A high-temperature resistant oil displacement foaming agent, its preparation method and application

Abstract

This invention relates to the field of oilfield development technology, specifically to a high-temperature resistant oil displacement foaming agent, its preparation method, and its application. The method involves first preparing a main agent solution containing a high-temperature resistant additive and a main agent, then adding a foam stabilizer for compounding, and finally maturing to obtain the high-temperature resistant oil displacement foaming agent. The main agent includes alkyl aryl sulfonate derivatives, the high-temperature resistant additive is an acrylamide derivative, a styrene derivative, or an organophosphonate, and the foam stabilizer is modified guar gum. The compounding temperature is 120-150℃, the reaction pressure is 0.3-0.5 MPa, and the time is 4-6 hours. This method achieves synergistic effects among the main foaming agent, modified guar gum, and organophosphonate, forming a stable system. This high-temperature resistant oil displacement foaming agent possesses excellent thermal stability and interfacial activity; it exhibits both excellent high-temperature and salt resistance and efficient foaming, foam stabilizing, and oil displacement effects under ultra-high temperature, ultra-high salinity, and high calcium and magnesium ion environments.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and more specifically, to a high-temperature resistant oil displacement foaming agent, its preparation method, and its application. Background Technology

[0002] In oilfield development, oil displacement foaming agents are used to enhance oil recovery. However, due to the special geological conditions of Xinjiang oilfield, such as high temperature and high salinity, existing oil displacement foaming agents have poor stability, weak foaming ability, and insufficient high-temperature resistance, resulting in poor practical application effects and limited improvement in oil recovery.

[0003] To optimize the temperature and salt resistance of oilfield flooding foaming agents, scholars at home and abroad have conducted extensive research, focusing on the modification and application of three types of substances: sulfonate surfactants, such as petroleum sulfonates and α-olefin sulfonates; betaine amphoteric surfactants, such as alkyl betaine and sulfonate betaine; and gemini surfactants.

[0004] However, the existing technology has three major gaps that make these oil displacement foaming agents difficult to adapt to the extreme geological conditions of Xinjiang oilfields: First, current sulfonates, betaines, and gemini surfactants perform poorly under extreme conditions, and no studies have yet been able to achieve long-term stability under synergistic conditions of ultra-high temperature (100-180℃) and ultra-high salt (mineralization of 100,000-200,000 mg / L).

[0005] Secondly, the synergistic performance of foaming, foam stabilization and oil displacement is insufficient. Existing studies mostly focus on optimizing a single performance. Although some modified betaine has improved salt tolerance, its foaming volume and half-life are poor, which cannot meet the needs of the deep heterogeneous strata in Xinjiang Oilfield.

[0006] Third, the formation water in Xinjiang oilfields has high salinity and high Ca content. 2+ Mg 2+ At concentrations of 5000-8000 mg / L, existing foaming agent molecules are prone to forming precipitates with metal ions, leading to loss of interfacial activity. This makes conventional oil displacement foaming agents lack resistance to interference from calcium and magnesium ions under extreme conditions.

[0007] In addition, most related studies focus on Na + K + In a predominantly salty environment, without adaptability design for high calcium and magnesium ion systems, there is a challenge of chain entanglement issues. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a high-temperature resistant oil displacement foaming agent, its preparation method and application.

[0009] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for preparing a high-temperature resistant oil displacement foaming agent, comprising: first, preparing a main agent solution containing a high-temperature resistant additive and a main agent; adding a foam stabilizer to the main agent solution for compounding; and obtaining the high-temperature resistant oil displacement foaming agent after aging. The main agent includes alkyl aryl sulfonate derivatives, the high-temperature resistant additive is an acrylamide derivative, a styrene derivative or an organophosphonate, and the foam stabilizer is modified guar gum. The compounding temperature is 120-150℃, the reaction pressure is 0.3-0.5MPa, and the time is 4-6h.

[0010] Furthermore, the main agent also includes a nonionic surfactant, and the mass ratio of the alkyl aryl sulfonate derivative to the nonionic surfactant is 7:3.

[0011] Furthermore, based on mass parts, the amounts of each raw material are as follows: in the high-temperature resistant oil displacement foaming agent, the mass parts of the high-temperature resistant additive are 3-8 parts, the mass parts of the main agent are 10-15 parts, the mass parts of the foam stabilizer are 2-5 parts, and the mass parts of water used to prepare the main agent solution are 75-85 parts.

[0012] Furthermore, the main agent solution also includes functional additives, including solubilizers and salt-resistant agents; the functional additives are present in 5-10 parts.

[0013] Furthermore, the alkylaryl sulfonate derivative is sodium dodecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, or sodium dinonylnaphthalenesulfonate; The acrylamide derivatives include at least one of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and N,N-dimethylacrylamide; The styrene derivatives include sodium p-styrene sulfonate or sodium α-methylstyrene sulfonate; The organophosphonate is hydroxyethylidene diphosphonic acid; The modified guar gum is hydroxypropyl modified guar gum.

[0014] Furthermore, the following steps are included: S1. Pretreatment stage: Add the high-temperature resistant additive to water at a temperature of 40-50℃ and stir to obtain a basic dispersion; S2. Under stirring conditions, the main agent is added to the basic dispersion in multiple portions, heated to 60-70°C, and stirred continuously to obtain the main agent solution; S3. In an inert gas environment, heat the main agent solution and add the foam stabilizer to perform the compounding, and continue stirring; S4. Lower the temperature to the maturation temperature and perform the maturation while maintaining stirring; S5. The high-temperature resistant oil displacement foaming agent is obtained after natural cooling.

[0015] Furthermore, in step S4, the ripening temperature is 50℃-60℃, the stirring speed is 150-250 r / min, and the time is greater than 2 hours.

[0016] The present invention also provides a high-temperature resistant oil displacement foaming agent, which is prepared by the method described above.

[0017] The present invention also provides the application of the high-temperature resistant oil displacement foaming agent described above in crude oil recovery under high temperature and high salinity conditions.

[0018] Furthermore, the temperature of the high-temperature and high-mineralization conditions is 90℃~330℃, the mineralization TDS is 15000mg / L~200000mg / L, and the sum of calcium ion concentration and magnesium ion concentration is greater than 80mg / L.

[0019] The beneficial effects of this invention are as follows: (1) The preparation method of the high temperature oil displacement foaming agent of the present invention adopts a stepwise dissolution, gradient heating and constant temperature compounding process at 80-90℃. According to the characteristics of each component, the exclusive dissolution conditions are designed to achieve the synergistic effect of the main foaming agent, modified guar gum and organophosphonate. (2) The preparation method of the high-temperature oil displacement foaming agent of the present invention involves aging after compounding to ensure the formation of a stable system; (3) The high-temperature oil displacement foaming agent of the present invention has excellent thermal stability and interfacial activity, and can maintain good foaming performance and oil displacement effect under high temperature conditions. It helps to expand the swept volume and improve the micro-displacement efficiency of the reservoir, thereby significantly improving the crude oil recovery rate. (4) The high-temperature oil displacement foaming agent of the present invention maintains excellent stability after thermal aging under ultra-high temperature, ultra-high salinity and high calcium and magnesium ion environment, has high foam volume retention rate, long foam half-life, low interfacial tension, and effectively improves the core oil recovery rate compared with water displacement. It has both excellent high temperature and salt resistance and efficient foaming and foam stabilizing oil displacement effect. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation method of the high-temperature resistant oil displacement foaming agent of the present invention. Detailed Implementation

[0021] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] The preparation method of the high-temperature resistant oil displacement foaming agent of the present invention involves first preparing a main agent solution containing a high-temperature resistant additive and a main agent; adding a foam stabilizer to the main agent solution for compounding; and obtaining the high-temperature resistant oil displacement foaming agent after aging. The main agent includes alkyl aryl sulfonate derivatives, the high-temperature resistant additive is an acrylamide derivative, a styrene derivative, or an organophosphonate, and the foam stabilizer is modified guar gum. The compounding temperature is 120-150℃, the reaction pressure is 0.3-0.5 MPa, and the time is 4-6 h.

[0023] The preparation method of the high-temperature resistant oil displacement foaming agent of the present invention adopts a stepwise dissolution and constant-temperature compounding process at 120-150℃. Specific dissolution conditions are designed according to the characteristics of each component to ensure the full dissolution of the alkyl aryl sulfonate derivative main foaming agent while avoiding thermal damage. Within this temperature range, the chelating activity of the organophosphonate high-temperature resistant additive is effectively activated, enabling it to efficiently chelate calcium and magnesium ions in the formation, inhibiting oxidative degradation, and preventing excessive swelling and agglomeration of the modified guar gum foam stabilizer. This solves the problem of product performance fluctuations caused by uneven mixing in traditional processes. The problem of foaming was solved, and the synergistic effect of the main foaming agent, modified guar gum and organophosphonate was achieved. The final product maintained excellent stability after 72 hours of thermal aging at 150℃ in the Xinjiang oilfield with ultra-high salinity of 5-200,000 mg / L and high calcium and magnesium ion content. The foam volume retention rate exceeded 90%, the foam half-life reached more than 32 minutes, the interfacial tension dropped to 0.08 mN / m, and the core flooding oil recovery rate increased by 18.5% compared with water flooding. It has the advantages of excellent high temperature and salt resistance and efficient foaming and foam stabilization oil displacement effect.

[0024] The key control points of the preparation method of this invention are as follows: First, the high-temperature resistant additive needs to be added before the foam stabilizer to prevent the foam stabilizer from reacting with the additive prematurely; second, the compounding temperature is precisely controlled at 120-150℃ to avoid guar gum degradation or affecting the activity of the additive; third, after compounding, it is matured to ensure the formation of a stable system.

[0025] Preferably, the main agent also includes a nonionic surfactant, and the mass ratio of the alkyl aryl sulfonate derivative to the nonionic surfactant is 7:3; the nonionic surfactant can be compounded with the alkyl aryl sulfonate derivative to improve foam stability.

[0026] Preferably, the nonionic surfactant includes fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether, which can be compounded with sulfonates to improve foam stability.

[0027] Preferably, in the high-temperature resistant oil displacement foaming agent, the mass fraction of the high-temperature resistant additive is 3-8 parts, the mass fraction of the main agent is 10-15 parts, the mass fraction of the foam stabilizer is 2-5 parts, and the mass fraction of water is 75-85 parts.

[0028] Preferably, the main agent solution also includes functional additives, including a solubilizer and a salt-resistant agent; the functional additives are 5-10 parts. Specifically, the solubilizer is urea, with a mass fraction of 2-3 parts, which can improve the compatibility of each component, and the salt-resistant agent is sodium citrate, with a mass fraction of 3-7 parts, which is suitable for high-salinity oil reservoirs.

[0029] Preferably, the alkylaryl sulfonate derivatives are sodium dodecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, or sodium dinonylnaphthalenesulfonate. Among them, sodium hexadecylbenzenesulfonate has the best temperature resistance and is suitable for oil reservoirs above 150°C.

[0030] Acrylamide derivatives include at least one of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and N,N-dimethylacrylamide; these derivatives can be used alone or in combination, with a recommended mass ratio of 3:5:2 when in combination.

[0031] Styrene derivatives include sodium p-styrene sulfonate or sodium α-methylstyrene sulfonate; their temperature resistance can reach over 180℃, making them suitable for high-temperature oil reservoir environments.

[0032] Organophosphonates possess high temperature resistance and salt tolerance, which can synergistically improve the stability of the finished product in high-salinity oil reservoirs; preferably, the organophosphonate is hydroxyethylidene diphosphonic acid.

[0033] The modified guar gum is hydroxypropyl-modified guar gum, which can improve foam stability and extend the foam half-life. Preferably, the degree of crosslinking of the hydroxypropyl-modified guar gum is 18%.

[0034] Preferred, such as Figure 1 As shown, the preparation method of the present invention includes the following steps: S1. Pretreatment stage: At a temperature of 40-50℃, add a high-temperature resistant additive to water and stir to obtain a basic dispersion.

[0035] In this step, the stirring speed is 300-400 r / min and the time is 15 min. After stirring, the high-temperature resistant additive is completely dissolved.

[0036] Preferably, when functional additives are present, each functional additive is also added in this step.

[0037] S2. Under stirring conditions, the alkyl aryl sulfonate derivative is added to the basic dispersion in multiple portions. After the addition is complete, the mixture is heated to 60-70°C and stirred continuously to obtain the main agent solution.

[0038] The specific operation of this step is as follows: while maintaining the stirring speed, add the alkyl aryl sulfonate derivative to the basic dispersion in 3-5 portions, with an interval of 5 minutes between each addition. After the addition is complete, raise the temperature to 60-70℃ and stir for 30 minutes to completely dissolve the main foaming agent and form a homogeneous solution.

[0039] Preferably, this step also includes the addition of nonionic surfactants multiple times.

[0040] S3. Heat the main agent solution to the compounding temperature, then add the foam stabilizer and continue stirring.

[0041] The specific operation of this step is as follows: nitrogen gas is introduced into the reactor, the reactor is heated to 120-150℃, the modified guar gum foam stabilizer is slowly added, the stirring speed is increased to 500-600 r / min, the reaction pressure is 0.3-0.5 MPa, and the time is 4-6 h; these conditions can promote chelation activity and avoid excessive swelling of guar gum.

[0042] S4. Lower the temperature to the maturation temperature and continue maturation while stirring.

[0043] The specific operation of this step is as follows: turn off the heating, keep stirring at 150-250 r / min, reduce the temperature to 50℃-60℃, keep it warm and cook it, take a sample for testing after cooking, and if there is no layering or sedimentation, it is the finished product.

[0044] Preferably, the maturation time is no less than 2 hours, and the optimal time is 4-16 hours.

[0045] S5. After natural cooling, a high-temperature resistant oil displacement foaming agent is obtained.

[0046] The high-temperature resistant oil displacement foaming agent of the present invention is prepared by the method described above. This high-temperature resistant oil displacement foaming agent has excellent thermal stability and interfacial activity, and can maintain good foaming performance and oil displacement effect under high temperature conditions. It helps to expand the swept volume and improve the micro-displacement efficiency of the reservoir, thereby significantly improving the crude oil recovery rate.

[0047] This high-temperature resistant oil displacement foaming agent can be used in crude oil recovery under high-temperature and high-salinity conditions. These conditions include temperatures ranging from 90℃ to 330℃, a total dissolved solids (TDS) of 15000 mg / L to 200000 mg / L, and a combined calcium and magnesium ion concentration greater than 80 mg / L.

[0048] The effects of the present invention will be illustrated below through specific embodiments and comparative examples.

[0049] Example 1 This embodiment uses the method of the present invention to prepare a high-temperature resistant oil displacement foaming agent and conducts performance tests.

[0050] In this embodiment, the main foaming agent is industrial-grade sodium dodecylbenzenesulfonate (DBS), the foam stabilizer is hydroxypropyl-modified guar gum with a crosslinking degree of 18%, and the high-temperature resistant additive is hydroxyethylidene diphosphonic acid (HEDP), also of industrial grade. The solvent is deionized water. The mass percentages of the above components are shown in Table 1. Table 1 The preparation process uses a sealed reaction vessel with stirring and temperature control functions. The specific preparation process is as follows: Pretreatment stage: Add deionized water to the reactor, start stirring, set the speed to 350 r / min, slowly heat to 45℃, then slowly add HEDP, and continue stirring for 15 min until completely dissolved to form the base solution.

[0051] Main agent dissolution stage: While stirring, add DBS in 4 portions, with 5-minute intervals between each addition. After all the DBS has been added, raise the temperature to 65°C and continue stirring for 30 minutes until a homogeneous and transparent solution is formed.

[0052] Additive compounding stage: Under nitrogen atmosphere, the temperature is further increased to 125℃, modified guar gum is added, and the stirring speed is increased to 550 r / min. The pressure is maintained at 0.5MPa, and stirring is continued for 5 hours to ensure uniform dispersion of each component.

[0053] Maturation and cooling stage: Reduce the reaction temperature to 50°C, maintain a stirring speed of 200 r / min, and mature at this temperature for 4 h.

[0054] The system was naturally cooled to room temperature (25±2℃). No stratification or precipitation occurred in the final system, and a light yellow transparent liquid product was obtained, which is the high-temperature resistant oil displacement foaming agent.

[0055] The high-temperature resistant oil displacement foaming agent obtained in this embodiment was tested using a foam performance tester, a high-temperature aging chamber, and a core displacement experimental device. The specific test conditions and results are shown in Table 2.

[0056] Table 2 The test results above show that the high-temperature resistant oil displacement foaming agent prepared in this embodiment exhibits excellent foaming properties, foam stabilization and oil displacement effect under high temperature (150℃), high salinity (50,000-80,000 mg / L) and high calcium and magnesium ion environment. It can meet the application needs of extreme geological conditions in Xinjiang oilfield and has significant potential for field application.

[0057] Example 2 The preparation process of this embodiment is the same as that of Example 1. The main agent is a compound mixture of industrial-grade sodium dodecylbenzenesulfonate (DBS) and alkylphenol polyoxyethylene ether. The foam stabilizer is hydroxypropyl modified guar gum with a crosslinking degree of 18%. The high-temperature resistant additive is hydroxyethylidene diphosphonic acid (HEDP), which is also industrial-grade. The solvent is deionized water. Functional additives are also included, which are added during the pretreatment stage.

[0058] The mass percentage of each component is shown in Table 3: Table 3 This embodiment was tested using the same testing method as in Example 1, and the test results are shown in Table 4: Table 4 The test results above show that the high-temperature resistant oil displacement foaming agent prepared in this embodiment is similar to that in Example 1, with excellent foaming properties, foam stabilization and oil displacement effect. It can also meet the application requirements of the extreme geological conditions in Xinjiang Oilfield and has significant potential for field application.

[0059] Comparative Example 1: Conventional sulfonate foaming agents In this comparative example, the conventional sulfonate foaming agent was selected as α-olefin sulfonate (AOS, C14-C16), accounting for 15%; the foam stabilizer was unmodified guar gum, accounting for 2%; and the solvent was deionized water, accounting for 83%.

[0060] The specific preparation method for this comparative example is as follows: stirring and mixing at room temperature for 30 minutes, without any special ripening process.

[0061] The conventional sulfonate foaming agent obtained in this comparative example was tested using a foam performance tester, a high-temperature aging chamber, and a core displacement experimental device. The specific test conditions and results are shown in Table 5.

[0062] Table 5 The test results above show that the foaming agent has insufficient high-temperature resistance. After high-temperature aging, its foaming ability decreases by more than 50%.

[0063] Meanwhile, this foaming agent is prone to precipitation in a high calcium and magnesium ion environment, which affects the stability of the system.

[0064] In addition, the foam stabilizer uses unmodified guar gum, resulting in poor foam stabilization performance and a short foam half-life.

[0065] Comparative Example 2: Betaine-based foaming agents In this comparative example, the main agent of the betaine-based foaming agent is cocamidopropyl betaine (CAB), accounting for 12%; the foam stabilizer is partially hydrolyzed polyacrylamide (HPAM, molecular weight 8 million), accounting for 0.5%; the salt-resistant additive is sodium citrate, accounting for 3%; and the solvent is deionized water, accounting for 84.5%.

[0066] The specific preparation method for this comparative example is as follows: the mixture is stirred and dissolved at 50°C, and this temperature is maintained during stirring, without gradient heating or aging processes.

[0067] The conventional sulfonate foaming agent obtained in this comparative example was tested using a foam performance tester, a high-temperature aging chamber, and a core displacement experimental device. The specific test conditions and results are shown in Table 6.

[0068] Table 6 The test results above show that betaine is prone to molecular structure degradation under high temperature conditions, leading to decreased foaming stability. Sodium citrate has limited chelating ability for high concentrations of calcium and magnesium ions. HPAM is easily hydrolyzed under high temperature and high salt conditions, significantly weakening its foam-stabilizing effect.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a high-temperature-tolerant oil displacement foaming agent, characterized in that, A main agent solution containing a high-temperature-resistant assistant and a main agent is prepared first; a foam stabilizer is added to the main agent solution for re-compounding; and the high-temperature-resistant oil displacement foam agent is obtained after aging; The main agent comprises an alkyl aryl sulfonate derivative, the high-temperature-resistant assistant is an acrylamide derivative, a styrene derivative or an organic phosphonate, and the foam stabilizer is modified guar gum. The re-compounding temperature is 120-150℃, the reaction pressure is 0.3-0.5MPa, and the time is 4-6h.

2. A process for the preparation of a high temperature resistant oil displacement foaming agent as claimed in claim 1, wherein, The main agent further comprises a non-ionic surfactant, and the mass ratio of the alkyl aryl sulfonate derivative to the non-ionic surfactant is 7:

3.

3. A process for the preparation of a high temperature resistant oil displacement foaming agent as claimed in claim 1, wherein, In terms of mass fraction, the amounts of the raw materials are as follows: in the high-temperature-resistant oil displacement foam agent, the mass fraction of the high-temperature-resistant assistant is 3-8 parts, the mass fraction of the main agent is 10-15 parts, the mass fraction of the foam stabilizer is 2-5 parts, and the mass fraction of water used for preparing the main agent solution is 75-85 parts.

4. A process for the preparation of a high temperature resistant oil displacement foaming agent as claimed in claim 3, wherein, The main agent solution further comprises a functional assistant, and the functional assistant comprises a dissolution aid and a salt resistance agent; the functional assistant is 5-10 parts.

5. The preparation method of a high-temperature resistant oil displacement foaming agent according to claim 1, characterized in that, The alkyl aryl sulfonate derivative is sodium dodecyl benzene sulfonate, sodium tetradecyl benzene sulfonate, sodium hexadecyl benzene sulfonate or sodium dinonyl naphthalene sulfonate; The acrylamide derivative comprises at least one of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and N,N-dimethyl acrylamide; The styrene derivative comprises sodium p-styrene sulfonate or sodium α-methyl styrene sulfonate; The organic phosphonate is hydroxyethylidene diphosphonic acid; The modified guar gum is hydroxypropyl modified guar gum.

6. The method for preparing a high-temperature-resistant oil displacement foaming agent according to any one of claims 1-5, characterized in that, The method comprises the following steps: S1, a pretreatment stage: a high-temperature-resistant assistant is added to water at a temperature of 40-50℃ and stirred to obtain a base dispersion; S2, under stirring, the main agent is added to the base dispersion in multiple times, heated to 60-70℃ and continuously stirred to obtain a main agent solution; S3, in an inert gas environment, the main agent solution is heated and the foam stabilizer is added for re-compounding and continuous stirring; S4, the temperature is reduced to an aging temperature, and the aging is carried out under the condition of keeping stirring; S5, the high-temperature-resistant oil displacement foam agent is obtained after natural cooling.

7. The preparation method of a high-temperature resistant oil displacement foaming agent according to claim 6, characterized in that, In step S4, the aging temperature is 50-60℃, the stirring speed is 150-250r / min, and the time is greater than 2h.

8. A high temperature resistant oil displacement foam agent characterized by, The method is prepared by the method of any one of claims 1-6.

9. The high-temperature-resistant oil displacement foam agent of claim 7 is used for oil recovery under high-temperature and high-salinity conditions.

10. Use of the high temperature resistant oil displacement foaming agent according to claim 8 for oil recovery under high temperature and high salinity conditions, characterized in that, The high-temperature and high-salinity conditions have a temperature of 90-330℃, a salinity TDS of 15000-200000mg / L, and a total concentration of calcium ions and magnesium ions greater than 80mg / L.

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