Self-generating carbon dioxide microbubble oil-displacing agent and preparation method and application thereof

Abstract

The invention relates to a self-generating carbon dioxide microbubble oil-displacing agent and a preparation method and application thereof, in particular to the technical field of oilfield development, and the self-generating carbon dioxide microbubble oil-displacing agent is prepared from microemulsion, water liquid and foam liquid according to the volume ratio of (0.1-1): (0.1-1): (0.1-1); the microemulsion comprises a first gas agent, a surfactant, an organic solvent and water; the water liquid comprises a second gas agent and water; the foam liquid comprises a foaming agent, a foam stabilizer and water. According to the self-generating carbon dioxide microbubble oil-displacing agent provided by the invention, a good oil-displacing effect can be realized by utilizing a synergistic effect among the components in the oil-displacing agent, so that the oil-displacing rate is remarkably improved; meanwhile, in the oil displacement process, the sub-agent in the oil displacement agent is injected in the form of microemulsion, and due to the controllability of the dosage of the traditional Chinese medicine in the microemulsion, a trace amount of carbon dioxide can be generated to form microbubbles when the stratum is in contact with another agent, so that the oil displacement effect is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield development, and in particular to a self-generated carbon dioxide microbubble oil displacement agent, a preparation method thereof and application thereof. Background Art

[0002] Foam flooding, which effectively expands the swept volume and significantly improves oil washing efficiency, has become an increasingly important method for enhancing oil recovery. A recently developed, self-generating foam flooding technology involves injecting a mixture of salt, a foaming agent, and a foam stabilizer into the formation. Under the formation's temperature and pressure, gas, typically carbon dioxide or nitrogen, spontaneously generates, forming a foam system to enhance oil recovery. Compared to conventional foam flooding technologies, self-generating foam flooding requires less bulky gas injection equipment, requires less space, and requires less investment, making it particularly suitable for offshore platforms with severely limited space.

[0003] The mechanism of autogenous carbon dioxide foam flooding is that the gas generating agent (sodium bicarbonate) and the gas releasing agent (hydrochloric acid) release carbon dioxide through chemical reaction. The chemical reaction formula is as follows:

[0004] NaHCO3+HCl→NaCl+H2O+CO2↑

[0005] Existing techniques typically involve injecting a gasifier solution and a gas release agent solution into the formation in separate slugs. The two solutions come into contact in the formation, generating carbon dioxide for oil recovery. For example, CN103711467A discloses a formula for enhancing the recovery of self-generated CO2. The formula comprises 5-15 parts by weight of ammonium bicarbonate, 1-5 parts of a bioactive agent, and the balance of water not exceeding 35°C. The solution is injected directly into the formation, where it decomposes through formation heat to generate CO2. When the formation temperature is below 35°C, the CO2 is generated through a combined effect with the bioactive agent. This solution can be applied in oilfield flooding, fracturing, and well repair to enhance recovery and promote fracturing fluid flowback. Simultaneously with gas formation, foam is generated, offering high stability, effectively preventing gas channeling, and providing both foam flooding and foam well suppression.

[0006] However, existing foam flooding solutions still have the problems of low oil recovery efficiency and poor oil recovery effect. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a self-generated carbon dioxide microbubble oil displacement agent and its preparation method and use, so as to solve the problems of low oil displacement efficiency and poor oil displacement effect in foam oil displacement scheme.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a self-generated carbon dioxide microbubble oil-displacing agent, the self-generated carbon dioxide microbubble oil-displacing agent comprising:

[0010] Microemulsions, aqueous solutions, and foams with a volume ratio of (0.1-1):(0.1-1):(0.1-1);

[0011] The microemulsion includes a first aerosol, a surfactant, an organic solvent and water;

[0012] The aqueous liquid includes a second gas agent and water;

[0013] The foam liquid comprises a foaming agent, a foam stabilizer and water.

[0014] The self-generated carbon dioxide microbubble oil-displacing agent provided by the present invention utilizes the synergistic effect between its components to achieve excellent oil displacement, thereby significantly improving the oil recovery rate. Furthermore, during the oil recovery process, the sub-agents in the oil-displacing agent are injected as a microemulsion. Due to the controllable dosage of the agent in the microemulsion, trace amounts of carbon dioxide are generated when the sub-agent comes into contact with the formation, forming microbubbles, thereby significantly improving the oil recovery effect.

[0015] As a preferred technical solution of the present invention, the microemulsion includes a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:(0.01-0.5):(10-200):(2-10).

[0016] Preferably, the aqueous liquid comprises the second aerosol and water in a mass ratio of 1:(10-100).

[0017] Preferably, the foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:(0.1-1):(100-300).

[0018] As a preferred technical solution of the present invention, the first gas agent includes carbonate or acid.

[0019] Preferably, the surfactant comprises one or a combination of at least two of sodium lauryl sulfate, sodium ethoxylated alkyl sulfate, cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, Span 80, Tween 80, Tween 60, Tween 20 or OP-10.

[0020] Preferably, the organic solvent comprises one or a combination of at least two of n-butanol, n-hexane, petroleum ether, gasoline, diesel or heavy oil.

[0021] Preferably, the second gaseous agent comprises a carbonate or an acid.

[0022] Preferably, the foaming agent comprises one or a combination of at least two of sodium lauryl sulfate, sodium α-olefin sulfonate, cocamidopropyl betaine, lauryl hydroxysulfobetaine, or lauryl hydroxysulfobetaine.

[0023] Preferably, the foam stabilizer comprises one or a combination of at least two of lauryl alcohol, triethanolamine, carboxymethyl cellulose, polyacrylamide, partially hydrolyzed polyacrylamide or nanoparticles.

[0024] As a preferred technical solution of the present invention, the microemulsion includes a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:(0.04-0.06):(20-40):(2-4).

[0025] Preferably, the foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:(0.1-0.3):100.

[0026] Preferably, the first gaseous agent is an acid, and the second gaseous agent is a carbonate.

[0027] Preferably, the surfactant is Tween 80.

[0028] Preferably, the foaming agent is lauramidopropyl betaine.

[0029] Preferably, the foam stabilizer is partially hydrolyzed polyacrylamide.

[0030] In a second aspect, the present invention provides a method for preparing the self-generated carbon dioxide microbubble oil-displacing agent as described in the first aspect, the preparation method comprising:

[0031] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0032] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0033] The foaming agent, foam stabilizer and water are mixed for the third time to obtain foam liquid.

[0034] As a preferred technical solution of the present invention, the stirring rate of the first stirring and mixing is 300-1000 r / min.

[0035] Preferably, the first stirring and mixing time is 5-50 minutes.

[0036] As a preferred technical solution of the present invention, the stirring rate of the second stirring and mixing is 100-900 r / min.

[0037] Preferably, the second stirring and mixing time is 10-60 minutes.

[0038] As a preferred technical solution of the present invention, the stirring rate of the third stirring and mixing is 200-1000 r / min.

[0039] Preferably, the third stirring and mixing time is 5-60 minutes.

[0040] In a third aspect, the present invention provides a use of the self-generated carbon dioxide microbubble oil-displacing agent as described in the first aspect, wherein the use comprises using the self-generated carbon dioxide microbubble oil-displacing agent to perform oil displacement.

[0041] As a preferred technical solution of the present invention, the oil displacement method includes: injecting foam liquid, water liquid and microemulsion into the formation in sequence.

[0042] Preferably, the injection volume of the foam liquid is 0.1-1PV.

[0043] Preferably, the injection volume of the water liquid is 0.1-1PV.

[0044] Preferably, the injection volume of the microemulsion is 0.1-1 PV.

[0045] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0046] (1) The self-generated carbon dioxide microbubble oil displacement agent provided by the present invention is a drug prepared in the form of a microemulsion and injected. Due to the controllable dosage of the drug in the microemulsion, it can be ensured that a trace amount of carbon dioxide is generated to form microbubbles when the formation contacts the other drug.

[0047] (2) The in-situ self-generated carbon dioxide microbubble flooding method of the present invention can increase the crude oil recovery rate by more than 13 percentage points compared with the conventional carbon dioxide + foam flooding method. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart for using the self-generated carbon dioxide microbubble oil displacement agent provided by an embodiment of the present invention.

[0049] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0050] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0051] This embodiment provides a self-generated carbon dioxide microbubble oil-displacing agent, which comprises:

[0052] Microemulsions, aqueous solutions, and foams with a volume ratio of (0.1-1):(0.1-1):(0.1-1);

[0053] The microemulsion includes a first aerosol, a surfactant, an organic solvent and water;

[0054] The aqueous liquid includes a second gas agent and water;

[0055] The foam liquid comprises a foaming agent, a foam stabilizer and water.

[0056] The oil displacement agent provided by the present invention generates carbon dioxide microbubbles in situ in the formation, and the foam has small size, good stability and high utilization rate, thereby improving the oil displacement effect.

[0057] In the present invention, the self-generated carbon dioxide microbubble oil-displacing agent includes a microemulsion, an aqueous solution and a foam solution in a volume ratio of (0.1-1):(0.1-1):(0.1-1), for example, 0.1:0.1:0.1, 0.2:0.1:0.1, 0.4:0.1:0.1, 0.6:0.1:0.1, 0.8:0.1:0.1, 1:0.1:0.1, 0.1:0.2:0.1, 0.1:0.4:0.1, 0.1:0.6:0.1, 0.1:0.8 :0.1, 0.1:1:0.1, 0.1:0.1:0.2, 0.1:0.1:0.4, 0.1:0.1:0.6, 0.1:0.1:0.8, 0.1:0.1:1, 0.2:0.3:0.5, 0.3:0.4:0.5, 0.4:0.5:0.6, 0.5:0.6:0.7, 0.6:0.8:0.9, 0.5:0.5:1 or 1:1:1, etc., but not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0058] Specifically, the microemulsion includes a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1: (0.01-0.5): (10-200): (2-10), for example, it can be 1: 0.01: 10: 2, 1: 0.05: 50: 3, 1: 0.1: 100: 4, 1: 0.2: 150: 5, 1: 0.3: 200: 6, 1: 0.4: 20: 7, 1: 0.5: 80: 10, 1: 0.5: 10: 5 or 1: 0.1: 150: 5, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0059] Specifically, the aqueous liquid includes a second aerosol and water in a mass ratio of 1:(10-100), for example, it can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90 or 1:100, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0060] Specifically, the foam liquid includes a foaming agent, a foam stabilizer and water in a mass ratio of 1:(0.1-1):(100-300), for example, it can be 1:0.1:100, 1:0.1:100, 1:0.2:100, 1:0.4:100, 1:0.6:100, 1:0.8:100, 1:1:100, 1:0.2:120, 1:0.5:150, 1:0.8:200, 1:1:200, 1:1:300, 1:0.5:300 or 1:0.8:250, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0061] Wherein, the first gas agent includes carbonate or acid.

[0062] The surfactant comprises one or a combination of at least two of sodium lauryl sulfate, sodium ethoxylated alkyl sulfate, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, Span 80, Tween 80, Tween 60, Tween 20 or OP-10.

[0063] The organic solvent comprises one or a combination of at least two of n-butanol, n-hexane, petroleum ether, gasoline, diesel or heavy oil.

[0064] Wherein, the second gas agent includes carbonate or acid.

[0065] In the present invention, the first gaseous agent and the second gaseous agent are used in combination. If the first gaseous agent is an acid, the second gaseous agent is selected to be a carbonate; if the first gaseous agent is a carbonate, the second gaseous agent is an acid.

[0066] The first and second gaseous agents may also be other substances that undergo chemical reactions, such as alkali and ammonium salts that generate ammonia under heating conditions, but the selection of the gaseous agents must ensure that they do not affect the oil displacement effect of the oil displacement agent.

[0067] In the present invention, the carbonate includes soluble carbonates such as sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

[0068] In the present invention, the acid includes inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc., and organic acids such as formic acid, acetic acid, propionic acid, oxalic acid, etc. can also be selected.

[0069] The foaming agent comprises one or a combination of at least two of sodium lauryl sulfate, sodium α-olefin sulfonate, cocamidopropyl betaine, lauryl hydroxysulfobetaine, or lauryl hydroxysulfobetaine.

[0070] Wherein, the foam stabilizer includes lauryl alcohol, triethanolamine, carboxymethyl cellulose, polyacrylamide (molecular weight 5×10 6 ~6×10 6 ), partially hydrolyzed polyacrylamide (molecular weight 1×10 5 ~8×10 5 ) or one or a combination of at least two of nanoparticles.

[0071] In the present invention, the nanoparticles include silicon dioxide, and all particles within the particle size range of 10-500nm can be selected. Specifically, particles of uniform particle size can be selected, or aggregates of particles of all particle sizes within a certain range can be selected, such as aggregates of particles with a particle size of 10nm, aggregates of particles with a particle size of 50nm, aggregates of particles with a particle size of 100nm, aggregates of particles with a particle size of 200nm, aggregates of particles with a particle size of 300nm, aggregates of particles with a particle size of 500nm, etc., or aggregates of particles with all particle sizes within the range of 10-50nm, aggregates of particles with all particle sizes within the range of 40-100nm, aggregates of particles with all particle sizes within the range of 80-150nm, aggregates of particles with all particle sizes within the range of 350-500nm, etc.

[0072] In the present invention, the water used in the self-generated carbon dioxide microbubble oil-displacing agent includes municipal tap water, deionized water, industrial water, or industrial return water that meets the requirements; at the same time, the reagents used to prepare the self-generated carbon dioxide microbubble oil-displacing agent are all commercially available reagents, such as analytical grade reagents, industrial reagents, etc.

[0073] In the present invention, the mass concentration of the acid used in the preparation of the self-generated carbon dioxide microbubble oil displacement agent is 1-5%, for example, it can be 1%, 2%, 3%, 4% or 5%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0074] Furthermore, the present invention provides a method for preparing the aforementioned self-generated carbon dioxide microbubble oil-displacing agent, the preparation method comprising:

[0075] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0076] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0077] The foaming agent, foam stabilizer and water are mixed for the third time to obtain foam liquid.

[0078] The stirring rate of the first stirring and mixing is 300-1000 r / min, for example, it can be 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min or 1000 r / min, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0079] The first stirring and mixing time is 5-50 min, for example, 5 min, 10 min, 20 min, 30 min, 40 min or 50 min, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0080] The stirring rate of the second stirring and mixing is 100-900 r / min, for example, it can be 100 r / min, 200 r / min, 400 r / min, 600 r / min, 800 r / min or 900 r / min, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0081] The second stirring and mixing time is 10-60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0082] Wherein, the stirring rate of the third stirring and mixing is 200-1000r / min, for example, it can be 200r / min, 300r / min, 400r / min, 500r / min, 600r / min, 700r / min, 800r / min, 900r / min or 1000r / min, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0083] The third stirring and mixing time is 5-60 min, for example, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0084] Furthermore, the present invention provides a self-generated carbon dioxide microbubble flooding method, which comprises using the self-generated carbon dioxide microbubble flooding agent to carry out oil displacement.

[0085] Specifically, the oil displacement method includes: injecting foam liquid, water liquid and microemulsion into the formation in sequence; the specific process is as follows Figure 1 shown.

[0086] Among them, the injection volume of the foam liquid is 0.1-1PV, for example, it can be 0.1PV, 0.2PV, 0.3PV, 0.4PV, 0.5PV, 0.6PV, 0.7PV, 0.8PV, 0.9PV or 1PV, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0087] Among them, the injection volume of the water liquid is 0.1-1PV, for example, it can be 0.1PV, 0.2PV, 0.3PV, 0.4PV, 0.5PV, 0.6PV, 0.7PV, 0.8PV, 0.9PV or 1PV, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0088] The injection volume of the microemulsion is 0.1-1PV, for example, it can be 0.1PV, 0.2PV, 0.3PV, 0.4PV, 0.5PV, 0.6PV, 0.7PV, 0.8PV, 0.9PV or 1PV, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0089] Furthermore, in order to illustrate the good oil displacement effect of the self-generated carbon dioxide microbubble oil displacement agent provided by the present invention, actual examples are used for illustration, as follows:

[0090] Example 1

[0091] This embodiment provides a self-generated carbon dioxide microbubble oil-displacing agent, which comprises:

[0092] microemulsion, aqueous solution, and foam solution in a volume ratio of 0.3:0.6:0.4;

[0093] The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:0.2:125:8;

[0094] The aqueous solution includes the second gas agent and water in a mass ratio of 1:30;

[0095] The foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:0.5:150;

[0096] The first aerosol is carbonate (sodium carbonate); the surfactant includes cetyltrimethylammonium bromide; the organic solvent is gasoline; the second aerosol is acid (hydrochloric acid, mass concentration is 2%); the foaming agent is sodium α-olefin sulfonate; and the foam stabilizer is carboxymethyl cellulose.

[0097] The preparation process is as follows:

[0098] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0099] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0100] The foaming agent, the foam stabilizer and the water are mixed for a third time to obtain a foam liquid;

[0101] Among them, the stirring rate of the first stirring and mixing is 500r / min; the time of the first stirring and mixing is 20min; the stirring rate of the second stirring and mixing is 300r / min; the time of the second stirring and mixing is 20min; the stirring rate of the third stirring and mixing is 700r / min; and the time of the third stirring and mixing is 40min.

[0102] Example 2

[0103] This embodiment provides a self-generated carbon dioxide microbubble oil-displacing agent, which comprises:

[0104] microemulsion, aqueous solution, and foam solution in a volume ratio of 0.6:0.3:0.8;

[0105] The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:0.35:50:5;

[0106] The aqueous liquid includes the second gas agent and water in a mass ratio of 1:70;

[0107] The foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:0.8:220;

[0108] The first aerosol is acid (sulfuric acid, with a mass concentration of 3%); the surfactant is sodium lauryl sulfate; the organic solvent is n-hexane; the second aerosol is carbonate (sodium bicarbonate); the foaming agent is lauryl hydroxysulfobetaine; and the foam stabilizer is dodecanol.

[0109] The preparation process is as follows:

[0110] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0111] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0112] The foaming agent, the foam stabilizer and the water are mixed for a third time to obtain a foam liquid;

[0113] Among them, the stirring rate of the first stirring and mixing is 700r / min; the time of the first stirring and mixing is 35min; the stirring rate of the second stirring and mixing is 600r / min; the time of the second stirring and mixing is 40min; the stirring rate of the third stirring and mixing is 400r / min; and the time of the third stirring and mixing is 20min.

[0114] Example 3

[0115] This embodiment provides a self-generated carbon dioxide microbubble oil-displacing agent, which comprises:

[0116] Microemulsion, aqueous solution and foam solution with a volume ratio of 0.1:1:0.1;

[0117] The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:0.01:10:10;

[0118] The aqueous liquid includes the second gas agent and water in a mass ratio of 1:10;

[0119] The foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:0.1:100;

[0120] The first aerosol is carbonate (ammonium carbonate); the surfactant is Span 80; the organic solvent is butanol; the second aerosol is acid (nitric acid, with a mass concentration of 1%); the foaming agent is sodium lauryl sulfate; and the foam stabilizer is triethanolamine.

[0121] The preparation process is as follows:

[0122] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0123] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0124] The foaming agent, the foam stabilizer and the water are mixed for a third time to obtain a foam liquid;

[0125] Among them, the stirring rate of the first stirring and mixing is 300r / min; the time of the first stirring and mixing is 50min; the stirring rate of the second stirring and mixing is 100r / min; the time of the second stirring and mixing is 60min; the stirring rate of the third stirring and mixing is 1000r / min; and the time of the third stirring and mixing is 5min.

[0126] Example 4

[0127] This embodiment provides a self-generated carbon dioxide microbubble oil-displacing agent, which comprises:

[0128] Microemulsion, aqueous solution and foam solution with a volume ratio of 1:1:1;

[0129] The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:0.5:200:2;

[0130] The aqueous liquid includes a second aerosol and water in a mass ratio of 1:100;

[0131] The foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:1:300;

[0132] The first aerosol is acid (hydrochloric acid, with a mass concentration of 5%); the surfactant is OP-10; the organic solvent is heavy oil; the second aerosol is carbonate (ammonium bicarbonate); the foaming agent is cocamidopropyl betaine; and the foam stabilizer is nanoparticle silicon dioxide, with a particle size of 10-50 nm).

[0133] The preparation process is as follows:

[0134] The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion;

[0135] performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution;

[0136] The foaming agent, the foam stabilizer and the water are mixed for a third time to obtain a foam liquid;

[0137] Among them, the stirring rate of the first stirring and mixing is 1000r / min; the time of the first stirring and mixing is 5min; the stirring rate of the second stirring and mixing is 900r / min; the time of the second stirring and mixing is 10min; the stirring rate of the third stirring and mixing is 200r / min; and the time of the third stirring and mixing is 60min.

[0138] Example 5

[0139] The only difference from Example 1 is that the microemulsion comprises the first aerosol, surfactant, organic solvent and water in a mass ratio of 1:0.05:30:3.

[0140] Example 6

[0141] The only difference from Example 1 is that the foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:0.2:100.

[0142] Example 7

[0143] The only difference from Example 1 is that the first aerosol is acid (hydrochloric acid) and the second aerosol is carbonate (sodium carbonate).

[0144] Example 8

[0145] The only difference from Example 1 is that the surfactant is replaced with an equal amount of Tween 80.

[0146] Example 9

[0147] The only difference from Example 1 is that the foaming agent is replaced by an equal amount of lauramidopropyl betaine.

[0148] Example 10

[0149] The only difference from Example 1 is that the foam stabilizer is replaced by an equal amount of partially hydrolyzed polyacrylamide (molecular weight 5×10 5 ).

[0150] Example 11

[0151] The only difference from Example 1 is that the self-generated carbon dioxide microbubble oil-displacing agent is a microemulsion, an aqueous solution and a foam solution in a volume ratio of 0.2:0.3:0.2.

[0152] The self-generated carbon dioxide microbubble flooding agent obtained in Examples 1-10 was used in an oil displacement operation. During the displacement process, a foam solution, a water solution, and a microemulsion were sequentially injected into a simulated well. The oil layer in the simulated well had a porosity of 16.8% and a permeability of 35 mD. The injection rates of the foam solution, water solution, and microemulsion were based on a volume ratio (PV).

[0153] In order to illustrate the performance of the oil-displacing agent provided by the present invention, the following comparative examples are used for illustration:

[0154] Comparative Example 1

[0155] The only difference from Example 1 is that the first gas agent and the second gas agent are mixed and reacted on the ground to generate carbon dioxide foam which is then injected into the formation.

[0156] Comparative Example 2

[0157] The difference from Example 1 is that only water flooding is performed.

[0158] The oil displacement results of the examples and comparative examples are detailed in Table 1.

[0159] Table 1

[0160] Recovery rate / % Example 1 58.2 Example 2 59.1 Example 3 58.7 Example 4 59.2 Example 5 63.5 Example 6 63.2 Example 7 62.5 Example 8 63.0 Example 9 62.8 Example 10 62.4 Example 11 61.3 Comparative Example 1 50.2 Comparative Example 2 39.4

[0161] The results of the above examples and comparative examples demonstrate that the self-generated carbon dioxide microbubble oil-displacing agent provided by the present invention utilizes the synergistic effect between the various components within the oil-displacing agent to achieve excellent oil displacement, thereby significantly improving the oil recovery rate. Furthermore, during the oil-displacing process, the sub-agents in the oil-displacing agent are injected as a microemulsion. Due to the controllable dosage of the agent in the microemulsion, trace amounts of carbon dioxide are generated to form microbubbles when the formation contacts the other agent, thereby significantly improving the oil recovery effect.

[0162] It should be noted that the present invention uses the above-described embodiments to illustrate the detailed structural features of the present invention. However, the present invention is not limited to these detailed structural features, and this does not mean that the present invention must rely on these detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0163] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0164] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0165] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A self-generated carbon dioxide microbubble oil-displacing agent, characterized in that: The self-generated carbon dioxide microbubble oil-displacing agent comprises: Microemulsions, aqueous solutions, and foams with a volume ratio of (0.1-1):(0.1-1):(0.1-1); The microemulsion includes a first aerosol, a surfactant, an organic solvent and water; The aqueous liquid includes a second gas agent and water; The foam liquid comprises a foaming agent, a foam stabilizer and water.

2. The spontaneous carbon dioxide microbubble oil-displacing agent according to claim 1, wherein The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:(0.01-0.5):(10-200):(2-10); Preferably, the aqueous solution comprises the second gas agent and water in a mass ratio of 1:(10-100); Preferably, the foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:(0.1-1):(100-300).

3. The spontaneous carbon dioxide microbubble oil-displacing agent according to claim 1 or 2, wherein The first gaseous agent includes carbonate or acid; Preferably, the surfactant comprises one or a combination of at least two of sodium lauryl sulfate, sodium ethoxylated alkyl sulfate, cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, Span 80, Tween 80, Tween 60, Tween 20 or OP-10; Preferably, the organic solvent comprises one or a combination of at least two of n-butanol, n-hexane, petroleum ether, gasoline, diesel or heavy oil; Preferably, the second gaseous agent comprises a carbonate or an acid; Preferably, the foaming agent comprises one or a combination of at least two of sodium lauryl sulfate, sodium α-olefin sulfonate, cocamidopropyl betaine, lauryl hydroxysulfobetaine, or lauryl hydroxysulfobetaine; Preferably, the foam stabilizer comprises one or a combination of at least two of lauryl alcohol, triethanolamine, carboxymethyl cellulose, polyacrylamide, partially hydrolyzed polyacrylamide or nanoparticles.

4. The spontaneous carbon dioxide microbubble oil-displacing agent according to any one of claims 1 to 3, wherein The microemulsion comprises a first aerosol, a surfactant, an organic solvent and water in a mass ratio of 1:(0.04-0.06):(20-40):(2-4); Preferably, the foam liquid comprises a foaming agent, a foam stabilizer and water in a mass ratio of 1:(0.1-0.3):100; Preferably, the first gaseous agent is an acid and the second gaseous agent is a carbonate; Preferably, the surfactant is Tween 80; Preferably, the foaming agent is lauramidopropyl betaine; Preferably, the foam stabilizer is partially hydrolyzed polyacrylamide.

5. A method for preparing a spontaneous carbon dioxide microbubble oil-displacing agent as described in any one of claims 1 to 4, characterized in that: The preparation method comprises: The first aerosol, the surfactant, the organic solvent and water are first stirred and mixed to obtain a microemulsion; performing a second stirring mixing on the second aerosol and water to obtain an aqueous solution; The foaming agent, foam stabilizer and water are mixed for the third time to obtain foam liquid.

6. The preparation method according to claim 5, characterized in that: The stirring rate of the first stirring and mixing is 300-1000 r / min; Preferably, the first stirring and mixing time is 5-50 minutes.

7. The preparation method according to claim 5 or 6, characterized in that: The stirring rate of the second stirring and mixing is 100-900 r / min; Preferably, the second stirring and mixing time is 10-60 minutes.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The stirring rate of the third stirring and mixing is 200-1000 r / min; Preferably, the third stirring and mixing time is 5-60 minutes.

9. A use of the self-generated carbon dioxide microbubble oil-displacing agent according to any one of claims 1 to 4, characterized in that: The use includes adopting the self-generated carbon dioxide microbubble oil-displacing agent to carry out oil displacement.

10. The use according to claim 9, characterized in that The oil displacement method comprises: injecting foam liquid, water liquid and microemulsion into the formation in sequence; Preferably, the injection volume of the foam liquid is 0.1-1PV; Preferably, the injection volume of the water liquid is 0.1-1PV; Preferably, the injection volume of the microemulsion is 0.1-1 PV.

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