Thermochemistry-assisted steam core displacement experimental device and experimental method

Abstract

The invention discloses a thermochemistry-assisted steam core displacement experimental device which comprises a high-temperature core holder, a pretreated core is arranged in the high-temperature core holder and comprises a heat shrink tube and a core, porous filter discs are in close contact with the two ends of the core, and the peripheries of the core and the filter discs are in close contact with the inner wall of the heat shrink tube; the first end of the control valve is communicated to a confining pressure pressurizing opening of the high-temperature core holder; the second end of the control valve is communicated to the first end of the high-temperature steam generator, the third end of the control valve is communicated to the first end of the displacement reagent container, and the fourth end of the control valve is communicated to a liquid inlet of the high-temperature core holder; the metering device is used for accommodating the liquid outlet pipe; and the constant-temperature container is used for keeping the temperature of the high-temperature core holder constant. The device can effectively enhance the mechanical strength of the rock core on the premise of keeping the original physicochemical properties of the rock core, and can be compatible with a thermochemistry-assisted steam displacement experiment system and a nuclear magnetic resonance detection technology. The invention further discloses a thermochemistry-assisted steam core displacement experiment method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil exploitation, and particularly relates to a thermal-chemical-assisted steam core displacement experimental device and an experimental method. BACKGROUND

[0002] In oilfield development and reservoir evaluation research, core displacement experiment, as a core means for understanding reservoir percolation law and optimizing exploitation scheme, its reliability is directly related to the scientificity of development decision. Crude oil, as a complex mixture of hydrocarbons, not only exists as a reservoir fluid in the original reservoir environment, but also forms a natural cementation network between rock particles through the adsorption and film formation of its viscosity and colloid-asphaltene components, and this feature is particularly significant in low-permeability and unconsolidated sandstone reservoirs. However, in the process of conventional displacement experiment, as water flooding, gas flooding or chemical flooding continue, the crude oil in the core is continuously replaced, and the decrease of oil saturation leads to the gradual loss of this natural cementation, and further causes the deterioration of the integrity of the core structure. This degradation of mechanical properties often manifests as particle shedding and structure disintegration in subsequent high-precision nuclear magnetic resonance scanning, CT imaging and other detection links, not only causing experimental data distortion, but also possibly causing irreversible damage to expensive detection equipment. More importantly, this structural instability phenomenon will seriously affect the repeated use value of the same rock sample in multiple rounds and multiple methods of displacement experiment, greatly restricting the depth and efficiency of reservoir comprehensive evaluation.

[0003] The current solutions to the problem of core structure stability mainly have two limitations: the physical method such as low-temperature preservation is simple to operate, but can only temporarily inhibit particle migration and cannot fundamentally improve the mechanical properties of the core; the chemical reinforcing agent can improve the strength of the core, but inevitably changes the original wettability and pore structure characteristics of the rock, which is unacceptable for experimental research that needs to accurately characterize the original state of the reservoir, especially in thermal-chemical-assisted steam displacement experiments involving complex physical and chemical processes, the traditional reinforcing method may interfere with the real mechanism of steam and reservoir rock, resulting in systematic deviation between the percolation parameters obtained by the experiment and the actual situation. This technical bottleneck makes researchers often face a dilemma: either bear the risk of data caused by core fragmentation, or accept the experimental error introduced by the reinforcing treatment, and this dilemma is particularly prominent in steam displacement experiments under high temperature and high pressure conditions.

[0004] In the prior art, nuclear magnetic resonance (NMR) imaging technology has been widely used in the quantitative study of oil-water distribution, pore structure and percolation channel evolution after core experiment due to its non-destructive, high resolution, no need for staining process and other advantages. Through the nuclear magnetic transverse relaxation time (T2) spectrum and two-dimensional imaging, the fluid content change, remaining oil enrichment area distribution and oil-water interface migration trend under different pore scales can be obtained, the visualization expression of the internal micro-displacement process of the core is realized, and the NMR can also be used for the comparison of oil saturation before and after displacement, which provides a scientific basis for the accurate determination of oil displacement efficiency and the optimization of experimental scheme. However, the integrity of the sample is required to be extremely high for nuclear magnetic imaging, and any slight damage to the core structure will cause imaging artifacts, signal loss or image distortion, thereby affecting the accuracy of the analysis results. Therefore, in the thermal chemical flooding experiment involving high temperature, strong reactivity chemical agent and physical disturbance, maintaining the stability of the core structure is a prerequisite to ensure the reliability of the nuclear magnetic scanning results.

[0005] The core of the thermal chemical assisted steam displacement technology as an important method for improving the recovery efficiency of heavy oil reservoir is to cooperatively utilize the dual action of thermodynamic energy and chemical agent to improve the flowability of crude oil. In actual application, the interaction mechanism among “steam-chemical agent-reservoir rock” needs to be accurately mastered, and this cognition mainly depends on the high-quality data obtained from indoor core displacement experiment. However, there is a key defect in the existing experimental system: under the combined action of high-temperature steam and chemical agent, the instability risk of the core structure is significantly increased, which not only affects the accurate collection of percolation parameters in the displacement process, but also may lead to the failure of subsequent nuclear magnetic resonance, CT imaging and other means or the acquisition of distorted image data, thereby affecting the interpretation accuracy of core indicators such as remaining oil distribution and pore structure evolution. Especially in the multi-round comparison experiment or dynamic experiment tracking, once the core structure is damaged, not only the continuity of the experiment will be lost, but also the high-quality rock sample resources will be seriously wasted.

[0006] In view of the above technical challenges, it is urgent to establish a systematic solution to meet the following three key requirements: first, the core can be moderately strengthened before the displacement experiment to ensure the stability of the structure in the subsequent high-temperature and high-pressure displacement and detection process; second, the strengthening method cannot significantly change the original pore structure and wettability characteristics of the core, so as to ensure the authenticity of the displacement experiment and the representativeness of the data; finally, it should have good compatibility with the existing thermal chemical assisted steam displacement experimental system and nuclear magnetic resonance detection technology. SUMMARY

[0007] To solve the above problems, the application provides a thermal-chemical auxiliary steam core displacement experiment device and an experiment method, which can effectively enhance the mechanical strength of a core under the premise of keeping the original physical and chemical properties of the core, improve the success rate and data quality of the core displacement experiment, provide a more reliable experimental basis for parameter optimization of the thermal-chemical auxiliary steam displacement technology, realize experimental evaluation of efficient and reliable development of a heavy oil reservoir, facilitate optimization of an oil displacement process, and have good compatibility with an existing thermal-chemical auxiliary steam displacement experiment system and nuclear magnetic resonance detection technology.

[0008] The application provides a thermal-chemical auxiliary steam core displacement experiment device, which comprises:

[0009] A high-temperature core holder, in which a pretreated core is placed, the pretreated core comprising a heat-shrinkable tube and a core located in the heat-shrinkable tube, both ends of the core being in close contact with porous filter sheets, and the outer circumferential portions of the core and the filter sheets being in close contact with the inner wall of the heat-shrinkable tube;

[0010] A control valve, a first end of which is communicated to a confining pressure pressurizing port of the high-temperature core holder, for adding liquid into the high-temperature core holder to form confining pressure;

[0011] A second end of the control valve is communicated to a first end of a high-temperature steam generator, a third end is communicated to a first end of a displacement reagent container, and a fourth end is communicated to a liquid inlet of the high-temperature core holder, for inputting high-temperature steam and displacement reagents into the high-temperature core holder;

[0012] A metering device, for accommodating a liquid outlet pipe communicated to a liquid outlet of the high-temperature core holder;

[0013] A constant-temperature container, for accommodating the high-temperature core holder and keeping the temperature of the high-temperature core holder constant.

[0014] Preferably, in the above-mentioned thermal-chemical auxiliary steam core displacement experiment device, a second end of the high-temperature steam generator is connected to a first end of a three-way valve, a second end of the three-way valve is sequentially connected to a constant-pressure constant-speed pump and a distilled water storage device, and a third end of the three-way valve is connected to a second end of the displacement reagent container.

[0015] Preferably, in the above-mentioned thermal-chemical auxiliary steam core displacement experiment device, a first valve is further arranged between the three-way valve and the high-temperature steam generator, and a second valve is further arranged between the three-way valve and the second end of the displacement reagent container.

[0016] Preferably, in the above-mentioned thermal-chemical auxiliary steam core displacement experiment device, a third valve and a check valve are arranged on a pipeline between the second end of the control valve and the first end of the high-temperature steam generator.

[0017] Preferably, in the above-mentioned thermal-chemical assisted steam core displacement experimental device, a fourth valve and a first pressure detection component are arranged on the pipeline between the first end of the control valve and the confining pressure pressurizing port of the high-temperature core holder.

[0018] Preferably, in the above-mentioned thermal-chemical assisted steam core displacement experimental device, a fifth valve and a second pressure detection component are arranged on the pipeline between the fourth end of the control valve and the liquid inlet port of the high-temperature core holder.

[0019] Preferably, in the above-mentioned thermal-chemical assisted steam core displacement experimental device, a sixth valve is arranged on the liquid outlet pipe.

[0020] The present application provides a thermal-chemical assisted steam core displacement experimental method, which utilizes the thermal-chemical assisted steam core displacement experimental device as claimed in any one of the above, and comprises the following steps:

[0021] The core and the filter sheets are placed in a heat-shrinkable tube, and the heat-shrinkable tube is heated to shrink inwardly so that the inner wall of the heat-shrinkable tube is in close contact with the outer circumferential part of the core and the filter sheets, thereby making a pretreated core;

[0022] The core is scanned by using nuclear magnetic resonance imaging to obtain initial basic parameters of the core;

[0023] The core is subjected to an alternating displacement experiment, and key indexes are monitored and calculated in real time during the experiment;

[0024] After the experiment, the core is scanned again by using nuclear magnetic resonance imaging to obtain final basic parameters of the core;

[0025] The final basic parameters and the initial basic parameters are used to obtain the porosity change rate and the oil saturation change rate generated by the alternating displacement.

[0026] Preferably, in the above-mentioned thermal-chemical assisted steam core displacement experimental method, the alternating displacement experiment on the core comprises the following steps:

[0027] The pretreated core is loaded into the high-temperature core holder, and the two end jacks of the high-temperature core holder are in contact with the pretreated core;

[0028] The high-temperature core holder is filled with liquid to form a confining pressure, and the high-temperature core holder is heated to a preset temperature by using a constant-temperature container;

[0029] After the displacement reagent is injected into the liquid inlet port of the high-temperature core holder to reach a preset pore volume, the injection is stopped, and a preset time is maintained;

[0030] Injecting high-temperature steam into the liquid inlet of the high-temperature core holder for displacement until the oil output of the liquid outlet of the high-temperature core holder is reduced to the minimum threshold of oil output, stopping displacement, and injecting displacement reagent again, repeating a preset number of times;

[0031] Recording the total liquid volume, oil production and pressure change data in each time interval until the water cut of the displaced fluid rises to the preset maximum threshold, stopping displacement.

[0032] Preferably, in the above-mentioned thermal-chemical-assisted steam core displacement experiment method, the real-time monitoring and calculation of key indicators during the experiment include:

[0033] The overall permeability of the pretreated core is calculated by the formula K = Q L 总 is the overall permeability, Q is the fluid volume flow rate, μ is the fluid viscosity, L 总 is the total length of the pretreated core, and ΔP 总 is the pressure difference between the two ends of the pretreated core.

[0034] The permeability K1 and K3 of the filter is calculated by the formula N is the number of holes on the filter, r is the radius of the hole, and A is the cross-sectional area of the core.

[0035] The permeability of the core is calculated by the formula K = K1 L1 + K3 L3 L2

[0036] The porosity of the core is calculated by the formula V p is the core pore volume, V t is the core volume, , wherein M is the weight of the pretreated core after being saturated with water, m1 is the weight of the first filter, m2 is the weight of the second filter, m3 is the weight of the heat shrink tube, m4 is the weight of the core in the dried state, V 滤1 is the volume of the hole of the first filter, V 滤2 is the volume of the hole of the second filter, and ρ w is the density of distilled water.

[0037] In summary, the thermal chemical auxiliary steam core displacement experiment device provided by the application has the advantages that: the high-temperature core holder is provided, the pretreated core is placed in the high-temperature core holder, the pretreated core comprises a heat shrink tube and a core arranged in the heat shrink tube, the two ends of the core are in close contact with the porous filter sheets, the outer circumferential portions of the core and the filter sheets are in close contact with the inner wall of the heat shrink tube, therefore, the core will not be deformed during displacement, and the core can be conveniently subjected to nuclear magnetic resonance examination, the control valve is provided, the first end of the control valve is communicated with the confining pressure pressurizing port of the high-temperature core holder, the control valve is used for adding liquid into the high-temperature core holder to form confining pressure, so that the core can be kept in a constant pressure state, the second end of the control valve is communicated with the first end of the high-temperature steam generator, the third end of the control valve is communicated with the first end of the displacement reagent container, and the fourth end of the control valve is communicated with the liquid inlet of the high-temperature core holder, so that the high-temperature steam and the displacement reagent can be input into the high-temperature core holder, and the displacement in the alternating state can be realized, the metering device is provided, the liquid outlet pipe communicated with the liquid outlet of the high-temperature core holder is arranged in the metering device, so that the liquid displaced out of the core can be metered, the thermostatic container is further provided, the high-temperature core holder is arranged in the thermostatic container, and the temperature of the high-temperature core holder is kept constant, so that a constant-temperature environment is provided for the core, and therefore, the experimental device can effectively enhance the mechanical strength of the core under the premise of keeping the original physical and chemical properties of the core, improve the success rate and data quality of the core displacement experiment, provide a more reliable experimental basis for parameter optimization of the thermal chemical auxiliary steam displacement technology, realize experimental evaluation of efficient and reliable development of thickened oil reservoirs, facilitate optimization of oil displacement process, and have good compatibility with the existing thermal chemical auxiliary steam displacement experiment system and nuclear magnetic resonance detection technology. The thermal chemical auxiliary steam core displacement experiment method provided by the application has the same advantages as the thermal chemical auxiliary steam core displacement experiment device. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only are the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on the provided drawings.

[0039] Figure 1 The overall schematic diagram of an embodiment of the thermal chemical auxiliary steam core displacement experiment device provided by the present application is shown in the figure.

[0040] Figure 2 The detailed overall schematic diagram of the core holder in the thermal chemical auxiliary steam core displacement experiment device provided by the present application is shown in the figure.

[0041] Figure 3A detail schematic view of a pretreated core used in a thermal-chemical assisted steam core displacement experiment device provided by the present application is shown in the figure;

[0042] Figure 4 A schematic view of filter surface pores used in a thermal-chemical assisted steam core displacement experiment device provided by the present application is shown in the figure;

[0043] Figure 5 A schematic view of a cross section of the filter along the thickness direction used in a thermal-chemical assisted steam core displacement experiment device provided by the present application is shown in the figure;

[0044] Figure 6 A schematic view of an embodiment of a thermal-chemical assisted steam core displacement experiment method provided by the present application is shown in the figure;

[0045] Figure 7 A comparison chart of the porosity distribution before and after sample processing is shown in the figure;

[0046] Figure 8 T1 and T2 distribution charts of the core in different processes are shown in the figures;

[0047] Figure 9 A two-dimensional imaging chart of the sample after being saturated with water is shown in the figure;

[0048] Figure 10 A two-dimensional imaging chart of the sample after being alternately displaced is shown in the figure;

[0049] Figure 11 A chart of the experimentally determined oil displacement efficiency and water cut change is shown in the figure;

[0050] Figure 12 A comparison chart of the displacement effects of different test methods is shown in the figure. DETAILED DESCRIPTION

[0051] The core of the present application is to provide a thermal-chemical assisted steam core displacement experiment device and experiment method, which can effectively enhance the mechanical strength of the core while keeping the original physical and chemical properties of the core, improve the success rate and data quality of the core displacement experiment, provide a more reliable experimental basis for the parameter optimization of the thermal-chemical assisted steam displacement technology, realize the experimental evaluation of efficient and reliable development of heavy oil reservoirs, facilitate the optimization of oil displacement technology, and have good compatibility with the existing thermal-chemical assisted steam displacement experiment system and nuclear magnetic resonance detection technology.

[0052] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0053] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , Figure 1 is a whole schematic diagram of an embodiment of a thermal-chemical assisted steam core displacement experimental device provided by the present application, Figure 2 is a whole schematic diagram of a core holder in a thermal-chemical assisted steam core displacement experimental device provided by the present application, Figure 3 is a detailed schematic diagram of a pretreated core used in a thermal-chemical assisted steam core displacement experimental device provided by the present application, Figure 4 is a schematic diagram of a filter surface hole used in a thermal-chemical assisted steam core displacement experimental device provided by the present application, Figure 5 is a schematic diagram of a filter cross section along the thickness direction used in a thermal-chemical assisted steam core displacement experimental device provided by the present application, which can include:

[0054] a high-temperature core holder 1, from Figure 2 it can be seen that the structure of the high-temperature core holder 1 can include a liquid outlet 101, a left end top rod 102, a left end fixed nut 103, a high-temperature resistant glass glue 104 (used for sealing the pores between the pretreated core and the Teflon rubber), a confining pressure pressurizing port 105, a holder cavity 106, a right end fixed nut 107, a liquid inlet 108, a right end top rod 109, and a screw rod 100, and the high-temperature core holder 1 can be placed with a pretreated core 2 inside, so that the pretreated core 2 will not move during displacement, and the pretreated core 2 can include a heat shrink tube 21 and a core 22 inside it, as shown in Figure 3 both ends of the core 22 are in close contact with porous filter sheets 23, and the outer circumferential parts of the core 22 and the filter sheets 23 are in close contact with the inner wall of the heat shrink tube 21, so that all parts of the core are limited during displacement, in order to more clearly show the structure of the filter sheet 23, refer to Figure 4 and Figure 5 it can be seen that the surface of the filter sheet 23 is uniformly distributed with a plurality of filter holes 231, the diameter of the filter hole 231 can be but is not limited to 1mm as shown, the overall diameter of the filter sheet 23 can be but is not limited to 25mm as shown, and the thickness can be but is not limited to 5mm as shown, a ceramic filter sheet with a plurality of seepage holes can be used; Figure 4 Figure 4 Figure 5

[0055] ​​​A control valve 3, a first end 301 of which is connected to the confining pressure inlet 105 of the high-temperature core holder 1, for adding liquid to the high-temperature core holder 1 to form confining pressure, so that the core can be fixed in the high-temperature core holder 1, and it should be noted that in this case, the core can be more stably clamped in a high-temperature and high-pressure environment, ensuring the reliability of the displacement experiment, and the confining pressure can be adjusted to facilitate the simulation of different depths and pressure conditions of the oil reservoir, which helps to better simulate the real oil reservoir.

[0056] A second end 302 of the control valve 3 is connected to a first end 401 of the high-temperature steam generator 4, a third end 303 is connected to a first end 501 of the displacement reagent container 5, and a fourth end 304 is connected to the liquid inlet 108 of the high-temperature core holder 1, for inputting high-temperature steam and displacement reagent into the high-temperature core holder 1, and the displacement reagent can be a 0.5% dispersion viscosity reducer solution, and it should be noted that the high-temperature steam generator 4 can perform thermal recovery simulation experiments (such as steam flooding), which can improve the thermal displacement simulation capability and be more close to the development mode of heavy oil thermal recovery, and can adapt to more scenarios, and can also perform displacement experiments at multiple temperatures / phase states.

[0057] A metering device 6 is used to accommodate a liquid outlet pipe 7 connected to the liquid outlet 101 of the high-temperature core holder 1, and the liquid outlet pipe 7 can be but not limited to a metal conduit used to connect various instruments, and the metering device 6 can be preferably a graduated cylinder for measuring the liquid produced by the experiment;

[0058] A constant-temperature container 20 is used to accommodate the high-temperature core holder 1 and keep the temperature of the high-temperature core holder 1 constant, and the constant-temperature container 20 is the part enclosed by the dashed line shown in the figure Figure 1 The use of the constant-temperature container 20 can control the temperature of the entire displacement pipeline, and compared with the traditional local heating method using heating tape, the constant-temperature container 20 can better reduce the experimental error caused by temperature fluctuations, and the constant-temperature container 20 can simulate the formation temperature, and the depth of the oil reservoir in the formation is different, and the corresponding temperature of the constant-temperature container 20 is also different, so that the displacement behavior under different oil reservoir temperatures can be simulated, and the application range is wider.

[0059] In summary, the above-mentioned thermal chemical assisted steam core displacement experimental device provided by the present application includes a high-temperature core holder, a pretreated core is placed inside the high-temperature core holder, the pretreated core includes a heat shrink tube and a core inside the heat shrink tube, the two ends of the core are in close contact with porous filter sheets, and the outer circumferential portions of the core and the filter sheets are in close contact with the inner wall of the heat shrink tube, so that deformation does not occur during displacement, and nuclear magnetic resonance testing is facilitated, and the control valve is connected to the confining pressure pressurizing port of the high-temperature core holder at the first end, used for injecting liquid into the high-temperature core holder to form confining pressure, so that the core can maintain a constant pressure state, and the second end of the control valve is connected to the first end of the high-temperature steam generator, the third end is connected to the first end of the displacement reagent container, and the fourth end is connected to the liquid inlet of the high-temperature core holder, used for inputting high-temperature steam and displacement reagent into the high-temperature core holder, so that alternating displacement can be achieved, and the metering device is used for accommodating the liquid outlet pipe connected to the liquid outlet of the high-temperature core holder, so that the displaced liquid can be metered, and the thermostat container is used for accommodating the high-temperature core holder and keeping the temperature of the high-temperature core holder constant, so that a constant temperature environment can be provided for the core, so that the experimental device can keep the core temperature at the original formation temperature, improve the success rate and data quality of the core displacement experiment, provide a more reliable experimental basis for parameter optimization of the thermal chemical assisted steam displacement technology, realize experimental evaluation of efficient and reliable development of heavy oil reservoirs, facilitate optimization of oil displacement process, and have good compatibility with existing thermal chemical assisted steam displacement experimental systems and nuclear magnetic resonance detection technology.

[0060] In one specific embodiment of the above-mentioned thermal chemical assisted steam core displacement experimental device, the second end 402 of the high-temperature steam generator 4 is connected to the first end 801 of the three-way valve 8, the second end 802 of the three-way valve 8 is connected to the constant pressure constant speed pump 9 and the distilled water storage device 10 in turn, and the third end 803 of the three-way valve 8 is connected to the second end 502 of the displacement reagent container 5. The constant pressure constant speed pump 9 is used to accurately control the flow rate and pressure of the fluid used for displacement, and in this case, the distilled water in the distilled water storage device 10 can be pumped into the high-temperature steam generator 4 by using the constant pressure constant speed pump 9.

[0061] Further, the first valve 11 can be arranged between the three-way valve 8 and the high-temperature steam generator 4, so that the first valve 11 can be used to control the opening and closing of the position, to control whether the constant-pressure constant-flow pump 9 can pump distilled water into the high-temperature steam generator 4, and the second valve 12 can be arranged between the three-way valve 8 and the second end 502 of the displacement reagent container 5, so that the second valve 12 can be used to control whether the constant-pressure constant-flow pump 9 can pump the displacement reagent into the high-temperature core holder 1. In this case, when the first valve 11 is opened and the second valve 12 is closed, the constant-pressure constant-flow pump 9 can pump the distilled water in the distilled water storage device 10 into the high-temperature steam generator 4 to form high-temperature steam, and when the first valve 11 is closed and the second valve 12 is opened, the constant-pressure constant-flow pump 9 can pump the displacement reagent in the displacement reagent container 5 into the high-temperature core holder 1 through the control valve 3, and the two processes are alternately performed, so that the automatic high-temperature steam and chemical alternating displacement is realized.

[0062] Further, the third valve 13 and the check valve 14 can be arranged on the pipeline between the second end 302 of the control valve 3 and the first end 401 of the high-temperature steam generator 4, so that the third valve 13 can be used to control whether the high-temperature steam can enter the position where the control valve 3 is located, and the check valve 14 can prevent the high-temperature steam from returning to the high-temperature steam generator 4.

[0063] Further, the fourth valve 15 and the first pressure detection component 16 can be arranged on the pipeline between the first end 301 of the control valve 3 and the confining pressure pressurizing port 105 of the high-temperature core holder 1, so that the fourth valve 15 can be used to control whether the confining pressure is applied to the confining pressure pressurizing port 105, and when the confining pressure is applied, the fourth valve 15 can be closed to keep the confining pressure unchanged, and the first pressure detection component 16 can detect the confining pressure, and when the target confining pressure value is reached, the fourth valve 15 can be controlled to be closed to prevent the confining pressure from being too large, and when the confining pressure is too small, the fourth valve 15 can be controlled to be opened to increase the confining pressure.

[0064] On the basis of the above embodiment, the fifth valve 17 and the second pressure detection component 18 can be arranged on the pipeline between the fourth end 304 of the control valve 3 and the liquid inlet port 108 of the high-temperature core holder 1, so that the fifth valve 17 can be used to control whether the high-temperature steam or the displacement liquid can enter the high-temperature core holder 1, and the second pressure detection component 18 can be used to measure the displacement pressure in real time. Further, the sixth valve 19 can be arranged on the liquid outlet pipe 7, so that the sixth valve 19 can be used to control whether the liquid can flow out and flow into the metering device 6 for metering.

[0065] It should be further noted that the control valve 3 can be preferably a six-way valve, so that the communication of each component in the entire displacement experiment device can be controlled.

[0066] The application provides a heat-chemical auxiliary steam core displacement experiment method Figure 6 Figure 6 The application provides a heat-chemical auxiliary steam core displacement experiment method

[0067] S1: porous filter sheets are tightly contacted at both ends of the core, the core and the filter sheets are placed in a heat-shrinkable tube, the heat-shrinkable tube is heated to shrink inward, the inner wall of the heat-shrinkable tube is tightly contacted with the outer circumferential part of the core and the filter sheets, and a pretreated core is prepared;

[0068] It should be noted that in the traditional displacement process, as the crude oil is gradually replaced, the mechanical balance in the core is destroyed, the cementation between particles is weakened, especially in loose sandstone or weakly cemented reservoirs, and the core strength sharply decreases after displacement, and the structure is easy to collapse in subsequent CT scanning, nuclear magnetic resonance detection and other precision analysis processes, which seriously affects the accuracy and repeatability of experimental data; meanwhile, the existing core reinforcement technologies such as low-temperature preservation or chemical reinforcement agent treatment all have obvious defects, the former can only temporarily inhibit particle migration but cannot fundamentally improve the mechanical properties, and the latter can change the original wettability and pore structure of the rock, affecting the authenticity of the experimental results; in addition, for special displacement methods such as heat-chemical auxiliary steam displacement, the existing technology lacks a systematic solution to effectively enhance the mechanical strength of the core while maintaining the original physical and chemical properties of the core, resulting in a large number of core samples after displacement that cannot be reused, which seriously restricts the depth and efficiency of oil reservoir research. Therefore, it is necessary to pretreat the core before the experiment. In this step, the required materials can include: an actual core (d=25mm), a ceramic filter sheet (d=25mm, thickness of 5mm), a heat-shrinkable tube resistant to high temperature, a hot air gun, a craft knife and scissors. The processing steps include: selecting a regular core without fragmentation; placing ceramic filter sheets at both ends of the core; placing the core and the ceramic filter sheets at both ends into a heat-shrinkable tube resistant to high temperature; the core and the ceramic filter sheets at both ends are kept on the same center line, and the ceramic filter sheets at both ends are kept tightly attached to the core; the heat-shrinkable tube is heated using a hot air gun so that the heat-shrinkable tube is attached to the core and the ceramic filter sheets at both ends without gaps; the excess heat-shrinkable tube at both ends of the heat-shrunk core is trimmed using a craft knife and scissors.

[0069] S2: the core is scanned by nuclear magnetic resonance imaging to obtain initial basic parameters of the core;

[0070] ​It should be noted that nuclear magnetic resonance imaging is a non-destructive detection method based on the principle of nuclear magnetic resonance (NMR). By measuring the relaxation time and signal intensity of hydrogen nuclei in the core, the distribution of pore structure and fluid (such as water, oil, gas) can be analyzed. This technology has high resolution and three-dimensional imaging capability, which can accurately evaluate the reservoir properties (such as porosity, permeability, saturation), and distinguish between free fluid and bound fluid. Although its sensitivity to low hydrogen content samples is limited and the equipment cost is high, with its non-destructive, precise quantitative fluid characteristics, this technology is still one of the core means of modern core analysis. By scanning the core before and after the experiment, data such as oil saturation and permeability change before and after displacement can be obtained. This step uses nuclear magnetic resonance imaging (NMR) technology to scan the core, which can obtain basic parameters such as initial porosity and original oil saturation.

[0071] S3: Alternating displacement experiment is performed on the core, and key indicators are monitored and calculated in real time during the experiment;

[0072] These key indicators can include oil production, water cut, injection medium utilization efficiency, displacement pressure difference, and changes in output fluid composition. Specifically, the step of performing alternating displacement experiment on the core can include the following sub-steps:

[0073] S31: The pretreated core is loaded into the high-temperature core holder, and the top rods at both ends of the high-temperature core holder are in contact with the pretreated core;

[0074] S32: The liquid is injected into the high-temperature core holder to form the confining pressure, and the constant-temperature container is used to heat the high-temperature core holder to the preset temperature. In operation, the constant-pressure constant-speed pump is opened, the flow rate is adjusted, the corresponding fourth valve 15 is opened, the confining pressure port of the high-temperature core holder is pressurized, and when a certain pressure is reached, the injection is stopped, and the fourth valve 15 is closed. After the constant-temperature container is opened to the predetermined temperature and maintained for a period of time, each device is fully heated;

[0075] S33: The displacement reagent is injected into the liquid inlet of the high-temperature core holder until the preset pore volume is reached, and then stopped for a predetermined time. Specifically, the displacement reagent container 5 is first filled with displacement reagent and connected with the control valve 3 and the three-way valve 8, then the first valve 11 is kept closed, the second valve 12, the control valve 3, the fifth valve 17 and the sixth valve 19 at both ends of the high-temperature core holder are opened, the constant-pressure constant-speed pump 9 is opened, and the flow rate is adjusted. After the injection of the displacement reagent is started, the injection is controlled to stop when the injection amount reaches 0.2 pv, and all valves are closed after 2h;

[0076] S34: injecting high-temperature steam into the liquid inlet of the high-temperature core holder for displacement, specifically, the valve of the control valve 3 can be switched so that the high-temperature steam generator is connected to the high-temperature core holder, the constant-pressure constant-speed pump is opened, the first valve 11 is opened while keeping the second valve 12 closed, the steam temperature of the high-temperature steam generator is adjusted to 250°C, the injection rate is adjusted to 1 mL / min, and then the displacement is started, until the oil output at the liquid outlet of the high-temperature core holder is reduced to the lowest threshold value, the displacement is stopped, and the displacement reagent is injected again, and the process is repeated for a predetermined number of times;

[0077] S35: recording the total liquid volume, oil production, and pressure change data in each time interval until the water content of the displaced fluid rises to the preset highest threshold value, specifically, the total liquid volume and oil production in each time interval can be recorded by using the metering device 6, the pressure change data can be detected by using the second pressure detection component 18, and the displacement can be stopped when the water content of the displaced fluid rises to 99%.

[0078] S4: after the experiment is completed, the core is scanned again by using nuclear magnetic resonance imaging to obtain the final basic parameters of the core, so that the changes in porosity and oil saturation after displacement can be obtained.

[0079] S5: using the final basic parameters and the initial basic parameters, the porosity change rate and the oil saturation change rate generated by the alternating displacement are obtained.

[0080] By comparing the nuclear magnetic scanning data before and after displacement, the reliability and representativeness of the displacement experiment results can be verified, and finally the purpose of providing a reliable experimental evaluation method for oil and gas reservoir development and optimizing oil displacement process parameters is achieved.

[0081] In one specific embodiment of the above-mentioned thermal-chemical-assisted steam core displacement experiment method, real-time monitoring and calculation of key indicators during the experiment can include the following sub-steps:

[0082] S36: the overall permeability of the pretreated core is calculated by using the formula 总 K = Q L / (A μ ΔP) 总 wherein K is the overall permeability, Q is the fluid volume flow rate, μ is the fluid viscosity, L 总 is the total length of the pretreated core, and ΔP

[0083] S37: the permeability K1 and K3 of the filter are calculated by using the formula

[0084] S38: the permeability K1 and K3 of the filter are calculated by using the formula ​​The permeability of the core is calculated, wherein K1 is the permeability of the first filter, K3 is the permeability of the second filter, L1 is the thickness of the first filter, L3 is the thickness of the second filter, and L2 is the length of the core;

[0085] S39: the formula is used to calculate the porosity of the core, wherein V p is the pore volume of the core, V t is the volume of the core, , wherein M is the weight of the pretreated core after being saturated with water, m1 is the weight of the first filter, m2 is the weight of the second filter, m3 is the weight of the heat-shrinkable tube, m4 is the weight of the core in the dried state, V 滤1 is the volume of the hole of the first filter, V 滤2 is the volume of the hole of the second filter, and p w is the density of the distilled water.

[0086] The formula derivation used in each of the above sub-steps can be as follows:

[0087] The pressure difference during the displacement experiment is composed of two parts, one part is the pressure difference generated by the ceramic filter, and the other part is the pressure difference generated by the real core, which is derived from Darcy's law:

[0088] ,

[0089] can be obtained

[0090] ,

[0091] In the formula,

[0092] Q: fluid volume flow rate (unit: cm 3 / s or m 3 / s);

[0093] μ: fluid viscosity (unit: centipoise cP, 1 cP=10- 3 Pa·s);

[0094] K 总 : the overall permeability of the ceramic filter and the core (unit: D);

[0095] A: the cross-sectional area of the core (unit: m 2 );

[0096] L 总 : the total length of the pretreated core (unit: m);

[0097] ∆P 总 : the pressure difference between the two ends of the pretreated core (unit: atm, MPa or Pa, 1 atm=0.1 MPa);

[0098] Because the displacement pressure and permeability of the whole core will change after adding ceramic filter sheets at both ends of the core, the permeability and displacement pressure difference of the actual core are required.

[0099] ,

[0100] According to the Hagen-Poiseuille law, the pressure difference of a cylindrical capillary in the ceramic filter sheet in laminar flow is:

[0101] ,

[0102] where Q' is the flow rate of a single capillary (unit: cm 3 / s or m 3 / s), which is the filter hole mentioned above, and the "capillary" in the following is the same thing.

[0103] The total flow rate is the sum of the flow rates of all capillaries:

[0104] ,

[0105] Substitute into the single capillary pressure difference formula:

[0106] ,

[0107] Because all capillaries in the ceramic filter sheet are in parallel, the pressure difference of a single capillary is equal to the pressure difference of the whole ceramic filter sheet, that is, .

[0108] The displacement pressure difference of the ceramic filter sheet changes with the injection rate, which needs to be calculated in the actual experiment. According to the pressure difference relationship of series displacement, the relationship between the displacement pressure difference of the treated core and the displacement pressure differences of the ceramic filter sheet and the real core is:

[0109] ,

[0110] Therefore, ,

[0111] In the formula,

[0112] △P1: displacement pressure difference of the left ceramic filter sheet (unit: Pa);

[0113] △P2: displacement pressure difference of the real core (unit: Pa);

[0114] △P3: displacement pressure difference of the right ceramic filter sheet (unit: Pa);

[0115] The flow rate of a single capillary is: ,

[0116] The total flow rate is given by Darcy's law: ,

[0117] Solving the equations gives: ,

[0118] where,

[0119] μ: fluid viscosity (unit: centipoise cP, 1 cP = 10-3 Pa·s),

[0120] L: ceramic filter thickness (unit: centimeters cm,

[0121] Q: displacement flow rate (unit: m 3 / s),

[0122] π: the ratio of the circumference of a circle to its diameter,

[0123] r: capillary radius (unit: m),

[0124] N: the number of capillaries in the ceramic filter,

[0125] K: ceramic filter permeability (unit: D),

[0126] It can be seen that K1 and K3 can be calculated in this way.

[0127] Further, we have:

[0128] ,

[0129] In this way, the actual core permeability K2 is calculated.

[0130] where,

[0131] L 总 : the overall length of the ceramic filter plus the core (unit: m);

[0132] L1: the length of the left ceramic filter (unit: m);

[0133] K1: the permeability of the left ceramic filter (unit: D);

[0134] L2: the length of the actual core (unit: m);

[0135] K2: the permeability of the actual core (unit: D);

[0136] L3: the length of the right ceramic filter (unit: m);

[0137] K3: the permeability of the right ceramic filter (unit: D).

[0138] Regarding porosity determination:

[0139] The whole pretreated core porosity can be determined by the weighing method, wherein the pore volume of the ceramic filter is:

[0140] ,

[0141] In the formula,

[0142] V 滤 : the pore volume of the ceramic filter (unit: m 3 );

[0143] N: the number of capillaries in the ceramic filter;

[0144] r1: the capillary radius (unit: m);

[0145] h: the thickness of the ceramic filter (unit: m);

[0146] The ceramic filter, the core (after drying), and the high-temperature heat-shrinkable tube are weighed separately, assembled into a whole, placed into a high-temperature core holder, saturated with distilled water, weighed again, and then the porosity of the core can be calculated by using the above sub-step S39.

[0147] In summary, the present application provides a device and experimental method for carrying out thermo-chemical synergistic oil displacement experiments, which solves the problems of difficulty in real restoration of steam and chemical agent coupling, low integration of experimental devices, and weak quantitative analysis ability of experimental results in existing core physical simulation. The scheme takes the alternating displacement mechanism as the core, combines high temperature and high pressure control, multi-phase medium switching, and nuclear magnetic resonance imaging analysis means, and establishes a systematic, controllable and quantifiable experimental platform, which provides full-process technical support for the research of thermo-chemical assisted oil recovery mechanism.

[0148] In the technical scheme, first, a core displacement experimental device specially used for thermo-chemical synergistic oil displacement research is constructed, which integrates a steam generation and pressure stabilizing system, a chemical agent high-precision injection module, a core clamping and temperature control and insulation system, a six-way valve quick switching mechanism, and a produced liquid collection unit, can realize continuous or alternating injection of multi-component media in different stages, and meets the temperature, pressure, and flow control requirements of different experimental schemes. The structural design enables steam and chemical agents to be injected into the core in an orderly manner according to the set rhythm, and truly restores the dynamic process of steam-chemical agent synergistic displacement.

[0149] During the experiment, key experimental indicators such as oil production, water cut, injection medium utilization efficiency, displacement pressure difference, and changes in produced fluid composition at each stage were monitored through manual timed data acquisition and recording, providing data support for subsequent analysis. After the experiment, nuclear magnetic resonance imaging (NMR) was used to non-destructively scan the core to obtain images of the oil phase distribution before and after displacement, thereby analyzing key dynamic processes such as the distribution characteristics of residual oil inside the core, the migration path of the oil-water interface, and the advancement morphology of the thermal front. The oil displacement efficiency measured in the experiment was in high agreement with the NMR imaging analysis results, indicating that the experimental method has good scientific validity and data reliability, providing a solid foundation for the quantitative evaluation of the thermochemical synergistic oil displacement effect.

[0150] The thermochemical-assisted steam core displacement experimental apparatus and method provided in this application can be widely applied to the simulation of thermal recovery mechanisms and the evaluation of displacement effects in different types of heavy and extra-heavy oil reservoirs. It has strong systematicity, high structural integration, and good experimental repeatability. Furthermore, it introduces visual nuclear magnetic resonance methods for result evaluation, making the thermal recovery experimental results more quantitative, intuitive, and reliable. It can provide theoretical basis and experimental support for the design of on-site thermochemical development schemes, parameter optimization, and recovery rate improvement, and has good promotion value and engineering application prospects.

[0151] The following example illustrates in detail the application of the above-mentioned thermochemical-assisted steam core displacement experimental apparatus and method:

[0152] The core information used is as follows:

[0153] Porosity: 28.81%, Permeability: 643*10 -3 μm 2 Injection volume: 3PV or more, saturation: 70.57%, core length: 7.95cm, displacement rate: 1mL / min, concentration of dispersant and viscosity reducer: 0.5%, viscosity: 1337mpa·s.

[0154] The core samples were pretreated and subjected to NMR scanning. After resaturation with water, NMR scanning was performed again. An alternating displacement experiment was then conducted, and the results were recorded. After the cores cooled, NMR scanning was performed again. The following experimental results were obtained (for reference). Figure 7 , Figure 7 This is a comparison diagram of porosity distribution before and after sample treatment. Figure 7 The area enclosed by the curve and the time axis represents the porosity of the core. It can be seen that the initial porosity of the core is low, indicating very little water content, insufficient hydrogen nuclei, and a weak signal, resulting in low porosity. After saturation with water, the porosity increases significantly compared to the initial state. However, the porosity after alternating displacement is lower than that after water saturation, possibly due to the following reasons:

[0155] (1) Mineral shrinkage or particle reorganization: At high temperatures, water evaporates between clay minerals (such as montmorillonite), causing the mineral layer to shrink and some micropores to close, resulting in a decrease in short T2 signal (nanoscale pores) and a decrease in porosity; the thermal expansion coefficients of different minerals are not uniform, and local stress causes the pore throats to narrow.

[0156] (2) Changes in fluid phase and distribution: After thermal drive, some bound water is vaporized or driven out, and the pores originally occupied by water become "empty". However, some pores cannot be filled by gas due to capillary force, resulting in weakened nuclear magnetic signal; high temperature may cause heavy components (asphaltite) in crude oil to precipitate out and block the pore throat.

[0157] (3) Thermal decomposition and chemical reaction: Organic matter decomposes at high temperature to produce gas, but some solid residues may block the pores; for example, kaolinite is transformed into dense minerals (such as mullite) at high temperature, reducing the pore space.

[0158] refer to Figure 8 , Figure 8 The images show the T1 and T2 distributions of the core sample at different stages. From the initial T1 and T2 distributions, it can be seen that the core sample contained almost no free water in its initial state. Light green clumps are visible in the upper left of the image at T1 / T2=10, indicating strong binding and complete adsorption or restriction of the fluid. In the T2 spectrum above the image, the curve peak is relatively sharp with an indistinct tail on the right, indicating large pores or very little or no free water. In the T1 spectrum on the right side of the image, the curve peak has a tail, but it is not particularly long, reflecting strong restriction of water molecule activity. After the sample is saturated with water, the T1 and T2 distributions are shown in both the image and the image after alternating displacement. The signal is stronger between T1 / T2=1, 2, and 5, indicating high free water content and high porosity. The higher peak and longer tail of the T2 spectrum above the image also indicate larger porosity. The multiple peaks in the T1 spectrum on the right side of the image indicate the presence of multiple different water phases, such as clay-bound water, bound water, and free water.

[0159] refer to Figure 9 and Figure 10 , Figure 9 This is a two-dimensional image of the sample after it has been saturated with water. Figure 10 This is a two-dimensional imaging image of the sample after alternating drive, by Figure 9 It can be seen that the central red area is very concentrated, indicating that the middle part of the core is a high oil-bearing area. The irregular distribution suggests that the core pore structure has a certain degree of heterogeneity and high permeability channels exist. The light green color around the central red area indicates a weak signal, suggesting that the core edge is low porosity, low permeability, or does not contain oil. Figure 10For the image of core after alternate displacement, the red area is obviously reduced, especially in the lower part of the image, while part of the red color remains in the upper middle part, especially in the upper part, which is the outlet section of core displacement. It shows that after the displacement front breaks through, it preferentially passes through the high permeability channel, resulting in that part of the low permeability area at the outlet end is not fully swept, and there is more residual oil. The displacement effect is obvious in the middle part of the image, and the edge changes little, which is consistent with the characteristics of displacement along the main seepage channel.

[0160] Reference Figure 11 , Figure 11 For the experimental determination of oil displacement efficiency and water cut change graph, it can be seen that the oil displacement efficiency increases significantly, and the water cut decreases slightly after rapid rising, and rises to 99.09% to end the displacement.

[0161] Reference Figure 12 , Figure 12 For the displacement effect comparison chart of different test methods, Figure 12 The data shows that the oil displacement efficiency measured by the experiment is 54.85%, and the nuclear magnetic resonance scanning estimates 53.62%, with an error of only 1.23%, indicating that nuclear magnetic resonance can effectively reflect the displacement effect, and the alternate displacement method has good oil displacement performance and experimental consistency under the condition of the core. At the same time, the small difference between the two also shows that the experiment and measurement operation are more standardized, and there is no significant systematic error.

[0162] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.​

Claims

1. A thermochemical-assisted steam core displacement experimental apparatus, characterized in that, include: A high-temperature core holder contains a pre-treated core, which includes a heat-shrinkable tube and the core inside it. Both ends of the core are in close contact with a porous filter, and the outer periphery of the core and the filter are in close contact with the inner wall of the heat-shrinkable tube. A control valve, the first end of which is connected to the confining pressure port of the high-temperature core holder, is used to inject liquid into the high-temperature core holder to form confining pressure; The second end of the control valve is connected to the first end of the high-temperature steam generator, the third end is connected to the first end of the displacement reagent container, and the fourth end is connected to the liquid inlet of the high-temperature core holder, for inputting high-temperature steam and displacement reagent into the high-temperature core holder; A metering device for accommodating a liquid outlet pipe connected to the liquid outlet of the high-temperature core holder; A thermostatic container is used to contain the high-temperature core holder and maintain the temperature of the high-temperature core holder at a constant level.

2. The thermochemical-assisted steam core displacement experimental apparatus according to claim 1, characterized in that, The second end of the high-temperature steam generator is connected to the first end of the three-way valve, the second end of the three-way valve is connected in sequence to the constant pressure and constant speed pump and the distilled water storage device, and the third end of the three-way valve is connected to the second end of the displacement reagent container.

3. The thermochemical-assisted steam core displacement experimental apparatus according to claim 2, characterized in that, A first valve is also provided between the three-way valve and the high-temperature steam generator, and a second valve is also provided between the three-way valve and the second end of the displacement reagent container.

4. The thermochemical-assisted steam core displacement experimental apparatus according to claim 3, characterized in that, A third valve and a check valve are installed on the pipeline between the second end of the control valve and the first end of the high-temperature steam generator.

5. The thermochemical-assisted steam core displacement experimental apparatus according to claim 1, characterized in that, A fourth valve and a first pressure detection component are installed on the pipeline between the first end of the control valve and the confining pressure port of the high-temperature core holder.

6. The thermochemical-assisted steam core displacement experimental apparatus according to claim 1, characterized in that, A fifth valve and a second pressure detection component are installed on the pipeline between the fourth end of the control valve and the inlet of the high-temperature core holder.

7. The thermochemical-assisted steam core displacement experimental apparatus according to claim 1, characterized in that, A sixth valve is installed on the liquid outlet pipe.

8. A thermochemical-assisted steam core displacement experimental method, characterized in that, The thermochemical-assisted steam core displacement experimental apparatus as described in any one of claims 1-7 includes: Porous filter sheets are tightly contacted at both ends of the core. The core and the filter sheets are placed inside a heat shrink tubing. The heat shrink tubing is heated to shrink inward, so that the inner wall of the heat shrink tubing is in close contact with the outer periphery of the core and the filter sheets, thus creating a pretreated core. The core was scanned using nuclear magnetic resonance imaging to obtain the initial basic parameters of the core. Alternating displacement experiments were conducted on the core samples, and key indicators were monitored and calculated in real time during the experiments. After the experiment, the core was scanned again using nuclear magnetic resonance imaging to obtain the final basic parameters of the core. Using the final basic parameters and the initial basic parameters, the porosity change rate and oil saturation change rate generated by alternating displacement are obtained.

9. The thermochemical-assisted steam core displacement experimental method according to claim 8, characterized in that, The alternating displacement experiment on the core includes: The pretreated core is loaded into the high-temperature core holder, so that the top rods at both ends of the high-temperature core holder contact the pretreated core; Liquid is injected into the high-temperature core holder to form confining pressure, and the high-temperature core holder is heated to a preset temperature using a constant temperature container; After injecting a displacement agent into the inlet of the high-temperature core holder to reach a preset pore volume, the injection is stopped and maintained for a preset time. High-temperature steam is injected into the inlet of the high-temperature core holder for displacement until the oil output from the outlet of the high-temperature core holder drops to the minimum oil output threshold. Displacement is then stopped, and displacement reagent is injected again. This process is repeated a preset number of times. Record the total liquid volume, oil production, and pressure changes for each time interval until the water content of the displaced fluid rises to a preset maximum threshold, at which point the displacement stops.

10. The thermochemical-assisted steam core displacement experimental method according to claim 8, characterized in that, The real-time monitoring and calculation of key indicators during the experiment includes: Using formula Calculate the overall permeability of the pretreated core, where K 总 Let Q be the overall permeability, Q be the fluid volumetric flow rate, μ be the fluid viscosity, and L be the fluid viscosity. 总 ΔP is the total length of the pretreated core. 总 The pressure difference between the two ends of the pretreated core. Using formula Calculate the permeability K1 and K3 of the filter, where N is the number of pores on the filter, r is the radius of the pore, and A is the cross-sectional area of ​​the rock core; Using formula The permeability of the core was calculated, where K1 is the permeability of the first filter, K3 is the permeability of the second filter, L1 is the thickness of the first filter, L3 is the thickness of the second filter, and L2 is the length of the core. Using formula Calculate the porosity of the core, where V p V is the core pore volume. t For the core volume, Where M is the weight of the pretreated core after saturation with water, m1 is the weight of the first filter, m2 is the weight of the second filter, m3 is the weight of the heat shrink tubing, m4 is the weight of the core in the dried state, and V 滤1 V is the volume of the pores of the first filter. 滤2 ρ is the volume of the pores of the second filter. w This is the density of distilled water.

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