A graphene oxide composite oil displacement agent, its preparation method and application

Abstract

This invention provides a graphene oxide composite oil displacement agent, its preparation method, and its application. The graphene oxide composite oil displacement agent comprises poly-3-hydroxytyramine and graphene oxide, wherein the poly-3-hydroxytyramine and graphene oxide are chemically bonded. The preparation method includes mixing and reacting 3-hydroxytyramine hydrochloride with graphene oxide. The resulting composite oil displacement agent is applied to tertiary oil recovery. The composite oil displacement agent provided by this invention exhibits excellent hydrophilicity, acid and alkali resistance, and salt resistance. It can form stable water-in-oil emulsions with crude oil over a wide pH range or at high salinity, improving emulsion stability and viscosity. It has strong emulsifying properties, expanding the emulsion sweep volume, and has broad application prospects in low-to-medium permeability reservoirs. The preparation method provided by this invention is simple and highly practical.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, and relates to an oil displacement agent, particularly to a graphene oxide composite oil displacement agent and its preparation method and application. Background Technology

[0002] As oilfields gradually enter the high and ultra-high water-cut stages, maintaining stable production becomes increasingly difficult, making enhanced oil recovery an urgent need for oilfield development. Chemical flooding can significantly improve the viscous fingering and phase-separated flow of reservoir fluids and expand the flooding area, thereby increasing the recovery rate. However, oil well environments are complex, and traditional polymeric flooding agents generally have poor salt tolerance, causing their emulsification performance to deteriorate with changes in pH or salinity, thus reducing flooding efficiency. In contrast, nanoparticle flooding agents can avoid these problems. They irreversibly adsorb at the oil-water interface, forming a mechanically strong oil-water interface layer, thereby improving the stability of the emulsion under harsh environments such as high temperature, high pressure, high shear rate, and high salinity. Furthermore, compared with polymeric flooding agents, nanoparticles used in emulsion preparation have advantages such as lower dosage, less environmental pollution, and better emulsion stability.

[0003] CN106433593A discloses a method for preparing graphene nano-oil displacement agent. The method involves mixing graphene oxide with a polymer and a reducing agent, stirring until the mixture is homogeneous, and then cooling and drying to obtain the oil displacement agent. This oil displacement agent has temperature adaptability, and the hydrophilic graphene oxide can be transformed into hydrophobic graphene during the oil displacement process using the high temperature of the formation, thereby improving the oil displacement efficiency.

[0004] CN114058342A discloses a modified graphene oxide nanosheet thickener, an oil displacement polymer system, its application, and an oil reservoir displacement method. The thickener is graphene oxide nanosheets grafted with a small molecule surfactant. Combining this thickener with an oil displacement polymer system increases the viscosity of the polymer, improves thickening efficiency, and thus enhances oil recovery. The aforementioned two oil displacement agents require compounding with polymers, which affects the oil displacement efficiency, and compounding often results in poor emulsion stability.

[0005] CN115717064A discloses a graphene oxide-carbon nanotube composite oil displacement agent and its application. The composite oil displacement agent is a sheet-like-fiber composite structure formed by combining graphene oxide and carbon nanotubes. The main function of this composite oil displacement agent is to utilize its structural characteristics to reduce interfacial tension through adsorption, thereby increasing oil production. However, its emulsification ability for crude oil is very limited.

[0006] Therefore, to address the shortcomings of existing technologies, there is a need to provide a graphene oxide composite oil displacement agent, its preparation method, and its application. Summary of the Invention

[0007] The purpose of this invention is to provide a graphene oxide composite oil displacement agent, its preparation method and application, which can solve the problem of poor stability of single nanoparticles or nanoparticles and polymer composite oil displacement systems, and improve acid and alkali resistance and salt resistance, thereby increasing oil displacement efficiency.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a graphene oxide composite oil displacement agent, wherein the graphene oxide composite oil displacement agent comprises poly-3-hydroxytyramine and graphene oxide; wherein the poly-3-hydroxytyramine and graphene oxide are chemically bonded together.

[0010] The composite oil displacement agent provided by this invention synthesizes zero-dimensional poly-3-hydroxytyramine nanoparticles on the surface of graphene oxide nanosheets. The amino groups contained in 3-hydroxytyramine react with the carboxyl and epoxy groups on the surface of graphene oxide to form CN chemical bonds. Graphene oxide and crude oil are adsorbed at the oil-water interface through π-π interactions, forming a three-dimensional barrier at the oil-water interface, which hinders droplet aggregation. Through the synergistic effect of 3-hydroxytyramine and graphene oxide, the strength of the composite film at the oil-water interface is further increased, forming a stable water-in-oil emulsion with crude oil. This improves the emulsification ability and emulsion stability of the composite oil displacement agent, achieving efficient oil displacement and expanding the emulsion sweep.

[0011] In a second aspect, the present invention provides a method for preparing the graphene oxide composite oil displacement agent as described in the first aspect, the preparation method comprising the following steps:

[0012] The graphene oxide composite oil displacement agent is obtained by mixing and reacting 3-hydroxytyramine hydrochloride with graphene oxide.

[0013] The preparation method provided by this invention can controllably synthesize zero-dimensional poly-3-hydroxytyramine nanoparticles on the surface of graphene oxide. The method is simple and has strong applicability.

[0014] Preferably, the mass ratio of 3-hydroxytyramine hydrochloride to graphene oxide is 1:(0.2-5), for example, it can be 1:0.2, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1:(0.5-1.5).

[0015] Preferably, the pH of the reaction is 5-11, for example, it can be 5, 6, 7, 8, 9, 10 or 11, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 6-9.

[0016] Preferably, the reaction temperature is 10-75°C, for example, it can be 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 75°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the reaction time is 1-48h, for example, it can be 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h or 48h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 12-24h.

[0018] Preferably, solid-liquid separation and purification are performed sequentially after the reaction.

[0019] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0020] 3-hydroxytyramine hydrochloride and graphene oxide were mixed at a mass ratio of 1:(0.2-5) and reacted at pH 5-11 and temperature 10-75℃ for 1-48 hours. After solid-liquid separation and purification, the graphene oxide composite oil displacement agent was obtained.

[0021] Thirdly, the present invention provides an application of the graphene oxide composite oil displacement agent as described in the first aspect, wherein the graphene oxide composite oil displacement agent is applied to tertiary oil recovery.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The composite oil displacement agent provided by this invention has excellent hydrophilicity, acid and alkali resistance, and salt resistance. It can form a stable water-in-oil emulsion with crude oil in a wide pH range or at high salinity, which can improve the stability and viscosity of the emulsion. It has strong emulsification effect and can expand the emulsion sweep volume, and has broad application prospects in medium and low permeability reservoirs. The preparation method provided by this invention is simple and practical. Attached Figure Description

[0024] Figure 1 This is a transmission electron microscope image of the graphene oxide composite oil displacement agent provided in Example 1 of the present invention.

[0025] Figure 2 This is a transmission electron microscope image of the graphene oxide composite oil displacement agent provided in Example 1 of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0027] Example 1

[0028] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0029] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.1 g of graphene oxide. The mixture was reacted at 45 °C for 12 h, and the pH of the solution was controlled at 7.5 during the reaction. After the reaction was completed, solid-liquid separation was performed. The product was washed multiple times with water and ethanol to remove residual unreacted components, and then freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0030] The transmission electron microscope (TEM) image of the graphene oxide composite oil displacement agent prepared in this embodiment is shown below. Figure 1 and Figure 2 As shown in the figure, the oil displacement agent prepared by this invention is a sheet-like nanomaterial.

[0031] The graphene oxide composite oil displacement agent prepared in this embodiment was formulated into a dispersion using formation water. The concentration of the oil displacement agent in the dispersion was 0.009 wt%. The dispersion was mixed with Xinjiang crude oil at a certain liquid-to-oil volume ratio. The Xinjiang crude oil had a pH of 7.8 and a salinity of 9993 ppm. The liquid-to-oil volume ratios were 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1. The mixture was kept at 78°C for 1 hour, and then dispersed using an IKA homogenizer for 1 minute. The oil-water emulsification and emulsion stability were observed. At liquid-to-oil volume ratios below 7:3, the oil and water could emulsify to form a stable water-in-oil emulsion. The results are listed in Table 1.

[0032] Example 2

[0033] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0034] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.1 g of graphene oxide. The mixture was reacted at 75 °C for 12 h, with the pH of the solution controlled at 7.5 during the reaction. After the reaction was completed, solid-liquid separation was performed. The product was washed multiple times with water and ethanol to remove residual unreacted components, and then freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0035] The graphene oxide composite oil displacement agent prepared in this embodiment was formulated into a dispersion using formation water. The concentration of the oil displacement agent in the dispersion was 0.005 wt%. The dispersion was mixed with Changqing crude oil at a certain liquid-to-oil volume ratio. The pH of Changqing crude oil was 7.3, and the salinity was 32000 ppm. The liquid-to-oil volume ratios were 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1. The mixture was kept at 55°C for 1 hour, and then dispersed using an IKA homogenizer for 1 minute. The oil-water emulsification and emulsion stability were observed. At liquid-to-oil volume ratios below 7:3, the oil and water could emulsify to form a stable water-in-oil emulsion. The results are listed in Table 1.

[0036] Example 3

[0037] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0038] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.1 g of graphene oxide. The mixture was reacted at 75 °C for 24 h, and the pH of the solution was controlled at 7.5 during the reaction. After the reaction was completed, solid-liquid separation was performed. The product was washed multiple times with water and ethanol to remove residual unreacted components, and then freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0039] The graphene oxide composite oil displacement agent prepared in this embodiment was formulated into a dispersion using formation water. The concentration of the oil displacement agent in the dispersion was 0.015 wt%. The dispersion was mixed with Jilin crude oil at a certain liquid-to-oil volume ratio. The Jilin crude oil had a pH of 7.1 and a salinity of 6631 ppm. The liquid-to-oil volume ratios were 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1. The mixture was kept at 55°C for 1 hour, and then dispersed using an IKA homogenizer for 1 minute. The oil-water emulsification and emulsion stability were observed. At liquid-to-oil volume ratios below 8:2, the oil and water could emulsify to form a stable water-in-oil emulsion, with a maximum water content of 80%. The results are listed in Table 1.

[0040] Table 1

[0041] Liquid-to-oil volume ratio Example 1 Example 2 Example 3 1:9 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 2:8 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 3:7 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 4:6 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 5:5 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 6:4 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 7:3 Phase Indistinguishable Phase Indistinguishable Phase Indistinguishable 8:2 Phase separation Phase separation Phase Indistinguishable 9:1 Phase separation Phase separation Phase separation

[0042] Example 4

[0043] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0044] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.5 g of graphene oxide. The mixture was reacted at 45 °C for 20 h, with the pH of the solution controlled at 7 during the reaction. After the reaction was completed, solid-liquid separation was performed, and the product was washed multiple times with water and ethanol to remove residual unreacted components. Then, it was freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0045] Example 5

[0046] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0047] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.25 g of graphene oxide. The mixture was reacted at 45 °C for 20 h, with the pH of the solution controlled at 6 during the reaction. After the reaction was completed, solid-liquid separation was performed, and the product was washed multiple times with water and ethanol to remove residual unreacted components. Then, it was freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0048] Example 6

[0049] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0050] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.75 g of graphene oxide. The mixture was reacted at 45 °C for 20 h, with the pH of the solution controlled at 9 during the reaction. After the reaction was completed, solid-liquid separation was performed, and the product was washed multiple times with water and ethanol to remove residual unreacted components. Then, it was freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0051] Example 7

[0052] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0053] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 2.5 g of graphene oxide. The mixture was reacted at 10 °C for 48 h, with the pH of the solution controlled at 11 during the reaction. After the reaction was completed, solid-liquid separation was performed. The product was washed multiple times with water and ethanol to remove residual unreacted components, and then freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0054] Example 8

[0055] This embodiment provides a graphene oxide composite oil displacement agent, the preparation method of which includes the following steps:

[0056] 0.5 g of 3-hydroxytyramine hydrochloride was dissolved in 100 mL of water, and then mixed with 100 mL of aqueous solution containing 0.1 g of graphene oxide. The mixture was reacted at 75 °C for 1 h, with the pH of the solution controlled at 5 during the reaction. After the reaction was completed, solid-liquid separation was performed. The product was washed multiple times with water and ethanol to remove residual unreacted components, and then freeze-dried to obtain the graphene oxide composite oil displacement agent.

[0057] Example 9

[0058] This embodiment provides a graphene oxide composite oil displacement agent. Compared with Example 4, the pH during the reaction is controlled at 4, and all other aspects are the same as in Example 4.

[0059] Example 10

[0060] This embodiment provides a graphene oxide composite oil displacement agent. Compared with Example 4, the pH during the reaction is controlled at 12, and all other parameters are the same as in Example 4.

[0061] Example 11

[0062] This embodiment provides a graphene oxide composite oil displacement agent. Compared with Example 4, the reaction temperature is controlled at 5°C, and all other aspects are the same as in Example 1.

[0063] Example 12

[0064] This embodiment provides a graphene oxide composite oil displacement agent. Compared with Example 4, the reaction temperature is controlled at 80°C, and the rest is the same as Example 1.

[0065] Comparative Example 1

[0066] This comparative example provides a graphene oxide oil displacement agent, wherein the graphene oxide oil displacement agent comprises graphene oxide.

[0067] The graphene oxide composite oil displacement agents prepared in Examples 4-12 and Comparative Example 1 were formulated into dispersions using formation water. The concentration of the oil displacement agent in the dispersions was 0.005 wt%. The dispersions were mixed with Changqing crude oil at specific liquid-to-oil volume ratios. The pH of the Changqing crude oil was 7.3, and its salinity was 32,000 ppm. The liquid-to-oil volume ratios were 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1, respectively. The mixtures were kept at 55°C for 1 hour, and then dispersed using an IKA homogenizer for 1 minute. The oil-water emulsification and emulsion stability were observed. The results are listed in Table 2.

[0068] Table 2

[0069] Maximum liquid-to-oil volume ratio of emulsion Phase splitting Example 4 7:3 Phase Indistinguishable Example 5 7:3 Phase Indistinguishable Example 6 7:3 Phase Indistinguishable Example 7 6:4 Phase Indistinguishable Example 8 6:4 Phase Indistinguishable Example 9 5:5 Phase Indistinguishable Example 10 5:5 Phase Indistinguishable Example 11 5:5 Phase Indistinguishable Example 12 5:5 Phase Indistinguishable Comparative Example 1 4:6 Phase Indistinguishable

[0070] As can be seen from Tables 1 and 2, the composite oil displacement agent provided in Examples 1-8 of this invention can emulsify crude oil with high salinity. Generally, forming a water-in-oil emulsion requires more oil than water, i.e., a liquid-to-oil volume ratio of less than 5:5, usually below 3:7. However, the composite oil displacement agent provided by this invention can increase the liquid-to-oil volume ratio of the emulsion to 6:4, and especially to 7:3. It has strong emulsification ability, requires low concentration and small dosage of oil displacement agent, and can form a stable water-in-oil emulsion with high oil displacement efficiency. Compared with Example 1, in Examples 9-12, the reaction pH and temperature, which are not preferred by this invention, are used, which reduces the reaction effect of 3-hydroxytyramine hydrochloride and graphene oxide, resulting in a decrease in the emulsification effect of the obtained composite oil displacement agent. In Comparative Example 1, only graphene oxide is used as the oil displacement agent, and its liquid-to-oil volume ratio during emulsification is only 4:6, with low emulsification ability.

[0071] In summary, the composite oil displacement agent provided by this invention has excellent hydrophilicity, acid and alkali resistance, and salt resistance. It can form stable water-in-oil emulsions with crude oil in a wide pH range or at high salinity, which can improve the stability and viscosity of the emulsion. It has strong emulsification effect and can expand the emulsion sweep volume, and has broad application prospects in medium and low permeability reservoirs. The preparation method provided by this invention is simple and highly practical.

[0072] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A graphene oxide composite oil displacement agent, characterized in that, The graphene oxide composite oil displacement agent comprises poly-3-hydroxytyramine and graphene oxide; the poly-3-hydroxytyramine and graphene oxide are chemically bonded together. The graphene oxide composite oil displacement agent is prepared by the following method: 3-hydroxytyramine hydrochloride was mixed with graphene oxide and reacted at pH 5-11 and temperature 10-75℃. Solid-liquid separation and purification were carried out sequentially to obtain the graphene oxide composite oil displacement agent. The mass ratio of 3-hydroxytyramine hydrochloride to graphene oxide is 1:(0.2-5).

2. A method for preparing the graphene oxide composite oil displacement agent as described in claim 1, characterized in that, The preparation method includes the following steps: 3-hydroxytyramine hydrochloride was mixed with graphene oxide and reacted at pH 5-11 and temperature 10-75℃. Solid-liquid separation and purification were carried out sequentially to obtain the graphene oxide composite oil displacement agent. The mass ratio of 3-hydroxytyramine hydrochloride to graphene oxide is 1:(0.2-5).

3. The preparation method according to claim 2, characterized in that, The mass ratio of 3-hydroxytyramine hydrochloride to graphene oxide is 1:(0.5-1.5).

4. The preparation method according to claim 2, characterized in that, The pH of the reaction is 6-9.

5. The preparation method according to claim 2, characterized in that, The reaction time is 1-48 hours.

6. The preparation method according to claim 5, characterized in that, The reaction time is 12-24 hours.

7. The application of the graphene oxide composite oil displacement agent as described in claim 1, characterized in that, The graphene oxide composite oil displacement agent is used for tertiary oil recovery.

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