3D printing method of multi-layer functional coating rock core suitable for well cementation extreme environment

Abstract

The invention discloses a 3D printing method of a multi-layer functional coating core suitable for a well cementation extreme environment, which comprises the following steps: (1) selecting a natural core sample, performing layered scanning by using a three-dimensional white light scanner, and processing scanning data through reverse analysis software to generate a three-dimensional model file; (2) setting the shape and size of a target rock core, reserving a groove for placing a micro sensor in the target rock core, dividing the rock core into an inner layer, a middle layer and an outer layer in equal proportion, and completing a 3D model of the target rock core when the groove is located in the inner layer; (3) printing materials of the inner layer, the middle layer and the outer layer are selected; and (4) transmitting the rock core 3D data to a 3D printer data processor, adopting a layer-by-layer printing mode, sequentially filling printing materials of each layer, setting proper printing parameters according to different printing materials, and printing to form a complete rock core. Through material optimization and microporous structure design, the rock core has excellent stability and durability in underground high-temperature, high-pressure and corrosive environments.

Description

Technical Field

[0001] The present invention belongs to the field of artificial core preparation, and specifically relates to a 3D printing method for a multi-layer functional coating core in an extreme cementing environment, which can have excellent stability and durability in high temperature, high pressure and corrosive environments in oil and gas wells. Background Art

[0002] With the deepening of oil and gas well resource development, the temperature, pressure and acid-base conditions faced by oil and gas wells are becoming increasingly severe. In order to improve the quality of cementing and ensure construction safety, formation core sampling must be carried out to carry out cementing interface performance evaluation and related fluid experiments. However, natural core sampling is costly and difficult, so artificial cores are usually used instead of natural cores for experiments.

[0003] Artificial cores play a key role in cementing operations in oil and gas fields, but the deficiencies of existing technologies in material properties and processing technology have resulted in limited performance in extreme environments, making it difficult to meet the requirements of harsh conditions such as high temperature, high pressure, and strong acid and alkali. "Method for preparing artificial cores based on 3D printing technology and finished artificial cores" (CN109253910A) uses 3D printing technology to prepare finished cores, and then conducts core flow experimental tests; "A core preparation device and method based on photocuring 3D printing technology" (CN115464883A) uses photocuring 3D printing technology to prepare multifunctional artificial cores; "Method for simulating high-permeability cores of different levels of reservoirs by 3D printing" (CN114428001A) first uses CT scanning technology to obtain the internal structure of the formation core, and then prints the core layer by layer through 3D printing technology. However, these technical solutions mainly focus on the structural reconstruction of the core, and fail to fully solve the problems of material tolerance and process details.

[0004] Given that existing 3D printed cores are not able to withstand extreme conditions, it is particularly necessary to develop artificial cores that can adapt to extreme working environments. This can not only further optimize the drilling fluid system and improve the overall quality of cementing operations, but is also of great significance to the effective exploitation and protection of oil and gas resources. Summary of the invention

[0005] The purpose of the present invention is to provide a 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments. The method has a reliable principle and is easy to operate. Through material optimization and microporous structure design, it can remain stable in high temperature, high pressure and corrosive environments. It is used for cementing interface bonding strength and flushing experiments to further evaluate the bonding performance of the cement slurry and formation interface during the cementing process. At the same time, the core can monitor external environmental parameters in real time and has broad market application prospects.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions.

[0007] The present invention uses high temperature resistant, corrosion resistant, high strength materials, combined with special micropore design and anti-corrosion and wear resistant coatings, and uses 3D printing technology to manufacture cores that meet actual needs. The cores have excellent stability and durability in high temperature, high pressure and corrosive environments, and the embedded sensor system can monitor external environmental parameters in real time, thereby further improving the accuracy of experimental data.

[0008] The 3D printing method of a multi-layer functional coating core suitable for extreme cementing environments comprises the following steps in sequence:

[0009] (1) Select natural core samples, determine the printing area of ​​their structural surfaces, use a 3D white light scanner to perform layered scanning, obtain data on the natural structural surfaces, process the scanned data using reverse analysis software, optimize the surface mesh density and edge details, and generate a high-precision 3D model file;

[0010] (2) Open the 3D model file generated in step (1) in the CAD software, set the shape and size of the target core, retain the external geometric shape, remove unnecessary internal structural data, and reserve a groove inside the core for placing the micro sensor. Divide the target core into three areas of equal proportion: inner layer, middle layer, and outer layer, and the groove is located in the inner layer, thereby completing the 3D model of the target core;

[0011] (3) Select the printing materials for the inner layer, middle layer and outer layer, the inner layer is the core layer, the printing materials include but are not limited to copper, copper alloy, aluminum nitride, graphite, polyvinylidene fluoride and other highly conductive materials, the middle layer is functional, the printing materials include but are not limited to carbon fiber reinforced nylon, glass-filled nylon, polyetheretherketone and other high-strength, high-temperature resistant materials, the outer layer is the protective layer, the printing materials include but are not limited to silicon nitride, silicon carbide, polytetrafluoroethylene, nickel-based alloy and other highly corrosion-resistant and wear-resistant materials;

[0012] (4) The 3D data of the target core is transmitted to the data processor of the 3D printer, and each layer of printing material is filled in turn in a layer-by-layer printing manner. Appropriate printing parameters are set according to different printing materials. The inner layer area of ​​the target core is printed first, and the printing is paused when the reserved groove position is reached to embed the micro sensor, and then the middle layer area is printed. Finally, the outer layer area is printed to form a complete core.

[0013] Furthermore, in step (2), the shape of the target core can be a cuboid, a cube or a cylinder. For a cuboid or a cube core, the length, width and height ranges are 15-200 mm, 15-200 mm and 15-300 mm respectively; for a cylindrical core, the diameter is 15-200 mm and the height is 15-300 mm. The selection of these sizes is based on the requirements under different experimental conditions and can flexibly adapt to various experimental environments.

[0014] Furthermore, in step (2), the size of the groove is 7 mm×7 mm×4 mm, which is suitable for embedding a standard micro sensor, ensuring that the groove can safely accommodate the sensor and maintain its functional integrity.

[0015] Furthermore, in step (4), in order to ensure the firm bonding and structural stability between the inner layer and the middle layer, and between the middle layer and the outer layer of the target core, the surface of the material needs to be treated accordingly.

[0016] Furthermore, the corresponding treatment of the material surface refers to selecting corresponding adhesives according to the bonding requirements of different materials. For the bonding area between metal materials and polymers, epoxy resin or polyurethane adhesives are selected. These two adhesives have excellent bonding strength and chemical stability and are suitable for maintaining long-term bonding in high temperature and high pressure environments; for the bonding area between polymers and ceramic materials or graphite, high-temperature epoxy resin or silicone adhesives are selected to ensure the stability and durability of bonding in high temperature environments.

[0017] Furthermore, in the bonding area between the metal material and the polymer, the roughness of the metal material surface is increased by mechanical grinding and sandblasting processes, thereby enhancing the adhesion of the adhesive.

[0018] Furthermore, in step (4), the microsensor is a NOVOSENSE NSPAS3 microsensor, which can detect changes in temperature and pressure of the external environment. Its compact design is suitable for embedding in 3D printed cores while maintaining stability and accuracy under high temperature and high pressure.

[0019] Furthermore, in the step (4), layer-by-layer printing means first adding the printing material of the inner layer of the core into the material guide port of the 3D printer, setting the printing parameters, and after the inner layer printing is completed, removing the inner layer printing material and replacing it with the middle layer printing material, resetting the printing parameters according to the characteristics of the middle layer material, and starting the printing of the middle layer area. After the middle layer printing is completed, the material is replaced according to the same process, the printing parameters are adjusted, and finally the printing of the outer layer area is completed.

[0020] Furthermore, in step (4), the printing parameters are set as follows:

[0021] Laser power: ranges from 10W to 200W, depending on the material's absorption rate and melting point, ensuring uniform melting and reducing material loss.

[0022] Scanning speed: The speed at which the laser beam moves across the powder bed is 1000mm / s-7000mm / s. Lower speeds are suitable for fine printing of complex structures, while higher speeds are used to quickly manufacture larger parts.

[0023] Scanning spacing: The range is 0.1mm-0.5mm. The adjustment of the spacing determines the fineness and surface smoothness of the printed layer.

[0024] Layer thickness: The powder layer thickness is 0.05mm-0.2mm. Thinner layers provide higher printing resolution and are suitable for fine structures, while thicker layers are suitable for parts that require high strength and do not require high resolution.

[0025] Bed temperature: The print bed temperature is 80℃-200℃, which is close to the glass transition temperature of the material, reducing warping and internal stress.

[0026] Ambient temperature: The temperature of the printing environment is set to 60℃-200℃. Maintaining a stable temperature can reduce the accumulation of thermal stress and avoid deformation of parts.

[0027] Furthermore, in the step (4), after a complete core is formed, its outer surface needs to be treated according to the specific application requirements of the core. When used in a strong acid or strong alkali environment, a layer of epoxy resin coating is sprayed on the outer surface of the core to improve its corrosion resistance; when used in a high friction or high flow rate liquid environment, a layer of polytetrafluoroethylene coating is sprayed on the outer surface of the core to extend the service life of the core and reduce wear.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The artificial core prepared by the present invention has excellent mechanical properties and chemical stability, which enables it to be used in various experimental operations in complex and changeable extreme working environments, ensuring that the core can still maintain structural integrity and performance consistency under harsh conditions such as high temperature, high pressure, strong acid and strong alkali;

[0030] (2) The artificial core prepared by the present invention has a highly liberalized internal structure design, which can truly simulate the porosity and internal network structure of the actual underground reservoir rock, making the experimental data closer to the actual working conditions and providing a reliable experimental basis for subsequent reservoir analysis;

[0031] (3) The sensor system equipped with the artificial core can not only monitor environmental changes in real time, but also provide accurate data feedback according to the fluctuations of the external environment, which greatly improves the real-time and accuracy of the experimental process;

[0032] (4) Through surface treatment of the material interface, adhesive selection, heat treatment and interface design, the present invention effectively solves the bonding problem between materials of different levels, ensures the structural stability and functional integrity of the core under extreme environments, and thus greatly improves the long-term performance of the core under high temperature and high pressure conditions;

[0033] (5) No soluble support material is required in the preparation of artificial cores, which reduces the number of subsequent processing steps, shortens the overall processing time by about 30%, reduces the complexity of manual operations, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Flow chart of the method for 3D printing a multi-layer functional coating core.

[0035] Figure 2 Schematic diagram of the printed core structure.

[0036] Figure 3 This is a printed core cross section.

[0037] Figure 4 This is an enlarged view of the bonding area between the outer layer and the middle layer.

[0038] Figure 5 This is an enlarged view of the bonding area between the middle layer and the inner layer.

[0039] In the figure: 1-inner layer area of ​​the core; 2-middle layer area of ​​the core; 3-outer layer area of ​​the core; 4-micro wireless sensor; 5-bonding point between inner and middle layers; 6-bonding point between middle and outer layers. DETAILED DESCRIPTION

[0040] In order to help those skilled in the art better understand the present invention, the embodiments of the present invention are further described in conjunction with the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described, and various changes and adjustments made by ordinary technicians in the field without departing from the spirit and scope of the present invention should still be within the scope of protection of the present invention.

[0041] See also Figure 1 , Figure 2 , Figure 3 , the core prepared by the method of the present invention comprises:

[0042] Core inner region 1: It has high conductivity and sensing function, and is mainly used for real-time data acquisition and internal temperature management to ensure accurate feedback of temperature changes in extreme environments;

[0043] Middle core area 2: It has high strength and high temperature resistance, and maintains good structural integrity, providing overall structural support. It also has excellent heat resistance and can cope with physical stress in high temperature environments;

[0044] Core outer area 3: has excellent corrosion resistance, wear resistance and protection function, can effectively protect the internal structure from external physical impact and chemical corrosion damage, and extend the service life of the core;

[0045] Micro wireless sensor 4: used to sense pressure and temperature changes in the external environment, and transmit data to external devices through a wireless transmission system to ensure real-time monitoring of environmental parameters;

[0046] Inner and middle layer bonding 5: Through reasonable bonding treatment, ensure the firm bonding between the inner and middle layer materials to ensure the stability and reliability of the overall structure;

[0047] Middle and outer layer bonding point 6: Advanced bonding technology is used to enhance the bonding strength between the middle and outer layer materials to improve the durability of the material in extreme environments and the integrity of the overall structure.

[0048] 1. Preparation of multi-layer functional coating core suitable for extreme cementing environment

[0049] Example 1

[0050] (1) Core model construction: First, slice the natural rock sample and scan it layer by layer using a 3D white light scanner to obtain detailed data of the natural structural surface. Then, the scan data is processed by reverse analysis software to generate an accurate 3D model file. Open the model file in the CAD software, set the core shape to a cylindrical shape with a diameter of 60 mm and a height of 100 mm, and perform a layered design of the inner, middle, and outer layers. At the same time, a 7 mm × 7 mm × 4 mm groove is reserved for the subsequent embedding of the micro wireless sensor. Finally, save the model file in STL format for subsequent printing.

[0051] (2) Inner layer printing (copper alloy): Add copper alloy powder to the feed port of the SLS 3D printer and start setting the printing parameters. The printing parameters are set as follows:

[0052] Laser power: 100-120W

[0053] Scanning speed: 1500-2000mm / s

[0054] Layer thickness: 50-100 μm

[0055] Scanning distance: 0.1-0.2mm

[0056] Substrate temperature: 150-200℃

[0057] Laser focus: Aim at the material surface or slightly off the surface

[0058] During the printing process of the inner layer area, when printing reaches the reserved sensor groove, pause printing, manually place the micro wireless sensor, and continue printing until the inner layer printing is completed and cool for 30 minutes.

[0059] (3) Middle layer printing (carbon fiber reinforced polyetheretherketone, PEEK): The inner core surface is treated with epoxy resin spraying to improve the material adhesion. Then it is replaced with carbon fiber reinforced polyetheretherketone (PEEK) powder and the middle layer printing is started. The parameters are set as follows:

[0060] Laser power: 60-80W

[0061] Scanning speed: 2000-2500mm / s

[0062] Layer thickness: 50-100 μm

[0063] Scanning distance: 0.1-0.2mm

[0064] Substrate temperature: 200-250℃

[0065] Laser focus: Align to the material surface

[0066] After the middle layer is printed, it is cooled for 20 minutes and epoxy resin adhesive is sprayed on its surface to increase the bonding strength with the outer layer.

[0067] (4) Outer layer printing (nickel-based alloy Inconel 718): Replace the nickel-based alloy (Inconel 718) powder and set the outer layer printing parameters as follows:

[0068] Laser power: 80-100W

[0069] Scanning speed: 2500-3000mm / s

[0070] Layer thickness: 50-100 μm

[0071] Scanning distance: 0.1-0.15mm

[0072] Substrate temperature: 100-150℃

[0073] Laser focus: Align to the material surface

[0074] After the outer layer is printed, it is cooled for 1 hour. A soft brush is used to remove the unsintered powder on the surface of the core, and then a layer of polytetrafluoroethylene coating is sprayed on the outer layer to enhance the wear resistance and service life of the core, and finally the required core sample is obtained.

[0075] Example 1 is a combination of high thermal conductivity, high strength and corrosion resistance. The inner layer of the core uses copper alloy, which has excellent electrical and thermal conductivity and is suitable for high heat flow environments; the middle layer material is PEEK (polyetheretherketone), whose high strength and high temperature tolerance can ensure the stability of the structure; the outer layer is a nickel-based alloy (Inconel 718), which provides excellent corrosion resistance and high temperature resistance.

[0076] Example 2

[0077] (1) Core model construction: After slicing the natural rock sample, use a 3D white light scanner to scan it layer by layer to obtain detailed data of the natural structural surface. Then, the scan data is processed by reverse analysis software to generate an accurate 3D model data file. Use CAD software to open the model file, set the core shape to a 100mm×100mm×150mm cube, and partition the inner, middle and outer layers. Reserve a 7mm×7mm×4mm groove inside the core for embedding micro wireless sensors. Finally, save the data in STL file format for subsequent printing operations.

[0078] (2) Inner layer printing (aluminum nitride): First, pour aluminum nitride powder into the material guide port of the 3D printer and set the printing parameters. The specific parameters are as follows:

[0079] Laser power: 100-120W

[0080] Scanning speed: 1500-2000mm / s

[0081] Layer thickness: 50-100 μm

[0082] Scanning distance: 0.1-0.15mm

[0083] Substrate temperature: 150-200℃

[0084] Laser focus: Aim at the material surface or slightly off the surface

[0085] When printing reaches the reserved sensor groove, pause printing and manually place the micro wireless sensor. Continue printing the inner layer area until the inner layer printing is completed and cool for 20 minutes.

[0086] (3) Middle layer printing (carbon fiber reinforced nylon, CF-Nylon): Spray silicone adhesive on the inner layer surface to enhance the bonding between the middle layer and the inner layer. Then replace it with carbon fiber reinforced nylon (CF-Nylon) powder, and set the middle layer printing parameters as follows:

[0087] Laser power: 50-70W

[0088] Scanning speed: 2500-3000mm / s

[0089] Layer thickness: 50-100 μm

[0090] Scanning distance: 0.1-0.2mm

[0091] Substrate temperature: 80-120°C

[0092] Laser focus: Align to the material surface

[0093] After the middle layer is printed, it is cooled for 10 minutes and a polyurethane adhesive is sprayed on the surface of the middle layer to improve the bonding with the outer layer.

[0094] (4) Outer layer printing (stainless steel 316L): Replace with stainless steel (316L) powder and start printing the outer layer area. The printing parameters are set as follows:

[0095] Laser power: 80-100W

[0096] Scanning speed: 2000-2500mm / s

[0097] Layer thickness: 50-80μm

[0098] Scanning distance: 0.1-0.15mm

[0099] Substrate temperature: 100-150℃

[0100] Laser focus: Aim at the material surface or slightly off the surface

[0101] After the outer layer is printed, cool it for 1 hour. Use a brush to gently remove the unsintered powder on the surface of the core, and then spray a layer of epoxy resin coating on the outer layer to enhance the acid and alkali resistance of the core, and finally obtain the required core sample.

[0102] Example 2 is a combination of high temperature tolerance, stable structure and strong protection. The inner layer of the core is made of aluminum nitride, whose high thermal conductivity and high temperature resistance make it perform well in extreme environments; the middle layer uses carbon fiber reinforced nylon, which has both strength and toughness and can cope with high-pressure environments; the outer layer uses stainless steel (316L) to provide better structural strength and corrosion resistance.

[0103] Example 3

[0104] (1) Core model construction: First, slice the natural rock sample and scan it layer by layer using a 3D white light scanner to obtain data on the natural structural surface. Then, the scanned data is processed using reverse analysis software to generate a 3D model file. The model file is opened using CAD drawing software, and the core is designed as a cylindrical structure with a diameter of 140 mm and a height of 200 mm. The inner, middle, and outer layers are partitioned. A 7 mm × 7 mm × 4 mm groove is reserved inside the core for embedding the micro wireless sensor. Finally, the file is saved in STL format for subsequent printing.

[0105] (2) Inner layer printing (graphite): Pour graphite powder into the feed port of the 3D printer and start setting the printing parameters. The specific parameters are as follows:

[0106] Laser power: 60-80W

[0107] Scanning speed: 2500-3000mm / s

[0108] Layer thickness: 50-100 μm

[0109] Scanning distance: 0.1-0.2mm

[0110] Substrate temperature: 80-100°C

[0111] Laser focus: Aim at the material surface or slightly off the surface

[0112] When printing to the sensor groove position, pause printing and manually embed the micro sensor. After installation, continue printing until the inner layer area is completed and cool for 10 minutes.

[0113] (3) Middle layer printing (glass-filled nylon): Spray a layer of high-temperature epoxy resin adhesive on the inner layer surface to ensure a firm bond between the middle layer and the inner layer. Replace with glass-filled nylon powder and set the printing parameters for the middle layer area as follows:

[0114] Laser power: 50-70W

[0115] Scanning speed: 2500-3000mm / s

[0116] Layer thickness: 50-100 μm

[0117] Scanning distance: 0.1-0.2mm

[0118] Substrate temperature: 80-120°C

[0119] Laser focus: Align to the material surface

[0120] Print the middle layer area, cool it for 10 minutes after completion, and spray silicone adhesive on its surface to ensure the adhesion between the middle layer and the outer layer.

[0121] (4) Outer layer printing (silicon carbide, SiC): Replace with silicon carbide powder and start printing the outer layer area. The parameters are set as follows:

[0122] Laser power: 100-120W

[0123] Scanning speed: 1500-2000mm / s

[0124] Layer thickness: 50-80μm

[0125] Scanning distance: 0.1-0.15mm

[0126] Substrate temperature: 150-200℃

[0127] Laser focus: Aim at the material surface or slightly off the surface

[0128] After printing is completed, the core is cooled for 2 hours. Use a brush to gently remove the unsintered powder on the surface of the core, and finally get a core that meets the requirements.

[0129] Example 3 is a combination of electrical insulation, light weight, high strength and wear resistance. The inner layer of the core is graphite, which has excellent electrical insulation and high temperature stability; the middle layer material is glass-filled nylon to achieve light weight and high strength; the outer layer is made of silicon carbide (SiC), which has high hardness and wear resistance and is suitable for high friction environments.

[0130] 2. Performance test of multi-layer functional coating core suitable for extreme cementing environment

[0131] The performance test data of the artificial cores prepared by Examples 1, 2 and 3 are as follows:

[0132]

[0133] It can be seen from the table that the core prepared by the present invention is fully applicable to the core flow experiment under extreme cementing conditions and the cementing two-interface performance evaluation experiment.

[0134] 3. Evaluation of cementing interface performance of the multi-layer functional coating core

[0135] Flushing test: Flushing test is a key step to verify the effect of drilling fluid and flushing fluid on the bonding effect of cementing interface during cementing. The core with multi-coating structure prepared by the present invention is used to simulate the flushing effect during cementing process, and the effect of flushing fluid on the bonding strength of cement slurry interface is tested, especially in acidic environment, to ensure the safety and long-term stability of cementing operation.

[0136] Cementing two-interface bonding strength experiment: In cementing operations, the measurement of two-interface bonding strength is crucial. The multi-layer 3D printed core prepared by the present invention simulates the bonding performance between the cement slurry and the formation interface under high temperature and high pressure environment, and the interface strength change data of the cementing system under different working conditions provides a basis for improving cementing quality.

[0137] The drilling fluid, cement slurry, water-based flushing fluid, acidic flushing fluid (3% HCl solution) and strong alkaline flushing fluid (3% NaOH solution) from a certain oil and gas well in the southwest were selected to conduct flushing experiments and cementation strength experiments on the cores. The process is as follows:

[0138] Weigh the core mass as m0, place the core in a high-temperature and high-pressure dehydration instrument at 3MPa and 90℃ for 30min, take out the core attached with drilling fluid and weigh its mass as m1; use different types of flushing fluids to flush the core attached with drilling fluid at a speed of 300r / min for 15min, weigh the core mass attached with drilling fluid after flushing as m2, and calculate the flushing efficiency η:

[0139] η=(m1-m2) / (m1-m0)

[0140] The washed core was placed in a cementing mold, and a certain amount of cement slurry was poured between the core and the mold. The core was placed in a 90°C water bath and cured for 1 and 3 days before being taken out to obtain its cementing strength S:

[0141] S=P / (πD h)

[0142] Where S is the bonding strength, MPa; P is the loading pressure when the core is detached, N; D is the core diameter, mm; h is the height of the cement sheath, mm.

[0143] The test results are shown in Tables 1 to 4.

[0144] Table 1 Test results of core flushing efficiency prepared in Example 1

[0145]

[0146] Table 2 Core flushing efficiency test results prepared in Example 2

[0147]

[0148] Table 3 Core flushing efficiency test results prepared in Example 3

[0149]

[0150] Table 4 Test results of core cementation strength prepared in Examples 1, 2, and 3

[0151]

[0152] It can be seen from the table that the flushing efficiency and bonding strength of the multi-layer functional coating core prepared by the present invention are similar to the experimental data measured using the on-site core.

[0153] In summary, the multi-layer functional coating core based on 3D printing can fully simulate the actual downhole conditions, and the experimental data is accurate and reliable. The evaluation of the changes in the two interfaces during the cementing process through the core can provide a more complete data basis for the formation of relevant theories, and also provide a scientific basis for the smooth progress of subsequent mining operations and cementing operations.

Claims

1. A 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments, comprising the following steps in sequence: (1) Select natural core samples, determine the printing area of ​​their structural surfaces, use a 3D white light scanner to scan them layer by layer, obtain data on the natural structural surfaces, process the scanned data using reverse analysis software, and generate a 3D model file; (2) Open the 3D model file generated in step (1) in the CAD software, set the shape and size of the target core, reserve a groove inside it for placing the micro sensor, divide the target core into three areas of inner layer, middle layer and outer layer in equal proportion, and the groove is located in the inner layer, thereby completing the 3D model of the target core; (3) Select the printing materials for the inner layer, middle layer and outer layer. The inner layer is the core layer, and the printing material is copper, copper alloy, aluminum nitride, graphite or polyvinylidene fluoride. The middle layer is functional, and the printing material is carbon fiber reinforced nylon, glass-filled nylon or polyetheretherketone. The outer layer is the protective layer, and the printing material is silicon nitride, silicon carbide, polytetrafluoroethylene or nickel-based alloy. (4) The 3D data of the target core is transmitted to the data processor of the 3D printer. The printing material of each layer is filled in turn by printing layer by layer, and appropriate printing parameters are set according to different printing materials. The inner layer area of ​​the target core is printed first, and the printing is paused when the reserved groove position is reached to embed the micro sensor. Then the middle layer area is printed, and finally the outer layer area is printed to form a complete core.

2. The 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments according to claim 1, characterized in that: In the step (2), the shape of the target core may be a cuboid, a cube or a cylinder. For a cuboid or a cube core, the length, width and height ranges are 15-200 mm, 15-200 mm and 15-300 mm respectively; for a cylindrical core, the diameter is 15-200 mm and the height is 15-300 mm.

3. The 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments according to claim 1, characterized in that: In the step (2), the size of the groove is 7 mm×7 mm×4 mm, which is used to embed a standard micro sensor.

4. The 3D printing method of a multi-layer functional coating core suitable for extreme cementing environments according to claim 1, characterized in that: In the step (4), in order to ensure the firm bonding and structural stability between the inner layer and the middle layer, and between the middle layer and the outer layer of the target core, the surface of the material needs to be processed accordingly.

5. The 3D printing method of a multi-layer functional coating core suitable for extreme cementing environments according to claim 4, characterized in that: The corresponding treatment of the material surface refers to selecting corresponding adhesives according to the bonding requirements of different materials. For the bonding area between metal materials and polymers, epoxy resin or polyurethane adhesives are selected; for the bonding area between polymers and ceramic materials or graphite, high-temperature epoxy resin or silicone adhesives are selected.

6. The 3D printing method of a multi-layer functional coating core suitable for extreme cementing environments according to claim 5, characterized in that: In the bonding area between the metal material and the polymer, the roughness of the metal material surface is increased by mechanical grinding and sandblasting, thereby enhancing the adhesion of the adhesive.

7. The 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments according to claim 1, characterized in that: In the step (4), printing layer by layer means first adding the printing material of the inner layer of the core into the material guide port of the 3D printer, setting the printing parameters, and after the inner layer is printed, removing the inner layer printing material and replacing it with the printing material of the middle layer, resetting the printing parameters according to the characteristics of the middle layer material, and starting the printing of the middle layer area. After the middle layer is printed, replacing the material and adjusting the printing parameters according to the same process, and finally completing the printing of the outer layer area.

8. The 3D printing method for a multi-layer functional coating core suitable for extreme cementing environments according to claim 1, characterized in that: In the step (4), after the complete core is formed, the outer surface of the core needs to be treated according to the specific application requirements of the core. When used in a strong acid or strong alkali environment, a layer of epoxy resin coating is sprayed on the outer surface of the core; when used in a high friction or high flow rate liquid environment, a layer of polytetrafluoroethylene coating is sprayed on the outer surface of the core.

Images