Method for simulating full-life-cycle gas-water occurrence and utilization of low-permeability tight gas reservoir

Abstract

The embodiment of the invention provides a method for simulating full-life-cycle gas-water occurrence and utilization of a low-permeability tight gas reservoir, and belongs to the technical field of gas reservoir development. The method comprises the following steps: constructing an online nuclear magnetic core displacement experimental device; debugging test parameters of the online nuclear magnetic core displacement experiment device; according to the online nuclear magnetic core displacement experimental device, gas-water occurrence and dynamic changes of a reservoir forming stage, a depletion exploitation stage and a gas injection recovery efficiency improving stage are continuously simulated for a core. According to the method, the gas-water occurrence and dynamic change characteristics in the full life cycle process of low-permeability tight gas reservoir filling reservoir forming-depletion exploitation-gas injection recovery efficiency improvement can be accurately described from the microscopic angle, and technical support is provided for deployment and adjustment of a gas reservoir development scheme and optimization of technical measures for gas injection recovery efficiency improvement in the later development period.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas reservoir development, in particular to a method for simulating gas-water occurrence and movement in the whole life cycle of a low-permeability tight gas reservoir. BACKGROUND

[0002] Unlike conventional gas reservoirs, low-permeability tight sandstone gas reservoirs have the characteristics of poor reservoir properties, strong heterogeneity and complex gas-water relationship, which makes natural gas exploration and development face a series of technical problems. Among them, it is of great significance to clarify the occurrence state of gas and water in the reservoir and its percolation characteristics for effective use of natural gas resources in the tight matrix and thus to improve the recovery efficiency of the gas reservoir. The percolation capacity of gas and water in the tight reservoir is significantly different, and water locking effect is easily caused in the process of depletion production in low-permeability tight sandstone gas reservoirs, which seriously affects the gas well production. Therefore, in-depth study of the occurrence state of gas and water in low-permeability tight sandstone gas reservoirs at the microscale and its flow mechanism in the tight reservoir is of great significance for the deployment of gas reservoir development plan, adjustment and optimization of post-enhanced recovery technology measures.

[0003] At present, in the field of oil exploration and development, nuclear magnetic resonance (NMR) technology, as an advanced non-destructive rock physical analysis method, provides a new way for the study of low-permeability tight sandstone gas reservoirs due to its unique advantages. NMR technology can directly or indirectly obtain key parameters such as porosity, permeability, pore size distribution and fluid saturation of reservoir rocks by measuring the relaxation signal of hydrogen nuclei under the action of an external magnetic field. These parameters have important value for understanding the physical properties of gas reservoirs and evaluating their exploration potential. Specifically, NMR technology can realize rapid, fine and non-destructive measurement of rock samples. By comparing the NMR response of rock samples under different water saturation or different gas pressure conditions, researchers can deeply understand the micro-distribution of gas and water in the reservoir and their interaction mechanism. In addition, NMR technology can also provide detailed information about pore structure, fluid type and fluid distribution, which has important guiding role for optimizing the development plan of gas reservoirs and improving recovery efficiency.

[0004] In summary, the use of NMR technology to study low-permeability tight sandstone gas reservoirs helps to clarify the occurrence state and movement characteristics of gas and water at the microscale, and provides strong technical support and theoretical basis for the development of gas reservoirs. Therefore, in the oil industry, the application of NMR technology is becoming more and more widespread.

[0005] The paper "Research on the migration characteristics of tight sandstone gas based on NMR technology", Fang Tao et al. (Fang Tao, Zhang Li-kuan, Zhang Li-qiang, et al. Research on the migration characteristics of tight sandstone gas based on NMR technology[J]. Journal of Gansu Sciences, 2017, 29(4): 22-27.) established a set of gas displacement experimental device and method based on NMR online detection with artificial core and natural tight core as materials, which was used to study the gas water filling and migration characteristics of tight sandstone gas reservoir.

[0006] The Chinese patent "Method for characterizing different types of fluid distribution in tight sandstone based on NMR", with authorization announcement number CN114778588A, discloses a method for characterizing different types of fluid distribution in tight sandstone based on NMR. By comparing the changes of T2 spectrum in saturated oil state, centrifugal state and spontaneous imbibition, the content and micro-distribution of different types of fluid in the original state of tight sandstone reservoir are determined, which provides support for understanding the flow mechanism of tight sandstone and predicting the production of tight oil.

[0007] The Chinese patent "Method for evaluating the charging process of tight oil by using NMR-displacement combined device", with authorization announcement number CN108414560B, discloses a method for evaluating the charging process of tight oil by using NMR-displacement combined device. The NMR device is operatively connected with the core holder device to complete the online monitoring of the displacement process of tight sandstone by using NMR technology. The method uses fluorine oil to displace the saturated formation water core without hydrogen signal, and combines with the geological conditions to comprehensively evaluate the charging process in the formation.

[0008] The Chinese patent "Method for testing the mobility of reservoir pore water", with authorization announcement number CN104316554A, discloses a method for testing the mobility of reservoir pore water. The method measures the T2 spectrum of saturated water core, the T2 spectrum of core under initial water content state and the T2 spectrum in the process of water displacement by gradually increasing pressure gas, and uses the established predetermined algorithm to obtain the mobility of reservoir pore water, and clearly determines the gas water occurrence ratio and state in the charging process of gas reservoir.

[0009] The Chinese patent "Classification and evaluation method for the mobility of tight sandstone reservoir pores", with authorization announcement number CN110687153B, discloses a classification and evaluation method for the mobility of tight sandstone reservoir pores. The method obtains the saturation water NMR curve, bound water NMR curve, mercury injection saturation and mercury injection pressure by performing NMR and high pressure mercury injection test on the sample. According to the mercury injection saturation and mercury injection pressure data, the intergranular pores and intragranular pores are divided. According to the saturation water NMR curve and the bound water NMR curve, combined with the boundary of intergranular pores and intragranular pores, the movable pores and immovable pores are divided, and the content of different types of pores is calculated.

[0010] The present inventors find in the process of implementing the present application that the above-mentioned scheme of the prior art has the following defects: on the one hand, the researches applying the nuclear magnetic resonance technology mainly focus on the gas-water filling in the accumulation stage, the multiphase percolation mechanism and the original occurrence state, and lack of a systematic and comprehensive method to simulate the whole life cycle process of the low-permeability tight gas reservoir, including the key stages of accumulation, depletion production and gas injection enhanced recovery; on the other hand, the off-line detection is used for the nuclear magnetic resonance T2 spectrum detection of the core in different states, which cannot eliminate the influences of the temperature change, the pressure change and the fluid expansion in the core on the test results, and cannot simulate the real reservoir temperature and pressure conditions. These limitations make the researchers face challenges in understanding and predicting the gas-water occurrence and dynamic change characteristics of the low-permeability tight gas reservoir. SUMMARY

[0011] The purpose of the embodiments of the present application is to provide a method which can accurately simulate the gas-water occurrence and production process in the whole life cycle of the low-permeability tight sandstone gas reservoir from the micro scale. Through this method, the original occurrence state of the gas and water in different pores of the low-permeability tight sandstone gas reservoir and the dynamic change thereof in the development process can be determined, and the gas-water micro occurrence and dynamic change characteristics of the low-permeability tight gas reservoir can be accurately described, thereby providing a scientific basis for the deployment and adjustment of the gas reservoir development scheme, and providing technical support for the selection and optimization of the gas injection enhanced recovery technical measures in the later development stage.

[0012] In order to achieve the above-mentioned purpose, the embodiments of the present application provide a method for simulating the gas-water occurrence and production in the whole life cycle of a low-permeability tight gas reservoir, which comprises the following steps: building an online nuclear magnetic core displacement experiment device; debugging the test parameters of the online nuclear magnetic core displacement experiment device; simulating the gas-water filling process in the accumulation stage of the core according to the online nuclear magnetic core displacement experiment device, and obtaining a plurality of T2 spectrum curves in the accumulation stage; after the simulation of the gas-water filling process in the accumulation stage is completed, displacing the natural gas into the core at a constant pressure, and aging for a preset time after the pressure is stable; continuing to simulate the depletion production stage according to the online nuclear magnetic core displacement experiment device after the preset aging time, and obtaining a plurality of T2 spectrum curves in the depletion production stage; and continuing to simulate the gas injection enhanced recovery stage according to the online nuclear magnetic core displacement experiment device after the simulation of the depletion production stage is completed, and obtaining a plurality of T2 spectrum curves in the gas injection enhanced recovery stage.

[0013] Optionally, the online NMR core displacement experiment device comprises a power system, a test system, a metering system and an NMR signal analysis system, wherein the power system comprises a displacement pump, a first intermediate container and a second intermediate container, the first intermediate container is filled with natural gas, the second intermediate container is filled with a displacement agent, the displacement pump is used to displace the natural gas or the displacement agent in the intermediate container, and the first intermediate container and the second intermediate container are both provided with upper and lower valves; the test system comprises a non-magnetic core holder, a confining pressure pump, a magnet, a back pressure valve and a back pressure pump, a probe and core holder inlet and outlet valves, the non-magnetic core holder is used to fix a core, the confining pressure pump is used to apply confining pressure to the core, the magnet is used to magnetize the protons of the fluid in the core, the probe is used to excite and receive the NMR signal of the core, and the back pressure valve and the back pressure pump are used to control the pressure at the outlet of the core holder; the metering system comprises a first measuring cylinder and a drainage gas recovery device, the first measuring cylinder is used to collect and meter the amount of produced liquid, and the drainage gas recovery device comprises a second measuring cylinder and a water tank, which are used to collect and meter the volume of produced gas; and the NMR signal analysis system comprises a computer and an NMR spectrometer, the NMR spectrometer is used to control and emit a radio frequency pulse signal to excite the core to generate an NMR signal, and to control and receive the NMR signal generated by the core, and the computer is used to control the NMR spectrometer to excite and receive the NMR signal of the core and to inverse the collected echo train to obtain a T2 spectrum curve.

[0014] Optionally, the test parameters of the online NMR core displacement experiment device are debugged by debugging system parameters of the NMR signal analysis system, wherein the system parameters comprise echo time interval, waiting time, echo number, scanning number and experiment temperature.

[0015] Optionally, the method further comprises: determining a conversion coefficient C of relaxation time T2 and pore size r according to a dry core; and converting the relaxation time T2 on the coordinate axis in the plurality of T2 spectrum curves to the pore size r according to the conversion coefficient C, wherein the determination of the conversion coefficient C of relaxation time T2 and pore size r according to the dry core comprises: taking part of the dry core; performing a mercury injection experiment on the dry core to determine a pore size distribution curve of the dry core; taking another part of the dry core, and determining a T2 spectrum curve after the dry core is pressurized and saturated with simulated formation water; determining a NMR-mercury injection pore size distribution comparison curve according to the pore size distribution curve and the T2 spectrum curve; and determining the conversion coefficient C of relaxation time T2 and pore size r through the formula T2 = Cr according to the NMR-mercury injection pore size distribution comparison curve.

[0016] Optionally, the pressurized saturation of the dry core with simulated formation water comprises: cleaning and drying the dry core; placing the dried core in a vacuumizing device, and vacuumizing the core by using a turbo molecular pump; closing the turbo molecular pump valve, opening an intermediate container containing simulated formation water, and self-sucking the simulated formation water into the vacuumizing device; and opening a displacement pump valve, setting a constant pressure displacement of the simulated formation water in the intermediate container into the vacuumizing device at a pre-set pressure for a pre-set time.

[0017] Optionally, the simulation of the gas-water filling process in the reservoir-forming stage of the core according to the online nuclear magnetic core displacement experiment device and the obtaining of a plurality of T2 spectrum curves in the reservoir-forming stage comprises: placing the core saturated with simulated formation water into the non-magnetic core holder, setting the back pressure pump pressure, opening the core holder inlet valve, the core holder outlet valve, and the upper and lower valves of the first intermediate container, and simulating the gas-water filling process in the reservoir-forming stage by using a step-by-step pressurization gas displacement method; and when uniform gas production occurs in the water drainage and gas production device, a plurality of T2 spectrum curves after the gas-water filling in the reservoir-forming stage at different pressure gradients are respectively measured by the nuclear magnetic resonance signal analysis system.

[0018] Optionally, the constant pressure displacement of natural gas into the core, and the aging for a pre-set time after the pressure is stable comprises: after the simulation of the gas-water filling process in the reservoir-forming stage is completed, closing the core holder outlet valve, setting the displacement pump pressure to be the original formation pressure of the target block, and constant pressure displacement of the natural gas in the first intermediate container into the core; after the pressure is stable for 2 hours, closing the core holder inlet valve and the upper and lower valves of the first intermediate container, and aging for a pre-set time.

[0019] Optionally, the continuing simulation of the depletion production stage and the obtaining of a plurality of T2 spectrum curves in the depletion production stage comprises: after the pre-set aging time, setting the back pressure pump pressure, opening the core holder outlet valve, and simulating the depletion production by using a gradient pressure reduction method; when no gas is produced in the water drainage and gas production device, a plurality of T2 spectrum curves after the depletion production simulation at different gradient back pressures are respectively measured by the nuclear magnetic resonance signal analysis system; and when the depletion production reaches a pre-set abandonment pressure, the depletion production simulation is stopped.

[0020] Optionally, the continuing simulation of the gas injection enhanced recovery stage and obtaining a plurality of T2 spectrum curves of the gas injection enhanced recovery stage comprises: after the depletion production to a preset abandonment pressure, opening the core holder inlet end valve and the upper and lower valves of the second intermediate container, presetting a plurality of injection pressures of the displacement pumps, and injecting the displacement agent in the second intermediate container at a constant pressure; when the gas is uniformly produced in the drainage gas production device, a plurality of T2 spectrum curves after the gas injection enhanced recovery simulation at different injection pressures are measured by the nuclear magnetic resonance signal analysis system.

[0021] Optionally, the displacement agent is injection gas, and the injection gas is one of N2 or CO2 or air.

[0022] Through the above technical solution, the pre-prepared target block core to be detected, simulated formation water, natural gas and displacement agent are used, the online nuclear magnetic core displacement experiment device is debugged, the simulation of the original gas water filling and micro occurrence state in the reservoir forming stage, the micro occurrence and production characteristics of gas and water in the depletion production stage and the micro occurrence and production characteristics of gas and water in the gas injection enhanced recovery stage are connected, and a plurality of T2 spectrum curves of the reservoir forming stage, the depletion production stage and the gas injection enhanced recovery stage are measured by the nuclear magnetic resonance signal analysis system in the online nuclear magnetic core displacement experiment device, wherein the relaxation time T2 of the horizontal axis of the T2 spectrum curve is converted into the pore diameter r through the conversion coefficient C determined by the application, and then the application can simulate the gas water occurrence and dynamic change process of the whole life cycle of the low-permeability tight gas reservoir from the micro scale, can clearly determine the gas water distribution and dynamic change characteristics in different pores, can more accurately describe the gas water micro occurrence characteristics of the low-permeability tight gas reservoir, can provide a scientific basis for the deployment and adjustment of the gas reservoir development plan, and can provide technical support for the selection and optimization of the gas injection enhanced recovery technical measures in the later development stage.

[0023] Other features and advantages of the embodiments of the application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are included to provide a further understanding of the embodiments of the application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the application, but do not constitute a limitation on the embodiments of the application. In the drawings:

[0025] Figure 1 is a method flow chart for simulating the gas water occurrence and production of the whole life cycle of the low-permeability tight gas reservoir provided by the embodiments of the application.

[0026] Figure 2 is a nuclear magnetic-mercury injection pore size distribution comparison curve diagram provided by the embodiments of the application.

[0027] Figure 3is a schematic diagram of an online nuclear magnetic core displacement experiment device provided by an embodiment of the present application.

[0028] Figure 4 is a process schematic diagram of an online nuclear magnetic core displacement experiment device provided by an embodiment of the present application.

[0029] Figure 5 is a T2 spectrum curve change graph of a reservoir forming stage provided by an embodiment of the present application.

[0030] Figure 6 is a T2 spectrum curve change graph of a depletion production stage provided by an embodiment of the present application.

[0031] Figure 7 is a T2 spectrum curve change graph of a CO2 injection enhanced recovery stage provided by an embodiment of the present application.

[0032] Legend of reference signs

[0033] 1 confining pressure pump 2 displacement pump

[0034] 3 first intermediate container 4 second valve

[0035] 5 second intermediate container 6 core holder inlet end valve

[0036] 7 magnet 8 probe

[0037] 9 nuclear magnetic resonance spectrometer 10 computer

[0038] 11 second measuring cylinder 12 first valve

[0039] 13 third valve 14 non-magnetic core holder

[0040] 15 core holder outlet end valve 16 back pressure valve

[0041] 17 back pressure pump 18 first measuring cylinder

[0042] 19 water tank DETAILED DESCRIPTION

[0043] The specific embodiments of the embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application.

[0044] Figure 1 is a process flow chart of a method for simulating gas and water occurrence and movement in a full life cycle of a low-permeability tight gas reservoir provided by an embodiment of the present application, as shown in Figure 1 The method for simulating gas and water occurrence and movement in a full life cycle of a low-permeability tight gas reservoir includes:

[0045] Step S10, an online nuclear magnetic core displacement experiment device is built.

[0046] In some embodiments, Figure 3 is a schematic diagram of an online nuclear magnetic core displacement experiment device provided by the embodiments of the present application, Figure 4 is a process schematic diagram of an online nuclear magnetic core displacement experiment device provided by the embodiments of the present application, and Figure 3 and Figure 4 As shown in the drawings, the online nuclear magnetic core displacement experiment device comprises a power system, a test system, a metering system and a nuclear magnetic resonance signal analysis system, wherein the power system comprises a displacement pump 2, a first intermediate container 3 and a second intermediate container 5, the first intermediate container 3 is filled with natural gas, the second intermediate container 5 is filled with a displacement agent, and the displacement pump 2 is used to displace the natural gas or the displacement agent in the intermediate containers. Optionally, the upper and lower ends of any intermediate container are provided with upper and lower valves for controlling whether the substance filled in the intermediate container is output from the intermediate container. In the embodiments of the present application, the upper and lower valves of the first intermediate container 3 are preferably a second valve 4 and a first valve 12, respectively. In the embodiments of the present application, the upper valve of the second intermediate container 5 and the core holder inlet end valve 6 are preferably the same valve, i.e. the upper and lower valves of the second intermediate container 5 are preferably the core holder inlet end valve 6 and a third valve 13, respectively. In the embodiments of the present application, the displacement pump 2 is preferably a high-precision ISCO displacement pump. Specifically, the test system comprises a non-magnetic core holder 14, a confining pressure pump 1, a magnet 7, a back pressure valve 16 and a back pressure pump 17, a probe 8, and a core holder inlet end valve 6 and a core holder outlet end valve 15. The non-magnetic core holder 14 is used to fix a core, the confining pressure pump 1 is used to apply confining pressure to the core, the magnet 7 is used to magnetize the protons of the fluid in the core, the probe 8 is used to excite and receive the nuclear magnetic resonance signal of the core, and the back pressure valve 16 and the back pressure pump 17 are used to control the pressure at the outlet end of the core holder. Optionally, the confining pressure pump 1 applies confining pressure to the core by using a confining pressure medium. In the embodiments of the present application, the confining pressure medium is preferably fluorine oil containing no H + signal, and the confining pressure pump 1 is preferably a high-precision ISCO confining pressure pump. The magnet 7 is preferably a low-field permanent magnet. As shown in the drawings, Figure 3As shown, the core holder inlet end valve 6 is installed between the upper end of the second intermediate container 5 and the inlet end of the non-magnetic core holder 14, and the core holder outlet end valve 15 is installed at the outlet end of the non-magnetic core holder 14. Specifically, the metering system includes a first measuring cylinder 18 for collecting and metering the amount of produced liquid, and a drainage gas recovery device including a second measuring cylinder 11 and a water tank 19 for collecting and metering the volume of produced gas. Specifically, the nuclear magnetic resonance signal analysis system includes a computer 10 and a nuclear magnetic resonance spectrometer 9, wherein the nuclear magnetic resonance spectrometer 9 is used to control and emit radio frequency pulse signals to excite the core to generate nuclear magnetic resonance signals, and to control and receive the nuclear magnetic resonance signals generated by the core, and the computer 10 is used to control the nuclear magnetic resonance spectrometer 9 to excite and receive the nuclear magnetic resonance signals of the core, and to perform inversion on the collected echo train to obtain a T2 spectrum curve.

[0047] Step S20, debugging the test parameters of the online nuclear magnetic core displacement experiment device;

[0048] In some embodiments, the debugging of the test parameters of the online nuclear magnetic core displacement experiment device includes debugging of system parameters of the nuclear magnetic resonance signal analysis system, wherein the system parameters include echo time interval, waiting time, echo number, scan number and experimental temperature. Optionally, the present embodiment preferably uses CPMC sequence, sets the echo time interval to 0.5 ms, the waiting time to 10000 ms, the echo number to 18000, the scan number to 64 times, and the experimental temperature to 35℃.

[0049] Step S30, simulating the gas-water filling process of the reservoir formation stage by the online nuclear magnetic core displacement experiment device, and obtaining a plurality of T2 spectrum curves of the reservoir formation stage;

[0050] In some embodiments, the gas-water filling process of the core simulation reservoir forming stage and obtaining a plurality of T2 spectrum curves of the reservoir forming stage include: loading the core saturated with simulated formation water into the non-magnetic core holder 14, setting the back pressure pump 17 pressure, opening the core holder inlet end valve 6, core holder outlet end valve 15 and the upper and lower valves of the first intermediate container 3, and simulating the gas-water filling process of the reservoir forming stage by using the step-by-step pressurized gas drive method; and by the nuclear magnetic resonance signal analysis system, when the gas is uniformly produced in the drainage gas recovery device, a plurality of T2 spectrum curves after the gas-water filling at the initial and different pressure gradients in the reservoir forming stage are measured respectively. Specifically, first, the dry core saturated with the simulated formation water is loaded into the non-magnetic core holder 14 after the dry core is obtained by core processing of the target block, and the first T2 spectrum curve of the initial reservoir forming stage is measured, wherein the dry core is obtained by drilling the columnar core of the target block and cleaning and drying the core, and the simulated formation water can be prepared in the laboratory according to the ion composition of the formation water of the target block or directly taken from the formation water of the target block. Then, by setting different pressure gradients of the back pressure pump 17, opening the second valve 4 and the first valve 12 of the upper and lower ends of the first intermediate container 3, and opening the core holder inlet end valve 6 and the core holder outlet end valve 15, the gas-water filling process of the reservoir forming stage is simulated by using the step-by-step pressurized gas drive method, and when the gas bubbles are uniformly produced in the drainage gas recovery device, a plurality of T2 spectrum curves under different pressure gradients of the back pressure pump 17 are measured. Optionally, the different pressure gradients can be set according to the actual pressure gradient of the gas reservoir, and the pressure gradient is preferably 0.1 MPa / cm and 0.4 MPa / cm. Specifically, the back pressure pump 17 performs the gas-water filling process simulation experiment of the reservoir forming stage at a pressure gradient of 0.1 MPa / cm, and when the gas bubbles are uniformly produced in the drainage gas recovery device, the second T2 spectrum curve of the reservoir forming stage is measured. Then, the back pressure pump 17 performs the gas-water filling process simulation experiment of the reservoir forming stage at a pressure gradient of 0.4 MPa / cm, and when the gas bubbles are uniformly produced in the drainage gas recovery device, the third T2 spectrum curve of the reservoir forming stage is measured.

[0051] In some embodiments, the plurality of T2 spectrum curves after the gas-water filling process simulation experiment of the reservoir forming stage at different pressure gradients refer to the reservoir forming stage T2 spectrum curve change diagram shown in Figure 5 Figure 5 ​As shown, optionally, the method for simulating the entire life cycle gas-water occurrence and utilization of a low-permeability tight gas reservoir further includes: determining the conversion coefficient C between relaxation time T2 and pore size r based on the dry core; and converting the relaxation time T2 of the coordinate axes in the multiple T2 spectrum curves into pore size r based on the conversion coefficient C. Optionally, determining the conversion coefficient C between relaxation time T2 and pore size r based on the dry core includes: taking a portion of the dry core; performing mercury intrusion porosimetry on the dry core to determine the pore size distribution curve; taking another portion of the dry core, pressurizing and saturating it with simulated formation water, and determining the T2 spectrum curve; determining a nuclear magnetic resonance (NMR)-mercury intrusion porosimetry (MIP) pore size distribution comparison curve based on the pore size distribution curve and the T2 spectrum curve; and determining the conversion coefficient C between relaxation time T2 and pore size r based on the NMR-MIP pore size distribution comparison curve using the formula: T2 = Cr. In the formula T2 = Cr, the relaxation time T2 is in milliseconds (ms), the pore size r is in micrometers (μm), and the conversion coefficient C is dimensionless. Specifically, the NMR-mercury intrusion porosimetry pore size distribution comparison curve is shown below. Figure 2 As shown, Figure 2 The curve with the square black blocks shown is the pore size distribution curve determined by mercury intrusion porosimetry (MIP) according to an embodiment of the present invention. Figure 2 The curve shown is the T2 spectrum curve determined by an nuclear magnetic resonance spectrometer according to an embodiment of the present invention. (See attached image.) Figure 2 As shown, according to the formula: T2 = Cr, the conversion coefficient C between the relaxation time T2 and the aperture r provided in this embodiment of the invention is determined to be 40.

[0052] In some embodiments, pressurizing and saturating a dry core with simulated formation water includes: core cleaning and drying; placing the dried core in a vacuum pumping device and using a turbomolecular pump to evacuate the core; closing the turbomolecular pump valve, opening the intermediate container holding the simulated formation water, and allowing the simulated formation water to be drawn into the vacuum pumping device; opening the displacement pump valve, setting the pressure to a preset constant pressure to displace the simulated formation water in the intermediate container into the vacuum pumping device, and pressurizing and saturating for a preset time. Optionally, in this embodiment of the invention, a turbomolecular pump is preferably used to evacuate the core to 10... -5 mbar; the preset constant pressure is 20MPa, and the preset time for pressurization saturation is 48h.

[0053] For details, please refer to Figure 5 As shown, the horizontal axis of the T2 spectrum curve represents the aperture r after conversion based on the conversion factor C with a value of 40. Optionally, in this embodiment of the invention, the aperture r is set to... Figure 5 The first trough in the diagram serves as the boundary; the pore size to the left of the first trough is considered small, and the pore size to the right of the first trough is considered large. (See also...)Figure 5 As shown in the figure, water in the large pores is easy to be driven, and the proportion of water in the large pores being displaced is greater than that in the small pores, and the bound water is mainly distributed in the small pores.

[0054] Step S40, after the simulation of the gas-water filling process of the accumulation stage is completed, constant pressure displacement of natural gas into the core is performed, and after the pressure is stabilized, the core is aged for a preset time;

[0055] In some embodiments, the constant pressure displacement of natural gas into the core, after the pressure is stabilized, and the aging for a preset time includes: after the simulation of the gas-water filling process of the accumulation stage is completed, the outlet end valve 15 of the core holder is closed, the pressure of the displacement pump 2 is set to the original formation pressure of the target block, the natural gas in the first intermediate container 3 is constantly pressure-displaced into the core, after the pressure is stabilized for 2 hours, the inlet end valve 6 of the core holder and the upper and lower valves of the first intermediate container 3 are closed, and the core is aged for a preset time. Optionally, the original formation pressure of the embodiment of the present application is preferably 20 MPa, and the preset time is preferably 24 h. Specifically, the displacement pump 2 is set to displace the natural gas in the first intermediate container 3 into the non-magnetic core holder 14 at a pressure of 20 MPa, after the pressure value on the panel of the displacement pump 2 is stabilized at 20 MPa for 2 hours, the inlet end valve 6 of the core holder and the upper and lower valves (the second valve 4 and the first valve 12) of the first intermediate container 3 are closed, and the core is aged for 24 h.

[0056] Step S50, after the preset aging time, according to the online nuclear magnetic core displacement experiment device, the depletion production stage is continuously simulated, and a plurality of T2 spectrum curves of the depletion production stage are obtained;

[0057] In some embodiments, after the aging preset time, the back pressure pump 17 pressure is set, the core holder outlet end valve 15 is opened, and the depletion simulation is carried out in a stepwise pressure reduction manner; when there is no gas production in the drainage gas production device, the nuclear magnetic resonance signal analysis system is used to measure a plurality of T2 spectrum curves after the depletion simulation at different gradient back pressures; and when the depletion simulation reaches a preset abandonment pressure, the depletion simulation is stopped. Optionally, after the aging preset time and before the back pressure pump 17 pressure is set, the nuclear magnetic resonance signal analysis system is used to measure the original formation pressure T2 spectrum curve at the original formation pressure of 20 MPa in the depletion stage. The T2 spectrum curve at the original formation pressure of 20 MPa in the depletion stage can also be the third T2 spectrum curve in the accumulation stage. Optionally, the back pressure of the back pressure valve 16 can be arranged with 3-5 pressure points according to the difference between the original formation pressure and the abandonment pressure of the gas reservoir. In the embodiments of the present application, the original formation pressure is preferably 20 MPa, the abandonment pressure is preferably 9 MPa, and the back pressure pump 17 pressure is preferably 17 MPa, 13 MPa and 9 MPa, i.e. depletion of 3 MPa, depletion of 7 MPa and depletion of 11 MPa.

[0058] Specifically, the back pressure pump 17 is used to set the back pressure to 17 MPa, and when there is no gas production in the drainage gas production device, the first T2 spectrum curve in the depletion stage is measured; the back pressure pump 17 is used to set the back pressure to 13 MPa, and when there is no gas production in the drainage gas production device, the second T2 spectrum curve in the depletion stage is measured; the back pressure pump 17 is used to set the back pressure to 9 MPa, and when there is no gas production in the drainage gas production device, the third T2 spectrum curve in the depletion stage is measured; after the third T2 spectrum curve in the depletion stage is measured, the second valve 4 and the first valve 12 at the upper and lower ends of the first intermediate container 3 are closed, the output of natural gas in the first intermediate container 3 is stopped, and the depletion simulation experiment is stopped. The plurality of T2 spectrum curves after the depletion stage simulation experiment in a stepwise pressure reduction manner can be seen from the T2 spectrum curve change diagram of the depletion stage shown in Figure 6 Figure 6 It can be seen from the T2 spectrum curve change diagram of the depletion stage shown in Figure 6 The first wave trough in the T2 spectrum curve is set as a boundary, and the pore size corresponding to the left side of the first wave trough is a small pore, and the pore size corresponding to the right side of the first wave trough is a large pore. Referring to Figure 6 In the depletion stage, the water content in the small pores decreases, which is manifested as a decrease in the left peak; the water content in the large pores is basically unchanged, and after the depletion, the water content in the large pores even increases, which is due to the migration of water in the small pores to the large pores.​

[0059] Step S60, after the simulation of the depletion production stage is completed, according to the online nuclear magnetic core displacement experiment device, a gas injection enhanced recovery stage is continued to be simulated, and a plurality of T2 spectrum curves of the gas injection enhanced recovery stage are obtained.

[0060] In some embodiments, the continuing to simulate the gas injection enhanced recovery stage and obtaining the plurality of T2 spectrum curves of the gas injection enhanced recovery stage comprises: after the depletion production to a preset abandonment pressure, opening the core holder inlet end valve 6 and the upper and lower valves of the second intermediate container 5, presetting a plurality of injection pressures of the displacement pumps 2, and injecting the displacement agent in the second intermediate container 5 at a constant pressure; through the nuclear magnetic resonance signal analysis system, when the gas is uniformly produced in the drainage gas production device, a plurality of T2 spectrum curves after the gas injection enhanced recovery simulation at different injection pressures are respectively determined. Optionally, in the embodiment of the present application, the abandonment pressure is preferably 9 MPa, the plurality of injection pressures of the displacement pumps 2 can be selected as 10 MPa, 13 MPa, 16 MPa and 19 MPa, the constant pressure injection can be selected as pulse injection, the displacement agent in the second intermediate container 5 is injection gas, and the injection gas can be selected as one of N2 or CO2 or air. In the embodiment of the present application, the displacement agent in the second intermediate container 5 is CO2. Specifically, after the depletion production to 9 MPa, the core holder outlet end valve 15 is kept in an open state, the core holder inlet end valve 6 and the third valve 13 of the upper and lower ends of the second intermediate container 5 are opened, the injection pressure of the displacement pump 2 is set to 10 MPa, the CO2 displacement agent is injected at a constant pressure, the volume of the produced gas is measured by the metering system, when the gas bubbles are stably produced in the drainage gas production device, the first T2 spectrum curve of the gas injection enhanced recovery stage is determined by the nuclear magnetic resonance signal analysis system; the injection pressure of the displacement pump 2 is set to 13 MPa, the CO2 displacement agent is injected at a constant pressure, the volume of the produced gas is measured by the metering system, when the gas bubbles are stably produced in the drainage gas production device, the second T2 spectrum curve of the gas injection enhanced recovery stage is determined; the injection pressure of the displacement pump 2 is set to 16 MPa, the CO2 displacement agent is injected at a constant pressure, the volume of the produced gas is measured by the metering system, when the gas bubbles are stably produced in the drainage gas production device, the third T2 spectrum curve of the gas injection enhanced recovery stage is determined; the injection pressure of the displacement pump 2 is set to 19 MPa, the CO2 displacement agent is injected at a constant pressure, the volume of the produced gas is measured by the metering system, when the gas bubbles are stably produced in the drainage gas production device, the fourth T2 spectrum curve of the gas injection enhanced recovery stage is determined; when the T2 spectrum curve is stable and does not change, the T2 spectrum curve test is stopped. The plurality of T2 spectrum curves after the simulation experiment of the gas injection enhanced recovery stage at different injection pressures are shown in FIG. 6. Figure 7The diagram shown depicts the T2 spectrum changes during the CO2 injection enhanced oil recovery stage. Figure 7 As can be seen from the graph, the horizontal axis of the T2 spectrum curve represents the aperture r after conversion based on the conversion coefficient C with a value of 10. Optionally, in this embodiment of the invention, the aperture r is set to be... Figure 7 The first trough in the diagram serves as the boundary; the pore size to the left of the first trough is considered small, and the pore size to the right of the first trough is considered large. (See also...) Figure 7 As shown, many T2 spectrum curves remained largely unchanged, indicating that the bound water was not utilized during this stage.

[0061] This invention provides a storage medium storing a program that, when executed by a processor, implements the method for simulating the gas-water accumulation and utilization throughout the entire life cycle of a low-permeability tight gas reservoir.

[0062] This invention provides a processor for running a program, wherein the program executes the method for simulating the gas-water accumulation and utilization throughout the entire life cycle of a low-permeability tight gas reservoir.

[0063] This invention provides a device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps: 1. Constructing an online nuclear magnetic resonance (NMR) core displacement experimental device; 2. Adjusting the test parameters of the online NMR core displacement experimental device; 3. Simulating the gas-water injection process of the reservoir formation stage using the online NMR core displacement experimental device, and obtaining multiple T2 spectrum curves for the reservoir formation stage, wherein the dry core is obtained after core processing of the target block; 4. After the simulation of the gas-water injection process of the reservoir formation stage is completed, displacing natural gas into the core at constant pressure, and aging for a preset time after the pressure stabilizes; 5. After the preset aging time, continuing to simulate the depletion extraction stage using the online NMR core displacement experimental device, and obtaining multiple T2 spectrum curves for the depletion extraction stage; 6. After the simulation of the depletion extraction stage is completed, continuing to simulate the gas injection enhanced oil recovery stage using the online NMR core displacement experimental device, and obtaining multiple T2 spectrum curves for the gas injection enhanced oil recovery stage.

[0064] Optionally, the online NMR core displacement experiment device comprises: a power system comprising a displacement pump, a first intermediate container and a second intermediate container, wherein the first intermediate container is filled with natural gas, the second intermediate container is filled with a displacement agent, the displacement pump is used to displace the natural gas or the displacement agent in the intermediate container, and the first intermediate container and the second intermediate container are both provided with upper and lower valves at upper and lower ends; a test system comprising a non-magnetic core holder, a confining pressure pump, a magnet, a back pressure valve and a back pressure pump, a probe and core holder inlet and outlet valves, wherein the non-magnetic core holder is used to fix a core, the confining pressure pump is used to apply confining pressure to the core, the magnet is used to polarize hydrogen nuclei of a fluid in the core, the probe is used to capture relaxation signal T2 of the hydrogen nuclei of the fluid, and the back pressure valve and the back pressure pump are used to control pressure at the core holder outlet; a metering system comprising a first measuring cylinder and a drainage gas production device, wherein the first measuring cylinder is used to collect and meter the amount of produced liquid, and the drainage gas production device comprises a second measuring cylinder and a water tank, and is used to collect and meter the volume of produced gas; and an NMR signal analysis system comprising a computer and an NMR spectrometer, wherein the NMR spectrometer is used to collect the relaxation signal T2 captured by the probe, and the computer is used to inverse the collected echo train to obtain a T2 spectrum curve.

[0065] Optionally, the test parameters of the online NMR core displacement experiment device are debugged, which comprises debugging system parameters of the NMR signal analysis system, wherein the system parameters comprise echo time interval, waiting time, echo number, scanning number and experimental temperature.

[0066] Optionally, the gas-water charging process in the reservoir-forming stage is simulated for the dry core according to the online NMR core displacement experiment device, and a plurality of T2 spectrum curves in the reservoir-forming stage are obtained, which comprises: after the dry core is pressurized to simulate water saturation of the formation, the core is loaded into the non-magnetic core holder, the back pressure pump pressure is set, the core holder inlet and outlet valves and the upper and lower valves of the first intermediate container are opened, and the step-by-step pressurized gas drive method is adopted to simulate the gas-water charging process in the reservoir-forming stage; and the plurality of T2 spectrum curves after the gas-water charging in the initial and different pressure gradients in the reservoir-forming stage are respectively measured by the NMR signal analysis system when uniform gas production occurs in the drainage gas production device.

[0067] Optionally, the natural gas in the first intermediate container is constantly displaced into the core at a constant pressure, and after the pressure is stabilized for a preset aging time, which comprises: after the simulation of the gas-water charging process in the reservoir-forming stage is completed, the core holder outlet valve is closed, the displacement pump pressure is set to the original formation pressure of the target block, the natural gas in the first intermediate container is constantly displaced into the core at a constant pressure, the core holder inlet valve and the upper and lower valves of the first intermediate container are closed after the pressure is stabilized for 2 hours, and the preset aging time is set.

[0068] Optionally, the continuing to simulate the depletion production stage and obtaining the plurality of T2 spectrum curves of the depletion production stage comprises: after the aging for the preset time, setting the back pressure pump pressure, opening the core holder outlet end valve, and performing the depletion production simulation in a gradient pressure reduction manner; through the nuclear magnetic resonance signal analysis system, when there is no gas production in the drainage gas recovery device, measuring the plurality of T2 spectrum curves after the depletion production simulation at different gradient back pressures; and when the depletion production reaches the preset abandonment pressure, stopping the depletion production simulation.

[0069] Optionally, the continuing to simulate the gas injection enhanced recovery stage and obtaining the plurality of T2 spectrum curves of the gas injection enhanced recovery stage comprises: after the depletion production reaches the preset abandonment pressure, opening the core holder inlet end valve and the upper and lower valves of the second intermediate container, presetting the injection pressures of the plurality of displacement pumps, and injecting the displacement agent in the second intermediate container at a constant pressure; through the nuclear magnetic resonance signal analysis system, when there is uniform gas production in the drainage gas recovery device, measuring the plurality of T2 spectrum curves after the gas injection enhanced recovery simulation at different injection pressures.

[0070] Optionally, the displacement agent is an injection gas, and the injection gas is one of N2, CO2 or air. The device herein can be a server, a PC, a PAD, a mobile phone, etc.

[0071] The application further provides a computer program product, which, when executed on a data processing device, is adapted to execute a program for initializing the following method steps: building an online nuclear magnetic core displacement experiment device; debugging test parameters of the online nuclear magnetic core displacement experiment device; according to the online nuclear magnetic core displacement experiment device, simulating a gas and water filling process of a reservoir forming stage for a dry core, and obtaining a plurality of T2 spectrum curves of the reservoir forming stage, wherein the dry core is obtained after being processed by a core of a target block; after the simulation of the gas and water filling process of the reservoir forming stage is completed, displacing natural gas into the core at a constant pressure, and after the pressure is stabilized, aging for a preset time; after the aging for the preset time, according to the online nuclear magnetic core displacement experiment device, continuing to simulate a depletion production stage, and obtaining a plurality of T2 spectrum curves of the depletion production stage; and after the simulation of the depletion production stage is completed, according to the online nuclear magnetic core displacement experiment device, continuing to simulate a gas injection enhanced recovery stage, and obtaining a plurality of T2 spectrum curves of the gas injection enhanced recovery stage.

[0072] Optionally, the online NMR core displacement experiment device comprises a power system, a test system, a metering system and an NMR signal analysis system, wherein the power system comprises a displacement pump, a first intermediate container and a second intermediate container, the first intermediate container is filled with natural gas, the second intermediate container is filled with a displacement agent, the displacement pump is used to displace the natural gas or the displacement agent in the intermediate containers, and the first intermediate container and the second intermediate container are both provided with upper and lower valves; the test system comprises a non-magnetic core holder, a confining pressure pump, a magnet, a back pressure valve and a back pressure pump, a probe and core holder inlet and outlet valves, the non-magnetic core holder is used to fix a core, the confining pressure pump is used to apply confining pressure to the core, the magnet is used to magnetize protons of fluid in the core, the probe is used to excite and receive NMR signals of the core, and the back pressure valve and the back pressure pump are used to control the pressure at the core holder outlet; the metering system comprises a first measuring cylinder and a drainage gas production device, the first measuring cylinder is used to collect and meter the amount of produced liquid, and the drainage gas production device comprises a second measuring cylinder and a water tank, which are used to collect and meter the volume of produced gas; and the NMR signal analysis system comprises a computer and an NMR spectrometer, the NMR spectrometer is used to control and emit RF pulse signals to excite NMR signals of a sample and to control and receive NMR signals of the core, and the computer is used to control the NMR spectrometer to excite and receive NMR signals of the sample and to perform inversion on the acquired echo trains to obtain T2 spectrum curves.

[0073] Optionally, the test parameters of the online NMR core displacement experiment device are debugged, which comprises debugging system parameters of the NMR signal analysis system, wherein the system parameters comprise echo time intervals, waiting times, echo numbers, scanning times and experimental temperatures.

[0074] Optionally, the gas-water charging process in the reservoir formation stage is simulated for the dry core according to the online NMR core displacement experiment device, and a plurality of T2 spectrum curves in the reservoir formation stage are obtained, which comprises the following steps: after the dry core is pressurized to simulate water saturation in the formation, the core is loaded into the non-magnetic core holder, the back pressure pump pressure is set, the core holder inlet and outlet valves and the upper and lower valves of the first intermediate container are opened, and the gas-water charging process in the reservoir formation stage is simulated by using the step-by-step pressurized gas displacement method; and a plurality of T2 spectrum curves after the gas-water charging in the initial and different pressure gradients in the reservoir formation stage are respectively measured by the NMR signal analysis system when uniform gas production occurs in the drainage gas production device.

[0075] Optionally, the constant pressure displacement of the natural gas into the core, after the pressure is stable, the aging of the preset time comprises: after the simulation of the gas-water filling process of the reservoir forming stage is completed, the outlet end valve of the core holder is closed, the displacement pump pressure is set as the original formation pressure of the target block, the natural gas in the first intermediate container is constantly displaced into the core, after the pressure is stable for 2 hours, the inlet end valve of the core holder and the upper and lower valves of the first intermediate container are closed, and the aging of the preset time is performed.

[0076] Optionally, the continuing simulation of the depletion production stage and obtaining a plurality of T2 spectrum curves of the depletion production stage comprises: after the aging of the preset time, the back pressure pump pressure is set, the outlet end valve of the core holder is opened, and the depletion production simulation is performed in a gradient pressure reduction manner; when there is no gas production in the drainage gas recovery device, a plurality of T2 spectrum curves after the depletion production simulation of different gradient back pressures are measured by the nuclear magnetic resonance signal analysis system; and when the depletion production reaches a preset abandonment pressure, the depletion production simulation is stopped.

[0077] Optionally, the continuing simulation of the gas injection enhanced recovery stage and obtaining a plurality of T2 spectrum curves of the gas injection enhanced recovery stage comprises: after the depletion production reaches the preset abandonment pressure, the inlet end valve of the core holder and the upper and lower valves of the second intermediate container are opened, a plurality of injection pressures of the displacement pump are preset, and the displacement agent in the second intermediate container is injected at a constant pressure; when the drainage gas recovery device uniformly produces gas, a plurality of T2 spectrum curves after the gas injection enhanced recovery simulation of different injection pressures are measured by the nuclear magnetic resonance signal analysis system.

[0078] Optionally, the displacement agent is an injection gas, and the injection gas is one of N2, CO2 or air.

[0079] Those skilled in the art will understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt a computer program product in the form of one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0080] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0081] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0082] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0083] In one typical configuration, the computing device includes one or more processors, input / output interfaces, network interfaces, and memory.

[0084] The memory can include non-persistent memory and / or persistent memory, such as flash memory, read-only memory (ROM), and / or volatile or non-volatile random access memory (RAM), among others. The memory is an example of computer-readable media.

[0085] Computer-readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0086] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0087] In the technical solutions of the present application, "the acquisition, transmission, storage, use, processing, etc. of data all comply with relevant provisions of national laws and regulations", and "it should be noted that in the embodiments of the present application, some industry existing solutions such as software, components, models, etc. may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but does not mean that the applicant has or will necessarily use the solutions.

[0088] The above is only an embodiment of the present application and is not used to limit the present application. The present application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the scope of claims of the present application.

Claims

1. A method for simulating gas and water occurrence and movement in a full life cycle of a low-permeability tight gas reservoir, characterized in that, The method comprises: building an online nuclear magnetic core displacement experiment device; debugging test parameters of the online nuclear magnetic core displacement experiment device; simulating a gas and water charging process of a reservoir stage according to the online nuclear magnetic core displacement experiment device, and obtaining a plurality of T2 spectrum curves of the reservoir stage; after the simulation of the gas and water charging process of the reservoir stage is completed, displacing natural gas into the core at a constant pressure, and aging for a preset time after the pressure is stable; after the preset time, continuing to simulate a depletion production stage according to the online nuclear magnetic core displacement experiment device, and obtaining a plurality of T2 spectrum curves of the depletion production stage; and after the simulation of the depletion production stage is completed, continuing to simulate a gas injection enhanced oil recovery stage according to the online nuclear magnetic core displacement experiment device, and obtaining a plurality of T2 spectrum curves of the gas injection enhanced oil recovery stage.

2. The method for simulating gas-water occurrence and movement in the whole life cycle of low-permeability tight gas reservoirs according to claim 1, characterized in that, The online nuclear magnetic core displacement experiment device comprises: a power system comprising a displacement pump (2), a first intermediate container (3) and a second intermediate container (5), wherein the first intermediate container (3) contains natural gas, the second intermediate container (5) contains a displacement agent, the displacement pump (2) is used to displace the natural gas or the displacement agent in the intermediate container, and upper and lower valves are installed at the upper and lower ends of the first intermediate container (3) and the second intermediate container (5); a test system comprising a non-magnetic core holder (14), a confining pressure pump (1), a magnet (7), a back pressure valve (16) and a back pressure pump (17), a probe (8), and a core holder inlet end valve (6) and a core holder outlet end valve (15), wherein the non-magnetic core holder (14) is used to fix a core, the confining pressure pump (1) is used to apply confining pressure to the core, the magnet (7) is used to magnetize the protons of the fluid in the core, the probe (8) is used to excite and receive the nuclear magnetic resonance signal of the core, and the back pressure valve (16) and the back pressure pump (17) are used to control the pressure at the outlet end of the core holder; a metering system comprising a first measuring cylinder (18) and a drainage gas recovery device, wherein the first measuring cylinder (18) is used to collect and meter the amount of produced liquid, and the drainage gas recovery device comprises a second measuring cylinder (11) and a water tank (19) for collecting and metering the volume of produced gas; and a nuclear magnetic resonance signal analysis system comprising a computer (10) and a nuclear magnetic resonance spectrometer (9), wherein the nuclear magnetic resonance spectrometer (9) is used to control and emit a radio frequency pulse signal to excite the core to generate a nuclear magnetic resonance signal, and to control and receive the nuclear magnetic resonance signal generated by the core, and the computer (10) is used to control the nuclear magnetic resonance spectrometer (9) to excite and receive the nuclear magnetic resonance signal of the core, and to obtain a T2 spectrum curve by inverting the collected echo train.

3. The method for simulating gas-water occurrence and movement in the whole life cycle of low-permeability tight gas reservoirs according to claim 2, characterized in that, The debugging of the test parameters of the online nuclear magnetic core displacement experiment device comprises debugging system parameters of the nuclear magnetic resonance signal analysis system, wherein the system parameters comprise echo time intervals, waiting times, echo numbers, scanning times and experimental temperatures.

4. The method for modeling gas-water occurrence and movement in the full life cycle of low-permeability tight gas reservoirs according to claim 1, characterized in that, The method further comprises: determining a conversion coefficient C of a relaxation time T2 and a pore size r according to a dry core; and According to the conversion coefficient C, the coordinate axis relaxation time T2 in the plurality of T2 spectrum curves is converted into the aperture r, wherein The conversion coefficient C of the relaxation time T2 and the aperture r is determined according to the dry core, comprising: Taking part of the dry core; The mercury injection experiment is performed on the dry core to determine the aperture distribution curve of the dry core; Taking another part of the dry core, after the dry core is saturated with simulated formation water under pressure, the T2 spectrum curve is determined; According to the aperture distribution curve and the T2 spectrum curve, the NMR-mercury injection aperture distribution contrast curve is determined; and According to the NMR-mercury injection aperture distribution contrast curve, the conversion coefficient C of the relaxation time T2 and the aperture r is determined by the formula: T2=Cr. The dry core is saturated with simulated formation water under pressure, comprising:

5. The method for simulating gas-water occurrence and movement in the whole life cycle of low-permeability tight gas reservoirs according to claim 4, characterized in that, The dry core is washed and dried; The dried core is placed in a vacuum device, and a turbine molecular pump is used to vacuum the core; The turbine molecular pump valve is closed, the intermediate container containing the simulated formation water is opened, and the simulated formation water is self-sucked into the vacuum device; and The displacement pump valve is opened, the pressure is set to a pre-set constant pressure, the simulated formation water in the intermediate container is displaced into the vacuum device, and the core is saturated under pressure for a pre-set time. According to the online NMR core displacement experiment device, the gas-water charging process of the reservoir-forming stage is simulated, and a plurality of T2 spectrum curves of the reservoir-forming stage are obtained, comprising:

6. The method for modeling gas-water occurrence and movement in the full life cycle of low-permeability tight gas reservoirs according to claim 2, characterized in that, The core saturated with simulated formation water is loaded into the non-magnetic core holder (14), the back pressure pump (17) pressure is set, the core holder inlet valve (6), core holder outlet valve (15) and upper and lower valves of the first intermediate container (3) are opened, and the gas-water charging process of the reservoir-forming stage is simulated by using the step-by-step pressurization gas drive method; and When the drainage gas production device is uniformly gas-producing, a plurality of T2 spectrum curves after the gas-water charging of the initial and different pressure gradients in the reservoir-forming stage are respectively determined by the NMR signal analysis system. The natural gas is displaced into the core at a constant pressure, and after the pressure is stable, the core is aged for a pre-set time, comprising:

7. The method for modeling gas-water occurrence and movement in the full life cycle of low-permeability tight gas reservoirs according to claim 2, characterized in that, After the simulation of the gas-water charging process of the reservoir-forming stage is completed, the core holder outlet valve (15) is closed, the displacement pump (2) pressure is set to the original formation pressure of the target block, the natural gas in the first intermediate container (3) is displaced into the core at a constant pressure, after the pressure is stable for 2 hours, the core holder inlet valve (6) and the upper and lower valves of the first intermediate container (3) are closed, and the core is aged for a pre-set time. The depletion simulation is continued, and a plurality of T2 spectrum curves of the depletion stage are obtained, comprising:

8. The method for simulating gas-water occurrence and movement in the whole life cycle of low-permeability tight gas reservoirs according to claim 7, characterized in that, After the pre-set aging time, the back pressure pump (17) pressure is set, the core holder outlet valve (15) is opened, and the depletion simulation is performed by using the gradient pressure reduction method; When there is no gas production in the drainage gas production device, a plurality of T2 spectrum curves after the depletion simulation of different gradient back pressures are respectively determined by the NMR signal analysis system; and When the depletion simulation reaches a pre-set abandonment pressure, the depletion simulation is stopped. ​ 9. The method for simulating gas-water occurrence and movement in the whole life cycle of low-permeability tight gas reservoirs according to claim 8, characterized in that, The continuing simulation of the gas injection enhanced recovery stage, and obtaining a plurality of T2 spectrum curves of the gas injection enhanced recovery stage comprises: After the depletion production to the preset abandonment pressure, the core holder inlet valve (6) and the upper and lower valves of the second intermediate container (5) are opened, the injection pressure of a plurality of the displacement pumps (2) is preset, and the displacement agent in the second intermediate container (5) is injected at a constant pressure; Through the nuclear magnetic resonance signal analysis system, when the gas is uniformly produced in the drainage gas production device, a plurality of T2 spectrum curves after the gas injection enhanced recovery simulation under different injection pressures are measured.

10. The method for modeling gas-water occurrence and movement throughout the life cycle of a low-permeability, tight gas reservoir according to claim 9, wherein, The displacement agent is an injected gas, and the injected gas is one of N2, CO2 or air.

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