A modified graphene oxide plugging agent and a preparation method thereof

Abstract

The application relates to the technical field of plugging materials, in particular to a modified graphene oxide plugging agent and a preparation method thereof, and the preparation comprises the following steps: S1, reacting phosphoric acid and an alcohol amine substance to obtain product intermediate A; S2, reacting graphene oxide with the product intermediate A obtained in the step S1 to obtain product intermediate B; and S3, reacting the product intermediate B with acryloxyethyl trimethyl ammonium chloride under the catalysis of ferric chloride to obtain the modified graphene oxide plugging agent. The preparation method of the drilling fluid plugging material provided by the application grafts phosphoric acid groups to graphene oxide, utilizes the hydrophilicity of the phosphoric acid groups, increases the dispersibility of the graphene oxide in water, and prevents the graphene oxide from easily agglomerating in the drilling fluid; the prepared plugging agent has a particle size distribution of 24.09-57.19 nm, and can effectively plug nanoscale cracks and pores.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of plugging materials, in particular to a modified graphene oxide plugging agent and a preparation method thereof BACKGROUND

[0002] With the increasing exploration of unconventional oil and gas resources, the requirements for drilling technology are also increasing, and the traditional drilling fluid is increasingly difficult to be efficiently applied to unconventional oil and gas exploitation. In the exploitation process of shale gas, wellbore stability has always been a difficult problem in the world. Wellbore instability can lead to a series of downhole complex situations such as leakage, spraying, sticking and inclination, prolong the drilling cycle, increase the drilling cost and affect the economic benefit.

[0003] The shale formation has the characteristics of low permeability, micropore and microcrack, so that the conventional drilling fluid composition cannot effectively plug the nanoscale cracks and pores in the shale formation. At present, the commonly used oil-based drilling fluid at home and abroad has poor environmental protection, therefore, it is of great significance to synthesize a nanometer plugging agent and apply it to the water-based drilling fluid. SUMMARY

[0004] The application provides a drilling fluid plugging material and a preparation method thereof, which can effectively solve the above problems.

[0005] The first aspect of the application provides a preparation method of a drilling fluid plugging material, comprising the following steps:

[0006] S1, phosphoric acid and an alcohol amine substance are added into a three-necked flask containing water, nitrogen is introduced, stirring is carried out, water bath heating is carried out at a temperature of 40-60 DEG C for 2-6h, after the reaction is completed, water in the product intermediate A is separated by reduced pressure distillation, the molar ratio of the phosphoric acid and the alcohol amine substance is (2.8-3.2): 1;

[0007] S2, graphene oxide is weighed and placed in pure water, ultrasonic dispersion is carried out for 20-40min, the suspension of graphene oxide is obtained, then the product intermediate A obtained in the step S1 is added, stirring is carried out at 20-25 DEG C, and propyl phosphonic anhydride is added dropwise, the dropwise addition is completed within 1.5h, the reaction mixture is further stirred overnight, after the reaction is completed, water washing and drying are carried out, and the product intermediate B is obtained;

[0008] S3, the product intermediate B obtained in the step S2 is added into a three-necked flask containing water, acryloxyethyl trimethyl ammonium chloride is further added, and a ferric chloride solution is further added, stirring is carried out at 20-25 DEG C for 12-16h, after the reaction is completed, water washing and drying are carried out, and the modified graphene oxide plugging agent is obtained.

[0009] In the step S1, the alcohol amine substance is one of ethanol amine, isopropanol amine and 2-amino-2-methyl-1-propanol.

[0010] In step S2, the product intermediate A: graphene oxide = (5-6): 1 by mass ratio;

[0011] In step S3, the product intermediate B: acryloxyethyl trimethyl ammonium chloride = 1: (18-22) by mass ratio.

[0012] The second aspect of the present application provides a drilling fluid plugging material prepared by the above preparation method.

[0013] The technical scheme of the embodiment of the present application has at least the following advantages and beneficial effects:

[0014] The preparation method of the drilling fluid plugging material provided by the present application grafts phosphoric acid groups to graphene oxide, uses the hydrophilicity of the phosphoric acid groups to increase the dispersibility of graphene oxide in water, and the prepared plugging agent has a particle size distribution of 24.09-57.19 nm, which can effectively plug nanoscale cracks and pores. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The particle size distribution graph of the modified graphene oxide in Example 1;

[0016] Figure 2 The particle size distribution graph of the modified graphene oxide in Example 2;

[0017] Figure 3 The particle size distribution graph of the modified graphene oxide in Example 3. DETAILED DESCRIPTION

[0018] The technical scheme of the present application will be described clearly and completely in combination with the embodiments of the present application. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application

[0019] The embodiments of the present application are as follows:

[0020] Example 1

[0021] S1, 19.6g of phosphoric acid and 36.65g of ethanolamine were added to a three-necked flask containing 250mL of water, then nitrogen was introduced into the flask, magnetic stirring was started, and the constant speed stirring was carried out at 300rpm, and the water bath heating was carried out at 50℃ for 3h. After the reaction was completed, the water in the reaction system was separated by reduced pressure distillation to obtain the product intermediate A;

[0022] S2, 2g of graphene oxide was weighed and placed in 50mL of pure water, ultrasonic dispersion for 30min, to obtain a suspension of graphene oxide, then 10g of product intermediate A obtained in step S1 was added, stirred at 25°C and 5mL of propyl phosphonic anhydride was added dropwise, dropwise addition was completed within 1.5h, the reaction mixture was further stirred overnight, after the reaction was completed, washed with water, dried to obtain product intermediate B;

[0023] S3, 10g of product intermediate B obtained in step S2 was added to a three-necked flask containing 50mL of water, then 200g of acryloyloxyethyl trimethyl ammonium chloride was added, then 10g of iron chloride solution was added, stirred at 25°C for 14h, after the reaction was completed, washed with water, dried to obtain the modified graphene oxide plugging agent.

[0024] Example 2

[0025] S1, 19.6g of phosphoric acid and 45.07g of isopropyl alcohol amine were added to a three-necked flask containing 250mL of water, then nitrogen was introduced, magnetic stirring was started, constant stirring at 300rpm, water bath heating at 50°C for 3h, after the reaction was completed, the water was separated by distillation under reduced pressure, to obtain product intermediate A;

[0026] S2, 2g of graphene oxide was weighed and placed in 50mL of pure water, ultrasonic dispersion for 30min, to obtain a suspension of graphene oxide, then 10.6g of product intermediate A obtained in step S1 was added, stirred at 25°C and 5mL of propyl phosphonic anhydride was added dropwise, dropwise addition was completed within 1.5h, the reaction mixture was further stirred overnight, after the reaction was completed, washed with water, dried to obtain product intermediate B;

[0027] S3, 10g of product intermediate B obtained in step S2 was added to a three-necked flask containing 50mL of water, then 200g of acryloyloxyethyl trimethyl ammonium chloride was added, then 10g of iron chloride solution was added, stirred at 25°C for 14h, after the reaction was completed, washed with water, dried to obtain the modified graphene oxide plugging agent.

[0028] Example 3

[0029] S1, 19.6g of phosphoric acid and 53.48g of 2-amino-2-methyl-1-propanol were added to a three-necked flask containing 250mL of water, then nitrogen was introduced, magnetic stirring was started, constant stirring at 300rpm, water bath heating at 50°C for 3h, after the reaction was completed, the water was separated by distillation under reduced pressure, to obtain product intermediate A;

[0030] S2, 2 g of graphene oxide was weighed and placed in 50 mL of pure water, ultrasonic dispersion for 30 min to obtain a suspension of graphene oxide, then 11.2 g of product intermediate A obtained in step S1 was added, 5 mL of propyl phosphonic anhydride was added dropwise under stirring at 25°C, and the dropwise addition was completed within 1.5 h, the reaction mixture was further stirred overnight, after the reaction was completed, it was washed with water and dried to obtain product intermediate B;

[0031] S3, 10 g of product intermediate B obtained in step S2 was added to a three-necked flask containing 50 mL of water, 200 g of acryloxyethyl trimethyl ammonium chloride was added, and 10 g of iron chloride solution was added, and the reaction was stirred at 25°C for 14 h, after the reaction was completed, it was washed with water and dried to obtain the modified graphene oxide plugging agent.

[0032] Comparative Example 1

[0033] Comparative Example 1 is a commonly used plugging material MB-1 (a rigid plugging material mainly composed of barium sulfate).

[0034] Preparation of water-based drilling fluid:

[0035] 120 parts of bentonite was slowly added to 2000 parts of water under high stirring, stirred for 30 min, then 10 parts of anhydrous sodium carbonate was added, stirred for 20 min, after the stirring was completed, it was sealed and placed for 24 h; the drilling fluid was stirred uniformly at low speed for 20 min after standing for 24 h, then 80 parts of filter loss reducer SMP-1 was added and stirred for 10 min; 80 parts of SMC was added and stirred for 10 min; 3 parts of HF-1 was added and stirred for 10 min; 180 parts of micro sphalerite powder was added and stirred uniformly for 30 min.

[0036] The modified graphene oxide plugging agent in Example 1, Example 2, Example 3 and the MB-1 plugging agent in Comparative Example 1 were respectively added to the drilling fluid in an amount of 0%, 1%, 2%, 3% and 4% by mass fraction and stirred uniformly for 10 min. Then they were respectively loaded into an aging tank and hot-rolled at a temperature of 120°C for 16 h. The rheological properties of the drilling fluids were tested, then the drilling fluids were added to a high temperature and high pressure filter loss instrument, and a mud cake was pressed at a temperature of 150°C and a pressure of 3.5 MPa for 30 min to obtain the high temperature and high pressure water loss and calculate the permeability and plugging rate of the mud cake.

[0037] Table 1: Test data of drilling fluid rheological properties and plugging properties

[0038]

[0039] As shown in the data in Table 1, the modified graphene oxide synthesized in the application has good plugging effect as a plugging agent, and with the increase of the amount, the permeability gradually decreases and the plugging rate gradually increases. Considering the plugging effect and economic benefits comprehensively, when the amount of the modified graphene oxide plugging agent is 3%, the effect is best. Compared with the performance of the water-based drilling fluid using the rigid plugging material MB-I in Comparative Example 1 as a plugging agent, the water-based drilling fluid using the modified graphene oxide in the application as a plugging agent has lower high-temperature and high-pressure filtration loss and permeability and higher plugging rate. Therefore, the water-based drilling fluid prepared by using the modified graphene oxide plugging agent synthesized in the application has better performance.

[0040] The above description is only the preferred embodiment of the present application, and does not limit the present application in any form, and any modification, equivalent change and modification of the above embodiment according to the technical essence of the present application without departing from the technical solution range of the present application still belongs to the technical solution range of the present application.

Claims

1. A method for preparing a modified graphene oxide plugging agent, characterized in that, The main raw materials for the sealing agent are: phosphoric acid, alkanolamines, graphene oxide, and acryloyloxyethyltrimethylammonium chloride. The preparation includes the following steps: S1. Add phosphoric acid and alkanolamine to a three-necked flask containing water, purge with nitrogen, stir, and heat in a water bath at 40-60°C for 2-6 hours. After the reaction is complete, separate the water by vacuum distillation to obtain intermediate product A; the molar ratio of phosphoric acid to alkanolamine is (2.8-3.2):

1. S2. Weigh graphene oxide and place it in pure water. Disperse it ultrasonically for 20-40 minutes to obtain a suspension of graphene oxide. Then add intermediate A of the product obtained in step S1 to it. Stir at 20-25℃ and add propyl phosphoric anhydride dropwise. The addition is completed within 1.5 hours. Stir the reaction mixture further overnight. After the reaction is completed, wash with water and dry to obtain intermediate B of the product. S3. Add intermediate B obtained in step S2 to a three-necked flask containing water, then add acryloyloxyethyltrimethylammonium chloride, then add ferric chloride solution, stir and react at 20-25℃ for 12-16h, wash with water and dry after the reaction to obtain the modified graphene oxide blocking agent.

2. The preparation method of the modified graphene oxide blocking agent according to claim 1, characterized in that, In step S1, the alcohol amine is one of ethanolamine, isopropanolamine, or 2-amino-2-methyl-1-propanol.

3. The preparation method of the modified graphene oxide blocking agent according to claim 1, characterized in that, In step S2, the mass ratio of intermediate product A to graphene oxide is (5-6):

1.

4. The preparation method of the modified graphene oxide blocking agent according to claim 1, characterized in that, In step S3, the mass ratio of intermediate product B to acryloyloxyethyltrimethylammonium chloride is 1:(18-22).

5. A plugging agent prepared by the method of any one of claims 1-4 for preparing the modified graphene oxide plugging agent.

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