Porous medium seepage experiment device

Abstract

The porous medium seepage experiment device comprises a water injection system, a spiral seepage system, a water return system and a monitoring system, the spiral seepage system comprises a central seepage inlet, a porous structure, a spiral partition plate, an annular fluid collecting tank, a seepage outlet, a bottom plate and a top plate, and a channel area defined by the spiral partition plate, the bottom plate and the top plate is a spiral channel. The annular fluid collecting groove is formed in the outer side of the spiral partition plate, and the spiral channel is filled with the porous structure. According to the invention, the condition of local concentration or non-uniform distribution of the fluid in the initial stage of seepage is avoided, and the fluid is also prevented from being concentrated at one outlet to flow out, so that the fluid is more fully contacted with the porous medium, and the seepage efficiency and non-uniformity are improved.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic rock seepage, and in particular relates to a porous medium seepage experimental device. Background Art

[0002] Carbon dioxide geological storage is one of the important measures to achieve carbon emission reduction. Its storage capacity, efficiency and safety are closely related to geological conditions. In carbon dioxide geological storage, one of the key technologies is to use the porous characteristics of rock structure to achieve capillary capture. Due to the randomness and heterogeneity of rock fracture pores, the capillary capture mechanism of carbon dioxide is still unclear, which hinders the further development of carbon dioxide geological storage related technologies. In order to analyze the impact of pore structure disorder on carbon dioxide capillary capture efficiency, it is often necessary to conduct porous media seepage simulation experiments indoors.

[0003] Existing porous media seepage test devices often use direct current channels at the boundaries, without fully considering the complexity and heterogeneity of rock porous media, resulting in a short seepage path and a single flow state. In addition, the contact time between the fluid and the porous medium is short, and the interaction efficiency is low, making it difficult to simulate the real fluid flow environment and fluid complexity in nature. Summary of the invention

[0004] Purpose of the invention: In order to overcome the problems that the existing porous medium seepage test device does not fully consider the complexity and heterogeneity of rock porous media, and the contact time between fluid and porous media is short and the interaction efficiency is low, the present invention provides a porous medium seepage test device.

[0005] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A porous medium seepage experimental device, comprising a water injection system, a spiral seepage system, a water return system and a monitoring system;

[0007] The water injection system is used to provide a constant pressure water flow to the spiral seepage system.

[0008] The spiral seepage system includes a central seepage inlet, a porous structure, a spiral partition, an annular fluid collecting groove, a seepage outlet, a bottom plate and a top plate, wherein the bottom plate and the top plate are arranged opposite to each other, the spiral partition is arranged between the bottom plate and the top plate, and the channel area surrounded by the spiral partition, the bottom plate and the top plate is a spiral channel. The annular fluid collecting groove is arranged outside the spiral partition, the seepage inlet is arranged at the center of the bottom plate, the seepage outlet is arranged outside the annular fluid collecting groove, and the seepage outlet is connected to the annular fluid collecting groove. The porous structure is filled in the spiral channel.

[0009] The water return system is used to collect water flow from the outlet of the spiral seepage system.

[0010] The monitoring system is used to monitor the pressure and flow changes of the seepage channel in the spiral seepage system.

[0011] Preferably, the polar coordinate equation of the spiral line of the spiral partition is as follows:

[0012]

[0013] Among them, r is the radius coordinate of any point P on the curve, a is a constant, θ represents the angle of any point P on the curve, α 0 is the initial angle between the tangent vector at point P and the line connecting the center of the circle, k is the number of spiral coils, and Δα is the change in the angle between the tangent vector at point P and the line connecting the center of the circle.

[0014] Preferably: the spiral partition expands outward from the central entrance to form a main flow channel, and the spiral partition is provided with openings at certain angles as secondary flow channels, and the secondary flow channels are used to connect the main flow channel on the inner side of the spiral partition spiral with the main flow channel on the outer side of the spiral partition spiral.

[0015] Preferably, the porous structure is obtained by an expansion method to obtain a tightly packed disc structure, and then the disc size is randomly reduced by a specified multiple to obtain a porous structure. The throat size of the porous structure obeys a Gaussian distribution.

[0016] Preferably, the upper and lower surfaces of the porous structured disk are fixed to the top plate and the bottom plate respectively by anchor bolts and strong glue.

[0017] Preferably, the water injection system comprises a submersible pump, a pressure tank, and a water storage tank. The submersible pump is arranged at the bottom of the water storage tank. The submersible pump is connected to the inlet of the pressure tank through a pipe 1. A check valve is arranged in the middle of the pipe 1 between the submersible pump and the pressure tank. The outlet of the pressure tank is connected to the central fluid inlet of the spiral seepage system through a pipe 1.

[0018] Preferably: the pressure tank is provided with an exhaust valve, and a valve is provided on a pipe between the pressure tank and the spiral seepage system.

[0019] Preferably, the water return system comprises a second pipe, one end of which is connected to the total seepage outlet (205), one end of which is away from the total seepage outlet (205) is immersed in the water storage tank, and a second valve is provided on the second pipe.

[0020] Preferably, the monitoring system comprises a host computer, a pressure sensor 1, an electromagnetic flowmeter, a pressure sensor 2, and a pressure sensor 3, wherein the pressure sensor 1 is arranged on the pressure tank, the electromagnetic flowmeter and the pressure sensor 2 are arranged on the pipe 1 between the pressure tank and the spiral seepage system, and the pressure sensor 3 is arranged on the spiral channel. The host computer is respectively connected to the pressure sensor 1, the electromagnetic flowmeter, the pressure sensor 2, and the pressure sensor 3 for communication.

[0021] Preferably, the spiral partition has openings at intervals of 45° as secondary flow channels.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The spiral seepage channel of the present invention adopts a flow pattern of central inlet and peripheral outlet to diffuse the seepage to the surrounding areas, which not only avoids the local concentration or uneven distribution of the fluid that may occur in the early stage of seepage, but also avoids the fluid concentrating and flowing out at one outlet, so that the fluid can be more fully in contact with the porous medium, thereby improving the efficiency and non-uniformity of the seepage.

[0024] 2. The spiral seepage system of the present invention adopts a spiral channel. The fluid does not flow along a straight line or a simple curve, but moves along a spiral trajectory, has a longer seepage path, and the channel size continues to expand, and the flow inside the seepage channel is in a decelerated state. As the channel width gradually increases, the fluid has more space to diffuse and flow, which can simulate the expanding seepage path in geological conditions.

[0025] 3. The spiral channel of the spiral seepage system of the present invention has holes at intervals of 45 degrees to form a secondary flow channel. The pressure of the secondary flow channel is greater than that of the main flow channel, and the water flows into the main flow channel at a certain angle. The injection of secondary flow intensifies the collision and mixing of fluid particles, and the flow velocity and pressure in the mixing zone are more uneven, thereby making the flow state more complex and diverse, and closer to the real flow environment in the rock cracks and pores in the formation.

[0026] 4. The seepage inlet pressure of the present invention is adjustable, and the seepage characteristics of porous media under different pressure conditions can be obtained, and the real flow environment in rock fracture pores in strata at different depths can be simulated, which has universal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall layout diagram of the porous medium seepage experimental device of the present invention.

[0028] Figure 2 It is a schematic diagram of the spiral seepage system of the present invention.

[0029] Figure 3 It is a schematic diagram of the porous medium installation mold of the present invention.

[0030] Figure 4 It is a side schematic diagram of the porous medium installation mold of the present invention.

[0031] Description of reference numerals: Description of reference numerals:

[0032] 100-water injection system, 101-submersible pump, 102-check valve, 103-pressure tank, 104-exhaust valve, 105-valve, 106-water injection pipe, 107-water storage tank, 200-spiral seepage system, 201-central seepage inlet, 202-porous structure, 203-spiral partition, 2031-opening, 204-annular fluid collecting groove, 205-seepage outlet, 206-bottom plate, 207-top plate, 208-spiral channel, 209-temporary limit plate, 300-backwater system, 301-water outlet pipe, 302-valve, 400-monitoring system, 401-electromagnetic flowmeter, 4021-pressure sensor one, 4022-pressure sensor two, 4023-pressure sensor three. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0034] A porous medium seepage experimental device, such as Figure 1-4 As shown, it includes a water injection system 100 , a spiral seepage system 200 , a water return system 300 and a monitoring system 400 .

[0035] The water injection system 100 is used to provide a constant-pressure water flow to the spiral seepage system 200. The water injection system 100 can provide a constant-pressure water flow to the spiral seepage system.

[0036] The water injection system 100 includes a submersible pump 101, a pressure tank 103, and a water tank 107. The submersible pump 101 is arranged at the bottom of the water tank 107. The submersible pump 101 is connected to the inlet of the pressure tank 103 through a pipe 106. A check valve 102 is arranged in the middle of the pipe 106 between the submersible pump 101 and the pressure tank 103.

[0037] The outlet of the pressure tank 103 is connected to the central fluid inlet 201 of the spiral seepage system 200 through a pipe 106 .

[0038] The pressure tank is provided with a pressure sensor 4021 and an exhaust valve 104 , and the pipeline 106 between the pressure tank 103 and the spiral seepage system 200 is provided with a valve 105 , an electromagnetic flowmeter 401 and a pressure sensor 4022 .

[0039] The spiral seepage system 200 is used to form a spiral seepage channel and has an irregularly arranged pore structure.

[0040] like Figure 2 As shown, the spiral seepage system 200 includes a central seepage inlet 201, a porous structure 202, a spiral partition 203, an annular fluid collection groove 204, a seepage outlet 205, a bottom plate 206 and a top plate 207. The bottom plate 206 and the top plate 207 are arranged opposite to each other, and the spiral partition 203 is arranged between the bottom plate 206 and the top plate 207. The area surrounded by the spiral partition 203, the bottom plate 206 and the top plate 207 is a spiral channel 208. The spiral partition 203 expands outward from the central inlet to form a main flow channel. The spiral partition 203 is provided with openings 2031 at intervals of a certain angle as secondary flow channels. In another embodiment, an opening 2031 is provided at intervals of 45° as a secondary flow channel. The secondary flow channel is used to connect the main flow channel on the inner side of the spiral partition 203 with the main flow channel on the outer side of the spiral partition 203, so as to form an interference flow with the main flow channel. The pressure of the secondary flow channel is greater than that of the main flow channel, and the water flow is injected into the main flow channel at a certain angle. The injection of secondary flow intensifies the collision and mixing of fluid particles, and the velocity and pressure in the mixing zone are more uneven, so that the flow state is more complex and diverse, and closer to the real flow environment in the rock fracture pores in the formation. The annular fluid collecting groove 204 is arranged on the outside of the spiral partition 203, and the innermost side of the annular fluid collecting groove 204 is evenly provided with seepage holes, which serve as seepage holes and flow along the water collecting groove 204 to the total outlet 205. The seepage inlet 201 is arranged at the center of the bottom plate 206, and the seepage outlet 205 is arranged at the end of the entire seepage system 200, and the seepage outlet 205 is connected to the annular fluid collecting groove 204. The seepage outlet 205 is arranged on the outside of the annular fluid collecting groove 204, and the seepage outlet 205 is connected to the annular fluid collecting groove 204. The porous structure 202 is filled in the spiral channel 208.

[0041] The polar coordinate equation of the spiral line of the spiral partition 203 is as follows:

[0042]

[0043] Among them, r is the radius coordinate of any point P on the curve, a is a constant, θ represents the angle of any point P on the curve, α 0 is the initial angle between the tangent vector at point P and the line connecting the center of the circle, α 0 =(80±3.5)°, k is the number of spiral coils, Δα is the change in the angle between the tangent vector at point P and the line connecting the center of the circle, and the value range is Δα=(1±0.5)°.

[0044] Initial angle α0 The expansion range of the spiral line is determined by the angle change Δα. The initial angle α 0 If the spiral radius is too large, it will expand slowly. If it is too small, the radius will expand quickly. The initial angle α 0 The value of 80°±3.5° makes the maximum radius of the spiral vary between 50m and 500mm. The angle variation Δα can regulate the expansion rate of the radius of each turn of the spiral. Its value should make the spiral radius increase continuously and the expansion rate be between 2-4 times. Initial angle α 0 When the angle change Δα is within this range, the expansion of the spiral is relatively smooth, which helps to optimize the flow path of the fluid and make the fluid flow more smoothly on the surface of the object.

[0045] In the spiral channel formed by the spiral partition 203, the fluid does not flow along a straight line or a simple curve, but moves along a spiral trajectory, has a longer seepage path, and the channel size continues to expand, and the flow inside the seepage channel is in a decelerated state. As the channel width gradually increases, the fluid has more space to diffuse and flow, which can simulate the expanding seepage path in geological conditions.

[0046] like Figure 3 , 4 As shown, the porous structure 202 is designed using two-dimensional discrete element software, and a densely packed disc structure is obtained by an expansion method, and then the disc size is randomly reduced by a specified multiple to obtain a porous structure. The throat size of the porous structure 202 obeys a Gaussian distribution.

[0047] After obtaining the position of the disc, the mold of the porous structure 202 and its temporary limiting plate 209 is printed out using 3D printing technology, and then the disc is filled into the mold. The upper and lower surfaces of the disc are fixed to the top plate 207 and the bottom plate 206 respectively by anchor bolts and strong glue to prevent movement.

[0048] The porous structure 202 obtains a tightly packed disc structure by the expansion method, and then randomly reduces the disc size by a specified multiple to obtain a porous structure. The disc size is reduced by different multiples to make it obey the Gaussian random distribution, so that the pore throat size is also a non-uniform Gaussian distribution. By regulating the non-uniform distribution of the pore throat size, the seepage characteristics and mechanism of the porous medium are comprehensively analyzed.

[0049] The water return system 300 is used to collect water flow from the outlet of the spiral infiltration system 200 .

[0050] The return water system 300 includes a second pipe 301 , one end of which is connected to the main seepage outlet ( 205 ), and one end of the second pipe 301 away from the main seepage outlet ( 205 ) is immersed in the water storage tank 107 . A second valve 302 is provided on the second pipe 301 .

[0051] The monitoring system 400 is used to monitor the pressure and flow changes of the seepage channel.

[0052] The monitoring system 400 includes a host computer, a pressure sensor 1 4021, an electromagnetic flowmeter 401, a pressure sensor 2 4022, and a pressure sensor 3 4023. The pressure sensor 1 4021 is arranged on the pressure tank, the electromagnetic flowmeter 401 and the pressure sensor 2 4022 are arranged on the pipe 1 106 between the pressure tank 103 and the spiral seepage system 200, and the pressure sensor 3 4023 is arranged on the spiral channel 208. The host computer is respectively connected to the pressure sensor 1 4021, the electromagnetic flowmeter 401, the pressure sensor 2 4022, and the pressure sensor 3 4023 for communication.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A porous medium seepage experimental device, characterized in that: It includes a water injection system (100), a spiral seepage system (200), a water return system (300) and a monitoring system (400): The water injection system (100) is used to provide a constant pressure water flow to the spiral seepage system (200); The spiral seepage system (200) comprises a central seepage inlet (201), a porous structure (202), a spiral baffle (203), an annular fluid collecting groove (204), a seepage outlet (205), a bottom plate (206) and a top plate (207), wherein the bottom plate (206) and the top plate (207) are arranged opposite to each other, and the spiral baffle (203) is arranged between the bottom plate (206) and the top plate (207), and the spiral baffle (203), the bottom plate (206) and the top plate (207) are arranged opposite to each other. The channel area enclosed by the plates (207) is a spiral channel (208); the annular fluid collecting groove (204) is arranged outside the spiral partition plate (203); the seepage inlet (201) is arranged at the center of the bottom plate (206); the seepage outlet (205) is arranged outside the annular fluid collecting groove (204), and the seepage outlet (205) is connected to the annular fluid collecting groove (204); the porous structure (202) is filled in the spiral channel (208); The water return system (300) is used to collect water flow from the outlet of the spiral seepage system (200); The monitoring system (400) is used to monitor the pressure and flow changes of the seepage channel in the spiral seepage system (200).

2. The porous medium seepage experimental device according to claim 1, characterized in that: The polar coordinate equation of the spiral line of the spiral partition (203) is as follows: Where r is the radius coordinate of any point P on the curve, a is a constant, θ represents the angle of any point P on the curve, α0 is the initial angle between the tangent vector at point P and the line connecting the center of the circle, k is the number of spiral coils, and Δα is the change in the angle between the tangent vector at point P and the line connecting the center of the circle.

3. The porous medium seepage experimental device according to claim 2, characterized in that: The spiral partition (203) expands outward from the central entrance to form a main flow channel. The spiral partition (203) is provided with openings (2031) at certain angles as secondary flow channels. The secondary flow channels are used to connect the main flow channel on the inner side of the spiral partition (203) with the main flow channel on the outer side of the spiral partition (203).

4. The porous medium seepage experimental device according to claim 3, characterized in that: The porous structure (202) is obtained by an expansion method to obtain a tightly packed disc structure, and then the disc size is randomly reduced by a specified multiple to obtain a porous structure; the throat size of the porous structure (202) obeys a Gaussian distribution.

5. The porous medium seepage experimental device according to claim 4, characterized in that: The upper and lower surfaces of the circular disk of the porous structure (202) are respectively fixed to the top plate (207) and the bottom plate (206) by anchor bolts and strong glue.

6. The porous medium seepage experimental device according to claim 5, characterized in that: The water injection system (100) comprises a submersible pump (101), a pressure tank (103), and a water storage tank (107). The submersible pump (101) is arranged at the bottom of the water storage tank (107). The submersible pump (101) is connected to the inlet of the pressure tank (103) through a pipe (106). A check valve (102) is arranged in the middle of the pipe (106) between the submersible pump (101) and the pressure tank (103). The outlet of the pressure tank (103) is connected to the central fluid inlet (201) of the spiral seepage system (200) through the pipe (106).

7. The porous medium seepage experimental device according to claim 6, characterized in that: The pressure tank is provided with an exhaust valve (104), and a valve (105) is provided on a pipe (106) between the pressure tank (103) and the spiral seepage system (200).

8. The porous medium seepage experimental device according to claim 7, characterized in that: The return water system (300) comprises a second pipe (301), one end of which is connected to the main seepage outlet (205), and one end of which is away from the main seepage outlet (205) is immersed in the water storage tank (107). A second valve (302) is arranged on the second pipe (301).

9. The porous medium seepage experimental device according to claim 8, characterized in that: The monitoring system (400) comprises a host computer, a pressure sensor 1 (4021), an electromagnetic flowmeter (401), a pressure sensor 2 (4022), and a pressure sensor 3 (4023); the pressure sensor 1 (4021) is arranged on a pressure tank; the electromagnetic flowmeter (401) and the pressure sensor 2 (4022) are arranged on a pipe 1 (106) between the pressure tank (103) and the spiral seepage system (200); and the pressure sensor 3 (4023) is arranged on a spiral channel (208); the host computer is respectively connected to the pressure sensor 1 (4021), the electromagnetic flowmeter (401), the pressure sensor 2 (4022), and the pressure sensor 3 (4023) for communication.

10. The porous medium seepage experimental device according to claim 1, characterized in that: The spiral partition (203) has openings (2031) at intervals of 45° as secondary flow channels.

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