Composite scale inhibiting and removing agent for acid producing thermophilic bacteria in geothermal well and preparation method thereof

Abstract

The present application relates to the technical field of descaling, and discloses a heat-producing acidophilic bacteria geothermal well scale-preventing and descaling composite agent and a preparation method thereof, comprising the following components: heat-producing acidophilic bacteria agent, maleic anhydride grafted modified polyaspartic acid, organic phosphonate, silicon dispersant, corrosion inhibitor, stabilizer, temperature adaptive composite additive, and deionized water; the composite agent has excellent comprehensive performance, is environmentally friendly, practical, and has a long service life, and the overall technical scheme is scientific and reasonable and has strong practicality. Compared with existing chemical agents, the present application introduces a microbial component, reduces the amount of chemical agents, is more environmentally friendly, and the microbial metabolites can be naturally degraded and will not cause secondary pollution; compared with existing microbial agents, the present application solves the problem of high-temperature inactivation of the strain through component synergy, and improves the long-acting property of the agent.

Description

Technical Field

[0001] This invention relates to the field of descaling technology, specifically to a composite agent for preventing and removing scale in geothermal wells containing thermophilic acid-producing bacteria and its preparation method. Background Technology

[0002] With the large-scale development and utilization of geothermal resources, geothermal wells, during long-term operation, readily undergo chemical reactions to form deposits such as calcium carbonate and magnesium scale due to the high concentration of calcium, magnesium ions, and bicarbonate in the produced water under high temperature and pressure conditions. These scale deposits adhere to the walls of geothermal well pipes, oil pipelines, and related equipment, leading to a reduction in pipe diameter and increased flow resistance. This not only reduces the heat exchange efficiency and water output of the geothermal well but also accelerates pipe corrosion, shortens equipment lifespan, and increases maintenance costs and safety hazards in geothermal development. Therefore, scale prevention and removal have become crucial for the long-term stable operation of geothermal wells.

[0003] Currently, the scale inhibitors and descaling agents commonly used in geothermal wells are mainly divided into chemical agents, including organophosphonates and polycarboxylic acid polymers. These agents achieve scale inhibitor and descaling effects through chelation and dispersion. However, under the high-temperature conditions of geothermal wells above 100°C, they are prone to decomposition and failure, resulting in a significant decrease in the activity retention rate. Furthermore, long-term use can cause certain environmental pollution. At the same time, their corrosion inhibition performance is limited, making it difficult to meet the dual needs of scale inhibitor and descaling as well as pipeline protection.

[0004] Therefore, developing a composite agent that can adapt to the high-temperature working conditions of geothermal wells, has excellent scale prevention and removal effects, high-temperature stability and corrosion inhibition performance, and is environmentally friendly, efficient and has a long service life has become an urgent technical problem to be solved in the field of geothermal development. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite agent for preventing and removing scale in geothermal wells containing thermophilic acid-producing bacteria, and its preparation method.

[0006] The specific technical solution is as follows: A composite agent for preventing and removing scale in geothermal wells containing thermophilic acid-producing bacteria, characterized in that it comprises the following components: 8-12 parts of thermophilic acid-producing bacteria agent, 6-10 parts of maleic anhydride-grafted modified polyaspartic acid, 4-6 parts of organophosphonate, 3-5 parts of silicon dispersant, 2-4 parts of corrosion inhibitor, 1-3 parts of stabilizer, 0.5-1.5 parts of temperature-adaptive composite additive, and 50-70 parts of deionized water;

[0007] The thermophilic acid-producing bacteria is *Bacillus stearothermophilus*, with a bacterial concentration of 10. 8 -10 9 CFU / mL.

[0008] As a further technical solution, the preparation method of the maleic anhydride grafted modified polyaspartic acid includes the following steps:

[0009] (1) Take polyaspartic acid and maleic anhydride in a mass ratio of 10:3-5 and add them to the reaction vessel. Add 2-3 times the mass of polyaspartic acid in deionized water, stir to dissolve, and adjust the pH to 3.0-4.0 with dilute sulfuric acid.

[0010] (2) Heat to 80-90℃ and add 0.5%-1.0% of polyaspartic acid by mass of a composite initiator, wherein the composite initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 4:1, and react at a constant temperature for 3-4 hours;

[0011] (3) After the reaction is complete, adjust the pH to 7.0-7.5 with sodium hydroxide solution, remove excess water by vacuum distillation, dry under vacuum at 80-90℃ for 2-3 hours, and pulverize to 80-100 mesh to obtain modified polyaspartic acid powder.

[0012] Vacuum distillation is carried out at a pressure of 0.06-0.08 MPa and a temperature of 60-70℃.

[0013] As a further technical solution, the temperature-adaptive composite additive is a mixture of polyethylene glycol 2000 and pentaerythritol in a mass ratio of 3:1.

[0014] As a further technical solution, the organophosphonate is a mixture of hydroxyethylidene diphosphonate and aminotrimethylene phosphonate in a mass ratio of 2:1. The organophosphonate needs to be modified by ultrasound before use. The ultrasound power is 200-300W, the ultrasound frequency is 40kHz, and the ultrasound time is 15-20min. After ultrasound, it is cooled to room temperature for later use.

[0015] As a further technical solution, the silicon dispersant is methyl methacrylate grafted modified polyether siloxane with a grafting rate of 8%-12% and a molecular weight of 1000-2000, and the silicon dispersant contains 0.1%-0.2% graphene micro flakes by mass.

[0016] As a further technical solution, the corrosion inhibitor is a mixture of benzotriazole, zinc sulfate and sodium molybdate in a mass ratio of 6:4:1.

[0017] As a further technical solution, the stabilizer is a mixture of sodium citrate, disodium EDTA, and sodium pyrophosphate in a mass ratio of 5:5:1.

[0018] The preparation method of the thermophilic acid-producing bacteria geothermal well scale prevention and removal composite agent includes the following steps:

[0019] S1. Take the amount of deionized water specified in the formula and add it to a sterile reactor. Heat the mixture to 40-50℃ and adjust the stirring speed to 150-200r / min. Add the amount of stabilizer specified in the formula and stir until dissolved. Keep the mixture warm for 10-15 minutes. Check the clarity of the mixture to ensure that there is no precipitation or turbidity.

[0020] S2. Add the prescribed amounts of ultrasonically modified organophosphonate, silica dispersant, and corrosion inhibitor to the reactor in sequence. After each component is added, continue stirring for 20-30 minutes at a stirring speed of 180-200 r / min to ensure that the components are completely dissolved and a mixture is obtained.

[0021] S3. Add the formulated amount of maleic anhydride-grafted modified polyaspartic acid and temperature-adaptive composite additive to the mixture, heat to 60-70℃ under nitrogen protection, adjust the stirring speed to 250-300r / min, stir for 30-40min, so that each component is evenly dispersed in the mixture.

[0022] S4. Cool to 35-45℃, add the prescribed amount of thermophilic acid-producing bacteria agent, stir at low speed for 15-20 minutes (stirring speed is 80-100 r / min), and introduce sterile air into the reaction vessel during stirring at a flow rate of 0.3-0.5 L / min to obtain the crude compound agent.

[0023] S5. Filter the crude compound reagent with a filtration accuracy of 0.22μm and a filtration pressure of 0.1-0.15MPa to remove impurities and undissolved microparticles.

[0024] S6. Purge the filtered composite reagent with nitrogen gas for 3-5 minutes at a flow rate of 0.5-1.0 L / min to remove dissolved oxygen from the reagent;

[0025] S7. Detect the pH value of the agent, control the pH to 4.5-5.0, and dispense the finished compound agent under sterile conditions.

[0026] As a further technical solution, in step S1, the sterile reactor needs to be sterilized at high temperature before use, with a sterilization temperature of 121°C and a sterilization time of 30 minutes, and then cooled to room temperature before use.

[0027] As a further technical solution, in step S4, the sterile air needs to be filtered through a 0.22μm filter membrane to ensure that no bacteria are mixed in.

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

[0029] This invention, through rational optimization of each component and specific preparation process, synergistically enhances the performance of the composite agent, effectively solving the problems of high-temperature inactivation, poor efficacy, and difficulty in simultaneously addressing corrosion inhibition requirements in existing geothermal well anti-scaling and descaling agents. By introducing a thermophilic acid-producing bacterium agent made from *Bacillus stearothermophilus*, this strain can adapt to the high-temperature conditions of geothermal wells, continuously producing acid under high-temperature environments to lower the system's pH value and disrupt the thermodynamic conditions for the formation of calcium carbonate and magnesium scale. Simultaneously, its metabolites can chemically react with the scale, promoting scale dissolution, thereby achieving highly efficient anti-scaling and descaling effects. This solves the problems of high-temperature inactivation and insufficient anti-scaling and descaling efficiency in existing microbial agents. Compared to ambient-temperature strains, the high-temperature tolerance of *Bacillus stearothermophilus* allows it to maintain high activity even under extreme geothermal well conditions, extending the effective action time of the agent.

[0030] This invention further enhances the overall performance of the agent through the synergistic effect of its components. Maleic anhydride-grafted modified polyaspartic acid, prepared using a specific process, possesses stronger chelating ability, forming stable chelates with calcium and magnesium ions in water to prevent scale formation. Simultaneously, it synergistically enhances the scale prevention and removal effect with organophosphonates. The organophosphonates, after ultrasonic modification, exhibit better dispersibility and effectively inhibit scale aggregation. The addition of graphene microflakes to the silicon dispersant improves dispersibility and prevents existing microscale from adhering to the pipe surface. Combined with chelating components, it achieves dual scale prevention and inhibition. The corrosion inhibitor utilizes a complex of benzotriazole, zinc sulfate, and sodium molybdate. The appropriate formulation can form a preliminary protective film on the surface of N80 steel pipes. The metabolites of thermophilic acid-producing bacteria can work synergistically with the corrosion inhibitor to enhance the density of the protective film, prevent the corrosive medium from contacting the pipe, and thus improve the corrosion inhibition effect. This solves the problems of insufficient corrosion inhibition performance and easy corrosion of pipes caused by existing agents. The temperature-adaptive composite additive can prevent the agent from decomposing and separating at high temperatures, improve the retention rate of active components, and promote the synergistic effect of each component. The stabilizer further ensures the storage stability and consistency of use of the agent. The components work together to ensure that the agent can maintain excellent performance under high-temperature conditions.

[0031] The composite agent of this invention not only possesses excellent comprehensive performance but also boasts advantages such as environmental friendliness, practicality, and long service life. The overall technical solution is scientifically sound and highly practical. Compared to existing chemical agents, this invention introduces microbial components, reducing the amount of chemical agents used, making it more environmentally friendly. Furthermore, the microbial metabolites are biodegradable, preventing secondary pollution. Compared to existing microbial agents, this invention solves the problem of high-temperature inactivation of bacterial strains through component synergy, enhancing the long-term effectiveness of the agent. In summary, this invention effectively addresses many shortcomings of existing geothermal well anti-scaling and descaling agents, extending the service life of geothermal wells, reducing maintenance costs, and improving the economic efficiency and safety of geothermal resource development, thus possessing broad application prospects. Attached Figure Description

[0032] Figure 1 This is a flowchart of the preparation method of a composite agent for preventing and removing scale in geothermal wells containing thermophilic acid-producing bacteria. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention discloses a thermophilic acid-producing bacteria-based composite agent for preventing and removing scale in geothermal wells. By weight, it comprises the following components: 8-12 parts of thermophilic acid-producing bacteria, 6-10 parts of maleic anhydride-grafted modified polyaspartic acid, 4-6 parts of organophosphonate, 3-5 parts of silica dispersant, 2-4 parts of corrosion inhibitor, 1-3 parts of stabilizer, 0.5-1.5 parts of temperature-adaptive composite additive, and 50-70 parts of deionized water. These components work synergistically to achieve highly efficient scale prevention and removal in geothermal wells, while also possessing good corrosion inhibition properties and high-temperature stability, making it suitable for the extreme operating conditions of geothermal wells. The thermophilic acid-producing bacteria is *Bacillus stearothermophilus*, with a bacterial concentration controlled at 10... 8 -10 9 CFU / mL.

[0035] It should be noted that the raw materials used in the following examples and comparative examples are all commercially available products (unless otherwise specified).

[0036] Raw materials include:

[0037] 1. Thermophilic acid-producing bacteria inoculum: Bacillus stearothermophilus, bacterial concentration of 10. 8 -10 9 CFU / mL, adjust to the concentration required for the corresponding example as needed.

[0038] 2. Maleic anhydride grafting modification of polyaspartic acid: The specific steps are as follows:

[0039] (1) Take polyaspartic acid and maleic anhydride in the corresponding mass ratio and add them to the reaction vessel. Add 2-3 times the mass of polyaspartic acid in deionized water, stir to dissolve, and adjust the pH to 3.0-4.0 with dilute sulfuric acid.

[0040] (2) Heat to 80-90℃ and add 0.5%-1.0% of polyaspartic acid as a composite initiator. The composite initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 4:1. React at a constant temperature for 3-4 hours.

[0041] (3) After the reaction is completed, the pH is adjusted to 7.0-7.5 with sodium hydroxide solution, and excess water is removed by vacuum distillation. The pressure of vacuum distillation is controlled at 0.06-0.08 MPa and the temperature is controlled at 60-70℃. The product is then vacuum dried at 80-90℃ for 2-3 hours and pulverized to 80-100 mesh to obtain modified polyaspartic acid powder.

[0042] 3. Organophosphonates: Hydroxyethylidene diphosphonate and aminotrimethylene phosphonate are mixed in a mass ratio of 2:1. Before use, they are modified by ultrasound with an ultrasound power of 200-300W, an ultrasound frequency of 40kHz, and an ultrasound time of 15-20min. After ultrasound, they are cooled to room temperature for use.

[0043] 4. Silicon dispersant: Methyl methacrylate grafted modified polyether siloxane with a grafting rate of 8%-12% and a molecular weight of 1000-2000, and the silicon dispersant contains 0.1%-0.2% graphene micro flakes by mass.

[0044] 5. Corrosion inhibitor: Benzotriazole, zinc sulfate and sodium molybdate are mixed in a mass ratio of 6:4:1.

[0045] 6. Stabilizer: Sodium citrate, disodium EDTA, and sodium pyrophosphate are mixed in a mass ratio of 5:5:1.

[0046] 7. Temperature-adaptive composite additive: Polyethylene glycol 2000 and pentaerythritol are mixed at a mass ratio of 3:1.

[0047] 8. Deionized water: Conventional industrial-grade deionized water, free of impurities and odors.

[0048] The following are specific examples:

[0049] Example 1:

[0050] The thermophilic acid-producing bacteria geothermal well anti-scaling and descaling composite agent of this embodiment has the following components by weight: 8 parts thermophilic acid-producing bacteria agent, 6 parts maleic anhydride grafted modified polyaspartic acid, 4 parts organophosphonate, 3 parts silicon dispersant, 2 parts corrosion inhibitor, 1 part stabilizer, 0.5 parts temperature-adaptive composite additive, and 50 parts deionized water.

[0051] The specific parameters of each component are as follows: Bacillus stearothermophilus cell concentration 10 8In the preparation of maleic anhydride-grafted modified polyaspartic acid (CFU / mL), the mass ratio of polyaspartic acid to maleic anhydride was 10:3, the amount of deionized water added was twice the mass of polyaspartic acid, the pH was adjusted to 3.0, the temperature was raised to 80℃, the amount of composite initiator added was 0.5% of the mass of polyaspartic acid, the reaction was carried out at a constant temperature for 3 hours, the pressure was reduced by 0.06 MPa and the temperature was 60℃, the vacuum drying temperature was 80℃ and the time was 2 hours, and the powder was pulverized to 80 mesh; the ultrasonic modification of organophosphonate was carried out at a power of 200W and a time of 15 minutes; the grafting rate of silicon dispersant was 8% and the molecular weight was 1000, and the amount of graphene microplates added was 0.1%.

[0052] The specific steps of the compound drug preparation method in this embodiment are as follows:

[0053] S1. The sterile reactor is sterilized at high temperature (121℃) for 30 minutes before use. After cooling to room temperature, it is ready for use. Take 50 parts of deionized water and add it to the sterile reactor. Heat the reactor to 40℃ and adjust the stirring speed to 150 r / min. Add 1 part of stabilizer and stir to dissolve. Keep the mixture warm for 10 minutes and check the clarity of the mixture to ensure that there is no sediment or turbidity.

[0054] S2. Add 4 parts of ultrasonically modified organophosphonate, 3 parts of silica dispersant, and 2 parts of corrosion inhibitor to the reactor in sequence. After each component is added, continue stirring for 20 minutes at a stirring speed of 180 r / min to ensure that the components are completely dissolved and a mixture is obtained.

[0055] S3. Add 6 parts of maleic anhydride-grafted modified polyaspartic acid and 0.5 parts of temperature-adaptive composite additive to the mixture, heat to 60°C under nitrogen protection, adjust the stirring speed to 250 r / min, and stir for 30 min to ensure that the components are evenly dispersed in the mixture.

[0056] S4. Cool down to 35℃, add 8 parts of thermophilic acid-producing bacteria agent, stir at low speed for 15 minutes at a stirring speed of 80 r / min, and introduce sterile air into the reaction vessel during the stirring process. The sterile air is filtered through a 0.22 μm filter membrane to ensure that no contaminants are mixed in, and the flow rate is 0.3 L / min to obtain the crude compound agent.

[0057] S5. Filter the crude compound reagent with a filtration accuracy of 0.22μm and a filtration pressure of 0.1MPa to remove impurities and undissolved microparticles.

[0058] S6. Purge the filtered composite reagent with nitrogen gas for 3 minutes at a flow rate of 0.5 L / min to remove dissolved oxygen from the reagent.

[0059] S7. Detect the pH value of the agent, control the pH to 4.5, and dispense the finished compound agent under sterile conditions.

[0060] Example 2:

[0061] The thermophilic acid-producing bacteria geothermal well scale prevention and removal composite agent of this embodiment has the following components by weight: 12 parts thermophilic acid-producing bacteria agent, 10 parts maleic anhydride grafted modified polyaspartic acid, 6 parts organophosphonate, 5 parts silicon dispersant, 4 parts corrosion inhibitor, 3 parts stabilizer, 1.5 parts temperature-adaptive composite additive, and 70 parts deionized water.

[0062] The specific parameters of each component are as follows: Bacillus stearothermophilus cell concentration 10 9 In the preparation of maleic anhydride-grafted modified polyaspartic acid, the mass ratio of polyaspartic acid to maleic anhydride was 10:5, the amount of deionized water added was 3 times the mass of polyaspartic acid, the pH was adjusted to 4.0, the temperature was raised to 90℃, the amount of composite initiator added was 1.0% of the mass of polyaspartic acid, the reaction was carried out at a constant temperature for 4 hours, the pressure was reduced by 0.08 MPa and the temperature was 70℃, the temperature was reduced by 90℃ and the time was 3 hours, and the powder was pulverized to 100 mesh; the ultrasonic modification of organophosphonate was carried out at a power of 300W and a time of 20 minutes; the grafting rate of silicon dispersant was 12% and the molecular weight was 2000, and the amount of graphene microplates added was 0.2%.

[0063] The specific steps of the compound drug preparation method in this embodiment are as follows:

[0064] S1. The sterile reactor is sterilized at high temperature (121℃) for 30 minutes before use. After cooling to room temperature, it is ready for use. Take 70 parts of deionized water and add it to the sterile reactor. Heat the reactor to 50℃ and adjust the stirring speed to 200 r / min. Add 3 parts of stabilizer and stir to dissolve. Keep the mixture warm for 15 minutes and check the clarity of the mixture to ensure that there is no sediment or turbidity.

[0065] S2. Add 6 parts of ultrasonically modified organophosphonate, 5 parts of silica dispersant, and 4 parts of corrosion inhibitor to the reactor in sequence. After each component is added, continue stirring for 30 minutes at a stirring speed of 200 r / min to ensure that the components are completely dissolved and obtain a mixture.

[0066] S3. Add 10 parts of maleic anhydride-grafted modified polyaspartic acid and 1.5 parts of temperature-adaptive composite additive to the mixture, heat to 70°C under nitrogen protection, adjust the stirring speed to 300 r / min, and stir for 40 min to ensure that the components are evenly dispersed in the mixture.

[0067] S4. Cool down to 45℃, add 12 parts of thermophilic acid-producing bacteria agent, stir at low speed for 20 minutes at a stirring speed of 100 r / min, and introduce sterile air into the reaction vessel during the stirring process. The sterile air is filtered through a 0.22 μm filter membrane to ensure that no contaminants are mixed in, and the flow rate is 0.5 L / min to obtain the crude compound agent.

[0068] S5. Filter the crude compound reagent with a filtration accuracy of 0.22μm and a filtration pressure of 0.15MPa to remove impurities and undissolved microparticles.

[0069] S6. Purge the filtered composite reagent with nitrogen gas for 5 minutes at a flow rate of 1.0 L / min to remove dissolved oxygen from the reagent.

[0070] S7. Detect the pH value of the agent, control the pH to 5.0, and dispense the finished compound agent under aseptic conditions.

[0071] Example 3:

[0072] The thermophilic acid-producing bacteria geothermal well scale prevention and removal composite agent of this embodiment has the following components by weight: 10 parts thermophilic acid-producing bacteria agent, 8 parts maleic anhydride grafted modified polyaspartic acid, 5 parts organophosphonate, 4 parts silicon dispersant, 3 parts corrosion inhibitor, 2 parts stabilizer, 1.0 part temperature-adaptive composite additive, and 60 parts deionized water.

[0073] The specific parameters of each component are as follows: Bacillus stearothermophilus cell concentration 5×10 8 In the preparation of maleic anhydride-grafted modified polyaspartic acid (CFU / mL), the mass ratio of polyaspartic acid to maleic anhydride was 10:4, the amount of deionized water added was 2.5 times the mass of polyaspartic acid, the pH was adjusted to 3.5, the temperature was raised to 85℃, the amount of composite initiator added was 0.75% of the mass of polyaspartic acid, the reaction was carried out at a constant temperature for 3.5 h, the pressure of vacuum distillation was 0.07 MPa and the temperature was 65℃, the vacuum drying temperature was 85℃ and the time was 2.5 h, and the powder was pulverized to 90 mesh; the ultrasonic modification of organophosphonate was carried out with a power of 250 W and a time of 17.5 min; the grafting rate of silicon dispersant was 10% and the molecular weight was 1500, and the amount of graphene microplates added was 0.15%.

[0074] The specific steps of the compound drug preparation method in this embodiment are as follows:

[0075] S1. The sterile reactor is sterilized at high temperature (121℃) for 30 minutes before use. After cooling to room temperature, it is ready for use. Take 60 parts of deionized water and add it to the sterile reactor. Heat the reactor to 45℃ and adjust the stirring speed to 175 r / min. Add 2 parts of stabilizer and stir to dissolve. Keep the mixture warm for 12.5 minutes and check the clarity of the mixture to ensure that there is no sediment or turbidity.

[0076] S2. Add 5 parts of ultrasonically modified organophosphonate, 4 parts of silica dispersant, and 3 parts of corrosion inhibitor to the reactor in sequence. After each component is added, continue stirring for 25 minutes at a stirring speed of 190 r / min to ensure that the components are completely dissolved and obtain a mixture.

[0077] S3. Add 8 parts of maleic anhydride-grafted modified polyaspartic acid and 1.0 part of temperature-adaptive composite additive to the mixture, heat to 65°C under nitrogen protection, adjust the stirring speed to 275 r / min, and stir for 35 min to ensure that the components are evenly dispersed in the mixture.

[0078] S4. Cool down to 40℃, add 10 parts of thermophilic acid-producing bacteria agent, stir at low speed for 17.5 min, stirring speed is 90 r / min, during the stirring process, sterile air is introduced into the reaction vessel, sterile air is filtered through a 0.22μm filter membrane to ensure no contamination of bacteria, flow rate is 0.4L / min, to obtain crude compound agent.

[0079] S5. Filter the crude compound reagent with a filtration accuracy of 0.22μm and a filtration pressure of 0.125MPa to remove impurities and undissolved microparticles.

[0080] S6. Purge the filtered composite reagent with nitrogen gas for 4 minutes at a flow rate of 0.75 L / min to remove dissolved oxygen from the reagent.

[0081] S7. Detect the pH value of the agent, control the pH to 4.75, and dispense the finished compound agent under sterile conditions.

[0082] Comparative Example 1:

[0083] The scale inhibitor and descaling agent in this comparative example has the following components by weight: 8 parts polyaspartic acid, 5 parts organophosphonate, 4 parts silicon dispersant, 3 parts corrosion inhibitor, 2 parts stabilizer, 1.0 part temperature-adaptive composite additive, and 60 parts deionized water.

[0084] The specific parameters and preparation methods of each component are completely consistent with those in Example 3.

[0085] Comparative Example 2:

[0086] The scale inhibitor and descaling agent of this comparative example has the following components by weight: 10 parts thermophilic acid-producing bacteria agent, 8 parts maleic anhydride-grafted modified polyaspartic acid, 5 parts organophosphonate, 4 parts silicon dispersant, 3 parts corrosion inhibitor, 2 parts stabilizer, and 60 parts deionized water.

[0087] The specific parameters and preparation methods of each component are completely consistent with those in Example 3.

[0088] test:

[0089] Experiment 1: Scale prevention and removal performance test;

[0090] The scale prevention and removal rates of the agents in Examples 1-3 and Comparative Examples 1-2 were tested under simulated geothermal well conditions to verify the effects of thermophilic acid-producing bacteria, maleic anhydride-grafted modified polyaspartic acid, and temperature-adaptive composite additives on the scale prevention and removal performance of the agents. The scale prevention rate mainly reflects the preventive effect of the agents, and the scale removal rate mainly reflects the removal effect of the agents. Both are the core performance indicators of scale prevention and removal agents for geothermal wells.

[0091] The water quality composition of simulated geothermal well produced water (calcium hardness 800 mg / L, magnesium hardness 300 mg / L, bicarbonate concentration 1200 mg / L, pH 7.8-8.2) was analyzed under high temperature and high pressure conditions (simulating geothermal well operating conditions: temperature 120℃, pressure 1.5 MPa). The test reagent was added and reacted at constant temperature and pressure for a certain period of time. The scale prevention rate was calculated by weighing the scale sample. At the same time, a standard scale sample generated under the same operating conditions was immersed in the test reagent, and the scale removal rate was calculated to directly reflect the scale prevention and removal capabilities of the reagent.

[0092] Experimental instruments: high temperature and high pressure reactor, electronic balance (accuracy 0.001g), forced air drying oven, pH meter, constant temperature water bath, filtration device;

[0093] Test reagents: calcium chloride, magnesium chloride, sodium bicarbonate (all analytical grade), finished reagents of Examples 1-3 and Comparative Examples 1-2, and deionized water.

[0094] (1) Anti-scaling rate test:

[0095] ①Preparation of simulated geothermal well produced water: Weigh a certain amount of calcium chloride, magnesium chloride, and sodium bicarbonate, add deionized water, stir to dissolve, adjust the pH to 8.0, and obtain a simulated water sample with calcium hardness of 800 mg / L, magnesium hardness of 300 mg / L, and bicarbonate concentration of 1200 mg / L. Dispense the sample into 5 identical high-temperature and high-pressure reactors, and add 1000 mL of the simulated water sample to each reactor.

[0096] ② The reagents of Examples 1-3 and Comparative Examples 1-2 were added to 5 reaction vessels respectively. The reagent dosage was 50 mg / L (the dosage of reagents for conventional geothermal wells). At the same time, a blank control group was set up (no reagents were added, and all other conditions were the same).

[0097] ③ Close the reactor, raise the temperature to 120℃, adjust the pressure to 1.5MPa, and keep the reaction at constant temperature and pressure for 24 hours. After the reaction is completed, let it cool naturally to room temperature, filter all the solution in the reactor, and collect the filter residue (scale).

[0098] ④ Place the scale sample in a forced-air drying oven and dry it at 105℃ until constant weight. Weigh the scale sample using an electronic balance and record the data.

[0099] ⑤ Calculate the scale prevention rate: Scale prevention rate = (scale mass of blank control group - scale mass of sample group) / scale mass of blank control group × 100%. Each sample is tested in parallel 3 times, and the average value is taken as the final scale prevention rate.

[0100] (2) Descaling rate test:

[0101] ① Preparation of standard scale samples: Using the above-mentioned simulated geothermal well produced water, the mixture of calcium carbonate and magnesium scale was reacted in a high-temperature and high-pressure reactor (120℃, 1.5MPa) for 48 hours to generate a mixture of calcium carbonate and magnesium scale. The mixture was filtered and dried to constant weight to obtain standard scale samples. The mass of each scale sample was controlled at about 2.000g.

[0102] ② Take the reagents from Examples 1-3 and Comparative Examples 1-2 respectively, prepare a reagent solution with a concentration of 50 mg / L, and dispense it into 5 identical beakers, adding 1000 mL of reagent solution to each beaker;

[0103] ③ Place the standard scale samples into 5 beakers respectively, put them in a constant temperature water bath, control the temperature at 120℃, and soak for 24 hours. Stir once every 6 hours during this period, and stir for 10 minutes each time.

[0104] ④ After soaking, remove the remaining scale sample, rinse it with deionized water, put it in a forced-air drying oven, dry it at 105℃ to constant weight, weigh the remaining scale sample with an electronic balance, and record the data;

[0105] ⑤ Calculate the descaling rate: Descaling rate = (Initial mass of standard scale sample - Mass of remaining scale sample) / Initial mass of standard scale sample × 100%. Each sample was tested in parallel 3 times, and the average value was taken as the final descaling rate. The results are as follows:

[0106] Table 1

[0107] Sample number Mass of scale in blank control group (g) Mass of scale in sample group (g) Anti-scaling rate (%) Initial mass (g) of standard scale sample Residual scale mass (g) Descaling rate (%) Example 1 1.862 0.172 90.8 2.003 0.210 89.5 Example 2 1.862 0.102 94.5 2.001 0.120 94.0 Example 3 1.862 0.129 93.1 2.002 0.148 92.6 Comparative Example 1 1.862 0.874 53.1 2.000 0.986 50.7 Comparative Example 2 1.862 0.428 76.9 2.004 0.481 76.0

[0108] As can be seen from the data of Experiment 1, the composite agents of Examples 1-3 all exhibited excellent scale prevention and removal performance, with scale prevention rates all above 90% and scale removal rates all above 89%, indicating that the composite agents of the present invention can achieve good scale prevention and removal effects within the range of various parameter values.

[0109] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A scale inhibition and removal composite agent for acid-producing thermophilic bacteria in geothermal wells, characterized in that, By weight, it includes the following components: 8-12 parts of thermophilic acid-producing bacteria agent, 6-10 parts of maleic anhydride-grafted modified polyaspartic acid, 4-6 parts of organophosphonate, 3-5 parts of silicon dispersant, 2-4 parts of corrosion inhibitor, 1-3 parts of stabilizer, 0.5-1.5 parts of temperature-adaptive composite additive, and 50-70 parts of deionized water; The thermophilic acid-producing bacteria is Bacillus stearothermophilus, the bacterial concentration is 10 8 -10 9 CFU / mL; The preparation method of the maleic anhydride grafted modified polyaspartic acid includes the following steps: (1) Take polyaspartic acid and maleic anhydride in a mass ratio of 10:3-5 and add them to the reaction vessel. Add 2-3 times the mass of polyaspartic acid in deionized water, stir to dissolve, and adjust the pH to 3.0-4.0 with dilute sulfuric acid. (2) Heat to 80-90℃ and add 0.5%-1.0% of polyaspartic acid by mass of a composite initiator, wherein the composite initiator is a mixture of ammonium persulfate and sodium bisulfite in a mass ratio of 4:1, and react at a constant temperature for 3-4 hours; (3) After the reaction is complete, adjust the pH to 7.0-7.5 with sodium hydroxide solution, remove excess water by vacuum distillation, dry under vacuum at 80-90℃ for 2-3 hours, and pulverize to 80-100 mesh to obtain modified polyaspartic acid powder. Vacuum distillation is carried out at a pressure of 0.06-0.08 MPa and a temperature of 60-70℃. The temperature-adaptive composite additive is a mixture of polyethylene glycol 2000 and pentaerythritol in a mass ratio of 3:

1. The silicon dispersant is methyl methacrylate grafted modified polyether siloxane with a grafting rate of 8%-12% and a molecular weight of 1000-2000, and contains 0.1%-0.2% graphene micro flakes by mass.

2. The combination agent according to claim 1, characterized by The organophosphonate is a mixture of hydroxyethylidene diphosphonate and aminotrimethylene phosphonate in a mass ratio of 2:

1. The organophosphonate needs to be modified by ultrasound before use. The ultrasound power is 200-300W, the ultrasound frequency is 40kHz, and the ultrasound time is 15-20min. After ultrasound, it should be cooled to room temperature for use.

3. The combination agent according to claim 1, wherein The corrosion inhibitor is a mixture of benzotriazole, zinc sulfate and sodium molybdate in a mass ratio of 6:4:

1.

4. The combination agent according to claim 1, wherein The stabilizer is a mixture of sodium citrate, disodium EDTA, and sodium pyrophosphate in a mass ratio of 5:5:

1.

5. The preparation method of the scale inhibition and removal composite agent of the acid producing thermophilic bacteria for geothermal well according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Take the amount of deionized water specified in the formula and add it to a sterile reactor. Heat the mixture to 40-50℃ and adjust the stirring speed to 150-200r / min. Add the amount of stabilizer specified in the formula and stir until dissolved. Keep the mixture warm for 10-15 minutes. Check the clarity of the mixture to ensure that there is no precipitation or turbidity. S2. Add the prescribed amounts of ultrasonically modified organophosphonate, silica dispersant, and corrosion inhibitor to the reactor in sequence. After each component is added, continue stirring for 20-30 minutes at a stirring speed of 180-200 r / min to ensure that the components are completely dissolved and a mixture is obtained. S3. Add the formulated amount of maleic anhydride-grafted modified polyaspartic acid and temperature-adaptive composite additive to the mixture, heat to 60-70℃ under nitrogen protection, adjust the stirring speed to 250-300r / min, stir for 30-40min, so that each component is evenly dispersed in the mixture. S4. Cool to 35-45℃, add the prescribed amount of thermophilic acid-producing bacteria agent, stir at low speed for 15-20 minutes (stirring speed is 80-100 r / min), and introduce sterile air into the reaction vessel during stirring at a flow rate of 0.3-0.5 L / min to obtain the crude compound agent. S5. Filter the crude compound reagent with a filtration accuracy of 0.22μm and a filtration pressure of 0.1-0.15MPa to remove impurities and undissolved microparticles. S6. Purge the filtered composite reagent with nitrogen gas for 3-5 minutes at a flow rate of 0.5-1.0 L / min to remove dissolved oxygen from the reagent; S7. Detect the pH value of the agent, control the pH to 4.5-5.0, and dispense the finished compound agent under sterile conditions.

6. The production method according to claim 5, characterized by, In step S1, the sterile reactor must be sterilized at high temperature before use. The sterilization temperature is 121°C and the sterilization time is 30 minutes. After cooling to room temperature, it can be used for future purposes.

7. The preparation method according to claim 5, characterized in that, In step S4, the sterile air needs to be filtered through a 0.22μm filter membrane to ensure that no bacteria are mixed in.

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