A Gravity Flow Deposition Film for Core Particles, Its Preparation Method and Application

Abstract

This invention provides a core particle gravity flow deposition film, its preparation method, and its application. The preparation method includes the following steps: (1) grinding and screening core particles sequentially to obtain core nanoparticles; (2) mixing water and the core nanoparticles obtained in step (1) to obtain a suspension; (3) transferring the suspension obtained in step (2) to a solid matrix plate, allowing it to settle, and drying to obtain the core particle gravity flow deposition film. The core particle gravity flow deposition film provided by this invention can achieve accurate analysis of reservoir core permeation characteristics and has broad application scenarios in the field of reservoir wettability and permeation research.

Description

Technical Field

[0001] This invention belongs to the field of oil reservoir production engineering technology, specifically relating to a core particle gravity flow deposition film, its preparation method, and its application. Background Technology

[0002] The main methods for studying the permeation of oil reservoirs include volumetric methods, mass methods, nuclear magnetic resonance methods, and CT scanning methods. These are all experimental means currently used in the field of reservoir engineering to study the permeation characteristics of reservoirs.

[0003] The volumetric method uses Amott seepage bottles to measure the volume of produced crude oil to obtain the final seepage recovery rate. The apparatus consists of two parts: an upper graduated capillary tube and a lower transparent glass container. Produced crude oil floats to the capillary tube by buoyancy, and the seepage recovery rate can be calculated by measuring the volume of the crude oil. This method is simple to operate and can be used for batch seepage experiments, making it the most widely used seepage testing method currently. Its disadvantages include limitations imposed by the container volume and graduation range, affecting the experimental results, and the inability to measure the volume of crude oil adhering to the rock surface.

[0004] To address the limitation of volumetric methods in measuring the volume of crude oil adhering to the rock surface, Pu Yu et al. designed a percolation experimental method to calculate the volume of oil recovered through percolation by measuring changes in mass. The basic principle is that the wetting phase (water) and the non-wetting phase (oil) in the core undergo percolation displacement, and the density difference between oil and water allows for quantitative analysis of the degree of percolation recovery. During the experiment, changes in core weight are monitored in real-time using an electronic balance, offering convenience and speed. However, due to the large amount of crude oil adhering to the rock surface, a measurement error exceeding 100% in the percolation recovery rate may occur.

[0005] Nuclear magnetic resonance (NMR) utilizes the resonance properties of hydrogen atoms under a magnetic field to clarify the distribution patterns of fluids within rock pores. This method can obtain grayscale images of oil and water distribution without damaging the core morphology, and calculate changes in oil saturation to obtain the enhanced oil recovery rate. It is more accurate and provides more comprehensive information than the previous two methods, but it is cumbersome to operate and has higher testing costs.

[0006] CT scanning uses X-rays to irradiate the target rock core, and combines this with the principle of X-ray attenuation to visualize the core in three dimensions. This allows for quantitative analysis of the porosity values ​​and distribution of the core under different conditions. Compared to the aforementioned volumetric and gravimetric methods, CT scanning avoids the errors inherent in these methods because the measuring instruments do not directly contact the rock. However, CT scanning also has drawbacks such as high cost and long testing time.

[0007] Based on the above characteristics of application and testing, it is necessary to improve the existing reservoir permeation methods to make the permeation characteristics studied more obvious and stable, thus making the methods for studying the permeation characteristics of reservoir cores more reliable and broadening their application scope.

[0008] Furthermore, previous core-based permeation studies have yielded relatively few methods for rapidly detecting permeation in core samples. It is well known that core pretreatment is a complex and time-consuming process. Therefore, addressing this issue requires developing a portable method for studying core permeation characteristics and establishing an accurate, rapid, simple, and cost-effective detection method. Among these, core smoothing is key to resolving the aforementioned contradictions. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a core particle gravity flow deposition film, its preparation method, and its applications. This core particle gravity flow deposition film enables precise analysis of reservoir core permeability characteristics and has broad application prospects in the field of reservoir wettability and permeability research.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a gravity flow deposition film of core particles, the method comprising the following steps:

[0012] (1) The core particles were successively ground and screened to obtain core nanoparticles;

[0013] (2) Mix water and the core nanoparticles obtained in step (1) to obtain a suspension;

[0014] (3) The suspension obtained in step (2) is transferred to a solid matrix plate, allowed to stand and settle, and dried to obtain the gravity flow deposition film of the core particles.

[0015] The method for preparing gravity flow deposition films of core particles provided by this invention is simple and convenient, and can achieve accurate analysis of the permeation characteristics of reservoir cores.

[0016] The core particles in step (1) of this invention originated from a certain area outside Daqing as the research target block, and the core sampling depth was 1800.9-1896.1m.

[0017] As a preferred technical solution of the present invention, step (1) further includes a crushing process before grinding.

[0018] Preferably, the mass ratio of core particles to grinding balls in the grinding process is 3:(4-6), for example, it can be 3:4, 3:4.03, 3:5 or 3:6, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the grinding speed is 300 to 500 r / min, for example, it can be 300 r / min, 350 r / min, 400 r / min, 450 r / min or 500 r / min, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0020] Preferably, the grinding time is 240 to 280 minutes, for example, 240 minutes, 250 minutes, 260 minutes, 270 minutes or 280 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] It is worth noting that the crushing described in this invention involves using a grinding pestle to pulverize the rock core to 1 cm. 3 The particles are approximately [size missing]. The grinding process involves using a vertical planetary ball mill (YXQM-0.4L) to grind the crushed core particles, with a grinding cycle of 30 minutes followed by a 5-minute downtime. The number of grinding balls is 1:2:10, with small balls being 5mm in diameter and weighing 0.25g each, medium balls being 10mm in diameter and weighing 0.33g each, and large balls being 15mm in diameter and weighing 0.86g each. The screening process involves using a laser particle size analyzer (Mastersizer3000) for particle size confirmation and sieving.

[0022] Preferably, the particle size of the core nanoparticles in step (1) is 500 to 3000 nm, for example, it can be 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm or 3000 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] As a preferred technical solution of the present invention, the ratio of water to core nanoparticles in step (2) is 30mL:(0.1~0.5)g, for example, it can be 30mL:0.1g, 30mL:0.2g, 30mL:0.3g, 30mL:0.4g or 30mL:0.5g, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the mixing in step (2) includes ultrasonic mixing.

[0025] Preferably, the ultrasonic mixing time is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the power of the ultrasonic mixing is 80 to 120W, for example, it can be 80W, 90W, 100W, 110W or 120W, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0027] Preferably, the frequency of the ultrasonic mixing is 30 to 50 kHz, for example, it can be 30 kHz, 35 kHz, 40 kHz, 45 kHz or 50 kHz, but is not limited to the listed values. Other values ​​not listed in the range are also applicable.

[0028] The purpose of ultrasonic mixing described in this invention is to prevent core particles from agglomerating in water and to ensure that the core particles are fully dispersed in water.

[0029] It is worth noting that, in order to make the gravity flow deposition film of the core particles closer to the mineralization conditions of the actual strata, the preparation method of the present invention also includes adding metal ion solution or pure water to the suspension in step (2).

[0030] As a preferred technical solution of the present invention, the size of the solid substrate plate in step (3) is (2~3)cm×(3~5)cm, for example, it can be 2.5cm×4cm, 2cm×5cm, 2cm×3cm, 2.5cm×4.5cm or 3cm×3.5cm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the solid substrate plate in step (3) comprises any one of quartz, hydrophilic glass, or quartz glass.

[0032] The solid substrate board described in this invention is a transparent, impermeable solid substrate.

[0033] As a preferred technical solution of the present invention, the transfer in step (3) includes: extracting the suspension obtained in step (2) and injecting it onto the solid matrix plate.

[0034] Preferably, the amount of suspension extracted is 1.0 to 3.0 mL, for example, 1.0 mL, 1.5 mL, 2 mL, 2.5 mL or 3 mL, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] As a preferred technical solution of the present invention, the instruments used in the transfer in step (3) include a dual-channel pump or a syringe.

[0036] It is worth noting that the dual-channel pump described in this invention is the FUSION 100 microfluidic infusion pump dual-channel syringe pump; the syringe is a standard 10mL laboratory syringe.

[0037] Preferably, the injection rate is 0.8 to 1.5 mL / min, for example, it can be 0.8 mL / min, 0.8 mL / min, 1.0 mL / min, 1.1 mL / min, 1.2 mL / min, 1.3 mL / min, 1.4 mL / min or 1.5 mL / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] The injection rate described in this invention is 0.8 to 1.5 mL / min. If the injection rate is too high, the mixed suspension will form a jet with an initial velocity, which will impact the deposited liquid film and make it impossible to achieve stable and uniform particle deposition. If the injection rate is too low, the local deposited film will evaporate and dry first, and cracks will appear in the horizontal direction of the film.

[0039] As a preferred embodiment of the present invention, the temperature for settling is 20-30°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the solid matrix plate is placed horizontally during the static sedimentation process.

[0041] Preferably, the settling time is 22 to 28 hours, for example, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours or 28 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] It is worth noting that during the static sedimentation process described in this invention, it is necessary to ensure that the ambient air is undisturbed and the experimental platform is vibration-free to ensure stable particle deposition without interference.

[0043] As a preferred embodiment of the present invention, the preparation method includes pretreatment of the solid substrate plate in step (3).

[0044] Preferably, the pretreatment includes sequentially cleaning and drying the solid substrate plate.

[0045] The purpose of the pretreatment described in this invention is to clean the dust off the solid substrate and perform drying treatment, which helps the liquid to disperse and spread in a uniform and stable form when injecting the mixed suspension, and avoids dust and particulate matter from attracting the liquid film, forming local circulation and uneven liquid film.

[0046] As a preferred embodiment of the present invention, the method for preparing a core particle gravity flow deposition film provided in the first aspect of the present invention includes the following steps:

[0047] (1) The core particles were crushed, ground and screened in sequence to obtain core nanoparticles with a particle size of 500-3000 nm.

[0048] The grinding speed is 300-500 r / min, and the grinding time is 240-280 min;

[0049] (2) A suspension was obtained by ultrasonically mixing water and core nanoparticles obtained in step (1) at a ratio of 30 mL: (0.1-0.5) g.

[0050] The ultrasonic mixing time is 20–40 min, the power is 80–120 W, and the frequency is 30–50 kHz.

[0051] (3) The suspension obtained in step (2) is transferred to a solid matrix plate with a size of (2-3)cm × (3-5)cm, and after standing and settling and drying, the core particle gravity flow deposition film is obtained.

[0052] The transfer includes: extracting 1.0 to 3.0 mL of the suspension obtained in step (2) and injecting it into the solid matrix plate at a rate of 0.8 to 1.5 mL / min;

[0053] The settling temperature is 20–30°C; the settling time is 22–28 h; and the solid matrix plate is placed horizontally during the settling process.

[0054] Secondly, the present invention provides a core particle gravity flow deposition film, which is obtained by the preparation method provided in the first aspect.

[0055] The thickness of the gravity flow deposition film of the core particles is 1.5 × 10⁻⁶. 5 ~5.5×10 5 nm, for example, could be 1.5 × 10 5 nm, 2.5×10 5 nm, 3.5×10 5 nm, 4.5×10 5 nm or 5.5×10 5 nm, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0056] The thickness of the gravity flow deposition film of the core particles described in this invention is 1.5 × 10⁻⁶. 5 ~5.5×10 5nm, if the deposition film is too thick, it will cause unevenness on the surface of the deposition film and large differences in surface pores, and the test droplets will penetrate into the interior of the deposition film, making it difficult to measure; if the deposition film is too thin, there will be few particles in some areas, and the liquid will be easily attracted by the underlying hydrophilic glass matrix.

[0057] Thirdly, the present invention provides an application of a core particle gravity flow deposition membrane as provided in the second aspect, wherein the core particle gravity flow deposition membrane is used to detect and analyze the seepage wetting characteristics of an oil reservoir.

[0058] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The core particle gravity flow deposition film provided by the present invention can realize the accurate analysis of reservoir core permeation characteristics and has a wide range of applications in the field of reservoir wettability and permeation research.

[0061] (2) The core particle gravity flow deposition film provided by the present invention is a two-dimensional thin film. Direct detection of permeation characteristics on the two-dimensional thin film core plane can also improve the accuracy of permeation characteristic detection, improve the stability and reliability of measurement, and expand the application range of core films.

[0062] (3) The core particle gravity flow deposition film provided by the present invention can be used to directly detect the permeation characteristics of reservoir cores in the laboratory observation system, eliminating the need for pretreatment processes such as sample preparation and sampling, and enabling accurate detection of the sample to be tested. Attached Figure Description

[0063] Figure 1 This is an electron microscope image of the gravity flow deposition film of core particles provided in Embodiment 3 of the present invention;

[0064] Figure 2 This is a graph showing the height variation of the gravity flow deposition film of core particles in the X (horizontal) direction, as provided in Examples 3-7 of this invention.

[0065] Figure 3 This is a schematic diagram of the wetting angle change process captured by the gravity flow deposition film of core particles in the X (horizontal) direction, provided in Embodiment 3 of the present invention. Detailed Implementation

[0066] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0067] The sources of some components in the following examples and comparative examples are as follows:

[0068] Example 1

[0069] This embodiment provides a gravity flow deposition film of core particles, and the preparation method of the gravity flow deposition film of core particles includes the following steps:

[0070] (1) The core particles were crushed, ground and screened in sequence to obtain core nanoparticles with a particle size of 500 nm.

[0071] The grinding speed is 400 r / min and the grinding time is 250 min;

[0072] (2) A suspension was obtained by ultrasonically mixing water and core nanoparticles obtained in step (1) at a ratio of 30 mL: 0.3 g.

[0073] The ultrasonic mixing time is 30 minutes, the power is 100W, and the frequency is 40kHz.

[0074] (3) Transfer the suspension obtained in step (2) onto a quartz glass plate with dimensions of 2.5cm × 4cm, allow it to settle and precipitate, and then dry to obtain a thickness of 1.5 × 10. 5 nm core particles gravity flow deposition film;

[0075] The transfer includes: extracting 2.5 mL of the suspension obtained in step (2) and injecting it into the solid matrix plate at a rate of 1 mL / min;

[0076] The settling temperature is 30℃; the settling time is 24h; and the solid matrix plate is placed horizontally during the settling process.

[0077] Example 2

[0078] This embodiment provides a gravity flow deposition film of core particles, and the preparation method of the gravity flow deposition film of core particles includes the following steps:

[0079] (1) The core particles were crushed, ground and screened in sequence to obtain core nanoparticles with a particle size of 3000 nm.

[0080] The grinding speed is 500 r / min and the grinding time is 280 min;

[0081] (2) A suspension was obtained by ultrasonically mixing water and core nanoparticles obtained in step (1) at a ratio of 30 mL: 0.5 g.

[0082] The ultrasonic mixing time is 40 min, the power is 120 W, and the frequency is 50 kHz.

[0083] (3) Transfer the suspension obtained in step (2) onto a quartz glass plate with dimensions of 2.5cm × 4cm, allow it to settle and precipitate, and then dry to obtain a thickness of 5.5 × 10. 5 nm core particles gravity flow deposition film;

[0084] The transfer includes: extracting 2 mL of the suspension obtained in step (2) and injecting it into the solid matrix plate at a rate of 0.8 mL / min;

[0085] The settling temperature was 25°C and the settling time was 28 hours. The solid matrix plate was placed horizontally during the settling process.

[0086] Example 3

[0087] This embodiment provides a gravity flow deposition film of core particles, and the preparation method of the gravity flow deposition film of core particles includes the following steps:

[0088] (1) The core particles were crushed, ground and screened in sequence to obtain core nanoparticles with a particle size of 1000 nm.

[0089] The grinding speed is 300 r / min and the grinding time is 240 min;

[0090] (2) The water and the core nanoparticles obtained in step (1) were ultrasonically mixed at a ratio of 30 mL: 0.1 g to obtain a suspension;

[0091] The ultrasonic mixing time is 30 minutes, the power is 80W, and the frequency is 30kHz.

[0092] (3) Transfer the suspension obtained in step (2) onto a quartz plate with dimensions of 2.5cm × 4cm, allow it to settle and precipitate, and then dry to obtain a thickness of 3.5 × 10. 5 nm core particles gravity flow deposition film;

[0093] The transfer includes: extracting 1.0 to 3.0 mL of the suspension obtained in step (2) and injecting it into the solid matrix plate at a rate of 1.5 mL / min;

[0094] The settling temperature was 20°C and the settling time was 22 hours; the solid matrix plate was placed horizontally during the settling process.

[0095] The electron microscope image of the gravity flow deposition film of the core particles provided in this embodiment is as follows: Figure 1 As shown.

[0096] Example 4

[0097] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0098] In this embodiment, the core nanoparticles described in step (1) are modified to 750 nm, resulting in a thickness of 2.5 × 10⁻⁶. 5 A core particle gravity flow deposition film of nm.

[0099] Example 5

[0100] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0101] In this embodiment, the core nanoparticles described in step (1) are modified to 500 nm, resulting in a thickness of 1.5 × 10⁻⁶. 5 A core particle gravity flow deposition film of nm.

[0102] Example 6

[0103] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0104] In this embodiment, the core nanoparticles described in step (1) are modified to 1500 nm, resulting in a thickness of 4 × 10⁻⁶. 5 A core particle gravity flow deposition film of nm.

[0105] Example 7

[0106] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0107] In this embodiment, the core nanoparticles mentioned in step (1) are modified to 2000 nm, resulting in a thickness of 5.5 × 10⁻⁶. 5 A core particle gravity flow deposition film of nm.

[0108] The height variation curves of the gravity flow deposition film of core particles provided in Examples 3-7 above are shown in the X (horizontal) direction. Figure 2 As shown.

[0109] Example 8

[0110] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0111] In this embodiment, the injection rate described in step (3) is modified to 0.5 mL / min.

[0112] Example 9

[0113] This embodiment provides a core particle gravity flow deposition film, and the preparation method of the core particle gravity flow deposition film differs from that of Embodiment 3 only in that:

[0114] In this embodiment, the injection rate described in step (3) is modified to 2 mL / min.

[0115] Comparative Example 1

[0116] This comparative example provides a gravity flow deposition film of core particles. The preparation method of the gravity flow deposition film of the core particles differs from that of Example 3 only in that:

[0117] This comparative example omits the screening process described in step (1), meaning that the particle size of the core nanoparticles obtained in step (1) is not unique, and its particle size ranges from 500 to 2000 nm.

[0118] Application examples

[0119] The adsorption and wetting characteristics of the reservoir were analyzed using the gravity flow deposition film of core particles provided in the above embodiments and comparative examples. The specific process includes the following steps:

[0120] The contact angle of the core sedimentary film was measured using a contact angle meter (KRUSS DSA100) and the droplet method. Five measurements were performed on each film sample, and the wetting angle distribution was recorded.

[0121] Simultaneously, utilizing an orthogonal spatial high-speed camera observation experimental platform, contact angles can be observed and captured through horizontal observation; in the vertical direction, the proportion and size of pixels in the imaging area are calibrated by using the camera lens magnification, and the wetting and spreading radii are calculated, thereby achieving the acquisition of wetting and absorption rates. Contact angles are precisely calibrated and recorded using a high-speed camera in the horizontal direction.

[0122] The wetting angle values ​​of the core particle gravity flow deposition films provided in the above embodiments and comparative examples, measured in the X (horizontal) direction, are shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] The wetting angle variation process captured in the X (horizontal) direction by the gravity flow deposition film of core particles provided in Example 3 of this invention is as follows: Figure 3 As shown.

[0127] according to Figure 3The entire contact process can be summarized as follows: a- The droplet initially contacts the deposition film; b- The droplet gradually penetrates the film; c- The bottom of the droplet has infiltrated the film; d- The droplet undergoes dialysis within the film. Finally, it reaches a stable state with a stable contact angle of 38.4°. Observing the droplet's behavior throughout the process reveals that the core sample exhibits strong overall hydrophilicity, consistent with the characteristics of dry sandstone layers in the pre-grinding sample.

[0128] analyze Figure 2 It is known that the core particle gravity flow deposition film provided by this invention has different deposition thicknesses. As the particle size increases from 500 nm to 2000 nm, the thickness of the deposition film increases from approximately 1.5 × 10⁻⁶. 5 Increased to 5.5×10 5 The nm value indicates that as the grain size increases, the film particles form different skeletal structures, with larger core particles exhibiting greater accumulation height after deposition. Simultaneously, surface roughness reveals minimal vertical undulations in the same type of film. Under the reference deposition plane, the average undulation height is approximately 300 nm, with a maximum undulation height of approximately 500 nm, indicating very low surface roughness and high smoothness of the deposited film.

[0129] In summary, the core particle gravity flow deposition film provided by this invention can achieve accurate analysis of reservoir core permeation characteristics and has broad application scenarios in the field of reservoir wettability and permeation research.

[0130] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0131] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method of preparing a core grain gravity flow deposit film, characterized by, The preparation method includes the following steps: (1) The core particles were ground and screened sequentially to obtain core nanoparticles; The particle size of the core nanoparticles in step (1) is 500~3000 nm; (2) Mix water and the core nanoparticles obtained in step (1) to obtain a suspension; (3) The suspension obtained in step (2) is transferred to a solid matrix plate, allowed to stand and settle, and dried to obtain the gravity flow deposition film of the core particles; The transfer in step (3) includes: extracting the suspension obtained in step (2) and injecting it onto the solid matrix plate; The injection rate is 0.8~1.5 mL / min; The temperature for static sedimentation is 20~30℃; The solid matrix plate is placed horizontally during the static sedimentation process; The settling time is 22-28 hours; The thickness of the gravity flow deposition film of the core particles prepared by the method described above is 1.5 × 10⁻⁶. 5 ~5.5×10 5 nm.

2. The production method according to claim 1, characterized by, Step (1) includes a crushing process before grinding.

3. The preparation method according to claim 1, characterized in that, The weight ratio of core particles to grinding balls in the grinding process is 3:(4~6).

4. The method of claim 1, wherein, The grinding speed is 300~500 r / min.

5. The preparation method according to claim 1, characterized in that, The grinding time is 240~280 min.

6. The method of claim 1, wherein, The ratio of water to core nanoparticles in step (2) is 30 mL: (0.1~0.5) g.

7. The preparation method according to claim 1, characterized in that, The mixing in step (2) includes ultrasonic mixing.

8. The preparation method according to claim 7, characterized in that, The ultrasonic mixing time is 20-40 minutes.

9. The preparation method according to claim 7, characterized in that, The power of the ultrasonic mixing is 80~120W.

10. The preparation method according to claim 7, characterized in that, The frequency of the ultrasonic mixing is 30~50kHz.

11. The preparation method according to claim 1, characterized in that, The solid substrate plate in step (3) has a size of (2~3)cm × (3~5)cm.

12. The preparation method according to claim 1, characterized in that, The solid substrate plate in step (3) includes any one of quartz, hydrophilic glass, or quartz glass.

13. The preparation method according to claim 1, characterized in that, The amount of suspension extracted is 1.0~3.0 mL.

14. The preparation method according to claim 5, characterized in that, The instruments used in the transfer in step (3) include a dual-channel pump or a syringe.

15. The preparation method according to claim 1, characterized in that, The preparation method includes pretreatment of the solid substrate plate in step (3).

16. The preparation method according to claim 15, characterized in that, The pretreatment includes sequentially cleaning and drying the solid substrate plate.

17. A gravity flow deposition film for core particles, characterized in that, The core particle gravity flow deposition film is obtained by the preparation method described in any one of claims 1-16.

18. An application of the gravity flow deposition film of core particles as described in claim 17, characterized in that, The gravity flow deposition film of the core particles is used to detect and analyze the seepage wetting characteristics of the reservoir.

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