Microfluidic chip, holder and pre-crosslinked gel particle displacement percolation experiment method
By using microfluidic chips and a clamping system, the percolation structure can be adjusted to adapt to different gel particle properties. Combined with a visualization system, the problem of visualizing the percolation law and blocking mechanism of pre-crosslinked gel particles in porous media is solved, realizing the repeatability and comparability of experiments and reducing resource waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DAQING OILFIELD CO LTD
- Filing Date
- 2024-12-16
- Publication Date
- 2026-06-16
AI Technical Summary
In existing indoor displacement flow experiments, the flow patterns and microscopic plugging mechanisms of pre-crosslinked gel particles in porous media are difficult to visualize and characterize. Furthermore, the differences in the pore structure of real core samples lead to poor experimental repeatability and comparability, resulting in wasted resources and unreliable experimental results.
By employing microfluidic chips and grippers, and adjusting the size and combination of the inlet, outlet, and pore throat, displacement permeation experiments are conducted using a visualization system. Dynamic images of gel particles are acquired, enabling visualization of microscopic permeation patterns and blocking mechanisms. The chip can be reused for multiple experiments.
This study visualized the permeation patterns and blocking mechanisms of pre-crosslinked gel particles in porous media, ensuring the consistency and repeatability of experimental conditions, reducing experimental costs, and improving the comparability of experimental results.
Smart Images
Figure CN122209501A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the technical field of tertiary oil recovery and micro-displacement oil mechanism and plugging mechanism research, specifically to the chip, holder and usage method of pre-crosslinked gel particle displacement seepage experiment. Background Technology
[0002] The statements in this section provide only background information in connection with this disclosure and do not constitute prior art.
[0003] In studies of tertiary oil recovery and microscopic oil displacement mechanisms and plugging mechanisms, laboratory displacement experiments are typically used to evaluate the seepage patterns and microscopic plugging mechanisms of pre-crosslinked gel particles in porous media. Currently, when conducting displacement seepage experiments, the core is placed in a core holder, and the macroscopic plugging effect of the pre-crosslinked gel particles on the core interior can only be judged by observing the pressure curve changes during the displacement process. However, cores from the same batch with the same permeability exhibit significant differences in pore structure characteristics such as pore radius, throat radius, and pore-throat combination, resulting in a lack of comparability and poor repeatability in parallel experiments.
[0004] In addition, the cores are discarded after the displacement experiment because the pre-crosslinked gel particles are sheared and broken, adsorbed and retained, and transported with reservoir minerals in the porous medium during the displacement process. The internal pore structure of the core changes, making the cores unusable, resulting in resource waste and affecting the evaluation effect.
[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention
[0006] In view of this, this disclosure provides a microfluidic chip, a holder, and a method for displacement flow experiments using pre-crosslinked gel particles. This solves the problems of existing indoor displacement flow experiments where pre-crosslinked gel particles cannot be reused after being tested on rock cores, the inability to visualize the microscopic flow patterns and blocking processes of gel particles in pores of different sizes, and the significant differences in the pore structure characteristics of real rock cores, which make it impossible to ensure the consistency of rock core conditions during indoor experiments and thus make it impossible to compare and analyze the experimental results.
[0007] To achieve the above-mentioned objectives, in a first aspect, the microfluidic chip includes:
[0008] A visible chip body and cover plate, wherein the cover plate is bonded to the chip body;
[0009] The cover plate is provided with a seepage inlet and a seepage outlet. On the chip body, at least two channels are provided between the seepage inlet and the seepage outlet. Adjacent channels are connected in series through throats. The seepage inlet and the seepage outlet are connected in series with adjacent channels. The channels and the throats constitute the pore-throat structure of the rock core.
[0010] In this disclosure and possible embodiments, the dimensions of each pore and each throat are determined based on the particle size, swelling factor, compressive strength, and elasticity factor of the pre-crosslinked gel particles.
[0011] In this disclosure and possible embodiments, the method for determining the dimensions of the seepage inlet, seepage outlet, each channel, and each throat is as follows:
[0012] When the pre-crosslinked gel particles have a particle size of less than 0.15 mm, a swelling ratio of 3, an elasticity factor of 6.2, and a compressive strength of 1.0 MPa, the throat diameter is 0.3 or 0.2 mm.
[0013] When the pre-crosslinked gel particles have a particle size of 0.15–0.30 mm, a swelling ratio of 4, an elasticity factor of 6.5, and a compressive strength of 1.2 MPa, the throat diameter is 0.3 or 0.4 mm.
[0014] When the pre-crosslinked gel particles have a particle size of 0.30–0.50 mm, a swelling ratio of 5, an elasticity factor of 7.1, and a compressive strength of 1.4 MPa, the throat diameter is 0.4 or 0.5 mm.
[0015] When the pre-crosslinked gel particles have a particle size greater than 0.50 mm, a swelling ratio of 6, an elasticity factor of 7.3, and a compressive strength of 1.5 MPa, the throat diameter is 0.5 or 0.6 mm.
[0016] In this disclosure and possible embodiments, the chip body and cover plate are made of ultra-white glass.
[0017] In this disclosure and possible embodiments, the chip body and the cover plate are square.
[0018] Secondly, the chip holder includes:
[0019] The upper clamping plate and the lower clamping plate are provided. The lower clamping plate has a chip groove in its center. The depth of the chip groove is less than the thickness of the microfluidic chip described in any one of the first inventions. The upper clamping plate and the lower clamping plate are fixed around their perimeter by bolts.
[0020] Thirdly, the displacement percolation experimental method for the pre-crosslinked gel particles includes:
[0021] After fixing the microfluidic chip described in any of the first aspects in the chip holder described in the second aspect, it is connected to the microscopic visualization displacement system for displacement percolation experiments.
[0022] In this disclosure and possible embodiments, in the microscopic visualization displacement system, a stereo microscope is used in conjunction with a high-speed camera or a high-speed industrial camera to acquire high-definition images of the dynamic process of pre-crosslinked gel particles blocking pores of different sizes.
[0023] In this disclosure and possible embodiments, the microfluidic chip is vacuumed before being placed in the chip holder for fixation.
[0024] In this disclosure and possible embodiments, the pre-crosslinked gel particles are stained and then connected to the microscopic visualization displacement system for displacement percolation experiments.
[0025] In this disclosure and possible embodiments, after the displacement percolation experiment, the channels of the microfluidic chip are cleaned with water. If dye and gel particles remain in the channels after rinsing with water, a diluted solution of hydrogen peroxide solution with ammonia or soda ash is used for cleaning. After cleaning, vacuuming and drying are performed.
[0026] The beneficial effects of this invention are as follows:
[0027] The microfluidic chip of this invention can adapt to the seepage characteristics of pre-crosslinked gel particles with different particle sizes, swelling ratios, elastic factors, and compressive strengths within the pores by adjusting the size and combination of the seepage inlet, seepage outlet, each pore, and each series throat. By acquiring dynamic images of the movement of gel particles within the pore throats, the microscopic seepage law, sealing mechanism, and adjustment mechanism of pre-crosslinked gel particles in porous media can be revealed. The microfluidic chip can be reused after thorough cleaning for multiple experiments, solving the problems of inconsistent experimental conditions and increased experimental costs due to core waste. Attached Figure Description
[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.
[0029] Figure 1-1 This is a schematic diagram of the front structure of the microfluidic chip according to an embodiment of the present disclosure;
[0030] Figure 1-2 for Figure 1-1 Schematic diagram of the central channel and throat;
[0031] Figure 2This is a schematic diagram of the longitudinal cross-section of a microfluidic chip according to an embodiment of this disclosure;
[0032] Figure 3 This is a schematic diagram of the front structure of the microfluidic chip and chip holder combined according to an embodiment of the present disclosure;
[0033] Figure 4 This is a longitudinal cross-sectional view of the microfluidic chip and chip holder combined according to an embodiment of the present disclosure;
[0034] In the diagram: chip body-1, cover plate-2, upper clamping plate-3, lower clamping plate-4, fixing bolt-5. Detailed Implementation
[0035] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.
[0036] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."
[0037] The microfluidic chip of the present invention for pre-crosslinked gel particle displacement percolation experiments includes a chip body and a cover plate, wherein the cover plate and the chip body are connected by bonding technology; a percolation inlet and a percolation outlet are provided on the cover plate; on the chip body, corresponding to the percolation inlet and the percolation outlet, at least two channels are provided between them, and adjacent channels are connected in series through throats; the percolation inlet and the percolation outlet are respectively connected in series with adjacent channels; because the channels and the throats constitute the pore-throat structure of the core, they can replace the core for pre-crosslinked gel particle displacement percolation experiments.
[0038] The dimensions of each channel and throat on the chip body are customized according to parameters such as the particle size, swelling factor, compressive strength and elasticity factor of the pre-crosslinked gel particles to meet the requirements of different experimental conditions.
[0039] The pre-crosslinked gel particles can have their particle size, swelling factor, elasticity factor, compressive strength, and other parameters adjusted according to the pore size. Simultaneously, the pore size of the microfluidic chip can also be adjusted based on the performance parameters of the pre-crosslinked gel particles, achieving a perfect match between the gel particles and the microfluidic chip and ensuring the success rate of the experiment. The matching relationship between the chip's pore size and the performance of the pre-crosslinked gel particles is shown in Table 1.
[0040] Table 1. Matching Relationship between Chip Channel Size and Pre-crosslinked Gel Particle Performance
[0041]
[0042] In this disclosure, the chip body and cover plate are square and made of ultra-white glass. Because the chip body and cover plate are thermally bonded at high temperature, the internal pore throat structure will not change due to external factors. Therefore, it can be used for various corrosive fluids and can be reused multiple times. When conducting pre-crosslinked gel particle displacement permeation experiments, the pore throat size and type combination of the microfluidic chip can be designed according to the performance parameters such as the particle size, swelling factor, elasticity factor and compressive strength of the gel particles. This helps to study the microscopic permeation law and microscopic plugging mechanism of pre-crosslinked gel particles in porous media. It is applicable to the research fields of oil exploration and development and chemical flooding enhanced oil recovery principles and technologies.
[0043] In this disclosure, the preferred microfluidic chip uses high-strength, temperature-resistant, pressure-resistant, and corrosion-resistant ultra-white glass with a light transmittance of 91.7%.
[0044] In this disclosure, a stereomicroscope is preferably used in conjunction with a high-speed camera or a high-speed industrial camera in a microscopic visualization displacement system to acquire high-definition images of the dynamic process of pre-crosslinked gel particles blocking pores of different sizes. This effectively solves the problem that real core displacement and seepage experiments cannot visualize the seepage pattern of pre-crosslinked gel particles inside the pore throat structure.
[0045] In this disclosure, when studying the microscopic permeation law and microscopic blockage mechanism of pre-crosslinked gel particles in porous media, a chip holder used in conjunction with the microfluidic chip is required. The chip holder includes an upper clamping plate and a lower clamping plate. A chip groove is opened in the center of the lower clamping plate. The depth of the chip groove is less than the thickness of the microfluidic chip. The upper clamping plate and the lower clamping plate are fixed around their perimeter by bolts.
[0046] The following are preferred embodiments of this disclosure.
[0047] like Figure 1-1 , 1-2As shown, in this embodiment, the microfluidic chip has a chip body 1 and a cover plate 2 that are squares of 45.0mm*45.0mm. The diameters of the inlet and outlet on the cover plate 2 are both 3mm. On the chip body 1, a first channel, a second channel, a third channel, and a fourth channel are provided between the inlet and the outlet. The diameters of the first channel, the second channel, the third channel, and the fourth channel are all 3mm. The left inlet of the first channel is connected to the inlet, and the inlet diameter is 0.5mm. The right outlet of the fourth channel is connected to the outlet, and the outlet diameter is 0.5mm. The first channel, the second channel, the third channel, and the fourth channel are connected through throats. The right side of the first channel is connected in series with the first throat, which has a diameter of 0.4mm. The left side of the second channel is connected in series with the first throat, and the right side is connected in series with the second throat, which has a diameter of 0.3mm. The left side of the third channel is connected in series with the second throat, and the right side is connected in series with the third throat, which has a diameter of 0.2mm. The left side of the fourth channel is connected in series with the third throat.
[0048] like Figure 2 As shown, the total thickness of the microfluidic chip body 1 and the cover plate 2 in this embodiment is 4.0 mm.
[0049] like Figure 3 and Figure 4 As shown, in this embodiment, the chip holder has upper clamp 3 and lower clamp 4, both measuring 60.0mm*60.0mm*6.0mm. The chip groove depth at the center of the lower clamp 4 is 2.0mm. The microfluidic chip of this embodiment is placed into the chip groove, and the fixing bolts 5 between the upper clamp 3 and the lower clamp 4 are locked. The microfluidic chip is fixed in the chip holder. After the microfluidic chip is fixed by the chip holder, a displacement percolation experiment is carried out to study the microscopic blockage mechanism of pre-crosslinked gel particles.
[0050] The following describes a displacement percolation experiment using the microfluidic chip and holder of this invention. This experiment, conducted using a preferred embodiment of the microfluidic chip and holder, investigates the dynamic process of pre-crosslinked gel particles with diameters of 0.15–0.30 mm as they pass through the 0.5 mm, 0.4 mm, 0.3 mm, and 0.2 mm throats of the microfluidic chip shown in Figure 1. The microscopic percolation behavior, blocking mechanism, and adjustment mechanism are analyzed by considering changes in performance parameters such as particle size, swelling factor, elasticity factor, and compressive strength of the pre-crosslinked gel particles. The specific displacement percolation experiment process is as follows:
[0051] 1. Before the experiment, determine the performance parameters such as the particle size, swelling ratio, compressive strength and elasticity factor of the pre-crosslinked gel particles to ensure that the fully swollen gel particles can move within the microfluidic chip.
[0052] 2. A vacuum pump is used to evacuate the microfluidic chip, which is then placed in a holder for fixation. The chip is then connected to a microscopic visualization displacement system, using water for displacement. A constant-speed mode is employed, with displacement rates set at 0.003 ml / min, 0.01 mL / min, and 0.05 mL / min, using variable-speed, variable-flow displacement at an injection volume of 20 PV. Displacement continues until no air bubbles or impurities remain within the microfluidic chip. Finally, the vacuum pump is connected, and the chip is evacuated until all moisture is drained. The microfluidic chip is then placed in a 45°C drying oven for further drying.
[0053] 3. Soak pre-crosslinked gel particles with a particle size of 0.15 mm to 0.3 mm in deionized water at a concentration of 500 mg / L. Stir with a glass rod for 2 minutes and let stand for 5 minutes. After the pre-crosslinked gel particles have completely swollen, add methylene blue staining agent and let stand for 5 minutes to allow the staining agent to fully penetrate the swollen pre-crosslinked gel particles.
[0054] 4. Place the stained pre-crosslinked gel particles into an intermediate container and connect it to a microscopic visualization displacement system. First, purge the air from the pipeline and valves at a rate of 5 mL / min. Once gel particles are seen flowing out of the outlet section of the injection pipeline, set the displacement rate to 0.003 mL / min. Use a high-speed industrial camera to capture dynamic transport images of pre-crosslinked gel particles of different sizes within series pores of different throat diameters. Set the image capture interval to 1 second. Analyze the dynamic images to reveal the seepage patterns and microscopic blocking mechanisms of the pre-crosslinked gel particles within series pores of different sizes.
[0055] 5. After the displacement experiment, the microfluidic chip was rinsed with water at a high flow rate of 0.5 mL / min for a displacement time greater than 20 PV. Even after rinsing, a small amount of staining agent and gel particles remained in the channels. These were removed by diluting hydrogen peroxide with water at a 1:5 ratio, adding a few drops of ammonia or sodium carbonate solution, and then heating the diluted solution appropriately. Once no pre-crosslinked gel particle fragments or methylene blue staining agent remained in the microfluidic chip channels, a vacuum pump was connected to evacuate the chip, removing all water. The chip was then placed in a 45°C drying oven for further drying, ready for future use.
[0056] As can be seen from the above displacement percolation experiment, this invention combines a microfluidic chip with a microscopic visualization displacement system. First, the microfluidic chip is processed and thermally bonded with high-strength ultra-white glass, which has high light transmittance and can withstand high temperature, high pressure and corrosion from various chemical agents. By adjusting the dimensions of the percolation inlet, percolation outlet, each pore and throat, it can adapt to the percolation characteristics of pre-crosslinked gel particles with different particle sizes, swelling ratios, elastic factors and compressive strengths in the pores. That is, the size and type of the pores inside the microfluidic chip can be customized according to experimental requirements and actual reservoir characteristics, thereby simulating the blocking process of pre-crosslinked gel particles under different reservoir pore structure characteristics.
[0057] Secondly, a stereomicroscope combined with a high-speed camera can be used to acquire high-definition images, enabling visualization studies of the process of sealing, compression, deformation, passage, and transport of individual gel particles.
[0058] Finally, after the experiment is completed, thorough cleaning allows for repeated experiments, ensuring consistent experimental conditions and comparable results.
[0059] Therefore, by conducting displacement permeation experiments on pre-crosslinked gel particles using the microfluidic chip of this invention, it is convenient to reveal the permeation law and blockage mechanism of pre-crosslinked gel particles in porous media, providing technical support for the research and development and performance evaluation of chemical flooding post-oil displacement systems.
[0060] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A microfluidic chip, characterized in that, include: A visible chip body and cover plate, wherein the cover plate is bonded to the chip body; The cover plate is provided with a seepage inlet and a seepage outlet. On the chip body, at least two channels are provided between the seepage inlet and the seepage outlet. Adjacent channels are connected in series through throats. The seepage inlet and the seepage outlet are connected in series with adjacent channels. The channels and the throats constitute the pore-throat structure of the rock core.
2. The microfluidic chip according to claim 1, characterized in that: The dimensions of each pore and throat are determined based on the particle size, swelling ratio, compressive strength, and elasticity factor of the pre-crosslinked gel particles.
3. The microfluidic chip according to claim 2, characterized in that, The method for determining the dimensions of each channel and each throat is as follows: When the pre-crosslinked gel particles have a particle size of less than 0.15 mm, a swelling ratio of 3, an elasticity factor of 6.2, and a compressive strength of 1.0 MPa, the throat diameter is 0.3 or 0.2 mm. When the pre-crosslinked gel particles have a particle size of 0.15~0.30mm, a swelling ratio of 4, an elasticity factor of 6.5, and a compressive strength of 1.2MPa, the throat diameter is 0.3 or 0.4mm. When the pre-crosslinked gel particles have a particle size of 0.30~0.50mm, a swelling ratio of 5, an elasticity factor of 7.1, and a compressive strength of 1.4MPa, the throat diameter is 0.4 or 0.5mm. When the pre-crosslinked gel particles have a particle size greater than 0.50 mm, a swelling ratio of 6, an elasticity factor of 7.3, and a compressive strength of 1.5 MPa, the throat diameter is 0.5 or 0.6 mm.
4. The microfluidic chip according to any one of claims 1-3, characterized in that: The chip body and cover plate are made of ultra-white glass with a light transmittance of 91.7%.
5. The microfluidic chip according to claim 4, characterized in that: The chip body and the cover plate are square.
6. A chip holder, characterized in that, include: The upper clamping plate and the lower clamping plate are provided. The lower clamping plate has a chip groove in its center. The depth of the chip groove is less than the thickness of the microfluidic chip according to any one of claims 1-5. The upper clamping plate and the lower clamping plate are fixed around their perimeter by bolts.
7. A displacement percolation experimental method for pre-crosslinked gel particles, characterized in that, include: Place the microfluidic chip according to any one of claims 1-5 into the chip holder according to claim 6. After being fixed in the holder, it is connected to the microscopic visualization displacement system for displacement and seepage experiments.
8. The displacement percolation experimental method for pre-crosslinked gel particles according to claim 7, characterized in that: The microscopic visualization displacement system utilizes a stereo microscope in conjunction with a high-speed camera or high-speed... Industrial cameras are used to capture high-resolution images of the dynamic process of pre-crosslinked gel particles sealing within pores of different sizes.
9. The displacement percolation test method for pre-crosslinked gel particles according to claim 7 or 8, characterized in that: Before placing the microfluidic chip into the chip holder for fixation, the microfluidic chip... The film is subjected to vacuum treatment.
10. The displacement percolation experimental method for pre-crosslinked gel particles according to claim 9, characterized in that: The pre-crosslinked gel particles, after being stained, are incorporated into the microscopic visualization displacement system. The displacement seepage experiment was conducted.
11. The displacement percolation experimental method for pre-crosslinked gel particles according to claim 10, characterized in that: After the displacement permeation experiment, the channels of the microfluidic chip are cleaned with water. If dye and gel particles remain in the channels after rinsing with water, a diluted solution of hydrogen peroxide solution with ammonia or soda ash is used for cleaning. After cleaning, vacuum treatment and drying are performed.