Viscose latex emulsion added to drilling fluid for enhancing coal rock strength and method for preparing same

Abstract

The application belongs to the technical field of coal rock drilling, and relates to a viscous glue emulsion added in drilling fluid for enhancing the strength of coal rock and a preparation method thereof. The emulsion is prepared through emulsion polymerization, and the preparation raw materials thereof include an oil phase, an aqueous phase and a surfactant. The oil phase comprises a main monomer, a functional monomer, a crosslinking monomer, a first initiator and a solvent. The emulsion prepared by the application can block coal rock pores to prevent the invasion of drilling fluid, and can enhance the compressive strength of coal rock through the bonding effect. Meanwhile, the emulsion can reduce the risk of sticking due to the difference in affinity between coal and metal. Mixing the prepared emulsion with drilling fluid and soaking coal rock can basically maintain the original strength of the coal rock, and solve the problems of well wall instability and blockage of drilling in the process of coal rock gas drilling.

Description

Technical Field

[0001] This application belongs to the field of coal and rock drilling technology, and relates to a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, and its preparation method. Background Technology

[0002] In coal and rock gas drilling, the intrusion of drilling fluid into the coal and rock is a key issue leading to wellbore instability. Coal and rock are inherently porous and weakly cemented, allowing water and ions in the drilling fluid to easily penetrate the coal and rock through these pores. This damages the original structure of the coal and rock, significantly reducing its compressive strength and potentially causing drilling accidents such as coal and rock spalling and stuck drill bits, severely impacting drilling efficiency and safety.

[0003] Currently, existing technical solutions to this problem mainly fall into three categories: First, microsphere emulsion plugging technology based on polystyrene, which reduces drilling fluid intrusion by sealing coal and rock pores with microspheres. However, due to insufficient affinity between microspheres and coal and rock, its actual effect on maintaining coal and rock strength is limited. 1-2 Second, drilling fluid formulation improvement technology, by adding thickeners to inhibit coal and rock powdering, cannot solve the core problem of reduced coal and rock compressive strength, and the risk of rock fragmentation remains high. 3 Third, surface modification technology utilizes positively charged adhesives and surfactants to alter the hydrophilicity of coal and rock to reduce intrusion; however, its effectiveness is limited and its ability to protect the strength of coal and rock is insufficient. 4 .

[0004] The aforementioned technologies all suffer from drawbacks such as insufficient affinity for coal and rock and poor strength maintenance, making them unsuitable for drilling in complex coal and rock formations. Therefore, developing a drilling fluid additive that can efficiently seal coal and rock pores, enhance coal and rock strength, and possess excellent affinity is crucial for solving the wellbore instability problem in coal gas drilling.

[0005] References: 1.Wang L, Meng S, Chen W,et al.Development of and Study on an Anti-sloughing Plugging Agent Used in Drilling Fluids to Strengthen Coal Beds[J].Drilling Fluid and Completion Fluid, 2018, 35(5):46-49. DOI:10.3969 / j.issn.1001-5620.2018.05.009. 2. Wang Jianlong. Research on the instability mechanism of coal seam wellbore and drilling fluid technology in Yanchang Gas Field [D]. Southwest Petroleum University, 2019. 3. Geng Xueli, Su Yanhui, Zheng Xiaobin, et al. Research and application of drilling fluid for coal seams without solids protection [J]. Petroleum Drilling and Production Technology, 2017, 39(4):5. DOI:10.13639 / j.odpt.2017.04.011. 4. Song Jiwei. Experimental study on wellbore stabilization drilling fluid for co-production of "three gases" in coal-bearing strata in Southwest China [D]. China University of Geosciences, 2018. Summary of the Invention

[0006] One of the objectives of this application is to provide a viscose emulsion for use in drilling fluids to enhance the strength of coal and rock, and a method for preparing the same. The water-in-oil viscose emulsion is prepared by emulsion polymerization, which not only prevents drilling fluid from intruding and affecting the mechanical properties of coal and rock, but also enhances the compressive strength of coal and rock.

[0007] This application provides a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock, the raw materials for which include an oil phase, an aqueous phase and a surfactant.

[0008] In some embodiments of this application, the oil phase, by weight, comprises 3-6 parts of a main monomer, 0-3 parts of a functional monomer, 0-0.2 parts of a crosslinking monomer, a first initiator, and a solvent; in the oil phase, the total mass of the main monomer, functional monomer, crosslinking monomer, and first initiator accounts for 35%-100% of the total mass of the oil phase raw materials, and the solvent accounts for 65%~0%; the surfactant includes a main surfactant and a co-surfactant.

[0009] In some embodiments of this application, controlling the proportions of the three monomers in the oil phase can improve the mechanical properties of coal and rock. This is likely because an appropriate total amount of monomers results in moderate adhesive properties of the viscose particles formed by monomer polymerization, while excessive solvents dilute the functional groups in the monomers, weakening the synergistic effect of adhesion and sealing.

[0010] In some embodiments of this application, the host monomer includes, but is not limited to, one or more of acrylates, methacrylates, and vinyl carboxylate.

[0011] In some embodiments of this application, the acrylate includes, but is not limited to, one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate, isoamyl acrylate, octyl acrylate, isooctyl acrylate, and dodecyl acrylate.

[0012] In some embodiments of this application, the methacrylate includes, but is not limited to, one or more of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and isooctyl methacrylate.

[0013] In some embodiments of this application, the vinyl carboxylate includes, but is not limited to, one or more of vinyl acetate, vinyl propionate, and vinyl butyrate.

[0014] In some embodiments of this application, when a main monomer is selected, the main monomer is any one of ethyl acrylate, isooctyl methacrylate, and dodecyl acrylate.

[0015] In some embodiments of this application, when two or more main monomers are selected, the main monomers include dodecyl acrylate and methyl methacrylate in a mass ratio of (2-5):1.

[0016] In some embodiments of this application, when two or more main monomers are selected, the main monomers include ethyl acrylate and methyl methacrylate in a mass ratio of (1.5-4):1.

[0017] In some embodiments of this application, when two or more main monomers are selected, the main monomers include vinyl acetate and ethyl acrylate in a mass ratio of (2-3):1.

[0018] In some embodiments of this application, the use of short / medium carbon chain monomers such as methyl acrylate or isooctyl methacrylate alone can improve the adhesion between adhesive microparticles and coal / rock. This is likely because the polarity of short / medium carbon chain monomers such as methyl acrylate or isooctyl methacrylate matches that of the coal / rock surface, making them easily adsorbed and providing a basic framework for the microparticles, ensuring structural stability and preventing breakage under drilling fluid erosion. Furthermore, for coal / rock surfaces with high polarity due to the presence of clay minerals, a combination of highly hydrophobic long carbon chain dodecyl acrylate and moderately polar methyl methacrylate can be used to adjust the polarity of the microparticles, expanding the applicability range. Even if there are differences in the polarity of the coal / rock surface, a high affinity can still be maintained, thereby improving the mechanical strength of the coal / rock.

[0019] In some embodiments of this application, the functional monomer includes, but is not limited to, one or more of vinylpyrrolidone, 2-hydroxyethyl acrylate, and styrene.

[0020] In some embodiments of this application, the functional monomer is preferably three functional monomers: vinylpyrrolidone, 2-hydroxyethyl acrylate, and styrene, in a mass ratio of (0.5-2):(0.5-2):(0.5-2).

[0021] In some embodiments of this application, a combination of three functional monomers—styrene, vinylpyrrolidone, and 2-hydroxyethyl acrylate—is used to improve the affinity between microparticles and coal / rock, thereby enhancing the mechanical properties of the coal / rock while preventing sticking. This is likely because the three functional monomers have a synergistic effect: styrene enhances the hydrophobicity of the microparticles, matching the hydrophobicity of the coal / rock surface; vinylpyrrolidone contains polar pyrrolidone groups, forming hydrogen bonds with hydroxyl and carboxyl groups on the coal / rock surface; and 2-hydroxyethyl acrylate provides hydroxyl groups, further enhancing the polar bonding with the coal / rock. The combination of these three functional monomers in a specific mass ratio maximizes the synergistic effect, ensuring a strong affinity between the microparticles and the coal / rock, solving the problem of insufficient affinity of polystyrene microspheres in existing technologies, and improving the mechanical properties of the coal / rock.

[0022] In some embodiments of this application, the crosslinking monomers include, but are not limited to, one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, 1,4-butanediol diacrylate, and trimethylolpropane triacrylate.

[0023] In some embodiments of this application, the functional monomer and the crosslinking monomer may not be 0, and the mass ratio of the host monomer, the functional monomer, and the crosslinking monomer is (21-350):(10-150):1.

[0024] In some embodiments of this application, by selecting specific host monomers, functional monomers, and crosslinking monomers and adjusting their proportions, the mechanical properties of coal and rock can be improved while maintaining a durable sealing effect. This is likely due to the synergistic effect among the three monomers. The host monomer ensures continuous particle film formation and provides a basic bonding framework. The functional monomer carries polar / π-π structures such as benzene rings, hydroxyl groups, and pyrrolidones, which can form multi-point hydrogen bonds and van der Waals forces with aromatic rings, hydroxyl groups, and carboxyl groups on the coal surface, significantly improving coal affinity. The crosslinking monomer constructs a moderately crosslinked network, preventing excessive swelling and strength loss of particles in drilling fluid without causing embrittlement, ensuring that particles still have deformation-filling capabilities after entering microfractures. The combination of the three monomers achieves a dual improvement in the mechanical strength and stability of coal and rock.

[0025] In some embodiments of this application, the first initiator is a free radical initiator, including but not limited to one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the amount of the first initiator accounts for 0.1% to 4% of the total monomer mass.

[0026] In some embodiments of this application, the solvent includes, but is not limited to, one or more of base oils, alkyl or polyalkylbenzenes, aromatic esters or ethers, and alkyl esters or ethers.

[0027] In some embodiments of this application, the base oil is a long-chain alkane, including but not limited to one or more of white oil, paraffin oil, gasoline, diesel, and kerosene.

[0028] In some embodiments of this application, the alkyl or polyalkylbenzene includes, but is not limited to, one or more of toluene, xylene, diethylbenzene, trimethylbenzene, triethylbenzene, and dodecylbenzene.

[0029] In some embodiments of this application, the benzene ring-containing ester or ether includes, but is not limited to, one or more of methyl benzoate, ethyl benzoate, butyl benzoate, dibutyl phthalate, benzyl acetate, and anisole.

[0030] In some embodiments of this application, the alkyl ester or ether includes, but is not limited to, one or more of butyl acetate, isoamyl acetate, octyl acetate, dodecyl acetate, methyl palmitate, methyl oleate, dibutyl ether, and ethylene glycol dibutyl ether.

[0031] In some embodiments of this application, the aqueous phase comprises water, and the mass of the aqueous phase is 0.5-6 times the mass of the oil phase.

[0032] In some embodiments of this application, a thickener may be added to the aqueous phase, or a thickener monomer and a second initiator may be added to generate a thickener in situ to help improve the stability of the emulsion.

[0033] In some embodiments of this application, the thickener includes, but is not limited to, one or more of xanthan gum, polyacrylamide, and guar gum.

[0034] In some embodiments of this application, the thickener monomer includes, but is not limited to, one or more of acrylamide and N,N'-methylenebisacrylamide.

[0035] In some embodiments of this application, the second initiator includes, but is not limited to, one or more of potassium persulfate.

[0036] In some embodiments of this application, the amount of surfactant added is 1%-25% of the oil phase mass.

[0037] In some embodiments of this application, the surfactant, by weight, comprises 1-10 parts of a main surfactant and 0-10 parts of a co-surfactant, wherein the amount of the main surfactant added is 1-20% of the mass of the oil phase; the main surfactant includes, but is not limited to, one or more of nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants; the co-surfactant includes, but is not limited to, one or more of alkyl alcohols, ethylene glycol monoalkyl ethers, or diethylene glycol monoalkyl ethers having 3 to 8 carbon atoms.

[0038] In some embodiments of this application, the co-surfactant may not be 0, and the mass ratio of the main surfactant to the co-surfactant is (1-60):(1-10).

[0039] In some embodiments of this application, the nonionic surfactant includes, but is not limited to, one or more of the following: C12-C14 fatty alcohol polyoxyethylene ether (AEO), alkylphenol polyoxyethylene ether alkyl glycoside (APG-1214), octylphenol polyoxyethylene ether (TX), perfluorooctyl polyoxyethylene ether, dodecylphenol polyoxyethylene ether (OP-10), fatty acid sorbitan ester (Span), polyoxyethylene fatty acid sorbitan ester (Tween), and cocamidopropylamine oxide (CAO).

[0040] In some embodiments of this application, the main surfactant may be only a nonionic surfactant. When the main surfactant is only a nonionic surfactant, the main surfactant may be APG-1214, Tween 20 and Tween 80 in a mass ratio of (1-3):(1-3):1; or it may be Tween 80 and Tween 20 in a mass ratio of 1:(1-2).

[0041] In some embodiments of this application, the cationic surfactant includes, but is not limited to, octadecyltrimethylammonium chloride.

[0042] In some embodiments of this application, the main surfactant may be only a nonionic surfactant and a cationic surfactant. When the main surfactant is a nonionic surfactant and a cationic surfactant, the main surfactant may be CAO and octadecyltrimethylammonium chloride in a mass ratio of (1-1.5):1.

[0043] In some embodiments of this application, the anionic surfactant includes, but is not limited to, one or more of sodium dodecylbenzene sulfonate (SDBS / LAS), sodium secondary alkyl sulfonate (SAS), sodium dodecyl succinate sulfonate (Aerosol-OT / AOT), sodium lauryl ether sulfate (SLES) (SLES), sodium dodecyl sulfate (SDS / SLS), and sodium fatty alcohol polyoxyethylene ether sulfate (AES).

[0044] In some embodiments of this application, the main surfactant may be an anionic surfactant, which may be one of LAS, SDS, AES, etc., or a combination of LAS and SDS, with a mass ratio of (1.5-2.5):1.

[0045] In some embodiments of this application, the main surfactant may be only a nonionic surfactant and anionic surfactant. When the main surfactant is a nonionic surfactant and anionic surfactant, the main surfactant may be APG-1214, LAS and AES, with a mass ratio of (2-3):(1.5-2.5):1; or it may be LAS, Tween 20 and Tween 80, with a mass ratio of 1:(1-2):(1.5-3).

[0046] In some embodiments of this application, the zwitterionic surfactant includes, but is not limited to, one or more of oleamidopropyl betaine (OAB), cocamidopropyl betaine (CAB), sodium lauroyl sarcosinate, sodium cocoyl glutamate, alkyl hydroxyethyl imidazoline betaine, and lauryl dimethylamine oxide (OA-12).

[0047] In some embodiments of this application, the main surfactant may be a combination of nonionic surfactant and amphoteric surfactant. When the main surfactant is a nonionic surfactant or an amphoteric surfactant, the main surfactant may be Tween 20 or OAB in a mass ratio of 1:(1-2).

[0048] In some embodiments of this application, the co-surfactant includes, but is not limited to, one or more of propanol, butanol, pentanol, isoamyl alcohol, hexanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, and diethylene glycol monobutyl ether.

[0049] In some embodiments of this application, the addition of specific surfactants enables the emulsion to be uniformly dispersed in the drilling fluid, ensuring sufficient contact between the microparticles and the coal, thereby improving the performance of the coal. This may be because a suitable surfactant formulation allows the viscose to maintain its affinity for coal in the drilling fluid and minimizes demulsification during the emulsion polymerization of the preparation agent, thus improving the stability of the viscose emulsion and the mechanical strength of the coal.

[0050] In some embodiments of this application, several surfactants can be used alone or in combination as the main surfactant. Nonionic surfactants can reduce oil-water interfacial tension and ensure emulsion stability; anionic surfactants repel the negative charge on the coal and rock surface, preventing particle aggregation; amphoteric surfactants are adaptable to a wide pH range of drilling fluids, enhancing stability.

[0051] In some embodiments of this application, only nonionic surfactants can be added as the main surfactant, such as a combination of Tween and APG-1214. On the one hand, the polyoxyethylene chain of Tween and the sugar end of APG-1214 together form a hydration film on the surface of oil droplets, reducing the oil-water interfacial tension and preventing emulsion demulsification. On the other hand, the nonionic alkyl chains of both adsorb onto the coal surface through hydrophobic interactions, and the weakly polar groups form hydrogen bonds with the hydroxyl groups of the coal, while having weak polar interactions with the metal drill pipe, reducing rod adhesion. In addition, the compound system can promote the uniform dispersion of particles and their penetration into the micropores of the coal, avoid excessive surfactant masking of active sites, ensure direct contact between the adhesive and the coal, and synergistically enhance the sealing effect and the mechanical strength of the coal.

[0052] In some embodiments of this application, anionic surfactants and nonionic surfactants can be combined. The anionic surfactants carry a negative charge, which generates a moderate repulsion with the coal and rock surface, preventing excessive particle aggregation, while enhancing the spreadability of particles on the coal and rock surface, ensuring tighter pore sealing. At the same time, the nonionic surfactants provide stability and prevent demulsification. When the ratio of the two is balanced, neither excessive nonionic surfactants masking the active sites and causing a decrease in affinity, nor excessive anionic surfactants causing emulsion instability and demulsification.

[0053] In some embodiments of this application, amphoteric surfactants and nonionic surfactants can be added in combination. Amphoteric surfactants can adjust the charge within a wide pH range of drilling fluid, adapt to the charge fluctuations on the coal and rock surface, ensure that the particles can be effectively adsorbed in different coal and rock types, and ensure mechanical strength and stability.

[0054] In some embodiments of this application, an appropriate amount of co-surfactant can be added to help regulate interfacial tension, promote emulsion penetration into coal micropores, and achieve deep sealing.

[0055] One of the purposes of this application is to provide a method for preparing the viscose emulsion added to drilling fluid to enhance the strength of coal and rock. The method for preparing the viscose emulsion added to drilling fluid to enhance the strength of coal and rock includes the following steps: after mixing the oil phase evenly, adding the aqueous phase and surfactant, homogenizing, and reacting at 60-90℃ for 2-12 hours to obtain the emulsion.

[0056] In some embodiments of this application, the specific conditions for homogenization are: a stirring speed of 1000-20000 r / min and a stirring time of 0.5-15 min.

[0057] Compared with the prior art, this application achieves at least the following technical effects: The viscose emulsion prepared by this invention can seal the pores of coal and rock to prevent drilling fluid intrusion, and enhance the compressive strength of coal and rock through bonding. Furthermore, the difference in affinity between coal and metal reduces the risk of rod sticking. Mixing the prepared viscose emulsion with drilling fluid and soaking the coal and rock can largely maintain the original strength of the coal and rock, solving problems such as wellbore instability and stuck drill bits during coal gas drilling.

[0058] This invention improves the mechanical properties of coal and rock by controlling the proportion of the three monomers in the oil phase.

[0059] This invention improves the mechanical properties of coal and rock by selecting main monomers, functional monomers, and crosslinking monomers with high affinity for coal and adjusting their proportions, while maintaining a long-lasting sealing effect.

[0060] The adhesive emulsion prepared by this invention can achieve different affinity for coal and metal, adhering to coal while having weak adhesion to metal, thus preventing risks such as sticking to rods.

[0061] This invention, by adding specific surfactants, enables the emulsion to be uniformly dispersed in drilling fluid, maintains its affinity for coal, and minimizes demulsification during the emulsion polymerization of the preparation of the agent.

[0062] This invention uses a water-in-oil polymer emulsion made from adhesive to be used in drilling fluid, which enhances the strength of coal and rock while preventing it from being invaded by drilling fluid. Attached Figure Description

[0063] Figure 1 This is the infrared spectrum of the viscose emulsion prepared in Example 1 of the present invention.

[0064] Figure 2 It is the viscose emulsion prepared in Example 1 of this invention. 1 HNMR image.

[0065] Figure 3 This is the infrared spectrum of the viscose emulsion prepared in Example 2 of the present invention.

[0066] Figure 4 It is the viscose emulsion prepared in Example 2 of this invention. 1 HNMR image.

[0067] Figure 5 This is the infrared spectrum of the viscose emulsion prepared in Example 3 of the present invention.

[0068] Figure 6 It is the viscose emulsion prepared in Example 3 of this invention. 1 HNMR image.

[0069] Figure 7 This is the infrared spectrum of the viscose emulsion prepared in Example 4 of the present invention.

[0070] Figure 8 It is the viscose emulsion prepared in Example 4 of this invention. 1 HNMR image.

[0071] Figure 9 This is the infrared spectrum of the viscose emulsion prepared in Example 5 of the present invention.

[0072] Figure 10 It is the viscose emulsion prepared in Example 5 of this invention. 1 HNMR image.

[0073] Figure 11 This is the infrared spectrum of the viscose emulsion prepared in Example 6 of the present invention.

[0074] Figure 12 It is the viscose emulsion prepared in Example 6 of this invention. 1 HNMR image.

[0075] Figure 13 This is the infrared spectrum of the viscose emulsion prepared in Example 7 of the present invention.

[0076] Figure 14 It is the viscose emulsion prepared in Example 7 of this invention. 1 HNMR image.

[0077] Figure 15 This is the infrared spectrum of the viscose emulsion prepared in Example 8 of the present invention.

[0078] Figure 16 It is the viscose emulsion prepared in Example 8 of this invention. 1 HNMR image.

[0079] Figure 17 This is the infrared spectrum of the viscose emulsion prepared in Example 9 of the present invention.

[0080] Figure 18 It is the viscose emulsion prepared in Example 9 of this invention. 1 HNMR image.

[0081] Figure 19 These are photographs of the emulsions prepared in Examples 1-9 of this invention.

[0082] Figure 20 The results are the affinity test results of the oil phase adhesive prepared in Example 1 of this invention with various substances. From left to right, they are: iron nuts stuck in water, pebbles stuck in water, quartz sand stuck in water, coal blocks stuck in water, and coal blocks stuck in white oil. Detailed Implementation

[0083] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0084] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. All reagents and instruments used herein are commercially available, and the characterization methods involved are described in relevant prior art and will not be repeated herein.

[0085] All raw materials used in this invention are commercially available, specifically: APG-1214, from Linyi Lusen Chemical Co., Ltd.

[0086] Twain 20, from Guangdong Runhua Chemical Co., Ltd.

[0087] Twain 80, from Guangdong Runhua Chemical Co., Ltd.

[0088] Kerosene, from Anaiji Chemical.

[0089] Xanthan gum, from Anhui Zhonghong Bioengineering Co., Ltd.

[0090] CAO comes from Linyi Lusen Chemical Co., Ltd.

[0091] TX-100 is from Shandong Kunteng Chemical Co., Ltd.

[0092] Span 80, from Guangdong Runhua Chemical Co., Ltd.

[0093] Paraffin oil, sourced from Hebei Wantai Chemical Co., Ltd.

[0094] Nano-silica, sourced from Renqiu Deli Petroleum Additives Co., Ltd.

[0095] Ultrafine calcium carbonate powder, sourced from Renqiu Deli Petroleum Additives Co., Ltd.

[0096] Perfluorooctyl polyoxyethylene ether, from Wuhan Kemic Biomedical Technology Co., Ltd.

[0097] OP-10, from Linyi Lusen Chemical Co., Ltd.

[0098] The raw materials in the conventional drilling fluid are sourced from the following sources: bentonite, xanthan gum XC, PAC-LV, coating inhibitor, NH4-HPAN, filtration loss reducer NAT-20, white asphalt NFA-25, emulsified asphalt, ultrafine calcium, micro-nano plugging agent, polyol, and liquid lubricant, all from Renqiu Deli Petroleum Additives Co., Ltd.; barite from Tianjin Huasheng Chemical Reagent Co., Ltd.

[0099] Example 1 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: 29.3g ethyl acrylate, 8g vinylpyrrolidone, 7g 2-hydroxyethyl acrylate, 5g styrene, 0.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 70g diethylbenzene were mixed thoroughly. Then, 170g water, 4g APG-1214, 4g Tween 20, and 2g Tween 80 were added. The mixture was homogenized at 10000 rpm for 5 minutes. After homogenization, the mixture was poured into a reaction flask and reacted at 70℃ for 10 hours. After the reaction was complete, the emulsion was poured out of the reaction flask. A sample was dropped onto a petri dish, dried at 50℃, and then measured using infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 1 and Figure 2 .

[0100] Example 2 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: 32.3g dodecyl acrylate, 7g styrene, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 1.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 60g dodecylbenzene were mixed thoroughly. Then, 170g water, 4g APG-1214, 3g LAS, 1.5g AES, and 0.5g ethylene glycol monoethyl ether were added. The mixture was homogenized at 5000 rpm for 10 minutes. After homogenization, the mixture was poured into a reaction flask and reacted at 65℃ for 12 hours. After the reaction was complete, the emulsion was poured out of the reaction flask. A sample was dropped onto a petri dish, dried at 50℃, and then measured using infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 3 and Figure 4 .

[0101] Example 3 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: 24.3g dodecyl acrylate, 5g methyl methacrylate, 10g styrene, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 0.5g ethylene glycol dimethacrylate, 1g azobisisobutyronitrile, and 70g ethylene glycol dibutyl ether were mixed thoroughly. Then, 120g water, 0.5g acrylamide, 0.1g N,N'-methylenebisacrylamide, 0.02g potassium persulfate, 4g Tween 80, 3g Tween 20, and 2g LAS were added. The mixture was homogenized at 1000 rpm for 15 minutes using a mechanical stirrer. After homogenization, the mixture was poured into a reaction flask and reacted at 85℃ for 2 hours. After the reaction was complete, the emulsion was poured out of the reaction flask. A sample was dropped onto a petri dish, dried at 50℃, and then measured using infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 5 and Figure 6 .

[0102] Example 4 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: 29.3g of isooctyl methacrylate, 8g of vinylpyrrolidone, 7g of 2-hydroxyethyl acrylate, 5g of styrene, 0.5g of 1,4-butanediol diacrylate, 0.2g of azobisisobutyronitrile, and 70g of methyl oleate were mixed thoroughly. Then, 60g of water, 0.2g of polyacrylamide, 8g of Tween 20, 15g of 30% OAB, and 1g of ethylene glycol monobutyl ether were added. The mixture was homogenized at 5000 rpm for 6 minutes. After homogenization, the mixture was poured into a reaction flask and reacted at 70℃ for 8 hours. After the reaction was complete, the emulsion was poured out of the reaction flask. A sample was dropped onto a petri dish, dried at 50℃, and then measured using infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 7 and Figure 8 .

[0103] Example 5 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 24.3g vinyl acetate, 10g ethyl acrylate, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 5g styrene, 0.1g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 80g butyl acetate thoroughly. Then add 110g water, 1.3g SDS, and 13g octanol. Homogenize at 20000 rpm for 5 minutes. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 10 hours. After the reaction is complete, pour the emulsion out of the reaction flask. Take a sample, drop it onto a petri dish, dry it at 50℃, and then measure the infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 9 and Figure 10 .

[0104] Example 6 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: 39.9g of ethyl acrylate, 10g of methyl methacrylate, 0.05g of trimethylolpropane triacrylate, and 0.05g of azobisisobutyronitrile were mixed thoroughly. Then, 80g of water, 0.2g of guar gum, 5g of LAS, and 2.5g of SDS were added. The mixture was homogenized at 1000 rpm for 15 minutes. After homogenization, the mixture was poured into a reaction flask and reacted at 70℃ for 12 hours. After the reaction was complete, the emulsion was poured out of the reaction flask. A sample was dropped onto a petri dish, dried at 50℃, and then measured using infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 11 and Figure 12 .

[0105] Example 7 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 26g ethyl acrylate, 23g styrene, 0.5g 1,4-butanediol diacrylate, 0.5g benzoyl peroxide, and 92g butyl benzoate thoroughly. Then add 110g water, 0.3g xanthan gum, 12g LAS, and 0.5g propanol. Homogenize at 15000 rpm for 0.5 minutes. After homogenization, pour the mixture into a reaction flask and react at 75℃ for 12 hours. After the reaction is complete, pour the emulsion out of the reaction flask. Take a sample, drop it onto a petri dish, dry it at 50℃, and then measure the infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 13 and Figure 14 .

[0106] Example 8 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 48g ethyl acrylate, 1.5g 1,4-butanediol diacrylate, 0.5g azobisisobutyronitrile, and 70g white oil until homogeneous. Then add 720g water, 10g CAO, and 8g octadecyltrimethylammonium chloride. Homogenize at 7000 rpm for 6 minutes. After homogenization, pour the mixture into a reaction flask and react at 65℃ for 10 hours. After the reaction is complete, pour the emulsion out of the reaction flask. Take a sample, drop it onto a petri dish, dry it at 50℃, and then measure the infrared spectroscopy. 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 15 and Figure 16 .

[0107] Example 9 This embodiment provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 30g ethyl acrylate, 20g methyl methacrylate, 2g azobisisobutyronitrile (AIB), and 96g dibutyl ether until homogeneous. Then add 200g water, 17.5g Tween 20, 12g Tween 80, and 0.5g octanol. Homogenize at 5000 rpm for 8 minutes. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 12 hours. After the reaction is complete, pour the emulsion out of the reaction flask. Take a sample, drop it onto a petri dish, dry it at 50℃, and then measure the infrared spectroscopy and... 1 ¹H NMR (with CDCl₃ as the deuterated solvent), see [references]. Figure 17 and Figure 18 .

[0108] Photographs of the emulsions prepared in Examples 1-9 are shown below. Figure 19 .

[0109] Comparative Example 1 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 39.5g styrene, 5g vinylpyrrolidone, 5g butyl acrylate, 0.5g azobisisobutyronitrile, and 50g paraffin oil until homogeneous. Then add 120g water, 0.5g acrylamide, 0.1g N,N'-methylenebisacrylamide, 0.02g potassium persulfate, 1.5g Span 80, and 5g Tween 80. Homogenize at 5000 rpm for 6 minutes. After homogenization, pour into a reaction flask and react at 70℃ for 12 hours to obtain the final product.

[0110] Comparative Example 2 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 19.5g butyl acrylate, 15g styrene, 10g vinylpyrrolidone, 5g hydroxyethyl acrylate, 0.5g azobisisobutyronitrile, and 50g paraffin oil until homogeneous. Then add 120g water, 3g APG-1214, and 3.5g Tween 80. Homogenize at 5000r / min for 6min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 12h to obtain the final product.

[0111] Comparative Example 3 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 19.5g acrylamide, 5g styrene, 5g ethyl acrylate, 10g vinylpyrrolidone, 10g hydroxyethyl acrylate, 0.5g azobisisobutyronitrile, and 100g ethanol until homogeneous. Then add 10g water and 0.5g APG-1214, and homogenize using a homogenizer at 1000r / min for 1min. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 12h to obtain the final product.

[0112] Comparative Example 4 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Add 50g paraffin oil, 50g water, 0.5g xanthan gum, 1.5g APG-1214, and 1g Tween 80 to a beaker and homogenize using a homogenizer at 5000 rpm for 3 minutes.

[0113] Comparative Example 5 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Add 10g of nano silica, 10g of ultrafine calcium carbonate powder, 5g of dodecyltrimethylammonium chloride, 10g of potassium perfluorobutyl sulfonate, 5g of OP-10, 120g of water, and 1g of xanthan gum to a beaker, and homogenize using a homogenizer at 1000r / min for 3min to obtain the final product.

[0114] Comparative Example 6 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 19.3g ethyl acrylate, 10g vinylpyrrolidone, 10g 2-hydroxyethyl acrylate, 10g styrene, 0.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 70g diethylbenzene until homogeneous. Then add 110g water, 4g APG-1214, 4g Tween 20, and 2g Tween 80. Homogenize at 10000r / min for 5min. After homogenization, pour into a reaction flask and react at 70℃ for 10h to obtain the final product.

[0115] Comparative Example 7 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 29.3g ethyl acrylate, 8g vinylpyrrolidone, 7g 2-hydroxyethyl acrylate, 5g styrene, 2.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 70g diethylbenzene until homogeneous. Then add 110g water, 4g APG-1214, 4g Tween 20, and 2g Tween 80. Homogenize at 10000r / min for 5min. After homogenization, pour into a reaction flask and react at 70℃ for 10h to obtain the final product.

[0116] Comparative Example 8 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 29.3g ethyl acrylate, 8g vinylpyrrolidone, 7g 2-hydroxyethyl acrylate, 5g styrene, 0.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 160g diethylbenzene until homogeneous. Then add 110g water, 4g APG-1214, 4g Tween 20, and 2g Tween 80. Homogenize at 10000r / min for 5min. After homogenization, pour into a reaction flask and react at 70℃ for 10h to obtain the final product.

[0117] Comparative Example 9 This comparative example provides a method for preparing a viscose emulsion that can be added to drilling fluid to enhance the strength of coal and rock. The specific steps are as follows: Mix 29.3g ethyl acrylate, 8g vinylpyrrolidone, 7g 2-hydroxyethyl acrylate, 5g styrene, 0.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 70g diethylbenzene until homogeneous. Then add 110g water, 0.4g APG-1214, 0.4g Tween 20, and 0.2g Tween 80. Homogenize at 10000r / min for 5min. After homogenization, pour into a reaction flask and react at 70℃ for 10h.

[0118] Performance testing The viscose emulsion prepared above was added to a conventional water-based drilling fluid at a feed concentration of 2% (the drilling fluid formulation was: water, 1 L; calcium sulfate dihydrate 5.86 g; calcium chloride, 24.68 g; magnesium chloride hexahydrate, 5.52 g; sodium chloride, 29.86 g; potassium chloride, 0.596 g; bentonite, 35 g; xanthan gum XC, 1.5 g; PAC-LV, 3.5 g; coating inhibitor, 12.5 g; NH4-HPAN, 7.5 g; filtration loss reducer NAT-20, 25 g; white asphalt NFA-25, 25 g; emulsified asphalt, 25 g; ultrafine calcium, 40 g; micro / nano plugging agent, 15 g; polyol, 15 g; liquid lubricant, 65 g; barite, 40 g). g. Add all raw materials to a beaker and stir mechanically at 1500 rpm for 3 hours to obtain the drilling fluid. After soaking a 2.5cm*2.5cm cylindrical coal sample for 1 hour, test the compressive strength of the coal. The results are shown in Table 1. The initial compressive strength of the unsoaked 2.5cm*2.5cm cylindrical coal sample was 30.98 MPa; after soaking the 2.5cm*2.5cm cylindrical coal sample in conventional water-based drilling fluid without this reagent for 1 hour, the compressive strength was 17.36 MPa.

[0119] Table 1 Summary of Coal and Rock Compressive Strength Results

[0120] As shown in Table 1, all examples used a viscose emulsion system with high affinity for coal and a specific surfactant system. The viscose emulsions prepared and applied to drilling fluids significantly improved the compressive strength of coal and rock. Comparative Example 1 was a microsphere emulsion mainly composed of polystyrene, representing the first type of scheme in the background art; Comparative Example 2 had an excess of functional monomers; Comparative Example 3 used acrylamide as the main monomer and added a thickener to inhibit coal powdering, representing the second type of scheme in the background art; Comparative Example 4 had no monomers; Comparative Example 5 consisted of inorganic nanoparticles and surfactants, similar to the third type of scheme in the background art; Comparative Example 6 had a ratio of main monomers to functional monomers that did not conform to the ratio range of this patent; Comparative Example 7 had an excessively high proportion of crosslinking monomers; Comparative Example 8 had an excessively low monomer content and an excessively high solvent content in the oil phase; Comparative Example 9 had an excessively low amount of surfactant. The compressive strength of coal and rock in the comparative examples was worse than that in the examples, and Comparative Example 9 suffered severe demulsification, making it impossible to test its compressive strength. This indicates that the viscose emulsion prepared by this invention can seal the pores of coal and rock to prevent drilling fluid intrusion and enhance the compressive strength of coal and rock through bonding.

[0121] The agent obtained in Case 1 was demulsified by freezing and thawing, causing the oil phase adhesive to precipitate and clump together. The affinity and adhesion of the oil phase adhesive to iron nuts, pebbles, quartz sand, and coal lumps were tested. The oil phase adhesive was used to adhere iron nuts (1.58g), pebbles (3.35g), quartz sand, and coal lumps (4.48g) to water, respectively, and coal lumps (5.53g) to white oil. The results are shown in [Figure number missing]. Figure 20 .from Figure 20 It can be seen that the oil-phase adhesive prepared in Example 1 of this invention cannot pick up iron nuts, pebbles, or quartz sand from water, but it can pick up heavier coal and rock blocks from water or white oil. This indicates that the oil-phase adhesive prepared in Example 1 of this invention has the characteristics of not sticking to iron, pebbles, or quartz sand, and has high affinity and high interfacial tolerance for coal and rock, and can adhere to and lift coal and rock from water or white oil.

[0122] The applicant declares that this application illustrates, through the above embodiments, a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, and its preparation method. However, this application is not limited to the above embodiments, i.e., it does not mean that this application must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the raw materials of this application, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

[0123] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0124] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

Claims

1. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 29.3g of ethyl acrylate, 8g of vinylpyrrolidone, 7g of 2-hydroxyethyl acrylate, 5g of styrene, 0.5g of ethylene glycol dimethacrylate, 0.2g of azobisisobutyronitrile, and 70g of diethylbenzene evenly. Then add 170g of water, 4g of APG-1214, 4g of Tween 20, and 2g of Tween 80. Homogenize using a homogenizer at 10000r / min for 5min. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 10h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

2. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 32.3g dodecyl acrylate, 7g styrene, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 1.5g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 60g dodecylbenzene evenly. Then add 170g water, 4g APG-1214, 3g LAS, 1.5g AES, and 0.5g ethylene glycol monoethyl ether. Homogenize at 5000r / min for 10min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 65℃ for 12h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

3. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 24.3g dodecyl acrylate, 5g methyl methacrylate, 10g styrene, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 0.5g ethylene glycol dimethacrylate, 1g azobisisobutyronitrile, and 70g ethylene glycol dibutyl ether evenly. Then add 120g water, 0.5g acrylamide, 0.1g N,N'-methylenebisacrylamide, 0.02g potassium persulfate, 4g Tween 80, 3g Tween 20, and 2g LAS. Homogenize using a mechanical stirrer at 1000r / min for 15min. After homogenization, pour into a reaction flask and react at 85℃ for 2h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

4. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 29.3g of isooctyl methacrylate, 8g of vinylpyrrolidone, 7g of 2-hydroxyethyl acrylate, 5g of styrene, 0.5g of 1,4-butanediol diacrylate, 0.2g of azobisisobutyronitrile, and 70g of methyl oleate evenly. Then add 60g of water, 0.2g of polyacrylamide, 8g of Tween 20, 15g of 30% OAB, and 1g of ethylene glycol monobutyl ether. Homogenize at 5000r / min for 6min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 8h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

5. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 24.3g vinyl acetate, 10g ethyl acrylate, 5g vinylpyrrolidone, 5g 2-hydroxyethyl acrylate, 5g styrene, 0.1g ethylene glycol dimethacrylate, 0.2g azobisisobutyronitrile, and 80g butyl acetate evenly. Then add 110g water, 1.3g SDS, and 13g octanol. Homogenize at 20,000 rpm for 5 minutes. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 10 hours. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

6. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 39.9g of ethyl acrylate, 10g of methyl methacrylate, 0.05g of trimethylolpropane triacrylate, and 0.05g of azobisisobutyronitrile evenly. Then add 80g of water, 0.2g of guar gum, 5g of LAS, and 2.5g of SDS. Homogenize at 1000r / min for 15min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 12h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

7. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 26g ethyl acrylate, 23g styrene, 0.5g 1,4-butanediol diacrylate, 0.5g benzoyl peroxide, and 92g butyl benzoate evenly. Then add 110g water, 0.3g xanthan gum, 12g LAS, and 0.5g propanol. Homogenize at 15000r / min for 0.5min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 75℃ for 12h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

8. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 48g of ethyl acrylate, 1.5g of 1,4-butanediol diacrylate, 0.5g of azobisisobutyronitrile, and 70g of white oil evenly. Then add 720g of water, 10g of CAO, and 8g of octadecyltrimethylammonium chloride. Homogenize at 7000r / min for 6min using a homogenizer. After homogenization, pour the mixture into a reaction flask and react at 65℃ for 10h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

9. A method for preparing a viscose emulsion added to drilling fluid to enhance the strength of coal and rock, characterized in that, The specific steps are as follows: Mix 30g ethyl acrylate, 20g methyl methacrylate, 2g azobisisobutyronitrile, and 96g dibutyl ether evenly, then add 200g water, 17.5g Tween 20 and 12g Tween 80, and 0.5g octanol. Homogenize using a homogenizer at 5000r / min for 8min. After homogenization, pour the mixture into a reaction flask and react at 70℃ for 12h. After the reaction is complete, pour the emulsion out of the reaction flask to obtain the final product.

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