Porous medium multiphase flow experimental device and method under different microbial amounts

Abstract

This invention discloses an experimental apparatus and method for multiphase flow in porous media under different microbial biomass conditions. The apparatus includes a seepage column, an overflow tank, a fluid assembly, and a measurement assembly. The seepage column has multiple sampling holes and pressure measuring holes on its peripheral sidewalls, an outlet on its top wall, and an inlet on its bottom wall. The overflow tank is connected to the outlet at the top of the seepage column. The fluid assembly is connected to the inlet via a peristaltic pump and includes a first chamber for containing the aqueous phase, a second chamber for containing the non-aqueous phase, and a third chamber for containing the biofilm. The measurement assembly includes multiple pressure measuring tubes, a differential pressure sensor, a first flow meter located between the first chamber and the seepage column, a second flow meter located between the second chamber and the seepage column, a colony counter located between the third chamber and the seepage column, a total organic carbon analyzer connected to multiple sampling holes, and multiple viscosity sensors located at the inlet and outlet. Each pressure measuring tube corresponds to one pressure measuring hole and is connected to the differential pressure sensor. The apparatus dynamically regulates microbial growth and monitors multiphase flow parameters in real time.

Description

Technical Field

[0001] This invention relates to the field of porous media multiphase flow experimental technology, specifically to an experimental apparatus and method for porous media multiphase flow under different microbial quantities. Background Technology

[0002] In the study of multiphase flow in porous media, the constitutive relationship between saturation (S) and relative permeability (kr) is a core dynamic parameter. Its accurate quantification is of key significance for theoretical research and engineering practice in fields such as environmental remediation, oil extraction, and groundwater pollution control.

[0003] In traditional studies, constitutive equations typically consider only two- or three-phase flows of non-aqueous liquids (NAPL), water, and gas, neglecting the dynamic effects of the microbial membrane phase. When microorganisms grow and metabolize in porous media, the formation and growth of the microbial membrane can lead to microbial blockage. Furthermore, the periodic shedding of microorganisms causes repeated blockage and unblocking of pore spaces, dynamically altering the pore structure, porosity, and tortuosity of the porous medium. Moreover, gases and organic acids produced by microbial metabolism change the physicochemical properties of the fluid, significantly affecting saturation distribution. Simultaneously, microbial growth influences the nonlinear permeation of fluids in porous media, thereby affecting the relative permeability of the fluid.

[0004] In the existing technology, there is a lack of experimental devices that can dynamically regulate the growth state of microorganisms and accurately quantify their impact. This makes it difficult for traditional modeling methods to clarify the intrinsic relationship between saturation, relative permeability, microbial biomass, and non-Darcy effect, and thus cannot accurately describe the multiphase flow dynamics process under the influence of microorganisms. Summary of the Invention

[0005] The main objective of this invention is to provide an experimental apparatus and method for multiphase flow in porous media under different microbial quantities, in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention proposes an experimental apparatus for multiphase flow in porous media under different microbial biomass, comprising: A seepage column extends vertically and contains a porous medium and multiple pore plates. The multiple pore plates are spaced apart along the vertical direction. The peripheral sidewall of the seepage column has multiple sampling holes and multiple pressure measuring holes, which are spaced apart along the vertical direction. The top wall of the seepage column has an outlet, and the bottom wall of the seepage column has an inlet. An overflow tank is located at the top of the seepage column and is connected to the outlet so that the fluid in the seepage column can be discharged into the overflow tank. A fluid assembly, connected to the inlet via a peristaltic pump, includes a first tank, a second tank, and a third tank. The first tank contains an aqueous phase, the second tank contains a non-aqueous phase, and the third tank contains a biofilm. The measurement assembly includes multiple pressure measuring tubes, a differential pressure sensor, a first flow meter, a second flow meter, a colony counter, a total organic carbon analyzer, and multiple viscosity sensors. The multiple pressure measuring tubes are correspondingly arranged with the multiple pressure measuring holes and connected to the differential pressure sensor to measure the pressure difference along the fluid flow path for calculating the fluid seepage velocity. The first flow meter is located between the first housing and the seepage column to measure the flow rate of the aqueous phase. The second flow meter is located between the second housing and the seepage column to measure the flow rate of the non-aqueous phase. The colony counter is located between the third housing and the seepage column to measure the number of microorganisms in the biofilm. The total organic carbon analyzer is connected to the multiple sampling holes to detect the content of microbial metabolic organic matter in the fluid. The viscosity sensors are respectively located at the inlet and the outlet to detect the viscosity of the fluid.

[0007] Optionally, the measurement component further includes multiple pH / redox potential composite sensors, with the pH / redox potential composite sensors respectively installed in the middle of the seepage column and at the outlet, for detecting changes in the pH value and redox potential of the fluid.

[0008] A filter is provided at each of the pressure measuring holes.

[0009] Optionally, the first and second chambers are respectively equipped with pH adjustment devices to adjust the pH value of the aqueous / non-aqueous phase.

[0010] Optionally, the side pressure hole is provided with three, including an upper pressure measuring hole, a lower pressure measuring hole and a middle pressure measuring hole. The upper pressure measuring hole is located near the top wall of the seepage column, the lower pressure measuring hole is located near the bottom wall of the seepage column, and the middle pressure measuring hole is located at the middle of the seepage column. Correspondingly, there are three pressure measuring tubes.

[0011] Optionally, the bottom wall of the seepage column is provided with two water inlets, including a first water inlet and a second water inlet. The first water inlet is connected to the first box and the second box through a first water inlet pipe, and the second water inlet is connected to the third box through a second water inlet pipe. An aeration head is provided at the second water inlet.

[0012] Optionally, the peristaltic pump is provided between the first box, the second box, and the third box and the water inlet.

[0013] Optionally, the experimental apparatus for multiphase flow in porous media under different microbial quantities further includes: A heating element for heating the percolation column; and, A thermostat, electrically connected to the heating element, is used to control the temperature of the percolation column.

[0014] Optionally, the fluid assembly further includes a nutrient solution tank and an air compressor, wherein the nutrient solution tank contains nutrient solution. The third chamber is connected to the nutrient solution chamber and the air compressor, and a stirrer is installed inside the third chamber.

[0015] This invention also provides an experimental method for multiphase flow in porous media under different microbial quantities, applicable to experimental devices for multiphase flow in porous media under different microbial quantities. The experimental method for multiphase flow in porous media under different microbial quantities includes the following steps: Step S100: Fill the percolation column with porous media; Step S200: The prepared nutrient solution is introduced into the third chamber for aeration and culture to form a biofilm. The supply of the nutrient solution and the growth time are controlled to achieve dynamic regulation of microorganisms. The amount, thickness and density of microorganisms in the biofilm are recorded under different nutrient solution supply and growth time. Step S300: The aqueous phase in the first tank is introduced into the permeation column until it is completely saturated, and the initial saturation of the aqueous phase is obtained. Then, the pressure difference of multiple pressure measuring tubes is obtained through a differential pressure sensor, and the absolute permeability of the porous medium is calibrated in combination with Darcy's law. Step S400: Control the flow rate of the aqueous / non-aqueous phase using a peristaltic pump to conduct a single-phase flow experiment of the aqueous / non-aqueous phase, and monitor the flow rate, pressure, temperature, viscosity and pH value of the fluid in real time using a measuring component; Step S500: Control the flow rates of the aqueous phase and the non-aqueous phase using a peristaltic pump to conduct a two-phase flow experiment. Monitor in real time the changes in pressure, flow rate, viscosity, and fluid properties of the aqueous and non-aqueous phases at different saturations and flow rates without microbial intervention, and determine the non-Darcy permeability baseline parameters. Step S600: Pass the biofilm into the permeation column, control the microbial flow rate, pressure and frequency, observe the clogging and unblocking process of the porous medium, and record the flow rate, pressure and microbial quantity at different stages in real time. Step S700: Process experimental data, use multivariate nonlinear regression analysis, combine BCB model / VGM model for fitting analysis, establish a four-phase flow dynamic model of water-NAPL-air-biofilm, and clarify the relationship between saturation-relative permeability-microbial biomass-non-Darcy effect.

[0016] In the technical solution of this invention, the device is capable of conducting single / two-phase flow experiments and blockage-clearing kinetic experiments. By filling the seepage column with porous media, and combining peristaltic pump flow control, differential pressure sensor to measure fluid pressure difference along the flow path to calculate fluid seepage velocity, flow meter and colony counter to measure fluid flow rate for saturation calculation, relative permeability fitting and microbial biomass quantification, total organic carbon analyzer to detect the content of microbial metabolic organic matter in the fluid, and viscosity sensor to detect fluid viscosity to correct the influence of fluid viscosity on relative permeability, an integrated experimental device is constructed that can dynamically regulate microbial growth and monitor key parameters of multiphase flow in real time. Furthermore, a four-phase flow kinetic model of water-NAPL-air-biofilm is established to analyze the relationship between saturation, relative permeability, microbial biomass, and non-Darcy effect.

[0017] In the experiment, compared with the design of the seepage column which uses a pipe body for drainage, resulting in two states of Darcy and non-Darcy, and is unstable and discontinuous, thus causing errors, the present invention can ensure a stable and continuous state by using the overflow tank for drainage. In addition, the use of a differential pressure sensor for measurement and the filtering of pressure fluctuations through a moving average algorithm can solve the problem of biofilm or porous media particles clogging the pressure measuring hole at the interface between the pressure measuring pipe and the seepage column. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of an embodiment of the multiphase flow experimental apparatus for porous media under different microbial biomass provided by the present invention. Figure 2 The flowchart shows the experimental method for multiphase flow in porous media under different microbial biomass conditions provided by this invention.

[0020] Explanation of icon numbers: 100. Experimental apparatus for multiphase flow in porous media with different microbial biomass; 1. Percolation column; 11. Sampling hole; 13. First inlet; 14. Second inlet; 2. Overflow tank; 3. Fluid assembly; 31. First tank; 32. Second tank; 33. Third tank; 34. Nutrient solution tank; 35. Agitator; 4. Measuring components; 41. Pressure sensing tube; 42. Differential pressure sensor; 5. Peristaltic pump; 6. Porous plate.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] In the study of multiphase flow in porous media, the constitutive relationship between saturation (S) and relative permeability (kr) is a core dynamic parameter. Its accurate quantification is of key significance for theoretical research and engineering practice in fields such as environmental remediation, oil extraction, and groundwater pollution control.

[0026] In traditional studies, constitutive equations typically consider only two- or three-phase flows of non-aqueous liquids (NAPL), water, and gas, neglecting the dynamic effects of the microbial membrane phase. When microorganisms grow and metabolize in porous media, the formation and growth of the microbial membrane can lead to microbial blockage. Furthermore, the periodic shedding of microorganisms causes repeated blockage and unblocking of pore spaces, dynamically altering the pore structure, porosity, and tortuosity of the porous medium. Moreover, gases and organic acids produced by microbial metabolism change the physicochemical properties of the fluid, significantly affecting saturation distribution. Simultaneously, microbial growth influences the nonlinear permeation of fluids in porous media, thereby affecting the relative permeability of the fluid.

[0027] In the existing technology, there is a lack of experimental devices that can dynamically regulate the growth state of microorganisms and accurately quantify their impact. This makes it difficult for traditional modeling methods to clarify the intrinsic relationship between saturation, relative permeability, microbial biomass, and non-Darcy effect, and thus cannot accurately describe the multiphase flow dynamics process under the influence of microorganisms.

[0028] In view of this, the present invention provides an experimental apparatus 100 for multiphase flow in porous media under different microbial biomass conditions. Figure 1 This is an embodiment of the multiphase flow experimental device 100 for porous media under different microbial quantities provided by the present invention.

[0029] Please see Figure 1The multiphase flow experimental apparatus 100 for porous media under different microbial quantities includes a seepage column 1, an overflow tank 2, a fluid assembly 3, and a measuring assembly 4. The seepage column 1 extends vertically and contains porous media and multiple pore plates 6. The multiple pore plates 6 are spaced apart along the vertical direction. The peripheral wall of the seepage column 1 has multiple sampling holes 11 and multiple pressure measuring holes, which are spaced apart along the vertical direction. The top wall of the flow column 1 is provided with an outlet, and the bottom wall of the flow column 1 is provided with an inlet; the overflow tank 2 is located at the top of the flow column 1 and is connected to the outlet to allow the fluid in the flow column 1 to be discharged into the overflow tank 2; the fluid assembly 3 is connected to the inlet via a peristaltic pump 5 and includes a first tank 31, a second tank 32, and a third tank 33. The first tank 31 is used to contain the aqueous phase, the second tank 32 is used to contain the non-aqueous phase, and the third tank 3... The third chamber 33 is used to contain the biofilm. The measuring component 4 includes multiple pressure measuring tubes 41, a differential pressure sensor 42, a first flow meter, a second flow meter, a colony counter, a total organic carbon analyzer, and multiple viscosity sensors. The multiple pressure measuring tubes 41 are arranged one-to-one with the multiple pressure measuring holes and are connected to the differential pressure sensor 42 to measure the pressure difference along the fluid flow path for calculating the fluid seepage velocity. The first flow meter is located between the first chamber 31 and the seepage column 1 to measure the flow rate of the aqueous phase. The second flow meter is located between the second chamber 32 and the seepage column 1 to measure the flow rate of the non-aqueous phase. The colony counter is located between the third chamber 33 and the seepage column 1 to measure the number of microorganisms in the biofilm. The total organic carbon analyzer is connected to multiple sampling holes 11 to detect the content of microbial metabolic organic matter in the fluid. The viscosity sensors are respectively provided at the inlet and the outlet to detect the viscosity of the fluid.

[0030] In the technical solution of this invention, the device is capable of conducting single / two-phase flow experiments and blockage-clearing kinetic experiments. It uses a porous medium filled in the seepage column 1, combined with a peristaltic pump 5 for flow control, a differential pressure sensor 42 to measure the pressure difference along the fluid flow path to calculate the fluid seepage velocity, a flow meter and colony counter to measure the fluid flow rate for saturation calculation, relative permeability fitting and microbial biomass quantification, a total organic carbon analyzer to detect the content of microbial metabolic organic matter in the fluid, and a viscosity sensor to detect the fluid viscosity to correct the influence of fluid viscosity on relative permeability. This constructs an integrated experimental device capable of dynamically regulating microbial growth and real-time monitoring of key parameters of multiphase flow. Furthermore, it establishes a four-phase flow kinetic model of water-NAPL-air-biofilm, and analyzes the relationship between saturation, relative permeability, microbial biomass, and the non-Darcy effect.

[0031] During the experiment, compared to the design of the seepage column 1, which uses a pipe for drainage, resulting in two states of Darcy and non-Darcy, and is unstable and discontinuous, thus causing errors, the present invention uses the overflow tank 2 for drainage, which can ensure a stable and continuous state. In addition, the differential pressure sensor 42 is used for measurement, and the pressure fluctuation is filtered by the moving average algorithm, which can solve the problem of biofilm or porous media particles clogging the pressure measuring hole at the interface between the pressure measuring pipe 41 and the seepage column 1.

[0032] It should be noted that, in one embodiment of the present invention, the aqueous phase is deionized water and the non-aqueous phase (NAPL) is n-hexadecane.

[0033] Furthermore, the measurement component 4 also includes multiple pH / redox potential composite sensors. The pH / redox potential composite sensors are respectively installed in the middle of the seepage column 1 and at the outlet, for detecting changes in the pH value and redox potential of the fluid.

[0034] Specifically, each pressure measuring hole is equipped with a filter to prevent biofilm or porous media particles from clogging the pressure measuring hole and to ensure the continuity of pressure difference measurement along the path.

[0035] Specifically, the first chamber 31 and the second chamber 32 are respectively equipped with pH adjustment devices to adjust the pH value of the aqueous phase / non-aqueous phase, maintain the pH stability of the fluid, or simulate pH fluctuations in the natural environment.

[0036] Specifically, in one embodiment of the present invention, three pressure testing holes are provided, including an upper pressure testing hole, a lower pressure testing hole, and a middle pressure testing hole. The upper pressure testing hole is located near the top wall of the seepage column 1, the lower pressure testing hole is located near the bottom wall of the seepage column 1, and the middle pressure testing hole is located at the middle part of the seepage column 1; correspondingly, three pressure testing tubes 41 are provided.

[0037] More specifically, in one embodiment of the present invention, the upper pressure measuring hole is 20 mm away from the top wall of the seepage column 1, and the lower pressure measuring hole is 20 mm away from the bottom wall of the seepage column 1.

[0038] For details, please refer to Figure 1 The bottom wall of the seepage column 1 is provided with two water inlets, including a first water inlet 13 and a second water inlet 14. The first water inlet 13 is connected to the first box 31 and the second box 32 through a first water inlet pipe. The second water inlet 14 is connected to the third box 33 through a second water inlet pipe. An aeration head is provided at the second water inlet 14 to aerate and cultivate the nutrient solution in the third box 33, thereby regulating the nutrient supply and dissolved oxygen conditions required for microbial growth.

[0039] Specifically, the peristaltic pump 5 is provided between the first box 31, the second box 32 and the third box 33 and the water inlet.

[0040] More specifically, based on the embodiment described above, "the bottom wall of the seepage column 1 is provided with two water inlets, including a first water inlet 13 and a second water inlet 14. The first water inlet 13 is connected to the first housing 31 and the second housing 32 through a first water inlet pipe, and the second water inlet 14 is connected to the third housing 33 through a second water inlet pipe," the first water inlet pipe and the second water inlet pipe are respectively provided with the peristaltic pump 5. More specifically, the peristaltic pump 5 provided on the first water inlet pipe is a dual-channel peristaltic pump 5, model BT100M, with a speed of 0.1-600rpm and a flow accuracy of ±0.5%.

[0041] Specifically, check valves are provided between the first housing 31, the second housing 32, and the third housing 33 and the water inlet to prevent fluid backflow. More specifically, the check valves are made of PTFE and have an opening pressure ≤5kPa.

[0042] Specifically, in one embodiment of the present invention, the seepage column 1 is made of high-transmittance organic glass, with an inner diameter of 150mm ± 0.5mm and a column height of 390mm ± 1mm.

[0043] Specifically, in this invention, the distance between any two adjacent pore plates 6 is 10cm, the pore diameter of the pore plate 6 is 0.5mm, and the opening rate is 50%.

[0044] For details, please refer to Figure 1 In one embodiment of the present invention, the peripheral wall of the seepage column 1 is provided with 7 sampling holes 11 and 3 pressure measuring holes. The 7 sampling holes 11 are distributed at intervals in the vertical direction and are respectively 50mm, 100mm, 150mm, 200mm, 250mm, 300mm and 350mm away from the bottom reference surface of the seepage column 1.

[0045] Specifically, each of the sampling holes 11 is equipped with a sealing valve.

[0046] Specifically, the pressure measuring tube 41 is made of φ8mm hard glass tube.

[0047] Specifically, the multiphase flow experimental device 100 for porous media under different microbial quantities also includes a heating element and a thermostat. The heating element is used to heat the percolation column 1, and the thermostat is electrically connected to the heating element to control the temperature of the percolation column 1 and maintain it at 25±0.5℃.

[0048] More specifically, a thermometer is also provided to measure the temperature. More specifically, the heating element uses a water bath jacket heating method for uniform heating and to avoid localized overheating. The heating element is a constant temperature water bath, etc.

[0049] For details, please refer to Figure 1 The fluid assembly 3 further includes a nutrient solution tank 34 and an air compressor. The nutrient solution tank 34 contains nutrient solution. A third tank 33 is connected to the nutrient solution tank 34 and the air compressor, and a stirrer 35 is installed inside the third tank 33. Thus, the nutrient solution in the nutrient solution tank 34 is cultured using the stirrer 35 and the air compressor to obtain a biofilm.

[0050] More specifically, the nutrient solution is prepared in the ratio of glucose:NH4Cl:K2HPO4=10:1:1. The nutrient solution is introduced into the third chamber 33 for stirring and aeration to culture and obtain a biofilm. The dissolved oxygen is maintained at ≥4mg / L by turning on the air compressor, and the culture is carried out for 4-7 days until the microorganisms enter the stable growth period.

[0051] Specifically, in one embodiment of the present invention, the porous medium includes porous ceramic particles and quartz sand, and the porous ceramic particles are mixed into the quartz sand located in the middle of the seepage column 1.

[0052] It should be noted that the quartz sand should be free of dust, have intact particles, and a pH value of 6.5-7.5 (tested with pH test paper or meter). The particle size of both the quartz sand and the porous ceramic particles should be 0.2-0.5 mm.

[0053] This invention also provides an experimental method for multiphase flow in porous media under different microbial quantities, applicable to the multiphase flow experimental apparatus for porous media under different microbial quantities described above.

[0054] Please see Figure 2 The experimental method for multiphase flow in porous media under different microbial biomass includes the following steps: Step S100: Fill the percolation column with porous media.

[0055] In this step, the porous medium, namely the treated quartz sand and porous ceramic particles, is filled into the seepage column in a set ratio. During the filling process, the column is vibrated as required. After filling, the weight is measured and the length is measured. Then, the column is filled with water and weighed again to calculate the porosity.

[0056] More specifically, when filling the core growth zone of the biofilm (the 10-30cm area in the middle of the seepage column) with quartz sand, 5% porous ceramic particles are mixed in, and the remainder is filled entirely with quartz sand. During the filling process of the porous medium, every 50mm of porous medium is filled, an axial pressure of 0.1MPa is applied and vibrated for 30s to ensure porosity uniformity. The porosity is calculated by the mass difference before and after water saturation. In this way, the porosity uniformity error of the porous medium can be controlled within ±1.5%, providing a standardized medium substrate for microbial film attachment.

[0057] Furthermore, the treatment process for the quartz sand is as follows: The quartz sand is soaked in a 30% H2O2 solution for 24 hours, with 500g of quartz sand treated per liter of solution; then, the quartz sand is soaked in a 1% aminopropyltriethoxysilane solution (pH 8.0) for 2 hours; the soaked quartz sand is transferred to a sieve with a mesh size of approximately 0.1mm, and slowly rinsed with water, each rinse using enough water to cover the sand layer. After standing for 2-3 minutes, the water is drained, and the rinsing is repeated at least five times; the sand is dried in a constant temperature oven at 105℃ for 2-4 hours until a constant weight is achieved (the difference between two consecutive weighings is <0.1%); after drying, the sand is cooled to room temperature in a desiccator (approximately 30 minutes) and then sealed and stored in a dry container; the treated quartz sand must be free of dust, have intact particles, and a pH value of 6.5-7.5.

[0058] Step S200: The prepared nutrient solution is introduced into the third chamber for aeration and culture to form a biofilm. The supply of the nutrient solution and the growth time are controlled to achieve dynamic regulation of microorganisms. The amount, thickness and density of microorganisms in the biofilm are recorded under different nutrient solution supply and growth time.

[0059] In this step, the nutrient solution is prepared in a ratio of glucose:NH4Cl:K2HPO4=10:1:1 to ensure C:N:P=100:5:1.

[0060] Biofilm culture: Nutrient solution was introduced into the third chamber, and the stirrer and air compressor were turned on to maintain dissolved oxygen ≥4 mg / L for aeration culture; the OD of the bacterial culture was measured daily. 600 Before measurement, ensure the bacterial suspension is uniformly suspended to avoid sedimentation or bubbles. Use the same culture medium or buffer as the bacterial suspension as a blank control. Measure at a wavelength of 600 nm using a spectrophotometer. Repeat the measurement 2-3 times and take the average value. At the same time, record environmental parameters such as culture time, temperature, and pH value. Culture for 4-7 days until the microorganisms enter the stable growth phase.

[0061] Microbial dynamic regulation: The nutrient solution supply and growth time were controlled by gradient control of peristaltic pump to achieve dynamic regulation of microorganisms. In the early stage (1-3 days), the nutrient solution supply was 2.5L / day (≈104mL / h). In the later stage (4-7 days), it was increased to 5L / day (≈208mL / h) as the biomass increased. In the middle stage (7-20 days), it was maintained at 5-8L / day. In the later stage (21-30 days), it was reduced to 3-5L / day due to the slowdown of metabolism. The growth changes of the biofilm were observed, and relevant data such as the microbial biomass, thickness, and density of the biofilm were recorded under different nutrient supply and growth time.

[0062] More specifically, during the cultivation phase, the OD of the bacterial culture is measured daily. 600 The value was determined, and the colony counter was used to measure the number of microorganisms, thus establishing the OD value. 600 A standard curve was generated comparing the dry weight of the microorganisms. In the experiment, porous media samples of different heights were taken through the sampling holes, dried, and weighed to obtain the in-situ biofilm dry weight m. bio This is used for subsequent saturation calculations.

[0063] Step S300: The aqueous phase in the first tank is introduced into the permeation column until it is completely saturated, and the initial saturation of the aqueous phase is obtained. Then, the pressure difference of multiple pressure measuring tubes is obtained through a differential pressure sensor, and the absolute permeability of the porous medium is calibrated in combination with Darcy's law.

[0064] Step S400: Control the flow rate of the aqueous / non-aqueous phase using a peristaltic pump to conduct a single-phase flow experiment of the aqueous / non-aqueous phase, and monitor the flow rate, pressure, temperature, viscosity and pH value of the fluid in real time using a measuring component.

[0065] In this step, the flow rate is controlled by a peristaltic pump, and single-phase flow experiments of aqueous and non-aqueous phases are conducted separately. The flow rates of the aqueous and non-aqueous phases are measured by a first flow meter / second flow meter during the experiment. The fluid pressure is measured by a differential pressure sensor, the fluid viscosity at different locations is measured by a viscosity sensor, the pH value of the fluid at different locations is measured by a pH / redox potential composite sensor, and the fluid temperature is measured by a thermometer.

[0066] Step S500: Control the flow rates of the aqueous phase and the non-aqueous phase using a peristaltic pump to conduct a two-phase flow experiment. Monitor in real time the changes in pressure, flow rate, viscosity and fluid properties of the aqueous phase and the non-aqueous phase at different saturations and flow rates without microbial intervention, and determine the non-Darcy permeability baseline parameters.

[0067] In this step, the flow rates (Q) of the aqueous phase and the non-aqueous phase are controlled by a peristaltic pump. 水 :Q NAPL =9:1, or Q 水 :Q NAPL =19:1, or Q 水 :Q NAPLA two-phase flow experiment was conducted using a flow meter with a ratio of 39:1. The flow rate of the aqueous phase was measured using a first flow meter, the flow rate of the non-aqueous phase was measured using a second flow meter, the pressure of the aqueous and non-aqueous phases was measured using multiple differential pressure sensors, the viscosity of the fluid at different heights was measured using multiple viscosity sensors, the pH value of the fluid at different heights was measured using multiple pH / redox potential composite sensors, and the content of organic matter metabolized by microorganisms in the fluid at different heights was periodically measured using a total organic carbon analyzer to observe changes in fluid properties. At the same time, the fluid discharged from the seepage column, i.e., the mixed multiphase liquid, was collected through an overflow tank, and its flow rate and saturation were measured.

[0068] The Forchheimer non-Darcy flow model was used to describe fluid motion. The model parameters were calibrated by measuring pressure differences at different flow rates. The model expression is as follows: ; in, The pressure gradient along the pressure line is expressed in Pa / m. ΔP is the stable pressure difference collected in real time by the two pressure gauges, and L is the distance between the two pressure gauges. μ is the fluid viscosity, Pa·s; v is the seepage velocity, in m / s. Q is the actual flow rate measured by the flow meter, and A is the cross-sectional area of ​​the seepage column; k is the absolute permeability in m². Specifically, after the porous medium is completely saturated with water, deionized water is introduced at a constant flow rate of 1 mL / min, and the stable pressure difference ΔP is measured. The initial absolute permeability is then calibrated using Darcy's law. ρ is the fluid density, kg / m³, which is the standard density of the aqueous phase / non-aqueous phase under isothermal conditions. It can be verified offline by sampling through the sampling hole. β is the inertia coefficient m -1 This reflects the intensity of the non-Darcy effect.

[0069] Thus, based on the data obtained from the above measurements, β was obtained by nonlinear fitting using the Forchheimer non-Darcy seepage formula. Furthermore, multiple gradient flow rates ranging from 0.1 to 10 mL / min were set, and multiple sets of data (v, Simultaneously, experiments with different microbial biomass gradients were conducted to establish the correlation between β and microbial biomass and porosity.

[0070] Step S600: Pass the biofilm into the permeation column, control the microbial flow rate, pressure and frequency, observe the clogging and unblocking process of the porous medium, and record the flow rate, pressure and microbial quantity at different stages in real time.

[0071] In this step, the periodic shedding of biofilm is simulated, and the conditions (such as changing the flow rate, pressure, or adding specific chemical reagents) and frequency of biofilm shedding are controlled. The clogging and unblocking process of porous media is observed, and parameters such as flow rate, pressure, and microbial biomass are recorded in real time at different stages to provide a basis for subsequent analysis of the dynamic laws in the clogging-unblocking process and to explore the relationship between changes in microbial biomass and pore structure evolution and fluid seepage characteristics.

[0072] Step S700: Process experimental data, use multivariate nonlinear regression analysis, combine BCB model / VGM model for fitting analysis, establish a four-phase flow dynamic model of water-NAPL-air-biofilm, and clarify the relationship between saturation-relative permeability-microbial biomass-non-Darcy effect.

[0073] In this step, based on the principle of mass conservation and considering the pore volume occupied by the microbial film, a modified formula for calculating saturation is established: , ; Among them, S w This refers to the water phase saturation. S NAPL The saturation level is for the non-aqueous phase. V w The volume of the aqueous phase is m³. V NAPL The volume of the non-aqueous phase is m³. V p The total pore volume of the porous medium is m³. When filling the porous medium, the seepage column is vibrated and compacted every 50mm in height. calculate; V bio The volume of the microbial membrane is in m³. m bio For the mass of the microbial film, in kg, ρ bio The value represents the density of the microbial film, in kg / m³.

[0074] It should be noted that the cumulative injection volume is measured in real time by the flow meter, and the cumulative output volume is measured by weighing or calibrating the overflow tank. Based on the law of conservation of mass, the stagnant volume = cumulative injection volume - cumulative output volume. The uniformity of saturation distribution is verified by sampling at multiple points through multiple sampling holes.

[0075] In this way, by substituting all parameters into the calculation and subtracting the pore volume occupied by the biofilm, the true saturation in the effective pore space can be obtained, thus solving the error of traditional formulas that ignore biological blockage.

[0076] By introducing the pore blockage coefficient λ and the unblocking coefficient γ, a kinetic model of the blockage-unblocking process is established, and corrected for the non-Darcy effect: , ; Where φ is the effective porosity. V at different time points bio The calculation was simultaneously verified through pressure difference change inversion. φ0 is the initial porosity. ; t represents time, s represents the duration of microbial culture and the duration of the seepage experiment, and matches the time nodes for dynamic regulation of biofilm (1-3 days in the early stage, 7-20 days in the middle stage, and 21-30 days in the later stage); br is the relative biomass, which is the ratio of the current biofilm volume to the initial total pore volume. The gradient regulation of br is achieved by controlling the nutrient solution supply through a peristaltic pump gradient control. λ is the pore blockage coefficient, s -1 ; γ is the porosity coefficient, s -1 ; β0 is the initial inertia coefficient, m -1 Before microbial injection, the Forchheimer formula was obtained by fitting multiple flow gradient experiments; δ is the influence coefficient of microbial biomass on the non-Darcy effect. β and φ data under different br are obtained and fitted into the correction formula to quantify the degree of enhancement of the non-Darcy inertial effect by microbial growth.

[0077] Based on the corrected saturation data and the non-Darcy flow model, the formula for calculating relative permeability considering the effects of microbial biomass and nonlinear flow is derived: , ; Where, k rw The relative permeability of the aqueous phase; k r,NAPL The relative permeability of the non-aqueous phase; v w The velocity of the aqueous phase is m / s; v NAPL The velocity of the non-aqueous phase seepage is in m / s; μ w The viscosity of the aqueous phase is Pa·s; μ NAPL The viscosity of the non-aqueous phase is Pa·s; ρ w The density of the aqueous phase is kg / m³. ρ NAPL The density is for the non-aqueous phase, in kg / m³.

[0078] Using multivariate nonlinear regression analysis combined with an improved model for fitting and analysis, a four-phase flow dynamics model of water-NAPL-air-biofilm was obtained. The expression of this model is as follows: ; Where Q is the actual flow rate measured by the flow meter; A is the cross-sectional area of ​​the seepage column; ΔP is the stable pressure difference collected in real time by the two pressure measuring holes; L is the distance between the two pressure measuring holes; ρ is the fluid density, kg / m³; β is the inertia coefficient, m -1 .

[0079] In a specific embodiment of the present invention, the experimental method for multiphase flow in porous media under different microbial quantities includes the following steps: Step S100: Fill the seepage column (55cm×45cm×1.28cm) with the treated 0.2~0.5mm quartz sand and porous ceramic particles in a set ratio. Vibrate as required during filling. After filling, weigh and measure the length. Then, fill with water and weigh again. Calculate the porosity as 38.2% and the initial permeability as 1.2×10. -11 m².

[0080] Step S200: Introduce the prepared nutrient solution (mixed bacterial culture KB-1) into the third chamber for aeration culture (inoculation concentration 10). 7 A biofilm is formed using CFU / mL, and the supply of the nutrient solution and the growth time are controlled to achieve dynamic regulation of microorganisms. The amount, thickness, and density of microorganisms in the biofilm are recorded under different nutrient solution supply and growth time.

[0081] Step S300: The aqueous phase (deionized water) in the first tank is introduced into the permeation column until it is completely saturated, and the initial saturation of the aqueous phase is obtained. Then, the pressure difference of multiple pressure measuring tubes is obtained through a differential pressure sensor, and the absolute permeability of the porous medium is calibrated in combination with Darcy's law.

[0082] Step S400: Control the flow rate with a peristaltic pump to conduct single-phase flow experiments with aqueous phase (deionized water) and non-aqueous phase (oil) respectively. Measure the flow rate of the aqueous phase / non-aqueous phase during the experiment using a first flow meter / second flow meter, measure the fluid pressure using a differential pressure sensor, measure the fluid viscosity at different locations using a viscosity sensor, measure the pH value of the fluid at different locations using a pH / redox potential composite sensor, and measure the fluid temperature using a thermometer.

[0083] Step S500: Control the flow rates (Q) of the aqueous phase and non-aqueous phase using a peristaltic pump. 水 :Q NAPL=9:1, or Q 水 :Q NAPL =19:1, or Q 水 :Q NAPL A two-phase flow experiment was conducted using a flowmeter with a ratio of 39:1. The flow rate of the aqueous phase was measured using a first flowmeter, and the flow rate of the non-aqueous phase was measured using a second flowmeter. The pressure of the aqueous and non-aqueous phases was measured using multiple differential pressure sensors. The viscosity of the fluid at different heights was measured using multiple viscosity / redox potential composite sensors. The pH value of the fluid at different heights was measured using multiple pH / redox potential composite sensors. The content of organic matter metabolized by microorganisms in the fluid at different heights was measured periodically using a total organic carbon analyzer to observe changes in fluid properties. Simultaneously, the fluid discharged from the seepage column, i.e., the mixed multiphase liquid, was collected through an overflow tank, and its flow rate and saturation were measured. In other words, the pressure, flow rate, viscosity, and fluid property changes of the water-oil two-phase flow without microbial intervention were determined at different saturations (aqueous phase saturation 30%~70%, oil phase saturation 30%~70%) and different flow rates (0.5~5 mL / min). Then, the Forchheimer equation was fitted to determine the non-Darcy permeability baseline parameters.

[0084] Step S600: The biofilm is introduced into the seepage column, and the microbial flow rate, pressure and frequency are controlled. The culture is carried out continuously for 0~168h. The suspended biomass, attached biomass and biofilm thickness in the seepage column are sampled and measured periodically. At 12h, 24h, 48h, 72h and 168h of culture, the multiphase flow conditions are kept consistent, and the clogging and clearing process of the porous medium is observed. The flow rate, pressure and microbial mass of the water-oil two-phase flow at each stage are measured and recorded in real time.

[0085] Step S700: Process experimental data, apply multivariate nonlinear regression analysis, and combine BCB / VGM models for fitting analysis to establish a four-phase flow dynamics model of water-NAPL-air-biofilm. This study clarifies the relationship between saturation, relative permeability, microbial biomass, and the non-Darcy effect. Furthermore, it uses three models—Forchheimer, Seki, and Clement—to calculate permeability and compares the impact of biofilms on non-Darcy permeability characteristics.

[0086] Some experimental data are shown in the table below:

[0087] Analysis of experimental data revealed that the nutrient solution (mixed bacterial community KB-1) grew and multiplied in the two-dimensional saturated porous medium, forming a biofilm. The microbial biomass increased with increasing culture time, and the microbial biomass and biofilm thickness at the bottom of the permeation column were significantly higher than those at the top. The biofilm blocked the pores of the porous medium, leading to a decrease in the non-Darcy coefficient β of the water-oil two-phase flow and a significant drop in permeability. After 168 hours of culture, the permeability retention rate was only 11.7%, close to the 12% of the control group. The water phase saturation had a significant impact on the biofilm regulation effect, with the highest permeability retention rate at 70% water phase saturation and the lowest at 50%. The Forchheimer model prediction results best matched the actual experimental data, the Seki model was not applicable to this experimental scenario, and the Clement model predicted a larger decrease in permeability, down by 85%.

[0088] This invention provides an experimental apparatus and method for multiphase flow in porous media under different microbial biomass conditions. Breaking through the phase limitations of traditional models, it adds a biofilm phase to construct a four-phase flow system and introduces quantitative parameters related to microbial biomass, enabling a quantitative description of the influence of microorganisms on seepage, rather than a qualitative analysis. This fills a gap in the quantitative study of the impact of dynamic microbial growth. The experimental data obtained through this apparatus and method can provide a precise theoretical model foundation for multiphase flow research in porous media in fields such as environmental remediation and oil extraction, possessing significant academic value and promising engineering applications.

[0089] The experimental apparatus and method for multiphase flow in porous media under different microbial quantities provided by this invention have wide applicability. The porous media ratio, fluid type, microbial species and nutrient supply strategy can be adjusted according to different research needs. It is suitable for multiphase flow research in porous media in a variety of scenarios, and provides strong support for technological innovation and engineering optimization in related fields.

[0090] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An experimental apparatus for multiphase flow in porous media with different microbial biomass, characterized in that, The experimental apparatus for multiphase flow in porous media under different microbial biomass includes: A seepage column extends vertically and contains a porous medium and multiple pore plates. The multiple pore plates are spaced apart along the vertical direction. The peripheral sidewall of the seepage column has multiple sampling holes and multiple pressure measuring holes, which are spaced apart along the vertical direction. The top wall of the seepage column has an outlet, and the bottom wall of the seepage column has an inlet. An overflow tank is located at the top of the seepage column and is connected to the outlet so that the fluid in the seepage column can be discharged into the overflow tank. A fluid assembly, connected to the inlet via a peristaltic pump, includes a first tank, a second tank, and a third tank. The first tank contains an aqueous phase, the second tank contains a non-aqueous phase, and the third tank contains a biofilm. The measurement assembly includes multiple pressure measuring tubes, a differential pressure sensor, a first flow meter, a second flow meter, a colony counter, a total organic carbon analyzer, and multiple viscosity sensors. The multiple pressure measuring tubes are correspondingly arranged with the multiple pressure measuring holes and connected to the differential pressure sensor to measure the pressure difference along the fluid flow path for calculating the fluid seepage velocity. The first flow meter is located between the first housing and the seepage column to measure the flow rate of the aqueous phase. The second flow meter is located between the second housing and the seepage column to measure the flow rate of the non-aqueous phase. The colony counter is located between the third housing and the seepage column to measure the number of microorganisms in the biofilm. The total organic carbon analyzer is connected to the multiple sampling holes to detect the content of microbial metabolic organic matter in the fluid. The viscosity sensors are respectively located at the inlet and the outlet to detect the viscosity of the fluid.

2. The experimental apparatus for multiphase flow of porous media under different microbial biomass as described in claim 1, characterized in that the measuring component further includes multiple pH / redox potential composite sensors, and the pH / redox potential composite sensors are respectively provided in the middle of the seepage column and at the outlet, for detecting changes in the pH value and redox potential of the fluid.

3. The experimental apparatus for multiphase flow of porous media under different microbial biomass conditions as described in claim 1, characterized in that, A filter is provided at each of the pressure measuring holes.

4. The experimental apparatus for multiphase flow in porous media with different microorganism amounts according to claim 1, wherein, The first and second chambers are each equipped with a pH adjustment device to adjust the pH value of the aqueous / non-aqueous phase.

5. The experimental apparatus for multiphase flow in porous media with different microorganism amounts according to claim 1, wherein, The side pressure hole is provided with three parts, including an upper pressure measuring hole, a lower pressure measuring hole and a middle pressure measuring hole. The upper pressure measuring hole is located near the top wall of the seepage column, the lower pressure measuring hole is located near the bottom wall of the seepage column, and the middle pressure measuring hole is located at the middle of the seepage column. Correspondingly, there are three pressure measuring tubes.

6. The experimental apparatus for multiphase flow in porous media with different microorganism amounts according to claim 1, wherein, The bottom wall of the seepage column is provided with two water inlets, including a first water inlet and a second water inlet. The first water inlet is connected to the first box and the second box through a first water inlet pipe. The second water inlet is connected to the third box through a second water inlet pipe. An aeration head is provided at the second water inlet.

7. The experimental apparatus for multiphase flow in porous media with different microorganism amounts according to claim 1, wherein, The peristaltic pump is provided between the first box, the second box, and the third box and the water inlet.

8. The experimental apparatus for multiphase flow of porous media under different microbial biomass conditions as described in claim 1, characterized in that, The experimental apparatus for multiphase flow in porous media under different microbial biomass also includes: A heating element for heating the percolation column; and, A thermostat, electrically connected to the heating element, is used to control the temperature of the percolation column.

9. The experimental apparatus for multiphase flow in porous media with different microorganism amounts according to claim 1, wherein, The fluid assembly also includes a nutrient solution tank and an air compressor, wherein the nutrient solution tank contains nutrient solution. The third chamber is connected to the nutrient solution chamber and the air compressor, and a stirrer is installed inside the third chamber.

10. A method for the experiment of multiphase flow in porous media with different microorganism amounts, applicable to the experimental device for multiphase flow in porous media with different microorganism amounts according to any one of claims 1-9, characterized in that, The experimental method for multiphase flow in porous media under different microbial biomass includes the following steps: Step S100: Fill the percolation column with porous media; Step S200: The prepared nutrient solution is introduced into the third chamber for aeration and culture to form a biofilm. The supply of the nutrient solution and the growth time are controlled to achieve dynamic regulation of microorganisms. The amount, thickness and density of microorganisms in the biofilm are recorded under different nutrient solution supply and growth time. Step S300: The aqueous phase in the first tank is introduced into the permeation column until it is completely saturated, and the initial saturation of the aqueous phase is obtained. Then, the pressure difference of multiple pressure measuring tubes is obtained through a differential pressure sensor, and the absolute permeability of the porous medium is calibrated in combination with Darcy's law. Step S400: Control the flow rate of the aqueous / non-aqueous phase using a peristaltic pump to conduct a single-phase flow experiment of the aqueous / non-aqueous phase, and monitor the flow rate, pressure, temperature, viscosity and pH value of the fluid in real time using a measuring component; Step S500: Control the flow rates of the aqueous phase and the non-aqueous phase using a peristaltic pump to conduct a two-phase flow experiment. Monitor in real time the changes in pressure, flow rate, viscosity, and fluid properties of the aqueous and non-aqueous phases at different saturations and flow rates without microbial intervention, and determine the non-Darcy permeability baseline parameters. Step S600: Pass the biofilm into the permeation column, control the microbial flow rate, pressure and frequency, observe the clogging and unblocking process of the porous medium, and record the flow rate, pressure and microbial quantity at different stages in real time. Step S700: Process experimental data, use multivariate nonlinear regression analysis, combine BCB model / VGM model for fitting analysis, establish a four-phase flow dynamic model of water-NAPL-air-biofilm, and clarify the relationship between saturation-relative permeability-microbial biomass-non-Darcy effect.

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