A colloidal emulsifier and its preparation method and application

Abstract

The present invention provides a colloidal emulsifier and a preparation method and application thereof. The colloidal emulsifier is prepared based on a reversible addition-fragmentation chain transfer (RAFT) polymerization method, wherein a hydrophilic compound, an initiator, and a small molecule chain transfer agent are reacted to obtain a hydrophilic intermediate; a hydrophobic compound is further added to the reaction system of the hydrophilic intermediate to obtain a multi-block amphiphilic macromolecular intermediate; a pH-responsive compound, an initiator, and a small molecule chain transfer agent are reacted to obtain a pH stimulus-responsive macromolecular intermediate with an active end; and finally, the multi-block amphiphilic macromolecular intermediate, the pH stimulus-responsive macromolecular intermediate, and polymethyl methacrylate (PMMA)-coated nanoparticles are reacted to obtain a colloidal emulsifier. The colloidal emulsifier of the present invention has both the advantages of a macromolecular emulsifier and the characteristics of a particle emulsifier, and has good emulsification stability and reversal stability. The self-reversing drilling fluid added with the colloidal emulsifier of the present invention has excellent comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluid, and in particular relates to a colloidal emulsifier and a preparation method and application thereof. Background Art

[0002] Conventional water-in-oil drilling fluids usually have high emulsification stability and strong oil wetting properties, which will produce strong oil wettability to cuttings, drill strings and formations in contact with continuous oil phases, avoiding a series of drilling problems caused by water-sensitive shale instability caused by the use of water-based drilling fluids. However, conventional oil-based drilling fluids will produce a series of subsequent problems, such as: changes in the wettability of formations and cuttings, difficulty in removing mud cakes, decreased cementing strength, emulsion clogging of formations, difficulty in handling oil-containing cuttings, and high handling costs. This has led to a contradiction between the drilling efficiency of oil-based drilling fluids and the production capacity of oil and gas wells and environmental protection, which not only hinders the promotion and application of oil-based drilling fluids, but also seriously affects the benefits of exploration and development of oil and gas resources. In the application cases reported abroad, the reversible emulsion drilling fluid system has insufficient temperature resistance and low density, and cannot meet the technical requirements of high-temperature and high-pressure deep well and ultra-deep well oil and gas drilling operations. Domestic reversible emulsion drilling fluids are still in their infancy, and there is a large gap with foreign research. The existing emulsifiers are short-chain emulsifiers with a temperature resistance of less than 150°C and low emulsification efficiency. They are prone to demulsification due to stimulus reversal, which restricts the development of the system. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a colloidal emulsifier and a preparation method and application thereof. The colloidal emulsifier is prepared based on the reversible addition-fragmentation chain transfer (RAFT) polymerization method. Specifically, the amphiphilic "macromolecule" and the pH-responsive "macromolecule" are designed to adjust their hydrophilic and lipophilic properties and responsive properties. The "macromolecule" and the nanoparticles are then cross-linked and polymerized through a cross-linking agent and a spacer monomer to form a core, and a colloidal emulsifier with a dense inner core is prepared by a one-pot method. The colloidal emulsifier is used in drilling fluids, and can improve the emulsification stability, filter cake removal and switchability of the drilling fluid phase in the range of 100 to 200°C. The technical solution of the present invention is:

[0004] In a first aspect, the present invention provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0005] Step 1, reacting a hydrophilic compound, an initiator, and a small molecule chain transfer agent in a solvent 1 to obtain a hydrophilic intermediate; continuing to add a hydrophobic compound to the reaction system of the hydrophilic intermediate to react, crystallizing after the reaction is completed, filtering, and drying to obtain a solid, which is a multi-block amphiphilic macromolecular intermediate;

[0006] Step 2, reacting a pH-responsive compound, an initiator, and a small molecule-+chain transfer agent in a second solvent, crystallizing after the reaction, filtering, and drying to obtain a solid, thereby obtaining a pH stimulus-responsive macromolecular intermediate having an active end;

[0007] Step 3, dissolving the multi-block amphiphilic macromolecular intermediate, pH stimulus responsive macromolecular intermediate, and polymethyl methacrylate (PMMA)-coated nanoparticles in solvent three, and then adding a crosslinker, a spacer monomer, and an initiator to react. After the reaction is completed, the solvent and unreacted monomers are removed to obtain a colloidal emulsifier.

[0008] Further, the control parameters of the two-step reaction in step 1 are: the system is oxygen-free, the reaction temperature is 40-100°C, the reaction time is 1-48h, the hydrophilic compound, the hydrophobic compound, the initiator, and the small molecule chain transfer agent are respectively fed in parts by weight: 1-100 parts, 1-100 parts, 0.001-10 parts, 0.001-10 parts, and the mass ratio of the hydrophobic compound to the hydrophilic compound is (1-20): (1-20). Preferably, the control parameters of the two-step reaction in step 1 are: the system is oxygen-free, the reaction temperature is 60-90°C, the reaction time is 12-24h, the hydrophilic compound, the hydrophobic compound, the initiator, and the small molecule chain transfer agent are respectively fed in parts by weight: 1-50 parts, 1-50 parts, 0.01-1 parts, 0.01-1 parts, and the mass ratio of the hydrophobic compound to the hydrophilic compound is (2-10): 1.

[0009] Furthermore, the control parameters of the reaction in step 2 are: the system is oxygen-free, the reaction temperature is 40-100° C., the reaction time is 1-48 hours, and the pH-responsive compound, initiator, and small molecule chain transfer agent are added in proportions by weight: 1-200 parts, 0.001-10 parts, and 0.001-10 parts, respectively.

[0010] Preferably, the control parameters of the reaction in step 2 are: the system is anaerobic, the reaction temperature is 60-90°C, the reaction time is 12-24h, and the pH-responsive compound, initiator, and small molecule chain transfer agent are added in proportions by weight: 1-100 parts, 0.01-1 parts, and 0.01-1 parts, respectively.

[0011] Furthermore, the control parameters of the reaction in step 3 are: reaction temperature 40-100° C., reaction time 1-48 h, and the components are proportioned by weight: 1-200 parts of multi-block amphiphilic macromolecular intermediate, 1-200 parts of pH stimulus responsive macromolecular intermediate, 0.001-20 parts of initiator, 1-100 parts of PMMA-coated nanoparticles, 1-500 parts of cross-linking agent, and 0-20 parts of spacer monomer.

[0012] Preferably, the control parameters of the reaction in step 3 are: the system is oxygen-free, the reaction temperature is 60-80°C, the reaction time is 1-12h, and the components are matched in parts by weight: 1-40 parts of multi-block amphiphilic macromolecular intermediates, 1-20 pH stimulus responsive macromolecules, 0.01-1 parts of initiators, 10-50 parts of PMMA-coated nanoparticles, 10-200 parts of cross-linking agents, and 0-10 parts of spacer monomers.

[0013] Furthermore, the hydrophilic compound is selected from one or more of the following groups: acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, maleic anhydride, dimethyldiallylammonium chloride, N'N-dimethylacrylamide.

[0014] Further, the initiator is selected from one of the following groups: S-2-cyano-2-propyl-S'-ethyl dithiocarbonate, 2,2'-azobisisobutylamidine dihydrochloride (V-50), azobisisobutyronitrile (AIBN), azobisisovaleronitrile, azobisisoheptanenitrile, azobiscyclohexylcarbonitrile.

[0015] Further, the small molecule chain transfer agent is selected from one of the following groups: benzyl trithiocarbonate propionic acid (BSPA), 3-benzylthiothiocarbonylthiopropionic acid, benzyl trithiocarbonate propionic acid, 4-cyano-4-[[(dodecylthio)thiomethyl]thio]pentanoic acid, S-(2-cyanoprop-2-yl)-S-dodecyl trithiocarbonate, dibenzyl trithiocarbonate, carbazole-9-dithiobenzyl ester, 2-(dodecyl trithiocarbonate)-2-methylpropionic acid (DMP), 2-[[(dodecylmercapto)thiomethyl]thio]-2-methylbenzoic acid methyl ester, 4-cyano-4-(phenylthiothiothio)pentanoic acid N-succinimidyl ester and derivatives of the foregoing compounds.

[0016] Furthermore, the solvent one, the solvent two, and the solvent three are respectively selected from one or a mixture of toluene, petroleum ether, tetrahydrofuran, ethanol, 1,4-dioxane, 1,4-dioxane, n-butyl ether, ethyl ether, toluene, petroleum ether, xylene, cyclohexane, acetone, butanone, ethyl acetate, butyl acetate, propyl acetate, cyclohexanone, and DMF.

[0017] Further, the hydrophobic compound is selected from one or more of the following groups: polyethylene glycol diacrylate, ethylene glycol dimethacrylate, hydroxyethyl acrylate, dodecyl methyl acrylate, ethylene glycol diacrylate, alkyl methacrylate, polyether methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isooctyl methacrylate, N-4-vinylphenyl-N,N-dimethylamine, styrene, divinylbenzene, 1-bromo-4-vinylbenzene, 1,4-di(4-isopropylphenyl)benzene, and 4-vinylbenzylpyrrolidine.

[0018] Further, the pH-responsive compound is selected from one of the following groups: acrylic acid, N-isopropylacrylamide, glutamic acid, L-histidine, aspartic acid, dimethylaminoethyl acrylate, carbamate, 1-(4-vinylbenzyl)-1H-imidazole, N-2-vinylbenzyl-N,N-dimethylamine, N-4-vinylphenyl-N,N-dimethylamine, vinylpyridine, 2-morpholinoethyl methacrylate, benzylsulfonamide, N-vinylcarbazole, and morpholinoethyl acrylate (MEMA).

[0019] Furthermore, in the PMMA-coated nanoparticles, the nanoparticles are one or more of nano-silicon dioxide, nano-aluminum oxide, nano-zinc oxide, and nano-ferroferric oxide.

[0020] Preferably, the preparation method of the PMMA-coated nanoparticles adopts a rotary spraying method.

[0021] Furthermore, the crosslinking agent is selected from one or more of 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate (HDDMA), N,N'-bisacrylcystamine (BAC), and divinylbenzene (DVB).

[0022] Furthermore, the spacer monomer is n-butyl acrylate or n-butyl methacrylate.

[0023] In a second aspect, the present invention provides a colloidal emulsifier obtained by the above-mentioned preparation method.

[0024] In a third aspect, the present invention provides a drilling fluid using the above-mentioned colloidal emulsifier.

[0025] Optionally, the drilling fluid is composed of the following parts by weight: oil phase one: 30-70 parts; water phase: 30-70 parts; colloidal emulsifier: 3-8 parts; auxiliary emulsifier: 0.5-4 parts; organic soil: 0.5-3 parts; filtration reducer: 2-6 parts; alkalinity regulator: 0.1-3 parts; wetting agent: 0.5-3 parts; shearing agent: 0.5-5 parts; weighting material: 0-800 parts; bound acid microcapsules or bound alkali microcapsules: 8-30 parts.

[0026] Optionally, the oil phase one is at least one of diesel, white oil, gas-to-liquid, aviation kerosene, and biodiesel.

[0027] Furthermore, the aqueous phase is a calcium chloride aqueous solution with a mass percentage concentration of 0% to 30%.

[0028] Furthermore, the auxiliary emulsifier is a mixture of one or more of SPAN series, Brij series, Tween series, AEO series, and OP series such as diethanolamine oleate sorbitan monopalmitate, diethanolamine coconut oil sorbitan monopalmitate, triethanolamine oleate sorbitan monopalmitate, and monoethanolamine oleate sorbitan monopalmitate.

[0029] Furthermore, the organic soil is a quaternary ammonium product of montmorillonite.

[0030] Furthermore, the fluid loss reducer is a mixture of one or more of sulfonated asphalt, modified sulfonated asphalt, oxidized asphalt, modified oxidized asphalt, humic acid amide, and oil-soluble polymer fluid loss reducer.

[0031] Furthermore, the alkalinity regulator is calcium oxide and / or magnesium oxide.

[0032] Furthermore, the wetting agent is lecithin, hexadecyltrimethylammonium bromide, imidazoline amphoteric surfactant, dodecylene glycol polyether, or a mixture of any one of them.

[0033] Furthermore, the shearing agent is one of myristic acid, aluminum isooctanoate, poly(adipic acid-hexamethylenediamine-high purity dimer acid) fatty acid polyamide, SRRH-O-HVis oil-based drilling fluid shearing agent (Shaanxi Senrui Petroleum Technology Development Co., Ltd.), HIRHEO oil-based shearing agent (Jingzhou Jiahua Technology Co., Ltd.), and poly(octadecyl methacrylate-styrene-triethyleneamine) ternary amide oil-soluble copolymer.

[0034] Furthermore, the weighting material is at least one of limestone, barite and hematite.

[0035] In a fourth aspect, the present invention provides a method for preparing a self-reversing drilling fluid, comprising the following steps:

[0036] Step 1, the composition is as follows according to weight: oil phase 1: 30-70 parts; water phase: 30-70 parts; colloidal emulsifier: 3-8 parts; auxiliary emulsifier: 0.5-4 parts; organic soil: 0.5-3 parts; fluid loss reducer: 2-6 parts; alkalinity regulator: 0.1-3 parts; wetting agent: 0.5-3 parts; shearing agent: 0.5-5 parts; weighting material: 0-800 parts; bound acid microcapsules or bound alkali microcapsules: 8-30 parts;

[0037] Step 2, adding the colloidal emulsifier into the oil phase 1 and stirring at a speed of 10000 rpm-12000 rpm for 10 to 30 minutes;

[0038] Step 3, at the same speed, continue to add the auxiliary emulsifier and stir for 10-30 minutes, add the organic soil and stir for 10-30 minutes, and then add the water phase and emulsify for 30-40 minutes;

[0039] Step 4, further adding a fluid loss reducer, an alkalinity regulator, a shearing agent, and a wetting agent in sequence, stirring for 10 to 20 minutes at the same speed after each treatment agent is added;

[0040] Step 5, further adding a weighting material and stirring for 10-30 minutes; then adding bound acid microcapsules or bound base microcapsules as required, stirring at 1000-3000 rpm for 10-30 minutes to obtain.

[0041] The adding of bound acid microcapsules or bound alkali microcapsules as required refers to adding them before the drilling fluid with the weighting material is aged, or adding them after the drilling fluid with the weighting material is aged.

[0042] Furthermore, the preparation method of the bound acid microcapsules or the bound base microcapsules comprises:

[0043] (1) Add 50 to 100 parts of capsule wall material to 100 to 300 parts of oil phase 2, heat and stir at 30° C. to 120° C. until the raw material is dissolved;

[0044] (2) weighing 10 to 50 parts of a solid acid or a solid base and adding it to the above-mentioned mixed solution to suspend the particles, and stirring at a speed of 200 rpm to 5000 rpm for 10 minutes to 6 hours to form a solid-in-oil (S / O) suspension liquid;

[0045] (3) further adding a non-solvent until the mixed solution condenses, and continuing to heat and stir at a constant temperature of 30° C. to 120° C. for 2 to 24 hours;

[0046] (4) Cool naturally to room temperature, let stand to separate the supernatant, repeatedly wash the precipitate with a non-solvent, and air-dry.

[0047] Furthermore, the capsule wall material is selected from one of ethyl cellulose (degree of substitution 2.4-3.0) and its derivatives, toluene, glucose, sucrose, gelatin, stearic acid, polyethylene, polystyrene, polyurethane, polyvinyl pyrrolidone, urea-formaldehyde resin, polyurethane, and polymethyl methacrylate.

[0048] Furthermore, the second oil phase is a mixture of one or more of paraffin, cyclohexane, toluene, benzene, cyclopentane and n-dodecane.

[0049] Furthermore, the solid acid is at least one of solid aminosulfonic acid, sulfonic acid, oxalic acid, tartaric acid, citric acid, trichloroacetic acid and solid hydrochloric acid.

[0050] Furthermore, the solid alkali is sodium hydroxide and / or potassium hydroxide.

[0051] Furthermore, the non-solvent is at least one of dichloromethane, chloroform and petroleum ether.

[0052] In a fifth aspect, the present invention provides a method for controlling the acid / alkali stimulation response of the self-reversing drilling fluid, which specifically comprises:

[0053] Method 1: When bound acid microcapsules are added to the drilling fluid, the drilling fluid is stirred at a speed of 1000-3000 pm for 10-45 hours to release the solid acid from the capsule wall, thereby adjusting the pH value of the drilling fluid to 1-6.5; the HLB value of the colloidal emulsifier is increased, and the emulsion is an oil-in-water drilling fluid;

[0054] Method 2: When bound alkali microcapsules are added to the drilling fluid, the drilling fluid is stirred at a speed of 1000-3000 pm for 10h-45h to release the solid alkali from the capsule wall, thereby adjusting the pH value of the drilling fluid to 7-12; the HLB value of the colloidal emulsifier is reduced, and the emulsion is an oil-in-water drilling fluid.

[0055] The high-temperature, high-density, self-reversing, reversible water-in-oil drilling fluid of the present invention has the following beneficial effects.

[0056] First, the colloidal emulsifier of the present invention has both the advantages of macromolecular emulsifiers and the characteristics of particle emulsifiers, and has good emulsification stability and reversal stability. When used alone, it can form an emulsion resistant to 180°C, and the continuous phase precipitation rate after aging at 180°C / 16h and standing for 3 days is less than 10%.

[0057] Second, the self-reversing drilling fluid with the colloidal emulsifier of the present invention has good rheology, low filtration loss, good suspension stability, no weighted material sedimentation and demulsification phenomenon in the range of 100°C to 200°C; and good stability, the demulsification voltage is greater than 400V; high temperature aging does not affect the smooth reversal of the emulsion and the stability of the emulsion; the drilling fluid before and after aging can be reversed into water-in-oil drilling fluid by acid / base response, the demulsification voltage is 0V to 20V, the performance of oil-in-water drilling fluid and water-in-oil drilling fluid is equivalent, and the high temperature and high pressure filtration loss is less than 10mL. The reversal time between oil-in-water drilling fluid and water-in-oil drilling fluid can be adjusted and is greater than 3 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is the infrared spectrum of the colloidal emulsifier in Example 1 of the present invention, wherein the upper line is the pH stimulus responsive macromolecule and the lower line is the colloidal emulsifier.

[0059] Figure 2 This is a particle size diagram of the colloidal emulsifier in Example 1 of the present invention.

[0060] Figure 3 This is an optical microscope image of the colloidal emulsifier in Example 1 of the present invention.

[0061] Figure 4 The graph is a graph of the oil phase separation rate of the colloidal emulsifier versus time in Example 1 of the present invention.

[0062] Figure 5 1 is a particle size distribution diagram of the drilling fluid in Example 11 of the present invention, wherein Figure (1) is a particle size distribution diagram of the water-in-oil drilling fluid; Figure (2) is a particle size distribution diagram of the oil-in-water drilling fluid.

[0063] Figure 6 These are experimental graphs of the filter cake removal rate of the drilling fluid of Example 11 of the present invention, wherein (a) is an experimental graph for the period of 0 to 9 hours, and (b) is an experimental graph for the period of more than 9 hours. DETAILED DESCRIPTION

[0064] In the description of the present invention, it should be noted that, if the specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0065] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0066] Example 1

[0067] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0068] ① Synthesis of active amphiphilic macromolecules: Add 10 parts of hydrophilic compound acrylic acid, 0.01 parts of initiator azobisisobutyronitrile AIBN, and 0.2 parts of small molecule chain transfer agent trithiocarbonate DMP into a 100 mL three-necked flask, dissolve in 100 parts of solvent 1,4-dioxane, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C and react for 12 hours to complete the polymerization of the hydrophilic block.

[0069] Continue to add 20 parts of hydrophobic compound styrene and a small amount of initiator AIBN 0.01 parts, heat to 70 ° C for reaction for 12 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with tetrahydrofuran, precipitate with petroleum ether, and filter, repeat purification 3 times, and vacuum dry to obtain a multi-block amphiphilic macromolecule with active ends.

[0070] ② Weigh 5 parts of dimethylaminoethyl acrylate, 0.01 parts of AIBN initiator, and 0.02 parts of trithiocarbonate DMP, a small molecule chain transfer agent, and dissolve them in 50 parts of 1,4-dioxane solvent. Deoxygenate with nitrogen for 30 minutes, and heat to 70°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 20 parts of ethyl acetate and precipitate with 100 parts of petroleum ether to precipitate the polymer. Repeat the purification three times and vacuum dry to obtain a pH stimulus-responsive macromolecule.

[0071] ③ Dissolve the active amphiphilic macromolecule (10 parts) and pH stimulus responsive macromolecule (5 parts) in 50 parts of ethanol, add 10 parts of PMMA pre-coated nano-silica, 150 parts of cross-linking agent divinylbenzene DVB and 1 part of spacer monomer n-butyl acrylate, add 0.2 parts of initiator AIBN, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C for several hours to react for 12 hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0072] The infrared spectrum of the colloidal emulsifier obtained in this example is as follows: Figure 1 As shown in the figure, the upper line is the pH stimulus responsive macromolecule and the lower line is the colloidal emulsifier. -1 Broad absorption peak, 1055cm, is the stretching vibration peak of hydroxyl group -1 C=S stretching vibration peak, 2930cm -1 and 2874cm -1 It is the position of the asymmetric stretching vibration peak of methylene. 1159.14cm -1 It is the stretching vibration peak of tertiary amine. When the macromolecule forms a core-crosslinked star polymer, 839.9 cm -1 The out-of-plane deformation vibration of para-substituted benzene and the -1 and 712cm-1 The peaks caused by the out-of-plane deformation vibration of meta-substituted benzene appeared in these two places, which shows that the molecular structure of the colloidal emulsifier meets the design requirements.

[0073] The particle size of the colloidal emulsifier obtained in this embodiment is as follows: Figure 2 As shown, the average particle size of the colloidal emulsifier is 298 nm and the particle size distribution is narrow.

[0074] The optical microscope image of the colloidal emulsifier obtained in this example is as follows: Figure 3 As shown, the particle size distribution of the colloidal emulsifier is uniform and less than 1 micron.

[0075] Add 2 or 4 parts of the colloidal emulsifier prepared in this example to 50 parts of diesel, add 50 parts of deionized water and stir at 10000 rpm for 30 minutes. Place in an aging oven and heat roll at 180°C / 16h, take out and let stand, and detect the ratio of the oil phase precipitation to the total volume, which is the precipitation rate. The comparative sample is to replace the colloidal emulsifier (4 parts) with lauroyl polyethylene polyamine emulsifier, and place in an aging oven and heat roll at 150°C / 16h. Figure 4 It can be seen that the stability of the colloidal emulsifier prepared by using only Example 1 is good, and the oil phase precipitation rate is prohibited to be less than 10% after aging at 180°C / 16h for 3 days. In the comparative example, the oil phase precipitation is higher than 40% after aging at 150°C / 16h, and the emulsion stability is poor, tending to demulsify.

[0076] Example 2

[0077] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0078] ① Add 10 parts of hydrophilic compound diallyldimethylammonium chloride, 0.01 parts of AIBN initiator, and 0.2 parts of small molecule chain transfer agent trithiocarbonate DMP into a three-necked flask, dissolve them in 100 parts of solvent DMF, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C and react for 6 hours to complete the polymerization of the hydrophilic block.

[0079] Continue to add 20 parts of hydrophobic compound hydroxyethyl methacrylate, add a small amount of initiator AIBN initiator 0.01 parts, heat to 70 ° C for 12 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with tetrahydrofuran, precipitate with petroleum ether, filter, and purify repeatedly for 3 times. After vacuum drying, a multi-block amphiphilic macromolecule with active ends is obtained.

[0080] ② Weigh 5 parts of N-isopropylacrylamide, 0.01 parts of AIBN initiator, and 0.02 parts of trithiocarbonate DMP, a small molecule chain transfer agent, and dissolve them in 40 parts of 1,4-dioxane solvent. Deoxygenate with nitrogen for 30 minutes, and heat to 70°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 20 parts of ethyl acetate and precipitate with 100 parts of petroleum ether to precipitate the polymer. Repeat the purification three times and vacuum dry to obtain a pH stimulus-responsive macromolecule.

[0081] ③ Dissolve the active amphiphilic macromolecule (20 parts) and pH stimulus responsive macromolecule (12 parts) in 100 parts of ethanol, add 30 parts of PMMA pre-coated nano-alumina, 15 parts of crosslinking agent 1,6-hexanediol diacrylate and 1 part of spacer monomer n-butyl acrylate, add 0.01 parts of 2,2'-azobisisobutylamidine dihydrochloride V-50 initiator, pass nitrogen and deoxygenate for 30 minutes, heat to 70°C for several hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0082] Example 3

[0083] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0084] ① Add 5 parts of hydrophilic compound acrylic acid AA, 4 parts of maleic anhydride, 0.05 parts of S-2-cyano-2-propyl S'-ethyl dithiocarbonate initiator, and 0.2 parts of small molecule chain transfer agent BSPA into a three-necked flask, dissolve them in 200 parts of solvent 1,4-dioxane, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C and react for 18 hours to complete the polymerization of the hydrophilic block.

[0085] Continue to add 40 parts of the hydrophobic compound hydroxyethyl acrylate and a small amount of initiator AIBN 0.05 parts, heat to 70 ° C for 18 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with toluene, precipitate with petroleum ether, and filter. Repeat purification for 3 times, and vacuum dry to obtain a multi-block amphiphilic macromolecule with active ends.

[0086] ② Weigh 5 parts of dimethylaminoethyl acrylate, 0.05 parts of S-2-cyano-2-propyl S'-ethyl dithiocarbonate initiator, and 0.2 parts of small molecule chain transfer agent benzyl trithiocarbonate propionic acid, dissolve in 40 parts of solvent 1,4-dioxane, pass nitrogen to deoxygenate for 30 minutes, and heat to 70°C for 18 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 40 parts of ethyl acetate and precipitate with 100 parts of petroleum ether to precipitate the polymer. Repeat the purification three times and vacuum dry to obtain a pH stimulus-responsive macromolecule.

[0087] ③ Dissolve 10 parts of active amphiphilic macromolecules and 5 parts of pH stimulus responsive macromolecules in 200 parts of ethanol, add 30 parts of PMMA pre-coated nano zinc oxide, 200 parts of crosslinking agent HDDMA and 5 parts of spacer monomer n-butyl methacrylate, add 0.2 parts of initiator S-2-cyano-2-propyl S'-ethyl dithiocarbonate, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C for several hours to react for 12 hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0088] Example 4

[0089] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0090] ① Add 8 parts of hydrophilic compound acrylamide AM, 5 parts of 2-acrylamide-2-methylpropanesulfonic acid, 0.05 parts of V-50 initiator, and 0.2 parts of small molecule chain transfer agent 4-cyano-4-[[(dodecylthio)thioketonemethyl]thio]pentanoic acid into a three-necked flask, dissolve in 100 parts of solvent tetrahydrofuran, pass nitrogen to deoxygenate for 30 minutes, heat to 60°C and react for 12 hours to complete the polymerization of the hydrophilic block.

[0091] Continue to add 10 parts of styrene hydrophobic compound, 20 parts of ethylene glycol dimethacrylate, add a small amount of initiator 2,2'-azobisisobutylamidine dihydrochloride V-50 initiator 0.05 parts, heat to 70 ° C for 12 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with tetrahydrofuran, precipitate with petroleum ether, filter, and purify repeatedly for 3 times. After vacuum drying, a multi-block amphiphilic macromolecule with active ends is obtained.

[0092] ② Weigh 5 parts of MEMA, 0.02 parts of V-50 initiator, and 0.02 parts of small molecule chain transfer agent 4-cyano-4-[[(dodecylthio)thiomethyl]thio]pentanoic acid, dissolve in 60 parts of tetrahydrofuran solvent, pass nitrogen to deoxygenate for 30 minutes, and heat to 60°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 60 parts of tetrahydrofuran, precipitate with 100 parts of petroleum ether, and precipitate the polymer. Repeat purification 3 times, vacuum dry, and obtain pH stimulus-responsive macromolecules.

[0093] ③ Dissolve 10 parts of active amphiphilic macromolecules and 5 parts of pH stimulus responsive macromolecules in 200 parts of ethanol, add 40 parts of PMMA pre-coated nano-silica, 50 parts of crosslinking agent HDDA and 5 parts of spacer monomer n-butyl acrylate, add 0.2 parts of 2,2'-azobisisobutylamidine dihydrochloride V-50 initiator, pass nitrogen and deoxygenate for 30 minutes, heat to 60°C for several hours to react for 12 hours, and stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0094] Example 5

[0095] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0096] ① Add 10 parts of hydrophilic compound acrylic acid AA, 8 parts of dimethyldiallylammonium chloride, 0.1 parts of azobisisovaleronitrile initiator, and 0.2 parts of small molecule chain transfer agent benzyl trithiocarbonate propionic acid into a three-necked flask, dissolve in 200 parts of solvent toluene, deoxygenate with nitrogen for 30 minutes, heat to 80°C and react for 12 hours to complete the polymerization of the hydrophilic block.

[0097] Continue to add 10 parts of hydrophobic compound methyl acrylate, 20 parts of polyethylene glycol diacrylate (molecular weight 5000), add a small amount of initiator azobisisovaleronitrile 0.1 parts, heat to 80 ° C for 6 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, dry, dissolve with tetrahydrofuran, precipitate with petroleum ether, filter, repeat purification twice, and vacuum dry to obtain a multi-block amphiphilic macromolecule with active ends.

[0098] ② Weigh 5 parts of aspartic acid, 0.1 parts of azobisisovaleronitrile initiator, and 0.2 parts of benzyl trithiocarbonate propionic acid, a small molecule chain transfer agent, and dissolve them in 50 parts of toluene solvent, deoxygenate with nitrogen for 30 minutes, and heat to 70°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 40 parts of toluene, precipitate with 100 parts of petroleum ether, and precipitate the polymer. Repeat the purification three times, vacuum dry, and obtain a pH stimulus-responsive macromolecule.

[0099] ③ Dissolve the active amphiphilic macromolecule (12 parts) and pH stimulus responsive macromolecule (4 parts) in 100 parts of ethanol, add 40 parts of PMMA pre-coated nano-silica, add 100 parts of crosslinking agent N,N'-bisacrylcystamine BAC and 8 parts of spacer monomer n-butyl acrylate BA, add 0.2 parts of initiator AIBN, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C for several hours to react for 12 hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0100] Example 6

[0101] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0102] ① Add 12 parts of hydrophilic compound acrylic acid AA, 4 parts of dimethyldiallylammonium chloride, 5 parts of 2-acrylamide-2-methylpropanesulfonic acid, 0.1 parts of azobiscyclohexylcarbonitrile initiator, and 0.2 parts of small molecule chain transfer agent 3-dodecylthiothiocarbonylthiopropionic acid into a three-necked flask, dissolve in 200 parts of solvent cyclohexane, deoxygenate with nitrogen for 30 minutes, heat to 70°C and react for 6 hours to complete the polymerization of the hydrophilic block.

[0103] Continue to add 10 parts of styrene hydrophobic compound, 30 parts of ethylene glycol dimethacrylate, add a small amount of initiator 0.1 parts of azobiscyclohexylcarbonitrile, heat to 70 ° C for 12 hours, precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with cyclohexane, precipitate with petroleum ether, filter, and purify repeatedly for 3 times. After vacuum drying, a multi-block amphiphilic macromolecule with active ends is obtained.

[0104] ② Weigh 5 parts of L-histidine, 0.01 parts of azobiscyclohexylcarbonitrile initiator, and 0.02 parts of small molecule chain transfer agent 3-benzylthiothiocarbonylthiopropionic acid, dissolve in 50 parts of solvent cyclohexane, pass nitrogen to deoxygenate for 30 minutes, and heat to 70°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 50 parts of cyclohexane, precipitate with 100 parts of petroleum ether, and precipitate the polymer. Repeat purification 3 times, vacuum dry, and obtain pH stimulus responsive macromolecules.

[0105] ③ Dissolve 20 parts of active amphiphilic macromolecules and 8 parts of pH stimulus responsive macromolecules in cyclohexane, add 50 parts of PMMA pre-coated nano-ferroferric oxide, 80 parts of crosslinking agent HDDA and 10 parts of spacer monomer n-butyl acrylate, add 0.2 parts of initiator azobisisobutyronitrile, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C for several hours to react for 24 hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0106] Example 7

[0107] This embodiment provides a method for preparing a colloidal emulsifier, comprising the following steps:

[0108] ① Add 5 parts of hydrophilic compound acrylic acid AA, 5 parts of N'N-dimethylacrylamide, 0.01 parts of azobisisoheptanenitrile initiator, and 1 part of small molecule chain transfer agent 3-benzylthiothiocarbonylthiopropionic acid into a flask, dissolve them in 50 parts of 1,4-dioxane, pass nitrogen to deoxygenate for 30 minutes, heat to 70℃ and react for 12 hours to complete the polymerization of the hydrophilic block.

[0109] Continue to add 20 parts of divinylbenzene, a hydrophobic compound, 13 parts of hydroxyethyl acrylate, 8 parts of dodecyl methyl acrylate, and a small amount of initiator 0.01 parts of azobisisoheptanenitrile, and heat to 70°C for 12 hours. Precipitate with petroleum ether, collect the precipitate by suction filtration, and dry. Dissolve with tetrahydrofuran, precipitate with petroleum ether, and filter. Repeat purification for 3 times, and vacuum dry to obtain a multi-block amphiphilic macromolecule with active ends.

[0110] ② Weigh 5 parts of N-4-vinylphenyl-N,N-dimethylamine, 0.1 parts of azobisisoheptanonitrile initiator, and 0.5 parts of small molecule chain transfer agent 3-benzylthiothiocarbonylthiopropionic acid, dissolve in 50 parts of solvent 1,4-dioxane, pass nitrogen to deoxygenate for 30 minutes, and heat to 70°C for 12 hours. Terminate the reaction in an ice bath. Dilute the reaction solution with 50 parts of 1,4-dioxane, precipitate with 100 parts of petroleum ether, and precipitate the polymer. Repeat purification 3 times, vacuum dry, and obtain pH stimulus-responsive macromolecules.

[0111] ③ Dissolve the active amphiphilic macromolecule (30 parts) and pH stimulus responsive macromolecule (12 parts) in 100 parts of ethanol, add 50 parts of PMMA pre-coated nano-silica, 100 parts of crosslinking agent HDDA and 120 parts of styrene DVB and 5 parts of spacer monomer n-butyl acrylate, add 0.2 parts of initiator AIBN, pass nitrogen to deoxygenate for 30 minutes, heat to 70°C for several hours to react for 12 hours, stir in an ice water bath until cooled. Remove the solvent and unreacted monomers, and freeze-dry to obtain a pH stimulus responsive hetero-arm core cross-linked colloidal emulsifier.

[0112] Table 1 GPC results of process products and colloidal emulsifiers

[0113]

[0114]

[0115] In Examples 1 to 7, regardless of whether it is a macromolecular or colloidal emulsifier, the PDI is less than 1.2. As the reaction proceeds, the molecular weight of the polymer increases, and the number of macromolecules is 10 to 20.

[0116] Example 8

[0117] This embodiment provides a method for preparing bound acid microcapsules or bound base microcapsules, comprising the following steps:

[0118] Dissolve 50 parts of ethyl cellulose and polystyrene in 100 parts of oil phase cyclohexane at 70°C and stir until the raw materials are dissolved. Add 30 parts of oxalic acid / potassium hydroxide (particle size 1μm to 200μm) to the above mixed solution and stir at 1000rpm for 1 hour to form a solid-in-oil (S / O) suspension. Slowly add non-solvent petroleum ether until the mixed solution condenses, continue stirring for 6 hours, heat to 70°C, and then cool naturally to room temperature. Pour out the supernatant, repeat washing and precipitation, and drying to obtain solid particles.

[0119] Example 9

[0120] This embodiment provides a method for preparing bound acid microcapsules or bound base microcapsules, comprising the following steps:

[0121] Dissolve 20 parts of polyvinyl pyrrolidone and 60 parts of ethyl cellulose in 200 parts of oil phase paraffin, and stir at 70°C until the raw materials are dissolved. Add 30 parts of solid hydrochloric acid / sodium hydroxide (particle size 1μm~200μm) to the above mixed solution, stir at 1000rpm for 2 hours to form an oil-in-solid phase (S / O) suspension. Slowly add non-solvent dichloromethane until the mixed solution condenses, continue stirring for 3 hours, heat to 38°C, then naturally cool to room temperature, pour out the supernatant, repeat washing and precipitation, and drying to obtain solid particles.

[0122] Example 10

[0123] This embodiment provides a method for preparing bound acid microcapsules or bound base microcapsules, comprising the following steps:

[0124] Dissolve 20 parts of polyurethane, 10 parts of gelatin, and 50 parts of ethyl cellulose in 200 parts of oil phase paraffin, and stir at 70°C until the raw materials are dissolved. Add 30 parts of citric acid / sodium hydroxide (particle size 1μm to 200μm) to the above mixed solution, stir at 2000rpm for 4 hours to form an oil-in-solid (S / O) suspension liquid. Slowly add non-solvent dichloromethane until the mixed solution condenses, continue stirring for 6 hours, heat to 38°C, then naturally cool to room temperature, pour out the supernatant, repeat washing and precipitation, and drying to obtain solid particles.

[0125] Embodiment 11

[0126] The present embodiment provides a method for preparing a self-reversing drilling fluid, comprising the following steps: adding 3 parts of the colloidal emulsifier prepared in Example 1 to 50 parts of 0# diesel, stirring at a speed of 10,000 rpm for 20 minutes, adding 1.5 parts of auxiliary emulsifier Span80, 1.5 parts of hexadecyltrimethylammonium bromide modified organic soil, and stirring at a speed of 10,000 rpm for 5 to 20 minutes. Add 50 parts of a 25% calcium chloride aqueous solution and emulsify at 10,000 rpm for 20 to 40 minutes. Add 3 parts of sulfonated asphalt modified by a fluid loss reducer, 2.5 parts of alkalinity regulator calcium oxide, 3 parts of shearing agent poly (octadecyl methacrylate-styrene-triethyleneamine) triamide oil-soluble copolymer (see patent 2022107587270), 3 parts of wetting agent lecithin, and stir for 10 to 20 minutes after each treatment agent is added. Finally, add a weighting agent (barite) to adjust the drilling fluid density to 2.2 g / cm 3 , and stir for 10-30 minutes.

[0127] Examples 12 to 18

[0128] Examples 12 to 18 were prepared by referring to the process of Example 11 and according to the materials in Table 2.

[0129] The preparation of the oil-soluble polymer fluid loss reducer used in the embodiment of the present invention refers to the following literature: Zhou Yan, Pu Xiaolin, Liu Lu, Wang Lei. Synthesis and performance evaluation of polymer fluid loss reducer for oil-based drilling fluid [J]. Fine Chemicals, 2019, 36(03): 520-526.

[0130] Table 2 Feeding conditions of Examples 12 to 18

[0131]

[0132]

[0133]

[0134] The testing standard for drilling fluid refers to "GB / T 16783.2-2012 Field Testing of Drilling Fluids in Petroleum and Natural Gas Industry Part 2: Oil-based Drilling Fluids".

[0135] Example 19

[0136] The density of Example 11 was 2.2 g / cm 3 (Add weighting material limestone or barite to adjust to this density, the same as in the following examples) The reversible drilling fluid is aged at 200°C / 16h. 15 parts of bound acid microcapsules (Example 9) or 15 parts of bound alkali microcapsules (Example 9) are added, and the measured properties are shown in Table 3.

[0137] Table 3 Performance of reversible drilling fluid in Example 11

[0138] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 513 123.5 98 25.5 6 / 7.5 3.8 7.5 — O / W 10 126 99 27 6.5 / 7.5 4.2 6.2 8.2 W / O 509 121.5 97 24.5 5 / 6.5 4.2 7.2 9.1

[0139] Density: 2.2g / cm 3 After the reversible emulsified drilling fluid was aged at 200℃ / 16h, the bound acid capsules were added for 8.2 hours to release the acid, the emulsifier molecules became more hydrophilic, and the fluid was reversed to oil-in-water drilling fluid. The bound alkali capsules were added for 9.1 hours to release the alkali, the emulsifier molecules became more lipophilic, and the fluid was reversed to water-in-oil drilling fluid.

[0140] Figure 5 The particle size distribution diagrams of water-in-oil drilling fluid and oil-in-water drilling fluid are given. No matter it is water-in-oil drilling fluid or oil-in-water drilling fluid, the particle size distribution of the emulsion is less than 1μm, and the particle size distribution of the emulsion is uniform.

[0141] Example 20

[0142] The density of Example 12 was 2.0 g / cm 3 The reversible drilling fluid was aged at 200°C / 16h. 20 parts of bound acid microcapsules (Example 8) or 20 parts of bound base microcapsules (Example 8) were added, and the measured properties were shown in Table 4.

[0143] Table 4 Performance of reversible drilling fluid in Example 12

[0144] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 497 116.5 90 26.5 5 / 6 3.6 7 — O / W 8 115.5 92 23.5 5 / 6.5 3.8 6.0 12 hours W / O 491 117 93 24 4.0 / 5.5 4.2 7.2 11.2 hours

[0145] Density: 2.0g / cm 3 After the reversible emulsified drilling fluid was aged at 200℃ / 16h, the bound acid capsules were added for 12 hours to release the acid, the hydrophilicity of the emulsifier molecules increased, and the fluid was reversed to water-in-oil drilling fluid. The bound alkali capsules were added for 11.2 hours to release the alkali, the lipophilicity of the emulsifier molecules increased, and the fluid was reversed to oil-in-water drilling fluid.

[0146] Example 21

[0147] The density of Example 13 was 1.8 g / cm 3 The reversible drilling fluid was aged at 180°C / 16h. 25 parts of bound acid microcapsules (Example 9) or 25 parts of bound base microcapsules (Example 9) were added, and the measured properties were shown in Table 5.

[0148] Table 5 Performance of reversible drilling fluid in Example 13

[0149] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 488 91.5 72 19.5 4 / 5.5 3.8 7.5 — O / W 8 90.5 70 20.5 4 / 5 4.2 6 13.5 W / O 479 92.5 73 19.5 4.5 / 6.5 4.4 7.5 14.5

[0150] Density: 1.8 g / cm 3After the reversible emulsified drilling fluid was aged at 180℃ / 16h, the bound acid capsules were added for 13.5 hours to release the acid, the hydrophilicity of the emulsifier molecules was enhanced, and the fluid was reversed to water-in-oil drilling fluid. The bound alkali capsules were added for 14.5 hours to release the alkali, the lipophilicity of the emulsifier molecules was enhanced, and the fluid was reversed to oil-in-water drilling fluid.

[0151] Example 22

[0152] The density of Example 14 was 1.6 g / cm 3 The reversible drilling fluid was aged at 150°C / 16h. 10 parts of bound acid microcapsules (Example 10) or 10 parts of bound base microcapsules (Example 10) were added, and the measured properties were shown in Table 6.

[0153] Table 6 Performance of reversible drilling fluid in Example 14

[0154] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 473 87.5 70 17.5 4.5 / 5.5 3.6 7 — O / W 10 89 71 18 4 / 5.5 3.8 5 6 W / O 477 88.5 72 16.5 4.5 / 6.5 4.0 7 6.3

[0155] Density: 1.6 g / cm 3 After the reversible emulsified drilling fluid was aged at 150℃ / 16h, the bound acid capsules were added for 6 hours to release the acid, the hydrophilicity of the emulsifier molecules increased, and the fluid was reversed to water-in-oil drilling fluid. The bound alkali capsules were added for 6.3 hours to release the alkali, the lipophilicity of the emulsifier molecules increased, and the fluid was reversed to oil-in-water drilling fluid.

[0156] Example 23

[0157] The density of Example 15 was 1.4 g / cm 3 The reversible drilling fluid was aged at 120°C / 16h. 15 parts of bound acid microcapsules (Example 8) or 15 parts of bound base microcapsules (Example 8) were added, and the measured properties were shown in Table 7.

[0158] Table 7 Performance of reversible drilling fluid in Example 15

[0159] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 463 72.5 58 14.5 3 / 4.5 3.4 7.2 — O / W 10 72 57 15 3 / 4.5 3.8 5.5 7.1 W / O 469 71.5 57 14.5 3 / 4.5 4.2 7.2 7.8

[0160] Density: 1.4g / cm 3 After the reversible emulsified drilling fluid was aged at 120℃ / 16h, the bound acid capsules were added for 7.1 hours to release the acid, the emulsifier molecules became more hydrophilic, and the fluid was reversed to oil-in-water drilling fluid. The bound alkali capsules were added for 7.8 hours to release the alkali, the emulsifier molecules became more lipophilic, and the fluid was reversed to water-in-oil drilling fluid.

[0161] Example 24

[0162] The density of Example 16 was 1.0 g / cm 3 The reversible drilling fluid was aged at 100°C / 16h. 8 parts of bound acid microcapsules (Example 8) or 8 parts of bound base microcapsules (Example 8) were added, and the measured properties were shown in Table 8.

[0163] Table 8 Performance of reversible drilling fluid in Example 16

[0164] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 435 49 38 11 2 / 2.5 2.2 7 — O / W 8 50.5 39 11.5 2 / 3 2.6 5 3.2 W / O 427 51.5 40 11.5 2.5 / 3.5 2.4 7 3.8

[0165] Density: 1.0g / cm 3 After the reversible emulsified drilling fluid was aged at 100℃ / 16h, the bound acid capsules were added for 3.2 hours to release the acid, the emulsifier molecules became more hydrophilic, and the fluid was reversed to oil-in-water drilling fluid. The bound alkali capsules were added for 3.8 hours to release the alkali, the emulsifier molecules became more lipophilic, and the fluid was reversed to water-in-oil drilling fluid.

[0166] Example 25

[0167] The density of Example 17 was 1.2 g / cm 3 The reversible drilling fluid was aged at 120°C / 16h. 15 parts of bound acid microcapsules (Example 9) or 15 parts of bound base microcapsules (Example 9) were added, and the measured properties were shown in Table 9.

[0168] Table 9 Performance of reversible drilling fluid in Example 17

[0169] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 401 53.5 43 10.5 3.0 / 4.0 3.6 7 — O / W 9 49 38 11 3.0 / 3.5 3.8 5.8 5.3 W / O 409 51.5 41 10.5 3.5 / 4.0 3.8 7.2 5.8

[0170] Density: 1.2g / cm 3 After the reversible emulsified drilling fluid was aged at 120℃ / 16h, the bound acid capsules were added for 5.3 hours to release the acid, the hydrophilicity of the emulsifier molecules increased, and the fluid was reversed to oil-in-water drilling fluid. The bound alkali capsules were added for 5.8 hours to release the alkali, the lipophilicity of the emulsifier molecules increased, and the fluid was reversed to water-in-oil drilling fluid.

[0171] Example 26

[0172] The density of Example 18 was 2.2 g / cm 3 Reversible drilling fluid aging 150℃ / 16h. Add 30 parts of bound acid microcapsules (Example 10) or 30 parts of bound alkali microcapsules (Example 10), and the measured properties are shown in Table 10

[0173] Table 10 Performance of reversible drilling fluid in Example 18

[0174] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / h W / O 468 108.5 88 20.5 4 / 5.5 3.8 8 — O / W 8 112.5 90 22.5 4 / 5 3.2 6.5 13.5 W / O 471 109 88 21 4.5 / 5.5 3.4 8 14.6

[0175] Density: 2.2g / cm 3 After the reversible emulsified drilling fluid was aged at 150℃ / 16h, the bound acid capsules were added for 13.5 hours to release the acid, the hydrophilicity of the emulsifier molecules increased, and the fluid was reversed to oil-in-water drilling fluid. The bound alkali capsules were added for 14.6 hours to release the alkali, the lipophilicity of the emulsifier molecules increased, and the fluid was reversed to water-in-oil drilling fluid.

[0176] Comparative Example 1

[0177] The drilling fluid prepared according to Example 17 was poured into a high temperature aging tank and aged at 120°C for 16 hours. 15% hydrochloric acid and 15% sodium hydroxide alkali solution (same as Comparative Examples 3 to 5) were used to stimulate reversal, and the properties were measured and shown in Table 11.

[0178] Table 11 Performance of reversible drilling fluid of comparative example 1

[0179] type ES AV PV PY <![CDATA[G 10s / G 10min ]]> <![CDATA[FL HTHP / mL]]> Filtrate pH Reversal time / min W / O 387 50.5 40 10.5 2.5 / 3.0 4.8 7 — O / W 10 47 37 10 2.0 / 3.0 5.8 5.2 10min W / O 373 48.5 38 10.5 2.0 / 3.5 5.4 6.8 15min

[0180] The data in Table 11 show that using only colloidal emulsifier can form a reversible drilling fluid, which can be reversed after adding acid and alkali solutions. The time required for reversal is short (10 to 15 minutes), but delayed reversal cannot be achieved. Therefore, the addition of bound acid / alkali capsules can enhance the performance of colloidal emulsifiers.

[0181] Comparative Example 2

[0182] The drilling fluid prepared according to Example 17 was poured into a high temperature aging tank, wherein the colloidal emulsifier was replaced with a conventional tall oil emulsifier, and aged at 120°C for 16 hours. 15 parts of bound acid microcapsules (Example 9) or 15 parts of bound alkali microcapsules (Example 9) were added, and the properties were measured and shown in Table 12.

[0183] Table 12 Performance of reversible drilling fluid of comparative example 1

[0184]

[0185] The data in Table 12 show that the use of conventional emulsifiers, even with bound acid microcapsules and bound base microcapsules, cannot achieve reversal.

[0186] Example 27

[0187] In addition, the present invention further investigates the filter cake removal rate experiment to prove that the colloidal emulsifier of the present invention will not have adverse effects on the filter cake removal of the drilling fluid.

[0188] The filter cakes obtained from the drilling fluids of Examples 11 to 18 and Comparative Examples 1 to 2 in a high temperature and high pressure filter loss meter were placed in 15% acid solution, and the filter cake removal rate was calculated by measuring the mass difference of the filter cake on the filter paper before and after immersion. The results are shown in Table 13.

[0189] Table 13 Filter cake removal efficiency of reversible drilling fluid

[0190]

[0191]

[0192] In Examples 11 to 18, the delayed removal time of the filter cake is long, the time required for complete reversal is less than 1 hour, and the complete removal efficiency of the filter cake is higher than 96%. In Comparative Example 1, the time for the filter cake to start dissolving is short, mainly starting from the surface of the filter cake, and then entering the filter cake dissolving skeleton, the complete removal of the filter cake takes a long time, and the complete dissolution efficiency of the filter cake is lower than 91%. The conventional drilling fluid filter cake removal efficiency is poor, and the filter cake dissolution time is long.

[0193] Figure 6 The experimental graphs of the filter cake soaking of the drilling fluid of Example 11 for 0 to 9 hours are given. (a) is the experimental graph for 0 to 9 hours, and (b) is the experimental graph for more than 9 hours. Within 0 to 9 hours, the filter cake remains intact. After more than 9 hours, the filter cake is completely dissolved, and the filter cake is delayed and removed with high removal efficiency. It can be seen that the addition of the colloidal emulsifier, combined with the action of bound acid microcapsules or bound base microcapsules, has a good effect on the filter cake removal performance of the drilling fluid.

[0194] Comparative Examples 3 to 5

[0195] Comparative Examples 3 to 5 investigate the related properties of conventional drilling fluids after adding the colloidal emulsifier of the present invention.

[0196] Comparative Example 3: Zhou Yan, Pu Xiaolin, Liu Lu, Wang Lei. Synthesis and performance evaluation of polymer fluid loss reducer for oil-based drilling fluid[J]. Fine Chemicals, 2019, 36(03): 520-526+533.

[0197] Referring to the formula and treatment agent in the above literature, the oil-water ratio is adjusted to 60:40, which is Comparative Example 3. Comparative Example 3 adds 30 parts of bound acid microcapsules (Example 10) or 30 parts of bound alkali microcapsules (Example 10) (Comparative Example 3-1). The main emulsion of Comparative Example 3 is replaced with the colloidal emulsifier of Example 1 (Comparative Example 3-2), and the aging temperature is 160°C / 16h.

[0198] Comparative Example 4: Ma Fengjie, Pu Xiaolin, Wang Bo, Yu Yuelin, Zhang Ping. Research and development of fluid loss reducer for oil-in-water drilling fluid[J]. Applied Chemical Industry, 2016, 45(10): 1820-1823.

[0199] Referring to the formula and treatment agent in the above literature, the oil-water ratio is adjusted to 50:50, which is Comparative Example 4; 15% hydrochloric acid is added to Comparative Example 4 (Comparative Example 4-1). The main emulsion of Comparative Example 4 is replaced with the colloidal emulsifier of Example 2 (Comparative Example 4-2), and the aging temperature is 180°C / 16h. 15% hydrochloric acid is added to Comparative Example 4-2 (Comparative Example 4-3). 15% alkali solution is added to Comparative Example 4-2 (Comparative Example 4-4).

[0200] Comparative Example 5: Study on high temperature resistant water-in-oil emulsion drilling fluid [D]. Gao Shengnan. Southwest Petroleum University. 2018.

[0201] Referring to the formula and treatment agent in the above literature, the oil-water ratio was adjusted to 65:35 and the density was 1.6g / cm 3 , which is Comparative Example 5. Comparative Example 5 adds 15 parts of bound acid microcapsules (Example 8) or 15 parts of bound alkali microcapsules (Example 8) (Comparative Example 5-1), and the aging temperature is 160°C / 16h. The main emulsion of Comparative Example 5 is replaced with the colloidal emulsifier of Example 3 (Comparative Example 5-2), and the aging temperature is 180°C / 16h.

[0202] The results are shown in Table 14.

[0203] Table 14 shows the drilling fluid related properties of Examples 3 to 5.

[0204]

[0205]

[0206]

[0207] Comparative Example 3 can withstand high temperatures of 150°C, but cannot be reversed by adding bound acid / base microcapsules. When the colloidal emulsifier is used instead, the system can not only be reversed, but the emulsification stability can also be improved. Comparative Example 4 cannot withstand high temperatures of 180°C, and the system demulsification voltage is lower than 400V, and cannot be reversed. A large amount of oil phase precipitates, and the rheological properties of the system deteriorate. After using the colloidal emulsifier of Example 2, the system has good emulsification stability and moderate rheology, and can also be reversed. According to the literature, Comparative Example 5 can only withstand 160°C. Above this temperature, the system performance decreases, and adding bound acid / base microcapsules cannot be reversed. When the colloidal emulsifier of Example 3 is used, the system temperature resistance is 180°C, and it can be reversed with a delayed reaction.

[0208] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a colloidal emulsifier, characterized in that: The following steps are involved: Step 1, reacting a hydrophilic compound, an initiator, and a small molecule chain transfer agent in a solvent 1 to obtain a hydrophilic intermediate; continuing to add a hydrophobic compound to the reaction system of the hydrophilic intermediate to react, crystallizing after the reaction is completed, filtering, and drying to obtain a solid, which is a multi-block amphiphilic macromolecular intermediate; Step 2, reacting a pH-responsive compound, an initiator, and a small molecule chain transfer agent in a second solvent, crystallizing after the reaction, filtering, and drying to obtain a solid, thereby obtaining a pH stimulus-responsive macromolecular intermediate having an active end; Step 3, dissolving the multi-block amphiphilic macromolecular intermediate, the pH stimulus responsive macromolecular intermediate, and the polymethyl methacrylate-capped nanoparticles in solvent 3, and then adding a crosslinking agent, a spacer monomer, and an initiator to react, and removing the solvent and unreacted monomers after the reaction to obtain a colloidal emulsifier; The hydrophilic compound is selected from one or more of the following groups: acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, maleic anhydride, dimethyldiallylammonium chloride, N'N dimethylacrylamide; The hydrophobic compound is selected from one or more of the following groups: polyethylene glycol diacrylate, ethylene glycol dimethacrylate, hydroxyethyl acrylate, dodecyl methyl acrylate, ethylene glycol diacrylate, polyether methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isooctyl methacrylate, N-4-vinylphenyl-N,N-dimethylamine, styrene, divinylbenzene, 1-bromo-4-vinylbenzene, 1,4-di(4-isopropylstyryl)benzene, 4-vinylbenzylpyrrolidine; The pH-responsive compound is selected from one of the following groups: N-isopropylacrylamide, glutamic acid, L-histidine, aspartic acid, dimethylaminoethyl acrylate, 1-(4-vinylbenzyl)-1H-imidazole, N-2-vinylbenzyl-N,N-dimethylamine, N-4-vinylbenzyl-N,N-dimethylamine, vinylpyridine, 2-morpholinylethyl methacrylate, benzylsulfonamide, N-vinylcarbazole, morpholinylethyl acrylate; In the polymethyl methacrylate coated nanoparticles, the nanoparticles are one or more of nano silicon dioxide, nano aluminum oxide, nano zinc oxide, and nano ferroferric oxide; The spacer monomer is n-butyl acrylate or n-butyl methacrylate.

2. A colloidal emulsifier, characterized in that: The method is used to prepare the product according to claim 1.

3. A drilling fluid, characterized in that: The colloidal emulsifier according to claim 2 is used.

4. A method for preparing a self-reversing drilling fluid, characterized in that: The following steps are involved: Step 1, the composition is as follows in parts by weight: oil phase 1: 30-70 parts; water phase: 30-70 parts; colloidal emulsifier as claimed in claim 2: 3-8 parts; auxiliary emulsifier: 0.5-4 parts; organic soil: 0.5-3 parts; fluid loss reducer: 2-6 parts; alkalinity regulator: 0.1-3 parts; Wetting agent: 0.5-3 parts; Shearing agent: 0.5-5 parts; Weighting material: 0-800 parts; Bound acid microcapsules or bound alkali microcapsules: 8-30 parts; Step 2, adding the colloidal emulsifier into the oil phase 1 and stirring at a speed of 10000 rpm-12000 rpm for 10-30 minutes; Step 3, at the same speed, continue to add the auxiliary emulsifier and stir for 10-30 minutes, add the organic soil and stir for 10-30 minutes, and then add the water phase and emulsify for 30-40 minutes; Step 4, further add a fluid loss reducer, an alkalinity regulator, a shearing agent, and a wetting agent in sequence, and stir at the same speed for 10 to 20 minutes after each treatment agent is added; Step 5, further adding a weighting material and stirring for 10-30 minutes; then adding bound acid microcapsules or bound base microcapsules as required, stirring at 1000-3000 rpm for 10-30 minutes to obtain.

5. The method for controlling the acid / alkali stimulus response of the self-reversing drilling fluid according to claim 4, characterized in that: Specifically include: Method 1: When bound acid microcapsules are added to the drilling fluid, the drilling fluid is stirred at a speed of 1000-3000 pm for 10-45 hours to release the solid acid from the capsule wall, thereby adjusting the pH value of the drilling fluid to 1-6.5; the HLB value of the colloidal emulsifier increases, and the emulsion is an oil-in-water drilling fluid; Method 2: When bound alkali microcapsules are added to the drilling fluid, the drilling fluid is stirred at a speed of 1000-3000 pm for 10-45 hours to release the solid alkali from the capsule wall, thereby adjusting the pH value of the drilling fluid to 7-12; the HLB value of the colloidal emulsifier is reduced, and the emulsion is an oil-in-water drilling fluid.

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