Porosity measuring apparatus and method

Abstract

The present application belongs to the technical field of geological survey, and particularly relates to a porosity determination device and method. The porosity determination device comprises: a skeleton volume testing unit for measuring the skeleton volume of a sample by a gas method, the skeleton volume testing unit comprising a first measuring chamber for accommodating the sample; and a total volume testing unit for measuring the total volume of the sample according to the principle of specific heat capacity ratio measurement by a vibration method, the total volume testing unit comprising a connected specific heat capacity ratio measurement assembly and a second measuring chamber, wherein the volume of the internal space of the second measuring chamber is the same as the volume of the internal space of the first measuring chamber, and the first measuring chamber is connected with the specific heat capacity ratio measurement assembly. In the present application, gas is used as the measurement medium, and the skeleton volume and the total volume of the sample can be integrally determined, thereby providing technical support for reducing the influence of human factors, improving error control ability and data comparability in the porosity determination process.

Description

Technical Field

[0001] This invention belongs to the field of geological surveying technology, and in particular relates to a porosity measuring device and method. Background Technology

[0002] The analysis, testing, and application of rock sample porosity are integral to the entire process of oil and gas exploration and development, serving as an indispensable parameter in oil and gas geological research. Over the years, various methods for determining (calculating) rock sample porosity have been developed. Currently, laboratory applications often employ different apparatuses, methods, and procedures to separately measure two parameters—total volume, framework volume, and pore volume—of the rock sample before calculating the porosity according to the definition of porosity. With the continuous expansion of oil and gas exploration and development, particularly the in-depth research on shale oil and gas exploration and development, the workload for porosity testing of mudstone, shale, and salt rock samples is increasing. The fragility, well-developed micropores, and water sensitivity of these rock types present new challenges to existing porosity testing methods.

[0003] In the laboratory determination of rock sample porosity, although the total volume, skeleton volume, and pore volume of the rock sample can be obtained through various methods to calculate the porosity, given the micropore development characteristics of shale, the determination of the total volume and skeleton volume is often preferred for porosity calculation. The determination of the rock sample skeleton volume mostly employs the gas method based on Boehringer-Marsteller's law. Nitrogen or helium can be used as the measuring medium; considering the micropore development of shale, helium is often preferred. Overall, the skeleton volume determination method is relatively mature, but its results are affected by operational factors such as equilibration time and system sealing, so its error has a significant impact on the accuracy of porosity determination. When the total volume of the rock sample is fixed and the nominal value of the rock sample skeleton volume is set, it is found that as the error in skeleton volume determination increases, the accuracy of porosity determination (calculation) decreases systematically. When the relative error of the skeleton volume reaches 1%, the absolute error in porosity determination (calculation) approaches 1.0; and when the relative error of the skeleton volume reaches 1.3%, the absolute error in porosity reaches 1.2.

[0004] Determining the total volume of a rock sample is another crucial step in rock sample porosity determination. Existing methods for determining the total volume of rock samples mainly include measurement, buoyancy, test tube level, and gas methods. In addition, variable density buoyancy and three-dimensional laser scanning imaging methods have attracted attention in the industry. The buoyancy method involves immersing the rock sample in a liquid after drying it. Under normal temperature and pressure conditions, when the sample is saturated with the measured medium, the weight of the rock sample in the liquid is measured, and the specific gravity of the liquid is determined. The rock sample is then removed from the liquid, the surface is wiped clean, and the weight of the sample in air is measured. The difference between the weight in air and in liquid, divided by the specific gravity of the liquid, yields the total volume of the rock sample. This method requires manual wiping of the liquid from the rock sample surface, making the results highly susceptible to human error. For granular rock samples, determining the total volume is difficult. The traditional measurement method involves using tools such as vernier calipers to measure the dimensions of the sample and then calculating the total volume. This method requires a high degree of precision in the shape and processing of the rock sample; only samples with regular shapes can achieve good results. Three-dimensional laser scanning imaging has attracted attention in recent years. According to articles such as Wei Yaqiang's "Combined Determination of Effective Porosity of Rocks by Three-Dimensional Laser Scanning and Gas Replacement," *Geological Science and Technology Information*, July 2015, and Chen Siyu's "The Influence of Tight Reservoir Sample Volume Measurement on Porosity Error," *Petroleum Experimental Geology*, November 2016, this method consists of a three-dimensional laser scanner and corresponding software system. By scanning the rock sample in three dimensions, a three-dimensional model of the rock sample is constructed. Specific software is used to obtain a three-dimensional image of the rock sample, and then the total volume of the rock sample is calculated. Studies show that the testing accuracy increases with the increase of scanning resolution, but the testing accuracy may differ for different rock samples at the same scanning resolution. Furthermore, from the perspective of its principle and process, the determination of the total volume of granular rock samples (rock cuttings) is difficult to achieve.

[0005] To overcome the shortcomings of the above methods, Chinese patent (application number 201310169226.X) provides a variable density buoyancy method. This method uses a magnetic fluid as the measuring medium. The rock sample is placed in the magnetic fluid, and the density of the magnetic fluid is adjusted under the influence of an electromagnetic field. The weight of the rock sample at the corresponding density in the magnetic fluid is then measured, and the total volume of the rock sample is calculated using the buoyancy formula. Preliminary practice has confirmed that the variable density buoyancy method has technical advantages such as less susceptibility to human factors, a short measurement cycle, and a wide range of applications, making it a promising new method for determining the total volume of rock samples. However, this method relies on the change in the weight of the rock sample in the magnetic fluid with the density of the magnetic fluid to determine the total volume of the rock sample. The weight of the rock sample in the magnetic fluid is a crucial parameter, and its accuracy directly affects the precision of the determination and calculation of the total volume of the rock sample. It should be noted that the variable density buoyancy method in this patent is developed based on the high-precision controllability of magnetofluid density. Magnetofluids are mainly composed of a matrix, magnetic particles, and surfactants. Regardless of whether the matrix is ​​water, kerosene, ester, or any other type of magnetofluid, it contains a certain amount of organic matter. When a rock sample is placed in it, organic matter adheres to the surface of the rock sample to a certain extent. In oil and gas exploration and development research, researchers often need to obtain multiple information such as physical properties and geochemistry from the same rock sample. There is even a need to perform organic geochemical testing after determining the total volume of the rock sample. From this perspective, the organic matter adhering to the surface of the rock sample during the total volume determination process is inconvenient for organic geochemical analysis after the total volume determination. Therefore, there is a strong need for a total volume determination method that can avoid the adhesion of organic matter to the rock sample to meet the requirements of subsequent testing.

[0006] Based on an analysis of the operational process of Chinese Patent (Application No. 201310169226.X), Chinese Patent (Application No. 201810471586.8) proposes a new process, device, and method for weighing in liquids, focusing on testing procedures, work efficiency, and testing accuracy. This further solidifies the foundation for accurately determining the total volume of rock samples using magnetic fluids. The literature "Research on Error Control Methods for Porosity Measurement" (Petroleum Experimental Geology, 2019) introduces a method for determining the volumetric density of rock samples, expanding the measurement medium from magnetic fluids to liquids such as water, kerosene, and anhydrous ethanol, achieving new progress in practicality.

[0007] Chinese Patent (Application No. 201610127214.4) discloses a rock porosity measuring device, which proposes an integrated technical solution for rock sample porosity testing. Its advantages are: (1) The measurement principle is based on Bohr's law, using the principle of gas method to determine the volume of rock skeleton. The volume of rock sample skeleton and the total volume of rock sample can be measured by vacuuming both sides of the sample once. (2) The latex sample sleeve used can be deformed arbitrarily, so there are no requirements for the shape of the sample. This changes the traditional porosity measurement process and brings convenience to the fully automatic measurement of porosity of rock samples with any irregular shape. (3) The opening and closing of all valves in the above device can be automatically realized by computer without manual operation. (4) The total volume of the latex sample sleeve will not change whether it is stretched or contracted under vacuum. Therefore, the deformation of the sample sleeve will not affect the measurement results, reducing the detection error.

[0008] Chinese Patent (Application No. 202010566444.7) discloses an accurate method for measuring the oil-water saturation of shale oil and gas reservoir rocks. The method includes: preparing a shale saturation sample from the center of a full-diameter shale rock to ensure the sample is not infiltrated by mud water; employing a rapid method for determining the total volume of frozen shale rock to ensure no cracks or fluid loss occur during the volume measurement process; measuring the total volume of the shale first, then the water-oil content, to ensure the oil-water saturation of the sample is not affected by cracks generated after the shale is dried; and using a distillation method to determine the water content of the shale sample without leaching with cooling reflux reagent, ensuring the accuracy of the water content determination by distillation extraction. This method significantly improves the accuracy of shale oil-water saturation testing and has a short testing cycle and high efficiency.

[0009] Furthermore, in some cases, given the weight of a substance, the problem of measuring its total volume can be transformed into a problem of measuring its density. The literature ("Measuring the Density of Substances Using a Gas Specific Heat Ratio Analyzer," *Experimental Technology and Management*, September 2009, Vol. 26, No. 9) proposes a method for measuring the density of soluble and hygroscopic substances using a gas specific heat ratio analyzer. Substances involved include white sugar, salt, anhydrous glycerol, millet, and red brick. The literature ("An Improvement of the Experiment for Measuring the Density of Soluble Substances Using Gas Specific Heat Ratio," *Physical Experiments*, August 2014, Vol. 34, No. 8) proposes an improved method for determining the density of substances using gas specific heat ratio. The literature ("An Improvement of the Experimental Method for Measuring the Gas Specific Heat Ratio Using Vibration," *Journal of Taizhou University*, December 2010, Vol. 32, No. 6) presents methods and precautions for obtaining accurate experimental data. Chinese patent (application number 201410517156) discloses a method for measuring the specific heat ratio of air by piston vibration inside a cylinder; Chinese patent (application number 201410585318.0) discloses a method for measuring the specific heat ratio of air by vibration; Chinese patent (application number 2014105853227) discloses an improved device for measuring the specific heat ratio of air by vibration; Chinese patent (application number 2018216918568) discloses a device for measuring the specific heat ratio of air that can improve experimental accuracy; Chinese patent (application number 201410585611.7) discloses an improved device for measuring the specific heat ratio of air by vibration; and Chinese patent (application number 201410517305.X) discloses a method for measuring the specific heat ratio of air by piston vibration inside a single-end sealed vertical cylinder. In the prior art, numerous methods and devices for measuring the specific heat ratio of air by vibration have been proposed from different perspectives and based on various needs. However, based on the descriptions in these documents and the experimental data, the measured parameters are more accurate when the experimental subjects are mainly particulate water-sensitive materials with non-porous characteristics, such as table salt and sugar. When the test subject is a porous material, the test deviation increases, for example, red brick, whose density was measured to be 3.712 g / cm³ in the literature. 3 This is different from the usual 1.8-2.3 g / cm³. 3 The discrepancy is significant. This indicates that for porous media such as rock samples, given the sample weight, determining the total volume can only be transformed into a bulk density test. Further research is needed to determine the volume or density of porous materials using the air specific heat ratio experiment.

[0010] In summary, rock sample porosity testing is characterized by the need for numerous equipment configurations, diverse measurement media types, and a multitude of auxiliary peripheral tools. There is significant room for improvement in areas such as the integration of testing devices, control of testing errors, reduction of the influence of human factors, and comparability of test data. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a porosity measuring device and method that uses gas as the measuring medium to integrate the measurement of the sample's skeletal volume and total volume, providing technical support for reducing the influence of human factors, improving error control capabilities, and enhancing data comparability during porosity measurement.

[0012] A first aspect of the present invention provides a porosity measuring device, comprising:

[0013] A skeleton volume testing unit for measuring the skeleton volume of a sample by a gas method, the skeleton volume testing unit comprising a first measuring chamber for containing the sample; and

[0014] The total volume testing unit is used to measure the total volume of the sample according to the principle of measuring specific heat ratio by vibration method. The total volume testing unit includes a specific heat ratio measuring component and a second measuring chamber connected together. The volume of the internal space of the second measuring chamber is the same as the volume of the internal space of the first measuring chamber. The first measuring chamber is connected to the specific heat ratio measuring component.

[0015] In one embodiment, the specific heat ratio measuring assembly includes a gas storage chamber, a vertical tube, a vibrator, and an elastic element.

[0016] The vertical pipe is located at the top of the gas storage chamber and communicates with the interior of the gas storage chamber. The elastic element and the vibrator are arranged sequentially from top to bottom inside the vertical pipe.

[0017] By introducing a measuring gas into the gas storage chamber, the oscillator can undergo simple harmonic motion under the action of its own weight, the elastic force of the elastic element, and the pressure of the measuring gas.

[0018] In one embodiment, the specific heat ratio measuring assembly further includes a vibration detection element and a first pressure detection element.

[0019] The vibration detection element is used to measure the simple harmonic motion of the oscillator;

[0020] The first pressure sensing element is used to measure the pressure inside the gas storage chamber.

[0021] In one embodiment, the total volume testing unit further includes a first gas source.

[0022] The outlet of the first gas source is connected to the specific heat ratio measuring component to provide measuring gas to the specific heat ratio measuring component.

[0023] In one embodiment, a buffer chamber is further provided between the first gas source and the specific heat capacity ratio measuring component.

[0024] A first pressure regulating valve is provided between the first gas source and the buffer chamber, and a second pressure regulating valve is provided between the buffer chamber and the specific heat capacity ratio measuring component.

[0025] In one embodiment, the skeleton volume testing unit includes a second gas source and a standard gas chamber.

[0026] The second gas source is connected in sequence to the standard gas chamber and the first measuring chamber.

[0027] A third pressure regulating valve is provided between the second gas source and the standard gas chamber, and a first valve is provided between the standard gas chamber and the first measuring chamber.

[0028] In one embodiment, the skeleton volume testing unit further includes a second pressure detection element and a third pressure detection element.

[0029] The second pressure sensing element is connected to the pipeline between the standard gas chamber and the first valve, and the third pressure sensing element is connected to the pipeline between the first valve and the first measuring chamber.

[0030] A second aspect of the present invention provides a method for measuring porosity, which uses the above-described porosity measuring device to measure the porosity of a rock sample, comprising the following steps:

[0031] Step 1: After placing the sample into the first measuring chamber, introduce a measuring gas at a preset pressure into the first measuring chamber so that the measuring gas diffuses into the pores of the sample. After the pressure stabilizes, record the equilibrium pressure P and calculate the skeleton volume V0 of the sample based on the pressure change of the measuring gas.

[0032] Step 2: Maintain the pressure inside the specific heat ratio measuring component at the equilibrium pressure P in step 1, and connect the second measuring chamber and the first measuring chamber to the specific heat ratio measuring component in sequence, so as to measure the total volume V of the sample according to the principle of measuring specific heat ratio by vibration method.

[0033] In one implementation, step 2 includes the following sub-steps:

[0034] Step 21: Connect the second measuring chamber to the specific heat ratio measuring component, continuously introduce measuring gas into the specific heat ratio measuring component, and keep the pressure in the specific heat ratio measuring component at the equilibrium pressure P. The oscillator in the vertical tube will perform simple harmonic motion under the action of the measuring gas.

[0035] Step 22: Detect the simple harmonic motion of the oscillator in Step 21 and obtain the initial oscillation period T0 of the oscillator;

[0036] Step 23: Disconnect the connection between the specific heat ratio measuring component and the second measuring chamber, and connect the specific heat ratio measuring component to the first measuring chamber. The oscillator in the vertical tube will undergo simple harmonic motion under the action of the measuring gas.

[0037] Step 24: Detect the simple harmonic vibration of the oscillator in Step 23, and obtain the vibration period T1 of the oscillator after loading the sample;

[0038] Step 25: Calculate the total volume V of the sample based on the initial vibration period T0 of the oscillator and the vibration period T1 after loading the sample.

[0039] In one embodiment, in step 6, the total volume V of the sample is calculated using the following formula:

[0040]

[0041] Where: r is the specific heat capacity ratio of the measured gas;

[0042] P is the equilibrium pressure;

[0043] d is the diameter of the oscillator;

[0044] T0 is the initial oscillation period of the oscillator;

[0045] T1 is the vibration period of the oscillator after the sample is loaded;

[0046] m is the mass of the oscillator.

[0047] Compared with the prior art, the advantages of the present invention are as follows:

[0048] (1) The porosity measuring device and method of the present invention uses gas as the measuring medium and adopts a combination of gas method and vibration method to measure the porosity of the sample. The skeleton volume and total volume of the sample can be tested in one sample loading, avoiding the risk of sample particles falling off during sample transfer, which helps to ensure testing efficiency and accuracy, and provides a high level of integration of porosity measuring device, which is convenient for maintenance and application.

[0049] (2) In this invention, during the measurement of the total volume of the sample, the equilibrium pressure is used as a constraint condition to make the gas pressure of the simple harmonic oscillation of the oscillator equal to the equilibrium pressure, thereby preventing the test gas from seeping into the pores of the sample, thus ensuring the stability of the simple harmonic oscillation period and ensuring the accuracy of the total volume of the sample calculation.

[0050] (3) In this invention, gas is used as the measuring medium to complete the determination of the skeleton volume and the total volume, which reduces the contamination of the sample and is beneficial to the subsequent analysis and testing of the rock sample. It overcomes the problems of water sensitivity and oil sensitivity of the sample when measuring the total volume with liquid as the measuring medium, expands the scope of application, and improves the service capability of rock sample porosity testing.

[0051] (4) In this invention, there are low restrictions on the sample morphology. Plunger, block, and granular rock samples can all be tested, which can meet more testing and research needs. Attached Figure Description

[0052] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0053] Figure 1 This is a schematic diagram of the porosity measuring device in one embodiment of the present invention;

[0054] Figure 2 This is a flowchart of the porosity measurement method of the present invention;

[0055] Figure label:

[0056] 1. Sample; 2. Specific heat ratio measuring assembly; 3. First measuring chamber; 4. Second measuring chamber;

[0057] 5. Primary gas source; 6. Buffer chamber; 7. Secondary gas source; 8. Standard gas chamber;

[0058] 9. Control and calculation unit; 10. First pressure regulating valve; 11. Second pressure regulating valve;

[0059] 12. Third pressure regulating valve; 13. First valve; 14. Second pressure sensing element;

[0060] 15. Third pressure sensing element; 16. Second valve; 17. Third valve;

[0061] 21. Gas storage chamber; 22. Vertical pipe; 23. Vibrator; 24. Elastic element;

[0062] 25. Vibration detection element; 26. First pressure detection element; 27. Top cover accessory. Detailed Implementation

[0063] The invention will now be further described with reference to the accompanying drawings.

[0064] like Figure 1 As shown, according to a first aspect of the present invention, the present invention provides a porosity measuring device, comprising: a skeleton volume measuring unit and a total volume measuring unit. The skeleton volume measuring unit is used to measure the skeleton volume of a sample 1 by a gas method, and the skeleton volume measuring unit includes a first measuring chamber 3 for containing the sample 1. The total volume measuring unit is used to measure the total volume of the sample 1 according to the principle of measuring specific heat ratio by vibration method, and the total volume measuring unit includes a connected specific heat ratio measuring component 2 and a second measuring chamber 4. The volume of the internal space of the second measuring chamber 4 is the same as the volume of the internal space of the first measuring chamber 3, and the first measuring chamber 3 is connected to the specific heat ratio measuring component 2.

[0065] When measuring the porosity of sample 1, the skeletal volume of sample 1 is first measured using the gas method and the skeletal volume testing unit. Then, the total volume of sample 1 is measured according to the principle of measuring specific heat ratio using the vibration method. Since the internal volume of the second measuring chamber 4 is the same as that of the first measuring chamber 3, the second measuring chamber 4 (without sample 1) is first connected to the specific heat ratio measuring component 2, and a vibration test is performed to obtain the vibration period before sample 1 is loaded, i.e., the initial vibration period. Then, the connection between the second measuring chamber 4 and the specific heat ratio measuring component 2 is disconnected, and the first measuring chamber 3 is connected to the specific heat ratio measuring component 2, and a vibration test is performed to obtain the vibration period after sample 1 is loaded. The total volume of sample 1 is calculated based on the initial vibration period and the vibration period after sample 1 is loaded.

[0066] In this invention, gas is used as the measuring medium, and the porosity of sample 1 is measured by a combination of gas method and vibration method. The skeleton volume and total volume of sample 1 can be tested in one sample loading, avoiding the risk of sample 1 particles falling off during sample 1 transfer, which helps to ensure testing efficiency and accuracy, and provides a high level of integration of porosity measuring device, which is convenient for maintenance and application.

[0067] During the measurement of the total volume of sample 1, the equilibrium pressure is used as a constraint condition to make the gas pressure of the simple harmonic oscillation of oscillator 23 equal to the equilibrium pressure, thus preventing the measuring gas from seeping into the pores of sample 1, thereby ensuring the stability of the simple harmonic oscillation period and ensuring the accuracy of the total volume calculation of sample 1.

[0068] Using gas as the measuring medium to determine the skeleton volume and total volume reduces the contamination of sample 1, which is beneficial for subsequent analysis and testing of rock samples. It overcomes the problems of water sensitivity and oil sensitivity of sample 1 when measuring the total volume of sample 1 using liquid as the measuring medium, expands the scope of application, and improves the service capability of rock sample porosity testing.

[0069] In this invention, there are few restrictions on the morphology of sample 1; plunger, block, and granular rock samples can all be tested, which can meet more testing and research needs.

[0070] It should be noted that the above-mentioned sample 1 in this invention is a porous material, such as rock sample 1.

[0071] The measuring gas in this invention can be nitrogen, air, or helium, etc.

[0072] Furthermore, preferably, the first measuring chamber 3 and the second measuring chamber 4 are made of the same material and have the same specifications, which is beneficial to improving the measurement accuracy.

[0073] Example 1

[0074] In this embodiment, the specific heat ratio measuring component 2 includes a gas storage chamber 21, a vertical tube 22, an oscillator 23, and an elastic element 24. The vertical tube 22 is disposed at the top of the gas storage chamber 21 and communicates with the interior of the gas storage chamber 21. The elastic element 24 and the oscillator 23 are disposed sequentially from top to bottom inside the vertical tube 22.

[0075] By introducing a measuring medium into the gas storage chamber 21, the oscillator 23 can undergo simple harmonic motion under the action of its own weight, the elastic force of the elastic element 24, and the pressure of the measuring gas.

[0076] The oscillator 23 is a cylindrical or spherical object. Furthermore, the oscillator 23 includes multiple (at least two) oscillators 23 with the same diameter and different densities (materials). Different oscillators 23 can be selected according to different equilibrium pressure conditions to meet the test requirements.

[0077] The first measuring chamber 3 and the second measuring chamber 4 are both connected to the gas storage chamber 21 via pipelines. A second valve 16 is installed between the second measuring chamber 4 and the gas storage chamber 21, and a third valve 17 is installed between the first measuring chamber 3 and the gas storage chamber 21.

[0078] The specific heat ratio measuring assembly 2 also includes a vibration detection element 25 and a first pressure detection element 26. The vibration detection element 25 is used to measure the simple harmonic vibration of the oscillator 23, and the first pressure detection element 26 is used to measure the pressure inside the gas storage chamber 21.

[0079] Specifically, the vibration detection element 25 can be a photoelectric counter, which can measure the vibration frequency of the oscillator 23. Combined with the vibration time, the vibration frequency and vibration period can be obtained.

[0080] The first pressure sensing element 26 can be a pressure sensor or a pressure gauge.

[0081] Specifically, the gas storage chamber 21 includes a first cup body and a first top cover, forming a sealed space between the first cup body and the first top cover for storing the measuring gas, thereby causing the oscillator 23 to perform simple harmonic motion under its own weight, the elastic force of the elastic element 24 and the pressure of the measuring gas.

[0082] More specifically, a top cover attachment 27 is provided on the top cover of the gas storage chamber 21. The top cover attachment 27 extends vertically and is hollow inside to communicate with the interior of the gas storage chamber 21. A first pressure detection element 26 is provided on the top cover attachment 27 to detect the pressure inside the gas storage chamber 21. A vibration detection element 25 is provided on the outer wall of the top cover attachment 27 to detect the vibration frequency of the oscillator 23.

[0083] Example 2

[0084] This embodiment describes the differences from the above embodiments, while the similarities will not be repeated.

[0085] In this embodiment, the total volume testing unit further includes a first gas source 5. The outlet of the first gas source 5 is connected to the specific heat ratio measuring component 2 to provide a measuring medium into the specific heat ratio measuring component 2.

[0086] Preferably, a buffer chamber 6 is provided between the first gas source 5 and the specific heat ratio measuring component 2, a first pressure regulating valve 10 is provided between the first gas source 5 and the buffer chamber 6, and a second pressure regulating valve 11 is provided between the buffer chamber 6 and the specific heat ratio measuring component 2.

[0087] The first gas source 5 provides the measuring gas, and the first pressure regulating valve 10 at its outlet adjusts the outlet pressure or flow rate to ensure uniform gas delivery. The buffer chamber 6 buffers the gas entering the comparative heat capacity ratio measuring component 2. Simultaneously, the second pressure regulating valve 11 at the outlet of the gas storage chamber precisely controls or regulates the gas entering the comparative heat capacity ratio measuring component 2, thereby controlling the pressure within the component. This allows the oscillator 23 in the vertical tube 22 to perform simple harmonic motion under stable gas pressure, thus improving the accuracy of the overall volume measurement of sample 1.

[0088] Example 3

[0089] This embodiment describes the differences from the above embodiments, while the similarities will not be repeated.

[0090] In this embodiment, the skeleton volume testing unit includes a second air source 7 and a standard air chamber 8. The second air source 7 is connected to the standard air chamber 8 and the first measuring chamber 3 in sequence. A third pressure regulating valve 12 is provided between the second air source 7 and the standard air chamber 8, and a first valve 13 is provided between the standard air chamber 8 and the first measuring chamber 3.

[0091] The second gas source 7 provides the measuring gas, and the third pressure regulating valve 12 at its outlet is used to adjust the outlet pressure or flow rate to ensure uniform gas delivery. Closing the first valve 13 and opening the third pressure regulating valve 12 allows gas at a preset pressure to be stored in the standard gas chamber 8. Once the gas in the standard gas chamber 8 reaches the preset pressure, the third pressure regulating valve 12 is closed, and the first valve 13 is opened, allowing the gas at the preset pressure in the standard gas chamber 8 to diffuse into the pores of the sample 1 in the first measuring chamber 3. After pressure equilibrium is reached, the equilibrium pressure is recorded, and the skeleton volume of the sample 1 is calculated based on the pressure change of the measuring gas.

[0092] It should be noted that the second gas source 7 and the first gas source 5 provide the same measuring gas.

[0093] Specifically, the skeleton volume testing unit also includes a second pressure sensing element 14 and a third pressure sensing element 15. The second pressure sensing element 14 is connected to the pipeline between the standard gas chamber 8 and the first valve 13, and the third pressure sensing element 15 is connected to the pipeline between the first valve 13 and the first measuring chamber 3. When the first valve 13 and the third pressure regulating valve 12 are closed, the pressure of the gas stored in the standard gas chamber 8, i.e., the initial pressure, can be detected by the second pressure sensing element 14. When the third pressure regulating valve 12 is closed and the first valve 13 is opened, the equilibrium pressure can be measured by the second pressure sensing element 14 and the third pressure sensing element 15. When the first valve 13 is closed, the pressure of the gas in the first measuring chamber 3 can be measured by the third pressure sensing element 15.

[0094] Furthermore, specifically, the first measuring chamber 3 includes a second cup and a second top cover, with a sealed space formed between the second cup and the second top cover. The second measuring chamber 4 includes a third cup and a third top cover, with a sealed space formed between the third cup and the third top cover.

[0095] Example 4

[0096] This embodiment describes the differences from the above embodiments, while the similarities will not be repeated.

[0097] In this embodiment, the porosity measuring device further includes a control and calculation unit 9. The control and calculation unit 9 is connected to the first pressure detection element 26, the second pressure detection element 14, the third pressure detection element 15, and the vibration detection element 25, respectively, to obtain the corresponding pressure data and vibration data, and calculate the skeleton volume and total volume of sample 1 based on the corresponding pressure data and vibration data, thereby obtaining the porosity of sample 1.

[0098] The control calculation unit 9 can also be connected to the first valve 13, the second valve 16, the third valve 17, the first pressure regulating valve 10, the second pressure regulating valve 11 and the third pressure regulating valve 12 mentioned above, so as to control the opening and closing and / or opening degree of the corresponding valves respectively, thereby realizing the automation of rock sample porosity testing, which is beneficial to error control and improving test accuracy.

[0099] Specifically, the control computing unit 9 can be a computer.

[0100] In this embodiment, the entire process of testing the rock sample skeleton volume, total volume, and calculating porosity is automated, avoiding the influence of human factors during the testing process and helping to ensure testing efficiency and accuracy.

[0101] like Figure 2 As shown in the second aspect of the present invention, the present invention also provides a method for measuring porosity, which uses the above-described porosity measuring device to measure the porosity of a rock sample, comprising the following steps:

[0102] Step 1: After placing sample 1 into the first measuring chamber 3, introduce a measuring medium with a preset pressure into the first measuring chamber 3 so that the measuring medium diffuses into the pores of sample 1. After the pressure stabilizes, record the equilibrium pressure P, and calculate the skeleton volume V0 of sample 1 based on the pressure change of the measuring medium.

[0103] Step 2: Maintain the pressure inside the specific heat ratio measuring component 2 at the equilibrium pressure P in step 1, and connect the second measuring chamber 4 and the first measuring chamber 3 to the specific heat ratio measuring component 2 in sequence, so as to measure the total volume V of sample 1 according to the principle of measuring specific heat ratio by vibration method.

[0104] Specifically, step 2 includes the following sub-steps:

[0105] Step 21: Connect the second measuring chamber 4 to the specific heat ratio measuring component 2, continuously introduce the measuring medium into the specific heat ratio measuring component 2, and keep the pressure in the specific heat ratio measuring component 2 at the equilibrium pressure P. The oscillator 23 in the vertical tube 22 undergoes simple harmonic motion under the action of the measuring medium.

[0106] Step 22: Detect the simple harmonic motion of oscillator 23 in step 21, and obtain the initial vibration period T0 of oscillator 23;

[0107] Step 23: Disconnect the connection between the specific heat ratio measuring component 2 and the second measuring chamber 4, and connect the specific heat ratio measuring component 2 to the first measuring chamber 3. The oscillator 23 in the vertical tube 22 will undergo simple harmonic motion under the action of the measuring gas.

[0108] Step 24: Detect the simple harmonic vibration of oscillator 23 in step 23, and obtain the vibration period T1 of oscillator 23 after loading sample 1;

[0109] Step 25: Calculate the total volume V of sample 1 based on the initial vibration period T0 of oscillator 23 and the vibration period T1 after loading sample 1.

[0110] In step 25, the total volume V of sample 1 is calculated using the following formula:

[0111]

[0112] Where: r is the specific heat capacity ratio of the measured medium;

[0113] P is the equilibrium pressure;

[0114] d is the diameter of oscillator 23;

[0115] T0 is the initial oscillation period of oscillator 23;

[0116] T1 is the vibration period of oscillator 23 after loading sample 1;

[0117] m is the mass of oscillator 23.

[0118] In this invention, gas is used as the measuring medium, and the porosity of sample 1 is measured by a combination of gas method and vibration method. The skeleton volume and total volume of sample 1 can be tested in one sample loading, avoiding the risk of sample 1 particles falling off during sample 1 transfer, which helps to ensure testing efficiency and accuracy, and provides a high level of integration of porosity measuring device, which is convenient for maintenance and application.

[0119] During the measurement of the total volume of sample 1, the equilibrium pressure is used as a constraint condition to make the gas pressure of the simple harmonic oscillation of oscillator 23 equal to the equilibrium pressure, thus preventing the test gas from seeping into the pores of sample 1, thereby ensuring the stability of the simple harmonic oscillation period and ensuring the accuracy of the total volume calculation of sample 1.

[0120] Using gas as the measuring medium to determine the skeleton volume and total volume reduces the contamination of sample 1, which is beneficial for subsequent analysis and testing of rock samples. It overcomes the water and oil sensitivity problems of sample 1 when measuring the total volume using liquid as the measuring medium, expands the scope of application, and improves the service capability of rock sample porosity testing.

[0121] In this invention, there are few restrictions on sample morphology; plunger, block, and granular rock samples can all be tested, which can meet more testing and research needs.

[0122] Example 5

[0123] This embodiment describes in detail the specific process of measuring the porosity of rock samples using the aforementioned porosity measuring device.

[0124] ① After placing the processed rock sample into the cup of the first measuring chamber 3, cover it with the top cover;

[0125] ② Open the second gas source 7 and inject the measuring gas with a certain pressure into the standard gas chamber 8 through the third pressure regulating valve 12;

[0126] ③ After the pressure in the standard gas chamber 8 stabilizes, open the first valve 13 to allow the measuring medium to enter the sealed space formed by the cup and the top cover of the first measuring chamber 3;

[0127] ④ After the pressure of the gas to be measured tends to stabilize, record the equilibrium pressure P. Calculate the skeleton volume V0 of the rock sample using a computer.

[0128] ⑤ Close the first valve 13, open the first pressure regulating valve 10, and continuously fill the buffer chamber 6 with measuring gas through the first gas source 5;

[0129] ⑥ Keep the third valve 17 closed, so that a sealed space is formed between the cup body and the top cover of the second measuring chamber 4;

[0130] ⑦ Open the second valve 16 and use the second pressure regulating valve 11 to make the gas pressure in the specific heat ratio measuring component 2 reach the equilibrium pressure P. Under the action of the measuring gas, the oscillator 23 in the vertical tube 22 will perform simple harmonic oscillation in the vertical tube 22.

[0131] ⑧ The vibration frequency of oscillator 23 is recorded by a photoelectric counter, and the initial vibration period T0 is calculated by a computer;

[0132] ⑨ Close the second valve 16 and open the third valve 17. Under the action of the measuring medium, the oscillator 23 in the vertical tube 22 performs simple harmonic motion in the vertical tube 22. The vibration frequency of the oscillator 23 is recorded by the photoelectric counter, and the vibration period T1 after loading sample 1 is calculated by the computer.

[0133] ⑩ Calculate the total volume V of the rock sample using the following formula:

[0134]

[0135] Where: r is the specific heat capacity ratio of the measured gas;

[0136] P is the equilibrium pressure;

[0137] d is the diameter of oscillator 23;

[0138] T0 is the initial oscillation period of oscillator 23;

[0139] T1 is the vibration period of oscillator 23 after loading sample 1;

[0140] m is the mass of oscillator 23.

[0141] Finally, the porosity φ of the rock sample is calculated: φ=(V-V0) / V*100%.

[0142] Where: φ is porosity, %; V is the total volume of the rock sample; V0 is the skeleton volume of the rock sample.

[0143] Example 6

[0144] After the processed rock sample is placed in the cup of the first measuring chamber 3, its top cover is closed. The second gas source 7 is opened, and nitrogen gas is injected into the standard gas chamber 8 through the third pressure regulating valve 12. Once the pressure stabilizes at 150 PSI, the first valve 13 is opened, allowing the measuring medium to enter the sealed space formed by the cup and top cover of the first measuring chamber 3. After the pressure of the measuring gas stabilizes, the equilibrium pressure P is 125 PSI. The skeleton volume V0 of the rock sample is calculated by computer to be 11.047 cm³. 3 .

[0145] Close the first valve 13, open the first pressure regulating valve 10, and continuously fill the buffer chamber 6 with nitrogen through the first gas source 5; keep the third valve 17 closed, so that a sealed space is formed between the cup body and the top cover of the second measuring chamber 4; open the second valve 16, and use the second pressure regulating valve 11 to make the pressure of the measuring medium reach the equilibrium pressure P (125 PSI). The oscillator 23 (spherical object) in the vertical tube 22 undergoes simple harmonic vibration under the action of the measuring medium; when the photoelectric counter records 50 vibrations of the oscillator 23, the computer calculates the initial vibration period T0 as 0.3472 seconds based on the recorded vibration time.

[0146] When the second valve 16 is closed and the third valve 17 is opened, the oscillator 23 inside the vertical tube 22 undergoes simple harmonic motion under the action of the measuring medium. When the oscillator 23 vibrates 50 times, the computer calculates the vibration period T1 after loading sample 1 as 0.3436 seconds by combining the recorded vibration time with the data from the photoelectric counter.

[0147] Using the formula V = rPd 4 (T0 2 -T1 2 The total volume V of the rock sample calculated using 64m is 12.755 cm³. 3 .

[0148] Where: r is the specific heat ratio of the gas being measured; P is the equilibrium pressure; d is the diameter of oscillator 23; T0 is the initial vibration period of oscillator 23; T1 is the vibration period of oscillator 23 after loading sample 1; and m is the mass of oscillator 23.

[0149] Finally, the porosity φ of the rock sample was calculated to be 13.4% using the formula φ=(V-V0) / V*100%.

[0150] In existing technical solutions, the combination of gas method and buoyancy method is a commonly used approach for determining rock sample porosity. The process involves the following steps: after pretreatment of the rock sample, the rock sample skeleton volume is first measured using a rock sample skeleton volume measuring device (e.g., a helium porosimeter), with helium or nitrogen as the measuring medium; secondly, based on the buoyancy method, the total volume of the rock sample is measured using a liquid-based total volume measuring device; finally, the porosity is calculated according to the porosity definition formula.

[0151] The choice of measuring medium for total volume determination of rock samples varies depending on the lithology of the rock sample. Anhydrous ethanol, kerosene, water, and magnetorheological fluids can all be used. Since rock samples are porous, the measuring medium inevitably enters the sample to varying degrees, causing contamination. Contaminated rock samples are detrimental to subsequent analysis and testing. Total volume determination devices generally fall into two categories. The first uses a rock sample total volume determination system. Before total volume determination, the rock sample does not need to be soaked or saturated with the measuring medium; the total volume is determined using a variable density method. The advantages are: firstly, the measuring medium can be selected as needed; secondly, there are fewer restrictions on the shape of the rock sample, allowing for testing of plunger-shaped, blocky, and granular rock samples; and thirdly, the testing process is automated, minimizing the impact of human factors. However, during the transfer of the rock sample from the skeleton volume measurement chamber to the total volume measurement cup, there is a risk that rock particles may fall, leading to errors in the test data and results. The second type is a simple device that combines a balance, a liquid tank, and a hanging rail. This is a traditional device. Before determining the total volume of the rock sample, it is usually necessary to immerse the rock sample in the measuring medium to obtain stable data when weighing it in the liquid. At the same time, before obtaining the weight data of the rock sample in the air, the measuring medium on the surface of the rock sample must be manually wiped off. In this process, it is more or less affected by human factors. Furthermore, when using this simple device to determine the total volume of the rock sample, it is difficult to determine the total volume of granular rock samples because the measuring medium on the surface of the granular rock sample is not easy to wipe off.

[0152] As can be seen from the above embodiments, when using the apparatus and method of the present invention to determine the porosity of rock samples, compared with the prior art, the present invention can determine the rock sample skeleton volume and total volume using a single gaseous measuring medium with a single sample loading, and then calculate the porosity according to the definition of porosity, demonstrating the characteristics and advantages of the technical solution of the present invention. Specifically, as follows:

[0153] First, the test can be completed in one sample loading. When testing the porosity of granular rock samples, the step of transferring the rock sample from the skeleton volume measurement chamber to the total volume measurement cup is reduced, avoiding the risk of sample particles falling off during the rock sample transfer process, which helps to ensure test efficiency and accuracy.

[0154] Second, using a gas as the measuring medium to determine the skeleton volume and total volume of a rock sample greatly reduces the problem of rock sample contamination during the testing process, which is beneficial for subsequent analysis and testing of the rock sample. It overcomes the problems of water and oil sensitivity of rock samples when measuring total volume using liquid as the measuring medium, expands the scope of application, and improves the service capability of rock sample porosity testing.

[0155] Third, it has low requirements on the morphology of rock samples, and can test plunger, blocky and granular rock samples, which can meet more testing and research needs.

[0156] Fourth, it has automated the entire process of testing rock sample skeleton volume, total volume, and calculating porosity, avoiding the influence of human factors during the testing process and helping to ensure testing efficiency and accuracy.

[0157] Fifth, compared with existing technologies, the integration of rock sample skeleton volume testing, total volume testing and porosity calculation realizes the integration of rock sample skeleton volume measuring device and total volume measuring device, which helps to reduce equipment management, maintenance and use costs.

[0158] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0159] The terms "upper" and "lower" used in this invention are defined in their usual sense. For example, referring to the direction of gravity, the direction of gravity is downward, and the opposite direction is upward. Similarly, "upper" refers to the top end, and "lower" refers to the bottom. These terms are used only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to these relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0160] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A porosity measuring device, characterized in that, include: A skeleton volume testing unit for measuring the skeleton volume of a sample by a gas method, the skeleton volume testing unit including a first measuring chamber for containing the sample; as well as The total volume testing unit is used to measure the total volume of the sample according to the principle of measuring specific heat ratio by vibration method. The total volume testing unit includes a selectively connected specific heat ratio measuring component and a second measuring chamber, wherein the volume of the internal space of the second measuring chamber is the same as the volume of the internal space of the first measuring chamber, and the first measuring chamber is selectively connected to the specific heat ratio measuring component. The total volume testing unit is configured to measure the total volume of the sample under the same pressure conditions as when the skeleton volume testing unit measures the skeleton volume; The specific heat ratio measuring assembly includes a gas storage chamber, a vertical tube, an oscillator, and an elastic element. The vertical tube is located at the top of the gas storage chamber and is connected to the interior of the gas storage chamber. The elastic element and the oscillator are arranged sequentially from top to bottom inside the vertical tube. By introducing measuring gas into the gas storage chamber, the oscillator can undergo simple harmonic vibration under the action of its own weight, the elastic force of the elastic element, and the pressure of the measuring gas.

2. The porosity measuring device according to claim 1, characterized in that, The specific heat ratio measuring component also includes a vibration detection element and a first pressure detection element. The vibration detection element is used to measure the simple harmonic motion of the oscillator; The first pressure sensing element is used to measure the pressure inside the gas storage chamber.

3. The porosity measuring device according to claim 1 or 2, characterized in that, The total volume testing unit also includes a first gas source. The outlet of the first gas source is connected to the specific heat ratio measuring component to provide measuring gas to the specific heat ratio measuring component.

4. The porosity measuring device according to claim 3, characterized in that, A buffer chamber is also provided between the first gas source and the specific heat ratio measuring component. A first pressure regulating valve is provided between the first gas source and the buffer chamber, and a second pressure regulating valve is provided between the buffer chamber and the specific heat capacity ratio measuring component.

5. The porosity measuring device according to claim 1 or 2, characterized in that, The skeleton volume testing unit includes a second gas source and a standard gas chamber. The second gas source is connected in sequence to the standard gas chamber and the first measuring chamber. A third pressure regulating valve is provided between the second gas source and the standard gas chamber, and a first valve is provided between the standard gas chamber and the first measuring chamber.

6. The porosity measuring device according to claim 5, characterized in that, The skeleton volume testing unit also includes a second pressure detection element and a third pressure detection element. The second pressure sensing element is connected to the pipeline between the standard gas chamber and the first valve, and the third pressure sensing element is connected to the pipeline between the first valve and the first measuring chamber.

7. A method for determining porosity, comprising using the porosity measuring device according to any one of claims 1-6 to determine the porosity of a rock sample, characterized in that, Includes the following steps: Step 1: After placing the sample into the first measuring chamber, introduce measuring gas at a preset pressure into the first measuring chamber to allow the measuring gas to diffuse into the pores of the sample. After the pressure stabilizes, record the equilibrium pressure. The skeletal volume of the sample is calculated based on the pressure change of the measured gas. ; Step 2: Maintain the pressure within the specific heat capacity ratio measuring component at the equilibrium pressure established in Step 1. The second and first measuring chambers are connected sequentially to the specific heat ratio measuring component to measure the total volume of the sample based on the principle of vibration method for measuring specific heat ratio. .

8. The porosity determination method according to claim 7, characterized in that, Step 2 includes the following sub-steps: Step 21: Connect the second measuring chamber to the specific heat ratio measuring component, continuously introduce measuring gas into the specific heat ratio measuring component, and maintain the pressure inside the specific heat ratio measuring component at the equilibrium pressure. The oscillator inside the vertical tube undergoes simple harmonic motion under the influence of the measuring gas; Step 22: Detect the simple harmonic motion of the oscillator from Step 21 and obtain the initial period of oscillation of the oscillator. ; Step 23: Disconnect the connection between the specific heat ratio measuring component and the second measuring chamber, and connect the specific heat ratio measuring component to the first measuring chamber. The oscillator in the vertical tube will undergo simple harmonic motion under the action of the measuring gas. Step 24: Detect the simple harmonic vibration of the oscillator in Step 23, and obtain the vibration period of the oscillator after loading the sample. ; Step 25: Based on the initial oscillation period of the oscillator Vibration period after sample loading Calculate the total volume of the sample .

9. The porosity determination method according to claim 8, characterized in that, In step 25, the total volume of the sample It is calculated using the following formula: ； in: To measure the specific heat ratio of a gas; To balance the pressure; The diameter of the oscillator; The initial oscillation period of the oscillator; The period of vibration of the oscillator after loading the sample; Let be the mass of the oscillator.

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