Artificial rock core capable of directly observing measurement wave and coefficient expansion process and experimental method thereof

Abstract

The invention discloses an artificial rock core capable of directly observing a measurement wave and coefficient expansion process and an experimental method thereof, and belongs to the technical field of oil exploitation. The artificial rock core comprises an open container composed of a group of oppositely-arranged transparent plates, a plurality of layers of quartz sand are sequentially laid in the open container from bottom to top and symmetrically distributed with a middle layer as the center, and the granularity of the quartz sand is gradually increased from the bottom layer to the middle layer and then gradually decreased from the middle layer to the top layer; a group of oppositely arranged transparent plates of the open container are respectively used as an injection plate and an oil outlet plate, a first through hole and a second through hole which are positioned at the same height are correspondingly formed in the injection plate and the oil outlet plate, and a third through hole and a fourth through hole are symmetrically formed above and below the second through hole; the height of the forming positions of the first through hole and the second through hole is within the range of the middle layer. The measurement wave and coefficient expansion process can be directly observed through the artificial rock core.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum exploitation, and in particular relates to an artificial rock core and an experimental method thereof which can directly observe and measure a sweep coefficient expansion process. Background Art

[0002] During the development of oil reservoirs, the sweep coefficient changes continuously. Its size and changing rules play an important role in evaluating the effect of oil field development and formulating measures. Cores are needed to observe its changing rules. Artificial cores can overcome the problem of high sampling costs and have excellent experimental repeatability.

[0003] As in the prior art, a Chinese invention patent with publication number CN118225650A discloses an artificial core preparation method, product, medium and equipment based on a two-dimensional digital core. The preparation method is as follows: drilling a natural core to obtain a target porosity and a target permeability; testing to obtain the particle size classification result of the natural core and generating a particle model with different particle size ratios; performing uniaxial compression on the particle model to measure the measured porosity; calculating the porosity error between the measured porosity and the target porosity and roughly adjusting the particle model until the porosity error is less than the porosity error threshold to obtain a digital core; performing a Darcy seepage simulation experiment on the digital core to calculate the measured permeability of the digital core; fine-tuning the particle model until the permeability error between the measured permeability and the target permeability is less than the permeability error threshold, and recording the final particle ratio of different particle sizes for preparing the artificial core. Another example is a method for preparing an artificial core with a complex structure disclosed in a Chinese invention patent with publication number CN115597930A, which is as follows: determine the mass fraction of the constituent minerals of the taken sandstone and mudstone; calculate a first content according to the mass fraction of the constituent minerals of the sandstone, the first content including the quartz content, clay mineral content and cement content in the sandstone; calculate a second content according to the mass fraction of the constituent minerals of the mudstone, the second content including the quartz content, feldspar content and clay mineral content in the mudstone; configure a sand cake according to the first content, and configure a mud cake according to the second content; weigh the configured sand cake or mud cake according to the mass of each layer of the sand-mud interlayer artificial core, and compact it to make a sand-mud interlayer artificial core; or weigh the configured sand cake according to the mass of each layer of the artificial sandstone core, and compact it to make an artificial sandstone core.

[0004] The above-mentioned prior art experiments utilize artificial cores that are close to the real situation to obtain accurate simulation results, but the above-mentioned artificial cores cannot intuitively obtain the sweep coefficient expansion process and sweep coefficient expansion value. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an artificial core and an experimental method thereof for directly observing and measuring the process of enlargement of the wave coefficient, through which the process of enlargement of the wave coefficient can be directly observed and measured.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: On one hand, the present invention provides an artificial core capable of directly observing and measuring the process of sweep coefficient expansion, comprising an open container composed of a group of relatively arranged transparent plates, wherein a plurality of layers of quartz sand are sequentially laid from bottom to top in the interior of the open container, wherein the plurality of layers of quartz sand are symmetrically distributed with the middle layer as the center, and the particle size of the quartz sand gradually increases from the bottom layer to the middle layer, and then gradually decreases from the middle layer to the top layer; A group of transparent plates arranged opposite to each other in the open container are used as an injection plate and an oil outlet plate respectively, and a first through hole and a second through hole located at the same height are correspondingly opened on the injection plate and the oil outlet plate, and a third through hole and a fourth through hole are symmetrically opened above and below the second through hole; The opening heights of the first through hole and the second through hole are within the range of the middle layer.

[0007] In one embodiment, a layer of river sand is laid between the two adjacent layers of quartz sand.

[0008] In one embodiment, the particle size of the river sand is 40-60 mesh.

[0009] In one embodiment, the quartz sand and river sand are respectively immersed in liquid paraffin for pretreatment; the volume ratio of the quartz sand to the liquid paraffin is 1:(1-3); the volume ratio of the river sand to the liquid paraffin is 1:(1-3).

[0010] In one embodiment, the filling height of a layer of the river sand is 0.1 cm.

[0011] In one embodiment, the filling height of each layer of quartz sand is 1.0-1.1 cm.

[0012] In one embodiment, several layers of quartz sand are laid from bottom to top in order, and the particle sizes are 80-120 mesh, 60-80 mesh, 40-60 mesh, 20-40 mesh, 40-60 mesh, 60-80 mesh, and 80-120 mesh.

[0013] In one embodiment, the top of the open container is sealed using hot melt adhesive.

[0014] The present invention also provides an experimental method based on an artificial core capable of directly observing and measuring the process of sweep coefficient expansion, comprising the following steps: Inject pigmented water into the artificial core until a stable water flow channel is obtained and measure the water displacement area; Inject a polyacrylamide solution with pigment into the artificial core until a stable polyacrylamide solution channel is obtained, and measure the displacement area of ​​the polyacrylamide solution; continuously record the shape of the polyacrylamide solution displacement and observe the expansion process of the sweep coefficient; Calculate the sweep coefficients of water and polyacrylamide solutions.

[0015] In one embodiment, the specific process is as follows: insert a needle tube into the first through hole of the injection plate of the open container as the injection end; insert a needle tube into the second through hole, the third through hole and the fourth through hole of the oil outlet plate as the oil outlet end; Water with pigment is injected from the injection end until a stable water flow channel is obtained, and the water displacement area is measured; Inject the polyacrylamide solution with pigment from the injection end until a stable polyacrylamide solution channel is obtained, and measure the displacement area of ​​the polyacrylamide solution; continuously record the shape of the polyacrylamide solution displacement and observe the expansion process of the sweep coefficient; Calculate the sweep coefficients of water and polyacrylamide solutions.

[0016] In one embodiment, the formula for calculating the sweep coefficient of water and polyacrylamide solution is as follows: E a =S a / S Among them, S a is the water displacement area or the polyacrylamide solution displacement area, E a is the sweep coefficient of water or the sweep coefficient of polyacrylamide solution; S is the cross-sectional area of ​​the open container.

[0017] Furthermore, the injection flow rates of the water containing the pigment and the polyacrylamide solution containing the pigment are the same.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an artificial core that can directly observe and measure the process of sweep coefficient expansion. The artificial core is visible, and the particle size of the quartz sand filled inside gradually increases from the bottom layer to the middle layer, and then gradually decreases from the middle layer to the top layer; this arrangement allows the core to form an obvious permeability gradient in the vertical direction. The existence of the permeability gradient simulates the heterogeneity of permeability in natural formations, making the experiment closer to actual formation conditions. Due to the existence of the permeability gradient, the seepage behavior of liquids of different viscosities in the core will be different, and high permeability areas will be more easily immersed in liquids. By directly observing the seepage process of the liquid in the core, the change in sweep coefficient can be clearly seen, thereby gaining a deeper understanding of the seepage law of the liquid in the formation.

[0019] The present invention also provides an experimental method based on an artificial core that can directly observe and measure the process of sweep coefficient expansion. The visible artificial core used in this method uses sand particles of different particle sizes to form a significantly different permeability environment under natural accumulation, and obtains a permeability gradient formed along the direction of particle size change. It can directly observe that after the liquid enters the high permeability area, liquids of different viscosities can be immersed in different areas, thereby expressing the influencing factors of the sweep coefficient change. The artificial core can directly observe the sweep coefficient expansion process and expansion value. At the same time, a brightly colored path is used to track the fluid for better observation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the results of water injection performed in Example 1 of the present invention; Figure 2 This is a schematic diagram of the result of injecting a polyacrylamide solution in Example 1 of the present invention; Figure 3 A schematic diagram of an open container according to an embodiment of the present invention; Figure 4 A top view of an open container according to an embodiment of the present invention; Figure 5 Figures (a) and (b) are side and cross-sectional views of an open container according to an embodiment of the present invention; Figure 6 This is a cross-sectional view of an open container according to Example 2 of the present invention.

[0021] Among them: 1-open container; 2-injection plate; 3-oil outlet plate; 4-first through hole; 5-second through hole; 6-third through hole; 7-fourth through hole. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 3 , Figure 4 and Figure 5 The present invention provides an artificial core for directly observing and measuring the process of expansion of the sweep coefficient, the artificial core comprising an open container 1 composed of a group of relatively arranged transparent plates, an injection plate 2, an oil outlet plate 3, a first through hole 4, a second through hole 5, a third through hole 6, a fourth through hole 7 and several layers of quartz sand filled and laid inside the open container 1.

[0025] Among them, several layers of quartz sand are laid in sequence from bottom to top inside the open container, and the several layers of quartz sand are symmetrically distributed with the middle layer as the center. The particle size of the quartz sand gradually increases from the bottom layer to the middle layer, and then gradually decreases from the middle layer to the top layer.

[0026] Furthermore, a layer of river sand is laid between two adjacent layers of quartz sand, and the particle size of the river sand is 40~60 mesh.

[0027] The quartz sand and river sand are respectively immersed in liquid paraffin for pretreatment; the volume ratio of quartz sand to liquid paraffin is 1: (1-3); the volume ratio of river sand to liquid paraffin is 1: (1-3).

[0028] The filling height of each layer of quartz sand is 1.0-1.1 cm, and the filling height of each layer of river sand is 0.1 cm.

[0029] In a specific embodiment, several layers of quartz sand are laid from bottom to top in order, and the particle sizes are 80-120 mesh, 60-80 mesh, 40-60 mesh, 20-40 mesh, 40-60 mesh, 60-80 mesh, and 80-120 mesh.

[0030] A set of relatively transparent plates of the open container 1 are used as the injection plate 2 and the oil outlet plate 3. A first through hole 4 and a second through hole 5 are correspondingly opened on the injection plate 2 and the oil outlet plate 3. The opening heights of the two holes are within the range of the middle layer and are located at the same height. In addition, a third through hole 6 and a fourth through hole 7 are symmetrically opened above and below the second through hole 5.

[0031] Furthermore, the top of the open container 1 is sealed with hot melt adhesive.

[0032] In a specific embodiment, the method for preparing the artificial core capable of directly observing and measuring the process of sweep coefficient expansion is as follows: Step 1: select quartz sand with particle sizes of 20-40 mesh, 40-60 mesh, 60-80 mesh, 80-120 mesh, and river sand with particle sizes of 40-60 mesh, and soak them in liquid paraffin for 3-5 hours at a volume ratio of 1: (1-3); Step 2: Use 10*10*0.2cm 3 The acrylic plate is made into a rectangular open container 1 with an inner length of 7-8 cm, a width of 0.3 mm, and a height of 8-9 cm. A hole with a diameter of 0.3 mm is drilled at a distance of 3.8-4.1 cm from the bottom edge on the oil outlet plate 3 at one end, namely the first through hole 4. Holes with a diameter of 0.3 mm are drilled at a distance of 1.6-1.7 cm, 3.8-4.1 cm, and 6.0-6.5 cm from the bottom edge on the injection plate 2 at the other end, namely the third through hole 6, the second through hole 5, and the fourth through hole 7, respectively. The open container 1 is dried for 40 minutes. Step 3, filling the quartz sand in step 1 with the particle sizes of 80-120 mesh, 60-80 mesh, 40-60 mesh, 20-40 mesh, 40-60 mesh, 60-80 mesh, and 80-120 mesh from bottom to top into the open container 1 obtained in step 2, and marking the boundary of each layer of quartz sand with the river sand in step 1; Step 4: Seal the opening with hot melt adhesive.

[0033] In another aspect, the present invention also provides an experimental method based on an artificial core capable of directly observing and measuring the process of sweep coefficient expansion, comprising the following steps: A needle is inserted into the first through hole 4 on the injection plate 2 of the open container 1 as an injection end; needles are inserted into the second through hole 5, the third through hole 6 and the fourth through hole 7 on the oil outlet plate 3 as an oil outlet end; Inject pigmented water into the artificial core from the injection end until a stable water flow channel is obtained, and measure the water displacement area; Inject the polyacrylamide solution with pigment into the artificial core from the injection end until a stable polyacrylamide solution channel is obtained, and measure the displacement area of ​​the polyacrylamide solution; continuously record the shape of the polyacrylamide solution displacement and observe the expansion process of the sweep coefficient; Calculate the sweep coefficients of water and polyacrylamide solutions.

[0034] The above formula for calculating the sweep coefficient of water and polyacrylamide solution is as follows: E a =S a / S Among them, S a is the water displacement area or the polyacrylamide solution displacement area, E a is the sweep coefficient of water or the sweep coefficient of polyacrylamide solution; S is the cross-sectional area of ​​the open container.

[0035] In a specific implementation process, the experimental method is as follows: Step 1: Take 100ml of 0.1% polyacrylamide solution and add four drops of water-soluble pigment.

[0036] Step 2: Take 100 ml of water and add four drops of the water-soluble pigment in step 1.

[0037] Step three: insert a 0.3mm diameter needle into the high permeability area at one end 3.8~4.1cm away from the bottom edge as the injection end, and insert a 0.3mm diameter needle into the other end at 1.6~1.7cm, 3.8~4.1cm, and 6.0~6.5cm away from the bottom edge as the oil outlet.

[0038] Step 4: Inject water at a flow rate of 3 ml / min until a stable water flow channel is obtained, that is, the oil phase can no longer be discharged, and use ImageJ software to measure the water displacement area S a1 .

[0039] Step 5: Use a polyacrylamide solution with a viscosity of 27 mPas to inject at the same flow rate, record the shape of the polyacrylamide solution displacement every 1 minute, and observe the expansion process of the sweep coefficient.

[0040] Step 6: When a stable polyacrylamide solution channel is obtained, that is, the oil phase cannot be further extracted (about 15 minutes), the displacement area S of the polyacrylamide solution is measured using ImageJ software. a2 .

[0041] Step 7: Through E a =S a / S to obtain the sweep coefficient of water and the sweep coefficient of polyacrylamide solution.

[0042] The present invention is further described below in conjunction with specific embodiments.

[0043] Example 1 This embodiment provides a process for preparing an artificial core that can directly observe and measure the process of sweep coefficient expansion.

[0044] (1) Quartz sand with particle sizes of 20-40 mesh, 40-60 mesh, 60-80 mesh, 80-120 mesh, and river sand with particle size of 40-60 mesh were selected, and immersed in liquid paraffin for 3 h at a volume ratio of 1:1; (2) Use 10*10*0.2cm 3 The acrylic plate is made into an open container 1 of a rectangular shape with an inner length of 7 cm, a width of 0.3 mm, and a height of 8 cm. Holes with a diameter of 0.3 mm are drilled at 3.8 cm from the bottom edge at one end and 1.6 cm, 3.8 cm, and 6.0 cm from the bottom edge at the other end, and the open container is dried for 40 minutes; (3) Fill the particles in step 1 with quartz sand of particle sizes of 80-120 mesh, 60-80 mesh, 40-60 mesh, 20-40 mesh, 40-60 mesh, 60-80 mesh, and 80-120 mesh in order from bottom to top into the open container 1 obtained in step (2), wherein the quartz sand filling height is 1.0 cm, and mark the boundary of each layer of quartz sand with the river sand in step 1, wherein the river sand filling height is 0.1 cm; (4) Seal the opening with hot melt adhesive.

[0045] The artificial core prepared above, which can directly observe and measure the process of sweep coefficient expansion, is used for experiment. The specific steps are as follows: (1) Take 100 ml of 0.1% polyacrylamide solution and add four drops of water-soluble pigment.

[0046] (2) Take 100 ml of water and add four drops of the water-soluble pigment in step 1.

[0047] (3) Insert a 0.3 mm diameter needle into the high permeability zone at 3.8 cm from the bottom edge at one end as the injection end, and insert a 0.3 mm diameter needle into the other end at 1.6 cm, 3.8 cm, and 6.0 cm from the bottom edge as the oil outlet.

[0048] (4) Water was injected at a flow rate of 3 ml / min until a stable water flow channel was obtained, i.e., the oil phase could no longer be discharged (about 7 min). The water displacement area S was measured using ImageJ software. a1 .

[0049] (5) A polyacrylamide solution with a viscosity of 27 mPas was injected at the same flow rate. The shape of the polyacrylamide solution displacement was recorded every 1 min, and the expansion process of the sweep coefficient could be observed.

[0050] (6) After a stable polyacrylamide solution channel is obtained, that is, the oil phase can no longer be discharged (about 15 minutes), the displacement area S of the polyacrylamide solution is measured using ImageJ software. a2 .

[0051] (7) Through E a =S a / S to obtain the sweep coefficient of water and the sweep coefficient of polyacrylamide solution.

[0052] The range of water injection is Figure 1 As shown in Figure 2, the sweep coefficient of the polyacrylamide with a viscosity of 27 mPas increased from 0.13 to 0.39 after injection. Figure 2 shown.

[0053] Example 2 This embodiment provides a process for preparing an artificial core that can directly observe and measure the process of sweep coefficient expansion.

[0054] (1) Select quartz sand with particle sizes of 20-40 mesh, 40-60 mesh, 60-80 mesh, 80-120 mesh, and river sand with particle size of 40-60 mesh, and soak them in liquid paraffin for 5 hours at a volume ratio of 1:3; (2) If Figure 6 As shown, use 10*10*0.2cm 3 The acrylic plate is made into an open container 1 of a rectangular shape with an inner length of 8 cm, a width of 0.3 mm, and a height of 9 cm. Holes with a diameter of 0.3 mm are drilled at one end 4.1 cm away from the bottom edge and at the other end 1.7 cm, 4.1 cm, and 6.5 cm away from the bottom edge, and the open container 1 is dried for 40 minutes; (3) The particles in step 1 are filled with quartz sand of particle sizes of 80-120 mesh, 60-80 mesh, 40-60 mesh, 20-40 mesh, 40-60 mesh, 60-80 mesh, and 80-120 mesh in order from bottom to top into the open container 1 obtained in step (2), wherein the filling height of each layer of quartz sand is 1.1 cm, and the boundary of each layer of quartz sand is marked with the river sand in step 1, wherein the filling height of each layer of river sand is 0.1 cm; (4) Seal the opening with hot melt adhesive.

[0055] The artificial core prepared above, which can directly observe and measure the process of sweep coefficient expansion, is used for experiment. The specific steps are as follows: (1) Take 100 ml of 0.1% polyacrylamide solution and add four drops of water-soluble pigment.

[0056] (2) Take 100 ml of water and add four drops of the water-soluble pigment in step 1.

[0057] (3) Insert a 0.3 mm diameter needle into the high permeability zone at one end, 4.1 cm away from the bottom edge, as the injection end. Insert 0.3 mm diameter needles at the other end, 1.7 cm, 4.1 cm, and 6.5 cm away from the bottom edge, as the oil outlet ends.

[0058] (4) Water was injected at a flow rate of 3 ml / min until a stable water flow channel was obtained, i.e., the oil phase could no longer be discharged (about 7 min). The water displacement area S was measured using ImageJ software. a1 .

[0059] (5) A polyacrylamide solution with a viscosity of 27 mPas was injected at the same flow rate. The shape of the polyacrylamide solution displacement was recorded every 1 min, and the expansion process of the sweep coefficient could be observed.

[0060] (6) After a stable polyacrylamide solution channel is obtained, that is, the oil phase can no longer be discharged (about 15 minutes), the displacement area S of the polyacrylamide solution is measured using ImageJ software. a2 .

[0061] (7) Through E a =S a / S to obtain the sweep coefficient of water and the sweep coefficient of polyacrylamide solution.

[0062] In summary, the transparent artificial core prepared by the present invention uses sand particles of different particle sizes to form a significantly different permeability environment under natural accumulation, and obtains a permeability gradient formed along the particle size change direction. It can directly observe that after the liquid enters the high permeability area, liquids of different viscosities can be immersed in different areas, thereby expressing the influencing factors of the change in the sweep coefficient. The sweep coefficient expansion process and expansion value can be directly observed. At the same time, a brightly colored path is used to track the fluid for better observation.

[0063] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An artificial core capable of directly observing and measuring the process of enlargement of the sweep coefficient, characterized in that: It comprises an open container (1) composed of a group of transparent plates arranged opposite to each other, wherein a plurality of layers of quartz sand are laid in sequence from bottom to top inside the open container, the plurality of layers of quartz sand are symmetrically distributed with the middle layer as the center, and the particle size of the quartz sand gradually increases from the bottom layer to the middle layer, and then gradually decreases from the middle layer to the top layer; A group of transparent plates arranged opposite to each other in the open container (1) serve as an injection plate (2) and an oil outlet plate (3), respectively; a first through hole (4) and a second through hole (5) located at the same height are correspondingly opened on the injection plate (2) and the oil outlet plate (3); a third through hole (6) and a fourth through hole (7) are symmetrically opened above and below the second through hole (5); The opening heights of the first through hole (4) and the second through hole (5) are within the range of the middle layer.

2. The artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 1, characterized in that: A layer of river sand is laid between the two adjacent layers of quartz sand.

3. The artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 2, characterized in that: The particle size of the river sand is 40-60 mesh.

4. The artificial core capable of directly observing and measuring the process of enlargement of the wave coefficient according to claim 2, characterized in that: The quartz sand and river sand are respectively immersed in liquid paraffin for pretreatment; The volume ratio of the quartz sand to the liquid paraffin is 1:(1-3); The volume ratio of the river sand to the liquid paraffin is 1:(1-3).

5. The artificial core capable of directly observing and measuring the process of enlargement of the wave coefficient according to claim 2, characterized in that: The filling height of one layer of the river sand is 0.1 cm.

6. An artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 1 or 2, characterized in that: The filling height of each layer of quartz sand is 1.0-1.1 cm.

7. An artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 1 or 2, characterized in that: Several layers of quartz sand are laid from bottom to top, and the particle sizes are 80~120 mesh, 60~80 mesh, 40~60 mesh, 20~40 mesh, 40~60 mesh, 60~80 mesh, and 80~120 mesh.

8. The artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 1, characterized in that: The top of the open container (1) is sealed using hot melt adhesive.

9. An experimental method for an artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion based on any one of claims 1 to 8, characterized in that: The following steps are involved: A needle tube is inserted into the first through hole (4) on the injection plate (2) of the open container (1) as an injection end; and needle tubes are inserted into the second through hole (5), the third through hole (6) and the fourth through hole (7) on the oil outlet plate (3) as an oil outlet end; Inject pigmented water into the artificial core from the injection end until a stable water flow channel is obtained, and measure the water displacement area; Inject the polyacrylamide solution with pigment into the artificial core from the injection end until a stable polyacrylamide solution channel is obtained, and measure the displacement area of ​​the polyacrylamide solution; Continuously record the shape of the polyacrylamide solution displacement and observe the expansion process of the sweep coefficient; Calculate the sweep coefficients of water and polyacrylamide solutions.

10. The experimental method for an artificial core capable of directly observing and measuring the process of wave sweep coefficient expansion according to claim 9, characterized in that: The formula for calculating the sweep coefficient of water and polyacrylamide solution is as follows: E a =S a / S Among them, S a is the water displacement area or the polyacrylamide solution displacement area, E a is the sweep coefficient of water or the sweep coefficient of polyacrylamide solution; S is the cross-sectional area of ​​the open container.

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