A surface modifier for drilling fluid, its preparation method, and its application.

Abstract

This invention provides a surface modifier for drilling fluids, its preparation method, and its application. The drilling fluid surface modifier of this invention comprises, by weight parts: 100-130 parts of a polyether-chain siloxane polymer; 60-80 parts of a block fluoroethylene copolymer; 60-70 parts of a higher acrylate polymer; 1-5 parts of a thiol; 5-10 parts of nanoparticles; 10-15 parts of polyethylene glycol; 7-9 parts of trimethylammonium chloride; 10-25 parts of dimethylammonium chloride; and 400-500 parts of deionized water. This drilling fluid surface modifier can alleviate liquid phase trapping damage in tight / shale reservoirs; it can also alleviate oil film damage and emulsification damage that may be caused by oil-based drilling fluids and subsequent water-based working fluids, thereby improving test yields.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, and in particular to a surface modification for drilling fluids, its preparation method, and its application. Background Technology

[0002] With the continuous increase in global energy consumption, the development of unconventional oil and gas resources has received widespread attention. Tight oil and gas and shale oil and gas are important components of unconventional oil and gas resources; therefore, the efficient development of unconventional oil and gas and shale oil and gas is of great significance to the development of unconventional oil and gas resources. Compared with conventional oil and gas reservoirs, tight oil and gas reservoirs and shale oil and gas reservoirs have extremely special geological conditions (high temperature, high pressure, high stress, and well-developed natural fractures), with more engineering operations, complex procedures, and greater safety risks. They are also more susceptible to severe reservoir damage during well construction and development and production stages.

[0003] Damage types in tight oil and gas reservoirs and shale oil and gas reservoirs mainly include solid phase blockage, fluid-sensitive damage, and liquid phase trapping damage. Oil-based drilling fluids have insufficient compatibility with subsequent water-based working fluids, the unblocking rate of solid phase plugging layers in acid solutions is less than 20%, and the unblocking capacity for liquid phase damage is poor. Among these, liquid phase trapping damage has an extremely serious impact on the reservoir. Therefore, it is necessary to develop a drilling fluid surface modifier that can alleviate oil film damage and emulsification damage that may be caused by the interaction between oil-based drilling fluids and subsequent water-based working fluids. Summary of the Invention

[0004] This invention provides a surface modifier for drilling fluids that can eliminate liquid phase trapping damage in tight / shale reservoirs; eliminate oil film damage and emulsification damage that may be caused by oil-based drilling fluids and subsequent water-based working fluids; and improve test yield.

[0005] This invention provides a method for preparing a surface modifier for drilling fluids. This method is simple and easy to operate.

[0006] The present invention provides a drilling fluid comprising the aforementioned surface modifier for drilling fluids, thereby reducing liquid phase trapping damage in oil and gas reservoirs.

[0007] This invention provides a surface modifier for drilling fluids, comprising, by weight parts:

[0008]

[0009] The surface modifier for drilling fluids as described above, wherein the polyether segment siloxane polymer comprises hydrophobic and hydrophilic groups;

[0010] The hydrophobic group is selected from polysiloxane segments and / or block fluoropolysiloxane segments;

[0011] The hydrophilic group is selected from ether groups and / or hydroxyl groups.

[0012] The drilling fluid surface modifier described above, wherein the polyether segment siloxane polymer is selected from at least one of polyether-modified polydimethylsiloxane, polyether-modified siloxane ester, branched polyether-modified polysiloxane, hydroxyl-terminated polyether-modified polydimethylsiloxane, polyether-modified siloxane phosphate, and ethoxylated polyether-modified trisiloxane.

[0013] The drilling fluid surface modifier described above, wherein the block fluoroethylene copolymer is selected from at least one of ethylene-tetrafluoroethylene copolymer, ethylene-trifluorochloroethylene copolymer, vinylidene-hexafluoroisobutylene copolymer, fluorinated ethylene propylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer; and / or,

[0014] The thiol is selected from at least one of 3-(1',3'-oxothiapentane)-2-butyritin, 2-methyl-1-butyritin, propyne-tetraethylene glycol-thiol, 1,3-propanedithiol, 1,6-hexanedithio, 1-p-menen-8-thiol, 2-methyl-1-butyritin, 2-methyl-3-furanthiol, n-dodecylthiol, 3-methyl-2-butyritin, 4-4-thiodiphenylthiol, n-dodecylthiol, 3,6-dioxo-1,8-octanedithiol, 3(dimethylamino)-1-propanethiol, and dodecyl tertiary thiol; and / or,

[0015] The nanoparticles are selected from at least one of hydrophobic nano-silica, nano-polysilicon, nano-graphite particles, and nano-titanium oxide; and / or,

[0016] The average particle size of the nanoparticles is 50-100 nm.

[0017] The drilling fluid surface modifier described above, wherein the number-average molecular weight of the polyethylene glycol is 500-6000; and / or,

[0018] The kinematic viscosity of the polyethylene glycol is 2.5-25 mm. 2 / s.

[0019] The drilling fluid surface modifier described above, wherein the higher acrylate polymer is obtained by copolymerization of higher acrylate monomers, acrylic monomers and ethylene monomers.

[0020] The drilling fluid surface modifier described above, wherein the trimethylammonium chloride is selected from at least one of dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, (3-carboxypropyl)trimethylammonium chloride, hexadecyltrimethylammonium chloride, benzyltrimethylammonium chloride, stearyltrimethylammonium chloride, hydroxypropyltrimethylammonium chloride, phenyltrimethylammonium chloride, and 3-chloro-2-hydroxypropyltrimethylammonium chloride; and / or,

[0021] The dimethylammonium chloride is selected from at least one of dimethyldiallylammonium chloride, dodecyl dimethyl benzylammonium chloride, (dimethylaminomethylene)dimethylammonium chloride, lauryl dimethylammonium chloride, (chloromethylene)dimethylammonium chloride, dioctadecyl dimethylammonium chloride, dioctyl dimethylammonium chloride, didecyl dimethylammonium chloride, polydiallyl dimethylammonium chloride, and propylene dioctadecyl dimethylammonium chloride.

[0022] The present invention provides a method for preparing the surface modifier for drilling fluid as described above, wherein the surface modifier is obtained by homogenizing and emulsifying the raw material system.

[0023] The raw material system comprises, by mass parts:

[0024]

[0025] The present invention provides a drilling fluid, wherein the drilling fluid surface modifier described above is included.

[0026] The drilling fluid as described above, wherein the surface modifier content of the drilling fluid is 0.2-1% by mass, based on the total mass of the drilling fluid.

[0027] This invention provides a surface modifier for drilling fluids. When used in drilling fluids, this surface modifier can effectively reduce the surface free energy and surface hydrophilicity of reservoir rocks, thereby helping to reduce liquid phase trapping damage in oil and gas reservoirs, especially in tight oil and gas reservoirs and shale oil and gas reservoirs.

[0028] The method for preparing the drilling fluid surface modifier of the present invention can prepare the above-mentioned drilling fluid surface modifier, and the preparation method is simple and easy to operate.

[0029] The drilling fluid of the present invention includes the above-mentioned surface modifier for drilling fluid. The drilling fluid can effectively reduce the surface free energy of reservoir rocks and reduce the surface hydrophilicity of reservoir rocks, thereby helping to reduce liquid phase trapping damage in oil and gas reservoirs, especially reducing liquid phase trapping damage in tight oil and gas reservoirs and shale oil and gas reservoirs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The surface water contact angle of limestone treated with drilling fluid prepared using the drilling fluid surface modifier in Example 2;

[0032] Figure 2 The ethylene glycol contact angle of the limestone surface after drilling fluid treatment, prepared with the drilling fluid surface modifier in Example 2;

[0033] Figure 3 The surface water contact angle of sandstone treated with drilling fluid prepared using the drilling fluid surface modifier in Example 2;

[0034] Figure 4 The ethylene glycol contact angle of the sandstone surface treated with drilling fluid prepared using the drilling fluid surface modifier in Example 2;

[0035] Figure 5 The surface water contact angle of Jimsar shale oil shale after drilling fluid treatment, prepared with the drilling fluid surface modifier in Example 2;

[0036] Figure 6 The surface glycol contact angle of Jimsar shale oil shale after drilling fluid treatment with the drilling fluid surface modifier prepared in Example 2;

[0037] Figure 7 The surface water contact angle of the Longmaxi Formation shale in Sichuan and Chongqing after treatment with drilling fluid prepared with the drilling fluid surface modifier in Example 2;

[0038] Figure 8 The surface ethylene glycol contact angle of the Sichuan-Chongqing Longmaxi Formation shale after treatment with drilling fluid prepared with the drilling fluid surface modifier in Example 2;

[0039] Figure 9 The surface water contact angle of limestone treated with drilling fluid prepared using the drilling fluid surface modifier in Example 3;

[0040] Figure 10 The ethylene glycol contact angle of the limestone surface treated with drilling fluid prepared with the drilling fluid surface modifier in Example 3;

[0041] Figure 11 The surface water contact angle of sandstone treated with drilling fluid prepared using the drilling fluid surface modifier in Example 3;

[0042] Figure 12 The ethylene glycol contact angle of the sandstone surface treated with drilling fluid prepared using the drilling fluid surface modifier in Example 3;

[0043] Figure 13 The surface water contact angle of Jimsar shale oil shale after drilling fluid treatment, prepared with the drilling fluid surface modifier in Example 3;

[0044] Figure 14 The surface glycol contact angle of Jimsar shale oil shale after drilling fluid treatment with the drilling fluid surface modifier prepared in Example 3;

[0045] Figure 15 The surface water contact angle of the Longmaxi Formation shale in Sichuan and Chongqing after treatment with drilling fluid prepared with the drilling fluid surface modifier in Example 3;

[0046] Figure 16 The ethylene glycol contact angle of the surface of the Longmaxi Formation shale in Sichuan and Chongqing after treatment with the drilling fluid prepared with the drilling fluid surface modifier in Example 3. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] A first aspect of the present invention provides a surface modifier for drilling fluids, wherein, by weight parts, it comprises:

[0049]

[0050] In this invention, the critical surface tension and critical micelle mass concentration of drilling fluid can be determined using the ring method. The critical surface tension of the drilling fluid is 17-21 mN / m, the critical micelle mass concentration is 0.04%-0.15%, and the HLB value is 5-10. The drilling fluid surface modifier of this invention includes a specific amount of a specific compound. When used in drilling fluid, this surface modifier readily and strongly adsorbs on the rock surface, reducing the surface energy of the reservoir rock and causing the surface of the reservoir rock to change from water wetting to intermediate wetting or oil wetting. This reduces the capillary pressure of the drilling fluid on the reservoir rock, promotes liquid phase backflow of the drilling fluid, and thus effectively reduces liquid phase trapping damage during the drilling process.

[0051] In this invention, further selection can be made of polyether segment siloxane polymers, block fluoroethylene copolymers, higher acrylate polymers, thiols, nanoparticles, polyethylene glycol, trimethylammonium chloride, and dimethylammonium chloride, in order to further improve the compatibility of each raw material and further reduce liquid phase trapping damage during the drilling process.

[0052] In some embodiments of the present invention, the polyether segment siloxane polymer comprises hydrophobic groups and hydrophilic groups;

[0053] The hydrophobic group is selected from polysiloxane segments and / or block fluoropolysiloxane segments;

[0054] The hydrophilic group is selected from ether and / or hydroxyl groups.

[0055] In some embodiments of the present invention, the polyether segment siloxane polymer is selected from at least one of polyether-modified polydimethylsiloxane, polyether-modified siloxane ester, branched polyether-modified polysiloxane, hydroxyl-terminated polyether-modified polydimethylsiloxane, polyether-modified siloxane phosphate, and ethoxylated polyether-modified trisiloxane.

[0056] In some embodiments of the present invention, the block fluoroethylene copolymer is selected from at least one of ethylene-tetrafluoroethylene copolymer, ethylene-trifluorochloroethylene copolymer, vinylidene-hexafluoroisobutylene copolymer, fluorinated ethylene propylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer. The present invention does not impose particular limitations on the degree of polymerization or molecular weight of the above polymers.

[0057] In some embodiments of the present invention, the thiol is selected from at least one of 3-(1',3'-oxothiapentane)-2-butyrithiol, 2-methyl-1-butyrithiol, propyne-tetraethylene glycol-thiol, 1,3-propanedithiol, 1,6-hexanedisulfide, 1-p-menen-8-thiol, 2-methyl-1-butyrithiol, 2-methyl-3-furanthiol, n-dodecylthiol, 3-methyl-2-butyrithiol, 4-4-thiodiphenylthiol, n-dodecylthiol, 3,6-dioxo-1,8-octanedithiol, 3(dimethylamino)-1-propanethiol, and dodecyl tertiary thiol; and / or,

[0058] The nanoparticles are selected from at least one of hydrophobic nano-silica, nano-polysilicon, nano-graphite particles, and nano-titanium oxide; and / or,

[0059] The average particle size of the nanoparticles is 50-100 nm.

[0060] In this invention, hydrophobic nano-silica refers to nano-silica with a contact angle greater than 90° for a 10μL water droplet.

[0061] In some embodiments of the present invention, the number average molecular weight of polyethylene glycol is 500-6000; and / or,

[0062] The kinematic viscosity of polyethylene glycol is 2.5-25 mm. 2 / s.

[0063] In some embodiments of the present invention, the higher acrylate polymer is obtained by copolymerization of higher acrylate monomers, acrylic monomers and ethylene monomers.

[0064] In a specific embodiment, the higher acrylate polymer can be obtained by a method including the following steps:

[0065] Add organic solvent and higher acrylate monomers to the reaction vessel, stir and heat to 50-60℃, add acrylic monomers, and continue to heat to 65-75℃;

[0066] An initiator and ethylene monomer are added to a reaction vessel to carry out a copolymerization reaction. After reacting for 1 to 2 hours, the solution is cooled, filtered or centrifuged to obtain a light blue transparent solution. The solution is then neutralized with alkali to a pH of 6-7 to obtain a high acrylate polymer.

[0067] In the above preparation process, the structural formula of the higher acrylate monomer can be CH3(CH2). m-1 OOCCH=CH2, where m is an even number from 3 to 18; the organic solvent can be at least one of n-hexane, ethylene glycol ether, styrene, ethylene ethyl ester, tetrahydrofuran, dimethylacetamide, and methyl ethyl ketone; the acrylic monomer can be at least one of lauryl acrylate, hydroxyethyl methacrylate, hydroxypropylene methacrylate, methyl acrylate, methyl methacrylate, isobornyl acrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, epoxy acrylate, 1,6-hexanediol diacrylate, and diethylene glycol diacrylate; the ethylene monomer can be at least one of styrene, vinyl acetate, tert-butyl vinyl ether, cyclohexyl vinyl ether, dodecyl vinyl ether, 1,4-butanediol divinyl ether, 1,4-butanediol monovinyl ether, and vinyl benzoate ether; the initiator can be at least one of boron trifluoride ethyl ether, dicumyl peroxide, benzoyl peroxide, and hydroxydicumyl peroxide; the alkaline solution can be an aqueous solution of sodium hydroxide and / or a potassium hydroxide solution.

[0068] Furthermore, the mass ratio of the higher acrylate monomer, organic solvent, ethylene monomer, acrylic monomer, and initiator is 100:(15-35):(3.5-4.5):(5.5-10.5):(15-35);

[0069] Ethylene monomers can be prepared into ethanol solutions with a mass fraction of 0.15%-0.25%; initiators can be prepared into aqueous solutions with a mass fraction of 0.1%-0.15%; acrylic monomers can be prepared into ethanol solutions with a mass fraction of 12%-18%.

[0070] The mass percentage of sodium hydroxide and / or potassium hydroxide in the alkaline solution is 10-20%.

[0071] In some embodiments of the present invention, trimethylammonium chloride is selected from at least one of dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, (3-carboxypropyl)trimethylammonium chloride, hexadecyltrimethylammonium chloride, benzyltrimethylammonium chloride, stearyltrimethylammonium chloride, hydroxypropyltrimethylammonium chloride, phenyltrimethylammonium chloride, and 3-chloro-2-hydroxypropyltrimethylammonium chloride; and / or,

[0072] Dimethylammonium chloride is selected from at least one of dimethyldiallylammonium chloride, dodecyl dimethyl benzylammonium chloride, (dimethylaminomethylene)dimethylammonium chloride, lauryl dimethylammonium chloride, (chloromethylene)dimethylammonium chloride, dioctadecyl dimethylammonium chloride, dioctyl dimethylammonium chloride, didecyl dimethylammonium chloride, polydiallyl dimethylammonium chloride, and propylene dioctadecyl dimethylammonium chloride.

[0073] A second aspect of the present invention provides a method for preparing a surface modifier for drilling fluid, wherein the modifier is obtained by homogenizing and emulsifying a raw material system.

[0074] The raw material system includes, by mass parts:

[0075]

[0076]

[0077] It is understood that the surface modifier for drilling fluid of the present invention can be obtained by homogenizing and emulsifying the raw material system composed above.

[0078] In some embodiments, the above-described raw material system can be placed in a high-pressure homogenizer filled with nitrogen and heated to 40°C under a pressure of 40-65 MPa for homogenization and emulsification treatment 5-10 times to obtain the surface modifier for drilling fluid of the present invention.

[0079] The method for preparing surface modifiers for drilling fluids of the present invention can produce surface modifiers for drilling fluids that can reduce the damage of liquid phase trapping in oil and gas reservoirs. The preparation method is simple to operate, has low production cost, and is suitable for widespread application and promotion.

[0080] A third aspect of the present invention provides a drilling fluid comprising the aforementioned surface modifier for drilling fluids.

[0081] It is understood that by matching the surface modifier of the drilling fluid of the present invention with other drilling fluid additives, a drilling fluid can be obtained. When this drilling fluid is used in oil and gas development, it can effectively reduce the surface free energy of reservoir rocks and reduce the surface hydrophilicity of reservoir rocks, thereby helping to reduce liquid phase trapping damage in oil and gas reservoirs, especially in tight oil and gas reservoirs and shale oil and gas reservoirs.

[0082] In some embodiments of the present invention, when the mass percentage of the surface modifier for the drilling fluid is 0.2-1% based on the total mass of the drilling fluid, the drilling fluid used in oil and gas development not only has low cost but also better reduces liquid phase trapping damage in oil and gas reservoirs. Further, the mass percentage of the surface modifier for the drilling fluid is 0.3-0.5% based on the total mass of the drilling fluid.

[0083] In some embodiments, treating the reservoir rock with a drilling fluid containing 0.3-0.5% by mass of a surface modifier can make the reservoir rock surface more oleophobic and hydrophobic. For example, it can make the ethylene glycol contact angle of the reservoir rock surface greater than 90° and the water contact angle of the reservoir rock surface greater than 110°. The reservoir rock can be selected from limestone, sandstone, shale, or tight shale.

[0084] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0085] Example 1

[0086] The drilling fluid surface modifier of this embodiment is prepared by a method including the following steps:

[0087] 1) Preparation of higher acrylate polymers:

[0088] Add 20 parts by mass of ethylene glycol ether and 100 parts by mass of higher acrylate monomer (m=12) to a reaction vessel, stir and heat to 55°C, add 6 parts by mass of isobornyl methacrylate, and continue heating to 75°C; add 15 parts by mass of dicumyl peroxide and 4 parts by mass of vinyl acetate to the reaction vessel for copolymerization reaction, and after reacting for 2 hours, cool the solution, filter or centrifuge to obtain a light blue transparent solution, neutralize with alkali solution to pH 7, and obtain the higher acrylate polymer;

[0089] The alkaline solution is a 15% sodium hydroxide aqueous solution by mass.

[0090] 2) Preparation of surface modifiers for drilling fluids

[0091] The autoclave was heated to 40°C and purged with nitrogen for 1 hour. Then, 100 parts by weight of branched polyether modified polysiloxane, 70 parts by weight of ethylene-chlorotrifluoroethylene copolymer, 65 parts by weight of high acrylate polymer, 2 parts by weight of 3-methyl-2-butanethiol, 7 parts by weight of nano-graphite particles, 12 parts by weight of polyethylene glycol, 8 parts by weight of hexadecyltrimethylammonium chloride, 15 parts by weight of dioctadecyldimethylammonium chloride, and 500 parts by weight of deionized water were added. The mixture was emulsified 10 times at 55 MPa to obtain a surface modifier for drilling fluid.

[0092] Among them, the branched polyether-modified polysiloxane has a number average molecular weight of 3500; the ethylene-chlorotrifluoroethylene copolymer has a number average molecular weight of 30000; and the average particle size D of the nano-graphite particles is... 50 The wavelength is 55 nm, the number average molecular weight of polyethylene glycol is 5000, and the kinematic viscosity is 23 mm. 2 / s.

[0093] Example 2

[0094] The drilling fluid surface modifier of this embodiment is prepared by a method including the following steps:

[0095] 1) Preparation of higher acrylate polymers:

[0096] Add 25 parts by mass of tetrahydrofuran and 100 parts by mass of higher acrylate monomers (m=14) to a reactor, stir and heat to 60°C, add 6.5 parts by mass of trimethylolpropane triacrylate, and continue heating to 75°C; add 18 parts by mass of boron trifluoride ether and 4.5 parts by mass of tert-butyl vinyl ether to the reactor for copolymerization reaction, and after reacting for 1.5 hours, cool the solution, filter or centrifuge to obtain a light blue transparent solution, neutralize with alkali solution to pH 6.5, and obtain the higher acrylate polymer;

[0097] The alkaline solution is an aqueous solution of sodium hydroxide with a mass percentage of 18%.

[0098] 2) Preparation of surface modifiers for drilling fluids

[0099] The autoclave was heated to 40°C and purged with nitrogen for 1 hour. Then, 100 parts by weight of polyether-modified siloxane phosphate, 65 parts by weight of vinylidene fluoride-chlorotrifluoroethylene copolymer, 62 parts by weight of high-grade acrylate polymer, 3 parts by weight of n-dodecyl mercaptan, 7 parts by weight of nano-titanium oxide, 12 parts by weight of polyethylene glycol, 8 parts by weight of hydroxypropyltrimethylammonium chloride, 15 parts by weight of (dimethylaminomethylene)dimethylammonium chloride, and 500 parts by weight of deionized water were added. The mixture was emulsified 10 times at 55 MPa to obtain a surface modifier for drilling fluid.

[0100] Among them, the number average molecular weight of polyether-modified siloxane phosphate is 1500; the number average molecular weight of vinylidene fluoride-chlorotrifluoroethylene copolymer is 500; the average particle size D50 of nano-titanium oxide is 70nm; the number average molecular weight of polyethylene glycol is 4000; and the kinematic viscosity is 20mm. 2 / s.

[0101] Example 3

[0102] The drilling fluid surface modifier of this embodiment is prepared by a method including the following steps:

[0103] 1) Preparation of higher acrylate polymers:

[0104] Add 20 parts by mass of methyl ethyl ketone and 100 parts by mass of higher acrylate monomers (m=10) to a reaction vessel, stir and heat to 55°C, add 6.5 parts by mass of trimethylolpropane trimethacrylate, and continue heating to 75°C; add 16 parts by mass of benzoyl peroxide and 4.5 parts by mass of 1,4-butanediol monovinyl ether to the reaction vessel for copolymerization reaction, and after reacting for 2 hours, cool the solution, filter or centrifuge to obtain a light blue transparent solution, neutralize with alkali solution to pH 7, and obtain the higher acrylate polymer;

[0105] The alkaline solution is an aqueous solution of potassium hydroxide with a mass percentage of 18%.

[0106] 2) Preparation of surface modifiers for drilling fluids

[0107] The autoclave was heated to 40°C and purged with nitrogen for 1 hour. Then, 110 parts by weight of hydroxyl-terminated polyether modified polydimethylsiloxane, 65 parts by weight of fluorinated ethylene propylene copolymer, 68 parts by weight of advanced acrylate polymer, 4 parts by weight of 1-p-menthen-8-thiol, 8 parts by weight of hydrophobic nano silica, 12 parts by weight of polyethylene glycol, 9 parts by weight of (3-carboxypropyl)trimethylammonium chloride, 18 parts by weight of (dimethylaminomethylene)dimethylammonium chloride, and 500 parts by weight of deionized water were added. The mixture was emulsified 10 times at 55 MPa to obtain a surface modifier for drilling fluid.

[0108] Among them, the number average molecular weight of hydroxyl polyether modified polydimethylsiloxane is 850; the number average molecular weight of fluorinated ethylene propylene copolymer is 5100; the average particle size D50 of hydrophobic nano-silica is 75nm; the number average molecular weight of polyethylene glycol is 3500; and the kinematic viscosity is 16mm. 2 / s.

[0109] Test case

[0110] The drilling fluid surface modifiers used in the examples and comparative examples were formulated into drilling fluids. The drilling fluids comprised 2% test soil and 0.5% drilling fluid surface modifier. The 2% test soil refers to 2g of test soil added to 100ml of distilled water, and the 0.5% drilling fluid surface modifier refers to 0.5g of drilling fluid surface modifier added to 100ml of distilled water. The test soil met the requirements of SY / T 5490 for drilling fluid test soil.

[0111] Different reservoir rocks were soaked in the above-mentioned drilling fluid to obtain test samples; the soaking time was 8 hours, the temperature was 100 degrees Celsius, the volume of the drilling fluid was 350 mL, the reservoir rock was a cylinder with a cross-section of a circle with a diameter of 5 cm and a height of 5 cm.

[0112] The surface contact angles of the samples were measured using a contact angle tester. The test results are shown in Table 1 and... Figure 1-16 The surface energy of the samples was tested using a contact angle meter, and the test results are shown in Table 1.

[0113] Table 1

[0114]

[0115] From Table 1 and Figure 1-16 It can be seen that when the surface modifier for drilling fluid prepared in the embodiments of the present invention is used in drilling fluid, it can improve the surface hydrophobicity and oleophobicity of reservoir rocks and reduce the surface free energy of reservoir rocks, which helps to reduce the liquid phase trapping damage of reservoir rocks.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface modifier for drilling fluids, characterized in that, According to the number of parts by weight: 100-130 parts of polyether segment siloxane polymer; 60-80 parts of block fluoroethylene copolymers; 60-70 parts of high-grade acrylic ester polymer; Thiols 1-5 parts; 5-10 parts of nanoparticles; 10-15 parts polyethylene glycol; 7-9 parts of trimethylammonium chloride; 10-25 parts of dimethylammonium chloride; 400-500 parts deionized water; The polyether segment siloxane polymer comprises hydrophobic and hydrophilic groups; the hydrophobic groups are selected from polysiloxane segments and / or block fluoropolysiloxane segments; the hydrophilic groups are selected from ether groups and / or hydroxyl groups. The polyether segment siloxane polymer is selected from at least one of polyether modified polydimethylsiloxane, polyether modified siloxane ester, branched polyether modified polysiloxane, hydroxyl-terminated polyether modified polydimethylsiloxane, polyether modified siloxane phosphate, and ethoxy polyether modified trisiloxane. The block fluoroethylene copolymer is selected from at least one of ethylene-tetrafluoroethylene copolymer, ethylene-trifluorochloroethylene copolymer, fluorinated ethylene propylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer.

2. The surface modifier for drilling fluid according to claim 1, characterized in that, The thiol is selected from at least one of 3-(1',3'-oxothiapentane)-2-butyritin, 2-methyl-1-butyritin, propyne-tetraethylene glycol-thiol, 1,3-propanedithiol, 1-p-menen-8-thiol, 2-methyl-1-butyritin, 2-methyl-3-furanthiol, n-dodecylthiol, 3-methyl-2-butyritin, 4-4-thiodiphenylthiol, n-dodecylthiol, 3,6-dioxo-1,8-octanedithiol, 3-(dimethylamino)-1-propanethiol, and dodecyl tertiary thiol; and / or, The nanoparticles are selected from at least one of hydrophobic nano-silica, nano-polysilicon, nano-graphite particles, and nano-titanium oxide; and / or, The average particle size of the nanoparticles is 50-100 nm.

3. The surface modifier for drilling fluid according to claim 1 or 2, characterized in that, The number-average molecular weight of the polyethylene glycol is 500-6000; and / or, The kinematic viscosity of the polyethylene glycol is 2.5-25 mm. 2 / s.

4. The surface modifier for drilling fluid according to claim 3, characterized in that, The higher acrylate polymer is obtained by copolymerization of higher acrylate monomers, acrylic monomers, and ethylene monomers; the structural formula of the higher acrylate monomers is CH3(CH2). m-1 OOCCH=CH2, where m is an even number from 3 to 18; the acrylic monomer is at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, methyl acrylate, methyl methacrylate, isobornyl acrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, epoxy acrylate, 1,6-hexanediol diacrylate, and diethylene glycol diacrylate; the ethylene monomer is at least one of styrene, vinyl acetate, tert-butyl vinyl ether, cyclohexyl vinyl ether, dodecyl vinyl ether, 1,4-butanediol divinyl ether, 1,4-butanediol monovinyl ether, and vinyl benzoate ether.

5. The surface modifier for drilling fluid according to claim 4, characterized in that, The trimethylammonium chloride is selected from at least one of dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, (3-carboxypropyl)trimethylammonium chloride, hexadecyltrimethylammonium chloride, benzyltrimethylammonium chloride, stearyltrimethylammonium chloride, hydroxypropyltrimethylammonium chloride, phenyltrimethylammonium chloride, and 3-chloro-2-hydroxypropyltrimethylammonium chloride; and / or, The dimethylammonium chloride is selected from at least one of dimethyldiallylammonium chloride, dodecyl dimethyl benzylammonium chloride, (dimethylaminomethylene) dimethylammonium chloride, lauryl dimethylammonium chloride, (chloromethylene) dimethylammonium chloride, dioctadecyl dimethylammonium chloride, dioctyl dimethylammonium chloride, didecyl dimethylammonium chloride, polydiallyl dimethylammonium chloride, and propylene dioctadecyl dimethylammonium chloride.

6. A method for preparing a surface modifier for drilling fluid according to any one of claims 1-5, characterized in that, It is obtained by homogenizing and emulsifying the raw material system; The raw material system comprises, by mass parts: 100-130 parts of polyether segment siloxane polymer; 60-80 parts of block fluoroethylene copolymers; 60-70 parts of high-grade acrylic ester polymer; Thiols 1-5 parts; 5-10 parts of nanoparticles; 10-15 parts polyethylene glycol; 7-9 parts of trimethylammonium chloride; 10-25 parts of dimethylammonium chloride; 400-500 parts of deionized water.

7. A drilling fluid, characterized in that, Includes the surface modifier for drilling fluids as described in any one of claims 1-5.

8. The drilling fluid according to claim 7, characterized in that, Based on the total mass of the drilling fluid, the surface modifier used in the drilling fluid has a mass percentage content of 0.2-1%.

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