Magnetic response intelligent nanometer oil displacement liquid and preparation method thereof

Abstract

The invention discloses a magnetic response intelligent nanometer oil displacement liquid and a preparation method thereof, and the oil displacement liquid comprises the following components in percentage by mass: 1.0%-3.0% of a surfactant, 2.0%-5.0% of nanometer silicon dioxide, 0.5%-2.5% of magnetic nanoparticles, 2.0%-4.0% of an alkaline substance, 0.5%-2.0% of a polymer and the balance of water. Efficient displacement can be achieved, the recovery efficiency can be improved, the oil displacement liquid is easy to prepare, large-scale production is easy to achieve, and the oil displacement cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield exploitation, and in particular to a magnetic response intelligent nano oil displacement fluid and a preparation method thereof. Background Art

[0002] As the oil field enters the middle and late stages of development, the phenomenon of declining production capacity and low water injection qualification rate is becoming increasingly serious. Due to the low sweep efficiency of secondary oil recovery technology, coupled with a series of problems such as strong heterogeneity and prominent interlayer contradictions in the late stage of development, it is difficult to achieve stable production and increase of crude oil. Tertiary oil recovery uses chemical flooding to achieve crude oil displacement, which effectively solves the technical bottleneck of secondary oil recovery. After years of development, the technology has gradually matured. However, as the oil field gradually transforms from conventional oil reservoirs to low-permeability oil reservoirs, tertiary oil recovery also faces technical bottlenecks such as high energy consumption, high cost, and low recovery degree. It is urgent to explore new oil recovery technologies to meet the needs of field applications.

[0003] In order to solve the various problems caused by various chemical oil-displacing agents, researchers have proposed nanochemical oil-displacing agents. Nanochemical oil-displacing agents have a large specific surface area and surface energy, which can significantly reduce the oil-water interfacial tension and increase the contact angle between oil and rock formations, making it easier for crude oil to peel off from the rock formations, significantly improving the oil recovery rate. Although nano oil-displacing agents have advantages over conventional oil-displacing agents in terms of changing the wettability of rock formations, they still have the following disadvantages: (1) Nanofluids with water as a dispersant, the nanoparticles in them are easy to agglomerate into large particles due to their high specific surface energy, making it difficult to control the particle size of the nanoparticles; (2) The hydrophilic and lipophilic properties of nanoparticles are difficult to control, making it difficult to improve the sweep coefficient and oil washing efficiency of nano oil-displacing agents in oil reservoirs, which is unfavorable to the driving efficiency of crude oil and the replacement efficiency of displacement fluids. Summary of the invention

[0004] The main purpose of the present invention is to provide a magnetically responsive intelligent nano oil-displacing fluid and a preparation method thereof, so as to solve the technical problem that the oil-displacing effect of the oil-displacing agent in the prior art is poor.

[0005] According to one aspect of the present invention, a magnetically responsive intelligent nano oil-displacing fluid is provided. The oil-displacing fluid comprises, by mass percentage, 1.0 to 3.0% of a surfactant, 2.0 to 5.0% of nano-silicon dioxide, 0.5 to 2.5% of magnetic nanoparticles, 2.0 to 4.0% of an alkaline substance, and 0.5 to 2.0% of a polymer, with the remainder being water.

[0006] According to one embodiment of the present invention, the surfactant is dodecyl phosphate monoester or polyoxyethylene lauryl alcohol ether hydroquinone ether.

[0007] According to one embodiment of the present invention, the particle size of the nano-silicon dioxide is 30-100 nm.

[0008] According to one embodiment of the present invention, the magnetic nanoparticles are nano-Fe3O4 and / or nano-γ-Fe2O3.

[0009] According to an embodiment of the present invention, the particle size of the magnetic nanoparticles is 10-100 nm.

[0010] According to one embodiment of the present invention, the alkaline substance is sodium hydroxide or sodium carbonate.

[0011] According to one embodiment of the present invention, the polymer is partially hydrolyzed polyacrylamide.

[0012] According to another aspect of the present invention, a method for preparing a magnetically responsive intelligent nano oil displacement fluid is provided, comprising:

[0013] Mixing a surfactant and nano-silicon dioxide and adding the mixture to an alkaline solution to obtain a first mixture;

[0014] adding a polymer to the first mixture to obtain a second mixture;

[0015] The second mixture is compounded with the magnetic nanoparticle material and stirred to obtain the oil displacement fluid.

[0016] According to one embodiment of the present invention, the mass of the surfactant accounts for 1.0-3.0% of the total mass of the oil-displacing fluid; the mass of the nano-silicon dioxide accounts for 2.0-5.0% of the total mass of the oil-displacing fluid; the mass of the magnetic nano-particle material accounts for 0.5-2.5% of the total mass of the oil-displacing fluid; the alkaline substance in the alkaline solution accounts for 2.0-4.0% of the total mass of the oil-displacing fluid, and the mass of the polymer accounts for 0.5-2.0% of the total mass of the oil-displacing fluid.

[0017] According to one embodiment of the present invention, the surfactant is dodecyl phosphate monoester or polyoxyethylene lauryl alcohol ether hydroquinone ether.

[0018] Through the technical solution of the present invention, the oil displacement process can be intelligently controlled based on the magnetic field, the swept volume and sweep coefficient can be effectively increased, and the oil-water interfacial tension can be reduced, ultimately achieving efficient displacement and improving the recovery rate. In addition, the preparation conditions of the oil displacement fluid are mild, the technical route is simple, and it is easy to achieve large-scale production and significantly reduce the cost of oil displacement. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments.

[0020] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0021] The inventors of the present application recognize that smart nanochemical oil displacement agents can improve oil recovery and achieve smart oil displacement, that is, respond to temperature, magnetic field or pH, change hydrophilicity and particle size, increase displacement fluid viscosity or change other properties.

[0022] Based on this understanding, the present invention proposes a magnetically responsive intelligent nano oil-displacing fluid, which comprises, by mass percentage, 1.0-3.0% of a surfactant, 2.0-5.0% of nano-silicon dioxide, 0.5-2.5% of magnetic nanoparticles, 2.0-4.0% of an alkaline substance, and 0.5-2.0% of a polymer, with the remainder being water.

[0023] The oil displacement fluid of the present invention has low concentration and low injection pump pressure requirement. After being injected into the formation, the flow direction, range and contact time of the nanofluid can be controlled by adding a magnetic field, thereby realizing intelligent operation and directional control, effectively increasing the swept volume, and thus realizing efficient displacement and improving the recovery rate. The preparation conditions of the magnetically responsive intelligent nano oil displacement fluid of the present invention are mild, the technical route is simple, and it is easy to realize large-scale production, and the oil displacement cost is significantly reduced.

[0024] The effects of the various components in the oil displacement fluid of the present invention are described below:

[0025] The introduction of magnetic nanoparticles makes it possible to control the flow range of the oil displacement fluid through an external electric field, control the contact time between the nanofluid and the reservoir, and realize intelligent operation, thereby displacing crude oil in small pores, expanding the swept volume, and improving the recovery rate; increasing the viscosity of the displacement fluid and reducing the mobility ratio.

[0026] Surfactants can reduce the interfacial tension between oil and water, thereby recovering the oil that is adhered to the rock surface and adsorbed in the pore throats of the core and is difficult to flow.

[0027] Nano-silica has strong hydrophobic and lipophilic properties as well as a large specific surface area and surface energy, which can reduce the oil-water interfacial tension and make crude oil easily displaced.

[0028] Polymers can increase the plane sweep coefficient and longitudinal sweep coefficient of injected water by increasing the viscosity of the water phase and reducing the water velocity ratio, thereby improving oil recovery.

[0029] The addition of alkaline substances can reduce the oil-water interfacial tension and act as a sacrificial agent to reduce the adsorption of nanomaterials in the formation. In addition, it can react with formation crude oil to produce surface activity and improve oil recovery efficiency.

[0030] If the content of the above components is too high or too low, it will lead to the inability to form ultra-low interfacial tension and the inability to expand the swept volume, making it impossible to improve the recovery rate.

[0031] In some embodiments, the surfactant is an anionic surfactant or a nonionic surfactant. In some embodiments, the surfactant is dodecyl phosphate monoester or polyoxyethylene dodecyl alcohol ether hydroquinone ether. Compared with other surfactants, the surfactant can significantly reduce the oil-water interfacial tension, thereby recovering the oil that is adhered to the rock surface and adsorbed in the core pore throat and is not easy to flow.

[0032] In some embodiments, the particle size of the nano-silica is 30 to 100 nm.

[0033] In some embodiments, the magnetic nanoparticles are nano-Fe3O4 and / or nano-γ-Fe2O3.

[0034] In some embodiments, the particle size of the magnetic nanoparticles is 10-100 nm.

[0035] In some embodiments, the alkaline substance is sodium hydroxide or sodium carbonate.

[0036] In some embodiments, the polymer is partially hydrolyzed polyacrylamide. The polymer can increase the plane sweep coefficient and the longitudinal sweep coefficient of the injected water by increasing the viscosity of the water phase and reducing the water velocity ratio, thereby improving the oil recovery rate.

[0037] The present invention also provides a method for preparing a magnetically responsive intelligent nano oil-displacing fluid, comprising:

[0038] Mixing a surfactant and nano-silicon dioxide and adding the mixture to an alkaline solution to obtain a first mixture;

[0039] adding a polymer to the first mixture to obtain a second mixture;

[0040] The second mixture is compounded with the magnetic nanoparticle material and stirred to obtain the oil displacement fluid.

[0041] The preparation method is simple to operate and can be carried out at room temperature. By adding magnetic nanoparticles in the last step, it is ensured that the magnetic material produces a good magnetic response effect.

[0042] In some embodiments, the mass of the surfactant accounts for 1.0-3.0% of the total mass of the oil-displacing fluid; the mass of the nano-silicon dioxide accounts for 2.0-5.0% of the total mass of the oil-displacing fluid; the mass of the magnetic nanoparticle material accounts for 0.5-2.5% of the total mass of the oil-displacing fluid; the alkaline substance in the alkaline solution accounts for 2.0-4.0% of the total mass of the oil-displacing fluid, and the mass of the polymer accounts for 0.5-2.0% of the total mass of the oil-displacing fluid.

[0043] In some embodiments, the surfactant is dodecyl phosphate monoester or polyoxyethylene lauryl alcohol ether hydroquinone ether.

[0044] In summary, the present invention uses surfactants and nano-silicon dioxide as core reagents, and compounding magnetic nanoparticles with the core reagents to form a magnetically responsive intelligent nano-chemical oil-displacing agent. The nano-oil-displacing fluid obtained by the present invention has mild preparation conditions, a simple technical route, and is easy to achieve large-scale production. It can be used as a crude oil displacement fluid to improve the recovery rate of crude oil, and the magnetic nano-oil-displacing agent has a good magnetic aggregation effect, which can improve the oil displacement efficiency in a directionally manner.

[0045] The following is a description based on specific embodiments.

[0046] Example 1

[0047] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage, 2.0% of dodecyl phosphate monoester, 2.5% of nano-SiO2, 1.0% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0048] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0049] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 82.3%, and the oil displacement efficiency was increased by 10.2% after water flooding.

[0050] Example 2

[0051] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage, 2.0% of dodecyl phosphate monoester, 2.5% of nano-SiO2, 2.0% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0052] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0053] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 86.5%, and the oil displacement efficiency was increased by 13.2% after water flooding.

[0054] Example 3

[0055] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage, 2.0% of dodecyl phosphate monoester, 2.5% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0056] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0057] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 88.7%, and the oil displacement efficiency was increased by 14.8% after water flooding.

[0058] Example 4

[0059] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage, 2.0% of dodecyl phosphate monoester, 4.0% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0060] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0061] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 90.3%, and the oil displacement efficiency was increased by 16.2% after water flooding.

[0062] Example 5

[0063] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage, 2.0% of dodecyl phosphate monoester, 5.0% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0064] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0065] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 91.8%, and the oil displacement efficiency was increased by 18.3% after water flooding.

[0066] Example 6

[0067] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage: 2.0% of polyoxyethylene lauryl alcohol ether hydroquinone ether, 2.5% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0068] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0069] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 76.7%, and the oil displacement efficiency was increased by 9.3% after water flooding.

[0070] Example 7

[0071] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage: 2.0% of polyoxyethylene lauryl alcohol ether hydroquinone ether, 3.5% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium hydroxide and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0072] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added into sodium hydroxide solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The addition amount of each component is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0073] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 85.1%, and the oil displacement efficiency was increased by 10.6% after water flooding.

[0074] Example 8

[0075] The magnetic intelligent nano oil-displacing fluid of this embodiment comprises, by mass percentage: 2.0% of polyoxyethylene lauryl alcohol ether hydroquinone ether, 3.5% of nano-SiO2, 2.5% of Fe3O4 nanoparticles, 2.0% of sodium carbonate and 0.5% of partially hydrolyzed polyacrylamide, with the remainder being water; wherein the particle size of nano-SiO2 is 50nm, and the particle size of Fe3O4 nanoparticles is 100nm.

[0076] The preparation method of the magnetic intelligent nano oil-displacing liquid of the present embodiment is as follows: dodecyl phosphate monoester and nano-SiO2 material are fully mixed, added to sodium carbonate solution, partially hydrolyzed polyacrylamide is added, and then compounded with Fe3O4 nanoparticle material, stirred evenly, and the finished magnetic intelligent nano oil-displacing liquid is obtained. The amount of each component added is determined according to the respective content in the magnetic intelligent nano oil-displacing liquid.

[0077] In an artificial core displacement experiment in the laboratory of the Engineering Technology Research Center of Tongji University, the oil displacement efficiency of the nano oil displacement fluid of this embodiment reached 83.3%, and the oil displacement efficiency was increased by 9.9% after water flooding.

[0078] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A magnetically responsive intelligent nano oil displacement fluid, characterized in that: The oil displacement fluid comprises, by mass percentage, 1.0-3.0% of a surfactant, 2.0-5.0% of nano-silicon dioxide, 0.5-2.5% of magnetic nanoparticles, 2.0-4.0% of an alkaline substance, 0.5-2.0% of a polymer, and the remainder is water.

2. The oil displacement fluid according to claim 1, characterized in that: The surfactant is dodecyl phosphate monoester or polyoxyethylene lauryl alcohol ether hydroquinone ether.

3. The oil displacement fluid according to claim 1, characterized in that: The particle size of the nano silicon dioxide is 30-100 nm.

4. The oil displacement fluid according to claim 1, characterized in that: The magnetic nanoparticles are nano-Fe3O4 and / or nano-γ-Fe2O3.

5. The oil displacement fluid according to claim 1, characterized in that: The particle size of the magnetic nanoparticles is 10-100 nm.

6. The oil displacement fluid according to claim 1, characterized in that: The alkaline substance is sodium hydroxide or sodium carbonate.

7. The oil displacement fluid according to claim 1, characterized in that: The polymer is partially hydrolyzed polyacrylamide.

8. A method for preparing a magnetically responsive intelligent nano oil-displacing fluid, characterized in that: include: Mixing a surfactant and nano-silicon dioxide and adding the mixture to an alkaline solution to obtain a first mixture; adding a polymer to the first mixture to obtain a second mixture; The second mixture is compounded with the magnetic nanoparticle material and stirred to obtain the oil displacement fluid.

9. The method according to claim 8, characterized in that The mass of the surfactant accounts for 1.0-3.0% of the total mass of the oil displacement fluid; the mass of the nano-silicon dioxide accounts for 2.0-5.0% of the total mass of the oil displacement fluid; the mass of the magnetic nano-particle material accounts for 0.5-2.5% of the total mass of the oil displacement fluid; the alkaline substance in the alkaline solution accounts for 2.0-4.0% of the total mass of the oil displacement fluid, and the mass of the polymer accounts for 0.5-2.0% of the total mass of the oil displacement fluid.

10. The method according to claim 8, characterized in that The surfactant is dodecyl phosphate monoester or polyoxyethylene lauryl alcohol ether hydroquinone ether.