Cationic amino inhibitor for drilling fluid as well as preparation method and application of cationic amino inhibitor

Abstract

The invention belongs to the field of treating agents for oil field drilling fluid, and particularly relates to a cationic amino inhibitor for drilling fluid as well as a preparation method and application of the cationic amino inhibitor. The cationic amino inhibitor for the drilling fluid provided by the invention contains a compound with a structure as shown in a formula (I) and / or a formula (II). The inhibitor provided by the invention contains the compound with the structure as shown in the formula (I) and / or the formula (II), and has relatively strong inhibition performance and good temperature resistance; the compounds with the structures as shown in the formula (I) and the formula (II) contain a large number of quaternary ammonium cations and hydroxyl groups, and can be adsorbed on the surface of shale or enter crystal lattices to tighten a crystal layer, reduce hydration and dispersion of the shale and keep the well wall stable in the drilling process. In addition, during synthesis and preparation of the inhibitor, reaction conditions are mild and easy to control, a chain growth terminator does not need to be added, and the product is not prone to cross-linking and good in quality stability. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the field of treating agents for oilfield drilling fluids, and in particular relates to a cationic amine inhibitor for drilling fluids, a preparation method and an application thereof. Background Art

[0002] During the drilling process, wellbore instability is the main factor causing downhole complexity, especially in strata containing large sections of shale. Due to the hydration and dispersion of shale, wellbore collapse is very frequent. According to statistics, wellbore instability caused by hydration and dispersion of shale accounts for more than 90% of the incidence of wellbore instability. Inhibitors are a common treatment agent for drilling fluids that can inhibit the hydration and dispersion of shale and maintain the stability of the wellbore. Common drilling fluid inhibitors mainly include asphalt, polymers and inorganic salts. However, asphalt is not conducive to environmental protection, silicates will make it difficult to control the rheology of drilling fluids, potassium salts are used in large quantities, and polyethylene glycols have relatively poor inhibition performance. Amine inhibitors are currently the best inhibitor variety in field applications, with advantages such as low dosage and strong inhibition performance.

[0003] Chinese patent application number 201510534350.0 discloses a polyamine inhibitor and a preparation method thereof, which is obtained by reacting a polyamine compound with epichlorohydrin; Chinese patent application number 201110313847.1 discloses a polyamine inhibitor and a preparation method thereof, which is obtained by reacting a terminal diamine, a cyclic ether and epichlorohydrin. The amine compounds used in the above two schemes mainly contain primary amines and secondary amines, which are prone to severe crosslinking when reacting with epichlorohydrin, the reaction conditions are difficult to control, and the product quality stability is poor. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a cationic amine inhibitor for drilling fluid and a preparation method and application thereof. The inhibitor provided by the present invention has strong inhibitory performance, quaternary ammonium cations are distributed on the main chain of the molecule, and has good temperature resistance, and is very suitable for application in high-temperature resistant water-based drilling fluid systems; and the preparation conditions of the inhibitor are mild and easy to control, without the need to add a chain growth terminator, the product is not easy to cross-link, and has good quality stability.

[0005] The present invention provides a cationic amine inhibitor for drilling fluid, wherein the cationic amine inhibitor for drilling fluid contains a compound of formula (I) and / or formula (II):

[0006]

[0007] In formula (I) to (II), R is C 1 ~C 10 wherein n is an integer between 1 and 10, and m is an integer between 5 and 200.

[0008] Preferably, the R is -CH 3 or -CH 2 CH 3 .

[0009] Preferably, n is an integer between 2 and 4.

[0010] Preferably, m is an integer between 5 and 100.

[0011] Preferably, the cationic amine-based inhibitor for drilling fluid further contains a liquid medium; the solid content of the cationic amine-based inhibitor for drilling fluid is 10-40wt%.

[0012] The present invention provides a method for preparing the cationic amine inhibitor for drilling fluid described in the above technical solution, comprising the following steps:

[0013] a) mixing an amino compound of formula (i) with a first epichlorohydrin in a liquid medium to react to obtain an intermediate;

[0014]

[0015] In formula (i), R is C 1 ~C 10 An alkyl group, n is an integer between 1 and 10;

[0016] b) the intermediate is mixed with an inorganic acid for acidification, wherein the inorganic acid is hydrochloric acid and / or sulfuric acid; and then mixed with a second epichlorohydrin for reaction to obtain a cationic amine inhibitor for drilling fluid.

[0017] Preferably, the amino compound is N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine, N,N-dimethylbutylenediamine, N,N-diethylethylenediamine, N,N-diethylpropylenediamine or N,N-diethylbutylenediamine.

[0018] Preferably, the molar ratio of the amino compound, the first epichlorohydrin, the inorganic acid and the second epichlorohydrin is 1:(1-1.1):(0.8-1.5):(1-3).

[0019] Preferably, in step a), the temperature of the mixed reaction is 40 to 70° C., and the time of the mixed reaction is 0.5 to 2 h;

[0020] In step b), the temperature of the mixed acidification is 10-40° C., and the time of the mixed acidification is 5-30 min; the temperature of the mixed reaction is 50-90° C., and the time of the mixed reaction is 2-6 h.

[0021] The present invention provides a drilling fluid, wherein the drilling fluid contains the cationic amine-based inhibitor for drilling fluid described in the above technical solution or the cationic amine-based inhibitor for drilling fluid prepared by the preparation method described in the above technical solution.

[0022] Compared with the prior art, the present invention provides a cationic amine inhibitor for drilling fluid and a preparation method and application thereof. The cationic amine inhibitor for drilling fluid provided by the present invention contains a compound of formula (I) and / or formula (II); in formula (I) to (II), R is C 1 ~C 10 alkyl, n is an integer between 1 and 10, and m is an integer between 5 and 200. The inhibitor provided by the present invention contains compounds of the structure of formula (I) and / or formula (II), has strong inhibitory performance, and good temperature resistance; the compounds of the structure of formula (I) and formula (II) contain a large amount of quaternary ammonium cations and hydroxyl groups, which can be adsorbed on the surface of shale or enter the interior of the crystal lattice, tighten the crystal layer, reduce the hydration and dispersion of shale, and maintain the stability of the well wall during drilling. In addition, the inhibitor provided by the present invention has mild reaction conditions during synthesis and preparation, is easy to control, does not need to add chain growth terminator, is not easy to cross-link, and has good quality stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 The invention provides a synthetic route for the cationic amine inhibitor for drilling fluid. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The present invention provides a cationic amine inhibitor for drilling fluid, wherein the cationic amine inhibitor for drilling fluid contains a compound of formula (I) and / or formula (II):

[0027]

[0028] In formula (I) to (II), R is C 1 ~C10 wherein n is an integer between 1 and 10, and m is an integer between 5 and 200.

[0029] In the cationic amine inhibitor for drilling fluid provided by the present invention, in the compounds of formula (I) and formula (II), the R can be specifically C 1 Alkyl (i.e., -CH 3 ), C 2 Alkyl (i.e., -CH 2 CH 3 ), C 3 Alkyl, C 4 Alkyl, C 5 Alkyl, C 6 Alkyl, C 7 Alkyl, C 8 Alkyl, C 9 Alkyl or C 10 Alkyl, preferably -CH 3 or -CH 2 CH 3 .

[0030] In the cationic amine inhibitor for drilling fluid provided by the present invention, in the structural compounds of formula (I) and formula (II), the n can be specifically 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, preferably an integer between 2 and 4.

[0031] In the cationic amine inhibitor for drilling fluid provided by the present invention, in the structural compounds of formula (I) and formula (II), the m can be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200, preferably an integer between 5 and 100.

[0032] In the cationic amine-based inhibitor for drilling fluid provided by the present invention, in order to facilitate the addition and use of the inhibitor in the drilling fluid, the cationic amine-based inhibitor for drilling fluid preferably also contains a liquid medium, and the liquid medium includes but is not limited to water; the solid content of the amine-based inhibitor for drilling fluid is preferably 10 to 40wt%, specifically 10wt%, 12wt%, 15wt%, 17wt%, 20wt%, 23wt%, 25wt%, 27wt%, 30wt%, 32wt%, 35wt%, 37wt% or 40wt%.

[0033] The cationic amine inhibitor for drilling fluid provided by the present invention contains compounds with structures of formula (I) and / or formula (II), has strong inhibitory performance and good temperature resistance; the compounds with structures of formula (I) and formula (II) contain a large amount of quaternary ammonium cations and hydroxyl groups, which can be adsorbed on the surface of shale or enter the interior of the crystal lattice, tighten the crystal layer, reduce the hydration and dispersion of shale, and maintain the stability of the well wall during drilling.

[0034] The present invention also provides a method for preparing the cationic amine inhibitor for drilling fluid described in the above technical solution, comprising the following steps:

[0035] a) mixing an amino compound of formula (i) with a first epichlorohydrin in a liquid medium to react to obtain an intermediate;

[0036]

[0037] In formula (i), R is C 1 ~C 10 An alkyl group, n is an integer between 1 and 10;

[0038] b) the intermediate is mixed with an inorganic acid for acidification, wherein the inorganic acid is hydrochloric acid and / or sulfuric acid; and then mixed with a second epichlorohydrin for reaction to obtain a cationic amine inhibitor for drilling fluid.

[0039] In the preparation method provided by the present invention, the synthesis route of the cationic amine inhibitor for drilling fluid is as follows: Figure 1 As shown, Figure 1 The invention provides a synthetic route for the cationic amine inhibitor for drilling fluid.

[0040] In the preparation method provided by the present invention, in step a), in the amino compound of formula (i), R can be specifically C 1 Alkyl (i.e., -CH 3 ), C 2 Alkyl (i.e., -CH 2 CH 3 ), C 3 Alkyl, C 4 Alkyl, C 5 Alkyl, C 6 Alkyl, C 7 Alkyl, C 8 Alkyl, C 9 Alkyl or C 10 Alkyl, preferably -CH 3 or -CH 2 CH 3 ; The n can specifically be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, preferably an integer between 2 and 4.

[0041] In the preparation method provided by the present invention, in step a), the amino compound can be more specifically selected from N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine, N,N-dimethylbutylenediamine, N,N-diethylethylenediamine, N,N-diethylpropylenediamine or N,N-diethylbutylenediamine.

[0042] In the preparation method provided by the present invention, in step a), the molar ratio of the amino compound to the first epichlorohydrin is preferably 1:(1-1.1), specifically 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09 or 1:1.1.

[0043] In the preparation method provided by the present invention, in step a), the liquid medium includes but is not limited to water; the amount of the liquid medium is determined according to the solid content of the cationic amine inhibitor for drilling fluid to be prepared, and the solid content is the percentage of the total mass of the amino compound, epichlorohydrin and inorganic acid to the total mass of the amino compound, epichlorohydrin, inorganic acid and liquid medium.

[0044] In the preparation method provided by the present invention, in step a), the temperature of the mixed reaction is preferably 40-70°C, specifically 40°C, 42°C, 45°C, 47°C, 50°C, 52°C, 55°C, 57°C, 60°C, 62°C, 65°C, 67°C or 70°C; the time of the mixed reaction is preferably 0.5-2h, specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h.

[0045] In the preparation method provided by the present invention, in step a), the specific process of the mixed reaction is preferably: first dissolving the amino compound in a liquid medium to obtain an amino compound solution; then slowly adding the first epichlorohydrin to the amino compound solution under stirring conditions; after the first epichlorohydrin is added, heating to the reaction temperature for reaction; after the reaction is completed, cooling to obtain an intermediate. The reaction temperature corresponds to the temperature of the mixed reaction described above; the time for the reaction after heating to the reaction temperature corresponds to the time of the mixed reaction described above.

[0046] In the preparation method provided by the present invention, in step b), the molar ratio of the inorganic acid to the amino compound of the intermediate preparation raw material formula (i) is preferably (0.8-1.5):1, specifically 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1 or 1.5:1.

[0047] In the preparation method provided by the present invention, in step b), the temperature of the mixed acidification is preferably 10-40°C, specifically 10°C, 12°C, 15°C, 17°C, 20°C, 23°C, 25°C (room temperature), 27°C, 30°C, 32°C, 35°C, 37°C or 40°C; the time of the mixed acidification is preferably 5-30min, specifically 5min, 7min, 10min, 12min, 15min, 17min, 20min, 23min, 25min, 27min or 30min.

[0048] In the preparation method provided by the present invention, in step b), the molar ratio of the second epichlorohydrin to the amino compound of the intermediate preparation raw material formula (i) is preferably (1-3):1, specifically 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3:1.

[0049] In the preparation method provided by the present invention, in step b), the temperature of the mixed reaction is preferably 50-90°C, specifically 50°C, 52°C, 55°C, 57°C, 60°C, 62°C, 65°C, 67°C, 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, 87°C or 90°C; the time of the mixed reaction is preferably 2-6h, specifically 2h, 2.3h, 2.5h, 2.7h, 3h, 3.2h, 3.5h, 3.7h, 4h, 4.2h, 4.5h, 4.7h, 5h, 5.2h, 5.5h, 5.7h or 6h.

[0050] In the preparation method provided by the present invention, in step b), the specific process of the mixed acidification and mixed reaction is preferably: adding an inorganic acid to the intermediate prepared in step a) for acidification treatment to obtain an acidified product; then slowly adding the second epichlorohydrin to the acidified product under stirring conditions; after the second epichlorohydrin is added, heating to the reaction temperature for reaction; after the reaction is completed, cooling to obtain a cationic amine inhibitor for drilling fluid with a certain solid content. Among them, the acidification treatment corresponds to the mixed acidification described above; the reaction temperature corresponds to the temperature of the mixed reaction described above; the time for the reaction after heating to the reaction temperature corresponds to the time of the mixed reaction described above.

[0051] The preparation method of the cationic amine inhibitor for drilling fluid provided by the invention has mild reaction conditions, is easy to control, does not need to add a chain growth terminator, and the inhibitor product is not easy to cross-link and has good quality stability.

[0052] The present invention also provides a drilling fluid, comprising a drilling fluid base slurry and an inhibitor, wherein the inhibitor is the cationic amine-based inhibitor for drilling fluid described in the above technical solution or the cationic amine-based inhibitor for drilling fluid prepared by the preparation method described in the above technical solution.

[0053] In the drilling fluid provided by the present invention, the drilling fluid base slurry contains water and bentonite; the drilling fluid base slurry also preferably contains other functional components, including but not limited to sodium carbonate.

[0054] In the drilling fluid provided by the present invention, the added content of the inhibitor is preferably 0.1-5wt%, more preferably 0.5-2wt%, specifically 0.5wt%, 1wt%, 1.5wt% or 2wt%.

[0055] For the purpose of greater clarity, the invention is described in detail through the following examples.

[0056] Example 1

[0057] 1 mol of N,N-dimethylpropylenediamine was dissolved in 1664 g of deionized water, mixed well and added to a reaction container, 1.05 mol of epichlorohydrin was slowly added at room temperature and under stirring conditions, after the epichlorohydrin was added, the temperature in the reaction container was controlled at 60° C. for 2 h, cooled to room temperature, 0.8 mol of sulfuric acid (mass concentration 98%) was added to the reaction container for acidification for 15 min, and then 1.5 mol of epichlorohydrin was slowly added, the temperature in the reaction container was controlled at 50° C. for 4 h, and cooled to room temperature to obtain a cationic amine inhibitor for drilling fluid with a solid content of 20%, whose chemical structure is shown in the following formula:

[0058]

[0059] Among them, m=30.

[0060] Example 2

[0061] 1 mol of N,N-diethylethylenediamine was dissolved in 3149 g of deionized water, mixed well and added to a reaction container, 1 mol of epichlorohydrin was slowly added at room temperature and under stirring conditions, after the epichlorohydrin was added, the temperature in the reaction container was controlled at 70°C for reaction for 1.5 hours, cooled to room temperature, 1.2 mol of hydrochloric acid (mass concentration 36%) was added to the reaction container for acidification for 30 minutes, and then 1 mol of epichlorohydrin was slowly added, the temperature in the reaction container was controlled at 70°C for reaction for 6 hours, and cooled to room temperature to obtain a cationic amine inhibitor for drilling fluid with a solid content of 10%, whose chemical structure is shown in the following formula:

[0062]

[0063] Among them, m=5.

[0064] Example 3

[0065] 1 mol of N,N-diethylbutanediamine was dissolved in 770 g of deionized water, mixed well and added to a reaction container, 1.1 mol of epichlorohydrin was slowly added under room temperature and stirring conditions, after the epichlorohydrin was added, the temperature in the reaction container was controlled at 40° C. to react for 0.5 h, cooled to room temperature, 1.5 mol of hydrochloric acid (mass concentration 36%) was added to the reaction container for acidification for 5 min, and then 3 mol of epichlorohydrin was slowly added, the temperature in the reaction container was controlled at 90° C. to react for 2 h, and cooled to room temperature to obtain a cationic amine inhibitor for drilling fluid with a solid content of 40%, whose chemical structure is shown in the following formula:

[0066]

[0067] Among them, m=100.

[0068] Embodiments 4 to 6

[0069] The steps are the same as those in Example 1, and the reaction substances and their amounts are shown in Table 1:

[0070] Table 1 Reaction substances and dosage

[0071]

[0072]

[0073] Performance Evaluation

[0074] The performance of the cationic amine inhibitors synthesized in Examples 1 to 6 was evaluated, and the specific evaluation contents are as follows:

[0075] (1) Relative inhibition rate

[0076] Add 50 g (accurate to 0.01 g) of sodium carbonate and 1000 g (accurate to 0.01 g) of bentonite for drilling fluid into 10 L of distilled water, stir at high speed for 2 h, and place at room temperature for curing for 24 h to obtain a 10% fresh water base slurry.

[0077] Take 7 portions of 400 mL 10% fresh water base slurry, add 4 g (accurate to 0.01 g) of the cationic amine inhibitor synthesized in Examples 1 to 6 to each of 6 portions, stir the 7 samples at 10000 r / min for 20 min using a high-speed stirrer, then heat roll at 150° C. for 16 h, and stir at 10000 r / min for 5 min after cooling. The rheological parameters of the base slurry are measured at room temperature using a six-speed rotation viscometer, and the relative inhibition rate of the inhibitor is calculated. The calculation formula of the relative inhibition rate is as follows:

[0078]

[0079] Among them, (φ 100 ) 0 It is the reading of the six-speed rotary viscometer of the base slurry at 100r / min when no inhibitor is added; (φ 100 ) 1 It is the reading of a six-speed rotation viscometer at 100 r / min after adding the inhibitor.

[0080] The calculation results are shown in Table 2:

[0081] Table 2 Evaluation of inhibition performance of cationic amine inhibitors

[0082] Example Relative inhibition rate, % 1 92.1 2 86.0 3 97.7 4 95.6 5 95.2 6 92.8

[0083] 4 g (accurate to 0.01 g) of the cationic amine inhibitor synthesized in Example 3 was added to 400 mL of 10% fresh water slurry, and the mixture was hot rolled for 16 h at different temperatures. The rheological parameters of the slurry were measured using a six-speed rotary viscometer at room temperature, and the relative inhibition rate of the inhibitor was calculated. The calculation results are shown in Table 3:

[0084] Table 3 Evaluation of the temperature resistance of cationic amine inhibitors

[0085] Temperature / ℃ Relative inhibition rate, % 120 95.9 150 97.7 180 98.6 200 99.1

[0086] (2) Shale recovery rate

[0087] Take 2.0-3.8 mm shale and dry it at 105±3°C to constant weight, then cool it to room temperature; prepare 350 mL of 1% aqueous solution with the cationic amine inhibitor synthesized in Examples 1-6, weigh 10 g of shale (G0) and put it into clean water and 1% cationic amine inhibitor aqueous solution respectively, roll it at 150°C for 16 hours, take it out after cooling, recover the core with a 0.42 mm pore size sieve, dry it at 105±3°C to constant weight, cool it to room temperature and weigh the recovered core mass (G1), and calculate the shale recovery rate using the following formula:

[0088]

[0089] The calculation results are shown in Table 4:

[0090] Table 4 Cationic amine inhibitor shale recovery

[0091] Example Shale recovery rate, % Shimizu 25.6 1 92.8 2 86.5 3 98.2 4 96.3 5 95.4 6 93.0

[0092] 350 mL of 1% aqueous solution was prepared using the amine inhibitor synthesized in Example 3, 10 g of shale (G0) was weighed and placed in clean water and 1% cationic amine inhibitor aqueous solution, respectively, and rolled at different temperatures for 16 h. After cooling, the core was taken out and recovered with a 0.42 mm pore size sieve, and dried to constant weight at 105±3° C. The shale recovery rate was calculated. The calculation results are shown in Table 5:

[0093] Table 5 Evaluation of the temperature resistance of cationic amine inhibitors

[0094]

[0095]

[0096] Performance evaluation shows that the cationic amine inhibitor synthesized in the present invention has good inhibition and temperature resistance, can still maintain good inhibition at 200° C., and can be used in high-temperature resistant drilling fluid systems.

[0097] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cationic amine inhibitor for drilling fluid, It is characterized in that The cationic amine inhibitor for drilling fluid contains compounds of formula (I) and / or formula (II): In formula (I) to (II), R is C 1 ~C 10 wherein n is an integer between 1 and 10, and m is an integer between 5 and 200.

2. The cationic amine inhibitor for drilling fluid according to claim 1, It is characterized in that The R is -CH 3 or -CH 2 CH 3 .

3. The cationic amine inhibitor for drilling fluid according to claim 1, It is characterized in that The n is an integer between 2 and 4.

4. The cationic amine inhibitor for drilling fluid according to claim 1, It is characterized in that The m is an integer between 5 and 100.

5. The cationic amine inhibitor for drilling fluid according to claim 1, It is characterized in that The cationic amine inhibitor for drilling fluid also contains a liquid phase medium; the solid content of the cationic amine inhibitor for drilling fluid is 10-40wt%.

6. A method for preparing the cationic amine inhibitor for drilling fluid according to any one of claims 1 to 5, It is characterized in that The following steps are involved: a) mixing an amino compound of formula (i) with a first epichlorohydrin in a liquid medium to react to obtain an intermediate; In formula (i), R is C 1 ~C 10 An alkyl group, n is an integer between 1 and 10; b) the intermediate is mixed with an inorganic acid for acidification, wherein the inorganic acid is hydrochloric acid and / or sulfuric acid; and then mixed with a second epichlorohydrin for reaction to obtain a cationic amine inhibitor for drilling fluid.

7. The preparation method according to claim 6, It is characterized in that The amino compound is N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine, N,N-dimethylbutylenediamine, N,N-diethylethylenediamine, N,N-diethylpropylenediamine or N,N-diethylbutylenediamine.

8. The preparation method according to claim 6, It is characterized in that The molar ratio of the amino compound, the first epichlorohydrin, the inorganic acid and the second epichlorohydrin is 1:(1-1.1):(0.8-1.5):(1-3).

9. The preparation method according to claim 6, It is characterized in that In step a), the temperature of the mixed reaction is 40 to 70° C., and the time of the mixed reaction is 0.5 to 2 h; In step b), the temperature of the mixed acidification is 10-40° C., and the time of the mixed acidification is 5-30 min; the temperature of the mixed reaction is 50-90° C., and the time of the mixed reaction is 2-6 h.

10. A drilling fluid, It is characterized in that The drilling fluid contains the cationic amine inhibitor for drilling fluid according to any one of claims 1 to 5 or the cationic amine inhibitor for drilling fluid prepared by the preparation method according to any one of claims 6 to 9.

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