Preparation method and application of elastic latex

Abstract

The invention relates to the technical field of well cementation admixtures in petroleum and natural gas exploitation, in particular to a preparation method and application of elastic latex, and the preparation method of the elastic latex comprises the following steps: step 1, adding 100 parts by weight of water phase into 100 parts by weight of water phase; adding 12 to 30 parts of M1 monomer, 1 to 5 parts of M2 functional monomer, 1.5 to 4 parts of surfactant, 0.2 to 0.35 part of buffering agent and 0.1 to 0.2 part of chelating agent; 2, introducing nitrogen, heating the system, adding 4-6 parts of an initiator solution, and stirring; 3, 0.1-0.2 part of a buffering agent, 1-2 parts of an initiator solution and 0.05-0.1 part of a chain transfer agent are supplemented, 15-25 parts of M3 monomers are added, and a stirring reaction is conducted for 1-3 h; 4, 0.1-0.2 part of the buffering agent, 1-2 parts of the initiator solution and 0.05-0.1 part of the chain transfer agent continue to be supplemented into the system, 12-30 parts of the M1 monomer and 1-5 parts of the M2 monomer are added, and after the stirring reaction is completed, the temperature of the system is reduced to the room temperature. When the latex provided by the invention is applied to a cement paste system, the elastic modulus is reduced, and the salt tolerance is improved.

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 preparation method and application of elastic latex. Background Art

[0002] Cementing is a very important part of the oil and gas well operation process. It not only directly determines the service life of the oil and gas wells, but also has an important impact on their recovery rate. Generally speaking, after the cementing operation, the oil and gas wells still need to be treated in various ways, such as drilling, completion and workover operations, to increase the recovery rate of underground fluids. Drilling, completion and workover operations may include but are not limited to drilling, fracturing, acidizing, logging, gravel packing and perforating. The stress generated during these operations is likely to deteriorate the bonding quality between the sealed cement sheath and the outer surface of the pipe and the well wall; and cracks and gaps will be generated inside the cement sheath, or even broken. This will affect the isolation of oil, gas and water layers and endanger the safety of the wellbore.

[0003] To solve this problem, latex is often added to the cement slurry system to improve the various properties of the cement slurry and cement sheath. For example, after adding latex to the cement slurry system, fluid loss can be controlled, the elastic modulus of the cement sheath can be increased, and gas channeling and other problems can be reduced. Generally speaking, natural or synthetic rubber can be used as latex, but multivalent cations in the cement slurry system often destroy the stability of latex. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of elastic latex. The latex provided by the present invention is used in a cement slurry system to reduce the elastic modulus and improve salt resistance, and reduce bubble generation, with the elastic modulus reduced by 20%-40%.

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

[0006] In a first aspect, the present invention provides a method for preparing an elastic latex, comprising the following steps, by weight:

[0007] Step 1: Add 12-30 parts of M1 monomer, 1-5 parts of M2 functional monomer, 1.5-4 parts of surfactant, 0.2-0.35 parts of buffer, and 0.1-0.2 parts of chelating agent to 100 parts of water phase, and use mechanical stirring to disperse them evenly;

[0008] Step 2: Purge with nitrogen, heat the system to 50-80°C, add 4-6 parts of a 10% initiator solution, and stir to react for 1-2 hours;

[0009] Step 3: add 0.1-0.2 parts of buffer, 1-2 parts of 10% initiator solution by mass and 0.05-0.1 parts of chain transfer agent, add 15-25 parts of M3 monomer, and stir to react for 1-3 hours;

[0010] Step 4: Continue to add 0.1-0.2 parts of buffer, 1-2 parts of 10% initiator solution by mass and 0.05-0.1 parts of chain transfer agent into the system, add 12-30 parts of M1 monomer and 1-5 parts of M2 monomer, stir and react for 1-2 hours. After the reaction is completed, reduce the system temperature to room temperature.

[0011] Furthermore,

[0012] The M1 monomer is one of styrene, methyl methacrylate and acrylonitrile monomers and their derivatives.

[0013] Furthermore,

[0014] M2 is a functional monomer, one or more of carboxylic acid monomers with unsaturated carbon-carbon double bonds and their salts, amide monomers with unsaturated carbon-carbon double bonds and their salts, styrene sulfonic acid and its salts, vinyl pyridine, vinylamine, 2-acrylamido-2-methylpropyl sulfonic acid (AMPS) and its salts, and allyloxyhydroxysulfonic acid (AHPS) and its salts.

[0015] Furthermore,

[0016] The chain transfer agent is one or more of dodecanethiol, n-octyl-2-phenylallyl sulfide, pentyl mercaptan, and 2,4-diphenyl-4-methyl-1-pentenylmethylstyrene linear dimer.

[0017] Furthermore,

[0018] The surfactant is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium diethyl succinate.

[0019] Furthermore,

[0020] The buffer is one or more of sodium citrate, sodium bicarbonate, and trisodium phosphate.

[0021] Furthermore,

[0022] The chelating agent is one or more of disodium ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, and sodium gluconate.

[0023] Furthermore,

[0024] The initiator solution is one or more of a sodium persulfate aqueous solution, an azobisisobutyronitrile aqueous solution, and a dibenzoyl peroxide aqueous solution.

[0025] Furthermore,

[0026] The M3 monomer is one of acrylate, a derivative of acrylate, methacrylate, and a derivative of methacrylate.

[0027] In a second aspect, the present invention provides an application of latex prepared by the method for preparing elastic latex in cement slurry.

[0028] In the constructed latex cement slurry system, it is compatible with a variety of materials, and some materials can be added to further enhance the performance. These materials can be one or more of nano silicon dioxide, glass fiber, iron powder, nano magnesium oxide, nano aluminum oxide, etc.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention prepares latex by emulsion polymerization and introduces ionic monomers during the latex synthesis process, thereby increasing the salt resistance stability of the latex.

[0031] (2) The latex of the present invention does not require a defoaming agent during use, and can be used to prepare cement slurry.

[0032] (3) The latex of the present invention can not only reduce the elastic modulus of cement paste, but also increase the compressive strength of cement paste by adding reinforcing materials. The latex of the present invention can improve the stability of the cement slurry system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The thickening curve of the latex cement slurry of 3% Example 1;

[0035] Figure 2 This is the thickening curve of the 6% latex cement slurry of Example 1. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Example 1

[0040] 1000g of deionized water was placed in a three-necked flask, into which was placed 1.5g of chelating agent disodium ethylenediaminetetraacetate, 2.8g of buffer sodium bicarbonate, 18.9g of surfactant sodium diethyl succinate, 125g of styrene, and 25g of allyloxyhydroxysulfonic acid (AHPS). The system was first mechanically stirred for 30min (stirring speed 5000rpm), and nitrogen was introduced for 30min. The system was heated to 70°C. 5g of initiator sodium persulfate was dissolved in 45g of water to form an initiator solution (mass fraction 10%). 50g of initiator solution was slowly added to the system over 20min. After reacting for 1h, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 200g of 1,3-butylene glycol diacrylate and 0.8g of chain transfer agent dodecane mercaptan were added. The reaction was continued for 1.5h. Then, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 125g of styrene, 25g of allyloxyhydroxysulfonic acid (AHPS) and 0.8g of chain transfer agent dodecane mercaptan were added. The reaction was continued for 1h, and then the temperature was cooled to room temperature.

[0041] This sample was named AH-Latex.

[0042] Example 2

[0043] 1000g of deionized water was placed in a three-necked flask, into which was placed 1.5g of chelating agent disodium ethylenediaminetetraacetate, 2.8g of buffer sodium bicarbonate, 18.9g of surfactant sodium diethyl succinate, 120g of acrylonitrile, and 25g of N,N-dimethylacrylamide. The system was first mechanically stirred for 30min (stirring speed 5000rpm), and nitrogen was introduced for 30min. The system was heated to 70°C. 5g of initiator sodium persulfate was dissolved in 45g of water to form an initiator solution (mass fraction 10%). 50g of initiator solution was slowly added to the system over 20min. After reacting for 1h, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 200g of 1,3-butylene glycol diacrylate and 0.8g of chain transfer agent dodecane mercaptan were added. The reaction was continued for 1.5h. Then 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 120g of acrylonitrile, 25g of N,N-dimethylacrylamide and 0.8g of chain transfer agent dodecane mercaptan were added. The reaction was continued for 1h.

[0044] This sample was named DM-Latex.

[0045] Example 3

[0046] 1000g of deionized water was placed in a three-necked flask, into which was placed 1.5g of chelating agent disodium ethylenediaminetetraacetate, 2.8g of buffer sodium bicarbonate, 18.9g of surfactant sodium diethyl succinate, 125g of styrene, and 25g of sodium styrene sulfonate. The system was first mechanically stirred for 30min (stirring speed 5000rpm), and nitrogen was introduced for 30min. The system was heated to 70°C. 5g of initiator sodium persulfate was dissolved in 45g of water to form an initiator solution (mass fraction 10%). 50g of initiator solution was slowly added to the system over 20min. After reacting for 1h, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 200g of 1,3-butylene glycol diacrylate and 0.8g of chain transfer agent dodecyl mercaptan were added. The reaction was continued for 1.5h. Then 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added. 125g of styrene, 25g of sodium styrene sulfonate and 0.8g of chain transfer agent dodecyl mercaptan were added. The reaction was continued for 1h.

[0047] This sample was named SS-Latex.

[0048] Comparative Example 1

[0049] 1000g of deionized water was placed in a three-necked flask, into which 1.5g of chelating agent disodium ethylenediaminetetraacetate, 2.8g of buffer sodium bicarbonate, 18.9g of surfactant sodium diethyl succinate, and 150g of styrene were placed, and nitrogen was purged for 30min. The system was first mechanically stirred for 30min (stirring speed 5000rpm) and heated to 70°C. 5g of initiator sodium persulfate was dissolved in 45g of water to form an initiator solution (mass fraction 10%). 50g of initiator solution was added to the system, and after reacting for 1h, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added, 200g of 1,3-butylene glycol diacrylate and 0.8g of chain transfer agent dodecane mercaptan were added, and the reaction was continued for 1.5h. Then, 1.2g of sodium bicarbonate buffer and 10g of 10% initiator solution were added, 150g of styrene and 0.8g of chain transfer agent dodecane mercaptan were added, and the reaction was continued for 1h, and then the temperature was cooled to room temperature.

[0050] The sample was named Latex.

[0051] (1) Latex stability test:

[0052] 1) Salt resistance test:

[0053] a. Filter 100-200 g of latex using a 400 mesh screen to provide a test sample without residue.

[0054] b. Add a certain volume of latex into a beaker and place a magnet in it for magnetic stirring.

[0055] c. While the latex is being stirred at a certain speed, quickly drop a certain amount of salt solution into it.

[0056] d. After all the salt solution is added, take out the beaker and dilute the latex solution to 400mL with clean water.

[0057] e. Weigh the 125-mesh sieve and record the weight.

[0058] f. Filter 400 mL of diluted latex through a 125-mesh sieve.

[0059] g. Place the 125-mesh sieve and the retained material thereon in an oven for drying (80°C, 6 hours), and weigh the total mass to obtain the retained material mass.

[0060] h. Weigh a clean beaker, put the same volume of latex into it, dry it directly (80℃, 24h), and weigh the mass after drying to get the mass of dry latex. Compare the mass of the retentate with the mass of the dry latex to get the sedimentation rate.

[0061] The stabilities of 20 ml of 2% sodium chloride solution, calcium chloride solution and aluminum chloride solution are shown in Table 1.

[0062] Table 1

[0063] The stability of 20 mL of 2%, 5%, 10% and 20% calcium chloride solutions is shown in Table 2.

[0064] Table 2

[0065] 2) Stability test

[0066] Take 500 mL of the prepared AH-Latex, DM-Latex, SS-Latex and Latex latex, place them in measuring cylinders, seal them, let them stand for 2 months, and measure the upper, middle and lower densities, as shown in Table 3.

[0067] Table 3

[0068] (2) Cement slurry performance test

[0069] According to the relevant provisions of the National Standard of the People's Republic of China GB / T 19139-2012 "Test Methods for Oil Well Cement" and SY-T5504.5-2010 "Evaluation Methods for Oil Well Cement Admixtures - Part 5: Anti-gas Channeling Agents", the cement slurry formed by the latex prepared in Examples 1 to 3 and Comparative Example 1 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) + 2.5% fluid loss agent + latex (dosage as shown in Table 3) + 36%-40% water. By adjusting the amount of water, the cement slurry density is controlled at 1.90±0.01g / cm 3 .

[0072] The latex AH-Latex prepared in Example 1 was prepared into cement slurry, the formula was oil well cement grade G (Jiahua) + 2.5% fluid loss agent + 3% latex + 39% water, the thickening conditions were 80°C, 35MPa, and the temperature and pressure rise time was 40min. The thickening curve is shown in Figure 1 The thickening time is 155 minutes.

[0073] The latex AH-Latex prepared in Example 1 was prepared into cement slurry, the formula was oil well cement grade G (Jiahua) + 2.5% fluid loss agent + 6% latex + 36% water, the thickening conditions were 80°C, 35MPa, and the temperature and pressure rise time was 40min. The thickening curve is shown in Figure 2The thickening time is 196 minutes.

[0074] (3) Cement stone performance test

[0075] According to the relevant provisions of the National Standard of the People's Republic of China GB / T 19139-2012 "Test Methods for Oil Well Cement" and SY-T6466-2016 "Test Methods for Performance of Oil Well Cement", the performance of the cement paste formed by the latex prepared in Examples 1 to 3 and Comparative Example 1 was evaluated, and the results are shown in Table 5. The cement slurry (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 8 h 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 7 days, and its elastic modulus was measured.

[0076] Table 5

[0077] In summary, the introduction of functional molecular monomers in the latex synthesis process increases the salt resistance of liquid latex to monovalent cations, divalent cations and trivalent cations, reduces the precipitation in salt solution; and the sedimentation stability is also enhanced during long-term storage. After the latex cement slurry is formed, it is helpful for the water loss, water separation and sedimentation stability of the cement slurry; for different amounts of latex, the cement slurry thickening curve is stable. After the cement paste is formed, the latex containing functional monomers has a significant reduction in the elastic modulus of the cement paste, and the reduction value can reach 20%-40%.

[0078] 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 method for preparing an elastic latex, characterized in that: The method comprises the following steps, by weight: Step 1: Add 12-30 parts of M1 monomer, 1-5 parts of M2 functional monomer, 1.5-4 parts of surfactant, 0.2-0.35 parts of buffer, and 0.1-0.2 parts of chelating agent to 100 parts of water phase, and use mechanical stirring to disperse them evenly; Step 2: Purge with nitrogen, heat the system to 50-80°C, add 4-6 parts of a 10% initiator solution, and stir to react for 1-2 hours; Step 3: add 0.1-0.2 parts of buffer, 1-2 parts of 10% initiator solution by mass and 0.05-0.1 parts of chain transfer agent, add 15-25 parts of M3 monomer, and stir to react for 1-3 hours; Step 4: Continue to add 0.1-0.2 parts of buffer, 1-2 parts of 10% initiator solution by mass and 0.05-0.1 parts of chain transfer agent into the system, add 12-30 parts of M1 monomer and 1-5 parts of M2 monomer, stir and react for 1-2 hours. After the reaction is completed, reduce the system temperature to room temperature.

2. The method for preparing the elastic latex according to claim 1, characterized in that: The M1 monomer is one of styrene, methyl methacrylate and acrylonitrile monomers and their derivatives.

3. The method for preparing the elastic latex according to claim 1, characterized in that: M2 is a functional monomer, one or more of carboxylic acid monomers with unsaturated carbon-carbon double bonds and their salts, amide monomers with unsaturated carbon-carbon double bonds and their salts, styrene sulfonic acid and its salts, vinyl pyridine, vinylamine, 2-acrylamido-2-methylpropyl sulfonic acid and its salts, and allyloxyhydroxysulfonic acid and its salts.

4. The method for preparing the elastic latex according to claim 1, characterized in that: The chain transfer agent is one or more of dodecanethiol, n-octyl-2-phenylallyl sulfide, pentyl mercaptan, and 2,4-diphenyl-4-methyl-1-pentenylmethylstyrene linear dimer.

5. The method for preparing the elastic latex according to claim 1, characterized in that: The surfactant is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium diethyl succinate.

6. The method for preparing the elastic latex according to claim 1, characterized in that: The buffer is one or more of sodium citrate, sodium bicarbonate, and trisodium phosphate.

7. The method for preparing the elastic latex according to claim 1, characterized in that: The chelating agent is one or more of disodium ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, and sodium gluconate.

8. The method for preparing the elastic latex according to claim 1, characterized in that: The initiator solution is one or more of a sodium persulfate aqueous solution, an azobisisobutyronitrile aqueous solution, and a dibenzoyl peroxide aqueous solution.

9. The method for preparing elastic latex according to claim 1, characterized in that: The M3 monomer is one of acrylate, a derivative of acrylate, methacrylate, and a derivative of methacrylate.

10. Use of latex prepared by the method for preparing elastic latex according to any one of claims 1 to 9 in cement slurry.

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