High-temperature-resistant solid-free drilling fluid and preparation method thereof

Abstract

The invention provides a high-temperature-resistant solid-free drilling fluid and a preparation method thereof, and belongs to the technical field of petroleum engineering drilling fluids. The high-temperature-resistant solid-free drilling fluid comprises the following components: a high-temperature-resistant tackifier, a high-temperature-resistant filtrate reducer, a high-temperature stabilizer, a nano plugging agent, a pH regulator, a weighting agent and water, wherein the high-temperature-resistant tackifier is a copolymer which is prepared from the following raw materials: allyl glyceryl ether, 2-acrylamide-2-methylpropanesulfonic acid and N-vinyl pyrrolidone; the high temperature resistant filtrate reducer is a 2-acrylamide-2-methylpropanesulfonic acid autopolymer or a copolymer of the 2-acrylamide-2-methylpropanesulfonic acid autopolymer and other acrylamide monomers. The system is good in rheological property, temperature resistance and filtrate loss reduction performance and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering drilling fluids, and in particular relates to a high-temperature resistant solid-phase-free drilling fluid and a preparation method thereof. Background Art

[0002] In traditional water-based and oil-based drilling fluids, barite, iron ore, calcium carbonate and other materials are often used to increase the weight of the system, resulting in a large solid content in the drilling fluid system, which is very harmful to reservoirs, especially sensitive reservoirs. The increase in solid content will also lead to poor lubrication performance of the drilling fluid system, difficulty in regulating rheological properties, and reduce drilling rates. Therefore, reducing the use of solids is of great significance to reservoir protection.

[0003] Solid-free drilling fluid generally refers to a type of drilling fluid system without a clay phase in the drilling fluid system. The density of this type of system can be adjusted by adding salts. Commonly used salts include sodium chloride, sodium formate, potassium chloride, potassium formate, etc. A certain amount of viscosity enhancer, filtration reducer, high temperature protective agent, plugging agent, etc. must also be added. Since it does not contain a solid phase, this type of drilling fluid system can solve the above problems very well.

[0004] In the prior art, patent CN116265561A discloses a solid-free drilling fluid system, which uses Chevron Phillips's viscosity enhancer HE300, Sinopec Engineering Technology Research Institute's high temperature and calcium resistance fluid loss reducer, flow pattern regulator, etc. as treatment agents. The system has a temperature resistance of 180°C and a salt resistance of 15,000 mg / L, but the imported HE300 has the disadvantage of being more expensive. Patent CN105131915A discloses a solid-free drilling fluid system, which uses polyanionic cellulose as a fluid loss reducer and Dristemp as a viscosity enhancer, with a maximum density of 2.3 g / cm 3 , temperature resistance up to 200℃, the system has strong stability, inhibition and lubricity at high temperature, but similar to patent CN116265561A, the system uses imported viscosity enhancers, and the system cost is an obstacle to its large-scale promotion. In order to solve the shortcomings of the existing solid-free system that it is difficult to balance the temperature resistance and cost, it is urgent to carry out research on the construction of a solid-free drilling fluid system with domestic products. Summary of the invention

[0005] In view of the problem that the existing solid-free drilling fluid has insufficient temperature resistance, the present invention provides a new high-temperature resistant solid-free drilling fluid and a preparation method thereof. The solid-free drilling fluid system of the present invention has a temperature resistance of up to 200°C, good temperature resistance, and good application prospects.

[0006] One of the purposes of the present invention is to provide a high temperature resistant solid-free drilling fluid.

[0007] The second object of the present invention is to provide a method for preparing the high temperature resistant solid-free drilling fluid.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, the present invention provides a high temperature resistant solid-free drilling fluid, the high temperature resistant solid-free drilling fluid comprising the following components: a high temperature resistant viscosity enhancer, a high temperature resistant fluid loss reducer, a high temperature stabilizer, a nano plugging agent, a pH regulator, a weighting agent and water;

[0010] The high temperature resistant viscosity enhancer is a copolymer made of allyl glyceryl ether, 2-acrylamide-2-methylpropane sulfonic acid and N-vinyl pyrrolidone;

[0011] The high temperature resistant fluid loss reducer is a 2-acrylamide-2-methylpropane sulfonic acid self-polymer, or a copolymer with other acrylamide monomers.

[0012] In some embodiments, based on 100 mL of water, the amount of high temperature resistant viscosity enhancer added is 0.5-2 g, the amount of high temperature resistant fluid loss reducer added is 1.5-3 g, the amount of high temperature stabilizer added is 0.3-1.5 g, the amount of nano plugging agent added is 1-3 g, and the amount of pH regulator added is 0.1-0.5 g; the density of the high temperature resistant solid-free drilling fluid is 1.05-1.50 g / cm 3 . Determine the amount of weighting agent to be added based on density requirements.

[0013] High temperature resistant viscosity enhancer:

[0014] In the present invention, the high temperature resistant tackifier is a copolymer with allyl glyceryl ether, 2-acrylamide-2-methylpropane sulfonic acid and N-vinyl pyrrolidone as raw materials; the molecular weight of the high temperature resistant tackifier is preferably 5 million to 15 million.

[0015] The copolymer is self-developed by the inventor, and the preparation method of the high temperature resistant tackifier is as follows:

[0016] (1) dissolving 1-3 parts by weight of N-vinyl pyrrolidone, 5-7 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, and 1-4 parts by weight of allyl glyceryl ether in deionized water to prepare a 20%-50% aqueous solution, and adjusting the pH to 6-8 with sodium hydroxide;

[0017] (2) based on the mass of the three monomers in step (1) being 100%, adding 0.01%-0.5% of an oxidizing agent, 0.01%-0.5% of a reducing agent, 0.01%-0.3% of azobisisobutylamidine hydrochloride, and 0.005%-0.05% of a cross-linking agent, stirring to dissolve; wherein the oxidizing agent is one or more selected from ammonium persulfate, potassium persulfate, hydrogen peroxide, and sodium persulfate; the reducing agent is one or more selected from sodium bisulfite, ammonium ferrous sulfate, and urea; and the cross-linking agent is one or more selected from N'N-methylenebisacrylamide and divinylbenzene;

[0018] (3) Pass high-purity nitrogen for 30 minutes, set the initial reaction temperature to 5-15°C, and after 30 minutes of reaction, adjust the temperature to 30-50°C;

[0019] (4) After reacting for 2 h to 10 h, a high temperature resistant tackifier with a solid content of 20% to 45% is obtained, and the product is dried and crushed to obtain a high temperature resistant tackifier powder.

[0020] The added amount of the high temperature resistant viscosity increasing agent is, for example, 0.5 g, 1 g, 1.5 g, 2 g, etc., but is not limited thereto.

[0021] The high temperature resistant viscosity increasing agent has the function of increasing the viscosity and dynamic shear force of the solid-free drilling fluid system.

[0022] High temperature resistant fluid loss reducer:

[0023] In the present invention, the high temperature resistant fluid loss reducer is a 2-acrylamide-2-methylpropanesulfonic acid self-polymer, or a copolymer with other acrylamide monomers, and other acrylamide monomers include one or more of methacrylamide, N-isopropylacrylamide, N'N-methylenebisacrylamide, and N'N-dimethylacrylamide.

[0024] The added amount of the high temperature resistant fluid loss reducer is, for example, 1.5 g, 2 g, 2.5 g, 3 g, etc., but is not limited thereto.

[0025] High temperature fluid loss reducer has the effect of reducing the fluid loss of drilling fluid.

[0026] High temperature stabilizer:

[0027] In some embodiments, the high temperature stabilizer is sodium sulfite.

[0028] The added amount of the high temperature stabilizer is, for example, 0.3 g, 0.5 g, 0.6 g, 0.8 g, 1 g, 1.2 g, 1.5 g, etc., but is not limited thereto.

[0029] Nano plugging agent:

[0030] In some embodiments, the nano plugging agent is a polymer nanosphere. Preferably, the polymer nanosphere is a methyl methacrylate polymer microsphere with a particle size of 20-800 nm.

[0031] The amount of the nano plugging agent added is, for example, 1 g, 1.5 g, 2 g, 2.5 g, 3 g, etc., but is not limited thereto.

[0032] Nano plugging agents can plug micro-nano pores and cracks, reduce filtration and improve mud cake quality.

[0033] pH Adjuster:

[0034] In some embodiments, the pH adjuster is selected from at least one of sodium hydroxide and sodium carbonate.

[0035] The amount of the pH adjuster added is, for example, 0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g, etc., but is not limited thereto.

[0036] Weighting agent:

[0037] In some embodiments, the weighting agent is selected from organic salts and / or inorganic salts. Preferably, the inorganic salt is selected from potassium chloride and / or sodium chloride. Preferably, the organic salt is selected from at least one of sodium formate and potassium formate.

[0038] In the solid-free drilling fluid system of the present invention, the cost of the drilling fluid system is greatly reduced by adopting the independently developed high-temperature resistant viscosity enhancer. At the same time, the rheological properties of the drilling fluid system are equivalent to those of the drilling fluid system using expensive materials. Compared with the existing similar foreign products, the independently developed high-temperature resistant viscosity enhancer product has a 40% increase in viscosity at the same dosage and has equivalent temperature resistance. The high-temperature resistant fluid loss reducer and the viscosity enhancer complement each other, effectively reducing the filtration loss of the solid-free drilling fluid system and increasing its temperature resistance stability.

[0039] In a second aspect, the present invention provides a method for preparing the above-mentioned high temperature resistant solid-free drilling fluid, comprising the following steps:

[0040] Add high temperature resistant viscosity enhancer, high temperature resistant fluid loss reducer, high temperature stabilizer, nano plugging agent, pH adjuster and weighting agent into water and mix well.

[0041] In some embodiments, the preparation method comprises: mixing the high temperature resistant viscosity enhancer with water, and then sequentially mixing with the high temperature resistant fluid loss reducer, pH adjuster, high temperature stabilizer, nano plugging agent and weighting agent.

[0042] In a specific embodiment, the preparation method comprises:

[0043] (1) Preparation of high temperature resistant thickener solution: set the stirring speed to 4000-12000 r / min, slowly add 0.5-2 g of high temperature resistant thickener to 100 mL of water, and continue stirring for 5-20 minutes to fully dissolve it;

[0044] (2) Set the stirring speed to 4000-12000 r / min, slowly add 1.5-3 g of high temperature resistant fluid loss reducer, and continue stirring for 5-20 minutes to fully dissolve it;

[0045] (3) Set the stirring speed to 4000-12000 r / min, add 0.1-0.5 g of pH adjuster, and continue stirring for 2-5 minutes to fully dissolve it;

[0046] (4) Set the stirring speed to 4000-12000 r / min, add 0.3-1.5 g of high temperature stabilizer, and continue stirring for 2-5 minutes to fully dissolve it;

[0047] (5) Set the stirring speed to 4000-12000 r / min, add 1-3 g of nano plugging agent, and continue stirring for 3-7 minutes to fully dissolve it;

[0048] (6) Set the stirring speed to 4000-12000 r / min, add a certain amount of weighting agent according to the designed density of the drilling fluid, and continue stirring for 10-20 minutes to fully dissolve it;

[0049] (7) After the above components in the drilling fluid are dissolved or dispersed uniformly, a high temperature resistant solid-free drilling fluid is obtained.

[0050] Beneficial effects:

[0051] (1) The solid-free drilling fluid system of the present invention contains no harmful solid phase during the preparation process, which causes little damage to the oil and gas reservoirs and is beneficial to increasing the production of oil and gas wells.

[0052] (2) The solid-free drilling fluid system of the present invention has good rheological properties and temperature resistance, and can meet the needs of on-site construction in oil and gas fields.

[0053] (3) The solid-free drilling fluid system of the present invention has low filtration loss and thin mud cake, which can effectively protect the reservoir and improve the stability of the wellbore.

[0054] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0056] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0057] N-vinylpyrrolidone was from Shandong Xinghai Chemical Co., Ltd.;

[0058] 2-Acrylamide-2-methylpropanesulfonic acid was from Jiangsu Shenglun Chemical Technology Co., Ltd.;

[0059] Allyl glyceryl ether was from Shanghai Demao Chemical Co., Ltd.;

[0060] N'N-methylenebisacrylamide comes from Qingdao Huawei Ruisi New Materials Co., Ltd.

[0061] Preparation Example 1 Preparation of high temperature resistant viscosity enhancer

[0062] (1) 5 g of N-vinyl pyrrolidone, 35 g of 2-acrylamide-2-methylpropanesulfonic acid, and 10 g of allyl glyceryl ether were dissolved in deionized water cooled to 4° C. to prepare a 35% aqueous solution, and sodium hydroxide was added to adjust the pH to neutral;

[0063] (2) adding 0.05 g of ammonium persulfate, 0.05 g of sodium bisulfite, and 0.15 g of azobisisobutylamidine hydrochloride, stirring to dissolve, and then adding 0.003 g of N'N-methylenebisacrylamide, stirring to dissolve;

[0064] (3) Pass high-purity nitrogen for 30 minutes, set the temperature to 8°C, and after reacting for 30 minutes, raise the temperature to 30°C;

[0065] (4) After reacting for 10 hours, a high temperature resistant tackifier block is obtained, and the block is dried and crushed to obtain a high temperature resistant tackifier powder.

[0066] Preparation Example 2 Preparation of high temperature resistant viscosity enhancer

[0067] (1) 3 g of N-vinyl pyrrolidone, 15 g of 2-acrylamide-2-methylpropanesulfonic acid, and 12 g of allyl glyceryl ether were dissolved in deionized water cooled to 4° C. to prepare a 20% aqueous solution, and sodium hydroxide was added to adjust the pH to neutral;

[0068] (2) adding 0.15 g of ammonium persulfate, 0.15 g of sodium bisulfite, and 0.003 g of azobisisobutylamidine hydrochloride, stirring to dissolve, and then adding 0.0015 g of N'N-methylenebisacrylamide, stirring to dissolve;

[0069] (3) Pass high-purity nitrogen for 30 minutes, set the temperature to 10°C, and after reacting for 30 minutes, raise the temperature to 50°C;

[0070] (4) After reacting for 6 hours, a high temperature resistant viscosity increasing fluid loss reducing agent block is obtained, and the block is dried and crushed to obtain a high temperature resistant viscosity increasing fluid loss reducing agent powder.

[0071] Preparation Example 3 Preparation of high temperature resistant viscosity enhancer

[0072] (1) 2 g of N-vinyl pyrrolidone, 12 g of 2-acrylamide-2-methylpropanesulfonic acid, and 8 g of allyl glyceryl ether were dissolved in deionized water cooled to 4° C. to prepare a 50% aqueous solution, and sodium hydroxide was added to adjust the pH to neutral;

[0073] (2) Add 0.0022 g of ammonium persulfate, 0.0022 g of sodium bisulfite, and 0.0066 g of azobisisobutylamidine hydrochloride, stir to dissolve, and then add 0.011 g of N'N-methylenebisacrylamide and stir to dissolve;

[0074] (3) Pass high-purity nitrogen for 30 minutes, set the temperature to 5°C, and after reacting for 30 minutes, raise the temperature to 40°C;

[0075] (4) After reacting for 2 hours, a high temperature resistant viscosity increasing fluid loss reducing agent block is obtained, and the block is dried and crushed to obtain a high temperature resistant viscosity increasing fluid loss reducing agent powder.

[0076] Example 1

[0077] (1) Take 400 mL of water and add it to a high-stirring cup. Stir at a speed of 10,000 r / min. Add 4 g of high-temperature resistant viscosity enhancer while stirring. Continue stirring for 15 minutes.

[0078] (2) 8 g of high temperature resistant fluid loss reducer HFL (2-acrylamide-2-methylpropanesulfonic acid fluid loss reducer, purchased from Hubei Hanke New Technology Co., Ltd.) was added while stirring, and stirring was continued for 15 minutes.

[0079] (3) Add 1 g of pH adjuster sodium hydroxide while stirring, and continue stirring for 5 minutes.

[0080] (4) Add 2 g of high temperature stabilizer sodium sulfite while stirring and continue stirring for 5 minutes.

[0081] (5) Add 6 g of nano plugging agent methyl methacrylate polymer microspheres with a particle size D50 of 600 nm (purchased from the Chemical Company of Great Wall Drilling Engineering Co., Ltd.) while stirring, and continue stirring for 5 minutes.

[0082] (6) Add 135 g of sodium formate while stirring and continue stirring for 20 minutes.

[0083] (7) After the above components in the drilling fluid are dissolved or dispersed uniformly, a solid-free drilling fluid system 1 is obtained.

[0084] Example 2

[0085] A solid-free drilling fluid was prepared according to the method of Example 1, except that the amount of the high temperature resistant viscosity enhancer was adjusted to 6 g, to obtain a solid-free drilling fluid system 2.

[0086] Example 3

[0087] A solid-free drilling fluid was prepared according to the method of Example 1, except that the amount of high temperature resistant fluid loss reducer added was adjusted to 6 g, to obtain a solid-free drilling fluid system 3.

[0088] Example 4

[0089] A solid-free drilling fluid was prepared according to the method of Example 1, except that the amount of the nano plugging agent added was adjusted to 8 g, to obtain a solid-free drilling fluid system 4.

[0090] Example 5

[0091] The solid-free drilling fluid was prepared according to the method of Example 1, except that the amount of sodium formate added was adjusted to change the density of the solid-free drilling fluid sample from 1.1 g / cm 3 Adjust to a density of 1.5 g / cm 3 , and obtain a solid-free drilling fluid system 5.

[0092] Comparative Example 1

[0093] A solid-free drilling fluid was prepared according to the method of Example 1, except that the high temperature resistant viscosity enhancer of Example 1 was replaced by high temperature resistant viscosity enhancer HE300 (Chevron Phillips Chemical Co., Ltd., brand name vinyl polymer HE300).

[0094] Comparative Example 2

[0095] The solid-free drilling fluid was prepared according to the method of Example 1, except that the high temperature resistant fluid loss reducer HFL in Example 1 was replaced by the same amount of PAC-LV (polyanionic cellulose, Renqiu Deli Petroleum Additives Co., Ltd.).

[0096] The solid-free drilling fluid systems prepared in Examples 1-5 and Comparative Examples 1-2 were respectively placed in an aging tank, heated in a high-temperature roller furnace at 200°C for 16 hours, taken out, and stirred at a speed of 10000 r / min for 10 minutes. According to GB / T 16783.1-2014 "Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 1: Water-based Drilling Fluids", the apparent viscosity, plastic viscosity, dynamic shear force, and medium pressure filtration loss (FL) of each sample were measured. API ) and high temperature and high pressure fluid loss (FL HTHP), and the test results are shown in the table below.

[0097] Table 1 Performance test results of solid-free drilling fluid system

[0098]

[0099]

[0100] Table 1 shows the performance of different samples of the solid-free drilling fluid system. From the performance results of the embodiments and comparative examples, it can be seen that the system has good rheological properties, temperature resistance, and filtration loss reduction performance. Compared with Example 1, the viscosity and dynamic shear force of Comparative Example 1 are reduced to a certain extent, and the room temperature medium pressure filtration loss and high temperature and high pressure filtration loss are increased to a certain extent. More importantly, the cost of the high temperature resistant viscosity enhancer of the present invention is less than 50% of the high temperature resistant viscosity enhancer HE300 used in Comparative Example 1, which greatly reduces the cost of the solid-free drilling fluid system. The room temperature medium pressure filtration loss and high temperature and high pressure filtration loss of Comparative Example 2 are significantly greater than those of Example 1, indicating that the solid-free drilling fluid system of the present invention has a good filtration loss reduction effect.

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A high temperature resistant solid-free drilling fluid, characterized in that: The high temperature resistant solid-free drilling fluid comprises the following components: a high temperature resistant viscosity enhancer, a high temperature resistant fluid loss reducer, a high temperature stabilizer, a nano plugging agent, a pH regulator, a weighting agent and water; The high temperature resistant viscosity enhancer is a copolymer made of allyl glyceryl ether, 2-acrylamide-2-methylpropane sulfonic acid and N-vinyl pyrrolidone; The high temperature resistant fluid loss reducer is a 2-acrylamide-2-methylpropane sulfonic acid self-polymer, or a copolymer with other acrylamide monomers.

2. The high temperature resistant solid-free drilling fluid according to claim 1, characterized in that: Based on 100 mL of water, the amount of high temperature resistant viscosity enhancer added is 0.5-2 g, the amount of high temperature resistant filtrate reducer added is 1.5-3 g, the amount of high temperature stabilizer added is 0.3-1.5 g, the amount of nano plugging agent added is 1-3 g, and the amount of pH regulator added is 0.1-0.5 g; the density of the high temperature resistant solid-free drilling fluid is 1.05-1.50 g / cm 3 .

3. The high temperature resistant solid-free drilling fluid according to claim 1 or 2, characterized in that: The molecular weight of the high temperature resistant tackifier is 5 million to 15 million; The preparation method of the high temperature resistant tackifier is as follows: (1) dissolving 1-3 parts by weight of N-vinyl pyrrolidone, 5-7 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, and 1-4 parts by weight of allyl glyceryl ether in deionized water to prepare a 20%-50% aqueous solution, and adjusting the pH to 6-8 with sodium hydroxide; (2) based on the mass of the three monomers in step (1) being 100%, adding 0.01%-0.5% of an oxidizing agent, 0.01%-0.5% of a reducing agent, 0.01%-0.3% of azobisisobutylamidine hydrochloride, and 0.005%-0.05% of a cross-linking agent, stirring to dissolve; wherein the oxidizing agent is one or more selected from ammonium persulfate, potassium persulfate, hydrogen peroxide, and sodium persulfate; the reducing agent is one or more selected from sodium bisulfite, ammonium ferrous sulfate, and urea; and the cross-linking agent is one or more selected from N'N-methylenebisacrylamide and divinylbenzene; (3) Pass high-purity nitrogen for 30 minutes, set the initial reaction temperature to 5-15°C, and after 30 minutes of reaction, adjust the temperature to 30-50°C; (4) After reacting for 2 h to 10 h, a high temperature resistant tackifier with a solid content of 20% to 45% is obtained, and the product is dried and crushed to obtain a high temperature resistant tackifier powder.

4. The high temperature resistant solid-free drilling fluid according to claim 1 or 2, characterized in that: The high temperature stabilizer is sodium sulfite.

5. The high temperature resistant solid-free drilling fluid according to claim 1 or 2, characterized in that: The nano plugging agent is polymer nano microspheres; Preferably, the polymer nanospheres are methyl methacrylate polymer microspheres with a particle size of 20-800 nm.

6. The high temperature resistant solid-free drilling fluid according to claim 1 or 2, characterized in that: The pH regulator is selected from at least one of sodium hydroxide and sodium carbonate.

7. The high temperature resistant solid-free drilling fluid according to claim 1 or 2, characterized in that: The weighting agent is selected from organic salts and / or inorganic salts; Preferably, the inorganic salt is selected from potassium chloride and / or sodium chloride; Preferably, the organic salt is selected from at least one of sodium formate and potassium formate.

8. A method for preparing a high temperature resistant solid-free drilling fluid according to any one of claims 1 to 7, characterized in that: The following steps are involved: Add high temperature resistant viscosity enhancer, high temperature resistant fluid loss reducer, high temperature stabilizer, nano plugging agent, pH adjuster and weighting agent into water and mix well.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises: mixing the high temperature resistant viscosity enhancer with water, and then sequentially mixing with the high temperature resistant fluid loss reducer, pH regulator, high temperature stabilizer, nano plugging agent and weighting agent.

10. The preparation method according to claim 8, characterized in that: The following steps are involved: (1) Preparation of high temperature resistant thickener solution: set the stirring speed to 4000-12000 r / min, slowly add 0.5-2 g of high temperature resistant thickener to 100 mL of water, and continue stirring for 5-20 minutes to fully dissolve it; (2) Set the stirring speed to 4000-12000 r / min, slowly add 1.5-3 g of high temperature resistant fluid loss reducer, and continue stirring for 5-20 minutes to fully dissolve it; (3) Set the stirring speed to 4000-12000 r / min, add 0.1-0.5 g of pH adjuster, and continue stirring for 2-5 minutes to fully dissolve it; (4) Set the stirring speed to 4000-12000 r / min, add 0.3-1.5 g of high temperature stabilizer, and continue stirring for 2-5 minutes to fully dissolve it; (5) Set the stirring speed to 4000-12000 r / min, add 1-3 g of nano plugging agent, and continue stirring for 3-7 minutes to fully dissolve it; (6) Set the stirring speed to 4000-12000 r / min, add a certain amount of weighting agent according to the designed density of the drilling fluid, and continue stirring for 10-20 minutes to fully dissolve it; (7) After the above components in the drilling fluid are dissolved or dispersed uniformly, a high temperature resistant solid-free drilling fluid is obtained.

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