Experimental device and method for quantifying fluid dynamic content of condensate gas produced by CO₂ huff and puff in shale multi-scale pores

Abstract

The present invention belongs to the technical field of unconventional natural gas exploration and development, and particularly relates to a fluid dynamic content quantification experimental device for using condensate gas by CO2 huff and puff in shale multi-scale pores, which comprises a fluid injection system, a constant temperature device, a nuclear magnetic resonance analysis system and a fluid recovery system. The fluid injection system includes a first high-pressure gas source, a second high-pressure gas source, a three-way valve, a first plunger pump, a second plunger pump and a first stop valve. The nuclear magnetic resonance analysis system includes a reference kettle, a second stop valve, a low-field nuclear magnetic resonance instrument, a sample kettle, a third stop valve, a recovery kettle, a fourth stop valve, a gas chromatograph, a fifth stop valve and a computer. The fluid recovery system includes a back pressure valve and a third plunger pump. The present invention can simultaneously realize the real-time monitoring of the fluid distribution state in the shale multi-scale pore space during the dynamic process of CO2 huff and puff, realize the competitive adsorption test of CO2 and shale condensate gas components, and quantify the CO2 adsorption amount and desorption amount during the CO2 huff and puff process.

Description

Technical Field

[0001] The present invention belongs to the technical field of unconventional natural gas exploration and development, and particularly relates to a fluid dynamic content quantification experimental device and method for using carbon dioxide huff and puff to produce condensate gas in multi-scale pores of shale. Background Technique

[0002] The Jurassic continental shale condensate gas resources in the Sichuan Basin are rich and are expected to become an important formation to initiate the "continental shale gas revolution" in China. After the occurrence of retrograde condensation phase change in the condensate gas reservoir, the productivity of the gas well is greatly reduced, and it is very difficult to evaporate the condensate oil again by depletion pressure reduction production. Injecting CO 2 mining is a commonly used enhanced oil recovery method. Although the theory of injecting CO 2 mining method is relatively perfect and the technology is relatively mature in conventional condensate gas reservoirs, its application in shale condensate gas reservoirs is scarce. The applicability of the CO 2 action mechanism in conventional condensate gas reservoirs in shale condensate gas reservoirs needs to be demonstrated, and relevant theoretical understandings need to be explored. The reservoir of shale condensate gas reservoirs is rich in nano-pores and is expected to become an important target for CO 2 storage. Considering its dense reservoir characteristics, CO 2 huff and puff is a more realistic CO 2 mining method. The characteristics, effects and action mechanisms of CO 2 huff and puff to produce shale condensate gas are the keys to evaluating the enhanced oil recovery potential of CO 2 huff and puff in shale condensate gas reservoirs. However, the reservoir of shale condensate gas reservoirs is developed with nano-pores, the interfacial phenomenon is prominent, the phase change law of condensate gas is complex, and multi-scale pore spaces coexist, resulting in a complex and diverse occurrence state of reservoir fluids. The microscopic enhancement mechanism of CO 2 is unclear. Considering the law of CO 2 huff and puff to produce shale condensate gas and the microscopic enhancement mechanism under different scale pore spaces is helpful to support the analysis of shale condensate gas production law and the evaluation of CO 2 huff and puff enhanced oil recovery potential, guide the selection of shale condensate gas development methods and the optimization of production systems, and then promote the large-scale and efficient utilization of shale condensate gas resources and realize the efficient development of shale condensate gas.

[0003] At present, there is still a lack of effective experimental means to study the behavior of CO 2 huff and puff to produce shale condensate gas in multi-scale pore spaces. CO 2 Core displacement experiment is an experimental method to simulate the production process of crude oil or natural gas in underground reservoirs. By injecting CO 2 gas into the experimental device equipped with a core model, the injection process of CO 2 in the underground reservoir is simulated to study CO 2The interaction with the fluids (such as crude oil, natural gas or water) in the core and its displacement effect. However, the experimental period of this method is relatively long, the measurement accuracy is not high, and only the change in the total gas storage amount in all pore spaces of the core sample can be obtained, and it is impossible to distinguish the CO 2 enhanced oil recovery effect. The isothermal adsorption experiment of shale gas is an important means to evaluate the adsorption capacity of shale reservoirs, and can study the competitive adsorption law between CO 2 and shale gas, and evaluate the effect of CO 2 huff and puff on shale gas. In this experiment, a certain amount of CO 2 gas is injected, and at a constant temperature and different pressures, the CO 2 gas performs isothermal adsorption on the shale sample, and the gas composition and concentration data released during the adsorption process are collected by a gas analysis system to calculate the adsorption amount of the shale sample for CO 2 , so as to evaluate the competitive adsorption capacity and enhanced oil recovery effect of CO 2 . Although this experiment can quantify the adsorption amount of CO 2 and the desorption amount of shale gas during the huff and puff process of CO 2 , it still cannot distinguish the huff and puff effects of CO 2 in different-scale pore spaces. At present, some scholars add a low-field nuclear magnetic resonance instrument to the shale gas isothermal adsorption device. By measuring the nuclear magnetic resonance relaxation signal of the saturated 1H-containing fluid in the shale sample, the change of the 1H-containing fluid under different pore spaces during the huff and puff process of CO 2 can be inverted, so as to evaluate the production effect of shale gas in different-scale pore spaces by CO 2 huff and puff. Using low-field nuclear magnetic resonance technology, the migration and distribution of shale gas during the huff and puff process of CO 2 can be directly, real-time and quantitatively monitored, which has the advantages of fast and non-destructive, high-precision quantification and real-time dynamic monitoring. However, since CO 2 does not release 1H signals, the low-field nuclear magnetic resonance instrument cannot directly monitor the storage amount of CO 2 during the huff and puff process of CO 2 . Although some scholars use a low-field nuclear magnetic resonance instrument combined with a gas chromatograph to quantify the adsorption amount of CO 2 , its experimental device is limited to the study of static processes and it is difficult to study the dynamic behavior of CO 2 huff and puff. At present, the specific experimental device and method for quantitatively studying the dynamic behavior of condensate gas production by CO 2 huff and puff under different-scale shale pore spaces still need to be determined. Summary of the Invention

[0004] The purpose of the present invention is to provide a fluid dynamic content quantification experimental device and method for carbon dioxide huff-and-puff production condensate gas in multi-scale pores of shale, which can simultaneously realize CO 2 Real-time monitoring of the fluid distribution state in the multi-scale pore space of shale during the dynamic process of CO 2 Competitive adsorption test with shale condensate gas components to quantify CO 2 CO during the throughput process 2 Adsorption and desorption, evaluation of CO 2 The enhanced recovery and storage effects of huff and puff help support the CO2 condensate production of shale gas. 2 The evaluation of throughput production potential will guide the optimization of shale condensate gas production system, thereby promoting the scale and efficient utilization of shale condensate gas resources and realizing the efficient development of shale condensate gas.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A fluid dynamic content quantification experimental device for carbon dioxide inhalation and exhalation of condensate gas in multi-scale pores of shale, comprising a fluid injection system, a constant temperature device, a nuclear magnetic resonance analysis system and a fluid recovery system, characterized in that: the fluid injection system comprises a first high-pressure gas source, a second high-pressure gas source, a three-way valve, a first plunger pump, a second plunger pump and a first stop valve, the nuclear magnetic resonance analysis system is in the constant temperature device, the nuclear magnetic resonance analysis system comprises a reference kettle, a second stop valve, a low-field nuclear magnetic resonance instrument, a sample kettle, a third stop valve, a recovery kettle, a fourth stop valve, a gas chromatograph, a fifth stop valve and a computer, and the fluid recovery system comprises a back pressure valve and a third plunger pump;

[0007] The first high-pressure gas source and the second high-pressure gas source are connected through the two inlet ends of the three-way valve. The first high-pressure gas source contains C 4 H 10 The second high pressure gas source contains CO 2 , the outlet end of the three-way valve is connected to the first plunger pump and the second plunger pump respectively through pipelines, the first plunger pump and the second plunger pump are connected to the reference kettle through pipelines, the first stop valve is installed on the common pipeline of the first plunger pump and the second plunger pump, and the first emptying / vacuuming pipeline and the first pressure gauge are installed on the pipeline between the first stop valve and the reference kettle, and the first pressure gauge is used to measure the pressure of the reference kettle;

[0008] The reference kettle is connected to the sample kettle through the second stop valve. The low-field nuclear magnetic resonance instrument is installed on both sides of the sample kettle for real-time monitoring of the changes in fluid components in the sample during the test. The sample kettle is connected to the recovery kettle through the third stop valve. A secondary pipeline is also connected between the sample kettle and the recovery kettle, and the gas chromatograph is installed on this pipeline. The reference kettle is connected to the gas chromatograph through the fourth stop valve. The recovery kettle is connected to the gas chromatograph through the fifth stop valve. A thermometer is provided between the reference kettle and the sample kettle, and the thermometer is used to monitor the temperature in the constant temperature device;

[0009] The outlet end of the recovery kettle is sequentially connected to the back pressure valve and the third plunger pump. A second pressure gauge and a second evacuation / vacuum pipeline are also installed on the pipeline between the recovery kettle and the back pressure valve. The second pressure gauge is used to monitor the pressure of the recovery kettle. The low-field nuclear magnetic resonance instrument and the gas chromatograph are connected to the computer through data wires.

[0010] The first plunger pump and the second plunger pump adopt ISCO high-precision pumps, and the low-field nuclear magnetic resonance instrument is a high-temperature and high-pressure low-field nuclear magnetic resonance instrument.

[0011] The cylinders of the reference kettle and the sample kettle are made of polyether ether ketone materials that are non-magnetic, hydrogen-free, and resistant to high temperature and high pressure.

[0012] The present invention also provides an experimental method for a fluid dynamic content quantification experimental device for CO2 huff and puff to mobilize condensate gas in shale multi-scale pores. The experimental method includes the following steps:

[0013] Step S100: Pretreatment before the experiment, prepare the shale samples and shale condensate gas components required for the experiment, and check that the experimental device has no leakage and is in a normal working state;

[0014] Step S200: Determine the base signal. Since the bulk spaces such as stacked pores and free spaces contribute less to fluid adsorption, it can be approximately considered that their fluid compositions are equal to the fluid composition of the sample taken from the sample kettle measured by the gas chromatograph at equilibrium. It is planned to use an empty sample kettle to determine the base signal;

[0015] Step S300: Calibrate the hydrocarbon component quantity-fluid nuclear magnetic signal quantity. Since the bulk spaces such as stacked pores and free spaces contribute less to fluid adsorption, it can be approximately considered that their fluid compositions are equal to the fluid composition of the sample taken from the sample kettle measured by the gas chromatograph at equilibrium. It is planned to use an empty sample kettle to calibrate the relationship between the non-adsorbed hydrocarbon component quantity and the fluid nuclear magnetic signal quantity;

[0016] Step S400: Depletion production test. To restore the actual development situation, perform CO 2Before the huff and puff test, a depletion production test needs to be carried out first;

[0017] Step S500: CO 2 huff and puff test;

[0018] Step S600: Multiple rounds of CO 2 huff and puff, repeat Step S500 to conduct multiple rounds of CO 2 huff and puff simulation tests, which can explore the influence of the number of huff and puff rounds on the 2 enhancement of oil recovery and the sequestration effect by CO huff and puff.

[0019] The step S100 includes the following shale sample preparation steps:

[0020] Step S110: Collect 20 different shale samples from the target area, crush the massive shale samples using a crusher, and then grind the shale fragments using a ball mill;

[0021] Step S120: Then use a 200-mesh sieve to screen the ground particle samples, collect the shale powder smaller than 75 μm, extract the prepared shale samples, and store them after drying under vacuum.

[0022] The "baseline signal determination" in the step S200 specifically includes the following steps:

[0023] Step S210: Use a constant temperature device to restore the temperature of the entire nuclear magnetic resonance analysis system to the actual reservoir temperature condition. Then open all the valves of the experimental device, and use the first evacuation / vacuum pipeline and the second evacuation / vacuum pipeline (22) to evacuate the experimental device. The evacuation time is not less than 12 hours to remove the air in the entire system;

[0024] Step S220: After the empty sample cell is evacuated, use a low-field nuclear magnetic resonance instrument to measure the nuclear magnetic signal of the empty sample cell as the baseline signal of the empty sample cell.

[0025] The "calibration of hydrocarbon component quantity - fluid nuclear magnetic signal quantity" in the step S300 specifically includes the following steps:

[0026] Step S310: Based on the empty sample cell, open the first stop valve and the second stop valve at the front end of the sample cell, and use the fluid injection system to inject C 4 H 10 from the first high-pressure gas source into the sample cell. The first pressure gauge detects the pressure in the sample cell, and stops injecting the gas until the pressure in the sample cell reaches the target pressure;

[0027] Step S320: After C 4 H 10After being fully saturated, close the first shut-off valve, the second shut-off valve, and the first plunger pump, open the third shut-off valve, and gradually reduce the outlet pressure of the sample autoclave using the back-pressure valve and the third plunger pump, so that C in the sample autoclave 4 H 10 is discharged. In this step, measure the PVT parameters of C in the sample autoclave using a gas chromatograph. 4 H 10 Finally, subtract the nuclear magnetic base signal from the measured nuclear magnetic signal amount to obtain the nuclear magnetic signal amount of the fluid, and combine it with the hydrocarbon component amount in the stacked pores and free space measured by the gas chromatograph, so as to realize the calibration of the hydrocarbon component amount in the bulk phase space and the nuclear magnetic signal amount of the fluid.

[0028] The "depletion production test" in step S400 specifically includes the following steps:

[0029] Step S410: After calibrating the hydrocarbon component amount - nuclear magnetic signal amount of the fluid, repeat step S100 to prepare the shale particle sample, and fill the fully dried shale sample into the sample autoclave. To form a system in which the porous medium-confined fluid and the bulk fluid coexist in the sample autoclave and simulate the state of coexistence of pores and fractures in the actual reservoir, the filling amount of the shale sample in the sample autoclave does not exceed two-thirds of the autoclave capacity;

[0030] In the low-field nuclear magnetic resonance test, to avoid mutual interference of hydrogen signals of different fluids and ensure the accuracy of the test results, the first high-pressure gas source contains C 4 H 10 the typical components of shale condensate gas. During the desorption process, the shale sample is only saturated with C 4 H 10 The specific operation is as follows:

[0031] Step S421: Open the outlet of the first high-pressure gas source of the three-way valve, open the first shut-off valve and the second shut-off valve, and close the third shut-off valve. Start the first plunger pump and set the pump flow rate to 5 mL / min. Inject C in the first high-pressure gas source 4 H 10 into the reference autoclave and the sample autoclave, and monitor the internal pressure of the reference autoclave and the sample autoclave through the first pressure gauge until the internal pressure of the sample autoclave reaches the actual pressure condition of the target reservoir;

[0032] Step S422: Close the outlet of the first high-pressure gas source of the three-way valve, close the first shut-off valve and the second shut-off valve, and let the experimental device stand for 6 h to allow the injected C 4 H 10 to fully contact the shale sample and fully restore the original occurrence state of hydrocarbon fluid molecules under the actual target reservoir conditions;

[0033] Step S423: Wait for C 4 H 10After being in full contact with the shale sample, open the third shut-off valve, and use the fluid backpressure system to gradually reduce the outlet pressure of the sample autoclave until the pressure value monitored by the second pressure gauge of the fluid backpressure system reaches the set value, and discharge the C in the sample autoclave. 4 H 10 , and complete the depletion production test.

[0034] In the step S500, the "CO 2 huff and puff test" specifically includes the following steps:

[0035] Step S510: After the depletion production test, close the second shut-off valve and the third shut-off valve at both ends of the sample autoclave, and open all the remaining valves on the pipeline. Use the first evacuation / vacuum pipeline and the second evacuation / vacuum pipeline to evacuate and vacuum the gas in the entire experimental device except the sample autoclave, so as to avoid the influence of the residual gas during the depletion production test on the nuclear magnetic resonance relaxation results of hydrocarbon components.

[0036] Step S520: Close all the valves on the pipeline, open the outlet of the second high-pressure gas source of the three-way valve, open the first shut-off valve, and start the second plunger pump to inject the CO 2 in the second high-pressure gas source into the reference autoclave. Monitor through the first pressure gauge that the internal pressure of the reference autoclave is higher than the internal pressure of the sample autoclave. In this step, the internal pressure of the sample autoclave is the pressure value monitored by the second pressure gauge after the depletion production test in step S400, so as to realize the simulation test of "injection" of CO 2 . After the CO 2 injection is balanced, close the outlet of the second high-pressure gas source of the three-way valve, close the first shut-off valve, and read the internal pressure of the reference autoclave after balance through the first pressure gauge. At this time, the fluid pressure in the reference autoclave is the injection pressure of CO 2 . By changing the fluid pressure in the reference autoclave through the fluid injection system, the influence of the CO2 injection pressure on the enhanced oil recovery and storage effect of CO 2 huff and puff can be explored.

[0037] Step S530: After the CO 2 injection is completed, close the first shut-off valve and open the second shut-off valve. Since the internal pressure of the reference autoclave is higher than the internal pressure of the sample autoclave, the CO 2 enters the sample autoclave from the reference autoclave under the action of the pressure difference until it is fully balanced, so as to realize the simulation test of "swallow" of CO 2 ;

[0038] Step S540: Close the second shut-off valve and let the nuclear magnetic resonance analysis test system stand for 6 h to enable the CO 2 to fully diffuse and mass transfer in the shale medium, so as to realize the simulation test of "simmer" of CO 2 ;

[0039] Step S550: CO 2After the "stewing" process is balanced, the pressure in the sample kettle after equilibrium is read through the first pressure gauge. In this process, the effect of stewing time on CO can be explored by controlling the standing time. 2 Finally, the third stop valve is opened, and the pressure at the outlet is controlled by the back pressure valve and the third plunger pump to be lower than the pressure in the sample kettle, so that the fluid in the sample kettle is output to the recovery kettle, realizing CO 2 A simulated test of "vomiting".

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. Conventional low-field NMR testing can only test rock samples without temperature and pressure loading, which is far from the high temperature and high pressure environment of actual rock samples in deep reservoirs. It can also only test fluids containing 1H. 2 It is difficult to detect fluids that do not contain 1H, and conventional gas chromatography analysis can only simply quantify the total gas volume of each component fluid, and cannot accurately quantify the content of each component fluid in different storage spaces, and the measurement accuracy is low. The present invention innovates a set of experimental devices, which can simulate the dynamic processes of adsorption, displacement, throughput and desorption of hydrocarbon components by equipping a combined reference kettle, a sample kettle, a recovery kettle, a high-temperature and high-pressure low-field nuclear magnetic resonance analyzer and a gas chromatograph, and can monitor the fluid migration law in the above dynamic process in real time, and can also quantify the dynamic content of various fluids in the multi-scale pore space of the above dynamic process, and study the multi-component competitive adsorption characteristics;

[0042] 2. The present invention has innovated a set of experimental and analytical methods. It intends to use the above innovative experimental device, combined with a high temperature and high pressure low field nuclear magnetic resonance instrument and a gas chromatograph, to accurately determine CO 2 CO in the dynamic process of throughput 2 Adsorption amount, CO 2 The desorption amount and the production amount of shale condensate gas components are used to quantitatively evaluate the CO 2 Effect of Huff and Puff on EOR and CO 2 Storage effect, quantitative analysis of CO 2 Injection pressure, well shut-in time, and number of cycles of CO 2 Throughput parameters for CO 2 The effect of huff and puff can realize the multi-scale pore CO 2 Quantification of fluid dynamic content during the huff-and-puff production of condensate gas helps support the development of shale condensate gas CO 2 The evaluation of throughput production potential can guide the optimization of shale condensate gas production system, thereby achieving efficient development of shale condensate gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention is further illustrated by means of the non-limiting examples given in the accompanying drawings.

[0044] Figure 1 Structural schematic diagram of the experimental device of the present invention;

[0045] Figure 2 Schematic flow diagram of the experimental method of the present invention;

[0046] Figure 3 is CO 2 Schematic flow diagram of the analysis process of the "swallowing" and "stewing" action characteristics;

[0047] Figure 4 is CO 2 Schematic flow diagram of the analysis process of the "spitting" action characteristics;

[0048] Descriptions of the main component symbols are as follows:

[0049] The first high-pressure gas source 1, the second high-pressure gas source 2, the three-way valve 3, the first plunger pump 4, the second plunger pump 5, the first stop valve 6, the first evacuation / vacuum pipeline 7, the first pressure gauge 8, the reference kettle 9, the thermometer 10, the second stop valve 11, the low-field nuclear magnetic resonance instrument 12, the sample kettle 13, the third stop valve 14, the recovery kettle 15, the fourth stop valve 16, the gas chromatograph 17, the fifth stop valve 18, the computer 19, the constant temperature device 20, the second pressure gauge 21, the second evacuation / vacuum pipeline 22, the back pressure valve 23, the third plunger pump 24. Specific embodiments

[0050] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0051] Example 1:

[0052] As Figure 1 shown, a fluid dynamic content quantification experimental device for CO2 huff and puff to produce condensate gas in shale multi-scale pores includes a fluid injection system, a constant temperature device 20, a nuclear magnetic resonance analysis system, and a fluid recovery system, and is characterized in that: the fluid injection system includes a first high-pressure gas source 1, a second high-pressure gas source 2, a three-way valve 3, a first plunger pump 4, a second plunger pump 5, and a first stop valve 6, the nuclear magnetic resonance analysis system is located in the constant temperature device 20, and the nuclear magnetic resonance analysis system includes a reference kettle 9, a second stop valve 11, a low-field nuclear magnetic resonance instrument 12, a sample kettle 13, a third stop valve 14, a recovery kettle 15, a fourth stop valve 16, a gas chromatograph 17, a fifth stop valve 18, and a computer 19, and the fluid recovery system includes a back pressure valve 23 and a third plunger pump 24;

[0053] The first high-pressure gas source 1 and the second high-pressure gas source 2 are connected through two inlet ends of the three-way valve 3, and the first high-pressure gas source 1 contains C 4 H 10, the second high-pressure gas source 2 contains CO 2 , the outlet end of the three-way valve 3 is connected to the first plunger pump 4 and the second plunger pump 5 through pipelines respectively. The first plunger pump 4 and the second plunger pump 5 are jointly connected to the reference kettle 9 through pipelines. The first stop valve 6 is installed on the common pipeline of the first plunger pump 4 and the second plunger pump 5. A first evacuation / vacuum pipeline 7 and a first pressure gauge 8 are installed on the pipeline between the first stop valve 6 and the reference kettle 9. The first pressure gauge 8 is used to measure the pressure of the reference kettle 8;

[0054] The reference kettle 9 is connected to the sample kettle 13 through the second stop valve 11. The low-field nuclear magnetic resonance spectrometer 12 is installed on both sides of the sample kettle 13 for real-time monitoring of the changes in the fluid components in the sample during the test. The sample kettle 13 is connected to the recovery kettle 15 through the third stop valve 14. A secondary pipeline is also connected between the sample kettle 13 and the recovery kettle 15 and the gas chromatograph 17 is installed on this pipeline. The reference kettle 9 is connected to the gas chromatograph 17 through the fourth stop valve 16. The recovery kettle 15 is connected to the gas chromatograph 17 through the fifth stop valve 18. A thermometer 10 is arranged between the reference kettle 9 and the sample kettle 13. The thermometer 10 is used to monitor the temperature in the constant temperature device 20;

[0055] The outlet end of the recovery kettle 15 is successively connected to the back pressure valve 23 and the third plunger pump 24. A second pressure gauge 21 and a second evacuation / vacuum pipeline 22 are also installed on the pipeline between the recovery kettle 15 and the back pressure valve 23. The second pressure gauge 21 is used to monitor the pressure of the recovery kettle 15. The low-field nuclear magnetic resonance spectrometer 12 and the gas chromatograph 17 are connected to the computer 19 through data wires.

[0056] As a further preference of this embodiment, the first plunger pump 4 and the second plunger pump 5 adopt ISCO high-precision pumps, and the low-field nuclear magnetic resonance spectrometer 12 is selected as a 23MHZ high-temperature and high-pressure low-field nuclear magnetic resonance spectrometer. This device consists of a nuclear magnetic coil and a permanent magnet and can real-time monitor the changes in the fluid components in the sample during the test.

[0057] As a further preference of this embodiment, the cylinders of the reference kettle and the sample kettle are made of polyether ether ketone materials that are non-magnetic, hydrogen-free, and resistant to high temperature and high pressure.

[0058] Example 2:

[0059] Based on the experimental device provided in Example 1, corresponding experimental methods are proposed. As Figure 2 shown, in this embodiment, the volume of the reference kettle 9 is 100 ml, the volume of the sample kettle 13 is 200 ml, and the volume of the recovery kettle 15 is 100 ml.

[0060] The experimental method includes the following steps:

[0061] Step S100: Pre-treatment before the experiment. Prepare the shale samples and shale condensate gas components required for the experiment, check that the experimental device has no leaks and is in normal working condition, clean the experimental bench and experimental instruments to ensure a safe and clean experimental environment. In this step, the preparation steps of the shale samples are as follows:

[0062] Step S110: Collect 20 different shale samples from the target area with TOC > 2%. Use a crusher to crush the massive shale samples, and then use a ball mill to grind the shale fragments.

[0063] Step S120: Then use a 200-mesh sieve to screen the ground particle samples, collect the shale powder smaller than 75 μm, extract the prepared shale samples, and dry them under vacuum and store them.

[0064] Step S200: Determine the base signal. Since the bulk spaces such as stacked pores and free spaces contribute little to fluid adsorption, it can be approximately considered that their fluid compositions are equal to the fluid compositions of the samples taken from the sample cell measured by the gas chromatograph at equilibrium. It is planned to use the empty sample cell 13 to determine the base signal. In this step, the empty sample cell 13 refers to the sample cell 13 without shale samples filled. In this step, the following operation steps are specifically included:

[0065] Step S210: Use the temperature control device (20) to restore the temperature of the entire nuclear magnetic resonance analysis system to the actual reservoir temperature condition. Then open all the valves of the experimental device, and use the first evacuation / vacuum line (7) and the second evacuation / vacuum line (22) to evacuate the experimental device. The evacuation time is not less than 12 hours to eliminate the air in the entire system and avoid its influence on the nuclear magnetic resonance relaxation results of hydrocarbon components.

[0066] Step S220: In order to eliminate the interference of substances containing 1H (a kind of isotope of hydrogen, protium) in the sample cell material on the fluid nuclear magnetic signal, after evacuating the empty sample cell (13), use the low-field nuclear magnetic resonance instrument (12) to measure the nuclear magnetic signal of the empty sample cell (13) as the base signal of the empty sample cell (13).

[0067] Step S300: Calibrate the relationship between the amount of hydrocarbon components and the fluid nuclear magnetic signal. Since the bulk spaces such as stacked pores and free spaces contribute little to fluid adsorption, it can be approximately considered that their fluid compositions are equal to the fluid compositions of the samples taken from the sample cell 13 measured by the gas chromatograph 17 at equilibrium. It is planned to use the empty sample cell 13 to calibrate the relationship between the amount of non-adsorbed hydrocarbon components and the fluid nuclear magnetic signal. In this step, the following operation steps are specifically included:

[0068] Step S310: Based on the empty sample cell 13, open the first stop valve 6 and the second stop valve 11 at the front end of the sample cell 13, and use the fluid injection system to pump C through the first plunger pump 4 4 H10 Inject into the sample autoclave 13 from the first high-pressure gas source 1. The first pressure gauge 8 detects the pressure inside the sample autoclave 13 until the pressure inside the sample autoclave 13 reaches the target pressure, and then stops injecting the gas.

[0069] Step S320: After C 4 H 10 in the sample autoclave 13 is fully saturated, close the first stop valve 6, the second stop valve 11, and the first plunger pump 4, open the third stop valve 14, and gradually reduce the outlet pressure of the sample autoclave 13 by using the backpressure valve 23 and the third plunger pump 24, so that C 4 H 10 inside the sample autoclave 13 is discharged. In this step, use the gas chromatograph 17 to measure the PVT parameters of C 4 H 10 inside the sample autoclave 13. Finally, subtract the nuclear magnetic base signal from the measured nuclear magnetic signal amount to obtain the nuclear magnetic signal amount of the fluid, and combine it with the hydrocarbon component amount in the stacked pores and free space measured by the gas chromatograph 17, so as to realize the calibration of the hydrocarbon component amount in the bulk phase space and the nuclear magnetic signal amount of the fluid.

[0070] Step S400: Depletion production test. To restore the actual development situation, a depletion production test needs to be carried out before the CO2 huff and puff test; in this step, it specifically includes the following operation steps:

[0071] Step S410: After calibrating the hydrocarbon component amount - nuclear magnetic signal amount of the fluid, repeat Step S100 to prepare the shale particle sample, and fill the fully dried shale sample into the sample autoclave 13. To form a system in which the porous medium-confined fluid and the bulk fluid coexist in the sample autoclave 13 and simulate the state of coexistence of pores and fractures in the actual reservoir, the filling amount of the shale sample in the sample autoclave 13 does not exceed two-thirds of the capacity of the sample autoclave 13.

[0072] Step S420: In the low-field nuclear magnetic resonance test, to avoid the mutual interference of the hydrogen-containing signals of different fluids and ensure the accuracy of the test results, the first high-pressure gas source 1 contains C 4 H 10 the typical components of shale condensate gas. During the desorption process, the shale sample is only saturated with C 4 H 10 . The specific operation is as follows:

[0073] Step S421: Open the outlet of the first high-pressure gas source 1 of the three-way valve 3, open the first stop valve 6 and the second stop valve 11, and close the third stop valve 14. Start the first plunger pump 4 and set the flow rate of the pump to 5 mL / min. Inject C 4 H 10Inject into the reference kettle 9 and the sample kettle 13. Monitor the internal pressures of the reference kettle 9 and the sample kettle 13 through the first pressure gauge 8 until the internal pressure in the sample kettle 13 reaches 48 MPa of the actual pressure condition of the target reservoir.

[0074] Step S422: Close the outlet of the first high-pressure gas source 1 of the three-way valve 3, close the first stop valve 6 and the second stop valve 11, and leave the experimental device static for 6 h to allow the injected C 4 H 10 to fully contact the shale sample and fully restore the original occurrence state of hydrocarbon fluid molecules under the actual target reservoir conditions.

[0075] Step S423: After C 4 H 10 has fully contacted the shale sample, open the third stop valve 14, and use the fluid backpressure system to gradually reduce the outlet pressure of the sample kettle 13 until the pressure value monitored by the second pressure gauge 21 of the fluid backpressure system reaches 10 MPa, and discharge the C 4 H 10 in the sample kettle 13 to complete the depletion production test.

[0076] Step S500: CO 2 huff and puff test; in this step, it specifically includes the following steps:

[0077] Step S510: After the depletion production test, close the second stop valve 11 and the third stop valve 14 at both ends of the sample kettle 13, and open all the other valves on the pipeline. Use the first evacuation / vacuum pipeline 7 and the second evacuation / vacuum pipeline 22 to evacuate and vacuum the gas in the entire experimental device except the sample kettle 13 to avoid the influence of the residual gas during the depletion production test on the nuclear magnetic resonance relaxation results of hydrocarbon components.

[0078] Step S520: Close all the valves on the pipeline, open the outlet of the second high-pressure gas source 2 of the three-way valve 3, open the first stop valve 6, start the second plunger pump 5, set the flow rate of the pump to 5 mL / min, and inject the CO 2 in the second high-pressure gas source 2 into the reference kettle 9. Monitor the internal pressure of the reference kettle 9 through the first pressure gauge 8 to reach 30 MPa, which is higher than the internal pressure of the sample kettle 13. In this step, the internal pressure of the sample kettle 13 is the 10 MPa pressure value monitored by the second pressure gauge 21 after the depletion production test in Step S400, so as to realize the simulation test of "injection" of CO 2 . After the injection of CO 2 is balanced, close the outlet of the second high-pressure gas source 2 of the three-way valve 3, close the first stop valve 6, and read the internal pressure of the reference kettle 9 after balance through the first pressure gauge 8. At this time, the fluid pressure in the reference kettle 9 is the injection pressure of CO 2 . By changing the fluid pressure in the reference kettle 9 through the fluid injection system, the exploration of CO2 Effect of injection pressure on enhanced oil recovery and sequestration effect by CO2 huff and puff

[0079] Step S530: CO 2 After the injection is completed, close the first shut-off valve 6 and open the second shut-off valve 11. Since the internal pressure of the reference autoclave 9 reaches 30 MPa, which is higher than the internal pressure of 10 MPa in the sample autoclave 13, CO 2 enters the sample autoclave 13 from the reference autoclave 9 under the action of the pressure difference until full equilibrium is achieved, realizing the simulation test of "swallowing" CO 2 ;

[0080] Step S540: Close the second shut-off valve 11 and let the nuclear magnetic resonance analysis test system stand for 6 h to allow CO 2 to fully diffuse and mass transfer in the shale medium, realizing the simulation test of "soaking" CO 2 ;

[0081] Step S550: CO 2 After the "soaking" process reaches equilibrium, read the pressure in the sample autoclave 13 after equilibrium as 20 MPa through the first pressure gauge 8. During this process, by controlling the standing time, the influence of the soaking well time on enhanced oil recovery and sequestration effect by CO 2 huff and puff can be explored. Finally, open the third shut-off valve 14, and cooperate with the back pressure valve 23 and the third plunger pump 24 to control the pressure at the outlet end to be lower than the pressure in the sample autoclave 13, so that the fluid in the sample autoclave 13 flows out to the recovery autoclave 15, realizing the simulation test of "spitting" CO 2 ;

[0082] Step S600: Multiple rounds of CO 2 huff and puff, repeat step S500 to carry out simulation tests of multiple rounds of CO 2 huff and puff, and the influence of the number of huff and puff rounds on enhanced oil recovery and sequestration effect by CO 2 huff and puff can be explored.

[0083] Example 3:

[0084] In order to explore the enhanced oil recovery effect and sequestration law of CO 2 , as well as the competitive adsorption characteristics between CO 2 and typical components of shale condensate gas, it is necessary to accurately quantify the CO 2 adsorption amount and desorption amount in the sample during the CO2 huff and puff process. Since CO 2 does not release nuclear magnetic resonance signals, it is proposed to combine a low-field nuclear magnetic resonance analyzer and a gas chromatograph to clarify the competitive adsorption characteristics between CO 2 and shale condensate gas components by identifying and quantifying the changes in CO 2 in different storage spaces in the sample autoclave before and after the CO 2 huff and puff process, and clarify the competitive adsorption characteristics between CO2 For the production effect of shale condensate gas components, evaluate the geological storage effect of CO 2 Based on the CO 2 huff and puff characteristics analysis of Figure 3 and Figure 4 as shown:

[0085] ① After the balance of "injection", "swallowing", "soaking" and "production" in the CO 2 experimental process, use the gas chromatograph 17 to sample and measure the composition of the mixed fluid in the reference kettle 9, the sample kettle 13 and the recovery kettle 15 respectively. In order to avoid the influence of the sampling of the gas chromatograph 17 on the fluid composition in each kettle, the sampling volume each time does not exceed 10 μL, and the sample filling volume in the sample kettle does not exceed two-thirds of the kettle capacity;

[0086] ② CO 2 Analysis of the characteristics of "swallowing" and "soaking":

[0087] After filling the shale sample, the fluid storage space in the sample kettle 13 includes the confined pores inside the shale particles, the stacked pores between the shale particles and the unfilled free space. The stacked pores and the free space contribute less to the fluid adsorption. It can be approximately considered that the fluid composition at equilibrium is equal to the fluid composition of the sample kettle sampled by the gas chromatograph 17. Assume:

[0088] The total pressure of CO 2 in the reference kettle 9 after "injection" is p 1 ;

[0089] The total pressure of CO 2 in the reference kettle 9 after the balance of "swallowing" and "soaking" is p 2 ;

[0090] The total pressure of CO 2 in the sample kettle 13 before "swallowing" and "soaking" is p 0 ;

[0091] The C 2 outside the confined pores of the sample particles in the sample kettle 13 after "swallowing" and "soaking" 4 H 10 mole composition is x 2 .

[0092] The C 4 H 10 content outside the confined pores of the sample particles in the sample kettle 13 is equal to the sum of the C 4 H 10 contents in the stacked pores and the free space, and can be obtained by converting the signal peak area corresponding to the low-field nuclear magnetic resonance T2 spectrum of the fluid in the sample kettle 13. The calculation formula is expressed as:

[0093]

[0094] In the formula, n 1 is the content of the condensate gas component outside the confined pores of the sample particles in the sample autoclave, g is the calibration relationship function between the content of the condensate gas component and the integral area of the nuclear magnetic signal peak, S is the integral area of the nuclear magnetic signal peak, p 1 represents the signal peak of the condensate gas component in the stacked pores of the shale sample, p 2 represents the signal peak of the condensate gas component in the unfilled free space.

[0095] The CO 2 content in the stacked pores and free space in the sample autoclave 13 is proportional to the CO 2 mole fraction measured by sampling in the sample autoclave 13, and the calculation formula is expressed as:

[0096]

[0097] In the formula, n 2 is the CO 2 content in the stacked pores and free space in the sample autoclave.

[0098] By recording the pressure in the sample autoclave 13 after depletion production, and the changes in pressure and fluid composition in the sample autoclave 13 and the reference autoclave 9 before and after the "swallowing" and "stewing" processes, combined with the equation of state, the C 2 content in the sample autoclave 13 after depletion production and the reduced CO 4 H 10 content in the reference autoclave 9 can be calculated. The calculation formula can be expressed as: 2 N

[0099] N Cn,t = N 1 (p 0 , V 2 , T);

[0100]

[0101] Among them, N Cn,t is the condensate gas content in the sample autoclave 13 after depletion production, is the reduced CO 2 content in the reference autoclave 9 after injecting CO 2 ; N 1 is the equation of state of the condensate gas component, N 2 is the equation of state of CO 2 ; p 0 is the total pressure before the "swallowing" and "stewing" of CO 2 , p 1 is the total pressure after the "injection" of CO 2 , V1 is the volume of the reference kettle 9, V 2 is the difference between the volume of the sample kettle 13 and the volume of the shale sample, and T is the ambient temperature of the entire nuclear magnetic resonance analysis system.

[0102] According to the law of conservation of matter, the reduced CO 2 content in the reference kettle 13 is equal to the CO 2 content entering the sample kettle 13. Therefore, the fluid adsorption amount in the confined pores within the sample particles in the sample kettle 13 is equal to the total fluid component content in the sample kettle 13 minus the fluid content in the storage space outside the shale confined pores in the sample kettle 13. The calculation formula is expressed as:

[0103] N Cn = N Cn,t - n 1 ;

[0104]

[0105] Among them, N Cn is the adsorbed amount of condensate gas components in the shale confined pores in the sample kettle after "swallowing" and "simmering" of CO 2 ; is the adsorbed amount of CO 2 in the shale confined pores in the sample kettle after "swallowing" and "simmering" of CO 2 .

[0106] In order to quantify the competitive adsorption ability of CO 2 and C 4 H 10 , it is planned to combine the determined adsorbed amounts of CO 2 and C 4 H 10 and the mixed component composition, and calculate the selective adsorption coefficient of CO 2 and C 4 H 10 in the sample. The calculation formula is expressed as:

[0107]

[0108] In the formula, S is the selective adsorption coefficient of CO 2 and the shale condensate gas components.

[0109] ③ Analysis of the characteristics of the "spit" effect of CO 2 :

[0110] During the "spit" process of CO 2 , by recording the changes in pressure and fluid composition in the recovery kettle 15, referring to the above ideas, the desorbed amount and sealed amount of CO 2 in the sample can be calculated. After the "spit" process of CO 2 reaches equilibrium, assume:

[0111] In the sample autoclave 13, the C 4 H 10 mole fraction is x 3 ;

[0112] The total pressure in the recovery autoclave 15 is p 4 , C 4 H 10 mole fraction is x 4 ;

[0113] The C outside the confined pores of the shale sample in the sample autoclave 13 4 H 10 content is equal to the sum of the C in the stacked pores and free space 4 H 10 content, which can be obtained by converting the signal peak area corresponding to the low-field nuclear magnetic resonance T2 spectrum of the fluid in the sample autoclave 13. The calculation formula can also be expressed as:

[0114]

[0115] where n 3 is the content of the condensate gas component outside the confined pores of the sample particles in the sample autoclave 13;

[0116] Similarly, after the "exhalation" equilibrium of CO 2 , the CO content in the stacked pores and free space in the sample autoclave 13 2 is proportional to the mole fraction of CO measured in the sample taken from the sample autoclave 13. The calculation formula can be expressed as: 2

[0117]

[0118] In the formula, n 4 is the CO content in the stacked pores and free space in the sample autoclave 13 2 ;

[0119] By recording the pressure and fluid composition in the recovery autoclave 15 after the CO 2 "exhalation" process and combining with the equation of state, the increased C 4 H 10 content and CO 2 content in the recovery autoclave 15 can be calculated. The calculation formula can be specifically expressed as:

[0120] N' Cn,t = N 1 (p 4 × x 4 , V 3 , T);

[0121]

[0122] Among them, N' Cn,t is the content of condensate gas in the recovery kettle after "spitting" for CO 2 ; is the content of CO 2 in the recovery kettle after "spitting"; V 2 is the volume of the recovery kettle. 3 According to the law of conservation of matter, the total content of fluid components reduced in the sample kettle 13 is equal to the content of fluid components increased in the recovery kettle 15. Therefore, the amount of fluid desorbed from the shale-confined pores in the sample kettle 13 is equal to the content of fluid components increased in the recovery kettle 15 minus the amount of fluid reduced in the storage space outside the shale-confined pores in the sample kettle 13. The calculation formula can be expressed as:

[0123]

[0124] N' Cn = N' Cn,t -(n 1 - n 3 );

[0125]

[0126] In the formula, N' Cn is the desorption amount of condensate gas components in the shale-confined pores in the sample kettle after "spitting" balance for CO 2 ; is the desorption amount of CO 2 in the shale-confined pores in the sample kettle after "spitting" balance; (n 2 - n 1 ) represents the reduction amount of condensate gas components in the storage space outside the shale-confined pores in the sample kettle, and (n 3 - n 2 ) represents the reduction amount of CO 4 in the storage space outside the shale-confined pores in the sample kettle; 2

[0127] In order to quantify the geological storage effect of CO 2 , it is planned to calculate the adsorption storage rate of CO 2 in the sample by combining the desorption amount of CO 2 determined above. The calculation formula can be expressed as:

[0128]

[0129] In the formula, η is the adsorption storage rate of CO 2 .

[0130] The above embodiments are only used to exemplarily illustrate the principles and effects of the present invention, rather than to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An experimental device for quantifying the fluid dynamic content of carbon dioxide huff-and-puff condensate gas in multi-scale pores of shale, comprising a fluid injection system, a constant temperature device, a nuclear magnetic resonance analysis system and a fluid recovery system, characterized in that: The fluid injection system includes a first high-pressure gas source, a second high-pressure gas source, a three-way valve, a first plunger pump, a second plunger pump and a first stop valve. The nuclear magnetic resonance analysis system is in the constant temperature device. The nuclear magnetic resonance analysis system includes a reference kettle, a second stop valve, a low-field nuclear magnetic resonance instrument, a sample kettle, a third stop valve, a recovery kettle, a fourth stop valve, a gas chromatograph, a fifth stop valve and a computer. The fluid recovery system includes a back pressure valve and a third plunger pump; The first high-pressure gas source and the second high-pressure gas source are connected through two inlet ends of the three-way valve. The first high-pressure gas source contains C4H 10 , the second high-pressure gas source contains CO2, the outlet end of the three-way valve is connected to the first plunger pump and the second plunger pump through pipelines, the first plunger pump and the second plunger pump are connected to the reference kettle through pipelines, the first stop valve is installed on the common pipeline of the first plunger pump and the second plunger pump, and the first emptying / vacuuming pipeline and the first pressure gauge are installed on the pipeline between the first stop valve and the reference kettle, and the first pressure gauge is used to measure the pressure of the reference kettle; The reference kettle is connected to the sample kettle through the second stop valve, the low-field nuclear magnetic resonance instrument is installed on both sides of the sample kettle, and is used to monitor the changes in fluid components in the sample during the test process in real time, the sample kettle and the recovery kettle are connected through the third stop valve, a secondary pipeline is also connected between the sample kettle and the recovery kettle, and the gas chromatograph is installed on the pipeline, the reference kettle and the gas chromatograph are connected through the fourth stop valve, the recovery kettle and the gas chromatograph are connected through the fifth stop valve, a thermometer is arranged between the reference kettle and the sample kettle, and the thermometer is used to monitor the temperature in the constant temperature device; The outlet end of the recovery kettle is connected to the back-pressure valve and the third plunger pump in sequence. A second pressure gauge and a second emptying / vacuuming pipeline are also installed on the pipeline between the recovery kettle and the back-pressure valve. The second pressure gauge is used to monitor the pressure of the recovery kettle. The low-field nuclear magnetic resonance instrument and the gas chromatograph are connected to the computer through data wiring.

2. The experimental device for quantifying the fluid dynamic content of carbon dioxide inhalation and exhalation of condensate gas in multi-scale pores of shale according to claim 1, characterized in that: The first plunger pump and the second plunger pump are ISCO high-precision pumps, and the low-field nuclear magnetic resonance instrument is a high-temperature and high-pressure low-field nuclear magnetic resonance instrument.

3. The experimental device for quantifying the fluid dynamic content of carbon dioxide huff-and-puff condensate gas in multi-scale pores of shale according to claim 2, characterized in that: The cylinders of the reference kettle and the sample kettle are made of polyetheretherketone material which is non-magnetic, hydrogen-free, and resistant to high temperature and high pressure.

4. An experimental method using the fluid dynamic content quantification experimental device for carbon dioxide huff-and-puff production condensate gas in multi-scale pores of shale as claimed in any one of claims 1 to 3, characterized in that: The experimental method comprises the following steps: Step S100: pre-processing before the experiment, preparing the shale samples and shale condensate gas components required for the experiment, and checking that the experimental device has no leakage and is in normal working condition; Step S200: Determine the base signal. Since the bulk phase space such as stacked pores and free space contributes less to fluid adsorption, it can be considered that the fluid composition thereof is equal to the sampled fluid composition of the sample kettle measured by the gas chromatograph at equilibrium. It is intended to use an empty sample kettle to determine the base signal. Step S300: Calibrate the hydrocarbon component amount-fluid NMR signal amount. Since the bulk phase space such as stacked pores and free space contributes less to fluid adsorption, it can be considered that the fluid composition is equal to the sampled fluid composition of the sample kettle measured by the gas chromatograph at equilibrium. It is planned to use an empty sample kettle to calibrate the relationship between the non-adsorbed hydrocarbon component amount and the fluid NMR signal amount. Step S400: exhaustion mining test. To restore the actual development situation, exhaustion mining test must be performed before CO2 huff and puff test. Step S500: CO2 throughput test; Step S600: multiple rounds of CO2 throughput, repeating step S500, and conducting multiple rounds of CO2 throughput simulation tests to explore the impact of throughput rounds on CO2 throughput to enhance oil recovery and storage effects.

5. The experimental method according to claim 4, characterized in that: The step S100 includes the following shale sample preparation steps: Step S110: Collect 20 different shale samples from the target area, crush the blocky shale samples using a crusher, and then grind the shale fragments using a ball mill; Step S120: Then, the ground particle sample is screened using a 200-mesh sieve to collect shale powder smaller than 75 μm, and then the prepared shale sample is extracted and stored after being dried under vacuum.

6. The experimental method according to claim 5, characterized in that: The "base signal determination" in step S200 specifically includes the following steps: Step S210: using a thermostat to restore the temperature of the entire NMR analysis system to the actual reservoir temperature, then opening all valves of the experimental device, and evacuating the experimental device using the first evacuation / vacuuming pipeline and the second evacuation / vacuuming pipeline, the evacuation time is not less than 12 hours to eliminate the air in the entire system; Step S220: After the empty sample kettle is evacuated, a low-field nuclear magnetic resonance instrument is used to measure the nuclear magnetic signal of the empty sample kettle as a base signal of the empty sample kettle.

7. The experimental method according to claim 6, characterized in that: The "calibrating hydrocarbon component amount-fluid nuclear magnetic resonance signal amount" in step S300 specifically includes the following steps: Step S310: Based on the empty sample kettle, open the first stop valve and the second stop valve at the front end of the sample kettle, and use the fluid injection system to inject C4H 10 Injecting gas from a first high-pressure gas source into the sample kettle, and using a first pressure gauge to detect the pressure in the sample kettle until the pressure in the sample kettle reaches a target pressure and then the injection of gas is stopped; Step S320: Wait for C4H in the sample kettle 10 After full saturation, close the first stop valve, the second stop valve and the first plunger pump, open the third stop valve, and use the back pressure valve and the third plunger pump to gradually reduce the outlet pressure of the sample kettle to make the C4H 10 In this step, the C4H 10 The PVT parameters are obtained, and finally, the NMR base signal is deducted from the measured NMR signal to obtain the fluid NMR signal. Combined with the hydrocarbon component amounts in the stacked pores and free space measured by the gas chromatograph, the calibration of the hydrocarbon component amounts in the bulk space and the fluid NMR signal is achieved.

8. The experimental method according to claim 7, characterized in that: The "depletion mining test" in step S400 specifically includes the following steps: Step S410: after calibrating the hydrocarbon component amount-fluid NMR signal amount, repeat step S100 to prepare shale particle samples, and fill the fully dried shale samples into the sample kettle, so as to form a system in which porous medium confined fluid and bulk fluid coexist in the sample kettle, and simulate the state in which pores and fractures coexist in the actual reservoir. The amount of shale sample filled in the sample kettle shall not exceed two-thirds of the capacity of the sample kettle; Step S420: In the low-field nuclear magnetic resonance test, in order to avoid mutual interference between hydrogen-containing signals of different fluids and ensure the accuracy of the test results, the first high-pressure gas source is filled with C4H 10 Typical components of shale condensate gas. During the desorption process, the shale sample is only replaced by C4H 10 Saturation, the specific operation is: Step S421: Open the outlet of the first high-pressure gas source of the three-way valve, open the first stop valve and the second stop valve, and close the third stop valve, start the first plunger pump, set the pump flow rate to 5 mL / min, and transfer the C4H 10 Inject into the reference kettle and the sample kettle, and monitor the internal pressure of the reference kettle and the sample kettle through the first pressure gauge until the internal pressure of the sample kettle reaches the actual pressure condition of the target reservoir; Step S422: Close the outlet of the first high-pressure gas source of the three-way valve, close the first stop valve and the second stop valve, and let the experimental device stand for 6 hours to allow the injected C4H 10 Fully contact with shale samples to fully restore the original occurrence state of hydrocarbon fluid molecules under actual target reservoir conditions; Step S423: Wait for C4H 10 After the shale sample is fully in contact, the third stop valve is opened, and the outlet pressure of the sample kettle is gradually reduced by the fluid back pressure system until the pressure value monitored by the second pressure gauge of the fluid back pressure system reaches the set value, and the C4H2O2 in the sample kettle is discharged. 10 , completed the depletion mining test.

9. The experimental method according to claim 8, characterized in that: The "CO2 throughput test" in step S500 specifically includes the following steps: Step S510: After the exhaustion production test, close the second stop valve and the third stop valve at both ends of the sample kettle, open all other valves on the pipeline, and use the first emptying / vacuuming pipeline and the second emptying / vacuuming pipeline to evacuate and vacuum the gas in the entire experimental device except the sample kettle to avoid the residual gas in the exhaustion production test from affecting the NMR relaxation results of the hydrocarbon components; Step S520: Close all valves on the pipeline, open the outlet of the second high-pressure gas source of the three-way valve, open the first stop valve, start the second plunger pump, and inject the CO2 in the second high-pressure gas source into the reference kettle. The internal pressure of the reference kettle monitored by the first pressure gauge is higher than the internal pressure of the sample kettle. In this step, the internal pressure of the sample kettle is the pressure value monitored by the second pressure gauge after the exhaustion production test in step S400, so as to realize the simulation test of CO2 "injection". After the CO2 injection is balanced, close the outlet of the second high-pressure gas source of the three-way valve, close the first stop valve, and read the balanced internal pressure of the reference kettle through the first pressure gauge. At this time, the fluid pressure in the reference kettle is the injection pressure of CO2. By changing the fluid pressure in the reference kettle through the fluid injection system, the influence of the CO2 injection pressure on the CO2 throughput and enhanced recovery and storage effect can be explored; Step S530: After the CO2 injection is completed, the first stop valve is closed and the second stop valve is opened. Since the internal pressure of the reference kettle is higher than that of the sample kettle, CO2 enters the sample kettle from the reference kettle under the action of the pressure difference until it is fully balanced, thus realizing the simulation test of CO2 "swallowing"; Step S540: close the second stop valve and leave the nuclear magnetic resonance analysis test system still for 6 hours to allow the CO2 to fully diffuse and transfer in the shale medium, thus realizing a simulation test of CO2 "stewing"; Step S550: After the CO2 "stewing" process is balanced, the pressure in the sample kettle after balance is read through the first pressure gauge. In this process, the influence of the stewing time on the CO2 throughput to enhance the recovery rate and the sealing effect can be explored by controlling the standing time. Finally, the third stop valve is opened, and the back pressure valve and the third plunger pump cooperate to control the outlet pressure to be lower than the pressure in the sample kettle, so that the fluid in the sample kettle is output to the recovery kettle, realizing the simulation test of CO2 "exhalation".

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