Water injection profile evolution experiment system and experiment method based on distributed optical fiber strain sensing

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a distributed optical fiber strain sensing-based water injection profile evolution experimental system and experimental method.The distributed optical fiber strain sensing-based layered water injection well far wellbore zone interlayer fluid channeling monitoring experimental system constructed by the invention can simulate an interlayer fluid channeling phenomenon of a far wellbore zone; and the lower interlayer pressing process under the action of high-pressure water injection is really simulated. According to the experimental system, the strain change generated outside the wellbore when interlayer fluid channeling occurs in a far wellbore zone can be simulated more truly, the response characteristics and the response rule of the strain can be obtained, and theoretical and method support is provided for reservoir internal change analysis and measure decision making.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to an experimental system and method for water injection profile evolution based on distributed optical fiber strain sensing. Background Technology

[0002] Layered water injection is an important method for resolving inter-layer conflicts and improving oil recovery in water-driven oilfields. During layered water injection, differences in formation properties and varying injection pressures or volumes lead to different pressure distributions around the wellbore and within the reservoir. Even with packers used to isolate the injection zones, inter-layer flow can occur due to factors such as wellbore cement sheath failure or the separation of the intermediate spacer between two injection zones caused by high-pressure water injection. Inter-layer flow can lead to inaccurate measurement of cumulative water injection volumes in each layer, potentially introducing errors into reservoir dynamic analysis. Therefore, accurately determining the existence of inter-layer flow is crucial for reservoir engineers to better understand the effectiveness of waterflooding.

[0003] Near-wellbore interlayer flow is easily detected in the wellbore due to its small distance from the wellbore, and temperature or noise changes caused by the flow can usually be effectively identified using traditional temperature or noise logging. However, when interlayer flow is caused by the breaking of intermediate strata in the far-wellbore zone, traditional temperature or noise logging methods are insufficient for accurate identification.

[0004] To address the difficulty in identifying interlayer flow phenomena in the distant well zone, this application proposes an experimental system and method for monitoring interlayer flow in the distant well zone of stratified water injection wells based on distributed optical fiber strain sensing. This system aims to understand the response characteristics and laws of interlayer flow in the distant well zone from the perspective of mechanical changes, providing a theoretical basis for guiding on-site production analysis. Summary of the Invention

[0005] The purpose of this invention is to provide an experimental system and method for monitoring interlayer flow in the distal zone of stratified water injection wells based on distributed optical fiber strain sensing. Based on the established experimental system for monitoring interlayer flow in the distal zone of stratified water injection wells using distributed optical fiber strain sensing, this invention obtains the response characteristics and laws of interlayer flow in the distal zone through indoor experiments, providing a theoretical basis for guiding on-site production analysis.

[0006] The technical problem to be solved by the present invention is achieved by the following technical solution: an experimental system for water injection profile evolution based on distributed optical fiber strain sensing, including a reservoir simulation system, an injection and production simulation system and a strain measurement system; The reservoir simulation system includes a pressure-resistant sealed container and, from top to bottom, an upper reservoir, an upper partition, a partition, a lower partition, and a lower reservoir, which are arranged sequentially inside the pressure-resistant sealed container. A partition crack simulation device is provided above the lower partition plate. The partition crack simulation device is located inside the partition. An opening is provided on the lower partition plate. The partition crack simulation device includes a screen tube, a pressure spring provided inside the screen tube, and a sealing plate located at the lower end of the pressure spring. Screen holes are provided on the side wall of the screen tube. The screen tube is vertically positioned above the opening. The sealing plate is slidably installed inside the screen tube. An upper cover plate is provided at the upper end of the screen tube. The injection-production simulation system includes a water storage tank, a production wellbore, an upper reservoir injection pump, a lower reservoir injection pump, an outflow pipeline, a backpressure valve, and a return pipeline. The water storage tank is connected to the left end of the upper reservoir via the upper reservoir injection pump, and the water storage tank is connected to the left end of the lower reservoir via the lower reservoir injection pump. The right ends of the upper and lower reservoirs are respectively connected to the production wellbore via independent pipelines. The outlet of the production wellbore is connected to the backpressure valve via the outflow pipeline, and the backpressure valve is connected to the water storage tank via the return pipeline. The strain measurement system includes a steel-armored optical cable and a distributed fiber optic strain sensor demodulator. The steel-armored optical cable is vertically positioned on the left side of the pressure-resistant sealed container. It sequentially passes through the lower reservoir, lower partition, partition, upper partition, upper reservoir, and the top of the pressure-resistant sealed container before connecting to the distributed fiber optic strain sensor demodulator. This invention simulates multiple reservoirs using the upper reservoir, upper partition, partition, lower partition, and lower reservoir, and uses a partition fracture simulation device to simulate fractures. The steel-armored optical cable is vertically positioned at the left end of the pressure-resistant sealed container. Fluid is injected into the upper and lower reservoirs from the left side of the pressure-resistant sealed container, and fluid is collected from the right side of the pressure-resistant sealed container using the production wellbore. This simulates interlayer flow in the far-well zone. During the experiment, the steel-armored optical cable is used to measure strain changes during the stratified water injection process to obtain the response characteristics and response laws of interlayer flow in the far-well zone.

[0007] Preferably, the lower end of the screen tube is provided with a lower cover plate, and the lower cover plate is provided with screen holes. Providing a lower cover plate with screen holes at the lower end of the screen tube can limit the sealing sheet and effectively prevent sand particles in the partition from entering the interior of the screen tube.

[0008] Preferably, the cover plate of the present invention is provided with sieve holes.

[0009] Preferably, the pressure-resistant sealing container of the present invention includes an upper cover, a vertical frame, and a lower cover; The vertical frame is located between the upper cover and the lower cover, and the lower end face of the upper cover and the upper end face of the lower cover are respectively provided with limiting and sealing grooves that match the vertical frame; The upper and lower covers are fixedly connected by screws. The upper and lower ends of the vertical frame are directly inserted into the limiting and sealing grooves of the upper and lower covers, and the upper and lower covers are connected together by screws, which realizes the assembly and sealing of the pressure-resistant sealing container. The structure is simple.

[0010] Preferably, the vertical frame of the present invention includes a left side cover, a right side cover, a front side plate, and a rear side plate; The left and right covers are arranged opposite to each other. The left cover has two injection holes and the right cover has two outflow holes. The front and rear side panels are arranged opposite each other.

[0011] Preferably, the present invention further includes a lower reservoir injection channel, an upper reservoir injection channel, an upper reservoir outflow channel, and a lower reservoir outflow channel; The lower reservoir injection channel and the upper reservoir injection channel are respectively located in the injection hole; The upper and lower reservoir outflow channels are respectively located within the outflow orifice. The lower and upper reservoir injection channels are located within the injection orifice to facilitate the connection of the upper and lower reservoir injection pumps to these channels via pipelines. Similarly, the upper and lower reservoir outflow channels are located within the outflow orifice to facilitate the connection of the production wellbore to the pressure-resistant sealing container.

[0012] Preferably, the upper reservoir, interlayer, and lower reservoir of this invention are artificial cores formed by on-site cementation of resin and sand particles in a predetermined ratio. The upper reservoir, interlayer, and lower reservoir are prepared by mixing resin and sand particles together, simulating a rock core.

[0013] Preferably, the upper and lower reservoir injection pumps are variable frequency plunger pumps. The variable frequency plunger pumps provide different injection pressures and injection rates to the upper and lower reservoirs, respectively, to simulate the stratified water injection process.

[0014] This invention also discloses an experimental method for water injection profile evolution based on distributed optical fiber strain sensing. Utilizing the aforementioned experimental system for water injection profile evolution based on distributed optical fiber strain sensing, the method includes the following steps: S1. Prepare a reservoir simulation system and connect the injection-production simulation system and the strain measurement system to the reservoir simulation system; S2. Open the back pressure valve and use the upper reservoir injection pump and lower reservoir injection pump to send water of different flow rates into the upper and lower reservoirs respectively. The produced water returns to the water storage tank through the production well, outflow pipeline, back pressure valve and return pipeline, realizing the simulation of the layered water injection and combined layer mining process. S3. Close the back pressure valve to keep no fluid flowing out of the production wellbore. When the pressure of the lower reservoir is greater than the downward force of the lower spring, the sealing plate opens and water is injected into the interlayer to simulate interlayer flow in the far well zone. During the tests in steps S4, S2, and S3, the distributed fiber optic strain demodulator collects strain values ​​at various points along the vertical direction of the upper reservoir, interlayer, and lower reservoir in real time through the steel-armored optical cable. After the experiment is completed, the strain data collected by the distributed fiber optic strain sensor demodulator is exported, and the strain distribution along the vertical direction of the upper reservoir, interlayer, and lower reservoir is plotted.

[0015] In a preferred embodiment of the present invention, after the steel-armored optical cable and the distributed optical fiber strain sensor demodulator are connected in step S1, the distributed optical fiber strain sensor demodulator is started, and the measurement point is located by tapping the steel-armored optical cable at the top outlet of the pressure-resistant sealed container.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The experimental system for monitoring interlayer flow in the far well zone of the layered water injection well based on distributed optical fiber strain sensing constructed by the present invention can simulate the interlayer flow phenomenon in the far well zone and truly simulate the process of layer pressure opening under high pressure water injection.

[0017] (2) This invention utilizes distributed optical fiber strain sensing technology to monitor interlayer flow phenomena in remote well zones, providing a new monitoring method for studying internal reservoir flow.

[0018] (3) The experimental system for monitoring interlayer crossflow in the far zone of the stratified water injection well based on distributed optical fiber strain sensing of the present invention can more realistically simulate the strain changes generated outside the wellbore when interlayer crossflow occurs in the far zone, obtain the response characteristics and response laws of the strain, and provide theoretical and methodological support for analyzing changes inside the reservoir and making decision-making on measures. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to the present invention. Figure 2 This is a schematic diagram of the closed state of the crack in the interlayer crack simulation device. Figure 3 This is a schematic diagram of the crack opening state of the interlayer crack simulation device. Figure 4 This is a top view of the lower partition. Figure 5 for Figure 1 Top view of section AA; Figure 6 This is a schematic diagram of the upper cover structure; Figure 7 This is a schematic diagram of the lower cover structure; Figure 8 A schematic diagram of external strain in the wellbore where no interlayer flow occurred in the far-well zone of the two-layer water injection zone; Figure 9A schematic diagram of the wellbore outside showing the phenomenon of interlayer flow in the far-well zone of two water injection layers; In the figure, the components are: 1. Pressure-resistant sealed container; 2. Upper reservoir; 3. Upper partition; 4. Partition; 5. Lower partition; 6. Opening; 7. Lower reservoir; 7. Partition crack simulation device; 7. Screen tube; 71. Lower pressure spring; 72. Sealing plate; 73. Upper cover plate; 74. Lower cover plate; 75. 8. Water storage tank; 9. Production wellbore; 10. Upper reservoir injection pump; 11. Lower reservoir injection pump; 12. Outflow pipeline; 13. Back pressure valve; 14. Return liquid pipeline; 15. Steel armored optical cable; 16. Distributed optical fiber strain sensor demodulator. Upper cover 101, vertical frame 102, lower cover 103, limiting and sealing groove 100; Left side cover 1021, right side cover 1022, front side panel 1023, rear side panel 1024; Injection hole 10211, outflow hole 10221; Lower reservoir injection channel 17, upper reservoir injection channel 18, upper reservoir outflow channel 19, lower reservoir outflow channel 20. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] like Figure 1 and Figure 2 As shown, an experimental system for water injection profile evolution based on distributed optical fiber strain sensing includes a reservoir simulation system, an injection-production simulation system, and a strain measurement system.

[0022] The reservoir simulation system includes a pressure-resistant sealed container 1 and, from top to bottom, an upper reservoir 2, an upper partition 3, a partition 4, a lower partition 5, and a lower reservoir 6, which are arranged sequentially within the pressure-resistant sealed container 1. In this embodiment, the upper partition 3 and the lower partition 5 are rectangular impermeable steel plates.

[0023] like Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, a partition crack simulation device 7 is installed above the lower partition 5, located within the partition 4. The lower partition 5 has an opening 51. The partition crack simulation device 7 includes a screen tube 71, a pressure spring 72 installed within the screen tube 71, and a sealing plate 73 located at the lower end of the pressure spring 72. The sidewall of the screen tube 71 has screen holes. The screen tube 71 is vertically positioned above the opening 51. The sealing plate 73 is slidably installed within the screen tube 71. An upper cover plate 74 is installed at the upper end of the screen tube 71. The upper end of the pressure spring 72 is fixedly connected to the upper cover plate 74, and the other end is connected to the sealing plate 73. Under external force, the sealing plate 73 can move up and down within the screen tube 71 to simulate the partition being pressed open during water injection. The diameter of the sealing plate 73 is larger than the diameter of the opening 51. The lower end of the screen tube 71 is sealed to the lower partition 5.

[0024] The injection-production simulation system includes a water storage tank 8, a production wellbore 9, an upper reservoir injection pump 10, a lower reservoir injection pump 11, an outflow pipeline 12, a backpressure valve 13, and a return pipeline 14. The water storage tank 8 is connected to the left end of the upper reservoir 2 via the upper reservoir injection pump 10. The water storage tank 8 is connected to the left end of the lower reservoir 6 via the lower reservoir injection pump 11. The right ends of the upper reservoir 2 and the lower reservoir 6 are respectively connected to the production wellbore 9 via independent pipelines. The outlet of the production wellbore 9 is connected to the backpressure valve 13 via the outflow pipeline 12. The backpressure valve 13 is connected to the water storage tank 8 via the return pipeline 14.

[0025] The strain measurement system includes a steel-armored optical cable 15 and a distributed optical fiber strain sensor demodulator 16. The steel-armored optical cable 15 is vertically arranged on the left side of the pressure-resistant sealed container 1. The steel-armored optical cable 15 passes through the lower storage layer 6, the lower partition 5, the partition 4, the upper partition 3, the upper storage layer 2 and the top of the pressure-resistant sealed container 1 in sequence and is connected to the distributed optical fiber strain sensor demodulator 16.

[0026] The lower end of the sieve tube 71 is provided with a lower cover plate 75, and the lower cover plate 75 is provided with sieve holes.

[0027] The cover plate 74 is provided with sieve holes.

[0028] like Figure 1 As shown, the pressure-resistant sealed container 1 includes an upper cover 101, a vertical frame 102, and a lower cover 103.

[0029] The vertical frame 102 is located between the upper cover 101 and the lower cover 103, such as Figure 6 and Figure 7 As shown, the lower end face of the upper cover 101 and the upper end face of the lower cover 103 are respectively provided with limiting and sealing grooves 100 that match the vertical frame 102.

[0030] The upper cover 101 and the lower cover 103 are fixedly connected by screws, and a sealed cavity is formed between the vertical frame 102, the upper cover 101 and the lower cover 103.

[0031] like Figure 5 As shown, the vertical frame 102 includes a left cover 1021, a right cover 1022, a front panel 1023, and a rear panel 1024. The left cover 1021, the right cover 1022, the front panel 1023, and the rear panel 1024 have the same height.

[0032] The left cover 1021 and the right cover 1022 are arranged opposite to each other. The left cover 1021 is provided with two injection holes 10211, and the right cover 1022 is provided with two outflow holes 10221.

[0033] The front side panel 1023 and the rear side panel 1024 are arranged opposite to each other. The left side cover 1021, the right side cover 1022, the front side panel 1023 and the rear side panel 1024 form a rectangle.

[0034] The experimental system for water injection profile evolution based on distributed optical fiber strain sensing also includes a lower reservoir injection channel 17, an upper reservoir injection channel 18, an upper reservoir outflow channel 19, and a lower reservoir outflow channel 20.

[0035] The lower reservoir injection channel 17 and the upper reservoir injection channel 18 are respectively disposed in the injection hole 10211 and are used to connect the upper reservoir injection pump 10 and the lower reservoir injection pump 11.

[0036] The upper reservoir outflow channel 19 and the lower reservoir outflow channel 20 are respectively located in the outflow hole 10221 and are used to connect to the production wellbore 9.

[0037] The upper reservoir 2, the interlayer 4, and the lower reservoir 6 are artificial rock cores formed on-site by cementing resin and sand particles in a preset ratio.

[0038] The upper reservoir injection pump 10 and the lower reservoir injection pump 11 are variable frequency plunger pumps.

[0039] An experimental method for water injection profile evolution based on distributed fiber optic strain sensing, utilizing the aforementioned experimental system for water injection profile evolution based on distributed fiber optic strain sensing, includes the following steps: S1. Prepare a reservoir simulation system and connect the injection-production simulation system and the strain measurement system to the reservoir simulation system.

[0040] Specifically, first, the lower cover 103 is placed on a horizontal surface; then, the left cover 1021, right cover 1022, front plate 1023, and rear plate 1024 are vertically placed in the limiting sealing groove 100, and the four vertical steel plates are fastened with bolts to form the reservoir model cavity; third, the steel-armored optical cable 15 is vertically placed at a certain distance from the left cover 1021, and then a certain proportion of resin and sand mixture is poured into the cavity of the pressure-resistant sealing container 1 and compacted, with its height exceeding [a certain value]. The lower reservoir 6 is constructed at the height of the injection channel 17. Fourth, a hole is drilled in the lower partition 5, with the distance between the hole and the left cover 1021 being the same as the distance between the steel-armored optical cable 15 and the left cover 1021. The steel-armored optical cable 15 is passed through the hole, the lower partition 5 is placed above the lower reservoir 6, and the steel-armored optical cable 15 is fixed to the lower reservoir 6 with a clamp. Fifth, the assembled partition fracture simulation device 7 is placed directly above the opening 51, and the sealing plate 73 is tightened under the action of the downward spring 72. The resin and sand mixture is compacted around the opening 51 to form a hydraulic barrier with the lower partition 5; sixth, a certain proportion of resin and sand mixture is poured onto the lower partition 5 and compacted, with its height being less than the height of the upper reservoir injection channel 18, thus completing the construction of the partition 4; seventh, a hole is drilled in the upper partition 3, with the distance between the drilled hole and the left cover 1021 being the same as the distance between the steel armored optical cable 15 and the left cover 1021, and the steel armored optical cable 15 is passed through the drilled hole. The upper partition 3 is placed above the partition 4, and then the steel armored optical cable 15 is secured with a clamp. 5. Fix it to the upper partition 3; 8. Pour a certain proportion of resin and sand mixture onto the upper partition 3 and compact it until the height reaches the top of the left cover 1021; 9. Drill a hole in the upper cover 101, the distance between the hole and the left cover 1021 is the same as the distance between the steel armored optical cable 15 and the left cover 1021, and pass the steel armored optical cable 15 through the drilled hole; 10. Tighten the upper cover 101 and the lower cover 103 together with bolts, and fix the steel armored optical cable 15 to the upper cover 101 with a clamp.

[0041] S2. Open the back pressure valve 13 and use the upper reservoir injection pump 10 and the lower reservoir injection pump 11 to send water of different flow rates into the upper reservoir 2 and the lower reservoir 6 respectively. The produced water returns to the water storage tank 8 through the production wellbore 9, the outflow pipeline 12, the back pressure valve 13, and the return liquid pipeline 14, realizing the simulation of the layered water injection and combined layer mining process.

[0042] S3. Close the back pressure valve 13 to keep the production wellbore 9 free of fluid. When the pressure of the lower reservoir 6 is greater than the downward spring force of the lower spring 72, the sealing plate 73 opens and water is injected into the interlayer 4 to simulate interlayer flow in the far well zone.

[0043] During the tests in steps S4, S2, and S3, the distributed fiber optic strain demodulator 16 collects strain values ​​at various points along the vertical direction of the upper reservoir 2, interlayer 4, and lower reservoir 6 in real time through the steel-armored optical cable 15. After the experiment is completed, the strain data collected by the distributed fiber optic strain sensor demodulator 16 is exported, and the strain distribution along the vertical direction of the upper reservoir 2, interlayer 4, and lower reservoir 6 is plotted.

[0044] In the absence of interlayer flow in the far-well zone, under these experimental conditions, the compression spring 72 and sealing plate 73 in the interlayer fracture simulation device 7 are in a state of attachment. Figure 2 As shown, plot the strain distribution along the vertical direction of the upper reservoir 2, interlayer 4, and lower reservoir 6, as shown. Figure 8 As shown.

[0045] In the event of interlayer flow in the far-well zone, under these experimental conditions, the compression spring 72 and sealing plate 73 in the interlayer fracture simulation device 7 are in a state of attachment. Figure 3 As shown, plot the strain distribution along the vertical direction of the upper reservoir 2, interlayer 4, and lower reservoir 6, as shown. Figure 9 As shown.

[0046] In step S1, after the steel-armored optical cable 15 is connected to the distributed optical fiber strain sensor demodulator 16, the distributed optical fiber strain sensor demodulator 16 is started, and the measurement point is located by tapping the steel-armored optical cable 15 at the top outlet of the pressure-resistant sealed container 1.

Claims

1. An experimental system for water injection profile evolution based on distributed fiber optic strain sensing, characterized in that: This includes a reservoir simulation system, an injection-production simulation system, and a strain measurement system; The reservoir simulation system includes a pressure-resistant sealed container (1) and, from top to bottom, an upper reservoir (2), an upper partition (3), a partition (4), a lower partition (5), and a lower reservoir (6) arranged in the pressure-resistant sealed container (1). A partition crack simulation device (7) is provided above the lower partition (5). The partition crack simulation device (7) is located inside the partition (4). An opening (51) is provided on the lower partition (5). The partition crack simulation device (7) includes a screen tube (71), a pressure spring (72) provided inside the screen tube (71), and a sealing plate (73) located at the lower end of the pressure spring (72). The side wall of the screen tube (71) is provided with screen holes. The screen tube (71) is vertically positioned above the opening (51). The sealing plate (73) is slidably positioned inside the screen tube (71). An upper cover plate (74) is provided at the upper end of the screen tube (71). The injection-production simulation system includes a water storage tank (8), a production wellbore (9), an upper reservoir injection pump (10), a lower reservoir injection pump (11), an outflow pipeline (12), a back pressure valve (13), and a return pipeline (14). The water storage tank (8) is connected to the left end of the upper reservoir (2) through the upper reservoir injection pump (10). The water storage tank (8) is connected to the left end of the lower reservoir (6) through the lower reservoir injection pump (11). The right ends of the upper reservoir (2) and the lower reservoir (6) are respectively connected to the production wellbore (9) through independent pipelines. The outlet of the production wellbore (9) is connected to the back pressure valve (13) through the outflow pipeline (12). The back pressure valve (13) is connected to the water storage tank (8) through the return pipeline (14). The strain measurement system includes a steel-armored optical cable (15) and a distributed optical fiber strain sensor demodulator (16). The steel-armored optical cable (15) is vertically arranged on the left side of the pressure-resistant sealed container (1). The steel-armored optical cable (15) passes through the lower reservoir (6), the lower partition (5), the partition (4), the upper partition (3), the upper reservoir (2), and the top of the pressure-resistant sealed container (1) in sequence and is connected to the distributed optical fiber strain sensor demodulator (16).

2. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 1, characterized in that: The lower end of the sieve tube (71) is provided with a lower cover plate (75), and the lower cover plate (75) is provided with sieve holes.

3. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 1 or 2, characterized in that: The cover plate (74) is provided with sieve holes.

4. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 1, characterized in that: The pressure-resistant sealed container (1) includes an upper cover (101), a vertical frame (102), and a lower cover (103). The vertical frame (102) is located between the upper cover (101) and the lower cover (103). The lower end face of the upper cover (101) and the upper end face of the lower cover (103) are respectively provided with limiting sealing grooves (100) that match the vertical frame (102). The upper cover (101) and the lower cover (103) are fixedly connected by screws.

5. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 4, characterized in that: The vertical frame (102) includes a left side cover (1021), a right side cover (1022), a front side panel (1023), and a rear side panel (1024). The left cover (1021) and the right cover (1022) are arranged opposite to each other. The left cover (1021) is provided with two injection holes (10211), and the right cover (1022) is provided with two outflow holes (10221). The front side panel (1023) and the rear side panel (1024) are arranged opposite to each other.

6. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 5, characterized in that: It also includes the lower reservoir injection channel (17), the upper reservoir injection channel (18), the upper reservoir outflow channel (19) and the lower reservoir outflow channel (20). The lower reservoir injection channel (17) and the upper reservoir injection channel (18) are respectively located in the injection hole (10211); The upper reservoir outflow channel (19) and the lower reservoir outflow channel (20) are respectively located in the outflow hole (10221).

7. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 1, characterized in that: The upper reservoir (2), the interlayer (4), and the lower reservoir (6) are artificial rock cores formed on-site by cementing resin and sand particles in a preset ratio.

8. The experimental system for water injection profile evolution based on distributed optical fiber strain sensing according to claim 1, characterized in that: The upper reservoir injection pump (10) and the lower reservoir injection pump (11) are variable frequency plunger pumps.

9. An experimental method for water injection profile evolution based on distributed optical fiber strain sensing, characterized in that, The experimental system for water injection profile evolution based on distributed optical fiber strain sensing as described in any one of claims 1 to 8 includes the following steps: S1. Prepare a reservoir simulation system and connect the injection-production simulation system and the strain measurement system to the reservoir simulation system; S2. Open the back pressure valve (13) and use the upper reservoir injection pump (10) and lower reservoir injection pump (11) to send water of different flow rates into the upper reservoir (2) and lower reservoir (6) respectively. The produced water is returned to the water storage tank (8) through the production well (9), the outflow pipeline (12), the back pressure valve (13), and the return liquid pipeline (14), thus realizing the simulation of the layered water injection and combined layer mining process. S3. Close the back pressure valve (13) to keep the production wellbore (9) from flowing out. When the pressure of the lower reservoir (6) is greater than the downward spring force of the lower spring (72), the sealing plate (73) opens and water is injected into the interlayer (4) to simulate the interlayer flow in the far well zone. During the S4, S2 and S3 tests, the distributed fiber optic strain demodulator (16) collects the strain values ​​of each point along the vertical direction of the upper reservoir (2), the interlayer (4) and the lower reservoir (6) in real time through the steel armored optical cable (15). After the experiment is completed, the strain data collected by the distributed fiber optic strain sensor demodulator (16) is exported, and the strain distribution along the vertical direction of the upper reservoir (2), the interlayer (4) and the lower reservoir (6) is plotted.

10. The experimental method for water injection profile evolution based on distributed optical fiber strain sensing according to claim 9, characterized in that: In step S1, after the steel-armored optical cable (15) and the distributed optical fiber strain sensor demodulator (16) are connected, the distributed optical fiber strain sensor demodulator (16) is started, and the measurement point is located by tapping the steel-armored optical cable (15) at the top outlet of the pressure-resistant sealed container (1).

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