A composition, micro-nano fiber cleaning agent and its preparation method and application

Abstract

The present application relates to a composition, a micro-nano fiber cleaning agent and a preparation method and application thereof. The composition comprises a first homopolymer grafted polyester micro fiber, a second homopolymer grafted nano cellulose and a crosslinking agent. The preparation method of the micro-nano fiber cleaning agent comprises the following steps: S1. reacting a raw material system comprising the composition and a solvent to obtain a reaction product containing the micro-nano fiber cleaning agent; and optionally, S2. removing the solvent contained in the reaction product to obtain the micro-nano fiber cleaning agent. The molecular weight of the micro-nano fiber cleaning agent is 60000-90000. The present application also comprises the application of the micro-nano fiber cleaning agent in drilling fluid, especially in drilling cuttings cleaning agent. The micro-nano fiber cleaning agent of the present application learns from the method of bionics and designs a "stick + fluff" structure, which has a very strong adsorption and cleaning effect on small solid particles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield drilling fluid, in particular to a composition for preparing a micro-nano fiber cleaning agent and a cross-linking compound prepared according to the composition, a micro-nano fiber cleaning agent and a preparation method and application thereof. BACKGROUND

[0002] In the process of oil and gas field exploration and development, people initially used straight well drilling, but as the drilling depth becomes deeper and the complexity of the formation becomes higher, people began to use directional wells, large displacement wells and horizontal wells and other technologies for development, but in the process of drilling these complex wells, rock debris beds often appear, when rock debris beds appear, it may cause tripping resistance, pump blocking and other accidents, and in severe cases, it may cause well collapse and sticking accidents. For conventional wellbores, a viscosity and shear raising agent needs to be added to improve the viscosity and shear force of the drilling fluid, thereby improving its ability to carry cuttings. Initially, bentonite was used as a viscosity and shear raising agent, but later it was found that the shear raising effect of this treatment agent was limited and the temperature resistance was poor. Also, some synthetic polymers can be added to improve the viscosity of the drilling fluid, but this approach may deteriorate the overall performance of the drilling fluid, leading to poor adjustment in the later stage. Therefore, recently, people have begun to propose the use of thick slurry plugs to remove rock debris beds. In the thick slurry, a certain material with structural strength needs to be added. Cyangshun et al. (CN201010552940.3) first introduced ultra-short fibers into the drilling fluid, which have a length of 1-5 mm and a diameter of 100-500 μm, and have a certain structural effect in the drilling fluid. Subsequently, Yu Lei et al. (CN201210578515.0) first used ultra-short fibers in wellbore cleaning fluid, but the content of ultra-short fibers in the formula was less than 3.0%, and the plug removal capacity was limited, mainly relying on the polymer in the formula to thicken. Cai Yongmao et al. (CN201310628189.4) also proposed a method of using ultra-short fibers for oil layer profile control and plugging, which can form a suspended plugging agent with polymer aqueous solution and ternary liquid, but this method does not mention the interaction between micro fibers and nano fibers. Nanocellulose fiber is a new material that has emerged in recent years and can be prepared by acid hydrolysis, enzymatic hydrolysis and mechanical degradation. Recently, Liu Juyi et al. (CN201711090694.2) used cellulose nanofiber as a drilling fluid flow pattern regulator.

[0003] Polyester fiber is a commonly used chemical fiber, commonly known as polyester, which is composed of short aliphatic hydrocarbon chains, ester groups, benzene rings and terminal alcohol hydroxyl groups. This polymer rarely uses oilfield treatment agents. SUMMARY

[0004] In order to efficiently remove the rock debris bed often appearing in the lower part of the complex structure well, and solve the problem of limited structural strength and poor temperature resistance of the conventional cleaning agent, the application designs a "stick + fluff" structure by referring to the method of bionics. The structure has a strong adsorption and cleaning effect on small solid particles. The application provides a preparation method of the micro-nano fiber cleaning agent. First, a second homopolymer grafted nanocellulose is prepared. Then, a first homopolymer grafted polyester microfiber is prepared. Finally, the first homopolymer grafted polyester microfiber is used as a "stick", and the second homopolymer grafted nanocellulose is crosslinked to the "stick" through the micro-crosslinking of acrylamide to form "fluff", so that the bionic micro-nano fiber with the "stick + fluff" structure is finally formed. In addition, the application also provides a micro-nano fiber cleaning agent which has a remarkable effect when used in the drilling debris cleaning agent.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the application provides a composition for preparing a micro-nano fiber cleaning agent. The composition includes the following components in parts by weight:

[0006] 70-76 parts of first homopolymer grafted polyester microfiber; preferably 72-74.5 parts;

[0007] 22-28 parts of second homopolymer grafted nanocellulose; preferably 23.5-25.5 parts;

[0008] 1-3 parts of crosslinking agent; preferably 1.5-2.5 parts.

[0009] In some embodiments of the application, the first homopolymer and the second homopolymer are the same or different, and each is independently derived from monomer A. The diameter of the polyester microfiber is 1-5 μm, and the length is 500-2000 μm. The diameter of the nanocellulose is 10-20 nm, and the length is 10-100 μm.

[0010] According to the application, preferably, the weight average molecular weight of the first homopolymer is 200-500; and / or the weight average molecular weight of the second homopolymer is 100-200.

[0011] According to the application, the polyester microfiber can be referred to as a polyester fiber.

[0012] In some embodiments of the application, the monomer A is selected from the monomers having the structure shown in formula (I);

[0013]

[0014] In formula (I), R1 is selected from hydrogen, C1-C5 linear alkyl, C3-C5 branched alkyl and C3-C5 cyclic alkyl, preferably one of hydrogen or C1-C5 linear alkyl, more preferably hydrogen, methyl or ethyl.

[0015] In some embodiments of the present application, the grafting rate of the first homopolymer in the first homopolymer grafted polyester microfiber is 30%-50%; and / or the grafting rate of the second homopolymer in the second homopolymer grafted nanocellulose is 40%-60%.

[0016] According to the present application, the acid-base titration method is used to determine the grafting rate of the first homopolymer and the second homopolymer.

[0017] According to the present application, the calculation method of the grafting rate is: grafting rate % = grafted monomer mass / (grafted monomer mass + ungrafted monomer homopolymer mass) * 100%. In the present application, the ungrafted monomer homopolymer mass can be obtained by centrifugal separation of the remaining solution after the preparation is completed and the product is separated, and then the mass is determined by a spectrometer and / or a Ubbelohde viscometer to determine the viscosity average molecular weight. For example, in the first homopolymer grafted polyester microfiber, the grafting rate % of the first homopolymer = the mass of the first homopolymer grafted onto the polyester microfiber / (the mass of the first homopolymer grafted onto the polyester microfiber + the mass of the ungrafted monomer A homopolymer) * 100%.

[0018] In some embodiments of the present application, the polyester microfiber is a polydiacid-diol ester microfiber, preferably the polydiacid-diol ester is polyethylene terephthalate, and the general formula thereof is preferably HO-H2C-H2C-O[-OC-Ph-COOCH2CH2O-] n H, and the number average molecular weight is preferably 22000-25000.

[0019] In some embodiments of the present application, the nanocellulose is extracted from one or more of sugarcane residue, cotton, cotton linter, wheat straw and mulberry bark.

[0020] According to the present application, the sugarcane residue is the residue after the juice is extracted from sugar cane, and the main components are vitamins, fats, proteins, organic acids, calcium, iron and other substances; the cotton, cotton linter, wheat straw and mulberry bark can all be conventional products obtained through commercial channels.

[0021] In some embodiments of the present application, the extraction method of the nanocellulose comprises the steps of:

[0022] S211. Contacting one or more of sugarcane residue, cotton, cotton linter, wheat straw and mulberry bark with sulfuric acid to obtain an acid hydrolysis system;

[0023] S212. centrifuging and dialyzing the acidolysis system to obtain the nanocellulose.

[0024] In some embodiments of the present application, in step S211, the sulfuric acid is a 64wt%-66wt% sulfuric acid solution; the mass ratio of the bagasse to the sulfuric acid is (600-800):(1800-2300); the contacting condition includes: temperature of 60°C-80°C, time of 3-5h.

[0025] In some embodiments of the present application, in step S212, the supernatant is removed from the centrifuged system until the pH of the centrifuged system is 3.0-4.0; then the centrifuged system is dialyzed until the pH of the dialyzed system is 7.0-8.0.

[0026] According to the present application, the centrifuging condition in step S212 is not fixed or strictly limited, and can be flexibly selected by those skilled in the art according to the actual situation.

[0027] According to the present application, the dialyzing condition in step S212 is not fixed or strictly limited, and can be flexibly selected by those skilled in the art according to the actual situation.

[0028] In some embodiments of the present application, the crosslinking agent is selected from one or more of aluminum chloride, aluminum bromide, zirconium chloride, zirconium bromide, iron chloride and iron bromide, preferably selected from one or more of aluminum chloride, aluminum bromide, iron chloride and iron bromide, and more preferably aluminum chloride and / or iron chloride.

[0029] The second aspect of the present application provides a micro-nano fiber cleaning agent prepared by using the composition of the first aspect of the present application, wherein the micro-nano fiber cleaning agent has a weight average molecular weight of 60000-90000.

[0030] According to the present application, the weight average molecular weight of the micro-nano fiber cleaning agent is measured by gel chromatography.

[0031] The third aspect of the present application provides a preparation method of a micro-nano fiber cleaning agent, comprising the steps of:

[0032] S1. reacting a raw material system comprising the composition of any one of claims 1-3 and a solvent to obtain a reaction product containing a micro-nano fiber cleaning agent.

[0033] In some embodiments of the present application, the preparation method further comprises an optional step of:

[0034] S2. removing the solvent contained in the reaction product to obtain the micro-nano fiber cleaning agent.

[0035] In some embodiments of the present application, the solvent in step S1 is selected from one or more of acetone, isopropyl alcohol and propanol, preferably acetone.

[0036] According to the present application, the amount of solvent added in step S11 is not fixed or strictly limited, and can be flexibly selected by those skilled in the art according to the actual situation.

[0037] In some embodiments of the present application, the reaction conditions in step S1 include a temperature of 80-100℃ and a time of 20-40 min.

[0038] In some embodiments of the present application, the method for preparing the micro-nano fiber cleaning agent can comprise the steps of:

[0039] (1) adding 800-1200 g of first homopolymer grafted polyester microfiber, 280-380 g of second homopolymer grafted nanocellulose and 2000-2500 g of acetone into a high-pressure reaction kettle in sequence, increasing the temperature of the reaction kettle to 80-100℃, and stirring at a speed of 300 rpm for 30-50 min;

[0040] (2) adding 26-32 g of a crosslinking agent into the above reaction kettle, and performing micro-crosslinking reaction for 20-40 min;

[0041] (3) after the reaction is completed, transferring the system into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent, and the obtained product is a biomimetic micro-nano fiber cleaning agent for drilling fluid.

[0042] The present application does not have a fixed or strict limitation on the "low temperature" in step (3), which is preferably controlled to be in the range of 4-10℃ for rotary evaporation.

[0043] The present application does not have special limitations on the method and conditions of rotary evaporation in step (3), and those skilled in the art can select appropriate processes according to the actual situation.

[0044] In some embodiments of the present application, the method for preparing the first homopolymer grafted polyester microfiber comprises the steps of:

[0045] S11. performing swelling reaction on the reaction system comprising polyester microfiber and solvent to obtain swollen polyester microfiber;

[0046] S12. contacting the swollen polyester microfiber, acetone and benzophenone to obtain a dispersed system;

[0047] S13. performing grafting reaction on the raw material system comprising the dispersed system and monomer A to obtain reaction product I containing first homopolymer grafted polyester microfiber; and optionally step,

[0048] S14. After the treatment of heating and removing the residual solvent of the reactant I, the first homopolymer grafted polyester microfiber is obtained.

[0049] According to the present application, monomer A can be polymerized into the first homopolymer first, and then grafted onto the polyester microfiber to form the first homopolymer grafted polyester microfiber; or monomer A or polymer with smaller molecular weight can be grafted onto the polyester microfiber first, and then other monomer A molecules or polymer after the homopolymerization of monomer A are polymerized with the molecules or polymer which have been grafted onto the polyester microfiber to form the first homopolymer grafted polyester microfiber. In common words, monomer A can be "grown" first, and then grafted onto the polyester microfiber; or monomer A or polymer with smaller molecular weight can be grafted onto the polyester microfiber first, and then "grown" slowly. Therefore, there is no fixed or strict limitation on the adding ratio of the polyester microfiber and monomer A in the present application.

[0050] In some embodiments of the present application, in step S11, the solvent is m-cresol; the mass ratio of the polyester microfiber to the solvent is (12-15):(20-25); and the mixing conditions of the polyester microfiber and the solvent include that the temperature is 120-150°C, the stirring speed is 250-350 rpm, and the time is 30-50 min.

[0051] In some embodiments of the present application, in step S12, the mass ratio of the swelled polyester microfiber, acetone and benzophenone is (8-12):(10-12):(8-10); and the dispersion conditions include that the temperature is 60-80°C, the stirring speed is 550-650 rpm, and the time is 30-50 min.

[0052] In some embodiments of the present application, in step S13, the raw material system further comprises an initiator and a chain transfer agent; preferably, the initiator is selected from one or two of potassium persulfate, ammonium persulfate, sodium persulfate, sodium sulfite, potassium nitrite and cerium nitrate; preferably, the chain transfer agent is selected from one or two of 2-mercaptoethylamine, β-mercaptoethanol and dodecyl mercaptan; preferably, the mass ratio of the initiator to monomer A is (0.25-1):1, and the mass ratio of the chain transfer agent to monomer A is (0.125-0.4):1.

[0053] In some embodiments of the present application, the preparation method of the first homopolymer grafted polyester microfiber can comprise the following steps:

[0054] (1) adding 1200-1500 g polyester micron fibers and 2000-2500 g m-cresol into a high-pressure reactor in sequence, increasing the temperature of the system to 120-150 °C, stirring at a speed of 300 rpm, and swelling for 30-50 min, then washing with deionized water several times, and naturally drying to obtain swollen polyester micron fibers;

[0055] (2) adding 800-1200 g swollen polyester micron fibers, 1000-1200 g acetone, and 800-1000 g benzophenone into another high-pressure reactor in sequence, increasing the temperature of the system to 60-80 °C, stirring at a speed of 600 rpm, and dispersing for 30-50 min;

[0056] (3) introducing high-purity nitrogen into the reactor in (2) above to remove oxygen for 30 min, then adding 40-80 g acrylamide and 20-40 g initiator in sequence, and polymerizing for 30-50 min, then adding 10-16 g chain transfer agent to end the reaction;

[0057] (4) after the reaction is completed, taking out the system after the reaction, and dispersing it into deionized water, boiling, and then transferring into a rotary evaporator to evaporate the remaining solvent at low temperature, and the obtained product is the first homopolymer grafted polyester micron fiber.

[0058] According to the present application, boiling in step (4) can remove the generated acrylamide homopolymer.

[0059] The present application does not have fixed or strict restrictions on the "low temperature" in step (4), which is preferably controlled to be in the range of 4-10 °C for rotary evaporation.

[0060] The present application does not have special restrictions on the method and conditions of rotary evaporation in step (4), and those skilled in the art can select appropriate processes according to actual conditions.

[0061] In some embodiments of the present application, the method for preparing the second homopolymer grafted nanocellulose comprises the steps of:

[0062] S21. performing a grafting reaction on a raw material system comprising the nanocellulose and monomer A to obtain a reaction I containing the second homopolymer grafted nanocellulose; and

[0063] Optionally, S22. filtering, washing, and removing the solvent from the reaction I to obtain the second homopolymer grafted nanocellulose.

[0064] According to the present application, as above, monomer A can be first polymerized into a second homopolymer, and then grafted onto nanocellulose to form a second homopolymer grafted nanocellulose; or monomer A or a polymer with a smaller molecular weight can be first grafted onto nanocellulose, and then other monomer A molecules or monomer A homopolymerized polymers are polymerized with the molecules or polymers that have been grafted onto nanocellulose to form a first homopolymer grafted nanocellulose. In a colloquial way, monomer A can be first "grown up", and then grafted onto nanocellulose; or monomer A or a polymer with a smaller molecular weight can be first grafted onto nanocellulose, and then "grown up" slowly. Therefore, the present application does not have a fixed or strict limitation on the ratio of nanocellulose and monomer A.

[0065] In some embodiments of the present application, in step S21, the reaction system further comprises an initiator; preferably, the initiator is selected from one or two of potassium persulfate, ammonium persulfate, sodium persulfate, sodium sulfite, potassium nitrite and cerium nitrate; preferably, the mass ratio of the initiator to monomer A is (0.2-1):1.

[0066] In some embodiments of the present application, in step S21, the extraction method of nanocellulose comprises the following steps:

[0067] S211. One or more of bagasse, cotton, cotton linters, wheat straw and mulberry bark are contacted with sulfuric acid to obtain an acidolysis system;

[0068] S212. The acidolysis system is subjected to centrifugation and dialysis treatment to obtain the nanocellulose.

[0069] In some embodiments of the present application, in step S211, the sulfuric acid is a 64wt%-66wt% sulfuric acid solution; the mass ratio of the bagasse to the sulfuric acid is (600-800):(1800-2300); the contacting condition comprises a temperature of 60°C-80°C and a time of 3-5h.

[0070] In some embodiments of the present application, in step S212, the acidolysis system is centrifuged to remove supernatant until the pH of the centrifuged system is 3.0-4.0; and then the centrifuged system is subjected to dialysis until the pH of the dialyzed system is 7.0-8.0.

[0071] According to the present application, in step S212, the centrifugation condition is not fixed or strictly limited, and can be flexibly selected by those skilled in the art according to the actual situation.

[0072] According to the present application, in step S212, the dialysis condition is not fixed or strictly limited, and can be flexibly selected by those skilled in the art according to the actual situation.

[0073] In some embodiments of the present application, the method for preparing the second homopolymer grafted nanocellulose can comprise the steps of:

[0074] (1) adding 1200-1500 g of concentrated sulfuric acid (concentration 98%) into a high-pressure reaction kettle, slowly adding deionized water, and stirring while adding (stirring speed 100 rpm) until the concentration of concentrated sulfuric acid is diluted to 65 wt%;

[0075] (2) adding 600-800 g of one or more of sugarcane residue, cotton, cotton linters, wheat straw and mulberry bark into the above reaction kettle, increasing the system temperature to 60-80℃, and increasing the stirring speed to 2000 rpm, and acidolysis reaction for 3-5 h;

[0076] (3) after the reaction is completed, the dispersion system obtained in step (2) is transferred into an ultra-high-speed centrifuge, centrifuged at 30000 rpm for 30 min, the supernatant is poured out, deionized water is added, and high-speed centrifugation is performed multiple times until the pH of the system is 3.0-4.0; then the system is transferred into a regenerated vitamin dialysis bag (20 nm) in batches, dialysis is performed for 6-9 days until the pH of the system is 7.0-8.0, the dispersion system in the dialysis bag is transferred to a rotary evaporator, and rotary evaporation is performed until the concentration of nanocellulose is 45 wt%-55 wt%, thereby obtaining a nanocellulose suspension;

[0077] (4) taking 600-800 g of the nanocellulose suspension obtained in the above step and transferring it into another high-pressure reaction kettle, adding 30-50 g of a dispersant, increasing the temperature of the reaction kettle to 40-60℃, and stirring at a speed of 300 rpm for 30-50 min;

[0078] (5) adding 15-30 g of acrylamide monomer and 7-15 g of an initiator into the above reaction kettle in sequence, reducing the temperature of the system to 20-40℃, and reducing the stirring speed to 300 rpm, and grafting reaction for 30-50 min;

[0079] (6) after the reaction is completed, the post-reaction system is filtered, and water washing, acetone washing and ether washing are performed in sequence, and finally the system is transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent, and the obtained white powder is the second homopolymer grafted nanocellulose.

[0080] According to the present application, the vitamin dialysis bag is selected from the products of Beijing Ruida Henghui Science and Technology Development Co., Ltd., and the pore size is 20 nm.

[0081] The method and conditions for filtering in step (6) are not specially limited in the present application, and a person skilled in the art can select a suitable process according to the actual situation.

[0082] The present application does not have special limitation to the method and condition of step (6) rotary evaporation, and the person skilled in the art can select appropriate process according to the actual situation.

[0083] The fourth aspect of the present application provides the application of the micro-nano fiber cleaning agent in the drilling fluid, especially as a cleaning agent, which is prepared by the micro-nano fiber cleaning agent of the second aspect or the preparation method of the third aspect.

[0084] In some embodiments of the present application, the content of the micro-nano fiber cleaning agent in the drilling fluid is 10.0wt%-15.0wt%.

[0085] According to the present application, the micro-nano fiber cleaning agent using method can include the following steps:

[0086] 1) configuring the cleaning slurry containing 10.0wt%-15.0wt% of the micro-nano fiber cleaning agent 10m 3 ;

[0087] 2) directly circulating 10m 3 cleaning slurry to the bottom of the well, standing for 20-30min, then starting the pump to restore the circulation, and the drill cuttings, blocks and the like at the bottom of the well can be directly carried out;

[0088] 3) after returning to the ground, the cleaning slurry containing drill cuttings and blocks is screened out through the vibrating screen, and after collection, the solid phase is removed through high-speed centrifugation of the centrifuge, and the remaining cleaning slurry can be reused.

[0089] According to the present application, in step 1), the drilling fluid base slurry can be prepared first, and then the cleaning slurry containing 10.0wt%-15.0wt% of the micro-nano fiber cleaning agent is prepared.

[0090] In the present application, the preparation of the drilling fluid base slurry has no fixed or strict limitation, and the person skilled in the art can flexibly prepare according to the actual situation. For example, the drilling fluid base slurry preparation method can be as follows: 4wt% of bentonite is added to 1000mL of deionized water, stirred at 10000rpm for 20min, 0.5wt% of sodium carbonate is added, and the stirring is continued at the same speed for 10min, and then it is cured for 24h.

[0091] Compared with the prior art, the present application includes at least one of the following beneficial effects:

[0092] 1) the present application designs the "rod + fluff" biomimetic micro-nano fiber cleaning agent structure with strong adsorption and cleaning effect on small solid phase particles;

[0093] 2) The invention creatively grafts the first homopolymer onto the polyester microfiber to form a "stick", crosslinks the second homopolymer grafted nanocellulose onto the "stick" to form "fluff" through the micro-crosslinking of acrylamide substances, and finally forms a biomimetic micro-nanofiber with a "stick + fluff" structure;

[0094] 3) The micro-nanofiber cleaning agent of the invention can quickly improve the structural strength of the system, has strong adsorption capacity for cuttings, and has significant cleaning effect, with a static settling factor (SF) basically varying between 0.501 and 0.511. DETAILED DESCRIPTION

[0095] The invention will be described in detail below by way of examples, but the scope of protection of the invention is not limited to the following description.

[0096] In the examples, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, but are conventional products that can be obtained by market purchase.

[0097] In the following examples, the polyester microfiber is selected from the products of Shandong Xirui Ecological Environmental Protection Technology Co., Ltd., with a diameter of 1-5 μm and a length of 500-2000 μm; the bagasse is obtained from Xilaishun Agricultural Waste Collection in Wuming County, Nanning, Guangxi, wherein the diameter of the nanocellulose is 10-20 nm and the length is 10-100 μm.

[0098] Example 1

[0099] 1. Preparation of the second homopolymer grafted nanocellulose

[0100] (1) 1200 g of concentrated sulfuric acid (concentration 98%) is added to a high-pressure reaction kettle, and deionized water is slowly added dropwise while stirring (stirring speed 100 rpm) until the concentration of the concentrated sulfuric acid is diluted to 65 wt%;

[0101] (2) 600 g of bagasse is added to the above reactor, the temperature of the system is increased to 60°C, and the stirring speed is increased to 2000 rpm, and the acidolysis reaction is carried out for 3 h;

[0102] (3) After the reaction is completed, the above dispersion system is transferred into a high-speed centrifuge, centrifuged at 30000 rpm for 30 min, and the supernatant is poured out, deionized water is added, and high-speed centrifugation is carried out for multiple times until the pH of the system is 3.0-4.0; the system is transferred into a regenerated vitamin dialysis bag (20 nm) in batches, dialysis is carried out for 6 days until the pH of the system is 7.0-8.0, the dispersion system in the dialysis bag is transferred to a rotary evaporator, and rotary evaporation is carried out until the concentration is 50%, thereby obtaining a nanocellulose suspension;

[0103] (4) Take the 600 g of nanocellulose suspension obtained in the previous step into a new high-pressure reactor, continue to add 30 g of sodium hexametaphosphate, increase the temperature of the system to 4°C, and stir at a speed of 300 rpm for 30 min;

[0104] (5) Add 15 g of acrylamide monomer and 7 g of potassium persulfate into the above reactor in sequence, reduce the temperature of the system to 20°C, reduce the stirring speed to 300 rpm, and graft for 30 min;

[0105] (6) After the reaction is completed, the system is filtered, washed with water, acetone, and diethyl ether in sequence, and finally transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent. The white powder obtained is the second homopolymer grafted nanocellulose.

[0106] 2. Preparation of first homopolymer grafted polyester microfiber

[0107] (1) Add 1200 g of polyester microfiber and 2000 g of m-cresol into a high-pressure reactor in sequence, increase the temperature of the system to 120°C, stir at a speed of 300 rpm for 30 min, and then wash with deionized water several times before being naturally dried to obtain swollen polyester microfiber;

[0108] (2) Add 800 g of swollen polyester microfiber, 1000 g of acetone, and 800 g of benzophenone into a new high-pressure reactor in sequence, increase the temperature of the system to 60°C, stir at a speed of 600 rpm for 30 min;

[0109] (3) Introduce high-purity nitrogen into the above reactor to remove oxygen for 30 min, then add 40 g of acrylamide and 20 g of potassium persulfate in sequence, and after 30 min of polymerization, add 10 g of 2-mercaptoethylamine to end the reaction;

[0110] (4) After the reaction is completed, the polyester microfiber is taken out and dispersed in deionized water again. The generated homopolymer is removed by boiling, and finally, the system is transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent. The obtained product is the first homopolymer grafted polyester microfiber.

[0111] 3. Preparation of micro-nano fiber cleaning agent

[0112] (1) Add 800 g of the first homopolymer grafted polyester microfiber, 280 g of the second homopolymer grafted nanocellulose, and 2000 g of acetone into a high-pressure reactor in sequence, increase the temperature of the reactor to 80°C, stir at a speed of 300 rpm for 30 min;

[0113] (2) Add 26 g of aluminum chloride to the above high-pressure reactor, and crosslink for 20 min;

[0114] (3) After the reaction, the system is transferred into a rotary evaporator for low-temperature rotary evaporation to remove the residual solvent, and a micro-nano fiber cleaning agent (product A1) is obtained.

[0115] The molecular weight of the obtained product A1 is 62000.

[0116] Example 2

[0117] 1. Preparation of the second homopolymer grafted nanocellulose

[0118] (1) Add 1350 g of concentrated sulfuric acid (concentration 98%) to a high-pressure reactor, slowly add deionized water, and add while stirring (stirring speed 100 rpm) until the concentration of the concentrated sulfuric acid is diluted to 65 wt%;

[0119] (2) Add 700 g of sugarcane residue to the above reactor, increase the temperature of the system to 70°C, and increase the stirring speed to 2000 rpm, and acid hydrolysis for 4 h;

[0120] (3) After the reaction, the above dispersion system is transferred into an ultrahigh-speed centrifuge and centrifuged at 30000 rpm for 30 min, and the supernatant is poured out, deionized water is added, and high-speed centrifugation is performed multiple times until the pH of the system is 3.0-4.0; the system is transferred into a regenerated vitamin dialysis bag (20 nm) in batches, dialysis is performed for 8 days until the pH of the system is 7.0-8.0, and the dispersion system in the dialysis bag is transferred to a rotary evaporator and rotary evaporated to a concentration of 50% to obtain a nanocellulose suspension;

[0121] (4) Take 700 g of the nanocellulose suspension obtained in the above step and transfer it into a new high-pressure reactor, and continue to add 40 g of sodium pyrophosphate, increase the temperature of the system to 50°C, and stir at a speed of 300 rpm for 40 min;

[0122] (5) Add 23 g of acrylamide monomer and 11 g of sodium sulfite to the above reactor in sequence, reduce the temperature of the system to 50°C, and reduce the stirring speed to 300 rpm, and graft for 40 min;

[0123] (6) After the reaction, the system is filtered, washed with water, acetone, and ether in sequence, and finally transferred into a rotary evaporator for low-temperature rotary evaporation to remove the residual solvent, and the obtained white powder is the second homopolymer grafted nanocellulose.

[0124] 2. Preparation of the first homopolymer grafted polyester microfiber

[0125] (1) In a high-pressure reactor, 1350 g of polyester micron fiber and 2250 g of m-cresol were sequentially added, the temperature of the system was raised to 135°C, the stirring speed was 300 rpm, and the swelling reaction was carried out for 40 min. After the reaction, the system was washed with deionized water several times, and then naturally dried to obtain the swollen polyester micron fiber;

[0126] (2) In a new high-pressure reactor, 1000 g of the swollen polyester micron fiber, 1100 g of acetone, and 900 g of benzophenone were sequentially added, the temperature of the system was raised to 70°C, the stirring speed was 600 rpm, and the dispersion was carried out for 40 min;

[0127] (3) In the above reactor, high-purity nitrogen was introduced to remove oxygen for 30 min, then 60 g of acrylamide and 30 g of sodium sulfite were sequentially added, the polymerization reaction was carried out for 40 min, then 13 g of β-mercaptoethanol was added, and the reaction was completed;

[0128] (4) After the reaction was completed, the polyester micron fiber was taken out and dispersed in deionized water, the generated homopolymer was removed by boiling, and finally, the remaining solvent was removed by low-temperature rotary evaporation in a rotary evaporator. The obtained product is the first homopolymer grafted polyester micron fiber.

[0129] 3. Preparation of a biomimetic micro-nano fiber cleaning agent for drilling fluid

[0130] (1) In a high-pressure reactor, 1000 g of the first homopolymer grafted polyester micron fiber, 330 g of the second homopolymer grafted nano-cellulose, and 2250 g of acetone were sequentially added, the temperature of the reactor was raised to 90°C, the stirring speed was 300 rpm, and the dispersion was carried out for 40 min;

[0131] (2) In the above high-pressure reactor, 29 g of zirconium chloride was added, and the micro-crosslinking reaction was carried out for 30 min;

[0132] (3) After the reaction was completed, the post-reaction system was transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent, and the micro-nano fiber cleaning agent (product A2) was obtained.

[0133] The molecular weight of the obtained product A2 is 72500.

[0134] Example 3

[0135] 1. Preparation of second homopolymer grafted nano-cellulose

[0136] (1) In a high-pressure reactor, 1500 g of concentrated sulfuric acid (concentration 98%) was added, and deionized water was slowly added while stirring (stirring speed 100 rpm) until the concentration of the concentrated sulfuric acid was diluted to 65 wt%;

[0137] (2) In the above reactor, 800 g of bagasse was added, the temperature of the system was increased to 80°C, the stirring speed was increased to 2000 rpm, and the acidolysis reaction was carried out for 5 h;

[0138] (3) After the reaction was completed, the above dispersion system was transferred into an ultrahigh-speed centrifuge, centrifuged at 30000 rpm for 30 min, and the supernatant was poured out. Ion-free water was added, and high-speed centrifugation was carried out for multiple times until the pH of the system was 3.0-4.0. The system was transferred into a regenerated vitamin dialysis bag (20 nm) in batches, dialyzed for 9 days until the pH of the system was 7.0-8.0, and the dispersion system in the dialysis bag was transferred to a rotary evaporator and rotary evaporated until the concentration was 50% to obtain a nanocellulose suspension;

[0139] (4) 800 g of the nanocellulose suspension obtained in the above step was transferred into a new high-pressure reaction kettle, and 50 g of sodium tannate was continuously added. The temperature of the system was increased to 60°C, the stirring speed was 300 rpm, and the dispersion was carried out for 0 min;

[0140] (5) 30 g of acrylamide monomer and 15 g of cerium nitrate were sequentially added to the above reactor, the temperature of the system was reduced to 60°C, the stirring speed was reduced to 300 rpm, and the grafting reaction was carried out for 50 min;

[0141] (6) After the reaction was completed, the system was filtered, sequentially washed with water, acetone and diethyl ether, and finally transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent. The obtained white powder was the second homopolymer grafted nanocellulose.

[0142] 2. Preparation of first homopolymer grafted polyester micron fiber

[0143] (1) In a high-pressure reaction kettle, 1500 g of polyester micron fiber and 2500 g of m-cresol were sequentially added, the temperature of the system was increased to 150°C, the stirring speed was 300 rpm, the swelling reaction was carried out for 50 min, and after the reaction, the system was washed with deionized water several times and then naturally dried to obtain swollen polyester micron fiber;

[0144] (2) In a new high-pressure reaction kettle, 1200 g of swollen polyester micron fiber, 1200 g of acetone and 1000 g of benzophenone were sequentially added, the temperature of the system was increased to 80°C, the stirring speed was 600 rpm, and the dispersion was carried out for 50 min;

[0145] (3) High-purity nitrogen was introduced into the above reactor to remove oxygen for 30 min, and then 80 g of acrylamide and 40 g of cerium nitrate were sequentially added. After the polymerization reaction was carried out for 50 min, 16 g of dodecyl mercaptan was added to end the reaction;

[0146] (4) After the reaction is completed, the polyester microfiber is taken out and re-dispersed in deionized water, the generated homopolymer is removed by boiling, and finally, the remaining solvent is removed by low-temperature rotary evaporation in a rotary evaporator. The obtained product is the first homopolymer grafted polyester microfiber.

[0147] 3. Preparation of a biomimetic micro-nano fiber cleaning agent for drilling fluid

[0148] (1) In a high-pressure reaction kettle, 1200 g of the first homopolymer grafted polyester microfiber, 380 g of the second homopolymer grafted nanocellulose, and 2500 g of acetone are sequentially added, the temperature of the reaction kettle is raised to 100°C, the stirring speed is 300 rpm, and the dispersion is performed for 50 min.

[0149] (2) In the above high-pressure reaction kettle, 32 g of iron bromide is added, and the micro-crosslinking reaction is performed for 40 min.

[0150] (3) After the reaction is completed, the reaction system is transferred into a rotary evaporator for low-temperature rotary evaporation to remove the remaining solvent, and the micro-nano fiber cleaning agent (product A3) is obtained.

[0151] The molecular weight of the obtained product A3 is 85000.

[0152] Example 4

[0153] 1. Preparation of second homopolymer grafted nanocellulose

[0154] The same as example 1, except that methacrylamide is used instead of acrylamide in example 1.

[0155] 2. Preparation of first homopolymer grafted polyester microfiber

[0156] The same as example 1, except that methacrylamide is used instead of acrylamide in example 1.

[0157] 3. Preparation of micro-nano fiber cleaning agent

[0158] The same as the preparation method of example 1, the micro-nano fiber cleaning agent (product A4) is prepared.

[0159] The molecular weight of the obtained product A4 is 76000.

[0160] Example 5

[0161] 1. Preparation of second homopolymer grafted nanocellulose

[0162] The same as example 1, except that cotton is used instead of sugarcane residue in example 1.

[0163] 2. Preparation of first homopolymer grafted polyester microfiber

[0164] The preparation method is the same as that of Example 1.

[0165] 3. Preparation of micro-nano fiber cleaning agent

[0166] The micro-nano fiber cleaning agent (product A5) is prepared in the same way as the preparation method of Example 1.

[0167] The molecular weight of the obtained product A5 is 64500.

[0168] Test example

[0169] Experimental slurry preparation: 4wt% bentonite was added to 1000mL deionized water, stirred at 10000rpm for 20min, then 0.5wt% sodium carbonate was added, and the same speed was continued to stir for 10min, and then cured for 24h.

[0170] The static settling stability method was used to determine the cleaning ability of the micro-nano fiber cleaning agent prepared drilling fluid to drill cuttings. 10.0wt% micro-nano fiber cleaning agent sample was added to the experimental slurry (drill cuttings addition amount was 10.0wt%, and the prepared drilling fluid density was 1.50-1.59g / cm 3 ), and then the drilling fluid was added to a stainless steel tank, and was placed at room temperature and 150℃ for 36h. After taking out, the top density ρtop and bottom density ρbottom of the drilling fluid were determined respectively. The static settling factor was calculated as follows:

[0171] SF=ρ bottom / (ρ bottom +ρ top )(1)

[0172] When SF is equal to 0.50, it means that no static settling occurs; when SF is greater than 0.65, it means that obvious settling occurs, indicating that the settling stability of the drilling fluid is poor.

[0173] The static settling factors of products A1-A4 and the comparative sample polyacrylamide (molecular weight 1.0×10 6 -2.0×10 6 ) were tested, and the static settling factors under two conditions of room temperature and 150℃ / 3.5MPa were tested, and the results are shown in the following table:

[0174]

[0175] From Table 1, it can be seen that the drilling fluid prepared by the product A1-A5 of each embodiment of the present application has obvious effect, strong suspension capacity and high settlement stability under normal temperature condition and high temperature and high pressure condition; when the addition amount is 10.0wt%, the static settlement factor is stable at 0.501-0.511, and under the condition of 150℃, the static settlement factor changes little; while the settlement stability of polyacrylamide is higher under normal temperature, but decreases rapidly after high temperature. Therefore, the carrying and cleaning capacity of the drilling fluid prepared by the micro-nano fiber cleaning agent of the present application is excellent under high temperature.

[0176] It should be noted that the above-described embodiments are only used for explaining the present application and do not constitute any limitation to the present application. The present application is described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications having the same function.

Claims

1. A method for preparing a micro-nanofiber cleaning agent, characterized by, The method comprises the steps of: S1. reacting a raw material system comprising a composition and a solvent to obtain a reaction product containing micro-nano fiber scavenger; and Optionally, S2. removing the solvent contained in the reaction product to obtain the micro-nano fiber scavenger, The composition comprises the following components in parts by weight: First homopolymer grafted polyester micro fiber 70-76 parts; Second homopolymer grafted nanocellulose 22-28 parts; Crosslinking agent 1-3 parts; The first homopolymer and the second homopolymer are the same or different, and each is independently derived from monomer A; The diameter of the polyester micro fiber is 1-5 μm, and the length is 500-2000 μm; The diameter of the nanocellulose is 10-20 nm, and the length is 10-100 μm; The monomer A is selected from monomers having a structure shown in formula (I); Formula (I) In formula (I), R1 is selected from hydrogen, C1-C5 linear alkyl, C3-C5 branched alkyl and C3-C5 cyclic alkyl.

2. The production method according to claim 1, characterized by, The composition comprises the following components in parts by weight: First homopolymer grafted polyester micro fiber 72-74.5 parts; Second homopolymer grafted nanocellulose 23.5-25.5 parts; Crosslinking agent 1.5-2.5 parts.

3. The production method according to claim 1 or 2, characterized by, The weight average molecular weight of the first homopolymer is 200-500.

4. The production method according to claim 1 or 2, characterized by, The weight average molecular weight of the second homopolymer is 100-200.

5. The production method according to claim 1 or 2, characterized by, In formula (I), R1 is selected from hydrogen or C1-C5 linear alkyl.

6. The production method according to claim 1 or 2, characterized by, In formula (I), R1 is selected from hydrogen, methyl or ethyl.

7. The production method according to claim 1 or 2, characterized by, The grafting rate of the first homopolymer in the first homopolymer grafted polyester micro fiber is 30%-50%; and / or the grafting rate of the second homopolymer in the second homopolymer grafted nanocellulose is 40%-60%.

8. The production method according to claim 1 or 2, characterized by, The polyester micro fiber is a polydiacid diol ester micro fiber; and / or The nanocellulose is extracted from one or more of sugarcane residue, cotton, cotton linter, wheat straw and mulberry bark; and / or The crosslinking agent is selected from one or more of aluminum chloride, aluminum bromide, zirconium chloride, zirconium bromide, iron chloride and iron bromide.

9. The preparation method according to claim 8, characterized in that The polydiacid diol ester is polyethylene terephthalate; and / or The crosslinking agent is selected from one or more of aluminum chloride, aluminum bromide, iron chloride and iron bromide.

10. The method of claim 9, wherein, The polyhydric acid glycol ester general formula is HO-H2C-H2C-O[-OC-Ph-COOCH2CH2O-] n H, the number average molecular weight is 22000~25000; and / or The crosslinking agent is selected from aluminum chloride and / or iron chloride.

11. The production method according to claim 1 or 2, characterized by, In step S1, the solvent is selected from one or more of acetone, isopropyl alcohol and propanol; and / or In step S1, the reaction conditions include a temperature of 80-100°C and a time of 20-40 min.

12. The method of claim 11, wherein, In step S1, the solvent is acetone.

13. The production method according to claim 1 or 2, characterized by, The preparation method of the first homopolymer grafted polyester micro fiber comprises the steps of: S11. swelling a reaction system comprising polyester micro fiber and a solvent to obtain swollen polyester micro fiber; S12. contacting the swollen polyester micro fiber, acetone and benzophenone to obtain a post-dispersion system; S13. grafting a raw material system comprising the post-dispersion system and monomer A to obtain a reaction product I containing first homopolymer grafted polyester micro fiber; and and Optionally, S14. After the treatment of heating and removing the residual solvent of the reactant I, the first homopolymer grafted polyester micro fiber is obtained.

14. The method of claim 13, wherein, In step S11, the solvent is m-cresol; the mass ratio of the polyester micro fiber to the solvent is (12~15):(20~25); the mixing conditions of the polyester micro fiber and the solvent include: the temperature is 120℃~150℃, the stirring speed is 250~350rpm, and the time is 30~50min; and / or In step S12, the mass ratio of the swelled polyester micro fiber, acetone and benzophenone is (8~12):(10~12):(8~10); the dispersion conditions include: the temperature is 60℃~80℃, the stirring speed is 550~650rpm, and the time is 30~50min; and / or In step S13, the raw material system further comprises an initiator and a chain transfer agent.

15. The preparation method according to claim 14, characterized in that The initiator is selected from one or two of potassium persulfate, ammonium persulfate, sodium persulfate, sodium sulfite, potassium nitrite and cerium nitrate; and / or the chain transfer agent is selected from one or two of 2-mercaptoethylamine, β-mercaptoethanol and dodecyl mercaptan.

16. The method of claim 15, wherein, The mass ratio of the initiator to monomer A is (0.25~1):1, and the mass ratio of the chain transfer agent to monomer A is (0.125~0.4):

1.

17. The method of making according to claim 1 or 2, wherein, The preparation method of the second homopolymer grafted nanocellulose comprises steps of: S21. The raw material system comprising the nanocellulose and monomer A is subjected to a grafting reaction to obtain a reactant I containing the second homopolymer grafted nanocellulose; and Optionally, S22. After the filtration, washing and removal of the solvent of the reactant I, the second homopolymer grafted nanocellulose is obtained.

18. The method of claim 17, wherein, In step S21, the raw material system further comprises an initiator.

19. The method of claim 18, wherein, The initiator is selected from one or two of potassium persulfate, ammonium persulfate, sodium persulfate, sodium sulfite, potassium nitrite and cerium nitrate.

20. The method of claim 19, wherein, The mass ratio of the initiator to monomer A is (0.2~1):

1.

21. The method of claim 17, wherein, In step S21, the extraction method of the nanocellulose comprises steps of: S211. One or more of sugarcane residue, cotton, cotton linters, wheat straw and mulberry bark is contacted with sulfuric acid to obtain an acidolysis system; S212. The acidolysis system is subjected to centrifugation and dialysis treatment to obtain the nanocellulose.

22. The method of claim 21, wherein, In step S211, the sulfuric acid is a 64wt%~66wt% sulfuric acid solution; the mass ratio of the sugarcane residue to the sulfuric acid is (600~800):(1800~2300); and the contacting conditions include: the temperature is 60℃~80℃, and the time is 3~5h; and / or In step S212, the supernatant is removed from the acidolysis system by centrifugation until the pH of the centrifuged system is 3.0~4.0; and the centrifuged system is subjected to dialysis until the pH of the dialyzed system is 7.0~8.

0.

23. A micro-nano fiber cleaning agent prepared by the preparation method according to any one of claims 1~22.

24. The micro- and nano-fiber cleaning agent of claim 23, wherein, The weight average molecular weight of the micro-nano fiber cleaning agent is 60000~90000.

25. The use of the micro-nano fiber cleaning agent prepared by the method according to any one of claims 1-22 or the micro-nano fiber cleaning agent according to claim 23 or 24 in a drilling fluid.

26. The use according to claim 25, characterized in that, As a cleaning agent.

27. Use according to claim 25 or 26, characterised in that, The content of the micro-nano fiber cleaning agent in the drilling fluid is 10.0wt%-15.0wt%.

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