A method and system for determining volume parameters for volumetric high-pressure adsorption experiments

Abstract

The present invention provides a method and system for determining volume parameters for volumetric high-pressure adsorption experiments. The method first conducts pre-test verification on the relevant structures of the experimental system, then comprehensively considers the experimental requirements to analyze the pressure to be measured, and establishes a list of data to be measured by comprehensively referring to the volume calibration data of the reference cylinder and the sample cylinder; after disassembling the components, draining the water and drying them, the experimental system is reassembled, a series of test pressures are selected according to the experimental requirements, and in combination with the volume data of the reference cylinder and the sample cylinder in the list of data to be measured, the free space volume under different pressure conditions is measured for the experimental sample. By adopting the above solution, while comprehensively ensuring the reliability of the experimental components, it avoids the limitation that the existing experimental parameter calibration methods cannot be applied to high-burial-depth oil and gas reservoirs. It is not only applicable to various pressure conditions, but also can flexibly reflect the influence of gas molecules entering micro-nano pores under different pressures, significantly improving the reliability of volume parameter calibration and providing accurate data basis for volumetric adsorption and desorption experiments.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas reservoir geology and development, and particularly to a method and system for determining volume parameters for high-pressure adsorption experiments by the volumetric method. Background Art

[0002] In the field of oil and gas reservoir geology and development, gas content is an important parameter for obtaining the reserves of coalbed methane / shale gas reservoirs. Commonly used gas content measurement methods include the pressure-maintaining coring method, the in-situ gas content measurement method, and the laboratory measurement method. Among them, the laboratory measurement method measures the adsorbed gas volume and the free gas volume respectively. Specifically, the adsorbed gas volume is measured by adsorption experiments, and the free gas volume is calculated based on parameters such as porosity and gas saturation obtained from core experiments. The sum of the two is used as the gas content data. Therefore, accurately testing the adsorption and desorption experimental curve of the sample is very important for evaluating the gas content and the desorbed gas production characteristics.

[0003] In existing applications, the adsorption and desorption experimental curve data of the sample are obtained through volumetric adsorption and desorption experiments. For volumetric adsorption and desorption experiments, the size of the free space needs to be measured before the experiment. The free space is a key parameter for calculating the adsorption amount and is directly related to the accuracy of the adsorption amount. The existing GB / T 35210.1-2017 "Determination method for isothermal adsorption of shale methane - Part 1: Volumetric method" provides a means of measuring the free space by the helium injection method, which sets the initial pressure of the reference cylinder to 1 / 2 of the highest test pressure. After pressure equilibrium, the size of the free space is calculated according to Boyle's law. However, this method is more applicable to conventional constant-pressure gas reservoirs such as coalbed methane and normal-pressure shale. When the above experimental operations are applied to deep coal seams or shale gas reservoirs, they will be interfered by high-pressure factors and accurate and reliable test results cannot be obtained. Therefore, a new test method for the free space volume needs to be established to lay a foundation for accurately testing the high-pressure adsorption and desorption curve. Summary of the Invention

[0004] To solve the above problems, the present invention provides a method for determining volume parameters for high-pressure adsorption experiments by the volumetric method. The free space volume test logic established in the method can reflect the influence of high pressure on the vessel wall and gas movement, and the test results are more accurate, especially suitable for determining the free space volume of samples in the volumetric adsorption and desorption experiments of deep shale gas in China. In one embodiment, the method includes:

[0005] Pre-test configuration and processing steps: Conduct pre-test verification on the relevant structures of the experimental system, and establish a list of data to be measured based on the analysis results of the pressure to be measured for the overall experimental requirements, comprehensively referring to the volume calibration data of the reference cylinder and the sample cylinder;

[0006] Drying and reconstruction steps: After disassembling the experimental system for drainage, dry each component and reconnect them to form the experimental system;

[0007] Target volume measurement step: Select corresponding different test pressures from the list of data to be measured according to experimental requirements, introduce the corresponding reference cylinder volume and sample cylinder volume. After adding the sample, control the precision metering pump and related valves to inject helium into the reference cylinder, measure the experimental volume data of the reference cylinder and the sample cylinder respectively according to each test pressure, and calculate the free space volume corresponding to each test pressure.

[0008] Preferably, in one embodiment, in the pre-measurement configuration and processing step, it includes:

[0009] Pre-measurement verification step: Zero the high-precision metering pump for the experimental system control, then open the gas source valve (2), the first connection valve (4) and the second connection valve (5), close the first control valve (1) and the second control valve (3), inject the preset gas to test the pressure of the experimental system until it is verified that the airtightness of the system meets the experimental requirements, and evacuate the experimental system.

[0010] Furthermore, in one embodiment, in the pre-measurement configuration and processing step, it further includes:

[0011] Analysis step of the pressure to be measured: Statistically analyze the current formation information of the oil and gas reservoir under current development and design, and set relevant extended formation information of the oil and gas reservoir based on the statistical results. Analyze the formation pressure data of the current formation information of the oil and gas reservoir and the extended formation information of the oil and gas reservoir as the pressure data to be measured reflecting comprehensive experimental requirements.

[0012] In one embodiment, in the pre-measurement configuration and processing step, it further includes:

[0013] Reference cylinder volume calibration step: Control the precision metering pump and related valves to measure the volume data of each type of reference cylinder under steady pressure according to the pressure data to be measured;

[0014] Sample cylinder volume calibration step: Adjust the experimental system so that the gas source is directly connected to the sample cylinder, and control the precision metering pump and related valves to measure the volume data of each type of sample cylinder under steady pressure according to the pressure data to be measured.

[0015] Specifically, in one embodiment, in the pre-measurement configuration and processing step, it further includes:

[0016] After obtaining the reference cylinder volume and the sample cylinder volume under different pressures to be measured respectively, use the linear interpolation method to determine the reference cylinder and sample cylinder volumes under any pressure to be measured within the range of the list of data to be measured, and associate and store them in the list of data to be measured.

[0017] Specifically, in the reference cylinder volume calibration step, it includes the following operations:

[0018] A1. After evacuating the air, close the first control valve (1) and the second connection valve (5), and turn on the temperature control device to set the temperature to the preset experimental temperature;

[0019] A2. Use a precision metering pump to inject the set fluid into the reference cylinder until the pressure reaches the first pressure to be measured P 11 after stabilization, and record the volume V of the liquid pumped out by the pump when the pressure is stable 11 ;

[0020] A3. Further set the pump pressure to the second pressure to be measured P 12 , and the pump continues to pump out the liquid until the pressure reaches P 12 . After the pressure stabilizes, record the volume V 12 ;

[0021] Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and obtain a series of P 1n , V 1n as the reference cylinder volume calibration data corresponding to different test pressures, open the first control valve (1), and relieve the pressure of the experimental system.

[0022] In the step of calibrating the volume of the sample cylinder, the following operations are included:

[0023] B1. Temporarily disassemble the reference cylinder, connect the sample cylinder through valve 5, zero the high-precision metering pump and then connect it to valve 5;

[0024] B2. After evacuating the air, close the first control valve (1) and the second connection valve (5), and turn on the temperature control device to set the temperature to the preset experimental temperature;

[0025] B3. Use a precision metering pump to inject the set fluid into the sample cylinder until the pressure reaches the first pressure to be measured P 21 after stabilization, and record the volume V of the liquid pumped out by the pump when the pressure is stable 21 ;

[0026] B4. Further set the pump pressure to the second pressure to be measured P 22 , and the pump continues to pump out the liquid until the pressure reaches P 22 . After the pressure stabilizes, record the volume V 22 ;

[0027] Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and obtain a series of P 2n , V 2n as the sample cylinder volume calibration data corresponding to different test pressures, open the first control valve (1), and relieve the pressure of the experimental system.

[0028] In one embodiment, in the step of measuring the target volume, the following operations are included:

[0029] C1. After pressure testing the experimental system, place the sample in the sample cylinder, then evacuate the air and set the required experimental temperature.

[0030] C2. Close the second connection valve (5), open the first connection valve (4), and inject helium into the reference cylinder so that the initial pressure and temperature values of the balanced reference cylinder and sample cylinder meet the experimental requirements.

[0031] C3. Close the first connection valve (4), open the second connection valve (5), and record the balanced pressure and temperature of the reference cylinder and sample cylinder after pressure balance.

[0032] C4. When the balanced pressure reaches the first test pressure, retrieve the reference cylinder and sample cylinder volume calibration data corresponding to this test pressure in the list of data to be measured, and use the linear interpolation calculation method to determine the corresponding test reference cylinder volume and test sample cylinder volume.

[0033] C5. Then calculate the free space volume at the first test pressure according to Boyle's law.

[0034] Repeat the above operations until the free space volumes corresponding to all test pressures are obtained.

[0035] Based on the method steps described in any one or more of the above embodiments, the present invention further provides a storage medium, on which program codes for implementing the methods described in any one or more of the above embodiments are stored.

[0036] Based on other aspects of the method described in any one or more of the above embodiments, the present invention further provides a volume parameter determination system for volumetric high-pressure adsorption experiments, and this system executes the methods described in any one or more of the above embodiments.

[0037] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0038] The present invention provides a method and system for determining volume parameters for volumetric high-pressure adsorption experiments. This method first conducts pre-test verification on the relevant structures of the experimental system, conducts multi-level verification from aspects such as zero calibration of the metering pump and overall airtightness of the experimental system, controls the experimental influencing factors at the experimental pressure and experimental temperature from the source, and avoids interference from other factors on the experimental data. Further, this application comprehensively considers the experimental requirements to analyze the pressure to be measured, establishes a list of data to be measured by comprehensively referring to the volume calibration data of the reference cylinder and the sample cylinder, provides data retrieval support for the formal determination of the free space volume, and directly retrieves the volume data of the reference cylinder and the sample cylinder to participate in the operation during the experiment, which considerably improves the timeliness of the experiment.

[0039] In addition, during the process of measuring the free space volume, the solution of the present invention not only breaks through the limitation that the existing experimental parameter calibration means cannot be applied to high-buried-depth oil and gas reservoirs, but also can flexibly reflect the influence of gas molecules entering micro-nano pores under different pressures, significantly improving the reliability of volume parameter calibration. When applied to adsorption and desorption experiments, accurate adsorption and desorption curves can be obtained, which is helpful for the development and optimization of oil and gas development projects.

[0040] Other features and advantages of the present invention will be described in the following specification, and some of them will become obvious from the specification or can be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Brief Description of the Drawings

[0041] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0042] Figure 1 is a schematic flowchart of a method for determining volume parameters for a volumetric high-pressure adsorption experiment in an embodiment of the present invention;

[0043] Figure 2 is a schematic diagram of the components and connections of an experimental system for applying a method for determining volume parameters for a volumetric high-pressure adsorption experiment in another embodiment of the present invention

[0044] Figure 3 is a schematic structural diagram of a system for determining volume parameters for a volumetric high-pressure adsorption experiment provided by an embodiment of the present invention. Detailed Embodiments

[0045] The following will describe in detail the embodiments of the present invention in conjunction with the drawings and embodiments. Through this, those skilled in the art of the present invention can fully understand how to apply technical means to solve technical problems and achieve the process of technical effects, and implement the present invention according to the above implementation process. It should be noted that as long as there is no conflict, the various embodiments in the present invention and the various features of each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0046] Although the flowchart describes the operations as sequential processes, many of the operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. When the operations are completed, the process can be terminated, but there can also be additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0047] Computer devices include user devices and network devices. Among them, user devices or clients include, but are not limited to, computers, smartphones, PDAs, etc.; network devices include, but are not limited to, a single network server, a server group composed of multiple network servers, or a cloud composed of a large number of computers or network servers based on cloud computing. The computer device can operate alone to implement the present invention, or can be connected to a network and implement the present invention through interactive operations with other computer devices in the network. The network where the computer device is located includes, but is not limited to, the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0048] Here, terms such as "first", "second", etc. may be used to describe various units, but these units should not be limited by these terms. These terms are only used to distinguish one unit from another. The term "and / or" used here includes any and all combinations of one or more of the listed related items. When a unit is referred to as being "connected" or "coupled" to another unit, it can be directly connected or coupled to the other unit, or there may be intermediate units.

[0049] The terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a", "an" used here are also intended to include the plural. It should also be understood that the terms "comprises" and / or "comprising" used here specify the presence of the stated features, integers, steps, operations, units and / or components, and do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components and / or their combinations.

[0050] Gas content is an important parameter for obtaining the reserves of coalbed methane / shale gas reservoirs. Currently, the commonly used gas content measurement methods include the pressure-maintaining coring method, the in-situ gas content measurement method, and the laboratory measurement method. Among them, the pressure-maintaining coring method has a high cost, and once leakage occurs during the drillstem testing process, it will cause result errors; the in-situ gas content measurement method is widely used, and the test results consist of three parts: desorbed gas volume, lost gas volume, and residual gas volume, and the accurate estimation of the lost gas volume has not been completely solved; the laboratory measurement method measures the adsorbed gas volume and the free gas volume separately, measures the adsorbed gas volume by adsorption experiments, and calculates the free gas volume according to parameters such as porosity and gas saturation obtained from core experiments. The sum of the two is the gas content. Accurately testing the adsorption and desorption experimental curve of the sample is very important for evaluating the gas content and the desorbed gas production characteristics.

[0051] For the volumetric adsorption and desorption experiment, the free space size needs to be measured before the experiment. The free space is a key parameter for calculating the adsorption amount and is directly related to the accuracy of the adsorption amount. GB / T 35210.1-2017 "Determination method for isothermal adsorption of shale methane - Part 1: Volumetric method" uses the helium injection method. The initial pressure of the reference cylinder is set to 1 / 2 of the highest test pressure. After pressure equilibrium, the free space size is calculated according to Boyle's law. This method is more applicable to coalbed methane and conventional shale gas reservoirs. However, for the deep shale gas reservoirs in China, the burial depth of shale gas in the Weiyuan and Yongchuan blocks has exceeded 3500 m and the pressure has reached over 70 MPa. At higher pressures, the walls of the equipment will undergo a certain degree of deformation, which will affect the measurement of the free space volume. In addition, as the pressure increases, gas enters smaller pores, which will also cause changes in the free space volume. Therefore, when conducting the volumetric high-pressure shale adsorption and desorption experiment, a new test method for the free space volume needs to be established to lay the foundation for accurately testing the high-pressure adsorption and desorption curves.

[0052] In summary, under high-pressure conditions, the walls of the reference cylinder and the sample cylinder in the volumetric adsorption experiment process will deform under high pressure, and gas can enter more micro-nano pore spaces under high pressure. The existing test methods do not consider the above problems, resulting in a certain degree of error in the adsorption and desorption curves and affecting the accurate evaluation of the adsorbed / desorbed gas volume.

[0053] To solve the above problems, the present invention provides a method and system for determining volume parameters for a volumetric high-pressure adsorption experiment, which considers the characteristics of wall deformation under high pressure and gas molecules entering more micro-nano pores during the process of determining relevant volume parameters, and can more accurately measure the volume parameters of samples under different high-pressure conditions, thus laying the foundation for accurately measuring the adsorption and desorption curves under high pressure.

[0054] Next, the detailed process of the method of the embodiment of the present invention will be described in detail based on the accompanying drawings. The steps shown in the flowchart of the accompanying drawings can be executed in a computer system including, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0055] Example 1

[0056] Figure 1 The flowchart shows the process of the method for determining volume parameters for a volumetric high-pressure adsorption experiment provided in Embodiment 1 of the present invention. Referring to Figure 1 it can be seen that the method includes the following steps.

[0057] Pre-test configuration and processing step S110: Perform pre-test verification on the relevant structures of the experimental system, and establish a list of test data based on the pressure analysis results to be tested according to the comprehensive experimental requirements and the volume calibration data of the reference cylinder and the sample cylinder;

[0058] Drying and reconstruction step S120: After disassembling the experimental system to drain the water, each component is dried and reconnected to form the experimental system;

[0059] Target volume determination step S130: Select corresponding different test pressures from the list of test data according to experimental requirements, introduce the corresponding reference cylinder volume and sample cylinder volume, and after adding the sample, control the precision metering pump and related valves to inject helium into the reference cylinder, and measure the experimental volume data of the reference cylinder and the sample cylinder according to each test pressure, and calculate the free space volume corresponding to each test pressure.

[0060] Specifically, in practical applications, considering that the numerical value of the high-precision metering pump is used as the direct representation value of the measurement result during the experiment, its operation standardization directly affects the effectiveness of the measurement process and the reliability of the measurement result. Therefore, the operation standardization of the high-precision metering pump must be strictly guaranteed before and during the experiment. Therefore, in the pre-test configuration and processing steps, it includes:

[0061] Verification steps before testing: control the high-precision metering pump of the experimental system to zero, then open the gas source valve 2, the first connecting valve 4 and the second connecting valve 5, close the first control valve 1 and the second control valve 3, inject the preset gas to test the pressure of the experimental system, until it is verified that the air tightness of the system meets the experimental requirements, and evacuate the experimental system.

[0062] By adopting the verification strategy in the above embodiment, the high-precision metering pump can be reset and adjusted at the same time, and abnormal status information of the metering pump and other airtight components can be discovered in time before measurement, thereby avoiding invalid experimental operations due to hardware failures during the experiment, saving resources and time consumption caused by rework and work delays to a certain extent, and improving the timeliness of experimental execution.

[0063] In actual application, based on the attached Figure 2 As shown in the figure, connect the experimental system well, open valve 2, valve 4, valve 5, close valve 1 and valve 3, test the pressure of the experimental process with the set gas, check the air tightness, and release the gas after ensuring the air tightness is good. Then connect the vacuum pump from valve 1, close valves 2 and 3, open valves 4 and 5, and vacuum the process.

[0064] Additionally, to enable the experimental results to be widely applied to various development scenarios within the field, the comprehensiveness of the pressures to be measured it covers is crucial. Based on this, the researchers of the present invention synchronously considered the current oil and gas reservoir formation conditions involved and the possible oil and gas reservoir formation conditions within a set future time period, constructed a list of pressures to be measured, and provided an indication for the formal experiment.

[0065] Therefore, in one embodiment, in the pre-test configuration and processing steps, it further includes:

[0066] Step of analyzing the pressures to be measured: Statistically analyze the current oil and gas reservoir formation information of the currently developed and designed oil and gas reservoir, set relevant extended oil and gas reservoir formation information based on the statistical results, and analyze the formation pressure data of the current oil and gas reservoir formation information and the extended oil and gas reservoir formation information as the pressures to be measured data reflecting the comprehensive experimental requirements.

[0067] Based on the comprehensively measured pressures to be measured data, calibrate in advance the respective reference cylinder volumes and sample cylinder volumes corresponding to different pressure conditions. During the execution of the experiment, it can be directly retrieved using the test pressure as a label, which can significantly reduce the redundant operations during the formal experiment process and ensure the experimental efficiency. Therefore, in one embodiment, in the pre-test configuration and processing steps, it further includes:

[0068] Step of calibrating the reference cylinder volume: Control the precision metering pump and related valves to respectively measure the volume data of each type of reference cylinder under a stable pressure according to the pressures to be measured data;

[0069] Step of calibrating the sample cylinder volume: Adjust the experimental system so that the gas source is directly connected to the sample cylinder, and control the precision metering pump and related valves to respectively measure the volume data of each type of sample cylinder under a stable pressure according to the pressures to be measured data.

[0070] Furthermore, in the pre-test configuration and processing steps, it further includes:

[0071] After obtaining the reference cylinder volume and sample cylinder volume under different pressures to be measured respectively, use the linear interpolation method to determine the reference cylinder and sample cylinder volumes under any pressure to be measured within the range of the measured data list, and associate and store them in the measured data list.

[0072] In actual application, the calibration of the volume parameters in the volumetric adsorption experiment includes the calibration of the reference cylinder and sample cylinder volumes and the calibration of the free space volume. The calibration of the free space volume uses the volumes of the reference cylinder and sample cylinder. In this application, when calibrating the volumes of the reference cylinder and sample cylinder, a high-precision metering pump is used for metering respectively to obtain the cylinder volumes under different pressures. The cylinder volume at any pressure within the test range can be obtained by the linear interpolation method. Then, the free space volume of the sample cylinder under different pressures is calibrated with helium. The volumes of the reference cylinder and sample cylinder used are linearly interpolated by the foregoing method and are associated with the corresponding pressure data to be measured and stored in the list of data to be measured, which can effectively ensure the accurate calibration results of the reference cylinder and sample cylinder under different pressure conditions. Herein, the volumes of the reference cylinder and sample cylinder include the volumes of the cylinder body and the connected pipelines and valves.

[0073] Specifically, in one embodiment, in the step of calibrating the reference cylinder volume, the following operations are included:

[0074] A1. After evacuating, close the first control valve 1 and the second connection valve 5, and turn on the constant temperature device to set the temperature to the preset experimental temperature;

[0075] A2. Use a precision metering pump to inject a set fluid into the reference cylinder until the pressure reaches the first pressure to be measured P 11 after stabilization, and record the volume V 11 of the liquid pumped out by the pump when the pressure is stable; wherein, the set fluid can be deionized water;

[0076] A3. Further set the pump pressure to the second pressure to be measured P 12 , and the pump continues to pump out the liquid until the pressure reaches P 12 , and record the volume V 12 after the pressure is stable;

[0077] Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and obtain a series of P 1n and V 1n as the reference cylinder volume calibration data corresponding to different test pressures, open the first control valve 1, and the experimental system is depressurized.

[0078] In actual application, after the evacuation is completed, close valves 1 and 5, and turn on the constant temperature device to set the temperature to the experimental temperature. Use a precision metering pump to inject a fluid (usually deionized water) into the upstream reference cylinder until the pressure reaches P 11 , and record the volume V 11 of the liquid pumped out by the pump after the pressure is stable; then set the pump pressure to P 12 , and the pump continues to pump out the liquid until the pressure reaches P 12 , and record the volume V 12 after the pressure is stable; repeat the above process until the pressure reaches the highest set pressure of the experiment. Obtain a series of P 1n, V 1n Open valve 1 to relieve the pressure of the experimental system process.

[0079] In one embodiment, in the step of calibrating the volume of the sample cylinder, the following operations are included:

[0080] B1. Temporarily disassemble the reference cylinder, connect the sample cylinder through valve 5, zero the high-precision metering pump and then connect it to valve 5;

[0081] B2. After evacuating, close the first control valve 1 and the second connection valve 5, and turn on the temperature control device to set the temperature to the preset experimental temperature;

[0082] B3. Inject the set fluid into the sample cylinder with a precision metering pump until the pressure reaches the first pressure to be measured P 21 , and record the volume V of the liquid pumped out by the pump when the pressure is stable 21 ; wherein, the set fluid can be deionized water;

[0083] B4. Further set the pump pressure to the second pressure to be measured P 22 , and the pump continues to pump out the liquid until the pressure reaches P 22 , and record the volume V after the pressure is stable 22 ;

[0084] Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and obtain a series of P 2n , V 2n as the calibration data of the sample cylinder volume corresponding to different test pressures, open the first control valve 1, and relieve the pressure of the experimental system.

[0085] In actual operation, disconnect the reference cylinder from valve 5, zero the metering pump and then connect it to valve 5, and obtain a series of P 2n , V 2n according to steps B2 and B3, and obtain the volume V of the reference cylinder at different pressures P 1n , and the volume V of the sample cylinder at different pressures P 1n . Using the linear interpolation method, the volume V of the reference cylinder and the volume V of the sample cylinder at any pressure within the test range can be obtained 2n . 2n . r and the volume V of the sample cylinder s .

[0086] Furthermore, after clarifying each item to be measured in the list of data to be measured through the above operations, further carry out the measurement of the free space volume from low pressure to high pressure for the experimental sample according to the experimental requirements. It should be noted that before officially carrying out the free space volume experiment for the sample, it is necessary to perform the drying and reconstruction operation on each component of the experimental system. Specifically, in one embodiment, in the step of drying and reconstruction, the following operations are specifically performed:

[0087] Disassemble the experimental system process, drain the water from each component, place each component in an oven for drying, and reconnect them to form the experimental system after drying. It should be noted that when reconstructing the system here, the reference cylinder removed previously needs to be reconnected between the first connection valve 4 and the second connection valve 5 to realize the functional connection of the reference cylinder with the gas source and the metering pump.

[0088] To ensure the accuracy of subsequent formal tests, in one embodiment, after drying and reconstructing each component of the experimental system, the pre-test verification steps are carried out again to ensure the airtightness and effectiveness of each component of the experimental system. Specifically, the high-precision metering pump of the experimental system can be cleared, and then the gas source valve 2, the first connection valve 4, and the second connection valve 5 are opened, the first control valve 1 and the second control valve 3 are closed, and a preset gas is injected to pressure test the experimental system until it is verified that the airtightness of the system meets the experimental requirements, and then the experimental system is evacuated.

[0089] Further, in one embodiment, in the target volume measurement step, the free space volume measurement of the sample is carried out according to the following operations:

[0090] C1. After pressure testing the experimental system, place the sample in the sample cylinder, and then evacuate and set the required experimental temperature;

[0091] C2. Close the second connection valve 5, open the first connection valve 4, and inject helium into the reference cylinder to make the initial pressure and temperature values of the balanced reference cylinder and the sample cylinder meet the experimental requirements;

[0092] C3. Close the first connection valve 4, open the second connection valve 5, and record the balanced pressure and temperature of the reference cylinder and the sample cylinder after pressure balance;

[0093] C4. When the balanced pressure reaches the first test pressure, retrieve the volume calibration data of the reference cylinder and the sample cylinder corresponding to this test pressure in the list of data to be measured, and use the linear interpolation calculation method to determine the corresponding test reference cylinder volume and test sample cylinder volume;

[0094] C5. Then calculate the free space volume at the first test pressure according to Boyle's law;

[0095] Repeat the above operations until the free space volumes corresponding to all test pressures are obtained.

[0096] In actual application, the free space volume at the first pressure is calibrated with helium. Specifically, the experimental process is successively pressure tested, the sample is placed in the sample cylinder, evacuated, and the experimental temperature is set. Then valve 5 is closed, valve 4 is opened, helium is injected into the reference cylinder, and the pressure value P of the reference cylinder is recorded after balance r1 and the gas compressibility factor Z r1, the pressure value P of the sample cylinder s1 and the gas compressibility factor Z s1 , the system temperature value T1. Close valve 4 and open valve 5. After pressure equilibrium, record the reference cylinder pressure value P r2 and the gas compressibility factor Z r2 , the pressure value P of the sample cylinder s2 and the gas compressibility factor Z s2 , the system temperature value T2. Calculate the free space volume at this pressure according to the principle of material balance. The calculation of the gas compressibility factor is carried out in accordance with GB / T17747.2-2011. The volume V r of the reference cylinder is obtained by linear interpolation from the pre-measurement configuration and processing steps, and thus the free space volume V f at the first pressure is obtained. Specifically, the free volume space volume calculation formula is:

[0097]

[0098] In the formula:

[0099] V f represents the free space volume, with the unit of cubic centimeter (cm 3 );

[0100] V r represents the volume of the reference cylinder, with the unit of cubic centimeter (cm 3 );

[0101] P r1 represents the reference cylinder pressure at the first equilibrium, with the unit of megapascal (MPa);

[0102] P s1 represents the sample cylinder pressure at the first equilibrium, with the unit of megapascal (MPa);

[0103] P r2 represents the reference cylinder pressure at the second equilibrium, with the unit of megapascal (MPa);

[0104] P s2 represents the sample cylinder pressure at the second equilibrium, with the unit of megapascal (MPa);

[0105] T1 represents the system temperature at the first equilibrium, with the unit of Kelvin (K);

[0106] T2 represents the system temperature at the second equilibrium, with the unit of Kelvin (K);

[0107] Z r1 represents the compressibility factor of the gas in the reference cylinder at the first equilibrium, dimensionless;

[0108] Z s1 represents the compressibility factor of the gas in the sample cylinder at the first equilibrium, dimensionless;

[0109] Z r2 represents the compressibility factor of the gas in the second equilibrium reference cylinder, dimensionless;

[0110] Z s2 represents the compressibility factor of the gas in the second equilibrium sample cylinder, dimensionless.

[0111] For the free space volume at different pressures, following the same operation process as above, according to the set test pressure sequence, the pressure of the reference cylinder was gradually increased using helium gas, and a series of free space volumes from low to high pressure were obtained. The free space volume calibrated by the above means of the present application takes into account both the deformation of the cylinder body with the increase of pressure and the characteristic that helium gas enters more rock spaces under high pressure, and the result is more accurate.

[0112] The method for calibrating volume parameters in the volumetric high-pressure adsorption experiment provided by the present invention can effectively overcome the technical drawback that the existing method for calibrating volume parameters cannot take into account the deformation of the vessel wall under high pressure and the characteristic that gas molecules enter more micro-nano pores, and the test result cannot reflect the high-pressure characteristics. The present invention comprehensively considers the deformation of the equipment vessel wall and the high-pressure characteristics, establishes a test method for the deformation amount of the vessel wall at different pressures, and on the basis of considering the deformation amount of the vessel wall, measures the free space volume of the sample from low pressure to high pressure. The established method for calibrating volume parameters can reflect the influence of high pressure on the vessel wall and gas movement, and the test result is also more accurate, especially suitable for the determination of volume parameters in the volumetric adsorption and desorption experiment of deep shale gas in China.

[0113] For the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0114] It should be noted that in other embodiments of the present invention, the method can also obtain a new method for calibrating volume parameters in the adsorption experiment by combining one or more of the above embodiments.

[0115] Furthermore, based on the method in any one or more of the above embodiments of the present invention, the present invention also provides a storage medium, on which program codes for implementing the method described in any one or more of the above embodiments are stored. When the codes are executed by an operating system, the method for determining volume parameters for the volumetric high-pressure adsorption experiment as described above can be implemented.

[0116] Example 2

[0117] The method is described in detail in the embodiments disclosed in the present invention. The method of the present invention can be implemented by various forms of devices or systems. Therefore, based on other aspects of the method described in any one or more embodiments, the present invention also provides a volume parameter determination system for a volumetric high-pressure adsorption experiment, which is used to execute the volume parameter determination method for a volumetric high-pressure adsorption experiment described in any one or more embodiments. Specific embodiments are given below for detailed description.

[0118] Attached Figure 3 FIG. 4 is a schematic diagram showing a structure of a volume parameter determination system for a volumetric high-pressure adsorption experiment provided in an embodiment of the present invention. Figure 3 As shown, the system comprises:

[0119] Pre-test configuration and processing module, which is configured to perform pre-test verification on the relevant structures of the experimental system, and to establish a list of test data based on the pressure analysis results to be tested according to the comprehensive experimental requirements and the volume calibration data of the reference cylinder and the sample cylinder;

[0120] A drying and reconstruction module is configured to disassemble the experimental system for drainage, dry the components, and reconnect them to form the experimental system;

[0121] The target volume determination module is configured to select corresponding different test pressures from the list of test data according to experimental requirements, introduce the corresponding reference cylinder volume and sample cylinder volume, and after adding the sample, control the precision metering pump and related valves to inject helium into the reference cylinder, measure the experimental volume data of the reference cylinder and the sample cylinder according to each test pressure, and calculate the free space volume corresponding to each test pressure.

[0122] In one embodiment, the pre-test configuration and processing module includes:

[0123] The pre-test verification unit is used to control the high-precision metering pump to zero for the experimental system, and then open the gas source valve 2, the first connecting valve 4 and the second connecting valve 5, close the first control valve 1 and the second control valve 3, and inject the preset gas to test the pressure of the experimental system until it is verified that the air tightness of the system meets the experimental requirements, and then evacuate the experimental system.

[0124] Furthermore, in one embodiment, the pre-test configuration and processing module includes:

[0125] The pressure analysis unit to be tested is used to statistically analyze the current oil and gas reservoir formation information of the currently developed and designed oil and gas reservoir, and set the relevant extended oil and gas reservoir formation information based on the statistical results, and analyze the formation pressure data of the current oil and gas reservoir formation information and the extended oil and gas reservoir formation information as the pressure data to be tested that reflects the comprehensive experimental needs.

[0126] In a preferred embodiment, the pre-test configuration and processing module further includes:

[0127] A reference cylinder volume calibration unit, which is used to control the precision metering pump and related valves to measure the volume data of each type of reference cylinder under a steady pressure according to the pressure data to be measured;

[0128] A sample cylinder volume calibration unit, which is used to adjust the experimental system to directly connect the gas source to the sample cylinder, and control the precision metering pump and related valves to measure the volume data of each type of sample cylinder under a steady pressure according to the pressure data to be measured.

[0129] Specifically, the pre-test configuration and processing module is further configured to:

[0130] After obtaining the reference cylinder volume and the sample cylinder volume under different pressures to be measured respectively, use the linear interpolation method to determine the reference cylinder and sample cylinder volumes under any pressure to be measured within the range of the data list to be measured, and associate and store them in the data list to be measured.

[0131] In one embodiment, the reference cylinder volume calibration unit is used for the following operations:

[0132] A1. After evacuating the air, close the first control valve 1 and the second connection valve 5, and turn on the constant temperature device to set the temperature to the preset experimental temperature;

[0133] A2. Use the precision metering pump to inject the set fluid into the reference cylinder until the pressure reaches the first pressure to be measured P 11 , and record the volume V 11 of the liquid pumped out by the pump when the pressure is stable;

[0134] A3. Then set the pump pressure to the second pressure to be measured P 12 , and the pump continues to pump out the liquid until the pressure reaches P 12 , and record the volume V 12 after the pressure is stable;

[0135] Repeat the above operations until the pressure reaches the highest pressure to be measured in the data list to be measured, and obtain a series of P 1n , V 1n as the reference cylinder volume calibration data corresponding to different test pressures, open the first control valve 1, and the experimental system is depressurized.

[0136] Further, the sample cylinder volume calibration unit is used for the following operations:

[0137] B1. Temporarily disassemble the reference cylinder, connect the sample cylinder through the valve 5, zero the high-precision metering pump and then connect it to the valve 5;

[0138] B2. After evacuating the air, close the first control valve 1 and the second connection valve 5, and turn on the constant temperature device to set the temperature to the preset experimental temperature;

[0139] B3. Use a precision metering pump to inject the set fluid into the sample cylinder until the pressure reaches the first pressure to be measured P 21 after stabilization, and record the volume V of the liquid pumped out by the pump when the pressure is stable 21 ;

[0140] B4. Then set the pump pressure to the second pressure to be measured P 22 , and the pump continues to pump out the liquid until the pressure reaches P 22 , and record the volume V after the pressure is stable 22 ;

[0141] Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and obtain a series of P 2n , V 2n as the calibration data of the sample cylinder volume corresponding to different test pressures, open the first control valve 1, and relieve the pressure of the experimental system.

[0142] In one embodiment, the target volume determination module conducts the free space volume determination for the sample through the following operations:

[0143] C1. After pressure testing the experimental system, place the sample in the sample cylinder, and then evacuate the air and set the required experimental temperature;

[0144] C2. Close the second connection valve 5, open the first connection valve 4, and inject helium into the reference cylinder so that the initial pressure and temperature values of the balanced reference cylinder and sample cylinder meet the experimental requirements;

[0145] C3. Close the first connection valve 4, open the second connection valve 5, and record the balanced pressure and temperature of the reference cylinder and sample cylinder after the pressure is balanced;

[0146] C4. When the balanced pressure reaches the first test pressure, retrieve the calibration data of the reference cylinder and sample cylinder volumes corresponding to this test pressure in the list of data to be measured, and use the linear interpolation calculation method to determine the corresponding test reference cylinder volume and test sample cylinder volume;

[0147] C5. Then calculate the free space volume at the first test pressure according to Boyle's law;

[0148] Repeat the above operations until the free space volumes corresponding to all test pressures are obtained.

[0149] In the volume parameter determination system for volumetric high-pressure adsorption experiments provided by the embodiments of the present invention, each module or unit structure can operate independently or in combination according to actual experimental needs to achieve corresponding technical effects.

[0150] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and do not imply limitation.

[0151] The "one embodiment" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrase "one embodiment" that appears throughout the specification does not necessarily refer to the same embodiment.

[0152] Although the embodiments disclosed in the present invention are as above, the content described is only an embodiment adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains may make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for determining volume parameters for a volumetric high-pressure adsorption experiment, characterized in that, The method includes: Pre - measurement configuration and processing steps: Conduct pre - measurement verification on the relevant structures of the experimental system, and based on the analysis results of the pressure to be measured for comprehensive experimental requirements, establish a list of data to be measured by comprehensively referring to the volume calibration data of the reference cylinder and the sample cylinder; Drying and reconstruction steps: After disassembling the experimental system for drainage, dry each component and reconnect them to form the experimental system; Target volume measurement steps: According to experimental requirements, select corresponding different test pressures from the list of data to be measured, introduce the corresponding reference cylinder volume and sample cylinder volume, add the sample, then control the precision metering pump and relevant valves to inject helium into the reference cylinder, measure the experimental volume data of the reference cylinder and the sample cylinder respectively according to each test pressure, and calculate the free - space volume corresponding to each test pressure; In the pre - measurement configuration and processing steps, it includes: Reference cylinder volume calibration steps: Control the precision metering pump and relevant valves to measure the volume data of each type of reference cylinder under a stable pressure according to the pressure data to be measured; Sample cylinder volume calibration steps: Adjust the experimental system so that the gas source is directly connected to the sample cylinder, and control the precision metering pump and relevant valves to measure the volume data of each type of sample cylinder under a stable pressure according to the pressure data to be measured; In the reference cylinder volume calibration steps, the following operations are included: A1. After evacuating, close the first control valve (1) and the second connection valve (5), and turn on the temperature control device to set the temperature to the preset experimental temperature; A2. Use a precision metering pump to inject the set fluid into the reference cylinder until the pressure reaches the first pressure to be measured P after stabilization. 11 , record the volume V of liquid pumped out when the pressure is stable 11 ; A3. Further, set the pump pressure to the second pressure to be measured, P 12 , and the pump continues to pump out the liquid until the pressure reaches P 12 . After the pressure stabilizes, record the volume V 12 ; Repeat the above operation until the pressure reaches the highest pressure to be measured in the data list to be measured, and a series of P 1n , V 1n are used as the reference cylinder volume calibration data corresponding to different test pressures. Open the first control valve (1) to relieve the pressure of the experimental system.

2. The method according to claim 1, characterized in that, In the pre - measurement configuration and processing steps, it includes: Pre - measurement verification steps: Zero the high - precision metering pump for the experimental system, then open the gas source valve (2), the first connection valve (4) and the second connection valve (5), close the first control valve (1) and the second control valve (3), inject the preset gas to test - press the experimental system until it is verified that the airtightness of the system meets the experimental requirements, and evacuate the experimental system.

3. The method according to claim 1, characterized in that, In the pre - measurement configuration and processing steps, it also includes: Pressure to be measured analysis steps: Statistically analyze the current oil and gas reservoir formation information of the currently developed and designed oil and gas reservoir, and based on the statistical results, set relevant extended oil and gas reservoir formation information, and analyze the formation pressure data of the current oil and gas reservoir formation information and the extended oil and gas reservoir formation information as the pressure data to be measured reflecting comprehensive experimental requirements.

4. The method according to claim 3, characterized in that, In the pre - measurement configuration and processing steps, it also includes: After obtaining the reference cylinder volume and the sample cylinder volume under different pressures to be measured respectively, use the linear interpolation method to determine the reference cylinder and sample cylinder volumes under any pressure to be measured within the range of the list of data to be measured, and associate and store them in the list of data to be measured.

5. The method according to claim 1, wherein In the sample cylinder volume calibration steps, the following operations are included: B1. Temporarily disassemble the reference cylinder, connect the sample cylinder through the second connection valve (5), zero the high - precision metering pump and connect it to the second connection valve (5); B2. After evacuating, close the first control valve (1) and the second connection valve (5), and turn on the temperature control device to set the temperature to the preset experimental temperature; B3. Inject the set fluid into the sample cylinder with a precision metering pump until the pressure reaches the first pressure to be measured P after stabilization 21 , and record the volume V of the liquid pumped out by the pump when the pressure is stable 21 ; B4. Further set the pump pressure to the second pressure to be measured P 22 , and the pump continues to pump out the liquid until the pressure reaches P 22 . After the pressure stabilizes, record the volume V 22 ; Repeat the above operations until the pressure reaches the highest pressure to be measured in the list of data to be measured, and a series of P 2n , V 2n are obtained as the calibration data of the sample cylinder volume corresponding to different test pressures. Open the first control valve (1) to relieve the pressure of the experimental system.

6. The method according to claim 1, characterized in that In the target volume measurement steps, the following operations are included: C1. After test - pressing the experimental system, put the sample into the sample cylinder, then evacuate and set the required experimental temperature; C2. Close the second connection valve (5), open the first connection valve (4), and inject helium into the reference cylinder so that the initial pressure and temperature values of the balanced reference cylinder and the sample cylinder meet the experimental requirements; C3. Close the first connection valve (4), open the second connection valve (5), and record the equilibrium pressure and temperature of the reference cylinder and the sample cylinder after pressure equilibrium; C4. When the equilibrium pressure reaches the first test pressure, retrieve the reference cylinder and sample cylinder volume calibration data corresponding to this test pressure in the list of data to be measured, and use the linear interpolation calculation method to determine the corresponding test reference cylinder volume and test sample cylinder volume; C5. Furthermore, calculate the free space volume at the first test pressure according to Boyle's law; Repeat the above operations until the free space volumes corresponding to all test pressures are obtained.

7. A storage medium, characterized in that, The storage medium stores program codes that can implement the method described in any one of claims 1 to 6.

8. A volume parameter determination system for volumetric high-pressure adsorption experiments, characterized in that, The system executes the method described in any one of claims 1 to 6.

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