Visual multi-scale fracture physical experiment model

Abstract

The invention belongs to the technical field of oil reservoir development and research, and particularly relates to a visual multi-scale fracture physical experiment model. The device specifically comprises an injection hole channel and an extraction hole channel which penetrate through a bottom plate, and a plurality of control valves are arranged above the injection hole channel and the extraction hole channel and used for controlling the injection-extraction relation. The method further comprises a fracture depicting area to simulate fracture distribution of the fractured reservoir. The device further comprises a plurality of hollow communication hole channels located in the bottom plate and used for simulating communication between different perforation fracturing sections of the injection well and the production well and cracks in the crack depicting area. Control valves are arranged on the communication hole channels and used for controlling the number of the perforation fracturing sections; reservoir characteristics of fractures of different sizes of the fractured reservoir can be reflected, different injection-production relations can be simulated by controlling the valve, and the seepage velocity, the seepage volume and the seepage direction of fluid along different fractures under different injection-production relations can be visually observed, so that a basis is provided for development of the fractured reservoir.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir development research, and in particular relates to a visualized multi-scale fracture physical experimental model. Background Art

[0002] There are usually many fractures of different scales and directions in fractured reservoirs. In order to improve the development effect, fractured reservoirs often need to be supplemented with energy after a period of natural energy development, mostly by gas injection or water injection. However, due to the existence of fractures, most of the injected gas or water flows from the fractures into the production well, which cannot achieve the purpose of effective energy supplement. In order to improve the development effect of gas or water injection in fractured reservoirs, it is usually necessary to first block the crossflow channel to expand the scope of gas drive or water drive. For fracture plugging, injection parameters such as the size of the plugging agent segment, the combination of the segment, and the injection speed of the segment will greatly affect the distribution of the plugging agent in fractures of different scales, and then affect the final plugging effect of the plugging agent. However, there is currently no effective means or method to intuitively reflect the influence of the injection parameters of the plugging agent on the migration or distribution of the plugging agent in fractures of different scales. Therefore, inventing a visual multi-scale fracture physical model and formulating a suitable experimental method is of great significance to improve the plugging effect of the plugging agent in fractured reservoirs and ultimately improve the development effect of fractured reservoirs.

[0003] In terms of the production of a visualized multi-scale fracture physical model, a Chinese invention patent application with application publication number CN114910391A discloses an experimental device and method for evaluating the multi-stage profile control performance of microbial cement in fractured oil reservoirs, which includes a visualized multi-stage fracture model, which is made of two rectangular glass plates encapsulated by epoxy resin, forming a cavity inside, and a multi-stage fracture cavity structure using rock plates to simulate fractures is vertically arranged in the cavity, and a liquid inlet is opened on one side of the diagonal direction of the cavity, and a liquid outlet is opened on the other side. The model can visually observe the distribution of oil and water in multi-stage fractures during saturated oil and primary water flooding; it can visually observe the distribution of microorganisms in fractures, the formation process of microbial metabolites, and the flow direction of water in secondary water flooding after microbial metabolites are blocked, etc., but it cannot simulate the distribution of injected fluids in fractures of different scales under different injection and production methods and when different perforation and fracturing sections of horizontal wells communicate with fractures, and it cannot quantitatively reflect the amount of injected fluids entering fractures of different scales. Summary of the invention

[0004] The purpose of the present invention is to provide a visualized multi-scale fracture physical experimental model to solve the problem that the prior art cannot simulate the migration of injected fluids in fractures of different scales and the amount of migration.

[0005] In order to solve the above technical problems, the present invention provides a visualized multi-scale fracture physical experimental model, comprising a cover plate and a bottom plate, wherein the cover plate is located above the bottom plate and a reservoir simulation area is formed between the cover plate and the bottom plate, and the model is characterized in that it also comprises two hollow channels penetrating the bottom plate, respectively called injection channels and production channels, which are used to simulate injection wells and production wells, respectively, and connecting valves are respectively provided at the channel openings of the injection channel and the production channel to control whether they are connected with the displacement device; a plurality of valve channels are provided above the injection channel and the production channel to enable The injection channel and the production channel form several sections to simulate the perforation and fracturing section, and the valve channel is equipped with a control valve for controlling the injection-production relationship; it also includes a fracture characterization area located in the reservoir simulation area to simulate the fracture distribution of the fracture reservoir; it also includes several hollow communication channels located on the bottom plate, the communication channels connect the perforation and fracturing section with the fracture characterization area, and the communication channels are used to simulate the communication between different perforation and fracturing sections of the injection well and the production well and the fractures in the fracture characterization area; each communication channel is provided with a valve channel, and the valve channel is equipped with a control valve.

[0006] The beneficial effects are as follows: in order to solve the problem that the prior art cannot simulate the migration conditions and migration amounts of injected fluids in fractures of different scales, a physical experimental model designed by the present invention can reflect the reservoir characteristics of fractures of different scales in fractured oil reservoirs, and can simulate different injection-production relationships by controlling valves. The seepage velocity, seepage volume, and seepage direction of the fluid along different fractures under different injection-production relationships can be intuitively observed to quantitatively describe the migration amounts of injected fluids in fractures of different scales, thereby providing a basis for the development of fractured oil reservoirs.

[0007] Furthermore, the fracture characterization area includes at least one of the following fracture types: vertical fractures, parallel fractures and oblique fractures, and the scale of each type of fracture is different.

[0008] The beneficial effects are: providing fractures of different sizes and staggered conditions, making the simulation experiment more realistic, and reflecting the reservoir characteristics of fractures of different scales in fractured reservoirs.

[0009] Furthermore, a sealing device is included to achieve sealing between the model cover plate and the crack characterization area.

[0010] The beneficial effect is to prevent gas leakage in fracture reservoirs of different scales in the simulated fractured oil reservoir and ensure the accuracy of the experiment.

[0011] Furthermore, three control valves are provided on the injection channel and the production channel.

[0012] Furthermore, the cover plate and the bottom plate are fixed with screws.

[0013] Its beneficial effects are: ensuring the stability of the experimental model to observe the seepage velocity, seepage volume and seepage direction of the fluid along different fractures under different injection-production relationships, and providing a basis for the development of fractured oil reservoirs.

[0014] Furthermore, the injection-production relationship includes any one of the injection-production methods: one injection-one production, one injection-two productions, two injections-one production, and two injections-two productions.

[0015] The beneficial effects are: multiple injection-production relationships can be selected, making the scenarios simulated by the manufactured experimental model more diverse, and providing a basis for various on-site plugging agent dosages and slug designs.

[0016] Furthermore, the cover plate and the bottom plate are both made of glass fiber board.

[0017] Furthermore, the experimental model is a rectangular parallelepiped model. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an illustration of screws, valves, and inlets and outlets in the overall top view of the visualized multi-scale fracture physical model device of the present invention;

[0019] Figure 2 It is a crack illustration diagram in the overall top view of the visualized multi-scale crack physical model of the present invention;

[0020] Figure 3 is a top view of the top plate of the visualized multi-scale fracture physical model of the present invention;

[0021] Figure 4 It is a schematic diagram of the long side of the visualized multi-scale fracture physical model of the present invention;

[0022] Figure 5 It is a schematic diagram of the short side of the visualized multi-scale fracture physics model of the present invention.

[0023] Among them, 1- No. 1 inlet; 2- No. 1 screw; 3- No. 2 screw; 4- No. 3 screw; 5- No. 4 screw; 6- No. 5 screw; 7- No. 1 outlet; 8- No. 1 outlet valve; 9- No. 6 screw; 10- No. 2 outlet valve; 11- No. 2 outlet; 12- No. 3 outlet valve; 13- No. 7 screw; 14- No. 4 outlet valve; 15- No. 8 screw; 16- No. 5 outlet valve; 17- No. 3 outlet; 18- No. 9 screw; 19- No. 10 screw; 20- No. 11 screw; 21- No. 12 screw; 22- No. 13 screw; 23- No. 14 screw; 24- Screw No. 15; 25-Screw No. 16; 26-Screw No. 17; 27-Inlet No. 3; 28-Inlet valve No. 1; 29-Screw No. 18; 30-Inlet valve No. 2; 31-Inlet No. 2; 32-Inlet valve No. 3; 33-Screw No. 19; 34-Inlet valve No. 4; 35-Screw No. 20; 36-Inlet valve No. 5; 37-Visualized multi-scale crack physical model; 38-First etching crack; 39-Second etching crack; 40-First center hole crack; 41-Third etching crack; 42-Fourth etching crack; 43-No. 1 etching sealing groove; 4 4-fifth etching crack; 45-sixth etching crack; 46-seventh etching crack; 47-eighth etching crack; 48-ninth etching crack; 49-tenth etching crack; 50-eleventh etching crack; 51-twelfth etching crack; 52-thirteenth etching crack; 53-fourteenth etching crack; 54-fifteenth etching crack; 55-second center hole crack; 56-third center hole crack; 57-sixteenth etching crack; 58-seventeenth etching crack; 59-fourth center hole crack, 60-eighteenth etching crack; 61-second etching sealing groove; 62-nineteenth etching Etching cracks; 63-the twentieth etching crack; 64-the twenty-first etching crack; 65-the twenty-second etching crack; 66-the twenty-third etching crack; 67-the twenty-fourth etching crack; 68-the twenty-fifth etching crack; 69-the twenty-sixth etching crack; 70-the twenty-seventh etching crack; 71-the twenty-eighth etching crack; 72-the twenty-ninth etching crack; 73-the thirtieth etching crack; 74-the fifth center hole crack; 75-the sixth center hole crack; 76-the thirty-first etching crack; 77-the thirty-second etching crack; 78-injection horizontal section; 79-production horizontal section. DETAILED DESCRIPTION

[0024] The basic concept of the present invention is to make a visualization model body with two layers of simulated fractures, with simulation wells running through the entire model between the bodies, and fractures of different scales and communication fractures between fractures between the simulation wells. The fractures of the simulation wells are designed according to actual conditions, and different media are injected into the simulation wells and the length of the media entering the fractures of different scales is recorded to simulate the speed and quantity of different injection media entering the fractures of different scales at different injection amounts, injection speeds and injection concentrations, which has important guiding significance for the injection parameters of the injection media in the actual development of multi-scale fracture reservoirs. Based on this concept, a visualization multi-scale fracture physical model device and its experimental method of the present invention can be realized.

[0025] The present invention will be described in detail below with reference to the accompanying drawings and method embodiments.

[0026] Example of a visual multi-scale fracture physics experimental model:

[0027] A visualized multi-scale fracture physics experimental model of the present invention, such as Figure 1 to Figure 5 As shown, the model specifically includes:

[0028] 1) The main body of the model device is a rectangular parallelepiped model, which is formed by locking two glass fiber boards of a certain thickness with screws. The two glass fiber boards are respectively a cover plate and a bottom plate. Holes are punched on the cover plate and screws and valves are installed. Hollow channels (i.e., injection channels and production channels) that run through the long sides of the bottom plate are drilled on both sides close to the short sides of the bottom plate to simulate injection wells and production wells. Suitable nozzle valves are installed at both ends of the channels to connect with the displacement device. Three valve channels are drilled at both ends and in the middle of the channels and control valves are installed to control the injection-production relationship. Hollow channels are drilled in the middle of the short sides of the bottom plate to connect with the simulated injection well or the simulated production well, and the injection-production relationship is controlled together with the valves on the simulated injection well and the production well. A nozzle valve is installed at the intersection of the short sides of the channels to connect with the displacement device.

[0029] 2) An area (reservoir simulation area) for simulating reservoir fractures is formed between the cover plate and the bottom plate and at a certain distance from the short side of the bottom plate. A number of fractures of different widths, depths and lengths are engraved in the reservoir simulation area according to the fracture distribution of the fracture reservoir, wherein the width and depth of each fracture are kept consistent, so as to simulate the fracture distribution of the fracture reservoir; fracture grooves are engraved at a certain position outside the fracture engraving area, for placing sealing strips to seal the whole model; a hollow channel (communication channel) is drilled in the bottom plate at the middle position of the fracture engraving area near the short side of the model to communicate with the simulated injection well or the simulated production well, and a hole is drilled on the top and a control valve is installed to control the injection-production relationship and the number of crossflow sections of the horizontal well; holes are drilled in the bottom plate and screws are installed, and the positions of the screws and valves must match those of the screws and valves of the cover plate to ensure that the cover plate fits well with the bottom plate and the device is reliably sealed; the model is sealed by screws and sealing rings.

[0030] The glass bottom plate and glass cover plate of the model device are 60cm×40cm×4cm in size, and are cut by mechanical cutting. The screw holes and valve holes are processed on the glass cover plate by ultrasonic drilling, and suitable screws and valves are installed. A notching knife is used to notch the cracks in the area 10cm away from the short side and 8cm away from the long side of the bottom plate. The sizes of the cracks include four sizes: width×depth of 0.5mm×0.5mm, 1mm×1mm, 2mm×2mm and 4mm×3mm. Figure 2As shown, the width × depth of the etching cracks numbered 45, 47, 41, 38, 49, 51 and 53 is 2mm × 2mm; the width × depth of the etching cracks numbered 64, 68, 72, 73, 69, 65, 63, 60 and 57 is 0.5mm × 0.5mm; the width × depth of the etching cracks numbered 44, 46, 76, 71, 67, 77, 62, 58, 70 and 66 is 1mm × 1mm; the width × depth of the etching cracks numbered other than 4mm × 3mm; the size of each crack grid is 4cm × 2.5cm; a rectangular seam is etched in an area 9cm from the short side and 7cm from the long side of the bottom plate, namely, the No. 1 etching sealing groove, the size of the rectangle is 42cm × 12cm, and the size of the seam is 1mm × 1mm in width. In the experiment, a sealing material is placed in the rectangular seam. The device is sealed with an appropriate sealing ring; a hole is drilled at a distance of 6 cm from the short side of the bottom plate and in the middle of the thickness of the bottom plate by the ultrasonic drilling method (the injection horizontal section and the production horizontal section numbered 78 and 79). The drilled hole is a circular hole with a diameter of 2 mm and connects the two long sides of the bottom plate to simulate the horizontal sections of the injection well and the production well; a hole is drilled at a distance of 5 cm from the short side of the bottom plate and 13 cm from the long side of the bottom plate by the ultrasonic drilling method (the central hole seam numbered 40, 55, 59 and 74). The length of the hole is 5 cm, and the two ends are respectively connected with the horizontal section and the edge of the fracture area; a hole is drilled in the middle of the short side by the ultrasonic drilling method (the central hole seam numbered 56 and 75). The drilled hole must communicate with the horizontal sections of the injection well and the production well to simulate different injection and production positions and the corresponding relationship between injection and production of the injection well and the production well.

[0031] The specific experimental steps of the above physical experimental model include:

[0032] Step 1: Assemble the bottom plate and cover plate of the visual multi-scale crack model together.

[0033] Step 2: prepare dyed experimental fluid, such as dyed water, polymer, plugging agent system, etc., and load it into the intermediate container in the displacement device.

[0034] Step three, connect the displacement device to one or two of the inlet ends (inlets numbered 1, 27 and 31) of the visualized multi-scale fracture model, and control the switch of the inlet valves numbered 36, 32 and 28 to simulate the number of injection wells or sections and different connectivity conditions of the fractures. At the same time, use the switch of the outlet valves numbered 8, 12 and 16 to control the opening degree of the outlet end (outlets numbered 7, 11 and 17) to simulate the number of production wells or sections and different connectivity conditions of the fractures.

[0035] Step 4: Inject water into the model, observe and record the time and length of the injected water entering fractures of different scales. This can analyze the order and volume of the injected water entering fractures of different scales under different injection-production correspondences and different fracture connectivity states, and further clarify the seepage law of the injected water under different injection-production correspondences and different fracture connectivity states.

[0036] Step five, inject polymers with different viscosities into the model, observe and record the time and length of polymers with different viscosities entering fractures of different scales, so as to analyze the order and volume of polymers with different viscosities entering fractures of different scales under different injection-production correspondences and different fracture connectivity states, and then clarify the seepage laws of polymers with different viscosities under different injection-production correspondences and different fracture connectivity states, providing a basis for the design of on-site plugging agent segments.

[0037] Inject the plugging agent system into the model and make it gel, then inject water, observe and record the time and length of the injected water entering the fractures of different sizes, and then clarify the scope of the injected water after the plugging agent is blocked;

[0038] Different volumes of plugging agent systems with different viscosities are injected into the model, and the time and length of different volumes of plugging agent systems with different viscosities entering fractures of different scales are observed and recorded. Water is injected after the plugging agent is gelled, and the time and length of the injected water entering fractures of different scales are observed and recorded. This can clarify the seepage laws of different volumes of plugging agent systems with different viscosities under different fracture connectivity states and expand the affected volume range.

[0039] The injected water in this embodiment can also be replaced by gas to evaluate the conditions of different injection media at different injection rates.

[0040] The model device of the present invention can visualize the injection process of fluids in different scale fractures of the oil reservoir at different stages, and can directly observe the migration of fluids in fractures of different scales; it can quantitatively describe the migration amount of injected fluids in fractures of different scales; it can also simulate different injection and production well network modes and multi-stage crossflow of horizontal wells in oil field development; according to the simulation of the speed and amount of different injection media entering fractures of different scales at different injection amounts, injection speeds and injection concentrations, it has important guiding significance for the injection parameters of the injection media in the actual development of multi-scale fractured oil reservoirs.

Claims

1. A visualized multi-scale fracture physical experimental model, comprising a cover plate and a bottom plate, wherein the cover plate is located above the bottom plate and a reservoir simulation area is formed between the cover plate and the bottom plate, characterized in that: It also includes two hollow channels that penetrate the bottom plate, respectively called injection channels and production channels, which are used to simulate injection wells and production wells, and connecting valves are respectively provided at the channel openings of the injection channels and the production channels to control whether they are connected with the displacement device; a number of valve channels are provided above the injection channels and the production channels, so that the injection channels and the production channels form a number of sections to simulate the perforation and fracturing sections, and the valve channels are equipped with control valves to control the injection-production relationship; it also includes a fracture characterization area located in the reservoir simulation area to simulate the fracture distribution of the fracture reservoir; it also includes a number of hollow communication channels located on the bottom plate, the communication channels connect the perforation and fracturing sections with the fracture characterization areas, and the communication channels are used to simulate the communication between different perforation and fracturing sections of the injection well and the production well and the fractures in the fracture characterization area; each communication channel is provided with a valve channel, and the valve channel is equipped with a control valve.

2. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: The fracture characterization area includes at least one of the following fracture types: vertical fractures, parallel fractures and oblique fractures, and the scale of each type of fracture is different.

3. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: A sealing device is also included for achieving sealing between the model cover plate and the crack depiction area.

4. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: There are three control valves on the injection channel and the production channel.

5. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: The cover plate and the base plate are fixed with screws.

6. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: The injection-production relationship includes: one injection and one production, one injection and two productions, two injections and one production, and two injections and two productions.

7. The visualized multi-scale fracture physics experimental model according to claim 1, characterized in that: The cover and base are both made of fiberglass.

8. The visualized multi-scale fracture physics experimental model according to any one of claims 1 to 7, characterized in that: The experimental model is a rectangular parallelepiped model.

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