Reservoir protectant for oil-based drilling fluids, preparation and oil-based drilling fluid comprising same

Abstract

The application discloses a reservoir protection agent for oil-based drilling fluid, preparation and oil-based drilling fluid containing the same. The reservoir protection agent comprises 100 parts of solvent oil, 10 parts of emulsifier, 20-50 parts of surface modified degradable nanometer micro-meter blocking agent, 10 parts of surface modified acid-soluble nanometer inert particles and 3-5 parts of suspending dispersant. The reservoir protection agent contains acid-soluble and degradable solid-phase particles from nanometer to micro-meter, has high blocking rate for fractures and matrix pores, and the solid-phase particles can be 100% acid-soluble or degradable, so that the solid-phase particle blocking damage of the drilling fluid to the reservoir can be reduced.

Description

Technical Field

[0001] This invention relates to the field of oil drilling fluids, specifically to a reservoir protectant for oil-based drilling fluids, its preparation, and an oil-based drilling fluid containing the same. Background Technology

[0002] For tight fractured reservoirs that are highly water-sensitive and prone to wellbore instability, oil-based drilling fluids can maximally suppress the hydration, dispersion, and expansion of water-sensitive minerals, reducing reservoir damage and minimizing accident complexity, making them the preferred drilling fluid system. However, the only shielding and temporary plugging agent used in oil-based drilling fluids is graded calcium carbonate, which is a single type and cannot effectively plug reservoir fractures and pores, leading to severe solid particle blockage and damage. Furthermore, as... Figure 1 As shown, oil-based drilling fluid filtrate can cause liquid phase trapping damage to the reservoir matrix, with permeability reduction rates exceeding 80%. Therefore, the reservoir protection effect of oil-based drilling fluids cannot meet the requirements of tight fractured reservoirs. Summary of the Invention

[0003] The purpose of this invention is to provide a reservoir protectant for oil-based drilling fluids, its preparation, and an oil-based drilling fluid containing the same.

[0004] The reservoir protectant for oil-based drilling fluids of this invention comprises acid-soluble and biodegradable solid particles ranging from nanometer to micrometer scale. It exhibits a high sealing rate against fractures and matrix pores, and the solid particles are 100% acid-soluble or biodegradable, reducing the damage caused by solid particle blockage in the reservoir by the drilling fluid. This reservoir protectant for oil-based drilling fluids can adjust the rock surface to neutral wettability, reducing liquid phase trapping damage. Therefore, this reservoir protectant for oil-based drilling fluids can address the problem of significant damage to tight fractured reservoirs caused by oil-based drilling fluids. Its preparation process is simple, the product has good performance, maintains the rheological properties of the drilling fluid, reduces filtration loss, and effectively protects oil and gas reservoirs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The present invention provides a reservoir protectant for oil-based drilling fluid, wherein the reservoir protectant comprises, by weight, 100 parts solvent oil, 7-18 parts emulsifier, 20-50 parts surface-modified biodegradable nano-micro plugging agent, 6-17 parts surface-modified acid-soluble nano-inert particles, and 3-5 parts suspension dispersant.

[0007] According to the reservoir protectant of the present invention, preferably, the solvent oil is selected from one or more of coconut oil, cottonseed oil, castor oil, rapeseed oil and vegetable oil modified biodiesel; when it is a combination of two or more, the components are combined in any ratio.

[0008] According to the reservoir protectant of the present invention, preferably, the emulsifier is selected from one or a combination of two or more of alkylolamides, sorbitan fatty acid esters, and higher fatty acid calcium. The emulsifier exhibits excellent reverse emulsification properties, can be used for extended periods in a wide oil-water ratio range of 70:30 to 95:5 and a temperature range of 50°C to 180°C, and demonstrates high emulsification stability and high-temperature stability.

[0009] According to the reservoir protectant of the present invention, preferably, the acid-soluble nano-inert particles in the surface-modified acid-soluble nano-inert particles are selected from one or more combinations of nano-calcium carbonate, nano-manganese tetroxide, nano-chitosan, and nano-cellulose. To improve the dispersibility of the acid-soluble nano-inert particles in oil-based drilling fluids, a treatment agent is usually added to change the inert particles from hydrophilic to hydrophobic due to high surface tension. Preferred treatment agents of the present invention are sodium hexametaphosphate, sodium pyrophosphate, tartaric acid, or sodium dodecylbenzenesulfonate, etc.

[0010] According to the reservoir protectant of the present invention, preferably, the suspending dispersant is selected from one or more of carbon-based surfactants, silicone-based surfactants, perfluorinated surfactants, fluorocarbon surfactants and fluorosilicone surfactants.

[0011] The carbon-based surfactant may be one or two of the following: disodium lauryl succinate, hexadecyltrimethylammonium bromide, dodecyltrialkylammonium bromide, sorbitan monostearate, sorbitan monooleate, 2-dodecyl-N-carboxymethyl-N-hydroxyethylimidazoline, octadecyl dimethyl betaine, and alkylphenol polyoxyethylene ether; the silicone-based surfactant may be one or a combination of two or more of the following: acetylenic glycol organosilicon gemini surfactant, N,N-dihydroxy-3-siloxopyrroline salt, N-hydroxy-N-sulfonic acid hydroxy-3-siloxopyrroline salt, 1,4-di(trimethylammonium)-2-[tris(trimethylsiloxy)]-2-ene oxide, vinyltrialkylsilane compound, and methylvinyldimethylsiloxane; the perfluorinated surfactant may have the molecular formula C3F7O(CFCF3CF2O). n CFCF3CONH(CH2)3NCH3(C2H5)2I, C3F7O(CFCF3CF2O) n CFCOONa, C2F5(OCF2CF) n One or more of OC2F4SO3Na, etc.; the fluorocarbon surfactant can be a fluorohexyl polyoxyethylene ether surfactant, a gemini fluorocarbon surfactant (general formula C... 18 F 34 C 12 H8S2O(C2H4) nO2C4H4), perfluoroalkyl ether alcoholamine salt type fluorocarbon surfactants, fluoroalkyl ether carboxylate potassium salt fluorocarbon surfactants, phosphate ester salt type fluorocarbon surfactants, and polyethylene glycol type nonionic fluorocarbon surfactants, or a combination of two or more thereof; the fluorosilicone surfactant may be a phosphate ester type fluorosilicone surfactant, N-dimethylaminopropyl-N-triethylsilylmethylperfluoroalkyl sulfonamide, or 1,3,5-trimethyl-1,3,5-tris(3′,3′,3′-trifluoropropyl)cyclotrisiloxane. One or more of the following: (D3F), perfluorodecyltetrasiloxane surfactant, 1,3,5-trimethyl-1,3,5-tris(3′,3′,3′-trifluoropropyl)cyclotrisiloxane surfactant, poly(2,2,3,3-tetrafluoropropoxy)propylmethylsiloxane, poly(2,2,3,3,4,4,5,5′-octafluoropentaalkoxy)propylmethylsiloxane, polyfluoroalkoxypropylmethylsiloxane, and poly(2-trifluoroethoxy)propylmethylsiloxane.

[0012] According to the reservoir protectant of the present invention, preferably, the surface-modified degradable nano / micro plugging agent is prepared by the following process:

[0013] 100 parts of biodegradable polyester and 2-8 parts of chain extender are added to the reaction vessel of a blending extruder and heated to 60-75°C. Nitrogen gas is introduced at 0.5-0.7 MPa. The reaction is then carried out at 170-190°C. After the reaction is completed, the reaction vessel is pressurized, and the reactants are extruded and granulated. After the granules are cooled and formed, they are frozen to -10°C to 20°C and ground to nano-micron scale. The nano-micron scale granules are added to an aqueous solution of surfactant to modify the surface of the granules. Then, they are heated to 50-60°C and dried to obtain the surface-modified biodegradable nano-micron blocking agent.

[0014] According to the reservoir protectant of the present invention, preferably, the biodegradable polyester is selected from one or more combinations of polylactic acid, polyhydroxyalkanoates, polypropylene carbonate, polypropylene glutarate, polybutylene succinate, polybutylene adipate, polybutylene adipate copolyester, polyester-polyhydroxyalkanoates, polydioxanone, and furanyl dicarboxylate.

[0015] According to the reservoir protectant of the present invention, preferably, the chain extender is selected from one or more combinations of alcohol chain extenders and amine chain extenders. More preferably, the alcohol chain extender is selected from, but not limited to, one or more combinations of 1,4-butanediol (BDO), 1,6-hexanediol, glycerol, trimethylolpropane, diethylene glycol (DEG), triethylene glycol, neopentyl glycol (NPG), sorbitol, and diethylaminoethanol (DEAE). More preferably, the amine chain extender is selected from, but not limited to, one or more combinations of 4,4'-methylenebis(2-chloroaniline) (MOCA) and liquid MOCA modified with formaldehyde, ethylenediamine (DA), N,N-dihydroxy(diisopropyl)aniline (HPA), and hydroquinone di(β-hydroxyethyl) ether (HQEE).

[0016] According to the reservoir protectant of the present invention, preferably, the mass ratio of the alcohol chain extender to the amine chain extender is 3:1. The solvent of the chain extender may be one or a combination of two or more of the following: trimethylolpropane, dimethyldimethoxysilane, diethyltoluenediamine, dimethylthiotoluenediamine, 2,2-dimethylolbutyric acid, methyl tert-butyl ether, methyl tert-butyl ether, and triethylamine.

[0017] According to the reservoir protectant of the present invention, preferably, the surfactant is selected from one or a mixture of two of carbon-based surfactants, silicone-based surfactants, perfluorinated surfactants, carbon-silicon surfactants, carbon-fluorosurfactants, and fluorosilicon surfactants.

[0018] According to the reservoir protectant of the present invention, preferably, the concentration of the surfactant aqueous solution is 0.5% to 1.5% by mass.

[0019] Another aspect of the present invention provides a method for preparing the above-mentioned reservoir protectant for oil-based drilling fluids, the method comprising the following steps:

[0020] The emulsifier is added to the solvent oil, and then the surface-modified biodegradable nano-micro plugging agent, the surface-modified acid-soluble nano-inert particles, and the suspending dispersant are added in sequence. The mixture is then stirred and reacted to obtain the reservoir protectant.

[0021] In another aspect, the present invention provides an oil-based drilling fluid comprising the above-mentioned reservoir protectant.

[0022] When the reservoir protectant of the present invention is added to oil-based drilling fluid, its ability to plug the core is greatly improved, the filtration loss during dynamic contamination is significantly reduced, and the dynamic permeability recovery value, as in the examples, increases from 53.06% to 89.27% ​​and 90.93%.

[0023] Preferably, in the oil-based drilling fluid, the reservoir protectant has a volumetric mass fraction of 1.5% to 3.5% relative to the oil-based drilling fluid emulsion. As will be understood by those skilled in the art, the continuous phase of the oil-based drilling fluid emulsion is an oil phase, such as white oil; the dispersed phase is an aqueous phase, such as tap water or a salt solution of a certain concentration (e.g., calcium chloride solution).

[0024] The reservoir protectant provided by this invention exhibits outstanding performance, effectively enhancing the shielding and temporary plugging capabilities of drilling fluids on oil and gas reservoirs. It is fully acid-soluble during reservoir acidizing. Even without acidizing, it can self-degrade, achieving unblocking. Furthermore, this reservoir protectant promotes wellbore and borehole stability, increases drilling speed, thereby reducing exploration and development costs, protecting oil and gas reservoirs, and improving recovery rates. Attached Figure Description

[0025] Figure 1 This diagram illustrates how oil-based drilling fluids can also cause liquid phase trapping. Detailed Implementation

[0026] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0027] All numerical specifications in this invention (e.g., temperature, time, concentration, and weight, including ranges for each) are generally approximate values ​​that can be changed (+) or (-) in increments of 0.1 or 1.0. All numerical specifications are to be understood as being preceded by the term "about". Unless otherwise specified, "parts" in this invention refers to parts by mass.

[0028] Example 1

[0029] This embodiment describes the preparation of a reservoir protectant for oil-based drilling fluids, comprising the following processes:

[0030] 1) Preparation of surface-modified biodegradable nano / micro plugging agents:

[0031] 15 parts of 1,4-butanediol (BDO) and 5 parts of N,N-dihydroxy(diisopropyl)aniline were pre-mixed in 20 parts of trimethylolpropane and then mixed with 1000 parts of polylactic acid and polyhydroxy fatty acid ester (mass ratio 60:40). The mixture was placed in the reactor of a micro-twin-screw extruder and heated to 75°C. Nitrogen gas was introduced at 0.5 MPa, and the mixture was then heated to 170°C for further reaction. After the reaction was complete, the reactor of the micro-twin-screw extruder was pressurized, and the reactants were extruded and granulated. After the granules cooled and solidified, they were frozen to -20°C and quickly placed in a ball mill to grind them to a median particle size of 5 micrometers. The nano-micron particles were added to 3 parts of an aqueous solution of 1,4-di(trimethylammonium)-2-[tris(trimethylsiloxy)]-2-ene oxide. The particles were surface-modified at room temperature, then heated to 50°C and dried. The resulting white particles were the surface-modified biodegradable nano-micron blocking agent.

[0032] 2) Preparation of surface-modified acid-soluble inert nanoparticles:

[0033] Nanoscale chitosan was added to an aqueous sodium pyrophosphate solution to modify the surface of the particles, and then dried at 50°C to 60°C to obtain the surface-modified biodegradable nano-micro plugging agent.

[0034] 3) Preparation of reservoir protectants for oil-based drilling fluids:

[0035] Take 10 parts of dehydrated sorbitan fatty acid ester emulsifier and put it into 100 parts of diesel oil. Then add 30 parts of surface-modified biodegradable nano-micro plugging agent, 10 parts of surface-modified acid-soluble nano-inert particles, and 5 parts of N-dimethylaminopropyl-N-triethylsilylmethyl perfluoroalkyl sulfonamide in sequence. Mix and stir to react to obtain a yellowish-brown suspension, which is the reservoir protectant for oil-based drilling fluid.

[0036] Example 2

[0037] This embodiment describes the preparation of a reservoir protectant for oil-based drilling fluids, comprising the following processes:

[0038] 1) Preparation of surface-modified biodegradable nano / micro plugging agents:

[0039] 15 parts of diethylaminoethanol (DEAE) and 5 parts of hydroquinone di(β-hydroxyethyl) ether (HQEE) were pre-mixed with 20 parts of methyl tert-butyl ether. This mixture was then combined with 800 parts of polylactic acid, polyhydroxyalkanoates, and polypropylene carbonate (mass ratio 50:40:10) and placed in the reactor of a micro twin-screw extruder. The mixture was heated to 75°C, purged with nitrogen at 0.6 MPa, and then heated to 190°C for further reaction. After the reaction was complete, the reactor of the micro twin-screw extruder was pressurized, and the reactants were extruded to form granules. After the granules cooled and solidified, they were frozen to -20°C and quickly placed in a ball mill to grind them to a median particle size of 0.7 micrometers. Nano- and micro-sized particles were added to 4 parts of an aqueous solution of 1,4-di(trimethylammonium)-2-[tris(trimethylsiloxy)]-2-ene oxide. The particles were surface modified at room temperature, then heated to 50°C and dried. The resulting white particles were the surface-modified biodegradable nano- and micro-sized blocking agent.

[0040] 2) Preparation of surface-modified acid-soluble inert nanoparticles:

[0041] Nano-manganese tetroxide was added to an aqueous solution of sodium dodecylbenzenesulfonate to modify the surface of the particles, and then dried at 50℃~60℃ to obtain the surface-modified biodegradable nano-micro plugging agent.

[0042] 3) Preparation of reservoir protectants for oil-based drilling fluids:

[0043] Take 10 parts of alkylolamide emulsifier and put it into 100 parts of diesel oil. Then add 50 parts of surface-modified biodegradable nano-micro plugging agent, 10 parts of surface-modified acid-soluble nano-inert particles, and 5 parts of N-hydroxy-N-sulfonic acid hydroxy-3-siloxane pyrroline salt in sequence. The resulting yellow-brown suspension obtained by mixing and stirring is the reservoir protectant for oil-based drilling fluid.

[0044] Product performance testing

[0045] (1) Evaluation of the degradation ability of biodegradable nano-micro plugging agents in reservoir protection agents in standard brine. The degradation temperature was 120℃. The standard brine was prepared by adding 8% composite salt to 100g of distilled water. The formula of the composite salt was: NaCl:CaCl2:MgCl2.6H2O=7:0.6:0.4. The results are shown in Table 1.

[0046] Table 1. Degradability of biodegradable nano-micro plugging agents in reservoir protection agents in standard brine.

[0047]

[0048] As shown in Table 1, the biodegradable nano-micro plugging agent, one of the key solid particles in this invention, degrades slowly before 40 days, which is sufficient to meet the plugging requirements during reservoir drilling in actual well operations. After 40 days, the degradation rate reaches an inflection point, and after 120 days, it is almost completely degraded. By degrading the nano-micro plugging agent, the density of the blockage layer formed by the drilling fluid solid phase in the pore channels can be broken down, reducing the flow resistance of oil and gas resources and achieving the purpose of reservoir protection.

[0049] (2) The reservoir protectant synthesized in Examples 1-2 was used to formulate an oil-based drilling fluid, wherein the reservoir protectant was added at a volume mass fraction of 3% relative to the oil-based drilling fluid emulsion. The oil-based drilling fluid formulated with the reservoir protectant was evaluated for permeability recovery, plugging rate, and degradation rate. The experimental results are shown in Table 2.

[0050] The method for dynamic permeability recovery value performance testing in oil-based drilling fluid systems is in accordance with SYT6540-2002 "Indoor Evaluation Method for Damage to Oil Reservoirs by Drilling Fluid and Completion Fluid".

[0051] Formula 2: 6% emulsifier + 2% organic clay + 3% calcium oxide + 2% liquid filtration reducer + 3% oil-based drilling fluid reservoir protectant + barite (weighted to a density of 2.0 g / cm³) 3 ) and combined with Formula 1: 6% emulsifier + 2% organic clay + 3% calcium oxide + 2% liquid filtration reducer + barite (weighted to a density of 2.0 g / cm³) 3 A comparative experiment was conducted on the dynamic permeability recovery value. The oil-water ratio was 95:5. The continuous phase was No. 5 white oil, and the dispersed phase was a 20% calcium chloride (CaCl2) solution. The emulsifier was an organic acid ester surfactant, i.e., with the general formula R1-(CH2)n(COO)m(CH2)n-R2, where R1 and R2 are C15-C21 alkanes or monoolefins, n is 1-3, and m is 1-4. Its function is to significantly reduce the interfacial tension between the oil and water phases, form a strong interfacial film, and have strong emulsifying ability, which is beneficial to the stability of the suspension. Organic clay: The quaternized product of montmorillonite was selected, i.e., montmorillonite-[C 12 H 25 [N+-(CH3)3]. Organic soil can form a strong spatial network structure, improving adhesion and shear, and enhancing rheological properties. Calcium oxide (CaO): provides reserve alkalinity, regulates pH, and is beneficial for suspension stability. The liquid filtration reducer is emulsified asphalt. The weighting material is high-density inert material barite BaSO4, which can significantly increase the density of the drilling fluid system. Core samples used for evaluating dynamic permeability recovery values: dense sandstone cores with artificial fractures. The experimental results are shown in Table 2 below.

[0052] As shown in Table 2, the oil-based drilling fluid with the reservoir protectant of this invention has a significantly improved ability to plug the core, a significantly reduced filtration loss during dynamic contamination, and a dynamic permeability recovery value that increased from 53.06% to 89.27% ​​and 90.93%, respectively. By degrading the nano-micro plugging agent, the density of the blockage layer formed by the solid phase of the drilling fluid in the pore channels can be broken down, reducing the flow resistance of oil and gas resources and achieving the purpose of reservoir protection.

[0053] Table 2 Evaluation of the protection effect of fractured core reservoirs

[0054]

[0055] (3) The reservoir protectant synthesized in Example 1 was used to prepare an oil-based drilling fluid. The effect of the prepared oil-based drilling fluid on the protection of shale oil core reservoirs was investigated. The experimental results are shown in Table 3.

[0056] Drilling fluid formulation: 1750mL white oil + 8% emulsifier + 2% organic clay + 4% filtration loss reducer + 750mL water (20% CaCl2 solution) + 2% CaO (50g) + 3% liquid filtration loss reducer (DR-NS) + 2% reservoir protectant for oil-based drilling fluid (Example 1), wherein the emulsifier is an oleic acid amide surfactant, the organic clay is quaternary ammonium salt modified bentonite, the filtration loss reducer is oxidized asphalt, and the liquid filtration loss reducer (DR-NS) is emulsified asphalt.

[0057] Table 3 Evaluation of Shale Oil Core Reservoir Protection Effect

[0058]

[0059] As shown in Table 3, the average permeability recovery value of shale oil cores is 90.97%, indicating that the reservoir protectant of the present invention can effectively protect shale oil reservoirs.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A reservoir protectant for oil-based drilling fluids, characterized in that, The reservoir protectant comprises, by weight, 100 parts solvent oil, 7-18 parts emulsifier, 20-50 parts surface-modified biodegradable nano-micro plugging agent, 6-17 parts surface-modified acid-soluble nano-inert particles, and 3-5 parts suspending and dispersing agent; The surface-modified biodegradable nano / micro plugging agent is prepared through the following process: 100 parts of biodegradable polyester and 2-8 parts of chain extender are added to the reaction vessel of a blending extruder and heated to 60-75°C. Nitrogen gas is introduced at 0.5 MPa-0.7 MPa. The reaction is carried out at 170-190°C. After the reaction is completed, the reaction vessel is pressurized and the reactants are extruded and granulated. After the granules are cooled and shaped, they are frozen to -10°C to -20°C and ground into nano-micron particles. The nano-micron particles are added to an aqueous solution of surfactant to modify the surface of the particles. Then, they are heated to 50°C-60°C and dried to obtain the surface-modified biodegradable nano-micron blocking agent. The acid-soluble nano-inert particles in the surface-modified acid-soluble nano-inert particles are selected from one or more combinations of nano-calcium carbonate, nano-manganese tetroxide, nano-chitosan and nano-cellulose; the acid-soluble nano-inert particles are surface-treated with a treatment agent to make them hydrophobic, and the treatment agent is sodium hexametaphosphate, sodium pyrophosphate, tartaric acid or sodium dodecylbenzenesulfonate. The suspending dispersant is N-hydroxy-N-sulfonic acid hydroxy-3-siloxane pyroline salt or N-dimethylaminopropyl-N-triethylsilylmethyl perfluoroalkyl sulfonamide.

2. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The solvent oil is selected from one or more of coconut oil, cottonseed oil, castor oil, rapeseed oil, and vegetable oil-modified biodiesel.

3. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The emulsifier is selected from one or more of alkylolamides, sorbitan fatty acid esters, and higher fatty acid calcium.

4. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The biodegradable polyester is selected from one or more of polylactic acid, polyhydroxy fatty acid ester, polypropylene carbonate, polypropylene glutarate, polybutylene succinate, polybutylene adipate, polybutylene adipate copolyester, polyester-polyhydroxy fatty acid ester, polydioxanone, and furanyl dicarboxylate polyester.

5. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The chain extender is selected from one or a combination of two or more alcohol chain extenders and amine chain extenders.

6. The reservoir protectant for oil-based drilling fluid according to claim 5, characterized in that, The alcohol chain extender is selected from one or more combinations of 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, diethylene glycol, triethylene glycol, neopentyl glycol, sorbitol, and diethylaminoethanol; the amine chain extender is selected from one or more combinations of 4,4'-methylenebis(2-chloroaniline) and liquid MOCA modified with formaldehyde, ethylenediamine, and N,N-dihydroxy(diisopropyl)aniline.

7. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The surfactant is 1,4-bis(trimethylammonium)-2-[tris(trimethylsiloxy)]-2-ene oxide.

8. The reservoir protectant for oil-based drilling fluid according to claim 1, characterized in that, The concentration of the surfactant aqueous solution is 0.5% to 1.5% by mass.

9. A method for preparing a reservoir protectant for oil-based drilling fluid according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: The emulsifier is added to the solvent oil, and then the surface-modified biodegradable nano-micro plugging agent, the surface-modified acid-soluble nano-inert particles, and the suspending dispersant are added in sequence. The mixture is then stirred and reacted to obtain the reservoir protectant.

10. An oil-based drilling fluid comprising the reservoir protectant according to any one of claims 1-8.

11. The oil-based drilling fluid according to claim 10, characterized in that, In the oil-based drilling fluid, the reservoir protectant has a volumetric mass fraction of 1.5% to 3.5% relative to the oil-based drilling fluid emulsion.

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