Microscopic visualized slice for shale bedding plane flow characteristics analysis and manufacturing method thereof

Abstract

The application discloses a micro-visualization slice for shale bedding flow characteristic analysis and a manufacturing method thereof. The method can comprise the following steps: grinding a shale slice obtained by slicing a shale sample, and grinding the shale slice to a thickness of 30-40 microns; clamping the ground shale slice in the middle by using two pieces of organic glass slices with a thickness of 0.2-0.3 mm, and placing the clamped shale slice in an inlaying machine to perform hot pressing, so that the organic glass slices and the shale slice are pressed into one; drilling a hole in the radial direction of the organic glass slice by using a drill bit with a diameter of 0.7-0.9 mm, so that the hole after drilling is communicated with the shale slice; inserting one end of a quartz micron tube with an inner diameter of 0.5 mm into the hole to fix the quartz micron tube, and connecting the other end of the quartz micron tube with a quartz tube line with an inner diameter of 1.6 mm, so as to manufacture the micro-visualization slice for shale bedding flow characteristic analysis. The micro-visualization slice can lay a foundation for subsequent visualization seepage experiments of different bedding types, pressures and injection media, and clarify different beddings to shale gas reservoir flow patterns and development characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shale gas development, and particularly relates to a micro-visualization slice for shale bedding flow characteristic analysis and a manufacturing method thereof. BACKGROUND

[0002] The shale gas reservoir has obvious bedding structure, and the internal structure of the rock mass is in a lamellar or laminated form. The whole rock layer has strong anisotropy and heterogeneity. For the shale reservoir rich in bedding structure, under the influence of the complex bedding structure, the gas and water flow and the interaction make the shale micro-cracks more complex, and the bedding gas and water flow is of great significance to improve the reservoir reconstruction.

[0003] Due to the limitation of the micro-scale of the shale reservoir, the traditional shale slice cannot meet the needs of the shale reservoir bedding analysis. Many scholars use CT, scanning electron microscope and other digital processing analysis technologies to automatically identify the laminations by machines, but the identification effect depends on the difference degree of the gray values between the laminations and other minerals in the image, and the identification result is greatly affected by the heterogeneity. The basic principle is image analysis, and it is mainly aimed at the identification of the lamination type, and the lamination flow cannot be identified. For the shale bedding flow visualization device, most scholars adopt physical simulation means including sandbox simulation and glass model. The size is relatively large, the slice is relatively thick, and it is difficult to observe the bedding flow characteristics. Since the shale is very dense, if the dense core bedding flow is directly observed, the shale slice must be high, and must reach the thickness of 40 microns or even 30 microns, which has high requirements on the experimental technology. SUMMARY

[0004] In order to realize the visualization seepage experiment of different bedding types, different pressures and different injection media, analyze the flow characteristics of the gas and water fluid in the complex bedding structure of the shale bedding, and the significance to the reservoir reconstruction, and further clarify the flow mode of the shale gas reservoir and the subsequent exploration and development of different bedding, the present application provides a micro-visualization slice for shale bedding flow characteristic analysis and a manufacturing method thereof.

[0005] In the first aspect, the present application provides a manufacturing method of a micro-visualization slice for shale bedding flow characteristic analysis, which can include the following steps.

[0006] Grinding the shale slice obtained by slicing the shale sample, and grinding the shale slice to a thickness of 30-40 microns;

[0007] Using two pieces of organic glass slices with a thickness of 0.2-0.3 mm to clamp the ground shale slice in the middle, and placing it in an inlay machine for hot pressing, so that the organic glass slices and the shale slice are pressed into one body;

[0008] A hole is drilled in the radial direction of the plexiglass sheet using a drill bit with a diameter of 0.7 to 0.9 mm, so that the hole after drilling is connected to the shale sheet.

[0009] One end of a quartz microtube with an inner diameter of 0.5 mm is inserted into the hole and fixed, while the other end is connected to a quartz tube with an inner diameter of 1.6 mm to produce a microscopic visualization sheet for analyzing the flow characteristics of shale bedding.

[0010] Optionally, the grinding process of the shale sections obtained from shale sample slicing may include:

[0011] A randomly selected side of a shale section obtained from shale sample slicing is ground.

[0012] The shale thin slice with the grinding treatment is attached to a glass slide. After standing, the other side of the shale thin slice is ground by hand with the glass slide. After grinding to a thickness of 30-40 μm, it is polished with a polishing machine.

[0013] The polished shale slices and glass slides are immersed in an organic solvent to separate them. After removal, the shale slices are dried.

[0014] Optionally, grinding the shale sections may include:

[0015] Gradually use 400-mesh, 800-mesh, and 2000-mesh sandpaper for coarse grinding to achieve a surface roughness of 6.5–3.5 μm for the coarsely ground shale flakes;

[0016] The coarsely ground shale flakes are finely ground using a grinding machine to achieve a surface roughness of 1.6–0.1 μm.

[0017] Optionally, the drying conditions for drying the shale flakes are as follows: place the shale flakes in an oven at 100-105°C and dry for 24-48 hours.

[0018] Optionally, the adhesive used to bond the shale sheet and the glass slide is a resin-based adhesive;

[0019] The adhesive used to fix the quartz microtube with an inner diameter of 0.5 mm in the hole is a resin-based adhesive, and / or the adhesive used to connect the quartz microtube with an inner diameter of 0.5 mm to the quartz tubing with an inner diameter of 1.6 mm is a resin-based adhesive.

[0020] The resin adhesive is either acrylic resin adhesive or epoxy resin adhesive.

[0021] Optionally, when using resin-based adhesive to connect the quartz microtubes, the distance between the adhesive and the port of the quartz microtube should be no less than 2 mm.

[0022] Optionally, when using the resin adhesive to fix the quartz microtube, it should be fixed at room temperature for no less than 24 hours.

[0023] Optionally, the hot pressing temperature of the inlay machine is 120-130°C.

[0024] Optionally, before hot pressing using the mounting machine, the process may further include: placing a certain amount of acrylic powder into the mounting machine for hot pressing to produce an acrylic sheet with a thickness of 0.2 to 0.3 mm.

[0025] Secondly, embodiments of the present invention provide a microscopic visualization thin section, wherein the microscopic visualization thin section is manufactured according to the method for manufacturing microscopic visualization thin sections for analyzing the flow characteristics of shale bedding as described in the first aspect.

[0026] Thirdly, embodiments of the present invention provide a shale bedding flow characteristic analysis simulation system, which may include: an optical microscope, a fluid injection device, and a micro-visualization thin section manufactured based on the method for manufacturing micro-visualization thin sections for shale bedding flow characteristic analysis described in the first aspect.

[0027] The fluid injection device is connected to the quartz tubing of the micro-visualization sheet to inject fluid into the micro-visualization sheet.

[0028] The optical microscope is used to observe the layered flow characteristics of fluids in the microscopic visualization section in order to determine the flow patterns of shale gas reservoirs.

[0029] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0030] This invention provides a microscopic visualization thin section and its fabrication method for analyzing the flow characteristics of shale bedding. The fabrication method involves grinding, pressing, drilling, and connecting the sections to create a microscopic visualization thin section capable of withstanding pressures up to 2 MPa. Bedding can be clearly observed under an optical microscope. Furthermore, this microscopic visualization thin section can be directly connected to conventional shale gas experimental equipment. This lays the foundation for conducting visualization shale thin section seepage experiments with different bedding types, pressures, and injection media, clarifying the impact of different bedding types on shale gas reservoir flow patterns and development characteristics.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a flowchart of a method for fabricating microscopic visualization thin sections for analyzing the flow characteristics of shale bedding provided in an embodiment of the present invention;

[0035] Figure 2 Here is a flowchart of step S11;

[0036] Figure 3 This is a physical image of a microscopically visualized thin sheet provided in an embodiment of the present invention. Detailed Implementation

[0037] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0038] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," and "rear," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] To address the technical challenge of requiring high-quality shale thin sections (40 micrometers or even 30 micrometers thick) for direct observation of shale bedding flow in existing technologies, this invention provides a microscopic visualization thin section for analyzing shale bedding flow characteristics and its fabrication method.

[0041] Reference Figure 1 As shown in the figure, this embodiment of the invention provides a method for preparing microscopic visualization thin sections for analyzing the flow characteristics of shale bedding. The method may include the following steps:

[0042] Step S11: Grind the shale thin sections obtained from shale sample slicing to a thickness of 30-40 μm.

[0043] It should be noted that in this step, the shale sample is sliced ​​to obtain a 3cm*3cm shale thin section. This shale thin section is then used to create a microscopic visualization section, which allows for observation of the effects of different bedding types on shale gas flow characteristics and reservoir modification.

[0044] This step involves grinding the shale thin sections to achieve the desired thickness, allowing light to pass through them during the experiment and facilitating the observation of fluid flow characteristics. (Refer to...) Figure 2 As shown, the specific steps may include:

[0045] Step S111: Randomly select one side of the shale thin section obtained from the shale sample slices for grinding. In practice, this step involves: first, gradually using 400-grit, 800-grit, and 2000-grit sandpaper for coarse grinding to achieve a surface roughness of 6.5–3.5 μm for the coarsely ground shale thin section; second, using a grinding machine to finely grind the coarsely ground shale thin section to achieve a surface roughness of 1.6–0.1 μm for the finely ground shale thin section.

[0046] Step S112: Attach the ground shale slice to a glass slide, let it stand, and then hold the glass slide to grind the other side of the shale slice until the thickness reaches 30-40 μm. Then polish it with a polishing machine.

[0047] The adhesive used to bond the shale sheet and the glass slide in this step is a resin-based adhesive; specifically, it is either acrylic resin or epoxy resin. After bonding, the slide needs to stand for 12–24 hours to ensure it is firmly attached to the slide. The other side of the shale sheet is ground in the same way as in step S111 above, followed by polishing. In this embodiment, a polishing machine is used at 6000V for approximately 4 hours to achieve a smooth surface on the shale sheet.

[0048] Step S113: Immerse the polished shale slices and glass slides in an organic solvent to separate the shale slices and glass slides, and then dry the shale slices.

[0049] The organic solvent mentioned above in this step is a solvent for dissolving resin-based adhesives, such as acetone. The drying conditions for drying the shale flakes in this step are as follows: place the shale flakes in an oven at 100–105°C and dry for 24–48 hours.

[0050] Step S12: Use two pieces of plexiglass with a thickness of 0.2 to 0.3 mm to sandwich the ground shale sheet in the middle, and place it in the mounting machine for hot pressing, so that the plexiglass sheet and the shale sheet are pressed into one piece.

[0051] This step involves pressing the material into a single, integrated sheet. Before hot pressing using a mounting machine, it is necessary to prepare an acrylic sheet. This involves placing a quantity of acrylic powder into the mounting machine and hot pressing it to create an acrylic sheet with a thickness of 0.2–0.3 mm. In this embodiment, the acrylic sheet produced is a circular sheet with an inner diameter of 1.5–2 cm and a thickness of 0.2–0.3 mm. Of course, other shapes and sizes of glass sheets are also possible, and this embodiment of the invention does not impose specific limitations on them.

[0052] In this step, the hot pressing temperature of the mounting machine is 120-130℃. During the pressing process, the two pieces of acrylic glass are pressed together until they are integrated. After cooling, they are removed.

[0053] Step S13: Use a drill bit with a diameter of 0.7 to 0.9 mm to drill holes in the radial direction of the plexiglass sheet so that the drilled holes are connected to the shale sheet.

[0054] This step involves drilling. In practice, a medical dental P-type drill bit is used, with an inner diameter of less than 0.9 mm. Commonly used P-type drill bits are 0.7 mm and 0.9 mm. Other types of drill bits can also be used in this embodiment, as long as their diameter is between 0.7 and 0.9 mm and can accommodate a quartz microtube with an inner diameter of 0.5 mm. This embodiment of the invention does not impose specific limitations on this.

[0055] Step S14: Insert one end of a quartz microtube with an inner diameter of 0.5 mm into the hole and fix it, and connect the other end to a quartz tube with an inner diameter of 1.6 mm to produce a microscopic visualization thin section for analyzing the flow characteristics of shale bedding.

[0056] Reference Figure 3 As shown, the 0.5 mm quartz microtube used in this step is... Figure 3 The micron-sized tube in the middle, the 1.6mm quartz tube is Figure 3 The inlet and outlet pipelines are as follows. In this step, the adhesive used to fix the 0.5mm inner diameter quartz microtube in the hole is a resin-based adhesive, and / or, the adhesive used to connect the 0.5mm inner diameter quartz microtube to the 1.6mm inner diameter quartz pipeline is a resin-based adhesive; wherein, the resin-based adhesive is acrylic resin adhesive or epoxy resin adhesive.

[0057] Furthermore, when using resin-based adhesive to connect the quartz microtubes in this step, the distance between the adhesive and the port of the quartz microtube should be no less than 2mm. This will prevent the adhesive from clogging the port of the quartz microtube, thus preventing the fluid from being unable to be injected or discharged after blockage.

[0058] Furthermore, when using resin-based adhesive to fix the quartz microtubes in this step, they should be fixed at room temperature for no less than 24 hours.

[0059] The micro-visualized thin section fabricated using the method described above for analyzing the flow characteristics of shale bedding provided in this embodiment of the invention produces a model capable of withstanding a pressure of 2 MPa, thus enabling the visualization of seepage experiments. The inventors connected the aforementioned micro-visualized thin section to a conventional airtightness testing apparatus, saturating the shale thin section with a pressure of 1 MPa, with both the inlet and outlet circuits closed. Pressure changes were tested; if the pressure change was less than 3% within 6 hours, the shale thin section was considered to have good airtightness and could be used normally; if the pressure change was greater than 3%, the micro-visualized thin section was discarded.

[0060] The method for fabricating microscopic visualization thin sections for shale bedding flow characteristic analysis provided in this embodiment of the invention involves grinding, pressing, drilling, and connecting the sections to create a microscopic bedding visualization model (microscopic visualization thin section) that can withstand a pressure of 2 MPa. The bedding can be clearly observed under an optical microscope, and the model can be directly connected to conventional shale gas experimental procedures. This lays the foundation for conducting visualization shale thin section seepage experiments with different bedding types, pressures, and injection media, clarifying the impact of different bedding types on shale gas reservoir flow patterns and development characteristics.

[0061] Based on the same inventive concept, this embodiment of the invention also provides a microscopic visualization thin section, which is manufactured according to the above-described method for manufacturing microscopic visualization thin sections for analyzing the flow characteristics of shale bedding.

[0062] Based on the same inventive concept, this embodiment of the invention also provides a shale bedding flow characteristic analysis simulation system. This system may include: an optical microscope, a fluid injection device, and a microscopic visualization thin section manufactured using the aforementioned method for fabricating microscopic visualization thin sections for shale bedding flow characteristic analysis. The fluid injection device is connected to a quartz pipeline of the microscopic visualization thin section to inject fluid into it. The optical microscope is used to observe the bedding flow characteristics of the fluid in the microscopic visualization thin section to determine the shale gas reservoir flow pattern. The simulation system in this embodiment can simulate seepage experiments under different pressures and conditions to simulate the process of underground oil and gas migration and reservoir formation, laying the foundation for shale gas exploration and development.

[0063] The beneficial effects and detailed descriptions of the above-mentioned micro-visualization thin section and shale bedding flow characteristic analysis simulation system provided in the embodiments of the present invention can be found in the above-mentioned method for preparing micro-visualization thin sections for shale bedding flow characteristic analysis, and will not be repeated here.

[0064] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A method for preparing microscopically visualized thin sections for analyzing the flow characteristics of shale bedding, characterized in that, include: Shale thin sections obtained from shale sample slicing are ground to a thickness of 30-40 μm; The ground shale sheet is sandwiched between two pieces of plexiglass with a thickness of 0.2 to 0.3 mm and placed in an inlay machine for hot pressing, so that the plexiglass sheet and the shale sheet are pressed into one piece. A hole is drilled in the radial direction of the plexiglass sheet using a drill bit with a diameter of 0.7 to 0.9 mm, so that the hole after drilling is connected to the shale sheet. One end of a quartz microtube with an inner diameter of 0.5 mm is inserted into the hole and fixed, while the other end is connected to a quartz tube with an inner diameter of 1.6 mm to produce a microscopic visualization sheet for analyzing the flow characteristics of shale bedding.

2. The method according to claim 1, characterized in that, The grinding process of shale thin sections obtained from shale sample slicing includes: A randomly selected side of a shale section obtained from shale sample slicing is ground. The shale thin slice with the grinding treatment is attached to a glass slide. After standing, the other side of the shale thin slice is ground by hand with the glass slide. After grinding to a thickness of 30-40 μm, it is polished with a polishing machine. The polished shale slices and glass slides are immersed in an organic solvent to separate them. After removal, the shale slices are dried.

3. The method according to claim 2, characterized in that, The shale thin sections are subjected to grinding, including: Gradually use 400-mesh, 800-mesh, and 2000-mesh sandpaper for coarse grinding to achieve a surface roughness of 6.5–3.5 μm for the coarsely ground shale flakes; The coarsely ground shale flakes are finely ground using a grinding machine to achieve a surface roughness of 1.6–0.1 μm.

4. The method according to claim 2, characterized in that, The drying conditions for drying the shale flakes are as follows: place the shale flakes in an oven at 100-105°C and dry for 24-48 hours.

5. The method according to any one of claims 2 to 4, characterized in that, The adhesive used to bond the shale sheet and the glass slide is a resin-based adhesive. The adhesive used to fix the quartz microtube with an inner diameter of 0.5 mm in the hole is a resin-based adhesive, and / or the adhesive used to connect the quartz microtube with an inner diameter of 0.5 mm to the quartz tubing with an inner diameter of 1.6 mm is a resin-based adhesive. The resin adhesive is either acrylic resin adhesive or epoxy resin adhesive.

6. The method according to claim 5, characterized in that, When using resin-based adhesive to connect the quartz microtubes, the distance between the adhesive and the port of the quartz microtube should be no less than 2 mm.

7. The method according to claim 5, characterized in that, When using the resin adhesive to fix the quartz microtube, it should be placed at room temperature for at least 24 hours.

8. The method according to claim 1, characterized in that, The hot pressing temperature of the inlay machine is 120-130℃.

9. The method according to claim 1, characterized in that, Before hot pressing using the mounting machine, the process further includes: placing a certain amount of acrylic powder into the mounting machine for hot pressing to produce an acrylic sheet with a thickness of 0.2 to 0.3 mm.

10. A microscopically visualized thin film, characterized in that, The micro-visualization thin section is manufactured using the method for manufacturing micro-visualization thin sections for analyzing the flow characteristics of shale bedding according to any one of claims 1 to 9.

11. A shale bedding flow characteristic analysis and simulation system, characterized in that, include: A microscopic visualization thin section made from an optical microscope, a fluid injection device, and a method for making a microscopic visualization thin section for analyzing the flow characteristics of shale bedding according to any one of claims 1 to 9; The fluid injection device is connected to the quartz tubing of the micro-visualization sheet to inject fluid into the micro-visualization sheet. The optical microscope is used to observe the layered flow characteristics of fluids in the microscopic visualization section in order to determine the flow patterns of shale gas reservoirs.

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