CO2 gas displacement channeling sealing agent, preparation method and application thereof

Abstract

The application belongs to the technical field of oilfield exploitation, and particularly relates to a CO2 gas flooding channeling blocking agent, a preparation method and application thereof. Raw materials of the CO2 gas flooding channeling blocking agent include a surfactant, a gemini tertiary amine and water, wherein the gemini tertiary amine is obtained by reacting N,N-methylene bisacrylamide with a secondary amine. The responsive gel channeling blocking agent has good injection performance, is simple to prepare, has performance that can be flexibly regulated, has less reservoir damage, has good thickening performance under CO2 conditions, can effectively block the matrix, and the blocking rate is more than 95%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield exploitation, and particularly relates to a CO2 gas flooding channeling blocking agent and a preparation method and application thereof. BACKGROUND

[0002] The recovery degree of super-low permeability reservoirs relying on natural energy is generally less than 10%. To improve the recovery degree of the reservoirs, the reservoir energy must be supplemented by water injection or gas injection. Since a hydration film is easily formed in the process of water injection, the clay minerals in the formation swell when they come into contact with water, and the pores tend to close, which leads to a rapid rise in the injection pressure, a significant reduction in the injection volume, and even the failure of water injection, resulting in a low matrix producing degree. Compared with water injection, gas injection is easy to enter the micro-nano pores, and can effectively displace the crude oil in the matrix, significantly improving the oil displacement efficiency. In particular, CO2 gas is more soluble in water than general hydrocarbon gases, and the solubility of CO2 in the crude oil is greater than that in water. CO2 can be transferred from the aqueous solution to the crude oil, and has the advantages of easy flow, viscosity reduction, volume expansion, interfacial tension reduction, acidification, plugging removal, extraction of light hydrocarbons, and easy miscibility, etc. Therefore, CO2 flooding has been widely concerned at home and abroad as an effective means for enhancing oil recovery in low-permeability reservoirs.

[0003] Most of the oil reservoirs in China are continental deposits, and the heterogeneity is serious. In the process of CO2 gas flooding, the gas channeling is easily caused due to the influence of factors such as gas slip effect, viscous fingering, and reservoir heterogeneity, and the gas channeling conditions vary greatly. Generally, there are problems such as channeling in large pores and breakthrough in high-permeability layers. Early breakthrough of injected CO2 will lead to the fact that most of the reservoirs are not swept, and the development of the oil reservoir by CO2 injection is difficult to achieve the expected development effect. Therefore, before CO2 gas flooding, it is important to effectively block the high-permeability layers to prevent gas channeling along the high-permeability zones during CO2 gas flooding.

[0004] Chinese patent application CN202010262672.5 discloses a foam channeling blocking agent for CO2 flooding of heavy oil reservoirs and a preparation method and application thereof, and belongs to the technical field of CO2 flooding of heavy oil reservoirs. The technical problems of complex process, poor foaming capacity, and poor stability of the existing foam channeling blocking agent can be solved. In the foam channeling blocking agent for CO2 flooding of heavy oil reservoirs, the mass concentration of alpha-alkenyl sulfonate is 40-60%, the mass concentration of quaternary ammonium salt type imidazoline is 10-20%, the mass concentration of hydroxyethyl cellulose is 3-5%, the mass concentration of Na5P3O10 is 10-15%, and the balance is water. The application can effectively control gas channeling and fluidity, thereby improving the swept volume of CO2 flooding, achieving the purpose of profile control and equal fluidity control, and achieving the goal of improving the recovery rate. However, the foam channeling blocking agent has a large difficulty in field construction. The foam formed on the ground cannot be injected, and the quality and quantity of the foam formed underground are difficult to guarantee. 10

[0005] ​Chinese invention patent application CN201410662306.3 discloses a CO2 drive high-temperature low-permeability water-sensitive oil reservoir organic particle plugging agent and a preparation method thereof. The plugging agent is composed of organic phenol, formaldehyde, furfural, p-toluene sulfonic acid, organic alcohol and dispersant. The isolation plug is gas: N2 or CO2. The plugging agent is mainly formed by carbonyl addition and condensation reaction of the above raw materials under the action of a catalyst to form a polymer with furan methylene as a bridge and furan hydroxymethyl as a terminal group. The organic gel particles are synthesized by a solution-sol-gel method under an acid or supercritical CO2 atmosphere. When the polymer molecules increase to a certain extent and exceed the solubility, the polymer molecules coagulate to form organic particles. However, the synthesis process of the product involves many toxic substances, and the preparation process is relatively complex.

[0006] In view of the problems existing in the CO2 gas drive process of high-temperature low-permeability oil reservoirs, a temperature-resistant, salt-resistant and easy-to-inject channeling plugging agent with excellent performance is developed, which is an urgent need to improve the CO2 displacement effect. Therefore, a new temperature-resistant, salt-resistant and easy-to-inject channeling plugging agent needs to be developed. SUMMARY

[0007] Based on the above deficiencies, the present application provides a CO2 gas drive channeling plugging agent, a preparation method and application thereof. The present application prepares a gemini tertiary amine, which has CO2 responsiveness. When CO2 is introduced, the gemini tertiary amine is protonated to have positive charges at both ends of the molecule, and then self-assembles with a surfactant in a solution under the action of electrostatic attraction to form a CO2-responsive gel, which can be used as a CO2 drive responsive gel channeling plugging agent. It is especially suitable for use in the production of CO2-responsive gel channeling plugging agents for tight oil reservoirs.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A CO2 gas drive channeling plugging agent, the raw materials of the CO2 gas drive channeling plugging agent include a surfactant, a gemini tertiary amine and water, wherein the gemini tertiary amine is obtained by reacting N,N-methylene bisacrylamide with a secondary amine.

[0010] Preferably, the chemical structure of the gemini tertiary amine is as follows:

[0011]

[0012] wherein R1 and R2 are both C n H 2n+1 .

[0013] Preferably, the raw materials of the CO2 gas drive channeling plugging agent include 1%-5% of the surfactant, 1%-5% of the gemini tertiary amine and the balance of water in terms of weight percentage.

[0014] Preferably, the surfactant is selected from one or more of sodium dodecyl sulfate, sodium alpha-olefin sulfonate and sodium fatty acid methyl ester sulfonate.

[0015] The synthesis route of the geminal tertiary amine is as follows:

[0016] Preferably, the molar ratio of the N,N-methylene bisacrylamide to the secondary amine is 1:1-3.

[0017] Preferably, the secondary amine is selected from any one of dimethylamine, dipropylamine and diisopropylamine.

[0018]

[0019] The geminal tertiary amine has CO2 responsiveness. When CO2 is introduced, the geminal tertiary amine is protonated to have positive charges at both ends of the molecule, and then self-assembles with the surfactant under electrostatic attraction in the solution to form a CO2-responsive gel, which can be used as a CO2 flooding response gel channeling prevention agent.

[0020] The present application also relates to a preparation method of the CO2 gas flooding channeling prevention agent, comprising the following steps:

[0021] (1) mixing N,N-methylene bisacrylamide, a secondary amine and water, reacting to obtain a geminal tertiary amine;

[0022] (2) mixing the geminal tertiary amine, a surfactant and water to obtain the CO2 gas flooding channeling prevention agent.

[0023] Preferably, the temperature of the reaction in step (1) is 20-80℃, and the reaction time is 20-28h.

[0024] Preferably, after the reaction in step (1), the step of removing the secondary amine by rotary evaporation is further included.

[0025] The present application also relates to the application of the CO2 gas flooding channeling prevention agent in oil reservoir exploitation as a channeling prevention agent.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The response gel channeling prevention agent of the present application has good injection performance;

[0028] (2) The response gel channeling prevention agent of the present application is simple to prepare, and its performance can be flexibly controlled, and it has less reservoir damage;

[0029] (3) The response gel channeling prevention agent of the present application has good thickening performance under CO2 conditions, and can effectively plug the matrix with a plugging rate of more than 95%. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application are further described clearly, the described embodiments are only a part of the present application, used for explaining the present application, but not used for limiting the present application, therefore the other embodiments obtained by other skilled persons in the art without creative labor, all belong to the protection scope of the present application.

[0031] Sodium dodecyl sulfate, sodium alpha-olefin sulfonate, sodium fatty acid methyl ester sulfonate and lauryl amidopropyl betaine are all purchased from Chengdu Kolon Chemical Co., Ltd.

[0032] Example 1

[0033] The CO2 gas channeling blocking agent is prepared by mixing 3wt% of sodium dodecyl sulfate, 1wt% of Gemini tertiary amine A and 96wt% of water.

[0034] Preparation method:

[0035] (1) N,N-methylene bisacrylamide is reacted with dimethylamine aqueous solution at 20℃ for 24h, wherein the molar ratio of N,N-methylene bisacrylamide to dimethylamine is 1:2;

[0036] (2) After reaction, the excess dimethylamine is removed by rotary evaporation to obtain Gemini tertiary amine A;

[0037] (3) 3wt% of sodium dodecyl sulfate, 1wt% of Gemini tertiary amine A and 96wt% of water are mixed uniformly to obtain the CO2 gas channeling blocking agent.

[0038] Example 2

[0039] The CO2 gas channeling blocking agent is prepared by mixing 4wt% of sodium alpha-olefin sulfonate, 2wt% of Gemini tertiary amine B and 94wt% of water.

[0040] Preparation method:

[0041] (1) N,N-methylene bisacrylamide is reacted with dimethylamine aqueous solution at 30℃ for 24h, wherein the molar ratio of N,N-methylene bisacrylamide to dimethylamine is 1:3;

[0042] (2) After reaction, the excess dimethylamine is removed by rotary evaporation to obtain Gemini tertiary amine B;

[0043] (3) 4wt% of sodium alpha-olefin sulfonate, 2wt% of Gemini tertiary amine B and 94wt% of water are mixed uniformly to obtain the CO2 gas channeling blocking agent.

[0044] Example 3

[0045] The CO2 gas channeling blocking agent is prepared by mixing 5wt% of sodium fatty acid methyl ester sulfonate, 1.5wt% of Gemini tertiary amine C and 93.5wt% of water.

[0046] Preparation method:

[0047] (1) reacting N,N-methylenebisacrylamide with an aqueous solution of diisopropylamine at 50°C for 24 hours, wherein the molar ratio of N,N-methylenebisacrylamide to dimethylamine is 1:2;

[0048] (2) After the reaction, remove the excess diisopropylamine by rotary evaporation to obtain the gemini tertiary amine C;

[0049] (3) 5 wt% of sodium fatty acid methyl ester sulfonate, 1.5 wt% of gemini tertiary amine C and 96 wt% of water were mixed uniformly to obtain a CO2 gas flooding sealing agent.

[0050] Example 4

[0051] The raw materials of CO2 gas flooding sealing agent are: 4% sodium fatty acid methyl ester sulfonate, 1% gemini tertiary amine D and 95% water, calculated by weight percentage.

[0052] Preparation method:

[0053] (1) reacting N,N-methylenebisacrylamide with an aqueous solution of diisopropylamine at 60°C for 24 hours, wherein the molar ratio of N,N-methylenebisacrylamide to dimethylamine is 1:3;

[0054] (2) After the reaction, remove the excess diisopropylamine by rotary evaporation to obtain the gemini tertiary amine D;

[0055] (3) 4 wt% of sodium fatty acid methyl ester sulfonate, 1 wt% of gemini tertiary amine D and 95 wt% of water were mixed uniformly to obtain a CO2 gas flooding sealing agent.

[0056] Example 5

[0057] The raw materials of CO2 gas flooding sealing agent are calculated by weight percentage: 2% sodium lauryl sulfate, 3% sodium fatty acid methyl ester sulfonate, 2% gemini tertiary amine E and 93% water.

[0058] Preparation method:

[0059] (1) reacting N,N-methylenebisacrylamide with a dipropylamine aqueous solution at 70°C for 24 hours, wherein the molar ratio of N,N-methylenebisacrylamide to dipropylamine is 1:1.5;

[0060] (2) After the reaction, the excess dipropylamine was removed by rotary evaporation to obtain the gemini tertiary amine E;

[0061] (3) 2 wt% of sodium lauryl sulfate, 3 wt% of sodium fatty acid methyl ester sulfonate, 2 wt% of gemini tertiary amine E and 93 wt% of water were mixed uniformly to obtain a CO2 gas flooding sealing agent.

[0062] Example 6

[0063] The CO2 gas channeling blocking agent is prepared from 5% sodium dodecyl sulfate, 5% Gemini tertiary amine F and 90% water by weight.

[0064] Preparation method:

[0065] (1) N,N-methylene bisacrylamide is reacted with a water solution of dipropylamine at 80°C for 24 h, wherein the molar ratio of N,N-methylene bisacrylamide to dipropylamine is 1:3;

[0066] (2) After the reaction, the excess dipropylamine is removed by rotary evaporation to obtain the Gemini tertiary amine F;

[0067] (3) 5% sodium dodecyl sulfate, 5% Gemini tertiary amine F and 90% water are mixed to obtain the CO2 gas channeling blocking agent.

[0068] Comparative Example 1

[0069] The CO2 gas channeling blocking agent is prepared from 5% sodium dodecyl sulfate, 5% N,N-methylene bisacrylamide, 2.5% dipropylamine and 87.5% water by weight.

[0070] Preparation method:

[0071] Sodium dodecyl sulfate, N,N-methylene bisacrylamide, dipropylamine and water are mixed to obtain the CO2 gas channeling blocking agent.

[0072] Comparative Example 2

[0073] The CO2 gas channeling blocking agent is prepared from 5% sodium dodecyl benzene sulfonate, 5% Gemini tertiary amine F and 90% water by weight.

[0074] Preparation method:

[0075] (1) N,N-methylene bisacrylamide is reacted with a water solution of dipropylamine at 80°C for 24 h, wherein the molar ratio of N,N-methylene bisacrylamide to dipropylamine is 1:3;

[0076] (2) After the reaction, the excess dipropylamine is removed by rotary evaporation to obtain the Gemini tertiary amine F;

[0077] (3) 5% sodium dodecyl benzene sulfonate, 5% Gemini tertiary amine F and 90% water are mixed to obtain the CO2 gas channeling blocking agent.

[0078] Comparative Example 3

[0079] The CO2 gas channeling blocking agent is prepared from 5% sodium dodecyl sulfate, 5% Gemini tertiary amine H and 90% water by weight.

[0080] Preparation method:

[0081] (1) N,N-methylene-bis-acrylamide was reacted with diacetone acrylamide aqueous solution at 80℃ for 24h, wherein the molar ratio of N,N-methylene-bis-acrylamide to diacetone acrylamide was 1:3;

[0082] (2) After reaction, the excess diacetone acrylamide was removed by rotary evaporation to obtain Gemini tertiary amine H;

[0083] (3) 5wt% sodium dodecyl sulfate, 5wt% Gemini tertiary amine H and 90wt% water were mixed uniformly to obtain the CO2 gas channeling blocking agent.

[0084] Comparative example 4

[0085] The CO2 gas channeling blocking agent was prepared by mixing 5wt% sodium dodecyl sulfate, 5wt% Gemini tertiary amine F mixture and 90wt% water.

[0086] Preparation method:

[0087] (1) N,N-methylene-bis-acrylamide was reacted with diacetone acrylamide aqueous solution at 80℃ for 24h, wherein the molar ratio of N,N-methylene-bis-acrylamide to diacetone acrylamide was 1:3;

[0088] (2) After reaction, the excess diacetone acrylamide was removed by rotary evaporation to obtain Gemini tertiary amine H;

[0089] Effect test

[0090] The CO2 gas channeling blocking agents in examples 1-6 and comparative examples 1-4 were respectively tested for performance, and the specific method was as follows:

[0091] 1. Viscosity increasing performance test

[0092] The test method was as follows: 1) the CO2 gas channeling blocking agent was weighed and added into distilled water in a beaker, stirred uniformly, and the initial viscosity was tested by an NDJ rotary viscometer; 2) CO2 was introduced into the beaker while stirring until the viscosity no longer changed, and the CO2 responsive gel was obtained, and then the viscosity was tested by an NDJ rotary viscometer.

[0093] 2. Blocking performance test

[0094] The test method is: 1) washing the core with a mixture of ethanol and toluene for 3-4 days, drying, and determining the basic data of the core; 2) saturating the core with crude oil; 3) placing the core in a holder, adding a confining pressure of 10 MPa, injecting CO2 at a certain flow rate until the core gas is out, and recording the gas out pressure P1 at this time; 4) injecting 0.8 PV of CO2 gas displacement channeling agent solution, and allowing the CO2 gas displacement channeling agent to gel in a CO2 atmosphere for 30 min; 5) passing in CO2 at a certain flow rate, and recording the breakthrough pressure P2 when it breaks through; and 6) calculating the plugging rate through the pressure change before and after.

[0095] Table 1: Performance test results of CO2 gas displacement channeling agent

[0096]

[0097]

[0098] The above detailed description is a specific description of one of the feasible embodiments of the present application, and is not used to limit the patent scope of the present application. Any equivalent implementation or change without departing from the present application shall be included in the scope of the technical scheme of the present application.

Claims

1. A CO2 gas flooding channeling sealing agent, characterized by, The raw materials of the CO2 gas flooding channeling blocking agent by weight percentage include: 1%-5% of a surfactant, 1%-5% of a geminal tertiary amine, and the balance of water, wherein the geminal tertiary amine is obtained by reacting N,N-methylene bisacrylamide with a secondary amine; The chemical structure of the geminal tertiary amine is as follows: ； wherein R1, R2are both C n H 2n+1 ; The surfactant is selected from one or more of sodium dodecyl sulfate, sodium alpha-olefin sulfonate, and sodium fatty acid methyl ester sulfonate; The molar ratio of the N,N-methylene bisacrylamide to the secondary amine is 1:1-3.

2. The CO2 gas flooding channeling sealing agent according to claim 1, characterized in that, The secondary amine is selected from any one of dimethylamine, dipropylamine, and diisopropylamine.

3. A method of preparing the CO2 gas channeling blocking agent according to any one of claims 1 to 2, characterized by, The method comprises the following steps: (1) mixing N,N-methylene bisacrylamide, a secondary amine, and water, and reacting to obtain a geminal tertiary amine; (2) mixing the geminal tertiary amine, a surfactant, and water to obtain the CO2 gas flooding channeling blocking agent.

4. The production method according to claim 3, characterized by, The reaction temperature in step (1) is 20-80℃, and the reaction time is 20-28h.

5. The preparation method according to claim 3, characterized in that After the reaction in step (1), a step of removing the secondary amine by rotary evaporation is further included.

6. Use of the CO2 gas flooding channeling blocking agent of any one of claims 1-2 as a channeling blocking agent in oilfield reservoir exploitation.

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