Micro-fluidic chip for visualized research on flow of sand prevention fluid and manufacturing method of micro-fluidic chip

Abstract

The invention relates to a micro-fluidic chip for visually researching flow of sand prevention fluid and a manufacturing method, and belongs to the field of micro-fluid and petrochemical industry. The chip comprises a chip main body, a liquid inlet device, a liquid receiving device and an observation recording device. The micro-fluidic chip is formed by sealing two layers of transparent glass plates, sand grains with specific properties are filled between the glass plates, and a liquid inlet and a liquid outlet are formed in the two ends of the chip. The liquid inlet device is a microfluid injection pump, the liquid receiving device can be connected with different pressure environments, and the observation recording device is composed of a microscope, a high-speed camera and a computer. The manufacturing method comprises the steps of determining the spatial position of the glass plate, sealing glue, filling sand grains, connecting the liquid inlet device and the liquid receiving device and the like. The device is simple in structure, convenient to manufacture, low in cost and high in precision, the flow can be controlled to simulate various sand prevention conditions, the real flowing conditions of sand prevention or other fluid can be observed in situ, and the microscopic flowing state of the sand prevention fluid flowing in a rock stratum and the wetting process between the fluid and the rock stratum in the actual process can be visually researched.

Description

Technical Field

[0001] The invention relates to a microfluidic chip for visually studying the flow of sand-control fluid and a manufacturing method thereof, and belongs to the fields of microfluids and petrochemical industry. Background Art

[0002] The sand production problem is a challenging problem in the process of oil reservoir exploitation. Sand production can cause safety hazards, such as wellbore blockage, underground collapse, production shutdown, sand accumulation in separation equipment, and even fire hazards. The current sand control methods are mainly divided into two categories: mechanical sand control methods and chemical sand control methods. The chemical sand control method is to inject chemical sand control agents into the formation through a pumping process to change the formation properties, prevent the generation of sand particles and block the transportation process. The chemical sand control agents currently used include fluids such as epoxy resins, porous resins, polymer gels and nanoparticle solutions.

[0003] At present, the research on the effect of chemical sand control mainly analyzes the macroscopic properties such as the overall pressure drop and permeability of the rock formation after using the sand control agent in the formation. The microscopic mechanism of the sand control agent is not clear, and the research results have large deviations and poor universality. The lack of in-situ dynamic observation research methods for the microscopic flow state of the sand control agent fluid flow in the rock formation, the wetting process between the fluid and the rock formation, and the microstructural changes of the rock formation has seriously restricted the research and development of chemical sand control.

[0004] In view of the problem that the action process of the above-mentioned sand control fluid cannot be dynamically observed in situ, the present invention proposes a plate-type microfluidic chip. The chip is composed of two transparent glass plates encapsulated with a certain distance between the plates. As needed, sand particles of specific size and morphology are filled in the chip to simulate the actual properties of the rock formation for sand control. The sand control fluid flows into one end of the chip and flows out from the other end. Under a microscope, the flow action process of the sand control fluid in the rock formation can be observed in situ, and the fluid flow process is recorded with the help of a camera for analyzing the action mechanism of the sand control fluid. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a microfluidic chip which has a simple structure, is easy to manufacture, has good visualization effect, and can be used in a variety of sand control conditions, and a manufacturing method thereof.

[0006] The innovation of the present invention lies in the use of a new type of microfluidic chip structure, which can solve the problem that the existing devices are unable to perform in-situ dynamic observation of the action process of sand control fluid during the chemical sand control process, and are unable to obtain the microscopic flow state of sand control fluid, the wetting process of rock formation, and the dynamic changes of rock formation microstructure.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A microfluidic chip for visualizing the flow of sand control fluid, the microfluidic chip comprising a chip body, a liquid inlet device, a liquid receiving device and an observation and recording device.

[0009] The chip body includes a liquid inlet, a liquid outlet and a flow observation area. One end of the liquid inlet is connected to the liquid inlet device, and the other end is connected to the flow observation area; one end of the liquid outlet is connected to the flow observation area, and the other end is connected to the liquid receiving device.

[0010] Further, the liquid inlet and the liquid outlet are located at the central positions at both ends of the flow observation area, and their positions are directly opposite to ensure that the flow of the sand control fluid does not deviate perpendicular to the flow direction.

[0011] Further, the flow observation area is formed by encapsulating upper and lower transparent glass plates, sand grains are filled between the plates, and the periphery is sealed with glue, and only the liquid inlet and the liquid outlet are left to allow the sand control fluid to pass through.

[0012] The liquid inlet device is a microfluidic injection pump, which can precisely control the feeding flow rate, simulate the flow at different flow velocities, and observe the flow of the sand control agent at different flow velocities.

[0013] The liquid receiving device is currently directly connected to the atmosphere, and can also be connected to environments with different pressures to simulate the flow under pressurized conditions.

[0014] The observation and recording device includes a microscope, a high-speed camera and a computer. The microscope and the high-speed camera are connected to the computer, and the flow process of the sand control fluid in the microfluidic chip system is observed and photographed in situ through the microscope and the high-speed camera, and the data is recorded by the computer.

[0015] A manufacturing method of a microfluidic chip for visualizing the flow of sand control fluid, comprising the following implementation steps:

[0016] Step 1: Overlap and place two transparent glass plates of the same specification, and sandwich spacers with different thicknesses in the middle to determine the thickness between the plates. The thickness between the plates is between 10 μm and 1000 μm.

[0017] Step 2: Use sealing glue to completely seal the gap between the two transparent glass plates in the length direction, and wait for the glue to cure and have a certain supporting strength.

[0018] Step 3: After the glue is fixed, take out the spacer, horizontally insert a thin tube in the middle of one side in the width direction of the transparent glass plate for connecting the liquid inlet device, fix the thin tube with glue, ensure that one end of it is connected to the liquid inlet device outside the microfluidic chip device, and the other end penetrates into the flow observation area. The sand control fluid can smoothly enter the flow observation area from the thin tube under the drive of the liquid inlet device.

[0019] Step 4: Use sealing glue to completely seal the gap between the boards on one side of the thin tube in step 3, and wait for the glue to solidify and have a certain supporting strength.

[0020] Step 5: After the glue is cured, fill the other side of the transparent glass plate in the width direction with sand particles. Slightly shake the filling process to ensure that the filling process is even and there are no obvious gaps between the sand particles.

[0021] Step 6: After filling is completed, insert a thin tube horizontally from the other side in the width direction to connect to the liquid receiving device, and fix the thin tube with glue to ensure that one end of the tube is connected to the flow observation area and the other end is connected to the liquid receiving device. Driven by the pressure difference, the fluid can enter the liquid receiving device from the flow observation area.

[0022] Step 7: Use sealing glue to completely seal the gap between the boards on one side of the thin tube in step 6, and wait for the glue to solidify and have a certain supporting strength.

[0023] Step 8: After the glue is completely cured, the device body is connected to the liquid inlet device and the liquid receiving device through thin tubes, wherein the thin tube connected to the liquid inlet device serves as the liquid inlet, and the thin tube connected to the liquid receiving device serves as the liquid outlet.

[0024] Step 9: Place the microfluidic chip on a microscope stage connected to a high-speed camera, adjust the flow rate of the sand control fluid, and observe and record the flow of the sand control fluid.

[0025] Preferably, in step 2, glue with high viscosity, high strength and good sealing effect is selected.

[0026] Preferably, in step 5, the oscillation process has a stable speed and a stable rhythm, and machine oscillation can be selected.

[0027] Preferably, the observation and recording device in step 9 is an optical microscope with a high frame rate and adjustable magnification.

[0028] Preferably, the material, shape and size of the glass plate, the material and size of the needle, the type and size of the sand particles, the type of sand control agent, etc. used in the experiment can be selected according to actual conditions.

[0029] Compared with the existing device, the present invention has the following beneficial effects:

[0030] (1) The microfluidic chip of the present invention has a simple device structure, is easy to manufacture, and has low material cost, but has high observation accuracy. The microfluidic liquid inlet device can accurately control the feed flow rate and simulate the flow of sand control fluid under different conditions.

[0031] (2) The present invention has a wide range of manufacturing flexibility and can replace different liquid inlet devices, liquid receiving devices, transparent glass plate materials, shapes and sizes, and types and models of observation and recording devices; and in addition to sand control fluids, it can also be used to observe the flow state of other types of fluids; the flow of fluids under different conditions can be measured and observed by pre-treating raw materials, changing environmental conditions, applying external force fields, etc.

[0032] (3) The present invention can observe the actual flow of fluid in situ, which can make up for the defect that the sand control fluid action process cannot be observed in situ during the experiment of the existing device, and solve the problem that the microscopic flow state of the sand control fluid material flowing in the rock formation, the wetting process between the fluid and the rock formation, and the dynamic changes of the microstructure of the rock formation are not visible during the actual flow process. The microscopic flow state of the sand control fluid material flowing in the rock formation and the wetting process between the fluid and the rock formation during the actual flow process can be visualized for research, and can also be used for in situ observation of other fluid flow processes, which is of great significance for studying the action mechanism of sand control fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the operation of the microfluidic chip; (a) is a flow chart of the experimental device, and (b) is an enlarged schematic diagram of the microfluidic chip structure.

[0034] Figure 2 Flow patterns of two sand control materials: epoxy resin and silica nano solution; Figure (a 1 ) is the epoxy resin flow state 1; Figure (a 2 ) is the epoxy resin flow state 2; Figure (a 3 ) is the epoxy resin flow state 3; Figure (a 4 ) is the epoxy resin flow state 4; Figure (b 1 ) is the flow state 1 of the silica nano-solution sand control material; Figure (b 2 ) is the flow state 2 of the silica nano-solution sand control material; Figure (b 3 ) is the flow state 3 of the silica nano-solution sand control material; Figure (b 4 ) is the flow state 4 of the silica nano solution sand control material.

[0035] Figure 3 Figure 2 is a microscopic process diagram of the flow, adsorption and film formation of the nano-solution sand-control material; Figure (a) is the microscopic flow state 1 of the nano-solution sand-control material; Figure (b) is the microscopic flow state 2 of the nano-solution sand-control material; Figure (c) is the microscopic flow state 3 of the nano-solution sand-control material; Figure (d) is the microscopic flow state 4 of the nano-solution sand-control material. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below.

[0037] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meanings commonly used in the art.

[0038] In the description of the present invention, it needs to be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "one end", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] In the description of the present invention, unless otherwise specified and limited, the terms "provided with", "equipped with", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or connected through an intermediate medium.

[0040] In addition, for the sake of convenience of explanation, the drawings of the specification appropriately show various components to be larger or smaller, and do not show the actual sizes of the embodiments of the present disclosure.

[0041] Example 1

[0042] The operation steps of this embodiment are as follows:

[0043] Step 1: Select two rectangular transparent silica glass plates with a length of 76 mm, a width of 25 mm, and a thickness of 1 mm. Place an elastic plastic sheet with a length of 100 mm, a width of 10 mm, and a thickness of 500 μm in the same direction in the middle of the two glass plates. Use spring clips to fix the glass plate and the plastic sheet to ensure that no relative sliding occurs during operation.

[0044] Step 2: Use a glass rod to dip in epoxy resin glue, and evenly apply a layer of epoxy resin glue on both sides of the glass plate in the length direction. Allow the glue to penetrate into the gap between the plates through capillary action. Ensure that the depth of the glue between the glass plates is between 2mm and 3mm. The thickness of the glue applied on both sides is consistent. Do not touch the glass plate and the plastic sheet during the application process to avoid relative sliding. After checking that there is no leakage in the seals on both sides, wait for 2 hours until the glue solidifies and has a certain strength, then remove the spring clip and pull out the plastic sheet.

[0045] Step 3: Insert a metal needle with an outer diameter of 300μm, an inner diameter of 200μm, and a length of 10mm into the horizontal center of one side of the width direction of the glass plate. The length of the needle inside and outside the plate is 5mm. Apply a layer of epoxy resin glue around the contact between the middle section of the needle and the outer edge of the glass plate, fix the needle, wait for 30 minutes until the glue solidifies to the point that the needle will not shake, and then continue to apply a layer of epoxy resin glue on this width side. The glue penetrates into the gap between 2mm and 3mm through capillary action. After checking that one side of the width is completely sealed, wait for 2 hours until the glue solidifies and has a certain strength.

[0046] Step 4: Hold the device with the unsealed side facing upwards with a spring clip, and use a fine funnel to add quartz sand of 40-60 meshes. Add until there is a 2mm distance between the upper edge of the quartz sand and the outer edge of the glass plate, remove the device and shake it slightly to eliminate the gaps between the quartz sand, and then repeat this process until the position of the quartz sand does not change after shaking. At this time, it is considered that the quartz sand is evenly filled in the chip body.

[0047] Step 5: Insert a metal needle with an outer diameter of 300μm, an inner diameter of 200μm, and a length of 10mm in the horizontal center of one side in the width direction where the quartz sand is added. The length of the needle inside and outside the plate is 5mm. Apply a layer of epoxy resin glue around the contact between the middle section of the needle and the outer edge of the glass plate, fix the needle, wait for 30 minutes until the glue solidifies to the point that the needle will not shake, and then continue to apply a layer of epoxy resin glue on this width side. The glue enters the gap between 2mm and 3mm through capillary action. After checking that one side of the width is completely sealed, wait for 12 hours until all the glue is completely solidified.

[0048] Step 6: A flexible slender plastic tube with an inner diameter of 300 μm and a length of 400 mm is respectively nested on the needles on both sides. The inlet plastic tube is connected to a 20 ml syringe with a needle, and the syringe is installed on the microfluidic injection pump; the outlet plastic tube is connected to the liquid receiving device.

[0049] Step 7: Place the device horizontally on the operating table and install the observation and recording device directly above the device.

[0050] Step 8: Turn on the recording device. Since epoxy resin A is a transparent solution, add a small amount of indigo dye epoxy resin A into the syringe for easy observation. Adjust the injection flow rate of the microfluidic injection pump to 100 μl / min. Record the flow morphology after the injection starts, and take a real-time photo with a camera every 1 second until the flow ends. Replace the syringe with one filled with epoxy resin B immediately after the injection is completed, keep the injection flow rate of the microfluidic injection pump unchanged, record the flow morphology after the injection starts, and take a real-time photo every 1 second until the flow ends, and record the flow time throughout the process.

[0051] Step 9: After the epoxy resin observation is completed, the image is processed to obtain a flow pattern change over time graph, as shown in the attached figure. Figure 2 As shown in (a): the orange area is the area where epoxy resin A flows, and the yellow area is the area where epoxy resin B flows; obviously, the flow front of epoxy resin B is extremely uneven, resulting in low coverage and material utilization of the sand control agent, showing an obvious "flow fingering phenomenon".

[0052] Example 2

[0053] The operation steps of this embodiment are as follows:

[0054] Step 1: Repeat steps 1 to 6 of Example 1 to prepare multiple microfluidic chips with the same specifications.

[0055] Step 2: Place the device horizontally on the operating table and install the observation and recording device directly above the device.

[0056] Step 3: Turn on the recording device. Since the nano-solution sand-proof material is a colorless and transparent solution, add a small amount of methyl orange dye to the solution and shake it fully to make the solution colored for easy observation. Adjust the injection flow rate of the microfluidic injection pump to 100 μl / min. The concentration of silica nanoparticles in the nano-solution sand-proof material used is 30%. Shake the nano-solution fully before injection to prevent precipitation. Record the flow morphology after the injection begins. Take a real-time photo with a camera every 1 second until the flow ends, and record the flow time throughout the process.

[0057] Step 4: After the observation and recording of the nano-solution sand control material is completed, the picture is processed to obtain the flow pattern change over time, as shown in the attached figure. Figure 2 As shown in (b): The yellow area is the area where the nano-solution sand control material flows. Compared with traditional resin materials, the nano-solution has better uniformity and higher coverage, can reach all positions evenly without obvious resistance, and eliminates the "flow fingering phenomenon".

[0058] Step 5: Place another microfluidic chip under an optical microscope, add 30% concentration of silica nano-solution sand control material into a 20 ml syringe, and adjust the injection flow rate of the microfluidic injection pump to 100 μl / min.

[0059] Step 6: Adjust the magnification of the optical microscope to four to forty times, and adjust the position of the device to a position where the field of view is clear and the particles are evenly distributed.

[0060] Step 7: Before injection, shake the nano solution thoroughly to prevent precipitation. After the injection begins, record the flow morphology through an optical microscope, record the flow time throughout the process, and process and analyze the images through a computer.

[0061] Step 8: All records are completed, and the observation results are as follows Figure 3 As shown: Figures (a) to (d) show the adsorption process of nanoparticles on the surface of quartz sand grains when the silica nanosolution flows through the gaps between quartz sand grains: initially, there are large gaps between the quartz sand grains. As the nanosolution flows, the nanoparticles flow through these gaps and continuously attach and gather on the surface of the quartz sand. As the solution continues to flow, the nanoparticles on the surface of adjacent quartz sand grains eventually grow and connect together to form a bridging structure between the grains. At the same time, since the bridging structures formed by the nanoparticles are mainly located at the junctions of the sand grains, these bridging structures will not significantly change the pore space structure of the sand grains, and therefore will not have a significant impact on the permeability of the rock formation, and ensure the integrity of the formation sand control consolidation.

[0062] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A microfluidic chip for visualizing the flow of sand control fluids, characterized in that: The microfluidic chip comprises a chip body, a liquid inlet device, a liquid receiving device and an observation and recording device; The chip body comprises a liquid inlet, a liquid outlet and a flow observation area, wherein one end of the liquid inlet is connected to the liquid inlet device and the other end is connected to the flow observation area; one end of the liquid outlet is connected to the flow area and the other end is connected to the liquid receiving device; The liquid inlet device can accurately control the feed flow rate, simulate the flow at different flow rates, and observe the flow of the sand control agent at different flow rates; The liquid receiving device includes a liquid receiving pipe and a liquid receiving container, which are used to hold the outflowing sand control solution and can be connected to different pressure environments; The observation and recording device includes a microscope, a high-speed camera, and a computer; the microscope, the high-speed camera, and the computer are connected to perform in-situ observation and photography of the sand-proof fluid flow process in the microfluidic chip system through the microscope and the high-speed camera; the computer is used to control the high-speed camera, store picture and video data, and analyze the flow conditions.

2. A microfluidic chip for visualizing the flow of sand control fluid according to claim 1, characterized in that: The liquid inlet device is a microfluid injection pump of different specifications.

3. A microfluidic chip for visualizing the flow of sand control fluid according to claim 1, characterized in that: The liquid inlet and the liquid outlet are located at the center positions of both ends of the flow observation area.

4. A microfluidic chip for visualizing the flow of sand control fluid according to claim 1, characterized in that: The flow observation area is composed of upper and lower transparent glass plates, with sand filled between the plates and sealed around with glue, leaving only a liquid inlet and a liquid outlet for passing sand-proof fluid.

5. A microfluidic chip for visualizing the flow of sand control fluid according to claim 4, characterized in that: The thickness between the upper and lower transparent glass plates is 10 μm-1000 μm.

6. A method for manufacturing a microfluidic chip for visualizing the flow of sand control fluid according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Place two transparent glass plates of the same specifications on top of each other, and place spacers of different thicknesses between the glass plates to adjust the thickness between the plates; Step 2: Use sealing glue to completely seal the gap between the two transparent glass plates in the length direction; Step 3: Remove the spacer and insert a thin tube as the liquid inlet tube connected to the liquid inlet device; Step 4: Completely seal the gap between the plates on one side of the capillary tube in step 3; Step 5: After the glue is cured, fill the other side of the transparent glass plate in the width direction with sand; Step 6: After filling, insert another thin tube as the liquid outlet tube connected to the liquid receiving device; Step 7: Use glue to completely seal the gap between the boards on one side of the capillary tube in step 6; Step 8: After the glue is completely cured, connect the liquid inlet device and the liquid receiving device through a thin tube; Step 9: After the chip is manufactured, place the chip in the observation area of ​​the observation and recording device, adjust the flow of the pumping device, and observe and record the flow of the sand control fluid.

7. The method for manufacturing a microfluidic chip for visualizing the flow of sand control fluid according to claim 6, characterized in that: The step 3 is specifically as follows: after the glue is fixed, the spacer is removed, a thin tube is horizontally inserted into the middle of one side in the width direction of the transparent glass plate, and the thin tube is fixed with glue. The sand-proof fluid can smoothly enter the flow observation area from the thin tube under the drive of the liquid inlet device.

8. The method for manufacturing a microfluidic chip for visualizing the flow of sand control fluid according to claim 6, characterized in that: The step 6 is specifically as follows: after the filling is completed, a thin tube is horizontally inserted from the other side in the width direction, and the thin tube is fixed with glue, so that the fluid can enter the liquid receiving device from the flow observation area driven by the pressure difference.

9. The method for manufacturing a microfluidic chip for visualizing the flow of sand control fluid according to claim 6, characterized in that: In the step 5, the sand is fully shaken during the filling process to ensure the uniformity of the sand filling.

10. The method for manufacturing a microfluidic chip for visualizing the flow of sand control fluid according to claim 6, characterized in that: In step 4, the filling sand type may be a single type of sand, or may be a mixture of multiple sands, a layered filling of multiple sands, or other methods, to simulate complex formation conditions and flow conditions in formation contact areas at different depths.

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