Acoustic contrast particle and preparation method and application thereof

Abstract

The invention provides acoustic contrast particles as well as a preparation method and application thereof. The acoustic contrast particle comprises a solid core, an elastic middle layer and a shell layer, the solid core is coated with the elastic middle layer, the elastic middle layer is coated with the shell layer, the density of a solid core material is larger than or equal to 3 g / cm < 3 >, the elastic modulus of a middle elastic layer material is smaller than 1 GPa, and the shell layer is made of resin. Aiming at the problems that a spray drying method for preparing acoustic material particles is low in granulation speed, high in energy consumption and high in selection requirement on elastic layer materials, an acoustic contrast material particle formula and a processing technology are redesigned, and an elastic middle layer comprises elastic filling powder particles and an elastic adhesive material; the preparation efficiency of the acoustic material particles is improved by using a dusting and coating process; the complexity of the processing technology is reduced, the selection range of the elastic material is expanded, and the overall temperature resistance of the particles is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas, and more specifically, to an acoustic imaging particle for wellbore integrity monitoring, its preparation method, and its application. Background Technology

[0002] Wellbore integrity is crucial for sealing formation fluids and preventing leakage in oil and gas wells, and is key to ensuring well lifespan and environmental safety. Failure of wellbore integrity can lead to annular pressure anomalies from oil and gas originating from or outside the producing formation, often manifesting as annular pressure. According to statistics from the U.S. Mineral Management Service, in the Gulf of Mexico, 6,692 out of approximately 15,500 wells (43%) exhibit annular pressure at least once in the casing, totaling 10,153 different annular pressure layers. Wellbore integrity failure can also cause casing damage and even trigger well kicks and blowouts. Traditional wellbore integrity monitoring technology is sonic logging, which has since evolved into sonic variable density logging. Its drawbacks are similar to seismic monitoring, primarily the high cost and low accuracy of the detectors.

[0003] CN114707603A discloses a method for predicting wellbore integrity, comprising the following steps: collecting basic data 1 of oil and gas wells with existing wellbore integrity evaluation conclusions and basic data 2 of a target well, and processing the two types of basic data; the two wells have the same well type, and the two types of basic data contain the same parameter types; using the wellbore integrity evaluation conclusions as the dependent variable for oil and gas wellbore integrity evaluation, and using the basic data as the independent variable for oil and gas wellbore integrity evaluation; based on the dependent and independent variables, using a random forest algorithm, employing random sampling with replacement to extract training data, and constructing a decision tree and a random forest; placing the basic data 2 of the target well into the decision tree and random forest to obtain the wellbore integrity evaluation conclusion of the target well. This invention can predict the wellbore integrity of a target well without affecting oil and gas well production, reducing the cost of wellbore integrity testing.

[0004] CN106499385A provides an apparatus and method for evaluating casing integrity under fracturing conditions. The apparatus includes: a sealed cavity in which a wellbore, comprising rock mass and casing, is attached, with a cement annulus formed between the casing and the rock mass; a stress supply mechanism including two pressure plates disposed within the cavity and attached to the rock mass; a temperature control mechanism including a copper core rod and a liquid nitrogen tank, one end of the copper core rod being inserted into the casing and the other end connected to a heating platform, the liquid nitrogen tank being connected to both the casing and the cement annulus; a pressure supply mechanism including a first hydraulic pump connected to the casing and a second hydraulic pump connected to the cement annulus; and a measuring mechanism including a gas flow meter electrically connected to a calculation and processing unit, three sets of strain gauges, and three sets of thermocouples, the gas flow meter being connected to the cement annulus. This invention can realistically simulate the wellbore fracturing environment and accurately and quantitatively evaluate wellbore integrity.

[0005] CN109083632A relates to an integrated CBL and SBT logging simulation experimental device and method, comprising a main probe cylinder, a probe, a wall probe box moving block, a push arm, and an inner probe box. The main probe cylinder is disposed outside the cylindrical probe. The wall probe box moving block and the push arm are disposed inside the probe. The push arm is connected to the wall probe box moving block, and the push arm and the wall probe box moving block form a sliding mechanism that moves up and down inside the main probe cylinder. The inner probe box is disposed at both the upper and lower parts inside the probe, and the inner probe box is filled with coupling agent to protect the probe. This invention can perform CBL logging and SBT logging simultaneously, and can not only perform overall evaluation of cementing quality, but also sector-by-sector evaluation, qualitatively and quantitatively evaluating the cementing quality at a specific azimuth. Summary of the Invention

[0006] The design of acoustic composite particle structures is based on the strong reflection of local resonance of phonon crystals within a certain frequency range, which can be used to monitor wellbore integrity.

[0007] Currently, spray drying is the main method used to prepare acoustic material particles. The main problems are slow granulation speed, high energy consumption, and high requirements for the selection of elastic layer materials. For example, the elastic layer material must be easily soluble in the dispersion solvent, or even an organic solvent must be used. The viscosity of the material cannot be too high. The elastic materials that can be selected are either complicated to process or have poor high temperature resistance, which greatly limits the preparation of acoustic composite materials.

[0008] To address the problems existing in the prior art, this invention proposes an acoustic imaging particle and its preparation method.

[0009] One objective of this invention is to provide an acoustic imaging particle comprising: a solid core, an elastic intermediate layer covering the solid core, and an outer shell layer covering the elastic intermediate layer, wherein the density of the solid core material is greater than or equal to 3 g / cm³. 3 The elastic modulus of the intermediate elastic layer material is less than 1 GPa, and the outer shell material is resin.

[0010] According to a preferred embodiment of the present invention, the particle size of the acoustic imaging particles is 0.5 to 1.5 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, etc.

[0011] According to a preferred embodiment of the present invention, the solid core is selected from at least one of ceramic, metal, and alloy materials.

[0012] According to a more preferred embodiment of the present invention, the solid core is iron.

[0013] According to a preferred embodiment of the present invention, the particle size of the solid core is 0.2 to 0.6 mm, for example, it can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc.

[0014] According to a preferred embodiment of the present invention, the elastic interlayer material comprises elastic filler powder particles and elastic adhesive material.

[0015] According to a preferred embodiment of the present invention, the elastic filler powder particles are selected from at least one of rubber and rubber-like materials, more preferably from at least one of polyurethane elastomers, fluorinated rubbers, and elastic epoxy resins.

[0016] According to a preferred embodiment of the present invention, the elastic adhesive material is selected from at least one of waterborne polyurethane elastomer and phenolic resin.

[0017] According to a preferred embodiment of the present invention, the thickness of the elastic intermediate layer is 0.1 to 0.6 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc.

[0018] According to a preferred embodiment of the present invention, the resin is selected from at least one of phenolic resin and epoxy resin.

[0019] According to a preferred embodiment of the present invention, the thickness of the outer shell layer is 0.05 to 0.2 mm, for example, it can be 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0020] Under external stress conditions, acoustic imaging particles undergo extrusion deformation due to their elasticity, which changes their structural parameters and the resonant acoustic frequency of the particle structure, thus affecting their acoustic performance. They can be used in wellbores to monitor wellbore integrity based on the acoustic frequency band characteristics obtained from acoustic logging.

[0021] The second objective of this invention is to provide a method for preparing the acoustic imaging particles described above, comprising spraying an elastic intermediate layer material onto the surface of a solid core, forming an elastic intermediate layer, and then spraying an outer shell material solution to obtain the acoustic imaging particles.

[0022] According to a preferred embodiment of the present invention, the elastic interlayer material comprises elastic filler powder particles and an elastic adhesive material.

[0023] According to a preferred embodiment of the present invention, the elastic filler powder particles are selected from at least one of rubber and rubber-like materials, more preferably from at least one of polyurethane elastomers, fluorinated rubbers, and elastic epoxy resins.

[0024] According to a preferred embodiment of the present invention, the elastic adhesive material is selected from at least one of waterborne polyurethane elastomer and phenolic resin.

[0025] According to a preferred embodiment of the present invention, the particle size of the elastic filler powder is 120-300 mesh, the viscosity of the elastic adhesive material is less than 500 mPa·s, and the solid content of the elastic adhesive material is more than 30 wt%.

[0026] More preferably, the particle size of the elastic filler powder is 180-250 mesh, the viscosity of the elastic adhesive material is 100-350 mPa·s, and the solid content of the elastic adhesive material is 35-45 wt%.

[0027] According to a preferred embodiment of the present invention, a centrifugal powder coating process is used in the process of spraying the elastic intermediate layer material.

[0028] Preferably, the fan power is 0.4 to 1.2 kW, the turntable speed is 200 to 380 rpm, the spraying rate of the elastic adhesive material is 1 to 4 ml / min, the addition rate of the elastic filler powder particles is 0.5 to 4 g / min, and the heating temperature is 75 to 95℃.

[0029] More preferably, the fan power is 0.5 to 1 kW, the turntable speed is 230 to 350 rpm, the spraying rate of the elastic adhesive material is 2 to 3 ml / min, the addition rate of the elastic filler powder particles is 1 to 3 g / min, and the heating temperature is 80 to 90℃.

[0030] More preferably, the fan power is 0.7-0.9kW, the turntable speed is 280-320rpm, the spraying rate of the elastic adhesive material is 2.5-2.7ml / min, the addition rate of the elastic filler powder particles is 2-2.5g / min, and the heating temperature is 85-87℃.

[0031] According to a preferred embodiment of the present invention, a centrifugal powder coating process is used during the spraying of the outer shell material solution.

[0032] Preferably, the solvent for the outer shell material solution can be an alcohol, such as ethanol.

[0033] Preferably, the fan power is 0.5 to 1.6 kW, the outer shell material solution spraying rate is 0.2 to 1.5 ml / min, and the heating temperature is 55 to 75°C.

[0034] Preferably, the fan power is 0.9 to 1.2 kW, the coating material solution spraying rate is 0.3 to 1 ml / min, and the heating temperature is 60 to 70°C.

[0035] More preferably, the fan power is 1 to 1.1 kW, the coating material solution spraying rate is 0.5 to 0.7 ml / min, and the heating temperature is 65 to 68°C.

[0036] The third objective of this invention is to provide the application of the acoustic imaging particles or the acoustic imaging particles obtained by the preparation method in wellbore integrity monitoring.

[0037] The acoustic imaging particles of this invention comprise a solid high-density core, an elastic intermediate layer material, and an outer hard shell. This allows the acoustic imaging particles to emit sound waves in specific frequency bands under different stress conditions. Based on the sound wave frequency band characteristics obtained from acoustic logging, the location and stress intensity of abnormal stress points can be obtained, and the well casing deformation can be accurately calculated. In areas where the risk of casing deformation is judged to be high, measures such as optimizing the wellbore orientation, improving cementing quality, appropriately reducing the discharge rate, and using temporary plugging technology can be considered to reasonably control the fluid pressure in the fracture and reduce the risk of casing deformation.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] This invention can improve the preparation efficiency of acoustic imaging particles, with each batch of samples weighing 3-5 kg, reducing the preparation time from 22-24 hours to 2-3 hours, reducing the amount of organic solvent used, increasing the particle temperature resistance from 120℃ to 180℃, and reducing the preparation energy consumption by more than half. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the acoustic imaging particles of the present invention.

[0041] Among them, 1-solid core; 2-elastic adhesive material; 3-elastic filling powder particles; 4-outer shell layer.

[0042] Figure 2 This is a schematic diagram of the structure of the particles in Comparative Example 1.

[0043] Among them, 1-solid core; 5-elastic intermediate layer; 4-outer shell layer.

[0044] Figure 3 This is a process flow diagram of the present invention for preparing acoustic imaging particles using a powder coating process.

[0045] Figure 4 This is a comparison curve of acoustic penetration of the imaging wellbore and the ordinary wellbore, representing the acoustic performance of the present invention.

[0046] from Figure 4 As can be seen, the angiography wellbore with added acoustic angiography particles from Example 1 has a higher penetration loss than the ordinary wellbore and a higher ability to identify incomplete locations in the wellbore. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0048] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0049] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0050] According to a preferred embodiment of the present invention, the acoustic imaging particles comprise a three-layer structure, such as... Figure 1 As shown, they are a high-density solid core, an elastic intermediate layer, and a rigid protective outer shell, respectively. The elastic intermediate layer includes elastic filler powder particles and elastic adhesive material.

[0051] For hard solid cores, materials with high density can be selected, with a density requirement of 3 g / cm³ or greater. 3 The main categories include ceramics, metals and alloys, with iron being the preferred material.

[0052] The elastic interlayer can be made of materials with low Young's modulus and sound velocity, with an elastic modulus requirement of less than 1 GPa, mainly rubber and rubber-like materials.

[0053] The elastic interlayer material is preferably a water-based polyurethane elastomer binder or a phenolic resin binder, as well as polyurethane elastomer powder such as thermoplastic polyurethane elastomer powder or other rubber or rubber-like powder. The elastic powder is required to be 120-300 mesh, the viscosity of the elastic adhesive material is required to be below 500 mPa·s, and the solid content is above 30 wt%.

[0054] The rigid outer shell material is generally selected from protective materials with good temperature resistance, stable properties, and a certain degree of pressure resistance, mainly resin materials. Phenolic resin or epoxy resin is preferred, with a temperature resistance of over 150℃.

[0055] To reduce the use of organic solvents such as tetrahydrofuran and improve the efficiency of acoustic imaging particle preparation, it is preferable to modify the fluidized bed process into a centrifugal powder coating process.

[0056] The centrifugal powder coating process can be carried out using equipment commonly used in the field, such as a centrifugal powder coating machine.

[0057] According to a preferred embodiment of the present invention, the centrifugal powder coating process includes the following steps:

[0058] Elastic intermediate layer material coating: the fan power is 0.4~1.2kW, the turntable speed is 200~380rpm, the spraying rate of the elastic adhesive material is 1~4ml / min, the addition rate of the elastic filler powder particles is 0.5~4g / min, and the heating temperature is 75~95℃, to ensure that the elastic layer material dries and solidifies rapidly on the surface of the core particles and the particles are dispersed.

[0059] Rigid outer shell material coating: fan power is 0.5~1.6kW, outer shell layer material solution spraying rate is 0.2~1.5ml / min, heating temperature is 55~75℃.

[0060] This invention can improve preparation efficiency, reduce the preparation time from 22-24 hours to 2-3 hours, increase the temperature resistance of particles from 120℃ to 180℃, and reduce preparation energy consumption by more than half.

[0061] In the example:

[0062] The waterborne polyurethane of the elastic interlayer is waterborne polyurethane 1926F0402 produced by Shenzhen Yoshida Chemical Co., Ltd., with a solid content of 32wt%, viscosity of less than 350mPa·s, and elastic modulus of about 1.3MPa.

[0063] The TPU powder is BASF 200 mesh TPU powder from Shanghai Kaiyang Plastics Co., Ltd.

[0064] The epoxy resin for the outer hard shell is AG80 tetrafunctional high-temperature resistant epoxy resin produced by Kailuwei Chemical Co., Ltd.

[0065] Example 1

[0066] A method for preparing a powder coating device for composite materials specifically includes the following steps:

[0067] Elastic layer material coating: Core iron ball particle size 0.5mm, 2kg. Fan power controlled at 0.5kW, turntable speed 230rpm to ensure core particles are in a rolling state, water-based polyurethane elastomer binder spraying rate controlled at 2ml / min, TPU powder addition rate at 1g / min, heating temperature 80℃. Powder coating for 2 hours. After elastic layer coating, particle size is 0.89mm.

[0068] Rigid shell material coating: Based on the above particles, a rigid shell material coating is carried out. The fan power is controlled at 0.9kW, the epoxy resin ethanol solution spraying rate is controlled at 0.3ml / min, and the heating temperature is 60℃. Coating is carried out for 30 minutes, and the final particle size is 0.95mm.

[0069] The finished product is 3.8 kg, takes 2.5 hours, consumes 30 kWh of energy, and the material is heat resistant to 150℃.

[0070] Example 2

[0071] A method for preparing a powder coating device for composite materials specifically includes the following steps:

[0072] Elastic layer material coating: Core iron ball particle size 0.5mm, 2kg. Fan power controlled at 1kW, turntable speed 350rpm to ensure core particles are in a rolling state, water-based polyurethane elastomer adhesive spraying rate controlled at 3ml / min, TPU powder addition rate at 3g / min, heating temperature 90℃. Powder coating for 1.5h. After elastic layer coating, particle size is 0.95mm.

[0073] Rigid shell material coating: Based on the above particles, a rigid shell material coating is carried out. The fan power is controlled at 1.2kW, the epoxy resin ethanol solution spraying rate is controlled at 1ml / min, and the heating temperature is 70℃. Coating time is 15min, and the final particle size is 1.1mm.

[0074] The finished product is 4.2 kg, takes 1.75 h to produce, consumes 25 kWh of energy, and the material is heat resistant to 150℃.

[0075] Comparative Example 1

[0076] A method for preparing a spray drying device for composite materials specifically includes the following steps:

[0077] Elastic layer material coating: Core iron ball particle size 0.5mm, 1kg. Fan power controlled at 1.4kW to ensure core particles are in a fluidized state. Elastic layer solution (water-based polyurethane elastomer binder) spraying rate controlled at 0.5ml / min. Heating temperature 80℃ to ensure elastic layer material dries and solidifies rapidly on the surface of core particles; otherwise, bed collapse may occur. Coating for 12 hours. After elastic layer coating, particle size is 0.89mm.

[0078] Coating of rigid outer shell material: Fan power controlled at 1.2kW, epoxy resin ethanol solution spraying rate controlled at 0.3ml / min, heating temperature 60℃. Coating time 30min, final particle size 0.95mm.

[0079] The finished product is 1.8 kg, takes 12.5 hours, consumes 260 kWh of energy, and the material is heat resistant to 120℃.

[0080] Comparative Example 2

[0081] A method for preparing a powder coating device for composite materials specifically includes the following steps:

[0082] Elastic layer material coating: Core iron ball particle size 0.5mm, 2kg. Fan power controlled at 0.5kW, turntable speed 230rpm to ensure core particles are in a rolling state, water-based polyurethane elastomer adhesive spraying rate controlled at 2ml / min, heating temperature 80℃. Powder coating for 2 hours.

[0083] 85% of the particles clumped together, resulting in only 15% of the particles meeting the requirements. Furthermore, the particle size was uneven, ranging from 0.7mm to 1.3mm. The processing failed.

[0084] This invention addresses the problems of slow granulation speed, high energy consumption, and stringent requirements for the selection of elastic layer materials when using spray drying to prepare acoustic material particles. It redesigns the formulation and processing technology of acoustic imaging material particles. The elastic intermediate layer includes elastic filler powder particles and elastic adhesive material. A powder coating process is used to improve the preparation efficiency of acoustic material particles, reduce the complexity of the processing technology, expand the selection range of elastic materials, and improve the overall temperature resistance of the particles.

[0085] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

[0086] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0087] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0088] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0089] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0090] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0091] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. An acoustic imaging particle comprising: The material comprises a solid core, an elastic intermediate layer covering the solid core, and an outer shell layer covering the elastic intermediate layer, wherein the density of the solid core material is greater than or equal to 3 g / cm³. 3 The elastic modulus of the intermediate elastic layer material is less than 1 GPa, and the outer shell material is resin.

2. The acoustic imaging particles according to claim 1, characterized in that: The particle size of the acoustic imaging particles is 0.5–1.5 mm.

3. The acoustic imaging particles according to claim 1, characterized in that: The solid core is selected from at least one of ceramic, metal, and alloy materials, preferably iron; and / or, The particle size of the solid core is 0.2 to 0.6 mm.

4. The acoustic imaging particles according to claim 1, characterized in that: The elastic interlayer material comprises elastic filler powder particles and elastic adhesive material, preferably, The elastic filler powder particles are selected from at least one of rubber and rubber-like materials, more preferably from at least one of polyurethane elastomers, fluorinated rubbers, and elastic epoxy resins; and / or, the elastic adhesive material is selected from at least one of waterborne polyurethane elastomers and phenolic resins; and / or The thickness of the elastic intermediate layer is 0.1 to 0.6 mm.

5. The acoustic imaging particles according to claim 1, characterized in that: The resin is selected from at least one of phenolic resin and epoxy resin; and / or The thickness of the outer shell layer is 0.05 to 0.2 mm.

6. A method for preparing acoustic imaging particles according to any one of claims 1 to 5, comprising spraying an elastic intermediate layer material onto the surface of a solid core, forming an elastic intermediate layer, and then spraying an outer shell material solution to obtain the acoustic imaging particles.

7. The preparation method according to claim 6, characterized in that: The elastic intermediate layer material comprises elastic filler powder particles and elastic adhesive material; preferably, the particle size of the elastic filler powder particles is 120-300 mesh, the viscosity of the elastic adhesive material is less than 500 mPa·s, and the solid content of the elastic adhesive material is more than 30 wt%; more preferably, the particle size of the elastic filler powder particles is 180-250 mesh, the viscosity of the elastic adhesive material is 100-350 mPa·s, and the solid content of the elastic adhesive material is 35-45 wt%.

8. The preparation method according to claim 6, characterized in that: During the application of the elastic intermediate layer material, a centrifugal powder coating process is used. Preferably, the fan power is 0.4 to 1.2 kW, the turntable speed is 200 to 380 rpm, the spraying rate of the elastic adhesive material is 1 to 4 ml / min, the addition rate of the elastic filler powder particles is 0.5 to 4 g / min, and the heating temperature is 75 to 95℃. More preferably, the fan power is 0.5 to 1 kW, the turntable speed is 230 to 350 rpm, the spraying rate of the elastic adhesive material is 2 to 3 ml / min, the addition rate of the elastic filler powder particles is 1 to 3 g / min, and the heating temperature is 80 to 90℃.

9. The preparation method according to claim 6, characterized in that: During the process of spraying the outer shell material solution, a centrifugal powder coating process is adopted; Preferably, the fan power is 0.5 to 1.6 kW, the outer shell material solution spraying rate is 0.2 to 1.5 ml / min, and the heating temperature is 55 to 75°C; More preferably, the fan power is 0.9 to 1.2 kW, the outer shell material solution spraying rate is 0.3 to 1 ml / min, and the heating temperature is 60 to 70°C.

10. The application of the acoustic imaging particles according to any one of claims 1 to 5 or the acoustic imaging particles obtained by the preparation method according to any one of claims 6 to 9 in wellbore integrity monitoring.

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