A nano-imbibition oil displacement agent, a preparation method and application thereof

Abstract

The application discloses a kind of nano imbibition oil displacement agents and preparation method and application thereof.The preparation method of the nano imbibition oil displacement agent includes the following steps: citric acid, glucose, long-chain amine, surfactant, organic solvent, short-chain alcohol and water are reacted at 140-200 DEG C and 0.4-0.5 MPa for 6-16 hours, to obtain the nano imbibition oil displacement agent.The method is simple and convenient, environmentally friendly, low in cost, and the nano imbibition oil displacement agent prepared has good surface interfacial activity under high temperature and high salt, can be used as an agent for imbibition oil production in ultra-low permeability reservoirs, and significantly improves the oil recovery.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical technology, specifically relating to a nano-permeation displacement agent, its preparation method, and its application. Background Technology

[0002] With the deepening of oil exploration and development, the proportion of low-permeability oil resources is increasing, especially in recent years, my country has discovered particularly abundant reserves of ultra-low permeability oil reservoirs. Therefore, the efficient development of ultra-low permeability oil reservoirs is an important direction for the development of my country's petroleum industry. Ultra-low permeability oil reservoirs have well-developed nanopores and high capillary forces, making full use of percolation and displacement mechanisms one of the effective ways to develop them efficiently. Percolation is related to the properties of the rock itself (permeability, porosity, wettability, etc.) and the properties of the fluid (oil-water viscosity ratio, oil-water interfacial tension, pH value, salinity, etc.), temperature, pressure, etc. Among these, wettability is one of the important factors affecting percolation. Generally, the more hydrophilic the rock pore walls, the better the percolation effect. At the same time, reducing the viscosity of crude oil can also effectively improve the percolation effect. In addition, there is an optimal range of oil-water interfacial tension for percolation under different permeabilities. Surfactants can change the wettability of rocks and reduce the oil-water interfacial tension and crude oil viscosity. Therefore, surfactants can improve oil recovery by enhancing percolation, as confirmed in field trials, but surfactants have limited effect on rock wettability.

[0003] Wasan et al. investigated the spreading behavior of nanoparticle suspensions (nanofluids) on solid surfaces and, for the first time, proposed that nanoparticles can form solid-like ordered structures in confined three-phase (solid-oil-water) contact zones. This structuring phenomenon of nanoparticles generates separation pressure in wedge-shaped films, thereby promoting the spreading of nanofluids on solid surfaces. Therefore, nanofluids can be used for soil remediation, oil spill removal, lubrication, and enhanced oil recovery. According to classical wetting theory, a solid surface can only be completely wetted by a liquid when the contact angle is zero. However, they found that by controlling the nanofluid concentration, nanoparticle size, and interfacial tension, the spontaneous spreading of nanofluids driven by structural separation pressure on solid surfaces can be achieved even when the contact angle is not zero. When the contact angle is large, smaller nanoparticles are more likely to form layered structures, thereby enhancing the spontaneous spreading of nanofluids driven by structural separation pressure on solid surfaces. This suggests that the spontaneous spreading of nanofluids on solid surfaces with relatively low hydrophilicity can be achieved by reducing the size of the nanoparticles. Therefore, enhancing rock wettability through nanofluids to effectively improve the oil recovery efficiency of ultra-low permeability reservoirs is a current research hotspot. Long Xueli et al. constructed a nanofluidic permeabilizer using amphiphilic grafted modified nano-silica particles, betaine-type surfactants, and nonionic surfactants (CN 113717709B). Luo Mingliang et al. prepared a nanomagnetic fluid fracturing fluid permeabilization system suitable for tight reservoirs using oleic acid-modified magnetic iron oxide nanoparticles (CN110454132B). Wu Wenwei et al. polymerized a temperature- and salt-resistant nano-permeabilizing oil displacement agent and its preparation method and application by polymerizing raw materials containing double-bond modified layered nanomaterials, hydrophilic monomers, and hydrophobic monomers (CN 114410286A). Jiang Lihua et al. prepared a temperature-resistant and salt-resistant nano-permeation and displacement agent for oil displacement in low-permeability reservoirs using nano-surfactants, nonionic surfactants, amphoteric surfactants and low-carbon alcohols, wherein the size of the nano-surfactants is less than 200 nm (CN114774096B).

[0004] While the aforementioned nanomaterials have achieved some success in improving oil recovery, their large size, lack of amphiphilicity, and poor interfacial activity make them unsuitable for the nanoscale pore throats of low-permeability reservoirs. Therefore, this invention proposes a nanomaterial for permeation-induced oil displacement based on ultra-small size and high interfacial activity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a nano-permeation displacement agent, its preparation method, and its application, thereby solving the problem that existing nano-displacement materials cannot meet the needs of low-permeability reservoir development.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On the one hand, the present invention provides a method for preparing a nano-permeable oil displacement agent, comprising the following steps: reacting citric acid, glucose, long-chain amine, surfactant, organic solvent, short-chain alcohol and water at 140~200 °C and 0.4~0.5 MPa for 6~16 hours to obtain the nano-permeable oil displacement agent.

[0008] Preferably, by mass percentage, the amount of citric acid is 0.5%~2%, the amount of glucose is 0.5%~4%, the amount of long-chain amine is 0.25%~2%, the amount of surfactant is 5%~8%, the amount of organic solvent is 3%~6%, the amount of short-chain alcohol is 10~15%, and the balance is water.

[0009] Preferably, the long-chain amine is a C8-C16 alkylamine, for example, it can be octylamine, decylamine, dodecylamine, tetradecylamine or hexadecylamine.

[0010] Preferably, the surfactant is betaine surfactant.

[0011] Preferably, the betaine surfactant includes one or more of lauramidopropyl betaine, cocamidopropyl betaine, oleamidopropyl betaine, lauramidopropyl hydroxysulfonate betaine, cocamidopropyl hydroxysulfonate betaine, and oleamidopropyl hydroxysulfonate betaine.

[0012] Preferably, the organic solvent is one or more of xylene, toluene, and limonene.

[0013] Preferably, the short-chain alcohol is a C2-C6 alcohol.

[0014] Preferably, the short-chain alcohol is one or more of ethanol, isopropanol, n-propanol, ethylene glycol, and propylene glycol.

[0015] In a second aspect, the present invention provides a nano-permeation displacement agent, which is prepared by the preparation method described in the first aspect.

[0016] Thirdly, the present invention also provides the application of a nano-permeation displacement agent prepared by the preparation method described in the first aspect in oil displacement in low-permeability reservoirs.

[0017] The beneficial effects of this invention are:

[0018] This invention uses citric acid, glucose, long-chain amines, surfactants, organic solvents, and short-chain alcohols as raw materials, reacting them under specific temperature and pressure conditions to obtain a nano-percolation displacement agent. Citric acid, glucose, and long-chain amines form amphiphilic carbon nanoparticles with hydrophilic groups and hydrophobic alkyl chains on their surface. These ultra-small amphiphilic carbon nanoparticles can significantly improve percolation displacement efficiency by altering the wettability of rock surfaces and reducing oil-water interfacial tension. Simultaneously, the formed amphiphilic carbon nanoparticles, surfactants, organic solvents, and short-chain alcohols form a synergistically stable nanoemulsion. The surfactants alter the wettability of the rock, the organic solvents enhance the solubilization effect of the displacement agent, and the short-chain alcohols reduce interfacial tension while also increasing the oil-washing capacity of the nanoemulsion.

[0019] The preparation method of this invention is simple, convenient, environmentally friendly, and low in cost. The prepared nano-permeation oil displacement agent has good surface and interfacial activity under high temperature and high salinity conditions, and can be used as a permeation oil recovery agent for ultra-low permeability reservoirs, significantly improving crude oil recovery rate. Attached Figure Description

[0020] Figure 1 The seepage recovery curves are for Examples 1-2 and Comparative Examples 1-2. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] All raw materials used in the following examples are commercially available products.

[0023] Example 1

[0024] 1g citric acid, 2g glucose, 1g hexadecylamine, 6g lauramide propyl betaine, 4g xylene, 12g ethylene glycol and 74g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 140 ℃ and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0025] Example 2

[0026] 1g citric acid, 3g glucose, 2g dodecylamine, 7g cocamidopropyl betaine, 5g limonene, 14g isopropanol and 68g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 180 ℃ and 0.4 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0027] Example 3

[0028] 0.5g citric acid, 0.5g glucose, 0.25g dodecylamine, 5g oleamide propyl betaine, 3g limonene, 10g n-propanol and 80.75g water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 200 ℃ and 0.4 MPa for 6 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0029] Example 4

[0030] 2g citric acid, 4g glucose, 2g dodecylamine, 8g lauramide propyl hydroxysulfonyl betaine, 6g toluene, 15g propylene glycol and 73g water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 180 ℃ and 0.5 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0031] Example 5

[0032] 2g citric acid, 4g glucose, 2g dodecylamine, 8g cocamidopropyl hydroxysulfonyl betaine, 6g toluene, 15g ethylene glycol and 73g water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 180 ℃ and 0.5 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0033] Comparative Example 1

[0034] A nano-permeation oil displacement agent, namely lauramidopropyl betaine LAB-35, was purchased from Linyi Lusen Chemical Co., Ltd.

[0035] Comparative Example 2

[0036] 9g of limonene, 18g of isopropanol, 18g of fatty alcohol polyoxyethylene ether AEO-9 and 55g of KCl aqueous solution (concentration 50g / L) were weighed and mixed to prepare a nano-permeation oil displacement agent.

[0037] Comparative Example 3

[0038] 4g xylene, 12g ethylene glycol and 84g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 140 ℃ and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain the oil displacement agent.

[0039] Comparative Example 4

[0040] 1g citric acid, 2g glucose, 1g hexadecylamine, 4g xylene, 12g ethylene glycol and 80g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 140 ℃ and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0041] Comparative Example 5

[0042] 1g citric acid, 2g glucose, 1g hexadecylamine, 6g lauramide propyl betaine, 12g ethylene glycol and 78g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 140 ℃ and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0043] Comparative Example 6

[0044] 1g citric acid, 2g glucose, 1g hexadecylamine, 12g ethylene glycol and 84g distilled water were mixed evenly and placed in a sealed reaction vessel. The mixture was reacted at 140 ℃ and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain the nano-permeation displacement agent.

[0045] Performance testing

[0046] Interface tension testing method:

[0047] 1. Testing instrument: TX-500C interfacial tension meter;

[0048] 2. Test temperature: 60 ℃, 6,000 r / min;

[0049] 3. Test oil phase: The oil phase is crude oil: diesel oil = 1:1, and the crude oil viscosity is 3 mPa·s;

[0050] 4. Test water: 3% NaCl and 1% CaCl2 with a mineralization of 1%.

[0051] 5. Test samples: The oil displacement agents prepared in Examples 1-5 and Comparative Examples 1-6 were mixed with test water with a mineralization of 3% NaCl and 1% CaCl2 to prepare test samples with a concentration of 0.5%.

[0052] Methods for testing the rate of oil recovery through seepage:

[0053] 1. Porosity: Record the mass of the core dried to constant weight as m1, then saturate the core with distilled water and record the mass of the saturated core as m2. Calculate the pore volume PV: PV = (m2 - m1) / ρ. Measure the diameter and length of the core using calipers and calculate the core volume. The ratio of pore volume to core volume is the porosity. The porosity of the core used in this application for testing the seepage recovery rate is 18%~20%.

[0054] 2. Determination of water phase permeability in the core: The dried core was placed in a core holder, and distilled water was injected into the core at an injection rate of 2 mL / min. After the injection pressure stabilized, the pump was stopped, and the pressure difference between the two ends of the core was recorded. The water phase permeability of the core was calculated using Darcy's formula. The water phase permeability of the core used for testing the seepage recovery rate in this application was (0.3~0.5)×10⁻¹⁰. -3 μm2 .

[0055] 3. Core Saturation with Crude Oil: Crude oil is saturated using a vacuum method. The dried core is placed in an extraction device, which is then connected to a vacuum pump. The oil suction valve is opened, and after the crude oil has submerged the core, the suction valve is closed, maintaining negative pressure for 4 hours. The saturated core is then placed in a 90℃ oven for aging for 12 hours.

[0056] 4. Static Percolation Test Method: The percolation performance of the samples was evaluated using the Amott method. The core sample and percolation fluid after saturation with crude oil were placed in an Amott flask, and the temperature of the percolation fluid was maintained at 60°C. The volume of oil extracted at different time points was recorded, and the percolation recovery rate was calculated. The concentration of the percolation fluid was 500 mg / L, prepared by mixing the oil displacement agents prepared in Examples 1-5 and Comparative Examples 1-6 with test water containing 3% NaCl and 1% CaCl2, respectively.

[0057] Table 1. Oil recovery rates of different systems

[0058]

[0059] Table 2. Interfacial tension of different systems before and after hot rolling

[0060]

[0061] As can be seen from Tables 1 and 2, the nano-permeation displacement agent prepared in the embodiments of the present invention has a good permeation recovery rate for crude oil, and the interfacial tension of the embodiments does not change much before and after hot rolling, which indicates that the nano-permeation displacement agent prepared in the embodiments has good temperature and salt resistance.

[0062] Compared with Comparative Example 1, the nano-permeable oil displacement agent in Example 1 exhibits significantly better permeable oil recovery, interfacial tension in brine, and temperature resistance than existing amphoteric surfactants used in permeable oil displacement. Compared with Comparative Example 2, the permeable oil recovery of conventional nanoemulsions is lower than that of the nano-permeable oil displacement agent of this invention, which is related to the magnitude of interfacial tension. Compared with Comparative Example 3, Example 1 shows that amphiphilic carbon nanoparticles and surfactants can significantly improve permeable oil recovery and reduce interfacial tension. Compared with Comparative Example 4, Example 1 demonstrates that surfactants facilitate the formation of nanoemulsions and have a significant effect on improving permeable oil recovery and reducing interfacial tension. Compared with Comparative Example 5, Example 1 shows that organic solvents can help improve permeable oil recovery, which is related to the solubilizing effect of organic solvents. Compared with Comparative Example 6, Example 1 demonstrates that both organic solvents and surfactants have a significant effect on improving permeable oil recovery and reducing interfacial tension.

[0063] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0064] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a nano-imbibition oil displacement agent, characterized in that, The method comprises the following steps: reacting citric acid, glucose, long-chain amine, surfactant, organic solvent, short-chain alcohol and water at 140-200 ℃ and 0.4-0.5 MPa for 6-16 hours to obtain the nano-imbibition oil displacement agent; the citric acid is used in an amount of 0.5-2% by mass, the glucose is used in an amount of 0.5-4% by mass, the long-chain amine is used in an amount of 0.25-2% by mass, the surfactant is used in an amount of 5-8% by mass, the organic solvent is used in an amount of 3-6% by mass, the short-chain alcohol is used in an amount of 10-15% by mass, and the balance is water; the long-chain amine is C8-C16 alkyl amine; the surfactant is betaine surfactant; the betaine surfactant comprises one or more of lauryl amide propyl betaine, cocamide propyl betaine, oleamide propyl betaine, lauryl amide propyl hydroxysulfobetaine, cocamide propyl hydroxysulfobetaine and oleamide propyl hydroxysulfobetaine; the organic solvent is one or more of dimethylbenzene, toluene and limonene; the short-chain alcohol is one or more of ethanol, isopropyl alcohol, n-propyl alcohol, ethylene glycol and propylene glycol.

2. A nano-imbibition oil displacement agent, characterized by, The nano-imbibition oil displacement agent is prepared by the preparation method of claim 1.

3. Application of the nano-imbibition oil displacement agent prepared by the preparation method of claim 1 to oil displacement in low-permeability oil reservoirs.

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