Polyacrylamide binary composite composition for oil displacement and preparation method thereof

Abstract

The invention discloses an oil displacement polyacrylamide binary composite composition which comprises the following components in percentage by mass: 0.5%-2.0% of polyacrylamide, 3.0%-5.0% of a zwitterionic surfactant, 20%-40% of polysiloxane, 4.0%-8.0% of a suspending agent, 5.0%-10.0% of a penetrant, 1.0%-2.0% of a high-temperature stabilizer and the balance of water. The invention also discloses a preparation method thereof. The invention has the advantages that polysiloxane is adopted as a dispersion system, so that the surface tension is reduced while high temperature resistance is realized; the zwitterionic surfactant is adopted, the surface activity of the zwitterionic surfactant is fully utilized, crude oil in the oil-containing slurry is infiltrated, permeated and stripped, and the recovery rate of tertiary oil recovery is increased; the polyacrylamide binary composite composition for oil displacement, which is prepared by matching a zwitterionic surfactant with polyacrylamide and adding a functional aid polysiloxane and the like, has good high temperature resistance, salt tolerance, mineralization resistance and adsorption resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a polyacrylamide binary composite composition for oil displacement and a preparation method thereof. Background Art

[0002] As a new type of oil recovery technology, tertiary oil recovery technology can greatly improve the oil field recovery rate. The main agents of tertiary oil recovery oil recovery agents are generally polymers, surfactants and alkalis. The principle of polymer oil recovery is to improve the recovery rate of crude oil by increasing the sweep coefficient of water. Under certain conditions, the oil recovery effect of polymers mainly depends on the polymer properties. At present, partially hydrolyzed polyacrylamide has problems such as poor temperature resistance, poor salt resistance and poor solubility in application. Surfactants use their adsorption effect to change the wettability of the rock surface from oil wetting to water wetting, which is conducive to reducing the adhesion of crude oil on the rock surface and making it easy to peel off. Usually, ternary composite flooding (i.e., alkali-surfactant-polymer (ASP) composite) can increase the recovery rate by about 20% on the basis of water flooding. However, alkali reacts with some substances in rocks or formation water to generate insoluble substances, resulting in a series of side effects such as scaling and corrosion of pipelines and pumps, decreased formation permeability and destruction of porous media structure. Therefore, in recent years, alkali-free binary composite flooding has become one of the hot spots in the research of chemical flooding technology at home and abroad.

[0003] At present, the prior art has provided many surfactants that can be used for tertiary oil recovery, such as anionic surfactants, cationic surfactants, zwitterionic surfactants and nonionic surfactants, among which heavy alkylbenzene sulfonates and petroleum sulfonates are the most widely used anionic surfactants. However, under alkali-free conditions, due to the insufficient lipophilicity of conventional anionic surfactants such as petroleum sulfonates and heavy alkylbenzene sulfonates, the oil displacement capacity of the composite system is greatly reduced, or even basically ineffective.

[0004] Therefore, how to construct an efficient alkali-free binary composite oil displacement system becomes a difficulty of this technology. The present invention provides an oil displacement agent compounded with zwitterionic surfactant, polyacrylamide, polyether-modified polysiloxane and other additives, which has good high temperature resistance, salt resistance, mineralization resistance and adsorption resistance, and can achieve ultra-low interfacial tension without adding alkali. It is a chemical oil displacement agent for tertiary oil recovery worthy of promotion. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an alkali-free binary composite oil-displacing agent, which adopts anionic and cationic surfactants and polyacrylamide, and adds functional additives such as polysiloxane to obtain an oil-displacing agent with ultra-low interfacial tension, high temperature resistance and adsorption resistance.

[0006] A polyacrylamide binary composite composition for oil displacement comprises the following components, calculated by mass percentage: 0.5% to 2.0% polyacrylamide, 3.0% to 5.0% zwitterionic surfactant, 20% to 40% polysiloxane, 4.0% to 8.0% suspending agent, 5.0% to 10.0% penetrant, 1.0% to 2.0% high temperature stabilizer, and the balance is water.

[0007] Preferably, the polysiloxane is a polyether-modified polysiloxane that has been subjected to a hydrophobic high-temperature treatment after being polyether-modified; specifically, the polyether polysiloxane is added into a reaction kettle, hydrophobic silica is added, the temperature is raised to 130-150° C., stirred and refluxed for 2-4 hours, and cooled to obtain the polysiloxane.

[0008] Preferably, the chemical structural formula of the polyether polysiloxane is as follows: .

[0009] Preferably, the polyacrylamide is anionic, with a relative molecular weight of 1.0×10 7 ~2.0×10 7 .

[0010] Preferably, the zwitterionic surfactant is one or both of dodecyl sulfobetaine and cocamidopropyl betaine.

[0011] Preferably, the suspending agent is one or both of carboxymethyl cellulose and bentonite.

[0012] Preferably, the penetrant is propylene glycol.

[0013] Preferably, the high temperature stabilizer is thiourea.

[0014] A method for preparing a polyacrylamide binary composite composition for oil displacement comprises the following steps: adding polysiloxane and a penetrant into a reaction kettle and stirring for 1-2 hours; sequentially adding a zwitterionic surfactant, a suspending agent, polyacrylamide, and a high-temperature stabilizer into the reaction kettle, adding water, increasing the stirring speed of the reaction kettle to 800-1200 rpm, stirring for 30 minutes to 2 hours, and obtaining the polyacrylamide binary composite composition.

[0015] Beneficial effects of the present invention: (1) Using polysiloxane as the dispersion system, it can resist high temperatures and reduce surface tension; (2) Use zwitterionic surfactants to fully utilize their surface activity to infiltrate, penetrate, and strip the crude oil in the oil-containing mud, thereby improving the tertiary oil recovery rate; (3) The polyacrylamide binary composite for oil recovery prepared by combining anionic and cationic surfactants with polyacrylamide and adding functional additives such as polysiloxane has good high temperature resistance, salt resistance, mineralization resistance and adsorption resistance. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with embodiments. The preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0017] Example 1 A polyacrylamide binary composite composition for oil displacement, comprising the following components by mass percentage: 0.5% polyacrylamide, 4.0% zwitterionic surfactant, 30% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.0% high temperature stabilizer, and the balance is water; The polyacrylamide is anionic and has a relative molecular weight of 1.0×10 7 ; The zwitterionic surfactant is dodecyl sulfobetaine; The suspending agent is carboxymethyl cellulose; The penetrant is propylene glycol; The high temperature stabilizer is thiourea; The polysiloxane is a polyether-modified polysiloxane which has been subjected to a hydrophobic high temperature treatment and has a structural formula of The polyether polysiloxane is added into the reaction kettle, and hydrophobic silica is added, the temperature is raised to 130-150° C., stirred and refluxed for 2-4 hours, and then cooled to obtain.

[0018] A method for preparing a polyacrylamide binary composite composition for oil displacement comprises the following steps: adding polysiloxane and a penetrant into a reaction kettle and stirring for 1 hour; sequentially adding a zwitterionic surfactant, a suspending agent, polyacrylamide and a high-temperature stabilizer into the reaction kettle, adding water, increasing the stirring speed of the reaction kettle to 1000 rpm, stirring for 1 hour, and obtaining the polyacrylamide binary composite composition.

[0019] Example 2 A polyacrylamide binary composite composition for oil displacement includes the following components by mass percentage: 1% polyacrylamide, 3.0% zwitterionic surfactant, 30% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.0% high temperature stabilizer, and the balance is water. Other components are the same as those in Example 1.

[0020] Example 3 A polyacrylamide binary composite composition for oil displacement includes the following components by mass percentage: 1% polyacrylamide, 4.0% zwitterionic surfactant, 30% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.5% high temperature stabilizer, and the balance is water. Other components are the same as those in Example 1.

[0021] Example 4 A polyacrylamide binary composite composition for oil displacement includes the following components by mass percentage: 1.5% polyacrylamide, 3.0% zwitterionic surfactant, 30% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.5% high temperature stabilizer, and the balance is water. Other components are the same as those in Example 1.

[0022] Example 5 A polyacrylamide binary composite composition for oil displacement includes the following components by mass percentage: 1.8% polyacrylamide, 3.0% zwitterionic surfactant, 35% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.5% high temperature stabilizer, and the balance is water. Other components are the same as those in Example 1.

[0023] Example 6 A polyacrylamide binary composite composition for oil displacement includes the following components by mass percentage: 1.8% polyacrylamide, 4.0% zwitterionic surfactant, 35% polysiloxane, 6.0% suspending agent, 8.0% penetrant, 1.5% high temperature stabilizer, and the balance is water. Other components are the same as those in Example 1.

[0024] Example 7 A polyacrylamide binary composite composition for oil displacement, comprising the following components by mass percentage: 2% polyacrylamide, 5% zwitterionic surfactant, 40% polysiloxane, 8.0% suspending agent, 10.0% penetrant, 2.0% high temperature stabilizer, and the balance is water; The polyacrylamide is anionic and has a relative molecular weight of 2.0×10 7 ; The zwitterionic surfactant is obtained by mixing dodecyl sulfobetaine and cocamidopropyl betaine in a mass ratio of 2:1; The suspending agent is carboxymethyl cellulose; The rest is the same as in Example 1.

[0025] A method for preparing a polyacrylamide binary composite composition for oil displacement comprises the following steps: adding polysiloxane and a penetrant into a reaction kettle and stirring for 2 hours; sequentially adding a zwitterionic surfactant, a suspending agent, polyacrylamide, and a high-temperature stabilizer into the reaction kettle; adding water, raising the stirring speed of the reaction kettle to 1100 rpm, and stirring for 30 minutes to obtain the polyacrylamide binary composite composition.

[0026] Example 8 A polyacrylamide binary composite composition for oil displacement, comprising the following components by mass percentage: 1% polyacrylamide, 3% zwitterionic surfactant, 40% polysiloxane, 4.0% suspending agent, 5.0% penetrant, 1.0% high temperature stabilizer, and the balance is water; The zwitterionic surfactant is cocamidopropyl betaine; The suspending agent is obtained by mixing carboxymethyl cellulose and bentonite in a mass ratio of 1:1; The rest is the same as in Example 1.

[0027] A method for preparing a polyacrylamide binary composite composition for oil displacement comprises the following steps: adding polysiloxane and a penetrant into a reaction kettle and stirring for 2 hours; sequentially adding a zwitterionic surfactant, a suspending agent, polyacrylamide, and a high-temperature stabilizer into the reaction kettle; adding water, raising the stirring speed of the reaction kettle to 1100 rpm, and stirring for 30 minutes to obtain the polyacrylamide binary composite composition.

[0028] Comparative Example 1 The polysiloxane was replaced by polyether polysiloxane, and the rest was the same as in Example 1.

[0029] Performance Testing (1) Interfacial tension evaluation The interfacial tension between the above oil displacement composition and the crude oil of Qilicun Oil Production Plant of Yanchang Petroleum Group was measured by using JYW-200B / JYW-200C fully automatic interfacial tension meter at 80°C and a rotation speed of 4500 rpm. The results are shown in Table 1.

[0030] (2) Viscosity evaluation The apparent viscosity of the oil displacement composition was measured by DSF-3017 high temperature high shear viscosity tester at 80 °C and a shear rate of 7.34 s -1 The results are shown in Table 1.

[0031] (3) Oil displacement experiment evaluation According to the physical simulation oil displacement effect test of composite oil displacement system in SY / T6424-2000 composite oil displacement system performance test method, at 80℃, the length is 30cm, the diameter is 2.5cm, and the permeability is 1.5 m2 The simulated oil displacement experiment was carried out on the core of the rock. First, water was injected to drive the rock to a water content of 98%. After the water displacement, 0.3 pv (core pore volume) of the above oil displacement composition was injected, and then water was driven to a water content of 98%. The results of enhancing the oil recovery are shown in Table 1.

[0032] Table 1 Performance evaluation of oil displacement compositions of Examples 1-8 (4) Temperature resistance test According to the formation temperature of a high-temperature and high-salt oil reservoir in the west of China being about 110°C, the temperature of the oil displacement composition was raised to 110°C, the viscosity of the composition at this temperature was measured, and the temperature resistance of the composition was evaluated by the viscosity retention rate.

[0033] (5) Salt tolerance test Simulate the produced water from the oil production plant to prepare the brine solution, where Na ＋ 58500mg / LCa 2＋ 2440 mg / LMg 2＋ The concentration of the oil-displacing agent was 604 mg / L, 0.4% of the oil-displacing agent composition was added, and the mixture was stirred for 2 h. A blank experiment was performed to measure the viscosity of the solution and calculate the viscosity retention rate to judge the quality of the salt resistance.

[0034] (6) Anti-mineralization test Simulated formation water was prepared with deionized 2×10 4 mg / L Na + , 2×10 4 mg / L Ca 2+ Mg 2+ , add 0.2% of the oil-displacing agent composition, stir thoroughly for 2 h, and conduct a blank experiment to measure the viscosity of the solution and calculate the viscosity retention rate to judge the quality of the anti-mineralization performance.

[0035] Table 2 Performance evaluation of oil displacement composition of Example 1-8 2 In summary, the polyacrylamide binary composite composition provided by the present application can show a good ability to reduce the oil-water interfacial tension, can significantly improve the oil recovery rate, and can achieve ultra-low interfacial tension without the use of strong alkali. It also has good high temperature resistance, salt resistance, mineralization resistance and adsorption resistance.

[0036] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A polyacrylamide binary composite composition for oil displacement, characterized in that: Calculated by mass percentage, it includes the following components: polyacrylamide 0.5% to 2.0%, zwitterionic surfactant 3.0% to 5.0%, polysiloxane 20% to 40%, suspending agent 4.0% to 8.0%, penetrant 5.0% to 10.0%, high temperature stabilizer 1.0% to 2.0%, and the balance is water.

2. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The polysiloxane is a polyether-modified polysiloxane that has been subjected to a hydrophobic high-temperature treatment after being polyether-modified; specifically, the polyether polysiloxane is added into a reaction kettle, hydrophobic silica is added, the temperature is raised to 130-150° C., stirred and refluxed for 2-4 hours, and cooled to obtain the polysiloxane.

3. The polyacrylamide binary composite composition for oil displacement according to claim 2, characterized in that: The chemical structural formula of the polyether polysiloxane is as follows: 。 4. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The polyacrylamide is anionic and has a relative molecular weight of 1.0×10 7 ~2.0×10 7 .

5. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The zwitterionic surfactant is one or both of dodecyl sulfobetaine and cocamidopropyl betaine.

6. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The suspending agent is one or both of carboxymethyl cellulose and bentonite.

7. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The penetrant is propylene glycol.

8. The polyacrylamide binary composite composition for oil displacement according to claim 1, characterized in that: The high temperature stabilizer is thiourea.

9. A method for preparing the polyacrylamide binary composite composition for oil displacement according to claims 1-8, characterized in that: Specifically, polysiloxane and penetrant are added to the reactor and stirred for 1-2 hours; zwitterionic surfactant, suspending agent, polyacrylamide, and high-temperature stabilizer are added to the reactor in sequence, water is added, the stirring speed of the reactor is increased to 800-1200 rpm, and stirred for 30 minutes to 2 hours to obtain a polyacrylamide binary composite composition.

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