Cellulosic polymers, processes for their preparation, and their use in water-based drilling fluids

Abstract

The present application relates to the field of chemical additives for oilfield drilling, and discloses a cellulose polymer, a preparation method and application thereof, and a water-based drilling fluid.The cellulose polymer comprises an a-cellulose main body and a plurality of substituent groups -R and -CH2COONa, the substituent groups being connected to part of the hydroxyl oxygen contained in the a-cellulose main body; wherein the -R is selected from at least one of -C6H 15 ClNO, -C5H 13 ClN and -C6H 15 ClN; in the polymer, the degree of substitution of -R and -CH2COONa satisfies the following relationship: 0.8≤(DS-CH2COONa+DS ‑R )≤1.6, DS-CH2COONa / DS ‑R =1:(0.05-0.15). The cellulose polymer has the ability to resist metal ions (anti-gel), and is applied to a water-based drilling fluid containing 1% high-concentration multivalent metal salt as a fluid loss additive, so that the API fluid loss of the drilling fluid is less than 16 mL, and the problem that the performance of a common polyanionic cellulose fluid loss additive is invalid in the process of drilling a formation containing high-concentration metal ions can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of chemical additives for oilfield drilling, specifically to a cellulose polymer, its preparation method and application, and a water-based drilling fluid. Background Technology

[0002] Cellulose, a natural polymer, is a linear polymer composed of numerous D-glucopyranoside glycosides linked by β-(1,4) glycosidic bonds. Its advantages of being environmentally friendly, inexpensive, and easy to process have led to its widespread application in chemical production. Polyanionic cellulose, a water-soluble anionic cellulose ether, is prepared from natural fibers such as cotton through refining, alkalization, and etherification processes. Polyanionic cellulose is commonly used as a filtration loss reducer in oil drilling, improving mud cake quality, controlling filtration loss, and regulating the rheological properties of drilling fluids.

[0003] Polyanionic cellulose's main chemical component is sodium carboxymethyl cellulose. When dissolved in water, it dissociates into long-chain molecules containing carboxyl groups, hence the name anionic cellulose ether. Currently, in water-based drilling, when drilling into highly salinized formations, sodium carboxymethyl cellulose, which originally functions to lift, thicken, and reduce filtration loss, undergoes a gel reaction with metal ions (iron, copper, aluminum, lanthanum, cerium, nickel, zinc, etc.) in the formation after dissociation in the aqueous phase. This reaction forms complexes, creating a three-dimensional network gel structure, severely reducing the effectiveness of sodium carboxymethyl cellulose in water-based drilling fluids.

[0004] Therefore, developing anti-gelling cellulose-based filtration loss reducers is of great significance for expanding the application effect and scope of this type of environmentally friendly drilling aid. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing polyanionic cellulose filtration loss reducers having insufficient resistance to metal ions and being prone to reacting with metal ions to form gels, which seriously affects their performance in water-based drilling fluids. This invention provides a cellulose polymer, its preparation method and application, and a water-based drilling fluid.

[0006] To achieve the above objectives, a first aspect of the present invention provides a cellulose polymer comprising: an α-cellulose matrix and a plurality of substituent groups -R and -CH2COONa, wherein the substituent groups are connected to some of the hydroxyl oxygen contained in the α-cellulose matrix;

[0007] Wherein, -R is selected from -C6H 15 ClNO, -C5H 13 ClN and -C6H 15 At least one of ClN;

[0008] In the polymer, the degree of substitution of -R and -CH2COONa satisfies the following relationship:

[0009] 0.8≤(DS-CH2COONa+DS -R )≤1.6, DS-CH2COONa / DS -R =1:(0.05-0.15).

[0010] A second aspect of the present invention provides a method for preparing a cellulose polymer, comprising:

[0011] (1) Alkali treatment of cellulose raw material in the presence of organic solvent and alkaline solution to obtain alkalized cellulose;

[0012] (2) The alkalized cellulose is subjected to a first etherification treatment in the presence of a first etherifying agent to obtain a first product;

[0013] (3) The first etherified product is activated in the presence of an activator to obtain the second product;

[0014] (4) In the presence of a second etherifying agent, the second product is subjected to a second etherification treatment to obtain a cellulose polyether polymer.

[0015] The third aspect of the present invention provides a cellulose polymer obtained by the method described in the second aspect above.

[0016] A fourth aspect of the present invention provides a water-based drilling fluid containing the cellulose polymer described in the first or third aspect above.

[0017] The fifth aspect of the present invention provides the application of the cellulose polymers described in the first or third aspect above as filtration loss reducers in drilling fluids.

[0018] Through the above technical solution, this invention employs a specific molecular structure design, simultaneously introducing anionic substituents -CH2COONa and specific cationic substituents into the α-cellulose matrix to replace some hydrogen atoms in the hydroxyl groups of the α-cellulose matrix. The degree of substitution of the anionic and cationic substituents is optimized and adjusted to obtain a modified cellulose polymer. The cellulose polymer provided by this invention utilizes the electrostatic repulsion between its specific cationic groups and metal ions (iron ions, copper ions, aluminum ions, lanthanum ions, cerium ions, nickel ions, zinc ions, etc.), significantly reducing the gelation effect between the cellulose polymer and these metal ions, thus exhibiting anti-metal ion (anti-gel) capabilities. This allows it to maintain its performance well in water-based environments containing metal ions. When used as a filtration loss reducer in water-based drilling fluids containing 1% high-concentration polyvalent metal salts, the cellulose polymer provided by this invention can achieve an API filtration loss of less than 16 mL, effectively solving the problem of performance failure of ordinary polyanionic cellulose filtration loss reducers in drilling processes involving formations with high concentrations of metal ions. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 The infrared spectrum of the cellulose polymer prepared in Example 1 of the present invention. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0023] In a first aspect, the present invention provides a cellulose polymer comprising: an α-cellulose matrix and a plurality of substituent groups -R and -CH2COONa, wherein the substituent groups are connected to some of the hydroxyl oxygen contained in the α-cellulose matrix;

[0024] Wherein, -R is selected from -C6H 15 ClNO, -C5H 13ClN and -C6H 15 At least one of ClN;

[0025] In the polymer, the degree of substitution of -R and -CH2COONa satisfies the following relationship:

[0026] 0.8≤(DS-CH2COONa+DS -R )≤1.6, DS-CH2COONa / DS -R =1:(0.05-0.15).

[0027] According to the present invention, the α-cellulose matrix is ​​a known α-cellulose matrix with a cyclic repeating chain segment structure composed of C and O, as shown in formula (1).

[0028]

[0029] In formula (1), a secondary hydroxyl group is attached to the carbon atom at position 2 and the carbon atom at position 3 of the six-membered heterocycle composed of C and O, and a primary hydroxyl group is attached to the carbon atom at position 6. The cellulose polymer provided by the present invention is obtained by replacing the hydroxyl hydrogen in some of the hydroxyl groups attached to the α-cellulose host with -R and -CH2COONa (that is, after substitution, -R and -CH2COONa are respectively attached to hydroxyl oxygen). In the present invention, there is no particular limitation on the position of the hydroxyl hydrogen replaced by -R and -CH2COONa, which can be any hydroxyl hydrogen on any hydroxyl group in the above formula (1), as long as the degree of substitution of -R and -CH2COONa in the cellulose polymer can satisfy the following relationship, specifically: 0.8 ≤ (DS-CH2COONa+DS -R )≤1.6, DS-CH2COONa / DS -R =1:(0.05-0.15).

[0030] In this invention, the hydroxyl oxygen refers to the oxygen atom contained in the hydroxyl group (i.e., "-OH"), and the hydroxyl hydrogen refers to the hydrogen atom contained in the hydroxyl group.

[0031] In this invention, the degree of substitution (DS) refers to the number of hydroxyl hydrogens replaced by substituted groups in each carbon-oxygen six-membered heterocyclic structural unit of the cellulose polymer, which can be determined by the ash method specified in GB / T5005-2010 (Drilling Fluid Materials Specification).

[0032] According to the present invention, for the -R, wherein -C6H 15 The structural formula of ClNO is shown in formula (2), -C5H 13 The structural formula of ClN is shown in equation (3), -C6H 15 The structural formula of ClN is shown in formula (4);

[0033]

[0034] In formulas (2), (3) and (4), * indicates the position where the substituent group is attached to the hydroxyl oxygen.

[0035] In the cellulose polymers provided by this invention, -R is a cationic substituent. The inventors of this invention have discovered that by substituting hydroxyl hydrogen into the α-cellulose matrix, simultaneously introducing anionic substituents -CH2COONa and specific cationic substituents, and utilizing the electrostatic repulsion between the cationic groups and polyvalent metal ions (iron ions, copper ions, aluminum ions, lanthanum ions, cerium ions, nickel ions, zinc ions, etc.), the complexation reaction between the polymer and these metal ions in water can be significantly suppressed, thereby preventing gel formation. This allows the polymer to be less affected by high concentrations of metal ions in aqueous environments, i.e., it possesses excellent resistance to metal ions. According to a preferred embodiment of this invention, -R is selected from -C6H... 15 ClNO and / or -C6H 15 ClN can give the cellulose polymer better resistance to metal ions.

[0036] According to the present invention, in the cellulosic polymer, the degree of substitution of -R and -CH2COONa, in addition to satisfying the relationship defined above, further includes DS-CH2COONa / DS -R =1:(0.1-0.15), which can further enhance the resistance of the cellulose polymer to metal ions.

[0037] According to the present invention, the degree of polymerization of the cellulosic polymer is 70-2600. Excessive polymerization will result in excessively high apparent viscosity of the cellulosic polymer, while excessively low polymerization will result in excessively low apparent viscosity, affecting its thickening and shearing effects. In this invention, the degree of polymerization can be determined by the method specified in GB / T 9107-1999 (Refined Cotton).

[0038] According to the present invention, the apparent viscosity of the cellulose polymer is 10-2000 mPa·s. In the present invention, the apparent viscosity can be determined by the method specified in GB / T 5005-2010 (Drilling Fluid Materials Specification).

[0039] The cellulose polymer provided by this invention exhibits excellent thickening and water-retention effects when dissolved in water, and possesses superior resistance to metal ions, exhibiting minimal complexation reactions with metal ions. When used as a filtration loss reducer in water-based drilling fluids, it effectively solves the problem of performance failure of ordinary polyanionic cellulose filtration loss reducers in drilling processes involving formations with high concentrations of metal ions. Specifically, applying the cellulose polymer provided by this invention to a water-based drilling fluid containing 1% high-concentration polyvalent metal salts (where the metal ions in the polyvalent metal salts can be iron, copper, aluminum, lanthanum, cerium, nickel, or zinc ions) (i.e., the content of the polyvalent metal salts in the water-based drilling fluid reaches 1% by weight) can achieve an API filtration loss of less than 16 mL.

[0040] According to a preferred embodiment of the present invention, the polymer comprises: an α-cellulose matrix and a plurality of substituent groups -C6H 15 ClNO and -CH2COONa, and -C6H 15 ClNO and -CH2COONa connect some of the hydroxyl oxygens contained in the α-cellulose matrix; wherein, -C6H 15 The degree of substitution of ClNO and -CH2COONa satisfies: 1.3 ≤ (DS-CH2COONa + DS-C6H) 15 ClNO)≤1.6, DS-CH2COONa / DS-C6H 15 ClNO = 1:(0.1-0.12). The cellulose polymer of this preferred embodiment, when used as a filtration loss reducer in water-based drilling fluids containing 1% high-concentration polyvalent metal salts, can achieve an API filtration loss of less than 10 mL.

[0041] A second aspect of the present invention provides a method for preparing a cellulose polymer, comprising:

[0042] (1) Alkali treatment of cellulose raw material in the presence of organic solvent and alkaline solution to obtain alkalized cellulose;

[0043] (2) The alkalized cellulose is subjected to a first etherification treatment in the presence of a first etherifying agent to obtain a first product;

[0044] (3) The first etherified product is activated in the presence of an activator to obtain the second product;

[0045] (4) In the presence of a second etherifying agent, the second product is subjected to a second etherification treatment to obtain a cellulose polyether polymer.

[0046] According to the present invention, in step (1), the cellulose raw material is selected from refined cotton (the main component is α-cellulose) or cellulose extracts containing α-cellulose other than refined cotton.

[0047] According to the present invention, when the cellulose raw material is a cellulose extract containing α-cellulose other than refined cotton, it is preferable to purify the cellulose raw material before the alkalization treatment so that the content of α-cellulose in the purified raw material reaches 90-99% by weight.

[0048] According to the present invention, preferably, the polymer of α-cellulose in the cellulose raw material is 300-2600.

[0049] According to the present invention, in step (1), the organic solvent is preferably an alcohol solvent, and more preferably ethanol and / or isopropanol.

[0050] According to the present invention, in step (1), the alkaline solution can be a conventional alkaline aqueous solution used for alkalizing cellulose, such as an aqueous solution of sodium hydroxide. Preferably, the concentration of the aqueous solution of sodium hydroxide is 30-45% by weight.

[0051] According to the present invention, in step (1), in order to obtain a better alkalization effect, preferably, the weight ratio of the organic solvent: the solute alkali (e.g., NaOH) in the alkali solution: the cellulose raw material is (8-30): (0.6-1.6): 1.

[0052] According to the present invention, in step (1), in order to better control the alkalization process and obtain better treatment effect, water can be added to the reaction system according to the reaction progress of the alkalization process. The operation and the amount of water added can be carried out using methods and parameters known in the art, and the present invention does not have any particular limitation on this.

[0053] According to the present invention, in step (1), the alkalization treatment can be carried out using conventional operating methods, and the present invention does not have any particular limitations on this. Preferably, the conditions for the alkalization treatment include: a temperature of 10-30°C and a time of 1-2 hours.

[0054] According to the present invention, in step (2), the first etherifying agent is selected from at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CAS No.: 3327-22-8), 3-chloropropyltrimethylammonium chloride (CAS No.: 1936-95-4), and 2-chloroethyltrimethylammonium chloride (CAS No.: 999-81-5), more preferably 3-chloro-2-hydroxypropyltrimethylammonium chloride and / or 3-chloropropyltrimethylammonium chloride, and most preferably 3-chloro-2-hydroxypropyltrimethylammonium chloride.

[0055] According to the present invention, in step (2), preferably, the weight ratio of the first etherifying agent to the cellulose raw material in step (1) is (0.1-0.25):1.

[0056] According to the present invention, in step (2), for the first etherification treatment, the alkalized cellulose can be mixed with a first etherifying agent and subjected to an etherification reaction at a certain temperature. By substituting the hydroxyl hydrogen, a specific cationic substituent group is introduced into the α-cellulose matrix to obtain the first product. Preferably, the conditions for the first etherification treatment include: a temperature of 40-80°C and a time of 0.5-3 h. More preferably, the conditions for the first etherification treatment include: a temperature of 50-75°C and a time of 1-2 h.

[0057] According to the present invention, in step (3), preferably, the activator is selected from at least one of triethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium chloride and benzyltriethylammonium chloride.

[0058] According to the present invention, in step (3), preferably, the weight ratio of the activator to the cellulose raw material in step (1) is (0.02-0.1):1.

[0059] According to the present invention, in step (3), for the activation treatment, the first product can be mixed with an activator and activated at a certain temperature, so that the hydroxyl groups on the cellulose molecular ring that did not participate in the etherification during the first etherification treatment maintain high reactivity, thereby obtaining the second product. Preferably, the activation treatment conditions include: a temperature of 30-50°C and a time of 0.5-1 h.

[0060] According to the present invention, in step (4), the second etherifying agent is selected from chloroacetic acid and / or sodium chloroacetate.

[0061] According to the present invention, in step (4), preferably, the weight ratio of the second etherifying agent to the cellulose raw material in step (1) is (0.5-1.8):1.

[0062] According to the present invention, in step (4), for the second etherification treatment, the second product can be mixed with the second etherifying agent and the etherification reaction can be carried out at a certain temperature to further introduce -CH2COONa into the α-cellulose matrix by substituting hydroxyl hydrogen. Preferably, the conditions for the second etherification treatment include: a temperature of 50-80°C and a time of 1-3 hours.

[0063] According to a preferred embodiment of the present invention, the conditions for the second etherification treatment include: reacting at a temperature of 50-55°C for 1-1.5 hours, followed by heating and reacting at 75-80°C for 1-1.5 hours.

[0064] According to the present invention, the method for preparing the cellulose polymer further includes neutralizing, filtering, washing and drying the product system obtained after the second etherification treatment to obtain the cellulose polyether polymer.

[0065] The third aspect of the present invention provides a cellulose polymer obtained by the method described in the second aspect above.

[0066] According to the present invention, the structure, composition and properties of the cellulose polymers prepared by the method described in the second aspect are the same as those of the cellulose polymers described in the first aspect of the present invention, and will not be repeated here.

[0067] A fourth aspect of the present invention provides a water-based drilling fluid containing the cellulose polymer described in the first or third aspect above.

[0068] The water-based drilling fluid provided by this invention contains the cellulose polymer provided by this invention, which gives the water-based drilling fluid excellent resistance to metal ions and enables it to maintain a low filtration loss during drilling in formations containing high concentrations of metal ions. According to this invention, preferably, based on the total weight of the water-based drilling fluid, the content of the cellulose polymer in the water-based drilling fluid is 0.2-3% by weight.

[0069] The fifth aspect of the present invention provides the application of the cellulose polymers described in the first or third aspect above as filtration loss reducers in drilling fluids.

[0070] The present invention will be described in detail below through preparation examples and embodiments. Unless otherwise specified, the preparation examples and embodiments described below are conventional methods; the reagents and materials mentioned are commercially available unless otherwise specified.

[0071] Example 1

[0072] (1) Refined cotton (containing α-cellulose with a degree of polymerization of 300-500), isopropanol, and NaOH aqueous solution (concentration of 45% by weight) were added to a four-necked flask and stirred. The mixture was then alkalized at 10°C for 2 hours to obtain alkalized cellulose.

[0073] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0074] (2) Add an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 1.5 h to obtain the first product;

[0075] The weight ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the refined cotton in step (1) is 0.15:1.

[0076] (3) Add tetraethylammonium chloride to the product obtained in step (2) and activate it at 50°C for 1 hour to obtain the second product;

[0077] The weight ratio of tetraethylammonium chloride to refined cotton in step (1) is 0.05:1.

[0078] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and continue etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P1).

[0079] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.9:1.

[0080] The apparent viscosity of P1 was 140 mPa·s and the degree of polymerization was 370, according to the test results.

[0081] Infrared spectroscopy was performed on P1, and the results are as follows: Figure 1 As shown, Figure 1 As can be seen, 1636cm -1 1322cm -1 The presence of a characteristic absorption peak near the P1 region indicates that -C6H 15 ClNO and -CH2COONa are linked to hydroxyl oxygen;

[0082] In P1, (DS-CH2COONa+DS-C6H) 15 ClNO)=1.60, DS-CH2COONa / DS-C6H 15 ClNO = 1:0.12.

[0083] Example 2

[0084] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 300-500), isopropanol, and NaOH aqueous solution (45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0085] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0086] (2) Add an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 1 hour to obtain the first product;

[0087] The weight ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the refined cotton in step (1) is 0.1:1.

[0088] (3) Add tetraethylammonium chloride to the product obtained in step (2) and activate it at 50°C for 1 hour to obtain the second product;

[0089] The weight ratio of tetraethylammonium chloride to refined cotton in step (1) is 0.05:1.

[0090] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P2).

[0091] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.9:1.

[0092] The apparent viscosity of P2 was 110 mPa·s, and the degree of polymerization was 350, according to the test results.

[0093] In P2, (DS-CH2COONa+DS-C6H) 15 ClNO)=1.36, DS-CH2COONa / DS-C6H 15 ClNO = 1:0.10.

[0094] Example 3

[0095] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 500-800), isopropanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0096] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0097] (2) Add an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 3 hours to obtain the first product;

[0098] The weight ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride to the refined cotton in step (1) is 0.2:1.

[0099] (3) Add tetraethylammonium chloride to the product obtained in step (2) and activate it at 50°C for 1 hour to obtain the second product;

[0100] The weight ratio of tetraethylammonium chloride to refined cotton in step (1) is 0.05:1.

[0101] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P3).

[0102] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.9:1.

[0103] The apparent viscosity of P3 was 230 mPa·s, and the degree of polymerization was 620, according to the test results.

[0104] In P3, (DS-CH2COONa+DS-C6H) 15 ClNO)=1.28, DS-CH2COONa / DS-C6H 15 ClNO = 1:0.15.

[0105] Example 4

[0106] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 500-800), isopropanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0107] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0108] (2) Add an aqueous solution of 3-chloropropyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 40°C for 3 hours to obtain the first product;

[0109] The weight ratio of 3-chloropropyltrimethylammonium chloride aqueous solution to refined cotton in step (1) is 0.2:1.

[0110] (3) Tetrabutylammonium chloride was added to the product obtained in step (2), and the product was activated at 50°C for 0.5 h to obtain the second product;

[0111] The weight ratio of tetramethylammonium chloride to refined cotton in step (1) is 0.08:1;

[0112] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P4).

[0113] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.9:1.

[0114] The apparent viscosity of P4 was 260 mPa·s, and the degree of polymerization was 590, according to the test results.

[0115] In P4, (DS-CH2COONa+DS-C6H) 15 ClN)=1.23, DS-CH2COONa / DS-C6H 15 ClN = 1: 0.14.

[0116] Example 5

[0117] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 500-800), isopropanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0118] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0119] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 2 hours to obtain the first product;

[0120] The weight ratio of 2-chloroethyltrimethylammonium chloride to the refined cotton in step (1) is 0.25:1;

[0121] (3) Add benzyltrimethylammonium chloride to the product obtained in step (2) and activate it at 30°C for 0.5 h to obtain the second product;

[0122] The weight ratio of benzyltrimethylammonium chloride to refined cotton in step (1) is 0.09:1;

[0123] (4) Add sodium chloroacetate in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The product obtained is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P5).

[0124] The weight ratio of sodium chloroacetate to refined cotton in step (1) is 1.12:1.

[0125] The apparent viscosity of P5 was 350 mPa·s and the degree of polymerization was 580, according to the test results.

[0126] In P5, (DS-CH2COONa+DS-C5H) 13 ClN)=1.20, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.15.

[0127] Example 6

[0128] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 1000-1400), ethanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 30°C for 1 hour to obtain alkalized cellulose.

[0129] The weight ratio of ethanol: solute NaOH: refined cotton is 24:1.6:1.

[0130] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 80°C for 0.5 h to obtain the first product;

[0131] The weight ratio of 2-chloroethyltrimethylammonium chloride to the refined cotton in step (1) is 0.15:1;

[0132] (3) Triethylammonium chloride was added to the product obtained in step (2), and the product was activated at 50°C for 1 hour to obtain the second product;

[0133] The weight ratio of triethylammonium chloride to refined cotton in step (1) is 0.02:1;

[0134] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 0.5 h. Then raise the temperature to 75°C and perform etherification treatment for 0.5 h to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 h to obtain cellulose polymer (denoted as P6).

[0135] The weight ratio of chloroacetic acid to refined cotton in step (1) is 1.8:1.

[0136] The apparent viscosity of P6 was tested to be 620 mPa·s, and the degree of polymerization was 1100.

[0137] In P6, (DS-CH2COONa+DS-C5H) 13 ClN)=0.95, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.05.

[0138] Example 7

[0139] (1) Refined cotton (containing α-cellulose with a degree of polymerization of 2000-2600), isopropanol, and NaOH aqueous solution (concentration of 30% by weight) were added to a four-necked flask and stirred. The mixture was then alkalized at 20°C for 1 hour to obtain alkalized cellulose.

[0140] The weight ratio of isopropanol: solute NaOH: refined cotton is 8:0.6:1.

[0141] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 1 hour to obtain the first product;

[0142] The weight ratio of 2-chloroethyltrimethylammonium chloride to the refined cotton in step (1) is 0.15:1;

[0143] (3) Add benzyltriethylammonium chloride to the product obtained in step (2) and activate it at 50°C for 1 hour to obtain the second product;

[0144] The weight ratio of benzyltriethylammonium chloride to refined cotton in step (1) is 0.1:1.

[0145] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 2 hours. Then raise the temperature to 80°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P7).

[0146] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.5:1.

[0147] According to the test, the apparent viscosity of P7 is 2000 mPa·s, and the degree of polymerization is 2320.

[0148] In P7, (DS-CH2COONa+DS-C5H) 13 ClN)=0.92, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.06.

[0149] Example 8

[0150] (1) The rice straw is purified to obtain purified material (the content of α-cellulose in the purified material is 92% by weight, and the degree of polymerization of the α-cellulose is 300-500). The above purified material, isopropanol, and NaOH aqueous solution (concentration of 45% by weight) are added to a four-necked flask and stirred. The mixture is alkalized at 20°C for 1 hour to obtain alkalized cellulose.

[0151] The weight ratio of isopropanol: solute NaOH: purified material is 30:0.81:1.

[0152] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 1 hour to obtain the first product;

[0153] The weight ratio of 2-chloroethyltrimethylammonium chloride to the purified material in step (1) is 0.12:1;

[0154] (3) Add tetrabutylammonium bromide to the product obtained in step (2) and activate it at 50°C for 1 hour to obtain the second product;

[0155] The weight ratio of tetraethylammonium chloride to the purified material in step (1) is 0.05:1;

[0156] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as P8).

[0157] The weight ratio of chloroacetic acid to the purified material in step (1) is 0.9:1.

[0158] Tests showed that P8 has an apparent viscosity of 10 mPa·s and a degree of polymerization of 70.

[0159] In P8, (DS-CH2COONa+DS-C5H) 13 ClN)=1.52, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.09.

[0160] Comparative Example 1

[0161] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 500-800), ethanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0162] The weight ratio of ethanol: solute NaOH: refined cotton is 24:0.81:1.

[0163] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 0.5 h to obtain the first product;

[0164] The weight ratio of 2-chloroethyltrimethylammonium chloride to the refined cotton in step (1) is 0.15:1;

[0165] (3) Triethylammonium chloride was added to the product obtained in step (2), and the product was activated at 50°C for 1 hour to obtain the second product;

[0166] The weight ratio of triethylammonium chloride to refined cotton in step (1) is 0.02:1;

[0167] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 h, then raise the temperature to 70°C and perform etherification treatment for 0.5 h to obtain the product system; then cool the product system, neutralize with acetic acid, filter, wash with 90% wt% ethanol aqueous solution and filter again, and vacuum dry the obtained product at 80°C for 24 h to obtain cellulose polymer (denoted as D1);

[0168] The weight ratio of chloroacetic acid to refined cotton in step (1) is 1.8:1.

[0169] The apparent viscosity of D1 was tested to be 72 mPa·s, and the degree of polymerization was 590.

[0170] In D1, (DS-CH2COONa+DS-C5H) 13 ClN)=0.78, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.05.

[0171] Comparative Example 2

[0172] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 300-500), isopropanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0173] The weight ratio of isopropanol:solute NaOH:refined cotton is 24:0.81:1.

[0174] (2) Add tetraethylammonium chloride activator to the product obtained in step (1) and perform activation treatment at 50°C for 1 hour to obtain the activated product;

[0175] The weight ratio of tetraethylammonium chloride activator to refined cotton in step (1) is 0.05:1.

[0176] (3) Add chloroacetic acid in isopropanol solution to the activated product obtained in step (2), and perform etherification treatment at 50°C for 1 h. Then raise the temperature to 75°C and perform etherification treatment for 1 h to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 h to obtain cellulose polymer (denoted as D2).

[0177] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.9:1.

[0178] The apparent viscosity of D2 was 10 mPa·s, and the degree of polymerization was 330, according to the test results.

[0179] In D2, DS-C6H 15 ClNO=0, DS-CH2COONa=1.2.

[0180] Comparative Example 3

[0181] (1) Add refined cotton (containing α-cellulose with a degree of polymerization of 500-800), ethanol, and NaOH aqueous solution (concentration of 45% by weight) into a four-necked flask and stir to mix. Then, perform alkalization treatment at 20°C for 1 hour to obtain alkalized cellulose.

[0182] The weight ratio of ethanol: solute NaOH: refined cotton is 24:0.81:1.

[0183] (2) Add an aqueous solution of 2-chloroethyltrimethylammonium chloride to the product obtained in step (1) and perform etherification treatment at 50°C for 0.5 h to obtain the first product;

[0184] The weight ratio of 2-chloroethyltrimethylammonium chloride to the refined cotton in step (1) is 0.08:1.

[0185] (3) Triethylammonium chloride was added to the product obtained in step (2), and the product was activated at 50°C for 1 hour to obtain the second product;

[0186] The weight ratio of triethylammonium chloride to refined cotton in step (1) is 0.02:1;

[0187] (4) Add chloroacetic acid in isopropanol solution to the product obtained in step (3), and perform etherification treatment at 50°C for 1 hour. Then raise the temperature to 75°C and perform etherification treatment for 1 hour to obtain the product system. Then cool the product system, neutralize it with acetic acid, filter it, wash it with 90% wt% ethanol aqueous solution and filter it again. The obtained product is vacuum dried at 80°C for 24 hours to obtain cellulose polymer (denoted as D3).

[0188] The weight ratio of chloroacetic acid to refined cotton in step (1) is 0.6:1.

[0189] The apparent viscosity of D3 was 102 mPa·s, and the degree of polymerization was 570, according to the test results.

[0190] In D3, (DS-CH2COONa+DS-C5H) 13 ClN)=0.95, DS-CH2COONa / DS-C5H 13 ClN = 1: 0.02.

[0191] Test case

[0192] The performance of the cellulose polymers P1-P8 and D1-D3 prepared in Examples 1-8 and Comparative Examples 1-3, as well as conventional commercially available polyanionic cellulose (LV-PAC, purchased from Shandong Baifeng New Material Technology Co., Ltd.), was tested.

[0193] 1. Evaluation of resistance to metal ions (anti-gelling)

[0194] (1) Take 10 mL of deionized water and slowly add 0.5 g of P1-P8, D1-D3 and LV-PAC respectively under stirring to completely dissolve them and form a viscous solution;

[0195] (2) Add 5 drops of FeCl3 aqueous solution (the concentration of FeCl3 aqueous solution is 0.5 mol / L) to the above viscous solution, stir well and let stand for 1 h;

[0196] (3) Observe the gelation of the sample. The results are shown in Table 1.

[0197] Table 1

[0198] Test sample Whether a gel forms <![CDATA[0.5 g of P1 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> no <![CDATA[0.5 g of P2 + 10 mL of deionized water + 5 drops of FeCl3 aqueous solution]]> no <![CDATA[0.5 g P3 + 10 mL deionized water + 5 drops of aqueous FeCl3 solution]]> no <![CDATA[0.5 g of P4 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> no <![CDATA[0.5 g of P5 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> no <![CDATA[0.5 g P6 + 10 mL deionized water + 5 drops of FeCl3 aqueous solution]]> no <![CDATA[0.5 g of P7 + 10 mL of deionized water + 5 drops of FeCl3 aqueous solution]]> no <![CDATA[0.5 g of P8 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> no <![CDATA[0.5 g of D1 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> yes <![CDATA[0.5 g of D2 + 10 mL of deionized water + 5 drops of aqueous FeCl3 solution]]> yes <![CDATA[0.5 g D3 + 10 mL deionized water + 5 drops of FeCl3 aqueous solution]]> yes <![CDATA[0.5 g LV-PAC + 10 mL deionized water + 5 drops of aqueous FeCl3 solution]]> yes

[0199] As shown in Table 1, the cellulose polymers containing specific anions and cations provided by this invention exhibit excellent resistance to metal ions, and are unlikely to undergo complexation reactions with polyvalent metal ions such as iron ions to form gels in aqueous environments. In comparison, the antigel properties of D1-D3 and LV-PAC are inferior to those of P1-P8.

[0200] 2. Evaluation of Filtration Loss Reduction Performance

[0201] (1) Add 42g of sea salt (the composition of the sea salt meets GB / T 5005-2010) to 1L of deionized water to prepare a sea salt solution;

[0202] (2) Take 358g of the above sea salt solution, add 35g KCl and 1g NaHCO3, stir to dissolve fully, then add 28g API standard evaluation soil (purchased from Beijing Mining Engineering Research Institute), and stir to dissolve fully;

[0203] (3) Add 2g of P1-P8, D1-D3 and LV-PAC as filtration loss reducers to the above-prepared slurry and stir until completely dissolved;

[0204] (4) Add 3.5g FeCl3·6H2O, 2.0g CuCl2·2H2O and 1g anhydrous AlCl3 to the slurry obtained in step (3), stir until completely dissolved, and then cure the resulting slurry (referred to as F1-F8 and DF1-DF4 respectively, wherein the filtration loss reducer added to DF4 is LV-PAC) in a sealed container at 25±1℃ for 16h.

[0205] (5) After curing, the API filtration loss of the slurry at 690±35kPa was tested according to GB / T 5005-2010 (Note: the filtration loss of the slurry within 7.5-30min was recorded as V1, and the final API filtration loss was twice V1). The results are shown in Table 2.

[0206] Table 2

[0207]

[0208]

[0209] As shown in Table 2, the cellulose polymers containing specific anions and cations provided by this invention, when used as filtration reducers in water-based drilling fluid systems containing polyvalent metal ions such as iron and copper ions, exhibit less influence from high concentrations of metal ions on their filtration performance. This results in an API filtration loss of drilling fluid of less than 16 mL, meeting the filtration performance requirements of cellulose filtration reducers in GB / T 5005-2010. In contrast, the filtration reducers used in DF1-DF4 readily complex with polyvalent metal ions in water, leading to their inactivation and resulting in high filtration loss in the system.

[0210] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A cellulose polymer, characterized in that, The polymer comprises: an α-cellulose matrix and a plurality of substituents -R and -CH2COONa, wherein the substituents are connected to some of the hydroxyl oxygen contained in the α-cellulose matrix; Wherein, -R is selected from -C6H 15 ClNO, -C5H 13 ClN and -C6H 15 At least one of ClN; In the polymer, the degree of substitution of -R and -CH2COONa satisfies the following relationship: 0.8≤(DS +DS -R )≤1.6,DS / DS -R =1:(0.05-0.15)。 2. The cellulose polymer according to claim 1, wherein, -R is selected from -C6H 15 ClNO and / or C6H 15 ClN; And / or, DS / DS -R =1: (0.1-0.15).

3. The cellulosic polymer according to claim 1 or 2, wherein, The degree of polymerization of the cellulose polymer is 70-2600.

4. The cellulosic polymer according to claim 1 or 2, wherein, The apparent viscosity of the cellulose polymer is 10-2000 mPa·s.

5. The cellulosic polymer according to claim 3, wherein, The apparent viscosity of the cellulose polymer is 10-2000 mPa·s.

6. A method for preparing the cellulose polymer according to any one of claims 1-5, characterized in that, include: (1) In the presence of organic solvent and alkaline solution, cellulose raw material is alkalized to obtain alkalized cellulose; (2) The alkalized cellulose is subjected to a first etherification treatment in the presence of a first etherifying agent to obtain a first product; (3) The first etherified product is activated in the presence of an activator to obtain the second product; (4) In the presence of a second etherifying agent, the second product is subjected to a second etherification treatment to obtain a cellulose polyether polymer; Wherein, the first etherifying agent is selected from at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 3-chloropropyltrimethylammonium chloride and 2-chloroethyltrimethylammonium chloride; The activator is selected from at least one of triethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium chloride, and benzyltriethylammonium chloride; the second etherifying agent is selected from chloroacetic acid and / or sodium chloroacetate.

7. The method according to claim 6, wherein, In step (1), the cellulose raw material is selected from refined cotton or cellulose extracts containing α-cellulose other than refined cotton; And / or, the alkaline solution is an aqueous solution of sodium hydroxide; And / or, the weight ratio of the organic solvent: the solute base in the alkaline solution: the cellulose raw material is (8-30):(0.6-1.6):1; And / or, the conditions for the alkalization treatment include: a temperature of 10-30°C and a time of 1-2 hours.

8. The method according to claim 7, wherein, In step (1), the degree of polymerization of α-cellulose in the cellulose raw material is 300-2600.

9. The method according to any one of claims 6-8, wherein, In step (2), The weight ratio of the first etherifying agent to the cellulose raw material is (0.1-0.25):1; And / or, the conditions for the first etherification treatment include: a temperature of 40-80°C and a time of 0.5-3 hours.

10. The method according to any one of claims 6-8, wherein, In step (3), the weight ratio of the activator to the cellulose raw material is (0.02-0.1):1; And / or, the activation treatment conditions include: a temperature of 30-50°C and a time of 0.5-1h.

11. The method according to any one of claims 6-8, wherein, In step (4), The weight ratio of the second etherifying agent to the cellulose raw material is (0.5-1.8):1; And / or, the conditions for the second etherification treatment include: a temperature of 50-80°C and a time of 1-3 hours.

12. A water-based drilling fluid comprising the cellulose polymer as described in any one of claims 1-5.

13. The use of the cellulose polymer according to any one of claims 1-5 as a filtration loss reducer in drilling fluids.

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