Experimental device and method for visual evaluation of injection-production seepage characteristics of fracture-vuggy gas storage

Abstract

The invention discloses an experimental device and method for visual evaluation of injection-production seepage characteristics of a fracture-vug type gas storage, and belongs to the technical field of gas storage. The device comprises a three-dimensional rock core model and cameras arranged on the periphery of the three-dimensional rock core model. The periphery of the three-dimensional rock core model is wrapped with a transparent shell, a plurality of insertion pipes are inserted into the three-dimensional rock core model, and the insertion pipes are connected with a gas-water main pipe; the three-dimensional rock core model is also communicated with a first pipeline and a second pipeline, the first pipeline is connected with a recovery container, and the second pipeline is connected with a vacuum pump; the three-dimensional rock core model is made of a transparent material. The experimental device provided by the invention can simulate the injection-production process, and is relatively simple in structure and easy to control and operate. Meanwhile, the three-dimensional rock core model is made of a visual transparent material, and the physical property of the material is close to that of an actual reservoir as much as possible, so that the experimental result is more reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of gas storage, and in particular relates to an experimental device and method for visually evaluating injection and production seepage characteristics of a fracture-cavity type gas storage. Background Art

[0002] Driven by the dual carbon goals of "carbon peak" and "carbon neutrality", natural gas, as an efficient green energy, plays a key role in energy transformation. With the continuous advancement of gas storage construction in the Sichuan Basin, new storage construction areas have further extended to highly heterogeneous carbonate gas reservoirs. The scientific and efficient construction of gas storages faces new problems in understanding the laws and influences of non-equilibrium special seepage characteristics of fracture-cavity bodies. The seepage characteristics between high-permeability fracture-cavity bodies and low-permeability matrices and the crossflow path of natural gas are still unclear.

[0003] The prior art discloses a measuring device and method for the diffusion coefficient of injected gas and liquid phase for fracture-cavity oil reservoirs. The measuring device includes: a constant speed and constant pressure pump, a piston intermediate container, a gas buffer tank, a reactor, a thermostat and a pressure data processing unit; the constant speed and constant pressure pump, the piston intermediate container, the gas buffer tank and the reactor are connected in sequence; the piston intermediate container, the gas buffer tank and the reactor are built in the thermostat; the pressure data processing unit is used to collect and monitor the outlet pressure of the piston intermediate container, the outlet pressure of the gas buffer tank and the inlet pressure of the reactor. The device can ensure the measurement accuracy when the injected gas diffuses by adding a gas buffer tank; the initial pressure value of the injected gas in contact with the liquid phase is obtained by using the gas state equation calculation method, which reduces the measurement error, and the accurate diffusion coefficient can be calculated by using Fick's second law of diffusion and the pressure depletion curve for nonlinear regression fitting. However, the above-mentioned measuring device and method are only used for the diffusion coefficient of injected gas and liquid phase in fracture-cavity oil reservoirs, and cannot be used for the evaluation of the injection and production seepage characteristics and the crossflow path of natural gas in fracture-cavity gas storage. Summary of the invention

[0004] In view of the above problems, the present invention provides an experimental device and method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage. The experimental device uses a three-dimensional core model made of transparent materials, simulates the injection and production process, adds colored gas to natural gas for dyeing, and uses a high-definition camera to observe the seepage path of the dyed natural gas and the deformation characteristics of the fracture-cavity body under alternating stress, thereby providing support for the design of the gas storage scheme. The present invention solves the problem that there is no relatively reliable experimental device and evaluation method for studying the injection and production seepage characteristics of fracture-cavity gas storage in the prior art, and there is no experimental device for visual evaluation of the injection and production seepage characteristics of fracture-cavity gas storage, which is used to assist in studying the seepage characteristics between the high-permeability fracture-cavity body and the low-permeability matrix and the crossflow path of natural gas.

[0005] The first object of the present invention is to provide an experimental device for visual evaluation of injection and production seepage characteristics of a fracture-cavity gas storage reservoir, the device comprising a three-dimensional core model and a camera arranged around the three-dimensional core model;

[0006] The outer periphery of the three-dimensional core model is wrapped with a transparent shell, and a plurality of plugs are inserted into the three-dimensional core model, and the plugs are connected to gas and water main pipes;

[0007] The three-dimensional core model is also connected to a first pipeline and a second pipeline, the first pipeline is connected to a recovery container, and the second pipeline is connected to a vacuum pump;

[0008] The three-dimensional core model is made of transparent material.

[0009] In an embodiment of the present invention, the gas-water main is also connected to a natural gas pipeline and a formation water pipeline, the natural gas pipeline and the formation water pipeline converge into the gas-water main, and pressure pumps are provided on the natural gas pipeline and the formation water pipeline.

[0010] In the embodiment of the present invention, a first pressure gauge and a flow meter are provided on the gas-water main pipe.

[0011] In an embodiment of the present invention, the first pressure gauge is disposed at the confluence of the natural gas pipeline and the formation water pipeline.

[0012] In an embodiment of the present invention, the natural gas pipeline and the formation water pipeline also converge into a third pipeline, and the confluence point is the first pressure gauge.

[0013] In an embodiment of the present invention, a back pressure pump and a second pressure gauge are provided on the first pipeline.

[0014] In an embodiment of the present invention, the camera signal is connected to a computer.

[0015] The second object of the present invention is to provide an experimental method for visually evaluating the injection and production seepage characteristics of a fracture-cavity gas storage reservoir, the method comprising:

[0016] Inserting a plurality of inserting tubes into the three-dimensional core model made of transparent material, wherein the inserting tubes are connected to the gas and water main pipes;

[0017] Connecting a first pipeline and a second pipeline on the three-dimensional core model, wherein the first pipeline is connected to a recovery container, and the second pipeline is connected to a vacuum pump;

[0018] Conduct injection and production seepage experiments in gas storage;

[0019] The camera takes pictures and records the three-dimensional core model in real time, and monitors the injection and production seepage characteristics of natural gas after it enters the three-dimensional core model.

[0020] In an embodiment of the present invention, the three-dimensional core model is made by the following steps:

[0021] Conduct CT scanning on the real reservoir core to be evaluated and construct a digital model of the pore network;

[0022] Inserting the reservoir fracture-cavity pattern obtained from seismic data or outcrop observation into the pore network digital model to obtain a three-dimensional digital core model;

[0023] The three-dimensional digital core model is manufactured into a three-dimensional core model (1) by 3D printing or casting.

[0024] In an embodiment of the present invention, the injection and production seepage characteristics include the seepage path of natural gas after entering the three-dimensional model; the crossflow path and equilibrium time of the fluid between the high-permeability fracture-cavity body and the low-permeability matrix during the injection and production process; and the changes in the fractures during the injection and production process.

[0025] Beneficial effects of the present invention:

[0026] 1. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage provided by the present invention can simulate the injection and production process, and the device structure is relatively simple and easy to control and operate. At the same time, the three-dimensional core model of the present invention is made of a visual transparent material, and the physical properties of the material are as close as possible to the actual reservoir, making the experimental results more reliable.

[0027] Seepage characteristics between high-permeability fracture-cavity bodies and low-permeability matrix and crossflow paths of natural gas

[0028] 2. The three-dimensional core model in the experimental device of the present invention uses the real reservoir core to be evaluated through CT scanning to establish a digital model of the pore network, and then inserts the reservoir fracture and cave pattern obtained from seismic data or outcrop observation, and is formed by 3D printing technology or casting technology. The obtained three-dimensional core model is closer to the digital core model of the actual reservoir, so that the final experimental results are closer to the actual situation and the evaluation results are more reliable.

[0029] 3. In the present invention, in order to more clearly observe the state of the fluid in the pores and cracks, the digital core model can be enlarged in proportion and then made into a three-dimensional core model for experiment.

[0030] Fourth, in the present invention, the storage capacity utilization characteristics of the gas storage reservoir under different injection and production speed and pressure conditions can be simulated, that is, the ratio of produced gas to injected gas, and the optimal injection and production speed and injection and production pressure under different fracture and cave combinations can be optimized.

[0031] 5. The experimental device and method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage provided by the present invention can realize the simulation of various scenarios, including one injection and one production, same injection and same production, and multiple injections and multiple productions.

[0032] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of an experimental device for visually evaluating injection and production seepage characteristics of a fracture-cavity gas storage according to an embodiment of the present invention is shown;

[0035] Figure 2 A pore network model diagram according to an embodiment of the present invention is shown;

[0036] Figure 3 It shows a seismic ant body tracking interpretation diagram of a fracture-cavity reservoir according to an embodiment of the present invention;

[0037] Figure 4 Shows Figure 3 Typical fracture-cavity cross-section depiction;

[0038] Figure 5 The outcrop photo of the fracture-cavity reservoir is shown;

[0039] Figure 6 Shows Figure 5 Depiction of the outcrop fracture and cave morphology.

[0040] In the figure:

[0041] 1. Three-dimensional core model; 1.1. Insertion; 2. Gas and water main pipe; 3. Natural gas pipeline; 4. Formation water pipeline; 5. First pressure gauge; 6. Flow meter; 7. First pipeline; 8. Recovery container; 9. Back pressure pump; 10. Second pressure; 11. Second pipeline; 12. Vacuum pump; 13. Camera; 14. Computer; 15. Pressure pump; 16. Third pipeline. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] like Figure 1 As shown, the experimental device for visual evaluation of injection and production seepage characteristics of a fracture-cavity gas storage according to an embodiment of the present invention comprises a three-dimensional core model 1 and a camera 13 arranged around the three-dimensional core model 1, wherein the camera 13 is used to take real-time photos and videos of the three-dimensional core model 1 to monitor the injection and production seepage characteristics of natural gas after entering the three-dimensional core model 1;

[0044] The outer periphery of the three-dimensional core model 1 is wrapped with a transparent shell, and the transparent shell is arranged to ensure the airtightness of the three-dimensional core model 1, so as to simulate that the three-dimensional core model 1 is in a vacuum state;

[0045] A plurality of cannulas 1.1 are inserted into the three-dimensional core model 1. The cannulas 1.1 pass through the transparent shell and are inserted into the three-dimensional core model 1. The cannulas 1.1 are connected to a gas-water main pipe 2. By setting a plurality of the cannulas 1.1, injection and production methods such as one injection and one production, simultaneous injection and simultaneous production, and multiple injections and multiple productions in the gas injection and production process are simulated;

[0046] The three-dimensional core model 1 is also connected to a first pipeline 7 and a second pipeline 11, wherein the first pipeline 7 is connected to a recovery container 8, and the second pipeline 11 is connected to a vacuum pump 12;

[0047] The three-dimensional core model 1 is made of transparent material, so that the interior of the three-dimensional core model 1 can be visualized, which is convenient for observing the seepage characteristics of the three-dimensional core model 1 during injection and production during the experiment.

[0048] In an embodiment of the present invention, the three-dimensional core model 1 is made by the following steps:

[0049] Step a, performing CT scanning on the real reservoir core to be evaluated and constructing a digital model of the pore network;

[0050] Step b: inserting the reservoir fracture-cavity pattern obtained from seismic data or outcrop observation into the pore network digital model to obtain a three-dimensional digital core model, specifically:

[0051] b11. Describe the fracture-cavity morphology of the reservoir to be evaluated traced by the seismic ant body, or the fracture-cavity morphology of the fracture-cavity reservoir outcrop;

[0052] b12, the fracture-cavity morphology after characterization is digitized to generate a data body by means of digital core software or MATLAB program, and inserted into the three-dimensional pore network in step a, and finally a three-dimensional digital core model of pore-cavity-fracture triple medium is formed;

[0053] Step c: manufacturing the three-dimensional digital core model into a three-dimensional core model 1 by 3D printing or casting.

[0054] In the embodiment of the present invention, a first pressure gauge 5 and a flow meter 6 are provided on the gas-water main pipe 2. The flow meter 6 is provided to facilitate control and monitoring of the injection speed of gas and water in the gas-water main pipe 2. The first pressure gauge 5 is provided to facilitate monitoring the pressure on the gas-water main pipe 2.

[0055] In an embodiment of the present invention, the gas-water main pipe 2 is also connected to a natural gas pipeline 3 and a formation water pipeline 4, the natural gas pipeline 3 and the formation water pipeline 4 converge in the gas-water main pipe 2, and the first pressure gauge 5 is arranged at the confluence; the natural gas pipeline 3 and the formation water pipeline 4 are both provided with a pressure pump 15; the gas-water main pipe 2, the natural gas pipeline 3 and the formation water pipeline 4 are all provided with valves.

[0056] In the embodiment of the present invention, a back pressure pump 9 and a second pressure gauge 10 are provided on the first pipeline 7 to facilitate the recovery and storage of gas and water injected into the three-dimensional core model 1 . A valve is provided on the first pipeline 7 .

[0057] In the embodiment of the present invention, the camera 13 is signal-connected to the computer 14, so as to take pictures and videos of the camera 13 in real time, and monitor the injection and production seepage characteristics of natural gas after entering the three-dimensional core model 1, and store and process them.

[0058] In some other embodiments of the present invention, the natural gas pipeline 3 and the formation water pipeline 4 also converge into a third pipeline 16. The third pipeline 16 is configured to adapt to the recovery line in a simultaneous injection and simultaneous production simulation scenario (flowing from the natural gas pipeline 3 and the formation water pipeline 4 through the third pipeline 16 into the recovery container 8, i.e., the recovery line); a valve is provided on the third pipeline 16.

[0059] The specific operation method of the experimental device (one injection and one extraction scenario) in the embodiment of the present invention is as follows:

[0060] a. Perform high-resolution CT scanning on the actual reservoir core to be evaluated and create a three-dimensional digital core. Figure 2 , and obtain a three-dimensional pore network;

[0061] b. Describe the fracture-cavity morphology of the reservoir traced by the seismic ant body, or the fracture-cavity morphology of the fracture-cavity reservoir outcrop;

[0062] c. The fracture-cavity morphology after characterization is digitized using digital core software or MATLAB program to generate a data volume, and inserted into the three-dimensional pore network in step a to finally form a three-dimensional digital core model of the pore-cavity-fracture triple medium;

[0063] The pores of the model are generated based on the real core matrix pores, and the fracture-cavity structure is also described based on the fracture-cavity morphology in the real reservoir. Therefore, the model can reflect the real fracture-cavity reservoir to a great extent, so that the experiment using this model can more realistically simulate the seepage characteristics of underground fluids.

[0064] d. After the fracture and hole structure is inserted, the three-dimensional pore network model is enlarged proportionally. In order to observe the state of the fluid in the pores and cracks more clearly, it can be enlarged proportionally to the preset specifications;

[0065] e. Using 3D printing technology or casting technology to make a three-dimensional model of holes and cracks, using transparent visual materials as the making material, and the hardness and other properties of the material can be selected according to the rock physical properties of the reservoir, and finally obtaining a three-dimensional core model 1;

[0066] f. Wrap the outer periphery of the three-dimensional core model 1 in step e with a transparent shell, insert a plurality of cannulas, and then connect it to the experimental device (wherein the cannulas without external pipes are plugged with sealing plugs), connect the second pipeline 11 where the vacuum pump 12 is located, use the vacuum pump 12 to evacuate the experimental device for 24 hours, or keep the vacuum state at a constant pressure for 24 hours, check and confirm the sealing of the three-dimensional core model 1; then turn off the vacuum pump 12, close the valve on the second pipeline 11, and then connect the first pipeline 7 where the back pressure pump 9 is located;

[0067] g. Open the valves on the gas-water main 2, the natural gas pipeline 3 and the formation water pipeline 4, inject the dyed natural gas into the three-dimensional core model 1 through the natural gas pipeline 3, the formation water pipeline 4 and the gas-water main 2, control the injection speed of the gas and water through the pressure pump 15 interlocked with the flow meter 6, and monitor the pressure on the gas-water main 2 through the first pressure gauge 5;

[0068] h. During the experiment, a camera 13 (such as a high-definition camera) is used to take real-time photos and videos of the three-dimensional core model 1 to monitor the injection and production seepage characteristics of natural gas after it enters the three-dimensional core model 1.

[0069] The specific operation method of the experimental device (same injection and same extraction scenario) in the embodiment of the present invention is as follows:

[0070] Steps a, b, c, d, e, and f in the same injection-one-collection scenario;

[0071] g. When injecting gas, open the valves on the gas-water main 2, the natural gas pipeline 3, and the formation water pipeline 4, close the valve on the third pipeline 16, and inject the dyed natural gas into the three-dimensional core model 1 through the natural gas pipeline 3, the formation water pipeline 4, and the gas-water main 2. The injection speed of gas and water is controlled by the pressure pump 15 interlocked with the flow meter 6, and the pressure on the gas-water main 2 is monitored by the first pressure gauge 5; when extracting gas, close the valves on the natural gas pipeline 3 and the formation water pipeline 4, open the valve on the third pipeline 16, and extract gas, so the gas is injected and extracted from the same well;

[0072] h. During the experiment, a camera 13 (such as a high-definition camera) is used to take real-time photos and videos of the three-dimensional core model 1 to monitor the injection and production seepage characteristics of natural gas after it enters the three-dimensional core model 1.

[0073] The specific operation method of the experimental device in the embodiment of the present invention (multiple injection and multiple production scenario, at this time, the number of the cannula 1.1 on the three-dimensional core model 1 is greater than three, wherein more than one cannula 1.1 is used for gas injection, and more than one cannula 1.1 is used for gas production) is as follows:

[0074] Steps a, b, c, d, e in the same injection and extraction scenario;

[0075] f. Wrap the outer periphery of the three-dimensional core model 1 in step e with a transparent shell, insert a plurality of cannulas, and then connect it to the experimental device (wherein, a plurality of gas-water main pipes 2 are provided, the number of which is equal to the number of cannulas 1.1 for gas injection, a plurality of groups of natural gas pipelines 3 and formation water pipelines 4 are provided, the number of which is equal to the number of cannulas 1.1 for gas injection, such as 3, that is, there are 3 groups of natural gas pipelines 3 and formation water pipelines 4, each group of natural gas pipelines 3 and formation water pipelines 4 converges into one of the gas-water main pipes 2, and each group of natural gas pipelines 3 and formation water pipelines 4 is provided with a first pressure gauge 5 at the confluence of all gas-water main pipes 2 is provided with a first pressure gauge 5, all the natural gas pipelines 3 and the formation water pipelines 4 are provided with pressure pumps 15, all the gas-water main pipes 2, natural gas pipelines 3 and formation water pipelines 4 are provided with valves, and at the same time, a plurality of third pipelines 16 are provided, and the number of the third pipelines 16 is equal to the number of the intubation tubes 1.1 used for gas production), the second pipeline 11 where the vacuum pump 12 is located is connected, and the vacuum pump 12 is used to evacuate the experimental device for 24 hours, or keep the pressure constant in the vacuum state for 24 hours, and check and determine the sealing of the three-dimensional core model 1; then turn off the vacuum pump 12, close the valve on the second pipeline 11, and then connect the first pipeline 7 where the back pressure pump 9 is located;

[0076] g. When injecting gas, open all valves on the gas-water main pipes 2, all natural gas pipelines 3 and all formation water pipelines 4, close all valves on the third pipeline 16, and simultaneously inject dyed natural gas into the three-dimensional core model 1 through multiple natural gas pipelines 3, formation water pipelines 4 and gas-water main pipes 2, and interlock the pressure pumps 15 at each intersection with the flowmeter 6 on the gas-water main pipe 2 to control the injection speed of gas and water, and monitor the pressure on the corresponding gas-water main pipe 2 through each first pressure gauge 5; when extracting gas, close all valves on the natural gas pipelines 3 and formation water pipelines 4, open all valves on the third pipeline 16, and extract gas simultaneously to form multiple injection and multiple extraction of multiple wells;

[0077] h. During the experiment, a camera 13 (such as a high-definition camera) is used to take real-time photos and videos of the three-dimensional core model 1 to monitor the injection and production seepage characteristics of natural gas after it enters the three-dimensional core model 1.

[0078] In certain embodiments of the present invention, an experimental method for visually evaluating injection and production seepage characteristics of a fracture-cavity gas storage is provided, comprising:

[0079] first step:

[0080] A high-resolution CT scan is performed on the real reservoir core to be evaluated, and a digital model of the pore network is established. The reservoir fracture-cavity pattern obtained from seismic data or outcrop observation is then inserted into the established digital model of the pore network, thereby establishing a three-dimensional digital core model of the triple medium of pores, caves, and fractures. A three-dimensional core model is then made based on the digital core model1.

[0081] In practical applications, the higher the resolution of the CT scanner, the smaller the core pore structure is. Therefore, the final pore structure is very small, belonging to the millimeter-level core, and cannot scan the real reservoir fracture structure, so it cannot well reflect the fracture structure of the real reservoir core. In the established pore network digital model, inserting the reservoir fracture pattern obtained from seismic data or outcrop observations to establish a three-dimensional digital core model of pores, caves, and fractures can better solve the above problems. The prepared digital core model can better reflect the real fracture pattern of the real reservoir core to be evaluated, and the experimental results are more reliable.

[0082] The specific operation method is:

[0083] a. Perform high-resolution CT scanning on the actual reservoir core to be evaluated and create a three-dimensional digital core. Figure 1 , and obtain a three-dimensional pore network digital model;

[0084] b. Describe the reservoir fracture morphology traced by the seismic ant body, such as Figure 2This is an image of seismic ant body tracking interpretation of fracture-cavity reservoirs. Figure 3 It is a rendering based on the image (cross-section depiction); or the fracture-cavity morphology of the fracture-cavity reservoir outcrop is depicted, refer to Figure 4-6 , Figure 4 This is a photo of the outcrop of the fracture-cavity reservoir. Figure 5 is based on Figure 4 The image depicting the morphology of the outcrop fractures and caves in the middle Figure 6 yes Figure 5 Depiction of outcrop fracture and cave morphology;

[0085] In this step, when outcrops appear in the real reservoir, the fracture-cavity morphology of the outcrops of the fracture-cavity type reservoir is selected for characterization; when no outcrops appear in the real reservoir, or the outcrops have been severely damaged, or the outcrops are not representative of the fractures and caves of the reservoir, the fracture-cavity morphology of the reservoir to be evaluated tracked by the seismic ant body is selected for characterization;

[0086] c. The fracture-cavity morphology after characterization is digitized using digital core software or MATLAB program to generate a data body, which is inserted into the three-dimensional pore network in step a to eventually form a three-dimensional digital core model of the pore-cavity-fracture triple medium.

[0087] The pores of the model are generated based on the real core matrix pores, and the fracture-cavity structure is also depicted based on the fracture-cavity morphology in the real reservoir. Therefore, the model can reflect the real fracture-cavity reservoir to the greatest extent, so that the experiment using this model can more realistically simulate the seepage characteristics of underground fluids.

[0088] Step 2:

[0089] According to the three-dimensional digital core model obtained in the first step, the model is proportionally enlarged according to preset specifications. In this embodiment, in order to more clearly observe the state of the fluid in the holes and cracks, it can be proportionally enlarged into a 1m high cylinder. Of course, it can also be enlarged to a suitable height as needed; then the three-dimensional model of holes and cracks is made by using 3D printing technology or casting technology. The making material uses transparent visualization material. The hardness and other properties of the material can be selected according to the rock physical properties of the reservoir, and finally a three-dimensional core model 1 is obtained.

[0090] Step 3:

[0091] The three-dimensional core model 1 prepared in the second step is wrapped with a transparent shell, and a plurality of plugs 1.1 are inserted into the experimental device (wherein the plugs 1.1 without external pipes are plugged with sealing plugs) to carry out a high-speed injection and production seepage experiment of a gas storage reservoir, wherein the experimental device is the experimental device for visual evaluation described in the above embodiment, such as Figure 1 As shown;

[0092] The three-dimensional core model 1 is first constructed by performing CT scanning on the real reservoir core to be evaluated to construct a pore network digital model; then the reservoir fracture-cavity pattern obtained from seismic data or outcrop observation is inserted into the pore network digital model to obtain a three-dimensional digital core model, and then the three-dimensional digital core model is made into a three-dimensional core model 1 through 3D printing technology or casting technology.

[0093] The experimental process based on the experimental device is as follows:

[0094] Ⅰ. Connect the vacuum pump 12 to the production end, and vacuum can be carried out for 24 hours, or constant pressure can be maintained in the vacuum state for 24 hours. At the same time, the sealing of the three-dimensional digital core model can be checked. Then, the vacuum pump 12 is turned off, the valve on the second pipeline 11 is closed, and the first pipeline 7 where the back pressure pump 9 is located is connected;

[0095] Ⅱ. Open the valves on the gas-water main pipe 2, the natural gas pipeline 3 and the formation water pipeline 4, and inject natural gas into the three-dimensional core model 1 through the natural gas pipeline 3, the formation water pipeline 4 and the gas-water main pipe 2. In order to facilitate the observation of the seepage path of natural gas during the experiment, colored gases such as chlorine and ozone are added to the pumped natural gas. The injection speed of gas and water is controlled by the pressure pump 15 provided on the gas-water main pipe 2 and the flow meter 6 interlocked, and the pressure on the gas-water main pipe 2 is monitored by the first pressure gauge 5;

[0096] In this step, the pumping speed of natural gas is controlled by interlocking the pressure pump 15 with the flow meter 6, so that the seepage characteristics of natural gas at different injection speeds can be studied.

[0097] III. During the experiment, a camera 13 (a high-definition camera (can be multiple)) is used to take real-time photos and videos to monitor the injection and production seepage characteristics.

[0098] Among them, the injection and production seepage characteristics are the seepage path of natural gas after entering the three-dimensional core model 1; the crossflow path and equilibrium time information of the fluid between the high-permeability fracture-cavity body and the low-permeability matrix during the injection and production process; and the deformation information of the fracture-cavity during the injection and production process.

[0099] The experimental device and method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage provided in the embodiments of the present invention are also applicable to the construction of gas storage in the Sichuan Basin, including highly heterogeneous carbonate gas reservoirs. They can provide a deeper and more vivid understanding of the laws and influences of the non-equilibrium special seepage characteristics of the fracture-cavity bodies of such gas reservoirs, and provide support for the design of gas storage schemes.

[0100] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage, characterized in that: It comprises a three-dimensional core model (1) and a camera (13) arranged around the three-dimensional core model (1); The outer periphery of the three-dimensional core model (1) is wrapped with a transparent shell, a plurality of insert pipes (1.1) are inserted into the three-dimensional core model (1), and the insert pipes (1.1) are connected to gas and water main pipes (2); The three-dimensional core model (1) is also connected to a first pipeline (7) and a second pipeline (11), wherein the first pipeline (7) is connected to a recovery container (8), and the second pipeline (11) is connected to a vacuum pump (12); The three-dimensional core model (1) is made of transparent material.

2. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 1 is characterized in that: The gas-water main pipe (2) is also connected to a natural gas pipeline (3) and a formation water pipeline (4); the natural gas pipeline (3) and the formation water pipeline (4) converge into the gas-water main pipe (2); and pressure pumps (15) are provided on the natural gas pipeline (3) and the formation water pipeline (4).

3. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 2 is characterized in that: The gas-water main pipe (2) is provided with a first pressure gauge (5) and a flow meter (6).

4. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 3 is characterized in that: The first pressure gauge (5) is arranged at the confluence of the natural gas pipeline (3) and the formation water pipeline (4).

5. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 4 is characterized in that: The natural gas pipeline (3) and the formation water pipeline (4) also converge into a third pipeline (16), and the confluence point is the first pressure gauge (5).

6. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 1 is characterized in that: The first pipeline (7) is provided with a back pressure pump (9) and a second pressure gauge (10).

7. The experimental device for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to any one of claims 1 to 6, characterized in that: The camera (13) is signal-connected to a computer (14).

8. An experimental method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage, characterized in that: The experimental method is implemented based on the experimental device described in any one of claims 1 to 7, including: Inserting a plurality of insert pipes (1.1) into a three-dimensional core model (1) made of a transparent material, wherein the insert pipes (1.1) are connected to a gas and water main pipe (2); A first pipeline (7) and a second pipeline (11) are connected on the three-dimensional core model (1), wherein the first pipeline (7) is connected to a recovery container (8), and the second pipeline (11) is connected to a vacuum pump (12); Conduct injection and production seepage experiments in gas storage; The camera (13) takes real-time photos and videos of the three-dimensional core model (1) to monitor the injection and production seepage characteristics of natural gas after it enters the three-dimensional core model (1).

9. The experimental method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 8, characterized in that: The three-dimensional core model (1) is manufactured by the following steps: Conduct CT scanning on the real reservoir core to be evaluated and construct a digital model of the pore network; Inserting the reservoir fracture-cavity pattern obtained from seismic data or outcrop observation into the pore network digital model to obtain a three-dimensional digital core model; The three-dimensional digital core model is manufactured into a three-dimensional core model (1) by 3D printing or casting.

10. The experimental method for visual evaluation of injection and production seepage characteristics of fracture-cavity gas storage according to claim 8 or 9, characterized in that: The injection and production seepage characteristics include the seepage path of the natural gas after it enters the three-dimensional model (1); the crossflow path and equilibrium time of the fluid between the high-permeability fracture-cavity body and the low-permeability matrix during the injection and production process; And the changes of fractures and holes during gas injection and production.

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