Polyamine shale inhibitor and preparation method thereof

Abstract

The invention discloses a polyamine shale inhibitor and a preparation method thereof, and belongs to the technical field of petroleum drilling fluid additives, the polyamine shale inhibitor is prepared from the following raw materials in parts by mass: 100 parts of ethidene diamine, 180 parts of epoxy chloropropane, 50 parts of 4-aminophenylboronic acid, 12-15 parts of aminated graphene quantum dot powder, 30 parts of concentrated sulfuric acid and 20 parts of trimethyl phosphate. According to the invention, through ternary coupling of 4-APBA / GQDs / supercritical process, the technical bottlenecks of insufficient rigidity and modification staticization of traditional polyamine are broken through. Meanwhile, a gradient sulfonation-phosphorylation modification process is developed, spatial gradient distribution of anion groups is achieved, and the industrial problem that the desorption rate of the inhibitor is high in the high-salt environment is solved. According to the invention, through molecular structure innovation and process innovation, the problem of shale inhibition in a high-temperature / high-salt / acidic composite stratum is successfully solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil drilling fluid additives, and particularly relates to a polyamine shale inhibitor and a preparation method thereof. Background Art

[0002] The development of deep shale oil and gas faces extreme working conditions (such as geothermal gradient > 4℃ / 100m, formation water salinity > 30%). Due to problems such as thermodynamic instability of the molecular structure and charge shielding effect of traditional polyamine inhibitors, the inhibition performance drops sharply under the combined conditions of high temperature / high salinity / acid, resulting in a significant increase in the accident rate of wellbore instability. In response, in the prior art, the salt resistance is usually improved by introducing sulfonic groups or quaternary ammonium groups, but there are the following bottlenecks: a. Insufficient molecular rigidity: The molecular chain segments move violently at high temperatures, resulting in the dissociation of the adsorption layer; b. Limitation of static modification: Traditional chemical bonds (such as covalent bonds and ionic bonds) cannot dynamically respond to changes in the formation environment; c. Defects in nano-dispersion: Physically blended nano-materials are prone to agglomeration and cannot achieve molecular-level dispersion.

[0003] At the same time, the development of deep shale formations requires that the inhibitor can still maintain a rolling recovery rate of > 90% under the conditions of 180℃ / 30% NaCl / pH = 3, while the rolling recovery rate of the prior art is less than 50% under this working condition. Therefore, it is urgent to break through the molecular design paradigm and develop innovative inhibitors with environmental self-adaptive ability. Summary of the Invention

[0004] The purpose of the present invention is to provide a polyamine shale inhibitor and a preparation method thereof to solve the problems of insufficient molecular rigidity, limitation of static modification, and nano-dispersion defects existing in traditional polyamine inhibitors.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A polyamine shale inhibitor, comprising the following raw materials in parts by mass: 100 parts of ethylenediamine, 180 parts of epichlorohydrin, 50 parts of 4-aminophenylboronic acid, 12 - 15 parts of amino-functionalized graphene quantum dot powder, 30 parts of concentrated sulfuric acid, and 20 parts of trimethyl phosphate.

[0006] Further, the particle size of the amino-functionalized graphene quantum dot powder is 2 - 3nm.

[0007] Further, the preparation method of the polyamine shale inhibitor comprises the following steps: Ethylenediamine, epichlorohydrin, 4-aminophenylboronic acid and amino-functionalized graphene quantum dot powder are added to a supercritical reactor, and then supercritical CO2 is introduced into it to construct a supercritical environment and carry out a dynamic polymerization reaction. After completion, the supercritical reactor is depressurized to atmospheric pressure, and concentrated sulfuric acid is slowly added dropwise thereto, controlling the dropping rate to be 4-5 mL / min, and stirring and reacting at 55-60 °C and atmospheric pressure for 2-4 hours. After completion, trimethyl phosphate is added to the supercritical reactor again, the temperature is raised to 80-85 °C, and the reaction is carried out for 2-2.5 hours under nitrogen protection. After the reaction is completed, the pH is adjusted to 6.5-7.0 with a 10% NaOH solution by mass fraction to obtain a reaction solution. After the reaction solution is subjected to dialysis and drying treatment, a polyamine shale inhibitor is obtained.

[0008] Further, the construction of the supercritical environment includes the following steps: Supercritical CO2 is introduced into the supercritical reactor until the pressure reaches 35-40 MPa, the magnetic stirring is started, and the temperature is raised to 80-90 °C at a rate of 1-5 °C / min, and the pressure is maintained at 35 MPa ± 0.5 MPa.

[0009] Further, the dynamic polymerization reaction includes the following steps: The reaction is continuously carried out at 80-90 °C and 35 MPa ± 0.5 MPa for 4-6 hours, and then the viscosity of the system is monitored by an online viscometer. When the viscosity reaches 5000 ± 500 mPa·s, the reaction end point is determined.

[0010] Further, the dialysis and drying treatment includes the following steps: The reaction solution is transferred to a dialysis bag and dialyzed in deionized water for 48 hours. The dialyzed reaction solution is dried to a constant weight in a vacuum drying oven at 60-80 °C.

[0011] Further, the mass fraction of the concentrated sulfuric acid is 98%.

[0012] Further, the cut-off molecular weight of the dialysis bag is 3500 Da.

[0013] The beneficial effects of the present invention: The polyamine shale inhibitor and its preparation method provided by the present invention show a significant improvement in inhibition performance under extreme working conditions through innovative molecular design and process optimization. The analysis of its beneficial effects is as follows: I. Significantly improve the shale inhibition performance under the composite conditions of high temperature / high salt / acid: According to the test data in Table 1, the rolling recovery rates of the polyamine shale inhibitors prepared in Examples 1-3 of the present invention are as high as 97.8% - 98.7% under the conditions of 180°C / 30% NaCl / pH = 3, which is 68.7% - 69.5% higher than that of Comparative Example 1 (58.2%), and far exceeds the prior art (<50%). The principle is as follows: (1) Dynamic covalent network construction: Through the dynamic exchange of borate bonds between 4-aminophenylboronic acid (4-APBA) and ethylenediamine, a temperature-responsive molecular network is formed. At high temperature (180°C), the dynamic bonds reversibly break and recombine, continuously repairing the defects of the adsorption layer (the rolling recovery rate drops sharply to 58.2% after removing 4-APBA in Comparative Example 1).

[0014] (2) Gradient sulfonation-phosphorylation modification: The gradient modification of concentrated sulfuric acid and trimethyl phosphate introduces sulfonic acid groups (-SO3H) and phosphate ester groups (-PO4). In a 30% NaCl high salinity environment, the charge shielding effect is resisted through strong hydration. The anti-calcium interference swelling rate of the examples (7.5% - 9.6%) is reduced by 80.5% - 84.2% compared with that of Comparative Example 1 (47.6%), proving that the multi-anion synergistic effect significantly improves the salt resistance.

[0015] (3) Reinforcement of the nanoconfinement effect: 2 - 3 nm of amino-functionalized graphene quantum dots (GQDs) are molecularly dispersed in a supercritical CO2 environment. The quantum size effect of GQDs generates strong adsorption sites, and hydrogen bond networks are formed between their amino groups and the hydroxyl groups on the shale surface, reducing the linear swelling rate to 5.9% - 7.3% (a reduction of 81.4% - 85.1% compared with 39.7% in Comparative Example 1).

[0016] II. Breaking through the bottleneck of molecular structure regulation in traditional preparation processes: When Comparative Example 2 uses the conventional solvent method (toluene replaces supercritical CO2), the rolling recovery rate is only 61.8%, which is 37.4% lower than that of Example 2 (98.7%), proving the key role of the supercritical process: (1) Plasticizing effect of supercritical CO2: Under a high pressure of 35 MPa, CO2 penetrates between polymer chain segments to lower the glass transition temperature, promoting the alternating copolymerization of ethylenediamine and epichlorohydrin.

[0017] (2) Nanoconfinement polymerization guidance: The low surface tension of the supercritical fluid enables GQDs to be uniformly dispersed in the polymerization system. Through π-π stacking interactions, the polymer chains are guided to grow directionally on the surface of the quantum dots, forming a three-dimensional interpenetrating network (the linear swelling rate of Example 2 is 5.9% vs. 22.1% of Comparative Example 3).

[0018] In summary, through the ternary coupling of 4-APBA / GQDs / supercritical process, the present invention breaks through the technical bottlenecks of insufficient rigidity and static modification of traditional polyamines. At the same time, the present invention develops a gradient sulfonation-phosphorylation modification process to achieve a spatial gradient distribution of anionic groups, and overcomes the industry problem of high desorption rate of inhibitors in high-salt environments. Through molecular structure innovation and process innovation, the present invention successfully solves the problem of shale inhibition in high-temperature / high-salt / acid composite formations. Detailed implementation manners

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention. The raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0020] Example 1

[0021] I. Raw materials and equipment for polyamine shale inhibitors: 1. Raw materials: Ethylenediamine (EDA, purity ≥ 99%, Sinopharm Group, CAS 107-15-3); Epichlorohydrin (ECH, purity ≥ 98%, Aladdin Chemistry, CAS 106-89-8); 4-Aminophenylboronic acid (4-APBA, purity 98%, Macklin, CAS 89415-43-0); Amino-functionalized graphene quantum dot powder (particle size 2 - 3 nm, Xianfeng Nano, model XF229); Concentrated sulfuric acid (H2SO4, 98%, Sinopharm Group); Trimethyl phosphate (TMP, analytical pure, Sinopharm Group, CAS 512-56-1); Supercritical CO2 (purity ≥ 99.9%, Nantong Hua'an Supercritical Extraction Co., Ltd.).

[0022] 2. Equipment: Supercritical reaction kettle (volume 5 L, pressure resistance 50 MPa, with magnetic stirring and temperature control system); High-pressure CO2 delivery system (pressure range 0 - 50 MPa, flow rate controllable); Vacuum drying oven (temperature range 0 - 200 °C, Shanghai Yiheng); Dialysis bag (cut-off molecular weight 3500 Da).

[0023] II. Preparation steps of polyamine shale inhibitor: 1. Preparation of dynamic covalent network-nanoconfined inhibitor: Step 1: Supercritical confinement polymerization: (1) Raw material pretreatment: Ethylenediamine and epichlorohydrin are respectively distilled under reduced pressure under nitrogen protection to remove moisture and low-boiling impurities; the amino-functionalized graphene quantum dot powder is vacuum-dried at 60 °C for 4 hours before use to avoid agglomeration.

[0024] (2) Feeding and loading the autoclave: Accurately weigh the raw materials according to the following molar ratios: Ethylenediamine: 100 g (1.67 mol); Epichlorohydrin: 180 g (1.94 mol, molar ratio EDA:ECH = 1:1.8); 4-Aminophenylboronic acid: 50 g (0.36 mol, molar ratio EDA:4-APBA = 1:0.5); Amino-functionalized graphene quantum dot powder: 12 g; Add the above raw materials into the supercritical autoclave, install the stirring paddle and seal it.

[0025] (3) Establishment of supercritical CO2 environment: Introduce supercritical CO2 into the supercritical autoclave until the pressure reaches 35 MPa, start magnetic stirring (rotation speed 300 rpm), heat up to 80 °C at a rate of 1 °C / min, and maintain the pressure at 35 MPa ± 0.5 MPa.

[0026] (4) Dynamic polymerization reaction: Under the conditions of 80 °C and 35 MPa ± 0.5 MPa, react continuously for 4 hours, and then monitor the viscosity of the system through an on-line viscometer. When the viscosity reaches 5000 ± 500 mPa·s, the reaction end point is determined.

[0027] Step 2: Gradient sulfonation-phosphorylation modification: (1) Sulfonation reaction: After the reaction end point, after the supercritical autoclave is depressurized to atmospheric pressure, slowly add 30 g of concentrated sulfuric acid (98%) (molar ratio EDA:H2SO4 = 1:0.3) to it, control the dropping rate at 4 mL / min, avoid local overheating, and stir and react at 55 °C and atmospheric pressure for 2 hours to generate a sulfonated intermediate.

[0028] (2)Phosphorylation reaction: 20 g of trimethyl phosphate (TMP) (molar ratio EDA:TMP = 1:0.2) was added to the supercritical reactor, the temperature was raised to 80° C., and the reaction was carried out for 2 hours under nitrogen protection. After the reaction was completed, the pH was adjusted to 6.5 with a 10% by mass NaOH solution to obtain a reaction solution.

[0029] Step 3: Post-treatment and purification: (1) Dialysis purification: The reaction solution was transferred to a dialysis bag (molecular weight cutoff 3500 Da) and dialyzed in deionized water for 48 h (changing the water every 8 h) to remove unreacted monomers and salts.

[0030] (2) Drying treatment: The dialyzed reaction solution was dried in a vacuum drying oven at 60° C. to constant weight to obtain a light blue powder product, namely, a polyamine shale inhibitor.

[0031] Example 2

[0032] 1. Raw materials and equipment of polyamine shale inhibitors: 1. Raw materials: Ethylenediamine (EDA, purity ≥99%, Sinopharm Group, CAS 107-15-3); Epichlorohydrin (ECH, purity ≥98%, Aladdin Chemical, CAS 106-89-8); 4-Aminophenylboronic acid (4-APBA, purity 98%, Maclean, CAS 89415-43-0); Aminated graphene quantum dot powder (particle size 2-3 nm, Xianfeng Nano, model XF229); Concentrated sulfuric acid (H2SO4, 98%, Sinopharm Group); Trimethyl phosphate (TMP, analytical grade, Sinopharm Group, CAS 512-56-1); Supercritical CO2 (purity ≥99.9%, Nantong Hua'an Supercritical Extraction Co., Ltd.).

[0033] 2. Equipment: Supercritical reactor (volume 5L, pressure resistance 50MPa, with magnetic stirring and temperature control system); High-pressure CO2 delivery system (pressure range 0-50MPa, flow controllable); Vacuum drying oven (temperature range 0~200℃, Shanghai Yiheng); Dialysis bag (MWCO 3500 Da).

[0034] 2. Preparation steps of polyamine shale inhibitors: 1. Preparation of Dynamic Covalent Network-Nano-confined Inhibitors: Step 1: Supercritical confinement polymerization: (1) Pretreatment of raw materials: Ethylenediamine and epichlorohydrin were separately distilled under reduced pressure under nitrogen protection to remove moisture and low-boiling impurities; the amino-functionalized graphene quantum dot powder was vacuum-dried at 60 °C for 4 hours before use to avoid agglomeration.

[0035] (2) Feeding and charging the autoclave: The raw materials were accurately weighed according to the following molar ratios: Ethylenediamine: 100 g (1.67 mol); Epichlorohydrin: 180 g (1.94 mol, molar ratio EDA:ECH = 1:1.8); 4-Aminophenylboronic acid: 50 g (0.36 mol, molar ratio EDA:4-APBA = 1:0.5); Amino-functionalized graphene quantum dot powder: 14 g; The above raw materials were added to the supercritical autoclave, and a stirring paddle was installed and sealed.

[0036] (3) Establishment of supercritical CO2 environment: Supercritical CO2 was introduced into the supercritical autoclave until the pressure reached 40 MPa. The magnetic stirring was started (rotation speed 300 rpm), and the temperature was raised to 90 °C at a rate of 2 °C / min, and the pressure was maintained at 35 MPa ± 0.5 MPa.

[0037] (4) Dynamic polymerization reaction: The reaction was continuously carried out at 90 °C and 35 MPa ± 0.5 MPa for 6 hours. Then, the viscosity of the system was monitored by an online viscometer. When the viscosity reached 5000 ± 500 mPa·s, the reaction end point was determined.

[0038] Step 2: Gradient sulfonation-phosphorylation modification: (1) Sulfonation reaction: After the reaction end point, the pressure in the supercritical autoclave was released to atmospheric pressure. Then, 30 g of concentrated sulfuric acid (98%) (molar ratio EDA:H2SO4 = 1:0.3) was slowly added dropwise thereto, and the dropping rate was controlled at 5 mL / min to avoid local overheating. The reaction was stirred at 60 °C and atmospheric pressure for 4 hours to generate a sulfonated intermediate.

[0039] (2) Phosphorylation reaction: Trimethyl phosphate (TMP) 20 g (molar ratio EDA:TMP = 1:0.2) was further added to the supercritical autoclave, and the temperature was raised to 85 °C. The reaction was carried out under nitrogen protection for 2.5 hours. After the reaction, the pH was adjusted to 7.0 with a 10% NaOH solution to obtain the reaction solution.

[0040] Step 3: Post-treatment and purification: (1) Dialysis purification: The reaction solution was transferred to a dialysis bag (molecular weight cutoff 3500 Da) and dialyzed in deionized water for 48 h (changing the water every 8 h) to remove unreacted monomers and salts.

[0041] (2) Drying treatment: The dialyzed reaction solution was dried in a vacuum drying oven at 80° C. to constant weight to obtain a light blue powder product, namely, a polyamine shale inhibitor.

[0042] Example 3

[0043] 1. Raw materials and equipment of polyamine shale inhibitors: 1. Raw materials: Ethylenediamine (EDA, purity ≥99%, Sinopharm Group, CAS 107-15-3); Epichlorohydrin (ECH, purity ≥98%, Aladdin Chemical, CAS 106-89-8); 4-Aminophenylboronic acid (4-APBA, purity 98%, Maclean, CAS 89415-43-0); Aminated graphene quantum dot powder (particle size 2-3 nm, Xianfeng Nano, model XF229); Concentrated sulfuric acid (H2SO4, 98%, Sinopharm Group); Trimethyl phosphate (TMP, analytical grade, Sinopharm Group, CAS 512-56-1); Supercritical CO2 (purity ≥99.9%, Nantong Hua'an Supercritical Extraction Co., Ltd.).

[0044] 2. Equipment: Supercritical reactor (volume 5L, pressure resistance 50MPa, with magnetic stirring and temperature control system); High-pressure CO2 delivery system (pressure range 0-50MPa, flow controllable); Vacuum drying oven (temperature range 0~200℃, Shanghai Yiheng); Dialysis bag (MWCO 3500 Da).

[0045] 2. Preparation steps of polyamine shale inhibitors: 1. Preparation of Dynamic Covalent Network-Nano-confined Inhibitors: Step 1: Supercritical confined polymerization: (1) Raw material pretreatment: Ethylenediamine and epichlorohydrin were distilled under reduced pressure under nitrogen protection to remove moisture and low-boiling impurities; the amination graphene quantum dot powder was vacuum dried at 60° C. for 4 hours before use to avoid agglomeration.

[0046] (2)Feeding and charging the autoclave: Accurately weigh the raw materials according to the following molar ratios: Ethylenediamine: 100 g (1.67 mol); Epichlorohydrin: 180 g (1.94 mol, molar ratio of EDA:ECH = 1:1.8); 4-Aminophenylboronic acid: 50 g (0.36 mol, molar ratio of EDA:4-APBA = 1:0.5); Aminated graphene quantum dot powder: 15 g; Add the above raw materials into the supercritical autoclave, install the stirring paddle and seal it.

[0047] (3)Establishment of supercritical CO2 environment: Introduce supercritical CO2 into the supercritical autoclave until the pressure reaches 40 MPa, start magnetic stirring (rotation speed 300 rpm), heat up to 90 °C at a rate of 5 °C / min, and maintain the pressure at 35 MPa ± 0.5 MPa.

[0048] (4)Dynamic polymerization reaction: React continuously for 6 hours at 90 °C and 35 MPa ± 0.5 MPa, and then monitor the viscosity of the system through an on-line viscometer. When the viscosity reaches 5000 ± 500 mPa·s, determine the end point of the reaction.

[0049] Step 2: Gradient sulfonation-phosphorylation modification: (1)Sulfonation reaction: After the end point of the reaction, release the pressure of the supercritical autoclave to atmospheric pressure, and slowly add 30 g of concentrated sulfuric acid (98%) (molar ratio of EDA:H2SO4 = 1:0.3) dropwise thereto, control the dropping rate at 5 mL / min, avoid local overheating, and stir and react at 60 °C and atmospheric pressure for 4 hours to generate a sulfonated intermediate.

[0050] (2)Phosphorylation reaction: Add 20 g of trimethyl phosphate (TMP) (molar ratio of EDA:TMP = 1:0.2) to the supercritical autoclave again, heat up to 85 °C, and react for 2.5 hours under nitrogen protection. After the reaction, adjust the pH to 7.0 with a 10% NaOH solution to obtain a reaction solution.

[0051] Step 3: Post-treatment and purification: (1)Dialysis purification: Transfer the reaction solution to a dialysis bag (cut-off molecular weight 3500 Da), and dialyze it in deionized water for 48 hours (change the water every 8 hours) to remove unreacted monomers and salts.

[0052] (2) Drying treatment: The dialyzed reaction solution was dried in a vacuum drying oven at 80° C. to constant weight to obtain a light blue powder product, namely, a polyamine shale inhibitor.

[0053] Comparative Example 1 (Removal of 4-aminophenylboronic acid) Comparative Example 1 is the control group of Example 2, in which the raw material 4-aminophenylboric acid in Example 2 is deleted, and the remaining raw materials, raw material amounts and preparation steps are kept consistent with those in Example 2, and finally a polyamine shale inhibitor is obtained.

[0054] Comparative Example 2 (Conventional solvent toluene instead of supercritical CO2) Comparative Example 2 is the control group of Example 2, in which toluene is used as a solvent to replace the supercritical CO2 environment, and other conditions are consistent with those of Example 2. The specific scheme is as follows: 1. Raw materials and equipment 1. Raw materials: Ethylenediamine (EDA, purity ≥99%, Sinopharm Group, CAS 107-15-3); Epichlorohydrin (ECH, purity ≥98%, Aladdin Chemical, CAS 106-89-8); 4-Aminophenylboronic acid (4-APBA, purity 98%, Maclean, CAS 89415-43-0); Aminated graphene quantum dot powder (particle size 2-3 nm, Xianfeng Nano, model XF229); Concentrated sulfuric acid (H2SO4, 98%, Sinopharm Group); Trimethyl phosphate (TMP, analytical grade, Sinopharm Group, CAS 512-56-1); Toluene (analytical grade, Sinopharm Group, CAS 108-88-3).

[0055] 2. Equipment: Conventional reactor (volume 5L, with magnetic stirring and temperature control system, made of 316L stainless steel); Vacuum drying oven (temperature range 0~200℃, Shanghai Yiheng); Dialysis bag (MWCO 3500 Da).

[0056] 2. Preparation steps (compared with Example 2) Step 1: Conventional solvent polymerization: (1) Raw material pretreatment: The pretreatment with ethylenediamine and epichlorohydrin is the same as in Example 2; The aminated graphene quantum dot powder was dried in vacuum at 60 °C for 4 h.

[0057] (2) Feeding and loading the kettle: Weigh the raw materials according to the molar ratio of Example 2: EDA: 100 g (1.67 mol); ECH: 180 g (1.94 mol); 4-APBA: 50 g (0.36 mol); Aminated graphene quantum dot powder: 14 g; Mix the raw materials with 500 mL of toluene and then add them to a conventional reaction kettle (without supercritical equipment).

[0058] (3) Dynamic polymerization reaction: Start magnetic stirring (rotation speed 300 rpm), heat up to 90 °C at a rate of 2 °C / min, and react at normal pressure (0.1 MPa) for 6 hours (Example 2 is under supercritical conditions of 35 MPa ± 0.5 MPa). Then, monitor the viscosity of the system through an online viscometer, and terminate the reaction when the viscosity reaches 5000 ± 500 mPa·s.

[0059] Step 2: Gradient sulfonation-phosphorylation modification: (1) Sulfonation reaction: After the reaction, slowly add 30 g of concentrated sulfuric acid (98%) (molar ratio EDA:H2SO4 = 1:0.3) to the conventional reaction kettle, control the dropping rate at 5 mL / min to avoid local overheating, and stir and react at 60 °C and normal pressure for 4 hours to generate a sulfonated intermediate.

[0060] (2) Phosphorylation reaction: Add 20 g of trimethyl phosphate (TMP) (molar ratio EDA:TMP = 1:0.2) to the conventional reaction kettle again, heat up to 85 °C, and react under nitrogen protection for 2.5 hours. After the reaction, adjust the pH to 7.0 with a 10% NaOH solution by mass to obtain a reaction solution.

[0061] Step 3: Post-treatment and purification: (1) Dialysis purification: The reaction solution is removed of toluene by rotary evaporation (60 °C, -0.09 MPa), and the remaining liquid is transferred to a dialysis bag (cut-off molecular weight 3500 Da) and dialyzed in deionized water for 48 hours (changing water every 8 hours) to remove unreacted monomers and salts.

[0062] (2) Drying treatment (the same as Example 2): The dialyzed reaction solution is dried in a vacuum drying oven at 80 °C to constant weight to obtain a light blue powdery product, that is, a polyamine shale inhibitor is obtained.

[0063] Comparative Example 3 (using SiO2 nanoparticles to replace aminated graphene quantum dot powder) Comparative Example 3 is the control group of Example 2. The amino-functionalized graphene quantum dot powder in Example 2 was replaced with SiO2 nanoparticles (20 nm, purity ≥ 99%), and the other raw materials, the amounts of raw materials, and the preparation steps were kept the same as those in Example 2, and finally a polyamine shale inhibitor was obtained.

[0064] Test Example 1 Performance tests were carried out on the polyamine shale inhibitors prepared in Examples 1 to 3 and Comparative Examples 1 to 3. The performance test process is as follows, and the test results are shown in Table 1: I. Rolling recovery rate test (180 °C / 30% NaCl / pH = 3): (1) Preparation of simulated drilling fluid: Raw materials: 300 g of sodium chloride (NaCl, analytical pure, purity ≥ 99.8%), 10 g of polyamine shale inhibitor (prepared in the above examples or comparative examples), hydrochloric acid (HCl, analytical pure), 690 mL of deionized water (conductivity ≤ 1 μS / cm).

[0065] Preparation steps: Add 690 mL of deionized water to a 2000 mL beaker, heat to 50 °C, then add 300 g of NaCl, and stir magnetically (500 rpm) until completely dissolved to obtain a 30% NaCl solution. Then, add concentrated hydrochloric acid dropwise thereto, stir for 30 seconds for each drop added until the pH is stabilized at 3.0 ± 0.05. If the pH is too low, it can be finely adjusted with 0.1 mol / L NaOH. After adjustment, add 10 g of polyamine shale inhibitor powder thereto and stir magnetically (800 rpm) for 1 hour to obtain the simulated drilling fluid.

[0066] (2) Test method: Take 10 g of 10-mesh shale particles, add simulated drilling fluid according to a liquid-solid ratio of 3:1 (that is, 3 mL of simulated drilling fluid is used for every 1 g of shale particles), heat-roll in an aging tank at 180 °C for 24 hours, pass through a 40-mesh sieve, and calculate the recovery rate: Recovery rate (%) = (residual mass / initial mass) × 100.

[0067] II. Linear expansion rate test (180 °C / 30% NaCl / 72 h): (1) Preparation of brine (30% NaCl) containing 2% polyamine shale inhibitor: Raw materials: 300 g of sodium chloride (NaCl, analytical pure, purity ≥ 99.8%), 20 g of polyamine shale inhibitor (prepared in the above examples or comparative examples), 680 mL of deionized water (conductivity ≤ 1 μS / cm).

[0068] Configuration steps: Add 680 mL of deionized water to a 2000 mL beaker, heat it to 50 °C, then add 300 g of NaCl, and stir magnetically (500 rpm) until completely dissolved to obtain a 30% NaCl solution. Then add 20 g of polyamine shale inhibitor powder to it and stir magnetically (800 rpm) for 1 hour to obtain brine (30% NaCl) containing 2% polyamine shale inhibitor.

[0069] (2) Test method: Immerse the shale core (with a diameter of 25 mm) in the above-mentioned brine (30% NaCl) containing 2% polyamine shale inhibitor, keep it at a constant temperature of 180 °C in a high-temperature tank for 72 hours, and use a digital micrometer to measure the swelling height: Swelling rate (%) = (height after swelling - initial height) / initial height × 100.

[0070] III. Calcium ion interference resistance test (5000 mg / L Ca 2+ ) (1) Preparation of drilling fluid containing 5000 mg / L Ca 2+ : Add 700 mL of deionized water to a 2000 mL beaker, heat it to 50 °C, then add 300 g of NaCl to it and stir until completely dissolved. Add 18.33 g of CaCl2·2H2O to the above solution and stir until completely dissolved. Transfer the solution to a 1000 mL volumetric flask, make up the volume to the calibration line with deionized water, and then stir magnetically (500 rpm) for 10 minutes to obtain drilling fluid containing 5000 mg / LCa 2+ .

[0071] (2) Test method: Add polyamine shale inhibitor to the drilling fluid containing 5000 mg / L Ca 2+ according to a mass ratio of 100:2, and measure the swelling rate at 180 °C / 24 h according to the linear swelling rate test method.

[0072] Table 1 Test results Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Rolling Recovery Rate (%) 97.8 98.7 98.5 58.2 61.8 72.4 Linear Expansion Rate (%) 7.3 5.9 6.8 39.7 38.5 22.1 Calcium-Interference-Resistant Expansion Rate (%) 9.6 7.5 8.9 47.6 43.2 28.3 It should be noted that in this article, terms such as "including, containing" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, article or device.

[0073] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polyamine shale inhibitor, characterized in that, It includes the following raw materials in parts by mass: 100 parts of ethylenediamine, 180 parts of epichlorohydrin, 50 parts of 4-aminophenylboronic acid, 12 - 15 parts of amino-functionalized graphene quantum dot powder, 30 parts of concentrated sulfuric acid, and 20 parts of trimethyl phosphate.

2. The polyamine shale inhibitor according to claim 1, wherein The particle size of the amino-functionalized graphene quantum dot powder is 2 - 3 nm.

3. The preparation method of a polyamine shale inhibitor according to any one of claims 1 to 2, characterized in that, It includes the following steps: Add ethylenediamine, epichlorohydrin, 4-aminophenylboronic acid, and amino-functionalized graphene quantum dot powder into a supercritical reactor, then introduce supercritical CO₂ into it to construct a supercritical environment and carry out a dynamic polymerization reaction. After completion, release the pressure of the supercritical reactor to atmospheric pressure, and then slowly dropwise add concentrated sulfuric acid into it, controlling the dropping rate at 4 - 5 mL / min, and stir and react at 55 - 60 °C and atmospheric pressure for 2 - 4 hours. After completion, add trimethyl phosphate into the supercritical reactor again, heat up to 80 - 85 °C, and react for 2 - 2.5 hours under nitrogen protection. After the reaction ends, adjust the pH to 6.5 - 7.0 with a 10% NaOH solution by mass fraction to obtain a reaction solution. After the reaction solution is dialyzed and dried, a polyamine shale inhibitor is obtained.

4. The preparation method of a polyamine shale inhibitor according to claim 3, characterized in that, The construction of the supercritical environment includes the following steps: Introduce supercritical CO₂ into the supercritical reactor until the pressure reaches 35 - 40 MPa, start magnetic stirring, and heat up to 80 - 90 °C at a rate of 1 - 5 °C / min, and maintain the pressure at 35 MPa ± 0.5 MPa.

5. The preparation method of a polyamine shale inhibitor according to claim 3, characterized in that, The dynamic polymerization reaction includes the following steps: Continuously react at 80 - 90 °C and 35 MPa ± 0.5 MPa for 4 - 6 hours, and then monitor the viscosity of the system through an online viscometer. When the viscosity reaches 5000 ± 500 mPa·s, determine the end point of the reaction.

6. The preparation method of a polyamine shale inhibitor according to claim 3, characterized in that, The dialysis and drying treatment includes the following steps: Transfer the reaction solution to a dialysis bag, dialyze it in deionized water for 48 hours, and dry the dialyzed reaction solution in a vacuum drying oven at 60 - 80 °C until a constant weight is reached.

7. The preparation method of a polyamine shale inhibitor according to claim 3, characterized in that, The mass fraction of the concentrated sulfuric acid is 98%.

8. The preparation method of a polyamine shale inhibitor according to claim 6, characterized in that, The cut-off molecular weight of the dialysis bag is 3500 Da.