Long-acting slow-release controllable scale inhibitor for oil field and application thereof

Abstract

This invention discloses a long-acting, slow-release, controllable scale inhibitor for oilfield use, comprising the following components by weight percentage: 5.0–40.0% organophosphorus, 40.0–80.0% slow-release carrier, 5.0–25.0% filler, 1.0–5.0% synergist, and 1.0–5.0% plasticizer, totaling 100%. The organophosphorus is selected from at least one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediaminetetramethylenephosphonic acid, and disodium hydroxyethylidene diphosphonate. The slow-release carrier is selected from at least one of polyacrylic acid, polymaleic anhydride, polybutylene terephthalate, polyurethane, polyamide, and polylactic acid. The synergist is a composite system of perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer. The organophosphorus, slow-release carrier, filler, synergist, and plasticizer are first blended, then the mixture is added to a twin-screw extruder for melt plasticizing extrusion, cooling, granulation, and sieving to obtain scale inhibitor particles. This scale inhibitor exhibits excellent long-lasting slow-release properties, with an effective action time of 90 to 150 days, and its scale inhibition effect is particularly significant for calcium sulfate and calcium carbonate scale.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and in particular to a long-acting, slow-release, controllable scale inhibitor for oilfield use and its application. Background Technology

[0002] In oilfield water injection systems, various salts, such as calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, and magnesium hydroxide, are dissolved in the water. With changes in temperature, pressure, and the oil-gas-water balance, these salts readily crystallize and precipitate in the water, forming various types of scale, including calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, and magnesium hydroxide, in underground reservoirs, casings, downhole equipment, surface facilities, and gathering pipelines. The continuous accumulation of scale leads to a series of serious consequences. For example, scale buildup inside the wellbore causes blockages, significantly increasing water flow resistance. This not only reduces the injection efficiency of the oilfield water injection system but may also cause serious malfunctions such as pipeline rupture. Simultaneously, scale, along with dissolved oxygen and other substances in the water, accelerates the corrosion process of metal equipment, severely impacting its lifespan and significantly increasing maintenance costs and replacement frequency.

[0003] While various types of scale inhibitors exist on the market, most traditional scale inhibitors have significant performance shortcomings. On the one hand, conventional liquid scale inhibitors suffer from uneven dosing, rapid loss of active ingredients, and low scale inhibition efficiency. Furthermore, their effective action time is extremely limited, often requiring frequent additions, which is not only cumbersome but also significantly increases overall operating costs. On the other hand, when faced with complex water quality conditions such as high hardness (calcium hardness > 500 mg / L) and high alkalinity (total alkalinity > 300 mg / L), the scale inhibition effect of many scale inhibitors drops sharply, failing to meet the urgent need for efficient and stable scale inhibition in oil and gas extraction. Therefore, developing a new type of scale inhibitor with long-lasting slow-release properties that maintains high scale inhibition efficiency under complex water quality conditions has become a critical issue that urgently needs to be addressed in the field of oilfield water treatment. Summary of the Invention

[0004] To address the shortcomings of existing scale inhibitors for oilfields in achieving long-lasting sustained release, this invention provides a long-lasting, controlled-release scale inhibitor for oilfields.

[0005] The long-acting, slow-release, controllable scale inhibitor for oilfields provided by this invention is a long-acting, slow-release, controllable scale inhibitor made from the following components in weight percentage:

[0006] Organophosphorus 5.0–40.0%, sustained-release carrier 40.0–80.0%, filler 5.0–25.0%, synergist 1.0–5.0%, plasticizer 1.0–5.0%, total 100%.

[0007] The organophosphorus is selected from at least one of hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylene phosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMPA), and disodium hydroxyethylidene diphosphonate (HEDP·Na2).

[0008] The sustained-release carrier is selected from at least one of polybutylene terephthalate (PBT), polyurethane (PU), polyamide (PA), polylactic acid (PLA), polyacrylic acid (PAA), and polymaleic anhydride (PMA).

[0009] The filler is a natural or synthetic material with a porous structure. Preferably, the filler is any one of porous molecular sieves modified with silane coupling agents, diatomaceous earth, or porous polymer microspheres. Its large specific surface area and abundant microporous structure allow it to firmly load the effective components of the scale inhibitor through physical adsorption and chemical action, and achieve slow release through microporous diffusion upon contact with water. Furthermore, surface modification enhances its loading capacity.

[0010] The synergist is a composite system of perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer. Preferably, the perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer are composited at a mass ratio of 1:2 to 2:1. The synergist enhances the adsorption of the scale inhibitor on the metal surface by reducing the surface tension of water, and at the same time, the synergist complexes with impurity ions in the water, reducing interference with the performance of the scale inhibitor.

[0011] The plasticizer is at least one of glycerol, triethylene glycol, and N-methylpyrrolidine. The main function of the plasticizer is to improve the compatibility between the filler and the slow-release carrier during the melt plasticization process, effectively balancing the toughness of the slow-release carrier with the high strength of the inorganic filler, thus giving the scale inhibitor good molding and processing properties.

[0012] The preparation method of the long-acting slow-release controllable scale inhibitor for oil fields is as follows: First, organophosphorus compounds, slow-release carriers, fillers, synergists and plasticizers are mixed and stirred evenly. Then, the mixture is added to a twin-screw extruder for melt plasticizing and extrusion, cooling and granulation to obtain scale inhibitor particles.

[0013] Specifically, the conditions for melt plasticizing extrusion are: feed section temperature of the twin-screw extruder 40-60℃, melt section temperature 120-180℃, compression section temperature 140-200℃ and metering section temperature 180-220℃, and melt plasticizing time 2-6 min.

[0014] Preferably, the scale inhibitor particles have a particle size of 1-2 mm and a density of 1.30-1.50 g / cm³. 3 .

[0015] This scale inhibitor is mainly used in environments with formation temperatures ranging from 30℃ to 150℃.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] (1) The long-acting slow-release controllable scale inhibitor of the present invention has a synergistic effect: It employs an organophosphorus scale inhibitor, whose active groups such as phosphorus-oxygen double bonds (P=O), hydroxyl groups (-OH), and amino groups (-NH2) in the molecular structure chelate with metal ions such as calcium, magnesium, and barium in water to form stable water-soluble chelates, thereby preventing scale precipitation. The -COOH, -OH, and -NH2 groups in the slow-release carrier molecular structure adsorb onto the surface of scale crystal growth. Through the synergistic effect of carboxylic acid group ionization and lattice distortion, normal crystal growth is interfered with, causing the scale to exist in the form of tiny dispersed particles. This increases the dissolution rate and efficiency of metal ions such as calcium, magnesium, and barium, thus playing a synergistic role in scale inhibition.

[0018] (2) The scale inhibitor of this invention has long-lasting and controllable slow-release properties: This invention utilizes polymer composite material extrusion molding technology to successfully construct a highly efficient polymer composite material slow-release controllable system. Furthermore, by adjusting the types of slow-release carriers used, the solubility of the scale inhibitor at different temperatures can be altered, resulting in scale inhibitors suitable for various temperature environments and meeting diverse on-site construction requirements. Compared to traditional scale inhibitors, its effective component can be released slowly for 90–150 days. In practical applications, it can significantly reduce the number of times and dosage of scale inhibitors are added, lowering labor and material costs. Moreover, it can solve scaling problems in the entire injection, production, and flooding system, improving the stability and reliability of water system operation.

[0019] (3) The long-acting slow-release controllable scale inhibitor of the present invention has high scale inhibition performance: the synergistic effect of organophosphorus compounds and polyester acid and polyurethane polymers endows the scale inhibitor with excellent scale inhibition performance. Under complex water quality conditions, especially in complex water quality environments with high hardness (calcium hardness > 500 mg / L) and high alkalinity (total alkalinity > 300 mg / L), through chelation, lattice distortion and synergistic effect of synergists, it can effectively inhibit the formation and deposition of scale. The scale inhibition rate of CaCO3 and CaSO4 can reach more than 80%, which is significantly better than most traditional scale inhibitor products on the market; moreover, the applicable formation temperature of the scale inhibitor is 30℃~150℃.

[0020] (4) Environmental and Safety Characteristics: The raw materials used in this invention are all environmentally friendly substances with complete solubility. They will not cause secondary pollution to the environment during production, use, and discharge. Simultaneously, they have no corrosive effect on metal equipment, effectively protecting the metal surface of production equipment, extending equipment lifespan, and reducing equipment maintenance costs, resulting in good economic and environmental benefits. Compared with liquid scale inhibitors, the effective components of solid particle slow-release scale inhibitors can be slowly released directly into the produced fluid at the bottom of the well without the need for a dosing pump. Solid particle long-acting slow-release controllable scale inhibitors have regular shapes and uniform surface areas, allowing for stable release of effective components. They are not easily carried away by liquids or gas streams, resulting in high scale inhibition efficiency. By extending the duration of action of the effective components, the volatilization, loss, and decomposition of chemical substances are significantly reduced, thereby improving the utilization efficiency of the agent and mitigating environmental pollution. Using solid particle scale inhibitors for dosing can significantly reduce the frequency of personnel contact with chemicals, thereby effectively preventing chemical injuries and chemical spills.

[0021] (5) Simple production and construction process: The long-acting slow-release controllable scale inhibitor of the present invention adopts the composite polymer material melt extrusion molding, cooling, pelletizing and screening process. The preparation method is simple and easy to industrialize and produce on a large scale. It has the advantages of convenient construction, injection operation and maintenance, low injection cost, and the ability to maintain good scale inhibition effect for a long time. It has good economic promotion value.

[0022] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 The graph shows the solubility and scale inhibition rate of the long-acting slow-release controllable scale inhibitor prepared in Example 1 at 30–60°C as a function of dissolution time.

[0024] Figure 2 The graph shows the solubility and scale inhibition rate of the long-acting slow-release controllable scale inhibitor prepared in Example 2 at 60–90°C as a function of dissolution time.

[0025] Figure 3 The graph shows the solubility and scale inhibition rate of the long-acting slow-release controllable scale inhibitor prepared in Example 3 at 90–120°C as a function of dissolution time.

[0026] Figure 4 The graph shows the solubility and scale inhibition rates of the long-acting, slow-release, controllable scale inhibitor prepared in Example 4 at 120–150°C as a function of dissolution time. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] Example 1

[0029] A long-acting, slow-release, controllable scale inhibitor suitable for reservoirs at 30–60°C, comprising the following components by weight percentage:

[0030] Organophosphorus compounds: 10.0% hydroxyethylidene diphosphonic acid, 10.0% aminotrimethylene phosphonic acid, and 10.0% disodium hydroxyethylidene diphosphonate; Sustained-release carrier: 20.0% polyacrylic acid, 10.0% polymaleic anhydride, and 15.0% polybutylene terephthalate; Filler: 10% silane coupling agent-modified porous molecular sieve and 5.0% silane coupling agent-modified diatomaceous earth; Synergist: 5.0% of a composite system of potassium perfluorooctane sulfonate and maleic acid-acrylic acid copolymer at a mass ratio of 1:2; Plasticizer: 1.5% glycerol, 2.0% triethylene glycol, and 1.5% N-methylpyrrolidine. The silane coupling agent modification method involves soaking porous molecular sieves or diatomaceous earth in an aqueous solution containing the silane coupling agent for 30 minutes, followed by drying.

[0031] The preparation method of the long-acting, slow-release, controllable scale inhibitor includes the following steps:

[0032] (1) After weighing the materials as described above, pour them into the mixer and mix for 30 minutes until they are evenly mixed.

[0033] (2) Melt extrusion: The mixture is added to a twin-screw extruder for melt plasticizing and extrusion. The temperature of the twin-screw extruder is 40℃ in the feed section, 140℃ in the melting section, 150℃ in the compression section and 185℃ in the metering section. The melt plasticizing time is 5min. The die diameter of the extruder is 2.0mm.

[0034] (3) Cooling: Air cooling, temperature is 20-35℃;

[0035] (4) Pelletizing and sieving: to obtain a long-acting slow-release controllable scale inhibitor with a particle size of 1-2 mm.

[0036] Example 2

[0037] A long-acting, slow-release, controllable scale inhibitor suitable for reservoirs at 60–90°C, comprising the following components by weight percentage:

[0038] Organophosphorus compounds: 10.0% hydroxyethylidene diphosphonic acid, 10.0% aminotrimethylene phosphonic acid, and 10.0% disodium hydroxyethylidene diphosphonate; Sustained-release carrier: 10.0% polyacrylic acid, 15.0% polymaleic anhydride, and 20.0% polyamide; Filler: 10% silane coupling agent-modified porous molecular sieve and 5.0% silane coupling agent-modified diatomaceous earth; Synergist: 5.0% of a composite system of potassium perfluorooctane sulfonate and maleic acid-acrylic acid copolymer at a mass ratio of 1:2; Plasticizer: 1.5% glycerol, 2.0% triethylene glycol, and 1.5% N-methylpyrrolidine. The silane coupling agent modification method involves soaking porous molecular sieves or diatomaceous earth in an aqueous solution containing the silane coupling agent for 30 minutes, then removing and drying.

[0039] The preparation method of the long-acting slow-release controllable scale inhibitor is the same as in Example 1.

[0040] Example 3

[0041] A long-acting, slow-release, controllable scale inhibitor suitable for reservoirs at 90–120°C, comprising the following components by weight percentage:

[0042] Organophosphorus compounds: 10.0% hydroxyethylidene diphosphonic acid, 10.0% aminotrimethylene phosphonic acid, and 10.0% disodium hydroxyethylidene diphosphonate; Sustained-release carrier: 20.0% polyurethane, 20.0% polylactic acid, and 10.0% polyacrylic acid; Filler: 5% silane coupling agent-modified porous molecular sieve and 5.0% silane coupling agent-modified diatomaceous earth; Synergist: 5.0% of a composite system of potassium perfluorooctane sulfonate and maleic acid-acrylic acid copolymer at a mass ratio of 1:2; Plasticizer: 1.5% glycerol, 2.0% triethylene glycol, and 1.5% N-methylpyrrolidine. The silane coupling agent modification method involves soaking porous molecular sieves or diatomaceous earth in an aqueous solution containing the silane coupling agent for 30 minutes, then removing and drying.

[0043] The preparation method of the long-acting slow-release controllable scale inhibitor is the same as in Example 1.

[0044] Example 4

[0045] A long-acting, slow-release, controllable scale inhibitor suitable for reservoirs at 120–150°C, comprising the following components by weight percentage:

[0046] Organic phosphine scale inhibitor: disodium hydroxyethylidene diphosphonate 25.0%; slow-release carrier: polyurethane 35.0%, polylactic acid 20.0%, polyacrylic acid 5.0%; filler: diatomaceous earth 5.0%; synergist: potassium perfluorobutane sulfonate and maleic acid-acrylic acid copolymer in a mass ratio of 2:1 5.0%; plasticizer: glycerin 3.0%, N-methylpyrrolidone 2.0%.

[0047] The preparation method of the long-acting, slow-release, controllable scale inhibitor includes the following steps:

[0048] (1) After weighing the materials as described above, pour them into the mixer and mix for 30 minutes until they are evenly mixed.

[0049] (2) Melt extrusion: The mixture is added to a twin-screw extruder for melt plasticizing and extrusion. The temperature of the twin-screw extruder is 40℃ in the feed section, 155℃ in the melting section, 180℃ in the compression section and 210℃ in the metering section. The melt plasticizing time is 5min. The die diameter of the extruder is 2.0mm.

[0050] (3) Cooling: Air cooling, temperature is 20-35℃;

[0051] (4) Pelletizing and sieving: to obtain a long-acting slow-release controllable scale inhibitor with a particle size of 1-2 mm.

[0052] Comparative Example 1

[0053] Based on Example 1, the synergist was directly removed to prepare scale inhibitor particles. Details are as follows:

[0054] A long-acting, slow-release, controllable scale inhibitor suitable for reservoirs at 30–60°C, comprising the following components by weight percentage:

[0055] Organophosphorus compounds: 10.0% hydroxyethylidene diphosphonic acid, 10.0% aminotrimethylene phosphonic acid, and 10.0% disodium hydroxyethylidene diphosphonate; Sustained-release carrier: 20.0% polyacrylic acid, 10.0% polymaleic anhydride, and 15.0% polybutylene terephthalate; Filler: 10% silane coupling agent-modified porous molecular sieve and 5.0% silane coupling agent-modified diatomaceous earth; Plasticizer: 1.5% glycerol, 2.0% triethylene glycol, and 1.5% N-methylpyrrolidine. The silane coupling agent modification method involves soaking the porous molecular sieve or diatomaceous earth in an aqueous solution containing the silane coupling agent for 30 minutes, then removing and drying it.

[0056] The preparation method of the long-acting, slow-release, controllable scale inhibitor includes the following steps:

[0057] (1) After weighing the materials as described above, pour them into the mixer and mix for 30 minutes until they are evenly mixed.

[0058] (2) Melt extrusion: The mixture is added to a twin-screw extruder for melt plasticizing and extrusion. The temperature of the twin-screw extruder is 40℃ in the feed section, 140℃ in the melting section, 150℃ in the compression section and 185℃ in the metering section. The melt plasticizing time is 5min. The die diameter of the extruder is 2.0mm.

[0059] (3) Cooling: Air cooling, temperature is 20-35℃;

[0060] (4) Pelletizing and sieving: to obtain a long-acting slow-release controllable scale inhibitor with a particle size of 1-2 mm.

[0061] Comparative Example 2

[0062] Based on Example 1, the synergist was replaced with 5.0% perfluoroalkyl sulfonate. During the preparation process, it was found that it could not be processed into scale inhibitor particles.

[0063] Comparative Example 3

[0064] Based on Example 1, the synergist was replaced with 5.0% maleic acid-acrylic acid copolymer. During the preparation process, it was found that it was still impossible to process it into scale inhibitor particles.

[0065] The long-acting, slow-release, controllable scale inhibitors obtained in Examples 1-4 were subjected to indoor dissolution experiments and scale inhibition performance tests according to the standard SY / T 5673-2020 "General Technical Conditions for Scale Inhibitors for Oilfield Use". The long-acting, slow-release, controllable scale inhibitors were added to tap water at a dosage of 1.0% of the tap water mass. The solubility rate of the long-acting, slow-release, controllable scale inhibitors was tested under different temperatures and dissolution times. The scale inhibition performance of the filtrate against CaCO3 and CaSO4 scale was tested. The densities of different scale inhibitors were also tested. The test results are shown in Table 1. Figure 1-4 .

[0066] Table 1. Test data on the slow-release, scale inhibition performance, and density of various long-acting controlled-release scale inhibitors.

[0067]

[0068]

[0069] As can be seen from Examples 1-3, by changing the type of slow-release carrier while keeping other components constant, scale inhibitors suitable for different temperature ranges can be prepared to meet various on-site construction requirements. Furthermore, by further optimizing the raw material formulation, scale inhibitors suitable for higher temperatures, as described in Example 4, can also be prepared. At different dissolution temperatures, the effective action time of the long-acting slow-release controllable scale inhibitors in each example is over 90 days, and can even be as long as 150 days. Within the effective period, the scale inhibition rate is consistently above 80.0%, and the scale inhibition performance is maintained even after three months of use, effectively extending the protection time for the wellbore. Comparative Example 1 shows that without the addition of a synergist, the scale inhibition rate of the long-acting slow-release controllable scale inhibitor is significantly reduced, and the scale inhibition time is shortened. Comparative Examples 2 and 3 show that when using a single perfluoroalkyl sulfonate or maleic acid-acrylic acid copolymer as a synergist, the compatibility between the slow-release carrier and the scale inhibitor is poor, making it impossible to process and prepare scale inhibitor particles. Therefore, it does not possess long-acting slow-release performance. The reasons for this are still under further investigation. This invention utilizes a composite system of perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer. On one hand, it improves the interfacial compatibility between the carrier and the scale inhibitor (organophosphorus) during the processing and modification of polymer materials. On the other hand, after dissolution, the polar groups of the perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer exhibit scale inhibition effects on calcium ions and also have a synergistic effect. Therefore, the use of the perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer composite system can significantly improve the scale inhibition rate of long-acting slow-release controllable scale inhibitors.

[0070] The application process of the long-acting, slow-release, controllable scale inhibitor involves calculating the dosage of the solid granular long-acting, slow-release, controllable scale inhibitor based on the oil well fluid volume, dosage concentration, and shelf life. The calculation formula is as follows: Dosage = Fluid Volume (m³ / s) 3 × Dosage concentration (80~120mg / L) × Shelf life (90d) / 60% (effective drug content).

[0071] Laboratory simulation and field application tests of a long-acting, slow-release, controllable scale inhibitor were conducted in a specific oil reservoir. The well's production rate was 2.05 m³ / s. 3 The well produces 1.40 t / d of oil with a water cut of 31.7%. The produced fluid has a pH of 6-8, a salinity of 50,000 ppm, and a total alkalinity >500 mg / L. Severe scaling in the well leads to frequent pump inspections due to scale buildup. Laboratory simulations were conducted using field water samples to dissolve the scale inhibitor from Example 2. The solubility rate of the scale inhibitor and the measured scale inhibition rates of CaCO3 and CaSO4 are shown in Table 2.

[0072] Table 2 shows the test data of scale inhibitor slow release and scale inhibition performance in Example 2, using on-site water sample dissolution.

[0073]

[0074] In 2024, the long-acting, slow-release, controllable scale inhibitor prepared in Example 2 was applied to two oil wells in the field. The average dosage was 200 kg / application, with an application cycle of 120 days. The test wells operated normally, and no scaling or pump jamming occurred. The free calcium ion content in the produced fluid increased from 3850.00 mg / L before application to 4685.00 mg / L. 2+ With a content increase of >20.0%, the long-acting, slow-release, controllable scale inhibitor demonstrated significant scale inhibition effects. During the trial, the two oil wells required 5 fewer well workover operations, saving approximately 80,000 yuan in construction and tubing rod costs, while also reducing production losses by approximately 30,000 yuan. After deducting the cost difference between the long-acting, slow-release, controllable scale inhibitor and the liquid scale inhibitor, the total comprehensive economic benefit was approximately 40,000 yuan.

[0075] In summary, the long-acting, slow-release, controllable scale inhibitor of this invention achieves synergistic and slow-release effects during the dissolution and slow-release process by uniformly dispersing and coating the scale inhibitor with a slow-release carrier. It releases the active ingredient slowly at a stable rate, thus continuously and efficiently inhibiting scale formation, significantly reducing the frequency of scale inhibitor addition and lowering operating costs. Furthermore, by using different types of slow-release carriers, the solubility of the scale inhibitor at different temperatures can be adjusted to obtain a scale inhibitor suitable for various temperature environments, meeting diverse on-site construction requirements. Simultaneously, this scale inhibitor exhibits excellent scale inhibition performance under complex water quality conditions, especially in harsh environments with high hardness and high alkalinity, effectively inhibiting the formation and deposition of scale.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A long-acting, slow-release, controllable scale inhibitor for oilfield use, characterized in that, Long-acting, slow-release, controllable scale inhibitor formulated from the following components by weight percentage: Organophosphorus 5.0~40.0%, sustained-release carrier 40.0~80.0%, filler 5.0~25.0%, synergist 1.0~5.0%, plasticizer 1.0~5.0%, total 100%; The organophosphorus is selected from at least one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediaminetetramethylidene phosphonic acid, and disodium hydroxyethylidene diphosphonate; The sustained-release carrier is selected from three of the following: polyacrylic acid, polymaleic anhydride, polybutylene terephthalate, polyurethane, polyamide, and polylactic acid, and used in combination. The filler is any one of the following: porous molecular sieve modified with silane coupling agent, diatomaceous earth, and porous polymer microspheres; The synergist is a composite system of perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer; The plasticizer is at least one of glycerol, triethylene glycol, and N-methylpyrrolidine; The preparation method of the scale inhibitor is as follows: First, the organophosphorus compound, slow-release carrier, filler, synergist and plasticizer are mixed and stirred evenly. Then, the mixture is added to a twin-screw extruder for melt plasticizing and extrusion, cooling, granulation and screening to obtain long-acting slow-release controllable scale inhibitor particles. The temperature of the twin-screw extruder is 40-60℃ in the feed section, 120-180℃ in the melting section, 140-200℃ in the compression section and 180-220℃ in the metering section. The melt plasticizing time is 2-6 min.

2. The long-acting, slow-release, controllable scale inhibitor for oilfield use as described in claim 1, characterized in that, The long-acting, slow-release, controllable scale inhibitor particles have a particle size of 1-2 mm and a density of 1.30-1.50 g / cm³. 3 .

3. The long-acting, slow-release, controllable scale inhibitor for oilfield use as described in claim 1, characterized in that, The synergist is a composite system of perfluoroalkyl sulfonate and maleic acid-acrylic acid copolymer in a mass ratio of 1:2 to 2:

1.

4. The long-acting, slow-release, controllable scale inhibitor for oilfield use as described in claim 1, characterized in that, The long-acting, slow-release, controllable scale inhibitor has a scale inhibition rate of ≥80.0% for calcium sulfate and calcium carbonate.

5. The application of a long-acting, slow-release, controllable scale inhibitor for oilfield use as described in any one of claims 1-4, characterized in that, Suitable for reservoir temperatures of 30℃~150℃.

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