Modified polymer plugging anti-collapse agent for drilling fluid and preparation method of modified polymer plugging anti-collapse agent

Abstract

The invention provides a modified polymer plugging anti-collapse agent for drilling fluid. The modified polymer plugging anti-collapse agent is obtained by chloromethylation and amination modification of a lipophilic polymer. Compared with the prior art, the plugging leakage-proof agent provided by the invention has the advantages that the main body is the oleophylic polymer, and the plugging leakage-proof agent has good lipophilicity and good chemical stability, can resist the temperature of 180 DEG C, and is suitable for plugging, leakage prevention and collapse prevention of high-temperature drilling fluid; after the surface of the oleophylic polymer is subjected to amination modification, the oleophylic polymer has good hydrophilicity, can inhibit hydration expansion of clay and has an anti-collapse effect; the water-based drilling fluid plugging agent is easy to disperse in oil-based drilling fluid and water-based drilling fluid, is easy to crush, has wide particle size distribution, can be screened as required, has toughness deformation at high temperature, and has good plugging, leakage-proof and collapse-proof properties in the oil-based drilling fluid and the water-based drilling fluid; furthermore, the main raw material oleophylic polymer of the plugging anti-collapse agent can adopt industrial waste, is low in price and rich in source, and is convenient for large-scale production and application.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a modified polymer plugging and anti-collapse agent for drilling fluid and a preparation method thereof. Background Art

[0002] In the exploration and development of deep and ultra-deep wells, drilling fluids usually face the following challenges: it is difficult to maintain the performance of drilling fluids under high temperatures; the open hole section is long, prone to well collapse and obstruction; the problem of well leakage is serious, and the loss of leakage control is large; the drilled strata have high and steep structures, many faults, developed fractures and pores, and many leaky layers, resulting in the coexistence of multiple complex situations.

[0003] The Hongxing Block is the main gas-producing area of ​​the Jianghan Oilfield, which is located in the Jiannan structure of the Shizhu complex syncline in the high and steep fault fold belt in the eastern Sichuan Basin. The drilling in this block is very different. The cracks and microcracks are well developed in the southern area, and the well leakage is higher than that in the northern area. The Hongye 5HF well has lost 27 times in the direct pilot hole, and 9 special plugging operations have been carried out, with 2050.42m3 of mud lost, affecting the drilling cycle by 157.5h. The instability of the well wall in the northern area is prominent, and there is a problem of collapse and leakage. In addition, there are fewer types of plugging and anti-collapse agents for oil-based drilling fluids, and even fewer amphiphilic plugging materials, which cannot effectively meet the needs of the site. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a modified polymer plugging and anti-collapse agent for drilling fluid and a preparation method thereof. The modified polymer for drilling fluid provided by the present invention has excellent temperature resistance and can overcome the plugging problem of high-temperature deep well oil-based drilling fluid and water-based drilling fluid above 180°C.

[0005] The invention provides a modified polymer plugging and anti-collapse agent for drilling fluid, which is obtained by modifying an oleophilic polymer through chloromethylation and amination.

[0006] Preferably, the lipophilic polymer is selected from one or more of polystyrene, cross-linked polystyrene, polyacrylonitrile-styrene, cross-linked polyacrylonitrile-styrene, polystyrene-methyl methacrylate, cross-linked polystyrene-methyl methacrylate, polyacrylonitrile-butadiene-styrene and cross-linked polyacrylonitrile-butadiene-styrene.

[0007] Preferably, the lipophilic polymer is industrial waste.

[0008] The present invention also provides a method for preparing a modified polymer plugging and anti-collapse agent for drilling fluid, comprising the following steps:

[0009] S1) chloromethylating the oleophilic polymer to obtain a chloromethylated polymer;

[0010] S2) aminate-modifying the chloromethylated polymer to obtain a modified polymer plugging and leak-proofing agent for drilling fluid.

[0011] Preferably, the step S1) is specifically:

[0012] In the presence of a catalyst, the oleophilic polymer and the chloromethylation agent are mixed and reacted in a first organic solvent to obtain a chloromethylated polymer.

[0013] Preferably, the catalyst is selected from one or more of P2O5, ZnCl2, SnCl4 and TiCl4;

[0014] The chloromethylation agent is selected from 1,4-dichloromethoxybutane;

[0015] The first organic solvent is selected from one or more of dichloromethane, chloroform and carbon tetrachloride.

[0016] Preferably, the mass of the catalyst is 0.5 to 4 times the mass of the oleophilic polymer;

[0017] The mass of the chloromethylation reagent is 2 to 20 times the mass of the lipophilic polymer;

[0018] The mass of the first organic solvent is 20 to 50 times the mass of the lipophilic polymer.

[0019] Preferably, the amination reagent used for the amination modification in step S2) is selected from one or more of trimethylamine, triethylamine and pyridine; the mass of the amination reagent is 2 to 6 times the mass of the chloromethylated polymer;

[0020] The amination modification is carried out in a second organic solvent; the second organic solvent is selected from one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide and toluene; the mass of the second organic solvent is 2 to 10 times the mass of the chloromethylated polymer.

[0021] Preferably, after the amination modification in step S2), granulation is further performed to obtain a modified polymer plugging and leak-proofing agent for drilling fluid; the modified polymer plugging and leak-proofing agent for drilling fluid has a D 50 The particle size is 20~100μm.

[0022] The invention provides a drilling fluid, comprising the modified polymer plugging and anti-collapse agent for drilling fluid.

[0023] The present invention provides a modified polymer plugging and anti-collapse agent for drilling fluid, which is obtained by modifying an oleophilic polymer through chloromethylation and amination. Compared with the prior art, the plugging and anti-leakage agent provided by the present invention is mainly an oleophilic polymer, has good oleophilicity, good chemical stability, and temperature resistance of up to 180°C, and is suitable for plugging, preventing leakage and preventing collapse of high-temperature drilling fluid; after the surface of the oleophilic polymer is modified through amination, it has good hydrophilicity, can inhibit clay hydration and expansion, and has an anti-collapse effect; it is not only easy to disperse in oil-based drilling fluid and water-based drilling fluid, but also easy to crush, with a wide particle size distribution, can be screened according to needs, has toughness deformation at high temperature, and has good plugging, anti-leakage and anti-collapse properties in both oil-based drilling fluid and water-based drilling fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A diagram showing the reaction process for preparing the modified polymer plugging and anti-collapse agent for drilling fluid provided by the present invention;

[0025] Figure 2 The general product structure diagram of the modified polymer plugging and anti-collapse agent for drilling fluid provided by the present invention;

[0026] Figure 3 This is the infrared spectrum of Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The invention provides a modified polymer plugging and anti-collapse agent for drilling fluid, which is obtained by modifying an oleophilic polymer through chloromethylation and amination.

[0029] The lipophilic polymer may be any lipophilic polymer known to those skilled in the art without any particular limitation. In the present invention, it is preferably a styrene homopolymer and / or a styrene copolymer, and more preferably includes but is not limited to one or more of polystyrene, cross-linked polystyrene, polyacrylonitrile-styrene, cross-linked polyacrylonitrile-styrene, polystyrene-methyl methacrylate, cross-linked polystyrene-methyl methacrylate, polyacrylonitrile-butadiene-styrene and cross-linked polyacrylonitrile-butadiene-styrene; the weight average molecular weight of the lipophilic polymer is preferably 5000-150000, more preferably 5000-120000, and even more preferably 5000-100000.

[0030] The present invention has no particular limitation on the source of the lipophilic polymer, which may be unused or used waste. In the present invention, industrial waste is preferred, which is cheap, abundant in source, and easy to promote and apply.

[0031] The modified polymer plugging and anti-collapse agent for drilling fluid is preferably used in high-temperature formations above 180°C.

[0032] The plugging and leak-proofing agent provided by the present invention is mainly composed of an oleophilic polymer, which has good oleophilicity, good chemical stability, and temperature resistance of up to 180°C, and is suitable for plugging, leak-proofing and collapse-proofing of high-temperature drilling fluids; after the surface of the oleophilic polymer is modified by amination, it has good hydrophilicity, can inhibit clay hydration expansion, and has an anti-collapse effect; it is not only easy to disperse in oil-based drilling fluids and water-based drilling fluids, but also easy to crush, with a wide particle size distribution, can be screened according to needs, has toughness deformation at high temperatures, and has good plugging, leak-proofing and collapse-proofing properties in both oil-based drilling fluids and water-based drilling fluids.

[0033] The present invention also provides a method for preparing the modified polymer plugging and anti-collapse agent for drilling fluid, comprising the following steps: S1) chloromethylating the oleophilic polymer to obtain a chloromethylated polymer; S2) aminating the chloromethylated polymer to obtain the modified polymer plugging and anti-leakage agent for drilling fluid.

[0034] See also Figure 1 , Figure 1 This is a reaction process diagram for preparing the modified polymer plugging and anti-collapse agent for drilling fluid provided by the present invention.

[0035] See also Figure 2 , Figure 2 This is a general product structure diagram of the modified polymer plugging and anti-collapse agent for drilling fluid provided by the present invention.

[0036] The present invention has no particular limitation on the sources of all raw materials, and any raw materials available on the market can be used.

[0037] The oleophilic polymer is modified by chloromethylation; the oleophilic polymer is the same as described above and will not be described in detail here; when the oleophilic polymer is an industrial waste material, it is preferably first surface cleaned and then chloromethylated; the step of chloromethylating the oleophilic polymer is preferably specifically: in the presence of a catalyst, the oleophilic polymer and a chloromethylation agent are mixed and reacted in a first organic solvent; the catalyst can be a catalyst used for chloromethylation well known to those skilled in the art, and there is no special limitation. The present invention preferably includes but is not limited to one or more of P2O5, ZnCl2, SnCl4 and TiCl4; the mass of the catalyst is preferably 0.5 to 4 times the mass of the oleophilic polymer, more preferably 0.8 to 3 times, and more preferably 1 to 2.5 times; in some embodiments provided by the present invention, the mass of the catalyst is specifically 1.115 times or 2.23 times the mass of the oleophilic polymer; the chloromethylation agent can be a chloromethylation agent well known to those skilled in the art, and there is no special limitation. The mass of the chloromethylation agent is preferably 2 to 20 times, more preferably 4 to 15 times, and more preferably 5 to 10 times the mass of the lipophilic polymer; in the embodiment provided by the present invention, the mass of the chloromethylation agent is specifically 5.7 times or 9.2 times the mass of the lipophilic polymer; the first organic solvent is an organic solvent well known to those skilled in the art, and there is no special limitation. The present invention preferably includes but is not limited to one or more of dichloromethane, chloroform and carbon tetrachloride; the mass of the first organic solvent is preferably 20 to 50 times, more preferably 30 to 45 times, and more preferably 35 to 40 times the mass of the lipophilic polymer; in the present invention, it is preferred that the lipophilic polymer and the first organic solvent are mixed, swollen or dissolved, a catalyst is added, and then the chloromethylation agent is added dropwise to react; the reaction time is preferably 10 to 30 hours, more preferably 15 to 25 hours, and more preferably 20 hours; the reaction is carried out under stirring.

[0038] The chloromethylated polymer is subjected to amination modification; the amination agent used for the amination modification is preferably one or more of trimethylamine, triethylamine and pyridine; the mass of the amination agent is preferably 2 to 10 times the mass of the chloromethylated polymer, more preferably 2 to 8 times, more preferably 2 to 6 times, more preferably 2 to 5 times, most preferably 2 to 3 times; the amination modification is carried out in a second organic solvent; the second organic solvent is preferably one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide and toluene; the mass of the second organic solvent is preferably 2 to 10 times, more preferably 4 to 10 times, more preferably 6 to 10 times, and most preferably 7.5 to 10 times; in some embodiments provided by the present invention, the mass of the second organic solvent is specifically 9.84 times or 7.87 times the mass of the chloromethylated polymer; in the present invention, it is preferred that the chloromethylated polymer is first swollen or dissolved in the second organic solvent, and then an amination reagent is added for amination modification; the temperature of the amination modification is preferably 40°C to 60°C, more preferably 45°C to 50°C; the time of the amination modification is preferably 5 to 15h, more preferably 8 to 12h, and more preferably 10h.

[0039] After the amination modification, it is preferably further crushed and sieved to obtain a modified polymer plugging and leak-proofing agent for drilling fluid; it is preferably washed and dried before crushing; the D50 particle size of the modified polymer plugging and leak-proofing agent for drilling fluid is preferably 20 to 100 μm, and it can be sieved according to needs, and has a wide range of applications.

[0040] The modified polymer plugging and anti-collapse agent prepared by the invention has good hydrophilicity and lipophilicity, and has good compatibility with water-based drilling fluid and oil-based drilling fluid; it is easy to crush, can be screened according to needs, and is suitable for drilling-while-drilling applications; it has strong temperature resistance, and still has good plugging performance when the temperature of the formation encountered during drilling is higher than 180°C; it can effectively inhibit the hydration of bentonite and improve the stability of the well wall; and the plugging and anti-collapse agent uses lipophilic polymer industrial waste as raw material, is cheap, has abundant sources, and is easy to promote and apply.

[0041] The present invention also provides a drilling fluid, comprising the modified polymer plugging and anti-collapse agent for drilling fluid.

[0042] The drilling fluid may be an oil-based drilling fluid or a water-based drilling fluid.

[0043] The drilling fluid is preferably used in high-temperature formations above 180°C.

[0044] The mass concentration of the modified polymer plugging and anti-collapse agent for drilling fluid in the drilling fluid is preferably 0.5% to 4%.

[0045] The modified polymer plugging and anti-collapse agent for drilling fluid in the drilling fluid 50The particle size distribution is 20-100μm, and it can be screened as needed, which can participate in the formation of mud cake, improve the quality of mud cake, and have a good while-drilling plugging effect.

[0046] According to the present invention, the liquid phase of the oil-based drilling fluid preferably includes an oil phase and an aqueous phase; the volume ratio of the oil phase to the aqueous phase is preferably (7-9):(1-3), more preferably (8-8.5):(2-1.5); the oil phase is preferably diesel and / or white oil; the aqueous phase is preferably a calcium chloride aqueous solution and / or a potassium sulfate aqueous solution; the mass concentration of the calcium chloride aqueous solution and / or the potassium sulfate aqueous solution is preferably 15%-35%, more preferably 20%-25%.

[0047] According to the present invention, the oil-based drilling fluid preferably also includes an emulsifier; the mass of the emulsifier is preferably 1% to 10% of the mass of the oil-based drilling fluid, more preferably 3% to 6%, and even more preferably 4% to 6%; the emulsifier can be an emulsifier well known to those skilled in the art, and there is no special limitation; in the embodiments provided by the present invention, polyamide emulsifiers are specifically taken as an example for description.

[0048] According to the present invention, the oil-based drilling fluid preferably further comprises calcium oxide; the mass of the calcium oxide is preferably 1% to 5% of the mass of the oil-based drilling fluid, more preferably 2% to 4%.

[0049] According to the present invention, the oil-based drilling fluid preferably further comprises organic soil; the mass of the organic soil is preferably 1% to 5% of the mass of the oil-based drilling fluid, more preferably 2% to 3%.

[0050] According to the present invention, the oil-based drilling fluid preferably also includes a fluid loss reducer; the mass of the fluid loss reducer is preferably 1% to 5% of the mass of the oil-based drilling fluid, and more preferably 2% to 4%; the type of the fluid loss reducer can be any fluid loss reducer well known to those skilled in the art, and there is no special limitation. In the present invention, an asphalt resin fluid loss reducer is preferred, and an oxidized asphalt fluid loss reducer is more preferred.

[0051] According to the present invention, the water-based drilling fluid can be any water-based drilling fluid well known to those skilled in the art without any special limitation. The water-based drilling fluid in the present invention preferably includes water and bentonite; the mass of the bentonite is preferably 5% to 10% of the mass of the water-based drilling fluid, and more preferably 7% to 8%.

[0052] In order to further illustrate the present invention, the following describes in detail a modified polymer plugging and anti-collapse agent for drilling fluid and a preparation method thereof in conjunction with embodiments.

[0053] The reagents used in the following examples are all commercially available; the cross-linked polystyrene microspheres and polystyrene-methyl methacrylate used in the examples are crushed with a small swing mill and passed through a 140-200 mesh sieve.

[0054] Example 1

[0055] The preparation method of the modified polymer plugging and anti-collapse agent of the present invention comprises the following steps:

[0056] In a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer, 10g of cross-linked polystyrene (Jiangsu Andeli New Material Technology Co., Ltd., solid lubricant for drilling fluid (plastic balls), cross-linking degree 5% to 7%) was added to a container containing 250ml of CCl4, fully swollen, 5mL of SnCl4 was added, and 50mL of 1,4-dichloromethoxybutane was slowly added dropwise. The mixture was stirred at room temperature and reacted for 20h. After the reaction was completed, it was filtered, washed and dried to obtain a chloromethylated polymer;

[0057] 5 g of chloromethylated polymer was added to a three-necked flask, swollen with 40 mL of N, N-dimethylformamide, and then 20 mL of trimethylamine was added. The temperature was raised to 45°C and stirred for reaction for 10 h. After the reaction was completed, the mixture was filtered, washed and dried, and then crushed with a small swing mill and passed through a 140-200 mesh sieve to obtain the modified polymer plugging and anti-collapse agent. The infrared spectrum is shown as follows: Figure 3 shown.

[0058] Example 2

[0059] The preparation method of the modified polymer plugging and anti-collapse agent of the present invention comprises the following steps:

[0060] In a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer, 10g of polystyrene-methyl methacrylate (Hubei Wonder Chemical Co., Ltd.) was added to a container containing 250mL of CCl4, fully swollen, 10mL of SnCl4 was added, 80mL of 1,4-dichloromethoxybutane was slowly added dropwise, and the mixture was stirred at room temperature for 20h. After the reaction was completed, the mixture was filtered, washed and dried to obtain a chloromethylated polymer;

[0061] 5 g of chloromethylated polymer was added to a three-necked flask, swollen with 50 mL of N, N-dimethylformamide, and then 15 mL of trimethylamine was added. The temperature was raised to 45° C. and stirred for reaction for 10 hours. After the reaction was completed, the mixture was filtered, washed, dried, crushed with a small swing mill, and passed through a 140-200 mesh sieve to obtain the modified polymer plugging and anti-collapse agent.

[0062] Comparative Example 1

[0063] The cross-linked polystyrene (Jiangsu Andeli New Material Technology Co., Ltd., solid lubricant for drilling fluid (plastic pellets), cross-linking degree 5% to 7%) was washed, dried, crushed with a small swing crusher, and passed through a 140-200 mesh sieve to obtain Comparative Example 1.

[0064] Comparative Example 2

[0065] Commonly used polystyrene-methyl methacrylate (Hubei Wonder Chemical Co., Ltd.) was cleaned, dried, crushed with a small swing mill, and passed through a 140-200 mesh sieve to obtain Comparative Example 2.

[0066] The products prepared in the examples of the present invention were evaluated, and the results were as follows:

[0067] (1) Particle size analysis

[0068] The modified polymer plugging and anti-collapse agent obtained in the embodiment was measured by a laser particle size analyzer, and the results are shown in Table 1. As can be seen from Table 1, the particle size of the modified polymer plugging and anti-collapse agent for drilling fluid obtained in the present invention is micron-level, can be applied to plugging while drilling, and is suitable for plugging microcracks and pores.

[0069] Table 1 Particle size D of the product of the embodiment 50

[0070] Serial number <![CDATA[Particle size D 50 , μm]]> Example 1 22.36 Example 2 28.45 Comparative Example 1 42.67 Comparative Example 2 39.43

[0071] (2) Plugging evaluation

[0072] ①Oil-based drilling fluid

[0073] The modified polymer plugging and anti-collapse agent for drilling fluid obtained by the reaction of the embodiment was added to the oil-based drilling fluid, and after high-temperature aging at 180°C for 16 hours, the rheological properties of the drilling fluid were measured using a six-speed rotary viscometer at 65°C, and the high-temperature and high-pressure filtration loss of the drilling fluid and the sealing filtration loss of 380-830 μm river sand (normal temperature, 0.69 MPa) were measured. The results are shown in Table 2. As can be seen from Table 2, when the product of the present invention is added to the oil-based drilling fluid, the rheological properties of the drilling fluid system do not change much; the high-temperature and high-pressure filtration loss is reduced. This shows that the modified polymer plugging and anti-collapse agent has good compatibility with the oil-based drilling fluid and has good filtration loss reduction and plugging performance.

[0074] Table 2 Evaluation of product dosage and drilling fluid compatibility in the examples

[0075]

[0076]

[0077] Note: The base slurry composition is (0 # Diesel oil: 20% calcium chloride aqueous solution = 80:20) + 4% oil-based drilling fluid emulsifier LEMUL + 2% calcium oxide + 2% organic soil + 2% asphalt resin fluid loss reducer OFC-1 (density 2.2g / cm 3); emulsifier, Zhongyuan Petroleum Engineering Co., Ltd. (patent No. ZL.201711027059.X, Example 6); organic soil, Zhejiang Fenghong New Materials Co., Ltd. (BS-1C); fluid loss reducer is an oxidized asphalt fluid loss reducer, Shandong Deshunyuan Petroleum Technology Co., Ltd. (OFC).

[0078] ② Water-based drilling fluid

[0079] The modified polymer plugging and anti-collapse agent for drilling fluid obtained by the reaction of the embodiment was added to the water-based drilling fluid, and the apparent viscosity was measured by a six-speed rotary viscometer at room temperature. The results are shown in Table 3. As can be seen from Table 3, the product of the present invention can effectively inhibit the hydration expansion and dispersion of clay in the water-based drilling fluid, and has a good anti-collapse effect.

[0080] Table 3 Example product dosage and clay inhibition evaluation

[0081] Modified polymer plugging and anti-collapse agent / % AV / mPa.s 400mL water + 8% bentonite 71 400mL water + 2% product of Example 1 + 8% bentonite 10 400mL water + 4% product of Example 1 + 8% bentonite 3.5 400mL water + 2% product of Example 2 + 8% bentonite 11 400mL water + 4% product of Example 2 + 8% bentonite 4.5 400mL water + 2% product of comparative example 1 + 8% bentonite 84 400mL water + 4% product of comparative example 1 + 8% bentonite 92 400mL water + 2% product of comparative example 2 + 8% bentonite 91 400mL water + 4% product of comparative example 2 + 8% bentonite 102

[0082] (3) Temperature resistance

[0083] The temperature resistance of the modified polymer plugging and anti-collapse agent was tested in oil-based drilling fluid. The experimental method was to measure the performance of the drilling fluid with the modified polymer plugging and anti-collapse agent after rolling aging at 180°C for 72 hours. The results are shown in Table 4. The results show that the modified polymer plugging and anti-collapse agent has little effect on the rheological properties of the oil-based drilling fluid within 72 hours, and the high-temperature and high-pressure filtration loss reduction rate reaches 60%. The closed filtration loss shows that the plugging effect is long-lasting and effective. This shows that the modified polymer plugging and anti-collapse agent maintains good efficacy at 180°C / 72h and meets the temperature resistance requirements.

[0084] Table 4 Temperature resistance of the products of the examples at 180°C

[0085]

[0086] Note: The base slurry composition is (3 # White oil: 20% calcium chloride aqueous solution = 85:15) + 6% emulsifier + 4% calcium oxide + 2% organic soil + 4% asphalt resin fluid loss reducer (density 1.2g / cm 3 ); emulsifier, Zhongyuan Petroleum Engineering Co., Ltd. (patent No. ZL.201711027059.X, Example 6); organic soil, Zhejiang Fenghong New Materials Co., Ltd. (BS-1C); fluid loss reducer is an oxidized asphalt fluid loss reducer, Shandong Deshunyuan Petroleum Technology Co., Ltd. (OFC).

[0087] From the experimental results, we can know that the characteristics of this product include: temperature resistance up to 180℃, good compatibility with oil-based drilling fluid, obvious filtration reduction and plugging effects, and can be used for plugging high-temperature formations.

[0088] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention, but the present invention is not limited thereto. Those skilled in the art can understand that within the technical concept of the present invention, the technical solution of the present invention can be modified, or some technical features can be combined in any other way. These modifications or combinations do not make the essence of the corresponding technical solution deviate from the spirit and scope of each implementation of the technical solution of the present invention, and should be regarded as the contents disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A modified polymer plugging and anti-collapse agent for drilling fluid, characterized in that: It is obtained by modifying the lipophilic polymer through chloromethylation and amination.

2. The modified polymer plugging and anti-collapse agent for drilling fluid according to claim 1, characterized in that: The lipophilic polymer is selected from one or more of polystyrene, cross-linked polystyrene, polyacrylonitrile-styrene, cross-linked polyacrylonitrile-styrene, polystyrene-methyl methacrylate, cross-linked polystyrene-methyl methacrylate, polyacrylonitrile-butadiene-styrene and cross-linked polyacrylonitrile-butadiene-styrene.

3. The modified polymer plugging and anti-collapse agent for drilling fluid according to claim 1, characterized in that: The oleophilic polymer is industrial waste.

4. A method for preparing a modified polymer plugging and anti-collapse agent for drilling fluid, characterized in that: The following steps are involved: S1) chloromethylating the oleophilic polymer to obtain a chloromethylated polymer; S2) aminate-modifying the chloromethylated polymer to obtain a modified polymer plugging and leak-proofing agent for drilling fluid.

5. The preparation method according to claim 4, characterized in that: The step S1) is specifically as follows: In the presence of a catalyst, the oleophilic polymer and the chloromethylation agent are mixed and reacted in a first organic solvent to obtain a chloromethylation polymer.

6. The preparation method according to claim 5, characterized in that: The catalyst is selected from one or more of P2O5, ZnCl2, SnCl4 and TiCl4; The chloromethylation agent is selected from 1,4-dichloromethoxybutane; The first organic solvent is selected from one or more of dichloromethane, chloroform and carbon tetrachloride.

7. The preparation method according to claim 5, characterized in that: The mass of the catalyst is 0.5 to 4 times the mass of the oleophilic polymer; The mass of the chloromethylation reagent is 2 to 20 times the mass of the lipophilic polymer; The mass of the first organic solvent is 20 to 50 times the mass of the lipophilic polymer.

8. The preparation method according to claim 4, characterized in that: The amination reagent used for the amination modification in step S2) is selected from one or more of trimethylamine, triethylamine and pyridine; the mass of the amination reagent is 2 to 6 times the mass of the chloromethylated polymer; The amination modification is carried out in a second organic solvent; the second organic solvent is selected from one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide and toluene; the mass of the second organic solvent is 2 to 10 times the mass of the chloromethylated polymer.

9. The preparation method according to claim 4, characterized in that: After the amination modification in step S2), granulation is further performed to obtain a modified polymer plugging and leak-proofing agent for drilling fluid; the modified polymer plugging and leak-proofing agent for drilling fluid has a D 50 The particle size is 20~100μm.

10. A drilling fluid, comprising the modified polymer plugging and anti-collapse agent for drilling fluid according to any one of claims 1 to 3 or the modified polymer plugging and anti-collapse agent for drilling fluid prepared by the preparation method of any one of claims 4 to 9.

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