Copolymer and preparation method and application thereof

Abstract

The invention relates to the technical field of drilling fluid treating agents, in particular to a copolymer and a preparation method and application thereof. The copolymer contains a molecular chain A from humate, a molecular chain B from lignosulfonate, a molecular chain C from procyanidine, a linking group D from an aldehyde cross-linking agent and a cross-linking point M from a metal salt cross-linking agent, wherein the molecular chain A, the molecular chain B and the molecular chain C are connected through a linking group D and / or a crosslinking point M, and the linking group D is bonded with carbon atoms on benzene rings contained in the molecular chain A, the molecular chain B and the molecular chain C respectively; the cross-linking point M and oxygen atoms on hydroxyl groups or carbonyl groups contained in the molecular chain A, the molecular chain B and the molecular chain C form a multi-element cyclic structure through coordinate bonds. The copolymer disclosed by the invention has temperature resistance, adsorbability, dispersity and environmental protection property at the same time, and can be used as a high-temperature-resistant environment-friendly viscosity reducer for water-based drilling fluid.

Description

Technical Field

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

[0002] Viscosity reducers are indispensable drilling fluid treatment agents in the drilling process, and they play a very important role in adjusting the rheological properties of drilling fluids. During the drilling process, the intrusion and dispersion of solid particles can easily cause a significant increase in the viscosity and shear force of the drilling fluid system. Although solid control equipment can remove some large solid particles in the drilling fluid, it has limited effect in adjusting the rheological properties of the drilling fluid. Therefore, the method of adding viscosity reducers is often used in field operations to improve the rheological properties of the drilling fluid.

[0003] With the deepening of oil and gas exploration and development, oil and gas exploration has developed into deep formations, the well depth has gradually increased, and the formation conditions encountered have become increasingly complex. For deep wells or high-pressure drilling in oil and gas wells, the required drilling fluid needs to meet the characteristics of high density. Due to the addition of a large amount of solid phase weighting agents, the friction between particles in the drilling fluid is enhanced, the viscosity and shear force of the drilling fluid are significantly increased, and the fluidity is reduced; at the same time, during the drilling process, due to the contamination of the drilling fluid by electrolytes and drill cuttings in the formation, the drilling fluid will be thickened, which is manifested as increased viscosity and increased shear force. In the process, the pump pressure will increase or jam, the resistance of the drill tool will increase, and accidents are prone to occur. Therefore, most of the viscosity reducer products commonly used on site can no longer meet the drilling needs.

[0004] The existing drilling fluid viscosity reducers at home and abroad are mainly divided into two categories: modified natural polymers and synthetic polymers. Among them, synthetic polymer viscosity reducers have excellent temperature resistance, but are difficult to degrade, so they are not environmentally friendly enough; modified natural polymer viscosity reducers are mainly grafted with acrylamide polymers on natural polymers such as lignin, which sacrifices some environmental performance while pursuing higher temperature resistance. It can be seen that the current drilling fluid viscosity reducers have a contradiction between environmental protection and temperature resistance. Although traditional modified natural macromolecular viscosity reducers such as modified lignin, modified humic acid, and modified tannin have good environmental protection, they are not resistant to temperature and cannot meet the needs of high-temperature deep well and ultra-deep well drilling. Synthetic polymer viscosity reducers have high temperature resistance, but poor biodegradability and high cost.

[0005] In view of this, the development of low-cost, environmentally friendly viscosity reducers that are suitable for resistant to high temperature and high salt is a technical problem that needs to be solved urgently at this stage. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems that the water-based drilling fluid viscosity reducer in the prior art cannot take into account both temperature resistance and environmental protection, and to provide a copolymer and a preparation method and application thereof. The copolymer of the present invention is non-toxic, easily degradable, and will not cause harm to the environment. It can be used as a high-temperature resistant and environmentally friendly viscosity reducer for water-based drilling fluid, and can play an excellent viscosity reducing role in a high-temperature environment at the bottom of a well.

[0007] After extensive research, the inventors of the present invention found that by moderately cross-linking humates rich in various polar groups, lignin sulfonates rich in sulfonic acid groups, and proanthocyanidins rich in phenolic hydroxyl groups, the cross-linked products can simultaneously have temperature resistance, adsorption, dispersibility, and environmental protection, and are particularly suitable for use as high-temperature resistant and environmentally friendly viscosity reducers for drilling fluids.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a copolymer, which contains: a molecular chain A from humate, a molecular chain B from lignin sulfonate, a molecular chain C from proanthocyanidin, a connecting group D from an aldehyde crosslinking agent, and a crosslinking point M from a metal salt crosslinking agent; wherein the molecular chain A, the molecular chain B and the molecular chain C are connected by the connecting group D and / or the crosslinking point M, and the connecting group D is bonded to the carbon atom on the benzene ring contained in each of the molecular chain A, the molecular chain B and the molecular chain C; the crosslinking point M forms a polycyclic structure with the oxygen atom on the hydroxyl or carbonyl group contained in each of the molecular chain A, the molecular chain B and the molecular chain C through a coordination bond.

[0009] A second aspect of the present invention provides a method for preparing a copolymer, the preparation method comprising:

[0010] 1) subjecting humate, lignin sulfonate and proanthocyanidin to a first cross-linking reaction by using an aldehyde cross-linking agent to obtain an intermediate product;

[0011] 2) subjecting the intermediate product to a second cross-linking reaction using a metal salt cross-linking agent to obtain the copolymer.

[0012] The third aspect of the present invention provides a copolymer obtained by the aforementioned preparation method.

[0013] A fourth aspect of the present invention provides use of the aforementioned copolymer in water-based drilling fluid; preferably, the copolymer is used as a drilling fluid viscosity reducer.

[0014] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0015] 1) The copolymer of the present invention uses three natural degradable materials, namely humate, lignin sulfonate and proanthocyanidin, as raw materials, so that it has the characteristics of non-toxicity, easy degradation and environmental friendliness. Humate is rich in various active groups such as carboxyl, phenolic hydroxyl, carbonyl, etc., taking into account adsorption and hydration, and can be used as the main structure of the viscosity reducer; lignin sulfonate is rich in sulfonic acid groups, which can make the product form a thick hydration layer on the bentonite surface of the drilling fluid, thereby dismantling the bentonite grid structure and reducing the viscosity of the drilling fluid; proanthocyanidin is rich in phenolic hydroxyl groups, which gives the product strong adsorption on the bentonite surface and is not easy to desorb at high temperature. The organic combination of these three raw materials can make the product have excellent viscosity reduction and adsorption properties at the same time under high temperature environment.

[0016] 2) The present invention moderately crosslinks phenolic hydroxyl-rich humate, sulfonic acid-rich lignin sulfonate and phenolic hydroxyl-rich proanthocyanidin, so that the crosslinked product has temperature resistance, adsorption, dispersibility and environmental protection, and is particularly suitable for use as a high-temperature resistant and environmentally friendly viscosity reducer for water-based drilling fluid; multiple crosslinking between humate, lignin sulfonate and proanthocyanidin molecules is achieved through aldehyde crosslinking agents and metal salt crosslinking agents, thereby forming a multi-ring structure, which has a more solid molecular skeleton and can further improve the temperature resistance of the product.

[0017] 3) The copolymer of the present invention can be used as a viscosity reducer for water-based drilling fluids, has excellent viscosity reduction performance at high temperatures, temperature resistance of more than 180°C, viscosity reduction rate of more than 90%, biological toxicity>190000mg / L, biodegradability BOD5 / COD Cr >0.20. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the infrared spectrum of copolymer A1 obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] The first aspect of the present invention provides a copolymer, which contains: a molecular chain A from humate, a molecular chain B from lignin sulfonate, a molecular chain C from proanthocyanidin, a connecting group D from an aldehyde crosslinking agent, and a crosslinking point M from a metal salt crosslinking agent; wherein the molecular chain A, the molecular chain B and the molecular chain C are connected through the connecting group D and / or the crosslinking point M, and the connecting group D is bonded to the carbon atom on the benzene ring contained in each of the molecular chain A, the molecular chain B and the molecular chain C; the crosslinking point M forms a polycyclic structure with the oxygen atom on the hydroxyl or carbonyl group contained in each of the molecular chain A, the molecular chain B and the molecular chain C through a coordination bond.

[0021] In the present invention, the connecting group D is bonded to the carbon atoms on the benzene rings contained in the molecular chains A, B and C, preferably to the active carbon atoms on the benzene rings, and the active carbon atoms are preferably located at the ortho position of the phenolic hydroxyl group or the sulfonic acid group and have a position that can provide bonding.

[0022] In the present invention, crosslinking includes but is not limited to: crosslinking of two molecules from humate by an aldehyde crosslinking agent, crosslinking of two molecules from lignin sulfonate by an aldehyde crosslinking agent, crosslinking of two molecules from proanthocyanidins with an aldehyde crosslinking agent, crosslinking of molecules from humate with molecules from lignin sulfonate and aldehyde crosslinking agents, crosslinking of molecules from humate with molecules from proanthocyanidins with aldehyde crosslinking agents, crosslinking of molecules from lignin sulfonate with molecules from proanthocyanidins with aldehyde crosslinking agents, crosslinking of molecules from humate with molecules from lignin sulfonate and molecules from proanthocyanidins with aldehyde crosslinking agents.

[0023] In the present invention, each cross-linking point M forms a multi-membered ring structure with the oxygen atoms on the hydroxyl group or carbonyl group contained in each of the molecular chains A, molecular chain B and molecular chain C through coordination bonds, wherein the multi-membered ring structure includes but is not limited to: metal ions and the oxygen atoms on the hydroxyl group or carbonyl group contained in each of the molecular chains A, molecular chain B and molecular chain C chelate to form a five-membered ring complex or a six-membered ring complex.

[0024] The invention uses three natural degradable materials, namely humate, lignin sulfonate and proanthocyanidin, as raw materials, so that the humate has the characteristics of being non-toxic, easily degradable and environmentally friendly.

[0025] The invention moderately cross-links sulfonic acid group-rich lignin sulfonate with phenolic hydroxyl-rich proanthocyanidin, so that the cross-linked product has temperature resistance, adsorption, dispersibility and environmental protection, and is particularly suitable for use as a high-temperature resistant and environmentally friendly viscosity reducer for water-based drilling fluid; multiple cross-linking between humate, lignin sulfonate and proanthocyanidin molecules is achieved through aldehyde cross-linking agents and metal salt cross-linking agents, thereby forming a multi-ring structure, which has a stronger molecular skeleton and can further improve the temperature resistance of the product.

[0026] In the present invention, humate is rich in carboxyl, phenolic hydroxyl, carbonyl and other active groups, taking into account adsorption and hydration, and can be used as the main structure of the viscosity reducer; lignin sulfonate is rich in sulfonic acid groups, which can make the product form a thick hydration layer on the bentonite surface of the drilling fluid, thereby dismantling the bentonite grid structure and reducing the viscosity of the drilling fluid; proanthocyanidins are rich in phenolic hydroxyl groups, giving the product strong adsorption on the bentonite surface, and are not easy to desorb at high temperatures. After the three raw materials are organically combined, the product can have excellent viscosity reduction and adsorption at the same time under high temperature environment.

[0027] In the present invention, humate is used as a raw material, which can reduce the cost of the product because humic acid is relatively cheap. On the other hand, humic acid has a high carboxyl -COOH content and can provide a thicker hydration film after being adsorbed on the surface of clay particles, thereby improving the viscosity reduction effect.

[0028] In some embodiments of the present invention, the weight ratio of the molecular chain A, the molecular chain B and the molecular chain C is 1:0.25-1:0.3-1, preferably 1:0.5-1:0.4-1.

[0029] In some embodiments of the present invention, the weight ratio of the total weight of the molecular chain A, the molecular chain B and the molecular chain C to the connecting group D is 10-30:1, preferably 15-25:1, and more preferably 18-22:1.

[0030] In some embodiments of the present invention, the weight ratio of the total weight of the molecular chain A, the molecular chain B and the molecular chain C to the cross-linking point M is 2-10:1, preferably 3-7:1, and more preferably 4-6:1.

[0031] In the present invention, the above structure and composition can be determined by nuclear magnetic resonance, infrared, GPC, elemental analysis and the like, or by the amount of humate, lignin sulfonate, proanthocyanidin, aldehyde crosslinking agent and metal salt crosslinking agent added during preparation.

[0032] In some embodiments of the present invention, the humate is selected from one or more of sodium humate, potassium humate and calcium humate; preferably sodium humate and / or potassium humate, more preferably sodium humate.

[0033] In some embodiments of the present invention, the weight average molecular weight of the humate is 500-20000 g / mol, preferably 1000-12000 g / mol, and more preferably 4000-6000 g / mol.

[0034] In some embodiments of the present invention, the lignin sulfonate is selected from one or more of sodium lignin sulfonate, potassium lignin sulfonate and calcium lignin sulfonate; preferably sodium lignin sulfonate and / or potassium lignin sulfonate, more preferably sodium lignin sulfonate.

[0035] In some embodiments of the present invention, the sulfonation degree of the lignin sulfonate is 0.3-1, preferably 0.6-1, and more preferably 0.8-1. The higher the sulfonation degree of the lignin sulfonate, the higher the number of sulfonic acid groups it carries, so that the product has better hydration ability and is not easy to dehydrate at high temperature, so that the cross-linked polymer has better high-temperature viscosity reduction performance.

[0036] In some embodiments of the present invention, the weight average molecular weight of the lignin sulfonate is 2000-10000 g / mol, preferably 4000-8000 g / mol, and more preferably 6000-8000 g / mol.

[0037] In some embodiments of the present invention, the proanthocyanidins are selected from one or more anthocyanin extracts of grapes, hawthorn, peanuts, ginkgo, thuja rohanata, thuja juniper, blueberries and black beans, preferably anthocyanin extracts of grapes and / or hawthorn, more preferably anthocyanin extracts of grapes.

[0038] Proanthocyanidins are a general term for a large class of polyphenolic compounds widely found in plants, and their common feature is that they can produce anthocyanidins when heated in an acidic medium. The proanthocyanidins in the present invention refer to anthocyanidin extracts extracted from the above substances.

[0039] In some embodiments of the present invention, the weight average molecular weight of the proanthocyanidins is 500-3000 g / mol, preferably 1000-2000 g / mol, and more preferably 1500-2000 g / mol.

[0040] In some embodiments of the present invention, the linking group D is selected from one or more of -CH2-, -CH2OCH2-, -CH(CH3)-, -CH(CH3)O(CH3)CH-, and -CH2-CH2-.

[0041] In the present invention, the connecting group D that cross-links humate with lignin sulfonate and proanthocyanidin can be a dimethylene bridge, for example, -CH2-, -CH(CH3)-, -CH2-CH2-; it can also be a dimethylene ether bridge, for example, -CH2OCH2-, -CH(CH3)O(CH3)CH-.

[0042] In some embodiments of the present invention, the aldehyde crosslinking agent is a water-soluble low-level aldehyde, preferably selected from one or more of formaldehyde, acetaldehyde, glyoxal and glutaraldehyde, more preferably formaldehyde and / or acetaldehyde, further preferably formaldehyde.

[0043] In some embodiments of the present invention, the metal salt cross-linking agent is a transition metal compound, preferably selected from one or more of low-valent compounds of iron, low-valent compounds of tin, low-valent compounds of zirconium and low-valent compounds of titanium, more preferably low-valent compounds of iron and / or low-valent compounds of tin, and further preferably low-valent compounds of iron. Among them, the low-valent compound of iron can be selected from ferrous sulfate, ferrous chloride, and ferrous nitrate, and the low-valent compound of tin can be selected from stannous sulfate, stannous chloride, and stannous nitrate.

[0044] In some embodiments of the present invention, the weight average molecular weight of the copolymer is 5000-40000 g / mol, preferably 10000-20000 g / mol.

[0045] In some embodiments of the present invention, the crosslinking degree of the copolymer is 3-5 wt %.

[0046] In the present invention, the degree of crosslinking = mass of the crosslinking agent / (mass of the crosslinking monomer+mass of the crosslinking agent)*100%.

[0047] In some embodiments of the present invention, the copolymer has a temperature resistance of ≥180°C, a viscosity reduction rate of 10wt% bentonite slurry of ≥90%, a biological toxicity of >190000mg / L, and a biodegradability of BOD5 / COD Cr >0.20.

[0048] A second aspect of the present invention provides a method for preparing a copolymer, the preparation method comprising:

[0049] 1) subjecting humate, lignin sulfonate and proanthocyanidin to a first cross-linking reaction by using an aldehyde cross-linking agent to obtain an intermediate product;

[0050] 2) subjecting the intermediate product to a second cross-linking reaction using a metal salt cross-linking agent to obtain the copolymer.

[0051] In the present invention, the selection of humate, lignin sulfonate, proanthocyanidin, aldehyde cross-linking agent and metal salt cross-linking agent is the same as that of the first aspect. Please refer to the previous description for details, which will not be repeated here.

[0052] In some embodiments of the present invention, the weight ratio of humate, lignin sulfonate and proanthocyanidin is 1:0.25-1:0.5-1, preferably 1:0.5-1:0.75-1.

[0053] In some embodiments of the present invention, the total mass concentration of humate, lignin sulfonate and proanthocyanidin in water is 10%-40%, preferably 20%-30%.

[0054] In some embodiments of the present invention, the weight ratio of the total weight of the lignin sulfonate and proanthocyanidins to the aldehyde cross-linking agent is 10-30:1, preferably 15-25:1, and more preferably 18-22:1.

[0055] In some embodiments of the present invention, the weight ratio of the total weight of the lignin sulfonate and proanthocyanidins to the metal salt cross-linking agent is 2-10:1, preferably 3-7:1, and more preferably 4-6:1.

[0056] In some embodiments of the present invention, the conditions of the first cross-linking reaction include: pH 3-11, preferably 7-11, more preferably 8-10; temperature 60-100°C, preferably 70-90°C, more preferably 75-85°C; time 1-4h, preferably 1.5-3h, more preferably 2-2.5h.

[0057] In some embodiments of the present invention, the conditions of the second cross-linking reaction include: temperature of 60-100°C, preferably 70-90°C, more preferably 75-85°C; time of 0.25-2h, preferably 0.5-1.5h, more preferably 0.5-1h.

[0058] In the present invention, the first cross-linking reaction can be carried out under acidic and alkaline conditions. The first cross-linking reaction is a covalent cross-linking reaction, in which humate, lignin sulfonate and proanthocyanidin are covalently cross-linked through an aldehyde cross-linking agent; the second cross-linking reaction is a complex cross-linking reaction, in which the first cross-linking reaction product is chelated through a metal salt cross-linking agent to form a polycyclic structure.

[0059] Specifically, the above preparation method comprises the following steps:

[0060] S1, dissolving humate, lignin sulfonate and proanthocyanidin in water and mixing to form a solution, adjusting the pH of the solution with an alkali metal hydroxide; then heating to a specified temperature, adding an aldehyde cross-linking agent, and stirring to keep the temperature within a certain temperature range for a certain time;

[0061] S2. After the reaction is completed, a metal salt cross-linking agent is immediately added to the reaction product obtained in step S1, and the reaction is continued at the same temperature for a certain period of time under stirring;

[0062] S3, drying the reaction product obtained in step S2 at 80-100° C. to constant weight, and then crushing and sieving the obtained solid product.

[0063] Wherein, the alkali metal hydroxide can be selected from sodium hydroxide or potassium hydroxide, preferably sodium hydroxide. The water can be selected from tap water, deionized water or distilled water, preferably deionized water.

[0064] In the present invention, the structure and composition of the copolymer can be determined by NMR, IR, GPC, elemental analysis and other measurement methods, or by the amount of raw materials added during preparation.

[0065] The third aspect of the present invention provides a copolymer obtained by the aforementioned preparation method.

[0066] A fourth aspect of the present invention provides use of the aforementioned copolymer in water-based drilling fluid; preferably, the copolymer is used as a drilling fluid viscosity reducer.

[0067] The copolymer of the present invention can be used as a high temperature resistant and environmentally friendly viscosity reducer for water-based drilling fluids, has excellent viscosity reduction performance at high temperatures, has a temperature resistance of more than 180°C, a viscosity reduction rate of more than 88%, biological toxicity>190000mg / L, and a biodegradability of BOD5 / COD Cr >0.20.

[0068] The present invention will be described in detail below through examples.

[0069] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0070] In the following examples, the composition of the obtained copolymer is determined by the feed amount of each raw material.

[0071] Method for determining biological toxicity: Determine in accordance with the "Technical Evaluation Method for Environmental Protection of Water-soluble Oilfield Chemicals" (SY / T6788-2020).

[0072] Method for determining biodegradation rate: Determine in accordance with the "Technical Evaluation Method for Environmental Protection of Water-soluble Oilfield Chemicals" (SY / T6788-2020).

[0073] Example 1

[0074] 1) Add 14 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0075] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added and stirred at 80° C. for 2 h;

[0076] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A1.

[0077] The weight average molecular weight of copolymer A1 was 21500 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 196700mg / L, biodegradation rate BOD5 / COD Cr is 0.26.

[0078] like Figure 1 The infrared spectrum of copolymer A1 is shown in the figure. It can be seen from the spectrum that when sodium humate is cross-linked with sodium lignin sulfonate and proanthocyanidins at high temperature, in addition to the original lignin sulfonate at 1602cm -1 、1511cm -1 、1421cm -1 There is an aromatic absorption peak at 1211cm -1 、1037cm -1 In addition to the absorption peaks of ether, phenolic hydroxyl or sulfonic acid groups, in the viscosity reducer spectrum, 1691cm -1 A strong absorption peak appeared at 1029cm -1 A new absorption peak appeared at 1444cm -1 The absorption peak at 1353cm is enhanced. According to the absorption law of the shearing, out-of-plane swing and in-plane swing vibration of CH2 in the methylene bridge bond (-CH2), it can be determined that there is a methylene bridge bond in the synthetic product; in addition, the product spectrum at 1353cm -1 The peak at 40° was strengthened, indicating that there was a methylene ether bridge. The above infrared spectrum analysis results show that aldehydes caused cross-linking between sodium humate, lignin sulfonate and proanthocyanidin natural polymers.

[0079] Through the feeding, it can be known that in copolymer A1, molecular chain A comes from sodium humate, molecular chain B comes from sodium lignin sulfonate, molecular chain C comes from grape seed proanthocyanidins, connecting group D comes from formaldehyde, and cross-linking point M comes from ferrous sulfate; wherein, the weight ratio of molecular chain A, molecular chain B and molecular chain B is 1:0.71:0.43; the ratio of the total weight of molecular chain A, molecular chain B and molecular chain C to the weight of connecting group C is 20.7:1; the ratio of the total weight of molecular chain A, molecular chain B and molecular chain C to the weight of cross-linking point M is 6.2:1.

[0080] Example 2

[0081] 1) Add 10 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 10 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0082] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 2 h;

[0083] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A2.

[0084] The weight average molecular weight of copolymer A2 was 19870 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 196100mg / L, biodegradation rate BOD5 / COD Cr is 0.26.

[0085] Example 3

[0086] 1) Add 15 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 5 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0087] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 2 h;

[0088] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A3.

[0089] The weight average molecular weight of copolymer A3 was 16870 g / mol, the crosslinking degree was 3 wt%, and the biological toxicity EC 50 210500mg / L, biodegradation rate BOD5 / COD Cr is 0.27.

[0090] Example 4

[0091] 1) Add 14 g of sodium humate (weight average molecular weight 10,000), 10 g of sodium lignin sulfonate (weight average molecular weight 4,000, degree of sulfonation 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 3,000) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0092] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 2.78 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 2 h;

[0093] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A4.

[0094] The weight average molecular weight of copolymer A4 was 17560 g / mol, the crosslinking degree was 3.3 wt%, and the biological toxicity EC 50 201800mg / L, biodegradation rate BOD5 / COD Cr is 0.27.

[0095] Example 5

[0096] 1) Add 14 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0097] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added and stirred at 80° C. for 2 h;

[0098] 3) After step 2), 2.5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A5.

[0099] The weight average molecular weight of copolymer A5 was 16320 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 205400mg / L, biodegradation rate BOD5 / COD Cr is 0.26.

[0100] Example 6

[0101] 1) Add 14 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0102] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 2 h;

[0103] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 98° C. for 0.5 h to obtain copolymer A6.

[0104] The weight average molecular weight of copolymer A6 was 18960 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 196700mg / L, biodegradation rate BOD5 / COD Cr is 0.24.

[0105] Example 7

[0106] 1) Add 14 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 9 with NaOH;

[0107] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 4 h;

[0108] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A7.

[0109] The weight average molecular weight of copolymer A7 was 18130 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 193200mg / L, biodegradation rate BOD5 / COD Cr is 0.24.

[0110] Example 8

[0111] 1) Add 14 g of sodium humate (weight average molecular weight 4000), 10 g of sodium lignin sulfonate (weight average molecular weight 8000, sulfonation degree 0.8), 6 g of grape seed proanthocyanidins (grape seed extract, weight average molecular weight 1500) and 100 g of deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 7 with NaOH;

[0112] 2) The mixed monomer solution was heated to 80° C. in a constant temperature water bath, and then 4.16 g of formaldehyde (concentration 36%) was added, and the mixture was stirred and reacted at 80° C. for 2 h;

[0113] 3) After step 2), 5 g of ferrous sulfate was added to the mixed monomer solution, and the reaction was continued at 80° C. for 0.5 h to obtain copolymer A8.

[0114] The weight average molecular weight of copolymer A8 was 20250 g / mol, the crosslinking degree was 4 wt%, and the biological toxicity EC 50 221300mg / L, biodegradation rate BOD5 / COD Cr is 0.25.

[0115] Example 9

[0116] 1) Add 14 g potassium humate (weight average molecular weight 10000), 10 g calcium lignin sulfonate (weight average molecular weight 5000, sulfonation degree 0.8), 6 g black bean proanthocyanidins (black bean extract, weight average molecular weight 3000) and 80 g deionized water to a three-necked flask equipped with a thermometer and a stirrer, stir until completely dissolved, and then adjust the pH to 4 with KOH;

[0117] 2) The mixed monomer solution was heated to 100° C. in a constant temperature water bath, and then 4.16 g of glyoxal (concentration 36%) was added and stirred at 100° C. for 1 h;

[0118] 3) After step 2), 5 g of stannous sulfate was added to the mixed monomer solution, and the reaction was continued at 70° C. for 2 h to obtain copolymer A9.

[0119] The weight average molecular weight of copolymer A9 was 19350 g / mol, the crosslinking degree was 5 wt%, and the biological toxicity EC 50 213300mg / L, biodegradation rate BOD5 / COD Cr It is 0.23.

[0120] Comparative Example 1

[0121] The method described in Example 1 was followed, except that in step 1), no humate was added to obtain copolymer D1.

[0122] Comparative Example 2

[0123] The method described in Example 1 was followed, except that in step 1), no grape seed proanthocyanidins were added to obtain copolymer D2.

[0124] Comparative Example 3

[0125] The method described in Example 1 was followed, except that in step 1), sodium lignin sulfonate was not added to obtain copolymer D3.

[0126] Comparative Example 4

[0127] Sodium ferrochrome lignin sulfonate produced by Hubei Xinrunde Chemical Co., Ltd. was used as polymer D4.

[0128] Test Case

[0129] 1) Prepare two portions of bentonite-based slurry. Add 40.0 g of bentonite for drilling fluid test slurry (in accordance with SY / T 5490) and 1.4 g of anhydrous sodium carbonate to 400 mL of distilled water. Stir at high speed for 20 min, stopping at least twice to scrape off the adhesions on the container wall, and seal and place at room temperature for 24 h.

[0130] 2) Take one portion of the bentonite base slurry and add 4.0g of sample A1. Place the sample slurry and base slurry in a high-temperature roller furnace and roll at 180°C for 16 hours. After cooling, stir at a high speed of 10000r / min for 5 minutes. Use a six-speed rotation viscometer to measure the viscosity reading of the base slurry at 100r / min. The viscosity reduction rate of copolymer A1 is calculated according to formula (1);

[0131]

[0132] Where:

[0133] Y——relative inhibition rate, %;

[0134] ——Base slurry reading at 100r / min;

[0135] ——Reading value containing sample slurry at 100r / min.

[0136] 3) According to steps 1) and 2), the viscosity reduction rates of viscosity reducer samples A2-A9 and D1-D4 were measured. The results are shown in Table 1.

[0137] Table 1 Measurement results

[0138]

[0139] It can be seen from the results in Table 1 that when the polymer of the present invention is added as a viscosity reducer to a 10% concentration of bentonite-based slurry, the viscosity reduction rate after high-temperature aging at 180°C for 16 hours can be as high as 90% or more, which is much better than the iron-chromium lignin sulfonate commonly used in China, indicating that the polymer of the present invention has good viscosity reduction and temperature resistance, and can effectively improve the rheological properties of water-based drilling fluids in high temperature environments.

[0140] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A copolymer, It is characterized in that The copolymer contains: a molecular chain A from humate, a molecular chain B from lignin sulfonate, a molecular chain C from proanthocyanidin, a connecting group D from an aldehyde crosslinking agent, and a crosslinking point M from a metal salt crosslinking agent; wherein the molecular chain A, the molecular chain B and the molecular chain C are connected through the connecting group D and / or the crosslinking point M, and the connecting group D is bonded to the carbon atom on the benzene ring contained in each of the molecular chain A, the molecular chain B and the molecular chain C; the crosslinking point M forms a multi-ring structure with the oxygen atom on the hydroxyl group or carbonyl group contained in each of the molecular chain A, the molecular chain B and the molecular chain C through a coordination bond.

2. The copolymer according to claim 1, in, The weight ratio of the molecular chain A, the molecular chain B and the molecular chain C is 1:0.25-1:0.3-1, preferably 1:0.5-1:0.4-1; And / or, the ratio of the total weight of the molecular chain A, the molecular chain B and the molecular chain C to the weight of the connecting group D is 10-30:1, preferably 15-25:1; And / or, the ratio of the total weight of the molecular chain A, the molecular chain B and the molecular chain C to the weight of the cross-linking point M is 2-10:1, preferably 3-7:

1.

3. The copolymer according to claim 1 or 2, in, The humate is selected from one or more of sodium humate, potassium humate and calcium humate; preferably sodium humate and / or potassium humate; And / or, the weight average molecular weight of the humate is 500-20000 g / mol, preferably 1000-12000 g / mol.

4. The copolymer according to any one of claims 1 to 3, in, The lignin sulfonate is selected from one or more of sodium lignin sulfonate, potassium lignin sulfonate and calcium lignin sulfonate; preferably sodium lignin sulfonate and / or potassium lignin sulfonate; and / or, the sulfonation degree of the lignin sulfonate is 0.3-1, preferably 0.6-1; And / or, the weight average molecular weight of the lignin sulfonate is 2000-10000 g / mol, preferably 4000-8000 g / mol.

5. The copolymer according to any one of claims 1 to 4, in, The proanthocyanidins are selected from one or more anthocyanidin extracts of grapes, hawthorn, peanuts, ginkgo, thuja sutchuenensis, thuja sutchuenensis, blueberries and black beans, preferably anthocyanidin extracts of grapes and / or hawthorn; And / or, the weight average molecular weight of the proanthocyanidins is 500-3000 g / mol, preferably 1000-2000 g / mol.

6. The copolymer according to any one of claims 1 to 5, in, The connecting group D is selected from -CH 2 -、-CH 2 OCH 2 -、-CH(CH 3 )-、-CH(CH 3 )O(CH 3 )CH-、-CH 2 -CH 2 -One or more.

7. The copolymer according to any one of claims 1 to 6, in, The aldehyde cross-linking agent is a low-level aldehyde soluble in water, preferably one or more selected from formaldehyde, acetaldehyde, glyoxal and glutaraldehyde.

8. The copolymer according to any one of claims 1 to 7, in, The metal salt cross-linking agent is a transition metal compound, preferably one or more selected from low-valent compounds of iron, low-valent compounds of tin, low-valent compounds of zirconium and low-valent compounds of titanium.

9. The copolymer according to any one of claims 1 to 8, in, The weight average molecular weight of the copolymer is 5000-40000 g / mol, preferably 10000-20000 g / mol; and / or, the crosslinking degree of the copolymer is 3-5wt%; And / or, the copolymer has a temperature resistance of ≥180°C, a viscosity reduction rate of 10wt% bentonite slurry of ≥90%, a biological toxicity of >190000mg / L, and a biodegradability of BOD 5 / COD Cr >0.

20.

10. A method for preparing a copolymer, It is characterized in that The preparation method comprises: 1) subjecting humate, lignin sulfonate and proanthocyanidin to a first cross-linking reaction by using an aldehyde cross-linking agent to obtain an intermediate product; 2) subjecting the intermediate product to a second cross-linking reaction using a metal salt cross-linking agent to obtain the copolymer.

11. The preparation method according to claim 10, in, The weight ratio of humate, lignin sulfonate and proanthocyanidin is 1:0.25-1:0.5-1, preferably 1:0.5-1:0.75-1; and / or, the total mass concentration of the humates, lignin sulfonates and proanthocyanidins in water is 10%-40%, preferably 20%-30%; and / or, the weight ratio of the total weight of the lignin sulfonate and proanthocyanidins to the aldehyde cross-linking agent is 10-30:1, preferably 15-25:1; And / or, the weight ratio of the total weight of the lignin sulfonate and proanthocyanidins to the metal salt cross-linking agent is 2-10:1, preferably 3-7:

1.

12. The preparation method according to claim 10 or 11, in, The conditions of the first cross-linking reaction include: pH 3-11, preferably 7-11; temperature 60-100° C., preferably 70-90° C.; time 1-4 h, preferably 1.5-3 h; And / or, the conditions of the second cross-linking reaction include: temperature of 60-100° C., preferably 70-90° C.; time of 0.25-2 h, preferably 0.5-1.5 h.

13. The copolymer obtained by the preparation method according to any one of claims 10 to 12.

14. Use of the copolymer according to any one of claims 1 to 9 and 13 in water-based drilling fluid; preferably, the copolymer is used as a drilling fluid viscosity reducer.

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