CN119371585A

CN119371585A - Preparation method, product and application of oil-responsive latex

Info

Publication number: CN119371585A
Application number: CN202411498589.2A
Authority: CN
Inventors: 郭锦棠; 王建卫; 胡苗苗
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2024-10-25
Filing date: 2024-10-25
Publication date: 2025-01-28

Abstract

The invention relates to the technical field of oilfield development drilling and cementing, in particular to a preparation method, a product and application of oil response type latex. The preparation method of the oil response type latex comprises the following steps of 1, adding an anionic emulsifier and a nonionic emulsifier into water to be dissolved to obtain an emulsifier solution, 2, mixing an acrylic monomer, styrene, a cross-linking agent and an initiator to form a monomer solution, 3, adding the monomer solution into the emulsifier solution to be mixed and uniformly dispersed into emulsion, and 4, reacting the emulsion to obtain the oil response type latex. When the oil-responsive latex of the invention breaks the cement sheath to generate oil channeling, the oil-responsive latex can quickly cause swelling, and the volume expansion of the polymer film can fill cracks, so that the cracks heal. The product can adapt to the high-temperature high-pressure and oil-gas channeling environment of an oil-gas well, and realizes effective self-healing of cracks.

Description

Preparation method, product and application of oil response type latex

Technical Field

The invention relates to the technical field of oilfield development drilling and cementing, in particular to a preparation method, a product and application of oil response type latex.

Background

Cementing is a key process in oil and gas exploration, with the aim of establishing oil and gas recovery channels with good sealing properties. The cement sheath formed in the well cementation engineering can support the wall of the well and the sleeve, prevent the sleeve from being corroded, control abnormal pore pressure and isolate fluids between stratum. The seal integrity of the cement sheath of the well is critical to the safe operation of the entire life cycle of the hydrocarbon well. Because oil well cement is inherently brittle and is extremely easily damaged, microcracks in the matrix and cementing interface are unavoidable, resulting in reduced mechanical properties and sealing capabilities of the cement sheath and even ring pressure and formation fluid passages, which can create significant potential hazards to the sealing integrity of the wellbore.

The improvement of the integrity of the well cementation cement sheath is mainly focused on improving the toughness deformation capacity of cement stones and effectively repairing the existing microcracks. The toughening means of the well cementation cement sheath mainly comprises externally doped toughening agents, and typical toughening materials comprise latex, fibers, whiskers and elastic and ductile particles. The above materials only enhance the toughness and crack resistance of cement materials to some extent, but the self-healing ability of these materials has not been reported yet. Autonomous healing is a healing technique of manual intervention, and when cracking occurs during cement service, the self-healing agent is released and solidifies cracks, mainly comprising microcapsules, shape memory alloy, mineral additives and microorganisms. However, the existing self-healing material can cause the mechanical property of the cement stone to be reduced. It is therefore desirable to develop a self-healing agent that enhances the toughness of the set cement sheath to enhance the seal integrity of the cement sheath.

Disclosure of Invention

The invention aims to provide a preparation method, a product and application of oil response type latex, which are used for solving the technical problem that the mechanical property of cement stone is reduced due to self-healing materials in the prior art. The oil response type latex has the characteristics of self-healing, quick and intelligent oil response, and capability of improving the toughness and the crack resistance of cement stones.

In order to achieve the above object, the present invention provides the following solutions:

according to one of the technical schemes, the preparation method of the oil response type latex comprises the following steps:

step 1, adding an anionic emulsifier and a nonionic emulsifier into water for dissolution to obtain an emulsifier solution;

step 2, mixing an acrylic monomer, styrene, a cross-linking agent and an initiator to form a monomer solution;

Step 3, adding the monomer solution into the emulsifier solution, mixing and uniformly dispersing to form emulsion;

And step 4, obtaining the oil response type latex after the emulsion reaction.

In the preferred embodiment of the invention, in the step 1, the anionic emulsifier is sodium dodecyl sulfate, and the nonionic emulsifier is alkylphenol ethoxylate-10.

In a preferred embodiment of the present invention, in step 1, the mass ratio of the anionic emulsifier, the nonionic emulsifier and the water is (1.2-3.5) to (80-200). In step 1, the anionic emulsifier and the nonionic emulsifier are fully dissolved in water by stirring for 20-30min.

In the invention, the dosage of the emulsifier is in the range of 1.2-3.5, and the synthesized emulsion is stable and has little bubble content. If the dosage of the emulsifier is too small, the molecules of the emulsifier are insufficient to cover the whole oil-water interface, and are loosely arranged on the interface, so that the interfacial tension cannot be the lowest, and the emulsion system is unstable. The use amount of the emulsifier is too large, and although the interfacial tension is reduced to the minimum, stable emulsion is obtained, foam is increased, the quality of the emulsion is affected, inconvenience is brought to use, and meanwhile, the production cost is increased.

In the preferred embodiment of the invention, in the step 2, the acrylic monomer is a mixture of butyl methacrylate and stearyl methacrylate, the cross-linking agent is divinylbenzene or tripropylene glycol diacrylate, and the initiator is azobisisobutyronitrile or benzoyl peroxide.

In a preferred embodiment of the invention, in the step 2, the mass ratio of the butyl methacrylate, the stearyl methacrylate, the styrene, the crosslinking agent and the initiator is (4-8.3): (6.8-16.2): (12-26.6): (0.16-0.36): (0.4-8).

In the invention, the ester chain segment mainly plays an affinity role with organic solvent molecules in a polymer three-dimensional network, but the ester monomer is a soft chain segment, and the too high content can cause the system strength to be too low and can not form a grid for effectively absorbing the organic solvent. The polystyrene chain segment is a hard segment and mainly plays a supporting role in a resin three-dimensional network, but if the content of the styrene is too high, the rigidity of the polymer molecular chain segment is strong, the chain segment is difficult to stretch, the affinity acting force with organic solvent molecules is reduced, and the oil absorption rate is reduced.

In the step 3, the ultrasonic cell grinder is used for uniform dispersion, and the dispersion time is 20-40min.

In a preferred embodiment of the invention, in step 4, the temperature of the reaction is 65-75 ℃.

In the present invention, the reason for defining the reaction temperature of 65-75 ℃ is that at this reaction temperature, the AIBN initiator decomposition efficiency is at a medium level, the degree of polymerization of the polymer is at a medium level, and good physicochemical properties are provided. When the polymerization temperature is too low, active centers generated by AIBN decomposition are few, partial unpolymerized monomers exist, the internal structure is unstable, collapse easily occurs in the oil absorption process, and the oil absorption effect is poor. Too high a temperature, too high an initiator decomposition efficiency, easy dead-end polymerization, and increased possibility of agglomeration due to collision between latex particles, and decreased stability.

In a preferred embodiment of the invention, in step 4, the reaction time is from 4.5 to 6 hours. The reaction time affects the degree of polymerization and the conversion of the polymer. The reaction time is too short, the polymerization reaction is incomplete, the monomer is not polymerized, and the energy waste is caused by too long reaction time. The invention therefore defines the reaction time as being within the above-mentioned parameters.

According to a second technical scheme of the invention, the oil response type latex prepared by the preparation method is prepared.

The third technical scheme of the invention is the application of the oil response type latex in well cementation engineering. In particular to application in oil well cement toughening and crack plugging.

According to the fourth technical scheme, the toughness and the cracking resistance of the cement material are improved by adding the oil response type latex into cement. The addition amount of the oil response type latex is 5-8% of the mass of the cement.

The invention discloses the following technical effects:

1. the preparation process is simple and easy to operate, the sources of raw materials are wide, and the preparation method is easy for large-scale engineering application.

2. The colloid particles in the oil response type latex are adsorbed and accumulated between the hydration product and pores to form a flexible uniform film, and the pore structure is thinned, so that a more uniform and compact microstructure is formed. The polymer film can absorb stress and bridge microcracks, and the toughness and the crack resistance of the cement material are improved.

3. When the oil-responsive latex of the invention breaks the cement sheath to generate oil channeling, the oil-responsive latex can quickly cause swelling, and the volume expansion of the polymer film can fill cracks, so that the cracks heal. The product can adapt to the high-temperature high-pressure and oil-gas channeling environment of an oil-gas well, and realizes effective self-healing of cracks.

4. The oil-responsive latex of the invention can enhance the toughness and crack resistance of cement materials and endow the cement materials with self-healing capability of cracks. The sealing integrity of the well cementation cement sheath is improved from two aspects of prevention and control combination.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments 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 other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is an infrared spectrum of the oil-responsive latex prepared in example 3.

Fig. 2 (a) shows the flexural strength of the pure cement and the oil-responsive latex-modified set cement prepared in example 3, and fig. 2 (b) shows the stress-strain curve of the pure cement and the oil-responsive self-repairing and toughening emulsion-modified set cement prepared in example 3.

FIG. 3 is a microstructure of a cement and oil-responsive self-healing toughened emulsion modified set-cement prepared in example 3.

Fig. 4 (a) is a statistical chart of the width of artificial cracks of the set cement, and (b) is a graph representing the self-healing capacity of the set cement modified by the oil-responsive self-repairing and toughening emulsion prepared in example 3.

Detailed Description

Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples of the present invention are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.

The technical scheme of the invention is conventional in the field, and the reagents or raw materials are purchased from commercial sources or are disclosed.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

A preparation method of the oil response type latex comprises the following steps:

Step 1, 2g of sodium dodecyl sulfate and 2g of alkylphenol ethoxylate-10 are sequentially dissolved in 160g of deionized water according to the mass to obtain an emulsifier solution.

Step 2, 32g of stearyl methacrylate, 48g of styrene, 0.32g of divinylbenzene and 0.8g of benzoyl peroxide were mixed in this order by mass to form a monomer solution.

And step3, mixing the monomer solution prepared in the step 2 with the emulsifier solution prepared in the step 1, and uniformly dispersing by using an ultrasonic cell pulverizer under the ice water bath condition to prepare stable pre-emulsified emulsion.

And 4, reacting the pre-emulsified emulsion prepared in the step 3 for 5 hours at the temperature of 70 ℃ to obtain the oil-responsive self-repairing and toughening emulsion (namely, oil-responsive latex).

Example 2

Step 2, 32g of butyl methacrylate, 48g of styrene, 0.32g of divinylbenzene and 0.8g of benzoyl peroxide were mixed in this order by mass to form a monomer solution.

Example 3

Step 2, 13g of butyl methacrylate, 26g of stearyl methacrylate, 39g of styrene, 0.32g of divinylbenzene and 0.8g of benzoyl peroxide were mixed in this order by mass to form a monomer solution.

Example 4

Step 2, 13g of butyl methacrylate, 26g of stearyl methacrylate, 39g of styrene, 0.32g of tripropylene glycol diacrylate and 0.8g of benzoyl peroxide are mixed in this order by mass to form a monomer solution.

Example 5

Step 2, 13g of butyl methacrylate, 26g of stearyl methacrylate, 39g of styrene, 0.32g of divinylbenzene and 0.8g of azobisisobutyronitrile were mixed in this order by mass to form a monomer solution.

To verify the effect of the oil-responsive monomer on the oil absorption capacity of the oil-responsive latex, the oil absorption capacities of the oil-responsive latices prepared in examples 1,2, 3, 4 and 5 were tested, and the results are shown in table 1.

TABLE 1 oil absorption capability of oil responsive latex

As can be seen from table 1, example 1, which incorporated only stearyl methacrylate monomer, had a stronger oil absorption capacity than example 2, which incorporated only butyl methacrylate, resulting in a greater oil absorption expansion volume. The reason is that the alkyl chain of the copolymer which only introduces butyl methacrylate is shorter, so that the copolymer is difficult to crosslink into a three-dimensional network structure, the effective oil absorption and storage volume are reduced, and the oil absorption effect is affected by the smaller number of ester groups serving as lipophilic groups. Meanwhile, the long-chain stearyl methacrylate has stronger affinity to oil products, and can endow the emulsion with stronger oil absorption performance. However, long alkyl chains are easy to wind together, so that the resin structure is softer, a stable structure cannot be formed, and the oil absorption capacity of the polymer is affected, so that a part of methyl methacrylate monomer is introduced into the embodiment 1, and a proper amount of short chain monomer enables the polymerized polymer to have a structure with staggered length, and the three-dimensional structure is favorable for oil absorption and oil absorption. Comparative example 3 and example 4, the crosslinker divinylbenzene is better than tripropylene glycol diacrylate in terms of oil absorption capacity. The molecular structural formula of the oil-responsive self-healing toughening emulsion produced by emulsion polymerization in example 3 is shown in FIG. 1. Peaks at 3028cm ^-1、3059cm^-1 and 3086cm ^-1 correspond to the stretching vibrations of c=h on the benzene ring, while strong peaks at 759cm ^-1 and 698cm ^-1 are the main absorption peaks of single substitution of the benzene ring (out-of-plane bending vibrations of C-H bonds in c=c-H on the carbon skeleton of the benzene ring). The c=o functional group exhibits a stretching vibration peak at 1725cm ^-1. Methyl and methylene stretching vibration peaks were observed at 2925cm ^-1 and 2853cm ^-1 due to the longer CH ₂ segments of SMA. The emulsion prepared in this example was a copolymer of butyl methacrylate, stearyl methacrylate and styrene.

BCHP in fig. 2-4 shows set cement without the oil-responsive self-repairing toughening emulsion, PHCP-5 and PHCP-8 show set cement with 5% and 8% oil-responsive self-repairing toughening emulsion, respectively.

Subsequently, in order to evaluate the toughening effect of the oil-responsive self-repairing toughening emulsion prepared by the invention on the well cementation cement sheath, the mechanical properties of the cured ductile cement paste prepared in example 3 are tested, and the preparation mode and the mechanical properties of the cement sample are tested by referring to GB/T19139-2012 oil well cement test method. The effect of varying amounts of the oil-responsive self-healing toughening emulsion prepared in example 3 on flexural strength and stress strain of the set cement is shown in fig. 2 (a) and fig. 2 (b).

As can be seen from FIG. 2 (a), the flexural strength of the cement specimen increases with the emulsion content. The flexural strength of the cement stones containing 5% and 8% of emulsion is respectively improved by 13.3% and 14.1% compared with that of the pure cement after 3 days of curing. Along with the extension of the curing time to 28 days, the flexural strength of the set cement with the addition of the oil response type self-repairing toughening emulsion accounting for 5% of the mass of the cement is improved by 25.9% compared with the strength of the pure cement, and the flexural strength of the set cement with the addition of the emulsion of 8% is improved by 29.9% compared with the pure cement. In order to further illustrate the toughening effect of the oil-responsive self-repairing toughening emulsion on the cement stone, a uniaxial test is carried out on the oil-responsive self-repairing toughening emulsion. The elastic modulus can be calculated from the uniaxial curve, so that the toughening property of the emulsion to the cement stone is more intuitively represented. As can be seen from fig. 2 (b), when the stress is small, the blank set and the oil-responsive self-repairing and toughening emulsion-modified set show positive correlation in stress strain, and when the stress is large, the blank set shows plastic deformation, whereas the emulsion-modified set shows elastic deformation. Table 2 shows the elastic modulus of the pure cement stone and the oil-responsive self-repairing and toughening emulsion modified cement stone, and as shown in Table 2, the elastic modulus of the blank cement stone is 11.1GPa, the elastic modulus of the cement stone with 5% of emulsion doping amount is 6.27GPa, and the elastic modulus of the cement stone with 8% of emulsion doping amount is 5.69GPa. Compared with pure cement stone, the cement stone elasticity of 5% of emulsion doping amount and the cement stone elasticity modulus of 8% of emulsion doping amount are respectively reduced by 43.5% and 48.7%. These results indicate that the emulsion modified set cement has better toughness before breaking.

TABLE 2 elastic modulus of pure set cement and oil responsive self-healing toughening emulsion modified set cement

The colloidal particles undergo four processes, concentration, close packing, deformation and film formation, during cement hydration and water evaporation. Finally, the colloid particles form a film on the surface of the cement hydration product. In order to further explore the toughening mechanism of the oil response self-repairing toughening emulsion prepared by the invention, SEM analysis is carried out on the emulsion modified cement stone prepared in example 3. In fig. 3 (a), it is shown that the blank cement sample contains a large number of harmful voids and microcracks, resulting in poor void structure, high porosity and low toughness. As can be seen from fig. 3 (b), after the 5% oil-responsive self-repairing toughening emulsion is added, the pores of the cement stone are reduced, and the microstructure is more uniform and compact. This is because the colloidal particles adsorb and accumulate between the hydration product and the pores, forming a flexible and uniform film. And a two-phase space network structure which is mutually penetrated with cement is formed, so that the microstructure is more uniform and compact. In fig. 3 (c), it is shown that as the emulsion amount increases (8%), the cement void defects further decrease, and the structure is denser and flatter. The formation of the polymer film and the reduction of the pore structure improve the toughness and crack resistance of the cement material.

Self-healing test was performed on pure set cement and cement samples containing the oil-responsive self-healing toughening emulsion prepared in example 3 using a self-healing cement evaluation test instrument (SHCE-2019). The test was carried out with the seal pressure and the amount of emulsion added as variables. The test method is according to the national standard GB/T19139-2012. The working principle is that the oil above the cement column is made to invade the cement column by nitrogen pressurization. If the cement sample is self-healing, liquid will not flow out of the lower outlet. As the nitrogen pressure increases, when the vent begins to vent liquid, the pressure at that time is the critical maximum pressure of the plug, also known as breakthrough pressure. Cylindrical cement samples were prepared with a diameter of 5cm and a height of 2.5 cm. Through brazilian split experiments, through cracks were created on the specimens that were similar in geometry to the naturally occurring cracks. The peripheral slits of the test specimens were firmly stuck using a two-fluid mixed hardening adhesive (acrylic glue), and all edge slits were sealed to prevent possible liquid leakage. The cement sample used for Brazilian split test has uneven cracks and uneven crack surface. The distribution statistics of the crack widths are shown in fig. 4 (a), with the crack widths being similar for all samples. Oil flow tests were performed on cement samples to verify the self-healing ability of the fractured cement, as shown in fig. 4 (b). The blank cement sample reaches a breakthrough pressure of 0.006MPa within a few minutes, and the breakthrough pressure does not change with the extension of time due to the lack of self-healing capability. And the sealing pressure of the oil-responsive self-repairing and toughening latex modified cement stone sample is increased along with the time, and the cement stone with the mixing amount of 5% and 8% of emulsion reaches the limit values of 0.076MPa and 0.122MPa respectively at 120min and 160 min. It can be seen that under oil flow conditions, the self-healing emulsion can develop a good oil response to achieve fracture plugging of the damaged cement sample.

The oil response type self-repairing and toughening emulsion has intelligent response behavior, can effectively improve the self-healing capacity of a cement matrix, and can obviously improve the toughness and crack resistance of the cement matrix. The oil response type self-repairing and toughening emulsion has a micro-crosslinked three-dimensional network structure, and the introduction of long and short chain alkyl enhances the affinity to oil, so that the polymer film realizes crack healing through oil expansion. Meanwhile, the emulsion polymer is prepared by adopting an emulsion polymerization method, and the reason is that the emulsion polymer has obvious film forming property and can endow the cement matrix with good toughness and crack resistance. The emulsion with toughness and self-repairing capability has certain significance on the long-term sealing stability of the well cementation cement sheath.

The oil response type latex prepared by the method can improve the annular deformation capacity and toughness of the well cementation cement, effectively improve the brittleness defect of the cement sheath, endow the cement sheath with crack healing capacity and promote the sealing integrity of the well cementation cement sheath.

The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.

Claims

1. A method for preparing an oil-responsive latex, characterized in that it comprises the following steps:

Step 1, adding anionic emulsifier and nonionic emulsifier into water and dissolving them to obtain an emulsifier solution;

Step 2, mixing acrylic ester monomers, styrene, a crosslinking agent and an initiator to form a monomer solution;

Step 3, adding the monomer solution into the emulsifier solution, mixing and uniformly dispersing into an emulsion;

Step 4, the emulsion is reacted to obtain an oil-responsive latex.

2. The method for preparing an oil-responsive latex according to claim 1, characterized in that, in step 1, the anionic emulsifier is sodium lauryl sulfate; and the nonionic emulsifier is alkylphenol polyoxyethylene ether-10.

3. The method for preparing an oil-responsive latex according to claim 1 is characterized in that in step 1, the mass ratio of the anionic emulsifier, the nonionic emulsifier and water is (1.2-3.5):(1.2-3.5):(80-200).

4. The method for preparing an oil-responsive latex according to claim 1 is characterized in that, in step 2, the acrylate monomer is a mixture of butyl methacrylate and octadecyl methacrylate; the cross-linking agent is divinylbenzene or tripropylene glycol diacrylate; and the initiator is azobisisobutyronitrile or benzoyl peroxide.

5. The method for preparing an oil-responsive latex according to claim 4 is characterized in that, in step 2, the mass ratio of butyl methacrylate, octadecyl methacrylate, styrene, crosslinking agent and initiator is (4-8.3): (6.8-16.2): (12-26.6): (0.16-0.36): (0.4-8).

6. The method for preparing the oil-responsive latex according to claim 1, characterized in that in step 4, the reaction temperature is 65-75°C.

7. The method for preparing the oil-responsive latex according to claim 1, characterized in that in step 4, the reaction time is 4.5-6h.

8. The oil-responsive latex prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the oil-responsive latex as claimed in claim 8 in cementing engineering.

10. A method for improving the toughness and crack resistance of cement materials, characterized in that the toughness and crack resistance of cement materials are improved by adding the oil-responsive latex described in claim 8 to cement.