阅读说明：本技术 一种钻井液用耐超高温抗盐降滤失剂及其制备方法 (Ultrahigh-temperature-resistant salt-resistant filtrate reducer for drilling fluid and preparation method thereof ) 是由 刘妍 于 2020-12-15 设计创作，主要内容包括：本发明公开了一种钻井液用耐超高温抗盐降滤失剂及其制备方法,涉及钻井技术领域,解决了现有降滤失剂耐高温性能差、渗透率高的问题,其技术方案要点是：主要由以下原料制备而成：甲基丙烯酸缩水甘油酯、丙烯酰胺单体、交联剂、偶联剂、余量为水；将甲基丙烯酸缩水甘油酯单体、丙烯酰胺单体反应合成二元共聚物；将二元共聚物、交联剂键合交联成一次网络共聚物；将一次网络共聚物、偶联剂键合交联成二次网络共聚物；将二次网络共聚物经干燥、粉碎、过筛处理后得到降滤失剂。本发明通过将两种单体经过聚合、交联形成双线型的共聚物,其网络结构可呈现一定空间结构,整体结构的稳定性得以提示,能够耐250℃的高温,其渗透率低,粘度高。(The invention discloses an ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid and a preparation method thereof, relates to the technical field of drilling, solves the problems of poor high temperature resistance and high permeability of the existing filtrate reducer, and has the technical scheme key points that: the health-care food is mainly prepared from the following raw materials: glycidyl methacrylate, an acrylamide monomer, a cross-linking agent, a coupling agent and the balance of water; reacting a glycidyl methacrylate monomer and an acrylamide monomer to synthesize a binary copolymer; bonding and crosslinking the binary copolymer and the crosslinking agent into a primary network copolymer; bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; and drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. According to the invention, two monomers are polymerized and crosslinked to form a double-linear copolymer, the network structure of the double-linear copolymer can present a certain space structure, the stability of the whole structure is prompted, the double-linear copolymer can resist the high temperature of 250 ℃, and the double-linear copolymer has low permeability and high viscosity.)

1. The ultrahigh-temperature-resistant salt-resistant filtrate reducer for the drilling fluid is characterized by being mainly prepared from the following raw materials: glycidyl methacrylate, an acrylamide monomer, a cross-linking agent, a coupling agent and the balance of water;

reacting a glycidyl methacrylate monomer and an acrylamide monomer to synthesize a binary copolymer;

bonding and crosslinking the binary copolymer and the crosslinking agent into a primary network copolymer;

bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer;

and drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

2. The ultrahigh temperature resistant and salt resistant fluid loss additive for drilling fluid as claimed in claim 1, wherein the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively in the following molar percentages: 33.33-44.44%, 5.56-16.67%.

3. The ultrahigh temperature resistant and salt resistant fluid loss additive for drilling fluid as claimed in claim 1, wherein the primary crosslinking sites and the secondary crosslinking sites in the secondary network copolymer are arranged and have the following general structural formula:

wherein n > 1.

4. The ultra-high temperature and salt resistant fluid loss additive for drilling fluid of claim 1, wherein the cross-linking agent is dimethyldichlorosilane.

5. The superhigh temperature resistant and salt resistant fluid loss additive for drilling fluid as set forth in claim 1, wherein the coupling agent is 3- (2, 3-epoxypropoxy) propyltrimethoxysilane.

6. The ultra-high temperature and salt resistant fluid loss additive for drilling fluid as claimed in claim 1, wherein the fluid loss additive has an upper limit value of high temperature resistance of 250 ℃.

7. The preparation method of the ultrahigh-temperature-resistant salt-resistant filtrate reducer for the drilling fluid is characterized by comprising the following steps of:

s1: reacting a glycidyl methacrylate monomer and an acrylamide monomer to synthesize a binary copolymer;

s2: bonding and crosslinking the binary copolymer and the crosslinking agent into a primary network copolymer;

s3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer;

s4: and drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

8. The preparation method of the ultrahigh temperature resistant and salt resistant fluid loss additive for drilling fluid as claimed in claim 7, wherein the preparation of the binary copolymer comprises:

s101: mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion;

s102: continuously introducing nitrogen into the reactor for 5-10min to remove oxygen and use as protective gas;

s103: adding a water-soluble initiator into the reactor, and stirring and polymerizing for 2-3h at the constant temperature of 55-65 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar weight of the sulfate is 120% of that of the acrylamide monomer;

the binary copolymer prepared by step S103 has the following structural formula:

9. the preparation method of the ultrahigh temperature resistant and salt resistant fluid loss additive for drilling fluid as claimed in claim 8, wherein the preparation of the primary network copolymer comprises:

s201: adding a cross-linking agent into the binary copolymer prepared by S1, pressurizing to 0.6-0.8MPa at constant temperature of 35-45 ℃, and carrying out hydrolysis reaction for 1.5-2h, wherein the molar weight of the cross-linking agent is 12.5-50% of that of the acrylamide monomer;

s202: then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate;

the primary network copolymer prepared by step S202 has the following general structural formula:

10. the preparation method of the ultrahigh temperature resistant and salt resistant fluid loss additive for drilling fluid as claimed in claim 9, wherein the preparation of the secondary network copolymer comprises:

s301: adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 1.5-2h at a constant temperature of 45-55 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure, and the molar weight of the coupling agent is 12.5-50% of that of the acrylamide monomer;

s302: and adding the secondary network copolymer into distilled water, diluting, washing, distilling, drying, crushing and sieving to obtain the granular filtrate reducer.

Technical Field

The invention relates to the technical field of drilling, in particular to an ultrahigh temperature resistant and salt resistant filtrate reducer for drilling fluid and a preparation method thereof.

Background

The filtrate reducer is an important drilling fluid treating agent for ensuring the stable performance of the drilling fluid, reducing the filtration loss of harmful liquid to a stratum, stabilizing a well wall and ensuring the well diameter regulation. The high temperature resistance requirement of the conventional fluid loss additive is not lower than 180 ℃, but with the development of oil field drilling and the increase of deep well and ocean drilling projects, the requirement on the fluid loss additive of the drilling fluid is continuously improved so as to meet the new requirements of salt resistance and high temperature resistance, wherein the temperature is higher than 200 ℃, even 240 ℃.

Currently, the fluid loss additives are generally prepared by polymerizing at least one monomer and then forming a polymer having a network structure by using a crosslinking agent or a coupling agent. However, the existing filtrate reducer is polymerized to form a single-line polymer, and then the single-line polymer is directly cascaded to form a network structure, so that the stability of the structure is relatively poor, and the high temperature resistance and the permeability are poor. Therefore, how to research and design the ultrahigh temperature resistant and salt resistant filtrate reducer for the drilling fluid and the preparation method thereof are problems which need to be solved urgently at present.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide an ultrahigh temperature resistant and salt resistant filtrate reducer for drilling fluid and a preparation method thereof.

The technical purpose of the invention is realized by the following technical scheme:

in a first aspect, the ultrahigh temperature resistant and salt resistant filtrate reducer for the drilling fluid is provided, and is mainly prepared from the following raw materials: glycidyl methacrylate, an acrylamide monomer, a cross-linking agent, a coupling agent and the balance of water;

reacting a glycidyl methacrylate monomer and an acrylamide monomer to synthesize a binary copolymer;

bonding and crosslinking the binary copolymer and the crosslinking agent into a primary network copolymer;

bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer;

and drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Further, the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent respectively have the following mole percentages: 33.33-44.44%, 5.56-16.67%.

Further, the primary crosslinking sites and the secondary crosslinking sites in the secondary network copolymer are arranged and have the following structural general formula:

wherein n > 1.

Further, the cross-linking agent is dimethyldichlorosilane.

Further, the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

Further, the high temperature resistance upper limit value of the fluid loss additive is 250 ℃.

In a second aspect, a preparation method of the ultrahigh temperature resistant and salt resistant filtrate reducer for drilling fluid is provided, and comprises the following steps:

s1: reacting a glycidyl methacrylate monomer and an acrylamide monomer to synthesize a binary copolymer;

s2: bonding and crosslinking the binary copolymer and the crosslinking agent into a primary network copolymer;

s3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer;

s4: and drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Further, the preparation of the binary copolymer specifically comprises the following steps:

s101: mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion;

s102: continuously introducing nitrogen into the reactor for 5-10min to remove oxygen and use as protective gas;

s103: adding a water-soluble initiator into the reactor, and stirring and polymerizing for 2-3h at the constant temperature of 55-65 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar weight of the sulfate is 120% of that of the acrylamide monomer;

the binary copolymer prepared by step S103 has the following structural formula:

further, the preparation of the primary network copolymer specifically comprises the following steps:

s201: adding a cross-linking agent into the binary copolymer prepared by S1, pressurizing to 0.6-0.8MPa at constant temperature of 35-45 ℃, and carrying out hydrolysis reaction for 1.5-2h, wherein the molar weight of the cross-linking agent is 12.5-50% of that of the acrylamide monomer;

s202: then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate;

the primary network copolymer prepared by step S202 has the following general structural formula:

further, the preparation of the secondary network copolymer specifically comprises the following steps:

s301: adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 1.5-2h at a constant temperature of 45-55 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure, and the molar weight of the coupling agent is 12.5-50% of that of the acrylamide monomer;

s302: and adding the secondary network copolymer into distilled water, diluting, washing, distilling, drying, crushing and sieving to obtain the granular filtrate reducer.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, two monomers are polymerized and crosslinked to form a double-linear copolymer, the network structure of the double-linear copolymer can present a certain space structure, the stability of the whole structure is prompted, and the double-linear copolymer can resist the high temperature of 250 ℃;

2. according to the invention, the interpenetrating arrangement of the grid structure is carried out in the double-line type network structure through the secondary network copolymer formed after the coupling of the coupling agent, so that the permeability of the filtrate reducer is reduced;

3. according to the invention, the viscosity of the fluid loss additive is enhanced by constructing a network structure through the dimethyldichlorosilane and the 3- (2, 3-epoxypropoxy) propyltrimethoxysilane;

4. according to the invention, through the staggered arrangement of the cross-linking point positions and the coupling point positions, the uniformity of the network structure can be enhanced, the stability of the structure is further improved, and the permeability is reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a graph comparing the results of fluid loss measurements in the examples of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

Example 1

An ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid is mainly prepared from the following raw materials: glycidyl methacrylate, acrylamide monomer, cross-linking agent, coupling agent and the balance of water. Glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. The binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. And bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer. And drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. The cross-linking agent is dimethyl dichlorosilane, and the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The mol percentages of the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively as follows: 33.33%, 16.67%.

The preparation method specifically comprises the following steps:

s1: glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. Mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion; continuously introducing nitrogen into the reactor for 5min to remove oxygen and using the oxygen as protective gas; adding a water-soluble initiator into the reactor, and stirring and polymerizing for 2 hours at the constant temperature of 55 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar amount of the sulfate is 100% of the molar amount of the acrylamide monomer.

S2: the binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. Adding a cross-linking agent into the binary copolymer prepared by S1, and carrying out hydrolysis reaction for 1.5h at the constant temperature of 35 ℃ under the pressure of 0.6 MPa; then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate.

S3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 1.5h at a constant temperature of 45 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure; adding the secondary network copolymer into distilled water, diluting and washing.

S4: and distilling, drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Example 2

An ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid is mainly prepared from the following raw materials: glycidyl methacrylate, acrylamide monomer, cross-linking agent, coupling agent and the balance of water. Glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. The binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. And bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer. And drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. The cross-linking agent is dimethyl dichlorosilane, and the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The mol percentages of the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively as follows: 33.33%, 5.56%.

The preparation method specifically comprises the following steps:

s1: glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. Mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion; continuously introducing nitrogen into the reactor for 5min to remove oxygen and using the oxygen as protective gas; adding a water-soluble initiator into the reactor, and stirring and polymerizing for 2 hours at the constant temperature of 55 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar amount of the sulfate is 100% of the molar amount of the acrylamide monomer.

S2: the binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. Adding a cross-linking agent into the binary copolymer prepared by S1, and carrying out hydrolysis reaction for 1.5h at the constant temperature of 35 ℃ under the pressure of 0.6 MPa; then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate.

S3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 1.5h at a constant temperature of 45 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure; adding the secondary network copolymer into distilled water, diluting and washing.

S4: and distilling, drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Example 3

An ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid is mainly prepared from the following raw materials: glycidyl methacrylate, acrylamide monomer, cross-linking agent, coupling agent and the balance of water. Glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. The binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. And bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer. And drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. The cross-linking agent is dimethyl dichlorosilane, and the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The mol percentages of the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively as follows: 44.44%, 16.67%.

The preparation method specifically comprises the following steps:

s1: glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. Mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion; continuously introducing nitrogen into the reactor for 10min to remove oxygen and using the nitrogen as protective gas; adding a water-soluble initiator into the reactor, and stirring and polymerizing for 3 hours at the constant temperature of 65 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar amount of the sulfate is 120% of the molar amount of the acrylamide monomer.

S2: the binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. Adding a cross-linking agent into the binary copolymer prepared by S1, and carrying out hydrolysis reaction for 2h at constant temperature of 45 ℃ under pressure of 0.8 MPa; then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate.

S3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 2h at the constant temperature of 55 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure; adding the secondary network copolymer into distilled water, diluting and washing.

Example 4

An ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid is mainly prepared from the following raw materials: glycidyl methacrylate, acrylamide monomer, cross-linking agent, coupling agent and the balance of water. Glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. The binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. And bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer. And drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. The cross-linking agent is dimethyl dichlorosilane, and the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The mol percentages of the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively as follows: 44.44%, 5.56%.

The preparation method specifically comprises the following steps:

s1: glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. Mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion; continuously introducing nitrogen into the reactor for 10min to remove oxygen and using the nitrogen as protective gas; adding a water-soluble initiator into the reactor, and stirring and polymerizing for 3 hours at the constant temperature of 65 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar amount of the sulfate is 120% of the molar amount of the acrylamide monomer.

S2: the binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. Adding a cross-linking agent into the binary copolymer prepared by S1, and carrying out hydrolysis reaction for 2h at constant temperature of 45 ℃ under pressure of 0.8 MPa; then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate.

S3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 2h at the constant temperature of 55 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure; adding the secondary network copolymer into distilled water, diluting and washing.

S4: and distilling, drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Example 5

An ultra-high temperature resistant and salt resistant filtrate reducer for drilling fluid is mainly prepared from the following raw materials: glycidyl methacrylate, acrylamide monomer, cross-linking agent, coupling agent and the balance of water. Glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. The binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. And bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer. And drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer. The cross-linking agent is dimethyl dichlorosilane, and the coupling agent is 3- (2, 3-epoxypropoxy) propyl trimethoxy silane.

The mol percentages of the glycidyl methacrylate, the acrylamide monomer, the cross-linking agent and the coupling agent are respectively as follows: 44.44%, 5.56%.

The preparation method specifically comprises the following steps:

s1: glycidyl methacrylate monomer and acrylamide monomer react to synthesize binary copolymer. Mixing glycidyl methacrylate monomer and acrylamide monomer in a ratio of 1: 1, adding the mixture into a reactor according to a molar weight ratio, and emulsifying to form an emulsion; continuously introducing nitrogen into the reactor for 8min to remove oxygen and using the nitrogen as protective gas; adding a water-soluble initiator into the reactor, and stirring and polymerizing for 2.5 hours at the constant temperature of 60 ℃ to obtain a binary copolymer; the water-soluble initiator is sulfate, and the molar amount of the sulfate is 110% of the molar amount of the acrylamide monomer.

S2: the binary copolymer and the cross-linking agent are bonded and cross-linked to form the primary network copolymer. Adding a cross-linking agent into the binary copolymer prepared by S1, and carrying out hydrolysis reaction for 1.8h at constant temperature of 40 ℃ under pressure of 0.7 MPa; then adding an inorganic peroxide initiator to carry out bonding crosslinking reaction to obtain a primary network copolymer, wherein the primary network copolymer is of a double-line type grid structure; the inorganic peroxide initiator is potassium persulfate. The cross-linking agent is equally divided into two parts to be bonded and cross-linked twice, the first bonding and cross-linking can obtain a double-wire grid structure with a sparse cross-linked structure, and the second bonding and cross-linking can obtain a double-layer grid structure with a single-wire type as one layer.

S3: bonding and crosslinking the primary network copolymer and the coupling agent into a secondary network copolymer; adding a coupling agent into the primary network copolymer prepared by S2, and carrying out coupling reaction for 1.8h at a constant temperature of 50 ℃ to obtain a gelatinous secondary network copolymer, wherein the secondary network copolymer is of a double-layer interpenetrating network structure; adding the secondary network copolymer into distilled water, diluting and washing.

S4: and distilling, drying, crushing and screening the secondary network copolymer to obtain the filtrate reducer.

Comparative example 1

Selecting the existing filtrate reducer as a comparison experiment group, wherein the method specifically comprises the following steps: the filtrate reducer is prepared from methanol, deionized water, polyvinylpyrrolidone, acrylamide and stearyl methacrylate.

Experimental validation and analysis

First, measurement of filtration loss

(1) Apparatus and materials

a. A high-speed stirrer: GJ-I type or similar products, the rotating speed is 11000 +/-300 r/min;

b. the aging tank for the drilling fluid comprises: 500mL wide-mouth glass bottle;

c. the balance sensing quantity is 0.01 g;

d. a filter loss instrument: capacity 300-The filtering area is 45.6 +/-0.6 cm²；

e. Filter paper: a what man No. 50 filter paper or the like;

f. oven: (160- + 300) ± 2 ℃;

g. a dryer;

h. standard sample separation sieve: the aperture of the sieve pore is 0.42 cm;

I. roller heating furnace: controlling the temperature within the range of 0-300 ℃ and controlling the temperature sensitivity to +/-3 ℃, and carrying out aging tank;

J. evaluation soil: chemical purity;

t, sodium chloride, chemical purity.

(2) Measurement of physical and chemical Properties

1) Measuring water content, and visually observing the test article under natural light

Weighing 3g (weighing standard to 0.1mg) of sample in a weighing bottle with constant weight, placing the sample in a constant temperature drying oven, keeping the temperature at (105 +/-3) DEG C for 4h, taking out the sample, placing the sample in a dryer, cooling the sample to room temperature, and weighing the mass (weighing standard to 0.1mg) of the sample according to the following calculation formula:

in the formula: w represents water,%; m is₀Representing the weight of the weighing flask, g; m is₁Represents vial and sample mass, g; m is₂Represents the post-bake vial and sample mass, g.

And (3) test results: the fluid loss additives of examples 1-5 were all pale gray free-flowing powders with a mean moisture content index of 8.9.

2) Determination of the amount of rejects

20.0g of the sample was weighed and placed in a sieve having a pore size of 0.42mm, and the sample was quickly shaken until no sample passed, and the mass of the residue on the sieve was measured. The calculation formula is as follows:

in the formula: p represents the content of the residue on sieve,%; m is₂Represents the sample mass, g; m1 representsMass of the residue on sieve, g.

And (3) test results: the fluid loss additives of examples 1-5 had a mean value of 8.6 on the oversize with a mesh opening size of 0.42 mm.

3) Fluid loss measurement

And (3) adding 350mL of 12 parts of prepared base slurry into 5.25g of samples respectively, and stirring at a high speed for 20 min. 6 parts of the solution were sealed at room temperature for 16 hours, and one part (abbreviated as API) was used in each of examples 1 to 5 and comparative examples. Another 6 parts of the base slurry were charged into a high-temperature tank, and one part of each of examples 1 to 5 and comparative examples was placed and hot-rolled at 160 ℃ for 16 hours, followed by cooling and taking out (abbreviated as HTHP). The two sample slurries to be tested are stirred at high speed for 20min, and the filtration loss before and after high temperature (0.7mpa/30min) is measured.

The measurement was repeated by using the temperature as a variable and the above-mentioned method, and the measurement results are shown in FIG. 1. As can be seen from fig. 1: the fluid loss additive of the comparative example showed a more gradual increase in fluid loss measured by the API method and a more rapid increase in fluid loss measured by the HTHP method after a high temperature of 180 ℃; while the fluid loss additives of examples 1-5 remained relatively stable before the high temperature of 250 ℃, as measured by the API method, and as measured by the HTHP method; in addition, the fluid loss control agents of examples 1-5 were lower in overall fluid loss relative to the comparative examples.

4) Viscosity measurement

The results of statistically comparing the apparent viscosity and the plastic viscosity of the fluid loss additive after the high-temperature treatment with the temperature conditions described in 3) are shown in table 1:

TABLE 1 results of apparent viscosity and Plastic viscosity measurements

As can be seen from table 1, the fluid loss additives prepared in examples 1 to 5 have apparent viscosities and plastic viscosities substantially higher than those of the fluid loss additives in the comparative examples, with the best fluid loss additive in example 5; in addition, the increase of the apparent viscosity and the plastic viscosity of the fluid loss additive prepared in examples 1 to 5 after the high-temperature heat treatment is significantly higher than that of the fluid loss additive in the comparative example.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.