3D Visualization Physical Simulation Device and Method for Injection-Recovery Head Difference in Converting Oil Reservoir into Gas Storage

Abstract

The present invention discloses a three-dimensional visualization physical simulation device and method for injection-production elevation difference in the reconstruction of an oil reservoir into a gas storage reservoir, belonging to the technical field of reconstructing an oil reservoir into a gas storage reservoir. The steps of the method include S1: obtaining the basic data and reservoir physical property parameters of the reservoir construction area; S2: designing the parameters of the three-dimensional visualization physical simulation model according to the similarity criterion numbers; S3: fabricating the three-dimensional visualization physical simulation model; S4: saturating with oil and then carrying out the oil reservoir water flooding development process, and then converting to the simulated cyclic injection-production process; S5: fabricating the three-dimensional visualization physical simulation model according to the same method as in step S3, adjusting different injection-production elevation differences for experiments, recording the positions of the oil-gas interfaces and the oil production volumes after the injection-production is completed, and calculating the gas cap index and the recovery factor. The method of the present invention can study the influence degree of different injection-production elevation differences on the gas cap index and the recovery factor of the reconstruction of an oil reservoir into a gas storage reservoir, and provides an experimental reference for the optimization of the perforation parameters of the injection-production wells in the reconstruction of an oil reservoir into a gas storage reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of converting oil reservoirs into gas storage reservoirs, and in particular to a three-dimensional visualization physical simulation device and method for the injection-production elevation difference in converting oil reservoirs into gas storage reservoirs. Background Technique

[0002] Underground gas storage reservoirs are an economical and effective means to ensure seasonal peak shaving and stable gas supply (natural gas). Gas reservoir types account for the majority of underground gas storage reservoirs, accounting for 75% of the total reservoir capacity, while oil reservoir-type gas storage reservoirs only account for 6% of the total reservoir capacity. There is great potential in converting depleted oil reservoirs into gas storage reservoirs. Developing oil reservoir-type gas storage reservoirs is of great significance for expanding the total reservoir capacity of gas storage reservoirs and stabilizing natural gas supply.

[0003] In the process of converting an oil reservoir into a gas storage reservoir, the setting of injection-production parameters is particularly important, including the setting of the vertical perforation elevation difference between the injection well and the production well (abbreviated as "injection-production elevation difference"). Relevant literature shows that the magnitude of the injection-production elevation difference can significantly affect the gas drive sweep efficiency of the gas storage reservoir, the distribution of reservoir fluids, the positions of the oil-gas interface and the oil-water interface, and the injection-production gas capacity of the gas storage reservoir. A reasonable setting of the injection-production elevation difference can use the gravity segregation effect to inhibit water invasion, improve the gas drive sweep efficiency, thereby improving the utilization efficiency of the reservoir space for building the gas storage reservoir, and ensuring the coordinated progress of building the gas storage reservoir and improving the recovery rate.

[0004] At present, the optimization of injection-production parameters for gas storage reservoirs mainly relies on numerical simulation technology, but numerical models are difficult to truly reflect complex seepage mechanisms such as gravity segregation caused by different injection-production elevation differences. Existing physical simulation devices mostly focus on conventional gas drive development and lack the multi-dimensional regulation and visualization observation functions for the injection-production elevation difference. Therefore, there is an urgent need for a method to comprehensively evaluate the influence law of different injection-production elevation differences on the dynamic characteristics of converting oil reservoirs into gas storage reservoirs, which is convenient for targeted dynamic adjustment of injection-production process parameters in practical applications, maximizing the utilization efficiency of the reservoir space and ensuring the long-term stable operation of the gas storage reservoir. Summary of the Invention

[0005] Aiming at the problem that the existing physical simulation devices for gas storage reservoirs lack the multi-dimensional regulation and visualization observation functions for the injection-production elevation difference, the present invention provides a three-dimensional visualization physical simulation device and method for the injection-production elevation difference in converting oil reservoirs into gas storage reservoirs. It is applicable to the optimization of injection-production parameters for converting depleted oil reservoirs into gas storage reservoirs, the study of gas cap formation laws, and the evaluation of reservoir utilization effects.

[0006] The three-dimensional visualization physical simulation method for the injection-production elevation difference in converting an oil reservoir into a gas storage reservoir provided by the present invention includes the following steps:

[0007] S1: Obtain the basic data and reservoir physical property parameters of the reservoir building area, including parameters such as the length, width, reservoir thickness and dip angle, porosity, permeability, oil saturation and water saturation at the time of reservoir building of the actual oil reservoir.

[0008] S2: Design the parameters of the three-dimensional visual physical simulation model according to the similarity criterion group, including geometric similarity, physical property similarity, production performance similarity, and pressure similarity.

[0009] Geometric similarity includes the similarity of the ratio of reservoir length to width, the ratio of reservoir length to thickness, perforation position similarity, injection-production elevation difference similarity, characteristic length similarity, reservoir dip angle similarity, and gas cap index similarity.

[0010] The similarity of the ratio of reservoir length to width means that the ratio of the reservoir length to the width () of the three-dimensional visual physical simulation model is the same as that of the actual reservoir.

[0011] The similarity of the ratio of reservoir length to thickness means that the ratio of the reservoir length to the thickness () of the three-dimensional visual physical simulation model is the same as that of the actual reservoir.

[0012] Perforation position similarity means that the vertical elevation difference from the perforation of the high-position well to the top of the reservoir in the three-dimensional visual physical simulation model to the vertical elevation difference from the perforation of the low-position well to the top of the reservoir () is the same as that of the actual reservoir.

[0013] Injection-production elevation difference similarity means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir.

[0014] Characteristic length similarity means that the horizontal well spacing between the high-position well and the low-position well in the three-dimensional visual physical simulation model to the reservoir length () is the same as that of the actual reservoir.

[0015] Reservoir dip angle similarity and gas cap index similarity respectively mean that the reservoir dip angle , gas cap index m of the three-dimensional visual physical simulation model are the same as those of the actual reservoir. The gas cap index m refers to the ratio of the free gas volume to the pure oil volume under formation conditions, dimensionless.

[0016] Physical property similarity includes oil-water density similarity, oil-gas density similarity, oil-water mobility ratio similarity, oil-water saturation similarity at the time of reservoir formation, porosity similarity, and production degree similarity at the time of reservoir formation.

[0017] Oil-water density similarity and oil-gas density similarity respectively mean that the oil-phase density to the water-phase density The ratio of the density of the oil phase to the density of the gas phase is the same as that of the actual reservoir.

[0018] Similarity in oil-water mobility ratio means that the calculated value of the three-dimensional visual physical simulation model and are the relative permeabilities of the oil phase and the water phase, respectively; and are the viscosities of the oil phase and the water phase, respectively.

[0019] Similarity in oil-water saturation during reservoir construction means that the water saturation of the three-dimensional visual physical simulation model S w and the oil saturation S o have the same ratio as that of the actual reservoir.

[0020] Similarity in porosity means that the porosity of the three-dimensional visual physical simulation model is the same as that of the actual reservoir.

[0021] Similarity in production degree during reservoir construction means that the production degree during reservoir construction of the three-dimensional visual physical simulation model is the same as that of the actual reservoir.

[0022] Similarity in production performance includes similarity in oil production, water production, gas production, injection gas volume, and dimensionless time.

[0023] Similarity in oil production means that the calculated value of the three-dimensional visual physical simulation model

[0024] is the same as that of the actual reservoir; Similarity in water production means that the

[0025] calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir;

[0026] Similarity in gas production means that the calculated value of the three-dimensional visual physical simulation model

[0027] is the same as that of the actual reservoir; Similarity in dimensionless time means that the

[0028] In the formula: D is the wellbore diameter, m; K is the absolute permeability of the oil reservoir, mD; 、 、 are the relative permeabilities of the oil phase, water phase, and gas phase, dimensionless; is the production pressure differential, MPa; is the well perforation height, m; , , are the viscosities of the oil phase, water phase, and gas phase, mPa·s; , , are the production rates of the oil phase, water phase, and gas phase, m 3 / d; is the reservoir length, m; is the reservoir thickness, m; t is the production time, s; is the reservoir porosity, decimal; is the horizontal well spacing between the injection well and the production well, m.

[0029] Pressure similarity includes production pressure differential and gravity similarity, and production pressure differential and capillary force similarity.

[0030] Production pressure differential and gravity similarity means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir;

[0031] Production pressure differential and capillary force similarity means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir;

[0032] In the formula: is the production pressure differential, MPa; is the oil phase density, g / cm 3 ; is the acceleration of gravity, m / s 2 ; is the reservoir thickness, m; is the capillary pressure, MPa.

[0033] S3: Fabricate a three-dimensional visual physical simulation model and verify the airtightness of the model. Set a high-position well and a low-position well at different height positions of the three-dimensional visual physical simulation model, and install and connect various pipeline instruments and equipment to form a three-dimensional visual physical simulation experimental device.

[0034] The three-dimensional visual physical simulation model includes a base, on which a hydraulic jack and a support frame are installed. A simulation unit is installed at the top of the hydraulic jack and the support frame. The simulation unit is a rectangular box. After mixing quartz sand and an adhesive, the mixture is filled into the internal space of the box. A visual observation window made of a transparent material is arranged on one side of the box. A plurality of saturation electrodes and a pressure sensor are evenly distributed inside the box. The bottom surface of the box is hinged to the tops of the hydraulic jack and the support frame. By adjusting the hydraulic jack, the inclination angle of the box can be changed. A high-position well and a low-position well are respectively arranged at two different height positions on the top surface of the inclined box. After the adhesive in the box bonds and cures the quartz sand, the experiment can be carried out.

[0035] A camera device is arranged outside the visual observation window for observing and recording the position of the oil-gas interface in the box in real time. Combining with the saturation electrodes built in the box, the position of the oil-gas interface can be accurately determined.

[0036] The saturation electrodes and the pressure sensor are connected to an external computer processing device. After being processed by the computer, the pressure and gas distribution in the three-dimensional physical simulation device can be accurately detected.

[0037] The three-dimensional visual physical simulation model is placed in a large vertical oven to simulate the actual reservoir temperature, so as to carry out the experiment at the formation temperature subsequently.

[0038] S4: Inject simulated oil through the high-position well and saturate it, then inject water through the low-position well and produce oil through the high-position well to simulate the water flooding development process of the reservoir. After the water flooding development process of the reservoir ends, adjust to inject natural gas through the high-position well and use the low-position well as the production well to simulate the cyclic injection and production process of converting the reservoir into a gas storage reservoir. Among them, there is no production during the gas injection stage, and the time ratio of the gas injection stage to the production stage is set to 2:1.

[0039] S5: Make a three-dimensional visual physical simulation model according to the same method as in step S3, adjust the injection-production height difference between the high-position well and the low-position well to ensure that other conditions except the injection-production height difference are the same, then carry out the experiment according to the method in step S4, record the position of the oil-gas interface and the oil production volume after injection and production, and calculate the gas cap index based on the position of the oil-gas interface m , and calculate the recovery rate during the collaborative gas storage construction stage based on the oil production volume.

[0040] Each time a three-dimensional visual physical simulation model is made, it is necessary to ensure that the mesh number of the filled quartz sand is the same, the overburden pressure of the sand filling and the action time of the overburden pressure are the same, and the physical property parameters of each made model are ensured to be the same to the greatest extent, and the injection-production height difference is ensured to be a single variable. The injection-production height difference refers to the vertical height difference of the perforations between the high-position well and the low-position well.

[0041] Gas cap index m The calculation formula is as follows:

[0042]

[0043] In the formula: is the gas volume under formation conditions, m 3 ; is the oil volume under formation conditions, m 3 .

[0044] The device adopted by the above three-dimensional visualization physical simulation method for the injection-production elevation difference in the reservoir reconstruction for gas storage is a three-dimensional visualization physical simulation experimental device, and its structure includes a displacement pump, an intermediate container I, an intermediate container II, an intermediate container III, a three-dimensional visualization physical simulation model, an oven, a gas cylinder, an oil-gas-water separation device, a gas flowmeter, a gas recovery container, an oil metering device and a water metering device.

[0045] The intermediate container I, the intermediate container II and the intermediate container III are respectively used to store simulated oil, formation water and simulated gas. The bottom input ends of the three intermediate containers are connected to the displacement pump through a four-way interface I, and valves are provided in each parallel pipeline; the intermediate container III is connected to the gas cylinder through a three-way interface I to provide sufficient gas source. The other end of the three-way interface I is sequentially connected to a valve IV and one end of a three-way interface II. The other end of the three-way interface II is connected to the top output end of the intermediate container I. The remaining end of the three-way interface II is sequentially connected to a valve V, a pressure gauge I and one end of a three-way interface III. The other port of the three-way interface III is connected to the high-position well of the three-dimensional visualization physical simulation model. The remaining port of the three-way interface III is sequentially connected to a valve VIII, a three-way interface V and the oil-gas-water separation device; the top output end of the intermediate container II is sequentially connected to a valve VI, a pressure gauge II, one end of a three-way interface IV, the other end of the three-way interface IV is connected to the low-position well of the three-dimensional visualization physical simulation model, and the remaining end of the three-way interface IV is sequentially connected to a valve VII, a three-way interface V and the oil-gas-water separation device; the side wall of the oil-gas-water separation device is provided with a gas phase outlet, an oil phase outlet and a water phase outlet from top to bottom. The gas phase outlet is connected to the gas flowmeter and the gas recovery container, and the oil phase outlet and the water phase outlet are respectively connected to the oil metering device and the water metering device. The three-dimensional visualization physical simulation model is placed in the oven to simulate the actual reservoir temperature.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The present invention takes into account the influence of the injection-production elevation difference on the gas cap size and the ultimate oil recovery rate of the reservoir reconstruction for gas storage, and for the first time proposes to correspond the parameters of the actual model with those of the laboratory three-dimensional visualization reservoir reconstruction for gas storage model based on the similarity criterion, which can provide an experimental basis for the design and optimization of the perforation parameters of the gas storage reservoir, so as to dynamically adjust the perforation parameters of the injection-production wells at different production stages, thereby ensuring the efficient and stable operation of the gas storage reservoir.

[0048] In addition to being used for studying the influence of the injection-production elevation difference in the reservoir converted into a gas storage reservoir, the present invention can also be popularized and applied in other engineering fields such as the reservoir converted into a gas storage reservoir of other types like depleted gas reservoirs and aquifers, and the cyclic gas injection gravity drive in the reservoir, etc., which has wide application value.

[0049] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0050] Figure 1 It is a schematic structural diagram of a three-dimensional visualization physical simulation experimental device for the injection-production elevation difference in the reservoir converted into a gas storage reservoir provided by the present invention.

[0051] Figure 2 It is a curve graph of the relationship between the injection-production elevation difference and the cumulative production degree obtained in this embodiment.

[0052] Figure 3 It is the injection-production elevation difference and the gas cap index obtained in this embodiment m Curve graph of the relationship

[0053] Reference numerals in the figure: 1 - ISCO pump, 2 - gas cylinder, 3 - intermediate container III, 4 - intermediate container II, 5 - intermediate container I, 6 - valve III, 7 - valve II, 8 - valve I, 9 - four-way interface I, 10 - three-way interface I, 11 - valve IV, 12 - three-way interface II, 13 - valve V, 14 - valve VI, 15 - pressure gauge II, 16 - pressure gauge I, 17 - three-way interface III, 18 - simulation unit, 19 - hydraulic jack, 20 - support frame, 21 - base, 22 - camera device, 23 - three-way interface IV, 24 - valve VII, 25 - valve VIII, 26 - three-way interface V, 27 - oil-gas-water separation device, 28 - gas flowmeter, 29 - gas recovery container, 30 - water metering device, 31 - oil metering device, 32 - high-position well, 33 - low-position well, 34 - data processing device, 35 - saturation electrode, 36 - pressure sensor, 37 - oven, 38 - visual observation window. Detailed Embodiment

[0054] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0055] Such as Figure 1As shown in the figure, the three-dimensional visualization physical simulation experimental device for the injection-production elevation difference of the reservoir reconstructed into a gas storage reservoir provided by the present invention mainly comprises an ISCO pump 1 as a displacement pump, an intermediate container I 5, an intermediate container II 4, an intermediate container III 3, a three-dimensional visualization physical simulation model, an oven 37, a gas cylinder 2, an oil-gas-water separation device 27, a gas flowmeter 28, a gas recovery container 29, an oil metering device 31 and a water metering device 30.

[0056] The three-dimensional visualization physical simulation model comprises a base 21. A hydraulic jack 19 and a support frame 20 are installed on the base 21. A cuboid-shaped simulation unit 18 is installed at the tops of the hydraulic jack 19 and the support frame 20. The simulation unit 18 is made by filling and cementing quartz sand in a rectangular box body. Specifically, quartz sand and an adhesive are mixed and filled in the internal space of the box body. A visual observation window 38 made of a transparent material is arranged on one side surface of the box body. A plurality of saturation electrodes 35 and a pressure sensor 36 are evenly distributed inside the box body. The saturation electrodes 35 are used to monitor the oil-gas saturation. The bottom surface of the box body is hinged to the tops of the hydraulic jack 19 and the support frame 20. The height of the support frame 20 remains unchanged. By adjusting the support height of the hydraulic jack 19, the inclination angle of the box body is changed. A high-position well 32 and a low-position well 33 are respectively arranged at two different height positions on the top surface of the inclined box body. The high-position well 32 and the low-position well 33 are used to simulate injection wells or production wells. After the adhesive in the box body bonds and cures the quartz sand, the experiment can be carried out. The three-dimensional visualization physical simulation model is placed in a large vertical oven 37 to simulate the actual reservoir temperature. A visual observation window is also arranged on one side wall surface of the oven 37, which is arranged opposite to the visual observation window 38. A camera device 22 is installed at a position outside the oven opposite to the visual observation window to observe and record the position of the oil-gas interface in the box body during the experiment in real time. Combining with the saturation electrodes built in the box body, the position of the oil-gas interface can be accurately determined.

[0057] The intermediate container 1-5, intermediate container 2-4, and intermediate container 3-3 are respectively used to store simulated oil, formation water, and simulated gas (natural gas). The bottom input ends of the three intermediate containers are connected to the ISCO pump 1 through a four-way interface 1-9. Valves are provided in each parallel pipeline, namely valve 1-8, valve 2-7, and valve 3-6. The intermediate container 3-3 is connected to the gas cylinder 2 through a three-way interface 1-10. The same simulated gas is stored in the gas cylinder 2 and the intermediate container 3-3. The gas cylinder 2 is used as a backup to provide sufficient gas source. The other end of the three-way interface 1-10 is sequentially connected to the valve 4-11 and one end of the three-way interface 2-12. The other end of the three-way interface 2-12 is connected to the top output end of the intermediate container 1-5. The remaining end of the three-way interface 2-12 is sequentially connected to the valve 5-13, pressure gauge 1-16, and one end of the three-way interface 3-17. The other port of the three-way interface 3-17 is connected to the high-position well 3-32 of the three-dimensional visual physical simulation model. The remaining port of the three-way interface 3-17 is sequentially connected to the valve 8-25, three-way interface 5-26, and the oil-gas-water separation device 2-27. The top output end of the intermediate container 2-4 is sequentially connected to the valve 6-14, pressure gauge 2-15, one end of the three-way interface 4-23, and the other end of the three-way interface 4-23 is connected to the low-position well 3-33 of the three-dimensional visual physical simulation model. The remaining end of the three-way interface 4-23 is sequentially connected to the valve 7-24, three-way interface 5-26, and the oil-gas-water separation device 2-27. The side wall of the oil-gas-water separation device 2-27 is provided with a gas-phase outlet, an oil-phase outlet, and a water-phase outlet from top to bottom. The gas-phase outlet is connected to the gas flow meter 2-28 and the gas recovery container 2-29. The oil-phase outlet and the water-phase outlet are respectively connected to the oil metering device 3-31 and the water metering device 3-30. The oil metering device 3-31 and the water metering device 3-30 are both containers with volume scales, and the liquid volume in the container can be directly read. The oil-gas-water separation device 2-27 is specifically a sealed barrel-shaped container. The oil, gas, and water mixture is automatically separated in the barrel-shaped container. The gas is located at the top of the container, and the water is located at the bottom of the container. The density of the oil is lower than that of the water, and the oil is located above the water.

[0058] In a specific embodiment, eight saturation electrodes 3-35 and a pressure sensor 3-36 are uniformly arranged during the sand filling of the three-dimensional visual physical simulation model. The data obtained by the saturation electrodes 3-35 and the pressure sensor 3-36 are transmitted to an external data processing device 3-34, and then the pressure and gas distribution in the three-dimensional physical simulation device can be accurately detected.

[0059] Taking a certain oil reservoir as an example, the influence of the injection-production height difference on the conversion of the oil reservoir into a gas storage reservoir is studied by using the injection-production height difference three-dimensional visual physical simulation device and method of the present invention for the conversion of the oil reservoir into a gas storage reservoir, and a reasonable injection-production height difference for the conversion of the oil reservoir into a gas storage reservoir is determined. The specific steps are as follows:

[0060] (1)Obtain the basic data and reservoir physical property parameters during reservoir construction in the reservoir construction area, including the length, width, reservoir thickness and dip angle, porosity, permeability, oil saturation and water saturation during reservoir construction, etc. The specific data is shown in Table 1.

[0061] Table 1 Basic data and reservoir physical property parameters during reservoir construction in the reservoir construction area

[0062]

[0063] (2)Design the parameters of the three-dimensional physical simulation experimental device according to the similarity criterion numbers, including length, width, height, production pressure difference, characteristic length, etc. At the same time, restricted by objective factors such as experimental conditions, model scale, and human factors, it is difficult to process all reservoir physical property parameters completely according to the similarity criterion. Considering the rationality of model parameters and the actual situation, some model parameters were appropriately optimized and adjusted to obtain the parameters of the three-dimensional visual physical simulation model shown in Table 2.

[0064] Table 2 Parameters of the three-dimensional visual physical simulation model designed according to the similarity criterion

[0065]

[0066] (3)Fabricate a three-dimensional visual physical model by the sand filling and cementing method and verify the airtightness of the model. Connect and debug various pipeline instruments and equipment to obtain Figure 1 the three-dimensional visual physical simulation experimental device for the injection-production elevation difference of the reservoir reconstruction into a gas storage reservoir shown.

[0067] During the process of fabricating the three-dimensional visual physical model, 60-mesh quartz sand is mixed with an adhesive and evenly filled into the rectangular box body, and appropriate overburden pressure is used for compaction to ensure that the porosity and permeability parameters of the model are consistent with the actual formation. Set one injection well and one production well (well 32 at the high position and well 33 at the low position) according to the well spacing of 0.78 m and the injection-production elevation difference in the horizontal direction. The diameters of the injection and production wells are both 0.005 m, and the perforation section lengths are both 0.01 m. After the model is completely cemented, connect other pipeline equipment, and set the inclination angle of the rectangular box body to 15° through the hydraulic jack 19; then place the three-dimensional visual physical model in a large vertical oven 37, and set the oven temperature to 75 °C. Open valve 8, valve 13, and valve 24, keep other valves closed, start the ISCO pump 1, and pump simulated oil into the simulation unit 18 at a speed of 20 mL / min to verify the model tightness and saturate the simulation unit with simulated oil at the same time. Calculate the total saturated oil of 5974.9 mL through the difference between the pumped-in volume and the produced volume.

[0068] (4)Simulate the water flooding development process of the oil reservoir;

[0069] Close valve 1, valve 5, and valve 7, and turn off ISCO pump 1; open valve 2, valve 6, and valve 8, start ISCO pump 1, and inject water into the simulation unit 18 at a rate of 10 mL / min for water flooding. Stop water flooding when 1275 mL of oil is collected from the oil metering device 31, reaching a production level of 21.34% at the time of reservoir construction.

[0070] (5)Simulate the construction and operation stage of the gas storage reservoir by cyclic gas injection and production;

[0071] Close valve 2, valve 6, and valve 8, and turn off ISCO pump 1; open valve 4 and valve 5, start ISCO pump 1, and inject gas at a rate of 0.65 mL / min. No production occurs during the gas injection stage, and the gas injection duration is 2 hours, simulating an 8-month gas injection period for the gas storage reservoir; after gas injection is completed, turn off ISCO pump 1, close valve 4 and valve 5, open valve 7, adjust valve 7 through the reading of the gas flow meter 28, control the gas production rate to 1.3 mL / min, and the production duration is 1 hour, simulating a 4-month gas production period for the gas storage reservoir. Record the oil, gas, and water production through the oil and water metering devices, and record the position of the oil-gas interface after each cycle through the saturation electrode 35 and the imaging device 22 to calculate the gas cap index; repeat this cycle 6 times for the co-construction stage of the gas storage reservoir.

[0072] (6)Conduct experiments by changing different injection-production height differences;

[0073] Remake the three-dimensional visualization physical model, set the injection-production height differences to 0.01 m, 0.02 m, 0.03 m, 0.04 m, and 0.05 m, corresponding to the actual injection-production height differences of 10 m, 30 m, 50 m, 70 m, and 90 m respectively, with other experimental conditions remaining unchanged. The experimental steps are as described above. The experimental results of five groups with different injection-production height differences for six cycles are shown in Table 3. The oil recovery results for different injection-production height differences after cyclic injection and production are as Figure 2 shown, and the gas cap index results are as Figure 3 shown. Figure 2 and Figure 3 In the abscissa of

[0074] Table 3 Experimental results after cyclic injection and production with different injection-production height differences

[0075]

[0076] In summary, the simulation method of the present invention takes into account the influence of the injection-production height difference on the gas cap index and the production level, and can evaluate the influence of the injection-production height difference on the operation of the gas storage reservoir, thus providing an experimental basis for optimizing the perforation parameters of the injection-production wells.

[0077] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the technical content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A three-dimensional visualization physical simulation method for the injection-production elevation difference in the conversion of an oil reservoir into a gas storage reservoir, characterized in that, It includes the following steps: S1: Obtain the basic data of the reservoir building area and reservoir physical property parameters; S2: Design the parameters of the three-dimensional visual physical simulation model according to the similarity criterion groups, including geometric similarity, physical property similarity, production performance similarity, and pressure similarity; S3: Fabricate the three-dimensional visual physical simulation model and verify the airtightness of the model. Install a high-position well and a low-position well at different height positions of the three-dimensional visual physical simulation model, and install and connect various pipeline instruments and equipment to form a three-dimensional visual physical simulation experimental device; The three-dimensional visual physical simulation model includes a base. A hydraulic jack and a support frame are installed on the base. The top of the hydraulic jack and the support frame is installed with a simulation unit. The simulation unit is a rectangular box. After mixing quartz sand and adhesive, it is filled into the internal space of the box. A visual observation window made of transparent material is provided on one side of the box. A plurality of saturation electrodes and a pressure sensor are evenly distributed inside the box; The bottom surface of the box is hinged to the top of the hydraulic jack and the support frame. By adjusting the hydraulic jack, the inclination angle of the box can be changed. A high-position well and a low-position well are respectively arranged at two different height positions on the top surface of the inclined box. After the adhesive in the box bonds and cures the quartz sand, the experiment can be carried out; S4: Inject simulated oil through the high-position well and saturate it, then inject water from the low-position well, and produce oil from the high-position well to simulate the water flooding development process of the oil reservoir; After the water flooding development process of the oil reservoir is completed, adjust to inject natural gas from the high-position well and use the low-position well as the production well to simulate the cyclic injection and production process of converting the oil reservoir into a gas storage reservoir; S5: Fabricate a three-dimensional visual physical simulation model in the same way as in step S3, adjust the injection-production height difference between the high-position well and the low-position well, ensure that other conditions except the injection-production height difference are the same, and then conduct experiments in the way of step S4, record the position of the oil-gas interface and the oil production volume after the injection-production ends, and calculate the gas-cap index based on the position of the oil-gas interface. m , calculate the recovery rate during the collaborative reservoir building stage based on the oil production volume; the injection-production height difference refers to the vertical perforation height difference between the high-position well and the low-position well.

2. The three-dimensional visualization physical simulation method for injection-production elevation difference in the reservoir reconstructed into a gas storage reservoir according to claim 1, wherein, The basic data of the reservoir building area and reservoir physical property parameters obtained in step S1 include the length, width, reservoir thickness and dip angle, porosity, permeability, oil saturation and water saturation at the time of reservoir building of the actual oil reservoir.

3. The three-dimensional visualization physical simulation method for injection-production elevation difference in the reservoir reconstructed into a gas storage reservoir according to claim 2, characterized in that, In step S2, geometric similarity includes similarity of the ratio of reservoir length to width, similarity of the ratio of reservoir length to thickness, similarity of perforation positions, similarity of injection-production elevation difference, similarity of characteristic length, similarity of reservoir dip angle, and similarity of gas cap index; The similarity of the ratio of the reservoir length to the width means that the ratio of the reservoir length to the width of the three-dimensional visual physical simulation model is the same as that of the actual reservoir; The similarity of the ratio of reservoir length to thickness means that the reservoir length of the three-dimensional visual physical simulation model is the same as the thickness and the ratio is the same as that of the actual reservoir; The similarity of perforation positions means that the vertical height difference from the perforation of the well at the high position in the three-dimensional visualization physical simulation model to the top of the reservoir is the same as that from the perforation of the well at the low position to the top of the reservoir; The ratio is the same as that of the actual reservoir. The similarity of injection-production elevation difference means that the calculated value is the same as that of the actual reservoir; The similarity of characteristic lengths means that the horizontal well spacing between the high-position well and the low-position well in the three-dimensional visual physical simulation model is the same as that of the reservoir length and the ratio is the same as that of the actual reservoir; Reservoir dip angle similarity and gas cap index similarity respectively refer to the reservoir dip angle of the three-dimensional visualization physical simulation model , gas cap index m being the same as that of the actual reservoir, and the gas cap index m refers to the ratio of the free gas volume to the pure oil volume under formation conditions.

4. The three-dimensional visualization physical simulation method for injection-production elevation difference in the reservoir reconstructed into a gas storage reservoir according to claim 2, wherein, In step S2, physical property similarity includes similarity of oil-water density, similarity of oil-gas density, similarity of oil-water mobility ratio, similarity of oil-water saturation at the time of reservoir building, similarity of porosity, and similarity of recovery factor at the time of reservoir building; The similarity of oil-water density and the similarity of oil-gas density respectively refer to the density of the oil phase in the three-dimensional visual physical simulation model and the density of the water phase The ratio of the density of the oil phase and the density of the gas phase is the same as that of the actual reservoir; The similarity of oil-water mobility ratio means that the calculated value is the same as that of the actual reservoir; among them, and are the relative permeabilities of the oil phase and the water phase respectively; and are the viscosities of the oil phase and the water phase respectively; When building the reservoir model, the similarity of oil-water saturation means that the water saturation of the three-dimensional visualization physical simulation model S w is the same as the oil saturation S o and their ratio is the same as that of the actual reservoir; Porosity similarity means that the porosity of the three-dimensional visual physical simulation model is the same as that of the actual reservoir; The recovery factor at the time of building the reservoir being similar means the recovery factor at the time of building the 3D visual physical simulation model is the same as that of the actual reservoir.

5. The three-dimensional visualization physical simulation method for injection-production elevation difference in the reservoir reconstructed into a gas storage reservoir according to claim 2, wherein, In step S2, production performance similarity includes similarity of oil production, similarity of water production, similarity of gas production, similarity of injection gas volume, and similarity of dimensionless time; Similar oil production means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir; Similar water production means that the calculated value of the three-dimensional visualization physical simulation model is the same as that of the actual reservoir; Similar gas production means that the calculated value of the 3D visual physical simulation model is the same as that of the actual reservoir; Similar gas injection volume means that the calculated value of the 3D visual physical simulation model is the same as that of the actual reservoir; The dimensionless time similarity means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir; In the formula: D is the wellbore diameter, m; K is the absolute permeability of the oil reservoir, mD; , , are the relative permeabilities of the oil phase, water phase, and gas phase, dimensionless; is the production pressure differential, MPa; is the well perforation height, m; , , are the viscosities of the oil phase, water phase, and gas phase, mPa·s; , , are the production rates of the oil phase, water phase, and gas phase, m 3 / d; is the reservoir length, m; is the reservoir thickness, m; t is the production time, s; is the reservoir porosity, in decimals; is the horizontal well spacing between the injection well and the production well, m.

6. The three-dimensional visualization physical simulation method for injection-production elevation difference of a reservoir reconstructed into a gas storage reservoir according to claim 2, wherein In step S2, pressure similarity includes similarity of production pressure difference and gravity, and similarity of production pressure difference and capillary force; The similarity between the production pressure difference and gravity means that the calculated value of the three-dimensional visual physical simulation model is the same as that of the actual reservoir; The similarity between the production pressure differential and the capillary force means that the calculated value is the same as that of the actual reservoir; Where: is the production pressure differential, MPa; is the density of the oil phase, g / cm 3 ; is the acceleration due to gravity, m / s 2 ; is the reservoir thickness, m; is the capillary pressure, MPa.

7. A three-dimensional visualization physical simulation experimental device for implementing the method according to any one of claims 1-6, characterized in that, It includes a displacement pump, intermediate container 1, intermediate container 2, intermediate container 3, three-dimensional visual physical simulation model, oven, gas cylinder, oil-gas-water separation device, gas flowmeter, gas recovery container, oil metering device, and water metering device; The intermediate container 1, intermediate container 2, and intermediate container 3 are respectively used to store simulated oil, formation water, and simulated gas. The bottom input ends of the three intermediate containers are connected to a displacement pump through a four-way interface 1, and valves are provided in each parallel pipeline; the intermediate container 3 is connected to a gas cylinder through a three-way interface 1 to provide sufficient gas source. The other end of the three-way interface 1 is sequentially connected to a valve 4 and one end of a three-way interface 2. The other end of the three-way interface 2 is connected to the top output end of the intermediate container 1. The remaining end of the three-way interface 2 is sequentially connected to a valve 5, a pressure gauge 1, and one end of a three-way interface 3. The other port of the three-way interface 3 is connected to the high-position well of the three-dimensional visualization physical simulation model. The remaining port of the three-way interface 3 is sequentially connected to a valve 8, a three-way interface 5, and an oil-gas-water separation device; the top output end of the intermediate container 2 is sequentially connected to a valve 6, a pressure gauge 2, one end of a three-way interface 4, the other end of the three-way interface 4 is connected to the low-position well of the three-dimensional visualization physical simulation model, and the remaining end of the three-way interface 4 is sequentially connected to a valve 7, a three-way interface 5, and an oil-gas-water separation device; on the side wall of the oil-gas-water separation device, a gas phase outlet, an oil phase outlet, and a water phase outlet are sequentially arranged from top to bottom. The gas phase outlet is connected to a gas flow meter and a gas recovery container, and the oil phase outlet and the water phase outlet are respectively connected to an oil metering device and a water metering device; the three-dimensional visualization physical simulation model is placed in an oven to simulate the actual reservoir temperature.

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