A carbonized polymer molecular cluster stabilized foam system and its preparation method and application

Abstract

The present invention relates to a carbonized polymer molecular cluster-stabilized foam system, a preparation method, and applications thereof. The carbonized polymer molecular clusters are prepared by dispersing citric acid, taurine, and hexylamine in an alcohol solvent and subjecting them to a hydrothermal reaction. The carbonized polymer molecular cluster-stabilized foam system comprises the following components, measured by weight: 0.03 to 0.1 parts of carbonized polymer molecular clusters, 0.5 to 0.8 parts of an amphoteric surfactant, and 50 to 100 parts of water. The stable foam system provided by the present invention comprises carbonized polymer molecular clusters, which have excellent salt tolerance. The foam system not only improves foam stability and reduces the risk of formation damage, but also effectively enhances the environmental friendliness of the system by optimizing the selection of raw materials.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and particularly relates to a carbonized polymer molecular cluster stabilized foam system, a preparation method and an application thereof. Background Art

[0002] Foam fluids are currently widely used in oil and gas field development, with a history of nearly 60 years both domestically and internationally. Foam has achieved considerable success in many aspects of oil and gas field development, including oil flooding, water drainage and gas recovery in water-bearing gas wells, sand flushing, drilling, profile control, water plugging, acidizing, cementing, and fracturing. However, as most oil fields enter the middle and late stages of development and drilling depths continue to increase, the presence of deep, highly salinized formation water significantly reduces the foaming volume of the foaming agent and shortens the foam half-life. Sodium and calcium ions in the formation neutralize the system's charge, reducing the adsorbed charge concentration of the foam film and weakening the repulsive forces between the two sides. This, in turn, disrupts the double-electron structure, thins the film, accelerates drainage, and significantly reduces foam stability. Anionic surfactants, in particular, precipitate when they encounter inorganic salt ions. The salt ions in the formation react chemically with the foaming agent molecules to form insoluble or sparingly soluble salts, which disrupt the foaming agent's molecular structure, significantly reducing its activity or even inactivating it, thus affecting the performance of the foam system.

[0003] There are two main approaches to improving the stability of foam systems in high-salinity environments. One involves screening and compounding foaming surfactants to leverage the synergistic effects of different surfactants to enhance the salt tolerance of the foam system, or by grafting and modifying existing surfactants to introduce salt-tolerant groups before compounding. The other approach is to improve foam performance in high-salinity environments by adding foam stabilizers. Polymers, due to their long-chain or branched molecular structures, significantly increase the viscosity of the liquid phase in the foam system when dissolved in water, thereby reducing the drainage rate of the liquid film, preventing liquid loss within the film, and reducing the permeability of the liquid film, preventing gas diffusion within the foam. Therefore, they are often used as foam stabilizers. However, while the addition of organic polymers or biomacromolecules increases solution viscosity, it also reduces foam generation capacity and hinders injection into formations due to excessive viscosity. Furthermore, polymers are prone to degradation in high-salinity reservoirs, significantly reducing their foam stabilization effect, and residual polymers may contaminate the formation. Another commonly used foam stabilizer is solid particles, which help the foam system form a rigid liquid film structure, improving foam stability and, consequently, the salt tolerance of the foam system. Patent CN201210223060 discloses a composite foam system with added nanoparticles for oil and gas fields and its preparation method. The system exhibits certain salt resistance at a salinity of 25,000 mg / L, but the large amount of SiO2 particles used limits its scope of application. In addition, the particle size of conventional nanoparticles is generally above 10 nm, and adsorption and retention on the pore throat surface of the reservoir will damage the oil and gas layer to a certain extent. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide a carbonized polymer molecular cluster stabilized foam system and its preparation method and application, and solve the technical problems of poor stability and salt resistance of the foam system in the prior art.

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

[0006] In a first aspect, the present invention provides a carbonized polymer molecular cluster prepared by dispersing citric acid, taurine and hexylamine in an alcohol solvent and subjecting them to a hydrothermal reaction.

[0007] In a second aspect, the present invention provides a carbonized polymer molecular cluster stabilized foam system, which comprises the following components, calculated by mass: 0.03 to 0.1 parts of carbonized polymer molecular clusters, 0.5 to 0.8 parts of amphoteric surfactants, and 50 to 100 parts of water.

[0008] In a third aspect, the present invention provides a method for preparing a carbonized polymer molecular cluster stabilized foam system, comprising the following steps: S1, adding the carbonized polymer molecular clusters to water and dispersing them evenly to obtain a carbonized polymer molecular cluster dispersion; S2, adding an amphoteric surfactant to the carbonized polymer molecular cluster dispersion and dispersing them evenly to obtain a compound foam system solution; S3, stirring and foaming the compound foam system solution to obtain a carbonized polymer molecular cluster stabilized foam system.

[0009] In a fourth aspect, the present invention provides an application of a carbonized polymer molecular cluster stabilized foam system as a foaming agent in oil and gas field development.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] The foam system provided by the present invention comprises carbonized polymer molecular clusters, which exhibit excellent salt tolerance and are derived from environmentally friendly raw materials, meeting the requirements of green chemistry. This foam system not only improves foam stability and reduces the risk of formation damage, but also effectively enhances the system's environmental friendliness by optimizing the selection of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the carbonized polymer molecular cluster in the present invention.

[0013] Figure 2 This is a physical diagram of the change of the carbonized polymer molecular cluster stabilized foam system over time in the present invention (200 mL solution, high-speed stirring at 4000 rpm for 3 minutes). DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0015] The foam system in the prior art faces stability challenges in high-salt reservoir environments, especially for deep reservoir conditions with a salinity of more than 200,000 mg / L. Traditional foam systems have problems such as poor stability and salt tolerance. In response to the above problems, the present invention is committed to developing a new foam system that not only has excellent foaming ability and foam stability, but also its raw material source is environmentally friendly and conforms to the principles of green chemistry. It is an ultra-stable carbonized polymer molecular cluster foam system suitable for high-salt formations, which can solve the problems of insufficient salt tolerance of existing foam systems in high-salt environments, easy foam breakage, and possible residual damage to the formation. By applying the foam system of the present invention, it is expected to significantly improve the extraction efficiency of deep oil and gas fields and effectively protect the reservoir, thereby having a far-reaching impact on the sustainable development of oil and gas fields.

[0016] In a first aspect, the present invention provides a carbonized polymer molecular cluster prepared by dispersing citric acid, taurine and hexylamine in an alcohol solvent and subjecting them to a hydrothermal reaction.

[0017] This invention uses hexylamine as a raw material, reacting it with citric acid and taurine to introduce amino and sulfonic acid groups. The carbonized polymer molecular clusters have a functional group density of 70-85%. The carbonized polymer molecular clusters have a particle size distribution of 3-5 nm and are nearly spherical, with a carbonized core inside and functional groups such as amino, sulfonic acid, and hydroxyl groups distributed on the surface. The carbonized polymer molecular clusters provided by this invention are small in size and less detrimental to reservoir pore throat structure than conventional granular plugging agents.

[0018] More preferably, the mass ratio of citric acid to taurine is (0.1-10):1; more preferably, the mass ratio is 1:1.

[0019] More preferably, the ratio of the mass of hexylamine to the total mass of citric acid and taurine is (2-6):1; more preferably 1:1.

[0020] More preferably, in the hydrothermal reaction, the reaction temperature is 140-180° C., and the reaction time is 8-12 hours.

[0021] More preferably, after the hydrothermal reaction is completed, the carbonized polymer molecular clusters are obtained by post-treatment; the post-treatment is to remove the solvent by rotary evaporation at 40-60°C.

[0022] In a second aspect, the present invention provides a carbonized polymer molecular cluster stabilized foam system, which comprises the following components, calculated by mass: 0.03 to 0.1 parts of carbonized polymer molecular clusters, 0.5 to 0.8 parts of amphoteric surfactants, and 50 to 100 parts of water.

[0023] Specifically, the amount of carbonized polymer molecular clusters can be selected from 0.03 parts, 0.04 parts, 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.1 parts or any value between 0.03 and 0.1 parts; the amount of amphoteric surfactant can be selected from 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts, 0.8 parts or any value between 0.5 and 0.8 parts.

[0024] Preferably, the following components are included, calculated by mass: 0.05 parts of carbonized polymer molecular clusters, 0.8 parts of amphoteric surfactants, and 100 parts of water.

[0025] Preferably, the amphoteric surfactant includes at least one of cocamidopropyl betaine, lauramidopropyl hydroxysulfonate, lauramidopropyl betaine, and cocamidopropyl hydroxysulfonate.

[0026] Preferably, the water is deionized or mineralized water.

[0027] More preferably, the mineralization of the mineralized water is 10,000 to 250,000 mg / L.

[0028] In a third aspect, the present invention provides a method for preparing a carbonized polymer molecular cluster stabilized foam system, comprising the following steps:

[0029] S1, adding carbonized polymer molecular clusters into water and dispersing them evenly to obtain a carbonized polymer molecular cluster dispersion;

[0030] S2, adding an amphoteric surfactant to the carbonized polymer molecular cluster dispersion to uniformly disperse the dispersion to obtain a composite foam system solution;

[0031] S3, stirring and foaming the compound foam system solution to obtain a carbonized polymer molecular cluster-stabilized foam system.

[0032] Preferably, in step S1 and step S2, the dispersion method is room temperature ultrasonic dispersion, the ultrasonic power is 100-200 W, and the ultrasonic time is 5-10 min.

[0033] Preferably, in step S3, the stirring and bubbling is performed by a Waring Blender method, wherein the stirring speed is 4000-8000 rpm, the stirring time is 3 minutes, and the gas source includes one of air, nitrogen, carbon dioxide or natural gas.

[0034] In a fourth aspect, the present invention provides an application of a carbonized polymer molecular cluster stabilized foam system as a foaming agent in oil and gas field development.

[0035] Preferably, the oil and gas field is a high-salinity oil reservoir, with a high salinity range of 10,000 to 250,000 mg / L.

[0036] The main mechanism of action and advantages of the present invention:

[0037] (1) The present invention uses hexylamine as a raw material to react with citric acid and taurine to produce a carbonized polymer molecular cluster. The carbonized polymer molecular cluster has amino groups, sulfonic acid groups, and hydroxyl groups on its surface. By controlling the ratio of hexylamine to citric acid and taurine, the ratio of hydrophilic and lipophilic groups in the carbonized polymer molecular cluster can be controlled, thereby achieving regulation of the foam stabilization performance of the synthesized carbonized polymer molecular cluster. At the same time, the introduction of sulfonic acid groups improves the salt tolerance of the carbonized polymer molecular cluster. The unique structure of the molecular cluster can also improve the stability of the subsequent foam system.

[0038] (2) The present invention provides a solid, liquid and gas three-phase foam system, wherein the solid phase is a carbonized polymer molecular cluster having an amino group, a sulfonic acid group and a hydroxyl group, and the liquid phase comprises an amphoteric surfactant solution; and the carbonized polymer molecular cluster and the amphoteric surfactant and water form an ultra-stable foam system solution, which is stirred and foamed to form a three-phase foam system. The ultra-stable carbonized polymer molecular cluster foam system is suitable for high-mineralization formations and can overcome the problems of poor stability and salt resistance existing in traditional foam systems.

[0039] (3) The foam system of the present invention has good performance of each component material and is added in a moderate proportion. The liquid separation half-life of the foam system prepared by the component materials can reach more than 10 hours, and it still has good performance in 210,000 mg / L brine. It can be used as a foaming agent in the increasingly demanding oil and gas field development process in the fields of oil displacement, water-containing gas well drainage and gas production, sand flushing, drilling, profile control, water plugging, acidizing, cementing and fracturing.

[0040] The present invention is further described in detail below through specific examples and comparative examples.

[0041] Example 1 (Carbonized polymer molecular clusters)

[0042] A carbonized polymer molecular cluster, the preparation steps are as follows:

[0043] (1) Weigh 2.5 g of citric acid, 2.5 g of taurine, and 5 g of hexylamine to form a mixture, and add the mixture to 50 mL of ethanol;

[0044] (2) After uniform dispersion, pour into a 100 mL hydrothermal reactor and react at 140-180 °C for 10 hours;

[0045] (3) After the reaction is completed, the solvent is removed by rotary evaporation at 50° C. to obtain the carbonized polymer molecular clusters.

[0046] like Figure 1 As shown, the carbonized polymer molecular clusters produced by the present invention, which react hexylamine with citric acid and taurine, carry amino groups, sulfonic acid groups, and hydroxyl groups on their surfaces. These clusters also possess a large specific surface area and surface structure, resulting in strong adsorption of amphoteric surfactants. After compounding, these clusters facilitate the denser arrangement of surfactant molecules in the adsorption layer through hydrogen bonding or dipole moment interactions, thereby increasing the viscosity and elasticity of the adsorption layer, enhancing the stability of the adsorption film, and improving the foaming and foam stabilization properties of the surfactant.

[0047] Example 2 (Carbonized Polymer Molecular Cluster Stabilized Foam System)

[0048] A carbonized polymer molecular cluster stabilized foam system, the preparation steps of which are as follows:

[0049] S1: 0.1 g of carbonized polymer molecular clusters (prepared in Example 1) was added to 200 g of simulated saline with a salinity of 210,000 mg / L, and the beaker was placed in an ultrasonicator (power 150 W) for uniform dispersion to obtain a light yellow carbonized polymer molecular cluster dispersion;

[0050] S2: adding 1.6 g of a zwitterionic surfactant to the carbonized polymer molecular cluster dispersion obtained in S1, followed by ultrasonic dispersion to obtain a composite foam system solution;

[0051] S3: 100 mL of the compound foam system solution prepared in S2 was poured into a high stirring cup and stirred at 8000 rpm for 3 minutes using a Waring Blender method to obtain a carbonized polymer molecular cluster stabilized foam system.

[0052] After stirring, quickly pour the foam into a 500 mL graduated cylinder and record the foam volume and liquid separation half-life.

[0053] Example 3 (Investigation of the Effect of Carbonized Polymer Molecular Clusters on Foam System Performance)

[0054] To verify the effect of different concentrations of carbonized polymer clusters and surfactant ratios on the foam system, a carbonized polymer cluster-stabilized foam system was prepared according to the mass ratio and method of Example 2 above, with the only difference being that the carbonized polymer clusters were used in amounts of 0 wt%, 0.03 wt%, and 0.1 wt% relative to water in the carbonized polymer cluster foam system, respectively, designated as the control group, test group A, and test group C. Example 2 was designated as test group B (the carbonized polymer clusters were used in an amount of 0.05 wt% relative to water). The foam volume and liquid separation half-life of the carbonized polymer cluster-stabilized foam system at different carbonized polymer cluster dosages are shown in Table 1.

[0055] Table 1 Effect of carbonized polymer molecular clusters on foam system properties

[0056]

[0057] As shown in Table 1, under a high mineralization environment of 210,000 mg / L, the liquid precipitation half-life of the foam produced by a simple amphoteric surfactant (control group) is only 11 minutes. However, after adding a trace amount of carbonized polymer molecular clusters to test groups A and C, the stability of the foam is greatly improved. When the carbonized polymer molecular clusters are used at a dosage of 0.03%, the liquid precipitation half-life of the foam reaches 460 minutes; when the dosage exceeds 0.05%, the liquid precipitation half-life increases slowly. Taking all factors into consideration, the preferred dosage of the carbonized polymer molecular clusters of the present invention is 0.05%.

[0058] Example 4 (Investigation of the Effect of Mineralization on the Stability of Foam Systems by Carbonized Polymer Molecular Clusters)

[0059] To verify the effect of varying salinity on foam systems, foam systems were prepared according to the mass ratios and methods described in Example 2, with the only difference being that the simulated formation water salinity was 25,000 mg / L and 250,000 mg / L, respectively designated as Test Groups D and E. The foam volumes and liquid separation half-lives of the carbonized polymer cluster-stabilized foam systems at different salinities are shown in Table 2.

[0060] Table 2 Effect of mineralization on the stability of foam system by carbonized polymer molecular clusters

[0061]

[0062] As shown in Table 2, the foam system's foam volume decreases slightly with increasing salinity, but its liquid extraction half-life significantly increases. Even at a high salinity of 250,000 mg / L, the foam system exhibits a large foam volume, a large liquid carrying capacity, and a liquid extraction half-life exceeding 10 hours. This indicates that the carbonized polymer cluster-stabilized foam system provided by the present invention has excellent salt tolerance, sufficient to withstand salinities of 210,000 mg / L or even higher. Furthermore, the higher the salinity, the better the stability of the foam system provided by the present invention, making it suitable for oil and gas field development under the demanding conditions of high salinity.

[0063] Example 5

[0064] The only difference from Example 2 is that the rotation speed in the Waring Blender method is adjusted to 4000 rpm, 200 mL of the foam system solution is prepared, and the other steps and conditions are the same as Example 2.

[0065] The obtained carbonized polymer molecular cluster stable foam was poured into a 500mL graduated cylinder, and the actual figure of its change over time is shown in the figure below. Figure 2 As shown, it can be seen that its elution half-life reaches 12h.

[0066] Comparative Example 1

[0067] The only difference from Example 2 is that the amphoteric surfactant is replaced by the anionic surfactant sodium α-olefin sulfonate (AOS), and the other steps and conditions are the same as those in Example 2.

[0068] The prepared foam system solution was poured into a 500 mL graduated cylinder. The foam volume was 325 mL, but the precipitation half-life was only 20 min.

[0069] In summary, the present invention discloses a carbonized polymer molecular cluster, a stable foam system, a preparation method, and an application thereof. The foam system comprises a gas phase, a liquid phase, and a solid phase. The liquid phase is a zwitterionic surfactant solution, and the solid phase is a carbonized polymer molecular cluster. The carbonized polymer molecular cluster has functional groups such as amino groups, sulfonic acid groups, and hydroxyl groups to achieve salt tolerance of the foam system. The carbonized polymer molecular cluster and the zwitterionic surfactant can synergistically enhance each other and adsorb on the gas-liquid interface of the foam, significantly improving the structural strength of the foam liquid film, effectively slowing the flow of liquid in the liquid film, reducing the drainage effect of the liquid film, thereby weakening the rupture of the liquid film, and achieving ultra-stability of the foam in highly saline salt water. The composite foam system of the present invention has a 21×10 4 Under conditions of high salinity of 100 mg / L, the foaming volume can still reach more than 3 times the original liquid volume, and the liquid precipitation half-life reaches more than 10 hours, which is enough to meet the requirements for the stability of the foam system during the development of oil and gas fields in harsh environments with high salinity.

[0070] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A carbonized polymer molecular cluster, characterized in that: The carbonized polymer molecular cluster is prepared by dispersing citric acid, taurine and hexylamine in an alcohol solvent and performing a hydrothermal reaction.

2. The carbonized polymer molecular cluster according to claim 1, characterized in that The mass ratio of the citric acid to the taurine is (0.1-10):1; the mass ratio of the hexylamine to the total mass of the citric acid and the taurine is (2-6):

1.

3. The carbonized polymer molecular cluster according to claim 1, characterized in that In the hydrothermal reaction, the reaction temperature is 140-180° C., and the reaction time is 8-12 hours.

4. A carbonized polymer molecular cluster stabilized foam system, characterized in that: The invention comprises the following components in parts by mass: 0.03 to 0.1 parts of the carbonized polymer molecular cluster according to any one of claims 1 to 3, 0.5 to 0.8 parts of an amphoteric surfactant, and 50 to 100 parts of water.

5. The carbonized polymer molecular cluster stabilized foam system according to claim 4, characterized in that: The amphoteric surfactant includes at least one of cocamidopropyl betaine, lauramidopropyl hydroxysulfonyl betaine, lauramidopropyl betaine, and cocamidopropyl hydroxysulfonyl betaine.

6. The carbonized polymer molecular cluster stabilized foam system according to claim 4, characterized in that: The water is deionized or mineralized water with a mineralization degree of 10,000 to 250,000 mg / L.

7. The method for preparing a carbonized polymer molecular cluster stabilized foam system according to claim 4, wherein: The following steps are involved: S1, adding carbonized polymer molecular clusters into water and dispersing them evenly to obtain a carbonized polymer molecular cluster dispersion; S2, adding an amphoteric surfactant to the carbonized polymer molecular cluster dispersion to uniformly disperse the dispersion to obtain a composite foam system solution; S3, stirring and foaming the compound foam system solution to obtain a carbonized polymer molecular cluster-stabilized foam system.

8. The method for preparing a carbonized polymer molecular cluster stabilized foam system according to claim 7, characterized in that: In step S1 and step S2, the dispersion method is room temperature ultrasonic dispersion, the ultrasonic power is 100-200 W, and the ultrasonic time is 5-10 minutes.

9. The method for preparing a carbonized polymer molecular cluster stabilized foam system according to claim 7, wherein: In step S3, the stirring and foaming is performed by a Waring Blender method, wherein the stirring speed is 4000-8000 rpm, the stirring time is 3 minutes, and the gas source includes one of air, nitrogen, carbon dioxide or natural gas.

10. Use of the carbonized polymer molecular cluster stabilized foam system according to claim 4 as a foaming agent in oil and gas field development.

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