High temperature resistant drilling fluid and its application

Abstract

The application provides an anti-high-temperature drilling fluid and application thereof, and the anti-high-temperature drilling fluid is prepared from the following components in parts by weight: 100 parts of a combination of water and base paste, 0.3-0.5 parts of an alkaline substance, 2-4 parts of an anti-high-temperature viscosity reducer, 3.2-4.0 parts of an anti-high-temperature fluid loss additive, 3.8-4.2 parts of KFT, 1.8-2.2 parts of SMP-2, 4-5 parts of lignite resin, 3.8-4.2 parts of HPAN-NH4, 6-7 parts of monovalent cation inorganic substance, 4-5 parts of white pitch, 5-7 parts of a sodium salt type inhibitor, 1.5-2 parts of an anti-high-temperature lubricant, 0.5-0.7 parts of an oxygen scavenger, 3-5 parts of calcium carbonate or calcium oxide; in the 100 parts of the combination of water and base paste, the base paste accounts for 20-30 parts. The anti-high-temperature drilling fluid of the application still has good rheological property and fluid loss amount at 200 DEG C, and solves the problem of thickening failure of the drilling fluid at high temperature.

Description

Technical Field

[0001] This invention relates to a drilling fluid for oil extraction, and more particularly to a high-temperature resistant drilling fluid and its application, belonging to the field of oilfield chemistry in the petroleum industry. Background Technology

[0002] As oil and gas drilling depths gradually increase from shallow to deep, oil exploration becomes increasingly challenging, especially for deep and ultra-deep wells where bottom-hole temperatures are high and formation pressures are high. This necessitates drilling fluids with excellent stability and rheological properties under high-temperature and high-density conditions. However, ordinary drilling fluids degrade or denature under high-temperature and high-density conditions, leading to incompetence and deterioration of the drilling fluid system's rheological properties, which can result in stuck pipe and wellbore instability.

[0003] Currently, there are three technical methods to address the rheological properties of high-temperature, high-density water-based drilling fluids: First, adding synthetic polymer viscosity reducers, such as tannic acid, sulfonated tannin, and copolymers like XY-27, to the drilling fluid system. However, these products suffer from poor resistance to ultra-high temperatures and salt (temperature resistance below 200℃ and salt resistance less than 10%). Second, adding high-temperature filtration reducers to decrease filtration loss and improve filter cake quality to maintain wellbore stability. However, most filtration reducers fail above 180℃. Third, adding lubricants to increase the steric hindrance of solid particles in the drilling fluid system, thereby reducing friction. However, most lubricants also suffer from poor temperature resistance and high cost. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a high-temperature resistant drilling fluid. By synergistically combining a high-temperature resistant filtration loss reducer, a high-temperature resistant viscosity reducer, and a high-temperature resistant lubricant, the problem of thickening and failure of drilling fluid at high temperatures is solved, resulting in a drilling fluid that still exhibits good rheological properties and filtration loss reduction effects at 200°C.

[0005] To achieve the above objectives, the present invention provides a high-temperature resistant drilling fluid, wherein the raw materials of the high-temperature resistant drilling fluid are composed of the following components in parts by weight:

[0006] The mixture consists of 100 parts water and base slurry, 0.3-0.5 parts alkaline substances, 2-4 parts high-temperature viscosity reducer, 3.2-4.0 parts high-temperature filtration loss reducer, 3.8-4.2 parts KFT, 1.8-2.2 parts SMP-2, 4-5 parts lignite resin, 3.8-4.2 parts HPAN-NH4, 6-7 parts monovalent cationic inorganic substances, 4-5 parts white asphalt, 5-7 parts sodium salt inhibitor, 1.5-2 parts high-temperature lubricant, 0.5-0.7 parts oxygen scavenger, and 3-5 parts calcium carbonate or calcium oxide.

[0007] In this mixture of 100 parts water and base slurry, the base slurry comprises 20-30 parts. According to a specific embodiment of the present invention, preferably, the density of this high-temperature resistant drilling fluid is 2.5 g / cm³. 3 .

[0008] In the above-mentioned high-temperature resistant drilling fluid, preferably, the density regulator of the high-temperature resistant drilling fluid is barite.

[0009] In the above-mentioned high-temperature resistant drilling fluid, the role of alkaline substances is to adjust the pH of the drilling fluid, so that the treatment agents in the drilling fluid can play a full role. NaOH or KOH is preferred.

[0010] In the above-mentioned high-temperature resistant drilling fluid, preferably, the base slurry is a fresh water-based slurry prepared by bentonite and anhydrous sodium carbonate; the concentration of the base slurry itself is 1%-1.5%, and the mass ratio of bentonite to anhydrous sodium carbonate is 20:1.

[0011] In the above-mentioned high-temperature resistant drilling fluid, preferably, the high-temperature filtration reduction agent (UHTP-1) is a polymer formed by addition polymerization of four monomers: 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, N,N-dimethylacrylamide, and N-vinylpyrrolidone in a molar ratio of (5-6):2:2:(1-2), and the molar ratio is preferably 5:2:2:1, 6:2:2:2, or 6:2:2:1.

[0012] In the above-mentioned high-temperature resistant drilling fluid, preferably, the addition polymerization temperature for preparing the high-temperature resistant filtration loss reducer (UHTP-1) is 60°C and the time is 5.5h-6.5h, preferably 6h; nitrogen gas needs to be introduced during the first 0.5h of the reaction time. The addition polymer has good high-temperature resistance and filtration loss reduction effect. The single agent of the high-temperature resistant filtration loss reducer (UHTP-1) can withstand a maximum temperature of 240°C, and its temperature resistance and filtration loss reduction effect is far superior to similar filtration loss reduction polymers.

[0013] In the above-mentioned high-temperature resistant drilling fluid, preferably, the high-temperature resistant viscosity reducer (UHTP-2) is an amphoteric chelate viscosity reducer (low molecular weight viscous polymer) formed by the addition polymerization of three monomers, DMDAAC, sodium 4-styrene sulfonate, and 2-acrylamido-2-methylpropanesulfonic acid, in a molar ratio of (2-3):(1-2):(1-2); preferably, the molar ratio of the three monomers is 2:1:1, 3:1:1, 2:1:2, or 2:2:1.

[0014] In the aforementioned high-temperature resistant drilling fluid, preferably, the addition polymerization temperature for preparing the high-temperature resistant viscosity reducer (UHTP-2) is 70°C, and the time is 2.5-3 hours, preferably 3 hours. The high-temperature resistant viscosity reducer (UHTP-2) can effectively regulate the rheological properties of the drilling fluid in the high-temperature resistant system.

[0015] In the above-mentioned high-temperature resistant drilling fluid, preferably, the KFT (high-temperature resistant and salt-resistant fluid loss reducing agent for drilling fluid) is a treatment agent that is widely applicable to freshwater and saltwater drilling fluids and has anti-collapse, viscosity reduction, and fluid loss reduction properties. This product requires a small dosage and has low cost, which can significantly improve drilling efficiency.

[0016] In the above-mentioned high-temperature resistant drilling fluid, preferably, the sulfonated phenolic resin (SMP-2) is an anionic water-soluble polyelectrolyte with a molecular weight of about 130-150. It is a temperature- and salt-resistant drilling fluid fluid loss reducer. As a deep well mud treatment agent, it has good properties such as high temperature and high pressure fluid loss reduction, salt resistance, calcium resistance, and reduction of mud cake friction coefficient. It plays an important role in consolidating the well wall, preventing collapse, and preventing stuck.

[0017] In the above-mentioned high-temperature resistant drilling fluid, preferably, lignite resin (SPNH) is a multi-component copolymer drilling fluid filtration reducer composed of nitrohumic acid, sulfomethylphenol resin, etc., and has a viscosity-reducing effect. It also has temperature and salt resistance properties, can reduce the water loss of fresh water, saline water and saline cement slurry, and does not pollute the environment.

[0018] In the above-mentioned high-temperature resistant drilling fluid, HPAN-NH4 is preferably a high-temperature filtration reducer that can change the rheological properties of the drilling fluid, inhibit clay hydration and dispersion, and has salt resistance.

[0019] In the above-mentioned high-temperature resistant drilling fluid, preferably, the monovalent cationic inorganic substance is KCl or NaCl, which has good inhibitory properties.

[0020] In the above-mentioned high-temperature resistant drilling fluid, preferably, the sodium salt inhibitor is Soltex; Soltex is a high-temperature resistant inhibitor that can withstand 200°C and has excellent filtration loss reduction and wall-building performance.

[0021] In the aforementioned high-temperature resistant drilling fluid, preferably, the high-temperature resistant lubricant (HTBL) is prepared by the following steps: 3,4-dihydroxybenzoic acid and n-octadecylamine are polymerized at a molar ratio of (2-2.5):(1-1.5), preferably 2:1, to generate octadecyl dihydroxybenzoamide. This octadecyl dihydroxybenzoamide is then mixed with a solvent oil alcohol at a molar ratio of (1-2):(1-2) at 65-70°C for 3-4 hours, with the mixing time preferably being 3 hours. The high-temperature resistant lubricant (HTBL) is a bonding-type lubricant that can affect the bonding force between clay particles, thereby enhancing the steric hindrance between solid particles in the drilling fluid.

[0022] In the above-mentioned high-temperature resistant drilling fluid, preferably, the deoxygenating agent includes one or more combinations of sodium sulfite, ammonium sulfite, sulfur dioxide and N2H4.

[0023] In the above-mentioned high-temperature resistant drilling fluid, preferably, the calcium carbonate or calcium oxide has a fineness of 1600 mesh.

[0024] The present invention also provides the application of the above-mentioned high-temperature resistant drilling fluid in cementing operations at a temperature environment of 200°C.

[0025] The technical solution of the present invention can bring about the following technical effects:

[0026] (1) The high-temperature drilling fluid system formed by using the high-temperature filtration loss reducer (UHTP-1), high-temperature viscosity reducer (UHTP-2), and high-temperature lubricant (HTBL) of the present invention has good stability and low filtration loss.

[0027] (2) The high-temperature drilling fluid system of the present invention can withstand a high temperature of 200°C, and the viscosity changes before and after aging are stable, and it has good compatibility.

[0028] (3) Compared with other high-temperature resistant drilling fluid systems, the high-temperature resistant drilling fluid system of the present invention does not settle at the bottom after aging, has stable rheological properties, and low filtration loss. The high-temperature resistant drilling fluid system of the present invention can be applied to the drilling site and can basically meet the field drilling needs. Detailed Implementation

[0029] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0030] In a specific embodiment of the present invention, the high-temperature filtration reduction agent (UHTP-1) is a polymer synthesized by addition polymerization of four monomers: 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, N,N-dimethylacrylamide, and N-vinylpyrrolidone in a molar ratio of 6:2:2:1. The addition polymerization of this high-temperature filtration reduction agent (UHTP-1) is carried out at 60°C for 6 hours, with nitrogen gas required for the first 0.5 hours of reaction. The polymer synthesized by addition polymerization exhibits excellent high-temperature resistance and filtration reduction effects. The highest temperature resistance of a single agent of this high-temperature filtration reduction agent (UHTP-1) can reach 240°C, and its temperature resistance and filtration reduction effect is far superior to similar filtration reduction polymers.

[0031] In a specific embodiment of the present invention, the high-temperature viscosity reducer (UHTP-2) is an amphoteric chelate viscosity reducer formed by mixing and stirring three monomers—DMDAAC, sodium 4-styrene sulfonate, and 2-acrylamido-2-methylpropanesulfonic acid—in a molar ratio of 2:1:1. The addition polymerization of this high-temperature viscosity reducer (UHTP-2) is carried out at 70°C for 3 hours, and it can effectively regulate the rheological properties of drilling fluids in a high-temperature system.

[0032] In a specific embodiment of the present invention, the high-temperature resistant lubricant (HTBL) is prepared by the following steps: 3,4-dihydroxybenzoic acid and n-octadecylamine are polymerized at a molar ratio of 2:1 to generate octadecyl dihydroxybenzoamide, which is then mixed with solvent oil alcohol at a molar ratio of 1:1 at 70°C for 3 hours. This high-temperature resistant lubricant (HTBL) is a bonding-type lubricant that can affect the bonding force between clay particles, thereby enhancing the steric hindrance between solid particles in the drilling fluid.

[0033] Example 1

[0034] This embodiment provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps:

[0035] Measure 225mL of water into a high-speed mixing cup using a graduated cylinder, then add 1% base slurry (75g), and stir at high speed for 20 minutes. After hydration for 24 hours, add 1.2g of NaOH to the high-speed mixing cup to adjust the pH, and stir at high speed for 20 minutes to ensure complete dissolution. Then add 6g of high-temperature viscosity reducer (UHTP-2) to the high-speed mixing cup, and stir at high speed for 20 minutes to ensure complete dissolution. Continue to add 9.6g of high-temperature filtration reducer (UHTP-1) to the high-speed mixing cup, and stir at high speed for 20 minutes. Continue to add 4.5g of high-temperature lubricant (HTBL) to the high-speed mixing cup, and stir at high speed for 20 minutes. Then add 12g of KFT, 6g of SMP-2, 15g of SPNH, 12g of HPAN-NH4, 18g of KCl, 12g of white asphalt, and 18g of... Soltex was stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate were added to the high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite was added and stirred at high speed for 30 minutes to dissolve completely.

[0036] Example 2

[0037] This embodiment provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps:

[0038] Measure 225mL of water into a high-speed mixing cup using a graduated cylinder, then add 1% base slurry (75g), and stir at high speed for 20 minutes. After hydration for 24 hours, add 1.2g of NaOH to the high-speed mixing cup to adjust the pH, and stir at high speed for 20 minutes to ensure complete dissolution. Then add 12g of high-temperature viscous reducing agent (UHTP-2) to the high-speed mixing cup, and stir at high speed for 20 minutes to ensure complete dissolution. Continue to add 10.4g of high-temperature filtration reducing agent (UHTP-1) to the high-speed mixing cup, and stir at high speed for 20 minutes. Continue to add 6g of high-temperature lubricant (HTBL) to the high-speed mixing cup, and stir at high speed for 20 minutes. Then add 12g of KFT, 6g of SMP-2, 15g of SPNH, 12g of HPAN-NH4, 18g of KCl, 12g of white asphalt, and 18g of... Soltex was stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate were added to the high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite was added and stirred at high speed for 30 minutes to dissolve completely.

[0039] Example 3

[0040] This embodiment provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps: 225 mL of clean water is measured using a graduated cylinder and poured into a high-speed stirring cup. Then, 1% base slurry (75 g) is added, and the mixture is stirred at high speed for 20 minutes. After hydration for 24 hours, 1.2 g of NaOH is added to the high-speed stirring cup to adjust the pH, and the mixture is stirred at high speed for 20 minutes to ensure complete dissolution. Next, 9 g of high-temperature resistant viscosity reducer (UHTP-2) is added to the high-speed stirring cup, and the mixture is stirred at high speed for 20 minutes to ensure complete dissolution. Then, 10 g of high-temperature resistant filtration reducer (UHTP-1) is added to the high-speed stirring cup, and the mixture is stirred at high speed for 20 minutes. Finally, 5 g of high-temperature resistant lubricant (HTBL) is added to the high-speed stirring cup, and the mixture is stirred at high speed for 20 minutes. Then, 12 g of KFT, 6 g of SMP-2, 15 g of SPNH, and 12 g of... are added sequentially. HPAN-NH4, 18g KCl, 12g white pitch, and 18g Soltex are stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate are added to a high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite is added and stirred at high speed for 30 minutes to dissolve completely.

[0041] Example 4

[0042] This embodiment provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps:

[0043] Measure 225mL of water into a high-speed mixing cup using a graduated cylinder, then add 1% base slurry (75g), and stir at high speed for 20 minutes. After hydration for 24 hours, add 1.2g of NaOH to the high-speed mixing cup to adjust the pH, and stir at high speed for 20 minutes to ensure complete dissolution. Then add 9g of high-temperature viscosity reducer (UHTP-2) to the high-speed mixing cup, and stir at high speed for 20 minutes to ensure complete dissolution. Continue to add 9.6g of high-temperature filtration reducer (UHTP-1) to the high-speed mixing cup, and stir at high speed for 20 minutes. Continue to add 4.5g of high-temperature lubricant (HTBL) to the high-speed mixing cup, and stir at high speed for 20 minutes. Then add 12g of KFT, 6g of SMP-2, 15g of SPNH, 12g of HPAN-NH4, 18g of KCl, 12g of white asphalt, and 18g of... Soltex was stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate were added to the high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite was added and stirred at high speed for 30 minutes to dissolve completely.

[0044] Example 5

[0045] This embodiment provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps:

[0046] Measure 225mL of water into a high-speed stirring cup using a graduated cylinder, then add 1% base slurry (75g), and stir at high speed for 20 minutes. After hydration for 24 hours, add 1.2g of NaOH to the high-speed stirring cup to adjust the pH, and stir at high speed for 20 minutes to ensure complete dissolution. Then add 12g of high-temperature viscosity reducer (UHTP-2) to the high-speed stirring cup, and stir at high speed for 20 minutes to ensure complete dissolution. Continue to add 10g of high-temperature filtration reducer (UHTP-1) to the high-speed stirring cup, and stir at high speed for 20 minutes. Continue to add 4.5g of high-temperature lubricant (HTBL) to the high-speed stirring cup, and stir at high speed for 20 minutes. Then add 12g of KFT, 6g of SMP-2, 15g of SPNH, 12g of HPAN-NH4, and 18g of [other ingredients] in sequence. KCl, 12g white asphalt, and 18g Soltex were stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate were added to a high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite was added and stirred at high speed for 30 minutes to dissolve completely.

[0047] Based on the basic performance requirements and test methods of water-based drilling fluids specified in the national standard for drilling engineering, "Water-based Drilling Fluids" (GB / T 16488-2010), the drilling fluid performance of the five examples was evaluated: the drilling fluids of the five examples were hot-rolled and aged at 200℃ for 16 hours, and then the pH, rheology, and HTHP filtration loss after hot-rolling and aging were measured. The results are shown in Table 1.

[0048] Table 1 Density 2.50 g / cm³ 3 Basic properties of drilling fluid (200℃×16h)

[0049]

[0050]

[0051] As can be seen from the data in Table 1, when 9g of high-temperature viscosity reducer (UHTP-2), 10g of high-temperature filtration reducer (UHTP-1), and 5g of high-temperature lubricant (HTBL) are added to the drilling fluid system and aged at 200℃ for 16h, the drilling fluid exhibits the best rheological properties. The rheological properties are stable before and after aging. Furthermore, the optimal filtration reduction of the drilling fluid after high temperature is 9.6mL, and the filter cake thickness is only 4mm. This indicates that the high-temperature resistant drilling fluid system has good temperature resistance and excellent compatibility.

[0052] To further verify that the drilling fluid system of the present invention is superior to other drilling fluid formulations, the effects of Example 3 of the present invention and the drilling fluid system of Comparative Example 1 with the same amount of drilling fluid were compared.

[0053] Comparative Example 1

[0054] This comparative example provides a density of 2.50 g / cm³. 3 The high-temperature resistant, high-density drilling fluid is prepared through the following steps:

[0055] Measure 225 mL of water into a high-speed stirring cup using a graduated cylinder, then add 1% base slurry (75 g), stir at high speed for 20 minutes, and after hydration for 24 hours, add 1.2 g of NaOH to the high-speed stirring cup to adjust the pH, stir at high speed for 20 minutes to fully dissolve; then add 9 g of viscosity reducer XY-27 to the high-speed stirring cup and stir at high speed for 20 minutes to fully dissolve; continue to add 10 g of high-temperature filtration reducer polydrill to the high-speed stirring cup, stir at high speed for 20 minutes; continue to add 5 g of high-temperature lubricant DEL to the high-speed stirring cup, stir at high speed for 20 minutes; then add the same amounts as in Example 3: 12 g KFT, 6 g SMP-2, 15 g SPNH, 12 g HPAN-NH4, and 18 g... KCl, 12g white asphalt, and 18g Soltex were stirred at high speed for 20 minutes to dissolve completely. 1.8g sodium sulfite and 12g calcium carbonate were added to a high-speed stirring cup and stirred at high speed for 20 minutes to dissolve completely. Finally, 800g barite was added and stirred at high speed for 30 minutes to dissolve completely.

[0056] According to the basic performance requirements and test methods of water-based drilling fluids specified in the national standard for drilling engineering, "Water-based Drilling Fluids" (GB / T 16488-2010), the drilling fluid performance of Example 3 and Comparative Example 1 of this invention was evaluated: the drilling fluids were hot-rolled and aged at 200℃ for 16 hours, and then the pH, rheology, and HTHP filtration loss after hot-rolling and aging were measured. The results are shown in Table 2.

[0057] Table 2. Basic performance effects of drilling fluids with different system formulations (200℃×16h)

[0058]

[0059] After hot rolling aging at 200℃ for 16 hours, the viscosity and shear force of the formulation in Comparative Example 1 changed significantly before and after hot rolling aging, and the high-temperature and high-pressure filtration loss was out of control. However, the high-temperature and high-pressure filtration loss of the formulation in Example 3 of this invention was only 9.6 mL after hot rolling aging, and the rheological properties were stable before and after hot rolling aging. The high-temperature filtration loss reduction effect of the formulation in Example 3 of this invention is far better than that of the formulation in Comparative Example 1.

Claims

1. A high-temperature resistant drilling fluid, wherein, The raw materials for this high-temperature resistant drilling fluid consist of the following components in parts by weight: The mixture consists of 100 parts water and base slurry, 0.3-0.5 parts alkaline substances, 2-4 parts high-temperature viscosity reducer, 3.2-4.0 parts high-temperature filtration loss reducer, 3.8-4.2 parts KFT, 1.8-2.2 parts SMP-2, 4-5 parts lignite resin, 3.8-4.2 parts HPAN-NH4, 6-7 parts monovalent cationic inorganic substances, 4-5 parts white asphalt, 5-7 parts sodium salt inhibitor, 1.5-2 parts high-temperature lubricant, 0.5-0.7 parts oxygen scavenger, 3-5 parts calcium carbonate or calcium oxide, and density regulator. In a mixture of 100 parts water and base slurry, the base slurry accounts for 20-30 parts. The concentration of the base slurry itself is 1%-1.5%; The high-temperature filtration loss reducer is a polymer synthesized by addition polymerization of four monomers: 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, N,N-dimethylacrylamide, and N-vinylpyrrolidone in a molar ratio of (5-6):2:2:(1-2). The high-temperature viscosity reducer is an amphoteric chelate viscosity reducer polymerized from three monomers: DMDAAC, sodium 4-styrene sulfonate, and 2-acrylamido-2-methylpropanesulfonic acid in a molar ratio of (2-3):(1-2):(1-2). The high-temperature resistant lubricant is prepared by the following steps: 3,4-dihydroxybenzoic acid and n-octadecylamine are polymerized in a molar ratio of (2-2.5):(1-1.5) to generate octadecyl dihydroxybenzoamide, which is then mixed with solvent oil alcohol in a molar ratio of (1-2):(1-2) at 65-75 °C.

2. The high-temperature resistant drilling fluid according to claim 1, wherein, The density of this high-temperature resistant drilling fluid is 2.35-2.55 g / cm³. 3 .

3. The high-temperature resistant drilling fluid according to claim 2, wherein, The density regulator for this high-temperature resistant drilling fluid is barite.

4. The high-temperature resistant drilling fluid according to claim 1, wherein, The base slurry is prepared by mixing bentonite and anhydrous sodium carbonate in a mass ratio of 20:

1.

5. The high-temperature resistant drilling fluid according to claim 1, wherein, The addition polymerization of the high-temperature resistant filtration loss reducer is carried out at a temperature of 60°C for 5.5-6.5 hours.

6. The high-temperature resistant drilling fluid according to claim 1, wherein, The addition polymerization of the high-temperature resistant viscosity reducer is carried out at a temperature of 70°C for 2.5-3 hours.

7. The high-temperature resistant drilling fluid according to claim 1, wherein, The oxygen scavenger includes one or more combinations of sodium sulfite, ammonium sulfite, sulfur dioxide, and N2H4.

8. The high-temperature resistant drilling fluid according to claim 1, wherein, The calcium carbonate or calcium oxide has a fineness of 1600 mesh.

9. The application of the high-temperature resistant drilling fluid according to any one of claims 1-8 in drilling operations at a temperature environment of 200°C.

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