A low interfacial tension high stable foam system for controlling the mobility of CO2 flooding of heavy oil

Abstract

The application discloses a low interfacial tension high-stable foam system for controlling the mobility of CO2 flooding of thick oil, which comprises 0.05-0.5% of a foaming agent, 0.01-1% of a thick oil active inducer and the rest of water in percentage by mass; the foaming agent is compounded by a non-ionic surfactant and an ionic surfactant at a mass ratio of 5:1-1:5; and the thick oil active inducer is one or more of sodium carbonate, ammonium carbonate, potassium carbonate, sodium hydroxide, sodium tert-butoxide, sodium tetraborate, sodium ethoxide, ethylenediamine, diisopropyl alcohol amine and triethylamine. The application can form high-stable foam in the CO2 channeling channel of the thick oil reservoir containing residual oil, effectively inhibit CO2 channeling and expand the CO2 sweeping efficiency; the application can reduce the interfacial tension between the foam system and the thick oil, and further improve the oil washing efficiency of the thick oil reservoir; and the application can use the thick oil active inducer to enhance the foam system to improve the recovery efficiency and reduce the system cost.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil. Background Technology

[0002] Heavy oil is an important petroleum resource, with global recoverable reserves of heavy oil (including oil sands) accounting for approximately 36% of total recoverable oil reserves, attracting significant attention from the petroleum industry. China, as the world's fourth-largest heavy oil resource country, possesses heavy oil resources accounting for over 20% of its total petroleum resources, with proven reserves of 43.5 × 10⁻⁶. 8 Heavy oil is widely distributed in oilfields such as Liaohe, Shengli, Xinjiang, Bohai, and Henan. Steam injection is currently the main technology for heavy oil development, but steam injection recovery rates are less than 20% for about 50% of heavy oil reserves, and it suffers from high energy consumption and high CO2 emissions. Therefore, under the background of green and low-carbon transformation in the energy industry, new technological approaches are urgently needed for heavy oil extraction.

[0003] In deep heavy oil reservoirs, CO2 exists in a supercritical state, exhibiting strong dissolving and diffusion capabilities in crude oil. It can impermeably displace heavy oil through mechanisms such as reducing crude oil viscosity, causing it to expand, and extracting light and medium-grade components. Furthermore, it can permanently encapsulate itself within the reservoir through mechanisms like dissolution, mineralization, and confinement, achieving a perfect balance between oil displacement and storage. However, dynamics of CO2-driven heavy oil production indicate that the significant viscosity difference between CO2 and heavy oil, coupled with the natural heterogeneity of the reservoir, makes CO2 highly susceptible to cross-flow, resulting in low macroscopic sweep efficiency.

[0004] Alternating water-gas injection is a conventional method for suppressing gas channeling. The Wilmington oilfield in the US, the Bati Raman oilfield in Turkey, and the Liaohe oilfield in China have all adopted this method in CO2 flooding of heavy oil. However, this method has weak mobility control capabilities, and the mobility ratio of the displaced heavy oil remains relatively high. Foam, a heterogeneous system formed by the dispersion of gas in a liquid, can reduce gas mobility by orders of magnitude, significantly enhancing its mobility control capabilities compared to alternating water-gas injection, and thus holds great potential for gas channeling control. Although foam has shown some effectiveness in preventing gas channeling in field applications, it suffers from inherent instability when encountering oil, especially in heavy oil reservoirs with high residual oil saturation, where foam struggles to generate sufficient seepage resistance to effectively control the mobility ratio. Furthermore, the interfacial tension between the foam system and heavy oil is typically high, leading to poor oil-water emulsification, weak oil washing ability of the foam system, and slow growth in heavy oil recovery. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a low interfacial tension, highly stable foam system for controlling the CO2 displacement of heavy oil.

[0006] The technical solution of the present invention is as follows:

[0007] A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil, comprising, by mass percentage, 0.05-0.5% foaming agent, 0.01-1% heavy oil activity inducer, and the remainder being water.

[0008] Preferably, the foaming agent is a mixture of nonionic surfactant and ionic surfactant in a mass ratio of 5:1 to 1:5.

[0009] Preferably, the nonionic surfactant is one or more of the following: dodecyl polyoxyethylene ether, polyoxyethylene sorbitan monopalmitate, phenolic resin polyoxyethylene ether, nonylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, and octyl alcohol polyoxyethylene ether.

[0010] Preferably, the ionic surfactant is one of cationic surfactants, anionic surfactants, or amphoteric surfactants.

[0011] Preferably, the cationic surfactant is hexadecyltrimethylammonium bromide and / or hexadecylpyridine bromide.

[0012] Preferably, the anionic surfactant is one or more of fatty alcohol polyoxyethylene ether sulfate, fatty alcohol polyoxyethylene ether carboxylate, sodium dodecyl sulfate, sodium dodecylbenzene cyclamate, and α-olefin sulfonate.

[0013] Preferably, the zwitterionic surfactant is one or more of lauramidopropylamine oxide, alkylphenol polyoxyethylene ether phosphate, lauryl amphoteric imidazoline, erucamide propyl betaine, oleamide propyl betaine, dodecyl hydroxypropyl sulfobetaine, and cetearyl hydroxypropyl sulfobetaine.

[0014] Preferably, the heavy oil activity inducer is one or more of sodium carbonate, ammonium carbonate, potassium carbonate, sodium hydroxide, sodium tert-butoxide, sodium tetraborate, sodium ethoxide, ethylenediamine, diisopropanolamine, and triethylamine.

[0015] The beneficial effects of this invention are:

[0016] This invention can form highly stable foam in the CO2 channel of heavy oil reservoirs containing residual oil, effectively suppressing CO2 channeling and expanding CO2 sweep efficiency; this invention can reduce the interfacial tension between the foam system and heavy oil, further improving the oil washing efficiency of heavy oil reservoirs; this invention can utilize the heavy oil activity inducer to enhance the foam system, improve the recovery capacity, and reduce system costs. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0018] This invention provides a low interfacial tension and high stability foam system for controlling the CO2 displacement of heavy oil, comprising, by mass percentage, 0.05-0.5% foaming agent, 0.01-1% heavy oil activity inducer, and the remainder being water.

[0019] In one specific embodiment, the foaming agent is a compound of nonionic surfactant and ionic surfactant in a mass ratio of 5:1 to 1:5, and the heavy oil activity inducer is one or more of sodium carbonate, ammonium carbonate, potassium carbonate, sodium hydroxide, sodium tert-butoxide, sodium tetraborate, sodium ethoxide, ethylenediamine, diisopropanolamine, and triethylamine.

[0020] In the above embodiments, the present invention can utilize the alkaline inducer to activate the active components in heavy oil and synergize them with a high HLB value foaming agent. On the one hand, it forms a stable oil-in-water emulsion, improving foam stability and enhancing the flow control capability of the foam in oily environments; on the other hand, it reduces the oil-water interfacial tension, improves the oil-washing ability of the foam system, and promotes oil-water emulsification. Furthermore, the foaming agent used in the above embodiments can form stable high-oil-content CO2 foam in both bulk and porous media. Even at an oil-water ratio as high as 1, the oil-content CO2 foam still exhibits high stability, with both the liquid half-life and foam half-life exceeding 300 minutes.

[0021] In one specific embodiment, the nonionic surfactant is one or more of the following: dodecyl polyoxyethylene ether, polyoxyethylene sorbitan monopalmitate, phenolic resin polyoxyethylene ether, nonylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, and octyl alcohol polyoxyethylene ether.

[0022] In one specific embodiment, the ionic surfactant is one of a cationic surfactant, anionic surfactant, or amphoteric surfactant.

[0023] Optionally, the cationic surfactant is hexadecyltrimethylammonium bromide and / or hexadecylpyridine bromide; the anionic surfactant is one or more of fatty alcohol polyoxyethylene ether sulfate, fatty alcohol polyoxyethylene ether carboxylate, sodium dodecyl sulfate, sodium dodecylbenzene cyclamate, and α-olefin sulfonate; and the zwitterionic surfactant is one or more of lauramide propylamine oxide, alkylphenol polyoxyethylene ether phosphate, lauryl amphoteric imidazoline, erucamide propyl betaine, oleamide propyl betaine, dodecyl hydroxypropyl sulfobetaine, and hexadecyl octadecyl hydroxypropyl sulfobetaine.

[0024] Example 1

[0025] A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil is prepared through the following steps:

[0026] (1) Take 0.1g of foaming agent (including 0.075g of nonionic surfactant dodecyl polyoxyethylene ether and 0.025g of anionic surfactant sodium dodecyl sulfate), and add 99.9g of a mineralization degree of 1.2×10 under low-speed stirring. 4 In simulated formation water at a concentration of mg / L, foaming agent solution 1 is obtained after complete dissolution.

[0027] (2) Add 0.1g of heavy oil active inducer 1 (including 0.05g of potassium carbonate and 0.05g of sodium tert-butoxide) to the foaming agent solution 1 to obtain foam system 1.

[0028] Example 2

[0029] A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil is prepared through the following steps:

[0030] (1) Take 0.3g of foaming agent (including 0.1g of nonionic surfactant phenolic resin polyoxyethylene ether, 0.1g of amphoteric surfactant alkylphenol polyoxyethylene ether phosphate, and 0.1g of laurylamidopropylamine oxide), and add 99.7g of a mineralization degree of 2.4×10 under low-speed stirring conditions. 4 In simulated formation water at a concentration of mg / L, foaming agent solution 2 is obtained after complete dissolution.

[0031] (2) Add 0.2g of heavy oil activity inducer 2 (including 0.1g of potassium carbonate and 0.1g of triethylamine) to the foaming agent solution 2 to obtain foam system 2.

[0032] Example 3

[0033] A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil is prepared through the following steps:

[0034] (1) Take 0.25g of foaming agent (including 0.1g of nonionic surfactant castor oil polyoxyethylene ether and 0.15g of amphoteric surfactant erucamide propyl betaine), and add 99.75g of a mineralization degree of 3.6×10 under low-speed stirring conditions. 4 In simulated formation water at a concentration of mg / L, foaming agent solution 3 is obtained after complete dissolution.

[0035] (2) Add 0.2g of heavy oil activity inducer 3 (including 0.1g of sodium tert-butoxide and 0.1g of triethylamine) to the foaming agent solution 3 to obtain foam system 3.

[0036] Example 4

[0037] A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil is prepared through the following steps:

[0038] (1) Take 0.3g of foaming agent (including 0.1g of nonionic surfactant octanol polyoxyethylene ether, 0.1g of amphoteric surfactant cetearylhydroxypropyl sulfobetaine, and 0.1g of lauryl amphoteric imidazoline), and add 99.7g of a mineralization degree of 4.8×10 under low-speed stirring. 4 In simulated formation water at a concentration of mg / L, foaming agent solution 4 is obtained after complete dissolution.

[0039] (2) Add 0.3g of heavy oil activity inducer 4 (including 0.1g of sodium tert-butoxide, 0.1g of sodium tetraborate, and 0.1g of triethylamine) to the foaming agent solution 4 to obtain foam system 4.

[0040] Comparative Example 1

[0041] A foam system is prepared by the following steps:

[0042] (1) Take 0.1g of foaming agent (including 0.075g of cationic surfactant cetyltrimethylammonium bromide and 0.025g of cetylpyridine bromide), and add 99.9g of a mineralization degree of 1.2×10 under low-speed stirring. 4 In simulated formation water at a concentration of mg / L, after complete dissolution, foaming agent solution 1' is obtained.

[0043] (2) Add 0.1g of heavy oil activity inducer 1 (including 0.05g of potassium carbonate and 0.05g of sodium tert-butoxide) to the foaming agent solution 1' to obtain foam system 1'.

[0044] Comparative Example 2

[0045] A foam system is prepared by the following steps:

[0046] (1) Take 0.3g of foaming agent (including 0.1g of anionic surfactant sodium dodecyl sulfate, 0.1g of amphoteric surfactant alkylphenol polyoxyethylene ether phosphate, and 0.1g of laurylamidopropylamine oxide), and add 99.7g of a mineral with a mineralization degree of 2.4×10 under low-speed stirring conditions. 4 In simulated formation water at a concentration of mg / L, after complete dissolution, foaming agent solution 2' is obtained.

[0047] (2) Add 0.2g of heavy oil active inducer 2 (including 0.1g of potassium carbonate and 0.1g of triethylamine) to the foaming agent solution 2' to obtain foam system 2'.

[0048] Comparative Example 3

[0049] A foam system is prepared by the following steps:

[0050] (1) Take 0.25g of foaming agent (including 0.1g of nonionic surfactant castor oil polyoxyethylene ether and 0.15g of phenolic resin polyoxyethylene ether), and add 99.75g of a mineralization degree of 3.6×10 under low-speed stirring. 4 In simulated formation water at a concentration of mg / L, after complete dissolution, a foaming agent solution 3' is obtained.

[0051] (2) Add 0.2g of heavy oil activity inducer 3 (including 0.1g of sodium tert-butoxide and 0.1g of triethylamine) to the foaming agent solution 3' to obtain foam system 3'.

[0052] Comparative Example 4

[0053] A foam system is prepared by the following steps:

[0054] (1) Take 0.3g of foaming agent (including 0.1g of nonionic surfactant octanol polyoxyethylene ether, 0.1g of castor oil polyoxyethylene ether, and 0.1g of phenolic resin polyoxyethylene ether), and add 99.7g of a mineralization degree of 4.8×10 under low-speed stirring. 4 In simulated formation water at a concentration of mg / L, after complete dissolution, a foaming agent solution 4' is obtained.

[0055] (2) Add 0.3g of heavy oil activity inducer 4 (including 0.1g of sodium tert-butoxide, 0.1g of sodium tetraborate, and 0.1g of triethylamine) to the foaming agent solution 4' to obtain foam system 4'.

[0056] Test Example 1: Testing the oil resistance of foam

[0057] The oil resistance of foams in Example 1 and Comparative Example 1 was tested using heavy oil with a viscosity of 261 mPa·s at 55°C. Specifically, 40 mL of foaming agent solution and heavy oil were added to a high-temperature, high-pressure foaming device at an oil-to-water ratio of 0.3. After preheating to 40°C, CO2 was introduced until the pressure reached 10 MPa. The foaming agent solution was stirred at 1200 r / min for 3 min to form oil-containing foam. The foam properties were observed and recorded, and the results are shown in Table 1.

[0058] Table 1. Properties of oil-containing foam in Example 1 and Comparative Example 1

[0059] Case name Foaming volume (mL) Liquid half-life (min) Foam half-life (min) Example 1 Foaming agent 1 108 8 46 Comparative Example 1 Foaming agent 1' 97 5 22 Example 1 Foam System 1 114 33 140 Comparative Example 1 Foam System 1' 99 8 21

[0060] As shown in Table 1, the foam produced by foaming agent 1 exhibits poor oil resistance under high oil content conditions, but it is better than the foam produced by foaming agent 1'. This indicates that the nonionic + ionic surfactant system of the present invention has better foam properties than the ionic + ionic surfactant system. The foam produced by foam system 1' still has poor oil resistance under high oil content conditions, while the foam produced by foam system 1 shows better oil resistance under high oil content conditions. This indicates that the heavy oil activity inducer 1 described in the present invention does not significantly improve the foam properties of foaming agent 1', but it can effectively improve the foam properties of foaming agent 1 under high oil content conditions and enhance its oil resistance.

[0061] The oil resistance of foams in Example 2 and Comparative Example 2 was tested using heavy oil with a viscosity of 1753 mPa·s at 55°C. Specifically, 40 mL of foaming agent solution and heavy oil were added to a high-temperature, high-pressure foaming device at an oil-to-water ratio of 0.4. After preheating to 50°C, CO2 was introduced until the pressure reached 15 MPa. The foaming agent solution was stirred at 1200 r / min for 3 min to form oil-containing foam. The foam properties were observed and recorded, and the results are shown in Table 2.

[0062] Table 2. Properties of oil-containing foam in Example 2 and Comparative Example 2

[0063] Case name Foaming volume (mL) Liquid half-life (min) Foam half-life (min) Example 2 Foaming agent 2 105 14 62 Comparative Example 2 Foaming agent 2' 102 9 29 Example 2 Foam System 2 114 60 300 Comparative Example 2 Foam System 2' 100 10 24

[0064] As shown in Table 2, the foam produced by foaming agent 2 exhibits poor oil resistance under high oil content conditions, but it is still superior to the foam produced by foaming agent 2'. This indicates that the nonionic + ionic surfactant system of this invention has better foam properties than the ionic + ionic surfactant system. The foam properties produced by foam system 2' and foaming agent solution 2' are similar, indicating that the heavy oil activity inducer 2 does not improve the foam properties of foaming agent solution 2'. Compared to the foam produced by foaming agent 2, the foam produced by foam system 2 has better oil resistance, indicating that the heavy oil activity inducer 2 can improve the foam properties of foaming agent solution 2 under high oil content conditions and enhance its oil resistance.

[0065] The oil resistance of foams in Example 3 and Comparative Example 3 was tested using heavy oil with a viscosity of 5282 mPa·s at 55°C. Specifically, 40 mL of foaming agent solution and heavy oil were added to a high-temperature, high-pressure foaming device at an oil-to-water ratio of 0.6. After preheating to 60°C, CO2 was introduced until the pressure reached 20 MPa. The foaming agent solution was stirred at 1200 r / min for 3 min to form oil-containing foam. The foam properties were observed and recorded, and the results are shown in Table 3.

[0066] Table 3. Properties of oil-containing foam in Example 3 and Comparative Example 3

[0067] Case name Foaming volume (mL) Liquid half-life (min) Foam half-life (min) Example 3 Foaming agent 3 106 18 70 Comparative Example 3 Foaming agent 3' 96 7 22 Example 3 Foam System 3 115 75 >300 Comparative Example 3 Foam System 3' 100 11 19

[0068] As shown in Table 3, the foam produced by foaming agent 3 exhibits stronger oil resistance under high oil content conditions than the foam produced by foaming agent 3', indicating that the foam properties of the nonionic + ionic surfactant system of this invention are superior to those of the nonionic + nonionic surfactant system. The foam properties produced by foam system 3' and foaming agent solution 3' are similar, indicating that the heavy oil activity inducer 3 has no effect on improving the foam properties of foaming agent solution 3'. The foam properties of foam system 3 are significantly better than those of foaming agent 3, indicating that the heavy oil activity inducer 3 can significantly improve the foam properties of foaming agent solution 3 under high oil content conditions and enhance its oil resistance.

[0069] The oil resistance of foams in Example 4 and Comparative Example 4 was tested using heavy oil with a viscosity of 7487 mPa·s at 55°C. Specifically, 40 mL of foaming agent solution and heavy oil were added to a high-temperature, high-pressure foaming device at an oil-to-water ratio of 1. After preheating to 70°C, CO2 was introduced until the pressure reached 25 MPa. The foaming agent solution was stirred at 1200 r / min for 3 min to form oil-containing foam. The foam properties were observed and recorded, and the results are shown in Table 4.

[0070] Table 4. Properties of oil-containing foam in Example 4 and Comparative Example 4

[0071] Case name Foaming volume (mL) Liquid half-life (min) Foam half-life (min) Example 4 Foaming agent 4 106 17 55 Comparative Example 4 Foaming agent 4' 101 10 21 Example 4 Foam System 4 114 >300 >300 Comparative Example 4 Foam system 4' 105 7 28

[0072] As shown in Table 4, the foam produced by foaming agent 4 exhibits stronger oil resistance under high oil content conditions than the foam produced by foaming agent 4', indicating that the foam properties of the nonionic + ionic surfactant system of this invention are superior to those of the nonionic + nonionic surfactant system. The foam properties produced by foam system 4' and foaming agent solution 4' are similar, indicating that the heavy oil activity inducer 4 has no effect on improving the foam properties of foaming agent solution 4'. The foam properties of foam system 4 are significantly better than those of foaming agent 4, indicating that the heavy oil activity inducer 4 can significantly improve the foam properties of foaming agent solution 4 under high oil content conditions and enhance its oil resistance.

[0073] Test Example 2: Testing Interface Tension

[0074] The interfacial tension between the foam system and heavy oil (viscosity 261 mPa·s at 55°C) in each embodiment of the present invention was measured using a TX500C rotating drop interfacial tensiometer. The measurement time was 1 hour, and the test results are shown in Table 5.

[0075] Table 5 Interfacial tension of each embodiment

[0076] As can be seen from Table 5, the oil-water interfacial tension of the present invention is as low as 10. -2 mN / m can improve the oil-washing ability of the foam system and promote oil-water emulsification.

[0077] Test Example 3: Testing the flow control capability under oil-containing conditions

[0078] The flow control capability of the foam system in Example 1 under oil-bearing conditions was tested at 40℃ and 10MPa. Specifically, CO2, heavy oil (viscosity of 261 mPa·s at 55℃), and foam system 1 were co-injected into core 1 with a liquid permeability of 424 mD at a total flow rate of 3 m / d, 20% foam mass, and 20% heavy oil fraction, forming oil-bearing foam. When the injection pressure reached a stable level, the inlet and outlet pressure difference of core 1 was recorded as 1.16 MPa. The apparent viscosity was calculated to be 189.44 mPa·s using Darcy's formula, demonstrating that the foam generated by foam system 1 under oil-bearing conditions has a strong flow control capability.

[0079] The flow control capability of the foam system in Example 2 under oil-bearing conditions was tested at 50℃ and 15MPa. Specifically, CO2, heavy oil (viscosity of 1753 mPa·s at 55℃), and foam system 2 were co-injected into core 2 with a liquid permeability of 422 mD at a total flow rate of 3 m / d, 40% foam mass, and 20% heavy oil fraction, forming oil-bearing foam. When the injection pressure reached a stable level, the inlet and outlet pressure difference of core 2 was recorded as 1.20 MPa. The apparent viscosity was calculated to be 195.98 mPa·s using Darcy's formula, demonstrating that the foam generated by foam system 2 under oil-bearing conditions has a strong flow control capability.

[0080] The flow control capability of the foam system in Example 3 under oil-bearing conditions was tested at 60℃ and 20MPa. Specifically, CO2, heavy oil (viscosity of 523 mPa·s at 55℃), and foam system 3 were co-injected into core 3 with a liquid permeability of 418 mD at a total flow rate of 3 m / d, 60% foam mass, and 10% heavy oil fraction, forming oil-bearing foam. When the injection pressure reached a stable level, the inlet and outlet pressure difference of core 3 was recorded as 1.30 MPa. The apparent viscosity was calculated to be 212.31 mPa·s using Darcy's formula, demonstrating that the foam generated by foam system 3 under oil-bearing conditions has a strong flow control capability.

[0081] The flow control capability of the foam system in Example 4 under oil-bearing conditions was tested at 70℃ and 25MPa. Specifically, CO2, heavy oil (viscosity of 1254 mPa·s at 55℃), and foam system 4 were co-injected into core 4 with a liquid permeability of 424 mD at a total flow rate of 3 m / d, 40% foam mass, and 10% heavy oil fraction, forming high-oil-bearing foam. When the injection pressure reached a stable level, the inlet and outlet pressure difference of core 4 was recorded as 1.33 MPa. The apparent viscosity was calculated to be 217.21 mPa·s using Darcy's formula, demonstrating that the foam generated by foam system 4 under high oil-bearing conditions has strong flow control capability.

[0082] In summary, this invention utilizes alkaline inducers to activate active components in heavy oil and synergize them with high HLB-value foaming agents to promote oil-water emulsification, improve foam stability, enhance foam mobility control in oil-bearing environments, reduce oil-water interfacial tension, and improve the oil recovery capacity of the foam system. Compared with existing technologies, this invention represents a significant advancement.

[0083] The above description is merely a representative embodiment of the present invention and is not intended to limit the present invention in any way. Any embodiment made by those skilled in the art without departing from the scope of the present invention and utilizing the disclosed technical content is an equivalent embodiment of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A low interfacial tension, high-stability foam system for controlling CO2 displacement of heavy oil, characterized in that, The product comprises, by mass percentage, 0.05-0.5% foaming agent, 0.01-1% heavy oil activity inducer, and the remainder being water; the foaming agent is a compound of nonionic surfactant and ionic surfactant in a mass ratio of 5:1 to 1:5, wherein the ionic surfactant is one of anionic surfactant and amphoteric surfactant, and the heavy oil activity inducer is one or more of sodium carbonate, ammonium carbonate, potassium carbonate, sodium hydroxide, sodium tert-butoxide, sodium tetraborate, sodium ethoxide, ethylenediamine, diisopropanolamine, and triethylamine; The nonionic surfactant is one or more of the following: dodecyl polyoxyethylene ether, phenolic resin polyoxyethylene ether, castor oil polyoxyethylene ether, and octyl alcohol polyoxyethylene ether. The anionic surfactant is sodium dodecyl sulfate; The zwitterionic surfactant is one or more of lauramidopropylamine oxide, lauramidoimidazole, erucamide propyl betaine, oleamide propyl betaine, dodecyl hydroxypropyl sulfobetaine, and hexadecyl hydroxypropyl sulfobetaine.

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