Modified preparation method of latex powder

Abstract

The invention relates to the technical field of well cementation admixtures in petroleum and natural gas exploitation, in particular to a modified preparation method of latex powder, and the modified preparation method of the latex powder is applied to a cement paste system. Comprising the following steps: step 1, carrying out plasma treatment on latex powder; step 2, after the treatment is completed, performing molecular modification on the surface of the latex powder, when volatile functional monomers are used for modification, putting the latex powder into a drying kettle, simultaneously putting 0.5-3g of functional monomers into the drying kettle, extracting air in the drying kettle by using an air pump so as to reduce the air pressure in the drying kettle, closing an air valve, putting the drying kettle into a drying oven, and heating until the latex powder is completely dried; when the non-volatile functional monomer is used for modification, 0.5-3 g of the functional monomer is dissolved in a solvent, and then the latex powder is placed in ethyl alcohol for modification; and step 3, placing the modified sample in the air, and performing drying treatment.

Description

Technical Field

[0001] The invention relates to the technical field of cementing admixtures in oil and natural gas exploitation, and in particular to a modification preparation method of latex powder. Background Art

[0002] As the proportion of unconventional oil and gas field exploration and development increases, the geological conditions faced by oil and gas wells become more and more complex, and the drilling and completion construction procedures become more and more numerous. This will cause the originally well-bonded cement sheath to develop cracks and gaps when facing geological movements, acid fracturing and other conditions, which will weaken the sealing effect of the cement sheath on the oil, gas and water layers, or even make it fail, which has a significant impact on the wellbore life and recovery rate.

[0003] The latex cement slurry system can deal with these problems well. The elastic modulus of the cement stone formed is reduced and the toughness is increased, which effectively copes with the impact of geological changes and subsequent construction operations. The latex cement slurry system is to add latex to the conventional cement slurry, and liquid latex is commonly used. However, liquid latex has the risk of demulsification during storage and transportation, and its stability in practical applications is also limited by the application environment. Solid latex powder has advantages in storage, transportation and use, but due to the hydrophobicity of the surface, it is difficult to disperse evenly in the cement slurry system. Summary of the invention

[0004] The purpose of the present invention is to provide a modified preparation method for latex powder. The modified preparation method for latex powder is applied to a cement slurry system. The improved hydrophilicity of the latex powder provided by the present invention is significantly enhanced, the dispersibility in the cement slurry system is increased, and the elastic modulus of cement stone is effectively reduced.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A modified preparation method for latex powder comprises the following steps:

[0007] Step 1: taking latex powder and subjecting it to plasma treatment;

[0008] Step 2: After the treatment is completed, the surface of the latex powder is molecularly modified. When a volatile functional monomer is used for modification, the latex powder is placed in a drying kettle, and 0.5-3g of the functional monomer is placed inside the kettle. The air inside is extracted with an air pump to reduce the internal air pressure of the drying kettle, and the air valve is closed. The latex powder is placed in an oven for heating. When a non-volatile functional monomer is used for modification, 0.5-3g of the functional monomer is first dissolved in a solvent, and then the latex powder is placed in ethanol for modification;

[0009] Step 3: Place the modified sample in air for drying.

[0010] Furthermore,

[0011] In step 1, the latex powder is ethylene-vinyl acetate copolymer (EVA), ethylene, vinyl chloride and vinyl laurate terpolymer (E / VC / VL), acrylate and styrene copolymer rubber powder (A / S), vinyl acetate homopolymer rubber powder (PVAC) and styrene and butadiene copolymer rubber powder (SBR).

[0012] Furthermore,

[0013] The plasma equipment used in step 1 is one of an air plasma treatment apparatus and an oxygen plasma treatment apparatus.

[0014] Furthermore,

[0015] The processing powers of the plasma equipment are 30%, 50%, 70% and 100%, and the processing time is 30s, 60s, 90s, 120s and 150s.

[0016] Furthermore,

[0017] In step 2, when a non-volatile functional monomer is used for modification, the solvent is one or more of water, methanol, ethanol, acetone, ethyl acetate, and the like.

[0018] Furthermore,

[0019] The functional monomers in step 2 are acrylic acid, methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate, 3-amino-2-(methacrylic) acid and styrene sulfonic acid.

[0020] Furthermore,

[0021] In step 2, when a volatile functional monomer is used for modification, the air inside is pumped out with an air pump until the internal pressure is 0.01 MPa.

[0022] Furthermore,

[0023] In step 2, when a volatile functional monomer is used for modification, the drying kettle is placed in an oven and heated to 40-55°C.

[0024] Furthermore,

[0025] In step 2, when a volatile functional monomer is used for modification, the drying kettle is placed in an oven and heated to 40-55° C. for 6-12 hours.

[0026] Furthermore,

[0027] When non-volatile functional monomers are used for modification, the latex powder is placed in ethanol for modification for 4-16 hours.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention utilizes simple plasma to perform surface modification to improve the hydrophilicity of latex powder.

[0030] (2) The dispersibility of the latex of the present invention in cement slurry is increased, the latex and cement paste are more closely combined, and the bonding strength is increased. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0032] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0033] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0034] Example 1

[0035] 100 g of styrene-butadiene copolymer (SBR) latex powder was taken and treated with an air plasma treatment apparatus at 100% power for 120 s.

[0036] The treated latex powder was placed in a drying kettle, and 2.5 g of methacrylic acid solution was added therein, and the internal pressure was reduced to 0.01 MPa using a vacuum pump.

[0037] Place the drying kettle in an oven, heat to 45°C, and leave for 12 hours.

[0038] The drying kettle was taken out, cooled and dried to obtain a sample, which was named SBR-AA.

[0039] Example 2

[0040] 100 g of styrene-butadiene copolymer (SBR) latex powder was taken and treated with an air plasma treatment apparatus at 100% power for 120 s.

[0041] 2 g of hydroxyethyl methacrylate was dissolved in 200 g of ethanol, latex powder was dispersed into the solution and reacted for 5 h.

[0042] After completion, the latex powder was filtered and dried to obtain a sample named SBR-HEMA.

[0043] Example 3

[0044] Take 100 g of acrylate-styrene copolymer rubber powder (A / S) latex powder and treat it with an air plasma treatment instrument at 100% power for 120 seconds.

[0045] The treated latex powder was placed in a drying kettle, and 2.5 g of methacrylic acid solution was added therein, and the internal pressure was reduced to 0.01 MPa using a vacuum pump.

[0046] Place the drying kettle in an oven, heat to 45°C, and leave for 12 hours.

[0047] The drying kettle was taken out, cooled and dried to obtain a sample, which was named A / S-AA.

[0048] Example 4

[0049] Take 100 g of acrylate-styrene copolymer rubber powder (A / S) latex powder and treat it with an air plasma treatment instrument at 100% power for 120 seconds.

[0050] 2 g of methyl methacrylate was dissolved in 200 g of ethanol, latex powder was dispersed into the solution and reacted for 5 h.

[0051] After completion, the latex powder was filtered and dried to obtain a sample named A / S-HEMA

[0052] Comparative Example 1

[0053] 100 g of styrene-butadiene copolymer (SBR) latex powder was treated with an air plasma treatment apparatus at 30%, 50%, 70% and 100% power for 30 s, 60 s, 90 s, 120 s and 150 s.

[0054] Comparative Example 2

[0055] Take 100 g of acrylate-styrene copolymer rubber powder (A / S) latex powder and treat it with an air plasma treatment instrument at 100% power for 120 seconds.

[0056] (1) Latex hydrophilic stability test:

[0057] 1) Hydrophilicity test:

[0058] a. Take a glass slide and stick a piece of double-sided tape (about 0.5*1cm in size) in the center.

[0059] b. sticking the modified latex powder and the comparative latex powder onto double-sided adhesive tapes respectively and compacting them;

[0060] c. Use a static contact angle tester (SCA-20) to test the contact angle, and the amount of water drop is 5 μl;

[0061] d. Calculate and record the contact angle value.

[0062] The contact angle values ​​of styrene-butadiene copolymer after different powers and treatment times are shown in Table 1.

[0063] Table 1

[0064] The original contact angles of various types of latex powders, the contact angle values ​​after being treated with an air plasma treatment instrument at 100% power for 120 seconds, and the contact angle values ​​after standing for 1 day and 7 days are shown in Table 2.

[0065] Table 2

[0066] The contact angles of the samples in each embodiment are shown in Table 3.

[0067] Table 3

[0068] (2) Cement slurry performance test

[0069] According to the relevant provisions of GB / T 19139-2012 "Test Methods for Oil Well Cement" and SY-T5504.5-2010 "Evaluation Methods for Oil Well Cement Admixtures - Part V: Anti-gas Channeling Agents" of the National Standards of the People's Republic of China, the latex powders prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were treated for 7 days and then added to cement slurry. The performance was evaluated at 80°C. The results are shown in Table 4.

[0070] Table 4

[0071] The formula is oil well cement grade G (Jiahua) + 1.5% fluid loss agent + latex powder (dosage as shown in Table 4) + 44% water. The water loss is measured at 80°C. The sedimentation density difference is measured at 80°C. The thickening conditions are 80°C, 40MPa, and the temperature and pressure rise time is 40min.

[0072] (3) Cement stone performance test

[0073] According to the relevant provisions of the National Standard of the People's Republic of China GB / T 19139-2012 "Test Method for Oil Well Cement" and SY-T6466-2016 "Test Method for Performance of Oil Well Cement Stone", the latex powders of Examples 1 to 4 and Comparative Examples 1 and 2 were treated for 7 days and then added to cement slurry to evaluate the performance of the cement stone formed. The results are shown in Table 5. The cement slurry containing the latex powder of the present invention (density 1.90 g / cm 3 ) was placed in a strength module (5.08 cm*5.08 cm*5.08 cm) and cured at a test temperature of 80°C for 1 day, 7 days and 28 days to measure its strength; a cement slurry (density 1.90 g / cm 3 ) was placed in an elastic modulus module (3cm*3cm*12cm) and cured at 80°C for 3 days, and its elastic modulus was measured.

[0074] Table 5

[0075] From the above results, it can be seen that the latex powder treated by the present invention has enhanced wettability and wetting stability to water, which is beneficial to the dispersion of latex powder in cement slurry. The treated latex powder has little effect on the cement slurry. Under appropriate addition, the strength of cement stone increases and the elastic modulus decreases.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified preparation method for latex powder, characterized in that: The following steps are involved: Step 1: taking latex powder and subjecting it to plasma treatment; Step 2: After the treatment is completed, the surface of the latex powder is molecularly modified. When a volatile functional monomer is used for modification, the latex powder is placed in a drying kettle, and 0.5-3g of the functional monomer is placed inside the kettle. The air inside is extracted with an air pump to reduce the internal air pressure of the drying kettle, and the air valve is closed. The latex powder is placed in an oven for heating. When a non-volatile functional monomer is used for modification, 0.5-3g of the functional monomer is first dissolved in a solvent, and then the latex powder is placed in ethanol for modification; Step 3: Place the modified sample in air for drying.

2. The modified preparation method of latex powder according to claim 1, characterized in that: In step 1, the latex powder is ethylene-vinyl acetate copolymer, ethylene, vinyl chloride and vinyl laurate terpolymer, acrylate and styrene copolymer rubber powder, vinyl acetate homopolymer rubber powder and styrene and butadiene copolymer rubber powder.

3. The modified preparation method of latex powder according to claim 1, characterized in that, The plasma equipment used in step 1 is one of an air plasma treatment apparatus and an oxygen plasma treatment apparatus.

4. The modified preparation method of latex powder according to claim 3, characterized in that: The processing powers of the plasma equipment are 30%, 50%, 70% and 100%, and the processing time is 30s, 60s, 90s, 120s and 150s.

5. The modified preparation method of latex powder according to claim 1, characterized in that: In step 2, when a non-volatile functional monomer is used for modification, the solvent is one or more of water, methanol, ethanol, acetone, ethyl acetate, and the like.

6. The modified preparation method of latex powder according to claim 1, characterized in that: The functional monomers in step 2 are acrylic acid, methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate, 3-amino-2-(methacrylic) acid and styrene sulfonic acid.

7. The modified preparation method of latex powder according to claim 1, characterized in that: In step 2, when a volatile functional monomer is used for modification, the air inside is pumped out with an air pump until the internal pressure is 0.01 MPa.

8. The modified preparation method of latex powder according to claim 1, characterized in that: In step 2, when a volatile functional monomer is used for modification, the drying kettle is placed in an oven and heated to 40-55°C.

9. The modified preparation method of latex powder according to claim 1, characterized in that: In step 2, when a volatile functional monomer is used for modification, the drying kettle is placed in an oven and heated to 40-55° C. for 6-12 hours.

10. The modified preparation method of latex powder according to claim 1, characterized in that: When non-volatile functional monomers are used for modification, the latex powder is placed in ethanol for modification for 4-16 hours.

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