor; 17. Upstream buffer chamber; 18. Downstream buffer chamber. Detailed Implementation

[0015] 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.

[0016] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0017] like Figure 1-2As shown, the pulse attenuation method liquid permeability measurement device provided by the present invention includes a core 11 installed inside a core holder 10. The core 11, as the target to be measured, is typically an unconventional rock with low porosity and low permeability, such as shale or dense sandstone. The core holder 10 serves as the main experimental site, used to install the core 11. After the core 11 is in place, pressure is applied to both ends of the core holder 10 using liquid, which transmits the liquid pressure to both ends of the core 11.

[0018] An upstream chamber 12 and a downstream chamber 13 are respectively provided at the front and rear ends of the core holder 10. The inlets of the upstream chamber 12 and the downstream chamber 13 are connected to the outlet of the liquid supply device through pipes, and the outlets are respectively connected to the front and rear ends of the core holder 10. The liquid pressure in the upstream chamber 12 and the downstream chamber 13 acts on the front and rear ends of the core holder 10 to form a pressure difference. At the beginning of the experiment, it is necessary to establish a stable pressure at the front and rear ends of the core holder 10. At this time, liquid is injected into the upstream chamber 12 and the downstream chamber 13 through the liquid supply device. The pressure of the liquid acts on the front and rear ends of the core holder 10 through the outlets of the upstream chamber 12 and the downstream chamber 13, respectively. At this time, the pressure difference between the front and rear ends of the core holder 10 is the pressure difference of the liquid inside the upstream chamber 12 and the downstream chamber 13. In order to measure the pressure difference between the front and rear ends of the core holder 10 in real time, a differential pressure sensor 8 is usually installed in parallel outside the core holder 10. The two measuring contacts of the differential pressure sensor 8 are respectively installed at the front and rear ends of the core holder 10 to measure the pressure difference between the front and rear ends of the core holder 10.

[0019] The core holder 10 is equipped with a pressurizing device 15. The output end of the pressurizing device 15 is connected to the core holder 10 via a pressure pipe to pressurize the interior of the core holder 10. The pressurizing device 15 can directly inject pressure into the core holder 10 and act on the core 11, making the environment in which the core 11 is located during the experiment similar to the high-pressure environment underground. This makes the data measured in the experiment closer to the actual values ​​of the core under test in the underground working environment, thereby improving the accuracy of the experimental results.

[0020] It should be noted that a first pressure sensor 9 is installed on the downstream chamber 13, and a second pressure sensor 14 is installed on the pressure pipeline. The first pressure sensor 9 is mainly used to measure the liquid pressure in the downstream chamber 13. Since the differential pressure sensor 8 is always operational during operation, the liquid pressure in the upstream chamber 12 can be calculated from the readings of the first pressure sensor 9 and the differential pressure sensor 8, facilitating pressure reading and adjustment at various locations within the device during operation. Similarly, the first pressure sensor 9 can also be installed on the upstream chamber 12 and used in conjunction with the reading of the differential pressure sensor 8 to read the liquid pressure in the downstream chamber 13. To improve the accuracy of the device readings, a pressure sensor can be installed on both the upstream chamber 12 and the downstream chamber 13 for pressure measurement and reading. The second pressure sensor 14 is used to measure the pressure applied by the pressurizing device 15 inside the core holder 10. During operation, the output power of the pressurizing device 15 is adjusted based on the reading of the second pressure sensor 14 to ensure that the pressure inside the core holder 10 meets the experimental requirements.

[0021] In this invention, an adjusting pipe is provided on the pipe connecting the inlet end of the core holder 10 to the upstream chamber 12. A piston 7, with dimensions matching the adjusting pipe and capable of moving back and forth along it, is installed inside the adjusting pipe. Moving the piston 7 within the adjusting pipe adjusts the pressure at the inlet end of the core holder 10. When measuring the permeability of shale or tight sandstone using the pulse decay method, it is necessary to change the pressure at both ends of the core holder 10 to create a pressure difference, wait for the pressure to reach equilibrium, and record the equilibrium pressure and the time taken to reach equilibrium. After repeating this process multiple times, the permeability of the core 11 being measured is calculated based on the recorded data and the volume of liquid at both ends of the core holder 10. At this point, the volume of liquid at both ends of the core holder 10 is the volume of the upstream chamber 12 and the downstream chamber 13. When piston 7 moves within the adjusting tube, it drives the liquid flow within the tube. As piston 7 moves towards the upstream chamber 12, it pushes the liquid in the adjusting tube towards the upstream chamber 12, increasing the liquid pressure and creating a pressure difference with the downstream chamber. Similarly, when piston 7 moves away from the upstream chamber 12, the total volume of liquid in the adjusting tube and the upstream chamber increases, decreasing the liquid pressure in the upstream chamber 12. During operation, depending on the requirements, the adjusting tube and piston 7 can also be installed on the outlet pipe of the downstream chamber 13 to create a pressure difference between the front and rear ends of the core holder 10 by adjusting the pressure in the downstream chamber 13. This method of changing the liquid pressure by moving piston 7 to create a pressure difference is simpler to operate than the existing method of creating a pressure difference by discharging liquid. Furthermore, the liquid pressure changes immediately after piston 7 moves, resulting in a fast response and easy adjustment. No liquid needs to be added to the device during adjustment, leading to lower testing costs.

[0022] The adjusting tube is equipped with a control motor 16 at its end. The output of the control motor 16 is connected to the piston 7, which pushes and pulls along the adjusting tube. The control motor 16 and the differential pressure sensor 8 are both connected to the main control program. The main control program can change the output of the control motor 16 to precisely move the position of the piston 7. After the main control program is connected to the differential pressure sensor 8, it can read the reading of the differential pressure sensor 8 in real time. When moving the piston 7, only the preset differential pressure needs to be input into the main control program. The main control program will determine the direction of movement of the piston 7 based on the differential pressure and start the control motor 16 to move the piston 7. At the same time, it will adjust the position of the piston 7 based on the reading of the differential pressure sensor 8. When the reading of the differential pressure sensor 8 is less than the set differential pressure, the piston 7 continues to move to compress the internal liquid; otherwise, the piston 7 moves to increase the volume of liquid in the adjusting tube. This realizes the automatic adjustment of the differential pressure at both ends of the core holder 10, improving the automation level and adjustment accuracy of the device. Compared with the traditional method of adjusting the pressure difference by switching valves to drain fluid, the method of adjusting the pressure difference by moving piston 7 to adjust the pressure difference at both ends of core holder 10 has higher accuracy after being connected and coordinated with the control program. This is because the control signal and pressure difference change are not delayed due to the time taken for valve opening and closing.

[0023] In this invention, to better control the pressure stability and liquid flow in and out of the upstream chamber 12 and downstream chamber 13, the inlets of the upstream chamber 12 and downstream chamber 13 are connected to the outlet of the liquid supply device, and the outlet of the liquid supply device is equipped with a main inlet valve 1. Only after the main inlet valve 1 is opened can the liquid flow into the upstream chamber 12 and downstream chamber 13 through the pipeline. The inlet pipe of the downstream chamber 13 is connected to the inlet pipe of the upstream chamber 12, and a connecting valve 2 is provided on the inlet pipe of the downstream chamber 13. When water injection begins, the connecting valve 2 is opened, and liquid flows into the upstream chamber 12 and downstream chamber 13 through the pipeline. When the liquid pressure in the downstream chamber 13 reaches the predetermined pressure, the connecting valve 2 is closed. At this time, liquid continues to be injected into the upstream chamber 12, causing the pressure in the upstream chamber 12 to continue to increase. This creates a pressure difference between the upstream chamber 12 and downstream chamber 13 during the initial injection process. The reading of the differential pressure sensor 8 is recorded at this time, and the time taken for the pressure at both ends of the core holder 10 to reach equilibrium is recorded. This data can be used as the first set of calculation data for the experimental process.

[0024] The downstream chamber 13 is equipped with a downstream chamber switch valve 5 before its inlet, the upstream chamber 12 is equipped with an upstream chamber inlet valve 3 before its inlet, and the core holder 10 is equipped with an upstream chamber outlet valve 4 at its inlet. A drain pipe with a drain valve 6 is located after the downstream chamber switch valve 5. The upstream chamber inlet valve 3 and the upstream chamber outlet valve 4 control the flow of liquid within the upstream chamber 12. Opening the upstream chamber inlet valve 3 allows the liquid supplied by the liquid supply device to be injected into the upstream chamber 12 through the pipe. The upstream chamber outlet valve 4 controls the flow of liquid from the upstream chamber 12 into the core holder 10. Opening the upstream chamber outlet valve 4 allows the liquid in the upstream chamber 12 to flow towards the inlet of the core holder 10 under hydraulic pressure. When injecting liquid, the liquid is injected into the downstream chamber 13 through the downstream chamber switch valve 5. After the experiment, the liquid in the device needs to be discharged. At this time, the downstream chamber switch valve 5, the upstream chamber outlet valve 4 and the drain valve 6 are opened. At this time, the liquid in the upstream chamber 12 will flow into the downstream chamber 13 through the core holder 10 and move with the liquid in the downstream chamber 13 to be discharged from the drain pipe.

[0025] like Figure 2 As shown, to improve the pressure stability in the upstream chamber 12 and the downstream chamber 13, an upstream buffer chamber 17 can be provided between the inlet of the upstream chamber 12 and the liquid supply device, and a downstream buffer chamber 18 can be provided between the inlet of the downstream chamber 13 and the liquid supply device. In this case, the inlet of the upstream buffer chamber 17 is connected to the outlet of the liquid supply device, and the outlet of the upstream buffer chamber 17 is connected to the inlet of the upstream chamber 12. An upstream inlet valve 3 is installed between the upstream chamber 12 and the upstream buffer chamber 17. The inlet pipe of the downstream chamber 13 is connected to the inlet end of the downstream buffer chamber 18, and the inlet of the downstream chamber 13 is connected to the outlet of the downstream buffer chamber 18. A drain pipe is provided at the bottom of the downstream buffer chamber 18, and a drain valve 6 is installed on the drain pipe. When liquid is injected into the upstream chamber 12 and downstream chamber 13 at the beginning of the experiment, the liquid first flows into the upstream buffer chamber 17 and downstream buffer chamber 18, where a certain hydraulic pressure is formed. Then, it flows into the upstream chamber 12 and downstream chamber 13. Normally, the volume of the upstream buffer chamber 17 and downstream buffer chamber 18 is much larger than that of the upstream chamber 12 and downstream chamber 13. At the start of operation, the upstream chamber inlet valve 3 and the downstream chamber switch valve 5 are closed. At this time, the entire operating procedure of the device is the same as when the upstream buffer chamber 17 and downstream buffer chamber 18 are not installed.

[0026] After several rebalancing of the pressure at both ends of the core holder 10, the approximate range of the voids in the measured core 11 can be determined based on the calculation results. If the calculation results show that the void volume in the target core 11 is much larger than that in conventional shale and dense sandstone, continuing to use the upstream chamber 12 and the downstream chamber 13 for the experiment will result in the pressure change rate at both ends of the core holder 10 being too fast due to the small liquid volume in the upstream chamber 12 and the downstream chamber 11, which will increase the error of the experimental results. At this time, open the downstream chamber switch valve 5 and the upstream chamber inlet valve 3 to connect the upstream chamber 12 with the upstream buffer chamber 17 and the downstream chamber 14 with the downstream buffer chamber 18, increasing the liquid volume at the front and rear ends of the core holder 10. Due to the increase in liquid volume, the hydraulic pressure at both ends of the outlet and inlet of the core holder 10 becomes more stable, slowing down the rate of pressure change at both ends of the core holder 10 during the experiment. Then, adjust the pressure difference at both ends of the core holder 10 and record the time taken for pressure equilibrium. At this time, the liquid volume used to calculate the permeability based on the recorded data is the total volume of the upstream chamber 12 and the upstream buffer chamber 17, as well as the total volume of the downstream chamber 13 and the downstream buffer chamber 18.

[0027] The pulse decay method liquid permeability measurement device provided by this invention can solve the problems of low accuracy and low automation in existing experimental tools when measuring the permeability of shale and tight sandstone cores. The specific operation process of the device is as follows: Step 1: Install the core onto the core holder and inject water into the device to create a pressure difference between the front and rear ends of the core holder. During this process, first open the main inlet valve, connecting valve, upstream chamber inlet valve, and downstream chamber switch valve. Once the pressure in the downstream chamber reaches the target pressure, close the connecting valve and downstream chamber switch valve to stop injecting water into the downstream chamber. Continue injecting water into the upstream chamber until the differential pressure sensor reading reaches the predetermined pressure difference. Then, close the main inlet valve and upstream chamber inlet valve. At this point, a pressure difference is created between the front and rear ends of the core holder.

[0028] Step 2: Wait for the differential pressure sensor reading to return to zero, and record the time taken and the equilibrium pressure. At this time, under the action of the differential pressure, the liquid in the upstream chamber gradually flows through the pores in the core to the downstream chamber, so that the pressure at both ends of the core holder is balanced.

[0029] Step 3: Move the piston to increase the pressure in the upstream chamber, creating a pressure difference between the front and rear ends of the core holder. During this process, the piston moves within the adjusting tube, compressing the volume of liquid in the upstream chamber and increasing its pressure, thus creating a pressure difference between the two ends of the core holder.

[0030] Step 4: Repeat steps 2 and 3, and record the pressure difference and the time taken for each balancing.

[0031] Step 5: Based on the data recorded in Step 4, and in conjunction with the volumes of the upstream and downstream chambers, calculate the permeability of the target core.

[0032] Step Six: If the calculation results are normal, the experiment ends. If the experimental results show that the permeability is much higher than that of conventional shale and tight sandstone, open the upstream chamber inlet valve and the downstream chamber switch valve, and repeat the above steps. At this time, the upstream chamber buffer valve and the downstream chamber buffer valve are connected to the upstream and downstream chambers, making the pressure at the front and rear ends of the core holder more stable and slowing down the rate of change. When calculating the permeability, replace the upstream chamber volume in the original calculation process with the total volume of the upstream chamber and the upstream buffer chamber, and replace the downstream chamber volume with the total volume of the downstream chamber and the downstream buffer chamber, and then calculate the permeability of the target core.

[0033] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pulse decay method liquid permeability measurement device, characterized in that, include: A core (11) is installed inside a core holder (10); the core holder (10) has an upstream chamber (12) and a downstream chamber (13) at its front and rear ends, respectively. The inlets of the upstream chamber (12) and the downstream chamber (13) are connected to the outlet of a liquid supply device through pipes, and the outlets are connected to the front and rear ends of the core holder (10), respectively, so that the liquid pressure in the upstream chamber (12) and the downstream chamber (13) acts on the front and rear ends of the core holder (10) to form a pressure difference; a differential pressure sensor (8) is connected in parallel to the outside of the core holder (10) to measure the pressure of the core holder (11). 0) Pressure difference between the front and rear ends; The inlet end of the core holder (10) is connected to the upstream chamber (12) by a pipe with an outward adjustment pipe. The adjustment pipe is equipped with a piston (7) whose size matches the adjustment pipe and can move back and forth along the adjustment pipe. The position of the moving piston (7) in the adjustment pipe adjusts the pressure at the inlet end of the core holder (10); The end of the adjustment pipe is equipped with a control motor (16). The output end of the control motor (16) is connected to the piston (7) to push and pull the piston along the adjustment pipe. The control motor (16) and the differential pressure sensor (8) are connected to the field main control program at the same time.

2. The pulse decay method liquid permeability measurement device according to claim 1, characterized in that, The core holder (10) is provided with a pressurizing device (15) on the outside. The output end of the pressurizing device (15) is connected to the core holder (10) through a pressure pipe to pressurize the core holder (10).

3. The pulse decay method liquid permeability measurement device according to claim 2, characterized in that, The downstream chamber (13) is equipped with a first pressure sensor (9), and the pressure pipeline is equipped with a second pressure sensor (14).

4. The pulse decay method liquid permeability measurement device according to claim 3, characterized in that, The inlets of the upstream chamber (12) and the downstream chamber (13) are connected to the outlet of the liquid supply device, and the outlet of the liquid supply device is equipped with a main inlet valve (1).

5. The pulse decay method liquid permeability measurement device according to claim 4, characterized in that, The inlet pipe of the downstream chamber (13) is connected to the inlet pipe of the upstream chamber (12), and a connecting valve (2) is provided on the inlet pipe of the downstream chamber (13).

6. The pulse decay method liquid permeability measurement device according to claim 5, characterized in that, A downstream chamber switch valve (5) is provided in front of the inlet of the downstream chamber (13), an upstream chamber inlet valve (3) is provided in front of the inlet of the upstream chamber (12), an upstream chamber outlet valve (4) is provided at the inlet end of the core holder (10), a drain pipe is provided after the downstream chamber switch valve (5), and a drain valve (6) is provided on the drain pipe.

7. The pulse decay method liquid permeability measurement device according to claim 6, characterized in that, An upstream buffer chamber (17) is provided between the inlet of the upstream chamber (12) and the liquid supply device. The inlet of the upstream buffer chamber (17) is connected to the outlet of the liquid supply device, and the outlet of the upstream buffer chamber (17) is connected to the inlet of the upstream chamber (12). The upstream chamber inlet valve (3) is installed between the upstream chamber (12) and the upstream buffer chamber (17).

8. The pulse decay method liquid permeability measurement device according to claim 7, characterized in that, A downstream buffer chamber (18) is provided between the inlet of the downstream chamber (13) and the liquid supply device. The inlet pipe of the downstream chamber (13) is connected to the inlet end of the downstream buffer chamber (18). The inlet of the downstream chamber (13) is connected to the outlet of the downstream buffer chamber (18). A drain pipe is provided at the bottom of the downstream buffer chamber (18), and a drain valve (6) is installed on the drain pipe.

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